JP2004200046A - Proximity switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proximity switch in which fluctuation of magnetic flux to be impressed on the magnetic sensor is prevented regardless of assembly error, by keeping the space between the magnetic body and the bias magnet at a prescribed intereval. <P>SOLUTION: The proximity switch 1 comprises a bias magnet 2 and a magnetic sensor 3 which detects the change of impressed magnetic flux quantity from the bias magnet 2. The proximity switch 1 comprises a partition plate 6a which arranges the magnetic body 20 to be opposed at a prescribed interval from the bias magnet 2 and a regulating part 6b which positions the magnetic body 20 by contacting the partition plate 6a. The partition plate 6a has a first guide face 8a for slide-contacting the magnetic body 20, and the regulating part 6b has a second guide face 8b arranged opposed to the first guide face 8a. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a proximity switch for detecting the approach of a magnetic body.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a proximity switch including a magnet for generating a bias magnetic field (hereinafter, referred to as a bias magnet) and a magnetic sensor for detecting a magnetic flux from the magnet has been known. With this configuration, a change in the amount of magnetic flux (ie, magnetic flux density) applied to the magnetic sensor of the bias magnet when the magnetic body approaches or moves away from the proximity switch is detected, and the position of the magnetic body with respect to the proximity switch is detected. You.
[0003]
When the proximity switch having the above configuration is used, for example, as a pedal switch, the proximity switch is fixedly arranged, and the magnetic body can be moved together with the pedal. Then, the magnetic body is configured to detect the proximity switch OFF in proximity to the proximity switch when the pedal is at a rest position, and to detect the proximity switch ON when the pedal is depressed and the magnetic body operates ( For example, see Patent Document 1.) Such a proximity switch is suitably used when the switching of the switch requires certainty and speed.
[0004]
[Patent Document 1]
JP-A-9-17299 ("0008", FIG. 1)
[0005]
[Problems to be solved by the invention]
However, since the proximity switch and the member provided with the magnetic body are separate members, an assembly error between the two is likely to occur. For example, if the magnetic body approaches a position farther than an assumed predetermined position with respect to the proximity switch, the amount of magnetic flux induced by the magnetic body decreases, and conversely, the amount of magnetic flux applied to the magnetic sensor decreases. To increase. For this reason, in a proximity switch configured such that a magnetic body approaches a magnetic sensor, it is required to eliminate variations in magnetic flux applied to the magnetic sensor regardless of an assembly error.
[0006]
The present invention has been made in view of the above problems, and provides a proximity switch that prevents a variation in magnetic flux applied to a magnetic sensor by setting a predetermined interval between a magnetic body and a bias magnet regardless of an assembly error. The purpose is to do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a proximity switch including a bias magnet and a magnetic sensor that detects a change in the amount of applied magnetic flux from the bias magnet. A guide member is provided so as to be opposed to the guide member at a predetermined interval, and a regulating member is provided for positioning the magnetic body in contact with the guide member.
[0008]
According to a second aspect of the present invention, in the first aspect, the guide member has a first guide surface for slidingly contacting the magnetic body, and the regulating member is disposed opposite to the first guide surface. It has two guide surfaces.
[0009]
Furthermore, a third aspect of the present invention is characterized in that, in the first or second aspect, a guide surface for guiding the magnetic body to the guide member is provided.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the bias magnet and the magnetic sensor are provided in a case formed of a non-magnetic material. The guide member and the regulating member are formed on the case.
[0010]
Further, according to a fifth aspect of the present invention, in any one of the first to fourth aspects, a connector for connecting the case to the outside of the case and an output signal from the magnetic sensor are provided in the case. And a processing circuit for processing the signal.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a proximity switch and a pedal switch using the same will be described with reference to FIGS.
[0012]
〔Proximity switch〕
First, the proximity switch will be described.
As shown in FIGS. 1A and 1B, the proximity switch 1 has a bias magnet 2 and a magnetic sensor 3 fixed in a case 6 formed of a nonmagnetic material such as a synthetic resin. 5 and a processing circuit 4 are provided.
