JP2014098655A - Stroke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroke sensor capable of accurately detecting a stroke position of a stroke body even in the case that a stroke length is long.SOLUTION: The stroke sensor comprises :a magnetic field detection part 3 provided on a fixed body; two parallel yokes 4,5 provided so as to sandwich the magnetic field detection part 3 from a stroke direction of the stroke body and provided in parallel with the stroke direction of the stroke body; a parallel magnetic field forming yoke 6 that is provided on the stroke body and in parallel with the stroke direction of the stroke body and that is provided so that its one surface faces the parallel yokes 4,5 to form a parallel magnetic field between the parallel magnetic field forming yoke 6 and the parallel yokes 4, 5; a magnetic path forming yoke 7 for forming a magnetic path between the other surface of the parallel magnetic field forming yoke 6 and one of the two parallel yokes 4, 5; and a magnet 2 provided between the magnetic path forming yoke 7 and the parallel yoke 5 or on the middle of the magnetic path forming yoke 7.

Description

  The present invention relates to a stroke sensor that detects a stroke position of a stroke body that strokes relative to a fixed body.

  Conventionally, a stroke sensor has been used to detect a stroke position (relative to a fixed body) of a stroke body that makes a stroke relative to the fixed body. In this specification, the stroke means a reciprocating movement in one direction, and the stroke position means a relative position of the stroke body with respect to the fixed body.

  As a conventional stroke sensor, for example, there is Patent Document 1.

  In the stroke sensor of Patent Document 1, a magnet is provided on the stroke body, and a magnetic field detection unit (Hall IC) is disposed so as to face the magnet, and the stroke position is detected from the strength of the magnetic field detected by the magnetic field detection unit. .

JP 2009-276230 A JP 2012-177453 A

  However, since the above-described stroke sensor of Patent Document 1 detects a magnetic field in space, the magnetic field detection unit cannot detect the magnetic field when the magnet is separated from the magnetic field detection unit. For this reason, the stroke sensor of Patent Document 1 has a problem that the stroke length of the stroke body that can be handled is short, and cannot cope with a long stroke length.

  For example, in an electromagnetic suspension of a vehicle, a stroke sensor is used to detect a relative displacement between a vehicle body side and a wheel side (see, for example, Patent Document 2), but in a stroke sensor used in this electromagnetic suspension, for example, It is necessary to correspond to a stroke length of about 150 to 200 mm, and it is difficult to cope with the above-described stroke sensor of Patent Document 1.

  Furthermore, in the above-described stroke sensor of Patent Document 1, it is necessary to process the magnet into a curved surface (in an arc shape) in order to make the relationship between the detection amount in the magnetic field detection unit and the stroke position linear. In addition, there is a problem that the cost becomes high.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a stroke sensor that can accurately detect the stroke position of a stroke body even when the stroke length is long.

  The present invention has been devised to achieve the above object, and is a stroke sensor for detecting a stroke position of a stroke body that makes a stroke relative to the fixed body, and a magnetic field detector provided in the fixed body. And two parallel yokes provided parallel to the stroke direction of the stroke body, and parallel to the stroke direction of the stroke body. A parallel magnetic field forming yoke for forming a parallel magnetic field with the parallel yoke, the other surface of the parallel magnetic field forming yoke, and the 2 A magnetic path forming yoke that forms a magnetic path with one of the two parallel yokes, and the magnetic path forming yoke and the one parallel yoke. Between the click or a magnet is provided in the middle of the magnetic path forming yoke, a stroke sensor having a.

  The magnetic field detection unit may detect a magnetic field parallel to the stroke direction of the stroke body.

  A magnetic leakage prevention layer made of a non-magnetic material may be provided between the magnetic field detector and the two parallel yokes and the fixed body.

  The magnet is provided between the magnetic path forming yoke and the parallel yoke, and the magnetic path forming yoke extends in parallel with the stroke direction of the stroke body from the end of the magnet opposite to the parallel yoke. It may be provided so as to face the other surface of the parallel magnetic field forming yoke.

  On the other surface of the parallel magnetic field forming yoke, a convex protruding yoke whose tip faces the magnetic path forming yoke may be integrally provided.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where stroke length is long, the stroke sensor which can detect the stroke position of a stroke body accurately can be provided.

It is a figure which shows the stroke sensor which concerns on one embodiment of this invention, (a) is a schematic block diagram, (b), (c) is a figure explaining the operation | movement. In this invention, it is a graph which shows an example of the relationship between the output of the magnetic field detection part 3, and the stroke position of a stroke body.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a stroke sensor according to the present embodiment, where (a) is a schematic configuration diagram, and (b) and (c) are diagrams for explaining the operation thereof.

