WO1996032587A1

WO1996032587A1 - Apparatus for controlling swash-plate pump and motor

Info

Publication number: WO1996032587A1
Application number: PCT/JP1996/001006
Authority: WO
Inventors: Kenji Morino; Yosuke Oda; Seita Hayashi
Original assignee: Komatsu Ltd.
Priority date: 1995-04-12
Filing date: 1996-04-11
Publication date: 1996-10-17
Also published as: JP3672046B2; EP0821163A4; KR960038112A; EP0821163A1; JPH08284806A

Abstract

An apparatus for controlling swash-plate pumps and motors, provided with a piston (40) fitted slidably in a cylinder bore (31) formed in a housing (20), a large-diameter pressure receiving chamber (43) and a small-diameter pressure receiving chamber (44) defined on both end sides of the piston and permitting the piston to be moved in one direction and in the other by a pressure oil in these chambers, a spool (47) slidably fitted in a spool bore (45) formed in an axial core portion of the piston, a first port (58), a second port (65) and a drain port (66) which are provided between the piston and spool and adapted to be put in a communicating state and shut-off state in accordance with the relative movements of the piston and spool, a third pressure receiving chamber (54) defined on one end side of the spool and adapted to move the spool in one direction by a pressure oil therein, and a spring (74) urging the piston and spool in the other direction, the piston and a swash-plate (4) being connected together so that, when the piston is moved, a tilt angle of the swash-plate varies, the small-diameter pressure receiving chamber communicating with the swash-plate type pump or a primary port (26) of a motor, the first port communicating with the small-diameter chamber and third pressure chamber, the second port communicating with the large-diameter pressure receiving chamber, the drain port communicating with a tank (18) via the interior of the housing, the first and second ports being shut off from each other with the second port and drain port communicating with each other when the piston is moved in one direction relatively to the spool, the first and second ports communicating with each other with the second port and drain port shut off from each other when the piston is moved in the other direction relatively to the spool.

Description

Description Swash plate pump and motor swash plate control device

The present invention relates to a swash plate pump and a swash plate control device for a motor that control the tilt angle of the swash plate of the swash plate pump and the motor so that the input torque and the output torque are substantially constant. Dizziness technology

A swash plate pump is designed to increase or decrease the discharge amount (capacity) per rotation by tilting the swash plate. The capacity increases as the tilt angle of the swash plate increases and as the tilt angle decreases, the displacement increases. The input torque of the swash plate type pump becomes the pressure X capacity of the discharge pressure oil.

The swash plate type motor tilts the swash plate to increase or decrease the inflow amount (capacity) per rotation. The capacity increases as the tilt angle of the swash plate increases, and decreases as the tilt angle of the swash plate decreases. Then, the output torque of the swash plate type motor becomes the pressure X capacity of the supply pressure oil.

In order to make the input torque of the swash plate pump constant, the tilt angle of the swash plate may be controlled by the pressure of the discharge pressure oil. In this way, a device for controlling the tilt angle of the swash plate is provided. For example, Japanese Patent Laid-Open No. 52-

The one disclosed in Japanese Patent Application Laid-Open No. 9-802 is known.

This is achieved by installing a first pressing device and a servo valve in the housing, and pushing the swash plate in the direction of decreasing the tilt angle with the first pressing device, and pressing the swash plate in the direction of increasing the tilt angle with the servo valve. , The servo valve includes a housing and a housing

A piston slidably inserted into the first hole, a follower slidably inserted into the second hole of the housing, and a slidably inserted into the follower sleeve The servo spool valve includes a load piston disposed coaxially with the servo spool valve, a spring for pressing the servo spool valve, and the like. The swash plate tilt angle is controlled by the first pressing device and the servo valve so that the swash plate tilt angle becomes an angle commensurate with the pump discharge pressure.

However, the swash plate control device described above includes a first pressing device and a servo valve, and the servo valve includes a housing, a piston, a follow-up sleeve, a servo spool valve, a load piston, a spring, and the like. Since it is composed of many parts, the number of parts is large and the assembling work is not only troublesome, but also expensive, and the entire servo valve becomes large and the mounting space for the housing becomes large. There was a problem that the pump became large.

