JP5344374B2 - Rotation angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detector capable of preventing generation of abrasion powder by a washer. <P>SOLUTION: The rotation angle detector A includes: a magnet 3 provided on a rotating shaft 2; a magnetic detection element 4 for detecting a change in magnetic force due to the rotation of the magnet 3; and a housing 1 provided with a first storage part 1i wherein the shaft 2 is disposed rotatably. In the device A, a resin washer 11 is provided in the opening 1p of the first storage part 1i so as to prevent the shaft 2 from coming off from the first storage part 1i, and the washer 11 has a linear expansion coefficient equal to or substantially equal to that of the housing 1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a detection object, and is suitable for a throttle position sensor and a steering angle sensor of an automobile, for example.

  As a conventional rotation angle detection device, one disclosed in Patent Document 1 is known. In this rotation angle detection device, a magnet provided on a shaft member that rotates in response to the rotation of a rotating body, a magnetic force change due to rotation of the magnet, a magnetic detection element, and a first shaft that rotatably arranges the shaft member. And a housing integrally provided so as not to communicate with each other, and a second storage portion in which the magnetic detection element is disposed via a circuit board.

JP 2008-185490 A

  However, in the rotation angle detection device described in Patent Document 1, a metal washer is press-fitted into the opening of the first storage portion so that the shaft member does not come out of the first storage portion, and then the first Since the washer is fixed by caulking the opening of the first storage portion, the heat sink and the washer are made of metal when subjected to heat or vibration. Therefore, the contact position of the first storage portion and the shaft member There is a possibility that the wear powder generated by the wear enters the sliding surfaces of the shaft member and the first storage portion, the slidability is deteriorated, and the detection accuracy is adversely affected.

  Accordingly, the present invention focuses on the above-described problems and provides a rotation angle detection device capable of preventing the generation of wear powder due to a washer.

  The present invention includes a magnet provided on a rotating shaft member, a magnetic detection element for a change in magnetic force due to the rotation of the magnet, and a housing provided with a first housing portion that rotatably arranges the shaft member. In the rotation angle detection apparatus, a resin washer is provided in the opening of the first housing portion so that the shaft member does not come out of the first housing portion, and the washer has the same or substantially the same linear expansion coefficient as the housing. It is what has.

  In the present invention, a protrusion for press-fitting the washer is provided in the opening.

  ADVANTAGE OF THE INVENTION According to this invention, the rotation angle detection apparatus which can achieve the objective and can prevent generation | occurrence | production of the abrasion powder by a washer can be provided.

Sectional drawing of the rotation angle detection apparatus by embodiment of this invention. Sectional drawing which decomposed | disassembled each component of the rotation angle detection apparatus by the embodiment. The top view of the rotation angle detection apparatus by the embodiment. Sectional drawing of the XX line in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 to 4 show an embodiment of the present invention, in which the present invention is applied to a rotation angle detection device for detecting the rotation angle of a steering mounted on a vehicle.

  The rotation angle detection device A according to the present embodiment is mainly composed of a housing 1, a shaft member 2, a magnet 3, a magnetic detection element 4, and a circuit board 5.

  The housing 1 is made of a thermoplastic resin material such as polybutylene terephthalate, and includes a base portion 1a formed in a substantially cylindrical shape. The base portion 1a forms a hollow portion 1i that is a first storage portion in which the shaft member 2 is rotatably disposed.

  An upper end 1b of the base 1a that forms the cavity 1i is formed with an opening 1p for disposing a washer, which will be described later, and a caulking portion 1c for caulking and fixing the washer. The caulking portion 1c presses the entire circumference of the washer.

  The opening 1p is provided with a protrusion 1q for press-fitting the washer. Three protrusions 1q are provided inside the opening 1p. The protrusion 1q is in contact with the outer periphery of the washer.

  1k is a receiving part that supports an outer edge part of a washer, which will be described later. This receiving part 1k is provided in the opening 1q at the upper end part 1b, and when the shaft member 2 is housed in the housing 1, the receiving part 1k It is located on substantially the same plane as a first mounting surface to be described later. The receiving portion 1k provided with the protrusion 1q is provided with a recess 1r. The recess 1r is provided only around the protrusion 1q, and accommodates the protrusion 1q that is crushed and deformed by the washer when the washer is press-fitted into the protrusion 1q.

  An annular wall portion 1e surrounding the circuit board 5 is extended and formed at the lower end portion 1d of the base portion 1a on the side opposite to the portion where the caulking portion 1c is formed. That is, the magnetic detection element 4 and the circuit board 5 are disposed in the space 1m that is the second storage portion by the annular wall portion 1e.

