JPH054562Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a control device for a hydraulic motor suitable for a hydraulic circuit for driving or hoisting a construction machine such as a hydraulic excavator or a crawler crane.

[Conventional technology]

Various types of hydraulic motors have been used to drive construction machinery, but variable displacement hydraulic motors (hereinafter referred to as , abbreviated as hydraulic motor) are used. Hydraulic motors are usually
The amount of pressure oil supplied is controlled by changing the tilt angle of the swash plate etc. using a control cylinder built into the hydraulic motor to control the amount of liquid that can be sucked in and discharged in one rotation of the hydraulic motor. It is set so that the rotation speed (number of revolutions) can be controlled even if it is constant.

Methods for introducing the pressure applied to the control cylinder include a self-pressure method in which the driving pressure of the hydraulic motor is directly introduced, and a pilot pressure method using an external hydraulic pressure source.

Among these, when the drive pressure of the hydraulic motor is relatively high, a self-pressure method is desirable, since it can reliably control the control cylinder of the hydraulic motor and allows the external dimensions to be relatively small. An example of this self-pressure method is shown in the second
As shown in the figure. The hydraulic motor control device shown in FIG. 2 is disclosed as Utility Model Publication No. 59-7647.

In FIG. 2, the hydraulic motor control device includes a hydraulic motor 41 with a built-in control cylinder 42, a hydraulic pump 47 as a hydraulic pressure source connected to a hydraulic tank 46, a directional control valve 48, and a counter. Passages 54a, 54b connected to the hydraulic motor 41 via a balance valve 49 and a brake valve 51 consisting of reliefs 50a, 50b;
4b, and a selector valve 55 that switches the pressure oil supplied to the control cylinder 42 of the hydraulic motor 41 from the shuttle valve 52 provided between the hydraulic motor 4b.

With this configuration, when the vehicle is traveling downhill, the supply flow rate of the hydraulic pump 47 is small and the hydraulic motor 4
1 is driven by the weight of the vehicle and performs a pumping action, and even if the pressure in the passages 54a, 54b on the discharge side of the hydraulic motor 41 and the counterbalance valve 49 increases, the pressure in the passages 54a, 54b on the discharge side of the hydraulic motor 41 and the counterbalance valve 49 increases.
, whichever is higher, is introduced into the control cylinder 42 to cause the piston 53 in the control cylinder 42 to
By acting on the hydraulic motor 41, the control cylinder 42 becomes uncontrollable during descent, that is, the hydraulic motor 41
This has the effect of reliably eliminating inconveniences such as the inability to control the capacity of the system.

On the other hand, there is a hydraulic motor control device as shown in FIG. 3 that employs a pilot pressure system using an external hydraulic pressure source.

In FIG. 3, the hydraulic motor control device includes a variable displacement hydraulic motor (hereinafter referred to as a hydraulic motor) 11 as a variable displacement hydraulic motor having a built-in control cylinder 12, and a hydraulic tank as a hydraulic tank. Hydraulic pump 2 serves as a hydraulic pressure source for driving a motor that drives hydraulic motor 11 by sucking hydraulic oil from pump 1 and supplying it to hydraulic motor 11. Direction control valve 4 that controls the rotation direction of the motor 11
and a brake valve 10 consisting of a counterbalance valve 8 and a relief valve 9 provided in passages 5 and 6 connecting the directional control valve 4 and the hydraulic motor 11, and a brake valve 10 that sucks hydraulic oil from the hydraulic tank 1 and operates the selector valve 19. a hydraulic pump 24 as a hydraulic pressure source for supplying pilot pressure, which supplies pressure oil acting as pilot pressure to the control cylinder 12 of the hydraulic motor 11 via the hydraulic pump 24;
It is mainly composed of.

As described above, a brake is provided between the passages 5 and 6, which is comprised of a counterbalance valve 8 that generates back pressure to prevent the hydraulic motor 11 from running away, and a relief valve 9 that regulates the upper limit of the pressure. valve 10
A shuttle valve 7 is provided between the brake valve 10 and the direction control valve 4, and the shuttle valve 7 is connected to the cylinder 14a of the brake device 14 provided on the output shaft 13 of the hydraulic motor 11. A passage 15 communicating with is connected to the passage 15, and pressure oil can be selectively supplied to the brake device 14 from the passage 5 or the passage 6 via a pressure reducing valve 16 as a pressure reducing means provided in the passage 15.

