US3434392A - Hydraulic system for operating a cylinder - Google Patents

Description

March 25, 1969 H. s. LANDERS HYDRAULIC SYSTEM FOR OPERATING A CYLINDER Sheet of 3 Filed April 24. 1967 72 rs, \W x INVENTOR ATTORNEY HARVEY 3. LANDERS March 25, 1969 H. s. LANDERS 3,434,392

HYDRAULIC SYSTEM FOR OPERATING A CYLINDER Filed April 24, 1967 Sheet g of 3 l W2 14 I3 HARVEY S. LANDERS INVENTOR.

ATTORNEY March 25, 1969 H. s. LANDERS 3,434,392

HYDRAULIC SYSTEM FOR OPERATING A CYLINDER Filed April 24, 1967 Sheet 3 of 5 HARVEY S; LANOES INVENTOR.

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ATTORNEY 3,434,392 HYDRAULIC SYSTEM FOR OPERATING A CYLINDER Harvey S. Landers, 207 E. Broadway, Fort Worth, Tex. 76118 Filed Apr. 24, 1967, Ser. No. 632,969 Int. Cl. F15b 11/08, 13/04 U.S. Cl. 91414 3 Claims ABSTRACT OF THE DISCLOSURE A hydraulic system for operating a cylinder and piston and including a high pressure low volume pump, and a high volume low pressure pump, both of which pumps operate simultaneously. A control block in the system has three valves therein whereby the piston in the cylinder is moved rapidly at the beginning of its stroke and whereby increased pressure is applied near the end of the stroke.

This invention relates to hydraulic systems and has reference to a valve arrangement whereby a piston in a cylinder may be moved rapidly at the beginning of its stroke, yet increases its force near the end of its stroke.

The invention may be used in the compressing of mineral blocks such as those placed in feed lots and pastures for cattle. However, the invention is capable of other uses, for example, compressing and extruding feed in pellet form.

An object of the invention is to eliminate shock or water hammer at the ends of the strokes of the piston in a hydraulically operated cylinder and thereby reduce fatigue in the hydraulic system.

Another object of the invention is to control the direction, velocity and delivered force of a piston in a hydraulically operated cylinder by changing the direction of return flow in the system.

A further object is to apply constant pressures in the direction of both sides of the piston at all times, thereby lending to the elimination of shock as refer-red to in the first herein stated object.

A further object is to include an auxiliary cylinder in a hydraulic system such as referred to and wherein the return fluid from the auxiliary cylinder provides pilot fluid for operating certain valves in the control block.

These and other objects of the invention will become apparent from the following description and the accompanying drawings, wherein:

FIGURE 1 is a broken elevational and sectional view of the control block and solenoid operated valves for regulating flow to the primary or working cylinder for controlling the action of the piston therein.

FIGURE 2 is a sectional view taken on line 22 of FIGURE 1.

FIGURE 3 is a sectional view taken approximately on line 33 of FIGURE 1.

FIGURE 4 is a diagram of a hydraulic system according to the invention.

FIGURE 5 is a schematic view of the primary cylinnited States Patent 0 ice de-r, control block and connecting lines, and showing the piston in its retracted position.

FIGURE 6 is a view similar to FIGURE 5, but showing the piston of the cylinder in an initially actuated position.

FIGURE 7 is a view similar to FIGURE 6 but show ing the piston in a further extended position.

FIGURE 8 is similar to FIGURES 5-7 but shows the return movement of the piston.

In the hydraulic system shown, FIGURE 4, there is a main working cylinder 10, a piston 11 therein, an extending piston rod 12 and a ram 13 on the extending end of the rod. The ram 13 is slidable in an open end pressure chamber 14 having a supply hopper 15 communicating therewith. Outwardly of the open end of the pressure chamber 14 there is a delivery chute 16, and between the chamber and the chute there is a transverse slidable gate 17. The components thus far referred to are conventional and are not, therefore, herein described in detail.

