JPH10325342A - Two cycle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a structure, suppress increasing of friction to the minimum so as to prevent reduction of an output, and prevent a cumulus of carbon and the like. SOLUTION: In a two cycle internal combustion engine of a mixture direct injection type, an operating piston 15 fitted to a pump operating chamber 10 formed on a combustion chamber side of a cylinder head 3 is moved in reciprocation according to change of pressure in the combustion chamber. Compressed air or mixture is supplied toward an upstream side of a mixture injection valve 31 for injecting mixture to combustion chambers 6, 7 by a pump P driven by the reciprocating motion of the operating piston 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection type two-stroke internal combustion engine, and more particularly to an intake system pump.

[0002]

2. Description of the Related Art A method using a pump mechanism to directly inject an air-fuel mixture into a combustion chamber has been known. For example, the method described in Japanese Patent Application Laid-Open No. 7-63141 discloses a method of rotating a crankshaft of an internal combustion engine. Is used as a power source, and an air-fuel mixture is injected into the combustion chamber by reciprocating an injection piston slidably fitted in a chamber communicating with the combustion chamber via a power transmission mechanism.

In addition, there has been proposed a method in which a part of the internal pressure in a cylinder is introduced into a pressure accumulating chamber to accumulate the pressure, and the fuel is injected in the next cycle.

[0004]

However, in the former example,
Since the rotation of the crankshaft is used, a belt transmission mechanism for transmitting power to the cylinder head side and a crank mechanism for converting the rotation transmitted from the belt into reciprocating motion of the injection piston are required, and the number of parts is large and the structure is complicated. And there is no freedom of layout. In addition, a decrease in output is inevitable due to an increase in mechanical friction.

In the latter case, there is a problem that the horsepower is reduced because the internal pressure in the cylinder is taken in and used, and that the residual gas is also taken in, so that carbon is deposited in the pressure accumulating chamber.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a two-cycle internal combustion engine having a simple structure, minimizing an increase in friction, preventing a decrease in output, and having no accumulation of carbon or the like. In providing an institution.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a two-stroke internal combustion engine of a direct fuel-air mixture type, which comprises a pump operating chamber formed on a combustion chamber side of a cylinder head. The fitted working piston reciprocates according to a change in pressure in the combustion chamber, and a pump driven by the reciprocating movement of the working piston causes compressed air or mixed air to flow upstream of a mixture injection valve that injects air-fuel mixture into the combustion chamber. A two-cycle internal combustion engine for supplying air was used.

The working piston for driving the pump is fitted into the pump working chamber formed on the combustion chamber side of the cylinder head and reciprocates according to the pressure change in the combustion chamber, so that the structure is simplified. Thus, the degree of freedom in layout is large, and increase in friction can be minimized to prevent a decrease in output. Since the pressure is not stored by taking in the cylinder pressure, there is no problem such as carbon deposition.

[0009] The second aspect of the present invention provides the second aspect of the present invention.
In the cycle internal combustion engine, the pump is configured such that a pump piston integrated with the working piston is reciprocally fitted into a pump chamber provided as an extension of the pump working chamber, and an intake reed valve and a discharge side are fitted to the pump chamber. A reed valve is provided.

Since the pump piston integrated with the working piston is reciprocally fitted into the pump chamber provided on the extension of the pump working chamber, and the suction side reed valve and the discharge side reed valve are provided in the pump chamber, the number of parts is reduced. And the structure is very simple, and there is almost no mechanical friction other than pump loss. A pump is provided locally on the cylinder head, and the degree of freedom of layout is large.

[0011] The invention according to claim 3 provides the invention according to claim 2.
In the cycle internal combustion engine, the working piston is urged by a spring and fits into the pump working chamber against the spring due to a rise in the pressure of the combustion chamber so that the end face of the working piston is flush with the surface of the combustion chamber. When the pressure in the combustion chamber drops, the spring projects into the combustion chamber due to the urging force of the spring.

When the piston that has risen in the cylinder reaches the top dead center, the working piston is fitted into the pump working chamber and the end face is made flush with the combustion chamber face. The total surface area S and volume V of the base engine and its combustion chamber are equal, and hence the ratio S /
Since the V ratio is also the same, a decrease in combustion efficiency can be prevented.

According to a fourth aspect of the present invention, there is provided the second aspect of the first aspect.
In the cycle internal combustion engine, the cylinder head has a main combustion chamber and an auxiliary combustion chamber, and the air-fuel mixture injection valve injects air-fuel mixture into the auxiliary combustion chamber. The air-fuel mixture is injected into the sub-combustion chamber to enable stable stratified combustion and prevent incomplete combustion.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described below with reference to FIGS. FIGS. 1 and 2 are schematic diagrams showing the internal structures of the cylinder 2 and the cylinder head 3 in the two-stroke internal combustion engine 1 according to the present embodiment.

