Fuel injection pumping apparatus

Claim 2

A fuel injection pumping apparatus for supplying fuel to internal combustion engines and comprising an accumulator in which fuel is stored at high pressure, a cylinder, a displacement piston contained within said cylinder, an outlet communicating with one end of said cylinder, valve means for controlling flow of fuel from a low pressure source to said one end of the cylinder, a first valve positioned intermediate the accumulator and the other end of said cylinder and operable to allow fuel under pressure from the accumulator to act on one end of said displacement piston thereby to cause movement of said piston to displace fuel through said outlet, a second valve through which said other end of the cyliNder can be connected to a drain, actuating means for actuating said first and second valves whereby said displacement piston is moved to said one end of the cylinder to displace fuel through the outlet by opening the first valve and closing the second valve, said piston being moved away from said one end of the cylinder by closing the first valve and opening the second valve, sensing means for sensing the extent of movement of the displacement piston away from said one end of the cylinder, and control means responsive to the signal produced by said sensing means for operating said actuating means to reclose said second valve to halt the movement of the displacement piston away from said one end of the cylinder.

Claim 3

An apparatus as claimed in claim 1 in which said outlet defines a spray orifice through which fuel flows into a combustion space of the associated engine.

Claim 4

An apparatus as claimed in claim 1 including an injection valve for controlling the flow of fuel through a spray orifice, said injection valve being mounted within a cylinder and having a narrower end shaped for co-operation with a seating, the narrower end of the injection valve defining with the cylinder in which it is mounted a chamber communicating with said outlet, the wider end of the injection valve communicating with a source of fluid at a pressure lower than the accumulator pressure whereby when said first and second valves are operated the fuel under pressure delivered through said outlet will lift the valve member from its seating to allow flow of fuel through said spray orifice.

Claim 5

An apparatus as claimed in claim 3 including a push member disposed between the displacement piston and said injection valve whereby the injection valve is urged into contact with the seating to terminate the flow of fuel through the spray orifice at a predetermined position of the displacement piston.

Claim 6

An apparatus as claimed in claim 4 in which said valve means is responsive to the accumulator pressure applied to said displacement piston, said valve means being closed when accumulator pressure is applied to the displacement piston.

Claim 7

An apparatus according to claim 5 in which said actuating means comprises a piezo-electric stack of crystals.

Claim 8

An apparatus as claimed in claim 6 in which said first and second valves are operated mechanically by the stack of crystals.

Claim 9

An apparatus as claimed in claim 6 in which said first and second valves are operated by fluid pressure, said fluid pressure being generated by a piston operated by the stack of crystals.

Claim 10

An apparatus according to claim 8 in which said control means comprises an electronic control circuit.

Claim 11

An apparatus according to claim 9 in which said sensing means comprises a sensing coil, said sensing coil being positioned about the path of movement of the displacement piston.

Claim 12

An apparatus as claimed in claim 10 in which said valve members forming said first and second valves are disposed in end to end relationship.

Claim 13

An apparatus as claimed in claim 11 in which the valve member constituting said first valve is pressure balanced.

Claim 14

An apparatus according to claim 2 in which said actuating means comprises a piezo-electric stack of crystals.

Claim 15

A fuel injection pumping apparatus for supplying fuel to internal combustion engines and comprising an accumulator in which fuel is stored at high pressure, a cylinder, a displacement piston contained within said cylinder, an outlet communicating with one end of said cylinder, valve means for controlling the flow of fuel from a low pressure source to said one end of the cylinder, a first valve positioned intermediate the accumulator and the other end of said cylinder and operable to allow fuel under pressure from the accumulator to act on one end of said displacement piston thereby to cause movement of said piston to displace fuel through said outlet, a second valve through which said other end of the cylinder can be connected to a drain, actuating means for actuAting said first and second valves whereby said displacement piston is moved to said one end of the cylinder to displace fuel through the outlet by opening the first valve and closing the second valve, said piston being moved away from said one end of the cylinder by closing the first valve and opening the second valve, a sensing coil positioned about the path of movement of the displacement piston, said sensing coil providing a signal indicative of the extent of movement of the displacement piston away from said one end of the cylinder and a control circuit responsive to the signal produced by said sensing coil for operating said actuating means to reclose said second valve thereby to halt the movement of the displacement piston away from said one end of the cylinder.

