JP4333381B2 - Torque sensor and electric power steering device - Google Patents

Description

  The present invention relates to a torque sensor that detects torque by a load sensor, and an electric power steering apparatus including the torque sensor.

  2. Description of the Related Art Conventionally, an electric power steering device that assists steering torque by driving a power assist motor based on steering torque applied to the steering by a driver's steering operation is known. In such an electric power steering apparatus, a torque sensor is provided on a steering shaft that is rotated by a steering operation, and a steering torque is detected. The detected torque is input as an electrical signal to a control computer (hereinafter also referred to as ECU), which drives the power assist motor based on the detected torque to assist the rotation of the steering shaft. .

  Many of the torque sensors described above are configured to detect, for example, a twist angle of a torsion bar and convert it into torque. Further, for example, as in Patent Document 1 and Patent Document 2, there are some that use a piezoelectric element or a load sensor element that detects a load instead of a twist angle of a torsion bar and converts it into a torque. In such a torque sensor, in order to detect the torque with high accuracy, the friction and gap generated in the movable part are eliminated so that there is no hysteresis generated between the actual torque and the detected torque, and no dead band where the torque is not detected. It is desired to be configured. In addition, with the recent increase in the number of vehicle components, there has been a demand for miniaturization as well as higher accuracy in torque detection.

Real Application 61-107683 JP-A-9-240296

  However, in the conventional torque sensor, it has been difficult to eliminate the presence of such friction, hysteresis, and dead zone. For example, in a torsion bar type torque sensor, it is necessary to prevent misalignment of the central axis between the steering shaft and the wheel turning shaft (pinion shaft, etc.), so bearings (bearings, etc.) are always required. There is friction between the shaft and the shaft. There is also a problem that the number of components increases due to the addition of bearings. Moreover, although the torque sensor described in Patent Document 1 has a simple structure, when actually configuring the torque sensor, the load sensor is assembled by insertion assembly. In this case, after assembly, A gap is created between the load sensor and the load receiving surface. This gap is intentionally provided in order to prevent an excessive stress from being generated at the time of insertion. However, due to the presence of this gap, a dead band is generated in the vicinity of the torque neutral point at the time of torque detection. Moreover, the torque sensor described in Patent Document 2 includes a disc spring between the load sensor and the load receiving surface, and the dead zone can be eliminated by applying a preload to the disc spring. However, as shown in FIG. 1 b of the publication, the projecting shaft portion 33 is rotatably fitted in the center hole 23, and sliding friction occurs between the projecting shaft portion 33 and the center hole 23. Hysteresis due to the friction occurs. Further, since a bearing or the like for reducing these frictions is required, the cost is increased.

  In addition, it is difficult to reduce the size of these torque sensors. For example, in the case of a torsion bar type torque sensor, bearings are required at both ends of the torsion bar, and the long sensor is configured to be long in the long axis direction.

  The present invention has been made in view of the above problems, and a torque sensor that eliminates the dead band and suppresses the occurrence of hysteresis to ensure high detection accuracy and enables miniaturization thereof, and the torque sensor. Is an electric power steering device using

Means for Solving the Problems and Effects of the Invention

  In order to solve the above-described problems, the torque sensors of the present invention are coaxially provided around a predetermined axis, are connected to each other, and face each other through a gap of a predetermined interval in the circumferential direction of the axis. Two rotating members composed of a first rotating member and a second rotating member having opposing surfaces, and a ceramic load sensor sandwiched between the two rotating members in the gap, and between the two rotating members When the torque is generated, the two rotating members are slightly twisted with respect to each other in the circumferential direction, so that the opposing surfaces approach each other, and the load sensor is compressed based on the approach of the opposing surfaces. The load is detected by the following.

  The torque sensor includes two rotating members provided coaxially around a predetermined rotation axis, and both are connected to form an integral structure. At this time, the two rotating members are connected so as to create a gap having a predetermined width between the two members in the circumferential direction of the rotating shaft, that is, in the direction in which the rotating member can rotate. A load sensor is provided in the gap formed by this connection, and is tightly held between both rotating members without a gap. Since it can arrange | position without producing a clearance gap between a load sensor and a rotation member, the torque sensor of this invention can detect a torque accurately, without producing a dead zone.

