JPH11201852A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor in which a case can be positioned easily by a method wherein a locking part is formed and the case for electromagnetic shielding is locked, and stopped by, a coupling so as to be positioned. SOLUTION: A pipe 13 in a state protruding partly from a pressure introduction hole 11 in a coupling 10 is welded to a pressure detecting element 20 as a lining member. Then, the inside face of a cylindrical part 22 which is formed integrally at a metal diaphragm 21 in the pressure detecting element 20 is brought into contact with the outside face of the pipe 13, the inside of the cylindrical part 22 communicates with the pressure introduction hole 11, and a hydraulic pressure acts on the pressure sensing face of the diaphragm 21. According to its detection pressure, an output means outputs an electric signal to the outside. In a case 31, for electromagnetic shielding, by which an electric circuit component 50 provided at the output means is protected from a noise, its bottom part is welded onto the mounting face 10B of the coupling 10, and the pressure detecting element 20 is housed at its inside. At this time, a protrusion part 31A which is formed at the peripheral edge in the opening part on the bottom side of the case 31 is fitted and locked by, the peripheral edge at the upper part of a positioning groove 16 which is formed as a coupling and stopping part on the outer circumferential side of the taper face 15 of the pressure introducing hole 11, and the case 31 is positioned to the coupling 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor, and more particularly, to a pressure detecting element welded to one end of a pressure introducing hole provided in a joint, and a pressure detecting element electrically connected to the pressure detecting element. The present invention relates to a pressure sensor including an electromagnetic shielding case attached to a joint while surrounding an electronic circuit component.

[0002]

2. Description of the Related Art A pressure sensor that detects a pressure difference between a detected pressure and an atmospheric pressure and converts it into an electric signal is used for measuring a fluid pressure. As shown in FIG. 4, such a pressure sensor includes, as shown in FIG. 4, a joint 10 fixed by bolting or the like to a portion to be installed, a pressure detecting element 20 attached to a welded portion 10A of the joint 10 by beam welding or the like, Output means 30 electrically connected to the detecting element 20, wherein the fluid pressure guided into the pressure introducing hole 11 of the joint 10 is converted into distortion of the diaphragm 21 forming the pressure detecting element 20,
This strain is detected by a strain gauge (not shown) on the diaphragm 21, and an electric signal corresponding to the resistance value of the strain gauge is output from the output means 30.

The output means 30 includes a case 31 attached to the joint 10 by welding or the like, and a base member 3 arranged around the pressure detecting element 20 and housed in the case 31.
An electronic circuit component 50 such as an IC, a resistor, and a capacitor which is disposed above the base member 32 and is surrounded by the case 31;
It is composed of Among these members, the case 31 is a member for electromagnetic shielding provided separately from a cover member (not shown) that forms an outer shell of the pressure sensor.
The electronic circuit component 50 is reliably protected from electromagnetic interference by being made of metal or the like.

On the other hand, in order to protect the electronic circuit component 50 from electromagnetic interference, the cover member may be made of metal. In such a case, however, the cover member is relatively large among the pressure sensors. Since it is a member, it is difficult to reduce the weight of the pressure sensor as a whole, and furthermore, it must be made into a die-cast product in order to realize a complicated shape, or it must be subjected to complicated machining, resulting in high cost. There is also a method of forming an electromagnetic shielding film by using a resin material as the cover material and applying a conductive paint on the inner surface.However, it is possible to reduce the weight, but it is still expensive, and also the joint with the joint due to the wear of the electromagnetic shielding film. There is a concern that the reliability of the conductive portion of the device may be reduced.

Therefore, providing the metal case 31 separately from the cover material can solve those problems by using the cover material as a mere resin molded product or the like, not only improving the noise resistance of the pressure sensor but also reducing the weight. There is an advantage that realization, cost reduction, and improvement in reliability can be realized.

[0006]

By the way, in the pressure sensor shown in FIG. 4, the case 31 has the joint 1 so that the pressure detecting element 20 is inserted through an opening provided at the bottom thereof.
0, it is only placed on
There is a problem that the position of the case 31 with respect to the position 0 is easily shifted, and it takes time and effort to position the case 31 when welding the case 31 to the joint 10.

An object of the present invention is to provide a pressure sensor which can easily position a case for electromagnetic shielding with respect to a joint.

[0008]

The pressure sensor according to the present invention comprises:
A pressure detecting element welded to one end of a pressure introducing hole provided in the joint, and an electromagnetic shielding case attached to the joint while surrounding an electronic circuit component electrically connected to the pressure detecting element. A pressure sensor including and comprising a joint provided with a locking portion for locking and positioning a case in the joint. In the present invention, since the engaging portion is provided on the joint, the case is easily engaged with the engaging portion, so that the case can be easily positioned, and the above object is achieved.

