JP5211583B2 - Torque detection device - Google Patents

Description

  The present invention relates to a torque detection device that detects a steering torque applied to a steering member of a vehicle for steering.

  2. Description of the Related Art In recent years, an electric power steering apparatus equipped with an electric motor as an actuator for assisting steering is widely equipped for the purpose of reducing the labor burden of a driver required for steering. In this electric power steering device, a steering torque applied to a steering member such as a steering wheel is detected by a torque detection device arranged in the middle of a steering shaft that connects the steering member and the steering mechanism, and the detected steering torque is detected. The steering assist motor is driven and controlled based on the direction and size, and the generated force of the motor is applied to the steering mechanism.

In such an electric power steering apparatus, generally an electromagnetic coupling type torque detection apparatus is used (see Patent Documents 1 and 2). In this case, the steering shaft to be detected is divided into a first shaft on the steering member side and a second shaft on the steering mechanism side, and these are coaxially arranged to allow relative angular displacement by a small diameter torsion bar. Connected.
The electromagnetic coupling type torque detection device includes first and second magnetic rings that are fitted to each of the first and second shafts, and a plurality of teeth facing each other are juxtaposed on the end surfaces of the first and second magnetic rings. A magnetic circuit is constituted by excitation coils spaced apart on the outer circumference of each magnetic ring, and a steering torque applied to the steering shaft is detected based on a change in impedance of the excitation coil.

  Here, the steering shaft is rotatably supported inside the column housing, and the excitation coil is fixed to the column housing. For example, an ECU and a power source for supplying power to the excitation coil are connected to the excitation coil by signal lines and power lines. Are connected by a cable having The ECU calculates a steering torque based on a change in impedance of the exciting coil.

As a torque detection device other than the electromagnetic coupling type torque detection device, a cord reel type torque detection device is known. In the cord reel type torque detection device, a sensor for detecting a physical quantity (steering shaft distortion, torsion, etc.) relating to steering torque applied to the steering shaft is attached to the steering shaft, and the ECU and the sensor are supplied with power to this sensor. A power source is connected by a cable having a signal line and a power line. The ECU calculates the steering torque based on the physical quantity detected by the sensor. The cord reel type torque detection device is highly reliable because it directly detects a physical quantity related to the steering torque applied to the steering shaft by a sensor attached to the steering shaft.
JP-A-11-248561 JP 2003-11833 A

However, since the cord reel type torque detection device has a sensor mounted on the rotating steering shaft, the cable connected to the sensor is disposed so as to surround the steering shaft so as not to hinder the rotation of the steering shaft, Furthermore, it is necessary to allow a cable length to increase or decrease the number of turns on the steering shaft in accordance with the rotation of the steering shaft, which makes it difficult to reduce the size and cost.
In addition, some use slip rings instead of cables, but reliability tends to decrease due to slip ring wear, poor contact, and the like.

  On the other hand, the electromagnetic coupling type torque detection device does not need to connect a cable to an article mounted on the rotating steering shaft, but is on the rotating side in order to detect a physical quantity related to the steering torque applied to the steering shaft. The magnetic ring is attached around the steering shaft, and the excitation coil must be attached to the column housing on the fixed side separately from the magnetic ring while surrounding the magnetic ring. Have difficulty.

  The present invention has been made in view of such circumstances, and an object of the present invention is to detect a steering torque applied to a steering shaft with high accuracy, and to reduce the cost, reduce the size, and increase the reliability. Is to provide.

A torque detector according to a first aspect of the present invention includes a sensor that is attached to a steering shaft that transmits an operation of a steering member to a steering mechanism and detects a physical quantity related to steering torque applied to the steering shaft, and is arranged in the middle of the steering shaft. In the torque detection device for detecting a steering torque applied to the steering member for steering, the torque detection device is attached to the steering shaft, connected to the sensor, supplies power to the sensor, and the detection result of the sensor is obtained. An IC tag that wirelessly transmits a signal to be indicated, a power supply unit that supplies power to the IC tag in a non-contact manner, a reception unit that receives a signal transmitted by the IC tag, and the physical quantity indicated by the signal received by the reception unit and a calculating means for calculating a steering torque based on the values, a plurality of the IC tag, the reception unit, at least two of said IC tag When the received signal is received simultaneously, the calculating means falls within the predetermined range when the physical quantity value indicated by the at least one signal received by the receiving unit is within the predetermined range. characterized Citea Rukoto to calculate the steering torque based on the value of the physical quantity is.