Accordingly, in view of the above problems, the present invention has a small number of parts, facilitates assembling work, is inexpensive, and has a small mounting space for a swash plate. It is an object of the present invention to provide a swash plate type pump and a swash plate control device for a motor that can reduce the size of a pump and a motor.

Disclosure of the invention

In order to achieve the above first object, a swash plate type pump and a swash plate control device for a motor according to the present invention include:

A housing; a cylinder hole formed in the housing; Pistons slidably fitted in the cylinder holes, and the pistons are formed on both ends of the pistons and pressurized in one direction and the other direction by the internal pressure oil. A large-diameter pressure receiving chamber and a small-diameter pressure receiving chamber to be pushed; a spool hole formed in a shaft core of the piston; a spool movably inserted into the spool hole; A first port, a second port, and a drain port which are provided over the spool and which are communicated and blocked by relative movement between the piston and the spool; A pressure receiving chamber configured to push the spool in one direction with pressurized oil therein, and a spring for biasing the piston and the spool in the other direction.

The piston is connected to a swash plate type pump or motor swash plate so that the tilt angle of the swash plate changes when the piston moves, and the small-diameter pressure receiving chamber is connected to the main body of the swash plate type pump or motor. The first port communicates with the small-diameter pressure receiving chamber and the other pressure receiving chamber, the second port communicates with the large-diameter pressure receiving chamber, and the drain port communicates with the inside of the housing. And communicate with the tank,

When the piston moves in one direction relative to the spool, the connection between the first port and the second port is cut off, and the second port and the drain port are disconnected. Communicates,

When the piston moves in the other direction relative to the spool, the first port and the second port communicate with each other, and a gap between the second port and the drain port is formed. Is to be cut off.

According to the above configuration, the piston is inserted into the cylinder hole of the housing. In addition, a basic structure is adopted in which a spool is inserted into the piston and a spring is provided to urge the spool, so that the number of parts is reduced, making assembly work easy and inexpensive. In addition, since the entire device becomes smaller and the space for mounting the housing becomes smaller, the swash plate type pump and motor can be made smaller.

In the above dicing, it is preferable that a bolt is screwed into the housing, fastened and fixed with a lock nut, and the spring is interposed between the bolt, the piston and the spool.

According to this configuration, the mounting load of the spring can be adjusted by tightening and loosening the bolt from the outside of the housing, and the input torque of the swash plate pump or the output torque of the swash plate motor is set. Can be changed manually from outside.

Further, in the above configuration, the spool has a stepped shape having a large-diameter portion and a small-diameter portion, and the small-diameter portion is protruded into the small-diameter pressure receiving chamber. The large diameter portion may be fitted to a shaft core to form an input torque changing pressure receiving chamber, and external pressure may be supplied to the input torque changing pressure receiving chamber.

According to this configuration, by changing the pressure of the pressure oil supplied to the pressure receiving chamber, the force for pushing the spool in one direction can be adjusted, whereby the input torque of the swash plate pump or the output torque of the swash plate motor can be adjusted. Can be changed by an external oil pressure.

Further, in the above configuration, it is preferable that the other pressure receiving chamber is formed between the plug and the large diameter portion of the spool. Drawing! # The invention will be better understood from the following detailed description and the accompanying drawings illustrating an embodiment of the invention. The embodiments shown in the accompanying drawings are not intended to specify the invention, but merely to facilitate explanation and understanding.

In the figure,

FIG. 1 is an explanatory view of the operation principle showing an embodiment of a swash plate type pump and motor swash plate control device according to the present invention.

FIG. 2 is a cross-sectional view of the swash plate pump of the above embodiment.

FIG. 3 is a cross-sectional view taken along the line Π-m of FIG.

FIG. 4 is a partially enlarged sectional view of FIG.

FIG. 5 is a sectional view taken along line VV of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a swash plate control apparatus for a swash plate pump and a motor according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

First, the principle of the swash plate type pump and motor swash plate control device will be described.

