JP2015098223A - Sensor device and electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device which can detect abnormality of a communication part.SOLUTION: A sensor device includes a torque sensor 7 which transmits a first torque detection signal St1 from a first communication part 13 as a digital signal, and a CPU 63 which receives the first torque detection signal St1 through a first communication part 60 and calculates output values of respective hall elements 11a, 12a on the basis of the first torque detection signal St1. The CPU 63 transmits a check signal Sc including a digital value for check to the torque sensor 7 through the first communication part 60. The torque sensor 7 generates an abnormality diagnosis signal Se on the basis of the digital value for check which is received through the first communication part 13 and is included in the check signal Sc, and transmits it to the CPU 63 from the first communication part 13. The CPU 63 receives the abnormality diagnosis signal Se through the first communication part 60, and detects abnormality on the basis of comparison between the digital value for check included in the abnormality diagnosis signal Se and an original value of it.

Description

  The present invention relates to a sensor device and an electric power steering device.

  2. Description of the Related Art There is known an electric power steering device that assists a driver's steering operation by applying a motor assist force to a vehicle steering mechanism. The electric power steering apparatus includes a torque sensor that detects a steering torque applied to a steering mechanism by a driver, and a control device that controls driving of the motor. The torque sensor transmits a detection signal corresponding to the detected steering torque to the control device. The control device receives a detection signal transmitted from the torque sensor via the receiving unit, and calculates a steering torque detection value based on the detection signal. The control device sets an assist command value based on the calculated steering torque detection value, and controls driving of the motor so that the output torque of the motor follows the assist command value.

  As such an electric power steering device, there is one that performs communication between a torque sensor and a control device by digital communication, as can be seen in Patent Document 1, for example. The torque sensor described in Patent Literature 1 includes a detection element, an A / D (analog / digital) converter, and a transmission unit. The detection element is a part that actually detects a physical quantity corresponding to the steering torque, and outputs an analog signal corresponding to the detected physical quantity to the A / D converter. The A / D converter converts an analog signal output from the detection element into a digital signal, and outputs the converted digital signal to the transmission unit. The transmission unit takes in the digital signal output from the A / D conversion unit and stores the value in a register. The transmission unit generates a torque detection signal based on the digital value stored in the register, and transmits the torque detection signal to the control device.

JP 2003-104217 A

  By the way, in such an electric power steering device, if an abnormality occurs in the transmission unit of the torque sensor, the steering torque detection value calculated by the control device may become an abnormal value. For example, when an abnormality occurs such that a bit in the register of the transmission unit is fixed to “0”, the digital value stored in the register is an abnormal value. In such a situation, the torque detection signal generated by the transmission unit becomes an abnormal signal, and as a result, the steering torque detection value calculated by the control device becomes an abnormal value. When the control device performs drive control of the motor based on such an abnormal steering torque detection value, an improper assist force is applied from the motor to the steering mechanism, which may give the driver a sense of discomfort.

  Such a problem may occur not only when an abnormality occurs in the transmission unit of the torque sensor, but also when an abnormality occurs in the reception unit on the control device side. In addition to the torque sensor, a detection unit that transmits a digital signal corresponding to the detected physical quantity as a detection signal via the communication unit, and a detection signal transmitted from the detection unit are received via the communication unit, and this detection is performed. This is a problem common to sensor devices having a calculation unit that calculates a physical quantity detection value based on a signal.

  The present invention has been made in view of such circumstances, and an object of the present invention is to use a sensor device capable of detecting an abnormality in at least one of a detection unit side communication unit and a calculation unit side communication unit, and the sensor device. It is to provide an electric power steering apparatus.

  In order to solve the above problems, a detection unit that transmits a detection signal corresponding to the detected physical quantity as a digital signal from the detection unit side communication unit, and the detection signal transmitted from the detection unit via the calculation unit side communication unit And a calculation unit that receives the detection signal and executes a calculation based on the detection signal, wherein the calculation unit receives a check signal including a check digital value based on the reception of the detection signal. When the check unit receives the check signal via the detection unit side communication unit, the detection unit generates an abnormality diagnosis signal based on the check digital value included in the check signal. The abnormality diagnosis signal is transmitted from the detection unit side communication unit to the calculation unit, and the calculation unit transmits the abnormality diagnosis signal transmitted from the detection unit via the calculation unit side communication unit. The abnormality is detected in at least one of the detection unit side communication unit and the calculation unit side communication unit based on a comparison between the check digital value included in the abnormality diagnosis signal and the original value of the check digital value. It was decided to detect.

