US3136221A - Reciprocatory telescoping-piston hydraulic motor - Google Patents

Description

June 9, 1964 R. E. WALKER 3,

RECIPROCATORY TELESCOPING-PISTON HYDRAULIC MOTOR Filed 0012. 2'7, 1961 FIGZ INVENTOR.

ATTORNEY.

RONALD E. WALKER.

United States Patent 3,136,221 RECIPROCATORY TELESCOPING-PISTON HYDRAULIC MUTOR Ronald E. Walker, Riverside, Ontario, Canada, assignor to Phil Wood industries, Windsor, Ontario, Canada, a corporation of Canada Filed Oct. 27, 1961, Ser. No. 148,222 7 Claims. (11. 91-168) This invention relates to reciprocatory hydraulic motors and, in particular, to telescoping-piston reciprocatory hydraulic motors.

One object of this invention is to provide a reciprocatory telescoping-piston hydraulic motor equipped with cushioning means for retarding the speed of travel of the telescoping pistons by releasing hydraulic pressure fluid as they approach either or both ends of their strokes, thereby preventing the shocks which hitherto have occurred by the pistons engaging in metal-to-metal contact at the ends of their strokes.

Another object is to provide a cushioned-stroke telescoping piston reciprocatory hydraulic motor, as set forth in the preceding object wherein the retardation of the speed of travel of the pistons is brought about by providing auxiliary discharge ports opened to the exhaust circuit as the pistons near the ends of their working strokes.

Another object is to provide a cushioned-stroke telescoping-piston reciprocatory hydraulic motor, as set forth in the preceding objects wherein the auxiliary discharge ports are opened as a result of being uncovered by their associated telescoping pistons or, in the case of the outermost piston, in co-operation with one or more ports in the cylinder wall, so as to release fluid and relieve the hydraulic fluid pressure near the end of the stroke of each piston, as a result of the travel of each piston itself.

Another object is to provide a double-acting reciprocatory telescoping-piston hydraulic motor, as set forth in the preceding objects, wherein cushioning is effected on both the forward and retraction strokes.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

FIGURE 1 shows a cushioned-stroke telescoping-piston reciprocatory hydraulic motor, according to one form of the invention, with the upper half of the figure in central vertical section and the lower half mainly in side elevation with the pistons at the ends of their rearward or retraction strokes; and

FIGURE 2 is a fragmentary central vertical longitudi nal section showing the innermost telescoping piston and the next adjacent piston in their relative positions at the ends of their working or forward strokes.

Referring to the drawing in detail, FiGURE 1 shows a cushioned-stroke telescoping-piston reciprocatory hydraulic motor, generally designated 10, according to one form of the invention as consisting generally of an elongated hydraulic cylinder 12 within which is mounted a first hollow piston 14. Reciprocably mounted within the first piston 14 is a second hollow piston 16, Within which is reciprocably mounted a third hollow piston 18, within which is reciprocably mounted a fourth hollow piston 20. The fourth or innermost piston 20 also serves as a hydraulic pressure fluid supply conduit in one direction of operation and as a fluid discharge conduit in the op posite direction'of operation and is also connected to the load to be moved, such as to the dump body of a dump truck (not shown), as explained more fully below.

The hydraulic cylinder 12 has an elongated tubular cylinder barrel 22 to the rearward end of which is secured a cylinder head 24 to which in turn is secured a rearwardly-projecting bracket structure 26 carrying a bearing boss 28 in which is mounted asleeve bearing 30 containing a bearing bore 32. The bearing 30 and the bearing boss 28 are drilled to receive a lubricant fitting 34 by which the lubricant is supplied to the bearing bore 32. The latter receives a pivot shaft (not shown) mounted in any conventional manner upon a truck or other vehicle chassis (not shown) by which it can swing upward or downward while performing its work, as explained below in connec-' tion with the operation of the invention.

The cylinder barrel 22 contains a cylinder bore 36, the rearward end of which is internally threaded to receive the correspondingly-threaded reduced diameter portion The inner end of each annular closure head 40, 42, 44

or 46 is bored as at 48 and counterbored as at 50 to re-' ceive a conventional packing 52. Each counterbore 50 at its outer end is internally threaded to receive an annular packing-compressing ring or gland 54 in the form of an annular internal nut. The cylinder barrel 22 near the head 24 has axially or longitudinally-spaced ports 56 and 58 which register with correspondingly-spaced ports 60 and 62 in an elongated boss 64 welded or otherwise secured to the cylinder barrel 22 near the cylinder head 24 thereof (FIGURE 1). Bolted as at 66 to theboss 64 is a hollow service casing 68 having a rearward service port 70 registering with the rearward ports 56 and 60 and opening into a chamber 72 from which the service port 74 opens outward and is connected in any suitable way to a hydraulic fluid conduit (not shown).

