JPS6253928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a solenoid drive current control device used in solenoid valves, solenoid switches, and the like.

(Prior art) As a conventional solenoid drive current control device,
For example, a device as described in Japanese Patent Laid-Open No. 54-15165 is known.

In this conventional device, a microresistance is inserted in series with a solenoid, and the drive current flowing through the solenoid is controlled using this terminal voltage difference as a current feedback signal.

Further, as a conventional solenoid drive current control device, for example, a device as described in Japanese Patent Laid-Open No. 103708/1983 is known.

This conventional device includes a magnetic path changing member made of a ferromagnetic material that moves in and out of a magnetic air gap hole provided in a part of the magnetic path in conjunction with the movement of an armature. A magnetoelectric transducer is provided nearby, the magnetoelectric transducer detects the amount of leakage magnetic flux from the magnetic air gap hole, and the drive current flowing through the solenoid is controlled based on the detected amount of leakage magnetic flux.

(Problem to be solved by the invention) However, the former conventional device
15165), the drive current is controlled by the terminal voltage difference of a minute resistance, so it is unavoidable that it will be affected by the internal resistance due to the temperature rise of the solenoid and the voltage fluctuation of the drive voltage. ,
The holding current varied, and the solenoid disconnection time was not constant.

Also, the latter conventional device (Japanese Unexamined Patent Publication No. 103708/1983)
However, there were problems as described below.

Since leakage magnetic flux is detected instead of magnetic flux density, the direction of leakage magnetic flux changes depending on the positional relationship between the magnetic air gap hole and the magnetic path changing member.
Further, the amount of leakage magnetic flux cannot be accurately detected because the leakage magnetic flux is easily influenced by the presence of adjacent members made of magnetic material.

As mentioned above, since it is not possible to accurately detect the amount of leakage magnetic flux, stable solenoid operation control cannot be ensured.

Because the magnetoelectric conversion element (magnetic flux density sensor) is installed near the magnetic air gap hole that has the magnetic path changing member,
It requires the addition of a component called a magnetic path changing member, and since it is attached externally to the solenoid, it is susceptible to damage due to impact from a movable plunger or the like or interference with adjacent members.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems. A magnetic flux density sensor that is disposed perpendicular to the magnetic flux direction of the generated magnetic path and buried in the solenoid fixed side member to directly detect the magnetic flux density and output a magnetic flux signal; and the magnetic flux density sensor. When the magnetic flux reaches the required reference value to operate the solenoid,
The present invention is characterized by comprising a drive current control means for reducing the magnetic flux to a predetermined holding magnetic flux and controlling a solenoid drive current so that the holding magnetic flux is constant.

(Function) In the solenoid drive current control device of the present invention, the magnetic flux density is arranged perpendicular to the magnetic flux direction of the magnetic path generated by the excitation coil of the solenoid, and is embedded in the solenoid fixed side member. The magnetic flux density is directly detected by the sensor, and the drive current control means that inputs the magnetic flux signal from the magnetic flux density sensor controls the magnetic flux to a predetermined holding magnetic flux when the magnetic flux reaches the reference value required to operate the solenoid. The solenoid drive current is controlled so that the holding magnetic flux is reduced and held constant.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, a solenoid current control device for a solenoid valve will be taken as an example.

First, the configuration of the embodiment device will be explained with reference to FIGS. 1 to 6.

S is a solenoid part of a solenoid valve, and this solenoid part S includes an outer yoke 1, an exciting coil 2, a coil bobbin 3, an inner yoke 4, a non-magnetic body 5, a fixed plunger 6, a sleeve 7, and a movable plunger 8. It is composed of.

The magnetic path M is formed in a closed loop by the inner yoke 4, the fixed plunger 6, the sleeve 7, and the movable plunger 8, as shown in FIG.

Reference numeral 9 denotes a magnetoelectric conversion element as a magnetic flux density sensor, which is connected to the fixed side plunger 6 so as to be perpendicular to the magnetic flux direction of the magnetic path M, and also to the movable side plunger 8.
This device is buried in a position that can sufficiently withstand shocks from the magnetic field, and detects the magnetic flux density Bi of the magnetic path M and outputs a magnetic flux signal Bi.

