JP2014130035A - Stroke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroke sensor capable of detecting an accurate amount of stroke by improving assemblability and productivity, and using a hard material that can be quenched.SOLUTION: A stroke sensor 1 detects an amount of movement of a detection object, and includes a first unit 2 having a quenched shaft 3 formed of a magnetic material, a magnet 4 which is formed integrally with the shaft 3 and arranged in a holder 15 of a non-magnetic material, an elastic member 5 for elastically energizing the shaft 3 to the detection object, and a first case body 7 for supporting the shaft 3 and elastic member 5; and a second unit 8 having a circuit board 10 for mounting a magnetic detection element which detects a magnetic field of the magnet 4, and a second case body 13 for supporting the magnetic detection element and the circuit board 10. The second unit 8 is accommodated in the first unit 2.

Description

  The present invention relates to a stroke sensor that detects the amount of movement of an object to be detected.

  A conventional stroke sensor is disclosed in Patent Document 1, for example. The stroke sensor includes a first case having a sliding hole, a second case constituting an oil chamber filled with oil between the first case and the first case by being coupled to the first case. The oil passage formed in the communication chamber is connected to the outside and the sliding hole of the first case is movably fitted in the sliding hole of the first case with the tip portion exposed to the outside. A shaft that accommodates a flange having a large diameter, a pressure spring that is disposed in the oil chamber and presses the tip of the shaft in a direction that always protrudes from the first case, and a displacement amount of the shaft outside the second case And a Hall element that outputs an electrical signal according to the above.

  However, in the stroke sensor described in Patent Document 1, a shaft is disposed at the approximate center of a cylindrical first case, a magnet is disposed coaxially with the shaft, and the upper or lower side of the magnet, so-called first. Each component must be stacked and assembled such that a circuit board equipped with a Hall IC is positioned so as to be located outside the radial direction of the case, and further improvement in productivity is desired. Have.

  As a solution to such a problem, the applicant of the present application has proposed in Japanese Patent Application No. 2012-191211. This stroke sensor is a stroke sensor that detects the amount of movement of a magnet provided on a shaft that moves as the object to be detected moves. An elastic member that urges the shaft in the longitudinal direction of the shaft, and the shaft and the elastic member are arranged. First case body, a first unit including a shaft, an elastic member, and a first case body, a magnetic detection element for detecting a magnetic field of a magnet, a circuit board on which the magnetic detection element is mounted, and a magnetic detection element And a second case body in which the circuit board is disposed, and a second unit including the magnetic detection element, the circuit board, and the second case body, and the first and second case bodies are formed in a cylindrical shape, The second unit is incorporated in the first unit, and the assembling property can be improved and the productivity can be improved.

JP 2010-210493 A

  However, the stroke sensor described above forms a shaft with a non-magnetic material such as brass or stainless steel, and is a material that cannot be hardened for the purpose of making it hard, so that it operates in contact with the object to be detected. If this is repeatedly performed, the contact portion of the shaft is worn and the stroke amount is changed, so that it is difficult to accurately detect the stroke amount with time.

  In order to solve this problem, the shaft needs to be made of a hard material and further hardened. However, since such a material is a magnetic material, the magnetic circuit of the magnet is disturbed by the shaft, and the magnetic detection element There is a problem that an accurate magnetic change, that is, a stroke amount cannot be detected.

  Therefore, the present invention solves the above-mentioned problems, improves the assemblability, improves the productivity, and can use a hard material that can be hardened on the shaft, thereby enabling accurate detection of the stroke amount. The object is to provide a stroke sensor.

