JP6286355B2 - Functional component unit with combustion pressure sensor for internal combustion engines - Google Patents

Description

  The present invention relates to a pressure sensor, and more particularly to a functional component unit with a combustion pressure sensor for an internal combustion engine that detects the pressure in the combustion chamber by mounting the combustion pressure sensor on a functional component attached to the combustion chamber of the internal combustion engine.

  As a device attached to a combustion chamber of an internal combustion engine to detect the pressure in the combustion chamber, a combustion pressure sensor using a piezoelectric element as a pressure detection unit has been proposed. This type of combustion pressure sensor has a configuration in which a cylinder head is individually attached to a through hole formed in a predetermined position of the cylinder head, and a device attached to an injector, a spark plug, or the like that is a functional component attached to an internal combustion engine. What was comprised so that it might be attached was known.

  Here, Patent Document 1 is cited as an example of a combustion pressure sensor configured to be mounted on a spark plug or the like, which is a functional component attached to an internal combustion engine. The spark plug with a built-in pressure sensor disclosed in Patent Document 1 is provided with a ring-shaped combustion pressure sensor attached to the outer periphery of the ignition plug, and the combustion pressure sensor is tightened together with the ignition plug on the outside of the cylinder head. It is configured to detect and control the internal combustion engine in accordance with the combustion pressure. FIG. 13 shows a cross-sectional view of a conventional ignition plug with a combustion pressure sensor shown in FIG. The configuration will be described below with reference to FIG. In addition, in order to make it easy to understand, the names of the parts are arranged in the present application within a range not departing from the gist of the invention.

  In FIG. 13, the combustion pressure sensor 45 in the ignition plug unit 300 with the combustion pressure sensor is formed in a ring shape on the outer periphery of the metal shell 46 a of the ignition plug 46. The combustion pressure sensor 45 formed on the outer periphery of the spark plug 46 is fixed to the outside of the cylinder head together with the gasket 30 by inserting and tightening the spark plug 46 in a spark plug mounting hole 48 a provided in the cylinder head 48. . In this combustion pressure sensor 45, the combustion pressure generated in the combustion chamber C is transmitted from the bottom surface of the sensor case 31 to the piezoelectric element 33 through the plate packing 32 via the gasket 30. The electric signal generated from the piezoelectric element 33 is taken out from the spark plug unit 300 from the electrode plate 34 via the terminal portion 34a of the electrode plate 34 and the joint portion of the terminal portion 34a and the signal line 47. it can. Further, the electric signal is sent to the control device via the signal processing unit, and the internal combustion engine is controlled. Further, in order to prevent the piezoelectric element from being damaged due to stress concentration on the piezoelectric element 33 by the electrode plate 34 in the combustion pressure sensor 45 due to tightening of the spark plug 46, the electrode plate 34 and the housing member 35 are prevented. The configuration of the insulating plate 36 is devised.

JP 2000-277233 A

  The conventional ignition plug unit with a combustion pressure sensor described in Patent Document 1 has a configuration in which the combustion pressure sensor portion is fixed to the outer surface 48b of the cylinder head by tightening the ignition plug. The signal can be taken directly outside the cylinder head without passing through the cylinder head. Therefore, even if the signal line portion is not sealed, there is no concern that the mixed gas or the combustion gas leaks outside the cylinder head through the signal line portion. However, since the combustion pressure sensor 45 is configured to be fastened together with the ignition plug 46 on the outside of the cylinder head, there is a concern that the signal to be detected may be affected and fluctuate due to fluctuations in the tightening load.

  In general, in a pressure detection device using a piezoelectric element, it is necessary to apply a predetermined load (preload) in order to increase the sensitivity and linearity of the piezoelectric element during assembly. In the conventional example, the combustion pressure sensor 45 is fastened and fixed to the outer surface 48b of the cylinder head 48 while being fixed to the outer periphery of the metal shell 46a constituting the spark plug 46, and is preloaded. In the conventional example, the pressure accompanying the combustion of the air-fuel mixture in the combustion chamber acts on the tip of the spark plug 45 and acts in the direction opposite to the load for tightening the spark plug. The combustion pressure sensor 45 is configured to detect a variation in the tightening load of the spark plug as a combustion pressure.

  However, the spark plug is a consumable item, and the electrode portion is consumed due to discharge and deteriorates in performance. Therefore, the spark plug needs to be replaced, and is performed by an unspecified worker such as a consumer or a trader. Therefore, in the spark plug unit with a combustion pressure sensor shown in the conventional example, there is a concern that the tightening load varies every time the spark plug unit is replaced. In that case, the preload applied to the piezoelectric element fluctuates, the detection signal is affected, and there is a problem that the reliability decreases as a means for detecting the pressure in the combustion chamber. Further, there is a concern that the pressure detection unit may be damaged due to excessive tightening.

  An object of the present invention is to solve the above-mentioned problems, and is a functional part unit with a combustion pressure sensor attached to an internal combustion engine, and the performance is hardly affected by the tightening load of the functional part. An object of the present invention is to provide a functional part unit with a combustion pressure sensor for an internal combustion engine that is provided with a means for preventing the mixed gas and combustion gas from leaking outside the cylinder head.

  In order to solve the above-described problem, a functional component unit with a combustion pressure sensor for an internal combustion engine according to the present invention has a ring-shaped combustion pressure sensor formed on the outer peripheral surface of the tip of the functional component attached to the combustion chamber of the internal combustion engine. In the functional component unit for detecting the internal pressure of the combustion chamber by mounting the combustion pressure sensor, the combustion pressure sensor includes an outer cylinder part constituting the outer peripheral surface and an inner cylinder part constituting the inner peripheral surface, and a housing unit of the housing unit. A pressure-receiving ring block portion provided in front of the combustion chamber side, the front surface of which is a pressure-receiving surface, a piezoelectric element that is disposed in the housing unit and detects a pressure from the pressure-receiving ring block portion, and provided behind the housing unit; A support ring block portion that supports the piezoelectric element, and the thickness of the inner cylinder portion is selected to be larger than the thickness of the outer cylinder portion. In a state of being attached to the distal end outer peripheral surface of the component, and wherein each of the inner peripheral surface of the combustion pressure sensor in contact with the outer peripheral surface and the functional parts of the combustion pressure sensor in contact with the functional component be provided with a sealing means.

  In this case, according to a preferred aspect of the invention, welding can be used for the sealing means provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the functional component. At this time, it is desirable to use laser welding as welding and continuously weld over one round. In addition, the outer peripheral surface and inner peripheral surface of the combustion pressure sensor which performs welding can include the edge part of the said outer peripheral surface and inner peripheral surface. On the other hand, a stepped portion that engages with the outer peripheral surface of the functional component can be provided on the inner peripheral surface of the support ring block portion. Specifically, a step portion is provided between the outer peripheral surface of the functional component and the inner peripheral surface of the combustion pressure sensor by forming a ring-shaped protrusion protruding in the center direction from the inner peripheral surface of the combustion pressure sensor, The tip of the projection and the outer peripheral surface of the functional component can be welded. On the other hand, one of the sealing means provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the functional component can be welded and a gasket can be used for the other. At this time, the gasket is made of metal or non-metal having a predetermined thickness and elasticity, and can be formed in a ring shape as a whole. When mounting the gasket, a stepped portion may be formed on the outer peripheral surface of the functional component, and a gasket may be interposed between the stepped portion and the end surface of the combustion pressure sensor, or on the inner peripheral surface of the combustion pressure sensor. A step portion may be formed, and a gasket may be interposed between the step portion and the second step portion formed on the outer peripheral surface of the functional component. For the functional parts, it is preferable to apply an injector that injects fuel into the combustion chamber or an ignition plug that ignites the air-fuel mixture in the combustion chamber.

