JPH03105056A - Fuel feed device for two-cycle engine - Google Patents

Abstract

PURPOSE:To increase the engine output by the simple constitution by carrying out fuel injection from an assisting fuel injection valve, together with an air assisting fuel injection valve in the high speed operation, in the constitution in which the air assisting fuel injection valve for directly jetting fuel into a combustion chamber is provided. CONSTITUTION:Spark plugs 15a and 15b and air assisting fuel injection valves 16a and 16b are installed in the combustion chambers 14a and 14b for each cylinder of a two-cycle two-cylinder engine. Further, an assisting fuel injection valve 18 for directly jetting fuel into a crankcase C is installed into a suction passage 2, Though each fuel injection valve 16a, 16b, 18 is controlled by an electronic controller 13, almost all the parts of the demanded fuel quantity is supplied by the fuel injection from the fuel injection valves 16a and 16b in the low or intermediate speed revolution region of the engine, while the fuel injection quantity of the assisting fuel injection valve 18 is speedily increased so that the demanded fuel quantity is supplied, when the fuel injection quantity of each fuel injection valve 16a, 16b reaches a limit in the high speed revolution of the engine.

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Application Field The present invention is directed to a fuel supply device for a crankcase intake type two-stroke engine mounted on a motorcycle or the like, and particularly to a fuel supply device for injecting fuel directly into the combustion chamber of the engine. The present invention relates to a fuel supply device for a two-stroke engine equipped with an air-assisted fuel injection valve.

(2) Conventional technology Traditionally, two-stroke engines have had common drawbacks such as noise and vibration caused by irregular combustion and deterioration of fuel efficiency, deterioration of fuel efficiency due to air-fuel mixture blow-through during scavenging; In order to eliminate the disadvantages of increased oil consumption and the generation of white smoke, fuel is injected directly into the combustion chamber of the engine using an air-assisted fuel injection valve, and air scavenging is performed to enable stratified combustion within the combustion chamber. A new type of two-stroke engine has been proposed that eliminates this problem. (3) Problems to be Solved by the Invention However, in a two-stroke engine that performs in-cylinder injection using an air-assisted combustion injection valve, the crank angle range in which fuel can be injected is limited, so that the required fuel injection of the engine at high rotation speeds is limited. It was difficult to secure sufficient quantities, and this was an impediment to achieving high output. In addition, in the conventional two-stroke engine mentioned above, the pistons, the large and small ends of the connecting rods, the main bearings, etc. are lubricated only by direct injection of oil into the crankcase, so this is not suitable for high-speed, high-output engines. However, there was a problem in that the lubrication and cooling of the above-mentioned parts subject to a high heat load tend to be insufficient.

The present invention has been made in view of the above-mentioned circumstances, and in a two-stroke engine that injects fuel directly into the combustion chamber using an air-assist fuel injection valve, it secures the required fuel injection amount at high engine speeds, and also The aim is to enable higher output by improving the lubrication and cooling performance around the shaft.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a two-cycle crankcase intake system equipped with an air-assisted fuel injection valve that injects fuel directly into the combustion chamber. The engine fuel supply device is characterized in that an auxiliary fuel injection valve is provided in an intake passage leading to the crankcase, and fuel is supplied into the crankcase through the auxiliary fuel injection valve at least when the engine rotates at high speed.

(2) Function According to the above-mentioned structure, the fuel injected into the combustion chamber together with air from the air-assisted fuel injection valve mixes with the air scavenged into the combustion chamber from the crankcase, resulting in stratified combustion.
The main part of the engine's required fuel injection amount is covered by fuel injection from the air-assist fuel injection valve, but at least when the engine is running at high speed, fuel is injected from the auxiliary fuel injection valve into the intake passage to the crankcase. After the fuel lubricates and cools the crankcase, it is scavenged into the combustion chamber. This not only ensures the required fuel injection amount at high speeds, but also improves the lubrication and cooling performance around the crankshaft during high speeds, where the thermal load is large. (3) Examples Examples of the present invention will be described below based on the drawings. 1 and 2 show an embodiment of the present invention,
FIG. 1 is a diagram showing the overall structure of the present fuel supply system mounted on a motorcycle, and FIG. 2 is a graph showing the injection amount of each fuel injection valve with respect to the engine rotation speed.

