US2644429A

US2644429A - Hydraulic control device

Info

Publication number: US2644429A
Application number: US4256A
Authority: US
Inventors: Waterman William; Donald A Stark
Original assignee: WATERMAN
Current assignee: WATERMAN
Priority date: 1948-01-26
Filing date: 1948-01-26
Publication date: 1953-07-07
Anticipated expiration: 1970-07-07

Description

i y 7, 1953 w. WATERMAN ETAL 2,644,429

HYDRAULIC CONTROL DEVICE Filed Jan. 26, 1948 2' Sheets-Sheet l MQSZL r& a} We July 7, 1953 Filed Jan. 26, 1948 W. NATERMAN ETAL HYDRAULIC CONTROL DEVICE waxy 2 Sheets-Sheet 2 i v the-plane 2- 2 of Fig. 1;"

Patented July 7, 1953 jUNiTsD, STAT B EATENT oFF cEJ HYDRAULIC ooN'rRoL} DEYICEH William Waterman, Chicago, Donald A. I .S'tark, Willoughby, OhioasaidiStark assignor I to said Waterman a v AppIication'JaniIary' ZG, 1948, Serial No 4,256 7 =4 Claims.;.(Cl. 121-465) This invention relates to hydraulic control de viceshand particularly to valve devicesfor conitrolling supply of hydraulic fluid to'and discharge thereof from, an instrumentality wherein th'eldis charge pressures may be'high.

Among other objects, the invention aims'to provide safety means under the control of the valve device for safely and easily effecting thedis charge of high pressure fluid. l Another object is to' provide separate means unde'r'tlie control or the valve device for assum ingand holding, without leakage, high pressures and'fo'r relieving the valve device of this function."

A further 'object i's 'to' pr'ovide a control unitwhich in addition to' the foregoing functions; is adapted independently to control the rate of supply and discharg'eof hydraulic-fluid.

'Z-Other objects and: advantages of the invention will'becom'e" apparent from the fol-lowing descrip- 3 tion" of one illustrative device embodying the invention and showri'in the accompanyingclrawing's. v

Insaid drawings: I g; 1" is a planvie'w of'the'device; F'ig .'=2 isa side elevation thereof, taken trohi The uses of hydrauliclifting and other rams" arevaried. One common use is for lift trucks wherein the load elevated-by the ram maybe. very heavy and :must often be held in elevated position during themovement of the truck, and

often for substantial periods of time. The valve device is not, however, limitedin itsuseto rams but maybe employed wherever similar functions are required. For conveniencethe'term-ram= will be employed infa broadisense to designatethe operating instrumentality; controlled by. the

valve device.

' The three wa yv operation of the illustrativevalve devicelfl is-efiected in this'" instance-by a longitudinally slidable spool-type valve member 2 (operated as presently: described), to the valve chamber 22 of which supply-from pump [3- is ad-;

- mitted through port 23. A spool type valve'is Fig. 3 'is' a plan section" takenon the-plane L JFig. 4'15" anend e16vatio of the device ;-tai;e

from the planel -i-ll OfFi'gz-l;

. Fig. 5 isa view similar to that cr me that being'partly' sectioned on the plane 5 501? Fig. 4;

6 is an -end view (inverted relative to Fig.

3),"partly sectioned 'on'the plane of Fig to'illustrate tlie flow regulator.

. Fig. 7 ista diagramof a system runction and" operation of the "valve d s hydraulid-rams-and thelike; and

Fig.8 isa fragmentary section on are as-ea scale of the pilot controlled OhQOk VElIIVQ S hQV Iil also in Fig. 3. v

In hydraulic cylinders operating against a continuous force or load, the illustrative valve device'l 0 operates to control delivery of pump pres sure to the single acting ram cylinder l l- (Fi'gl'?) The ramis held elevated or in extended position against the-load by's'eparate means capable of holding pressures created by the load or otherwise, Without leakage, thereby in effect, locking the ram against downward or return creeping movement. The valve device thus has utility in hydraulic rams for lifting trucksand' other apparatus; The valve is. also adapted to comm to illustrate the advantageousbecause itmay be balanced for easy operation, but it characteristically leaks andis therefore incapable-foil holding a ram against; creepingor;slowcreturntravel. The aforesaid valve chamber communicates "with passage' -z i' leading (as presently described) to the ramand toinletpjort 25.0fline25 leading to'the' reservoir 1 by throttling: port 25, thereby. controlling the speed of rain travel.v The balance of the pump flow by-passesto thereservoir.

Line 139 leading toram cylinder l I is connected to valve block 3| at fitting 32 (Fig. 6). The latter apassage orborett extending longitudinally or the'valve block and closed at one end by a'plug. Passage 33 communicates'with passage ZQthrough a; cylindrical recessor socket 34 in the valveblock .in which isseated 'c'heck'valve unit 35 functioningto permit travel 'of fluid from the spool to passage 33 and the rain, but blocking return travel descent. of theram underitsownload or weight; w

and when fully descended-, the valve discharges 'or by-passesthe pump l3;.into reservoir "H at practically no load.

in turn communicates as presently described with from the ram'tojthespool. Spring 31 prevents displacement of check-"ball 36-relative to its seat" 38 regardless of the position of the device. Checkvalve unit 35 is sealed recess 34 by sealing rings 39,land held therein" against "the bottom of the recessiby screwplug w. =F luid enters thecheck valve unit through chamber 4| (in communication with passage 24) and leaves through the annular passage 42 around the unit which communicates with passage 33.