  According to the functional component unit with a combustion pressure sensor for an internal combustion engine according to the present invention having such a configuration, the following remarkable effects are obtained.

  (1) According to the present invention, in the functional component unit in which the ring-shaped combustion pressure sensor is mounted on the outer peripheral surface of the tip of the functional component attached to the combustion chamber of the internal combustion engine, the combustion pressure sensor in contact with the functional component By providing sealing means on the outer peripheral surface and inner peripheral surface respectively, it is possible to seal between the functional component and the combustion pressure sensor, and mixing to the outside of the detection element unit and cylinder head through the signal wire guide hole Gas and combustion gas can be prevented from leaking.

  (2) Moreover, the detection performance is not affected by the tightening load of the functional component due to the configuration in which the combustion pressure sensor is attached to the tip of the functional component. As a result, it is possible to provide a functional component unit with a combustion pressure sensor for an internal combustion engine that is excellent in reliability without gas leakage and being not affected by the tightening load.

  (3) According to a preferred embodiment, if welding is used as the sealing means provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the functional component, in addition to the sealing between the functional component and the combustion pressure sensor, the combustion pressure sensor Can be securely attached (fixed) to functional parts.

  (4) According to a preferred embodiment, when laser welding is used as welding and continuous welding is performed over one round, sealing can be reliably performed, and sealing performance and mounting strength can be enhanced.

  (5) According to a preferred embodiment, if the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor to be welded include the edge portions of the outer peripheral surface and the inner peripheral surface, for example, the tip of the outer peripheral surface of the functional component burns. Even if the configuration is such that it is positioned forward of the tip of the inner peripheral surface of the pressure sensor, it can be reliably fixed by combining the end edge portion and the end surface of the inner peripheral surface of the combustion pressure sensor.

  (6) According to a preferred embodiment, a stepped portion is formed between the outer peripheral surface of the functional component and the inner peripheral surface of the combustion pressure sensor by forming a ring-shaped protrusion protruding in the center direction from the inner peripheral surface of the combustion pressure sensor. If the tip of the projection and the outer peripheral surface of the functional part are welded, the functional part can be welded at a position away from the detection part. The occurrence of thermal strain on the surface can be suppressed, and a highly accurate pressure signal can be maintained.

  (7) According to a preferred embodiment, if one of the sealing means provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the functional part is welded and a gasket is used for the other, the welding process can be reduced, and assembly is performed. Man-hours can be reduced.

  (8) According to a preferred embodiment, the gasket may be formed with a stepped portion on the outer peripheral surface of the functional component and interposed between the stepped portion and the end surface of the combustion pressure sensor, or a stepped portion on the inner peripheral surface of the combustion pressure sensor. May be interposed between the stepped portion and the second stepped portion formed on the outer peripheral surface of the functional component. As described above, the gasket can be used on either the outer peripheral surface or the inner peripheral surface of the combustion pressure sensor, can flexibly cope with it, and can increase the degree of freedom in design.

It is a conceptual diagram which shows the state which attached the injector unit in 1st Embodiment which concerns on this invention to the internal combustion engine. It is the S section enlarged view of FIG. It is a perspective view which shows the mounting structure of the combustion pressure sensor of FIG. It is sectional drawing which shows the mounting structure of the combustion pressure sensor of FIG. FIG. 4 is an exploded perspective view of the combustion pressure sensor shown in FIG. 3. It is a fragmentary sectional view of the injector unit shown in FIG. FIG. 7 is a detailed view of a T portion and a detailed view of a U portion in FIG. 6. It is VV sectional drawing of FIG. It is a fragmentary sectional view of an injector unit in a 2nd embodiment concerning the present invention. It is a fragmentary sectional view of an injector unit in a 3rd embodiment concerning the present invention. It is a fragmentary sectional view of an injector unit in a 4th embodiment concerning the present invention. It is a fragmentary sectional view of a spark plug unit in a 5th embodiment concerning the present invention. It is sectional drawing which shows the structure of the ignition plug unit with a combustion pressure sensor which concerns on background art.

  DESCRIPTION OF SYMBOLS 1: Internal combustion engine, 2: Cylinder block, 2a: Cylinder, 3: Piston, 4: Cylinder head, 4a: Communication hole, C: Combustion chamber, P, Q: Outer corner of functional part, h: Outer part of functional part Surface, i: outer peripheral surface of combustion pressure sensor, j: inner peripheral surface of combustion pressure sensor, p: outer peripheral corner of combustion pressure sensor, 5: spark plug (functional component), 5A: spark plug unit (functional component unit) , 6, 6A, 6B, 6C, 6D: Injector unit (functional part unit), 7, 7A, 7B, 7C, 7D: Injector (functional part), 8, 8A, 8B, 8C, 8D: Combustion pressure sensor, 10 : Pressure detector, 10a: Opening, 11: Front outer casing (outer cylinder), 12: Front inner casing (inner cylinder), 13: Rear casing (support ring block), 14: Pressure receiving ring ( Pressure ring block), 15 Pressure transmission ring, 16: Piezoelectric element (piezoelectric element group), 17: Spacer (spacer group), 50: Transmission section, 51: Transmission wire, 52: Connection terminal, 53: Connection pipe, 55, 55a, 55b: Positioning tube , 56: Coil spring, 57, 57a, 57b: Sealing part, 60, 61, 62: Gasket, 70: Electrical connector part, 80: Fuel connector part, 100: Signal processing part, 200: Control device, 300: Conventional Spark plug unit with combustion pressure sensor

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  In addition, the combustion pressure sensor in embodiment described below demonstrates in the example attached to the injector which is a functional component of an engine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the embodiment described below exemplifies a combustion pressure sensor for embodying the idea of the present invention, and the present invention is not limited to the following configuration. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are merely illustrative examples rather than limiting the scope of the present invention unless otherwise specified. . In addition, the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. In the following description, the same parts and the same components are denoted by the same names and reference numerals, and detailed description may be omitted as appropriate.

First, features of the embodiments of the present invention will be described.
In general, an injector, a spark plug, a glow plug, and the like are assumed as a functional component attached to a combustion chamber of an internal combustion engine. An injector unit or spark plug unit equipped with a combustion pressure sensor will be described below.

  The feature of the first embodiment is a basic configuration example of the present invention, in which the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the injector are sealed by welding, respectively, and the signal lines are guided through the guide holes. This is an injector unit that prevents combustion gas leakage. The feature of 2nd Embodiment is the injector unit which provided the gasket in one side of the seal part and prevented combustion gas leak. A feature of the third embodiment is an injector unit that prevents a combustion gas leak by providing a step portion between the inner peripheral surface of the combustion pressure sensor and disposing a gasket at the step portion. The feature of 4th Embodiment is the injector unit which provided the ring-shaped projection part in the internal peripheral surface of a combustion pressure sensor, and suppressed the distortion by welding heat. A feature of the fifth embodiment is an ignition plug unit in which a combustion pressure sensor is attached to the outer peripheral surface of the tip end portion of the ignition plug.

First embodiment

  First, as a first embodiment of the present invention, a schematic configuration in which an injector unit is attached to a general internal combustion engine will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of the internal combustion engine 1, and FIG. 2 is an enlarged view of a portion S in FIG.

  In FIG. 1, reference numeral 1 denotes an internal combustion engine in which an injector unit 6A with a combustion pressure sensor for an internal combustion engine of the present invention is incorporated. The internal combustion engine 1 includes a cylinder block 2 in which a cylinder 2 a and a cylinder head 4 are fastened, a piston 3 that reciprocates in the cylinder block 2, and the like, and a combustion chamber C is configured by the cylinder block 2 and the piston 3. doing.

