JP2013011515A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor whose temperature compensation accuracy is enhanced by reducing the influences of distortion due to torque inputs and distortion due to centrifugal force on a temperature compensator configured of a resistor or the like.SOLUTION: A torque sensor comprises a torque transmission shaft 2 that has a hollow shaft shape and transmits torque while entailing a twist between the driving side and the driven side, a distortion detector 40 that is fitted to an inner circumferential face 2a of the torque transmission shaft 2 and outputs a detection signal corresponding to any distortion inflicted on the inner circumferential face 2a by a torque input to the torque transmission shaft 2, a temperature compensating resistor 41 as a temperature compensator for correcting and eliminating any detection error contained in the detection signal as a result of temperature-deriving variation of the elasticity coefficient of the torque transmission shaft 2, and an installation member 9 having an equal characteristic to the temperature characteristic of the elasticity coefficient of the torque transmission shaft 2. The installation member 9 is fitted to the inner circumferential face 2a of the torque transmission shaft 2 in a facial contact state with an adhesive 91 in-between, and the temperature compensating resistor 41 is fitted to this installation member 9 in its region closer to the inner circumference than the distortion detector 40.

Description

  The present invention relates to a torque sensor using a strain detection unit such as a strain gauge, and more particularly to a torque sensor that optimizes correction of a detection error included in a detection result of a strain detection unit due to a temperature change.

  2. Description of the Related Art Conventionally, a torque sensor that detects torque acting on a shaft of a driving device such as a motor that is rotationally driven by electromagnetic action is known. For example, Patent Document 1 discloses a coupling that transmits a torque while being twisted between the drive side and the load side, having a hollow shaft shape and both axial ends connected to the shaft of the drive device and the shaft of the load device, respectively. A torque transmission shaft and a strain detection unit such as a strain gauge that is attached to the inner peripheral surface of the torque transmission shaft and outputs a detection signal corresponding to the strain generated on the inner peripheral surface by torque input, and a detection signal from the strain detection unit Discloses a strain gauge type torque sensor for calculating the magnitude of torque acting on the torque transmission shaft.

  Specifically, a strain detector using a strain gauge changes its resistance value due to the strain, and outputs a change in resistance value caused by the strain of the strain detector as a detection signal (differential voltage). A bridge circuit is configured, and a detection signal (differential voltage) corresponding to distortion is obtained by applying an excitation signal (excitation voltage) to the bridge circuit, and a torque signal is obtained based on the detection signal (differential voltage). It is customary to configure the size to be calculated.

  However, since the longitudinal elastic modulus (Young's modulus) of the torque transmission shaft changes according to changes in temperature, the amount of strain that appears on the torque transmission shaft changes even when the same torque (stress) is applied, and the strain detection unit detects it. It is known that a detection error due to a temperature change of the elastic modulus is included in the signal.

  As one effective means for correcting this detection error, in Patent Document 2, a temperature compensation unit composed of a resistance whose resistance value changes according to temperature is provided together with a strain detection unit, and this temperature compensation unit reduces the detection error. A technique for obtaining a detection signal corrected in the direction of elimination is disclosed. Patent Document 2 discloses an example of applying to a load cell instead of a torque sensor, but it is considered effective to apply this to a torque sensor.

Japanese Patent Laid-Open No. 51-131777 Japanese Utility Model Publication No. 5-50332

  The temperature compensation resistor as the temperature compensation unit is also called a temperature gauge, and its resistance value changes according to the temperature, but it has sensitivity to strain as well as the strain gauge. In a torque sensor, unlike a load cell, twist due to torque input appears in the entire torque transmission shaft. Therefore, distortion due to torque input affects the temperature compensation resistance no matter which part of the torque transmission shaft is attached. Which becomes noise and the accuracy of temperature compensation is impaired.

  Further, since the torque transmission shaft expands and deforms due to the centrifugal force, distortion occurs not only by twisting but also by rotation, and this distortion becomes noise and similarly the accuracy of temperature compensation is impaired.

  The present invention has been made paying attention to such a problem, and its purpose is to improve the temperature compensation accuracy by reducing the influence of distortion caused by torque input and distortion caused by centrifugal force on the temperature compensation unit. A torque sensor is provided.

  In order to achieve this object, the present invention takes the following measures.

