JP5315148B2 - Magnetostrictive load sensor and moving body having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a highly reliable magnetostrictive load sensor capable of detecting both compressive force and tensile force; and a moving object equipped therewith. <P>SOLUTION: The magnetostrictive load sensor includes: a coil; a load detecting member inserted through a through-hole of the coil; a magnetic circuit forming member that forms a magnetic circuit and has a first portion which forms the magnetic circuit and a second portion provided in such a manner as to protrude from the first portion out of the magnetic circuit; a load transmitting member that transmits externally-applied compressive force and tensile force to the load detecting member; and a limiting member by which a relative change in position of the load detecting member along the central axis with respect to the magnetic circuit forming member is limited in such a range that the load transmitting member does not make contact with the first portion of the magnetic circuit forming member. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a magnetostrictive load sensor that electromagnetically detects a load using a magnetostrictive effect and a movable body including the magnetostrictive load sensor.

  Miniaturization is required for load sensors used in various moving bodies such as motorcycles, water bikes, and electric bicycles. A magnetostrictive load sensor has been put to practical use as a small load sensor. The magnetostrictive load sensor converts a change in magnetic characteristics of a member to which a load is applied into a change in voltage, and detects the load based on the change in voltage.

  A magnetostrictive load sensor capable of detecting not only a compressive load but also a tensile load is disclosed in Patent Document 1. FIG. 26 shows a magnetostrictive load sensor 1200 disclosed in Patent Document 1. The load sensor 1200 is disposed in a holder 1203 installed on the fixed base 1202 so as to be movable up and down.

  The load sensor 1200 includes a detection rod 1208, a coil (not shown) for magnetizing the detection rod 1208, and a case 1207 for housing these. The upper end of the detection rod 1208 protrudes upward from the upper end of the case 1207.

  A flange-shaped stopper portion 1203a is formed on the inner peripheral surface of the holder 1203, and a load sensor 1200 is disposed below the stopper portion 1203a. Further, a rod 1209 is disposed above the stopper portion 1203a. The upper end of the rod 1209 protrudes from the holder 1203 and is joined to the joint 1210.

  The load sensor 1200 is urged upward by a first spring 1205 provided at a lower portion in the holder 1203. The rod 1209 is urged downward by a second spring 1206 provided at the upper part in the holder 1203, and the lower end of the rod 1209 abuts on the upper end of the detection rod 1208 via the spacer 1211. The rod 1208 is pressed downward.

  The set load P1 of the first spring 1205 is set larger than the set load P2 of the second spring 1206 (that is, P1> P2). Therefore, in a state where no external load is applied to the rod 1209 (no load state), the load sensor 1200 is stationary with the upper surface of the case 1207 in contact with the lower surface of the stopper portion 1203a as shown in the figure. Yes. Therefore, in the no-load state, the set load P2 of the second spring 1206 acts as a compressive force on the detection rod 1208 of the load sensor 1200.

  In the load sensor 1200 having the above configuration, the preload by the second spring 1206 is always applied to the detection rod 1208 as a compression load. When a load in the compression direction is applied to the rod 1209 from the outside, the detected compression load increases. On the other hand, when a load in the pulling direction is applied to the rod 1209 from the outside, the detected compressive load decreases. That is, in this load sensor 1200, the compression force applied to the rod 1209 from the outside is detected as an increase in the compression load acting on the detection rod 1208, and the tensile force applied to the rod 1209 from the outside acts on the detection rod 1208. It is detected as a decrease in the compression load. Thus, the load sensor 1200 of Patent Document 1 can detect both the compressive force and the tensile force.

  However, in the load sensor 1200 of Patent Document 1, since it is necessary to apply a preload, there is a problem that the load range that can be used for detection is reduced to about half. In general, the spring has a manufacturing variation of about 10 to 20% in the elastic modulus. Therefore, it is necessary to adjust the set load for each sensor, which causes an increase in manufacturing cost. Furthermore, there has been a problem that the zero point output fluctuates due to a change in preload due to the spring sag.

  Patent Document 2 discloses a magnetostrictive load sensor that can detect a compressive force and a tensile force and does not need to apply a preload. FIG. 27 shows a magnetostrictive load sensor 1300 disclosed in Patent Document 2.

  The load sensor 1300 includes a coil 1310, a magnetic circuit forming member 1330, a rod-like member 1320, two load transmission members 1340a and 1340b, and a housing 1350.

  The coil 1310 includes a bobbin 1311 and a conducting wire 1312. A through hole 1310 h is formed in the axial center of the bobbin 1311. The conducting wire 1312 is wound around the bobbin 1311.

  The magnetic circuit forming member 1330 includes a cylindrical first casing member 1331 and a substantially disc-shaped second casing member 1332. The first casing member 1331 and the second casing member 1332 are made of a magnetic material, and function as a magnetic circuit when the load sensor 1300 operates.

  A coil 1310 is inserted into the first casing member 1331 via an annular elastic member 1319. A second casing member 1332 is coupled to the end of the first casing member 1331 by, for example, press fitting.

  A circular opening 1331 h is formed at the center of one end surface of the first casing member 1331, and a circular opening 1332 h is formed at the center of the second casing member 1332. Spacers SP are attached to the openings 1331h and 1332h, respectively.

  A cylindrical rod-shaped member 1320 is inserted into the through-hole 1310h and the openings 1331h and 1332h. Since the rod-shaped member 1320 is made of a magnetic material, it is magnetized by the coil 1310 when the load sensor 1300 is operated.

  One end 1320a of the rod-shaped member 1320 protrudes from the opening 1332h, and the other end 1320b of the rod-shaped member 1320 protrudes from the opening 1331h. The rod-shaped member 1320 is supported by load transmission members 1340a and 1340b.

  Each of the load transmission members 1340a and 1340b has a cylindrical shape. In addition, circular recesses 1343a and 1343b are formed at the centers of the one end surfaces of the load transmitting members 1340a and 1340b, respectively. One end portion 1320a of the rod-shaped member 1320 is inserted into the recess 1343a of the load transmission member 1340a, and the rod-shaped member 1320 and the load transmission member 1340a are joined. Further, the other end portion 1320b of the rod-shaped member 1320 is inserted into the concave portion 1343b of the load transmission member 1340b, and the rod-shaped member 1320 and the load transmission member 1340b are joined.

  The housing 1350 includes a cylindrical first housing 1351 and a substantially disk-shaped second housing 1352. A coil 1310, a magnetic circuit forming member 1330, a rod-like member 1320, and load transmission members 1340 a and 1340 b are accommodated in the first housing 1351. The first housing 1351 and the second housing 1352 are coupled by a plurality of bolts 1359.

  A plurality of O-rings O1 to O4 made of an elastic resin or the like are attached to the first housing 1351 and the second housing 1352. A circular opening 1351h is formed at the center of the end surface of the first housing 1351, and the load transmission member 1340b is supported by the O-ring O1 in the opening 1351h. A circular opening 1352h is formed at the center of the second housing 1352, and the load transmission member 1340a is supported by the O-ring O4 in the opening 1352h.

  Each of the load transmission members 1340a and 1340b is integrally formed with load transmission shafts 1341a and 1341b so as to extend outward of the load sensor 1300 on the axis of the rod-shaped member 1320. Further, annular members 1342a and 1342b are integrally formed at the respective ends of the load transmission shafts 1341a and 1341b.

  When a compressive load (a load in the direction J1) is applied between the two annular members 1342a and 1342b on the shaft of the rod-shaped member 1320, a compressive force acts on the rod-shaped member 1320 via the load transmitting members 1340a and 1340b. Further, when a tensile load (a load in the direction J2) is applied between the two annular members 1342a and 1342b on the axis of the rod-shaped member 1320, a tensile force acts on the rod-shaped member 1320 via the load transmitting members 1340a and 1340b.

  When compressive force or tensile force is applied to the rod-shaped member 1320, the magnetic permeability of the rod-shaped member 1320 changes due to the inverse magnetostrictive effect, and the impedance of the sensor component composed of the coil 1310, the magnetic circuit forming member 1330, and the rod-shaped member 1320 changes. To do. As a result, the induced electromotive force (voltage) generated in the coil 1310 changes. By detecting this voltage change by the peripheral circuit, it is possible to detect both the compressive load and the tensile load.

  Since the magnetostrictive load sensor 1300 of Patent Document 2 described above does not need to be preloaded, it can take a wide usable load range.

JP 2003-57127 A International Publication No. 2007/004472 Pamphlet

  However, according to the study of the present inventor, it has been found that the following problems occur in the magnetostrictive load sensor 1300 of Patent Document 2.

  It is preferable that the load sensor capable of detecting both the compressive force and the tensile force can be suitably used even when the housing is not installed on the movable body. This is because if the housing is installed on the moving body, the load sensor itself cannot be displaced, so that its use is limited.