  In order to solve the above-described problems, the present invention provides a stroke sensor that detects the amount of movement of a magnet provided on a shaft that moves in accordance with the movement of a detected object. The shaft where the contact portion is at least quenched, a holder portion made of a non-magnetic material that is located on a side opposite to the contact portion of the shaft and is provided integrally with the shaft, and the holder A magnet disposed in a portion, an elastic member that elastically urges the shaft toward the detected body along the longitudinal direction of the shaft, and a first case body that supports the shaft and the elastic member , A magnetic detection element that detects the magnetic field of the magnet, a circuit board on which the magnetic detection element is mounted, and the magnetic detection element and the circuit board. A second unit including at least a second case body, wherein the first and second case bodies are formed in a cylindrical shape, and the second unit is incorporated into the first unit. It is a stroke sensor characterized by these. By configuring in this way, it is possible to maintain a state where the hardness of the shaft is increased, and therefore, even if the operation in which the shaft is brought into contact with the detection object is repeatedly performed, the wear of the contact portion of the shaft is dramatically increased. It is possible to suppress the disturbance of the magnetic field of the magnet received by the magnetic detection element through the holder portion made of a non-magnetic material, and a stable stroke amount can be detected.

  According to a second aspect of the present invention, in the stroke sensor according to the first aspect, the surface of the shaft is plated. By comprising in this way, since the shaft is plated, even if it uses a magnetic body material, it is rich in rust prevention property and can maintain durability performance.

  According to a third aspect of the present invention, in the stroke sensor according to the first or second aspect, the holder portion has an opening that exposes at least a part of the magnet, and the magnetic detection element extends from the opening. It is arranged to face the exposed magnet portion. With this configuration, the magnet is provided so that a part of the magnet is exposed from the opening portion provided in the holder portion, so that the distance between the outer peripheral end surface of the magnet and the package end surface of the magnetic detection element can be reduced. Further miniaturization can be realized, the magnetic flux density from the magnet received by the magnetic detection element is increased, and the external magnetic field resistance can be improved.

  In the present invention, in the stroke sensor for detecting the movement amount of the magnet provided on the shaft that moves along with the movement of the detected object, the stroke sensor is made of a magnetic material, and at least the contact portion with the detected object is quenched. A shaft, a holder portion made of a non-magnetic material provided integrally with the shaft, on a side opposite to the contact portion portion of the shaft, the magnet disposed in the holder portion, and the shaft A first unit comprising at least a resilient member that elastically biases the shaft toward the detected body side along the longitudinal direction, and a first case body that supports the shaft and the resilient member, and the magnet A magnetic detection element for detecting a magnetic field of the magnetic detection element, a circuit board on which the magnetic detection element is mounted, and a second case body for supporting the magnetic detection element and the circuit board. And a second unit provided with the first, the second case member is formed into a cylindrical shape, a stroke sensor, wherein the second unit is incorporated into the first unit. By configuring in this way, it is possible to maintain a state where the hardness of the shaft is increased, and therefore, even if the operation in which the shaft is brought into contact with the detection object is repeatedly performed, the wear of the contact portion of the shaft is dramatically increased. It is possible to reduce the disturbance of the magnetic field of the magnet that the magnetic detection element receives through the holder part made of a non-magnetic material, and to detect a stable stroke amount. It is possible to provide a stroke sensor that can be achieved, can improve assembly, and can improve productivity.

Sectional drawing of the stroke sensor which shows the 1st Embodiment of this invention. Sectional drawing of the 1st unit of the embodiment. Sectional drawing of the shaft of the embodiment. Sectional drawing of the 2nd unit of the embodiment. The rear view of the 2nd unit which is not filled with the filler of the embodiment. Sectional drawing of the 1st unit which is other embodiment of this invention. Sectional drawing of the shaft which is other embodiment of this invention. Sectional drawing of the stroke sensor which is other embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The stroke sensor 1 according to the embodiment of the present invention includes two units, a first unit 2 and a second unit 8. In addition, L1 is an axis | shaft which the shaft 3 mentioned later of the stroke sensor 1 moves.

  The shaft 3 is made of an iron-based material such as columnar carbon steel or chrome molybdenum steel, and a detection target (not shown) and a contact portion 3a on the tip end side of the shaft 3 come into contact with each other, and the longitudinal direction of the shaft 3 ( It moves along the axis L1). In addition, the thing which performed the quenching process and the nitriding process as a wear-resistant improvement means is good, and surface treatments, such as plating, are given in order to improve rust prevention and a slip.

