JPH06289037A - Failure detection for rotation sensor - Google Patents

Abstract

PURPOSE:To detect the disconnection of each wire and short circuit failure between wirings in the case a sensing part and signal processing part are connected with power lines, signal lines and ground lines. CONSTITUTION:A first resistor R1 to a third resistor R3 are put in or near a signal processing part 40 and a fourth resistor R4 is put in or near a sensing part 30. By monitoring the voltages V1 and V2 of the first resistor R1 and the second resistor R2, respectively, existence of failure is judged based on the voltages V1 and V2. By this, regardless of rotating or stopping of a rotational body, the existence and kind of failure is surely detected by monitoring the voltages V1 and V2 of the signal processor 40 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a failure of a rotation sensor used for detecting a wheel speed of a vehicle.

[0002]

2. Description of the Related Art Conventionally, a so-called anti-lock braking system has been mounted on a vehicle and used in order to prevent the wheels from being locked during a braking operation. The antilock brake system detects the wheel speed, which is the rotation speed of each wheel. Then, the frictional state between each wheel and the road surface is determined based on the wheel speed of each wheel, and the brake pressure of each wheel is controlled based on the determination result.

To detect the wheel speed, a rotation sensor is used which detects the rotation of the rotor to which the rotation of the axle is transmitted. Conventionally, as a rotation sensor, one having a configuration in which an electromagnetic detector having a permanent magnet and a voltage generating coil is opposed to a gear-shaped rotor having periodic irregularities formed on its peripheral portion is widely used. Recently, for example, Hall I
Semiconductor type sensing devices such as C have also been used. A semiconductor type sensing device has higher sensitivity than an electromagnetic detector and can detect over a wide speed range.

FIG. 7 is a block diagram showing the electrical construction for detecting the wheel speed using the Hall IC. Hall i
C10 is arranged in the vicinity of the rotor (not shown), and detects the fluctuation of the magnetic field generated by the rotation of the rotor. Incidentally, C ₁₀ is a capacitor for removing a noise component caused by vibration of the vehicle body. Hall IC
The sensing unit 11 including 10 and the like is connected to the signal processing unit 12 that is several meters away by the wire harness 5. In this signal processing unit 12, antilock
A microcomputer 13 is provided as a control center of the brake system.

The hall harness 10 is attached to the wire harness 5.
Includes a power supply line 1 for supplying a power supply voltage Vcc (for example, 12 V) to the signal line 2, a signal line 2 for transmitting the output signal of the Hall IC 10 to the signal processing unit 12, and a ground line 3 for giving a ground potential. Has been. Some semiconductor-type sensing devices have a space between the sensing unit and the signal processing unit.
Although some can be connected by a wire system, it is disadvantageous from the viewpoint of noise immunity and the degree of freedom in designing a power supply, and in general, the three-wire system as shown in FIG. 7 is used. Recommended.

In the signal processing section 12, the power supply line 1 is connected to the terminal t1.
, The signal line 2 is connected to the terminal t2, and the ground line 3 is connected to the terminal t3. The power supply voltage Vcc is supplied to the line 14 connected to the terminal t1, and the resistor R ₁₀ is interposed between the line 14 and the line 15 connected to the terminal t2. The signal appearing on the line 15 is adjusted in level by the buffer circuit 16 and then input to the input port P ₁₁ of the microcomputer 13.

The Hall IC 10 changes the magnitude of the current flowing from the signal line 2 to the inside according to the fluctuation of the magnetic field accompanying the rotation of the rotor. This fluctuation of the current appears as a fluctuation of the voltage drop in the resistor R _{10, and} as a result, the voltage of the signal line 2 changes. Therefore, the cycle of the pulse signal output from the buffer circuit 16 corresponds to the rotation speed of the rotor, that is, the wheel speed. Therefore, the microcomputer 13 can know the wheel speed by counting the number of output pulses of the buffer circuit 16 within a fixed time or detecting the pulse width of the output pulse of the buffer circuit 16.

