JPH03295468A - Rotary sensor - Google Patents

Abstract

PURPOSE:To easily and speedily diagnose faults of a sensor part and a detecting circuit attached to the sensor part by providing a coil part nearby the sensor part and connecting it to a test signal source. CONSTITUTION:The sensor part 2 of the rotary sensor 1 is constituted by interposing a magneto-resistance element 5 between a core material 3 which is a magnetic body and a permanent magnet 4. The outer periphery of the core material 3 is wound with a coil 7, which has a DC power source 8a, an ON-OFF switch 8b, and a current adjusting means 8C; and a test signal source 8 is connected. Thus, the coil 7 is provided nearby the sensor part 2, so when faults of the sensor part 2 and the detecting circuit attached to it are diagnosed, it is not required to rotate the rotary member at the stop of a vehicle. Then the labor and time required for the operation are reduced and shortened and the fault diagnosis can be performed easily and speedily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotation sensor, and more particularly, to a rotation sensor in relation to a magnetic flux generated by a magnet. Various proposals have been made for rotation sensors for detecting the rotational speed of wheels, etc., and for example, Japanese Patent Laid-Open No. 5636054 discloses a configuration of a rotation sensor using a magnetoresistive element. ing. This rotation sensor is equipped with a rotor (rotating member), which has a plurality of teeth formed at equal intervals around its outer periphery, attached to a rotating shaft (rotating body) such as a wheel, axle, or propeller shaft. A detector (sensor section) having a core material made of a magnetic material and a permanent magnet on the other side is arranged so that the tip of the core material faces the teeth of the rotor. According to this, each time a tooth passes near the tip of the core material as the rotor rotates,
Since the magnetic flux density passing through the magnetoresistive element changes, the rotational speed of the rotating shaft is detected by extracting the resistance change corresponding to the change as an electric signal.

Further, as another example, for example, according to Japanese Utility Model Application Publication No. 1-120664, j- is arranged so as to face the tooth tip of a rotor (gear in the publication) that rotates in conjunction with a rotating shaft, as in the case of J-. In a detector (sensor section) having a core material and a permanent magnet placed behind the core material, a rotation sensor configuration is disclosed in which a coil is wound around the outer periphery of the core material. . According to this, an induced electromotive force is generated in the coil as the rotor rotates, and the rotational speed of the rotating shaft is detected by extracting the change in this induced electromotive force as the output 17.

[Problem to be solved by the invention]

By the way, the rotation sensor disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 56-36054 is mainly used for railway vehicles, but it is difficult to judge whether the magnetoresistive element, which is a component of this sensor, is broken or damaged. However, there is a problem in that it requires a great deal of effort and time, as testing must be carried out by actually running a ten-ryo vehicle and driving the rotating shaft to rotate. In addition, since one rotation sensor is attached to each rotating shaft in the railway vehicle, it is not only an extremely complicated task to test each magnetoresistive element one by one; Even when testing only the magnetoresistive elements, the entire long train must be run, and the waste of labor and time becomes even more significant. Furthermore, the same problem as above occurs when determining whether the operating state is normal or abnormal with respect to the electric circuit (detection circuit) that converts the resistance change of the magnetoresistive element into an electric signal to obtain the required output. .

On the other hand, the rotation sensor disclosed in the above-mentioned Japanese Utility Model Application Publication No. 1-120664 is mainly used in automobiles, and is used to diagnose failures of the coil that is a component of this sensor, and to convert the induced electromotive force generated in the coil into a required output. Even when diagnosing the failure of the electric circuit (detection circuit) for converting the
Although the smaller size of the vehicle may save some effort and time, it presents essentially the same problems as above.

The present invention has been made in view of the above circumstances, and it is possible to easily and easily diagnose the failure of sensor sections such as magnetic resistance elements and coils, and the accompanying detection circuits, without actually running the vehicle. The technical problem is to provide a rotation sensor that can be used quickly.

[Means to solve the problem]

The means to achieve the above technical challenges are as follows:
A rotating member that rotates in conjunction with a rotating body, a sensor unit that is disposed opposite to the rotating member, and a magnet that is provided on either the rotating member or the sensor unit and that creates magnetic flux between the two. , a rotation sensor including a detection circuit that detects the rotational speed of the rotating body based on a change in magnetic flux density that occurs as the rotating member rotates, the rotation sensor being connected to a test signal source at a position near the sensor section. It is located where the coil section is installed.