  When the internal combustion engine 1 is a gasoline engine or the like, it is usually attached to the cylinder head 4 and attached to the cylinder head 4 and an ignition plug 5 (shown by a one-dot chain line) for burning the air-fuel mixture in the combustion chamber C. And an injector unit 6A for injecting fuel into the combustion chamber C. The injector unit 6A is integrated with a combustion pressure sensor 8A configured in a ring shape at the tip of the injector 7A. In addition, the injector unit 6A is mounted such that the sensor portion is located near the combustion chamber C.

  Next, a configuration in which the injector unit 6A is attached to the cylinder head 4 will be described with reference to FIG. In FIG. 2, the cylinder head 4 is provided with a communication hole 4a for communicating the combustion chamber C for attaching the injector unit 6A with the outside. The shape of the communication hole 4a is larger than the hole diameter of the first hole 4b, the second hole 4c larger than the hole diameter of the first hole 4b, and the second hole 4c from the combustion chamber C side. And a third hole 4d. The injector unit 6A is attached in a state of penetrating the communication hole 4a, and is configured such that the combustion pressure sensor 8 is positioned near the combustion chamber C of the first hole 4b, and the hole diameter of the first hole 4b. The outer diameter of the combustion pressure sensor 8 is slightly smaller.

  Further, the body 6a of the injector unit 6A is inserted into the second hole 4c together with the gasket 60, and is fitted with a clearance fit. Further, the flange portion 6b of the injector unit 6A is inserted into the third hole portion 4d. The injector unit 6A clamps the flange portion 6b by a clamp portion (not shown) provided outside the cylinder head 4 and is fixed together with the gasket 60. Thereby, airtightness can be maintained so that air-fuel mixture and combustion gas do not leak from the combustion chamber C side.

  In FIG. 1, an injector unit 6A supplies fuel to an electric connector portion 70 for transmitting and connecting a pressure signal detected by a combustion pressure sensor 8A attached to the outer periphery of the tip portion to the outside, and the injector 7A portion. A fuel connector portion 80 is provided. Further, the internal combustion engine 1 includes a signal processing unit 100 that receives and amplifies an electric signal that is a weak charge obtained from the piezoelectric element, and further receives control of the processed signal and instructs the injector 7A to perform predetermined control. A device 200 is provided. Thus, the injector unit 6A is configured to perform predetermined fuel injection according to an instruction from the control device in accordance with the combustion pressure.

  Next, the configuration of the injector unit 6A will be described with reference to FIGS. 3 is a perspective view showing a configuration in which a combustion pressure sensor 8A is mounted on an injector 7A, which is one of the functional components in FIG. 2, and FIG. 4 is a cross-sectional view showing the configuration. FIG. 5 is an exploded perspective view of the combustion pressure sensor 8A, FIG. 6 is a sectional view of the combustion pressure sensor 8A mounted on the injector 7A (injector unit 6A), and FIG. FIG. 8 is a detailed view of the U portion, and FIG.

  Next, a configuration for suitably mounting the combustion pressure sensor 8A and the injector 7A will be described using FIG. 3 and FIG. FIG. 3 is a perspective view showing a state in which the combustion pressure sensor 8A is mounted on the outer periphery of the tip end portion of the injector 7A. FIG. 4 shows the combustion pressure sensor 8A and the injector 7A when the combustion pressure sensor 8A and the injector 7A are assembled. It is sectional drawing which shows how is touched.

  In FIG. 3, a step is provided at the tip of the injector 7A, and the opening 10a of the combustion pressure sensor 8A is fitted to the step. A transmission unit 50 that transmits a signal from the pressure detection unit 10 of the combustion pressure sensor 8 </ b> A extends toward the rear end surface, and passes through a guide hole of a signal line provided in the injector 7. At this time, the signal hole hole is sealed by sealing portions 57a and 57b described later.

  Next, in FIG. 4, the situation where the inner peripheral surface and the outer peripheral surface of the combustion pressure sensor 8A are in contact with the outer peripheral surface of the tip end portion of the injector 7A will be described in detail. An alternate long and short dash line at the tip of the injector 7A indicates the outer peripheral surface h, and alternate long and short dash lines at the outer side and the inner side of the combustion pressure sensor 8A indicate the outer peripheral surface i and the inner peripheral surface j, respectively. Therefore, the surface located on both sides between the outer peripheral surface i and the inner peripheral surface j is an end surface of the combustion pressure sensor. Further, points P and Q on the outer peripheral surface h of the injector 7A indicate corner portions of the stepped portion, and a point p on the outer peripheral surface i of the combustion pressure sensor 8A indicates the corner portion of the casing of the combustion pressure sensor 8A. When the combustion pressure sensor 8A is fitted to the tip of the injector 7A, the corner P of the injector 7A and the corner p of the combustion pressure sensor 8 are in contact, and the corner Q of the injector 7A is the inner peripheral surface j of the combustion pressure sensor 8A. Is in contact with These two contact points are the seal portion. Usually, the signal line is sealed with a sealing member in the signal line guide hole, but complete sealing is difficult. However, by providing the seal portions at these two locations, the air-fuel mixture and the combustion gas can be sealed so as not to leak into the signal hole. As a result, the combustion pressure sensor 8A can be mounted on the injector 7A and sealed.

  The above-mentioned “contact” means contact within a range that can be sealed by a sealing means (welding, gasket, etc.). For example, sealing is possible even if the position is slightly shifted in the radial direction or the center line direction. If there is no problem. In the following description, as a sealing means, a “welded part” using laser welding or the like is given a convenience “●” mark, but does not indicate an actual shape, but simply indicates a “welded part”. It is a mark. In the following description, the combustion pressure sensor 8A side located at the left end in FIG. 3 or FIG. 4 is referred to as the front end surface side, and the right end side is referred to as the rear end surface side. Further, a direction along the center line shown in FIG. 3 or FIG. 4 is referred to as a center line direction.

  Next, the structure of the pressure detection part 10 is demonstrated using FIGS. The combustion pressure sensor 8A includes a pressure detection unit 10 having a function of detecting pressure, and a transmission unit 50 that transmits the pressure detected by the pressure detection unit 10 to the outside as an electrical signal. The pressure detection unit 10 has a cylindrical shape as a whole, and is provided with an opening 10 a that penetrates from the front end surface side to the rear end surface side and accommodates the distal end portion of the injector 7. The transmission unit 50 extends along the direction of the center line, the end on the front end face side is accommodated in the pressure detection unit 10, and the rear end face side has a signal wire guide hole provided in the injector 7 as the transmission wire 51. It is connected to the electric connector part 70 of the street injector 7 (refer FIG. 2).

  The pressure detection unit 10 includes a front outer casing 11 having a cylindrical shape, and a front inner casing having a cylindrical shape and disposed concentrically with the front outer casing 11 inside the front outer casing 11. A body 12, a rear housing 13 having a cylindrical shape and attached to the rear side of the front outer housing 11 and the front inner housing 12, and an annular shape and the front outer housing 11 and the front inner housing. A pressure receiving ring 14 attached to the front end surface side of the body 12 and receiving pressure from the outside is provided. Thus, the assembly of the front outer casing 11, the front inner casing 12, the rear casing 13, and the pressure receiving ring 14 has a function as a casing of the entire pressure detection unit.

