JPS62253967A - Axial piston machinery - Google Patents

Abstract

PURPOSE:To absorb the error even if the error exists in the neutral position for a swash plate by allowing the communication between the high pressure side flow passage communicating to each piston chamber and a low pressure side flow passage through an orifice. CONSTITUTION:On a casing 3, the first low passage 21 connecting a discharge port 19 with an inflow port 20 and the second flow passage 24 connecting an effluence port 22 and a suction port 23 are formed, and a bypass flow passage 30 for the communication between the first flow passage 21 and the second flow passage 24 is formed in the lower part inside a side wall 18, and a bypass valve 32 is attached onto a valve seat 31 formed at one edge part of the bypass flow passage 30, and a longitudinal hole 35 and an orifice 34 which communicates to the longitudinal hole 35 and extends in the axial direction are formed inside the bypass valve 32. Therefore, when a swash plate 8 does not exist at a correct neutral position, working fluid is discharged from a piston chamber 6 to the first flow passage 21, and the working fluid maintains the neutral state, because of the bypass to the second flow passage 24 through the orifice 34.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to an axial piston machine, specifically, a cylinder block is rotatably supported in the machine body, a plurality of piston chambers are formed in the cylinder block, and , an axial piston having a structure in which a piston is disposed in each piston chamber so as to be freely retractable, the head of each piston is brought into contact with a swash plate, and each piston is reciprocated in the axial direction as the cylinder block rotates. It's about machines.

(Prior Art) In variable displacement axial piston pumps and motors that do not have a servo system, it is necessary to accurately set the neutral position of the swash plate. That is, if the neutral position of the swash plate is not accurate, the device will be driven at the same time as the engine is started, which is very dangerous.

Therefore, as a device for accurately setting the neutral position of the swash plate in the above-mentioned axial piston pump or motor, there is, for example, a neutral position control device described in Japanese Utility Model Application No. 116083/1983. As shown in FIG. 7, this device has a recess 52 formed in the inner circumference of a casing 51 of the machine body, a ball-shaped fitting member 53 disposed within the recess 52, and a swash plate 54. Free end surface 5 of positioning member 55 that rotates in conjunction with
6, the fitting member 53 is pressed into contact with the spring 57, and a recess 58 into which the fitting member 53 fits is formed in the free end surface 56.

With such a structure, the positioning member 5
5 rotates together with the swash plate 54 and reaches the neutral position, the fitting member 53 fits into the recess 58, thereby positioning the swash plate 54 at the neutral position.

(Problems to be Solved by the Invention) However, even with the neutral position control device as described above, it is often difficult to accurately position the swash plate 54 at the neutral position. That is, at the stage when the device is assembled, the recess 58 and the fitting member 5 are separated due to processing accuracy and assembly accuracy.
A problem may occur in which the swash plate 54 is not in the neutral position even though the swash plate 54 is in the fitted state.
Further, errors may occur later due to wear of the sliding contact portion due to use.

This invention was made in order to solve the above-mentioned conventional problems, and its purpose is to
An object of the present invention is to provide an axial piston machine capable of absorbing an error even if there is an error in the neutral position of the axial piston.

(Means for solving the problem) Therefore, in the axial piston machine of this invention,
A cylinder block 5 is rotatably supported in the machine body 3, and a plurality of piston chambers 6 are formed in the cylinder block 5. A piston 7 is disposed in each piston chamber 6 so as to be freely retractable. In an axial piston machine whose head is in contact with the swash plate 8, the high-pressure side passage 21 and the low-pressure side passage 24, which communicate with each piston chamber 6, are communicated via an orifice 34.

(Function) In the above-described axial piston machine, even if there is an error in the neutral position of the swash plate 8, the error can be absorbed as follows. In other words, if the swash plate 8 is not in the correct neutral position, each piston 7 reciprocates in the axial direction with the rotation of the cylinder block 5, and the piston chamber 6
The working fluid is discharged into the high pressure side flow path 21 from the high pressure side flow path 21, but since the high pressure side flow path 21 and the low pressure side flow path 24 are communicated via the orifice 34, the working fluid is discharged into the orifice 34. Through this, a bypass is made to the low-pressure side flow path 24, thereby making it possible to maintain a neutral state.

