JPH0724642Y2 - Hydraulic motor capacity controller - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention uses a hydraulic motor used for general machinery, construction machinery, etc. as a 2nd speed motor by controlling switching to the 2nd speed, and if necessary, increases the capacity. The present invention relates to a displacement control device for a hydraulic motor that is fixed and can be used even with a fixed motor.

[Conventional technology]

Normally, as the hydraulic motor used for the construction machine or the like, a fixed motor having a fixed motor capacity according to the design specifications of the construction machine is selected. However, depending on the actual operating conditions, there are times when it is desired to obtain high torque because it may be low speed, and conversely, where it is desirable to obtain high speed because low torque may be used. In such a case, there is a problem that the function is limited in the case of the fixed motor.

Therefore, in order to effectively exert the function of the hydraulic motor within the limited output horsepower range, the hydraulic motor may be switched to the second speed and used.

For example, considering a traveling motor for a construction machine, in the case of frequent flatland traveling, there is a demand for high-speed traveling although the torque may be low. In this case, the hydraulic motor must have a small capacity to rotate at high speed. Correspond. On the other hand, when climbing a slope or loading cargo, there is a demand that the traveling speed be slow but a large torque is required. In this case, the hydraulic motor may be switched to a large capacity to cope with the demand.

Conventionally, as a displacement control device for such a hydraulic motor, those shown in FIGS. 5 and 6 are known.

First, in FIG. 5, reference numeral 1 denotes a variable displacement type hydraulic motor. As the hydraulic motor 1, for example, a swash shaft type, a swash plate type or a radial piston type hydraulic motor is used. The motor capacity can be changed by displacing the portion 1A. 2A and 2B are hydraulic pipes for supplying pressure oil to the hydraulic motor 1, and the hydraulic pipes 2A and 2B are connected to a hydraulic source (neither is shown) via a brake device and a direction switching valve. Reference numeral 3 is a high-pressure selection valve that selects the high-pressure side of the hydraulic pipes 2A and 2B, and the drive pressure derived by the high-pressure selection valve 3 is input to a capacity control device 4 described later.

Reference numeral 4 denotes a displacement control device attached to the hydraulic motor 1. The displacement control device 4 has a casing 4A and one end side slidably provided in the casing 4A, and the other end side protrudes out of the casing 4A. It is composed of a control piston 4B connected to the variable volume portion 1A, and a large oil chamber 4C and a small oil chamber 4D defined in the casing 1A by the control piston 4B.

Reference numeral 5 is a pressure introducing pipe that connects between the high pressure selection valve 3 and the capacity control device 4, and 6 is a control valve which is provided in the middle of the pressure introducing pipe 5 and includes a 4-port 2-position switching valve. 6
Drive pressure to the small oil chamber
Driven by introducing to 4D and connecting the large oil chamber 4C to the tank 7 and setting the control piston 4B in the reduction direction shown in the drawing to switch the motor capacity to a small capacity and the control valve 6 to the switching position (b). The pressure is introduced into the large oil chamber 4C, and the small oil chamber 4D is connected to the tank 7 so that the control piston 4B is extended and the motor capacity is increased.

The displacement control device of the hydraulic motor configured as described above switches the control valve 6 based on the pilot pressure as a hydraulic pressure command output from a switching valve (not shown) on the cab side to control the displacement control device 4. By expanding and contracting the piston 4B,
The capacity of the hydraulic motor 1 can be switched in two steps, and the characteristics shown in FIG. 6 are obtained.

[Problems to be solved by the device]

However, the above-mentioned conventional technique is not applicable to the hydraulic motor 1
In addition to the capacity varying section 1A, the capacity control device 4 and the control valve 6 need to be integrally incorporated, which causes a problem that the number of parts increases and the size increases. In particular, when the hydraulic motor 1 is a traveling motor for a track-type construction machine, the traveling motor protrudes in the width direction from between the shoes of the crawler track as a result of an increase in shape and size, and a so-called "in-shoe" occurs. There is a problem that it cannot be achieved.

The present invention has been made in view of the above problems of the prior art. The hydraulic motor can be automatically switched to the second speed, and can be used as a fixed motor by fixing it to a large capacity or a small capacity as needed, and further controlling it. It is an object of the present invention to provide a displacement control device for a hydraulic motor that does not require a valve or the like and can make the second-speed motor as small as a fixed motor.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention defines a casing having a cylinder inside and one end side slidably provided in the cylinder of the casing, and defining the inside of the casing into a large oil chamber and a small oil chamber. At the same time, the other end of the control piston protrudes into the casing and is connected to the variable capacity portion of the hydraulic motor, the spool is slidably provided in the spool cylinder formed in the control piston, and A spool annular chamber that is defined in the spool cylinder and that is formed in the axial middle of the spool and that is in constant communication with the small oil chamber; a spool end chamber formed at one end and a spring chamber formed at the other end. A spring provided in the spring chamber for constantly urging the spool toward the spool end chamber, and a pressure introducing port for introducing the driving pressure of the hydraulic motor into the small oil chamber. A switching port formed on the control piston for selectively communicating the large oil chamber with either the spring chamber or the spool annular chamber by sliding the spool; and the spool end chamber outside the casing or the control piston. One communication port for communication, a switching valve for switching and connecting the one communication port to a hydraulic power source and a drain, another communication port for communicating the spring chamber outside the casing or the control piston, and the other communication port And a drain that is always connected.

