JP6161416B2 - Hydraulic control device - Google Patents

Description

  The present invention relates to a hydraulic control device for an industrial vehicle, and more particularly to controlling a single acting cylinder such as a lift cylinder of a forklift.

  The conventional hydraulic control apparatus shown in FIG. 2 forms an actuator port 2 in the valve body 1, and this actuator port 2 is connected to a lift cylinder C via a connection pipe 3 and a pipe 4 connected to the connection pipe 3. Is connected to the bottom chamber C1. A pressure sensor 5 is connected to the pipe 4.

A spool hole 6 is formed in the valve body 1, and a spool S is slidably incorporated in the spool hole 6. The spool S is formed with first to fourth annular grooves 7 to 10 from the left to the right in the drawing.
A high-pressure passage 11 connected to a pump (not shown) is formed around the spool hole 6, and neutral passages 12 are formed on both sides of the high-pressure passage 11. The neutral passage 12 communicates with a tank (not shown).

When the spool S is in the illustrated neutral position, the high-pressure passage 11 and the neutral passage 12 communicate with each other through the second and third annular grooves 8 and 9.
When the spool S is switched to the right, the second annular groove 8 is almost directly opposed to the high pressure passage 11, and the communication between the high pressure passage 11 and the neutral passage 12 is blocked. When the communication between the high pressure passage 11 and the neutral passage 12 is blocked, the high pressure fluid guided to the high pressure passage 11 is guided to the relay passage 13.

  Since the spool S is switched to the right as described above, the relay passage 13 communicates with the connection passage 14 via the first annular groove 7. An assembly hole 16 for incorporating the operation check valve 15 between the connection passage 14 and the actuator port 2 is formed in the valve body 1, and the operation check valve 15 is assembled in the assembly hole 16, The built-in hole 16 is blocked with a plug 17.

  The operation check valve 15 incorporated in the assembly hole 16 as described above forms a back pressure chamber 15b between the poppet 15a and the plug 17, and a spring 18 is interposed in the back pressure chamber 15b. The poppet 15 a closes the seat provided in the connection passage 14 by the spring force of the spring 18.

  Further, the back pressure chamber 15 b is formed with an orifice 19 that communicates with the actuator port 2, and communicates with the pilot passage 20. The pilot passage 20 communicates with the return passage 22 via a solenoid valve 21. The solenoid valve 21 is closed when the solenoid valve 21 is kept in a non-excited state and is opened when the solenoid valve 21 is kept in an excited state. ing.

  On the other hand, when the spool S is switched from the illustrated neutral position to the left, the connection passage 14 communicates with the tank passage 24 via the first annular groove 7 and the communication passage 23 formed in the spool S, and the return passage 22 The tank passage 24 communicates with the spool S through a communication passage 25 formed in the spool S.

Next, a case where the lift load W provided in the lift cylinder C is increased will be described.
When the load W is increased, the solenoid valve 21 is kept in a non-excited state to cut off the communication between the pilot passage 20 and the return passage 22 and the spool S is switched to the right in the drawing.

  When the spool S is switched as described above, the high-pressure fluid guided to the high-pressure passage 11 is guided to the connection passage 14 via the relay passage 13 and the first annular groove 7. The pressure fluid guided to the connection passage 14 in this way pushes open the poppet 15a of the operation check valve 15 and flows out to the actuator port 2, and from the actuator port 2 through the connection pipe 3 and the pipe 4, the lift cylinder C To the bottom chamber C1. When the pressure fluid is supplied to the bottom chamber C1, the lift cylinder C extends to increase the load W.

At this time, the load pressure in the bottom chamber C1 is detected by the pressure sensor 5, the purpose of which is as follows. That is, when the load W lifted by the forklift is excessive, if it is lifted high, the balance of the forklift is lost and becomes unstable, and sometimes there is a danger. Therefore, the load pressure is always detected by the pressure sensor 5 as described above, and the lift cylinder C can be controlled safely when the load pressure is excessive.

  When stopping the lift cylinder C in the process of raising it, the spool S switched to the right is returned to the neutral position. When the spool S returns to the neutral position, the high-pressure passage 11 communicates with the neutral passage 12, and the communication between the relay passage 13 and the connection passage 14 is also blocked. Therefore, no pressure fluid is supplied to the bottom chamber C1 of the lift cylinder C, and the lift cylinder C stops at the position.

  At this time, since the load pressure of the lift cylinder C is guided from the orifice 19 to the back pressure chamber 15b, the poppet 15a closes the seat portion by the action of the spring force of the spring 18 and the pressure of the back pressure chamber 15b. Therefore, the load W is held at the stop position of the lift cylinder C.

When the load W is lowered from the above state, first, the solenoid of the solenoid valve 21 is excited to open the solenoid valve 21, and the pilot passage 20 and the return passage 22 are communicated.
After the above, the spool S is switched to the left. When the spool S is switched to the left, the connection passage 14 communicates with the tank passage 24 via the first annular groove 7 and the communication passage 23. The return passage 22 communicates with the communication passage 25 and also communicates with the tank passage 24 via the communication passage 25 and the fourth annular groove 10.

