JP3585346B2 - Piston pump / motor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a piston pump motor.
[0002]
[Prior art]
A conventional piston pump / motor includes a plurality of cylinders arranged in a cylinder block in parallel with a rotation axis thereof, and a plurality of pistons each defining a volume chamber in each cylinder. One end of the piston protrudes from the cylinder and is supported by a shoe that always contacts the swash plate. When the cylinder block rotates, each piston reciprocates between the swash plate and expands and contracts the volume chamber of the cylinder.
[0003]
A valve plate for controlling the discharge and suction of the cylinder is provided, and the inflow port and the outflow port are opened on the same circumference around the rotation axis of the cylinder block. A kidney port is formed in each cylinder toward the valve plate, and a volume chamber of the cylinder is selectively communicated with an inflow port or an outflow port of the valve plate according to the rotation angle of the cylinder block.
[0004]
For each rotation of the cylinder block, each piston makes one reciprocation of the cylinder. In the process of expanding the volume chamber of the cylinder, fluid is sucked into the volume chamber from the inlet port of the valve plate, and the fluid is discharged to the outlet port of the valve plate in the process of compressing the volume chamber of the cylinder.
[0005]
Each volume chamber repeats the process of “suction” and “discharge”, and the pressure fluctuation accompanying the switching of these processes has a specific frequency component represented by the following equation.
[0006]
fn = n · Z · N / 60 [Hz]
(Z: number of pistons, N: rotation speed, n = 1, 2, 3, ...; order)
This pressure fluctuation causes vibration and noise of the pump / motor, and is transmitted from the piping to the actuator and the like, and may cause noise and vibration throughout the apparatus. Further, when the specific frequency component and the resonance frequency of the pipe or the structure coincide with each other, there is a possibility that the generation level of noise and vibration is increased.
[0007]
Therefore, in the axial piston pump, the cylinder 20 and the kidney port 21 of the cylinder block 22 are arranged at irregular intervals in the circumferential direction as shown in FIG. 5 so as to disperse the frequency component of the pressure fluctuation and prevent the level of the specific frequency component from increasing. (Unequal pitch) and those in which only the kidney ports 21 are arranged at irregular intervals (unequal pitch) in the circumferential direction in the range of the cross-sectional shape of the cylinder 20 as shown in FIG. (Japanese Utility Model Laid-Open No. 7-310646, Japanese Patent Publication No. 48-19121).
[0008]
[Problems to be solved by the invention]
In the conventional example shown in FIG. 5, the cylinders 20 including the kidney ports 21 are arranged at irregular pitches on the same circumference. It is difficult to make pitch equal. In addition, since a portion where the thickness between the adjacent cylinders 20 and between the kidney ports 21 becomes thin occurs, there is a disadvantage that the strength of the cylinder block is disadvantageously secured. In the conventional example of FIG. 6, only the arrangement of the kidney ports 21 is made unequal pitch, but also in this case, since the arrangement of the kidney ports 21 is on the same circumference, the range of uneven pitch is limited by the number of cylinders 20. There was a defect that.
[0009]
An object of the present invention is to solve such a problem.
[0010]
[Means for Solving the Problems]
According to the first aspect, a cylinder disposed in a cylinder block in parallel with a rotation axis thereof, a plurality of pistons defining a volume chamber in each cylinder, and a volume chamber of each cylinder being expanded and contracted as the cylinder block rotates. A swash plate that reciprocates the piston, a valve plate that has an inflow port and an outflow port formed on the same circumference around the rotation axis of the cylinder block, and the rotation angle of the cylinder block to each volume chamber of each cylinder. A plurality of kidney ports selectively communicating with the inflow port and the outflow port of the valve plate according to the angle of each kidney port on the same circumference centered on the rotation axis of the cylinder block in the piston pump / motor. At each angular position, the cylinder block is turned so that the kidney port is shifted radially to the relative position with the adjacent kidney port at each angular position. By arranging the shaft in one of the plurality of concentric circles of different radius around the, and wherein the set to unequal pitch intervals Kidonipoto the circumferential direction.
[0011]
In the second invention, cylinders arranged in a cylinder block in parallel with the rotation axis thereof, a plurality of pistons each defining a volume chamber in each cylinder, and expansion and contraction of the volume chamber of each cylinder as the cylinder block rotates. A swash plate that reciprocates the piston, a valve plate that has an inflow port and an outflow port formed on the same circumference around the rotation axis of the cylinder block, and the rotation angle of the cylinder block to each volume chamber of each cylinder. A plurality of kidney ports selectively communicating with the inflow port and the outflow port of the valve plate according to the angle of each cylinder on the same circumference around the rotation axis of the cylinder block in the piston pump / motor. The cylinder is centered on the rotation axis of the cylinder block at each angular position to give the cylinder a relative position with the adjacent cylinder in the radial direction. By placing one on a plurality of concentric circles of different radius which is characterized in that it is set to unequal pitch intervals Kidonipoto the circumferential direction.