By the way, since the antilock brake system prevents the wheels from being locked by attenuating the brake pressure, if a signal corresponding to the wheel speed is not input to the microcomputer 13, a failure occurs. If so, the brake pressure will not be properly controlled. For example, the sensing unit 11 and the signal processing unit 12
If a disconnection occurs in any of the power supply line 1, the signal line 2 and the ground line 3 or a short circuit occurs between the lines, a pulse signal corresponding to the wheel speed is input to the microcomputer 13. Will not be done. In this case, the microcomputer 13 erroneously recognizes that the wheels are locked and attenuates the brake pressure. Therefore, when the brake pedal is operated, a sufficient brake pressure may not be obtained.

In order to solve this problem, a disconnection failure or a short circuit failure of the wiring between the sensing section 11 and the signal processing section 12 is detected, and when these failures are detected, the antilock control by the microcomputer 13 is performed. It is necessary to cancel. FIG. 7 shows one technique for detecting the above-mentioned disconnection failure and short-circuit failure. That is, the signal from the terminal t2 is input to the analog / digital (A / D) converter 18 through the smoothing circuit 17, and the output of this A / D converter 18 is input to the microcomputer 13
Is input to the input port P ₁₂ .

When none of the failures occurs, the power supply voltage Vcc and the ground potential alternately appear at the terminal t2 as the wheels rotate. Therefore, the output voltage of the smoothing circuit 17 becomes approximately Vcc / 2, and the data corresponding to this voltage is input to the microcomputer 13. on the other hand,
When the power supply line 1 breaks, the signal line 2 breaks, the ground line 3 breaks, and a short circuit occurs between the power supply line 1 and the signal line 2, the potential of the terminal t2 is fixed to the power supply voltage Vcc. In addition, when a short circuit occurs between the signal line 2 and the ground line 3 and a short circuit occurs between the power line 1 and the ground line 3, the potential of the terminal t2 is fixed to the ground potential.

As described above, when any failure occurs, the output of the smoothing circuit 17 becomes the power supply voltage Vcc or the ground potential, and takes a value different from the voltage Vcc / 2 in the normal state. Therefore, in the microcomputer 13, A /
A failure can be detected by monitoring the output data of the D converter 18.

[0012]

However, in the above-mentioned technique, although the failure can be detected when the wheels are rotating, the failure cannot be detected when the wheels are not rotating. There is. This will be described in detail below. The Hall IC 10 is a sensor that detects the strength of the surrounding magnetic field, rather than the fluctuation of the magnetic field. Therefore, for example, Hall I
When C10 and the tooth portion (projection portion) of the gear-shaped rotor face each other, the output of the Hall IC 10 is at a high level (for example, V
cc = 12V), and when the Hall IC 10 faces the groove (recess) of the rotor, the output of the Hall IC 10 becomes low level (for example, 0.1V).

Therefore, if the Hall IC 10 faces the teeth or grooves of the rotor when the rotation of the wheels stops and the rotor stops, the output of the Hall IC 10 is fixed at high level or low level, respectively. become. That is, since the voltage of the terminal t2 is fixed to the high level or the low level, the output of the smoothing circuit 17 is 12V.
Or, it becomes 0.1V. Therefore, the data input from the A / D converter 18 to the input port P ₁₂ of the microcomputer 13 is almost the same as the data at the time of the above-mentioned failure occurrence.

Table 1 below shows that the terminal t
The voltage appearing at 2 is shown for the case of normal operation and the failure occurrence of each mode. In Table 1, "when stopped in a high state" means that the rotor stops while the output of the Hall IC 10 is at a high level, and "when stopped at a low state" means that the output of the Hall IC 10 is at a low level. Shows the case where the rotor stops. The unit of the numerical value is V
(Bolt).

[0015]

[Table 1]

As can be seen from Table 1, even in the normal state, the voltage of the terminal t2 is 12V when the high state is stopped, and the voltage of the terminal t2 is 0.1V which is a value near 0V when the low state is stopped. . Therefore, in the above-described technique of detecting a failure by monitoring whether the output of the smoothing circuit 17 has a value near Vcc / 2, there is a possibility that the failure cannot be detected when the rotor is stopped.

