Fuel and air charge forming device
A charge forming device for a combustion engine includes a throttle body having a throttle bore, an air passage having at least a portion in which air flows separate from the throttle bore and a throttle valve with a valve head movable relative to the throttle body. A nozzle body has a fuel passage and a feed passage, the fuel passage is arranged to receive fuel that exits a fuel outlet of a fuel metering valve, and the fuel passage is communicated with a fuel chamber through which fluid flows into the throttle bore, and the feed passage is communicated with the air passage to receive air from the air passage and the feed passage is communicated with the fuel passage upstream of the fuel chamber, wherein air in the feed passage is mixed with fuel in the fuel passage upstream of the fuel chamber.
1. A charge forming device for a combustion engine, comprising:
a throttle body having a throttle bore with an inlet through which air flows into the throttle bore, an outlet from which a fuel and air mixture exits the throttle bore, and an air passage having at least a portion in which air flows separate from the throttle bore;
a throttle valve having a valve head received within the throttle bore and movable relative to the throttle body between a first position and a second position wherein the flow area between the valve head and the throttle body is greater when the valve head is in the second position than in the first position;
a fuel metering valve having a valve element and a fuel outlet, the valve element is movable relative to a valve seat to control fuel flow through the fuel outlet; and
a nozzle body having a fuel passage and a feed passage, the fuel passage is arranged to receive fuel that exits the fuel outlet, and the fuel passage is communicated with a fuel chamber through which fluid flows into the throttle bore, and the feed passage is communicated with the air passage to receive air from the air passage and the feed passage is communicated with the fuel passage upstream of the fuel chamber, wherein air in the feed passage is mixed with fuel in the fuel passage upstream of the fuel chamber.
2. The device of claim 1 , wherein the nozzle body is at least partially received within a cavity in the throttle body, and the fuel chamber is defined between an end of the nozzle body and a surface of the throttle body that defines part of the cavity.
3. The device of claim 2 , wherein the nozzle body includes a nozzle body outlet through which a mixture of fuel and air flows into the fuel chamber, and wherein a distance between the end of the nozzle body and the surface that defines the cavity is equal to or less than a diameter of the nozzle body outlet.
4. The device of claim 2 , wherein the nozzle body includes a nozzle body outlet through which a mixture of fuel and air flows into the fuel chamber, and wherein a flow area of the nozzle body outlet is between 15% and 45% of the volume of the fuel chamber.
5. The device of claim 2 , wherein the surface of the throttle body that defines part of the cavity is part of a wall, and wherein the wall includes fuel outlets through which fuel flows into the throttle bore.
6. The device of claim 1 , wherein one or both of the air passage and the feed passage includes a reduced diameter portion that is upstream of where the feed passage is communicated with the fuel passage.
7. The device of claim 6 , further comprising a jet provided in the air passage or in the feed passage, the jet defining a minimum air flow area of both the air passage and the feed passage.
8. The device of claim 1 , wherein the feed passage intersects the fuel passage within the nozzle body.
9. The device of claim 8 , wherein the feed passage includes an inlet that has a flow area that is larger than a portion of the feed passage downstream from the inlet to increase air velocity from the inlet to said portion of the feed passage downstream from the inlet.
10. The device of claim 1 , wherein the fuel passage includes a first portion and a second portion, the first portion has a smaller flow area than the second portion to change the velocity and pressure of fuel flowing through the fuel passage.
11. The device of claim 10 , wherein the feed passage intersects the fuel passage within the second portion, and wherein the first portion is upstream of the second portion relative to the direction of fuel flow through the fuel passage.
12. A charge forming device for a combustion engine, comprising:
a throttle body having a throttle bore with an inlet through which air flows into the throttle bore, an outlet from which a fuel and air mixture exits the throttle bore, and an air passage having at least a portion in which air flows separate from the throttle bore;
a throttle valve having a valve head movable relative to the throttle body between a first position and a second position wherein the flow area between the valve head and the throttle body is greater when the valve head is in the second position than in the first position; and
a nozzle body having a fuel passage and a feed passage, the fuel passage is arranged to receive fuel prior to that fuel entering the throttle bore, and the nozzle body includes a nozzle body outlet that is communicated with a fuel chamber defined between the nozzle body and the throttle body and through which fluid flows into the throttle bore, and the feed passage is communicated with the air passage to receive air from the air passage and the feed passage is communicated with the fuel passage upstream of the fuel chamber, wherein air in the feed passage is mixed with fuel in the fuel passage upstream of the fuel chamber.
13. The device of claim 12 , wherein the nozzle body is received within a cavity in the throttle body, and the fuel chamber is defined between an end of the nozzle body and a surface that defines part of the cavity.
14. The device of claim 13 , wherein a distance between the end of the nozzle body and the surface that defines the cavity is equal to or less than a diameter of the nozzle body outlet.
15. The device of claim 13 , wherein a flow area of the nozzle body outlet is between 15% and 45% of the volume of the fuel chamber.
16. The device of claim 13 , wherein the feed passage intersects the fuel passage within the nozzle body.
17. The device of claim 16 , wherein the feed passage has a first portion with a smaller flow area than a second portion upstream of the first portion with respect to the direction of air flow through the feed passage, and the first portion is upstream of the intersection with the fuel passage.
18. The device of claim 16 , wherein the fuel passage includes a first portion with a larger flow area than a second portion of the fuel passage, the first portion is downstream of the second portion with respect to the direction of fuel flow in the fuel passage, and the feed passage intersects the fuel passage in said first portion of the fuel passage.
19. The device of claim 12 , wherein one or both of the air passage and the feed passage includes a reduced diameter portion that is upstream of where the feed passage is communicated with the fuel passage.
20. The device of claim 19 , further comprising a jet provided in the air passage or in the feed passage, the jet defining a minimum air flow area of both the air passage and the feed passage.