JPH0463233B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to an axial piston machine, and more specifically, to an axial piston machine in which a cylinder block is rotatably supported in a mechanical body, and a plurality of piston chambers are formed in the cylinder block. In addition, a piston is arranged in each piston chamber so as to be freely retractable, and the head of each piston is brought into contact with a swash plate, so that each piston is reciprocated in the axial direction as the cylinder block rotates. It concerns axial piston 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,
This is because if the swash plate and neutral position are not accurate, the device will be driven at the same time as the engine is started, which is extremely 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 disclosed in Japanese Utility Model Application No. 116083/1983. This device, as shown in FIG. A structure in which the fitting member 53 is brought into pressure contact with a free end surface 56 of a positioning member 55 that rotates in conjunction with a spring 57, and a recess 58 into which the fitting member 53 fits is formed in the free end surface 56. belongs to. With this structure, when the positioning member 55 rotates together with the swash plate 54 and reaches the neutral position, the fitting member 53 moves into the recess 5.
8, 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 of assembling the device, a problem may occur where the swash plate 54 is not in the neutral position even though the recess 58 and the fitting member 53 are in a fitted state due to processing accuracy and assembly accuracy. This is because 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 be able to absorb the error even if there is an error in the neutral position of the swash plate 54 as described above. Moreover, it is an object of the present invention to provide an axial piston machine in which the motor can be idled when the machine is stopped, and maintenance work can be facilitated.

(Means for Solving the Problems) Therefore, in the axial piston machine of the invention, a pump rotor 5 is rotatably supported in the machine body 3, and a plurality of piston chambers 6 are formed in the pump rotor 5. A hydraulic pump 1 has pistons 7 arranged so as to be freely protrusive and retractable, and the head of each piston 7 is in contact with a movable swash plate 8, and a motor rotating body 14 is rotatably supported in a machine body 3, The hydraulic motor 2 has a hydraulic motor 2 in which pistons 12 are disposed in a plurality of piston chambers 13 formed in the motor rotating body 14 so as to be retractable and retractable, and the head of each piston 12 is brought into contact with the swash plate 11. Discharge port 1 of pressure pump 1
9 and the inlet 20 of the hydraulic motor 2 are connected to the high pressure side flow path 2.
1, and in the axial piston machine in which the inlet 22 of the hydraulic motor 2 and the suction port 23 of the hydraulic pump 1 are connected by a low-pressure side passage 24 to form a closed circuit, the high-pressure side passage 21 and the low-pressure side flow path 24 through a bypass flow path 30, and a bypass valve 32 for opening and closing this bypass flow path 30 is provided. It is characterized in that an orifice 34 is formed to communicate the flow path 24 on the low pressure side.

(Function) In the above-mentioned 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. That is, 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 working fluid is discharged from the piston chamber 6 into the high pressure side flow path 21. However, 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 passes through the orifice 34 and flows into the low-pressure side flow path 24.
This means that a neutral state can be maintained.

Also, when the machine is stopped, by opening the bypass valve 32 and communicating the bypass flow path 30,
It becomes possible to idle the hydraulic motor 2 and its driven objects, such as wheels.

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

Figures 1 and 2 show a variable displacement hydraulic pump 1.
1 and a constant displacement hydraulic motor 2 are housed in a common casing 3, which is a so-called integrated fluid transmission device. The hydraulic pump 1 has an input shaft 4 connected to a drive source (not shown) such as an engine, and is attached to the input shaft 4.
A pump rotating body 5 that is rotationally driven, pistons 7 that are disposed in a plurality of piston chambers 6 formed in the pump rotating body 5 so as to be freely retractable, and a movable swash plate 8 that the head of each piston 7 contacts. 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 has a fixed swash plate 11 fixed in the casing 3, and is driven to rotate along the fixed swash plate 11 while moving in and out. The motor includes a plurality of pistons 12, a motor rotating body 14 having a piston chamber 13 in which each piston 12 is retractably arranged, and an output shaft 15 connected to the motor rotating body 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. An inlet 23 is formed, and an inlet 20 and an outlet 22 are formed corresponding to the hydraulic motor 2, and a first channel 21 and an outlet 22 are formed to connect the outlet 19 and the inlet 20.
A second flow path 24 is formed that connects the suction port 23 and the suction port 23 . In other words, inside the side wall 18, there is a first flow path 21 that becomes a high pressure side flow path and a second flow path 24 that becomes a low pressure side flow path.
A closed circuit is formed by this.

A bypass flow path 3 that communicates the first flow path 21 and the second flow path 24 is provided in the lower part of the side wall 18.
0 is formed, and a bypass valve 32 is in contact with a valve notch 31 formed at one end of this bypass flow path 30. This bypass valve 32
is held by a valve operating part 33 attached to the side wall 18 so as to be able to approach and move away from the valve seat 31, and a vertical hole 35 along the radial direction is formed inside the valve seat 31.
and an orifice 34 communicating with the vertical hole 35 and extending 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 operation section 33 is used during maintenance and the like, and is normally kept in a state in which the bypass valve 32 remains in contact with the valve seat 31. In other words, when the machine is stopped, by opening the bypass valve 32 and communicating the bypass passage 30, it is possible to idle the hydraulic motor 2 and its driven objects, such as wheels. As a result, maintenance work can be performed easily.