[0012]
【The invention's effect】
In the first invention, by changing the arrangement of the kidney port in the radial direction, the intersection angle between the straight lines connecting the front and rear ends in the rotation direction of the kidney port with the rotation center of the cylinder block, respectively, is defined as a kidney port located on a circle having a small radius. As compared with, the kidney port located on the circumference with the larger radius is smaller. Therefore, to increase the distance between adjacent kidney ports, the kidney port should be arranged on a circle with a large radius, and to reduce the distance, the kidney port should be arranged on a circle with a small radius. In addition, since each of the kidney ports passes on a circumference having a different radius with respect to the inflow port and the outflow port of the valve plate, the timing of opening and closing each of them varies. As a result, even when the cylinders are arranged at equal intervals on the same circumference, irregularities occur in the timing of switching between “suction” and “discharge” of each volume chamber, thereby reducing noise of the pump / motor. Can be obtained.
[0013]
According to the second aspect of the present invention, by changing the positions of the cylinders and the kidney ports in the radial direction, the linear distance between the adjacent cylinders and the kidney ports increases, so that the kidney ports can be formed at a large uneven pitch in the circumferential direction. . The stroke of the piston changes between the cylinder block and the swash plate according to the radius of the cylinder position. That is, the stroke of a piston reciprocating on a cylinder on a circle with a small radius becomes small, and the stroke of a piston reciprocating on a cylinder on a circle with a large radius becomes large. Therefore, since the flow rate differs for each cylinder, the piston thrust itself does not have periodicity. As a result, the irregularities of the flow rate fluctuation and the pressure fluctuation accompanying the switching between “suction” and “discharge” of each volume chamber increase, so that noise reduction of the pump / motor can be effectively realized. Further, by shifting the cylinder and the kidney port in the radial direction, the thickness between the adjacent cylinders and between the kidney ports can be increased, so that the strength of the cylinder block can be secured well.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In FIG. 1, a cylinder block 3 and a swash plate 4 are housed in an internal space formed by a casing 1 and a port block 2. Reference numeral 5 denotes a rotating shaft (shaft) that penetrates the center of the cylinder block 3, and one end of the rotating shaft projects out of the casing 1. The rotating shaft 5 is rotatably supported by the shaft hole 2a of the port block 2 and the bearing 1a of the casing 1, and rotates the cylinder block 3 integrally.
[0015]
A plurality of cylinders 6 are arranged in the cylinder block 3 in the circumferential direction in parallel with the rotation shaft 5, and a piston 8 defining a volume chamber 7 is inserted into each cylinder 6. One end of each piston 8 protrudes from the cylinder block 3 and is supported by a shoe 9 which always contacts the swash plate 4. When the cylinder block 3 rotates, each piston 8 reciprocates with the swash plate 4 to expand and contract the volume chamber 7 of the cylinder 6.
[0016]
The swash plate 4 is attached to the casing 1 via a support shaft 10 so as to be tiltable. A valve plate 11 for controlling “discharge” and “suction” of each volume chamber 7 is provided, and an inflow port (12a in FIG. 3) and an outflow port which open on the same circumference around the rotation shaft 5 of the cylinder block 3. A port (12b in FIG. 3) is provided. An inlet passage and an outlet passage communicating with these ports 12a and 12b, respectively, are provided in the port block 2. A kidney port 13 is formed in each cylinder 6 toward the valve plate 11, and selectively communicates each volume chamber 7 with the inflow port 12 a or the outflow port 12 b of the valve plate 11 according to the rotation angle of the cylinder block 3.
[0017]
Each rotation of the cylinder block 3 causes each piston 8 to make one reciprocation of the cylinder 6. In the process of expanding the volume chamber 7 of the cylinder 6, fluid is sucked from the inflow port 12 a of the valve plate 11 into the volume chamber 7, and in the process of compressing the volume chamber 7 of the cylinder 6, the fluid flows out of the valve plate 11. It discharges to the port 12b.
[0018]
FIG. 2 shows an arrangement state of the cylinder 6 and the kidney port 13. The cylinders 6 are arranged at equal intervals on the same circumference around the rotation shaft 5. With respect to the kidney port 13, angular positions are determined at equal intervals on the same circumference around the rotary shaft 5, and the radius around the rotary shaft 5 is r1 so that the angular position falls within the range of the cross-sectional shape of the cylinder 6 at that angular position. Ｒr3 and a plurality of concentric circles different from r3.
[0019]
The vibration and noise of the piston pump / motor may be caused by pressure fluctuations and flow fluctuations caused by switching between “suction” and “discharge” of each volume chamber 7, and the sum of the flow rates discharged from each cylinder 6 may fluctuate at a constant cycle. This is a main cause of occurrence, and the basic cycle of noise and vibration is determined by the switching timing (cycle) and the discharge flow rate fluctuation.
