Stroke sensor

Abstract

To provide a compact stroke sensor capable of detecting a stroke position highly precisely.SOLUTION: A stroke sensor 1 includes: two disk-shaped rotors 2 rotated following a stroke of a rack shaft 13 as a measured member; a rotation detection part 3 for detecting rotation of the two rotors 2, respectively; and a stroke position detection part 4 for obtaining a stroke position of the rack shaft 13 on the basis of rotation of the two rotors 2 detected by the rotation detection part 3. At least one of the two rotors 2 is provided while directly abutting on the rack shaft 13. The two rotors 2 are provided while being lined up in an array direction vertical to an axial direction of the rack shaft 13 and is provided while being adjacent to the rack shaft 13 in an array vertical direction vertical to the axial direction and the array direction, and each of the two rotors is provided such that its rotation axis direction is inclined relative to the array direction when seen from the axial direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a stroke sensor.

Background Art

[0002] In recent years, the application of steer-by-wire to automobiles has been progressing. In steer-by-wire, unlike conventional steering mechanisms, the steering wheel and the steering mechanism are not mechanically connected, but are electrically connected. Therefore, by applying steer-by-wire, the degree of freedom in automotive interior design can be increased, the weight of the steering mechanism can be reduced, and further, there is a feature that the road surface reaction force from the wheels is not directly received by the steering wheel.

[0003] Note that as prior art document information related to the invention of this application, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above-mentioned steer-by-wire, in order to reproduce the delicate steering and turning performed by a person, high-precision control is required, and it is required to accurately obtain the steering angle. In order to accurately obtain the steering angle, that is, it is required to accurately obtain the displacement (stroke position) in the axial direction of the rack shaft. That is, a stroke sensor capable of accurately detecting the stroke position of the rack shaft is required.

[0006] Further, the stroke sensor is housed inside a housing that houses the rack shaft. Inside the housing, the space for housing the stroke sensor is limited, and a compact stroke sensor is required.

[0007] Therefore, an object of the present invention is to provide a stroke sensor that is small in size and capable of detecting a stroke position with high accuracy.

Means for Solving the Problems

[0008] The present invention is a sensor for detecting the stroke position of a rod-shaped member to be measured that strokes in the axial direction, and is intended to solve the above problems. The sensor includes two disk-shaped rotators that rotate as the member to be measured strokes, a rotation detection unit that detects the rotation of each of the two rotators, and a stroke position detection unit that obtains the stroke position of the member to be measured based on the rotation of the two rotators detected by the rotation detection unit. At least one of the two rotators is provided in direct contact with the member to be measured. The two rotators are arranged side by side in an arrangement direction perpendicular to the axial direction of the member to be measured, and are provided so as to be adjacent to the member to be measured in an arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction. Further, when viewed from the axial direction, each of the two rotators is provided such that its rotation axis direction is inclined with respect to the arrangement direction. A stroke sensor is provided.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a stroke sensor that is small in size and capable of detecting a stroke position with high accuracy.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

[0011] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] (Steering device 10) FIG. 1(a) is a schematic diagram of a steering device 10 including a stroke sensor 1 according to the present embodiment, and FIG. 1(b) is a cross-sectional view taken along line A-A thereof.

[0013] As shown in FIG. 1(a), the steering device 10 includes a tie rod 12 connected to a rolling wheel 11 (such as a front wheel of an automobile), a rack shaft 13 connected to the tie rod 12, a housing 14 that houses the rack shaft 13, a motor 15 that drives the rack shaft 13, and a steering mechanism 16 that includes a steering wheel and the like. In this steering device 10, the motor 15 is driven according to a steering operation by the steering mechanism 16, and the rack shaft 13 is stroked in the axial direction (the left-right direction in the drawing) to roll the rolling wheel 11 and perform steering. The rack shaft 13 has a tooth portion (rack) 13a formed with teeth at equal intervals along the axial direction, and a pinion 15a driven by the motor 15 meshes with the tooth portion 13a to constitute a rack and pinion mechanism.

[0014] As shown in Fig. 1(b), the rack shaft 13 has a shape in which a part is cut out in a cross section perpendicular to the axial direction, and its outer peripheral surface is composed of a straight portion 13b and an arc portion 13c. A tooth portion 13a is formed on the flat portion of the outer peripheral surface of the rack shaft 13 corresponding to the straight portion 13b. The rack shaft 13 is a member to be detected for the stroke position by the stroke sensor 1 according to the present embodiment, and corresponds to the member to be measured of the present invention.

[0015] (Stroke sensor 1) The stroke sensor 1 is a sensor that detects the stroke position (displacement) of the rack shaft 13 as a rod-shaped member to be measured that strokes in the axial direction. The stroke sensor 1 includes two rotators 2, a rotation detection unit 3, a stroke position detection unit 4, and a support member 5.

