JP2008064298A - Actuator control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent vibration of a pilot spool PS.
When the pilot spool holds the normal position, the spring chamber 21 is closed, while when the main spool is held in the neutral position, the first introduction port 39, the pressure chamber, the spring chamber, and the tank passage are provided. 13. The communication between the second introduction port 40 and the return passage 4 is blocked, and when the main spool MS is moved from the neutral position in the direction of returning the working fluid, the spring chamber communicates with the tank passage, The first introduction port communicates with the pressure chamber, the second introduction port communicates with the return passage, and the pilot spool is provided with a control orifice in the communication process between the annular recess and the spring chamber. While the annular recess and the spring chamber are always in communication with each other through the orifice, the pilot spool is arranged before and after the control orifice. As pressure is maintained in the spring force equivalent of the spring chamber, and the arrangement for controlling the opening of the first introduction port.
[Selection] Figure 1

Description

  The present invention relates to an actuator control device suitable for controlling a lowering operation of a lift cylinder in, for example, a forklift.

  As an apparatus of this type, the present applicant has already applied for an invention related to Japanese Patent Application No. 2005-360741 with the JPO. The contents are as shown in FIGS. 2 and 3, and will be specifically described below. This conventional device is assumed to control a lift cylinder of a forklift. In the valve body B, an actuator port 1 connected to the lift cylinder and a spool hole 2 into which a main spool MS is slidably incorporated. Is forming. The valve body B incorporates an operation check valve V, and the actuator port 1 communicates with the supply passage 3 and the return passage 4 via the operation check valve V. In other words, the operation check valve V is provided at the junction of the supply passage 3 and the return passage 4.

  The operation check valve V is configured to open and close the seat portion 6 provided in the valve body B by a poppet portion 5 a provided in the valve body 5. When the seat portion 6 is opened, the actuator port 1 communicates with the supply passage 3 and the return passage 4. When the seat portion 6 is closed, the actuator port 1 communicates with the supply passage 3 and the return passage 4. It is configured to be blocked.

  Further, the operation check valve V is provided with a cylindrical portion 5b on the side opposite to the poppet portion 5a, and this cylindrical portion 5b faces the pressure chamber 7. An orifice 8 is formed in the cylindrical portion 5 b, and the pressure chamber 7 is always in communication with the actuator port 1 through the orifice 8. Further, a spring 9 is provided in the pressure chamber 7, and normally, the poppet portion 5 a closes the seat portion 6 by the action of the spring force of the spring 9.

  In the operation check valve V as described above, the diameter of the cylindrical portion 5 b is larger than the diameter of the seat portion 6. Therefore, if the pressure acting on the outer periphery of the poppet portion 5a is equal to the pressure acting on the cylinder portion 5b when the poppet portion 5a closes the seat portion 6, in other words, the actuator port 1 and the pressure chamber 7 If the pressures are equal, the seat portion 6 is closed by the poppet portion 5a, and the operation check valve V is kept closed.

  On the other hand, a supply-side annular groove 10 and a return-side annular groove 11 are formed in the main spool MS. The supply-side annular groove 10 is always in communication with a pump passage 12 communicated with a pump (not shown), and when the main spool MS is moved from the neutral position shown in the drawing to the right in the drawing, the supply-side annular groove 10 passes through the supply-side annular groove 10. Thus, the pump passage 12 and the supply passage 3 are communicated with each other. The return-side annular groove 11 allows the return passage 4 and the tank passage 13 to communicate with each other when the main spool MS moves from the neutral position shown in the drawing to the left.

  The main spool MS described above incorporates a pilot spool PS, and first to third ports 14 to 16 are formed in a positional relationship corresponding to the pilot spool PS. The first port 14 is closed when the main spool MS is at the neutral position shown in the figure, and when the main spool MS moves from the neutral position to the left in the drawing, that is, in the direction to return the fluid from the actuator, The pressure chamber 7 communicates with the pressure chamber 7.

  The second port 15 is closed when the main spool MS is in the neutral position shown in the drawing, and when the main spool MS moves in the left direction in the drawing as described above, the annular groove 18 formed in the inner surface of the spool hole 2. The tank passage 13 communicates with the tank. Further, the third port 16 is closed when the main spool MS is in the neutral position shown in the figure, and communicates with the return passage 4 when the main spool MS moves in the left direction of the drawing as described above.