In the pressure sensor described above, it is preferable that the locking portion is provided in a substantially concave cross section depressed with respect to the mounting surface of the case, and the case is provided with a projection for locking with the locking portion. In such a case, since the locking portion is provided as a depression, the tip of a welding machine for welding other members or the pressure detecting element does not interfere with the locking portion, and the workability is improved.

In the pressure sensor of the present invention, particularly when the joint is fastened to the installation portion, the locking portion is formed by an annular groove provided around the welded portion to which the pressure detecting element is welded. Desirably. In such a case, the stress generated when the joint is fastened concentrates on the deep part in the depth direction of the annular groove, that is, on the part distant from the welded part. The stress applied to, for example, the diaphragm of the element is reduced, and the output value shift is prevented by preventing the diaphragm from being distorted.

Further, in the pressure sensor according to the present invention, it is preferable that the depth side of the positioning groove is provided in a state of being hollowed along the radial direction of the pressure introducing hole. In such a pressure sensor, since the stress is concentrated over the hollowed portion by providing the deep side of the groove in a recessed state, even if the depth of the groove cannot be increased, the stress is reduced. It becomes difficult to reach the detection element, and the output value shift is reliably prevented.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those described in FIG. 4 are denoted by the same reference numerals. [First Embodiment] FIG. 1 is a sectional view showing a pressure sensor 1 according to a first embodiment. The pressure sensor 1 has a joint 10 inserted into the insertion hole B of the installation target A indicated by a two-dot chain line in the drawing.
A pressure detecting element 20 beam-welded to the joint 10,
Output means 30 for outputting an electric signal to the outside in accordance with the detected pressure, and is a sensor for detecting the oil pressure in a vehicle.

The joint 10 is made of metal and is fastened to the installation portion A by a bolt C inserted through a flange 140 provided integrally. The joint 10 has a pressure introducing hole 11 penetrating vertically (in the following, upper and lower portions mean positions in the diagram, and do not necessarily mean positions when actually attached). Is provided.

A fitting portion 12 having a diameter slightly larger than that of the pressure introducing hole 11 is provided at an upper portion of the pressure introducing hole 11. It is fitted in a protruding state. And pipe 1
The diameter of the through-hole 14 provided in the pressure-introducing hole 11
, So that the volume in the pressure introducing hole 11 is adjusted to be smaller, and the pipe 13 also serves as a backing member when welding the pressure detecting element 20. Further, a tapered surface 15 as a welding portion is provided in an upper outer peripheral edge portion of the pressure introducing hole 11, and a one-step lower positioning groove 16 as a locking portion is provided on the outer peripheral side of the tapered surface 15. .

The positioning groove 16 is provided in a case 3 to be described later.
1 is used at the time of attachment, and is provided continuously in a plane annular shape. The bottom surface side of the positioning groove 16 (that is, the back side in the depth direction) is provided in a state of being hollowed inward in the radial direction of the pressure introducing hole 11.

The pressure detecting element 20 is a metal diaphragm 2
1 is a strain gauge type element (module) in which a strain gauge is provided on the upper surface via an insulating film such as silicon oxide. In this pressure detecting element 20, the diaphragm 21 is formed integrally with the lower cylindrical portion 22, and the inner surface of the cylindrical portion 22 is brought into contact with the outer surface of the pipe 13 so that the entire pressure detecting element 20 is guided. It is arranged at the upper part of the joint 10, whereby the inside of the tubular portion 22 communicates with the pressure introduction hole 11, and hydraulic pressure acts on the pressure-sensitive surface of the diaphragm 21. At the lower end of the tubular portion 22, another tapered surface 23 is provided to abut against the tapered surface 15 of the joint 10, and the tapered surfaces 15, 23 are brought into contact with each other in a direction along the inclination angle thereof. Beam welded.

The output means 30 includes a metal case 31 for electromagnetic shielding for protecting the electric circuit component 50 from noise, a resin base member 32 disposed at the bottom of the case 31 and surrounding the pressure detecting element 20. , A circuit board 33 disposed above the base member 32, and a resin connector 34 also serving as a cover member for covering the entirety of these members 31 to 33. One terminal 35 connects the circuit board 33 and the connector 34 to the second terminal 3.
6 are connected.

The case 31 is subjected to projection welding or the like in a state where the bottom portion is disposed on the mounting surface 10B of the joint 10, and the pressure detecting element 20 is housed in the case 31 through an opening provided in the center portion of the bottom. It has become.
A projection 31A bent downward by squeezing or the like is provided on the periphery of the bottom opening of the case 31, and an upper portion of the positioning groove 16 in which the projection 31A is provided in a substantially concave cross section. The case 31 is fitted and locked to the peripheral edge, whereby the case 31 is positioned with respect to the joint 10.

