JPH087121Y2 - Hydraulic circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic circuit used in a hydraulic cylinder device or the like used in a truck.

[Prior Art] FIG. 3 is a system diagram showing a conventional hydraulic circuit for operating a hydraulic actuator.

One line in the hydraulic pump 1 is the first hydraulic line 1a
And the other pipeline of the hydraulic pump 1 communicates with the second hydraulic pipeline 1b, and the hydraulic pipeline 1a communicates with the hydraulic actuator 2
Of the hydraulic actuator 2 and the hydraulic line 1b communicates with the displacement chamber 2b of the hydraulic actuator 2.

The hydraulic line 1a includes a line 1c to the hydraulic pressure switching valve 13, a pilot line 13a to the hydraulic pressure switching valve 13, and a check valve 5a.
The hydraulic line 1b is connected to the relief valve 5 via a line 1d to the hydraulic switching valve 13 and the pilot line 13 to the hydraulic switching valve 13.
b, the check valve 5b, and the relief valve 5. The relief valve 5 is connected to the reservoir 4.
A conduit 13c is connected between the reservoir 4 and the reservoir 4.

 The operation in FIG. 3 is as follows.

When the hydraulic pump 1 is rotated in one rotation direction, the hydraulic pipeline 1a side becomes the high pressure discharge side, and the pressure oil discharged to the hydraulic pipeline 1a is transferred to the displacement chamber 2a of the hydraulic actuator 2.
Is pressed to push the piston 2c to the right and the hydraulic line
The high pressure generated in 1a sets the hydraulic pressure switching valve 13 to the position of 13B via the pilot conduit 13a.

At this time, the rotation of the hydraulic pump 1 to one side causes the hydraulic line 1b and the displacement chamber 2b to become a low pressure side, and the piston 2c moves to the right due to the high pressure in the displacement chamber 2a.

As a result, the hydraulic oil displaced from the displacement chamber 2b by the transition is used as the intake oil to the hydraulic pump 1, and the shortage in the intake is the reservoir 4 and the pipeline 13.
c, the switching position 13B of the switched hydraulic switching valve 13, the pipeline 1d
And is sucked into the hydraulic pump 1 via the hydraulic line 1b.

In this case, since the hydraulic switching valve 13 is set to the switching position 13B, the communication from the hydraulic pipeline 1a to the reservoir 4 via the pipeline 1c is closed at the switching position 13B. Therefore, when an excessive load is applied to the piston 2c, an excessive hydraulic pressure is about to be generated in the hydraulic pressure pipe 1a.

However, the hydraulic pressure that tends to become excessive in the hydraulic pressure line 1a acts on the relief valve 5 via the check valve 5a,
Due to the action, a part of the pressure oil on the hydraulic pipeline 1a side is relieved from the relief valve 5 to the reservoir 4 to protect the hydraulic circuit.

Conversely, when the hydraulic pump 1 is rotated in the other rotation direction, the pressure oil from the hydraulic pump 1 is discharged to the hydraulic pipeline 1b side, and the hydraulic pipeline 1b becomes the high pressure side. The pressure oil discharged to the hydraulic line 1b by the discharge is pressure-fed to the displacement chamber 2b in the hydraulic actuator 2 to press the piston 2c leftward,
In addition, the high pressure generated in the hydraulic line 1b sets the hydraulic pressure switching valve 13 to the position 13C via the pilot line 13b.

At this time, the hydraulic pump 1 rotates to the other side, so that the hydraulic pipe 1a becomes the suction side of the hydraulic pump 1.
As a result, the hydraulic line 1a and the displacement chamber 2a are on the low pressure side, and the piston 2c moves to the left due to the high pressure in the displacement chamber 2b.

The hydraulic oil displaced from the displacement chamber 2a by this transition is used as the intake oil to the hydraulic pump 1, and the excess or deficiency in the intake is determined by the hydraulic lines 1a, 1c, and the switched hydraulic switching valve 13. It is discharged to the reservoir 4 via the switching position 13C and the conduit 13c, or vice versa.
Is sucked into the hydraulic line 1a via the switching position 13C.

