Internal combustion engine adapted to operate selectively with injection of gasoline or LPG

• US 5,592,924 A
• Filed: 02/05/1996
• Issued: 01/14/1997
• Est. Priority Date: 02/03/1995
• Status: Expired due to Fees

• Current Assignee: Centro Ricerche Fiat Societa' Consortile Per Azioni
• Original Assignee: Centro Ricerche Fiat Societa' Consortile Per Azioni
• Inventors: Audisio, Filippo, Gianotti, Pietro, Gozzelino, Riccardo, Borello, Gianpiero, Ferrera, Massimo
• Primary Examiner(s): Solis, Erick R.
• Application Number:
  US08/596,478
• Time in Patent Office: 344 Days
• Field of Search: 123/525, 123/575
• US Class Current: 123/525
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02B 43/00 Engines characterised by operating on gaseous fuels; Plants including such engines engines characterised by the gas-air charge being ignited by compression ignition of an additional fuel F02B7/06; engines convertible from gas to other fuel consumption F02B69/04
• CPC Class Codes: F02B 69/04 for gaseous and non-gaseous fuels
• CPC Class Codes: F02D 19/0605 to adjust the fuel pressure or temperature
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• CPC Class Codes: F02D 19/0631 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 19/0647 the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
• CPC Class Codes: F02D 19/0684 High pressure fuel injection systems; Details on pumps, rails or the arrangement of valves in the fuel supply and return systems
• CPC Class Codes: F02D 19/0692 Arrangement of multiple injectors per combustion chamber
• CPC Class Codes: F02M 21/0281 Adapters, sockets or the like to mount injection valves onto engines; Fuel guiding passages between injectors and the air intake system or the combustion chamber
• CPC Class Codes: F02M 21/0287 characterised by the transition from liquid to gaseous phase F02M21/06 takes precedence; Injection in liquid phase; Cooling and low temperature storage
• CPC Class Codes: F02M 61/145 the injection nozzle opening into the air intake conduit
• CPC Class Codes: F02M 69/465 of fuel rails
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

There is described an internal combustion engine able to operate selectively either with gasoline injection or with injection of LPG in a liquid state, which is obtained from an engine able to operate only with gasoline injection.

Claims

1. Internal combustion engine, provided with a gasoline feed system, including many gasoline injection devices which are respectively associated with the cylinders of the engine, and an LPG feed system, including many LPG injection devices respectively associated with the cylinders of the engine, said engine being adapted to operate selectively with gasoline or LPG injection, characterized by the combination of the following features:

the engine includes, for each cylinder, an adaptor member provided both with a seat for a gasoline injector, and with a seat for an LPG injector, said adaptor member having an inner cavity communicated to said seats and opening into an outlet hole, said outlet hole being formed through a portion of said adaptor member which is to be fitted within a seat of the engine originally provided for receiving the gasoline injection device, said engine further comprising a distributing conduit or rail for feeding LPG to all the LPG injection devices,

the LPG feed system comprises;

the plurality of said LPG injectors respectively associated with the various cylinders of the engine,

said distributing conduit or rail for feeding LPG to the injectors, separate from the gasoline feed rail,

an LPG reservoir,

means for feeding LPG from the reservoir to the feed rail while keeping the LPG in a liquid state, said means including a pump which takes LPG from the reservoir and feeds it to the rail,

a re-flow conduit for returning the quantity of LPG fed in excess to the injectors into the reservoir,

a pressure adjuster, interposed in the reflow conduit for throttling this conduit so that said pump provides an increase from the pressure of LPG within the reservoir up to the pressure at which LPG is fed to the injectors,

means associated with said pressure adjuster, able to detect the pressure of LPG within the reservoir, which is a function of the temperature, and to vary as a consequence the degree of throttling of the adjuster so as to keep said pressure increase at a substantially constant level,

sensor means of the LPG feed pressure to the injectors, and

electronic control means which receives output signals from said sensor means of the injector feed pressure and controls as a consequence the time during which the injectors remain open.

2. Internal combustion engine according to claim 1, characterized in that for each cylinder of the engine there is provided an adaptor member including a one-piece first element, including said portion with the outlet hole and the seat of the gasoline injection device, and a second element including the seat for the LPG injection device, located at a distance from the first element and connected thereto by a connecting tube which communicates the outlet hole of the first element to the seat of the LPG injection device formed in the second element.

3. Internal combustion engine according to claim 1, characterized in that for each cylinder of the engine there is provided an adaptor member including the said portion with the outlet hole and both said seats of the gasoline injection device and the LPG injection device.

4. Internal combustion engine according to claim 2, characterized in that said second elements of the adaptor members associated with the various cylinders of the engine are formed, either all together, or in groups, in a single structure including also a cavity acting as a distributing conduit or rail for feeding LPG.

5. Internal combustion engine according to claim 3, characterized in that said LPG feed rail is formed by an element separate from the adaptor members, each of which is connected thereto by means of a connecting tube.

6. Internal combustion engine according to claim 2, characterized in that each connecting tube is a hose of rubber or the like, whose ends are fitted on cooperating nipples provided at the connected elements.

7. Internal combustion engine according to claim 1, characterized in that said electronic control means comprises a first electronic control unit of a type conventionally used in gasoline injection systems, for controlling the gasoline injection, and a second electronic control unit able to modify the mode of operation of the first electronic control unit as a function of the characteristics of the LPG which is fed, for controlling the LPG injection yet by said first electronic control unit.

8. Internal combustion engine according to claim 1, characterized in that said pump is arranged inside the LPG reservoir.

9. Internal combustion engine according to claim 7, characterized in that it comprises sensor means of the rotational speed of the engine shaft, comprising a phonic wheel, and in that said electronic control means of the injectors are programmed to carry out the injection at a first cylinder, after starting of the engine, when a first signal from the phonic wheel is received and to control in sequence thereafter, at regular intervals from the first injection, the injection into the other cylinders of the engine, said system being therefore deprived of means for providing a predetermined timing of the injection with respect to the angular position of the engine shaft.

10. Internal combustion engine according to claim 5, characterized in that each connecting tube is a hose of rubber or the like, whose ends are fitted on cooperating nipples provided at the connected elements.