Roll cage

Abstract

Aspects and embodiments of the invention relate to an internal roll cage 10 for a vehicle, the internal roll cage comprising: a front canopy 12A comprising A-pillars 14A and a front roof cross-member

Description

TECHNICAL FIELD The present disclosure relates to an internal roll cage for a vehicle. The present disclosure also relates to a vehicle including an internal roll cage and a method of manufacturing an internal roll cage. BACKGROUND A roll cage is a structure which forms a canopy over the passenger compartment of certain vehicles in order to protect the vehicle occupants from being injured in the event of a rollover situation. For example, roll cages are commonly used in racing vehicles, off-road vehicles, ATVs, and sport utility vehicles for enhanced occupant protection. Typically, a roll cage is constructed as a welded tube structure which is assembled separately before being bolted or welded in place on the vehicle. However, in some instances, the assembled roll cage can interfere with the correct placement of other vehicle structures or components during and after installation. This can restrict the use or ideal placement of certain vehicle components or accessories and could complicate the vehicle assembly process. The present disclosure aims to provide an improved internal roll cage. SUMMARY OF THE INVENTION It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. Aspects and embodiments of the invention provide an internal roll cage, a method of manufacturing an internal roll cage, and a vehicle as claimed in the appended claims. Throughout the summary of the invention, description and claims the terms front, rear, left, right, upper and lower are defined with reference to their normal use in the description of a forward facing upright standing vehicle. It follows that features of the invention are described in relation to a vehicle such that, for example, front features are those closer to the front of the vehicle than rear features and upper features are those closer to the top of the vehicle than lower features. As used herein, the term “internal roll cage” refers to a roll cage which is located inside the outer shell of the vehicle. This is in contrast with an “external roll cage” which is configured for attachment to the vehicle outside, or predominantly outside, of the outer shell. According to an aspect of the invention there is provided an internal roll cage for a vehicle. The internal roll cage comprises a front canopy comprising A-pillars and a front roof crossmember extending between the A-pillars above a windshield area of the roll cage. Each A-pillar comprises a front strut and a front brace positioned rearwards of the front strut. The internal roll cage also comprises a dash bar extending between the A-pillars below the windshield area. The dash bar is removably coupled to the front strut of each A-pillar by a dash bar coupling. When the internal roll cage is in place inside a vehicle, the dash bar being removably coupled to the A-pillars allows auxiliary components proximal the dash bar (e.g. a HVAC system and / or a wiper mechanism) to be installed and / or accessed for maintenance by removing the dash bar. This differs from a typical roll cage arrangement in which the dash bar is welded (i.e. fixedly coupled) to the A-pillars. In addition, the dash bar being removably coupled to the front struts, as opposed to the front braces, enables the dash bar to be positioned further forward in relation to the driver to maximise cabin space. Optionally, the dash bar coupling comprises dash bar mounts fixed in relation to the front struts. Such dash bar mounts facilitate coupling of the dash bar to the A-pillars. Optionally, the dash bar coupling further comprises: a first coupling formation at a first end of the dash bar, which is configured to engage a first dash bar mount of a first front strut, and a second coupling formation at a second end of the dash bar, which is configured to engage a second dash bar mount of a second front strut. Such coupling formations facilitate coupling of the dash bar to the A-pillars. Optionally, the first coupling formation and the first dash bar mount are configured to form a first overlap joint, and wherein the second coupling formation and the second dash bar mount are configured to form a second overlap joint. It will be understood that the overlap joints, which comprise abutment surfaces on the dash bar and the dash bar mounts, provide an increased contact area between the dash bar and the dash bar mounts. This facilitates a secure coupling. It will also be understood that the overlap joints inhibit rotation of the dash bar relative to the dash bar mounts, which facilitates correct orientation of the dash bar relative to the A-pillars. This is particularly beneficial in embodiments where the dash bar is shaped (e.g. bent) to extend around one or more dashboard components (e.g., a HVAC system or a wiper mechanism), and / or in embodiments where the dash bar includes one or more brackets for mounting dashboard components. Optionally, each overlap joint is arranged such that an overlap surface of the first and second dash bar mounts on the first and second front struts faces rearwards and an overlap