JPH08284805A - Axial piston type hydraulic rotary machine - Google Patents

Abstract

PURPOSE: To reduce pulsation by restraining pressure fluctuation generated between a high pressure side port and cylinders when cylinders are each communicated with the high pressure side port. CONSTITUTION: A cylinder port 7A is communicated with a pressure accumulating chamber 18 through a first oil passage 20 after communication of it with an intake port 14 is interrupted, and it is communicated with the pressure accumulating chamber 18 through a second oil passage 23 after it is communicated with a discharge port 15. Since pressure oil in the pressure accumulating chamber 18 is introduced into cylinders through the first oil passage 20, pressure fluctuation to be generated between the cylinders and the discharge port 15 can be decreased. The fluctuation width of the pump discharge flow rate can be made small by performing the replenishment of pressure oil to the pressure accumulating chamber 18 through the second oil passage 23 is performed in the period in which the pump discharge flow rate is increased to the approximately maximum extent, and pulsation can be effectively restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial piston type hydraulic rotary machine suitable for use as a hydraulic pump as a hydraulic source of hydraulic equipment, a hydraulic motor as a drive source, and the like.

[0002]

2. Description of the Related Art Generally, swash plate type and swash axis type axial piston type hydraulic rotating machines are known as hydraulic pumps used as hydraulic sources for hydraulic equipment mounted on construction machines and hydraulic motors used as drive sources. Has been.

As an axial piston type hydraulic rotary machine of this type, for example, a hydraulic pump is provided with a casing, a rotary shaft rotatably provided in the casing, and a rotary shaft located inside the casing and integrally with the rotary shaft. A cylinder block that is provided so as to rotate and has a plurality of cylinders that are spaced apart in the circumferential direction and extend in the axial direction, and a cylinder block that is slidably fitted in each cylinder of the cylinder block and that rotates As a low pressure side port that is provided between a plurality of pistons that suck and discharge hydraulic oil by displacing in the axial direction with the above, and the cylinder and the end surface of the cylinder block and that communicates intermittently with each cylinder. And a valve plate having a discharge port as a high-pressure side port.

In the hydraulic pump constructed as described above, when the rotary shaft is rotationally driven by a drive source such as an engine, the cylinder block rotates together with the rotary shaft in the casing. As a result, the piston reciprocates in each cylinder of the cylinder block, and the working oil sucked into the cylinder from the suction port is pressurized by the piston and discharged to the discharge port as pressure oil.

The operation of the cylinder block, the piston and the valve plate will now be described. When the cylinder port of each cylinder communicates with the suction port of the valve plate, the direction in which the piston projects from the beginning to the end of the suction port The suction stroke is such that the working oil is sucked into the cylinder through the suction port. On the other hand, when the cylinder port of each cylinder communicates with the discharge port, the piston is displaced in the direction in which the piston enters the cylinder from the start end to the end of the discharge port to pressurize the hydraulic oil in the cylinder to enter the discharge port. This is the discharging stroke for discharging. Then, as the cylinder block rotates so as to repeat this operation (stroke), the working oil sucked into the cylinder from the suction port in the suction stroke is pressurized in the discharge stroke and discharged to the discharge port. It is designed to supply hydraulic equipment such as cylinders.

By the way, in the above-described conventional hydraulic pump, the cylinder port of each cylinder communicates with the discharge port because the inside of the cylinder that has sucked the working oil through the suction port of the valve plate in the suction stroke has a low pressure. When
The high pressure oil on the discharge port side suddenly flows into the low pressure cylinder through the cylinder port, causing a large pressure fluctuation, and the pulsation accompanying this pressure fluctuation causes vibration and noise of the hydraulic pump. There is a problem of doing.

To solve such a problem, for example, Japanese Patent Laid-Open No. 63-63
JP-A-159678 discloses a pressure accumulating chamber for accumulating pressure oil introduced into a cylinder, and an oil passage having one end opening to the pressure accumulating chamber and the other end opening to a switching unit located between ports of a valve plate. A hydraulic pump provided with and has been proposed.

According to this hydraulic pump, each cylinder that slides on the switching portion of the valve plate opens the discharge port after the communication with the suction port is cut off, and the pressure oil in the pressure accumulating chamber is changed to oil. By introducing it into the cylinder through the passage, the pressure in the cylinder is increased to near the pressure on the discharge port side. Therefore, when the cylinder opens to the discharge port, the pressure oil on the discharge port side is prevented from rapidly flowing into the cylinder, and a large pressure fluctuation can be prevented. Then, pressure oil on the discharge port side is quickly filled into the pressure accumulation chamber that has become low pressure by introducing pressure oil into the cylinder, and then pressure oil is introduced into the cylinder that has lost communication with the suction port. To prepare for.

