JP3312961B2 - Proportional solenoid control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a proportional electromagnetic type flow control valve and pressure control valve used in a hydraulic circuit.

[0002]

2. Description of the Related Art As a control valve used for controlling the speed of a hydraulic cylinder or the like, a proportional electromagnetic flow control valve that adjusts the opening degree of a valve based on a set flow rate is known. As shown in FIG. 6, this proportional electromagnetic flow control valve is a flow control valve 91.
And a pressure sensor 93, 94 for detecting the pressure Pa, Pb at the inlet / outlet of the valve. The flow rate calculation circuit 95 is provided with a differential pressure (| Pa) between the pressure sensors 93, 94. −Pb |) and the valve opening X of the displacement sensor 92 (that is, the opening area), and the control flow circuit 96 controls the valve opening Xr so that the flow Q becomes equal to the flow command signal Qr. The flow control valve 91 is driven to a predetermined valve opening degree by exciting a solenoid (not shown) based on a command signal Xr of the control circuit 97. The flow control valve 91 increases the valve opening X when the flow rate Q is smaller than the flow rate command signal Qr, and decreases the valve opening X when the flow rate Q is larger than the flow rate command signal Qr.

[0003] Such a flow control valve 91 can be used not only for flow control but also for pressure control such as load pressure of a hydraulic cylinder. FIG. The outlet side of the flow control valve 91 is connected to the tank 12 via the hydraulic cylinder 14 and the orifice, and the outlet pressure Pb is fed back to the control operation circuit 96 so that the outlet pressure Pb becomes equal to the pressure command Pbr. The opening X is controlled. When the outlet pressure Pb is smaller than the pressure command Pbr, the valve opening X is increased. On the other hand, when the outlet pressure Pb is larger than the pressure command Pbr, the valve opening X is decreased.

On the other hand, when performing meter-out pressure control, the same control can be performed by setting the detected pressure of the pressure sensor 94 to the inlet pressure Pb, as shown in FIG. If smaller than command Pbr, valve opening X
And if the inlet pressure Pb is greater than the pressure command Pbr, the valve opening X is increased.

[0005]

However, the flow rate control valve 91 can control either the flow rate or the pressure, but cannot control both the flow rate and the pressure with one valve. When controlling the flow rate and the pressure in the hydraulic circuit, respectively, a control valve for the flow rate and a control valve for the pressure are required, which increases the number of parts, complicates the configuration of the hydraulic circuit, and increases the manufacturing cost. There was a case.

Accordingly, an object of the present invention is to provide a proportional electromagnetic control valve capable of controlling the flow rate and pressure with one valve.

[0007]

As shown in FIG. 1, the present invention provides a valve 51 whose opening changes according to a signal, a means 52 for detecting the opening X of the valve 51, an inlet and an outlet of the valve. Means 53, 54 for detecting the pressures Pa, Pb of
Means 55 for calculating the flow rate Q from the pressure difference between the detected pressure and the detected opening degree X of the valve; means for calculating the control signal Qc based on the flow rate from the calculation result of the flow rate Q and the flow rate command signal Qr 56, means 57 for calculating a control signal Qp based on pressure from the detected pressure Pb at the outlet and the pressure command signal Pbr, means 61 for comparing the flow rate command signal Qr with the calculated flow rate Q, the pressure command signal Pbr Means for comparing the flow direction of either the meter-in or meter-out of the valve, and means 58 for instructing the flow direction of either the meter-in or meter-out of the valve. If the flow rate command signal Qr is greater than the calculated flow rate Q or if the outlet pressure Pb is greater than the pressure command signal Pbr during flow rate control, the control signal Q based on pressure is used.
p, otherwise, the control signal Qc based on the flow rate is selected, while if the direction command is meter-out, if the outlet pressure Pb is greater than the pressure command signal Pbr in the comparison result, the control signal Qp based on the pressure is selected. If not, means 59 for selecting control signal Qc based on flow rate
And means 60 for driving the valve 51 based on the selected control signal.

