Injector mount

Abstract

An injector mount 100 for securing an injector 150 for injecting a fluid (such as urea) into an exhaust pipe comprising an internal channel 108 having a surface 110 defining a flow path, wherein the s

Description

FIELD The present invention relates to an injector mount, and in particular but not exclusively to an injector mount for securing an injector for injecting a fluid to a vehicle exhaust pipe. BACKGROUND Vehicles which are powered by diesel engines often utilise selective catalytic reduction (SCR) to reduce emissions of nitrogen oxides (NOx). SCR typically uses injectors to inject a reducing agent (commonly known as AdBlue® or Urea) into the flow of exhaust gases in the vehicle exhaust pipe. The injectors are typically secured to the vehicle exhaust pipe using an injector mount. However, injectors secured to the vehicle exhaust pipe using conventional injector mounts are prone to premature failure, at approximately 30,000 miles in some cases. The injectors are typically costly components which can be difficult to replace, and injectors failing or becoming inoperable after a relatively short working life unnecessarily increases servicing requirements. The present invention has been devised with the foregoing in mind. SUMMARY According to a first aspect there is provided an injector mount for securing, to a vehicle exhaust pipe, an injector for injecting a fluid into the vehicle exhaust pipe. The mount may comprise a main body configured to support the injector in use. The main body may comprise an internal channel. A part of the internal channel may define a flow path for fluid from the injector towards the exhaust pipe in use. A surface of the part of the internal channel defining the flow path may be configured to inhibit build-up or adhesion of material on the surface. Due to the proximity of the injector mount and the injector towards the vehicle exhaust pipe in use, heat from the exhaust gases and vehicle exhaust system can be transferred to the injector mount, the injector and the fluid within the injector. The high temperatures experienced can cause the fluid (both before and after release from the injector) to crystallise, particularly for selective catalytic reduction fluids (commonly known as AdBlue® or Urea). The crystallised 2 material can build up both on the injector mount and the injector to an extent that no fluid can be injected from the injector into the vehicle exhaust pipe, rendering the injector inoperable. Providing a surface on the part of the internal channel defining the flow path configured to inhibit build-up or adhesion of material on the surface may reduce or prevent a build-up of crystallised material on the injector mount downstream of a tip of the injector (which may eventually block the injector). That may increase a working life of the injector, maintain proper and efficient functioning of the injector and reduce servicing requirements for both the injector mount and the injector. The surface may be or comprise a low-friction surface. Additionally or alternatively, the surface may be or comprise a low-roughness surface. A low-friction surface may act to inhibit build-up of material on the surface by providing a low coefficient of friction, reducing an ability of materials to adhere to the surface (akin to the operation of a non-stick surface such as in cooking utensils). A low-roughness surface may act to inhibit build-up or adhesion of material on the surface by reducing a surface area and reducing a number and / or size of surface features with which materials can mechanically engage, reducing an ability of materials to adhere to the surface. The low-friction surface may be or comprise a low-friction coating. The low-friction coating may comprise a fluoropolymer coating. The fluoropolymer coating may be or comprise one or more of PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene propylene) and PFA (perfluoroalkoxy alkane). The low-friction surface may comprise a coefficient of friction of substantially 0.2 or lower. The low-roughness surface may comprise a surface roughness (Ra) of substantially 1,0pm or lower, or substantially 0.8pm or lower, or substantially 0.5pm or lower. The low-roughness surface may be or comprise a polished surface. The low-roughness surface may be or comprise a ceramic coating. The ceramic coating may be or comprise silicon carbide. The main body may comprise a flange for engaging the vehicle exhaust pipe. A surface of the flange may be configured to inhibit build-up or adhesion of material on the flange surface. The flange surface may be or comprise a low-friction surface and / or a low-roughness surface, for example a low-friction coating or a polished surface. That may further inhibit or prevent any build-up of material on the flange of the injector mount which could prevent fluid from the injector being injected into the vehicle exhaust pipe. Although the surface of the flange is not normally directly exposed to the flow of fluid from the injector, any exposed part of the