JPH0571796B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable hydraulic motor, and more particularly to a swash plate type hydraulic motor that is used in power shovels, bulldozers, shovel dozers, etc. and is variable between high and low speeds.

Examples of this type of swash plate type hydraulic motor include:
The one disclosed in Japanese Patent Publication No. 52-20403 is known.

This hydraulic motor has a casing and a valve body attached to the casing, and the casing includes an output shaft, a swash plate, and a cylinder block.
A swash plate control cylinder and a switching valve for switching the swash plate control cylinder from a high pressure side to a low pressure side are built into the valve body, and the valve body is arranged on the upper surface of the casing parallel to the output shaft.

According to this hydraulic motor, the piston of the swash plate control cylinder is expanded and contracted, and the tilt angle of the swash plate is controlled in accordance with the expansion and contraction of the piston.

However, the cylinder block is normally connected to a hydraulic power source via a drive circuit and a counterbalance valve, but in the above hydraulic motor, the counterbalance valve is provided outside the casing, so the counterbalance valve and drive circuit are connected to each other. The circuit piping that connects the circuit becomes longer. Moreover, since the valve body is arranged parallel to the casing, the length of the circuit within the valve body connected to the control cylinder becomes long. Therefore, the piping is troublesome and there is a problem that the resistance of the entire pipe becomes large.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a variable hydraulic motor that has compact piping and can reduce piping resistance.

In order to achieve the above object, the configuration of the present invention is as follows:
A drive circuit of the hydraulic motor is selectively connected to the pump or tank via a switching control valve, and a swash plate control cylinder for controlling the tilt angle of the swash plate of the hydraulic motor is connected to the drive circuit or the low pressure circuit via a pilot control valve. In a hydraulic motor, the pilot control circuit that switches and controls the pilot control valve is connected to the pump or tank via the high-speed/low-speed control switching valve. has
A swash plate, a cylinder block, a swash plate control cylinder, and an output shaft projecting outward are provided in the casing.
A pilot control valve is provided in the body, the body is attached to an end surface of the casing opposite to the output shaft, a circuit is provided in the body for connecting the drive circuit and the pilot control valve, and the pilot control valve and the swash plate are connected to each other. It is characterized in that a circuit connecting the control cylinder is formed in the casing and the body.

Examples of the present invention will be described below.

FIG. 1 shows a hydraulic circuit according to a preferred embodiment of the present invention.

That is, the hydraulic motor 51 is connected to the hydraulic drive circuits 58, 5
9, the counterbalance valve 60 is connected to one of the three positions of the switching control valve 55a through supply/discharge circuits 58a and 59a, which are the main oil circuits. Each position of the switching control valve 55a is selectively connected to the pump 56 or the tank 57 at the time of switching.

On the other hand, the swash plate 52 of the hydraulic motor 51 is connected to the rod 53a of the swash plate control cylinder 53, and the piston chamber 5
3b, the rod 53a moves to the right against the spring 53c, thereby moving the swash plate 52 clockwise in the figure to control the hydraulic motor 51 at high speed, and conversely, the piston chamber 53b moves to the right. When connected to the tank side, the restoring force of the spring 53c causes the rod 53a to move to the left, moving the swash plate 52 counterclockwise and controlling the hydraulic motor 51 at a low speed.

The piston chamber 53b of the swash plate control cylinder 53 is selectively connected to either the upper or lower position of the pilot control valve 62 via the circuit 61. When connected to the upper position, high pressure is introduced to the piston chamber 53b, and the lower When connected to the side position, it communicates with the tank 57 side via the low pressure circuits 71, 71a. The low pressure circuit 71a includes a drain circuit a of the hydraulic motor 51 and a swash plate control cylinder 5.
The drain circuit b of No. 3 is connected to return leaked oil to the tank 57.

A pilot control circuit 63 facing the spring on one side is connected to the pilot control valve 62, and this pilot control circuit 63 sets the high speed/low speed control switching valve 55 to either the lower low speed position or the upper high speed position. It is selectively connected to a pump 56 or 57 via the pump 56 or 57.

