JPH08101006A - Variable capacitor - Google Patents

Abstract

PURPOSE: To provide a variable capacitor which can be controlled in capacitance even when the angle of rotation of its rotor exceeds 180 deg. despite of a small number of parts and a simple structure. CONSTITUTION: At least a pair of spiral springs 3 and 3, the base end sections 9 of which are fixed to pins 5 fixed to a casing 1 and energized ends 6 of which are fixed to a rotor 2, is wound so that the springs 3 and 3 can face each other with a clearance in between in the radial direction. When the springs 3 and 3 are provided in such a way, the clearance between the adjacent springs 3 and 3 in the radial direction decreases and the capacitance between the springs 3 and 3 increases by the decreased amount of the clearance when the rotor 2 rotates. When such a constitution is used, especially, the capacitance can be changed in accordance with the angle of rotation of the rotor 2 even when the angle exceeds 180 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable capacitor having a spring for returning rotation and a throttle sensor for detecting a rotation angle of a throttle valve using this variable capacitor.

[0002]

2. Description of the Related Art A conventional variable capacitor is constructed by alternately stacking a rotating flat plate electrode and a fixed flat plate electrode electrically insulated from each other. Changes the capacitance.

[0003]

The conventional plate electrode rotary type variable capacitor described above has the following problems. First, in order to secure the output accuracy of the electrostatic capacitance, it is necessary to accurately maintain the gaps between a large number of opposed rotating flat plate electrodes and fixed flat plate electrodes, which complicates the structure and assembly process. Therefore, it was necessary to secure the dimensional accuracy and rigidity of the parts.

Further, the change of the electrostatic capacitance due to the rotation of the rotating flat plate electrode is up to a rotation angle of 180 degrees, and it is a principle to realize a large change of the capacitance according to the rotation of 180 degrees or more. Up,
It was impossible. The present invention has been made in view of the above problems, and a variable capacitor capable of outputting an electrostatic capacitance even at a rotation angle of 180 degrees or more despite having a small number of parts and a simple structure, and a variable capacitor It is an object of the present invention to provide a throttle sensor for detecting a throttle valve opening used.

[0005]

A variable capacitor having a first structure according to the present invention includes a casing, a rotor rotatably supported by the casing, and a conductive member accommodated in the casing. And a plurality of spiral plate-shaped spiral springs whose base ends are fixed to the casing and biasing ends are fixed to the rotor, and which are concentrically wound facing each other with a gap therebetween. The spiral spring constitutes a counter electrode.

According to a second aspect of the present invention, in addition to the first aspect, the pin for fixing the base end of the spiral spring to the casing and for supplying a signal to the spiral spring and fixing the spring is further provided. It is characterized by having. A third structure of the present invention is the partition wall according to the first structure, wherein the casing divides the internal space of the casing to define a spiral spring chamber and a circuit chamber that are axially adjacent to each other. It is characterized by having.

A fourth structure of the present invention is characterized in that, in the first structure, the casing is fixed to the valve housing of the throttle valve, and the rotor is interlocked with the valve shaft of the throttle valve. .

[0008]

According to the first structure of the present invention,
At least a pair of spiral springs, the base end of which is fixed to the casing and the biasing end of which is fixed to the rotor, are wound so as to face each other with a gap in the radial direction. With this configuration, as the rotor rotates, the gap between the spiral springs that are adjacent in the radial direction decreases, and the capacitance between the spiral springs increases accordingly. In particular, according to this configuration, even if the rotation angle of the rotor exceeds 180 degrees, the electrostatic capacitance can be changed according to the rotation angle, and there is an advantage that the application range is expanded. Further, according to this configuration, if the application of the turning torque to the rotor is stopped, the rotor can automatically return to the initial position by the restoring force of the spiral spring, which is also advantageous in that it is convenient. Furthermore,
The variable capacitor of this configuration can be configured by simply locking each end of a pair of spiral springs to the casing and the rotor, and has the advantage that the number of parts is small and the structure is extremely simple.

