JPS60201231A - Pressure detector of internal-combustion engine - Google Patents

Abstract

PURPOSE:To decrease the influence of temp. by inserting a pressure detector in the groove of a housing base surface, and holding said detector while it is pressed by a diaphragm. CONSTITUTION:The pressure detector composed of a heat insulator 63, a terminal 64, a pressure sensitive element 65 and a lead wire 61 is made in one body before being inserted into a housing groove 43 provided at a housing base surface 41 of a plug housing 4. Thereafter, said detector is held at the surface 41 so as to be pressed by the diaphragm 62 fixed by welding.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a pressure detector installed in various devices attached to the cylinder head of an internal combustion engine, such as spark plugs, glow plugs, injection nozzles, etc. This invention relates to a pressure detector that detects the pressure inside the combustion chamber of an engine.

[Prior art]

Conventionally, there is a pressure detector for detecting the pressure inside the combustion chamber of an internal combustion engine, for example, one described in Japanese Utility Model Application Publication No. 57-28351. A pressure-sensitive element is installed on the inner surface of the ring-shaped gasket provided under the surface (=I) to directly measure the pressure inside the cylinder. Since the 9th grade was directly exposed to the extremely hot gas inside the cylinder, the pressure detection section was significantly affected by deterioration and thermal distortion.

For this purpose, a groove is formed in the housing seat surface of the spark plug, the pressure sensitive element is insulated with a heat insulator, and the pressure sensitive element is placed in the same area so that it does not receive heat directly. In order to increase output, pressure-sensitive elements are stacked in layers.

However, stacking and assembling pressure sensitive elements, heat insulators, etc. has problems such as poor alignment of output holes and poor workability during assembly.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and includes a pressure sensor in which a pressure sensor, a pressure sensitive element, a terminal, and a heat insulator are integrally molded, is inserted into a groove formed in the seat surface of the housing of an instrument, and is pressed by a diaphragm. By holding the sensor, there is no breakage of the lead wire during installation, reducing the effect on acceleration sensitivity, making it easy to assemble and creating a structure that is difficult to break, and preventing temperature effects on the pressure-sensitive element due to combustion gas. It is an object of the present invention to provide a pressure sensor for an internal combustion engine having a heat insulating structure with reduced pressure.

[Structure of the invention]

In order to achieve the above object, the pressure sensor for an internal combustion engine of the present invention has a groove formed in the housing seating surface of an instrument attached to the cylinder head of the internal combustion engine, and is installed in the groove to measure the pressure inside the cylinder. In the pressure sensor for an internal combustion engine, the pressure sensor is formed by integrally molding a pressure sensing element, a terminal, and a heat insulator, and the pressure sensor is inserted into the groove and fixed to the housing seating surface. It is characterized by being held in a pressed manner by a diaphragm.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes a spark plug which is an instrument as an embodiment of the present invention, including a center electrode 2, an insulator 3 made of alumina, a caulking ring 13 made of a thin steel plate,
It is composed of an airtight backing 14 and a plug housing 4 made of copper, and the insulator 3 and the plug housing 4 are kept airtight by the crimping ring 13 and the airtight backing 14. The spark plug 1 is attached to the cylinder head 8 of an internal combustion engine using an airtight gasket 5, typically made of a copper washer or thin-walled steel plate, and
Threaded portion 11 such that its tip is located within combustion chamber 10
Attached by screwing. At that time, a pressure chamber 7 is formed by the housing seating surface 41 of the plug housing 4, the cylinder head 8, and the airtight gasket 5, and the pressure chamber 7 is located in the combustion chamber 10 in the pocket between the insulator 3 and the plug housing 4. 9, communicates via a pressure introduction hole 44 and a narrow groove 42 provided in the plug housing 4.

In the above-described 414 configuration, the pressure detector 6 includes a housing in which a heat insulator 63, a terminal 64, a pressure sensitive element 65, and a lead wire 61 are provided on the housing seating surface 41 of the plug housing 4, as shown in the cross-sectional view of FIG. Before being inserted into the groove 43, a diaphragm 62 is integrated with the sea urchin and is fixed by welding to the housing seating surface 41 so as to press it after being inserted.
is held by.

