GB1591508A

GB1591508A - Fuel injection nozzle units for direct injection internal combustion engines

Info

Publication number: GB1591508A
Application number: GB4288276A
Authority: GB
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1976-10-15
Filing date: 1976-10-15
Publication date: 1981-06-24
Also published as: ES463249A1; FR2367926A1; FR2367926B1

Description

(54) FUEL INJECTION NOZZLE UNITS FOR DIRECT INJECTION INTERNAL COMBUSTION ENGINES (71) We, LUCAS INDUSTRIES LIMITED, a British Company, of Great King Street, Birmingham B19 2XF, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:: This invention relates to fuel injection nozzle units for supplying fuel directly to a combustion space of an internal combustion engine, the nozzle unit comprising a valve member movable within a bore, a seating in the bore, the valve member being shaped for co-operation with the seating to control fuel flow through an outlet orifice, resilient means acting to urge the valve member into contact with the seating and a surface defined on the valve member and against which fuel under pressure can act to lift the valve member from the seating.

The object of the invention is to provide a nozzle unit of the kind specified in a form in which it can provide a voltage which can be used to initiate or assist the initiation of the combustion of the fuel within the combustion space of the engine.

According to the invention a nozzle unit of the kind specified comprises a piezoelectric crystal generator mounted in a body part of the nozzle unit, said generator being positioned so as to be subjected to impact directly by the valve member or indirectly by a member moved by the valve member, as the valve member is moved away from the seating.

One example of a fuel injection nozzle unit in accordance with the invention will now be described with reference to the accompanying drawing which shows the nozzle unit in sectional side elevation.

Referring to the drawing the nozzle unit comprises a body part 10 which is of elongated form and which has a lateral portion defining a fuel inlet 11 which in use is connected to a fuel injection pump. Secured to the body part 10 is a nozzle head 12, this being retained relative to the body part by means of a cap nut 13. A portion of the nozzle head extends through an aperture in the base wall of the cap nut.

Formed within the nozzle head is a longitudinally extending bore 14. At the end of the bore 14 remote from the body part 10 there is defined a seating 15 with which can co-operate the shaped end of a valve member 16 which is axially movable within the bore 14. The valve member co-operates with the seating to control the flow of fuel through outlets 17 which extend from a space defined in the nozzle head on the remote side of the seating 15 from the body part 10.

The valve member 16 is of stepped form having an intermediate portion which defines with the wall of the bore 14, an annular space which communicates with a circumferential groove 18 formed in the wall of the bore 14 intermediate the ends thereof. The groove 18 communicates by way of passages within the nozzle head and the body part 10, with the fuel inlet 11.

The valve member 16 is provided with an extension 19 at its end remote from the seating and the extension extends with clearance through an aperture formed in a stop plate 20 which is positioned between the nozzle head and the body part. The extension 19 mounts a spring abutment 21 against which bears one end of a coiled compression spring 22. The compression spring 22 is housed within a chamber 23 defined in the body part 10 and the other end of the spring 22 bears against an end wall of the chamber.

The chamber 23 is vented to a low pressure by means of a passage 24 which communicates with a further chamber 25, this latter chamber being connected to a vent 26 formed in an end closure for the chamber 25.

In operation, when fuel under pressure is supplied to the inlet 11 the pressure acts upon surfaces defined on the valve member to lift the valve member from the seating and thereby allow fuel flow through the orifices 17. The extent of movement of the valve member is limited by its abutment with the stop plate 20. When the flow of fuel through the inlet ceases then the valve member is returned into contact with its sea ting by the action of the spring 22.

The particular nozzle unit described is for supplying fuel to the combustion space of a compression ignition engine where the initiation of combustion of the fuel is effected by the very high temperature which is imparted to the air within the combustion space of the engine prior to injection of the fuel. In some instances however it is desirable to assist the initiation of the combustion of fuel and one way in which this can be done is to provide a sparking plug having its electrodes exposed within the combustion space. A high voltage supply is required for the sparking plug and this is conveniently obtained as will be described, from a piezo-electric crystal generator which is associated with the nozzle unit.

