Load detection device

Abstract

To provide a load detection device capable of improving detection accuracy. [Solution] The magnetic circuit 10 includes a magnetic flux generating unit 13, a first magnetostrictive material 11, and a second magnetostrictive material 12. The first transmission member 31 transmits a load applied from the outside of one side in the axial direction of the ring-shaped magnetic circuit 10 to the first magnetostrictive material 11 and the second magnetostrictive material 12. The second transmission member 32 transmits a load applied from the outside of the other side in the axial direction of the magnetic circuit 10 to the first magnetostrictive material 11 and the second magnetostrictive material 12. The magnetic detection element 20 is provided at a position facing the gap 14 or within the gap 14 and outputs a signal corresponding to the magnetic flux flowing through the magnetic circuit 10. The molded member integrally molds the magnetic flux generating unit 13, the first magnetostrictive material 11, the second magnetostrictive material 12, the first transmission member 31, and the second transmission member 32 in resin.

Description

Technical Field

[0001] The present invention relates to a load detection device using the magnetostrictive effect.

Background Art

[0002] Conventionally, a load detection device using the magnetostrictive effect has been known.

[0003] The load detection device described in Patent Document 1 includes a magnetic circuit in which a magnet, a magnetostrictive material, and a yoke are annularly configured so that magnetic flux flows, a load transmission member that transmits an externally applied load to the magnetostrictive material, and a magnetic detection element that outputs a signal corresponding to a change in the magnetic flux flowing through the magnetic circuit. In this load detection device, when an externally applied load is transmitted to the magnetostrictive material via the load transmission member, the magnetic permeability of the magnetostrictive material changes, and the amount of magnetic flux generated by the magnet passing through the magnetic circuit changes. Therefore, the load acting from the outside can be measured based on the output signal of the magnetic detection element. In Patent Document 1, the load transmission member is called a stress transmission member.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the load detection device described in Patent Document 1 does not specify how to fix each component that constitutes the magnetic circuit, etc. Therefore, if the positions of the components that constitute the magnetic circuit, such as the magnet, magnetostrictive material, and yoke, are misaligned, magnetic flux transmission will not occur correctly in the magnetic circuit, and variations will occur in the amount of magnetic flux flowing through the magnetic circuit among multiple load detection devices. Furthermore, if the positions of the load transmission member and the magnetostrictive material are misaligned, load transmission from the outside to the magnetostrictive material via the load transmission member will not occur correctly, and variations will occur in the change in the permeability of the magnetostrictive material in response to the externally applied load among multiple load detection devices. Consequently, the load detection device described in Patent Document 1 has the problem that variations occur in the values ​​detected by the magnetic detection element in response to the externally applied load among multiple devices, resulting in a deterioration of detection accuracy.

[0006] Furthermore, the load detection device described in Patent Document 1 has gaps or layers with lower relative permeability than the magnetostrictive material between the magnet and the magnetostrictive material, and between the magnetostrictive material and the yoke within the magnetic circuit. As a result, in this magnetic circuit, magnetic flux leakage increases at the gap-side end of the magnetostrictive material, the magnetic flux density distribution of the magnetostrictive material becomes larger, and low-density regions exist in the magnetostrictive material. Consequently, this load detection device has a problem in that the amount of change in magnetic flux density detected by the magnetic detection element in response to changes in the externally applied load (hereinafter referred to as "magnetic flux density gain ΔB") becomes small, and the detection accuracy deteriorates.

[0007] Furthermore, the load detection device described in Patent Document 1 is configured such that the load is applied only to the magnetostrictive material constituting the magnetic circuit, and no load is applied to the yoke. As a result, this load detection device has a problem in that the length of the magnetostrictive material in the magnetic circuit is relatively shorter by the length of the yoke, so the magnetic flux density gain ΔB becomes smaller and the detection accuracy deteriorates.

[0008] In view of the above points, the present invention aims to provide a load detection device capable of improving detection accuracy. [Means for solving the problem]

[0009] To achieve the above objective, according to the invention of claim 1, a load detection device for detecting an externally applied load is: A magnetic circuit (10) is configured in a ring shape such that the magnetic flux generated by the magnetic flux generating unit (13) generates magnetic flux, and a first magnetostrictive material (11) and a second magnetostrictive material (12) whose permeability changes according to an external force, and the magnetic flux generated by the magnetic flux generating unit flows in the order of the first magnetostrictive material, gap (14), second magnetostrictive material, and back to the magnetic flux generating unit. A first transmission member (31) transmits a load applied from the outside on one side in the direction in which the axis (CL) of the annular magnetic circuit extends to the first magnetostrictive material and the second magnetostrictive material, A second transmission member (32) transmits a load applied from the outside on the other side in the direction in which the axis extends to the first magnetostrictive material and the second magnetostrictive material, A magnetic detection element (20) is provided in a position opposite to or within the gap, and outputs a signal corresponding to the magnetic flux flowing through the magnetic circuit. The device comprises a magnetic flux generating section, a first magnetostrictive material, a second magnetostrictive material, a first transmission member, and a second transmission member, all integrally molded in resin by a molded member (50).

[0010] This prevents misalignment between the magnetic flux generating unit, the first magnetostrictive material, and the second magnetostrictive material, ensuring correct magnetic flux transmission in the magnetic circuit. Therefore, variations in the amount of magnetic flux flowing through the magnetic circuit are prevented between multiple load detection devices. Furthermore, because misalignment between the first and second magnetostrictive materials and the first and second transmission members is prevented, load transmission from the outside to the first and second magnetostrictive materials via the first or second transmission member is performed correctly. Consequently, variations in the change in permeability of the first and second magnetostrictive materials in response to externally applied loads are prevented between multiple load detection devices. Therefore, this load detection device prevents variations in the values ​​detected by the magnetic detection element in response to externally applied loads between multiple devices, thereby improving detection accuracy.

[0011] Furthermore, this load detection device does not require a gap between the magnetostrictive material and the yoke, or a layer with a lower relative permeability than the magnetostrictive material, as described in Patent Document 1, except for the gap where the magnetic detection element is provided. Therefore, it is possible to increase the magnetic flux density at the point where the load is transmitted from the first and second transmission members of the first and second magnetostrictive materials (hereinafter referred to as the "pressed portion"). Consequently, this load detection device can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0012] Furthermore, since this load detection device has a configuration in which the first and second transmission members transmit the load to both the first and second magnetostrictive material, it is possible to secure longer first and second pressed sections compared to a configuration with a yoke to which no load is applied, as described in Patent Document 1. Therefore, assuming the same area conditions as the device described in Patent Document 1, the width of the magnetic paths of the first and second pressed sections can be reduced, and the magnetic flux density of the first and second pressed sections can be increased accordingly. Consequently, this load detection device can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0013] Furthermore, since the magnetic circuit of this load detection device is configured in a ring shape so that the magnetic flux flows from the magnetic flux generation unit to the first magnetostrictive material, gap, second magnetostrictive material, and back to the magnetic flux generation unit, a gap can be provided at the position furthest from the magnetic flux generation unit, and the magnetic detection element can be placed there. Therefore, it is possible to ensure that the first and second pressed parts are long and to increase the magnetic flux density of the first and second pressed parts. Consequently, this load detection device can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0014] In this specification, "ring-shaped" is not limited to circular shapes, but includes various shapes such as elliptical, polygonal, and curved shapes, in which the magnetic path from the magnetic flux generated at the magnetic flux generating part to the magnetic flux generating part does not intersect along the way.