[0013]
In the following description, as shown in FIG. 1A, a rightward direction in the figure is called an X-axis direction, and a downward direction perpendicular to the X-axis direction is called a Y-axis direction. In addition, as shown in FIG. 1B, a downward direction in the figure, which is a longitudinal direction of the case 6, is called a Z-axis direction.
[0014]
As shown in FIG. 2, the case 6 includes a guide groove 7 formed in a columnar shape, cut off in the longitudinal direction offset from the axis, and a housing portion 9 formed in a semicircular cross section. . The guide groove 7 is open in the Y-axis direction and the opposite Y-axis direction, one end in the Z-axis direction is connected, and the other end is open. The accommodation section 9 is formed to penetrate in the Z-axis direction.
[0015]
For this reason, a partition plate 6a as a guide member is formed in the case 6 at a substantially central portion in the X-axis direction, and a regulating portion 6b as a regulating member is formed on the right side in FIG. In the inner side surface of the guide groove 7, the surface on the partition plate 6a side is a first guide surface 8a. The surface on the side of the restricting portion 6b is a second guide surface 8b which is disposed in parallel to the first guide surface 8a. Further, as shown in FIG. 1B, an inclined surface 8c as a guide surface is formed at an end of the first guide surface 8a on the open side in the Z-axis direction in the guide groove 7. Similarly, an inclined surface 8d as a guide surface is formed at an end of the second guide surface 8b on the open side in the Z-axis direction in the guide groove 7.
[0016]
The bias magnet 2 is a quadrangular prism-shaped bar magnet, and is fixed to the case 6 with its longitudinal direction being the Z-axis direction, the upper pole in the figure being an S pole and the lower pole being an N pole on the same line in the Z-axis direction. That is, the bias magnet 2 and the partition plate 6a of the case 6 are opposed to each other in parallel in the Z-axis direction. And it has a magnetic flux line (shown by a dotted line in the figure) from the N pole to the S pole. By disposing the bias magnet 2 in the housing 9 of the case 6 in this manner, the inside of the guide groove 7 is a region where the magnetic field of the bias magnet 2 is formed.
[0017]
The magnetic sensor 3 is arranged and fixed between the bias magnet 2 and the partition plate 6a. The magnetic sensor 3 detects a bias magnetic flux generated by the bias magnet 2 and outputs a signal. The magnetic sensor 3 may be provided at any position as long as it can detect the magnetic flux from the bias magnet 2. However, when the magnetic body approaches and separates from the bias magnet 2, It is preferable to be provided at a position where the amount of magnetic flux from 2 greatly changes. In the present embodiment, it is preferable to be provided at a position close to the bias magnet 2 between the bias magnet 2 and the partition plate 6a. The magnetic sensor 3 includes, for example, a Hall element, an MR element, a GMR element, and the like.
[0018]
The processing circuit 4 includes an amplification circuit that amplifies the detection signal output from the magnetic sensor 3, a comparison circuit that determines whether the amplified detection signal is equal to or less than a threshold, and outputs a determination signal. . The connector 5 connects the outside of the proximity switch 1 and outputs a determination signal determined by the processing circuit 4 to an external control circuit or the like.
[0019]
The magnetic body 20 is arranged so as to be able to approach the proximity switch 1. The magnetic body 20 is formed in a flat plate shape in the YZ plane direction, and has an area of a flat plate surface sufficiently larger than the cross-sectional area of the case 6 of the proximity switch 1 in the YZ direction. The thickness of the magnetic body 20 in the X-axis direction is substantially equal to the width of the guide groove 7 in the X-axis direction. Further, the guide groove 7 is movable in the Z-axis direction and the Y-axis direction while being restricted in the X-axis direction, and can be inserted into the guide groove 7 from the opposite Z-axis direction.
[0020]
Next, the operation of the proximity switch 1 will be described.
In the above configuration, the magnetic body 20 is inserted into the guide groove 7 of the case 6 of the proximity switch 1 so as to enter the magnetic field of the bias magnet 2 with respect to the proximity switch 1 (see FIG. 3). This state is called a proximity state. At this time, the magnetic body 20 is suitably guided into the guide groove 7 by the inclined surfaces 8c and 8d.
