JP7126087B2 - stroke sensor - Google Patents

Description

The present invention relates to stroke sensors.

BACKGROUND ART Patent Document 1, for example, discloses a stroke sensor that detects the amount of movement of a moving object such as a lever of an automobile or a motorcycle.
The stroke sensor includes a detection shaft that follows the movement of the object to be detected, a housing that restricts the rotation of the detection shaft and slidably supports it, and a sensor that is provided between the detection shaft and the housing to detect the amount of movement. and an origin return mechanism for returning the detection shaft after it has been moved to the origin position. is detected by changes in the magnetic field.

JP 2017-015549 A

However, since the stroke sensor described in Patent Document 1 includes an origin return mechanism using two pistons to limit the amount of movement of the detection shaft, there is a problem that the structure becomes complicated and the number of parts increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stroke sensor with a simplified structure and reduced cost.

In order to achieve the above object, a stroke sensor according to the present invention comprises:
A stroke sensor that detects the amount of movement of a detection shaft that follows an object to be detected and moves from an origin position,
the sensing shaft having an enlarged diameter portion, a first washer and a second washer;
a first housing supporting the detection shaft;
a second housing supporting the sensing shaft;
a spring that returns the detection shaft to the origin position after moving from the origin position;
a magnet for changing the magnetic field as the detection shaft moves;
a magnetic detection element that detects the amount of movement of the detection shaft from changes in the magnetic field accompanying the movement of the detection shaft;
with
The first housing has a first receiving portion that receives the large diameter portion,
the second housing has a second receiving portion for receiving the first washer;
the first washer and the second washer are in contact with the spring;
the first receiving portion and the second receiving portion limit the amount of movement of the detection shaft;
It is characterized by

ADVANTAGE OF THE INVENTION According to this invention, the stroke sensor which simplified the structure and reduced the cost can be provided.

It is a top view showing an example of a stroke sensor of the present invention. 1 is a cross-sectional view taken along line AA showing an embodiment of a stroke sensor of the present invention; FIG. FIG. 4 is a cross-sectional view taken along line AA showing the detection shaft, first housing, and second housing of the embodiment of the stroke sensor of the present invention;

A stroke sensor according to the present invention will be described below with reference to the accompanying drawings.

Please refer to FIG. 1 and FIG. FIG. 1 shows a plan view of an embodiment of a stroke sensor 1. FIG. FIG. 2 shows a cross-sectional view of an embodiment of the stroke sensor 1. FIG. The stroke sensor 1 is a stroke sensor that detects a movement amount S of a detection shaft 10 that moves from an origin position O following an object to be detected. a first housing 20 having a first receiving portion 21; a second housing 30 having a second receiving portion 31; A spring 40 for returning to the position O, a magnet 51 for changing the magnetic field with the movement of the detection shaft 10, and a magnetism detector for detecting the movement amount S of the detection shaft 10 from the change in the magnetic field with the movement of the detection shaft 10. an element 52;

Also refer to FIG. FIG. 3(a) shows a sectional view of the detection shaft 10 of the embodiment of the stroke sensor 1. FIG. The detection shaft 10 is a detection medium that is followed by the movement of the object to be detected. For example, the detection shaft 10 is connected to the object to be detected, receives external force, and reciprocates in the axial direction to follow. The detection shaft 10 is preferably made of a nonmagnetic material having a certain degree of rigidity, such as austenitic stainless steel (Steel Use Stainless; SUS).

The detection shaft 10 has a cylindrical large-diameter portion 11, a medium-diameter portion 12, and a small-diameter portion 13 having different diameters. , medium diameter portion 12b, and small diameter portion 13 are arranged.

The enlarged diameter portion 11 is disposed within the first housing 20 and supports the first washer 18a.

The mid-diameter portion 12a is disposed in the first housing 20, and has a notched surface 16 formed by flatly cutting the side surface of the detection shaft 10 and an end surface 17 having a substantially D-shaped cross section. Further, the middle diameter portion 12a has a magnet storage portion 19 that stores the magnet 51 therein.

The middle diameter portion 12b has a first washer 18a, a spring 40, and a second washer 18b passed through the large diameter portion 11 side, and a retaining ring 14 and an airtight member 15 attached to the small diameter portion 13 side.

The small-diameter portion 13 protrudes outward from the shaft hole 33 of the second housing 30 and is connected to an object to be detected (not shown).