surface of the flange which is not in contact with the vehicle exhaust pipe in use (i.e., when the injector mount is secured to the vehicle exhaust pipe) may provide a surface on which material can build-up to eventually block the injector. The low-roughness surface of the flange may comprise a surface roughness of substantially 1.0pm or lower, orsubstantially 0.8 pm or lower, or substantially 0.5pm or lower. The surface of the part of the internal channel defining the flow path may be arranged at an angle relative to a longitudinal axis of the internal channel, such that a cross-sectional size (for example, area) of the channel increases closer to the vehicle exhaust pipe. Arranging the surface at an angle may reduce or prevent fluid from the injector being injected directly onto the surface (which in use will likely be at a high temperature). That may further assist in reducing or preventing build-up of material on the surface. The surface of the part of the internal channel defining the flow path may be arranged at an angle of between substantially 35° and substantially 55° relative to the longitudinal axis of the internal channel. The surface may be arranged at an angle of approximately 45° relative to the longitudinal axis of the internal channel. A larger angle provides an increased surface area of the internal channel, for a given flow path length. Arranging the surface at an angle of between substantially 35° and substantially 55°, and preferably at an angle of approximately 45°, may reduce or prevent build-up of material by providing an optimal compromise between reducing fluid being injected directly onto the surface, and reducing a surface area of the part of the internal channel defining the flow path on which build-up can occur. The part of the internal channel defining the flow path may comprise a substantially frustoconical or frustopyramidal shape (a truncated cone shape or truncated pyramid shape). The part of the internal channel defining the flow path may comprise a width or diameter of between substantially 10mm and substantially 15mm, or approximately 10.5mm, adjacent a tip of the injector. The part of the internal channel defining the flow path may comprise a length of substantially 2mm or lower, or approximately 1.6mm. The part of the internal channel defining the flow path may comprise a clearance of substantially 0.25mm or lower, or substantially 0.2mm or lower, or approximately 0.1mm adjacent the tip of the injector. Minimising a clearance of the internal channel adjacent the injector tip may in turn reduce a surface area of the part of the internal channel defining the flow path. That may inhibit or prevent build-up of material on the surface, by reducing or minimising an available surface area for material to build up on. A surface of the part of the internal channel defining the flow path may comprise a surface area of substantially 200mm2 or lower, or substantially 150mm2 or lower, or substantially 100mm2 or lower, or substantially 75mm2 or lower, or approximately 62mm2. The internal channel may be configured to receive at least a part of the injector to support the injector in use. The internal channel may be configured to receive at least a part of a nozzle of the injector in use. The main body may be configured to support the injector in use such that a tip of the injector is set back substantially 5mm or less, or substantially 2mm or less, or approximately 1.6mm, from a surface of the main body configured to contact the vehicle exhaust pipe in use, for example the flange surface. Setting the tip of the injector back from the flange surface (and therefore from the vehicle exhaust pipe) may avoid directly exposing the tip of the injector to the high temperatures of the exhaust gases and the vehicle exhaust system, which may cause crystallization of fluid from or within the injector. However, setting the tip of the injector back from the vehicle exhaust pipe may also provide a surface downstream of the tip of the injector on which material can build up. Setting the tip of the injector back substantially 5mm or less, or substantially 2mm or less, or approximately 1.6mm, may provide an optimal balance that inhibits or prevents fluid crystallizing within the injector due to high temperatures whilst minimizing a surface area downstream of the tip of the injector. Setting the injector back such an optimal distance, in addition to the surface of the part of the internal channel defining the flow path being configured 5 to inhibit build-up of material on the surface, may significantly reduce build-up of material on the surface, allowing the injector to operate more efficiently and effectively over a longer time period before requiring servicing. The injector mount may be or comprise a unitary structure. The unitary structure may be formed from an aluminium alloy. The aluminium alloy may be or comprise an LM6 aluminium alloy. The injector mount comprising a unitary structure may enable the injector mount to act as an effective heat sink by providing a continuous