JP2007012376A - Proximity switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proximity switch wherein output variation of a magnetic sensor is steep regardless of the moving speed of a mobile body used as a movement detection object and which can thereby stably execute on/off changeover. <P>SOLUTION: A slider 52 having further entered into a casing 12 presses a movable part 26 at its one end. However, the movable part 26 is energized toward a plate part 22 by energizing force of a return spring 38 resisting its spring force. Thereby, even if pressing force from the slider 52 is given to the movable part 26, the movable part 26 can not move to the plate 18 side and bent. When the spring force of the movable part 26 increased by the bending and the pressing force from the slider 52 exceed the energizing force of the return spring 38, the movable part 26 tends to rapidly restore (stretch) its shape. Thereby, the tip side of the movable part 26 rapidly moves toward the plate part 18 and a permanent magnet 30 rapidly approaches the magnetic sensor 32. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a proximity switch using a magnetic sensor such as a Hall element or a magnetoresistive element and a permanent magnet.

  For example, a detection device for detecting whether or not a brake pedal of a vehicle has been depressed, and a detection device for detecting whether or not a tongue plate is attached to a buckle device that constitutes a seat belt device include magnetic A proximity switch to which a sensor is applied (see Patent Document 1 below as an example) may be used.

  This type of proximity switch includes a magnetic sensor such as a Hall element or a magnetoresistive element, and a permanent magnet. The permanent magnet is attached to the movable part of the device. When the movable part is moved by a depressed brake pedal or a tongue plate inserted in the buckle device, the permanent magnet is moved together with the movable part.

The permanent magnet forms a constant magnetic field around the permanent magnet. However, when the permanent magnet moves together with the movable part, the magnetism detected by the magnetic sensor fluctuates. Since the output of the magnetic sensor changes according to the detected magnetism, when the detected magnetism fluctuates, the output from the magnetic sensor also changes.When the output of the magnetic sensor exceeds a certain threshold, the proximity switch On and off.
Japanese Patent Laid-Open No. 2003-197078

  By the way, the permanent magnet forms a magnetic field having a relatively gentle magnetic flux gradient in the vicinity thereof. For this reason, the fluctuation | variation of the magnetism which a magnetic sensor detects when a permanent magnet moves after approaching a magnetic sensor to the vicinity of a permanent magnet becomes very gentle.

  Moreover, the output of a magnetic sensor often changes depending on the temperature, and in order to mount a proximity switch using such a magnetic sensor on a vehicle, the output of the magnetic sensor must be set on the condition that the output exceeds the threshold value. It is difficult to make a configuration that switches between on and off.

  In view of the above facts, the present invention has an object to obtain a proximity switch that can be switched on and off stably with a steep change in output of a magnetic sensor regardless of the moving speed of a moving object that is a target of movement detection. It is.

  According to a first aspect of the present invention, the proximity switch according to the present invention detects a permanent magnet that forms a predetermined magnetic field in the surroundings, the magnetism of the magnetic field formed by the permanent magnet, and according to the detected change in the magnetism. The magnetic detection means whose output changes, and is supported rotatably at a predetermined position, and either the permanent magnet or the magnetic detection means is attached at a position away from the rotation center and is rotated. A holding member having a spring property for moving either one of the permanent magnet and the magnetic detection means toward or away from the other, and a direction in which the one approaches or separates from the other A regulating means for regulating the movement by interfering with the holding member from the direction side, and for releasing the regulation when a spring force generated in the holding portion exceeds a certain level due to the regulation; The said regulating means via a member slidable toward the side of the holding member on the opposite side is provided with a pressing member that presses the holding means by sliding, the.

  According to the proximity switch of the first aspect, when the pressing member is slid to press the holding member, the pressing member tends to rotate. When the pressing member rotates, one of the permanent magnet and the magnetic detection means approaches or separates from the other. However, when the holding member pressed by the pressing member tries to rotate, the holding member is interfered by the restricting means and the rotation is restricted. Even if the pressing member is further slid in this state to press the holding member, if the pressing force does not exceed a certain magnitude, the interference of the holding member by the regulating means is not eliminated, and the holding member is Elastically deforms.