In this case, since the hydraulic pressure switching valve 13 is set to the switching position 13C, the communication from the hydraulic pipeline 1b to the reservoir 4 via the pipeline 1d is closed at the switching position 13C. Therefore, when an excessive load is generated on the piston 2c, an excessive hydraulic pressure is about to be generated on the hydraulic pipe line 1b.

However, the hydraulic pressure that tends to become excessive in the hydraulic line 1b acts on the relief valve 5 via the check valve 5b,
By this action, a part of the pressure oil on the hydraulic pipe 1b side is relieved from the relief valve 5 to the reservoir 4 and protects the hydraulic circuit as described above.

In the above operation, the check valves 5a and 5b are arranged such that, when one of the hydraulic lines 1a or 1b is about to increase to an excessive hydraulic pressure, the excessive pressure oil causes the excess pressure oil The check valve 5a or 5b is used to cause the relief valve 5 to perform a relief operation.

The reason why there are two check valves 5a and 5b is as follows.

The hydraulic pressure of the excessive hydraulic line (1a or 1b) acts on the relief valve 5 via one check valve (5a or 5b), and the hydraulic pressure acting on the relief valve 5 acts on the other hydraulic line ( The other check valve (5b or 5a) is provided so as not to communicate with the 1b or 1a) side.

[Problems to be solved by the invention] However, the fact that two check valves 5a and 5b are provided as described above not only requires two check valves, but also connects the two check valves by piping. The pipeline to operate becomes complicated.

In particular, when the hydraulic actuator 2 shown in FIG. 3 is used for a hydraulic cylinder device in an automobile (such as a truck), it is necessary to pipe these hydraulic circuits in a limited space of the automobile. It is desirable to be as simple as possible.

An object of the present invention is to provide a hydraulic circuit that alleviates the above problems.

[Characteristics for Solving the Problems] The first hydraulic line and the second hydraulic line are set such that the hydraulic line on one side thereof is set as the discharge line of the hydraulic pump depending on the rotation direction of the hydraulic pump. The hydraulic line on the other side is set as the suction line of the hydraulic pump.

Therefore, when the hydraulic pump rotates to one side, the first hydraulic line side becomes the discharge line (high hydraulic line) of the hydraulic pump, and the second hydraulic line becomes the suction line (low hydraulic line) of the hydraulic pump. Hydraulic line). Conversely, when the hydraulic pump rotates to the other side, the first hydraulic line side becomes the suction line,
The second hydraulic pipeline side becomes the discharge pipeline side.

In addition, the first hydraulic line and the second hydraulic line,
A hydraulic switching valve is provided between the relief valve and the reservoir.

 These configurations are those conventionally used.

In such a conventional configuration, the present invention is
Of the hydraulic line or the second hydraulic line, the hydraulic pressure switching valve causes the high-pressure side hydraulic line to become a relief valve and the low-pressure side hydraulic line It is characterized in that the side that has become a passage communicates with the reservoir.

That is, the rotation of the hydraulic pump in one direction causes the first hydraulic pipeline side to move toward the hydraulic pump discharge pipeline side and the second hydraulic pipeline side.
When the hydraulic line side of the above becomes the suction line side, the hydraulic pressure switching valve is switched by the hydraulic pressure difference between the first hydraulic line and the second hydraulic line, and the first hydraulic line becomes The relief valve and the second hydraulic line communicate with the reservoir. Conversely, when the hydraulic pump rotates in the other direction, the hydraulic pressure switching valve is switched to the other due to the hydraulic pressure difference between the two, and the second hydraulic line serves as the relief valve and the first hydraulic pressure. The conduit will communicate with the reservoir.

[Embodiment] The present invention will be described below based on an embodiment.

FIG. 1 is a system diagram showing a hydraulic circuit as an embodiment of the present invention.

In FIG. 1, one pipeline in the hydraulic pump 1 communicates with the first hydraulic pipeline 1a, the other pipeline in the hydraulic pump 1 communicates with the second hydraulic pipeline 1b, and the hydraulic pipeline 1a The hydraulic actuator 2 communicates with the displacement chamber 2a, and the hydraulic line 1b communicates with the displacement chamber 2b of the hydraulic actuator 2.

