Stroke sensor and braking system using the same

Abstract

To improve the accuracy of measuring the direction of a magnetic field, in a stroke sensor.SOLUTION: A stroke sensor 1 comprises: a magnetic field detection element 2 detecting a magnetic field; a magnet 3 which generates a magnetic field to be detected by the magnetic field detection element 2, and which relatively moves in a first direction X with respect to the magnetic field detection element 2; and a first soft magnetic material 4A having fixed relative position with respect to the magnetic field detection element 2. The magnetic field detection element 2 and the first soft magnetic material 4A are spaced apart from the magnet 3 in a second direction Z orthogonal to the first direction X. The first soft magnetic material 4A is positioned at a side of the magnetic field detection element 2 in the first direction X. When a third direction Y is denoted as a direction orthogonal to the first and second direction Z, L1 is denoted as the dimension of the first soft magnetic material 4A in the first direction X, the dimension of the first soft magnetic material 4A in the second direction Z is denoted as D1, and the dimension of the first soft magnetic material 4A in the third direction Y is denoted W1, then L1>D1 and L1>W1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a stroke sensor and a braking system using the same.

Background Art

[0002] Generally, a stroke sensor detects the direction of a magnetic field to detect the presence or absence of movement of an object to be measured and the moving distance. Patent Document 1 discloses a stroke sensor having a magnetic field detection element that detects a magnetic field, a magnet that generates a magnetic field detected by the magnetic field detection element, and that moves relative to the magnetic field detection element. The stroke sensor disclosed in Patent Document 1 has soft magnetic bodies on both sides in the relative movement direction of the magnetic field detection element. Patent Document 1 describes that by providing the soft magnetic bodies, the magnetic flux density can be increased and the stroke can be increased.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a stroke sensor, it is important to increase the magnetic flux density detected by the magnetic field detection element, but it is also important to improve the measurement accuracy of the direction of the magnetic field.

[0005] An object of the present invention is to provide a stroke sensor capable of improving the measurement accuracy of the direction of a magnetic field.

Means for Solving the Problems

[0006] The stroke sensor of the present invention includes a magnetic field detection element that detects a magnetic field, a magnet that generates the magnetic field detected by the magnetic field detection element and moves relative to the magnetic field detection element in a first direction, and a first soft magnetic body whose relative position with respect to the magnetic field detection element is fixed. Detect the relative movement amount in the first direction of the magnetic field detection element of the magnet from the direction of the magnetic field The magnetic field detection element and the first soft magnetic body are separated from the magnet in a second direction orthogonal to the first direction. The first soft magnetic body is located on the side of the magnetic field detection element in the first direction as viewed from the second direction. When the direction orthogonal to the first and second directions is the third direction, the dimension of the first soft magnetic body in the first direction is L1, the dimension of the first soft magnetic body in the second direction is D1, and the dimension of the first soft magnetic body in the third direction is W1, then L1 > D1 and L1 > W1.

Effect of the Invention

[0007] According to the present invention, it is possible to provide a stroke sensor capable of improving the measurement accuracy of the direction of a magnetic field.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 17

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, embodiments of the stroke sensor of the present invention and a brake system using the same will be described. In the following description, the direction in which the magnet 3 moves relative to the magnetic field detection element 2 is the first direction X, which is orthogonal to the first direction X, and the direction in which the magnetic field detection element 2, the first soft magnetic body 4A, and the second soft magnetic body 4B are separated from the magnet 3 is the second direction Z, and the direction orthogonal to the first direction X and the second direction Z is the third direction Y.

[0010] (First Embodiment) Fig. 1 shows a schematic diagram of the stroke sensor 1 according to the first embodiment of the present invention. Fig. 1(a) is a perspective view of the stroke sensor 1, Fig. 1(b) is a side view of the stroke sensor 1 as viewed from the third direction Y, and Fig. 1(c) is a plan view of the stroke sensor 1 as viewed from the second direction Z. The stroke sensor 1 includes a magnetic field detection element 2 that detects a magnetic field, and a magnet 3 that generates a magnetic field detected by the magnetic field detection element 2. The magnet 3 is attached to a movable member 13 that is movable in the first direction X, and moves in the first direction X together with the movable member 13. The magnetic field detection element 2 is attached to a fixed member (not shown). Therefore, the magnet 3 moves relative to the magnetic field detection element 2 in the first direction X. The magnet 3 may be attached to the fixed member and the magnetic field detection element 2 may be attached to the movable member 13.

