JP2014111914A - Hydraulic pump motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial hydraulic pump motor capable of improving efficiency by reducing erosion (cavitation damage) or noise caused by aeration which occurs when shifting from a high-pressure process to a low-pressure process.SOLUTION: The hydraulic pump motor comprises: a residual pressure regeneration circuit 30; and a residual pressure release circuit 60. After a cylinder bore 25f is released from a communicated state with a valve plate discharge port PB2 and before the cylinder bore 25f is communicated to a valve plate suction port PB1, the residual pressure regeneration circuit 30 transfers residual pressure within the cylinder bore 25f into the cylinder bore at a bottom dead center side which is released from a communicated state with the valve plate suction port PB1. In the residual pressure release circuit 60, residual pressure release holes 61a, 61b are provided which are communicated to the cylinder bore 25f after the cylinder bore 25f is communicated to the residual pressure regeneration circuit 30 and residual pressure is reduced and before the cylinder bore 25f is communicated to the valve plate suction port PB1, and a flow rate control valve V10 is included for adjusting a hydraulic fluid flow rate to be extracted from the residual pressure release holes 61a, 61b to the side of a tank 64 in accordance with a swash plate angle and a rotation speed.

Description

  The present invention relates to an axial type hydraulic pump / motor (hydraulic pump or hydraulic motor) that can reduce erosion (erosion) and noise caused by aeration that occur when shifting from a high pressure process to a low pressure process, and increase efficiency. Is.

  2. Description of the Related Art Conventionally, in construction machines and the like, an axial hydraulic piston pump driven by an engine and an axial hydraulic piston motor driven by high-pressure hydraulic oil are frequently used.

  For example, an axial hydraulic piston pump is a cylinder in which a plurality of cylinders are provided that rotate integrally with a rotary shaft that is rotatably provided in a case, and that are separated in the circumferential direction and extend in the axial direction. A block, a plurality of pistons that are slidably inserted into the cylinders of the cylinder block, move in the axial direction as the cylinder block rotates, and suck and discharge hydraulic oil, and a case and a cylinder block end face And a valve plate in which a suction port and a discharge port communicating with each cylinder are formed. In this hydraulic pump, when the drive shaft is driven to rotate, the cylinder block rotates together with the operating shaft in the case, the piston reciprocates in each cylinder of the cylinder block, and the hydraulic oil sucked into the cylinder from the suction port is drawn. Pressurized by the piston and discharged to the discharge port as high pressure hydraulic oil.

  Here, when the cylinder port of each cylinder communicates with the suction port of the valve plate, there is a suction process in which the piston moves from the start port to the end of the suction port in the direction protruding from the cylinder and sucks hydraulic oil into the cylinder from the suction port. Done. On the other hand, when the cylinder port of each cylinder communicates with the discharge port, a discharge process is performed in which the piston moves in the direction of entering the cylinder from the start end to the end of the discharge port to discharge the hydraulic oil in the cylinder into the discharge port. Is called. Then, by rotating the cylinder block so as to repeat the suction process and the discharge process, the hydraulic oil sucked into the cylinder from the suction port in the suction process is pressurized in the discharge process and discharged to the discharge port.

International Publication No. 2009/037994 JP 2000-64950 A

  By the way, in the above-described conventional hydraulic pumps or the like, the cylinder in which the hydraulic oil is discharged through the discharge port of the valve plate in the discharge process is at a high pressure, and when the cylinder port of each cylinder communicates with the suction port, The hydraulic oil having a high pressure in the cylinder suddenly flows into the low-pressure suction port via the suction port, and a large pressure fluctuation occurs. As a result, aeration in which air is mixed in the state of fine bubbles is generated in the hydraulic oil in the suction port, and erosion and noise due to this aeration are generated, resulting in a reduction in efficiency.

  For this reason, for example, in Patent Document 1, a residual pressure release hole is provided, and hydraulic fluid that is at a high pressure in the cylinder is returned to the tank when shifting from the discharge process to the suction process. As a result, the change in hydraulic oil from the discharge process to the suction process becomes gradual, and when the cylinder port communicates with the suction port, the hydraulic oil pressure in the cylinder and the hydraulic oil pressure in the suction port are made the same. .

  However, since the residual pressure release hole has a fixed opening degree, that is, the opening area and the opening time are fixed, the residual pressure in the cylinder is changed by the change in the inclination angle (swash plate angle) and the rotational speed of the swash plate of the hydraulic pump. It does not correspond to the case where the oil amount changes. As a result, depending on the swash plate angle and rotational speed, when the cylinder port communicates with the suction port, the residual pressure in the cylinder does not necessarily decrease to the hydraulic oil pressure in the suction port, and aeration occurs. There was a case. Then, erosion and noise due to this aeration are generated, and the efficiency may be further reduced.

  In Patent Document 2, a residual pressure release hole communicating with the suction port is provided, and the opening of the residual pressure release hole is made variable according to the swash plate angle and the rotation speed. However, the residual pressure release hole is directly connected to the suction port. In this case, aeration is generated in the hydraulic oil that has escaped from the cylinder through the residual pressure release hole, and the generated hydraulic oil is directly returned to the suction port, which causes erosion and noise due to aeration. Will do. And efficiency will also fall.

  The present invention has been made in view of the above, and is an axial type hydraulic that can reduce erosion (erosion) and noise caused by aeration that occur when shifting from a high pressure process to a low pressure process, and can increase efficiency. An object is to provide a pump motor.

