Internal-combustion engines – Charge forming device – Gaseous fuel and air mixer
Patent
1982-10-27
1986-03-11
Cross, E. Rollins
Internal-combustion engines
Charge forming device
Gaseous fuel and air mixer
123577, F02B 4300
Patent
active
045747636
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a system for use with a conventional internal combustion engine, such as an automobile engine, to permit alternative utilization of a liquid fuel such as gasoline and a liquified gas fuel such as liquified petroleum gas, natural gas, hydrogen or propane.
BACKGROUND AND ADVANTAGES OF THE INVENTION
Dual fuel systems are well known. Such systems typically consist of a means for selecting the fuel to be utilized, a liquified-to-gaseous fuel converter or vaporizer, and a mixer for gaseous fuel and air.
Typically, such systems utilize electrically operated solenoid valves for the alternative selection of fuels, e.g., one valve in the liquid propane line between the propane storage tank and the inlet to the converter or vaporizer, and another in the gasoline line supplying the carburetor. These solenoid valves are typically activated by a switch mounted for convenient operation by the vehicle driver. However, they frequently do not work well in the environment of the engine, i.e., it is difficult to locate a reliable voltage source in the vehicle's electrical system which is the right voltage, which is available during engine starting and which does not adversely affect the engine ignition system. In addition to the electrical lock-offs for each type of fuel, a vacuum or oil pressure safety switch is generally required. In one aspect, the present invention obviates electrical problems of this type by utilizing a single mechanically operated valve structure with a vacuum lock-off valve in the converter.
Liquified petroleum gas, propane and the other "gaseous" fuels are normally held in a tank under sufficient pressure and at a temperature to remain in a liquid state, and are herein referred to as "liquified gas" fuels. Conversion of such liquified fuel to a gaseous state at a suitable pressure and temperature is accomplished in the converter or vaporizer.
Known converters are generally of the two stage variety. The first stage generally includes a small diameter first stage diaphragm within a chamber warmed by hot engine coolant to actuate a normally open liquified gas inlet valve, and the second stage generally includes a large diameter diaphragm to actuate a normally closed valve responsive to engine demand to supply fuel. However, the converter in some systems (such as disclosed in U.S. Pat. No. 3,528,787 dated Sept. 15, 1970 and assigned to the assignee of this application) utilized a single diaphragm responsive to engine demand but operable at a positive pressure to supply gaseous fuel. Such system continued to use a solenoid operated fuel lock-off valve. In addition, the operating pressure to which such systems were regulated was not variable in response to engine demand.
In another aspect, the converter of the present invention provides a positive "lock off" of gaseous fuel to the converter, combines the two valve functions in a single structure and utilizes two diaphragms of equal size thereby realizing ecomony of manufacture and increased interchangeability of parts. In addition, the utilization of a large fuel inlet valve diaphragm results in very quick starting capability because relatively little drop in intake manifold pressure is required to activate the inlet valve. This reduces the problems common with the low engine starting speeds and the resultant small drop in manifold pressure normally experienced during cold weather conditions.
In another aspect, the converter of the present invention modulates the positive pressure at which gaseous fuel is applied to the mixer as a function of engine demand. A simple mechanical adjustment of the modulator then provides a power adjustment for different fuels.
In the "gasoline" mode, the converter vacuum line is opened to the atmosphere and the consequent absence of pressure differential on the liquified fuel inlet diaphragm of the converter effects a positive lock-off of the liquified fuel inlet valve permitting the conventional carburetor to function in a normal fashion, i.e. with air passing thr
REFERENCES:
patent: 3015548 (1962-01-01), McClain
patent: 3528787 (1970-09-01), Hallberg
patent: 3741737 (1973-06-01), Jones
patent: 4020810 (1977-05-01), Baverstock
Cross E. Rollins
PetroSystems International, Inc.
Rogers, III L. Lawton
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