JP2009013908A - Piston pump or motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce noise due to trapping at a top dead center and a bottom dead center of a piston pump or a motor. <P>SOLUTION: Open holes 41, 42 are provided at the top dead center and the bottom dead center respectively, and are connected to a high pressure side port via a check valve 45. The open holes are connected by communication path 43 and are connected to the high pressure side port via a check valve. An outlet 46 of the check valve is connected to a shuttle valve 50, a high pressure port side out of the two ports is selected and closing pressure generated at the top dead center and the bottom dead center is released to the high pressure port side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piston pump or a motor, and more particularly to a piston pump or a motor that can be used for both the pump and the motor and has reduced noise in the closing stroke.

  Conventionally, for example, a plurality of piston holes radiated in a cylinder made rotatable with respect to a rotation support shaft, and a high-pressure or low-pressure port provided on the rotation support shaft side in communication with the piston hole are selectively used. A piston chamber is formed by the opening hole that communicates with the piston that is movable in the radial axis direction in the piston hole, and the shoe that is swingably coupled to the piston chamber side opposite to the piston as the cylinder rotates. A radial piston pump or motor that performs a pump or motor action by expanding and contracting a piston chamber by sliding a partial cylindrical surface provided at the tip of the cam ring on the inner peripheral surface of the cam ring is known. It is known that the noise of such a radial piston pump or motor increases when the pressure oil in the cylinder chamber is discharged to the low pressure side at once. For this measure, in Patent Document 1, a pressure reducing accumulator is provided at the top dead center and a pressure accumulator is provided at the bottom dead center side to prevent a sudden decrease in pressure in the cylinder chamber and to reduce noise.

Further, in Patent Document 2, in a slanted shaft type variable displacement motor which is a kind of an axial piston pump or a motor, a communication hole opened at a dead point (top dead center and bottom dead center) between a high pressure side and a low pressure side valve port of a valve plate. And a pressure adjustment valve connected to the tank is provided to prevent the confining pressure and reduce noise.
JP 2002-364525 A JP-A-11-280636

  However, in Patent Document 1, although the method of use as a pump is effective, it is not suitable for a method of use in which the rotation direction of a motor is different and the high pressure side changes. Moreover, since the pressure accumulator is provided, there is a problem that the size increases and the cost increases.

  Further, in Patent Document 2, there is a problem that if the set pressure of the pressure adjusting valve is set to the maximum load pressure, there is no effect in closing at a low pressure, and no noise countermeasure is taken. On the other hand, if the set pressure of the pressure adjustment valve is lowered, high pressure oil will flow to the low pressure side through the communication hole and pressure adjustment valve when the cylinder hole extends over the notch (relief groove) and communication hole on the high pressure side. In the case of a hydraulic motor, there is a problem that a high pressure is generated due to the supply pressure and the inertial force from the load, and cannot stop at a low speed. In order to solve such a problem, the pressure of the pressure adjusting valve must be adjusted each time depending on the use pressure and the generated pressure. In addition, when the confining pressure escapes from the pressure adjusting valve into the case, surge pressure is generated in the case, and the oil seal may be damaged. In addition, when piping separately, there was a problem such as an increase in cost.

  The present invention has been made in view of the above-described conventional problems, and is designed to reduce the noise by preventing the cylinder from being closed in the piston chamber of the top dead center and the bottom dead center, and also when using the motor. An object of the present invention is to provide a piston pump or a motor that has a simple structure and is surely operated with less problems of stopping at a low speed, less influence of pressure conditions, and less occurrence of surge pressure.

  In the present invention, a piston chamber is formed by pistons that can enter and exit from a plurality of piston holes provided at equal intervals in a rotating cylinder, and the pistons are sequentially reciprocated so that each rotation of the cylinders. Each of the pistons has a top dead center and a bottom dead center at a position symmetrical to the cylinder rotation center, and a cylinder port provided on the side opposite to the piston hole of the piston hole is selectively used as the cylinder rotates. In a piston pump or motor that communicates between two high-pressure or low-pressure ports and allows fluid to enter and exit from the high-pressure or low-pressure port, the top that opens to the cylinder port that passes through the top dead center at the top dead center position. A dead center side opening hole, and a bottom dead center side opening hole that opens to a cylinder port that passes through the bottom dead center at the bottom dead center position, the top dead center side A top dead center side check valve capable of supplying fluid only from the mouth hole to the high pressure side port, and a bottom dead center side capable of supplying fluid only from the bottom dead center side opening hole to the high pressure side port The problem described above has been solved by providing a piston pump or motor having a check valve.

