JP6653062B2 - Stroke sensor - Google Patents

Description

  The present invention relates to a stroke sensor.

  2. Description of the Related Art As a stroke sensor for detecting a moving amount of a moving body such as a lever of a car or a motorcycle, there is a stroke sensor disclosed in, for example, Patent Document 1. The stroke sensor includes a shaft that follows the movement of the object to be detected, a housing in which the shaft is housed, a cap portion that is arranged to close one end of the housing and supports sliding of a shaft that penetrates, and a cap portion of the shaft. A magnet provided at the other end, a magnetic detection element provided in the housing to detect a change in the magnetic field of the magnet, and an origin return mechanism for returning the shaft to the origin position after the shaft reciprocates; Detects the amount of reciprocation in the axial direction by the change in the magnetic field.

DE 10 201 100 15036 A1

  However, in the stroke sensor described in Patent Document 1, the sliding portion supporting the shaft is formed by the inner peripheral surface of the cap portion closing one end of the housing. In addition, because the magnet is located at the tip of the shaft, if the center of the magnet and the center of the shaft deviate from each other, the detection gap between the magnet and the magnetic detection element fluctuates with the movement of the shaft, resulting in lower detection accuracy. There is a problem of lowering.

  In addition, if the center of the magnet and the center of the shaft deviate from each other, there is a problem that the shaft is strongly applied to a part of the sliding portion and local wear is likely to occur.

  In addition, when the number of sliding portions serving as bearings for each component is increased, the shaft becomes a resisting force when moving, so that a desired operational feeling (a constant operational feeling) may not be provided. Met.

  An object of the present invention is to provide a stroke sensor that can improve detection accuracy and give a desired operation feeling, focusing on the above problem.

In order to achieve the above object, a stroke sensor according to the present invention includes:
A stroke sensor that has a magnet and detects the amount of movement of a detection shaft that reciprocates around an origin position following a detected object by a magnetic detection element,
A housing that regulates the rotation of the detection shaft and slidably supports the rotation;
An origin return mechanism provided between the detection shaft and the housing to detect the movement amount and return the detection shaft after the movement to the origin position.
The origin return mechanism is provided with a pair of pistons, a spring sandwiched between the pair of pistons,
The pair of pistons may be provided with a gap between the pair of pistons and an inner wall surface of the housing .

A magnet provided on a side surface of the detection shaft;
And a magnetic detection element provided in the housing so as to face the magnet and detecting the amount of movement from a change in a magnetic field accompanying movement of the detection shaft.

The detection shaft includes a first shaft made of a non-magnetic material and a second shaft made of a magnetic material connected to the first shaft.
A first housing supporting the first shaft is made of a non-magnetic material;
It is characterized by the following.

Further, the second shaft, a second housing that houses the second shaft, and the origin return mechanism that is housed in the second housing are made of a metal material.
It is characterized by the following.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes a stroke sensor which can improve detection accuracy and can give a desired operation feeling.

FIG. 3A is a plan view, FIG. 3B is a cross-sectional view taken along line AA, FIG. 3C is a cross-sectional view taken along line BB, and FIG. It is sectional drawing of the 1st shaft of one Embodiment of this invention. It is sectional drawing of the 2nd shaft of one Embodiment of this invention. It is sectional drawing of the 1st housing of one Embodiment of this invention. It is sectional drawing of the 2nd housing of one Embodiment of this invention. It is a sectional view of an origin return mechanism of one embodiment of the present invention.

  Hereinafter, a stroke sensor according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the stroke sensor 1 of the present invention is a stroke sensor that detects the amount of movement of a detection shaft 10 that reciprocates around an origin position O following an object to be detected. A housing 20 that regulates rotation and slidably supports, and an origin return mechanism that is provided between the detection shaft 10 and the housing 20 and that detects the amount of movement and returns the detection shaft 10 that has moved to the origin position O. A magnet 40 provided on the side surface of the detection shaft 10, and a magnetism detection element 50 provided on the housing 20 to face the magnet 40 and detecting a movement amount from a change in a magnetic field accompanying the movement of the detection shaft 10. It is configured to have.

