Fuel injection systems

Claim 2

A fuel injection system for an internal combustion engine, including a. a fuel flow path (1, 2, 63, 80A, 62, 61), b. at least one fuel injector device (83) connected to receive fuel from the flow path, c. a fuel metering device (80) connected in the flow path and operable to vary fuel flow to said one injector device, d. an air valve (4) located in the engine air supply path (3) to produce a control pressure differential over a portion of the air supply path, and e. a servomechanism operable to adjust the air valve to maintain said control pressure differential substantially constant at a single predetermined value under all engine operating conditions, said servomechanism comprising i. an air pressure control circuit (18A, 18, 17, 15), ii. air pressure responsive means (8) exposed to the pressure in the control circuit and connected to the air valve to adjust the air valve in response to variation in the air pressure in the control circuit, and iii. a signal valve mechanism (24, 25, 21) including signal valve means (21) connected in the control circuit, the signal valve mechanism being exposed to the control pressure differential in the said portion of the air supply path and connected to operate said signal valve means (21) in response to any variation in said control pressure differential from a predetermined value to produce a variation in the air pressure in the control circuit (17) and thereby adjust the air valve to return said control pressure differential to the said predetermined value under all engine operating conditions, the fuel metering device (80) being coupled to the air valve for adjustment in response to adjustment of the air valve.

Claim 3

A system as claimed in claim 1, including a fuel pressurizing device connected in the flow path and operable, in response to adjustment of the air valve, to vary the pressure at which fuel flows to said at least one injector device.

Claim 4

A system as claimed in claim 1, in which the air valve is located in the engine air supply path upstream of the throttle valve to produce the control pressure differential between the air valve and the throttle valve. 4, A system as claimed in claim 1, in which the air pressure-responsive means is exposed to the pressure in a control chamber in the air control circuit, the control chamber being coupled to a source which provides a constant vacuum throughout the engine operating range, and the signal valve means being operable to admit atmospheric air to the control circuit to produce a variation in the air pressure in the control chamber to adjust the air valve.

Claim 5

A system as claimed in claim 4, including a mixture valve operable to admit atmospheric air to the control chamber to adjust the air vaLve independently of the signal valve mechanism.

Claim 6

A system as claimed in claim 5, in which the mixture valve is operable to adjust the air supply to the engine simultaneously with adjustment of the air valve.

Claim 7

A system as claimed in claim 5, in which the mixture valve is responsive to a selected temperature.

Claim 8

A system as claimed in claim 1, including at least two fuel injector devices each connected to receive fuel from the fuel flow path, and having respective fuel pressure responsive injector control valves each exposed to fuel pressure in the flow path and operable to permit fuel flow to the associated injector device, and respective control devices operable independently of each other in response to an engine operating parameter to adjust the associated injector control valve from an inoperative state in which a predetermined fuel pressure in the flow path is insufficient to operate the injector control valve to an operative state in which the said predetermined fuel pressure in the flow path is sufficient to operate the injector control valve.

Claim 9

A system as claimed in claim 1, in which the fuel metering device includes a variable metering orifice which is connected in the fuel flow path to supply fuel to said at least one injector device and the area of which is adjustable in response to adjustment of the air valve.

Claim 10

A system as claimed in claim 1, in which the fuel metering device includes a variable metering orifice which is connected in the fuel flow path to by-pass fuel from said at least one injector device and the area of which is adjustable in response to adjustment of the air valve.

Claim 11

A system as claimed in claim 1, in which the fuel metering device includes an elongated valve member located within and axially movable relative to a sleeve member, one of the said members including a groove which extends in the axial direction and the cross-sectional area of which varies in that direction, the groove cooperating with a portion of the other of the said members to define a metering orifice the area of which is variable by relative axial movement between the valve member and the sleeve member.

Claim 12

A system as claimed in claim 1, which is operable to discharge fuel continuously from said at least one injector device.

Claim 13

A fuel injection system for an internal combustion engine, including f. a fuel flow path (1, 2, 63, 80A, 62, 61), g. at least one fuel injector device (83) connected to receive fuel from the flow path, h. a fuel pressurizing device (100) connected in the flow path and operable to vary the pressure at which fuel flows to said at least one injector device, j. an air valve (4) located in the engine air supply path (3) to produce a control pressure differential over a portion of the air supply path, and k. a servomechanism operable to adjust the air valve to maintain said control pressure differential substantially constant at a single predetermined value under all engine operating conditions, said servomechanism comprising iv. an air pressure control circuit (18A, 18, 17, 15), v. air pressure responsive means (8) exposed to the pressure in the control circuit and connected to the air valve to adjust the air valve in response to variation in the air pressure in the control circuit, and vi. a signal valve mechanism (24, 25, 21) including signal valve means (21) connected in the control circuit, the signal valve mechanism being exposed to the control pressure differential in the said portion of the air supply path and connected to operate said signal valve means (21) in response to any variation in the control pressure differential from a predetermined value to produce a variation in the air pressure in the control circuit (17) and thereby adjust the air valve to return said control pressure differential to the said predetermined value under all engine operating conditions, the fuel pressurizing device (100) being responsive to a pressure which varies with the position of the air valve wHereby the pressurizing device operates in response to adjustment of the air valve.