[0009]

By the way, when the hydraulic pump is operating, the flow rate of the pressure oil discharged from the discharge port (pump discharge flow rate) is usually the rotation angle θ of the cylinder block as shown in FIG. 9, for example. Is fluctuating with
Period A in which the pump discharge flow rate Q takes a value near the minimum value Qmin
And the period B having a value near the maximum value Qmax appear periodically. Here, the period A corresponds to a period from when the cylinder is disconnected from the suction port to when the cylinder is opened to the discharge port, and the period B is after the cylinder is communicated with the discharge port and then to the next cylinder. It is considered to correspond to the period until the communication with the suction port is cut off. The periodic fluctuation of the pump discharge flow rate Q as described above causes the pulsation during the operation of the hydraulic pump, and the minimum value Qmi
The magnitude of the pulsation also changes according to the magnitude of the difference (variation width) between n and the maximum value Qmax.

On the other hand, in the above-described conventional hydraulic pump, after the pressure oil in the pressure accumulating chamber is introduced into the cylinder whose communication with the suction port is cut off, the pressure port from the discharge port to the pressure accumulating chamber becomes low pressure. It is considered that the pressure oil is replenished within the period A described above. As described above, when a part of the pressure oil in the discharge port is filled in the pressure accumulating chamber in the period A in which the pump discharge flow rate Q takes a value near the minimum value Qmin, the pump discharge flow rate Q in the period A changes from the minimum value Qmin. It is further reduced and the difference from the maximum value Qmax is enlarged. As a result, there is a problem in that the fluctuation range of the pump discharge flow rate Q is increased, which promotes pulsation during the operation of the hydraulic pump.

Further, in the above-described hydraulic pump according to the prior art, since the oil passage for connecting the cylinder, which is disconnected from the suction port, and the pressure accumulating chamber are not provided with a throttle means or the like, the cylinder and the pressure accumulating chamber are separated from each other. When communicating via the oil passage, the pressure oil in the pressure accumulating chamber suddenly ejects into the cylinder, and the inner wall of the cylinder, the cylinder port, etc. are damaged by cavitation erosion due to the pressure oil and foreign matter in the pressure oil. There is a problem that pump efficiency and life are reduced.

The present invention has been made in view of the above-mentioned problems of the prior art. When each cylinder communicates with the high pressure side port, the pressure fluctuation generated between the high pressure side port and the cylinder is suppressed, and pulsation and the accompanying pulsation occur. It is an object of the present invention to provide an axial piston type hydraulic rotating machine capable of reducing vibration and noise.

[0013]

In order to solve the above-mentioned problems, the present invention provides a casing, a rotary shaft rotatably provided in the casing, and a rotary shaft located in the casing. A cylinder block that is provided so as to rotate integrally and is formed with a plurality of cylinders that are spaced apart in the circumferential direction, and is slidably inserted into each cylinder of the cylinder block. A plurality of pistons that are axially displaced, and a valve plate that is provided between the casing and the end surface of the cylinder block and that has a low-pressure side port and a high-pressure side port that intermittently communicate with each of the cylinders. It is applied to the axial piston type hydraulic rotary machine.

The feature of the structure adopted by the invention of claim 1 is that a pressure accumulating chamber for accumulating the pressure oil introduced into the cylinder, one end side of the pressure accumulating chamber and the other end side of the valve plate. A first oil passage for introducing pressure oil in the pressure accumulating chamber into a cylinder opened to a switching portion located between the ports and disconnected from the low pressure side port, and a middle portion of the first oil passage. The first throttle means provided and one end side thereof opens to the pressure accumulating chamber and the other end side thereof opens between the high pressure side port of the valve plate and the other end side of the first oil passage, and the low pressure side. A second oil passage for introducing pressure oil on the high pressure side port side into the pressure accumulating chamber after a cylinder disconnected from the port communicates with the high pressure side port, and provided in the middle of the second oil passage. The second diaphragm means is provided.

The invention according to claim 2 is provided with a third oil passage communicating the first oil passage and the high pressure side port of the valve plate, and provided in the middle of the third oil passage. A check valve that allows only the flow of pressure oil from the first oil passage to the high pressure side port, and the pressure in the cylinder disconnected from the low pressure side port is lower than the pressure in the high pressure side port. When it is also high, the pressure oil in the cylinder is configured to flow out to the high pressure side port via the third oil passage.