A high pressure low volume pump 18 is in constant communication with the piston end of the cylinder 10 by means of a line 19, and a low pressure high volume pump 20 is in constant communication with the rod end of the cylinder by means of another line 21. Between the cylinder 10 and pumps 18 and 20 there is a valve block 22 having parallel passageways 23 and 24 which are connected, respectively, with the hydraulic lines 19 and 21. A transverse passageway 25 extends through the block 22 and communicates with both of the passageways 23 and 24. The ends of the transverse passageway 25 are connected with return lines 26 and 27 extending to a reservoir 28 which, in turn, is connected with the pumps 18 and 20 and a third pump 29 by means of branched supply lines 30.

The referred to auxiliary cylinder is shown only in FIGURE 4 and is identified by reference numeral 31. This cylinder 31 is for operating the gate 17 and includes a piston 32 and extending piston rod 33 to which the gate 17 is attached. The third pump 29 has a line 34 extending to a solenoid operated plunger type fourway valve 35 which is connected to the piston and rod ends of the auxiliary cylinder 31 by lines 36 and 37. The last referred to lines 36 and 37 have bypasses 38 and 39 communicating with the second described passageway 24. In the bypass lines there are spring loaded pressure relief valves 40 and 41 for relieving excess pressure in the lines 36 and 37. As shown in FIGURE 3, the bypass lines 38 and 39 are joined inwardly of their relief valves 40 and 41 where they are connected with a common passageway 42 to the second described passageway 24. As will become apparent, fluid reaching the last referred to passageway 24 is returned to the reservoir 28.

The fourway solenoid operated valve 35 includes a coil 43 mounted on the valve block 22, an armature (not shown), a piston 44 slidably mounted in a cylinder 45 in the block, and a stem 46 connecting the armature with the piston. The piston 44 is normally extended into the block 22 by reason of a compression spring 47 around the stem 46 and between the piston and the coil 43. As shown in FIGURE 3, fluid from the pump 29 and line 34 enters a passageway 48, moves through an arcuate passage 49 in the piston 44 and into the line 36 and thereby extends the piston 32 in the auxiliary cylinder 31. At the same time, return fluid through line 37 passes through an arcuate passage 50 in the piston 44, through the connected passageway 42 and to the second described passageway 24 in the block 22. When the coil 43 of the valve 35 is energized the valve piston 44 is moved to a position whereby other arcuate passages 51 and 52 (see FIGURE 1) register the passageway 48 and the return from line 36 with passageway 42, thus reversing the flow last described.

Within the valve block 22, and connected with the line 34 from the pump 29, there is a pressure passageway 53 for supplying pilot fluid to spool type selector valves 54, 55 and 56 which are best illustrated in FIGURE 2. The spool valves 54, 55 and 56 are, respectively, operated by first, second and third solenoid valves 57, 58 and 59. Each solenoid valve 57-59 includes a coil 60, a piston 61 slidably mounted in a cylinder 62 in the block 22, an armature 63 and a stem 64 connecting the armature and the piston. A conformingly shaped cylindrical housing 65 mounts each coil 60 on the block 22 and a spring 66 therein locates and cushions each piston in a normally extended position. The end of each spring 66 opposite its piston 61 rests on a ring support 67 in the housing 65.

The first spool valve 54 includes a piston 68 slidably mounted in a sleeve 69 transversely disposed in the valve block 22 and which piston normally rests against a passage block 70 on the valve block 22 and has a pressure passageway 71 which communicates, at one end, with the interior of the sleeve 69. Similarly, there is a relief passageway block 72 on the valve block 22 at the other end of the sleeve 69, and which passageway block has a passageway 73 for relieving pressure at that end of the piston 68. There is a groove 74 around the piston 68, which groove is located toward pressure passageway block 70 so that a surface portion of the piston normally closes the transverse passageway 25 through the valve block 22. The relief end of the piston 68 is axially recessed to receive one end of a compression spring 75, the other end of which bears against the relief passageway block 72. The pressure and relief passageway blocks 70 and 72 may be secured to the valve block 22 by suitable means such as gaskets and screws, not shown.

Referring now particularly to FIGURE 3, there are branch lines 76 in the valve block 22 connecting the pressure passageway 53 with arcuate passages 77 in the pistons 61, which passages are connected with the spool valve pressure passageways 73 when the pistons 61 of the solenoid valves are actuated. At the same time, the relief lines 71 of the spool valves 54-56 are in communication with arcuate passages 78 in the pistons 61 which, in turn, communicate with a relief line 79 in the block 22 and which relief line is connected with the transverse passage 25. When the pistons 61 of the solenoid valves 57-59 are raised (that is, when the coils 60 are not energized) arcuate passages 80 in the pistons connect the pressure branch lines 76 with the relief passageways 73.

