US2887990A - Lift cylinder regulator valve - Google Patents

Description

May 26, 1959 R. E. ROGERS LIFT CYLINDER REGULATOR VALVE Filed June 1. 1954 4 Sheets-Sheet 1 lnven tor W a62 19M,

Attorney y 1959 R. E. ROGERS 2,887,990

LIFT CYLINDER REGULATOR VALVE Filed June 1,1954 I 4 Sheets-Sheet 2 Inven tar l ttofney y 6, 1959 R. E. ROGERS 2,887,990

LIFT CYLINDER REGULATOR VALVE Filed June 1. 1954 4 Sheets-Sheet 3 I I I a I L v I Q l WI I L M Nik LIME 'l "W W m we I I i1 if: I

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LIFT CYLINDER RECULATORVALVE Filed June 1, 1954 v 4 Sheets-Sheet 4 a I N g; Q a J 7 i "I g Q i 3 E? i nuumm l g N H E g? 25$ United States Patent I 2,887,990 LIFT CYLINDER REGULATOR VALVE Richard E. Rogers, Racine, Wis., assignor to J. I. Case Company, Racine, Wis., a corporation of Wisconsin Application June 1, 1954, Serial No. 433,353

' Claims. (c1. 121-ss) The present invention relates to hydraulic loaders and the like and particularly to the hydraulic portion of machines of this type, and an object of the invention is to generally improve hydraulic loaders and particularly the hydraulic mechanism of such machines.

More particularly the invention relates to hydraulic actuating devices of relatively large capacity and to expedients which facilitate the control of such hydraulic mechanism for more eflicient operation and also which reduce the size, weight, and cost of such devices.

In a device such as a loader, shovel, or the like, very substantial weights have to be lifted by the hydraulic cylinders involved and conversely, at times it is. desirable to be able to force the shovel downwardly, as when attempting to dig into hard ground. For the first purpose, in order to avoid excessive pressures in the apparatus, it is necessary to have a cylinder or cylinders of relatively large area or capacity in order to get the necessary force in the lifting action. Also the pump must be of limited capacityin order to avoid overloading the driving means. In a double acting circuit such as this it is commonly necessary :for all of the fluid, for whichever end of the cylinder it is destined, to pass through the pump. However, when it is desired to lower the shovel, the load in the shovel (and in fact probably the weight of the shovelitself) is ample to force the piston rapidly to one end of the cylinder. In fact, if the usual controlvalve is shifted into lowering position, the fluid in one end of the cylinder will be very rapidly discharged into the reservoir by the action of the load, while the other end of the cylinder, receiving only the output of the pump, will be insufiiciently supplied with fluid, and a partial vacuum will be created in the opposite end of the cylinder which, as is well known, is undesirable. Furthermore, this sudden rush .offluid intothe reservoir, will be greatly in excess of thecapacity of the pump to remove fluid from the reservoir, and'as a result the reservoir may overflow unless it is of a capacity greatly in excess of what is actually needed for the operation of the lift cylinder.

It will be apparent that, if the fluid coming from the discharging end of the cylinder could be transferred immediately to the opposite end of the cylinder, both of these difliculties could be avoided; the reservoir would not be overloaded and nopartial vacuum would be formed in the receiving end of the cylinder. This suggests a bypass from one end of the cylinder to the other, but of course any such connection would defeat thepurpose of the'cylinder unless it were properly con- "trolled, and accordingly it is another object of the ini the accompanying drawings, in which-- Figure 1 is a right side elevation of a tractor with 2,887,990 Patented May 26, 1959 2 the device of the invention installed thereon, parts being broken away to show what lies beneath.

Fig. 2 is an enlarged partly diagrammatic view of the complete hydraulic circuit showing the reservoir and pump in symbols, the valve in axial section and the ram orcylinder in side elevation with parts broken away.

Fig. 3 is an enlarged vertical axial section of the head end of the cylinder shown in Fig. 2.

Fig. 4 is a horizontal section on the line 44 of Fig. 3.

Figs. 5 and 6 are views showing a fragment of Fig. 3 with the parts in different positions, the cylinder being added in diagram.

Similar reference characters have been applied to the same parts throughout the drawings and specification, and it is understood that these illustrations are not to be taken as limiting the invention but are illustrative merely.

