JPH0385327A - Insulated two-cycle gasoline engine - Google Patents

Abstract

PURPOSE:To increase intake quantity for increasing compression ratio and improve thermal efficiency of an engine by introducing intake air into an insulated combustion chamber in the vicinity of the top dead center of a piston after being raided in pressure with a compressor and cooled with an intercooler. CONSTITUTION:A compressor 1 is driven by a crankshaft 33 and intake air from an intake pipe 11 is raised in pressure while this high pressure intake air is made to pass through an air feeding pipe 13 equipped with an intercooler 14, to mix with fuel from a fuel injection nozzle 16, and supplied to an insulated cylinder 2. Meanwhile, together with arrangement of an insulated piston 21 inside the insulated cylinder 2, an insulated combustion chamber is formed between these. Moreover, an intake valve 27, an exhaust valve 28 and an exhaust duct 29 are respectively arranged on the upper part of the insulated cylinder 2. Namely, intake air is force fed into the insulated combustion chamber after being raised in pressure and cooled, immediately before combustion stroke of the engine, that is, in a timing corresponding to that form ending of the compression stroke to beginning of the expansion stroke in a conventional engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adiabatic two-stroke gasoline engine in which the inside of a combustion chamber is insulated from the outside.

(Conventional technology) Conventionally, in engines, of the heat energy generated by the combustion of fuel, about 20% of the heat energy is transferred to the engine body, is not used effectively, and is emitted to the outside by the cooling device, etc., and is wasted. . Therefore, the wall surface of the combustion chamber is covered with a heat insulating layer,
An adiabatic engine is proposed that blocks the transmission of thermal energy to the outside, increases the energy of exhaust gas by using the thermal energy that was conventionally transmitted to the outside, and effectively recovers the thermal energy using an exhaust turbine, etc. to improve the thermal efficiency of the engine. has been done.

It is also known that increasing the compression ratio of an engine improves the thermal efficiency of the engine.

(Issues to be Solved by the Invention 11) However, in such a conventional adiabatic engine, the wall surface of the combustion chamber is at a high temperature, so the intake air receives heat transfer from the wall surface and immediately expands, causing the following air to In addition, during the compression stroke, the intake air is compressed and simultaneously receives heat energy from the combustion chamber wall and expands, so the compression work is greater than that of a typical water-cooled engine. The compression end temperature is higher than that of the water-cooled engine, and the combustion gas temperature is also higher, increasing the difference between the combustion gas temperature and the inner wall surface temperature. However, thermal efficiency decreases because the thermal energy radiated to the outside through the heat insulating layer increases.Furthermore, when the temperature of the combustion gas becomes high, there is a problem that the inner wall of the combustion chamber deteriorates.

Furthermore, when gasoline is used as fuel for an adiabatic engine such as the one mentioned above, knocking occurs due to the high temperature at the compression end, making it impossible to operate the engine unless the compression ratio is extremely reduced, which leads to problems such as deterioration of thermal efficiency. Ru.

The present invention has been made in view of the above points, and provides an adiabatic two-stroke gasoline engine with excellent thermal efficiency by increasing the amount of intake air, increasing the compression ratio, and lowering the compression end temperature to suppress the occurrence of knocking. This is what we are trying to provide.

(Means for Solving the Problems) According to the present invention, the pressure of the adiabatic combustion chamber whose inner wall is covered with a heat insulating layer and the intake air introduced into the adiabatic combustion chamber is increased to near the compression end pressure in advance. It is possible to provide an adiabatic two-stroke gasoline engine characterized by having a compressor and an intake means for introducing intake air pressurized by the compressor into an adiabatic combustion chamber near top dead center.

(Function) In the adiabatic two-stroke gasoline engine of the present invention, a compressor provided separately from the adiabatic combustion chamber increases the pressure of air to near the compression end pressure, and the intake air is cooled by an intercooler. Since the pressurized intake air is forced into the adiabatic combustion chamber immediately before the combustion stroke, that is, from the end of the compression stroke of a conventional engine to the beginning of the expansion stroke, the intake efficiency does not decrease, and the intake air is removed from the combustion chamber wall. Since the amount of heat received by the cylinder is small, the compression end temperature does not become high, and since the air is compressed in a low temperature cylinder, the compression work does not increase. Since the temperature is low, even if gasoline is used as fuel, a high compression ratio can be achieved and thermal efficiency can be improved.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a mechanical diagram showing an adiabatic two-stroke gasoline engine according to the present invention.

