Torque detector

Abstract

To provide a new distortion sensitive resistor on which work such as soldering can be easily performed, and a new torque detector improved in a rigidity degree of a rotation shaft by loading the distortion sensitive resistor.SOLUTION: A distortion sensitive resistor 1 is provided with two sensitive elements 3A, 3B and three terminal parts 6a-6c arranged in one step side by side. The sensitive element 3A is provided between the terminal part 6a and the terminal part 6c, and the sensitive element 3B is provided between the terminal part 6b and the terminal part 6c. The sensitive elements 3A, 3B are not provided on a +Y-direction side or a -Y-direction side of the terminal parts 6a-6c. Use of the distortion sensitive resistor 1 reduces an axial length of a distortion producing part provided on a rotation shaft of the torque detector.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a strain-sensitive resistor attached to a strain-flexing part that elastically deforms, and a torque detector including the strain-sensitive resistor. [Background technology]

[0002] Various techniques for detecting the torque of a rotating shaft have been proposed. One of these proposed techniques uses a strain-sensitive resistor to directly measure the torsion of the rotating shaft. In this technique, a thin-walled strain-sensitive part is provided on the rotating shaft, and a strain-sensitive resistor is attached to the strain-sensitive part. The torque of the rotating shaft is detected by measuring the resistance value when the strain-sensitive resistor is deformed in accordance with the torsion of the strain-sensitive part.

[0003] Here, the shape of the strain-sensitive resistor attached to the strain generating body to detect the torque of the rotating shaft is such that it can accurately detect not only the torsion of the shaft rotating in one direction but also the torsion of the shaft rotating in the opposite direction, and so a strain-sensitive resistor as shown in FIG. 7 of Patent Document 1 is generally used (hereinafter referred to as the "conventional example"). The strain-sensitive resistor (strain gauge) of this conventional example has two sensitive elements (strain detection units) whose maximum sensitivity directions intersect at 90 degrees, and four terminal parts. The two sensitive elements are arranged side by side with no gap between them so as to face each other symmetrically with respect to the center line direction. Furthermore, two terminal parts are drawn out from each sensitive element, and these terminal parts are arranged in a row different from the row in which the sensitive elements are arranged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-77172 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional strain-sensitive resistor, two sensing elements and a plurality of terminals are arranged in two rows symmetrically with respect to the center line direction of the shaft, and the structure is long when the center line direction is taken as the vertical direction. As a result, in the conventional strain-sensitive resistor, the distance between the terminals drawn from the sensing elements tends to be narrow. As a result, there are cases where skilled techniques are required for the soldering work between the terminals. In addition, in the conventional strain-sensitive resistor, the length of the strain-sensitive resistor tends to be long in the center line direction, so the axial length of the strain-generating body to which the strain-sensitive resistor is attached also tends to be long. For this reason, there has been a demand for suppressing the axial length of the strain-generating body in the rotating shaft from becoming long, thereby increasing the rigidity of the rotating shaft.

[0006] In addition, the terminals of the strain-sensitive resistor are soldered after the resistor is attached to the strain-generating body of the rotating shaft. If a strain-sensitive resistor with a narrow distance between its terminals is attached to a strain-generating body that is long in the axial direction and then soldered, heat is likely to escape during soldering, which is also expected to make the soldering work more time-consuming.

[0007] As a result, the conventional strain-sensitive resistor has a problem that it is difficult to solder between the terminals, and a problem that it is necessary to suppress the axial length of the strain-generating body to which the strain-sensitive resistor is attached and increase the rigidity of the rotating shaft, and there is room for improvement. Therefore, a technology that can improve these problems is desired. Meeting such a demand is one of the problems that the present invention must solve.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a new strain-sensitive resistor that is easy to solder and other operations, and a new torque detector in which the strain-sensitive resistor is attached to improve the rigidity of the rotating shaft. [Means for solving the problem]

[0009] From a first perspective, the present invention provides a strain-sensitive resistor comprising two sensory elements having a folded pattern for detecting strain formed by a resistor, and a plurality of terminal portions each extending from each of the sensory elements by wiring, the sensory elements and the terminal portions being arranged alternately on the same plane.

[0010] In this strain sensitive resistor, each sensing element and a plurality of sensing elements are arranged alternately on the same surface, which makes it easy to solder lead wires to each terminal portion.

[0011] In addition, in the strain-sensitive resistor of the present invention, the two sensory elements are a first sensory element and a second sensory element, and the multiple terminal portions include a first terminal portion extended from one end side of the first sensory element, a second terminal portion extended from one end side of the second sensory element, and a third terminal portion extended from the other end side of the first sensory element and the other end side of the second sensory element.

[0012] In this case, for example, the first terminal portion extended from the first sensory element, the first sensory element, the third terminal portion extended from the first sensory element and the second sensory element, the second sensory element, and the second terminal portion extended from the second sensory element can be arranged in that order on the same plane.

