JP3573484B2 - Hydraulic control valve - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an improvement of a hydraulic control valve used for an industrial machine, a construction machine, and the like.
[0002]
[Prior art]
BACKGROUND ART As a conventional hydraulic control valve used for an industrial machine such as an injection molding machine or a press machine, or a construction machine such as an excavator or a crane, there is one shown in FIG. 5, for example.
[0003]
Describing this, the hydraulic control valve 10 is interposed in the middle of the hydraulic passage 12 connecting the hydraulic pump 11 and the hydraulic cylinder 13. The control device of the hydraulic control valve 10 controls the opening cross-sectional area of the hydraulic passage 12 determined by the stroke position of the poppet valve 20, and based on the pressure difference between the upstream side and the downstream side of the poppet valve 20 at this time, The poppet valve 20 is controlled so as to match the target while controlling the flow rate of the hydraulic oil to be sent or detecting the pressure downstream of the poppet valve 20.
[0004]
The hydraulic control valve 10 has a columnar poppet valve 20 slidably disposed inside a cylindrical housing 30. The housing 30 has a port 31 communicating with the hydraulic pump 11 and a port 32 communicating with the hydraulic cylinder 13.
[0005]
A stepped portion 23 is formed on the outer periphery of the poppet valve 20. The poppet valve 20 is formed by reducing the diameter from a large diameter portion 24 having a diameter D1 to a small diameter portion 27 having a diameter D2 via an annular stepped portion 23.
[0006]
The first pilot chamber 1 is defined between the first stepped portion 23 of the poppet valve 20 and the housing 30. As the first pilot chamber 1 expands, the poppet valve 20 is displaced in the valve opening direction.
[0007]
A circuit 14 for communicating the first pilot chamber 1 with the hydraulic pump 11 is provided.
[0008]
A second pilot chamber 2 is defined between one end of the poppet valve 20 and the housing 30. As the second pilot chamber 2 expands, the poppet valve 20 is displaced in the valve closing direction.
[0009]
The circuit 15 connected to the second pilot chamber 2 is selectively connected to the hydraulic pump 11 and the tank 17 via the proportional solenoid valve 7. The proportional solenoid valve 7 has a position a that connects the second pilot chamber 2 to the hydraulic pump 11, a position b that connects the second pilot chamber 2 to the tank 17, and a position c that closes the second pilot chamber 2. .
[0010]
A return spring 9 for urging the poppet valve 20 in the closing direction is interposed.
[0011]
When the proportional solenoid valve 7 is switched to the position a where the second pilot chamber 2 communicates with the hydraulic pump 11, the hydraulic pressure P2 guided to the second pilot chamber 2 increases, and the hydraulic pressure generated in the second pilot chamber 2 ( π / 4) The resultant force of D12 × P2 and the urging force Fs of the return spring 9 becomes the force for urging the poppet valve 20 in the valve closing direction.
[0012]
At this time, the force for urging the poppet valve 20 in the valve opening direction is a combined force of the oil pressure acting on the valve body 21 of the poppet valve 20 and the oil pressure generated in the first pilot chamber 1.
[0013]
Assuming that the oil pressure acting on the valve body 21 of the poppet valve 20 and the oil pressure guided to the first pilot chamber 1 have substantially the same value P1 in the vicinity of the fully opened position of the poppet valve 20, the force acting on the poppet valve 20 is balanced. Is Fs + (π / 4) D12 × P2 = (π / 4) D12 × P1 (2)
Is represented as
[0014]
[Problems to be solved by the invention]
However, in such a conventional hydraulic control valve 10, near the fully opened position of the poppet valve 20, the hydraulic pressure acting on the valve body 21 of the poppet valve 20, the hydraulic pressure guided to the first pilot chamber 1, and When the hydraulic pressures guided to the second pilot chamber 2 become substantially equal, the hydraulic pressure (π / 4) D12 × P2 generated in the second pilot chamber 2 becomes equal to the hydraulic pressure acting on the valve body 21 of the poppet valve 20 and the second hydraulic pressure. The force that drives the poppet valve 20 in the valve closing direction, which is offset by the resultant force (π / 4) D12 × P1 of the hydraulic pressure generated in one pilot chamber 1, is as small as only the urging force Fs of the return spring 9.
