JPS63223503A - Rotational angle detector - Google Patents

Abstract

PURPOSE:To preclude misdetection by a simple structure and a simple circuit by detecting the variation of a magnetic field by a magnet ring which rotates associatively with a steering wheel, etc., by plural magneto-resistance elements which are arranged opposite the magnet ring. CONSTITUTION:A guide 6 to which the magnet ring 5 is adhered and fixed is fitted and locked in a cam 4 which rotates associatively with the rotation of the steering wheel of a vehicle. The cam 4 is fitted to a switch main body 1 by engaging a fall-preventive part 12 with the cam lock part 11 of a main body boss 10. Then a sensor unit 8 is fitted to the main body 1 so that magneto- resistance elements 13 and 13a face the ring 5 at all times. This main body 1 is fixed right below the steering wheel through the boss 10. Consequently, when the steering wheel is rotated, the cam, guide 6, and ring 5 also rotate in response to it and the intensity of the magnetic field which operates on the resistance elements 13 and 13a varies. This variation is converted by a pulse generating circuit 14 into a pulse signal, which is transferred to the controller for a microcomputer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotation angle detection device capable of detecting the amount and direction of rotation of a rotating shaft such as a steering wheel of a vehicle.

Conventional technology Conventionally, this type of rotation angle detection device for detecting the rotation of a steering shaft has two
A set of photointerrupters is installed, and the rotation angle of the steering shaft is detected by detecting the on/off pattern of light passing through the slit, and the rotation angle of the steering shaft is determined by the phase difference between the two sensors. It was like identifying.

In addition, as shown in FIG. 2 of Japanese Utility Model Publication No. 58-145506, there was also a device in which a slit plate similar to the Shibetsu was provided inside the annular box just below the handle, and a photo interrupter was placed as a sensor.

Problems to be Solved by the Invention The method of attaching sensor elements such as photointerrupters to the steering shaft has poor assembly workability;
In addition, a method in which a similar sensor is built into an annular box is
The problem is that the box is large and space-efficient.Furthermore, the optical detection method that uses a combination of a photointerrupter and a slit has the problem that the light is blocked by dust or lubricant in the rotating parts, resulting in false detection. In order to prevent this from happening, it was necessary to pay attention to the robust exterior and the method of filling the lubricant.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a cam which is rotated by the vehicle handle and is locked to the main body via a spring, and a cam which is disposed directly below the cam. , a substantially ring-shaped magnet fixed by a guide rotated by the cam, one or more magnetoresistive elements opposed to the magnet, and a sensor detected by these magnetoresistive elements. The rotation angle detection device is constructed by a circuit that converts changes in the magnetic field into pulse signals.

Function: With the above-described configuration, the magnetic resistance element arranged as a sensor detects the passage of a magnetic field and suppresses voltage fluctuations with respect to the rotational movement of a magnet ring that is locked to a cam that rotates in conjunction with a handle, etc. The voltage fluctuations are converted into pulses and transmitted to an external control device such as a microcomputer. The control device detects the amount of rotation by the number of pulses and the direction of rotation by the phase difference between the two pulses.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a switch body which is placed directly below the handle and is fixed to an ignition key unit or the like. 2 is a switch unit for turn signals, lights, etc., which is operated by the operating unit 2&; 3 is a switch unit, such as a wiper, washer, etc., which is operated by the operating unit 3a. The cam is biased upward by a 4Fi spring 9, engages with a handle disposed above (not shown) through cam pins 41L, 4b, and 40, and rotates in response to the rotation of the handle.

Reference numeral 6 denotes a magnet ring that is engaged with or adhesively fixed to the guide 6, and the position of the protrusion 71L of the magnet ring 5 is regulated by the protrusion 7b of the guide 6. The lower end portion 21 of the guide 6 has a brim shape that spreads around the outer periphery, and is guided by one or more pawl portions 22 provided on the main body 1, so that it can freely rotate while being restricted from vertical movement. It has become. Further, the lower protrusion 24 of the cam 4 is fitted and locked into the upper surface recess 23 of the guide 6, so as to correspond to the rotation of the cam 4. In order to prevent the cam 4 from being detached before it is attached to the handle, a retaining portion 12 provided on the cam 4 engages with a cam locking portion 11 provided on the main body boss 1o. 8 is a sensor unit consisting of two magnetoresistive elements.

Here, the magnetic resistance element of the sensor unit 8 needs to be arranged so as to almost face the magnet ring 6, but when the cam 4 is attached to the steering wheel, due to the structure of the automobile assembly, the cam 4 has a vertical direction of ± Since there is an error in the assembly of about 2 to 3 centimeters, when the magnet ring 6 is attached to the cam 4, there is a risk that it will not face the magnetic resistance element of the sensor unit 8.
, it is necessary to increase the dimension in the thickness direction of the magnet ring 6, which increases the size of the structure and increases the cost. Therefore, the guide 6 that holds the magnet ring 6 and the cam 4 are separated, and the guide 6 is separated from the cam 4. It has a structure in which it is locked by a claw part 22 of the main body, restricts the vertical movement of the magnet ring 6, and always faces the magnetoresistive element of the sensor unit 8. In addition, the lower protrusion 24 of the cam 4 and the upper recess 23 of the guide 6 have a dimensional relationship such that the cam 4 will not come off even if it is moved up and down within the installation error range (±2 to 3 sm) and will be reliably engaged. It has become.