Registering with the port 62 in the boss 64 is a threaded port '76 into which is threaded a tubular check valve casing 7'8 located in the chamber 72 and having a valve seat port registering with the ports 62 and 58. Mounted within the valve casing-78 is a check valve mem-' ber or ball 82 which isurged into engagement with the valve seat port 80 by a compression spring 84, the opposite or upper end of which engages the inner surface of the casing 68 as an abutment. A gasket .86 is interposed between the boss 64 and the casing 68'to prevent leakage, and is drilled or punched in alignment with the ports 60 and 62 to permit passage of fluid therethrough. The first, second and third tubular pistons 14, 16 and 18 are provided with enlarged piston heads 88, and 92 respectively which have central ports 94, 96 and 9,8 therethrough. The first, second and third piston heads 88, 90 and 92 adjacent their respective tubular piston rods 89, 91 and 93 are annularly grooved for the reception of the usual piston rings 100 for, preventing leakage. In the first, second and third tubular piston rods 89, 91 and 92 and in close proximity to the first, second and third piston heads 88, 90 and 92 are ports 102, 104 and 106. The fourth piston 20 is of slightly different construction in that its piston head 108 is composed of several pieces, the principal piece being a head member 110 having an externally-threaded reduced diameter portion 112 upon which is threaded an internally-threaded ring 114 of.

slightly greater diameter than the head member 110 so as to serve as a stop providing an annular. shoulder 115 extending above the cylindrical side surface 116.

The side surface 116 terminates at an annular shoulder 118 on an enlarged diameter portion 120, the head member 110 at this location having an internally-threaded socket 122 into which is threaded the inner end of a tubular piston rod 124. The piston rod 124 and enlarged portion are drilled to provide a port 126 containing a tubular roll pin 127 with a gap or slot along one. side thereof opening into a passageway 128 through the center of the hollow piston rod 124. Slidably mounted upon the side surface 116 of the head member 110 for axial or longitudinal travel between the annular shoulders 115 and in 118 is a sliding valve sleeve 130 which is circumferentially-grooved to receive piston rings 132 which in turn engage the inner wall of the adjacent third piston 18 for preventing leakage therebetween. The inner wall of the outer end of the third piston 18, adjacent its annular closure head 46, is provided with four circumferentiallyspaced elongated axial grooves 134 (FIGURE 2) which bypass the sliding valve sleeve 139 so as to enable flow of hydraulic fluid past the latter when the hydraulic motor is in its fully-extended position ready to start its retraction stroke.

Near its outer end, outside the annular closure head 46 of the third piston 18, the fourth piston is providedwith a port 36 leading into the passageway 12; and having an internally-threaded coupling sleeve or bushing 138 welded or otherwise secured to'the fourth piston 20 so as to provide means for coupling a flexible hose to the fourth piston 20. The extreme outer end of the fourth piston 20 is provided with a cylindrical recess 1411 within which is secure, as by welding, a bearing bushing 142 having a bearing bore 144 to which lubricant is supplied through a lubricant fitting 1415.

In the operation of the invention, let it be assumed that the service ports 74 and 136 are connected by flexible high pressure hoses to a conventional four-way hydraulicv control valve and thence to a hydraulic pump or other suitable source of hydraulic pressure fluid (not shown) which in turn is connected to a hydraulic fluid reservoir (not shown).- Let it also be assumed that the telescoping hydraulic motor 10 is in its retracted position (FIGURE 1), such as when the dump body of a dump truck is in its lowered or horizontal position and that it is desired to extend the motor 19 upon a working stroke to lift'one end of the dump body or perform other useful work by moving a particular load (not shown).

To cause the first, second, third and fourth pistons 14, 16, 18 and 20 to move outward to the right from their retracted positions shown in FIGURE 1, the control valve is so shifted'as to connect the service .port 74 to the pump or other source of hydraulic pressure fluid .and the service port 136 to the hydraulic fluid reservoir connected to the suction side of the pump.

