DE2941771C2 - Internal combustion engine operated with alcohol as the operating fuel, in particular for commercial vehicles - Google Patents

Description

circulating pump 23 is provided, the water circuit over the line 21 opens into the pipe 17 and is also passed through the exhaust gas heat exchanger 18 is and the heat exchanger 19 of the evaporator 4 flows through. By an outgoing line 20 Branch line 24 is the connection to the circulation pump 23 and thus the water circuit 21 is closed.

For the cold start of the internal combustion engine 11 is a container 25 with starting fuel, such as. B. Methane (Eidgas), Propane et al. provided, which under prevailing normal pressure and temperature conditions is gaseous This fuel tank 25 is via an interposed reducing and switching valve 26 in a line 27 is connected directly to the upper part of the evaporator 4. The cold internal combustion engine 11 can be controlled on the flow side on Output of the evaporator 4 arranged thermostat 29 open the line 27, so that the starting fuel the upper part of the evaporator 4 is supplied and the internal combustion engine is started immediately, that is, without a preheating time can be.

The starting fuel of the internal combustion engine 11 is

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A temperature sensor 30 is provided in the pipeline 17, which when the operating temperature is reached of the internal combustion engine 11 switches off the circulation pump 23 and thus sets the water circuit 21, 20, 24 s; tü'-sets.

1 sheet of drawings

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Claims (1)

Claim: Internal combustion engine operated with alcohol as the operating fuel, especially for commercial vehicles, with a thermostat-controlled cooling water circuit containing a water pump and switching valves, with an evaporator for the fuel that can be heated by the cooling water circuit, with a in addition to the second fuel tank that receives the operating fuel Fuel tank for starting fuel for starting the internal combustion engine from temperatures below the operating temperature, which is an alternative to the fuel supply of the internal combustion engine can be connected to the operating fuel via a reducing and switching valve, and with an am Outlet of the evaporator arranged, the water temperature determining thermostat, the at least indirectly actuates the reducing and switching valve in such a way that when the cooling water is at operating temperature the operating fuel and, at a lower temperature, the starting fuel is switched on, furthermore with one arranged in the cooling water circuit upstream of the evaporator, of exhaust gases from the internal combustion engine pressurized exhaust gas heat exchanger, characterized in that behind the evaporator (4) and behind which the water temperature locking thermostat (29) a branch line returning to the exhaust gas heat exchanger (18) (24) for cooling water goes off, which has a separate, independently driven circulating pump (23) as well as a further exhaust gas heater (22), and the drive of the circulating pump (23) in the manner with a thermostat (30) in the connecting line (17) between the engine cooling water circuit (12, 12 ', 13) and the exhaust gas-heated water circuit (17, 21, 24) is coupled that with a thermostatic valve (16) in the engine cooling water circuit (12, 12 ') open and thus of hot cooling water through the connecting line (17), the circulation pump (23) is stopped and vice versa. The invention relates to an internal combustion engine operated with alcohol as the operating fuel, in particular for commercial vehicles, according to the preamble of claim 1. From DE-OS 27 28 039 an internal combustion engine is known, which operated either with gasoline or alcohol can be. Both types of fuel are stored in separate storage tanks, with the fuel selection can be set by the driver on a selector switch for engine operation. When running on petrol the liquid fuel from the reservoir is fed directly to a carburetor in a conventional manner fed. For operation with alcohol, the engine is equipped with an evaporator in which the liquid Alcohol with a cold start by an electric heater and from a certain cooling water temperature from Cooling water is evaporated. Since a cold start with alcohol takes a certain amount of time before the cooling water Alcohol can evaporate, the evaporation energy must be applied by the electric heater by then will. However, this requires a considerable load on the vehicle battery, which is particularly important for this purpose must be dimensioned large so that their energy both for the actual starting process as well as for the heating of the evaporator is sufficient It is also known from US-PS 19 91 021, an internal combustion engine optionally with kerosene as fuel operate in liquid or the same fuel in gaseous state. The liquid fuel is evaporated in a gas generator operated with exhaust gas heat and in a special gas storage tank ίο The evaporation of the fuel is collected by a thermostatic valve arranged in the fuel supply line to the gas generator controlled by the internal temperature of the gas generator Special structural measures to shorten the Operation with liquid fuel in the starting phase is not provided. The invention is based on the object during operation of a generic internal combustion engine, the starting phase until the internal combustion engine is switched over keep from starting fuel to operating fuel as short as possible. The object is achieved according to the invention by the characterizing features in claim 1.
The invention achieves that, on the one hand, the evaporator for the operating fuel and, on the other hand, the engine are heated up quickly. This is because the evaporator and motor are operated with short-circuited cooling water circuits in the starting phase of the internal combustion engine, with heat from the engine exhaust gas being supplied to the circuit for the evaporator and as little heat as possible being dissipated in the cooling water circuit. The invention will be explained in more detail using an exemplary embodiment shown in the drawing. The figure shows a circuit diagram of an alcohol gas engine according to the invention. In the circuit diagram for an alcohol gas engine shown in the figure, the liquid fuel arrives from a fuel tank 1, conveyed by means of a fuel pump 2, through a fuel supply line 3 in a fuel vaporizer 4. By a fuel pump 2 and fuel vaporizer 4 arranged between Overflow valve 5 can return too much fuel to the fuel tank via a line 6 1 flow back. From the fuel vaporizer 4, vaporized, i.e. gaseous, fuel arrives via a pipe system 7 to the Air / gas mixer 8 and via an intake 9 with throttle valve 10, to the cylinders of an internal combustion engine 11th The engine cooling water circuit 12 of the internal combustion engine 11, with its own water pump 13, can in on is switched via a vehicle radiator 15 in a known manner by means of a thermostat 14 as a function of temperature will. In the engine cooling water circuit 12, 12 ', a thermostatic valve 16 is also provided, which as 3/2-way valve is formed and switch the cooling water circuit of the internal combustion engine 11 in such a way can that the cooling water is passed via a pipe 17 to an exhaust gas heat exchanger 18, which the heat exchanger 19 of the evaporator 4 is connected upstream. Via an outgoing from the heat exchanger 19 Bypass line 20 is the engine cooling water circuit 12, 17, 20 flowing back again with the water pump 13 connected. In addition to the engine cooling water circuit 12, 17, 20 is another water circuit 21, 20, 24 with its own I Jm-