[Effect]

According to the above means, when no current flows from the test signal source to the coil section, magnetic flux is generated between the sensor section and the rotating member by the action of only the magnet (permanent magnet). The magnetic flux density of the magnetic flux changes as the rotor (or a rotor in which N and S poles of magnets are arranged alternately on the outer periphery) rotates in conjunction with the rotating body, and this change is transmitted to the detection circuit. The rotational speed of the rotating body is detected by the following steps.

On the other hand, when the vehicle is stopped, that is, when the rotating body is in a stopped state, if a current is passed from the test signal source to the coil part, a magnetic flux corresponding to this current value will flow between the rotating member and the sensor part. This occurs, and an electric signal corresponding to this magnetic flux is generated in the detection circuit. In this case, if the current flowing through the coil section is increased or decreased, the above-mentioned signal can be detected if the sensor section is operating normally. The electrical signal generated by the detection circuit passes the threshold level set in the detection circuit and increases or decreases, and by detecting this, it is possible to know the normal state of the sensor unit. becomes.

On the other hand, if the sensor section is malfunctioning, even if the value of the current flowing through the coil section is changed, the electrical signal generated by the detection circuit will not change by the required amount; does not increase or decrease with respect to the threshold level, and by detecting this, the abnormal state can be known.

Note that by performing the above operations, it is possible to simultaneously confirm whether the detection circuit is normal or abnormal.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

As shown in FIG. 1, the sensor section 2 of the rotation sensor 1 according to the present invention has a magnetic resistance element 5 interposed between a core material 3 made of a magnetic material and a permanent magnet 4. The tip of the material 3 is arranged to face teeth 6a of a gear 6 (rotating member; made of a magnetic material) that rotates in conjunction with a rotating body such as a wheel. There is a symbol B between the permanent magnet 4 and the gear 6.
, B are generated. A coil 7 is wound around the outer periphery of the core material 3, and this coil 7 includes:
A test signal source 8 having a DC power supply 8a, an on/off switch 8b, and current value adjusting means 8c (variable resistor, etc.) is connected. The test signal source 8 is not limited to a configuration in which the current value can be adjusted as shown in the figure, but various variations are possible, such as adopting a configuration in which the direction of the flowing current can be changed.

The magnetoresistive element 5 includes two resistors R whose resistance value changes depending on the magnitude of magnetic flux density, as shown in FIG.
51, RS2 is incorporated. Further, as shown in the figure, the detection circuit 10 that extracts the required output from the magnetoresistive element 5 consists of two resistors R1 and R2 connected in parallel to the resistors RS, , and R52, and this resistor. R1,
A differential amplifier 11 that amplifies the difference voltage between the voltage 2 at the connection point of R2 and the output voltage V1 of the magnetoresistive element 5, a waveform shaping circuit 12 having a threshold level Vs, and an output circuit 13 made of a transistor. Consisting of

In this case, when the magnetic flux density G is 0 Gauss, the output voltage 1 of the magnetoresistive element 5 becomes the set value, and the resistor R1,
The voltage 2 at the connection point of R2 is adjusted so that, for example, v2 = v1. As the magnetic flux density G gradually increases from 0 Gauss, the resistance value of the resistor R81 decreases, and as a result, as shown in FIG. ■Since the output voltage V3 from the differential amplifier 11 is higher than the magnetic flux density G
It gradually increases from 0 as . Further, the output voltage V from the waveform shaping circuit 12 becomes H level when VB<Vs with respect to the threshold level Vs,
When V3≧Vs, it becomes L level.

Therefore, as the gear 6 rotates, the sensor section 2
When the teeth 6a of the gear 6 are closest to the core material 3 (the state shown in FIG. 1), the magnetic flux density G passing through the magnetoresistive element 5 becomes the maximum value, and When the valleys of the teeth 6 face each other (the state shown in Fig. 3), the magnetic flux density G
Since each output voltage v1. is the minimum value, each output voltage v1. v3. The characteristics of v+ are as shown in FIG.

Therefore, when the gear 6 is in a stopped state (the vehicle is in a stopped state) and the trough of the gear 6 and the core material 3 are in a state facing each other, when no current is flowing through the coil 7, The magnetic flux φ1 shown in FIG. 6 is generated by the action of the permanent magnet 4 alone, and the magnetic flux density B1 is generated in the magnetic resistance element 5. In this case, as described above, the trough of the gear 6 and the core material 3 are facing each other, the magnetic flux φ1 and the magnetic flux density B1 have the lowest values. Under such conditions, if a current I is passed through the coil 7, a magnetic flux φa will be generated by the coil 7. Therefore, between the sensor section 2 and the gear 6, this magnetic flux φa and the magnetic flux φt A composite magnetic flux φX=φ1+φa is generated, and a composite magnetic flux density BX=KXφX is generated in the magnetoresistive element 5 (K: constant of proportionality). In this case, if the test signal source 8 is configured to be able to perform not only variable control of the current value but also variable control of the direction in which the current flows using known techniques, the magnitude and direction of the current 1 flowing through the coil 7 can be changed. By doing so, the composite magnetic flux density Bx becomes the characteristic line shown in FIG. The level switches from the H level or the 17th level to the opposite level with the current value ■□ at the intersection as the boundary.