  According to this configuration, when an abnormality occurs in at least one of the detection unit side communication unit or the calculation unit side communication unit, the detection unit side communication unit transmits an abnormality diagnosis signal, or the calculation unit side communication unit diagnoses an abnormality. When the signal is received, the check digital value included in the abnormality diagnosis signal becomes an abnormal value. Therefore, the calculation unit can detect an abnormality in the detection unit side communication unit or the calculation unit side communication unit when the check digital value included in the abnormality diagnosis signal is different from the original value of the check digital value.

  According to the above configuration, when the detection unit transmits a detection signal to the calculation unit, the calculation unit transmits a check signal to the detection unit. And based on this check signal, a detection part transmits an abnormality diagnosis signal to a calculating part. That is, the detection unit transmits the detection signal and the abnormality diagnosis signal to the calculation unit. As a result, the calculation unit can detect the abnormality based on the abnormality diagnosis signal while calculating the physical quantity detection value based on the detection signal, thereby satisfying the function as the sensor device and ensuring high reliability. Can do.

In the sensor device, it is preferable that the detection unit transmits the abnormality diagnosis signal and the detection signal based on reception of the check signal.
According to this configuration, since the calculation unit can acquire not only the abnormality diagnosis signal but also the detection signal by transmitting the check signal to the detection unit, the calculation unit requests the detection unit to transmit the detection signal. There is no need. Therefore, the communication time between the calculation unit and the detection unit can be shortened.

  In the sensor device, the detection unit includes a plurality of detection elements that detect the same physical quantity and perform outputs that have a correlation with the physical quantity, and that includes each output value of the plurality of detection elements. Preferably, the signal is transmitted as the detection signal, and the calculation unit further detects an abnormality of the detection element based on a correlation between output values of the plurality of detection elements.

  According to this configuration, when an abnormality occurs in any of the plurality of detection elements, the correlation between the output values is lost. Therefore, the calculation unit can detect an abnormality in the plurality of detection elements when there is no correlation between the output values of the plurality of detection signals acquired from the detection signal.

  And a motor for applying an assist force to the steering mechanism of the vehicle and a torque sensor for detecting a steering torque applied to the steering mechanism, and driving the motor based on the steering torque detected by the torque sensor. In the electric power steering device to be controlled, it is preferable that the sensor device as described above is used as the torque sensor.

  According to this configuration, the abnormality of the torque sensor can be detected more reliably, so that the reliability of the torque sensor can be improved. Therefore, a more appropriate assist force can be applied to the steering mechanism.

  According to these sensor devices and electric power steering devices, it is possible to detect an abnormality in at least one of the detection unit side communication unit and the calculation unit side communication unit.

The block diagram which shows the schematic structure about one Embodiment of an electric power steering apparatus. The perspective view which shows the disassembled perspective structure of the torque sensor about the electric power steering apparatus of embodiment. The expanded view which expanded the two yokes and the holding member on the plane about the torque sensor of the embodiment. The block diagram which shows the electrical structure of the torque sensor and control apparatus of the embodiment. (A), (b) is a graph which shows the relationship between the output value of each Hall element mounted in the torque sensor of the embodiment, and the intensity | strength of the magnetism provided. (A), (b) is a figure which shows the structure of the data stored in the register | resistor of each communication part mounted in the torque sensor of the embodiment. The sequence chart which shows each operation example of the torque sensor and control apparatus of the embodiment. The flowchart which shows the procedure of the abnormality detection process performed by CPU of the control apparatus of the embodiment. The figure which shows each operation example of the torque sensor and control apparatus of the embodiment.

  Hereinafter, an embodiment of the sensor device will be described. The sensor device of this embodiment is mounted on an electric power steering device and detects a steering torque applied to a steering mechanism of a vehicle. First, an outline of the electric power steering apparatus will be described.

  As shown in FIG. 1, the electric power steering apparatus 1 includes a steering mechanism 4 that turns a steered wheel 3 based on an operation of a driver's steering wheel 2 and an assist mechanism 5 that assists the driver's steering operation. ing.

