JPS6242217Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control valve in which the degree of opening of the valve can be appropriately selected by displacing the valve body by a desired dimension when moving the valve body in the control valve forward or backward.

In the case of such a control valve, when the plunger is moved by energizing the coil, if an external force is applied to the plunger or the valve body moved by the plunger, the plunger will deviate from the planned position. A detection member for detecting the displacement is connected, and the signal obtained from the detection member is fed back as a correction signal to the energization control circuit for the coil. The amount of energization is adjusted. Potentiometers and strain gauges are examples of the above-mentioned detection members, but potentiometers generally have a large form because they detect by moving a slider, and have the disadvantage of being limited in their placement location. In contrast, strain gauges perform detection by deforming themselves, so they are small and can be placed anywhere. The present invention relates to an electromagnetic proportional control valve using a strain gauge as the detection member.

When using a strain gauge as described above, in which one end of the strain gauge is connected to a case and the other end is connected to the plunger, the strain gauge deforms significantly each time the plunger moves, resulting in deformation of the strain gauge. The problem was that it was large and had a short lifespan.

Therefore, the present invention eliminates the above-mentioned problems and allows the plunger to be correctly moved to a planned position by detecting the displacement of the plunger using a strain gauge. Another object of the present invention is to provide an electromagnetic proportional control valve that can minimize deformation stress and have a long life.

The configuration of the present invention is that a case connected to the proportional control valve main body is provided with a coil and a plunger that moves forward and backward depending on whether or not the coil is energized, and the plunger is configured to control the proportional control valve. The plunger is connected to move forward and backward integrally with a spool that is provided in the valve body so as to be able to move forward and backward, and the plunger is applied with a biasing force in a direction opposite to the direction in which the plunger moves by energizing the coil. A balanced spring is attached to the plunger, and the plunger is further attached with a plunger position detection mechanism that detects the position of the plunger and outputs a position signal, while inputting a control signal. The input side of a control circuit that controls the amount of current to the coil in accordance with the control signal is connected to the control terminal, and the output side of the control circuit is connected to the coil, and the plunger position is connected to the control circuit. The detection mechanism is connected to the input side of a correction circuit that receives the position signal and outputs a correction signal, and the output side of the correction circuit is connected to the input side of the control circuit. The above plunger position detection mechanism is
A strain plate formed of an elastically deformable material and having one end fixed to the case; and a strain plate attached to the strain plate so as to be integrally deformable with the strain plate, and a signal corresponding to the degree of deformation of the strain plate as the position signal. The structure of the plunger position detection mechanism attached to the plunger is such that one end of the equalizing spring is connected to the plunger, and the other end is connected to the other end of the strain plate. This is a connected configuration. The effect is that when the plunger is displaced by energizing the coil through the control circuit, the displacement is transmitted to the strain plate via the equalizing spring, causing the strain plate to deform. In that case, most of the displacement of the plunger is absorbed by the balanced spring, and the amount of deformation of the strain plate is small. The strain gauge attached to the strain plate deforms together with the strain plate and outputs a signal corresponding to the amount of deformation. The signal is given to a control circuit through a correction circuit, and the amount of current applied to the coil is corrected.

