JP2013079885A - Rotational angular velocity sensor or rotational angular acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotational angular velocity sensor or rotational angular acceleration sensor capable of improving detection accuracy.SOLUTION: A rotational angular velocity sensor 1 includes a first strain sensor 11a provided on one side in a rotation direction of a strain amount detection piece (a beam 104), and a second strain sensor 11b provided on the other side in the rotation direction of the strain amount detection piece. A rotational angular velocity ω of a rotor is detected on the basis of output signals of the first strain sensor 11a and the second strain sensor 11b representing a length variation in a radial direction of the strain amount detection piece, caused by centrifugal force acting on the strain amount detection piece accompanying rotation of the rotor (a body 100). The rotational angular acceleration sensor 1 detects a rotational angular acceleration dω of the rotor on the basis of a difference between the output signal of the first strain sensor 11a, and the output signal of the second strain sensor 11b when the first strain sensor 11a and the second strain sensor 11b respectively detects bending in an extending direction and bending in a contracting direction by bending of the strain amount detection piece.

Description

  The present invention relates to a rotational angular velocity sensor or a rotational angular acceleration sensor.

  Conventionally, a rotation angular velocity sensor that detects a rotation angular velocity of a rotating body or a rotation angular acceleration sensor that detects a rotation angular acceleration of a rotating body is known. For example, a rotational angular velocity sensor disclosed in Patent Document 1 is applied to a power steering device of an automobile and detects a steering speed.

JP 2010-215047 A

  However, the conventional rotational angular velocity sensor estimates the steering speed by differentiating the steering angle. The estimated steering speed is obtained by performing a calculation process called differentiation on the steering angle, which is a physical quantity, and is a pseudo value or an approximate value that is treated as a steering speed equivalent value (not a physical quantity itself). Therefore, there has been a problem that there is a limit in improving detection accuracy. The same can be said for the conventional rotational angular acceleration sensor because the steering acceleration is obtained by further differentiating the steering speed obtained as described above. An object of the present invention is to provide a rotational angular velocity sensor or a rotational angular acceleration sensor that can improve detection accuracy.

In order to achieve the above object, the rotational angular velocity sensor of the present invention is preferably provided on the other side in the rotation direction of the strain amount detection piece and the first strain sensor provided on one side in the rotation direction of the strain amount detection piece. A second strain sensor, and a first strain sensor and a second strain sensor, each of which is a radial length change amount of the strain amount detection piece due to a centrifugal force acting on the strain amount detection piece as the rotating body rotates. The rotational angular velocity of the rotating body is detected based on the output signal.
The rotational angular acceleration sensor of the present invention is preferably a first strain sensor provided on one side in the rotational direction of the strain amount detection piece and a second strain sensor provided on the other side in the rotational direction of the strain amount detection piece. And when each of the first strain sensor and the second strain sensor detects bending in the extension direction and bending in the contraction direction by bending of the strain amount detection piece, the output signal of the first strain sensor and the second strain sensor The rotational angular acceleration of the rotating body is detected based on the difference between the sensor output signals.

  Therefore, the detection accuracy can be improved because the rotational angular velocity or the rotational angular acceleration of the rotating body is detected without using the differential operation processing of the angle.

1 is a system configuration diagram of a power steering apparatus to which a rotational angular velocity sensor or a rotational angular acceleration sensor is applied. It is a disassembled perspective view which shows the state in which a sensor unit is installed in a pinion shaft. It is an axial front view of a sensor unit. FIG. 4 is a partial cross-sectional view of the sensor unit (II cross-sectional view of FIG. 3). It is the schematic of the assembly of a strain sensor. It is a circuit diagram showing the Wheatstone bridge circuit of a strain sensor. It is a figure which shows the relationship between the resistance of a strain sensor, the shape of dummy resistance, and the crystal orientation of a silicon substrate. It is a figure which shows the relational characteristic of the output signal (strain amount A, B) of a strain sensor, and rotational angular velocity (omega). It is a figure which shows the relational characteristic of the output signal (distortion amount A, B) of the distortion sensor at the time of disturbance input, and rotational angular velocity (omega). It is a figure which shows the relational characteristic of the output signal (strain amount A, B) of a strain sensor, and rotational angular acceleration domega.

  Hereinafter, embodiments for realizing the rotational angular velocity sensor or the rotational angular acceleration sensor of the present invention will be described with reference to the drawings.

[Example 1]
In the first embodiment, a rotational angular velocity sensor will be described.
FIG. 1 is a system configuration diagram of a power steering apparatus to which the rotational angular velocity sensor of the first embodiment is applied. A vehicle steering apparatus to which the power steering apparatus of the first embodiment is applied has an operation mechanism, a gear mechanism, and a link mechanism. The operation mechanism has a steering wheel SW and a steering shaft (column shaft) SS. The steering shaft SS includes a first shaft S1 and a second shaft S2 (intermediate shaft). The gear mechanism is of a rack and pinion type and has a rack R and a pinion P. The pinion P is provided at the tip of the pinion shaft PS connected to the second shaft S2 and meshes with the rack R. The link mechanism has a tie rod TR connected to both ends of a rack shaft RS provided with a rack R, and steered wheels FL and FR connected to the tie rod TR.

  The power steering device is electric (hereinafter referred to as EPS). The EPS is an electric direct connection type in which the electric motor 3 directly drives gears to generate an auxiliary force, and is a pinion assist type that is attached to the pinion shaft PS and applies auxiliary power to the rotation of the pinion shaft PS. The EPS includes a motor 3 driven by electric power (current) supplied from a battery BATT as a power source, a reduction gear mechanism 4 that decelerates the rotation of the motor 3, and a torque sensor as steering torque detection means that detects steering torque. TS, a rotation angular velocity sensor 1 as a steering angular velocity detection means for detecting the rotation angular velocity ω of the pinion shaft PS as a steering angular velocity, and a resolver as a motor rotation detection means for detecting the rotation (rotation angle or rotation position) of the motor 3 And an electronic control unit ECU serving as a steering assist control device for controlling the driving of the motor 3 in response to input of signals from the detection means. The pinion shaft PS, the rack shaft RS, the reduction gear mechanism 4, and the torque sensor TS are accommodated in the housing HSG and constitute a single gear unit. The motor 3 and the electronic control unit ECU are attached to this gear unit, and the EPS is configured as an electromechanical integrated EPS unit.

  The reduction gear mechanism is a worm gear mechanism having a worm shaft provided on the output shaft of the motor 3 and a worm wheel WW that meshes with the worm shaft. The worm wheel WW is provided coaxially with the pinion shaft PS and rotates integrally with the pinion P. At the steering assist time, the driving force of the motor 3 is transmitted to the pinion P through the reduction gear mechanism. In the pinion shaft PS, a torque sensor TS is provided on the second shaft S2 side of the worm wheel WW and is connected to the ECU. In the pinion shaft PS, the rotational angular velocity sensor 1 is provided on the second shaft S2 side of the torque sensor TS and outside the housing HSG, and is connected to the ECU.

  When the steering wheel SW is steered by the driver, the steering torque input to the pinion shaft PS via the steering shaft SS is detected by the torque sensor TS and output to the ECU. Further, a vehicle speed signal from a vehicle speed sensor (not shown) is input to the ECU. Further, the rotational angular velocity (steering angular velocity) transmitted to the pinion shaft PS via the steering shaft SS is detected by the rotational angular velocity sensor 1 and output to the ECU. The ECU calculates a basic steering assist amount (target steering assist force) based on the input steering torque and vehicle speed, and applies the motor steering position to the motor 3 based on signals such as the target steering assist force and the input motor rotation position. A drive current is output and the operation of the motor 3 is controlled. When the ECU controls the current (drive current) flowing through the motor 3, an appropriate auxiliary power is given to the rotation of the pinion shaft PS, and the pinion P drives the rack R to move in the axial direction. A person's steering force is assisted. Further, the ECU corrects the steering assist amount (drive signal of the motor 3) based on the input rotational angular velocity ω, and performs control for improving steering operability and steering feeling. For example, taking into account the inertia, viscosity, friction, etc. of the steering device, improving the steering feeling by performing inertia compensation, viscosity compensation, etc., which correct the steering assist amount with the compensation value created based on the detected value of the rotational angular velocity ω Plan. The content of this compensation control is a well-known technique and will not be described.