A piston 4 reciprocates inside the cylinder 2, and a plurality of scavenging ports 5 are provided at predetermined positions of the cylinder 2. An auxiliary combustion chamber 7 is formed in the cylinder head 3 so as to be continuous with the main combustion chamber 6. The electrode of the ignition plug 8 faces the main combustion chamber 6, and the electrode of the ignition plug 9 faces the auxiliary combustion chamber 7. I have.

The cylinder head 3 is provided with an intake pump P. Main combustion chamber 6 of cylinder head 3
A pump working chamber 10 is formed with a large opening in the side inner surface, and a pump chamber 12 is formed through a small-diameter hole 11 as an extension of the pump working chamber 10, and a working piston 15 is slidably fitted in the pump working chamber 10. A pump piston 16 is slidably fitted in the pump chamber 12, and the working piston 15 and the pump piston 16 are combined with each other at the small-diameter hole 11 to be integrated and reciprocate together.

The working piston 15 has a large-diameter portion 15a on the distal end side and a small-diameter portion 15b on the proximal end connected to the pump piston 16, and the small-diameter portion 15b is cut into the large-diameter portion 15a so as to have an annular recess 15c. Is formed, a return piston 18 provided around the small diameter portion 15b is inserted into the annular concave portion 15c, the other end of the return piston 18 abuts the step of the small diameter hole 11, and the working piston 15 is integrated with the pump piston 16 in the main combustion chamber. It is biased to the 6 side.

The working piston 15 slides in the pump working chamber 10 with a piston ring 17 fitted on the peripheral surface of the large diameter part 15a, and the pump working chamber 10 covers the entire large diameter part 15a of the working piston 15. When the working piston 15 is pushed into the pump working chamber 10 against the return spring 18 and is fitted to the end, the end face 15d of the working piston 15 is connected to the main combustion chamber 6 as shown in FIG. It is the same plane as the inner surface.

On the other hand, the pump piston 16 has a large diameter portion on the tip side.
The piston ring 19 is fitted on the peripheral surface of the large diameter portion 16a and slides in the pump chamber 12. Working piston 15 is main combustion chamber 6
When the pump piston 16 protrudes from the pump piston 16 as shown in FIG.
The large-diameter portion 16a contacts the step of the small-diameter hole 15b, and the working piston 15 projects by a predetermined amount.

In the pump chamber 12, an intake side reed valve 21 is provided at an intake port 12a, and a discharge side reed valve 22 is provided at a discharge port 12b.
The discharge side reed valve 22 is a check valve, and alternately opens and closes with the reciprocation of the pump piston 16 to perform a pump function.

The intake port 12a is an outside air or an air cleaner.
38, the discharge port 12b is connected to the communication passage 25,
The communication passage 25 is connected to an upstream side of the air-fuel mixture ejection valve 31 of the air-fuel mixture supply device 30. As shown in FIG. 3, the air-fuel mixture supply device 30 is provided on the upstream side of the sub-combustion chamber 7 so that the air-fuel mixture injection valve 31 faces a space where the electrode of the ignition plug 9 faces.

The mixture injection valve 31 is driven and opened by the excitation of the electromagnetic coil 32. A fuel injection valve 35 is provided coaxially on the upstream side of the air-fuel mixture injection valve 31, and an air supply hole 34 communicates from the side with a mixing chamber 33 on the downstream side of the fuel injection valve 35. The communication passage 25 is connected to the supply hole 34.

The fuel injection valve 35 is also opened by being driven by the excitation of the electromagnetic coil 36, and is provided with a fuel supply hole 37 through which fuel is fed upstream. When the compressed air is supplied from the pump P to the mixing chamber 33 and the fuel injection valve 35 is opened at the same time as or slightly after the opening of the mixture injection valve 31, the fuel injected into the mixing chamber 33 mixes with the air. Then, the fuel is injected into the sub combustion chamber 7.

The air-fuel mixture injected into the sub-combustion chamber 7 forms a stratified structure in which the fuel concentration is gradually reduced in the sub-combustion chamber 7 from the upstream side to the downstream side. By igniting 9, stable stratified combustion can be caused, and unburned lubricating oil due to conventional incomplete combustion flows out to the exhaust system, and generation of white smoke caused by unburned lubricating oil, etc. Is suppressed.

Referring to the operation of the pump P for supplying compressed air to the mixing chamber 33, when the piston 4 descends and the internal pressure of the combustion chambers 6 and 7 decreases as shown in FIG. Thus, the pump piston 16 integral with the working piston 17 expands the pump chamber 12 to open the intake side reed valve 21 to take in air.

