JP2591541Y2 - Acceleration sensor - 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 sensor for outputting a resistance change of a semiconductor strain gauge as an electric signal.

[0002]

2. Description of the Related Art The structure of a conventional acceleration sensor is shown in FIGS.
It will be described based on. In FIG. 1, reference numeral 1 denotes a flat metal stem, and a plurality of through holes are formed in a peripheral portion thereof.
Lead terminals 3 for electrical connection with the outside are fixed by welding the hard glass 2 to each of the plurality of through holes. Thus, the lead terminal 3 and the stem 1 are electrically insulated by the hard glass 2 and the hard glass 2 is interposed with good airtightness. On the stem 1, a sensor element including a cantilever 4 and a pedestal 5 is mounted.

In the cantilever 4, a thin beam portion 6 is formed by etching a substrate, and a free end 7 is formed in the thick portion so that a part thereof can be displaced in accordance with the acceleration to be measured. Are formed. The other end is fixed to the pedestal 5. Also, strain gauges are formed in the beam portion 6 in a full bridge shape, for example, and the wire gauges 9 are electrically connected to the lead terminals 3 by wire bonding . Reference numeral 8 denotes a stopper, which has an inverted L-shape and is erected, and has a free end 7 of the cantilever 4.
Is regulated upward.

[0004] Reference numeral 10 denotes a metal shell in which a flange portion 11 is formed over the entire periphery at a peripheral portion, and a portion other than the flange portion 11 is formed with a concave portion by press working to form a box shape. 1 and hermetically sealed by welding. The hermetic sealing is performed by removing the shell 10 from above so that the periphery of the stem 1 coincides with the flange 11 of the shell 10.
After contacting the two peripheral parts, the two parts are welded by applying a current to the contact surface between the shell 10 and the stem 1 while applying pressure by a press.

[0005] When acceleration is applied to the semiconductor acceleration sensor configured as described above from the outside in the vertical direction, the free end 7 of the cantilever 4 vibrates in the vertical direction, and as a result, the beam portion 6 is distorted. Occurs. The resistance value of the semiconductor strain gauge changes according to the magnitude of the strain, and is detected as an electric signal.

However, in the welding of the flat metal stem 1 and the metal shell 10 as described above, since the peripheral edges of the metal stem 1 and the metal shell are pressed by a machine from the upper and lower directions A, the current is welded by contact. As a result, high heat is generated, and fine molten metal splash powder scatters as a splash 14 toward the inside of the shell 10 as shown in FIG. 8, thereby causing a circuit failure later. Therefore, in the case of mass-produced products, welding conditions for preventing the generation of the splash 14 have been experimentally determined by taking a lot of time and man-hours.

In the case where a large number of products are not produced, FIG. 9 and FIG.
(No. 59075), a portion excluding the peripheral portion of the stem 1 (a portion excluding the flange portion 11 of the shell 10 and a portion facing the concave portion of the shell 10) is protruded as indicated by reference numeral 26 by press working. The protrusions 26 are engaged so that the peripheral edge rising side surfaces 12 of the projections 26 contact the rising wall surfaces 13 of the inner wall surfaces of the metal shell 10.
The passage scattered in the internal space is closed to prevent the splash 14 from scattering.

[0008]

[Devised Problems to be Solved] even in the splash scattering prevention means of small quantity production oriented in this manner, a press machine the stem 10 to generate a large pressure for pressing is required equipment costs, expenses And ultimately boosted product costs.

The present invention has been made to solve the above-mentioned problems, and has as its object to prevent splashes from being scattered with an inexpensive structure and to solve the above-mentioned problems.

[0010]

According to this acceleration sensor,
The first invention is a metal stem sensor element is mounted is covered from above with a metal shell, and a flange portion formed on the peripheral portion of the metallic shell is welded to the peripheral portion of the metal stem, the In an acceleration sensor in which a sensor element is hermetically sealed, an inner corner of a flange of the metal shell is provided.
Is formed over the entire circumference of the step, and the upper wall of the step is formed.
O-ring between the horizontal wall and the top of the metal stem
Or O-ring or packing
The metal shell is sandwiched between the flange of the metal shell and the metal stem.

[0011] The second device is the above-described gold in the first device.
Formed around the entire inner corner of the flange of the metal shell
A concave groove is provided on the upper surface of the metal stem below the step, and
Position the O-ring in the groove of
Sandwiched between the flange of the metal shell and the metal stem.
It is characterized by having incorporated.

[0012]

According to the above construction, the splash direction
Since the O-ring or the packing is arranged, splash is prevented from being scattered inside the acceleration sensor during welding.