  FIG. 2 is an exploded perspective view showing a state in which the sensor unit 10 of the rotational angular velocity sensor 1 is installed on the pinion shaft PS. Hereinafter, for the sake of explanation, the x-axis is set in the direction in which the pinion shaft PS extends, and the side where the pinion shaft PS is connected to the second shaft S2 is the positive direction. The rotational angular velocity sensor 1 is configured as a sensor unit 10 in which a sensor body (strain sensor 11) and a transmission-side antenna 12 are integrally assembled with a body 100. The body 100 is a substantially annular member, and is fitted and installed on the outer periphery of the positive end of the pinion shaft PS protruding from the positive end of the x axis of the housing HSG. A hole 101 is formed through the body 100 so as to extend in the axial direction. A plurality of axial grooves are formed in the hole 101 (spline processing), and the body 100 is provided so as to be fitted to the spline at the end in the x-axis positive direction of the pinion shaft PS. The body is a rotating body that is integrally coaxial with the pinion shaft PS and rotates integrally with the pinion shaft PS. A plurality (four in the first embodiment) of strain sensors 11 are installed on the inner peripheral side of the body 100 as described later. An antenna 12 is installed on an end surface of the body 100 on the housing HSG side (x-axis negative direction side) so as to surround the hole 101. The antenna 12 is connected to the strain sensor 11, functions as a transmitting antenna that receives an input of a signal detected by the strain sensor 11 and transmits the signal to a receiving antenna unit 20 described later, and receives power from the receiving antenna unit 20. The power receiving coil functions as a power receiving coil that receives the power supplied to the strain sensor 11.

  The receiving-side antenna unit 20 has a substantially annular shape, and is installed in the opening at the end in the positive x-axis direction of the housing HSG so as to surround the pinion shaft PS. An antenna 21 is installed on the end surface on the x-axis positive direction side of the reception-side antenna unit 20 so as to surround the pinion shaft PS. The antenna 21 is connected to the ECU via a connection line 200, functions as a receiving antenna that receives a signal transmitted from the strain sensor 11 and sends the signal to the ECU, and receives power supplied from the ECU. Functions as a power feeding coil that sends the sensor unit 10 to the sensor unit 10. In a state where the sensor unit 10 is installed on the pinion shaft PS and the receiving-side antenna unit 20 is installed on the housing HSG, the antennas 12 and 21 are provided so as to face each other in the x-axis direction.

  Hereinafter, the central axis (rotation center) of the sensor unit 10 (body 100) is referred to as an axis O. FIG. 3 is an axial front view of the sensor unit 10 as viewed from the direction in which the axis O extends. FIG. 4 is a side view of the sensor unit 10 as viewed from a direction perpendicular to the axis O and shows a partial cross section (a cross section taken along the line II in FIG. 3). Note that illustration of the antenna 12 is omitted in FIGS. 3 and 4. The body 100 is formed with a female screw hole 104 that penetrates the body 100 in the radial direction, and a screw 14 for fastening and fixing the body 100 to the pinion shaft PS is screwed into the female screw hole 104. On the inner peripheral side (hole 101) of the body 100, recesses 102 and 103 are provided at two locations facing each other across the axis O so as to fall in the outer diameter direction (direction away from the axis O). Beams 104 and 105 projecting from the bottom of the recesses 102 and 103 in the inner diameter direction (direction toward the axis O) are provided at substantially central positions in the circumferential direction (around the axis O) of the recesses 102 and 103, respectively. One beam 104 is a strain amount detection piece, and the other beam 105 is a counter piece.

  As shown in FIG. 3, the beam 104 is provided at a position spaced apart from the axis O of the body 100 by a predetermined distance in the radial direction, and is provided so as to extend on a radial straight line passing through the axis O. That is, the longitudinal direction of the beam 104 (when viewed from the direction of the axis O) is provided so as to substantially coincide with the radial direction of the body 100. The beam 104 is formed in a plate shape, and its circumferential dimension (plate thickness) is smaller than the radial dimension (plate width). As shown in FIG. 4, the beam 104 is provided over the entire range of the body 100 in the axial direction, and the axial dimension thereof is larger than the radial dimension. The beam 104 has a predetermined mass so that a centrifugal force acts with the rotation of the body 100, and is slightly shrunk (distorted) in the outer diameter direction by the action of the centrifugal force, so that its radial dimension is reduced. ing. The beam 105 is provided on the opposite side of the beam 104 with respect to the axis O (symmetrical with respect to the axis O) in the same shape as the beam 104. That is, the beam 105 is provided in a plate shape whose longitudinal direction (when viewed from the direction of the axis O) substantially coincides with the radial direction of the body 100, and centrifugal force acts as the body 100 rotates. Are formed so that the radial dimension is reduced by the action of the centrifugal force.

  The sensor body is composed of a strain sensor 11 (first to fourth strain sensors 11a to 11d) as means for detecting the strain amount of the structure for detecting the strain amount (beams 104 and 105). When the direction in which the body 100 rotates (the direction of the arrow α in FIG. 3) is the “rotating direction”, the first strain sensor 11a is provided on the surface on one side of the rotating direction of the one beam 104. The first strain sensor 11a detects the strain amount A1 of the beam 104 on one side in the rotational direction. A second strain sensor 11b is provided on the other side of the beam 104 in the rotational direction. The second strain sensor 11b detects the strain amount B1 on the other side of the beam 104 in the rotational direction. A third strain sensor 11c is provided on one side in the rotational direction of the other beam 105. The third strain sensor 11c detects the strain amount A2 of the beam 105 on one side in the rotational direction. A fourth strain sensor 11d is provided on the other side of the beam 105 in the rotational direction. The fourth strain sensor 11d detects the strain amount B2 on the other side of the beam 105 in the rotational direction. The first and second strain sensors 11a and 11b are disposed at substantially the center of the beam 104 in the radial direction and the x-axis direction of the body 100. The first and second strain sensors 11a and 11b are disposed substantially symmetrically with the beam 104 interposed therebetween (so that the surfaces of the beam 104 to which one strain sensor 11 is attached overlap each other when viewed from the front). Similarly, the third and fourth strain sensors 11c and 11d are arranged in the center of the beam 105 in the radial direction and the x-axis direction of the body 100, and overlap with both sides of the beam 105 in the direction around the axis O. Is provided.

[Configuration of strain sensor]
Here, details of the strain sensor 11 will be described. FIG. 5 is a schematic diagram showing the configuration of the assembly 110 of the strain sensor 11. This assembly 110 includes a Wheatstone bridge circuit 112 having a resistor 112a and a dummy resistor 112b on the same silicon substrate 111, a strain sensor amplifier group 113, an analog / digital converter 114, a rectification / detection / modulation / demodulation circuit unit 115, a communication A control unit 116, an electrode pad 118 for external connection, and an adhesive unit 117 are provided. The silicon substrate 111 is formed of a silicon single crystal. Hereinafter, the silicon substrate 111 and the thin film group formed on the silicon substrate 111 are collectively referred to as a chip. The assembly 110 is bonded to the beams 104 and 105 by the bonding portion 117. That is, the back surface of the silicon substrate is used as an adhesive surface with the beams 104 and 105. The assembly 110 smoothes the power high-frequency signal sent from the antenna 12 through the electrode pad 118 by the rectification / detection / modulation / demodulation circuit unit 115, and supplies it as a power source to each circuit in the chip as DC power of a constant voltage. To do. A predetermined current is supplied to the Wheatstone bridge circuit 112 (the resistor 112a and the dummy resistor 112b).

