JPH10238457A - Bent axis type axial piston pump/motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any abrasion or seizure at a spherical slide face or leakage of lubricant from a high pressure region to a low pressure region by disposing a seat slidable in a longitudinal direction of a hole with respect to a center hole formed at a cylinder block, and forming a contact portion between a center shaft and the seat into a spherical shape, which provides free oscillation. SOLUTION: In a bent axis type piston motor, a plurality of piston assemblies 36 are disposed at equal intervals in a flange 31a formed at one end of a drive shaft 31, and a cylinder block 42 is disposed in such a manner as to be freely oscillated in a vertical direction together with a center shaft 35. In this case, a seat 46 and a spring 47 are housed inside a center hole 42c formed at the cylinder block. A lubricating groove is formed at the outer-diameter portion of the seat 46, and further, a passage, through which lubricant flows, is formed between the center shaft 35 and the seat 46 at the inner diameter portion. One end of the seat 45 is formed into a spherical recessed shape, so as to be brought into spherical contact with the spherical projection of the center shaft 35 by resiliency of the spring 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagonal axial piston pump / motor, and more particularly to a rotary shaft of a cylinder block having a center of a rotary shaft on a drive shaft side and a center of a spherical sliding surface on a valve plate side. It relates to a mechanism for centering.

[0002]

2. Description of the Related Art A cylinder block is rotated via a drive shaft by the power of a drive source, and reciprocates a piston in a cylinder to suck oil from a tank and discharge high-pressure oil to convert mechanical energy into fluid energy. Converting, so-called piston pumps are known. Also,
A so-called piston motor that converts fluid energy into mechanical energy by rotating a cylinder block and a drive shaft by guiding high-pressure oil from a pump to a cylinder and reciprocating a piston is also known.

Hitherto, Japanese Patent Publication No. 59-4553 is known as this type of piston pump and piston motor. According to the publication, as shown in FIG. 3, a hole 51a is formed in the cylinder block rotation center axis A of the cylindrical cylinder block 51, and one of the cylindrical portions 52a of the center shaft 52 is formed in the hole 51a. The ball 52b of the center shaft 52 is integrally formed with one cylindrical portion 52a, and the ball 52b is located at the center of the ball seat 53a of the rotation axis B of the drive shaft 53. Is kept. The illustrated right end portion 51b of the cylinder block 51 is formed as a concave spherical surface, and the concave spherical surface is a convex spherical surface 54a of the valve plate 54.
, Receiving the pressing force of the spring 55. The opposite side of the valve plate 54 is also formed on the convex cylindrical surface 54b, and the convex cylindrical surface 54b abuts on the cover 56 under the pressing force of the spring 55. The center shaft 52 is connected to the valve plate 5
4, and the center axis of the cylinder block 51 is regulated such that the center point between the concave spherical surface of the cylinder block 51 and the convex spherical surface 54a of the valve plate 54 coincides with each other. ing. That is, the cylinder block rotation center axis A is set on a line connecting the center position of the ball seat 53a of the drive shaft rotation axis B and the ball center position of the spherical sliding surface between the valve plate 54 and the cylinder block 51. I do.

In Japanese Utility Model Laid-Open Publication No. Sho 50-64856, as shown in FIG.
However, a drive shaft rotation shaft 64 is formed by a center ball 63, one of which is incorporated at the tip of the center shaft 62.
At the center position C of the ball seat 64a. In the middle of the center shaft 62, a concave spherical base 66 incorporated in the cylinder block 61 so that the cylinder block 61 can abut on the valve plate 65 in a plane.
And a hemispherical receiver 67 having a convex spherical shape whose end face abuts on a flange 62a integrally formed with the center shaft 62. The cylinder block rotation center axis D is formed by relatively moving on both spherical surfaces. . Further, in the present embodiment, a balance piston 68 is disposed between the center shaft 62 and the valve plate 65, and the hydraulic pressure acting on the port 65a is applied to the balance piston 68 through the hole 65b to reduce the oil pressure on the center shaft. The pressing force (surface pressure) on the valve plate 65 is transmitted to the cylinder block 61 via 62.