Not only that, as is apparent from Table 1, the voltage at the terminal t2 is the same when the "high state is stopped" or when the failure is normal and when the failure occurs. Therefore, it is impossible to detect the failure based on the voltage of the terminal t2. Further, when the “low state is stopped”, and with respect to the failure of and, the voltage appearing at the terminal t2 does not change much between the normal time and the failure time, and thus it is difficult to detect the presence or absence of the failure.

Therefore, an object of the present invention is to solve the above-mentioned technical problems and to provide a failure detecting device for a rotation sensor capable of surely detecting a failure even when the rotation is stopped.

[0019]

According to a first aspect of the present invention, there is provided a rotation sensor failure detection device which is on or near the power supply line or near the signal processing unit. A first resistor that is inserted in series at any position on the wiring from the signal processing unit to the power supply terminal in the signal processing unit, and in the vicinity of the signal processing unit or in the signal processing unit, on the signal line or from this signal line. A second resistor inserted in series at any position on the wiring reaching the input terminal in the signal processing unit, and in the vicinity of the signal processing unit or in the signal processing unit, from the first resistor to the inside of the signal processing unit. At any position on the wiring leading to the power supply terminal of
A third resistor connected in parallel between any of the positions on the wiring from the resistance of to the input terminal in the signal processing unit, and in the vicinity of the sensor or in the sensor, on the signal line or from this signal line. A fourth parallel connected between any position on the wiring reaching the output terminal in the sensor and any position on the ground line or on the wiring extending from the ground line to the ground terminal in the sensor. The resistors and the voltages V ₁ and V ₂ at the sensor-side ends of the first resistor and the second resistor are monitored, respectively, and the presence or absence of a failure is determined based on the changes in the voltages V ₁ and V _2. And a determining means.

According to another aspect of the present invention, there is provided a rotation sensor failure detecting device, wherein the determining means is means for detecting an average voltage of the voltages V ₁ and V _{2 and} a value at which the detected average voltage deviates from a predetermined range. And means for determining that a failure has occurred.

[0021]

[Function] Between the sensing unit and the signal processing unit, a power line,
In the configuration connected by the signal line and the ground line,
There is a possibility that a disconnection failure of each of these wirings or a short circuit failure between the wirings may occur. In the present invention, the first resistor to the fourth resistor
Even when the rotating body is stopped, the voltage that appears in the power supply line in a normal state and the voltage that is transmitted to the signal processing unit through the signal line and the signal processing unit when a failure occurs The voltage appearing on the power supply line and the signal line in the vicinity of can be made different. Therefore, the determination means monitors the voltages V ₁ and V ₂ of the power supply line and the signal line in the vicinity of the signal processing unit and determines the presence or absence of a failure based on the voltage.

The determination means may detect the average voltage of the power supply line and the signal line, and monitor whether the detected average voltage is a value deviating from a predetermined range. Even if the voltage of the signal line fluctuates while rotating, the influence of this voltage fluctuation can be eliminated to determine the presence or absence of a failure.

[0023]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a failure detection device for a rotation sensor according to an embodiment of the present invention.
This device is a Hall IC3 that detects the rotation of each wheel.
1 including a sensing unit 30 and a microcomputer 41 serving as a control center of the antilock brake system.
And a signal processing section 40 including. Sensing part 3
A wire harness 50 connects the 0 and the signal processing unit 40. The wiring length from the sensing unit 30 to the signal processing unit 40 is about several meters.

The sensing section 30 has a Hall IC 31 for detecting the strength of the surrounding magnetic field and a capacitor C1 for removing a noise component caused by vehicle vibration. The wire harness 50 includes a power supply line 51 for supplying the power supply voltage Vcc (for example, 12 V) from the signal processing unit 40 to the sensing unit 30, and a signal line for transmitting the output signal of the Hall IC 31 to the signal processing unit 40. 52 and a ground line 5 for applying a ground potential from the signal processing unit 40
3 and 3 are included. The power supply line 51 is connected to the power supply terminal 31b of the Hall IC 31, and the signal line 32 is connected to the hall I.
It is connected to the output terminal 31a of C31, and the ground wire 53 is connected to the ground terminal 31c of the Hall IC 31. In addition, the power supply line 51, the signal line 52, and the ground line 5
3 are terminals T1, T2, T of the signal processing unit 40, respectively.
Connected to 3. The power supply voltage Vcc is applied to the terminal T1 through the resistor R1, the ground potential is applied to the terminal T3, and the terminal T2 is connected to the buffer circuit 42 through the resistor R2.