  However, in the load sensor 1300 of Patent Document 2, since the load transmission members 1340a and 1340b are supported only by the elastic force of the O-rings O1 and O4, the magnetic force of the rod-like member 1320 supported by the load transmission members 1340a and 1340b. The relative position with respect to the circuit forming member 1330 may change. For example, when the moving body suddenly stops when the moving body is moving in the central axis direction of the rod-shaped member 1320, the load transmitting members 1340a and 1340b connected to the outside of the load sensor 1300 via the annular members 1342a and 1342b While the rod-shaped member 1320 stops moving, the housing 1350 and the magnetic circuit forming member 1330 supported by the housing 1350 continue to move due to inertia. Therefore, the relative position of the rod-shaped member 1320 with respect to the magnetic circuit forming member 1330 changes greatly. Since the magnetic resistance of the rod-shaped member 1320 differs somewhat depending on the part, if the relative position of the rod-shaped member 1320 with respect to the magnetic circuit forming member 1330 changes greatly, the magnetic characteristics may fluctuate and affect the sensor output. Further, when the relative position of the rod-shaped member 1320 changes extremely, the load transmission member 1340a or 1340b may come into contact with the magnetic circuit forming member 1330, and accurate load detection may be hindered.

  As described above, the magnetostrictive load sensor 1300 of Patent Document 2 can detect the compressive force and the tensile force, but lacks reliability.

  The present invention has been made in view of the above problems, and an object thereof is to detect both a compressive force and a tensile force, and to provide a highly reliable magnetostrictive load sensor and such a magnetostrictive load. It is providing the mobile body provided with the sensor.

  A magnetostrictive load sensor according to the present invention includes a coil having a through hole, a load detection member inserted into the through hole, and a magnetic circuit forming member that forms a magnetic circuit through which a magnetic flux generated by a current flowing through the coil passes. A magnetic circuit forming member having a first part forming a magnetic circuit and a second part provided so as to extend outward from the first part to the magnetic circuit, and a compressive load applied from the outside And a load transmission member that transmits a tensile load to the load detection member, and a relative position change of the load detection member along the central axis direction with respect to the magnetic circuit formation member. And a restricting member that restricts the load transmitting member to a range in which the load transmitting member does not come into contact therewith.

  In a preferred embodiment, the restricting member is provided outside the magnetic circuit.

  In a preferred embodiment, the load detecting member or the load transmitting member has a deformed portion having a different outer peripheral shape from other portions of the member, and the restricting member is a lock for locking the deformed portion. Part.

  In a preferred embodiment, the surface of the load detection member has a shape magnetic anisotropy different from the inside of the load detection member.

  In a preferred embodiment, the surface of the load detection member has a plurality of stripe-shaped grooves extending in a direction inclined with respect to the central axis of the load detection member, and a direction inclined with respect to the central axis of the load detection member Or a plurality of stripe-shaped magnetic ribbons extending in a direction inclined with respect to the central axis of the load detection member.

  In a preferred embodiment, the plurality of grooves, the plating pattern, or the plurality of magnetic ribbons form an angle of 14.2 ° or more and 65.5 ° or less with a direction orthogonal to a central axis of the load detection member. .

  In a preferred embodiment, the load transmission member includes a coupling portion rotatably coupled to the load detection member.

  In a preferred embodiment, an end surface of the load detection member that contacts the coupling portion or an end surface of the coupling portion that contacts the load detection member has a substantially spherical shape.

  In a preferred embodiment, the coupling portion is a receiving member that comes into contact with one end of the load detecting member, and the load transmitting member further elastically biases the receiving member toward the load detecting member. including.

  In a preferred embodiment, the magnetostrictive load sensor according to the present invention includes a relief mechanism that rotatably couples the load transmission member to the load detection member.

  In a preferred embodiment, the escape mechanism includes a rod-shaped member extending in a direction intersecting with a central axis of the load detection member, and a housing member having a through-hole into which the rod-shaped member is inserted, and the through-hole Is larger than the outer diameter of the rod-shaped member, and a load is transmitted between the outer circumferential surface of the rod-shaped member and the inner circumferential surface of the through hole of the housing member.

  In a preferred embodiment, the magnetostrictive load sensor according to the present invention further comprises a connecting member coupled directly or indirectly to the load transmitting member and for connecting the magnetostrictive load sensor to the outside.

  In a preferred embodiment, the connecting member includes a spherical sliding bearing.

  In a preferred embodiment, the magnetostrictive load sensor according to the present invention further comprises a housing that houses the coil, the load detection member, and the magnetic circuit forming member, and the housing is the second of the magnetic circuit forming member. Hold and fix the part.

  A moving body according to the present invention includes a magnetostrictive load sensor having the above-described configuration.

  According to the present invention, a magnetostrictive load sensor that can detect both compressive force and tensile force and has high reliability is provided. Moreover, according to this invention, the mobile body provided with such a magnetostrictive load sensor is provided.

It is a figure showing typically magnetostriction type load sensor 100 in a suitable embodiment of the present invention. It is a figure showing typically magnetostriction type load sensor 100 in a suitable embodiment of the present invention. (A) And (b) is sectional drawing which shows typically the magnetostrictive load sensor 100a in suitable embodiment of this invention. (A) And (b) is sectional drawing which shows typically the connection structure of the one end part of a rod-shaped member, and a load transmission member. It is sectional drawing which shows typically the connection structure of the one end part of a rod-shaped member, and a load transmission member. It is sectional drawing which shows typically the connection structure of the one end part of a rod-shaped member, and a load transmission member. It is sectional drawing which shows an example of the specific structure of a housing. It is a side view which shows an example of the preferable structure of a rod-shaped member. (A)-(c) is a figure which shows the example of the cross-sectional shape of the diagonal groove | channel provided in the surface of a rod-shaped member. (A) And (b) is a graph which shows the relationship between a load (N) and sensor sensitivity ((DELTA) Z / Z0). (A) corresponds to the case where no oblique groove is provided on the surface of the rod-like member, and (b) is provided with an oblique groove so that the angle θ formed with the direction perpendicular to the central axis of the rod-like member is 30 °. Corresponds to the case. It is a figure which shows typically the magnetization direction of the rod-shaped member in case the diagonal groove | channel is not provided. It is a figure which shows typically the magnetization direction of a rod-shaped member in case an oblique groove is provided. (A) And (b) is a graph which shows the relationship between angle (theta) (degree) of a diagonal groove | channel, and sensor sensitivity ((DELTA) Z / Z0). (A) And (b) is a side view which shows an example of the preferable structure of a rod-shaped member. It is a figure showing typically magnetostriction type load sensor 100b in a suitable embodiment of the present invention. (A) And (b) is sectional drawing which shows typically the magnetostrictive load sensor 100c in suitable embodiment of this invention. It is sectional drawing which shows typically the connection structure of the other end part of a rod-shaped member, and a load transmission member. (A) And (b) is a side view which shows typically the magnetostrictive load sensor 100d in suitable embodiment of this invention. It is a perspective view which shows typically the 1st, 2nd and 3rd connection member with which the magnetostrictive load sensor 100d is provided. It is sectional drawing which shows typically the 1st, 2nd and 3rd connection member with which the magnetostrictive load sensor 100d is provided. (A) And (b) is a figure for demonstrating the coupling | bonding procedure of a 1st connection member, a 2nd connection member, a 3rd connection member, and a rod-shaped member. (A) And (b) is a figure for demonstrating the coupling | bonding procedure of a 1st connection member, a 2nd connection member, a 3rd connection member, and a rod-shaped member. It is a perspective view which shows typically the 1st, 2nd and 3rd connection member with which the magnetostrictive load sensor 100d is provided. 1 is a block diagram showing a schematic configuration of a load detection circuit 600 using a magnetostrictive load sensor 100. FIG. It is a figure which shows typically the shift load detection apparatus 700 provided with the magnetostrictive load sensor 100a. 2 is a cross-sectional view schematically showing a magnetostrictive load sensor 1200 of Patent Document 1. FIG. FIG. 6 is a cross-sectional view schematically showing a magnetostrictive load sensor 1300 of Patent Document 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

  First, the basic structure of the magnetostrictive load sensor 100 according to this embodiment will be described with reference to FIG. The load sensor 100 includes a coil A, a load detection member B, a magnetic circuit forming member C, two load transmission members Da and Db, and a housing E. The load transmission member Da and the housing E also function as a “restriction member” described later.

  The load detection member B and the magnetic circuit forming member C are made of a magnetic material. On the other hand, the load transmission members Da and Db and the housing E are made of a nonmagnetic material.

  A magnetic material is a material having a property of being magnetized when placed in a magnetic field. Examples of magnetic materials include iron-based materials, iron-chromium-based materials, iron-nickel-based materials, iron-cobalt-based materials, iron-silicon-based materials, iron-aluminum-based materials, pure iron, permalloy or giant magnetostrictive materials, and ferrite-based stainless steel (for example, SUS430) is used. The magnetism of a magnetic material is expressed by the magnetic permeability. For example, the relative permeability of iron (the ratio of the permeability to the vacuum permeability) is 200.

