JPH07105293B2 - Solenoid with position sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a linear drive device capable of position control.

(Prior Art) Conventionally, as a linear drive device capable of position control, for example,
2. Description of the Related Art A solenoid with a position sensor is known in which a differential transformer is attached to a solenoid body as shown in the figure. The structure is such that a movable plunger drive coil 3 (hereinafter referred to as a drive coil) having a bobbin 2 wound with a copper wire and a yoke 4 are fitted inside a housing 1 made of a magnetic material.

Further, a movable plunger 5 made of a magnetic material is provided inside the drive coil 3 by being attached to 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 iron core 9 in the differential transformer 8 is attached to the tip of the shaft 6.

When an electric current is passed through the driving coil 3, a magnetic circuit as shown by an alternate long and short dash line arrow in FIG.
Are attracted to the yoke 4 and move. At that time, since the movable iron core 9 provided on the shaft 6 moves together, the output voltage from the differential transformer appears in proportion to the displacement of the movable plunger 5, so that the position of the movable plunger 5 can be known. Therefore, positioning can be performed by using the position control circuit.

As shown in FIG. 8, the differential transformer 8 is composed of an exciting coil 8a and a pair of detecting coils 8b and 8c. If the exciting coil 8a is constantly excited with an AC signal of several KHz, the detecting coils 8b and 8c are Induction voltage is generated. Since the movable iron core 9 enters the detection coils 8b and 8c, the inductance L of the detection coils 8b and 8c respectively changes, and thus a slight displacement of the movable iron core 9 is detected by taking the relative difference between the detection coils 8b and 8c. It is possible.

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

(Means for Solving the Problems) In order to solve the above problems, the present invention relates to a solenoid that operates in a linear direction by an electromagnetic force, in which the movable plunger drive coil is mounted on the same bobbin as the movable plunger position detecting difference. It is a coil for a dynamic transformer.

(Operation) According to the present invention, the movable plunger driving coil and the movable plunger position detecting differential transformer coil can be wound around the same bobbin to detect the displacement of the movable plunger directly in the bobbin.

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

When a 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 to move. At this time, the inductance L of the pair of detection coils 10a and 10b changes due to the movement of the plunger 5.
When an AC signal of several KHz is input to the exciting coil 11, the alternating current flows in the same manner as the exciting coil 11 by being induced in the detection coils 10a and 10b. As described above, when the plunger 5 is moved, the inductance L of the detection coils 10a and 10b changes,
The terminal voltage of each coil of the detection coils 10a and 10b also changes. Therefore, if the difference between the detection coils 10a and 10b is taken, it is possible to obtain signals having different amplitudes depending on the position of the plunger 5. This will be described in more detail with reference to FIG. 3, A1, B1 and C1.

Fig. 3 A1, B1, C1 shows excitation coil 11 and detection coils 10a, 10b
It shows how the inter-terminal voltage of changes with the movement of the plunger 5.

As shown in FIG. 3A1, the plunger 5 has one detection coil.
When it comes to a position slightly inside 10b, the voltages across both ends detected by the respective detection coils 10a and 10b are shown in FIG.
It looks like A3. As shown in FIG. 3B1, when the plunger 5 is located in the middle of the detection coils, and when the detection coils 10a and 10b are exactly the same, the voltages across the detection coils 10a and 10b are B2 and B2 of FIG. 3, respectively. It becomes like B3. As shown in Fig. 3C1, the position of the plunger 5 is shown in Fig. 3A1.
In the opposite case, the voltages across both ends detected by the detection coils 10a and 10b are as shown in C2 and C3 of FIG. 3, respectively.

Then, if the difference between the voltages across the both ends is taken, 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 known as shown in A4, B4, and C4 in FIG. 3, respectively.

Further, FIG. 4 shows a sectional perspective view of the bobbin 2 for explaining another embodiment. By providing the detection coils 10a and 10b under the movable plunger drive coil 3 as shown in FIG. 4 and sending the excitation signal to the movable plunger drive coil at the same time as the drive signal,
The same function as in the above embodiment is performed. The excitation signal has a sufficiently high frequency with respect to the drive signal.

In this case, the excitation signal power 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 movable plunger drive power source 13 and the excitation signal oscillator 14
And the signals are sent to the drive coil 3. At this time, the choke coil 12 is connected in front of the movable plunger driving power source 13 and the 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 described in detail above, according to the present invention, in a solenoid that operates linearly by an electromagnetic force, a bobbin that is the same as the bobbin of the movable plunger drive coil is wound with a differential transformer for detecting the position of the plunger. Therefore, the number of parts can be reduced, the cost can be reduced, and the shape can be downsized. Furthermore, the drive coil and the coil of the differential transformer can be wound on the bobbin in the same process, which facilitates the manufacturing. .

[Brief description of drawings]

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 a bobbin, and FIGS.
1, C1 is a circuit diagram showing the position of the plunger, Fig. 3 A2, B2, C2
Are the position detection coils 10a in A1, B1 and C1 of Fig. 3, respectively.
3 is a waveform diagram showing the voltage across both ends, FIG. 3 A3, B3, C3 are waveform diagrams showing the voltage across the position detection coil 10b in FIG. 3 A1, B1, C1, respectively, and FIG. 3 A4, B4, C4 are respectively 3 Fig. A1, B1, C1
FIG. 4 is a waveform diagram showing a difference in voltage between both ends of the position detection coils 10a and 10b, FIGS. 4 to 5 are other embodiments according to the present invention, FIG. 5 is a sectional view of a conventional example, and FIG. FIG. 8 is a sectional view showing 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 iron core, 10a, 10b ... … Position detection coil 11… Excitation coil, 12… Choke coil 13… Movable plunger drive power supply 14… Excitation signal oscillator

Claims (3)

[Claims] 1. A solenoid with a position sensor, characterized in that, in a solenoid which operates linearly by an electromagnetic force, a coil for a differential transformer for detecting the position of the plunger is wound around the bobbin of a movable plunger drive coil. 2. The differential transformer coil is excited by an alternating current having a frequency sufficiently higher than the maximum frequency of the alternating current component contained in the plunger driving current. Solenoid with position sensor. 3. A solenoid with a position sensor according to claim 1, wherein the exciting coil of the differential transformer is also used as the movable plunger driving coil.