  That is, in the present invention, the pressure oil from the top dead center or bottom dead center opening hole is returned to the high pressure side port instead of the low pressure side through the check valve. Therefore, when the closing pressure at the top dead center or the bottom dead center becomes higher than the pressure at the high pressure side port, the check valve is opened and flows into the high pressure side port, and the closing pressure is added to the operating pressure at the high pressure side port. Only the pressure plus the operating pressure (for example, 0.01 to 0.5 MPa) increases. Further, the confining pressure when operating at a low pressure is similarly low. The bottom dead center is a position where the volume in the piston chamber formed by the piston hole and the piston is maximized, and the top dead center is a position where the volume in the piston chamber is minimized.

  The number of pistons of a general piston pump or motor is set to an odd number, and the phase of the piston chamber is shifted between the top dead center and the bottom dead center. Moreover, it can be set as the position which does not short-circuit a high voltage | pressure side port and a low voltage | pressure side port via a piston chamber. Therefore, in the invention according to claim 2, instead of the top dead center side and bottom dead center side check valves, the communication path that communicates the top dead center side opening hole and the bottom dead center side opening hole. And a check valve capable of supplying fluid only from the communication passage to the high-pressure side port so that the high-pressure side port and the low-pressure side port do not communicate with each other via the piston chamber and the communication passage. Provided piston pump or motor.

  That is, by connecting the top dead center side opening hole and the bottom dead center side opening hole, high pressure oil at the top dead center is supplied to the bottom dead center side. The pressure oil in the communication hole is supplied to the cylinder chamber, and the pressure in the cylinder chamber at the bottom dead center is increased more gradually. Needless to say, the high and low pressure ports need not be short-circuited at the top dead center and the bottom dead center. In the first aspect of the present invention, check valves are provided on the top dead center side and the bottom dead center side, respectively. In the second aspect of the present invention, a check connecting the communication passage and the high pressure side port is provided. The same effect can be achieved with a single valve.

  Also, some piston pumps or motors are not only rotated in one direction but also rotated in both directions. In such a case, in the invention according to claim 3, the cylinder is a piston pump or a motor capable of rotating in both directions, and a shuttle valve is provided between the two ports and the outlet of the check valve, The shuttle valve shuts off the two ports, but is connected to the check valve outlet and the high pressure side port, and is configured to shut off the check valve outlet and the low pressure side port. I will provide a.

  In other words, by providing a shuttle valve at the outlet of the check valve, in the case of a double-rotating hydraulic motor or double-rotating pump, the top dead center or bottom dead center communication hole, regardless of which port becomes high pressure Since it communicates with the high pressure side port, the confining pressure can flow out to the high pressure side regardless of the rotational direction.

  More specifically, in the invention according to claim 4, the piston pump or the motor includes a pintle fixed in a main body, a cylinder that is rotatable on an outer periphery of the pintle, and a radial to the cylinder. A plurality of opened piston holes, a cylinder port communicating with each of the piston holes and opening on an inner periphery of the cylinder on the pintle side, and the pintle cylinder surface with which the cylinder port selectively communicates with the rotation of the cylinder Two pintle ports provided above, and a piston that is inserted into the piston hole and is movable in a radial axis direction that forms a piston chamber. By sliding a partial cylindrical surface provided at the tip of a shoe slidably coupled to the piston chamber side to the inner peripheral surface of the cam ring, A radial piston pump or motor that expands and contracts a stone chamber to act as a pump or motor, wherein the two pintle ports are either the high-pressure side port or the low-pressure side port, and the top dead center Provided is a radial piston pump or motor in which a side opening hole and the bottom dead center side opening hole are respectively provided between the two pintle ports.

  Thereby, in the radial piston pump or the motor, the confining pressure at the top dead center and the bottom dead center can be released to the high pressure port side.

  In the invention described in claim 5, the check valve and the shuttle valve are a radial piston or a motor provided in the pintle.

  Furthermore, in the invention according to claim 6, the piston pump or the motor is concentric in the axial direction of the cylinder, a drive shaft that is rotatable with respect to the main body, a cylinder that rotates around the drive shaft, and the cylinder. A plurality of piston holes opened in the cylinder, a cylinder port communicating with each of the piston holes and opening at an end surface on the side opposite to the piston of the cylinder, a valve plate slidingly contacting the cylinder end surface, and the cylinder port rotating the cylinder Two flange-shaped valve ports provided on the valve plate sliding contact surface selectively communicated with each other, and a piston inserted into the piston hole and movable in the axial direction to form a piston chamber. As the cylinder rotates, the tip of the shoe coupled to the piston chamber side opposite to the piston slides on the swash plate or connects to the swash plate or axle The piston chamber is expanded and contracted to perform a pump or motor action, and the two valve ports are either the high-pressure side port or the low-pressure side port. An axial piston pump or a motor is provided in which the top dead center side opening hole and the bottom dead center side opening hole are respectively provided between the two valve ports.