  The detection shaft 10 according to the present embodiment is a detection medium that follows the movement of the detected object, and for example, is connected to the detected object, receives an external force, and reciprocates in the axial direction to follow. As shown in FIGS. 1 to 3, the detection shaft 10 includes a first shaft 11 and a second shaft 12, and the first shaft 11 and the second shaft 12 are connected by screws.

  The first shaft 11 is made of a non-magnetic metal having a certain degree of rigidity, and is typically made of austenitic stainless steel (SUS: Steel Use Stainless). The first shaft 11 includes three large-diameter portions 11a having different diameters, a middle-diameter portion 11b, and a small-diameter portion 11c.

  The small-diameter portion 11c protrudes outward from the housing 20 (the first housing 21), and is formed with, for example, a male screw 11d to be connected to the detection target, and is connected to and follows the detection target by a screw.

The large-diameter portion 11a and the middle-diameter portion 11b are disposed inside the housing 20 (first housing 21), and rotation thereof is regulated by a sliding support portion 23 described later between the housing 20 (first housing 21). It is supported so that it can slide.

  The large-diameter portion 11a has a female screw portion 11e for connecting to the second shaft 12 on the end face opposite to the small-diameter portion 11c. Further, a centering groove 11f for securing the position of the second shaft 12 and the centering state with the first shaft 11 is formed concentrically on the outer peripheral portion of the female screw portion 11e on the end face of the large diameter portion 11a. is there. By forming this centering groove 11f, the center of the second shaft 12 and the center of the first shaft 11 are matched with high accuracy on the inner peripheral surface of the centering groove 11f, and the annular flat end surface of the second shaft 12 is formed. The fastening position can be held at a predetermined value and the connection can be made. Thereby, eccentricity with respect to the first shaft 11 due to the load of the spring 31c applied to the second shaft 12 described later can be suppressed as much as possible.

  An end surface of the end surface of the large-diameter portion 11a outside the centering groove 11f is a locking portion 11g of the piston 31a of the home position return mechanism 30 described later, and when the first shaft 11 is pushed, a pushing force is applied to the piston 31a. introduce. Accordingly, a drag is generated by the spring 31c via the piston 31a, and the first shaft 11 can be returned to the origin position O.

  The large-diameter portion 11a has a cutout surface 11h having a flat side surface formed at an end opposite to the small-diameter portion 11c, and has a substantially D-shaped cross-sectional shape. The length of the cutout surface 11h in the axial direction of the first shaft 11 is the same as or slightly longer than the detection stroke S. The rotation of the first shaft 11 is regulated by the cutout surface 11h in cooperation with a sliding support portion 23 of the housing 20 (first housing 21) described later.

  The radially intermediate portion 11b has a magnet storage portion 11i in the radial direction formed on a side surface. The magnet housing portion 11i houses the magnet 40 and is fixed with an adhesive or the like.

  The second shaft 12 is connected to the first shaft 11 to form the detection shaft 10, and is housed in the housing 20 (second housing 22). The second shaft 12 is made of, for example, a metal material. As with the first shaft 11, the second shaft 12 is preferably made of a non-magnetic material. However, since the second shaft 12 has a sufficient distance from the magnet 40, the influence on the magnetic field of a soft magnetic material such as steel is small. The material is low, and the material can be appropriately selected in consideration of cost and strength.

  The second shaft 12 includes three large-diameter portions 12a having different diameters, a middle-diameter portion 12b, and a small-diameter portion 12c. A male screw 12d is formed in the small diameter portion 12c, and a step 12e is formed between the male screw 12d and the middle diameter portion 12b. Thus, the second shaft 12 and the first shaft 11 are connected by the male screw portion 12d and the female screw portion 11e of the first shaft 11, and the step 12e is tightened so as to fit into the centering groove 11f of the first shaft 11. Thus, they are connected in a centered state and at a predetermined axial position. Upon connection, the screws are prevented from being loosened with a reinforcing adhesive (for example, a sealock agent) or the like.

  The middle diameter portion 12b is formed in a columnar shape having a predetermined axial length, and is provided with pistons 31a and 31b and a spring 31c of an origin return mechanism 30, which will be described later.

  The large-diameter portion 12a forms a locking portion 12f of the piston 31b of the home return mechanism 30 described later, and forms a pair with a locking portion 11g of the piston 31a of the first shaft 11. The outer periphery of the large-diameter portion 12 a is, for example, a hexagonal shape, and can be turned with a tool such as a wrench when connecting to the first shaft 11.

