US3185040A

US3185040A - Hydraulic reciprocating system

Info

Publication number: US3185040A
Application number: US273090A
Authority: US
Inventors: Ligon D Elmon
Original assignee: American Brake Shoe Co
Current assignee: American Brake Shoe Co
Priority date: 1963-04-15
Filing date: 1963-04-15
Publication date: 1965-05-25
Anticipated expiration: 1982-05-25

Description

May 25, 1965 Filed April l5, 1963 D. E. LIGON HYDRAULIC RECIPROCATING SYSTEM 2 Sheets-Sheet 1 a; T-'5:5 256 7.1- I@ INVENTOR May 25, 1965 D. E. LlGoN HYDRAULIC RECIPROCATING SYSTEM 2 Sheets-Sheet 2 Filed April 15, 1963 1 Cm ..l I

frage/ffm United States Patent O 3,185,040 HYDRAULIC RECIPROCATING SYSTEM D. Elmon Ligon, Denver, Colo., assigner to American Brake Shoe Company, New York, NX., a corporation of Delaware Filed Apr. 15, 1963, Ser. No. 273,090 Ciaims. (Cl. 91-277) This invention relates to hydraulic self-reciprocating systems and more particularly to a system which is operable to reciprocate a hydraulic piston automatically and Without the customary manual or electrical control at the end of each stroke.

It has been an objective of this invention to provide a hydraulic linearly reciprocating motor or pump having hydraulic control means built in-to the reciprocated member such that when the reciprocated member reaches the end of a stroke the system will automatically cause the member to move linearly in the opposite direction, without the assistance of conventional manual or electrically controlled valves. To this end this invention incorporates uid passageways into the reciprocated piston operable to selectively actuate a pilot valve at the end of each stroke. The pilot valve in turn controls a main ow control valve which causes reversal of .the direction of the fluid flow to and from the main piston. With this arrangement the piston continues to automatically reciprocate so long as pressure is maintained to the system.

Another objective of this invention has been to provide an inexpensive hydraulic reciprocating system having a minimum number of parts subject to wear or breakdown. Continuous operating time for a reciprocating piston in accordance with this invention may be measured in terms of thousands of running hours even at relatively high speeds under adverse conditions. For example, this system has found one application as a rugged, heavy duty motor for compacting wet concrete. Advantageous utilization of the invention for this purpose results from the fact that there are no mechanical linkages or components subject to wear, clogging or breakage.

Another objective of this invention has been of provide a hydraulic reciprocating system displaying no dead spots in operation. A dead spot is a piston location at which maximum power cannot be supplied to 4the reciprocating piston. In many systems .this phenomenon occurs at the beginning of a stroke where back pressure on the piston may cause the control valve to lock in some intermediate position at which there is no fluid ow or very little flow to either side of the main piston. To eliminate dead spots this invention incorporates a pilot valve into the system operable to control movement of the main control valve.

Yet another objective of this invention has been to provide an adjustable stroke reciprocating motor which has no manual or electrically controlled valve to determine the length of the piston stroke. Thus, this motor is particularly adapted for use in heavy duty installations where breakdown is intolerable or where the motor is subject to extended running time.

These and other objectives and advantages of this invention will be more readily apparent from a description of the drawings in which:

FIGURE l is a diagrammatic illustration of one embodiment of the motor and control system, partially in cross section, showing the control valves in the position for moving the main piston from right to left,

FIGURE 2 is a diagrammatic illustration similar to FIGURE l but showing the control valves in the position for moving the main piston from left to right,

FIGURE 3 is a diagrammatic illustration of a second embodiment of the invention,

ICC

FIGURE 4 is a cross sectional view of another embodiment of the motor in which the piston stroke is adjustable.

Referring to FIGURES 1 and 2, it will be seen that the reciprocating system consists essentially of a reciprocating motor 1t), a pilot valve 11 and a main control valve 12. The pilot valve 11 and main control valve 12 are used in the system to control flow of hydraulic uid under pressure to opposite ends of the piston 13 of the motor 10.

The reciprocating member or motor piston 13 is slidingly and sealingly mounted within a housing or cylinder 14 and has a piston rod 15 which extends through a bearing block 16 at one end of the cylinder 14. The opposite end of the cylinder 1d is enclosed by an end plate 17. Fluid is supplied to the opposite sides of the piston 13 through

pressure ports

20, 21 in the bearing block 16 and end plate 17 respectively.