  Thereby, even if it exists in an axial piston pump or a motor, the confinement pressure in a top dead center and a bottom dead center can be relieved to the high pressure port side.

  In the case of a one-way rotary pump, the high-pressure side port is constant. Accordingly, in the invention according to claim 7, there is provided a piston pump in which the cylinder is a one-way rotating piston pump, wherein the low pressure side port is a suction port and the high pressure side port is a discharge port.

  According to the present invention, the pressure oil from the top dead center or bottom dead center opening hole is returned to the high-pressure side port through the check valve, and the confining pressure at the top dead center or bottom dead center is high. Only the working pressure of the side port (high pressure side port pressure + check valve cracking pressure + pressure loss in the communication passage, etc.) can be increased. At this time, the pump or the motor generates noise corresponding to the operating high-pressure port pressure, but in high-pressure operation, the generation of noise due to confinement is not noticeable. Further, the confining pressure when operating at a low pressure is similarly low.

  Thus, in the present invention, since there is no generation of high pressure due to confinement at the top dead center or bottom dead center, noise is low, and further, the top dead center or bottom dead center is long. Since the pressure in the cylinder chamber is gradually changed, the escape groove can be lengthened, and the pressure in the cylinder chamber can be prevented from suddenly rising and falling, resulting in lower noise. Also, the pressure loss is about the operating pressure of the check valve, and the energy loss due to the pressure loss is small. Furthermore, no pressure adjustment is required, and flow at low speed due to load pressure can be prevented. Further, there is no need to set the pressure, and the influence of the pressure condition is small. In addition, there is little generation of surge pressure and the like, and operation is reliable with a simple structure.

  In the invention according to claim 2, the top dead center side opening hole and the bottom dead center side opening hole are communicated, and high pressure oil at the top dead center is supplied to the bottom dead center side. Since the cylinder chamber pressure is gradually increased, not only is it closed, but cavitation during expansion is prevented, and noise generation is suppressed by cavitation. Further, since only one check valve connecting the communication path and the high-pressure side port is required, the size and weight are reduced.

  Further, in the invention described in claim 3, a shuttle valve is provided at the outlet of the check valve, and a communication hole at the top dead center or the bottom dead center is used regardless of which port is at a high pressure as in the use of a hydraulic motor. Can communicate with the high-pressure side port and discharge the confining pressure to the high-pressure side regardless of the direction of rotation. Therefore, even with a bi-rotary piston pump or motor, it can be closed by top dead center, bottom dead center, etc. Generation of noise can be reduced.

  Further, in the invention according to claim 4, since the radial piston pump or the motor, in which the pistons are radially arranged on the rotating cylinder, the top dead center and the closing pressure at the bottom dead center are released to the high pressure port side. A low noise radial piston pump or motor is provided. Furthermore, in the invention according to claim 5, since the check valve and the shuttle valve are provided in the pintle which is a relatively large part in the radial piston, it is not necessary to enlarge the main body.

  Furthermore, in the invention described in claim 6, the axial piston pump or motor in which the piston is arranged concentrically in the axial direction of the rotating cylinder or the motor can release the confining pressure at the top dead center and bottom dead center to the high pressure port side. Therefore, a low noise axial piston pump or motor is provided.

  Further, the invention according to claim 7 can be easily applied to various piston pumps or motors, such as a low-pressure side port as a suction port and a high-pressure side port as a discharge port. It became a thing.

    A case of a double-rotating radial piston pump according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a radial piston pump according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. In FIGS. 1 and 2, a double-rotating radial piston pump 100 has a cylindrical pintle 2 in which one end 2 a is press-fitted and fixed in a fixing hole 1 a of the main body 1, and the other 2 b projects into an eccentric hole 1 b opened in the main body 1. Yes. The protrusion 2b of the pintle 2 that is a rotation support shaft is provided with a first pintle port 11 that opens in the upper half side in the radial direction and a second pintle port 12 that opens in the lower half side. Each port passes through the two first and second communication passages 11a and 12a, which are opened in the axial direction in the pintle, and opens to the upper side when viewed in the radial direction of the press-fit fixing portion 2a. It is connected to a first external port 13 and a second external port 14 provided in the main body 1 through a first intake / exhaust hole 11b and a second intake / exhaust hole 12b that opens downward.