  The shaft 3 is located on the side opposite to the contact portion 3a of the shaft 3, and the rear end portion 3b of the shaft 3 (on the right side in FIGS. 1 to 3) is provided with a holder portion 15 made of a non-magnetic material. The magnet 4 is integrally held by outsert or insert molding.

  In the present configuration (FIG. 3) using the shaft 3 made of a soft magnetic material through the holder portion 15 made of a non-magnetic material, the magnetic detection element described in Japanese Patent Application No. 2012-191212 previously proposed by the applicant of the present application. Can be set to a state close to the case where the periphery of the magnet is directly covered with a non-magnetic shaft, so that the detection function as a sensor can be maintained and the hard material (carbon Steel, chrome molybdenum steel, etc.).

  Moreover, as shown in FIG. 7, the structure which shape | molds the holder part 15 by aligning so that the rear-end part 3b of the shaft 3 and the end surface 4a of the magnet 4 may contact | adopt is employ | adopted. With this arrangement, the positional relationship of the magnet 4 with respect to the shaft 3 can be set at a predetermined position, and the arrangement position with the magnetic detection element can be easily adjusted to the predetermined position. At this time, even if the rear end portion 3b of the shaft 3 which is a soft magnetic material and the end face 4a of the magnet 4 are in contact with each other, the other end face 4b of the magnet 4 is open, so that the area received by the magnetic detection element is sufficient. It is possible to generate a simple magnetic field.

  The rear end portion 3b side of the shaft 3 including the holder portion 15 and the magnet 4 is disposed in a first storage portion 13a provided in the second case body 13 described later.

  The shaft 3 includes a large-diameter portion 3c serving as a stopper portion on the slightly distal end side of the center portion. The large diameter portion 3 c is larger than the inner diameter of the first bearing portion 7 a of the first case body 7 and also serves as a receiving portion that comes into contact with the coil spring 5.

  Further, the shaft 3 is supported by a first bearing portion 7a of the first case body 7 so that the small diameter portion 3d on the tip side of the shaft 3 is movably supported by the large diameter portion 3c, and the rear side of the large diameter portion 3c. The middle diameter portion 3e is supported by the second bearing portion 6 (the inner diameter portion 6c) in a movable manner. In the present embodiment, the diameters of the small diameter portion 3d, the middle diameter portion 3e, and the large diameter portion 3c of the shaft 3 are small diameter portion 3d <mid diameter portion 3e <large diameter portion 3c.

  The coil spring 5 is provided between the large diameter portion 3 c and the second bearing portion 6, and the shaft 3 has the large diameter portion 3 c of the shaft 3 by the elasticity of the coil spring 5 and the first bearing portion 7 a. The shaft 3 is urged so as to abut on the abutting portion 7b provided on the shaft 3 to determine the initial position of the shaft 3.

  The shaft 3 includes two bearing portions 7a, a first bearing portion 7a provided in the first case body 7 and a second bearing portion 6 that is press-fitted and installed in a first storage portion 7c of the first case body 7 to be described later. A stroke can be made along the axis L <b> 1 by performing a linear motion in 6.

  In addition, when the inner diameter of the inner diameter part 6c of the second bearing part 6 is made smaller than the inner diameter of the first bearing part 7a, the locus where the shaft 3 is displaced in the direction other than the direction of the axis L1 is the second bearing part 6 as a fulcrum. Since it becomes a circular arc, blurring of the magnet 4 other than the direction of the axis L1 can be suppressed as compared with the case where the first bearing portion 7a is used as a fulcrum, and as a result, good output characteristics can be obtained.

  The magnet 4 is formed in a cylindrical shape and is made of a magnet such as an Nd—Fe—B permanent magnet or an SmCo magnet, and the magnetic pole is magnetized in the direction of the axis L1. The magnetizing direction may be one in which the magnetic pole is magnetized in a direction perpendicular to the direction of the axis L1.

  The magnet 4 strokes the inside of the 1st accommodating part 13a provided in the 2nd case body 13 mentioned later with the stroke motion (reciprocating motion) of the shaft 3.

  The holder 15 is made of a resin such as PPS or PBT, and serves to attach the magnet 4 to the shaft 3 and is formed integrally with the shaft 3 and the magnet 4 by outsert or insert molding.