[0016] (Rotator 2) The rotator 2 is a member that rotates along with the stroke of the rack shaft 13 as a member to be measured, and is formed in a disc shape. In the present embodiment, two rotators 2, i.e., a first rotator 21 and a second rotator 22, are used. In the stroke sensor 1, the stroke of the rack shaft 13 is converted into the rotation of the first and second rotators 21 and 22, and the stroke position of the rack shaft 13 is detected based on the rotation of the first and second rotators 21 and 22.

[0017] So as to rotate along with the stroke of the rack shaft 13, the rotation axes of the first and second rotators 21 and 22 are provided so as to be perpendicular to the stroke direction, that is, the axial direction of the rack shaft 13.

[0018] In the stroke sensor 1, in order to accurately detect the stroke position of the rack shaft 13, at least one of the two rotators 2 is provided in direct contact with the rack shaft 13. In the present embodiment, both the first and second rotators 21 and 22 are in direct contact with the rack shaft 13.

[0019] More specifically, in the present embodiment, both the first and second rotors 21 and 22 are formed of gears that directly mesh with the tooth portion 13a of the rack shaft 13. Note that the tooth portion 13a of the rack shaft 13 is used to stroke the rack shaft 13 with the motor 15 as described above. In the present embodiment, this tooth portion 13a is also used in combination for detecting the stroke position.

[0020] In the stroke sensor 1 according to the present embodiment, the two rotors 21 and 22 are arranged side by side in an arrangement direction perpendicular to the axial direction of the rack shaft 13, and are provided so as to be adjacent to the rack shaft 13 in an arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction. And when viewed from the axial direction, each of the two rotors 21 and 22 is provided such that its rotation axis direction is inclined with respect to the arrangement direction.

[0021] When a rectangular coordinate system composed of the X-axis, Y-axis, and Z-axis is defined, the Z-axis direction corresponds to the "axial direction", the Y-axis direction corresponds to the "arrangement direction", and the X-axis direction corresponds to the "arrangement perpendicular direction". That is, in the stroke sensor 1, when the axial direction of the rack shaft 13 is the Z-axis direction, both rotors 21 and 22 are arranged side by side in the Y-axis direction, both rotors 21 and 22 and the rack shaft 13 are adjacent to each other in the Y-axis direction, and the rotation axis directions of both rotors 21 and 22 are inclined with respect to the Y-axis direction.

[0022] Thereby, it is possible to suppress the rotors 21 and 22 from protruding greatly outward in the radial direction of the rack shaft 13, and the entire stroke sensor 1 can be downsized. Although the space in the housing 14 of the steering apparatus 10 is very small, even in such a limited space in the housing 14, a compact steering apparatus 10 that can be accommodated compactly on one side of the rack shaft 13 can be realized.

[0023] Since both rotors 21 and 22 are inclined with respect to the tooth portion 13a of the rack shaft 13, it is preferable to use bevel gears in which the toothed surfaces are formed in a conical shape as the two rotors 21 and 22.

[0024] In this embodiment, the two rotors 21 and 22 are arranged such that their rotation axes intersect each other. Although details will be described later, in this embodiment, in order to detect the rotation of the rotors 21 and 22 using magnetism and avoid magnetic interference, the two rotors 21 and 22 are arranged such that their rotation axes are orthogonal to each other (the straight lines along the rotation axes are perpendicular to each other). Note that details regarding this point will be described later. However, a certain error is allowed in the angle formed by the rotation axes of the two rotors 21 and 22. Specifically, the angle formed by the rotation axes of the two rotors 21 and 22 may be 80° or more and 100° or less.

[0025] The two rotors 21 and 22 are arranged such that their rotation axes are at the same position in the axial direction (X-axis direction) of the rack shaft 13 (that is, the rotation axes are aligned in the Y-axis direction). Also, the angles at which the rotation axes are inclined with respect to the arrangement direction (Y-axis direction) of the two rotors 21 and 22 are the same angle (45°) for the two rotors 21 and 22. Furthermore, when viewed from the axial direction of the rack shaft 13, the two rotors 21 and 22 are inclined such that the distance between the two rotors 21 and 22 gradually increases from the outside to the inside in the radial direction of the rack shaft 13. The two rotors 21 and 22 are supported in a rotatable state by the support member 5. Details of the support member 5 will be described later.

[0026] Furthermore, in this embodiment, the outer diameters (number of teeth) of the first rotor 21 and the second rotor 22 are made different. Here, the outer diameter (number of teeth) of the first rotor 21 is larger than the outer diameter (number of teeth) of the second rotor 22. The reason for this will be described later.