  As shown in FIGS. 1A to 1C, the stroke sensor 1 detects a stroke position of a stroke body (not shown) that makes a stroke relative to a fixed body (not shown). , A magnet (permanent magnet) 2 and a magnetic field detection unit (magnetic detection element) 3.

  In the present embodiment, a case where the magnet 2 and the magnetic field detector 3 are provided on the fixed body will be described. Although it is possible to provide the magnet 2 and the magnetic field detector 3 in the stroke body, in this case, the electric wiring to the magnetic field detector 3 may be damaged by the stroke of the stroke body, and the member provided in the stroke body May increase and obstruct the stroke motion of the stroke body.

  The magnetic field detector 3 outputs a voltage or current corresponding to the strength of the magnetic field, and is, for example, a Hall IC.

  The stroke sensor 1 can be used as, for example, a stroke sensor of an electromagnetic suspension system for a vehicle that detects a relative displacement between a vehicle body side and a wheel side. In this case, the vehicle body side member (sprung member) in the electromagnetic suspension is a fixed body, and the wheel side member (unsprung member) is a stroke body.

  The stroke sensor 1 according to the present embodiment is configured so that the magnetic field detection unit 3 detects the magnitude of the magnetic field generated by the magnet 2 and guided through the yokes 4 to 8.

  More specifically, the stroke sensor 1 includes two parallel yokes 4, 5, a parallel magnetic field forming yoke 6, a magnetic path forming yoke 7, and a protruding yoke 8. Each yoke 4-8 consists of magnetic bodies.

  The parallel yokes 4 and 5 are provided so as to sandwich the magnetic field detector 3 from the stroke direction of the stroke body (vertical direction in FIG. 1). The magnetic field detector 3 and the parallel yokes 4 and 5 are fixed closely. The parallel yokes 4 and 5 are formed in a flat plate shape and are provided in parallel with the stroke direction of the stroke body. In the present embodiment, since the magnetic field detection unit 3 is provided on the fixed body, the parallel yokes 4 and 5 are also provided on the fixed body.

  As will be described in detail later, in the stroke sensor 1, the magnetic field guided from the parallel yoke 4 to the parallel yoke 5 is detected by the magnetic field detector 3. That is, the magnetic field detector 3 detects a magnetic field parallel to the stroke direction of the stroke body.

  The parallel magnetic field forming yoke 6 is formed in a flat plate shape, is provided on the stroke body in parallel with the stroke direction of the stroke body, and is provided so as to face the parallel yokes 4 and 5, and between the parallel yokes 4 and 5. Configured to form a parallel magnetic field.

  The magnetic path forming yoke 7 forms a magnetic path between the other surface of the parallel magnetic field forming yoke 6 and one of the two parallel yokes 4 and 5 (here, the lower parallel yoke 5).

  In the present embodiment, the magnet 2 is provided between the magnetic path forming yoke 7 and the parallel yoke 5, and the magnetic path forming yoke 7 is connected to the stroke direction of the stroke body from the end opposite to the parallel yoke 5 of the magnet 2. It extended in parallel and provided so that the other surface of the parallel magnetic field formation yoke 6 might be opposed. Thereby, both the magnetic path forming yoke 7 and the parallel yokes 4 and 5 are arranged in parallel along the stroke direction, and the parallel magnetic field forming yoke 6 is sandwiched between the magnetic path forming yoke 7 and the parallel yokes 4 and 5. It has become.

  Here, the magnet 2 is arranged so that the N pole of the magnet 2 is in contact with the magnetic path forming yoke 7 and the S pole is in contact with the parallel yoke 5, but the N pole and S pole of the magnet may be reversed. Since the magnetic path forming yoke 7 is fixed to the magnet 2, it is provided on the fixed body.

  In this embodiment, the magnetic path forming yoke 7 is configured to form a magnetic path between the other surface of the parallel magnetic field forming yoke 6 and the parallel yoke 5. Of course, it is possible to configure the magnetic path forming yoke 7 so as to form a magnetic path between the surface and the parallel yoke 4. In this case, the magnet 2 is disposed between the magnetic path forming yoke 7 and the parallel yoke 4.

  Furthermore, in the present embodiment, the magnet 2 is provided between the magnetic path forming yoke 7 and the parallel yoke 5, but the present invention is not limited thereto, and the magnet 2 may be provided in the middle of the magnetic path forming yoke 7. . In this case, the magnetic path forming yoke 7 is divided into two parts, and the magnet 2 is provided between the two divided magnetic path forming yokes 7.