  Further, when torque is applied between the two rotating members, the torque is transmitted via the connecting portion and the load sensor, but most of the torque is applied to the load due to slight deflection of the connecting portion. At this time, the load sensor is clamped between the two rotating members and receives a compressive load based on the clamping pressure. The load sensor detects this compressive load, and the torque applied to the rotating member can be detected based on the detected value. At this time, friction such as sliding friction does not occur. Therefore, the torque applied to the rotating member is transmitted to the load sensor as a load without being lost due to friction or the like, so that the torque can be detected with high accuracy.

  Moreover, the conventional torsion bar type torque sensor includes a torsion bar 7 having a predetermined length as shown in FIG. 3, for example, and detects torque based on the difference in relative torsional displacement between one end and the other end. Therefore, it is necessary to be configured to be long in the axial direction. Further, as shown in FIG. 3, coupling portions 10 a and 10 b for connecting the torsion bar 7 and the input shaft 10 are provided, or the torsion of the output shaft 20 is coupled to connect the torsion bar 7 and the output shaft 20. The torque sensor cannot be reduced in size by shortening the length in the axial direction, such as by configuring the connecting portion with the bar to be longer in the axial direction. Further, in order to ensure the same degree of coaxiality, it is necessary to provide bearings 11 and 21 such as bearings at both ends of the torsion bar 7, which increases the number of components and increases the cost. Further, when a bearing is provided, sliding friction is always generated between the shaft and the shaft, which causes a decrease in detection accuracy. However, the torque sensor of the present invention can be composed of one rotating member provided around the axis and the other rotating member arranged on the outside thereof. At the time of load detection, torque is applied to one of the two rotating members, and the connecting portion bends, whereby the load sensor is pinched between the first rotating member and the second rotating member. Then, a load sensor detects a load based on this clamping pressure. In other words, the inner rotating member and the outer rotating member appear to be slightly twisted, and the load associated with the minute twist is detected, and the load is based on the relative twist amount of the two. Is detected. Therefore, it is not necessary to be formed long in the axial direction unlike the conventional torsion bar type torque sensor, and the length in the axial length direction can be shortened. Further, since no bearing is required, the number of components can be reduced. Furthermore, the sliding friction that has occurred between the shaft and the bearing is eliminated, and the detection accuracy of the torque sensor can be increased.

  In addition, the torque sensor of the present invention has a structure in which two rotating members (first rotating member and second rotating member) are connected by a connecting portion and integrated. In the case of forming this structure, for example, the first rotating member and the second rotating member may be separately formed, and the both may be connected together by an adhesive, a screw, or the like so as to be integrally rotatable. You may use and form in the state which integrated both rotation members. As described above, the torque sensor of the present invention is formed separately as a torque sensor unit that is completely independent of other components and components other than the torque sensor by having a structure in which both rotating members are integrated. I can keep it. Generally, the torque sensor is formed by assembling each of the parts constituting the torque sensor to other components such as a rotating shaft having a gear portion. At this time, assembly requires a certain level of assembly accuracy, and there is a problem that its production capacity is low. However, if the torque sensor is completed as a torque sensor unit as in the present invention, the assembled torque sensor can be prepared in advance. All you need to do is join the parts. Therefore, it is suitable for improving the productivity of the overall mechanism including the torque sensor (for example, an electric power steering apparatus including the torque sensor on the steering shaft). In this case, if the torque sensor is previously provided with a coupling portion for coupling the torque sensor and the other mechanism, the coupling with the other mechanism is facilitated, and the productivity can be further increased.

  Moreover, since the load sensor provided in the torque sensor of the present invention is made of ceramic, it can withstand high pressure and load. Therefore, the torque sensor of the present invention can be configured so that a high pressure or a high load is applied to the load sensor, and the detection sensitivity of the load sensor can be increased. In addition, since it can withstand high pressure and high load, it is possible to reduce the area of the load application surface of the load sensor and to reduce the size. Further, the ceramic load sensor does not deform greatly even when a high load is applied. Therefore, as long as the rotating member is configured to be less rigid than the load sensor, a material with a high degree of synthesis may be used. Therefore, the entire torque sensor can be formed as a very rigid structure.