[0005]

However, the market is
Higher pressures and higher speeds are being developed in the hope that smaller and lighter piston pumps and motors will provide the required hydraulic power. Also, as can be seen from the example of high-speed traveling of a hydraulic excavator, the speed of the traveling drive piston motor has been increased (increased rotational speed).
In the direction of However, in order to increase the pressure and speed, it is necessary to solve the problems caused by these. The problem with high pressure is that the leakage from the high pressure range to the low pressure range, such as the sliding surface between the cylinder block and the valve plate, where seal members cannot be used in the components of piston pumps and motors, has the problem of processing accuracy of the components. Unless assembling accuracy is improved, it will increase steadily, and volume efficiency (in the case of a pump, the ratio between the actual discharge amount and the theoretical discharge amount including leakage, etc., for a motor, the ratio between the theoretical inflow amount and the actual inflow amount) will decrease. That is. In addition, since the sliding surfaces of both parts come into contact at high speed in the above-described example, the processing accuracy and the assembly accuracy of the components of the piston pump and the motor, that is, the connection between the cylinder block and the valve block is also problematic. It is considered that unless the displacement of the center position of the sliding surface (hereinafter referred to as misalignment) is improved, galling and seizure of both parts due to local contact cannot be avoided.

For example, with respect to a certain capacity and the type of Japanese Patent Publication No. 59-4553 shown in FIG. 3 or the oblique shaft type piston motor shown in FIG. 1, the machining accuracy of several types of parts constituting the piston motor is taken into consideration. I tried to estimate the amount of misalignment. Table 1 shows the spherical center axes M and N of the spherical sliding surfaces of the cylinder block 51 and the valve plate 54.
The total value is the amount of misalignment ΔA between the center of the ball 52 b of the center shaft 52 and the center of the ball seat 53 a of the drive shaft rotating shaft 53.

[0007]

[Table 1]

Actually, the ball seat 53 of the drive shaft 53
a and the center of the ball 52b of the center shaft 52 are aligned so that the spherical sliding surfaces of the cylinder block 51 and the valve plate 54 having the same radius of curvature are mutually spherical center axes M , N are displaced and galling and seizing occur due to leakage from the spherical sliding surface of the cylinder block 51 and the valve plate 54 and local contact.

A conventional technique for solving this problem is to increase the gap between the cylinder block center hole 51a in which the center shaft 52 is incorporated and the outer diameter of the center shaft 52 in FIG. ing. However, in this type, the ball seat 53a of the drive shaft 53
And the distance (Wa) between the cylindrical portion 52a of the center shaft 52 inserted into the hole 51a of the cylinder block 51 is short, and the cylindrical portion 52a is
Since it is directly inserted into the hole 1a with a distance (Wb) in the longitudinal direction of the hole, a twice as large gap is required to escape the misalignment. According to a trial calculation, the diameter gap becomes 70 μm and the rotor rotates while being swung largely in the diameter direction. As a result, the spherical center axes M and N of the spherical sliding surface of the cylinder block 51 and the valve plate 54 are shifted, and the cylinder is shifted. A gap is formed between the block 51 and the valve plate 54, and the performance decreases due to leakage.
Local contact between the valve plate 54 and the valve plate 54 causes galling. For example, rated capacity 160 cc / rev,
When rotated at a pressure of 350 kg / cm ² and a rotation speed of 5000 rpm, the cylinder block 51 and the valve plate 5 are rotated.
4 and the outer diameters of the cylinder block center hole 51a and the center shaft 52 are seized in a short time. In addition, the oil film thickness changes due to the pressure generated in the gap between the cylinder block 51 and the valve plate 54, and the change in the oil film thickness causes the cylinder block 51 to vibrate in the left-right direction as shown in the drawing. There is a problem that the outer diameter of 52 is seized.

Further, in the form of Japanese Utility Model Laid-Open Publication No. Sho 50-64856, the misalignment of the cylinder block 61 is caused by a concave spherical base 66 incorporated in the cylinder block 61,
The hemispherical receiver 67 having a convex spherical shape built into the center shaft 62 is in contact with the spherical surface, but the cylinder block 61 and the valve plate 65 are in contact with each other in a plane and are slid. The misalignment of the center ball 63 with respect to the seat 64a becomes the misalignment of the cylinder block 61 as it is. For this reason, the cylinder block 61
Is rotated while being swung largely in the diameter direction. As a result, when rotated at high speed, the cylinder block 6 is rotated.
1 and the valve plate 65 are rotated with their cores largely displaced, so that seizure occurs. Alternatively, the cylinder block 61 rotates while being swung largely in the diameter direction, and the center shaft 62 is broken. Also,
Because the center shaft 62 swings in the longitudinal direction of the shaft,
It is necessary to divide the center shaft 62 and the center ball 63, and the variation at the time of assembling increases, resulting in an increase in misalignment. Further, a balance piston 68 is provided between the center shaft 62 and the valve plate 65, and the center shaft 62, the base 6
Since the cylinder block 61 and the valve plate 65 are brought into contact with each other via the hemispherical receiver 6 and the hemispherical receiver 67, the contact surface pressure between the base 66 and the hemispherical receiver 67 increases. There's a problem.

