* GB786239 (A)

Description: GB786239 (A) ? 1957-11-13

Improvements in thermostatic control devices

Description of GB786239 (A)

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BE547217 (A) CH345700 (A) DE1125094 (B) FR1151543 (A) NL92738 (C) US2786990 (A) BE547217 (A) CH345700 (A) DE1125094 (B) FR1151543 (A) NL92738 (C) US2786990 (A) less Translate this text into Tooltip

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PATENT SPECIFCATION -786,239 Date of Application and filing, Complete Specification: Dec 15, 1955. No 36023155. Application mode in United States of America on April 28, 1955. Complete Specification Published: Nov 13, 1957. Index at Acceptance:-C Gass 38 ( 5),' Bl S( 2 C 2: 12), B 2 (A 5 A 2: E). International Classification:-H 02 e. The inventor of this invention in the sense of being the actual deviser thereof within the meaning of Section 16 of the Patents Act, 1949, is Russell Frederick Garner of Robertshaw Thermostat Divisions Robertshaw Fulton Controls Company, Youngwood, Pennsylvania, United States of America, a citizen of the United States of America.

COMPLETE SPECIFICATION- Improvements in Thermostatic Control Devices. We, ROBERTSHAW FULTON CONTROLS COMPANY, a Corporation organized under the laws of the State of Delaware, United States of America, of 110, East Otterman Street, Greensburg, Pennsylvania, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to thermostatic control devices for electric heating means and more particularly to apparatus for indicating the relative position of the thermally responsive means thereof. According to the present invention there is provided a control device for electric heating means comprising thermally responsive means actuable between controlling positions at a temperature setting for controlling supply of electric current to the heating means, manually operable means for moving the thermally responsive means so that it is actuable at a desired temperature setting, first electrical means including first indicating means for giving indications when said thermally responsive means is manually moved to an off or on position and second electrical means operatively connected to said first electrical means and including second indicating means for indicating when said thermally responsive means reaches the desired temperature. For a better understanding of the invention reference will now be made to the accompanying drawing which is a schematic showing of a control and indicating system embodying this invention. Referring more particularly to the drawing, the control and indicating system is shown as comprising a cup-shaped casing 10 and lPrice 3 s 6 d l 43 ti provided with a cover 12 for the open end thereof which carries a centrally disposed threaded bushing 14 An adjusting screw 16, preferably provided with left-hand threads, is cooperable with the bushing 14 and carries 45 on its exterior end the usual knob 18 by means of which the adjusting screw 16 can be rotated. Thermally responsive means in the form of an expansible and contractible diaphragm 50 element 20 is carried on the interior end of the adjusting screw 16 and has an operating: button 22 projecting therefrom The interior of the diaphragm 20 is in communication with a capillary tube 24 which extends exteriorly 55 of the cover 12 for communication with the usual bulb element 26 to be located in a medium requiring thermostatic control As is well known, the temperature responsive means contains a fluid which expands upon 60 the bulb being heated and serves to actuate the diaphragm 20 sufficiently to operate the parts to be described. The button 22 abuts a depression 28 formed in the face of a main

actuating lever 30 of a 65 snap-action means The main actuating lever is provided at one end with a knife edge 32 which is cooperable with a support 34 projecting from the casing 10 The opposite end of the lever 30 is also provided with a 70 knife edge 36 around which one end of a coil spring 38 is hooked. A main control lever 40 of generally Hshaped configuration is provided with a knife edge 42 formed in the center wall thereof for 75 receiving the opposite hooked end of the coil spring 38 The lower legs are each provided with a knife edge 46 for cooperation with suitable supports 48 Pairs of fixed contacts are carried by the casing 10 to be respec 80 Melee ' tively cooperable with a double pole insulated contact bridge 52 carried by each of the upper legs of the main control lever 40 The switch 50, 52 may be suitably connected in an electric circuit to control energization of a heating means The assembly forms a snapaction means of well-known type and further description is hence unnecessary. Should the temperature of the bulb 26 increase the diaphragm 20 will expand in a manner well known in the art to cause movement of the button 22 to the left to pivot the lever 30 on the support 34 to cause overcenter snap action movement of the lever 40 and opening of the switch 50, 52 A decrease in the temperature of the bulb 26 will cause snap movement of the lever 40 in the opposite direction to cause closing of the switch 50, 52. The knob 18 may be calibrated to various settings and it will be obvious that rotation thereof serves to vary the position of the diaphragm 20 and thus the temperature at which the switch 50, 52 will be closed Clockwise rotation of the knob 18 increases the operating temperature of the device Extreme counterclockwise rotation of the knob 18 places the device in an " off " position which is shown in the drawing wherein the diaphragm 20 is in the extreme left position. Thermostatic devices of the character thus far described are well known in the art and further description is deemed unnecessary. A housing 58 is fixed to one end of the casing 10 by a bracket 60 and encloses a switch means now to be described A flexible arm 62 has one end extending between two of three insulating blocks 64 to project from the housing 58, the other end carrying a fixed contact 66 and being free for movement. The blocks 64 are attached to the interior surface of the housing 58 by a screw 68 which is suitably insulated from the arm 62 and the switch arms now to be described. A second arm 70 is fixed to one of the blocks 64 and has one end projecting from the housing 58, the other end carrying a contact 72 engageable with the contact 66 The flexible switch arms 70, 62 are positioned to have their inherent bias tending to hold the contacts

72, 66 in an open position as shown. A third and shorter arm 74 is positioned intermediate the arms 62, 70 and is fixed between two of the blocks 64 to have one end projecting from the housing 58 The free end of the arm 74 is provided with a contact 76 which is engageable with a contact 78 positioned on a medial portion of the arm 70. The arm 74 is positioned with respect to the arm 70 to have its inherent bias tending to hold the contacts 76, 78 in closed position as shown A stop 80 extends from the end block 64 and serves to limit movement of the arm 74 by its inherent bias as will later be described. To impart movement to the arm 62, a pin 82 is slidably positioned in a bore 84 in the housing 58 to have one end engaging the arm 62, the other end projecting from the housing 58 to engage one end of a lever 86. The lever 86 is suitably pivoted on the 70 bracket 60 by a pin 88 and has the other end thereof engaging one end of a pin 90 The pin 90 is slidably positioned within a bushing 92 suitably fixed in the wall of the cover 12 to have the other end thereof engaging an 75 extending portion 94 of the lever 30. Should the lever 30 pivot counterclockwise, the pin 90 will cause the lever 86 to pivot clockwise about the pin 88 to cause movement of the pin 82 toward the arm 62 The 80 pin 82 being in engagement with the arm 62 forces the arm 62 to flex to the left causing engagement of the contacts 66, 72 Further movement of the pin 90 will cause flexing to the left of both arms 62, 70 with the con 85 tacts 66, 72 remaining in a closed position. This also allows flexing to the left of the arm 74 by its inherent bias which maintains engagement of the contacts 76, 78 in a closed position as shown Should still further move 90 ment of the arms 62, 70 occur, the arm 74 will flex further to the left to engage the stop 80 which will prevent further movement thereof and permit opening of the contacts 76, 78 upon still further movement of the arms 95 70, 62. The end of the arm 62 is connected by the lead wire Ll to a source of electric current The end of the arm 70 is connected in series with an incandescent lamp 96 by 100 the lead wire L 2 which completes the circuit to the source The arm 74 is connected in series with an incandescent lamp 98 by a lead wire 100 which is connected to the lead wire L 2 at a terminal 102 Thus, the lamp 105 98 is in a parallel circuit with the lamp 96. It can be seen that the contacts 66, 72 control energization of the lamps 96 and 98, and that the contacts 76, 78 control energization of the parallel branch containing the lamp 98 110 Operation As the knob 18 is rotated from the " off" position as shown to a temperature