As such a ceramic load sensor, for example, a load sensor element using a ceramic and a material having a pressure resistance effect as a main material can be used. In this case, it is particularly preferable that the ceramic is zirconia and the material having a pressure resistance effect is La _1-x Sr _x MnO ₃ (0 ≦ x ≦ 1). If ceramics is zirconia, a sensor excellent in heat resistance can be obtained, and zirconia has toughness, so that a load sensor having extremely high resistance to breakage due to load and pressure can be obtained. In this case, the load sensor element has a structure in which the zirconia particles having electrical insulation are used as a matrix material, and La _1-x Sr _x MnO ₃ particles of a pressure resistance effect material are dispersed so as to be electrically continuous. Formed with. With this structure, this load sensor element changes its ohmic resistance based on the applied load and pressure, and enables load detection based on the change of the ohmic resistance.

  As a specific configuration of the torque sensor described above, for example, a first rotating member that is provided rotatably around a predetermined axis and has a protruding portion that protrudes in the radial direction from the axis, and the outside of the first rotating member, The first rotation member is coaxially connected to the first rotation member, and has an arc portion extending in the circumferential direction with respect to the axis, and in the circumferential direction, the protrusion of the first rotation member and the arc It is conceivable to include a second rotating member having an opposing surface facing a part with a gap of a predetermined interval, and a ceramic load sensor sandwiched between the first rotating member and the second rotating member in the gap. . Further, two opposing surface pairs are provided above and below the circumferential direction of the projecting portion of the first rotating member so that the projecting portion and the arc portion face each other with a predetermined gap therebetween, and a load sensor is sandwiched between the two clearances. Also good. Thereby, even if a load sensor can detect only a compression load, bidirectional torque can be detected by using two load sensors. That is, it is possible to form a torque sensor including a load detection unit capable of detecting bidirectional loads. Further, two load detection units may be provided by providing another similar load detection unit symmetrically with respect to the rotation line of the rotating member. Thereby, for example, when a malfunction occurs in the load detection unit of one system, the remaining one system can be configured to detect. In this case, in order to detect the load in a balanced manner by the two systems of detection units, the coupling unit that couples the two rotating members is arranged to extend perpendicularly from the axis to the projecting part, and as shown in FIG. Are preferably configured symmetrically. The number of systems can be further increased.

  In addition, the torque sensor of the present invention is characterized in that the two rotating members have a connecting portion that connects each other while allowing elastic deformation when torque is generated. There may be. In other words, the two rotating members can be configured to form a structure that can be integrally formed while having an elastically deformable connecting portion that allows slight torsional deformation when torque is generated. . In this case, by providing a mold or the like in advance, it is possible to easily form a structure in which two rotating members are integrally formed, and the manufacturing process can be simplified. The load sensor may be press-fitted into the gap formed in the structure. As described above, the load sensor is provided so as to be sandwiched between the first rotating member and the second rotating member so that the torque sensor can be configured so as not to cause a dead band.

In the torque sensor of the present invention, the first rotating member has a first coupling portion that is coupled to a first rotating shaft capable of transmitting rotation around the axis, and the second rotating member is around the axis. And a second coupling portion coupled to a second rotation shaft capable of transmitting the rotation of the first rotation portion, and the first coupling portion and the second coupling portion include the first rotation member and the second rotation member . It may be provided in the vicinity of the connecting portion to be connected. Specifically, the first coupling portion and the second coupling portion are provided at both ends of a coupling portion that couples the first rotating member and the second rotating member. It may be provided so that it may be pinched | interposed. Each of the first rotating member and the second rotating member of the torque sensor of the present invention is coupled to a rotating shaft. Thereby, the rotational torque input from one rotating shaft is transmitted to the other rotating shaft via two rotating members. In this case, in each rotating member, the connecting portion with the rotating shaft is a fixed end, and the side that supports the load sensor is the free end (or the side on which elastic deformation occurs). Therefore, according to the above configuration, since the coupling portion is provided near the portion connecting the two rotating members, the distance from the fixed end to the free end is increased, and the amount of elastic deformation of the free end is increased. Formed. This facilitates press-fitting of the load sensor.

