JP5205891B2 - Torque detection device - Google Patents

Description

  The present invention relates to a torque detection device that is used to detect a steering torque applied to a steering member for steering, for example, in an electric power steering device.

  In an electric power steering device that assists steering by driving a steering assist motor in response to a rotation operation of a steering member such as a steering wheel and transmitting the rotational force of the motor to a steering mechanism, the steering assist motor It is necessary to detect the steering torque applied to the steering member to be used for drive control. For this detection, a torque detection device constructed in the middle of the steering shaft that connects the steering member and the steering mechanism is conventionally used. ing.

  In this torque detection device, a steering shaft to be detected is divided into a first shaft and a second shaft that are coaxially connected by a thin torsion bar as a torsion spring, and the steering shaft is rotated by rotating the steering member. When a steering torque is applied, a relative angular displacement is generated between the first and second shafts with the torsion bar being twisted, and the steering torque is detected using the relative angular displacement as a medium.

  The relative angular displacement between the first and second axes has been conventionally detected by various means. One of them is a cylindrical magnet that rotates integrally with the first axis, and a magnetic yoke that rotates integrally with the second axis. There is a torque detection device that uses a change in the magnetic circuit between them (see, for example, Patent Document 1).

  The magnetic yoke that rotates integrally with the second shaft is a soft magnetic ring in which a plurality of magnetic pole claws extending in the axial direction are arranged on one side of an annular yoke body in the circumferential direction. Two pieces arranged alternately in the circumferential direction and arranged in the axial length direction are fixed to the second shaft as a set. The cylindrical magnet that rotates integrally with the first shaft is a multipolar magnet in which the same number of pairs of magnetic poles as the magnetic pole claws of the magnetic yoke are arranged in the circumferential direction, and relative angular displacement occurs in the first and second shafts. When there is no neutral state, the magnetic yoke is fixed to the first shaft in phase with the circumferential direction so that the magnetic pole claws of the magnetic yoke are aligned with the boundary between the N and S poles.

  On the outside of the two magnetic yokes, a magnetism collecting ring made of a soft magnetic material is arranged so as to face and oppose each yoke body. Each of these magnetism collecting rings is provided with a magnetism collecting portion that is connected to each other with a predetermined air gap therebetween, and a magnetic sensing element such as a Hall element is used in the air gap of these magnetism collecting portions. A magnetic sensor is arranged.

When a relative angular displacement occurs between the first axis and the second axis by the above configuration, a phase difference in the opposite direction occurs between the magnetic pole claws of the two magnetic yokes and the magnetic pole of the cylindrical magnet, The magnetic flux leaking into the air gap between the magnetic flux collectors of each magnetic flux collecting ring increases or decreases due to the magnetic flux change in each magnetic yoke according to this phase difference, and the output change of the magnetic sensor according to this increase and decrease The relative angular displacement between the first and second axes can be detected by extracting the torque, and the torque (steering torque) applied to the first and second axes can be obtained.
JP 2003-149062 A

  When the torque detection device configured as described above is applied to an electric power steering device, a countermeasure against failure is indispensable for eliminating the unstable steering assistance due to erroneous detection of the steering torque. Conventionally, as disclosed in Patent Document 1, two magnetic sensors are arranged on the circumference of the magnetism collecting ring, and fail judgment of each magnetic sensor is sequentially performed by comparing their outputs, Even when it is determined that the magnetic sensor is in a fail state, torque can be detected by the output of the other magnetic sensor so that steering assistance can be continued.

  However, the conventional anti-failure measures taken as described above cause a short circuit (power fault or ground fault) in the power supply line or the ground line of the two magnetic sensors, the power supply is cut off, and the output of both magnetic sensors. However, there is a problem that the steering assistance cannot be continued without any effect in the case where the two wheels simultaneously fail.

  In such a case, the above-described fail determination based on the output comparison of the two magnetic sensors is also uncertain, and there is a possibility that erroneous steering assistance based on the erroneous steering torque detection result is executed.

  The present invention has been made in view of such circumstances, and even when a short circuit occurs in the power supply line or the ground line, the outputs of the two magnetic sensors do not fail at the same time. An object of the present invention is to provide a torque detection device capable of detecting torque based on output.

A torque detector according to a first aspect of the present invention includes a cylindrical magnet that rotates integrally with one of the first and second shafts connected coaxially, a set of two magnetic yokes that rotate integrally with the other, and these A magnetic sensor for detecting a change in the magnetic flux of the magnetic yoke, and a torque detector for calculating torque applied to the first and second shafts based on the output of the magnetic sensor, comprising two of the magnetic sensors, the two magnetic sensors, each of the power supply line, connected to an external tare Ri by two sensor harnesses summarizing the ground line and signal lines to each other, the two sensor harness, each of the power supply line, ground line and collectively connecting portion between the signal line, and wherein connecting portions of the power supply line, and Rukoto with a common connector connecting portions is set so as to be adjacent to the ground line.

