JPH0223261A - Fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To improve cold startability of an auxiliary chamber type diesel engine by a method wherein during the cold starting of an engine, fuel is injected through an auxiliary injection port to the preheat device of an auxiliary combustion chamber. CONSTITUTION:In a diesel engine, an auxiliary combustion chamber 5 formed in a cylinder head 2 is communicated to a main combustion chamber, partitioned between the cylinder head 2 and a piston 3, through a communication hole 6. The cylinder head 2 is provided with a fuel injection valve 7 to inject fuel to the auxiliary combustion chamber 5 and a glow plug 8 serving as a preheat device. Further, in the fuel injection valve 7, a main injection port 9 and an auxiliary injection port 10 for the starting use only are formed. In this case, the auxiliary injection port 10 is disposed in a manner that the fuel injection direction thereof is pointed to the glow plug 8. An on-off valve 13 released only during cold starting is disposed in an auxiliary fuel passage 12 communicated to the auxiliary injection port 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection device for a pre-chamber diesel engine.

(Prior art) In addition to the main combustion chamber formed between the cylinder head and the piston, the DI 2 diesel engine is equipped with an auxiliary combustion chamber called an auxiliary combustion chamber (pre-combustion chamber or swirl chamber). There is a type C that communicates with the communication hole. When fuel is injected from the fuel injection valve into the auxiliary combustion chamber, a part of it burns and a pressure stop occurs, and unburned gas is vigorously injected into the main combustion chamber through the communication hole. It mixes with air and burns.

(Problem to be Solved by the Invention) By the way, such pre-combustion chamber type diesel engines have difficulty in starting, so generally the sub-combustion chamber is used as a preheating device to heat up red heat by supplying electricity during cold starting. A glow plug has been installed to improve starting performance. On the other hand, the direction of fuel injection from the fuel injection valve is
It is necessary to set it so as not to obstruct the swirl generated in the sub-combustion chamber. When the injection direction is set in this way, it is difficult to bring the fuel into good contact with the glow plug, which causes a problem of starting failure at the time of starting.

In view of the above problems, the present invention aims to improve starting performance of a diesel engine by injecting fuel toward a preheating device from an auxiliary injection port installed separately from the main injection port during startup. The object is to provide a fuel injection device in an engine.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a diesel engine equipped with a sub-combustion chamber, in which a main injection port and a sub-injection port for fuel are arranged side by side in the sub-combustion chamber, and The fuel injection direction of the sub-injection port is set to face the preheating device installed in the sub-combustion chamber, and a valve is installed in the fuel passage leading to the sub-injection port, which opens when cold and closes when warm. It is.

(Function) Therefore, when the engine is cold, the valve provided in the fuel passage of the sub-injection port is held open, so when the engine is started in this state, fuel flows from both the main injection port and the sub-injection port. Injected into the combustion chamber. At this time, since the fuel from the sub-injection port is sprayed toward the preheating device, the fuel comes into contact with the preheating device effectively. After the engine is warmed up, the valve closes to stop fuel injection from the a1 injection port, and fuel injection is performed only from the main injection port.

(Example) Hereinafter, an example of the present invention will be specifically described based on the drawings.

In FIG. 1, reference numeral 1 indicates a cylinder tab 1'', 2 a cylinder head, 3 a piston, and 4 a main combustion chamber formed between the piston 3 and the cylinder head 2. A sub-combustion chamber 5 is formed in the cylinder head 2, and the sub-combustion chamber 5 communicates with the main combustion chamber 4 via a communication hole 6 set to a predetermined thickness. The cylinder head 2 also includes a fuel injection valve 7 that injects fuel into the auxiliary combustion chamber 5, and a glow plug 8 that serves as a preheating device that becomes red hot when energized during a cold start.
is installed.

In such a pre-chamber type diesel engine, the fuel injection valve 7 is provided with two injection ports 9 and 10. That is, one is the main injection port 9, and the other is the sub injection port 10 dedicated for starting. The injection direction of the main injection port 9 is set in a direction that does not inhibit the generation of swirl in the sub-combustion chamber 5 as before, but the sub-injection port 10 actively injects fuel into the glow plug 8. Its orientation and position are set so that Further, the opening and opening operations of the main injection port 9 and the sub injection port 10 are performed individually by nozzle needles (not shown).

That is, the nozzle needles for the main injection port and the sub-injection port are always urged in the closing direction by springs, and the pressure of the fuel supplied under pressure through the fuel passages 11 and 12 is applied to the pressure receiving part. The main injection port 9 and the sub injection port 10 are opened by lifting the main injection port 9 in the opening direction, and the main injection port 9 is opened by a spring.
The opening pressure of
The valve opening pressure at 0 is set to about 12 (11/m1), which is lower than that at the main injection port 9.

