Torque sensor

Abstract

A torque sensor comprises: a first magnetism collection member (41); a second magnetism collection member (42); magnetic sensors (33a, 33b); and a circuit board (34). The first magnetism collection member (41) has a first body (51), and first projections (52a, 52b). The second magnetism collection member (42) has a second body (61), and second projections (62a, 62b). The magnetic sensors (33a, 33b) are on the circuit board (34), and are arranged between the first projections (52a, 52b) and the second projections (62a, 62b). The circuit board (34) has recesses (103a, 103b) at positions corresponding to the magnetic sensors (33a, 33b). The magnetic sensors (33a, 33b) are at least partially arranged in the recesses (103a, 103b). The entirety of the first projections (52a, 52b) and the second projections (62a, 62b) is arranged outside the recesses (103a, 103b).

Description

Torque Sensor

[0001] The present disclosure relates to a torque sensor.

[0002] For example, Patent Document 1 discloses a torque sensor that detects torque applied to a rotating shaft. The rotating shaft includes an input shaft and an output shaft that is connected to the input shaft via a torsion bar.

[0003] The torque sensor disclosed in Patent Document 1 includes a permanent magnet that rotates integrally with the input shaft, a pair of yoke cores that rotate integrally with the output shaft, a pair of magnetic flux collector rings arranged on the outer peripheries of the pair of yoke cores, a magnetic sensor that generates a signal corresponding to magnetic flux, and a circuit board on which the magnetic sensor is mounted. Each magnetic flux collector ring has a ring portion and a protrusion that protrudes radially outward from the ring portion. The circuit board has a notch that penetrates in the thickness direction at a location corresponding to the magnetic sensor. The circuit board is assembled to the torque sensor so that the magnetic sensor is positioned between the protrusions of the pair of magnetic flux collector rings and the protrusion of one of the pair of magnetic flux collector rings is positioned within the notch.

[0004] Therefore, in the torque sensor of Patent Document 1, the protrusions of the pair of magnetic flux collecting rings can be arranged close to each other, and the gap between these protrusions can be reduced, which increases the amount of magnetic flux passing through the magnetic sensor, thereby improving the signal-to-noise ratio (SN ratio) of the signal output from the magnetic sensor.

[0005] Japanese Patent Application Laid-Open No. 2020-16608

[0006] In the torque sensor of Patent Document 1, for example, the dimensional tolerances and assembly tolerances of the magnetic flux collecting ring and the circuit board must be strictly controlled so that the protrusion does not interfere with the circuit board.

[0007] According to one aspect of the present disclosure, there is provided a torque sensor configured to detect torque applied to a rotating shaft. The rotating shaft includes a first shaft and a second shaft connected to the first shaft via a torsion bar. The torque sensor includes a permanent magnet configured to rotate integrally with the first shaft, a first yoke core and a second yoke core configured to rotate integrally with the second shaft, a first magnetic flux collector disposed at a distance from the first yoke core and a second magnetic flux collector disposed at a distance from the second yoke core, a magnetic sensor configured to generate a signal corresponding to magnetic flux flowing through the first magnetic flux collector and the second magnetic flux collector, and a circuit board on which the magnetic sensor is mounted. The first magnetic flux collector has a first main body portion facing the first yoke core and a first protrusion protruding from the first main body portion. The second magnetic flux collector has a second main body portion facing the second yoke core and a second protrusion protruding from the second main body portion and facing the first protrusion. The magnetic sensor is disposed on the circuit board between the first protrusion and the second protrusion. The circuit board has a recess at a position corresponding to the magnetic sensor. At least a portion of the magnetic sensor is disposed within the recess. The first protrusion and the second protrusion are each entirely disposed outside the recess.

[0008] Fig. 2 is an exploded perspective view of a torque sensor of a first embodiment. Fig. 3 is a partial cross-sectional view taken along the axial direction of the torque sensor of Fig. 1. Fig. 4 is a perspective view of a first magnetic flux collecting member, a second magnetic flux collecting member, and a circuit board constituting the torque sensor of Fig. 1, as viewed from below. Fig. 5 is an enlarged cross-sectional view taken along the axial direction of the vicinity of the magnetic sensor in the torque sensor of Fig. 1, and is a cross-sectional view taken along line IV-IV in Fig. 2. Fig. 6 is an enlarged cross-sectional view taken along the axial direction of the vicinity of the magnetic sensor in a torque sensor of a second embodiment.

