JPH0622945U - Pressure sensor mounting structure for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Structure] In the mounting structure of the pressure sensor of the internal combustion engine,
The cylinder head is arranged substantially horizontally in the vicinity of the joint surface with the cylinder block, the water jacket on the head side is arranged above the sensor, and the water jacket on the block side is arranged below the sensor. [Effect] Even if it comes into contact with the hot gas in the combustion chamber, it is effectively cooled. Also, it becomes easy to secure a space for mounting the sensor and to mount the sensor.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mounting structure for a sensor that detects pressure in a combustion chamber of an internal combustion engine.

[0002]

[Prior art]

 Recently, a method of directly detecting the pressure of the combustion chamber of the internal combustion engine to control the ignition timing is becoming popular, and at that time, the detection sensor is screwed and mounted in the cylinder head, and is further mounted in the head. A pressure introducing passage for guiding pressure to the pressure receiving portion at the tip of the sensor will be drilled. As an example thereof, the technique described in "NIKKEI ME-CHANICAL magazine, 1 April 22, 985, pages 81-82" or JP-A-59-63541 can be mentioned. The pressure sensor thus mounted usually has a piezoelectric element, and the sensor pressure receiving portion is composed of a diaphragm, which is displaced according to the combustion pressure to press the piezoelectric element and generate an electric charge proportional to the pressure. The charges are sent to the processing circuit in the subsequent stage via the charge-voltage conversion amplifier.

[0003]

[Problems to be solved by the device]

 By the way, the pressure receiving portion (diaphragm) of this pressure sensor is instantaneously exposed to the high temperature atmosphere of the combustion chamber, which reaches 2000 ° C., so that the heat may damage it. However, in the conventional mounting structure, for example, in the technique described in the above-mentioned Japanese Patent Laid-Open No. 59-63541, only the water jacket of the cylinder head is arranged in the lower part of the sensor, and the cooling effect is not sufficient. It was

Therefore, the present invention aims to eliminate the above-mentioned drawbacks of the prior art, and secures the coolability of the sensor when mounting the pressure sensor on the cylinder head, and prevents damage due to heat as much as possible. Another object of the present invention is to provide a pressure sensor mounting structure for an internal combustion engine.

[0005]

In order to achieve the above object, the present invention provides a cylinder head and a cylinder block when mounting a pressure sensor for detecting the combustion pressure of an internal combustion engine on the cylinder head. The sensor is arranged in the vicinity of the joint surface of the cylinder head so that the axis of the sensor is substantially parallel to the joint surface, and the water jacket of the cylinder head is arranged above the sensor and the water jacket of the cylinder block is arranged below the sensor. I did it.

[0006]

[Action]

 Since the water jackets are arranged close to each other above and below the pressure sensor, the cooling effect is enhanced and the degree of damage to the combustion chamber due to the high temperature gas can be reduced.

[0007]

【Example】

 Embodiments of the present invention will be described below with reference to the accompanying drawings.

For convenience of explanation, referring to FIG. 2, the air-fuel mixture in the combustion chamber 14 defined by the cylinder head 10 and the cylinder block 12 is compressed by the piston 18 and then ignited by the ignition plug 20 to explode. And generate combustion pressure. A pressure sensor 22 for detecting the pressure is screwed into the cylinder head, and an outer end portion of the pressure sensor 22 is hermetically tightened by a nut 26 integrally formed with the sensor body via a gasket 24.

The pressure sensor 22 comprises a sensor main body 28 and a pressure receiving portion 30 welded to the inner end side thereof, and the sensor pressure receiving portion 30 is composed of a diaphragm. The sensor pressure receiving portion (diaphragm) 30 is displaceable, and its displacement force presses a piezoelectric element (not shown) inside the sensor body to generate an electric charge, which charges a charge amplifier (not shown). The charge-voltage conversion is performed via the above and is sent to a processing circuit (not shown). Reference numeral 32 is a signal line of the sensor.

A pressure introducing passage 34 is formed between the combustion chamber 14 and the sensor pressure receiving portion 30 to guide the pressure of the combustion chamber to the sensor pressure receiving portion 30. FIG. 1 is an enlarged view showing the pressure introducing passage 34. As shown in the drawing, the pressure introducing passage 34 is formed in a taper shape so as to expand its diameter toward the combustion chamber side, and the diameter of the narrowest end of the passage is formed. , "L" is configured to have a diameter smaller than the diameter "d" of the sensor pressure receiving portion 30, so that even if the sensor pressure receiving portion 30 is damaged and falls off from the sensor body 28, it does not fall into the combustion chamber. To configure. Further, the pressure introducing passage is formed in a tapered shape so that its diameter varies over the entire length of the passage. As a result, when the combustion pressure wave is introduced into the passage, it does not have its own vibration frequency and the pressure peak value changes one after another, so it does not resonate with the combustion pressure, and the sensor or pressure introduction passage Will not be damaged by it.

