JP2001108700A - Rotational body reverse rotation detection device and reverse rotation detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reverse rotation detecting device and a reverse rotation detecting method for a rotating body, which can reduce the manufacturing cost, increase the degree of freedom of layout, and can be configured compactly. SOLUTION: In a reverse rotation detection device 1, a midpoint potential SV1 representing a change in a magnetic field generated between a magnet 4b and a tooth Ga of the gear G with the rotation of the gear G by an MR element 4a.
Is output. The phase shifter 6 is based on the midpoint potential SV1,
The comparator 7 generates two signals SV3 and SV4 having a predetermined phase difference, and the comparator 7 compares the signals SV3 and SV4 to detect a direction in which the midpoint potential SV1 increases or decreases. D-
The flip-flops 10, 11 increase or decrease based on the output signal SV5 of the comparator 7 while the midpoint potential SV1 stays in one of a region exceeding the lower limit value VL of the hysteresis and a region lower than the upper limit value VL of the hysteresis. It is detected whether the direction has been reversed a plurality of times and the signals SV7, S7
V8 is output. The microcomputer 15 outputs the output S
Based on V7 and SV8, it is detected whether or not the rotation direction of the rotating body is reversed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body reverse rotation detecting device and a reverse rotation detecting method for detecting the presence or absence of a reverse rotation of a rotating body.

[0002]

2. Description of the Related Art Conventionally, as this kind of rotating body reverse rotation detecting apparatus, there is known an apparatus described in Japanese Patent Application Laid-Open No. 10-227809. The apparatus for detecting reversal of a rotating body includes a magnet rotor attached to a rotatable rotating body, a magnetoresistive element arranged in a magnetic field of the magnet rotor and outputting a detection signal indicating a change in the magnetic field, and a magnetoresistive element. And an arithmetic circuit to which the detection signal is input. On the outer peripheral surface of the magnet rotor, a large number of magnetic poles composed of N poles and S poles are alternately arranged, and these many magnetic poles include one first magnetic pole having the strongest magnetic force among them, The second magnetic pole is arranged next to the first magnetic pole, and includes a plurality of third magnetic poles which are weaker than these two magnetic poles and have the same magnetic force as each other.

In this reverse rotation detecting device for a rotating body, when a large number of magnetic poles pass near the magnetoresistive element due to the rotation of the magnet rotor, the detection signal output from the magnetoresistive element changes as the magnetic field changes. Voltage drop and voltage rise are repeated accordingly. In particular, when the first and second magnetic poles pass, the voltage drops to a greater degree than the other third magnetic poles. Then, the arithmetic circuit detects the order of occurrence of the two voltage drops corresponding to the first and second magnetic poles, and detects the rotation direction of the magnet rotor based on the two orders. Is detected.

[0004]

According to the above-mentioned conventional reverse rotation detecting device for a rotating body, a special magnet rotor in which a large number of three types of magnetic poles having different magnetic forces are arranged in order to detect the presence or absence of reverse rotation in the rotating direction. Must be used. Therefore, there is a problem that the manufacturing cost is increased. Also,
A reverse rotation detection that detects the presence or absence of a reverse rotation in the rotation direction of the rotating body by using a gear rotor made of a magnetic material instead of such a special magnet rotor and detecting the rotation of the gear rotor with a plurality of magnetic detection sensors. Devices are also known. However, in this reverse rotation detection device, since a plurality of magnetic detection sensors must be used, a space for arranging the plurality of magnetic detection sensors is required, and the degree of freedom in the layout of the device is low. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has an apparatus for detecting a reverse rotation of a rotating body, which can reduce manufacturing costs, increase the degree of freedom in layout, and can be made compact. It is intended to provide a detection method.