The signal processing unit 40 includes the above-mentioned microcomputer 41, a resistor R1 connected between the terminal T1 and the power supply Vcc, a resistor R2 connected between the terminal T2 and the buffer circuit 42, and a power supply Vcc-buffer circuit. A resistor R3 connected between 42, a smoothing circuit 43a for smoothing the signal applied to the terminal T1, a smoothing circuit 43b for smoothing the signal applied to the terminal T2, and smoothing circuits 43a and 43b. A / D converter 4 for converting the output voltage of the
4a and 44b. The output signal of the buffer circuit 42 and the output signals of the A / D converters 44a and 44b are given to the input port of the microcomputer 41.

The smoothing circuits 43a and 43b are each composed of an integrating circuit including a resistor and a capacitor.
FIG. 2 is an illustrative view for explaining the principle of rotation detection by the Hall IC 31. The Hall IC 31 is arranged near the rotor 35 to which the rotation of the axle is transmitted. More specifically, the rotor 35 has teeth 35a periodically formed on the peripheral edge thereof, and rotates around the axis 36 as the axle rotates. The Hall IC 31 is arranged so as to face the peripheral portion of the rotor 35.
Behind 1 is a permanent magnet 37.

As for the gap g between the permanent magnet 37 and the rotor 35, as shown in FIG.
2 is small, but is large when the groove 35b between the teeth 35a is facing the Hall IC 31, as shown in FIG. 2 (b). The density of the magnetic flux passing through the Hall IC 31 changes depending on the size of the gap g. Hall IC
31 is a voltage corresponding to the surrounding magnetic flux density
Output to. Therefore, the rotor 35 and the Hall IC 31
If the positional relationship with is in the state of FIG. 2 (a), the output terminal 31
The potential of a becomes high level (≈Vcc), for example, and if the positional relationship between them is as shown in FIG. 2 (b), the output terminal 31a
Potential becomes low level (value close to ground potential, for example, 0.1 V). Therefore, when the rotor 35 rotates, a signal which changes its height between high and low appears at the output terminal 31a in a cycle corresponding to the rotation speed.

The change in the potential at the output terminal 31a appears at the terminal T2 as it is. Therefore, the buffer circuit 4
The output signal 2 is a pulse signal having a cycle corresponding to the rotation speed of the rotor 35. The microcomputer 41 can obtain the rotation speed of the rotor 35 by counting the number of output pulses of the buffer circuit 42 within a fixed time or measuring the pulse width of the output pulse.

The rotor 35 is made of a magnetic material such as iron or a material having a high magnetic permeability such as ferrite. Also,
Even if the material is normal copper or sintered alloy, the gap g
As long as it has a magnetic permeability that allows the magnetic flux density in the vicinity of the Hall IC 31 to be changed in accordance with the change of, it can be applied as a constituent material of the rotor 35.

Next, the sensing unit 30 and the signal processing unit 40
A process for detecting a failure related to the wiring between and will be described. The type of failure is practically sufficient considering the case of one wire disconnection or two wire short circuit. These failures are
All the cases are covered in 6 ways, which are shown in a simplified manner in FIGS. 3 and 4. Specifically, as shown in Figs. 3 (a), (b),
(c) shows power line 51, signal line 52, and ground line 5 respectively
3 shows a case where a disconnection failure occurs. Also, FIG.
(d) shows a case where a short-circuit fault occurs between the power supply line 51 and the signal line 52, and FIG. 4 (e) shows a case where a short-circuit fault occurs between the signal line 52 and the ground line 53. ) Indicates a case where a short-circuit failure occurs between the power supply line 51 and the ground line 53.