Under these conditions, hydraulic pressure fluid flows from the service port 74 through the chamber 72, ports 78, 6t) and 56 into the end chamber of the hydraulic cylinder 12 adjacent the cylinder head 24, acting against the piston head 88 of the first piston 14 to move it outward to the right and closing the port 58 in passing. Atthe same time, pressure fluid flows from the end chamber of the hydraulic cylinder 12 of the cylinder bore 36 through the centralpiston head ports 94, 96 and 98, acting against the piston heads 9! 92 and 108 to move the second, third and fourth pistons 16, 18 and 20 outward to the right and closing the ports 102, 164 and 106 in passing. During this part of the cycle of operation, pressure of the pressure fluid within the valve chamber 72 acts against the ball check valve 82 to force it into closing engagement with its valve seat port 80 so as to temporarily prevent flow of fluid from the chamber 72 into the port 62. The ball check valve 32 remains closed by the pressure of the pressure fluid in the chamber 72, aided by the spring 84 even after the piston head 88 completely passes the cylinder wall port 58.

Meanwhile, pressure fluid flowing past the ring 114 of the fourth piston head 1118 acts against the left-hand end of the sliding valve sleeve 130 and forces it into the position shown in FIGURE 1 against the annular shoulder 118 as the fourth piston 20 moves outward to the right. At the same time, fluid displaced from the cylinder space within the cylinder bore 36 to the right of the piston head 83 and from the spaces within the first, second, third and fourth pistons 14, 16, 18 and 24) to the right of their respective piston heads .88, 9t

- 92 and 1% escapes through their respective ports 162,

' hydraulic fluid tank.

motor wherein 194, 1dr? and 126, thence through the tubular roll pin 127, the passageway 12% and the port 136 back to the hydraulic fluid reservoir. In this manner, the first, sec- 0nd, third and fourth pistons 14, 16, 1S and 21) are moved outward to their extended positions, moving the load to which the fourth piston 20 is connected at the bearing bushing 142, for example, tilting the dump body to discharge its load.

When the first, second and third pistons 14, 16 and 18 have reached their fully-extended positions in this manner, and the fourth piston 29 is nearing its fully-extended positiomthe sleeve 13% adjacent the head member 11!) thereof passes beneath the longitudinal groove 134, permitting pressure fluid to escape around the valve sleeve 13! through the port 126, the slotted tubular roll pin 127, passageway 128 and service port 136 back to the This action retards the speed of and cushions the telescoping pistons 14, 16, 18 and 20 as they near the ends of their forward or working strokes.

Tooperate the motor 11 so as to retract the telescoping pistons 14, 16, 18 and 21 the operator reverses the four-way control valve (not shown) so as to supply hydraulic pressure fluid to the service port 135 and exhaust hydraulic fluid from the service port 74. Hydraulic pressure fluid then flows via the service port 135 through the passageway 128, the slotted tubular roll pin 1 27 and port 126, shifts the valve sleeve to the left (FIGURE 2), and flows through the groove 134 and ports'126, 1535, 104 and 1192 into the annular chambers between the respective tubular piston rods, and acts against the innermost piston head member 119 and against the respective annular piston areas behind the piston heads 92, 9t and 99 to cause the pistons 20, 18, 16 and 14 to move inward to the left upon their rearward or retraction strokes, telescoping with one another as they do so. When the first piston head 38 nears the end of its retraction stroke and uncovers the port 58 in the cylinder barrel 22, the pressure fluid thenceforth passes through the ports 53, 62 and 86, lifting the ball check valve 32, and escapes through the valve casing chamber 72 and service port 74 back to the hydraulic fluid tank. This action cushions the retraction strokes of the telescoping pistons 2d, 18, 16 and 14 as they reach the limits of their return or rearward strokes by retarding their speeds. Meanwhile, the hydraulic fluid displaced from the spaces to the left of the respective piston heads 88, 91?, 92 and 1tl8'escapes through the ports 38, '96, 94 and 56, tit? and 711 into the valve casing chamber 72, and thence through the service port 74 back to the hydraulic fluid tank.

In the manner just described, the present invention provides a telescoping-piston reciprocatory hydraulic the strokes of the telescoping pistons are cushioned by theprovision for the automatic release of pressure fluid at the opposite end of their strokes, achievmg the objects set forth above at the beginning of the present specification.