[0027] (Rotation detection unit 3) The rotation detection unit 3 detects the rotation of the two rotors 21 and 22 respectively. The rotation detection unit 3 includes two rotor-side substrates 31, two detection coils 32, and two detection circuits 33.

[0028] The rotating body side substrate 31 is integrally provided on the axial end faces of the two rotating bodies 21 and 22, respectively, and rotates together with the corresponding rotation of the rotating bodies 21 and 22. In the present embodiment, disc-shaped rotating body side substrates 31 are integrally provided on the axial end faces of the rotating bodies 21 and 22 on the side opposite to the rack shaft 13 in the rotating bodies 21 and 22 so as to be coaxial with the rotating bodies 21 and 22. The rotating body side substrate 31 is formed smaller than the outer diameters of the corresponding rotating bodies 21 and 22 (more specifically, smaller than the outer diameter at the bottom of the teeth).

[0029] As shown in FIG. 2, the rotating body side substrate 31 has a conductor pattern 31a formed in a predetermined pattern along the circumferential direction of the rotating bodies 21 and 22. In the illustrated example, the conductor pattern 31a is formed so that the thickness along the radial direction of the rotating bodies 21 and 22 gradually changes along the circumferential direction of the rotating bodies 21 and 22, and the conductor pattern 31a is formed so that the thickest portion and the thinnest portion face each other in the radial direction. In the present embodiment, since the outer diameters (number of teeth) of the first rotating body 21 and the second rotating body 22 are different, the sizes of the rotating body side substrate 31 and the conductor pattern 31a also differ accordingly. However, the pattern configuration of the conductor pattern 31a itself is the same pattern configuration in the circumferential direction of the rotating bodies 21 and 22.

[0030] The two detection coils 32 are respectively provided so as to face the corresponding rotating body side substrate 31. Both detection coils 32 are fixedly provided so as not to rotate with the rotation of the rotating bodies 21 and 22. When an alternating voltage is applied to the detection coil 32, eddy currents are generated in the conductor pattern 31a facing the detection coil 32 by the magnetic field generated in the detection coil 32. Then, the inductance of the detection coil 32 changes due to the magnetic field generated by the eddy currents generated in the conductor pattern 31a. Since this change in the inductance of the detection coil 32 changes depending on the shape of the conductor pattern 31a, etc. (here, the thickness along the radial direction of the rotating bodies 21 and 22), based on this change in the inductance of the detection coil 32, the rotation angles of the corresponding rotating bodies 21 and 22 can be detected respectively.

[0031] The detection coil 32 is arranged such that the direction of the magnetic field (magnetic field generation direction) generated by the detection coil 32 is parallel to the rotation axes of the rotors 21 and 22. Further, in the present embodiment, the two detection coils 32 are arranged such that the magnetic field generation directions are orthogonal to each other (the rotation axes of the two rotors 21 and 22 parallel to the magnetic field generation directions of both detection coils 32 are also orthogonal to each other). Thereby, it becomes possible to suppress the magnetic field generated by the detection coil 32 corresponding to one rotor 2 (for example, the first rotor 21) from affecting the detection coil 32 corresponding to the other rotor 2 (for example, the second rotor 22), and it becomes possible to improve the detection accuracy. In the present embodiment, one detection coil 32 is provided for each of the rotors 21 and 22, but two or more detection coils 32 may be provided for each of the rotors 21 and 22. That is, the number of detection coils 32 provided for each of the rotors 21 and 22 is preferably one or more.

[0032] The detection circuit 33 is a circuit that detects the rotation angles of the corresponding rotors 21 and 22 based on the changes in the inductances of both detection coils 32 when an AC voltage is applied to each of the detection coils 32. In the present embodiment, the detection circuit 33 is configured to detect the change in the inductance of the detection coil 32 based on the change in the resonance frequency.

[0033] FIG. 3 is a circuit diagram showing an example of the detection circuit 33. In FIG. 3, the inductance of the detection coil 32 is denoted as Lc, the inductance generated in the conductor pattern 31a is denoted as Le, the resistance of the conductor pattern 31a is denoted as Re, and the mutual inductance between the detection coil 32 and the conductor pattern 31a is denoted as M.

[0034] The detection circuit 33 includes a resistor Rs connected in series with the detection coil 32, a capacitive element Cp connected in parallel to the detection coil 32 and the resistor Rs connected in series, a resonance frequency detection unit 33b that detects the resonance frequency of a resonance circuit 33a composed of the detection coil 32, the resistor Rs, and the Cp, and a rotation angle calculation unit 33c that obtains the rotation angles of the rotors 21 and 22 based on the resonance frequency detected by the resonance frequency detection unit 33b.

