JP2010249675A - Cylinder pressure detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure heat radiation without the need for such a sealing surface as to press a diaphragm part to an engine head and to eliminate a guide pipe connected to a combustion chamber. <P>SOLUTION: The diaphragm part 9 is a separate body from a sensor body and integrated with an engine head 10 in such a way as to cover the tip position of a sensor mounting hole 11 in the engine head 10. The combustion chamber and the sensor mounting hole 11 are completely partitioned from each other by being sealed by the diaphragm part 9 to prevent a fuel gas in the combustion chamber from penetrating the side of the sensor mounting hole 11, in other words, the side of the sensor body. Since the diaphragm part 9 is directly connected to the engine head 10, heat radiation is secured. Since the diaphragm part 9 has a structure integrated with the engine head 10 by being fixed in such a way as to cover the front end position of the sensor mounting hole 11, a guide pipe connected to the combustion chamber is dispensed with. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an in-cylinder pressure detecting device for detecting a pressure in a combustion chamber of an internal combustion engine.

  Conventionally, as an in-cylinder pressure detecting device for detecting a pressure in a combustion chamber of an internal combustion engine, for example, there is one disclosed in Patent Document 1. In this in-cylinder pressure detecting device, when the diaphragm is displaced according to the combustion pressure, the displacement is transmitted to the piezoelectric body, and a voltage change is caused in the piezoelectric body to detect the combustion pressure. In such an in-cylinder pressure detecting device, a diaphragm portion is provided at the tip end of the sensor body that is cylindrical, and the sensor body is inserted into an insertion hole formed in the engine head (cylinder head). A gas seal between the diaphragm portion and the engine head is performed by bringing the tip peripheral portion into contact with the contact portion of the engine head. A guide pipe constituted by a through hole extending from the tip of the sensor body into the combustion chamber is formed with respect to the engine head, and the combustion pressure is transmitted to the diaphragm portion through the guide pipe.

Japanese Patent Laid-Open No. 2005-16984

  However, in the in-cylinder pressure detecting device as described above, a seal surface that receives an axial force for realizing a gas seal is required at the distal end peripheral portion of the diaphragm portion. As described above, since the diaphragm portion and the engine head are in contact with each other at the sealing surface, it is advantageous for heat dissipation of the diaphragm portion, but high sensitivity is achieved by reducing the diameter of the tip where the diaphragm portion is arranged and expanding the pressure receiving surface.・ It is difficult to satisfy all the requirements for ensuring seal reliability.

  There is also a problem that air column vibration (a state in which the gas in the induction tube causes natural vibration) occurs in the induction tube formed between the diaphragm portion and the combustion chamber, and pressure detection accuracy deteriorates.

  In view of the above points, the present invention provides an in-cylinder pressure detection device that can ensure heat dissipation without requiring a sealing surface that presses the diaphragm portion against the engine head, and that eliminates the induction tube connected to the combustion chamber. The purpose is to do.

  In order to achieve the above object, according to the first aspect of the present invention, the pressure transmission member (11) is disposed in the sensor mounting hole (11) formed in the engine head (10) and transmits a load corresponding to the pressure in the fuel chamber. 2, 6) and a compression load detecting element (1) for generating an electrical output corresponding to the load transmitted from the pressure transmission member (2, 6), and a sensor mounting hole ( 11) A diaphragm portion that is disposed in contact with the fuel chamber at the tip position and applies a load corresponding to the combustion pressure in the combustion chamber to the pressure transmission members (2, 6) in the sensor body (1-8). (9) are provided as separate configurations. The diaphragm (9) is integrated with the engine head (10), so that the combustion chamber and the sensor mounting hole (11) are partitioned by the diaphragm (9).

  In the in-cylinder pressure detecting device having such a structure, gas sealing can be performed without requiring a sealing surface for pressing the diaphragm portion (9) against the engine head (10). Since it is directly connected to the head (10), heat dissipation can be ensured. That is, the heat received by the diaphragm portion (9) from the combustion gas can be quickly radiated to the engine head (10).

  Further, the diaphragm portion (9) is integrated with the engine head (10) by being fixed so as to cover the tip position of the sensor mounting hole (11). For this reason, it is possible to eliminate the induction pipe connected to the combustion chamber, and it is possible to eliminate the occurrence of air column vibration as in the case where the induction pipe is provided, and to prevent the pressure detection accuracy from deteriorating.

  In the invention according to claim 2, the diaphragm portion (9) forms a sensor mounting hole (11) with respect to the engine head (10), and the engine head (10) is formed at the tip of the sensor mounting hole (11). It is characterized by being formed into a thin film.

