JPH06117358A - Rocker cam tilt rotation device for variable pump and motor - Google Patents

Abstract

PURPOSE:To enlarge tilt rotation force of a rocker cam, equalize a tilt rotation of the rocker cam whichever port is under high pressure, automatically change over the rocker cam, and hold a specified angle of the rocker cam as required. CONSTITUTION:Control ports 42 are formed on a top dead center side and a bottom dead center side of a portion between a first port 40 and a second port 41 of a valve plate 15. A changeover valve 47 for switching supply of high-pressure oil is installed on one of the control ports 42. The changeover valve is changed over by spring force and the pressure of the high-pressure oil, so as to automatically change over an angle of a rocker cam. An auxiliary changeover valve 52 is provided for fixing the changeover valve to a one side position, so that a specified angle of the rocker cam can be kept irrespective of the pressure of the high-pressure oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention tilts a rocker cam of a variable pump motor, particularly a variable motor used as a traveling motor, by rocking the rocker cam to change the rotational speed, the discharge amount, that is, the displacement. Related to the device.

[0002]

2. Description of the Related Art In a variable pump / motor, a piston is inserted into a cylinder hole of a cylinder block rotatably supported with a shaft in a housing to form a cylinder chamber, and the piston is mounted along a rocker cam supported on the housing. It is connected to a sliding piston shoe, and the cylinder chamber is alternately communicated with the hydraulic pressure source and the tank via a first and a second port of a substantially semicircular shape formed in a valve plate every time it rotates by about 180 degrees. When the cylinder block rotates, the piston expands and contracts to discharge, and suction is repeated.By tilting the rocker cam and changing its angle, the piston stroke changes and the rotation speed and discharge amount can be changed. To do. As a device for tilting the rocker cam described above, for example, a device disclosed in Japanese Utility Model Laid-Open No. 62-169268 is known. That is, as shown in FIG. 1, a control port d is formed on the valve plate a at the top dead center side between the first port b and the second port c, and the control port d is formed by the two-position switching valve e. When the high pressure side ports of the second ports b and c are connected to the tank f and high pressure oil is supplied to the control port d, the moment force application point A _{1 of the} piston is closer to the top dead center than the rocker cam tilt center g. When the rocker cam is tilted and the control port d is communicated with the tank f, the moment force application point A _{1 of the} piston is slightly closer to the bottom dead center than the rocker cam tilt center g, and the rocker cam returns to its original tilt position. Like In the example shown in FIG. 2, the control port d is formed on each of the top dead center side and the bottom dead center side, and high pressure oil is supplied to the control port d by the two-position switching valve e. If high-pressure oil is supplied to d, the moment force application point A _{1 of the} piston will be closer to the top dead center than the rocker cam tilt center g, and if high-pressure oil is supplied to the control port d on the bottom dead center side, the moment force application point A of the piston will be A. ₁ is closer to the bottom dead center than the rocker cam tilt center g, whereby the rocker cam is tilted to the top dead center side and the bottom dead center side.

[0003]

[Problems to be Solved by the Invention] In the former case,
When the control port d is communicated with the tank f, the tilting force acting on the rocker cam is weak, the tilting speed of the rocker cam is slow, and the responsiveness deteriorates. In the latter case, the tilting force acting on the rocker cam increases in both cases, but when used as a motor etc. not limited to traveling, the high pressure side port reverses between forward rotation and reverse rotation. Therefore, the high pressure position guided to the control port in the forward rotation and the reverse rotation reverses, and the rocker cam becomes unstable, so it cannot be used as a motor. In addition, if both of them are used, the switching valve e can be switched by electricity and pilot pressure oil, so that the operator needs to switch the switching valve e by operating the switch and pilot valve, which not only makes the operation troublesome. , There may be a mistake in operation contrary to the required capacity. For example, when it is used as a motor for traveling, it is necessary to have a high-speed rotation state during high-speed traveling and a low-speed rotation state during low-speed traveling. There is.

Therefore, an object of the present invention is to provide a rocker cam tilting device for a variable pump / motor, which can solve the above-mentioned problems.

