JPH0915075A - Pressure detector for internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pressure detection device for an internal combustion engine, which eliminates complicated handling of lead wires and improves assembly workability. An outer electrode 16 provided on an outer peripheral portion of a ring-shaped pressure sensor 1 is brought into contact with an electrode contact portion 4A provided on a plug support 4 attached to an ignition plug 2 and detected with the electrode contact portion 4A. The signal output section 4B and plug support 4
It is electrically connected via the detection signal derivation member 4C therein. As a result, the pressure detection signal from the pressure sensor 1 is
Since it is taken out from the detection signal taking-out section 4B to the outside, it is possible to abolish the conventional structure of taking out the detection signal of the pressure sensor from the lead wire which is drawn out by crawling in the vicinity of the spark plug, which is complicated. There is no need to handle lead wires, and assembly workability can be greatly improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device for an internal combustion engine, and more particularly, a ring-shaped pressure sensor is sandwiched between a cylinder head and a mounting surface of an ignition plug screwed to the cylinder head. The present invention relates to an improvement of a device for detecting the cylinder internal pressure by the output of the pressure sensor.

[0002]

2. Description of the Related Art In order to improve the fuel consumption, exhaust performance, operating performance, etc. of an internal combustion engine, it is necessary to accurately grasp the combustion state in a cylinder and to obtain the desired combustion state. It is important to precisely control the control factors (fuel supply amount, supply timing, ignition timing, etc.). From this viewpoint, it is necessary to understand the combustion state by detecting the pressure state in the cylinder. Is being carried out.

As a means for detecting the pressure state in the cylinder, for example, there is one disclosed in Japanese Unexamined Patent Publication No. 5-144543. As shown in FIG. 4, in this device, a ring-shaped pressure sensor 30 is integrally mounted on a mounting seat surface 32 of an ignition plug 31 by molding or the like, and a lead wire 33 for extracting a detection signal of the pressure sensor 30. Is led out along the outside of the spark plug 31.

There is also an example in which the ignition plug and the pressure sensor can be separated to reduce the replacement cost. As shown in FIG. 5, the ring-shaped pressure sensor 40 and the ignition plug 41 are separate structures. In some cases, the pressure sensor 40 is fixed by being sandwiched between the mounting seat surface 42 of the spark plug 41 and the cylinder head 3. The structure of the pressure sensor 40 is, for example, as shown in FIG. 6, centered on a ring-shaped center electrode 44 and two piezoelectric elements 45 on both sides thereof.
Further, an upper surface electrode 46 and a lower surface electrode 47 are sequentially laminated on the outer side thereof, and the inner and outer peripheries thereof are integrally fixed by an insulating molding member 48, and the lead wire 43 is molded from the center electrode 44. It is designed to be taken out through the member 48.

In the pressure sensor 40 fixed to the cylinder head 3 via the spark plug 41, when the combustion pressure acts on the cylinder head 3, the strain of the piezoelectric element 45 changes according to the combustion pressure, and the generated voltage changes. The characteristic is that the combustion pressure is detected.

[0006]

However, the above-mentioned conventional device has the following problems. That is, in any of the conventional examples, the lead wire is exposed to the outside of the spark plug and led out. Therefore, referring to FIG.
When the spark plug 41 is screwed onto the cylinder head 3, a so-called plug wrench, which is not shown, which is fitted in a tightening portion 41A (usually formed in a hexagonal shape) of the spark plug 41, and a so-called plug wrench of the cylinder head 3. The lead wire 43 is sandwiched between the inner peripheral portion of the mounting hole 3A of the spark plug 41 (the diameter cannot be made too large due to restrictions such as securing the cooling passage of the cylinder head 3 and the layout of the valve operating mechanism), which hinders the work. Or lead wire 4
There was a problem such as disconnection of No. 3, which caused the workability to be significantly reduced.

The present invention has been made in view of such a conventional situation, and by eliminating the complicated handling of the lead wire, it is possible to reliably prevent the breakage of the lead wire and to significantly improve the assembling workability. An object of the present invention is to provide a pressure detecting device for an internal combustion engine. It is also an object of the present invention to further improve workability.

