JP7478893B1 - Pressure detection sensor - Google Patents

Abstract

[Problem] To provide a pressure detection sensor that is unlikely to experience poor contact or detection errors over a long period of time and has a long life. [Solution] The shape of the leaf spring portion 8B and the positional relationship between the first contact contact portion 9 and the first fixed contact portion 4 are determined so that the first contact contact portion 9 comes into contact with the first fixed contact portion 4 only when a pressing force is applied to the operated portion 2, and the first contact contact portion 9 goes into a non-contact state with the first fixed contact portion 4 when the application of pressing force to the operated portion 2 is released. The first contact contact portion 9 is disposed between the pressed portion 8c of the leaf spring portion 8B pressed by the pressing portion 2A and the base portion 8D of the leaf spring portion 8B. [Selected Figure] Figure 4

Description

The present invention relates to a pressure detection sensor that detects whether or not pressure is applied.

A typical pressure detection sensor is a so-called seating sensor that detects whether or not someone is sitting in the passenger seat or the back seat of a vehicle. The seating sensor is placed inside the passenger seat or the back seat and detects the pressure applied to the seat when someone sits in the passenger seat or the back seat.

Figures 1 to 5 of Chinese Utility Model Registration No. CN213734901 (Patent Document 1) disclose an exploded perspective view of an example of a conventional pressure detection sensor. In the following explanation of the background art, the symbols shown in Figures 1 to 5 of Patent Document 1 will be used. The conventional pressure detection sensor shown in Figures 1 to 5 of Patent Document 1 comprises a case body 1 formed of an electrically insulating material having an opening on one side, an operated part 2 slidably fitted onto the case body so as to cover the opening of the case body 1, an elastic member 4 arranged between the operated part 2 and the case body 1 and configured to store energy when a pressing force in a direction toward the case body 1 is applied to the operated part 2 and to release energy so as to return the operated part 2 to its original position when the pressing force is released, a first fixed contact portion and a second fixed contact portion (8) fixed to the bottom wall portion of the case body 1 facing the opening, and a contact plate 3 arranged within the case body 1 and integrally comprising a first contact contact portion that contacts the first fixed contact portion (8) when a pressing force is applied to the operated part 2 and a second contact contact portion that is constantly in contact with the second fixed contact portion (8). The contact plate 3 has a first contact part on a leaf spring part 10 that is deformed by being pressed by a pressing part 9 (FIGS. 3 to 5) provided on the operated part 2 when a pressing force is applied to the operated part 2, and returns to its original shape when the application of the pressing force to the operated part 2 is released. The first contact part is located on the pressed part of the leaf spring part 10 that is pressed by the pressing part 9 or in the vicinity of the pressed part.

EP 3526806 (Patent Document 2) also discloses a conventional pressure detection sensor that uses a plate spring to return the operated part, and the first contact point is located in the pressed part of the leaf spring part that is pressed by a pressing part provided on the operated part.

China Utility Model Registration No. CN213734901 EP 3526806B

In the pressure detection sensor described in Patent Document 1, the first contact point is disposed at or near the pressed portion of the leaf spring portion 10 that is pressed by the pressing portion 9 of the operated portion 2, and the first contact point receives the direct pressing force from the pressing portion 9 of the operated portion 2 together with the impact, so the first contact point is prone to wear and deformation. This makes the contact point prone to contact failure and shortens its lifespan.

The pressure detection sensor in Patent Document 2 also has the same problems as the pressure detection sensor in Patent Document 1.

The objective of the present invention is to provide a pressure detection sensor that is unlikely to experience contact failure or detection errors over a long period of time and has a long lifespan.