The present invention focuses on the above-mentioned conventional problems, and relates to an oblique-axis axial piston pump / motor. In particular, the present invention relates to a spherical sliding surface between a cylinder block and a valve plate for high pressure and high speed. It is an object of the present invention to provide a centering mechanism capable of preventing galling, seizure, and leakage from a high pressure range to a low pressure range.

[0012]

In order to achieve the above object, an oblique axial piston pump / motor according to the present invention comprises a drive shaft and a cylinder via a piston assembly comprising a piston and a rod. In the oblique-axis axial piston pump / motor that connects the block and the cylinder block and the valve plate have a spherical shape, a spring that generates a force that presses the cylinder block against the valve plate and a hole in the center of the cylinder block On the other hand, the seat slidable in the hole longitudinal direction, the center shaft, and the contact portion of the seat are formed into a swingable spherical shape, and the seat outer diameter and the cylinder block center hole are formed as small tightly-closed gaps, A means to lubricate between the seat outer diameter and the cylinder block center hole is provided. It is characterized in. According to the above configuration, a sheet slidable in the longitudinal direction of the hole with respect to the center hole of the cylinder block is provided, and a contact portion between the center shaft and the sheet is formed into a spherical shape capable of swinging. Since it can be absorbed by the swinging action of the contact portion and the sliding action in the longitudinal direction of the hole of the seat, there is no misalignment between the spherical sliding surfaces of the cylinder block and the valve plate. Therefore, galling and seizure on the spherical sliding surface and leakage from the high pressure range to the low pressure range can be prevented. Moreover, in Japanese Utility Model Laid-Open No. 50-64856, the center shaft swings in the longitudinal direction of the shaft. On the other hand, in the present invention, the contact portion to the seat is formed into a swingable spherical shape and the drive shaft is Since the center shaft abuts on the drive shaft at a certain position, there is no gap, and the contact pressure between the center shaft and the seat becomes constant. Easy to align.

Further, since lubricating means is provided between the outer diameter of the seat and the center hole of the cylinder block, the gap between the outer diameter of the seat and the center hole of the cylinder block can be reduced.
Thereby, the misalignment of the cylinder block can be reduced, and the swinging operation and the sliding action for alignment can be performed smoothly, so that the speed and the pressure can be further increased. Also, since the gap between the cylinder block center hole and the seat outer diameter is lubricated, even if the gap between the cylinder block center hole and the seat outer diameter is reduced, the oil film thickness of the gap between the cylinder block and the valve plate can be reduced. Seizure due to vibration of the cylinder block due to the change does not occur.

As described above, even if the misalignment between the components of the piston pump and the motor accumulates, the seat can be slid along the center hole of the cylinder block and the contact portion between the center shaft and the seat can be swung. Because of the spherical shape, the spherical contact portion can slide while swinging, and the spherical sliding surface between the cylinder block and the valve plate is aligned. Since there is no need to increase the gap between the center shaft outer diameter and the cylinder block center hole as in the conventional case, the cylinder block does not rotate while being swung largely in the diameter direction,
For even higher speed and higher pressure, galling of the spherical sliding surface,
Seizure and leakage from a high pressure range to a low pressure range can be prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a piston pump and a motor according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example of a diagonal shaft type piston motor. A drive shaft 31 rotates while being supported by bearings 33 and 34 housed in a case 32. Case 32
Is provided with a drain port 32a. On one end side of the drive shaft 31, a flange portion 31a is integrally formed. A ball 35a formed integrally with the center shaft 35 on the rotation axis A of the drive shaft 31 is incorporated in the flange portion 31a.
It swings up and down with respect to one rotation axis A at a predetermined tilt angle.