Further, in the torque detector according to the second aspect of the present invention, the distance between the connection portions to the signal line is from the distance between the connection portions to the power line and between the connection portions to the ground line. also features a large Citea Rukoto.

  Furthermore, the torque detector according to a third aspect of the present invention is characterized in that the two magnetic sensors are provided so as to be able to make a fail determination based on a deviation between the outputs.

In the torque detection device according to the first aspect of the present invention, since the two magnetic sensors connected to the outside by two sensor harnesses, each of which includes a power line, a ground line, and a signal line, are provided, each power line or ground line Are short-circuited at the same time, and the outputs of the two magnetic sensors are not lost, and the torque can be detected based on the output of one of the magnetic sensors. In addition, since the connection parts of the power supply line, the ground line and the signal line of the two sensor harnesses are combined, the power supply lines are adjacent to each other, and the grounding lines are adjacent to each other. Even when a short circuit occurs, the output of the magnetic sensor does not fail simultaneously, and torque detection based on the output of one of the magnetic sensors becomes possible.

In the torque detector according to the second aspect of the invention, the distance between the signal line connecting portions in the common connector is increased, so that a short circuit occurring between the signal lines can be minimized, and an accurate torque can be obtained. Detection is possible.

  Furthermore, since the torque detection device according to the third aspect of the present invention includes two magnetic sensors that do not fail at the same time, it is possible to reliably carry out these fail determinations, and to detect the steering torque in the electric power steering device. When used, the present invention has an excellent effect, such as enabling life extension control when a failure occurs by steering assist based on the output of one of the magnetic sensors.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is an exploded perspective view of a torque detector according to the present invention, and FIG. 2 is a longitudinal sectional view showing an assembled state.

  The torque detection device according to the present invention detects torque applied to two shafts (first shaft 1 and second shaft 2) coaxially connected via a torsion bar 3, and rotates integrally with the first shaft 1. And a set of two magnetic yokes 5 and 5 that rotate integrally with the second shaft 2.

  The torsion bar 3 is a small-diameter round bar that acts as a torsion spring. The first shaft 1 and the second shaft 2 are connected to the connection holes 10 and 20 formed in the respective shaft center portions in the torsion bar 3. The large-diameter connecting portions 30 and 30 provided at both ends are fitted in and positioned in the circumferential direction as will be described later, and then are connected by being integrated with each other by driving the connecting pins 11 and 21. When rotational torque is applied to the first shaft 1 and the second shaft 2 connected in this manner, the torsion bar 3 is twisted and deformed by the action of the rotational torque, and the first shaft 1 and the second shaft 2 In the meantime, a relative angular displacement corresponding to the magnitude of the rotational torque occurs in the direction of the rotational torque.

  As shown in FIG. 1, the cylindrical magnet 4 that rotates integrally with the first shaft 1 has a plurality of N poles 40, 40... And S poles 41, 41. As shown in FIG. 2, it is externally fitted and fixed to the first shaft 1 via the holding body 42.

  As shown in FIG. 1, the magnetic yokes 5, 5 rotating integrally with the second shaft 2 are provided with a plurality of magnetic pole claws 51, 51... Extending in the circumferential direction on the inner surface of an annular yoke body 50. It is a ring made of a soft magnetic material that is configured with equal distribution. The magnetic pole claws 51, 51... Have a triangular shape reduced toward the extended end, and the two magnetic yokes 5, 5 face the projecting side of the respective magnetic pole claws 51, 51. In addition, they are coaxially positioned in a state where they are alternately arranged in the circumferential direction, and these are integrally held by a resin holding cylinder 52 formed into a cylindrical shape.

  The magnetic yokes 5 and 5 configured as described above are fixed by fitting an extension portion on one side of the holding cylinder 52 to the shaft end portion of the second shaft 2, and as shown in FIG. The magnetic pole claws 51, 51... Of the magnetic yokes 5, 5 exposed on the inner side of the cylinder 52 are assembled so as to face the outer peripheral surface of the cylindrical magnet 4 fitted and fixed to the first shaft 1 with a slight air gap. It has been.