  FIG. 6 is a circuit diagram showing the Wheatstone bridge circuit 112, and FIG. 7 is a diagram showing the relationship between the shape of the resistor 112a and the dummy resistor 112b and the crystal orientation of the silicon substrate 111. The Wheatstone bridge circuit 112 includes, on the (001) surface of the single crystal silicon substrate 111, a set of resistors 112a provided on two opposite sides and a set of dummy resistors 112b provided on the other two opposite sides. Become. The resistor 112a is composed of a silicon crystal including a diffused resistor in which impurities are diffused, and the silicon crystal is a single crystal. That is, the resistor 112a is an element for measuring the amount of strain formed by locally diffusing a P-type impurity layer in the silicon substrate 111. The longitudinal direction (a straight line connecting both terminals of the resistor 112a) is formed so as to substantially coincide with the <−110> direction of the silicon substrate 111. Like the resistor 112a, the dummy resistor 112b is formed in a V shape by locally diffusing a P-type impurity layer in the silicon substrate 111. The lengths of the two linear portions forming the V-shape are equal, the longitudinal direction of one linear portion is the <100> direction, and the other longitudinal direction is a direction rotated by 90 ° with respect to the <100> direction. To. The dummy resistor 112b is formed in a V shape in this way, and while gaining a resistance value, as a whole, the dummy resistor 112b is rotated by 90 ° with respect to the <−110> direction that is the longitudinal direction of the resistor 112a <110>. It is formed so as to substantially coincide with the direction. In addition, the internal resistance values of the resistor 112a and the dummy resistor 112b are formed to be substantially the same value.

  When strain is applied to the beams 104 and 105 (stress is applied), the strain is transmitted from the beams 104 and 105 to the entire silicon substrate 111. That is, in the assembly 110, since the bonding portion 117 is disposed on the back surface of the silicon substrate 111 facing the element formation surface, the distortion of the beams 104 and 105 applies distortion to the entire silicon substrate 111 through the bonding portion 117. The strain sensor 11 measures this strain. Specifically, a voltage is applied to the Wheatstone bridge circuit 112 (the longitudinal direction of the resistor 112a and the dummy resistor 112b) in the silicon substrate 111 to supply a predetermined current. When strain is applied to the silicon substrate 111 (stress is applied), the internal resistance value of the Wheatstone bridge circuit 112 changes based on the piezoresistance effect. The strain sensor 11 detects the strain of the beams 104 and 105 by detecting the amount of voltage drop accompanying the change in the internal resistance value with respect to the predetermined current supplied. The detected voltage drop amount (corresponding to the strain amount of the beams 104 and 105) is converted into a digital signal through the strain sensor amplifier group 113 and the analog / digital converter 114, and from the antenna 12 to the antenna 21 (ECU) via the electrode pad 118. Sent.

  Since the resistance value of the impurity diffusion layer is strongly affected by temperature fluctuations, the temperature compensation circuit includes a resistor 112a as an active resistor that is sensitive to strain and a dummy resistor 112b that is not sensitive to strain. The Wheatstone bridge circuit 112 is configured. That is, in the case of a silicon single crystal, the piezoresistive effect has orthogonal anisotropy depending on the crystal orientation. Therefore, when strain is applied to the beams 104 and 105 (silicon substrate 111), the internal resistance value of only the resistor 112a constituting the Wheatstone bridge circuit 112 changes based on the piezoresistance effect, and the internal resistance value of the dummy resistor 112b is piezoresistive. The arrangement of the chip (the crystal orientation of the silicon and the arrangement of the resistors 112a and 112b) is adjusted with respect to the coordinate system (the distortion direction of the beams 104 and 105) serving as a distortion reference so as not to change based on the effect. Thereby, the difference between the outputs of the resistor 112a and the dummy resistor 112b with respect to the strain applied to the silicon substrate 111 is increased, and the sensitivity of the output of the bridge circuit 112 is increased. As described above, since the processing circuit of the strain sensor 11 is highly integrated in the same silicon substrate 111, the structure is compact. Note that the thickness of the silicon substrate 111 is desirably 100 μm or less. In this case, the strain value of the beams 104 and 105 and the strain value at the position of the strain sensor 11 (resistor 112a) can be substantially matched. That is, the measurement accuracy can be improved.

  The rotational angular velocity sensor 1 detects the rotational angular velocity ω of the body 100 (pinion shaft PS) based on the output signal of the strain sensor 11. Note that the circuit that detects the rotational angular velocity ω based on the output signal of the strain sensor 11 may be provided in the body 100, or may be provided in the receiving antenna unit 20 or the ECU, and is not particularly limited. Specifically, the output signal (distortion amount A1) of the first strain sensor 11a on one side of the rotation direction of one beam 104 and the output signal (strain of the third strain sensor 11c on one side of the rotation direction of the other beam 105). The sum (A1 + A2) with the amount A2) is defined as a strain amount A on one side in the rotational direction. Also, the output signal (strain amount B1) of the second strain sensor 11b on the other side in the rotation direction of one beam 104, and the output signal (strain amount B2) of the 4-strain sensor 11d on the other side in the rotation direction of the other beam 105 (B1 + B2) is defined as a strain amount B on the other side in the rotational direction. Then, based on the sum {(A1 + A2) + (B1 + B2)} of the strain amount A (= A1 + A2) on one side in the rotational direction and the strain amount B (= B1 + B2) on the other side in the rotational direction, the rotational angular velocity ω is detected. For example, {(A1 + A2) + (B1 + B2)} is multiplied by a predetermined coefficient to detect the rotational angular velocity ω.

[Operation of Example 1]
Next, the operation of the rotational angular velocity sensor 1 of the first embodiment will be described.
The rotational angular velocity sensor 1 detects the rotational angular velocity ω of the body 100 (pinion shaft PS) based on the output signal of the strain sensor 11. The output signal of the strain sensor 11 is generated when a centrifugal force acts on the beams 104 and 105 of the body 100 as the pinion shaft PS rotates. That is, since the beams 104 and 105 have a predetermined mass and are provided at positions separated from the axis O by a predetermined distance in the radial direction, a centrifugal force acts as the body 100 rotates. As shown in FIG. 3, when the centrifugal force α ′ acts on the beams 104 and 105, the radial lengths of the beams 104 and 105 change (decrease in the first embodiment). The strain sensor 11 detects and outputs the amount of change (decrease amount) in the radial length (based on a state where the centrifugal force α ′ does not act on the beams 104 and 105) as strain amounts A and B, respectively. Specifically, the first strain sensor 11a detects and outputs the amount of decrease in the radial length on one side in the rotational direction of the beam 104 as the strain amount A1. The second strain sensor 11b detects and outputs the amount of decrease in the radial length on the other side in the rotational direction of the beam 104 as the strain amount B1. The third strain sensor 11c detects and outputs the amount of decrease in the radial length on one side in the rotational direction of the beam 105 as the strain amount A2. The fourth strain sensor 11d detects and outputs the amount of decrease in the radial length on the other side in the rotational direction of the beam 105 as the strain amount B2. As described above, the rotational angular velocity sensor 1 changes the centrifugal force α ′ that changes according to the rotational angular velocity ω of the body 100 (pinion shaft PS) as the rotating body (acts on the beams 104 and 105 as the strain amount detection piece). Detect as A and B. As a result, it is possible to obtain information on the rotational angular velocity ω as the physical quantity itself without using the differential operation of the angle. Therefore, the detection accuracy of the rotational angular velocity ω can be improved.

  Specifically, the rotational angular velocity sensor 1 calculates the rotational angular velocity ω as a value corresponding to the output signal of the strain sensor 11 (for example, a value obtained by multiplying the output signal by a predetermined coefficient). FIG. 8 is a graph showing the relationship between the output signal (strain amounts A and B) of the strain sensor 11 and the rotational angular velocity ω. As shown in FIG. 8, the magnitude of the centrifugal force α ′ acting on the beams 104 and 105 increases as the rotational angular velocity ω increases. The quantities A and B) increase. Therefore, the rotational angular velocity ω can be calculated as a value corresponding to the strain amounts A and B.

  The beams 104 and 105 are provided such that the longitudinal direction (when viewed from the direction of the axis O) of the beams 104 and 105 substantially coincides with the radial direction of the rotating body (body 100). Therefore, since the centrifugal force α ′ acts in the longitudinal direction of the beams 104 and 105, the amount of change in the radial length of the beams 104 and 105 that changes due to the centrifugal force α ′ can be increased. For this reason, the detection accuracy of the distortion amounts A and B, that is, the detection accuracy of the rotational angular velocity ω can be improved.