The pressure detection sensor of the present invention comprises a case body 1 formed of an electrically insulating material having a sensor storage section 1A with an opening 1a on one side, an operated part 2 movably fitted to the case body 1 so as to close the opening 1a of the case body 1, an elastic member (3) arranged between the operated part 2 and the sensor storage section 1A and configured to store energy when a pressing force is applied to the operated part 2 in a direction toward the case body and to release energy so as to return the operated part 2 to its original position when the pressing force is released, a first fixed contact part 4 and a second fixed contact part 5 fixed to the bottom wall part 1b of the sensor storage section 1A facing the opening 1a, and a contact plate 8 arranged within the sensor storage section 1A and integrally provided with a first contact contact part 9 that contacts the first fixed contact part 4 when a pressing force is applied to the operated part 2 and a second contact contact part 10 that is constantly in contact with the second fixed contact part 5. The contact plate 8 has a first contact contact portion 9 on a leaf spring portion 8B that is pressed and deformed by a pressing portion 2A provided on the operated portion 2 when a pressing force is applied to the operated portion 2, and returns to its original shape when the application of the pressing force to the operated portion 2 is released. The shape of the leaf spring portion 8B and the positional relationship between the first contact contact portion 9 and the first fixed contact portion 4 are determined so that the first contact contact portion 9 contacts the first fixed contact portion 4 only when a pressing force is applied to the operated portion 2, and the first contact contact portion 9 is in a non-contact state with the first fixed contact portion 4 when the application of the pressing force to the operated portion 2 is released. In the present invention, the first contact contact portion 9 is disposed between the pressed portion 8c of the leaf spring portion 8B pressed by the pressing portion 2A and the base portion 8D of the leaf spring portion 8B.

According to the present invention, the pressing force applied to the operated part is not directly applied to the first contact point part 9, but is applied to the first contact point part 9 and the first fixed contact part 4 via the buffering effect of the deformation of the leaf spring part 8B, so that the first contact point part 9 is less likely to wear or deform, and a longer life can be achieved.

The pressing portion 2A of the operated portion 2 is preferably provided in the center of the back surface of the operated portion 2 that faces the bottom wall portion 1b of the case body 1, and the bottom wall portion 1b of the case body 1 is preferably formed with a recess 1c that receives the pressed portion 8c of the leaf spring portion 8B that is pressed and deformed by the pressing portion 2A. In this way, the pressing force applied to the operated portion 2 is transmitted evenly to the leaf spring portion 8B, and the deformation of the leaf spring portion 8B is increased, thereby improving the cushioning properties of the leaf spring portion 8B.

It is preferable that the first fixed contact portion 4 is provided near the outside of the opening of the recess 1c. In this way, the force from the leaf spring portion 8B deformed within the recess 1c can be applied to the first fixed contact portion 4 to the maximum extent.

It is preferable that the first fixed contact portion 4 consists of two fixed contacts 4a arranged along the edge of the opening of the recess 1c, and the first contact contact portion 9 consists of two contact contacts 9a facing the two fixed contacts 4a. This reduces the contact resistance.

The case body 1 is a resin molded product, and the first fixed contact portion 4 and the second fixed contact portion 5 may be insert-molded into the bottom wall portion 1b of the case body 1 as inserts. This structure makes it easy to fix the fixed contact portions.

The contact plate 8 can be composed of a metal plate having an annular body 8A, a leaf spring portion 8B integrally provided on the inner periphery of the annular body and extending toward the center of the annular body 8A, and a tongue-shaped portion 8C provided on the inner periphery of the annular body with a space in the circumferential direction of the annular body 8A from the leaf spring portion 8B and extending toward the center and including a second contact point portion 10. In addition, a plurality of protrusions 1e, 1f for positioning the contact plate 8 are integrally provided on the bottom wall portion 1b of the sensor storage portion 1A, and the contact plate 8 may be fixed to the bottom wall portion 1b with at least one of the plurality of protrusions 1f being heated and deformed. By adopting such a configuration, the contact plate does not move within the sensor storage portion due to external vibrations, and false detection due to vibration of the contact plate can be prevented.

The elastic member (3) is made of a coil spring that abuts against the annular body 8A of the contact plate 8, and it is preferable that the base 8D of the leaf spring portion 8B and the base of the tongue portion 8C abut against the coil spring 3. In this way, the leaf spring portion 8B and the tongue portion 8C can be prevented from vibrating more than necessary due to external vibrations of the coil spring.

The present invention provides a pressure detection sensor that is unlikely to experience contact failure or detection errors over a long period of time and has a long lifespan.