[Action]

With the above structure, if the switching valve is connected to the drain side, the spool end chamber communicates with the drain.Therefore, the spool slides toward the spool end chamber side by the spring, and if the switching valve is connected to the hydraulic pressure source side, the spool end chamber is connected. Since the partial chamber communicates with the hydraulic power source, the spool comes to slide against the spring toward the spring chamber,
As a result, the large oil chamber is selectively communicated with the spring chamber and the spool annular chamber via the switching port, and the control piston slides in the casing due to the difference in oil pressure between the large oil chamber and the small oil chamber. Therefore, the capacity of the hydraulic motor can be appropriately switched and controlled between a large capacity and a small capacity.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4. The same components as those of the conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

1 to 3 show a first embodiment of the present invention.

In the figure, 11 is a casing of this embodiment, which is composed of a casing body 12 having one end opened and the other end serving as a bottom portion, and a lid body 13 closing the one end side opening of the casing body 12. A cylinder 14 is formed in the casing body 12 in the axial direction, and a rod insertion hole 15 is formed in the bottom.

Reference numeral 16 denotes a control piston formed in a stepped cylindrical shape having a bottom, and the control piston 16 has a piston portion 16A as a large diameter portion slidably inserted into the cylinder 14 at one end side and a rod insertion hole 1
The other end side is integrally formed with a rod portion 16B as a small diameter portion protruding outside the casing body 12 via 5, and the piston portion 16A allows the inside of the cylinder 14 to move into the large oil chamber A on the lid 13 side.
And a small oil chamber B on the bottom side, and the rod portion 16B is connected to the variable capacity portion 1A of the hydraulic motor 1. The control piston 16 has an opening 17A at one end and a bottom 17B at the other end to form a spool cylinder 17 in the axial direction, and the opening 17A at the one end is closed by a plug 18.

Reference numeral 19 denotes a spool slidably provided in the spool cylinder 17, and the spool 19 has two lands in the axial direction.
19A and 19B are formed separately, and one land 19A and plug
A spool end chamber C is defined between the land 18 and the land 19A,
A spool annular chamber D is defined between 19B and the other land 1
A spring chamber E is formed between 9B and the bottom portion 17B of the spool cylinder 17. Reference numeral 20 is a compression spring provided in the spring chamber E, and the compression spring 20 is arranged between the bottom portion 17B of the spool cylinder 17 and the land 19B of the spool 19 and
9 is always biased to the right as indicated by the arrow X, and is kept in the illustrated state.

Reference numeral 21 is a pressure introducing port formed near the bottom of the casing body 12, and the pressure introducing port 21 is connected to the high pressure selection valve 3 via a pressure introducing pipe 5. 22 is the control piston 16
Is a communication port obliquely formed in the piston portion 16A, the communication port 22 constantly communicates between the small oil chamber B and the spool annular chamber D, and introduces a driving pressure into the spool annular chamber D. Has become.

A switching port 23 is formed in the piston portion 16A of the control piston 16, and the switching port 23 communicates with the large oil chamber A via a communication passage 24 formed in the axial direction of the piston portion 16A. When the pilot pressure acting on the spool end chamber C is low and the spool 19 is displaced by the compression spring 20 in the X direction shown by the arrow, the switching port 23 opens to the spring chamber E and becomes large. The oil chamber A is communicated with the oil chamber A, and the spool 19 is blocked from the spool annular chamber D by the land 19B of the spool 19. Also, the pilot pressure increases and the spool
When 19 is displaced in the Y direction shown by the arrow, the switching port 23 is opened in the spool annular chamber D and communicates with the large oil chamber A, and the land 19B of the spool 19 causes the switching port 23 to communicate with the spring chamber E. Be cut off.