Further, either the upper or lower position of the pilot control valve 62 is selectively connected to a control circuit 64, and this control circuit 64 is connected to the hydraulic drive circuit 5 via branch circuits 65, 66 and check valves 67, 68.
8,59.

69 and 70 are known brake valves, and 72 is a swivel joint. Inside the swivel joint 72, oil supply/discharge circuits 58a, 59a, a low pressure circuit 71a, and a pilot control circuit 63 pass through and are converged. For this purpose, the traveling motor section 50 is arranged, for example, on the wheel side of the power shovel, and the pump 5
6. Even if the tank 57, switching valve 55, and switching control valve 55a are placed on the vehicle body side near the driver's seat,
When the car body turns during work, each of the circuits mentioned above is held by a swivel joint, preventing them from twisting or tangling, and preventing damage.

The following operation will be described.

When driving the hydraulic motor 51 at high speed, the switching control valve 55a is switched to the upper position, for example, and another switching valve 5 for high-speed/low-speed control is switched.
5 to the upper position. At this time pump 5
6 acts on the pilot control valve 62 via the switching valve 55 and the pilot control circuit 63, and this pilot pressure causes the pilot control valve 6 to
2 to the upper position, thereby connecting the control circuit 64 to the circuit 61. On the other hand, the pressure oil from the pump 56 is guided to the oil supply/discharge circuit 58a from the upper position of the switching control valve 55a, and this circuit 5
The pilot pressure of 8a is the counterbalance valve 6.
0 to the upper position, the circuit 58a
The pressure oil is guided to the drive circuit 58 and the hydraulic motor 51
At the same time, a part of the pressure oil is guided to the piston chamber 53b through a circuit 66, a check valve 68, a control circuit 64, a pilot control valve 62, and a circuit 61 branched from the drive circuit 58. Therefore, the rod 53a of the swash plate control cylinder 53 moves to the right, the swash plate 52 moves clockwise, and the hydraulic motor 51 is driven at high speed. At this time, the hydraulic oil discharged into the drive circuit 59 is transferred to the counter balance valve 60 - circuit 59a -
It is discharged into the tank 57 via the switching control valve 55a.

Next, when controlling the hydraulic motor 51 at low speed,
The high-speed/low-speed control switching valve 55 is switched to the lower position. At this time, since the pilot control circuit 63 communicates with the tank 57, the pilot control valve 62 is switched to the lower position by the spring force, and the circuit 64 is cut off, and at the same time the piston chamber 5
3b is connected to tank 57 via circuit 61, pilot control valve 62, and low pressure circuit 71. Therefore, the pressure in the piston chamber 53b becomes low and the spring 5
The restoring force of 3c causes the rod 53a to move to the left, and the swash plate 5
2 counterclockwise to drive the hydraulic motor 51 at low speed.

During the above-mentioned high-speed drive, for example, when a vehicle such as a power shovel operates the brakes or travels down a steep slope, the hydraulic motor 51 has inertia and performs a pumping action. At this time, since the pressure in the drive circuit 59 is high, this pressure is led to the piston chamber 53b via the branch circuit 65, the check valve 67, the circuit 64, the pilot control valve 62, and the circuit 61.
b can be maintained at a high pressure, making it possible to maintain a high speed range.

Next, an example of a hydraulic motor and its drive device will be described.

As shown in FIG. 2, the hydraulic motor has an output shaft 2 built into a casing 1, a cylinder block 3, a swash plate 4, and a plate 5. A counterbalance valve 60 is installed on the side of the casing 1. A body 60a incorporating the pilot control valve 62 and a body 62a incorporating the pilot control valve 62 are connected to each other via a flange 80 and a bolt 80a. In this case, the bodies 60a, 62a are arranged on the opposite side of the output shaft 2, and the outer dimensions of the mounting surfaces of the bodies 60a, 62a are smaller than the outer dimensions of the mounting surface of the casing 1. Flange 8 on casing 1
1 is formed, and this flange 81 has a body 60.
The bolts for attaching the casing are inserted without being interfered with by a and 62a. A rotating body that interlocks with the output shaft 2 is provided on the outer periphery of the casing 1 .