  The steering mechanism 4 includes a steering shaft 40 that serves as a rotating shaft of the steering wheel 2. The steering shaft 40 includes a column shaft 41 connected to the center of the steering wheel 2, an intermediate shaft 42 connected to the lower end portion of the column shaft 41, and a pinion shaft 43 connected to the lower end portion of the intermediate shaft 42. . A rack shaft 45 is connected to the lower end portion of the pinion shaft 43 via a rack and pinion mechanism 44. In the steering mechanism 4, when the steering shaft 40 rotates in response to the driver's operation of the steering wheel 2, the rotational motion is converted into a reciprocating linear motion in the axial direction of the rack shaft 45 via the rack and pinion mechanism 44. The reciprocating linear motion of the rack shaft 45 in the axial direction is transmitted to the steered wheels 3 through the tie rods 46 connected to both ends thereof, whereby the steered angle of the steered wheels 3 is changed and the traveling direction of the vehicle is changed. The

  The assist mechanism 5 includes a motor 51 that is connected to the column shaft 41 via a speed reducer 50. That is, the assist mechanism 5 imparts torque to the steering shaft 40 by transmitting the rotation of the output shaft of the motor 51 to the column shaft 41 via the speed reducer 50 to assist the driver in steering operation.

  The electric power steering apparatus 1 is provided with various sensors for detecting the operation amount of the steering wheel 2 and the state amount of the vehicle. For example, the steering shaft 40 is provided with a torque sensor 7 that detects a steering torque Th applied to the steering shaft 40 when a driver performs a steering operation. The vehicle is provided with a vehicle speed sensor 8 that detects the traveling speed V thereof. The motor 51 is provided with a rotation angle sensor 9 for detecting the rotation angle θm of the output shaft. Outputs of these sensors 7 to 9 are taken into the control device 6. The control device 6 sets the current command value based on the outputs of the sensors 7 to 8 and controls the drive of the motor 51 by executing current feedback control for causing the current value supplied to the motor 51 to follow the current command value. .

Next, the structure of the torque sensor 7 will be described in detail.
As shown in FIG. 2, the column shaft 41 has an input shaft 47 connected to the steering wheel 2 and a lower shaft 48 connected to the intermediate shaft 42 connected on the same axis m via a torsion bar 49. Consists of structure. That is, torsional deformation occurs in the torsion bar 49 when the steering torque Th applied to the input shaft 47 in accordance with the operation of the steering wheel 2 is transmitted from the input shaft 47 to the lower shaft 48. At this time, a relative rotational displacement corresponding to the steering torque Th is generated between the input shaft 47 and the lower shaft 48.

The torque sensor 7 includes a cylindrical holding member 70 and annular first and second yokes 71 and 72 arranged around the holding member 70 with a predetermined gap therebetween.
On the outer peripheral surface of the holding member 70, a multipolar magnet 73 is provided in which magnetic poles of N and S poles are alternately arranged in the circumferential direction. The holding member 70 is externally fitted to the lower end portion of the input shaft 47. That is, the holding member 70 rotates integrally with the input shaft 47.

  The first yoke 71 and the second yoke 72 are fixed to the lower shaft 48 via a connection structure (not shown). That is, the first yoke 71 and the second yoke 72 rotate integrally with the lower shaft 48. The first yoke 71 and the second yoke 72 are arranged to face each other with a predetermined gap in a direction parallel to the axis m. A plurality of claw portions 71 a extending toward the second yoke 72 are formed on the inner peripheral surface of the first yoke 71. A plurality of claw portions 72 a extending toward the first yoke 71 are formed on the inner peripheral surface of the second yoke 72. FIG. 3 is a developed view in which the holding member 70 and the first and second yokes 71 and 72 are developed on a plane. As shown in FIG. 3, the claw portions 71a and 72a of the first and second yokes 71 and 72 are alternately arranged in the circumferential direction and face the multipolar magnet 73 with a predetermined gap therebetween. .

  As shown in FIG. 2, the torque sensor 7 has an annular first magnetism collecting ring 74 disposed around the first yoke 71 with a predetermined gap therebetween, and a predetermined gap around the second yoke 72. An annular second magnetism collecting ring 75 is provided so as to be spaced apart. Each of the magnetism collecting rings 74 and 75 is made of a magnetic material. As shown in the enlarged view in the drawing, the first and second magnetism collecting rings 74 and 75 are arranged on the magnetism collecting portions 74a and 75a facing each other with a predetermined gap in a direction parallel to the axis m. , And magnet collectors 74b and 75b are provided. The first Hall IC 10 and the second Hall as a detection unit that outputs a detection signal according to the strength of the applied magnetism (magnetic field) between the magnetic collection units 74a and 75a and between the magnetic collection units 74b and 75b. IC20 is each arrange | positioned.