  The strain sensor 11 detects the strain amounts A and B based on the change in the internal resistance value that changes based on the piezoresistance effect due to the force acting on the beams 104 and 105 (centrifugal force α ′). That is, silicon has a piezoresistive effect in which the resistance value changes when stress is applied. Thus, when a strain sensor using the piezoresistive effect is used, a strain sensor (for example, a resistance wire type strain gauge using a thin metal thin wire) that uses a change in resistance value due to a change in the cross-sectional area of the resistance. ), The change in the resistance value due to the strain is remarkably large, so that the strain amount can be detected with high detection accuracy. Therefore, the detection accuracy of the rotational angular velocity ω can be improved. The strain sensor 11 is supplied with a predetermined current, and detects the amount of distortion by detecting the amount of voltage drop accompanying the change in the internal resistance value with respect to this current. Therefore, the amount of distortion can be detected with a simple configuration.

  Further, the strain sensor 11 is constituted by a silicon crystal including a diffusion resistance in which impurities are diffused. Therefore, a highly accurate and reliable strain sensor can be obtained as compared with the case where a resistance wire strain gauge that easily causes high cycle fatigue is used. In other words, a semiconductor crystal with a high yield strength is used for applications involving high-cycle deformation such as measurement of rotational shaft distortion, or for applications that require high reliability such as automobile steering shafts. There is no fatigue even with cycle loads. Also, when a Wheatstone bridge circuit is configured using a plurality of resistors for temperature correction, there is no concern about resistance peeling or damage. Therefore, long-term reliability can be ensured. The silicon crystal is a single crystal. Therefore, it is a single crystal and has no grain boundaries compared to resistance wire strain gauges that are easily corroded by using metal thin films and semiconductor gauges that use polycrystalline silicon that can cause environmental corrosion at multiple crystal grain boundaries. Therefore, it is possible to obtain a strain sensor with high reliability and high detection accuracy that does not corrode even in a corrosive environment or in an environment with moisture. In addition, there are advantages such as good consistency with other electric circuits, high breaking strength, and low cost.

  The strain sensor 11 (especially one using the piezoresistive effect) has higher detection accuracy (sensitivity) than a normal sensor, and therefore, with respect to an external force (stress) input due to vehicle vibration or the like, a physical quantity other than that to be detected A device for removing or reducing disturbances (noise) is required. In contrast, the rotational angular velocity sensor of the first embodiment improves the detection accuracy of the rotational angular velocity ω by taking the following measures.

  The rotational angular velocity sensor 1 includes an output signal (strain amount A1) of the first strain sensor 11a that is a radial length change amount on one side of the beam 104 and a radial length on the other side of the same beam 104 in the rotational direction. The rotational angular velocity ω is detected based on the output signal (strain amount B1) of the second strain sensor 11b, which is the amount of change. Thus, based on the output signals of the strain sensor 11 provided on both sides of the beam 104, it is possible to reduce the influence accompanying the acceleration / deceleration of the body 100 (pinion shaft PS) and improve the detection accuracy of the rotational angular velocity ω. . That is, when the rotation of the body 100 accelerates or decelerates, the beam 104 tilts (falls down) to one side or the other side in the rotational direction (on the opposite side to the rotational direction during acceleration and to the rotational direction side during deceleration) as indicated by an arrow β in FIG. ), Bend. Therefore, distortion due to bending in the extending direction or contracting direction (direction β ′ in FIG. 3) is superimposed on the output of the strain sensor 11 together with distortion due to the centrifugal force α ′ (rotational angular velocity ω). The direction of distortion due to centrifugal force (direction of α ′ in FIG. 3) is the same on one side and the other side of the rotation direction of the same beam 104, while the direction of distortion due to the bending (β ′ in FIG. 3) is the same. Direction) is the opposite. In order to reduce the influence of the strain component caused by the bending by utilizing this anisotropy, the centrifugal force α is detected by detecting the rotational angular velocity ω based on the output signals of the strain sensor 11 provided on both sides of the beam 104. The distortion component due to ′ can be extracted with higher accuracy.

  Specifically, as indicated by a one-dot chain line in FIG. 8, the rotational angular velocity ω is calculated as a value corresponding to the sum (A1 + B1) of the output signals of both sensors 11a and 11b. By taking the sum of the output signals of the strain sensors 11 provided on both sides of the beam 104 in this way, the influence due to acceleration / deceleration of the body 100 (pinion shaft PS) is canceled and the detection accuracy of the rotational angular velocity ω is improved. Can do. That is, since the direction of distortion due to the bending (direction of β ′ in FIG. 3) is opposite between the one side and the other side in the rotation direction of the beam 104, the output of the strain sensor 11 provided on both sides of the beam 104 is reversed. By taking the sum of the signals, it is possible to cancel out the distortion component caused by the bending and extract only the distortion component caused by the centrifugal force α ′. Note that the rotational angular velocity ω may be calculated according to the sum (A2 + B2) of the output signals of the third and fourth strain sensors 11c and 11d. That is, based on the output signals of the pair of strain sensors 11 provided on at least one of the beams 104 and 105, the above-described effects can be obtained.

The rotational angular velocity sensor 1 includes an output signal of the first strain sensor 11a that is a radial length change amount on one side of one beam 104 and the same rotation direction side (one side of the rotation direction) of the other beam 105. The rotational angular velocity ω is detected based on the output signal of the third strain sensor 11c, which is the radial length change amount. As described above, by using the output signal of the strain sensor 11 of the beams 104 and 105 provided on the opposite side (opposite) with respect to the rotation center O of the body 100, a force (disturbance) other than the rotation direction is applied to the body 100. The influence of the addition can be reduced and the detection accuracy can be improved. That is, as a force other than the rotation direction, for example, when a radial force as indicated by an arrow γ in FIG. 3 acts on the body 100, for example, an outer radial force γ ′ acts on one beam 104, and the other On the contrary, a force γ ′ in the inner diameter direction acts on the beam 105. Therefore, the radial lengths of the beams 104 and 105 are decreased and increased, respectively. Therefore, the strain amount σ due to the disturbance γ ′ is superimposed on the output of the strain sensor 11 together with the strain amounts A and B due to the centrifugal force α ′. As shown in FIG. 9A, when one beam 104 is viewed, a distortion amount σ due to disturbance γ ′ is added to the output of the first strain sensor 11a provided on one side in the rotational direction (A1 ′ = A1 + σ). ), The strain amount σ is subtracted from the output of the second strain sensor 11b provided on the other side in the rotation direction (B1 ′ = B1-σ). As shown in FIG. 9B, regarding the other beam 105, the strain amount σ is subtracted from the output of the third strain sensor 11c provided on one side in the rotation direction (A2 ′ = A2−σ), and the rotation is performed. The strain amount σ is added to the output of the fourth strain sensor 11d provided on the other side in the direction (B2 ′ = B2 + σ). Looking at the first strain sensor 11a and the third strain sensor 11c provided on one side of the rotation direction of the beams 104 and 105, the magnitudes of the strain amounts A1 and A2 due to the rotation (due to the centrifugal force α ′) are substantially the same. Is the same. However, the beam 104 and the beam 105 have almost the same amount of strain σ due to the disturbance γ ′, but the directions are opposite.
Using this anisotropy, the rotational angular velocity ω is detected based on the output signal of the strain sensor 11 (provided on the same side in the rotational direction) of both beams 104, 105 provided on the opposite side of the body 100 in the radial direction. Thus, the influence of the distortion component σ due to the disturbance γ ′ can be reduced, and the distortion component due to the centrifugal force α ′ (rotational angular velocity ω) can be extracted more accurately.