  A cylinder 3 having a sliding surface having the same width as that of the projecting portion is fitted in a rotatable manner on the outer periphery 2d of the projecting portion 2b of the pintle 2 with a slight clearance. A plurality of piston holes 4 extending radially in the radial direction are formed in the cylinder, and the cylinder port 10 opens toward the pintle side. The cylinder port 10 selectively communicates with the first and second pintle ports 11 and 12, respectively. Has been made possible. A piston 5 is inserted into the piston hole 4 so as to be capable of reciprocating in the radial direction, and a piston chamber 4 a is formed by the cylinder port 10, the piston hole 4, and the piston 5.

  A spherical joint 6a of a shoe 6 is fitted inside the piston 5, and the shoe 6 is linked to be swingable. A partial cylindrical surface 7 is formed at the tip which is the other end of the shoe 6. The partial cylindrical surface slides on the inner peripheral surface 8 a of the cam ring 8 disposed outside the shoe, and the outer periphery 2 d of the pintle 2 is deflected together with the cylinder 3. It is designed to rotate with a core. By this rotation, the piston chamber 4a is expanded and contracted so that fluid can be supplied and discharged.

  As shown in FIG. 1, the cylinder 3 extends toward the pintle protrusion 2b and is engaged with the pintle drive shaft 15 by an Oldham coupling 15a. The pintle drive shaft 15 is rotatably supported via a ball bearing 21b in a shaft hole 21a opened in a cover 21 that closes the eccentric hole 1b in the main body 1 while enclosing and fixing the pintle 2 and the cylinder 3. In addition, the code | symbol 21c is a shaft seal, 21d is a snap ring for axial direction fixation. Thereby, the cylinder 3 can be rotated from the outside by the drive shaft 15.

  The cam ring 8 in which the partial cylindrical surface 7 of the shoe 6 is in sliding contact with the inner peripheral surface 8 a is inserted and fixed in the eccentric hole 1 b of the main body 1. In this case, it becomes a fixed capacity pump or a motor. In the case of a variable capacity, for example, the cam ring 8 is supported by an unillustrated capacity adjustment actuator so as to be movable eccentrically with respect to the center of the pintle 2, and the center position of the pintle 2 and the cam ring 8 is eccentric. Or it can be adjusted concentrically. Further, the support ring 22 is engaged with the rear surfaces on both sides of the shoe 6 so that the shoe surface is not separated from the inner peripheral surface 8 a of the cam ring 8. Further, the cam ring 8 and the support ring 22 are supported by the cover 21 so that the relative positions in the axial direction of the pintle 2, the cylinder 3, the cam ring 8, and the like do not shift. The eccentric hole 1b communicates with a drain port 23 provided in the cover 21, and the drain port 23 is opened to a low-pressure drain (not shown).

  In FIG. 2, when the pintle 2 and the cylinder 3 are rotated clockwise (in the direction of the arrow), the piston chamber 4a is gradually expanded in the lower half, and the second external port 14, the second intake / exhaust hole 12b, the second communication passage 12a, the second Fluid is sucked through the 2-pintle port 12 and the cylinder port 10. At this time, the second external port or the like becomes a suction port and forms a low-pressure side port.

  On the other hand, in the upper half, the piston chamber 4a is gradually reduced, and fluid is discharged (discharged) through the cylinder port 10, the first pintle port 11, the first communication passage 11a, the first intake / exhaust hole 11b, and the first external port 14. ) At this time, the first external port or the like becomes a discharge port and forms a high-pressure side port. If the direction of rotation is reversed, the directions are reversed. In addition, the top or bottom dead center of the piston is sandwiched between the first and second pintle ports, and the first and second pintle ports have a length that does not short-circuit between the first and second pintle ports. Grooves are provided. Since this configuration is the same as that of a general radial piston pump, detailed description thereof is omitted.

  In the present embodiment, in particular, in the middle of the first and second pintle ports 11 and 12 of the pintle 2, that is, at the bottom dead center (left side in FIG. 2) of the piston 5 where the internal volume of the piston chamber 4a is maximum. A top dead center opening hole 42 is opened at the top dead center (right side in FIG. 2) of the piston 5 where the inner volume of the dead center opening hole 41 and the piston chamber 4a is minimized. Yes. An axial flow path 44 is formed along the pintle axis at a substantially intermediate position of the communication path 43, and a check valve 45 is provided on the communication path 43 side so that the fluid does not flow back.