  3 is an explanatory diagram showing the positional relationship in the circumferential direction between the magnetic pole claws 51, 51... Of the magnetic yokes 5, 5 and the N poles 40, 40. FIG. 3 (b) shows the positional relationship at the time of assembly. As shown in this figure, the magnetic yokes 5, 5 and the cylindrical magnet 4 have magnetic pole claws 51, 51. Phase alignment is performed in the circumferential direction so as to coincide with the boundary between the N pole 40 and the S pole 41 arranged on the circumference of the cylindrical magnet 4. This phase alignment is realized by adjusting the circumferential positions of the cylindrical magnet 4 and the magnetic yokes 5 and 5 together with the shafts 1 and 2 when the first shaft 1 and the second shaft 2 are connected by the torsion bar 3. .

  In such an assembled state, the magnetic pole claws 51, 51... Of the two magnetic yokes 5, 5 are magnetic fields formed between the N pole 40 and the S pole 41 adjacent to each other on the circumference of the cylindrical magnet 4. The magnetic fluxes generated in the yoke main bodies 50, 50 that are located under the same conditions and communicate with the bases of these magnetic pole claws 51, 51,.

  When relative angular displacement occurs with torsion of the torsion bar 3 between the first shaft 1 to which the cylindrical magnet 4 is fixed and the second shaft 2 to which the magnetic yokes 5 and 5 are fixed, each magnetic yoke 5 , 5 magnetic pole claws 51, 51... And the phases of the N pole 40 and the S pole 41 of the cylindrical magnet 4 change in opposite directions as shown in FIG. 3 (a) or 3 (c). When this phase change occurs, magnetic field lines having opposite polarities increase on the magnetic pole claws 51, 51... Of one magnetic yoke 5 and the magnetic pole claws 51, 51. Positive and negative magnetic fluxes are generated in the yoke bodies 50 and 50. The sign of the magnetic flux generated at this time is determined according to the direction of the relative angular displacement generated between the cylindrical magnet 4 and the magnetic yokes 5, 5, that is, between the first shaft 1 and the second shaft 2. The density of the magnetic flux corresponds to the magnitude of the relative angular displacement.

  Two magnetism collecting rings 6 and 6 are arranged outside the magnetic yokes 5 and 5. These magnetic flux collecting rings 6 and 6 are circular rings made of a soft magnetic material having an inner diameter slightly larger than the outer diameter of the yoke main bodies 50 and 50, and are separated by an appropriate length in the circumferential direction as shown in FIG. Magnetic flux collecting projections (magnet collecting portions) 60, 60 extending in the axial length direction and bending the tip portion radially outward are provided at places. The two magnetism collecting rings 6 and 6 are arranged coaxially with the extension sides of the magnetism collecting projections 60 and 60 facing each other, and the bent portions of the respective tips are opposed to each other with a predetermined air gap therebetween. As shown in FIG. 2, the resin is positioned and held integrally with a resin holding cylinder 61, and is fitted into a housing 8 partially shown in FIG. 2 via the holding cylinder 61. The inner peripheral surfaces of the magnetic yokes 5 and 5 are assembled so as to be close to and opposed to the outer peripheral surfaces of the yoke bodies 50 and 50 of the different magnetic yokes 5 and 5, respectively.

  In the magnetic flux collecting rings 6 and 6 assembled in this way, magnetic flux generated inside the yoke main bodies 50 and 50 located inside thereof is induced. This magnetic flux is focused on the tip of each of the separate magnetic flux collecting projections 60, 60 and leaks into the air gap between them.

  Between the two magnetic flux collecting protrusions 60 and 60 of the magnetic flux collecting rings 6 and 6, magnetic sensors 7 and 7 using magnetic detecting elements such as Hall elements are respectively arranged. The magnetic sensors 7, 7 are connected to a common circuit board 70 having peripheral circuits such as a power supply circuit and a signal processing circuit by separate leads 71, 71. As shown in FIG. 2, the circuit board 70 is supported on the outside by a resin support leg 62 connected to a part of the outer periphery of the holding cylinder 61, and the magnetic sensors 7 and 7 are separately provided. Are positioned within an air gap secured between the separate magnetic flux collecting projections 60, 60. The magnetic sensors 7 and 7 arranged in this way emit an output corresponding to the magnetic flux density leaking into each air gap.

  The outputs of the magnetic sensors 7 and 7 are changed by the generated magnetic fluxes in the yoke bodies 50 and 50 facing the magnetic flux collecting rings 6 and 6, and these generated magnetic fluxes are displaced relative to the cylindrical magnet 4 as described above. That is, since it corresponds to the relative angular displacement between the first axis 1 and the second axis 2, the outputs of the magnetic sensors 7 and 7 are applied to the first axis 1 and the second axis 2, and the relative angular displacement. The rotational torque applied to the first shaft 1 and the second shaft 2 can be detected based on the output change of the magnetic sensors 7 and 7.