[0011] The magnetic field detection element 2 includes a first element (not shown) that detects the magnetic flux density Bx in the first direction X, and a second element (not shown) that detects the magnetic flux density Bz in the second direction Z. The type of the element is not limited, and in addition to the Hall element, magnetoresistive effect elements such as AMR elements and TMR elements can be used. The arithmetic unit (not shown) of the stroke sensor 1 calculates the angle of the synthetic magnetic field (vector sum of Bx and Bz) from the magnetic flux densities detected by the first element and the second element. Since the magnetic field distribution around the magnet 3 has been obtained in advance, the relative displacement of the magnet 3, that is, the amount of movement of the movable member 13 in the first direction X can be detected from the direction of the synthetic magnetic field.

[0012] The magnet 3 is formed of a magnetic material such as neodymium. The magnet 3 is magnetized in the first direction X. A configuration example of the magnet 3 is shown in FIG. 2. As shown in FIGS. 1(a) and 2(a), the shape of the magnet 3 in the present embodiment is a cylindrical shape having a central axis C parallel to the first direction X. The movable member 13 is a cylindrical or rod-shaped member, and its central axis C coincides with the central axis C of the magnet 3. The movable member 13 is inserted into the central hole 31 of the magnet 3, and the magnet 3 is fixed to the movable member 13 by appropriate means such as an adhesive or a screw at a predetermined position of the movable member 13. As shown in FIG. 2(b), the shape of the magnet 3 may be a cylindrical shape having a central axis C parallel to the first direction X. In this case, the magnet 3 is fixed to the end of the movable member 13 by appropriate means such as an adhesive or a screw. As shown in FIG. 2(c), the magnet 3 may be attached to a part of the circumferential surface of the movable member 13. In this case, the movable member 13 preferably has a rectangular cross section, and the magnet 3 is a rectangular parallelepiped. When the movable member 13 rotates around the central axis C, the magnetic flux distribution generated around the magnet 3 does not change for the cylindrical or cylindrical magnet 3. Therefore, when the movable member 13 is rotatable around the central axis C, the configurations shown in FIGS. 2(a) and 2(b) are advantageous. On the other hand, when the rotation of the movable member 13 around the central axis C is restricted, the configuration shown in FIG. 2(c) may be selected from the viewpoint of processing cost and the like.

[0013] On both sides of the magnetic field detection element 2 in the first direction X, a first soft magnetic body 4A and a second soft magnetic body 4B are provided. More specifically, the first soft magnetic body 4A is located on the side of the magnetic field detection element 2 in the first direction X as viewed from the second direction Z, and the second soft magnetic body 4B is on the side of the magnetic field detection element 2 in the first direction X as viewed from the second direction Z and is located on the side opposite to the first soft magnetic body 4A with respect to the magnetic field detection element 2. The relative positions of the first soft magnetic body 4A and the second soft magnetic body 4B with respect to the magnetic field detection element 2 are fixed. The first soft magnetic body 4A and the second soft magnetic body 4B are rectangular parallelepipeds, and each side of the rectangular parallelepiped is parallel to any one of the first direction X, the second direction Z, and the third direction Y. The first soft magnetic body 4A and the second soft magnetic body 4B are formed of a soft magnetic material such as a general steel material. The first soft magnetic body 4A and the second soft magnetic body 4B are preferably formed of the same material. The magnetic field detection element 2, the first soft magnetic body 4A, and the second soft magnetic body 4B are separated from the magnet 3 in the second direction Z. The first soft magnetic body 4A and the second soft magnetic body 4B are spaced apart from the magnetic field detection element 2 in the first direction X. The first soft magnetic body 4A and the second soft magnetic body 4B are mirror-symmetrical with respect to a plane passing through the center 21 of the magnetizing portion of the magnetic field detection element 2 and parallel to the second direction Z and the third direction Y. The center 21 of the magnetizing portion of the magnetic field detection element 2 is the center of the semiconductor thin film (InSb thin film, GaAs thin film, etc.) constituting the Hall element in the case of a Hall element, the center of the ferromagnetic metal thin film constituting the AMR element in the case of an AMR element, and the center of the free layer in the case of a TMR element or a GMR element.