[0015] Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0016] <C000071>It is a perspective view of a load detection device according to the first embodiment. [Figure 2] It is a plan view of a load detection device according to the first embodiment. [Figure 3] It is a side view in the III direction of FIG. 2. <000,076> [Figure 4] It is a bottom view in the IV direction of FIG. 3. [Figure 5] It is an exploded perspective view of a load detection device according to the first embodiment. [Figure 6] It is a perspective view showing a magnetic circuit, a first transmission member, and a second transmission member included in the load detection device according to the first embodiment. [Figure 7A] It is a cross-sectional view taken along line VII-VII of FIG. 3 (i.e., the boundary between the first transmission member and the magnetic circuit). [Figure 7B] It is an enlarged view of part VIIB of FIG. 7A. [Figure 7C] It is an enlarged view of part VIIC of FIG. 7A. [Figure 7D] It is an enlarged view of part VIID of FIG. 7A. [Figure 8A] It is a cross-sectional view taken along line VIII-VIII of FIG. 7A. [Figure 8B] It is an enlarged view of part VIIIB of FIG. 8A. [Figure 8C] It is an enlarged view of part VIIIC of FIG. 8A. [Figure 9A] It is a cross-sectional view taken along line IX-IX of FIGS. 7A and 8A. [Figure 9B] It is an enlarged view of part IXB of FIG. 9A. a [Figure 9C] It is an enlarged view of part IXC of FIG. 9A. [Figure 10] ] It is a perspective view showing a magnetic circuit, a first transmission member, a second transmission member, and a mold part included in the load detection device according to the first embodiment. [Figure 11] This is a plan view showing the magnetic circuit, first transmission member, second transmission member, and molded part of the load detection device according to the first embodiment. [Figure 12] Figure 11 shows a cross-sectional view of the line XII-XII. [Figure 13] Figures 11 and 12 show cross-sectional views along line XIII-XIII. [Figure 14] Figures 12 and 13 are bottom views in the XIV direction. [Figure 15] This is a plan view showing the magnetic circuit, first transmission member, and molded portion of the load detection device according to the second embodiment. [Figure 16] This is a plan view showing the magnetic circuit, first transmission member, and molded part of the load detection device according to the third embodiment. [Figure 17] Figure 16 is a side view in the XVII direction. [Figure 18] This is a plan view showing the magnetic circuit, first transmission member, and molded part of the load detection device according to the fourth embodiment. [Figure 19] This is a plan view showing the magnetic circuit, first transmission member, and molded part of the load detection device according to the fifth embodiment. [Figure 20] Figure 19 is a side view in the XX direction. [Figure 21] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the sixth embodiment. [Figure 22] Figure 21 is a cross-sectional view of the line XXII-XXII. [Figure 23] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the seventh embodiment. [Figure 24] Figure 23 shows a cross-sectional view of the line XXIV-XXIV. [Figure 25] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the eighth embodiment. [Figure 26]Figure 25 shows a cross-sectional view of the line XXVI-XXVI. [Figure 27] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the ninth embodiment. [Figure 28] Figure 27 shows a cross-sectional view along the line XXVIII-XXVIII. [Figure 29] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the 10th embodiment. [Figure 30] This is a cross-sectional view along the line XXX-XXX in Figure 29. [Figure 31] This is a cross-sectional view along the X-plane showing a magnetic circuit, a first transmission member, a second transmission member, and a magnetic detection element in a load detection device according to the 11th embodiment. [Figure 32] This is a cross-sectional view of the line XXXII-XXXII in Figure 31. [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals, and their descriptions are omitted.

[0018] (First Embodiment) The first embodiment will be described with reference to Figures 1 to 14. The load detection device 1 of the first embodiment is a load sensor that detects an externally applied load using the inverse magnetostrictive effect.

[0019] As shown in Figures 5 to 9A, the load detection device 1 includes a magnetic circuit 10, a magnetic detection element 20, a first transmission member 31, a second transmission member 32, a magnetic shield 40, a molded member 50, and the like.

[0020] As shown in Figures 6 and 7A, the magnetic circuit 10 includes a magnet 13 as a magnetic flux generating part, and a first magnetostrictive material 11 and a second magnetostrictive material 12 through which the magnetic flux generated by the magnet 13 passes. The magnet 13 is a permanent magnet that generates magnetic flux and is made of, for example, a samarium-cobalt magnet, a neodymium magnet, or the like.

[0021] The first magnetostrictive material 11 and the second magnetostrictive material 12 are made of a magnetic material whose permeability changes in response to an external force. The first magnetostrictive material 11 and the second magnetostrictive material 12 are made of, for example, electromagnetic stainless steel. The first magnetostrictive material 11 and the second magnetostrictive material 12 are each formed in a substantially arc shape.

[0022] One end of the first magnetostrictive material 11 is connected to the north pole side of the magnet 13, and one end of the second magnetostrictive material 12 is connected to the south pole side of the magnet 13. A gap 14 is provided between the other end of the first magnetostrictive material 11 (i.e., the end of the first magnetostrictive material 11 opposite to the magnet 13) and the other end of the second magnetostrictive material 12 (i.e., the end of the second magnetostrictive material 12 opposite to the magnet 13). The magnetic circuit 10 is configured in a ring shape so that the magnetic flux generated by the magnet 13 flows in the order of north pole of the magnet 13, first magnetostrictive material 11, gap 14, second magnetostrictive material 12, and south pole of the magnet 13.

[0023] In this specification, "ring-shaped" is not limited to circular shapes, but includes various shapes such as elliptical, polygonal, and curved shapes, in which the magnetic path from the magnetic flux generated by the magnet 13 through each component to the magnet 13 does not intersect along the way.

[0024] In the following explanation, the direction in which the axis CL of the magnetic circuit 10 extends is referred to as the "axial direction." The circumferential direction of a virtual circle perpendicular to the axis CL of the magnetic circuit 10 and centered on the axis CL is simply referred to as the "circumferential direction." The radial direction of that virtual circle is simply referred to as the "radial direction," with the side of the virtual circle farther from the axis CL being called the "radial outer side" and the side closer to the axis CL being called the "radial inner side." Furthermore, the first magnetostrictive material 11 and the second magnetostrictive material 12 are sometimes collectively referred to as "sensor magnetostrictive materials 11 and 12".

[0025] As shown in Figures 5 and 8A, the magnetic detection element 20 is mounted on the substrate 21 and provided on the gap 14 side of the magnetic circuit 10. The magnetic detection element 20 is provided at a position facing the gap 14 in the axial direction (i.e., a position facing the gap 14 in the axial direction) and outputs an electrical signal corresponding to the magnetic flux flowing through the magnetic circuit 10. The magnetic detection element 20 may also be provided at a position facing the gap 14 on one or the other side in the axial direction. The electrical signal output by the magnetic detection element 20 is output to the outside from terminal 22. The magnetic detection element 20 is composed of, for example, a TMR-IC or a Hall IC, and may or may not have a substrate 21. TMR stands for Tunnel Magneto Resistance. IC stands for Integrated Circuit. The substrate 21 is sealed with potting material 23.

[0026] As shown in Figures 6, 8A, and 9A, the first transmission member 31 is provided on one side in the axial direction relative to the sensor magnetostrictive materials 11 and 12. The first transmission member 31 is a load transmission member that transmits a load applied from the outside on one side in the axial direction to the sensor magnetostrictive materials 11 and 12. The second transmission member 32 is provided on the other side in the axial direction relative to the sensor magnetostrictive materials 11 and 12. The second transmission member 32 is a load transmission member that transmits a load applied from the outside on the other side in the axial direction to the sensor magnetostrictive materials 11 and 12. The first transmission member 31 and the second transmission member 32 are formed from non-magnetic materials such as SUS316L, SUSXM7, SUH660, A6061, and ADC12.