  A shuttle valve 50 is provided at the outlet 46 of the check valve 45. The shuttle valve 50 is provided with a first valve seat 51 and a second valve seat 52 that are opposed to each other, and a branch port 53 is provided by branching from the center between the valve seats. Further, the branch port is connected to the outlet 46 of the check valve 45. It is connected. A valve stem 54 is provided so as to be movable between the valve seats. Conical seat surfaces 55 and 56 are formed on both sides of the valve stem so as to be seated on the valve seat and to be sealed. Length that cannot be seated. Notch grooves 57 and 58 are provided on the outer peripheral side from the seating position on the seat surface, and communicate with the branch holes. Further, the central hole 59 of the first valve seat 51 communicates with the first intake / exhaust hole 11b, and the central hole 60 of the second valve seat 52 communicates with the second intake / exhaust hole 12b. The first valve seat can be removed, and the valve stem 54 can be easily assembled and disassembled. Needless to say, the shuttle valve may be of a ball type or other generally known type.

  Thereby, the one where the pressure in the central holes 59, 60 of the first and second valve seats is higher pushes the valve stem 54, presses the seat surface (55, 56) against the opposite valve seat (51, 52), and seals. The branch port 53 and the central hole on the high pressure side are communicated with each other through the notch grooves (57, 58). Therefore, the shuttle valve 50 shuts off the first and second intake / exhaust holes (ports), but communicates the outlet 46 of the check valve 45 and the high pressure side port, and shuts off the check valve outlet and the low pressure side port. Has been.

  Therefore, for example, as described above, in FIG. 2, when the cylinder 3 is rotated in the direction of the arrow, the second external port 14 and the like become the suction port, the low-pressure side port is formed, and the first external port 13 and the like become the discharge port. Forming a high-pressure side port. At this time, the shuttle valve 50 includes the outlet 46 of the check valve 45, the notch groove 57, the central hole 59 of the first valve seat 51, the first intake / exhaust hole 11b, and the first external port (discharge / high pressure side) 13. In communication, the confining pressure at the top dead center or the bottom dead center is released to the first external port (high pressure side) 13.

  In the case of reverse rotation, the first external port 13 and the like serve as a suction port and form a low pressure side port, and the second external port 14 and the like serve as a discharge port and form a high pressure side port. At this time, the shuttle valve 50 includes the outlet 46 of the check valve 45, the notch groove 58, the central hole 60 of the second valve seat 52, the second intake / exhaust hole 12 b, and the second external port (discharge / high pressure side) 14. In communication, the confining pressure at the top dead center or the bottom dead center is released to the second external port (high pressure side) 14. In this way, the confining pressure can always be released to the high pressure side regardless of the rotation direction. Also, the capacity of the communication passage 43, etc., and the confining pressure (lower than the high-pressure side port) prevent cavitation when the cylinder chamber is expanded, generate preload in the cylinder chamber, prevent sudden pressure entry, It becomes noise.

  In this radial piston pump, an example of the operation in the closed position will be described in detail. FIGS. 3 to 9 are schematic views showing the position and state of the piston chamber at the top dead center and bottom dead center positions in the strokes of the first to sixth states. In each figure, the left side is the top dead center and the right side is the bottom dead center position, and the respective symbols are given the same symbols as described above. Further, the rotation direction is right rotation (arrow direction) in FIG. 2, and the piston moves rightward. First, in FIG. 3, the top dead center side (the right side in FIG. 2) is the end position of the discharge stroke, the cylinder port 10 communicates with the first pintle port (high pressure) 11 and the high pressure side whisker groove 71, and the top dead center opening hole. 42 is not in communication, and on the bottom dead center side (left side in FIG. 2), the cylinder port 10 communicates with the second pintle port (low pressure) 12 during the intake stroke, and the bottom dead center opening hole 41 is closed. Has been. In this case, there is no confinement and cavitation.

  In FIG. 4, the top dead center side cylinder port 10 communicates with the high pressure side whisker groove 71 and the top dead center opening hole 42, and on the bottom dead center side, the cylinder port 10 is connected to the second pintle port 12 and the low pressure side. It communicates with the beard groove 74. In this case, no abnormal pressure is generated from the high pressure side whisker groove 71 or the top dead center opening hole 42 through the check valve 45 and the shuttle valve 50 to the first pintle port 11 side even if the trapping occurs.

  In FIG. 5, the top dead center cylinder port 10 communicates only with the top dead center opening hole 42, and the bottom dead center cylinder port 10 communicates with the low pressure side whisker groove 74. In this case, the confining pressure escapes from the top dead center opening hole 42 to the first pintle port 11 side through the check valve 45 and the shuttle valve 50.