[0009] First Embodiment A first embodiment of the torque sensor 1 will be described below with reference to the drawings. In this specification, the term "cylindrical" refers to a shape that can be considered cylindrical as a whole, and includes shapes formed by combining multiple components and shapes with a notch, such as a C-shape. The "cylindrical" shape includes, but is not limited to, a circle, an ellipse, and a polygon with sharp or rounded corners when viewed in the axial direction. The term "annular" refers to a shape that can be considered circular as a whole, and includes shapes formed by combining multiple components and shapes with a notch, such as a C-shape. The term "annular" refers to a shape that can be considered circular as a whole, and includes, but is not limited to, a circle, an ellipse, and a polygon with sharp or rounded corners when viewed in the axial direction. The term "facing" in this specification refers to surfaces or members facing each other, and includes not only cases where the surfaces or members face each other completely, but also cases where the surfaces or members face each other partially. In addition, in this specification, "facing" includes both a case where a member other than the two parts is interposed between the two parts, and a case where nothing is interposed between the two parts.

[0010] (Overall Configuration) As shown in FIGS. 1 and 2 , the torque sensor 1 is provided around a rotating shaft 2. The rotating shaft 2 is rotatably accommodated in a housing 3. The rotating shaft 2 includes an input shaft 4, which is a first shaft, a torsion bar 5, and an output shaft 6, which is a second shaft. The input shaft 4 and the output shaft 6 are connected to each other via the torsion bar 5. The input shaft 4, the torsion bar 5, and the output shaft 6 are located on the same axis L. For example, the rotating shaft 2 is a pinion shaft of a rack-and-pinion mechanism that constitutes a steering device of a vehicle, and the housing 3 is a gear housing that accommodates the rack-and-pinion mechanism. A steering wheel is connected to the upper end of the pinion shaft via an intermediate shaft and a column shaft. In other embodiments, the rotating shaft 2 may be a column shaft.

[0011] The torque sensor 1 includes a permanent magnet 11 that rotates integrally with the input shaft 4, a magnetic yoke assembly 12 that rotates integrally with the output shaft 6, and a fixed unit 13 that is fixed to the housing 3. When torque is applied to the rotating shaft 2 through the driver's operation of the steering wheel, the torsion bar 5 twists, causing the input shaft 4 and the output shaft 6 to rotate relative to each other. As a result, the relative circumferential positions of the permanent magnet 11 and the magnetic yoke assembly 12 change, and the magnetic flux passing through a first magnetic flux collecting member 41 and a second magnetic flux collecting member 42 of the fixed unit 13 (described later) changes. In other words, the magnetic flux passing through the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42 changes depending on the magnitude of the torque input by the driver. The torque sensor 1 detects the torque applied to the rotating shaft 2 based on this change in magnetic flux. Each component of the torque sensor 1 will be described in detail below.

[0012] 1, the permanent magnet 11 is a cylindrical ring magnet. In this embodiment, the permanent magnet 11 has a circular shape when viewed in the axial direction.

[0013] The permanent magnet 11 is magnetized in the radial direction of the permanent magnet 11 so that magnetic poles of different polarities are arranged alternately in the circumferential direction. The permanent magnet 11 is fixed to the outer circumferential surface of the input shaft 4 directly or via a holder (not shown) so as to be rotatable together with the outer circumferential surface of the input shaft 4. In another embodiment, the permanent magnet 11 may be a plurality of plate-shaped magnets.

[0014] (Magnetic yoke assembly 12) The magnetic yoke assembly 12 includes a first yoke core 21, a second yoke core 22, and a yoke holder 23 that holds the first yoke core 21 and the second yoke core 22. The magnetic yoke assembly 12 is disposed on the outer periphery of the permanent magnet 11 with a gap therebetween. The magnetic yoke assembly 12 is fixed to the outer periphery of the output shaft 6 via a holder (not shown) or directly so as to be rotatable integrally therewith.

[0015] Each of the first yoke core 21 and the second yoke core 22 is made of a magnetic material and has an annular shape. In this embodiment, each of the first yoke core 21 and the second yoke core 22 has a circular shape when viewed in the axial direction.