The casing 1 has a hollow portion 10 therein, and the output shaft 2 is pivotally mounted at the center.
The hollow portion 10 has the cylinder block 3, swash plate 4, and plate 5.
Further, the casing 1 is provided with an oil passage 13 corresponding to the suction oil passage 11, the discharge oil passage 12, and the circuit 61, and furthermore, an auxiliary cylinder 14 serving as a piston chamber 53b communicating with the oil passage 13 is provided. It is provided. Inside this auxiliary cylinder 14 is an oil passage 1.
A pressing member is fitted in the form of a swash plate control piston 53 which is slid by hydraulic pressure acting through the auxiliary plunger 15 and the auxiliary shaft 1.
6, and an auxiliary shoe 16 is rotatably fitted to the tip of the auxiliary plunger 15.

The output shaft 2 is pivotally connected via a bearing 20 provided at the center of the body 60 a and a bearing 21 provided at the center of the casing 1 , and is sealed by a seal member 22 . The cylinder blocks 3 are connected at their centers by a spline connection, and the cylinder blocks 3 are held in the hollow part 10 so that they can rotate.

Further, it goes without saying that the method of connecting the cylinder block 3 to the output shaft 2 may be arbitrarily selected in addition to the spline connection described above.

The cylinder block 3 is formed into a thick disk shape as a whole, and a plurality of cylinders 30 are bored therein. A plunger 31 is inserted into the cylinder 30 from an opening at one end, and a shoe 32 is rotatably fitted to the tip of the plunger 31. The front end surface of this shoe 32 is in contact with the swash plate 4. This swash plate 4 corresponds to the swash plate 52 in FIG. A port 33 is formed at a portion corresponding to the center of the other end of the cylinder 30, passing through the thickness of the cylinder block 3. This port 33 is configured to selectively communicate with the suction oil passage 11 or the discharge oil passage 12 depending on the rotation of the cylinder block 3. Further, this cylinder block 3 is provided with a pressing device that always presses the cylinder block 3 against the plate 5 and the shoe 32 against the swash plate 4 at all times. That is, a space of an appropriate size is formed in a portion adjacent to the output shaft 2 near the center of the cylinder block 3, and a stopper 34 is drilled into the space from the cylinder block 3, and one piece is attached to the stopper 34. 35a, one end of the spring 36 is held by the piece 35a, and the other end of the spring 36 is held by the other piece 35b, and the rod 37 passing through the cylinder block 3 is held by the other piece 35b. A cam 38 is brought into contact with the tip of this rod 37, and a stopper piece 39 attached to the shoe 32 is brought into contact with the cam surface of this cam 38. That is, in this pressing device, the cylinder block 3 is pressed against the plate 5 by the repulsive force of the spring 36, and the shoe 32 is pressed against the swash plate 4 by the stopper piece 39. Therefore, when the inside of the cylinder 30 changes from an unpressurized state to a pressurized state, there is a risk that oil will leak from between the cylinder rod 3 and the plate 5 and the rotation of the cylinder block 3 will be inhibited. This makes it possible to smoothly rotate the cylinder block 3 and rotate the output shaft 2.