  In FIG. 6, the top dead center side cylinder port 10 communicates with the low pressure side whisker groove 72, and the bottom dead center side cylinder port 10 communicates with the low pressure side whisker groove 74 and the bottom dead center opening hole 41. In this case, both sides are sucked and there is no cavitation. When moving from FIG. 5, the top dead center side is connected to the low pressure side without becoming an abnormal pressure due to confinement, so that the pressure fluctuation can be reduced and the noise can be reduced. In addition, the communication hole 43 is maintained at a confining pressure (a pressure lower than that of the high-pressure side port), and it is possible to apply a preload to the cylinder chamber to prevent cavitation.

  FIG. 7 shows a suction stroke in which the top dead center side cylinder port 10 communicates with the low pressure side whisker groove 72 and the second pintle port 12, and the bottom dead center side cylinder port 10 communicates with the bottom dead center opening hole 41 for compression. When it turns, the confining pressure escapes from the bottom dead center opening hole to the first pintle port side through the check valve 45 and the shuttle valve 50, and no abnormal pressure is generated. At the time of movement from FIG. 6, the bottom dead center side changes from inhalation to confinement, but the volume of the communication path is also added and cavitation during inhalation is small.

  In FIG. 8, the top dead center side cylinder port 10 communicates with the second pintle port 12, and the bottom dead center side cylinder port 10 communicates with the bottom dead center opening hole 41 and the high pressure side whisker groove 73, and the discharge (high pressure) stroke. Become. In this case, even if the closure occurs, the high pressure side whisker groove 73 or the bottom dead center opening hole 41 escapes to the first pintle port 11 side through the check valve 45 and the shuttle valve 50, and no abnormal pressure is generated.

  In FIG. 9, the top dead center side cylinder port 10 communicates with the second pintle port 12 for a suction (low pressure) stroke, and the bottom dead center cylinder port 10 communicates with the first pintle port 11 for a discharge (high pressure) stroke. . At the time of movement from FIG. 8, the bottom dead center side is connected to the high pressure side with almost the same pressure without being an abnormal pressure due to confinement, so that the pressure fluctuation can be reduced and the noise can be reduced.

  As described above, in the present embodiment, the occurrence of abnormal pressure due to the closure of the cylinder chamber 4a at the top dead center and the bottom dead center is prevented, the outflow noise to the low pressure side of the abnormal pressure is eliminated, and the communication path 43 enables fluid replenishment when the cylinder chamber is expanded, thereby reducing pressure fluctuations and noise. 3 to 9 show an example, and it goes without saying that there are various forms depending on the number and size of the pistons.

  Next, an embodiment in which the present invention is used for an axial piston pump will be described. 10 is a longitudinal sectional view of a swash plate type axial piston pump according to an embodiment of the present invention, and FIG. 11 is a sectional view taken along line AA of FIG. In addition, about the structure similar to the radial piston pump mentioned above, the same code | symbol is attached | subjected and a part of description is abbreviate | omitted. 10 and 11, the axial piston pump 101 has a drive shaft 15 'rotatably supported between a main body 1' and a cover 21 '. A cylinder 3 'is splined to the drive shaft so that it can be rotated. A plurality of piston holes 4 are formed concentrically in the axial direction of the cylinder 3 ′, and cylinder ports 10 are provided at the bottoms of the piston holes. A valve plate 2 'in which the cylinder end surface 3a is in sliding contact is attached to the cover 21' side. As shown in FIG. 11, the valve plate 2 'is provided with two bowl-shaped first valve port 11 and second valve port 12, which are communicated with a first external port and a second external port (not shown), respectively. . A piston 5 'is inserted into the piston hole 4 to form a piston chamber 4a. A shoe 6 'is provided at the tip of the piston 5', and the shoe slides on the sliding contact surface 8a 'of the swash plate 8' provided on the inner end surface of the main body in accordance with the rotation of the cylinder so as to reciprocate the piston. Expands and contracts and performs pumping.

  In FIG. 11, when the cylinder 3 ′ is rotated to the right (in the direction of the arrow), the piston chamber 4 a gradually expands in the right half, and fluid flows into the piston chamber through the second external port, the second valve port 12, and the cylinder port 10. Is inhaled. At this time, the second valve port 12 or the like becomes a suction port and forms a low-pressure side port.