  Thus, the diaphragm part (9) is formed by integrally processing with the engine head (10). In this way, the number of parts can be reduced.

  For example, as described in claim 3, the sensor main body includes a wiring portion (3) that transmits an electrical output of the compression load detection element (1) and a compression load detection element (1) and a wiring portion (3 ) Through which the through-hole (5a) is formed and a part of the pressure transmission member, and has a spherical surface and a circular plane, and the circular plane is disposed on the compression load detecting element (1). As a result, a hemisphere (2) for applying a load to the compressive load detecting element (1) in a circular plane and a part of the pressure transmission member are formed, and added to the hemisphere (2) from the diaphragm portion (9). A rod (6) for transmitting a load to be applied, and a cylindrical member having a hollow portion for accommodating the wiring portion (3), the stem (5), the hemisphere (2) and the rod (6), and a sensor mounting hole (11 ) And an inner housing (4) fixed inside. That. The stem (5) is fixed to the inner housing (4) so that the compression load detection unit (1), the hemisphere (2), and the wiring unit (3) are positioned.

  Further, as described in claim 4, by pressing the end of the stem (5) opposite to the end where the compressive load detecting element (1) is arranged, the compressive load detecting element (1) is provided. It is also possible to provide a preload adjusting pipe (8) in which a desired load is applied.

  Thus, if the preload adjusting pipe (8) is provided, an appropriate load is applied to the compression load detecting element (1) by pushing the stem (5) by the preload adjusting pipe (8). be able to.

  In this case, as described in claim 5, the sensor main body is broken because the preload adjusting pipe (8) is accommodated in the inner housing (4), that is, not fixed to the engine head (10). Sometimes, the sensor body can be easily replaced.

  Moreover, as described in claim 6, a tube (7) surrounding the outer periphery of the rod (6) and press-fitted between the inner housing (4) and the rod (6) can be provided.

  By providing such a tube (7), it is possible to prevent the rod (6) from falling off the inner housing (4).

  The invention described in claims 7 and 8 relates to a sensor main body which is suitable when applied to the in-cylinder pressure detecting device described in claims 1 and 3. By using such a sensor main body, the in-cylinder pressure detecting device according to claims 1 and 3 can be realized.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a cross-sectional view showing a state where an in-cylinder pressure detecting device 100 according to a first embodiment of the present invention is attached to an engine head 10. FIG. (A), (b) is an exploded view of the sensor main body and other parts of the in-cylinder pressure detecting device 100 shown in FIG. It is an enlarged view of the diaphragm part 9 and the engine head 10 in the cylinder pressure detection apparatus 100 concerning 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
An in-cylinder pressure detection apparatus to which an embodiment of the present invention is applied will be described. This in-cylinder pressure detecting device is provided at the tip position of an engine head 10 provided in each cylinder of an engine provided in a vehicle, for example, and is used for detecting the fuel pressure in the combustion chamber of each cylinder. FIG. 1 shows a cross-sectional configuration of an in-cylinder pressure detecting device 100 according to the present embodiment. 2 (a) and 2 (b) are exploded views of the sensor main body and other parts of the in-cylinder pressure detecting device 100 shown in FIG. Hereinafter, based on FIG. 1, FIG. 2, the structure of the cylinder pressure detection apparatus 100 of this embodiment is demonstrated.

  As shown in FIGS. 1 and 2, the in-cylinder pressure detecting device 100 includes a compression load detecting element 1, a hemisphere 2, a wiring portion 3, an inner housing 4, a stem 5, a rod 6, a tube 7, and a preload adjusting pipe 8. A diaphragm portion 9 is provided. The in-cylinder pressure detecting device 100 detects the combustion pressure in the combustion chamber by being inserted into a sensor mounting hole 11 formed in the engine head 10 constituting a part of the combustion chamber.

  The compressive load detecting element 1 is constituted by, for example, a sensor chip based on a silicon substrate, and a piezoelectric element such as a strain gauge or a piezoresistor is formed on the surface layer portion of the silicon substrate. The compression load detecting element 1 detects the combustion pressure based on the change in the output value at the piezoelectric element when a load corresponding to the combustion pressure is applied via the hemisphere 2. For example, when the compressive load detecting element 1 is a semiconductor strain gauge type, a constant current is passed through the compressive load detecting element 1, but the resistance value changes according to the received load, and the voltage across the two ends (voltage drop) Therefore, the combustion pressure can be detected by outputting the voltage between both ends as an output value.