A port block 22 is mounted on the end of the bearing block 16 and has a central bore 23 co-axial with the bore 24 in the bearing block. An end cap 26 is mounted over the forward end of the port block 22 and also has a central aperture 27 co-axial with and of the same size as the

bores

23, 24 in the port block and bearing block. The

end plates

17, 26, the bearing block 16, and port lock 22 have a plurality of aligned apertures therein which receive bolts 36 to hold the components of the reciprocating motor in assembled relationship.

The port block 22 has four

pressure ports

31, 32, 33 and 34 extending radially from the central bore 23. Two of the

pressure ports

32, 33 are located in the same radial plane on opposite sides of the port block. In the same manner but spaced axially from the

pressure ports

32, 33, the

pressure ports

31, 34 are located on opposite sides of the port block in the same radial plane. The

ports

31, 32 are both connected to a pressure source such as pump 3S by conduits 39, 4) and 41.

Ports

33, 34 are connected to ports 43, 44 of pilot valve 11 by means of conduits 4S, e6 respectively such that pressures from

ports

33, 34 is operable to control movement of the piston 4S of pilot valve 11.

The port block also has four

drain ports

50, 51, 52 and 53 located adjacent the

pressure ports

31, 32, 33 and 34 respectively with two of the

drain ports

50, 53 located in the same radial plane but on opposite sides of the port block and the other two

drain ports

51, 52 similarly located on opposite sides of the port block and in the same radial plane. Two of the

drain ports

50, 51 are connected to reservoir or tank 55 by

conduits

56, 57 respectively while the drain port 52 is connected to conduit 46 by a conduit 53 and port 53 is connected to conduit 45 by a conduit 59.

In the forward position of the motorpiston 13, the

pressure ports

32, 33 and the

drain ports

51, 52 are .adapted to be interconnected to form a pair of fluid passages. To this end, the piston rod 15 has a pair of annular grooves 60, 61 formed in its peripheral surface which in the forward position of the motor, becomes aligned with the

pressure ports

32, 33 and the

drain ports

51, 52. In the rearward position of the motor piston 13, the grooves are aligned with and interconnect the

pressure ports

31, 34 and the drain ports S0, 53.

The pilot valve 11 is a four-way hydraulic valve and consists of a cylinder 62 within which the piston 48 is slidable to either of two positions in an axial bore 63. The central bore 63 is open at one end to piston port 43 and at the opposite end to piston port 44. Equally spaced along the central bore 63 are iive

annular grooves

64, 65, 66, 67 and 68 which serve as fluid passageways. The central groove 6e is connected to a pressure intake port (shown in dotted lines) 74B which is connected to pump er 38 by

conduits

71, 72. The two adjacent passageways or

annular grooves

65, 67 are connected to pressure ports 73, 74 respectively. Ports 73, 74 are in turn connected to

ports

75, 76 of the main control valve 12 by conduits 7'7 and 78 respectively in such a manner that pressure from these ports is operable to control the main control valve 12. The outermost annular grooves 64, 68 are connected to the reservoir tank`55 by

passageways

81, 82 and drain port 80 in the pilot valve cylinder 62.

The piston 48 of pilot valve 11 has a pair of axially spaced grooves 85, 86 located therein and adapted in one position to connect passageways 67, 68 and

passageways

65, 66 and in the other position to connect

passageways

66, 67 and

passageways

64, 65. The purpose of this interconnection of passageways will be more fully explained hereinafter in connection with the operation of the system.

Main control valve 12 is a four-way valve structurally similar to pilot valve 11. It` consists of a cylinder 90 within which apiston 91 is slidable in an axial bore 92 to either of two positions. The central bore 92 is connected at one end to port 75 and at the opposite end to port 76. Equally spaced along the central bore 92 are ve annular grooves or

fluid passageways

93, 94, 95, 96 and 97. The central groove 95 is connected to a pressure intake port (shown in dotted lines) 98 which is connected by conduits 99 and 72 to the pump 38. The two adjacent passageways or annular grooves 94, 96 are connected to

pressure ports

100, 101 respectively.

Ports

100, 101 are in turn connected to

ports

20, 21 of the motor 10 by

conduits

102 and 103 respectively so that pressure from these ports is operable to control reciprocation of piston 13. The outermost

annular grooves

93, 97 are connected to drain port 104 by means of passageway 105 in the main control valve cylinder 90.

