JPS6158662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine equipped with a fuel reformer.

Current automobile gasoline engines use fuel lean combustion and large amounts of exhaust recirculation to suppress _NO As a countermeasure, it is considered that one effective means is to reform current hydrocarbon fuels to generate hydrogen and burn a mixture of hydrogen, carbon monoxide, and hydrocarbons in a diluted state.

Various studies have already been conducted on reforming such fuels, but in general, the heat generated in the reformer cannot be used effectively, resulting in loss, and it is difficult to reform using a catalyst. However, there are problems in that it is relatively expensive.

The present invention uses, as such a fuel reformer, an auxiliary engine that is operated by supplying hydrocarbon fuel in a highly enriched state, thereby producing a stable lean state in the main engine using the reformed fuel. This system is characterized in that it performs combustion to reduce air pollution components in exhaust gas, and also makes it possible to utilize the output of an auxiliary engine as a fuel reformer.

In addition, the present invention solves the problem that hydrogen generation associated with reforming tends to cause backfire, and at the same time improves cylinder filling efficiency. The fuel reformer is connected separately, and the fuel reformer is constructed of a two-stroke engine which is suitable for reforming fuel and has a simple structure.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In FIG. 1, a main engine 1 operated with reformed fuel is a fuel reformer for reforming general-purpose hydrocarbon liquid fuel. It is equipped with an auxiliary engine 2 as a device. The main engine 1 has a configuration similar to that of a well-known four-stroke engine, and has cylinders 3 and 3.
A piston 4 reciprocating within the cylinder 3 is connected to a crank 6 via a connecting rod 5.
A reformed fuel supply pipe 7, an intake pipe 8 for sucking only air, and an exhaust pipe 9 are connected to the head of the unit, and a reformed fuel supply valve 1 opens and closes each of these pipes.
0, an intake valve (not shown), and an exhaust valve 11. Note that 12 in the figure is a spark plug.

On the other hand, the auxiliary engine 2 has a configuration similar to that of a well-known two-stroke engine, in which a piston 14 that reciprocates within a cylinder 13 is connected to a crank 16 via a connecting rod 15, and supplies gasified fuel along with air. A mixture supply pipe 17 for discharging the reformed fuel reformed in the cylinder 13 and a fuel discharge pipe 18 for discharging the reformed fuel reformed in the cylinder 13 are opened on the side of the cylinder. The liquid fuel from the fuel tank is heated in a heat exchanger 19 in the exhaust pipe 9 of the main engine 1 to become fuel gas, which is supplied in a highly concentrated state of approximately twice the stoichiometric mixing ratio. Further, the reformed fuel discharge pipe 18 is communicated with the reformed fuel supply pipe 7 of the main engine 1. Note that 20 in the figure is a spark plug.

In the auxiliary engine having such a configuration, liquid fuel from the fuel tank is heated by the exhaust gas of the main engine 1 in the heat exchanger 19, becomes fuel gas, and flows into the mixture supply pipe 1 together with air in a highly concentrated state.
7 to the cylinder 13, where it is partially combusted to drive the piston 14 and at the same time reformed by generating hydrogen and carbon monoxide through thermal decomposition. This reformed fuel gas is passed from the discharge pipe 18 to the reformed fuel supply pipe 7 of the main engine 1 to the cylinder 3.
The combustion gas is mixed with air from the intake pipe 8 and combusted to drive the piston 4, and then the combustion gas is exhausted from the exhaust pipe 9.

The reformed fuel gas supplied to the main engine 1 contains hydrogen and carbon monoxide, so it has good ignition and a high flame propagation speed, allowing stable lean combustion to occur. Emissions of air polluting components can be suppressed.

The auxiliary engine mentioned above is mainly used for reforming fuel, but its output can be used; in this case, the output of the auxiliary engine can be extracted along with the output of the main engine 1 to a single drive shaft. or both outputs can be taken separately.

Note that the auxiliary engine 2 is a two-stroke engine that is advantageous for burning rich fuel, and the main engine 1 is a four-stroke engine. When connected directly to the pipe 7, the supply valve 10 of the main engine is closed at the time the reformed fuel is discharged from the discharge pipe 18, so that the rotational speed of the auxiliary engine is 1/2 that of the main engine. You need to set the timing to open. However, if a surge tank is provided between the discharge pipe 18 and the supply pipe 7, this is not necessary.

According to the fuel lean burn engine of the present invention, the auxiliary engine is used as a fuel reformer for reforming general-purpose hydrocarbon fuel, and the main engine is powered by the reformed fuel. This makes it possible to achieve stable lean combustion and to sufficiently suppress emissions of air polluting components compared to current engines.Furthermore, the fuel is reformed by an auxiliary engine. , it is possible to extract output from the auxiliary engine without dissipating all of the generated heat as in conventional reformers, and it is also a simpler and cheaper device than when reforming fuel using a catalyst. can be provided.

Furthermore, as mentioned above, since the reformed fuel gas contains hydrogen, there is a problem that flashback is likely to occur.However, in the present invention, the reformed fuel gas is directly supplied to the cylinder from an independent supply pipe without being mixed with air. Since the reformed fuel is supplied, backfire can be prevented, and filling efficiency can also be improved by setting the timing to supply the reformed fuel after the intake valve closes.

Furthermore, the auxiliary engine used as a fuel reformer needs to be operated in a fuel-enriched state that is at least twice the stoichiometric mixture ratio, but operation under such conditions is not possible with the two-stroke engine adopted in the present invention. While this can be easily achieved, it is difficult to achieve this using other means, such as a four-stroke engine. This is considered to be because in the case of a 2-cycle engine, there is more residual gas from the previous cycle than in the case of a 4-cycle engine, and the temperature of the mixture before combustion becomes higher. Moreover, when using a 2-stroke engine as a normal engine, it is impossible to avoid the emission of unburned gas due to blow-through, and the efficiency cannot be achieved. When used as a reformer, they do not pose any particular drawbacks; for example, even if fuel blows through, it is re-burned in the main engine, so there is no problem. Further, since the two-stroke engine uses a piston instead of the valve mechanism, it is extremely advantageous in that it has a simple structure and can be provided at low cost. Therefore, by performing fuel reformation using a two-stroke engine as in the present invention, effective operation can be achieved with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the engine of the present invention. 1...Main engine, 2...Auxiliary engine, 3,
13... Cylinder, 7... Reformed fuel supply pipe, 8...
...Intake pipe, 9...Exhaust pipe, 17...Mixture supply pipe, 18...Fuel discharge pipe.

Claims (1)

[Claims] 1. The main engine is configured as a 4-cycle engine, with a reformed fuel supply pipe, an intake pipe that sucks only air, and an exhaust pipe connected to the head of the cylinder, while the main engine is configured as a 2-stroke engine, with a gas pipe connected to the side of the cylinder. An auxiliary engine is attached as a fuel reforming device, which has an air-fuel mixture supply pipe that supplies the enriched fuel with air and a fuel discharge pipe that discharges the reformed fuel reformed in the cylinder. An engine equipped with a fuel reformer characterized in that a fuel discharge pipe of the engine is connected to a reformed fuel supply pipe of the main engine.