[0008]

Therefore, in FIG. 1, the flow rate calculating means 55 determines the flow rate Q passing through the valve 51 from the difference between the pressures Pa and Pb at the inlet and outlet of the valve 51 and the opening degree X of the valve 51. The control signal calculating means 56 calculates a control signal Qc based on the flow rate from the flow rate Q and the flow rate command signal Qr, and the control signal calculating means 57 calculates a control signal Qp based on the pressure based on the outlet pressure Pb and the pressure command signal Pbr. Calculate. Further, the comparing means 61 compares the flow command signal Qr with the magnitude of the flow Q, the comparing means 62 compares the outlet pressure Pb with the pressure command signal Pbr, and the selecting means 59 selects the direction command means 5.
When the direction command Dir 8 is meter-in, the comparison means 6
The flow rate command signal Qr is larger than the calculated flow rate Q during pressure control or the outlet pressure Pb during flow rate control based on the comparison results of 1, 62.
Is larger than the pressure command signal Pbr, the control signal Qp based on the pressure is selected. Otherwise, the control signal Qc based on the flow rate is selected. On the other hand, when the direction command Dir is meter-out, the outlet pressure Pb is determined in the comparison result. Is larger than the pressure command signal Pbr, the control signal Qp based on the pressure is
Otherwise, the control signal Qc based on the flow rate is selected, and the valve driving means 60 drives the valve 51 based on the selection result of the selection means 59. Therefore, the flow rate Q and the flow rate command signal Qr, the outlet pressure Pb and the pressure command signal Pbr It is possible to automatically switch between the flow control and the pressure control in accordance with the magnitude of.

[0009]

FIG. 2 shows an embodiment of the present invention.

In FIG. 2, a valve unit 10 constituting a proportional electromagnetic control valve has an inlet port 10A having a hydraulic power source 1
1, a load (not shown) is connected to the outlet port 10B, and a meter-in hydraulic circuit is formed in which a part of the pressure of the outlet port 10B is returned to the tank 12 via an orifice (not shown).

A control valve 1 for changing the opening degree of the valve according to a signal is housed in the valve unit 10 and connected to an inlet port 10A and an outlet port 10B. The control valve 1 is driven by a solenoid (not shown).

The control valve 1 is provided with a displacement sensor 2 for detecting the opening X of the valve, and a pressure sensor 3 for detecting the inlet pressure Pa is provided on the inlet port 10A side of the control valve 1, while the control valve 1 A pressure sensor 4 for detecting the outlet pressure Pb is provided on the side of the outlet port 10B.

The outputs Pa and Pb of the pressure sensors 3 and 4 and the output X of the displacement sensor 2 are input to a command selection control circuit 22 and a flow rate calculation circuit 21 of a controller constituted by a microprocessor or the like.

The command selection control circuit 22 computes and selects a control signal Xq based on these sensor outputs, a direction command Dir from a direction command means (not shown), a flow rate command signal Qr and a pressure command signal Pbr from a command means (not shown). The control operation circuit 23 outputs the control signal X
The valve drive circuit 24 drives the control valve 1 based on the valve opening calculated based on q and the detected opening X of the displacement sensor 2.

The direction command means (not shown) is a control valve 1
, Ie, the direction of meter-in and meter-out, and is constituted by, for example, a changeover switch.

Next, the contents of control by the controller will be described with reference to the flowchart shown in FIG.

In step S1, the inlet pressure Pa and outlet pressure Pb of the pressure sensors 3 and 4 and the valve opening X of the displacement sensor 2 are read, and a direction command Dir from a direction command means (not shown) is read.

Inlet pressure P of the read pressure sensors 3 and 4
a, the flow rate Q of the hydraulic oil passing through the control valve 1 is calculated from the outlet pressure Pb and the detected opening X of the displacement sensor 2 (step S).
2).

In calculating the flow rate, first, the differential pressure ΔP between the inlet pressure Pa and the outlet pressure Pb is calculated by the following equation.

ΔP = Pa−Pb Next, since the opening area corresponding to the valve opening X of the control valve 1 is known, the relationship between the preset valve opening X and the opening area A (x) and The flow rate Q is calculated from the differential pressure ΔP between the inlet pressure Pa and the outlet pressure Pb by the following equation.

[0021]

(Equation 1)

A flow rate command signal Q from a command means (not shown)
r (step S3), and the control signal Qc based on the flow rate is calculated from the calculated flow rate Q and the read flow rate command signal Qr.
Is calculated (step S4).

