US2609794A - Piston type control valve for hydraulic presses - Google Patents

Description

P 1952 J. M. TOWLER ET AL 2,609,794

PISTON TYPE CONTRQL VALVE FOR HYDRAULIC PRESSES Filed May 24, 1946 3 Sheets-Sheet 1 2 I lnuenl or v M A Allorne Sept. 9, 1952 J. M. TOWLER ET AL ,7

PISTON TYPE CONTROL VALVE FOR HYDRAULIC PRESSES Filed May 24, 1946 5 Sheets-Sheet 2 F/GZ g E Inventor Sept. 9, 1952 J. M. TOWLER ETAL 'PISTON TYPE CONTROL VALVE FOR HYDRAULIC PRESSES Filed May 24, 1946 s Sheets-Sheet s :5 aka 5.

5 W m, m M N H h a mama-:45 xsn zma V V I fl fl 7 Patented Sept. 9, 1952 UNITED STATES PATENT :OFSFIHCE' John Maurice Towler, Harrogate, and Frank Hathorn Towler, Otley, England, assignors to Electraulic Presses Limited, Rodley, England, a corporation of England I *Application May 24, 1946, Serial No. 672,066

In Great Britain May 25, 1945 This invention relates to control valves for controlling the admission and exhaust of hydraulic liquid to and from a hydraulic press cylinder of the kind having means which prevent the valve from being operated to open the cylinder to full exhaust until thepressure in .the cylinder has fallen to a safe level thereby to prevent pressure surge in the hydraulic main due to sudden and full exhausting, and it isnan improvement in or modification of the valve according to our prior British Patent No. 524,564.

In the specification .of our prior patent we have described an anti-surge control valve in which an initial movement of the valve plunger gives a restricted or throttled release to exhaust and further movementto give full exhaust is resisted by a stop consisting of a small hydraulic ram which is subject to the pressure in the press cylinder: so thatmovement of the valve plunger to the full exhaust position isyprevented until the pressure in the press cylinder. has fallen to a safe level, when the operator can overcome the resistance of the opposing ram and'move the valve plunger over to the position of full exhaust.

The objectof the present invention is to provide an anti-surge control valve for hydraulic presses in which the movement of the valve plunger to the exhausting position is efiected by automatically operatingmeans.

Broadly a control valve according to the present invention is of the piston type in which movement of the valve plunger to open the press cylinder to exhaust is efiected by automatically operating means the complete movement of the plunger to the full exhaust position being prevented by automatically. operating stop means until the pressure in the press cylinder has fallen to a safe level as a result of a restricted opening of said cylinder to exhaust by theivalve plunger when in the position at which it is stopped by the automatically operating stop means.

The invention also contemplates a control valve as set forth above whereinmovement of the valve plunger in the opposite direction to admit pressure liquid to the press cylinder is effected manually by means that is operative on the-valve plungerinlthe one direction only.

. According to the present invention the valve plunger is-urged to the exhausting positions preferably by-a springbut'i'f desired by other alter- 3 Claims. (01. 121-465) 2 native means including hydraulic or pneumatic pressure or magnetically such as by the action of a solenoid. V.

In one practical application ofthe invention, the valve plunger is urged to the exhausting positions by aspring whichpresses against one end of the plunger whilst holding means consisting of a spring detent is providedto hold the operating handle in the neutral and pressure positions so that before exhausting can take place the detent must be overcome by the operator. When 7 the operator has overcome the resistanceof the detent the valve plunger is free tohmoveunder the influence of the spring into contactwith the hydraulic stop, in which positionrestricted exhaust commences, When the pressure has fallen sufiiciently for the spring to; push back the hydraulic stop the spring automatically completes the movement of the valve plunger to the full exhaust position. v 1 1 l The operating lever is operative in one direction only i. e.,.to move the valve plunger against the spring to. admit pressure liquid to the press cylinder. Movement :of the valve plunger in the opposite or exhausting .direction is effected wholly by the spring; Forthis purpose the operating lever may engage one .face of a single flange on the valve plunger through a fork, the .opposite face of the flange forming an abutment for the spring. 3 H

In order that the invention may be.clearly understood and carried into effect a practical example of the above embodiment 'willnow be described by aid :of the accompanying drawings in which: v.

