JPS5937267A - Quick evaporation device for liquid fuel - Google Patents

Abstract

PURPOSE:To improve an ignition property and obtain a cold starting property which is not inferior to a gasoline engine by a method wherein the diameter of the grain of the mist of alcohol fuel is atomized and mixture, having a necessary mixing ratio, is formed. CONSTITUTION:From the cold starting of the engine 10 to the warming of the engine, the flow amount of bypass air is controlled to a necessary amount by an air control valve 15 and the bypass air is maintained in a high-temperature condition by heating it to a predetermined temperature by a pre-heating device 2 and contacting it with a hot surface 4a in a pre-mixing chamber 3. On the other hand, the methanol fuel is injected into the pre-mixing chamber 3 from the injection port 7a of the low-pressure injection device 7. At this time, the injection amount of the methanol fuel is controlled into a necessary amount by a control unit 16, the fuel is blown against the hot surface 4a of a hot surface evaporating device 4, is evaporated, atomized and mixed with said bypass air, thereby forming the mixture of the predetermined mixing ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention forms a mixture with good ignitability from liquid fuel and supplies it to an internal combustion engine, making it possible to perform from cold start to steady operation of the internal combustion engine with a single fuel system. The present invention relates to a rapid evaporation device for liquid fuel for an internal combustion engine, and in particular to a rapid evaporation device for alcohol fuel.

Carburetor when operating a spark-ignition power combustion engine with alcohol fuel instead of conventional gasoline fuel.

A fuel supply system that uses a fuel injection system or the like cannot form an ignitable air-fuel mixture when it is cold, making it difficult to start the system. For this reason, gasoline fuel is used only at the time of starting, and the engine is switched to alcohol fuel after it has been warmed up. Therefore, two systems are required for the fuel and fuel supply system, compared to when operating on gasoline fuel. This is extremely disadvantageous.

The purpose of the present invention is to improve ignition performance by atomizing the spray particle size of alcohol fuel and forming a mixture having a required mixture ratio, thereby obtaining cold startability comparable to that of a gasoline engine. .

First, the basic principle of the present invention will be explained. It is known that the amount of heat dQ and time T required for evaporation of normal fuel are expressed by the following formula: dQ=c1.L.4zr2d r T=02.a2.L. However, C1 and C2 are constants determined by physical properties of fuel 9 ambient temperature, etc.
L is the latent heat of vaporization, r is the droplet radius, and a is the initial droplet diameter before evaporation.

Therefore, since the amount of heat dQ is controlled by the surface area 4πr2 of the droplet, the smaller the droplet to be heated, the more the smaller the droplet is.

It can be heated efficiently. Further, since the time T is also controlled by the initial droplet diameter a, the smaller the heated droplet, the faster it can evaporate.

Furthermore, it is known that the latent heat of vaporization decreases as the pressure of the fuel increases, so by forming fuel into small droplets and heating them in a high-pressure, high-temperature environment, it is possible to evaporate the fuel in a short time and with a small amount of heat. , it becomes possible to atomize the particles.

By the way, when implementing a rapid evaporation device for liquid fuel based on the above-mentioned principle, the problem is how to form fuel particles with a small particle size and how to form a homogeneous air-fuel mixture when the fuel is cold.

However, in order to form the above-mentioned high-temperature, high-pressure environment and a homogeneous air-fuel mixture with good ignitability using a single method, the system must become complicated and costly.

The present invention enables cold starting even in extremely cold regions where the engine temperature drops below 120°C, and also organically combines a preheating device, a low pressure injection device, and a hot surface evaporation device. The present invention provides a liquid fuel rapid evaporation device that is simplified.

