JP3312960B2 - 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. 9, 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 operation circuit 96 controls the valve opening Xr so that the flow Q becomes equal to the flow command Qr. 97 and the flow control valve 9
Numeral 1 is to drive a solenoid (not shown) 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 Qr, and decreases the valve opening X when the flow rate Q is larger than the flow rate command 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. If the outlet pressure Pb is smaller than the pressure command Pbr, the valve opening X is increased.
When the outlet pressure Pb is larger than the pressure command Pbr, the valve opening X
Decrease.

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]

Means for Solving the Problems The first aspect of the present invention is shown in FIG.
As shown in the figure, the valve 51 whose opening degree changes according to the signal
A bleed valve 61 for releasing a part of the pressure from the outlet side of the valve 51, and a means 5 for detecting an opening X of the valve 51.
2, means 53 and 54 for detecting the pressures Pa and Pb at the inlet and outlet of the valve 51, respectively; means 55 for calculating the flow rate Q from the pressure difference between the detected pressures and the detected opening X of the valve 51; The calculation result of the flow rate Q and the flow rate command signal QR
Means for calculating the valve opening degree Xq based on the flow rate from
6 and means 57 for calculating the valve opening Xp based on the pressure from the detected pressure Pb on the outlet side and the pressure command signal Pbr.
Means 58 for judging the flow direction of meter-in and meter-out from the pressure difference between the detected pressures, and when the judgment result is meter-in, the opening degree Xp based on the pressure is determined.
And one of the calculation results of the valve opening Xq based on the flow rate is determined to be smaller. When the determination result is meter-out, the opening degree Xp based on the pressure and the valve opening degree Xq based on the flow rate are determined.
Means 59 for selecting one of the larger calculation results, means 60 for driving the valve 51 based on the selected calculation result, and opening of the bleed valve 61 when the direction determination result is meter-in. And a driving means 62 for causing a valve.

Further, as shown in FIG. 2, the invention according to claim 2 comprises a correction table 63 in which a coefficient for correcting the valve opening degree Xq based on the flow rate in accordance with the result of the determination of the direction is set in advance. And a correction table 64 in which a coefficient for correcting the valve opening Xp based on the direction according to the determination result of the direction is set in advance, and the valve opening calculating means 56 based on the flow rate and the valve opening calculating means 57 based on the pressure are provided. The calculation results of the valve openings Xq and Xp are corrected based on the correction tables 63 and 64, respectively.

[0009]

Therefore, the invention of claim 1 is based on FIG.
The direction determining means 58 automatically determines meter-in or meter-out from the difference between the pressures Pa and Pb at the inlet and outlet of the valve 51, and the opening calculating means 56 determines the flow rate Q of the flow rate calculating means 55 and the flow rate command signal Qr. And the opening degree calculating means 57 calculates the valve opening degree Xq based on the flow rate from the outlet pressure Pb.
From the pressure command signal Pbr and the valve opening Xp based on the pressure
Is calculated. The selecting means 59 determines the smaller one of the calculation results of the opening degree Xp based on the pressure and the opening degree Xq based on the flow rate when the determination result of the direction determining means 58 is meter-in, and the pressure when the determination result is meter-out. The valve 51 is automatically operated according to the direction of flow and the valve openings Xq and Xp in order to select the larger one of the calculation results of the opening Xp based on the flow rate and the opening Xq based on the flow rate and output the result to the driving means 60. It is possible to switch between flow control and pressure control at
When the determination result is meter-in, the bleed valve 61 is automatically opened and a part of the pressure is released from the outlet side of the valve 51, so that the meter-in pressure control can be performed.

According to a second aspect of the present invention, as shown in FIG. 2, the valve openings Xq and Xp are respectively determined based on the correction table 63 and the correction table 64 in accordance with the result of the direction determining means 58. The calculation results are corrected by the calculation means 56 and 57, and the calculation results of the valve opening degrees Xq and Xp are corrected according to the characteristics of the valve 51.

