Torque sensor

Abstract

To provide a torque sensor in which a circuit board is provided at a position where the whole of the torque sensor can easily be downsized.SOLUTION: A torque sensor 10 comprises: a first structure 11 which is formed in annular form; a second structure 12 which is formed in annular form on the inner circumferential side of the first structure 11; a plurality of third structures 13 for connecting the first structure 11 and the second structure 12; a sensor unit 14 which is provided between the first structure 11 and the second structure 12; and a circuit board 15 which is accommodated in a groove 111 formed on an outer circumferential side surface or an inner circumferential side surface of the first structure 11 or the second structure 12, for detecting torque on the basis of strains detected by the sensor unit 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a torque sensor that detects torque.

Background Art

[0002] There is known a torque sensor that detects torque by a strain sensor provided between a first structure and a second structure that are concentrically arranged in a ring shape and provided between the first structure located on the outside and the second structure located on the inside. Further, in such a torque sensor, it is disclosed that a case is provided in a space at the center of the inner second structure, and a processing circuit is provided inside this case (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, depending on the position where the circuit board for detecting torque is provided, it becomes difficult to miniaturize the entire torque sensor. An object of the present embodiment is to provide a torque sensor in which a circuit board is provided at a position where the entire torque sensor can be easily miniaturized.

Effects of the Invention

[0005] According to the present embodiment, it is possible to provide a torque sensor in which a circuit board is provided at a position where the entire torque sensor can be easily miniaturized.

Means for Solving the Problems

[0006] The torque sensor according to an embodiment of the present invention includes a first structure formed in an annular shape, a second structure formed in an annular shape on the inner peripheral side of the first structure, a plurality of third structures connecting the first structure and the second structure, a sensor unit provided between the first structure and the second structure, and a circuit board housed in a groove formed on a side surface of an outer periphery or an inner periphery of the first structure or the second structure, and detecting torque based on the strain detected by the sensor unit.

Brief Description of the Drawings

[0007]

Figure 1

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Embodiments for Carrying Out the Invention

[0008] (First Embodiment) FIG. 1 is a configuration diagram simply showing the configuration of the torque sensor 10 according to the first embodiment. FIG. 2 is a cross-sectional view of the first structure 11 according to the present embodiment taken along the line A-A of FIG. 1. In the drawings, the same parts are denoted by the same reference numerals.

[0009] The torque sensor 10 is a sensor that detects the torque Mz. The torque Mz is the moment about the z-axis (rotation axis direction) shown in FIG. 1. Here, the x-axis, y-axis, and z-axis are orthogonal to each other. Note that the torque sensor 1 may be a sensor with another name such as a force sensor as long as it can detect at least the torque Mz.

[0010] The torque sensor 10 includes a first structure 11, a second structure 12, a plurality of third structures 13, a plurality of sensor units 14, and a circuit board 15.

[0011] The first structure 11, the second structure 12, and the third structure 13 are integrally formed as one elastic body. The first structure 11, the second structure 12, and the third structure 13 are made of a metal such as stainless steel, but a material other than metal (such as resin) may be used as long as it has sufficient mechanical strength against forces such as the applied torque Mz.

[0012] The first structure 11 and the second structure 12 are formed in an annular shape. The diameter of the second structure 12 is smaller than the diameter of the first structure 11. The second structure 12 is arranged on the inner peripheral side concentrically with the first structure 11.

[0013] On the side surface of the outer periphery of the first structure 11, at least one groove 111 for accommodating at least one circuit board 15 is formed. The groove 111 is formed between the thickness directions of the first structure 11 along the outer periphery of the first structure 11. The groove 111 may be connected in one piece so as to go around the outer periphery of the first structure 11, or a plurality of grooves 111 may be formed so that each of the plurality of circuit boards 15 can be accommodated. When there is one groove 111, the circuit boards 15 may also be connected in one piece, or a plurality of circuit boards 15 may be accommodated in one groove 111. On the inner peripheral side of the first structure 11, a cavity 112 for accommodating wirings and the like connected to the circuit board 15 is provided. The cavity 112 is preferably formed at a position adjacent to the groove 111 from the viewpoint of ease of wiring and the like. Note that the cavity 112 may not be provided.

[0014] The groove 111 and the circuit board 15 can be of any number and any shape. In FIG. 1, two grooves 111 having a length of about half of the outer periphery of the first structure 11 are provided symmetrically, and the circuit board 15 accommodated in the groove 111 has an arc-shaped flat plate shape with a length of about half of the circle of the outer periphery of the first structure 11.

