WO2016167070A1

WO2016167070A1 - Rotational-speed-controlling variable piston pump

Info

Publication number: WO2016167070A1
Application number: PCT/JP2016/058125
Authority: WO
Inventors: 博一平出; 祐也塚田
Original assignee: 油研工業株式会社
Priority date: 2015-04-14
Filing date: 2016-03-15
Publication date: 2016-10-20
Also published as: JP2016200115A; CN107407263A; JP6280517B2; CN107407263B

Abstract

Provided is a rotational-speed-controlling variable piston pump with which it is possible to satisfactorily avoid abnormal pressures in the bore chamber of a cylinder block with a simple configuration, without causing loss of pump efficiency or increases in cost. The present invention provides a rotational-speed-controlling variable piston pump in which pistons move back and forth within a bore at a stroke suited to the angle of inclination of a swash plate along with the rotation of a cylinder block, whereby hydraulic oil is drawn into a bore chamber from an intake oil passage formed in a casing, via an intake port of a port plate against which the cylinder block slides, and the hydraulic oil is discharged to a discharge oil passage formed in the casing, via a discharge port of the port plate; wherein an abnormal-pressure-avoiding oil pressure circuit, which releases the hydraulic oil in the bore chamber out of the bore chamber when the pressure in the bore chamber positioned between the intake port and the discharge port of the port plate exceeds a predetermined pressure, is provided as being incorporated in the same unit structure within the same casing.

Description

Variable piston pump for speed control

The present invention relates to, for example, a two-capacity variable piston pump for controlling the rotational speed, and more particularly to means for avoiding abnormal pressure in the bore chamber of the cylinder block.

Among various types of hydraulic piston pumps, for example, there are those that are driven to rotate by an AC servo motor, and the amount of discharge can be varied by controlling the number of rotations. Therefore, the quantified one is used.

In addition, as shown in the circuit diagram of FIG. 3, in such a piston pump for controlling the rotational speed, the electromagnetic switching valve 118 has a large capacity with a large swash plate angle and a small capacity with a small inclination angle. There are two displacement variable piston pumps 100 that can be switched to.

As shown in the cross-sectional view of FIG. 4, the swash plate type piston pump 100 includes a plurality of bores 104 in parallel with the rotating shaft 102 inside a cylinder block 103 that rotates integrally with the rotating shaft 102 driven by a motor. , And a swash plate 107 having an inclined surface with which each end shoe 106 of the piston 105 accommodated in each bore 104 is slidably contacted is supported on the rotating shaft 102 so as to be inclined. As the block 103 rotates, each piston 105 reciprocates in the bore 104 with a stroke corresponding to the inclination angle of the swash plate 107, so that hydraulic oil is passed through the bore chamber 109 formed by the bore 104 and the piston 105. Suction and discharge.

In the variable displacement piston pump 100, when the swash plate 107 is in a state where the operation of the pump discharge pressure is cut off while the electromagnetic switching valve 118 is turned on as shown in FIG. When the electromagnetic switching valve 118 is turned OFF, a part of the pump discharge pressure acts on the operation piston 117 as shown in FIG. 4B. Then, the operating piston 117 presses the swash plate 107 to a small inclination angle position at which the discharge amount is minimum against the urging force of the spring mechanism 116. In this two-capacity type, one pump can have the function of two pumps, and a wider range of use can be achieved with the same motor capacity.

Further, the piston pump 100 has a port plate 108 in which a suction port 113 and a discharge port 114 for distributing hydraulic oil to each bore chamber 109 are formed in an arc shape as shown in FIG. It is fixed to the cover 120. The discharge port 114 and the suction port 113 communicate with the discharge oil passage 121 and the suction oil passage of the casing, respectively. On the other hand, on the end face of the cylinder block 103, a kidney port 112 serving as a discharge port / suction port for the hydraulic oil in each bore chamber 109 is opened and slides with respect to the port plate 108, and each kidney port 112 discharges. The hydraulic oil is discharged / sucked over the port 114 or the suction port 113.

The kidney port 112 is normally shut off from the suction port 113 before completely shifting from the suction port 113 to the discharge port 114, and the piston 105 in the corresponding bore 104 is closed after the shut-off. It is designed to reach the bottom dead center shown in FIG. Therefore, in the bore chamber 109, the pressure decreases until the bottom dead center is reached after the kidney port 112 and the suction port 113 are shut off, and cavitation causing high frequency is likely to occur. At the time when the kidney port 112 shifts to the discharge port 114, the piston 105 starts moving from the bottom dead center in the direction of compressing the volume of the bore chamber 109, and the pressure in the bore chamber 109 rises rapidly, causing an oil hammer. There is a risk of generating. Such a sudden change in pressure causes noise generation. To prevent this, as shown in FIG. 5B, at least the end of the discharge port 114 of the port plate 108 is connected to the suction port 113. Providing a bowl-shaped escape groove 115 extending toward the front is performed (for example, see Patent Document 1).

