JP2557283Y2 - 2 speed hydraulic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an improvement of a swash plate type hydraulic motor having a two-step tilt angle switching function of large and small.

(Prior Art) There is known a two-speed hydraulic motor in which the tilt angle of a swash plate can be switched between large and small by hydraulic pressure (Japanese Patent Application Laid-Open No. SHO 61-61).
-49175).

As shown in FIG. 5, the cylinder block 9 is housed in a storage space 12 formed inside the body 10 so as to be freely rotatable around the output shaft 9a, and is projected from the cylinder block 9 so as to slide freely in the axial direction. The base ends of the plurality of pistons 8 are brought into sliding contact with the swash plate 7 via the shoes 11, and the swash plate 7 is supported by the body 10 via the hydraulic drive mechanism 5 shown in FIG.

Pressure oil is supplied to the cylinder 6 in the cylinder block 9 accommodating each piston 8 in accordance with the rotational position, and the piston 8 expands and contracts by this pressure oil, and moves relative to the swash plate 7 to output together with the cylinder block 9. The shaft 9a is rotated. This direction of rotation is controlled by a switching valve 2 that switches according to the pressure of ports P ₁ and P ₂ formed in body 10.

The hydraulic drive mechanism 5 drives the swash plate 7 with the pressure oil supplied through the switching valve 21 and switches the support angle of the swash plate 7, that is, the tilt angle, to two levels of large and small, so that the cylinder block 9 Change the number of rotations.

(Problem of the Invention) In this case, the tilt angle is reduced to reduce the cylinder block 9.
When is rotated at a high speed, the frictional heat of the sliding contact portion between the shoe 11 and the swash plate 7 increases, and the temperature in the storage space 12 tends to increase.

In the sliding portion between the shoe 11 and the swash plate 7, a part of the hydraulic oil in the cylinder 6 passes through the shoe 11 for lubrication.
When the temperature of the storage space 12 rises excessively, the oil film breaks due to a decrease in the viscosity of the hydraulic oil, and the sliding portion is seized.
Such an increase in the temperature of the storage space 12 is not preferable because there is a possibility that a problem such as a reduction in the life of the bearing 13 to be supported may occur.

The present invention has been made to solve the above-described problem in the two-speed hydraulic motor, and has as its object to suppress a rise in temperature in the storage space.

(Means for Solving the Problems) The present invention provides a cylinder block rotatably supported in a storage space inside a body, and a piston protruding from the cylinder block so as to slide freely at a base end thereof in parallel with a rotation axis. ,
In a two-speed hydraulic motor including a swash plate that is in sliding contact with the base end of the piston and a hydraulic drive member that supports the swash plate by switching between two large and small tilt angles, a drain that communicates the storage space with a tank; A switching valve for selectively guiding high pressure and low pressure from a motor drive circuit to a hydraulic drive member, a passage for guiding pilot pressure from a pilot port to the storage space through a throttle, and a pilot pressure for the pilot port at the pilot port. And a spool for opening and closing the throttle passage, and a part of the hydraulic oil is introduced from the pilot port into the storage space as the hydraulic drive member switches the swash plate to a small tilt angle.

(Operation) When the tilt angle of the swash plate is small, the cylinder block rotates at high speed, and the generation of frictional heat at the sliding contact portion between the piston and the swash plate and at the support portion of the cylinder block increases. A part of the hydraulic oil is introduced into the storage space from the pilot port to the storage space while being adjusted to an appropriate amount via a throttle passage, and the drain collects the hydraulic oil into the tank so that the hydraulic oil circulates between the storage space and the tank. In addition, the heat generated in the storage space is released to the outside, and the temperature inside the storage space is suppressed from becoming high.

(Embodiment) FIGS. 1 to 4 show an embodiment of the present invention.

In FIG. 1, 1 is a main body of a two-speed hydraulic motor,
Switching valve 2 connected to ports P ₁ and P ₂ formed in body 10
And a hydraulic drive mechanism 5 for switching the tilt angle of the swash plate 7 between two levels, large and small.

The switching valve 2 is interposed between the ports P ₁ and P ₂ and the motor main body 1, and switches between the ports P ₁ and P _{2 according} to the pressure supplied from the hydraulic supply device of another unit. The hydraulic oil of P ₁ (P ₂ ) is supplied to the motor body 1, the motor body 1 is driven to rotate, and then discharged to the port P ₂ (P ₁ ) on the low pressure side. When the pressure difference of relief valve 14 and 15 ports P ₁ and P ₂ is greater than a predetermined one in which the motor body 1 bypassing relieve some of the pressure to the low pressure side.

The motor body 1 is provided with a brake 4 for holding a stopped state. Brake cylinder 26 that drives brake 4
Is selectively connected to the port P ₁ (P ₂ ) and the drain port T formed in the body 10 via the switching valve 2, and the switching valve 2
Is in either the forward or reverse rotation position of the motor body 1,
The hydraulic oil on the high pressure side is guided to the brake cylinder 26 to keep the brake 4 in the released state. When the switching valve 2 is switched to the stop position, the brake cylinder 26 is released to the drain port T to turn the brake 4 on.

On the other hand, the hydraulic drive mechanism 5 is selectively connected to the drive circuit of the motor body 1 and the drain port T via the switching valve 3.

As shown in FIGS. 2 and 3, the switching valve 3 accommodates a spool 17 inside the body 10 so as to be freely slidable and supports one end with a spring 18 while supporting the opposite end with the body 10. Facing the outer periphery of the spool 17, the body 10 has ports M ₁ and M ₂ communicating with the drive circuit of the motor body 1, and a port 24 leading to the hydraulic drive mechanism 5. And 25 are formed. In addition, a drain 19 communicating with the drain port T is formed in the spool 17.