thermal pathway through the injector mount (particularly when formed from an aluminium alloy, due to the high thermal conductivity of aluminium alloys). The unitary structure of the injector mount may also reduce cost and complexity of manufacturing the injector mount. The injector mount may efficiently conduct heat from the exhaust gases and the vehicle exhaust system through the injector mount to a medium surrounding the injector mount (typically air). That may help to reduce a temperature of the injector mount, the injector and the fluid. That may act to both prevent outright failure of the injector due to experiencing excessive temperature in use, and prevent or reduce crystallization of material which may then build-up on the surface of the internal channel and / or the injector itself. That in turn may enable the the injector to be positioned closer to the vehicle exhaust pipe when supported by the injector mount in use without experiencing excessive temperature. A decreased distance between a tip of the injector and the vehicle exhaust pipe may reduce a surface area (of the part of the internal channel defining the flow path) downstream of the injector tip. Reducing a surface area on which build-up of material can occur may reduce a risk of the injector becoming blocked or rendered inoperable. Reducing a distance between the tip of the injector and the vehicle exhaust pipe, and a surface area of the flow path, may also reduce an overall mass of the injector mount which may improve mechanical performance and longevity of the injector mount (for example, by reducing stress experienced due to mechanical vibration in use). Minimizing a surface area of the part of the internal channel defining the flow path, in addition to the surface of the part of the internal channel defining the flow path being configured to inhibit build-up of material on the surface, may significantly reduce build-up of material on the surface, allowing the injector to operate more efficiently and effectively over a longer time period before requiring servicing. The injector mount being formed from an aluminium alloy may also reduce a mass of the injector mount (for example, compared to using steel). That may increase reliability of the injector mount by reducing stress experienced by the injector mount due to mechanical vibration in use and may also reduce stress on a mounting portion of the vehicle exhaust pipe. The injector mount may also be easily die-cast. The high silicon content of a LM6 aluminium alloy may also provide good corrosion resistance for use in a high temperature environment such as a vehicle exhaust system whilst improving ease of machining the injector mount. The injector mount may comprise one or more fins extending from the main body. That may provide the injector mount with an increased surface area to improve dissipation of heat from the exhaust gases and the vehicle exhaust system. The injector mount may further comprise a resilient clip to secure the injector to the mount. That may provide a simple and convenient mechanism for the injector to be removed from and replaced into the injector mount when required (for example, during servicing). The resilient clip may or comprise a retaining ring or circlip. That may enable the injector to be releasably secured to the injector mount using a single, commonly available component. That may reduce a cost and complexity of manufacturing and servicing the injector and injector mount. Alternatively, the resilient clip may be integral to the injector mount. The injector mount may comprise a sleeve portion extending from the main body. The sleeve portion may be configured to receive and / or at least partially surround the injector in use. A recess or aperture may be provided on the sleeve portion. The recess or aperture may be configured to receive the clip. The sleeve portion may assist proper location of the injector in the injector mount and restrict movement of the injector relative to the injector mount once mounted. The sleeve portion may also provide a convenient location for positioning the clip, which is easily accessible when required (for example, by a maintenance operative during servicing). The sleeve portion may comprise a partially annular or arc-shaped cross-section. The recess or aperture may be substantially arc-shaped and configured to receive a circlip. That may provide a simple and convenient mechanism for releasably securing the injector to the injector mount, utilising a single, commonly available component. That may reduce a cost and complexity of manufacturing and servicing the injector and the injector mount. According to a second aspect, there is provided an injector mount for securing, to a vehicle exhaust pipe, an injector for injecting a fluid into the vehicle exhaust pipe. The mount may comprise a main body configured to support the injector in use. The mount may further comprise an aperture or recess. The aperture or recess may be configured to receive a clip to secure the injector in position on the