setting, the lever 30 pivots counterclockwise on the support 34 This movement causes the pin 90 115 to rotate the lever 86 clockwise on the pin 88 to cause movement of the pin 82 Movement of the pin 82 causes movement of the arm 62 to the left to close the contacts 66, 72 thus completing the circuit to energize the light 96 120 and the temperature indicating light 98 This condition is set to occur by adjusting the lever 86 to close the contacts 66, 72 when the lever 30 is halfway between its position when the knob 18 is in an "off" position 125 and its position when the contacts 50, 52 snap close. As the knob 18 is rotated still more to the desired setting, the arm 62 moves still further to the left carrying with it the arm 70 with 130 786,239 It will be noted that since the cycling position of the lever 30 is constant for any temperature setting of the knob 18, the device will operate at any temperature setting without adjustment 70 Although a preferred embodiment of this invention has been shown and described herein, it is to be understood that the invention is not limited to the details of construction and arrangement of parts disclosed 75

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* GB786240 (A)

Description: GB786240 (A) ? 1957-11-13

Roadway section for bridges and similar supporting structures

Description of GB786240 (A)

PATENT SPECIRCATION 736,1240 f f i ' Date of Application and filing Complete Specification: Dec30, 1955.

No 37377155. Application made in Germany on Dec 31, 1954. Complete Specification Published: Nov 13, 1957. Index at Acceptance:-Classes 20 ( 2), F 1 B 2; and 20 ( 4), D( 4:14). International Classification:-E 04 c, f. COMPLETE SPECIFICATION Roadway Section for Bridges and Similar Supporting Structures. We, AKTIENGESELLSCHAFT FOR UNTERNEHMUNGEN DER EISEN-UND STAHLINDUSTRIE, of Altendorferstrasse 103, Essen, Germany, a German Body Corporate, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which-it is to be performed, to be particularly described in and by the following statement:The roadway sections of bridges and similar supporting structures have hitherto generally comprised longitudinal beams disposed between or above transverse beams. The decking of these roadway sections has been formed by reinforced concrete plates, wooden planks, or in special instances corrugated metal plates or the so-called orthotropic plates The roadway sections of portable bridges normally consist of longitudinal beams and transverse wooden planks Such roadway sections are constructed by first laying down the longitudinal beams, then placing the decking members upon the longitudinal beams and then securing the decking members individually to the longitudinal beams Finally channel section members were fitted to the edges of the roadway section Particularly when wooden planks were employed as the decking, rattling of the roadway and heavy wear resulted Also the life and the load-bearing capacity of such roadway sections were limited. The invention is based on the idea of reducing the number of individual structural elements of the roadway section, such as longitudinal beams, transverse planks, channel section edge members and connecting means therefor The invention furthermore aims at so designing the individual structural elements that at reduced cost they will yield a roadway of improved load-bearing capacity while facilitating quick assembly of the elements. The invention provides a roadway section for bridges and similar supporting structures which comprises torsionally stiff longitudinally extending hollow boxes of completely enclosed section supported on transverse beams, cap plates which are wider than the hollow boxes, have downwardly bowed upper 50 surfaces and are disposed between adjacent hollow boxes, the cap plates closing the spaces between the hollow boxes at the top only and being welded at their edges to the upper edges of the hollow boxes and stiffening walls dis 55 posed in the spaces between the hollow boxes beneath the caps, the stiffening walls extending at right angles to: the hollow boxes with their bottom

edges level with the bottom edges of the hollow boxes and being welded 60 both to the hollow boxes and to the cap plates Preferably, the hollow boxes are of rectangular cross section The hollow boxes and the cap plates may extend in sections from one transverse beam to the next It is 65 expedient to constitute the edges of the roadway of hollow boxes the outer walls of which extend upwardly and are bent outwardly at their upper ends For purposes of anchoring adjacent portions of the structure the lateral 70 walls of the hollow boxes and also the stiffening walls are provided with holes through which extend connecting bolts For purposes of fastening the cap plates to the transverse beams, the stiffening walls are provided with 75 lugs The hollow boxes may be filled with a hardenable mass such as concrete. Certain embodiments of the invention will now be described by way of example with reference to the accompanying drawing in 80 which:Fig 1 is a perspective view of a roadway section, Fig 2, 3 and 4 represent diagrammatic illustrations of alternative forms of roadway 85 sections, Fig 5 shows on an enlarged scale the connection between two adjacent hollow boxes, and Fig 6 is a section taken along the line 90 VI-VI in Fig 5. The roadway shown in Fig 1 comprises transverse beams I torsion resistant hollow boxes 2 of rectangular section and cap plates 3 interposed between the boxes The upper surfaces of the cap plates 3, which are wider than the boxes 2, are downwardly bowed The cap plates are welded at their edges to the boxes 2 Beneath the cap plates 3 ares spaced stiffening walls 4 welded both to We cap plates 3 and to the boxes 2 The hollow boxes and the cap plates are of about equal thickness and they are braced together in the completed roadway. At the central part of the roadway there are provided two adjacent pairs of hollow boxes 2 which extend in sections from one transverse beam to the next transverse beam. Each outer edge of the roadway is formed by a hollow box the outer wall 5 of which extends upwardly and is bent outwardly at its top edge. In the arrangement shown in Fig 2, the hollow boxes 2 and cap plates 3 alternate with one another. Fig 3 shows a roadway section in which the edges are formed by cap plates which vary in cross section in conformity with the respective shape of the connecting edge members of the bridge; see the cross sections of the cap plates at the left and right-hand sides of Fig 3. In order to anchor the members 2 and 3 together, i e in order to prevent them from displacement in the longitudinal as well as in the transverse direction, the lateral walls of the hollow boxes 2 and the stiffening walls 4 are provided with holes 6 through which bolts 7, 8 are passed These bolts extend into corresponding holes in the

adjoining parts of the structure as is evident from Figs 5 and 6. To fasten the cap plates 3 to the transverse beams 1, the stiffening walls 4 are provided with lugs 9 which are connected to the transverse beams by bolts The adjoining stiffening wall is provided with recesses 10 (Fig 6) to accommodate the lugs. The roadway sections may be constructed of light metal It may sometimes be expedient to fill the hollow boxes with a filling material such as concrete.