  In order to solve the above-described problems and achieve the object, a hydraulic pump / motor according to the present invention has a cylinder block in which a plurality of cylinder bores are formed around a rotation shaft, which has a high-pressure side port and a low-pressure side port. An axial type hydraulic pump / motor that slides against the valve plate and controls the amount of reciprocation of the piston in each cylinder bore by the inclination of the swash plate, wherein the top dead center side cylinder bore is connected to the high pressure side port. The residual pressure in the top dead center cylinder bore is transmitted to the bottom dead center cylinder bore from which the communication with the low pressure side port is released after the communication state is released and before communication with the low pressure side port. The residual pressure regeneration circuit and the top dead center side cylinder bore communicate with the residual pressure regeneration circuit and reduce the residual pressure until the top dead center side cylinder bore communicates with the low pressure side port. A residual pressure relief circuit having a flow rate control valve that adjusts the flow rate of hydraulic fluid that is provided to the tank side from the residual pressure relief hole according to the swash plate angle and rotation speed. It is characterized by that.

  Further, in the hydraulic pump / motor according to the present invention, in the above invention, after the residual pressure in the top dead center side cylinder bore is reduced through the residual pressure release hole, the hydraulic pump / motor is communicated with the low pressure side port. A timing adjustment hole for communicating the top dead center side cylinder bore and the low pressure side port to the top dead center side cylinder bore from the high pressure side port via the timing adjustment hole according to a swash plate angle and a rotational speed. A timing adjustment circuit having a timing adjustment flow rate control valve for adjusting the flow rate of hydraulic oil moving inward is provided.

  In the hydraulic pump / motor according to the present invention as set forth in the invention described above, the residual pressure regeneration circuit adjusts the flow rate of hydraulic oil discharged from the top dead center cylinder bore in accordance with the swash plate angle and the rotational speed. A residual pressure flow control valve is provided.

  In the hydraulic pump / motor according to the present invention, the flow control valve, the timing adjustment flow control valve, and the residual pressure flow control valve are controlled by the same control signal. To do.

  Further, in the hydraulic pump / motor according to the present invention, in the above invention, a plurality of the top dead center side port and the bottom dead center side port of the residual pressure regeneration circuit and / or the residual pressure release hole are provided, In addition, it is formed by being shifted along the traveling direction of the cylinder bore.

  The hydraulic pump / motor according to the present invention is the hydraulic pump / motor according to the above-described invention, wherein the cylinder bore communicates with the high pressure side port immediately before each cylinder bore communicates with the high pressure side port of the valve plate, and the bottom dead center side. The high pressure side port and the inside of the bottom dead center side cylinder bore are connected to the bottom dead center cylinder bore side after the cylinder bore is released from the communication state with the low pressure side port until the cylinder bore communicates with the self-pressure throttle. An elongated hole that is temporarily communicated through the provided notch groove is provided, the elongated hole transmits a high pressure in the elongated hole on the cylinder bore side to the cylinder bore when communicating, and an elongated hole on the cylinder bore side when not communicated And a long hole circuit having a length capable of restoring the internal pressure to the pressure on the high-pressure side port before communication with the next cylinder bore.

  According to the present invention, the residual pressure in the top dead center side cylinder bore is reduced between the time when the top dead center side cylinder bore is disconnected from the communication state with the high pressure side port and before communication with the low pressure side port. A residual pressure regeneration circuit that transmits to the bottom dead center cylinder bore that has been released from the communication state with the low pressure side port; and the top dead center cylinder bore communicates with the residual pressure regeneration circuit to reduce the residual pressure, and then the low pressure A residual pressure relief hole communicating with the top dead center cylinder bore is provided until the side port is communicated, and the flow rate of hydraulic oil that is drawn from the residual pressure relief hole to the tank side according to the swash plate angle and rotational speed is set. A residual pressure relief circuit with a flow control valve to adjust, and stably reduce the residual pressure in the cylinder bore when shifting from the high pressure process to the low pressure process regardless of changes in the swash plate angle and rotational speed. Therefore, transition from high pressure process to low pressure process Reduce erosion and noise by aeration occurring when that can increase the efficiency.

FIG. 1 is a cross-sectional view showing a schematic configuration of a hydraulic pump according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the hydraulic pump shown in FIG. FIG. 3 is a cross-sectional view of the hydraulic pump shown in FIG. FIG. 4 is a diagram illustrating a configuration in which the sliding surface of the cylinder block with the valve plate is viewed in the −X direction. FIG. 5 is an explanatory diagram for explaining the operation of the residual pressure regeneration circuit shown in FIG. FIG. 6 is a diagram showing the positional relationship between the valve plate and the cylinder bore in the vicinity of the top dead center side. FIG. 7 is a cross-sectional view showing a state in the cylinder bore showing a state in which the swash plate angle is maximized. FIG. 8 is a cross-sectional view showing a state in the cylinder bore showing a state where the swash plate angle is minimized. FIG. 9 is a view showing a configuration in the vicinity of the top dead center of the first modification of the hydraulic pump according to the embodiment of the present invention. FIG. 10 is a diagram showing a configuration in the vicinity of the top dead center of Modification 2 of the hydraulic pump according to the embodiment of the present invention. FIG. 11 is a diagram showing a configuration in the vicinity of the top dead center of the third modification of the hydraulic pump according to the embodiment of the present invention. FIG. 12 is a view showing a configuration in the vicinity of the top dead center of the modified example 4 of the hydraulic pump according to the embodiment of the present invention. FIG. 13 is a cross-sectional view taken along line BB of Modification 5 of the hydraulic pump illustrated in FIG. FIG. 14 is a diagram showing a configuration in which the sliding surface with the valve plate in the cylinder block of Modification 5 is viewed in the −X direction. FIG. 15 is an explanatory diagram for explaining the operation when shifting from the suction process to the discharge process in Modification 5.

  Hereinafter, a hydraulic pump / motor which is an embodiment for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a hydraulic pump according to an embodiment of the present invention. 2 is a cross-sectional view of the hydraulic pump shown in FIG. The hydraulic pump shown in FIGS. 1 and 2 converts engine rotation and torque transmitted to the shaft 1 into hydraulic pressure, and discharges the oil sucked from the suction port P1 from the discharge port P2 as high-pressure hydraulic oil. This is a variable displacement hydraulic pump that can vary the discharge amount of hydraulic oil from the pump by changing the inclination angle a of the swash plate 3.

