JPH0421016Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to an ignition timing sensor for an internal combustion engine,
In particular, a light guide rod consisting of a light guide arranged such that its tip faces into the engine combustion chamber, a cylindrical case that holds the light guide rod while shielding the combustion chamber from the outside air, and a rear end of the light guide rod. an ignition timing sensor for an internal combustion engine, the ignition timing sensor having a light detection section disposed facing the light guide rod, and detecting the ignition timing from the state of combustion light guided by the light guide rod via the light detection section. Regarding the improvement of

[Conventional technology]

In recent years, improvements in output, fuel efficiency, or exhaust gas purification performance have become important issues, particularly in automobile diesel engines and gasoline engines. As one means to achieve this, when controlling the fuel injection timing, an ignition timing sensor is provided to detect combustion light in the engine combustion chamber, and the ignition timing is detected from the output of the ignition timing sensor. Accordingly, it has been proposed, for example, to perform feedback control on timing control valves. When detecting the ignition timing in such fuel injection timing control, as a means for extracting the state of combustion light from the engine combustion chamber to the outside, for example, a light guide rod made of an optical fiber or a quartz glass rod is used to guide the light inside the combustion chamber. It is conceivable to attach and hold it to the engine's cylinder head, etc., in a state where it is isolated from the outside air. In this case, the light guide rod is held within a cylindrical case made of a heat-resistant material, and the case is screwed into a screw hole formed in the cylinder head of the engine. Here, the combustion light in the engine combustion chamber taken out through this light guide rod is transmitted to a light receiving element mounted facing the rear end of the light guide rod, or via an optical fiber, to a light receiving element disposed at a distance. The light is received by a light receiving element, where it is converted into an electrical signal. The cylindrical case for holding the light guide rod is generally made of metal, and on the other hand, as the light guide rod is made of quartz glass as described above, both have a large coefficient of thermal expansion. different. Therefore, in the past, in order to reduce the distortion caused by the different coefficients of thermal expansion, a considerable gap was provided between the inner periphery of the cylindrical case and the outer periphery of the light guiding rod. However, the pressure inside the combustion chamber of the engine is high, and in the case of a diesel engine in particular, the pressure inside the combustion chamber is higher than that of a gasoline engine. A problem arises in that it is easy to infiltrate. This can be countered to some extent by narrowing the gap, but if the gap is narrowed, the thermal distortion described above will occur, so conventionally,
It was not possible to obtain the optimum distance between the light guide rod and the cylindrical case.

[Problem that the invention attempts to solve]

This invention was made in view of the above-mentioned conventional problems, and provides an ignition timing sensor for an internal combustion engine that can prevent gas from entering the combustion chamber without causing thermal distortion of the light guiding rod. The purpose is to

[Means to solve the problem]

This invention consists of a light guide rod consisting of a light guide whose tip faces into the engine combustion chamber, a cylindrical case that holds the light guide rod while shielding the combustion chamber from the outside air, and a light detection unit that detects output light from the rear end, and detects the ignition timing of the internal combustion engine from the state of the combustion light guided by the light guide rod via the light receiving element. In the sensor, a multi-porous member is disposed on at least the outer periphery of the tip of the light guiding rod and the inner circumferential surface of the cylindrical case, in contact with the outer periphery of the light guiding rod and the inner periphery of the cylindrical case, and The above object is achieved by holding the light guiding rod within the cylindrical case via a flexible member.

[Effect]