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* GB786241 (A)

Description: GB786241 (A) ? 1957-11-13

Improvements in or relating to apparatus for the continuous conversion ofpig iron to steel, and in the method of operating said apparatus

Description of GB786241 (A)

_ A E Lii ( PECIFICATIO PATENT SPECIICATION 78 G,241 Date of Application and filing Complete Specification: Jan 9, 1956. No 719156. Application made in Germany on Jan 8, 1955. Complete Specification Published: Nov 13, 1957. Index at Acceptance:-Class 72, D 3 G( 1 B: 1 M: 2 A 1: 7 H 2). International Classification:-C 21 b. COMPLETE SPECIFICATION Improvements in or relating to Apparatus for the Continuous Conversion of Pig Iron to Steel, and in the Method of Operating said Apparatus. We, AUGUST TH Ys SEN-HUTTE AKTIENGESELLSCHAFT, of Duisburg-Hamborn Germany, and Do RT Mu ND-H 6RDER HCTTENUNION AKTIENGESELLSCHAFT, of

Dortmund, Germany, both bodies corporate organised under the laws of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - There are many known methods and apparatus for converting a continuous stream of pig iron to steel by blowing gaseous refining media on to or into said stream It is a common feature of all these known methods and apparatus that the direction of flow of the pig iron stream should be horizontal or slightly inclined In order to control correctly the reactions which then take place one after the other or simultaneously it has often been proposed to provide reaction compartments which can be charged with slags of different composition It has also been proposed to charge the reaction slag so that it flows in countercurrent to the pig iron In carrying out such a method the apparatus ensures that pig iron and slag flow substantially horizontally and in counter-current with respect to one another. The object is to ensure that the fresh highlyreactive slag comes into contact with and acts upon the already partly refined metal. It has further been proposed to convert to steel a freely flowing stream of pig iron by blowing oxygen-containing refining gases thereon, if necessary introducing powdered slag constituents into the stream of gas By using such an apparatus, the slag formed would be led away directly with the pig iron and could react subsequently in any desired container with the metal which has already been partly refined. All these proposals create difficulties in providing between the iron and the slag the requisite conditions, as regards reaction time lPrice 3 s 6 d l and contact between metal and slag, for carry 45 ing out the reactions. It has now been found that it is possible, when converting by any method comprising blowing a gaseous refining medium, to allow all the refining reactions, for example, not only 50 decarburisation and dephosphorisation but also slagging of the silicon and manganese, to proceed simultaneously and completely provided all the components relevant to the refining, for example, oxygen, pig iron and slag, are quan 55 titatively measured out accurately and simultaneously and allowed to flow together continuously until the capacity of the refining container is reached. This method can be carried out by blowing 60 gaseous refining media on to the surface of the molten bath. Apparatus, according to this invention, for the continuous conversion of pig iron to steel by blowing-on oxygen-containing refining 65 media, is characterised by a container which is provided at the top

with supply means for a stream of pig iron, for refining gas, and for slag-forming materials or cooling media, with an aperture at the bottom for tapping off the 70 finished steel, and with a slag overflow aperture The container may be elongated in elevation and round in cross-section. Preferably, a siphon is associated with the bottom opening through which the finished 75 steel is drawn off, the siphon being provided with an overflow slightly above the desired level of the metal in the container In addition, the container is preferably provided with a cover having openings for the passage of pig 80 iron, for supplying gaseous refining medium, and for supplying slag-forming materials or cooling media, and for allowing waste gas to escape. This apparatus enables all the components 85 which have to act on and react with one another, for example, oxygen, pig iron and slag, to be brought together at the temperature C 4 s. required for the reaction, at the same point in such manner that all the reactions take place at the same time and that, unhindered by the operations at this reaction zone, the steel, of the desired final composition, and the surplus slag are tapped off continuously and with substantially constant composition, and at substantially the same temperatures. One embodiment of the invention is illustrated in the accompanying drawing, which is a diagrammatic sectional elevation. A container 1, of elongated elevation and round cross-section, is provided, and into this container is fed a stream 2 of molten pig iron and, through a blowing nozzle 3 which may be water-cooled, a supply 4 of oxygencontaining refining gas The streams of pig iron and gas are conveyed uniformly and continuously to the surface 5 of the molten bath 6 in the said container 1 At the same time a charging device 7 of any known kind continuously or intermittently delivers slagforming material or cooling media 8 of any desired kind on to the surface 5 The finished steel flows out of the container continuously through an opening 9 at the lowest part of the container 1 in such a manner that during the refining operation, and with a uniform supply of pig iron, the surface level 5 of the metal remains at the same height Suitable regulation can be effected by varying the size of the outlet opening 9 or, if the outlet opening is to remain of constant size, by joint regulation of the pig iron supply and the supply of refining gas However, this regulation may be carried out by allowing the steel issuing from the opening 9 at the bottom of the container to flow through a siphon 10 with an overflow 11; because of the sum of pressures of the metal and slag column in the container the surface of the metal 5 in the container will lie slightly below the overflow 11 Above the surface of the metal a constant layer 12 of slag is

maintained by providing the container 1 with a slag overflow 13 at a suitable level. The supply of pig iron 2 and the supply of oxygen-containing refining gas 4 are adjusted automatically to one another in any known manner; for example, the pig iron and the oxygen-containing refining gas are supplied from separate storage containers 14 and 15, respectively It is important that pig-iron and refining gas be supplied always in the same weight-ratio in each unit of time, and that means be provided for observing that this is achieved; for example, the two containers 14 and 15 are so mounted on a weighing device 16 that the output of pig-iron and refining gas from the respective containers at the desired weight-ratio will retain the two containers balanced against each other on said weighing device Any other kind of constant automatic pr manual quantity regulation of the pig iron and of the oxygen-containing refining gas may be used. A cover 17 may be disposed above the container 1 for reducing radiation, the said cover providing, in addition to an opening 18 for the pig iron, an opening 19 for the nozzle 3 for the gaseous refining medium, and an opening 70 for the material 8, a further opening 21 for the escape of waste gas; in some cases, however, a plurality of these streams and device may pass through one opening. The container 1 and cover 17 are provided 75 with a ceramic, refractory lining According to the capacity of the apparatus, it is possible to work with one or more gas streams 4 blowing on to the surface 5 and also with one or more streams 2 of pig iron Similarly, one or more 80 charging devices 7 for solid additions 8 may be provided. The refining gas 4 may be technically pure oxygen, air, CO 2, H 20, employed either separately or in any desired mixture 85 If a plurality of blowing nozzles are used, or one nozzle with a plurality of jets, it is particularly advantageous to blow one or more jets through the slag layer 12 on to or into the metal bath 6, and to blow the other jet or jets 90 on to or into the slag 12; thereby, it is possible, for a pre-determined degree of oxidation of metal and slag, to adjust the carbon content of the metal within wide limits, by varying the P content or the Mn content in the metal and 95 the Fe O content of the slag. The apparatus according to the invention combines all the advantages of constructional simplicity, to make it possible to carry out a continuous operation of this kind in a tech 100 nically satisfactory and therefore reliable and economical manner.