Spool 17 is port at low pressure of pilot port Ps
Communicates 24 and 25 to the drain 19, when the high pressure of the pilot port Ps is against the spring 18 as shown in FIG. 3 slides in the body 10, connects the port 24 and 25 to ports M ₁ and M ₂ I do.

Further, a port 28 is formed in the body 10 in the vicinity of the end of the spool 17 on the pilot port Ps side. This port 28 is connected to the storage space 12 through a throttle 29 as shown in FIG.
To the spool 17 when the pilot port Ps is at low pressure.
And the spool 17 slides due to the high pressure of the pilot port Ps, thereby communicating with the pilot port Ps. On the other hand, between the storage space 12 and the drain T, the storage space 12
A drain 30 is provided to release the pressure from the tank. The supply of the pilot pressure to the pilot port Ps is performed by a supply device of another unit.

 Next, the operation will be described.

In the state shown in FIG. 1, the hydraulic motor is stopped, the brake cylinder 26 is released to the drain port T, and the brake 4 holds the motor body 1 in a stopped state.

When high pressure is supplied to the port P ₁ (P ₂ ) from this state, the switching valve 2 is switched to the left (right) section by the pilot pressure, pressure oil is supplied to the brake cylinder 26, and the brake 4 is released. Is done. At the same time, port P ₁ (P ₂ )
The hydraulic motor starts operating by the pressure oil supplied from the controller.

In this case, if pilot port Ps is low pressure, spool
Since 17 is in the position shown in FIG. 2 and ports 24 and 25 are open to the drain port T, the hydraulic drive mechanism 5 supports the swash plate 7 at a large tilt angle, and the hydraulic motor operates at low speed and high torque. Be driven. In this state, the port 28 is closed by the spool 17, and the storage space 12 communicates only with the drain port T.

On the other hand, when the pilot pressure is supplied to the pilot port Ps, the spool 17 slides to the position of Figure 3 against the spring 18, the port M ₁ and M ₂ are connected to the port 24 and 25. This allows the port to be driven according to the direction of rotation of the hydraulic motor.
High pressure of the drive circuit is supplied to one of 24 and 25, and the hydraulic drive mechanism 5 moves the swash plate 7 by this high pressure and supports it at a small tilt angle. As a result, the hydraulic motor has a small capacity and rotates at a high speed.

At the same time, the port 28 communicates with the pilot port Ps, and a part of the pilot oil is supplied to the storage space 12 of the motor body 1 little by little through the throttle 29. Meanwhile, storage space 12
Is released to the tank via the drain 30, and as a result, a constant amount of hydraulic oil circulates between the storage space 10 and the tank during high-speed rotation of the hydraulic motor.

Then, the hydraulic oil releases frictional heat generated by a sliding portion between the swash plate 7 and the piston and a bearing that supports the cylinder block to the outside of the body 10, so that the temperature in the storage space 12 does not excessively increase. In addition, long-time high-speed operation can be performed without worrying about seizure of the sliding contact portion.

When the pressure of the pilot port Ps is reduced, the switching valve 3 is switched again, and the hydraulic drive mechanism 5 increases the tilt angle of the swash plate 7 and closes the port 28 to supply hydraulic oil to the storage space 12. Also stop.

(Effects of the Invention) As described above, the present invention provides a drain port that communicates a storage space with a tank, a switching valve that selectively guides high pressure and low pressure from a motor driving circuit to a hydraulic drive member, A hydraulic pressure drive member switches the swash plate to a small tilt angle by providing a passage for guiding the pilot pressure to the storage space through the throttle and a spool for switching the switching valve according to the pilot pressure of the pilot port and opening and closing the throttle passage. A part of the hydraulic oil was introduced from the pilot port into the storage space along with the above, so when the tilt angle was reduced and the rotation speed increased, a certain amount of hydraulic oil was transferred between the storage space and the tank. There is no danger that the sliding member in the storage space circulates and seizure occurs, and the durability of the two-speed hydraulic motor is improved. Also, since the hydraulic oil to the storage space is made not from the motor drive circuit but from the pilot port,
By adjusting the throttle of the pilot passage, an appropriate amount of hydraulic oil required for cooling the storage space can flow.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a two-speed hydraulic motor showing an embodiment of the present invention, FIGS. 2 and 3 are longitudinal sectional views showing the structure of a switching valve, and FIG. FIG. FIG. 5 is a longitudinal sectional view of a two-speed hydraulic motor showing a conventional example, and FIG. 6 is a hydraulic circuit diagram of the same. 1 ... motor body, 2,3 ... switching valve, 5 ... hydraulic drive mechanism, 7 ... swash plate, 10 ... body, 12 ... storage space, 17 ...
… Spool, 19,30 …… Drain, 24,25,28, M ₁ , M ₂ , P ₁ , P
₂ …… Port, Ps …… Pilot port, T …… Drain port.

Claims (1)

(57) [Scope of request for utility model registration] 1. A cylinder block rotatably supported in a storage space inside a body, a piston protruding from a base end of the cylinder block so as to slide freely in parallel with a rotation axis,
In a two-speed hydraulic motor including a swash plate that is in sliding contact with the base end of the piston and a hydraulic drive member that supports the swash plate by switching between two large and small tilt angles, a drain that communicates the storage space with a tank; A switching valve for selectively guiding high pressure and low pressure from a motor drive circuit to a hydraulic drive member, a passage for guiding pilot pressure from a pilot port to the storage space through a throttle, and a pilot pressure for the pilot port at the pilot port. And a spool that opens and closes the throttle passage and switches the swash plate to a small tilt angle so that a part of the hydraulic oil is introduced from the pilot port into the storage space as the hydraulic drive member switches the swash plate to a small tilt angle. A two-speed hydraulic motor characterized in that: