Volume divider for a fuel delivery system

Abstract

According to an aspect of the present application, there is provided a radially deformable volume splitter (100; 200) for a fuel injection system (1) of a spark-ignition engine (2). The volume splitter (100; 200) can be tubular and elongate, extending along a longitudinal axis from a first end (102) to a second end (104). The volume splitter (100; 200) can comprise a deformable longitudinal slot (116) operable to deform the volume splitter (100; 200) radially from a first state for insertion into a cavity (18; 218) of the emulsion injection common rail (10) to a second state for use within the cavity (18; 218), and a set of slots (112a-112k) arranged on an outer surface (106) of the volume splitter (100; 200) to connect, in use, an inlet (20) of the cavity (18; 218) to one or more outlets (22a-22d) of the cavity (18; 218).

Description

TECHNICAL FIELD

[0001] The present invention relates to common rails of fuel delivery systems, and in particular to volume splitters for common rails of emulsion injection systems for delivering water-fuel emulsion to internal combustion engines. BACKGROUND

[0002] It is known to provide a fluid delivery system to deliver fuel, such as gasoline, to an internal combustion engine (ICE) of a vehicle. In a popular arrangement, the fluid delivery system is a fuel injection system that delivers fuel to the engine by means of an array of fuel injectors supplied with fuel from a pressurised accumulator, known as a common rail. Typically, the common rail is controlled to regulate the amount of fuel delivered to the fuel injectors, and the fuel injectors are selectively controlled to inject the supplied fuel into the engine.

[0003] Modern fluid injection systems also include a water injection system that delivers water into the combustion chambers of the engine to reduce the tendency of the engine to knock. Injecting water in this way also provides other benefits, such as increasing fuel economy and engine performance and reducing engine emissions.

[0004] In known systems, water can be introduced by means of port injection (into the intake manifold), direct injection (into the engine cylinder) or emulsion injection, in which water is mixed with fuel and injected directly into the engine cylinder as a water-gasoline emulsion.

[0005] Emulsion injection systems typically consume less water and require fewer components. However, it is important that the emulsion is expelled from the common rail at high velocity and that the emulsion is evenly distributed to the individual fuel injectors to maintain the homogeneity of the water-fuel emulsion.

[0006] It is against this background that the present invention has been devised. SUMMARY

[0007] According to one aspect of the present invention, there is provided a radially deformable volume splitter for an emulsion injection common rail of a fuel injection system for a spark-ignition engine. The volume splitter is tubular (i.e. hollow) and elongate, extending along a longitudinal axis from a first end to a second end. The volume splitter comprises a deformable longitudinal slot operable (i.e. usable) to deform the volume splitter radially from a first state for insertion into a cavity of the emulsion injection common rail to a second state for use within the cavity; and a set of slots arranged on an outer surface of the volume splitter to connect an inlet of the cavity to one or more outlets of the cavity when in use.

[0008] The set of slots can include one or more slots that define a fluid delivery channel to deliver pressurized fluid, such as a water-fuel emulsion, to an array of fuel injectors connected with one or more outlets of the cavity.

[0009] Advantageously, the deformable longitudinal slots reduce the radial stiffness of the tubular volume divider, and thus can be manipulated (e.g., expanded or contracted) to radially deform the volume divider during installation to achieve a desired fit between the volume divider and the cavity in the second state.

[0010] With this arrangement, it is contemplated that the present invention will provide for easier common rail manufacturing and improved control over the fit and / or clearance between the volume divider and the common rail. This can enhance control over fluid delivery and can maximize the homogeneity of the water-fuel emulsion delivered to the fuel injectors.

[0011] The deformable longitudinal slots are operable to expand and / or contract the longitudinal slots, thereby radially deforming the volume divider. In other words, manipulating the deformable longitudinal slots can include expanding the longitudinal slots by causing the longitudinal slots to separate and / or contracting the longitudinal slots by causing the longitudinal slots to come together or close. In other embodiments, the deformable longitudinal slots are operable to change the shape of the volume divider, e.g., to better fit cavities of different shapes in the common rail.

[0012] In one embodiment, the volume divider can be elastic, e.g., formed of an elastic material. For example, the volume divider can be formed of a metal, a plastic, or a composite of metal and plastic. In this case, the volume divider can have a rest state or shape that is neither in tension nor in compression, and the elasticity of the volume divider can cause the volume divider to return to the rest state when the volume divider is deformed.

[0013] Optionally, the deformable longitudinal slots are operable to radially deform the volume divider to the first state. The elasticity of the volume divider can be configured to cause the volume divider to the second state for use within the cavity. For example, the deformable longitudinal slots can be contracted to radially deform the volume divider to the first state, and the elasticity of the volume divider can be configured to cause the longitudinal slots to expand, thereby deforming the volume divider to the second state for use within the cavity. In another embodiment, the longitudinal slots can engage with complementary longitudinal ridges of the cavity. For example, the longitudinal slots can be caused to separate from the first state to receive longitudinal ridges of the cavity. Once expanded, the elasticity of the volume divider can be configured to cause the longitudinal slots to contract toward the first state, thereby engaging the longitudinal ridges of the cavity in the second state.

[0014] In one embodiment, the longitudinal slots are operable to deform the volume splitter radially such that, in the second state, an outer radius of the volume splitter is greater than or equal to a radius of the chamber of the emulsion injection common rail. In this way, in use, an interference fit can be formed between the volume splitter and the chamber.

[0015] In one embodiment, the volume splitter can be configured to form a clearance fit with the chamber of the emulsion injection common rail in the second state. The longitudinal slots of the volume splitter can be operable to deform the volume splitter radially such that, in the second state, a clearance between the volume splitter and the chamber is less than or equal to 1 millimetre, optionally, in the second state, the clearance between the volume splitter and the chamber is less than or equal to 0.05 millimetres. Such a clearance is sufficiently small to minimise leakage from the set of slots (sufficient to minimise leakage) and to maintain the homogeneity of the water-fuel emulsion.

[0016] For example, the volume splitter can comprise a locking structure engageable with a complementary locking structure in the chamber of the emulsion injection common rail to substantially inhibit rotation of the volume splitter relative to the chamber of the emulsion injection common rail. Advantageously, the locking structure can ensure that the set of slots remain aligned with the inlet and the one or more outlets, thereby maintaining the connection therebetween.

[0017] Optionally, the locking structure can extend radially from an outer surface of the volume splitter to engage a complementary radial structure on a wall of the chamber (in the form of a complementary locking structure). Optionally, the locking structure can extend axially from at least one of the first end and / or the second end of the volume splitter to engage a complementary axial structure of a respective end of the chamber.

[0018] In one embodiment, the locking structure can be (arranged on the volume splitter so as to be able to) engage with a complementary locking structure in the chamber in the event that the volume splitter is oriented such that the set of slots connects the inlet of the chamber to the one or more outlets of the chamber. In this way, engagement of the locking structure can ensure the orientation of the volume splitter inside the chamber in the event that the set of slots is aligned with the inlet and the one or more outlets of the chamber.

[0019] Optionally, the locking structure can be (arranged on the volume splitter so as to be able to) engage with a complementary locking structure in the chamber when the volume splitter is in the second state.

[0020] In one embodiment, the locking structure can be (arranged on the volume splitter so as to be able to) disengage from a complementary locking structure in the chamber when the volume splitter is in the first state. This enables the volume splitter to be selectively removed from the chamber.

[0021] In one embodiment, the set of slots can include one or more injector delivery slots for connecting the inlet of the cavity and one or more outlets of the cavity. Such injector delivery slots can define one or more fluid delivery channels inside the cavity between the inlet and the one or more outlets.

[0022] In one embodiment, the set of slots can include one or more end slots for connecting the one or more injector delivery slots with the internal volume (i.e., accumulator volume) of the volume splitter around the first end and / or the second end of the volume splitter. Such end slots can define a quick-acting linkage path between the injector delivery slots and the accumulator volume to provide damping of pressure pulsations as fluid is delivered to the injection engine. It has been found that such end slots can reduce dilution of the water-fuel emulsion in the accumulator volume.

[0023] Each end slot can extend from one of the injector delivery slots to one of the first end and the second end of the volume splitter. The cross-sectional area of each end slot can be greater than the cross-sectional area of the connected injector delivery slot. Optionally, the cross-sectional area of each end slot can be at least twice the cross-sectional area of the connected injector delivery slot. It has been found that the enlarged end slots have the effect of reducing pressure peaks inside the common rail.

[0024] According to another aspect of the present invention, there is provided an emulsion injection common rail for a fuel injection system of a spark-ignition engine, comprising the volume splitter of the previous aspect of the present invention. The emulsion injection common rail can include a housing defining a cavity that receives the volume splitter.

[0025] According to another aspect of the present invention, there is provided a method of installing the radially deformable volume splitter of the previous aspect of the present invention in an emulsion injection common rail for a fuel injection system of a spark-ignition engine. The method can include: configuring the volume splitter in a first state for insertion into a cavity of the emulsion injection common rail; inserting the volume splitter into the cavity; and operating the deformable longitudinal slot (e.g., expanding the longitudinal slot) of the volume splitter to radially deform the volume splitter from the first state to a second state for use within the cavity.

[0026] In one embodiment, configuring the volume splitter in the first state can include operating the deformable longitudinal slot (e.g., by contracting or compressing the longitudinal slot) to radially deform the volume splitter to the first state. Operating the deformable longitudinal slot of the volume splitter to radially deform the volume splitter from the first state to the second state for use within the cavity can include, for example, exploiting the elasticity of the volume splitter to cause the longitudinal slot to expand, thereby deforming the volume splitter to the second state.

[0027] It is understood that preferred and / or optional features of various aspects of the present invention may be incorporated into other aspects of the invention individually or in appropriate combinations. Attached Figure Description

[0028] To make the invention more readily understood, preferred and non-limiting embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which similar features are given similar reference numerals, and in the drawings:

[0029] Figure 1 An embodiment of a fuel injection system for an internal combustion engine is schematically illustrated;

[0030] Figure 2 An embodiment of the invention is shown for use Figure 1 The fuel injection system shown is an example of a common rail system;

[0031] Figure 3 It shows Figure 2 The first cross-sectional view of the common rail shown;

[0032] Figure 4 It shows Figure 2 The second cross-sectional view of the common rail shown;

[0033] Figure 5 It shows Figure 2 The third cross-sectional view of the common rail shown;

[0034] Figure 6 This is according to one embodiment of the present invention. Figure 2 A first perspective view of an exemplary common-track capacity divider shown;

[0035] Figure 7 It shows Figure 6 A second perspective view of the capacity divider shown;

[0036] Figure 8 It shows Figure 2 The cross-sectional view of the common rail shown, in which Figure 6 The capacity divider shown is arranged in the common rail in a first state;

[0037] Figure 9 It shows Figure 2 The cross-sectional view of the common rail shown, in which Figure 6 The capacity divider shown is arranged in the common rail in a second state;

[0038] Figure 10 The arrangement in Figure 6 The capacity divider shown is... Figure 2 A detailed cross-sectional view of an exemplary pair of complementary locking structures between the co-rail housings shown; and

[0039] Figure 11 shows an example of another pair of complementary locking formations between the volume splitter shown in Figure 6 Figure 2 shows a detailed cross-sectional view of another example pair of complementary locking formations between the volume splitter shown in DETAILED DESCRIPTION

[0040] Embodiments of the present application relate to a common rail for an emulsion injection system, and in particular to a common rail in which a radially deformable volume splitter is arranged.

[0041] The volume splitter is mounted within a main rail cavity of the common rail, in which a set of slots are arranged on an outer surface of the volume splitter, the slots defining high speed fluid delivery channels for delivering pressurised fluid (such as a water-fuel emulsion) to an array of fuel injectors connected to respective outlets of the cavity.