The control signal Qc based on the flow rate is obtained by the following equation.

Qc = Qr-Q On the other hand, the pressure command signal Pbr is read (step S5),
A control signal Qp based on the pressure is calculated from the pressure command signal Pbr and the outlet pressure Pb (step S6).

The control signal Qp based on this pressure is obtained by the following equation.

Qp = Pbr-Pb Here, a conditional branch is made by the direction command Dir read in step S1, and the direction command Dir = “meter-in”
If so, the process proceeds to step S8, and if the direction command Dir = “meter out”, the process proceeds to step S12 (step S7).

When the direction command Dir is meter-in, the processing of steps S8 to S11 described below is performed.

Next, it is determined whether the current control is pressure control or flow rate control (step S70). If pressure control is performed, the process proceeds to step S8.
Proceed to step 10.

Then, the flow command signal Qr is compared with the calculated flow Q (step S8), and the flow command signal Qr
Is greater than the flow rate Q, the flow proceeds to step S9, and if the flow rate command signal Qr is equal to or less than the flow rate Q, the flow proceeds to step S10.

If the flow command signal Qr is larger than the flow rate Q, the control signal Xq is set to a pressure-based control signal Qp. (Step S9) If the flow command signal Qr is equal to or less than the flow Q, step S10.
To compare the outlet pressure Pb with the pressure command signal Pbr. If the outlet pressure Pb is larger than the pressure command signal Pbr, the control signal Qp based on the pressure is set to the control signal Xq in step S9, while the outlet pressure P
If b is equal to or less than the pressure command signal Pbr, the control signal Qc based on the flow rate is set as the control signal Xq in step S11.

On the other hand, when the direction command Dir is meter-out in the conditional branch of step S7, the processing of steps S12 to S14 described below is performed.

In step S12, the outlet pressure Pb is compared with the pressure command signal Pbr. If the outlet pressure Pb is larger than the pressure command signal Pbr, in step S13 the control signal Qp based on the pressure is set to the control signal Xq, while the outlet pressure Pb Is the pressure command signal P
If br or less, the control signal Qc based on the flow rate is set as the control signal Xq in step S14.

Thus, when the direction command Dir is meter-in and pressure control is performed, the flow rate command signal Qr is larger than the calculated flow rate Q or the outlet pressure Pb is changed to the pressure command signal Pbr during flow rate control.
If it is larger, the control signal Qp based on the pressure is selected. If not, the control signal Qc based on the flow rate is selected. On the other hand, if the direction command Dir is meter-out, the pressure is higher if the outlet pressure Pb is larger than the pressure command signal Pbr. The control signal Qp based on the flow rate is selected. Otherwise, the control signal Qc based on the flow rate is selected, and the selected control signal Qc or Qp is output as the control signal Xq to the control calculation circuit 23 (step S15). Selected control signal Q
The valve opening is determined based on c or the control signal Qp, and the control valve 1 is driven by the valve drive circuit 24 to a predetermined valve opening.

As described above, by repeating steps S1 to S15, one control valve 1 controls the flow rate control and the pressure control in accordance with a preset condition in accordance with a direction command Dir given from a direction command means (not shown). This can be performed alternately, and a hydraulic circuit that requires control of both the flow rate and the pressure can be simply configured, so that both the manufacturing and maintenance costs can be reduced.

FIG. 4 is a graph showing the relationship between the pressure and the flow rate when an actuator (not shown) is activated by the above control in the meter-in hydraulic circuit shown in FIG.

Now, in order to start the actuator from the stopped state, the flow command signal Qr is larger than the flow Q passing through the control valve 1 because the amount of bleed from the outlet port 10B to the tank 12 is very small. Therefore, the control signal Qp based on the pressure is selected as the control signal Xq from steps S8 and S9 in the flowchart of FIG.
The driving of the actuator is started by the pressure control.

Here, the pressure command signal Pbr is given as a command for reducing the pressure, and the control valve 1 is opened by the control signal Qp based on the pressure command signal Pbr, and the actuator is displaced. At this time, the flow rate Q passing through the control valve 1
Is represented by the following equation.