In the drawings Fig. 1 represents atractor generally designated as T having a frame F, a traction wheel W, a front wheel W and the usual components, unnecessary to describe in detail at this point, but which will be described wherever they affect the invention. 7 Frame F has an upright 10 on which is journaled at 12.an arm 14 of such character and strength as to be capable of carrying a shovel or scoop 16 for digging into the A linkage genearth, a pile of material, or the like. erally designated as 18 is utilized for controlling the angle of scoop 16 but, forming no part of the present invention, need not be further described.

Arm 14 is raised and lowered about pivot point 12 by means of a hydraulic ram or cylinder generally designated as 20, in the present instance comprising a cylinder 22 pivoted to frame F at'24. A piston rod 26 extending from cylinder 22 is pivoted at 28 to a plate 30 permanently united with arm 14. From the above it will be apparent that extension of piston rod 26 will cause counterclockwise swinging of arm 14 about pivot 12 and raising of shovel 16. Conversely, retracting of rod 26 will cause clockwise rotation of arm 14 and lowering of shovel 16.

It will also be apparent. that the very substantial weight of arm 14 and shovel 16 will continuously tend to force rod 26 into cylinder 22, or bias the ram toward retracted position.

In apparatus of this kind it is sometimes desirable to apply downward pressure on shovel 16, for example, to force it into hard ground, the weight of the parts at times being insufiicient. This can be accomplished in a manner in which it will appear.

It is contemplated that the mechanisms illustrated may be duplicated on the opposite side of the tractor without departing from the invention, thus utilizing the combined power of two rams instead of one, but since the rams are identical it will be necessary to describe only one.

Fluid for. actuation of ram 20 is obtained from a reservoir 32 in the present instance carried on the ,transmission and rear axle housing 34 of the tractor and in which isarranged a pump 36 driven by a power take-olf-shaft 38 actuated from the tractor mechanism in well-known manner, pump 36 raising fluid through a suction pipe 40 and delivering it through a pipe 42 to a valve generally designated as 44 from which the fluid is directed through pipes 46 and 48 alternatively to the desired end of cylinder 22, fluid exhausted from cylinder 22 being returned from valve 44. to reservoir 32 through a pipe 50. It will now be apparent that proper manipulation of valve 44 will cause extension or retraction of ram 20 and raising or lowering of shovel 16. It will also be apparent that the speed of operation of ram 26 for any given speed 3 of pump 36 will be a function of the ratio of volumetric capacity of the cylinder 22 and the pump 36.

Turning to Fig. 2, valve 44 may be of any suitable or well-known type which will bypass the fluid from pump 36 when in one position, when in another position will direct fluid to one end of cylinder 22 through pipe 46, and when in another position will direct fluid to the other end of cylinder 22 through pipe 48, in each instance allowing exhaust fluid to return through the opposite pipe and directing it to reservoir 32 through pipe 50. In fact it is contemplated that other hydraulic circuits may be used insofar as the invention is concerned provided that they are adapted to direct pressure fluid to one end of the cylinder and exhaust fluid from the other end under control of an operator.

In the illustrative embodiment, valve 44 has a body 52 in which is slidable a spool or plunger 54 having a series of grooves 56, 58, and 60. In the position of the parts shown, fluid from pump 36 coming through pipe 42 enters a bore 62, and encounters the land 64 between grooves 56 and 58. Blocked from further progress in this direction, it flows through a passageway 66 into groove 60, and, through a portion of bore 66 in which plunger 54 slides, to a passageway 68, and thence through pipe 50 to reservoir 32. The several pipes and passageways being of ample capacity, pump 36 operates freely and against no substantial resistence while the parts are in this relation. Shifting of plunger 54, for example, by means of a handle 68 fixed on a lever 70 pivoted at 72 to plunger 54 and having a fulcrum bearing 74 to the right, will first of all by means of land 76, block passageway 66 and thereby stop the flow of fluid into passageway 68. This will cause a virtually instantaneous pressure rise in pipe 42 in well-known manner, the usual safety expedients not shown being provided to avoid excessive pressure and damage therefrom. Such shifting of plunger 54 will also shift land 64 thereby connecting passageway 62 with a passageway 78 leading to and connected with above-mentioned pipe 46. The pressure fluid is therefore free to travel through groove 56 to pipe 46 and thus to one end of cylinder 22. This will cause actuation of a piston 80, to the right as seen in Fig. 3. Fluid onthe right side of piston 80 will find its way in a manner to be presently disclosed into pipe 48, thence to a passage- Way 82 and into groove 58 which has also been shifted by reason of the shifting of plunger 54 so as to register with a passageway 84. Passageway 84 connects with a passageway 86 which in turn connects with above-mentioned passageway 68. Thus, fluid from the right end of cylinder 22 passes through pipe 48, passageway 82, groove 58, passageways 84, 86, and 68 to pipe 50 and is returned to reservoir 32.