Furthermore, when the gear 6 is in a stopped state and the teeth 6a of the gear 6 and the core material 3 are in a state facing each other, the magnetic flux φ2 (
The magnetic flux density B2) and the composite magnetic flux φy (
The composite magnetic flux density By) has the characteristics shown in Figure 6,
Therefore, the output voltage V,'' from the waveform shaping circuit 12 changes from the H level or I level to the opposite level with the current value I2 as the boundary.

Even when the gear 6 is stopped at a position other than the two positions exemplified above, the waveform shaping circuit 12
The output voltage from the converter switches from H level or L level to the opposite level at a predetermined current value. In this way, it is necessary to check the switching of the level of the output voltage from the waveform shaping circuit 12.
It can be known that the detection circuit 10 and the detection circuit 10 are operating normally, and if these are out of order, no change in level will occur in the output voltage from the waveform shaping circuit 12.

Next, a second embodiment of the present invention will be described.

In this second embodiment, the power source 8a of the test signal source 8 shown in FIG. 1 is an AC power source (its illustration is omitted). If the amplitude and frequency of the AC waveform A in the AC power source are appropriately set as shown in FIG. The magnetic flux (magnetic flux density) when no current is flowing is φL (B1) in the figure, and the composite magnetic flux (composite magnetic flux density) when current is flowing through the coil 7 is φx in the figure.
(Bx) The output voltage from the waveform shaping circuit 12 becomes H level with the current value 1 at the intersection of the magnetic flux density Bs corresponding to the threshold level Vs and the composite magnetic flux density Bx as the boundary. Or it switches from L level to reverse level.

Furthermore, when the teeth 6a of the gear 6 and the core material 3 are in a state where they are opposed to each other, the magnetic flux (magnetic flux density) and the composite magnetic flux (
The composite magnetic flux density) is φ2 (B2) and φ shown in the same figure, respectively.
y (By), and the output voltage V from the waveform shaping circuit 12
+' switches from the H level or L level to the opposite level with the current value I2 as the boundary.

In the first and second embodiments described above, the dimensions and arrangement position of the coil 7 are not limited to those shown in FIG. 1; for example, in FIG. Variations shown in c) and (d) are possible.

FIG. 9 shows a third embodiment of the present invention, in which the core material is divided into two core material pieces 31 and 32, and the core material pieces 3. ,3
Two magnetoresistive elements 51 and 52 are placed between 2 and the permanent magnet 4.
In the configuration in which each core material piece 3. ．． Coils 71 and 72 are wound around the outer periphery of the coils 71 and 72, respectively, and both coils 7
A test signal source 81.8z (a DC power supply may be used) is connected to each of the terminals 1.72 and 1.72. As shown in FIG. 10, each of the magnetoresistive elements 51 (52) has two resistors R3L, R32 (R53,
RS+), and its detection circuit IO includes a differential amplifier 11 that amplifies the difference voltage ■ between the output voltage ■1 of one magnetoresistive element 51 and the output voltage ■2 of the other magnetoresistive element 52. , a differential amplifier 1 with a threshold level
1, and an output circuit 13 that takes out the output voltage V of the waveform shaping circuit 12. Each output voltage v, V3 . The relationship between V and Gin is as shown in the time chart of Fig. 11, which means that the tooth 6a of the gear 6 shifts from the state shown in Fig. 12 (al) to the state shown in the same figure (bl, tc). A time chart between
FIG. 12(a) shows the time chart at time a and FIG. 12(b)
) corresponds to time point b, and in the figure (C1 corresponds to time point C. Therefore, with the configuration of the detection circuit 10 as described above, under the state shown in FIG. 12(b), V3
is O, so if one coil is wound around both the outer peripheries of the core pieces 31 and 32, it is not possible to perform the fault diagnosis as in the above-mentioned embodiment, but in this third embodiment, Since the two coils 7□ and 72 are wound separately, the above implementation can be carried out by passing current through only one of the coils, or by passing current through both coils in different directions. Failure diagnosis of the sensor section 2 and the detection circuit 10 can be performed in the same manner as in the example.