Torque detecting apparatus according to the second invention, two said IC tag even without least is characterized by being disposed in a position facing the radial direction of the steering shaft.

  The torque detector according to a third aspect is characterized in that the IC tag transmits signals at different frequencies.

  A torque detector according to a fourth aspect of the present invention further includes an antenna that is connected to the IC tag and is disposed on the entire circumference of the steering shaft.

  A torque detection device according to a fifth aspect of the present invention is further characterized in that a plurality of antennas are connected to the IC tag, and are further provided with antennas respectively arranged at positions opposed to the radial direction of the steering shaft.

  In the case of the torque detection device according to the first aspect of the invention, since a sensor for detecting a physical quantity related to the steering torque applied to the steering shaft is attached to the steering shaft, it is not necessary to use a magnetic ring and an excitation coil. In addition, an IC tag that performs power supply and communication with a wire to the sensor is attached to the steering shaft, power is supplied to the IC tag in a non-contact manner, and communication is performed wirelessly. There is no need to connect with a cable, slip ring, etc. As a result of the above, the present invention has superior effects in three points of reliability, downsizing, and cost performance as compared with the conventional torque detector.

  In the case of the torque detection device according to the second aspect of the invention, since at least two IC tags are arranged at positions opposed to the steering shaft in the radial direction, for example, a complicated configuration is adopted in which an external antenna is connected to the IC tag. Rather, using the internal antenna of the IC tag, non-contact power feeding to the IC tag by the power feeding unit and wireless communication between the receiving unit and the IC tag are possible regardless of the rotational position of the IC tag.

  In the case of the torque detection device according to the third aspect of the invention, since a plurality of IC tags that transmit signals at different frequencies are provided, radio waves are generated when signals from the plurality of IC tags are received simultaneously depending on the rotational position of each IC tag. Therefore, the receiving unit can receive an accurate signal.

  In the case of the torque detection device according to the fourth aspect of the invention, since the antenna connected to the IC tag is arranged all around the steering shaft, non-contact power feeding to the IC tag by the power feeding unit and wireless communication between the receiving unit and the IC tag However, this is certainly possible regardless of the rotational position of the IC tag.

  In the case of the torque detection device according to the fifth aspect of the invention, since the antenna connected to the IC tag is disposed at a position facing the radial direction of the steering shaft, non-contact power feeding to the IC tag by the power feeding unit and the receiving unit and the IC tag Wireless communication is possible regardless of the rotational position of the IC tag, and a compact configuration can be achieved without arranging an antenna all around the steering shaft.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

Embodiment 1.
FIG. 1 is a schematic diagram illustrating an overall configuration of an electric power steering apparatus including a torque detection device according to Embodiment 1 of the present invention.
In the figure, reference numeral 7 denotes an electric power steering device. The electric power steering device 7 includes a rack shaft 1 supported in a rack housing 10 extending in the left-right direction of the vehicle so as to be movable in the axial direction, a rack A rack and pinion type steering mechanism 9 having a pinion shaft 2 rotatably supported inside a pinion housing 20 that intersects the middle of the housing 10 is provided.

  Both ends of the rack shaft 1 protrude outward from both sides of the rack housing 10 and are connected to left and right front wheels 12, 12 as steering wheels via separate tie rods 11, 11. One end of the pinion shaft 2 protrudes outward from the upper portion of the pinion housing 20 and is connected to the lower end of the steering shaft 3 facing the upper position. A pinion (not shown) is formed in the lower half of the pinion shaft 2 extending inside the pinion housing 20, and the pinion is formed on the rack shaft 1 over an appropriate length at the intersection with the rack housing 10. It meshes with the rack.

  The steering shaft 3 is rotatably supported inside a cylindrical column housing 31, and is supported via the column housing 31 while maintaining an inclined posture with the front facing down inside a passenger compartment (not shown). Both ends of the steering shaft 3 protrude to the outside from the upper and lower sides of the column housing 31, and the pinion shaft 2 is connected to the lower protruding end as described above, and the upper protruding end serves as a steering member. A steering wheel 30 is fixed.

