Bi-fuel liquid injection system for an internal combustion engine

• US 6,035,837 A
• Filed: 12/04/1998
• Issued: 03/14/2000
• Est. Priority Date: 11/06/1998
• Status: Expired due to Fees

• Current Assignee: Siemens Automotive Corporation (Siemens AG)
• Original Assignee: Siemens Automotive Corporation (Siemens AG)
• Inventors: Wright, Danny O., Cohen, Jim
• Primary Examiner(s): Argenbright, Tony M.
• Assistant Examiner(s): HAIRSTON, BRIAN J
• Application Number:
  US09/205,207
• Time in Patent Office: 466 Days
• Field of Search: 123/525, 123/575, 123/576, 123/276 E, 123/1 A
• US Class Current: 123/575
• CPC Class Codes: F02D 19/0621 Purging of the fuel system
• CPC Class Codes: F02D 19/0628 Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position
• CPC Class Codes: F02D 19/0636 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 19/0676 Multi-way valves; Switch-over valves
• 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 19/0694 operating with a plurality of fuels
• CPC Class Codes: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A bi-fuel injection system includes a source of first liquid fuel; a source of second liquid fuel; at least one variable vapor pressure fuel injector; a common fuel rail for supplying first or second fuels to the fuel injector; a first valve structure in selective communication with the source of first or second fuels and in communication with an inlet of the fuel rail to selectively control supply of one of the first and second fuels to the fuel rail; and a second valve structure in communication with an outlet of the fuel rail and in selective communication with the source of first or second fuels to return fuel exiting the fuel rail to the source of first or second fuels. The second valve structure may be in selective communication with a vapor purge system to receive fuel vapors exiting the fuel rail. The first and second valve structures are selectively controllable (1) to permit residual first fuel to be purged from the fuel rail into one of the sources of first and second fuels when supplying the second fuel to the fuel rail, and (2) to permit residual second fuel to be purged from the fuel rail into the vapor purge system or one of the sources of first and second fuels when supplying the first fuel to the fuel rail.

Claims

1. A bi-fuel, variable vapor pressure injection system for an internal combustion engine, comprising:

a source of first liquid fuel;

a source of second liquid fuel;

at least one variable vapor pressure fuel injector;

a common fuel rail for supplying one of said first and second fuels to said at least one fuel injector;

a first valve structure in selective communication with each of said sources of said first and second fuels and in communication with an inlet of said fuel rail to selectively control supply of one of said first and second fuels to said fuel rail; and

a second valve structure in communication with an outlet of said fuel rail and in selective communication with said source of second fuel to return fuel exiting said fuel rail to said source of second fuel, said second valve structure being in selective communication with a vapor purge system to receive fuel vapors exiting said fuel rail,

said first and second valve structures being selectively controllable (1) to permit residual first fuel to be purged from said fuel rail into said source of second fuel when supplying said second fuel to said fuel rail, and (2) to permit residual second fuel to be purged from said fuel rail into said vapor purge system when supplying said first fuel to said fuel rail.

2. The system according to claim 1, further comprising a valve associated with said source of second fuel to permit said second fuel to exit said source of second fuel.

3. The system according to claim 2, wherein said valve is a one-way solenoid valve.

4. The system according to claim 3, wherein each of said first and second valve structures comprises a three-way solenoid valve.

5. The system according to claim 4, further including an electronic control unit associated with said valve and said first and second valve structures to electrically control said valve and said first and second valve structures.

6. The system according to claim 5, further including a pressure sensor and a temperature sensor, each of said sensors being associated with said fuel rail to monitor a temperature and a pressure of a mixture of fuel in said fuel rail, each of said sensors being operatively associated with said electronic control unit, said electronic control unit being constructed and arranged to calculate proportions of said first and said second fuels in said mixture based on said pressure and temperature of said mixture of fuel in said fuel rail.

7. The system according to claim 1, wherein each of said first and second valve structures comprises a three-way solenoid valve.

8. The system according to claim 1, further comprising bypass structure between said first valve structure and said source of second fuel, said bypass structure being constructed and arranged to permit liquid second fuel from said source thereof to move second fuel in the form of vapor to said source of second fuel, when switching from supplying said second fuel to said fuel rail to supplying said first fuel to said fuel rail.

9. The system according to claim 1, wherein a return line is in communication with said second valve structure and in communication with said vapor purge system, said return line being constructed and arranged to return excess first fuel exiting said fuel rail to said source of first fuel and to direct fuel vapor to said vapor purge system.