surface of the first and second coupling formations at the ends of the dash bar faces forwards. It will be understood that the overlap joints being arranged such that an overlap surface of the respective dash bar mount faces rearwards and an overlap surface of the respective coupling formation faces forwards means that the dash bar can be installed from behind the A-pillars in a forward direction or removed from the A-pillars in a rearward direction. The area rearward of the dash bar / A-pillars (e.g. a driver / passenger seating area of the vehicle) is typically an open space, whereas the areas in front, above and below the dash bar typically include obstructions such as bulkheads, steering columns, windshields etc. Therefore, this configuration of the overlap joints facilitates easier installation or removal of the dash bar when the roll cage is in place on a vehicle. Optionally, the first coupling formation and the first dash bar mount comprise complementary apertures for receiving a releasable fastener, and / or the second coupling formation and the second dash bar mount comprise complementary apertures for receiving a releasable fastener. Such complementary apertures for receiving a releasable fastener (e.g. a bolt, screw, pin or the like) provide a simple means to removably couple the dash bar to the dash bar mounts. It will be understood that suitable releasable fasteners are widely available. Optionally, the dash bar comprises a tubular member and wherein the first and second coupling formations are welded to the tubular member. Welding the coupling formations to the tubular member provides a secure and lightweight fixed attachment. Optionally, the dash bar mounts are welded to the front struts. Welding the dash bar mounts to the respective A-pillars provides a secure and lightweight fixed attachment. Optionally, the dash bar is non-linear. This can enable the dash bar to be shaped to extend around other internal components of a vehicle to which the roll cage is mounted during use, such as components of the HVAC system or wiper mechanism, without compromising the position of those components of the fixation point of the dash bar to the front struts. Optionally, the dash bar comprises a concave portion positioned along its length, the concave portion extending rearwards. With this arrangement, the concave portion can be shaped to accommodate other internal components of the vehicle while allowing the regions of the dash bar on either side of the concave portion, and the front struts, to be positioned further forwards. This can further increase the space available to occupants within the passenger compartment. Optionally, the dash bar comprises a lateral mid-point, and wherein the dash bar is asymmetrical about the lateral mid-point. In embodiments where the dash bar is shaped (e.g. bent) to extend around one or more dashboard components (e.g., a HVAC system or a wiper mechanism), the dash bar being asymmetrical about the lateral mid-point facilitates correct orientation of the dash bar relative to the A-pillars. This is particularly beneficial in embodiments where the dash bar includes one or more brackets for supporting one or more dashboard components, since correct orientation of the dash bar ensures a correct positioning of the bracket(s). Optionally, the dash bar comprises at least one bracket, optionally an upwardly facing bracket, for supporting at least one dashboard component of a vehicle. In this way, the dash bar provides an additional function of supporting one or more dashboard components, as well as strengthening the roll cage. Optionally, the at least one bracket comprises a pair of upwardly facing brackets. Having a pair of upwardly facing brackets allows multiple dashboard components (e.g. parts of a HVAC system and wiper mechanism) to be supported by the dash bar. Furthermore, dashboard components are typically mounted above the dash bar, and so the brackets being upwardly facing facilitates correct positioning of the dashboard components. Optionally, the front strut and front brace both extend from the front roof cross-member to a chassis mounting point at a base of the A-pillar. Such an arrangement has been found to provide good structural support to the roll cage. Optionally, each A-pillar further comprises a webbing extending between the front strut and the front brace. Such an arrangement has been found to provide good structural support to the roll cage. Such an arrangement has been found to provide good structural support to the roll cage. In addition, the dash bar being removably coupled to the front struts, as opposed to the front braces, enables the dash bar to be positioned further forward in relation to the driver to maximise cabin space. Optionally, the roll cage further comprises a rear canopy joined to the front canopy by one or more roof bars. Such an arrangement has been found to provide good structural support to the roll cage. According to an aspect of the invention there is provided a vehicle comprising an internal roll cage as disclosed herein. Such a vehicle benefits from the advantages of the internal roll cage outlined above. According to an aspect of the invention there is provided a method of manufacturing an internal roll cage for