  That is, the torque sensor of the present invention has a hollow shaft shape and a driving force is input to one end in the axial direction and a load is input to the other end in the axial direction to transmit torque while being twisted between the driving side and the load side. A torque transmission shaft, a strain detection unit that is attached to the inner peripheral surface of the torque transmission shaft and outputs a detection signal corresponding to a strain generated in the inner peripheral surface by torque input to the torque transmission shaft, and elasticity of the torque transmission shaft A temperature compensation unit for correcting in a direction to eliminate the detection error included in the detection signal due to a temperature change of the coefficient, and based on the detection signal corrected by the temperature compensation unit, A torque sensor for calculating the magnitude of the acting torque, wherein an installation member having a characteristic equal to a temperature characteristic of an elastic coefficient of the torque transmission shaft is attached to the inner surface of the torque transmission shaft. Indirect or indirectly attached in surface contact, wherein said attach the temperature compensating unit to the site to be the inner circumferential side of the strain detecting portion of the installation member.

  The inner surface of the torque transmission shaft means a surface that forms an internal space inside the torque transmission shaft. For example, the inner peripheral surface of the torque transmission shaft or the axial end surface of the stepped portion when there is a stepped portion inside Is mentioned. Direct or indirect surface contact means that heat conduction is possible between both members by surface contact. For example, both members are brought into a surface contact state directly, or an adhesive or the like between the two members. It is mentioned that both members are indirectly in surface contact with each other. The temperature compensation unit means a component having sensitivity to temperature and strain, and examples thereof include a resistor.

  According to this configuration, the installation member has a characteristic equal to the temperature characteristic of the elastic coefficient of the torque transmission shaft, and the installation member can conduct heat from the torque transmission shaft via the surface contact portion. Even if it is attached to an installation member other than the torque transmission shaft, it becomes possible to correct the detection error included in the detection signal of the strain detection unit. Since the installation member and the torque transmission shaft are separate, the stress due to the torque input to the torque transmission shaft is less likely to act on the temperature compensation portion than when the temperature compensation portion is attached to the inner peripheral surface of the torque transmission shaft. Thus, it is possible to improve the temperature compensation accuracy by reducing the influence of distortion caused by torque input on the temperature compensation unit.

  In addition, the temperature compensation unit is also affected by the distortion generated in the member due to the centrifugal force, but is attached to a portion of the installation member that is on the inner peripheral side of the strain detection unit. The influence of centrifugal force on the temperature compensation unit can be reduced compared to the case where the temperature compensation unit is attached together with the strain detection unit on the inner peripheral surface, and the temperature compensation accuracy can be improved.

  Further, since the installation member is separate from the torque transmission shaft, the installation member can be attached to the torque transmission shaft after the temperature compensation portion is attached to the installation member, and the temperature compensation portion is attached to the torque transmission shaft. Compared with the case of directly attaching to the inner surface, the attaching operation can be simplified. In this case, it is also possible to pursue a higher speed rotation by further reducing the diameter of the torque transmission shaft.

  In order to simplify the adjustment of the load balance of the entire shaft, it is preferable that the installation member has an annular shape centering on the shaft of the torque transmission shaft.

  In order to make the temperature characteristic of the elastic coefficient of the installation member equal to the temperature characteristic of the torque transmission shaft, the installation member is preferably made of the same material as the torque transmission shaft.

  In the present invention, as described above, the installation member having the characteristic equal to the temperature characteristic of the elastic coefficient of the torque transmission shaft is provided so as to be able to conduct heat from the torque transmission shaft via the surface contact portion. Even if the portion is attached to an installation member other than the torque transmission shaft, the detection error included in the detection signal of the strain detection portion can be corrected. Since the installation member and the torque transmission shaft are separate, the influence of distortion due to torque input on the temperature compensation unit can be reduced, and the temperature compensation accuracy can be improved. In addition, since the temperature compensation unit is attached to a part of the installation member that is on the inner peripheral side of the strain detection unit, the temperature compensation unit is centrifugally separated from the temperature compensation unit as compared with the case where the temperature compensation unit is attached to the torque transmission shaft together with the strain detection unit. The influence of force can be reduced and the temperature compensation accuracy can be improved.

Sectional drawing which shows the structure of the torque sensor which concerns on one Embodiment of this invention. The figure which shows typically drive apparatuses, such as a motor, to which the torque sensor is applied. The block diagram of a fitting shaft, and the figure which shows the fitting state of a torque transmission shaft and a fitting shaft. The figure which shows typically the circuit structure containing a distortion detection part and the resistance for temperature compensation. The figure which shows the structure of the member for installation which attaches the resistance for temperature compensation. The figure which shows the torque transmission axis | shaft and installation member which concern on other embodiment of this invention. The figure which shows the torque transmission shaft and installation member which concern on embodiment other than the above of this invention.