  In the torque sensor of the present invention, the second rotating member may include a thin portion. By forming a part of the second rotating member thin, the second rotating member is easily elastically deformed in the direction in which the gap of the load sensor is opened, and the load sensor can be easily press-fitted.

  The electric power steering apparatus of the present invention is characterized in that the torque sensor according to any one of claims 1 to 5 is mounted on a steering shaft connected to a steering steering. An electric motor comprising a torque sensor for detecting a steering torque applied to the steering, an electric motor for generating an assist torque for assisting the steering torque, and a control unit for driving and controlling the electric motor based on the steering torque detected by the torque sensor. If the torque sensor mounted on the power steering device is the torque sensor of the present invention, the steering torque of the steering can be detected without causing a dead band or hysteresis as described above. There is no delay in assist motor control. In addition, since the torque sensor of the present invention does not have a bearing between the input / output shafts (the first rotating shaft and the second rotating shaft), sliding friction or the like does not occur, so the torque can be detected with high accuracy. Based on this, the power assist motor can be controlled. Furthermore, the torque sensor of the present invention is completed as a sensor unit independent of other components of the steering apparatus. Therefore, when assembling the electric power steering apparatus of the present invention, it is only necessary to assemble a pre-assembled torque sensor to an input / output shaft that serves as an input / output unit for rotational torque and other components, thereby improving productivity. To do.

  Hereinafter, the torque sensor of the present invention will be described with reference to the drawings. FIG. 8 schematically shows an example of an electric power steering apparatus provided with the torque sensor of the present invention. As shown in FIG. 8, the steering steering 110 is connected to a steering shaft 112a, and the lower end of the steering shaft 112a is connected to the torque sensor 1 of the present invention. The torque sensor 1 is connected to the upper end of the pinion shaft 112b. A pinion (not shown) is provided at the lower end of the pinion shaft 112b, and this pinion is meshed with the rack bar 118 in the steering gear box 116. Further, one end of a tie rod 120 is connected to both ends of the rack bar 118, and a wheel 124 is connected to the other end of each tie rod 120 via a knuckle arm 122. A power assist motor 115 is attached to the pinion shaft 112b via a gear portion (not shown), and the rotational output of the power assist motor 115 is transmitted to the pinion shaft 112b via a gear portion (not shown). Composed.

  In the electric power steering apparatus configured as described above, when the driver operates the steering steering 110, the steering steering 110 and the steering shaft 112a rotate integrally. At this time, the torque sensor 1 provided in the steering shaft 112a detects the rotational torque of the steering shaft. A steering control unit (hereinafter also referred to as ECU) 130 controls an output current to the power assist motor 115 based on detection signals from these sensors 1 and 113, detection signals from other vehicle speed sensors 117, and the like. The auxiliary force for rotating the shaft 112b is controlled. Thereby, the pinion shaft 112b rotates by the rotational force transmitted from the steering shaft 112a and the auxiliary rotational force by the motor 115, and steers the wheel 124.

  FIG. 1 is a schematic diagram showing a drive unit 50 including a torque sensor of the electric power steering apparatus 100 of FIG. As shown in FIG. 1, the torque sensor 1 is integrally provided with an intermediate portion 1b and a first coupling portion 1a that are coaxially configured, and is coupled to the input shaft 10 at the first coupling portion 1a. . At this time, the first coupling portion 1a and the input shaft 10 are provided with a hole penetrating both, and the pin 12 is press-fitted so as to penetrate the hole, so that both are coupled so as to be integrally rotatable. . The input shaft 10 is interlocked with the steering steering 110 shown in FIG. 8, and transmits the rotational torque of the steering shaft 112 a based on the operation of the steering 110 to the torque sensor 1.