10. The system according to claim 9, further including a fuel pressure regulator in said return line.

11. The system according to claim 9, wherein said source of first fuel is a fuel tank and said vapor purge system is associated with said fuel tank.

12. The system according to claim 1, wherein a vapor recovery line is in communication with said second valve structure, said vapor purge system being in communication with said vapor recovery line.

13. The system according to claim 1, wherein a plurality of fuel injectors are provided.

14. A bi-fuel injection system comprising:

a source of first liquid fuel;

a source of second liquid fuel;

at least one variable vapor pressure fuel injector;

a common fuel rail for supplying one of said first and second fuels to said at least one fuel injector;

a first three-way solenoid valve to selectively control supply of one of said first and second fuels to said fuel rail, said first three-way valve having a first port in continuous communication with an inlet to said fuel rail, a second port in selective communication with said source of second fuel, and a third port in selective communication with said source of first fuel;

a second three-way solenoid valve having a first port in continuous communication with an outlet of said fuel rail, a second port in selective communication with said source of second fuel to return fuel exiting said fuel rail to said source of second fuel, and a third port in selective communication with a vapor purge system to receive fuel vapors exiting said fuel rail; and

an electronic control unit operatively associated with each of said three-way valves to control operation thereof;

said first and second three-way valves being selectively controllable (1) to permit residual first fuel to be purged from said fuel rail through said second port thereof and into said source of second fuel, when supplying said second fuel to said fuel rail via said second port of said first three-way valve, and (2) to permit residual second fuel to be purged from said fuel rail through said third port thereof and into said vapor purge system, when supplying said first fuel to said fuel rail via said third port of said first three-way valve.

15. The system according to claim 14, further comprising bypass structure between said second port of said first three-way valve and said source of second fuel, said bypass structure being constructed and arranged to permit liquid second fuel from said source thereof to move second fuel in the form of vapor to said source of second fuel, when switching from supplying said second fuel to said fuel rail to supplying said first fuel to said fuel rail.

16. The system according to claim 14, wherein a return line is connected to said third port of said second three-way valve for returning excess fuel exiting said fuel rail to said source of first fuel, said vapor purge system being fluidly coupled to said return line.

17. The system according to claim 16, further including a fuel pressure regulator in said return line.

18. The system according to claim 14, wherein a vapor recovery line is connected to said third port of said second three-way valve, said vapor purge system being fluidly coupled to said vapor recovery line.

19. The system according to claim 14, further including a pressure sensor and a temperature sensor, each of said sensors being associated with said fuel rail to monitor a temperature and a pressure of a mixture of fuel in said fuel rail, each of said sensors being operatively associated with said electronic control unit, said electronic control unit being constructed and arranged to calculate proportions of said first and said second fuels in said mixture based on said pressure and temperature of said mixture of fuel in said fuel rail.

20. A bi-fuel, variable vapor pressure injection system for an internal combustion engine, comprising:

a source of first liquid fuel;

a source of second liquid fuel;

at least one variable vapor pressure fuel injector;

a common fuel rail for supplying one of said first and second fuels to said at least one fuel injector;

a first valve structure in selective communication with each of said sources of said first and second fuels and in communication with an inlet of said fuel rail to selectively control supply of one of said first and second fuels to said fuel rail; and

a second valve structure in communication with an outlet of said fuel rail and in selective communication with each of said sources of first and second fuels,

said first and second valve structures being selectively controllable (1) to permit residual first fuel to be purged from said fuel rail into one of said sources of first and second fuels when supplying said second fuel to said fuel rail, and (2) to permit residual second fuel to be purged from said fuel rail into one of said sources of first and second fuels when supplying said first fuel to said fuel rail.

21. A method of selectively supplying first and second hydrocarbon fuels from respective sources to an internal combustion engine, comprising:

providing a common fuel rail to supply at least one variable vapor pressure fuel injector with one of the first and second fuels;

providing a first valve structure in selective communication with each of the sources of fuel and in communication with an inlet of said fuel rail;

providing a second valve structure in communication with an outlet of said fuel rail and in selective communication with the source of second fuel to return fuel exiting said fuel rail to said source of second fuel, said second valve structure being in selective communication with a vapor purge system to receive fuel vapors exiting said fuel rail; and

controlling said first and second valve structures (1) to permit residual first fuel to be purged from said fuel rail into said source of second fuel when supplying said second fuel to said fuel rail, and (2) to permit residual second fuel to be purged from said fuel rail into said vapor purge system when supplying said first fuel to said fuel rail.