(Construction)

As shown in FIG. 1, a swash plate pump 2 and a fixed displacement pump 3 are driven by an engine 1. The swash plate 4 of the swash plate pump 2 is tilted by the piston 6 of the cylinder 5 through the link 16, and the piston 6 is tilted by the oil in the large-diameter pressure receiving chamber 7 to have a small tilt angle. And the spring 9 presses the oil in the small-diameter pressure receiving chamber 8 in the large tilt direction.

The large-diameter pressure receiving chamber 7 is connected to the tank 18 and the pump discharge by the switching valve 10. The small-diameter pressure receiving chamber 8 is always in contact with the pump discharge path 11 of the swash plate type pump 2. Then, the switching valve 10 is pushed to the drain position A by the spring 12, and is pushed to the supply position B by the pressure oil of the first pressure receiving portion 13 and the pressure oil of the second pressure receiving portion 14.

The first pressure receiving section 13 is connected to the pump discharge path 11 of the swash plate type pump 2 via the small-diameter pressure receiving chamber 8, and the second pressure receiving section 14 is connected to the discharge path 15 of the fixed displacement pump 3. ing. The spring 12 of the switching valve 10 is connected to the piston 6 via a link 16 so that the movement of the piston 6 is fed back to the switching valve 10. It is made to be clicked.

(motion)

When the pressure of the discharge pressure oil (hereinafter referred to as discharge pressure) of the swash plate pump 2 increases in the state shown in FIG. 1, the switching valve 10 is pushed to the supply position B, and the discharge pressure oil of the swash plate pump 2 increases. The piston 6 is also supplied to the radial pressure receiving chamber 7, so that the piston 6 is pushed in the small tilt angle direction by the pressure receiving area difference between the large diameter pressure receiving chamber 7 side and the small diameter pressure receiving chamber side, and the swash plate 4 tilts. As the angle becomes smaller, the capacity of the swash plate type pump 2 becomes smaller.

Then, along with the movement of the piston 6, the link 16 moves rightward in FIG. 1 to increase the spring load of the spring 12 and push the switching valve 10 to the drain position A. Since the large-diameter pressure receiving chamber 7 communicates with the tank 18, the piston 6 is displaced by the discharge pressure of the swash plate type pump 2 supplied to the small-diameter pressure receiving chamber 8 and the tilting angle by the spring 9. As a result, the tilt angle of the swash plate 4 increases, and the capacity of the swash plate pump 2 increases. Thus, the above operation is repeated, and the swash plate 4 is changed to discharge pressure and capacity. Is controlled to a tilt angle at which the product of (input torque) becomes substantially constant.

Here, since the switching valve 10 is pushed to the supply position B even with the pressure of the second pressure receiving portion 14, the input torque can be set to an arbitrary value by changing the pressure of the second pressure receiving portion 14. Can be set.

Next, the specific structure of the swash plate control device will be described.

(Structure of swash plate type pump 2)

As shown in FIG. 2, a shaft 22 is rotatably supported in a housing 20, and a cylinder block 21 is fixed to the shaft 22. Then, the tips of the screws 24 slidably fitted in the plurality of cylinder holes 23 parallel to the axis of the cylinder block 21 are connected to the swash plate 4 via the screws 19. Slidable in the circumferential direction along the front surface 4a of the cylinder block, and the piston chamber 25 in the cylinder hole 23 becomes the main chamber every time the cylinder block 21 rotates approximately 180 degrees. Port 26 is alternately connected to a drain port (not shown). As a result, oil is sucked into the piston chamber 25 while the cylinder block 21 rotates approximately 180 degrees, and the piston chamber 25 rotates during the remaining rotation of 180 degrees. The oil inside is pressurized and discharged from main port 26.