mount. The injector mount of the second aspect may comprise one or more features of the injector mount of the first aspect, and vice versa. According to a third aspect, there is provided an injector unit for a vehicle exhaust system. The injector unit may comprise an injector mount. The injector mount may be or comprise the injector mount of the first aspect or of the second aspect. The injector unit may further comprise an injector for injecting a fluid into an exhaust pipe of the vehicle exhaust system. The injector mount may be configured to secure the injector to the vehicle exhaust pipe. Features which are described in the context of separate aspects and embodiments of the invention may be used together and / or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable sub-combination. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the invention will now be described by way of example only with reference to the following drawings in which: FIGs. 1A and IB show an injector mount for securing an injector to a vehicle exhaust pipe, according to an embodiment of the present invention; FIGs. 2A and 2B show cross-sectional views of the injector mount shown in FIGs. 1A and IB respectively without and with an injector mounted in the injector mount; and FIG. 3 shows a view of the injector mount from a bottom end of the injector mount configured to engage the vehicle exhaust pipe in use, showing a low-friction surface of a flow path portion of the injector mount and a polished surface of a flange of the injector mount. Like reference numerals in different Figures may represent like elements. DETAILED DESCRIPTION Figures 1A and IB show an injector mount 100 for securing, to a vehicle exhaust pipe, an injector for injecting a fluid into the vehicle exhaust pipe, according to an embodiment of the present invention. Figures 2A and 2B show the injector mount 100 in more detail. Figure 2A shows a cross-sectional view of the injector mount 100 alone, while Figure 2B shows a cross-sectional view of the injector mount 100 with an injector 150 engaged with the injector mount 100. In the embodiment shown, the injector mount 100 is for securing an injector 150 configured to inject a selective catalytic reduction (SCR) fluid such as AdBlue® or Urea into the vehicle exhaust pipe to reduce emissions of nitrogen oxides (NOx), although that is not essential and the injector 150 may alternatively be configured to inject any suitable fluid into the vehicle exhaust pipe. The injector mount 100 comprises a main body 105 configured to support the injector 150 in use. The main body 105 comprises an internal channel 108. A part 110 of the internal channel 108 defines a flow path for fluid from the injector to the exhaust pipe in use. A surface 110a of the part 110 of the internal channel 108 defining the flow path is configured to inhibit or prevent build-up of crystallized additive on the part of the internal channel 108 defining the flow path 108 (shown more clearly in Figure 3). As shown in Figure 2B, the main body 105 is configured to support the injector 105 such that at least a part of the injector 150 is received w ithin the internal channel 108 of the main body 105. In the embodiment shown, the internal channel 108 comprises a first portion 108a configured to receive a body 158 of the injector 150, a second portion 108b configured to receive a nozzle 152 of the injector 150, and a flow path portion 110 defining the flow path for fluid from the injector 150 to the exhaust pipe in use. The first portion 108a and the second portion 108b of the internal channel 108 comprise a complementary shape to at least a part of an external shape of the injector 150, although that is not essential. The first portion 108a has a larger width or diameter than the second portion 108b, such that a stepped portion or shoulder 115 is formed between the first portion 108a and the second portion 108b of the internal channel 108. The shoulder I 15 acts to support the body 158 of the injector 150 within the injector mount 100. The nozzle 152 is received within the second portion 108b of the internal channel 108 such that the flow path portion 110 of the internal channel 108 is located substantially entirely downstream of a nozzle tip 155 of the injector 150 (where the additive is injected from). In the embodiment shown, the nozzle 152 of the injector 108 extends substantially a full length of the second portion 108b of the internal channel 108 when the injector 150 is engaged with the injector mount 100. The shoulder 115 also acts to ensure the nozzle tip 155 is correctly positioned relative to the flow path portion 110 of the internal channel, by limiting a depth to which the nozzle 152 can be received within the second portion 108b of the internal channel 108. However, it will be appreciated the injector mount 100 may be configured to support the injector 150 in any suitable manner. In the embodiment shown, the main body 105 of the injector mount 100 comprises a generally cylindrical structure with a generally cylindrical