[0042] Advantageously, the volume splitter comprises deformable longitudinal slots which can reduce the radial stiffness of the tubular volume splitter. Thus, during installation, the deformable longitudinal slots can be manipulated (e.g. expanded or contracted) to radially deform the volume splitter. For example, the volume splitter can be configured in a first state for insertion into the cavity of the common rail, and once inside the cavity, the volume splitter can be expanded to a second state for use within the cavity, e.g. to achieve a desired fit between the volume splitter and the cavity in the second state.

[0043] With this arrangement, it is envisaged that the present application will provide easier common rail manufacture, improved control over the fit and / or clearance between the volume splitter and the common rail, and provide enhanced control over fluid delivery. Thus, the homogeneity of the water-fuel emulsion delivered to the fuel injectors can be maximised.

[0044] Each of the common rail arrangements described below are for emulsion injection systems for a spark-ignition (SI) engine. However, it will be appreciated that these common rail arrangements can be suitable for other uses (including delivering fuel or water in a fluid delivery system for a compression-ignition (CI) or SI internal combustion engine).

[0045] In order to provide context for the present application, Figure 1 A simplified schematic of a fuel injection system 1 for a spark-ignition engine 2 is shown. In this embodiment, the spark-ignition engine 2 is a four-cylinder engine, having four engine cylinders 4a to 4d. However, as will become apparent in the description below, embodiments of the present application are not limited to use with four-cylinder SI engines, but can be suitable for use with any two-, four-, six-, eight-, ten- or twelve-cylinder internal combustion engine, for example.

[0046] ​The fuel injection system 1 is configured to pressurise and deliver a pressurised fluid comprising a water-fuel emulsion to each cylinder 4a-d of the spark-ignition engine 2. To this end, the fuel injection system 1 takes the form of an emulsion injection system and comprises a high-pressure pump 6, a common rail 10, a pressure sensor 12 and a set of fuel injectors 14a-d. As shown, the set of fuel injectors 14a-d comprises a first fuel injector 14a, a second fuel injector 14b, a third fuel injector 14c and a fourth fuel injector 14d, each fuel injector 14a-d being configured to inject fluid directly into a respective one of the four engine cylinders 4a-d.

[0047] In use, the high-pressure pump 6 receives a supply of water and a supply of fuel (such as gasoline), which mix together. The high-pressure pump 6 pressurises the mixture to produce a pressurised fluid comprising a water and fuel emulsion and delivers it to the common rail 10. In this embodiment, the water-fuel emulsion is thus prepared by a single high-pressure pump 6 prior to being added to the common rail 10. However, it will be appreciated that in other embodiments, the fluid injection system 1 can comprise a first high-pressure pump to pressurise the fuel and a second high-pressure pump to pressurise the water. The pressurised water and pressurised fuel can be delivered to the common rail 10 separately, where a water and fuel emulsion can be formed by mixing the supplied pressurised water and fuel.

[0048] The common rail 10 is configured to accumulate a quantity of pressurised fluid, primarily for delivery to the set of fuel injectors 14a-d as required to inject into the engine 2.

[0049] Although not shown in this embodiment, the high-pressure pump 6 and / or the common rail 10 can be operated by a control system (not shown) which controls the delivery of pressurised fluid to the set of fuel injectors 14a-d. For example, the pressure sensor 12 can monitor the pressure within the common rail 10 and output a signal indicative of the pressure within the common rail 10 to the control system. The control system can then operate the high-pressure pump 6 and / or the common rail 10 to pressurise fluid and / or deliver pressurised fluid to the fuel injectors 14a-d in dependence on the signal.

[0050] Figures 2 to 10 One embodiment of a common rail 10 which can be used in the fluid delivery system 1 is provided in Figure 4 and will now be described.

[0051] Figure 2 A perspective view of the common rail 10 is shown, which is elongate and extends along a longitudinal axis. In this embodiment, the common rail 10 is substantially cylindrical, like a conventional common rail. However, the shape of the common rail 10 is not intended to limit the scope of the present invention.

[0052] Figures 3 to 5A common rail 10 is shown which comprises a housing 16 as a single component and a volume splitter 100 arranged within the housing 16. The housing 16 is shown in cross-section along a longitudinal axis of the common rail 10.

[0053] Figure 3 A perspective view of the common rail 10 is shown, Figure 4 A side view of the common rail 10 is shown, and Figure 5 A top view of the common rail 10 is shown.

[0054] As shown in Figures 3 to 5 the housing 16 comprises a cavity 18 for accumulating a volume of pressurised fluid, and the volume splitter 100 is arranged within the cavity 18 to define high speed fluid delivery passages between an inlet 20 of the cavity 18 and a plurality of outlets 22a to 22d of the cavity 18. The plurality of outlets 22a to 22d from the cavity 18 are connected to respective ones of a set of fuel injectors 14a to 14d.

[0055] In this embodiment, the cavity 18 is elongate and extends along a longitudinal axis of the common rail 10 from a first end 24 to a second end 26, as best shown in Figure 4 the first end 24 of the cavity 18 is closed by an end wall 25 of the housing 16, and the second end 26 of the cavity 18 is sealed by a plug 27. In other embodiments, for example to facilitate manufacture, the cavity 18 can be closed by a removable seal or plug at each of the first and second ends 24, 26 of the cavity 18.

[0056] In this embodiment, the cavity 18 is substantially uniform along its length, and the cavity 18 is defined by a substantially cylindrical cavity wall formed by an inner surface of the housing 16. However, it will be appreciated that in other embodiments the cavity 18 can be defined by any other suitable shape of cavity wall which can define an elongate space or void, for example the cavity 18 can have a circular, quadrilateral or elliptical cross-section.

[0057] The inlet 20 and the plurality of outlets 22a to 22d are arranged along the length of the cavity 18. The inlet 20 is provided for the addition of pressurised fluid to the cavity 18, and the housing 16 comprises an input mouth 30 which extends from the inlet 20 for connection with the high pressure pump 6. For example, the input mouth 30 can be connected with the high pressure pump 6 via a suitable supply line to provide a supply of pressurised fluid to the inlet 20 in response to demand.