  Further, the pressure detection unit 10 is formed with an internal space 10b surrounded by the front outer casing 11, the front inner casing 12, the rear casing 13, and the pressure receiving ring 14. The pressure detection unit 10 has a ring shape in the internal space 10b and is disposed on the rear end face side of the pressure receiving ring 14, and further transmits the pressure from the pressure receiving ring 14 to the rear end face side. 15 and a piezoelectric element group 16 that is disposed between the rear end surface of the pressure transmission ring 15 and the front end surface of the rear housing 13 and converts the pressure transmitted from the pressure transmission ring 15 into a charge signal. In the present embodiment, the piezoelectric element group 16 is provided with the first to sixth piezoelectric elements 16 provided at intervals of 60 ° in the circumferential direction on the rear end face side of the pressure transmission ring 15. . In the present embodiment, the six piezoelectric elements 16 to 16 are arranged at substantially equal intervals, but the number of the piezoelectric element groups 16 may be less than six or more. Therefore, the number may be one.

  In the present embodiment, each piezoelectric element 16 has a piezoelectric function of generating electric charge upon receiving pressure, but has a piezoelectric function added as a plurality of piezoelectric element groups 16. In the pressure detector 10, spacer groups 17 are arranged between the piezoelectric elements 16 described above at intervals of 60 ° in the circumferential direction. In this manner, by arranging the spacers 17 to 17 so as to fill the space between the piezoelectric elements 16, the alignment adjustment of the piezoelectric element group 16 is assisted during the assembly of the pressure detection unit, and the alignment adjustment is facilitated. Can be done accurately.

  Next, the structure of each housing | casing is demonstrated using FIGS. The front outer casing 11 has a cylindrical shape, and a notch for fitting the outer end portion of the pressure receiving portion 14a of the pressure receiving ring 14 is formed inside the end portion on the front end face side. . Similarly, the front inner casing 12 has a cylindrical shape, and the outer diameter thereof is smaller than the inner diameter of the front outer casing 11. Further, a notch for fitting the inner end portion of the pressure receiving portion 14a of the pressure receiving ring 14 is formed on the outer side of the front end surface side of the front inner housing 12, and an end on the rear end surface side of the front inner housing 12 is formed. A cutout for fitting the inside of the end portion of the rear casing 13 on the front end face side is formed on the outer side.

  The rear housing 13 is provided with a rear housing body 13a having a cylindrical shape as a whole, and an end surface on the front end surface side of the rear housing body 13a, and functions as a ground electrode layer of the piezoelectric element group 16 13b. Here, the rear casing body 13a has a front stage 131 that is set to have a diameter slightly larger than the inner diameter of the front outer casing 11 on the front end face side, and an outer diameter of the front outer casing 11 on the back side of the front stage 131. And a rear stage 132 set to have substantially the same outer diameter. The ground electrode layer 13b described above is formed on the front side end face of the front stage 131 of the rear casing body 13a over substantially the entire circumference. Thereby, the front stage part 131 of the rear housing body 13a can be fitted into a recess formed on the rear end face side of the front outer housing 11 and the front inner housing 12. In addition, the front stage portion 131 and the rear stage portion 132 of the rear housing body 13a are formed with one through hole 13c that is parallel to the center line direction and penetrates the rear housing body 13a.

  The ground electrode layer 13b provided in the rear casing 13 is configured by laminating a single conductive metal thin film or a plurality of layers on the rear casing main body 13a. As such a ground electrode layer 13b, an inner layer using, for example, Ti as an adhesion reinforcing layer is laminated on the rear casing body 13a, and an intermediate layer using, for example, Pt as a diffusion preventing layer is laminated on the inner layer, For example, a bonding layer using Au, for example, may be laminated on the uppermost layer above the intermediate layer.

  Here, since the front outer casing 11, the front inner casing 12, and the rear casing 13 are located at a position facing the combustion chamber C or in the vicinity of the combustion chamber C and become high temperature, at least −40 ° C. to 350 ° C. It is desirable to use a material that can withstand the operating temperature environment. In the present embodiment, as will be described later, the ground electrode of the piezoelectric element group 16 constituting the pressure detection unit 10 is used. In this case, since it is welded to a functional component such as an injector, it is desirable to manufacture using a conductive metal material. Specifically, a stainless steel material having high heat resistance and conductivity, for example, JIS standard SUS630, SUS316, SUS430, or the like may be used.

  Next, laser welding is performed over the entire circumference in a state where the end portion on the rear end face side of the front outer casing 11 is fitted into a notch provided on the outer end section on the front end face side of the rear casing main body 13a. Fixed. In addition, the end on the rear end surface side of the front inner housing 12 is fixed by laser welding over the entire circumference with a protrusion provided on the inner side of the front end surface side of the rear housing body 13a. Is done. In laser welding, the welding surface can be reliably sealed by performing welding continuously over one round, and the sealing performance and mounting strength can be enhanced.

  As shown in FIGS. 5 and 6, the pressure receiving ring 14 is provided so as to close a ring-shaped space formed on the front end face side by the front outer casing 11 and the front inner casing 12 that are concentrically arranged. . The pressure receiving ring 14 is exposed to the combustion chamber C to transmit the pressure received by the pressure receiving portion 14a receiving the combustion pressure from the combustion chamber and the pressure receiving portion 14a on the back side of the pressure receiving portion 14a to the pressure transmission ring 15. The transmission part 14b is integrated and configured.

  Further, the outer end portion of the pressure receiving portion 14a of the pressure receiving ring 14 is fixed by being laser-welded over the entire circumference in a state where the outer end portion of the pressure receiving portion 14 is fitted into a notch provided inside the front end surface side of the front outer casing 11. Is done. Further, the inner end portion of the pressure receiving portion 14a of the pressure receiving ring 14 is fixed by being laser welded over the entire circumference in a state where the inner end portion of the pressure receiving portion 14 is fitted in a notch provided outside the front end portion of the front inner housing 12. The In laser welding, the welding surface can be sealed by performing welding continuously over one round. As a result, the inner space 10b surrounded by the front outer casing 11, the front inner casing 12, the rear casing 13, and the pressure receiving ring 14 can seal all the joints except the through hole 13c.

  Further, the transmission portion 14b provided in the pressure receiving ring 14 is positioned with respect to both of the inner peripheral surface of the front outer casing 11 and the outer peripheral surface of the front inner casing 12 so as not to contact both. Note that the material constituting the pressure receiving ring 14 is made of an alloy having high elasticity and excellent durability, heat resistance, and corrosion resistance in consideration of exposure to the combustion chamber C at a high temperature and a high pressure. For example, SUH660 or the like may be used.

  6 to 8, the pressure transmission ring 15 described above is provided on the pressure transmission ring main body 15a having an annular shape and the end surface on the rear end surface side of the pressure transmission ring main body 15a. Output electrode layer 15b functioning as an output electrode for outputting a charge signal from the output electrode layer 15b. The output electrode layer 15b is formed over the entire end surface of the pressure transmission ring body 15a on the rear end surface side.

  Here, the cross section of the pressure transmission ring main body 15a is rectangular, the outer diameter of the pressure transmission ring main body 15a is smaller than the inner diameter of the front outer casing 11, and the inner diameter of the pressure transmission ring main body 15a is outside the front inner casing 12. It is larger than the diameter. In the present embodiment, the pressure transmission ring body 15a is made of a ceramic material such as alumina having heat resistance and insulation.

  The output electrode layer 15b provided on the pressure transmission ring 15 is configured by laminating a single conductive metal thin film or a plurality of layers on the pressure transmission ring main body 15a. As such an output electrode layer 15b, for example, an inner layer using Ti as an adhesion strengthening layer is stacked on the pressure transmission ring body 15a, and an intermediate layer using, for example, Pt as a diffusion preventing layer is stacked on the inner layer, For example, a bonding layer using Au, for example, may be laminated on the uppermost layer above the intermediate layer. Further, as the output electrode layer 15b, an alignment adjustment layer for adjusting the alignment of the piezoelectric element group 16 that further includes, for example, Au—Sn may be formed on the bonding layer.