[0015]
FIG. 3 is a characteristic diagram showing the relationship between the differential pressure ΔP between P1 and P2 and the flow rate q passing through the proportional solenoid valve 7. The flow rate q increases as the exciting current of the proportional solenoid valve 7 increases to i1, i2, and i3, but the increase characteristic of the flow rate q is non-linear.
[0016]
When the force for driving the poppet valve 20 in the valve closing direction is as small as only the urging force Fs of the return spring 9, the differential pressure ΔP between P1 and P2 is given by the following equation (2): ΔP = P1−P2 = Fsp / (π / 4) D12 ... (3)
Since ΔP is also small, and therefore the flow rate q passing through the proportional solenoid valve 7 is small, the speed in the closing direction is low.
[0017]
For this reason, for example, when the poppet valve 20 is fully closed in order to hold the load from a state where the poppet valve 20 is opened, it takes time until the poppet valve 20 is completely closed, resulting in poor responsiveness. There is a problem.
[0018]
The present invention has been made in view of the above problems, and has as its object to improve the responsiveness at the time of a valve closing operation in a hydraulic control valve.
[0019]
[Means for Solving the Problems]
According to the first aspect of the present invention, at one end of the poppet valve, a valve body for changing a cross-sectional area of a passage communicating an oil pressure source and an actuator is formed in accordance with the stroke position, and the poppet valve is closed by the other end of the poppet valve. Defining a second pilot chamber that expands when displaced in the direction, including valve means for selectively communicating the second pilot chamber with the hydraulic source and the tank side, with a first step formed on the outer periphery of the poppet valve The first portion defines a first pilot chamber that expands when the poppet valve is displaced in the valve opening direction, a circuit that communicates the first pilot chamber with a hydraulic pressure source is provided, and the poppet valve is biased in the valve closing direction. A circuit that has a return spring interposed, defines a drain chamber that expands when the poppet valve is displaced in the valve opening direction by a second stepped portion formed on the outer periphery of the poppet valve, and connects the drain chamber to the tank side. Distribute To.
[0020]
[Action]
In the hydraulic control valve according to the present invention, the hydraulic pressure acting on the valve body of the poppet valve and the hydraulic pressure generated in the first pilot chamber act on the poppet valve in the opening direction. The hydraulic pressure generated in the second pilot chamber and the urging force of the return spring act in the closing direction.
[0021]
When the valve means communicates the second pilot chamber to the tank side, the hydraulic pressure generated in the second pilot chamber decreases, and the hydraulic pressure acting on the valve body of the poppet valve and the hydraulic pressure generated in the first pilot chamber are reduced. The resultant force quickly displaces the poppet valve in the opening direction against the urging force of the return spring.
[0022]
When the valve means communicates the second pilot chamber with the hydraulic pressure source, the hydraulic pressure generated in the second pilot chamber increases, and the hydraulic pressure acting on the valve body of the poppet valve and the hydraulic pressure generated in the first pilot chamber increase. The poppet valve is displaced in the closing direction against the resultant force.
[0023]
By defining the drain chamber by the second stepped portion formed on the outer periphery of the poppet valve, the pressure receiving area where the hydraulic pressure acts on the valve body of the poppet valve is reduced, and the poppet valve is closed in the valve closing direction by that much. The driving force can be increased. As a result, in the state where the valve means communicates the second pilot chamber with the hydraulic pressure source and the hydraulic pressure generated in the second pilot chamber is increased, the speed at which the poppet valve closes is increased, and the operation response of the poppet valve is increased. You can enhance the nature.
[0024]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0025]
As shown in FIGS. 1 and 2, the hydraulic passage 12 connects a hydraulic pump 11 provided as a hydraulic source and a hydraulic cylinder 13 provided as an actuator. The hydraulic control valve 10 interposed in the hydraulic passage 12 adjusts the pressure and flow rate of the hydraulic oil guided to the hydraulic cylinder 13.