(Embodiments) Next, specific embodiments of the axial piston machine of the present invention will be described in detail with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of a so-called integrated fluid transmission in which both a variable displacement wave pressure pump 1 and a constant displacement hydraulic motor 2 are housed in a common casing 3. The device is shown. The hydraulic pump 1 is
Human power shaft 4 connected to a drive source (not shown) such as an engine
, a pump rotating body (cylinder block) 5 attached to this human power shaft 4 and rotationally driven, and pistons 7 disposed in a plurality of piston chambers 6 formed in this pump rotating body 5 so as to be freely retractable. and a movable swash plate 8 with which the head of each piston 7 comes into contact, and the movable swash plate 8 is connected to an operating lever (not shown) outside the casing 3.

The hydraulic motor 2 has almost the same structure as the hydraulic pump 1, and is driven to rotate along the fixed swash plate 11 while moving in and out. A plurality of pistons 12 and each piston 12
The motor includes a rotating motor (cylinder block) 14 having a piston chamber 13 in which a piston chamber 13 is arranged so as to be freely retractable, and an output shaft 15 connected to the rotating motor 14.

The casing 3 houses both the hydraulic pump 1 and the hydraulic motor 2, and one of the side walls 18 has a discharge port 19 and a suction port corresponding to the hydraulic pump 1. A port 23 is formed, and an inlet 20 and an outlet 22 are formed corresponding to the hydraulic motor 2, and a first flow path 21 connecting the discharge port 19 and the inlet 20 and the outlet 22 are also formed. A second flow path 24 is formed that connects the suction port 23.

In other words, inside the side wall 18 there is a first flow path 2 serving as a high pressure side flow path.
1 and the second flow path 24, which is a low-pressure side flow path, form a closed circuit.

A bypass flow path 30 that communicates the first flow path 21 and the second flow path 24 is formed inside the side wall 18, and a valve seat 31 is formed at one end of the bypass flow path 30. A bypass valve 32 is in contact with the. This bypass valve 32 is held by a valve operation part 33 attached to the side wall 18 so as to be able to approach and move away from the valve seat 31, and has a vertical hole 35 along the radial direction inside the bypass valve 32, and a vertical hole 35 along the radial direction. An orifice 34 is formed that communicates with and extends in the axial direction. Therefore, the first flow path 21 and the bypass flow path 30 are in communication with each other through the vertical hole 35 and the orifice 34 . Note that the valve operating section 33 is used during maintenance and the like, and normally leaves the bypass valve 32 in contact with the valve seat 31.

Next, the operating state of the fluid transmission device will be explained. First, during normal operation, the movable swash plate 8 is positioned at a predetermined inclined position by the operating lever. Then, the pump rotating body 5 rotates together with the input shaft 4 rotated by the drive source, and each piston 7 contacts the movable swash plate 8.
will reciprocate in the axial direction. As a result, the discharge port 1
Working fluid is discharged from 9 into the first flow path 21, and this working fluid descends inside the first flow path 21, enters the inlet 2.0 of the hydraulic motor 2, and enters the motor rotating body 14. Rotate. In other words, the output shaft 15 is rotated.

Thereafter, the liquid flows out from the outlet 22 into the second flow path 24, rises within the second flow path 24, and is sucked into the suction port 23 of the hydraulic pump 1.

Next, when the hydraulic motor 2 is stopped, the movable swash plate 8 is positioned at the neutral position by the operation lever. At this time, if there is no error in the neutral position of the movable swash plate 8, , as the input shaft 4 rotates, the pump rotating body 5
Even if the swash plate 8 rotates, each piston 7 does not reciprocate, which causes the hydraulic motor 2 to stop. However, in the above case, if there is an error in the neutral position of the movable swash plate 8, that is, the operating lever is in the neutral position. position, but the swash plate 8 is not in the correct neutral position, each piston 7 reciprocates in the axial direction with the rotation of the pump rotating body 5, and the swash plate 8 moves from the discharge port 19 into the first flow path 21. Working fluid will be discharged.

However, in the device of this embodiment, since the orifice 34 is formed inside the bypass valve 32 as described above, the working fluid discharged into the first flow path 21 passes through the orifice 34 and into the bypass flow path 30. Therefore, the pressure in the first flow path 21 does not increase, and the hydraulic motor 2 is prevented from being driven. In other words, the error in the neutral position is absorbed.

In the first embodiment, the orifice 34 is formed in the bypass valve 32 when communicating the high-pressure side flow path 21 and the low-pressure side flow path 24 via the orifice 34, so that the existing device can be used. It can be carried out very easily and inexpensively. It is also possible to reduce the circuit gain, thereby alleviating the jerky motion that conventionally occurs due to too high a gain.