[0035] In the circuit of FIG. 3, the resonance frequency f0 of the resonance circuit 33a detected by the resonance frequency detection unit 33b of the detection circuit 33 can be expressed by the following equation.

Equation

[0036] Based on the resonance frequency f0 detected by the resonance frequency detection unit 33b, the rotation angle calculation unit 33c detects a change in the inductance Lc of the detection coil 32 according to the influence of the conductor pattern 31a facing the detection coil 32, and obtains the rotation angles of the rotors 21 and 22, respectively.

[0037] As shown in FIG. 1(b), the detection circuit 33 and the detection coil 32 are mounted on the fixed-side circuit board 34. The fixed-side circuit board 34 is provided to face the rotor-side board 31 and is fixed to the housing 14 via the support member 5.

[0038] (Stroke position detection unit 4) Based on the rotations (rotation angles) of the two rotors 21 and 22 detected by the detection circuit 33, the stroke position detection unit 4 obtains the stroke position of the rack shaft 13 by calculation. The stroke position detection unit 4 is realized by appropriately combining arithmetic elements such as a CPU, a memory, software, an interface, and the like.

[0039] As described above, in this embodiment, the outer diameters (number of teeth) of the two rotors 21 and 22 are made different, and the rotational angles when the rack shaft 13 is stroked are configured to be different between the two rotors 21 and 22. Therefore, based on the rotational angles of both these rotors 21 and 22, it is possible to detect the stroke position with high precision. Further, by appropriately varying the detection periods (the rotational periods of the conductor patterns 31a according to the number of teeth of the rotors 21 and 22) of both rotors 21 and 22, it is possible to detect the stroke position even at a stroke length longer than the lengths of the outer circumferences of the respective rotors 21 and 22. Therefore, for example, even when using relatively small rotors 21 and 22, it is possible to accurately detect the stroke position of the rack shaft 13.

[0040] The stroke position detection unit 4 may be mounted, for example, on an electronic control unit of an automobile. In this case, the fixed-side circuit board 34 equipped with the detection circuit 33 and the electronic control unit are appropriately connected by a cable or the like. Note that this is not limiting, and the stroke position detection unit 4 may be configured separately from the electronic control unit of the automobile and may be configured to output the detected stroke position of the rack shaft 13 to the electronic control unit. For example, the stroke position detection unit 4 may be mounted on the fixed-side circuit board 34 or may constitute a dedicated unit separate from the electronic control unit.

[0041] (Support member 5) The support member 5 is for supporting the rotors 21 and 22 and the fixed-side circuit board 34, and it is preferable to use a non-magnetic material such as resin. The support member 5 integrally has a linear fixing portion 51 fixed to the housing 14 of the steering device 10 and a pair of arm portions 52 extending from both ends of the fixing portion 51 toward the rack shaft 13.

[0042] The fixing portion 51 is fixed to the housing 14 by a fixing member 53 such as a bolt. The arm portion 52 has a parallel portion 52a extending vertically from the fixing portion 51 and an inclined portion 52b extending inward (toward the opposing arm portion 52 side) from the tip of the parallel portion 52a. Rotating bodies 21 and 22, which are bevel gears, are rotatably attached to the tip of the inclined portion 52b with respect to the inclined portion 52b. A fixed-side circuit board 34 is fixed to the inclined portion 52b on the parallel portion 52a side of the rotating bodies 21 and 22.

[0043] Figure 4 is a diagram showing an example of the support structure of the rotating body 2 by the support member 5. As shown in Figure 4, the tip of the arm portion 52 of the support member 5 is inserted into a through hole 2a formed at the center of the rotating body 2, and a pair of flange portions 52c are formed so as to sandwich the through hole 2a. The rotating body 2 is rotatably supported by the support member 5 due to interference of this pair of flange portions 52c with the support member 5 at the periphery of the through hole 2a. Note that the specific shape of the support member 5 is not limited to the one shown in the figure and can be appropriately changed according to the arrangement of each member, the shape of the housing 14, etc. That is, the support member 5 only needs to be able to rotatably support at least the rotating bodies 21 and 22, support the fixed-side circuit board 34, and be fixed to the housing 14. Furthermore, the support member 5 for supporting the rotating bodies 21 and 22 and the support member 5 for supporting the fixed-side circuit board 34 may be configured separately.

[0044] (Modification example) In this embodiment, the case where both the first and second rotors 21 and 22 are gears that directly mesh with the tooth portion 13a of the rack shaft 13 has been described. However, it is not limited to this, and at least one of the first and second rotors 21 and 22 may be a gear that directly meshes with the tooth portion 13a of the rack shaft 13. For example, as shown in FIG. 5(a), one rotor 2 (here, the first rotor 21) may be a gear that directly meshes with the tooth portion 13a, and the other rotor 2 (here, the second rotor 22) may be a gear that meshes with one rotor 2 (here, the first rotor 21). Note that, for example, one or more gears may be interposed between the first rotor 21 and the second rotor 22, but this is not preferable because it may cause an increase in cost and may easily cause failures.

