JPH0354770B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a bolt with a built-in combustion pressure detector that integrates a bolt and a detector for detecting engine combustion pressure or knocking.

(Prior art and its problems) A piezoelectric device used to detect the combustion pressure by receiving mechanical pressure changes in the cylinder head and cylinder block due to the generation of combustion pressure in the engine, converting it into an electrical signal and outputting it. Combustion pressure detectors incorporating elements are known, and in the prior art, the detector has been attached to a cylinder head, for example, via a cylinder head bolt. That is, since the detector is constructed separately from the head bolt, the installation work is troublesome, and furthermore, since it is exposed on the upper surface of the cylinder head, it is easily damaged.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and aims to simplify the installation work of a combustion pressure detector and prevent damage to the detector.

(Means for solving the problem) In order to achieve the above object, the present invention includes:
A recess is formed between the lower surface of the bolt head and the shaft, and a pressure receiving plate receives mechanical stress vibration within the recess, and an electrode is laminated above the pressure receiving plate for deriving the electromotive force. A washer-type combustion pressure detector consisting of a plate and a piezoelectric element is fitted, and a lead-out hole through which a lead wire from the detector is led is passed through from the recess of the bolt to the center of the upper surface of the head, and the pressure-receiving pressure is The plate closes the lower opening of the recess in a fitted state and is non-rotatably engaged with the shaft of the bolt, and a member for holding a lead wire is fitted in the lead-out hole of the bolt. The present invention provides a bolt with a built-in combustion pressure detector for an engine characterized by:

(Function) (i) The combustion pressure detector is built into the recess at the bottom of the bolt head, so it is not exposed to the top of the cylinder head and will not be damaged.

(ii) Since the pressure receiving plate fits and closes the opening on the lower surface of the recess on the lower surface of the bolt head, the combustion pressure detector located inside the recess is integrated with the head bolt, making installation work easy. .

(iii) Since the pressure receiving plate is non-rotatably engaged with the shaft of the bolt, the combustion pressure detector built into the recess rotates together with the head bolt, preventing any displacement during installation. without damage.

(iv) Since a member for holding the lead wire is fitted into the lead-out hole of the bolt, ease of mounting can be improved while maintaining the detector sealing performance provided by the head bolt.

(Embodiments of the Invention) Hereinafter, each embodiment of the present invention will be described based on the accompanying drawings.

First, a first embodiment of the present invention will be described based on FIGS. 1 to 3. In FIG. 1, 1 is a piston, 2 is a cylinder, 3 is a combustion chamber, 4 is a cylinder head, 5 is a cylinder block, and 6 is a water jacket. The cylinder head 4 is connected to the cylinder block 5 via a gasket 7. , is fixed by the combustion pressure detector built-in bolt 8 of the present invention and another ordinary head bolt (not shown).

The bolt 8 of the present invention is arranged as close as possible to the cylinder 2, and an annular skirt portion 8b having a larger diameter than the hexagonal head 8a is integrally protruded from the lower part of the hexagonal head 8a. The inside of the skirt portion 8b is a recess 9 as shown in FIG. 2, and an annular combustion pressure detector 10 is fitted into the recess 9.
The detector 10 includes a pressure receiving plate 11 for receiving mechanical stress vibrations, an electrode plate 12 for deriving electromotive force, piezoelectric elements 13 and 13' that contact both sides of the electrode plate 12,
It consists of the electrode plate 12 and an insulating member 14 that insulates and protects the outer periphery of the piezoelectric elements 13, 13'.

The pressure receiving plate 11 closes the lower opening of the recess 9, and the electrode plate 12, piezoelectric elements 13, 13', and insulating member 14 are accommodated above the pressure receiving plate 11. By bending and locking the lower end of the peripheral side wall (skirt portion 8b) to the lower surface of the outer periphery of the pressure receiving plate 11, the pressure receiving plate 11 is prevented from accidentally coming off. The pressure receiving plate 1
The center hole 11a of No. 1 is non-circular as shown in FIG.
For example, it is a regular hexagon, and the cross-sectional shape of the shaft portion 8c of the bolt 8 corresponding to the center hole 11a is also a regular hexagon, whereby the pressure receiving plate 11 is prevented from rotating with respect to the shaft portion 8c. This allows the detector 10 to be prevented from rotating when the bolt 8 is tightened. In addition,
The pressure receiving plate 11 is in contact with the upper surface of the cylinder head 4 via a washer 15 in order to transmit engine combustion pressure to the piezoelectric elements 13, 13'.