[0014] Here, the definitions of the dimensions used in the following description are described (see also Fig. 1(b)). L1: Dimension (length) of the first soft magnetic body 4A in the first direction X D1: Dimension (thickness) of the first soft magnetic body 4A in the second direction Z W1: Dimension (width) of the first soft magnetic body 4A in the third direction Y L2: Dimension (length) of the second soft magnetic body 4B in the first direction X D2: Dimension (thickness) of the second soft magnetic body 4B in the second direction Z W2: Dimension (width) of the second soft magnetic body 4B in the third direction Y G1: Spacing between the magnetic field detection element 2 and the first soft magnetic body 4A in the first direction X G2: Spacing between the magnetic field detection element 2 and the second soft magnetic body 4B in the first direction X H1: Interval in the second direction Z between the center 41 of the first soft magnetic body 4A and the center 21 of the magnetic sensing portion of the magnetic field detection element 2 (assuming the direction in which the first soft magnetic body 4A and the magnetic field detection element 2 move away from the magnet 3 is positive, and the direction approaching the magnet 3 is negative) H2: Interval in the second direction Z between the center 42 of the second soft magnetic body 4B and the center 21 of the magnetic sensing portion of the magnetic field detection element 2 (assuming the direction in which the second soft magnetic body 4B and the magnetic field detection element 2 move away from the magnet 3 is positive, and the direction approaching the magnet 3 is negative) S: Range in which the center (center of gravity) 31 of the magnet 3 can move relative to the center 21 of the magnetic sensing portion of the magnetic field detection element 2, or the maximum value of the relative movable distance (also referred to as the stroke) S1: Distance that the magnet 3 can move relative to the reference position R towards the side of the first soft magnetic body 4A S2: Distance that the magnet 3 can move relative to the reference position R towards the side of the second soft magnetic body 4B T: Length of the smallest interval including the first soft magnetic body 4A and the second soft magnetic body 4B in the first direction X (also referred to as the soft magnetic body arrangement length) T1: Length of the smallest interval including the first soft magnetic body 4A and the reference position in the first direction X T2: Length of the smallest interval including the second soft magnetic body 4B and the reference position in the first direction X The magnet 3 moves relative to the magnetic field detection element 2 with the reference position R as the center. The reference position R is the relative position of the magnet 3 with respect to the magnetic field detection element 2 (hereinafter sometimes referred to as the relative position of the magnet 3), and is the position where the center 31 of the magnet 3 coincides with the center 21 of the magnetic sensing portion of the magnetic field detection element 2 in the first direction X.

[0015] In this embodiment, L1 = L2 = 17 mm, D1 = D2 = 1 mm, W1 = W2 = 5 mm, and L1 > D1, L1 > W1, and L2 > D2, and L2 / W2 holds. That is, the first soft magnetic body 4A and the second soft magnetic body 4B have an elongated shape in the first direction X. Regarding the relationship between D1 and W1, D1 ≤ W1, and preferably D1 < W1. Similarly, regarding the relationship between D2 and W2, D2 ≤ W2, and preferably D2 < W2. That is, the first soft magnetic body 4A and the second soft magnetic body 4B have a flat shape in the second direction Z. The reference position R is located at the center of the stroke S, and S1 = S2 = S / 2. Also, S = T, and S1 = T1, S2 = T2. That is, when the center 31 of the magnet 3 is located at one end of the stroke S, the center 31 of the magnet 3 and the outer end of the first soft magnetic body 4A coincide in the first direction X, and when the center 31 of the magnet 3 is located at the other end of the stroke S, the center 31 of the magnet 3 and the outer end of the second soft magnetic body 4B coincide in the first direction X.