  As shown in FIG. 2, two sensor harnesses 8, 8 for connecting the magnetic sensors 7, 7 to the outside are connected to the circuit board 70 via a common connector 80. The characteristic of the torque detection device according to the present invention is the configuration of the sensor harnesses 8 and 8 and the connector 80.

  FIG. 4 is an explanatory diagram showing the configuration of the sensor harnesses 8 and 8. As described above, the magnetic sensors 7, 7 using Hall elements require a power line 7V for power connection, a ground line 7G for ground connection, and a signal line 7S for signal extraction. The sensor harnesses 8 and 8 are configured such that the power supply line 7V, the ground line 7G, and the signal line 7S provided in the magnetic sensors 7 and 7 are combined into one, and are individually covered with insulation.

  Accordingly, a short circuit inside each of the sensor harnesses 8 and 8 occurs only between the power line 7V, the ground line 7G and the signal line 7S of one magnetic sensor 7, and the power line 7V of the other magnetic sensor 7 and the ground. There is no effect on the line 7G and the signal line 7S, and a short circuit occurring between the sensor harnesses 8 and 8 and the outside also causes a power line 7V, a ground line 7G or a signal line 7S of the corresponding magnetic sensor 7. The power supply line 7V, the ground line 7G, and the signal line 7S of the other magnetic sensor 7 are not affected at all, and the power supply to the magnetic sensor 7 is normally performed, and the torque corresponding to the power supply is increased. Detection operation is guaranteed.

  FIG. 5 is an explanatory diagram showing a configuration example of the connector 80. The illustrated connector 80 is a widely used 8-pin type connector, and includes four connecting portions arranged in two rows. TV1 and TV2 in the figure indicate the connection parts of the power lines 7V and 7V of the two magnetic sensors 7, 7, GND1, GND2 indicate the connection parts of the ground lines 7G and 7G, and TS1 and TS2 The connection part of the signal lines 7G and 7G is shown.

  As shown in the figure, the four connection portions in one row of the connector 80 are set in the order of TS1, GND1, GND2, and TS2, and the four connection portions in the other row are set in the middle two as TV1 and TV2. The TS1, GND1, and TV1 connected to one sensor harness 8 are arranged on one half, and the TS2, GND2, and TV2 connected to the other sensor harness 8 are arranged on the other side. In the connector 80 in which the connection portion is set in this way, there is a possibility that a short circuit may occur between adjacent connection portions, but a short circuit that occurs between GND1 and GND2 or between TV1 and TV2 The magnetic sensors 7 and 7 are short-circuited between the ground lines 7G and 7G or between the power supply lines 7V and 7V, and the power supply to the magnetic sensors 7 and 7 is normally performed. 7,7 detection operation is also guaranteed.

  In addition, since the short circuit that occurs between GND1 and TS1 or TV1 or between GND2 and TS2 or TV2 is completed on the corresponding magnetic sensor 7 side, the power supply to the other magnetic sensor 7 is normal. Thus, the detection operation of the magnetic sensor 7 is guaranteed.

  The outputs of the two magnetic sensors 7 and 7 are given to a torque calculation unit (not shown) via different sensor harnesses 8 and 8, and the torque calculation unit calculates torque. FIG. 6 is a flowchart illustrating an example of a torque calculation procedure.

The torque calculation unit takes the outputs T ₁ and T ₂ of the magnetic sensors 7 and 7 at a predetermined sampling period (step S1), calculates the deviation ΔT (step S2), and the deviation ΔT is a predetermined upper limit. It is determined whether or not the value T _max is exceeded (step S3).

When it is determined that the deviation ΔT is equal to or less than the upper limit value T ₀ (step S3: NO), the torque calculation unit recognizes that both the outputs T ₁ and T ₂ of the two magnetic sensors 7 and 7 are normal. Then, torque is calculated using these outputs T ₁ and T ₂ (step S4), and the process returns to step S1 to take in new outputs T ₁ and T ₂ and repeat the above-described operation. The calculation of the torque in step S4 can be performed by applying one or both of the outputs T ₁ and T ₂ of the magnetic sensors 7 and 7 to a predetermined arithmetic expression or map.

In step S3, if the deviation ΔT is determined to have exceeded the upper limit T ₀ (step S3: YES), the torque calculation unit determines that there is an abnormality in one of the two magnetic sensors 7, 7, then Then, it is determined whether or not the abnormality is confirmed (step S5). This determination can be performed, for example, by counting the number of times of abnormality determination in step S3 and determining whether or not this count value exceeds a predetermined upper limit value.