[0013] In addition, in the strain-sensitive resistor of the present invention, the direction in which the folded pattern of the first sensor element extends and the direction in which the folded pattern of the second sensor element extends can be made to intersect at a predetermined angle, so that the direction of maximum sensitivity for strain detection of the first sensor element and the direction of maximum sensitivity for strain detection of the second sensor element can be made to intersect at a predetermined angle, thereby making it possible to detect torsion of the rotating shaft in both directions.

[0014] From a second viewpoint, the present invention provides a method for detecting a distortion of a semiconductor device, comprising: a first sensory element having a folded pattern for detecting distortion formed by a resistor; a second sensory element having a folded pattern for detecting distortion formed by a resistor; a first terminal portion drawn out from one end side of the first sensory element; a second terminal portion drawn out from one end side of the second sensory element; and a third terminal portion drawn out from the other end side of the first sensory element and the other end side of the second sensory element, for connecting the first sensory element and the second sensory element; the first sensory element and the second sensory element, as well as the first terminal portion, the second terminal portion and the third terminal portion are arranged in parallel on the same plane along one direction, the third terminal portion is arranged between the first sensory element and the second sensory element arranged in parallel, the first terminal portion is arranged on a side of the first sensory element on which the third terminal portion is not arranged, and the second terminal portion is arranged on a side of the second sensory element on which the third terminal portion is not arranged.

[0015] In this strain sensitive resistor, each sensor element including a first sensor element and a second sensor element, and each terminal portion including a first terminal portion, a second terminal portion, and a third terminal portion are arranged in parallel on the same plane along one direction. Since the first sensor element is disposed between the first terminal portion and the second terminal portion, the first terminal portion and the second terminal portion are not close to each other. Furthermore, since the second sensor element is disposed between the second terminal portion and the third terminal portion, the second terminal portion and the third terminal portion are not close to each other.

[0016] Therefore, according to the strain sensitive resistor of the present invention, soldering of lead wires to the first, second and third terminal portions becomes easy.

[0017] In order to achieve the above object, the present invention provides A torque detector that includes a strain-generating part and a strain-sensitive resistor and detects a torsional torque of a rotating shaft of a motor part, The strain generating part is It is provided in the thin-walled portion in the axial middle of the rotating shaft and is elastically deformed by torsional torque. The strain sensitive resistor is Two sensing elements having a folded pattern for detecting distortion formed by a resistor; The Each sensor element is connected to a wire. Three Terminal part and are defined as regions on the same surface extending along the axial direction of the rotation shaft with a predetermined width. A substrate is provided, The above-mentioned substrate is attached to the exposed flat surface of the thin-walled portion at the strain generating portion, The sensing elements and terminal parts provided as the above-mentioned regions are each A step extending in a predetermined width in the middle of the inner side from the edge of the base material is a part related to the configuration of a step arrangement in which a plurality of steps are adjacent to each other as a half region along a direction perpendicular to the axial direction, In addition, each region related to the stepwise arrangement corresponds to each alternating half region in which the sensing elements are arranged in parallel between the terminal parts, One or the other of the three half regions of the terminal portion in the axial direction is A plus side region that extends from one side end of the half region to one edge of the substrate along a predetermined width without a folded pattern of the sensing element being arranged thereon; Or a minus side region that extends from the other side end of the half region to the other edge of the substrate along a predetermined width without the folded pattern of the sensing element being arranged; and are on the same plane.

[0018] In order to achieve the above object, the present invention provides A force detector including a strain-generating part and a strain-sensitive resistor, the force detector detecting a force applied to the strain-generating part, The strain generating part is Force Application Elastic deformation occurs due to the shear action caused by provided in the thin-walled portion of the elastic body, The strain-sensitive resistor is Two sensing elements having a folded pattern for detecting distortion formed by a resistor; The Each sensor element is connected to a wire. Three Terminal part and The areas are defined as regions on the same surface that extend to a predetermined width along the first direction in which shear occurs and the second direction perpendicular to the first direction in which shear occurs when the strain-generating part is expanded in a virtual plan view. A substrate is provided, The above-mentioned substrate is attached to the exposed flat surface of the thin-walled portion at the strain generating portion, The sensing elements and terminal parts provided as the above-mentioned regions are each A step extending in a predetermined width in the middle of the base material from the edge of the base material is a part related to a configuration of a step arrangement in which a plurality of steps are adjacent to each other as a half region along the first direction, In addition, each region related to the stepwise arrangement corresponds to each alternating half region in which the sensing elements are arranged in parallel between the terminal parts, One or the other of the three half regions of the terminal portion in the second direction is A plus side region that extends from one side end of the half region to one edge of the substrate along a predetermined width without a folded pattern of the sensing element being arranged thereon; Or a minus side region that extends from the other side end of the half region to the other edge of the substrate along a predetermined width without the folded pattern of the sensing element being arranged; and are on the same plane.