[0016] The first yoke core 21 and the second yoke core 22 are arranged at intervals along the axis L. The first yoke core 21 and the second yoke core 22 each have a plurality of teeth 24, 25 that face the permanent magnet 11 in the radial direction. The teeth 24, 25 protrude in directions that bring them closer to each other. The teeth 24 are provided at equal intervals in the circumferential direction on the first yoke core 21, and the teeth 25 are provided at equal intervals in the circumferential direction on the second yoke core 22. The teeth 24 and the teeth 25 are arranged alternately in the circumferential direction.

[0017] The yoke holder 23 is made of, for example, a resin material and has a cylindrical shape. In this embodiment, the yoke holder 23 has a circular shape when viewed in the axial direction. The yoke holder 23 holds the first yoke core 21 and the second yoke core 22 so that, for example, the inner surfaces of the teeth 24, 25 are exposed on the inner periphery of the yoke holder 23.

[0018] The yoke holder 23 in this embodiment is a resin molded part formed by insert molding with the first yoke core 21 and the second yoke core 22 as insert parts. In other embodiments, the first yoke core 21 and the second yoke core 22 may not be insert parts, and the first yoke core 21 and the second yoke core 22 may be assembled to a separately formed yoke holder 23.

[0019] 1 and 2 , the fixed unit 13 includes a magnetic flux collector assembly 31, an outer case 32 that holds the magnetic flux collector assembly 31, two magnetic sensors 33 a and 33 b, and a circuit board 34 on which the magnetic sensors 33 a and 33 b are mounted. The fixed unit 13 is attached to the housing 3.

[0020] The magnetic flux collecting assembly 31 includes a first magnetic flux collecting member 41, a second magnetic flux collecting member 42, and a magnetic flux collecting holder 43 that holds the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42. The magnetic flux collecting assembly 31 may further include a shield member that is disposed on the outer periphery of the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42.

[0021] As shown in FIGS. 2 and 3 , the first magnetic flux collector 41 is disposed on the outer circumferential side of the first yoke core 21 with a gap between them. The first magnetic flux collector 41 includes an annular first main body portion 51 and two first protrusions 52a, 52b. In this embodiment, the first main body portion 51 has a C-shape when viewed in the axial direction. The first main body portion 51 faces the first yoke core 21 in the radial direction. The first protrusions 52a, 52b protrude radially outward from the first main body portion 51, i.e., toward the radially outward direction of the rotating shaft 2 perpendicular to the axis L. The first protrusions 52a, 52b are disposed at a predetermined gap between them in the circumferential direction. The first protrusions 52a, 52b have, for example, a rectangular plate shape when viewed in the axial direction. The first protrusions 52a and 52b have first opposing surfaces 53a and 53b, respectively, that axially face second protrusions 62a and 62b of the second magnetic flux collecting member 42, which will be described later (see FIG. 4).

[0022] The first magnetic flux collecting member 41 is formed, for example, by bending a long metal plate made of a magnetic material. In another embodiment, the first magnetic flux collecting member 41 may be divided into a member constituting the first main body portion 51 and a member constituting the first protrusions 52 a, 52 b.

[0023] The second magnetic flux collector 42 is disposed on the outer circumferential side of the second yoke core 22 with a gap between them. The second magnetic flux collector 42 has an annular second main body portion 61 and two second protrusions 62a, 62b. In this embodiment, the second main body portion 61 has a C-shape when viewed in the axial direction. The second main body portion 61 faces the second yoke core 22 in the radial direction. The second protrusions 62a, 62b protrude radially outward from the second main body portion 61, i.e., radially outward from the rotating shaft 2. The second protrusions 62a, 62b are disposed at a predetermined interval from each other in the circumferential direction. The second protrusions 62a, 62b have, for example, a rectangular plate shape when viewed in the axial direction. The second protrusions 62a, 62b have second opposing surfaces 63a, 63b that face the first protrusions 52a, 52b in the axial direction, respectively (see FIG. 4 ).

[0024] The second magnetic flux collecting member 42 is formed, for example, by bending a long metal plate made of a magnetic material. In another embodiment, the second magnetic flux collecting member 42 may be divided into a member that constitutes the second main body portion 61 and a member that constitutes the second protrusions 62a, 62b. Furthermore, although the second magnetic flux collecting member 42 in this embodiment has the same shape as the first magnetic flux collecting member 41, this is not limiting, and the second magnetic flux collecting member 42 may have a different shape from the first magnetic flux collecting member 41.