[0005]

[Means and Actions for Solving the Problem] Control ports are formed at the intermediate top dead center side and the bottom dead center side of the first and second ports of the valve plate, respectively, and the control ports of the high pressure side of the first and second ports are formed. A switching valve that supplies high-pressure oil to one control port and connects the other control port to the case drain is provided.The switching valve is operated to switch between spring force and high-pressure oil pressure. An auxiliary switching valve that fixes the switching operation.

[0006]

[Operation] When tilting the rocker cam, a large tilting force acts, and even if the high pressure port is reversed, high pressure oil can be supplied to the same control port, and the other control port Even if the high pressure port is reversed, it will be connected to the case drain side, the switching valve will be automatically switched according to the pressure of the high pressure oil, and switching of the switching valve can be stopped by operating the auxiliary switching valve. .

[0007]

[Examples] As shown in FIG. 3, a cylinder block 4 is rotatably disposed in a housing 3 composed of a case 1 and an end plate 2, and a spline fitting is performed in a spline hole 5 at the center of rotation of the cylinder block 4. One end of the connected shaft 6 is supported by a bearing 8 in a hole 7 of the bottom portion 1a of the case 1, and the other end of the shaft 6 is supported by a bearing 10 in a blind hole 9 of the end plate 2 to form a cylinder block together with the shaft 6. 4 is configured to rotate. The cylinder 4 has a cylinder hole 11
A piston 12 is fitted into the cylinder chamber 13 to form a cylinder chamber 13. The cylinder chamber 13 passes through a port 14 and a valve plate 15
The first shoe and the second port (not shown), which are formed in a substantially semicircular shape, are alternately opened each time it rotates about 180 degrees, and the piston shoe 16 swingably connected to each piston 12 is a shoe retainer 17. It is pressed against the front surface of the rocker cam 18. The rocker cam 18 has a hole 30 through which the shaft 6 passes.
The rear surface 31 has first and second stopper surfaces 32 and 33 having different angles and an arcuate surface 34, and the arcuate surface 34 is an arcuate guide groove 35 formed in the bottom wall 1a of the case 1. The rocker cam 18 is tilted to the top dead center side so that the first stopper surface 32 is attached to the bottom wall 1a of the case 1.
Rocker cam 1 when it hits the front of
The angle of the front surface 37 of the rocker cam 18 decreases when the angle of the front surface 37 of the rocker cam 8 increases and the rocker cam 18 tilts toward the bottom dead center side and the second stopper surface 33 contacts the stopper 36. As shown in FIG. 4, control ports 42 are formed on the top dead center side and the bottom dead center side of the valve plate 15 in the middle of the first port 40 and the second port 41, respectively. 41, the discharge pressure oil of the hydraulic pump 43 is supplied and controlled via the operation valve 44 and the brake valve 45, and the high pressure oil of the first and second ports 40 and 41 thereof is detected by the shuttle valve 46 and the switching valve 47 determines which. It is supplied to one of the control ports 42. The switching valve 47 is provided in the end plate 2 and is held at a first position A by a spring 48.
When pilot pressure oil is supplied to the second pressure receiving portions 49, 50, the pilot type valve is switched to the second position B, and the high pressure oil detected by the shuttle valve 46 is supplied to the first pressure receiving portion 49, and the high pressure When the oil pressure exceeds the set pressure, the spring 48
Against this, the second pressure receiving portion 50 is supplied with pressure oil from an external hydraulic pressure source 51 by means of an auxiliary switching valve 52, and this auxiliary switching valve 52 uses a spring 53 for drain position. When the solenoid 54 is turned on and the solenoid 54 is energized, the pressure oil supply position D is reached.

