JPS63192912A - Direct injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To make high pressure fuel injection system unnecessary by introducing pressure in a combustion chamber at the time of compression stroke into an auxiliary cylinder through a check valve, and by introducing it to a mixture chamber with fuel after the pressure is raised by action of an auxiliary piston so as to inject fuel having made into minute particle in the combustion chamber. CONSTITUTION:When a piston 2 is lifted and pressure in a combustion chamber 21 is raised in a compression stroke, high pressure in the combustion chamber 21 flows into a high pressure air chamber 41 of an auxiliary cylinder 4 through a check valve 43. The air in the high pressure air chamber 41 is moreover raised accompanied with closure of the check valve 43 when an auxiliary piston 5 is lowered by a cam device 6 at the point a little before the piston 2 reaches the compression top dead center. And when the piston 2 reaches in the neighborhood of the top dead center, if an opening/closing valve 11 is raised by an electromagnetic solenoid 12, a fuel injection hole 101 is opened and compressed air in the combustion chamber 21 flows in the mixture chamber 10. Next, an air introducing hole 9 and a fuel introducing hole 13 are opened simultaneously and high pressure air and fuel are mixed with each other, and it is injected from the fuel injection hole 101.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an internal combustion engine, and particularly to a direct injection internal combustion engine of the type in which fuel is injected directly into a combustion chamber.

[Conventional technology]

In a direct injection engine, it is necessary to efficiently generate an air-fuel mixture in a short period of time, and the efficiency of air-fuel mixture generation has a large effect on the combustibility of the engine. As a method to improve combustion in direct injection diesel engines, an auxiliary piston separate from the piston with a combustion chamber is inserted into an auxiliary cylinder formed in the cylinder head, and the air compressed by this auxiliary piston is used at the end of fuel injection. A method has already been proposed in which air is forced into the combustion chamber to generate air flow and promote mixing (
JP 59-110829).

[Problem that the invention seeks to solve]

However, this compressed air is generated only by the auxiliary piston, and high-pressure injection cannot be expected because the speed of the auxiliary piston is limited. Therefore, this compressed air alone cannot sufficiently promote the mixing between the air in the combustion chamber and the fuel spray injected from the fuel injection nozzle, resulting in a problem that the fuel cannot be improved.

[Means for solving problems]

In order to solve such problems, according to the present invention,
An auxiliary piston is installed in the auxiliary cylinder so that it can slide back and forth,
The high-pressure air chamber of the auxiliary cylinder is connected to the combustion chamber through a first communication passage having a check valve that allows air to flow only to the high-pressure air chamber side, and the mixture is connected to the combustion chamber through a fuel injection hole. A chamber is provided, the mixing chamber is connected to the high pressure air chamber through a second communication passage, and is connected to a fuel pressure feeding means through a fuel passage, and the opening and closing of the fuel passage and the second communication passage are controlled by an on-off valve. A direct injection internal combustion engine is provided.

[For production]

During the compression stroke, the compressed air in the combustion chamber flows into the high-pressure air chamber of the auxiliary cylinder through the first communication passage, and at the end of the compression stroke, the auxiliary piston descends to compress the high-pressure air chamber, increasing the pressure to a level higher than the highest pressure in the combustion chamber. generate. When the on-off valve opens, the fuel from the fuel passage and the high pressure air from the second communication passage are mixed in the mixing chamber, and atomized fuel spray is injected into the combustion chamber.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, a combustion chamber 21 is formed by a cylinder head 1, a piston 2, and a cylinder 3 of a diesel engine. Note that, in FIG. 1, illustrations of an intake port and an intake valve for sucking fresh air into the combustion chamber 21, and an exhaust boat and an exhaust valve for discharging combustion gas are omitted.

In the present invention, an auxiliary cylinder 4 is provided inside the cylinder head 1.
is formed, and an auxiliary piston 5 is inserted into this auxiliary cylinder 4 so as to be able to reciprocate.