When shovel 16 has reached the desired height, handle 68 is released and a centering device of well-known form, generally designated as 88, returns plunger 54 to the position shown; whereupon, passageways 78 and 82 are blocked by solid portions of plunger 54 from communication with passageways 90 and 84, and groove 60 is again in position to permit bypass of the fluid coming from the pump 36. Shovel 16 is quite heavy and tends strongly to return piston rod 26 toward the left end of cylinder 22, the cylinder and piston acting as a pump and tending strongly to force fluid back through pipe 46 and passageway 48. When it is desired to lower shovel 16, plunger 54 is shifted to the left whereupon the reverse of the action just described takes place, fluid exhausting from cylinder 22 through pipe 46, passageway 78, groove 56, a passageway 90 connected with above-mentioned passageway 86, said passageway 86, passageway 68 and pipe 50 to reservoir 32. In like manner a land 92 on plunger 54 blocks passageway 68 and pressure fluid from pump 36 passes through pipe 42, passageway 62, groove 58, passageway 82 and pipe 48 to the right end of cylinder 22. Unless care is exercised in the amount of shifting of plunger 54, this action can be much more rapid than the raising action, the fluid flooding the reservoir 32 faster than pump 36 can remove it and also the pump failing to supply fluid rapidly enough to fill the right end of cylinder 22. Furthermore, in the interests of efliciency of shovel 16, it is not desirable to limit the lowering speed except to stay within the limits of safety. To thus increase the efliciency and to avoid the difficulties mentioned, pipes 46 and 48 are connected, not to the respective ends of the cylinder directly, but to a metering and bypass valve unit generally designated as 94, unit 94 having a branch pipe 96 which connects, through a fitting of well-known type 98, with the right end of cylinder 22, unit 94, generally speaking, connecting pipe 46 with the left end of cylinder 22 and pipe 48 with the right end of cylinder 22.

Unit 94 under certain conditions, as will be explained, serves to bypass fluid directly from the left end of cylinder 22 through pipe 96 to the right end of cylinder 22, thus preventing such fluid from reaching reservoir 32 and also supplying ample fluid to keep the right end of cylinder 22 supplied so as to avoid the forming of a vacuum.

Turning now to Figs. 3 to 6, Figs. 3 and 4 show unit 94 in detail, the same comprising a body portion 100 preferably bolted in place on the head 102 of cylinder 22 as by cap screws 104 engaging ears 106. Body 100 has a longitudinal bore 108 in the present instance providing an internal shoulder 110. A sliding valve 112 in the present instance in the form of a sleeve,- is arranged in substantially fluid tight relation in bore 108 and in one position serves to bypass cylinder 22, or in effect connect pipe 46 with pipe 96. Most of the time, however, sleeve 112 is in the position shown in Figs. 3 and 5, pressed down against a portion of head 102, in part by a spring 114. Sleeve 112 has a seat 116 against which is pressed by a spring 118 a ball or check valve 120, and sleeve 112 extends across and :blocks a port 122, so that fluid coming in through pipe 46, as shown in Fig. 5, passes through seat 116, pressing ball 120 out of the way and proceeding downwardly through a passageway 124 into cylinder 22, spring 118 being light, no objectionable resistance to fluid flow is set up by ball valve 120. Sleeve 112 extending across port 122 in this position, excludes pressure fluid from port 122 and pipe 96.

Spring 118 is supported in the bore 126 of sleeve 112 in the present instance by means of a spider 128 pressing against a snap ring 130 suitably engaged in the wall of bore 126.

When the lifting motion is stopped, spring 118 returns ball 120 to its position against seat 116 and the parts remain in this condition. When it is desired to lower the shovel, the action illustrated in Fig. 6 takes place.