  Furthermore, in the present embodiment, a convex protruding yoke 8 whose tip faces the magnetic path forming yoke 7 is integrally provided on the other surface of the parallel magnetic field forming yoke 6. The protrusion yoke narrows the interval between the parallel magnetic field forming yoke 6 and the magnetic path forming yoke 7 so that the magnetic field is easily transmitted between the parallel magnetic field forming yoke 6 and the magnetic path forming yoke 7. If the distance between the parallel magnetic field forming yoke 6 and the magnetic path forming yoke 7 is sufficiently narrow, the protruding yoke 8 can be omitted.

  Although not shown, the stroke sensor 1 includes a stroke position calculation unit that calculates the stroke position based on the output of the magnetic field detection unit 3. The stroke position calculation unit is mounted on a calculation device such as an electronic control unit (ECU) of a vehicle, for example.

  Next, the operation of the stroke sensor 1 will be described.

  As shown in FIG. 1A, in the stroke sensor 1, the magnetic field generated by the magnet 2 is guided from the N pole of the magnet 2 through the magnetic path forming yoke 7 and the protruding yoke 8 to the parallel magnetic field forming yoke 6. It becomes a parallel magnetic field and is guided to the parallel yokes 4 and 5.

  At this time, the magnetic field from the parallel magnetic field forming yoke 6 in the portion facing the parallel yoke 4 passes through the parallel yoke 4, the magnetic field detector 3, and the parallel yoke 5, and returns to the S pole of the magnet 2. On the other hand, the magnetic field from the parallel magnetic field forming yoke 6 facing the parallel yoke 5 returns to the S pole of the magnet 2 through the parallel yoke 5 without passing through the magnetic field detector 3.

  Therefore, as shown in FIG. 1B, when the stroke body strokes toward the parallel yoke 5 and the area of the parallel magnetic field forming yoke 6 facing the parallel yoke 4 is reduced, the strength of the magnetic field passing through the magnetic field detecting unit 3 is reduced. Becomes weaker. On the other hand, as shown in FIG. 1C, when the stroke body strokes toward the parallel yoke 4 and the area of the parallel magnetic field forming yoke 6 facing the parallel yoke 4 increases, the strength of the magnetic field passing through the magnetic field detector 3 is increased. Become stronger.

  Since the magnetic field detector 3 outputs a voltage or current corresponding to the intensity of the magnetic field, if the relationship between the output of the magnetic field detector 3 and the stroke position of the stroke body is obtained in advance, the relationship and the magnetic field detector The stroke position of the stroke body can be obtained based on the output of No. 3.

  An example of the relationship between the output of the magnetic field detector 3 and the stroke position of the stroke body is shown in FIG. As shown in FIG. 2, the output of the magnetic field detector 3 and the stroke position of the stroke body are in a proportional relationship. The left and right stroke positions of the horizontal axis represent the parallel yoke 5 side and the right side represents the parallel yoke 4 side.

  In the stroke sensor 1, when the entire parallel magnetic field forming yoke 6 faces the parallel yoke 4, the magnetic field detected by the magnetic field detection unit 3 is maximized, and even if the stroke body further strokes toward the parallel yoke 4, the magnetic field detection is performed. The magnetic field detected by the unit 3 does not change. Similarly, when the entire parallel magnetic field forming yoke 6 faces the parallel yoke 5, the magnetic field detected by the magnetic field detection unit 3 is minimized (approximately 0), and even if the stroke body further strokes toward the parallel yoke 5, the magnetic field detection is performed. The magnetic field detected by the unit 3 does not change.

  That is, the stroke sensor 1 can detect the stroke position from the stroke position where the entire parallel magnetic field forming yoke 6 faces the parallel yoke 4 to the stroke position where the entire parallel magnetic field forming yoke 6 faces the parallel yoke 5. is there. Therefore, for example, the parallel magnetic field forming yoke 6 as a whole is opposed to the parallel yoke 4 at the position where the stroke body strokes most toward the parallel yoke 4 side, and the parallel magnetic field forming yoke is located at the position where the stroke body strokes most toward the parallel yoke 5 side. By determining the sizes of the yokes 4 to 7 so that the entire 6 faces the parallel yoke 5, the stroke position can be detected in the entire stroke length of the stroke body.

  In addition, the size of each yoke 4-7 can be suitably set according to the length (stroke length) which can detect a stroke position. However, the length of the parallel magnetic field forming yoke 6 needs to be longer than the length that enables detection of the stroke position.