a vehicle. The method comprises the steps of: forming a front canopy of the internal roll cage having a pair of A-pillars and a front roof cross-member extending laterally between the A-pillars above a windshield area of the internal roll cage, wherein each A-pillar comprises a front strut and a front brace positioned rearwards of the front strut; locating a dash bar between the A-pillars below the windshield area; and removably coupling the dash bar to the front strut of each A-pillar using a dash bar coupling. Removably coupling the dash bar to the A-pillars allows auxiliary components proximal the dash bar (e.g., a HVAC system or a wiper mechanism) to be installed and / or accessed for maintenance whilst the roll cage is in place on the vehicle chassis by removing the dash bar. This differs from atypical method of manufacturing a roll cage in which the dash bar is welded (i.e. fixedly coupled) to the A-pillars. Optionally, the step of locating the dash bar between the A-pillars below the windshield area comprises: providing dash bar mounts coupled to the front struts; and moving the dash bar to engage the dash bar mounts in order to form overlap joints between the dash bar and the dash bar mounts; optionally, wherein the step of moving the dash bar to engage the dash bar mounts comprises moving the dash bar laterally in a forward direction. It will be understood that the overlap joints, provide an increased contact area between the dash bar and the dash bar mounts. This facilitates a secure coupling. It will also be understood that the overlap joints inhibit rotation of the dash bar relative to the dash bar mounts, which facilitates correct orientation of the dash bar relative to the A-pillars. This is particularly beneficial in embodiments where the dash bar is shaped (e.g. bent) to extend around one or more dashboard components (e.g., a HVAC system or a wiper mechanism), and / or in embodiments where the dash bar includes one or more brackets for mounting dashboard components. It will be understood that the area rearward of the dash bar (e.g. a driver / passenger seating area of the vehicle) is typically on open space, whereas the areas in front, above and below the dash bar typically include obstructions such as bulkheads, steering columns, windshields etc. Therefore, moving the dash bar laterally in a forward direction to engage the dash bar mounts facilitates easier installation (and subsequent removal) of the dash bar when the roll cage is assembled on a vehicle. Optionally, the step of removably coupling the dash bar to the front struts comprises: providing complementary apertures in the dash bar and the dash bar mounts; locating releasable fasteners in the complementary apertures; and securing the releasable fasteners to removably couple the dash bar to the front struts. Such a method allows a widely available releasable fastener (e.g. a bolt, screw, pin or the like) to be used to removably coupled the dash bar to the dash bar mounts. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will now be described, by way of example only, with reference to the following figures in which: Figure 1 is a front top perspective view of a roll cage according to an embodiment of the invention; Figure 2 is a rear top perspective view of the roll cage of Figure 1; Figure 3 is an enlarged perspective view of A-pillars and a dash bar of the roll cage of Figures 1 and 2; Figure 4 is an enlarged perspective view of a dash bar mount of the roll cage of Figures 1 and 2; Figure 5 is an enlarged perspective view of an end of the dash bar of Figures 1 to 4; Figure 6 is an enlarged perspective view of an overlap joint of the roll cage of Figures 1 to 4; Figure 7 is a vehicle in accordance with an embodiment of the invention; and Figure 8 is a flowchart illustrating a method of manufacturing a roll cage in accordance with the invention. DETAILED DESCRIPTION Figures 1 and 2 show an internal roll cage 10 according to an embodiment of the invention. The roll cage 10 has a front canopy 12A, a centre canopy 12B and a rear canopy 12C which together form a protective cage over front and rear passenger compartments 19 and 21. The front canopy 12A includes A-pillars 14A and a front roof cross-member 16A extending between the upper ends of the A-Pillars 14A. Each A-pillar 14A extends between the front roof cross member 16A and a chassis mounting point 17 at a base of the A-pillar 14A by which the roll cage 10 is fixed to the vehicle chassis or subframe (not shown). The centre canopy 12B includes B-pillars 14B and a centre roof cross-member 16B extending between the upper ends of the B-pillars 14B. Each B-pillar 14B extends between the centre roof cross-member 16B and a chassis mounting point 17 at a base of the B-pillar 14B. The rear canopy 12C includes C-pillars 14C and a rear roof cross-member 16C extending between the upper ends of the C-pillars 14C. Each C-pillar 14C extends between the rear roof cross-member 16C and a chassis mounting point 17 at a base of the C-pillar 14C. A front door opening 18 is defined on each side of the roll cage 10 between the A-pillars 14A and the B-pillars 14B. The front door openings 18 provide a point of entry / exit from the front passenger compartment 19. Similarly, a