  Hereinafter, a torque sensor according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the torque sensor Ts is a device that measures the magnitude of torque acting on the torque transmission shaft 2 interposed between the drive device and the load device, and has a substantially hollow shaft shape, and both ends in the axial direction. 2c and 2d are connected to the drive side (drive device M) and the load side (load device), respectively, and transmit torque while twisting between the drive side and load side, and the inside of the torque transmission shaft 2 A strain detector using a strain gauge that is attached to an inner peripheral surface 2a that forms an internal space SP1 and outputs a detection signal (differential signal) corresponding to a strain generated in the torque transmission shaft 2 by torque input to the torque transmission shaft 2 40, a transmission unit 30 that transmits the detection signal of the strain detection unit 40 to the outside of the torque transmission shaft 2, and a torque that acts on the torque transmission shaft 2 based on the detection signal received from the transmission unit 30 via the antenna unit 33 A torque calculation unit 31 for calculating the size, and a substantially hollow shaft shape, and fitting into the torque transmission shaft 2 on the inner peripheral side of the torque transmission shaft 2 to form a double hollow shaft together with the torque transmission shaft 2 And a shaft 8. As illustrated in FIG. 2, the torque sensor Ts includes a driving device M such as a motor provided with the torque sensor Ts by connecting the axial end 2c of the torque transmission shaft 2 and a driving force output shaft M3a (shaft). Used to make up. In the present specification, the axial direction is X, the drive side is X1, and the load side is X2.

  As shown in FIG. 1, the torque transmission shaft 2 is made of a steel material having a substantially hollow shaft shape in which an internal space SP <b> 1 is formed, and the cross-sectional shape of the inner peripheral surface 2 a is the outer periphery of the fitting shaft 8. The shape corresponds to the cross section of the surface 8b. The fitting shaft 8 is press-fitted into the internal space SP1 from the drive side X1 by an interference fit so that the outer peripheral surface 8b of the fitting shaft 8 and the inner peripheral surface 2a of the torque transmission shaft 2 are brought into contact with each other. ing. One end 2c in the axial direction of the torque transmission shaft 2 (end portion 2c on the driving side X1) is associated with the driving force output shaft M3a (shaft) of the driving device M such as a motor to be rotated by a spline connection or the like. The driving force is input, and the other axial end 2d of the torque transmission shaft 2 (the end 2d of the load side X2) is associated with the shaft of the load device by spline connection or the like, and the load is input by the load device.

As shown in FIGS. 3 (a) and 3 (c), the fitting shaft 8 is made of a resin such as a glass epoxy resin having a bottomed substantially hollow shaft shape in which a hollow space SP0 is formed. Yes. The hollow space SP0 provided inside the fitting shaft 8 is closed on the axial one end 8c side (drive side X1), while being opened on the other axial end 8d side (load side X2) through the opening 8e. Has been. In the fitted state, as shown in FIG. 1, an internal space SP1 inside the torque transmission shaft 2 in which the strain detecting unit 40 is arranged and a hollow space SP0 inside the fitting shaft 8 are arranged through the opening 8e. Communicate. The hollow space SP0 for accommodating the transmitting unit 30 in the fitting shaft 8 has an elongated shape along the axial direction, and passes through the shaft center Cn and ends of the load side X2 as shown in FIG. from part 8d (one axial end) and the first hole 8h ₁ toward the driving side X1 (axial end), as shown in FIG. 3 (a) and FIG. 3 (d), the axially X in cross-section the orthogonal lines Li conducting a second hole 8h ₂ is a through-hole along the street radially X3 are formed. These first bore 8h ₁ and the second hole 8h ₂ of are emptied by working such as drills and wire cutting. As shown in FIG. 1, in the fitted state with the torque transmission shaft 2, the protruding fitting shaft support portion 20 provided on the inner peripheral surface 2 a of the torque transmission shaft 2 and the shaft of the fitting shaft 8. The fitting shaft 8 is positioned in the axial direction by contacting the other end 8d in the direction (the end 8d on the load side X2).