[0006]

In order to achieve this object, an invention according to claim 1 is to determine whether or not there is a reversal of the rotation direction of a rotating body (for example, an axle in the embodiment (hereinafter the same in this section)). A reverse rotation detection device 1 for a rotating body (axle) to be detected, which is made of a magnetic material, rotates with the rotation of the rotating body (axle), and is arranged on the outer peripheral surface at intervals along the rotation direction. Magnetic field generating means (magnet 4) for generating a magnetic field between a rotatable gear (gear rotor G) having a plurality of teeth Ga and a tooth Ga of the gear (gear rotor G).
b), a magnetic detection means (MR element 4a) for outputting a detection signal (middle point potential SV1) indicating a change in a magnetic field accompanying rotation of the gear (gear rotor G), and detection of the magnetic detection means (MR element 4a) Two electric signals (signal SV) having a predetermined phase difference between each other based on the signal (midpoint potential SV1)
3, SV4), a signal generating means (phase shifter 6),
By comparing these two electric signals (signals SV3 and SV4), an increasing / decreasing direction detecting means (comparator 7) for detecting an increasing / decreasing direction of the detection signal (middle point potential SV1) and an increasing / decreasing direction detecting means (comparator 7) Based on the detection result (signal SV5), the region where the detection signal (midpoint potential SV1) exceeds the reference value (the region above the lower limit value VL of the hysteresis) and the region below the reference value (the region below the upper limit value VL of the hysteresis) ), The detection signal (the midpoint potential SV1) increases or decreases several times (three times).
Inversion detection means (D-flip-flops 10, 11) for detecting whether or not the inversion has occurred, and the detection result (signal SV) of the inversion detection means (D-flip-flops 10, 11)
7, SV8), a reverse rotation detecting means (D-flip flop 12, EX_OR14, microcomputer 1) for detecting the presence or absence of reverse rotation of the rotating body (axle) in the rotation direction.
5).

According to the apparatus for detecting reversal of a rotating body, a magnetic field is generated between the teeth of a gear made of a magnetic material by a magnetic field generating means such as a magnet. The strength of this magnetic field is
Since the teeth of the gear are arranged at intervals, the gear changes according to the rotation of the gear accompanying the rotation of the rotating body, and the magnetic detection means outputs a detection signal indicating the change in the strength of the magnetic field. . Therefore, in a state where the rotating body is rotating in the same direction, the value of the detection signal detected by the magnetic detection means has a characteristic of regularly increasing and decreasing between the maximum value and the minimum value. On the other hand, when the rotating body rotates in the reverse direction from the same direction, the value of the detection signal is inverted without the increase or decrease direction reaching the maximum value or the minimum value, in other words, the maximum value and the minimum value. Multiple times before crossing a reference value that is between
It shows the characteristic of reversing. Therefore, based on the characteristics of the detection signal as described above, the increase / decrease direction of the detection signal is detected by comparing the two electric signals having a phase difference generated based on the detection signal of the magnetic detection means with the increase / decrease direction detection means. In addition, the above-mentioned reference value is appropriately set, and while the detection signal stays in one of the region above the reference value and the region below this reference value, it is inverted whether or not the increase / decrease direction has been inverted several times. By detecting with the detecting means,
The presence or absence of the reversal of the rotation direction of the gear, that is, the presence or absence of the reversal of the rotation direction of the rotating body can be accurately detected.

Further, a magnet rotor such as a conventional reverse rotation detecting device for a rotating body is not required, and can be configured by simply adding a simple circuit to an existing detecting device having a gear rotor, and it is also necessary to newly add a sensor. Absent. This allows
The manufacturing cost can be reduced, and the entire apparatus can be made compact. Further, by configuring the magnetic detection means with one magnetic detection sensor, the degree of freedom in the layout of the apparatus can be increased as compared with a conventional apparatus using a plurality of magnetic detection sensors, and the entire apparatus can be made more compact. Can be configured.

According to a second aspect of the present invention, in the reverse rotation detecting device for a rotating body (axle) according to the first aspect, the reference value has a hysteresis of a predetermined width (a width between the lower limit value VL and the upper limit value VH). It is characterized by having.

According to the reverse rotation detecting device for the rotating body, it is possible to prevent chattering of the signal indicating the detection result by the reverse detecting means, and to stably detect the presence or absence of the reverse rotation in the rotation direction. Further, it is possible to more appropriately detect a state in which the increase / decrease direction is reversed, that is, a state in which the rotation direction of the rotating body is reversed, without the value of the detection signal reaching the maximum value or the minimum value. From this viewpoint, it is preferable that the predetermined width of the hysteresis is set as large as possible between the maximum value and the minimum value of the detection signal.