1 is a plan view of an embodiment of a pressure detection sensor of the present invention; 2 is a cross-sectional view taken along line II-II in FIG. 1, showing an internal mechanism of the pressure detection sensor when no pressure is being applied. 2 is a cross-sectional view taken along line II-II in FIG. 1, showing an internal mechanism of the pressure detection sensor when a pressure is applied. FIG. 3 is an enlarged view of a part of FIG. 2 . 11 is a plan view of the inside of the sensor storage section with the contact plate inserted, as viewed from the opening side. FIG. 13 is a plan view of the inside of the sensor storage section without the contact plate inserted, as viewed from the opening side. FIG. 1A to 1C are diagrams used to explain details of a contact plate according to an embodiment and an operating state of a contact of a pressure detection sensor. FIG. 13 is a diagram used to explain a situation that occurs when there is one contact contact and one fixed contact.

Below, we will explain in detail one embodiment of the pressure detection sensor of the present invention with reference to the drawings.

＜Overall＞
FIG. 1 is a plan view of a pressure detection sensor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 showing the internal mechanism of the pressure detection sensor when no pressure is applied, and FIG. 3 is a cross-sectional view taken along line II-II in FIG. 1 showing the internal mechanism of the pressure detection sensor when a pressure is applied. In addition, hatching showing a cross section is omitted in FIG. 2 and FIG. 3 to prevent the view from becoming unclear. As shown in FIG. 1 to FIG. 3, the pressure detection sensor of this embodiment includes a case body 1, an operated portion 2, a coil spring 3 as an elastic member, a contact terminal member 7 having a first fixed contact portion 4 and a second fixed contact portion 5 at one end and an external terminal 6 at the other end, and being insert-molded into the case body 1, and a contact plate 8.

<Case body>
The case body 1 has a structure in which a sensor storage section 1A for storing the main part of the pressing detection sensor and an elongated terminal storage section 1B for storing the external terminal 6 are integrally formed with the sensor storage section 1A. The sensor storage section 1A has an opening 1a that opens on one side, a bottom wall section 1b facing the opening 1a, a recess 1c formed in the center of the bottom wall section 1b, and an annular peripheral wall section 1d that stands up from the bottom wall section 1b. The case body 1 is integrally molded from an electrically insulating material. Specifically, the case body 1 is molded as an integrally molded product from PBT (polybutylene terephthalate) resin, but it may be formed from other resin materials. The recess 1c is a space for the pressed portion 8c of the leaf spring section 8B of the contact plate 8 described later to enter. By providing such a recess 1c, the thickness dimension of the sensor storage section 1A can be reduced.

In this embodiment, the opening 1a surrounded by the peripheral wall 1d of the sensor storage section 1A has a substantially circular planar shape as shown in FIG. 5 and FIG. 6. However, the opening 1a of the case body 1 may have other shapes, such as a polygonal shape. The tips 7a and 7b of the first and second contact terminal member halves 7A and 7B constituting the contact terminal member 7 are insert-molded into the bottom wall 1b. The first and second contact terminal member halves 7A and 7B are electrically insulated from each other by the insulating resin material forming the case body 1. The tips 7a and 7b are arranged in a state exposed from the bottom wall 1b. As shown in FIG. 6, the tip 7a of the first contact terminal member halves 7A is integrally molded with two fixed contacts 4a constituting the first fixed contact section 4. The tip 7a is also formed with a rectangular through hole 7c that is similar in shape to the contour of the recess 1c provided in the bottom wall 1b. The two fixed contacts 4a are arranged side by side along one short side of the recess 1c and the through hole 7c. One fixed contact 5a constituting the second fixed contact part 5 is integrally molded on the tip part 7b of the second contact terminal member half part 7B. The fixed contact 5a is arranged at a position corresponding to one long side of the through hole 7c. The second fixed contact part 5 may also be composed of two fixed contacts 5a.

