JPH0138485Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation angle detection device that detects the rotation angle of a rotating body that rotates in synchronization with a rotation shaft (crankshaft) or the like of an internal combustion engine.

Conventionally, there is one shown in FIG. 1 as this type of device. In FIG. 1, reference numeral 1 denotes a magnetic rotating body having a large number of magnetic poles formed around its circumference, and is fixed to a drive shaft 2 that rotates in synchronization with an internal combustion engine. 3 is a magnetic detection element (for example, a Hall element) that outputs a signal in synchronization with the rotating body 1; 5 is a differential amplifier that amplifies the signal to obtain a signal voltage indicated by a in FIG. 3; and 6 is a comparison device. 41 to 46 are resistors, 10 is an amplifier circuit, 2
0 is an integration circuit, and 30 is a comparison circuit. and,
The signal from the magnetic detection element 3 is amplified by an amplifier 5 and input to one input terminal of a comparator 6. The other component is integrated by a resistor 44 and a capacitor 47 with a sufficiently long time constant relative to the period of the input signal, and becomes a DC component indicated by b in FIG. When this is input to the other input terminal of the comparator 6 and the comparator 6 is activated, a rectangular wave indicated by c in FIG. 3, which is inverted at the center of the sine wave, is obtained.

However, in the conventional system described above, the rotating body 1
When the rotation speed of the amplifier 5 is extremely low and the output period of the amplifier 5 is long as shown by a in FIG. As a result, the detection position is shifted as shown by c in FIG. 4. Furthermore, when the rotating body 1 is stopped, the integral value and the output potential of the amplifier 5 are at the same potential, which may cause the comparator 6 to oscillate, and there is a drawback that detection at zero rotation is impossible.

In order to correct the above-mentioned drawbacks, this invention has a circuit that fixes the integral value of the integration circuit to a constant voltage at extremely low rotations, thereby improving the accuracy of angle information at extremely low rotations, and improving the precision of angle information at extremely low rotations. The purpose is to be able to operate reliably until the end.

The present invention will be described below with reference to embodiments shown in the drawings. In Fig. 2, 1 is a magnetic rotating body, 2 is a drive shaft, 3 is a magnetic detection element, 5 is an amplifier, 6 is a comparator, 10 is an amplifier circuit, 20 is an integration circuit, 30 is a comparison circuit, and 40 is a fixed voltage circuit, 41 to 46 are resistors, 47 are capacitors, 71 to 75 are resistors, 70
is a phase inversion circuit (inverter), 77 is a PNP transistor, and 78 is an NPN transistor. 8
is a rotation speed detection circuit for detecting the rotation speed of the rotating body 1, 81 and 82 are capacitors, 83 and 84 are diodes, 85 to 88 are resistors, and 80 is a comparator.

Next, the operation of the above configuration will be explained.
The rotation speed of the rotating body 1 is determined by the resistance 44 and the capacitor 47.
is sufficiently higher than the time constant of , the output of comparator 80 is low level and transistors 77 and 78 are OFF.
, and a resistor 4 is connected to the positive input terminal of the comparator 6.
4 and the capacitor 47 are sent, and the waveforms of each part are as shown in FIG. 3, which is similar to the conventional example shown in FIG.

The rotation speed is a predetermined value (for example, the engine rotation speed is 300 rotations)
If the voltage is lower, the voltage that has been frequency-voltage converted by the capacitors 81, 82 and the diodes 83, 84 will be lower than the voltage set by the resistors 87 and 88, and the output of the comparator 80 will be at a high level, and the transistors 77, 78 turns on. Here, the resistance 71
If the resistance value of is selected to be sufficiently larger than the resistance value of resistors 73 and 74, the voltage at point d will be approximately equal to that of resistor 73.
It is determined by the partial pressure ratio of 74. If the voltage d resulting from the voltage division of the resistors 73 and 74 is set to be approximately at the center of the sine wave (slightly above the center e in FIG. 5) as shown by d in FIG. c shown in Figure 5, which is inverted approximately at the center of the sine wave as an output.
A rectangular wave shown by is obtained, and angle detection at zero rotation is also possible. In FIG. 5, a is the output signal of the amplifier 5 which amplifies the output of the magnetic detection element 3;
b is the terminal voltage of the capacitor 47.

In the embodiment described above, the rotation speed detection circuit 8 includes a rotation speed-voltage conversion circuit and a comparator 8.
0 is used, but other methods may be used. For example, in a device that detects the rotation angle of an automobile internal combustion engine, the neutral point voltage of an alternator rotated by the internal combustion engine, the on/off state of a charge lamp relay, etc.
The rotational speed may be detected by turning on and off the hydraulic switch, or in some cases, the voltage at the positive input terminal of the comparator 6 may be set to a fixed voltage only when the starter switch is activated.

As described above, the present invention has the following excellent effects.

(1) In the region of high rotation speed, since the integral method uses the center of the sine wave as the inversion position, the rotation angle can be detected with high accuracy.

(2) Since the angular accuracy at low rotations is set with a fixed voltage, the angular accuracy will not deteriorate due to ripples in the integral value.

(3) If the number of rotations is specifically detected, detection at zero rotation is possible.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing a conventional device, Fig. 2 is an electric circuit diagram showing an embodiment of the device of the present invention, and Figs. 3 to 5 are waveforms of various parts for explaining the operation of the conventional device and the device of the present invention. It is a diagram. 1... Magnetic rotating body, 3... Magnetic detection element, 8, 40
...a rotational speed detection circuit and a fixed voltage circuit constituting a fixed voltage control circuit, 20...an integrating circuit, 30...a comparison circuit.

Claims (1)

[Claims for Utility Model Registration] (1) A magnetic rotating body with a large number of magnetic poles formed around its circumference,
A magnetic detection element faces the magnetic pole of this magnetic rotating body and generates an output voltage including an alternating current component as the magnetic pole moves, and the output voltage generated in this magnetic detection element is integrated to output an average value voltage. an integrating circuit that compares the average voltage of the integrating circuit with the output voltage of the magnetic detection element and outputs an angle signal; and a comparing circuit that outputs an angle signal when the rotational speed of the magnetic rotating body is below a predetermined value. A rotation angle detection device comprising: a fixed voltage control circuit that fixes an input on the integrating circuit side to a fixed voltage. (2) The fixed voltage control circuit includes a rotation speed detection circuit that detects the rotation speed of the magnetic rotating body and determines whether the rotation speed is below a predetermined value, and a rotation speed detection circuit that detects the rotation speed of the magnetic rotating body. Claims for registration of a utility model characterized by comprising: a fixed voltage circuit that fixes the input on the integrating circuit side of the comparison circuit to a fixed voltage when it is determined that the rotation speed of the rotating body is below a predetermined value. The rotation angle detection device according to item 1.