As shown in FIG. 1, the strain detector 40 uses a sheet-like strain gauge that detects a minute change in mechanical dimensions as an electrical signal, and forms an internal space SP <b> 1 inside the torque transmission shaft 2. And it is affixed on the inner peripheral surface 2a along the circle centered on the axis Cn via an adhesive. The application position of the strain detection unit 40 is set on the load side X2 with respect to the fitting shaft support unit 20. In the present embodiment, the strain detectors 40 are respectively attached to positions that are symmetrical with respect to the axis Cn as a center, and the strain detectors 40 are paired or plural pairs. As shown in FIG. The parts 40a, 40b, 40c, and 40d are connected to form the Wheatstone bridge circuit 4R by a known 4-gauge method. The bridge circuit 4R, in a state in which the excitation voltage V _in can be called the excitation signal is applied, and outputs the change in the resistance value caused by the strain of the strain detecting section 40 as a differential voltage V _out can be called a detection signal. The differential voltage _Vout is a voltage having a magnitude proportional to the amount of distortion, and is a signal corresponding to the distortion.

However, the relationship between the strain ε generated in the torque transmission shaft 2, the stress σ acting on the torque transmission shaft 2, and the longitudinal elastic modulus E (Young's modulus) of the torque transmission shaft 2 is expressed by ε = σ / E. Since the elastic coefficient E changes depending on the temperature, even if the torque (that is, the stress σ) is the same, the strain amount ε that appears in the torque transmission shaft 2 changes, and this fluctuation component, that is, the detection error is detected signal. The detection accuracy is reduced by being included in the differential voltage _Vout .

Therefore, as shown in FIG. 4B, a temperature compensation resistor 41, which can be called a temperature gauge whose resistance value changes according to temperature, is connected in series to the bridge circuit 4R to eliminate detection errors. The differential voltage _Vout corrected to is output. Specifically, the temperature compensation resistor 41 realizes correction that eliminates the detection error by adjusting the voltage V1 applied to the bridge circuit 4R (that is, the strain detection unit 40) according to the temperature. For example, the differential voltage _Vout output from the bridge circuit 4R tends to increase because the longitudinal elastic modulus E decreases as the temperature increases, so that the strain ε increases and the sensitivity of the strain detector 40 increases. In this case, the resistance value of the temperature compensation resistor 41 is also increased at the same time, the voltage V1 applied to the bridge circuit 4R is decreased, the differential voltage _Vout is decreased, and the temperature effect is canceled.

  The temperature compensation resistor 41 has the same configuration as that of the strain detector 40 using a strain gauge made of metal foil or the like, and thus has sensitivity to strain. In order to reduce the influence of distortion due to torque input and distortion due to centrifugal force, as shown in FIGS. 1 and 5, a new installation member 9 is provided, and this installation member 9 is used for temperature compensation via an adhesive. A resistor 41 is attached. As shown in FIG. 5, the installation member 9 is a ring member having a circular cross section formed using the same material as that of the torque transmission shaft 2, and the material is the same as that of the torque transmission shaft 2. The torque transmission shaft 2 has a characteristic equal to the temperature characteristic of the elastic coefficient. The outer peripheral surface 9b is formed on the inner peripheral surface 2a (inner surface) of the protruding fitting shaft support portion 20 provided on the inner peripheral surface 2a of the torque transmission shaft 2, as shown in FIGS. On the other hand, it is attached in an indirect surface contact state via an adhesive 91 and is capable of heat conduction with the torque transmission shaft 2 via an adhesive 91 having elasticity and thermal conductivity. As shown in FIGS. 5 (a), 5 (b) and 5 (c), the temperature compensating resistor 41 is affixed to the inner peripheral surface 9a of the installation member 9 in a pair, and is thus distorted. It arrange | positions rather than the internal peripheral surface 2a of the torque transmission shaft 2 to which a detection part is attached. Thereby, the influence of the centrifugal force applied to the temperature compensating resistor 41 is reduced as compared with the case where the temperature compensating resistor 41 is attached to the inner peripheral surface 2a of the torque transmission shaft 2 together with the strain detecting unit 40.