According to a third aspect of the present invention, there is provided a method for detecting reversal of a rotating body (axle) for detecting the presence or absence of a reversal of the rotating direction of the rotating body (axle). A gear (gear rotor G) is provided which has a plurality of teeth Ga arranged at intervals along the rotating body (axle), and is rotatable with the rotation of the rotating body (axle).
a detection signal (midpoint potential SV1) representing a change in the magnetic field accompanying the rotation of the gear (gear rotor G).
, And two electric signals (signals SV3 and SV4) having a predetermined phase difference between each other are generated based on the detected detection signal (midpoint potential SV1), and these two electric signals (signals SV3 and SV3) are generated. SV4), the direction of increase or decrease of the detection signal (midpoint potential SV1) is detected, and based on the detected direction of increase or decrease of the detected signal (midpoint potential SV1), the detection signal (midpoint potential SV1) is set to a reference value. While the detection signal (midpoint potential SV1) increases / decreases while staying in one of the region (region exceeding the lower limit value VL of hysteresis) and the region smaller than the reference value (region below the upper limit value VL of hysteresis). Is detected multiple times (three times),
Based on the presence / absence of multiple (three) inversions in the increase / decrease direction in the detected detection signal (midpoint potential SV1), the presence / absence of reversal of the rotation direction of the rotating body (axle) (the output SV10 of the D-flip-flop 12 (The presence or absence of a change).

According to this method of detecting the reversal of the rotating body, the manufacturing cost of the apparatus for implementing this method can be reduced, the degree of freedom in the layout of the apparatus can be increased, and the entire apparatus can be made compact.

According to a fourth aspect of the present invention, in the method for detecting reverse rotation of a rotating body (axle) according to the third aspect, the reference value has a hysteresis of a predetermined width (a width between the lower limit value VL and the upper limit value VH). It is characterized by having.

According to the method for detecting the reverse rotation of a rotating body, it is possible to stably detect the presence or absence of a reverse rotation in the rotating direction as in the above-described reverse rotation detecting apparatus for a rotating body, and to more appropriately detect a state in which the rotating direction of the rotating body reverses. Can be detected.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a rotating body reverse rotation detecting apparatus according to an embodiment of the present invention. 1 and 2 show a schematic configuration of a rotating body reverse rotation detecting device according to the present invention. This reverse rotation detection device 1
It detects whether or not the rotation direction of the gear rotor G has been reversed, and includes a sensor circuit 2 and a detection circuit 3 connected to the sensor circuit 2. As shown in FIGS. 3 and 4, the gear rotor G is a steel gear, which is a magnetic material, and is attached so as to rotate integrally with an axle (not shown) of an automobile as a rotating body. Further, on the outer peripheral surface of the gear rotor G, a number of teeth Ga (only one is shown) are arranged at predetermined regular intervals.

Next, the sensor circuit 2 will be described. The sensor circuit 2 includes a sensor unit 4 including two MR elements 4a and 4a and a magnet 4b, a comparator 5 and a phase shifter 6 (phase shifter) connected to the sensor unit 4.
r) and a comparator 7 connected to the phase shifter 6.

The MR elements 4a, 4a (magnetic detecting means)
This is a magneto-resistive element made of a semiconductor, and is arranged opposite to the gear rotor G and at a predetermined interval from the teeth Ga of the gear rotor G as shown in FIGS. The magnet 4b (magnetic field generating means) of the sensor unit 4
Are arranged at positions where a magnetic field is generated between the teeth Ga of the steel gear rotor G, which is a magnetic material, when the teeth are approached, and each MR element 4a is located within the generated magnetic field. Are arranged as follows. Further, the MR elements 4a,
4a is connected in series between the VCC circuit 8 of the detection circuit 3 and the ground, and two resistors R1 and R2 are connected in series between the VCC circuit 8 and the ground. These resistors R1 and R2 are set to the same value as each other, and are provided in parallel with the MR elements 4a and 4a.

The midpoint between the MR elements 4a, 4a is connected to the inverting input terminal of the comparator 5, and the resistors R1, R
The middle point of 2 is connected to the non-inverting input terminal of the comparator 5. The output terminal of the comparator 5 is connected to the non-inverting input terminal via the resistor R3. The positive feedback is applied to the comparator 5 so that the comparator 5 forms a Schmitt trigger circuit having hysteresis. . As shown in FIGS. 3 and 4, the hysteresis has a predetermined width defined by a predetermined upper limit value VH and a predetermined lower limit value VL. The output terminal of the comparator 5 is connected to the waveform shaping circuit 9 of the detection circuit 3 described later and the D terminals of the two D-flip flops 10 and 11.