[0008]

Therefore, in the pressure detecting device for an internal combustion engine according to the invention described in claim 1, a ring-shaped pressure sensor is sandwiched by a mounting seat surface of an ignition plug screwed to a cylinder head, In a pressure detection device for an internal combustion engine adapted to take out a detection signal of the pressure sensor as an in-cylinder pressure signal, an electrode is provided on an outer peripheral portion of the ring-shaped pressure sensor, and an electrode contact portion contacting the electrode and the electrode contact are provided. And a detection signal extracting portion electrically connected to the ignition plug, and including a spark plug capping member removably captively fixed to the spark plug.

According to the second aspect of the present invention, the electrode provided on the outer peripheral portion of the pressure sensor and the electrode contact portion contacting the electrode are fitted and contacted with each other with a predetermined fitting force,
The electrode is provided in a concave shape or a convex shape on the outer peripheral portion of the pressure sensor, and the electrode contact portion is formed in a convex shape or a concave shape corresponding to the concave shape or the convex shape of the electrode.

According to a third aspect of the present invention, a polygonal hole that fits into a polygonal portion for screwing provided on the spark plug is engraved in the spark plug crowning member, and the spark plug crowning member is also provided. A polygonal portion for screwing is formed on the outside of the. In the invention according to claim 4, the ignition plug capping member is provided with an ignition high voltage supply path.

[0011]

In the pressure detecting device for an internal combustion engine according to claim 1 having such a configuration, the detection signal of the pressure sensor is extracted from the electrode provided on the outer peripheral portion of the pressure sensor, the electrode contact portion in contact with the electrode, and the detection signal. And a spark plug crowning member,
I will take it out through. This eliminates the need for a lead wire for extracting the detection signal of the pressure sensor as in the conventional case, so that disconnection of the lead wire can be reliably avoided and the lead wire obstructs the assembly workability. It is possible to surely solve such a problem as

According to a second aspect of the invention, the electrode and
The electrode contact portion is formed in a convex shape or a concave shape so that the electrode contact portion is fitted and brought into contact with each other with a predetermined fitting force. As a result, it is possible to suppress the problem that the spark plug capping member comes off from the spark plug due to vibration of the internal combustion engine or the like. In the invention according to claim 3, a polygonal hole that fits into a threaded polygonal portion provided in the spark plug is engraved in the spark plug crowning member, and is screwed to the outside of the spark plug crowning member. Since the wearing polygonal portion is formed, when assembling the spark plug and the pressure sensor, the spark plug is previously inserted into the spark plug cap mounting member,
By fitting the pressure sensor to the electrode contact portion, the spark plug capping member, the spark plug, and the pressure sensor can be handled as one unit, and the polygonal portion provided outside the spark plug capping member is used. Since the spark plug can be securely screwed to the cylinder head, the workability can be greatly improved.

According to the fourth aspect of the invention, the ignition plug cap member is provided with the ignition high voltage supply path.
Since it is not necessary to separately prepare a long connector or the like for supplying the ignition high voltage from the ignition coil or the like to the terminal of the ignition plug, it is possible to reduce the number of parts.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. In this embodiment, as shown in FIG. 1, the ring-shaped pressure sensor 1 is configured separately from the spark plug 2 and the lead wire is not directly led out from the pressure sensor 1. There is.

That is, the structure of the pressure sensor 1 of this embodiment is as follows.
With the ring-shaped center electrode 11 as a center, two piezoelectric elements 12 are laminated on both sides of the center electrode 11, and an upper surface electrode 13 and a lower surface electrode 14 are sequentially laminated on the outer side thereof. The external electrode 16 electrically connected to the center electrode 11 is formed so as to be integrally fixed to the outer periphery of the pressure sensor 1.

Then, such a ring-shaped pressure sensor 1
As shown in FIG. 2 (A), is the seat surface 2A of the spark plug 2,
It is interposed and fixed between the cylinder head 3 and the cylinder head 3. On the other hand, the spark plug 2 is detachably surrounded by a plug support 4 as a spark plug cap mounting member according to the present invention, which is formed of an insulating resin or the like.
The pressure sensor 1 is provided below the plug support 4.
The electrode contact portion 4A that contacts the external electrode portion 16 is provided by forming a cast mold or press fitting. The electrode contact portion 4A is electrically connected to the detection signal extraction portion 4B via the detection signal derivation member 4C.