  The hemisphere 2 is a member that functions as a pressure transmission member together with the rod 6. The hemisphere 2 has a spherical surface and a circular plane, and the circular plane is disposed on the compression load detecting element 1. The hemisphere 2 receives a load corresponding to the combustion pressure to be detected on the spherical surface side, and pushes the surface portion of the compression load detecting element 1 on the circular plane side, thereby causing the combustion pressure to be detected on the piezoelectric element. Apply a load according to.

  The wiring unit 3 applies a desired voltage or supplies current to the compressive load detecting element 1 from an external device such as an electronic control device provided outside the in-cylinder pressure detecting device 100, or from the compressive load detecting element 1. This is for outputting an electric signal to an external device of the in-cylinder pressure detecting device 100. Specifically, the wiring portion 3 is configured by a pin 3a serving as a terminal for connection to the outside, and a bonding wire 3b for electrically connecting a desired portion of the compression load detecting element 1 and the pin 3a. Yes.

  The inner housing 4 is configured by a cylindrical member having a hollow portion. A male screw groove 4a is formed on the outer peripheral portion of the inner housing 4, and the inner housing 4 is fixed to the sensor mounting hole 11 in which the female screw groove 11a is formed using the male screw groove 4a. . In the hollow portion of the inner housing 4, the compression load detecting element 1, the hemisphere 2, the wiring portion 3, the stem 5, the rod 6, the tube 7, and the preload adjusting pipe 8 are accommodated. Specifically, the inner wall of the inner housing 4 is provided with a stepped portion 4 b that reduces the inner diameter in the direction of insertion into the sensor mounting hole 11 formed in the engine head 10. The hemisphere 2, the compression load detecting element 1, the wiring portion 3, the stem 5, and the preload adjusting pipe 8 are arranged behind the step portion 4b in the insertion direction (the side with the larger inner diameter). The rod 6 and the tube 7 are arranged on the front side (the side with the smaller inner diameter) so as to be integrated. And the sensor main body is comprised by each part integrated in this way.

  The stem 5 is designed so that the outer diameter is substantially the same as the inner diameter on the larger side of the inner housing 4. The compression load detecting element 1 and the hemisphere 2 are joined to the stem 5 by adhesion or the like, and the pin 3a of the wiring portion 3 is fixed. By fixing the stem 5 in the inner housing 4, In the inner housing 4, the compression load detecting element 1, the hemisphere 2, the wiring portion 3 and the stem 5 are positioned. The stem 5 is formed with a through hole 5a parallel to the insertion direction, and the pin 3a is disposed in the through hole 5a. Then, both ends of the pin 3a protrude from both end surfaces of the stem 5, and one end portion thereof is bonded by the bonding wire 3b, whereby the compression load detecting element 1 and the in-cylinder pressure detecting device 100 through the wiring portion 3 are used. The structure can be electrically connected to the outside.

  The rod 6 is a member that functions as a pressure transmission member together with the hemisphere 2, and is composed of, for example, a columnar member such as a cylindrical member. One end is in contact with the apex of the hemisphere 2 and the other end is in contact with the diaphragm portion 9. With this rod 6, the displacement of the diaphragm portion 9 is transmitted to the compression load detection element 1 via the hemisphere 2, and the high temperature of the combustion gas in the combustion chamber is mitigated from being transmitted to the compression load detection element 1. . The material of the rod 6 is not particularly limited. However, since the material having high Young's modulus and heat resistance and low thermal conductivity and specific gravity is preferable, the rod 6 is made of, for example, ceramic or quartz.

  The tube 7 is disposed so as to surround the outer periphery of the rod 6, and is press-fitted between the rod 6 and the side having a smaller inner diameter in the inner housing 4. Thereby, the rod 6 is prevented from falling off from the inner housing 4 and the center axis of the rod 6 is positioned. The material of the tube 7 is not particularly limited. However, since the material preferably has heat resistance and stretchability, the tube 7 is made of, for example, silicon rubber.

  The preload adjusting pipe 8 is formed of, for example, a cylindrical member, and is on the side of the stem 5 on which the compressive load detecting element 1 is arranged so that an appropriate load is applied to the compressive load detecting element 1. It is a part for pushing the end opposite to the end. An appropriate load is applied to the compression load detecting element 1 by pushing the stem 5 by the preload adjusting pipe 8, and the preload adjusting pipe 8 is fixed to the inner housing 4 in this state. The fixing method of the preload adjusting pipe 8 to the inner housing 4 may be any method such as screw fastening, press-fitting, adhesion, or welding. In this embodiment, the outer edge of the end surface of the preload adjusting pipe 8 is used. It is fixed by the welded part 12 which has been welded at the part. As described above, since the preload adjusting pipe 8 is fixed to the inner housing 4, that is, not fixed to the engine head 10, the sensor main body can be easily replaced even when the sensor main body breaks down. It becomes. The pin 3a passes through the hollow portion of the preload adjusting pipe 8 and is pulled out to the side opposite to the stem 5, and can be electrically connected to the outside.

