Internal-combustion engines – Charge forming device – Combined liquid and gaseous fuel
Reexamination Certificate
1999-06-14
2001-07-31
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Charge forming device
Combined liquid and gaseous fuel
C123S0270GE
Reexamination Certificate
active
06267105
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pressure reducer for internal combustion engines fed with liquid petroleum gasses; the reducer essentially comprises a valve for intercepting the liquid petroleum gas flow, a heat exchanger consisting of a first section in which the liquid gas is heated by means of the heat of the engine cooling water and a second section for heating the liquid gas with electrical resistors, an evaporation chamber, a device for regulating the gas pressure, an electronic central for controlling said pressure, gas absolute pressure sensors located at the outlet of the device for regulating the gas pressure, pressure sensors in the intake manifold of the engine and gas temperature sensors.
STATE OF THE TECHNIQUE
EP-A-0 526 410 refers to self-compensated and electrically heated reducer for compressed gas or l.p.g.
The reducer comprises: a supporting body, a chamber formed inside the body; a diaphragm; an opening inlet between an entrance and the chamber; a closing mechanism for an opening inlet controlling the flow of fuel owing to the action of manoeuvring elements, mechanically connected to the diaphragm, on the device controlling the fuel pressure coming out of the bottle; a mechanism which acts on at least one of the manoeuvring elements to cancel the resultant of the action of the fuel pressure on the mechanism; electrical resistors connected with the feeding system in the engine placed in thermal contact with the walls of the body near the inlet.
In this and other available prior art documents pressure reducers are described which mainly present the following disadvantages:
A—The pressure is reduced by means of mechanical apparatuses, preferably fitted with diaphragms; in these apparatuses devices are not provided which verify if the fuel pressure has been reduced to the optimal value for feeding the engine;
B—The diaphragms are used both in the first stage of the reducer for obtaining a first pressure reduction from the value reached after the vaporisation to the outlet value from the first stage, and in the second stage for a second pressure reduction from the outlet value from the first stage to a value allowing the feeding of the engine;
C—The engine feeding pressure depends on both the first and second reduction effected, respectively, by the diaphragms of the first and the second stage; since the diaphragm of the first stage is not capable of reducing the gas pressure from the vaporisation value to a convenient outlet value from the first stage with precision and reproducibility, the feeding pressure is subject to errors depending on the errors of the diaphragm of the first stage;
D—The heat exchangers used for vaporising the fuel consist of electrical resistors placed in thermal contact with the walls of the first stage body near the inlet of the second stage; therefore, their function is limited to heating the fuel during the engine warm up; in the subsequent engine working phases at stabilised temperature, during which the heating can be the cause for a greater evaporation efficiency, the known heat exchangers do not work.
AIMS AND FEATURES OF THE INVENTION
The purpose of this invention is to obviate these disadvantages.
The invention, as claimed, solves the problem of creating an electronic pressure reducer for liquid petroleum gasses. The reducer is fitted with a first stage in which a reducing valve is found for reducing the fuel pressure from the vaporisation value to an outlet value from the first stage; the pressure reducing valve is controlled by a central unit with electronic components in order to obtain pressure values suitable for the different working phases of the engine at the outlet of the first stage with reproducibility.
The advantages reached by using the reducer according to the invention are mainly due to the fact that a heat exchanger is located upstream of the entrance of the first stage so that the fuel is heated before entering the first stage; this particularity of the reducer allows a greater evaporation efficiency than the efficiency reached by the reducer disclosed by EP-A-0 526 410, in which a heat exchanger is used consisting of electrical resistors placed in thermal contact with the walls of the body near the inlet orifice of the second stage.
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Bradley Arant Rose & White LLP
Huynh Hai
Kamen Noah P.
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