As shown in Figures 4 to 6, a step portion 1h is formed around the recess 1c of the bottom wall portion 1b so as to surround the tip portions 7a and 7b of the first contact terminal member half portion 7A and the second contact terminal member half portion 7B. The presence of this step portion 1h allows the leaf spring portion 8B and the tongue-shaped portion 8C of the contact plate 8 to deform in the vertical direction. Regarding the leaf spring portion 8B, in the non-pressed state shown in Figures 2 and 4, it allows the two fixed contacts 4a and the first contact contact portion 9 integrally provided with the leaf spring portion 8B to be in a non-contact state. Also, regarding the tongue-shaped portion 8C, as shown in Figure 4, it allows the one fixed contact 5a and the second contact contact portion 10 integrally provided with the tongue-shaped portion 8C to be in a constant contact state.

As shown in Figs. 5 and 6, four protrusions 1e for positioning the contact plate 8 are provided integrally at equal intervals (90 degree intervals) on the bottom wall 1b of the sensor storage section 1A. One protrusion 1f is provided on the bottom wall 1b to determine the orientation of the contact plate 8. Since the protrusion 1f is provided at an interval different from the arrangement interval of the four protrusions 1e, the protrusion 1f determines the orientation (arrangement direction) of the contact plate 8. As shown in Figs. 4 and 5, eight protrusions 1g are provided integrally at intervals in the circumferential direction across the peripheral wall 1d and bottom wall 1b of the sensor storage section 1A. These protrusions 1g are provided for positioning the contact plate 8.

<Operated unit 2>
The operated part 2 includes a pressing part 2A, and is fitted movably or slidably to the peripheral wall 1d of the sensor housing part 1A so as to close the opening 1a of the case body 1. The operated part 2 of this embodiment is integrally molded from POM (polyacetal) resin to reduce wear between the operated part 2 and the case body 1. In this embodiment, the operated part 2 constitutes a part of the case of the pressure detection sensor. The operated part 2 of this embodiment further includes a circular flat plate part 2B, an outer peripheral wall part 2C, and an inner peripheral wall part 2D. The outer peripheral wall part 2C is erected along the outer periphery of the circular flat plate part 2B and has a substantially cylindrical shape. The inner peripheral wall part 2D is provided radially inward of the outer peripheral wall part 2C of the circular flat plate part 2B and has a substantially cylindrical shape. The pressing part 2A of this embodiment is provided at the tip of a columnar part 2E extending from the center of the back surface of the operated part 2 facing the bottom wall part 1b of the case body 1 toward the bottom wall part 1b. A bottomed rectangular columnar hole 2F is formed at the center of the columnar portion 2E. The presence of this hole 2F can prevent the columnar portion 2E from being deformed. When the circular flat plate portion 2B is operated by an operator and a pressing force is applied to the operated portion 2, the pressing portion 2A deforms the pressed portion 8c of the leaf spring portion 8B of the contact plate 8. Since the pressing portion 2A has a semispherical shape, it can reliably press the pressed portion 8c even if the angle of the force pressing the operated portion 2 is different. In this embodiment, the circumferential wall portion 1d of the case body 1 is inserted between the outer peripheral wall portion 2C and the inner peripheral wall portion 2D of the operated portion 2, so that the operated portion 2 is attached to the case body 1, and the operated portion 2 can be moved smoothly.

<Coil spring>
The coil spring 3 is loosely fitted to a columnar portion 2E extending from the rear surface of the flat portion 2B of the operated portion 2, and is sandwiched between the flat portion 2B and the bottom wall portion 1b of the sensor housing portion 1A. In this embodiment, the coil spring is made of a metal spring.

The coil spring 3 is energized when a pressing force is applied to the circular flat plate portion 2B of the operated part 2 in the direction toward the case body 1 by the operator, displacing the flat plate portion 2B toward the bottom wall portion 1b, and when the pressing force toward the bottom wall portion 1b is released, the coil spring 3 is released so as to return the operated part 2 to the position before the displacement, i.e., the original position.

In particular, in this embodiment, the coil spring 3 abuts against the annular body 8A of the contact plate 8, which will be described later. Specifically, in this embodiment, the coil spring 3 abuts against the base 8D of the leaf spring portion 8B of the contact plate 8 and the base of the tongue portion 8C of the contact plate 8.