[0058] The plurality of outlets 22a to 22d are provided for the delivery of pressurised fluid from the cavity 18 to the set of fuel injectors 14a to 14d. Accordingly, the housing 16 can comprise a plurality of output mouths 32a to 32d (as Figure 4Each of the plurality of outlets 22a-d extends from a respective outlet 22a-d to connect to a respective fuel injector 14a-d (as shown in

[0059] In this embodiment, the plurality of outlets 22a-d includes a first outlet 22a, a second outlet 22b, a third outlet 22c, and a fourth outlet 22d corresponding to a set of four fuel injectors 14a-d. However, it will be appreciated that the plurality of outlets 22a-d can vary with the application of the common rail 10.

[0060] The plurality of outlets 22a-d can be coplanar with the longitudinal axis of the common rail 10 (as shown in Figure 3 and Figure 4 The inlet 20 can be circumferentially spaced about the cylindrical cavity wall from the plurality of outlets 22a-d (as shown in Figure 4 and Figure 5 The inlet 20 of the cavity 18 can be disposed on an orthogonal portion of the cavity wall that is orthogonal to the plurality of outlets 22a-d (as shown with reference to

[0061] In particular, the inlet 20 of the cavity 18 is symmetrically disposed about the plurality of outlets 22a-d. More particularly, the distance between the first outlet 22a and the second outlet 22b is equal to the distance between the third outlet 22c and the fourth outlet 22d, and the inlet 20 is disposed equidistant between the second outlet 22b and the third outlet 22c, resulting in a symmetric arrangement about the inlet 20. As will become apparent in the following description, this symmetric arrangement facilitates maintaining homogeneity of the water-fuel emulsion in use.

[0062] Now considering the volume splitter 100 in more detail, the volume splitter 100 is elongate and extends along a longitudinal axis from a first end 102 to a second end 104 (as shown in Figures 3 to 5 .

[0063] The volume splitter 100 is tubular, having an outer surface 106 and an axial opening 108 extending along the length of the volume splitter 100 to define an inner surface 110 (as best shown in Figure 3 In this embodiment, the volume splitter 100 is substantially cylindrical to complement the cylindrical cavity wall, and thus the inner surface 110, outer surface 106 are substantially cylindrical.

[0064] As will become apparent in the following description, the volume splitter 100 defines various structures within the cavity 18 that are configured to optimise the delivery of pressurised fluid to the fuel injectors 14a-d.

[0065] For example, the volume splitter 100 forms an accumulator volume within the cavity 18, which is defined by the inner surface 110 of the volume splitter 100. In use, the accumulator volume 110 is filled with an amount of pressurised fluid and acts as a damping chamber (in a conventional manner) to dampen pressure pulsations resulting from the injection of pressurised fluid into the engine cylinders 4a to 4d.

[0066] It will be appreciated by the skilled person that the volume / amount required to effectively dampen pressure pulsations will depend on the particular use of the common rail 10 and the volume splitter 100 can be modified accordingly to accommodate such use. For example, the thickness of the volume splitter 100 can be reduced so as to form a larger accumulator volume 110 within the cavity 18.

[0067] The volume splitter 100 further comprises a set of slots 112a to 112k (as shown in Figures 3 to 5 ) arranged on the outer surface 106 of the volume splitter 100 to connect the inlet 20 of the cavity 18 to a plurality of outlets 22a to 22d.

[0068] In this embodiment, as shown in Figure 4 and Figure 5 , the set of slots 112a to 112k comprises: an inlet slot 112a aligned with the inlet 20 of the cavity 18; a first subset of slots 112b to 112e connected to the first outlet 22a and the second outlet 22b; and a second subset of slots 112f to 112i connected to the third outlet 22c and the fourth outlet 22d.

[0069] The inlet slot 112a extends axially along the length of the volume splitter 100 from a first end 113 to a second end 115, with the inlet 20 to the cavity 18 being arranged equidistantly between the first end 113 and the second end 115. In this way, the first end 113 and the second end 115 of the inlet slot 112a are each provided with an equal supply of pressurised fluid from the inlet 20.

[0070] At the first end 113, the inlet slot 112a is connected to the first subset of slots 112b to 112e, and at the second end 115, the inlet slot 112a is connected to the second subset of slots 112f to 112i.

[0071] The first subset of slots 112b-112e includes a first slot 112b, a second slot 112c, a third slot 112d, and a fourth slot 112e. The first slot 112b is disposed equidistant between the first outlet 22a and the second outlet 22b along the length of the volume divider 100 and extends from the inlet slot 112a to the second slot 112c around the circumference of the volume divider 100. The second slot 112c extends axially between the third slot 112d and the fourth slot 112e, and the third slot 112d and the fourth slot 112e extend circumferentially around the volume divider 100 to connect to the first outlet 22a and the second outlet 22b. In this manner, the inlet slot 112a and the first slot 112b, the second slot 112c, and the third slot 112d collectively define a first fluid transport passage 114a connecting the inlet 20 and the first outlet 22a. The inlet slot 112a and the first slot 112b, the second slot 112c, and the fourth slot 112e collectively define a second fluid transport passage 114b connecting the inlet 20 and the second outlet 22b.

[0072] The second subset of slots 112f-112i is substantially identical to the first subset of slots 112b-112e, but extends from the second end 115 of the inlet slot 112a to connect to the third outlet 22c and the fourth outlet 22d. In this manner, the second subset of slots 112f-112i defines a third fluid transport passage 114c connecting the inlet 20 and the third outlet 22c and a fourth fluid transport passage 114d connecting the inlet 20 and the fourth outlet 22d.

[0073] In this manner, the set of slots 112a-112k defines a plurality of fluid transport passages 114a-114d to transport pressurized fluid from the inlet 20 of the chamber 18 to the plurality of outlets 22a-22d.

[0074] Each of the fluid transport passages 114a-114d defines a relatively short and narrow (i.e., low volume) path through a relatively large volume of the chamber 18. Accordingly, the plurality of fluid transport passages 114a-114d minimizes (minimizes to a minimum) the time required to transport pressurized fluid from the inlet 20 to each of the outlets 22a-22d.