The swash plate 4 is formed to have a donut-like planar shape as a whole, and is also formed to have a wedge-like side surface shape as a whole. The adjacent surface on the casing 1 side consists of a first seat surface section 40 and a second seat surface section 41 having a different angle from the first seat surface section 40.
The abutment surface is formed into an inclined surface with an angle larger than the inclination angle of the first seat surface portion 41, and is a smooth surface portion 42 on which the shoe 32 slides. Further, a ball hole is formed at the boundary line between the first seat surface part 40 and the second seat surface part 41, and a ball hole is formed in the inner wall of the casing 1 at a position corresponding to this ball hole. A ball is held between the ball hole (not shown) and a ball hole (not shown). Therefore, when the auxiliary shoe 16 adjacent to the upper end of the first seat surface moves to separate the first seat surface 40 from the inner wall of the casing 1, the swash plate 4 rotates at a constant angle about the ball. . That is, when the hydraulic pressure is not acting on the auxiliary plunger 15 in the auxiliary cylinder 14, in other words, when the piston chamber 53b is at low pressure in FIG.
The pressing device supports the swash plate 4 with only the first seat surface 40 always in contact with the inner wall of the cylinder 1, and the motor is driven at a low speed.

However, when pressurized oil is fed into the auxiliary cylinder 14 and the auxiliary plunger 15 is moved, the first seat surface portion 40 of the swash plate 4 is separated from the inner wall of the cylinder 1 and is replaced by the swash plate 4. The second seat surface portion 41 is in contact with and supported by the inner wall of the cylinder 1, and the motor is driven at high speed.

The hydraulic motor A configured as described above operates as follows.

First, the engine is operated to send pressurized oil from the oil pump to the suction oil passage 11 via the outgoing path.
This pressurized oil passes through a suction groove communicating with the suction oil passage 11 and is sent into the port 33 located above this suction groove. Since this port 33 communicates with the cylinder 30, oil enters into the cylinder 30. When oil enters the cylinder 30, the plunger 31 tends to retreat. However, the shoe 32 fitted to the tip of the plunger 31 is in contact with the first seat surface portion 42 of the adjacent swash plate 4, and its movement acting perpendicularly to the smooth surface portion 42 is restricted and the movement in the lateral direction is restricted. In other words, only a secondary movement is induced in the smooth surface portion 42. Therefore, as the plunger 31 retreats, the cylinder block 3
will rotate.

Since the above-mentioned operations are performed in the plurality of cylinders 30, the cylinder block 3 rotates, and the output shaft 2 connected thereto is rotationally driven.

The first seat surface portion 40 of the swash plate 4 is connected to the casing 1
If the swash plate 4 is in surface contact with the inner wall of the
The rotation of the output shaft 2 is slower than when the second seat surface portion 41 is supported in surface contact with the inner wall of the casing 1. The tilting operation of the swash plate 4 has been described above, but the auxiliary plunger 15
That is, the auxiliary shoe 16 is not always pressed against the first seat surface portion 40 of the swash plate 4. When there is no pressure in the auxiliary cylinder 14, the first seat surface portion 40 of the swash plate 4 is in surface contact exclusively with the inner wall of the casing 1, so no thrust is required from the auxiliary plunger 15 at this stage. . Further, when the inside of the auxiliary cylinder 14 is pressurized, the second seat surface portion 41 of the swash plate 4
Since the plunger 15 comes into surface contact not only with the inner wall of the casing 1 but also with the inner wall of the casing 1, the thrust of the plunger 15 does not need to be large.

Next, the relationship between the counterbalance valve 60, pilot control valve 62, and motor will be explained.
The same symbols as in FIG. 1 are used.

The counterbalance valve 60 is built into a body 60a fixed to the side of the casing 1. That is, as shown in FIGS. 3 and 4, the body 60a is formed with circuits 58a and 59a that communicate with the pump side, and these circuits 58a and 59a communicate with the valve hole 73. The valve body of the counterbalance valve 60 is slidably inserted, and the valve hole 73 is in contact with drive circuits 58, 59 connected to the passages 11, 12 in FIG.
9 communicates with the hydraulic motor 51 side, the relief valve 70 side, and the check valves 67 and 68, respectively. For example, a portion of the pressure oil led to the circuit 58a is led to the right end of the counter balance valve 60 via the pilot circuit 58a' and the orifice 58b,
This pressure oil causes the counterbalance valve 60 to move to the left, and some of the pressure oil pushes open the check valve 60b from the passage 60b inside the counterbalance valve 60 and is led to the drive circuit 58.