Then, the piston 4 rises and the combustion chambers 6, 7
When the internal pressure of the piston becomes high, as shown in FIG.
Is pressed and pushed against the return spring 18,
Therefore, the pump piston 16 reduces the size of the pump chamber 12 and opens the discharge side reed valve 22, so that the compressed air can be supplied to the mixing chamber 33 via the communication passage 25.

As described above, the pump P according to the present embodiment has the working piston 15 for driving the pump piston 16.
Are provided integrally with the cylinder head 3 so as to be reciprocally movable,
Since the driving source is the change in the internal pressure of the main combustion chamber 6, the number of parts is small, the structure is simple, the structure is compact, and the size is small.

Since the pump P is locally provided on the cylinder head 3 including its operating portion, the degree of freedom in layout is large. Except for the pump loss caused by the sliding of the pump piston 16 and the working piston 15 integrated therewith, there is no other mechanical friction, and extremely efficient pump work with little loss can be performed.

Since the pump P is provided in the cylinder head 3 at a position close to the air-fuel mixture injection valve 31 and the communication path 25 is short, the response speed is high and the response can be improved. In the pump P, since the pump chamber 12 sucks and discharges clean air from the outside air or the air cleaner, there is no such a problem that carbon is deposited as in a conventional pump which takes in a part of the cylinder internal pressure and accumulates the pressure.

When the piston 4 which has risen in the cylinder 2 reaches the top dead center, the working piston 15 for operating the pump P
Is inserted into the pump operation chamber 10 and the end face 15 d is inserted into the main combustion chamber 6.
Since the inner surface is flush with the inner surface, the total surface area S and volume V of the base engine and the combustion chamber of the basic structure without the pump working chamber are equal, and the ratio S / V ratio is also the same. The combustion efficiency is reduced due to the
It generated amount of C and NO _X are as or increase can be avoided.

The working piston 15 whose end face is largely exposed to the main combustion chamber 6 is heated, and the pump piston 16 integrally connected therewith becomes high temperature. The fuel is heated and discharged into the mixing chamber 33, so that atomization of the fuel is promoted.

In the above embodiment, the pump P supplies compressed air to the upstream side of the fuel-air mixture injection valve 31 and mixes it with the fuel injected from the fuel injection valve 35. The mixture thus supplied may be supplied to the upstream side of the mixture injection valve.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an internal structure of a cylinder and a cylinder head in a two-cycle internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a schematic diagram showing another state.

FIG. 3 is a sectional view of an air-fuel mixture supply device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 2 cycle internal combustion engine, 2 ... cylinder, 3 ... cylinder head, 4 ... piston, 5 ... scavenging port, 6 ... main combustion chamber, 7 ... sub combustion chamber, 8, 9 ... spark plug, 10 ... pump working chamber, 11… Small hole, 12… Pump chamber, 15… Working piston,
16 ... Pump piston, 17 ... Piston ring, 18 ... Return spring, 19 ... Piston ring, 21 ... Intake side reed valve, 22 ... Discharge side reed valve, 25 ... Communication path, 30 ... Air-fuel mixture supply device, 31 ... Air-fuel mixture Spout valve, 32 ... electromagnetic coil, 35
... Fuel injection valve, 36 ... Electromagnetic coil, 37 ... Fuel supply hole, 38 ...
Air cleaner, P… Pump.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/02 301 F02D 41/02 301B F02M 67/02 F02M 67/02 67/12 67/12

Claims (4)

[Claims] In a two-stroke internal combustion engine of a mixture direct injection type, a working piston fitted to a pump working chamber formed on a combustion chamber side of a cylinder head reciprocates according to a pressure change in the combustion chamber, A two-stroke internal combustion engine, wherein a pump driven by reciprocation of the working piston supplies compressed air or air-fuel mixture to an upstream side of an air-fuel mixture injection valve for injecting air-fuel mixture into a combustion chamber. 2. The pump according to claim 1, wherein a pump piston integrated with the working piston is reciprocally fitted into a pump chamber provided on an extension of the pump working chamber, and an intake reed valve and a discharge side are fitted to the pump chamber. The two-stroke internal combustion engine according to claim 1, further comprising a reed valve. 3. The working piston is urged by a spring and fits into the pump working chamber against the spring due to a rise in the pressure of the combustion chamber so that the end face of the working piston is flush with the surface of the combustion chamber. 3. The two-stroke internal combustion engine according to claim 2, wherein the spring protrudes into the combustion chamber by a biasing force of the spring when the pressure in the combustion chamber drops. 4. The two-stroke cycle according to claim 1, wherein the cylinder head has a main combustion chamber and a sub-combustion chamber, and the air-fuel mixture injection valve injects air-fuel mixture into the sub-combustion chamber. Internal combustion engine.