  Further, the nonmagnetic material is a material other than the magnetic material, and is typically a material having a relative permeability of about 1. As the nonmagnetic material, for example, austenitic stainless steel (for example, SUS304), aluminum, and copper are used, and their relative magnetic permeability is 1-1.01.

  The coil A has a through hole Ah. Although not shown here, the coil A includes at least a conducting wire wound a plurality of times.

  The load detection member B has a rod-like shape. The load detection member B is inserted into the through hole Ah of the coil A.

  The magnetic circuit forming member C forms a magnetic circuit through which the magnetic flux generated by the current flowing through the coil A passes. The magnetic circuit forming member C covers the outer peripheral portion and both end portions of the coil A. Openings Ch are formed at the centers of both end surfaces of the magnetic circuit forming member C, and both end portions of the load detection member B protrude from the opening Ch.

  The load transmitting members Da and Db transmit a compressive load and a tensile load applied from the outside to the load detecting member B. One of the load transmission members Da and Db is coupled to one end of the load detection member B. The other load transmission member Db is coupled to the other end of the load detection member B.

  The housing E accommodates the coil A, the load detection member B, and the magnetic circuit forming member C.

  The load transmission member Da and the housing E transmit a relative positional change (more specifically, a positional change along the central axis direction) of the load detection member B to the magnetic circuit forming member C to the magnetic circuit forming member C. It limits to the range which members Da and Db do not contact. In the example shown in FIG. 1, the load transmitting member Da has a deformed portion Da1 having a different outer peripheral shape from other portions, and the deformed portion Da1 is locked by a part (locking portion) Ea of the housing E. As a result, the position change of the load detection member B is limited.

  Although not shown in FIG. 1, the conducting wire (lead wire) drawn out from the coil A is taken out of the magnetic circuit forming member C through a conducting wire extraction hole formed in the magnetic circuit forming member C, and the oscillation circuit , Connected to a peripheral circuit (load detection circuit) including a voltage detector (or current detector), a rectifier circuit, an amplifier circuit, and the like.

  Next, the operation of the load sensor 100 will be described. An alternating current is supplied to the coil A through a lead wire by an oscillation circuit of a peripheral circuit (not shown), and the coil A is driven. At this time, the coil A functions as an exciting coil, and the load detection member B is magnetized. The magnetic circuit forming member C functions as a magnetic circuit.

  FIG. 2 schematically shows a magnetic circuit formed in the load sensor 100. In FIG. 2, the direction of the magnetic field when the coil A is driven is indicated by an arrow. As can be seen from FIG. 2, when the coil A is driven, a magnetic flux line (magnetic circuit) that forms a closed circuit is formed.

  In the load sensor 100, since the load transmitting members Da and Db transmit the compressive load and the tensile load applied from the outside to the load detecting member B, both the compressive force and the tensile force can be detected. When a compressive load is applied between the load transmitting members Da and Db, the compressive load is transmitted to both ends of the load detecting member B. Thereby, a compressive force acts on the load detection member B. Further, when a tensile load is applied between the load transmitting members Da and Db, the tensile load is transmitted to both ends of the load detecting member B. Thereby, a tensile force acts on the load detection member B. When compressive force or tensile force acts on the load detection member B, the magnetic permeability of the load detection member B changes due to the inverse magnetostrictive effect, and an assembly of the coil A, the load detection member B, and the magnetic circuit forming member C (“sensor component” The impedance of “.” Is changed. As a result, the induced electromotive force (voltage) generated in the coil A changes. At this time, the coil A functions as a detection coil, and the voltage in the coil A is detected by the peripheral circuit via the lead wire. Based on the detected voltage change of the coil A, the load applied to the load transmitting members Da and Db is detected.

  In the magnetostrictive load sensor 100 according to this embodiment, unlike the load sensor 1200 disclosed in Patent Document 1, it is not necessary to apply a preload by a spring. Therefore, a usable load range can be widened. Further, it is not necessary to adjust the set load of the spring for applying the preload, and there is no problem that the zero point output fluctuates due to the temporal change of the preload caused by the spring sag.

  Furthermore, the load sensor 100 in the present embodiment includes a limiting member that limits a change in position of the load detection member B along the central axis direction (that is, a change in position relative to the magnetic circuit forming member C). For this reason, a large change in the relative position of the load detection member B with respect to the magnetic circuit forming member C is prevented, so that it is possible to suppress a change in the magnetic characteristics of the sensor constituent part and the accompanying adverse effects on the sensor output. Further, detection failure due to the load transmission members Da and Db coming into contact with the magnetic circuit forming member C is also prevented. Therefore, the load sensor 100 is excellent in reliability even in a usage mode in which the support member E is not installed on the movable body.

  Further, as can be seen from FIG. 2, the load transmission member Da and the housing 50, which are limiting members, are provided outside the magnetic circuit. As described above, by providing the limiting member outside the magnetic circuit, the load detection member B is not adversely affected by the sensor output (that is, no extra stress is applied to the load detection member B or the magnetic circuit forming member C). It is possible to limit the position change of the.

  Further, when the load transmitting member Da has the deformed portion Da1 and the restricting member has the locking portion Ea for locking the deformed portion Da1 as in the present embodiment, the load can be reduced with a relatively simple configuration. The change in position of the detection member B can be more reliably limited.

  In addition, as shown in FIG. 2, the magnetic circuit formation member C in this embodiment was provided so that it might extend outside the magnetic circuit from 1st part Ca which forms a magnetic circuit, and 1st part Ca. And a second portion Cb. Below, the 1st part Ca which forms a magnetic circuit is called a "main-body part", and the 2nd part Cb extended outside from the main-body part Ca is called a "flange part." In FIG. 2, the flange portion Cb is hatched. As shown in FIG. 2, the housing E holds and fixes the flange portion Cb of the magnetic circuit forming member C. Therefore, the sensor component including the coil A, the load detection member B, and the magnetic circuit forming member C is supported outside the magnetic circuit. Thus, if the sensor component is supported outside the magnetic circuit, the sensor output is less susceptible to vibration and impact.

  Further, since the flange portion Cb of the magnetic circuit forming member C is located outside the magnetic circuit, even if another member contacts the flange portion Cb, the influence on the sensor output is small. Therefore, if the limiting member limits the position of the load detecting member B so that the load transmitting members Da and Db do not contact the main body portion Ca of the magnetic circuit forming member C, an effect of improving the reliability can be obtained.

  Subsequently, a more specific structure of the magnetostrictive load sensor including the limiting member will be described.

  An example of a specific structure of a magnetostrictive load sensor including a limiting member is shown in FIG. 3A and 3B are cross-sectional views schematically showing the magnetostrictive load sensor 100a, both of which show a cross section passing through the central axis of the load sensor 100a. The cross section shown in FIG. 3A and the cross section shown in FIG. 3B are orthogonal to each other.

  A load sensor 100 a shown in FIGS. 3A and 3B includes a coil 10, a load detection member 20, a magnetic circuit forming member 30, load transmission members 40 and 42, and a housing 50. As will be described later, the housing 50 constitutes a part of the load transmission member 40. Moreover, the load transmission members 40 and 42 also function as limiting members.

  The coil 10 includes a bobbin (winding frame) 11 and a conductive wire 12 wound around the bobbin 11. A through hole is formed in the axial center of the bobbin 11. A part (lead wire) 12 ′ of the conducting wire 12 is drawn out from the coil 10.

  The load detection member 20 has a rod shape and is inserted into the through hole of the coil 10. Hereinafter, the load detection member 20 is simply referred to as a rod-shaped member. More specifically, the rod-shaped member 20 is substantially cylindrical. However, the one end portion 20a of the rod-shaped member 20 has an outer peripheral shape different from other portions of the rod-shaped member 20, and more specifically, has an outer diameter larger than that of the other portions. That is, the one end portion 20a of the rod-shaped member 20 is a large-diameter portion having a larger outer diameter than other portions. Since the rod-shaped member 20 is made of a magnetic material, it is magnetized by the coil 10 during the operation of the load sensor 100a.

  The magnetic circuit forming member 30 includes a substantially cylindrical first casing member 31 having an outer peripheral surface and a bottom surface, and a substantially disk-shaped second casing member 32. Since the first casing member 31 and the second casing member 32 are each formed of a magnetic material, each of the first casing member 31 and the second casing member 32 functions as a magnetic circuit when the load sensor 100a is operated. . However, the outer peripheral portion 32a of the second casing member 32 extends outward from the magnetic circuit and corresponds to the flange portion Cb shown in FIG.

  The coil 10 is inserted into the first casing member 31. A second casing member 32 is coupled to an end portion of the first casing member 31, and the coil 10 is accommodated in a space surrounded by the first casing member 31 and the second casing member 32. The coupling between the first casing member 31 and the second casing member 32 is performed by press-fitting, for example.

  A circular opening is formed at the center of the bottom surface of the first casing member 31. A circular opening is also formed at the center of the second casing member 32. One end portion 20a and the other end portion 20b of the rod-shaped member 20 protrude from these openings.