Further, the phase shifter 6 (signal generating means) includes a comparator 6a and two CR delay circuits 6b and 6c. The output terminal of the comparator 6a is connected to the inverting input terminal, and the comparator 6a forms a buffer circuit due to the negative feedback. The output terminal of the comparator 6a is C
R delay circuits 6b and 6c.
Output terminals of the delay circuits 6b and 6c are connected to an inverting input terminal and a non-inverting input terminal of the comparator 7, respectively. The output terminal of the comparator 7 is connected to an inverter 13 and a D-flip flop 11 of the detection circuit 3 described later.
Clock terminal.

Next, the detection circuit 3 will be described. The detection circuit 3 includes a VCC circuit 8, a waveform shaping circuit 9, and three D-
Flip flops 10, 11, 12 and inverter 1
3. EX_OR 14 (EXCLUSIVE OR) and microcomputer 15 (hereinafter referred to as “microcomputer 15”). The VCC circuit 8 is a power supply circuit connected to the above-described MR element 4a and the resistor R1, and supplies power thereto. The waveform shaping circuit 9 is connected to the output terminal of the comparator 5.

The D-flip flop 10 (inversion detecting means) has a clock terminal connected to the output terminal of the comparator 7 described above, and a D terminal connected to the output terminal of the comparator 5 described above. Further, the clock terminal of the D-flip flop 11 (inversion detecting means) is connected to the output terminal of the comparator 7 via the inverter 13, and the D terminal is connected to the output terminal of the comparator 5. These D-flip flops 10, 1
1 is connected to the input terminal of EX_OR14 (reverse rotation detecting means), and the output terminal of EX_OR14 is
It is connected to the clock terminal of the D-flip flop 12 (reverse rotation detecting means).

Further, the Q of the D-flip flop 12
The BAR terminal is connected to the D terminal, and the Q terminal is connected to the input port of the microcomputer 15 (reverse rotation detecting means).
The microcomputer 15 includes a CPU, a RAM, a ROM, and the like (not shown).

In the sensor circuit 2 of the reverse rotation detecting device 1 as described above, as shown in FIG. 3A, the gear rotor G rotates in the direction of the arrow A1 in the figure (from left to right in the figure). Then, as the teeth Ga of the gear rotor G approach the left half of the magnet 4b from the left side in the figure, the magnetic field between them increases. As a result, the resistance value of the left MR element 4a increases, as shown in FIG.
The midpoint potential SV1 (detection signal) between the R elements 4a, 4a drops. When the value of the dropped midpoint potential SV1 falls below the lower limit value VL of the hysteresis of the comparator 5, the output SV2 of the comparator 5 changes from the “Low” level (hereinafter simply referred to as “L”) to the “High” level (hereinafter referred to as “L”). Hereinafter, simply referred to as “H”).

Thereafter, when the gear rotor G further rotates in the direction of the arrow A1, the resistance value of the left MR element 4a further increases, and the teeth Ga of the gear rotor G change the left MR element 4a.
, That is, when the center of the tooth Ga is located on a line connecting the rotation center of the gear rotor G and the center of the MR element 4a. Thereafter, when the gear rotor G further rotates in the same direction and moves away from the left MR element 4a, its resistance value starts to decrease, and the midpoint potential SV1 increases accordingly. Then, as the teeth Ga of the gear rotor G approach the right half of the magnet 4b, the magnetic field therebetween increases, and accordingly, the right MR element 4
The resistance value of “a” increases. As a result, the value of the midpoint potential SV1 further increases, and the above-described hysteresis upper limit value VH
, The output SV2 of the comparator 5 changes from “L” to “H”.

Thereafter, when the gear rotor G further rotates in the same direction, the resistance value of the right MR element 4a increases and becomes maximum when the teeth Ga of the gear rotor G come closest.
Thereafter, when the gear rotor G further rotates in the same direction and moves away from the right MR element 4a, its resistance value starts to decrease, and accordingly, the midpoint potential SV1 drops. The midpoint potential SV1 and the output SV2 of the comparator 5 change as described above, and such changes are repeated periodically every time the teeth Ga of the gear rotor G pass.