  The coil spring 5, which is an elastic member, is made of, for example, a stainless steel material for a spring, is disposed around the diameter middle portion 3 e of the shaft 3, and is housed in the first housing portion 7 c of the first case body 7.

  Further, the coil spring 5 plays a role of determining an initial position by applying the large diameter portion 3c of the shaft 3 to the contact portion 7b of the first case body 7, and further, when the detected body and the shaft 3 come into contact with each other. Since the detected object is always urged and pressed, the displacement of the stroke amount due to vibration or the like can be suppressed.

  The second bearing portion 6 is made of brass, stainless steel, or the like and has an annular shape. Moreover, the 2nd bearing part 6 is comprised by the large diameter part 6a and the small diameter part 6b from which a diameter differs. The small-diameter portion 6b is press-fitted and held in the first housing portion 7c of the first case body 7, and the inner diameter portion 6c, which is a hole penetrating the second bearing portion 6, serves as a bearing mechanism, so that the shaft 3 can be stroked. It is supported (possible reciprocation). The inner diameter portion 6c is subjected to a surface treatment for improving the slidability such as plating or resin coating in order to improve the sliding.

  Further, the second bearing portion 6 is provided with a spring receiving portion 6d of the coil spring 5 in the small diameter portion 6b so that the shaft 3 is always urged forward by the elasticity of the coil spring 5, and comes into contact with the coil spring 5. The coil spring 5 is energized.

  The first case body 7 is made of a nonmagnetic metal, such as stainless steel, and mainly includes a first storage portion 7c and a second storage portion 7d.

  The 1st accommodating part 7c is a cylindrical shape provided with the 1st bearing part 7a used as a bottom part, and accommodates the shaft 3 and the coil spring 5. FIG. And in order to hold | maintain the shaft 3 and the coil spring 5, the 2nd bearing part 6 is press-fit in the 1st accommodating part 7c as a retaining. The first bearing portion 7 a of the first storage portion 7 c is a bearing for the small diameter portion 3 d of the shaft 3. The surface of the first bearing portion 7 a that faces the first storage portion 7 c is a contact portion 7 b that contacts the coil spring 5, contacts the large-diameter portion 3 c that is a stopper portion of the shaft 3, and the shaft 3. It plays a role in regulating movement.

  The second storage portion 7d of the first case body 7 has a cylindrical shape with a bottom portion 7e, and stores a second unit 8 described later. The first storage portion 7c is connected to the bottom portion 7e, and the first storage portion 7c is provided in the central portion of the bottom portion 7e. The bottom portion 7e of the second storage portion 7d abuts on the second unit 8, so that the second storage portion 7d receives the second unit 8 and at the open end of the second storage portion 7d of the first case body 7. As shown in FIG. 1, the caulking portion 7f provided is bent inward of the second storage portion 7d as shown in FIG. 1, so that the second unit 8 is inside the second storage portion 7d of the first case body 7. It is stored and held in.

  The first case body 7 includes an attachment portion 7g for mounting and fixing to the detected body. The mounting portion 7g is provided in a portion corresponding to at least the first bearing portion 7a and the second bearing portion 6 of the first case body 7, that is, a portion corresponding to the first storage portion 7c. It is provided on the outer peripheral surface of one storage portion 7c. The mounting portion 7g is provided with a thread of a male screw so that the mounting portion 7g becomes a male screw, and the stroke sensor 1 can be screwed.

  Since the coil spring 5 is housed in the mounting portion 7g of the first case body 7, that is, in the first housing portion 7c, the coil spring 5 can be reduced in size in the direction of the axis L1 of the shaft 3 of the stroke sensor 1. When the stroke sensor 1 is assembled, it is possible to reduce the amount of protrusion (projection) from the mounting surface of the stroke sensor 1.

  The second unit 8 is a unit composed of a magnetic detection package 9, a circuit board 10, an electric wire 11, a seal member 12, a second case body 13, and a filler 14.

