JP3476622B2 - Acceleration switch and method of assembling the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration switch whose contacts are opened or closed by detecting acceleration.

[0002]

2. Description of the Related Art An acceleration switch is used by being installed in a controller such as a suspension of a vehicle or an airbag. That is, the acceleration switch includes a magnet that moves when acceleration is applied and a reed switch that opens or closes with the moved magnet, and detects a change in vehicle speed, that is, that the vehicle acceleration exceeds a predetermined value. An acceleration switch having such a structure is disclosed in Japanese Patent Laid-Open No. 2-203276.

[0003]

The acceleration switch using the reed switch having the above structure has the following problems. That is, the reed switch is 2
Two leads are typically provided, the two leads being spaced apart and parallel to each other. Then, when the magnetism of the magnet acts on the lead by a predetermined amount or more, the contacts provided at the opposite ends of the lead are closed. However, the reed switch has a problem in that the on or off characteristics of the reed differ due to the difference in the distance between the contacts depending on the product, and variations occur, resulting in non-uniform quality. Therefore, even if the magnetic field acts on the lead, the magnetic field acting between the contact points is weak in the case where the contact points are separated by a predetermined value or more, and the contact points do not close and do not contact each other. On the other hand, when the contacts are close to each other by a predetermined value or less, the contacts may come into contact with each other to perform the ON operation even if the magnetic amount is weak. As described above, if the quality of the reed switch, that is, the operating point is not uniform, there is a problem that the detection of acceleration is not stable.

An object of the present invention is to provide an acceleration switch that can reliably operate at a predetermined acceleration even if a reed switch having such variations is used.

[0005]

In order to achieve the object, the invention of claim 1 is such that a magnet that moves when acceleration is applied and a contact provided on a lead when the magnet moves by acceleration is a magnetic field of the magnet. In a method of assembling an acceleration switch having a reed switch that opens or closes at, the reed switch rotates about the longitudinal direction of the reed switch so that the reed switch has a predetermined sensitivity to the magnet. It is characterized in that the orientation is adjusted and the reed switch contact point with respect to the magnet is arranged in the adjusted orientation.

According to a second aspect of the present invention, a magnet moves when acceleration is applied, a reed switch in which a contact provided on the reed is opened or closed by magnetism of the magnet when the magnet moves under acceleration, the magnet and the reed. In the acceleration switch in which the switch is housed in the case, the reed switch has an index provided at a position having a predetermined sensitivity to the magnet, and the index is made to coincide with a predetermined position in the case. Characterize.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described.
This will be described with reference to the drawings.

1A and 1B are views showing the outer shape of an acceleration switch according to an embodiment of the present invention. This acceleration switch is provided with a case 1 made of synthetic resin, and as shown in FIG. 2, a cylindrical hollow portion 11 is provided in the upper portion of the case 1 along the longitudinal direction.
Has one end closed and the other end open. Further, hemispherical bosses 11B are provided on wall surfaces 11A at one closed end of the hollow portion 11, respectively. Also, on the inner peripheral surface of the opening part which is the open part at the other end,
A step 11C is provided.

Further, a cylindrical magnet 12 is inserted into the hollow portion 11, and the outer diameter of the magnet 12 is slightly smaller than the inner diameter of the hollow portion 11. As a result, the magnet 12 moves inside the hollow portion 11
It becomes possible to move in two axial directions. Magnet 1
After inserting 2, the spring 13 is further inserted into the hollow portion 11, and thereafter, the opening portion at the other end of the hollow portion 11 is closed by the cap 14.

On the other hand, a peripheral groove 14A is provided on the side wall of the peripheral surface of the cap 14, and an O-ring 14B is attached to the peripheral groove 14A. This O-ring 14
B prevents moisture and the like from entering the inside of the hollow portion 11. In addition, a cylindrical protrusion 14C having a hemispherical tip is provided in the center of the cap 14 so as to face the hollow portion 11.