[0025] 1 and 2 , the magnetic flux collector holder 43 is made of, for example, a resin material and has a generally cylindrical shape. Specifically, the magnetic flux collector holder 43 has a cylindrical holder main body 71 and a first protruding wall 72 and a second protruding wall 73 provided on the outer peripheral surface of the holder main body 71. In this embodiment, the holder main body 71 has a circular shape when viewed in the axial direction. The first protruding wall 72 protrudes radially outward from one axial end of the holder main body 71. The second protruding wall 73 protrudes radially outward from the other axial end of the holder main body 71. The first protruding wall 72 faces the second protruding wall 73 with an axial gap between them.

[0026] The magnetic flux collector holder 43 holds the first magnetic flux collector member 41 so that the inner circumferential surface of the first main body portion 51 is exposed to the inner circumferential surface of the holder main body 71 and the first protrusions 52a, 52b protrude toward the outer circumferential side of the holder main body 71. As shown in FIGS. 2 and 4 , the first protruding wall 72 has first pedestal portions 74a, 74b that support the first protrusions 52a, 52b. The first pedestal portions 74a, 74b are shaped to expose, for example, the first opposing surfaces 53a, 53b of the first protrusions 52a, 52b and the side surfaces of the tip portions of the first protrusions 52a, 52b. In other words, the first pedestal portions 74a, 74b are shaped to cover, for example, the surfaces of the first protrusions 52a, 52b opposite the first opposing surfaces 53a, 53b and the side surfaces of the base end portions of the first protrusions 52a, 52b.

[0027] Furthermore, the magnetic flux collecting holder 43 holds the second magnetic flux collecting member 42 so that the inner peripheral surface of the second main body portion 61 is exposed to the inner peripheral surface of the holder main body 71 and the second protrusions 62a, 62b protrude toward the outer peripheral side of the holder main body 71. The second protruding wall 73 has second pedestal portions 75a, 75b that support the second protrusions 62a, 62b. The second pedestal portions 75a, 75b are shaped to expose, for example, the second opposing surfaces 63a, 63b of the second protrusions 62a, 62b and the side surfaces of the tip portions of the second protrusions 62a, 62b.

[0028] The magnetic flux collector holder 43 is a resin molded product formed by insert molding, for example, with the first magnetic flux collector member 41 and the second magnetic flux collector member 42 as insert parts. In other words, the magnetic flux collector holder 43 is a part of the magnetic flux collector assembly 31 made of a resin material. In other embodiments, the first magnetic flux collector member 41 and the second magnetic flux collector member 42 may not be insert parts, but may be assembled to a magnetic flux collector holder 43 that is formed separately. Furthermore, the magnetic flux collector holder 43 may be divided into a member that holds the first magnetic flux collector member 41 and a member that holds the second magnetic flux collector member 42, and these members may be assembled to each other.

[0029] The outer case 32 is a resin molded product formed by insert molding using the magnetic flux collector assembly 31 as an insert component. The outer case 32 has a cylindrical case main body 81 and a protruding portion 82 that protrudes radially outward from the magnetic flux collector assembly 31. In this embodiment, the case main body 81 has a circular shape when viewed in the axial direction. The case main body 81 mainly covers the outer peripheral surface of the holder main body 71 of the magnetic flux collector holder 43. The protruding portion 82 has, for example, a cylindrical shape and protrudes in a direction perpendicular to the axis L. In this embodiment, the protruding portion 82 has a rectangular shape when viewed in the direction perpendicular to the axial direction. The protruding portion 82 mainly covers the outer surfaces of the first protruding wall 72 and the second protruding wall 73 of the magnetic flux collector holder 43. The open end of the protruding portion 82 is closed by a cover (not shown).

[0030] The outer case 32 is attached immovably with respect to the housing 3. As a result, even if the rotating shaft 2 rotates, the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42 do not rotate. In this embodiment, the outer case 32 is attached to the housing 3 so that the first magnetic flux collecting member 41 is positioned above the second magnetic flux collecting member 42 in the direction of gravity. In other embodiments, the outer case 32 may be attached to the housing 3 so that the first magnetic flux collecting member 41 is positioned below the second magnetic flux collecting member 42 in the direction of gravity. The interior of the magnetic flux collecting holder 43 is in communication with the interior of the housing 3 via the case main body 81.