When it is determined in step S5 that the abnormality is not confirmed (step S5: NO), the torque calculation unit uses the previous sample value or the outputs T ₁ and T ₂ of the magnetic sensors 7 and 7 before the abnormality determination. The torque is calculated (step S6), and when it is determined that the abnormality is confirmed (step S5: YES), the torque is calculated using the normal output T ₁ or T ₂ (step S7). In this case, the process returns to step S1 to take in new outputs T ₁ and T ₂ and repeat the above-described operation.

It should be noted that the result of the abnormality confirmation is maintained once it is confirmed, and torque calculation using the normal output T ₁ or T ₂ is continued after the confirmation. After the abnormality is determined, the obtained torque calculation value is used as a torque value under the abnormal condition. For example, when the vehicle is used for detection of steering torque in the electric power steering device, the vehicle is safely used. Used for emergency steering control (life extension control) for the purpose of moving to a position. In this case, it is desirable to notify the occurrence of an abnormality of the driver by notifying means such as generation of an alarm and appropriate display.

On the other hand, if the abnormality is not confirmed in step S5, the process proceeds to step S4 when normality is determined in step S3 (step S3: NO), so _one of the outputs T ₁ and T ₂ of the magnetic sensors 7 and 7 or It is possible to return to a normal torque calculation operation using both. Thereby, it is possible to cope with temporary output fluctuations of the magnetic sensors 7 and 7 caused by various disturbances.

In the torque detection device according to the present invention, since the power supply line 7V, the ground line 7G, and the signal line 7S included in each of the magnetic sensors 7 and 7 are separately configured to form the sensor harnesses 8 and 8, both magnetic sensors are provided. power supply to 7,7 is due to the short circuit is blocked at the same time, if the output T _1, T ₂ of the magnetic sensor 7, 7, there is no possibility of failure at the same time, which is applied to an electric power steering apparatus, the aforementioned It is possible to reliably carry out life extension control.

  In addition, a connector 80 for connecting the sensor harnesses 8 and 8 to the circuit board 70 collects the connecting portions to the respective sensor harnesses 8 and 8, and the connecting portions TV1 and TV2 to the respective power supply lines are adjacent to each other. Since the connection portions GND1 and GND2 with the ground line are arranged adjacent to each other, there is no possibility that the power supply to both the magnetic sensors 7 and 7 is simultaneously cut off due to a short circuit in the connector 80.

  It is desirable that the arrangement of the wiring patterns on the circuit board 70 to which the connector 80 is connected be configured so as to obtain a similar adjacency relationship. As a result, the simultaneous failure of the magnetic sensors 7 and 7 due to a short circuit on the circuit board 70 can also be prevented.

It is a disassembled perspective view of the torque detection apparatus which concerns on this invention. It is a longitudinal cross-sectional view which shows the assembly state of the torque detection apparatus which concerns on this invention. It is explanatory drawing which shows the positional relationship of the circumferential direction of the magnetic pole nail | claw of a magnetic yoke, and the magnetic pole of a cylindrical magnet. It is explanatory drawing which shows the structure of a sensor harness. It is explanatory drawing which shows the structural example of a connector. It is a flowchart which shows an example of a torque calculation procedure.

Explanation of symbols

  1 1st axis, 2nd axis, 4 cylindrical magnet, 5 magnetic yoke, 7 magnetic sensor, 8 sensor harness, 7G ground line, 7S signal line, 7V power line, 80 connector

Claims (3)

A cylindrical magnet that rotates integrally with one of the first and second shafts connected on the same axis, a set of two magnetic yokes that rotate integrally with the other, and a magnetic sensor that detects a change in the magnetic flux of these magnetic yokes A torque detector that calculates torque applied to the first and second shafts based on the output of the magnetic sensor;
The includes two magnetic sensors, the two magnetic sensors, Ri each power line, and connecting the ground line and signal line to the outside by two sensor harness summarized individually tare,
The two sensor harnesses are configured so that the connection portions to the power supply line, the ground line, and the signal line are combined, and the connection portions to the power supply line and the connection portions to the ground line are adjacent to each other. torque detecting apparatus according to claim Rukoto provided with the connector. The distance between the connecting portions between the signal lines, the joined portions between the power supply line, and the torque detecting device of Ru increases Citea claim 1 than the distance between the connecting portions between said ground line .   The torque detection device according to claim 1 or 2, wherein the two magnetic sensors are provided so as to be able to perform a fail determination based on a deviation between respective outputs.

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