  The load transmission member 40 includes a housing 50 and a receiving member 41 that comes into contact with one end portion (large diameter portion) 20 a of the rod-shaped member 20. The housing 50 has two spaces S1 and S2. Most of the rod-shaped member 20, the magnetic circuit forming member 30, and the load transmitting member 42 are accommodated in one space S1. Moreover, the one end part (large diameter part) 20a and the receiving member 41 of the rod-shaped member 20 are accommodated in the other space S2.

  The receiving member 41 has a substantially cylindrical shape, and has a concave portion 41a on one end face (end face on the rod-like member 20 side). The recess 41 a of the receiving member 41 is engaged with one end (large diameter portion) 20 a of the rod-shaped member 20. The receiving member 41 is made of a nonmagnetic material.

  The housing 50 includes a locking portion 50a that locks the end surface of the large-diameter portion 20a of the rod-shaped member 20 (the end surface opposite to the receiving member 41). The large-diameter portion 20a of the rod-shaped member 20 is sandwiched between the receiving member 41 and the locking portion 50a of the housing 50, whereby the one end portion 20a of the rod-shaped member 20 and the load transmission member 40 are coupled. .

  Moreover, the change of the relative position with respect to the magnetic circuit formation member 30 is restrict | limited to the one end part (large diameter part) 20a of the rod-shaped member 20 by said structure. Specifically, the change in the position of the large-diameter portion 20a is limited to a range in which no other member comes into contact with the magnetic circuit forming member 30 (more strictly, the main body portion of the magnetic circuit forming member 30). That is, the housing 50 and the receiving member 41 constituting the load transmitting member 40 function as a limiting member cooperatively.

  The load transmission member 42 has a substantially cylindrical shape, and has a concave portion 42a on one end face (end face on the rod-like member 20 side). The recess 42 a of the load transmitting member 42 is fitted with the other end 20 b of the rod-shaped member 20. Here, the other end 20b of the rod-shaped member 20 and the load transmission member 42 are coupled by screwing, and a nut 43 is screwed in the vicinity of the other end 20b of the rod-shaped member 20. The other end 20b of the rod-shaped member 20 may be coupled to the load transmission member 42 by adhesion, welding, or press fitting, or may be performed using a coupling member such as a pin. The load transmission member 42 is made of a nonmagnetic material.

  One end portion (end portion on the rod-like member 20 side) 42b of the load transmitting member 42 is a large-diameter portion having a larger outer diameter than other portions. The housing 50 has a locking portion 50b that locks the large-diameter portion 42b of the load transmitting member 42. Further, a part of the load transmitting member 42 protrudes outward from one end of the housing 50, and the protruding portion also has a large diameter portion 42c. One end portion 50c of the housing 50 functions as a locking portion that locks the large diameter portion 42c. Although predetermined gaps are provided between the locking portion 50b and the large diameter portion 42b and between the locking portion 50c and the large diameter portion 42c, an excessive tensile load is applied to the load transmission member 42 from the outside. When added, the large-diameter portion 42b is brought into contact with and locked with the locking portion 50b. Further, when an excessive compressive load is applied to the load transmission member 42 from the outside, the large diameter portion 42c comes into contact with and is locked with the locking portion 50c.

  The other end portion 20 b of the rod-shaped member 20 is restricted from changing in position relative to the magnetic circuit forming member 30 by the load transmitting member 42 and the housing 50 having the above-described structure. Specifically, the position change of the other end 20b is limited to a range in which no other member comes into contact with the magnetic circuit forming member 30 (more strictly, the main body of the magnetic circuit forming member 30). That is, the load transmission member 42 and the housing 50 cooperatively function as a limiting member.

  As described above, the housing 50 accommodates the coil 10, the rod-shaped member 20, the magnetic circuit forming member 30, the receiving member 41, and the load transmitting member 42. The housing 50 is made of a nonmagnetic material. The housing 50 is held and fixed so as to sandwich the flange portion of the magnetic circuit forming member 30 (the outer peripheral portion 32a of the second casing member 32). An annular elastic member (packing) 58 is provided between the second casing member 32 and the housing 50.

  In FIG. 3, the housing 50 is illustrated as one continuous member. However, in actuality, the housing 50 includes a plurality of members each having a predetermined shape, and the plurality of members constituting the housing 50 are configured. These members are connected to each other by, for example, a bolt 59 as shown.

  The load sensor 100a further includes connecting members 61 and 62 for connecting the load sensor 100a to the outside. The connecting members 61 and 62 are provided at both ends of the load sensor 100.

  The connecting member 61 has a load transmission shaft 61a joined to the housing 50, and an annular member 61b provided at an end of the load transmission shaft 61a. That is, the connecting member 61 is directly coupled to the load transmission member 40. The connecting member 62 includes a load transmission shaft 62a joined to the load transmission member 42, and an annular member 62b provided at an end of the load transmission shaft 62a. That is, the connecting member 62 is directly coupled to the load transmitting member 42. The joining of the connecting member 61 to the housing 50 and the joining of the connecting member 62 to the load transmitting member 42 are performed by screwing, adhesion, welding, press fitting, or the like. The connecting members 61 and 62 may be indirectly coupled to the load transmitting members 40 and 42 via other members. Further, when the connecting members 61 and 62 are directly coupled to the load transmitting members 40 and 42, the connecting members 61 and 62 may be formed integrally with the load transmitting members 40 and 42, respectively.

  As described above, the magnetostrictive load sensor 100a includes the limiting members (specifically, the housing 50, the receiving member 41, and the load transmitting member 42) that limit the position change along the central axis direction of the rod-shaped member 20. . Therefore, since the change in the relative position of the rod-shaped member 20 with respect to the magnetic circuit forming member 30 is limited (that is, the large position change is prevented), the fluctuation of the magnetic characteristics of the sensor component and the accompanying adverse effect on the sensor output are suppressed. can do. Further, poor detection due to contact of other members (for example, the receiving member 41 and the load transmitting member 42) with the magnetic circuit forming member 30 is also prevented. Therefore, the magnetostrictive load sensor 100a is excellent in reliability even in a usage mode in which the housing 50 is not installed on the moving body.

  The load sensor 100a according to the present embodiment includes a limiting member (housing 50 and receiving member 41) that limits the position on one end 20a side of the rod-shaped member 20, and a limiting member (load transmitting member) that limits the position on the other end 20b side. 42 and housing 50). That is, the limiting member is provided on both the one end 20 a side and the other end 20 b side of the rod-shaped member 20. Therefore, even if the rod-shaped member 20 is broken during use of the load sensor 100a (for example, between the large-diameter portion 20a of the rod-shaped member 20 and the large-diameter portion 42b of the load transmission member 42 or the large diameter of the load transmission member 42). Even if it is broken between the portions 42b and 42c), the broken rod-shaped member 20 is prevented from falling off from the load sensor 100a.

  Further, the member functioning as the limiting member is provided outside the magnetic circuit. Thus, by providing the limiting member on the outside of the magnetic circuit, the position of the rod-shaped member 20 does not adversely affect the sensor output (that is, no excessive stress is applied to the rod-shaped member 20 or the magnetic circuit forming member 30). Change can be limited.

  Furthermore, the rod-shaped member 20 and the load transmission member 42 have large-diameter portions 20a, 42b, and 42c, respectively, and the housing 50, which is a limiting member, locks the large-diameter portions 20a, 42b, and 42c. Since it has 50b and 50c, the position change of the rod-shaped member 20 can be more reliably restricted with a comparatively simple structure.

  In the load sensor 100a, the magnetic circuit forming member 30 has a flange portion 32a provided so as to extend outward from the magnetic circuit, and the housing 50 holds and fixes the flange portion 32a. Therefore, the sensor component including the coil 10, the rod-shaped member 20, and the magnetic circuit forming member 30 is supported outside the magnetic circuit. Therefore, in the load sensor 100a, the sensor output is not easily affected by vibration or impact.

  Further, in the load sensor 100a, as already described, one end portion (large diameter portion) 20a of the rod-shaped member 20 is sandwiched between the receiving member 41 and the locking portion 50a of the housing 50, and thereby the receiving member 41. This structure is enlarged and shown in FIG.

  As shown in FIG. 4A, the end surface 20a1 of the large-diameter portion 20a opposite to the receiving member 41 is in contact with and locked with the locking portion 50a of the housing 50. Further, the end surface 20 a 2 on the receiving member 41 side of the large diameter portion 20 a has a substantially spherical shape and is in contact with the bottom surface 41 a 1 of the concave portion 41 a of the receiving member 41. A predetermined gap is provided between the outer peripheral surface 20a3 of the large-diameter portion 20a and the inner peripheral surface 41a2 of the concave portion 41a.