[0045] Furthermore, as shown in FIG. 5(b), only the detection coil 32 may be provided on the fixed-side circuit board 34, and the detection circuit 33 may be integrally mounted on a common board 35 provided separately from the fixed-side circuit board 34. The fixed-side circuit board 34 and the common board 35 are electrically connected by a wire 36. In this case, a part of the detection circuit 33 may be mounted on the fixed-side circuit board 34.

[0046] Also, in this embodiment, the outer diameters (number of teeth) of the two rotors 21 and 22 are made different, but it is not limited to this. As shown in FIG. 6(a), the outer diameters (number of teeth) of the two rotors 21 and 22 may be the same. That is, the two rotors 21 and 22 may be configured such that the rotation angles when the rack shaft 13 is stroked are the same. In this case, in order to make the detection periods of the two rotors 21 and 22 different, the conductor patterns 31a corresponding to the two rotors 21 and 22 are preferably formed to have different pattern configurations in the circumferential direction of the rotors 21 and 22. In the illustrated example, in one rotor 2 (the first rotor 21), the positions where the conductor pattern 31a is thickest and thinnest are each one at 180° intervals, but in the other rotor 2 (the second rotor 22), the thickest and thinnest positions are alternately formed every 90°. Thereby, the same effect as the case where the outer diameters (number of teeth) of the two rotors 21 and 22 are made different can be obtained.

[0047] Furthermore, in the present embodiment, the thickness of the conductor pattern 31a is gradually changed along the circumferential direction of the rotating body 2. However, the present invention is not limited to this. For example, as shown in FIG. 6(b), the conductor pattern 31a may have a constant thickness and be formed at predetermined intervals in the circumferential direction of the rotating body 2 in a pattern configuration.

[0048] In addition, in the present embodiment, a case where a part of the rack shaft 13 is cut out and a tooth portion 13a is formed thereon has been described. However, as shown in FIG. 7, the cross-sectional shape perpendicular to the axial direction of the rack shaft 13 may be circular, and a tooth portion 13a having a helical tooth may be formed on the outer peripheral surface thereof. In this case, a crown gear may be used as the two rotating bodies 21 and 22.

[0049] (Operations and Effects of the Embodiment) As described above, in the stroke sensor 1 according to the present embodiment, two disk-shaped rotating bodies 2 that rotate along with the stroke of the rack shaft 13, which is a member to be measured, a rotation detection unit 3 that detects the rotation of each of the two rotating bodies 2, and a stroke position detection unit 4 that obtains the stroke position of the rack shaft 13, which is a member to be measured, based on the rotation of the two rotating bodies 2 detected by the rotation detection unit 3 are provided. At least one of the two rotating bodies 2 is provided in direct contact with the rack shaft 13, which is a member to be measured. The two rotating bodies 2 are arranged side by side in an arrangement direction perpendicular to the axial direction of the rack shaft 13, which is a member to be measured, and are provided so as to be adjacent to the rack shaft 13, which is a member to be measured, in an arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction. Further, when viewed from the axial direction, each of the two rotating bodies 2 is provided such that its rotation axis direction is inclined with respect to the arrangement direction.

[0050] By detecting the stroke position using two rotating bodies 2, the detection accuracy can be improved. Also, by arranging the two rotating bodies 2 in an inclined manner, it is possible to suppress the rotating bodies 21 and 22 from protruding radially outward of the rack shaft 13, and the entire stroke sensor 1 can be miniaturized. That is, according to the present embodiment, it is possible to realize a stroke sensor 1 that can detect the stroke position with high accuracy and in a small size. Further, in the stroke sensor 1, at least one of the rotating bodies is in direct contact with the rack shaft 13, and since the stroke (displacement) of the rack shaft 13 is directly obtained, it is possible to detect the stroke position with high accuracy.

[0051] Also, in the present embodiment, the rotation of the rotating body 2 is detected by a method using magnetism by the detection coil 32 and the conductor pattern 31a. Therefore, it is not affected by grease or the like in the housing 14 of the steering device 10, and the stroke position can be detected accurately.

[0052] (Other embodiments) The stroke sensor 1a shown in FIG. 8 has basically the same configuration as the stroke sensor 1 in FIG. 1(b), but the configuration of the rotation detection unit 3 is different. In the stroke sensor 1a, the rotation detection unit 3 includes two magnets 61 provided integrally with the two rotating bodies 21 and 22 respectively, magnetic detection elements 62 provided so as not to rotate as the rotating bodies 21 and 22 rotate and detecting the magnetic field from the two magnets 61, and a detection circuit 63 that detects the rotation angle of the corresponding rotating bodies 21 and 22 based on the detection results of the magnetic detection elements 62.