[0019] Therefore, the torque detector of the present invention can improve the rigidity of the rotating shaft, and also facilitates soldering of lead wires to each terminal of the strain sensitive resistor attached to the torque detector.

[0020] In the torque detector of the present invention, the sensitive elements and the terminals can be arranged in a direction perpendicular to the axial direction of the rotating shaft, so that the axial length of the strain generating body in the rotating shaft can be shortened to the maximum while the direction of maximum sensitivity of the strain detection of the first sensitive element and the direction of maximum sensitivity of the strain detection of the second sensitive element can be set to the optimum state.

[0021] In the torque detector of the present invention, the number of the strain-sensitive resistors may be two or more, and each of the strain-sensitive resistors may be attached to a different flat portion formed on the strain-generating part. In this case, it is possible to reduce detection errors due to temperature changes, etc. Effect of the Invention

[0022] As described above, the strain-sensitive resistor of the present invention has the effect of facilitating soldering and other operations and improving the convenience of the worker, while the torque detector of the present invention has the effect of improving the rigidity by attaching the strain-sensitive resistor. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a plan view of a strain-sensitive resistor according to an embodiment of the present invention. [Diagram 2] 1 is an external view of a torque detector according to an embodiment of the present invention; [Diagram 3] FIG. 3 is a cross-sectional view of the torque detector of FIG. 2. [Figure 4] FIG. 3 is an external view of the torque detector in FIG. 2 with some components such as a flange omitted. [Diagram 5] 3 is a diagram for explaining a strain-generating part of the torque detector in FIG. 2 and a strain-sensitive resistor attached to the strain-generating part. FIG. [Figure 6]3 is a cross-sectional view of a strain-generating portion for illustrating a strain-sensitive resistor attached to the strain-generating portion of the torque detector of FIG. 2. [Figure 7] 1 is a diagram showing the configuration of a Wheatstone bridge circuit including a strain-sensitive resistor of a force detector according to an embodiment of the present invention, and its surroundings. [Figure 8] FIG. 3 is a diagram (part 1) for explaining the state of a strain-flexing part when the rotation shaft of the torque detector in FIG. 2 is twisted. [Figure 9] FIG. 3 is a diagram (part 1) for explaining the state of a strain-flexing part when the rotation shaft of the torque detector in FIG. 2 is twisted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same or equivalent elements are designated by the same reference numerals, and duplicated description will be omitted.

[0025] [Structure of strain-sensitive resistor 1] FIG. 1 shows a plan view of a strain-sensitive resistor 1 according to an embodiment. The coordinate system (X, Y) in FIG. 1 is defined as shown in the figure. As shown in FIG. 1, the strain-sensitive resistor 1 has a resistor and wiring patterned on a film-like substrate 2 serving as a base, and includes sensitive elements 3A and 3B, wiring parts 5a to 5c, and terminal parts 6a to 6c. That is, the sensitive elements 3A and 3B, the wiring parts 5a to 5c, and the terminal parts 6a to 6c are disposed on the substrate 2 (on the same surface). Here, the sensitive element 3A corresponds to the first sensitive element, and the sensitive element 3B corresponds to the second sensitive element. Also, the terminal part 6a corresponds to the first terminal part, the terminal part 6b corresponds to the second terminal part, and the terminal part 6c corresponds to the third terminal part.

[0026] In this embodiment, the substrate 2 is, for example, a dielectric polyimide film. The two sensing elements 3A, 3B, the wiring parts 5a to 5c, and the terminal parts 6a to 6c are made of metal, for example, an alloy of copper and nickel. If necessary, the sensing elements 3A, 3B, the wiring parts 5a to 5c, etc. may be covered with a protective layer 7 from above.

[0027] Here, the protective layer 7 is, for example, a polyimide resin, and is formed by applying a liquid or adhering a film. In this embodiment, the protective layer 7 is formed in the entire region of the base material 2 except for the rectangular portions 7a to 7c. By providing such a protective layer 7, it is possible to prevent mechanical damage, etc. from occurring to the sensory elements 3A and 3B, and also to protect the sensory elements 3A and 3B from moisture, etc. The protective layer 7 can be formed of insulating resins such as epoxy resin, PEEK resin, PET resin, PPS resin, etc., in addition to polyimide resin. The thickness of the protective layer 7 can be, for example, about several μm to 30 μm.

[0028] The sensory elements 3A and 3B are configured to include a folded pattern of a plurality of linear resistors arranged in parallel for strain detection, and the resistors have a relatively small line width. The sensory element 3A is arranged on the +X direction side of the substrate 2, and the sensory element 3b is arranged on the -X direction side of the substrate 2. A terminal portion 6c is arranged between the sensory elements 3A and 3B.