A lead-out hole 9a is formed extending from the recess 9 to the center of the upper surface of the head 8a of the bolt 8, and a lead wire 16 for signal transmission connected to the electrode plate 12 passes through the lead-out hole 9a. The bolt 8 is led out from the top surface. A sealing member 17 such as a bushing is provided between the outlet hole 9a and the outer peripheral surface of the lead wire 16.
is interposed. This prevents water and the like from entering into the recess 9 from the outlet hole 9a. Also,
By leading out the lead wire 16 above the center of the upper surface of the bolt head 8a, the lead wire 16 does not get in the way even when the bolt 8 is screwed by applying a spanner or the like to the hexagonal surface of the bolt head 8a.

Next, the detection action of the combustion pressure detector built-in bolt of the present invention having the above configuration will be briefly explained.

When the air-fuel mixture in the combustion chamber 3 is ignited by a spark plug (not shown) and combustion (explosion) occurs, this combustion pressure becomes a pressure wave that causes a mechanical shock in the cylinder head 4 and cylinder block 5 that cover the combustion chamber 3. This vibration causes the bolt 8 to
A change in the tightening torque and a change in the bonding pressure between the cylinder head 4 and the cylinder block 5 occur,
The combustion pressure detector 10 senses this and outputs it as an electrical signal.

FIG. 4 shows a second embodiment of the present invention, in which the lower end side of a cylindrical cover 18 is fitted into the opening side of the lead-out hole 9a, and the inner peripheral surface of the cover 18 and the lead wire 1
A sealing member 19 is interposed between the outer peripheral surface of the cover 18 and the upper end peripheral wall of the cover 18 together with the sealing member 19 and fixed to the lead wire 16 by caulking. It is possible to prevent this from happening.

FIG. 5 shows a third embodiment of the present invention, in which the lower end side of the connector 20 is fitted and fixed to the opening side of the lead-out hole 9a, and the terminal 20a of the connector 20 is connected to the terminal 20a of the connector 20 through the lead-out hole 9a. In this example, the electrode plates 12 are connected by a lead wire 16, and the ease of mounting is further improved compared to the first and second embodiments in which the lead wire 16 extends outside the head 8a of the bolt 8. It is a diagram.

Note that the other configurations in the second and third embodiments are the same as those in the first embodiment, so the same parts in the drawings are denoted by the same reference numerals and the explanation thereof will be omitted.

(Effects of the Invention) As detailed above, according to the present invention, a recess is formed in the lower surface of the bolt head between the bolt and the shaft thereof, and a pressure receiving plate that receives mechanical stress vibrations in the recess; A washer-type combustion pressure detector consisting of an electrode plate stacked above the pressure receiving plate for deriving the electromotive force and a piezoelectric element is fitted, and a lead wire from the detector is inserted into the lead-out hole. The bolt is passed through from the recess to the center of the upper surface of the bolt, and the pressure receiving plate is fitted to close the lower opening of the recess and is non-rotatably engaged with the shaft of the bolt. Since the lead wire is fitted with a member that holds the lead wire in the lead-out hole, the detector is housed in the recess and is not exposed to the outside, thereby preventing damage. Damage can be prevented by fitting the plate into the recess opening 12 and non-rotatably engaging the bolt shaft.
Furthermore, there are effects such as ease of installation work.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
FIG. 1 is a schematic longitudinal cross-sectional view of an engine equipped with a combustion pressure detector built-in bolt of the present invention, and FIG. 2 is a longitudinal cross-sectional view of a main part of the combustion pressure detector built-in bolt of the present invention.
Figure 3 is a cross-sectional view taken along the - line in Figure 2;
The figure is a vertical cross-sectional view of a main part showing a second embodiment of the bolt of the present invention, and FIG. 5 is a vertical cross-sectional view of a main part showing a third embodiment of the same. 8... Bolt with built-in combustion pressure detector, 8a... Head of bolt with built-in combustion pressure detector, 8c... Shaft of bolt with built-in combustion pressure detector, 9... Recess, 10...
Combustion pressure detector, 11...pressure receiving plate, 9a...outlet hole, 16...lead wire, 20...connector.

Claims (1)

[Claims] 1. A recess is formed between the lower surface of the bolt head and the shaft part, and a pressure receiving plate that receives mechanical stress vibration in the recess, and a pressure receiving plate laminated above the pressure receiving plate for deriving the electromotive force. A washer-type combustion pressure detector consisting of an electrode plate and a piezoelectric element is fitted, and a lead-out hole through which a lead wire from the detector is led is passed through from the recess of the bolt to the center of the upper surface of the head. The pressure receiving plate closes the lower opening of the recess in a fitted state and is non-rotatably engaged with the shaft of the bolt, and a member for holding a lead wire is fitted into the lead-out hole of the bolt. A bolt with a built-in engine combustion pressure detector.