  When the one end portion 20a of the rod-shaped member 20 and the load transmitting member 40 are coupled with each other as described above, the rod-shaped member 20 can rotate when an external force that twists the rod-shaped member 20 is applied. That is, the load transmission member 40 includes a coupling portion (receiving member 41) that is rotatably coupled to the one end portion 20a of the rod-shaped member 20. Therefore, it is possible to prevent the torsional stress from being applied to the rod-shaped member 20. Therefore, it is possible to prevent irreversible damage and plastic deformation from being applied to the rod-shaped member 20 due to twisting, and the reliability is further improved.

  As illustrated in FIG. 4A, it is preferable that the end surface 20a2 of the rod-shaped member 20 that contacts the coupling portion (receiving member 41) has a substantially spherical shape. When the end surface 20a2 has a substantially spherical shape, the rotational resistance between the end surface 20a2 and the coupling portion is reduced.

  If at least one of both ends of the rod-shaped member 20 is rotatably coupled to the load transmitting member 40 and / or 42, an effect of preventing application of torsional stress to the rod-shaped member 20 can be obtained. The specific structure for this purpose is not limited to that illustrated in FIG.

  For example, as shown in FIG. 4B, the end surface 20a2 of the rod-shaped member 20 that contacts the receiving member 41 is planar, and instead, the end surface 41a1 of the receiving member 41 that contacts the rod-shaped member 20 has a substantially spherical shape. You may have. Even with such a configuration, it is possible to reduce the rotational resistance between the end surface 20a2 of the rod-shaped member 20 and the receiving member 41 that is the coupling portion.

  Or as shown in FIG. 5, the one end part 20a of the rod-shaped member 20 does not need to be a large diameter part. A connecting member 48 made of a nonmagnetic material is joined to one end 20a of the rod-shaped member 20 shown in FIG. The connection member 48 is joined to the rod-like member 20 by press-fitting, screwing, adhesion, or the like. The connecting member 48 has a small diameter portion 48a having a relatively small outer diameter and a large diameter portion 48b having a relatively large outer diameter.

  An end face 48b1 of the large diameter portion 48b of the connecting member 48 on the side opposite to the receiving member 41 is in contact with and locked with the locking portion 50a of the housing 50. Further, the end surface 48 b 2 on the receiving member 41 side of the large diameter portion 48 b is in contact with the bottom surface 41 a 1 of the recess 41 a of the receiving member 41. A predetermined gap is provided between the outer peripheral surface 48b3 of the large diameter portion 48b and the inner peripheral surface 41a2 of the concave portion 41a.

  In the example shown in FIG. 5, the connecting member 48 constitutes the load transmitting member 40 in addition to the housing 50 and the receiving member 41. As shown in FIG. 5, even if the connecting member 48 constituting the load transmitting member 40 is provided with the large diameter portion 48 b, the position change of the rod-shaped member 20 can be limited.

  Moreover, as shown in FIG. 6, you may provide the elastic member 57 which urges | biases the receiving member 41 to the rod-shaped member 20 side. The elastic member 57 is a disc spring, for example. By this elastic member 57, the receiving member 41 is pressed against the large diameter portion 20 a of the rod-shaped member 20. In this configuration, the load transmission member 40 includes a housing 50, a receiving member 41, and an elastic member 57.

  In the configuration shown in FIG. 6, the rod-shaped member 20 rotates when a stress (torque) that twists the rod-shaped member 20 exceeds a certain level. Therefore, plastic deformation of the rod-shaped member 20 due to excessive torque can be prevented. In addition, since the elastic member 57 that biases the receiving member 41 toward the bar-shaped member 20 is provided instead of simply making the bar-shaped member 20 rotatable, the elastic member 57 can be rotated by adjusting the elastic modulus of the elastic member 57. It is possible to accurately set the magnitude of torque (limit torque) that starts. 6 illustrates the case where the end surface 20a2 on the receiving member 41 side of the rod-shaped member 20 has a substantially spherical shape, but the receiving member 41 side of the rod-shaped member 20 is similar to FIG. 4B. The end surface 20a2 of the receiving member 41 may be planar, and the end surface 41a1 of the receiving member 41 that contacts the rod-shaped member 20 may be substantially spherical.

  FIG. 7 shows an example of a specific structure of the housing 50. A housing 50 shown in FIG. 7 includes a first housing member 51, a second housing member 52, and a holder 53. The first housing member 51 and the second housing member 52 are coupled to each other by a bolt 59. The holder 53 is disposed between the first housing member 51 and the second housing member 52.

  In the space S1 defined by the first housing member 51 and the holder 53, most of the rod-shaped member 20, the magnetic circuit forming member 30, and the load transmitting member 42 are accommodated. In addition, in the space S <b> 2 defined by the second housing member 52 and the holder 53, one end portion (large diameter portion) 20 a of the rod-shaped member 20 and the receiving member 41 are accommodated. Note that the receiving member 41 may be omitted, and only the large-diameter portion 20a of the rod-shaped member 20 may be accommodated in the space S2. In that case, the size of the space S <b> 2 is set smaller than when the receiving member 41 is accommodated, and the second housing member 52 and the holder 53 function as the load transmitting member 40.

  In the housing 50 shown in FIG. 7, the first housing member 51 and the holder 53 sandwich and hold and fix the flange portion 32 a of the magnetic circuit forming member 30. In addition, a part of the holder 53 and a part of the first housing member 51 function as the locking portions 50a, 50b, and 50c shown in FIG. And the change in the position of the rod-shaped member 20 are restricted. The specific structure of the housing 50 is not limited to that illustrated in FIG.

  Then, the preferable structure of the rod-shaped member 20 is demonstrated.

  Magnetic anisotropy is known as one of the characteristics of a magnetic material. Magnetic anisotropy refers to the property that a magnetic material has an easy magnetization direction (easy magnetization axis) and a difficult direction (hard magnetization axis). The rod-shaped member 20 has magnetic anisotropy (shape magnetic anisotropy) derived from the shape, and is easily magnetized in the longitudinal direction (direction parallel to the central axis). The inventor of the present application has studied in detail the relationship between the shape magnetic anisotropy of the rod-shaped member 20 and the sensor sensitivity of the load sensor 100a. As a result, the surface of the rod-shaped member 20 has a different shape magnetic difference from the inside of the rod-shaped member 20. It has been found that the sensitivity to the compressive force and the sensitivity to the pulling force of the load sensor 100a can be equalized if it has directionality.

  In order to give the surface of the rod-shaped member 20 a shape anisotropy different from the inside, for example, as shown in FIG. 8, the surface of the rod-shaped member 20 is inclined with respect to the central axis of the rod-shaped member 20. A plurality of stripe-shaped grooves (hereinafter referred to as “oblique grooves”) 21 may be provided. The oblique groove 21 can be formed by machining, for example.

  9A to 9C show examples of the cross-sectional shape of the oblique groove 21. FIG. The cross section of the oblique groove 21 may be triangular as shown in FIG. 9A, or may be curved as shown in FIG. 9B. Further, the cross section of the oblique groove 21 may be trapezoidal (or rectangular) as shown in FIG.

  10A and 10B, the oblique groove 21 is set so that the angle θ (see FIG. 8) between the case where the oblique groove 21 is not provided and the direction perpendicular to the central axis of the rod-shaped member 20 is 30 °. The relationship between the load and the sensor sensitivity is shown for the case where is provided. As shown in FIG. 9A, the oblique groove 21 is provided with a triangular cross section, a depth d of 0.2 mm, and an apex angle θ ′ of 90 °. In the graphs of FIGS. 10A and 10B, the load in the compression direction is shown as a positive value, and the load in the tensile direction is shown as a negative value. The sensor sensitivity here is the ratio (ΔZ / Z0) of the impedance change amount ΔZ to the initial impedance Z0 of the sensor component.

  When the oblique groove 21 is not provided, as shown in FIG. 10A, the impedance changes greatly with increasing load (ΔZ is large and ΔZ / Z0 is large) as shown in FIG. The impedance does not change so much as the load increases (ΔZ is small and ΔZ / Z0 is also small). That is, when the oblique groove 21 is not provided, the sensitivity to the pulling force is lower than the sensitivity to the compressive force.

  On the other hand, when the oblique groove 21 is provided, as shown in FIG. 10 (b), the impedance changes to approximately the same as the load increases in both the compression direction and the pulling direction (ΔZ is approximately the same). Therefore, ΔZ / Z0 is about the same). That is, when the oblique groove 21 is provided, the sensitivity to the compressive force and the sensitivity to the pulling force can be made substantially the same. Moreover, it can be seen from the comparison between FIG. 10A and FIG. 10B that the nonlinearity and hysteresis of the sensor sensitivity are improved.

  As described above, by providing the oblique groove 21, the compression sensitivity and the tensile sensitivity can be equalized. The reason why the compression sensitivity and the tensile sensitivity are greatly different when the oblique grooves 21 are not provided, and the reason why these can be equalized by providing the oblique grooves 21 are not clear but are presumed as follows.