The case 31 is provided with a support portion 37 in which a part of the side surface is processed by pressing or cutting and raising, and the circuit board 33 is mounted on the support portion 37. Further, a contact portion 38 that is bent on the upper surface of the circuit board 33 is provided at a part of the upper edge of the case 31, and the ground line of the circuit board 33 and the case 31 (finally, The electrical connection with the joint 10) ensures that the electric circuit components 50 mounted on the lower surface of the circuit board 33 are electromagnetically shielded, and that the contact portions 38 are provided.
As a result, the circuit board 33 is securely pressed into the case 31 from above.

The lower end of the first terminal 35 is insert-molded on the base member 32. A part of the lower end of the first terminal 35 is exposed, and the exposed part is electrically connected to the above-described strain gauge of the pressure detecting element 20 by wire bonding or the like.

The connector 34 is provided with a plurality of terminals 53 which are insert-molded in a receiving member 52 made of resin, and the upper ends of the second terminals 36 are inserted through insertion holes provided at the lower ends of these terminals 53. Has been soldered. Each terminal 53 includes a receiving member 52.
The connector is fixed from the inside of the connector body 54, and only the tip is exposed. Further, the lower end side of the connector body 54 is located inside the rising portion 17 of the joint 10 via the O-ring 56, and
Is fixed to the joint 10 by caulking the tip of the joint.

In such an output means 30, the pressure acting on the diaphragm 21 of the pressure detecting element 20 is controlled by the strain gauge on the diaphragm 21 and the electric circuit on the circuit board 33 connected to the strain gauge via the first terminal 35. The electric circuit converts the electric resistance value into a predetermined electric signal, and the electric signal is output from the terminal 53 of the connector 34 via the second terminal 36.

In this embodiment, first,
The pressure detection element 20 is beam-welded to the joint 10. Next, the case 31 is arranged on the joint 10 from above, and the case 31 is positioned by locking the projection 31A of the case 31 in the positioning groove 16, and thereafter, the case is fixed to the joint 10 by projection welding. I do.
Then, after the base member 32 is arranged and adhered in the case 31, wire bonding is performed to conduct the pressure detecting element 20 and the first terminal 35. Further, the circuit board 33 is arranged from above so that the first terminal 35 is inserted into the through hole or the like, and the contact portion 38 of the case 31 is bent to fix the circuit board 33, and the first terminal 35 is soldered. Do.

Next, the terminal 53 integrated with the receiving member 52 is soldered to the second terminal 36, and the receiving member 52 is inserted into the insertion portion 69 of the connector body 54 and fixed with an adhesive or a latch. Then, connect the connector 34 to the case 31.
And finally, the connector 10 is fixed by caulking the joint 10, whereby the assembly of the pressure sensor 1 is completed. Further, when attaching the pressure sensor 1 to the installation portion A, the bolt C may be inserted into the flange portion 140 and tightened.

According to the present embodiment, the following effects can be obtained. 1) Since the positioning groove 16 is provided in the joint 10, the case 31 can be easily and quickly positioned with respect to the joint 10 by locking the projection 31A of the case 31 in the positioning groove 16. .

2) Since the case 31 is structured to be positioned by the positioning groove 16, the mounting surface 10 of the joint 10
It is not necessary to provide a convex portion or the like as a locking portion in B, and interference with the base member 32 and interference with the tip portion of the beam welding machine which may occur by providing such a portion are eliminated. Can be prevented.

3) The positioning groove 16 is provided with the pressure detecting element 20
Is provided around the tapered surface 15 which is a welded portion of the joint 10, stress generated when the joint 10 is bolted through the flange 40 is applied to the bottom of the positioning groove 16, that is, a portion which is separated downward from the tapered surface 15. You can focus. Therefore, the stress can be hardly applied to the diaphragm 21 of the pressure detecting element 20, and the output value shift can be prevented by preventing the diaphragm 21 from being distorted.

4) Since the bottom of the positioning groove 16 is provided with a recess, the stress can be concentrated on the recessed portion. Therefore, positioning groove 1
Even when the depth of the joint 6 cannot be increased, the stress is hardly applied to the welded portion, so that the output value shift of the pressure detecting element 20 can be reliably prevented, and the joint 10 can be made thinner.

[Second Embodiment] FIG. 2 is a sectional view showing a pressure sensor 2 according to a second embodiment. In the pressure sensor 2, a point corresponding to the flange 140 shown in FIG. 1 is formed by a separate flange 40, and the thickness of the flange 40 is thicker than the flange 140. The positioning groove 16 is different from the first embodiment in that the positioning groove 16 is provided in a simple vertical groove shape and the bottom side is not hollowed in the horizontal direction.