In addition, the back surface 4 b of the swash plate 4 is a part of a cylindrical surface that is orthogonal to the axis 22 in FIG. 2 and is centered on an axis included in the paper surface, and coincides with the back surface 4 b of the housing 20. The swash plate 4 is supported swingably along a guide portion 27 which forms a part of a cylindrical surface, and a slider 28 connected to the swash plate 4 is moved by a control device 29 in a direction orthogonal to the paper surface. Then, the swash plate 4 rotates about the axis of the cylindrical surface to change its tilt angle.

(Specific structure of control device 29) As shown in FIGS. 3, 4, and 5, the housing 20 is provided with a large-diameter first screw hole 30, a cylinder hole 31 and a small-diameter second screw hole 32 around the same axis. A first stopper 33 is screwed into the first screw hole 30 and fixed with a lock nut 34, and a second stopper is inserted into the second screw hole 32. Locked nut with screw 3

Fixed at 3 6

The cylinder hole 31 is a stepped hole composed of a large-diameter cylinder hole 37 and a small-diameter cylinder hole 38, and a part of the peripheral wall of the large-diameter cylinder hole 37 is a notch 3. The slider 28 is connected to the swash plate 4 in the notch 39, which is open in the housing 20 at 9.

A piston 40 is inserted into the cylinder hole 31, and the piston 40 is inserted into the large-diameter cylinder hole 37 and the large-diameter piston 41 and the small-diameter cylinder hole. It is formed in a stepped shape consisting of a small-diameter piston 42 fitted in 38, and a large-diameter pressure receiving chamber 4 is provided between the large-diameter piston 41 and the first stopper 33. 3 is formed, and a small-diameter pressure receiving chamber 44 is formed between the small-diameter piston 42 and the second flange 35.

A spool hole 45 is formed in the shaft core of the large-diameter piston 41, and a large-diameter hole 46 is formed in the shaft core of the small-diameter piston 42. The spool hole 45 is a stepped hole, and the stepped spool 47 is fitted therein. A rod 50 provided on a plug 49 inserted into the left end of the large-diameter piston 41 is fitted to the axis of the large-diameter portion 48 of the spool 47 to form a first pressure-receiving chamber. The first pressure receiving chamber 51 communicates with the annular groove 52 of the large diameter portion 48. Also plug

49 is secured by a screw plug 53 screwed to the large-diameter piston 41, and a second pressure receiving portion is provided between the plug 49 and the end face of the large-diameter portion 48. Chamber 54 is formed.

An axial hole 55 is formed in the axial center of the spool 47, and one end of the hole 55 opens into the end face of the small diameter portion 56 of the spool 47 to form the small diameter pressure receiving chamber 44. The other end of the hole 55 communicates with a first port 58 formed of an annular groove formed on the outer peripheral surface of the large diameter portion 48 by a radial hole 57. As shown in FIGS. 4 and 5, the first port 58 has a first small-diameter hole 59 formed in the large-diameter piston 41 in the radial direction, and a slit-shaped recess 6 3. , Through the second small-diameter hole 60, to the second pressure receiving chamber 54, and the annular concave portion 52 is formed through the third small-diameter hole 61 in the radial direction and the slit-shaped concave portion 62 through the inlet port 6. 4 in communication. A second port 65 composed of an annular recess and a drain port 66 composed of a small hole are formed in the large diameter portion of the spool hole 45. Then, the second port 65 communicates with the large-diameter pressure receiving chamber 43 via a fourth small-diameter hole 67 and a fifth small-diameter hole 68 formed in the housing 20, and the drain port 66 is connected to the second port 65. It communicates with the inside of the housing 20 (tank). The small-diameter pressure receiving chamber 44 communicates with the main port 26 through an oil hole 69 formed in the housing 20.

A bolt 70 is combined with the second flange 35 and fixed with a nut 71. A spring 74 is provided between the movable seat 72 and the receiving seat 72 provided at the tip of the bolt 70, and the movable receiving seat 73 is formed by the elasticity of the spring 74. The spool 47 is pressed against the end of the small diameter portion 56 of the spool 47 to the left in the drawing.

A cutout recess 75 is formed in the large-diameter piston 41, and the slider 28 is fitted and connected to the cutout recess 75. The piston 40 and the swash plate 4 are connected.