[0015] The plurality of third structures 13 are arranged radially and provided as beams connecting the first structure 11 and the second structure 12. For example, eight third structures 13 are provided at equal intervals (at 45-degree intervals) in the circumferential direction. Note that any number of third structures 13 may be provided. For example, the third structures 13 are provided in the same number as the sensor units 14 so as to correspond to each of the plurality of sensor units 14.

[0016] The sensor unit 14 is provided so as to straddle between the first structure 11 and the second structure 12. For example, the sensor unit 14 is provided on the third structure 13, but may be provided at a location other than the third structure 13. Here, the sensor unit 14 is provided on each of the third structures 13 and eight sensor units 14 are provided at equal intervals (at 45-degree intervals) in the circumferential direction, but the present invention is not limited to this. Any number of sensor units 14 may be provided, and the number of sensor units 14 does not have to be the same as the number of third structures 13. For example, an even number of sensor units 14, such as two, four, six, or eight, may be provided.

[0017] The sensor unit 14 detects the strain generated by the relative movement of the first structure 11 and the second structure 12. For example, the sensor unit 14 is configured such that a sensor element such as a strain gauge is provided on the surface of the strain generating body where strain occurs. The sensor element constitutes an electric circuit such as a full bridge circuit or a bridge circuit. The data indicating the strain detected by the sensor unit 14 is transmitted to the circuit board 15 as an electric signal. For example, the sensor unit 14 is electrically connected to the circuit board 15 by wiring such as a flexible printed circuit board.

[0018] The circuit board 15 receives, as an electric signal, the strain detected by the sensor unit 14 from the sensor unit 14. The circuit board 15 is a board on which an electric circuit for detecting the applied torque Mz is configured based on the strain detected by the sensor unit 14. For example, the circuit board 15 is a printed circuit board (PCB). The circuit board 15 is installed inside the groove 111. All the sensor units 14 are connected to at least one circuit board 15. The wiring connected to the sensor unit 14 may be housed in the cavity 112 formed in the first structure 11.

[0019] Each sensor unit 14 may be connected to any circuit board 15. It is desirable that the number of sensor units 14 connected to each circuit board 15 be determined to be equal. Also, it is desirable that each sensor unit 14 be connected to the nearest circuit board 15. When a plurality of circuit boards 15 are located at the same distance from one sensor unit 14, the circuit board 15 connected to that sensor unit 14 may be determined in any manner.

[0020] For example, in FIG. 1, the sensor unit 14 connected to the two circuit boards 15 is determined as follows. The torque sensor 10 is divided into two halves such that the two circuit boards 15 are symmetrically positioned left and right. The three sensor units 14 on the left half are connected to the circuit board 15 on the left side. The three sensor units 14 on the right half are connected to the circuit board 15 on the right side. The two sensor units 14 on the line dividing them in half are connected to separate circuit boards 15 so as to be evenly connected to the two circuit boards 15. For example, the upper sensor unit 14 is connected to the circuit board 15 on the left side, and the lower sensor unit 14 is connected to the circuit board 15 on the right side.

[0021] According to the present embodiment, by forming the groove 111 on the side surface of the outer periphery of the first structure 11 and arranging the circuit board 15 connected to the sensor unit 14 to be housed in the groove 111, the overall size of the torque sensor 10 can be reduced.

[0022] For example, when the circuit board 15 is provided in the circular space at the center of the annular second structure 12, this space must ensure a certain size for providing the circuit board 15. If this space is enlarged (if the outer circle of the space is enlarged), the outer shape of the second structure 12 becomes larger, and further, the outer shape of the first structure 11 also becomes larger. In contrast, in the present embodiment, since the space at the center of the second structure 12 may not be provided, this space can be made infinitely small. Therefore, by reducing the first structure 11 and the second structure 12, the torque sensor 10 can be made smaller as a whole.

[0023] In the present embodiment, the groove 111 is formed on the side surface of the outer periphery of the first structure 11, but the groove 111 may be formed on the side surface of the outer periphery of the second structure 12. In this case, similar to the groove 111A of the second embodiment described later, the groove 111 may be provided so as to avoid the connection portion of the second structure 12 with the third structure 13. For example, the groove 111 may be formed between two adjacent third structures 13. Even when the groove 111 is formed on the outer periphery of the second structure 12, the same operational effects as those of the present embodiment can be obtained.

[0024] (Second Embodiment) FIG. 3 is a configuration diagram simply showing the configuration of the torque sensor 10A according to the second embodiment. FIG. 4 is a cross-sectional view of the first structure 11A according to the present embodiment taken along line B-B in FIG. 3.

[0025] The torque sensor 10A has a configuration in which a groove 111A for housing the circuit board 15 is formed on the inner peripheral side surface of the first structure 11A. Other points are basically the same as those of the torque sensor 10 according to the first embodiment. Here, mainly, the points different from the first embodiment will be described.