  Specifically, the rotational angular velocity sensor 1 includes an output signal (strain amount A1 ′) of the first strain sensor 11a, which is a radial length change amount on one side of one beam 104, and the other beam 105. The sum (A1 ′ + A2 ′) of the output signal (strain amount A2 ′) of the third strain sensor 11c, which is the radial length change amount on one side in the rotational direction, is defined as the strain amount A on the one side in the rotational direction. Further, the output signal (strain amount B1 ′) of the second strain sensor 11b, which is the amount of change in the radial length on the other side in the rotational direction of one beam 104, and the radial length on the other side in the rotational direction of the other beam 105. The sum (B1 ′ + B2 ′) with the output signal (strain amount B2 ′) of the fourth strain sensor 11d, which is the change amount, is set as the strain amount B on the other side in the rotational direction. Then, based on the strain amount A (= A1 ′ + A2 ′) on one side in the rotational direction and the strain amount B (= B1 ′ + B2 ′) on the other side in the rotational direction (based on the sum of both), the rotational angular velocity ω is detected. . In this way, by taking the sum of the output signals of the strain sensors 11 of the beams 104 and 105 provided facing each other, an output signal in which the distortion component σ due to the disturbance γ ′ is canceled can be obtained, and the rotational angular velocity ω. Detection accuracy can be improved. That is, since the direction of the strain amount σ due to the disturbance γ ′ is opposite between the one beam 104 and the other beam 105, the sum of the output signals of the strain sensor 11 provided on the same rotation direction side of the beams 104 and 105 is obtained. Thus, the distortion component σ due to the disturbance γ ′ can be canceled, and only the distortion components A and B due to the centrifugal force α ′ (rotational angular velocity ω) can be extracted (for example, A1 ′ + A2 ′ = (A1 + σ) + (A2 −σ) = A1 + A2).

  Further, the dimensions of the beams 104 and 105 in the x-axis direction (the axial direction of the body 100) are larger than the dimensions of the beams 104 and 105 in the radial direction (the radial direction of the body 100). Therefore, even if a disturbance (force) is input in the axial direction of the body 100, the inclination (deflection) of the beams 104 and 105 in this axial direction is suppressed, so the amount of change in the radial length of the beams 104 and 105 due to centrifugal force The detection accuracy, that is, the detection accuracy of the rotational angular velocity ω can be improved. Specifically, since the beams 104 and 105 are provided over the entire range of the body 100 in the axial direction, the above-described effects can be improved by maximizing the dimension in the x-axis direction (the axial direction of the body 100). The beams 104 and 105 can be formed more easily than when the body 100 is provided in a partial range in the axial direction. Furthermore, since the strain sensor 11 is arranged in the center of the beams 104 and 105 in the axial direction of the body 100, even if a disturbance (force) is input in the axial direction of the body 100, the influence is more effectively suppressed. can do.

  In addition, since the body 100 is fastened and fixed to the pinion shaft PS by the screws 14 as fixing means, the play of the body 100 with respect to the pinion shaft PS can be suppressed. For this reason, it is possible to suppress the influence of disturbance due to rattling and to improve the detection accuracy of the amount of change in the radial length of the beams 104 and 105 due to the centrifugal force, that is, the detection accuracy of the rotational angular velocity ω.

  In the first embodiment, the beams 104 and 105 are provided as a structure for detecting distortion in which distortion occurs due to centrifugal force with rotation. However, the beam is not particularly provided, and a pinion shaft PS or other steering shaft SS (rotating body) is conventionally provided. The strain sensor 11 may be attached to this structure using a structure existing in the structure. In other words, the body 100 may be omitted. Since the body 100 is provided in the first embodiment, the degree of freedom of the attachment position of the rotational angular velocity sensor 1 can be improved. In addition, by providing the body 100 with the beams 104 and 105 as a strain detection structure, it is possible to improve the detection accuracy of the strain generated with respect to the input in a predetermined direction. Specifically, the beams 104 and 105 as strain detection structures are provided in a shape in which stress is not easily transmitted from the body 100 in which the beams 104 and 105 are provided. That is, for example, when the body 100 is fixed to the rotating shaft (pinion shaft PS) (clamped and fixed by the screw 14), the body 100 is provided with the recesses 102 and 103 so that stress generated in the body 100 is not transmitted to the beams 104 and 105 as much as possible. The beams 104 and 105 are formed so as to protrude from the bottoms of the recesses 102 and 103. Further, the base portions of the beams 104 and 105 (the bottom portions of the recesses 102 and 103) are provided not on the inner periphery side of the body 100 but on the outer periphery side so that stress due to bending of the rotating shaft (pinion shaft PS) is not transmitted to the beams 104 and 105 as much as possible. Therefore, the strain sensor 11 attached to the beams 104 and 105 is prevented from detecting the stress (disturbance) transmitted from the body 100, and it is facilitated to detect only the stress acting on the beams 104 and 105 by the rotation. The detection accuracy of the angular velocity ω can be improved. The shapes of the beams 104 and 105 are not limited to those of the first embodiment. For example, in the first embodiment, the circumferential widths (plate thicknesses) of the beams 104 and 105 are provided substantially uniformly, but may be provided so that the plate thickness decreases, for example, toward the axis O.

[Effect of Example 1]
Hereinafter, effects exhibited by the rotational angular velocity sensor 1 of the first embodiment will be listed.
(1) The rotating body (body 100) is provided at a position spaced apart from the rotation center (axis O) in the radial direction by a predetermined distance, has a predetermined mass so that centrifugal force acts upon rotation of the rotating body, The strain amount detection piece (beam 104) formed so that the length in the radial direction is reduced by the action of force, and provided on one side of the rotation direction of the strain amount detection piece when the rotation direction of the rotating body is the rotation direction. The first strain sensor 11a for detecting the strain amount A1 on the one side of the strain amount detection piece, and the other strain direction detection piece B1 provided on the other side in the rotational direction of the strain amount detection piece. Of the first strain sensor 11a and the second strain sensor 11b, which are the amount of change in the length in the radial direction of the strain amount detection piece that is reduced by the centrifugal force acting on the strain amount detection piece. Rotational angular velocity of rotating body based on output signal To detect the ω.
Therefore, since rotational angular velocity information that does not depend on the differential calculation of the angle can be obtained, detection accuracy can be improved.

(2) The strain amount detection piece (beam 104) is provided so that the longitudinal direction of the strain amount detection piece substantially coincides with the radial direction of the rotating body (body 100).
Therefore, since the amount of change in the radial length of the strain amount detection piece that changes due to the centrifugal force can be increased, the detection accuracy can be improved.

(3) Provided on the opposite side of the strain detection piece (beam 104) with respect to the rotation center (axis O) of the rotating body (body 100), and having a predetermined mass so that centrifugal force acts as the rotating body rotates. A counter piece (beam 105) formed so that the radial length is reduced by the action of centrifugal force, and provided on one side of the counter piece in the rotational direction, and the strain amount A2 on the one side of the counter piece A third strain sensor 11c to detect, and a fourth strain sensor 11d provided on the other side of the counterpiece in the rotational direction and detecting the strain amount B2 on the other side of the counterpiece, and centrifugal force acts on the counterpiece The sum of the output signal A2 ′ of the third strain sensor 11c and the output signal A1 ′ of the first strain sensor 11a, which is the amount of change in the length in the radial direction of the counter piece that decreases as a result, is set as the strain amount A on one side in the rotational direction, Cow The sum of the output signal B2 ′ of the fourth strain sensor 11d and the output signal B1 ′ of the second strain sensor 11b, which is the amount of change in the length of the counterpiece in the radial direction, which is reduced by the centrifugal force acting on the intermediate piece, is the other side in the rotational direction. The rotational angular velocity ω of the rotating body is detected based on the strain amount A on one side in the rotational direction and the strain amount B on the other side in the rotational direction.
Therefore, even if a force other than the rotation direction acts on the rotating body, an output signal that cancels this force can be obtained, so that the detection accuracy can be improved.

(4) The first strain sensor 11a and the second strain sensor 11b are the one of the strain amount detection pieces based on the change of the internal resistance value that changes based on the piezoresistance effect by the force acting on the strain amount detection piece (beam 104). The distortion amount A on the side and the distortion amount B on the other side are detected.
Therefore, detection accuracy can be improved by using a strain sensor using a piezoresistance effect.

(5) The first strain sensor 11a and the second strain sensor 11b are supplied with a predetermined current, and detect strain amounts A1 and B1 by detecting a voltage drop amount accompanying a change in internal resistance value with respect to the current.
Therefore, the configuration can be simplified.

(6) The first strain sensor 11a and the second strain sensor 11b are made of silicon crystals including a diffused resistor in which impurities are diffused.
Therefore, it is possible to improve detection accuracy while improving reliability.