Further, the invention according to claim 3 is that the first oil passage is provided with a check valve which allows only the outflow of the pressure oil from the pressure accumulating chamber.

Further, in the invention of claim 4, the other end side of each of the first and second oil passages is located at the switching portion of the valve plate and is within a sliding locus in which each cylinder slides. It is configured to be installed in.

[0018]

According to the structure of the first aspect, the piston reciprocates in each cylinder formed in the cylinder block by the rotation of the cylinder block along with the rotating shaft. Then, when the cylinder communicates with the low pressure side port, the working oil is sucked into the cylinder from the low pressure side port, and when the cylinder communicates with the high pressure side port, the working oil in the cylinder is pressurized by the piston and becomes high pressure oil. Discharge to the side port. In this case, when the communication between the cylinder sliding on the valve plate and the low pressure side port is cut off as the cylinder block rotates, the pressure is accumulated in the cylinder via the first oil passage and the first throttle means. Since the pressure in the chamber is introduced and the pressure in the cylinder gradually rises to near the pressure on the high-pressure side port, when the cylinder communicates with the high-pressure side port, the pressure oil on the high-pressure side port suddenly enters the cylinder. Can be suppressed from flowing into. Then, the cylinder communicates with the high pressure side port and then communicates with the other end side of the second oil passage, so that the low pressure accumulating chamber gradually passes through the second oil passage and the second throttle means. The pressure oil on the high-pressure side port side is introduced and supplemented. In this case, the pressure oil is replenished in the pressure accumulating chamber after the cylinder communicates with the high pressure side port, that is, during the period when the discharge flow rate on the high pressure side port is the maximum, so the maximum discharge flow rate that causes pulsation And the minimum discharge flow rate can be reduced to reduce the pulsation.

According to the second aspect of the invention, when the pressure in the cylinder becomes higher than the pressure on the high pressure side port side due to excessive pressurization by the piston, the pressure oil in the cylinder is Since it flows out to the high pressure side port through the oil passage, the first throttle means, the third oil passage and the check valve, the pressure difference between the pressure in the cylinder and the pressure on the high pressure side port can be reduced, and the cylinder It is possible to suppress pressure fluctuations that occur when communicating with the high-pressure side port.

Further, according to the structure of claim 3, even when the pressure in the cylinder becomes higher than the pressure in the high pressure side port by the check valve provided in the first oil passage, The pressure oil flows out to the high pressure side port without flowing back into the pressure accumulating chamber.

Further, according to the structure of claim 4, the other end side of each of the first and second oil passages is located in the switching portion of the valve plate and is within the sliding locus in which each cylinder slides. By providing the cylinders, each cylinder formed in the cylinder block surely communicates with the first and second oil passages during the transition from the low pressure side port to the high pressure side port, so that each cylinder communicates with the high pressure side port. In each case, the pressure difference between the pressure in each cylinder and the pressure on the high-pressure side port side can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 8 by taking a swash plate type hydraulic pump as an example.

In the figure, reference numeral 1 denotes a casing which forms an outer shell of a hydraulic pump, and the casing 1 is composed of a bottomed cylindrical casing body 2 and a lid body 3 for closing an open end of the casing body 2. A shaft insertion hole 3A is formed in the center of the lid 3 in the axial direction to insert a rotary shaft 4 described later.

Reference numeral 4 denotes a rotary shaft rotatably supported by the casing 1 via a bearing 5, and the rotary shaft 4 is the casing 1.
It is projected to the outside through a shaft insertion hole 3A formed in the lid body 3 constituting the.

Reference numeral 6 denotes a cylinder block which is located inside the casing 1 and is spline-coupled to the rotary shaft 4 so as to rotate integrally with the rotary shaft.
A plurality of (7 in this example) cylinders 7, 7, ... Are bored in the axial direction so as to be spaced apart from each other in the circumferential direction.
Eyebrow-shaped cylinder ports 7A, 7A, ... Opening to the sliding surface 6A of the cylinder block 6 are formed.

Reference numerals 8, 8, ... Depict a plurality of pistons reciprocally inserted in each cylinder 7, and a spherical joint portion 8A is formed at the tip of each piston 8 protruding from the cylinder block 6. Has been done. Are a plurality of shoes provided on the outer peripheral side of the spherical joint portion 8A of each piston 8, and the shoes 9 are slidably fitted to the spherical joint portion 8A.