On the other hand, the rotation direction of the gear rotor G is shown in FIG.
In the case where the rotation is reversed as indicated by the arrow A2 in (a), that is, when the tooth Ga of the gear rotor G approaches the left MR element 4a from the left and the rotation direction is reversed before approaching the MR element 4a most, First, as the teeth Ga of the gear rotor G approach the MR element 4a on the left side from the left side, the resistance value increases, and as shown in FIG.
V1 drops. Thereafter, when the rotation direction of the gear rotor G reverses, the midpoint potential SV1 starts to increase before falling below the lower limit value VL of the hysteresis. For this reason, FIG.
As shown in (c), the output SV2 of the comparator 5 is
The state is kept at “L”.

The rotation direction of the gear rotor G is shown in FIG.
When the gear rotor G reverses as shown by the arrow A3 in (a), that is, when the gear Ga reverses to the left after the tooth Ga has passed the left MR element 4a, the tooth Ga changes to the left MR.
As the element approaches the element 4a, its resistance value increases, and as shown in FIG.
Descends. Thereafter, the gear rotor G is connected to the left MR element 4.
When the value further approaches “a”, the output SV2 of the comparator 5 changes from “L” to “H” when the lowered midpoint potential SV1 falls below the lower limit value VL of the hysteresis, as shown in FIG. .

After the output SV2 changes in this way, when the gear rotor G further rotates to the right, the left MR element 4
a, the midpoint potential SV1 drops most at the position closest to
The rotation direction of the gear rotor G is reversed at a position on the right side beyond this position. At the time of the reverse rotation, the midpoint potential SV1 changes symmetrically with that before the reverse rotation. In this case, the midpoint potential SV1 remains in a region not exceeding the hysteresis upper limit value VH, and during this period, the direction of increase / decrease is reversed three times. Also,
Since the midpoint potential SV1 does not exceed the hysteresis upper limit value VH, the output SV2 of the comparator 5 is held at the “H” state.

In the sensor circuit 2, the midpoint potential SV1 between the MR elements 4a, 4a is also input to the phase shifter 6, and after the phase shifter 6 performs a phase difference setting process,
The output signal SV from the CR delay circuits 6c and 6d of the phase shifter 6
3, SV4 (electric signal). Output signal S
V3 and SV4 are generated at the same amplification factor as voltage signals having the same waveform, and the output signal SV3
The phase delay with respect to V1 is extremely small, and the output signal SV4
Has a predetermined phase delay with respect to the output signal SV3. These output signals SV3 and SV4 are input to an inverting input terminal and a non-inverting input terminal of the comparator 7, respectively.

The level of the output signal SV5 (detection result of the increase / decrease direction detecting means) of the comparator 7 changes from "H" to "L" when the value of the output signal SV3 is larger than the value of the output signal SV4. The value of the signal SV3 is the output signal SV4
Changes from "L" to "H" when the value is smaller than the value of.
Here, that the value of the output signal SV3 is larger than the value of the output signal SV4 indicates that the midpoint potential SV1 is increasing (rising), and conversely, the midpoint potential SV1 is decreasing (falling).
Therefore, the change in the level of the output signal SV5 detects the inversion in the increase / decrease direction of the midpoint potential SV1. This output signal SV5 is output from the inverter 1 of the detection circuit 3.
3 and the D-flip flop 11 are sent to the clock terminals. Also, the output SV2 of the comparator 5 described above
Are the waveform shaping circuit 9 of the detection circuit 3 and the D-flip
The signals are sent to the D terminals of the flops 10 and 11.

On the other hand, in the detection circuit 3, the signal SV5 from the comparator 7 of the sensor circuit 2 is input to the clock terminal of the D-flip-flop 10. The output SV2 of the comparator 5 described above is input to the D terminal of the D-flip flop 10. When the signal SV5 input to the clock terminal changes from “L” to “H”, the D-flip flop 10 is input to the D terminal before the signal SV5 changes, in synchronization with the rise. When the signal SV2 is "H", the signal SV7 of "H" (the detection result of the inversion detecting means) is output from the Q terminal to the EX_OR 14, and when the signal SV2 is "L", the signal SV7 of "L" is output.
From the Q terminal to the EX_OR 14.

