JPS624846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic drive device that is composed of an electromagnetic coil, a plunger, a yoke, etc., and generates an electromagnetic force in response to an electric signal. This invention relates to a means for eliminating hysteresis of electromagnetic force.

FIG. 1 shows a pressure control valve using a conventional electromagnetic drive device. In Figure 1, 1 is an electromagnetic coil, 2
is a plate spring 3a, 3 at both ends in the center of the electromagnetic coil 1.
The plunger 4 is a yoke supported by b, and the electromagnetic drive device 5 is constituted by the above. Reference numeral 6 denotes a pressure control section, the outer periphery of which is kept airtight by a valve seat 7, a valve body 8 provided opposite to the valve seat 7, and a valve body 9, and a diaphragm 10 and a valve body 8 that interlock with the valve body 8. It is composed of a spring 11 that acts in the direction of pressing the valve against the valve seat 7. Reference numeral 12 denotes an atmosphere communication hole that communicates the back pressure chamber A of the diaphragm 10 with the atmosphere. Here, the electromagnetic force generated by energizing the electromagnetic coil 1 is F _n , the primary pressure is P ₁ , the secondary pressure is P ₂ , the effective pressure receiving area of the diaphragm 10 is S _D , and the effective pressure of the valve body 8 is Letting the pressure-receiving area be S _V and considering the force balance, F _n +P ₁・S _V =P ₁・S _D +P ₂・S _V ...(1) Also, if S _D ≒S _V =S, ( Equation 1) is F _n = P ₂ · S ∴P ₂ = F _n /S ...(2), and regardless of the primary pressure P ₁ , the secondary pressure P ₂ (flow rate) is determined according to the electromagnetic force F _n . can be controlled.

A problem with a pressure control valve using this type of electromagnetic drive device is that the magnetic hysteresis of the members constituting the magnetic circuit, such as the plunger 2 and the yoke 4, directly leads to hysteresis in the control characteristics. This situation will be explained in detail using FIGS. 2 and 3. FIG. 2 shows the relationship between the displacement amount X of the valve body 8 and the electromagnetic force F _n of the electromagnetic drive device 5 using the coil current i as a parameter.

As can be seen from FIG. 2, even when the coil current i is constant, hysteresis occurs in the electromagnetic force F _n due to the amount of displacement, that is, the displacement of the plunger 2. Therefore, the points at which the electromagnetic force at each current value balances equation (2) P ₂ ·S are points a, b, and c, respectively, when the current increases, and points a′ and b when the current decreases. ′, c′. That is, in the relationship between the coil current and the secondary pressure _P2 shown in FIG. 3, hysteresis occurs when the current increases and when the current decreases. This magnetic hysteresis depends mainly on the materials of the members constituting the magnetic circuit, such as the plunger 2 and the yoke 4, and cannot be avoided. Therefore, in the conventional example, P ₂ is controlled based on the characteristics when the current decreases, but as shown in Fig. 3, the difference in ΔP ₂ in the current i _a becomes a minor loop characteristic. occurs,
Highly accurate pressure control cannot be expected. This becomes a problem particularly when controlling pressure (flow rate) with high precision, such as air-fuel ratio control.

Furthermore, as mentioned above, the conventional example has a well-known governor function that keeps the secondary pressure _P2 constant regardless of fluctuations in the primary pressure _P1 , but even when the current value is constant,
As a result, as shown in FIG. 4, two types of P and Q characteristics appear in the governor characteristics despite the same coil current, and even if each characteristic is good, the governor characteristics deteriorate by ΔP _2s , as shown in FIG. This point will be explained in detail using FIGS. 2 and 4. When the electromagnetic coil 1 is not energized, the primary pressure P ₁
is increased to P _1S , and then the electromagnetic coil 1 is energized to bring the secondary pressure P ₂ to the set pressure P _2S . The amount of displacement X at this time is point E in FIG. If P ₁ is increased to P _1n while keeping the coil energization amount constant, then from equation (2) F _n = P ₂・S
P ₂ increases, the valve body 8 is displaced upward, and X decreases to point F. After that, when P ₁ is decreased to O, P ₂ becomes O, so the valve body 8 is displaced to point M, which is the fully open point. After that, when P ₁ is increased again to P _1S , it becomes point G. In other words, only the hysteresis component of the electromagnetic force is F _n
The forces are balanced at the point where is large, and as a result, the fourth
The characteristics shown in Figure P appear.

The present invention has been made in view of the above-mentioned problems and aims to eliminate the hysteresis of electromagnetic force caused by the magnetic hysteresis of members constituting the magnetic circuit of an electromagnetic drive device.

In order to achieve this object, the present invention provides a displacement detection element that detects the displacement of a plunger or the like of an electromagnetic drive device, a displacement calculation circuit that receives the signal and calculates the displacement, and an electromagnetic force setting device. A correction circuit is provided which receives the signal from the displacement detection element and corrects the electromagnetic force so that it approaches the signal from the electromagnetic force setting device.

With this configuration, the hysteresis of the electromagnetic force at each displacement amount is corrected by the correction circuit so that it approaches the signal of the electromagnetic force setting device, so that the hysteresis of the electromagnetic force due to the magnetic hysteresis of the members constituting the magnetic circuit is equivalently corrected. can be resolved.

Hereinafter, one embodiment of the present invention will be described in detail using the drawings. Note that the same members in the figure as in FIG. 1 are designated by the same numbers and their explanations will be omitted.