Reference numeral 10 denotes a swash plate provided between the lid 3 and the cylinder block 6, and the front surface side (cylinder block 6 side) of the swash plate 10 is a sliding surface on which the shoes 9 rotate while slidingly contacting each other. 10A, and the back side is a semi-cylindrical sliding portion 10B slidably fitted in a concavely curved guide groove 11 formed in the lid 3. A shaft insertion hole 10C is formed in the center of the swash plate 10 so that the diameter gradually increases from the front surface side to the back surface side. The tip end side of the rotary shaft 4 is inserted into the shaft insertion hole 10C. It has become. And swash plate 1
When the tilting angle with respect to the rotary shaft 4 is changed by a tilting drive mechanism (not shown), the stroke amount of each piston 8 is appropriately adjusted to variably control the displacement of the hydraulic pump. ing.

Reference numeral 12 is an annular shoe retainer fixed to the sliding surface 10A of the swash plate 10 while engaging with the outer peripheral side of each shoe 9, and the shoe retainer 12 slides each shoe 9 on the swash plate 10. It guides along an annular orbit on the moving surface 10A.

Reference numeral 13 denotes a valve plate disposed between the casing body 2 of the casing 1 and the cylinder block 6, and the valve plate 13 has a low-pressure eyebrow shape as shown in FIGS. 2 to 5. The suction port 14 as a side port and the discharge port 15 as a high pressure side port are provided so as to extend in the circumferential direction so as to be substantially symmetrical. The suction port 14 and the discharge port 15 are always in communication with a suction passage 16 and a discharge passage 17 formed in the bottom portion of the casing body 2, and the cylinder block 6 rotates with respect to the valve plate 13 so that each cylinder The cylinder port 7A of No. 7 is intermittently communicated. Further, a bottom dead center side switching portion 13A and a top dead center side switching portion 13B are provided between the intake port 14 and the discharge port 15 of the valve plate 13, and each cylinder 7 sliding on the valve plate 13 is provided. Is disconnected from the suction port 14 on the bottom dead center side switching portion 13A,
Communication with the discharge port 15 is blocked on the top dead center side switching portion 13B.

Reference numeral 18 denotes a pressure accumulating chamber located at the bottom dead center side switching portion 13A side and provided at the bottom of the casing main body 2. The pressure accumulating chamber 18 has, for example, a concave portion formed at the bottom of the casing main body 2. It is formed by sealing with a sealing plug 19 and stores pressure oil to be introduced into each cylinder 7 as described later.

Reference numeral 20 is a first oil passage for communicating each cylinder 7 with the pressure accumulating chamber 18, and the first oil passage 20 is formed so as to penetrate the bottom portion of the casing body 2 and the valve plate 13 and has one end thereof. The side 20A opens to the accumulator chamber 18, and the other end side 2
0B is the bottom dead center side switching portion 13 of the valve plate 13 as shown in FIG.
It opens to A. The first oil passage 20 is connected to the cylinder port 7A of each cylinder 7 that slides on the valve plate 13.
The hydraulic fluid stored in the pressure accumulating chamber 18 is introduced into the cylinder 7 via the cylinder port 7A by communicating with the cylinder 7.

Reference numeral 21 denotes a first throttle valve provided in the middle of the first oil passage 20, and the first throttle valve 21 is connected from the pressure accumulating chamber 18 to each cylinder 7 through the first oil passage 20. The flow rate of the pressure oil introduced into the cylinder 7 is adjusted to prevent the pressure oil from jetting into each cylinder 7.

Reference numeral 22 is a first valve provided between the pressure accumulating chamber 18 and the first throttle valve 21 and provided in the middle of the first oil passage 20.
Check valve of the first oil passage 20.
When the cylinder 7 communicates with the other end of the cylinder 7, the inflow of pressure oil from the cylinder 7 into the pressure accumulating chamber 18 is prohibited, and only the introduction of pressure oil from the pressure accumulating chamber 18 into the cylinder 7 is permitted.

A second oil passage 23 connects the discharge port 15 and the pressure accumulating chamber 18, and the second oil passage 23 is similar to the first oil passage 20 in that the bottom of the casing body 2 and the valve plate 13 are connected. Is formed so as to penetrate through the first oil passage 2 and one end side 23A thereof is open to the pressure accumulating chamber 18, and the other end side 23B is the first oil passage 2
It is located between the other end side 20B of 0 and the discharge port 15 and opens to the bottom dead center side switching portion 13A of the valve plate 13. The second oil passage 23 communicates with the discharge port 15 after the cylinder port 7A, which is disconnected from the suction port 14, and then communicates with the cylinder port 7A. Is introduced into the pressure accumulating chamber 18 through the cylinder port 7A.