For example, assume that the power supply voltage Vcc is 12 V and the resistance values of the resistors R1, R2, R3 and R4 are as follows. R1 ・ ・ ・ ・ ・ ・ 300Ω R2 ・ ・ ・ ・ ・ ・ 300Ω R3 ・ ・ ・ ・ ・ ・ 1.1kΩ R4 ・ ・ ・ ・ ・ ・ 10kΩ When the vehicle stops and the rotation of the rotor 35 stops, the voltage V ₁ appearing at the terminal T1 and the voltage V ₂ appearing at the terminal T2 are the same as in the normal state, as shown in FIGS. 3 (a) to 3 (c) and FIG. 4 (d). It is shown in comparison with the failure occurrence time of each mode shown in (f). In Table 2, "when stopped in a high state" indicates that the rotor 35 is stopped while the output of the Hall IC 31 is at a high level, and "when stopped in a low state" is when the output of the Hall IC 31 is at a low level. The case where the rotor 35 is stopped in this state is shown. The unit of the numerical value is V (volt).

[0032]

[Table 2]

In a normal state where no failure occurs, if the output of the Hall IC 31 is at a high level, the power line 51 has a current of about 7 m for driving the Hall IC 31.
A flows. Therefore, the voltage of the terminal T1 (that is, the power supply voltage supplied to the Hall IC 31) V ₁ has a constant value Vcc-7 mA × R1 = 9.9 [V] lower than Vcc due to the voltage drop due to the resistor R1. The voltage of the terminal T2 (that is, the voltage of the signal line 52 near the signal processing unit 40) V ₂ is Vcc × R4 / (R3 + R2 + R4) = 10.53 [V].

On the other hand, a normal operation with no failure
In this state, the output of Hall IC31 is low level (example
0.1V), the impedance of the output terminal 31a
Is lower than when stopped in the high state,
Voltage V of child T2₂Is almost at ground potential. According to the experiment
If this is the case, the voltage V ₂
Became about 0.1V. In addition, the voltage V of the terminal T1₁Is
Same as above, lower than Vcc due to resistance R1 voltage drop
It takes a constant value of 9.90V.

Next, disconnection failure of the power supply line 51 (see FIG. 3)
Corresponds to (a). ) Will be described. When the power supply line 51 is broken, the current for driving the Hall IC 31 does not flow. Therefore, the voltage V ₁ is approximately equal to the power supply voltage 12.00 in both the high state stop state and the low state stop state.
It becomes V. On the other hand, the voltage V ₂ becomes 10.53V divided by the resistors R3, R2, and R4.

Focusing on the voltage V ₁ , the voltage V ₁ is 12.
Since it is 00V, the normal value is 9.90 when stopped in the high state.
Different from V. Therefore, it is possible to detect the occurrence of a failure. Next, a disconnection failure of the signal line 52 (see FIG.
Corresponds to (b). ) Will be described. At this time,
Since the current for driving the Hall IC 31 flows, the voltage V ₁ is 9.90V, but since no current flows into the resistor R2, the voltage V ₂ becomes 12.00V, which is equal to the power supply voltage Vcc. Therefore, by paying attention to the change in the voltage V ₂ , it is possible to determine the abnormality.

When the disconnection failure of the ground wire 53 (corresponding to FIG. 3C) occurs in the case of, the Hall IC 3
Since the current for driving 1 does not flow, the voltage V ₁ becomes 12.00 V which is almost equal to the power supply voltage in both the high state stop state and the low state stop state. Further, since the ground line 53 is also disconnected, the voltage V ₂ becomes 12.00V which is almost equal to the power supply voltage Vcc. Therefore, the failure can be determined by paying attention to the change in the voltage V ₁ .

When a short circuit failure (corresponding to FIG. 4 (d)) between the power supply line 51 and the signal line 52 occurs, the Hall IC 31 is mainly connected to the resistor R1 when the high state is stopped. Resistor R3 + R2 combined resistance (written as R _x ) and resistance R
The voltage divided by 4 and 4 is applied. In the formula, V ₁ = V ₂ = Vcc × R4 / (R _x + R4) = 11.71
[V]. Therefore, the voltage becomes higher than that in the case where power is supplied during normal operation. Further, when stopped in the low state, the impedance of the output terminal 31a is lower than that in the stopped state in the high state, so that the voltages V ₁ and V ₂ are considerably low values. According to the experiment, although the value varies depending on the type of the Hall IC 31, the value is 2.0 to 2.5V.