  The diaphragm portion 9 is separate from the sensor main body and is integrated with the engine head 10 by being fixed so as to cover the tip position of the sensor mounting hole 11 in the engine head 10. By being sealed by the diaphragm portion 9, the combustion chamber and the sensor mounting hole 11 are completely partitioned, and the fuel gas in the combustion chamber is prevented from entering the sensor mounting hole 11, that is, the sensor body side. Yes.

  The diaphragm portion 9 is made of, for example, a heat-resistant metal and is fixed to the engine head 10 by press-fitting, bonding, welding, or the like. Specifically, the diaphragm portion 9 has a circular shape with an inner portion recessed from the outer edge portion, and is fixed to the engine head 10 at the outer edge portion, and the rod 6 is brought into contact with the recessed portion inside the outer edge portion. It has been. For this reason, the recessed part inside the outer edge part of the diaphragm part 9 is displaced according to the combustion pressure, and this displacement is transmitted to the compression load detecting element 1 through the rod 6 and the hemisphere 2. Yes.

  The in-cylinder pressure detecting device 100 according to the present embodiment is configured by the structure as described above. In the in-cylinder pressure detecting device 100 having such a structure, when a combustion pressure in the combustion chamber is applied to the diaphragm portion 9, a load based thereon is transmitted to the hemisphere 2 through the rod 6. Then, the load is transmitted from the hemisphere 2 to the compression load detection element 1, and an electrical output corresponding to the load transmitted from the compression load detection element 1 is generated. This electrical output is transmitted as an output corresponding to the combustion pressure to the external device provided outside the in-cylinder pressure detection device 100 through the wiring portion 3, so that the combustion pressure can be transmitted to the external device.

  In the in-cylinder pressure detecting device 100 having such a structure, gas sealing can be performed without requiring a sealing surface for pressing the diaphragm portion 9 against the engine head 10, and the diaphragm portion 9 is directly connected to the engine head 10. Therefore, heat dissipation can be secured. Since the heat received by the diaphragm 9 from the combustion gas can be quickly dissipated to the engine head 10, the thermal load received by the diaphragm 9 and the compression load detecting element 1 can be greatly reduced, and the heat resistance of the sensor can be improved. Output errors due to displacement due to thermal expansion of the diaphragm portion 9 can be suppressed.

  In addition, the diaphragm portion 9 is integrated with the engine head 10 by being fixed so as to cover the tip position of the sensor mounting hole 11. For this reason, it is possible to eliminate the induction pipe connected to the combustion chamber, and it is possible to eliminate the occurrence of air column vibration as in the case where the induction pipe is provided, and to prevent the pressure detection accuracy from deteriorating.

  Further, since the diaphragm portion 9 and the engine head 10 are joined around the diaphragm portion 9, the joint portion is sealed. This eliminates the need to consider the influence of the axial force acting on the sensor body as compared to the conventional seal based on the axial force caused by the contact between the sealing surface at the tip of the diaphragm and the sensor mounting hole. The effect of improving the degree is also obtained. For example, it is not necessary to secure a thickness that can withstand the axial force as the thickness of the inner housing 4 and the like, and it is possible to reduce the diameter of the sensor body.

(Second Embodiment)
A second embodiment of the present invention will be described. The basic structure of the in-cylinder pressure detecting device 100 of this embodiment is the same as that of the first embodiment, and only the structure of the diaphragm portion 9 is different from that of the first embodiment. For this reason, only a different part from 1st Embodiment among the cylinder internal pressure detection apparatuses 100 of this embodiment is demonstrated.

  FIG. 3 is an enlarged view of the diaphragm portion 9 and the engine head 10 in the in-cylinder pressure detecting device 100 of the present embodiment.

  As shown in this figure, in the in-cylinder pressure detecting device 100 of the present embodiment, the sensor mounting hole 11 is formed by drilling the engine head 10 or the like, and the tip of the sensor mounting hole 11 is displaced by the combustion pressure. The diaphragm portion 9 is formed by thinning the film so as to have a possible thickness. That is, the diaphragm portion 9 is formed by being integrally processed with the engine head 10. In this way, the number of parts can be reduced.

(Other embodiments)
The structure of the in-cylinder pressure detection device 100 described in the above embodiments is merely an example, and various design changes can be made. For example, since the inner housing 4 is fixed to the engine head 10 by screw fastening, the inner housing 4 has a cylindrical shape. However, if these are joined by welding or the like, the shape of the inner housing 4 is not necessarily cylindrical. There is no need to do. The material of each component is merely an example, and a material different from the above material can be used.