  The hollow portion 1 i that is the first storage portion and the space portion 1 m that is the second storage portion are provided integrally with the housing 1.

  Reference numeral 1f denotes a storage portion having a substantially bag shape (substantially concave shape in cross section) for storing the magnetic detection element 4 mounted on the circuit board 5, and protrudes into the hollow portion 1i that is the first storage portion. It is provided in the formed protrusion 1n. The projecting portion 1n is configured to be connected to the lower end portion 1d of the base portion 1a through a connecting portion 1h having an opening end portion 1g formed in a substantially annular plate shape. In other words, it can be said that the accommodating portion 1f is accommodated in a second recess, which will be described later, of the shaft member 2 disposed in the hollow portion 1i serving as the internal space of the base portion 1a. Further, the protruding portion 1n and the connecting portion 1h separate the hollow portion 1i that is the first storage portion and the space portion 1m that is the second storage portion so as not to communicate with each other.

  Reference numeral 1j denotes an annular groove formed by cutting out and fixing the outer peripheral portion of the ring-shaped magnetic member 6. The annular groove 1j is an inner wall surface of the cavity 1i serving as an internal space of the base 1a. It is obtained by cutting out.

  In the case of this embodiment, the housing 1 and the magnetic member 6 are integrally formed by insert molding. Alternatively, the housing 1 and the magnetic member 6 may be integrally formed by press-fitting and fixing the magnetic member 6 in the annular groove 1j of the housing 1. When the housing 1 and the magnetic member 6 are integrally formed as described above, the inner peripheral upper end surface of the magnetic member 6 comes into contact with a flat surface (described later) of the shaft member 2 when the shaft member 2 is housed in the housing 1. Therefore, it has a function as a support portion for supporting the flat surface.

  The shaft member 2 is made of a synthetic resin material such as polyacetal, and as shown in FIG. 1, the shaft member 2 is formed in a substantially “H” cross section and has a substantially cylindrical shape, and an internal space region of the cylindrical portion 2a. And a disc portion 2b arranged to divide the upper and lower sides. That is, the cylindrical portion 2a includes a first concave portion 2c formed above the cylindrical portion 2a having a substantially cylindrical cup shape by interposing the disc portion 2b at a substantially central portion of the inner space region thereof. And a second recess 2d formed below the cylindrical portion 2a.

  A tip portion 2e of the first concave portion 2c having a substantially cylindrical cup shape (in other words, a tip portion 2e of the first concave portion 2c protruding upward in FIG. 1 of the washer) is a detection target (rotating body). It is connected to the steering directly or via a member such as a gear. Thereby, the front-end | tip part 2e has a function as a rotation input part (rotation transmission part) for rotating the shaft member 2 synchronizing with rotation of the said steering.

  In addition, on the outer wall surface of the first recess 2c, first and second placement surfaces 2f and 2g each having a step shape are formed below the tip portion 2e, and are adjacent to the tip portion 2e. The first placement surface 2f is a step for placing the inner edge portion of the washer, and the second placement surface 2g positioned at a level lower than the first placement surface 2f is an O described later. It is for mounting a ring.

  On the other hand, in the second concave portion 2d of the substantially cylindrical cup, the projecting portion 1n having the housing portion 1f and the magnetic detection element 4 are housed, and the side-side inner wall surface formed of the substantially circular shape of the second concave portion 2d. In 2h, an annular recess 2i having an annular groove shape corresponding to the shape of the magnet 3 for accommodating the magnet 3 is formed.

  Note that 2j is a cylindrical outer peripheral surface constituting the outer wall surface of the second recess 2d, and this outer peripheral surface 2j is slightly larger than the circular outer peripheral surface constituting the outer peripheral surface of the second mounting surface 2g. The diameter is set to be small. The annular flat surface 2k that connects the cylindrical outer peripheral surface 2j and the cylindrical outer peripheral surface of the second mounting surface 2g is formed by the inner periphery of the magnetic member 6 when the shaft member 2 is housed in the housing 1. It becomes the structure supported by the side upper end surface. In other words, the annular flat surface 2k abuts the upper end surface on the inner peripheral side of the magnetic member 6 at a predetermined position when the shaft member 2 is housed in the housing 1, so that the thrust direction of the shaft member 2 (the rotation of the shaft member 2). It functions as a restricting part that restricts movement in the direction of the central axis).