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* GB786242 (A)

Description: GB786242 (A) ? 1957-11-13

Improvements in valve actuator mechanisms for internal combustion engines

Description of GB786242 (A)

PATENT SPECIFICATION 784 s al ii; Date of Application and filing Complete Specification: Jan 10, 1956. y&/it F "i% No 815/56. Application made in United States of America on Jan 20, 1955. Application made in United States of America on Jan 20, 1955. Complete Specification Published: Nov 13, 1957. Index at Acceptance:-Classes 7 ( 2), B 4 G; and 7 ( 6), B 2 P( 13 27 A). International Classification:-FO 2 b, f. COMPLETE SPECIFICATION Improvements in Valve Actuator Mechanisms for Internal Combustion Engines. We, GENERAL MOTORS CORPORATION, a Company incorporated under the laws of the State of Delaware in the United States of America, of Grand Boulevard in the City of Detroit, State of Michigan, in the United States of America (Assignees of RONALD KRAKE EVANS, CHARLES AUGUSTINE CHAYNE and JOHN DOLZA) do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:This invention relates to poppet valve actuator mechanisms for internal combustion engines utilising rockers for transmitting valve opening and closing movements to and from the valve, and in particular to a valve rocker mounting adapted to automatically adjust its fulcrum to compensate for wear and other factors which affect the

lash or operating clearance between the rocker and other parts operatively associated with it. In the invention the fulcrum of a rocker for transmitting motion from a push rod to a poppet valve is mounted on a member which extends through the rocker intermediate the ends thereof and which forms part of a dash pot assembly mounted on the engine cylinder head and having a spring arranged to move the fulcrum to take up any valve lash. The scope of the invention is defined by the appended claims; and how it can be carried into effect is hereinafter particularly described, with reference to the accompanying drawings, in which:Fig 1 is a transverse section through part of a V-type internal combustion engine incorporating a valve rocker hydraulic lash adjuster mechanism in accordance with the invention; Fig 2 is an enlarged section view of the lash adjuster mechanism shown in Fig 1; Figs 3, 4 and 5 show three modifications lPrice 3 s 6 d l of the lash adjusting mechanism of Figs 1 45 and 2; Fig 6 is a transverse section through part of a V-type internal combustion engine incorporating a further embodiment of a valve rocker hydraulic lash adjuster mechanism in 50 accordance with the invention; Fig 7 is an enlarged section of the lash adjuster mechanism shown in Fig 6; Fig 8 is a view' on the line 3-3 of Fig 7; and 55 Figs 9 and 10 are modifications of the construction shown in Fig 7. Figs 1 and 2 of the drawings show a frame member for a V-engine including a crankcase 1 and a cylinder head 2 An engine 60 driven cam 3 drives the tappets 4, each of which operates a poppet valve 7 by means of a push rod 5 and a valve rocker 6 As shown, the rocker 6 is of upwardly dished configuration and its ends overlie the upper ends of 65 the push rod 5 and the stem of the valve 7, each of which protrudes above the cylinder head 2 Lubricating oil is fed to the rocker 6 through the push rod 5 and tappet 4 which are made hollow for this purpose, the tappet 70 4 being slidably mounted in the crankcase and having registering openings 8 communicating with an oil pressure gallery 9 The upper end of each push rod 5 has a port 10 (Fig 2) registering with a port 10 ' extending 75 through the end of the rocker 6, and intermediate its push rod end and the stem of the valve 7 the rocker 6 is provided with a spherical beaning surface 1 1 to which the oil flows from the port 10 ' Excess oil is normally 80 supplied through the push rod 5 stated so as to flow over the valve end of the rocker 6 and lubricate its valve actuating surface 12. Centrally of the rocker bearing surface 11 is an aperture 13 through which extends a stud 85 14 having a rocker bearing member 15 secured O at its upper end by a nut 16 The lower face of the bearing member 15 is also 1,242 A-risw-i;-" 2 786242 made spherical to conform with the rocker beatiig surface 11, but a relief groove 17 is provided in the

bearing member 15 to ensure a substantial drainage of oil through the rocker aperture 13 during operation The valve 7 has a valve return spring 17 ' arranged between the upper end of the valve stem and the cylinder head 2. As shown in Fig 2, the cylinder head has below the rocker 6 an internally threaded opening 18 into which is screwed a dash pot cylinder 19 into which the lower end of the stud 14 extends, the bore 20 of the dash pot being substantially larger than the periphery of the stud 14 so that a pressure chamber 21 is formed between them Slidably fitting in the bore 20 and forming the lower end of the pressure chamber 21 is a cup shaped plunger 22 whose end wall 23 is apertured to embrace the stud 14 and rests on a flange 24 formed on the lower end of the stud 14 Completing the plunger 22 is a gasket 25 which forms a seal to prevent the escape of oil between the plunger end wall 23 and the flange 24 The stud 14 does not abut the cylinder end wall 26 but is spaced axially therefrom to form an oil reservoir 27 A guide sleeve 28 is slidably mounted on the stud 14 within the cylinder and has a flange 29 by which the guide sleeve is seated on the open end of the dash pot, a sealing gasket 30 being interposed between the flange 29 and said open end of the dash pot The guide sleeve 28 is secured against movement outwardly of the dash pot 19 by a nut 31 which is screwed on to the threaded upper end of the dash pot and has a shoulder 32 between which and the end of the dash pot is clamped the guide sleeve flange 29, the latter forming the upper end wall of the pressure chamber 21, and having an oil passage 33 therethrough in which is seated a ball check valve 34 A compression spring 35 acts between the plunger end wall 23 and the flange 29 to bias the stud 14 and plunger 22 inwardly of the dash pot 19, the upper end of the spring 35 seating against a washer 36 whose outer diameter is sufficiently large to partially underlie a counterbored lower end of the passage 33 in which the ball check valve 34 is housed, and thereby to limit opening movement thereof The upper face of the guide sleeve flange 29 is relieved by a transverse groove 37 which connects the upper end of the passage 33 with the periphery of the stud 14 The interior of the nut 31 above the guide sleeve flange 29 forms an upper oil reservoir 38 into which oil can drain through the rocker opening 13, and an annular filter element 39 pressed into the nut 31 against the flange 29, prevents any foreign particles being carried by the oil into the groove 37. The upper and lower reservoirs 38 ansd 27 are interconnected by longitudinal and transverse passages 40 and 41 in the stud 14, constant communication of the transverse passages 41 with the groove 37 being ensured by an annular groove 42 in the periphery of the stud 14 at this point.