[0031] As shown in FIG. 4 , the magnetic sensors 33a and 33b are, for example, Hall sensors or magnetic resistance sensors, for detecting magnetic flux flowing through the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42. One of the magnetic sensors 33a and 33b is a redundant sensor to be used in case the other fails or otherwise malfunctions. The magnetic sensors 33a and 33b each include an element body 91a and 91b configured to detect magnetic flux and a connection terminal 92a and 92b connected to a wiring pattern on the circuit board 34. The magnetic sensor 33a is disposed on the circuit board 34 between the first protrusion 52a of the first magnetic flux collecting member 41 and the second protrusion 62a of the second magnetic flux collecting member 42. The magnetic sensor 33b is disposed on the circuit board 34 between the first protrusion 52b of the first magnetic flux collecting member 41 and the second protrusion 62b of the second magnetic flux collecting member 42.

[0032] 2 to 4, the circuit board 34 has, for example, a rectangular plate shape. The circuit board 34 is housed in the protruding portion 82 so that the thickness direction of the circuit board 34 is along the axis L. The circuit board 34 is electrically connected to a terminal (not shown) provided in the protruding portion 82.

[0033] 3 and 4 , the circuit board 34 has a first main surface 101 on which the first protrusions 52a and 52b are arranged, and a second main surface 102 on which the second protrusions 62a and 62b are arranged, i.e., opposite the first main surface 101. The magnetic sensors 33a and 33b are arranged on the edge of the circuit board 34. The circuit board 34 has recesses 103a and 103b at positions corresponding to the magnetic sensors 33a and 33b. In this embodiment, the recesses 103a and 103b have bottoms 104a and 104b, respectively, and do not penetrate the circuit board 34 in the thickness direction. In other words, the bottoms 104a and 104b close one end of the recesses 103a and 103b so that the recesses 103a and 103b do not penetrate the circuit board 34 in the thickness direction. The thickness of the bottom portions 104a and 104b is thinner than the thickness of other portions of the circuit board 34. In other words, the circuit board 34 has thin plate portions at positions corresponding to the magnetic sensors 33a and 33b that are thinner than the other portions.

[0034] Specifically, the recesses 103a, 103b are open to the second main surface 102 of the circuit board 34 and to a side surface 105 corresponding to the edge. In other words, when the circuit board 34 is viewed from above, the recesses 103a, 103b are rectangular in shape, with one side facing the second main body 61 of the second magnetic flux collecting member 42 being open and the other three sides being closed. The bottoms 104a, 104b close one end of the recesses 103a, 103b, respectively, so that the recesses 103a, 103b do not open to the first main surface 101. While the recesses 103a, 103b in this embodiment are rectangular in shape, the shape is not limited thereto, and may be, for example, semicircular, as long as the portion facing the second main body 61 of the second magnetic flux collecting member 42 is open, similar to the rectangular shape.

[0035] At least a portion of the magnetic sensors 33a and 33b is disposed within the recesses 103a and 103b, respectively. However, the width of the recesses 103a and 103b (in the horizontal direction in FIG. 4 ) need only be the minimum size required to accommodate at least a portion of the element bodies 91a and 91b of the magnetic sensors 33a and 33b, and the width should not be unnecessarily large. For ease of explanation, the connection terminals 92a and 92b are not shown in FIG. 3 . In this embodiment, most of the element bodies 91a and 91b of the magnetic sensors 33a and 33b and the entire connection terminals 92a and 92b are disposed within the recesses 103a and 103b, respectively. In other words, portions of the element bodies 91a and 91b protrude outside the recesses 103a and 103b, respectively. In another embodiment, the entire magnetic sensors 33a, 33b, i.e., the entire element bodies 91a, 91b and the entire connection terminals 92a, 92b, may be disposed within the recesses 103a, 103b, respectively. In this embodiment, the connection terminals 92a, 92b are connected to wiring patterns that extend to the bottoms 104a, 104b within the recesses 103a, 103b, respectively. In another embodiment, the tips of the connection terminals 92a, 92b may extend outside the recesses 103a, 103b, and the connection terminals 92a, 92b may be connected to wiring patterns outside the recesses 103a, 103b, respectively.