  The first to third ports 14 to 16 configured as described above maintain the following positional relationship. That is, when the main spool MS is moved from the neutral position to the left in the drawing, first, the second port 15 communicates with the annular groove 18, and then the first port 14 enters the pressure chamber 7 via the flow path 17. At the same time, the third port 16 communicates with the return passage 4. After the third port 16 communicates with the return passage 4, as shown in FIGS. 2 and 3, the relative relationship that the return passage 4 and the tank passage 13 communicate with each other through the notch 19 formed in the main spool MS is established. I keep it.

  Further, the pilot spool PS incorporated in the main spool MS has one end facing the pilot chamber 20 and the other end facing the spring chamber 21. A spring 22 is provided in the spring chamber 21, and the pilot spool PS is normally pressed against the end surface of the pilot chamber 20 by the spring force of the spring 22. The spring chamber 21 is always in communication with the second port 15 via a communication passage 23 formed in the main spool MS. Therefore, when the second port 15 communicates with the annular groove 18, the spring chamber 21 also communicates with the tank passage 13 via the annular groove 18.

  The pilot spool PS as described above is formed with an annular recess 24, and this annular recess 24 is always in communication with the pilot chamber 20 via a control throttle 25 formed in the pilot spool PS.

  When the pilot spool PS is in the illustrated normal position due to the spring force of the spring 22, the second port 15 is closed by the first land portion 26 formed in the pilot spool PS.

  In the figure, reference numeral 28 denotes a centering spring which keeps the main spool MS at the neutral position shown in the figure. Reference numeral 29 denotes a load check valve provided in the supply passage 3 and allows only the flow from the pump passage 12 to the actuator port 1.

  Next, the operation of this embodiment will be described. Now, when the main spool MS is in the neutral position shown in the figure, the supply passage 3 is disconnected from the pump passage 12, and the return passage 4 is connected to the tank passage 13. Communication is interrupted. In addition, in this state, the pressure chamber 7 of the operation check valve V is also disconnected from the tank passage 13. Therefore, the load pressure guided to the actuator port 1 acts on the outer periphery of the valve body 5 and also acts on the cylinder portion 5 b in the pressure chamber 7. However, as described above, since the pressure receiving area of the cylinder portion 5b in the pressure chamber 7 is larger than the pressure receiving area of the outer periphery of the valve body 5 that closes the seat portion 6, the operation check valve V is kept closed. .

  When the main spool MS is moved from the neutral position to the right in the drawing, the supply passage 3 communicates with the pump passage 12 through the supply-side annular groove 10. Therefore, the pressure fluid supplied to the supply passage 3 passes through the load check valve 29 and pushes open the operation check valve V to be supplied from the actuator port 1 to the actuator.

  On the other hand, when the main spool MS is moved from the neutral position to the left in the drawing, first, the second port 15 communicates with the tank passage 13 via the annular groove 18. In this state, when the main spool MS is further moved leftward, the first port 14 is now communicated with the pressure chamber 7 via the flow path 17. Therefore, the load holding pressure of the pressure chamber 7 is guided to the pilot chamber 20 through the annular recess 24 and the control throttle 25.

  As described above, when the load holding pressure of the pressure chamber 7 is guided to the pilot chamber 20, since the spring chamber 21 is held at the tank pressure, the pilot spool PS moves against the spring force of the spring 22. When the pilot spool PS moves in this way, as shown in FIG. 2, the first port 14 and the second port 15 communicate with each other via the annular recess 24, so that the pressure chamber 7 is connected to the flow path 17 → first. It communicates with the tank passage 13 via the port 14 → the annular recess 24 → the second port 15. Therefore, the operation check valve V is opened by the load pressure acting on the pressure receiving area on the outer periphery of the valve body 5, the poppet portion 5 a opens the seat portion 6, and the working fluid of the actuator port 1 flows out to the return passage 4 side. Let

  As described above, the first port 14 and the flow path 17 communicate with each other, and at the same time, the third port 16 communicates with the return path 4, so that the fluid in the return path 4 flows into the pilot chamber 20. The fluid flowing into the pilot chamber 20 flows into the tank passage 13 via the control throttle 25 → the annular recess 24 → the second port 15 → the annular groove 18. When a flow is generated in the control throttle 25 as described above, a differential pressure is generated before and after the control throttle 25 and the upstream pressure acts on the pilot chamber 20.

  Therefore, the pilot spool PS maintains a position where the pressure in the pilot chamber 20 and the spring force of the spring 22 are balanced, and at the balance position, the opening degree of the second port 15 is controlled as shown in FIG. . Since the pilot spool PS maintains the balance position as described above, the opening degree of the second port 15 is controlled, and accordingly, the pressure in the pressure chamber 7 is also kept constant. As a result, the pressure in the pressure chamber 7 is kept constant and hunting of the operation check valve V is prevented.