Here, the other end side 20B of the first oil passage 20
The other end 23B of the second oil passage 23 is provided at a position of a radius R from the center of the valve plate 13 as shown in FIG. It is smaller than the radius R1 of the outer circular arc that determines the eyebrow shape and larger than the radius R2 of the inner circular arc (R2 <R <
R1). That is, the other end side 20B of the first oil passage 20 and the other end side 2 of the second oil passage 23.
3B is located in the bottom dead center side switching portion 13A of the valve plate 13 and is disposed within the sliding locus of each cylinder port 7A, and each cylinder 7 is reliably transferred from the suction port 14 to the discharge port 15. The first oil passage 20 and the second oil passage 23 are communicated with each other.

Reference numeral 24 denotes a second throttle valve provided in the middle of the second oil passage 23, and the second throttle valve 24 is introduced into the pressure accumulating chamber 18 via the second oil passage 23. The pressure of the pressure oil is adjusted.

25 is the first oil passage 20 and the discharge port 15.
Shows a third oil passage communicating with the third oil passage 2
5, the one end side 25A branches from between the first throttle valve 21 and the first check valve 22 in the first oil passage 20,
The other end side 25B is connected to the discharge port 1 via the second check valve 26.
It opens to 5. When the pressure in the cylinder 7 that is disconnected from the suction port 14 is higher than the pressure in the discharge port 15, the third oil passage 25 transfers the pressure oil in the cylinder 7 to the first oil. Discharge port 15 through passage 20
The second check valve 26 permits only the flow of the pressure oil from the cylinder 7 to the discharge port 15.

The hydraulic pump according to this embodiment has the above-mentioned structure, and its operation will be described below.

First, when the drive source is operated, the rotary shaft 4 and the cylinder block 6 splined to the rotary shaft 4 are connected.
And rotate together. As a result, the cylinder block 6
The piston 8 inserted into each cylinder 7 rotates together with the cylinder block 6, and the shoe 9 with which the spherical joint portion 8A of the piston 8 is fitted is guided by the shoe retainer 12 while sliding surface 10A of the swash plate 10A. Rotate over. At this time, the swash plate 10
Since the sliding surface 10A has a predetermined tilting angle, the piston 8 is located at the top dead center position where the piston 8 is most advanced into the cylinder 7 and the bottom position where the piston 8 is most extended from the cylinder 7 during one rotation of the cylinder block 6. Strokes to and from the dead center position.

Here, during the half rotation in which the piston 8 strokes from the top dead center position to the bottom dead center position, the cylinder port 7A communicates with the suction port 14, and the suction port 16 allows the cylinder port 7A to communicate with the cylinder. 7 is a suction stroke for sucking the hydraulic oil. On the other hand, during the half rotation in which the piston 8 strokes from the bottom dead center position to the top dead center position, the cylinder port 7A communicates with the discharge port 15 and pressurizes the hydraulic oil sucked into the cylinder 7 while the discharge port 15 is being pressed. The discharge stroke is to discharge to the discharge passage 17 through the discharge passage 17. In this way, the rotary shaft 4 is rotationally driven to reciprocally move the piston 8 in the cylinder 7, whereby the suction stroke and the discharge stroke are repeated,
Pump operation is performed.

The swash plate 10 is appropriately tilted along the guide groove 11 by the tilting drive mechanism to change the displacement capacity in the cylinder 7, thereby the pressure discharged to the discharge port 15 and the discharge passage 17. The oil volume can be controlled.

Here, in the hydraulic pump according to the present embodiment,
By providing the pressure accumulating chamber 18, the first oil passage 20, the second oil passage 23, the third oil passage 25, and the like, the pressure in each cylinder 7 and the discharge port 15 during the series of pump operations as described above. The pressure difference from the side pressure is reduced, and the discharge port 1
The pressure fluctuation of the pressure oil discharged to the 5 side is suppressed, and each cylinder is formed by the pressure accumulating chamber 18, the first oil passage 20, the second oil passage 23, the third oil passage 25, and the like. 7
The operation of reducing the pressure difference between the internal pressure and the pressure on the discharge port 15 side will be described below with reference to FIGS. 2 to 8.