Next, a body 62a incorporating a pilot control valve 62 is fixed to the side of the body 60a, and a valve hole serving as a circuit 64 is provided in the center of the body 62a.
Also, circuits 65 and 66 communicate with this valve hole 64 in the lateral direction.
The circuits 65 and 66 are connected to the circuits 58 and 59 in FIGS. 1 and 3 via a pair of left and right check valves 67 and 68 and ports 58' and 59', respectively.
are familiar with each.

A spool 74 of the pilot control valve 62 is slidably inserted into the valve hole serving as the circuit 64, and a pilot control circuit 50 shown in FIG. 2 is inserted into one end of the valve hole 64.
A port 50a leading to the chamber 75 is provided at the other end.
This chamber 75 is connected to the low pressure circuit 71 shown in FIG. 2 via a port 75a provided on the side of the body 62a. Furthermore, approximately the middle of the valve hole 64 is connected to the circuit 61 in FIG. 1, or in other words, the oil path 13 in FIG. As the port 61a slides, the port 61a selectively communicates with the port 75a via the valve hole 64 or the passage 76 in the spool 75.

For example, when driving at high speed, if pilot pressure is applied to the port 50a from the pilot control circuit 63 to push in the spool 74 and high-pressure oil is introduced into the circuit 58, the check valve 68 is pushed open from the pressure oil port 58'. Circuit 66-valve hole 64-
Pressure oil is introduced into the passage 13 in FIG. 2, ie, the circuit 61 in FIG. 1, through the orifice 61b and the port 61a.

Conversely, port 50a is connected to circuit 5 in Figure 1 on the tank side.
0, the spool 74 is pushed by the spring 77, so the port 61a is connected to the passage 76, so that the pressure oil in the passage 13 is connected to the circuit 61-port 61a-passage 76-port 75a.
- returned to tank 57 via circuits 71, 71a;

According to the present invention, a drive circuit, a circuit that connects the drive circuit and the pilot control valve, and a circuit that connects the pilot control valve and the swash plate control cylinder are provided within the body and within the body and the casing. As a result, each circuit becomes short and compact, the circuit resistance is reduced, and the entire circuit can be miniaturized, which is a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a control device according to an embodiment of the present invention, FIG. 2 is a partially sectional front view of a variable hydraulic motor according to the present invention, and FIG. 3 is a partial side view taken along the line - in FIG. 2. Figure 4 is a side view of the pilot control valve, Figure 5 is a bottom view taken along the - line, and Figure 6 is a side view of the pilot control valve.
It is a vertical front view taken along the line - in the figure. 13... Oil path, 15... Hydraulic motor, 52...
Swash plate, 53... Swash plate control cylinder, 55... High speed/low speed control switching valve, 56... Pump, 5
7... Tank, 58, 59... Drive circuit, 58
a, 59a...Oil supply and discharge circuit, 60...Counter balance valve, 60a, 62a...Body, 6
2...Pilot control valve, 64...Circuit, 7
1,71a...Low voltage circuit, 72...Swivel joint.

Claims (1)

[Claims] 1 A hydraulic motor drive circuit is selectively connected to the pump or tank via a switching control valve, and a swash plate control cylinder that controls the swash plate tilt angle of the hydraulic motor is connected to the drive circuit or low pressure via a pilot control valve. In a hydraulic motor, the casing and the body attached to the casing are selectively connected to the circuit and the pilot control circuit for switching and controlling the pilot control valve is selectively connected to the pump or tank via the high-speed/low-speed control switching valve. A swash plate, a cylinder block, a swash plate control cylinder, and an output shaft protruding outward are provided in the casing, a pilot control valve is provided in the body, and the body is located on the opposite side of the output shaft. A circuit for connecting the drive circuit and the pilot control valve is provided in the body, and a circuit for connecting the pilot control valve and the swash plate control cylinder is formed in the casing and the body. variable hydraulic motor.