  The magnetic detection package 9 is obtained by covering a magnetic detection element such as a Hall IC or MR element with a synthetic resin. Further, the plane 9b of the magnetic detection package 9 is arranged in parallel to the axis L1 of the shaft 3, and the plane 9b of the magnetic detection package 9 is arranged to face the end face 4a (outer peripheral end face) of the magnet 4. The strength of the magnetic field that changes according to the movement of the magnet 4 that strokes with the stroke movement of the shaft 3 is detected. In addition, by making the distance between the magnet 4 and the magnetic detection package 9 as small as possible, a sufficient magnetic flux can be secured, and the influence caused by the output change such as the external magnetic field and the positional deviation of the magnet 4 can be reduced. it can.

  The magnetic detection package 9 is provided on the circuit board 10, and the magnetic detection element incorporated in the magnetic detection package 9 is electrically connected to the circuit board 10 via a lead (not shown), and along with the stroke motion of the shaft 3. The strength of the magnetic field that changes in accordance with the movement of the moving magnet 4 is detected, the detection result is converted into a detection signal, and this detection signal is transmitted through an electric wire 11 electrically connected to the circuit board 10 (analog or analog). Output to the outside (in an output format such as PWM).

  The circuit board 10 is made of a hard circuit board made of a hard insulator such as glass epoxy resin, and is housed and fixed in the second housing portion 13 b of the second case body 13.

  In addition to the magnetic detection package 9, various electronic components such as a capacitor (not shown) are mounted on the circuit board 10.

  The circuit board 10 is provided with a through hole (not shown) for attaching the electric wire 11, and the electric wire 11 and a wiring pattern (not shown) provided on the circuit board 10 are electrically connected by solder (not shown).

  The seal member 12 is made of a synthetic rubber such as nitrile rubber, silicon rubber, or fluororubber, and has an annular shape. The seal member 12 has an annular groove portion 13d that is an outer portion provided on the bottom (end surface) 13c of the second case body 13. When the second unit 8 (second case body 13) is stored and assembled in the first unit 2 (first case body 7), the sealing member 12 is attached to the inside of the bottom portion 7e of the first case body 7. The second case body 13 is fixedly held by a caulking portion 7 f provided between the second case body 13 and the outside of the bottom portion 13 c of the first case body 7. At this time, the seal member 12 is pressed and held by the first case body 7 and the second case body 13. The seal member 12 can ensure airtightness, such as oil or water that has entered the stroke sensor 1 from between the shaft 3 and the first case body 7 (particularly, the first bearing portion 7a). The liquid is prevented from passing through the first case body 7 and the second case body 13 to the side where the electric wire 11 is provided.

  The seal member 12 can be reduced in size by being attached to the bottom portion 13 c of the second case body 13. For example, when it is installed on the cylindrical outer peripheral surface of the second case body 13, it is necessary to provide a groove portion serving as a contact portion for mounting the seal member 12, and the second case body 13 becomes larger in the radial direction. This is because the size is increased.

  Further, when the sealing member 12 is installed on the outer peripheral surface of the second case body 13, when the second case body 13 is formed, it is necessary to employ a slide mold, which increases the cost. When mounted on the bottom 13c of the case body 13, the cost can be reduced because the slide mold is not used.

  Further, when the seal member 12 is installed on the outer peripheral surface of the second case body 13, when the second unit 8 is assembled into the first unit 2, the occurrence of turning of the seal member 12 and the insertion load increase, thereby It is desirable to attach the seal member 12 to the bottom portion 13c because it may cause defects or a reduction in efficiency.

  As shown in FIG. 6, the seal member 12 may be provided with a groove portion 7 h as an arrangement portion inside the bottom portion 7 e of the first case body 7, and may be attached to the groove portion 7 h.

  The second case body 13 is made of a thermoplastic resin material such as polybutylene terephthalate, and the outer shape thereof is a bottomed cylindrical shape, and mainly includes a first storage portion 13a and a second storage portion 13b.

