JPH0265084A - Pressure sensor-built-in spark plug - Google Patents

Abstract

PURPOSE:To fix a main metal and assure the contact between a pressure sensor and a conductor over a long period by pressure-connecting an elastic terminal extracted from the electrode plate of the built-in pressure sensor to the metal paste conductor sintered on the surface of an insulator and driving wedges. CONSTITUTION:A pressure sensor 5 is constituted by pinching an electrode plate 7 made of a spring material with two piezoelectric elements 8. A pair of wedges 9 with inclined faces in opposite directions are driven in a storing groove 10 provided on the barrel section 4 of a main metal 3, thereby the pressure sensor is fixed in the storing groove 10. A terminal 12 extracted from the electrode plate 7 toward an insulator 2 is sintered on the surface of the insulator 2 while being insulated from the main metal 3 by the insulator 2, and it is pressed and fixed and connected to the metal paste 13 face conductive to an electrode terminal 6 provided around the insulator 2. The connection between the metal paste 13 sintered on the surface of the insulator and the electrode plate 7 can be assured over a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a spark plug with a built-in pressure sensor used in an internal combustion engine.

(Prior art) Conventionally, in spark plugs with a built-in pressure sensor used in internal combustion engines, the pressure sensor is a piezoelectric element covered with an insulating material that is press-fitted into a hole drilled in the body of the metal shell and fixed. , a signal detected from the piezoelectric element is transmitted to a CPU or the like through a lead wire.

(Problem to be Solved by the Invention) However, in the above conventional device, a piezoelectric element covered with an insulating material is press-fitted and fixed into a hole drilled in the body of the metal shell, and the piezoelectric element is detected from the piezoelectric element. In the case where signals are transmitted to the CPtJ etc. by lead wires, the lead wires that transmit the signals detected by the piezoelectric element to the CPU are drawn out from above the metal shell. It is susceptible to deterioration due to heat and has the disadvantage of being prone to damage such as poor contact and disconnection.

In order to improve this drawback, it has been proposed to sinter metal paste on the surface of an insulator instead of the lead wire to form a conductor, and to extract signals from electrode terminals provided around the surface of the insulator. However, since the contact between the piezoelectric element and the electrode plate sandwiched between the piezoelectric elements is not performed while applying mechanical stress, there is a problem that the contact is not reliable. Therefore, the present invention aims to improve the above-mentioned drawbacks of the conventional method, and aims to ensure a long-term connection between the metal paste sintered on the surface of the insulator and the electrode plate.

(Means for solving the problem) To this end, an electrode plate made of a spring material and a pressure sensor made of a piezoelectric element are fixed to the body of the metal shell with a pair of wedges, and the electrode plate is pulled out from the electrode plate toward the insulator. The terminal is insulated from the metal shell and is crimped onto a conductor formed by sintering a metal paste on the surface of the insulator.

(Function) With the above configuration, the pressure sensor consisting of a spring electrode plate and a piezoelectric element is fixed in the vertical direction by driving a wedge into the body of the metal shell, and the pressure sensor is pulled out toward the insulator of the plug. An elastic terminal connected to the electrode plate is insulated from the metal shell by an insulator, pressed against the radial direction of the spark plug, and crimped and fixed to a conductor made of metal paste sintered on the surface of the insulator. The connection can be secured over a long period of time.

(Example) This invention will be further explained with reference to an example shown in the drawings. (1) is a spark plug with a built-in pressure sensor which is an example of the present invention.
) is an insulator (2) that surrounds a pressure sensor (5) built into the body (4) of the metal shell (3) and an electrode terminal (6) for taking out a signal from the pressure sensor (5); It is composed of threaded parts (1, 4) provided at the tip of the metal shell (3), a center electrode (15), an outer electrode (16), etc. The pressure sensor (5) is mounted on a spring. An electrode plate (7) made of a material is sandwiched between two piezoelectric elements (8), and the two piezoelectric elements (8) are placed in a housing groove (10) provided in the body (4) of the metal shell (3) in directions facing each other. By driving a pair of wedges (9) (9) with inclined surfaces into the
A pressure sensor is fixed in the housing groove (10), and the terminal (12) drawn out from the electrode plate (7) toward the insulator (2>) is connected to the metal shell (3) by the insulator (12).
The metal paste (13) is sintered onto the surface of the insulator (2) and is electrically connected to the electrode terminal (6) provided around the insulator (2) while being insulated from the insulator (2). It is something. Furthermore, the connection between the metal paste (13) and the terminal (11) drawn out from the electrode plate (7) is made using wedges (9) having inclined surfaces facing each other in order to fix the piezoelectric element (8). By driving (9), a force (F) acting in the vertical direction is generated, and the vertical direction is fixed,
The inward force (f) causes the terminal to be crimped (Fig. 4), and the terminal (1
1) The elastic contact with the conductor (13) ensures reliable electrical connection. In addition, an insulating material (11) such as rubber for electrical insulation is placed around the electrode plate (7).
), the insulation between the metal shell (3) and the metal shell (3) is sufficient, and electrical interference with the metal shell (3) can be prevented.

(Effects of the Invention) As described above, the elastic terminal drawn out from the electrode plate of the built-in pressure sensor is crimped to the conductor made of metal paste sintered on the surface of the insulator, and a wedge is driven into the main body. The metal fittings can be fixed, and it has a simpler structure than conventional ones, which improves reliability and eliminates lead wires, making it easier to handle when storing.
Furthermore, contact between the pressure sensor and the conductor can be permanently ensured.

It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a spark plug with a built-in pressure sensor, which is an embodiment of the present invention, and FIGS. A sectional view is shown, and FIG. 4 is an exploded perspective view showing the configuration of the pressure sensor. 1... Spark plug with built-in pressure sensor 2... Insulator 3... Metal shell 4... Body 5... Pressure sensor 6... Electrode terminal... Wedge 2... Competitive connection Of course 7...Electrode plate 8...Piezoelectric element 0...Accommodating groove 1...1 conductor made of terminal metal paste

Claims (1)

[Claims] An electrode plate made of a spring material and a pressure sensor made of a piezoelectric element are fixed to the body of the metal shell with a pair of wedges, and an elastic terminal drawn out from the electrode plate toward the insulator is inserted through the insulator. A spark plug with a built-in pressure sensor that is insulated from the main metal fitting and crimped onto a conductive body formed by sintering metal paste on the surface of the insulator.