FIG. 3 shows a second embodiment. That is, in the fluid transmission device as described above, instead of forming the orifice 34 in the bypass valve 32, the opening edges of the discharge port 19, the suction port 23, the inlet port 20, and the outlet port 22 are formed at both ends of each opening, as shown in the figure. A notch 37 for communicating the high pressure side flow path 21 and the low pressure side flow path 24 is formed in the portion. This also makes it possible to absorb errors in the neutral position of the movable swash plate 8. That is, 19 days each day.
23. If notches 37 are formed at both ends of the opening edge of 23, in a direction that approaches each other, each of these notches 37 will serve as a passage and an orifice, and the first flow path 21
communicates with the openings 6A, 13A of the piston chamber 6.13 via a notch 37 on either the upper side or the lower side,
These openings 6A, 13^ communicate with the second flow path 24 via the adjacent notch 37. Therefore, the high-pressure side flow path 21 and the low-pressure side flow path 24 communicate with each other, and the error in the neutral position of the movable swash plate 8 is absorbed as in the first embodiment. Note that the notch 37 may be formed only at the discharge port 19 and the suction port 23, or only at the inlet port 20 and the outlet port 22.

4 to 6 show a third embodiment.

That is, in the first and second embodiments described above, an example was given in which the orifice 34, 37 was arranged between the high pressure side flow path 21 and the low pressure side flow path 24 in the side wall 18.
In this embodiment, a narrow groove 38 is formed on the side end surface of the side wall 18 of either the pump rotating body 5 or the motor rotating body 14, or both, so that the openings 6A of the adjacent piston chambers 6 communicate with each other. This is how it was done. In other words, this narrow groove 38 serves as both a passage and an orifice.
This also makes it possible to absorb errors in the neutral position of the movable swash plate 8, as in the second embodiment.

In the second and third embodiments described above, the notch 37 or I groove 38 is formed in an existing part when communicating the high pressure side flow path 21 and the low pressure side flow path 24, so the part concerned It is possible to carry out this process without adding additional machining or additional machining. Further, according to the first to third embodiments described above, it is possible to absorb the error in the neutral position of the movable swash plate 8, so when the swash plate 8 is operated by the operating lever, This creates play in the control lever, which prevents sudden startup and improves safety. Furthermore, the use of the orifices 34, 37, and 38 also provides a relief effect, making it possible to prevent the pressure in the high-pressure side channel from becoming abnormally high.

(Effects of the Invention) In the axial piston machine of the present invention, the high-pressure side flow path and the low-pressure side flow path that communicate with each piston chamber are communicated via the orifice, so that the working fluid in the high-pressure side flow path is It is possible to bypass the flow path through the orifice to the low pressure side flow path, thereby maintaining a neutral state.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the axial piston machine of the present invention, FIG. 1 is a longitudinal cross-sectional view of the fluid transmission device (cross-sectional view taken along I-■ in FIG. 2), and FIG. FIG. 3 is a longitudinal sectional view of the fluid transmission device showing the second embodiment, FIGS. 4 to 6 show the third embodiment, and FIG. 4 shows the pump rotating body. (Cylinder block), FIG. 5 is a longitudinal sectional view thereof, FIG. 6 is a sectional view taken along the line IV-rV in FIG. 4, and FIG. 7 is an explanatory diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Hydraulic pump, 2... Hydraulic motor, 3... Casing, 5... Pump rotating body, 6... Piston chamber, 7... Piston, 8... Movable swash plate , 21...first flow path, 24...second flow path, 34...orifice. Patent Applicant: Daikin Industries, Ltd. Figure 2 Figure 3 Figure 4 Figure 5 Words Figure Δ Figure 7 Procedure Neho Correction 'IF (Method) % Formula % 2. Name of Invention Axial Piston Machine 3. Amendment Relationship with the case of the person who did the patent application New Hankyu Building (28
5) Daikin Industries, Ltd. Representative Yama 1) Minoru 4, Agent Showa 6, 3rd floor, Taiyo Building, 2-16 Awajicho, Higashi-ku, Osaka
May 7, 1 year (Shipping date: May 27, 1 year) 6. Subject to amendment.

Claims (1)

[Claims] 1. A cylinder block (5) is rotatably supported in the machine body (3), and a plurality of piston chambers (6) are formed in the cylinder block (5), and each piston chamber (6)
In an axial piston machine, a piston (7) is disposed in each of the piston chambers (7) so as to be retractable, and the head of each piston (7) is in contact with a swash plate (8). An axial piston machine characterized in that a passage (21) and a low pressure side passage (24) are communicated via an orifice (34).