[0026]
The hydraulic control valve 10 has a columnar poppet valve 20 slidably disposed inside a cylindrical housing 30. The housing 30 has a port 31 communicating with the hydraulic pump 11 and a port 32 communicating with the hydraulic cylinder 13. The port 31 is formed coaxially with the poppet valve 20, and the port 32 is formed orthogonal to the port 31.
[0027]
The poppet valve 20 has a cylindrical valve body 21 formed at one end thereof, and the valve body 21 has a cutout 22 formed in a wedge shape toward the tip thereof. When the poppet valve 20 is closed, as shown in FIG. 2, the valve body 21 is fitted into the port 31, and the hydraulic passage 12 is completely closed. As the poppet valve 20 is displaced from the fully closed position in the opening direction, the cross-sectional area where the wedge-shaped notch 22 opens to the port 32 gradually increases, and the opening cross-sectional area of the hydraulic passage 12 increases. I have.
[0028]
Note that, for example, a plurality of holes may be formed in the valve body portion 21, and the poppet valve 20 may be configured such that the number of holes opened to the port 32 increases as the poppet valve 20 is displaced in the opening direction from the fully closed position. .
[0029]
A first stepped portion 23 is formed on the outer periphery of the poppet valve 20. The poppet valve 20 is formed by reducing the diameter from a large diameter portion 24 having a diameter D1 to a medium diameter portion 25 having a diameter D3 via an annular first stepped portion 23.
[0030]
The first pilot chamber 1 is defined between the first stepped portion 23 of the poppet valve 20 and the housing 30. As the first pilot chamber 1 expands, the poppet valve 20 is displaced in the valve opening direction.
[0031]
A circuit 14 for communicating the first pilot chamber 1 with the hydraulic pump 11 is provided.
[0032]
A second pilot chamber 2 is defined between one end of the poppet valve 20 and the housing 30. As the second pilot chamber 2 expands, the poppet valve 20 is displaced in the valve closing direction.
[0033]
The circuit 15 connected to the second pilot chamber 2 selectively communicates with the hydraulic pump 11 and the tank 17 via the proportional solenoid valve 7. The proportional solenoid valve 7 has a position a that connects the second pilot chamber 2 to the hydraulic pump 11, a position b that connects the second pilot chamber 2 to the tank 17, and a position c that closes the second pilot chamber 2. .
[0034]
A second stepped portion 26 is formed on the outer periphery of the poppet valve 20. The poppet valve 20 is formed by reducing the diameter from the middle diameter portion 25 of the diameter D3 to the small diameter portion 27 of the diameter D2 via the annular second stepped portion 26. That is, the poppet valve 20 is formed by gradually reducing the diameter of the large-diameter portion 24, the intermediate-diameter portion 25, and the small-diameter portion 27, and has a dimensional relationship of D1>D3> D2.
[0035]
A drain chamber 3 is defined between the second stepped portion 26 of the poppet valve 20 and the housing 30. When the drain chamber 3 is enlarged, the poppet valve 20 is displaced in the valve opening direction.
[0036]
A circuit 16 that connects the drain chamber 3 to a tank 17 is provided.
[0037]
A return spring 9 for urging the poppet valve 20 in the closing direction is interposed. One end of the return spring 9 contacts the poppet valve 20 and the other end is supported by a retainer provided on the housing 30 side.
[0038]
When the pump discharge pressure is reduced due to the stoppage of the operation of the hydraulic pump 11 or the like, when the proportional solenoid valve 7 is switched to the position a where the second pilot chamber 2 communicates with the hydraulic pump 11, the poppet valve 20 is attached with the return spring 9. The valve is closed by the force.
[0039]
A displacement sensor 41 for detecting the stroke position of the poppet valve 20 is provided. Two pressure sensors are provided for detecting the pressures on the upstream and downstream sides of the valve body 21 of the poppet valve 20, respectively. The control device selectively controls the flow rate and the pressure by the hydraulic control valve.