[0027] The first transmission member 31 and the second transmission member 32 transmit the load applied from the outside to a portion of the sensor magnetostrictive materials 11 and 12. In the following description, the portion of the first magnetostrictive material 11 to which the load is transmitted from the first transmission member 31 and the second transmission member 32 (i.e., the portion of the first magnetostrictive material 11 that is in contact with the first transmission member 31 and the second transmission member 32) is referred to as the first pressed portion 15. The portion of the second magnetostrictive material 12 to which the load is transmitted from the first transmission member 31 and the second transmission member 32 (i.e., the portion of the second magnetostrictive material 12 that is in contact with the first transmission member 31 and the second transmission member 32) is referred to as the second pressed portion 16. In Figure 7A, the first pressed portion 15 and the second pressed portion 16 are shown with dashed hatching, although this is not a cross-section. The second transmission member 32 presses the first pressed portion 15 and the second pressed portion 16 against the first transmission member 31 from the other side in the axial direction.

[0028] The radial width of the first transmission member 31 and the second transmission member 32 is greater than or equal to the width of the first pressed portion 15 and the second pressed portion 16. The first transmission member 31 and the second transmission member 32 press over the entire radial width range of the first pressed portion 15 and the second pressed portion 16. In addition, the first transmission member 31 and the second transmission member 32 press over the first pressed portion 15 and the second pressed portion 16, but do not press over the end of the first magnetostrictive material 11 on the gap 14 side or the end of the second magnetostrictive material 12 on the gap 14 side.

[0029] In the following explanation, the side of the first transmission member 31 opposite to the sensor magnetostrictive materials 11 and 12 will be referred to as the "interface surface 34 of the first transmission member 31". Similarly, the side of the second transmission member 32 opposite to the sensor magnetostrictive materials 11 and 12 will be referred to as the "interface surface 36 of the second transmission member 32".

[0030] In the following description, the line connecting the center of the magnet 13 and the axis CL, and the plane containing the axis CL, are referred to as the X-plane, and the plane perpendicular to the X-plane and containing the axis CL is referred to as the Y-plane. In the first embodiment, the interface surface 34 of the first transmission member 31 and the interface surface 36 of the second transmission member 32 are symmetrical with respect to the X-plane.

[0031] Furthermore, as shown in Figure 7A, in the first embodiment, the first pressed portion 15 and the second pressed portion 16 are symmetrical with respect to the X-plane. In addition, in the first embodiment, the first magnetostrictive material 11 and the second magnetostrictive material 12 are symmetrical with respect to the X-plane.

[0032] Furthermore, the first pressed portion 15 and the second pressed portion 16 have a shape in which the radial width gradually changes from the magnet 13 towards the gap 14. Specifically, the first pressed portion 15 and the second pressed portion 16 have a shape in which the radial width gradually decreases from the magnet 13 side towards the gap 14 side. Also, the first magnetostrictive material 11 has a shape in which the radial width gradually increases from the part of the first pressed portion 15 opposite to the magnet 13 towards the end on the gap 14 side. Similarly, the second magnetostrictive material 12 also has a shape in which the radial width gradually increases from the part of the second pressed portion 16 opposite to the magnet 13 towards the end on the gap 14 side. Therefore, the first pressed portion 15 is the part of the first magnetostrictive material 11 where the magnetic flux density is greater than that of the end on the gap 14 side. In other words, the first pressed portion 15 is a portion within the first magnetostrictive material 11 where the change in permeability in response to the application of a load is greater than that at the end on the gap 14 side. Similarly, the second pressed portion 16 is a portion within the second magnetostrictive material 12 where the magnetic flux density is greater than that at the end on the gap 14 side. In other words, the second pressed portion 16 is also a portion within the second magnetostrictive material 12 where the change in permeability in response to the application of a load is greater than that at the end on the gap 14 side.

[0033] Here, the detection accuracy of the magnetic detection element 20 is expressed by the following equation 1. Detection accuracy = {(Sensitivity drift / 100) × B0 + Offset} / ΔB ... (Equation 1) B0 is the magnetic flux density detected by the magnetic detection element 20 when no load is applied to the first transmission member 31 and the second transmission member 32 from the outside (hereinafter referred to as "no-load magnetic flux density B0"). ΔB is the amount of change in magnetic flux density that the magnetic detection element 20 detects in response to a change in the load applied from the outside (hereinafter referred to as "magnetic flux density gain ΔB").

[0034] According to Equation 1 above, the larger the magnetic flux density gain ΔB and the smaller the no-load magnetic flux density B0, the better the detection accuracy of the magnetic detection element 20. In the load detection device 1 of the first embodiment, the magnetic flux density gain ΔB can be increased and the detection accuracy improved by setting the magnetic flux density of the first pressed portion 15 and the second pressed portion 16 of the sensor magnetostrictive materials 11 and 12 to an appropriate range with a large magnetostrictive coefficient (for example, a range near 1T).

[0035] As shown in Figures 1 to 5 and Figures 7A to 9A, the magnetic shield 40 is a housing formed from a magnetic material that covers the first transmission member 31, part of the second transmission member 32, the magnetic circuit 10, the magnetic detection element 20, and the molded member 50. In the following description, the magnetic circuit 10, the first transmission member 31, the second transmission member 32, the magnetic detection element 20, and the molded member 50 are collectively referred to as the internal structure.

[0036] The magnetic shield 40 is formed from, for example, electromagnetic pure iron such as SUY-0 equivalent to JISC2504. Preferably, the magnetic shield 40 is made of a material with a maximum magnetic permeability of 10,000 or more. That is, the magnetic permeability of the material used for the magnetic shield 40 is higher than that of general-purpose steel. This makes it possible to suppress the influence of the magnetic field generated by a magnetic foreign object (for example, general-purpose steel) when it approaches the load detection device 1 from the outside. Furthermore, it is possible to suppress magnetic flux leakage from the magnetic circuit 10 to the outside.

[0037] The magnetic shield 40 has an outer cylinder portion 43, an inner cylinder portion 44, a top plate portion 45, and a bottom plate portion 46. The outer cylinder portion 43 is formed in a cylindrical shape with an axis extending parallel to the axis CL of the magnetic circuit 10 and is provided radially outward relative to the internal structure. The inner cylinder portion 44 is formed in a cylindrical shape with an axis extending parallel to the axis CL of the magnetic circuit 10 and is provided radially inward relative to the internal structure. The top plate portion 45 is provided on one side in the axial direction of the internal structure. The bottom plate portion 46 is provided on the other side in the axial direction of the internal structure. In this specification, "cylindrical" is not limited to cylindrical shapes, but includes, for example, rectangular cylinders, elliptical shapes, etc.

[0038] The magnetic shield 40 of the first embodiment is composed of two parts. Specifically, the outer cylinder portion 43, the inner cylinder portion 44, and the bottom plate portion 46 are composed of the first shield member 41, and the top plate portion 45 is composed of the second shield member 42. As shown in Figures 1, 2, and 5, the first shield member 41 has a plurality of claw portions 47 that protrude from the outer edge on one side in the axial direction of the outer cylinder portion 43. These plurality of claw portions 47 are bent and the outer edge of the second shield member 42 (i.e., the top plate portion 45) is crimped and fixed.

[0039] The top plate portion 45 has a first insertion hole 48 through which the interface surface 34 side end of the first transmission member 31 is inserted. Therefore, the interface surface 34 side end of the first transmission member 31 protrudes to the outside from the magnetic shield 40 through the first insertion hole 48. Also, as shown in Figure 4, the bottom plate portion 46 also has a second insertion hole 49 through which the interface surface 36 side end of the second transmission member 32 is inserted. Therefore, the interface surface 36 side end of the second transmission member 32 also protrudes to the outside from the magnetic shield 40 through the second insertion hole 49. As a result, load transmission occurs between the first transmission member 31, the sensor magnetostrictive materials 11 and 12, and the second transmission member 32 without passing through the magnetic shield 40. Therefore, loads applied from the outside to the interface surface 34 of the first transmission member 31 or the interface surface 36 of the second transmission member 32 are transmitted to the sensor magnetostrictive materials 11 and 12 via only the first transmission member 31 or the second transmission member 32, without passing through the magnetic shield 40. Consequently, loads applied from the outside can be applied perpendicularly (i.e., parallel to the axis CL) to the first pressed portion 15 and the second pressed portion 16 of the sensor magnetostrictive materials 11 and 12, without being affected by the shape or rigidity of the magnetic shield 40. As a result, the change in the magnetic permeability of the sensor magnetostrictive materials 11 and 12 in response to the external force becomes stable, and detection accuracy can be improved.