Fig. 1 is a vertical section through the improved control valve takenon a line cuttingitransversely through the operating spindle.

Fig. 2 is a view similarto Fig. 1 but taken at right angles thereto. r

Fig. 3 is a diagrammatic view showing the association of the elements inthe operative assembly.

The improved. valve illustrated in the drawings is designed tofcontrol the admission of pressure liquid to and its exhaust from both. the main cylinder and one or more push-back cylinders of a hydraulic press and for. this purpose the body of the valve is provided with three connections numberedl, 2 .and 3. The connection .I .is. the pressure liquid inlet from the customary pumps,

the connection 2 for the transfer of liquid to and from the main press cylinder and the connection 3 serving similarly for the transfer of liquid to and from one or more push-back cylinders.

The above connections communicate with the interior of the valve bore 4 which consists of a parallel hole bored axially through the centre of a hardened steel bush 5 and lappedto provide a packingless sliding fit for the valve plunger ii. The plunger 6 is in. hydraulic balance both laterally and longitudinally. Lateral balance is obtained by providing annular grooves l, 8, 9 around the exterior of the steel bush 5 and connecting the connections I, 2 and 3 to saidgrooves by y passages H), H and i2 respectively in the valve body.

These annular grooves are spaced an equal distance apart in the lengthof the bush 5 and each communicates with the interior of the bore 4 by means, in each case, of a series of radial holes I3, 14 and iii. In the arrangementillustrated the connection 1 serving as the inlet the valve plunger. Operation of the valve plunger in the opposite direction to admit pressure liquid to the main hydraulic cylinder and exhaust it from the push-back cylinder(s) is effected manually by a hand lever 28. This lever is mounted upon an outer end of a spindle 29 and upon an intermediate portion of this spindle is mounted and fixedly secured a lever member consistingof a sleeve and a fork 3|, the latter being en- 'gageable-with the upper surface of the flange 21.

Opposing the upper end of the valve plunger for pressure liquid connect with the jmiddle V groove 8, the connection 2 from the main press cylinder'to the lower groove 9 and the connection-3 from the push-back cylinder(s) to the upper groove 1. a

The longitudinal balance of the valve plunger is obtained by ensuring that its two ends are open to spaces 16 and 11 which are maintained at equal pressure, preferably thatof the atmosphere, by means of passages '58 and K9 in the valve body which connect these two spaces together and said passagesin turn also communicate with a .main exhaustoutlet 29.

The distribution of "thehydraulic liquid by the control valve in consequence of longitudinal movement of the valve plunger is effected by an annular transfer passage '21 consisting of a'section of reduced diameter in the length of the plungerin conjunction with further reduced portions ,22 and 2 3 at opposite ends of the transfer passage and separated therefrom by portions 2e 7 and 25 of full diameter.

and at the same time to bring the reduced end portion 22 of the valve plunger into registration with the upper series of holes 13 thus permitting the push-back cylinder(s) simultaneously to exhaust by way of the upper space It and exhaust outlet 20. On the return or upward movement of the valve plunger the transfer passage 2! bridges the series of holes I4' and [3 thus permitting pressure liquid from the pump to how to the push-back cylinder(s) whilst at the same time the lower reduced portion 23 places the lower series of holes [5 in communication with the lower space H with the result that the main press cylinder is opened to exhaust.

The valve of the present invention is, however, an anti-surge valve and consequently incorporates means which prevents the valve plunger from being moved suddenly to the :full' exhaust position until the pressure in the main press cylinder hasfallen to a safe level. This desideratum is attained in the present valve by rendering the valve plunger manually operable only in the direction to open the hydraulic cylinder to pressure liquid, the movement in'the opposite direction to open the cylinder to exhaust being effected automatically by, for example, .a spring;