  Hereinafter, the axis along the axis of the shaft 1 is the X axis, the axis along the inclined central axis that is a line connecting the fulcrum when the swash plate 3 is inclined is the Z axis, the X axis, and the axis orthogonal to the Z axis is Y Axis. The direction from the input side end of the shaft 1 to the opposite end is defined as the X direction.

  The hydraulic pump is connected to the case 2 and the end cap 8 through a shaft 1 rotatably supported by bearings 9a and 9b, and is connected to the shaft 1 through a spline structure 11. The case 2 and the end cap 8 A cylinder block 6 that rotates integrally with the shaft 1, and a swash plate 3 provided between the side wall of the case 2 and the cylinder block 6. The cylinder block 6 is provided with a plurality of piston cylinders (cylinder bores 25) arranged at equal intervals in the circumferential direction around the axis of the shaft 1 and parallel to the axis of the shaft 1. Pistons 5 that can reciprocate parallel to the axis of the shaft 1 are inserted into the plurality of cylinder bores 25.

  A spherical concave sphere is provided at the tip of each piston 5 protruding from each cylinder bore 25. The spherical convex portion of the shoe 4 fits in the spherical concave portion, and each piston 5 and each shoe 4 forms a spherical bearing. Note that the spherical concave portion of the piston 5 is caulked, and separation from the shoe 4 is prevented.

  The swash plate 3 has a flat sliding surface S on the side facing the cylinder block 6. Each shoe 4 slides in a circle or an ellipse while being pressed onto the sliding surface S as the cylinder block 6 rotates in conjunction with the rotation of the shaft 1. Around the axis of the shaft 1, a spring 15 supported by a ring 14 provided on the inner periphery of the cylinder block 6 in the X direction, a movable ring 16 and a needle 17 that are pressed by the spring 15, and a ring that contacts the needle 17. A pressing member 18 is provided. The shoe 4 is pressed against the sliding surface S by the pressing member 18.

  On the side wall of the case 2, two hemispherical bearings 20 and 21 projecting toward the swash plate 3 side are provided at symmetrical positions with the axis of the shaft 1 interposed therebetween. On the other hand, on the side wall side of the case 2 of the swash plate 3, two concave spheres are formed at portions corresponding to the arrangement positions of the bearings 20 and 21, and the bearings 20 and 21 and the two concave spheres of the swash plate 3 are in contact with each other. The bearing of the swash plate 3 is formed by contact. The bearings 20 and 21 are arranged in the Z-axis direction.

  As shown in FIG. 2, the swash plate 3 is inclined in a plane perpendicular to the XY plane with a line connecting the bearings 20 and 21 as an axis (an axis parallel to the Z axis). The inclination of the swash plate 3 is determined by the piston 10 that reciprocates while pressing one end of the swash plate 3 along the X direction from the side wall side of the case 2. The reciprocating motion of the piston 10 causes the swash plate 3 to tilt with a line connecting the bearings 20 and 21 as a fulcrum. Due to the inclination of the swash plate 3, the sliding surface S is also inclined, and the cylinder block 6 rotates as the shaft 1 rotates. For example, as shown in FIGS. 1 and 2, when the inclination angle from the XZ plane is a, when the cylinder block rotates counterclockwise as viewed in the X direction, each shoe 4 is circular on the sliding surface S. Or it slides elliptically, and the piston 5 in each cylinder bore 25 reciprocates along with this. When the piston 5 moves to the swash plate 3 side, oil is sucked into the cylinder bore 25 from the suction port P1 through the valve plate 7. Further, when the piston 5 moves to the valve plate 7 side, the oil in the cylinder bore 25 is discharged from the discharge port P2 through the valve plate 7 as high pressure hydraulic oil. By adjusting the inclination of the swash plate 3, the volume of hydraulic oil discharged from the discharge port P2 can be variably controlled. Note that the inclination angle (swash plate angle) D1 of the swash plate due to the reciprocation of the piston 10 is output to the control unit C10 (see FIG. 3). Moreover, the speed sensor 100 detects the rotational speed D2 of the shaft 1, and outputs it to the control part C10 (refer FIG. 3).

  Here, the valve plate 7 fixed to the end cap 8 side and the rotating cylinder block 6 are in contact with each other via the sliding surface Sa. FIG. 3 is a cross-sectional view of the hydraulic pump shown in FIG. FIG. 4 is a diagram showing a configuration in which the sliding surface Sa with the valve plate 7 in the cylinder block 6 is viewed in the −X direction. The end surface on the sliding surface Sa side of the valve plate 7 shown in FIGS. 3 and 4 and the end surface on the sliding surface Sa side of the cylinder block 6 slide with each other as the cylinder block 6 rotates.

  As shown in FIG. 3, the valve plate 7 has a valve plate suction port PB1 that communicates with the suction port P1, and a valve plate discharge port PB2 that communicates with the discharge port P2. The valve plate suction port PB1 and the valve plate discharge port PB2 are provided on the same arc and have a bowl shape extending in the circumferential direction. On the other hand, as shown in FIG. 4, on the sliding surface Sa side of the cylinder block 6, there are nine cylinder bore 25 ports (cylinder ports 25P) through which the pistons 5 reciprocate, the valve plate suction port PB1 and the valve plate discharge. On the same circular arc in which the port PB2 is arranged, it is provided in a bowl shape at equal intervals. 3 and 4, when the cylinder block 6 rotates clockwise as viewed in the -X direction, a discharge process is performed on the valve plate discharge port PB2 side on the upper side in FIG. The suction process is performed on the lower valve plate suction port PB1 side. Therefore, in this case, the right end side in FIG. 3 is switched from the discharge process to the suction process, and becomes the top dead center where the piston 5 enters the sliding surface Sa side most in the cylinder bore 25. The inside of the cylinder bore 25 is changed from the high pressure state to the low pressure state. Transition to the state. 3 is switched from the suction process to the discharge process, and the piston 5 is the bottom dead center farthest from the sliding surface Sa side in the cylinder bore 25. When the cylinder port 25a passes through the bottom dead center, the low pressure state is shifted to the high pressure state.