  Further, the torque sensor 1 includes a second coupling portion 6 on the side opposite to the input shaft. The second coupling portion 6 is press-fitted and fixed in an opening 6 a provided in the output shaft 20 and is coupled to the output shaft 20. The output shaft 20 is formed integrally with the wheel gear 30 and is rotatably supported by bearings 21 and 22 provided on both sides of the wheel gear 30. The wheel gear 30 is engaged with a gear portion (not shown) provided on the output shaft of the power assist motor 115 (FIG. 8), and transmits the rotational output of the power assist motor 115 to the output shaft 20. The output shaft 20 transmits the rotational force of the power assist motor 115 and the rotational force transmitted from the input shaft to the pinion shaft 112b (FIG. 8) connected to the end 20a of the output shaft 20, and the wheel 124 is transmitted. Steer. The signal from the load sensor is taken out by the spiral cable 13. The spiral cable 13 is provided so as to wind around the intermediate portion 1b of the torque sensor 1 so as not to hinder the rotation of the input / output shafts 10 and 20 and the torque sensor 1.

  Hereinafter, the structure of the torque sensor of the present invention will be described with reference to FIG. FIG. 2 shows an AA ′ cross section of the torque sensor 1 shown in FIG. The torque sensor 1 includes a first rotating member 2 that is coaxially connected to the input shaft 10, and a second rotating member that is disposed so as to surround the first rotating member 2 from the outside and is coaxially connected to the output shaft 20. 4 are provided coaxially and are elastically connected by the connecting portion 3. Further, the first rotating member 2 has a protruding portion 2 a protruding in the radial direction with respect to the rotation axis, and between the upper end surface of the protruding portion 2 a and the end surface of the arc-shaped end portion 4 b of the second rotating member 4. The load sensor 51 is sandwiched, and the load sensor 52 is sandwiched between the lower end surface of the projecting portion 2 a and the end surface of the arc-shaped end portion 4 c of the second rotating member 4. At this time, the top and bottom surfaces of the projecting portion 2a of the first rotating member 2 and the end surfaces of the end portions 4b and 4c of the second rotating member 4 form opposing surfaces that face each other across the load sensors 51 and 52. The first rotating member 2 has a similar protruding portion on the opposite side of the protruding portion 2a, and load sensors 53 and 54 sandwiched between the protruding portion and the end of the second rotating member 4 are provided. Is provided. At this time, the input shaft 10, the first rotating member 2, the second rotating member 4, and the output shaft 20 are coaxially arranged around a predetermined rotating shaft as shown in FIG. Further, the connecting portion and the protruding portion are arranged so as to be perpendicular to each other, and the entire torque sensor has a symmetrical structure in the upper and lower sides and the left and right in the drawing.

  When the torque sensor 1 configured as described above receives torque from the input shaft 10, torque is transmitted to the second rotating member 4 via the first rotating member 2 and the connecting portion 3, and the second rotating member 4 An elastic displacement occurs, and the end 4b approaches the load sensor 51 to increase the compressive load, and the end 4c reduces the compressive load of the load sensor 52. Similarly, a compressive load is increased in the load sensor 53 that is diagonal to the rotation center of the load sensor 51, and a compressive load is decreased in the load sensor 54 that is diagonal to the load sensor 52. To do. At this time, the load sensors 51 to 54 input respective detection signals to the ECU 130 (FIG. 8). The ECU 130 calculates a torque value applied to the input shaft 10 based on the compressive load detected by the load sensors 51, 52, 53, and 54. Then, the assist force output from the power assist motor 115 is controlled using this torque value. In this embodiment, the load detection part which has one load sensor on both sides of the protrusion part and has a total of two load sensors is formed. Bidirectional rotational torque can be detected by looking at which load detection unit the load is increasing or decreasing. Further, in the present embodiment, since there are two projecting portions, the load detecting portion has two systems. In such a case, during normal operation, the control unit 130 controls the power assist motor 115 from the average value output by the two load detection units. If one of the systems malfunctions, the remaining one system It is desirable to be configured to function as a backup.