In the above state, the load pressure of the lift cylinder C acts on the inclined surface 15c of the poppet 15a. At this time, the back pressure chamber 15b communicates with the tank passage 24 via the pilot passage 20, the solenoid valve 21, the return passage 24, and the communication passage 25. Therefore, the acting force on the inclined surface 15c causes the poppet 15a to The spring force of the spring 18 of the pressure chamber 15b is overcome, the poppet 15a is moved against the spring force of the spring 18, and the seat portion is opened.
If the seat portion is opened, the fluid in the bottom chamber C1 is guided to the tank passage 24 via the pipe 4, the connection pipe 3, the actuator port 2, the connection passage 14, the first annular groove 7, and the communication passage 23. The lift cylinder C is lowered.

  In the figure, reference numeral 26 is a centering spring provided at the end of the spool S, 27 is a manually operated shut-off valve, and the shut-off valve 27 is unable to lower the lift cylinder C due to a malfunction of the solenoid valve 21. In order to guide the pressure in the back pressure chamber 15b to the tank passage 24 by manual operation.

JP 2001-187902 A

In the conventional hydraulic control apparatus as described above, since the pressure sensor 5 is provided separately from the valve body 1, they have to be handled separately. Therefore, for example, when the valve body 1 is assembled and then assembled to an actual machine or the like, the pressure sensor 5 is also assembled at that time, and there has been a problem that the number of work steps during assembly is increased.
An object of the present invention is to provide a hydraulic control device capable of integrating a pressure sensor and a valve main body while using the valve main body in a conventional hydraulic control device as it is.

The first aspect of the invention includes a spool that is slidably incorporated in the valve body, and an operation check valve is provided in a communication process between a connection passage through which pressure fluid is guided in response to switching of the spool and an actuator port that communicates with the actuator. a hydraulic control device formed a back pressure chamber in the operate check valve, a plug for closing the upper xenon pressure chamber, attaching a pressure sensor to the plug, in that the arrangement for detecting the pressure of the back pressure chamber Has characteristics.
The second invention is characterized in that an orifice is provided in the communication process between the actuator port and the back pressure chamber.

According to the hydraulic control device of the first aspect of the invention, the pressure sensor can be assembled to the valve body, so that both of them can be handled integrally.
In addition , since a mounting hole is formed in the plug that closes the back pressure chamber, and the pressure sensor is mounted in this mounting hole, it is not necessary to add significant processing to the conventional hydraulic control device.
According to the hydraulic control device of the second invention, the existing orifice can be utilized as it is. That is, a single-acting cylinder or the like may have a peak pressure in the initial stage of expansion, but since the orifice is used, the pressure sensor is not affected by the peak pressure.

It is the figure which made the cross section the part of the valve body. It is sectional drawing which shows the conventional hydraulic control apparatus.

The embodiment shown in FIG. 1 is characterized in that the pressure sensor pr is provided in the plug 17, and the other features are the same as those of the conventional hydraulic control device. However, in the description of this embodiment, the same parts as those of the conventional hydraulic control apparatus will be described again.
The hydraulic control device in this embodiment forms an actuator port 2 in the valve body 1, and this actuator port 2 is connected to the bottom chamber of the lift cylinder C via a connection pipe 3 and a pipe 4 connected to the connection pipe 3. Connected to C1.

A spool hole 6 is formed in the valve body 1, and a spool S is slidably incorporated in the spool hole 6. The spool S is formed with first to fourth annular grooves 7 to 10 from the left to the right in the drawing.
A high-pressure passage 11 connected to a pump (not shown) is formed around the spool hole 6, and neutral passages 12 are formed on both sides of the high-pressure passage 11. The neutral passage 12 communicates with a tank (not shown).

When the spool S is in the illustrated neutral position, the high-pressure passage 11 and the neutral passage 12 communicate with each other through the second and third annular grooves 8 and 9.
When the spool S is switched to the right, the second annular groove 8 is almost directly opposed to the high pressure passage 11, and the communication between the high pressure passage 11 and the neutral passage 12 is blocked. When the communication between the high pressure passage 11 and the neutral passage 12 is blocked, the high pressure fluid guided to the high pressure passage 11 is guided to the relay passage 13.

  Since the spool S is switched to the right as described above, the relay passage 13 communicates with the connection passage 14 via the first annular groove 7. An assembly hole 16 for incorporating the operation check valve 15 between the connection passage 14 and the actuator port 2 is formed in the valve body 1, and the operation check valve 15 is assembled in the assembly hole 16, The built-in hole 16 is blocked with a plug 17.

The operation check valve 15 incorporated in the assembly hole 16 as described above forms a back pressure chamber 15b between the poppet 15a and the plug 17, and a spring 18 is interposed in the back pressure chamber 15b. The poppet 15 a closes the seat provided in the connection passage 14 by the spring force of the spring 18.
The plug 17 is provided with a mounting hole 28, and a pressure sensor pr is attached to the mounting hole 28. A seal member 29 is provided at a portion of the pressure sensor pr to be inserted into the mounting hole 28. By attaching pr to the attachment hole 28, the attachment hole 28 can be sealed with the seal member 29.