[0036] Furthermore, the magnetic sensors 33a and 33b are covered with potting resin materials 105a and 105b, respectively, which fill the recesses 103a and 103b. The potting resin materials 105a and 105b are made of, for example, silicone gel or epoxy resin. In this embodiment, the entire element bodies 91a and 91b and the entire connection terminals 92a and 92b are covered with the potting resin materials 105a and 105b, respectively. However, this is not limiting, and for example, only a portion of the element bodies 91a and 91b may be exposed from the potting resin materials 105a and 105b.

[0037] The circuit board 34 is assembled to the torque sensor 1 so that the magnetic sensors 33a, 33b are disposed between the first protrusions 52a, 52b and the second protrusions 62a, 62b, respectively. The entire first protrusions 52a, 52b are disposed outside the recesses 103a, 103b, respectively. The entire second protrusions 62a, 62b are disposed outside the recesses 103a, 103b, respectively. As a result, the arrangement is in the order of, from above in the direction of gravity, the first protrusions 52a, 52b, the bottoms 104a, 104b of the recesses 103a, 103b, the magnetic sensors 33a, 33b, and the second protrusions 62a, 62b.

[0038] (Operation of Torque Sensor 1) As described above, when the input shaft 4 and the output shaft 6 rotate relative to each other due to the torsion of the torsion bar 5 caused by the steering operation by the driver, the relative circumferential position of the permanent magnet 11 and the magnetic yoke assembly 12 changes. As a result, the magnetic flux flowing through the first yoke core 21 and the second yoke core 22 changes depending on the amount of torsion of the torsion bar 5, i.e., the magnitude of the torque input by the driver. As a result, the magnetic flux flowing through the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42 also changes depending on the change in the magnetic flux flowing through the first yoke core 21 and the second yoke core 22. The magnetic sensors 33a, 33b detect the magnetic flux flowing through the first magnetic flux collecting member 41 and the second magnetic flux collecting member 42 and generate a signal corresponding to this magnetic flux, i.e., a signal indicating torque.

[0039] Next, the operation and effects of this embodiment will be described. (1-1) Because at least a portion of the magnetic sensors 33a, 33b is disposed within the recesses 103a, 103b of the circuit board 34, the first protrusions 52a, 52b and the second protrusions 62a, 62b can be disposed close to each other. This prevents the gap between the first protrusions 52a, 52b and the second protrusions 62a, 62b from becoming large. Furthermore, the entire first protrusions 52a, 52b and the second protrusions 62a, 62b are disposed outside the recesses 103a, 103b. Therefore, even if the dimensional tolerances and assembly tolerances of the first magnetic flux collector 41, the second magnetic flux collector 42, and the circuit board 34 are not strictly controlled, the first protrusions 52a, 52b and the second protrusions 62a, 62b can be prevented from interfering with the circuit board 34.

[0040] (1-2) The recesses 103a, 103b have bottoms 104a, 104b, respectively, that close the recesses 103a, 103b so that they do not penetrate the circuit board 34 in the thickness direction. Therefore, a decrease in the strength of the circuit board 34 can be suppressed compared to when the recesses 103a, 103b are shaped to penetrate the circuit board 34 in the thickness direction, or when the entire circuit board 34 is made uniformly thin without providing recesses or notches in the circuit board 34. Furthermore, the bottoms 104a, 104b are located between the magnetic sensors 33a, 33b and the first protrusions 52a, 52b, respectively. In other words, the sides of the magnetic sensors 33a, 33b that face the first protrusions 52a, 52b are covered by the bottoms 104a, 104b, respectively. This makes it possible to prevent foreign matter such as metal pieces from adhering to the side of the magnetic sensors 33a, 33b facing the first protrusions 52a, 52b, compared to when the recesses 103a, 103b are shaped to penetrate through the plate thickness direction.

[0041] Here, assume that liquid such as rainwater enters the magnetic flux collector assembly 31 through the housing 3. In this case, there is a risk that the liquid may reach the magnetic sensors 33a, 33b through at least one of the interface between the first magnetic flux collector member 41 and the magnetic flux collector holder 43 and the interface between the second magnetic flux collector member 42 and the magnetic flux collector holder 43. In this regard, according to the above-described configuration, the bottoms 104a, 104b are respectively interposed between the magnetic sensors 33a, 33b and the first protrusions 52a, 52b. Therefore, for example, liquid that travels from the inner periphery of the magnetic flux collector holder 43 along the first main body portion 51 of the first magnetic flux collector member 41 and reaches the first protrusions 52a, 52b can be prevented from adhering to the magnetic sensors 33a, 33b.