The upper side of the auxiliary piston 5 is connected to the piston rod 7,
This piston rod 7 is urged upward by a spring 8 so that its upper end always comes into contact with the cam device 6. The auxiliary cylinder 4 below the auxiliary piston 5 is defined as a high pressure air chamber 41, and this high pressure air chamber 41 is connected to the communication hole 4.
2 to the combustion chamber 21. The communication hole 42 is provided with a check valve that allows air to flow only from the combustion chamber 21 side to the high pressure air chamber 41 side, that is, a check ball 43 and a spring 44 that biases the check ball 43.

Further, a cylindrical mixing chamber IO is formed in the cylinder head 1 adjacent to the combustion chamber 21 . This mixing chamber 10 is connected to a combustion chamber 21 through a fuel injection hole 101, and is connected to a high-pressure air chamber 41 of the auxiliary cylinder 4 through an air introduction hole 9, and through a fuel introduction hole 13 and a fuel pipe 14. and is connected to the fuel pump 15. Note that the fuel introduction hole 13 is provided with a check valve 131 that prevents backflow of fuel toward the fuel pump 15 side. Inside the mixing chamber 10,
A plunger-shaped on-off valve 11 that opens and closes the fuel injection hole 101, the air introduction hole 9, and the fuel introduction hole 13 is inserted. The on-off valve 11 is driven to open and close by an electromagnetic solenoid 12, and is urged by a spring 111 in a direction to close the fuel injection hole 101 (and the air introduction hole 9 and the fuel introduction hole 13).

Next, the operation of the present invention will be described. When the relevant cylinder of the engine enters the compression stroke and the piston rises, 1. The pressure within the combustion chamber 21 increases. For example, if the compression ratio of this diesel engine is 18, the pressure within this combustion chamber 21 will be around 45 kg/ca1 at maximum. This high pressure air flows into the communication hole 42, pushes up the check ball 43 against the spring 44 to open it, and flows into the high pressure air chamber 41 of the auxiliary cylinder 4. The pressure inside the combustion chamber 21 just before the piston 2 reaches compression top dead center is, for example, 30 kg/co!
At the point when the front and back are reached, the drive device (in the embodiment shown in FIG. 1,
The auxiliary piston 5 is moved downward by the overhead cam device ff6). For this reason, the pressure inside the high pressure air chamber 4 of the auxiliary cylinder 4 rises rapidly, and the check ball 43 is moved by the spring 44.
, and the communication between the high pressure air chamber 41 of the auxiliary cylinder 4 and the combustion chamber 21 is cut off. A piston ring 51 is attached to the auxiliary piston 5, while an air introduction hole 9
is closed by the on-off valve 11, so the high pressure air chamber 41 and the air introduction hole 9 of the auxiliary cylinder 4 are maintained at high pressure.

For example, if the compression ratio of the auxiliary cylinder 4 is 3, this pressure will be about 130 kg/cfi.

On the other hand, the fuel pump 15 is driven by the engine itself or a motor (not shown) powered by a panteri power source, and maintains a constant pressure at all times in the fuel introduction hole 13 through the fuel pipe 14.
For example, the fuel is filled at 100 kg/cd. The pressure of this fuel is required to be several 100 kg/ffl in the fuel injection system of a normal direct injection diesel engine, but in the case of the present invention, the pressure of the fuel is equal to the air pressure in the auxiliary cylinder high pressure air chamber 41. It's okay to use a pressure that doesn't make much of a difference.

In such a state, when the piston reaches near the top dead center, the on-off valve 11 is raised by the electromagnetic solenoid 12 which is a driving device. As the on-off valve 11 rises, the fuel injection hole 101 first opens, and the compressed air in the combustion chamber 21 flows into the mixing chamber 10. Immediately after that, the air introduction hole 9 and the fuel introduction hole 13 open almost simultaneously, and high-pressure air and fuel flow into the mixing chamber 10 with even stronger pressure, filling the mixing chamber 10.