  As shown in FIGS. 1, 4 and 5, the housing 20 includes a first housing 21 in which the first shaft 11 is mainly housed, and a first housing 21 connected to the first housing 21 and in which the second shaft 12 is mainly housed. And two housings 22.

  The first housing 21 is made of a nonmagnetic material and is formed in a substantially cylindrical shape. For example, a metal material such as aluminum or stainless steel, or a synthetic resin material such as PBT (Poly Butylene Terephthalate) or PPS (Poly Phenylene Sulfide) is used. Used. A large-diameter hole portion 21a, a medium-diameter hole portion 21b, and a small-diameter hole portion 21c are formed continuously in the inner peripheral portion of the first housing 21, and the medium-diameter hole portion 21b and the small-diameter hole portion 21c are formed. The sliding support portion 23 of the first shaft 11 is configured.

  The large-diameter hole portion 21a has a female screw portion 21d formed at an intermediate portion of the inner peripheral surface, and the second housing 22 is connected with a screw. In the large-diameter hole 21a, a peripheral surface 21e and an end surface 21f formed on the distal end side (the intermediate-diameter hole 21b side) of the female screw portion 21d are fitted with the second housing 22, and the centering and the axial connection position are performed. Set. The end surface 21f of the large-diameter hole portion 21a serves as a contact surface of a piston 31a of the home position return mechanism 30 described later.

  As shown in FIG. 1 and FIG. 4, the intermediate hole 21 b is formed in a substantially D-shaped cross section that comes into contact with the outer surface of the cutout surface 11 h of the large diameter portion 11 a of the first shaft 11. Is formed to have a sufficient axial length even if the first shaft 11 moves by the detection stroke S of the first shaft 11.

  The small-diameter hole portion 21c is formed at an inner diameter in which the middle diameter portion 12b of the first shaft 11 can slide. Thus, the rotation of the first shaft 11 around the central axis is restricted by the substantially D-shape and the small-diameter hole portion 21c of the medium-diameter hole portion 21b constituting the sliding support portion 23 of the housing 20, and in the axial direction. , And is supported so that sliding for the detection stroke S is performed with high accuracy. Accordingly, the rotation of the first shaft 11 is regulated by the first housing 21 for substantially the entire length, and the first shaft 11 is slidably supported.

  The first housing 21 is formed with a board storage portion 21g of the circuit board 51 on which the magnetic detection element 50 is mounted, facing the magnet storage portion 11i of the first shaft 11. A rectangular recess having a bottom surface parallel to the notch surface 11h of the first shaft 11 is formed in the substrate storage portion 21g, and protrudes upward from the bottom surface to temporarily fix the positioning pins 21h of the circuit substrate 51 and the circuit substrate 51. A female screw portion 21i for a screw is formed. By providing the female pins 21i for the screws for temporarily fixing the positioning pins 21h and the circuit board 51 in the board storage section 21g, the magnetic sensing element 50 mounted on the circuit board 51 can be placed in the first space with a gap as small as possible with respect to the magnet 40. It can be fixed to the housing 21 and can accurately detect a change in the magnetic field due to the magnet 40.

  The second housing 22 is connected to the first housing 21 to form the housing 20, and for example, a metal material is used. As with the first housing 21, the second housing 22 is preferably made of a non-magnetic material. However, since the second housing 22 has a sufficient distance from the magnet 40, the degree of influence on the magnetic field can be reduced even with a soft magnetic material such as steel. The material is low, and the material can be appropriately selected in consideration of cost and strength.

  As shown in FIGS. 1 and 5, the second housing 22 is formed in a cylindrical shape having an outer shape of substantially two steps, and includes a large-diameter portion 22a and a small-diameter portion 22b.

  A male screw 22c is formed on the outer periphery of the middle portion of the large-diameter portion 22a, and an outer peripheral portion 22d and a distal end surface 22e on the tip side from the male screw 22c are fitted to the peripheral surface 21e and the end surface 21f of the first housing 21. There is. Thus, the male screw 22c of the second housing 22 and the female screw portion 21d of the first housing 21 can be connected to each other in a centered state and at a predetermined position in the axial direction.

