Fuel injector clamping sub-assembly

Abstract

 An injector clamping sub-assembly (10) for clamping to a cylinder head (80) of an internal combustion engine, comprising a fuel injector (11) having an injector body (12), a projecting inlet portion (18) and an outlet portion (86), and a fuel rail body (14) having a bore (20) adapted to receive the projecting inlet portion (18) and connect the inlet portion (18) within the fuel rail body (14). Two wave washers (26, 28) disposed between the injector body (12) and fuel rail body (14) urge the injector body (12) and fuel rail body (14) apart. Indexing and connecting portions (48, 50) disposed on the injector (11) correctly locate and orientate the injector (11) with the fuel rail body (14) and retain the injector (11) therein whilst allowing relative movement therebetween. The wave washers (26, 28) provide the sub-assembly (10) with a desired preload for clamping the sub-assembly (10) to a cylinder head (80). A fuel injection system comprising such an injector clamping sub-assembly (10) and a connecting part (16) for arrangement on the projecting inlet portion (18) of an injector (11) are also provided.

Description

[0001] The present invention relates generally to internal combustion engines and more specifically to a fuel injector clamping assembly for an internal combustion engine.

[0002] Internal combustion engines, particularly compression ignition internal combustion engines, typically comprise a high pressure common rail fuel injection system. These systems include a plurality of fuel injectors each typically connected at an upper inlet end to a high pressure fuel rail and having an outlet end in the cylinder head.

[0003] To prevent the injectors moving in the cylinder head when assembled therewith, each injector typically requires a pre-load. Vibration forces can cause such movement but the main force that affects movement of the injector is the force from combustion pressure when the pressure in the fuel rail is lower than the pressure in the combustion chamber of the cylinder. An amount of preload is provided to the injector by the fuel rail pressure. For example, in a Gasoline Direct Injection (GDI) system, a preload of approximately 2000 N per injector is induced at a nominal fuel rail pressure of 200 bar. In a theoretical worst case scenario of no or negligible pressure in the fuel rail and maximum combustion pressure in the cylinder, approximately 500 N per injector would be induced in the opposite direction. Therefore, 500N is a desirable value to preload the injector with.

[0004] A desired preload may be achieved by using a spring disposed between an upper part of each injector and the fuel rail, thereby to facilitate a degree of opposed movement between each injector and the fuel rail. The desired preloads for each injector are achieved by the partial compression of each spring during assembly of the fuel rail and injectors with the cylinder head.

[0005] Such compression springs may include coil, belleville and leaf springs. However, a number of disadvantages are associated with these springs. Firstly, coil springs require relatively large dimensions to achieve the desired preload forces. Belleville springs typically comprise a dome-shaped disc and have inadequate characteristics for this application. In particular, the internal diameter of a typical belleville spring is too small relative to the packaging requirements of other components, e.g. the injector, and the spring travel is insufficient to achieve the desired preload, thus requiring many springs to be arranged in series. A folded leaf spring may be adapted to form a type of spring clip to secure the injector to the fuel rail and provide compression during assembly. However, to ensure secure, centralised loading on the injector, the shape of the spring clip must be complex and the contact surfaces on the injector and fuel rail, to locate and secure the spring clip in position, require costly machining. Also, the spring clip requires a relatively large spacing between its upper and lower parts to achieve the desired preload when the two parts of the spring clip are compressed towards each other during assembly. This increases the packaging space required and is detrimental to the space available for other components, e.g. electrical connectors. Many types of spring have the disadvantage of requiring a relatively large packaging space which is undesirable and even impossible where the available space is limited.

[0006] A first aspect of the present invention provides an injector clamping sub-assembly for clamping to a cylinder head, the assembly comprising:

• a fuel injector having an elongate injector body, a projecting inlet portion having an inlet, and an outlet portion;
• a system body having a bore adapted to receive the projecting inlet portion and connect the inlet within the system body;
• one or more wave washers disposed between the injector body and the system body to urge the injector body and system body apart; and
• connecting means to locate and retain the projecting inlet portion in said bore whilst allowing relative movement between the injector body and the system body.