Since this pressure is considerably higher than the maximum compression pressure in the combustion chamber 21, the high-pressure air and fuel mix with each other, atomize the fuel, and inject it into the combustion chamber 21 through the fuel injection hole 101.

In this case, the fuel injection rate can be changed by changing the mutual shapes of the fuel injection hole 101 and the on-off valve 11. For example, the optimal fuel injection rate can be set by changing the angle of the tapered end of the on-off valve 11 facing the fuel injection hole 101, or by providing an appropriate throttle on the fuel injection hole 101. can.

Further, the fuel injection amount is determined by the opening time of the on-off valve 11 controlled by the electromagnetic solenoid 12, although it depends on the relationship with the above-mentioned fuel injection rate. That is, the fuel injection amount is obtained by controlling the electromagnetic solenoid 12 so as to be an appropriate fuel amount according to the inflow amount of fresh air measured by an air flow meter (not shown).

Since the fuel injected into the combustion chamber 21 has already been atomized and well mixed by the high-pressure air, there is almost no ignition delay, and combustion can be reliably controlled by the fuel injection rate described above. become. Therefore, poor mixing will not occur due to lack of air, and combustion will occur with extremely low smoke concentration. Note that, since the pressure of the fuel flowing into the mixing chamber 10 is not higher than the pressure of the air flowing in from the air introduction hole 9, the fuel does not flow into the auxiliary cylinder 4 side. Moreover, in order to prevent this, an appropriate check valve may be provided in the air introduction hole 9.

FIG. 2 shows that when the on-off valve 11 is raised, the high-pressure air a that has flowed into the mixing chamber 10 through the air introduction hole 9 and the fuel f that has flowed through the fuel introduction hole 13 collide and mix in the mixing chamber IO. death,
The fuel is atomized through the fuel injection hole 101, and the spray S mixed with air is ejected into the combustion chamber 21.

〔Effect of the invention〕

According to the present invention, there is no need for a high-pressure fuel injection system (injection pump, high-pressure pipe, injection nozzle), which is essential in conventional direct-injection diesel engines, so costs can be significantly reduced. Furthermore, by eliminating the need for a high-pressure fuel injection system, it is possible to easily increase speed, increase output, and improve the driving feeling.

Furthermore, conventionally, the air flow inside the combustion chamber depended on the intake swirl flow, but in the present invention, the air flow is generated by injecting compressed air into the combustion chamber, so a complex process is required to generate the swirl flow. This eliminates the need for a shaped intake boat, and it is possible to make the intake boat more linear and have a smaller inflow resistance. As a result, it is possible to create an intake system with higher intake efficiency than before, and an improvement in engine performance can be expected.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the periphery of the combustion chamber of a direct injection internal combustion engine according to the present invention, and FIG. 2 is a diagram illustrating the function of the mixing chamber. 1... Cylinder head, 2... Piston, 2
1... Combustion chamber, 3... Cylinder, 4...
...Auxiliary cylinder, 41...High pressure air chamber, 5...
・Auxiliary piston, 6...Cam device, 42...
・Communication hole (first communication path), 43...Check ball (check valve), 9...Air introduction hole (second communication path), 10...Mixing chamber, 101...Fuel injection hole , 11... Opening/closing valve, 12... Electromagnetic solenoid, 13... Fuel introduction hole, 15... Fuel pump.

Claims (1)

[Claims] 1. An auxiliary piston is provided in an auxiliary cylinder so as to be able to reciprocate and slide, and the high pressure air chamber of the auxiliary cylinder is connected to the combustion chamber through a first communication passage having a check valve that allows air to flow only to the high pressure air chamber side. On the other hand, a mixing chamber communicating with the combustion chamber through a fuel injection hole is provided, and the mixing chamber is connected to the high-pressure air chamber through a second communication passage, and is connected to a fuel pressure feeding means through a fuel passage. A direct injection internal combustion engine in which opening and closing of a fuel passage and the second communication passage are controlled by an on-off valve.