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 activation source,
Each piston 7 in contact with the movable swash plate 8 reciprocates in the axial direction. As a result, the working fluid is discharged from the discharge port 19 into the first channel 21, and this working fluid descends in the first channel 21 and enters the inlet 20 of the hydraulic motor 2, causing the motor to rotate. body 1
Rotate 4. In other words, the output shaft 15 is rotated. After that, from the outlet 22 to the second flow path 24
The liquid flows out into the interior, rises within this second flow path 24, and is sucked into the suction port 23 of the hydraulic pump 1.

Next, when the hydraulic motor 2 is to be stopped, the movable swash plate 8 is positioned at the neutral position using the operating lever, but at this time there is no error in the neutral position of the movable swash plate 8. In this case, input shaft 4
Even if the pump rotating body 5 rotates together with the rotation of the pump rotor 5, each piston 7 does not reciprocate, and thereby the hydraulic motor 2 stops. However, in the above case, if there is an error in the neutral position of the movable swash plate 5, that is, if the operating lever is in the neutral position but the swash plate 8 is not in the correct neutral position, the rotation of the pump rotating body 5 At the same time, each piston 7 reciprocates in the axial direction, and the working fluid is discharged from the discharge port 19 into the first flow path 21 . However, in the device of this embodiment, the bypass valve 32 is
Since the internal orifice 34 is formed,
The working fluid discharged into the first flow path 21 passes through the orifice 34 and is bypassed to the bypass flow path 30, so that the pressure within the first flow path 21 does not increase and the pressure in the hydraulic motor 2 increases. Driving is thus prevented. In other words, the error in the neutral position is absorbed.

In the above embodiment, when the high pressure side flow path 21 and the low pressure side flow path 24 are communicated via the orifice 34, the orifice 34 is formed in the bypass 32, so that existing equipment can be used. It can be implemented extremely easily and inexpensively. It is also possible to reduce the circuit gain, thereby making it possible to alleviate the jerky motion that conventionally occurs due to too high a gain.

Further, according to the above embodiment, it is possible to absorb the error in the neutral position of the movable swash plate 8, so when operating the swash plate 8 using the operating lever,
This creates play in the control lever, which prevents sudden startup and improves safety. Moreover, since the use of the orifice 34 also provides a relief effect, it is 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 an orifice, so that the working fluid in the high-pressure side flow path can be controlled. It can be bypassed to the low pressure side flow path through the orifice, thereby maintaining a neutral state. In addition, when the machine is stopped, by opening the bypass valve and communicating the bypass flow path, it is possible to idle the hydraulic motor and its driven objects, such as wheels, and as a result, maintenance work is facilitated. You will be able to do this.

[Brief explanation of drawings]

1 and 2 show an embodiment of the axial piston machine of the present invention, in which FIG. 1 is a longitudinal section of a fluid transmission device (-cross section in FIG. 2);
Figure 2 is a longitudinal cross-sectional view of the same device seen from different angles.
FIG. 3 is an explanatory diagram of a conventional example. 1... Hydraulic pump, 2... Hydraulic motor, 3...
Casing (machine body), 5...Pump rotating body,
6, 13... Piston chamber, 7, 12... Piston, 8... Movable swash plate, 11... Swash plate, 14... Motor rotating body, 19... Air outlet, 20... Inflow port,
21... First channel (high pressure side channel), 22... Outlet, 23... Suction port, 24... Second channel (low pressure side channel), 30... Bypass channel, 32... Bypass valve, 34...orifice.

Claims (1)

[Claims] 1. A pump rotating body 5 is rotatably supported in the machine body 3, and pistons 7 are disposed in a plurality of piston chambers 6 formed in the pump rotating body 5 so as to be freely retractable, and the head of each piston 7 is movable. A hydraulic pump 1 is in contact with a swash plate 8, and a motor rotating body 14 is rotatably supported in the machine body 3, and a piston 12 is inserted into and retracted from a plurality of piston chambers 13 formed in the motor rotating body 14. It has a hydraulic motor 2 which is freely arranged and has the head of each piston 12 in contact with the swash plate 11, and the discharge port 19 of the hydraulic pump 1 and the inlet port 20 of the hydraulic motor 2 are connected to high pressure. Side channel 21
In addition, in the axial piston machine in which the outlet 22 of the hydraulic motor 2 and the suction port 23 of the hydraulic pump 1 are connected by a low-pressure side flow path 24 to form a closed circuit, the high-pressure side flow path 21 A bypass flow path 30 connects the and low pressure side flow path 24, and a bypass valve 32 is provided to open and close this bypass flow path 30. Furthermore, the bypass valve 32 is connected to the high pressure side flow path 21 and the high pressure side flow path 24 when the bypass valve 32 is closed. An axial piston machine characterized in that an orifice 34 is formed to communicate with a low pressure side flow path 24.