[0007] The projecting inlet portion of the injector body is received by the bore of the system body and is retained in the system body by the connecting means. Preferably, the projecting inlet portion is complementarily shaped with the bore to allow the projecting inlet portion to engage with and be guided by the bore when slidably inserted therein to connect the inlet within the system body. In an alternative embodiment, the system body may comprise a projecting inlet portion and the injector may comprise a complimentarily shaped bore which allows the injector to be slidably received over the projecting inlet portion of the system body.

[0008] The connecting means allow the injector to connect with the system body whilst allowing a degree of relative movement therebetween, particularly in a vertical direction substantially parallel with a longitudinal axis of the injector. The injector is therefore allowed to hang from the system body forming a sub-assembly which is easier to handle during complete assembly with a cylinder head. This allows quick and easy assembly of the system body and injector with the cylinder head and also disassembly and removal therefrom. The connection means also provide a means of locating the injector correctly within the system body, particularly the angular orientation thereof about the longitudinal axis of the injector. This is particularly convenient when attaching an electrical connection to the injector after assembly with the cylinder head, for example. Typically, an electrical connection to the injector comprises a plug and socket arrangement wherein the plug comprises a plurality of pins which suitably engage for electrical connection with the socket substantially perpendicularly disposed on a part of the injector relative to the longitudinal axis thereof. The plug and socket arrangement typically comprises attachment means, e.g. clips, to ensure the plug is securely attached in the socket. Correct orientation of the injector about its axis and positioning of the socket, for example, on the injector is particularly convenient for connecting the injector to an electrical source.

[0009] Suitably, the wave washer provides a spring force to urge the injector body and system body apart. When the system body is clamped to the cylinder head, the clamping load applied must overcome the spring force and partially compress the wave washer. The injector body and system body can move relative to each other to allow for this partial compression. The spring force therefore provides the sub-assembly with a desired preload. Conveniently, the wave washer characteristics can be chosen according to the desired preload.

[0010] The fuel injector comprises the elongate injector body, the projecting inlet portion disposed at an upper end of the injector body and the outlet portion disposed at a lower end of the injector body, when in use. The outlet portion is generally in the form of a nozzle portion. The elongate injector body is tubular in shape having a longitudinal axis and the projecting inlet portion extends from the upper end of the injector body along the longitudinal axis and has a reduced diameter to the injector body defining a circumferential shoulder.

[0011] Conveniently, available wave washers have suitable inner and outer diameters to fit around the projecting inlet portion or elongate, tubular shape of the injector body and within the packaging constraints of such an application, unlike other types of spring as described above. Suitably, the wave washer is spring steel and is conveniently a readily available component.

[0012] Preferably, the system body is a fuel rail body. Alternatively, the system body may be a clamping member. A clamping member may suitably be used for clamping a fuel rail and injector to a cylinder head. Where the system body is a clamping member or fuel rail body, a wave washer may be disposed around the projecting inlet portion and/or the outlet portion of the injector. Where a wave washer is disposed around the outlet portion of the injector, the wave washer may suitably interface with an injector bore in a cylinder head.

[0013] Preferably, a stack of wave washers is disposed between the fuel injector body and system body. Using a stack of wave washers in series suitably provides greater spring travel for the same preload force per injector, if required.

[0014] Where a stack of wave washers is used, the washers may be joined together using suitable joining techniques, for example welding or adhering. Due to the sinusoidal profile of each wave washer, the angular orientation of each wave washer relative to its neighbouring wave washer must be fixed. Neighbouring wave washers will suitably require joining together at opposing crests and troughs to ensure that the crests of a lower wave washer always interface with the troughs of an upper, neighbouring wave washer. If a stack of wave washers is not secured together, the stack will not function correctly, as will be understood in the art. However, welding a stack of wave washers may be problematic due to the material properties of the washers, particularly when spring steel is used. In addition, welding or adhering may fail due to the adverse conditions of such an application, such as high temperature and vibration effects.