[0011]

FIG. 3 shows an embodiment of the present invention.

In FIG. 3, a valve unit 10 constituting a proportional electromagnetic control valve has an inlet port 10A selectively connected to a pump 11 or a tank 12 via a directional control valve 13, while an outlet port 10B has Hydraulic cylinder 14
Is connected.

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).

A solenoid valve 5 as a bleed valve is interposed between the control valve 1 and the outlet port 10B and between a tank port 10C connected to the tank 12 and a throttle 6 downstream of the solenoid valve 5. Is provided.

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

The pressure sensors 3, 4 and the displacement sensor 2
Is input to a controller to be described later that drives the control valve 1 based on the flow rate and the pressure. Hereinafter, each part of the controller housed in the valve unit 10 will be described in detail.

First, a direction determining circuit 24 for determining the direction of the flow of the flow rate Q from the differential pressure ΔP between the inlet pressure Pa and the outlet pressure Pb detected by the pressure sensors 3 and 4 is provided. Direction determination circuit 2
Numeral 4 is for determining the control direction of the valve unit 10 based on the differential pressure ΔP between the inlet pressure Pa and the outlet pressure Pb and outputting a determination signal Dir. When ΔP> 0, Dir = “meter-in” ΔP ≦ 0 At this time, the judgment signal Dir is output according to the logic of Dir = “meter out”. Here, ΔP = Pa−Pb.

Next, as a control system based on the flow rate, the detected pressures Pa and Pb of the pressure sensors 3 and 4 and the detected opening degree X of the displacement sensor 2 are used to calculate a flow rate Q of the hydraulic oil passing through the control valve 1. Input to the circuit 21.

Since the opening area corresponding to the opening degree of the control valve 1 is known, the flow rate calculation circuit 21 is provided with the relationship between the valve opening degree and the opening area as a function in advance. The flow rate Q is calculated from the differential pressure ΔP between Pa and the outlet pressure Pb by the following equation.

[0020]

(Equation 1)

The calculated flow rate Q is input to a flow rate control calculation circuit 22 for calculating a valve opening Xq based on the flow rate.
As one example, the flow control arithmetic circuit 22 obtains a valve opening degree Xq based on the flow rate by multiplying a difference between the flow rate Q and a flow rate command signal Qr input from a setting unit (not shown) by a predetermined constant Kq.

Here, the constant Kq is preset according to the characteristics of the control valve 1, and the constant Kq is corrected based on the flow direction, that is, the above-mentioned determination signal Dir. The correction coefficient of the constant Kq is preset in a parameter table 29 as a correction table, and corrects the constant Kq according to the determination signal Dir as follows.

When Dir = “meter-in” Kq = Kqi Dir = when “meter-out” Kq = Kqo The parameter table 29 is a constant in the flow rate calculation circuit 21 for calculating the flow rate Q in the above equation (1). The correction coefficient of C is also stored, and the constant C is set as follows according to the determination signal Dir in the same manner as the constant Kq.

When Dir = “meter-in” C = Ci When Dir = “meter-out” C = Co On the other hand, as a pressure-based control system, an output pressure Pb of the pressure sensor 4 and an input from setting means (not shown) are input. A pressure control arithmetic circuit 23 for calculating a valve opening Xp based on pressure from the pressure command signal Pbr is provided.

As an example, the pressure control calculation circuit 23 calculates the valve opening Xp based on the pressure by multiplying the difference between the outlet pressure Pb and the pressure command signal Pbr by a predetermined constant Kp.

Here, the constant Kp is set in advance according to the characteristics of the control valve 1, and the constant Kp is corrected based on the flow direction, that is, the above-mentioned determination signal Dir. The correction coefficient of the constant Kp is preset in a parameter table 29 as a correction table, and corrects the constant Kp according to the determination signal Dir as follows.