In the following case, that is, the signal line 52 and
Short-circuit failure with the ground wire 53 (corresponding to Fig. 4 (e))
Occurs, the voltage V₂Naturally becomes 0V. But the electric
Pressure V ₁The current that drives the Hall IC 31 flows
Thus, it is 9.90V. Therefore, the voltage V₂Pay attention to
Then, the failure can be determined. If, ie, power
Short circuit between wire 51 and ground wire 53 (corresponding to Fig. 4 (f)
To do. ) Occurs, the voltage V₁Of course is 0V
It Voltage V₂Resistance R1, resistance R3, resistance R2, resistance
It becomes 0V through R4. Both are different from normal values
Take

In this way, in the event of any or all of the failures, the voltage V _{1 at} the terminal T1 and the terminal T1
Either or both of the voltages V ₂ of 1 and ₂ have a value different from the normal value. Therefore, in the microcomputer 31, based on the value given to the input port P2, the voltage V ₁ ,
Based on the value of V ₂ , the type of failure can be determined.

A concrete determination process is illustrated in FIG. As described above, in the present embodiment, it is possible to identify the failures from to whether the high state is stopped or the low state is stopped. On the other hand, as can be understood from the above-mentioned Table 1, in the conventional art, the failure from can be detected only when the low state is stopped, and therefore, the failure which cannot be sufficiently performed in the conventional technique or the failure detection is essential. It is possible in the embodiment.

However, the processing shown in FIG. 5 is an example, and more simply, the voltages V ₁ and V ₂ have normal values of 9.90 V and 1
It is monitored whether or not the value is within a predetermined range set in the vicinity of 0.53 V and 0.10 V, and normal when the voltages V ₁ and V ₂ are values within the predetermined range, and is outside the predetermined range. When it is detected that the value is taken, it may be determined that any failure has occurred.

After it is determined that a failure has occurred, the microcomputer 31 stops the antilock control. In this way, the microcomputer 3
In No. 1, not only when the vehicle is traveling, based on the voltage obtained by averaging the voltage of the terminal T2 by the smoothing circuit 43,
The failure can be reliably detected even when the vehicle is stopped. As a result, the safety of the anti-lock braking system can be significantly improved.

The voltage V when a short-circuit failure (corresponding to FIG. 4 (d)) between the power supply line 51 and the signal line 52 occurs.
Ground wire 5 when the value of ₁ and V ₂ is 11.71V
When the disconnection failure of _No. 3 (corresponding to FIG. 3 (c)) occurs, the voltage difference between the voltage V ₁ and the value of V ₂ of 12.00 V is 0.29.
Since it is V, which is relatively small, it is considered that this fault is the most difficult to detect. However, the practical resolution of the A / D converter used in the detection device is about 0.05V. Therefore, it is 0.29 in normal and in failure.
If there is a voltage difference of about V, it becomes larger than the resolution of the A / D converter as described above, and the microcomputer 31 can perform failure determination with sufficiently high accuracy. Also, this voltage difference is
The value of the resistor R4 should be made smaller, or the resistors R1 and R2 should be
It can be widened by increasing the value of. For example, R4 = 8 kΩ, R1 = 500Ω, R2 = 50
If it is set to 0Ω, it will drop from 11.71V to 11.45V. Therefore, for example, when the resolution of the A / D converter 44 is low, it is possible to deal with it by changing the resistance value. However, if the values of the resistors R1 and R2 are made too large, they become a heat source, and when the power supply voltage drops, the Hall IC
The voltage supplied to 31 may be insufficient.
If the value of the resistor R4 is made small, the amplitude of the signal cannot be made large, so it cannot be made too small.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the rotor to which the rotation of the axle is transmitted is shown in FIG.
It is also possible to apply a disk-shaped rotor 60 whose peripheral portion is alternately magnetized to have N poles and S poles, as shown in FIG. In this case, it is not necessary to arrange a permanent magnet behind the Hall IC 31.