is a hydraulic ram 32 the cylinder 33 of which connects with the annular groove 9 by means of passages 34. When the valve plunger has been fully depressed, pressure liquid is permitted to pass from the annulus '9 to the cylinder 33 to act against the upper or piston end :of the ram 32, and in the neutral position of the valve plunger shown. in the tdrawings, this liquid :is trapped in the :cylinder. 33 thus converting the ram 32 into an immovable stop to prevent the completion of l. the upward movement of the valve plunger. The operating lever 23 is held frictionally in this :neutral position of the valve plunger and alsoin each of the pressure rde'livery positions by a spring detent consisting, in the illustrated example, of a spring pressed horizontal plunger 35, the outer end of which is formed with a heini-spherical projection that engages in turn in each ofthree correspondingly shaped depressions one of which is indicated at 3%, in the inside .face'of an extension piece 3'! on the boss of theoperatinglever.

In the operation ofjthe valve, the lever 2-8 when turned to the left eifects depression of the valve plunger through:co-action'between the fork 3i and the flange 21; This movement takes places against the upward pressure of the spring 28 and it results in the radial holes "M and I5 being bridged by the transfer passageil and pressure liquid flowing to the main hydraulic cylinder through the outlet connection :2. This downward movement of the plunger also results in the upper series ofradial holes 13 :being uncovered by registration therewith of the reduced portion 22, thereby permitting pressure liquid in the push-back cylinder(s) 'to -pa'ss into the space l6 and so toex-haust.

Immediately the operator releases the lever 23 from the hold of the detent :35 the valve plunger is moved upwards by pressure of the spring 26 and in so doingth'elever is itself automatically turned back to the neutral position shown where 'itjis held by. automatic. i e-engagement of the detent. .In; this neutral position the portions 24 and 25 on the valve plunger close the radial holes 13 and I5 and so look the pres sure, liquid-in the main hydraulic cy-linder. To exhaust this liquid requires a further upward movement of the valve plunger and this can only be brought about by freeing the same from the restraint imposed by the detentheld operating ever.

Therefore before the hydraulic cylindercanzbe exhausted the detentmust-again be 'over-' come and this requires a conscious eifort on behalf of the operator.

When the operator has overcome the detent he can leave go of the operating lever as the further movements of the valve plunger will then be performed automatically. On being thus released the spring 26 will forcethe valve plunger upwardsuntil. it comes into :contactwith the hydraulic? ram stop 32. .In this position of the valve, plunger a restricted exhaust of the press cylinder is permitted past the lower edge of the plunger portion 25 into the space I! but further upward movement of the valve plunger is prevented 'by the ram 32i During' such restricted exhaust, the valve plunger 6 has not moved sufficiently to interconnect the holes l3 and 14. As. howeven'a similar restricted escape of pressure from the ram cylinder is permitted in this position of the valve plunger the resistance of the ram to the further upward movement of the valve plunger will gradually reduce until it can be overcome bythe opposing pressure of the spring 26. When this condition is reached the pressure within the main hydraulic cylinder will have fallen to a safe level, so that the resulting final upward movement of the valve plunger and the opening of the hydraulic cylinder to full exhaust will produce no harmful pressure surge in the hydraulic main, and thereupon the holes I3 and M will be interconnected to direct pressure fluid to the push-back cylinders.

We claim:

1. A piston type control valve for hydraulic presses comprising a valve plunger slidable in a bore relatively to spaced openings for the pressure liquid, a transfer passage formed between the valve plunger and its bore for distributing the fiow of liquid selectively between said openings, in one extreme position to admit pressure liquid to an associated press cylinder and in the opposite extreme position to open said cylinder fully to exhaust, automatically operating means adapted to urge the valve plunger to the position of full exhaust, a hydraulic ram opposing said valve plunger in the direction of its movement to the position of full exhaust, means for admitting pressure liquid direct from the pressure cylinder to the back of said ram to hold the same in position to be contacted by the valve plunger in its movement towards and in advance of the position of full exhaust and to prevent the completion of said movement, said valve plunger acting when in said halted position to provide a restricted passage to the exhaust opening for the escape of pressure liquid from the press cylinder and from behind said hydraulic ram whereby the pressure in the press cylinder is permitted to fall to a safe level and the pressure on the ram also to fall until it can be overcome by the force urging the valve plunger to complete its movement to provide a full passage to the exhaust opening thereby to permit said movement to be completed and the press cylinder to be opened to full exhaust, manually operable means acting against said automatically operable means for effectively causing moving of the valve plunger in the direction to admit pressure liquid to the press cylinder, said manually operable means being operative on the valve plunger in the one direction only and inefiective for imparting movement to the valve plunger in the direction to open said cylinder to exhaust, although operable in a plurality of predetermined positions to restrict movement of said valve plunger in said last mentioned direction,