(7) The silicon crystal is a single crystal.
Therefore, it is possible to improve detection accuracy while improving reliability.

[Example 2]
In the second embodiment, a rotational angular acceleration sensor will be described. In the following, it is assumed that the rotational angular acceleration dω includes both acceleration and deceleration.
The power steering device EPS to which the rotational angular acceleration sensor of the second embodiment is applied, instead of the rotational angular velocity sensor 1, is a rotational angle as a steering angular acceleration detection means that detects the rotational angular acceleration dω of the pinion shaft PS as the steering angular acceleration. An acceleration sensor 1 is included. When the steering wheel SW is steered by the driver, the rotational angular acceleration (steering angular acceleration) dω transmitted to the pinion shaft PS via the steering shaft SS is detected by the rotational angular acceleration sensor 1 and output to the ECU. . The ECU corrects the steering assist amount based on the input rotational angular acceleration dω, and performs control for improving steering operability and steering feeling. For example, the steering feeling is improved by performing inertia compensation, viscosity compensation, and the like for correcting the steering assist amount using a compensation value created based on the detected value of the rotational angular acceleration dω. The content of this compensation control is a well-known technique and will not be described. Other configurations of the EPS are the same as those in the first embodiment. The configuration of the rotation angular acceleration sensor 1 is the same as that of the rotation angular velocity sensor 1 of the first embodiment. That is, the rotational angular acceleration sensor 1 is configured as a sensor unit 10 in which a sensor body (strain sensor 11) and a transmission-side antenna 12 are integrally assembled with a body 100. Send and receive power. The configurations of the strain amount detection piece and counter piece (beam 104 and beam 105) and the first to first strain sensors 11a to 11d are the same as those of the rotational angular velocity sensor 1. The beams 104 and 105 have a predetermined mass and shape so that the body 100 is bent in the rotation direction as the body 100 rotates.

  The rotational angular acceleration sensor 1 detects the rotational angular acceleration dω of the body 100 (pinion shaft PS) based on the output signal of the strain sensor 11. The circuit for detecting the rotational angular acceleration dω based on the output signal of the strain sensor 11 may be provided in the body 100, may be provided in the receiving antenna unit 20 or the ECU, and is not particularly limited. Specifically, the output signal (distortion amount A1) of the first strain sensor 11a on one side of the rotation direction of one beam 104 and the output signal (strain of the third strain sensor 11c on one side of the rotation direction of the other beam 105). The sum (A1 + A2) with the amount A2) is defined as a strain amount A on one side in the rotational direction. Also, the output signal (strain amount B1) of the second strain sensor 11b on the other side in the rotation direction of one beam 104, and the output signal (strain amount B2) of the 4-strain sensor 11d on the other side in the rotation direction of the other beam 105 (B1 + B2) is defined as a strain amount B on the other side in the rotational direction. Then, the rotational angular acceleration dω is detected based on the difference {(A1 + A2) − (B1 + B2)} between the strain amount A (= A1 + A2) on one side in the rotational direction and the strain amount B (= B1 + B2) on the other side in the rotational direction. For example, {(A1 + A2)-(B1 + B2)} is multiplied by a predetermined coefficient to detect the rotational angular acceleration dω.

(Operation of Example 2)
The output signal of the strain sensor 11 is generated when the beams 104 and 105 of the body 100 are bent in the rotational direction (arrow β in FIG. 3) with the rotation of the pinion shaft PS. That is, when a rotational force is applied to the beams 104 and 105, as shown by an arrow β ′ in FIG. 3, the beam 104 and 105 is bent in the extension direction on one side in the rotation direction, and is bent in the contraction direction on the other side in the rotation direction. Will occur. The strain sensor 11 detects and outputs the amount of bending in the extension direction and the amount of bending in the contraction direction as a strain amount (based on a state where the beams 104 and 105 are not bent). The sign of the amount of strain corresponding to the deflection is opposite between the extension direction and the contraction direction of the deflection. Specifically, the first strain sensor 1 detects and outputs a deflection amount (for example, positive) on one side of the beam 104 in the rotational direction (for example, in the extension direction) as a (for example, positive) strain amount A1, while the second strain sensor 11b. Detects and outputs the deflection amount (in the contraction direction) on the other side of the beam 104 in the rotational direction as a (for example, negative) strain amount B1. Similarly, the third strain sensor 11c detects and outputs the amount of deflection on one side of the beam 105 in the rotational direction as a positive strain amount A2 (for example, positive), while the fourth strain sensor 11d The side deflection amount is detected and output as a (for example, negative) strain amount B2. In this manner, the deflection (of the beams 104 and 105 as the strain amount detection piece) that changes in accordance with the rotational angular acceleration dω of the body 100 as the rotating body is detected as the strain amount. Thereby, the information of the rotational angular acceleration dω as the physical quantity itself can be obtained without using the second-order differential of the angle. Therefore, the detection accuracy of the rotational angular acceleration dω can be improved.

  Specifically, the rotational angular acceleration sensor 1 calculates the rotational angular acceleration dω as a value corresponding to the output signal of the strain sensor 11 (for example, a value obtained by multiplying the output signal by a predetermined coefficient). That is, as shown in FIG. 10 showing the relationship between the output signal (strain amounts A and B) of the strain sensor 11 and the rotational angular acceleration dω, the beams 104 and 105 are increased as the rotational angular acceleration dω increases. The amount of bending generated in the beam increases, and the strain amounts A and B of the beams 104 and 105 increase. Therefore, the rotational angular acceleration dω can be calculated as a value corresponding to the strain amounts A and B. The operational effects obtained by using the strain sensors 11a to 11d utilizing the piezoresistance effect of single crystal silicon are the same as those in the first embodiment.

  Further, the rotational angular acceleration sensor 1 of the second embodiment improves the detection accuracy of the rotational angular acceleration dω by taking the following countermeasures against external force (stress) input due to vehicle vibration or the like. .

  The rotation angular acceleration sensor 1 includes an output signal (strain amount A1) of the first strain sensor 11a that is a deflection amount on one side in the rotation direction of the beam 104, and a second strain that is a deflection amount on the other side in the rotation direction of the same beam 104. Based on the output signal (distortion amount B1) of the sensor 11b, the rotational angular acceleration dω is detected. Thus, based on the output signals of the strain sensor 11 provided on both sides of the beam 104, the influence of the centrifugal force α ′ accompanying the rotation of the body 100 (pinion shaft PS) is reduced, and the detection accuracy of the rotational angular acceleration dω is improved. Can be improved. That is, when the body 100 rotates, the radial lengths of the beams 104 and 105 change (decrease) due to the centrifugal force α ′, so that the distortion sensor output includes the distortion due to the bending β ′ (rotational angular acceleration dω) as well as the above. Distortion due to the centrifugal force α ′ is superimposed. The direction of distortion due to the centrifugal force α ′ is the same on one side and the other side in the rotational direction of the beam 104, while the direction of distortion due to the bending β ′ is opposite. In order to reduce the influence of the strain component due to the centrifugal force α ′ by utilizing this anisotropy, the rotational angular acceleration dω is detected based on the output signals of the strain sensor 11 provided on both sides of the beam 104, thereby bending. It is possible to extract a distortion component due to the removal more accurately.

  Specifically, as shown in FIG. 10, as a value corresponding to the difference (A1-B1) between the output signals of both sensors 11a, 11b (for example, as a value obtained by multiplying (A1-B1) by a predetermined coefficient), The rotational angular acceleration dω is calculated. By taking the difference between the output signals of the strain sensors 11 provided on both sides of the beam 104 in this way, the influence of the centrifugal force α ′ accompanying the rotation of the body 100 (pinion shaft PS) is canceled and the detection accuracy is improved. Can do. That is, since the direction of distortion due to the centrifugal force α ′ is the same on one side and the other side in the rotational direction of the beam 104, the difference in the output signals of the strain sensors 11 provided on both sides of the beam 104 (A1-B2). By taking the above, it is possible to cancel the distortion component due to the centrifugal force α ′ and to extract only the distortion component due to the bending β ′ due to acceleration / deceleration. The rotational angular acceleration dω may be calculated according to the difference (A2−B2) between the output signals of the third and fourth strain sensors 11c and 11d. That is, based on a set of strain sensors 11 provided on at least one of the beams 104 and 105, the above-described effects can be obtained.