Further, since the passage is configured to expand its diameter from the sensor pressure receiving portion side toward the combustion chamber 14, pressure can be efficiently introduced and detection accuracy is also improved.

A feature of the present invention is that the pressure sensor 22 and the cooling water passage (water jacket) 36 are arranged close to each other as shown in FIG. That is, the pressure sensor 22 is arranged in the cylinder head 10 in the horizontal direction, that is, so that the sensor axis is substantially parallel to the joint surface between the cylinder head 10 and the cylinder block 12, and the cylinder is placed above the cylinder. The cooling water passage 36 of the head 10 is arranged below the cooling water passage 36 of the cylinder block 12 as close as possible. As a result, the sensor is cooled by the water jacket of the cylinder head 10 at the upper part and by the cylinder block 12 having a lower temperature than the cylinder head 10 at the lower part. When it comes in contact with high temperature gas reaching more than that, it is cooled effectively and the degree of damage due to heat can be reduced.

Further, as described above, the pressure receiving portion 30 of the pressure sensor 22 is connected to the pressure introducing passage 34 that expands in a tapered shape toward the combustion chamber. However, since the cooling performance of the sensor is improved, It is also possible to increase the diameter of the pressure introducing passage 34 toward the combustion chamber to facilitate the entry of high temperature gas and improve the detection sensitivity of the pressure sensor 22.

As shown in FIG. 2, the pressure sensor 22 is arranged such that the sensor axis is substantially parallel to the joint surface between the cylinder head 10 and the cylinder block 12, that is, the pressure sensor 22 is arranged laterally. -Compared to the case of vertically arranging the head 10 above, it is not affected by the valve operating member and the like, the mounting space is easily secured, and the sensor mounting work is also facilitated. Further, since the ignition plug 20 and the pressure sensor 22 can be arranged separately in the combustion chamber 14, the pressure sensor 22 can be arranged at a position where the peak pressure in the latter stage of combustion can be detected, and the detection accuracy is also improved.

FIG. 3 shows another example of the pressure introducing passage. In this case, the pressure introducing passage 34a is expanded in diameter toward the sensor pressure receiving portion side. Also in this example, the diameter "l" of the narrowest end on the opening side is made smaller than the sensor pressure receiving portion diameter "d" so that the sensor pressure receiving portion 30 is prevented from falling off and resonance is also avoided.

Since the gist of the present invention is the arrangement of the sensor and the cooling water passage, the shape of the passage is not limited to the example shown in the figure. For example, the passage may be formed in a flat shape and used for blocking in the middle thereof. A configuration in which a protrusion is provided may be used. Further, the cross section of the passage in the axial direction may have any shape such as a perfect circle or an ellipse.

[0017]

[Effect of device]

 According to the present invention, when the pressure sensor for detecting the combustion pressure of the internal combustion engine is mounted on the cylinder head, the sensor axis is almost parallel to the joint surface between the cylinder head and the cylinder block. The cylinder head water jacket is placed above the sensor and the water jacket of the cylinder block is placed close to the bottom of the sensor, so that the sensor for mounting the pressure sensor on the cylinder head Coolability can be secured, the degree of damage to the sensor due to high temperature gas in the combustion chamber can be reduced, and a mounting space and mounting work can be facilitated. Further, with such a configuration, for example, the pressure introducing passage can be expanded on the combustion chamber side to facilitate introduction of high temperature gas and improve the detection sensitivity of the pressure sensor.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a pressure introducing passage of a pressure sensor.

2 is a cylinder of the internal combustion engine of the pressure sensor shown in FIG.
It is explanatory drawing which shows the attachment state to a head.

FIG. 3 is an enlarged cross-sectional view showing another example of the pressure introducing passage.

[Explanation of symbols]

14 Combustion chamber 22 Pressure sensor 28 Sensor body 30 Sensor pressure receiving portion 34, 34a Pressure introduction passage 36 Cooling water passage (water jacket)

Claims (1)

[Scope of utility model registration request] 1. When mounting a pressure sensor for detecting a combustion pressure of an internal combustion engine on a cylinder head, a sensor axis is substantially parallel to the joint surface between the cylinder head and the cylinder block. A pressure sensor mounting structure for an internal combustion engine, characterized in that the water jacket of the cylinder head and the water jacket of the cylinder block are arranged in proximity to the upper part of the sensor and the water jacket of the cylinder block, respectively.