DESCRIPTION OF SYMBOLS 1 Compression load detection element 2 Hemisphere 3 Wiring part 4 Inner housing 5 Stem 6 Rod 7 Tube 8 Preload adjustment pipe 9 Diaphragm part 10 Engine head 11 Sensor mounting hole 12 Welding part 100 In-cylinder pressure detection apparatus

Claims (8)

A pressure transmission member (2, 6) that is disposed in a sensor mounting hole (11) formed in the engine head (10) and transmits a load corresponding to the pressure in the fuel chamber, and the pressure transmission member (2, 6) A sensor body (1-8) having a compression load detection element (1) for generating an electrical output corresponding to the transmitted load;
At the tip of the sensor mounting hole (11), it is disposed in contact with the fuel chamber, and the combustion pressure in the combustion chamber with respect to the pressure transmission member (2, 6) in the sensor body (1-8). And a diaphragm portion (9) for applying a corresponding load,
In-cylinder pressure, wherein the diaphragm (9) is integrated with the engine head (10), whereby the combustion chamber and the sensor mounting hole (11) are partitioned by the diaphragm (9). Detection device.   The diaphragm portion (9) forms the sensor mounting hole (11) in the engine head (10), and thins the engine head (10) at the tip of the sensor mounting hole (11). The in-cylinder pressure detecting device according to claim 1, wherein the in-cylinder pressure detecting device is configured. The sensor body is
A wiring portion (3) for transmitting an electrical output of the compression load detecting element (1);
A stem (5) in which a through hole (5a) through which the compressive load detecting element (1) is bonded and the wiring portion (3) is passed is formed;
A part of the pressure transmission member is formed, and has a spherical surface and a circular plane, and the circular plane is disposed on the compression load detection element (1), whereby the compression load detection element is formed on the circular plane. A hemisphere (2) that applies a load to (1);
A rod (6) that constitutes part of the pressure transmission member and transmits a load applied from the diaphragm (9) to the hemisphere (2);
The wiring portion (3), the stem (5), the hemisphere (2), and a cylindrical member having a hollow portion that accommodates the rod (6) are configured and fixed in the sensor mounting hole (11). An inner housing (4),
By fixing the stem (5) to the inner housing (4), the compression load detection part (1), the hemisphere (2) and the wiring part (3) are positioned. The in-cylinder pressure detecting device according to claim 1 or 2.   A desired load is applied to the compressive load detecting element (1) by pushing the end of the stem (5) opposite to the end where the compressive load detecting element (1) is disposed. The in-cylinder pressure detecting device according to claim 3, further comprising a preload adjusting pipe (8) configured to be in a state of being made to move.   The in-cylinder pressure detecting device according to claim 4, wherein the preload adjusting pipe (8) is accommodated in the inner housing (4).   6. The tube according to claim 3, further comprising a tube (7) surrounding the outer periphery of the rod (6) and press-fitted between the inner housing (4) and the rod (6). The in-cylinder pressure detecting device according to claim 1. The combustion chamber and the sensor are arranged in a sensor mounting hole (11) formed in the engine head (10) and are integrated with the engine head (10) at a tip position of the sensor mounting hole (11). A pressure transmission member (2, 6) for partitioning the mounting hole (11) and contacting a diaphragm portion (9) for applying a load corresponding to the combustion pressure in the combustion chamber, and transmitting a load corresponding to the pressure in the fuel chamber;
A sensor body comprising a compression load detecting element (1) for generating an electrical output corresponding to a load transmitted from the pressure transmitting member (2, 6). A wiring portion (3) for transmitting an electrical output of the compression load detecting element (1);
A stem (5) in which a through hole (5a) through which the compressive load detecting element (1) is bonded and the wiring portion (3) is passed is formed;
A part of the pressure transmission member is formed, and has a spherical surface and a circular plane, and the circular plane is disposed on the compression load detection element (1), whereby the compression load detection element is formed on the circular plane. A hemisphere (2) that applies a load to (1);
A rod (6) that constitutes part of the pressure transmission member and transmits a load applied from the diaphragm (9) to the hemisphere (2);
The wiring portion (3), the stem (5), the hemisphere (2), and a cylindrical member having a hollow portion that accommodates the rod (6) are configured and fixed in the sensor mounting hole (11). An inner housing (4),
By fixing the stem (5) to the inner housing (4), the compression load detection part (1), the hemisphere (2) and the wiring part (3) are positioned. The sensor main body according to claim 7.

Images