JPS5934416A - Preheating apparatus - Google Patents

Abstract

PURPOSE:To obtain a preheating apparatus provided with the superior combustion performance in which a glow plug is not needed and with which a smoth vortex flow is formed, by constituting a fuel injection nozzle and a heat generating member in an integral structure and combusting the jetted fuel at one position in a combustion chamber such as whirl chamber. CONSTITUTION:A heat-resistive metal holder 5 is installed onto a fuel injection nozzle 3 so as to cover said nozzle, and a sheathed heater 7 equipped with a conduction electrode 8 is projected from the peripheral edge surface of a fuel jetting-out hole 6 so that the top edge of the heater is directed to the direction of fuel injection, and the fuel injection nozzle 3 and he sheathed heater 7 are constituted in an integral structure. The above-described device is installed into a whirl chamber 1, and the fuel jetted-out from the fuel injection nozzle 3 is combusted immediately before the outlet of the jetting-out hole 6. Therefore, ignition lag is prevented because ignition is carried-out immediately before the outlet of the fuel jetting-out hole, and the smooth vortex flow is formed in the combustion chamber because a projection part such as glow plug does not exist in the combustion chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition assist preheating device used primarily for starting a diesel engine.

Conventional starting aids for diesel engines include coil-type, sheath-type, etc. glow plugs installed in the auxiliary combustion chamber, etc. When starting, the plug is energized and becomes red hot, preheating the fuel in the combustion chamber and facilitating starting. There are known ways to do this.

However, while the use of glow plugs is extremely effective for starting in cold weather, there is the problem that their presence in the combustion chamber affects combustibility during normal operation after startup or during idling. Ta.

That is, especially in the case of a vortex chamber type as shown in FIG. 1, air flowing into the vortex chamber 1 through the communication hole 2 creates a vortex in the chamber during the compression process after startup.

Since the fuel mixture is injected from the fuel injection nozzle 3 and preheated by the glow plug to completely burn the air-fuel mixture, the heating element 4 of the glow plug protrudes into the swirl chamber 1. After starting, this becomes an obstacle and obstructs the smooth vortex flow, resulting in a reduction in engine output, deterioration in fuel efficiency, an increase in harmful exhaust gas, and other problems that adversely affect engine performance.

The present invention was made in view of the above situation, and by integrating the fuel injection nozzle and the heat generating member, the injected fuel is combusted in one place in the combustion chamber such as the swirl chamber, which is different from the conventional method. It is an object of the present invention to provide a preheating device with excellent combustibility and smooth formation of a vortex flow, which does not require the provision of a glow plug in a room other than a fuel injection nozzle.

The details of the present invention will be explained below using the accompanying drawings. FIGS. 2 and 6 show an embodiment of the preheating device of the present invention. (In the figures, the same parts as in FIG. 1 are designated by the same reference numerals.) FIG. 2 is a longitudinal section of the main part, and FIG. The figure shows how it is attached to the swirl chamber.

That is, in the preheating device of the present invention, as shown in FIG. 2, a holder 5 made of heat-resistant metal is provided around the fuel injection nozzle 3 so as to cover the periphery thereof, and the metal holder 5 is inserted through the fuel injection nozzle 3.
From the peripheral end surface of the fuel nozzle hole 6 of the open end forming the
A sheathed heater T having a current-carrying electrode 8 is protruded so that its tip faces in the fuel injection direction, and the fuel injection nozzle 3 and the sheathed heater 7 are integrated, as shown in Figure 6. It is installed in the swirl chamber 1 and the fuel injected from the fuel injection nozzle 3 is combusted just before the outlet of the nozzle hole 6. Although FIGS. 2 and 6 show an example in which one or more sheathed heaters 7 are attached to the metal holder 5, the number of sheathed heaters that can be attached does not necessarily have to be one.
The number is not limited to one, but a plurality may be provided surrounding the fuel injection hole 6. Further, the sheathed heater 7 may be formed in a ring shape as shown in FIG. O.D. 2.5~3.0
A wII heat-resistant wire coil is used that is embedded in a heat-resistant insulator that is crimped into a heat-resistant metal tube.

As can be understood from the above, the preheating device of the present invention configured as described above is a metal preheating device having an open end that surrounds a fuel injection nozzle installed in a combustion chamber such as a swirl chamber and forms a fuel injection hole. A holder is provided, and a sheathed heater is provided as a heat generating member with its tip facing the fuel injection direction from an end surface around the nozzle hole of the metal holder, thereby creating a structure in which the fuel injection nozzle and the heat generating member are integrated. Because the injected fuel is ignited just before the exit of the fuel nozzle, there is no ignition delay and the ignitability is extremely good.In addition, there is no large protrusion inside the combustion chamber like the conventional glow plug. The vortex flow inside the room becomes smoother, eliminating factors that impede engine performance such as a decrease in engine output and deterioration of fuel efficiency due to ignition errors after starting, and an increase in harmful exhaust gases. Since there is no need to provide a mounting hole for the glow plug separately from the injection nozzle, the vortex chamber etc. can be made into a vertical structure, and the number of man-hours required for installing the glow plug can also be omitted. Accordingly, it is possible to provide a preheating device for starting assistance.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing how a conventional preheating device is attached to the swirl chamber, Fig. 2 is a longitudinal cross-sectional view showing the main parts of the preheating device of the present invention, and Fig. 3 is a vertical cross-sectional view showing the preheating device of the present invention installed in the swirl chamber. FIG. 4 is a longitudinal sectional view showing the attached state of the heater, and FIG. 4 is a perspective view showing another embodiment of the sheathed heater. 1... Vortex chamber, 2... Communication hole, 3... Fuel injection nozzle, 4... Glow plug, 5... Metal holder, 6... Nozzle hole 7... Sheathed heater, 8...electrode. Agent Patent Attorney Mamoru Takeuchi

Claims (1)

[Claims] A preheating device in which a heat generating member is disposed near a fuel injection nozzle in a combustion chamber or a sub-combustion chamber of a cylinder head,
A metal holder having an open end that forms a fuel injection hole is provided to cover the periphery of the fuel injection nozzle, and the metal holder is inserted into the metal holder so that the metal holder is inserted into the metal holder and extends from the tip surface surrounding the injection hole toward the fuel injection direction of the fuel injection nozzle. A sheathed heater is provided as a heat generating member. A preheating device characterized by integrating a fuel injection nozzle and a heat generating member.