Claim 16

A fuel injection pumping apparatus for supplying fuel to internal combustion engines and comprising an accumulator in which fuel is stored at high pressure, a cylinder, a displacement piston contained within said cylinder, an outlet communicating with one end of said cylinder, valve means for controlling the flow of fuel from a low pressure source to said one end of the cylinder, a first valve positioned intermediate the accumulator and the other end of said cylinder and operable to allow fuel under pressure from the accumulator to act on one end of said displacement piston thereby to cause movement of said piston to displace fuel through said outlet, a second valve through which said other end of the cylinder can be connected to a drain, actuating means for actuAting said first and second valves whereby said displacement piston is moved to said one end of the cylinder to displace fuel through the outlet by opening the first valve and closing the second valve, said piston being moved away from said one end of the cylinder by closing the first valve and opening the second valve, a sensing coil positioned about the path of movement of the displacement piston, said sensing coil providing a signal indicative of the extent of movement of the displacement piston away from said one end of the cylinder and a control circuit responsive to the signal produced by said sensing coil for operating said actuating means to reclose said second valve thereby to halt the movement of the displacement piston away from said one end of the cylinder.

Claim 17

A fuel injection pumping apparatus for supplying fuel to internal combustion engines and comprising an accumulator in which fuel is stored at high pressure, a cylinder, a displacement piston contained within said cylinder, an outlet communicating with one end of said cylinder, valve means for controlling flow of fuel from a low pressure source to said one end of the cylinder, a first valve including a first slidable valve member, said first valve being positioned intermediate the accumulator and the other end of said cylinder and operable to allow fuel under pressure from the accumulator to act on one end of said displacement piston thereby to cause movement of said piston to displace fuel through said outlet, a second valve including a second valve member through which said other end of the cyliner can be connected to a drain, actuating means for actuating said first and second valve members whereby said displacement piston is moved to said one end of the cylinder to displace fuel through the outlet by opening the first valve and closing the second valve, said piston being moved away from said one end of the cylinder by closing the first valve and opening the second valve, sensing means for sensing the extent of movement of the displacement piston away from said one end of the cylinder, and control means responsive to the signal produced by said sensing means for operating said actuating means to reclose said second valve to halt the movement of the displacement piston away from said one end of the cylinder, said first and second valve members being disposed in end to end relationship, said second valve member being operated directly by said actuating means.

Claim 18

A fuel injection pumping apparatus for supplying fuel to internal combustion engines and comprising an accumulator in which fuel is stored at high pressure, a cylinder, a displacement piston contained within said cylinder, an outlet communicating with one end of said cylinder, valve means for controlling flow of fuel from a low pressure source to said one end of the cylinder, a first valve including a first slidable valve member, said first valve being positioned intermediate the accumulator and the other end of said cylinder and operable to allow fuel under pressure from the accumulator to act on one end of said displacement piston thereby to cause movement of said piston to displace fuel through said outlet, a second valve including a second valve member through which said other end of the cyliner can be connected to a drain, actuating means for actuating said first and second valve members whereby said displacement piston is moved to said one end of the cylinder to displace fuel through the outlet by opening the first valve and closing the second valve, said piston being moved away from said one end of the cylinder by closing the first valve and opening the second valve, sensing means for sensing the extent of movement of the displacement piston away from said one end of the cylinder, and control means responsive to the signal produced by said sensing means for operating said actuating means to reclose said second valve to halt the movement of the displacement piston away from said one end of the cylinder, said first and second valve members being disposed in end to end relationship, said second valve member being operated directly by said actuating means.

Claim 19

An apparatus as claimed in claim 15 in which said first valve member is pressure balanced.