  In the torque sensor 7, when a relative rotational displacement occurs between the input shaft 47 and the lower shaft 48 due to the steering torque Th input to the input shaft 47, the positional relationship between the holding member 70 and the yokes 71 and 72 is determined. As a result, the magnetism collected by the yokes 71 and 72 changes. As a result, the intensity of magnetism applied to the Hall ICs 10 and 20 changes, and a detection signal corresponding to the twist angle of the torsion bar 49 is output from each Hall IC 10 and 20.

Next, the electrical configuration of the torque sensor 7 and the control device 6 will be described.
As shown in FIG. 4, the first Hall IC 10 includes a first magnetic detection unit 11 and a second magnetic detection unit 12. The first magnetic detection unit 11 includes a first Hall element 11a as a magnetic detection element. As shown in FIG. 5A, the first Hall element 11a outputs an analog signal (voltage signal) having a positive correlation with the applied magnetic strength. As shown in FIG. 4, the analog signal output from the first Hall element 11a is amplified through an amplifier 11b, then taken into an A / D converter 11c, quantized with a predetermined number of bits, and converted into a digital signal. Is done. The first magnetic detection unit 11 outputs the digital signal converted by the A / D converter 11c as the first detection signal S1. The second magnetic detection unit 12 includes a second Hall element 12a. As shown in FIG. 5B, the second Hall element 12a outputs an analog signal having a reverse correlation with the first Hall element 11a, that is, a negative correlation with the applied magnetic strength. . As shown in FIG. 4, the analog signal output from the second Hall element 12a is amplified through the amplifier 12b, then taken into the A / D converter 12c, quantized with a predetermined number of bits, and converted into a digital signal. Is done. The second magnetic detection unit 12 outputs the digital signal converted by the A / D converter 12c as the second detection signal S2.

  The second Hall IC 20 includes a third magnetic detector 21 having the same structure as the first magnetic detector 11 and a fourth magnetic detector 22 having the same structure as the second magnetic detector 12. That is, the third magnetic detection unit 21 includes a third Hall element 21a that performs the same output as the first Hall element 11a, an amplifier 21b, and an A / D converter 21c. The fourth magnetic detection unit 22 includes a fourth Hall element 22a that performs the same output as the second Hall element 12a, an amplifier 22b, and an A / D converter 22c. The third magnetic detection unit 21 outputs the digital signal converted by the A / D converter 21c as the third detection signal S3. The fourth magnetic detection unit 22 outputs the digital signal converted by the A / D converter 22c as the fourth detection signal S4.

  The torque sensor 7 includes a first communication unit 13 and a second communication unit 23 that can perform bidirectional communication with the control device 6. The first communication unit 13 and the second communication unit 23 have registers 13a and 23a, respectively. When the first communication unit 13 takes in the detection signal S1 output from the first magnetic detection unit 11 and the detection signal S2 output from the second magnetic detection unit 12, each detection is performed as illustrated in FIG. The digital values of the signals S1 and S2 are sequentially stored in the register 13a. The first communication unit 13 generates a first torque detection signal St1 including a digital value stored in the register 13a in response to a transmission request from the control device 6, and sends the first torque detection signal St1 to the control device 6. Send. When the second communication unit 23 takes in the detection signal S3 output from the third magnetic detection unit 21 and the detection signal S4 output from the fourth magnetic detection unit 22, each detection is performed as illustrated in FIG. The digital values of the signals S3 and S4 are sequentially stored in the register 23a. The second communication unit 23 generates a second torque detection signal St2 including a digital value stored in the register 23a in response to a transmission request from the control device 6, and sends the second torque detection signal St2 to the control device 6. Output.

  As shown in FIG. 4, the control device 6 stores a first communication unit 60 and a second communication unit 61 that can perform bidirectional communication with the torque sensor 7, a control program, an arithmetic map, and the like. A ROM 62 and a CPU (Central Processing Unit) 63 that performs various arithmetic processes are included.

  The first communication unit 60 includes a register 60a. When the first communication unit 60 receives the first torque detection signal St1 transmitted from the torque sensor 7, the digital value is stored in the register 60a. Then, in response to a request from the CPU 63, the first communication unit 60 outputs the digital value of the first torque detection signal St1 stored in the register 60a to the CPU 63. The second communication unit 61 also includes a register 61a. When the second torque detection signal St2 transmitted from the torque sensor 7 is received, the digital value is stored in the register 61a. Then, in response to a request from the CPU 63, the second communication unit 61 outputs the digital value of the second torque detection signal St2 stored in the register 61a to the CPU 63.