  Further, as shown in FIG. 5, the inner peripheral surface 9 a of the installation member 9 is formed with a notch 9 s through which the plate-like portion 30 a of the transmission unit 30 is passed, and is in a non-contact state with the transmission unit 30. is there. In this embodiment, as shown in FIG. 5 (b), due to the limitation of the space for attaching the temperature compensation resistor 41 to the installation member 9, the direction Y1 in which the installation member 9 expands and contracts by centrifugal force and the detection direction However, the temperature compensation resistor 41 may be attached in a posture in which the direction Y1 in which the installation member 9 expands and contracts by centrifugal force and the detection direction intersect or are orthogonal to each other. . If the temperature compensation resistor 41 is attached in such a posture, it is possible to reduce the influence of distortion due to centrifugal force on the temperature compensation resistor 41.

  As shown in FIG. 1, leakage from the outer peripheral surface 2 b of the torque transmission shaft 2 to the outer peripheral surface 2 b occurs between the portion where the strain detection unit 40 and the installation member 9 are installed and the portion that contacts the bearing 5. A refrigerant swinging part 2v having a V shape is provided to prevent the refrigerant from flowing out to the load device by shaking off the remaining refrigerant with centrifugal force. Since the area for radiating the heat of the bearing 5 is increased by the refrigerant swing-off portion 2v, the temperature change in the strain detection portion 40 and the temperature compensation resistor 41 can be reduced, and the decrease in the strain amount detection accuracy is suppressed. Further, as shown in the figure, a refrigerant is injected between the outer peripheral surface 2 b of the torque transmission shaft 2 and the portion where the strain detecting unit 40 and the installation member 9 are installed to the portion contacting the bearing 5. Since the injection path 73 is provided, strain detection and temperature compensation are performed at a position where the heat of the bearing 5 is cooled by the refrigerant, so that the temperature change is suppressed and a decrease in distortion detection accuracy is suppressed. doing.

Transmission unit 30, as shown in FIGS. 1 and 3 (a), has a plate-like portion 30a such as a printed board, by applying an excitation voltage V _in serving excitation signal to the distortion detection section 40 and the strain detecting unit 40 Using a telemeter that transmits a detection signal that is a differential voltage V _out to the outside of the torque transmission shaft 2, and is disposed in the hollow space SP0 of the fitting shaft 8 and provided on the inner surface 8a of the hollow space SP0. It is held by the mounting portion 80.

  As shown in FIGS. 1 and 3A, the attachment portion 80 is a slit into which an end portion of the plate-like portion 30a of the transmission portion 30 can be inserted, and a plurality of attachment portions 80 are formed on the inner surface 8a forming the hollow space SP0. Yes. Specifically, as shown in FIGS. 3A and 3C, when the hollow space SP0 is regarded as a bottomed cylindrical hollow portion, the first attachment portion is provided on the inner surface 8a corresponding to the bottom portion. 80a is formed, and second mounting portions 80b and 80b that are paired with the inner peripheral surface 8a in the vicinity of the opening 8e are formed. The first and second mounting portions 80a and 80b are long. The transmitter 30 is supported in a both-sided state.

  As shown in FIG. 1, an antenna portion 33 is provided on the outer peripheral side of the torque transmission shaft 2. Further, outside the torque transmission shaft 2, a torque calculation unit 31 that receives the detection signal transmitted from the transmission unit 30 via the antenna unit 33 and calculates the magnitude of the torque by calculation processing, and the transmission unit 30 On the other hand, a power supply unit 32 that supplies power via the antenna unit 33 in a non-contact manner is provided.

That is, as shown in FIG. 1, power is supplied to the transmission unit 30 from the power supply unit 32 via the antenna unit 33, the excitation voltage V _in is applied to the distortion detection section 40 (see FIG. 4). When torque acts on the torque transmission shaft 2, the torque transmission shaft 2 is twisted, and this twist is detected as a strain amount by the strain detector 40 attached to the inner peripheral surface 2 a of the torque transmission shaft 2. A detection signal (differential voltage V _out ) corresponding to the amount of strain output from the strain detection unit 40 is transmitted from the transmission unit 30 to the torque calculation unit 31, and the torque calculation unit 31 determines the magnitude of the torque based on the detection signal. calculate.

  As shown in FIG. 1, the torque transmission shaft 2 is rotatably supported by a fixed support portion 6 via a bearing 5. The bearing 5 uses a rolling bearing such as a ball bearing, and a plurality (two in this embodiment) are provided along the axial direction so as to support the torque transmission shaft 2 at a plurality of places (two in this embodiment). Has been placed. Specifically, the antenna unit 33 is disposed on both sides in the axial direction.