At the same time, other arcuate passages 81 in the pistons 61 communicate the passageways 71 extending to the spool valves 54-56 with the relief line 79 in the valve block 22.

Except for the location of their circumferential grooves 82, the second and third spool valves 55 and 56 are like the first spool valve 54; accordingly, all like parts have the same reference numerals. The grooves 82 are located to normally permit passage of fluid in those portions of the transverse passageway 25 on either side thereof.

On the ends of the valve block 22 there are smaller blocks 83 and 84 having small passageways 85 and 86 which connect the transverse passageway 25 with other passageways 87 and 88 in the valve block 22 and extend to the parallel passageways 24 and 23. Relief valves 89 and 90 are provided at the outer ends of the small passageways 85 and 86 and are arranged to permit flow from the parallel passageways 24 and 23 when pressure is excessive. As shown in FIGURES 1 and 3, the extending length of the relief line 79 is in the second mentioned small block 84 where it connects with the transverse passageway 25.

Referring now to FIGURES -8, all three pumps 18, 20 and 29 operate at the same time and during all phases of operations. Thus, hydraulic fluid enters the parallel passageways 23 and 24 and either reaches the ends of the working cylinder 10 or is diverted by the selected positions of the spool valves 54-56. As described in the foregoing, the spool valves 54-56 are operated by the solenoid valves 57-59. The latter (57-59) are operated by electrical circuits and selector switches, not shown.

In FIGURE 5 the piston 11 is retracted in the cylinder 10 and the high pressure low volume fluid is directed toward the rod end of the cylinder through line 21 and some pressure is applied to the piston end through line 19. The direction of flow and pressure shown by the arrows is because the first spool valve 54 blocks the transverse passageway 25 outwardly of the second parallel passageway 24. At this time the second and third spool valves 55 and 56 are open and fluid not utilized flows through the unblocked portion of the transverse passageway 25, through the return line 26 and into the reservoir 28.

In FIGURE 6 the first and third spool valves 54 and 56 are closed, thus directing fiuid from the high volume low pressure pump 18 to the line 19 connected with the piston end of the cylinder 10. At the same time fluid from the low pressure high volume pump 20' is also directed to the piston end of the cylinder 10 through the center portion of the transverse passageway 25 and the line 19. This action causes the piston 11 to move rapidly at the beginning of its stroke. At the same time, return fluid from the rod end of the cylinder 10 flows through line 21 to the transverse passageway 25. Near the end of the stroke the first valve 54 is opened and the second and third valves are closed. FIGURE 7, thereby confining and directing all of the fluid from the first pump 18 to the piston end of cylinder 10 with the result that the piston 11 moves slower but with greater force. Before the end of a full stroke of the piston 11, the first and second spool valves 54 and 55 are closed and the third valve 56 is opened with the result that the piston changes its direction. At this time fluid in the piston end of the cylinder 10 is returned through line 19, passageway 23, the open valve 56 in that portion of the transverse passageway 25 and through the return line 26.

What is claimed is:

1. In combination with a cylinder having a piston therein and an extending piston rod: first and second passage means connecting fluid pressure means with the piston and rod ends of said cylinder, transverse passage means connecting said first and second passage means and extending outwardly of each side thereof, and first, second and third valves in said transverse passage means, the second said valve being located between said first and second passage means and the first and third said valves being located outwardly and on each side of said first and second passage means and including a valve block through which said first and second passage means and said transverse passage means extend, and wherein said valves are spool type valves slidably mounted in said block.

2. The combination defined in claim 1, and including solenoid valve means operating said spool type valves by means of pilot fluid.

3. The combination defined in claim 1, and including an auxiliary double acting cylinder, and means supplying said pilot fluid from the return from each end of said double acting cylinder.

References Cited UNITED STATES PATENTS 2,570,622 10/1951 Willis 91-437 3,129,720 4/1964 Allen et al. 91436 PAUL E. MASLOUSKY, Primary Examiner.

US. Cl. X.R.

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