According to a second structure of the present invention, in the first structure, the base end of the spiral spring is further fixed to a power supply pin fixed to the casing. That is, the pin for locking the base end of the spiral spring also serves as the pin for applying a voltage thereto. By doing so, it is possible to further reduce the number of parts and simplify the configuration. Third of the present invention
According to the configuration, in the first configuration, the spiral spring chamber and the circuit chamber are further formed in the casing so as to be adjacent to each other in the axial direction, and the spiral spring and the rotor are housed in the spiral spring chamber, and the circuit chamber is provided. A circuit board is housed that supplies power to the spiral spring and detects a rotation angle according to the state of the spiral spring. By doing so, the line between the spiral spring and the circuit portion can be shortened, and the stray capacitance is reduced.

In particular, if a structure is adopted in which the pin penetrates the partition wall between the two chambers, the circuit board in the circuit room may supply a predetermined voltage to this pin, and the power supply wiring from the circuit board to the spiral spring. Can be extremely simple. In one example, this pin is fitted into a through hole provided in the circuit board and electrically connected to a conductor layer around the through hole by soldering or the like. In another example, this pin can also serve as a support pin for fixing the circuit board. By doing so, the device configuration can be further simplified.

According to a fourth structure of the present invention, in addition to the above-mentioned first structure, the casing is fixed to the valve housing of the throttle valve, and the rotor is interlocked with the valve shaft of the throttle valve. It can be applied to a throttle sensor for detecting. in this case,
The spiral spring can also serve as a return spring of the valve shaft of the throttle sensor, so that the number of parts can be reduced and the structure can be simplified.

[0012]

【Example】

(Embodiment 1) FIG. 1 is a variable capacitor 1 of this embodiment.
00 is a front view when the cover plate 1c is not provided, FIG. 2 is an axial sectional view of the variable capacitor 100 of FIG. 1, and FIG. 3 is a sectional view taken along the line BB of FIG.

This variable capacitor 100 has a casing 1 made of resin. Inside the casing 1, a substantially rectangular box-shaped rotor chamber 10 and a circuit chamber 11 are axially arranged (see FIGS. 2 and 3). They are formed adjacent to each other with a partition wall 8 therebetween in the middle and up and down directions. Each of the rotor chamber 10 and the circuit chamber 11 is opened on the side opposite to the partition wall 8, and the connector tube portion 13 radially projects from the main portion of the casing 1 having the rotor chamber 10 and the circuit chamber 11. Collar-shaped projections 1 a for fixing the casing 1 are provided so as to project from the main portion of the casing 1 on both sides in the radial direction perpendicular to the connector tube portion 13. A hole 28 for fastening is formed in each of the flange-shaped projections 1a in the axial direction.

A lid plate 1c having an opening 1b is provided on the end surface of the casing 1 located on the side opposite to the partition wall 8 with the rotor chamber 10 interposed therebetween, and the lid plate 1c is annular around the opening 1b. It has a protrusion 1d. On the other hand, a cover plate 1e for closing the opening of the circuit chamber 11 is provided on the end surface of the casing 1 located on the side opposite to the partition wall 8 with the circuit chamber 11 interposed therebetween. A cylindrical rotor 2 made of resin is provided in the rotor chamber 10, and a pair of spiral springs formed in a spiral plate shape with the biasing end 6 being locked in a locking groove 7 on the outer peripheral surface of the rotor 2. 3 and 3 are rotatably held. Overhanging portions 4 for pin support extend from the casing 1 to the rotor chamber 10 at two opposite corners of the rotor chamber 10, and the pin 5 is inserted into the hole of the overhanging portion 4 by insert molding or press fitting. Are integrally fixed in the axial direction, and hook-shaped base ends 9 of both spiral springs 3 are individually formed on both pins 5. As a result, when the rotor 2 is rotated in FIG. 1, the spiral spring 3 is deformed in the winding tightening direction, and the rotor 2 is biased in the B direction by the elastic force for recovering this deformation. A notch 15 into which a connecting portion 19 of a valve shaft 17, which will be described later, is fitted, is formed in the central portion in the radial direction of the rotor 2.
15 is formed by double chamfering.