The latter passage also communicates with a check valve unit 43 which functions when closed, to lock the ram in elevated or extended position underload, thereby relieving spool 2| and its operating mechanism of the very substantial load of the ram and avoiding leakage around the spool which would otherwise ensue. Since check valve prevents return flow from the ram through passage 24, the ram is held stationary in its extended position until opening of check valve unit 43.

The latter valve unit is advantageously seated.

in the cylindrical recess 45 located in the valve block so as to be intersected by bore 33, and is sealed therein by sealing rings 46 and held tightly against the bottom of the recess by a screw plug 41. The valve comprises a cylindrical shell 48 at the end of which is a valve seat 49 and port 5| communicating with the space 52 at the bottom of the recess which in turn communicates with passage 53 leading to the spool bore 54. Discharge from the ram passes from the annular space 55'around the valve body (in communication with passage 33) through a series of holes 56 in the valve body through port 5| and thence through the spool cylinder to discharge port 51 openinginto discharge line 26. The latter port may be closed by the enlarged portion 58 on the spool and may be throttled to vary the rate of descent of the ram at the will of the operator, by the tapered portion 59 on the spool.

Port 5| is closed by check valve 6| here shown with a hollow cylindrical body provided with a valve tip 62 adapted to seat on seat 49 and close port 5|. The valve is held against its seat by the back pressure in line 33 which communicates with the interior of the valve' through a restrict ed port 63(Fig. 8).-

The-check valve also embodies a pilot valve 65 here shown in the formof a ball adapted to seat and. close a small port 66 in the tip of valve 6|. The ball is held on its seat by a'cylindrical fluid andtherefore substantially balanced. 'A

relatively light spring seat.

Though valve 6| is held on its seat by a substantial unbalanced force created by the pressure fluid on the interior of the valve, the pilot valve 65 may be unseated with little force. In the present instance, the pilot valve is unseated by a pin '12 whose restricted end 13 passes through port 66 and is adapted to engage the ball. Pin 12 is operated by the cam surface 14 upon longitudinal movement of the spool. When ball 65 is thus unseated, 'fiuid pressure inside the valve may exhaust through port 66 into return line 53 at a rate much faster than fiow of pressure fluid into the interior of the valve through the restricted orifice 63. The result is that the pressure drop inside the valve is sufiiciently great to be overbalance'd by the pressure of the fluid against'the annular end 16 of the valve around port 5|. Valve 48 thus opens and connects line 33 from the ram with the passage 54 leading 1| holds the ball on its to discharge port 51. The tapered portion 69 on the spool is so located in relation to the cam surface 14 that after the pilot valve is opened, the tapered portion 59 on the spool may be employed to throttle discharge port 59 and thus regulate the rate of descent of the ram.

Maximum rate of descent is advantageously limited by interposing in line 33 a regulator valve 11 (Fig. 6). The regulator valve is adjusted to limit the rate of descent of the ram to a safe speed regardless of the load on the ram. For

light loads or no load, the rate of descent of the ram is equally rapid since the valve automatically adjusts itself to permit a constant rate of discharge. For descent at a rate less than the .maximum rate, the spool is adjusted to throttle orifice 51 by means of the tapered portion 59 on the spool as aforesaid.

The illustrative regulator valve comprises a hollow cylindrical member 18'slidab1e inside the body of the valve and having an inlet orifice l9 communicating with line 30 leading from the ram and adapted to create a pressure drop tending to move the valve member 18 in the direc-- tion of flow. Flow from the regulator valve occurs through ports 8| throttled by themovement of valve 18 against the spring 82. Ports 8| communicate with the annular space 83-. around the valve which in turn communicates with passage 33 leading to discharge For-high pressures, the pressure drop in orifice l9'is sumcient to cause a greater throttling of ports-8|: than for the lower pressures existing .when the ram is only lightly loaded. Conversely, for lighter pressures, a greater port opening is re-: quired to permit the pressure drop "necessaryto counterbalance spring .82,?which accordingly moves the valve toincrease the port opening. As here shown the valve is seated in a transverse bore 84 in the valve block in'which it is sealed by sealing rings 85 and heldmy: lock ring-86. The bore is intersected by bore33'. While the illustrative regulator (these details are fully disclosed in our co-pending application) is simple and inexpensive in construction and well adapted for incorporation in the valve block; in;asso-- ciation with the several control elements, it will be understood that the invention is not limited to the specific type of regulator herein disclosed.

The illustrative valve device thusembodies in one unit control means by which the ram is elevated and permitted to descend at rates-determined by the operator while avoiding descent at unsafe speeds or slow descent with light loads,

together with devices for positively locking-the ram in extended position under load andrelieving the control device of such load and preventing leakage and creeping of the mm which would otherwise occur.