JP 2002-31039 A

However, in a swash plate type two-capacity variable piston pump, when a piston of a certain bore is at bottom dead center and its kidney port is located between the suction port and the discharge port of the port plate, the switching is performed by switching the electromagnetic switching valve. When the plate shifts from the large inclination angle of FIG. 4 (a) to the small inclination angle of FIG. 4 (b), the piston is pushed in the compression direction while the bore chamber is sealed by the port plate, and the pressure in the bore chamber is increased. Suddenly increased and abnormal pressure was generated, which could cause damage to the cylinder block.

Therefore, it was necessary to take measures to avoid the occurrence of such abnormal pressure in the bore chamber. For example, as shown in FIG. 6, by extending the bowl-shaped escape groove 115 of the discharge port 114 of the port plate so as to reach the kidney port 112 located between the suction port 113 and the discharge port 114. A method to suppress the abnormal pressure by preventing the bore chamber from being completely contained was considered. However, in this case, the volumetric efficiency is deteriorated, and the energy saving performance as a pump is sacrificed.

As another method, the cylinder block itself may be made of a material having high mechanical strength, but the cost is unavoidable. In addition, in the method of reducing the pressure receiving area by reducing the diameter of the operating piston that receives a part of the pump discharge pressure through the electromagnetic switching valve, the minimum control pressure that maintains the small inclination angle of the swash plate is deteriorated. I will. Further, it is conceivable to suppress the pressure in the operation piston chamber by using a pressure reducing valve. However, in addition to an increase in cost, there is a problem that an instantaneous surge pressure is generated due to the responsiveness of the pressure reducing valve. Thus, there has been no effective means for avoiding abnormal pressure in the bore chamber without lowering pump efficiency and increasing costs.

In view of the above problems, the object of the present invention is to prevent abnormal pressure generation in the bore chamber of the cylinder block that is enclosed between the discharge port and the suction port of the port plate when the swash plate is switched from a large inclination angle to a small inclination angle. An object of the present invention is to provide a variable piston pump for controlling the rotational speed that can be satisfactorily avoided while having a simple structure without incurring a reduction in pump efficiency and high cost.

In order to achieve the above object, a variable piston pump for controlling the rotational speed according to the first aspect of the present invention includes a rotating shaft that is rotationally driven by a motor, a cylinder block that rotates integrally with the rotating shaft, and the cylinder The block has a plurality of bores formed in parallel with the rotary shaft, pistons accommodated in the bores, and inclined surfaces on which end shoes of the pistons are slidably contacted, and are inclined to the rotary shaft. The swash plate that is supported is assembled as a single unit structure in the pump chamber formed of the inner space of the same casing, and the stroke according to the inclination angle of the swash plate as the rotary shaft and the cylinder block rotate. Thus, each piston reciprocates in the bore, so that the cylinder is formed from the suction oil passage formed in the casing in the bore chamber formed by the bore and the piston. A variable piston pump for controlling the number of revolutions that sucks hydraulic oil through a suction port of a port plate in sliding contact with the block and discharges the hydraulic oil to a discharge oil passage formed inside the casing through a discharge port of the port plate. In
When the pressure in the bore chamber located between the suction port and the discharge port of the port plate exceeds a predetermined pressure, an abnormal pressure avoiding hydraulic circuit that releases the hydraulic oil in the bore chamber to the outside of the bore chamber, It is provided by being incorporated in the unit structure in the same casing.

According to a second aspect of the present invention, there is provided the variable piston pump for controlling the rotational speed according to the first aspect, wherein the abnormal pressure avoiding mechanism is provided between the suction port and the discharge port. It has a safety valve which discharges hydraulic oil in the located bore chamber into the pump chamber.

According to a third aspect of the present invention, there is provided the variable piston pump for controlling the rotational speed according to the first aspect, wherein the abnormal pressure avoiding mechanism is provided between the suction port and the discharge port. A relief oil passage that communicates the bore chamber and the discharge oil passage through a check valve is provided.