Here, the heat insulator 63 is shown in FIG.
As shown in (b), it is made of an insulator made of an inorganic material such as alumina, and a relief portion 632 for the terminal 64 is formed in a part thereof. In addition, the terminal 64 may be made of a metal with a low swelling coefficient similar to 1i511i coefficient, such as glass or ceramic.
For example, metals such as Kovar and Dumet wire,
As shown in the figure, the terminal part 641 and the retaining structure part 6
42, the locking structure part 642 is fitted to the relief part 632 of the terminal 64, and if the locking structure part 642 is to be stopped, it can be formed by flattening a part of the terminal part with a header or the like. Alternatively, it may be folded. Furthermore, the pressure sensitive element 65 is made of a piezoelectric material, and as shown in FIGS. 6(a), (b), and (c),
The electrode A, 8654.652, is fixed to the A, 8th side of the piezoelectric body 651 in FIG. Polarization occurs between electrode A 654 and electrode B 652. Electrode A 654 is connected to the plug housing 4 on the ground side, and electrode B 652 is connected to the terminal 64 on the output side.
It is connected to the.

The method for integrally molding the individual components such as the heat insulator 63, terminal 64, and pressure sensitive element 65 as described above is carried out as follows. That is, first, the low melting point glass 66 is coated on at least one of the output side of the pressure sensitive element 65 or the surface of the heat insulator 63 where the relief portion 632 is located by screen printing or the like. The part to be painted is the entire surface, a part other than the output electrode B652, or a part other than the part corresponding to the output electrode B652. A small amount of conductive metal paste 67 is filled in the escape portion 632 of the heat insulator 63 to improve conductivity, or the structure 64 to prevent the terminal 64 from being pulled out is filled.
2 is coated with metal paste 67. In the above condition,
The terminal portion 641 of the terminal 64 is passed through the through hole 653 of the pressure sensitive element 65, and the pull-out prevention structure portion 642 of the terminal 64 and the relief portion 632 of the heat insulator 63 are stacked thereon. Thereafter, the pressure sensitive element 65 and the heat insulator 63 are fired in an electric furnace with a load applied to them, and are integrally formed. that time,
If the firing temperature requires a temperature higher than one point at which the piezoelectric property of the piezoelectric body disappears, a voltage is applied between the electrodes A and 8654 and 652 of the piezoelectric body 651 after firing.
do.

Furthermore, the pressure detector 6 integrally molded as described above is
Terminal section 64 of terminal 64 as shown in FIG.
1 and the conductor portion 611 of the lead 161 are joined by means such as welding, and the joined portion is covered with the insulating portion 612 of the lead wire 61. The pressure detector 6 completed in this way is inserted into the housing groove 43 as shown in FIG.
, Dayaphram 6 with pro 22 as shown in (b)
2 is fixed to the housing seat surface 41 by welding at a welding rib 621, and is held by pressing with the rib 622 and applying a preload by striking. The lead wire 61 is passed through the lead hole 44 of the plug housing 4, brought into the housing 4, and passed through the pipe 4 fixed by means such as welding.
There, it is fixed by caulking or the like, led out from inside the housing 4, and the connector 66 is connected to the end thereof.

In the pressure detector for an internal combustion engine having the above configuration, the combustion chamber 1
0 pressure is guided from the plug pocket 9 to the pressure chamber 7 through the pressure introduction hole 44 and the narrow groove 42. guided combustion chamber 1
The pressure within 0 is applied to the diaphragm 62 of the pressure detector 6, and is applied as a force to the pressure sensitive element 65 via the heat insulator 63 and the terminal 64. When the pressure sensitive element 65 generates a charge due to the applied force, it is transmitted to the lead wire 61 via the electrode B 652 and the terminal 64. that time,
The heat insulator 63, the terminal 64, and the pressure sensitive element 65 are integrally molded, and the diaphragm 62 applies a preload to the heat insulator 63, the terminal 64, and the pressure sensitive element 65. Insulator 6
3, and there is no backlash due to vibration etc. In addition, since they are integrally molded, they complement each other in strength and are less likely to break.

Furthermore, since it has a heat insulator 63,
The heat applied to the diaphragm 62 is hardly transmitted to the pressure sensitive element 65, and is transmitted to the plug housing 4 through the diaphragm 62, so that the heat load on the pressure sensitive element 65 is light. Since the pressure detector 6 is formed integrally with the spark plug 1 in a small space, the mass of the spark plug 1 does not act as acceleration, resulting in good sensitivity, and the lead wire 6
Since spark plug 1 is used directly from spark plug 1, it does not get in the way when installed, and there is no possibility of disconnection. Furthermore, since there is no need to increase the diameter of the plug housing seating surface 41, there is no need to process the cylinder head 8 of the internal combustion engine to enlarge the part for installing the spark plug 1.