FIG. 5 is a block diagram of a pressure control valve using an electromagnetic drive device showing an embodiment of the present invention. Reference numeral 13 denotes a plunger displacement detecting element provided on the upper part of the plunger 2, and is interlocked with the plunger 2. 14 is a displacement amount calculation circuit, and the displacement amount detection element 13
The signal is sent to the displacement amount detection circuit, and the slope detection circuit detects whether the displacement amount X is increasing or decreasing. Further, the turning point storage unit stores the turning point of the displacement amount X,
The amount of displacement from the turning point is sent to the correction circuit via the first comparator 15, and a correction electromagnetic force is calculated.
The correction signal calculated by the correction circuit is sent to the second comparator 16 through a limit circuit so that it does not exceed a predetermined correction value. On the other hand, the electromagnetic force setting device sends a signal that allows a predetermined electromagnetic force to be obtained by an external signal to the second comparator 16, and a corrected signal is sent to the electromagnetic coil 1. This situation will be explained in detail using FIG. 6. FIG. 6 is a characteristic diagram showing the relationship between the displacement amount X and the electromagnetic force F _n when the amount of current i ₁ from the electromagnetic force setting device is constant. Assuming that the plunger 1 is now displaced downward, F _n increases in proportion to X as shown by α. At this time, α is the value set by the electromagnetic force setting device, and no correction signal is added. After that, increase X to point A, and conversely
When F n decreases, F _n decreases along β. At this time, the slope detection circuit detects that the direction is decreasing, and at the same time, the displacement amount X _n of point A is stored in the turning point storage section, and the displacement amount Δx is detected with the displacement amount X _n as the origin. The signal is passed through a first comparator 15 to a correction circuit.

Here _{, the} electromagnetic force _{F n} is a function of _the electrical signal amount _i and the displacement _{amount D1} )
This signal is sent to the second comparator 16 as a correction signal i ₂ through the limit circuit. That is, an electric signal i ₃ is supplied to the electromagnetic coil 1 in a direction that reduces the electromagnetic force so that it approaches the signal α of the electromagnetic force setting device.

Also, when X is decreased to point B and then increased again, the slope detection circuit similarly detects that it is in the increasing direction, and at the same time stores the displacement amount X _B of point B in the turning point storage section _, Displacement Δ with origin as
x _U is detected, and the correction amount ΔF _U = _ko ·Δx _U is given as a correction signal. Therefore, as shown in the displacement vs. electromagnetic force characteristic in Figure 7, the hysteresis of the electromagnetic force F _n can be eliminated, and when it is taken as the characteristic of a pressure control valve, the hysteresis can be eliminated as shown in Figure 8. It is possible to obtain ideal coil current-secondary pressure characteristics, and realize a pressure control valve suitable even in cases where highly accurate control characteristics such as air-fuel ratio control are required.

Note that the coil current i ₁ in Figs. 7 and 8
indicates the current value before correction, that is, the current value corresponding to the external signal.

Moreover, unlike the conventional example, two types of characteristics do not appear in the governor characteristics, and there is an effect that governor characteristics with less fluctuation can be obtained.

As described above in detail, the electromagnetic drive device of the present invention is provided with a displacement detection element that detects the displacement of a plunger, etc., a displacement calculation circuit that receives the signal and calculates the displacement, and an electromagnetic force setting device. With,
A correction circuit is provided which calculates hysteresis of electromagnetic force caused by magnetic hysteresis of members constituting the magnetic circuit based on the signal from the displacement detection element, and corrects the electromagnetic force in a direction closer to the signal of the electromagnetic force setting device. Therefore, the hysteresis of the electromagnetic force caused by the magnetic hysteresis of the members constituting the magnetic circuit can be eliminated, and the conventional problems can be eliminated.

Further, since the correction signal is determined so as to approach the signal of the electromagnetic force setting device, the desired electromagnetic force can always be obtained even if there are dimensional variations in the members constituting the magnetic circuit, sliding resistance of the plunger, etc. In other words, it has the effect of reducing variations in characteristics.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a pressure control valve using a conventional electromagnetic drive device, Figure 2 is a characteristic diagram showing the relationship between the displacement amount and electromagnetic force, and Figure 3 is the relationship between the coil current and secondary pressure. FIG. 4 is a characteristic diagram of the same governor, FIG. 5 is a block diagram of a pressure control valve using an electromagnetic drive device showing one embodiment of the present invention, and FIGS. 6 and 7 are graphs of displacement and electromagnetic FIG. 8 is a characteristic diagram showing the relationship between force and FIG. 8 is a characteristic diagram showing the relationship between coil current and secondary pressure. 1... Electromagnetic coil, 2... Plunger, 4...
Yoke, 5... Electromagnetic drive device, 13... Displacement detection element, 14... Displacement calculation circuit, 15... First
Comparator.

Claims (1)

[Claims] 1. A magnetic circuit is configured by a plunger and a yoke, an electromagnetic coil is provided on the outer periphery of the plunger, and a displacement detection element of the plunger is provided,
and a displacement amount calculation circuit that receives a signal from the displacement amount detection element, and an electromagnetic force setting device that sets a necessary electromagnetic force using an external signal, and calculates hysteresis of the electromagnetic force based on the signal of the displacement amount calculation circuit; An electromagnetic drive device including a correction circuit that provides a correction signal so as to approximate the signal of the electromagnetic force setting device. 2. The displacement amount calculation circuit includes a displacement amount detection circuit, a slope detection circuit that detects the direction of displacement, a turning point storage section that stores the amount of displacement at the time when the direction of displacement changes, and the displacement amount detection circuit and the turning point. 2. The electromagnetic drive device according to claim 1, further comprising a first comparator that receives the signal from the storage section and provides the amount of displacement from the turning point to the correction circuit. 3. The electromagnetic drive device according to claim 1, further comprising a limit circuit that limits the signal from the correction circuit so that the correction signal does not exceed a predetermined value.