The piston 91 of main control valve 12 has a pair of axially spaced

grooves

106, 107 located therein and adapted in one position to connect passageways 96, 97 and passageways 94 and 95 and in the other position to connect passageways 95 and 96 and passageways 93v and 94. The purpose of this interconnection of passageways will be more fully explained hereinafter in connection with the operation of the system.

Referring to FIGURE 1, the pilot valve 11 and the main control valve 12 are shown in the position for moving the piston 13 from right to left, or forwardly. With the piston moving in this direction fluid pressure is supplied from the .pump 38 via

conduit

72, 71 to the pilot valve 11 and through the pilot valve via passageway 66, groove 86, passageway 65 and conduit 77 to the port 75 of the main control valve 12. The pressure in port 75 causes the piston 91 of the main control valve to move to the left and to remain in that position so long as the motor piston 13 is moving forward. Fluid pressure is supplied to the port 21 of the motor 10 from the pump 38 Via conduits 72 and 99 to the pressure inlet port 98 and via passageway 95, groove 107, passageway 94 vthrough conduit 103 to the port 21. Fluid is exhausted at this time from the forward side of piston 13 via port 20, conduit 102, passageway 96, groove 106 and passageways 97, 105 to drain port 104 from whence it is conducted to the reservoir or tank 55.

When the piston 13 arrives at its forward limit of movement, the grooves 60, 61 in the piston rod 15 become aligned with the

ports

32V, 33 and 51, 52 respectively. Upon alignment of the piston rod groove 60 with the

pressure ports

32, 33 fluid pressure is supplied to the left end of pilot valve piston 48 so as to cause it to move to the right. This movement results from fluid pressure being supplied from pump 38 via conduits 39,141, groove 60 and conduit 45 to the valve piston port 43. Sirnultaneously uid is exhausted from the right side of the piston 48 via

conduits

46, 58, drain port 52, groove 61, drain ports 51 and conduitV 57 to the tank 55. With the pilot valve piston 48 in the position illustrated in FIGURE 2,

uid pressure is supplied tothe left end of the control valve piston 91 so as to cause the piston to move toward the right. This pressure is supplied from pump 38 by

conduits

72, 71, passageway 66, groove and conduit 78 to the main control valve piston port 76. At this time uid is exhausted from the right side of piston 91 via conduit 77, passageway 65, groove 86,

passageways

64 and 82 to the tank 55. Thus the location of the'motor piston 13 at itsforward limit of movement causes repositioning of the

pistons

48 and 91 of the pilot valve 11 and main control valve 12 so as to start the motor moving in the rearward direction.

With the main control valve 12'located in the FIG- URE 2 position, uid pressure is supplied to the forward side of motor piston 13 and exhausted from the rear side. The pressure to the forward side of the piston 13 is supplied from the pump 38 via conduits 72 and 99, passageway 95, groove 106, passageway 96, and conduit 102 to the motor port 20. Simultaneously fluid is drained from the rear side of the piston via conduit 103, passageway 94, groove 107, passageways 93, 105 to the drain port 104 and hence to storage tank 55. At this time the piston 13 moves rapidly to the right or rearwardly because they eifective area against which the pressure reacts is smaller than the area 111 against which the uid acts to move the piston in the forward direction. Otherwise expressed, the forward fluid chamber 112 is of much less volume than the chamber 113 and therefore requires less iiuid flow to cause the same amount of linear movementof the piston in the rearward direction than in the forward direction. Thus the piston moves rapidly to the right and slowly in the forward direction to the left. However, in moving to the left at the slower rate of speed, the piston has a much greater mechanical advantage as a result of the greater piston area, and thus is able to apply a much greater force on a load than that which it is capable of applying in a rearward direction. In those applications in which it is desirable to move the piston at the same rate of speed in both the forward and rearward directions, the piston rod 15 maybe extended rearwardly from the rear surface 111 of the piston through the end plate 17, so that the etfective area against which the fluid pressure reacts in moving the piston in both the forward and rearward direction will be equal.