[0020]
By changing the arrangement of the kidney port 13 in the radial direction, the intersection angle between the straight lines connecting the front and rear ends of the kidney port 13 in the rotation direction to the center of the rotation shaft 5 is different from the radius of the kidney port located on the circumference of the radius r1 by the radius. The kidney port 13 located on the circumference of r2 is large, and the kidney port 13 located on the circumference of the radius r3 is small.
[0021]
In order to increase the interval between the adjacent kidney ports 13, the kidney port 13 may be arranged on the circumference of the radius r3, and in order to reduce the interval, the kidney port 13 may be arranged on the circumference of the radius r2. Also, as shown in FIG. 3, since each of the kidney ports 13 passes through one of the circles of the radii r1 to r3 with respect to the inflow port 12a and the outflow port 12b of the valve plate 11, the opening / closing timing changes.
[0022]
As a result, even if the cylinders 6 are arranged at equal intervals on the same circumference, irregularities occur in the switching cycle of “suction” and “discharge” due to the reciprocation of the piston 8, so that the fundamental component of the rotation cycle Vibration energy is less likely to concentrate on the piston pump and the noise of the piston pump / motor can be reduced.
[0023]
FIG. 4 shows an arrangement state of cylinders 6 as another embodiment. Each cylinder 6 determines angular positions at unequal intervals on the same circumference centered on the rotating shaft 5, and at each angular position. They are selectively arranged on the circumference of the radii r1 to r3. That is, the relative position of the cylinder 6 changes in the circumferential direction and the radial direction. Although not shown, each of the kidney ports 13 is arranged so as to correspond to the relative position of these cylinders 6 and is formed so as to fall within the range of the cross-sectional shape of each cylinder 6.
[0024]
By shifting the relative position of the cylinder 6 in the radial direction, the kidney port 13 can have a large uneven pitch in the circumferential direction. For this reason, the irregularity of the switching timing of “suction” and “discharge” of each volume chamber 7 increases.
[0025]
The stroke of the piston 8 changes between the cylinder block 3 and the swash plate 11 according to the radius of the cylinder position. In other words, the stroke of the piston 8 reciprocating on the cylinder 6 on the circle with a small radius becomes small, and the stroke of the piston 8 reciprocating on the cylinder 6 on the circle with a large radius becomes large.
[0026]
For this reason, the flow rate differs for each cylinder 6, and the piston thrust itself does not have periodicity, so that the noise reduction of the pump / motor can be further promoted. In addition, by displacing the cylinder 6 in the circumferential direction and the radial direction, the thickness between the adjacent cylinders 6 and between the kidney ports 13 is increased, so that the strength of the cylinder block 3 can be secured well.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a piston pump / motor representing an embodiment of the present invention.
FIG. 2 is an arrangement state diagram of a kidney port.
FIG. 3 is a front view of the valve plate.
FIG. 4 is a diagram showing the arrangement of cylinders.
FIG. 5 is an explanatory diagram of a conventional example.
FIG. 6 is an explanatory diagram of a conventional example.
[Explanation of symbols]
3 Cylinder block 4 Swash plate 5 Rotating shaft 6 Cylinder 7 Volume chamber 8 Piston 11 Valve plate 12a Inflow port 12b Outflow port 13 Kidney port

Claims (2)

Cylinders arranged in a cylinder block in parallel with the axis of rotation, multiple pistons each defining a volume chamber in each cylinder, and reciprocating pistons to expand and contract the volume chambers in each cylinder as the cylinder block rotates A swash plate, a valve plate in which an inflow port and an outflow port are formed on the same circumference around the rotation axis of the cylinder block, and the volume chamber of each cylinder is formed by a valve plate according to the rotation angle of the cylinder block. In the piston pump / motor, a plurality of kidney ports selectively communicating with the inflow port and the outlet port are determined, and the angular position of each kidney port is determined on the same circumference around the rotation axis of the cylinder block. The kidney port is centered on the rotation axis of the cylinder block to give a radial displacement to the relative position of the kidney port with the adjacent kidney port. By placing different one of the plurality of concentric circles of diameter, piston pump motor, characterized in that set in the irregular pitch intervals Kidonipoto the circumferential direction. Cylinders arranged in a cylinder block in parallel with the axis of rotation, multiple pistons each defining a volume chamber in each cylinder, and reciprocating pistons to expand and contract the volume chambers in each cylinder as the cylinder block rotates A swash plate, a valve plate in which an inflow port and an outflow port are formed on the same circumference around the rotation axis of the cylinder block, and the volume chamber of each cylinder is formed by a valve plate according to the rotation angle of the cylinder block. In the piston pump / motor, a plurality of kidney ports selectively communicating with the inflow port and the outflow port are provided, and the angular position of each cylinder is determined on the same circumference around the rotation axis of the cylinder block. In order to give a radial displacement to the relative position between the cylinder and the adjacent cylinder, the cylinder with different radius around the rotation axis of the cylinder block By placing one on a plurality of concentric circles, piston pump motor, characterized in that set in the irregular pitch intervals Kidonipoto the circumferential direction.

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