[0021]
Then, the magnetic body 20 induces the magnetic flux of the bias magnet 2. Therefore, the amount of magnetic flux of the bias magnet 2 detected by the magnetic sensor 3 is the amount of the magnetic flux induced by the magnetic body 20 reduced. That is, when the magnetic body 20 is separated from the proximity switch 1, a considerable amount of magnetic flux from the bias magnet 2 is applied to the magnetic sensor 3, but when the magnetic body 20 approaches the bias magnet 2, the magnetic flux is increased. Many closed loops of magnetic flux are formed in the magnetic body 20 by being absorbed by the magnetic body 20. As a result, the amount of magnetic flux applied to the magnetic sensor 3 decreases.
[0022]
At this time, the magnetic body 20 is opposed to the bias magnet 2 at a predetermined interval by the partition plate 6a of the case 6. Then, the magnetic body 20 is positioned by being brought into contact with the partition plate 6a by the regulating portion 6b. Further, the magnetic body 20 is slidably contacted with the first guide surface 8a of the partition plate 6a, and the position in the X-axis direction is restricted by the second guide surface 8b of the restricting portion 6b.
[0023]
Therefore, in the proximity state of the proximity switch 1 and the magnetic body 20, the amount of magnetic flux from the bias magnet 2 to the magnetic sensor 3 is always constant.
For example, consider the case where the proximity switch is not configured to dispose the magnetic body at a predetermined distance from the bias magnet. In this case, the gap between the bias magnet and the magnetic body is likely to fluctuate in the proximity state of the proximity switch and the magnetic body due to an assembly error between the proximity switch and the magnetic body. Then, when the gap between the magnetic body and the bias magnet is narrow, the magnetic flux is absorbed by the magnetic body and a larger number of closed loops of the magnetic flux are formed in the magnetic body as compared with the case where the gap is wide. As a result, the amount of magnetic flux applied to the magnetic sensor decreases.
[0024]
On the contrary, when the interval is large, the magnetic flux is not so much absorbed by the magnetic material, and the amount of the magnetic flux applied to the magnetic sensor does not decrease so much. As described above, when an error in assembling the proximity switch and the magnetic body occurs, the amount of magnetic flux detected by the magnetic sensor changes significantly and causes variation.
[0025]
Further, when the magnetic body 20 moves away from the proximity switch 1 in the Z-axis direction with respect to the proximity switch 1 (separated state), the magnetic flux of the bias magnet 2 is influenced by the magnetic body 20 as shown in FIG. Not receive. Therefore, in this separated state, the amount of magnetic flux from the bias magnet 2 to the magnetic sensor 3 is smaller than that when the magnetic body 20 is inserted into the guide groove 7 because the amount of magnetic flux guided to the magnetic body 20 disappears. A large amount of magnetic flux from the bias magnet 2 is applied to the magnetic sensor 3.
[0026]
4, the magnetic body 20 in the proximity state with respect to the proximity switch 1 according to the present embodiment, a change in output level when moving gradually anti Z-axis direction from the point of time T _1. 4, the horizontal axis represents time, and the vertical axis represents the output level of the proximity switch 1 (the unit is V).
[0027]
When the magnetic body 20 is in the proximity state with respect to the proximity switch 1, the output level indicates L because the amount of magnetic flux applied to the magnetic sensor 3 is reduced. Then, the time T ₁ and later, go away away the magnetic body 20 from the proximity switch 1, since the application amount of magnetic flux to the magnetic sensor 3 increases, gradually output level continue to increase, induced in the magnetic body 20 When there is no more magnetic flux, a constant output level H (> L) is obtained. As described above, the output level in the proximity state and the separation state detected by the magnetic sensor 3 absorbs an assembly error and has a constant value in the proximity state and the separation state, respectively. , It is possible to detect with high accuracy whether the magnetic body 20 is close to or not.
[0028]
[Pedal switch]
Next, a pedal switch using the proximity switch 1 having the above configuration will be described.
[0029]
In FIG. 5, a pedal switch 10 for a pedal 11 includes a proximity switch 1 fixed to a vehicle body (not shown), and a magnetic body 20 fixed to the pedal 11 supported swingably with respect to the vehicle body. I have.