First, pressure is released from pipe 46 and fluid starts to flow outwardly through passageway 124. It cannot get past ball valve 120, so a pressure differential is set up with the higher pressure beneath sleeve 112, a series of outlet ports 132 being blocked by the portion of bore 108 below shoulder 110, as seen in Figs. 3 and 5. If the shovel is to be lowered slowly so that only a slow flow is allowed from pipe 46 sleeve 112 will be raised, compressing spring 114 only sufficiently to allow escape of some fluid through ports 132 into bore 108 above shoulder 110, this fluid finding its way to pipe 46 directly through a bore 134 or a series of ports 136 or both. At the same time a sufficient quantity of fluid will be supplied through pipe 48, a bore 138 and a bushing 140 to above-mentioned pipe 96 to supply the right end of cylinder 22.

On the other hand, if shovel 16 is to be lowered rapidly the clearance of sleeve 112 above shoulder 110 is insuflicient to accommodate the large volume of fluid. Sleeve 112 is therefore lifted to the position shown in Fig. 6, clearing port 122, whereupon a large volume fluid may flow through port 122, a passageway 142, forcing a ball valve 144 away from a seat 146 and passing without substantial resistance past aspider 148 and through a bore 150 in above-mentioned bushing 140.

Spider 148 seats against a portion of bushing 140 and supports a spring 152 which serves to urge ball 144 against seat 146. -In this Way ample fluid is supplied to the right end of cylinder 22, in spite of any deficiency in the flow coming in through pipe 48. In fact the flow through passageway 124 will be in excess of the requirements of pipe 96 because of the displacement of the piston rod 26. There will, therefore, be more fluid flowing out through ports 132, 136, and 146 than there is flowing through passageway 142, this difference amounting to the displacement of the piston rod plus the capacity of pump 36. The capacity of ports 132 is therefore preferably graduated or predetermined along with the clearance between sleeve 112 and bore 108 so that this excessive volume of fluid can flow through and will cause raising of sleeve 112 at such times as the demands of the right end of cylinder 22 exceed the capacity of pump 36.

The exact construction of unit 94 may be varied within the contemplation of the invention but in the present instance a packing in the form of an O ring 154 serves to seal the joint between body 100 and head 102. Also where pipe 96 enters bushing 140, the pipe is reduced slightly as at 156 and an O ring 158 enclosed in a suitable groove in bushing 140 engages the reduced portion to form a fluid tight seal. In this Way, a fluid tight connection is achieved without careful fitting of pipe 96 between unit 94 and fitting 98 and, in the event of unequal expansion of cylinder 22 and pipe 96, portion 156 may freely move within bushing 140 without destroying the seal.

When it is desired to force shovel 16 downwardly, fluid from pump 36 enters unit 94 through pipe 48, passing through bore 138, past spider 148 and into pipe 96, valve 144 remaining on the seat 146 as seen in Figs. 3 and 5. Under these conditions, however, the movement of piston 80 will be slow, sleeve 112 will normally be raised only sufficiently for ports 132 to clear shoulder 110 and port 122 will be blocked by sleeve 112, which will not have moved far enough to uncover it. In this case the pressure in bore 138 will be greater than that in bore 108 or sleeve 112, so that there will be interchange of fluid from one end of the piston to the other, even if sleeve 112 should for some reason move further than contemplated.

It is thought that the operation of the device will be clear from the foregoing description, sufiicient to say that ram 22 is under the control of valve 44, and that when rapid lowering of the shovel or load imposed upon ram 22 is desirable, the fiuid from the exhausting end of the cylinder is automatically bypassed to the opposite end, augmenting the supply from the pump to avoid a partial vacuum and also disposing of the fluid to avoid overloading of the reservoir.

To compensate for the weight of shovel 16 and its attached parts and contents and avoid loss of traction, a ballast unit or weight box of well-known type 160 is supported rearwardly of the tractor on a platform 162 suitably braced by a strut 164.