[0026] Four third structures 13 are provided at equal intervals (90-degree intervals) in the circumferential direction. The sensor unit 14 is provided on each of the third structures 13. Note that, similar to the first embodiment, any number of third structures 13 may be provided. Also, the sensor unit 14 may be provided at a location other than the third structure 13, and any number of sensor units 14 may be provided.

[0027] At least one groove 111A for housing at least one circuit board 15 is formed on the inner peripheral side surface of the first structure 11A. The groove 111A is formed between the thickness directions of the first structure 11A along the inner periphery of the first structure 11A. Each groove 111A is formed on the inner peripheral side surface of the first structure 11A located between two adjacent third structures 13. That is, the groove 111A is formed so as to avoid the connection portion of the third structure 13. For example, as shown in FIG. 3, the groove 111A is formed on the inner periphery of the first structure 11A so as not to overlap with the connection portion of the third structure 13.

[0028] Note that any number of grooves 111A may be provided, or they may be connected into one so as to go around the inner periphery of the first structure 11A. Also, the groove 111A may be provided at a position overlapping with the connection portion of the third structure 13 on the inner periphery of the first structure 11A. For example, the groove 111A may be formed above or below the connection portion of the third structure 13 on the inner peripheral side surface of the first structure 11A.

[0029] On the outer peripheral side of the first structure 11A, similar to the cavity 112 according to the first embodiment, a cavity 112A for accommodating wirings and the like connected to the circuit board 15 is provided. Note that the cavity 112A may not be provided.

[0030] Similar to the first embodiment, the groove 111A and the circuit board 15 can have any number and any shape. For example, as shown in FIG. 3, grooves 111A are formed between all adjacent pairs of the third structures 13. As a result, four grooves 111A are formed. Four circuit boards 15 are provided so as to be accommodated in each groove 111A. The circuit board 15 is formed in a shape that can be accommodated in the groove 111A. When four grooves 111A are provided, the shape of the groove 111A is smaller than the shape obtained by circumferentially dividing the annular first structure 11A into four parts. The circuit board 15 is formed in a shape even smaller than the shape of the groove 111A. For example, the groove 111A forms an arc-shaped space shorter than one-fourth of the inner circumference of the first structure 11, and the circuit board 15 has an arc-shaped flat plate shape that can be accommodated in this space of the groove 111A.

[0031] Similar to the first embodiment, each sensor unit 14 may be connected to any circuit board 15. For example, each sensor unit 14 is connected to the nearest circuit board 15. In the case of the torque sensor 10A shown in FIG. 3, the four sensor units 14 and the four circuit boards 15 are connected in a one-to-one correspondence.

[0032] According to the present embodiment, by forming the groove 111A on the inner peripheral side surface of the first structure 11A and arranging the circuit board 15 connected to the sensor unit 14 to be accommodated in the groove 111A, the torque sensor 10A can be made smaller as a whole, similar to the first embodiment.

[0033] In the torque sensor 10A, the groove 111A is formed on the inner peripheral side surface of the first structure 11A, but the groove 111A may be formed on the inner peripheral side surface of the second structure 12. Also in this case, the same operational effects as those of the present embodiment can be obtained.

[0034] (Third Embodiment) FIG. 5 is a configuration diagram simply showing the configuration of the torque sensor 10B according to the third embodiment. FIG. 6 is a cross-sectional view of the first structure 11B according to this embodiment cut along the line C-C of FIG. 5.

[0035] The torque sensor 10B has a configuration in which grooves 111a and 111b for housing the circuit boards 15a and 15b are formed on the outer peripheral side surface and the inner peripheral side surface of the first structure 11B, respectively.

[0036] The groove 111a formed on the outer peripheral side surface of the first structure 11B and the circuit board 15a provided in this groove 111a are the same as the groove 111 and the circuit board 15 according to the first embodiment.

[0037] The groove 111b formed on the inner peripheral side surface of the first structure 11B and the circuit board 15b provided in this groove 111b are the same as the groove 111A and the circuit board 15 according to the second embodiment.

[0038] Other points are basically the same as those in the first embodiment or the second embodiment. Here, mainly, the points different from the first embodiment and the second embodiment will be described.

[0039] The outer peripheral side circuit board 15a and the inner peripheral side circuit board 15b may correspond to the circuit board 15 according to the first embodiment when the two are combined, or each may correspond to the circuit board 15 according to the first embodiment. Further, the outer peripheral side circuit board 15a and the inner peripheral side circuit board 15b may be electrically or circuitously connected.

[0040] Either one of the outer peripheral side groove 111a and the inner peripheral side groove 111b may not be provided with the circuit boards 15a and 15b, or instead of the circuit boards 15a and 15b, wirings or the like may be housed.