Further, the back pressure chamber 15 b is formed with an orifice 19 that communicates with the actuator port 2, and communicates with the pilot passage 20. The pilot passage 20 communicates with the return passage 22 via a solenoid valve 21. The solenoid valve 21 is closed when the solenoid valve 21 is kept in a non-excited state and is opened when the solenoid valve 21 is kept in an excited state. ing.
On the other hand, when the spool S is switched from the illustrated neutral position to the left, the connection passage 14 communicates with the tank passage 24 via the first annular groove 7 and the communication passage 23 formed in the spool S, and the return passage 22 The tank passage 24 communicates with the spool S through a communication passage 25 formed in the spool S.

Next, a description will be given of a case of raising the load W of the lift provided in the lift cylinder C.
When the load W is increased, the solenoid valve 21 is kept in a non-excited state to cut off the communication between the pilot passage 20 and the return passage 22 and the spool S is switched to the right in the drawing.
When the spool S is switched as described above, the high-pressure fluid guided to the high-pressure passage 11 is guided to the connection passage 14 via the relay passage 13 and the first annular groove 7. The pressure fluid guided to the connection passage 14 in this way pushes open the poppet 15a of the operation check valve 15 and flows out to the actuator port 2, and from the actuator port 2 through the connection pipe 3 and the piping 4, the lift cylinder C To the bottom chamber C1. When the pressure fluid is supplied to the bottom chamber C1, the lift cylinder C extends to increase the load W.

At this time, the load pressure of the lift cylinder C is guided to the back pressure chamber 15b through the orifice 19, and the pressure in the back pressure chamber 15b is detected by the pressure sensor pr. Note that the detection of the load pressure applied by the back pressure chamber 15b is the same as in the case of the conventional hydraulic control device.
However, since the back pressure chamber 15b is provided with the orifice 19, for example, even if a peak pressure is generated in the lift cylinder C, the pressure propagation speed is somewhat relaxed by the orifice 19, so that the pressure sensor pr is the peak. Less likely to detect pressure.

  Further, when the lift cylinder C is raised and stopped, the spool S switched to the right is returned to the neutral position. When the spool S returns to the neutral position, the high-pressure passage 11 communicates with the neutral passage 12, and the communication between the relay passage 13 and the connection passage 14 is also blocked. Therefore, no pressure fluid is supplied to the bottom chamber C1 of the lift cylinder C, and the lift cylinder C stops at the position.

  At this time, since the load pressure of the lift cylinder C is guided from the orifice 19 to the back pressure chamber 15b, the poppet 15a closes the seat portion by the action of the spring force of the spring 18 and the pressure of the back pressure chamber 15b. Therefore, the load W is held at the stop position of the lift cylinder C.

When the load W is lowered from the above state, first, the solenoid of the solenoid valve 21 is excited to open the solenoid valve 21, and the pilot passage 20 and the return passage 22 are communicated.
After the above, the spool S is switched to the left. When the spool S is switched to the left, the connection passage 14 communicates with the tank passage 24 via the first annular groove 7 and the communication passage 23. The return passage 22 communicates with the communication passage 25 and also communicates with the tank passage 24 via the communication passage 25 and the fourth annular groove 10.

In the above state, the load pressure of the lift cylinder C acts on the inclined surface 15c of the poppet 15a. At this time, the back pressure chamber 15b communicates with the tank passage 24 via the pilot passage 20, the solenoid valve 21, the return passage 22, and the communication passage 25, so that the acting force on the inclined surface 15c is reduced by the back pressure chamber 15b. The spring force of the spring 18 is overcome, the poppet 15a is moved against the spring force of the spring 18, and the seat portion is opened.
If the seat portion is opened, the fluid in the bottom chamber C1 is guided to the tank passage 24 via the pipe 4, the connection pipe 3, the actuator port 2, the connection passage 14, the first annular groove 7, and the communication passage 23. The lift cylinder C is lowered.

  In the figure, reference numeral 26 is a centering spring provided at the end of the spool S, 27 is a manually operated shut-off valve, and the shut-off valve 27 is unable to lower the lift cylinder C due to a malfunction of the solenoid valve 21. In order to guide the pressure in the back pressure chamber 15b to the tank passage 24 by manual operation.

  Ideal for use in forklift lift cylinders.

DESCRIPTION OF SYMBOLS 1 Valve body 2 Actuator port C Lift cylinder which is a single acting cylinder pr Pressure sensor S Spool 14 Connection passage 15 Operate check valve 15a Poppet 15b Back pressure chamber 28 Mounting hole

Claims (2)

A spool is slidably incorporated in the valve body, and an operation check valve is provided in a communication process between a connection passage through which pressure fluid is guided according to the switching of the spool and an actuator port communicating with the actuator. A hydraulic control device having a pressure chamber,
A hydraulic control device configured to detect a pressure of the back pressure chamber by attaching a pressure sensor to the plug for closing the back pressure chamber and the plug . 2. The hydraulic control device according to claim 1, wherein an orifice is provided in a communication process between the actuator port and the back pressure chamber .

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