JPH0544152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spark plug used in an automobile internal combustion engine, and more particularly to a spark plug with a built-in pressure sensor, and more particularly to an improvement in a connection part for extracting a signal from a pressure sensor.

Conventionally, the connection part of a spark plug with a built-in pressure detector was
For example, as described in Japanese Patent Application Laid-Open No. 57-40887,
The signal from the pressure detector is taken directly to the outside of the spark plug housing via a lead wire, and a terminal is provided at the tip of the lead wire, or the housing is provided with a groove and a thin plate-like terminal is taken out through the groove. be.

However, if the lead wire is taken out directly to the outside of the spark plug housing as in the former case, the lead wire and the terminal portion will get in the way when the pressure detector built-in spark plug is installed in the cylinder portion of the internal combustion engine.

In addition, if a groove is provided in the ignition housing and the terminal is taken out through the groove as in the latter case, the connector section connected to the terminal will be installed inside the rubber jacket of the high voltage cord cap section, and the ignition plug with a built-in pressure sensor will be installed. It is easier to install in an internal combustion engine, and accidents such as disconnection due to vibration during use can be prevented, but when installing the rubber jacket of the plug cap, it is necessary to align it with the terminal, and the hexagonal part of the housing is large. As a result, the outer diameter of the cap rubber jacket is larger than that for general spark plugs, which is disadvantageous in that additional work such as enlarging the spark plug insertion recess in the cylinder section is required.

The present invention has been made to solve the above-mentioned disadvantages, and an object of the present invention is to provide a spark plug with a built-in pressure sensor that is small, easy to install in an internal combustion engine, and compatible with general spark plugs. It is.

In order to achieve the above object, a spark plug with a built-in pressure sensor of the present invention has an insulator with a built-in center electrode, and is equipped with a pressure sensor for detecting the pressure in the combustion chamber of an internal combustion engine, A ring-shaped terminal is fixed to the head so as to transmit the signal of the pressure sensor, and the connection part of the terminal is in a rubber cap that integrally covers the area from the spark plug high-pressure cord to the top surface of the hexagonal part of the spark plug housing. It is characterized by being installed so that it touches the terminal.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the spark plug 1 includes a metal housing 3 having a threaded portion 33 to be screwed into the cylinder head of an internal combustion engine, an insulator 2 such as an insulator housed within the housing 3, A center electrode 15 insulated from the housing 3 by the insulator 2, a ground electrode 16 provided at the lower end of the housing 3 and facing the center electrode 15, and the housing 3 and the insulator 2.
It is composed of an airtight packing 14 and a caulking ring 13 for airtightly fixing the parts. Further, the housing 3 is provided with a hexagonal part 11 that serves as a plug wrench fitting part when screwed onto the cylinder head of an internal combustion engine, and the housing seat surface 35 that comes into contact with the cylinder head when screwed onto the cylinder head has a hexagonal part 11. An annular groove 34 is provided, and a pressure sensor 4 made of, for example, a piezoelectric element formed in an annular shape is installed in the annular groove 34,
It is fixed by welding a diaphragm 41 made of an annular thin metal plate. A pressure introduction hole 31 and a pressure introduction groove 32 following the pressure introduction hole 31 are formed in the threaded portion 33 of the housing 3 in order to guide the combustion chamber pressure of an internal combustion engine (not shown) to the pressure detector 4. The combustion chamber pressure of the internal combustion engine is transmitted to the pressure diaphragm 41 via the pressure introduction hole 31 and the pressure introduction groove 32, and thereby the pressure detector 4
emits an electrical signal.

The connection part that takes out the signal from the pressure detector 4 is
It consists of an output lead wire 5 from the pressure detector 4 and a terminal 6 fixed to the outer periphery of the head of the insulator 2. The output lead wire 5 is coated with a heat-resistant insulating material such as Teflon, and has a lead hole 36 that extends from an annular groove 34 provided in the housing 3 toward an inner diameter hole in which the insulator 2 is housed, and a large diameter hole of the insulator 2. It is connected to the terminal 6 by soldering or the like through a lead groove 21 provided in the section. Terminal 6 is shown in Figure 2 A,
As shown in FIG. 2, it is formed into a ring shape with one end open, and is fitted and fixed in a groove 22 provided on the outer circumference of the head of the insulator 2.