The drawings showing the embodiments of the present application will be described below. In FIGS. 1 and 2, reference numeral 1 denotes a well-known proportional control valve main body, which is used, for example, as a flow rate control valve for liquid or gas. This main body 1
In the figure, 2 is a valve body, and 3 is a spool hole, each of which has a circular cross section. Reference numerals 4 and 5 denote output and input ports, respectively, and 6 a spool, which has a circular cross section and is wired within the spool hole 3 so as to be freely movable in the axial direction (horizontal direction in FIG. 1). 6a indicates a circulation groove formed in an annular shape on the outer peripheral surface. Although the above-mentioned valve body is for flow control, it may also be for pressure control. Next, in the solenoid 9 connected to the control valve main body 1 in a well-known structure, 10 is a solenoid case, which is made of a magnetic material (for example, iron) so as to function as a yoke. It is fixed to valve body 2. A coil 11 is constructed by winding a conducting wire 13 around a bobbin 12 made of a synthetic resin material, as is well known. 14
is a fixed iron core, and its tip 15 is formed to be thinner near the tip so that a suction force having a characteristic as shown in FIG. 5, which will be described later, will act on the plunger, which will be described later. 15a is an oil flow hole drilled in the fixed iron core;
16 indicates an O-ring for sealing. A cylindrical body 17 is connected to the fixed iron core 14 and is made of a non-magnetic material and has a cylindrical shape. A cylinder 18 is connected to the cylinder 17 and has a cylindrical shape. This cylindrical body 18 is made of a magnetic material and functions as a yoke. In addition, the fixed core 14, the cylindrical body 17, and the cylindrical body 1
The connecting portions between the tube 7 and the cylindrical body 18 are welded to form a watertight structure. Reference numeral 20 denotes a plunger, which is made of a magnetic material and is formed into a round rod shape.
8 so as to be freely movable in the axial direction (horizontal direction in FIG. 1) and rotatable around the axis. 22 is an interlocking pin, one end of which is connected to the plunger 20, the other end of which is connected to the spool 6,
The two are made to work together. 23 is a spacer, and the plunger 20 is attached to the end 18 of the cylindrical body 18.
It is made of a non-magnetic material to prevent it from being attracted to a. A fixing nut 24 is used to fix the case 10, the fixed core 14, the cylindrical bodies 17, 18, etc., and is screwed into a male thread 25 carved on the outer periphery of the tip of the cylindrical body 18. .

Next, in the plunger position detection mechanism 26,
Reference numeral 27 denotes a case, which is composed of a first case element 28 screwed onto the male screw 25 and a second case element 29 screwed onto a male screw 28a provided on the first case element 28. These elements 28,2
9 is made of a hard synthetic resin material in addition to metal. Reference numeral 30 denotes a strain plate, which is placed on a receiving portion 31 formed in a concave shape in the first case element 28, and is further held on the base 33 by a holding portion 32 in the second case element 29.
It is held in place by pressing down. This strain plate 30 is
It is formed using an elastically deformable material (for example, a spring material such as steel) that has good linearity between the magnitude of the load applied thereto and the degree of deformation when that load is applied. In this distortion plate 30, 34 indicates a flexible portion, and 35 indicates a spring receiving portion. 36a, 36
Reference numerals b, 36c, and 36d indicate strain gauges, which are respectively attached to the bending portion 34 so that they can be deformed integrally with the bending portion 34. Next, 37 is a connecting rod, one end of which is fixed to the plunger 20. Reference numeral 38 denotes a spring seat, which is also fixed to the other end of the connecting rod 37 with a set screw rod 39. Reference numeral 40 denotes a manual operation unit integrally formed with the spring seat 38. Reference numeral 41 designates a balanced spring interposed between the spring seat 38 and the spring receiving portion 35 of the distortion plate 30, which applies a biasing force to the spring seat 38 in a direction that prevents the plunger 20 from moving to the left in FIG. A compression coil spring is used to give

Next, FIG. 3 shows an electric circuit. In this figure, 42 is a power supply circuit, and strain gauge 36a
This is a circuit designed to supply power for operation to ~36d and the correction circuit 44, and a DC power supply circuit is used as an example. The correction circuit 44 is a strain gauge 36
It is constructed with a DC amplifier circuit 45 for amplifying the signals from a to 36d, and a resistor _R1 is interposed in its output circuit. Reference numeral 46 denotes a control circuit, which includes an operational amplifier 47, fixed resistors R ₂ and R ₃ , and a solenoid drive power amplification circuit 48 . Reference numeral 49 denotes a control terminal to which a control signal is input.

Next, FIG. 4 shows the power supply 42 and the strain gauges 36a to 36.
This shows the connection circuit with d. Each strain gauge 3
6a-36d are connected to the bridge as shown. Note that 50 indicates an output end, and this output end 5
0 is connected to the input terminal of the DC amplifier circuit 45.