Further, the hydraulic line 1a communicates with the line 1c to the hydraulic switching valve 3 and the pilot line 3a, and the hydraulic line 1b communicates with the line 1d to the hydraulic switching valve 3 and the pilot line 3b. A conduit 3c from the hydraulic pressure switching valve 3 communicates with the reservoir 4.

The configuration up to this point is basically the same as the conventional configuration shown in FIG.

In contrast to the conventional hydraulic switching valve 13 having the 3-port / 3-position configuration, the hydraulic switching valve 3 has the 4-port / 3-position configuration, and the conduit 3d from the hydraulic switching valve 3 is provided with the relief valve 5. Is in communication with.

FIG. 2 is a side sectional view showing a specific structure of the hydraulic pressure switching valve 3 shown in FIG.

In FIG. 2, a cylinder 3e is fitted with a spool valve A capable of sliding in the axial direction, and the spool valve A has lands A1, A2, A3 and A4 and groove portions A0, A5 on its outer diameter. A6, A7 and A8 are cut, the groove A5 and the groove A6 communicate with each other through a hole A9 formed in the spool valve A, and the groove A7 and the groove A8 communicate with each other through a hole A10 formed in the spool valve A. are doing.

Port 3r communicates with conduit 3c, both ports 3h and 3i communicate with conduit 3d, and conduits 1c, 1d, 3c and 3d are conduits with the same reference numerals in FIG.

Plates 3k and 3p are provided at both ends of the spool valve A. The plate 3k is acted on by the spring 3m to the right and the plate 3p is acted on by the spring 3q to the left.

The operation of the configuration shown in FIG. 1 is as follows.

When the hydraulic pump 1 is not driven, the hydraulic pressures of the hydraulic lines 1a and 1b are the same, that is, atmospheric pressure. As a result, the pilot lines 3a and 3b are both brought to the atmospheric pressure, and the hydraulic pressure switching valve 3 sets the switching position to the neutral position of 3A by the spring biasing force provided inside.

When the hydraulic pump 1 is driven and the rotation thereof is rotated in one rotation direction, the hydraulic pipeline 1a side becomes the high-pressure discharge side, and the pressure oil discharged to the hydraulic pipeline 1a by the discharge is the displacement chamber in the hydraulic actuator 2. The high pressure generated in the hydraulic conduit 1a by pushing the piston 2c to the right by being pumped to the 2a sets the hydraulic pressure switching valve 3 to the position 3B via the pilot conduit 3a.

At this time, the rotation of the hydraulic pump 1 to one side causes the hydraulic line 1b and the displacement chamber 2b to become a low pressure side, and the piston 2c moves to the right due to the high pressure in the displacement chamber 2a.

As a result, the hydraulic oil displaced from the displacement chamber 2b due to the transition is used as the intake oil to the hydraulic pump 1, and the shortage in the intake is due to the reservoir 4, the conduit 3c,
It is sucked into the hydraulic pump 1 via the switching position 3B of the switched hydraulic switching valve 3, the conduit 1d and the hydraulic conduit 1b.

Further, in this case, when an excessive load is applied to the piston 2c, the hydraulic lines 1a, 1c and the displacement chamber 2a tend to cause an excessive increase in hydraulic pressure. But in this case
The oil pressure which is about to become excessive in the hydraulic line 1a acts on the relief valve 5 via the line 1c, the switching position 3B and the line 3d, whereby the relief valve 5 becomes excessive in the hydraulic line 1a. Relieve pressure oil to the reservoir 4,
Protect the hydraulic circuit.

Conversely, when the hydraulic pump 1 is rotated in the other rotation direction, the pressure oil from the hydraulic pump 1 is discharged to the hydraulic pipeline 1b side, and the hydraulic pipeline 1b becomes the high pressure side. The pressure oil discharged to the hydraulic line 1b is used as the displacement chamber 2b in the hydraulic actuator 2.
The high pressure generated in the hydraulic line 1b by pushing the piston 2c to the left is set via the pilot line 3b to the hydraulic switching valve 3 at the switching position 3C.