[0029] The resistors of the sensing element 3A are arranged in parallel in the direction A at -45 degrees with a narrow line width that allows them to detect distortion with maximum sensitivity in that direction in the XY coordinate system. The length of the sensing element 3A in the distortion detection direction gradually increases from one end, wiring section 5a, and then gradually decreases toward the other end, wiring section 5c. The ends of these adjacent resistors are folded back and connected by end tabs.

[0030] The resistors of the sensing element 3B are arranged in parallel in the +45° direction B with a narrow line width that allows them to detect distortion with maximum sensitivity in the +45° direction B in the XY coordinate system. The length of the sensing element 3B in the distortion detection direction also gradually increases from the wiring portion 5b on one end side, and then gradually decreases toward the wiring portion 5c on the other end side. The ends of these adjacent resistors are folded back and connected by end tabs.

[0031] Thus, the strain-sensitive resistor 1 in this embodiment is a shear-type biaxial strain-sensitive resistor 1, in which the maximum sensitivity directions for detecting strain between the sensing elements 3A and 3A intersect at a predetermined angle of 90 degrees, and are symmetrically arranged on the same substrate 2 with respect to the Y-axis direction.

[0032] The wiring sections 5a to 5c are electrically connected to the sensory elements 3A and 3B to wire signals, and have a line width thick enough not to detect distortion. The wiring section 5a is connected to one end of the sensory element 3A to wire signals. The wiring section 5b is connected to one end of the sensory element 3B to wire signals. The wiring section 5c is electrically connected to the other end of the sensory element 3A and the other end of the sensory element 3B.

[0033] The terminal portion 6a is an extension from the wiring portion 5a and is disposed on the +X direction side of the sensory element 3A. The terminal portion 6b is an extension from the wiring portion 5b and is disposed on the -X direction side of the sensory element 3B. The terminal portion 6c is an extension from the wiring portion 5c and is disposed between the sensory elements 3A and 3B.

[0034] The protective layer 7 is not formed on the rectangular portion 7a of the terminal portion 6a, the rectangular portion 7b of the terminal portion 6b, and the rectangular portion 7c of the terminal portion 6c. Therefore, the metals extending from the wiring portions 5a to 5c are exposed on the terminal portions 6a to 6c. Lead wires or the like can be connected to the terminal portions 6a to 6c by soldering or the like.

[0035] Thus, in the strain-sensitive resistor 1 according to this embodiment, the two sensing elements 3A, 3B and the three terminals 6a to 6c are arranged in a row in the X direction. The sensing element 3A is arranged between the terminals 6a and 6c, and the terminals 6a and 6c are not close to each other. The sensing element 3B is arranged between the terminals 6b and 6c, and the terminals 6b and 6c are not close to each other. This makes it easier to solder lead wires to the terminals 6a to 6c.

[0036] In addition, in the strain-sensitive resistor 1 according to this embodiment, the sensitive elements 3A, 3B are not disposed on the +Y direction side or the -Y direction side of each of the terminals 6a to 6c. Therefore, when soldering the lead wires to the terminals 6a to 6c, the lead wires can be drawn out either to the +Y direction side or to the -Y direction side.

[0037] Moreover, in the strain-sensitive resistor 1 according to this embodiment, the sensitive elements 3A, 3B and the terminal portions 6a to 6c are arranged in a single row in the X direction, so that the length in the Y direction is short.

[0038] [Configuration of torque detector 10] 2 to 5 show external views of a torque detector 10 according to an embodiment including a strain-sensitive resistor configured similarly to the strain-sensitive resistor 1 described above. The coordinate system (U, V, W) in FIGS. 2 to 5 is defined as shown. Here, FIG. 2 is a perspective view of the torque detector 10. Also, FIG. 3 is a cross-sectional view of the torque detector 10 cut along a plane P passing through the rotation axis shown in FIG. 2. Also, FIG. 4 is a perspective view of the inside of the torque detector 10 shown in FIG. 2. Furthermore, FIG. 5 is an enlarged view (VW plan view) of a portion of the torque detector 10 shown in FIG. 4 on the -V direction side.

[0039] As shown generally in Figures 2 to 5, the torque detector 10 includes a rotating shaft 12, a flange 13, and casings 14a to 14e. The torque detector 10 also includes a strain-generating portion 12c provided on the rotating shaft 12, and strain-sensitive resistors 1a and 1b (not shown in Figures 2 to 5, see Figures 6 and 7) attached to the strain-generating portion 12c. The torque detector 10 also includes elements including a motor portion, a rotating substrate 26, fixed substrates 28a and 28b, a primary core 21 and a secondary core 23, a rotary encoder 30, etc.

[0040] The rotating shaft 12 is the output shaft of the motor, and is a generally cylindrical metal member whose diameter changes stepwise in the axial direction (V direction). The rotating shaft 12 protrudes from a flange 13 so that it can be connected to a load device. As described later, the rotating shaft 12 has a strain-generating portion 12c, and strain-sensitive resistors 1a and 1b are attached to the strain-generating portion 12c.