  With the above configuration, when the steering wheel 30 is rotated for steering, this rotation is transmitted to the pinion shaft 2 via the steering shaft 3, and the pinion shaft 2 rotates around the axis. When the pinion shaft 2 rotates, the rotation of the pinion provided in the lower half is converted in motion at the meshing portion with the rack, and the rack shaft 1 moves in the axial direction in the rack housing 10. The movement of the rack shaft 1 thus generated is transmitted to the left and right front wheels 12 and 12 via the tie rods 11 and 11 at both ends, and the front wheels 12 and 12 are pushed and pulled to be steered.

  An electric power steering device 7 shown in FIG. 1 includes an electric motor 4 that assists steering performed as described above, and a torque detection device 5 that detects a steering torque applied to the steering shaft 3 by a rotating operation of the steering wheel 30. And.

  The steering assisting motor 4 is attached to the outside in the vicinity of the lower end of the column housing 31 so that the shaft center is substantially orthogonal, and includes, for example, a worm and a worm wheel for rotating the output shaft extending inside the column housing 31. The transmission is configured so that it is decelerated by a worm gear reducer and transmitted to the steering shaft 3, and a rotational force is applied to the steering shaft 3. With this configuration, the rotational force of the motor 4 is decelerated and transmitted to the steering shaft 3 and is transmitted to the rack shaft 1 via the pinion shaft 2 connected to the lower end of the steering shaft 3. The steering performed as described above can be assisted.

As shown by a broken line in FIG. 1, the torque detection device 5 is provided inside the column housing 31 at a position higher than the mounting portion of the steering assist motor 4.
2 is a side view showing the arrangement of the IC tag, sensor, and antenna with respect to the steering shaft provided in the torque detection device according to Embodiment 1 of the present invention, and FIG. 3 is a cross-sectional view schematically showing this arrangement. FIG. 4 is a block diagram showing the configuration of the IC tag.

  The torque detection device 5 includes a sensor 50 using a resistor that can be expanded and contracted in order to detect a minute twist generated in the steering shaft 3 itself by the operation of the steering wheel 30 for steering. In the present embodiment, in order to supply power to the sensor 50 and to give the output of the sensor 50 to the assist control unit 6 described later, RFID (Radio Frequency IDentification: wireless communication) is used without using a cable, a slip ring, or the like. Non-contact automatic recognition technology using non-contact power) and wireless communication using technology.

The sensor 50 is a strain gauge, and is directly attached to the middle peripheral surface of the steering shaft 3 supported by the bearings 32 and 32 inside the column housing 31 using, for example, an adhesive.
A non-metal (for example, synthetic resin) ring 59 is externally fitted near the sensor 50 of the steering shaft 3, and the IC tag 51 and the external antenna 52 are indirectly attached to the steering shaft 3 via the ring 59. It has been.
The external antenna 52 is formed by using an antenna wire, is stretched around the entire circumference of the steering shaft 3 on the circumferential surface of the ring 59, and is further connected to the IC tag 51 by wire. Here, the external antenna 52 is disposed at a predetermined position in the axial direction of the steering shaft 3 so as to face an antenna 70a of a power receiving unit 70 described later.

The IC tag 51 includes a control unit 510, a power reception unit 511, a transmission unit 512, and a sensor circuit 513. The power reception unit 511 and the transmission unit 512 are connected to the external antenna 52 by wires.
The power reception unit 511 is connected to the control unit 510, the transmission unit 512, and the sensor circuit 513 by wires. The power receiving unit 511 includes a resonance circuit that generates electromotive force by radio waves received by the external antenna 52, a rectifier circuit that rectifies the generated electromotive force, and the like. Power is supplied to each of the unit 512 and the sensor circuit 513.

  By the way, the sensor 50 expands and contracts as the steering shaft 3 is twisted when the steering torque is applied to the steering shaft 3, and the resistance value increases or decreases according to the amount of expansion or contraction. For example, when the steering torque is applied in the direction of the white arrow shown in FIG. 2 (or the direction opposite to the direction of the white arrow), the sensor 50 expands (or contracts), and the steering torque is applied to the steering shaft 3. In the absence, the sensor 50 does not expand or contract.

On the other hand, the sensor circuit 513 includes a plurality of fixed resistors connected by wire so that the bridge circuit B including the sensor 50 is formed, and the sensor circuit 513, the power receiving unit 511, and the control unit 510 are connected by wire. ing.
A constant DC voltage is applied from the power reception unit 511 to the sensor circuit 513. More specifically, the input voltage V _in as an output voltage value of the bridge circuit B becomes "0" when no steering torque is applied to the steering shaft 3 is applied to the bridge circuit B.
When the magnitude and direction of the steering torque applied to the steering shaft 3 is changed by the operation of the steering wheel 30, the magnitude and positive / negative of the output voltage value of the bridge circuit B change correspondingly to this change.