[0075] Importantly, the plurality of fluid transport passages 114a-114d are substantially identical and of equal volume, which defines that the fluid flows from the inlet 20 to each of the outlets 22a-22d via the same volume. This has the effect of maximizing the homogeneity of the water-fuel emulsion delivered to the set of fuel injectors 14a-14d.

[0076] It will be appreciated that the slots forming the first subset of slots 112b-112e and the second subset of slots 112f-112i can substantially match one another, with a respective one of the slots having equal width, length and / or depth (extending radially into the outer surface 106 of the volume splitter 100) to ensure that the fluid delivery passages 114a-114d are substantially equal in volume.

[0077] Furthermore, it will be appreciated that the above-described embodiments of the slot arrangement are exemplary only, and in other embodiments the set of slots 112a-112k can take various forms to define a plurality of equal-volume fluid delivery passages 114a-114d between the inlet 20 and the plurality of outlets 22a-22d.

[0078] As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100. Figure 3 and Figure 4 As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100.

[0079] As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100. Figure 3 and Figure 4 As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100.

[0080] In this way, the first end slot 112j and the second end slot 112k are configured to provide respective first and second respective linkage paths between the inlet 20 and the accumulator volume 110 (around the first and second ends of the volume splitter 100), as shown in Figs. 1 1 and 12, respectively. Figure 3 As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100. Figure 3 and Figure 4 As shown in Figs. 1 1 and 12, the set of slots 112a-112k can further include a first end slot 112j and a second end slot 112k to connect the inlet 20 with the accumulator volume 110 around the first end 102 and the second end 104 of the volume splitter 100.

[0081] In another embodiment, the volume splitter 100 can additionally or alternatively include one or more orifices (not shown) extending through the volume splitter 100 to define a linkage path between the fluid delivery channels 114a-d and the accumulator volume 110. The inventors have found that such orifices are effective to dampen pressure pulsations. However, by comparison, the orifices produce a higher degree of water dilution in the accumulator volume 110 than the end slots 112j, 112k.

[0082] The inventors have also found that the relatively large end slots 112j, 112k have the advantageous effect of reducing pressure spikes and effectively damping pressure pulsations. In particular, the cross-sectional area of each end slot 112j, 112k can be greater than the cross-sectional area of the inlet slot 112a to reduce pressure during an injection event. Preferably, the cross-sectional area of each end slot 112j, 112k can be at least twice the cross-sectional area of the inlet slot 112a. For example, each end slot 112j, 112k can have the same depth as the inlet slot 112a, but the width (extending around the circumference of the volume splitter 100) of each end slot 112j, 112k can be at least twice the width of the inlet slot 112a.

[0083] It will be appreciated that, in order for the volume splitter 100 to function in the intended manner, it is important to minimise or at least control the gap between the outer surface 106 of the volume splitter 100 and the chamber wall of the chamber 18. For example, if there is a gap between the volume splitter 100 and the chamber 18, pressurised fluid will leak from the plurality of fluid delivery channels 114a-d. The effect of the leakage is to reduce the homogeneity of the water-fuel emulsion and increase the delivery time between the inlet 20 and the plurality of outlets 22a-d.

[0084] Advantageously, to mitigate or at least control the leakage, the volume splitter 100 of the present invention includes a deformable longitudinal slot 116 that is operable, i.e. usable, to deform the volume splitter 100 radially so as to form a desired fit in the chamber 18, which will now be described with reference to Figures 6 to 9 This will be described in more detail.

[0085] Figure 6 a first perspective view of the volume splitter 100 is shown, Figure 7 a second perspective view of the volume splitter 100 is shown, which has been rotated through almost 180 degrees about its longitudinal axis.

[0086] As Figure 7As shown in FIG. 1, the longitudinal slots 116 extend from the first end 102 to the second end 104 of the volumetric divider 100, thereby dividing the volumetric divider 100 along its length. The longitudinal slots 116 have the effect of reducing the radial stiffness of the tubular volumetric divider 100, and can be deformed (e.g., expanded or caused to separate) to increase the effective radius of the volumetric divider 100. As will become apparent, the longitudinal slots 116 can also be deformed to effectively reduce the radius of the volumetric divider 100, e.g., by contracting the longitudinal slots 116, or otherwise causing the longitudinal slots 116 to come together.

[0087] It will be appreciated that the volumetric divider 100 can be formed by bending a suitably prepared strip of material into a tubular shape, or otherwise cutting longitudinal slots 116 along the length of the tube.

[0088] Accordingly, the deformable longitudinal slots 116 can be used to insert the volumetric divider 100 into the cavity 18 of the housing 16, and thereafter achieve a desired fit between the volumetric divider 100 and the cavity 18. This installation process will be described in further detail below with reference to FIGS. 4-6. Figure 8 and Figure 9 will be described in detail.

[0089] Figure 8 A cross-sectional view of the common rail 10 is shown, with the volumetric divider 100 disposed within the cavity 18, with sufficient clearance for the volumetric divider 10 to move substantially unimpeded.

[0090] To this end, the volumetric divider 100 can be configured in a first state having a radius that is less than the radius of the cavity 18. In this state, the volumetric divider 100 can be introduced into the cavity 18 via the open second end 24 of the cavity 18, and suitably positioned within the cavity 18.

[0091] Thereafter, the longitudinal slots 116 can be caused to separate, to increase the radius of the volumetric divider 100 to a second state that provides a desired fit between the volumetric divider 100 and the cavity 18.

[0092] Figure 9A cross-sectional view of the common rail 10 is shown, in which the capacity cutter 100 is arranged in a second state within the cavity 18. In this embodiment, the longitudinal slot 116 is forced apart such that, in the second state, the radius of the capacity cutter 100 is greater than or equal to the radius of the cavity 18. In this way, an interference fit is formed between the capacity cutter 100 and the cavity 18, with no gap between the outer surface 106 of the capacity cutter 100 and the cavity 18. In other embodiments, the longitudinal slot 116 may be forced apart such that a clearance fit is formed between the capacity cutter 100 and the cavity 18, wherein the gap between the capacity cutter 100 and the cavity 18 is less than or equal to 1 mm. Preferably, the longitudinal slot 116 may be forced apart such that the gap is less than or equal to 0.05 mm to maintain the homogeneity of the water-fuel emulsion.