[0015] Alternatively and preferably, a stack of wave washers comprises a spacer washer disposed between neighbouring wave washers. A spacer washer suitably provides a flat surface for an adjacent wave washer to interface with and eliminates the need to join neighbouring wave washers together as the angular orientation of the wave washers about the injector axis in such an arrangement has no effect on their functionality. The number of wave washers (N) combined with the number of spacer washers (N-1) in the stack will depend on the desired spring travel.

[0016] Preferably, a stack of two wave washers comprising one spacer washer disposed between first and second wave washers is disposed between the injector body and system body. The dimensions of the wave washers and the spacer washer will depend on the dimensions of the injector and the packaging constraints around the washers. The profile and material properties of each wave washer will depend on the desired preload force.

[0017] Suitably, the first wave washer may interface with a flat surface of the injector and the second wave washer may interface with a flat surface of the system body. Where a stack of more than two wave washers is provided, the second wave washer will be a last wave washer in the stack.

[0018] Suitably, the flat surfaces may be provided by the shoulder on the injector body, defined by the reduced diameter of the projecting inlet portion, and a recess base in the system body. A suitable shoulder may be present on a readily available injector body or may form part of a custom design of injector body. Alternatively, a suitable recess in the injector may be provided and a recess base may provide a substantially flat surface. A suitable shoulder or recess may involve minimal machining of the injector body.

[0019] Preferably, the connecting means comprise a separate connecting part attached to the injector. Alternatively, the connecting part may be integral with the injector.

[0020] Preferably, the connecting part has a circular cross section and comprises a centrally disposed aperture adapted to allow the connecting part to be arranged coaxially around the projecting inlet portion of the injector. Preferably, the connecting part comprises a shoulder suitable for the first wave washer to interface with. Preferably, the stack of washers is adapted to be arranged over and around the projecting inlet portion. Preferably, the wave washers and spacer washer(s) in the stack are annular and are coaxially arranged on the projecting inlet portion.

[0021] Preferably, the connecting part comprises one or more indexing portions to correctly locate and orientate the injector body in the system body around the injector axis. Correct location and orientation of the injector when connected with the system body is particularly important for ensuring an electrical connection, such as a socket, disposed on the injector is correctly positioned for a plug to connect therewith, for example. Suitably, the socket may be any shape which is complimentary with that of the plug. Preferably, the socket extends outwardly from the connecting part and has a longitudinal axis which is substantially perpendicular to the injector axis. Suitably, the socket may have a cylindrical axis.

[0022] Preferably, the connecting part alternatively or also comprises one or more connecting portions for connecting and retaining the injector body in the system body. Preferably, the indexing portions and the connecting portions comprise one or more protrusions outwardly extending from the connecting part which engage with a part of the system body. Suitably, the one or more protrusions may engage with a hole or recess in the system body to correctly locate and orientate the injector with the system body and to connect and retain the injector in the system body. Alternatively, the indexing portions and connecting portions may be separate. For example, the connecting portions may be suitable protrusions on the connecting part and the indexing portions may be a separate notch suitably located on the connecting part which indexes with a corresponding protrusion on the system body to correctly locate and orientate the injector therewith, or vice versa.

[0023] Preferably, the one or more outwardly extending protrusions comprise two arms. Preferably, the arms are vertically orientated in a direction substantially parallel with the longitudinal axis of the injector body and have an outwardly extending, perpendicular finger at a free end. Preferably, the perpendicular fingers engage with the holes or recesses formed in the system body to correctly locate and orientate the injector in the system body. Suitably, the fingers are adapted to allow engagement with the holes or recesses whilst ensuring the injector is connected with the system body. Suitably, the fingers may be substantially barb-like and each have an upper and lower edge. Preferably, once a finger is engaged with its corresponding hole or recess, the lower edge of each finger interfaces with the system body to prevent the injector detaching therefrom. Therefore, the arms and fingers provide indexing portions for correctly locating and orientating the injector with the system body and the fingers and holes or recesses allow the injector to be connected to the system body.