  In addition, when the magnetic field detector 3 and the parallel yokes 4 and 5 are attached to the fixed body, if a magnetic body exists in the immediate vicinity of the magnetic field detector 3 and the parallel yokes 4 and 5, a part of the magnetic field is guided to the magnetic body. As a result, the stroke position cannot be accurately detected. Therefore, in order to prevent such a problem, it is desirable to provide a magnetic leakage prevention layer made of a non-magnetic material between the magnetic field detector 3 and the two parallel yokes 4 and 5 and the fixed body.

  The operation of the present embodiment will be described.

  In the stroke sensor 1 according to the present embodiment, the magnetic field detection unit 3 provided on the fixed body and the magnetic field detection unit 3 are provided so as to be sandwiched from the stroke direction of the stroke body, and are provided in parallel with the stroke direction of the stroke body. Two parallel yokes 4 and 5 are provided on the stroke body in parallel with the stroke direction of the stroke body, and one surface is provided so as to face the parallel yokes 4 and 5. A parallel magnetic field forming yoke 6 for forming a parallel magnetic field, a magnetic path forming yoke 7 for forming a magnetic path between the other surface of the parallel magnetic field forming yoke 6 and one of the two parallel yokes 4 and 5, and a magnetic path A magnet 2 provided between the forming yoke 7 and one of the parallel yokes 5 or in the middle of the magnetic path forming yoke 7 is provided.

  By using the yokes 4 to 7, it becomes possible to detect the magnetic field by the magnetic field detection unit 3 even when the magnet 2 and the magnetic field detection unit 3 are separated from each other as compared to the case of detecting the magnetic field in the space as in the past. Even when the stroke length is long, the stroke sensor 1 capable of accurately detecting the stroke position of the stroke body can be realized.

  Further, in the stroke sensor 1, a linear output can be obtained by the magnetic field detection unit 3 without performing special processing such as forming a curved surface on the magnet 2, so that the stroke sensor 1 is compared with the conventional technique that forms a curved surface on the magnet 2. Cost reduction is possible.

  Furthermore, it is desirable to reduce the number of members provided in the stroke body as much as possible so as not to obstruct the stroke motion of the stroke body as much as possible. However, in the stroke sensor 1, both the magnet 2 and the magnetic field detection unit 3 can be provided on the fixed body. Since only the parallel magnetic field forming yoke 6 has to be provided on the stroke body, the number of members provided on the stroke member can be reduced, and inhibition of the stroke motion of the stroke body can be suppressed.

  The stroke sensor 1 is particularly preferably used when the stroke length of a stroke body whose stroke position is to be detected is long, such as a stroke sensor of an electromagnetic suspension system of a vehicle that detects a relative displacement between a vehicle body side and a wheel side. Can do.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Stroke sensor 2 Magnet 3 Magnetic field detection part 4, 5 Parallel yoke 6 Parallel magnetic field formation yoke 7 Magnetic path formation yoke 8 Protrusion yoke

Claims (5)

A stroke sensor that detects a stroke position of a stroke body that strokes relative to a fixed body,
A magnetic field detector provided on the fixed body;
Two parallel yokes provided so as to sandwich the magnetic field detector from the stroke direction of the stroke body, and provided in parallel with the stroke direction of the stroke body;
A parallel magnetic field forming yoke which is provided on the stroke body in parallel with the stroke direction of the stroke body and has one surface facing the parallel yoke to form a parallel magnetic field with the parallel yoke;
A magnetic path forming yoke that forms a magnetic path between the other surface of the parallel magnetic field forming yoke and one of the two parallel yokes;
A magnet provided between the magnetic path forming yoke and the one parallel yoke or in the middle of the magnetic path forming yoke;
A stroke sensor characterized by comprising: The stroke sensor according to claim 1, wherein the magnetic field detection unit detects a magnetic field parallel to a stroke direction of the stroke body. The stroke sensor according to claim 1, wherein a magnetic leakage prevention layer made of a nonmagnetic material is provided between the magnetic field detection unit, the two parallel yokes, and the fixed body. The magnet is provided between the magnetic path forming yoke and the parallel yoke,
The magnetic path forming yoke is provided so as to extend in parallel with the stroke direction of the stroke body from an end of the magnet opposite to the parallel yoke and to face the other surface of the parallel magnetic field forming yoke. Item 4. The stroke sensor according to any one of Items 1 to 3. The stroke sensor according to claim 4, wherein a convex protrusion yoke having a tip thereof facing the magnetic path forming yoke is integrally provided on the other surface of the parallel magnetic field forming yoke.

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