Further, in the above embodiment, the signal processing unit 40
Although the resistors R1, R2 and R3 are provided inside, the resistors R1, R2 and R3 may be connected outside the signal processing unit 40 in the vicinity of the signal processing unit 40. That is, the resistor R1 and the resistor R2 are respectively the power line 51 or the signal line 52.
It may be inserted in the middle of. Furthermore, the resistor R4
Is any position on the signal path from the Hall IC 31 to the resistor R2 and the middle of the ground line 53 or the Hall IC.
It suffices if it is connected to the ground terminal 31c of 31.

Further, in the above embodiment, the case where the wheel speed is detected has been described as an example, but the present invention can be widely applied to the rotation sensor for detecting the rotation information such as the rotation speed and the rotation angle. Is something that can be done. In addition, various design changes can be made without changing the gist of the present invention.

[0048]

As described above, according to the present invention, even when the rotating body is stopped, the voltage transmitted to the signal processing unit via the signal line or the power supply line in the normal state and the failure. The voltage appearing on the signal line or the power line near the signal processing unit at the time of occurrence can be made different. Therefore, it is possible to reliably detect the presence or absence of a failure and the type of failure by monitoring the voltage of the signal line and the power supply line regardless of whether the rotating body is rotating or stopped.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a failure detection device for a rotation sensor according to an embodiment of the present invention.

FIG. 2 is an illustrative view for explaining the principle of rotation detection by a Hall IC.

FIG. 3 is an electric circuit diagram for explaining a failure mode, where (a) shows a disconnection failure of a power supply line, (b) shows a disconnection failure of a signal line, and (c) shows a disconnection of a ground line. Indicates a failure.

FIG. 4 is an electric circuit diagram for explaining a mode of failure, where (d) shows a short circuit failure between a power supply line and a signal line, (e) shows a short circuit failure between a signal line and a ground line, (f) shows a short-circuit fault between the power line and the ground line.

FIG. 5 is a flowchart illustrating a process of determining a failure type based on the values of the voltages V ₁ and V ₂ .

FIG. 6 is a block diagram showing a configuration for obtaining rotation information using a Hall IC.

FIG. 7 is a block diagram showing a configuration of a conventional failure detection device that detects a wheel speed using a Hall IC.

[Explanation of symbols]

 30 sensing unit 31 Hall IC 31a output terminal 31b power supply terminal 31c ground terminal 35 rotor 40 signal processing unit 41 microcomputer 42 buffer circuit 43a smoothing circuit 43b smoothing circuit 44a A / D converter 44b A / D converter 50 wire harness 51 power line 52 signal line 53 ground line 60 rotor R1 first resistance R2 second resistance R3 third resistance R4 fourth resistance

Claims (2)

[Claims] 1. A power supply line, a signal line, and a signal line between a sensor that outputs a signal corresponding to a change in a magnetic field near a rotating body and a signal processing unit that processes an output signal of the sensor to obtain rotation information. In a device connected by a ground line, in the vicinity of the signal processing unit or in the signal processing unit,
A first resistor serially inserted at any position on the power supply line or on a wiring from the power supply line to a power supply terminal in the signal processing unit, and in the vicinity of the signal processing unit or in the signal processing unit,
A second resistor inserted in series at any position on the signal line or on a wiring from the signal line to an input terminal in the signal processing unit, and in the vicinity of the signal processing unit or in the signal processing unit,
Between any position on the wiring from the first resistance to the power supply terminal in the signal processing unit and any position on the wiring from the second resistance to the input terminal in the signal processing unit in parallel. The third resistor connected, and in the vicinity of the sensor or in the sensor, any position on the signal line or on the wiring from the signal line to the output terminal in the sensor, and on the ground line or this ground line A fourth resistor connected in parallel with any position on the wiring reaching the ground terminal in the sensor, and voltages V ₁ and V at the sensor-side ends of the first resistor and the second resistor. ₂ are respectively monitored and their voltages V ₁ , V
_2. A failure detecting device for a rotation sensor, comprising: a determining unit that determines the presence or absence of a failure based on the change of ₂ . 2. The determining means determines the average voltage of the voltages V ₁ and V ₂ , and determines that a failure has occurred when the detected average voltage has a value deviating from a predetermined range. And a means.
Failure detection device for the rotation sensor described.