  If the sliding amount of the pressing member exceeds a certain stroke, the pressing force applied to the holding member exceeds a certain amount, and the spring force of the retaining member caused by elastic deformation exceeds a certain amount, the regulation The restriction of the holding member by the means is eliminated, and the holding member is a restoring force based on the spring force, and suddenly rotates in a direction in which one of the permanent magnet and the magnetic detection means approaches or separates from the other.

  Thus, until the spring force generated by the elastic deformation of the holding member reaches a certain magnitude, the permanent magnet cannot relatively approach or separate from the magnetic detection means, and the spring force of the holding member is constant. After reaching the size, the permanent magnet relatively abruptly approaches or separates from the magnetic detection means by the restoring force of the holding member. For this reason, the magnetism of the permanent magnet detected by the magnetic detection means changes rapidly, and the output of the magnetic detection means changes rapidly.

  As described above, in the proximity switch according to the present invention, the output change of the magnetic sensor is steep and stable on / off switching regardless of the moving speed of the moving object to be detected.

<Configuration of the present embodiment>
FIG. 1 is a perspective view showing the configuration of a proximity switch 10 according to an embodiment of the present invention.

  As shown in this figure, the proximity switch 10 includes a housing 12. The housing 12 includes a base 14 and a cover 16. The base 14 includes a flat plate portion 18. A peripheral wall 20 is erected on the outer peripheral portion of the plate portion 18, and the base 14 is formed in a box shape that opens toward one side in the thickness direction of the plate portion 18 as a whole.

  On the other hand, the cover 16 includes a plate-like plate portion 22 parallel to the plate portion 18. A peripheral wall 24 is erected on the outer peripheral portion of the plate portion 22, and the cover 16 is formed in a box shape that opens in the direction opposite to the opening direction of the base 14 as a whole.

  Further, the plate portion 22 is thinner than the intermediate portion of the peripheral wall 24 along the thickness direction of the plate portion 22 on the side opposite to the plate portion 22 than the plate portion 22 side. Fit from the outside. Thereby, the opening side of the base 14 is closed.

  A movable portion 26 that constitutes a holding unit is provided inside the housing 12 having the above configuration. The movable portion 26 is generally a plate spring having a rectangular shape in plan view, and the movable portion 26 can be elastically deformed so as to be bent around an axis whose axial direction is the width direction.

  The movable portion 26 has a thickness direction substantially along the thickness direction of the plate portion 18 on the base end side in the longitudinal direction, and the longitudinal base end portion of the movable portion 26 is supported by a support piece 28 provided on the plate portion 18. It is fixed. Therefore, the movable portion 26 has a structure that can be elastically deformed so that the front end side in the longitudinal direction rotates with the width direction as an axial direction.

  A permanent magnet 30 is provided on the other end side in the longitudinal direction of the movable portion 26. The permanent magnet 30 is fixed to the surface of the movable portion 26 on the plate portion 18 side in the thickness direction. Corresponding to the permanent magnet 30 fixed to the movable part 26, a magnetic sensor 32 as a magnetic detection means is attached on the plate part 18.

  The magnetic sensor 32 is configured by a Hall element, a magnetoresistive element (including a giant magnetoresistive element), or the like. A support piece 34 is provided on the plate portion 18 on the proximal side in the longitudinal direction of the movable portion 26 with respect to the magnetic sensor 32.

  The support piece 34 can interfere with a part of the movable portion 26 on the plate portion 18 side when the elastically deformable movable portion 26 is rotated by its restoring force (spring force). In the state of interference with the plate portion 18, a slight gap is formed between the permanent magnet 30 and the magnetic sensor 32 along the thickness direction of the plate portion 18. This prevents contact between the permanent magnet 30 and the magnetic sensor 32, in particular, collision of the permanent magnet 30 with the magnetic sensor 32 due to the spring force of the movable portion 26.