At this time, the hydraulic pump 1 rotates to the other side, so that the hydraulic pipe 1a becomes the suction side of the hydraulic pump 1.
As a result, the hydraulic line 1a and the displacement chamber 2a are on the low pressure side, and the piston 2c moves to the left due to the high pressure in the displacement chamber 2b.

The hydraulic oil displaced from the displacement chamber 2a by this transition is used as the intake oil to the hydraulic pump 1, and the excess or deficiency in the intake is determined by the hydraulic pipeline 1a, the pipeline 1c, and the switched hydraulic switching valve 3. It is discharged to the reservoir 4 via the switching position 3C and the conduit 3c, or vice versa, is sucked into the hydraulic pump 1 from the reservoir 4 via the switching position 3C and the hydraulic conduit 1a.

In this case, when an excessive load is applied to the piston 2c, the hydraulic line 1b, the line 1d and the displacement chamber 2b tend to cause an excessive increase in hydraulic pressure. However, also in this case, the hydraulic pressure that is about to become excessive in the hydraulic line 1b is
It acts on the relief valve 5 via the switching position 3C and the conduit 3d, whereby the relief valve 5 relieves excessive pressure oil in the hydraulic conduit 1b to the reservoir 4 and protects the hydraulic circuit in the same manner as described above. .

The description of the operation of the hydraulic pressure switching valve 3 in FIG. 1 has been made with reference to the hydraulic pressure switching valve 3 illustrated by the symbols, but the operation of the hydraulic pressure switching valve 3 having the specific configuration is as follows.

When the hydraulic pump 1 is not driven, both the pipelines 1c and 1d are at atmospheric pressure as described above.

In FIG. 2, when the pipelines 1c and 1d have such atmospheric pressure, on the port 3f side, the groove portion A6, the perforations A9 and A5, which are in communication with the port 3f, are also atmospheric pressure, On the port 3g side, the groove portion A7, the perforation A10, and the groove portion A8 which are in communication with the port 3g are also at atmospheric pressure.

That is, the spool valve A has atmospheric pressure at both ends, and the oil pressure in the axial direction is balanced. Also,
In this state, the spring 3m biases the spool valve A to the right via the plate 3k, the spring 3q biases the spool valve A to the left via the plate 3p, and the plates 3k and 3p , The spool valve A is set to the neutral position by the plates 3k and 3p as shown in the drawing, and the pipe 1c is connected to both the pipe 3c and the pipe 3d. The communication is closed, the pipeline 1d is also closed the communication with both the pipeline 3c and the pipeline 3d, and the hydraulic pressure switching valve 3 is set to the switching position 3A in the hydraulic pressure switching valve 3 shown by a symbol in FIG. become.

The perforation A9 also serves as the pilot conduit 3a in FIG. 1, and the perforation A10 also serves as the pilot conduit 3b in FIG.

The hydraulic line 1a, that is, the line 1c becomes high pressure, and the hydraulic line 1b
That is, when the pipe line 1d becomes low in pressure, the high pressure in the pipe line 1c is transmitted to the groove A5 through the port 3f, the groove portion A6 and the perforation A9, and the high pressure acts on the left end of the spool valve A to move the spool valve A to the right. Press in one direction.

On the other hand, the low pressure in the conduit 1d is transmitted to the groove A8 via the port 3g, the groove A7 and the perforation A10, so that the right end of the spool valve A has a low pressure.

As a result, due to the pressure difference between both ends of the spool valve A, the spool valve A moves to the right end while compressing the spring 3q. At this time, the plate 3k remains in contact with the shoulder 3j and does not move to the right from the illustrated position.

In this way, when the spool valve A moves to the right end, the high pressure side conduit 1c has the groove A6, the hole A9, the groove A5 and the port 3h.
And the land A2 is located between the port 3f and the port 3r to close the communication between the pipeline 1c and the pipeline 3c. Further, the low pressure side conduit 1d is connected to the conduit 3c via the port 3r.
And the land A3 is located between the port 3g and the port 3i to close the communication between the pipeline 1d and the pipeline 3d.