Next, the operation of the above configuration will be explained. When a control signal is applied to the control terminal 49, the coil 11 is energized via the control circuit 46. As is well known, the amount of current supplied depends on the control signal applied to the control terminal 49. When the coil 11 is energized, a magnetic flux is generated in the coil 11, which attracts the plunger 20 to the left in FIG. The attraction force is shown as F ₁ to _{F 4} in FIG. 5 depending on whether the amount of current applied is large or small. When the plunger 20 is sucked as described above, the pin 22
The spool 6 is also moved in the same direction via the connecting rod 37 and the spring seat 38, and the equalizing spring 41 is compressed via the connecting rod 37 and the spring seat 38. The plunger 20 then stops at a point where its suction force and the repulsive force of the spring 41 (indicated by K in FIG. 5) are balanced. For example, in Figure 5,
Assuming that the attraction force corresponding to the above-mentioned amount of current is F ₃ , both forces are balanced at the point indicated by P, and the plunger 20 is moved to the first position by a distance indicated by X ₁ in FIG.
Move leftward from the position shown in the figure and stop.

On the other hand, the position of the plunger 20 after it has moved as described above is detected by the position detection mechanism 26. That is, plunger 2
When the balanced spring 41 is compressed according to a displacement of 0,
The strain plate 30 is slightly elastically deformed in response to the compressive force. That is, the flexible portion 34 is slightly bent. Then, each of the strain gauges 36a to 36d also bends together with the bending portion.
When each of the strain gauges 36a to 36d is bent in this way, their resistance values change depending on the degree of the bending, and a voltage signal corresponding to the change in resistance value appears at the output terminal 50. That is, a voltage signal corresponding to the displacement of the plunger 20 appears. FIG. 6 shows an example of the relationship between the displacement of the plunger 20 and the magnitude of the voltage signal at the output end 50.

This voltage signal is input to the correction circuit 44 as a position signal of the plunger 20. In the correction circuit 44, the voltage signal is amplified by a DC amplifier circuit 45, and the amplified voltage signal is outputted to a control circuit 46. In the above case, if the plunger 20 has moved to a position corresponding to the signal applied to the control terminal 49, the voltage signal from the correction circuit 44 will be a predetermined value, and the voltage signal from the control circuit 46 to the coil 11 will be a predetermined value. No correction can be made to the energization amount. However, if it has not moved to that position, the output signal of the correction circuit 44 that deviates from the predetermined value becomes a correction signal to the control circuit 46, and the amount of current flowing from the control circuit 46 to the coil 11 is corrected. Added.

For example, in the above case, if the plunger 20 moves only to the position shown as P' in FIG. 5, that is, the displacement is X', then as shown in FIG. The voltage value becomes V' and is larger than the voltage value V when the displacement is _X1 . Then, the control circuit 46 operates to increase the amount of current applied to the coil 11 in accordance with the correction signal outputted from the correction circuit 44 in accordance with the above voltage value V'. Then, the suction force increases and the moving distance of the plunger 20 increases. When the plunger 20 moves to the position indicated by P, the voltage value at the output end 50 becomes a predetermined value V. Therefore, the amount of current applied to the coil 11 is sufficient to hold the plunger 20 in this position, and the plunger 20 is held in that position.

By performing the above operations, ports 4 and 5 in the valve body 1 are brought into communication with an opening degree that accurately corresponds to the magnitude of the control signal, and the fluid flowing through these ports 4 and 5 is controlled. The flow rate has a value depending on the opening degree.

In the plunger position detection mechanism, the positional relationship between the spring seat 38 and the distortion plate 30 may be interchanged left and right in FIG. In that case, spring seat 3
It is preferable to use a tension spring as the equalizing spring 41 interposed between the strain plate 8 and the strain plate 30 so that the same biasing force as described above is applied to the plunger 20.

In addition to the manner of using the strain gauge shown in the above embodiments, well-known or well-known manners may be used.

As described above, in the present invention, when the solenoid coil 11 is energized via the control circuit 46 to displace the plunger 20 in the axial direction, the plunger 20 can be moved by specifying the amount of energization.
From the force relationship between the balance spring 41 and the plunger 2
It has the advantage that the 0 displacement position can be kept at an arbitrary position (a position corresponding to the amount of energization) in the middle position of the entire stroke. This has the advantage that the opening degree of the valve can be controlled.