[0041] Similar to the first or second embodiment, each sensor unit 14 may be connected to any of the circuit boards 15a and 15b. For example, each sensor unit 14 is connected to the nearest circuit boards 15a and 15b. One sensor unit 14 may be connected to one circuit board 15a or 15b, or one sensor unit 14 may be connected to each of the outer peripheral circuit board 15a and the inner peripheral circuit board 15b.

[0042] According to the present embodiment, by forming grooves 111a and 111b on the outer peripheral side surface and the inner peripheral side surface of the first structure 11B respectively, and arranging the circuit boards 15a and 15b to be respectively accommodated in the grooves 111a and 111b, the same operational effects as those of the first or second embodiment can be obtained.

[0043] In the present embodiment, the grooves 111a and 111b are respectively formed on the outer peripheral side surface and the inner peripheral side surface of the first structure 11B. However, the grooves 111a and 111b may be respectively formed on the outer peripheral side surface and the inner peripheral side surface of the second structure 12. Also in this case, the same operational effects as those of the present embodiment can be obtained.

[0044] (Fourth Embodiment) FIG. 7 is a configuration diagram simply showing the configuration of the torque sensor 10C according to the fourth embodiment. FIG. 8 is a perspective view showing a part of the configuration by the first structure 11C, the second structure 12C, and the third structure 13C according to the present embodiment. FIG. 9 is a cross-sectional view of the torque sensor 10C according to the present embodiment cut along the line D-D of FIG. 7.

[0045] The torque sensor 10C is basically the same as the torque sensors 10, 10A, and 10B according to the first to third embodiments. Here, mainly, the differences from the first to third embodiments will be described.

[0046] FIG. 8 shows a configuration in which a portion including the third structure 13C of the torque sensor 10C shown in FIG. 7 is cut away. As shown in FIG. 8, in the torque sensor 10C, the first structure 11C and the second structure 12C are provided with a step. The third structure 13C is provided so as to connect the stepped first structure 11C and the second structure 12C.

[0047] As shown in FIG. 7, the sensor unit 14 may be provided in a portion other than the third structure 13C, or may be provided in the third structure 13C.

[0048] The groove 111Ca for accommodating the circuit board 15Ca is formed on the outer peripheral side surface of the first structure 11C. The groove 111Cb for accommodating the circuit board 15Cb is formed on the inner peripheral side surface of the second structure 12C. The grooves 111Ca and 111Cb are the same as the grooves 111a and 111b according to the third embodiment, respectively. The circuit boards 15Ca and 15Cb are the same as the circuit boards 15a and 15b according to the third embodiment, respectively.

[0049] According to the present embodiment, in the torque sensor 10C having a step between the first structure 11C and the second structure 12C, by forming the grooves 111Ca and 111Cb in the first structure 11C and the second structure 12C, respectively, and arranging the circuit boards 15Ca and 15Cb to be accommodated in the grooves 111Ca and 111Cb, respectively, the same operational effects as at least one of the first to third embodiments can be obtained.

[0050] In the present embodiment, the groove 111Ca is formed on the outer peripheral side surface of the first structure 11C, and the groove 111Cb is formed on the inner peripheral side surface of the second structure 12C. However, only one of the grooves 111Ca and 111Cb may be formed. Also, only one of the circuit boards 15Ca and 15Cb may be provided, which are respectively accommodated in the outer peripheral side groove 111Ca and the inner peripheral side groove 111Cb. Even in this case, the same operational effects as the present embodiment can be obtained.

[0051] Additional advantages and modifications will readily occur to those skilled in the art. Accordingly, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Explanation of Signs

[0052] 10…Torque sensor, 11…First structure, 12…Second structure, 13…Third structure, 14…Sensor unit, 15…Circuit board, 111…Groove, 112…Cavity.

Claims

1. a first structure formed in a ring shape; a second structure formed in a ring shape on the inner peripheral side of the first structure; a plurality of third structures connecting the first structure and the second structure; a sensor unit provided between the first structure and the second structure; a circuit board that is housed in a groove formed on the outer peripheral side surface or the inner peripheral side surface of the first structure or the second structure, and detects torque based on the strain detected by the sensor unit A torque sensor characterized by comprising the above.

2. A wiring that is housed in a cavity formed in the first structure or the second structure and electrically connects the sensor unit and the circuit board The torque sensor according to claim 1, characterized by comprising the above.

3. The groove in which the circuit board is housed is formed between two adjacent third structures on the inner peripheral side surface of the first structure or the outer peripheral side surface of the second structure The torque sensor according to claim 1, characterized by the above.

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