During operation, with each lift stroke of the cam 3 its motion is transmitted through 70 the tappet 4, push rod 5 and rocker 6 to open the valve against the valve return spring 17 ', the resultant upward thrust of the rocker against its bearing member 15 tending to move the stud 14 outwardly of its dash pot 75 cylinder 19, and this movement of the stud 14 being resisted by the spring 35 and oil under compression in the pressure chamber 21, the check valve 34 moving to its seated position and closing the passage 33 in the 80 flange 29 The pressure thus exerted on the oil iin chamber 21 results in a certain amount of relatively slow leakage therefrom between the surfaces of the plunger member 22 and the cylinder bore 20, and between the guide 85 sleeve 28 and the stud 14, the escaping oil respectively entering the lower reservoir 27 and the upper reservoir 38 by way of the collecting groove 42 to the transverse groove 37. As the portion of the upper reservoir 38 con 90 stituted by the transverse groove 37 is normally maintained full of oil, such leakage oil flowing thereto from the pressure chamber 21 is transferred via the drilled passages 41 and to the lower reservoir 27 After the valve 95 7 reaches its fully open position and begins its return to its seat upon continued rotation of the cam 3 the oil pressure within the chamber 21 and the leakage of oil therefrom to the reservoirs 38 and 27 continues until the valve 100 7 reaches its fully closed position At this point in the cycle the plunger return spring acts to return the rocker fulcrum axis to its initial position by moving the stud 14 downwardly into the dash pot cylinder 19 and 105 the resultant drop in oil pressure within the chamber 21 allows the check valve ball 34 to open the passage 33, permitting oil to flow into the pressure chamber 21 to replace that which was lost by leakage during the valve 110 lift and return strokes The action described is repeated for each valve opening and closing cycle, and because there is little opportunity for oil to escape past the filter 39 such replenishment of the pressure chamber 21 115 with oil as takes place from the groove 37 of the upper reservoir 38 is substantially equalised by replenishment of groove 37 with oil from the lower reservoir 27 via the drilled passages 40 and 41 Accordingly, a recircu 120 lating oil flow action takes place within the dash pot which is substantially the equivalent of that occurring in the so-called " self-contained " type of valve lash adjusters which have no external fluid supply Such replenish 125 ment as may be needed is provided for by delivery of engine lubricating oil into the nut 31 through drainage from the rocker opening 13, there being sufficient oil at all times during engine operation to cover the filter ele 130 786,242 openings 243, and aligned with these openings are somewhat larger diametrically -opposed openings 244 through the -side walls of the cylinder 219 A cross pin 245 substantially smaller

than the stud openings 243 70 extends through both sets of aligned openings 243, 244 and serves as an abutment for a plunger 246 which is a close sliding fit in the bore 220 of the cylinder 219 Between the upper end of this plunger and the end wall 75 229 of the cylinder 219 is formed an oil pressure chamber 221, which is connected with the reservoir 238 by a cylinder end wall passage 233 Compressed between the wall 229 and the plunger 246 is a plunger return spring 80 235 whose upper end seats against a perforated cage 236 retaining and limiting opening travel of a ball check valve 34 A baffle 247 carried by the stud 214 adjacent the open. upper end of the cylinder head pocket 240 85 serves to collect any foreign particles carried in to the retainer with the oil draining in from the rocker 6 The operation of this form of the invention is fundamentally the same as that previously described with respect to Figs 90 2-4, oil being permitted to leak past the plunger 246 from the pressure chamber 221 at a relatively slow rate while the valve 7 is open and such leakage oil being replenished from the reservoir 221 via the passage 233 during 95 that portion of the cycle when the valve 7 is seated and the thrust load on the rocker 6 is removed As the thrust load on the plunger 246 is always in the same direction during the period when the engine valve is open 100 as well as during the period when the engine valve is closed, there is no lost motion of the cross pin 245 relative to the stud The clearance which the cross pin 245 has in the cylinder side wall openings 244 105 accommodates the relative axial movement of the stud 214 in the cylinder The cylinder 219 is securely anchored by its threaded connection to the engine cylinder head and the cross pin 245 prevents the stud 214 from 10 rotating during initial adjustments of the nut 16 in setting the rocker to its proper height and within the range of automatic adjustment for which the mechanism is designed. The lash adjuster mechanism shown in Fig 115 6 is mounted on an engine which, as in the embodiment shown in Fig 1, has a crankcase 1, a cylinder head 2, a driven cam 3, and tappets 4, each of which latter is connected by a push rod 5 and a, valve rocker 6 to actuate a 120 poppet valve 7, and has openings 8 in its side walls communicating with a crankcase oil pressure gallery 9 The upper end of each push rod has a port 10, best shown in Fig 7, registering with a port 10 ' extending through 125 the end of the rocker. Intermediate its push rod end and the stem of the valve 7 the rocker 6 has its bottom wall 52 spherically depressed to form a bearing surface 53 to which oil tends to flow from the 13 Q ment 39 with oil to a sufficient height to overflow from the upper end of the nut 31 and thereby carry away the greater portion of foreign particles which otherwise might pass through the filter element 39 and contaminate the