The hydraulic pump 24 is configured to supply pressure oil to the A port 12a and the B port b of the control cylinder 12 via a selector valve 19 provided on the downstream side of the passage 22 and passages 20 and 21, respectively. By operating the selector valve 19, pressure oil is supplied to one side of the cylinder section partitioned by the piston 12c, and the other side is opened to the hydraulic tank 1. The stroke of 12c changes, thereby making it possible to change the capacity of the hydraulic motor 11.

Further, from the passage leading from the hydraulic pump 2 to the directional control valve 4, a passage including a pressure control valve 3 as a pressure setting means for regulating the upper limit of the pressure generated in the passages 5 and 6 branches off, and from the hydraulic pump 24 to the selector valve. 19
A pressure control valve 25 serving as pressure setting means for regulating the upper limit of the pressure of the pressure oil discharged from the hydraulic pump 24 branches off from the passage 22 leading to the hydraulic pump 24 . The discharge sides of the pressure control valves 3 and 25 are open to the hydraulic tank 1 together with the end of the direction control valve 4 on the side opposite to the hydraulic pump 2 connection side.

[Problem that the invention aims to solve]

By the way, in the case of a hydraulic motor control device using self-pressure as described above, the shuttle valve 52 and the selector valve 5 are connected to the control cylinder 42 of the hydraulic motor 41.
Since the self-pressure is directly guided through 5,
The pressure limits of the passages 55a and 55b leading from the shuttle valve 52 to the control cylinder 42 via the selector valve 55, the selector valve 55, the control cylinder 42, etc. must be the same as the pressure limit of the hydraulic motor 41.

In addition, when this hydraulic motor 41 is used as a traveling motor for a hydraulic excavator or the like, and when going down a slope, the selector valve 55 and the control cylinder 42 are
Since the pressure applied to the selector valve 55 and the control cylinder 42 fluctuates greatly as the number of load repetitions increases, it is necessary to ensure mechanical strength.
cannot be made compact.

On the other hand, in the method using pilot pressure, the force required to operate the control cylinder 12 is small when the pressure in the passage of the hydraulic motor 11 is low, and becomes large when the pressure in the passage is high. In order to operate the cylinder 12 reliably, the pilot pressure set by the pressure control valve 25 is always set high when the pressure in the passage of the hydraulic motor 11 is high, or the pilot pressure is controlled so that the cylinder 12 operates even at low pressure. It is necessary to increase the diameter of the cylinder 12.

However, when the pilot pressure is set high, the pressure guided to the control cylinder 12 is always constant, but the pressure oil discharged from the hydraulic pump 24 is constantly relieved from the pressure control valve 25 and returned to the hydraulic tank 1. Therefore, all of this pressure energy is lost, and there is a problem in that the energy loss is large.

On the other hand, if the cylinder diameter is increased, the hydraulic motor 11 becomes less organized, making it difficult to use as a shoe-in type travel motor.

In addition, in order to use this control device as a travel motor for a hydraulic shovel or the like, a pipe that leads pressure oil from the upper rotating body to the control cylinder 12 of the hydraulic motor 11 attached to the lower traveling body is connected to the selector valve 1.
9 on the upper revolving structure side, two are required, and the cost of the center joint provided at the J section, which is a part of the passages 20 and 21 connecting the selector valve 19 and the control cylinder 12 in FIG. 3, also increases. .

This idea was created in view of the above problems, and its purpose was to make a variable displacement hydraulic motor compact so that it could be mounted on the undercarriage as a shoe-in type travel motor. ,
Another object of the present invention is to provide a hydraulic motor control device that requires a minimum number of pipes led from the upper revolving structure to the lower traveling structure.

[Means for solving problems]

In order to solve the problems faced by the prior art and achieve the above objectives, this invention provides a variable displacement hydraulic motor with a built-in control cylinder that changes the displacement, and an output shaft of the variable displacement hydraulic motor. An attached brake device, a pilot pressure supply hydraulic pressure source for supplying pilot pressure fluid, a pressure setting means for setting the pilot pressure, and a pilot pressure fluid guided from the pilot pressure supply hydraulic pressure source to the control cylinder. a selector valve that switches the direction of the motor, a motor drive hydraulic pressure source that supplies pressure oil to drive the variable displacement hydraulic motor, and a hydraulic fluid that leads from this motor drive hydraulic pressure source to the variable displacement hydraulic motor. a directional control valve that switches the rotation direction of the variable displacement hydraulic motor by switching the supply direction of the variable displacement hydraulic motor, a shuttle valve provided downstream of the directional control valve, and a passage connecting the exit side passage of the shuttle valve and the brake device. A hydraulic motor control device comprising: a pressure reducing means provided in a pilot pressure supplying hydraulic pressure source; control cylinder control pressure selection means for guiding the higher pressure of the pressure fluid set by the pressure fluid and the pressure fluid supplied to the brake device from the motor drive fluid pressure source to the selector valve; The valve is configured to be switched depending on the level of pressure supplied to the selector valve.