[First Embodiment] An embodiment according to the present invention will be described in detail with reference to FIGS. 1, 2 and 3. FIG. 1, 2, and 3, the same or equivalent components as those described in FIGS. 6 to 10 are denoted by the same reference numerals, and detailed description thereof will be omitted. 1, 2, and 3, reference numeral 20 denotes a heat-resistant O-ring (splash scattering prevention means), which is disposed on the flat stem 1 so as to surround the sensor element. Reference numeral 24 denotes a step formed over the entire inner peripheral corner of the flange 11 of the shell 10, and an O-ring 20 is provided between the horizontal wall forming the upper wall thereof and the upper surface of the stem 1. It is pressed and pinched from the direction.

In this method, the O-ring 20 is sandwiched between the step 11 of the shell 10 and the stem 1, and pressure is applied to the O-ring 20 from the upper and lower directions A to bring both opposing surfaces into contact with each other. Thereafter, a current is applied in the vertical direction through the contact surface to weld the contact surface. At this time, the splash 14 scattered toward the inside of the shell 10 is obstructed by the O-ring 20 and scatters into the shell 10. There is no.

[Second Embodiment] This embodiment is different from the first embodiment shown in FIG. 3 in that a packing 2 is used instead of an O-ring as a splash scattering prevention means.
1 is used. The other parts in FIG. 4 are the same as or equivalent to those shown in FIG. 3, and a description thereof will be omitted.

[Third Embodiment] This embodiment is different from the first embodiment shown in FIG. 3 in the following point, and the other parts in FIG. 5 are the same as those shown in FIG. The description is omitted because it is equivalent. Immediate Chi, different from, the periphery and the shell 10 of the stem 1
In the contact surface with the flange portion 11, the stem 1 side has a width such that the O-ring 20 is slightly lowered below the O-ring 20 along the position where the O-ring 20 is disposed. Groove 22 is formed in a ring shape. Further, a convex portion 23 having a V-shaped cross section is formed on the flange portion 11 of the shell 10 so as to protrude downward so as to be located over the entire circumference and outside the concave groove 22. In this embodiment, the packing 2 shown in FIG.
Needless to say, it may be 1.

[0017]

As has been described above devised], according to the invention, the stepped portion over the entire periphery of the inner corner portion of the flange portion of the metallic shell
The horizontal wall and the metal switch forming the upper wall of the step
Place an O-ring or packing between the top of the system and
Replace the O-ring or packing with the metal shell flange and gold
O-ring
Even if the vertical dimension of the packing and packing is large, it is absorbed by the step
When welding the metal stem and the metal shell.
The effect is that the external force to be contacted is small.
You. Also, this makes it possible to use a thick O-ring etc.
Can effectively prevent the spread of splash
The effect is exhibited. Further, an effect that a high-quality acceleration sensor can be obtained without a large capital investment is exhibited. In addition, the metal shell is concave
The O-ring can be positioned without providing a groove,
The external dimensions of the accelerometer need not be increased.
Cormorant effect has and can be reduced is exhibited.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a structure of a stem side of an acceleration sensor according to the present invention.

FIG. 2 is an explanatory cross-sectional view of the first embodiment of the acceleration sensor according to the present invention;

FIG. 3 is an enlarged explanatory view of a main part of the first embodiment shown in FIG. 2;

FIG. 4 is an enlarged explanatory view of a main part for describing a second embodiment according to the present invention.

FIG. 5 is an enlarged explanatory view of a main part for describing a third embodiment according to the present invention.

FIG. 6 is an explanatory diagram for explaining a conventional acceleration sensor.

FIG. 7 is an explanatory cross-sectional view illustrating a structure of a conventional acceleration sensor.

FIG. 8 is an explanatory diagram for explaining a problem of a conventional example.

FIG. 9 is an explanatory diagram for explaining another conventional example.

FIG. 10 is an explanatory sectional view of the acceleration sensor shown in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stem 4 Cantilever 5 Pedestal 6 Beam part 7 Free end 8 Stopper 10 Shell 20 O-ring 21 Packing 22 Concave groove 23 Convex part 24 Step part

Claims (2)

(57) [Scope of request for utility model registration] 1. A metal stem (1) on which a sensor element is mounted is covered from above by a metal shell (10), and a flange (1) formed on the periphery of the metal shell (10).
1) and welded to the peripheral portion of the metal stem (1), in the acceleration sensor formed by hermetically sealing said sensor element, the inner corner of the flange portion (11) of said metallic shell (10)
Form a step over the entire circumference of the part and form the upper wall of the step
Between the horizontal wall and the upper surface of the metal stem (1).
Place the ring or packing (20), (21)
O-ring or packing (20), (21) in front
An acceleration sensor, which is sandwiched between a flange (11) of a metal shell (10) and the metal stem (1). 2. A collar (1) of the metal shell (10).
1) The lower part of the step formed over the entire periphery of the inner corner portion
A concave groove (22) is provided on the upper surface of the metal stem (1);
Position the O-ring in the groove, and
The flange (11) of the metal shell (10) and the metal
Contracted between the stem and the stem (1)
The acceleration sensor according to claim 1.