Claim 14

A fuel injection system for an internal combustion engine, including f. a fuel flow path (1, 2, 63, 80A, 62, 61), g. at least one fuel injector device (83) connected to receive fuel from the flow path, h. a fuel pressurizing device (100) connected in the flow path and operable to vary the pressure at which fuel flows to said at least one injector device, j. an air valve (4) located in the engine air supply path (3) to produce a control pressure differential over a portion of the air supply path, and k. a servomechanism operable to adjust the air valve to maintain said control pressure differential substantially constant at a single predetermined value under all engine operating conditions, said servomechanism comprising iv. an air pressure control circuit (18A, 18, 17, 15), v. air pressure responsive means (8) exposed to the pressure in the control circuit and connected to the air valve to adjust the air valve in response to variation in the air pressure in the control circuit, and vi. a signal valve mechanism (24, 25, 21) including signal valve means (21) connected in the control circuit, the signal valve mechanism being exposed to the control pressure differential in the said portion of the air supply path and connected to operate said signal valve means (21) in response to any variation in the control pressure differential from a predetermined value to produce a variation in the air pressure in the control circuit (17) and thereby adjust the air valve to return said control pressure differential to the said predetermined value under all engine operating conditions, the fuel pressurizing device (100) being responsive to a pressure which varies with the position of the air valve wHereby the pressurizing device operates in response to adjustment of the air valve.

Claim 15

A system as claimed in claim 13, including means operable to supply fuel to the fuel flow path in excess of the engine operating requirements, the pressurizing device being operable to by-pass fuel from the flow path in dependence on the adjustment of the air valve.

Claim 16

A system as claimed in claim 13, in which the air valve is located in the engine air supply path upstream of the throttle valve to produce the control pressure differential between the air valve and the throttle valve.

Claim 17

A system as claimed in claim 13, in which the fuel pressurizing device communicates through a conduit with a slot which extends along the engine air supply path in the region of the control pressure differential and adjacent the air valve whereby the length of the slot exposed to the control pressure differential is dependent on the adjustment of the air valve.

Claim 18

A system as claimed in claim 13, in which the fuel pressurizing device communicates with the control pressure differential region of the engine air supply path through a conduit which is vented to atmosphere through a variable restrictor which is adjustable by operation of the signal valve mechanism.

Claim 19

A system as claimed in claim 14, including means operable to maintain a substantially constant pressure in the fuel by-pass path of the pressurizing device throughout the engine operating range, which substantially constant pressure is sufficient to prevent fuel vaporization.

Claim 20

A system as claimed in claim 18, in which the fuel flow path is connected to said at least one injector device through a distributor unit including a pressure-responsive member biased, by a resilient member and fuel at the said substantially constant pressure, to a closed position to prevent fuel flow to said at least one injector device and movable against the bias to an open position by fuel pressure in the fuel flow path.

Claim 21

A system as claimed in claim 16, including a fuel pressure adjustment mechanism operable to admit atmospheric air to the conduit connecting the fuel pressurizing device to the control pressure differential region to operate the pressurizing device independently of the air valve.

Claim 22

A system as claimed in claim 20, in which the fuel pressure adjustment mechanism is responsive to engine air intake and operable in response to an engine air intake of a predetermined value.

Claim 23

A system as claimed in claim 21, in which the fuel pressure adjustment mechanism communicates with the engine air supply path downstream of the throttle valve.

Claim 24

A system as claimed in claim 13 including at least two fuel injector devices each connected to receive fuel from the fuel flow path, and having respective fuel pressure responsive injector control valves each exposed to fuel pressure in the flow path and operable to permit fuel flow to the associated injector device, and respective control devices operable independently of each other in response to an engine operating parameter to adjust the associated injector control valve from an inoperative state in which a predetermined fuel pressure in the flow path is insufficient to operate the injector control valve to an operative state in which the said predetermined fuel pressure in the flow path is sufficient to operate the injector control valve.

Claim 25

A system as claimed in claim 13, which is operable to discharge fuel continuously from said at least one injector device.

Claim 26

A valve as claimed in claim 1, in which the groove has a V-shaped cross-section, the depth of the groove varying in the axial direction.

Claim 27

A valve as claimed in claim 25, in which the groove is formed in the valve member.

Claim 28

A valve as claimed in claim 25, in which the sleeve member is an open-ended tubular member and the metering orifice is defined in a fluid flow path between the open end of the tubular member and an aperture in the wall of the tubular member.

Claim 29

A system as claimed in claim 13, in which the air pressure-responsive means is exposed to the pressure in a control chamber in the air control circuit, the control chamber being coupled to a source which provides a constant vacuum throughout the engine operating range, and the signal valve means being operable to admit atmospheric air to the control circuit to produce a variation in the air pressure in the control chamber to adjust the air valve.