When Dir = “meter-in” Kp = Kpi When Dir = “meter-out” Kp = Kpo Although the flow rate control arithmetic circuit 22 and the pressure control arithmetic circuit 23 are configured by a multiplier as an example here, Of course, it may be composed of various compensators (PID, phase lead / lag etc.) based on the control theory.

The valve openings Xq and Xp and the determination signal Dir based on the sensor outputs thus obtained are input to a valve opening command determination circuit 25, respectively.

The valve opening command determining circuit 25 includes a direction determining circuit 2
When the judgment signal Dir from 4 is meter-in, the smaller one of the valve opening Xp based on pressure and the valve opening Xq based on flow rate is selected, and when the judgment signal Dir is meter-out, the valve opening based on pressure is selected. The larger of the degree Xp and the valve opening Xq based on the flow rate is selected, and the selected valve opening Xp or Xq is output as the valve opening command Xr.

Based on this valve opening command Xr, the valve opening control circuit 26 drives the valve of the control valve 1 to a predetermined opening based on the current valve opening X.

In synchronization with the control of the control valve 1, the control of the solenoid valve 5 as a bleed valve is also performed.
7 sends an opening signal of the solenoid valve 5 to the drive circuit 28 when the judgment signal Dir of the direction judging circuit 24 is "Meter-in" to open the solenoid valve 5 to open the outlet port 10B of the control valve 1.
The side communicates with the tank 12 to allow pressure control in the meter-in flow.

Next, control when the controller is constituted by a microcomputer will be described with reference to a flowchart shown in FIG.

The inlet pressure Pa and the outlet pressure Pb of the pressure sensors 3 and 4
Is read, and it is determined from this differential pressure ΔP whether it is meter-in or meter-out in the same manner as in the direction determination circuit 24 (step S1).

Based on the differential pressure ΔP and the detected opening X of the displacement sensor 2, the flow rate Q is calculated from the above equation (1) in the same manner as in the flow rate calculation circuit 21, and a flow rate command signal Qr from command means (not shown) is read. Then, the valve opening Xq based on the flow rate is calculated in the same manner as the flow control arithmetic circuit 22 (steps S2 to S4).

Next, the pressure command signal Pbr from the command means (not shown) is read, and then the pressure command signal Pbr and the outlet pressure P
By multiplying the difference from b by a predetermined constant Kp, the valve opening Xp based on the pressure is calculated (steps S5 to S6).

After calculating the valve opening Xq based on the flow rate and the valve Xp based on the pressure, a conditional branch is performed according to the result of the determination of the flow direction. If the determination result in S1 is meter-in, go to S8; if it is meter-out, go to S1.
Go to Step 2 (Step S7).

In the meter-in control, the valve opening Xq based on the flow rate is compared with the valve opening Xp based on the pressure, and the smaller one is substituted for the valve opening command Xr, and the solenoid valve 5 as a bleed valve is opened. The valve is turned on to discharge a part of the downstream side of the control valve 1 to the tank 12 via the orifice 6 (steps S8 to S11).

On the other hand, in the meter-out control, the valve opening Xq based on the flow rate is compared with the valve opening Xp based on the pressure, and the larger one is substituted into the valve opening command Xr, and the solenoid valve 5 as a bleed valve is activated. Close the valve (OFF) (Step S
12 to S15).

Finally, by outputting a valve opening command Xr to the control valve 1 and driving it to a predetermined valve opening, control based on the flow command signal Qr or the pressure command signal Pbr can be automatically determined and performed. Yes (step S16).

As described above, by repeating steps S1 to S16, the flow direction is automatically determined, and the flow control and the pressure control can be alternately performed by one control valve 1 in accordance with preset conditions. This makes it possible to simply configure a hydraulic circuit that requires control of both the flow rate and the pressure, thereby reducing both manufacturing and maintenance costs.