oil recirculating between the pressure chamber 21 and the lower reservoir 27. The arrangement described thus serves to maintain the lash or operating clearance in the valve train at a minimum in substantially the same manner as known hydraulic valve lifters which move with the reciprocating parts. The embodiment shown in Fig 3 operates in substantially the same manner, but in this case only a single leakage path is provided for oil escaping from the pressure chamber 21 during the cam lift stroke, the leakage path being between the guide sleeve 28 and the stud 114, and the plunger member 122 being made of a resilient material such as soft synthetic rubber which effectively seals the stud to the bore 20 With this arrangement only the internal wall of the guide sleeve 28 and the external surface of the stud 114 need be machined to the very close tolerances necessary to control the rate of " leakdown " when the rocker thrust is being supported by the stud 114 To prevent too rapid a delivery of leakage oil into the upper reservoir groove 37, from which point it might tend to flow through the filter 39 and be contaminated with foreign particles, the stud 114 is provided with a second oil collecting groove 142 and transverse passage 141 which connect with the longitudinal passage 40 in the stud 114. The modification shown in Fig 4 differs from that of Fig 2 only in that the upper reservoir 38 is formed by an integral enlarged extension 131 of the cylinder 119, instead of a separate nut 31 as shown in Figs 2 and 3. The guide sleeve flange 29 in this modification is press fitted into the lower end of this cylinder extension 131 to hold it in place. In Fig 5 a somewhat different stud and plunger construction is shown, the stud 214 having its portion below the rocker expanded to slidably embrace the dash pot cylinder 219 which is of inverted cup shape and has its lower end threaded into the cylinder head The cylinder 219 extends only partially into the expanded portion of the stud 214, so as to form a reservoir 238 between them The cylinder head 2 is formed with a pocket 240, surrounding the expanded end portion of the stud 214 into which oil may drain from the rocker oil system, and the side wall of the stud above the cylinder 219 is provided with a port 241 connecting the pocket 240 with the reservoir 238 which is also open to atmosphere through an axial passage 242 extending through the upper end of the stud 214. Adjacent the lower end of the stud its side walls are provided with diametrically opposed 786,242 port 10 ', excess-oil being supplied through the push rod 5 so as to flow over the valve end of the rocker and lubricate its valve actuator surface 54. Centrally of the rocker bearing surface -53 is an aperture 55 through

which extends a stud 56 whose lower end is anchored as by threads 57 in a hole 58 provided therefor in the cylinder head 2 The rocker aperture 55 has ample clearance about the stud 56 to accommodate rocking motion of the rocker 6 in which is journaled a cylinder 59 the external bottom and side walls of which form a ball end 60 socketed in the bearing surface 53 The internal side walls of the member 59 form a cylinder bore 61 of substantially larger cross section than the stud 56, and slidably fitted in this bore is a plunger 62 integral with, but may be secured to, the stud 56 The end wall of the member 59 is centrally apertured at 63 for passage of the stud 56, and slidably sealing this aperture to the external periphery of the stud is an annular body 64 of synthetic rubber which is supported by the end wall of the member 59 Between this seal 64 and the plunger 62 is a dash pot chamber 65 which is bounded by the lower end of the bore 61 and the portion of the stud external surface extending through the aperture 63 above the seal 64 Within the chamber 65 and surrounding the stud 56 is a coil compression spring 66 whose lower end seats on the seal body 64 and whose upper end reacts against the plunger 62 so as to urge the member 59 and the rocker 6 toward the cylinder head 2, the upper end of the spring 66 seating against a washer 67 which underlies a counterbore 68 at the chamber end of a passage 69 which connects the opposite ends of the plunger 62 Loosely disposed in the counterbore 67 is a ball check valve 69 ' which is movable under oil pressure within the chamber to close the passage 69 The ball 29 is limited in its opening movement outwardly of the counterbore by the washer 67, there being sufficient freedom for travel of the ball between its seat and the washer to permit relatively free flow of oil into the chamber through the passage 69 when the ball is in engagement with the washer 67 The bore 61 extends above the plunger 62 to form a reservoir 70 for oil to maintain the chamber filled at all times, and forming an extension of the upper end of the side walls of the member 59 is a pressed on sheet metal sleeve 71 which serves to enlarge the oil storage capacity of the reservoir 70 With the rocker occupying a substantially tilted position in a V-type engine as indicated in Fig 6, the maintenance of a sufficient head of oil in this reservoir is further ensured by a baffle 72 extending generally transversely between the channel side walls 73 of the rocker 6 and upwardly from the bottom wall 52 thereof so as to dam the oil in the rocker to a height enabling it to overflow into the sleeve 71. In operation, with each lift stroke of the cam 3 its motion is transmitted through the tappet 4, push rod 5 and rocker 6 to open the valve 7 against its return spring 74, the resul 70 tant upward thrust of the rocker 6 being taken by the member 59 which, in turn, transmits the thrust through the oil in the chamber to the plunger 62 which is

anchored by its stud 56 to the cylinder head The pressure 75 thus exerted on the oil in the chamber 65 results in some leakage of oil therefrom between the plunger and the cylinder bore 61, into the reservoir 70, the check valve 69 being held closed by the chamber oil pressure 80. Owing to such leakage the cup-shaped member and the rocker move slightly upwards towards the plunger 62, in opposition to the relatively light spring 66 Such leakage, or " leakdown," continues until the cam 3 has 85 rotated sufficiently to permit the engine valve 7 to return to its fully seated position shown, after which all thrust on the body of oil in the cushion chamber 65 is relieved As the valve 7 will reach its seated position before 90 the tappet 4 fully returns to the base circle of the cam 3, continued rotation of the cam -at this point in the cycle tends to create an operating clearance, or " lash," in the valve operating linkage, which is largely the result 95 of the aforementioned leakdown occurring when the valve 7 was off its seat This lash however, is taken up by the spring 66 maintaining the ball end 60 socketed in the spherical bearing surface 53 of the rocker 6 while 100 urging the rocker downwardly towards the cylinder head 2 As the pressure within the chamber 65 during this time is insufficient to hold the check valve 69 in its seated position shown, oil from the reservoir 70 may flow 105 into the chamber through the passage 69 to replace that which escaped during the previous " leakdown," ready for the start of the next engine valve operating cycle. The rapid oscillation of the rocker 6 causes 110 the oil entering the space between the channel forming side walls 73 of the rocker via the registering push rod and rocker ports 10, 10 ' to be thrown about within the enclosure formed by the rocker cover 75 Particularly 115 at high operating speeds a certain proportion of this oil will be deflected from the rocker cover 75 into the upper end of the sleeve 71, and such oil as tends to build up around the member 59 and between the channel forming 12 G side walls 73 of the rocker will tend to overflow into the sleeve 71, being assisted in this respect by the damming action of the baffle 72. Where the space between the rocker and 125 the top of the rocker cover 75 permits, the upper wall of the rocker cover may be provided with a fixed deflector 76, as shown in Fig 10, which depends from the cover 75 toward the open end of the reservoir 70, and 130 786,242 thereof and which forms part of an hydraulic dash pot assembly mounted -on the engine cylinder-head, the assembly including a spring which acts on the movable member of the assembly to move the fulcrum so as to take 70 up any valve lash. 3 A valve actuator mechanism for an in-

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* GB786243 (A)