What I claim is:

1. reciprocatory telescoping-piston hydraulic motor comprising a cylinder, a plurality of hollow hydraulic pistons of successively-decreasing diameters mounted within said cylinder in coaxial telescoping relationship for extension during their forward strokes and retractron during their return strokes, the outermost piston having a tubular piston rod and a piston head thereon reciprocably mounted in said cylinder and the remaining pistons having tubular piston rods and piston heads thereon reciprocably mounted in the tubular piston rods of the next larger diameter piston, means for supplyinghydraulic pressure fluid to said cylinder and pistons on one side of said piston heads and exhausting pressure fluid from the opposite side thereof, and means including cooperating elements disposed adjacent one another on said innermost piston and piston immediately adjacent thereto for releasing hydraulic pressure fluid and effecting retardation of said pistons in response to the arrival of said pistons at predetermined fluidreleasing locations near the ends of their forward strokes.

2. A reciprocatory telescoping-piston hydraulic motor, according to claim 1, wherein said hydraulic pressure fluid releasing means also includes ports in piston rods adapted to be uncovered by the adjacent piston heads and placed in communication with one of said cooperating elements at said fluid-releasing locations.

3. A reciprocatory telescoping-piston hydraulic motor, according to claim 1, wherein said hydraulic pressure fluid releasing means includes an axially-elongated passageway in one of said piston rods disposed in fluidbypassing relationship with the piston head of the next adjacent piston engageable therewith. Y

4. A reciprocatory telescoping-piston hydraulic moto according to claim 3, wherein said next adjacent piston head includes a valve member axially slidably mounted thereon.

5. A reciprocatory telescoping-piston hydraulic motor,

according to claim 4, wherein the piston head of said innermost piston has a portion fixedly attached to the innermost piston rod and wherein said axially-slidable valve member includes a hollow cylindrical piston head portion slidably mounted on said fixedly attached portion in sealing engagement with said cylinder.

6. A reciprocatory telescoping-piston hydraulic motor, according to claim 5, wherein said next adjacent piston rod has an axially-elongated fluid bypass passageway disposed in bypassing relationship with said hollow cylindrical piston head portion near one end of the stroke of said innermost piston.

7. A reciprocatory telescoping-piston hydraulic motor, according to claim 3, wherein said passageway comprises a groove in the inner wall of said next-adjacent piston rod and exceeding the axial length of said valve member.

References Cited in the file of this patent UNITED STATES PATENTS 2,364,741 Merchant Dec. 12, 1944 2,438,285 Houldsworth Mar. 23, 1948 2,517,153 Wood Aug. 1, 1950 2,783,744 Tennis Mar. 5, 1957

Claims (1)

1. A RECIPROCATORY TELESCOPING-PISTON HYDRAULIC MOTOR COMPRISING A CYLINDER, A PLURALITY OF HOLLOW HYDRAULIC PISTON OF SUCCESSIVELY-DECREASING DIAMETERS MOUNTED WITHIN SAID CYLINDER IN COAXIAL TELESCOPING RELATIONSHIP FOR EXTENSION DURING THEIR FORWARD STROKES AND RETRACTION DURING THEIR RETURN STROKES, THE OUTERMOST PISTON HAVING A TUBULAR PISTON ROD AND A PISTON HEAD THEREON RECIPROCABLY MOUNTED IN SAID CYLINDER AND THE REMAINING PISTONS HAVING TUBULAR PISTON RODS AND PISTON HEADS THEREON RECIPROCABLY MOUNTED IN THE TUBULAR PISTON RODS OF THE NEXT LARGER DIAMETER PISTON, MEANS FOR SUPPLYING HYDRAULIC PRESSURE FLUID TO SAID CYLINDER AND PISTONS ON ONE SIDE OF SAID PISTON HEADS AND EXHAUSTING PRESSURE FLUID FROM THE OPPOSITE SIDE THEREOF, AND MEANS INCLUDING COOPERATING ELEMENTS DISPOSED ADJACENT ONE ANOTHER ON SAID INNERMOST PISTON AND PISTON IMMEDIATELY ADJACENT THERETO FOR RELEASING HYDRAULIC PRESSURE FLUID AND EFFECTING RETARDATION OF SAID PISTONS IN RESPONSE TO THE ARRIVAL OF SAID PISTONS AT PREDETERMINED FLUIDRELEASING LOCATIONS NEAR THE ENDS OF THEIR FORWARD STROKES.

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