Dual-fuel fuel injection system for an internal combustion engine
A dual-fuel fuel injection system for an internal combustion engine has a liquid fuel injection branch and a gas fuel injection branch, in which a gas injector assembly that is controllable via a control fluid is situated. The liquid fuel forms the control fluid of the gas injector assembly.
1. A dual-fuel fuel injection system for an internal combustion engine, comprising:
a liquid fuel injection branch;
a liquid injector, fluidically connected to the liquid fuel injection branch;
a gas fuel injection branch;
a gas injector, fluidically connected to the gas fuel injection branch and comprising a control valve fluidically connected to the liquid fuel injection branch, and controllable by a control fluid to control gas flow provided by the gas fuel injection branch, wherein the control fluid comprises liquid fuel provided by the liquid fuel injection branch;
a first high-pressure pump configured for conveying the liquid fuel to the gas injector;
a second high-pressure pump configured for conveying the liquid fuel to at least the liquid injector; and
a switching device for selectively conveying the liquid fuel from the second high-pressure pump to the liquid injector or to the gas injector.
2. The dual-fuel fuel injection system of claim 1 , wherein the first high-pressure pump is configured to convey the liquid fuel to the gas injector during a gas operation.
3. The dual-fuel fuel injection system of claim 1 , wherein the second high-pressure pump comprises the switching device.
4. The dual-fuel fuel injection system of claim 1 , further comprising a pre-feed pump that is fluidically connected upstream from the first high-pressure pump and the second high-pressure pump.
5. The dual-fuel fuel injection system of claim 4 , wherein the first high-pressure pump and the second high-pressure pump are fluidically connected in parallel.
6. The dual-fuel fuel injection system of claim 4 , wherein the first high-pressure pump is configured to selectively convey the liquid fuel to the liquid injector or to the gas injector.
7. The dual-fuel fuel injection system of claim 1 , wherein the gas injector is fluidically connected to a liquid fuel tank by a leak return line.
8. An internal combustion engine comprising:
a liquid fuel injection branch;
a liquid injector, fluidically connected to the liquid fuel injection branch;
a gas fuel injection branch;
a gas injector in the gas fuel injection branch and comprising a control valve fluidically connected to the liquid fuel injection branch, that is controllable by a control fluid to control gas flow provided by the gas fuel injection branch, wherein the control fluid comprises liquid fuel provided by the liquid fuel injection branch;
a first high-pressure pump configured for conveying the liquid fuel to the gas injector during a gas operation;
a second high-pressure pump configured for conveying the liquid fuel to at least the liquid injector; and
a switching device for selectively conveying the liquid fuel from the second high-pressure pump to the liquid injector or to the gas injector.
9. A method for operating a dual-fuel fuel injection system comprising:
conveying, during a gas operation, a liquid fuel to a gas injector assembly of the dual-fuel fuel injection system for an internal combustion engine, the dual-fuel fuel injection system comprising:
a liquid fuel injection branch;
a liquid injector assembly, fluidically connected to the liquid fuel injection branch;
a gas fuel injection branch;
the gas injector comprising a control valve fluidically connected to the liquid fuel injection branch, wherein the gas injector is arranged in the gas fuel injection branch and the control valve is controllable by a control fluid to control gas flow provided by the gas fuel injection branch, wherein the control fluid comprises the liquid fuel provided by the liquid fuel injection branch;
a first high-pressure pump configured for conveying the liquid fuel to the gas injector;
a second high-pressure pump configured for conveying the liquid fuel to the liquid injector; and
a switching device for selectively conveying the liquid fuel to the liquid injector or to the gas injector; and
conveying, by a first high-pressure pump and during the gas operation, the liquid fuel to the liquid injector;
conveying, by a second high-pressure pump and during the gas operation, the liquid fuel to the switching device
selectively conveying, by the switching device, the liquid fuel from the second high-pressure pump to the liquid injector; and
selectively conveying, by the switching device, the liquid fuel from the second high-pressure pump to the gas injector.
10. The method of claim 9 , further comprising selectively conveying, by the first high-pressure pump, the liquid fuel to the liquid injector or to the gas injector.