  On the other hand, in the left half, the piston chamber 4a is gradually reduced, and fluid is discharged (discharged) through the cylinder port 10, the first valve port 11, and the first external port. At this time, the first valve port 11 or the like becomes a discharge port and forms a high-pressure side port. If the direction of rotation is reversed, the directions are reversed. Also, a relief groove for relaxing the sliding contact surface and pressure fluctuation so as not to short-circuit between the first and second valve ports with the top or bottom dead center of the piston sandwiched between the first and second valve ports. 71, 72, 73, 74 are provided. Since this configuration is the same as that of a general axial piston pump, detailed description thereof is omitted.

  In the present embodiment, in particular, in the middle of the first and second valve ports 11 and 12 of the valve plate 2 ′, the bottom dead center opening hole 41 on the lower side in FIG. 11 and the top dead center opening hole 42 on the upper side in FIG. Are opened, and both opening holes communicate with each other through a communication passage 43. A check valve 45 is provided at a substantially intermediate position of the communication passage 43. A shuttle valve 50 is provided at the outlet 46 of the check valve 45. The shuttle valve 50 is the same as described above, and the central hole 59 of the first valve seat is connected to the first valve port 11, and the central hole 60 of the second valve seat is connected to the second valve port 12.

  Therefore, as described above, for example, when the cylinder 3 'is rotated in the direction of the arrow, the second valve port 12 becomes a suction port and forms a low pressure side port, and the first valve port 11 becomes a discharge port and the high pressure side. Form a port. At this time, the shuttle valve 50 communicates the first valve port (discharge / high pressure side) 13 with the check valve so that the closing pressure at the top dead center or the bottom dead center is released to the first valve port 13. The

  In the case of reverse rotation, the first valve port 11 and the like serve as a suction port and form a low pressure side port, and the second valve port 12 and the like serve as a discharge port and form a high pressure side port. At this time, the shuttle valve 50 communicates the second valve port (discharge / high pressure side) 12 with the check valve 45, and the closing pressure at the top dead center or the bottom dead center is set to the second valve port (high pressure side) 12. To escape. In this way, the confining pressure can always be released to the high pressure side regardless of the rotation direction.

  As described above, the axial piston pump also has the same operations and effects as those of the radial piston pump described above, and a detailed description thereof will be omitted. In the embodiment, the case of the double-rotating radial piston pump and the axial piston pump has been described, but it goes without saying that the same applies to the double-rotating radial or axial piston motor.

  For example, FIG. 12 is a circuit explanatory diagram corresponding to FIG. 11 of the bi-directionally rotating axial piston pump described above. Similarly, as shown in FIG. 13, in the case of an axial piston pump that rotates in one direction to the right, the shuttle valve 50 is unnecessary, and a check valve 45 is connected to the top dead center and bottom dead center opening holes 42 and 41, respectively. The check valve outlet 46 may be connected to the discharge (high pressure) port 11 side. Further, in the case of an axial piston pump rotating in both directions, as shown in FIG. 14, a check valve 45 is provided at the top dead center and the bottom dead center opening holes 42 and 41, and a shuttle valve 50 is provided at the check valve outlet 46, respectively. The shuttle valve outlet ports 59 and 60 may be connected to the first and second valve (pintle) ports 11 and 12 side.

  Further, in the case of providing a communication path with an axial piston pump that rotates in one direction to the right, as shown in FIG. 15, the top dead center and bottom dead center opening holes 42 and 41 are communicated with each other through the communication path 43, and the communication path 43 Various patterns are possible, such as connecting the check valve 45 to the outlet and connecting the outlet 46 of the check valve to the discharge (high pressure) port 11 side.

1 is a longitudinal sectional view of a radial piston pump according to an embodiment of the present invention. It is the sectional view on the AA line of FIG. It is a schematic diagram which shows the position and state of a piston chamber in the top dead center and bottom dead center position concerning embodiment of this invention, and is a schematic diagram which shows a 1st state. It is a schematic diagram which shows a 2nd state similarly. It is a schematic diagram which shows a 3rd state similarly. It is a schematic diagram which shows a 4th state similarly. It is a schematic diagram which shows a 5th state similarly. It is a schematic diagram which shows a 6th state similarly. It is a schematic diagram which shows a 7th state similarly. It is a longitudinal cross-sectional view of the axial piston pump which concerns on embodiment of this invention. It is the sectional view on the AA line of FIG. FIG. 12 is a circuit explanatory diagram of FIG. 11. It is circuit explanatory drawing which shows other 1st Embodiment of this invention. It is circuit explanatory drawing which shows other 2nd Embodiment of this invention. It is circuit explanatory drawing which shows other 3rd Embodiment of this invention.