[0016] By providing such a first soft magnetic body 4A and a second soft magnetic body 4B, it is possible to correct the direction of the magnetic flux generated by the magnet 3 and measure the direction of the magnetic field with higher accuracy. Here, the direction of the magnetic field and its measurement error will be described with reference to FIG. 3. The upper diagram in FIG. 3 shows the magnet 3 (shown by a solid line) at the reference position R and the magnets 3 at both ends of the stroke S (shown by a dashed line). The arrows schematically show the direction of the magnetic flux. The middle diagram in FIG. 3 shows the relationship between the relative position of the magnet 3 and the angle of the magnetic flux lines (magnetic force lines) at the center 21 of the magnetically sensitive part of the magnetic field detection element 2. The angle is defined as 0 degrees at 9 o'clock of the clock and positive in the counterclockwise direction as shown in FIG. 3.

[0017] As described above, the stroke sensor 1 detects the movement amount of the magnet 3 in the first direction X from the angle of the synthetic magnetic field (vector sum of Bx and Bz) detected by the magnetic field detection element 2, that is, the angle of the magnetic flux lines. Therefore, in order to detect the movement amount in the first direction X with higher accuracy, it is desirable that the linearity between the relative position of the magnet 3 and the angle of the magnetic flux lines at the center 21 of the magnetically sensitive portion of the magnetic field detection element 2 is high (the linearity of the graph in the figure in FIG. 3 is high). If the linearity is low, the measurement accuracy decreases in a region where the change in the angle of the magnetic flux lines is small. Furthermore, if the linearity decreases, the angles of the magnetic flux lines become the same value at a plurality of relative positions, making the measurement itself difficult. Here, the relationship between the relative position of the magnet 3 and the angle θB of the magnetic flux lines at the center 21 of the magnetically sensitive portion of the magnetic field detection element 2 is linearly approximated by the least squares method between the minimum value θB1 and the maximum value θB2 of the actual angle of the magnetic flux lines. Assuming the difference between the actual angle θB of the magnetic flux lines and the angle θBo of the magnetic flux lines on the linear approximation line as ΔθB = θB - θBo, the error θBerror is obtained as ΔθB / (θB2 - θB1). The figure below FIG. 3 shows the relationship between the relative position of the magnet 3 and the error θBerror. In the present embodiment, it is possible to reduce the error θBerror obtained in this way. Hereinafter, the present embodiment will be further described by way of examples and comparative examples.

[0018] In the stroke sensor 1 of Example 1, the magnet 3 moves relatively within a range of 23 mm on both sides of the reference position R. In the following description, the relative displacement of the magnet 3 is set to 0 at the reference position R, negative on the left side of the reference position R, and positive on the right side of the reference position R. Figures 4(a) to 4(d) conceptually show the directions of magnetic flux lines when the magnet 3 is at several relative positions (-23 m, -16 mm, -8 mm, 0 mm) with respect to the reference position R. Figure 5(a) shows the relationship between the relative position of the magnet 3 and the angle θB of the magnetic flux lines at the center 21 of the magnetically sensitive part of the magnetic field detection element 2, and Figure 5(b) shows the relationship between the relative position of the magnet 3 and the error θBerror. The solid line represents Example 1, and the dashed line represents a comparative example in which the first soft magnetic body 4A and the second soft magnetic body 4B are removed from Example 1. In Example 1, the linearity between the relative position of the magnet 3 and the angle θB of the magnetic flux lines is high, and an almost linear graph is obtained. In contrast, in the comparative example, the error θerror is particularly large at the relative position B (-16 mm). Referring to Figure 4(b) corresponding to the relative position B, in the comparative example, the way the magnetic flux lines bend counterclockwise (the change in θB) is slow, which is the cause of the error θerror. In contrast, in Example 1, it can be seen that the magnetic flux lines bend smoothly and the change in θB can follow the change in the relative position well.