rear door opening 20 is defined on each side of the roll cage 10 between the B-pillars 14B and the C-pillars 14C. The rear door openings 20 provide a point of entry / exit from the rear passenger compartment 21. It will be understood that the front, centre and rear canopies 12A, 12B, 12C provide the roll cage 10 with torsional stiffness and structural integrity in lateral and vertical directions. This helps to increase performance of the associated vehicle and serves to protect occupants within the front and rear passenger compartments 19, 21 when the roll cage 10 is subjected to lateral or vertical impacts (e.g. ground-up vertical impacts which travel through the suspension). The roll cage 10 also includes left and right front roof bars 22 extending longitudinally between the front and centre canopies 12A, 12B. The left and right front roof bars 22 define an upper extent of the front door openings 18. The roll cage 10 also includes left and right rear roof bars 28 extending longitudinally between the centre and rear canopies 12B, 12C. The left and right rear roof bars 28 define an upper extent of the rear door openings 20. It will be understood that the left front roof bars and the left rear roof bars may be formed from a single, continuous component or from discrete components which are fixed together either directly or indirectly via one or more intermediate components. Similarly, the right front roof bars and the right rear roof bars may be formed from a single, continuous component or from discrete components which are fixed together either directly or indirectly via one or more intermediate components. In the illustrated embodiment, the roll cage 10 also includes a pair of front roof braces 24 which extend from a central region of the centre roof cross-member 16B to the front roof crossmember 16A. The front roof braces 24 diverge from each other towards the front roof crossmember 16A. In alternative embodiments, a different arrangement of front roof braces 24 may be provided (e.g. a single front roof brace extending between centre regions of the front and centre roof cross-members 16A, 16B). It will be understood that the front roof braces 24 further enhance the structural integrity of the front and centre canopies. In the illustrated embodiment, the roll cage 10 also has a front brace support 26 which extends between the pair of front roof braces 24. This further enhances the structural integrity of the front roof braces 24. The front brace support 26 is a tapered block, but other suitable supports may be used (e.g. a tapered sheet / webbing or lateral strut). In the illustrated embodiment, the roll cage 10 also includes a rear roof brace 30 which extends from a central region of the centre roof cross-member 16B to a central region of the rear roof cross-member 16C. In alternative embodiments, a different rear roof brace arrangement may be provided (e.g. a pair of diverging rear roof braces similar to the front roof braces 24 described above). It will be understood that the rear roof brace 30 further enhances the structural integrity of the centre canopy 12B and the rear canopy 12C. In the illustrated embodiment, each A-pillar 14A has a front strut 32 and a front brace 34 positioned rearwards of the front strut 32. The front strut 32 and the front brace 34 both extend downwards between a region at, or close to, the end of the front roof cross-member 16A and the mounting point 17 at the base of the A-pillar. In this example, the front strut 32 has a substantially upright lower portion and an angled upper portion which slopes rearward from the lower portion towards the front roof cross-member 16A, while the front brace is substantially straight. It will be understood that the term “upright” means within approximately 30 degrees of vertical, preferably within 15 degrees of vertical. Each A-pillar 14A also includes a webbing 36 extending between the front strut 32 and the front brace 34 to add structural support to the A-pillar. The webbing 36 may have weight-saving apertures 38. In the illustrated embodiment, each B-pillar 14B has a B-pillar strut 40 extending downwards between a region at or close to the end of the centre roof cross-member 16B and the mounting point 17 at the base of the B-pillar. The B-pillar strut 40 has a substantially upright lower portion 40a and an angled upper portion 40b which slopes rearward from the lower portion towards the centre roof cross-member 16B. In this manner, the lower portion 40a is positioned forward of the centre roof cross-member 16B, thereby increasing the size of each rear door opening 20. This B-pillar configuration makes it easier for passengers to enter the rear compartment 21 and may also make it easier to manufacture or modify the interior of a vehicle after the roll cage 10 has been installed. Each B-pillar 14B may also have a B-pillar brace 42 which extends between the B-pillar strut 40 and the respective front roof bar 22. In the illustrated embodiment, each B-pillar 14B has a B-pillar brace 42 coupled to the respective B-pillar strut 40 proximal to a transition region 40c between the upright portion 40a and the angled portion 40b. This can increase the resistance of the B-pillar to vertical loads. In the illustrated