[0042] (1-3) The torque sensor 1 is disposed around the rotating shaft 2 so that the first protrusions 52a, 52b are positioned above the second protrusions 62a, 62b in the direction of gravity. Liquids such as rainwater tend to move downward in the direction of gravity due to gravity. In this regard, in the present embodiment, the first protrusions 52a, 52b are positioned above the magnetic sensors 33a, 33b in the direction of gravity. However, because the bottoms 104a, 104b are interposed between the magnetic sensors 33a, 33b and the first protrusions 52a, 52b, respectively, as described above, liquids that reach the first protrusions 52a, 52b are less likely to adhere to the magnetic sensors 33a, 33b. Furthermore, the second protrusions 62a, 62b are positioned below the magnetic sensors 33a, 33b in the direction of gravity. Therefore, liquids that reach the second protrusions 62a, 62b are less likely to adhere to the magnetic sensors 33a, 33b. Therefore, in a torque sensor 1 having recesses 103a, 103b opening to the second main surface 102 of the circuit board 34 and having first protrusions 52a, 52b arranged within the recesses 103a, 103b, there is a great advantage in adopting a configuration in which the first protrusions 52a, 52b are arranged above the second protrusions 62a, 62b in the direction of gravity.

[0043] (1-4) The torque sensor 1 includes potting resin materials 105a and 105b that are filled into the recesses 103a and 103b so as to cover the magnetic sensors 33a and 33b. This effectively prevents foreign matter from adhering to the magnetic sensors 33a and 33b.

[0044] Second Embodiment Next, a second embodiment of the torque sensor 1 will be described with reference to the drawings. For ease of explanation, the same components as those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.

[0045] 5, the recesses 203a and 203b in this embodiment have a shape that penetrates through the circuit board 34 in the plate thickness direction. Specifically, the recesses 203a and 203b open to the first main surface 101, the second main surface 102, and the side surface 105 corresponding to the edge portion of the circuit board 34, respectively.

[0046] At least a portion of the magnetic sensors 33a and 33b is disposed in the recesses 103a and 103b, respectively. In this embodiment, the entire element bodies 91a and 91b of the magnetic sensors 33a and 33b, except for the tips of the connection terminals 92a and 92b, are disposed in the recesses 203a and 203b, respectively. In other embodiments, a portion of the element bodies 91a and 91b may be disposed outside the recesses 203a and 203b, respectively. The center positions of the element bodies 91a and 91b in the thickness direction may or may not coincide with the center positions of the recesses 203a and 203b in the thickness direction. In this embodiment, the connection terminals 92a and 92b are connected to wiring patterns provided on the first main surface 101, respectively. In other embodiments, the connection terminals 92a and 92b may be connected to wiring patterns provided on the second main surface 102, respectively.

[0047] The circuit board 34 is assembled to the torque sensor 1 so that the magnetic sensors 33a, 33b are disposed between the first protrusions 52a, 52b and the second protrusions 62a, 62b, respectively. As a result, the first protrusions 52a, 52b, the magnetic sensors 33a, 33b, and the second protrusions 62a, 62b are disposed in this order from above in the direction of gravity.

[0048] As described above, in addition to the same effects and advantages as those of (1-1) of the first embodiment, this embodiment also provides the following effects and advantages: (2-1) The recesses 203a, 203b are shaped to penetrate the circuit board 34 in the thickness direction. Therefore, the recesses 203a, 203b can be made deeper than when bottoms that close the recesses 203a, 203b are provided on the circuit board 34. This allows a larger portion of the magnetic sensors 33a, 33b to be disposed within the recesses 203a, 203b, and allows the first protrusions 52a, 52b and the second protrusions 62a, 62b to be disposed closer to each other.

[0049] The above-described embodiments can be modified as follows. The above-described embodiments and the following modified examples can be combined with each other to the extent that no technical contradiction occurs. In the first embodiment, the torque sensor 1 does not need to include the potting resin materials 105a and 105b. In the second embodiment, the recesses 203a and 203b may be filled with potting resin material, and at least a portion of the magnetic sensors 33a and 33b may be covered with the potting resin material.