The output voltage V _out of the bridge circuit B is given from the sensor circuit 513 to the control unit 510. The control unit 510 is connected to the transmission unit 512 by a wire, and provides the transmission unit 512 with a detection signal S indicating the value of the output voltage V _out provided from the sensor circuit 513. The transmission unit 512 is configured to transmit a radio wave of a predetermined frequency, and the detection signal S given from the control unit 510 is superimposed on the radio wave transmitted by the transmission unit 512 and transmitted wirelessly via the external antenna 52. Is done.
As described above, the IC tag 51 supplies power to the sensor 50 and wirelessly transmits a signal indicating the detection result of the sensor 50.

The IC tag 51 may be directly attached to the steering shaft 3 without using the ring 59. Further, instead of the ring 59, for example, a configuration including an insulating layer formed on the surface of the steering shaft 3 may be employed.
Further, the IC tag 51 may include an internal antenna, and contactless power feeding and wireless communication may be performed using not only the external antenna 52 but also the internal antenna.

  The power supply receiving unit 70 uses a tag reader / writer and has a function of a power supply unit that supplies power to the IC tag 51 in a contactless manner and a function of a reception unit that wirelessly receives the detection signal S transmitted by the IC tag 51. Has been. For this purpose, the power receiving unit 70 includes an antenna 70 a, and is attached to the column housing 31 so that at least the antenna 70 a is disposed opposite to the external antenna 52 inside the column housing 31. The power receiving unit 70 is operated by being supplied with power from a power supply 80 connected by wire, transmits a radio wave of a predetermined frequency via the antenna 70a, and receives a radio wave transmitted by the IC tag 51, The detection signal S superimposed on the received radio wave is transmitted to the assist control unit 6 connected by wire.

That is, the power supplied from the power supply 80 to the power supply receiving unit 70 is supplied from the power supply reception unit 70 to the IC tag 51 via the external antenna 52 in a non-contact manner, and is supplied from the IC tag 51 to the sensor 50. The detection result of the sensor 50 is output from the sensor 50 to the IC tag 51, and the detection signal S indicating the detection result of the sensor 50 is wirelessly transmitted from the IC tag 51 to the power receiving unit 70 via the external antenna 52, and the power receiving unit 70 to the assist control unit 6 which is a calculation means.
The assist control unit 6 includes a CPU, a ROM, and a RAM, and is configured as an ECU that executes the following control operation by the operation of the CPU in accordance with a control program stored in the ROM. The steering torque is calculated based on the output voltage value indicated by the detection signal S given from the receiving unit 70.

  As shown in FIG. 1, the output of the assist control unit 6 is given to the drive circuit of the steering assist motor 4 described above, and the motor 4 is driven in accordance with a control command given from the assist control unit 6. It ’s like that. The assist control unit 6 is provided with a detected value of the drive current of the motor 4 from a motor current sensor 40 attached to the steering assisting motor 4, and further from a running state sensor 60 provided in each part of the vehicle. Further, detection results of running conditions that affect steering such as vehicle speed and yaw rate are given.

  The assist control unit 6 takes in the detection signal S output from the power supply receiving unit 70 at an appropriate sampling period, calculates the steering torque applied to the steering shaft 3 for steering, and stores the calculated steering torque detection value in the ROM. The steering assist force to be generated by the steering assist motor 4 is calculated by applying it to the assist force map stored in the vehicle, and an operation command is issued to the steering assist motor 4 to generate the steering assist force. The motor 4 is assisted and driven. That is, the assist control unit 6 serves both as a calculation unit of the torque detection device 5 and a control unit of the electric power steering device 7.

  This assist drive is performed by feedback control using the detection value of the drive current given from the motor current sensor 40, and the steering assist force generated by the motor 4 by this drive is applied to the rack shaft 1, and the steering is performed as described above. Can assist. The assist force map used for calculating the target assist force is set for each travel state that affects steering such as the vehicle speed and the yaw rate, and the detection result of the travel state by the travel state sensor 60 is used for selecting the assist force map. It is done. Thereby, appropriate steering assistance is executed according to the traveling state.