In addition, since the inching control can be performed using the notch 19 while the pressure in the return passage 4 is stably maintained, the inching control can be performed smoothly. If the notch 19 is opened in the return passage 4 as described above, the flow rate proportional to the opening of the notch 19 can be returned to the tank passage 13.
Japanese Patent Application No. 2005-360741

  In the conventional apparatus as described above, since the orifice 8 provided in the operation check valve V is a fixed orifice, the flow rate flowing therethrough changes depending on the temperature and pressure of the fluid. When the flow rate flowing through the orifice 8 changes in this way, the initial operation of the pilot spool PS is not stable, and high-frequency vibration is generated, and there is a problem that abnormal noise is generated due to the vibration. The cause is as follows.

  In the above-described conventional apparatus, when the main spool MS is moved in the direction of returning the fluid from the left side of the drawing, that is, the actuator port 1, the pilot spool PS moves against the spring 22, but at this time, the annular recess of the pilot spool PS 24, the opening balance between the first port 14 and the second port 15 is maintained. The opening balance at this time depends on the opening area of the orifice 8 formed in the operation check valve V. That is, when the opening area of the orifice 8 is determined, at least the theoretical flow rate flowing therethrough is determined. Based on the theoretical values determined in this way, the first port 14 and the second port 15 The opening balance is maintained.

  However, the flow rate of the fluid flowing through the orifice 8 varies depending on the temperature and pressure. Therefore, even if it is designed in advance so as to keep the opening balance of the first and second ports 14 and 15 based on the theoretical value, it may not go as expected. If the flow rate flowing through the orifice 8 varies, the opening balance of the first and second ports 14 and 15 does not correspond to the fluid flow rate at that time. As described above, when the opening balance of the first and second ports 14 and 15 does not correspond to the flow rate at that time, the pilot spool PS vibrates at a high frequency and generates abnormal noise as described above.

  An object of the present invention is to provide an actuator control device that suppresses vibration of a pilot spool.

  According to the present invention, a main spool is slidably provided in the valve body, and an actuator port formed in the valve body is connected to a supply passage or a return passage according to a moving position of the main spool. The operation check valve is provided at the joining portion of the supply passage and the return passage, the operation check valve includes a seat portion provided at the joining portion of the supply passage and the return passage, a valve body incorporated in the valve body, A poppet part formed on the valve body for opening and closing the seat part, a pressure chamber facing the valve body on the opposite side of the poppet part, and a valve body formed on the valve body, wherein the actuator port communicates with the pressure chamber. And a spring that is provided in the pressure chamber and exerts a spring force in a direction in which the poppet portion is pressed against the seat portion. Actuator control device that increases the diameter of the valve body in the pressure chamber with respect to the opening diameter of the part and connects the pressure chamber to the tank passage or shuts off the communication according to the movement position of the main spool On the premise.

  Based on the above-described apparatus, the present invention incorporates a pilot spool having an annular recess formed in the main spool, and the first introduction port formed in the main spool is always in communication with the annular recess. The pilot spool has one end facing the pilot chamber provided in the main spool, the other end faces the spring chamber, and the pilot chamber is always in communication with the second introduction port formed in the main spool, The annular recess communicates with the annular recess through a communication passage formed in the pilot spool, and the annular recess is always in communication with the spring chamber via the control throttle, and the pilot spool is operated by the spring force of the spring provided in the spring chamber. While the spring chamber is closed when the The first spool and the pressure chamber, the spring chamber and the tank passage, the second inlet port and the return passage are disconnected from each other when the cylinder is kept in the neutral position, and the main spool is moved from the neutral position. When the working fluid is returned, the spring chamber communicates with the tank passage, the first introduction port communicates with the pressure chamber, the second introduction port communicates with the return passage, and the pilot spool Is provided with a control orifice in the communication process between the annular recess and the spring chamber, and the annular recess and the spring chamber are always communicated with each other through the control orifice. On the other hand, the pilot spool has a differential pressure before and after the control orifice. This is characterized in that the opening degree of the first introduction port is controlled so that the amount corresponding to the spring force is maintained.

  According to the present invention, since the flow rate flowing through the operation check valve pilot spool can be kept constant, the pilot spool does not vibrate at a high frequency and noise is not generated as in the prior art.