When the piston 13 has moved all the way to the right or to the rearward limit of its movement, the piston rod grooves 60, 61 :become aligned with the

ports

50, 53 and the

ports

31, 34 respectively. The pilot valve 11 and the main control valve 12 are then moved into their first position as illustrated in FIGURE 1 so as to cause movement of the piston from right to left or in the forward direction. At this time pressure is supplied from the pump 38 via

conduits

39 and 40, port 31, groove 61, port 34, and conduit 46, to `the right end of piston 48. Simultaneously fluid is exhausted from the left end of piston 48 so as to permit the piston to move to the leftv or into its first position. The fluid is drained through portl 43,

conduits

45, 59, drain port 53, groove 60, drain port 50' and conduit 56 to the tank 55.v

When the pilot valve is actuated or moved into its rst position it causes the main control valve to also be moved into the rst position. This occurs as a result of fluid pressure being supplied from the pump 38 via conduits 72,V 71, passageway 66, groove S6, passageway 65 and conduit 77 to the main control valve piston port 75.

Simultaneously uid is exhaustedl from the control valve port 76 via conduit 78, passageway 67, groove 85, passage- Ways 68, 81 to the drain port 80 and thus to the tank 55.

With both the pilot valve 11 and the main control valve 12 located in their first positions, the motor piston 13 again moves from right to left or rearwardly. Fluid at this time is supplied to the rear of piston 13 from pump 38 via conduits 72, 99, passageway 95, groove 107, passageway 94 and conduit 103. Simultaneously fluid is exhausted from the forward side of piston 13 via conduit 102, passageway 96, groove 106 and passageways 97, 105 to the drain port 104.

As should now be obvious, the hydraulic reciprocating system of FIGURES l and 2 is operable to reciprocate the motor piston 13 continuously or automatically without the assistance of any manual or electronic control valves, so long as pressure is supplied from the motor 38 to the various pressure inlet ports.

Referring to FIGURE 3, there is shown a second embodiment of the invention. In this embodiment, similar numerals followed 'by the suiiix a are used to designate parts which are identical to those of FIGURE 1.

The principal difference between the embodiment of FIGURE 3 and that illustrated in FIGURE 1 resides in the fact that the piston rod 120 extends axially from both ends of the piston 121 through port blocks 122 and 123 mounted on both ends of the cylinder 124. The port blocks 122, 123 each have a pair of radially aligned

pressure ports

127, 128 and a pair of radially aligned

drain ports

129, 130.

At each end or on both sides of the piston 121, the piston rod 120 has a pair of spaced

annular grooves

132, 133. The

grooves

132, 133 are axially spaced apart the same distance as that between the pressure ports 127 and the drain ports 129.

The

pressure ports

127 and 128 and the

drain ports

129, 130 are connected to the pump 38a, the pilot valve 11a and the main control valve 12a in the identical manner as disclosed relative to the FIGURE 1 modification. Thus, the piston 121 continues to reciprocate and change its direction of linear motion at each end of its stroke so long as pressure is supplied from the pump to the motor. At each end of the stroke, the pressure ports 127 and 12S are interconnected by the annular groove 132 and the

drain ports

129 and 130 are interconnected by the annular groove 133. The primary advantage of the FIGURE 3 modiication over that of FIGURE 1 resides in the fact that the piston and piston rod of this modification are balanced so that there is no tendency for the piston 121 to skew relative to the cylinder 124. Thus wear between these parts is minimized, since a port block is located at each end of the cylinder 124 and each block acts as a guide to maintain alignment between the cylinder and piston.

Referring to FIGURE 4, there is shown another modification of the system in which the stroke of the piston is adjustable. In this modification elements which are similar to the modiiication of FIGURE l are designated by identical numbers followed by the suflix b.

While the pilot valve and main control valve have not been illustrated in this modification, Vit should be understood that these parts are identical to the FIGURE l modiication and are connected in the same manner.

In this modification, the piston rod 140 is made from two relatively

adjustable sections

141 and 142. Each section has a pair of peripheral

annular grooves

143, 144 and 145, 146 respectively which are spaced apart the same distance as that between the drain ports and the pressure ports. By adjusting the relative positions of the

sections

141, 142, the distance between the two pairs of

grooves

143, 144 and 145, 146 may be altered.

For purposes of adjusting the distance between the pairs of grooves, the piston rod section 141 has a threaded end portion 150 which is of less diameter than that of the piston rod 141. The other piston rod section 142 is threaded onto the threaded portion 150 of the member 141 so as to be adjustable thereon. A lock nut 151 is also threaded on the end of the threaded section 150 to lock the member 142 in any adjusted position.