  On the inner peripheral side of the large-diameter portion 22a, a cylindrical large-diameter hole portion 22f and a small-diameter hole portion 22g are continuously formed, and the large-diameter hole portion 22f connects the pistons 31a, 31b and the spring 31c of the origin return mechanism 30. It becomes the piston storage part 31d to store. The small-diameter hole portion 22g is a storage space for the large-diameter portion 12a at the end of the second shaft 12. In addition, a step surface 22h between the large-diameter hole portion 22f and the small-diameter hole portion 22g serves as a contact surface of a piston 31b of the origin return mechanism 30 described later.

The small-diameter portion 22b has a female screw portion 22i formed at the center from the outer end surface, and is used to hold the small-diameter portion 22b on a detection target that is a stroke detection target.
The second housing 22 is not limited to the case where the second housing 22 is formed of a metal material, and may be formed by insert-molding a screw portion as a metal material in a synthetic resin material.

  As shown in FIGS. 1 and 6, the origin return mechanism 30 includes a pair of pistons 31a and 31b, and a spring 31c mounted between the two pistons 31a and 31b and biasing the pistons 31a and 31b to separate each other. Be composed.

  For example, a metal material is used for the two pistons 31a and 31b. The two pistons 31a and 31b are preferably made of a non-magnetic material, but since the distance from the magnet 40 is ensured, even a soft magnetic material such as a steel material has a low degree of influence on the magnetic field, and has high durability and durability. The material can be appropriately selected in consideration of the strength.

  The two pistons 31a and 31b are formed in a cylindrical shape with a bottom, and a mounting hole for mounting to the middle diameter portion 12b of the second shaft 12 is formed at the center of the bottom portion. The two pistons 31a and 31b are opposed to each other with the bottom part facing outward, slidably mounted on the middle diameter portion 12b of the second shaft 12, and a spring 31c formed of a coil spring is interposed between the two pistons 31a and 31b. And mounted on the second shaft 12.

  The two pistons 31a and 31b are arranged in a large-diameter hole portion 22f (piston storage portion 31d) of the second housing 22 formed by connecting the first housing 21 and the second housing 22. The two pistons 31a and 31b have a gap D1 with the inner wall surface of the large-diameter hole portion 22f (piston storage portion 31d), and when the first shaft 11 and the second shaft 12 move by reducing the mutual contact area. Resistance has been reduced. In addition, the gap D1 facilitates the work when assembling the second shaft 12 on which the two pistons 31a and 31b and the spring 31c are mounted to the large-diameter hole 22f. Further, in addition to the mutual diameter setting for the second shaft 12 and the two pistons 31a and 31b to slide, the clearance D1 is provided so that a large load is applied at the time of assembling work or after mounting on the vehicle. Eccentric, it is difficult for the two pistons 31a and 31b to come into contact with the inner wall surface of the large-diameter hole portion 22f (piston storage portion 31d), so that the spring 31c, the two pistons 31a and 31b, and the inner wall surface Factors that affect the operational feeling, such as being damaged, can be prevented.

  The spring 31c is formed of a coil spring made of stainless steel, for example, SUS304WPB. The spring 31c is preferably made of a non-magnetic metal such as stainless steel (for example, SUS304WPB). However, since the spring 31c has a distance from the magnet 40, even if it is made of a soft magnetic material (for example, SWB or SWC), the spring 31c may have a magnetic field. Since the degree of influence is small, a material may be appropriately selected in consideration of durability and strength. Also, regardless of the position of the shaft 10, the two pistons 31a and 31b can be pressed against the end surface 21f and the step surface 22h by the spring 31c. Even the pistons 31a and 31b can be held without vibrating. For this reason, a certain operational feeling can be provided for the stroke of the shaft 10. Further, by preventing the vibration of the two pistons 31a and 31b, the detection accuracy of the magnetic detection element 50 can be stabilized.

  At the origin position O, the two pistons 31a and 31b of the home position return mechanism 30 have the outer surface of the piston 31a (the outer surface of the bottom of the bottomed cylinder) of the large-diameter hole portion 21a of the first housing 21 as shown in FIG. And the outer surface of the other piston 31b (the outer surface of the bottom of the bottomed cylinder) abuts on the step surface 22h of the large-diameter hole portion 22f of the second housing 22, whereby the separation distance is regulated. You. The separation distance (interval) between the cylindrical portions of the two pistons 31a and 31b in this state (origin position O) is the detection stroke S of the detection shaft 10 (see FIG. 6).