[0024] The perpendicular fingers and holes or recesses are also adapted to allow relative movement between the injector body and the system body, particularly when the injector body and system body are being urged apart by the one or more wave washers. Suitable gaps between the upper and lower edges of the fingers and the system body allow for this relative movement, particularly in the vertical direction. A spacing suitably provided between each arm and the connecting part provides each arm with a degree of movement, at least in the horizontal direction. The arms are adapted to provide a degree of resilience to such movement and particularly to provide outward urging of each arm. The profile and material properties of the arms provide the degree of resilience. The flexibility and resilience of the arms and the protrusion/hole or notch arrangement conveniently provide a 'snap-fit' connection.

[0025] This arrangement advantageously provides quick and easy assembly and disassembly of an injector with a fuel rail body. This arrangement connects and retains the injector in the fuel rail body and prevents it falling from the fuel rail body, particularly during handling of the sub-assembly when being assembled with a cylinder head. The removal of one or more injectors from the cylinder head is also made simple because the complete sub-assembly, including the injectors, may be removed from the cylinder head in a single step. The connecting means ensure the injector is correctly located in the fuel rail; the angular orientation of which about the injector axis is particularly important when connecting an electrical source to the injector, as described above.

[0026] An electrical connection is typically required to electrically connect the injector with a fuel injection control system. As described above, a suitable electrical connection may comprise a plug and socket arrangement wherein a part of the injector comprises the socket. Suitably, the connecting part may comprise electrical connecting means. Suitably, the electrical connecting means may comprise a plug and socket arrangement and the connecting part may comprise an electrical socket having a longitudinal axis, perpendicularly disposed on the injector relative to the longitudinal axis of the injector. The socket may be any shape which is complimentary with a suitable plug. Suitably, the socket may be substantially cylindrical. Suitably, the connecting part may be a plastics material and may be formed by injection moulding. This advantageously reduces manufacturing costs.

[0027] Suitably, the projecting inlet portion of the injector may comprise at least one 'O'-ring to provide an effective seal between the projecting inlet portion and the bore of the system body to prevent fuel leakage past this projecting inlet portion/bore interface.

[0028] A fuel injection system comprising an injector clamping sub-assembly as described above is also provided.

[0029] A connecting part for arrangement on a projecting inlet portion of a fuel injector is also provided. The connecting part comprises one or more indexing portions for locating and correctly orientating the injector in a system body around an injector axis, wherein the indexing portions comprise one or more protrusions outwardly extending from the connecting part which engage with holes or recesses in the system body to retain the injector therein whilst allowing relative movement between the injector and the system body.

[0030] An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings:

• Figure 1 shows a partial section through a clamping sub-assembly including an injector body, connecting part and fuel rail body;
• Figure 2 shows a detailed partial section through the upper part of the clamping sub-assembly of Figure 1;
• Figure 3 shows detail P of Figure 2 showing the wave washer and spacer washer stack;
• Figure 4 shows the projecting inlet portion of the injector and the connecting part;
• Figure 5 shows the projecting inlet portion of the injector body of Figure 4 being slidably inserted into the bore of the fuel rail body during assembly;
• Figure 6 shows the injector assembled with the fuel rail body to form the sub-assembly;
• Figure 7 shows a side view of the sub-assembly of Figure 6;
• Figure 8 shows plan view of the sub-assembly of Figure 7; and
• Figure 9 shows the sub-assembly being offered up to a cylinder head.