  Next, the piezoelectric element group 16 will be described with reference to FIGS. 7A, 7B, and 8. FIG. 7A is an enlarged view of a T portion in FIG. 6, FIG. 7B is an enlarged view of a U portion in FIG. 6, and FIG. 8 is a cross-sectional view taken along line VV in FIG. 7 and 8, the piezoelectric element group 16 includes a first piezoelectric element 16 to a sixth piezoelectric element 16. Here, the first piezoelectric element 61 to the sixth piezoelectric element 16 have a common configuration, and each is formed on a piezoelectric body 16a processed into a rectangular parallelepiped shape and an end face of the piezoelectric body 16a on the front end face side. The front side electrode 16b and the rear side electrode 16c formed on the end face on the rear end face side of the piezoelectric body 16a are provided.

  The piezoelectric element 16 uses a piezoelectric body that exhibits the piezoelectric action of the piezoelectric longitudinal effect. The piezoelectric longitudinal effect refers to the action of generating charges on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis in the same direction as the charge generation axis of the piezoelectric body. The piezoelectric element 16 according to the present embodiment is housed in the internal space 10b of each housing so that the center line direction is the direction of the stress application axis. The piezoelectric element 16 may be configured using a piezoelectric lateral effect. The piezoelectric transverse effect is an action in which charges are generated on the surface of the piezoelectric body in the direction of the charge generation axis when an external force is applied to the stress application axis at a position orthogonal to the charge generation axis of the piezoelectric body. A plurality of piezoelectric bodies formed in a thin plate shape may be laminated, and by laminating in this way, it is possible to efficiently collect charges generated in the piezoelectric bodies and increase the sensitivity of the sensor.

  Further, as the piezoelectric body, a langasite crystal (a langasite, langagate, langanite, LGTA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, quartz, gallium phosphate, or the like may be used. In the piezoelectric element 10 of the present embodiment, a langasite single crystal is used as the piezoelectric body.

  On the other hand, the front-side electrode 16b and the rear-side electrode 16c are configured by laminating a single layer or a plurality of layers of highly conductive metal thin films on the end face on the front end face side and the end face on the rear end face side of the piezoelectric body 16a. . As such a front side electrode 16b and a rear side electrode 16c, an inner layer using, for example, Ti as an adhesion reinforcing layer is laminated on the piezoelectric body 16a, and an intermediate layer using, for example, Pt as a diffusion preventing layer is formed on the inner layer. For example, a bonding layer using Au, for example, may be stacked on the uppermost layer that is above the intermediate layer.

  In each of the first piezoelectric element 16 to the sixth piezoelectric element 16, each front-side electrode 16 b is in contact with an output electrode layer 15 b provided on the pressure transmission ring 15, and each rear-side electrode 16 c is connected to the rear housing 13. It contacts with the provided ground electrode layer 13b. In the present embodiment, the first to sixth piezoelectric elements 16 to 16 are joined to the output electrode layer 15b via the front electrodes 16b, and the pressure transmission ring 15 and the piezoelectric element group 16 are connected to each other. It has an integrated configuration. Furthermore, the piezoelectric function added as the plurality of piezoelectric element groups 16 is provided.

  Next, the configuration of the transmission unit 50 will be described with reference to FIGS. 6, 7A, and 7B. In FIG. 7B, the transmission unit 50 is provided with a transmission wire 51 that transmits a charge signal from the pressure detection unit 10 toward the injector 7, a front side of the transmission wire 51, and the pressure transmission of the pressure detection unit 10. A connection terminal 52 electrically connected to the output electrode layer 15b provided on the ring 15, and a front end face side of the transmission wire 51 and a rear end face side of the connection terminal 52. And a connection pipe 53 that electrically connects the terminal 52. In the transmission unit 50, the outer periphery of the transmission wire 51 and the outer peripheral surface of the connection pipe 53 are covered with an O-ring 57a and an O-ring 57b. The O-ring 57a is configured to seal the connection terminal 52 side on the pressure detection unit 10 side, and the O-ring 57b is configured to seal the transmission wire 51 on the injector 7 side. Furthermore, the rear end surface side of the transmission wire 51 is connected to the electrical connector portion 70 of the injector 7.

  The connection terminal 52 is formed of a metal rod-like body having heat resistance and conductivity, and an abutting portion 52a in which an end portion on the front end face side abuts against the output electrode layer 15b provided on the pressure transmission ring 15, The columnar part 52b located on the rear side of the abutting part 52a and the connection part 52c located further on the rear side of the columnar part 52b are integrally formed. The outer diameter of the abutting portion 52a of the connection terminal 52 is smaller than the radial gap in the internal space 10b of the housing, and the outer diameter of the columnar portion 52b is smaller than the outer diameter of the abutting portion 52a. The outer diameter of the part 52c is smaller than the outer diameter of the columnar part 52b.

  The connection pipe 53 is formed of a metal cylindrical body having heat resistance and conductivity, and the inner diameter of the through hole provided in the connection pipe 53 is the outer diameter of the conductor portion 51a in the transmission wire 51 and the connection terminal. 52 is larger than the outer diameter of the connecting portion 52c. The connection pipe 53 includes an end portion of the conductor portion 51a of the transmission wire 51 from the rear end surface side of the signal hole and a rear end of the connection portion 52c of the connection terminal 52 from the front end surface side of the through hole 13c. In this state, the connection pipe 53 is caulked from the outer peripheral surface side, so that the connection pipe 53 electrically connects the conductor 51a and the connection terminal 52 and is fixed. To do.

  The positioning tube 55 is composed of a cylindrical body made of alumina ceramic, and includes a front side cylindrical part 55a located on the front end surface side and a rear side cylindrical part 55b located on the rear side of the front side cylindrical part 55a. And have. Here, the outer diameter of the front side cylindrical part 55a in the positioning tube 55 is larger than the outer diameter of the rear side cylindrical part 55b, and smaller than the length of the inner space 10b in the radial direction. Further, the inner diameter of the positioning tube 55 is larger than the outer diameter of the columnar portion 52 b of the connection terminal 52.

  The coil spring 56 is disposed between the rear end surface of the abutting portion 52 a of the connection terminal 52 and the front end surface of the front cylindrical portion 55 a of the positioning tube 55. Here, the coil spring 56 is made of a metal having heat resistance, the end portion on the front end surface side abuts on the rear end surface of the abutting portion 52a of the connection terminal 52, and the end portion on the rear end surface side is positioned on the positioning tube 55. It abuts against the front end face of the front cylindrical portion 55a. Further, the inner diameter of the coil spring 56 is slightly larger than the outer diameter of the columnar portion 52 b in the connection terminal 52.

  Further, the coil spring 56 is set in a compressed state than the original state. Here, since the positioning tube 55 is restricted from moving toward the rear end surface by the rear housing 13, the connection terminal 52 is pressed against the front end surface by the coil spring 56. As a result, the end surface on the front end surface side of the abutting portion 52 a of the connection terminal 52 is in pressure contact with the output electrode layer 15 b provided on the pressure transmission ring 15.

  The sealing portion 57 includes a front side O-ring 57a located at the rear end face side outlet of the through hole 13c of the rear housing 13 and a rear side O-ring 57b located at the inlet hole side on the injector 7 side. Both the front-side O-ring 57a and the rear-side O-ring 57b are made of PFA (fluorine resin). Further, the outer diameters of the front-side O-ring 57a and the rear-side O-ring 57b are set larger than the inner diameters of the through holes 13c provided in the rear housing 13 or the signal wire guide holes provided in the injector, The inner diameters of the front-side O-ring 57 a and the rear-side O-ring 57 b are set smaller than the columnar portion 52 b of the connection terminal 52 or the outer diameter of the covering portion of the transmission wire 51.