  Further, at the origin position O, the outer surface of the piston 31a (the outer surface of the bottom of the bottomed cylinder) comes into contact with the locking portion 11g which is the end surface of the large-diameter portion 11a of the first shaft 11, and the other piston 31b (The outer surface of the bottom of the bottomed cylinder) is in contact with the end surface of the large diameter portion 12a of the second shaft 12 on the first shaft 11 side.

  In the home position return mechanism 30, when the detection shaft 10 at the home position O is displaced so as to be pushed into the housing 20, the detection shaft 10 is moved out of the piston 31a via the locking portion 11g which is the end surface of the large-diameter portion 11a of the first shaft 11. The side surface (the outer surface of the bottom of the bottomed cylinder) is pushed in, and the other piston 31b cannot contact the stepped surface 22h of the large-diameter hole portion 22f of the second housing 22 and cannot move. It can move by the detection stroke S until the cylindrical portions of the pistons 31a and 31b hit. Then, when the force for pushing the detection shaft 10 is lost, the detection shaft 10 is returned to the origin position O by the spring force accumulated in the spring 31c.

  In the home position return mechanism 30, when the detection shaft 10 at the home position O is displaced so as to be pulled out of the housing 20, the outer surface of the piston 31 b (the outer surface of the bottom of the bottomed cylinder) has the diameter of the second shaft 12. The large portion 12a is pulled out through the end surface on the first shaft 11 side, and the outer surface of the piston 31a (the outer surface of the bottom of the bottomed cylinder) contacts the end surface 21f of the large-diameter hole 21a of the first housing 21 and moves. It cannot move, and can move by the detection stroke S until the cylindrical portions of the two pistons 31a and 31b hit against the spring 31c. When there is no longer any force to pull out the detection shaft 10, the detection shaft 10 is returned to the origin position O by the spring force accumulated in the spring 31c. In addition, a lubricant such as grease is applied to the outer peripheral surface of the piston storage portion 31d in which the pistons 31a and 31b are stored, thereby ensuring long-term stable sliding with respect to the second shaft 12.

  The magnet 40 is formed of a rare-earth-based magnet (for example, a magnet made of a material such as SmCo or NdFeB) formed in a square pillar shape or a cylindrical shape. In this embodiment, the magnet 40 has a cylindrical shape using a sintered SmCo magnet, and has two poles magnetized in a vertical direction (magnet thickness direction) which is a long axis direction. The magnet 40 is housed in the magnet housing portion 11i of the first shaft 11 of the detection shaft 10, and is fixed with an adhesive or the like.

  The magnet 40 provides a magnetic field to the magnetic detection element 50 facing the magnet 40 of the first housing 21, and the direction (magnetic force) of the magnetic field applied to the magnetic detection element 50 when the magnet 40 is displaced together with the detection shaft 10. Is changed, and as a result, the magnetic detection element 50 detects the movement amount. The magnet 40 may be any of a sintered magnet and a plastic magnet that is compressed or molded by being mixed with a plastic according to a manufacturing method. Sintered magnets have a stronger magnetic force, while plastic magnets have characteristics such as higher mass productivity and higher crack resistance. Therefore, they may be appropriately selected according to use conditions and design requirements.

  The magnetic detection element 50 detects displacement such as the amount of movement of the object to be detected, and is constituted by, for example, a Hall element or the like, and converts a change in magnetic force accompanying the displacement such as movement of the object to be detected into an electric signal. Output to the outside. For example, the magnetic detection element 50 is configured as a magnetic detection package by mounting a plurality of Hall elements on a circuit board 51.

Here, the detection surface of the magnetic detection element 50 of the magnetic detection package is arranged in a direction perpendicular to the magnetization direction of the magnet 40. In the magnetic detection package including the magnetic detection element 50, the circuit board 51 is housed in the board housing portion 21g of the housing 20 (the first housing 21), and is temporarily fixed to the positioning pins 21h and the female screw portions 21i with screws. It is kept airtight by the seal member and the lid. By doing so, the gap with the magnet 40 is made as small as possible so that a change in the magnetic field can be detected with high accuracy.