The connection part of the above terminal 6 is the high voltage cord 17
A metal tube 7 is provided in a rubber cap 9 that integrally covers the upper surface of the hexagonal portion 11 of the housing 3, and is tightly fitted to the outer circumferential portion of the terminal 6. The high-voltage cord 17 is provided in the rubber cap 9 so as to be in close contact with a metal tube 10 fitted into a spark plug terminal portion 16 protruding from the end of the insulator 2. Further, a lead wire 8 is connected to a metal tube 7 provided within the rubber cap 9 so as to take out a signal to the outside. As described above, the rubber cap 9 is connected to the connection part of the terminal 6, the lead wire 5, and the groove 21 for the lead wire 5 of the insulator 2.
Prevents water and dust from entering.

The pressure detector built-in spark plug 1 of the above embodiment has an insulator 2 with a built-in center electrode 15, and a pressure detector 4 is annularly provided on a metal spark plug housing seat 35 that holds the insulator 2. , a ring-shaped terminal 6 fixed to the head of the insulator 2 to transmit the output signal of the pressure detector 4 is provided, and a connection portion of the terminal 6 is connected from the spark plug high voltage cord 17 to the spark plug housing 3. Since the terminal 6 is installed in the rubber cap 9 which integrally covers up to the upper surface of the hexagonal part 11 of the terminal 6, the following results can be obtained.

(1) When installing the spark plug 1 into the cylinder head of an internal combustion engine, unlike conventional spark plugs with built-in pressure detectors, lead wires and terminals are not provided outside, so there are no obstacles in the way. It can be easily and quickly screwed on like a general spark plug.

(2) The terminal 6 is made of a thin metal plate formed into a ring shape, and the connection part is also a metal tube 7 installed inside the rubber cap 9.
There is no need for special alignment, and the installation can be done easily and reliably.

(3) Rubber cap 9 connects terminal 6, connection part,
Since all exposed parts of the spark plug 1 such as the lead wire 5 and the lead groove 21 provided in the insulator 2 are covered, water, dust, etc. can be completely prevented from entering the main parts of the pressure detector 4. I can do it.

In the above embodiment, the terminal 6 was shaped to fit into the groove 22 of the insulator 2, but as shown in FIG. You may also do so.

In the above embodiment, the pressure detector 4 is of the type that operates by directly receiving the pressure inside the cylinder, but the pressure detector 4 may be of the type that operates by detecting changes in the pressure applied to the component parts. Similar effects can be obtained by installing the spark plug in a ring shape in the spark plug gasket, or in an annular space between the insulator and the housing.

As described above, the spark plug with a built-in pressure detector according to the present invention has a connection part for taking out a signal from the pressure detector inside the rubber cap so as to make contact with the terminal provided on the head of the insulator, so it can be made smaller. It has the excellent effects of being easy to install in an internal combustion engine and being compatible with general spark plugs.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a spark plug with a built-in pressure sensor which is an embodiment of the present invention, Fig. 2 shows a terminal used in the spark plug of Fig. 1, and Fig. 2A is a plan view of the terminal. FIG. 2B is a sectional view, and FIG. 3 is a sectional view of main parts showing another embodiment of the terminal. 1... Spark plug, 2... Insulator, 3... Housing, 4... Pressure detector, 6... Terminal,
9...Rubber cap, 11...Hexagonal part, 15...
Center electrode, 35...Housing seating surface.

Claims (1)

[Claims] 1. An annular shape having an insulator with a built-in center electrode and a pressure detector for detecting the pressure in the combustion chamber of an internal combustion engine, and fixed to the head of the insulator so as to transmit an output signal of the pressure detector. A pressure detector characterized in that the connection part of the terminal is installed in a rubber cap that integrally covers from the spark plug high voltage cord to the top surface of the hexagonal part of the spark plug housing so as to be in contact with the terminal. Built-in spark plug.