Description: GB786243 (A) ? 1957-11-13

Purification of methylnaphthalenes

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

COMPLETE SPECIFICATION Purification of Methylnaphtlhatenes We, E. I. Du PONT DE NEMOURS AND CO., a Corporation organised and existing under the laws of the State of Delaware, United States of America, of Wilmington, Delaware, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the purification of methylnaphthalenes. A known process for producing hydrogen peroxide involves alternately hydrogenating and oxygenating a working solution of an alkylanthraquinone and/or tetrahydroallcylan thraquinone intermediate, the hydrogen peroxide being formed in the oxygenation stage of the cycle where the alkylanthraquinone intermediate is regenerated. In the

process, hydrogenation of the alkylanthrac quinone to the corresponding anthrahydroquinone is effected in the presence of a catalyst such as tinely-divided nickel or metallic palladium on an activated alumina. The solvents generally regarded as most suitable for dissolving tthe intermediates -in the process are mixtures, one constituent of which (e.g. cyclohexanol) is a good solvent for the reduced form and another constituent of which (e.g. benzene) is a good solvent for the oxidised form of the intermediate. The methylnaphthalenes, including the mono and dimethyl-naphthalenes, are excellent solvents for the intermediate in the oxidised form, and they possess certain properties which make their use in solvent mixtures of the type indicated highly advantageous. However the methyinaphthalenes, as obtained commercially, a1 most invariably contain impurities whose presence in the working solution is quite harmful and objectionable. The identities of the impurities are not known, but their effects are readily apparent. Some function as poisons for the hydrogenation catalyst, thus seriously affecting initial operation of the hydrogenation step. Others are strongly adsorbed, or yield compounds which are so adsorbed, by the catalyst, thus reducing catalyst activity and life. The same or similar impurities contaminate, or yield compounds which contaminate, the peroxide product. It is, therefore, important when using methylnaphthalenes as working solution constituents that a practical way be found for purifying commercial methylnaphthalenes prior to their use so as to remove or render innocuous impurities of the type indicated. In accordance with the present invention there is provided a method of purifying a methylnaphthalene which is contaminated by impurities whose presence is objectionable in a working solution of the kind described, which method comprises treating said methylnaphthalene with an aliphatic peracid in the liquid phase which is preferably formed in sit, and separating from said methylnaphthalene products of the reaction of said peracid with said impurities. The commercial methyinaphthalenes are known to comprise mixtures of various substances. Thus, a commercial "monomethyl- naphthalene" from a petroleum source contains about 40% by weight alpha-methyl naphthalene, a large proportion of alkylnaphthalenes, mostly mixed dimethylnaphthalenes, substantial amounts of saturated aliphatic and naphthenic compounds and trace amounts of unsaturated aliphatic compounds and probably of sulphur and nitrogen compounds. Whatever the objectionable impurities may be, it has been found that they react actively with aliphatic peracids to form products which can be readily separated.

Alpha-methylnaphthalene, beta-methylnaphthalene and mixed dimethyinaphthalenes available from coal-tar sources also contain objectionable impurities which react with performic acid to yield products which can be readily separated. The treatment with the peracid can be carried out at any temperature from the freezing point up to the boiling point of the methylnaphthalene, the higher the temperature the greater being the rate of reaction between the peracid and the impurities. Temperatures of from 20 to 60 C. are generally satisfactory and preferred. At such temperatures, reaction times of 3 to 24 hours are preferred but longer or shorter times can be employed to achieve significant beneficial results. Generally, the higher the temperature the shorter the time required to obtain a given beneficial effect. Best results are obtained under any given temperature and time conditions when the reaction mixture is agitated. Pressure does not appear to be an important factor and any pressure can be used provided it is sufficient to maintain the mixture in the liquid phase. The amount of peracid to be used wilt depend somewhat upon the particular methylnaphthalene product being treated and the degree of purification desired. In most instances, amounts of from 2 to 25% based upon the weight of the methylnaphthalene give excellent results, and such amounts are generally preferred. When using such amounts the peracid is usually completely reacted or decomposed at the end of the treatment under the preferred time conditions. Significant improvement in quality can be achieved with smaller amounts e.g. as low as about 0.1%. Much larger amounts e.g. up to 50% and higher, can be used, but such larger amounts are wasteful. It is often advantageous to add the peracid, or the compounds forming the same in situ incrementally since the peracid is used more efficiently under such circumstances. If desired, the reaction products can be separated from the methylnaphthalene after reaction with one or more increments of the peracid, after which the methylnaphthalene can be treated with more of the peracid. A preformed peracid can be used effectively, but its formation in situ is usually more convenient and preferred. Formation in situ can be accomplished by adding any of the reagents known to react with each other to produce the chosen peracid. Thus, aqueous hydrogen peroxide, e.g. having an H202 content of at least 27% by weight, can be added together with concentrated formic acid, e.g. aqueous formic acid containing at least 75% by weight of HCOOH. Either reactant can be used in considerable excess but an excess of formic acid, e.g. at least 2 to 1 moles of HCOOH per mole of H,O, is preferred since excess formic acid serves to moderate the reaction and to avoid formation of

hazardous concentrations of performic acid. Most preferably from 12 to 25 g. of HCOOH, e.g. as aqueous 90% formic acid, and from 2 to 4 g. of H-02, e.g. as aqueous 35% hydrogen peroxide, is used per 100 g. of methylnaphthalene. The reactants can be added in any order or simultaneously, a convenient way being first to add the formic acid to the methylnaphthalene and then to add to the resulting mixture the hydrogen peroxide at a rate such as will maintain the temperature at the desired level. Temperature control can also be achieved by cooling or heating the reaction mixture as required. Other aliphatic peracids can be used in place of performic acid with similar results. Those containing up to 4 carbon atoms constitute a preferred group. If the peracid is formed in site, for example by reacting hydrogen peroxide with acetic, propionic, n-butyric or isobutyric acid, it is preferred that a small amount, e.g. from 0.5 to 5% based upon the weight of the aliphatic acid used, of a strong mineral acid such as concentrated sulphuric acid also be added to catalyze formation of the peracid. Such a catalyst can also be used, but is not generally necessary, when performic acid is to be formed from hydrogen peroxide and formic acid. When a working solution containing methylnaphthalene purified in accordance with the invention is extracted with aqueous hydrogen peroxide, the latter remains relatively odourless and its carbon content is not increased significantly. However, if there is added to such a working solution gum which has been separated from unpurified methylnaphthalene, the aqueous hydrogen peroxide extract of the working solution acquires a strong objectionable odour and its carbon content is detectably increased. Thus, purifying the methylnaphth lene constituent of the working solution by the present method significantly reduces contamination of the product hydrogen peroxide solution obtained by extracting the oxidised working solution with water. The reaction products of the peracid with the impurities are readily separable from the methylnaphthalene by conventional procedures which are well understood in the art of purification. They may be separated for example by fractional distillation, by selective adsorption on an adsorbent material, or by selective solvent extraction using for example concentrated sulphuric acid as the extraction solvent. Countercurrent extraction with diethylene glycol or aqueous methanol is also effective. Separation by fractional distillation with nvo or three theoretical stages with recovery of a middle cut of about 90% by weight as purified product, or by selectively adsorbing the undesired materials