  As shown in FIG. 4, the cylinder block 6 is located on a circumference larger than the circumference of the outer wall surface of the cylinder bore 25 and shifted from the outer wall surface of the cylinder bore 25 to the circumference, for example, in the middle of the cylinder bore 25. It has a residual pressure loss port 33a provided on the passing radius. Similarly, a residual pressure loss port 33b is provided at a position shifted circumferentially from the inner wall surface of the cylinder bore 25. The pair of residual pressure loss ports 33a and 33b provided on the sliding surface Sa side is provided for each cylinder bore 25 and communicates with the cylinder bore 25 through oblique communication holes 34a and 34b communicating with the cylinder bore 25.

  As shown in FIG. 3, the valve plate 7 includes a cylinder bore 25 in the vicinity of the top dead center corresponding to the circumference where the residual pressure loss ports 33a and 33b are provided and on the circumference of the suction process side. Residual pressure loss recovery ports 31a and 31b are provided at positions communicating with the cylinder bore 25 immediately after the communication state with the discharge port PB2 is released. Further, the valve plate 7 is located near the bottom dead center corresponding to the circumference where the residual pressure loss ports 33a and 33b are provided and on the circumference on the discharge process side, and the cylinder bore 25 communicates with the valve plate suction port PB1. Residual pressure loss regeneration ports 32a and 32b are provided at positions communicating with the cylinder bore 25 immediately after the state is released. Further, the valve plate 7 is provided with a communication hole 30a for communicating the residual pressure loss recovery ports 31a and 31b and the residual pressure loss recovery ports 32a and 32b. The residual pressure loss recovery ports 31a and 31b and the residual pressure loss recovery port A residual pressure regeneration circuit 30 having 32a and 32b is formed. The residual pressure loss ports 33a and 33b and the residual pressure loss recovery ports 31a and 31b are displaced on the circumference so as to communicate with each other after the residual pressure loss ports 33a and 33b and the residual pressure loss regeneration ports 32a and 32b communicate with each other. The residual pressure regeneration circuit 30 reduces the pressure in the cylinder bore 25 when shifting from the discharge process to the suction process, and boosts the pressure in the cylinder bore 25 that shifts from the suction process to the discharge process.

  Further, the valve plate 7 has a residual pressure loss port 33a, 33b and a residual pressure loss regeneration port 32a, 32b on the circumference through which the cylinder bore 25 passes and before the cylinder bore 25 communicates with the valve plate suction port PB1. Residual pressure release holes 61a and 61b are respectively provided at positions where they communicate after the communication. The residual pressure relief holes 61a and 61b can communicate with the tank 64 (or the space between the valve plate 7 and the case 2) via the communication hole 62, the flow control valve V10, and the communication hole 63. The residual pressure relief holes 61a and 61b, the communication hole 62, the flow control valve V10, the communication hole 63, and the tank 64 form a residual pressure relief circuit 60. The flow rate control valve V10 controls the hydraulic fluid flow rate from the residual pressure relief holes 61a and 61b according to the swash plate angle D1 and the rotational speed D2. For example, when the rotational speed D2 is constant and the swash plate angle D1 is large, the amount of hydraulic oil in the cylinder bore 25 is small, so the oil passage is narrowed. When the rotational speed D2 is constant and the swash plate angle D1 is small, the amount of hydraulic oil in the cylinder bore 25 is large, so the oil passage is opened. The residual pressure release holes 61a and 61b and the flow rate control valve V10 shift from the discharge process to the suction process, and the residual pressure in the cylinder bore 25 after recovery of the residual pressure loss is variable according to the swash plate angle D1 and the rotational speed D2. The pressure is reduced.

  Further, the valve plate 7 has a remaining circumference on the circumference through which the cylinder bore 25 passes and immediately before the cylinder bore 25 communicates with the valve plate suction port PB1, after the residual pressure relief holes 61a and 61b communicate with the cylinder bore 25. A timing adjustment hole 71 having a larger diameter than the pressure loss recovery ports 31a and 31b and the residual pressure release holes 61a and 61b is provided. The timing adjustment hole 71 can communicate with the valve plate suction port PB1 via the communication hole 72, the flow control valve V11, and the communication hole 73. The timing adjustment hole 71, the communication hole 72, the flow rate control valve V11, and the communication hole 73 form a timing adjustment circuit 70. The flow rate control valve V11 controls the hydraulic oil flow rate to the timing adjustment hole 71 according to the swash plate angle D1 and the rotational speed D2. For example, when the rotational speed D2 is constant and the swash plate angle D1 is large, the amount of hydraulic oil in the cylinder bore 25 is small, so that the residual pressure is almost equal to the pressure of the valve plate discharge port PB1 when communicating with the timing adjustment hole 71. Therefore, the oil passage is opened, and the suction process via the timing adjustment hole 71 is started early. Further, when the rotational speed D2 is constant and the swash plate angle D1 is small, the amount of hydraulic oil in the cylinder bore 25 is large, and therefore, when communicating with the timing adjustment hole 71, the residual pressure is compared with the pressure of the valve plate discharge port PB1. Because it is big, squeeze the oil passage. With this timing adjustment hole 71 and the flow rate control valve V11, the timing for shifting to the suction process can be adjusted according to the swash plate angle D1 and the rotational speed D2. In other words, the region of the valve plate suction port PB1 can be varied according to the swash plate angle D1 and the rotation speed D2, and an efficient suction process can be performed.