  As a result, both the front-side O-ring 57a and the rear-side O-ring 57b after being mounted are compressed in the radial direction, and the front-side O-ring 57a is connected to the columnar portion 52b of the connection terminal 52 and the through hole of the rear housing 13. 13 c is sealed, and the rear O-ring 57 b is sealed between the outer diameter of the transmission wire 51 and the signal wire guide hole provided in the injector 7. By using PFA as the material of the O-ring 57a and the O-ring 57b, the connection terminal 52 and the transmission wire 51 are ensured to be slidable with respect to the sealing portion 57 (ring 57a and O-ring 57b). The end face on the front end face side of the abutting portion 52 a of the connection terminal 52 is in pressure contact with the output electrode layer 15 b provided on the pressure transmission ring 15 to be electrically connected.

  Next, a configuration in which the combustion pressure sensor 8A and the injector 7A according to the present embodiment are mounted will be described with reference to FIG. FIG. 6 shows a state where the combustion pressure sensor 8A is mounted on the outer peripheral surface of the tip end portion of the injector 7A. A step is provided at the tip of the injector 7A, and the inner peripheral surface of the combustion pressure sensor 8A is fitted to the step. In addition, a transmission unit 50 that transmits a signal from the pressure detection unit 10 of the combustion pressure sensor 8A extends toward the rear end surface, passes through a signal wire guide hole provided in the injector 7A, and the electric power of the injector 7A. It is configured to connect to the connector unit 70. At this time, the signal lines and the conductive holes are sealed by the sealing portions 57a and 57b.

  Next, with reference to FIG. 4, the situation where the inner peripheral surface and the outer peripheral surface of the combustion pressure sensor 8A are in contact with the outer peripheral surface of the tip portion of the injector 7A described above will be described. An alternate long and short dash line at the tip of the injector 7A indicates the outer peripheral surface h, and alternate long and short dash lines at the outer side and the inner side of the combustion pressure sensor 8A indicate the outer peripheral surface i and the inner peripheral surface j, respectively. Further, points P and Q on the outer peripheral surface h of the injector 7A indicate corners of the stepped portion on the outer peripheral surface, and points p on the outer peripheral surface i of the combustion pressure sensor 8A indicate corners of the outer peripheral surface. When the combustion pressure sensor 8A is inserted into the distal end portion of the injector 7A, the corner portion P of the injector 7A and the corner portion p of the outer peripheral portion of the combustion pressure sensor 8 are in contact with each other. At the same time, the corner Q of the outer peripheral portion of the injector 7 </ b> A is in contact with the inner peripheral surface j of the combustion pressure sensor 8.

  In FIG. 6, the point where these two points contact each other is a seal portion, and the seal portion is indicated by a “●” mark. These two seal portions are laser-welded over one circumference (welding 1, welding 2). In laser welding, a welding surface can be sealed by performing welding continuously over one round. Thereby, in a state where the combustion pressure sensor 8A is attached to the injector 7A, it is possible to prevent the high-pressure mixed gas or combustion gas generated in the combustion chamber C from leaking into the inside from the two welded portions, and the signal line It is possible to prevent leakage into the internal space 10b of the guide hole or the pressure detection unit. With the configuration described above, it is possible to obtain the injector unit 6A in which the burning pressure sensor is integrated.

  Next, the electrical configuration and operation of the injector unit 6A will be described with reference to FIGS. 1 and 6 to 8. First, the end surfaces on the rear end surface side of the respective piezoelectric bodies 16a provided in the first to sixth piezoelectric elements 16 to 16 constituting the piezoelectric element group 16 are connected to the rear side electrodes 16c provided on the rear side electrodes 16c. It is electrically connected to a ground electrode layer 13 b provided in the housing 13. Thereby, the rear side electrode 16c of the piezoelectric element group 16 is electrically connected to the rear casing body 13a constituting the rear casing 13 and grounded.

  On the other hand, the end faces of the piezoelectric bodies 16a provided on the front end face sides of the first to sixth piezoelectric elements 16 to 16 constituting the piezoelectric element group 16 are pressure-bonded via the front-side electrodes 16b provided respectively. It is electrically connected to the output electrode layer 15 b provided on the transmission ring 15. Thereby, each front side electrode 16b of the piezoelectric element group 16 is electrically connected on the output electrode layer 15b formed in a ring shape on the surface on the rear end face side of the pressure transmission ring 15.

  Further, the output electrode layer 15 b provided on the pressure transmission ring 15 is electrically connected to the connection terminal 52 by the spring pressure of the coil spring 56 via the abutting portion 52 a of the connection terminal 52. Furthermore, the connection terminal 52 is electrically connected to the conductor portion 51a in the transmission wire 51 through the connection pipe 53 from the connection portion 52c.

  Then, a charge signal transmission path from the connection terminal 52 to the conductor portion 51a via the connection pipe 53, and a connection portion (not shown) of the electric connector portion 70 of the injector 7 via the transmission wire 51 from the conductor portion 51a. ), The front outer case 11 made of metal, the front tube 11 made of metal by the positioning tube 55, the sealing portion 57, and the resin insulation layer 51b of the transmission wire 51, each made of an insulator. It is electrically insulated from the inner casing 12 and the rear casing 13.

  The injector unit 6A configured as described above has an outer peripheral portion of the injector 7A at least in the communication hole 4a provided in the cylinder head 4 when the injector unit 7A is attached to the cylinder head 4 of the internal combustion engine 1 shown in FIG. The flange portion 6C provided in the cylinder is clamped and fixed to the end face of the third hole portion 4c provided in the communication hole 4e, thereby being electrically connected to the cylinder head and grounded to the vehicle body.

  When the internal combustion engine 1 operates, the combustion pressure generated in the combustion chamber C acts on the pressure receiving ring 14 at the tip of the combustion pressure sensor 8A, acts on each piezoelectric element group 16 via the pressure transmission ring 15, and burns. A charge corresponding to the pressure is generated. The electric charge generated in each piezoelectric body 16a constituting the first to sixth piezoelectric elements 16 to the pressure transmitting ring 15 from the end face on the front end face side of each piezoelectric body 16a via each front side electrode 16b. It is transmitted to the provided output electrode layer 15b. Then, the charge signal transmitted to the output electrode layer 15 b is transmitted from the press-connecting connection terminal 52 to the conductor portion 51 a of the transmission wire 51 through the connection pipe 53. Then, the charge signal transmitted to the conductor part 51a is supplied to the signal processing part 100 via the electrical connector part 70 of the injector 7A. The charge signal supplied to the signal processing unit 100 is amplified and a voltage corresponding to the charge is supplied to the control device 200. Thereby, the control apparatus 200 performs predetermined control according to a combustion pressure with respect to functional components, such as the injector 7A which comprises the injector 6A.

  According to the first embodiment of the present invention, the following effects can be obtained.

  First, in a state where a ring-shaped combustion pressure sensor is mounted on the outer peripheral surface of the tip of the injector, two seal portions provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the injector are sealed by welding. As a result, the gap between the functional component and the combustion pressure sensor can be sealed, and in addition, the combustion pressure sensor can be reliably attached (fixed) to the injector. Accordingly, it is possible to provide a highly reliable injector unit with a combustion pressure sensor for an internal combustion engine that prevents the mixed gas and combustion gas from leaking to the outside of the detection element section and the cylinder head through the signal hole. .

  Second, since the combustion pressure sensor is fixed to the tip of the injector by welding, the detection performance is not affected even if the tightening load of the injector varies. In addition, there is no concern that the sensor unit is damaged due to excessive tightening.