Next, the operation when used as a traveling motor will be described. Since the load acting on the variable pump / motor is small and the pressure on the high-pressure side port is low during high-speed running,
Since the pressure of the high-pressure oil detected by the shuttle valve 46 is lower than the set pressure, the switching valve 47 is in the first position A by the spring 48. When the switching valve 47 is in the first position A, high pressure oil is supplied to the control port 42 on the bottom dead center side, the control port 42 on the top dead center side is connected to the case drain side, and the moment force application point A _{1 of the} piston is rocker. The rocker cam 18 is located closer to the bottom dead center than the cam tilt center 15a, and a tilting force acts on the rocker cam 18 so that the second stopper surface 33 contacts the stopper 36 and the front surface 37.
Becomes smaller, the tilting angle of the rocker cam 18 becomes smaller, and the stroke of the piston 12 becomes shorter. Therefore, the flow rate required for the cylinder block 4 to make one rotation decreases and the shaft 6 rotates at a high speed. It becomes a high-speed rotation state. Since the load acting on the variable pump / motor is large and the pressure on the high-pressure side port is high during low-speed traveling, the pressure of the high-pressure oil detected by the shuttle valve 46 becomes equal to or higher than the set pressure, and the switching valve 47 causes the pilot pressure oil of the pressure receiving section 49 to operate. Then, the second position B is set against the spring 48. When the switching valve 47 is in the second position B, high pressure oil is supplied to the control port 42 on the top dead center side, the control port 42 on the bottom dead center side is connected to the case drain side, and the moment force application point A _{1 of the} piston is rocker. The cam tilt center is closer to the top dead center 15a, and the tilting force closer to the top dead center acts on the rocker cam 18, the first stopper surface 32 contacts the stopper 36, and the angle of the front surface 37 increases, so that the rocker cam 18 becomes larger. Since the tilt angle of 18 becomes large and the stroke of the piston 12 becomes long, the flow rate required for one rotation of the cylinder block 4 increases and the shaft 6 rotates at low speed. When it is desired to travel at a very low speed depending on the traveling conditions, the solenoid 54 of the auxiliary switching valve 52 is energized to the pressure oil supply position D, so that the second switching valve 47 is operated.
Since the pilot pressure oil can be supplied to the pressure receiving portion 50 and switched to the second position B, even if the pressure of the high pressure oil detected by the shuttle valve 46 is lower than the set pressure, the vehicle can be driven at a low speed and run at a slight speed.

[0009]

The control port 42 is formed on the top dead center side and the bottom dead center side, and the rocker cam 18 is tilted by supplying high pressure oil to one of the control ports 42. Rocker cam 1 even when tilting
Since the tilting force acting on 8 increases and the tilting speed increases, the responsiveness improves. Since the high pressure oil on the high pressure side of the first and second ports 40 and 41 is supplied to the control port 42, the same control port 42 is always used even if the high pressure port is reversed.
The high-pressure oil is supplied to the rocker cam 18, and the rocker cam 18 is stabilized without tilting. The switching valve 47 based on the detected pressure of the high pressure oil and the spring force.
The capacity, for example, the rotation speed can be automatically switched between a high-speed rotation state and a low-speed rotation state by switching the switch, so that the operator does not need to operate the operation, and the operation is simple and there is no erroneous operation. Regardless of the pressure of the high pressure oil detected by switching the auxiliary switching valve 52, the switching valve can be switched so that the capacity, for example, the rotation speed can be set to a low speed rotation state, and the vehicle can run at a very low speed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional example.

FIG. 2 is an explanatory diagram of another conventional example.

FIG. 3 is a sectional view of a variable pump / motor according to the present invention.

FIG. 4 is an explanatory diagram of a rocker cam tilting device.

[Explanation of symbols]

1 case, 4 cylinder block, 6 axes, 11
Cylinder hole, 12 piston, 13 cylinder chamber, 1
5 valve plate, 16 piston shoe, 17 shoe retainer, 18 rocker cam, 40 first port, 41 second port, 42 control port, 47 switching valve, 48 spring, 52 auxiliary switching valve.

Claims (1)

[Claims] 1. A cylinder block (4) is rotatably supported in a case (1) together with a shaft (6), and a piston (12) is inserted into a cylinder hole (11) of the cylinder block (4) to form a cylinder chamber (13). Valve plate 1
5, the piston shoe 16 connected to the first port 40 and the second port 41 in sequence and connected to the piston 12 is slidable along the front surface of the rocker cam 18 in the shoe retainer 1.
In the variable pump / motor pressed by 7, the first port 40 and the second port 41 in the valve plate 15
Control port 42 on the top dead center side and the bottom dead center side in the middle of
To form the first port 40 and the second port 4 respectively.
A switching valve 47 that selectively supplies the high-pressure oil on the high pressure side to the one control port 42 and connects the other control port 42 to the case drain is provided, and the switching valve 47 is provided with a spring force of a spring 48 and a high pressure. A rocker cam tilting device for a variable pump / motor, characterized in that an auxiliary switching valve 52 that outputs a signal for stopping switching of the switching valve 47 is provided for switching operation by oil pressure.