  The first storage portion 13a is located in the second storage portion 13b, and the first storage portion 13a and the second storage portion 13b are partitioned by a partition 13k so as not to communicate with each other. It has a bottomed cylindrical shape. The magnetic detection package 9 and the magnet 4 are provided so as to face each other with the partition 13k interposed therebetween. In addition, the 1st accommodating part 13a, the 2nd accommodating part 13b, and the partition 13k are integrally formed. The openings 13m and 13n of the first storage portion 13a and the openings 13n of the second storage portion 13b are opposite to each other with respect to the center axis of the circular cross section of the second case body 13. . In the present embodiment, the opening 13m of the first storage portion 13a faces the bottom portion 7e side of the first case body 7, and is provided so as to store a part of the shaft 3, the magnet 4 and the holder portion 15. ing.

  The opening 13n of the second storage portion 13b faces the caulking portion 7f side of the first case body 7, and stores and fixes the magnetic detection package 9 and the circuit board 10.

  The inside of the second storage portion 13b is filled with the filler 14. The filler 14 is made of a resin that cures from a liquid such as epoxy or silicone to a solid, and is, for example, a UV curable resin or a thermosetting resin. The magnetic detection package 9 and the circuit board 10 are provided in the second storage portion. 13b is stored and held in an airtight manner.

  Further, when the second storage portion 13b caulks and holds the second unit 8 to the first unit 2 in the assembly process, the bottom portion 13c of the second case body 13 is surely connected to the bottom portion 7e of the first case body 7. A receiving surface 13e against which an assembly tool (caulking machine pressing jig) abuts is provided so as to be pressed.

  In addition, as shown in FIG. 5, the receiving surface 13e is used for suppressing the influence of shape deformation such as deformation due to uneven thickness, or after molding, sinking or warping, or deformation when the filler 14 is thermally cured. For example, it is better that the thickness is equal to the outer peripheral wall 13g of the second case body 13.

  The receiving surface 13e is provided at an end portion of the wall portion 13p that bisects the second storage portion 13b of the second case body 13. The receiving surface 13e provided on the wall 13p reaches the opening 13n of the second storage portion 13b of the second case body 13.

  Filler 14 is filled in the second storage portion 13b in which the circuit board 10 of the divided second storage portion 13b is arranged by the wall portion 13p. By filling the filler 14 only in the space where the circuit board 10 or the like is disposed, the contact area between the filler 14 and the inner wall of the second storage portion 13b can be reduced, It is possible to suppress the stress effect of two materials having different linear expansions, suppress the generation of cracks at the interface between the filler 14 and the inner wall of the second storage portion 13b, and improve the airtightness.

  In addition, in this embodiment, although the 2nd accommodating part 13b is divided into two by the wall part 13p, it is not limited to this embodiment, As it divides the 2nd accommodating part 13b into three or more divisions A wall 13p may be provided. In this case, by providing the wall portion 13p, the area of the receiving surface 13e is increased, the area in contact with the assembly tool is increased, and the contact with the assembly tool is stabilized. Moreover, it becomes possible to increase the intensity | strength of the 2nd case body 13 by providing the wall part 13p in the 2nd accommodating part 13b which is not filled with the filler 14. FIG.

  The second storage portion 13b is provided with a positioning portion 13i that determines the position where the circuit board 10 is disposed, and the circuit board 10 is pressed against the positioning portion 13i by a press-fit portion 13j having a triangular cross-sectional shape. The press-fitting portion 13j has a protruding shape before the circuit board 10 is fixed. However, when the circuit board 10 is attached, the tip portion of the press-fitting portion 13j is crushed so that the circuit board 10 is not detached. .

  The second case body 13 includes a groove portion 13d for mounting the seal member 12 on the outside of the bottom portion 13c.

  With the above configuration, by assembling the two units 2 and 8 in advance and assembling the units 2 and 8, it is possible to improve the assemblability and improve the productivity.

  Further, in the stroke sensor according to the present embodiment, a hard material that can be hardened is used for the shaft 3 in order to suppress wear of the contact portion 3a on the distal end side of the shaft 3 due to repetitive operations that are brought into contact with the detection object. Thus, even when the operation of bringing the shaft 3 into contact with the detection object is repeatedly performed, the wear at the contact portion 3a of the shaft 3 can be remarkably suppressed, and the holder portion 15 made of a non-magnetic material is interposed. Thus, the disturbance of the magnetic field of the magnet 4 received by the magnetism detecting element can be reduced, and a stable stroke amount can be detected.