on an adsorbent such as activated alumina, is preferred. Other effective adsorbents are silica-alumina cracking catalyst, silica-magnesia, and synthetic zeolite. It should be noted that merely subjecting the crude methylnaphthalene to fractional disullation or merely treating it with activated alumina or with concentrated sulphuric acid, in the absence of previous treatment with a peracid, is incapable of achieving the degree of purification resulting from the method of the present invention. On the other hand, the method of the present invention gives excellent purification and by its use commercial methylnaphthalene can be rendered much more suitable for use in working solutions for producing hydrogen peroxide. The invention is illustrated by the following examples in which all percentages given are percentages by weight: EXAMPLE I. 1474 g. of a commercial ' methylnaphthalene" of petroleum origin containing about 40% alphavmethylnaphthalene and other materials as previously indicated, was added to a reaction flask provided with a stirrer, a thermometer and a cooling bath. While operating the stirrer, there were added in suc cession 103 g. of aqueous 90% formic acid and 45 g. of aqueous 35% hydrogen peroxide, after which the mixture was stirred for 3 hours while controlling the temperature at 32 to 40 C. The same amounts of formic acid and hydrogen peroxide were again added and the mixture was stirred for an additional 3 hours at the same temperature. The acid layer was separated from the hydrocarbon layer and the latter was extracted twice with 100 mi. portions of aqueous 5% sodium hydroxide and then with 100 ml. of aqueous 5% sodium bicarbonate. The hydrocarbon layer was then fractionally distilled at an absolute pressure of 22 mm. of mercury using a short distillation column, the 90% middle-cut being retained as the purified product. The purified methylnaphthalene was found to have a gum content of 0.15 %, which increased ro 0.31% after being subjected to an accelerated stability test as described below. In comparison, the unpurified methylnaphthalene had a gum-content of 0.100So which increased to 2.27% after being submitted to the same stability test. The impurities herein referred to collec tively as " gums " are those compounds which are readily adsorbed by hydrogenation catalysts and by microporous

materials such as activated alumina. The gumLcontents in weight percentages, based upon the weights of the methylnaphthalenes tested, were determined by adsorbing the gums on activated alumina in a chromatographic column, washing the column with methylene chloride to remove. hydrocarbons, eluting the gums with methanol and methanolic hydrochloric acid and then collecting the eluate, evaporating off the solvent and weighing the residue of gum. The accelerated stability test referred to above is carried out by adding 2.5 g. of aqueous 35% hydrogen peroxide to 25 g. of the methylnaphthalene being tested and then maintaining the resulting mixture at 100" C. for 24 hours while bubbling air at 2040 ml. per minute through the mixture. It has been found that the gum-content as measured after this test is a rough approximation of the stability of a methylnaphthalene against the formation of objectionable gums when the methylnahphthalene is used over a long period as a constituent of a working solution in a cyclic hydrogen peroxide synthesis process under normal conditions of operation, e.g. at temperatures which do not exceed 50 C. The accelerated stability test can also be applied to working solutions and the gum contents of the latter then determined as indicated above to provide a valuable indication of the stability of working solutions against gum formation during normal use. There was prepared a hydrogen peroxide synthesis working solution comprising 20% of 2-t-butylanthraquinone, 20 % of diisobutyl carbinol and 52% of the purified methylnaphthalene. The gum content of the working solution was 0.07% which increased to 0.35% after being subjected to the accelerated stability test described above. In comparison, a corresponding working solution prepared using the same methylnaphthalene in its unpurified state had a gum content of 0.02% which increased to 0.83% after the accelerated stability test. The hydrogenatabilities of the two working solutions were tested under identical conditions. In each case, hydrogen was passed at the rate of 1.5 litres per minute through 300 mi. of the working solution containing one gram of a palladiumzon-activated-alurnina catalyst containing 0.6% palladium while maintaining the mixture at 35 to 36 C. The rate of hydrogenation was observed by periodically determming the extent to which the butylanthraquinone was converted to the anthrahydroquinone. The working solution containing the purified methylnaphthalene hydrogenated at the rate of 0.130 mole of anthrahydroquinone per hour per litre of solution, whereas the rate for the working solution containing the unpurified methylnaphthalene was only 0.096 mole. EXAMPLE II.

A sample of commercial methylnaphthalene of petroleum origin was treated with performic acid then extracted with aqueous sodium hydroxide and aqueous sodium bicarbonate substantially as described in Example I. The hydrocarbon layer was then passed through a column of 48 to 100 mesh (Tyler Standard Sieve) activated alumina, the weight of the alumina used being equal to the weight of the hydrocarbon layer. The effluent purified methylnaphthalene had a gum content of 0.04% which increased to 0.12% after being subjected to the above accelerated stability test. EXAMPLE III. A sample of commercial alpha-methyl- naplithalene of coal-tar origin was purified by the procedure described in Example 2. The gum content of the purified product after it had been subjected to the accelerated stability test was 0.29% as compared will 1.71% for the purified material which had also been subjected to the accelerated stability test. What we claim is: - 1. A method of purifying a methylnaphthalene which is contaminated by impurities whose presence is objectionable in a working solution of the kind described, which method comprises treating said methylnaphthalene with an aliphatic peracid in the liquid phase and separating from said methylnaphthalene products of the reaction of said peracid with said impurities. 2. A method according to Claim 1 in which the peracid is formed in situ. 3. A method according to either of Claims 1 or 2 in which the products of the reaction of the peracid with the impurities are separated by fractional distillation. 4. A method according to either of Claims 1 or 2 in which the products of the reaction of the peracid with the impurities are separated by selective solvent extraction from the methylnaphthalene. 5. A method according to either of Claims 1 or Z in which the products of the reaction of the peracid with the impurities are separated from the methylnaphthalene by selective absorption on an adsorbent material. 6. A method according to Claim 5 in which the adsorbent material is activated alumina. 7. A method according to any one of Claims 1 to 6 in which the peracid contains 1 to 4 carbon atoms. 8. A method according to any one of Claims 1 to 7 in which the peracid is performic acid. 9. A method according to Claim 8 in which the performic acid is formed in situ by the reaction of hydrogen peroxide with formic acid. 10. A method according to any one of

Claims 1 to 9 in which said treatment is effected at a temperature of from 205 to 605 C. 11. A method according to any of Claims 1-10 in which the peracid is employed in an amount of from 2 to 25% based on the weight of the methylnaphthalene. 12. A method of purifying a methylnaphthalene substantially as hereinbefore described and illustrated by the foregoing examples. 13. A methylnaphthalene when purified by tile method of any one of the preceding

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