  FIG. 11 shows a resultant vector 20D in the magnetization direction of the rod-shaped member 20 when the oblique groove 21 is not provided. FIG. 11 also shows the flow of magnetic flux in the magnetic circuit. The resultant vector 20D in the magnetization direction of the rod-shaped member 20 is slightly inclined with respect to the central axis of the rod-shaped member 20, as shown in FIG. When the rod-shaped member 20 is extended by a pulling force, the resultant vector 20D in the magnetization direction changes so that the angle formed with the central axis of the rod-shaped member 20 becomes smaller. Further, when the rod-shaped member 20 is contracted by the compressive force, the resultant force vector 20D in the magnetization direction changes so that the angle formed with the central axis of the rod-shaped member 20 becomes larger. Since the resultant force vector 20D in the magnetization direction is originally substantially parallel to the central axis of the rod-shaped member 20, the case where a compressive force is applied to the rod-shaped member 20 is greater than the case where a tensile force is applied to the rod-shaped member 20. The resultant vector 20D in the magnetization direction is likely to change greatly, and the magnetic resistance is also likely to change greatly. Therefore, if the oblique groove 21 is not provided, a large difference occurs between the compression sensitivity and the tensile sensitivity, and the tensile sensitivity is lower than the compression sensitivity.

  FIG. 12 shows a resultant vector 20D in the magnetization direction of the rod-shaped member 20 when the oblique groove 21 is provided. The resultant force vector 20 </ b> D <b> 1 in the magnetization direction inside the rod-shaped member 20 is slightly inclined with respect to the central axis of the rod-shaped member 20. On the other hand, the magnetization direction 20D2 on the surface of the rod-shaped member 20 is parallel to the extending direction of the oblique grooves 21, and is different from the resultant vector 20D1 of the magnetization direction inside. Therefore, the resultant force vector 20D in the magnetization direction of the entire rod-shaped member 20 is defined by both the resultant magnetization vector 20D1 in the magnetization direction inside and the magnetization direction 20D2 in the surface, but due to the positional relationship with the magnetic circuit forming member 30, the circuit Since the magnetic resistance is more easily affected by the surface than the inside of the rod-shaped member 20, the resultant force vector 20 </ b> D of the magnetization direction of the entire rod-shaped member 20 is close to the magnetization direction 20 </ b> D <b> 2 on the surface of the rod-shaped member 20. Therefore, if the oblique groove 21 is formed so that the magnetization direction 20D2 on the surface of the rod-shaped member 20 is greatly inclined with respect to the central axis, the resultant vector 20D of the magnetization direction of the entire rod-shaped member 20 is set to the central axis of the rod-shaped member 20. Can be greatly inclined. Therefore, the magnitude of the change in the resultant vector 20D in the magnetization direction caused by the expansion / contraction of the rod-shaped member 20 is made approximately the same when the compressive force is applied to the rod-shaped member 20 and when the tensile force is applied. It becomes possible.

  As described above, by providing the oblique groove 21, the compression sensitivity and the tensile sensitivity can be equalized, and both the compression force and the tensile force can be suitably detected. In addition, the sensor sensitivity can be increased by setting the angle θ of the oblique groove 21 (angle formed with the direction orthogonal to the central axis) to an appropriate range. FIG. 13A shows the relationship between the angle θ of the oblique groove 21 and the sensor sensitivity. FIG. 13A shows the compression sensitivity, the tensile sensitivity, and the total (“sensitivity sum”) when a load of 300 N is applied to the rod-shaped member 20 as the sensor sensitivity. The ratio (compression sensitivity / tensile sensitivity) is also shown.

  As can be seen from FIG. 13A, all of the compression sensitivity, the pull sensitivity, and the total sensitivity increase as the angle θ of the oblique groove 21 increases, and decrease when the angle θ exceeds 35 °. That is, all of the compression sensitivity, the tensile sensitivity, and the total sensitivity have a peak around 35 °. The graph shown in FIG. 13A is shown in FIG. From the viewpoint of suitably detecting the compressive force and the tensile force, the total sensitivity is preferably 0.20 or more. As can be seen from FIG. 13B, when the angle θ of the oblique groove 21 is 14.2 ° or more and 65.5 ° or less, the total sensitivity can be 0.20 or more.

  Here, the structure in which the groove 21 is provided on the surface of the rod-shaped member 20 is illustrated, but means for imparting a shape magnetic anisotropy different from the inside to the surface of the rod-shaped member 20 is limited to the groove 21. is not. For example, as shown in FIG. 14A, a striped plating pattern 22 extending in a direction inclined with respect to the central axis of the rod-shaped member 20 may be formed on the surface of the rod-shaped member 20. The plating pattern 22 is composed of a plurality of plating layers 22 a, and each plating layer 22 a extends in a direction inclined with respect to the central axis of the rod-shaped member 20. The plating layer 22 a is formed from a magnetic material different from the material of the rod-shaped member 20. Alternatively, the rod-shaped member 20 may be formed from a nonmagnetic material, and a plating layer 22a formed from a magnetic material may be provided on the surface thereof.

  Alternatively, as shown in FIG. 14B, a plurality of striped magnetic strips 23 extending in a direction inclined with respect to the central axis of the rod-shaped member 20 may be attached to the surface of the rod-shaped member 20. Each magnetic ribbon 23 is formed of a magnetic material different from the material of the rod-shaped member 20. Alternatively, the rod-shaped member 20 may be formed from a nonmagnetic material, and a magnetic ribbon 23 formed from a magnetic material may be attached to the surface thereof.

  Even when the plating pattern 22 as shown in FIG. 14A or the magnetic ribbon 23 as shown in FIG. 14B is provided on the surface of the rod-shaped member 20, the magnetization direction on the surface of the rod-shaped member 20 is Since it coincides with the extending direction of the plating pattern 22 and the magnetic ribbon 23, the same effect as the case where the groove 21 is provided can be obtained. Similarly to the case where the groove 21 is provided, when the plating pattern 22 and the magnetic ribbon 23 form an angle of 14.2 ° or more and 65.5 ° or less with the direction orthogonal to the central axis of the rod-shaped member 20, The sum of the compression sensitivity and the tensile sensitivity can be increased (specifically, 0.20 or more).

  As described above, when shape magnetic anisotropy is imparted to the surface of the rod-shaped member 20 by providing the groove 21, the plating pattern 22, and the magnetic ribbon 23 extending in a direction inclined with respect to the central axis of the rod-shaped member 20, When a torsional stress is applied to the rod-shaped member 20, the impedance changes and the sensor output fluctuates in the same manner as when a compressive force or a tensile force is applied. Therefore, the structure capable of preventing the application of torsional stress as illustrated in FIGS. 4 to 6 is particularly effective when the oblique groove 21 or the like is provided on the surface of the rod-shaped member 20.

  Next, another example of a more specific structure of the magnetostrictive load sensor 100 in the present embodiment will be described with reference to FIGS.

  In the load sensor 100a shown in FIG. 3, the connecting members 61 and 62 are provided at both ends thereof, but the connecting members are not necessarily provided at both ends. Further, in the load sensor 100a shown in FIG. 3, the load transmitting members 40 and 42 are coupled to both ends of the rod-shaped member 20, but it is necessary to provide load transmitting members corresponding to both ends of the rod-shaped member 20. There is no.

  A magnetostrictive load sensor 100b shown in FIG. 15 is different from the load sensor 100a shown in FIG. 3 in that the connecting member 62 is provided only at one end thereof. The end of the load sensor 100 b where the connecting member is not provided (here, the end of the housing 50) is fixed to the movable body 1. In this configuration, the housing 50 and the receiving member 41 do not transmit a load to the one end 20 a of the rod-shaped member 20. That is, the housing 50 and the receiving member 41 do not function as a load transmission member. Therefore, the load sensor 100b is different from the load sensor 100a shown in FIG. 3 in that the load transmission member 42 is coupled only to the other end 20b of the rod-shaped member 20. As described above, even when the housing 50 is installed on the movable body 1, the load sensor 100 b can suitably detect the compressive force and the tensile force.

  Further, the structure for limiting the position of the rod-shaped member 20 is not limited to the structure illustrated in FIG. In the magnetostrictive load sensor 100c shown in FIGS. 16 (a) and 16 (b), the housing 50 has a concave portion 50b that fits into one end portion (not the large diameter portion) 20a of the rod-shaped member 20, and has a rod shape. Position restriction is performed by joining one end 20 a of the member 20 to the housing 50. That is, in the load sensor 100a shown in FIG. 3, the housing 50 and the receiving member 41 cooperatively function as the restricting member on the one end portion 20a side of the rod-like member 20, whereas in the load sensor 100c shown in FIG. On the one end 20a side of the member 20, only the housing 50 functions as a limiting member. The housing 50 also functions as a load transmission member that transmits a load applied to the connecting member 61 to the one end 20 a of the rod-shaped member 20. The joining of the one end portion 20a of the rod-shaped member 20 to the housing 50 is performed by, for example, screwing, bonding, or press fitting. When joining by screwing, the external thread portion formed at the one end portion 20a of the rod-shaped member 20 is a deformed portion having a different outer peripheral shape from the other portions, and the internal thread portion formed in the recess 50b of the housing 50 is It is a latching | locking part which latches the external thread part which is a deformed part.