Since the torque detection device 5 as described above does not need to use a magnetic ring and an excitation coil as provided in the electromagnetic coupling type torque detection device, the configuration is simple and the size can be easily reduced. Further, since it is not necessary to use a cable that is provided in the cord reel type torque detection device, it is not necessary to connect the cable to the sensor 50 and to wind the cable around the steering shaft 3, and it is easy to reduce the size and cost. is there. Further, since it is not necessary to use a slip ring, reliability is not lowered due to wear of the slip ring, contact failure, or the like. That is, the torque detector 5 is highly reliable.
Further, since the sensor 50 is directly attached to the steering shaft 3, a physical quantity related to the steering torque applied to the steering shaft 3 can be directly detected, and the steering torque is calculated with high accuracy based on the detection result. can do.

  Further, since radio waves are exchanged between the external antenna 52 and the antenna 70 a arranged on the entire circumference of the steering shaft 3, the IC tag 51 that rotates as the steering shaft 3 rotates and the column housing 31 are fixed. Regardless of the positional relationship with the antenna 70a, the contactless power feeding from the power receiving unit 70 to the IC tag 51 and the wireless communication from the IC tag 51 to the power receiving unit 70 are reliably performed.

The physical quantity detected by the sensor 50 is not limited to the twist as long as it is a physical quantity related to the steering torque applied to the steering shaft 3. The sensor 50 may be configured to detect the presence / absence and change of the twist generated in the steering shaft 3 as a change in its own capacitance, inductance, and the like.
Further, the steering shaft 3 may be configured by using the first and second shafts and the torsion bar, and the sensor 50 may be attached to the torsion bar.
Furthermore, the configuration is not limited to the configuration in which the assist control unit 6 calculates the steering torque. For example, a configuration in which a calculation circuit that calculates the steering torque is arranged in the control unit 510 or the power supply reception unit 70 and the calculation result is given to the assist control unit 6. It is good.

Embodiment 2. FIG.
FIG. 5 is a side view showing the arrangement of the IC tag, sensor, and antenna with respect to the steering shaft provided in the torque detection device according to Embodiment 2 of the present invention, and FIG. 6 is a cross-sectional view schematically showing this arrangement. FIG. 7 is a block diagram showing the configuration of the IC tag.
In the figure, reference numeral 5 denotes a torque detection device. The torque detection device 5 of the present embodiment is substantially the same as the torque detection device 5 of the first embodiment, and is substantially the same as the electric power steering device 7 of the first embodiment. The electric power steering device 7 is provided.
Hereinafter, differences from the first embodiment will be described, and other parts corresponding to those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  The torque detection device 5 according to the present embodiment includes an IC tag 53 and external antennas 54 and 54 instead of the IC tag 51 and the external antenna 52 of the first embodiment. The control unit 530, the power reception unit 531, the transmission unit 532, and the sensor circuit 533 built in the IC tag 53 are the control unit 510, the power reception unit 511, the transmission unit 512, and the control circuit 513 built in the IC tag 51 of the first embodiment. The sensor circuit 533 is substantially the same as the sensor circuit 513, and the sensor circuit 533 includes a plurality of fixed resistors connected in a wired manner so that the bridge circuit B including the sensor 50 is formed.

  Each external antenna 54 is formed by, for example, forming an antenna wire in a coil shape, and is connected to the power reception unit 531 and the transmission unit 532 by wire. The external antennas 54 and 54 are arranged at predetermined positions in the axial direction of the steering shaft 3 so as to be able to face the antenna 70a of the power receiving section 70, and are arranged at positions facing the radial direction of the steering shaft 3, respectively. ing. That is, the external antennas 54 and 54 are spaced apart by 180 ° in the circumferential direction of the steering shaft 3.

  Therefore, the electric power supplied from the power supply 80 to the power receiving unit 70 is supplied from the power receiving unit 70 to the IC tag 53 in a non-contact manner via the external antennas 54 and 54, and is supplied from the IC tag 53 to the sensor 50. The detection result of the sensor 50 is output from the sensor 50 to the IC tag 53, and the detection signal S indicating the detection result of the sensor 50 is transmitted from the IC tag 53 to the power supply receiving unit 70 wirelessly via the external antennas 54 and 54. The signal is given from the receiving unit 70 to the assist control unit 6 which is a calculation means.