Therefore, when the pressure sensor 1 and the ignition plug 2 are screwed and fixed to the cylinder head 3 and the plug support 4 is attached to the ignition plug 2, the external electrode 16 of the pressure sensor 1 is attached.
And the electrode contact portion 4A of the plug support 4 are brought into contact with each other,
As a result, the detection signal of the pressure sensor 1 can be taken out to the detection signal taking-out section 4B. Further, the terminal 2B of the spark plug 1 is brought into contact with a spring member 4E connected to an ignition high voltage input section 4D provided in the plug support 4 when the plug support 4 is attached to the spark plug 1. It is like this.

Therefore, the detection signal (combustion pressure signal) of the pressure sensor 1 can be satisfactorily taken out from the detection signal taking-out section 4B, and the ignition high-voltage generator is connected to the ignition high-voltage input section 4D. If so, the ignition control can be satisfactorily performed. As described above, according to the present embodiment, the conventional configuration for extracting the detection signal of the pressure sensor 2 via the lead wire is abolished, and the configuration for extracting the detection signal of the pressure sensor 1 through the inside of the plug support 4 is extracted. Therefore, it is possible to surely avoid breakage of the lead wire, and it is possible to surely solve the problem that the lead wire interferes with the workability of assembling.

For example, as shown in FIG. 3, an ignition high voltage generator including a primary coil 20, a secondary coil 21, an iron core 22, a high voltage diode 23, a power switch (transistor) 24, and a pressure. The detection signal processing unit 25 of the sensor 1 and the terminals 26 and 2 connected to these.
7 is formed outside the connector 28, and the connector 28 is fitted into the recess 5 having the detection signal extracting portion 4B and the ignition high voltage input portion 4D on the inner surface. Since the score will not increase,
Workability can be maintained high.

By the way, it is sufficient for the electrode contact portion 4A and the external electrode 16 of the pressure sensor 1 to maintain contact with respect to signal extraction. Therefore, the external electrode 16 is provided on the upper surface of the pressure sensor 1, and the position where it is in contact with this. Electrode contact part 4A
May be provided. 1 and 2
As shown in (A), the shape of the contact surface of the electrode contact portion 4A with the external electrode 16 corresponds to the convex shape of the external electrode 16 (conversely may be concave shape) so that a predetermined fitting force is generated. Alternatively, it may be formed in a concave shape (conversely, it may be a convex shape). As a result, the crowning force between the spark plug 1 and the plug support 4 becomes stronger, so that the problem such as the plug support 4 coming off from the spark plug 1 due to vibration of the internal combustion engine or the like can be suppressed.

In addition to the above, the plug support 4 further includes
A hexagonal hole 6 having a shape corresponding to the shape of the tightening portion 2C (usually formed in a hexagonal shape) of the spark plug 2 is formed, and
If a hexagonal portion 7 (see FIG. 2B) that can be tightened with a plug wrench, a normal socket wrench, a spanner, or the like is formed on the upper portion of the plug support 4, the following effects can be obtained. .

That is, when the spark plug 2 and the pressure sensor 1 are assembled to the cylinder head 3, the spark plug 2 is previously inserted into the plug support 4, and the pressure sensor 1 is connected to the electrode contact portion 4A.
Since the plug support 4, the spark plug 2, and the pressure sensor 1 can be integrally handled by fitting the
Even when the spark plug 2 of the plug support 4 is inserted downward into the mounting hole 3A of the cylinder head 3, the spark plug 2 and the pressure sensor 1 can be prevented from falling off the plug support 4. The spark plug 2 and the like can be securely screwed to the cylinder head 3 via the hexagonal portion 7 provided on the upper portion of the plug support 4, so that the workability can be greatly improved.

From the cylinder head 3, the spark plug 2,
Even when the pressure sensor 1 is removed, the plug support 4, the spark plug 2, and the pressure sensor 1 can be handled as one body, so that only the pressure sensor 1 is left below the mounting hole 3A, and the pressure sensor 1 is difficult to remove. Problems such as being unable to be taken out can be prevented. by the way,
The pressure sensor 1 is not limited to the one shown in the figure, and if it is a washer pressure sensor, another type (for example, a type of piezoelectric element,
Of course, it may be any number, arrangement, etc.). Further, it goes without saying that the external electrode 16 may be provided on a part of the outer circumference of the pressure sensor 1.