[0040] As shown in Figures 5, 8A, and 9A, the gaps between the first insertion hole 48 and the first transmission member 31, the gap between the second insertion hole 49 and the second transmission member 32, and the gap between the first shield member 41 and the second shield member 42 are sealed with a sealing material 60. As the sealing material 60, for example, a silicone-based moisture-curing liquid gasket (FIPG: Formed In Place Gasket) is used.

[0041] As shown in Figures 5 and 7A to 9A, the molded member 50 is installed inside the magnetic shield 40. The molded member 50 is made by integrally resin-molding the magnetic circuit 10, the first transmission member 31, the second transmission member 32, and the terminal 22, excluding the magnetic detection element 20 and the substrate 21. Figures 10 to 14 show the state of the molded member 50 before it is installed inside the magnetic shield 40, with the magnetic circuit 10, the first transmission member 31, the second transmission member 32, and the terminal 22 integrally resin-molded.

[0042] The molded member 50 is formed from a fiber-reinforced resin, such as a resin material like polyphenylene sulfide (PPS) resin, epoxy resin, or phenolic resin, which is compounded with glass fibers or the like. By increasing the specific strength of the molded member 50 in this way, it becomes possible to firmly fix the positions of the magnetic circuit 10, the first transmission member 31, and the second transmission member 32.

[0043] The difference between the linear expansion coefficient of the molded member 50 and the linear expansion coefficients of the sensor magnetostrictive materials 11 and 12 is preferably 15 ppm / °C or less. For example, if the linear expansion coefficient of the sensor magnetostrictive materials 11 and 12 is 10 ppm / °C, the linear expansion coefficient of the molded member 50 is preferably 15 to 25 ppm / °C or less. By making the linear expansion coefficients of the molded member 50 and the sensor magnetostrictive materials 11 and 12 approximately the same (i.e., 15 ppm / °C or less), the thermal stress acting from the molded member 50 to the sensor magnetostrictive materials 11 and 12 can be reduced even when both the molded member 50 and the sensor magnetostrictive materials 11 and 12 expand or contract due to temperature changes.

[0044] The molded member 50 is formed by injection molding. Hereinafter, the resin flow direction formed during the injection molding of the molded member 50 will be referred to as the "resin flow direction MD," and the direction perpendicular to the resin flow direction formed during the injection molding of the molded member 50 will be referred to as the "resin flow perpendicular direction TD." Note that MD is an abbreviation for Machine Direction, and TD is an abbreviation for Transverse Direction.

[0045] For the molded member 50, the difference between the coefficient of linear expansion in the resin flow direction MD and the coefficient of linear expansion in the resin flow perpendicular direction TD is preferably 15 ppm / °C or less. By making the coefficient of linear expansion in the resin flow direction MD and the coefficient of linear expansion in the resin flow perpendicular direction TD approximately the same (i.e., 15 ppm / °C or less), even if there is variation in the orientation of glass fibers, etc., within the resin in the molded member 50, the variation in thermal stress acting on the sensor magnetostrictive materials 11 and 12 during temperature changes can be reduced.

[0046] The molded member 50 has an outer material-reducing portion 51 on the radially outer side relative to the sensor magnetostrictive materials 11 and 12. This allows the molded member 50 to have a thinner radial wall thickness at the location of the outer material-reducing portion 51 where it contacts the radially outer side of the sensor magnetostrictive materials 11 and 12 than the radial wall thickness at the other locations. The molded member 50 also has an inner material-reducing portion 52 on the radially inner side relative to the sensor magnetostrictive materials 11 and 12. This allows the molded member 50 to have a thinner radial wall thickness at the location of the inner material-reducing portion 52 where it contacts the radially inner side of the sensor magnetostrictive materials 11 and 12 than the radial wall thickness at the other locations. Therefore, even if the molded member expands or contracts due to temperature changes, the thermal stress acting from the molded member 50 on the sensor magnetostrictive materials 11 and 12 can be reduced.

[0047] Furthermore, the outer material removal portion 51 is not provided on the axial portion of the multiple claw portions 47; instead, a columnar portion 53 of the molded member 50 is provided. This prevents deformation of the second shield member 42 (i.e., the top plate portion 45) and the molded member 50 when the multiple claw portions 47 are bent.

[0048] As shown in Figures 1, 2, 9A to 11, and 13, a first projection 54 is provided on the surface of the molded member 50 facing the axial top plate portion 45. Furthermore, a first fitting hole 401 is provided in the top plate portion 45 of the magnetic shield 40 at a position corresponding to the first projection 54. On the other hand, as shown in Figures 4, 9A, 13, and 14, a second projection 55 is provided on the surface of the molded member 50 facing the axial bottom plate portion 46. Furthermore, a second fitting hole 402 is provided in the bottom plate portion 46 of the magnetic shield 40 at a position corresponding to the second projection 55.

[0049] The first projection 54 of the molded member 50 engages with the first fitting hole 401 of the magnetic shield 40, and the second projection 55 of the molded member 50 engages with the second fitting hole 402 of the magnetic shield 40, thereby preventing radial and circumferential misalignment between the molded member 50 and the magnetic shield 40. In other words, the first projection 54 and the first fitting hole 401, and the second projection 55 and the second fitting hole 402 constitute a "positioning section" that positions the molded member 50 and the magnetic shield 40. Furthermore, one of the two first fitting holes 401 provided in the top plate portion 45 of the magnetic shield 40 is an elongated hole. Also, one of the two second fitting holes 402 provided in the bottom plate portion 46 of the magnetic shield 40 is an elongated hole.

[0050] As shown in Figures 7B, 7C, 8B, and 9B, a gap S1 is provided between the radially outward-facing surface 56 of the molded member 50 and the radially inward-facing surface 403 of the magnetic shield 40. More specifically, this gap S1 is provided between all radially outward-facing surfaces 56 of the molded member 50 and all radially inward-facing surfaces 403 of the magnetic shield 40. Also, as shown in Figures 7D, 8C, and 9C, a gap S2 is provided between the radially inward-facing surface 57 of the molded member 50 and the radially outward-facing surface 404 of the magnetic shield 40. More specifically, this gap S2 is also provided between all radially inward-facing surfaces 57 of the molded member 50 and all radially outward-facing surfaces 404 of the magnetic shield 40. The radial widths of these gaps S1 and S2 are set to be large enough that the molded member 50 and the magnetic shield 40 are not constrained by each other, even if the molded member 50 and the magnetic shield 40 expand or contract due to temperature changes. Specifically, the radial widths of these gaps S1 and S2 are set to, for example, about 10 μm to several mm.

[0051] An example of a manufacturing method for the load detection device 1 described above will be explained. First, the magnet 13, the first magnetostrictive material 11, the second magnetostrictive material 12, the first transmission member 31, the second transmission member 32, and the terminal 22 are placed in a mold (not shown), and molten resin is injected into the mold. This forms a molded member 50 (i.e., a sub-assembly) in which these components are integrally molded in resin. Next, the substrate 21 on which the magnetic detection element 20 is mounted is fixed to the molded member 50 with adhesive or the like, and the substrate 21 is sealed with potting material 23. Subsequently, the internal structure integrated by the molded member 50 is inserted into the first shield member 41, and the molded member 50, the first shield member 41, and the second shield member 42 are positioned. After that, the first shield member 41 and the second shield member 42 are crimped and fixed. Finally, the sealant 60 is applied to the gap between the first insertion hole 48 and the first transmission member 31, the gap between the second insertion hole 49 and the second transmission member 32, and the gap between the first shield member 41 and the second shield member 42, etc., and the load detection device 1 is completed.