[0093] For the context, the longitudinal slot 116 may be operated as described above to increase the radius of the capacity divider 100 by at least 5% to 10% between the first and second states, preferably by at least 5% to 15%, but generally not exceeding 20%.

[0094] It should be understood that the capacity cutter 100 can be extended to the second state in various ways, but in one embodiment, the capacity cutter 100 can be formed of an elastic material that serves to move the capacity cutter 100 toward a resting state, that is, neither in a tensile state nor a compressed state.

[0095] Therefore, in order to form an interference fit between cavity 18 and capacity divider 100, the radius of capacity divider 100 can be greater than or equal to the radius of cavity 18 in the static state. Therefore, as... Figure 8 As shown, the capacity cutter 100 can be compressed to shrink the longitudinal slot 116 and deform the capacity cutter 100 into a first state for insertion into the cavity 18. After the radial compressive force is removed, the longitudinal slot 116 can expand into a resting state within the cavity 18 due to the elasticity of the capacity cutter 100. In doing so, the radius of the capacity cutter 100 increases such that the capacity cutter 100 engages with the cavity 18 in a second state and forms an interference fit with the cavity 18, as shown. Figure 9 As shown in the image.

[0096] It should be understood that the second state may be the same as the static state in this embodiment, or the second state may be a certain compression state, so that the elasticity of the capacity cutter 100 causes the capacity cutter 100 to expand against the cavity 18.

[0097] In the first state, the longitudinal slot 116 can contract such that the span of the longitudinal slot 116 is reduced by at least 50%, preferably at least 70%, but generally no more than 90% from the at-rest state, in context. In the second state, the longitudinal slot 116 can return to the original span, or at least 75% of the original span, of the at-rest state, for example.

[0098] To provide such elasticity, the volume splitter 100 can be formed of a metal, a (heat-resistant) plastic, or a combination of materials. For example, the volume splitter 100 can include a metal inner layer and an outer plastic coating that can be molded around the metal inner layer to insulate the metal inner layer from the water-fuel emulsion. The plastic coating can have no chemical affinity for gasoline or water. In this way, the metal can be selected from a group of suitable elastic metals that can or can not be corrosion-resistant.

[0099] It should be appreciated that the metal can be selected to withstand the pressure during the injection event and provide sufficient elasticity to return to the at-rest state after insertion into the cavity 18. The plastic coating can be selected from a range of plastic materials that have high-temperature resistance and sufficient wear and erosion resistance to withstand the erosion that can occur when the pressurized fluid flows through the plurality of fluid delivery channels 114a-114d. Furthermore, the materials of the metal and the plastic coating can be matched to one another so as to complement one another, thereby ensuring that the volume splitter 100 has suitable elasticity and robustness.

[0100] It is also important that the volume splitter 100 be rotationally locked in use relative to the cavity 18, such that the set of slots 112a-112k remain aligned with the inlet 20 and the plurality of outlets 22a-22d. This rotational restriction is required because the longitudinal slot 116 precludes or prevents slots that extend circumferentially around the volume splitter 100 (as with conventional volume splitters). Instead, as shown in FIG. 1, the set of slots 112a-112k are arranged on portions of the outer surface 106 of the volume splitter 100 that are not interrupted by the longitudinal slot 116. Thus, the volume splitter 100 must be maintained in a certain orientation or a range of orientations within the cavity 18 to ensure that the inlet 20 and the plurality of outlets 22a-22d remain aligned with the corresponding connection slots 112a, 112d, 112e, 112h, 112i. Figure 6

[0101] ​To this end, the volume divider 100 can include a locking structure that engages a complementary structure in the cavity 18 to substantially inhibit relative rotation. For example, the volume divider 100 and the housing 16 can include a pair of complementary locking structures that inter-engage, which can extend between the cavity 18 and the volume divider 100 to substantially inhibit relative rotation. Such locking structures can extend radially between the cavity 18 and the volume divider 100, or longitudinally between the first end 102 and / or the second end 104 of the volume divider 100 and the cavity 18.

[0102] By way of example, Figure 10 A detailed cross-sectional view of the volume divider 100 arranged within the cavity 18 is shown.

[0103] As Figure 10 As shown in the middle, the volume divider 100 can include a radially extending recess 118 in the outer surface 106, and the housing 16 can include a complementary radially extending protrusion 120 in the form of a pin. The radially extending protrusion 120 can be configured to engage the recess 118 with the volume divider 100 properly oriented in the cavity 18 (i.e., the set of slots 112a-k are aligned with the inlet 20 and the plurality of outlets 22a-d, and the volume divider 100 is expanded to the second state). Once engaged with the recess 118, the radially extending protrusion 120 can substantially inhibit rotation of the volume divider 100 within the cavity 18. When the volume divider 100 is compressed to the first state, the radially extending protrusion 120 can disengage the recess 118, thereby allowing the volume divider 100 to move unimpeded in the cavity 18.

[0104] It should be appreciated that while the volume divider 100 can be installed within the cavity 18 in an interference fit that inhibits rotation of the volume divider 100 within the cavity 18, the locking structures 118, 120 can include a secondary locking mechanism between the volume divider 100 and the cavity 18 that inhibits relative rotation. For example, in the event that pressure in the common rail 10 is great enough to overcome the frictional force of the interference fit, the locking structures 118, 120 can inhibit rotation of the volume divider 100 in the cavity 18. If the volume divider 100 is installed in the cavity 18 in a clearance fit, allowing the volume divider 100 to have some rotation, it should be appreciated that the locking structures 118, 120 can engage to substantially inhibit such rotation.

[0105] However, such an arrangement is not meant to be limiting, Figure 11 A detailed cross-sectional view of another example volume divider 200 arranged within a cavity 218 of another example housing 216 is shown.