The snap ring 14 is a radially mounted snap ring made of a non-magnetic material, and is held by a groove (not shown) provided in the central portion 12b. The retaining ring 14 supports the second washer 18b.

The airtight member 15 is an O-ring made of rubber and held by a groove provided in the middle diameter portion 12b. The airtight member 15 is used to keep the stroke sensor 1 airtight, and the groove is configured to satisfy the groove structure necessary for the airtight function of the airtight member 15 to be exhibited.

The notch surface 16 is a flat surface formed by notching the side surface of the detection shaft 10 and has a shorter axial length than the shaft support portion 22 of the first housing 20 . Rotation of the detection shaft 10 is restricted by the cutout surface 16 in cooperation with a flat portion 22a of the shaft support portion 22, which will be described later.

The end surface 17 is a cross section formed by a notch in the side surface of the detection shaft 10 and has a substantially D shape. The height from the notch surface 16 to the vertex of the end surface 17 substantially matches the height of the recessed portion 25 which will be described later.

The first washer 18a is an O-shaped washer made of a non-magnetic material, and has a diameter larger than that of the large-diameter portion 11, the inner diameter of the second housing 30, and the spring 40. It is configured to be smaller than the inner diameter of the cylindrical portion 20a.
The second washer 18b is an O-shaped washer made of a non-magnetic material, and has a diameter larger than that of the hole 32 and the spring 40 of the second housing 30, which will be described later, and smaller than the inner diameter of the second housing 30. Configured.
The first washer 18a and the second washer 18b are designed to withstand a thrust load when the sensing shaft 10 moves and contacts another member.

The magnet housing portion 19 is formed by hollowing out the inside of the detection shaft 10, for example, and houses the magnet 51 and holds it by fixing it with an adhesive or the like.

Also refer to FIG. FIG. 3(b) shows a cross-sectional view of the first housing 20 of the embodiment of the stroke sensor 1. FIG. The first housing 20 includes a first receiving portion 21 for receiving the large diameter portion 11 of the detection shaft 10, a shaft support portion 22, a first washer support portion 23, a mounting portion 24, a recess 25, and a female screw. It is configured to have a portion 29 .

The first housing 20 is preferably made of a nonmagnetic material such as aluminum or stainless steel, and is formed of a substantially cylindrical portion 20a and a flat plate portion 20b.

The first receiving portion 21 is an annular surface provided inside the cylindrical portion 20 a , contacts the large diameter portion 11 of the detection shaft 10 , and limits the amount of movement S of the detection shaft 10 . The length from the origin position O to the first receiving portion 21 is configured to be smaller than the maximum amount of deflection of the spring 40 .

The shaft support portion 22 is provided inside the flat plate portion 20 b and is formed as a groove that supports the middle diameter portion 12 a of the detection shaft 10 . The shaft support portion 22 has a flat portion 22 a that faces the cutout surface 16 of the detection shaft 10 . The planar portion 22a and the notched surface 16 of the detection shaft 10 restrict the rotation about the center axis, and support the detection shaft 10 so that the detection stroke S can slide with high accuracy in the axial direction.

The first washer support portion 23 is an annular surface provided inside the cylindrical portion 20a, and has a diameter larger than that of the large diameter portion 11 of the detection shaft 10 and smaller than that of the first washer 18a.

The mounting portion 24 is provided outside the flat plate portion 20b, and is provided with a screw hole for mounting a third housing 60, which will be described later.

The concave portion 25 is formed by digging the surface of the mounting portion 24 and is used to dispose a magnetic detecting element 52 to be described later close to the detecting shaft 10 . The housing is displaced inwardly by the height of the concave portion 25 that is dug down, and the flat portion 22a is formed on the shaft support portion 22 . The height of the concave portion 25 dug down substantially matches the height from the cutout surface 16 of the detection shaft 10 to the top of the end surface 17 .
The thickness of the housing of the concave portion 25 is the height from the flat portion 22a to the concave portion 25. As shown in FIG. It is preferable that the thickness of the housing of the concave portion 25 substantially matches the thickness of the housing on the opposite side of the detection shaft 10, that is, the thickness of the housing on the line symmetrical position about the detection shaft 10 as an axis.

A female threaded portion 29 is provided on the inner diameter surface of the cylindrical portion 20 a and is used to connect the first housing 20 and the second housing 30 .