internal channel 108 extending through the main body 105, although that is not essential. The body 158 and the nozzle 152 of the injector 150 each comprise a substantially cylindrical shape or circular cross-section, although that is not essential. The internal channel 108 and the nozzle 152 of the injector 150 may each comprise any suitable configuration or cross-sectional shape and need not have corresponding cross-sectional shapes. In the embodiment shown, the surface 110a of the flow path portion 110 of the internal channel 108 comprises a low-friction coating formed from or comprising PTFE (polytetrafluoroethylene). In the embodiment shown, the PTFE coating is provided over an anodised layer formed on the main body 105 at the flow path portion 110, although that is not essential. The PTFE coating comprises a coefficient of friction of between substantially 0.03 and substantially 0.2 (for example, measured in accordance with ISO 8295 or ASTM D1894). The PTFE coating comprises a surface roughness of approximately 0.8pm, although that may vary depending on surface finishing methodology. However, that is not essential, and the low-friction coating forming the surface 110a may be provided by alternative low-friction coatings, for example a low-friction coating comprising another fluoropolymer such as FEP (fluorinated ethylene propylene) or PFA (perfluoroalkoxy alkane). Fluoropolymer-based coatings typically have substantially similar coefficients of friction to those exhibited by PTFE. Alternatively, the surface 110a may be or comprise a ceramic coating, for example a coating comprising silicon carbide. Silicon carbide typically has a surface roughness (Ra) of approximately 0.8pm. A lower surface roughness may be achieved by adjusting coating process parameters to control a size of silicon carbide crystals in the coating. Alternatively, the surface 110a may not comprise a coating, and instead the surface 110a may comprise a polished or ground surface of the injector mount 100, thereby providing a low-roughness surface configured to inhibit or prevent build-up or adhesion of crystallized additive on the surface 110a. The polished surface 110a may be or comprise a mechanical surface finish of N4, corresponding to a surface roughness (Ra) of approximately 0.2pm. However, it will be appreciated the polished surface 110a may comprise a surface roughness of substantially 1.0pm or lower, for example may have a mechanical surface finish of N6 or finer, corresponding to a surface roughness of approximately 0.8pm or lower (see, for example, ISO 21920-2:2021 “Geometrical product specifications (GPS) - Surface Texture: Profile - Part 2: Terms, definitions, and surface texture parameters”, and / or the Engineers Blackbook). The main body 105 of the injector mount 100 further comprises a flange 112 for engaging the vehicle exhaust pipe, in order to secure the injector mount 100 to the vehicle exhaust pipe. A contact surface 112a of the flange 112 (that is, a surface of the flange 112 that contacts the vehicle exhaust pipe) comprises a polished surface (shown more clearly in Figure 3). In the embodiment shown, the contact surface 112a comprises an N4 finish corresponding to a surface roughness of approximately 0.64 pm or lower, although that is not essential. The polished contact surface 112a may have a lower surface roughness than unpolished surfaces of the injector mount 100. The contact surface 112a may alternatively comprise any suitable low-friction surface, for example a low-friction coating as described above with respect to the surface 110a of the flow path portion 110 of the internal channel 108. However, that is not essential, and the contact surface 112a may not comprise a polished or low-friction surface. The flange 112 comprises a generally circular shape with no engagement features defining a required orientation of the injector mount 100 on the vehicle exhaust pipe (for example, orientation tabs). That may improve ease of replacing and servicing the injector 150 and the injector mount 100. However, that is not essential, and the flange 112 may comprise such engagement features to define a required or desired orientation of the injector mount 100 when secured to the vehicle exhaust pipe. The surface 110a of the flow path portion 110 of the internal channel 108 is arranged at an oblique angle relative to a longitudinal axis A of the internal channel 108. As a result, the flow path portion 110 of the internal channel 108 comprises a substantially frustoconical shape (a truncated cone shape). It will be appreciated for an internal channel 108 comprising a different cross-sectional shape (for example, triangular, square, pentagonal, generally polygonal etc.) the angled surface 110a may result in the flow path portion 110 of the internal channel 108 comprising a substantially frustopyramidal shape (a truncated pyramidal shape). It will be appreciated the flow path portion 110 of the internal channel 108 may alternatively comprise any suitable shape or configuration. In the embodiment