That is, according to the present invention, fuel controlled to a required injection amount is injected and evaporated by a low-pressure injection device onto the high-temperature hot surface portion of a hot surface evaporator provided in a premixing chamber, and air is evaporated. Air metered by a regulating valve and heated by a preheating device is supplied into the premixing chamber, the fuel particles and air are mixed at a required mixture ratio, and the mixture is sucked into the engine. The fuel particles are rapidly evaporated in a high-pressure, high-temperature environment during the compression stroke, making it easy to start cold.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

The drawing shows the configuration of a rapid evaporator according to the present invention, in which the rapid evaporator 1 includes an intake air preheating device 2, an engine 10
3. A premixing chamber that passes through the A hot surface evaporator 4 having a hot surface portion 4a disposed approximately in the upper center of the premixing chamber 3 in the figure. A low-pressure injection device 7 for injecting the required amount of methanol fuel into the premixing chamber 3 from the fuel tank 6 via the fuel pump 5. and a reformed gas injection device 9 that injects the reformed gas obtained from the reformed gas generator 8 into the premixing chamber 3 during steady operation.

An air cleaner 11 is installed on the earthen wall of the premixing chamber 3. An intake pipe 13 is connected through the throttle valve 12, and a bypass 14 branched from the intake pipe 13 on the upstream side of the throttle valve 12 is connected to the upper side wall of the premixing chamber 3.
4, an air regulating valve 15° and a preheating device 2 are interposed in sequence. The air regulating valve 15 controls the passage area of the air taken in from the intake pipe 13 via the bypass 14 by a thermostat (not shown) that is activated depending on the temperature of the cooling water of the engine 10, and adjusts the amount of the air. The heating device 2 heats the air metered by the air regulating valve 15 to a required temperature using, for example, a conventionally known PTC honeycomb heater.

The hot surface evaporator 41 located approximately at the upper center of the premixing chamber 3 is electrically connected to a flat hot surface portion 4a formed by covering a ceramic heater with a high temperature rise rate with a thin body plate having high thermal conductivity. By heating, the surface temperature of the hot surface portion 4a is maintained at a predetermined high temperature.

A low-pressure injection device 7 and a methanol fuel injection lower a are arranged on the upper side wall of the premixing chamber 3 so as to face the hot surface section 4a4, and the control unit 16 adjusts the injection amount of methanol fuel. . That is, 16 control units, 1 water temperature sensor 16a, 2 rotation speed sensors 16
b. Engine 1 detected by boost pressure sensor 16c.
0 cooling water temperature.

The injection amount is adjusted by calculating and controlling the opening period of the low-pressure injection valve 7b based on the rotational speed of the engine 10 and the boost pressure in the premixing chamber 3. The low-pressure injection device 7 is, for example, a type of jetronic valve, for example, with an injection pressure of 2
．． 5kg/cm2. Injection amount 380 cc/min,
A material used for single point 1 injection with an average particle size SMD of 80 pm is used.

A reformed gas injection device 9 is disposed on the lower side of the premixing chamber 3, that is, on the engine IO side, with a reformed gas injection port 9a facing into the premixing chamber 3, and the engine 10 is warmed up and operated normally. When this occurs, the control unit 16 acts as in the case of the low-pressure injection device to open the reformed gas injection valve 9b and inject the required amount of reformed gas into the premixing chamber 3.

The premixing chamber 3 is configured to supply a mixture of methanol and air formed within the premixing chamber 3 to the engine 10, as will be described later.

In the above configuration, from cold start to warm-up of the engine 10, the slot valve 12 is closed and the air taken in from the intake pipe 13 is passed through the air cleaner 11° bypass 14 to the opening 14a of the bypass 14 to the premixing chamber. Let it flow into 3. At this time, the bypass air is regulated to a required flow rate by the air regulating valve 15 as described above, heated to a predetermined temperature (for example, 200° C.) by the preheating device 2, and then heated to the premixing chamber 3.
contact with the inner hot surface part 4a, and the predetermined temperature (e.g. 200°C)
The high-temperature state is maintained by the hot surface portion 4a that is heated.