Explanation of symbols

1, 1 'body 2, 2' pintle, valve plate 3, 3 'cylinder 4 piston hole 4a piston chamber 5, 5' piston 6, 6 'shoe 7 partial cylindrical surface 8 cam ring 8' swash plate 8a cam ring inner peripheral surface 10 Cylinder port 11 1st pintle (valve) port (high or low pressure port)
12 Second pintle (valve) port (high or low pressure port)
DESCRIPTION OF SYMBOLS 15 Drive shaft 41 Bottom dead center opening hole 42 Top dead center opening hole 43 Communication path 45 Check valve 46 Check valve exit 50 Shuttle valve 100 Radial piston pump 101 Axial piston pump

Claims (7)

A piston chamber is formed by pistons capable of entering and exiting a plurality of piston holes provided at equal intervals in the rotating cylinder, and the pistons are sequentially reciprocated so that the center of rotation of the cylinders is rotated every rotation of the cylinders. Each of the pistons has a top dead center and a bottom dead center at symmetrical positions, and a cylinder port provided on the side opposite to the piston of the piston hole is selectively connected to the high pressure or low pressure 2 as the cylinder rotates. In a piston pump or motor that communicates between two ports and allows fluid to enter and exit the high pressure or low pressure port, a top dead center side opening hole that opens to a cylinder port that passes through the top dead center at the top dead center position And a bottom dead center side opening hole that opens to a cylinder port that passes through the bottom dead center at the bottom dead center position, and the high pressure from the top dead center side opening hole A top dead center side check valve capable of supplying fluid only to the port, and a bottom dead center side check valve capable of supplying fluid only from the bottom dead center side opening hole to the high pressure side port, A piston pump or motor characterized by comprising: Instead of the top dead center side and bottom dead center side check valves, a communication path communicating the top dead center side opening hole and the bottom dead center side opening hole, and from the communication path to the high pressure side port only 2. A check valve capable of supplying fluid, wherein the high-pressure side port and the low-pressure side port are not communicated with each other via the piston chamber and the communication passage. Piston pump or motor. The cylinder is a piston pump or a motor that can rotate in both directions, and a shuttle valve is provided between the two ports and the outlet of the check valve, and the shuttle valve blocks between the two ports, The piston pump or motor according to claim 1 or 2, wherein an outlet of the check valve and a high-pressure side port are communicated with each other, and an outlet of the check valve and a low-pressure side port are shut off. The piston pump or motor includes a pintle fixed in a main body, a cylinder that is rotatable on an outer periphery of the pintle, a plurality of piston holes radially formed in the cylinder, and communicates with the piston holes. A cylinder port that opens to the inner periphery of the pintle side of the cylinder, two pintle ports provided on the pintle cylinder surface that the cylinder port selectively communicates with the rotation of the cylinder, and the piston hole. A piston which is inserted and forms a piston chamber and is movable in a radial axis direction, and is provided at the tip of a shoe which is swingably connected to the piston chamber side of the piston as the cylinder rotates. The piston chamber is expanded / contracted by sliding the partial cylindrical surface formed on the inner peripheral surface of the cam ring, and acts as a pump or a motor. A radial piston pump or a motor, wherein the two pintle ports are either the high-pressure side or the low-pressure side port, and the top dead center side opening hole and the bottom dead center side opening hole are The radial piston pump or motor according to claim 1, wherein the radial piston pump or the motor is provided between two pintle ports. The radial piston or motor according to claim 4, wherein the check valve and the shuttle valve are provided in the pintle. The piston pump or the motor includes a drive shaft that is rotatable with respect to a main body, a cylinder that rotates around the drive shaft, a plurality of piston holes that are concentrically opened in the axial direction of the cylinder, A cylinder port that communicates with the piston hole and opens at the end surface on the side opposite to the piston of the cylinder; a valve plate that slidably contacts the cylinder end surface; and the valve plate sliding contact that the cylinder port selectively communicates with the rotation of the cylinder. Two flange-shaped valve ports provided on the surface, and a piston that is inserted into the piston hole and is axially movable so as to form a piston chamber. The piston chamber is expanded or contracted by sliding the tip of the shoe connected to the piston chamber side against the swash plate or connecting it to the swash plate or the axle. An axial piston pump or motor adapted to act as a pump or motor, wherein the two valve ports are either the high-pressure side port or the low-pressure side port, and the top dead center side opening hole and the bottom port 4. The axial piston pump or motor according to claim 1, wherein a dead center side opening hole is provided between each of the two valve ports. The said cylinder is a piston pump of one direction rotation, Comprising: The said low voltage | pressure side port is an intake port, The said high voltage | pressure side port is a discharge port, The 1st or 2 or 4 or 5 or 6 characterized by the above-mentioned. Piston pump.

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