shown, the surface 110a is arranged at approximately 45°, but the surface 110a may alternatively be arranged at an angle of between 35° and 55° relative to the longitudinal axis A of the internal channel 108. However, that is not essential, and the surface 110a may not be angled relative to the longitudinal axis A of the internal channel 108. Adjacent the nozzle tip 155 where the flow path portion 110 of the internal channel 108 begins, a width or diameter of the internal channel 108 is approximately 10.5mm with a clearance around the nozzle tip 155 of approximately 0.1mm (for example, a tolerance ± 0.05mm). However, it 11 will be appreciated the width or diameter of the internal channel 108 adjacent the nozzle tip 155 may have any suitable dimension configured to receive an injector tip, for example between substantially 10mm and substantially 15mm. The internal channel 108 may also comprise a clearance around the nozzle tip 155 having any suitable dimension, for example substantially 0.25mm or lower. When the injector 150 is engaged with the injector mount 100 such that the injector 150 is supported by the main body 105, the nozzle tip 155 of the injector 150 is set back approximately 1.6mm from the contact surface 112a of the flange 112 which engages the vehicle exhaust pipe. However, the nozzle tip 155 of the injector 150 may be set back any suitable distance from the contact surface 112a, for example substantially 5mm or less, or substantially 2mm or less, or between substantially 1mm and substantially 2mm. The distance between the nozzle tip 155 of the injector 150 and the contact surface 112a of the flange 112 which engages the vehicle exhaust pipe defines the length of the flow path portion 110. Minimizing a clearance of the internal channel 108 around the nozzle tip 155 and reducing a length of the flow path portion 110 may reduce an area of the surface 110a available for crystallized additive to build up on. The injector mount 100 comprises a plurality of fins 118. The fins 118 are provided to increase a surface area of the injector mount 100 which is exposed to the surrounding air, enabling the injector mount 100 to efficiently and effectively dissipate heat in use, where the injector mount 100 and the injector 150 are exposed to the high temperatures of the exhaust gases and the vehicle exhaust system. The fins 118 extend substantially from the main body 105 in a generally radially outward direction. The fins 118 are oriented substantially perpendicular to the longitudinal axis A of the internal channel 108 (substantially horizontal in Figures 1A to 2B), although it will be appreciated the fins 118 may alternatively be oriented substantially parallel to the longitudinal axis A of the internal channel 108 (for example, substantially vertical) or at any other suitable angle. In the embodiment shown, the injector mount 100 comprises four fins 118, although that is not essential and any suitable number of fins 118 may alternatively be provided. In other arrangements, the injector mount 100 may not comprise any such fins. The injector mount 100 comprises a neck or sleeve portion 120 extending from the main body 105. In the embodiment shown, the sleeve portion 120 comprises a partially annular or arc-shaped cross-section which extends in a direction substantially parallel to the longitudinal axis A of the internal channel 108. The sleeve portion 120 defines a passageway through which the injector 150 can be passed to bring the injector 150 into engagement with the main body 105. The sleeve portion 120 may therefore assist in properly aligning the injector 150 with the main body 105 during installation. Once the injector 150 is engaged with the main body 105, the sleeve portion 120 at least partially encloses or surrounds the injector 150. That may restrict movement of the injector 150 relative to the injector mount 100 in use and may also protect the injector 150 from mechanical damage. In the embodiment shown, the injector 150 is press-fitted into the injector mount 100 forming an interference or friction fit to assist retaining of the injector 150 in the injector mount 100, although that is not essential. In the embodiment shown, the sleeve portion 120 comprises a channel 122 separating the ends of the partially annular or arc-shaped cross-section. The channel 122 extends from a distal end of the sleeve portion 120 (relative to the main body 105) substantially along an axial length of the sleeve portion 120. As shown in Figure 2B, in the embodiment shown the injector 150 comprises an electrical connection point 160 that extends radially outward of the body 158 of the injector 150. The channel 122 therefore provides a space through which an electrical connection point 160 of the injector 150 can travel such that the injector 150 can be brought into proper engagement with the main body 105, without the electrical connection point 160 obstructing movement of the injector 150 into the injector mount 100. The channel 122 also allows the electrical connection point 160 to be exposed