[0019] Figure 6 shows an analysis example of the magnetic flux in the vicinity of the magnet 3 and the magnetic field detection element 2. Figure 6(a) is Example 1, and although not shown, the second soft magnetic body 4B is also provided. Figure 6(b) is the comparative example. The position corresponding to the first soft magnetic body 4A is indicated by a square. The relative position of the magnet 3 corresponds to Figure 4(b). In the comparative example, the magnetic flux is generally sinusoidal, whereas in Example 1, a part of the magnetic flux is pulled and sucked into the first soft magnetic body 4A. As a result, it is considered that the magnetic flux rotates greatly counterclockwise in the vicinity of the magnetic field detection element 2.

[0020] FIG. 5(c) shows the relationship between the relative position of the magnet 3 and the magnetic flux density (absolute value). The magnetic flux density increases when the magnet 3 is near the reference position R. The magnetic flux density is slightly larger in Example 1 than in the comparative example near the reference position R, but the comparative example is slightly larger than Example 1 at positions far from the reference position R, and there is no significant difference. It can be seen that the first and second soft magnetic bodies 4A and 4B have little effect on increasing the magnetic flux density and mainly function to reduce the error θBerror.

[0021] As described above, in the present embodiment, the first soft magnetic body 4A and the second soft magnetic body 4B have an elongated shape in the first direction X. FIG. 5 also shows Example 2 by a dotted line. In Example 2, the dimensions of the first soft magnetic body 4A and the second soft magnetic body 4B are L1 = L2 = 5.5 mm, D1 = D2 = 1 mm, W1 = W2 = 5 mm, and L1 > D1, L1 > W1, and L2 > D2, L2 / W2 holds. As shown in FIGS. 5(a) and 5(b), in Example 2, the linearity of the angle θB and the error θerror are inferior to those in Example 1. This is presumably because when the dimensions L1 and L2 of the first soft magnetic body 4A and the second soft magnetic body 4B in the first direction X are small, the effect of pulling the magnetic flux and changing the direction of the magnetic flux is small. However, in Example 2, the linearity of the angle θB and the error θerror are improved compared to the comparative example. From this, it is understood that the error θerror is reduced if L1 > D1, L1 > W1, and L2 > D2, L2 / W2. On the other hand, the magnetic flux density when the magnet 3 is near the reference position R is larger in Example 2 than in Example 1 and the comparative example. Therefore, the magnetic flux density required for the operation of the stroke sensor 1 can be ensured in a wider movement range. For example, in FIG. 5(c), the range of the position of the magnet 3 where a magnetic flux density of 50 mT or more can be obtained is A for Example 1 and B for Example 2, and Example 2 can ensure a larger stroke than Example 1. It is considered that almost the same effect as in Example 2 can be obtained in the range where 1 < L1 / W1 ≦ 1.2 and 1 < L2 / W2 ≦ 1.2. Also, almost the same effect as in Example 1 can be obtained in the range where 3 ≦ L1 / W1 ≦ 4 and 3 ≦ L2 / W2 ≦ 4.

[0022] In order to further reduce the error θerror, it is preferable to make the ratio of the stroke S to the soft magnetic body arrangement length T as close to 1 as possible (for example, 0.95 ≦ T / S ≦ 1.05). Fig. 7 shows the relationship between the soft magnetic body arrangement length T and the error θerror when the stroke S is fixed (46 mm). When the soft magnetic body arrangement length T is larger than the stroke S, magnetic flux lines are absorbed by the first soft magnetic body 4A and the second soft magnetic body 4B outside the range of the stroke S, and the direction of the magnetic flux lines is disturbed. Conversely, when the soft magnetic body arrangement length T is smaller than the stroke S, near the ends of the stroke S, the first soft magnetic body 4A and the second soft magnetic body 4B pull the magnetic flux, and the effect of changing the direction of the magnetic flux cannot be obtained. The error θerror is minimized when the stroke S and the soft magnetic body arrangement length T are equal. When the soft magnetic body arrangement length T is 32 mm or more and 69 mm or less, that is, 0.69 ≦ T / S ≦ 1.5, the error θerror is 2% or less. When the soft magnetic body arrangement length T is 40 mm or more and 56 mm or less, that is, 0.89 ≦ T / S ≦ 1.22, the error θerror is 1% or less.