[Effect]

With the above configuration, the pressure of the hydraulic fluid supplied from the motor drive hydraulic pressure source and set by the pressure reducing means is equal to the pressure supplied from the pilot pressure supply hydraulic pressure source and set by the pressure setting means. If the pressure is lower than the hydraulic pressure, the hydraulic pressure supplied from the pilot pressure supply hydraulic pressure source is supplied to the control cylinder of the hydraulic motor via the selector valve. In addition, if the pressure of the hydraulic fluid supplied from the motor drive hydraulic pressure source and set by the pressure reducing means is higher than the pressure of the hydraulic fluid supplied from the pilot pressure supply hydraulic pressure source, the motor drive hydraulic pressure Pressure fluid from a source is supplied to the control cylinder.

On the other hand, the selector valve switches depending on the pressure level set by the pilot pressure setting means, thereby switching the pressure guided to the control cylinder and making it possible to control the number of rotations (rotational speed) of the hydraulic motor. become.

〔Example〕

An embodiment of this invention will be described below based on the drawings.

FIG. 1 is a hydraulic circuit diagram of a hydraulic motor control device as a hydraulic motor control device according to an embodiment of this invention. In the following description, each component that is the same or can be considered to be the same as that of the conventional example shown in FIG. 3 is given the same reference numeral, and a description of each overlapping component is omitted.

In FIG. 1, the hydraulic motor control device according to the embodiment includes a passage 22 extending from a hydraulic pump 24 as a hydraulic pressure source for supplying pilot pressure to a selector valve 19 side.
and the passage 15 on the downstream side of the pressure reducing valve 16 are connected to the shuttle valve 3 as a control pressure selection means of the control cylinder 12.
1, the outlet side of the shuttle valve 31 and the inlet side of the selector valve 19 are connected, and a passage 32 branched from the passage 22 is connected as a pilot passage of the selector valve 19.
On the upstream side of the branch part 22b where 2 branches from the passage 22, a directional switching valve 34 is provided as a pressure setting means.
and two pressure control valves 35 and 36 whose outlet sides are open to the hydraulic tank 1 are branched into a passage 37.

The pressure control valves 35 and 36 respectively define the upper limit of the pressure of the pressure oil discharged from the hydraulic pump 24 according to the switching direction of the directional switching valve 34. In this embodiment, the pressure control valve 35 The set pressure of the pressure control valve 36 is set to about 50 kgf/cm ² , and the set pressure of the spring 33 as a switching means of the selector valve 19 is set to about 30 kgf/cm ² .
By setting the pressure to 40 Kgf/cm ² , when the higher pressure is selected by the directional control valve 34, the pilot pressure introduced overcomes the set pressure of the spring 33 and the selector valve 19 is switched from the normal position to the offset position. It is starting to change. All other parts have the same structure as the conventional example shown in FIG.

Next, a case will be described in which the hydraulic motor control device configured as described above is used as a traveling device for a vehicle such as a hydraulic excavator or a crawler crane.

<At the time of starting> First, in order to rotate the hydraulic motor 11, a prime mover (not shown) is started. When the prime mover is started, the hydraulic pumps 2 and 24 suck hydraulic oil from the hydraulic tank 1 and discharge pressure oil. At this time, since the directional control valve 4 is in the neutral position, the hydraulic pump 2
Pressure oil discharged from the directional control valve 4 forms a no-load circuit that returns to the hydraulic tank 1.