  As shown in FIG. 1, the fixed support portion 6 has a substantially bottomed cylindrical shape, and a cylindrical support in which a base end portion 60a of the drive side X1 is attached to the housing M1 of the drive device M via a fastening device such as a bolt. Part 60 and a lid-like support part 61 that closes the opening 60k on the load side X2 of the cylindrical support part 60. The bearing 5 is arranged in the internal space SP2 formed by the cylindrical support part 60 and the lid-like support part 61, and the fixed support part 6 has the bottom part 60bt of the cylindrical support part 60 and the lid-like support part 61 in the axial direction. The torque transmission shaft 2 disposed at a position penetrating along X is supported rotatably via a bearing 5 so that the torque transmission shaft 2 and the fitting shaft 8 can rotate together. The bearing 5 includes a projecting rotation-side bearing support portion 64 a formed on the outer peripheral surface 2 b of the torque transmission shaft 2, and a fixed-side bearing support portion using the lid-like support portion 61 and the bottom portion 60 bt of the cylindrical support portion 60 as a scaffold. 64b and is fixed in the axial direction.

  As shown in FIG. 1, a refrigerant supply path 7 is provided for supplying the refrigerant introduced from the axial one end 2c side (drive side X1) of the torque transmission shaft 2 to the bearing 5 so as not to communicate with the internal space SP1. . Specifically, as shown in FIGS. 3A, 3B, and 3C, the outer peripheral surface 8b of the fitting shaft 8 is axially moved from the axial one end 8c side (drive side X1). A groove 81 extending toward the other end 8d side (load side X2) is provided, and as shown in FIGS. 1 and 3 (d), the groove portion is in the fitted state of the torque transmission shaft 2 and the fitting shaft 8. A thrust path 71 for supplying the refrigerant introduced from one side in the axial direction X to the bearing 5 is formed between 81 and the opposing surface of the groove 81 (the inner peripheral surface 2a of the torque transmission shaft 2). I have to.

  As shown in FIG. 1 and FIGS. 3A to 3C, an introduction path 70 and a connection path 72 are provided as components constituting the refrigerant supply path 7 other than the thrust path 71. The introduction path 70 is a path through which the refrigerant is introduced from the axial end 8c (drive side X1) through the axial center Cn of the fitting shaft 8 that is inside in the fitted state, and the connection path 72 is an outer periphery from the introduction path 70. This is a path that extends toward, and connects the introduction path 70 and the thrust path 71. The thrust path 71 is provided with a plurality of injection paths 73 for ejecting refrigerant to each bearing 5, and the thrust path 71 serves as a main path and the injection path 73 serves as a branch path to supply refrigerant to each bearing 5. A flow path is formed by branching from one thrust path 71. Corresponding to the injection path 73, the fixed-side bearing support portion 64b is in a position overlapping with the injection path 73 in the radial direction, and a curved guide surface 64x for guiding the refrigerant supplied from the injection path 73 to the bearing 5 is formed. Has been.

  As shown in FIG. 3D, a plurality (two in this embodiment) of the groove portions 81 are provided to form a pair, and the pair of groove portions 81 and 81 are arranged at positions that are symmetric about the axial center Cn. As shown in FIG. 1, each connection path 72 is connected to a branch portion 70 a at the tip of the introduction path 70. Thereby, the load balance in the whole axis | shaft is taken.

  As schematically shown in FIG. 2 using a conceptual diagram, the driving device M uses a well-known motor or the like, and is fixed to the housing M1 and generates a magnetic field. And a rotor M3 that is supported by the housing M1 in a rotatable state and rotates by receiving a magnetic field. The magnetic field is changed by energization control to the stator M2, and a repulsive force is generated between the stator M2 and the rotor M3. The rotor M3 is rotated by applying a suction force or the like, and the rotational driving force is output from the electric energy. The torque transmission shaft 2 is connected to the driving force output shaft M3a (shaft) of the rotor M3 so that the driving force is input to the torque transmission shaft 2, and the fixed support portion 6 is attached to the housing M1. . Further, the driving force output shaft M3a constituting the driving device M is rotatably supported by an output shaft bearing M4, and a mechanism including an output shaft bearing M4 and a heat generating unit (not shown) through the refrigerant therein. A part of the flow path M5 for supplying the refrigerant to the component is configured, and the introduction path 70 formed inside the torque transmission shaft 2 is configured such that the refrigerant is introduced from the output shaft M3a. Of course, the torque transmission shaft 2 and the driving force output shaft M3a (shaft) may be integrally formed as the same member, and the fixed support portion 6 and the housing M1 may be integrally formed as the same member. In this case, it is possible to reduce the axial dimension of the entire device including the torque sensor and the drive device. The driving device M shown in FIG. 2 is only a conceptual diagram, and is not limited to the illustrated driving device. A drive device other than a motor may be used.