The signal SV5 becomes a signal SV6 inverted by the inverter 13, and the signal SV6 is
Input to the clock terminal of flip-flop 11; The output SV2 of the comparator 5 described above is input to the D terminal of the D-flip flop 11. When the signal SV6 input to the clock terminal changes from “L” to “H”, the D-flip flop 11 is input to the D terminal before the signal SV6 changes, in synchronization with the rising of the signal SV6. When the signal SV2 is "H", the signal SV8 of "H" is output.
EX_OR1 from the Q terminal
4 and when the signal SV2 is "L", the signal SV8 of "L" is output from the Q terminal to the EX_OR14.

The EX_OR 14 outputs an "L" signal SV9 when the levels of the signals SV7 and SV8 from the D-flip flops 10 and 11 are the same, and outputs an "H" signal otherwise.
Is output to the clock terminal of the D-flip-flop 12. In the D-flip flop 12,
Since the Q · BAR terminal is connected to the D terminal, the signal SV9 input to the clock terminal changes from “L” to “H”.
When the output of the Q terminal before the change of the signal SV9 is “H”, ie, Q · B
When the output of the AR terminal is “L”, the “L” signal SV
10 is output from the Q terminal to the microcomputer 15, and when the output level of the Q terminal is "L", the signal SV10 of "H" is
Output to the microcomputer 15 from the terminal. The microcomputer 15 detects that the gear rotor G is rotating forward when the signal SV10 is "L", and detects that the gear rotor G is rotating reversely when the signal SV10 is "H". That is, the signal S
V10 changes from “L” to “H” or from “H” to “L”
Is detected, it is detected that the gear rotor G has reversed.

The operation of the reverse rotation detecting device 1 configured as described above will be described with reference to the timing chart of FIG. As described above, the MR elements 4a, 4
5A, there is almost no phase difference between the midpoint potential SV1 and the output SV3 of the phase shifter 6. Therefore, in FIG.
3 and the waveform of the midpoint potential SV1 are common, and their operations will be described. First, when the midpoint potential SV1 falls below the lower limit value VL of the hysteresis of the comparator 5 (time t1) while the gear rotor G is rotating forward, the output signal SV2 of the comparator 5 changes from "L" to "H". Changes to Thereafter, the midpoint potential SV1 is inverted in the increasing direction. At the subsequent time t2, when the midpoint potential SV1 is inverted in a decreasing direction without exceeding the hysteresis upper limit value VH, the output signal SV2 is held at "H" without change, and immediately after this, the output signal SV5 of the comparator 7 is output. Changes from “L” to “H”.

As described above, the signal SV5 changes from "L" to "H".
, The D-flip flop 10 before the change
Since the input SV2 of the D terminal is “H”, the signal SV5
In synchronization with the rising edge of the output terminal, the output SV7 of the Q terminal becomes "L".
From “H” to “H”. At this time, since the output SV8 of the Q terminal of the D-flip flop 11 remains at “H” and does not change, the output SV9 of the EX_OR 14 changes from “H” to “L”.

Thereafter, the midpoint potential SV1 is again inverted in the increasing direction, and when it exceeds the hysteresis upper limit value VH at the subsequent time t3, the output signal SV2 changes from "L" to "H". At the subsequent time t4, the midpoint potential SV1 is inverted in the decreasing direction. Immediately after that, the output signal SV5 of the comparator 7 changes from "L" to "H". The output SV7 of the flop 10 changes from “H” to “L”. As described above, when the output SV7 changes from “H” to “L”, the output SV8 of the Q terminal of the D-flip flop 11 does not change to “H”, and the output SV9 of the EX_OR 14 changes to “L”.
From “H” to “H”. In synchronization with the rise of the output SV9, the output SV10 of the D-flip flop 12 changes from "L" to "H", whereby the microcomputer 15
Detects that the rotation direction of the gear rotor G has changed from forward rotation to reverse rotation.