In this invention, the light guiding rod is held within the cylindrical case via a multi-porous member, thereby absorbing the difference in thermal expansion between the cylindrical case and the light guiding rod, and absorbing both from the combustion chamber. It is possible to prevent combustion gas from entering between the two.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the ignition timing sensor of the present invention is applied to a diesel engine will be described in detail below with reference to the drawings. In this embodiment, as shown in FIG. 1, an ignition timing sensor 12 is inserted and fixed into a cylinder head 10B of a diesel engine 10 for detecting combustion light in a combustion chamber 10A of a diesel engine 10.
and detecting the ignition timing by processing the output of the ignition timing sensor 12 inputted via the lead wire 16,
The engine includes an electronic control unit (hereinafter referred to as ECU) 20 that controls, for example, fuel injection timing in accordance with the detected ignition timing. In Figure 1,
22 is a fuel injection nozzle, 24 is a glow plug, and 26 is a piston. As shown in detail in FIG. 2, the ignition timing sensor 12 includes a light guide rod 30 made of, for example, a quartz glass light guide, which is arranged so that its tip 30A faces into the engine combustion chamber 10A, and a light guide rod 30 that is made of, for example, a quartz glass light guide. A cylindrical case 32 made of highly heat-resistant metal or ceramics holds the light guide rod 30 in a state where the inside is shielded from the outside air, and a cylindrical case 32 is arranged facing the rear end 30B of the light guide rod 30, and the light guide rod 30 is It has a light receiving element 34 made of, for example, a silicon phototransistor, for receiving the combustion light guided by the light guide rod 30 and converting it into an electric signal, and the state of the combustion light guided by the light guide rod 30. The ignition timing is detected from the light receiving element 34, and the tip end of the light guide rod 30 is welded to the inner periphery of the tip of the cylindrical case 32 to form a part of the cylindrical case 32. A porous or fibrous material that is covered up to the tip by the tube 32A constituting the light guide rod 30, thereby forming a stopper in the tip direction, and that is in contact with the outer periphery of the tip of the light guide rod 30 and the inner periphery of the tube 32A. A light guiding rod 30 is held through a multi-hollow member 33 made of material. Here, the tube 32A and the light guiding rod 30
The distance between them should be 0.5 to 1.5 mm on each side. a cylindrical case 32 that holds the light guiding rod 30;
A through hole 42 is formed coaxially and continuously with the tube 32 through the center of the cylindrical case 32. The distal end portion of the light guide rod 30 is inserted into the through hole 42 with a portion protruding from the distal end of the cylindrical case 32.
It is inserted and held inside. A portion of the distal end of the light guide rod 30 protruding from the cylindrical case 32 is covered and protected by the tube 32A. The positioning of the light guide rod 30 in the rear end direction and the prevention of its removal are performed using the adapter 4 that contacts the outer peripheral portion of the rear end 30B.
This is done by being pressed down by the tip of 8. The adapter 48 is attached and fixed to the rear end of the cylindrical case 32 by caulking. The adapter 48 is a cylindrical member having a hollow chamber 50 containing the light receiving element 34, and the light receiving element 34 is supported by a substrate 52, which is connected to the hollow chamber 50 in the adapter 48.
It is positioned and held by being inserted from the rear end direction of the adapter and abutting against the inwardly projecting shoulder portion 54 of the adapter. An insulator 56 is provided on the rear end side of the board 52.
is arranged, and this insulator 56 is connected to the connector body 5 inserted from the rear end side of the adapter 48.
8, and thereby the substrate 52 is positioned and held in the axial direction of the light guide rod via the insulator 56. The connector body 58 is detachable from the mating connector body 59, and when the mating connector body 59 is inserted from the rear end side, the terminal 60 is electrically connected to the terminal of the mating connector body 59. It is something that This terminal 60 is connected to the insulator 56
The light receiving element 3 is inserted through the substrate 52 portion.
4 is connected to the lead wire 62 from the light receiving element 34.
is adapted to derive an electrical output signal. Reference numeral 58A in the figure is a large diameter portion of the connector body 58 formed at a position corresponding to the rear end of the adapter 48, and the large diameter portion 58A is fixed to the rear end of the adapter 48 by caulking. be done. Reference numeral 64 in the figure is an O-ring interposed between the connector body 58 and adapter 48 to seal the gap between the two, and 66 is an O-ring attached to the connector body 58 to seal the gap between the two when connected to the mating connector body 59. An O-ring 68 for connecting the connector body 58 to the mating connector body 59
The lock knobs that lock both devices when connected to each other are shown. Further, reference numeral 32B is a threaded portion for screwing the cylindrical case 32 onto the cylinder head 10B, and 32C is a threaded portion formed integrally with the cylindrical case 32, for screwing the cylindrical case 32 onto the cylinder head 10B. Or the hexagonal nut part used when unscrewing is shown. In this embodiment, the light guide rod 30 is held within a tube 32A that constitutes a part of the cylindrical case 32 via a porous or fibrous material 33 that is in direct contact with the light guiding rod 30. Because there are
When both of them are exposed to high heat, large thermal expansion occurs, and even if both have large coefficients of thermal expansion, the light guide rod 30 and the tube 32A are in direct contact with each other. The interposed multi-porous member 33 can absorb this difference in thermal expansion and prevent combustion gas from entering the engine combustion chamber 10A through the gap. Note that in the above embodiment, the polyporous member 33
is arranged only in the vicinity of the tip 30A of the light guide rod 30;
may be disposed at least in the vicinity of the tip 30A of the light guiding rod 30, and may therefore be disposed over the entire length of the outer periphery of the light guiding rod 30.

[Effect of the idea]

Since the present invention is constructed as described above, it has a simple structure, absorbs the difference in thermal expansion between the light guide rod and the cylindrical case, and ensures reliable operation without intrusion of combustion gas from the combustion chamber. It has an excellent effect of being able to hold the light guide rod.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the overall configuration of an ignition timing detection device in which an embodiment of the ignition timing sensor for a diesel engine according to the present invention is used, and FIG. 2 is a sectional view of the ignition timing sensor according to the embodiment. FIG. 3 is a cross-sectional view showing the configuration. 10... Diesel engine, 10A... Combustion chamber, 12... Ignition timing sensor, 30... Light guide rod, 30A... Tip, 30B... Rear end, 32...
Cylindrical case, 33...Multiple air mass chamber member, 34...
Light receiving element.

Claims (1)

[Scope of utility model registration request] A light guide rod consisting of a light guide arranged such that its tip faces into the engine combustion chamber, a cylindrical case that holds the light guide rod in a state where the combustion chamber is shielded from the outside air, and a light guide rod that extends from the rear end of the light guide rod. An ignition timing sensor for an internal combustion engine, comprising: a light detection section that detects output light, and detects ignition timing from the state of combustion light guided by the light guide rod via the light detection section; A multi-porous material is disposed between at least the outer periphery of the tip of the light guide rod and the inner periphery of the cylindrical case, in contact with the outer periphery of the light guide rod and the inner periphery of the cylindrical case, and the multi-porous material is An ignition timing sensor for an internal combustion engine, the light guiding rod being held within the cylindrical case.