As described above, the torque sensor Ts of the present embodiment has a hollow shaft shape, and a driving force is input to the one axial end 2c and a load is input to the other axial end 2d. And a detection signal (differential) corresponding to the distortion generated on the inner peripheral surface 2a by torque input to the torque transmission shaft 2 attached to the inner peripheral surface 2a of the torque transmission shaft 2 a distortion detection unit 40 for outputting a voltage V _out), the temperature for correcting the direction to eliminate the detection error included in the detection signal (differential voltage V _out) due to the temperature change of the elastic modulus of the torque transmitting shaft 2 comprising a compensator serving temperature compensating resistor 41, calculates the magnitude of the torque acting on the torque transmitting shaft 2 based on the corrected detection signal (a differential voltage V _out) by the temperature compensating unit serving temperature compensating resistor 41 A torque sensor Ts having a characteristic equal to the temperature characteristic of the elastic coefficient E of the torque transmission shaft 2 is indirectly in surface contact with the inner surface (inner peripheral surface 2a) of the torque transmission shaft 2. A temperature compensation resistor 41 serving as a temperature compensation unit is attached to a portion of the installation member 9 on the inner peripheral side of the strain detection unit 40.

  According to this configuration, the installation member 9 has a characteristic equal to the temperature characteristic of the elastic coefficient E of the torque transmission shaft 2, and the installation member 9 can conduct heat from the torque transmission shaft 2 via the surface contact portion. Therefore, even if the temperature compensation resistor 41 serving as the temperature compensation unit is attached to the installation member 9 other than the torque transmission shaft 2, the detection error included in the detection signal of the strain detection unit 40 can be corrected. Since the installation member 9 and the torque transmission shaft 2 are separate bodies, the torque applied to the torque transmission shaft 2 is compared with the case where the temperature compensation resistor 41 serving as the temperature compensation portion is attached to the inner peripheral surface 2a of the torque transmission shaft 2. It becomes difficult for the stress due to the input to act on the temperature compensation resistor 41, and the influence of the distortion caused by the torque input on the temperature compensation resistor 41 can be reduced to improve the temperature compensation accuracy.

  In addition, the temperature compensation resistor 41 serving as the temperature compensation unit is also affected by the distortion generated in the member due to the centrifugal force, but is attached to a portion of the installation member 9 that is on the inner peripheral side of the strain detection unit 40. Therefore, the effect of centrifugal force on the temperature compensation resistor 41 can be reduced and temperature compensation accuracy can be improved compared to the case where the temperature compensation resistor 41 is attached to the inner peripheral surface 2a of the torque transmission shaft 2 together with the strain detector 40. It becomes possible.

  Further, since the installation member 9 is separate from the torque transmission shaft 2, the installation member 9 is attached to the torque transmission shaft 2 after the temperature compensation resistor 41, which is a temperature compensation unit, is attached to the installation member 9. As compared with the case where the temperature compensating resistor 41 is directly attached to the inner surface of the torque transmission shaft 2, the attaching operation can be simplified. In this case, the torque transmission shaft 2 can be further reduced in diameter to pursue high speed rotation.

  In particular, in the present embodiment, the installation member 9 has an annular shape centering on the axis Cn of the torque transmission shaft 2, so that it is possible to simplify the adjustment of the load balance of the entire shaft.

  Furthermore, in this embodiment, since the installation member 9 is made of the same material as the torque transmission shaft 2, the temperature characteristic of the elastic coefficient E of the installation member is the temperature characteristic of the elastic coefficient E of the torque transmission shaft 2. It is possible to attach the temperature compensation resistor 41 as the temperature compensation unit.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is shown not only by the above description of the embodiments but also by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the present embodiment, the torque sensor Ts is configured to be incorporated in the drive device M, but may be configured alone. In this embodiment, the temperature compensation unit is a resistor, but may be other than a resistor as long as it has sensitivity to temperature and strain.

  In this embodiment, the installation member 9 is made of the same material as that of the torque transmission shaft 2. However, if the temperature characteristics of the elastic coefficients of the installation member and the torque transmission shaft 2 are equal, they are not made of the same material. May be.

