JPS62215838A - Pressure sensor - Google Patents

Abstract

PURPOSE:To make it possible to prevent the leakage of a liquid between both ends of a joint and an integrated body, by almost wrapping the integrated body by a metal outer skin and positioning the joint thereof on a surface to be pressurized. CONSTITUTION:Ring-shaped piezoelectric elements 2, 2 are stacked through a conductive plate 3 and a ring-shaped press metal 4 comprising a metal of low coefficient of expansion is arranged to the under surface thereof to constitute an integrated body 1 which is, in turn, wrapped in a metal outer skin 5 by drawing processing and the joint 6 thereof is positioned on the surfaces (y), (y) to be pressurized contacted with press bodies (x), (x) such as cylinder heads or plugs. Further, a lead wire 7 covered with a metal jacket is inserted in the metal outer skin 5 from the notch part formed to a part thereof and the core wire 8 of the lead wire 7 is connected to the conductive plate 3 to constitute a ring-shaped pressure sensor.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pressure sensor that is held on the surface of a vibrating body such as a cylinder head of an engine that generates vibrations due to knocking or fuel injection, and detects pressure fluctuations using a piezoelectric element. Regarding.

<Prior art> This type of pressure sensor is held on the surface of a vibrating body by tightening an appropriate screw body, such as by inserting it between the gasket seat surface of an engine spark plug and the plug seat of a cylinder head, and is held on the surface of a vibrating body by tightening an appropriate screw body. This produces compressive strain in the piezoelectric element, and an output signal synchronized with the vibration is extracted from the piezoelectric element, and as described above, when applied to a cylinder head, it is used to detect knocking and fuel injection timing.

As this conventional pressure sensor, as shown in Fig. 6,
Some devices are made by covering an integrated body consisting of a piezoelectric element, a presser foot, etc. stacked together with a metal outer cover.

Such a conventional device stacks two piezoelectric elements a and a with electrode plates interposed therebetween, and further includes a low expansion coefficient metal such as Invar, Kovar, 42Ni-Fe, etc., with a caulking portion d projecting upward on the L thereof. A presser foot C having an inverted T-shaped cross section made of material 1 is mounted and covered with a metal shell e, and the presser foot C is caulked with the shoulder portions on both sides of the caulking portion 6. The tightening portion d is made to protrude upward.

<Problems to be Solved by the Invention> By the way, with the above configuration, the crimped portion d has the arrow line,
The tightening pressure of a threaded body such as a spark plug is applied as shown in FIG. Looseness f is likely to occur, and oil and
Water etc. enters and the inside of the metal outer skin e becomes damp, causing the piezoelectric element a.

There are drawbacks such as deterioration of a, electrical layer M, etc.

The present invention aims to eliminate such drawbacks.

Means for Solving the Problems> The present invention is characterized in that the metallic outer skin substantially surrounds the aggregate, and the joint thereof is located on the pressurized surface.

Effect> The clamping force from both the screw body and the vibrating body (hereinafter each collectively referred to as the pressurizing body X) is transmitted to the piezoelectric element via the metal outer skin. Therefore, since the joint portion is also tightened, looseness at the phantom joint and intrusion of liquid can be prevented as much as possible.

<Embodiment> FIG. 1.2 shows an embodiment of the present invention having the most basic configuration.

Annular piezoelectric elements 2.2 are stacked with conductive plates 3 interposed therebetween, and an annular presser foot 4 made of a low expansion coefficient metal is placed on the lower surface of the annular presser foot 4 to form an integrated body 1. It is wrapped in a made outer skin 5, and its joint 6 is subjected to the force of the cylinder head, plug, etc.■pressure body X, pressurized surface y in contact with X,
Position it at y. Further, as shown in FIG. 1, a lead wire 7 covered with a metal jacket is passed through the cutout part forming a part of the metal jacket 5, and the core wire 8 of the lead wire 7 and the conductive plate 3 are connected to each other. connected, thus forming an annular pressure sensor.
Incidentally, if necessary, a spacer 9 may be provided between the upper piezoelectric element 2 and the upper surface of the metal outer skin 5, as shown in FIGS. 3 to 5.