[0031] As shown in Figure 1, a clamping sub-assembly 10 comprises an injector 11 having an elongate injector body 12 and a projecting inlet portion 18, and a fuel rail body 14 having a bore 20 which receives and retains the projecting inlet portion 18 to form the sub-assembly 10. The injector body 12 and projecting inlet portion 18 are substantially tubular and share a common longitudinal axis 13. The projecting inlet portion 18 is of reduced diameter to the injector body 12 to define a radial shoulder 19 on the injector body 12. A connecting part 16 is attached to the injector 11 and has a centrally disposed aperture 17 to allow it to fit over the projecting inlet portion 18 and sit on the shoulder 19. The aperture 17 is complimentarily shaped with the projecting inlet portion 18 to securely attach the connecting part 16 to the injector 11.

[0032] With reference to Figure 2, the connecting part 16 further comprises two vertical arms 48 outwardly extending from the connecting part 16. These arms 48 may be integrally formed with the connecting part 16. Each arm 48 comprises a perpendicular finger 50 extending outwardly from a free end which engages and indexes with a hole or recess 52 in the fuel rail body 14 whilst allowing relative movement between the injector body 12 and the fuel rail body 14. Each arm 48 is spaced (shown by 36) from the main body of the connecting part 16 to allow for flexible movement of the arm 48, particularly in the horizontal direction. Each arm 48 is provided with a degree of flexibility and resilience by its material properties and profile to ensure they are outwardly urged and return to their original vertical position after being flexed, i.e. the arms 48 are adapted to behave substantially elastically. The arms 48 and holes or recesses 52 thereby conveniently provide a quick and simple 'snap-fit' connection for connecting the injector 11 with the fuel rail body 14. The fingers 50 are substantially barb-like to prevent the injector 11 detaching from the fuel rail body 14 when connected therewith. Each finger 50 has an upper edge 51 and a lower edge 53. The lower edge 53 interfaces with its corresponding hole or recess 52 to prevent the injector 11 falling from the fuel rail body 14 when assembled therewith and particularly during handling of the sub-assembly 10.

[0033] The arms 48 also provide a means for correctly locating the injector 11 in the fuel rail 14; the angular orientation of which about the injector axis 13 is particularly important for connecting an electrical source to the injector 11 via the electrical connection 40, as shown in Figure 4. The electrical connection 40 may comprise a plug (not shown) and socket 40 arrangement wherein the socket 40 is perpendicularly disposed in or on the connecting part 16 relative to the injector axis 13. The injector 11 must be orientated correctly about its axis 13 to allow a plug (not shown) to be electrically connected with the socket 40. The arms 48 engaging and indexing with the holes or recesses 50 ensure correct orientation of the injector 11 and the socket 40 is possible. As shown, the socket 40 is substantially cylindrical to engage with a substantially cylindrically shaped plug (not shown). The socket 40 has a cylindrical axis orientated substantially perpendicularly to the injector axis 13. However, the socket 40 may be any suitable shape which is complimentary with a plug to provide a suitable electrical connection. Socket protrusions 41 disposed on the socket 40 engage with suitable clips on the plug to ensure the electrical connection is adequately secure to withstand vibrations, for example.

[0034] To provide the sub-assembly 10 with the desired preload when clamping the sub-assembly 10 to a cylinder head, as described above, two wave washers 26, 28 are provided between the connecting part 16 and the fuel rail body 14. Detail of this arrangement is shown in Figure 3. The wave washers 26, 28 are arranged over the projecting inlet portion 18 of the injector 11 and urge the injector body 12 and fuel rail body 14 apart. A spacer washer 30 separates the two wave washers 26, 28 to form a washer 'stack' 26, 28, 30. Flat surfaces for the wave washers 26, 28 to interface with are suitably provided by a shoulder 32 on the connecting part 16 and the base 34 of a recess in the fuel rail body 14. The wave washers 26, 28 also interface with the substantially flat upper and lower surfaces of the spacer washer 30. The washer stack 26, 28, 30 and connecting part 16 conveniently share the longitudinal axis 13 of the injector 11.