Note that in the above embodiment, the lead wire 61 was connected to the terminal 64 before being inserted into the plug housing groove 43, but the wire 64 was connected to the terminal 64 before being inserted into the plug housing groove 43 after the long diameter portion 642 of the terminal 6A was lengthened. Afterwards, it is also possible to join outside the plug housing 4. However, in that case, it is necessary to provide a separate insulator instead of using the insulator 612 of the lead wire 61. Further, although the case where the pressure sensor of the internal combustion engine is provided in a spark plug has been described, it goes without saying that the same structure and function can be applied to other devices such as glow plugs and injection nozzles.

(Effects of the Invention) As described above, in the pressure detector for an internal combustion engine according to the present invention, a groove is formed in the housing seating surface of the instrument to be attached to the cylinder head, and a pressure-sensitive element and a terminal are installed in the groove. A pressure detector with an integrally molded insulator is inserted and held by the diaphragm fixed to the housing seating surface, so the heat applied to the diaphragm by the combustion gas led to the pressure chamber is reduced due to the presence of the heat insulator. Since the heat is not easily transmitted to the pressure-sensitive element and is transmitted to the instrument housing, the heat load on the pressure-sensitive element is light and the influence of temperature is reduced.Also, since the pressure sensor is installed in the groove of the instrument housing, The output terminal can be taken out directly from the instrument housing, making it easier to wear, less susceptible to breakage of lead wires and changes in acceleration, and improving sensitivity.

Furthermore, since the pressure sensor is integrally molded, there is no need to align the terminal take-out hole compared to the conventional method of simply laminating and assembling, making assembly work easier. At the same time, the pressure sensor itself is reinforced by a heat insulator or pressure-sensitive elements, so it has the advantage of being less likely to break.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a spark plug, which is a device according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the main part of Fig. 1, and Fig. 3 is an integrally molded pressure plug in an embodiment of the present invention. 4 shows a heat insulator in the pressure detector of the present invention, FIG. 4 (A) is a sectional view, FIG. 4 (B) is a plan view, and FIG. A perspective view of the terminal in the detector, FIG. 6 shows the piezoelectric element in the pressure detector of the present invention, FIG. 6 (A) is a plan view of the 8th side of the piezoelectric element, and FIG. 6 (B) is a cross-sectional view. , FIG. 6(c) is a plan view of the A side of the piezoelectric element, FIG. 7 is a diaphragm in the pressure detector of the present invention, FIG. 7(a) is a cross-sectional view, and FIG. 7(b) is a plan view of the A side of the piezoelectric element. is a plan view. 1... Spark plug (appliance), 4... Housing, 4
1... Housing seating surface, 43... Annular groove, 6...
・Pressure detector, 62...Diaphragm, 63...Heat insulator, 64...Terminal, 65...Pressure sensitive element, 622...
...Rib, 66...Low melting point glass, 67...Metal paste. Agent Hiro Asamura Figure 1 Figure 2 Figure 4 (A) Figure 4 (B) Figure 5 Figure 6 (A) Figure 6 (0) Figure 6 (C) Figure 7 (B) Figure 7 (b)

Claims (1)

[Claims] 1. A groove is formed in the housing seating surface of a device to be attached to the cylinder head of an internal combustion engine, and a groove is provided within the housing,
In a pressure sensor for an internal combustion engine configured to detect internal cylinder pressure, the pressure sensor is formed by integrally molding a pressure sensing element, a terminal, and a heat insulator, and is inserted into the groove and mounted on the housing seat. A pressure detector for an internal combustion engine, characterized in that it is held in a pressed manner by a diaphragm fixed to a surface. 2. The internal combustion device according to claim 1, wherein the pressure detector is integrally formed with an adhesive using glass or a metal paste containing glass.
lIl pressure detector. 3. The internal combustion sensor according to claim 1, wherein the pressure sensor is provided with a pull-out prevention structure in a part of the terminal, and a heat insulator, and these are integrally molded. lll1] pressure sensor.