In addition, the length l of the magnetic path M, the length δ of the air gap 10 between both plungers 6 and 8, the magnetic permeability μ of the magnetic path M, and the number of coil turns N, the magnetic flux passing through the inside of the magnetic path M and the magnetic flux of the air gap 10 are as follows. Assuming that there is no leakage of magnetic flux, the air gap 1
The magnetic flux density Bi at 0 is given by the following equation.

Bi=NI/{δ/μo+(l-δ)/μ} Therefore, as shown in Figure 4, the exciting current I of the exciting coil 2 and the magnetic flux density Bi of the magnetic path are in a proportional relationship, and the magnetic flux density This shows that Bi can be used as control data for the excitation current I (solenoid drive current).

Figure 5 shows typical magnetoelectric conversion elements.
This shows the relationship between the magnetic flux density and Hall voltage of a Ga-As-based Hall element, and the two are in a proportional relationship.
In addition, it is preferable because its temperature characteristics are stable.

11 is a signal amplification conversion circuit which amplifies the magnetic flux signal Bi from the magnetoelectric conversion element 9, and
It converts into a digital signal, and is composed of an amplifier 12 and an A/D converter 13.

Note that the signal amplification conversion circuit 11 outputs a signal P10 as a digital magnetic flux signal to a microprocessor 14, which will be described later.

14 is a microprocessor as a drive current control means, which inputs the signal P10 as the digital magnetic flux signal, and when the magnetic flux Bi reaches the reference value (maximum magnetic flux BM) necessary for operating the solenoid, the magnetic flux is controlled. Reduce the density Bi to a predetermined holding magnetic flux BH, and keep this holding magnetic flux BH constant.
An output signal P as an ON/OFF signal is sent from the output terminal to the drive transistor 16 of the power supply circuit 15, which will be described later.
It outputs 20, CPU, RAM, ROM,
It includes an I/O port, and a control program shown in the flowchart of FIG. 7 is prewritten in the ROM.

Reference numeral 15 denotes a power supply circuit which inputs the output signal P20 from the microprocessor 14 and applies a solenoid drive current from the power supply to the excitation coil 2.
This is a circuit that energizes Ci in accordance with an output signal P20, and when the output signal P20 is ON, a base current flows to the base side of the drive transistor 16, and a solenoid drive current Ci flows to the excitation coil 2.

Note that the power supply circuit 15 includes the drive transistor 1
6, a flywheel diode 17 for absorbing coil surge, a transistor protection capacitor 18, and a transistor protection Zener diode 19.

Reference numeral 20 denotes a power switch that applies voltage from a power source 21 to the microprocessor 14 as a solenoid command signal NF.

Note that 22 in the figure is a wiring port for an exciting coil, and 23 is a wiring port for a magnetoelectric conversion element.

Next, the operation will be explained with reference to FIGS. 7 to 9.
First, in judgment 201 of the microprocessor 14, it is determined whether the solenoid command signal NF is turned ON (FIG. 8, c-step).

If it is ON, the process proceeds to process 202, where the output signal P20 of the microprocessor 14 is turned on, and the process further proceeds to process 203.

In this process 203, the solenoid command signal NF
Magnetic flux density increases over time after turning on
Bi is read by the magnetic flux signal Bi from the magnetoelectric transducer 9 (FIG. 8c-step).

The magnetic flux signal actually input to the microprocessor 14 is an input signal P10 obtained by amplifying and digitally converting the magnetic flux signal Bi by the amplification conversion circuit 11.

Next, a decision 204 determines whether the magnetic flux signal Bi is the maximum magnetic flux signal required to actuate the solenoid.
Check if BM has been reached, magnetic flux signal Bi
If the magnetic flux signal BM has reached the maximum magnetic flux signal BM, it is determined that the solenoid has finished driving, and the microprocessor 14
The output signal P20 is turned off in step 205 (FIG. 8 c-step).

Then, in process 206, the magnetic flux signal Bi after reaching the maximum magnetic flux signal BM is read (Fig. 8 c-
step), and in judgment 207, the magnetic flux signal Bi is a holding magnetic flux signal necessary to maintain the movable plunger 8 in its current state.
Determine whether it is greater than or equal to BH.

Then, when the magnetic flux signal Bi falls to the level of the retained magnetic flux signal BH, the process proceeds to the ON/OFF control section 208,
If the magnetic flux signal Bi is larger than the retained magnetic flux signal BH, the process returns to step 206 and continues reading the magnetic flux signal Bi again.