[0106] The volume splitter 200 and the housing 216 can be substantially as described in the previous embodiments and in the following description, like reference numerals are used to indicate like features. In this embodiment, the volume splitter 200 can comprise a locking formation in the form of a radial protrusion 222 located on the second end 104 of the volume splitter 200. As shown, the housing 216 can comprise a complementary recess 224 at the second end 24 of the cavity 218 and the radial protrusion 222 can be received in the recess 224 to substantially inhibit rotation of the volume splitter 200 in the cavity 218.

[0107] Once the volume splitter 100 is suitably installed in the cavity 218 of the housing 18, the common rail 10 can be operated as follows.

[0108] In response to the demand for pressurised fluid supply by the fuel injectors 4a to 4d, the high pressure pump 6 of the fuel injection system 1 is configured to deliver a supply of pressurised fluid comprising a water and fuel emulsion to the inlet 20.

[0109] The pressurised fluid then enters the inlet slot 112a of the volume splitter 100 and is split into two equal portions. The first portion proceeds in equal proportion along the first and second fluid delivery channels 114a and 114b to the first and second outlets 22a and 22b. The second portion proceeds in equal proportion along the third and fourth delivery channels 114c and 114d to the third and fourth outlets 22c and 22d.

[0110] It will be appreciated that the plurality of outlets 22a to 22d receive equal volumes / amounts of pressurised fluid because the inlet 20 is equidistantly arranged between the first and second ends 116 and 118 of the inlet slot 112a and the plurality of fluid delivery channels 114a to 114d define equal volumes via which the pressurised fluid flows from the inlet 20 to each of the outlets 22a to 22d.

[0111] Accordingly, each fuel injector 14a to 14d is provided with an equal volume of pressurised fluid flow which results in a parallel rather than a series injection arrangement. The parallel injection arrangement improves the homogeneity of the water and fuel emulsion injected from the fuel injectors 14a to 14d.

[0112] Furthermore, the volume of pressurized fluid flowing in each fluid delivery passage 114a-d is minimized while not creating excessive or undue back pressure, and thus each fluid delivery passage 114a-d defines a high speed flow path through the cavity 18 that minimizes the time (e.g., in response to demand) for delivery of pressurized fluid to the fuel injectors 14a, 14b. This short response time is advantageous for several reasons. For example, the short response time can maximize the homogeneity of the water and fuel emulsion in the pressurized fluid (maximize homogeneity), which has a tendency to separate if the pressurized fluid takes too long to reach the fuel injectors 14a-d, thereby destroying the homogeneity of the mixture.

[0113] To further reduce the response time, the high pressure pump 6 can be configured to deliver pressurized fluid at a high pressure, thereby causing the fluid to flow through the fluid delivery passages 114a-d at a faster rate. However, this high pressure flow of pressurized fluid creates a large pressure surge as the fluid enters the cavity 18. Advantageously, the end slots 112j, 112k define a linkage path between the inlet slot 112a and the accumulator volume 110 that contains a volume of pressurized fluid that dampens the pressure pulse. If the pressure pulse were not dampened, the homogeneity of the pressurized fluid can be affected.

[0114] After the pressurized fluid is injected into the engine 2, the pressurized fluid can enter the accumulator volume 110 from the fluid delivery passages 114a-d to maintain an effective damping volume. For example, excess pressurized fluid can flow into the accumulator volume 110 along the first end slot 112j and the second end slot 112k and around the first end 102 and the second end 104 of the volume divider 100.

[0115] Those skilled in the art will understand that the application can be varied in many alternative forms without departing from the scope of the appended claims.

[0116] In another embodiment, the cavity 18 can include a longitudinal ridge that is complementary to the longitudinal slot 116 of the volume divider 100. The longitudinal ridge can engage with the longitudinal slot 116 as a locking structure to inhibit rotation of the volume divider 100 within the cavity 18 and / or to cause the longitudinal slot 116 to separate, thereby creating a desired fit between the cavity 18 and the volume divider 100 in the second state. For example, the volume divider 100 can be formed of a resilient material, and in the at rest state, the longitudinal slot 116 can be too narrow to receive the longitudinal ridge. Accordingly, the longitudinal slot 116 can expand to be inserted into the cavity 18 and engage with the longitudinal ridge. Thereafter, the resilience of the volume divider 100 can cause the longitudinal slot 116 to close, but the longitudinal slot 116 can be held apart by the longitudinal ridge. Accordingly, the volume divider 100 can maintain a larger radius to engage with the cavity 18 to create a desired fit, such as an interference fit. It should be appreciated that the engagement between the longitudinal slot 116 and the longitudinal ridge can substantially inhibit rotation of the volume divider 100 within the cavity 18.

[0117] Reference Signs Used

[0118] 1 - fluid injection system

[0119] 2 - spark-ignition engine

[0120] 4a to 4d) - engine cylinder

[0121] 6 - high-pressure pump

[0122] 10 - common rail

[0123] 12 - pressure sensor

[0124] 14a to 14d) - fuel injector

[0125] 16 - common rail housing

[0126] 18 - cavity

[0127] 20 - inlet

[0128] 22a to 22d - plurality of outlets

[0129] 24 - first end

[0130] 25 - end wall

[0131] 26 - second end

[0132] 27 - plug

[0133] 30 - input nozzle

[0134] 32a to 32d - output nozzle

[0135] 100 - volume divider

[0136] 102 - first end of volume splitter

[0137] 104 - second end of volume splitter

[0138] 106 - outer surface of volume splitter

[0139] 108 - opening

[0140] 110 - inner surface of volume splitter / accumulator volume

[0141] 112a to 112k - set of slots

[0142] 113 - first end (of inlet slot)

[0143] 114a to 114d - plurality of fluid transport channels

[0144] 115 - second end (of inlet slot)

[0145] 116 - longitudinal slot

[0146] 118 - recess

[0147] 120 - protrusion

[0148] 200 - volume splitter (second embodiment)

[0149] 216 - housing (second embodiment)

[0150] 218 - cavity (second embodiment)