The magnet ring 5 and guide 6 described above may be integrally constructed by using a plastic magnet or the like for the magnet ring 6.

FIG. 5 is a detailed view of the magnet ring 5, which is made of a magnet or a resin magnet, and is oriented in the radial direction in advance and has a certain number of N and 8 poles magnetized on its outer periphery. .

In FIG. 6, 16 is a sensor consisting of a magnetoresistive element 13 and a pulse generation circuit 14 (detailed circuit configuration is shown in FIG. 8), and a sensor 161L is similarly composed of a magnetoresistive element 13& and a pulse generation circuit 14a. In this embodiment, if the magnetization width of the N to S poles is I p l", the pitch of the two magnetoresistive elements 13.1:3a is " p
/ 4'''.

FIG. 8 shows the structure of the magnetoresistive element 13 and the configuration of the pulse generation circuit. The magnetoresistive element 13 is connected to the power supply VC
A constant voltage (for example, 5 V) is supplied to C and T2, and resistor R1 is connected to the negative side of comparator 19 via R1 at a point where it becomes equal to R2. Further, T3 is grounded. 17 is a circuit for generating a reference voltage for comparison in the comparator 19 when the magnetoresistive element 13 generates a voltage change due to a change in the magnetic field due to the passage of the N or S pole, and is connected to the resistor R3. The resistor R3 is connected to the power supply, and the resistor R4 is connected to the ground. Note that vRl is a variable resistor that finely adjusts the set value, and is connected to the positive side of the comparator 19. 18 is comparator 1
When generating pulses in step 9, resistors R5 and R are used to provide hysteresis to the slice voltage as shown in Figure 7 in order to prevent false detection due to chattering near the reference voltage.
6, R7 is a pull-up resistor. Reference numeral 20 is a terminal for transmitting the generated constant pulse to a control device such as a microcomputer (not shown).

The operation of one embodiment of the present invention having the above configuration will be described below. 6. For example, when the steering wheel of a vehicle (not shown) is rotated counterclockwise (direction AC in FIG. 6), the rotation of the steering wheel In response, the cam 4 and guide 6 also rotate counterclockwise,
For example, when the S pole tip 5aL of the magnet S/G 5 approaches the magnetoresistive element 13, the magnetic field acting on the magnetoresistive element 13 increases for a while, the value of the resistance R1 also decreases for a while, and the center 5C of the magnetic pole passes. Minimum when Furthermore, after 6C passes, the resistance begins to increase for a while, and reaches its maximum when the pole tip 5b passes.

In response to the above resistance change, the comparator 19
The voltage applied to is VFmin −+ Vmax −+V Fm1 of the change curve represented by the solid line of the output waveform in FIG.
change to n. The same behavior occurs when adjacent N poles pass next. Now, circuit 18 consisting of resistors R5 and R6
is configured to have hysteresis in the slice voltage level that generates pulses, so VFmin→V
When the voltage changes max, the pulse rises at the upper slice voltage vSU, and when it changes to Vmax - + VFmin, it falls at the lower slice voltage VSL.

By repeating the above behavior, the output 2om generates a pulse like the output pulse shown in FIG. Magnetoresistive element 13
4 shows similar behavior, but its voltage waveform (illustrated by dotted line)
The output pulse will be out of phase with the magnetoresistive element 13 by 1)/4 due to the dimensions of the element arrangement.

Therefore, the sensors 16 and 16m transmit their respective pulse signal outputs 20m and 20B according to the above behavior to a control device such as a microcomputer (not shown).

Conversely, when the handle rotates clockwise, sensor 1
The timings of generation of pulses 6 and 16a are reversed, and the pulses are transferred to a control device such as a microcomputer (not shown).

The control device calculates the rotation amount of the knob from the number of pulses.
Further, the rotation direction can be calculated and detected from the timing of generation of pulses from the sensors 16 and 161L.

Effects of the Invention As described above, according to the present invention, it is possible to provide a rotation angle detection device that has an extremely simple structure and circuit, and does not require consideration of false detection caused by dust or lubricant.

In addition, the cam and the guide that holds the magnet ring are separated, and the magnet ring and the magnetic resistance element are always facing each other, making the attachment to the handle more reliable. This enables detection.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is an exploded perspective view thereof, Figs. 3 and 4 are sectional views of essential parts of an embodiment of the invention, and Fig. 5 is a magnet ring. Detailed top view, Figure 6 is an enlarged top view of a part of the magnet ring and sensor, Figure 7 is a waveform diagram of the main part,
FIG. 8 is a circuit diagram of the sensor. 1...Body, 4...Cam, 5...
...Magnet ring, 6...Guide, 8...
・Sensor unit, 13°132L...Magnetic resistance element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure ＋＋１＋＋＋ ″″ゞ」95ゝ 4 ~ , Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] A cam that is rotated by the vehicle handle and is locked to the main body via a spring, and a substantially ring-shaped magnet that is placed directly below the cam and fixed to a guide that is rotated by the cam. and one or more magnetoresistive elements opposed to this magnet body,
A rotation angle detection device consisting of a circuit that converts changes in the magnetic field detected by these magnetoresistive elements into pulse signals.