  In the present embodiment, the piezoelectric element group 16 provided in the combustion pressure sensor 8A is composed of six piezoelectric elements. However, the present invention is not limited to this configuration, and a plurality of piezoelectric elements may be used. In this embodiment, the plurality of piezoelectric elements constituting the piezoelectric element group 16 are arranged at equal intervals in the circumferential direction. However, the present invention is not limited to this configuration, and may be non-equal intervals. Furthermore, in the present embodiment, the spacer group 17 is disposed between the piezoelectric element groups 16, but the present invention is not limited to this configuration, and the spacer group 17 may not be provided. In this embodiment, the signal processing unit 200 is provided outside the injector unit 6A. However, the signal processing unit 200 is not limited to such a form and may be provided inside. Furthermore, in the method of attaching the injector unit 6A to the cylinder head, the flange portion 6b of the injector unit 6A is clamped. However, the present invention is not limited to this configuration, and other portions may be clamped.

Second embodiment

  Next, the structure of the injector unit 6B of 2nd Embodiment is demonstrated using FIG. FIG. 9 is a cross-sectional view of an injector unit 6B in which the combustion pressure sensor 8B of the second embodiment is mounted on the injector 7B. The combustion pressure sensor 8B according to the second embodiment is the same as the combustion pressure sensor 8A according to the first embodiment, in which one of the two seal portions is used as a gasket so that the combustion gas from the guide hole of the signal line can be obtained. Although the leakage is prevented, the other basic configuration is the same as that of the first embodiment, so the same elements and the same steps are denoted by the same reference numerals, and a part of overlapping description is omitted.

  In FIG. 9, when the combustion pressure sensor 8B is mounted on the outer periphery of the tip end of the injector 7B, a gap is provided on the contact surface X between the injector 7B and the combustion pressure sensor 8B. When the combustion pressure sensor 8B is pressed against the injector 7B in the direction of the rear end surface, the combustion pressure sensor 8B is locked at the stepped portion Y provided on the inner peripheral surface, so that a predetermined gap is formed on the contact surface X. It is configured. Then, by inserting the ring-shaped gasket 61 that is slightly thicker than the gap of the contact surface X, the gasket 61 is compressed by a predetermined amount, and the contact surface X is sealed. On the other hand, the contact portion between the inner peripheral surface of the combustion pressure sensor 8B and the outer peripheral surface of the tip end portion of the injector 7B is fixed (welding 1) by laser welding. Thus, one of the two seal portions where the injector 7B and the combustion pressure sensor 8B are in contact is sealed with the gasket, and the other is sealed with welding. With the above configuration, the injector unit 6B is obtained.

  According to the second embodiment of the present invention, the following effects can be obtained.

  First, when a ring-shaped combustion pressure sensor is mounted on the outer peripheral surface of the tip of the injector, one of the two seal portions provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the injector is welded. Therefore, even when the other is sealed with a gasket, the gap between the injector and the combustion pressure sensor can be sealed. A highly reliable injector unit that prevents gas leakage can be provided.

  Secondly, as the sealing means, one uses welding and the other uses a gasket, thereby reducing the number of steps in the welding process. Thereby, manufacturing cost can be suppressed.

  The material of the gasket 61 may be made of metal or non-metal, and may be selected according to a required sealing level and provided with a predetermined heat resistance. Moreover, the cross-sectional shape of the gasket 61 should just have predetermined | prescribed elasticity and a predetermined sealing effect is acquired by compressing a predetermined amount.

Third embodiment

  Next, the configuration of the combustion pressure sensor 8C of the third embodiment will be described with reference to FIG. FIG. 10 is a cross-sectional view of an injector unit 6C in which the combustion pressure sensor 8C of the third embodiment is mounted on the injector 7C. Like the combustion pressure sensor 8B of the second embodiment, the combustion pressure sensor 8C of the third embodiment uses one of the two seal portions as a gasket to burn from the signal wire guide hole. Although gas leakage is prevented, the other basic configuration is the same as that of the second embodiment, and therefore, the same elements and the same steps are denoted by the same reference numerals, and a duplicate description is partially omitted.

  In FIG. 10, in a state where the combustion pressure sensor 8C is mounted on the outer periphery of the tip end portion of the injector 7C, a gap is provided in the stepped portion Y provided on the inner peripheral surface of the combustion pressure sensor 8C. When the combustion pressure sensor 8C is pressed against the injector 7C in the direction of the rear end face, a predetermined gap is formed in the stepped portion Y. Then, by inserting a ring-shaped gasket 62 that is slightly thicker than the gap of the stepped portion Y, the gasket 62 is compressed by a predetermined amount, and the stepped portion Y is sealed. That is, a step (Y) is formed on the inner peripheral surface of the combustion pressure sensor 8C, and a gasket is provided between the step (Y) and the step (second step) (Y) formed on the outer peripheral surface of the injector 7C. 62 is interposed. On the other hand, the contact portion between the outer peripheral surface of the combustion pressure sensor 8C and the outer peripheral surface of the tip end portion of the injector 7C is sealed by laser welding (welding 1). As a result, of the two seal portions where the injector 7C and the combustion pressure sensor 8C are in contact, the stepped portion is sealed by the gasket 62, and the other is sealed by welding. With the above configuration, an injector unit 6C is obtained.

  According to the sealing structure shown in the third embodiment of the present invention, the same effect as the sealing structure shown in the second embodiment can be obtained. As described above, the gasket may have a configuration in which a step portion is formed on the outer peripheral surface of the injector unit and is interposed between the step portion and the end surface of the combustion pressure sensor (second embodiment). A stepped portion (Y) may be formed on the inner peripheral surface side and interposed between the stepped portion (Y) and the second stepped portion (Y) formed on the outer peripheral surface of the injector unit. As described above, the gasket can be used on either the outer peripheral surface or the inner peripheral surface of the combustion pressure sensor, can flexibly cope with it, and can increase the degree of freedom in design.

Fourth embodiment

  Next, the configuration of the combustion pressure sensor 8D of the fourth embodiment will be described with reference to FIG. FIG. 11 is a cross-sectional view of an injector unit 6D in which the combustion pressure sensor 8D of the fourth embodiment is mounted on the injector 7D. The combustion pressure sensor 8D of the fourth embodiment is a position separated from the pressure detection unit by changing the position of the welding part located on the combustion chamber C side among the two welding parts in the combustion pressure sensor 8A of the first embodiment. , The generation of thermal distortion due to the welding heat of the front inner casing 12 (inner cylinder part) is suppressed. Since the other basic configuration is the same as that of the first embodiment, the same elements and steps are denoted by the same reference numerals, and a part of overlapping description is omitted.

  In FIG. 11, in a state where the combustion pressure sensor 8D is mounted on the outer periphery of the distal end portion of the injector 7D, the contact portion between the outer peripheral surface of the combustion pressure sensor 8D and the outer peripheral surface of the distal end portion of the injector 7D is fixed by welding (welding 1). . The front inner housing 12 of the combustion pressure sensor 8D is provided with a ring-shaped protrusion 12a on the inner peripheral surface, and a step is provided at the tip of the injector 7D in accordance with the ring-shaped protrusion 12a. Yes. The engaging portion between the tip of the ring-shaped protrusion 12a and the injector 7D is welded (welding 2). Thereby, two seal parts are sealed by welding. Thereby, a space between the injector and the combustion pressure sensor can be sealed, and leakage of the mixed gas and the combustion gas to the outside of the detection element portion and the cylinder head can be prevented through the signal wire guide hole. Moreover, generation | occurrence | production of the thermal distortion by the welding heat of the front inner side housing | casing 12 can be suppressed. With the above configuration, an injector unit 6D is obtained.

  According to the fourth embodiment of the present invention, the following effects can be obtained.