[0041] The flange 13 is provided with a hole through which the rotating shaft 12 passes. The flange 13 also has holes for fixing the torque detector 10 to a device or the like. The flange 13 protects a rotating substrate 26, on which an electronic circuit for torque detection is mounted, and a member for supplying power to the rotating substrate 26 from the outside.

[0042] The casing 14a is connected to the flange 13 and holds a bearing 15a that supports the rotating shaft 12. The casing 14b is connected to the casing 14a and has a heat sink that radiates heat generated by the motor to the outside. The casing 14c is connected to the casing 14b and holds a bearing 15b that supports the rotating shaft 12. The casing 14d is connected to the casing 14c and protects the rotary encoder 30 that detects the rotational position of the rotating shaft 12 from the outside. The casing 14e protects the fixed board 28b, which has circuits mounted thereon that process the signals transmitted from the rotating board 26 and the rotary encoder 30, from the outside.

[0043] The flange 13 and the casings 14a to 14e protect the rotating substrate 26, on which an electronic circuit for torque detection is mounted, the fixed substrates 28a and 28b, the rotary encoder 30, the motor section, etc. from the outside. The rotating shaft 12 is rotatably supported by the bearings 15a and 15b.

[0044] Here, the above-mentioned bearings 15a and 15b are, for example, ball bearings. The bearing 15a is disposed with its outer ring fitted into the casing 14a. The bearing 15a is inserted into the rotating shaft 12 with its inner ring fitted, for example, by an interference fit, and the axial direction is restricted. The bearing 15b is disposed with its outer ring fitted into the casing 14c, and the axial direction is restricted by a partition member 19. The bearing 15b is inserted into the rotating shaft 12 with its inner ring fitted, for example, by an interference fit, and the axial direction is restricted. Note that the restrictions on the type, arrangement, and position of the bearings are merely examples and are not limited thereto.

[0045] <Internal configuration of torque detector 10> The internal configuration of the torque detector 10 will be described. The strain-flexing part 12c is provided on a part of the rotating shaft 12. For example, the strain-flexing part 12c is parallel to a plane including the axis of the rotating shaft 12 and has a shape obtained by cutting the rotating shaft 12 at a plurality of planes that are rotationally symmetric about the axis of the rotating shaft 12. The strain-flexing part 12c has strength in the axial direction of the rotating shaft 12 and does not deform, but by making the cross-sectional area smaller than that of the parts other than the strain-flexing part 12c, it is elastically deformed by the torsional torque generated in the rotating shaft 12.

[0046] In this embodiment, the strain-generating part 12c has two parallel flat parts (plural flat parts) facing each other. The boundary between the flat parts and the cylindrical shape has a shape in which the cross-sectional area of ​​the plane perpendicular to the rotation axis 12 gradually changes. In this embodiment, the strain-sensitive resistors 1a and 1b are attached to the two flat parts, respectively. As shown in Fig. 5, the axial length (V direction) of the flat parts to which the strain-sensitive resistors 1a and 1b are attached is approximately the same as the vertical length (Y direction in Fig. 1) of the strain-sensitive resistors 1a and 1b.

[0047] Here, the strain-sensitive resistors 1a and 1b attached to the strain-flexing portion 12c are incorporated into a Wheatstone bridge circuit that converts the detected strain into an electrical signal. The configuration of the strain-sensitive resistors 1a and 1b attached to the strain-flexing portion 12c and the Wheatstone bridge circuit will be described later.

[0048] The rotating substrate 26 is an annular disk, and is fixed to the rotating shaft 12 via a fixing member such as a collar, and rotates together with the rotating shaft 12. In this embodiment, the rotating substrate 26 is fixed to the load side of the rotor of the rotating shaft 12. The rotating substrate 26 includes a part of the resistance change detection circuit, an A / D converter, a CPU, and other rectifier circuits and stabilization circuits. The resistance change detection circuit includes a Wheatstone bridge circuit that detects the resistance change of the strain sensitive resistors 1a and 1b, and an amplifier. The A / D converter converts the output of the resistance change detection circuit into a digital signal. The CPU processes this digital signal to obtain the measured value of the torsional torque. The digital signal of the measured value of the torsional torque is then converted into an optical signal by the transmitting element 27 mounted on the rotating substrate 26, and is sent to a receiving element (not shown) mounted on the fixed substrate 28a by wireless communication.

[0049] The fixed boards 28a and 28b are mechanically and electrically connected by, for example, an inter-board connector, and the fixed board 28b is fixed to the casing 14e or the like. The fixed boards 28a and 28b are provided with a light receiving element and a digital demodulation circuit. The light receiving element is a photodiode or the like that converts the optical signal transmitted by the transmitting element 27 into an electric signal. The digital demodulation circuit extracts a signal of the measured value of the torsion torque from the digitally modulated signal that has been converted into an electric signal by the light receiving element, by digital demodulation. The fixed boards 28b are connected to a control device (not shown) that controls the torque detector 10 by a wiring cable. In addition, the fixed boards 28a and 28b are provided with a switching circuit or the like that is connected to an external control device (not shown).