Next, the operation of the present embodiment will be described.

In the initial state where the pressure oil is not supplied to the small-diameter pressure receiving chamber 44, the spool 47 and the piston 40 are pushed to the left by the spring 74 so that the end face of the large-diameter piston 41 is in the first position. It comes into contact with the collar 33, which cuts off the connection between the first port 58 and the second port 65, and connects the second port 65 to the drain port 66. The large-diameter pressure receiving chamber 43 communicates with the tank.

That is, the switching valve 10 shown in FIG. 1 is in the drain position A.

In the above-described state, when the pressure oil (the discharge pressure oil at the pressure P 1) of the main port 26 of the swash plate pump 2 flows into the small-diameter pressure receiving chamber 44 from the oil hole 69, the pressure oil flows into the hole 55, It flows into the first port 58 through the hole 57, and further flows into the second pressure receiving chamber 54 through the first small-diameter hole 59, the concave portion 63, and the second small-diameter hole 60. To charge.

At this time, the spool 47 is pushed leftward by the pressure P1 acting on the end face of the small diameter section 56, and pushed rightward by the pressure P1 acting on the end face of the large diameter section 48. Here, assuming that the diameter of the small diameter portion 56 is dl, the diameter of the rod 50 is d2, and the diameter of the large diameter portion 48 is d3 (d3>d2> dl), the spool 47 has 7Γ / ^{4 (d 3 2 - d 2} 2 - d I 2) x P 1 thrust pressurized Erareru rightward.

When the thrust becomes larger than the mounting load of the spring 47, the spool 47 is pushed rightward, and the first port 58 and the second port 65 communicate with each other. 6 5 and the drain port 66 are shut off, and the hydraulic oil of the first port 58 is supplied with the second port 65, the third small-diameter hole 67, It flows into the large-diameter pressure receiving chamber 43 through the fourth small-diameter hole 68. In other words, the switching valve 10 in FIG. 1 is in the supply position B, and the discharge pressure of the swash plate pump 2 acts on the large-diameter pressure receiving chamber 43.

When the pressure oil flows into the large-diameter pressure receiving chamber 43, the piston 40 is pushed rightward due to the pressure difference caused by the pressure-receiving area difference between the large-diameter pressure receiving chamber 43 and the small-diameter pressure receiving chamber 44. As a result, the swash plate 4 is tilted in the small tilt angle direction via the slider 28.

At this time, even if the piston 40 moves to the right, the force to move the spool 47 to the right balances the mounting load of the spring 74, so the spool 47 does not move and the piston Pin 40 moves relative to spool 47.

When the piston 40 moves to the right by a predetermined distance, the first port 58 and the second port 65 are shut off, and the second port 65 communicates with the drain port 66 to form a large-diameter port. The pressurized oil in the pressure receiving chamber 43 flows out of the drain port 66 into the tank. Then, the piston 40 moves to the left due to the pressure in the small-diameter pressure receiving chamber 44, so that the first port 58 and the second port 65 communicate with each other, and the second port 65 is drained. The connection with the port 6 6 is shut off.

By repeating the above operation, the piston 40 stops at the position corresponding to the discharge pressure, and as a result, the tilt angle of the swash plate 4, that is, the capacity of the swash plate pump 2, becomes a value corresponding to the discharge pressure. Therefore, the input torque becomes substantially constant with the set value.

In the above description, the description of the action of the pressure oil flowing into the first pressure receiving chamber 51 is omitted, but the first pressure receiving chamber 51 corresponds to the second pressure receiving section 14 in FIG. In the first pressure receiving chamber 51. The input torque value can be changed by pushing the spool 47 rightward with hydraulic pressure.

Also, by loosening the lock nut 71 and tightening the bolt 70, the load on the spring 74 can be changed to change the set value of the input torque.

Also, if the lock nuts 34 and 36 are loosened to move the first stopper 33 and the second stopper 35 forward and backward to change their positions, the minimum tilt angle of the swash plate 4 and The maximum tilt angle can be changed.