FIG. 1 shows a fuel supply system according to the present invention installed in a two-wheeled motor vehicle.
This shows an example of application to a cycle engine. As is clear from the figure, this engine E is a two-stroke, two-cylinder engine with a crankcase intake system.
Two cylinders la and lb are arranged in a V-shape upward and forward from the crankcase C. An intake passage 2 connected to the crankcase C is provided with a throttle valve 3, a surge tank 4, and an oil injection nozzle 5, and a reed valve 6 is provided at the connection between the crankcase C and the intake passage 2. ing.

A crankshaft 7 supported in the center of a crankcase C has a piston 9a, which is slidably fitted into each cylinder la, lb via connecting rods 8a, 8b.
9b, and when the pistons 9a and 9b are near the bottom dead center, the crankcase C and cylinders la and Ib
There is a scavenging passage 1 in the crankcase C for transporting the upper part.
0a and 10b are shaped. Each cylinder la, lb
An exhaust bow is provided on the opposite side of the scavenging passages 10a and 10b. The exhaust bows 11a and 11b are swingably provided with exhaust timing control valves 12a and 12b for controlling the exhaust timing.

Pistons 9a. A combustion chamber 14a.9b shaped to oppose the top surface of the combustion chamber 14a. 14b
Inside the ignition plug 15a. The tips of L5b protrude, and the nozzles 17a . 1? b is open. On the other hand, a nozzle 19 of an auxiliary fuel injection valve 18 opens in the intake passage 2 to inject fuel directly into the crankcase C. and,
The air assist fuel injection valve L6a. 16b and the auxiliary fuel injection valve 18 are supplied with fuel from a fuel tank 20 via an electromagnetic feed bomb 21 and a pressure regulator 22. A pump shaft 25 supported by the crankcase C and connected to the crankshaft 7 via gears 23, 24 includes a water pump 2G for circulating cooling water and the air assist fuel injection valves 16a. An air pump 27 for supplying air to 16b is coaxially arranged. A sub air cleaner 28 separate from the main air cleaner (not shown) connected to the intake passage 2 is connected to the upstream side of the air pump 27, and the downstream side thereof is connected to the air pump 27 via a pressure regulator 29 and a surge tank 30. It is connected to each air assist fuel injection valve 16a, 16b.

The electronic control unit 31 consisting of a microcomputer includes
The throttle opening THg detected by the throttle opening sensor 33 provided on the throttle grip 32, the engine rotation speed Ne detected by the engine rotation speed detector 34 provided in the crankcase C, and the engine rotation speed Ne detected by the cooling water temperature detector 35. The coolant temperature TW, the atmospheric temperature Ta detected by the atmospheric temperature detector 36, the intake manifold pressure Pb detected by the manifold pressure detector 37, and the atmospheric pressure Pa detected by the atmospheric pressure detector 38 are input. . The electronic control device 3l processes each of the above signals, controls the electromagnetic feed bomb 21 via the relay 39, controls the throttle valve 3 via the actuator 40, and further controls the actuator 4.
The exhaust timing control valves 12a, 12 via 1a, 4lb
Control b. and the actuator 40.41
The positions of a and 4lb are respectively controlled by potentiometers 42.
It is fed back to the electronic control unit 31 via 43a and 43b. Further, the electronic control device 31 controls the fuel injection amount control terminals 44a.
44b and air injection amount control terminals 45a and 45b, and is also connected to a fuel injection amount control terminal 46 of the auxiliary fuel injection valve 18.

Next, the operation of the embodiment of the present invention having the above-mentioned structure will be explained. The electronic control device 31 receives the throttle opening THg from the throttle opening sensor 33, which changes depending on the rider's operation.
, the engine rotation speed Ne from the engine rotation speed detector 34, which changes depending on the operating state of the engine E, the cooling water temperature Tw from the cooling water temperature detector 35, the intake eyebrow pressure Pb from the manifold pressure detector 37, and the atmosphere. The atmospheric temperature Ta from the atmospheric temperature detector 36 changes depending on the state of
Atmospheric pressure detector Atmospheric pressure Pa from 3rd day is input.