  In the load sensor 100c shown in FIG. 16, the load transmission member 42 includes a coupling portion that is rotatably coupled to the other end portion 20b of the rod-shaped member 20. Hereinafter, this structure will be described more specifically with reference to FIG. FIG. 17 is an enlarged view showing the vicinity of the other end 20b of the rod-shaped member 20 in the load sensor 100c.

  The other end 20 b of the rod-shaped member 20 is a large-diameter portion having a larger outer diameter than the central portion of the rod-shaped member 20. The load transmission member 42 of the load sensor 100c is connected to the receiving member 48 that contacts the other end portion (large diameter portion) 20b of the rod-shaped member 20 and the large diameter portion 20b of the rod-shaped member 20 and the connecting member 62. And a member 44.

  The connecting member 44 is coupled to the connecting member 62 at one end thereof. The connecting member 44 has a space S <b> 3 for accommodating the large-diameter portion 20 b of the rod-shaped member 20 and the receiving member 48 therein.

  The receiving member 48 has a substantially columnar shape, and has a concave portion 48a on one end face (end face on the rod-like member 20 side). The recess 48 a of the receiving member 48 is engaged with the large diameter portion 20 b of the rod-shaped member 20.

  Further, the connecting member 44 has a locking portion 44a that locks the end surface (end surface opposite to the receiving member 48) 20b1 of the large-diameter portion 20b of the rod-shaped member 20. The large-diameter portion 20b of the rod-shaped member 20 is sandwiched between the receiving member 48 and the engaging portion 44a of the connecting member 44, and thereby the large-diameter portion 20b of the rod-shaped member 20 and the load transmitting member 42 are coupled. ing. As shown in FIG. 17, the end surface 20 b 2 on the receiving member 48 side of the large diameter portion 20 b has a substantially spherical shape and is in contact with the bottom surface 48 a 1 of the recess 48 a of the receiving member 48. A predetermined gap is provided between the outer peripheral surface 20b3 of the large-diameter portion 20b and the inner peripheral surface 48a2 of the recess 48a.

  When the other end portion 20b of the rod-shaped member 20 and the load transmitting member 42 are coupled with each other as described above, the rod-shaped member 20 can rotate when an external force that twists the rod-shaped member 20 is applied. As described above, the load transmission member 42 of the load sensor 100c includes a coupling portion (receiving member 48) that is rotatably coupled to the other end portion 20b of the rod-shaped member 20a. Therefore, it is possible to prevent the torsional stress from being applied to the rod-shaped member 20. Therefore, it is possible to prevent irreversible damage and plastic deformation from being applied to the rod-shaped member 20 due to twisting, and the reliability is further improved.

  In the configuration shown in FIG. 16, the connection member 44 and the housing 50 also function as a limiting member on the other end 20 b side of the rod-shaped member 20. The connection member 44 includes two large diameter portions 44b and 44c having a relatively large outer diameter. One large diameter portion 44b is located in the housing 50, and the housing 50 has a locking portion 50b for locking the large diameter portion 44b. The other large diameter portion 44c is located outside the housing 50, and the one end portion 50c of the housing 50 functions as a locking portion for locking the large diameter portion 44c. Although predetermined gaps are provided between the locking portion 50b and the large diameter portion 44b and between the locking portion 50c and the large diameter portion 44c, an excessive tensile load is applied to the load transmitting member 42 from the outside. When added, the large diameter portion 44b is brought into contact with the locking portion 50b and locked. Further, when an excessive compressive load is applied to the load transmission member 42 from the outside, the large diameter portion 44c comes into contact with and is locked with the locking portion 50c.

  A mechanism for preventing the torsional stress from being applied to the rod-shaped member 20, that is, a mechanism for connecting the load transmitting member to the rod-shaped member 20 so as to be rotatable (referred to as “escape mechanism”) is shown in FIGS. The structure is not limited to the above. 18 (a) and 18 (b) show another magnetostrictive load sensor 100d including a relief mechanism.

  One end portion 20a of the rod-shaped member 20 included in the load sensor 100d is a large-diameter portion having an outer diameter larger than that of the central portion, and is rotatably coupled to the load transmission member 40 by a structure similar to the structure shown in FIG. ing.

  Further, the other end 20 b of the rod-shaped member 20 is coupled to a load transmission member 42 including a first connection member 45, a second connection member 46, and a third connection member 47. The structures of the first connection member 45, the second connection member 46, and the third connection member 47 will be described more specifically with reference to FIGS.

  The first connecting member 45 has a substantially cylindrical shape, and has large-diameter portions 45a and 45a 'having relatively large outer diameters and small-diameter portions 45b having relatively small outer diameters. The large-diameter portion 45a is formed with a hole 45c extending in the central axis direction of the load sensor 100d and a through hole 45d extending in a direction orthogonal to the central axis. The hole 45c and the through hole 45d are joined on the way as shown in FIG.

  The second connecting member 46 has a substantially columnar shape, and includes a large diameter portion 46a having a relatively large outer diameter and a small diameter portion 46b having a relatively small outer diameter. A through hole 46c extending in the central axis direction of the load sensor 100d is formed in the second connection member 46 over both the large diameter portion 46a and the small diameter portion 46b. On the inner peripheral surface of the through hole 46c, a female screw portion that is screwed with a male screw portion (not shown in FIG. 15) formed on the other end portion 20b of the rod-like member 20 is provided. That is, the through hole 46 c is a screw hole that is screwed into the other end portion 20 b of the rod-shaped member 20.

  The third connection member 47 has a rod shape (more specifically, a substantially columnar shape), and the third connection member 47 is formed with a through hole 47a extending in the central axis direction of the load sensor 100d. A part 47 a 1 of the through hole 47 a is a hole that fits into the small diameter part 46 b of the second connection member 46, and the other part 47 a 2 is a screw hole that engages with the other end part 20 b of the rod-like member 20.

  The 1st connection member 45, the 2nd connection member 46, the 3rd connection member 47, and the rod-shaped member 20 are couple | bonded in the following procedures. First, as shown in FIG. 21A, the third connection member 47 is inserted into the through hole 45 d of the first connection member 45. That is, the third connection member 47 is a rod-like member extending in a direction intersecting with the central axis of the rod-like member 20, and the first connection member 45 is a through-hole into which the third connection member (rod-like member) 47 is inserted. This is a housing member having a hole 45d. Next, as shown in FIG. 21 (b), the second connecting member 46 is screwed deeply into the rod-shaped member 20.

  Subsequently, as shown in FIG. 22A, the rod-like member 20 is screwed into the screw hole 47 a 2 of the third connection member 47 so that the tip does not protrude from the third connection member 47. Thereafter, as shown in FIG. 22B, the second connecting member 46 is screwed in until the small diameter portion 46 b is fitted into the hole 47 a 1 of the third connecting member 47. In this way, the load transmitting member 42 and the other end 20b of the rod-shaped member 20 are coupled. A load is transmitted between the outer peripheral surface 47 b of the third connecting member (bar-shaped member) 47 and the inner peripheral surface 45 d 1 of the through hole 45 d of the first connecting member (housing member) 45.

  Here, the inner diameter Di1 of the through hole 45d of the first connection member 45 is larger than the diameter Di2 of the third connection member 47 by a predetermined value (see FIG. 20). That is, a predetermined gap is provided between the outer peripheral surface 47 b of the third connection member 47 and the inner peripheral surface 45 d 1 of the through hole 45 d of the first connection member 45. Therefore, when torsional stress is applied, as schematically shown in FIG. 23, the second connecting member 46 and the third connecting member 47 screwed to the other end 20b are twisted. It can be rotated somewhat in the direction (left-right direction in FIG. 23). Further, the rod-shaped member 20 can rotate with respect to the third connecting member 47 by screwing or screwing in the screw hole 47 a 2. Therefore, it is possible to prevent torsional stress from being applied to the rod-shaped member 20 and to prevent occurrence of a steady output error due to torsion.

  Moreover, the clearance gap between the 3rd connection member 47 and the 1st connection member 45 is provided about all the radial directions of the through-hole 45d so that FIG. 23 may also show. Therefore, the third connecting member 47 is allowed to rotate in directions other than the twist direction (for example, the vertical direction in FIG. 23). Therefore, stress concentration due to bending or coaxial displacement can be avoided, and sensor output fluctuations due to such stress concentration can be prevented.

  Alternatively, at least one of the connecting members 61 and 62 may have a relief mechanism. For example, by providing spherical sliding bearings on the annular members 61b and 62b of the connecting members 61 and 62, the connecting members 61 and 62 including an escape mechanism are obtained. As the connecting members 61 and 62 including spherical sliding bearings, for example, members commercially available under the name “rod end” can be used.

(Load detection circuit using magnetostrictive load sensor)
A configuration of a load detection circuit using a magnetostrictive load sensor will be described with reference to FIG. FIG. 24 is a block diagram showing a schematic configuration of a load detection circuit 600 using the magnetostrictive load sensor 100. The load sensor 100 may be a load sensor 100a, 100b, 100c, or 100d.