According to the present embodiment, since the positioning groove 16 is provided as in the first embodiment, the above-described 1)
To 3) can be obtained. In addition, the following effects are obtained by the specific configuration of the pressure sensor 2. 5) Since the joint 10 is bolted through the separate flange 40, a part of the stress generated by the tightening can be absorbed at the boundary between the joint 10 and the flange 40, and the joint 10 Can be reduced.

It should be noted that the present invention is not limited to the above embodiments, but includes other configurations that can achieve the object of the present invention, and the following modifications are also included in the present invention. For example, in the first embodiment, the bottom side of the positioning groove 16 is hollowed toward the center of the pressure introduction hole 11, but the bottom side is hollowed out in a direction away from the center of the pressure introduction hole 11, or in both directions. It may be gouged,
Even in these cases, the effects 1) to 4) described above can be obtained similarly. In which direction, the direction of the gouging may be determined as appropriate in the implementation.

Further, the bottom portion of such a positioning groove may be formed with a curved surface. By doing so, stress concentrated on the corners and the like in the positioning groove is dispersed. And the occurrence of cracks and the like in the groove can be reliably prevented.

In each of the above embodiments, the engaging portion provided on the joint is an annular groove. However, the engaging portion according to the present invention may be a plurality of concave recesses provided independently of each other. . In such a case, the case may be provided with projections corresponding to the depressions, and by locking the projections in the depressions, the above-mentioned effect 1) can be obtained.

In addition, the locking portion may be a step portion 116 as shown in FIG.
The object of the present invention can be achieved by locking the peripheral edge of the bottom opening of the case 31 to the step portion 116. However, if the stepped portion 116 is provided, it may easily interfere with the base member 32 or the tip of the welding machine depending on its size or dimensional error, and it is difficult to obtain the above-mentioned effect 2).
Since the stress at the time of tightening may be generated also in the step portion 116, a part of the stress affects the diaphragm 21 which is not so far from the step portion 116, and the effects of 3) and 4) described above. May be difficult to obtain.

Instead of providing the step portion 116, the diameter of the pedestal portion on which the pressure detecting element 20 is mounted (the portion whose upper surface is the tapered surface 15) is positively provided larger than the pressure detecting element 20 ( The bottom opening peripheral edge of the case 31 may be fitted to the outer peripheral surface of the pedestal portion, and the outer peripheral surface may be the locking portion of the present invention. However, also in this case, it may be difficult to obtain the effects 2) to 4) as described above.

In the above-described embodiment, the pressure sensor 1 is fastened to the installation portion A by inserting the bolt C into the flange 40 or the flange portion 140.
A female screw may be engraved on the inner peripheral surface of the insertion hole B, and a male screw corresponding to the female screw may be engraved around the pressure introducing hole 11, and the pressure sensor itself may be rotated and fastened. Even in such a case, the effect of the stress generated at the time of fastening by the action of the positioning groove 16 can be applied to the pressure detecting element 2.
In addition, the size can be reduced to zero, and the size and the like can be realized by eliminating the need for a flange or a flange portion.

In each of the above embodiments, the pressure sensor 1 for on-vehicle use and detecting the oil pressure is shown. However, the pressure sensor of the present invention is not limited to this. The present invention can be applied to any other devices, and can be applied to pressure detection of any fluid such as air pressure and water pressure.

[0038]

As described above, according to the present invention,
Since the joint is provided with the locking portion, the case can be easily positioned by locking the case to the locking portion.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pressure sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a pressure sensor according to a second embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a modification of the present invention.

FIG. 4 is a cross-sectional view showing the prior art of the present invention.

[Explanation of symbols]

 1, 2 Pressure sensor 10 Joint 10B Mounting surface 11 Pressure introduction hole 15 Tapered surface serving as welding portion 16 Positioning groove serving as locking portion 20 Pressure detecting element 31 Case 50 Electronic circuit component 116 Step portion serving as other locking portion

Claims (4)

[Claims] 1. A pressure detecting element welded to one end of a pressure introducing hole provided in a joint, and an electromagnetic circuit attached to the joint so as to surround an electronic circuit component electrically connected to the pressure detecting element. A pressure sensor comprising a shielding case, wherein the joint is provided with a locking portion for locking and positioning the case. 2. The pressure sensor according to claim 1, wherein
The pressure sensor according to claim 1, wherein the locking portion is provided in a substantially concave cross section depressed with respect to a mounting surface of the case, and the case is provided with a protrusion for locking with the locking portion. 3. The pressure sensor according to claim 2, wherein
The joint is fastened to a portion to be installed, and the locking portion having a concave cross section is an annular groove provided around a welding portion to which the pressure detecting element is welded. Pressure sensor. 4. The pressure sensor according to claim 3, wherein
The pressure sensor according to claim 1, wherein a depth side of the groove in the depth direction is provided so as to be hollowed along a radial direction of the pressure introduction hole.