The spooloperating mechanism is'here shown in the form of a control rod 81 longitudinally slidable in the body of the valve block parallel to spool 2| to which it is connected by the transverse yoke 88.

Stops

89 and 90 limit the movement of the control valve, and therefore the spool, in both directions. Neutral position of the spool (wherein the pump discharges at no load) is advantageously easily located and held against accidental displacement by a catch here shown in the form of a spring pressed ball, 9|j adapted'to seat in a notch 92 in control 'rod The faces of notch 92 are advantageously beveled or tapered to openv the catch when the control rod is purposely moved. The end of the'control rod is advantageously threaded as at 93 for attachment of an appropriate operating handle or other mechanism.

Obviously the invention is not limited to the details of the illustrative device since these may be variously modified. Moreover it is not indispensable that all features of the invention be used conjointly since various features may be used to advantage in different combinations and sub-combinations.

Having described our invention, we claim:

1. A control unit for a ram and ram cylinder wherein the load on the ram tends to return the latter to initial position comprising in combination a valve housing having therein a valve chamber and passages leading to said valve chamber and adapted to be connected respectively to the ram cylinder, to a source of fluid pressure, and to discharge; a throttling control valve in said chamber adapted selectively to connect the pressure source with the ram cylinder passage and with the discharge passage, said control valve having means for adjustably throttling flow from said ram cylinder to discharge, a check valve in said ram cylinder passage to prevent return flow from said ram cylinder through the latter passage, a by-pass around said check valve and leading to said valve chamber, a by-pass check valve in said bypass having means actuated by said control valve to open said by-pass check valve, the latter valve being normally closed to flow from 'said ram cylinder through said by-pass, and means for operating said control valve to open said bypass valve to connect said ram cylinder to discharge.

2. A control unit for a ram and ram cylinder wherein the load on the ram tends to return the latter to initial position comprising in combination a valve housing having therein a valve chamber and passages leading to said valve chamber and adapted to be connected respectively to the ram cylinder, to a source of fluid pressure, and to discharge; a balanced throttling control valve in said chamber adapted selectively to connect the pressure source passage with either ram or discharge passages, said control valve being adjustable to open said discharge passage fully to permit unrestricted discharge of fluid from said pressure source at no load, a check valve in said ram cylinder passage to prevent return flow from said ram cylinder through the latter passage, a by-pass around said check valve and leading to said valve chamber, a bypass check valve in said by-pass having means actuated by said control valve to open said bypass check valve, the latter valve being normally closed to flow from said ram cylinder through said by-pass, said control valve having means for variably throttling flow passing from said bypass check valve to discharge.

3. A control unit for'a ram and ram cylinder wherein the load on the ram tends to return the latter to initial position comprising in combination a valve housing having therein a valve chamber and passages leading to said valve chamber and adapted to be connected respectively to the ram cylinder, to asource of fluid pressure, and to discharge; a balanced control valve slidable'in said chamber and adapted selectively to connect the pressure source passage with the ram cylinder passage or discharge pas= sage and to connect said ram cylinder to discharge, a check valve in said ram cylinder passage to prevent return flow on said ram through the latter passage, a by-pass around said check valve and leading to said valve chamber, said control valve being freely slidable in said chamber, and susceptible to leakage under ram cylinder pressures, a by-pass'checl; valve in said by-pass normally closed to flow from said ram cylinder, thereby relieving said control valve of ram cylinder pressure, said by-pass check valve having a pilot actuating valve provided with means engaged by said control valve for opening the pilot valve and thereby opening said by-pass check valve, said control valve having means for adjustably throttling said ram cylinder passage to control the rate of return of said ram, and means for actuating said control valve.

4. A control unit for a ram and ram cylinder wherein the load on the ram tends to return the latter to initial position comprising in combination a valve housing having therein a valve chamber and passages leading from said valve chamber to the ram cylinder, to a source of fluid pressure, and to discharge; a balanced control valve slidable in said chamber and adapted selectively to connect the pressure source passage with the ram cylinder passage or discharge and to connect said ram cylinder passage to discharge, a check valve in said ram cylinder passage to prevent return flow on said ram through the latter passage, a by-pass around said check valve and leading to said valve chamber, a by-pass check valve in said by-pass normally closed to flow from said ram cylinder and through said by-pass, said bypass check valve having a pilot actuating valve having means engaged by said control valve for opening the pilot valve and thereby opening said by-pass check valve, said control valve having means for adjustably throttling said ram cylinder passage to control the rate of return of said ram, and a regulator valve for the flow through said by-pass for limiting the maximum flow therethrough thereby to limit the maximum return speed of said ram.

WILLIAM WATERMAN. DONALD A. STARK.

References Cited in the flle of this patent UNITED STATES PATENTS Number Name Date 715,009 Brindley Dec. 2, 1902 752,780 Johnston Feb. 23, 1904 1,804,137 Yates May 5, 1931 1,995,052 Bodenlos Mar. 19, 1935 2,377,278 Stephens May 29, 1945 2,418,325 Wassall et a1. Apr. 1, 1947 2,430,197 Wells et al. Nov. 4, 1947 2,482,249 Court Sept. 20, 1949