[0030]
The pedal 11 is formed by connecting a rotary shaft 12 having an X-axis direction as an axis and a flat tread plate 14 having a plane extending in the XY directions by an arm 13 having a Y-axis in the longitudinal direction. . The arm 13 is bent at a position from the base end, and has an inclined portion 13a near the rotation shaft 12 and a main shaft portion 13b oriented in the Y-axis direction. As shown in FIG. 6, when the tread plate 14 is depressed, the pedal 11 is rotatable around the rotary shaft 12 to a position indicated by a dotted line in the figure. In the following description, a state in which the tread plate 14 is not depressed is referred to as a “rest state” of the pedal 11.
[0031]
The magnetic body 20 is formed to have a flat plate extending in the YZ plane direction, and is fixed to the main shaft portion 13b of the arm 13 via a connecting portion 20a. The magnetic body 20 moves in the Y-axis direction and the Z-axis direction while being restrained in the X-axis direction with the rotation of the pedal 11.
[0032]
The proximity switch 1 is fixed to the vehicle body so that the magnetic body 20 is inserted into the guide groove 7 of the proximity switch 1 when the pedal 11 is at rest.
In the above configuration, when the pedal 11 is at rest, the magnetic body 20 fixed to the pedal 11 is inserted into the guide groove 7 of the proximity switch 1. When the tread plate 14 of the pedal 11 is depressed and rotated in this state, the magnetic body 20 moves together with the arm 13 of the pedal 11, disengages from the guide groove 7 of the proximity switch 1, and separates from the proximity switch 1. At this time, the amount of magnetic flux is detected by the magnetic sensor 3, and it is detected whether or not the pedal 11 is operated.
[0033]
For example, when the pedal 11 is a brake pedal and the proximity switch 1 is used as a stop lamp that lights in conjunction with performing a brake operation in an automobile, the proximity switch 1 is connected to the brake lamp of the automobile through the connector 5. It is connected to a circuit (not shown).
[0034]
In the above configuration, when the pedal 11 is at rest, the proximity switch 1 outputs a detection signal of the output level L. The processing circuit 4 determines whether or not the detection signal is equal to or less than a threshold. When the detection signal is at the output level L, a determination signal (off signal) indicating that the detection signal is equal to or less than the threshold is output. As a result, when the off signal is input, the brake lamp driving circuit keeps a brake lamp (not shown) in a light-off state.
[0035]
On the other hand, when the tread plate 14 is depressed, the pedal 11 rotates around the rotation shaft 12 to the position shown by the dotted line in FIG. 6, and the magnetic body 20 separates from the bias magnet 2 of the proximity switch 1. In this state, the proximity switch 1 outputs a detection signal of the output level H. The processing circuit 4 determines whether or not the detection signal is equal to or less than a threshold value. If the detection signal is at an output level H, a determination signal (ON signal) indicating that the detection signal is equal to or greater than the threshold value is output. As a result, the brake lamp drive circuit turns on a brake lamp (not shown) based on the ON signal.
[0036]
Therefore, according to the proximity switch 1 of the above embodiment, the following effects can be obtained.
(1) In the present embodiment, a partition plate 6a as a guide member for arranging the magnetic body 20 to face the bias magnet 2 at a predetermined interval, and regulation for positioning the magnetic body 20 in contact with the partition plate 6a. A regulating portion 6b as a member was provided. Therefore, irrespective of an assembly error, a predetermined interval between the magnetic body 20 and the bias magnet 2, that is, a constant interval, can prevent variations in magnetic flux applied to the magnetic sensor 3.
[0037]
(2) Further, the partition plate 6a has a first guide surface 8a for slidingly contacting the magnetic body 20, and the restricting portion 6b has a second guide surface 8b arranged opposite to the first guide surface 8a. Therefore, the effect described in the above (1) can be suitably obtained.
[0038]
(3) Further, there are inclined surfaces 8c and 8d as guiding surfaces for guiding the magnetic body 20 to the partition plate 6a. Therefore, the magnetic body 20 can be guided in the guide groove 7, and the effect described in the above (1) can be suitably obtained.