to the surrounding air in use rather than enclosed by the sleeve portion 120. Having a part of the injector 150 (in this case, the electrical connection point 160) exposed to the surrounding air in use may improve cooling by having air flow over the injector 150. However, it will be appreciated the sleeve portion 120 may not comprise a channel 122, for example depending on the exact construction of the injector 150. The sleeve portion 120 also comprises an aperture or cutout 124. The cutout 124 in the sleeve portion 120 is arranged to receive a clip (not shown) which engages the injector 150 to secure the injector 150 to the injector mount 100. In the embodiment shown, the cutout 124 extends in a generally circumferential direction around the partially annular shape of the sleeve portion 120. The cutout 124 comprises a first cutout portion 124a and a second cutout portion 124b substantially aligned with one another around a circumference of the sleeve portion 120 spatially separated from one another by a solid part of the sleeve portion 120. A circlip or sprung retaining ring may be placed over the sleeve portion 120 such that the circlip extends through the cutout 124 to engage the injector 150 located within the sleeve portion 120. Tn the embodiment shown, the circlip extends through the cutout 124 and secures the injector 150 to the injector mount 100 by engaging a recess 162 formed in an external surface of the body 158 of the injector 150. The recess 162 is substantially aligned with the cutout 124 when the injector 150 is engaged with and received within the injector mount 100 to allow the retaining ring to pass through the cutout 124 and be received within the recess 162 of the injector 150. The retaining ring may be removed by applying a force to separate the free ends of the retaining ring such that the ring can be 13 disengaged from the recess 162 and the cutout 124 and removed from the sleeve portion 120, thereby allowing the injector 150 to be removed from the injector mount 100 when desired. However, that is not essential, and it will be appreciated the injector 150 may be secured to the 5 injector mount 100 via any suitable mechanism. For example, the injector mount 100 (for example, the sleeve portion 120) or the injector 150 (for example, the body 158) may comprise an integral resilient clip to secure and release the injector 150 to and from the injector mount 100. The integral resilient clip may be similar to or comprise a snap fit connection. 10 The injector mount 100 comprises a unitary structure, with all parts of the injector mount 100 forming an integral part of the same body. However, that is not essential, and the injector mount 100 may comprise one or more separate components which are mechanically connected to one another in use (for example, using one or more fasteners such as screws, bolts or clips). 15 In the embodiment shown, the injector mount 100 is formed from LM6 aluminium alloy, the composition of which is shown in Table 1 below: Alloying element Weight % Aluminium Remainder Magnesium 0.1 Copper 0.1 Iron (max) 0.6 Lead (max) 0.1 Tin (max) 0.05 Nickel (max) 0.1 Zinc 0.1 Silicon 10.0 to 13.0 Titanium (max) 0.2 Manganese (max) 0.5 Table 1 Composition of LM6 Aluminium Alloy 20 The high silicon content of the LM6 aluminium alloy may provide good corrosion resistance and ease of machining (for example, to provide the polished surface 112a of the flange 112), while the use of an aluminium alloy may allow the unitary structure of the injector mount 100 to be easily die-cast with minimal machine finish requirements. The use of aluminium alloy for the injector mount 100 may also reduce a mass of the injector mount (for example, relative to the 25 same structure formed from a different material such as a steel). The high thermal conductivity of aluminium alloys may also enable the injector mount 100 to efficiently dissipate heat from the hot exhaust gases and the vehicle exhaust system, to ensure the injector 150 supported by the injector mount 100 and the fluid injected by the injector 150 are not exposed to excessively high temperatures prior to entering the vehicle exhaust pipe (which may result in crystallization of a solid from the fluid, which can in turn build up on the injector and injector mount to block the injector or render the injector inoperable). However, it will be appreciated the injector mount 100 may alternatively be manufactured from a different metal or metal alloy, for example another aluminium alloy grade or a steel such as stainless steel. From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of injector mounts, in particular injector mounts for selective catalytic reduction (SCR) injectors, and which may be used instead of, or in addition to, features already described herein. Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom. For the sake of completeness, it is also stated that the term “comprising” does not exclude other elements or steps, the term “a” or “an” does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.