  Reference numeral 10 denotes an O-ring mounted on the second mounting surface 2g formed on the outer wall surface of the first recess 2c in the shaft member 2, and the O-ring 10 includes the mounting surface 2g. , Embedded in a gap surrounded by the side surface 2m connecting the mounting surfaces 2f and 2g and the inner wall surface 1s of the upper end 1b of the housing 1 to prevent foreign substances such as water from entering the rotation angle detection device A. It has a function to do. The O-ring 10 has an annular flat surface 2k that connects the outer peripheral surface 2j of the second recess 2d in the shaft member 2 and the circular outer peripheral surface of the second mounting surface 2g on the inner peripheral side of the magnetic member 6. After the shaft member 2 is accommodated in the housing 1 so as to abut the end surface, it is embedded in the gap. Further, instead of the O-ring 10 having a circular cross section, an X ring having an X cross section or a Y ring having a Y cross section may be employed.

  Reference numeral 11 denotes a washer. The washer 11 is made of a thermoplastic resin material such as polybutylene terephthalate in the same manner as the housing 1. This washer 11 is used to prevent the shaft member 2 from coming off, and holds the shaft member 2 in the first storage portion 1i. The washer 11 is placed on a first placement surface 2 f formed on the outer wall surface of the first recess 2 c in the shaft member 2 and a receiving portion 1 k provided on the upper end portion 1 b of the housing 1. The washer 11 is caulked and fixed by the caulking portion 1c on the mounting surface 2f and the receiving portion 1k so as to cover the O-ring 10 after the O-ring 10 is embedded in the gap. Specifically, the washer 11 is caulked after its inner edge side bottom surface portion is supported by the first mounting surface 2 f of the shaft member 2 and its outer edge side bottom surface portion is supported by the receiving portion 1 k of the housing 1. The shaft member 2 is caulked and fixed to the housing 1 by bending the portion 1c to a later-described center axis side of the shaft member 2 (in other words, the washer 11 side).

The washer 11 has a linear expansion coefficient of 0.9 to 1.3 (× 10 ⁻⁶ / ° C.). The housing 1 has the same linear expansion coefficient of 0.9 to 1.3 (× 10 ⁻⁶ / ° C.). Since the linear expansion coefficient is equal or close, the linear thermal expansion coefficient of the housing 1 and the washer 11 is the same or almost the same even when the surrounding environment is in a low sound and high temperature state. Wear does not occur at the contact position of the housing 1 and the washer 11, prevents generation of wear powder, prevents deterioration of slidability between the shaft member 2 and the first storage portion 1i due to wear powder, and improves detection accuracy. Can prevent adverse effects.

  In addition, by providing the first storage portion 1i with the projection 1q into which the washer 11 is press-fitted, the washer 11 is held in the first storage portion 1i with a small contact area, so that wear can be prevented. .

  The magnet 3 is formed in a substantially annular shape and is dipole magnetized. Further, the magnet 3 is fixed in the annular recess 2i of the second recess 2d in the shaft member 2 so as to surround the magnetism detection element 4 (a portion of the magnetism detection element 4 excluding a lead portion described later). And the rotation of the shaft member 2 around the rotation center axis L. This means that the rotation center axis of the magnet 3 substantially coincides with the rotation center axis L of the shaft member 2.

  The magnetic detection element 4 is formed of a detection element such as a Hall IC or an MR element, and is electrically connected to the circuit board 5 via the lead portion 4a and changes in magnetic force according to the rotation of the magnet 3 that rotates together with the shaft member 2. Is converted into a detection signal, and the detection signal is output to the outside through a terminal (not shown) mounted on the circuit board 5. Further, the magnetic detection element 4 is disposed such that its magnetic detection surface faces the inner wall surface (magnetization surface) of the magnet 3 via the housing portion 1 f of the housing 1.

  In the case of this embodiment, the magnetic detection element 4 is not on the rotation center axis L of the shaft member 2 but at a position deviated from the rotation center axis L of the shaft member 2, that is, from the rotation center axis L of the shaft member 2. It is disposed at a position separated by a fixed amount, and is positioned and fixed so as to come into contact with the inner wall surface of the housing portion 1 f in the housing 1. The magnetic detection element 4 may be disposed on the rotation center axis L of the shaft member 2, but in consideration of the output characteristics (linearity) of the detection signal (output voltage) output from the magnetic detection element 4. The magnetic detection element 4 is preferably disposed at a position deviating from the rotation center axis L of the shaft member 2. This means that the linearity of the output voltage is improved when the magnetic detection element 4 is disposed not on the rotation center axis L but at a position away from the rotation center axis L.

  The circuit board 5 is made of, for example, a hard circuit board, is disposed along the back surface of the connecting portion 1 h of the housing 1, and is housed and fixed in a space portion 1 m that is an internal space of the annular wall portion 1 e in the housing 1. . Various electronic components such as the magnetic detection element 4, the terminal, and a capacitor are mounted on the circuit board 5. Reference numeral 5a denotes a hole through which the lead portion 4a of the magnetic detection element 4 passes.