First, as shown in FIG. 2, one of the cylinders 7 rotating in the direction of the arrow F together with the rotating shaft 4 reaches the bottom dead center side switching portion 13A of the valve plate 13 from the terminal end side of the suction port 14, The communication between the cylinder port 7A of the cylinder 7 and the suction port 14 is cut off. At this time, the pressure accumulating chamber 18 is filled with the pressure oil on the discharge port 15 side through the other cylinder 7 and the second oil passage 23 which are already in communication with the discharge port 15.

Next, as the rotary shaft 4 further rotates in the direction of arrow F, the cylinder port 7A, which has been disconnected from the suction port 14, is closed in the first oil passage 20 as shown in FIGS. It communicates with the other end side 20B.

At this time, when the pressure in the cylinder 7 is lower than the pressure in the discharge port 15, the pressure oil filled in the pressure accumulating chamber 18 is the first oil passage 20 and the first throttle. Valve 2
1 and the cylinder port 7A, and is gradually introduced into the cylinder 7. As a result, the pressure in the cylinder 7 is increased to near the pressure in the discharge port 15, and when the cylinder port 7A communicates with the discharge port 15, the discharge port 1
It is possible to prevent the pressure oil in 5 from flowing into the cylinder 7.
Moreover, since the first throttle valve 21 provided in the middle of the first oil passage 20 can prevent the pressure oil in the pressure accumulating chamber 18 from suddenly ejecting into the cylinder 7, the inner wall of the cylinder 7 and the cylinder port can be prevented. It is possible to prevent 7A and the like from being damaged by cavitation erosion.

On the other hand, when the pressure in the cylinder 7 is higher than the pressure in the discharge port 15 due to excessive pressurization by the piston 8, for example, the pressure oil in the cylinder 7 is It flows out to the discharge port 15 through the oil passage 20 and the third oil passage 25. This prevents the pressure oil in the cylinder 7 from suddenly flowing out to the discharge port 15 when the pressure in the cylinder 7 is reduced to near the pressure in the discharge port 15 and the cylinder port 7A communicates with the discharge port 15. it can.

Next, when the rotary shaft 4 further rotates in the direction of the arrow F, the cylinder port 7A, which has been disconnected from the suction port 14, loses its communication with the discharge port 1 as shown in FIGS.
It communicates with the starting end side of 5. At this time, since the pressure difference between the pressure in the cylinder 7 corresponding to the cylinder port 7A and the pressure in the discharge port 15 is reduced as described above, the pressure oil rapidly flows between the cylinder 7 and the discharge port 15. It is possible to suppress various pressure fluctuations and reduce pulsation during the operation of the hydraulic pump.

When the rotary shaft 4 further rotates in the direction of arrow F after the cylinder port 7A communicates with the start end side of the discharge port 15, as shown in FIGS. 7 and 8, the cylinder port 7A causes the second oil to flow. It communicates with the other end side 23B of the passage 23. At this time, since the pressure oil in the pressure accumulating chamber 18 is introduced into the cylinder 7 via the first oil passage 20 as described above, the pressure in the pressure accumulating chamber 18 becomes lower than the pressure on the discharge port 15 side. If the pressure oil on the discharge port 15 side is present, the cylinder port 7A, the second oil passage 23 and the second oil passage 23
Is gradually introduced into the accumulator chamber 18 via the throttle valve 24 of
The pressure in the pressure accumulating chamber 18 is increased to near the pressure on the discharge port 15 side. In this way, when the pressure in the cylinder 7 at which communication with the suction port 14 is cut off next is lower than the pressure on the discharge port 15 side, it is introduced into the cylinder 7 via the first oil passage 20 or the like. The pressure oil to be filled is filled in the pressure accumulating chamber 18, and then the pressure oil is introduced into the cylinder 7 whose communication with the suction port 14 is cut off.

Here, the pressure oil is filled from the discharge port 15 into the pressure accumulating chamber 18 after the cylinder 7 communicates with the discharge port 15, that is, in the period B shown in FIG. The maximum value Qmax of the pump discharge flow rate Q is reduced by the amount of pressure oil filled in the pump discharge flow rate Q.
The difference between the maximum value Qmax and the minimum value Qmin becomes small. As a result, the fluctuation range of the pump discharge flow rate Q becomes smaller, and the pulsation during the operation of the hydraulic pump can be suppressed more effectively.