[0038]

(Equation 2)

After a time t ₁ from the drive of the actuator, the valve passing flow rate Q tends to exceed the flow rate command signal Qr. At this time, since the outlet pressure Pb has not increased to the pressure corresponding to the pressure command signal Pbr, the control signal Qc based on the flow rate is selected as the control signal Xq from steps S8, S10, and S11 in the flowchart of FIG. The drive of the actuator is started by the control, and the flow rate Q is controlled to be equal to the flow rate command signal Qr.

As described above, during the pressure control, the pressure command signal P
The smaller of the flow rate Q passing through the control valve 1 and the flow rate of the flow rate command signal Qr indicated by br is selected, and the pressure control is automatically switched to the flow rate control.

FIG. 5 shows the valve unit 10 connected to a meter-out hydraulic circuit.
Is connected to an actuator (not shown), the tank 12 is connected to the inlet port 10A, and the other configuration is the same as that of the first embodiment.

In this case, the inlet pressure Pb is equal to the pressure command signal Pbr
If it is larger, the control signal Qp based on the pressure is selected from steps S12 and S13 in the flowchart of FIG. 3 to perform pressure control, and the valve opening of the control valve 1 is increased to increase the flow rate Q, thereby increasing the inlet pressure Pb. Reduce the pressure.

On the other hand, when the pressure command signal Pbr becomes larger than the inlet pressure Pb, the control signal Qc based on the flow rate is selected from steps S12 and S14 in the flowchart of FIG. You can.

[0044]

As described above, according to the present invention, based on the meter-in or meter-out direction command of the direction command means, the selection means is set to meter-in, and the flow rate command signal Qr is set to the calculated flow rate during pressure control. If the outlet pressure Pb is larger than the pressure command signal Pbr during the flow control, the control signal Qp based on the pressure is selected. If not, the control signal Qc based on the flow rate is selected.
If the inlet pressure Pb is larger than the pressure command signal Pbr in the comparison result when the meter is out, the control signal Qp based on the pressure is selected, and if not, the control signal Qc based on the flow rate is selected and output to the valve driving means. Therefore, it is possible to automatically switch between flow control and pressure control with one valve according to the flow direction,
A hydraulic circuit that requires control of both pressures can be simply configured with one valve, and both manufacturing and maintenance costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart showing the contents of control.

FIG. 4 is a graph showing the contents of control.

FIG. 5 is a block diagram showing another embodiment.

FIG. 6 is a block diagram showing a conventional example.

FIG. 7 is a block diagram showing a conventional example.

FIG. 8 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control valve 2 Displacement sensor 3 Pressure sensor 4 Pressure sensor 21 Flow rate operation circuit 22 Command selection control circuit 23 Control operation circuit 24 Valve drive circuit 51 Valve 52 Openness detection means 53, 54 Pressure detection means 55 Flow rate calculation means 56, 57 Control Signal calculation means 58 Direction command means 59 Selection means 60 Driving means 61, 62 Comparison means

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) F16K 31/06-31/11 F15B 11/00 F15B 13/00 G05D 16/00 G05D 7/00

Claims (1)

(57) [Claims] A valve whose opening degree changes according to a signal;
Means for detecting the opening of the valve, means for detecting the pressures Pa and Pb at the inlet and outlet of the valve, means for calculating the flow rate Q from the pressure difference between the detected pressures and the detected opening of the valve, The calculation result of the flow rate Q and the flow rate command signal QR
Means for calculating the control signal Qc based on the flow rate from the above, means for calculating the control signal Qp based on the pressure from the detected pressure Pb at the outlet and the pressure command signal Pbr, and comparing the flow rate command signal Qr with the calculated flow rate Q Means for comparing the pressure command signal Pbr with the outlet pressure Pb; means for instructing the flow direction of one of the meter-in and meter-out of the valve; and If the comparison result indicates that the flow rate command signal Qr is greater than the calculated flow rate Q or the outlet pressure Pb is greater than the pressure command signal Pbr, the control signal Qp based on the pressure is selected, otherwise the control signal Qc based on the flow rate is selected. On the other hand, when the direction command is meter-out, if the outlet pressure Pb is larger than the pressure command signal Pbr in the comparison result, the control signal Qp based on the pressure is output. A proportional electromagnetic control valve comprising: means for selecting a control signal Qc based on the flow rate; and means for driving the valve based on the selected control signal.