In the above structure, when pressure is applied to the upper and lower surfaces of the piezoelectric element 2.2 by the pressure bodies X, X, the pressure acts directly on the upper and lower surfaces of the outer skin 5 and is applied to the piezoelectric element 2.2 via the presser foot 4. For this reason, a voltage proportional to the pressure fluctuation is generated in the piezoelectric element 2.2 and is taken out from the conductive plate 3 via the core 1ffl 8 as an output signal.

3 to 5 relate to an embodiment in which the basic configuration is further improved. In other words, in the above structure, compared to the conventional structure, there is a slight reduction in the quality of wood and oil that occurs from the caulked end of the metal outer skin 5, but in the following embodiment, wood and oil are removed from the caulked edge. This provides even better leakage prevention.

FIG. 3 shows that fitting grooves 11 and 12 are formed on the inner and outer edges of the lower part of the presser foot 10 at the lower part of the piezoelectric element 2.
O-rings 13 and 14 made of a fluorine-based or silicone-based resin material are respectively fitted to the assembly 1 having such a structure.
is wrapped in a metal shell 5, and the connection [16] is placed at the lower surface of the presser foot 10. Here, a spacer 9 is provided between the upper piezoelectric element 2 and the upper surface of the metal outer skin 5. The assembly 1 is sealed within the metal shell 5 by caulking both ends of the metal shell 5 inward.

With this configuration, even if liquid enters between the joints 6, it is blocked by the O-ring 13.14, and the influence on the piezoelectric element 2.2 is eliminated.

Figure 4 shows the O-ring 1 in the fitting groove 11.12 of the presser foot lO.
3.14, and a plate packing 15 is placed below the presser foot 10 so as to cover the O-rings 13.14 as well. Pressure is applied to both ends of the plate packing 15, and the O-rings 13 and 14 are inserted into the fitting grooves IL,
12, the O-ring 13
．． The sealing effect by 14 becomes even better.

FIG. 5 shows a resin 21 such as fluorine-based resin 21
The end edge of the metal outer skin 5 is caulked and sunk into the resin 21. This improves the sealing performance, and the resin 21 prevents liquid from leaking from the joint 6.

<Effects of the Invention> The present invention provides piezoelectric elements 2, 2 . An assembly l formed by stacking presser feet 4, 10, 20, etc. is wrapped in a metal outer cover 5,
Since the pressure sensor is constructed by locating the joint 6 on the pressurized surfaces y, y in contact with the pressurizing body X, the clamping force of the pressurizing body X is directly received only by the metal outer skin 5, and the joint This has excellent effects such as preventing leakage of liquid from between both ends of the tube 6 and the assembly 1 as much as possible.

[Brief explanation of drawings]

The accompanying drawings show embodiments of the present invention; Fig. 1 is a longitudinal sectional side view of the first embodiment, Fig. 52 is an enlarged longitudinal sectional side view of the same part, and Fig. 3 is an enlarged longitudinal sectional view of a part of the second embodiment. A side view, FIG. 4 is an enlarged vertical side view of a part of the third embodiment, FIG. 5 is an enlarged longitudinal side view of a part of the fourth embodiment, and FIG. 6 is an enlarged longitudinal side view of a part of the conventional configuration. It is a diagram. l; integrated body 2, 2; piezoelectric element 4, 10.20; presser foot 45: metal outer cover 6; joint 11.12. Mating i+
W l 3, 14; O-ring 15, plate packing 21; Resin applicant NGK Spark Plug Co., Ltd. agent Patent attorney Kita Matsuura Younger brother 1 Figure 2 Figure 30 Foil 4

Claims (1)

[Scope of Claims] 1) A pressure sensor in which a piezoelectric element, a presser foot, etc. are piled up and the stack is covered with a metal outer cover, and the metal outer cover almost wraps the aggregate and covers the joints thereof. Pressure sensor characterized in that it is located on the pressurizing surface 2) A fitting groove is formed on the inner and outer edges of the lower part of the presser foot placed at the lowest part of the assembly, and a fluorine-based or silicone-based resin material is formed in the fitting groove. 2. The pressure sensor according to claim 1, further comprising an O-ring which is surrounded by a metal shell directly or through a plate packing. 3) A layer of fluorine-based resin or the like is formed on the lower surface of the presser foot disposed at the lowest part of the aggregate, and the resin layer is surrounded by the metal outer skin.
Pressure sensor as described in section.