Then, when the magnetic flux signal Bi≦the holding magnetic velocity signal BH, the ON/OFFF control unit 208 controls the solenoid.
Start ON/OFF control.

In the example, the ON time of the solenoid is set to be constant t1, and the length of the OFF time is controlled to control the magnetic flux signal.
Bi is set to the level of the holding magnetic flux signal BH (see Figure 9).

The ON/OFF control will be explained below with reference to FIG. 7. In process 209, the magnetic flux signal Bi is the retained magnetic flux signal
Microprocessor 1 has dropped to BH.
The output signal P20 of the microprocessor 14 is turned ON to increase the magnetic flux signal Bi.The timer unit 210 manages the ON time of the output signal P20 of the microprocessor 14 to maintain the t1ON state for a certain period of time. Turn off the output signal P20.

Further, in process 212, as in process 206, the magnetic flux signal Bi continues to be read until the magnetic flux signal Bi falls to the level of the retained magnetic flux signal BH, and in judgment 213 it is determined that the magnetic flux signal Bi has decreased to the level of the retained magnetic flux signal BH. Then, the process proceeds to decision 214, where it is determined whether the solenoid command signal NF shown in FIG. 8A is ON, and if it is OFF, this routine ends.

Also, in judgment 214, the solenoid command signal NF is
If it is in the ON state, the process returns to step 209 and the output signal P20 of the microprocessor 14 is turned ON.

Incidentally, in the judgment 201, if the solenoid command signal NF is not ON, the process proceeds to step 215, where the output signal P20 is turned OFF, and this routine ends.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

(Effects of the Invention) As explained above, the solenoid drive current control device of the present invention provides the following effects.

Since the magnetic flux density is directly detected by a magnetic flux density sensor arranged perpendicular to the magnetic flux direction, magnetic flux density information can be obtained with extremely high detection accuracy without being affected by external disturbances. Disturbances include the influence of internal resistance due to temperature rise of the solenoid, such as drive current control from the solenoid power supply side, the influence of voltage fluctuation of the drive voltage, and the position that changes the direction of leakage magnetic flux, such as when detecting leakage magnetic flux. There are effects such as the influence of relationships and the presence of adjacent magnetic materials that change the amount of leakage magnetic flux.

Since the accurate magnetic flux density information obtained by the effect of the above is used as feedback information to determine the reference value, it is possible to perform stable solenoid operation control, and reduce power consumption by reducing the drive current to the holding current. The reduction effect can be achieved effectively.

Since the magnetic flux density sensor is embedded in the solenoid fixed side member, there is no increase in the number of parts, and the magnetic flux density sensor is protected from damage due to impact from the movable plunger or interference with adjacent members.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a solenoid part of a solenoid valve to which a solenoid drive current control device according to an embodiment of the present invention is applied, FIG. 2 is a sectional view showing a fixed side plunger of the solenoid part, and FIG. 3 is a sectional view showing the fixed side of the solenoid part. A side view of the plunger, FIG. 4 is a relationship diagram between exciting current and air gap magnetic flux density, FIG. 5 is a relationship diagram between air gap magnetic flux density and Hall voltage, and FIG. 6 is an overall diagram showing the control device of the embodiment. Fig. 7 is an operation flowchart in the microprocessor of the embodiment device, Fig. 8 A, B, and C are comparison diagrams of solenoid command signals, output signals, and magnetic flux signals, and Fig. 9 A, B are holding magnetic flux signals. FIG. S... Solenoid part, 2... Excitation coil, M... Magnetic path, Bi... Magnetic flux density, Bi... Magnetic flux signal, 9... Magnetoelectric conversion element (magnetic flux density sensor), 14... Microprocessor (drive current control means), Ci... Solenoid drive current.

Claims (1)

[Claims] 1. A magnetic flux density sensor that is disposed perpendicular to the magnetic flux direction of the magnetic path generated by the excitation coil of the solenoid and embedded in the solenoid fixed side member to directly detect the magnetic flux density and output a magnetic flux signal. Then, the magnetic flux signal from the magnetic flux density sensor is input, and when the magnetic flux reaches the reference value required to operate the solenoid, the magnetic flux is reduced to a predetermined holding magnetic flux, and this holding magnetic flux is kept constant. A solenoid drive current control device comprising: drive current control means for controlling a solenoid drive current.