[0039]
(4) The bias magnet 2 and the magnetic sensor 3 are provided in a case 6 formed of a non-magnetic material, and the partition plate 6a and the regulating portion 6b are formed in the case 6. Therefore, the effect described in the above (1) can be obtained with a simple configuration.
[0040]
(5) Further, in the case 6, a connector 5 for connecting to the outside of the case 6 and a processing circuit 4 for processing a signal output from the magnetic sensor 3 are provided. Therefore, a proximity switch having the effect described in (4) can be efficiently configured.
[0041]
Note that the above-described embodiment may be embodied by changing to another example as described below.
In the above embodiment, the connector 6 for connecting to the outside of the case 6 and the processing circuit 4 for processing a signal output from the magnetic sensor 3 are provided in the case 6. Is not limited to this configuration. For example, the connector 5 and the processing circuit 4 may be provided outside the case 6. Further, other members may be provided in the case.
[0042]
The bias magnet 2 and the magnetic sensor 3 are provided in a case 6 made of a non-magnetic material, and a partition plate 6a as a guide member and a regulating portion 6b as a regulating member are formed in the case 6. However, the guide member and the regulating member need not be formed on the case 6. For example, it may be constituted by another member. Further, if the guide member is a guide member which can arrange the magnetic body at a predetermined interval with respect to the bias magnet and a regulating member which positions the magnetic body by contacting the guide member, how is the guide member and the regulating member? You may comprise.
[0043]
-Furthermore, although the inclined surfaces 8c and 8d are provided as the guiding surfaces, they may not be provided.
The partition plate 6a has a first guide surface 8a for slidingly contacting the magnetic body 20, and the restricting portion 6b has a second guide surface 8b opposed to the first guide surface 8a. The first and second guide surfaces 8a, 8b need not be planar.
[0044]
For example, as shown in FIG. 7, bar members 31 are arranged as guide members at predetermined intervals with respect to the bias magnet 2, and further, a bar member 32 is provided as a regulating member that is brought into contact with and positioned with the bar member 31. They may be arranged in a line. Alternatively, as shown in FIG. 8, the first guide surface 41 and the second guide surface 42, on each of which the protrusions are arranged in a row, may be used to guide the magnetic body 20 by contacting the tops of the protrusions.
[0045]
【The invention's effect】
As described in detail above, according to the first to fifth aspects of the present invention, regardless of an assembly error, a predetermined interval is set between the magnetic body and the bias magnet, and Variation can be prevented.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view of a proximity switch according to an embodiment of the present invention in a cross-sectional direction, and FIG.
FIG. 2 is a perspective view of the same case.
FIG. 3 is a cross-sectional view illustrating the operation.
FIG. 4 is a graph showing a change in magnetic field intensity.
FIG. 5 is a front view schematically illustrating the pedal switch of the embodiment.
FIG. 6 is a side view of the same.
FIG. 7 is a cross-sectional view schematically illustrating another example.
FIG. 8 is a cross-sectional view schematically illustrating another example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Proximity switch 2 ... Bias magnet 3 ... Magnetic sensor 6a ... Partition plate (guide member)
6b: regulation part (regulation member)
8a: first guide surface 8b: second guide surface 20: magnetic material

Claims (5)

In a proximity switch including a bias magnet and a magnetic sensor that detects a change in the amount of applied magnetic flux from the bias magnet,
A proximity switch, comprising: a guide member for arranging a magnetic body facing a bias magnet at a predetermined interval; and a regulating member for positioning the magnetic body in contact with the guide member. The said guide member has the 1st guide surface which makes the said magnetic body slidably contact, and the said regulating member has the 2nd guide surface arrange | positioned facing the said 1st guide surface, The claim of Claim 1 characterized by the above-mentioned. Proximity switch. The proximity switch according to claim 1, further comprising a guide surface that guides the magnetic body to the guide member. 4. The bias magnet and the magnetic sensor are provided in a case formed of a non-magnetic material, and the guide member and the regulating member are formed in the case. The proximity switch according to claim 1. 5. The proximity switch according to claim 4, wherein a connector for connecting to the outside of the case and a processing circuit for processing a signal output from the magnetic sensor are provided in the case. .

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