A corrugated washer spring 22 is housed between the rotor 2 and the partition wall 8. Washer spring 22
Urges the rotor 2 toward the partition 8 opposite to the axial direction.
A circuit board 12a housed in a metal box 12 for electromagnetic shielding is housed in the circuit room 11 while being electrically insulated from the metal box 12, and a terminal 12b of the circuit board 12a is connected to a terminal 14 extending to a connector tube portion 13. It is connected.

The pair of pins 5 extend through the partition wall 8 in the axial direction and project into the metal box 12 while being electrically insulated from the metal box 12, and are connected to the circuit board 12a by a conductor (not shown).
A spiral spring 3 integrally formed with the rotor 2 is arranged in the casing 1 connected to an upper terminal (not shown), and the rotor 2 is rotated by the rotation of a valve shaft 17 described later. At times, the spiral spring 3 is tightened, and when the valve shaft 17 returns, the rotor 2 follows the rotation of the valve shaft by the elastic force of the spiral spring 3. As a result, the gap between the pair of spiral springs 3 changes, and the electrostatic capacitance between both springs 3 changes according to the rotation angle of the rotor 2.

FIG. 4 shows an example of a circuit mounted on the circuit board 12a. The rectangular wave voltage having a predetermined frequency output from the oscillator 200 is applied to the base of the transistor Tr2. A constant current is supplied to the collector of the transistor Tr2 through the charging / discharging unit 20. Eventually, the variable capacitor C0, which is composed of the electrostatic capacitance between the pair of spiral springs 3, is repeatedly charged with a constant current at the above frequency and discharged by the transistor Tr2, and the terminal voltage V1 of the variable capacitor C0 is repeated.
The peak value of changes depending on its impedance. Then, the peak value of the terminal voltage V1 is determined by the peak detection unit 202.
After being detected by, the output section 203 prepares the data and sends it to the ECU (engine control unit).

Next, an embodiment in which the variable condenser 100 described above is used as a throttle position sensor (also referred to as a throttle sensor) will be described with reference to FIGS. 5 and 6. FIG. 5 is a cross-sectional view of the throttle valve 300 in the axial direction (the direction perpendicular to the air flow), and FIG.

A valve shaft 17 is rotatably supported via a bearing 18 on a throttle body 23 through which a throttle bore 16 formed of a cylindrical hole as an intake passage is formed.
A disc-shaped valve plate 17a is fixed to the valve shaft 17.
The variable condenser 100 is installed on the throttle body 23.
A cylindrical hole 20 for centering is formed in the end face on the side, and a connecting portion 19 at the tip of the valve shaft 17 projects at the center of the cylindrical hole 20. The connecting portion 19 has two chamfers, and is fitted into the groove between the notched surfaces 15 of the rotor 2 shown in FIGS. It rotates in conjunction with the shaft 17.

FIG. 6 shows the throttle body 23 shown in FIG.
2 is a side view of the valve shaft 17 and shows a state in which a connecting portion 19 is provided on the tip of the valve shaft 17 by chamfering two. Reference numeral 20 is a recess formed on the side surface of the throttle body 23. Reference numeral 21 denotes a screw hole formed on a side surface of the throttle body 17 for attaching a sensor. The variable capacitor 100 shown in FIGS. 1 to 3 is fixed to the throttle body 23 by fitting the screw 101 into the hole 28 and then fastening the screw 101 into the screw hole 21 of the throttle body 23.