[0023] Fig. 8 shows the relationship between the dimensions D1, D2 of the first and second soft magnetic bodies 4A, 4B and the error θerror. When 0.56 mm ≦ D1 ≦ 3 mm and 0.56 mm ≦ D2 ≦ 3 mm, the error θerror is 2% or less. When 0.81 mm ≦ D1 ≦ 2.39 mm and 0.81 mm ≦ D2 ≦ 2.39 mm, the error θerror is 1% or less.

[0024] Fig. 9 shows the relationship between the dimensions W1, W2 of the first and second soft magnetic bodies 4A, 4B and the error θerror. When 2.51 mm ≦ W1 ≦ 10 mm and 2.51 mm ≦ W2 ≦ 10 mm, the error θerror is 2% or less. When 3.53 mm ≦ W1 ≦ 10 mm and 3.53 mm ≦ W2 ≦ 10 mm, the error θerror is 1% or less.

[0025] Fig. 10 shows the relationship between the separation distances G1, G2 between the magnetic field detection element 2 and the first and second soft magnetic bodies 4A, 4B and the error θerror. When 4.1 mm ≦ G1 ≦ 7.6 mm and 4.1 mm ≦ G2 ≦ 7.6 mm, the error θerror is 2% or less. When 5.1 mm ≦ G1 ≦ 6.7 mm and 5.1 mm ≦ G2 ≦ 6.7 mm, the error θerror is 1% or less.

[0026] Figure 11 shows the relationship between the distances H1 and H2 in the second direction Z between the centers 42 of the first and second soft magnetic bodies 4A and 4B and the center 21 of the magnetically sensitive portion of the magnetic field detection element 2, and the error θerror. When -3.5 mm ≤ H1 ≤ 1.0 mm and -3.5 mm ≤ H2 ≤ 1.0 mm, the error θerror is 1% or less. In the second direction Z, the center 21 of the magnetically sensitive portion of the magnetic field detection element 2 preferably overlaps with the first and second soft magnetic bodies 4A and 4B.

[0027] (Second Embodiment) Figure 12 shows a schematic diagram of the stroke sensor 1 according to the second embodiment of the present invention. Hereinafter, the differences from the first embodiment will be described. The configurations and effects for which the description is omitted are the same as those in the first embodiment. In the present embodiment, the length L1 of the first soft magnetic body 4A in the first direction X is smaller than the length L2 of the second soft magnetic body 4B in the first direction X (L1 < L2), and S1 = T1. Figure 13(a) shows the relationship between the relative position of the magnet 3 and the error θBerror when T1 = 17 mm (L1 = 11 mm), Figure 13(b) shows the relationship between the relative position of the magnet 3 and the error θBerror when T1 = 12 mm (L1 = 6 mm), and Figure 13(c) shows the relationship between the relative position of the magnet 3 and the error θBerror when T1 = 0 mm (L1 = 0 mm). In each case, T2 = 23 mm (L2 = 17 mm). Each figure also shows examples and comparative examples together. The error θBerror is calculated in the range of magnet positions -17 mm to +23 mm in Figure 13(a), in the range of magnet positions -12 mm to +23 mm in Figure 13(b), and in the range of magnet positions 0 mm to +23 mm in Figure 13(c). Examples 3-1 to 3-3 show that the linearity of the angle θB and the error θBerror are decreased compared with Example 1, but the linearity of the angle θB and the error θBerror are improved compared with the comparative examples. The present embodiment is effective when the stroke S is limited.