  The CPU 63 makes a transmission request for the first torque detection signal St1 and the second torque detection signal St2 to the torque sensor 7 through the first communication unit 60 and the second communication unit 61, respectively, in a predetermined cycle. As a result, the CPU 63 acquires the torque detection signals St1, St2 at a predetermined cycle. The CPU 63 acquires the respective digital values of the first detection signal S1 and the second detection signal S2 based on the first torque detection signal St1, and the third detection signal S3 and the fourth detection signal based on the second torque detection signal St2. Each digital value of S4 is acquired. The CPU 63 calculates the output values of the hall elements 11a, 12a, 21a, and 22a based on the acquired digital values of the detection signals S1 to S4, and the twist angle of the torsion bar 49 based on at least one of the calculated values. Is calculated. Specifically, the ROM 62 stores in advance an arithmetic map indicating a correspondence relationship between the output values of the hall elements 11a, 12a, 21a, and 22a and the twist angle of the torsion bar 49. For example, the CPU 63 calculates the torsion angle of the torsion bar 49 from the output calculation value of the first hall element 11a based on the calculation map stored in the ROM 62, and multiplies the calculated torsion angle by the spring constant of the torsion bar 49. A steering torque detection value is calculated.

Next, an abnormality detection method for the torque sensor 7 by the CPU 63 will be described.
When both the first Hall IC 10 and the second Hall IC 20 are normal, the CPU 63 detects an abnormality based on the output calculation values of the Hall elements 11a, 12a, 21a, and 22a. Specifically, as shown in FIGS. 5A and 5B, the output values of the first Hall element 11a and the second Hall element 12a have an inverse correlation, and therefore, the addition of these output values is performed. The value is ideally a constant value. Using this, the CPU 63 adds the respective output calculation values of the first hall element 11a and the second hall element 12a, and when the added value is out of a predetermined range, the first hall element 11a and the second hall element 12a. It is determined that an abnormality has occurred in either one. Similarly, the CPU 63 adds the respective output calculation values of the third hall element 21a and the fourth hall element 22a, and when the added value is out of the predetermined range, either of the third hall element 21a or the fourth hall element 22a. It is determined that an abnormality has occurred on either side.

  When the CPU 63 detects an abnormality in one of the first Hall IC 10 and the second Hall IC 20 by the abnormality determination method as described above, the CPU 63 calculates the steering torque Th using only the Hall IC in which no abnormality is detected. continue. Further, the CPU 63 continues the abnormality detection only for the Hall IC in which no abnormality is detected. Details thereof will be described with reference to FIGS. 7 and 8, it is assumed that an abnormality is detected in the second Hall IC 20 and the normal Hall IC is only the first Hall IC 10.

  As shown in FIG. 7, after the torque sensor 7 transmits the first torque detection signal St1 to the control device 6 (S10), the CPU 63 takes in the first torque detection signal St1 output from the torque sensor 7 (S20). The CPU 63 inverts all the bit data of the first torque detection signal St1 to generate a digital value for check (S21). Next, the CPU 63 generates a check signal Sc including the check digital value (S22), and determines whether or not the transmission period of the check signal Sc is reached (S23). When the CPU 63 determines that it is the transmission cycle of the check signal Sc (S23: YES), the CPU 63 transmits the check signal Sc to the torque sensor 7 (S24). Thereafter, the CPU 63 calculates the output value of each Hall element 11a, 12a based on the first torque detection signal St1 (S25), and the abnormality detection process for each Hall element 11a, 12a based on the added value of these calculated values. (S26). Further, the CPU 63 calculates a steering torque detection value based on the output calculation value of the first hall element 11a or the output calculation value of the second hall element 12a (S27).

  When receiving the check signal Sc transmitted from the control device 6 (S11), the first communication unit 13 of the torque sensor 7 stores the check digital value included in the check signal Sc in the register 13a (S12). Next, the first communication unit 13 generates an abnormality diagnosis signal Se including the check digital value stored in the register 13a (S13), and transmits the abnormality diagnosis signal Se to the control device 6 (S14). Thereafter, the first communication unit 13 takes in the detection signals S1 and S2 output from the first Hall IC 10 (S15) and stores their digital values in the register 13a (S16). And the 1st communication part 13 produces | generates the 1st torque detection signal St1 containing the digital value stored in the register | resistor 13a (S17), and transmits this to the control apparatus 6 (S18). That is, when the first communication unit 13 receives the check signal Sc transmitted from the control device 6, the first communication unit 13 sequentially transmits the abnormality diagnosis signal Se and the first torque detection signal St1 to the control device 6.