<Contact plate>
The contact plate 8 is made of a metal plate integrally provided with a first contact portion 9 and a second contact portion 10. The contact plate 8 includes an annular body 8A, a leaf spring portion 8B, and a tongue portion 8C. The outer periphery of the annular body 8A is formed with a recess 8d into which five protrusions 1e and 1f provided on the bottom wall portion 1b of the sensor storage portion 1A are fitted. The leaf spring portion 8B extends from the annular body 8A toward its inner center and beyond the inner center. The tongue portion 8C extends from a position 90 degrees away from the leaf spring portion 8B in the circumferential direction toward the inner center and to a position just before reaching the inner center.

As shown in FIG. 4, the leaf spring portion 8B is angled so that the first contact contact portion 9 does not contact the fixed contact portion 4 when the contact plate 8 is attached to the bottom wall portion 1b. The two protruding pieces constituting the contact contact 9a constituting the first contact contact portion 9 are positioned between the pressed portion 8c of the leaf spring portion 8B pressed by the pressing portion 2A and the base portion 8D of the leaf spring portion 8B (see FIG. 5). When a pressing force is applied to the circular flat portion 2B of the operated portion 2 in the direction toward the sensor storage portion 1A by the operator's operation, the leaf spring portion 8B is pressed and deformed by the pressing portion 2A provided on the operated portion 2. When the application of the pressing force to the operated portion 2 is released, the leaf spring portion 8B returns to its original shape.

In this embodiment, the shape of the leaf spring portion 8B and the positional relationship between the first contact contact portion 9 and the first fixed contact portion 4 are determined so that when a pressing force is applied to the operated portion 2, the first contact contact portion 9 contacts the first fixed contact portion 4, but when the pressing force to the operated portion 2 is released, the first contact contact portion 9 is in a non-contact state with the first fixed contact portion 4. Specifically, the positions of the two protruding pieces constituting the contact 9a are such that when the pressed portion 8c of the leaf spring portion 8 is pressed and the leaf spring portion 8 is deformed, the contact contact 9a contacts the fixed contact 4a of the first fixed contact portion 4. As shown in the figure, if the two fixed contacts 4a are arranged with a gap between them, even if dust d gets between one fixed contact 4a and one contact contact 9a, the other fixed contact 4a and the other contact contact 9a can contact each other, preventing detection errors. Incidentally, as shown in Figure 8, if dust d gets between one fixed contact 4a and one contact 9a, the dust will prevent electrical continuity between the contacts, causing a detection error. The angle of the tongue 8C is set so that the first contact 9 (9a) is always in contact with the first fixed contact 4 when the contact plate 8 is attached to the bottom wall 1b.

In the above embodiment, the two fixed contacts 4a of the first fixed contact portion 4 are provided along the edge of the opening of the recess 1c provided in the bottom wall portion 1b, so that the force from the leaf spring portion 8B deformed within the recess 1c is applied to the first fixed contact portion 4 to the maximum extent. The first contact contact portion 9 provided on the leaf spring portion 8 is composed of two contact contacts 9a facing the two fixed contacts 4a. Therefore, the pressing force applied to the operated portion 2 is not directly applied to the first contact contact portion 9, but is applied to the first contact contact portion 9 and the first fixed contact portion 4 via the buffer caused by the deformation of the leaf spring portion 8B, so that the first contact contact portion 9 is less worn and deformed, and a longer life is achieved.

In the above embodiment, the pressing portion 2A of the operated portion 2 is provided in the center of the back surface of the operated portion 2 that faces the bottom wall portion 1b of the sensor storage portion 1A, and the bottom wall portion 1b of the case body 1 is formed with a recess 1c that receives the pressed portion 8c of the leaf spring portion 8B that is pressed and deformed by the pressing portion 2A. This allows the pressing force applied to the operated portion 2 to be transmitted evenly to the leaf spring portion 8B, increasing the deformation of the leaf spring portion 8B and improving the cushioning properties of the leaf spring portion 8B.