  The power supply to the magnetic detection element 50 of the magnetic detection package and the output to the outside are performed by a direct connector or a cord. The magnetic detection element 50 may be mounted on a wire frame or the like and configured as a magnetic detection package.

  The detection of the stroke S in the magnetic detection package 9 using the magnetic detection element 50 is performed by using a plurality of Hall elements of the circuit board 51 and detecting the magnetic field formed by the magnet 40 in the direction perpendicular to the magnetic detection surface of the magnetic detection element 50. The magnetic field in the direction is detected. The obtained magnetic fields in the two directions of the vertical direction and the horizontal direction are angle-converted by a processing circuit (for example, an ASIC; Application Specific Integrated Circuit) by a trigonometric function (ATAN) and output as angle information. Note that the output angle information is proportional to the movement amount (stroke S) of the detection shaft 10, and as a result, the movement amount of the detection shaft 10 can be detected.

  The output method from the magnetic detection package including the magnetic detection element 50 may be any method, and may be selected according to a control unit (ECU: Engine Control Unit) using the detection result ( For example, analog, PWM (Pulse Width Modulation), SENT (Single Edge Nibble Transmission).

  According to such a stroke sensor 1, since the detection shaft 10 is slidably supported by restricting the rotation by the sliding support portion 23 of the housing 20, the support width with respect to the entire length of the detection shaft 10 is increased. The contact area can be increased and supported, and the detection shaft 10 can be slid with respect to the housing 20 in a stable state.

  Thereby, the gap between the magnet 40 attached to the detection shaft 10 whose rotation is restricted and the magnetic detection element 50 attached to the housing 20 can be made as small as possible, and a change in the magnetic field can be detected with high accuracy. Further, by attaching the magnet 40 to the side surface of the detection shaft 10, a small magnet 40 can be obtained, and the stroke can be detected from a large change by concentrating the magnetic field.

  In addition, since the detection shaft 10 slides with respect to the housing 20 without rotating, there is no swing of the detection shaft 10 having a large contact area, and a part of the detection shaft 10 can be prevented from strongly hitting the housing 20. The durability can be improved by preventing the occurrence of local wear.

  In addition, the magnet 40 and the magnetic detection element 50 serving as a magnetic detection unit are concentrated on one side of the detection shaft 10 and the housing 20, and the origin return mechanism 30 is arranged on the other side. By making one side a non-magnetic material, even if the other side is made of a magnetic metal material, it is possible to detect a change in the magnetic field by minimizing the influence on the magnetic field. Thereby, durability can be improved by using the metal material for the origin return mechanism 30.

  In addition, by dividing the iron-based material into non-magnetic and magnetic on one side and the other side of the detection shaft 10 and the housing 20, it is possible to suppress the influence of a magnetic field change by using the periphery of the magnet 40 as a non-magnetic material. Thus, the detection accuracy can be improved, and the other side can increase the degree of freedom of material selection.

  According to such a stroke sensor 1, the stroke sensor 1 having the magnet 40 and detecting the moving amount of the detection shaft 10 reciprocating around the origin position O following the detected object by the magnetic detection element 50. A housing 20 that regulates the rotation of the detection shaft 10 and slidably supports the detection shaft 10; and moves the detection shaft 10 provided between the detection shaft 10 and the housing 20 to detect the movement amount and moved to the origin position O. An origin return mechanism 30 for returning, the origin return mechanism 30 is provided with a pair of pistons 31a, 31b and a spring 31c sandwiched between the pair of pistons 31a, 31b, and the pair of pistons 31a, 31b A gap D1 is provided between the inner wall surface of the housing 20 and the opposing inner wall surface.

  Therefore, the resistance when the detection shaft 10 moves can be reduced, and a desired operation feeling (a constant operation feeling) can be provided. Further, the vibration of the pistons 31a and 31b can be suppressed by the spring 31c, and the detection accuracy of the magnetic detection element 50 can be improved.