  The load detection circuit 600 includes an oscillation circuit 610, a magnetostrictive load sensor 100, a temperature compensation resistance circuit 620, current detectors 630A and 630B, rectification circuits 650A and 650B, and an amplification circuit 670.

  The oscillation circuit 610 provides an oscillation signal to one end of the coil A of the magnetostrictive load sensor 100 and one end of the temperature compensation resistance circuit 620. The magnetostrictive load sensor 100 detects an external load. The current detector 630A converts a current supplied from the other end of the coil A of the magnetostrictive load sensor 100 into a voltage. The current detector 630B converts a current supplied from the other end of the temperature compensation resistor circuit 620 into a voltage. The rectifier circuit 650A rectifies and smoothes the voltage output from the current detector 630A. The rectifier circuit 650B rectifies and smoothes the voltage output from the current detector 630B. The amplifier circuit 670 amplifies the difference between the output voltage of the rectifier circuit 650A and the output voltage of the rectifier circuit 650B.

  When the load applied between the load transmitting members Da and Db in FIG. 1 is transmitted to both ends of the rod-shaped member B and a compressive force or a pulling force acts on the load detecting member B, the magnetic permeability of the load detecting member B is caused by the inverse magnetostrictive effect. Changes, and the impedance of the sensor component composed of the coil A, the load detection member B, and the magnetic circuit forming member C changes. An output signal corresponding to this impedance change is obtained by the amplifier circuit 670. In this way, the load can be detected electromagnetically.

  An output signal of the amplification circuit 670 of the load detection circuit 600 is given to the control unit 680. The control unit 680 includes a CPU (Central Processing Unit) and a RAM (Random Access Memory). The CPU operates according to a control program stored in the RAM. The control unit 680 performs a predetermined calculation on the output signal of the amplifier circuit 670 and gives a control signal based on the calculation result to the actuator 690. Actuator 690 generates a driving force in response to the control signal.

(Shift load detector using magnetostrictive load sensor)
With reference to FIG. 25, the configuration of a shift load detection apparatus using a magnetostrictive load sensor will be described. FIG. 25 is a diagram schematically showing a shift load detection device 700 using the magnetostrictive load sensor 100a.

  The shift load detection device 700 is provided in the vicinity of the internal combustion engine 712 of the motorcycle. The shift load detection device 700 includes a shift shaft 713 protruding from a gear box (not shown), a shift rod 715 coupled to the shift shaft 713, and a shift pedal 714 for the rider to perform a shift change. The shift pedal 714 is provided so as to be swingable about the support shaft 714a, and is pushed up or down by the rider's foot (supported by the step 717). The connecting member 61 at one end of the load sensor 100a is connected to the shift pedal 714, and the connecting member 62 at the other end of the load sensor 100a is connected to the shift rod 715, so that the shift pedal 714 and the shift rod 715 Are connected via a load sensor 100a.

  By detecting the shift load by the load sensor 100a that can detect both the compressive force and the tensile force, it can be determined whether or not the shift change has been performed reliably. Generally, when a shift change is successful, a load decrease is observed during the shift operation. On the other hand, when the shift change fails, the load does not decrease until the shift operation is released. Accordingly, by detecting the shift load, it is possible to determine whether or not the shift change is successful.

  The magnetostrictive load sensors 100a, 100b, 100c, and 100d described above are not limited to motorcycles, but are used in various transportation equipment such as planing boats, electric bicycles, water bikes, and electric wheelchairs. Moreover, it is used not only for transport equipment but also for mobile shelves. That is, the magnetostrictive load sensors 100a, 100b, 100c and 100d are widely used for all moving objects.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used for detecting loads on various moving objects such as motorcycles, planing boats, electric bicycles, water bikes, electric wheelchairs, and moving shelves.

A, 10 Coil B, 20 Load detection member (bar-shaped member)
C, 30 Magnetic circuit forming member Da, Db, 40, 42 Load transmitting member E, 50 Housing 45 First connecting member 46 Second connecting member 47 Third connecting member 57 Elastic member 61, 62 Connecting member 100, 100a , 100b Magnetostrictive load sensor 100c, 100d Magnetostrictive load sensor 600 Load detection circuit 700 Shift load detection device

Claims (14)

A coil having a through hole;
A load detection member inserted into the through hole;
A magnetic circuit forming member for forming a magnetic circuit through which a magnetic flux generated by a current flowing through the coil passes, and extending from the first portion to the outside of the magnetic circuit. A magnetic circuit forming member having a provided second portion;
A load transmitting member that transmits a compressive load and a tensile load applied from the outside to the load detecting member;
A limiting member that limits relative change in the position of the load detection member along the direction of the central axis with respect to the magnetic circuit forming member to a range where the load transmitting member does not contact the first portion of the magnetic circuit forming member. and, with a,
The load transmission member includes a coupling portion rotatably coupled to the load detection member,
A magnetostrictive load sensor in which an end surface of the load detection member that contacts the coupling portion or an end surface of the coupling portion that contacts the load detection member has a substantially spherical shape .   The magnetostrictive load sensor according to claim 1, wherein the limiting member is provided outside a magnetic circuit. The load detection member or the load transmission member has a deformed portion having a different outer peripheral shape from other portions of the member,
The magnetostrictive load sensor according to claim 1, wherein the limiting member has a locking portion that locks the deformed portion.   4. The magnetostrictive load sensor according to claim 1, wherein a surface of the load detection member has a shape magnetic anisotropy different from an inside of the load detection member. 5.   The surface of the load detection member has a plurality of stripe-shaped grooves extending in a direction inclined with respect to the central axis of the load detection member, and a striped plating pattern extending in a direction inclined with respect to the central axis of the load detection member The magnetostrictive load sensor according to claim 4, further comprising a plurality of stripe-shaped magnetic ribbons extending in a direction inclined with respect to a central axis of the load detection member.   6. The magnetostriction according to claim 5, wherein the plurality of grooves, the plating pattern, or the plurality of magnetic ribbons form an angle of 14.2 ° or more and 65.5 ° or less with a direction orthogonal to a center axis of the load detection member. Type load sensor.   The magnetostrictive load sensor according to claim 6, wherein the plurality of grooves, the plating pattern, or the plurality of magnetic ribbons form an angle of 35 ° with a direction orthogonal to a central axis of the load detection member. A coil having a through hole;
A load detection member inserted into the through hole;
A magnetic circuit forming member for forming a magnetic circuit through which a magnetic flux generated by a current flowing through the coil passes, and extending from the first portion to the outside of the magnetic circuit. A magnetic circuit forming member having a provided second portion;
A load transmitting member that transmits a compressive load and a tensile load applied from the outside to the load detecting member;
A limiting member that limits relative change in the position of the load detection member along the direction of the central axis with respect to the magnetic circuit forming member to a range where the load transmitting member does not contact the first portion of the magnetic circuit forming member. And comprising
The load transmission member includes a coupling portion rotatably coupled to the load detection member,
The coupling portion is a receiving member that comes into contact with one end of the load detection member,
The load transfer member further said receiving elastic member including magnetostrictive load sensor to be biased to the load detection member side member. Magnetostrictive load sensor according to any of claims 1 to 8 including a relief mechanism for rotatably coupling said load transfer member to the load detection member. A coil having a through hole;
A load detection member inserted into the through hole;
A magnetic circuit forming member for forming a magnetic circuit through which a magnetic flux generated by a current flowing through the coil passes, and extending from the first portion to the outside of the magnetic circuit. A magnetic circuit forming member having a provided second portion;
A load transmitting member that transmits a compressive load and a tensile load applied from the outside to the load detecting member;
A limiting member that limits relative change in the position of the load detection member along the direction of the central axis with respect to the magnetic circuit forming member to a range where the load transmitting member does not contact the first portion of the magnetic circuit forming member. And comprising
Including a relief mechanism that rotatably couples the load transmission member to the load detection member;
The escape mechanism includes a rod-shaped member extending in a direction intersecting with the central axis of the load detection member, and a housing member having a through hole into which the rod-shaped member is inserted,
The inner diameter of the through hole is larger than the outer diameter of the rod-shaped member,
Magnetostrictive load sensor load Ru is transmitted between the outer peripheral surface and the inner peripheral surface of the through hole of the accommodation member of the bar-like member. The magnetostrictive load sensor according to any one of claims 1 to 10 , further comprising a connecting member that is directly or indirectly coupled to the load transmitting member and connects the magnetostrictive load sensor to the outside. The magnetostrictive load sensor according to claim 11 , wherein the connecting member includes a spherical sliding bearing. A housing for accommodating the coil, the load detection member, and the magnetic circuit forming member;
The housing magnetostrictive load sensor according to any one of claims 1 to 12, wherein the magnetic circuit forming members for fixing of holding the second portion. Moving body provided with a magnetostrictive load sensor according to any of claims 1 13.

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