  In addition, a buffer portion 36 is provided in the plate portion 22 corresponding to the distal end side of the movable portion 26. The buffer portion 36 is formed of, for example, block-shaped rubber, and the movable portion 26 rotates around the longitudinal base end portion, and the plate around the axis whose axial direction is the width direction of the movable portion 26. When the movable portion 26 is curved so as to open toward the portion 22 side, the buffer portion 36 abuts on the distal end side in the longitudinal direction of the movable portion 26.

  On the other hand, the movable portion 26 is provided with a return spring 38 as a restricting means. The return spring 38 is a plate spring having a substantially rectangular shape in plan view like the movable portion 26, and the longitudinal direction and the width direction thereof are substantially along the longitudinal direction and the width direction of the movable portion 26. A rectangular through hole 40 is formed in the longitudinal direction intermediate portion of the movable portion 26 corresponding to the return spring 38.

  The through hole 40 corresponds to the shape of the return spring 38, and the distal end portion of the return spring 38 is connected to the movable portion 26 at a portion of the inner peripheral portion of the through hole 40 on the distal end side of the movable portion 26. Furthermore, the return spring 38 is a remaining portion when the through hole 40 is formed in the movable portion 26 while leaving a continuous portion with the movable portion 26.

  On the other hand, a support piece 42 is erected between the support piece 28 and the support piece 34 on the plate portion 18. A substantially triangular holding groove 44 is formed on the surface of the support piece 42 on the support piece 34 side in a side view.

  The linear distance from the bottom of the holding groove 44 to the continuous portion of the return spring 38 with the movable portion 26 is sufficiently shorter than the longitudinal dimension of the return spring 38 so that the support piece 42 on the plate portion 18 has a length. The standing position and the formation position of the holding groove 44 are set.

  A base end portion of the return spring 38 (an end portion on the side opposite to the continuous portion with the movable portion 26 along the longitudinal direction) enters the holding groove 44. Since the linear distance from the bottom of the holding groove 44 to the continuous portion of the return spring 38 with the movable portion 26 is sufficiently shorter than the longitudinal dimension of the return spring 38 as described above, the return spring 38 is on the plate portion 22 side. Curved to open toward

  Since the restoring shape of the return spring 38 is a flat plate shape, a spring force (restoring force) is generated so as to restore the original flat plate shape by bending, and this spring force biases the movable portion 26 toward the plate portion 22 side. is doing.

  As described above, when the movable portion 26 rotates around the base end portion in the longitudinal direction or is curved so as to open toward the plate portion 22 around an axis having the width direction of the movable portion 26 as an axial direction, the movable portion 26 is movable. The distal end side of the portion 26 abuts against the buffer portion 36, but the spring force (biasing force) of the return spring 38 is larger than the spring force (biasing force) generated in the movable portion 26 in a state where the distal end side of the movable portion 26 is in contact with the buffer portion 36 in this way. The shape of the return spring 38, the position of the support piece 42, and the like are set so that the urging force is greater. For this reason, in a state where an external force other than the spring force of the return spring 38 is not acting on the movable portion 26, the distal end side of the movable portion 26 is in pressure contact with the buffer portion 36.

  A retraction hole 46 is formed in the plate portion 18 corresponding to the return spring 38, and the return spring 38 bends until it comes into contact with the upper surface of the plate portion 18 (the surface on the side facing the plate portion 22). In this case, the return spring 38 enters the retraction hole 46. Accordingly, unnecessary interference from the plate portion 18 when the return spring 38 is elastically deformed can be prevented.

  On the other hand, a guide hole 48 penetrating in the thickness direction is formed in the plate portion 22 so as to correspond between the support piece 28 and the support piece 42 of the plate portion 18. A guide tube 50 is formed in the plate portion 22 corresponding to the guide hole 48, and the inner peripheral portion of the guide hole 48 and the inner peripheral portion of the guide tube 50 are continuous in the thickness direction of the plate portion 22.