Further, it has a magnet 40 provided on the side surface of the detection shaft 10, and a magnetism detection element 50 provided on the housing 20 so as to face the magnet 40 and detects a movement amount from a change in a magnetic field accompanying the movement of the detection shaft 10. Therefore, the detection accuracy can be improved by the magnet 40 and the magnetic detection element 50 having a small gap, and the detection shaft, which is restricted in rotation and slides, is supported by the housing 20 with an increased contact area, so that the Wear can be reduced. Further, the gap between the magnetism detecting element 50 attached to the housing 20 and the magnet 40 of the detection shaft 10 can be reduced, the gap fluctuation can be suppressed, the disturbance of the magnetic field can be reduced, and the change in the magnetic field can be detected with high accuracy.

  According to the stroke sensor 1, the detection shaft 10 includes the first shaft 11 made of a non-magnetic material and the second shaft 12 made of a magnetic material connected to the first shaft 11. Since the first housing 21 to be supported is made of a non-magnetic material, the materials used can be divided between the first shaft 11 and the first housing 21 and the second shaft 12 and the second housing 22. By dividing the iron-based material into non-magnetic and magnetic, the influence of a magnetic field change can be suppressed by using the peripheral portion of the magnet 40 as a non-magnetic material, and the detection accuracy can be improved.

  Further, according to the stroke sensor 1, the second shaft 12, the second housing 22 that houses the second shaft 12, and the origin return mechanism 30 that is housed in the second housing are made of a metal material, so that the The material used can be made into consideration of the durability and strength while suppressing the influence on the detection unit, and the durability and strength can be more reliably improved.

  In the above-described embodiment, the detection shaft 10 is configured by connecting the first shaft 11 and the second shaft 12, but is configured by one shaft, and only the large-diameter portion 12a of the second shaft 12 is used. You may make it attach with a screw etc. In this case, it is preferable to provide a positioning groove so that positioning in the axial direction can be performed.

  Further, in the above-described embodiment, the configuration in which the magnet is provided on the side surface of the detection shaft has been described. However, when the position detection accuracy of the magnet is sufficiently obtained by the magnetic detection element, the magnet is provided on the axis side of the detection shaft. It can also be configured as follows.

Reference Signs List 1 Stroke sensor 10 Detection shaft 11 First shaft 11a Large diameter portion 11b Medium diameter portion 11c Small diameter portion 11d Male screw portion 11e Female screw portion 11f Centering groove 11g Locking portion 11h Notch surface 11i Magnet storage portion 12 Second shaft 12a Large diameter Part 12b Middle diameter part 12c Small diameter part 12d Male screw 12e Stepped part 12f Locking part 20 Housing 21 First housing 21a Large diameter hole 21b Medium diameter hole 21c Small diameter hole 21d Female screw part 21e Peripheral surface 21f End face 21g Board storage part 21h Positioning Pin 21i Female thread portion 22 Second housing 22a Large diameter portion 22b Small diameter portion 22c Male screw 22d Outer peripheral surface 22e Tip surface 22f Large diameter hole portion 22g Small diameter hole portion 22h Step surface 22i Female screw portion 23 Sliding support portion 30 Origin return mechanism 31a Piston 31b Piston 31c Spring 31d Piston storage 40 Magnet 50 Magnetic detection element 51 Circuit board O Origin position S Detection stroke

Claims (4)

A stroke sensor that has a magnet and detects the amount of movement of a detection shaft that reciprocates around an origin position following a detected object by a magnetic detection element,
A housing that slidably supports the rotation of the detection shaft by regulating the rotation of the detection shaft;
An origin return mechanism provided between the detection shaft and the housing to detect the movement amount and return the detection shaft after the movement to the origin position.
The origin return mechanism is provided with a pair of pistons, a spring sandwiched between the pair of pistons,
A stroke sensor, wherein a gap is provided between the pair of pistons and an inner wall surface of the housing facing the piston. A magnet provided on a side surface of the detection shaft;
The magnetism detection element , which is provided in the housing to face the magnet and detects the amount of movement from a change in a magnetic field accompanying the movement of the detection shaft,
The stroke sensor according to claim 1, wherein: The detection shaft includes a first shaft made of a non-magnetic material, and a second shaft made of a magnetic material connected to the first shaft.
A first housing supporting the first shaft is made of a non-magnetic material;
The stroke sensor according to claim 1, wherein: The second shaft, a second housing that houses the second shaft, and the origin return mechanism that is housed in the second housing are made of a metal material.
The stroke sensor according to claim 3, wherein:

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