A plurality of piston assemblies 36 are arranged on the flange 31a at equal intervals on the same circumference from the rotation axis A of the drive shaft 31. The piston assembly 36 includes a rod 37 and a piston 3
8 and are swingably connected. The spherical portion 37a at the other end of the rod 37 is
The first flange portion 31a is swingably attached to the first flange portion 31a. Thus, the piston 38 is swingably attached to the drive shaft 31 and the rod 37, respectively. The outer diameter of the other end of the piston 38 is inserted into a cylinder block 42, which will be described later, and seals high-pressure oil acting on the other end of the piston 38 with the outer circumference of the piston 38.

The cylindrical cylinder block 42 swings vertically with respect to the rotation axis A of the drive shaft 31 in accordance with the swinging of the center shaft 35 in the vertical direction by the tilt angle control device 60 described above. . Therefore, the cylinder block 42 rotates around the rotation axis B of the center shaft 35. One end surface of the cylinder block 42 is formed in a spherical shape, and the suction / discharge port 42
a, and the spherical surface slidably abuts the valve plate 43. On the other end surface side of the cylinder block 42, the same number of piston assemblies 36 as the number of the piston assemblies 36 mounted on the flange portion 31a and the cylinder block 4
A plurality of cylinder block holes 42b (hereinafter, referred to as cylinder holes 42b) are formed at equal intervals on the inner circumference of the cylinder 2. The cylinder hole 42b is connected to the spherical suction / discharge port 42a, and the cylinder hole 42b
, A piston assembly 36 is reciprocally inserted with a close gap. High-pressure oil from the suction / discharge port 42a acts on the end surface of the piston assembly 36. In the center of the cylinder block 42, a cylinder block center hole 42c through which the center shaft 35 passes is cut.

Ball 3 at one end of center shaft 35
5 a is incorporated in the flange portion 31 a, but the other end is supported by a bearing 44 of the valve plate 43. The valve plate 43 tilts the arc-shaped sliding surface 45 formed on the tilt angle control device 60 around the center C of the ball 35 a of the center shaft 35. The tilt angle is determined by the tilt of the rotation axis B of the cylinder block 42 with respect to the rotation axis A of the drive shaft 31.
Adjusted by 0. Now, when the tilt angle is adjusted to a small value, the cylinder block 42 approaches the rotation axis A of the drive shaft 31, so that the piston assembly 36 is further inserted into the cylinder block 42, and the stroke (difference in the amount of movement of the piston). Is also smaller. As a result, since the volume of space between the cylinder block 42 and the piston assembly 36 is reduced, the number of reciprocations of the piston assembly 36 per unit time increases when the tilt angle decreases for the same inflow, and the drive connected to the cylinder block 42 increases. The rotation speed of the shaft 31 increases. That is, the rotation speed is high, and the rotation speed is low when the tilt angle is large.

A seat 46 and a spring 47 are provided between the center shaft 35 and the cylinder block 42 and in the center hole 42c of the cylinder block. The contact state is maintained by the spherical sliding surface formed by. The suction / discharge port 42a of the cylinder block 42 is connected to an inlet for pressure oil of the valve plate 43 and an inlet / outlet port 43a which is a discharge oil outlet. FIG.
Is the cylinder block center hole 4 of the cylinder block 42.
An enlarged view of 2c and the sheet 46 is shown. Sheet 46
Has a groove 46a (diameter Da, width Ba) for lubrication in the outer diameter portion, and a passage 48 through which lubricating oil passes between the center shaft 35 and the seat 46 in the inner diameter portion. The seat 46 has a communication hole 46b connecting the groove 46a and the passage 48. For example, the communication hole 46b has four holes that are equally distributed in the circumferential direction. One end of the sheet 46 is formed in a spherical concave shape 46c, and is in spherical contact with the spherical convex shape 35b of the center shaft 35. In the conventional example shown in FIG. 3, when the misalignment between the piston pump / motorno components is maximum (0.35), the center shaft 52 is inserted into the hole 51a of the cylinder block 51 with a gap of about 0.070 mm. On the other hand, in the present invention, the seat 46 has a maximum diameter gap of about 0.
It is inserted at 026 mm concentrically.