On the other hand, the pressure oil discharged from the hydraulic tank 24 is
Assuming that the directional control valve 34 attached to the passage 37 is in the normal position, the pressure oil at the pressure specified by the pressure control valve 35 is transferred to the control cylinder 12 via the shuttle valve 31, the selector valve 19, and the passage 20. Supplied to A port 12a, piston 12c
is driven in the direction in which the stroke becomes larger, that is, in the direction in which the capacity of the hydraulic motor 11 is increased and the hydraulic motor 11 is driven at low speed and high torque. Furthermore, when the directional control valve 34 is switched to the offset position, the pressure control valve 36
The higher pressure defined by
1 to the selector valve 19. At this time, higher pressure oil is introduced from the passage 32 to the pilot passage of the selector valve 19, and this pressure moves the selector valve 19 to the offset position. Switch. As a result, the pressure oil led from the shuttle valve 31 to the selector valve 19 is supplied from the passage 21 to the B port 12b of the control cylinder 12, and the piston 12c is moved in the direction where the stroke becomes smaller, that is, the capacity of the hydraulic motor 11 is reduced. and drive in the direction of high speed and low torque. In addition, in these cases, after supplying pressure oil into the control cylinder 12,
Pressure oil discharged from the hydraulic pump 24 returns to the hydraulic tank 1 through the pressure control valve 35 or 36.

Therefore, when the hydraulic pumps 2 and 24 are started with the directional control valves 4 and 34 in their normal positions, pressure oil is not supplied to the hydraulic motor 11, but pressure oil is supplied to the control cylinder 12 from the hydraulic pump 24 to the hydraulic motor 1.
Pressure oil will be supplied in a direction that increases the capacity of 1.

[At low pressure rotation (at small load)]

Now, when the directional switching valve 4 provided on the discharge side of the hydraulic pump 2 is operated in the above state to guide the pressure oil discharged from the hydraulic pump 2 to the passage 5, this pressure oil first flows from the shuttle valve 7. It reaches the brake device 14 through the passage 15 in which the pressure reducing valve 16 is interposed, and drives the piston in the cylinder 14a of the brake device 14 to release the brake. Further, the pressure oil discharged from the hydraulic pump 2 reaches the inlet of the hydraulic motor 11, moves the counterbalance valve 8 to rotate the hydraulic motor 11, and furthermore, the pressure oil is attached to the tip of the output shaft 13 (not shown). Rotate the sprocket. At this time, if the pressure in the passage 15 on the downstream side of the pressure reducing valve 16 is lower than the pressure in the passage 22, the pressure oil at the pressure specified by the pressure control valve 35 is controlled from the A port 12a as described above. It is guided to the cylinder 12, increases the capacity of the hydraulic motor 11, and maintains this state. This causes the hydraulic motor 11 to rotate at low speed and high torque.

When the directional control valve 34 is operated from this state to switch to the offset position, the hydraulic pump 2
The pressure oil discharged from 4 is guided to the shuttle valve 31 and the selector valve 19 with its pressure regulated by the pressure control valve 36. At this time, since the pressure regulated by the pressure control valve 36 is higher than the pressure regulated by the pressure control valve 35, the shuttle valve 3
1 naturally selects the pressure oil discharged from the hydraulic pump 24 and guides it to the selector valve 19. On the other hand, the pressure control valve 36, which is higher than the set pressure of the spring 33, is connected to the pilot passage 32 of the selector valve 19, as described above.
Since the pressure defined by
This time, it is guided from the passage 21 to the B port 12b of the control cylinder 12. As a result, the piston 12c
moves toward decreasing capacity and the hydraulic motor 11
Reduce the capacity of and maintain this state. As a result, the rotational speed of the hydraulic motor 11 increases.

[During high pressure rotation (during heavy load)] The directional control valve 34 provided in the passage 37 is in the normal position, and the pressure from the passages 5 and 6 is lower than the pressure in the passage 22 defined by the pressure control valves 35 and 36. When the pressure of the pressure oil guided to the brake device via the pressure reducing valve 16 is higher, the shuttle valve 31 selects the pressure oil guided from the pressure reducing valve 16 to the brake device 14 and guides it to the selector valve 19. The hydraulic motor 11 is led to the A port 12a of the control cylinder 12 through the passage 20, thereby increasing the capacity of the hydraulic motor 11 and reducing the rotation speed.

From this state, when the directional control valve 34 is switched to the offset position, the selector valve 19 is also switched to the offset position for the reason described above, and the pressure oil led from the pressure reducing valve 16 is then transferred to the control cylinder 12 via the passage 21. It is supplied to the B port 12b.
As a result, the capacity of the hydraulic motor 11 is reduced and the number of revolutions is increased.

With the above configuration, when used as a traveling motor for construction machinery such as a hydraulic excavator, the hydraulic pump 24 installed on the upper revolving body is connected to the control cylinder 12 of the hydraulic motor 11 attached to the lower traveling body. In order to send pressure oil, the passage 2 between the branch part 22a of the passage 37 and the branch part 22b of the passage 32 is
If you pass the center joint J at the 0 position, there will be one passage through the center joint J, so
The structure of the center joint J is simplified and costs can be reduced.