In the variable piston pump for speed control according to the present invention, when the pressure in the bore chamber located between the suction port and the discharge port of the port plate exceeds a predetermined pressure by the abnormal pressure avoidance hydraulic circuit. Since the working oil in the bore chamber can be released to the outside of the bore chamber, the swash plate has a large capacity and a large inclination angle when the bore chamber is sealed at the bottom dead center between the suction port and the discharge port. Even if the piston is switched from a small tilt angle to a small tilt angle and the piston suddenly compresses the bore chamber, the hydraulic oil in the bore chamber is released and abnormal pressure is prevented from occurring, resulting in high cost. There is an effect that the risk of damaging the cylinder block can be avoided while maintaining the pump performance without depending on the increase. The abnormal pressure avoiding hydraulic circuit is provided integrally in the same casing, and can function with a simple configuration of being incorporated in the same unit structure of the piston pump.

It is a schematic block diagram of the variable piston pump for rotation speed control by 1st Example of this invention, (a) is a whole longitudinal cross-sectional view, (b) is a partial longitudinal cross-sectional view. FIG. 2 is an overall longitudinal sectional view showing a schematic configuration of a variable piston pump for controlling the rotational speed according to a second embodiment of the present invention. FIG. 2 is a hydraulic circuit diagram of a 2-capacity variable piston pump for controlling the rotational speed. It is a whole longitudinal cross-sectional view which shows schematic structure of the conventional variable piston pump for rotation speed control, (a) is a state with a large inclination angle (large discharge capacity) of a swash plate, (b) is a small inclination angle (small) of a swash plate. (Discharge capacity) state. It is a schematic plan view which shows a port plate in the state which overlapped with the cylinder block, (a) shows the whole port plate, (b) is an enlarged view of the part enclosed with the square of (a). It is the elements on larger scale which show the case where the escape groove of the discharge port of a port plate is extended.

In the variable speed piston pump for controlling the rotational speed of the present invention, a single unit structure is provided in the pump chamber formed of the inner space of the same casing, and the rotation shaft, the cylinder block that rotates integrally with the rotation shaft, and the cylinder block A plurality of bores formed in parallel with the rotation shaft, pistons accommodated in the bores, and inclined surfaces on which end shoes of the pistons are slidably contacted, can be inclined to the rotation shaft. A bore formed by the bore and the piston is assembled by assembling the supported swash plate and reciprocating the pistons in the bore with a stroke corresponding to the inclination angle of the swash plate as the cylinder block rotates. The hydraulic oil is sucked into the chamber from a suction oil passage formed inside the casing through a suction port of a port plate that is in sliding contact with the cylinder block. Hydraulic fluid is discharged to a discharge oil passage formed inside the casing through a discharge port of the front plate, and the pressure in the bore chamber located between the suction port and the discharge port of the port plate is determined in advance. An abnormal pressure avoiding hydraulic circuit for allowing the hydraulic oil in the bore chamber to escape to the outside of the bore chamber when the pressure is exceeded is provided in the unit structure in the same casing.

Therefore, when the bore chamber located between the suction port and the discharge port is confined at the bottom dead center, the swash plate is switched from a large tilt angle with a large capacity to a small tilt angle with a small capacity. Even if the bore chamber is rapidly compressed, the hydraulic fluid for avoiding abnormal pressure is released by the abnormal pressure avoiding hydraulic circuit to prevent the occurrence of abnormal pressure. The risk of damaging the cylinder block can be avoided while maintaining the performance. Moreover, the hydraulic circuit for avoiding abnormal pressure according to the present invention is provided integrally in the same casing and functions in a simple configuration of being incorporated in the same unit structure of the piston pump.

異常 First, as a hydraulic circuit for avoiding abnormal pressure, one using a safety valve is simple. Specifically, if a discharge passage that communicates the bore chamber located between the suction port and the discharge port to the pump chamber is provided, and a safety valve, that is, a relief valve is arranged immediately downstream of the bore chamber, The safety valve allows the hydraulic oil in the bore chamber to be discharged to the discharge passage when a predetermined pressure before the abnormal pressure is exceeded. When the pressure drops, the safety valve closes and the discharge passage is immediately shut off. .

It should be noted that the original piston pump unit portion may remain the conventional structure, and an abnormal pressure avoidance hydraulic circuit can be configured simply by incorporating the safety valve and the discharge passage into the same casing. Usually, a casing is integrally provided with a casing-like casing body and a casing cover so as to close the casing, the pump chamber is closed, and a discharge oil passage and a suction oil passage are formed inside the casing cover. The port plate is fixed to the inner surface of the casing cover so that the end surface of the cylinder block is in sliding contact. Accordingly, it is most convenient to form the safety valve and the discharge passage inside the casing cover. At this time, the end side of the discharge passage passes through the port plate and communicates with the corresponding bore chamber.

Also, as a simple hydraulic circuit for avoiding abnormal pressure, one using a check valve can be raised. Specifically, if a relief oil passage that connects the bore chamber located between the suction port and the discharge port and the discharge oil passage is formed, and a check valve is disposed immediately downstream of the bore chamber. When the predetermined pressure before the abnormal pressure is exceeded, the hydraulic oil in the bore chamber can be released from the check valve to the discharge oil passage through the oil passage, and if the pressure drops, the check valve releases the hydraulic oil. The oil passage is immediately closed. Also in this case, if the basic configuration is the same as that of the conventional piston pump unit, the check valve and the relief oil passage are formed inside the casing cover, and the end portion side of the relief oil passage penetrates the port plate. It is most convenient to have a configuration communicating with the bore chamber.

As described above, in any of the above abnormal pressure avoidance hydraulic circuits, the cylinder block is damaged without affecting the substantial pump performance, such as the deterioration of volumetric efficiency, although it is a simple configuration incorporated in the casing. Generation of abnormal pressure can be avoided.

As a first embodiment of the present invention, FIG. 1 shows a two-volume variable piston pump for controlling the number of revolutions equipped with an abnormal pressure avoidance hydraulic circuit using a safety valve. FIG. 1A is an overall longitudinal sectional view, and FIG. 1B is a partial sectional view showing an abnormal pressure avoiding hydraulic circuit.

The basic structure of the piston pump unit other than the abnormal pressure avoiding hydraulic circuit is the same as the example shown in FIGS. 3 and 4 in the two-capacity variable piston pump 1 for controlling the rotational speed according to the present embodiment.

That is, in a pump chamber 11 formed by closing a container-like casing body 10 with a casing cover 20, a rotary shaft 2 that is driven to rotate by a motor, and a cylinder block 3 that rotates integrally with the rotary shaft 2. A plurality of bores 4 formed in the cylinder block 3 in parallel with the rotary shaft 2, pistons 5 accommodated in the bores 4, and inclinations at which the end shoes 6 of the pistons 5 are in sliding contact with each other. The swash plate 7 having a surface and supported on the rotary shaft 2 so as to be tiltable is assembled as a single unit structure. Further, the swash plate 7 is directed toward the maximum tilt angle at which the maximum discharge capacity is obtained by the spring mechanism 16. The operating piston 17 is installed so as to be movable in a direction in which the swash plate 7 is pressed against the urging by the spring mechanism 16.

The operating piston 17 is set to be able to receive a part of the pump self-discharge pressure through an electromagnetic switching valve. When the electromagnetic switching valve is ON, a part of the action of the pump self-discharge pressure on the operation piston 17 is cut off, the swash plate 7 is biased to the maximum inclination angle by the spring mechanism 16, and the electromagnetic switching valve is turned OFF. Is switched, the part of the pump self-discharge pressure is applied to the operation piston 17, the operation piston 17 is moved, the swash plate 7 is pressed, and it is tilted to the minimum inclination angle that is the minimum discharge amount.

Each piston 5 of the cylinder block 3 reciprocates in the bore 4 with a stroke corresponding to the inclination angle of the swash plate 7 as the rotary shaft 2 and the cylinder block 3 rotate, and enters the bore chamber 9 into the casing. The working oil is sucked from the formed suction oil passage through the suction port of the port plate in sliding contact with the cylinder block, and the working oil is supplied to the discharge oil passage formed inside the casing through the discharge port of the port plate. Discharge.

In the present embodiment, as the abnormal pressure avoiding hydraulic circuit 30, a discharge passage 31 that communicates the bore chamber 9 located between the suction port and the discharge port of the port plate 8 to the pump chamber 11 is formed inside the casing cover 20. A safety valve 32 is formed at a position immediately downstream of the bore chamber 9 in the discharge passage 31. The discharge passage 31 includes a through hole 31 </ b> X that passes through the port plate 8 on the end side and communicates with the corresponding kidney port 12 of the bore chamber 9.

The two-volume variable piston pump 1 for controlling the rotational speed having the above-described configuration is configured such that the electromagnetic switching valve is turned off when the swash plate 7 with the electromagnetic switching valve turned on is driven in a large discharge capacity state at a large inclination angle. When switched, in the bore chamber 9 at the bottom dead center where the kidney port 12 is located between the suction port and the discharge port of the port plate 8, the swash plate 7 moves to a small inclination angle position where the discharge capacity becomes a small discharge capacity. Even if the piston 5 rises and sudden compression occurs due to the tilting, the safety valve 32 opens when the pressure exceeds the predetermined pressure, and the hydraulic oil in the bore chamber 9 is discharged into the discharge passage 31. .

The operation of the safety valve 32 as described above avoids the danger that the bore chamber 9 may generate an abnormal pressure that may cause the cylinder block 3 to be damaged. When the pressure in the bore chamber 9 falls below a predetermined value, the safety valve 32 is immediately closed, and the pump driving with a small discharge capacity is continued without any trouble by the swash plate 7 having a small inclination angle.

As a second embodiment of the present invention, a vertical displacement cross-sectional view of FIG. 2 shows a two-volume variable piston pump for controlling the rotational speed equipped with an abnormal pressure avoiding hydraulic circuit using a check valve.

The basic structure of the piston pump unit other than the abnormal pressure avoiding hydraulic circuit is the same as that of the first embodiment shown in FIG.

The abnormal pressure avoiding hydraulic circuit 40 in this embodiment includes a relief oil passage 41 that communicates the bore chamber 9 located between the suction port and the discharge port of the port plate 8 with the discharge oil passage 21 inside the casing cover 20. A check valve 42 is formed at a position immediately downstream of the bore chamber 9 of the relief oil passage 41 formed. The escape oil passage 41 includes a through hole 41 </ b> X that passes through the port plate 8 on the end side and communicates with the corresponding kidney port 12 of the bore chamber 9.

The two-volume variable piston pump 1 for controlling the rotational speed having the above-described configuration is configured such that the electromagnetic switching valve is turned off when the swash plate 7 with the electromagnetic switching valve turned on is driven in a large discharge capacity state at a large inclination angle. When switched, in the bore chamber 9 at the bottom dead center where the kidney port 12 is located between the suction port and the discharge port of the port plate 8, the swash plate 7 moves to a small inclination angle position at which a small discharge capacity is obtained. Even if the piston 5 rises and sudden compression occurs due to tilting, the check valve 42 opens when the pressure exceeds a predetermined pressure, and the hydraulic oil in the bore chamber 9 passes through the relief oil passage 41. And discharged to the discharge oil passage 21.

By such an operation of the check valve 42, the danger that the bore chamber 9 may generate an abnormal pressure that may cause damage to the cylinder block 3 is avoided. When the pressure in the bore chamber 9 falls below a predetermined value, the check valve 42 is immediately closed, and the pump driving with a small discharge capacity is continued without any trouble by the swash plate 7 having a small inclination angle.

DESCRIPTION OF SYMBOLS 1,100: Two capacity | capacitance variable piston pump 2 for rotational speed control, 102: Rotating shaft 3, 103: Cylinder block 4, 104: Bore 5, 105: Piston 6, 106: Piston end shoe 7, 107: Swash plate 8 108: Port plate 9, 109: Bore chamber 10, 110: Casing body 11, 111: Pump chamber 12, 112: Kidney port 113: Suction port 114: Discharge port 115: Escape groove 16, 116: Spring mechanism 17, 117 : Operating piston 118: Electromagnetic switching valve 20, 120: Casing cover 21, 121: Discharge oil passage 30: Abnormal pressure avoidance hydraulic circuit 31: Discharge passage 31X: Port plate through hole 32: Safety valve 40: Abnormal pressure avoidance hydraulic circuit 41: Relief oil passage 41X: Port plate through hole 42: Check valve

Claims

A rotating shaft that is driven to rotate by a motor, a cylinder block that rotates integrally with the rotating shaft, a plurality of bores formed in the cylinder block in parallel with the rotating shaft, and accommodated in each bore A single unit structure in a pump chamber comprising an inner space of the same casing. As each of the pistons reciprocates within the bore with a stroke corresponding to the inclination angle of the swash plate as the rotating shaft and the cylinder block rotate, the bore is formed in the bore chamber formed by the bore and the piston. The working oil is sucked from the suction oil passage formed inside the casing through the suction port of the port plate in which the cylinder block is slidably contacted, and the port pre- In through the city of discharge port speed control variable piston pump that discharges hydraulic oil to formed within the discharge passage of the casing,
When the pressure in the bore chamber located between the suction port and the discharge port of the port plate exceeds a predetermined pressure, an abnormal pressure avoiding hydraulic circuit that releases the hydraulic oil in the bore chamber to the outside of the bore chamber, A variable piston pump for controlling the rotational speed, wherein the variable piston pump is incorporated in the unit structure in the same casing.
2. The rotation according to claim 1, wherein the abnormal pressure avoiding hydraulic circuit includes a safety valve that discharges hydraulic oil in a bore chamber located between the suction port and the discharge port into the pump chamber. Variable piston pump for number control.
The abnormal pressure avoiding hydraulic circuit includes a relief oil passage that communicates a bore chamber located between the suction port and the discharge port and the discharge oil passage through a check valve. The variable piston pump for rotational speed control according to claim 1.