Fuel system

• US 9,234,468 B2
• Filed: 12/21/2012
• Issued: 01/12/2016
• Est. Priority Date: 12/21/2012
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Coldren, Dana Ray
• Primary Examiner(s): Huynh, Hai
• Assistant Examiner(s): NAJMUDDIN, RAZA NEHAL
• Application Number:
  US13/724,544
• Publication Number:
  US 20140174404A1
• Time in Patent Office: 1,117 Days
• Field of Search: 123/459
• US Class Current: 1/1
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• CPC Class Codes: F01N 2610/06 the substance being in the gaseous form
• CPC Class Codes: F01N 2610/10 the substance being heated, e.g. by heating tank or supply line of the added substance
• CPC Class Codes: F01N 2900/1808 Pressure
• CPC Class Codes: F01N 3/0253 adding fuel to exhaust gases
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F01N 3/106 Auxiliary oxidation catalysts
• CPC Class Codes: F01N 3/36 Arrangements for supply of additional fuel
• CPC Class Codes: F02D 19/0605 to adjust the fuel pressure or temperature
• 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 19/0647 the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
• CPC Class Codes: F02D 19/0673 Valves; Pressure or flow regulators; Mixers
• CPC Class Codes: F02M 21/0224 Secondary gaseous fuel storages
• 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: Y02T 10/30 Use of alternative fuels, e.g. biofuels

Abstract

A fuel system for a dual fuel power source includes a first fuel circuit fluidly connected to the power source, a second fuel circuit separate from the first fuel circuit and fluidly connected to the power source, and a pressure regulator fluidly connected to the first fuel circuit. The pressure regulator is configured to vent a first fuel from the first fuel circuit to an aftertreatment system fluidly connected to the power source in response to a pressure difference between the first and second fuel circuits being less than or equal to a pressure difference threshold.

Claims

1. A fuel system for a dual fuel power source, comprising:

a first fuel circuit fluidly connected to the power source;

a second fuel circuit separate from the first fuel circuit and fluidly connected to the power source; and

a pressure regulator fluidly connected to the first fuel circuit, the pressure regulator configured to vent a first fuel from the first fuel circuit to an aftertreatment system fluidly connected to the power source in response to a pressure difference between the first and second fuel circuits being less than or equal to a pressure difference threshold.

2. The fuel system of claim 1, wherein the aftertreatment system includes an accumulator, the pressure regulator being configured to vent the first fuel to the accumulator in response to the pressure difference between the first and second fuel circuits being less than or equal to the pressure difference threshold.

3. The fuel system of claim 2, wherein the aftertreatment system further includes a regeneration device and a particulate filter configured to condition exhaust received from the power source, the accumulator configured to direct the first fuel to the regeneration device.

4. The fuel system of claim 3, wherein the regeneration device is configured to combust the first fuel in response to a pressure of the accumulator being greater than an accumulator pressure threshold.

5. The fuel system of claim 1, wherein the first fuel circuit is fluidly connected to the power source via a first passage and the second fuel circuit is fluidly connected to the power source via a second passage,

the pressure difference comprising a difference between a fluid pressure of the first passage and a fluid pressure of the second passage.

6. The fuel system of claim 5, wherein the first fuel comprises natural gas and the second fuel comprises diesel, the pressure regulator being configured to maintain the fluid pressure of the second passage greater than the fluid pressure of the first passage.

7. The fuel system of claim 1, wherein the pressure regulator is fluidly connected to the second fuel circuit.

8. The fuel system of claim 1 further including a first accumulator fluidly connected to the first fuel circuit, the first accumulator being configured to store the first fuel and to direct the first fuel to the power source via the pressure regulator.

9. The fuel system of claim 8, wherein the aftertreatment system includes a second accumulator fluidly connected to the first accumulator, the first accumulator being configured to direct the first fuel to the second accumulator in response to a pressure of the second accumulator being less than a second accumulator pressure threshold.

10. The fuel system of claim 1, further including a heat exchanger fluidly connected to the first fuel circuit, the heat exchanger being configured to increase a temperature of the first fuel upstream of the pressure regulator.

11. The fuel system of claim 10, further including a pump fluidly connected to the heat exchanger, the pump being configured to pressurize the first fuel and to direct the pressurized first fuel to the heat exchanger.

12. A fuel system for a dual fuel power source, comprising:

a first fuel circuit configured to supply a first fuel to a pressure regulator fluidly connected to the power source;

a second fuel circuit separate from the first fuel circuit, the second fuel circuit being configured to supply a second fuel, different than the first fuel, to the pressure regulator; and

an injector fluidly connected to the pressure regulator, the injector being configured to inject the first and second fuels into a combustion chamber of the power source, wherein

the pressure regulator is fluidly connected to an accumulator and configured to vent the first fuel, in gaseous form, to the accumulator in response to a pressure difference between the first and second fuel circuits being less than or equal to a pressure difference threshold.

13. The fuel system of claim 12, wherein the pressure regulator is configured to direct the first and second fuels to the power source, via the injector, in response to the pressure difference being greater than the pressure difference threshold.

14. The fuel system of claim 13, further including a heat exchanger fluidly connected to the first fuel circuit upstream of the pressure regulator, the heat exchanger being configured to change a phase of the first fuel from liquid to gas.

15. The fuel system of claim 14, further including an additional accumulator, the additional accumulator being fluidly connected to the heat exchanger and configured to store the first fuel, in gaseous form, upstream of the pressure regulator.

16. The fuel system of claim 15, wherein the additional accumulator is fluidly connected to the accumulator and configured to direct the first fuel to the accumulator, in gaseous form, in response to a pressure of the accumulator being less than an accumulator pressure threshold.

17. The fuel system of claim 12, wherein the power source is fluidly connected to a particulate filter and a regeneration device is fluidly connected to the particulate filter, the accumulator being configured to direct the first fuel to the regeneration device for combustion therein.

18. A method of operating a fuel system associated with a dual fuel power source, comprising:

directing a first fuel, in gaseous form, from a first fuel circuit to the power source;

directing a second fuel, different than the first fuel, from a second fuel circuit to the power source for combustion with the first fuel;

directing combustion exhaust from the power source through a particulate filter of an aftertreatment system fluidly connected to the power source;

venting the first fuel from the first fuel circuit to the aftertreatment system in response to a pressure difference between the first and second fuel circuits being less than or equal to a pressure difference threshold; and

combusting the vented first fuel in a regeneration device of the aftertreatment system to actively regenerate the particulate filter.

19. The method of claim 18, further including storing the vented first fuel in an accumulator of the aftertreatment system fluidly connected to the regeneration device, and

combusting the stored first fuel in the regeneration device in response to a pressure of the accumulator being greater than an accumulator pressure threshold.

20. The method of claim 18, wherein the first fuel comprises natural gas and the second fuel comprises diesel,

the method further including increasing a temperature of the natural gas in the first fuel circuit, wherein increasing the temperature changes a phase of the natural gas from liquid form to gaseous form, and

storing the natural gas, in gaseous form, in an accumulator of the first fuel circuit.