The electronic control device 31 processes each of the above signals and controls the fuel injection amount of the air assist fuel injection valves 16a, 16b and the auxiliary fuel injection valve 18. As shown in FIG. 2, the required fuel amount of the engine E mainly depends on the engine speed Ne, and in the low speed rotation range and medium speed rotation range, most of the required fuel amount is from the air assist fuel injection valves 16a and 16b. It is powered by fuel injection. The amount of fuel injected from the air-assisted fuel injection valves 16a, 16b rapidly increases as the engine speed Ne increases. When the engine E is in a high speed rotation state, the air assist fuel injection valves 16a, 16
When the fuel injection amount b almost reaches its limit, the fuel injection amount of the auxiliary fuel injection valve 18 increases rapidly in order to satisfy the fuel amount required by the engine E. Control of the fuel injection amount of the air assist fuel injection valves 16a, 16b and the auxiliary fuel injection valve 18 is performed as follows. That is, when the electromagnetic feed pump 21 is driven by a control signal from the electronic control device 31, the fuel in the fuel tank 20 is supplied to the air assist fuel injection valves 16a, 16b and the auxiliary fuel injection valve 18 through the pressure regulator 22. It will be done. On the other hand, an air pump 27 driven by a bomb shaft 25 linked to the crankshaft 7 allows air to pass through a sub air cleaner 28 and be purified through a pressure regulator 29 and a surge tank 30 to the air assist fuel injection valves 16a and 16b. Supplied.
The fuel and air that have reached the air assist fuel injection valves 16a, 16b are then transferred to the fuel injection amount control terminals 44a, 44b and the air injection amount control terminal 45a. The injection amount is duty-controlled by a control signal input to the air assist fuel injection valves 16a, 16b, and the fuel mixed with air is atomized and directly injected into the combustion chambers 14a, 14b. The fuel supplied to the auxiliary fuel injection valve 18 is injected into the intake passage 2 with the injection quantity being duty-controlled by a control signal input to the fuel injection quantity control terminal a++, and is injected into the intake passage 2, thereby injecting the fuel into the crankcase C and the scavenging passages 10a and 10b. The fuel is supplied to the combustion chambers 14a and 14b through the combustion chambers 14a and 14b. At this time,
The fuel injected from the auxiliary fuel injection valve 18 works together with the oil injected from the oil injection nozzle 5 provided in the intake passage to lubricate and cool the area around the axis of the crankshaft 7 inside the crankcase C.

At the same time, mainly as the engine speed Ne increases, the actuators 41a and 4lb are controlled to advance the exhaust timing of the exhaust timing control valves 12a and 12b, and as the throttle opening THg increases, the opening of the throttle valve 3 increases. Actuator 40 is controlled to increase. As a result, in conjunction with the control of the fuel injection amount of the air-assisted fuel injection valves 16a, 16b and the auxiliary fuel injection valve 18 described above, the air-fuel ratio of the air-fuel mixture in the combustion chamber is maintained at an optimum state, and the engine E is heated. Efficient driving is performed. Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the embodiments described above, and various small design changes may be made without departing from the scope of the invention described in the claims. It is possible to do so.

For example, the sub air cleaner 28 that purifies the air supplied to the air pump 27 can be shared with the main air cleaner. Furthermore, the air bomb 27 does not necessarily need to be disposed coaxially with the water pump 26.

C. Effects of the Invention As described above, according to the present invention, fuel is injected from the auxiliary fuel injection valve in addition to the fuel injection from the air-assist fuel injection valve when the engine rotates at high speed, resulting in high-performance air-assist fuel injection. The required fuel injection amount for the engine can be secured without using a valve, and as a result, the output of the engine can be improved.

In addition, especially during high-speed rotation with a large heat load, the fuel injected from the auxiliary fuel injection valve into the intake passage to the crankcase lubricates and cools the crankcase and then scavenges into the combustion chamber, resulting in air assist. By adopting a fuel injection valve, it is possible to improve the lubrication and cooling performance around the crankshaft, which has deteriorated.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
FIG. 1 is an overall configuration diagram of the present combustion supply system installed in a motorcycle, and FIG. 2 is a graph showing the injection amount of each fuel injection valve with respect to the engine rotation speed. 2...Intake passage, 14a, 14b...Combustion chamber, 16
a. 16b...Air assist fuel injection valve, 18...
auxiliary fuel injection valve

Claims (1)

[Claims] In a fuel supply system for a crankcase intake type two-stroke engine equipped with an air-assisted fuel injection valve (16a, 16b) that injects fuel directly into the combustion chamber (14a, 14b), an intake passage leading to the crankcase (C). (2
) is provided with an auxiliary fuel injection valve (18), and fuel is supplied into the crankcase (C) through the auxiliary fuel injection valve (18) at least when the engine (E) rotates at high speed. Engine fuel supply system.