The above being a complete description of an illustrative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a pressure fluid actuated motor of the type comprising a cylinder, a piston slidable within the cylinder for performing useful work and yieldingly urged in one direction, a first fiuid conducting conduit communicating with the cylinder on the side of the piston toward which the piston is urged, a second fluid conducting conduit communicating with the cylinder on the side of the piston away from which the piston is urged, means for alternatively supplying pressure fluid to either conduit and exhausting it from the other, a bypass passageway opening out of said first conduit and connecting the first and secmains across in closing relation with said bypass passagewayI I 2. A bypass valve for a power lift cylinder of the type in which fluid may be introduced on either side of the piston to provide movementin either direction, 'said' valve comprising a body portion, a passageway leading through the body portion into one end of the cylinder, a fluid conduit leading into said passageway, a passage way transverse to the first-mentioned passageway and leading to the other end of said cylinder, a sleeve valve slidable in the first-mentioned passageway extending across the second-mentioned passageway so as to prevent passage of fluid from one passageway to the other, a check valve seat within the sleeve valve, a check valve element resiliently pressed against said check valve seat in a direction away from said cylinder, said sleeve valve being resiliently biased toward said cylinder, said first-mew tioned passageway having an enlarged portion extending in a direction away from said cylinder so as to form a shoulder intermediate the ends of said sleeve, a port in the side of said sleeve disposed toward said cylinder as related to said shoulder so as to be normally closed by a portion of said passageway, a fluid conduit leading into the second-mentioned passageway between said sleeve valve and the second-mentioned end of said cylinder and said port being so located as to clear said shoulder upon shifting of said sleeve before said sleeve opens any part of said second mentioned passageway.

3. A bypass valve for a power lift cylinder of the type in which fluid may be introduced on either side of the piston to provide movement in either direction, said valve comprising a body portion, a passageway leading through the body portion into one end of the cylinder, a fluid supply and exhaust conduit leading into said passageway, a passageway transverse to the first-mentioned passageway and leading to the other end of said cylinder, a sleeve valve slidable in the first-mentioned passageway extending across the second-mentioned passageway so as to prevent passage of fluid from one passageway to the other, a check valve seat within the sleeve valve, a check valve element resiliently pressed against said check valve seat in a direction away from said cylinder, said sleeve valve being resiliently biased toward said cylinder, means providing for a restricted passage of fluid out of said cylinder into said first-mentioned passageway, and a fiuid supply and exhaust conduit leading into the second-mentioned passageway between said sleeve valve and the second-mentioned end of said cylinder.

4. A bypass valve for a power lift cylinder of the type in which fluid may be introduced on either side of the piston to provide movement in either direction, said valve comprising a body portion, a passageway leading through the body portion into one end of the cylinder, a passageway transverse to the first-mentioned passageway and leading to the other end of said cylinder, a sleeve valve slidable in the first-mentioned passageway extending across the second-mentioned passageway so as to prevent passage of fiuid from one passageway to the other, a check valve seat within the sleeve valve, a check valve element resiliently pressed against said check valve seat in a direction away from said cylinder, said sleeve valve being resiliently biased toward said cylinder, a second check valve seat in said transverse passageway, a check valve resiliently biased on said seat to prevent flow of fluid from the second-mentioned endof said cylinder into said first-mentloned passageway, means providing for a restricted passage of fluid out of said cylinder into said first-mentioned passageway, and a fluid conduit leading into the second mentioned passageway between the second-mentioned checkyalve and the second-mentioned end of said cylinder.

5. A bypass valve for a power lift cylinder of the type in which fluid may be introduced on either side of the piston to provide movement in either direction, said valve comprising a body portion, a passageway leading through the body portion into one end of the cylinder, a passageway transverse to the first-mentioned passageway and leading to the other end of said cylinder, a sleeve valve in the first-mentioned passageway extending across the second-mentioned passageway so as to prevent passage of fluid from one passageway to the other, a check valve seat within the sleeve, a check valve element resiliently pressed against said check valve seat, said sleeve valve being resiliently biased toward said cylinder, said firstmentioned passageway having an enlarged portion extending in a direction away from said cylinder so as to form a shoulder intermediate the ends of said sleeve, a

port in the side of said sleeve disposed toward said cylin-v References Cited in the file of this patent UNITED STATES PATENTS 2,225,518 Blasig Dec. 17, 1940' 2,252,418 Shelley Aug. 12, 1941 2,367,682 Kehle Jan. 23, 1945' 2,590,454 Pilch Mar. 25, 1952' 2,628,731 Reuter Feb. 17, 1953 2,646,025 Deardortf July 21, 1953 nun-Ar

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