Further, without providing the external electrode 16 or the like, a hexagonal hole 6 having a shape corresponding to the shape of the tightening portion 2C of the spark plug 2 is formed in the plug support 4, and the hexagonal hole is formed on the upper portion of the plug support 4. Even if only the portion 7 is formed, the plug support 4 functions as an adapter. Therefore, the hexagonal portion 7 is projected from the mounting hole 3A, and a normal tool (socket wrench) can be used without using a special tool such as a plug wrench. Or a spanner), the spark plug 2 can be screwed and fixed.

Incidentally, without providing the ignition high voltage input section 4D and the spring member 4E integrally with the plug support 4,
In FIG. 2, a portion provided with the ignition high voltage input portion 4D and the spring member 4E is formed as an opening, and a connector from an ignition coil or the like is directly inserted into the opening and connected to the terminal 2B, It may be configured to supply a high voltage for ignition. However, if configured as in the present embodiment, it is not necessary to separately prepare a long connector or the like,
It is possible to reduce the number of parts.

[0026]

As described above, according to the pressure detecting device for the internal combustion engine according to the invention described in claim 1, the lead wire for extracting the detection signal of the pressure sensor as in the prior art is unnecessary. Therefore, it is possible to reliably avoid disconnection of the lead wire, and it is possible to reliably solve the problem that the lead wire interferes with the workability of assembling.

According to the second aspect of the present invention, it is possible to suppress the problem that the spark plug cap mounting member comes off from the spark plug due to vibration of the internal combustion engine or the like. According to the third aspect of the present invention, the spark plug capping member, the spark plug, and the pressure sensor can be handled as one body, and the ignition plug can be ignited via the polygonal portion provided outside the spark plug capping member. Since the plug can be securely screwed to the cylinder head, workability can be greatly improved.

According to the invention described in claim 4, the number of parts can be further reduced and the workability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pressure sensor according to an embodiment of the present invention.

FIG. 2A is a view showing an assembled state of the pressure sensor and the spark plug in the above embodiment. (B) is I- of (A)
I sectional drawing.

FIG. 3 is a sectional view showing an example of a unit including a high voltage generator for ignition and a pressure sensor detection signal processing unit.

FIG. 4A is an overall configuration diagram illustrating an example of a conventional spark plug / pressure sensor integrated type. (B) is a partially enlarged sectional view of (A).

FIG. 5 is a diagram illustrating an example of a conventional spark plug / pressure sensor separation type.

FIG. 6 is a diagram illustrating an example of a structure of a conventional pressure sensor.

[Explanation of symbols]

 1 Pressure Sensor 2 Spark Plug 3 Cylinder Head 4 Plug Support 4A Electrode Contact Part 4B Detection Signal Extraction Part 4C Detection Signal Derivation Member 4D Ignition High Voltage Input Part 4E Spring Member 6 Hexagonal Hole 7 Hexagonal Part

Claims (4)

[Claims] 1. A pressure detecting device for an internal combustion engine, wherein a ring-shaped pressure sensor is sandwiched by a mounting seat surface of an ignition plug screwed to a cylinder head, and a detection signal of the pressure sensor is taken out as an in-cylinder pressure signal. An electrode is provided on the outer peripheral portion of the ring-shaped pressure sensor, and an electrode contact portion that is in contact with the electrode and a detection signal extraction portion that is electrically connected to the electrode contact portion are provided, and can be attached to and detached from the spark plug. A pressure detecting device for an internal combustion engine, comprising a spark plug cap member that is capped and fixed. 2. The electrode is provided on the outer peripheral portion of the pressure sensor so that the electrode provided on the outer peripheral portion of the pressure sensor and the electrode contact portion contacting the electrode are fitted and brought into contact with each other with a predetermined fitting force. The pressure of the internal combustion engine according to claim 1, wherein the electrode contact portion is provided in a concave shape or a convex shape, and the electrode contact portion is formed in a convex shape or a concave shape corresponding to the concave shape or the convex shape of the electrode. Detection device. 3. A polygonal hole that fits into a threaded polygonal portion provided on a spark plug is engraved in the spark plug crowning member, and the polygonal hole is screwed to the outside of the spark plug crowning member. The pressure detecting device for an internal combustion engine according to claim 1 or 2, wherein a portion is formed. 4. The pressure detecting device for an internal combustion engine according to claim 1, wherein the spark plug crowning member includes an ignition high voltage supply path.