As described above, in the present embodiment, when the pressure in the cylinder 7 which is disconnected from the suction port 14 is lower than the pressure on the discharge port 15 side, the first oil passage 20
By introducing the pressure oil in the pressure accumulating chamber 18 into the cylinder 7 via the above, or when the pressure in the cylinder 7 is higher than the pressure on the discharge port 15 side, the first oil passage 20,
Since the pressure oil in the cylinder 7 flows out to the discharge port 15 via the third oil passage 25 or the like, the pressure difference between the pressure in the cylinder 7 and the pressure on the discharge port 15 side is reduced. It is possible to remarkably reduce the pressure fluctuation caused by the rapid flow of pressure oil between each cylinder 7 and the discharge port 15, and to suppress the pulsation during the operation of the hydraulic pump.

Moreover, by providing the first throttle valve 21 in the middle of the first oil passage 20, the introduction of the pressure oil from the pressure accumulating chamber 18 to the cylinder 7 and the introduction of the pressure oil from the cylinder 7 to the discharge port 15 are performed. Since the discharge can be performed gently,
It is possible to reliably prevent the cylinder 7, the discharge port 15 and the like from being damaged by the cavitation erosion due to the pressure oil jetted.

Further, the pressure oil in the discharge port 15 is stored in the pressure accumulating chamber 1
The second oil passage 23 for introducing into the cylinder 8 is connected to the cylinder 7 after the cylinder port 7A communicates with the discharge port 15.
And the pressure accumulating chamber 18 are connected to each other, the pressure accumulating chamber 1 after the pressure oil in the pressure accumulating chamber 18 is introduced into the cylinder 7
The pressure oil can be replenished to 8 in the period when the flow rate of the pressure oil discharged to the discharge port 15 is substantially maximum. Therefore, the maximum value of the pump discharge flow rate is reduced by the amount of the pressure oil filled in the pressure accumulating chamber 18, so that the difference between the maximum value and the minimum value of the pump discharge flow rate, that is, the fluctuation range of the pump discharge flow rate is reduced. It is possible to reduce the size, and it is possible to more effectively suppress pulsation during the operation of the hydraulic pump.

Further, the other end side 20B of the first oil passage 20
Also, since the other end side 23B of the second oil passage 23 is provided in the sliding locus where the cylinder 7 slides at the bottom dead center side switching portion 13A of the valve plate 13, each cylinder 7 is sucked. During the transition from the port 14 to the discharge port 15, it surely communicates with the first oil passage 20 and the second oil passage 23. As a result, in each case where each cylinder 7 communicates with the discharge port 15, the pressure difference between the pressure in each cylinder 7 and the pressure in the discharge port 15 can be reliably reduced, and pulsation during operation of the hydraulic pump can be ensured. Can be reliably suppressed. Moreover, the first oil passage 20 and the second oil passage 23
Since it is not necessary to provide a special communication portion or the like in each cylinder 7 in order to communicate the cylinder with each cylinder 7, it is possible to simplify the structure.

In the above embodiment, the case where the swash plate type hydraulic pump is used as the axial piston type hydraulic rotating machine has been described as an example, but the present invention is not limited to this, and for example, the swash shaft type is used. The present invention may be applied to the hydraulic pump described in (1) above, and may also be suitably used for a hydraulic motor or the like as a drive source of hydraulic equipment.

[0055]

As described in detail above, according to the first aspect of the present invention, when the pressure in the cylinder disconnected from the low pressure side port is lower than the pressure on the high pressure side port, the first By introducing the pressure in the accumulator into the cylinder via the oil passage, the pressure difference between the pressure in the cylinder and the pressure on the high-pressure side port side is reduced. It is possible to remarkably reduce the pressure fluctuation due to the rapid flow of hydraulic oil, and to effectively suppress the pulsation during the operation of the hydraulic pump. Moreover, the cylinder is configured to communicate with the second oil passage after communicating with the high pressure side port, so that the pressure oil from the high pressure side port is supplemented to the low pressure accumulator chamber by the hydraulic oil at the high pressure side port. Is performed during a period in which the maximum discharge flow rate is substantially maximum, the difference between the maximum discharge flow rate and the minimum discharge flow rate during operation of the rotating machine is reduced, the fluctuation range of the discharge flow rate is reduced, and pulsation is further effectively reduced. can do.

Further, according to the second aspect of the invention, even when the pressure in the cylinder becomes higher than the pressure on the high pressure side port side due to the excessive pressurization by the piston, the pressure in the cylinder is the first oil. Since it flows out to the high-pressure side port through the passage, the first throttle means, the third oil passage and the check valve, the pressure difference between the pressure in the cylinder and the pressure on the high-pressure side port can be reduced, and the high pressure of the cylinder It is possible to suppress the pressure fluctuation that occurs when communicating with the side port.