andaspring detent associated with the manual operablemeansadaptedto; hold the valve plunger seleictivelyinits neutral and pressure positions andhaving a holding force greater than that of 'saidzautomatical'lygoperating means and hence requiring to,:be:overcome by an action on the partofzthe operator before the valve plunger is nee-to move initherdirection of exhaust.

2; A piston ,typercontrol'valve comprising, in combinatiorria body having a valve bore with an exhaustopeningand with port openings arranged in axially spaced relation, of which a first port opening-.is adapted for connection to a source of pressure fiuid' andfai second port opening is adapted for connection to a fluid operated unit, a valve plunger slidable in said bore and axially adjustable therein, said plunger having a first position in which it interconnects the first, and second port openings, and being movable in one direction out of said first position successively into a second position in which it interrupts communication between the first and second openings and effects a restricted interconnection between the second port and third openings, and an exhaust position in which it enlarges the communication between the second port and exhaust openings, means for biasing said valve plunger with a given force for movement in said one direction, a cylinder adapted for connection to receive and exhaust fluid in common with the second port opening, a stop member operatively disposed in said cylinder and responsive to the pressure fiuid therein to project therefrom for abutting engagement with said valve plunger whereby to restrict said plunger to said second position in opposition to said biasing means, a manual actuator for shifting said valve member in the opposite direction against the force of said biasing means into said first position, and releasable detent means for holding said valve plunger in said first position, said detent means having a holding force greater than said biasing means so as to necessitate manual operation of said actuator in said one direction to initiate movement of said valve member out of said first position for movement by said biasing means into said second position.

3. A piston type control valve comprising, in combination, a body having a valve bore with an exhaust opening and with port openings arranged in axially spaced relation, of which a first port opening is adapted for connection to a source of pressure fiuid and a second port opening is adapted for connection to a fiuid operated unit, a valve plunger slidable in said bore and axially adjustable therein. said plunger having :a first position in which it interconnects the first and second openings, and being movable in one direction out of said first position successively into a second position in which it interrupts communication between the first and second openings, a third position in which it effects a restricted interconnection between the second port and exhaust openings, and a fourth position in which it enlarges the communication between the second port and exhaust openings, means for constantly biasing said valve plunger with a given force for movement in said one direction, a cylinder adapted for connection to receive and exhaust fluid in common with the second port opening, a stop member operatively disposed in said cylinderand responsive to the pressure fiuid therein to project therefrom for abutting engagement with said valve plunger whereby to restrict said plunger to said third position in opposition a 7 to said biasing means, a. mammal actuator vfor REFERENCES CITED shifting said valve member in'the opposite :direo- The following references are of .recordm the tion against the force of said biasing means into -fi1 t Patent; 7 said first position, and releasable detent means r v for holding said valve plunger in :said *second 5 T UNITEDSTATES PATENTS position, said detent means having a holding Number] V Name 7 7 Date force greater than said biasing means-50 2s to 2,239,139 .Allin Apr. 22, 1941 necessitate manual release of-said actuator'inlthe 2,335,809 Stacy "Nov. 30, 1943 said one direction to' initiatemovement-of said 2,362,864 Towler' Nov. .1-4, 1944 valve member :out :of said second position for 10 2367-241 Stacy Jan. 16, 1945 Ipigglililrfnt by said n biasm'g'meansinto said third 7 FOREIGN PATENTS JOHNMAURICELTOWLER. V- e Country I Date FRANK HATHORN"'EOWBER 524,564 Great Britaini;.s i Aug. .9, 1940

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