[0050] The secondary core 23 is fixed to the outer circumferential surface of a hollow cylindrical member on the opposite load side of the position of the rotating shaft 12 where the rotating base plate 26 is fixed. The secondary core 23 is, for example, a magnetic sheet such as a ferrite sheet. A conductive wire such as a copper wire is wound around the outer circumferential cylindrical surface of the secondary core 23 to form a secondary coil 24.

[0051] The primary core 21 is fixed to the fixed substrate 28a at a position facing the secondary core 23 and the secondary coil 24, with the primary core holder 20 in between. The primary core 21 has a columnar shape with a U-shaped protrusion in cross section, and is made of a magnetic material such as ferrite. The primary coil 22 is a conductive wire such as a copper wire, and is wound around the two protrusions of the primary core 21, with its ends connected to the fixed substrate 28a.

[0052] In addition, a switching circuit of the fixed substrate 28a and the fixed substrate 28b connected to an external control device (not shown) converts the DC current supplied from the control device into an AC current. This switching circuit is connected to the primary coil 22 and outputs the converted AC current to the primary coil 22. However, when the AC current is supplied by the control device, the switching circuit is not required. The converted AC current generates an AC magnetic field in the primary coil 22 and induces a current in the secondary coil 24. Therefore, the secondary coil 24 can receive power from the primary coil 22 in a non-contact manner. The AC current induced in the secondary coil 24 is converted into a DC voltage by a rectifier circuit and a stabilization circuit in the rotating substrate 26, and the DC voltage is supplied to a resistance change detection circuit, an A / D converter, a CPU, etc.

[0053] The rotary encoder 30 is connected to the end of the rotating shaft 12 on the opposite load side, and detects the rotational position of the rotating shaft 12. In this embodiment, the rotary encoder 30 is of a reflective optical type, but it may be of a transmissive type, or may be of a magnetic or other type, not limited to an optical type. Power is supplied to the rotary encoder 30 and a position signal is output from the rotary encoder 30 via a cable with a connector (not shown) connected to the fixed substrate 28b, and the position signal is sent to an external control device.

[0054] The motor section is provided on the +V side of the axial direction of the rotating shaft 12. The motor section is, for example, an AC servo motor, and includes a stator 16 and a permanent magnet 17. The stator 16 is composed of a laminated core and a winding coil surrounding the laminated core. The stator 16 is fixed to the casing 14b.

[0055] A rotor is disposed at a predetermined interval inside the stator 16. The rotor is configured by attaching permanent magnets 17 to the rotating shaft 12. Here, the rotor may be a surface magnet type (SPM) in which the permanent magnets are bonded to the surface of a support member, or an interior magnet type (IPM) in which the support member is expanded in the radial direction and the permanent magnets are embedded inside the support member.

[0056] <Configuration of strain-sensitive resistors 1a and 1b> The strain-sensitive resistors 1a and 1b are configured similarly to the strain-sensitive resistor 1 shown in Fig. 1 and are attached to the flat surface of the strain-sensitive portion 12c. Fig. 6 shows a cross-sectional view of the strain-sensitive portion 12c cut along a plane perpendicular to the axial direction of the rotating shaft 12. As shown generally in Figs. 5 and 6, the strain-sensitive resistor 1a is attached to the VW flat portion on the +U direction side of the strain-sensitive portion 12c, and the strain-sensitive resistor 1b is attached to the VW flat portion on the -U direction side. In this embodiment, as described above, the length of the V direction side of the flat portion of the strain-sensitive portion 12c is approximately the same as the length of the strain-sensitive resistors 1a and 1b on the Y direction side (see Fig. 1).

[0057] The strain sensitive resistors 1a and 1b are configured similarly to the strain sensitive resistor 1 shown in Fig. 1. In this embodiment, the sensitive elements of the strain sensitive resistor 1a corresponding to the sensitive elements 3A and 3B are denoted as sensitive elements 3aA and 3aB, respectively, and the sensitive elements of the strain sensitive resistor 1b corresponding to the sensitive elements 3A and 3B are denoted as sensitive elements 3bA and 3bB, respectively.

[0058] The strain-sensitive resistors 1a and 1b detect the strain generated in the strain-generating part 12c in response to the torsional torque applied to the rotating shaft 12. The strain-sensitive resistors 1a and 1b are incorporated into a Wheatstone bridge circuit that converts the detected strain into an electrical signal. The circuit is mounted on a rotating substrate 26.