Claims

1. An injector mount for securing, to a vehicle exhaust pipe, an injector for injecting a fluid into the vehicle exhaust pipe, the mount comprising:a main body configured to support the injector in use, the main body comprising an internal channel, a part of the internal channel defining a flow path for fluid from the injector to the exhaust pipe in use;wherein a surface of the part of the internal channel defining the flow path is configured to inhibit build-up of material on the surface.

2. The injector mount of claim 1, wherein the surface comprises:i) a low-friction surface; and / orii) a low-roughness surface.

3. The injector mount of claim 2 part i), wherein the low-friction surface comprises a low-friction coating.

4. The injector mount of claim 3, wherein the low-friction coating comprises a fluoropolymer, and optionally wherein the low-friction coating comprises PTFE.

5. The injector mount of claim 1 or of claim 2, wherein the surface comprises a ceramic coating, and optionally wherein the ceramic coating comprises silicon carbide.

6. The injector mount of claim 2 part ii), wherein the low-roughness surface comprises a polished surface.

7. The injector mount of claim 2 part ii) or claim 6, wherein the low-roughness surface comprises a surface roughness of substantially 1.0pm or lower, optionally substantially 0.8pm or lower.

8. The injector mount of any preceding claim, wherein the main body comprises a flange for engaging the vehicle exhaust pipe, wherein the flange comprises a polished surface.

9. The injector mount of claim 8, wherein the polished surface comprises a surface roughness of approximately 0.8 pm or lower.

10. The injector mount of any preceding claim, wherein the surface of the part of the internal channel defining the flow path is arranged at an angle relative to a longitudinal axis of the16 internal channel such that a cross-sectional size of the flow path increases closer to the vehicle exhaust pipe.

11. The injector mount of claim 10, wherein the surface of the part of the internal channel defining the flow path is arranged at an angle of between substantially 35° and substantially 55° relative to the longitudinal axis of the internal channel, and optionally is arranged at an angle of approximately 45° relative to the longitudinal axis of the internal channel.

12. The injector mount of claim 10 or of claim 11, wherein the part of the internal channel defining the flow path comprises a substantially frustoconical shape.

13. The injector mount of any preceding claim, wherein the part of the internal channel defining the flow path comprises a width or diameter of substantially 15mm or lower adjacent a tip of the injector, and optionally approximately 10.5mm adjacent a tip of the injector14. The injector mount of any preceding claim, wherein a surface of the part of the internal channel defining the flow path comprises a surface area of substantially 200mm2 or lower.

15. The injector mount of any preceding claim, wherein the internal channel is configured to receive at least a part of the injector to support the injector in use.

16. The injector mount of any preceding claim, wherein the main body is configured to support the injector in use such that a tip of the injector is set back substantially 5mm or less from a surface of the main body configured to contact the vehicle exhaust pipe in use, optionally substantially 2mm or less, and further optionally approximately 1.6mm.

17. The injector mount of any preceding claim, wherein:i) the mount comprises a unitary structure; and / orii) the mount is formed from an aluminium alloy, optionally wherein the aluminium alloy comprises LM6 aluminium alloy.

18. The injector mount of claim 17, further comprising one or more fins extending from the main body.

19. The injector mount of any preceding claim, further comprising a resilient clip to secure the injector in position on the mount.

20. The injector mount of claim 19, wherein:the mount comprises a sleeve portion extending from the main body, the sleeve portion configured to at least partially surround the injector in use; anda recess or aperture configured to receive the clip is provided on the sleeve portion.5 21. The injector mount of claim 20, wherein:the sleeve portion comprises a substantially arc-shaped cross-section; andthe recess or aperture is substantially arc-shaped and configured to receive a circlip.

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