The spring 13 is contracted by the cap 14, and the magnet 12 is pressed toward the wall surface 11A by the elastic force of the spring 13. However, the side surface 12A of the magnet 12 is moved toward the wall surface of the hollow portion 11 by the action of the boss 11B. 11A is prevented from sticking. Moreover, since the magnet 12 is movably inserted into the hollow portion 11,
When a force due to acceleration is applied to the magnet 12, the magnet 12 moves against the elastic force of the spring 13 toward the other end opening portion of the hollow portion 11. The protrusion 14
C has a stopper function and its height is spring 13
The wire rods are set so as to prevent them from sticking to each other, and the reed switch 15 is set to be closed while the magnet 12 is in contact with the protrusion 14C.

As described above, the magnet 12 that moves by the action of acceleration is installed on the upper part of the case 1.
Further, as shown in FIG. 3, a storage portion 16 for storing the reed switch 15 is provided at the bottom of the case 1. 3A is a cross-sectional side view of a main part of the case 1, and FIG. 3B is a bottom view of the case 1. The storage portion 16 includes the terminal mounting portions 161, 162 and the terminal mounting portion 1.
63, 164, holding portions 165, 166 for holding the reed switch 15 from the side, and positioning portions 167, 168.
With.

The terminal mounting portion 161 of the housing portion 16 is used as a set with the terminal mounting portion 162.
61 and 162 are provided with grooves 161A and 162A,
In addition, terminals 17 described later are attached to the grooves 161A and 162A. Similarly, the terminal mounting portion 163 is used as a set with the terminal mounting portion 164, and groove 163A, 164A is provided in each of the terminal mounting portion 163, 164, and the groove 163A, 164A will be described later. Terminal 1
7 is attached.

That is, one of the terminal mounting portions 161, 16
The terminal 17 shown in FIG. 4 is attached to the second and other terminal attaching portions 163 and 164. The terminal 17 has a U-shape (or a U-shape), and the reed switch 15 housed in the housing 16 is located inside the pair of terminal portions 17A, 17A formed at the ends thereof. It is tightened. Also,
A connecting portion 17B for welding the leads 15B and 15C of the reed switch 15 is provided between the pair of terminal portions 17A and 17A. Such terminal 17
The pair of terminal portions 17A, 17A of
Grooves 161A and 162A of 162 and terminal mounting portion 163.
The grooves 163A and 164A of 164 are fitted and attached.

Further, the holding portions 165 and 166 of the storage portion 16 are provided.
Are U-shaped, and the U-shaped shape is utilized, that is, the main body 15A of the reed switch 15 is sandwiched between the holding portions 165 and 166 on both side portions, and the reed switch 15 is formed at the U-shaped bottom portion. The main body 15A is held. As a result, the holding units 165 and 166 are connected to the reed switch 15
The reed switch 15 is held so that is located at a predetermined position in the case 1. That is, this predetermined place is
The magnet 12 moved by acceleration is the reed switch 15
It is a place facing the contact points 15D and 15E.

The reed switch 15 has one reed 15
Contact 15D provided at the end of B and the other lead 15
Between the contact 15E provided at the end of C and the magnet 1
When the magnetism of 2 acts, mutual contact points 15D,
15E is a switch that opens and closes, and the reed switch 15 generally has contacts 15D and 15E and a magnet 1
They have different sensitivities depending on the relative positional relationship between the two. This point will be described below.

First, the reed switch 15 has a predetermined reference arrangement relative to the magnet 12. The reference arrangement is, as shown in FIG. 5, contact points 15D,
Longitudinal direction of end face of 15E (hereinafter referred to as contact direction A)
Is the arrangement when facing the magnet 12. Also,
The reed switch 15 is arbitrarily arranged in advance. As shown in FIG. 6, this arbitrary arrangement is an arrangement in which the reed switch 15 is rotated by an angle θ with respect to the contact direction A in the reference arrangement.