[0151] 222 - protrusion

[0152] 224 - recess

Claims

1. A radially deformable volume splitter (100; 200) for an emulsion injection common rail (10) of a fuel injection system (1) of a spark-ignition engine (2), wherein, The volume splitter (100; 200) is tubular and elongate, extending along a longitudinal axis from a first end (102) to a second end (104); and wherein the volume splitter (100; 200) comprises: a deformable longitudinal slot (116) operable to deform the volume splitter (100; 200) radially from a first state for insertion into a cavity (18; 218) of the emulsion jet common rail (10) to a second state for use within the cavity (18; 218); and a set of slots (112a to 112k) arranged on an outer surface (106) of the volume splitter (100; 200) to connect, in use, an inlet (20) of the cavity (18; 218) to one or more outlets (22a to 22d) of the cavity (18; 218), the set of slots (112a to 112k) comprising: one or more injector delivery slots (112a to 112i) to connect the inlet (20) of the cavity (18; 218) to the one or more outlets (22a to 22d) of the cavity (18; 218); and a plurality of end slots (112j to 112k) to connect the one or more injector delivery slots (112a to 112i) to an internal volume of the volume splitter (100; 200) around the first end (102) and the second end (104) of the volume splitter (100; 200).

2. The volume slicer (100; 200) according to claim 1, wherein The deformable longitudinal slot (116) is operable to expand and / or contract the longitudinal slot (116), thereby deforming the volume splitter (100; 200) radially.

3. The volume slicer (100; 200) according to claim 1, wherein The volume splitter (100; 200) is formed from an elastic material.

4. The volume slicer (100; 200) according to claim 3, wherein The deformable longitudinal slot (116) is operable to deform the volume splitter (100; 200) radially to the first state; and wherein the elasticity of the volume splitter (100; 200) is configured to urge the volume splitter (100; 200) to the second state for use within the cavity (18; 218).

5. The volume slicer (100; 200) according to claim 1, wherein The longitudinal slot (116) is operable to deform the volume splitter (100; 200) radially such that, in the second state, an outer radius of the volume splitter (100; 200) is greater than or equal to a radius of the cavity (18; 218) of the emulsion jet common rail (10) so as to form, in use, an interference fit between the volume splitter (100; 200) and the cavity (18; 218). The deformable longitudinal slot (116) is operable to deform the volume splitter (100; 200) radially such that, in the second state, an outer radius of the volume splitter (100; 200) is greater than or equal to a radius of the cavity (18; 218) of the emulsion jet common rail (10) so as to form, in use, an interference fit between the volume splitter (100; 200) and the cavity (18; 218).

6. The volume slicer (100; 200) according to claim 1, wherein The volume splitter (100; 200) is configured to form a clearance fit with the cavity (18; 218) of the emulsion jet common rail (10) in the second state; and wherein the longitudinal slot (116) of the volume splitter (100; 200) is operable to deform the volume splitter (100; 200) radially such that the clearance between the volume splitter (100; 200) and the cavity (18; 218) is less than or equal to 1 millimeter in the second state.

7. The volume splitter (100; 200) of claim 1, further comprising a locking feature (118; 222) engageable with a complementary locking feature (120; 224) in the cavity (18; 218) of the emulsion jet common rail (10) to substantially inhibit rotation of the volume splitter (100; 200) relative to the cavity (18; 218) of the emulsion jet common rail (10).

8. The volume slicer (100; 200) according to claim 7, wherein The locking feature (118; 222) extends radially from the outer surface (106) of the volume splitter (100; 200) to engage a complementary radial feature (120; 224) on a wall of the cavity (18; 218), or the locking feature extends axially from at least one of the first end (102) and / or the second end (104) of the volume splitter (100; 200) to engage a complementary axial feature in the respective end (22, 24) of the cavity (18).

9. The volume slicer (100; 200) according to claim 7, wherein The locking feature (118; 222) is engageable with the complementary locking feature (120; 224) in the cavity (18; 218) with the volume splitter (100; 200) oriented such that the set of slots (112a-112k) connect the inlet (20) of the cavity (18; 218) with the one or more outlets (22a-22d) of the cavity (18; 218).

10. The volume slicer (100; 200) according to claim 7, wherein The locking feature (118; 222) is engageable with the complementary locking feature (120; 224) in the cavity (18; 218) when the volume splitter (100; 200) is in the second state.

11. The volume slicer (100; 200) according to claim 10, wherein The locking feature (118; 222) is disengageable from the complementary locking feature (120; 224) in the cavity (18; 218) when the volume splitter (100; 200) is in the first state.

12. The volume slicer (100; 200) according to claim 1, wherein Each end slot (112j-112k) extends from one of the injector delivery slots (112a-112i) to one of the first end (102) and the second end (104) of the volume splitter (100; 200), and wherein a cross-sectional area of each end slot (112j-112k) is greater than a cross-sectional area of the connected injector delivery slot (112a-112i).

13. The volume slicer (100; 200) according to claim 6, wherein In said second condition, said gap between said volume splitter (100; 200) and said cavity (18; 218) is less than or equal to 0.05 millimeters.

14. The volume slicer (100; 200) according to claim 12, wherein Said cross-sectional area of each end slot (112j to 112k) is at least twice the cross-sectional area of the connected injector delivery slot (112a to 112i).

15. An emulsion injection common rail (10) for a fuel injection system (1) of a spark-ignition engine (2), said emulsion injection common rail comprising a volume splitter (100; 200) according to any one of claims 1 to 14.

16. A method of installing a radially deformable volume splitter (100; 200) according to any one of claims 1 to 14 in an emulsion injection common rail (10) of a fuel injection system (1) for a spark-ignition engine (2), the method comprising: configuring said volume splitter (100; 200) in said first condition for insertion into a cavity (18; 218) of said emulsion injection common rail (10); inserting said volume splitter (100; 200) into said cavity (18; 218); and operating said deformable longitudinal slot (116) of said volume splitter (100; 200) to radially deform said volume splitter (100; 200) from said first condition to said second condition for use within said cavity (18; 218).

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