[0053] The magnet 61 is provided integrally with the axial end face of the corresponding rotating body 21 or 22 and rotates together with the rotating body 21 or 22. As shown in FIG. 9, in the present embodiment, a columnar (disk-shaped) magnet 61 in which N poles and S poles are formed along the circumferential direction of the rotating bodies 21 and 22 is provided. Note that the shape of the magnet 61 is not limited to that shown in the figure, and for example, a bar-shaped magnet 61 may be used. Also, a ring-shaped magnet 61 in which a plurality of N poles and S poles are formed along the circumferential direction of the rotating bodies 21 and 22 may be used.

[0054] In the stroke sensor 1a, two magnetic detection elements 62 are used corresponding to the two rotating bodies 21 and 22. Both magnetic detection elements 62 are arranged to face the axial end faces (the axial end faces on the side where the magnets 61 are provided) of the corresponding rotating bodies 21 and 22, and detect the magnetic field (magnetic field strength) from the magnets 61. As the magnetic detection element 62, for example, a Hall element can be used. The magnetic detection element 62 is mounted on the fixed-side substrate 64, and the fixed-side substrate 64 is fixed to the housing 14 via the support member 5. In FIGS. 8 and 9, the detection axis of the magnetic detection element 62 is represented by the symbol D.

[0055] The two magnetic detection elements 62 are provided to detect a magnetic field in a direction perpendicular to the rotational axis direction of the corresponding rotating bodies 21 and 22. And the two rotating bodies 21 and 22 are arranged such that their rotational axes are orthogonal to each other. That is, the two rotating bodies 21 and 22 are arranged such that the detection directions (detection axes D) of the magnetic fields are orthogonal to each other. Thereby, it becomes possible to suppress the magnetic field generated by the magnet 61 corresponding to one rotating body 2 (for example, the first rotating body 21) from affecting the magnetic detection element 62 corresponding to the other rotating body 2 (for example, the second rotating body 22), and it becomes possible to improve the detection accuracy.

[0056] In the illustrated example, the magnetic detection element 62 is arranged at a position on the extension line of the rotational axis of the rotating bodies 21 and 22 (the central position of the rotating bodies 21 and 22 as viewed from the rotational axis direction). However, depending on the structure of the support member 5 and the like, there may be a case where it is difficult to arrange the magnetic detection element 62. In such a case, the magnetic detection element 62 may be arranged at a position slightly deviated from the position on the extension line of the rotational axis of the rotating bodies 21 and 22 (the central position of the rotating bodies 21 and 22 as viewed from the rotational axis direction).

[0057] The detection circuit 63 detects the rotation angle of the corresponding rotating bodies 21 and 22 based on the magnetic field strength detected by the magnetic detection element 62. The detection circuit 63 is mounted on the fixed-side substrate 64.

[0058] (Operations and effects of other embodiments) In the stroke sensor 1a of FIG. 8, instead of the rotating body side substrate 31 and the detection coil 32 in the stroke sensor 1 of FIG. 1(b), magnets 61 and magnetic detection elements 62 are used to detect the rotation of the rotating bodies 21 and 22. By configuring in this way, the same effects as those of the stroke sensor 1 in FIG. 1 can be obtained. That is, according to the stroke sensor 1a, it is possible to detect the stroke position with miniaturization and high precision, and it is possible to detect the stroke position with high precision without being affected by grease or the like inside the housing 14.

[0059] (Modification of Other Embodiments) In FIG. 8, the case of using two magnetic detection elements 62 has been described, but it may be configured to use one biaxial magnetic detection element 62. For example, as shown in FIG. 10(a), when the distance between the rotating bodies 21 and 22 gradually increases as it approaches the rack shaft 13, magnets 61 are provided on the axial end faces on the rack shaft 13 side of the rotating bodies 21 and 22, respectively, and the magnetic detection element 62 may be arranged at the position where the rotation axes of both rotating bodies 21 and 22 intersect. And the magnetic detection element 62 may be arranged such that its two detection axes D are perpendicular to the rotation axes of both rotating bodies 21 and 22, respectively.

[0060] Also, as shown in FIG. 10(b), it is also possible to arrange the rotating bodies 21 and 22 such that the distance between the rotating bodies 21 and 22 gradually increases as it moves away from the rack shaft 13. In this case, magnets 61 are provided on the axial end faces on the side of the rotating bodies 21 and 22 that do not face the rack shaft 13, respectively, and the magnetic detection element 62 may be arranged at the position where the rotation axes of both rotating bodies 21 and 22 intersect. And the magnetic detection element 62 may be arranged such that its two detection axes D are perpendicular to the rotation axes of both rotating bodies 21 and 22, respectively.