FIG. 5 shows another embodiment in which the valve unit 10 of the first embodiment is applied to a meter-in hydraulic circuit employed in an injection molding machine or the like. While connected to the inlet port 10A, the outlet port 10B is connected to the oil chamber on the extension side of the hydraulic cylinder 14 via a pressure reducing valve 16 as a safety valve.

In this hydraulic circuit, the hydraulic cylinder 1
4 is extended until it comes into contact with the obstacle 7 by the flow rate control, and then a pressure-holding process of maintaining a predetermined pressure by the pressure control is performed. The state of the control at this time will be described with reference to the graph of FIG. explain.

[0043] Step The obstacle 7 to abut time T ₁ in the flowchart of FIG. 4 of the first embodiment S
8, the valve opening Xq based on the flow rate is selected from S9, and the hydraulic cylinder 14 is controlled by the speed to set the valve opening Xq based on the flow rate command signal Qr as the valve opening command Xr.

The flow rate Q after the time T _{1 at} which the obstacle 7 comes into contact with the obstacle 7.
Decreases, the valve opening Xq based on the flow rate command signal Qr increases, while the valve opening Xp based on the pressure command signal Pbr decreases as the outlet pressure Pb increases.

After the time T ₂ , the valve opening Xp based on the pressure becomes smaller than the valve opening Xq based on the flow rate, and step S in the flowchart of FIG. 4 of the first embodiment is performed.
8. From S10, the valve opening Xp based on the pressure is selected as the valve opening command Xr, and the control can be automatically shifted to the control based on the pressure command signal Pbr.

FIG. 7 shows still another embodiment, in which the valve unit 10 of the first embodiment is applied to a bleed-off hydraulic circuit used for controlling a hydraulic elevator or the like.

The pump 11 is connected to an oil chamber on the extension side of a hydraulic cylinder 14 that supports the elevator 8, and is bleed to the tank 12 via the valve unit 10.
The speed of the elevator 8 is controlled by the valve unit 10 controlling the bleed amount. The valve unit 10 is set to a meter-out which connects the outlet port 10B to the pump 11 and the inlet port 10A to the tank 12.

The relief valve 16 disposed in parallel with the valve unit 10 prevents the pump 10 from being overloaded when the elevator 8 exceeds the allowable weight or is locked by an obstacle.

The state of control in this hydraulic circuit will be described with reference to the graph of FIG.

When the elevator 8 is stopped, the entire discharge amount of the pump 11 is bleed from the valve unit 10, and when the elevator 8 starts to rise, the flow rate command signal Qr
The hydraulic oil is supplied to the hydraulic cylinder 14 by decreasing the valve opening Xq based on the above.

At this time, since the load pressure Pb (the output of the pressure sensor 4 in the first embodiment) is smaller than the pressure command signal Pbr preset as the overload pressure, the valve opening Xp based on the pressure becomes zero. On the other hand, since the valve opening Xq based on the flow rate is larger than the valve opening Xp, the first
S12 and S1 in the flowchart of FIG.
3, the valve opening Xq based on the flow rate is selected as the valve opening command Xr, and the elevator 8 is controlled based on the speed.

[0052] During the rise, when the load pressure Pb, etc. engagement by the overload or obstruction of the elevator 8 as shown in FIG during the time T ₁ is greater than the overload pressure Pbr rises, the load pressure Pb In order to reduce the pressure, the valve opening Xp based on the pressure increases.

[0053] Then, since the valve opening Xp based on pressure is greater than the valve opening Xq based on the flow rate in the time T ₂ later, S12 in the flowchart of FIG. 4 of the first embodiment, S14 valve opening based on the pressure from the The degree Xp is selected as the valve opening command Xr, and the elevator 8 is controlled based on the load pressure.