  Further, in the present embodiment, the installation member 9 is attached to the torque transmission shaft 2 in a surface contact state via an adhesive, but is directly attached without using an adhesive or the like. The member 9 may be directly attached to the torque transmission shaft 2 in a surface contact state. Moreover, when making surface contact indirectly, it is not limited to an adhesive agent as a member to interpose.

  In order to connect the torque transmission shaft and the installation member so as to be able to conduct heat, a method other than the fitting or bonding as in the present embodiment may be used. For example, as shown in FIG. 6A, screw grooves vv corresponding to each other are provided on the inner peripheral surface of the torque transmission shaft 102 and the outer peripheral surface of the installation member 109, and fastening means such as a screw groove vv are used. For example, the torque transmission shaft 102 and the installation member 109 may be fixed in a surface contact state.

  In addition, as shown in FIG. 6B, a projecting stepped portion 220 is formed on the inner peripheral surface of the torque transmission shaft 202, and the installation member 209 is pressed against the axial end surface 220 c of the stepped portion 220. A pressing means vp1 such as a retaining ring may be provided, and the installation member 209 may be attached to the inner surface 220c of the torque transmission shaft 202 in a surface contact state.

  Further, as shown in FIG. 6 (c), a projecting stepped portion 320 is formed on the inner peripheral surface of the torque transmission shaft 302, and a C-shape (partially broken annular) is formed by abutting the ends. The installation member 309 is fitted to the inner peripheral surface of the torque transmission shaft 302 in a state where the elastic repulsion force is accumulated, and the outer peripheral surface of the installation member 309 is caused to be the inner periphery of the torque transmission shaft 302 by the elastic repulsion force of the installation member 309. The installation member 309 may be attached to the inner surface of the torque transmission shaft 302 in a surface contact state so as to be pressed against the surface.

  In addition, when a plurality of temperature compensation resistors 41 are provided, an installation member may be provided for each temperature compensation resistor 41.

  In this embodiment, the installation member 9 to which the temperature compensation resistor 41 is attached has an annular shape, but the shape is not limited to this. For example, as shown in FIG. 7, a plate surface 409i is formed on the installation member 409, a temperature compensating resistor 41 is attached to the plate surface 409i, and the installation member 409 is torqued with a fastening tool vo such as a screw. For example, the transmission shaft 402 may be fixed in a surface contact state. When the temperature compensation resistor 41 is attached to a curved surface, the temperature compensation resistor 41 is attached in a bent state, and distortion is detected in the offset state, but the temperature compensation resistor is thus formed on the plate surface 409i. When 41 is attached, the temperature compensation resistor 41 can be attached with little or no deflection, and distortion detected in the offset state can be reduced or eliminated, and offset adjustment is simplified. It becomes possible to do.

  The specific configuration of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

2 ... Torque transmission shaft 2c ... One axial end 2d ... Other axial end 2a ... Torque transmission shaft inner peripheral surface 40 ... Strain detection units 40a, 40b, 40c, 40d ... Strain detection unit 41 ... Temperature compensation unit (for temperature compensation) resistance)
9 ... Installation member X1 ... Drive side X2 ... Load side E ... Elastic coefficient (longitudinal elastic coefficient)
V _out ... Detection signal (differential voltage)

Claims (2)

A torque transmission shaft that has a hollow shaft shape and a driving force is input to one axial end and a load is input to the other axial end to transmit torque while being twisted between the driving side and the load side; and the torque transmission shaft A strain detector that outputs a detection signal corresponding to a strain generated in the inner peripheral surface by torque input to the torque transmission shaft, and a temperature change of an elastic coefficient of the torque transmission shaft. A temperature compensation unit for correcting in a direction to eliminate the detection error included in the detection signal, and calculating a magnitude of torque acting on the torque transmission shaft based on the detection signal corrected by the temperature compensation unit. A torque sensor,
An installation member having a characteristic equal to the temperature characteristic of the elastic coefficient of the torque transmission shaft is attached in a surface contact state directly or indirectly to the inner surface of the torque transmission shaft, and the strain detection among the installation members. A torque sensor, wherein the temperature compensation unit is attached to a portion that is on the inner peripheral side of the unit.   The torque sensor according to claim 1, wherein the installation member has an annular shape centering on an axis of the torque transmission shaft.

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