  Further, by forming the shaft 3 and the magnet 4 with the holder 15 made of a non-magnetic material, the magnetic circuit necessary for the magnetic detection element to perform its function can be maintained, and an accurate stroke amount can be maintained. Can be detected.

  In addition, by plating the surface of the shaft 3, the shaft 3 is plated, so that even if a magnetic material is used, it is rich in rust prevention and can maintain durability.

  FIG. 8 shows another embodiment of the stroke sensor 1 of the present invention. In order to improve the downsizing of the stroke sensor 1 and the external magnetic field resistance, the holder portion 15 includes at least a part of the magnet 4. The magnetic detection element is disposed so as to face the outer peripheral surface 4c of the magnet 4 exposed from the opening 15a. In this embodiment, the holder part 15 is provided so that the magnet 4 which consists of a cylinder shape, and the end surfaces 4a and 4b part of this magnet 4 may be covered. In this case, an opening 15a is provided in the holder portion 15 so that the entire region of the outer peripheral surface 4c of the magnet 4 is exposed.

  Since the outer peripheral surface 4c of the magnet 4 is provided to be exposed from the opening 15a provided in the holder portion 15, the outer peripheral end surface portion of the outer peripheral surface 4c serving as the exposed portion of the magnet 4 and the package of the magnetic detection element 9 The distance from the end face portion can be reduced, downsizing can be realized, the magnetic flux density from the magnet 4 received by the magnetic detection element (magnetic detection package 9) is increased, and the external magnetic field resistance is improved. be able to.

  The present invention can be used for a stroke sensor that detects the amount of movement of a magnet provided on a shaft that moves as the object to be detected moves.

DESCRIPTION OF SYMBOLS 1 Stroke sensor 2 1st unit 3 Shaft 3a Contact part 3b Rear end part 3c Large diameter part (stopper part)
3d Small diameter part 3e Medium diameter part 4 Magnet 4a, 4b End face 4c Outer peripheral surface 5 Elastic member (coil spring)
6 second bearing portion 6a large diameter portion 6b small diameter portion 6c inner diameter portion 6d spring receiving portion 7 first case body 7a first bearing portion 7b abutting portion 7c first storage portion 7d second storage portion 7e bottom portion 7f caulking portion 7g Mounting portion 7h Groove portion 8 Second unit 9 Magnetic detection package 9b Plane 10 Circuit board 11 Electric wire 12 Seal member 13 Second case body 13a First housing portion 13b Second housing portion 13c Bottom portion 13d Arrangement portion (groove portion)
13e receiving surface 13g outer peripheral wall 13i positioning part 13j press-fitting part 13k partition 13m opening 13n opening 13p wall part 14 filler 15 holder part 15a opening part L1 axis

Claims (3)

  In a stroke sensor that detects the amount of movement of a magnet provided on a shaft that moves along with the movement of the detected object, the shaft is made of a magnetic material, and the contact portion with the detected object is at least quenched, and the shaft A holder portion made of a non-magnetic material provided integrally with the shaft, located on the side opposite to the contact portion portion of the shaft, the magnet disposed in the holder portion, and along the longitudinal direction of the shaft A first unit including at least an elastic member that elastically biases the shaft toward the body to be detected; a first case body that supports and arranges the shaft and the elastic member; and a magnetic field of the magnet. A magnetic detection element for detection; a circuit board on which the magnetic detection element is mounted; and a second case body for supporting the magnetic detection element and the circuit board. And a two unit, said first, second case body is formed in a tubular shape, a stroke sensor, wherein the second unit is incorporated into the first unit.   The stroke sensor according to claim 1, wherein a surface of the shaft is plated. The holder part has an opening part that exposes at least a part of the magnet, and the magnetic detection element is arranged to face the magnet part exposed from the opening part. The stroke sensor according to claim 1 or 2.

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