[0059] <Configuration of a Wheatstone bridge circuit including strain sensitive resistors 1a and 1b> The configuration of a Wheatstone bridge circuit including the strain sensitive resistors 1a and 1b will be described. Fig. 7 shows the configuration of a Wheatstone bridge circuit including the strain sensitive resistors 1a and 1b of a torque detector 10 and peripheral circuits. As shown in Fig. 7, in addition to the Wheatstone bridge circuit, an amplifier circuit 51, an analog / digital conversion circuit 52, and a display device 53 are provided.

[0060] In the Wheatstone bridge circuit, the terminal 6c of the strain sensitive resistor 1a having the sensitive elements 3aA and 3aB is connected to the terminal T1, and the terminal 6c of the strain sensitive resistor 1b having the sensitive elements 3bA and 3bB is connected to the terminal T3. The terminal 6a of the strain sensitive resistor 1a is connected to the terminal T4, and the terminal 6b of the strain sensitive resistor 1a is connected to the terminal T2. The terminal 6a of the strain sensitive resistor 1b is connected to the terminal T2, and the terminal 6b of the strain sensitive resistor 1b is connected to the terminal T4.

[0061] The amplifier circuit 51 amplifies an analog signal output from a Wheatstone bridge circuit including the strain sensitive resistors 1a and 1b. The analog / digital conversion circuit 52 converts the analog signal into a digital signal. The display device 53 includes a display device such as a liquid crystal panel, and a display control circuit that displays information on the display device based on the signal sent from the analog / digital conversion circuit 52. The display device 53 displays information related to the detected torsion moment of the rotating shaft 12.

[0062] [State of strain-generating portion 12c and strain-sensitive resistors 1a, 1b when rotating shaft 12 is twisted] Fig. 8 is a planar development of the approximately rectangular parallelepiped strain-flexing part 12c to which the strain-sensitive resistors 1a and 1b are attached. Fig. 9 is a conceptual diagram for explaining the state of the surface of the strain-flexing part 12c to which the strain-sensitive resistors 1a and 1b are attached when the rotating shaft 12 is twisted in the illustrated direction τ. As shown in Fig. 9, when the rotating shaft 12 is twisted in the illustrated direction τ, the surface of the strain-flexing part 12c expands in a diagonal direction not connecting points D and E, and contracts in a diagonal direction connecting points F and G. Here, [T] indicates that the surface of the strain-flexing part 12c expands, and [C] indicates that the surface of the strain-flexing part 12c contracts.

[0063] 8, when the rotating shaft 12 is twisted in the direction τ and the strain generating part 12c is deformed, in accordance with the deformation, in the strain-sensitive resistor 1a, the resistors constituting the sensing element 3aA shrink and the resistors constituting the sensing element 3aB expand. In addition, in the strain-sensitive resistor 1b, the resistors constituting the sensing element 3bA shrink and the resistors constituting the sensing element 3bB expand.

[0064] In this way, when the rotating shaft 12 is twisted in the direction τ and the strain-flexing part 12c of the sensing elements 3aA and 3bA is deformed, the multiple resistors constituting these elements expand. Also, when the rotating shaft 12 is twisted in the direction τ and the strain-flexing part 12c of the sensing elements 3aB and 3bB is deformed, the multiple resistors constituting these elements contract.

[0065] In this manner, in the torque detector 10 according to this embodiment, the axial length of the strain-flexible part 12c provided on the rotating shaft 12 is approximately the same as the longitudinal length (Y direction in FIG. 1) of the strain-sensitive resistors 1a and 1b. This makes it possible to shorten the axial length of the strain-flexible part 12c to which the strain-sensitive resistors 1a and 1b are attached, thereby improving the rigidity of the rotating shaft 12.

[0066] As described above, in this embodiment, since the strain-sensitive resistor 1 (1a, 1b) has the configuration as shown in Fig. 1, soldering of lead wires to the terminals 6a to 6c is easy. In addition, since the strain-sensitive resistor 1 (1a, 1b) has the configuration as shown in Fig. 1, when soldering of lead wires to the terminals 6a to 6c, the lead wires can be drawn out either in the +Y direction or in the -Y direction.

[0067] In this embodiment, the strain-sensitive resistor 1 (1a, 1b) has the sensitive elements 3A, 3B and the terminals 6a to 6c arranged in a row in the X direction, so that the length in the Y direction is short. This makes it possible to shorten the axial length of the strain-generating part 12c of the rotating shaft 12 in the torque detector 10, and improve the rigidity of the rotating shaft 12.

[0068] Therefore, according to this embodiment, a new strain-sensitive resistor 1 (1a, 1b) can be obtained that is easy to solder, etc. Also, according to this embodiment, the degree of rigidity of the rotating shaft 12 of the torque detector 10 can be improved by using the strain-sensitive resistor 1 (1a, 1b).

[0069] [Modifications of the embodiment] The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0070] In this embodiment, the strain-sensitive resistor of this embodiment is used in a torque detector, but the strain-sensitive resistor can also be used in a force detector such as a load cell in which measurement is performed by shear strain deformation.