Referring again to the drawing the generator is shown at 27 and comprises a stack of piezo-electric crystal discs 28. These are housed within an extension of the chamber 25 and are located against an insulating washer 29 which in turn is located against the end closure of the chamber. At the other end of the stack a further insulating washer 30 is provided and this is engaged by a coiled compression spring 31 which is located within a recess formed in a piston like impact member 32. The member 32 is slidable within the chamber 25 and has an extension rod 33 which in the rest position engages the abutment 21. The crystal generator is provided with an output lead which extends through an aperture in the end closure. The conductor is insulated from the wall of the aperture and the other terminal of the generator is connected to the body part of the nozzle.In use, the conductor is connected to the central electrode of a sparking plug which is shown at 34 and the outer electrode of the sparking plug is connected to earth. In operation, when the valve member 16 is lifted by the fuel under pressure it effects movement of the member 32 which has appreciable inertia. As previously mentioned the movement of the valve member 16 is halted by the stop plate 20 but the member 32 can continue to move due to its inertia, against the action of the spring 31. The movement of the member is halted by its impact with the washer 30 and this impact causes deformation of the stack of discs 28. A high voltage is produced by the generator and a spark occurs at the electrodes of the sparking plug 34.It will be appreciated that the spark occurs a short time after the commencement of fuel flow to the combustion chamber and this spark can initiate or assist the initiation of combustion of the fuel. The return motion of the member 32 is effected by the coiled compression spring 31.

In the example described above the member 32 due to its inertia, restricts the rate at which the valve member 16 can open. This is useful in certain types of compression ignition engine because it means that the initial rate of fuel flow to the combustion chamber is restricted.

In an alternative construction the valve member 16 has a longer extension so that it can act directly upon the generator and in this instance there is substantially no restricted of the initial rate of fuel flow to the engine. Moreover, the generator also acts to limit the extent of movement of the valve member so that the stop plate 20 is no longer required.

With the apparatus as described the spark will occur each time fuel is delivered to the engine. This in itself may be undesirable in which case means may be provided to prevent a spark occurring at the electrodes of the sparking plug. This can be achieved by a switch operable to short the electrodes of the plug.

WHAT WE CLAIM IS: 1. A fuel injection nozzle unit for supplying fuel directly to a combustion space of an internal combustion engine, the nozzle unit comprising a valve member movable within a bore, a seating in the bore, the valve member being shaped for cooperation with the seating to control fuel flow through an outlet orifice, resilient means acting to urge the valve member into contact with the seating, a surface defined on the valve member and against which fuel under pressure can act to lift the valve member from the seating, and a piezoelectric crystal generator mounted in a body part of the nozzle unit, said generator being positioned so as to be subject to impact directly by the valve member or indirectly by an impact member moved by the valve member as the valve member is moved away from the seating.

2. A nozzle unit according to Claim 1 in which said generator comprises a stack of piezo-electric crystals located within a chamber defined in said body part.

3. A nozzle unit according to Claim 2 in which said impact member is slidable in said chamber, the impact member mounting an extension engageable with a part carried by the valve member, whereby as the valve member is moved away from the seating movement will be imparted to said impact member, and further resilient means for biasing said impact member in a direction towards said seating.

4. A nozzle unit according to Claim 3 in which said part forms an abutment for a coiled compression spring which constitutes the first-mentioned resilient means, said extension extending within said spring.