Moreover, when the plunger 20 is stopped at the intermediate position of the entire stroke, the position of the plunger 20 is detected by the plunger position detection mechanism 26, and the position signal outputted from it is sent to the correction circuit 4.
4, and the amount of current applied to the coil 11 is corrected by the correction signal output from the correction circuit 44. Therefore, when the position of the plunger 20 in the axial direction deviates from the planned position, The amount of current applied to the coil 11 is corrected in accordance with the deviation dimension, so that the positional deviation can be corrected, and there is an advantage that the opening degree of the valve can be controlled with high precision.

Furthermore, in the present invention, to detect the position of the plunger 20, a plunger position detection mechanism 26 consisting of a strain plate 30 and a strain gauge attached to the strain plate 30 so as to be integrally deformable is used. This has the advantage that it can be used in locations with adverse conditions where there is a possibility that dust, water, oil, etc. may enter the plunger position detection mechanism 26. This has a wider range of uses than a potentiometer with a slider used as a plunger position detection mechanism, and also has the practical effect of being able to be used for a long time because it does not suffer mechanical wear like a slider. .

Furthermore, even if a strain gauge is used as a member for detecting the displacement of the plunger 20 in the plunger position detection mechanism 26 of the present invention, the other end of the equalizing spring 41 whose one end is connected to the plunger 20 is used. Since it is connected to the distortion plate 30,
When the displacement of the plunger 20 is detected by a strain gauge, even if the displacement of the plunger 20 is large, most of it is absorbed by the balancing spring 41, and only a slight deformation is exerted on the strain plate 30. Deformation can be kept small, deformation fatigue of the strain gauge can be kept to a minimum, and highly accurate position detection can be performed over a long life.

Furthermore, even if a spring is used to convert a large displacement of the plunger 20 into a small one, the equalizing spring 41, which is required individually in the proportional control valve, is also used as the spring for the above conversion. Therefore, even though this electromagnetic proportional control valve as a whole requires springs for the two purposes of conversion and balancing, one of them is omitted, and the product does not use the omitted springs. There is an effect that the price can be reduced by the required material cost, assembly cost, etc., and furthermore, there is also an effect that the storage space is not required, so that the overall shape can be made smaller.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application, and Fig. 1 is a longitudinal cross-sectional view, Fig. 2 is a partially cutaway perspective view of a strain plate and strain gauge, Fig. 3 is a circuit diagram, and Fig. 4 is a connection of the strain gauge. FIG. 5 is an operating characteristic diagram, and FIG. 6 is a graph showing the relationship between plunger displacement and output voltage. 1... Proportional control valve body, 11... Coil, 20
... Plunger, 26 ... Plunger position detection mechanism, 30 ... Strain plate, 36a to 36d ... Strain gauge, 38 ... Spring seat, 41 ... Balance spring.

Claims (1)

[Scope of utility model registration request] A case connected to the proportional control valve body is provided with a coil and a plunger that moves forward and backward depending on whether or not the coil is energized, and the plunger moves forward and backward within the proportional control valve body. The plunger is connected to move forward and backward in unison with a freely provided spool, and the plunger is configured to apply an urging force to the plunger in a direction opposite to the direction in which the plunger moves by energizing the coil. The plunger is further equipped with a plunger position detection mechanism that detects the position of the plunger and outputs a position signal, and a control terminal that inputs a control signal is attached to the plunger. is connected to the input side of a control circuit that controls the amount of current to the coil in accordance with the control signal, and the output side thereof is connected to the coil, and the plunger position detection mechanism is connected to the control circuit. In the electromagnetic proportional control valve, the input side of a correction circuit configured to receive a position signal and output a correction signal is connected, and the output side thereof is connected to the input side of the control circuit. , a strain plate formed of an elastically deformable material and having one end fixed to the case; and a strain plate attached to the strain plate so as to be integrally deformable with the strain plate, and transmitting a signal corresponding to the degree of deformation to the position signal. The structure of the plunger position detection mechanism attached to the plunger is such that one end of the balancing spring is connected to the plunger, and the other end is connected to the other end of the strain plate. An electromagnetic proportional control valve characterized by being connected to.