[0035] As described above, disposing a spacer washer 30 between two wave washers 26, 28 arranged in series, eliminates the need to join the wave washers 26, 28 together and their angular orientation in the stack 26, 28, 30 advantageously becomes unimportant. The washer stack 26, 28, 30 is conveniently free to rotate about the longitudinal axis 13 of the projecting inlet portion 18. Assembly of the washer stack 26, 28, 30 on the injector body 12 is also quick, simple and inexpensive.

[0036] With reference to Figures 2 and 3, a first set of gaps 42, 43 is provided between the connecting part 16 and the fuel rail body 14, to allow for the relative movement between the injector 11 and the fuel rail body 14 when the wave washers 26, 28 are urging the injector body 12 and fuel rail body 14 apart and when the washers 26, 28 are being compressed during clamping of the sub-assembly 10 with a cylinder head. Spacings 42 between the upper edge 51 of each finger 50 and the fuel rail body 14 also allow the injector 11 to move in a vertical direction relative to the fuel rail body 14.

[0037] A second set of gaps 44, 46 is provided to allow for positional tolerances between, and diameter tolerances on, the injector 11, fuel rail body 14, washer stack 26, 28, 30 and/or connecting part 16.

[0038] To connect an injector 11, as described above, to a suitably adapted fuel rail 14, a first wave washer 26 is first placed over the projecting inlet portion 18 to interface with the shoulder 32 on the connecting part 16. A spacer washer 30 is then placed on top of the first wave washer 26. A second wave washer 28 is then placed on top of the spacer washer 30 to form a washer 'stack' 26, 28, 30, as shown in Figure 4.

[0039] As shown in Figure 5, the injector 11, including the washer 'stack' 26, 28, 30, is offered up to the fuel rail body 14 (in the direction of arrow A) and the projecting inlet portion 18 is slidably inserted into and received by the bore 20 in the fuel rail body 14. If required, 'O'-rings (22, 24 shown in Figure 2) are provided on the projecting inlet portion 18 to seal the connecting interface between the projecting inlet portion 18 and the bore 20.

[0040] The fingers 50 at the free ends of arms 48 are engaged with the holes or recesses 52 to connect the injector 11 with the fuel rail body 14 in a 'snap-fit' manner. The washer stack 26, 28, 30 urges the injector 11 and fuel rail body 14 apart. The injector 11 is thereby subject to a preload whilst being retained in the fuel rail body 14 and is prevented from falling from the fuel rail body 14 during handling.

[0041] As shown in Figures 6 to 8, the injector 11 and fuel rail body 14 connect to form a clamping sub-assembly 10. The 'snap-fit' connection ensures the injector 12 is orientated correctly about the injector axis 13 in the fuel rail body 14. This is particularly convenient for connecting an electrical source, e.g. a plug, to the injector 12 via the electrical connection 40, e.g. a socket, at a later stage of the assembly process, as described above.

[0042] As shown in Figure 9, the sub-assembly 10 of one or more injectors 11 and the fuel rail 14 may then be offered up to a cylinder head 80 of an engine. The outlet end 86 of an injector 11 is received by an injector bore 82 in the cylinder head 80. When all injectors 11 have been correctly inserted into the corresponding bores 82 in the cylinder head 80, the fuel rail 14 may be secured to the cylinder head 80 via bolt holes 62 in the fuel rail 14 and bolt holes 84 in the cylinder head 80 to effectively clamp the injectors 11 in situ to form the complete clamping assembly. The clamping force applied to bolts (not shown), for example, to clamp the fuel rail 14 to the cylinder head 80 must at least partially compress the washer stack 26, 28, 30 to overcome all or some of the preload provided by the wave washers 26, 28.