[0040]
At the time of the flow rate control, the opening cross-sectional area of the hydraulic passage 12 determined by the stroke position of the poppet valve 20 is controlled, and the flow rate of the working oil sent to the hydraulic cylinder 13 from the detected pressures on the upstream and downstream sides of the poppet valve 20 is set to a target value. To match.
[0041]
At the time of pressure control, the position of the poppet valve 20 is controlled such that the detected downstream pressure matches the target.
[0042]
When the proportional solenoid valve 7 is switched to the position b where the second pilot chamber 2 communicates with the tank 17, the pressure P 2 guided to the second pilot chamber 2 decreases, and the oil acting on the valve body 21 of the poppet valve 20. The poppet valve 20 is quickly displaced in the opening direction while compressing the return spring 9 by the combined force of the pressure and the hydraulic pressure generated in the first pilot chamber 1. Thereby, the opening cross-sectional area of the hydraulic passage 12 is increased, and the hydraulic pressure or the flow rate of the hydraulic oil sent to the hydraulic cylinder 13 is increased.
[0043]
When the proportional solenoid valve 7 is switched to the position c for closing the second pilot chamber 2, the stroke displacement of the poppet valve 20 is stopped.
[0044]
When the proportional solenoid valve 7 is switched to the position a where the second pilot chamber 2 communicates with the hydraulic pump 11, the hydraulic pressure P2 guided to the second pilot chamber 2 increases, and the hydraulic pressure generated in the second pilot chamber 2 ( π / 4) The resultant force of D12 × P2 and the urging force Fs of the return spring 9 becomes the force for urging the poppet valve 20 in the valve closing direction.
[0045]
At this time, the force urging the poppet valve 20 in the valve opening direction includes the hydraulic pressure acting on the valve body 21 of the poppet valve 20, the hydraulic pressure generated in the first pilot chamber 1, and the hydraulic pressure in the drain chamber 3. Is the result.
[0046]
In the vicinity of the fully opened position of the poppet valve 20, the hydraulic pressure acting on the valve body 21 of the poppet valve 20 and the hydraulic pressure guided to the first pilot chamber 1 are assumed to be substantially equal to P1, and the pressure of the drain chamber 3 is measured by a gauge. Assuming that the pressure is 0, the balance equation of the force acting on the poppet valve 20 is expressed as Fs + (π / 4) D12 × P2 = (π / 4) {D12− (D32−D22)} × P1 (1) You.
[0047]
Compared with the balance formula (2) for the force acting on the poppet valve 20 in the conventional apparatus, the force for urging the poppet valve 20 in the closing direction is increased by (π / 4) (D32−D22) × P1.
[0048]
That is, by defining the drain chamber 3 by the second stepped portion 26 formed on the outer periphery of the poppet valve 20, the pressure receiving area where the oil pressure acts on the valve body 21 of the poppet valve 20 is reduced by the second stepped portion. 26 is reduced, and the force for driving the poppet valve 20 in the valve closing direction can be increased by that amount.
[0049]
FIG. 3 is a characteristic diagram showing the relationship between the differential pressure ΔP between P1 and P2 and the flow rate q passing through the proportional solenoid valve 7. The flow rate q increases as the exciting current of the proportional solenoid valve 7 increases to i1, i2, and i3, but the increase characteristic of the flow rate q is non-linear. When the proportional solenoid valve 7 is switched to the position a where the second pilot chamber 2 is communicated with the hydraulic pump 11, the flow rate q passing through the proportional solenoid valve 7 increases as the differential pressure ΔP between P1 and P2 increases. As a result, the speed at which the poppet valve 20 is closed can be increased, and the operation responsiveness of the poppet valve 20 can be increased.
[0050]
Next, another embodiment shown in FIG. 4 will be described. Note that the same reference numerals are used for the portions corresponding to those in FIG.