  Further, the valve plate 7 is provided with a self-pressure restrictor 52 at a position on the circumference where the cylinder bore 25 passes and immediately before the cylinder bore 25 communicates with the valve plate discharge port PB2. In the self-pressure throttle 52, the port on the sliding surface Sa side and the valve plate discharge port PB2 are communicated with each other through an oblique communication hole 53. The pressure in the cylinder bore 25 that shifts from the suction process to the discharge process is further increased by the self-pressure throttle 52 after the residual pressure regeneration through the residual pressure regeneration circuit 30.

(Transition from suction process to discharge process)
As shown in FIG. 5, the nine cylinder bores 25a to 25i are arranged in an annular shape. Here, when the residual pressure loss ports 33af and 33bf of the cylinder bore 25f that have shifted from the discharge process to the suction process on the top dead center side communicate with the residual pressure loss recovery ports 31a and 31b, a high pressure is generated in the communication hole 30a. The residual pressure is temporarily accumulated. Thereafter, the residual pressure loss ports 33aa and 33ba of the cylinder bore 25a that shift from the suction process to the discharge process on the bottom dead center side communicate with the residual pressure loss regeneration ports 32a and 32b, thereby increasing the pressure in the cylinder bore 25a.

  Further, thereafter, the self-pressure restrictor 52 and the cylinder bore 25a communicate with each other, whereby the pressure in the cylinder bore 25a is further increased and becomes substantially the same pressure as the valve plate discharge port PB2. That is, the pressure in the cylinder bore 25a smoothly transitions from the flat pressure of the valve plate suction port PB1 to the high pressure of the valve plate discharge port PB2 by the two-step pressure increase by the residual pressure regeneration circuit 20 and the self-pressure restrictor 52, It is possible to reduce erosion and noise due to cavitation due to abrupt changes and increase efficiency. The flat pressure of the valve plate suction port PB1 is a state where the pressure is almost zero.

(Transition from the discharge process to the suction process)
Next, the operation during the transition from the discharge process to the suction process will be described. FIG. 6 is a diagram showing a positional relationship between the valve plate 7 and the cylinder bore 25f in the vicinity of the top dead center side. FIG. 7 is a cross-sectional view showing a state in the cylinder bore showing a state in which the swash plate angle D1 is maximized. Further, FIG. 8 is a cross-sectional view showing a state in the cylinder bore showing a state in which the swash plate angle D1 is minimized.

  As shown in FIG. 6, when the rotation center line Af of the cylinder bore 25f is at an angle −θ5 with respect to the top dead center θ0, the cylinder bore 25f is released from the communication state with the valve plate discharge port PB2. At this time, the cylinder bore 25f is in a high residual pressure state, and the cylinder bore 25f is compressed to the top dead center. When the rotation center line Af is an angle −θ5, the angle at the front end of the cylinder bore 25f in the traveling direction is θ1.

  The residual pressure loss ports 33af, 33bf and the residual pressure loss recovery ports 31a, 31b begin to communicate with each other when the angle of the front end of the cylinder bore 25f is θ1. The residual pressure loss ports 33af, 33bf and the residual pressure loss recovery ports 31a, 31b communicate with each other so that the residual pressure in the cylinder bore 25f moves to the communication hole 30a and accumulates, and then is used for boosting the cylinder bore 25a on the bottom dead center side. It is done.

  Thereafter, when the angle at the front end of the cylinder bore 25f reaches θ2, the cylinder bore 25f starts to communicate with the residual pressure release holes 61a and 61b. The residual pressure in the cylinder bore 25f can be further reduced by the communication between the cylinder bore 25f and the residual pressure release holes 61a and 61b. Here, as described above, the opening of the residual pressure release holes 61a and 61b is controlled by the flow control valve V10 according to the swash plate angle and the rotation speed. That is, when the swash plate angle is large, as shown in FIG. 7, since the residual pressure oil amount L is small, it does not take time to extract the residual pressure, so the flow control valve V10 is in the throttle state. Even when the rotational speed is low, it takes no time to extract the residual pressure, so that the flow control valve V10 is in the throttle state. On the other hand, when the swash plate angle is small, as shown in FIG. 8, since the residual pressure oil amount L is large, it takes time to extract the residual pressure, so the flow control valve V10 is opened and fully opened. Even when the rotational speed is high, it takes time to extract the residual pressure, so that the flow control valve V10 is fully opened. The flow rate control valve V10 continuously changes in an analog manner from the fully closed state to the fully open state in accordance with the control signal S10.

  Thereafter, when the angle at the tip of the cylinder bore 25f in the traveling direction reaches θ3, the cylinder bore 25f starts to communicate with the timing adjustment hole 71. When the cylinder bore 25f and the timing adjustment hole 71 communicate with each other, the opening of the timing adjustment hole 71 that communicates with the flow rate control valve V11 is controlled. As shown in FIG. 7, when the swash plate angle is large, the flow rate control valve V11 does not take time to extract the residual pressure because the residual pressure oil amount L is small. For this reason, when the cylinder bore 25f and the timing adjustment hole 71 are communicated with each other, the residual pressure is a flat pressure, and since it is a suction process, suction into the cylinder bore 25f is performed. Therefore, the flow control valve V11 is fully opened so that the opening of the timing adjustment hole 71 becomes large, contrary to the flow control valve V10. Even when the rotational speed is low, it takes no time to extract the residual pressure, so that the flow control valve V11 is fully opened. On the other hand, when the swash plate angle is small, since the residual pressure oil amount L is large as shown in FIG. 8, it takes time to extract the residual pressure. For this reason, when the cylinder bore 25f and the timing adjustment hole 71 communicate with each other, a little residual pressure remains. Therefore, contrary to the flow control valve V10, the flow control valve V11 is in a throttle state in order to reduce the opening of the timing adjustment hole 71. Even when the rotational speed is low, it takes no time to extract the residual pressure, so that the flow control valve V11 is in the throttle state. The flow control valve V11 continuously changes in an analog manner from the fully closed state to the fully open state in accordance with the control signal S11.