At one end of the piston stroke, the grooves 143 and 144 interconnect the drain ports 50b and 53b and the pressure ports 31b and 341: respectively. At the opposite end of the stroke, the groove 145 interconnects theV pressure ports 32b and 33b and the groove 146 interconnects the drain ports 51b and 52b. By adjusting the pair of grooves 145, 146 to a position closer to the 6 grooves 143, 144, the stroke of the piston may be lengthened and by moving the pair of grooves further apart, the stroke may be appreciably shortened. Thus, the adjustment between the grooves provides an infinite number of piston stroke adjustments.

Having described my invention, I claim:

l. A variable stroke hydraulic reciprocating system comprising,

a hydraulic cylinder,

slidable means including a piston and piston rod mounted within said cylinder,

a plurality of ports associated with said cylinder,

valve means operable to control uid flow to opposite ends of said piston,

said slidable means having a plurality of fluid passageways operable to selectively connect said ports to said valve means and thereby control said valve means, and

means for varying the spacing between said ports and said passageways to alter the length of the stroke of said piston Within said cylinder.

2. A hydraulic reciprocating system comprising,

a hydraulic cylinder,

a piston having a piston rod extending through one end w-all of said cylinder,

a port block attached to one end wall of said cylinder,

said piston rod extending into said port block,

valve means operable to control fluid flow to opposite ends of said piston,

said piston rod having a plurality of uid passageways operable to selectively connect ports in said port block to said valve means and thereby control said valve means, and

means for adjusting the distance between said ports and said iuid passageways to vary the stroke of said piston within said cylinder.

3. A fluid energy translating device comprising,

a hydraulic cylinder,

a piston mounted within said cylinder and having a piston rod extending through one end wall of said cylinder,

a port block attached to one end wall yof said cylinder,

said piston rod extending into said port block,

said port block having a plurality of connectable ports therein,

said piston rod having a plurality of fluid passageways operable to selectively interconnect ports in said port block, and

means for adjusting the distance between said ports and said fluid passageways to vary the stroke of said piston Within said cylinder.

4. A iiuid energy translating device comprising,

a hydraulic cylinder,

a port block attached to one end Wall of said cylinder,

.said piston rod extending into said port block,

said port block having a plurality of connectable ports therein,

said piston rod having a plurality of axially spaced iiuid passageways operable to selectively interconnect ports 1n said port block, and

means for adjusting the distance between said fluid passageways to vary the stroke of said piston within said cylinder.

5. A uid energy translating device comprising,

a hydraulic cylinder,

a piston mounted within said cylinder and having .a piston rod extending through one end wall of said cylinder,

a port block attached to one end wall of said cylinder,

said piston rod extending into said port block and having two relatively axially adjustable sections located within said port block,

said port block having a plurality of connectable ports therein,

each of saidpiston rod sections having a plurality of fluid passageways operable to selectively interconnect ports in said port block, and

threaded means betweeny said sections for varying the relative positions of said sections to alter the spacing between said fiuid passageways and thereby vary the stroke of said piston Within said cylinder.

References Cited by the Examiner UNITED STATES PATENTS 720,263 2/03 Lepley 91-2'77 Ernst 91-308 Morgan 91-277 Holm 9 1-461 Schemmel 91-297 Ellis `91-314 Paris 91-317 Coberly 91-308- FOREIGN PATENTS Great Britain. Switzerland.

FRED E. ENGELTHALER, Primary Examiner.

7/ 10 Jenner 91-308 15 SAMUEL LEVINE, Examiner.

Claims

1. A VARIABLE STROKE HYDRAULIC RECIPROCATING SYSTEM COMPRISING, A HYDRAULIC CYLINDER, SLIDABLE MEANS INCLUDING A PISTON AND PISTON ROD MOUNTED WITHIN SAID CYLINDER, A PLURALITY OF PORTS ASSOCIATED WITH SAID CYLINDER, VALVE MEANS OPERABLE TO CONTROL FLUID FLOW TO OPPOSITE ENDS OF SAID PISTON, SAID SLIDABLE MEANS HAVING A PLURALITY OF FLUID PASSAGEWAYS OPERABLE TO SELECTIVELY CONNECTED SAID PORTS TO SAID VALVE MEANS AND THEREBY CONTROL SAID VALVE MEANS, AND MEANS FOR VARYING THE SPACING BETWEEN SAID PORTS AND SAID PASSAGEWAYS TO ALTER THE LENGTH OF THE STROKE OF SAID PISTON WITHIN SAID CYLINDER.