  In the case of this embodiment, the circuit board 5 has a plurality of through-hole portions (not shown) through which a plurality of projecting pins (not shown) projecting downward (circuit board 5 side) from the bottom surface of the connecting portion 1h of the housing 1 pass. It has. Accordingly, when the circuit board 5 on which the magnetic detection element 4 is mounted is fixed to the housing 1, the protruding pins formed integrally with the connecting part 1h are passed through the through-hole parts of the circuit board 5, and the circuit What is necessary is just to heat-weld the protrusion edge part of each said protrusion pin which protrudes in the back side of the board | substrate 5. FIG.

  The magnetic member 6 is made of a magnetic material such as iron, is formed in a substantially cylindrical shape, and is fixed (held) to the annular groove portion 1 j of the housing 1 so as to surround the magnet 3. Further, the substantially cylindrical magnetic member 6 has a circular inner peripheral surface (circular inner wall surface) in contact with the outer peripheral surface 2j of the second recess 2d in the shaft member 2, so that the shaft member 2 is rotated. The shaft member 2 has a function as a shaft support member (bearing member) that rotatably supports the shaft member 2.

  In the case of the present embodiment, the magnetic member 6 is disposed and fixed in the annular groove 1j of the housing 1 so as to cover the outer periphery of the ring-shaped magnet 3, so that the magnetic flux distribution of the magnet 3 is dipolar. In the inner space of the magnetized magnet 3, the magnetic flux is distributed so as to pass through the magnetic detection surface of the magnetic detection element 4 and passes through the magnetic member 6, so that no leakage magnetic flux leaks to the outside (periphery) of the magnetic member 6. . Thereby, the magnetic force which passes the magnetic detection element 4, in other words, the magnetic force utilized for detection becomes large compared with the case where the magnetic member 6 is not provided, and detection accuracy can be improved.

  Further, since the magnetic member 6 is disposed and fixed in the annular groove 1j of the housing 1 so as to cover the outer periphery of the ring-shaped magnet 3, the magnetic force generated from a predetermined external device or the like can be applied to the rotation angle detection device A. The magnetic force from the outside does not pass through the inside of the magnetic member 6 (that is, inside the magnet 3) although it selectively passes through the magnetic member 6. By providing the magnetic member 6, the magnetic flux of the magnet 3 is not affected by the external magnetic force. Therefore, the magnetic interference (that is, the magnetic property) that is inevitably generated when the magnetic member 6 is not provided. In the case where the member 6 is not provided, a magnetic angle caused by interference between the magnetic flux passing around the magnet 3 and the external magnetic flux) is prevented, and a rotation angle detecting device with good detection accuracy can be provided.

  The rotation angle detector A that outputs a detection signal corresponding to the rotation of the shaft member 2 (the detected body) is configured by the above-described units. In addition, as shown in FIG. 1, the space part 1m which is the internal space of the annular wall part 1e which accommodates the circuit board 5 in which the magnetic detection element 4 is mounted, and the space part 1m so as to accommodate the magnetic detection element 4 are communicated. The housing portion 1 f is filled with a filling member 7 made of a resin that hardens from a liquid made of epoxy, silicone, or the like to a solid, whereby the magnetic detection element 4 and the circuit board 5 are placed in the housing 1. It is designed to be stored and held in an airtight manner.

  As described above, in the present embodiment, the shaft member 2 is provided with the first placement portion 2f, the washer 11 is disposed on the placement portion 2f, and a portion 1b of the upper end portion of the first storage portion 1i is placed on the washer. By caulking in the 11 direction, the shaft member 2 is thrust-restricted with respect to the first storage portion 1i, and fluctuations in the thrust direction of the magnet 3 disposed on the shaft member 2 are restricted. Therefore, the detection accuracy can be improved, and the shaft member 2 can be prevented from falling off from the first storage portion 1i.

  The present invention can be used in a rotation angle detection device that detects the rotation angle of a detection object.

A rotation angle detection device 1 housing 1i hollow portion (first storage portion)
1m space part (second storage part)
1p opening 1q protrusion 2 shaft member 3 magnet 4 magnetic detection element 11 washer

Claims (2)

Rotation angle detection comprising: a magnet provided on a rotating shaft member; a magnetic detection element for detecting a change in magnetic force due to the rotation of the magnet; and a housing provided with a first storage portion that rotatably arranges the shaft member. In the apparatus, a resin washer is provided in the opening of the first storage portion so that the shaft member does not come out of the first storage portion, and the washer has the same or substantially the same linear expansion coefficient as that of the housing. A rotation angle detecting device. The rotation angle detection device according to claim 1, wherein a projection for press-fitting the washer is provided in the opening.

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