JPH06265431A - Attaching method for cylinder inner pressure detecting device - Google Patents

Abstract

PURPOSE:To provide an attaching method for a gasket type cylinder inner pressure detecting device which can always accurately detect the fluctuation of clamping load along the fluctuation of combustion pressure in an engine cylinder. CONSTITUTION:A fitting section 4 between an attaching hole 21 drilledly provided on the cylinder head 2 of an engine and an attached member 3 to which a cylinder inner pressure detecting device 1 to be inserted into the attaching hole 21 is fixed is provided with an adhering mechanism 40 for fitting a heat resisting auanular variable material 42 in a groove 41 provided in the fitting section 4. On the other hand, a tapered part or a stepped part provided on the inner periphery of the attaching hole 21 at the tip of a threaded part threadedly attached in the fitting section 4 and a tapered part or a stepped part provided on the outer periphery of the attached member are pressed into contact with each other to form the adhering mechanism, and the cylinder inner pressure detecting device 1 is fixed to the cylinder head 2 by clamping nuts, and heat resistant sealing material is filled up in the fitting section 4 to form the adhering mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a gasket type in-cylinder pressure detecting device which is mounted on a cylinder head of an engine and detects a fluctuation in combustion pressure in the cylinder due to knocking or combustion by a piezoelectric element. is there.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional method for mounting an in-cylinder pressure detecting device. In the cylinder head 2 of the engine,
The mounting hole 21 for the spark plug is threaded, and this mounting hole 2
The metal shell 31 of the spark plug 3 is screwed into the inside of the screw 1 with a prescribed torque. Then, the pressure detecting device 1 is mounted on the outer periphery of the upper end portion of the outer peripheral threaded portion 32 of the metallic shell 31, and is mounted between the cylinder head 2 and the gasket 33 of the spark plug 3 by screwing the threaded portion 32 described above. Is known.

The pressure detecting device 1 comprises a piezoelectric element unit 10 and a sleeve 15. Piezoelectric element unit 10
Is a substantially U-shaped metal case, inside of which an annular plate-shaped piezoelectric element 11, 11 is provided with an annular electrode plate 13 with a lead wire 12, and the outer surface of the piezoelectric element 11, 11 is an annular shape. The front end surface of the metal case is bent inward so as to be sandwiched between the plate-like packings 14, 14. Around the outer circumference of the lead wire 12, a metal sleeve portion 1 for holding the insulation coating.
5 are provided.

[0004]

However, in the conventional method, what is detected by the in-cylinder pressure detecting device is the fluctuation of the tightening load with respect to the mounting portion of the spark plug 3 to the engine. The fluctuation of the tightening load of the spark plug 3 is
If the primary fluctuating load is the one in which the combustion gas generated by the combustion of the air-fuel mixture in the combustion chamber pushes the plug ignition part in the direction opposite to the tightening load direction, the screw part 32 of the metal shell 31 is assumed.
The combustion gas is combined with the secondary fluctuating load that pushes the mounting seat portion of the metallic shell 31 in the direction opposite to the tightening load direction of the spark plug 3 through the gap existing in When passing through the gap existing in the threaded portion 32 of the metallic shell 31, since the gap through which the combustion gas flows in and out is extremely small, resistance is generated due to the inflow and outflow of the combustion gas, and there is a delay in the detection of fluctuations. Occurs, and the synthetic action is also distorted.

FIGS. 8A and 8B show engine test results under the condition of 1000 rpm and 6% load in the conventional mounting method of the pressure detecting device 1. (A) is a comparison diagram of the engine output waveform of the acupressure gauge and the output waveform of the pressure detection device 1, (b)
Shows the correlation output waveform. In the correlation output waveform of (b) of FIG. 8, the distortion caused by the delay of the secondary variable load described above is observed between the acupressure meter and the pressure detection device 1. As described above, the conventional mounting method of the pressure detection device 1 has a drawback in that it is not possible to detect the variation of the tightening load of the spark plug 3 along with the variation of the combustion pressure.

The present invention solves the above-mentioned drawbacks of the prior art and is mounted on a metal shell seat portion of a spark plug or the like, which can accurately detect the fluctuation of the tightening load of the spark plug along with the fluctuation of the combustion pressure. The present invention provides a method for mounting a gasket-type cylinder pressure detecting device.

[0007]

According to a method for mounting a cylinder pressure detecting device of the present invention, a mounting hole formed in a cylinder head of an engine and a cylinder pressure detecting device inserted in the mounting hole are fixed. A fitting mechanism for blocking the invasion of combustion gas in the cylinder is provided at the fitting portion with the mounted object.

This contact mechanism comprises a heat-resistant annular variable material fitted in a groove provided in the fitting portion. Other,
The taper portion or step portion provided on the inner periphery of the mounting hole at the tip of the screw portion screwed at the fitting portion and the taper portion or step portion provided on the outer periphery of the mounted object are brought into pressure contact with each other to form the contact mechanism. The in-cylinder pressure detection device is fixed to the cylinder head with a tightening screw, or the fitting portion is filled with a heat-resistant sealing material to form a close contact mechanism.