  The torque detection device 5 as described above has the same effect as the torque detection device 5 of the first embodiment. In addition, since radio waves are exchanged between the external antennas 54 and 54 and the antenna 70a that are spaced apart by 180 ° in the circumferential direction of the steering shaft 3, an IC tag 53 that rotates as the steering shaft 3 rotates, Regardless of the positional relationship with the antenna 70 a fixed to the column housing 31, non-contact power feeding from the power receiving unit 70 to the IC tag 53 and wireless communication from the IC tag 53 to the power receiving unit 70 are performed. It is. In addition, since it is not necessary to arrange an antenna wire all around the steering shaft 3, the configuration is compact.

Embodiment 3. FIG.
FIG. 8 is a side view showing the arrangement of the IC tag, sensor and antenna with respect to the steering shaft provided in the torque detection device according to the third embodiment of the present invention, and FIG. 9 is a cross-sectional view schematically showing this arrangement. FIG. 10 is a block diagram showing the configuration of the IC tag.
In the figure, reference numeral 5 denotes a torque detection device. The torque detection device 5 of the present embodiment is substantially the same as the torque detection device 5 of the first embodiment, and is substantially the same as the electric power steering device 7 of the first embodiment. The electric power steering device 7 is provided.
Hereinafter, differences from the first embodiment will be described, and other parts corresponding to those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  The torque detection device 5 according to the present embodiment includes IC tags 55 and 56 instead of the IC tag 51 and the external antenna 52 according to the first embodiment. The control unit 550, the power reception unit 551, the transmission unit 552, and the sensor circuit 553 that are included in the IC tag 55 are the control unit 510, the power reception unit 511, the transmission unit 512, and the control circuit that are included in the IC tag 51 of the first embodiment. The sensor circuit 553 is substantially the same as the sensor circuit 513, and the sensor circuit 553 includes a plurality of fixed resistors connected in a wired manner so that the bridge circuit B including the sensor 50 is formed. Further, the IC tag 55 includes an internal antenna 554, and the internal antenna 554 is connected to the power reception unit 551 and the transmission unit 552 by wire. The IC tag 55 is disposed at a predetermined position in the axial direction of the steering shaft 3 so that the internal antenna 554 can face the antenna 70a of the power receiving section 70.

The configuration of the IC tag 56 is substantially the same as that of the IC tag 55, but the frequency of the radio wave transmitted by the transmission unit 552 of the IC tag 55 and the frequency of the radio wave transmitted by a transmission unit (not shown) of the IC tag 56 are different from each other. It is.
The IC tags 55 and 56 are respectively arranged at positions facing the steering shaft 3 in the radial direction. That is, the IC tags 55 and 56 are spaced apart by 180 ° in the circumferential direction of the steering shaft 3.

  Therefore, the power supplied from the power supply 80 to the power receiving unit 70 is supplied from the power receiving unit 70 to the IC tags 55 and 56 in a non-contact manner, and is supplied from the IC tags 55 and 56 to the sensor 50. The detection result of the sensor 50 is output from the sensor 50 to the IC tags 55 and 56, and the detection signal S indicating the detection result of the sensor 50 is wirelessly transmitted from the IC tag 55 and 56 to the power supply receiving unit 70. It is given to the assist control unit 6 which is a calculation means.

  The torque detection device 5 as described above has the same effect as the torque detection device 5 of the first embodiment. Further, since radio waves are exchanged between the antennas 70a and the IC tags 55 and 56 that are spaced apart by 180 ° in the circumferential direction of the steering shaft 3, the IC tags 55 and 56 that rotate as the steering shaft 3 rotates. And the antenna 70 a fixed to the column housing 31, regardless of the positional relationship, at least one of the IC tags 55, 56 and the non-contact power feeding from the power receiving part 70 to at least one of the IC tags 55, 56 Wireless communication from one side to the power receiving unit 70 is performed. In addition, since non-contact power feeding and wireless communication are performed using the internal antenna 554 of the IC tag 55 and the internal antenna (not shown) of the IC tag 56, it is not necessary to have a complicated configuration in which an external antenna is connected to the IC tag. The structure is compact.

Further, since the IC tags 55 and 56 transmit the detection signals S at different frequencies, the radio waves transmitted by the IC tags 55 and 56 are received simultaneously depending on the positional relationship between the IC tags 55 and 56 and the antenna 70a. Radio wave interference does not occur. Therefore, the power receiving unit 70 receives the detection signal S accurately.
Note that, for example, the power receiving unit 551 of the IC tag 55 is provided with a capacitor, a storage battery, and the like to charge and discharge appropriately, so that the non-contact power feeding from the power feeding receiving unit 70 is temporarily performed depending on the positional relationship between the IC tag 55 and the antenna 70a. Even if the power supply is interrupted, the power supply may be stably supplied to each part of the IC tag 55 such as the control unit 550 and the sensor circuit 553.