[0052] (Effects of the first embodiment) The load detection device 1 of the first embodiment described above provides the following effects.

[0053] (1) In the first embodiment, the magnetic circuit 10 is configured in an annular shape so that the magnetic flux generated by the magnet 13 flows in the order of magnet 13 to the first magnetostrictive material 11, gap 14, second magnetostrictive material 12, and magnet 13. The first transmission member 31 and the second transmission member 32 transmit the load applied from the outside to the sensor magnetostrictive materials 11 and 12. The magnetic detection element 20 is provided at a position opposite the gap 14 in the axial direction and outputs an electrical signal corresponding to the magnetic flux flowing through the magnetic circuit 10. The molded member 50 integrally resin-moldes the magnet 13, sensor magnetostrictive materials 11 and 12, first transmission member 31, and second transmission member 32.

[0054] According to this, misalignment between the magnet 13 and the sensor magnetostrictive materials 11 and 12 is prevented, so that magnetic flux transmission in the magnetic circuit 10 is performed correctly. Therefore, variations in the amount of magnetic flux flowing through the magnetic circuit 10 are prevented between multiple load detection devices 1. In addition, misalignment between the magnetic circuit 10 and the first transmission member 31 and the second transmission member 32 is prevented, so that load transmission from the outside to the sensor magnetostrictive materials 11 and 12 via the first transmission member 31 and the second transmission member 32 is performed correctly. Therefore, variations in the change in the permeability of the sensor magnetostrictive materials 11 and 12 in response to the externally applied load are prevented between multiple load detection devices 1. Consequently, this load detection device 1 can prevent variations in the values ​​detected by the magnetic detection element 20 in response to the externally applied load between multiple devices, thereby improving detection accuracy.

[0055] Furthermore, this load detection device 1 does not require a gap between the magnetostrictive material and the yoke, or a layer with a lower relative permeability than the magnetostrictive material, to be provided in the middle of the magnetic circuit, except for the gap 14 where the magnetic detection element 20 is provided, as described in Patent Document 1. Therefore, it is possible to increase the magnetic flux density of the first pressed portion 15 and the second pressed portion 16. Consequently, this load detection device 1 can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0056] Furthermore, since the load detection device 1 is configured such that the first transmission member 31 and the second transmission member 32 transmit the load to both the first magnetostrictive material 11 and the second magnetostrictive material 12, the first pressed portion 15 and the second pressed portion 16 can be made longer compared to a configuration with a yoke to which no load is applied, as described in Patent Document 1. Therefore, assuming the same area conditions as the device described in Patent Document 1, the width of the magnetic paths of the first pressed portion 15 and the second pressed portion 16 can be reduced, and the magnetic flux density of the first pressed portion 15 and the second pressed portion 16 can be increased accordingly. Consequently, the load detection device 1 can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0057] Furthermore, in this load detection device 1, the magnetic circuit 10 is configured in a ring shape so that the magnetic flux flows in the order of magnet 13, first magnetostrictive material 11, gap 14, second magnetostrictive material 12, and magnet 13. Therefore, a gap 14 can be provided at the position furthest from the magnet 13, and the magnetic detection element 20 can be placed there. As a result, the first pressed portion 15 and the second pressed portion 16 can be made longer, and the magnetic flux density of the first pressed portion 15 and the second pressed portion 16 can be increased. Consequently, this load detection device 1 can increase the magnetic flux density gain ΔB and improve detection accuracy.

[0058] (2) In the first embodiment, the molded member 50 is formed by integrally molding the magnetic circuit 10, the first transmission member 31 and the second transmission member 32 in resin, excluding the magnetic detection element 20. According to this, since the molded member 50 does not resin-molde the magnetic detection element 20, even if the molded member 50, magnetic circuit 10, first transmission member 31, and second transmission member 32 expand or contract due to temperature changes, thermal stress does not act on the magnetic detection element 20. Therefore, detection accuracy can be improved.

[0059] (3) In the first embodiment, the molded member 50 has an outer material removal portion 51 on the radially outer side relative to the sensor magnetostrictive materials 11 and 12. The molded member 50 also has an inner material removal portion 52 on the radially inner side relative to the sensor magnetostrictive materials 11 and 12. According to this, the mold member 50 can have a radial thickness at the locations of the outer material removal portion 51 and the inner material removal portion 52 that are in contact with the sensor magnetostrictive materials 11 and 12, which is thinner than the radial thickness at locations other than the outer material removal portion 51 and the inner material removal portion 52. Therefore, even if the mold member 50 expands or contracts due to temperature changes, the thermal stress acting from the mold member 50 on the sensor magnetostrictive materials 11 and 12 can be reduced. Consequently, this load detection device 1 can suppress changes in the magnetic permeability of the sensor magnetostrictive materials 11 and 12 due to temperature changes and improve detection accuracy.

[0060] (4) In the first embodiment, a gap S1 is provided between the radially outward-facing surface 56 of the molded member 50 and the magnetic shield 40, and a gap S2 is provided between the radially inward-facing surface 57 of the molded member 50 and the magnetic shield 40. According to this, even if the magnetic shield 40 expands or contracts due to temperature changes, it is possible to prevent thermal stress from acting on the sensor magnetostrictive materials 11 and 12 via the molded member 50 from the magnetic shield 40. Therefore, this load detection device 1 can suppress changes in the magnetic permeability of the sensor magnetostrictive materials 11 and 12 due to temperature changes and improve detection accuracy.

[0061] (5) In the first embodiment, the gaps S1 and S2 between the magnetic shield 40 and the molded member 50 are provided between all radially outward-facing surfaces 56 of the molded member 50 and the magnetic shield 40, and between all radially inward-facing surfaces 57 of the molded member 50 and the magnetic shield 40. According to this, even if the magnetic shield 40 expands or contracts due to temperature changes, it is possible to reliably prevent thermal stress from acting on the sensor magnetostrictive materials 11 and 12 via the molded member 50 from the magnetic shield 40. Therefore, this load detection device 1 can suppress changes in the magnetic permeability of the sensor magnetostrictive materials 11 and 12 due to temperature changes and improve detection accuracy.

[0062] (6) In the first embodiment, the surface of the molded member 50 facing the axial top plate portion 45 and the top plate portion 45 are provided with a first projection 54 and a first fitting hole 401 as positioning parts. In addition, the surface of the molded member 50 facing the axial bottom plate portion 46 and the bottom plate portion 46 are provided with a second projection 55 and a second fitting hole 402 as positioning parts. According to this, misalignment between the molded member 50 and the magnetic shield 40 is prevented. As a result, a gap S1 can be provided between all surfaces 56 of the molded member 50 facing radially outward and the magnetic shield 40, and a gap S2 can be provided between all surfaces 57 of the molded member 50 facing radially inward and the magnetic shield 40.

[0063] (7) In the first embodiment, the difference between the coefficient of thermal expansion of the molded member 50 and the coefficient of thermal expansion of the sensor magnetostrictive materials 11 and 12 is 15 ppm / °C or less. According to this, it is possible to make the linear expansion coefficient of the mold member 50 and the linear expansion coefficient of the sensor magnetostrictive materials 11 and 12 approximately the same (i.e., 15 ppm / °C or less). Therefore, even if both the mold member 50 and the sensor magnetostrictive materials 11 and 12 expand or contract due to temperature changes, the thermal stress acting from the mold member 50 on the sensor magnetostrictive materials 11 and 12 is reduced. Consequently, this load detection device 1 can suppress changes in the magnetic permeability of the sensor magnetostrictive materials 11 and 12 due to temperature changes and improve detection accuracy.