  In this embodiment, the structure of the operation check valve V and the pilot spool PS and the function thereof are different from the conventional ones, and the other configurations are the same as the conventional ones. Then, next, it demonstrates centering on a different point from the past.

  In the operation check valve V, a flow port 30 that is always in communication with the actuator port 1 is formed in the valve body 5, and a guide cylinder member 31 is fixed to the valve body 5. One end of the guide cylinder member 31 is closed to face the pressure chamber 7, and the other end is opened to the flow port 30 side.

  In the guide cylinder member 31 as described above, the control spool 32 is slidably incorporated, and a spring chamber 33 is defined between the control spool 32 and the closed portion of the guide cylinder member 31, and this spring A spring 34 is provided in the chamber 33. Further, the control spool 32 is formed with a control orifice 35 that is always in communication with the flow port 30 and a communication path 36 that is always in communication with the control orifice 35, and the control orifice 35 and the communication path 36 are combined to control the control spool 35. The center portion of the spool 32 is configured to penetrate.

  In addition, a variable orifice 37 is formed in the control spool 32, and the opening of the variable orifice 37 is variable according to the relative position with respect to the control port 38 formed in the guide cylinder member 31. That is, when the control spool 32 is at the normal position shown in the drawing, the relative position of the control port 38 coincides with that at the maximum opening. When the control spool 32 moves against the spring 34, the relative position between the variable orifice 37 and the control port 38 is shifted, and the opening degree of the variable orifice 37 is reduced.

  The configuration of the valve body 5 of the operation check valve V is exactly the same as the conventional one. That is, the pressure receiving area of the cylinder portion 5 b in the pressure chamber 7 is larger than the pressure receiving area of the outer periphery of the valve body 5 that closes the seat portion 6.

On the other hand, a first introduction port 39 and a second introduction port 40 are formed in the main spool MS incorporating the pilot spool PS.
The first introduction port 39 is disconnected from the flow path 17 when the main spool MS is in the neutral position shown in the figure. In other words, when the main spool MS is in the neutral position, the first introduction port 39 is disconnected from the pressure chamber 7. When the main spool MS moves in the left direction of the drawing, that is, in the direction in which the working fluid is returned, the main spool MS opens to the flow path 17 and communicates with the pressure chamber 7.

  The second introduction port 40 is always in communication with the pilot chamber 20, and when the main spool MS is in the neutral position shown in the figure, the communication with the return passage 4 is interrupted, but the main spool MS is operated in the left direction of the drawing, that is, the operation. When the fluid moves in the return direction, the return passage 4 opens. The timing at which the second introduction port 40 communicates with the return passage 4 and the timing at which the first introduction port 39 opens into the flow path 17 as described above are substantially the same.

  Further, the pilot spool PS is the same as the conventional one in that an annular recess 24 is formed between the first land portion 26 and the second land portion 27. However, in this embodiment, the pilot spool PS is annular with the pilot chamber 20. In the process of communicating with the recess 24, an element that exhibits a throttling function is not provided in particular, and the pilot chamber 20 and the annular recess 24 are communicated with each other via the communication path 41. The second land portion 27 controls the opening degree of the first introduction port 39 according to the movement position of the pilot spool PS. The first introduction port 39 and the second land portion 27 are combined to make a variable orifice. It constitutes.

The pilot spool PS is formed with a control orifice 42 that is always open to the annular recess 24, and the annular recess 24 is always in communication with the spring chamber 21 via the control orifice 42.
The configuration other than the above is the same as that of the conventional apparatus.

  Next, the operation of this embodiment will be described. First, when the main spool MS is moved in the left direction in the drawing, the communication passage 23 is first opened in the annular groove 18 and the spring chamber 21 is communicated with the tank passage 13 as in the prior art. When the main spool MS is further moved to the left in the drawing from this state, the first introduction port 39 opens to the flow path 17 and the second introduction port 40 opens to the return passage 4.

  If the first introduction port 39 opens to the flow path 17 as described above, the pressure chamber 7 passes through the flow path 17 → the first introduction port 39 → the annular recess 24 → the control orifice 42 → the spring chamber 21 and the tank passage. 13 communicates. Accordingly, a flow is also generated in the control orifice 35 of the operation check valve V, and a pressure loss is generated by this flow. Accordingly, the pressure upstream of the control orifice 35 acts on one end of the control spool 32, that is, the end opposite to the spring chamber 33. Due to the pressure acting on one end of the control spool 32, the control spool 32 moves against the spring 34 and controls the opening of the variable orifice 37. That is, the control spool 32 controls the opening degree of the variable orifice 37 so that the differential pressure across the control orifice 35 becomes equal to the spring force of the spring 34. In this way, the differential pressure before and after the control orifice 35 is always kept constant, so that the flow rate through the control orifice 35 is also controlled to be constant. In other words, the flow rate flowing through the control orifice 35 can be kept constant regardless of the temperature and pressure of the working fluid.

