JPH01161701A - Solenoid with position sensor - Google Patents

Abstract

PURPOSE:To reduce the number of components, to decrease its cost, to diminish its shape, and to facilitate its manufacture by winding coils for a differential transformer for detecting the position of a movable plunger on the same bobbin as that of a coil for driving a movable plunger. CONSTITUTION:In a solenoid operating in a linear direction by electromagnetic force, coils 10a, 10b, 11 for a differential transformer for detecting the position of a plunger 5 are wound on the same bobbin 2 as that of a coil 3 for driving a movable plunger. For example, the exciting coil 11 and a pair of the detecting coils 10a, 10b are provided inside the coil 3 thereby to constitute a differential transformer for detecting the position of the movable plunger. When a signal having several kHz of AC is input to the coil 11, an induced AC flows to the coils 10a, 10b. When the plunger 5 is moved at this time, the inductances L of the coils 10a, 10b are altered. Thus, a voltage between the terminals of the coils 10a, 10b is varied. When the difference of the voltages is taken, a signal different depending upon the amplitude according to the position of the plunger 5 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a linear drive device capable of position control.

(Prior art) Conventionally, as a linear drive device capable of controlling one position, one
A solenoid with a position sensor is known which has a configuration in which a differential transformer is attached to the solenoid body as shown in the figure. Its structure is such that a movable plunger driving coil 3 (hereinafter referred to as driving coil), which is a bobbin 2 wound with copper wire, and a yoke 4 are fitted inside a casing 1 made of a magnetic material.

Further, a movable plunger 5 made of a magnetic material is provided inside the drive coil 3 and mounted on a shaft 6 made of a non-magnetic material. A stopper 7 is provided to prevent the plunger from falling. A differential transformer 8 is attached to the end of the yoke 4, and a movable core 9 within the differential transformer 8 is attached to the tip of the shaft 6. - When a current is applied to the drive coil 3, a magnetic circuit as shown by the dashed line arrow in FIG. 7 is formed, and the movable plunger 5
is attracted to the yoke 4 and moves.

At this time, since the movable iron core 9 provided on the shaft 6 also moves together, the output voltage from the differential transformer 8 increases proportionally to the displacement of the movable plunger 5, so that the position of the movable plunger 5 can be known. Therefore, positioning becomes possible by using a position control circuit.

As shown in FIG. 8, the differential transformer 8 consists of an excitation coil 8a and a pair of detection coils 8b and 8c.
When an alternating current signal of several KHz is constantly excited, an induced voltage is generated on the detection coils 8b and 8c. When the movable core 9 enters the detection coils 8b and 8c, the inductance L of the detection coils 8b and 8c changes, so by taking the relative difference between the detection coils 8b and 8c, the movable core 9
It is possible to detect minute displacements of

(Problems to be Solved by the Invention) However, since the differential transformer 8 is attached to the solenoid body, there are problems in that the number of parts increases, the shape becomes large, and the price becomes high.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a solenoid that operates in a linear direction by electromagnetic force. A coil for a dynamic transformer is wound around the coil.

(Function) According to the present invention, the displacement of the movable plunger can be directly detected within the bobbin by winding the movable plunger drive coil and the movable plunger position detection differential transformer coil around the same bobbin.

(Embodiment) FIG. 1 is a diagram illustrating an embodiment of the present invention, in which 1 is a housing;
2 is a bobbin, 3 is a drive coil, 4 is a yoke, 5 is a movable plunger, 6 is a shaft, 7 is a stopper, 11 is an excitation coil for a differential transformer for detecting the position of the movable plunger (hereinafter referred to as excitation coil), 10a, 10b is a detection coil (hereinafter referred to as detection coil) of a differential transformer for detecting the position of the movable plunger. The operation of the plunger 5 is the same as that described in the conventional example, but as shown in the cross-sectional perspective view of the bobbin in FIG.
1 and a pair of detection coils 10a.

10b constitutes a differential transformer for detecting the position of the movable plunger.

When current is applied to the drive coil 3, a magnetic circuit is formed as in the conventional example, and the plunger 5 is attracted to the yoke 4 and moves. At this time, as the plunger 5 moves, the inductance L of the pair of detection coils 10a and 10b changes. When an AC signal of several KHz is input to the excitation coil 11, it is induced into the detection coils 10a and 10b and the excitation coil 1
AC flows as in 1. As mentioned above, plunger 5
When the fob is moved, the inductance L of the detection coils 10a and 10b changes, so that the voltage between the terminals of each coil of the detection coils Oa and Fob also changes. Therefore, detection coil 1
By taking the difference between 0a and 10b, it is possible to obtain signals with different amplitudes depending on the position of the plunger 5. This will be described in more detail using FIGS. 3(a) to 3(C).