Also refer to FIG. FIG. 3(c) shows a cross-sectional view of the second housing 30 of the stroke sensor 1 embodiment. The second housing 30 includes a second receiving portion 31 for receiving the first washer 18a of the detection shaft 10, a hole portion 32, a shaft hole 33, a second washer support portion 34, a chamfer portion 35, It is configured with a male screw portion 39 .

The second housing 30 is preferably made of a non-magnetic material such as aluminum or stainless steel, and has a substantially cylindrical shape.

The second receiving portion 31 is an annular surface provided on the edge of the second housing 30 , receives the first washer 18 a of the detection shaft 10 , and limits the amount of movement S of the detection shaft 10 . The length from the origin position O to the second receiving portion 31 is configured to be smaller than the maximum amount of deflection of the spring 40 .

The hole portion 32 is provided inside the second housing 30 in the opposite direction to the second receiving portion 31, and has a diameter larger than that of the retaining ring 14 and smaller than that of the second washer 18b. The depth of the hole portion 32 is set slightly longer than the amount of movement S so that the retaining ring 14 does not come into contact with the second housing 30 in the thrust direction.

The shaft hole 33 is provided in the hole portion 32 to slidably support the detection shaft 10 and take it out to the outside.

The second washer support portion 34 is an annular surface provided on the outer circumference of the hole portion 32, and has a diameter larger than that of the hole portion 32 and smaller than that of the second washer 18b.

The chamfered portion 35 is provided in the direction of the hole portion 32 of the shaft hole 33 and grinds the corner portion of the shaft hole 33 to make it smooth. The chamfered portion 35 prevents the airtight member 15 from being damaged by the corner portion of the shaft hole 33 when the detection shaft 10 is passed through the shaft hole 33 from the direction of the hole portion 32 . The chamfered portion 35 is located in the direction of the large diameter portion 11 of the detection shaft 10 after the detection shaft 10 is passed through the shaft hole 33 .

A male threaded portion 39 is provided on the outer diameter surface of the second housing 30 in the direction opposite to the hole portion 32 and is used to connect the first housing 20 and the second housing 30 . At the time of connection, loosening of the screw may be further prevented by using a reinforcing adhesive (for example, a sealock agent) or the like.

The spring 40 is preferably made of a nonmagnetic material such as stainless steel, and is composed of, for example, a cylindrical coil spring made of SUS304WPB.

The spring 40 is configured to pass the detection shaft 10 inside and contacts the first washer 18a and the second washer 18b of the detection shaft 10 .

When the spring 40 moves so that the detection shaft 10 at the origin position O is pushed toward the first housing 20, the second washer 18b supported by the retaining ring 14 pushes the spring 40, The spring 40 is crushed by the first washer 18a supported by the washer support portion 23 of the first housing 20. It can move by the amount of movement S until it hits 21 . Then, when the force pushing the detection shaft 10 is removed, the spring force accumulated in the spring 40 returns the detection shaft 10 to the origin position O.

Further, when the spring 40 moves so that the detection shaft 10 at the origin position O is pulled toward the second housing 30, the first washer 18a supported by the large diameter portion 11 pushes the spring 40, and , the second washer 18b supported by the second washer support portion 34 supports the spring 40, the spring 40 is crushed, and the first washer 18a supported by the large-diameter portion 11 of the detection shaft 10 can move by a movement amount S until it hits the second receiving portion 31 of the second housing 30 . Then, when the force with which the detection shaft 10 is pulled in disappears, the spring force accumulated in the spring 40 returns the detection shaft 10 to the origin position O.

The magnet 51 is a columnar rare-earth magnet (for example, a magnet made of a material such as SmCo or NdFeB), and is attached to the magnet housing portion 19 of the detection shaft 10 .

The magnet 51 provides a magnetic field to the magnetic detection element 52 , and as the magnet 51 moves with the detection shaft 10 , the direction and strength of the magnetic field applied to the magnetic detection element 52 are changed. is detected as the movement amount S. The magnet 51 may be a sintered magnet or a plastic magnet mixed with plastic and compressed or molded depending on the manufacturing method. While sintered magnets have stronger magnetic force, plastic magnets have characteristics such as higher mass productivity and crack resistance.

The magnetic detection element 52 detects changes such as the amount of movement of the object to be detected based on the direction and strength of the magnetic field. is converted into an electrical signal and output to the outside.

The movement amount S of the detection shaft 10 is detected by the magnetic detection element 52 by detecting changes in the direction and strength of the magnetic field generated by the magnet 51 provided on the detection shaft 10, and converting it into an electric signal corresponding to the magnetic field. output to the outside.