[0064] (8) In the first embodiment, the difference between the coefficient of thermal expansion in the resin flow direction MD and the coefficient of thermal expansion in the resin flow perpendicular direction TD in the molded member 50 is 15 ppm / °C or less. According to this, if the difference between the linear expansion coefficient in the resin flow direction MD and the linear expansion coefficient in the resin flow perpendicular direction TD is large in the molded member 50, the variation in the orientation of glass fibers, etc., within the molded resin surrounding the sensor magnetostrictive materials 11 and 12 will increase, leading to greater variation in the thermal stress acting on the sensor magnetostrictive materials 11 and 12 during temperature changes. Consequently, the variation in temperature characteristics between individual load detection devices 1 will also increase. In contrast, in the first embodiment, the difference between the coefficient of linear expansion in the resin flow direction MD and the coefficient of linear expansion in the resin flow perpendicular direction TD is set to be approximately the same (i.e., 15 ppm / °C or less). This reduces the variation in thermal stress acting on the sensor magnetostrictive materials 11 and 12 during temperature changes, even if there is variation in the orientation of glass fibers and the like within the resin in the molded member 50. Therefore, it is possible to reduce the variation in temperature characteristics between individual load detection devices 1.

[0065] (9) In the first embodiment, the mold member 50 is formed of a material containing glass fibers in the resin. According to this, by increasing the specific strength of the molded member 50, the positions of the magnetic circuit 10, the first transmission member 31, and the second transmission member 32 can be firmly determined. As a result, magnetic flux transmission in the magnetic circuit 10 is performed correctly, preventing variations in the amount of magnetic flux flowing through the magnetic circuit 10 among multiple load detection devices 1. Furthermore, since load transmission from the outside to the sensor magnetostrictive materials 11 and 12 via the first transmission member 31 and the second transmission member 32 is performed correctly, variations in the change in the permeability of the sensor magnetostrictive materials 11 and 12 in response to the externally applied load are prevented among multiple load detection devices 1. Therefore, this load detection device 1 can prevent variations in the values ​​detected by the magnetic detection element 20 in response to the externally applied load among multiple devices, thereby improving detection accuracy.

[0066] (Second to fifth embodiments) The second to fifth embodiments will now be described. The second embodiment is the same as the first embodiment except that the gate position during injection molding of the mold member 50 is changed. Therefore, only the parts that differ from the first embodiment will be described.

[0067] (Second Embodiment) As shown in Figure 15, in the second embodiment, the gate marks 58 and 59, which are the marks left by the molten resin injected from the gate into a mold (not shown) during resin injection molding of the mold member 50, are arranged symmetrically in the X-plane. In the following description, one of the two gate marks will be referred to as the "first gate mark 58" and the other gate mark as the "second gate mark 59".

[0068] In Figure 15, θ1 is defined as the angle between the line segment connecting the first gate mark 58 and the axis CL and the X-plane, and θ2 is defined as the angle between the line segment connecting the second gate mark 59 and the axis CL and the X-plane. In this case, θ1 and θ2 are the same angle. Also, the distance D1 between the first gate mark 58 and the axis CL and the distance D2 between the second gate mark 59 and the axis CL are the same. That is, the first gate mark 58 and the second gate mark 59 are arranged symmetrically in the X-plane. Note that θ1 and θ2 are not limited to 90° and can be any angle.

[0069] In the second embodiment described above, when the mold member 50 is injection-molded, the molten resin injected from the positions of the first gate mark 58 and the second gate mark 59 flows symmetrically within the mold with respect to the X-plane, so that the orientation of glass fibers and the like within the resin is symmetrical with respect to the X-plane. Therefore, when the mold member 50 expands or contracts due to temperature changes, it is possible to equalize the thermal stress acting from the mold member 50 on the first magnetostrictive material 11 and the second magnetostrictive material 12. Thus, variations in temperature characteristics among multiple load detection devices 1 can be prevented, and detection accuracy can be improved.

[0070] (Third embodiment) As shown in Figures 16 and 17, in the third embodiment as well, the first gate mark 58 and the second gate mark 59 are arranged symmetrically in the X-plane. In Figure 16, the position where the first gate mark 58 is provided on the radially outward-facing surface of the mold member 50 is indicated by arrow 58a, and the position where the second gate mark 59 is provided is indicated by arrow 59a. Figure 17 shows the second gate mark 59.

[0071] The third embodiment described above can also achieve the same effects as the second embodiment.

[0072] (Fourth Embodiment) As shown in Figure 18, in the fourth embodiment, one gate mark 501 is located on the X-plane. In this configuration as well, when the mold member 50 is resin injection molded, the molten resin injected from the position of the gate mark 501 flows symmetrically within the mold with respect to the X-plane, so the orientation of glass fibers and the like within the resin is symmetrical with respect to the X-plane. Therefore, when the mold member 50 expands or contracts due to temperature changes, it is possible to equalize the thermal stress acting from the mold member 50 on the first magnetostrictive material 11 and the second magnetostrictive material 12. Thus, variations in temperature characteristics among multiple load detection devices 1 can be prevented, and detection accuracy can be improved.

[0073] (Fifth embodiment) As shown in Figures 19 and 20, in the fifth embodiment as well, one gate mark 501 is located on the X-plane. In Figure 19, the position where the gate mark 501 is provided on the radially outward-facing surface of the mold member 50 is indicated by arrow 501a.

[0074] The fifth embodiment described above can also achieve the same effects as the second to fourth embodiments.

[0075] (Sixth to eleventh embodiments) Embodiments 6 to 11 will now be described. Embodiments 6 to 11 are modified versions of Embodiment 1 by changing the configuration of the magnetic circuit 10 and the magnetic detection element 20, but otherwise have the same configuration as Embodiment 1 and others. In Figures 21 to 32, which are referenced in the description of Embodiments 6 to 11, the mold member 50 and the magnetic shield 40 are not shown. In the description of Embodiments 6 to 11, the left side of the paper in the figures is referred to as one side in the X direction, and the right side of the paper is referred to as the other side in the X direction.

[0076] (Sixth Embodiment) As shown in Figures 21 and 22, in the sixth embodiment, a magnet 13 is provided on one side in the X direction of the annular magnetic circuit 10, and a magnetic detection element 20 is provided on the other side in the X direction. That is, the magnetic circuit 10 of the sixth embodiment has substantially the same arrangement as that of the first embodiment. The magnetic detection element 20 is provided in a gap 14. In detail, the magnetic detection element 20 is provided in a gap 14 formed between the end 11a of the first magnetostrictive material 11 opposite to the magnet 13 and the end 12a of the second magnetostrictive material 12 opposite to the magnet 13. The magnetic detection element 20 is capable of outputting a signal corresponding to the magnetic flux flowing through the magnetic circuit 10.

[0077] (Seventh Embodiment) As shown in Figures 23 and 24, in the seventh embodiment, the annular magnetic circuit 10 is formed in a substantially rectangular shape when viewed from the axis CL side. In the annular magnetic circuit 10, a magnet 13 is provided on one side in the X direction, and a magnetic detection element 20 is provided on the other side in the X direction. The magnetic detection element 20 is provided in a gap 14. In detail, the magnetic detection element 20 is provided in a gap 14 formed between the end 11a of the first magnetostrictive material 11 opposite to the magnet 13 and the end 12a of the second magnetostrictive material 12 opposite to the magnet 13. The magnetic detection element 20 is capable of outputting a signal corresponding to the magnetic flux flowing through the magnetic circuit 10.