  In addition, the rotation angular acceleration sensor 1 includes the output signal of the first strain sensor 11a that is the amount of bending of one beam 104 on one side in the rotation direction, and the bending of the other beam 105 on the same rotation direction side (one direction of rotation). The rotational angular acceleration dω is detected based on the output signal of the third strain sensor 11c, which is a quantity. As described above, by using the output signals of the strain sensors 11 of the beams 104 and 105 provided on the opposite side with respect to the rotation center O of the body 100, the influence due to the force (disturbance) other than the rotation direction being applied to the body 100. And the detection accuracy can be improved. That is, as described in the first embodiment, when a radial force (disturbance) is applied to the body 100 as a force other than the rotation direction, for example, as indicated by an arrow γ in FIG. The magnitude of the distortion amount σ due to the disturbance is almost the same, but the direction is opposite. Using this anisotropy, the rotational angular acceleration dω is detected based on the output signal of the strain sensor 11 (provided on the same side in the rotational direction) of both beams 104 and 105 provided on the opposite side of the body 100 in the radial direction. Thus, the influence of the distortion component due to the disturbance can be reduced, and the distortion component due to bending (rotational angular acceleration dω) can be extracted more accurately.

  Specifically, the rotational angular acceleration sensor 1 is configured such that the output signal (strain amount A1 ′) of the first strain sensor 11a, which is the amount of deflection on one side in the rotational direction of one beam 104, and one of the rotational directions of the other beam 105. The sum (A1 ′ + A2 ′) of the output signal (strain amount A2 ′) of the third strain sensor 11c, which is the deflection amount on the side, is defined as the strain amount A on one side in the rotational direction. Further, the output signal (strain amount B1 ′) of the second strain sensor 11b, which is the amount of deflection on the other side in the rotational direction of one beam 104, and the fourth strain sensor, which is the amount of deflection on the other side in the rotational direction of the other beam 105. The sum (B1 ′ + B2 ′) of the 11d output signal (distortion amount B2 ′) is defined as the distortion amount A on the other side in the rotational direction. Then, based on the strain amount A (= A1 ′ + A2 ′) on the one side in the rotational direction and the strain amount B (= B1 ′ + B2 ′) on the other side in the rotational direction (based on the difference between them), the rotational angular acceleration dω is detected. To do. In this way, by taking the sum of the output signals of the strain sensors 11 of the beams 104 and 105 provided facing each other, an output signal in which the distortion component σ due to the disturbance γ ′ is canceled can be obtained, and the rotational angular acceleration is obtained. The detection accuracy of dω can be improved. That is, since the direction of the strain amount σ due to the disturbance γ ′ is opposite between the one beam 104 and the other beam 105, the sum of the output signals of the strain sensor 11 provided on the same rotation direction side of the beams 104 and 105 is obtained. Thus, the distortion component σ due to the disturbance γ ′ can be canceled, and only the distortion components A and B due to the bending β ′ (rotational angular acceleration dω) can be extracted (for example, A1 ′ + A2 ′ = (A1 + σ) + (A2 −σ) = A1 + A2).

  Here, the beams 104 and 105 are provided so that the longitudinal direction (when viewed from the direction of the axis O) of the beams 104 and 105 substantially coincides with the radial direction of the rotating body (body 100). Therefore, the amount of bending of the beams 104 and 105 caused by the rotational force can be increased. For this reason, the detection accuracy of the distortion amounts A and B, that is, the detection accuracy of the rotational angular acceleration dω can be improved. Since other operations are the same as those of the first embodiment, description thereof is omitted.

(Effect of Example 2)
Hereinafter, effects exhibited by the rotational angular acceleration sensor 1 of the second embodiment will be listed.
(8) It is provided at a position spaced apart from the rotation center (axis O) of the rotating body (body 100) by a predetermined distance in the radial direction, and a predetermined amount is generated so that the rotating body bends in the rotating direction as the rotating body rotates. A strain amount detection piece (beam 104) having a mass and a shape, and provided on one side of the strain amount detection piece when the rotation direction of the rotating body is the rotation direction, the strain on the one side of the strain amount detection piece A first strain sensor 11a that detects the amount A, and a second strain sensor 11b that is provided on the other side in the rotational direction of the strain amount detection piece and detects the strain amount B on the other side of the strain amount detection piece, When each of the first strain sensor 11a and the second strain sensor 11b detects the deflection in the extension direction and the deflection in the contraction direction by the deflection of the strain amount detection piece, the output signal A1 of the first strain sensor 11a and the second strain sensor Rotating body based on the difference of the output signal B1 of 11b For detecting the rotational angular acceleration dω.
Therefore, since rotational angular acceleration information that does not depend on the differential calculation of the angle can be obtained, the detection accuracy can be improved.

(9) The strain amount detection piece (beam 104) is provided so that the longitudinal direction of the strain amount detection piece substantially coincides with the radial direction of the rotating body (body 100).
Therefore, since the amount of distortion of the strain amount detection piece caused by the rotational force can be increased, the detection accuracy can be improved.

(10) Provided on the opposite side of the strain detection piece (beam 104) with respect to the rotation center (axis O) of the rotating body (body 100), and the rotating body is bent in the rotating direction as the rotating body rotates. A counter piece (beam 105) having a predetermined mass and shape, a third strain sensor 11c that is provided on one side of the counter piece in the rotation direction and detects a strain amount A2 on the one side of the counter piece, and a counter A fourth strain sensor 11d that is provided on the other side of the piece rotation direction and detects the amount of strain B2 on the other side of the counterpiece. The output signal A1 ′ of the first strain sensor 11a and the third strain sensor 11c The sum of the output signals A2 ′ is the distortion amount A on one side in the rotational direction, and the sum of the output signals B1 ′ of the second strain sensor 11b and the output signal B2 ′ of the fourth strain sensor 11d is the strain amount B on the other side of the rotational direction. , Amount of distortion A on one side of the rotation direction Based on the difference of the distortion amount B in the rotational direction the other side, to detect the rotational angular acceleration dω of the rotating body.
Therefore, even if a force other than the rotation direction acts on the rotating body, an output signal that cancels this force can be obtained, so that the detection accuracy can be improved.

(11) The first strain sensor 11a and the second strain sensor 11b are the one of the strain amount detection pieces based on the change of the internal resistance value that changes based on the piezoresistance effect by the force acting on the strain amount detection piece (beam 104). The distortion amount A on the side and the distortion amount B on the other side are detected.
Therefore, detection accuracy can be improved by using a strain sensor using a piezoresistance effect.

(12) The first strain sensor 11a and the second strain sensor 11b are supplied with a predetermined current, and detect strain amounts A1 and B1 by detecting a voltage drop amount accompanying a change in internal resistance value with respect to the current.
Therefore, the configuration can be simplified.

(13) The first strain sensor 11a and the second strain sensor 11b are made of silicon crystals including a diffusion resistor in which impurities are diffused.
Therefore, it is possible to improve detection accuracy while improving reliability.

(14) The silicon crystal is a single crystal.
Therefore, it is possible to improve detection accuracy while improving reliability.