embodiment, the B-pillar braces 42 are substantially coaxial with the upright portions 40a of the B-pillar struts 40. In this way, the B-pillar braces 42 and upright portions 40a of the B-pillar struts 40 define a substantially straight rear extent of the front door openings 18. It will be understood that the centre roof cross member 16B and each B-pillar strut 40 or each B-pillar brace 42 may be formed from a single, continuous component or from discrete components which are fixed together either directly or indirectly via one or more intermediate components. In the illustrated embodiment, the centre roof cross member 16B and each B-pillar strut 40 are formed from a single tube and each B-pillar brace is a separate tube welded to its respective B-pillar 40 strut and roof bar. In alternative embodiments, the B-pillars 14B have a different configuration. For example, the upright portion 40a and B-pillar brace 42 may be defined by a common component (e.g. a single tubular member), and the angled portions 40b may be a separate component which is attached (e.g. by welding) to the common component. In the illustrated embodiment, each C-pillar 14C is formed as a C-pillar strut 44 which is inseparably fixed in relation to the rear roof cross-member 16C (e.g. by welding, or by forming the C-pillar struts 44 and rear roof cross-member 16C as a continuous tubular member). In alternative embodiments, the C-pillar struts 44 are separably fixed to the rear roof crossmember 16C (e.g. via a releasable fastener). In the illustrated embodiment, the C-pillar struts 44 and the rear roof bars 28 are strengthened by C-pillar braces 46 which extend between the respective C-pillar struts 44 and rear roof bars 28. In a similar way, the rear roof cross-member 16C and the rear roof bars 28 are strengthened by left and right rear roof cross-member braces 48 which extend between the rear roof cross member 16C and the left and right rear roof bars 28. In the illustrated embodiment, the rear canopy is further supported by a rear brace structure 50, which extends backwards from the rear canopy 12C to inhibit longitudinal movement of the rear canopy 12C in a rearward direction. The rear brace structure 50 includes rear brace struts 51 which extend downwards from at or close to the end of the rear roof cross-member 16C to a chassis mounting point 17 which is rearward of the chassis mounting point 17 of the C-pillar. The rear brace structure further includes left and right rear cross braces 52, which together form a broadly X-shaped reinforcement to the rear brace structure 50. Each rear cross brace 52 extends from a base of the respective rear brace 51 to the rear roof crossmember 16C. The rear cross braces 52 bow inwards from their upper and lower ends towards a longitudinal centreline of the rear brace structure 50. The rear cross braces 52 are strengthened in the central region of the X-shape by a pair of rear cross brace supports 54 which each extend between the pair of rear cross braces 52. The rear cross brace supports 54 are tapered blocks, but other suitable supports may be used (e.g. tapered sheets / webbing or lateral tubes). The rear brace structure 50 may further include left and right rear crossmembers 56 which each extend between the respective rear brace 51 and rear cross brace 52, and left and right rear C-pillar braces 58 which extend between the respective C-pillar struts 44 and rear braces 51. These rear cross-members 56 and rear C-pillar braces 58 further strengthen the bracing arrangement at the rear of the roll cage 10. It will be understood that in alternative embodiments, a different bracing arrangement may be provided at the rear of the roll cage 10. For example, one or more of the C-pillar braces 46, rear roof cross-member braces 48, rear cross braces 52, rear cross brace supports 54, rear cross-members 56 and rear C-pillar braces 58 may be omitted or replaced by an alternative configuration. In the illustrated embodiment, the roll cage 10 also includes a central support 60 which extends downward from the middle region of the centre roof cross-member 16B to a central chassis mounting point 17 at a base of the central support 60. The central support 60 reinforces the centre canopy 12B against vertical loading. In the illustrated embodiment, the roll cage 10 also includes a dash bar 70 extending transversely between the A-piIlars 14A. The dash bar 70 defines a lower extent of a windshield area 72. An upper extent of the windshield area 72 is defined by the front roof cross-member 16A. Left and right extents of the windshield area 72 are defined by the A-piIlars 14A. Referring now to Figures 3 to 6, the dash bar 70 is removably coupled to the front struts 32 of the A-pillars 14A by a dash bar coupling 74. In this manner, the dash bar 70 can be coupled to the A-pillars 14A (as illustrated in Figure 3) or removed from the A-pillars 14A without causing damage to the dash bar 70 or A-pillars 14A. By coupling the dash bar 70 to the front struts 32 of the A-pillars 14A the space behind the dash bar 70 (i.e. space in the front cabin region 19) can be maximised. The dash bar coupling could have any suitable arrangement. In the illustrated embodiment, part of the dash bar coupling 74 is in the form