Further, according to the invention of claim 3, by providing the check valve in the first oil passage, when the pressure in the cylinder becomes higher than the pressure in the high pressure side port side, The pressure oil can be surely flown to the high pressure side port without flowing back into the pressure accumulating chamber.

Further, according to the invention of claim 4, the other end side of each of the first and second oil passages is located in the switching portion of the valve plate and is within the sliding locus in which each cylinder slides. Since it is configured such that each cylinder formed in the cylinder block is surely communicated with the first and second oil passages during the transition from the low pressure side port to the high pressure side port, each cylinder has a high pressure. In each case of communicating with the side port, it is possible to reliably reduce the pressure difference between the pressure in each cylinder and the pressure on the high pressure side port side.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a swash plate type hydraulic pump according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view as seen from the direction of arrows II-II in FIG.

FIG. 3 is an operation explanatory diagram at the same position as in FIG. 2, showing a state in which a cylinder port communicates with a first oil passage.

4 is a development view showing a positional relationship between a cylinder port and first, second and third oil passages in FIG. 3. FIG.

FIG. 5 is an operation explanatory diagram at the same position as in FIG. 2, showing a state in which the cylinder port communicates with the discharge port.

6 is a development view showing a positional relationship between a cylinder port and first, second, and third oil passages in FIG.

FIG. 7 is an operation explanatory diagram at the same position as in FIG. 2, showing a state in which a cylinder port communicates with a second oil passage.

8 is a development view showing a positional relationship between a cylinder port and first, second and third oil passages in FIG. 7. FIG.

FIG. 9 is a characteristic diagram showing a relationship between a pump discharge flow rate of a hydraulic pump and a rotation angle of a cylinder block.

[Explanation of symbols]

 1 Casing 4 Rotating Shaft 6 Cylinder Block 7 Cylinder 7A Cylinder Port 8 Piston 13 Valve Plate 13A Bottom Dead Center Side Switching Port 14 Suction Port (Low Pressure Side Port) 15 Discharge Port (High Pressure Side Port) 18 Accumulation Chamber 20 First Oil Passage 21 1st throttle valve 23 2nd oil passage 24 2nd throttle valve 25 3rd oil passage

Claims (4)

[Claims] 1. A casing, a rotating shaft rotatably provided in the casing, a rotating shaft located in the casing so as to rotate integrally with the rotating shaft, and a plurality of members spaced apart from each other in the circumferential direction. A cylinder block in which a cylinder is formed, a plurality of pistons slidably inserted into the cylinders of the cylinder block, and axially displaced as the cylinder block rotates, and the casing and the cylinder block. In an axial piston type hydraulic rotary machine including a valve plate provided between the end surface and a low pressure side port and a high pressure side port which are intermittently communicated with each of the cylinders, and is introduced into the cylinder. A pressure accumulator chamber for storing pressure oil and one end side of which opens in the pressure accumulator chamber and the other end side of which opens in a switching portion located between the respective ports of the valve plate, so that communication with the low pressure side port is established. A first oil passage for introducing pressure oil in the pressure accumulating chamber into the leaned cylinder, a first throttle means provided in the middle of the first oil passage, and one end side of which opens to the pressure accumulating chamber and The high pressure side is opened after the cylinder whose end is opened between the high pressure side port of the valve plate and the other end side of the first oil passage and is disconnected from the low pressure side port communicates with the high pressure side port. An axial piston type liquid, comprising a second oil passage for introducing pressure oil on the side port side into the pressure accumulating chamber, and a second throttle means provided in the middle of the second oil passage. Pressure rotating machine. 2. A third oil passage that connects the first oil passage and a high-pressure side port of the valve plate, and a third oil passage provided in the middle of the third oil passage. A check valve which allows only the flow of pressure oil to the high pressure side port, and when the pressure in the cylinder disconnected from the low pressure side port is higher than the pressure in the high pressure side port, the inside of the cylinder 2. The axial piston type hydraulic rotating machine according to claim 1, wherein the pressure oil is discharged to the high pressure side port via the third oil passage. 3. The axial piston type hydraulic rotating machine according to claim 1, wherein the first oil passage is provided with a check valve which allows only the outflow of pressure oil from the pressure accumulating chamber. 4. The other end side of each of the first and second oil passages is provided in a sliding locus where the cylinder slides at a switching portion of the valve plate. , 2 or 3, the axial piston type hydraulic rotary machine.