The moving distance x of the magnet 12 when the contacts 15D and 15E are closed is measured when the magnet 12 is moved by setting the reed switch 15 to the above-mentioned standard arrangement or arbitrary arrangement. As shown in FIG. 7, the moving distance x of the magnet 12 is equal to the contact points 15D, 1 of the reed switch 15.
It is the distance x from the center line L passing through the center of 5E to the magnet 12, and the measurement result of the moving distance x is as shown in FIG. In FIG. 8, the reference arrangement, the angle θ is 1
It is shown that the sensitivity of the reed switch 15 is the same at the same movement distance x in each of the arbitrary arrangement of 80 degrees and the arbitrary arrangement of the angle θ of 360 degrees, and the angle θ is 90 degrees. The distance x from the magnet 12 to the center line L of the contacts 15D, 15E when the contacts 15D, 15E close near the disposition is the longest, that is, the sensitivity of the magnet 12 is the lowest. Furthermore, the angle θ is 270
The distance x from the magnet 12 to the contacts 15D and 15E when the contacts 15D and 15E are closed near an arbitrary position, which is the degree, is the shortest, and the sensitivity of the magnet 12 is the highest. That is, the sensitivity curve shown by the solid line in FIG. 8 is a standard sensitivity characteristic, and the characteristic may move up and down in parallel due to product variations.

However, the actual reed switch 15
Then, the bending characteristics of the leads 15B and 15C (due to cantilever support), the relative position and distance between the contacts 15D and 15E,
Since the sensitivity characteristic curve is distorted differently depending on the conditions such as the parallelism of the contacts 15D and 15E, when the reed switch 15 having such variations is used, if the value of the moving distance required for setting is x ₀ , The sensitivity characteristic curve has one lead 15B (or 15) in the direction of the angle θ corresponding to the value x _0.
Bend C). For example, in the case of the characteristic curve shown by the solid line in FIG. 8, it is bent in the direction of 180 degrees, and in the case of the characteristic curve shown by the broken line, it is bent in the direction of θ = 220 degrees. That is, in the reed switch 15 having an ideal sensitivity characteristic, as shown in FIG. 9, the lead 15C is bent at about 90 degrees with respect to the contact direction A in the standard arrangement,
The bent portion 15F is formed. In this embodiment, the bent portion 15F and the positioning portions 167 and 168 constitute the adjusting means.

When the reed switch 15 having low sensitivity is used, as shown in FIG. 10, the reed switch 15 in the state shown in FIG. When operating at the movement distance x ₀ , the lead 15C is bent in the horizontal direction in the activated state to form the bent portion 15F.

Thus, the bent portion 15 is formed on the lead 15C.
The lead 15 having the F formed thereon has positioning portions 167, 168.
Attached to.

The positioning portions 167 and 168 determine the position of the reed switch 15 with respect to the magnet 12. For this reason, the positioning portion 167 is provided with a groove 167A as shown in FIG. The tip portion of the lead 15B of the reed switch 15 which is not bent is inserted into the groove 167A and abutted and positioned. Positioning part 16
As shown in FIG. 11, No. 8 forms a groove 168A by the pillar portions 168B and 168C. At this time, one pillar part 1
68C is low, that is, the height of the pillar portion 168C is as follows when the holding portions 165 and 166 hold the reed switch 15.
Bending part 15F of reed 15C of reed switch 15
Is set so as to hit the surface portion 168D of the pillar portion 168B.

The positioning portions 167 and 168 determine the position of the reed switch 15 with respect to the magnet 12, that is, the position of the reed switch 15 with respect to the hollow portion 11. As a result, the magnet 12 moves the standard moving distance x
When moving to ₀ , the reed switch 15 is always closed.

Such an acceleration switch is assembled as follows. The magnet 12 and the spring 13 are inserted into the hollow portion 11 of the case 1 in this order. Then, the opening 14 of the hollow portion 11 is capped with an O-ring.
Block with.