The third and fourth IC tags may be provided between the IC tags 55 and 56, for example, 90 ° apart in the circumferential direction of the steering shaft 3 °. In this case, the steering torque can be detected even if one of the four is broken and communication is completely interrupted.
Further, when the detection signal S from the IC tag 55 and the detection signal S from the IC tag 56 are received simultaneously, for example, the magnitude of the output voltage value indicated by each of the two detection signals S and S and the predetermined voltage value is large or small. Based on the relationship, it is determined whether or not each of the detection signals S and S is within a normal range, and when one of the detection signals S and S is abnormal, the steering torque is obtained based on the other normal and detected. When both signals S and S are abnormal, the driver may be notified of the abnormality of the torque detection device 5.

  Further, two sensors may be provided instead of one sensor 50, and IC tags 55 and 56 may be connected to these sensors, respectively. In this case, the steering torque calculated based on the detection signal S from the IC tag 55 and the steering torque calculated based on the detection signal S from the IC tag 56 theoretically coincide with each other. There is no problem even if the steering torque is calculated using the detection signal S from any of them.

It is a schematic diagram which shows the whole structure of the electric power steering apparatus provided with the torque detection apparatus which concerns on Embodiment 1 of this invention. It is a side view which shows arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 1 of this invention, a sensor, and an antenna are provided. It is a cross-sectional view which shows typically arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 1 of this invention, a sensor, and an antenna are provided. It is a block diagram which shows the structure of the IC tag with which the torque detection apparatus which concerns on Embodiment 1 of this invention is provided. It is a side view which shows arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 2 of this invention, a sensor, and an antenna are provided. It is a cross-sectional view which shows typically the arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 2 of this invention, a sensor, and an antenna are equipped. It is a block diagram which shows the structure of the IC tag with which the torque detection apparatus which concerns on Embodiment 2 of this invention is provided. It is a side view which shows arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 3 of this invention, a sensor, and an antenna are provided. It is a cross-sectional view which shows typically the arrangement | positioning with respect to the steering shaft of the IC tag with which the torque detection apparatus which concerns on Embodiment 3 of this invention, a sensor, and an antenna are provided. It is a block diagram which shows the structure of the IC tag with which the torque detection apparatus which concerns on Embodiment 3 of this invention is provided.

Explanation of symbols

  3 Steering shaft, 30 Steering wheel (steering member), 5 Torque detection device, 50 Sensor, 51, 53, 55, 56 IC tag, 52, 54 External antenna, 6 Assist control unit (calculation means), 70 Power feed receiving unit ( (Feeding unit, receiving unit), 9 steering mechanism

Claims (5)

A sensor that is attached to a steering shaft that transmits an operation of the steering member to the steering mechanism and detects a physical quantity related to a steering torque applied to the steering shaft,
In the torque detection device that is arranged in the middle of the steering shaft and detects a steering torque applied to the steering member for steering,
An IC tag attached to the steering shaft, connected to the sensor, supplying power to the sensor, and wirelessly transmitting a signal indicating a detection result of the sensor;
A power supply unit that supplies power to the IC tag in a contactless manner;
A receiver for receiving a signal transmitted by the IC tag;
Calculating means for calculating a steering torque based on the value of the physical quantity indicated by the signal received by the receiving unit ;
A plurality of IC tags,
When the receiving unit simultaneously receives signals transmitted by at least two of the IC tags, the calculation unit is configured such that the physical quantity value indicated by the at least one signal received by the receiving unit is within a predetermined range. torque detecting apparatus according to claim Citea Rukoto as when you are settled, and calculates the steering torque based on the value of the physical quantity is within a predetermined range. Two said IC tag even without low, the torque detection apparatus according to claim 1, characterized in that it is arranged at a position opposed to the radial direction of the steering shaft.   The torque detection device according to claim 2, wherein the IC tag transmits signals at different frequencies.   The torque detection device according to claim 1, further comprising an antenna connected to the IC tag and disposed on an entire circumference of the steering shaft.   The torque detection device according to claim 1, further comprising: an antenna that is connected to the IC tag in a plurality and is disposed at positions facing each other in a radial direction of the steering shaft.

Images