[0071] In the above embodiment, the strain-flexing part is rectangular and the biaxial shear-type strain-sensitive resistors are attached to two planes parallel to the rotation axis of the torque detector. Alternatively, the biaxial shear-type strain-sensitive resistors may be attached to four planes. The shape of the strain-flexing part may be another shape, such as a hexagonal prism.

[0072] Further, although the torque detector of the present embodiment does not include a wave reducer, it may include a wave reducer.

[0073] In addition, in the above embodiment, the torsional moment of the shaft is detected using a strain-sensitive resistor, but other quantities such as load may also be detected as long as the force applied to the strain-sensitive resistor is detected. [Industrial Applicability]

[0074] As described above, the strain sensitive resistor of the present embodiment can be applied to a strain sensitive resistor of a torque detector. Also, the torque detector of the present invention can be applied to a torque detector that detects torque. [Explanation of symbols]

[0075] 1,1a,1b: Strain-sensitive resistor 2: Base material 3A: Sensing element (first sensing element) 3B: Sensing element (second sensing element) 3aA, 3aB, 3bA, 3bB: sensing elements 5a, 5b, 5c: Wiring section 6a: Terminal portion (first terminal portion) 6b: Terminal portion (second terminal portion) 6c: Terminal part (third terminal part) 7:Protective layer 10: Torque detector 12: Rotation axis 12c: Strain part 13: Flange 14a~14e: Casing 15a, 15b: Bearings 16: Stator 17: Permanent magnet 19: Partition material 20: Primary core holder 21: Primary core 22: Primary coil 23: Secondary core 24: Secondary coil 26: Rotating substrate 27: Transmitting element 28a, 28b: Fixed board 30: Rotary encoder 51: Amplification circuit 52: Analog / digital conversion circuit 53:Display device T1, T2, T3, T4: Terminals

Claims

1. A torque detector that includes a strain-generating part and a strain-sensitive resistor and detects a torsional torque of a rotating shaft of a motor part, The strain-generating portion is The torsional torque acts on the rotating shaft to elastically deform the thin-walled portion of the rotating shaft in the axial direction. The strain sensitive resistor is The substrate has two sensor elements having a folded pattern for detecting strain formed by a resistor, and three terminal portions each extending from the sensor elements by wiring, the terminal portions being provided as regions on the same surface extending along the axial direction of the rotation shaft with a predetermined width, The substrate is attached to the exposed flat surface of the thin-walled portion at the strain-flexing portion, The sensing element and the terminal portion provided as each of the regions are A step extending in the middle of the inner side from the edge of the base material with the predetermined width is a part related to a configuration of a step arrangement in which a plurality of steps are adjacent to each other as a half region along a direction perpendicular to the axial direction, In addition, the regions related to the configuration of the staged arrangement correspond to the half regions that alternate so as to arrange the sensing elements in parallel between the terminal parts, One or the other of the three half regions that are to be the terminal portions in the axial direction is A plus side region that extends from one side end of the half region to one edge of the base material along the extension of the predetermined width without the folded pattern of the sensing element being arranged; Or a minus side region extending from the other side end of the half region to the other edge of the substrate along the extension of the predetermined width without the folded pattern of the sensing element being arranged; and a torque detector having the same on the same plane.

2. A force detector including a strain-generating part and a strain-sensitive resistor, the force detector detecting a force applied to the strain-generating part, The strain-generating portion is The elastic body is provided in a thin-walled portion where elastic deformation occurs due to a shear action caused by the application of force, The strain sensitive resistor is The substrate has two sensory elements having a folded pattern for detecting strain formed by a resistor, and three terminal portions each extending from the sensory elements by wiring, each extending in a predetermined width along a second direction perpendicular to a first direction in which the shear occurs in a virtual plan view of the strain generating portion, and the substrate has a base material in which the two sensory elements have a folded pattern for detecting strain formed by a resistor, and three terminal portions each extending in a predetermined width along a second direction perpendicular to a first direction in which the shear occurs in a virtual plan view of the strain generating portion; The substrate is attached to the exposed flat surface of the thin-walled portion at the strain-flexing portion, The sensing element and the terminal portion provided as each of the regions are A step extending in the middle of the base material from the edge of the base material to the predetermined width is a part related to a step arrangement configuration in which a plurality of steps are adjacent to each other as a half region along the first direction, In addition, the regions related to the configuration of the staged arrangement correspond to the half regions that alternate so as to arrange the sensing elements in parallel between the terminal parts, One or the other of the three half regions that are the terminal portions toward the second direction is A plus side region that extends from one side end of the half region to one edge of the base material along the extension of the predetermined width without the folded pattern of the sensing element being arranged; Or a minus side region extending from the other side end of the half region to the other edge of the substrate along the extension of the predetermined width without the folded pattern of the sensing element being arranged; and a force detector having on said same plane.

Images