  When receiving the abnormality diagnosis signal Se transmitted from the torque sensor 7 via the first communication unit 60 (S28), the CPU 63 of the control device 6 performs an abnormality detection process based on the abnormality diagnosis signal Se (S29). Specifically, as shown in FIG. 8, the CPU 63 determines whether or not the check digital value included in the abnormality diagnosis signal Se matches the original value (S40). When the check digital value included in the abnormality diagnosis signal Se does not match the original value (S40: NO), the CPU 63 determines whether the first communication unit 13 of the torque sensor 7 and the first communication unit 60 of the control device 6 It is determined that an abnormality has occurred in at least one (S41). On the other hand, when the check digital value included in the abnormality diagnosis signal Se matches the original value (S40: YES), the first communication unit 13 of the torque sensor 7 and the first communication unit 60 of the control device 6 are used. Is determined to be normal (S42).

  Then, as shown in FIG. 7, the CPU 63 determines whether or not an abnormality is detected in at least one of the abnormality detection processes of S26 and S29 (S30). If the CPU 63 detects an abnormality in at least one of these abnormality detection processes (S30: YES), the CPU 63 performs fail-safe control such as stopping the motor 51, for example, to ensure the safety of the electric power steering device 1. Execute (S31). On the other hand, when an abnormality cannot be detected (S30: NO), after the first torque detection signal St1 transmitted from the torque sensor 7 is captured via the first communication unit 13 (S32), S21 and thereafter The same process is performed.

Note that the CPU 63 executes the processing according to FIGS. 7 and 8 even when an abnormality is detected in the first Hall IC 10 and the normal Hall IC is only the second Hall IC 20.
According to such a structure, the effect | action and effect shown to the following (1)-(5) can be acquired.

  (1) As shown in FIG. 9, for example, in the first communication unit 13 of the torque sensor 7, one bit in the area where the digital value of the first detection signal S <b> 1 of the register 13 a is stored is fixed to “0”. Suppose an abnormality occurs. At this time, when the digital value of the first detection signal S1 is stored in the register 13a, the digital value stored in the register 13a is “0001” even though the original digital value is “0101. "..." and an abnormal value. At this time, the first communication unit 13 of the torque sensor 7 generates the first torque detection signal St1 based on the digital value stored in the register 13a, and transmits this to the control device 6. Therefore, when the CPU 63 acquires the digital value of the first detection signal S1 from the first torque detection signal St1, and calculates the output value of the first Hall element 11a based on the digital value, the calculated value becomes an abnormal value. In this case, it is sufficient that an abnormality can be detected based on the added value of the respective output calculation values of the first Hall element 11a and the second Hall element 12a. However, if the added value is within a normal range, the abnormality may not be detected. is there.

  In this regard, the CPU 63 of the present embodiment generates a check digital value including bit data “1110...” By inverting the bit data of the first torque detection signal St1, and includes the check digital value. A check signal Sc is transmitted to the torque sensor 7. When the check signal Sc is received by the first communication unit 13 of the torque sensor 7, the first communication unit 13 stores the check digital value included in the check signal Sc in the register 13a. At this time, the check digital value is stored in the register 13a with erroneous bit data “1010...” Due to an abnormality of the register 13a. Then, the first communication unit 13 generates an abnormality diagnosis signal Se based on the erroneous digital value for checking stored in the register 13 a and transmits it to the control device 6. In this case, when the CPU 63 compares the check digital value “1010...” Included in the abnormality diagnosis signal Se with the original value “1110...” Of the check digital value, the values do not match. Therefore, the CPU 63 can detect an abnormality.

  Thus, according to the CPU 63 of the present embodiment, it is possible to detect an abnormality in the register 13a in the first communication unit 13 of the torque sensor 7. In addition to the abnormality of the register 13a, the first communication unit 13 of the torque sensor 7 erroneously transmits the first torque detection signal St1, or the first communication unit 60 of the control device 6 erroneously transmits the first torque detection signal St1. A received abnormality can be detected in the same manner. Further, if the CPU 63 transmits a check signal Sc to the second communication unit 23 of the torque sensor 7, the abnormality of the second communication unit 23 of the torque sensor 7 and the abnormality of the second communication unit 61 of the control device 6 are similarly detected. Can do.