25 is a circumferential groove formed on the outer circumference of the piston portion 16A of the control piston 16 positioned closer to the lid 13 than the switching port 23, and 26 is a piston portion 16A for communicating the spool end chamber C with the circumferential groove 25.
A communication port 27 is formed on the peripheral groove 25 of the switching valve 31 which will be described later.
One communication port is provided in the casing body 12 so as to communicate with the casing body 12, and the communication port 27 is a pilot pipe described later.
It is connected to 33 and is adapted to introduce pilot pressure into the spool end chamber C. On the other hand, 28 is the casing body 12
A circumferential groove formed on the inner circumferential surface of the rod insertion hole 15 of the control piston 16 and a rod groove 16 of the control piston 16 for communicating the spring chamber E with the circumferential groove 28.
A communication port 30 bored in B is another communication port 30 bored in the casing body 12 so as to communicate the circumferential groove 28 with the tank 7. The communication port 30 is always connected to the tank 7 for control. The spring chamber E is always connected to the tank 7 regardless of the displacement state of the piston 16.

Further, 31 is a 3-port 2-position switching valve provided in, for example, an operator's cab, the inflow side of the switching valve 31 is connected to the external hydraulic power source 32 and the tank 7, and the outflow side is connected via a pilot pipe 33. It is connected to port 27. Then, by setting the switching valve 31 to the switching position (C), the spool end portion C communicates with the tank 7 and to the switching position (D),
The spool end chamber C communicates with the hydraulic power source 32.

The present embodiment is configured in this way, and its operation will be described next.

First, when the switching valve 31 is switched to the switching position (C),
The spool 19 slides in the direction of the arrow X by the spring 20 to the position where it abuts the plug 18 as shown in the drawing, and the switching port 23 communicates with the spring chamber E to keep the large oil chamber A in the tank pressure state. Since the driving pressure of the hydraulic motor 1 is introduced into the small oil chamber B, the control piston 16 is displaced in the arrow X direction by the driving pressure introduced into the small oil chamber B, and the motor capacity is small. Is set to.

Next, when the switching valve 31 is switched to the switching position (d),
Since the pressure oil from the external hydraulic pressure source 32 is introduced as pilot pressure into the spool end chamber C through the pilot pipe 33, the communication port 27, the circumferential groove 25, and the communication port 26, the spool 19
The hydraulic pressure from the external hydraulic power source 32 acts on the end surface on one end side of the
The spool 19 overcomes the spring force of the spring 20 and slides in the Y direction shown by the arrow to maintain this state. Then, the switching port 23 puts the spool annular chamber D and the large oil chamber A into communication with each other, and introduces the drive pressure of the hydraulic motor 1 into the large oil chamber A. As a result, the control piston 16 extends in the Y direction indicated by the arrow based on the pressure receiving area difference between the large oil chamber A and the small oil chamber B, and sets the displacement variable portion 1A of the hydraulic motor 1 to a large displacement.

Thus, as indicated by the solid line in FIG. 2, the capacity of the hydraulic motor 1 can be switched between a small capacity and a large capacity by the switching operation of the switching valve 31 and fixed, and the hydraulic motor 1 can be appropriately fast-small. Can be rotated with torque or low speed-high torque.

Therefore, in this embodiment, since the capacity can be fixed to a large capacity or a small capacity only with the switching valve of the switching valve 31, it can be used as a second speed motor or as a fixed motor depending on the usage conditions of the hydraulic motor 1. Multi-functionalization can be achieved.
Further, a single displacement control device 10 may be attached to the hydraulic motor 1 as shown in FIG. 3, the control valve 6 as in the prior art is not required, and the entire hydraulic motor 1 can be made compact and compact. When used as a traveling motor, the entire casing of the hydraulic motor 1 can be housed within the shoe width of the crawler belt, and so-called "in-shoe" can be achieved.

The hydraulic motor 1 shown in FIG. 3 is an oblique shaft type hydraulic motor, and the capacity variable portion 1A is provided in the casing of the hydraulic motor 1.
Cylinder block 1B and output shaft together with the valve plate that composes
1C etc. are provided.

Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

However, the feature of this embodiment is that three lands 41A, 41B, 41 are provided on the spool 41 slidably provided in the spool cylinder 17.
C are formed so as to be spaced apart in the axial direction, a spool end chamber C is provided between the land 41A and the plug 18, a spool annular chamber D is provided between the lands 41B and 41C, and a spool annular chamber D is provided between the land 41C and the bottom 17B. A spring chamber E is defined between the lands 41A and 41B, and another spool annular chamber F is defined between the lands 41A and 41B. The spool annular chamber F is springed in the spool 41 via an oil passage 42 formed in, for example, an L shape. Room E
There is always a structure to communicate with.

Here, in the spring chamber E, a compression spring 43 is disposed between the bottom portion 17B and the land 41C, and the spring 43 constantly biases the spool 41 in the X direction shown by the arrow. Further, a communication port 44 for constantly communicating the spool annular chamber D, the small oil chamber B, and the pressure introducing port 21 is radially provided at the base end of the rod portion 16B of the control piston 16, and the switching port 23 is Spool 41 shows arrow X, Y
By sliding in the direction, it communicates with either of the spool annular chambers D and F via the land 41B.