[0028] FIG. 14 shows a schematic diagram of the stroke sensor 1 in the reference embodiment. In the reference embodiment, as in the second embodiment, L1 < L2. However, unlike the second embodiment, S1 = S2. In other words, in the first embodiment, only the length L1 of the first soft magnetic body 4A in the first direction X is changed. FIG. 15(a) shows the relationship between T1 and the angle θB of the magnetic flux lines at the center 21 of the magnetosensitive portion of the magnetic field detection element 2. FIG. 15(b) shows the relationship between T1 and the error θBerror, and FIG. 15(c) shows the relationship between T1 and the magnetic flux density (absolute value). T1 = 0 corresponds to the case where the first soft magnetic body 4A is not present. As T1 decreases, the linearity of the angle θB and the error θBerror decrease. As T1 decreases, the magnetic flux density increases, but there is no significant difference due to T1. The reference embodiment has a smaller effect of improving the linearity of the angle θB and the error θBerror compared to the second embodiment.

[0029] (Third Embodiment) FIG. 16(a) shows a plan view of the stroke sensor 1 according to the third embodiment of the present invention. The first soft magnetic body 4A and the second soft magnetic body 4B have two surfaces 43 facing each other in the third direction Y, and the two surfaces 43 have recesses 44. The stroke sensor 1 is manufactured by insert molding. FIG. 16(b) shows the first soft magnetic body 4A and the second soft magnetic body 4B without the recess 44. A resin 45 is provided around the first soft magnetic body 4A, the second soft magnetic body 4B, and the magnetic field detection element 2. The range where the resin 45 is provided is regulated by a mold (not shown). In order to position the first soft magnetic body 4A and the second soft magnetic body 4B inside the mold, first to third jigs 46A to 46C are provided on each of the three surfaces of the first and second soft magnetic bodies 4A and 4B. FIG. 16(c) is a view similar to FIG. 16(b), showing the first soft magnetic body 4A and the second soft magnetic body 4B provided with the recess 44. First to second jigs 46A to 46B are provided in the recess 44. By making the three surfaces of the recess 44 contact the first to second jigs 46A to 46B, positioning in the X direction and the Y direction becomes possible. As a result, the third jig 46C becomes unnecessary, and the degree of freedom of the interval in the X direction between the first soft magnetic body 4A, the second soft magnetic body 4B, and the magnetic field detection element 2 increases. As shown in FIG. 16(d), a convex portion 47 can be provided instead of the recess 44. In this case, the same effect can be obtained by providing the first and second jigs 48A and 48B so as to surround the convex portion.

[0030] (Fourth Embodiment) The above-mentioned stroke sensor 1 can be used, for example, in a brake system 11. A conceptual diagram of the brake system 11 is shown in FIG. 17. The brake system 11 includes the stroke sensor 1, a brake pedal 12, and a movable member 13 that moves in a first direction X in conjunction with the brake pedal 12. The brake pedal 12 rotates counterclockwise around a first pivot 14 by an operation of the driver. Thereby, a hydraulic circuit connected to the brake pedal 12 is activated. The movable member 13 is connected to a second pivot 15 that is separated from the first pivot 14 of the brake pedal 12, and the rotational movement of the brake pedal 12 is converted into a linear movement parallel to the first direction X by a guiding mechanism (not shown). One end of a spring 16 is attached to an end of the movable member 13 on the side opposite to the second pivot 15, and the other end of the spring 16 is attached to the vehicle. Due to the biasing force of the spring 16, the brake pedal 12 is held at a predetermined position when not operated, and rotates against the biasing force of the spring 16 when operated. The above-mentioned magnet 3 is held by the movable member 13, and the above-mentioned magnetic field detection element 2 and the first and second soft magnetic bodies 4A, 4B are held by the vehicle.