[0061] (Summary of Embodiments) Next, the technical idea grasped from the above-described embodiments will be described by referring to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description are not limited to the members and the like that specifically show the components in the claims in the embodiments.

[0062] [1] A sensor for detecting the stroke position of a rod-shaped measurement member (13) that strokes in the axial direction, comprising: two disk-shaped rotators (2) that rotate as the measurement member (13) strokes; a rotation detection unit (3) that detects the rotation of each of the two rotators (2); and a stroke position detection unit (4) that obtains the stroke position of the measurement member (13) based on the rotation of the two rotators (2) detected by the rotation detection unit (3). At least one of the two rotators (2) is provided in direct contact with the measurement member (13). The two rotators (2) are arranged side by side in an arrangement direction perpendicular to the axial direction of the measurement member (13), and are provided so as to be adjacent to the measurement member (13) in an arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction. Further, when viewed from the axial direction, each of the two rotators (2) is provided such that its rotation axis direction is inclined with respect to the arrangement direction. Stroke sensor (1).

[0063] [2] The rotation detection unit (3) includes two rotator-side substrates (31) that are integrally provided on the end faces in the rotation axis direction of the two rotators (2) respectively, and each has a conductor pattern (31a) formed in a predetermined pattern along the circumferential direction of the rotator (2). Two detection coils (32) are provided so as to face the two rotator-side substrates (31) respectively, and are provided so as not to rotate as the rotator (2) rotates. A detection circuit (33) that detects the rotation angle of the corresponding rotator (2) based on the change in the inductance of the detection coil (32) when an AC voltage is applied to each detection coil (32). The stroke sensor (1) according to [1].

[0064] [3] The two rotators (2) are arranged such that their rotation axes are orthogonal to each other, and the two detection coils (32) are arranged such that the magnetic field generation directions when the AC voltage is applied are orthogonal to each other. The stroke sensor (1) according to [2].

[0065] [4] The two rotating bodies (2) are configured such that the rotation angles when the member to be measured (13) is stroked are different from each other, and the conductor patterns (31a) formed on the rotating body side substrates (31) provided on the two rotating bodies (2) are formed to have the same pattern configuration in the circumferential direction of the rotating body (2). The stroke sensor (1) according to [2] or [3].

[0066] [5] The two rotating bodies (2) are configured such that the rotation angles when the member to be measured (13) is stroked are the same, and the conductor patterns (31a) formed on the rotating body side substrates (31) provided on the two rotating bodies (2) are formed to have different pattern configurations in the circumferential direction of the rotating body (2). The stroke sensor (1) according to [2] or [3].

[0067] [6] The rotation detection unit (3) includes two magnets (61) respectively provided integrally with the two rotating bodies (2), magnetic detection elements (62) respectively provided so as not to rotate as the rotating body (2) rotates and detecting magnetic fields from the two magnets (61), and a detection circuit (63) that detects the rotation angle of the corresponding rotating body (61) based on the detection results of the magnetic detection elements (62). The stroke sensor (1a) according to [1].

[0068] [7] The two rotating bodies (2) are arranged such that their rotation axes are orthogonal to each other, the magnetic field detection directions are orthogonal to each other, and the stroke sensor (1a) according to [6] having two magnetic detection elements (62) that respectively detect the magnetic fields of the corresponding magnets (61).

[0069] [8] The two rotating bodies (2) are arranged such that their rotation axes are orthogonal to each other, the magnetic detection element (62) is configured to be able to detect magnetic fields in two directions orthogonal to each other, and the stroke sensor (1a) according to [6] that detects the magnetic fields of the two magnets (61) in the two directions respectively.

[0070] [9] The two magnets (61) have the same configuration, and the two rotors (2) are configured such that the rotation angles when the member to be measured (13) is stroked are different from each other. The stroke sensor (1) according to any one of [6] to [8].

[0071]

[10] The member to be measured (13) has a tooth portion (13a) with teeth formed at equal intervals in the axial direction on at least a part of its outer peripheral surface. At least one of the two rotors (2) is a gear that directly meshes with the tooth portion (13a). The stroke sensor (1) according to any one of [1] to [9].

[0072]

[11] Both of the two rotors (2) are gears that directly mesh with the tooth portion (13a). The stroke sensor (1) according to

[10] .

[0073]

[12] One of the two rotors (2) is a gear that directly meshes with the tooth portion (13a), and the other of the two rotors (2) is a gear that directly meshes with one of the rotors (2). The stroke sensor (1) according to

[10] .