of first and second dash bar mounts 76a, 76b which are fixed in relation to the respective A-pillars 14A (as illustrated in Figure 4). The other part of the dash bar coupling 74 is in the form of first and second coupling formations 78a, 78b provided at respective first and second ends 80a, 80b of the dash bar 70 (as illustrated in Figure 5). The first coupling formation 78a is configured to engage the first dash bar mount 76a. In particular, the first coupling formation 78a and the first dash bar mount 76a are configured to form a first overlap joint 82. Similarly, the second coupling formation 78b is configured to engage the second dash bar mount 76b. In particular, the second coupling formation 78b and the second dash bar mount 76b are configured to form a second overlap joint 82. It will be understood that the overlap joints 82 each include an overlap surface 84 on the respective dash bar mount 76a, 76b (as illustrated in Figure 4) and an overlap surface 86 on the respective coupling formation 78a, 78b (as illustrated in Figure 5). In order to form the overlap joints 82, the overlap surface 84 of the respective dash bar mount 76a, 76b is placed in abutment with the overlap surface 86 of the respective coupling formation 78a, 78b. In the illustrated embodiment, the overlap joints 82 each include complementary formations on the respective dash bar mount 76a, 76b and coupling formation 78a, 78b for resisting relative movement therebetween in a direction parallel to a longitudinal axis of the dash bar 70. In particular, each dash bar mount 76a, 76b has a recess 85 in its overlap surface 84 (as illustrated in Figure 4) and each coupling formation 78a, 78b has a projection 87 extending from its overlap surface 86 (as illustrated in Figure 5). The projection 87 is received within the recess 85 (as illustrated in Figure 6). In the illustrated embodiment, the recess 85 is a linear groove and the projection 87 is a linear projection. In alternative embodiments, a different shape of recess 85 and / or projection 87 is used (e.g. one or more circular recesses 85 and projections 87). In the illustrated embodiment, the recesses 85 are provided in the overlap surfaces 84 of the dash bar mounts 76a, 76b at a region proximal the respective A-pillar 14A. Accordingly, the projections 87 are provided extend from the overlap surfaces 86 of the coupling formations 78a, 78b at a distal end of the coupling formations 78a, 78b. In alternative embodiments, the recesses 85 and projections 87 are located at different points along the respective overlap surfaces 84, 86 (e.g. approximately halfway along the respective overlap surfaces 84, 86). As illustrated in Figures 4 to 6, the overlap surfaces 84 of the dash bar mounts 76a, 76b face rearwards and the overlap surfaces 86 of the coupling formations 78a, 78b face forwards. It will be understood that this means that the dash bar 70 can be installed from behind the A-pillars 14A in a forward direction, or removed from the A-pillars 14A in a rearward direction. The area rearward of the dash bar 70 (i.e. the front cabin region 19) is typically an open space, whereas the areas in front, above and below the dash bar 70 typically include obstructions such as bulkheads, steering columns, windshields etc. Therefore, this configuration of the overlap joints 82 facilitates easier installation or removal of the dash bar 70 when the roll cage 10 is in place on a vehicle. In the illustrated embodiment, the first coupling formation 78a and the first dash bar mount 76a have complementary apertures 88 for receiving a releasable fastener (not shown). Similarly, the second coupling formation 78b and the second dash bar mount 76b have complementary apertures 88 for receiving a releasable fastener (not shown). In the illustrated embodiment, there are two pairs of complementary apertures 88 at each of the overlap joints 82. In alternative embodiments, more or less than two pairs of complementary apertures 88 are provided at each overlap joint 82. It will be understood that in order to couple the dash bar 70 to the A-pillars 14A, releasable fasteners (e.g. bolts, screws, pins or the like) would be provided in each pair of complementary apertures 88 and would be fastened in place to secure the overlap joints 82 (e.g. fastened in place by a nut or by engaging complementary threads in one or more of the apertures 88). In some embodiments, the dash bar 70 is a tubular member and the first and second coupling formations 78a, 78b are welded to the tubular member 70 (i.e. at opposite ends of the tubular member 70). In such embodiments, the first and second coupling formations 78a, 78b may each include a skirt portion which is fitted inside the respective end of the tubular member 70 prior to welding. In alternative embodiments, the first and second coupling formations 78a, 78b are fixed in relation to the tubular member 70 via a different means (e.g. by releasable fasteners received in apertures through the tubular member 70 and a skirt portion of the coupling formations 78a, 78b, or by being integrally formed with the tubular member 70). In the illustrated embodiment, the dash bar mounts 76a, 76b are welded to the respective A-pillars 14A. In particular, the dash bar mounts 76a, 76b