In the above embodiment, the elastic member is made of a coil spring 3 that abuts against the annular body 8A of the contact plate 8, and the base 8D of the leaf spring portion 8B and the base of the tongue portion 8C abut against the coil spring. Therefore, the coil spring also prevents the contact plate 8 from vibrating more than necessary due to external vibrations.

The present invention provides a pressure detection sensor that is unlikely to experience contact failure or detection errors over a long period of time and has a long lifespan.

REFERENCE SIGNS LIST 1 Case body 1A Sensor storage section 1a Opening 1b Bottom wall section 1c Recessed section 1d Circumferential wall section 1e Convex section 1f Convex section 1h Step section 1g Projection section 2 Operated section 2A Pressing section 2B Flat plate section 2C Outer peripheral wall section 2D Inner peripheral wall section 3 Coil spring (elastic member)
4 First fixed contact portion 4a Fixed contact 5 Second fixed contact portion 6 External terminal 7 Contact terminal member 7A First contact terminal member half portion 7B Second contact terminal member half portion 8 Contact plate 8A Annular body 8B Leaf spring portion 8C Tongue-shaped portion 8c Pressurized portion 9 First contact contact portion 10 Second contact contact portion

Claims (7)

a case body formed of an electrically insulating material and having a sensor storage section with an opening on one surface;
an operated portion movably fitted to the sensor housing portion so as to close the opening of the sensor housing portion;
an elastic member that is disposed between the operated portion and the sensor housing portion, and that is energized when a pressing force is applied to the operated portion in a direction toward the case body, and that is deenergized to return the operated portion to an original position when the pressing force is released;
a first fixed contact portion and a second fixed contact portion fixed to a bottom wall portion of the sensor storage portion facing the opening;
a contact plate that is disposed within the sensor housing and integrally includes a first contact contact portion that contacts the first fixed contact portion when a pressing force is applied to the operated portion and a second contact contact portion that constantly contacts the second fixed contact portion;
the contact plate is provided with the first contact point portion on a leaf spring portion that is pressed and deformed by a pressing portion provided on the operated portion when the pressing force is applied to the operated portion, and returns to its original shape when the application of the pressing force to the operated portion is released;
a shape of the leaf spring portion and a positional relationship between the first contact contact portion and the first fixed contact portion are determined so that the first contact contact portion comes into contact with the first fixed contact portion only when a pressing force is applied to the operated portion, and the first contact contact portion goes out of contact with the first fixed contact portion when the application of the pressing force to the operated portion is released;
The first contact point portion is a pressure detection sensor disposed at a position between a pressed portion of the leaf spring portion that is pressed by the pressing portion and a base portion of the leaf spring portion. the pressing portion is provided at a center of a back surface of the operated portion facing the bottom wall of the sensor housing portion,
2. The pressure detection sensor according to claim 1, wherein the bottom wall portion is formed with a recess into which the pressed portion of the leaf spring portion that is pressed and deformed by the pressing portion is placed. The pressure detection sensor according to claim 2, wherein the first fixed contact portion is provided near the outside of the opening of the recess. the first fixed contact portion includes two fixed contacts aligned along an edge of the opening of the recess,
4. The pressure detection sensor according to claim 3, wherein the first contact portion comprises two contact contacts facing the two fixed contacts. the case body is a resin molded product,
2. The pressure detection sensor according to claim 1, wherein the first fixed contact portion and the second fixed contact portion are insert-molded into the bottom wall portion of the case body. the contact plate includes an annular body, the leaf spring portion provided integrally with the inner periphery of the annular body and extending toward the center of the annular body, and a tongue-shaped portion provided integrally with the inner periphery of the annular body at a distance from the leaf spring portion in the circumferential direction of the annular body, extending toward the center, and including the first contact portion;
6. The pressure detection sensor according to claim 5, wherein the bottom wall of the sensor housing portion is integrally provided with a plurality of protrusions for positioning the contact plate. the elastic member is a coil spring that abuts against the annular body of the contact plate;
7. The pressure detection sensor according to claim 6, wherein the base of the leaf spring portion and the base of the tongue-shaped portion are in contact with the coil spring.

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