[0074] As described above, the embodiments of the present invention have been described. However, the above-described embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of the features described in the embodiments are essential means for solving the problems of the invention.

[0075] The present invention can be appropriately modified and implemented without departing from its gist. For example, in the above embodiment, the case where the member to be measured is the rack shaft 13 has been described. However, the present invention is also applicable to the detection of the stroke position of a member that strokes other than the rack shaft 13.

[0076] Also, in the above embodiment, the case where the rotor 2 is a gear has been described. However, the present invention is not limited to this, and a roller or the like that rotates due to friction with the member to be measured may also be used.

Explanation of Reference Numerals

[0077] 1, 1a… Stroke sensor 2… Rotating body 21… First rotating body 22… Second rotating body 3… Rotation detection unit 4… Stroke position detection unit 5… Support member 13… Rack shaft (member to be measured) 13a… Tooth portion 31… Rotating body side substrate 31a… Conductor pattern 32… Detection coil 33… Detection circuit 61… Magnet 62… Magnetic detection element 63… Detection circuit

Claims

1. A sensor for detecting the stroke position of a rod-shaped member to be measured that strokes in the axial direction, Two disk-shaped rotators that rotate as the member to be measured strokes, A rotation detector that detects the rotation of each of the two rotators, A stroke position detector that obtains the stroke position of the member to be measured based on the rotation of the two rotators detected by the rotation detector, and is provided with, At least one of the two rotators is provided in direct contact with the member to be measured, The two rotators are arranged side by side in an arrangement direction perpendicular to the axial direction of the member to be measured, and are provided so as to be adjacent to the member to be measured in the arrangement perpendicular direction perpendicular to the axial direction and the arrangement direction, And, when viewed from the axial direction, each of the two rotators is provided such that its rotation axis direction is inclined with respect to the arrangement direction, Stroke sensor.

2. The rotation detector is, Two rotator-side substrates that are integrally provided on the end faces in the rotation axis direction of the two rotators and each have a conductor pattern formed in a predetermined pattern along the circumferential direction of the rotator, Two detection coils that are respectively provided so as to face the two rotator-side substrates and are provided so as not to rotate as the rotator rotates, A detection circuit that detects the rotation angle of the corresponding rotator based on the change in the inductance of the detection coil when an AC voltage is applied to each detection coil, and has, The stroke sensor according to claim 1.

3. The two rotators are arranged such that their rotation axes are orthogonal to each other, The two detection coils are respectively arranged such that the magnetic field generation directions when the AC voltage is applied are orthogonal to each other, The stroke sensor according to claim 2.

4. The two rotators are configured such that the rotation angles when the member to be measured is stroked are different from each other, And, the conductor patterns formed on the rotator-side substrates provided on the two rotators are formed to have the same pattern configuration in the circumferential direction of the rotator, The stroke sensor according to claim 2 or 3.

5. The two rotators are configured such that the rotation angles when the member to be measured is stroked are the same, Moreover, the conductor patterns formed on the rotor-side substrates provided on the two rotors are formed so as to have different pattern configurations in the circumferential direction of the rotors. The stroke sensor according to claim 2 or 3.

6. The rotation detection unit Two magnets respectively provided integrally on the two rotors, Magnetic detection elements respectively provided so as not to rotate with the rotation of the rotor, and detecting magnetic fields from the two magnets, A detection circuit that detects the rotation angle of the corresponding rotor based on the detection result of the magnetic detection element. The stroke sensor according to claim 1.

7. The two rotors are arranged such that their rotation axes are orthogonal to each other, Two magnetic detection elements arranged such that the detection directions of the magnetic fields are orthogonal to each other, and detecting the magnetic fields of the corresponding magnets respectively. The stroke sensor according to claim 6.

8. The two rotors are arranged such that their rotation axes are orthogonal to each other, The magnetic detection element is configured to be able to detect magnetic fields in two directions orthogonal to each other, and detects the magnetic fields of the two magnets in the two directions respectively. The stroke sensor according to claim 6.

9. The two magnets have the same configuration, The two rotors are configured such that the rotation angles when the member to be measured is stroked are different from each other. The stroke sensor according to any one of claims 6 to 8.

10. The member to be measured has a tooth portion with teeth formed at equal intervals in the axial direction on at least a part of its outer peripheral surface, At least one of the two rotors is a gear that directly meshes with the tooth portion. The stroke sensor according to any one of claims 1 to 9.

11. Both of the two rotors are gears that directly mesh with the tooth portion. The stroke sensor according to claim 10.

12. One of the two rotors is a gear that directly meshes with the tooth portion, The other of the two rotors is a gear that directly meshes with one of the rotors. The stroke sensor according to claim 10.

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