[0078] (Eighth embodiment) As shown in Figures 25 and 26, in the eighth embodiment, the magnetic detection element 20 is mounted offset to one side in the axial direction relative to the sensor magnetostrictive materials 11 and 12. The arrangement of the magnetic circuit 10 and the magnetic detection element 20 in the eighth embodiment is substantially the same as in the sixth embodiment. In this configuration as well, the magnetic detection element 20 is capable of outputting a signal corresponding to the magnetic flux flowing through the magnetic circuit 10.

[0079] (Ninth Embodiment) As shown in Figures 27 and 28, in the ninth embodiment, the magnet 13 and the magnetic detection element 20 are arranged side by side on one side in the X direction in an annular magnetic circuit 10. The magnetostrictive material 100 is continuously formed in an annular shape except where the magnetic detection element 20 is provided. The magnetic circuit 10 is configured in an annular shape so that the magnetic flux generated by the magnet 13 flows in the order of the N pole of the magnet 13, through the magnetostrictive material 100, and then through the S pole of the magnet 13. The magnetic detection element 20 outputs a signal corresponding to the magnetic flux passing through the gap provided between one end 100a of the magnetostrictive material 100 and the magnet 13.

[0080] (Tenth embodiment) As shown in Figures 29 and 30, the tenth embodiment is an annular magnetic circuit 10 in which a magnet 13 is provided on one side in the X direction and a magnetic detection element 20 is provided on the other side in the X direction. The magnetic detection element 20 is provided at a position facing the gap 14 (i.e., a position opposite the gap 14). In detail, the magnetic detection element 20 is provided at a position facing the gap 14 on the side closer to the axis CL of the gap 14. The magnetic detection element 20 is capable of outputting a signal corresponding to the magnetic flux flowing through the magnetic circuit 10.

[0081] (11th embodiment) As shown in Figures 31 and 32, the 11th embodiment is an annular magnetic circuit 10 in which a magnet 13 is provided on one side in the X direction and a magnetic detection element 20 is provided on the other side in the X direction. The magnetic detection element 20 is provided at a position facing the gap 14. In detail, the magnetic detection element 20 is provided at a position facing the gap 14 on the side farther from the axis CL relative to the gap 14. The magnetic detection element 20 is capable of outputting a signal corresponding to the magnetic flux flowing through the magnetic circuit 10.

[0082] The sixth to eleventh embodiments described above can also achieve the same effects and advantages as the first embodiment and others described above.

[0083] (Other embodiments) (1) In each of the above embodiments, the molded member 50 is made by integrally resin-molding the magnet 13, the first magnetostrictive material 11, the second magnetostrictive material 12, the first transmission member 31 and the second transmission member 32, excluding the magnetic detection element 20, but is not limited to this. For example, the molded member 50 may be made by integrally resin-molding the magnet 13, the first magnetostrictive material 11, the second magnetostrictive material 12, the first transmission member 31 and the second transmission member 32, including the magnetic detection element 20.

[0084] (2) In each of the above embodiments, a gap S1 is provided between all surfaces 56 of the molded member 50 that face radially outward and all surfaces 403 of the magnetic shield 40 that face radially inward, but this is not limited to this. For example, a gap S1 may be provided between some surfaces of the molded member 50 that face radially outward and some surfaces of the magnetic shield 40 that face radially inward. In this case, it is preferable that the some surfaces of the molded member 50 that face radially outward are more than half of the total radially outward area, and it is preferable that the some surfaces of the magnetic shield 40 that face radially inward are more than half of the total radially inward area. Furthermore, in each of the above embodiments, a gap S2 is provided between all the radially inward-facing surfaces 57 of the molded member 50 and all the radially outward-facing surfaces 404 of the magnetic shield 40, but this is not limited to this. For example, a gap S2 may be provided between some of the radially inward-facing surfaces of the molded member 50 and some of the radially outward-facing surfaces of the magnetic shield 40. In this case, it is preferable that the radially inward-facing surfaces of the molded member 50 comprise more than half of the total radially inward-facing area, and that the radially outward-facing surfaces of the magnetic shield 40 comprise more than half of the total radially outward-facing area.

[0085] (3) In the above embodiments, the mold member 50 was described as being made of a fiber-reinforced resin which is a resin material compounded with glass fibers or the like, but it is not limited to this. For example, the mold member 50 may be made of a fiber-reinforced resin which is a resin material compounded with carbon fibers or the like, or it may be made of resin material alone.

[0086] (4) In the second and third embodiments described above, two gate marks 58 and 59 were arranged symmetrically in the X-plane, but the invention is not limited to this, and two or more gate marks may be arranged symmetrically in the X-plane.

[0087] (5) In the fourth and fifth embodiments described above, one gate mark 501 was placed on the X plane, but the invention is not limited to this, and multiple gate marks may be placed on the X plane. Alternatively, two or more gate marks may be placed symmetrically on the X plane, and one or more gate marks may also be placed on the X plane.

[0088] (6) In the first and eighth embodiments described above, the magnetic detection element 20 was provided at a position facing the gap 14 in the axial direction. In the sixth and seventh embodiments, the magnetic detection element 20 was provided inside the gap 14. In the tenth and eleventh embodiments, the magnetic detection element 20 was provided at a position facing the gap 14 on the side closer to the axis CL or on the side farther from the axis CL. However, the magnetic detection element 20 may also be provided at an intermediate position between the positions shown in each embodiment.

[0089] The present invention is not limited to the embodiments described above, and can be modified as appropriate within the scope of the claims. Furthermore, the embodiments and parts thereof are not unrelated to each other, and can be combined as appropriate, except in cases where the combination is clearly impossible. In addition, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle. Furthermore, in the embodiments, when numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiments are mentioned, the invention is not limited to those specific numbers, except in cases where they are explicitly stated to be particularly essential or where they are clearly limited to a specific number in principle. Furthermore, when the shapes, positional relationships, etc., of the components, etc., are mentioned in the embodiments, the invention is not limited to those shapes, positional relationships, etc., except in cases where they are explicitly stated to be particularly essential or where they are clearly limited to a specific shape, positional relationship, etc., in principle.