At this time, the annular projection 1c is fitted into the cylindrical hole 20 so that the shaft 17 and the rotor 2 are aligned with each other. When the variable condenser 100 is fixed to the throttle body 23, the connecting portion 19 does not come into contact with the bottom surface of the groove between the notches 15 of the rotor 2, and the washer spring 22 urges the rotor 2 to urge. Has become.

In the above structure, when the valve shaft 17 is rotated and the connecting portion 19 is rotated around the center of the valve shaft 17, the rotor 2 is rotated by winding the spiral spring 3 between the pair of spiral springs 3. When the rotation of the valve shaft 17 returns to its original value, the rotor 2 is rewound in conjunction with the valve shaft 17, and the capacitance decreases. The surface of the spiral spring 3 made of, for example, a spring material having good conductivity may be coated with an insulating resin by coating, adhesion or the like in order to improve electric insulation. The insulating resin coating may be provided on both spiral springs 3 or only on one spiral spring 3.

(Embodiment 2) Another embodiment will be described with reference to FIG. In this embodiment, four spiral springs 3a to 3d are provided.
And the pins 5a to 5d are provided. These spiral springs 3 are wound in a quadruple manner, and the pins 5 to which the base ends of the spiral springs 3 are locked are fixed to the four corners of the rotor chamber 10. The energizing ends of the spiral spring 3 are locked to the outer peripheral surface of the rotor 2 at 90 degrees apart from each other. Of course, also in this case, the same voltage is applied to the pins 5a and 5c, and the same voltage is applied to the pins 5b and 5d.

In this way, the electrostatic capacity can be increased. (Embodiment 3) Another embodiment will be described with reference to FIG. In this embodiment, one of the pair of spiral springs 3a, 3b facing each other with a predetermined gap is made narrower than the other.

In this way, both spiral springs 3a,
Even if the 3b is relatively displaced in the axial direction, it is possible to obtain an effect that the variation in the capacitance due to the displacement is reduced.
In the above embodiment, the example in which the spiral variable capacitor 100 is used as the throttle sensor has been described, but the variable capacitor 100 is used as the steering angle sensor that detects the turning angle (steering angle) of the steering shaft of the vehicle or the like. You can also

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a variable capacitor of the present invention, which is a sectional view taken along the line AA of FIG.

FIG. 2 is an axial sectional view showing an embodiment of the variable capacitor of FIG.

3 is a cross-sectional view of the variable capacitor of FIG. 1 taken along the line BB.

FIG. 4 is a circuit diagram of a circuit mounted on the circuit board of FIG.

5 is an axial sectional view of a throttle valve using the variable condenser of FIG.

FIG. 6 is a plan view of the throttle valve of FIG.

FIG. 7 is a schematic front view of a variable capacitor of Example 2.

FIG. 8 is a perspective view of a main part of a variable capacitor according to a third embodiment.

[Explanation of symbols]

1 is a casing, 2 is a rotor, 3 is a spiral spring, 5 is a pin, 8 is a partition wall, 10 is a spiral spring chamber, and 11 is a circuit chamber.

Claims (4)

[Claims] 1. A casing, a rotor rotatably supported by the casing, and a conductive member that is housed in the casing and has a base end fixed to the casing and an urging end that is the rotor. And a plurality of spiral plate-shaped spiral springs fixed to each other, wherein the plurality of spiral springs concentrically wound facing each other with a gap therebetween constitute a counter electrode. . 2. The variable capacitor according to claim 1, further comprising a pin for fixing a base end of the spiral spring fixed to the casing and for supplying a signal to the spiral spring and fixing the spring. 3. The variable capacitor according to claim 1, wherein the casing has a partition wall that divides an internal space of the casing to define a spiral spring chamber and a circuit chamber that are axially adjacent to each other. 4. The variable capacitor according to claim 1, wherein the casing is fixed to a valve housing of a throttle valve, and the rotor is interlocked with a valve shaft of the throttle valve.