[0009]

In the method of mounting the in-cylinder pressure detecting device of the present invention, since there is no gap between the mounting hole of the engine and the metal shell, the combustion gas generated in the combustion chamber tightens the spark plug ignition part in the direction of the load. Only the primary fluctuating load that pushes in the opposite direction is measured, and the influence of the secondary fluctuating load can be eliminated.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a method of mounting a cylinder pressure detecting device 1 according to a first embodiment of the present invention. The numbers in the figure are the same as those described above. A spark plug mounting hole 21 is formed in the cylinder head 2 of the engine.
Inside, the threaded portion 32 of the metal shell 31 of the spark plug 3
It has a screw portion 22 that is screwed. Also, the mounting hole 2
A fitting portion 4 is formed between the metal shell 1 and the metal shell 31, and a part of the fitting portion 4 is screwed by the screw portions 32 and 22 as described above. Then, on the cylinder head 2 side of the fitting portion 4,
An O-ring 41, which is a close contact mechanism 40, and an annular groove 42 into which the O-ring 41 is fitted are provided on the combustion chamber side of the screw portion 22.

The spark plug 3, which is a mounted object, has a metal shell 31 having an insulator 34 and a center electrode 35 therein.
Have. The metal shell 31 has a straight portion 36 with which the O-ring 41 abuts at its tip, the screw portion 32, and the body portion 3 having a large diameter.
7, a hexagonal head portion 38 is formed.

The pressure detecting device 1 is sandwiched between the cylinder head 2 of the engine and the plate-like gasket 33 of the spark plug 3 and fixed by screwing the screw portion 22 of the cylinder head 2 and the screw portion 32 of the metal shell 31. It Further, the pressure detection device 1 includes a piezoelectric element unit 10 including an annular plate piezoelectric element 11, an annular electrode plate 13 with a lead wire 12, and an annular plate packing 14, and a sleeve portion 15 on the outer circumference of the lead wire 12. And has the same structure as the conventional pressure detecting device.

The method of mounting the pressure detecting device 1 on the engine is as follows.
After the O-ring 41 is fitted into the groove 42 formed in the inner wall of No. 1, the threaded portion 22 of the cylinder head 2 and the threaded portion 32 of the metal shell 31 are screwed with a prescribed tightening torque. At this time, the O-ring 41, which is a variable material, has a function of deforming by tightening the fitting portion 4 to seal the cylinder head 2 and the metal shell 31, so that the combustion gas in the cylinder flows into the fitting portion 4. Prevent.

2 (a) and 2 (b) show the test results of the pressure detecting device 1 using the mounting method of the first embodiment, showing the test results under the condition of 1000 rpm of engine and 6% load. Show. (A) is a comparison diagram of the engine output waveform of the acupressure gauge and the output waveform of the pressure detection device 1, and (b) the correlation between the output from the pressure detection device 1 on the vertical axis and the output of the acupressure gauge on the horizontal axis. The output waveform is shown. As can be seen from this graph, the output from the pressure detection device 1 and the output from the acupressure meter show almost the same waveform, and the correlation output waveform also shows substantially the same value when the pressure increases and when the pressure decreases. Therefore, it can be understood that the mounting method of the pressure detecting device according to the present invention can accurately measure the fluctuation of the tightening load along with the pressure fluctuation in the cylinder.

In this embodiment, the groove 42 is formed in the mounting hole 21 of the cylinder head 2, but it is a variable material O.
The groove into which the ring 41 is fitted may be provided on the outer circumference of the metal shell 31, and in this case, the mounting hole 2 that abuts the O-ring 41.
The inner wall of 1 is a straight part.

FIG. 3A shows a method of mounting the cylinder pressure detecting device 1 according to the second embodiment of the present invention. In the mounting hole 21 of the cylinder head 2 of this embodiment, a taper portion 43 formed in an annular shape on the combustion chamber side from the screw portion 22.
Have. Further, similarly to the taper portion 43, an annular taper portion 44 is formed on the metal shell 31 of the spark plug 3 closer to the combustion chamber than the screw portion 32. The tapered portions 43 and 44 are the close contact mechanism 40 of the present invention, and have the same taper angle, and the two are closely pressed by screwing the hexagonal cylindrical portion 38 of the metal shell 31 into the mounting hole 21. .

In the method of mounting the cylinder pressure detecting device 1 of the present invention, first, the spark plug 3 is attached to the cylinder head 2.
Before being screwed into the mounting hole 21, the tightening nut 5 shown in FIG. 3B is screwed into the threaded portion 32 until it abuts the body portion 37. Then, the gasket 33 is attached to the mounting hole 21.
When the spark plug 3 having the pressure detecting device 1 mounted thereon is tightened with a predetermined torque, the taper portions 43 and 44 are pressed against each other, and the fitting portion 4 is brought into close contact. After that, the tightening nut 5 is tightened with a torque smaller than the tightening torque of the spark plug 3, and the gasket 33 and the pressure detection device 1 are sandwiched between the cylinder head 2 and the tightening nut 5 and fixed. The gasket 33 may be omitted.