Explanation of Reference Numerals

[0031] 1 Stroke sensor 2 Magnetic field detection element 3 Magnet 4A First soft magnetic body 4B Second soft magnetic body 11 Brake system 12 Brake pedal 13 Movable member 44 Recess

Claims

1. A magnetic field detection element for detecting a magnetic field, a magnet that generates a magnetic field detected by the magnetic field detection element and relatively moves in a first direction with respect to the magnetic field detection element, and a first soft magnetic material whose relative position with respect to the magnetic field detection element is fixed, wherein the stroke sensor detects a relative movement amount of the magnet in the first direction with respect to the magnetic field detection element from the direction of the magnetic field, wherein the magnetic field detection element and the first soft magnetic material are separated from the magnet in a second direction orthogonal to the first direction, wherein the first soft magnetic material is located on a side of the magnetic field detection element in the first direction as viewed from the second direction, wherein a direction orthogonal to the first and second directions is defined as a third direction, wherein a dimension of the first soft magnetic material in the first direction is L1, wherein a dimension of the first soft magnetic material in the second direction is D1, and wherein when a dimension of the first soft magnetic material in the third direction is W1, the stroke sensor satisfies L1 > D1 and L1 > W1.

2. The magnetic field detection element includes a first element that detects a magnetic flux density in the first direction and a second element that detects a magnetic flux density in the second direction, and the stroke sensor according to claim 1 further includes an arithmetic unit that calculates an angle of a combined magnetic field of the magnetic field in the first direction and the magnetic field in the second direction from the magnetic flux density in the first direction detected by the first element and the magnetic flux density in the second direction detected by the second element.

3. The stroke sensor according to claim 1 or 2, wherein the first soft magnetic material is spaced apart from the magnetic field detection element in the first direction.

4. The stroke sensor according to claim 3, wherein the first soft magnetic material is spaced apart from the magnetic field detection element by 4.1 mm or more and 7.6 mm or less.

5. The stroke sensor according to any one of claims 1 to 4, wherein 0.56 mm ≤ D1 ≤ 3 mm.

6. The stroke sensor according to any one of claims 1 to 5, wherein 2.51 mm ≤ W1 ≤ 10 mm.

7. The position of the center of the first soft magnetic material in the second direction is in a range of -3.5 mm or more and +1.0 mm or less with respect to the position of the center of the magnetically sensitive portion of the magnetic field detection element in the second direction, where the direction in which the first soft magnetic material and the magnetic field detection element move away from the magnet is defined as positive and the direction in which they approach the magnet is defined as negative. The stroke sensor according to any one of claims 1 to 6.

8. The stroke sensor according to claim 7, wherein in the second direction, the center of the magnetosensitive portion of the magnetic field detection element overlaps with the first soft magnetic body.

9. It has a second soft magnetic body whose relative position with respect to the magnetic field detection element is fixed and which is located on the opposite side of the first soft magnetic body with respect to the magnetic field detection element, Let the dimension of the second soft magnetic body in the first direction be L2, Let the dimension of the second soft magnetic body in the second direction be D2, When the dimension of the second soft magnetic body in the third direction is W2, The stroke sensor according to any one of claims 1 to 8, wherein L2 > D2 and L2 > W2.

10. The stroke sensor according to claim 9, wherein the first soft magnetic body and the second soft magnetic body are mirror-symmetrical with respect to a plane passing through the center of the magnetosensitive portion of the magnetic field detection element and parallel to the second direction and the third direction.

11. Let the maximum value of the relatively movable distance of the magnet be S, When the length of the minimum section including the first soft magnetic body and the second soft magnetic body in the first direction is T, The stroke sensor according to claim 10, wherein 0.69 ≤ T / S ≤ 1.

5.

12. The stroke sensor according to claim 11, wherein 0.89 ≤ T / S ≤ 1.

22.

13. The stroke sensor according to claim 9, wherein L1 < L2.

14. The stroke sensor according to any one of claims 1 to 13, wherein the shape of the magnet is cylindrical or columnar having a central axis parallel to the first direction.

15. The stroke sensor according to any one of claims 1 to 14, wherein the first soft magnetic body has two surfaces facing each other in the third direction, and the two surfaces have concave portions or convex portions.

16. A stroke sensor according to any one of claims 1 to 15, A brake pedal, And a movable member that moves in the first direction in conjunction with the brake pedal. A brake system in which the magnet is held by the movable member.

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