Low pressure fuel and air charge forming device for a combustion engine
In at least some implementations, a throttle body assembly for a combustion engine includes a throttle body having a pressure chamber in which a supply of fuel is received and a throttle bore with an inlet through which air is received, a throttle valve carried by the throttle body with a valve head movable relative to the throttle bore to control fluid flow through the throttle bore, and a metering valve carried by the throttle body. The metering valve may have a valve element that is movable between an open position wherein fuel may flow from the pressure chamber into the throttle bore and a closed position where fuel is prevented or substantially prevented from flowing into the throttle bore through the metering valve.
1. A throttle body assembly for a combustion engine, comprising:
a throttle body having a pressure chamber in which a supply of liquid fuel is received through a fuel inlet and an outlet, and a throttle bore with an inlet through which air is received;
a throttle valve carried by the throttle body with a valve head movable relative to the throttle bore to control fluid flow through the throttle bore;
a metering valve carried by the throttle body and having an electrically driven actuator, a valve element that is movable by the electrically driven actuator between an open position wherein fuel may flow from the pressure chamber outlet into the throttle bore and a closed position where less fuel flows through the metering valve and into the throttle bore as compared to when the valve element is in the open position, and wherein less fuel includes the condition in which no fuel flows through the metering valve; and
a valve assembly including a valve that is movable relative to a valve seat to control fuel flow into the pressure chamber through the fuel inlet, and a float coupled to the valve to move the valve to a closed position against the valve seat when a threshold level of fuel exists in the pressure chamber.
2. The assembly of claim 1 wherein a boost venturi is provided within the throttle bore so that some of the air that flows through the throttle bore flows through the boost venturi and some of the air that flows through the throttle bore flows around the boost venturi, and wherein fuel flows into the boost venturi when the metering valve is open.
3. The assembly of claim 1 which also comprises a second metering valve and wherein one metering valve provides fuel flow into the throttle bore at a threshold fuel flow rate or below and the other metering valve enables fuel flow into the throttle bore at fuel flow rates above the threshold.
4. The assembly of claim 1 wherein the pressure chamber is at or within 10% of atmospheric pressure when the engine is operating.
5. The assembly of claim 1 wherein the pressure chamber is at a superatmospheric pressure of 6 psi or less when the engine is operating.
6. The assembly of claim 1 wherein the throttle valve includes a throttle valve shaft that is driven for rotation by an electrically powered actuator and wherein a throttle position sensor is carried at least in part by the shaft for rotation with the shaft.
7. The assembly of claim 6 which also includes a control module that has a circuit board including a controller that controls the actuator, and wherein at least one of a drive shaft of the actuator or the throttle valve shaft or a coupler between the drive shaft and throttle valve shaft extends through the circuit board.
8. The assembly of claim 7 wherein the actuator is mounted to or carried by the control module.
9. The assembly of claim 6 which includes a coupler between a drive shaft of the actuator and the throttle valve shaft to transmit rotary motion from the drive shaft to the throttle valve shaft, and wherein the coupler frictionally engages the throttle body.
10. The assembly of claim 7 which also comprises a pressure sensor carried by the module and having an output communicated with the controller.
11. The assembly of claim 1 which also includes a control module that has a housing and a circuit board including a controller, and wherein the metering valve is electrically actuated and controlled at least in part by the controller, and wherein the circuit board and metering valve are carried by the housing.
12. The assembly of claim 11 wherein the throttle valve includes a throttle valve shaft that is driven for rotation by an electrically powered actuator and wherein the actuator is carried by the housing and controlled at least in part by the controller.
13. The assembly of claim 11 wherein the metering valve includes a body that is rotated by the actuator to move the metering valve body relative to a valve seat.
14. The assembly of claim 1 which also includes a fuel pump carried by the throttle body and providing an output of fuel at greater than atmospheric pressure to the throttle bore.
15. The assembly of claim 14 which includes a fuel inlet and an inlet chamber in the throttle body, and an inlet valve having a float that is responsive to a level of fuel in the inlet chamber so that the float moves the inlet valve to a closed position when a threshold level of fuel exists in the fuel chamber to prevent excess fuel from being forced into the throttle body through the fuel inlet.
16. The assembly of claim 1 wherein the throttle body also includes a vent communicating with the pressure chamber and through which gaseous matter in the pressure chamber may exit the pressure chamber.
17. A throttle body assembly for a combustion engine, comprising:
a throttle body having a pressure chamber in which a supply of liquid fuel is received, and a throttle bore with an inlet through which air is received;
a throttle valve carried by the throttle body with a valve head movable relative to the throttle bore to control fluid flow through the throttle bore;
a control module having a housing carried by the throttle body and having a circuit board and a controller carried by the housing; and
an actuator coupled to the throttle valve to move the throttle valve between a first position and a second position, the actuator being carried by the housing and being controlled at least in part by the controller.
18. The assembly of claim 17 which also includes a metering valve carried by the throttle body and having a valve element that is movable between an open position wherein fuel may flow from the pressure chamber into the throttle bore and a closed position where less fuel-flows into the throttle bore through the metering valve as compared to when the valve element is in the open position, and wherein less fuel includes the condition in which no fuel flows through the metering valve, and wherein the metering valve is electrically actuated and controlled at least in part by the controller.
19. The assembly of claim 18 wherein the metering valve is directly coupled to the housing.
20. The assembly of claim 19 wherein the metering valve is carried at least in part by the housing.