[0090] The features of this invention are as follows: [Claim 1] In a load detection device that detects externally applied loads, A magnetic circuit (10) is configured in a ring shape such that the magnetic flux generated by the magnetic flux generating unit (13) generates magnetic flux, and a first magnetostrictive material (11) and a second magnetostrictive material (12) have permeability that changes according to an external force, and the magnetic flux generated by the magnetic flux generating unit flows in the order of the first magnetostrictive material, gap (14), second magnetostrictive material, and the magnetic flux generating unit. A first transmission member (31) transmits a load applied from the outside on one side in the direction in which the axis (CL) of the annular magnetic circuit extends to the first magnetostrictive material and the second magnetostrictive material, A second transmission member (32) transmits a load applied from the outside on the other side in the direction in which the axis extends to the first magnetostrictive material and the second magnetostrictive material, A magnetic detection element (20) is provided at a position opposite to the gap or within the gap, and outputs a signal corresponding to the magnetic flux flowing through the magnetic circuit, A load detection device comprising: a magnetic flux generating unit; a molded member (50) that integrally resin-moldes the first magnetostrictive material; the second magnetostrictive material; the first transmission member; and the second transmission member. [Claim 2] The load detection device according to claim 1, wherein the molded member integrally resin-moldes the magnetic flux generating unit, the first magnetostrictive material, the second magnetostrictive material, the first transmission member, and the second transmission member, excluding the magnetic detection element. [Claim 3] When, in the radial direction of a virtual circle perpendicular to the axis and centered on the axis, the side farther from the axis is called the radially outer side, the side closer to the axis is called the radially inner side, and the direction in which the axis extends is called the axial direction, The load detection device according to claim 1 or 2, wherein the molded member has an outer material removal portion (51) in a portion radially outward from the first magnetostrictive material and the second magnetostrictive material, and an inner material removal portion (52) in a portion radially inward from the first magnetostrictive material and the second magnetostrictive material. [Claim 4] The magnetic shield (40) further comprises at least a portion of the first transmission member and the second transmission member, the magnetic circuit, and the magnetic detection element, A load detection device according to any one of claims 1 to 3, wherein gaps (S1, S2) are provided between the radially outward-facing surface (56) of the molded member and the magnetic shield, and between the radially inward-facing surface (57) of the molded member and the magnetic shield. [Claim 5] The load detection device according to claim 4, wherein the gap between the magnetic shield and the molded member is provided between all surfaces of the molded member facing radially outward and the magnetic shield, and between all surfaces of the molded member facing radially inward and the magnetic shield. [Claim 6] When, in the radial direction of a virtual circle perpendicular to the axis and centered on the axis, the side farther from the axis is called the radially outer side, the side closer to the axis is called the radially inner side, and the direction in which the axis extends is called the axial direction, The aforementioned magnetic shield is A cylindrical outer cylinder portion (43) is provided radially outward from the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, A cylindrical inner cylinder portion (44) is provided radially inward from the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, A top plate portion (45) is provided on one side in the axial direction relative to the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, The magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element are provided on the other side in the axial direction, and the bottom plate portion (46) is provided on the other side in the axial direction. The load detection device according to claim 4 or 5, wherein the surface of the molded member facing in the axial direction, the top plate portion, and the bottom plate portion are provided with positioning portions (54, 55, 401, 402) for positioning the molded member and the magnetic shield. [Claim 7] The load detection device according to any one of claims 1 to 6, wherein the difference between the linear expansion coefficient of the molded member and the linear expansion coefficients of the first magnetostrictive material and the second magnetostrictive material is 15 ppm / °C or less. [Claim 8] The load detection device according to any one of claims 1 to 7, wherein the difference between the coefficient of linear expansion in the resin flow direction (MD) formed during injection molding of the mold member and the coefficient of linear expansion in the direction perpendicular to the resin flow direction (TD) is 15 ppm / °C or less. [Claim 9] The load detection device according to any one of claims 1 to 8, wherein the molded member is formed of a material containing glass fibers in resin. [Claim 10] When the plane line connecting the center of the magnetic flux generating section and the axis, and parallel to the axis, is called the X-plane, The load detection device according to any one of claims 1 to 9, wherein the gate marks (58, 59) which are traces of the gate where molten resin was injected into the mold from the gate during resin injection molding of the mold member are arranged symmetrically with respect to the X plane. [Claim 11] When the plane connecting the center of the magnetic flux generating section and the axis, and parallel to the axis, is called the X-plane, The load detection device according to any one of claims 1 to 10, wherein the gate mark (501), which is the mark of the gate where molten resin was injected into the mold from the gate during resin injection molding of the mold member, is located on the X plane. [Explanation of Symbols]

[0091] 1. Load detection device 10 Magnetic Circuit 11. First Magnetostrictive Material 12. Second Magnetostrictive Material 13 Magnetic flux generation section 14 Gap 20 Magnetic detection element 31 First transmission member 32 Second transmission member 50 molded components

Claims

1. In a load detection device that detects externally applied loads, A magnetic circuit (10) is configured in a ring shape such that the magnetic flux generated by the magnetic flux generating unit (13) generates magnetic flux, and a first magnetostrictive material (11) and a second magnetostrictive material (12) whose permeability changes according to an external force, and the magnetic flux generated by the magnetic flux generating unit flows in the order of the first magnetostrictive material, gap (14), second magnetostrictive material, and the magnetic flux generating unit. A first transmission member (31) transmits a load applied from the outside of one side in the direction in which the axis (CL) of the annular magnetic circuit extends to the first magnetostrictive material and the second magnetostrictive material, A second transmission member (32) transmits a load applied from the outside on the other side in the direction in which the axis extends to the first magnetostrictive material and the second magnetostrictive material, A magnetic detection element (20) is provided at a position opposite to the gap or within the gap, and outputs a signal corresponding to the magnetic flux flowing through the magnetic circuit. A load detection device comprising the magnetic flux generating unit, the first magnetostrictive material, the second magnetostrictive material, the first transmission member, and the second transmission member, all integrally molded in resin by a molded member (50).

2. The load detection device according to claim 1, wherein the molded member integrally resin-moldes the magnetic flux generating unit, the first magnetostrictive material, the second magnetostrictive material, the first transmission member, and the second transmission member, excluding the magnetic detection element.

3. When, in the radial direction of a virtual circle perpendicular to the axis and centered on the axis, the side farther from the axis is called the radially outer side, the side closer to the axis is called the radially inner side, and the direction in which the axis extends is called the axial direction, The load detection device according to claim 1 or 2, wherein the molded member has an outer material removal portion (51) in a portion radially outward from the first magnetostrictive material and the second magnetostrictive material, and an inner material removal portion (52) in a portion radially inward from the first magnetostrictive material and the second magnetostrictive material.

4. The magnetic shield (40) further comprises at least a portion of the first transmission member and the second transmission member, the magnetic circuit, and the magnetic detection element, The load detection device according to claim 1 or 2, wherein gaps (S1, S2) are provided between the radially outward-facing surface (56) of the molded member and the magnetic shield, and between the radially inward-facing surface (57) of the molded member and the magnetic shield.

5. The load detection device according to claim 4, wherein the gap between the magnetic shield and the molded member is provided between all surfaces of the molded member facing radially outward and the magnetic shield, and between all surfaces of the molded member facing radially inward and the magnetic shield.

6. When, in the radial direction of a virtual circle perpendicular to the axis and centered on the axis, the side farther from the axis is called the radially outer side, the side closer to the axis is called the radially inner side, and the direction in which the axis extends is called the axial direction, The aforementioned magnetic shield is A cylindrical outer cylinder portion (43) is provided radially outward from the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, A cylindrical inner cylinder portion (44) is provided radially inward from the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, A top plate portion (45) provided on one side in the axial direction relative to the magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element, The magnetic circuit, the first transmission member, the second transmission member, and the magnetic detection element are provided on the other side in the axial direction, and the bottom plate portion (46) is provided on the other side in the axial direction. The load detection device according to claim 4, wherein the surface of the molded member facing in the axial direction, the top plate portion, and the bottom plate portion are provided with positioning portions (54, 55, 401, 402) for positioning the molded member and the magnetic shield.

7. The load detection device according to claim 1 or 2, wherein the difference between the coefficient of linear expansion of the molded member and the coefficients of linear expansion of the first magnetostrictive material and the second magnetostrictive material is 15 ppm / °C or less.

8. The load detection device according to claim 1 or 2, wherein the difference between the coefficient of linear expansion in the resin flow direction (MD) formed during injection molding of the mold member and the coefficient of linear expansion in the direction perpendicular to the resin flow direction (TD) is 15 ppm / °C or less.

9. The load detection device according to claim 1 or 2, wherein the mold member is formed of a material containing glass fibers in resin.

10. When the plane connecting the center of the magnetic flux generating section and the axis, and parallel to the axis, is called the X-plane, The load detection device according to claim 1 or 2, wherein the gate marks (58, 59), which are traces of the gate where molten resin was injected into the mold from the gate during resin injection molding of the mold member, are arranged symmetrically with respect to the X plane.

11. When the plane connecting the center of the magnetic flux generating section and the axis, and parallel to the axis, is called the X-plane, The load detection device according to claim 1 or 2, wherein the gate mark (501), which is the mark of the gate where molten resin was injected into the mold from the gate during resin injection molding of the mold member, is arranged on the X plane.

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