  The constant flow rate controlled as described above flows into the tank passage 13 via the control orifice 42 as described above. If a flow is generated in the control orifice 42 in this way, a pressure loss occurs there, and the pressure on the upstream side of the control orifice 42 acts on the pilot chamber 20. Therefore, the control spool 32 moves against the spring 22 and controls the opening degree of the first introduction port 39 by the second land portion 27. That is, the opening degree of the first introduction port 39 is controlled so that the differential pressure across the control orifice 42 is constant.

  Therefore, according to this embodiment, the flow rate flowing through the control orifice 35 of the operation check valve V is kept constant, and the pilot spool PS returns a constant flow rate to the tank passage 13 with respect to the constant flow rate. As a result, the design can always assume a constant control flow rate. If a constant control flow rate can be assumed as described above, it is easy to stabilize the movement of the pilot spool PS in terms of design. Therefore, the movement of the pilot spool PS can be stabilized, and the pilot spool PS can be prevented from vibrating at a high frequency as in the prior art.

  It should be noted that it is appropriate to increase the flow rate between the flow rate Q1 controlled by the control spool 32 on the operation check valve V side and the flow rate Q2 controlled by the pilot spool PS on the main spool MS side. Q1 ≧ Q2 is generally considered, although it depends on the mounting conditions and control conditions.

It is sectional drawing of the state which maintained the main spool in the neutral position. FIG. 10 is a cross-sectional view showing a conventional device in a state where a main spool is kept in a neutral position. In the conventional apparatus, it is sectional drawing of the state which switched the main spool to drawing left position.

Explanation of symbols

B Valve body 1 Actuator port MS Main spool V Operation check valve 3 Supply passage 4 Return passage 5 Valve body 5a Poppet portion 6 Seat portion 7 Pressure chamber 9 Spring 13 Tank passage PS Pilot spool 20 Pilot chamber 21 Spring chamber 24 Annular recess 25 Control Restriction 39 First introduction port 40 Second introduction port 41 Communication passage 42 Control orifice

Claims (1)

  A main spool is slidably provided in the valve body, and an actuator port formed in the valve body communicates with the supply passage or communicates with the return passage according to the movement position of the main spool. An operation check valve is provided at the junction between the supply passage and the return passage. The operation check valve includes a seat provided at the junction between the supply passage and the return passage, a valve body incorporated in the valve body, and a valve body. A poppet part that opens and closes the seat part, a pressure chamber facing the valve body on the opposite side of the poppet part, an orifice that is formed in the valve body and communicates the actuator port and the pressure chamber; A spring provided in the pressure chamber to exert a spring force in a direction in which the poppet portion is pressed against the seat portion, and the opening diameter of the seat portion is provided. On the other hand, in the actuator control device that increases the diameter of the valve body in the pressure chamber and connects the pressure chamber to the tank passage or blocks the communication according to the movement position of the main spool. In the pilot chamber, a pilot spool having an annular recess is incorporated, and the first introduction port formed in the main spool is always in communication with the annular recess, and one end of the pilot spool is provided in the main spool. The pilot chamber is always in communication with a second introduction port formed in the main spool, and the pilot chamber is connected via a communication passage formed in the pilot spool. The annular recess communicates with the annular recess. The spring chamber is closed when the pilot spool holds the normal position by the action of the spring force of the spring provided in the spring chamber, and the main spool is kept in the neutral position. The communication between the first introduction port and the pressure chamber, the spring chamber and the tank passage, the second introduction port and the return passage is blocked, and the main spool is moved from the neutral position in the direction of returning the working fluid. The spring chamber communicates with the tank passage, the first introduction port communicates with the pressure chamber, the second introduction port communicates with the return passage, and the pilot spool includes the annular recess and the spring chamber. A control orifice is provided in the communication process with the annular recess, and the annular recess and the spring chamber are always communicated with each other through the control orifice. The actuator spool is configured to control the opening degree of the first introduction port so that the differential pressure before and after the control orifice is maintained at an amount corresponding to the spring force of the spring chamber.

Images