Next, a load sensor used for the torque sensor of this embodiment will be described. The load sensor 5 (51 to 54) of the present invention is composed of ceramic as a main material. Thereby, a load sensor that can withstand a higher load can be formed. The elements constituting the load sensor 5 include, for example, a pressure-sensitive body configured by using a ceramic material having electrical insulation as a matrix and dispersing particles having a pressure resistance effect in an electrically continuous manner. And an insulator covering the substrate. The pressure resistance effect material constituting the pressure sensitive substance, the perovskite structure _{(Ln 1-x Ma x)} 1-y MbO 3-z ( here 0 <x ≦ 0.5,0 ≦ y ≦ 0.2 , 0 ≦ z ≦ 0.6, Ln; rare earth element, Ma; one or more alkaline earth elements, Mb; one or more transition metal elements), (Ln _2−u Ma) having a layered perovskite structure _{1 + u} ) _1-v Mb ₂ O _7-w (where 0 <u ≦ 1.0, 0 ≦ v ≦ 0.2, 0 ≦ w ≦ 1.0, Ln; rare earth element, Ma; one type or A material composed of at least one of alkaline earth elements (Mb; one or more transition metal elements), Si and substances obtained by adding a trace amount of additive elements to these elements can be used. The matrix materials include zirconia (ZrO ₂ ), Al ₂ O ₃ , MgAl ₂ O ₄ , SiO ₂ , 3Al ₂ O ₃ .2SiO ₂ , Y ₂ O ₃ , CeO ₂ , La ₂ O ₃ , Si _3. N ₄ or the like can be used. In the present embodiment, zirconia (ZrO ₂ ) having high strength at room temperature and high fracture toughness is used. In addition, since the description regarding the structure and forming material of a pressure sensitive body has already been described in the said patent document 1, Unexamined-Japanese-Patent No. 2001-242019, Unexamined-Japanese-Patent No. 2002-145664, etc., detailed description here is refrained.

In this case, it is also effective to use ceramics as the main material for the insulator covering the pressure sensitive body, similarly to the pressure sensitive body. Use zirconia (ZrO ₂ ), Al ₂ O ₃ , MgAl ₂ O ₄ , SiO ₂ , 3Al ₂ O ₃ .2SiO ₂ , Y ₂ O ₃ , CeO ₂ , La ₂ O ₃ , Si ₃ N _4, etc. Is also possible. In the present embodiment, the insulator is assumed to use a zirconia (ZrO ₂₎ was added to a pressure-resistance material within a range that does not have the same zirconia (ZrO ₂₎ or electrical continuity with the pressure sensitive element.

  In the load sensor, since the element configured as described above is pressurized by applying a load and the ohmic resistance changes based on the pressure, the load can be detected based on the change in the ohmic resistance. .

  Next, a method for assembling the drive unit 50 including the torque sensor of the present invention shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 4, the drive unit 50 provided in the electric power steering apparatus of the present invention includes a gear unit 30 ′, a torque sensor unit 1 ′, and further a spiral cable 13 and an input shaft 10. In this case, the spiral cable 13 is arranged so as to be wound around the intermediate portion 1b of the torque sensor unit ', and the input shaft engages with the first coupling portion 1a of the torque sensor unit 1', and is in a predetermined position as shown in FIG. The pins 12 are press-fitted into the holes provided in the two so that they can be integrally rotated. Further, since the gear unit 30 ′ and the torque sensor unit 1 ′ can be separately formed as independent units, they can be easily combined simply by assembling completed units. In this case, the second coupling portion 6 of the torque sensor unit 1 'is press-fitted and assembled into the coupling hole 6a provided in the output shaft 20 of the gear unit 30'.

  The present invention is not limited to the above-described embodiment, and various modifications or improvements can be added without departing from the technical scope based on the description in the claims. Hereinafter, an example is shown as an embodiment different from the above embodiment.

  FIG. 5 has a configuration different from that of FIG. 1, and in this case, the second rotating unit 4 is coupled to the input shaft 10. It is the schematic which shows the drive part 50 of FIG. Also in this case, the torque sensor unit 1 'is in a state where the input shaft 10 and the torque sensor 1 are connected as shown in FIG. In the same manner as the connection between the torque sensor 1 and the output shaft 20 in FIG. 1, the input shaft 10 and the torque sensor 1 are press-fitted into a coupling hole 6a provided in the input shaft. Are connected. 6 is a cross-sectional view of the torque sensor shown in FIG. As shown in FIG. 6, the output shaft 20 and the torque sensor 1 are composed of an external gear 20 c provided at the protruding portion of the output portion and a serration 20 d provided in the opening of the rotation center portion of the torque sensor 1. They are fixed so as to mesh with each other, and both are coupled so as to be integrally rotatable.