  In this embodiment, at the time of transition from the discharge process to the suction process, the residual pressure in the cylinder bore 25f is reduced in two stages by the residual pressure regeneration circuit 30 and the residual pressure release holes 61a and 61b, and the swash plate angle and rotational speed are reduced. Accordingly, the flow control valve V10 controls the opening of the residual pressure relief holes 61a and 61b. As a result, regardless of changes in the swash plate angle and rotational speed, the residual pressure in the cylinder bore 25f is smoothly reduced until it communicates with the valve plate suction port PB1 during the transition from the discharge process to the suction process, and the cylinder bore 25f Can be prevented from aeration when communicating with the valve plate suction port PB1. This also reduces erosion and noise caused by aeration and increases efficiency.

  Further, when the cylinder bore 25f and the residual pressure release holes 61a and 61b communicate with each other, the residual pressure may already be low by the residual pressure regeneration circuit 30. In particular, when the swash plate angle is maximum or when the rotational speed is low, the residual pressure is low, and hydraulic oil may flow backward from the tank. However, in this case, the flow rate control valve V10 is configured to throttle the oil passage, so that backflow of hydraulic oil from the tank can be prevented.

  Moreover, the suction area of the valve plate suction port PB1 can be made substantially variable by the timing adjustment hole 71 and the flow control valve V11, and the suction process can be performed efficiently.

(Modification 1)
FIG. 9 is a view showing a configuration in the vicinity of the top dead center of the first modification of the hydraulic pump according to the embodiment of the present invention. As shown in FIG. 9, in the first modification, a flow control valve V12 is provided in the middle of the communication hole 30a of the residual pressure regeneration circuit 30 and in the vicinity of the residual pressure loss recovery ports 31a and 31b.

  Like the flow rate control valve V10, the flow rate control valve V12 has a small residual pressure oil amount L, as shown in FIG. 7, when the swash plate angle is large. Set to the aperture state. Even when the rotational speed is low, it takes no time to extract the residual pressure, so that the flow control valve V12 is in the throttle state. On the other hand, when the swash plate angle is small, as shown in FIG. 8, since the residual pressure oil amount L is large, it takes time to extract the residual pressure, so that the flow control valve V12 is fully opened. Even when the rotational speed is high, it takes time to extract the residual pressure, so that the flow control valve V12 is fully opened. The flow control valve V12 continuously changes in an analog manner from the fully closed state to the fully open state in accordance with the control signal S12.

  In the first modification, a change in the residual pressure at the time of recovery of the residual pressure loss to the residual pressure regeneration circuit 30 is made independent of the swash plate angle and the rotational speed, so that a constant residual pressure is always transmitted to the communication hole 30a. Accordingly, the residual pressure in the cylinder bore 25f is always constant. As a result, when the cylinder bore 25f communicates with the valve plate suction port PB1, erosion and noise caused by aeration can be stably reduced and efficiency can be increased.

(Modification 2)
FIG. 10 is a diagram showing a configuration in the vicinity of the top dead center of Modification 2 of the hydraulic pump according to the embodiment of the present invention. As shown in FIG. 10, in the second modification, the control signals S10, S11, S12 input to the flow control valves V10, V11, V12 in the first modification are set as one control signal S20. This simplifies the configuration of the flow rate control valve system. In the case of this one control signal S20, the operation of the flow control valve V11 is opposite to the operation of the flow control valves V10 and V12. For example, when the value of the control signal S20 increases, the flow control valves V10 and V12 shift in the order of the fully closed state, the throttle state, and the fully open state, but the flow control valve V11 is in the fully open state, the throttle state, and the fully closed state. Move in the order of.

(Modification 3)
FIG. 11 is a diagram showing a configuration in the vicinity of the top dead center of the third modification of the hydraulic pump according to the embodiment of the present invention. As shown in FIG. 11, in the third modification, residual pressure loss recovery ports 131a and 131b in which the positions of the residual pressure loss recovery ports 31a and 31b in the first and second modifications are shifted in the circumferential direction are used. That is, after the residual pressure loss recovery port 131a communicates with the residual pressure loss port 33a, the residual pressure loss recovery port 131b communicates with the residual pressure loss port 33b. Further, residual pressure release holes 161a and 161b are formed by shifting the positions of the residual pressure release holes 61a and 61b in the first and second modifications in the circumferential direction. That is, after the residual pressure loss recovery port 131b and the residual pressure loss port 33b communicate with each other, the residual pressure release hole 161a communicates with the cylinder bore 25f, and after this communication, the residual pressure release hole 161b communicates with the cylinder bore 25f. The cylinder bore 25f communicates with the suction timing adjustment hole 71 after the residual pressure release hole 161b communicates with the cylinder bore 25f.

  The residual pressure loss recovery ports 131a and 131b and the residual pressure release holes 161a and 161b are associated with the openings of the residual pressure loss recovery ports 131a and 131b and the residual pressure release holes 161a and 161b by the swash plate 7. When the pump rotates at a high speed in a narrow confinement area, the timing of opening can be varied for the case where it is not sufficient to vary the area, so that the residual pressure loss recovery ports 31a and 31b and the remaining pressure can be changed. It is made smaller than the pressure release holes 61a and 61b.

  Further, instead of the flow control valve V10, two flow control valves V10a and V10b are provided. The flow control valve V10a controls the opening of the residual pressure release hole 161a via the communication hole 62a. The flow control valve V10b controls the opening of the residual pressure release hole 161b through the communication hole 62b. The flow control valve V12 controls only the opening of the residual pressure loss recovery port 131b via the communication hole 30bb. The residual pressure loss recovery port 131a is not connected to the flow rate control valve but is directly connected to the communication holes 30aa and 30a.

  In Modification 3, since the two-stage pressure reduction of the residual pressure in the cylinder bore 25f is a four-stage pressure reduction, a smoother pressure reduction is possible.