On the other hand, the magnet 12 is connected to the contact 15
While maintaining the distance x ₀ away from the center line L of D and 15E, the magnet 12 is rotated little by little, and the contacts 15D and
When 15E is closed, the angle θ is maintained and one lead 15 is bent 90 degrees in the horizontal direction to form a bent portion 15F for adjustment.

After that, the lead 17 is attached to the case 1,
The lead 15B of the reed switch 15 of the housing portion 16 is put into the groove 167A of the positioning portion 167, and the lead 15C is put into the positioning portion 168 while being brought into contact with each other. Holding part 1
When 65 and 166 hold the reed switch 15, the reed switch 15 is rotated to move the bent portion 15F of the lead 15C to the pillar portion 168 as shown in FIG.
Press on the surface portion 168D of B. After this, lead 15
B and 15C are welded to the connecting portion 17B of the terminal 17. After that, urethane or the like is injected into the storage portion 16 to fix the reed switch 15 to the storage portion 16. Thus, the acceleration switch is made.

As described above, since the reed switch 15 is mounted by rotating the reed switch 15 by a predetermined angle around the axis according to the variation of the operation sensitivity characteristic of the reed switch 15, the influence of the variation of the reed switch 15 is eliminated.
Since the magnet 15 can be turned on only when the magnet 15 moves by a predetermined amount x ₀ , the acceleration can be reliably detected. For this reason, in this embodiment, since the bent portion 15F is formed on the reed switch 15 and the positioning portions 167 and 168 are formed on the case 1,
It is possible to suppress an increase in the production cost of the acceleration switch.

[0028]

As described above, according to the present invention,
Since the sensitivity of the reed switch changes by changing the direction of the contact centering on the longitudinal direction of the reed,
There is no need for selection in the inspection process, and all reed switches can be used by just adjusting. That is, since the reed switch whose contact direction is adjusted according to the sensitivity of the reed switch is arranged around the magnet, it is possible to reliably detect the acceleration even when the reed switch having the uneven sensitivity is used. It is possible to deal with uneven sensitivity.

[Brief description of drawings]

FIG. 1 is a side view and a front view showing an acceleration switch according to an embodiment of the present invention.

FIG. 2 is a diagram showing insertion of a magnet 12.

FIG. 3 is a diagram showing a storage portion 16 of a reed switch 15.

FIG. 4 is a perspective view showing a terminal 17.

FIG. 5 is a diagram showing a standard arrangement of reed switches 15.

FIG. 6 is a diagram showing an arrangement of reed switches 15 different from the reference arrangement.

FIG. 7 is a diagram showing an arrangement of a reed switch 15 and a magnet 12 for checking sensitivity.

8 is a diagram showing the sensitivity of the reed switch 15. FIG.

9 is a bent portion 1 formed on the reed switch 15. FIG.
It is a figure which shows 5F.

10 is a view showing a bent portion 15F formed on the reed switch 15. FIG.

FIG. 11 is a cross-sectional view showing the I-I cross section of FIG. 3;

[Explanation of symbols]

12 magnets 13 spring 14 cap 15 reed switch 15B, 15C lead 16 Storage 167,168 Positioning unit

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01P 15/135 B60R 21/32 H01H 35/14 H01H 36/00 301

Claims (2)

(57) [Claims] 1. A method of assembling an acceleration switch, comprising: a magnet that moves when acceleration is applied; and a reed switch that a contact provided on a reed opens or closes due to the magnetism of the magnet when the magnet moves by acceleration. Rotate the reed switch lead about the longitudinal direction of the reed switch to adjust the direction of the contact to the magnet so that the reed switch has a predetermined sensitivity to the magnet. A method of assembling an acceleration switch, characterized in that 2. A magnet that moves when acceleration is applied, a reed switch that opens or closes a contact provided on a reed by the magnetism of the magnet when the magnet moves by acceleration, and a magnet and a reed switch in a case. In the accelerometer switch housed in the reed switch, an index is provided at a position having a predetermined sensitivity to the magnet, and the index is matched with a predetermined position in the case. .