  (2) When only the first Hall IC 10 is normal, the torque sensor 7 alternately outputs the first torque detection signal St1 and the abnormality diagnosis signal Se based on the check signal Sc transmitted from the control device 6. When only the second Hall IC 20 is normal, the torque sensor 7 alternately outputs the second torque detection signal St2 and the abnormality diagnosis signal Se based on the check signal Sc transmitted from the control device 6. As a result, the CPU 63 can perform abnormality detection based on the abnormality diagnosis signal Se while calculating the steering torque detection value based on the first torque detection signal St1 or the second torque detection signal St2. High reliability can be ensured while satisfying.

  (3) The torque sensor 7 transmits an abnormality diagnosis signal Se and torque detection signals St1, St2 based on reception of the check signal Sc. Thus, the CPU 63 can acquire not only the abnormality diagnosis signal Se but also the torque detection signals St1 and St2 simply by transmitting the check signal Sc to the torque sensor 7, so that the CPU 63 detects the torque detection signal to the torque sensor 7. There is no need to make a transmission request for St1 and St2. Therefore, the communication time between the CPU 63 and the torque sensor 7 can be shortened.

  (4) In the first Hall IC 10, the first Hall element 11 a that detects the magnetic strength between the magnetic flux collectors 74 a and 75 a and outputs an output having an inverse correlation with the magnetic strength. The second Hall element 12a is provided. Thus, if the CPU 63 calculates the respective output values of the first hall element 11a and the second hall element 12a based on the first torque detection signal St1 output from the torque sensor 7, those added values are out of the predetermined range. Accordingly, the abnormality of each Hall element 11a, 12a can be detected. Similarly, the CPU 63 can detect abnormalities in the hall elements 21a and 22a of the second hall IC 20.

  (5) When the abnormality is detected in one of the first Hall IC 10 and the second Hall IC 20, that is, when there is only one normal Hall IC, the CPU 63 determines that the Hall IC has no abnormality detected. On the other hand, in addition to the abnormality detection based on the output calculation value of the Hall element, the abnormality detection based on the check signal Sc is performed. By performing two types of abnormality detection in this way, it is possible to detect an abnormality more reliably, so that the reliability of the torque sensor 7 can be maintained high even in a situation where there is only one normal Hall IC. it can. As a result, the electric power steering apparatus 1 can apply a more appropriate assist force to the steering mechanism 4.

In addition, the said embodiment can also be implemented with the following forms.
In the above embodiment, the first communication unit 13 of the torque sensor 7 has a structure including the register 13a. However, the first communication unit 13 and the register 13a may be separate. The same applies to the second communication unit 23 of the torque sensor 7 and the communication units 60 and 61 of the control device 6.

  In the above embodiment, the outputs of the first Hall element 11a and the second Hall element 12a have an inverse correlation with the magnetic strength, but the first Hall element 11a and the second Hall element The element 12a may output the same correlation with the magnetic strength. In this case, for example, the abnormality of the first Hall element 11a and the second Hall element 12a may be detected based on whether or not the respective output calculation values of the first Hall element 11a and the second Hall element 12a match. . The same configuration may be adopted for the third Hall element 21a and the fourth Hall element 22a. The point is that any abnormality may be detected as long as the correlation between the output values of the Hall elements 11a, 12a, 21a, and 22a is utilized.

  In the above embodiment, the check digital value is generated by inverting the bit data of the first torque detection signal St1 and the second torque detection signal St2, but the check digital value can be changed as appropriate. For example, a digital value for checking may be one in which all bit data is set to “0”, or one in which all bit data is set to “1”. For example, if a check digital value in which all bit data is set to “0” is used, the digital value is set to “1” in each communication unit 13, 23 of the torque sensor 7 or each communication unit 60, 61 of the control device 6. Abnormalities that stick can be detected. Further, if a check digital value in which all bit data is set to “1” is used, the digital value is set to “0” in each of the communication units 13 and 23 of the torque sensor 7 or each of the communication units 60 and 61 of the control device 6. Abnormalities that stick can be detected. Therefore, it is possible to obtain the same effect as the above embodiment.

  In the above embodiment, the torque sensor 7 transmits the abnormality diagnosis signal Se and the torque detection signals St1, St2 based on the reception of the check signal Sc. Instead, the torque sensor 7 transmits the abnormality diagnosis signal Se based on the reception of the check signal Sc, and transmits the torque detection signals St1, St2 based on the reception of the trigger signal different from the check signal Sc. Good. According to such a configuration, the CPU 63 appropriately adjusts the timing for transmitting the check signal Sc to the torque sensor 7 and the timing for transmitting the trigger signal, thereby adjusting the acquisition timing of the abnormality diagnosis signal Se and the torque detection signals St1, St2. It can be set arbitrarily.