In the figure, reference numeral 1 denotes a compressor, which is driven by a crankshaft 33, which will be described later, and increases the pressure of intake air from the intake pipe 11 to near the compression end pressure.

An air flow meter 12 is installed in the intake pipe 11 to detect the intake air flow rate in the intake pipe 11 and output a flow rate signal.

Air supply pipe 13 for supplying high-pressure intake air from the compressor 1
An intercooler 14 is disposed in the intercooler 14 to cool intake air whose temperature has increased due to compression by the compressor 1. The air pipe 13 also includes a throttle valve 15 that controls the air flow rate from the compressor 1 using No. 78 from the outside, and a throttle valve 15 that controls the amount of fuel injected into the air pipe 33 based on an external signal. A fuel injection nozzle 16 for producing a premixture with fuel is provided. The premixed gas is then sent to the heat insulating cylinder 2 via the air pipe 13.

A heat insulating piston 21 is disposed within the heat insulating cylinder 2 so as to be able to reciprocate. The head of the heat-insulating piston 21 is covered with a heat-insulating layer 22 made of ceramics or the like with low thermal conductivity, and the surface of the heat-insulating layer 22 is further covered and reinforced with a protective layer 23 made of a heat-resistant high-strength material. . Also,
The upper inner wall of the heat-insulating cylinder 2 is also covered with a heat-insulating layer 24 made of ceramics or the like having low thermal conductivity, and the surface of the heat-insulating layer 24 is covered with a protective layer 2 made of a heat-resistant high-strength material.
5. The lower inner wall is covered only with a protective layer 26 made of a heat-resistant, high-strength material.

The upper part of the heat insulating cylinder 2 communicates with the air pipe 13,
An intake valve 27 is provided at the communication port, that is, the intake port. Similarly, an exhaust valve 28 and an exhaust pipe line 29 are arranged at the upper part of the heat insulating cylinder 2. Note that the intake valve 27 and the exhaust valve 28 are connected to the camshaft 30.
It is driven to open and close by. A spark plug 31 is further disposed above the heat insulating cylinder 2 and ignites the premixed air in the combustion chamber formed by the heat insulating cylinder 2 and the head of the heat insulating piston 21 .

The heat insulating piston 21 is connected to a bin journal portion of a crankshaft 33 via a connecting rod 32, and the crankshaft 33 is connected via a belt 34.
It is connected to the compressor 1 and drives the compressor 1.

The air flow meter 12, throttle valve 15, and fuel injection nozzle 16 are connected to the control unit 4. The control unit 4 receives a flow rate signal from the air flow meter 12 and outputs a control signal to the throttle valve 15 and fuel injection nozzle 16.

The control unit 4 includes an air flow meter 12,
An input/output interface that controls input and output of signals to and from the throttle valve 15 and fuel injection nozzle 16, a ROM that stores programs and various related tables, a CPU that performs calculations based on the programs stored in the ROM, and a CPU that stores calculation results and data. RAM for temporary storage, control unit 4
It consists of a control memory etc. that controls the flow of internal signals.

Next, the operation of the adiabatic two-stroke gasoline engine of the present invention will be explained.

FIG. 2 is a diagram showing the relationship between the crank angle and the opening and closing states of the intake and exhaust valves.

In this figure, the vertical axis shows the opening degree of the intake and exhaust valves with respect to the crank angle θ.

When the air-fuel mixture in the combustion chamber is ignited by the spark plug 31 at a position near top dead center (TDC), the air-fuel mixture burns and expands, causing the piston 21 to descend. Then, just before the heat insulating piston 21 reaches the bottom dead center (BDC), the exhaust valve 28 is opened. Then, the combustion gas inside the combustion chamber is discharged from the exhaust pipe line 29 due to the internal pressure and the piston 21 rising through the bottom dead center (BDC).

Then, when the piston 21 rises to a predetermined position, the exhaust valve 28 is closed and the intake valve 27 is opened. Then, the high-pressure premixture in the air pipe 13 rapidly flows into the combustion chamber, and the intake valve 27 is closed at a position near the top dead center (TDC), and the spark plug 3 is closed.
1 and ignites the premixed mixture.