3(a) to 3(c) show how the voltage between the terminals of the excitation coil 11 and the detection coils 10a, 10b changes as the plunger 5 moves.

As shown in FIG. 3(a), when the plunger 5 comes to a position slightly inside one of the detection coils 10b, the voltage across both ends detected by each detection coil 10a, 10b is (a
)'become that way. As shown in FIG. 3(b), when the plunger 5 is located between the detection coils, the detection coil 10
If a and 10b are exactly the same, each detection coil 10
The voltage at both ends detected from a and 10b is as shown in (b)'. As shown in FIG. 3(c), when the position of the plunger 5 is opposite to that in FIG. 3(a), each detection coil 10
The voltage across the terminals a and 10b is as shown in (C)'.

Then, if we take the difference between the voltages at both ends, (a)'',
The outputs of the detection coils 10a and 10b due to the movement of the plunger 5, that is, the position of the plunger 5 can be determined as shown in FIGS.

Another embodiment will be explained with reference to FIG. As shown in FIG. 4, which is a cross-sectional perspective view of the bobbin 2, a detection coil 10a is provided below the movable plunger drive coil 3.

10b is provided and the excitation signal is sent to the movable plunger drive coil at the same time as the drive signal, so that the same function as in the previous embodiment is achieved. The excitation signal is relative to the drive signal.

The frequency is sufficiently high.

In this case, the excitation signal source and the drive signal source are connected to the drive coil 3 through an electric circuit that does not interfere with each other.

FIG. 5 illustrates this embodiment. As shown in FIG. 5, the signals from the movable plunger drive power source 13 and the excitation signal oscillator 14 are added and sent to the drive coil 3. At this time, a choke coil 12 is connected in front of the movable plunger drive power source 13 and a capacitor 15 is connected in front of the excitation signal oscillator 14 so as not to interfere with each other.

(Effects of the Invention) As explained in detail above, according to the present invention, in a solenoid that operates in a linear direction by electromagnetic force, a differential transformer for detecting the position of the plunger is wound around the same bobbin as the bobbin of the movable plunger drive coil. This has the advantage of reducing the number of parts, making it cheaper, and making the shape more compact.Furthermore, winding the drive coil and the differential transformer coil around the bobbin can be done in the same process, making it easy to manufacture. .

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view of the present invention, FIG. 2 is a sectional perspective view of the bobbin, and FIG. 3 shows the output of the detection coil depending on the position of the plunger. In the figure, (
a) to (C)′ are the voltages across the position detection coil, (a)”
〜(C)'' is the difference in voltage between both ends. FIG. 4 shows the other embodiment of the present invention. FIG. 5 is a sectional view of the conventional example, FIG. 6 is a magnetic circuit configuration diagram, and FIG. The figure is a cross-sectional view of the configuration of a differential transformer. 1... Housing 2... Bobbin 3... Drive coil 4... Yoke 5... ...Movable plunger 6...Shaft 7.
...Stopper 8...Differential transformer 9...Movable core 10a, 10b...Position detection coil 11...
... Excitation coil 12 Old... Choke coil 13
......Movable plunger drive power supply 14...
Excitation signal oscillator patent applicant Copal Electronics Co., Ltd. Figure 1 Figure 2 Cleaning recess in the drawing Figure 3 61 82 B4CI
C2C4 Figure 4 Figure 5 Figure 6 Figure 8 Procedure amendment (method) July 2z, 1938

Claims (3)

[Claims] (1) A solenoid with a position sensor that operates in a linear direction by electromagnetic force, characterized in that a coil for a differential transformer for detecting the position of a plunger is wound around the same bobbin as a movable plunger drive coil. (2) The position sensor according to claim 1, wherein the differential transformer coil is excited by an alternating current at a frequency sufficiently higher than the highest frequency of the alternating current component included in the plunger driving current. With solenoid. (3) The solenoid with a position sensor according to claim 1, characterized in that the solenoid with a position sensor serves both as an excitation coil of the differential transformer and a coil for driving the movable plunger.