[0050] The first protrusions 52 a, 52 b may protrude from the first main body 51 to one side in the axial direction, and the second protrusions 62 a, 62 b may protrude from the second main body 61 to the other side in the axial direction. In this case, the second protrusions 62 a, 62 b are arranged to face the first protrusions 52 a, 52 b with a radial gap therebetween. The circuit board 34 may also be arranged so that its thickness direction is perpendicular to the axis L.

[0051] The first magnetic flux collecting member 41 may have only one first protrusion. Similarly, the second magnetic flux collecting member 42 may have only one second protrusion. The fixed unit 13 may not have an outer case 32. Furthermore, the fixed unit 13 may have only one magnetic sensor.

[0052] The first magnetic flux collecting member 41 may be axially opposed to the first yoke core 21. In this case, the first main body portion 51 may be, for example, flat, and the shape thereof may be changed as appropriate. Similarly, the second magnetic flux collecting member 42 may be axially opposed to the second yoke core 22.

[0053] The shape of the magnetic flux collector holder 43 can be changed as appropriate. For example, the magnetic flux collector holder 43 does not need to have the first protruding wall 72 and the second protruding wall 73. The torque sensor 1 may be configured to detect the rotation angle of the rotating shaft 2 in addition to the torque. In this case, the torque sensor 1 further includes, for example, a driving gear provided in the magnetic yoke assembly 12 and one or more driven gears that mesh with the driving gear. The rotation angle of the rotating shaft 2 can then be detected based on the rotation angle of the driven gear.

[0054] Although the permanent magnet 11 is fixed to the input shaft 4 and the magnetic yoke assembly 12 is fixed to the output shaft 6, the permanent magnet 11 may be fixed to the output shaft 6 and the magnetic yoke assembly 12 may be fixed to the input shaft 4.

[0055] Next, the technical ideas that can be understood from the above-described embodiments and modified examples are additionally described below: (Supplementary Note 1) A torque sensor in which the magnetic sensor is arranged on an edge portion of the circuit board, the circuit board has a first main surface on which the first protrusion is arranged and a second main surface opposite to the first main surface, and the recess opens to the second main surface and a side surface of the circuit board that corresponds to the edge portion, but does not open to the first main surface.

[0056] (Supplementary Note 2) A torque sensor, wherein the magnetic sensor is arranged on an edge portion of the circuit board, the circuit board has a first main surface on which the first protrusion is arranged and a second main surface opposite the first main surface, and the recess opens to the first main surface, the second main surface, and a side surface of the circuit board corresponding to the edge portion.

Claims

1. A torque sensor configured to detect a torque applied to a rotating shaft, the rotating shaft including a first shaft and a second shaft coupled to the first shaft via a torsion bar, the torque sensor comprising: a permanent magnet configured to rotate integrally with the first shaft; a first yoke core and a second yoke core configured to rotate integrally with the second shaft; a first magnetic flux collecting member disposed with a gap between it and the first yoke core, and a second magnetic flux collecting member disposed with a gap between it and the second yoke core; a magnetic sensor configured to generate a signal according to magnetic flux flowing through the first magnetic flux collecting member and the second magnetic flux collecting member; a circuit board on which the magnetic sensor is mounted, the first magnetic flux collecting member has a first main body portion facing the first yoke core and a first protrusion protruding from the first main body portion, the second magnetic flux collecting member has a second main body portion facing the second yoke core, and a second protrusion protruding from the second main body portion and facing the first protrusion, the magnetic sensor is disposed on the circuit board between the first protrusion and the second protrusion, the circuit board has a recess at a position corresponding to the magnetic sensor; At least a portion of the magnetic sensor is disposed within the recess; the first protrusion and the second protrusion are each entirely disposed outside the recess; The recess has a bottom that closes the recess so as not to penetrate the circuit board in the thickness direction.

2. 2. The torque sensor according to claim 1, A torque sensor comprising: a potting resin material filled in the recess so as to cover the magnetic sensor.

3. 3. The torque sensor according to claim 1, The torque sensor is provided around the rotating shaft so that the first protrusion is positioned higher than the second protrusion in a direction of gravity.

4. (delete)

5. (delete)