On the other hand, methanol fuel is supplied to the fuel pump 5 from the fuel tank 6.
The fuel is injected into the premixing chamber 3 from the injection lower a of the low-pressure injection device 7 via. At this time, as described above, the methanol fuel is controlled by the control unit 16 at a required injection rate and is blown against the hot surface section 4a of the hot surface evaporator 4, and is evaporated from the surface of the hot surface section 4a having the predetermined temperature to form fine particles. The air is mixed with the bypass air to form a mixture having a predetermined mixing ratio.

The mixture of the methanol particles and the air, which has been formed at high pressure and at a required mixing ratio as described above, is supplied to the engine 10 from the premixing chamber 3, and the methanol fuel particles are further heated to a high temperature by the adiabatic compression stroke of the engine 10. When the pressure is increased, it evaporates rapidly and becomes even more atomized.

When the engine is under high load or full load, when methanol is gasified, the volume increases and the engine intake air volume decreases (for example, the filling efficiency drops to about 50%), so raw methanol is supplied again and the above-mentioned By internally cooling the engine using latent heat of vaporization, it is possible to increase the amount of intake air in the engine and improve output performance.

Next, when the engine 10 warms up and reaches steady operation, the low pressure injection valve 7b is activated by the action of the control unit 16 as described above.
is closed, and the reformed gas injection valve 9b is opened, and the reformed gas obtained by the reformed gas generator 8 is injected into the premixing chamber 3 from the reformed gas injection port 9a. At this time, the throttle valve 12 is opened to allow the air taken in from the intake Iv13 to directly flow into the premixing chamber 3, thereby forming a mixture of the reformed gas and the air. In this manner, the thermal efficiency of the engine 10 can be increased by supplying the mixture of reformed gas and air to the engine 1o during steady operation.

Although the present embodiment has been described using methanol as the fuel, the present invention is not limited to this, and gasoline may also be used as the fuel.

As explained above, according to the present invention, fuel controlled to a required injection amount by a low-pressure injection device is injected and evaporated onto the high-temperature hot surface portion of the hot surface evaporator provided in the premixing chamber. , the amount of air adjusted by the air regulating valve and heated by the preheating device is supplied into the premixing chamber, the fuel particles and air are mixed at a required mixing ratio, the mixture is sucked into the engine, and the air is heated by the preheating device. By rapidly evaporating the fuel particles in a high-pressure, high-temperature environment during the engine's compression stroke, the engine can be easily cold-started even in extremely cold regions. Further, by integrating the three systems of the air preheating device, the fuel hot surface evaporation device, and the fuel low-pressure injection device, the configuration of the device is simplified and manufacturing costs are reduced.

In addition, if liquid methanol fuel is used at full load, the engine intake volume can be increased to compensate for the decrease in engine intake volume due to the increase in volume of vaporized methanol, and engine performance can be improved (approximately 110%). During steady operation after warming up the engine, the thermal efficiency of the engine can be increased (approximately 50%) by using reformed methanol fuel gas.

Furthermore, if gasoline fuel is used, the engine can be operated at a proper mixture ratio from the start of the engine until it is warmed up, resulting in a significant improvement in emissions and fuel efficiency.

[Brief explanation of the drawing]

The drawing is a diagram showing the configuration of an embodiment of a rapid evaporation device for liquid fuel according to the present invention. 1... Rapid evaporator, 2... Preheating device, 3...
Premixing chamber, 4... Hot surface evaporator, 4a... Hot surface section,
7...Low pressure injection device, lO...engine, 15...
・Air adjustment valve. Applicant: Diesel Kiki Co., Ltd. Agent: Patent Attorney: Toshihiko Watanabe

Claims (1)

[Claims] 1. A low-pressure injection device injects and evaporates fuel, which is controlled to the required injection amount, onto the high-temperature hot surface of the hot surface evaporator installed in the premixing chamber. Air heated by a heating device is supplied into the premixing chamber, the fuel particles and air are mixed at a required mixture ratio, the mixture is sucked into the engine, and the mixture is heated in a high pressure and high temperature environment due to the compression stroke of the engine. A rapid evaporation device for liquid fuel characterized by rapidly evaporating fuel particles.