(Modification 4)
FIG. 12 is a view showing a configuration in the vicinity of the top dead center of the modified example 4 of the hydraulic pump according to the embodiment of the present invention. As shown in FIG. 12, in the fourth modification, the residual pressure loss ports 33a and 33b in the first and second modifications are located at the positions of the residual pressure loss ports 133af provided by cutting out the outer peripheral side wall and the outer peripheral side wall of the cylinder bore 25f. , 133bf. Further, residual pressure loss recovery ports 231a and 231b are formed by shifting the positions of the residual pressure loss recovery ports 31a and 31b in the circumferential direction in accordance with the position change of the residual pressure loss ports 133a and 133b.

  In this modified example 4, since the residual pressure loss ports 133af and 133bf are provided on the side wall of the cylinder bore 25f, after the cylinder bore 25f is disconnected from the valve plate discharge port PB2, until it communicates with the valve plate suction port PB1. Further, it is possible to ensure a wide circumferential region on the front end side in the traveling direction of the cylinder bore 25f. As a result, the fixed opening of the residual pressure release holes 61a and 61b and the timing adjustment hole 71 can be increased, so that the flow rate adjustment by the flow rate control valves V10 and V11 can be further increased, and fine pressure reduction processing can be performed. It becomes possible.

(Modification 5)
FIG. 13 is a cross-sectional view taken along line BB of Modification 5 of the hydraulic pump illustrated in FIG. FIG. 14 is a diagram illustrating a configuration in which the sliding surface with the valve plate in the cylinder block of the fifth modification is viewed in the −X direction. Further, FIG. 15 is an explanatory diagram for explaining the operation at the time of transition from the suction process to the discharge process in Modification 5.

  In this modified example 5, as shown in FIG. 13 and FIG. 14, the cylinder block 6 is provided with an elongated hole cutout provided on the outside of the inner peripheral side wall of each cylinder bore 25 in the same manner as the residual pressure loss port 133bf. A groove 43 is provided. In addition, each cylinder bore 25 is provided with only a residual pressure loss port 33a on the outer peripheral side, and is not provided with a residual pressure loss port 33b. This is because the provision of the residual pressure loss port 33b overlaps the elongated hole cutout groove 43 on the same circumference.

  On the other hand, the valve plate 7 has a cylinder bore 25 communicating with the valve plate discharge port PB2 in the vicinity of the bottom dead center corresponding to the same circumference as the port of the long hole notch groove 43 and on the circumference of the discharge process side. An elongated hole port 42 is provided at a position where it communicates before entering the state. The long hole port 42 communicates with the valve plate discharge port PB2 through a long hole realized by a long communication hole, and forms a long hole circuit 40. Other configurations are the same as those of the embodiment shown in FIGS.

  This long hole is provided in the valve plate 7 and the end cap 8, and the length thereof is set to about 1/4 to 1/2 of the generated pulsation wavelength. The long hole is provided as the long hole circuit 40 by increasing the internal pressure of the cylinder bore 25 by the pressure on the cylinder bore 25 side of the long hole circuit 40, and the pressure reduction of the long hole circuit 40 after this pressure increase is caused to the valve plate discharge port PB2 side. This is because it is transmitted late. On the contrary, it can be said that the elongated hole delays and buffers the pressure propagation on the valve plate discharge port PB2 side, thereby reducing the pressure fluctuation of the valve plate discharge port PB2. Further, the long hole has such a length that the internal pressure on the cylinder bore 25 side can be restored to the pressure on the valve plate discharge port PB2 side before communication with the cylinder bore 25 that communicates next when not communicating.

  Specifically, when the rotational speed of the cylinder block 6 is 2000 rpm, the number of cylinder bores 25 is 9, and the propagation speed of the pulsating wave is 1000 m / s, the wavelength of the pulsating wave is about 3 m. Therefore, if the long hole is ½ wavelength long, the length of the long hole circuit 40 is about 1.5 m. However, when the length is longer than one wavelength, the pressure replenishment to the long hole circuit 40 by the valve plate discharge port PB2 side is delayed after the pressure propagation to the long hole port 42 side, and the pressure replenishment to the next cylinder bore 25 is delayed. Will not be enough.

  The elongated hole circuit 40 further increases the pressure in the cylinder bore 25 that shifts from the suction process to the discharge process. The reason why the length of the long hole circuit 40 is about 1/4 to 1/2 of the pulsation wavelength is widened because the pulsation waveform varies depending on the hydraulic circuit. For example, when the pulsation waveform is an ideal sine wave, the time (length) from the lowest pressure to the highest pressure is ½ wavelength, but the actual pulsation waveform of a hydraulic pump has a small amplitude fluctuation. This is because the time (length) from the lowest pressure to the highest pressure is usually about ¼ wavelength while including noise. Each communication hole is about 6 mmφ.

  Here, referring to FIG. 15, the pressure increase in the cylinder bore 25 that shifts from the suction process to the discharge process is performed by first communicating the residual pressure loss port 33aa of the cylinder bore 25a with the residual pressure loss regeneration port 32a. The circuit 30 boosts the pressure in the cylinder bore 25a.

  Thereafter, the long hole cutout groove 43a of the cylinder bore 25a communicates with the long hole port 42, and the pressure in the cylinder bore 25a is further increased by the high pressure of the valve plate discharge port PB2 via the long hole circuit 40.

  Thereafter, the self-pressure restrictor 52 and the cylinder bore 25a communicate with each other, the pressure in the cylinder bore 25a is further increased, and the pressure is almost the same as the pressure in the valve plate discharge port PB2, and the discharge process is performed smoothly.

  That is, in the fifth modified example, when the long hole circuit 40 is further provided and the process proceeds from the suction process to the discharge process, the pressure in the cylinder bore 25 is changed in the order of the residual pressure regeneration circuit 30, the long hole circuit 40, and the self-pressure restriction 52. Thus, the pressure is increased in three stages, so that noise due to erosion and pulsation in the cylinder bore due to cavitation when shifting from the suction process to the discharge process is suppressed, and the efficiency is further increased.