The tightening nut 5 comprises a threaded portion 51 screwed into the threaded portion 32 of the metal shell 31 and a body portion 52. In this embodiment, the notch 5 is provided for easy tightening.
3 is provided.

4 (a) and 4 (b) show the test results of the pressure detecting device 1 using the mounting method of the second embodiment, showing the test results under the condition of 1000 rpm and 6% load of the engine. Show. (A) is a comparison diagram of the engine output waveform of the acupressure gauge and the output waveform of the pressure detection apparatus 1, and (B) shows the correlation output waveform of the pressure detection apparatus 1 and the acupressure gauge. Similar to the first embodiment, the output from the pressure detecting device 1 and the output from the acupressure meter show almost the same waveform from this graph as well, and the cylinder head 2 and the fitting portion 4 of the metal shell 31 are in close contact with each other. By doing so, it can be understood that the fluctuation of the tightening load along with the pressure fluctuation in the cylinder can be accurately measured.

FIG. 5 shows a method of mounting the cylinder pressure detecting device 1 according to the third embodiment of the present invention. At the tip of the mounting hole 21 of the cylinder head 2 of this embodiment on the combustion chamber side,
When the threaded portion 22 of the cylinder head 2 and the threaded portion 32 of the metal shell 31 are screwed together, the step portion 46 at the tip of the metal shell 31 has a step portion 46 of the nut 5. By tightening, the step portion 45 is brought into close contact with and abutted. Others are the same as those in the second embodiment. As a result, the fitting portion 4 is sealed and the combustion gas from the combustion chamber does not flow in, and only the gas pressure of the combustion gas flowing into the metal shell 31 can be detected as in the second embodiment.

FIG. 6 shows a mounting method of the cylinder pressure detecting device 1 according to the fourth embodiment of the present invention. At the tip of the mounting hole 21 of the cylinder head 2 of this embodiment on the combustion chamber side,
A silicon-based or polyamide-based adhesive 47, which is a heat-resistant sealing material, is attached, and the screw portion 22 of the cylinder head 2 and the screw portion 32 of the metal shell 31 are screwed together to form the contact mechanism 40. By this contact mechanism 40, the combustion gas from the combustion chamber does not flow into the fitting portion 4, and only the gas pressure of the combustion gas flowing into the metallic shell 51 can be detected. Further, in this embodiment, the spark plug 3 and the cylinder head 2 have the advantage that conventional ones can be used.

[0022]

According to the method of mounting the in-cylinder pressure detecting device of the present invention, since the fitting portion between the mounting hole of the cylinder head and the mounted object on which the pressure detecting device is mounted is sealed, the output of the pressure detecting device is reduced. It is possible to always detect an accurate change in the tightening load according to the pressure fluctuation in the cylinder without delay. Therefore, more accurate and high-level engine control can be performed based on the detected pressure data in the cylinder.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mounting method of a cylinder pressure detecting device of a first embodiment of the present invention.

FIG. 2 is a graph showing a pressure measurement result by the mounting method of the in-cylinder pressure detecting device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a mounting method of the cylinder pressure detecting device of the second embodiment of the present invention.

FIG. 4 is a graph showing a pressure measurement result by the mounting method of the in-cylinder pressure detecting device according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a method of mounting the cylinder pressure detecting device of the third embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a mounting method for a cylinder pressure detecting device of a fourth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a method of mounting a conventional cylinder pressure detection device.

FIG. 8 is a graph showing pressure measurement results by a mounting method of a conventional cylinder pressure detection device.

[Explanation of symbols]

 1 Cylinder pressure detection device 2 Cylinder head 3 Spark plug (mounting object) 4 Fitting part 5 Tightening nut 21 Mounting hole 40 Adhesion mechanism 41 O-ring (variable material) 42 Grooves 43, 44 Tapered part 45, 46 Step part

Claims (4)

[Claims] 1. A combustion gas in a cylinder enters a fitting portion between a mounting hole formed in a cylinder head of an engine and a mounting object in which the in-cylinder pressure detection device is inserted. A method for mounting a pressure detecting device in a cylinder, characterized by having a close contact mechanism for shutting off. 2. The method of mounting a pressure detecting device in a cylinder according to claim 1, wherein a heat-resistant annular variable material is fitted into a groove provided in the fitting portion to form the close contact mechanism. . 3. A taper portion or a step portion provided on an inner circumference of the mounting hole at a tip of a screw portion screwed at the fitting portion and a taper portion or a step portion provided on an outer circumference of the attachment are brought into pressure contact with each other. 2. The mounting method for an in-cylinder pressure detecting device according to claim 1, wherein the in-cylinder pressure detecting device is fixed to the cylinder head with a tightening nut. 4. The method for mounting the in-cylinder pressure detecting device according to claim 1, wherein the fitting portion is filled with a heat-resistant sealing material to form the close contact mechanism.