Although this embodiment is explained using a hydraulic circuit used in a traveling device of a construction machine, it goes without saying that the present invention can be applied to all other hydraulic circuits based on the same principle.

In addition, when the response speed of the control cylinder 12 may be slow, the passage 2 on the discharge side of the hydraulic pump 24
The directional switching valve 34 branched from 2 is omitted, and one of the pressure control valves 35 and 36 is omitted, resulting in a structure similar to that of the conventional pressure control valve 25 shown in FIG. It goes without saying that similar switching control is possible by controlling the set pressure of the pressure control valve so that the low pressure side is lower than the set pressure of the selector valve 19 and the high pressure side is higher than the set pressure. do not have.

As described above, according to the above embodiment, the pressure guided to the control cylinder 12 is controlled by the pressure control valve 3 which is provided with the low pressure side branched to the discharge side of the hydraulic pump 24.
The control cylinder 12 can receive a constant range of pressure oil that is necessary and sufficient for controlling the hydraulic motor 11, and as a result, a compact structure suitable for the characteristics of the hydraulic motor 11 can be achieved. Therefore, it can be constructed with dimensions sufficient to be mounted on the running body of a shoe-in type construction machine. In addition, the passage passing through center joint J will be
It can be composed of books.

[Effect of idea]

As is clear from the previous explanation, the higher pressure of the pressure fluid supplied to the selector valve from the pilot pressure supply fluid pressure source and the pressure fluid supplied to the brake device from the motor drive fluid pressure source. control pressure selection means for a control cylinder that guides the pressure fluid to the selector valve;
According to this invention, in which the selector valve is switched according to the pressure set by the pressure setting means for setting the pilot pressure, the control pressure supplied to the control cylinder via the selector valve is controlled within a certain range. Since sufficient control pressure can be supplied to the control cylinder under the conditions specified by A cylinder can be constructed. Moreover, this makes it easy to mount the motor on the lower traveling body as a shoe-in type traveling motor of a construction machine. Furthermore, since the passage leading from the upper revolving structure to the lower traveling structure can be configured with one passage, the center joint can be simplified and costs can also be reduced.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram of a hydraulic motor control device according to an embodiment of this invention, Fig. 2 is a hydraulic circuit diagram of a hydraulic motor control device according to a conventional example, and Fig. 3 is a hydraulic circuit diagram of a hydraulic motor control device according to a conventional example. FIG. 3 is a hydraulic circuit diagram of the control device. 1...Hydraulic tank, 2...Hydraulic pump, 4...
Directional switching valve, 5, 6... Passage, 7... Shuttle valve, 8... Counter balance valve, 9... Relief valve, 10... Brake valve, 11... Hydraulic motor,
12... Control cylinder, 13... Output shaft, 14...
... Brake device, 15 ... Passage, 16 ... Pressure reducing valve, 19 ... Selector valve, 20, 21, 22 ...
Passage, 31... Shuttle valve, 32... Passage, 33
... Spring, 34 ... Directional switching valve, 35, 36 ...
Pressure control valve, 37...passage.

Claims (1)

[Scope of utility model registration request] A variable displacement hydraulic motor having a built-in control cylinder that varies the displacement, a brake device attached to the output shaft of the variable displacement hydraulic motor, and a hydraulic pressure source for supplying pilot pressure to supply pilot pressure fluid. , a pressure setting means for setting the pilot pressure, a selector valve for switching the direction of the pilot pressure fluid guided from the pilot pressure supply hydraulic pressure source to the control cylinder, and a pressure oil for driving the variable displacement hydraulic motor. A directional control valve that switches the direction of rotation of the variable displacement hydraulic motor by switching the supply direction of the pressure fluid guided from the motor driving hydraulic pressure source to the variable displacement hydraulic motor. , a hydraulic motor control device comprising: a shuttle valve provided on the downstream side of the directional control valve; and a pressure reducing means provided in a passage connecting an outlet side passage of the shuttle valve and a brake device; A pressure setting means that can switch the pressure set by the hydraulic pressure source into two levels, pressure fluid set by the pilot pressure supply hydraulic pressure source, and pressure supplied to the brake device from the motor drive hydraulic pressure source. and control pressure selection means for a control cylinder that guides a higher pressure liquid among the liquids to the selector valve, and the selector valve can be switched depending on the level of pressure supplied to the selector valve. Hydraulic motor control device.