This state is, after all, the hydraulic switching valve 3 shown by a symbol in FIG.
In, the hydraulic pressure switching valve 3 is set to the switching position 3B.

On the contrary, the hydraulic line 1b, that is, the line 1d becomes high pressure,
When the hydraulic pipeline 1a, that is, the pipeline 1c becomes low in pressure, the high pressure in the pipeline 1d is transmitted to the groove A8 through the port 3g, the groove A7 and the perforation A10, and the high pressure acts on the right end of the spool valve A. Press valve A to the left.

On the other hand, the low pressure at the port 3f is transmitted to the groove A5 through the groove A6 and the perforation A9, so that the left end of the spool valve A has a low pressure.

As a result, due to the pressure difference between both ends of the spool valve A, the spool valve A moves to the left end while compressing the spring 3m via the plate 3k. At this time, the plate 3p remains in contact with the shoulder 3n and does not move to the left from the illustrated position.

In this way, when the spool valve A moves to the left end, the high pressure side conduit 1d has the groove A7, the hole A10, the groove A8 and the port 3
The land A3 communicates with the pipeline 3d via i, and the land A3 is located between the port 3r and the port 3g to close the communication between the pipeline 1d and the pipeline 3c. Further, the low pressure side conduit 1c communicates with the conduit 3c via the ports 3f and 3r, the land A2 is located between the port 3f and the port 3h, and the conduit 1c and the conduit 3d are connected to each other. Close communication.

This state is, after all, the hydraulic switching valve 3 shown by a symbol in FIG.
In, the hydraulic pressure switching valve 3 is set to the switching position 3C.

[Effects of the Invention] As is apparent from the above description, the effects of the present invention are as follows.

The hydraulic pressure switching valve 3 causes the high-pressure side hydraulic line to act as the relief valve and the low-pressure side hydraulic pressure of the high-pressure side hydraulic line by the hydraulic pressure on the high-pressure side of the first hydraulic line or the second hydraulic line. With the configuration in which the side that has become a pipeline communicates with the reservoir, if only a single pipeline 3d is provided between the hydraulic pressure switching valve 3 and the relief valve 5, the same third as in the conventional case can be obtained. The hydraulic circuit shown can be operated.

This means that conventionally, both the pipe line connecting both ends of the check valve 5a and the pipe line connecting both ends of the check valve 5b are arranged, and from the connection point of the check valve 5a and the check valve 5b. Compared with the need for piping to connect to the relief valve 5, not only is the check valve unnecessary, but the piping has the advantage of being simple.

Further, when such a hydraulic circuit is used in an automobile, there is an advantage that the space can be effectively used because the piping to the limited space can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram showing a hydraulic circuit as an embodiment of the present invention, and FIG. 2 is a side sectional view showing the hydraulic switching valve 3 shown in FIG. 1 as a concrete structure. FIG. 3 is a system diagram showing a conventional hydraulic circuit. The main symbols used in the examples are as follows. 1: hydraulic pump, 1a and 1b: hydraulic line, 2: hydraulic actuator, 2a and 2b: displacement chamber, 3: hydraulic switching valve, 3c and 3d: line, 4: reservoir, 5: relief valve.

Claims (1)

[Scope of utility model registration request] 1. The first hydraulic line and the second hydraulic line are set such that the hydraulic line on one side thereof is set as the discharge line of the hydraulic pump depending on the rotation direction of the hydraulic pump, and the other side. The hydraulic line on the side of is set as the suction line of the hydraulic pump, and a hydraulic switching valve is provided between the first hydraulic line and the second hydraulic line, and the relief valve and the reservoir. In the above configuration, the hydraulic pressure switching valve causes the high-pressure side hydraulic pipeline to be connected to the relief valve by the hydraulic pressure on the high-pressure side of the first hydraulic pipeline or the second hydraulic pipeline. A hydraulic circuit characterized in that a side of the low-pressure side hydraulic line is communicated with the reservoir.