  When the ring-shaped combustion pressure sensor is mounted on the outer peripheral surface of the tip of the injector, the two seal portions provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the injector are sealed by welding, and the tip surface side The welded part of the ring is provided with a ring-shaped projection to place the welding position away from the detection part, thereby preventing leakage of mixed gas and combustion gas to the outside of the detection element part and the cylinder head through the lead hole of the signal line At the same time, it is possible to suppress the occurrence of thermal strain due to welding heat of the front inner housing 12 (inner cylinder portion), prevent deterioration of detection performance due to strain of the pressure detection portion 10, and provide an injector unit with excellent reliability. it can.

  In addition, although the ring-shaped protrusion part 12a provided in the internal peripheral surface of the front inner housing | casing 12 of combustion pressure sensor 8D made the cross-sectional shape rectangular, it is not limited to the form which concerns. The cross-sectional shape may be a trapezoidal shape as long as it can be easily welded to the injector unit. Furthermore, a gasket may be used for either one of the sealing portions as in the sealing configuration shown in the second embodiment.

Fifth embodiment

  Next, as a fifth embodiment, a configuration of a spark plug unit 5A in which a combustion pressure sensor 8A is mounted on a spark plug 5 which is one of functional parts will be described with reference to FIG. FIG. 12 is a cross-sectional view of the spark plug unit 5A. In the fifth embodiment, the basic configuration for mounting the combustion pressure sensor 8A on the outer peripheral surface of the tip of the spark plug 5 is the same as that for mounting on the injector 7 of the first embodiment. Are given the same numbers, and duplicate descriptions are omitted. Thereby, the spark plug unit 5A is obtained.

  According to the fifth embodiment of the present invention, the following effects can be obtained.

  First, in a configuration in which a ring-shaped combustion pressure sensor is applied to a spark plug, the outer peripheral surface of the combustion pressure sensor in contact with the outer peripheral surface of the tip of the spark plug and two seal portions provided on the inner peripheral surface are welded. By doing this (welding 1, welding 2), the gap between the spark plug and the combustion pressure sensor can be sealed, and the mixed gas and the combustion gas can be discharged to the outside of the detection element portion and the cylinder head through the signal wire guide hole. A spark plug unit that prevents leakage and has excellent reliability can be provided.

  Second, since the combustion pressure sensor is fixed by welding to the tip of the spark plug, even if the tightening load of the spark plug fluctuates, its detection performance is not affected. In addition, there is no concern that the sensor unit is damaged due to excessive tightening.

  In this embodiment, the two seal portions of the combustion pressure sensor and the spark plug are welded. However, the present invention is not limited to such a form. A sealing configuration similar to that shown in the second and third embodiments may be used, one using welding and the other using a gasket.

  Although various embodiments have been described in detail above, the present invention is not limited to such embodiments, and the detailed configuration, shape, material, quantity, and the like are within the scope that does not depart from the spirit of the present invention. , Can be changed, added and deleted arbitrarily. For example, in each embodiment of the present invention, the configuration targeting an injector or a spark plug as a functional component has been described, but the present invention is not limited to such a configuration. You may comprise and attach to functional parts other than the injector and spark plug attached to an internal combustion engine. Moreover, in the attachment position of the combustion pressure sensor in each embodiment of this invention, although the front end surface of a functional component and the front end surface of a combustion pressure sensor are substantially corresponded, it is not limited to the form which concerns. The tip surfaces of the functional component and the combustion pressure sensor do not have to coincide with each other. Therefore, the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor for performing welding also include the edge portions (boundary portions with the end surfaces) of the outer peripheral surface and the inner peripheral surface. As described above, if the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor to be welded include the edge portions of the outer peripheral surface and the inner peripheral surface, the tip of the outer peripheral surface of the functional component is the inner peripheral surface of the combustion pressure sensor. Even if it is a form (refer FIG. 12) located ahead of the front-end | tip of this, it can fix reliably by combining the edge part and end surface of the internal peripheral surface in a combustion pressure sensor.

  The functional component unit with a combustion pressure sensor for an internal combustion engine according to the present invention can be used for measuring the pressure in the combustion chamber of the engine, particularly when detecting the combustion pressure by attaching it to the outer periphery of the tip of a spark plug, an injector or the like. it can.

Claims (12)

In the functional component unit for detecting the internal pressure of the combustion chamber by mounting a combustion pressure sensor configured in a ring shape on the outer peripheral surface of the tip of the functional component attached to the combustion chamber of the internal combustion engine,
The combustion pressure sensor includes a housing unit composed of an outer cylinder part constituting an outer peripheral surface and an inner cylinder part constituting an inner peripheral surface, and a pressure receiving surface provided in front of the housing unit on the combustion chamber side and having a front surface as a pressure receiving surface A ring block portion, a piezoelectric element that is disposed in the housing unit and detects pressure from the pressure-receiving ring block portion, and a support ring block portion that is provided behind the housing unit and supports the piezoelectric element,
The combustion pressure that is in contact with the functional component when the thickness of the inner cylindrical portion is selected to be greater than the thickness of the outer cylindrical portion and the combustion pressure sensor is mounted on the outer peripheral surface of the tip end portion of the functional component. A functional component unit with a combustion pressure sensor for an internal combustion engine, wherein sealing means is provided on each of an outer peripheral surface of the sensor and an inner peripheral surface of the combustion pressure sensor in contact with the functional component.   2. The functional component unit with a combustion pressure sensor for an internal combustion engine according to claim 1, wherein sealing means provided on each of an outer peripheral surface and an inner peripheral surface of the combustion pressure sensor in contact with the functional component is welding.   The functional part unit with a combustion pressure sensor for an internal combustion engine according to claim 2, wherein the welding uses laser welding and is continuously welded over one round.   4. The combustion pressure sensor for an internal combustion engine according to claim 2, wherein the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor for performing the welding include edge portions of the outer peripheral surface and the inner peripheral surface. Functional component unit.   The functional part unit with a combustion pressure sensor for an internal combustion engine according to claim 1, wherein the support ring block part has a stepped part that engages with an outer peripheral surface of the functional part on an inner peripheral surface.   A stepped portion is provided between the outer peripheral surface of the functional component and the inner peripheral surface of the combustion pressure sensor by forming a ring-shaped protrusion that protrudes in the center direction from the inner peripheral surface of the combustion pressure sensor. The functional component unit with a combustion pressure sensor for an internal combustion engine according to any one of claims 2 to 5, wherein the tip of the portion and the outer peripheral surface of the functional component are welded.   2. The combustion pressure for an internal combustion engine according to claim 1, wherein one of the sealing means provided on the outer peripheral surface and the inner peripheral surface of the combustion pressure sensor in contact with the functional component is a weld and the other is a gasket. Functional component unit with sensor.   8. The functional part unit with a combustion pressure sensor for an internal combustion engine according to claim 7, wherein the gasket is made of a metal or non-metal having a predetermined thickness and elasticity, and is formed in a ring shape as a whole.   9. A combustion pressure sensor for an internal combustion engine according to claim 5, wherein a step portion is formed on an outer peripheral surface of the functional component, and the gasket is interposed between the step portion and an end surface of the combustion pressure sensor. With functional parts.   8. A step portion is formed on an inner peripheral surface of the combustion pressure sensor, and the gasket is interposed between the step portion and a second step portion formed on the outer peripheral surface of the functional component. Or a functional component unit with a combustion pressure sensor for an internal combustion engine according to claim 8;   The functional component unit with a combustion pressure sensor for an internal combustion engine according to any one of claims 1 to 10, wherein the functional component is an injector that injects fuel into a combustion chamber.   The functional component unit with a combustion pressure sensor for an internal combustion engine according to any one of claims 1 to 10, wherein the functional component is a spark plug that ignites an air-fuel mixture in a combustion chamber.

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