The substrate 50 is a printed circuit board (PCB) made of glass epoxy or the like, and includes a magnetic detection element 52 .

Power supply to the magnetic detection element 52 of the substrate 50 and electric signal output to the outside are performed by a direct connector or a cord.

The third housing 60 is made of a resin material such as epoxy resin, and is coupled with the mounting portion 24 of the first housing 20 by screws.

The third housing 60 has a board storage portion 61 and a drawer port 62 .

The substrate housing portion 61 is configured to hold the substrate 50 in the third housing 60 and place the magnetic sensing element 52 close to the recess 25 of the first housing 20 .

The lead-out port 62 leads out the direct connector or cord of the board 50 to the outside.

The present invention described above has the following effects.

By receiving the large-diameter portion 11 in the first receiving portion 21 of the first housing 20 and the first washer 18a in the second receiving portion 31 of the second housing 30, the detection shaft can be detected without adding members. 10 can be limited. This simplifies the assembly process and reduces material costs.

By limiting the amount of movement S of the detection shaft 10, the amount by which the spring 40 is crushed is reduced. According to this, the load on the spring 40 can be reduced and the life of the spring 40 can be extended.

By using the first washer 18a having a larger diameter than the large diameter portion 11 of the detection shaft 10, the diameter of the large diameter portion 11 can be reduced. According to this, the diameter of the detection shaft material before cutting can be made small, and material cost and processing cost can be reduced.

By providing the chamfered portion 35 in the shaft hole 33 of the second housing 30 , it is possible to prevent the airtight member 15 from being damaged by the corners of the shaft hole 33 during assembly of the stroke sensor 1 . According to this, the assembly accuracy can be improved and the defective product rate can be reduced.

In the above embodiment, the first housing 20 and the second housing 30 are made of non-magnetic material, but one or both of the first housing 20 and the second housing 30 are made of resin. You may

The invention is not limited by the above examples and drawings. Modifications (including deletion of components) can be made as appropriate without changing the gist of the present invention.

1 Stroke sensor 10 Detection shaft 11 Large diameter portion 12 Medium diameter portion 13 Small diameter portion 14 Retaining ring 15 Airtight member 18a First washer 18b Second washer 20 First housing 20a Cylindrical portion 20b Flat plate portion 21 First receiving portion 22 shaft support portion 23 first washer support portion 30 second housing 31 second receiving portion 32 hole portion 33 shaft hole 34 second washer support portion 35 chamfered portion 40 spring 50 substrate 51 magnet 52 magnetic detection element 60 Third housing O Origin position S Movement amount

Claims (5)

A stroke sensor that detects the amount of movement of a detection shaft that follows an object to be detected and moves from an origin position,
the sensing shaft having an enlarged diameter portion, a first washer and a second washer;
a first housing supporting the detection shaft;
a second housing supporting the sensing shaft;
a spring that returns the detection shaft to the origin position after moving from the origin position;
a magnet for changing the magnetic field as the detection shaft moves;
a magnetic detection element that detects the amount of movement of the detection shaft from changes in the magnetic field accompanying the movement of the detection shaft;
with
The first housing has a first receiving portion that receives the large diameter portion,
the second housing has a second receiving portion for receiving the first washer;
the first washer and the second washer are in contact with the spring;
the first receiving portion and the second receiving portion limit the amount of movement of the detection shaft;
A stroke sensor characterized by: The detection shaft further has a retaining ring,
the first housing further having a first washer support;
When the detection shaft moves toward the first housing, the second washer supported by the retaining ring pushes the spring, and the first washer supported by the first washer support portion pushes the spring. a washer supports the spring;
The stroke sensor according to claim 1, characterized in that: the second housing further comprises a second washer support;
When the detection shaft moves toward the second housing, the first washer supported on the large diameter portion pushes the spring, and the second washer support supports the spring. a second washer supports the spring;
The stroke sensor according to any one of claims 1 and 2, characterized in that: the second housing further comprises a shaft hole through which the detection shaft passes;
The shaft hole has a chamfered portion formed by chamfering a corner of the shaft hole in the direction of the large-diameter portion of the detection shaft,
The stroke sensor according to any one of claims 1 to 3, characterized in that: The stroke sensor further comprises a third housing,
The detection shaft has the magnet,
The third housing includes a storage portion that stores a substrate having the magnetic detection element,
The stroke sensor according to any one of claims 1 to 4, characterized in that:

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