Next, the operation will be described with reference to FIGS. In FIG. 1, high-pressure oil flows from the inlet / outlet port 43a of the valve plate 43 through the suction / discharge port 42a of the cylinder block 42 in a state where the cylinder block 42 is adjusted to a predetermined tilt angle by the tilt angle control device 60. It flows into the cylinder hole 42b. As a result, the piston assembly 3
6 is pushed out from the cylinder block 42, and the drive shaft 31 rotates with the cylinder block 42 by receiving a component in the rotation direction from the spherical portion 37 a at the tip of the rod 37. On the other hand, the piston assembly 36 of the cylinder block 42 is pushed into the cylinder hole 42b by the rotational force of the drive shaft 31, and the oil flows out to the low-pressure port (not shown) of the valve plate 43 through the port 43a. While repeating this state, the drive shaft 31
Rotates.

The operation of the piston motor is as described above.
Pressure oil leaks from between the cylinder block 42 and the valve plate 43 (Pa), and the leaked oil (Pa)
On the one hand, the bearing 44 of the valve plate 43 passes through the cylinder block central hole 42c and, on the other hand, the spherical contact Sa between the center shaft 35 and the seat 46, the inner diameter of the cylinder block 42 and the outer diameter of the seat 46. Is discharged to the tank through the drain port 32a. At this time, the oil that has reached the passage 48 from the cylinder block center hole 42c branches off, while
5 and the sheet 46 are lubricated at the spherical contact, and the other Q
In a, the fluid accumulates in the groove 46a through the communication hole 46b. Therefore, the entire circumference between the center shaft 35 and the seat 46 is lubricated and cooled by the oil from the cylinder block center hole 42c and the oil accumulated in the groove 46a. For this reason, the oil film thickness changes due to the pressure generated in the gap between the cylinder block 42 and the valve plate 43, and the change in the oil film thickness causes the cylinder block 42 to vibrate in the left-right direction in the drawing, and the cylinder block central hole 42c and the seat The problem that the outer diameter of 46 is seized is eliminated.

As described above, even if the misalignment between the components of the piston pump and the motor accumulates, the center shaft 5
Since the contact portion between the seat 2 and the seat 46 is formed into a swingable spherical shape, the spherical contact portion Sa can slide while swinging, and the spherical sliding surface between the cylinder block 42 and the valve plate 43 is aligned. Therefore, the seat 46 may be inserted into the cylinder block center hole 42c in a pivotally tight manner, and the dimension thereof may be a maximum diameter gap of about 0.026 mm and may be inserted pivotally. Therefore, the diameter gap is at most about 1 in comparison with the past.
/ 3, and the cylinder block 42 does not rotate while being swung largely in the diameter direction.
It is possible to prevent galling and seizure of the spherical sliding surface and leakage from a high pressure region to a low pressure region in response to the increase in pressure. If the gap between the center shaft 52 and the hole 51a of the cylinder block 51 is set to 0.026 mm as in the conventional example,
The concave spherical surface of the cylinder block 51 and the valve plate 54
A gap of about 0.057 mm is opened at the mating surface with the convex spherical surface 54a of the cylinder, and the high pressure oil leaks from this mating surface to deteriorate the performance, and the concave spherical surface of the cylinder block 51 and the convex spherical surface of the valve plate 54 There is a problem that the contact with 54a is caused to be one side and burning occurs.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston motor of the present invention.

FIG. 2 is a partially enlarged sectional view of the piston motor of the present invention.

FIG. 3 is a sectional view of a conventional piston motor.

FIG. 4 is a sectional view of another conventional piston motor.

[Explanation of symbols]

 31 Drive shaft 32 Case 33, 34 Bearing 35 Center shaft 35a Ball 36 Piston assembly 37 Rod 38 Piston 42 Cylinder block 42c Cylinder block central hole 43 Valve plate 46 Seat 60 Tilt angle control device

Claims (1)

[Claims] An oblique-axis axial piston pump / motor in which a drive shaft and a cylinder block are connected via a piston assembly including a piston and a rod and the cylinder block and a valve plate have a spherical shape. A spring that generates a force that presses the valve against the valve plate, a seat that can slide in the hole longitudinal direction with respect to the hole in the center of the cylinder block, a center shaft, and a spherical shape that can swing the contact portion of the seat. And a means for lubricating between the seat outer diameter and the center hole of the cylinder block, and a means for lubricating between the seat outer diameter and the center hole of the cylinder block is provided.