5. A nozzle unit according to Claim 4 in which said impact member is engageable with an insulating washer disposed adjacent

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ting by the action of the spring 22. The particular nozzle unit described is for supplying fuel to the combustion space of a compression ignition engine where the initiation of combustion of the fuel is effected by the very high temperature which is imparted to the air within the combustion space of the engine prior to injection of the fuel. In some instances however it is desirable to assist the initiation of the combustion of fuel and one way in which this can be done is to provide a sparking plug having its electrodes exposed within the combustion space. A high voltage supply is required for the sparking plug and this is conveniently obtained as will be described, from a piezo-electric crystal generator which is associated with the nozzle unit. Referring again to the drawing the generator is shown at 27 and comprises a stack of piezo-electric crystal discs 28. These are housed within an extension of the chamber 25 and are located against an insulating washer 29 which in turn is located against the end closure of the chamber. At the other end of the stack a further insulating washer 30 is provided and this is engaged by a coiled compression spring 31 which is located within a recess formed in a piston like impact member 32. The member 32 is slidable within the chamber 25 and has an extension rod 33 which in the rest position engages the abutment 21. The crystal generator is provided with an output lead which extends through an aperture in the end closure. The conductor is insulated from the wall of the aperture and the other terminal of the generator is connected to the body part of the nozzle.In use, the conductor is connected to the central electrode of a sparking plug which is shown at 34 and the outer electrode of the sparking plug is connected to earth. In operation, when the valve member 16 is lifted by the fuel under pressure it effects movement of the member 32 which has appreciable inertia. As previously mentioned the movement of the valve member 16 is halted by the stop plate 20 but the member 32 can continue to move due to its inertia, against the action of the spring 31. The movement of the member is halted by its impact with the washer 30 and this impact causes deformation of the stack of discs 28. A high voltage is produced by the generator and a spark occurs at the electrodes of the sparking plug 34.It will be appreciated that the spark occurs a short time after the commencement of fuel flow to the combustion chamber and this spark can initiate or assist the initiation of combustion of the fuel. The return motion of the member 32 is effected by the coiled compression spring 31. In the example described above the member 32 due to its inertia, restricts the rate at which the valve member 16 can open. This is useful in certain types of compression ignition engine because it means that the initial rate of fuel flow to the combustion chamber is restricted. In an alternative construction the valve member 16 has a longer extension so that it can act directly upon the generator and in this instance there is substantially no restricted of the initial rate of fuel flow to the engine. Moreover, the generator also acts to limit the extent of movement of the valve member so that the stop plate 20 is no longer required. With the apparatus as described the spark will occur each time fuel is delivered to the engine. This in itself may be undesirable in which case means may be provided to prevent a spark occurring at the electrodes of the sparking plug. This can be achieved by a switch operable to short the electrodes of the plug. WHAT WE CLAIM IS:

1. A fuel injection nozzle unit for supplying fuel directly to a combustion space of an internal combustion engine, the nozzle unit comprising a valve member movable within a bore, a seating in the bore, the valve member being shaped for cooperation with the seating to control fuel flow through an outlet orifice, resilient means acting to urge the valve member into contact with the seating, a surface defined on the valve member and against which fuel under pressure can act to lift the valve member from the seating, and a piezoelectric crystal generator mounted in a body part of the nozzle unit, said generator being positioned so as to be subject to impact directly by the valve member or indirectly by an impact member moved by the valve member as the valve member is moved away from the seating.

one end of said stack of crystals.

6. A nozzle unit as claimed in Claim 5 in which a further insulating washer is disposed adjacent the other end of said stack of crystals said further insulating washer engaging against an end closure for the chamber.

7. A nozzle unit according to Claim 6 in which said further resilient means comprises a coiled compression spring acting between said impact member and the first-mentioned insulating washer.

8. A nozzle unit according to Claim 7 in which said impact member is formed with a recess to partly accommodate the secondmentioned spring.

9. A nozzle unit according to any one of Claims 3 to 8 including a stop plate operable to limit the movement of the valve member away from the seating.

10. A fuel injection nozzle unit for supplying fuel directly to a combustion space of an internal combustion engine comprising the combination and arrangement of parts substantially as described with reference to the accompanying drawing.