Although the above embodiment relates to a swash plate type pump, the configuration of the swash plate type control device according to the present invention is exactly the same as that of the swash plate type motor. Since the oil is supplied, the supplied pressure oil may be introduced into the small-diameter pressure receiving chamber 44 through the main port 26 and the oil hole 69.

As described above, according to the swash plate pump and the swash plate control device for the motor according to the present invention, the swash plate tilt angle becomes an angle corresponding to the oil pressure of the main port 26, and thus the swash plate pump The input torque or the output torque of the swash plate motor becomes almost constant.

In addition, the swash plate control device according to the present invention has the piston 40 inserted into the cylinder hole 31 of the housing 20, the spool 47 inserted into the piston 40, and the spool 47. Since the basic structure with springs 74 is used, the number of parts is reduced, making assembly work easier and less expensive. Swash plate pump and motor can be reduced in size.

Further, according to the swash plate control device of the present invention, the housing 20 The mounting load of the spring 74 can be adjusted by externally tightening or loosening the bolt 70, and the set value of the input torque of the swash plate pump or the output torque of the swash plate motor can be manually operated from the outside. Can be changed with.

Further, according to the swash plate control device according to the present invention, the force for pushing the spool 47 in one direction can be adjusted by changing the pressure of the pressure oil supplied to the pressure receiving chamber 51, and thereby the swash plate type The set value of the input torque of the pump or the output torque of the swash plate type motor can be changed by external hydraulic pressure.

Although the present invention has been described with reference to exemplary embodiments, various modifications, omissions, and additions can be made to the disclosed embodiments without departing from the spirit and scope of the present invention. Is obvious to those skilled in the art. Therefore, the present invention should not be limited to the above-described embodiments, but should be understood to include the scope defined by the elements recited in the claims and their equivalents.

Claims

The scope of the claims

1. A housing, a cylinder hole formed in the housing, a piston slidably fitted in the cylinder hole, and a surface formed on both ends of the piston. A large-diameter pressure receiving chamber and a small-diameter pressure receiving chamber for pushing the piston in one direction and the other direction, respectively, with pressurized oil inside each; a spool hole formed in a shaft core of the piston; A spool slidably fitted in the spool hole, and a spool which is provided directly to the piston and the spool and is communicated and cut off by a relative movement between the piston and the spool. A first port, a second port, and a drain port; another pressure receiving chamber defined at one end of the spool, which presses the spool in one direction with pressurized oil therein; And a spring that urges the spool in the other direction Offering the door,

The piston is connected to a swash plate type pump or motor swash plate so that when the piston moves, the tilt angle of the swash plate changes, and the small-diameter pressure receiving chamber is connected to a main port of the swash plate type pump or motor. The first port communicates with the small-diameter pressure receiving chamber and the other pressure receiving chamber, the second port communicates with the large-diameter pressure receiving chamber, and the drain port passes through the inside of the housing. It is connected to the tank,

When the piston moves in one direction relative to the spool, the first port and the second port are shut off, and the second port and the drain port are shut off. Communicates with

When the piston moves in the other direction relative to the spool, the first port communicates with the second port, and the second port communicates with the drain port. Was cut off, Swash plate type pump and motor swash plate control device.

2. The slant according to claim 1, wherein a bolt is screwed into the housing, fastened and fixed with a lock nut, and the spring is interposed between the bolt, the piston, and the spool. Swash plate control device for plate pumps and motors.

3. The spool has a stepped shape having a large-diameter portion and a small-diameter portion, and the small-diameter portion is protruded into the small-diameter pressure receiving chamber, and a plug rod fixed to the piston is attached to the large-diameter portion of the spool. The swash plate pump according to claim 1 or 2, wherein the pressure receiving chamber for input torque change is defined by being fitted to the shaft core, and external pressure is supplied to the pressure receiving chamber for input torque change. And a motor swash plate control device.

4. The swash plate pump and motor according to claim 1, wherein the other pressure receiving chamber is formed between the plug and a large diameter portion of the spool.