  A slider 52 as a pressing member is inserted into the guide hole 48 and the guide tube 50. The cross-sectional shape of the slider 52 is the same as the opening shape of the guide hole 48 and the guide tube 50, and the slider 52 can slide in the opening direction of the guide hole 48 and the guide tube 50.

  One end of the slider 52 is in contact with the movable portion 26 between the support piece 28 and the support piece 42. Further, the slider 52 passes through the guide hole 48 and the guide tube 50 while one end of the slider 52 is in contact with the movable portion 26 in a state where the movable portion 26 is moved or deformed (restored) until the movable portion 26 contacts the support piece 34. The dimension of the slider 52 (the dimension along the opening direction of the guide hole 48 and the guide cylinder 50) is set to such an extent that it projects to the outside of the housing 12.

  Further, a slider 54 is attached to the back surface (upper surface) of the plate portion 22 so as to be slidable in a predetermined direction (the left-right direction in FIGS. 2 to 4) along the back surface of the plate portion 22. A hole 58 having a slope 56 is formed in the slider 54. The inclined surface 56 of the hole 58 is inclined toward the opening side of the hole 58 with respect to the direction toward the guide hole 48 along the sliding direction of the slider 54.

  When the slider 54 slides in one sliding direction (the right direction in FIGS. 2 to 4), the inclined surface 56 contacts the other end of the slider 52. Further, in this state, when the slider 54 is slid in one of the sliding directions, the inclined surface 56 pushes the slider 52 into the housing 12.

<Operation and effect of the present embodiment>
Next, the operation and effect of the proximity switch 10 will be described.

  In the proximity switch 10, when the slider 54 is slid in one sliding direction (right direction in FIG. 2) in the initial state of the slider 54 shown in FIG. To touch. When the slider 54 is further slid in one of the sliding directions in this state, the inclined surface 56 presses the slider 52.

  With this pressing force, the slider 52 further enters the inside of the housing 12 while being guided by the guide hole 48 and the guide tube 50. When the slider 52 enters the inside of the housing 12 in this way, one end of the slider 52 presses the movable portion 26.

  On the other hand, as described above, the movable portion 26 is urged toward the plate portion 22 by the urging force against the return spring 38 that resists the spring force. Therefore, even if the pressing force from the slider 52 is applied to the movable portion 26, the movable portion 26 can be moved to the plate unless the resultant force of the spring force of the movable portion 26 and the pressing force from the slider 52 exceeds the urging force of the return spring 38. It cannot move to the part 18 side.

  Therefore, in such a state, as shown in FIG. 3, the movable portion 26 does not move toward the plate portion 18, but receives the pressing force from the slider 52 so that the width direction becomes the axial direction. It is curved in a concave shape that opens around the axis toward the plate portion 22 side. Thus, the spring force of the movable part 26 increases because the movable part 26 curves.

  As described above, when the slider 54 is slid in one of the sliding directions and the inclined surface 56 pushes the slider 52 into the housing 12, the movable portion 26 is further curved. When the resultant force of the spring force of the movable portion 26 and the pressing force from the slider 52 increased by bending in this way exceeds the urging force of the return spring 38, as shown in FIG. Attempts to restore (extend) its shape.

  As a result, the movable portion 26 is supported by the support piece 34 with its distal end abruptly moved to the plate portion 18 side.

  Next, when the slider 54 is slid in the other sliding direction from the state shown in FIG. 4, the pressing force from the inclined surface 56 of the slider 52 gradually decreases. For this reason, the pressing force applied to the movable portion 26 is also reduced, and the movable portion 26 is gradually pressed against one end of the slider 52 by the urging force of the return spring 38 that can resist the spring force of the movable portion 26. Move to the side.

  That is, in the proximity switch 10, the movable portion 26 moves differently when the slider 54 is slid in one sliding direction and when the slider 54 is slid in the other sliding direction.