Note that the flow rate of the premixture flowing into the combustion chamber is determined by outputting a control signal from the control unit 4 to the throttle valve 15 based on the amount of depression of an accelerator pedal (not shown), thereby limiting the intake flow rate. Then, the control unit 4 calculates the fuel injection amount based on the intake air flow rate signal output from the air flow meter 12, and outputs a control signal to the fuel injection nozzle 16 so that a predetermined air-fuel ratio is achieved.

By the way, in a normal water-cooled gasoline engine, the compression ratio is set to 9 to 1o, which is the limit for knocking, and if the compression ratio is increased beyond that, the compression end temperature will rise and knocking will occur.

As explained above, the adiabatic two-stroke gasoline engine according to the present invention boosts the pressure of intake air in the compressor 1 which is separated from the combustion chamber, and generates a premixed mixture of intake air and fuel that is further cooled in the intercooler 14. , top dead center (TDC)
Since the air is forced into the combustion chamber at a position near the front and ignited immediately after being fed, knocking does not occur even if the intake pressure or compression ratio is increased compared to the conventional compression ratio. It is possible to expand at a high expansion ratio (compression ratio of general engines) without being limited by the compression ratio like a reciprocating gasoline engine, and it is possible to set the compression ratio of general engines to 20 or higher. Increasing the ratio improves thermal efficiency.

Furthermore, if the temperature of the premixture is low, the temperature of the combustion gas will be lower than in a so-called adiabatic engine, and the temperature difference with the combustion chamber wall will be small, so the amount of heat energy transferred from the combustion chamber wall will be reduced. Decrease.

Therefore, the combustion temperature does not become abnormally high, so the amount of heat transferred to the outside is small, and nitrogen oxides (NOx) are
The production of is also suppressed.

In the above explanation, the closing timing of the intake valve 27 was explained at a position near the top dead center (TDC).
TDC) Closing at a position near the rear does not depart from the spirit of the present application.

Although the present invention has been described in detail above, it is understood that various different embodiments can be easily made without departing from the spirit of the invention. The examples are not intended to be limiting.

(Effects of the Invention) As explained above, according to the present invention, the compressor provided separately from the adiabatic combustion chamber increases the pressure of air to near the compression end pressure, and the intake air is cooled by the intercooler,
Since the pressurized intake air is forced into the adiabatic combustion chamber immediately before and immediately after the combustion stroke of an adiabatic two-cycle gasoline engine, that is, at a timing corresponding to the end of the compression stroke of a conventional engine, the intake efficiency does not decrease, and the combustion Since the amount of heat received from the indoor wall to the intake air is small, the compression end temperature does not become high, and since the air is compressed in a low-temperature cylinder, there is no increase in compression work. ,
Since the compression end temperature is low, a high compression ratio can be achieved even when fuel C gasoline is used, and an adiabatic two-stroke gasoline engine that can improve thermal efficiency can be provided.

[Brief explanation of drawings]

FIG. 1 is a mechanical diagram showing an adiabatic two-stroke gasoline engine according to the present invention, and FIG. 2 is a diagram showing the relationship between the crank angle and the opening and closing states of intake and exhaust valves. 1...Compressor, 2...Insulated cylinder, 4...
・Control unit, 14... intercooler,
15... Throttle valve, 16... Fuel injection nozzle, 21... Heat insulating piston, 22, 24... Heat insulating layer, 31... Spark plug.

Claims (2)

[Claims] (1) An adiabatic combustion chamber whose inner wall is covered with a heat insulating layer, a compressor that increases the pressure of the intake air introduced into the adiabatic combustion chamber to near the compression end pressure, and a compressor that increases the pressure of the intake air that has been boosted by the compressor. 1. An adiabatic two-stroke gasoline engine, comprising an intake means for introducing air into an adiabatic combustion chamber near dead center. (2) The device according to claim (1), further comprising an intercooler provided between the compressor and the adiabatic combustion chamber and cooling the intake air pressurized by the compressor before being introduced into the adiabatic combustion chamber. Adiabatic 2-stroke gasoline engine.