  In the above-described embodiment and modification, the self-pressure throttle 52 communicated by the oblique communication hole 53 is used, but a notch that is a notch groove may be used instead.

  Further, in this embodiment and the modification, the radial width of the valve plate suction port PB1 and the radial width of the cylinder port 25 are set to be substantially the same, and the radial width of the valve plate discharge port PB2 is set as follows. The cylinder port 25 is set to be narrower than the radial width. As a result, the hydraulic pressure balance between suction and discharge can be maintained.

  Furthermore, in the above-described embodiments and modifications, the hydraulic pump has been described as an example. However, the present invention is not limited to this and can be applied to a hydraulic motor. In the case of a hydraulic motor, the high pressure side corresponds to the discharge side of the hydraulic pump, and the low pressure side corresponds to the suction side of the hydraulic pump.

  In the above-described embodiments and modifications, an example of a swash plate type hydraulic pump / motor has been described. However, the present invention is not limited to this, and a swash plate type hydraulic pump / motor is also applicable. In the case of motor driving, the rotation of the cylinder block 6 is reversed, and residual pressure loss recovery ports 31a and 31b, residual pressure loss regeneration ports 32a and 32b provided in the swash plate 7, residual pressure release holes 61a and 61b, timing The adjustment hole 71, the self-pressure restrictor 52, the long hole port 42, and the like are arranged symmetrically with respect to a line that passes through the rotation axis and is orthogonal to a straight line connecting the top dead center and the bottom dead center. On the other hand, the residual pressure loss ports 33, 33a to 33i provided in the cylinder block 6 are provided on the rotational direction side of each cylinder bore.

DESCRIPTION OF SYMBOLS 1 Shaft 2 Case 3 Swash plate 4 Shoe 5,10 Piston 6 Cylinder block 7 Valve plate 8 End cap 9a, 9b Bearing 11 Spline structure 14 Ring 15 Spring 16 Movable ring 17 Needle 18 Press member 20, 21 Bearings 25, 25a-25i Cylinder bore 30 Residual pressure regeneration circuit 30a, 34a, 34b, 53, 62, 63, 72, 73 Communication hole 31a, 31b, 131a, 131b, 231a, 231b Residual pressure loss recovery port 32a, 32b Residual pressure loss regeneration port 33, 33a ˜33i, 131af, 133bf Residual pressure loss port 40 Elongated hole circuit 42 Elongated hole port 43 Elongated hole notch groove 52 Self-pressure restriction 60 Residual pressure relief circuit 61a, 61b, 161a, 161b Residual pressure relief hole 64 Tank 70 Timing adjustment circuit 71 Timing Adjustment hole 100 Speed sensor P1 Suction port P2 Discharge port PB1 Valve plate suction port PB2 Valve plate discharge port S, Sa Sliding surface S10, S10a, S10b, S11, S12, S12b, S20 Control signals V10, V11, V12, V10a, V10b Flow control valve C10 Controller D1 Swash plate angle D2 Rotational speed

Claims (6)

A cylinder block in which a plurality of cylinder bores are formed around the rotation shaft slides against a valve plate having a high-pressure side port and a low-pressure side port, and the amount of reciprocation of the piston in each cylinder bore by the inclination of the swash plate An axial type hydraulic pump / motor that controls
The residual pressure in the top dead center side cylinder bore is communicated with the low pressure side port after the top dead center side cylinder bore is disconnected from the communication state with the high pressure side port until it communicates with the low pressure side port. A residual pressure regeneration circuit that transmits to the bottom dead center cylinder bore out of the state;
A residual pressure release hole communicating with the top dead center side cylinder bore is provided after the top dead center side cylinder bore communicates with the residual pressure regeneration circuit to reduce the residual pressure until the top dead center side cylinder bore communicates with the low pressure side port. A residual pressure release circuit having a flow rate control valve that adjusts the flow rate of hydraulic oil drawn from the residual pressure release hole to the tank side according to the swash plate angle and the rotation speed;
A hydraulic pump / motor characterized by comprising:   The top dead center side cylinder bore and the low pressure side port communicate with each other after the residual pressure in the top dead center side cylinder bore is reduced through the residual pressure release hole and before the communication with the low pressure side port. A timing adjustment hole is provided, and a timing adjustment flow control valve is provided for adjusting the flow rate of hydraulic fluid moving from the high pressure side port into the top dead center side cylinder bore through the timing adjustment hole according to the swash plate angle and rotation speed. The hydraulic pump / motor according to claim 1, further comprising a timing adjusting circuit.   The residual pressure regeneration circuit includes a residual pressure flow control valve that adjusts a flow rate of hydraulic oil discharged from the top dead center cylinder bore according to a swash plate angle and a rotational speed. 2. The hydraulic pump / motor according to 2.   The hydraulic pump / motor according to claim 3, wherein the flow control valve, the timing adjustment flow control valve, and the residual pressure flow control valve are controlled by the same control signal.   A plurality of the top dead center side port and the bottom dead center side port and / or the residual pressure release hole of the residual pressure regeneration circuit are provided, and are formed to be shifted along the traveling direction of the cylinder bore. The hydraulic pump / motor according to claim 1. A self-pressure throttle that connects the cylinder bore and the high-pressure side port immediately before each cylinder bore communicates with the high-pressure side port of the valve plate;
After the bottom dead center cylinder bore is disconnected from the low pressure port, the bottom dead center is connected between the high pressure port and the bottom dead center cylinder bore until the cylinder bore communicates with the self-pressure throttle. An elongated hole that is temporarily communicated via a notch groove provided on the side cylinder bore side is provided, and the elongated hole transmits the high pressure in the elongated hole on the cylinder bore side to the cylinder bore when communicating, and the cylinder bore when not communicating A long hole circuit having a length capable of restoring the internal pressure of the long hole on the side to the pressure on the high pressure side port before communication with the next cylinder bore;
The hydraulic pump / motor according to claim 1, wherein the hydraulic pump / motor is provided.

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