are welded to the A-pillar struts 32 of the A-pillars 14A. In alternative embodiments, the dash bar mounts 76a, 76b are otherwise fixed in relation to the respective A-pillars. For example, the dash bar mounts 76a, 76b may be integrally formed with the respective A-pillars 14A, or secured to the respective A-pillars 14A by releasable fasteners. In some embodiments, the dash bar 70 engages the dash bar mounts 76a, 76b in a different way to the overlap joint arrangement described above. For example, the dash bar mounts 76a, 76b may define part-circular seats (e.g. semi-circular seats) which are configured to receive the first and second ends 80a, 80b of the dash bar 70. In the illustrated embodiment, the dash bar 70 is non-linear and shaped (e.g. bent) to extend around one or more dashboard components of a vehicle which the dash bar 70 would otherwise obstruct. For example, the illustrated dash bar 70 is shaped to extend around a HVAC unit provided on a dashboard of a vehicle. In particular, the dash bar 70 includes a concave portion 90 positioned along its length. The concave portion extends rearwards and is arranged to be rearward of the first and second ends 80a, 80b of the dash bar 70. This allows the ends of the dash bar 70 to be installed as far forward as possible, without obstructing the HVAC unit. In the illustrated embodiment, the concave portion 90 is positioned approximately at the mid-point along the length of the dash bar 70. This enables the dash bar 70 to extend around a centrally located internal component such as an HVAC unit (not shown) positioned forward of the concave portion 90. However, it will be understood that the concave portion, or further concave portions, could be positioned at any point along the length of the dash bar 70 to accommodate other internal components of the vehicle. In some embodiments, the dash bar 70 is asymmetrical about its lateral mid-point. For example, the dash bar 70 may be shaped to extend around, and / or provide attachment points for, vehicle components (not shown) which are not symmetrically distributed on the dashboard. For example, the dash bar 70 may be shaped to extend around a steering column on one side of the vehicle. It will be understood that in such embodiments the dash bar 70 may be manufactured in “left hand drive” and “right hand drive” versions, since left hand drive vehicles may have a different arrangement of vehicle components to right hand drive vehicles. The dash bar 70 being removable from the A-pillars 14A is particularly useful in such applications, because it allows a common roll cage 10 to be used for both left and right hand drive vehicles, with only the dash bar 70 being changed for the different vehicles. In the illustrated embodiment, the dash bar 70 has a pair of upwardly facing brackets 92. The brackets 92 are configured to support at least one dashboard component of a vehicle (not shown). For example, the brackets 92 may support HVAC vent units or other dashboard components in the vicinity of the dash bar 70. In some examples, a first of the brackets 92 may be used to mount an instrument cluster on one side of the dash bar 70, and a second of the brackets 92 may be used as a mounting point for a structure of the dashboard on the other side of the dash bar 70. Referring now to Figure 7, a vehicle having a roll cage 10 as hereinbefore described is indicated schematically at 200. The outline of the roll cage 10 is shown but the rest of the roll cage is omitted from Figure 7, since it is internal to the vehicle 200 and is thus not visible from external view. It will be understood that the roll cage 10 is positioned within the vehicle 200 so that the front door openings 18 of the roll cage 10 are approximately in line with front doors 202 of the vehicle 200 and the rear door openings 20 are approximately in line with the rear doors 204 of the vehicle. Figure 8 illustrates an exemplary method of manufacturing the roll cage 10 according to the present invention. The method includes the following steps: at step 801, forming the front canopy 12A, the front canopy comprising the pair of A-pillars 14A and the front roof cross-member 16A extending laterally between the A-pillars above the windshield area 72 of the roll cage; at step 802, locating the dash bar 70 between the A-pillars 14A at a position below the windshield area 72; and at step 803, removably coupling the dash bar 70 to the A-pillars 14A using the dash bar coupling 74; for example, by engaging the dash bar mounts 76a, 76b on the respective A-pillars 14A with first and second coupling formations 78a, 78b at the ends 80a, 80b of the dash bar 70 to form first and second overlap joints and securing releasable fasteners in the complementary apertures 88 of the overlap joints 82. It will be appreciated that various changes and modifications can be made to the present disclosed examples without departing from the scope of the present application as defined by the appended claims. Whilst endeavouring in the foregoing specification to draw attention to those features believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon. Table 1 - Reference text for Figure 8 801 Form front canopy 802 Locate dash bar 803 Removably couple dash bar to A-pillars