[0051]
A first stepped portion 23 and a second stepped portion 26 are respectively formed on the outer periphery of the poppet valve 20. Poppet valve 20, the large diameter portion 24 of diameter D1, via the first stepped portion 23 of the annular, reduced in diameter to diameter 25 in the diameter D3, the intermediate-diameter portion 25, the second stage of the cyclic The diameter is reduced to a small diameter portion 27 having a diameter D2 via the attachment portion 26. That is, the poppet valve 20 is formed by gradually reducing the diameter of the large-diameter portion 24, the intermediate-diameter portion 25, and the small-diameter portion 27, and has a dimensional relationship of D1>D3> D2.
[0052]
The drain chamber 3 is defined between the first stepped portion 23 and the housing 30. When the drain chamber 3 is enlarged, the poppet valve 20 is displaced in the valve opening direction. A circuit 16 that connects the drain chamber 3 to a tank 17 is provided.
[0053]
The first pilot chamber 1 is defined between the second stepped portion 26 and the housing 30. As the first pilot chamber 1 expands, the poppet valve 20 is displaced in the valve opening direction. A circuit 14 for communicating the first pilot chamber 1 with the hydraulic pump 11 is provided.
[0054]
In this case, by defining the drain chamber 3 by the first stepped portion 23 formed on the outer periphery of the poppet valve 20, the pressure receiving area where the hydraulic pressure acts on the valve body portion 21 of the poppet valve 20 has the second stepped portion. The amount corresponding to the portion 26 is reduced, and the force for driving the poppet valve 20 in the valve closing direction can be increased accordingly.
[0055]
【The invention's effect】
As described above, according to the first aspect of the present invention, a valve body for changing a cross-sectional area of a passage communicating an oil pressure source and an actuator is formed at one end of a poppet valve according to a stroke position of the poppet valve. A second pilot chamber that expands when the poppet valve is displaced in the valve closing direction is defined, and a valve means for selectively communicating the second pilot chamber with the hydraulic pressure source and the tank side is formed on the outer periphery of the poppet valve. The first stepped portion defines a first pilot chamber that expands when the poppet valve is displaced in the valve opening direction, a circuit that connects the first pilot chamber to a hydraulic pressure source is provided, and the poppet valve is closed. A return spring that biases the poppet valve is interposed, and a second stepped portion formed on the outer periphery of the poppet valve defines a drain chamber that expands when the poppet valve is displaced in the valve opening direction. ~ side Because it was provided with circuitry which communicates, increased the power to drive only poppet valve correspondingly defining a drain chamber in a valve closing direction by the stepped portion is increased responsiveness of the poppet valve is closed operation.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a hydraulic control valve showing an embodiment of the present invention.
FIG. 2 is a sectional view of the hydraulic control valve.
FIG. 3 is a flow rate characteristic diagram of the hydraulic control valve.
FIG. 4 is a configuration diagram of a hydraulic control valve showing another embodiment.
FIG. 5 is a configuration diagram of a hydraulic control valve showing a conventional example.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 first pilot chamber 2 second pilot chamber 3 drain chamber 7 proportional solenoid valve 9 return spring 11 hydraulic pump 12 hydraulic passage 13 hydraulic cylinder 14 circuit 15 circuit 17 tank 20 poppet valve 21 valve body 26 second stepped part 30 housing

Claims (1)

At one end of the poppet valve, a valve body that changes the cross-sectional area of the passage communicating the hydraulic power source and the actuator according to the stroke position is formed, and expands when the poppet valve is displaced in the closing direction by the other end of the poppet valve. A second pilot chamber is defined, and a valve means for selectively communicating the second pilot chamber with the hydraulic pressure source and the tank side is provided. The poppet valve is opened in a valve opening direction by a first stepped portion formed on the outer periphery of the poppet valve. Defining a first pilot chamber that expands when displaced, a circuit connecting the first pilot chamber to a hydraulic pressure source, a return spring for urging the poppet valve in a valve closing direction, and a poppet The second stepped portion formed on the outer periphery of the valve defines a drain chamber that expands when the poppet valve is displaced in the valve opening direction, and a circuit that connects the drain chamber to the tank side is provided. Do Pressure control valve.

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