  Here, as shown in FIG. 5, in the proximity switch 10, the slider 52 presses the movable portion 26 until the slider 54 slides a certain amount, but the permanent magnet 30 provided in the movable portion 26. Does not approach the magnetic sensor 32.

  Next, when the sliding amount of the slider 54 exceeds a certain stroke (R1 in FIG. 5), as described above, the resultant force of the spring force of the movable portion 26 and the pressing force applied to the movable portion 26 by the slider 52 is the return spring. The urging force of 38 is exceeded, and the movable part 26 suddenly moves closer to the plate part 18 side.

  For this reason, as shown between R1 and R2 in FIG. 5, the permanent magnet 30 provided in the movable portion 26 suddenly approaches the magnetic sensor 32. Further, when the permanent magnet 30 suddenly approaches the magnetic sensor 32 in this way, the output voltage from the magnetic sensor 32 quickly reaches E1 to E2, as shown between R1 and R2 in FIG.

  In this way, when the output voltage from the magnetic sensor 32 suddenly increases and reaches E2 from E1, it exceeds the preset Es as the threshold value, so that the electric circuit connected to the magnetic sensor 32 is turned on. It is switched off.

  Incidentally, the output voltage of the magnetic sensor 32 increases (a two-dot chain line state in FIG. 6) or decreases (a dotted line state in FIG. 6) due to a change in the ambient temperature or the like. However, in the proximity switch 10, as described above, the distal end side of the movable portion 26 moves abruptly, and the permanent magnet 30 suddenly approaches the magnetic sensor 32, whereby the output voltage at the magnetic sensor 32 is reduced. It changes rapidly.

  As described above, even if the ambient temperature changes and the output voltage at the magnetic sensor 32 increases or decreases, the output voltage at the magnetic sensor 32 suddenly increases as the permanent magnet 30 approaches the magnetic sensor 32 rapidly. There is no change in changing to. For this reason, as shown in FIG. 6, even if the ambient temperature or the like changes, the output voltage at the magnetic sensor 32 falls within the threshold Es in the very short slide range dR within the slide range of the slider 52. Over.

  As a result, the output voltage of the magnetic sensor 32 can surely exceed the threshold value Es within the sliding range of the slider 52 even if it is considered in advance that the ambient temperature changes, and the slider 54 is operated. Thus, at least the electrical circuit to which the magnetic sensor 32 is connected can be surely switched from one of on and off to the other.

It is a disassembled perspective view which shows the structure of the proximity switch which concerns on one embodiment of this invention. It is sectional drawing which shows the initial state of the proximity switch which concerns on one embodiment of this invention. It is sectional drawing corresponding to FIG. 2 which shows the state which the holding means elastically deformed by the pressing force from a pressing member. It is sectional drawing corresponding to FIG. 2 which shows the state in which the permanent magnet approached the magnetic sensor. It is a graph which shows the relationship between the sliding amount of a slider, and the distance from a permanent magnet to a magnetic sensor. It is a graph which shows the relationship between the sliding amount of a slider, and the output from a magnetic sensor.

Explanation of symbols

10 Proximity switch 26 Movable part (holding means)
30 Permanent magnet 32 Magnetic sensor (Magnetic detection means)
38 Return spring (regulator)
52 Slider (Pressing member)

Claims (1)

A permanent magnet that forms a predetermined magnetic field around it;
Magnetic detection means for detecting the magnetism of the magnetic field formed by the permanent magnet, and for changing the output in accordance with the detected change in the magnetism;
The permanent magnet and the magnetic detection means are supported at a predetermined position so as to be rotatable, and one of the permanent magnet and the magnetic detection means is attached to a position away from the rotation center. A holding member having a spring property for moving either one of the above and the other with respect to any other;
The movement of the holding member is restricted by interference with the holding member from the side in which the one approaches or separates from the other, and the spring force generated in the holding portion by the restriction is constant. A regulation means for releasing the regulation when exceeding the limit,
A pressing member that is slidable toward the side of the holding member on the opposite side of the restricting means via the holding member, and presses the holding means by sliding;
Proximity switch with.

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