Further, the fuel passage is branched into a main fuel passage 11 for the main injection port and an auxiliary fuel passage 12 for the auxiliary injection day in the valve body 7a of the fuel injection valve 7, and upstream from the branching point is a delivery pipe (not shown). It leads to the fuel injection pump via.

The auxiliary fuel passage 12 is provided with an on-off valve 13 that opens when the fuel is cold and closes when the fuel is warm. As shown in FIGS. 2 and 3, this on-off valve 13 enters and exits the auxiliary fuel passage 12 in a direction that crosses the auxiliary fuel passage 12.
2, and a spring 15 made of a shape memory alloy to move the valve body 14 in and out in response to the rise and fall of the engine temperature. And the valve body 14
is the valve body 7a of the fuel injection valve 7 adjacent to the auxiliary fuel passage 12.
It is slidably attached to a recess 16 formed in the auxiliary fuel passage 12, and when it is cold, the spring 15 exits and opens from the auxiliary fuel passage 12 due to the deformation action in the contraction direction of the spring 15, and when it is warm, the spring 1
Due to the deformation action in the direction of extension of fuel 5, it enters the auxiliary fuel passage 12 and closes it. Note that one end of the spring 15 is fixed to the bottom surface of the recess 16, and the other end is fixed to the bottom surface of the valve body 14.

The fuel injection system of this embodiment is constructed as described above, and therefore, when the engine is started (when cold), the spring 15 in the on-off valve 13 is activated as shown by the solid line in FIGS. 2 and 3. Due to the deformation in the contraction direction, the valve body 14 moves out of the auxiliary fuel passage 12, and the auxiliary fuel passage 12 is opened. Therefore, in this state, fuel supplied under pressure from the injection pump is injected into the sub-combustion chamber 5 from both the main fuel passage 11 and the sub-fuel passage 12. In this case, the injection from the auxiliary injection port 10 whose valve opening pressure is set to be low takes precedence, and the injection from the main injection port 9 immediately follows.

Since the fuel from the sub-injection port 10 is injected toward the glow plug 8, the fuel comes into active contact with the red-hot glow plug 8, and ignition and combustion are effectively performed.

During the wA period when the engine is warmed up, the valve body 14 plunges into the a1 fuel passage 12 due to the deformation of the spring 15 in the direction of extension, as shown by the imaginary lines in FIGS. 2 and 3. In order to close the fuel passage 12, fuel injection from the a1 injection port 10 is stopped. That is, during normal warm conditions, fuel is injected only from the main injection port 9.

In this embodiment, the on-off valve 13 for opening and closing the auxiliary fuel passage 12 is operated by a spring 15 made of a shape memory alloy, but it is not necessarily limited to the type shown in the drawings. For example, an electromagnetic on-off valve may be used. It is also possible to configure the opening/closing timing to be controlled based on a sensor that detects the engine oil temperature or water temperature.In other words, it is possible to control the opening/closing of the auxiliary fuel passage 12 in response to the temperature of the engine. It's good to have. Further, in this embodiment, the main injection port 9 and the sub injection port 10 are formed integrally with the fuel injection valve 7, but if there is no problem with the installation space for the cylinder head 2, they may be formed separately. No problem.

(Effects of the Invention) As detailed above, according to the present invention, in a pre-chamber type diesel engine, when the engine is cold started, the preheating device is injected from the sub-injection port installed separately from the main injection []. By making it possible to inject fuel towards the engine, it is possible to improve cold startability, which is a problem with the pre-chamber type.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional view showing a fuel injection device for a III-compartment diesel engine, FIG. 2 is a longitudinal sectional view showing an on-off valve for a DI fuel passage, and FIG. FIG. 3... Piston 5... Sub-combustion chamber 8... Glow plug 10... Sub-injection port 12... Sub-fuel passage 4°... Main combustion chamber 7... Fuel injection valve 9...・Main injection port 1...Main fuel passage 3...r! 1JrtJ patent applicant: θDA Automatic Loom Works Co., Ltd. Agent: Patent attorney: Fuhiko Okada (3 others) Figure 3

Claims (1)

[Claims] In a diesel engine equipped with a sub-combustion chamber, a main injection port and a sub-injection port for fuel are arranged side by side in the sub-combustion chamber, and the fuel injection direction of the sub-injection port is directed toward a preheating device installed in the sub-combustion chamber. A fuel injection device for a diesel engine, wherein a valve is installed in a fuel passage leading to the sub-injection port, which opens when cold and closes when warm.