[0054]

As described above, according to the present invention, the direction determining means automatically determines meter-in or meter-out from the difference between the inlet pressure Pa and the outlet pressure Pb of the valve, and the result of this determination is the meter-in or meter-out. The smaller of the calculation results of the opening degree Xp based on pressure and the opening degree Xq based on flow rate is the smaller of the calculation results of the opening degree Xp based on pressure and the opening degree Xq based on flow rate when the determination result is meter-out. Since the larger one is selected and output to the driving means, it is possible to automatically determine the flow direction and automatically switch between the flow control and the pressure control with one valve. The hydraulic circuit that requires control of the valve can be simply configured by one valve, thereby reducing both the manufacturing and maintenance costs, and using the bleed valve as a direction determining means. The automatic drive based on the fixed result eliminates the need for operation that accompanies a change in the direction of flow, and allows the valve to be interposed at any position in the hydraulic circuit, increasing design flexibility. Can be improved.

Further, it becomes possible to automatically perform correction according to the flow direction controlled by the valve, and it is possible to improve the accuracy of flow rate or pressure control according to the characteristics of the valve.

[Brief description of the drawings]

FIG. 1 is a claim correspondence diagram corresponding to the invention of claim 1;

FIG. 2 is a diagram corresponding to claims corresponding to the invention of claim 2;

FIG. 3 is a block diagram showing an embodiment of the present invention.

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

FIG. 5 is a block diagram showing another embodiment.

FIG. 6 is a graph showing the contents of control.

FIG. 7 is a block diagram showing still another embodiment.

FIG. 8 is a graph showing the contents of control.

FIG. 9 is a block diagram showing a conventional example.

FIG. 10 is a block diagram showing a conventional example.

FIG. 11 is a block diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 control valve 2 displacement sensor 3 pressure sensor 4 pressure sensor 5 solenoid valve 10 valve unit 12 tank 21 flow rate calculation circuit 22 flow rate control calculation circuit 23 pressure control calculation circuit 24 flow direction determination circuit 25 valve opening command determination circuit 26 valve opening Control circuit 27 Bleed determination circuit 28 Bleed valve drive circuit 29 Parameter table 30 Parameter table 51 Valve 52 Opening detecting means 53, 54 Pressure detecting means 55 Flow rate calculating means 56, 57 Valve opening calculating means 58 Direction determining means 59 Selecting means 60 Driving means 61 Bleed valve 62 Driving means 63 Correction table 64 Correction table

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16K 31/06-31/11 G05D 7/00 G05D 16/00 F15B 13/00-13/044 F15B 11 / 00

Claims (2)

(57) [Claims] A valve whose opening degree changes according to a signal;
A bleed valve that releases a part of the pressure from the outlet side of the valve, means for detecting the opening degree of the valve, means for detecting the pressures at the inlet and outlet of the valve, respectively, and a pressure difference between the detected pressure and the valve. Means for calculating the flow rate from the detected opening degree, means for calculating the opening degree of the valve based on the flow rate from the calculation result of the flow rate and the flow rate command signal, and pressure from the detected pressure and the pressure command signal on the outlet side. Means for calculating the opening of the valve based on the pressure, means for determining the flow direction of meter-in and meter-out from the pressure difference of the detected pressure, and the opening and flow based on the pressure when the result of this determination is meter-in The smaller one of the calculation results of the valve opening based on the above, and the larger one of the calculation results of the opening based on the pressure and the valve opening based on the flow rate when the determination result is meter-out. Means for selecting one, and means for driving the valve based on the selected arithmetic operation result,
A drive unit for opening the bleed valve when the result of the direction determination is meter-in. 2. A correction table in which a coefficient for correcting the valve opening based on the flow rate in accordance with the determination result in the direction is set in advance, and the valve opening based on the pressure is corrected in accordance with the determination result in the direction. A correction table in which coefficients are set in advance, wherein the valve opening calculation means based on the flow rate and the valve opening calculation means based on the pressure correct the calculation result of the valve opening based on the correction table, respectively. The proportional electromagnetic control valve according to claim 1.