  -The number of the magnetic detection parts provided in each Hall IC10 and 20 is not restricted to two, You may change suitably. When only one magnetic detection unit is provided in each Hall IC 10, 20, for example, only the first magnetic detection unit 11 is provided in the first Hall IC 10 and only the third magnetic detection unit 21 is provided in the second Hall IC 20. In this case, the abnormality of the first Hall element 11a and the third Hall element 21a may be detected based on whether or not the respective output calculation values of the first Hall element 11a and the third Hall element 21a match.

  In the above embodiment, the abnormality detection based on the sum of the output calculation values of the first Hall element 11a and the second Hall element 12a, and the output calculation values of the third Hall element 21a and the fourth Hall element 22a Although the abnormality detection based on the added value is performed, only the abnormality detection based on the check signal Sc and the abnormality diagnosis signal Se may be performed.

  In the above embodiment, the first torque detection signal St1 and the abnormality diagnosis signal Se are alternately output, and the second torque detection signal St2 and the abnormality diagnosis signal Se are alternately output. It is not limited to such an embodiment. For example, the check digital value included in the check signal Sc together with the digital value of each of the detection signals S1 and S2 may be stored in the register 13a, and a signal including these digital values may be transmitted to the control device 6. In this case, the first torque detection signal St1 and the abnormality diagnosis signal Se in the above embodiment are transmitted to the control device 6 at the same time. Similarly, the check digital value included in the check signal Sc together with the digital value of each of the detection signals S3 and S4 may be stored in the register 23a, and a signal including these digital values may be transmitted to the control device 6.

In the above embodiment, the torque sensor 7 is provided with the two Hall ICs 10 and 20, but either one of them may be omitted.
The configuration of the above embodiment is not limited to the torque sensor 7 and can be applied to an appropriate sensor device such as a rotation angle sensor. In short, if the sensor device includes a detection unit that transmits a detection signal corresponding to a physical quantity as a digital signal and a calculation unit that executes a calculation based on the detection signal transmitted from the detection unit, the configuration of the above embodiment is adopted. Is possible.

  Sc ... Check signal, Se ... Abnormality diagnosis signal, St1, St2 ... Torque detection signal, 1 ... Electric power steering device, 4 ... Steering mechanism, 7 ... Torque sensor, 11, 12, 21, 22 ... Magnetic detection unit, 11a, 12a, 21a, 22a ... Hall element (detection element), 13, 23 ... Communication unit (detection unit side communication unit), 13a, 23a ... Register, 51 ... Motor, 60, 61 ... Communication unit (calculation unit side communication unit) , 60a, 61a ... registers, 63 ... CPU (arithmetic unit).

Claims (4)

A detection unit that transmits a detection signal corresponding to the detected physical quantity from the detection unit side communication unit as a digital signal;
In a sensor device comprising: a detection unit that receives the detection signal transmitted from the detection unit via a calculation unit side communication unit, and executes a calculation based on the detection signal;
The calculation unit transmits a check signal including a check digital value based on reception of the detection signal to the detection unit via the calculation unit side communication unit,
When the detection unit receives the check signal via the detection unit side communication unit, the detection unit generates an abnormality diagnosis signal based on the check digital value included in the check signal, and the abnormality diagnosis signal is transmitted to the detection unit side. Transmitted from the communication unit to the calculation unit,
When the abnormality diagnostic signal transmitted from the detection unit is received via the arithmetic unit side communication unit, the arithmetic unit receives the check digital value included in the abnormality diagnostic signal and the source of the check digital value A sensor device that detects an abnormality in at least one of the detection unit side communication unit and the calculation unit side communication unit based on a comparison with a value of the value. The sensor device according to claim 1,
The detection unit transmits the abnormality diagnosis signal and the detection signal based on reception of the check signal. The sensor device according to claim 1 or 2,
The detection unit includes a plurality of detection elements that detect the same physical quantity and perform outputs that have a correlation with the physical quantity, and output a digital signal that includes output values of the plurality of detection elements as the detection signal. Is what you send as
The sensor unit further detects an abnormality of the detection element based on a correlation between output values of the plurality of detection elements. A motor for applying assist force to the steering mechanism of the vehicle;
A torque sensor for detecting a steering torque applied to the steering mechanism,
In the electric power steering apparatus that controls the driving of the motor based on the steering torque detected by the torque sensor,
The electric power steering apparatus characterized by using the sensor apparatus as described in any one of Claims 1-3 as said torque sensor.