Thereafter, when the midpoint potential SV1 exceeds the hysteresis upper limit value VH of the comparator 5 (at time t).
In 5), the output signal SV2 of the comparator 5 changes from “H” to “L”. Thereafter, when the midpoint potential SV1 reverses in the increasing direction, and at time t6, reverses in the increasing direction without falling below the lower limit value VL of the hysteresis, the output signal SV2 is maintained at "L". The output signal SV5 of the comparator 7 changes from “H” to “L”, and the output SV6 of the inverter 13 changes from “L” to “H”.
Changes to

As described above, the signal SV6 changes from "L" to "H".
D-flip-flop 11 before change
Is low, the output SV8 of the Q terminal changes from "H" to "L" in synchronization with the rise of the signal SV6. At this time, the output SV7 of the Q terminal of the D-flip flop 10 remains at “L” and does not change, so that the output SV9 of the EX_OR 14 changes from “H” to “L”.

Thereafter, when the midpoint potential SV1 reverses again in the increasing direction, and at time t7, falls below the lower limit value VL of the hysteresis, the output signal SV2 changes from "L" to "H". At the subsequent time t8, the midpoint potential SV1 is inverted in the increasing direction, and immediately thereafter, the output signal SV5 of the comparator 7 changes from “H” to “L”, and the output SV6 of the inverter 13 changes from “L” to “L”. H ”. Thus, when the signal SV6 changes from "L" to "H", the input SV2 of the D terminal of the D-flip flop 11 before the change is "H".
Changes from “L” to “H” in synchronization with the rise of the signal SV6. At this time, Q of the D-flip flop 10
Since the output SV7 of the terminal remains at “L” and does not change, EX
The output SV9 of _OR14 changes from "L" to "H".

In synchronism with the rise of the output SV9, D-
The output SV10 of the flip-flop 12 changes from “H” to “L”. Thereby, the microcomputer 15 detects that the rotation direction of the gear rotor G has changed from reverse rotation to normal rotation.

As described above, the reverse rotation detecting device 1 of the present embodiment
According to the above, when the rotation direction of the gear rotor G is reversed, the midpoint potential SV1 between the MR elements 4a, 4a is in a region not exceeding the hysteresis upper limit value VH or a lower limit value VH.
While in the area not less than L, the direction of increase / decrease is three times,
Invert. Therefore, two signals SV3 and SV3 having a predetermined phase difference generated by the phase shifter 6 from the midpoint potential SV1.
By comparing SV4 with the comparator 7, the midpoint potential S
Whether the value of V1 does not exceed the hysteresis upper limit value VH and the direction of increase or decrease is three times, or whether the value of V1 is less than the lower limit value VL of hysteresis is 3 or less.
By detecting whether the rotation has been reversed, it is possible to accurately detect whether the rotation direction of the gear rotor G is reversed, that is, whether the rotation direction of the axle is reversed.

Further, since the comparator 5 constitutes a Schmitt trigger circuit having hysteresis as described above, chattering of the output signal SV2 can be prevented, and the presence or absence of reversal of the rotation direction of the axle can be detected stably. . Further, the predetermined width of the hysteresis is set to the midpoint potential SV1.
By setting as large as possible between the maximum value and the minimum value of, the reversal of the rotational direction of the axle can be detected more appropriately.

Further, a magnet rotor such as a conventional reverse rotation detecting device is not required, and can be configured by simply adding a simple circuit to an existing detecting device having a gear rotor G, and there is no need to newly add a sensor. Also, unlike the conventional reverse rotation detection device using a plurality of magnetic detection sensors, the reverse rotation in the rotational direction of the axle can be detected only by using one magnetic detection sensor (sensor unit 4). As described above, the manufacturing cost can be reduced, the degree of freedom in the layout of the reverse rotation detecting device 1 can be increased, and the entire device can be configured to be compact.

In the above-described embodiment, the MR
The sensor circuit 2 for detecting the midpoint potential SV1 between the elements 4a and 4a and the detection circuit 3 for detecting the presence or absence of the reversal of the rotation direction of the gear rotor G are constituted by electric circuits. Reference numeral 3 is not limited to an electric circuit, and may be constituted by a microcomputer program. Further, by applying a positive feedback to the comparator 7 via a resistor, the comparator 7 has a hysteresis characteristic,
Hysteresis may be applied to the output SV5. In this way, chattering of the output SV5 of the comparator 7 can be prevented.