FIG. 13 shows a fourth embodiment of the present invention, in which a rotation sensor 1 includes a permanent magnet 4, a core material 3, and an induction coil 20 that induces a voltage due to changes in magnetic flux. A coil 7 is wound around the outer circumference of the coil 7.
A test signal source 8 is connected to the test signal source 8. The rotation sensor 1 is often used in automobiles, and the detection circuit is well known, so illustration and explanation thereof will be omitted.

According to this fourth embodiment, by extracting the voltage induced by passing a current through the coil 7 in the detection circuit of the induction coil 20, it is possible to diagnose the failure of the induction coil 20 and the detection circuit. .

In this embodiment, an alternating current is used as the test signal source 8, but a direct current signal may be used. In this case, the direct current may be a ramp signal or a pulse signal.

FIG. 14 shows a fifth embodiment of the present invention, in which a rotation sensor 1 having a configuration similar to that of the fourth embodiment is provided with terminals X1. An intermediate tap X9 is provided between X2, and a coil 7 connected to a test signal source 8 is connected between xl and X9.

Therefore, in this fifth embodiment as well, failure diagnosis can be performed in the same manner as in the fourth embodiment.

FIG. 15 shows a sixth embodiment of the present invention, in which the core material 3
In a configuration including a sensor section 2 consisting of a Hall element 21 and a sensor section 2, and in which N and S poles of a permanent magnet 22 are alternately arranged on the outer periphery of a rotating member 6 facing the sensor section 2, the core material 3 is A coil 7 is wound around the outer periphery, and a test signal source 8 (which may be a DC power source) is connected to the coil 7.

The detection circuit connected to the Hall element 21 is
For example, the configuration is substantially the same as that of the detection circuit 10 shown in FIG. 2 above. Therefore, in this sixth embodiment as well, the same effects as in the first embodiment (or second embodiment) can be obtained.

〔Effect of the invention〕

As described above, according to the rotation sensor according to the present invention, since the coil section connected to the test signal source is provided in the vicinity of the sensor section disposed opposite to the rotating member, the coil section connected to the test signal source This means that fault diagnosis of the detection circuit can be performed without rotating rotating parts when the vehicle is stopped, making the work much easier compared to the conventional case where fault diagnosis was performed by actually driving the vehicle. The advantage is that the effort and time required for the process is significantly reduced.

[Brief explanation of the drawing]

1 to 6 show a first embodiment of the present invention,
Fig. 1 is a schematic diagram showing the overall configuration of the rotation sensor, Fig. 2 is a schematic diagram showing the detection circuit, Fig. 3 is a schematic diagram of main parts showing the positional relationship between the rotating member and the sensor section, and Fig. 4 is A graph showing the relationship between magnetic flux density and voltage. Figure 5 is a graph showing the characteristics of magnetic flux density and each output voltage over time. Figure 6 is a graph showing the characteristics of magnetic flux with respect to changes in current and the corresponding characteristics of the output voltage. This is a graph showing. FIG. 7 is a graph showing magnetic flux characteristics and corresponding output voltage characteristics with respect to changes in current in the second embodiment of the present invention. FIG. 8 is a schematic view of the main parts showing another arrangement position of the coil portion in the first embodiment and the second embodiment. 9 to 12 show a third embodiment of the present invention, in which FIG. 9 is a schematic diagram showing the overall configuration of a rotation sensor, FIG. 1θ is a schematic configuration diagram showing a detection circuit, and FIG. Graphs showing the characteristics of each output voltage over time, Figure 12 (a), (b), (C
) is a schematic diagram of main parts showing the positional relationship between the rotating member and the sensor section, respectively. FIG. 13 is a schematic diagram showing the overall configuration of a rotation sensor in a fourth embodiment of the present invention. FIG. 14 is a schematic diagram showing the main part configuration of a rotation sensor in a fifth embodiment of the present invention. FIG. 15 is a schematic diagram showing the overall configuration of a rotation sensor in a sixth embodiment of the present invention. 1... Rotation sensor 2... Sensor part 4... Magnet (permanent magnet) 6... Rotating member (gear) 7... Coil part (coil) 8... Test signal source 8a... Power supply IO...Detection circuit B...Magnetic flux

Claims (1)

[Claims] (1) A rotating member that rotates in conjunction with a rotating body, a sensor unit that is disposed opposite to the rotating member, and a magnetic flux that is provided on either the rotating member or the sensor unit and generates magnetic flux between the two. In the rotation sensor, the rotation sensor includes a magnet that causes the rotating member to rotate, and a detection circuit that detects the rotational speed of the rotating body based on a change in magnetic flux density that occurs as the rotating member rotates. A rotation sensor characterized by having a coil portion to be connected.