[Other embodiments]
As mentioned above, although the form for implement | achieving this invention has been demonstrated based on Example 1, the concrete structure of this invention is not limited to an Example, The design of the range which does not deviate from the summary of invention Any changes and the like are included in the present invention.
For example, in the first and second embodiments, the rotational angular velocity sensor 1 and the rotational angular acceleration sensor 1 are independently applied to the power steering device EPS, but both the rotational angular velocity sensor 1 and the rotational angular acceleration sensor 1 are simultaneously used. It is good also as applying to EPS. In this case, since the rotational angular velocity sensor 1 and the rotational angular acceleration sensor 1 are provided as an integrated sensor having the same component parts, the number of parts can be reduced.
In the first and second embodiments, the rotational angular velocity sensor 1 and the rotational angular acceleration sensor 1 are applied to the rotational shaft (steering shaft SS) of the EPS, but may be applied to the rotational shaft of any other device. it can. Moreover, it is applicable not only to a rotating shaft but to an arbitrary rotating body.
In the first and second embodiments, the beams 104 and 105 are provided so as to protrude toward the inner peripheral side of the body 100. However, the beams 104 and 105 are provided so as to protrude toward the outer peripheral side of the body 100. It is good also as forming so that a radial direction dimension may increase. In this case, the concept is the same as in the first and second embodiments, except that the sign of the distortion amount with respect to centrifugal force and radial disturbance is changed. Alternatively, one of the beams 104 and 105 may be provided so as to protrude toward the inner peripheral side of the body 100, and the other may be provided so as to protrude toward the outer peripheral side.
The receiving-side antenna unit 20 is not limited to the position facing the sensor unit 10 in the axial direction, and may be installed so as to surround the outer periphery of the sensor unit 10, for example. In the first embodiment, the antenna of the sensor unit 10 is formed with a large antenna outside in order to obtain electric power (output), but may be built in the chip. In this case, an electrode pad for external connection becomes unnecessary, the electrode is not exposed to the chip surface, and even when used in a poor environment, the electrode pad is not corroded and the reliability can be improved. In the first embodiment, power is supplied to the strain sensor 11 from the outside of the sensor unit 10, but a power source (storage battery) may be provided in the chip. Energy supply and communication with the ECU include electromagnetic induction that forms an induction electromagnetic field in the antenna, microwave reception and demodulation, and energy supply and communication using light. But you can. Moreover, not only a wireless format but a wired format using a slip ring or a fixed harness may be used.
The crystal orientation of silicon and the arrangement of the resistors 712a and 712b are not limited to those of the embodiment, and can be arbitrarily adjusted. For example, any of the following combinations may be used.
1) The resistor 712a is an N-type impurity diffusion layer and the <100> direction is long, the dummy resistor 712b is a P-type impurity diffusion layer and the <100> direction is long, and two resistors 712a and two dummy resistors 712b are arranged in parallel. 2) The resistor 712a is an N-type impurity diffusion layer with the <100> direction as the length, the dummy resistor 712b is formed of an N-type impurity diffusion layer, and the dummy resistor 712b is a V-shaped straight line that forms a V-shape. 3) The resistor 712a is formed of a P-type impurity diffusion layer, the dummy resistor 712b is formed of an N-type impurity diffusion layer, and both the resistor 712a and the dummy resistor 712b are <110>. It is formed so that the direction is long, and two resistors 712a and two dummy resistors 712b are arranged in parallel.

100 body (rotating body)
104 Beam (Strain detection piece)
105 Beam (Counterpiece)
11a First strain sensor 11b Second strain sensor 11c Third strain sensor 11d Fourth strain sensor

Claims (10)

The rotating body is provided at a position spaced a predetermined distance in the radial direction from the rotation center of the rotating body, has a predetermined mass so that centrifugal force acts as the rotating body rotates, and the radial length is increased by the action of the centrifugal force. A strain detection piece formed to increase or decrease;
A first strain sensor that is provided on one side in the rotation direction of the strain amount detection piece and detects the strain amount on the one side of the strain amount detection piece, when the rotation direction of the rotating body is a rotation direction;
A second strain sensor that is provided on the other side in the rotational direction of the strain amount detection piece and detects the strain amount on the other side of the strain amount detection piece,
The rotation is based on the output signals of the first strain sensor and the second strain sensor, which are the amount of change in length in the radial direction of the strain amount detection piece that increases or decreases when the centrifugal force acts on the strain amount detection piece. A rotational angular velocity sensor characterized by detecting a rotational angular velocity of a body. The rotational angular velocity sensor according to claim 1,
The rotational angular velocity sensor, wherein the strain amount detection piece is provided so that a longitudinal direction of the strain amount detection piece substantially coincides with a radial direction of the rotating body. The rotational angular velocity sensor according to claim 1,
It is provided on the opposite side of the strain detection piece with respect to the rotation center of the rotating body, has a predetermined mass so that centrifugal force acts as the rotating body rotates, and has a radial length by the action of the centrifugal force. A counterpiece formed to increase or decrease in length;
A third strain sensor that is provided on one side of the counterpiece in the rotational direction and detects a strain amount on the one side of the counterpiece;
A fourth strain sensor provided on the other side of the counter piece in the rotational direction and detecting a strain amount on the other side of the counter piece,
The sum of the output signal of the third strain sensor and the output signal of the first strain sensor, which is the amount of change in the radial length of the counter piece that increases or decreases when the centrifugal force acts on the counter piece, in the rotation direction The amount of distortion on one side
The sum of the output signal of the fourth strain sensor and the output signal of the second strain sensor, which is the amount of change in length in the radial direction of the counter piece that increases or decreases when the centrifugal force acts on the counter piece The amount of distortion on the other side,
A rotational angular velocity sensor that detects a rotational angular velocity of the rotating body based on a strain amount on one side in the rotational direction and a strain amount on the other side in the rotational direction. A strain amount detection piece which is provided at a position spaced apart from the rotation center of the rotating body by a predetermined distance in the radial direction and has a predetermined mass and shape so as to bend in the rotating direction of the rotating body with the rotation of the rotating body. When,
A first strain sensor that is provided on one side in the rotation direction of the strain amount detection piece and detects the strain amount on the one side of the strain amount detection piece, when the rotation direction of the rotating body is a rotation direction;
A second strain sensor that is provided on the other side in the rotational direction of the strain amount detection piece and detects the strain amount on the other side of the strain amount detection piece,
When each of the first strain sensor and the second strain sensor detects a deflection in the extension direction and a deflection in the contraction direction by the deflection of the strain amount detection piece, the output signal of the first strain sensor and the second strain are detected. A rotational angular acceleration sensor for detecting a rotational angular acceleration of the rotating body based on a difference in sensor output signals. The rotational angular acceleration sensor according to claim 4,
The rotation amount acceleration sensor, wherein the strain amount detection piece is provided so that a longitudinal direction of the strain amount detection piece substantially coincides with a radial direction of the rotating body. The rotational angular acceleration sensor according to claim 4,
A counter provided on the opposite side of the strain amount detection piece with respect to the rotation center of the rotating body and having a predetermined mass and shape so that the rotating body is bent in the rotating direction as the rotating body rotates. With pieces,
A third strain sensor that is provided on one side of the counterpiece in the rotational direction and detects a strain amount on the one side of the counterpiece;
A fourth strain sensor provided on the other side of the counter piece in the rotational direction and detecting a strain amount on the other side of the counter piece,
The sum of the output signal of the first strain sensor and the output signal of the third strain sensor is the strain amount on one side in the rotational direction,
The sum of the output signal of the second strain sensor and the output signal of the fourth strain sensor is the amount of strain on the other side in the rotational direction,
A rotational angular acceleration sensor that detects rotational angular acceleration of the rotating body based on a difference between a strain amount on one side of the rotational direction and a strain amount on the other side of the rotational direction. The rotational angular velocity sensor according to claim 1 or the rotational angular acceleration sensor according to claim 4,
The first strain sensor and the second strain sensor include a strain amount on the one side of the strain amount detection piece based on a change in an internal resistance value that changes based on a piezoresistance effect due to a force acting on the strain amount detection piece, and A rotational angular velocity sensor or a rotational angular acceleration sensor that detects a strain amount on the other side. The rotational speed sensor or rotational angular acceleration sensor according to claim 7,
The first strain sensor and the second strain sensor are supplied with a predetermined current, and detect the amount of distortion by detecting a voltage drop amount associated with a change in the internal resistance value with respect to the current. Rotational angular velocity sensor or rotational angular acceleration sensor. The rotational angular velocity sensor or the rotational angular acceleration sensor according to claim 8,
The first strain sensor and the second strain sensor are made of a silicon crystal including a diffusion resistor in which impurities are diffused, and a rotational angular velocity sensor or a rotational angular acceleration sensor. The rotational angular velocity sensor or the rotational angular acceleration sensor according to claim 9,
The rotational angular velocity sensor or the rotational angular acceleration sensor, wherein the silicon crystal is a single crystal.

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