[0045]

As described above, according to the apparatus for detecting reverse rotation of a rotating body and the method for detecting reverse rotation of the present invention, the manufacturing cost can be reduced, the degree of freedom in layout can be increased, and a compact structure can be realized. .

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of a sensor circuit of a reverse rotation detecting device for a rotating body according to an embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating a schematic configuration of a detection circuit of the reverse rotation detection device.

FIGS. 3A and 3B are explanatory diagrams for explaining the operation of the sensor circuit when the gear rotor is rotating in one direction, and FIG.
(C) A timing chart showing changes in the midpoint potential SV1 and the output SV2 of the comparator with the rotation of the gear rotor.

FIGS. 4A and 4B are explanatory diagrams for explaining the operation of the sensor circuit when the gear rotor is reversed, and FIG. 4A is a diagram illustrating the positional relationship between the teeth of the gear rotor and the MR element, and FIGS. 6 is a timing chart showing changes in a point potential SV1 and an output SV2 of a comparator, respectively.

FIGS. 5A to 5H are timing charts showing the operation of the reverse rotation detecting device when the gear rotor rotates backward from normal rotation and then returns to normal rotation.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 reverse rotation detection device 4a MR element (magnetic detection means) 4b magnet (magnetic field generation means) 6 phase shifter (signal generation means) 7 comparator (increase / decrease direction detection means) 10 D-flip flop (inversion detection means) 11 D-flip・ Flop (inversion detection means) 12 D-flip flop (reverse rotation detection means) 14 EX_OR14 (reverse rotation detection means) 15 Microcomputer (reverse rotation detection means) G Gear rotor (gear) Ga Gear rotor teeth SV1 Midpoint potential (detection signal) SV3 Output signal (electric signal) of phase shifter SV4 Output signal (electric signal) of phase shifter SV5 Output signal of comparator (detection result of increase / decrease direction detection means) SV7 Output signal of D-flip flop 10 (detection of inversion detection means) Result) SV8 D-flip-flop 11 output signal (inversion detection signal) Detection Result) VH upper limit value VL lower limit of the hysteresis Hysteresis

Claims (4)

[Claims] An apparatus for detecting reverse rotation of a rotating body for detecting the presence or absence of a reverse rotation in the rotating direction of the rotating body, comprising a magnetic body, rotating with the rotation of the rotating body,
A rotatable gear having a plurality of teeth arranged at intervals along the rotation direction on the outer peripheral surface; a magnetic field generating means for generating a magnetic field between the teeth of the gear; and a rotation of the gear. Magnetic detection means for outputting a detection signal representing the accompanying change in the magnetic field; signal generation means for generating two electric signals having a predetermined phase difference between each other based on the detection signal of the magnetic detection means; An increasing / decreasing direction detecting means for detecting an increasing / decreasing direction of the detection signal by comparing these two electric signals; an area in which the detection signal exceeds a reference value based on a detection result of the increasing / decreasing direction detecting means; An inversion detecting means for detecting whether or not the direction of increase or decrease of the detection signal has been inverted a plurality of times while staying in one of the areas less than And reversing detecting means for detecting the presence or absence of reversal of direction, the reverse rotation detecting device for a rotary body, characterized in that it comprises a. 2. The apparatus according to claim 1, wherein the reference value has a predetermined width of hysteresis. 3. A method for detecting reversal of a rotating body for detecting the presence or absence of reversal of the rotating direction of the rotating body, comprising: a plurality of magnetic bodies which are arranged on an outer peripheral surface of the rotating body at intervals along the rotating direction. A gear that is rotatable with the rotation of the rotating body, generates a magnetic field between the gear and the teeth, and outputs a detection signal indicating a change in the magnetic field with the rotation of the gear. Detecting, based on the detected detection signal, generating two electric signals having a predetermined phase difference between each other, by comparing these two electric signals, to detect the increase or decrease direction of the detection signal, Based on the detected detection signal increase / decrease direction, whether the detection signal increase / decrease direction is inverted multiple times while the detection signal stays in one of the region above the reference value and the region below the reference value. Before the detection Based on the presence or absence of multiple inversion of increase or decrease in the detected signal direction, reverse method for detecting rotary body and detecting the presence or absence of reversal of the rotational direction of the rotating body. 4. The method according to claim 3, wherein the reference value has a predetermined width of hysteresis.