Then, when the switching valve 31 is set to the switching position (C), the switching port 23 continues to communicate with the spool annular chamber D as shown in the figure, so that the drive pressure of the hydraulic motor 1 is changed to the pressure introducing pipe 5, the pressure introducing port 21, and the communicating port. It is introduced into the large oil chamber A via 44 and the like, and the control piston 16 is extended in the Y direction shown by the arrow to set the displacement variable portion 1A of the hydraulic motor 1 to a large displacement. Also, switching valve
When 31 is switched to the switching position (d), the hydraulic pressure from the hydraulic pressure source 32 is introduced as pilot pressure into the spool end chamber C,
Since the spool 41 slides in the Y direction shown by the arrow against the compression spring 43, the switching port 23 comes to communicate with the spool annular chamber F, and the large oil chamber A has the communication passage 24, the switching port 23, and the spool annular chamber. The tank pressure is established by communicating with the spring chamber E through the chamber F and the oil passage 42. As a result, the control piston 16 moves in the direction indicated by the arrow X by the driving pressure of the hydraulic motor 1 acting in the small oil chamber B.
Direction, and the capacity variable portion 1A of the hydraulic motor 1 is set to a small capacity.

Thus, in this embodiment having such a configuration, the capacity of the hydraulic motor 1 can be switched between a small capacity and a large capacity and fixed, as indicated by the characteristic line shown by the dotted line in FIG. Has almost the same effect as.

In each of the above-described embodiments, the spring chamber E is connected to the casing body 12 via the communication port 29, the circumferential groove 28, and the communication port 30, respectively.
Although it is described that the connecting port 34 is bored in the axial direction of the control piston 16 as illustrated by the phantom line in FIG. 1, it is directly connected to the other end side protruding portion of the rod portion 16B. It may be opened.

[Effect of device]

The hydraulic motor displacement control device according to the present invention is as described above in detail, and has the effects of the following items.

Since the capacity can be fixed to a large capacity or a small capacity only by switching the switching valve, it can be used as a second speed motor or a fixed motor depending on the usage conditions of the hydraulic motor.
Multi-functionalization can be achieved.

A single displacement control device may be attached to the hydraulic motor, which eliminates the need for a control valve as in the prior art and allows a compact and compact structure. Therefore, when used as a traveling motor, the entire casing of the hydraulic motor can be accommodated within the shoe width of the crawler belt.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view showing a motor displacement control device according to this embodiment, and FIG. 2 shows a relationship between pilot pressure and motor displacement. The diagram shown in FIG. 3, FIG. 3 is a longitudinal sectional view of a hydraulic motor incorporating a displacement control device, and FIG. 4 is a longitudinal sectional view similar to FIG. 1 showing a second embodiment, FIG. 5 and FIG. Shows a prior art, FIG. 5 is a circuit configuration diagram showing a displacement control device for a hydraulic motor, and FIG. 6 is a diagram showing a relationship between drive pressure and motor displacement. 1 ... hydraulic motor, 1A ... variable volume part, 2A, 2B ... hydraulic piping, 3 ... high pressure selection valve, 11 ... casing, 12 ... casing body, 13 ... lid, 14 ... cylinder, 16 …… Control piston, 17 …… Spool cylinder, 19,41 …… Spool, 20,43 …… Compression spring, 21 …… Pressure introducing port, 2
2,26,29,44 …… Communication port, 23 …… Switching port, 27 ……
Communication passage, 25,28, ... Circumferential groove, 27,30,34 …… Contact port, 31
...... Switching valve, 32 ...... External hydraulic power source, A ...... Large oil chamber, B ......
Small oil chamber, C ... Spool end chamber, D ... Spool annular chamber, E ... Spring chamber.

Claims (1)

[Scope of utility model registration request] 1. A casing whose inside is a cylinder, and one end side of which is slidably provided in the cylinder of the casing,
While defining the inside of the casing into a large oil chamber and a small oil chamber,
A control piston, the other end of which protrudes out of the casing and is connected to the variable capacity portion of the hydraulic motor, a spool slidably provided in a spool cylinder formed in the control piston, and the spool for the spool. A spool annular chamber that is defined in the cylinder, is formed in the axial middle of the spool, and is in constant communication with the small oil chamber, a spool end chamber formed at one end side and a spring chamber formed at the other end side, A spring provided in a spring chamber for constantly urging the spool toward the spool end chamber side, a pressure introducing port for introducing the driving pressure of the hydraulic motor into the small oil chamber, and the control piston, A switching port for selectively communicating the large oil chamber with either the spring chamber or the spool annular chamber by sliding the spool, and the spool end chamber with the casing or One communication port for communicating with the outside of the control piston, a switching valve for switching and connecting the one communication port to a hydraulic source and a drain, and another communication port for communicating the spring chamber with the casing or the outside of the control piston, A displacement control device for a hydraulic motor, which includes a drain that is always connected to another communication port.