Claims

1. An internal roll cage for a vehicle, the internal roll cage comprising:a front canopy comprising A-pillars and a front roof cross-member extending between the A-pillars above a windshield area of the roll cage, wherein each A-pillar comprises a front strut and a front brace positioned rearwards of the front strut; anda dash bar extending between the A-pillars below the windshield area, wherein the dash bar is removably coupled to the front strut of each A-pillar by a dash bar coupling.

2. The internal roll cage of claim 1, wherein the dash bar coupling comprises dash bar mounts fixed in relation to the front struts.

3. The internal roll cage of claim 2, wherein the dash bar coupling further comprises: a first coupling formation at a first end of the dash bar, which is configured to engage a first dash bar mount of a first front strut, anda second coupling formation at a second end of the dash bar, which is configured to engage a second dash bar mount of a second front strut.

4. The internal roll cage of claim 3, wherein the first coupling formation and the first dash bar mount are configured to form a first overlap joint, and wherein the second coupling formation and the second dash bar mount are configured to form a second overlap joint.

5. The internal roll cage of claim 4, wherein each overlap joint is arranged such that an overlap surface of the first and second dash bar mounts on the first and second front struts faces rearwards and an overlap surface of the first and second coupling formations at the ends of the dash bar faces forwards.

6. The internal roll cage of any of claims 3 to 5, wherein the first coupling formation and the first dash bar mount comprise complementary apertures for receiving a releasable fastener, and wherein the second coupling formation and the second dash bar mount comprise complementary apertures for receiving a releasable fastener.

7. The internal roll cage of any of claims 3 to 6, wherein the dash bar comprises a tubular member and wherein the first and second coupling formations are welded to the tubular member.

8. The internal roll cage of any preceding claim, wherein the dash bar comprises a concave portion positioned along its length, the concave portion extending rearwards.

9. The internal roll cage of any preceding claim, wherein the dash bar comprises a lateral mid-point, and wherein the dash bar is asymmetrical about the lateral mid-point.

10. The internal roll cage of any preceding claim, wherein the dash bar comprises at least one bracket, optionally an upwardly facing bracket, for supporting at least one dashboard component of a vehicle.

11. The internal roll cage of any preceding claim, wherein the front strut and front brace both extend from the front roof cross-member to a chassis mounting point at a base of the A-pillar.

12. The internal roll cage of any preceding claim, wherein the roll cage further comprises a rear canopy joined to the front canopy by one or more roof bars.

13. A vehicle comprising the internal roll cage of any preceding claim.

14. A method of manufacturing an internal roll cage for a vehicle, the method comprisingthe steps of:forming a front canopy of the internal roll cage having a pair of A-pillars and a front roof cross-member extending laterally between the A-pillars above a windshield area of the internal roll cage, wherein each A-pillar comprises a front strut and a front brace positioned rearwards of the front strut;locating a dash bar between the A-pillars below the windshield area; andremovably coupling the dash bar to the front strut of each A-pillar using a dash bar coupling.

15. The method of claim 14, wherein the step of locating the dash bar between the A-pillars below the windshield area comprises:providing dash bar mounts coupled to the front struts; andmoving the dash bar to engage the dash bar mounts in order to form overlap joints between the dash bar and the dash bar mounts;optionally, wherein the step of moving the dash bar to engage the dash bar mounts comprises moving the dash bar laterally in a forward direction.

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