[0043] The handling of the sub-assembly 10 when clamping with the cylinder head 80 is made efficient by the 'snap-fit' connection means 48, 50 and removal of one or more injectors 11 from the cylinder head 80 is made simple because the sub-assembly 10, including the injectors 11, may be removed from the cylinder head 80 in a single step. Quick and easy disassembly of an injector 11 from the fuel rail body 14 is also provided.

Claims

1. An injector clamping sub-assembly (10) for clamping to a cylinder head (80), the sub-assembly (10) comprising:

- a fuel injector (11) having an elongate injector body (12), a projecting inlet portion (18) having an inlet, and an outlet portion (86);

- a system body (14) having a bore (20) adapted to receive the projecting inlet portion (18) and connect the inlet within the system body (14);

- one or more wave washers (26, 28) disposed between the injector body (12) and the system body (14) to urge the injector body (12) and system body (14) apart; and

- connecting means (48, 50, 52) to locate and retain the projecting inlet portion (18) in said bore (20) whilst allowing relative movement between the injector body (12) and the system body (14).

2. An injector clamping sub-assembly (10) according to claim 1, wherein the projecting inlet portion (18) is complementarily shaped with the bore (20) to allow the projecting inlet portion (18) to engage with and be guided by the bore (20) when slidably inserted therein to connect the inlet within the system body (14).

3. An injector clamping sub-assembly (10) according to claim 1 or 2, wherein a spacer washer (30) is disposed between first and second neighbouring wave washers (26, 28).

4. An injector clamping sub-assembly (10) according to any preceding claim, wherein the connecting means comprises a separate connecting part (16) coaxially arranged on the projecting inlet portion (18) of the injector (11) and one of the wave washers (26, 28) interfaces with the connecting part (16).

5. An injector clamping sub-assembly (10) according to claim 4, wherein the connecting part (16) comprises one or more indexing portions (48, 50) for correctly locating and orientating the injector body (12) in the system body (14) around an injector axis (13).

6. An injector clamping sub-assembly (10) according to claim 4 or 5, wherein the connecting part (16) comprises one or more connecting portions (48, 50) for connecting and retaining the injector body (12) in the system body (14).

7. An injector clamping sub-assembly (10) according to claim 5 or claim 6, wherein the indexing portions and/or connecting portions (48,50) comprise one or more protrusions (48, 50) outwardly extending from the connecting part (16) which engage with holes or recesses (52) in the system body (14).

8. An injector clamping sub-assembly (10) according to claim 7, wherein the protrusions (48, 50) comprise two vertically orientated arms (48) each having an outwardly extending, perpendicular finger (50) at a free end which correspond with the holes or recesses (52).

9. An injector clamping sub-assembly (10) according to claim 7 or 8, wherein the protrusions (48, 50) are integrally formed with the connecting part (16).

10. An injector clamping sub-assembly (10) according to any one of claims 4 to 9, wherein the connecting part (16) comprises electrical connection means (40).

11. A fuel injection system comprising an injector clamping sub-assembly (10) according to any one of claims 1 to 10.

12. A connecting part (16) for arrangement on a projecting inlet portion (18) of a fuel injector (11), comprising one or more indexing portions (48, 50) for correctly locating and orientating the injector (11) in a system body (14) around an injector axis (13), and one or more connecting portions to connect and retain the injector (11) in the system body (14), whilst allowing relative movement between the injector (11) and the system body (14).

13. A connecting part (16) according to claim 12, wherein one or more protrusions (48, 50) comprise the indexing portions (48, 50) and connecting portions (48, 50) which outwardly extend from the connecting part (16) to engage with holes or recesses (52) in the system body (14).

14. A connecting part (16) according to claim 12 or 13 comprising a shoulder (32) or recess for a wave washer (26) to interface with when one or more wave washers (26, 28) are disposed between the connecting part (16) and the system body (14) to urge the injector (11) and system body (14) apart.

15. A connecting part (16) according to any one of claims 12 to 14 comprising electrical connection means (40).

Drawing