  The torque sensor of the present invention sets the direction in which torque is applied, such as the input shaft 10 to which torque is input and the output shaft 20 to which torque applied to the input shaft is transmitted, as in the above embodiment. There is no need, and the torque sensor 1 can detect the load in the same manner regardless of whether the torque is applied from the input shaft 10 or the output shaft 20.

  Further, in the embodiment of the torque sensor of the present invention, the second rotating portion has a circular arc shape, but may have a U shape. Specifically, the second rotating member is composed of two U-shaped members, and is provided with the opening sides of the two U-shaped members facing each other and sandwiching the opening of the U-shaped member. Between the two protrusions and the same two protrusions of the other member, the protrusion of the first rotating member is sandwiched, and the protrusion of the first rotating member and the second rotation A gap having a predetermined width for sandwiching the load sensor may be provided between the U-shaped protrusions of the member. Further, for example, as shown in FIG. 7, the second rotating member 4 is formed with a notched portion 4 a in which a part of the arc portion is notched, and the radial width is narrowed, whereby the rigidity of the second rotating member 4 itself is increased. By lowering and forming a part of the second rotating member thin, the second rotating member is easily elastically deformed in the direction in which the gap of the load sensor is opened, and the load sensor can be easily press-fitted.

  In addition, the said embodiment is shown as an illustration to the last, and this invention is not limited to these embodiment. Various modifications or improvements can be added to the present invention without departing from the technical scope based on the description of the claims.

Schematic which shows 1st Embodiment of the drive part containing the torque sensor of this invention. Schematic showing the AA cross section of FIG. Schematic diagram showing a conventional torque sensor using a torsion bar and its peripheral structure Schematic showing a method of assembling the torque sensor of the present invention to the peripheral structure Schematic which shows 2nd Embodiment of the drive part containing the torque sensor of this invention. Schematic showing the BB 'cross section of FIG. Schematic which shows 3rd Embodiment of the torque sensor of this invention. The schematic diagram which shows typically one Embodiment of the electric power steering apparatus provided with the torque sensor of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torque sensor 1a 1st coupling | bond part 2 1st rotation member 3 Connection part 4 2nd rotation member 5 (51-54) Load sensor 6 2nd coupling | bonding part 10 Input shaft 20 Output shaft 30 Wheel gear 100 Electric power steering apparatus 110 Steering Steering 112a Steering shaft 112b Pinion shaft 130 Steering control unit (ECU)

Claims (5)

The first rotating member and the second rotating member are provided coaxially around a predetermined axis and are connected to each other and have opposing surfaces facing each other with a predetermined gap in the circumferential direction of the axis. Two rotating members, and a ceramic load sensor sandwiched between the two rotating members in the gap, and when torque is generated between the two rotating members, the two rotating members are The opposing surfaces approach each other by twisting each other in the direction, and the load sensor detects a load by being compressed based on the approach of the opposing surface ,
The torque sensor according to claim 1, wherein the two rotating members have a connecting portion that connects each other while allowing elastic deformation when the torque is generated . The torque sensor according to claim 1 , wherein the load sensor is press-fitted into the gap. The first rotating member has a first coupling portion that is coupled to a first rotating shaft capable of transmitting rotation around the axis, and the second rotating member is capable of transmitting rotation around the axis. A second coupling portion coupled to the shaft, and the first coupling portion and the second coupling portion are connected to both ends of the coupling portion that couples the first rotating member and the second rotating member; The torque sensor according to claim 1 , wherein the torque sensor is provided so as to sandwich the connecting portion . Said second rotary member, the torque sensor according to any one of claims 1 to claim 3, characterized in that it comprises a thin portion. An electric power steering apparatus comprising the torque sensor according to any one of claims 1 to 4 mounted on a steering shaft connected to a steering steering.

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