Cylinder block and method of manufacture

Abstract

A cylinder block of an internal combustion engine (3, fig.1). The cylinder block (1, fig.1) has a cylinder bore 23-1 for receiving a piston. The cylinder block is comprised of an alloy having a therma

Description

TECHNICAL FIELD The present disclosure relates to a cylinder block, a machine tool and a method of manufacture. Aspects of the invention relate to a cylinder block; an internal combustion engine; a vehicle and a method of forming a cylinder block. BACKGROUND It is known to provide a thermal spray coating on a cylinder bore of an internal combustion engine. This approach may, for example, be used on an alloy cylinder block to provide an internal finish capable of withstanding thermal and mechanical operating loads. The thermal spray coating may, for example, be used in place of a sleeve or liner in the cylinder bore. Machining of a thermal sprayed cylinder bore may, however, be problematic for conventional tooling, such as a carbide or cubic boron nitride (CBN). The machining of the bi-metallic composition, i.e., the alloy and thermal spray coating of the cylinder block, may result in a relatively short tool life. High volume production facilities with low tool life will experience higher levels of loss production time due to more frequent tool changes and increased cost. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a cylinder block; an internal combustion engine; a vehicle; a grinding tool and a method of forming a cylinder block as claimed in the appended claims According to an aspect of the present invention there is provided a cylinder block of an internal combustion engine, the cylinder block having a cylinder bore for receiving a piston, wherein the cylinder block is composed of an alloy having a thermal spray coating disposed on an internal surface of the cylinder bore; wherein a first chamfer is formed in a first end region of the cylinder bore, the first chamfer forming a first taper in the thermal spray coating in a first direction away from the cylinder bore. The first chamfer may provide an improved finish in the first end region of the cylinder bore. The first chamfer may at least partially remove overspray of the thermal spray coating around the cylinder bore. The first chamfer reduces a thickness of the thermal spray coating in the first direction. The cylinder block is an alloy cylinder block having a thermal spray coating. The cylinder block may comprise or consist of a block casting of the alloy. The alloy may, for example, comprise an aluminium alloy. The thermal spray coating may provide thermal and / or mechanical properties for withstanding operational loads in the cylinder, for example caused by combustion of a fuel, or movement of a piston, within the cylinder during operation of the internal combustion engine. The thermal spray coating may, for example, be provided in place of a cylinder liner or sleeve. The first chamfer extends at least partway through the thermal spray coating. At least in certain embodiments, the first chamfer may extend completely through the thermal spray coating. The first chamfer may extend into the alloy portion of the cylinder block. The first chamfer may be formed through the thermal spray coating and into the alloy cylinder block. The first chamfer may comprise or consist of a substantially continuous taper formed in the thermal spray coating and the alloy. The cylinder bore comprises a central longitudinal axis. The first direction may be at least substantially parallel to or coincident with the central longitudinal axis. At least in certain embodiments, the first chamfer is formed by a grinding operation. The grinding operation may be performed to remove the thermal spray coating and the alloy forming the cylinder block. At least in certain embodiments, the grinding operation may remove the thermal spray coating and the alloy at the same time. The grinding operation may be performed using a grinding tool of the type described herein, for example. The grinding operation removes at least some of the thermal spray coating in the first end region to form the first chamfer. The grinding operation may also remove some of the alloy forming the cylinder block. The grinding operation may thereby form the first chamfer in the thermal spray coating and the cylinder block. The first taper may be a substantially constant taper. The first chamfer may comprise or consist of a substantially constant taper formed in the thermal spray coating and the alloy. The first taper may be inclined at a first angle to a central longitudinal axis of the cylinder bore. The first angle may be less than or equal to 45°. The first angle may be less than or equal to 35°. The first angle may be less than or equal to 25°. The first chamfer may extend at least partway through the thermal spray coating. A thickness of the thermal spray coating may be reduced in the first direction. The thickness of the thermal spray coating is measured in a radial direction of the cylinder bore. The radial direction may be substantially perpendicular to the central longitudinal axis of the cylinder bore. The thickness may decrease from a working thickness in the cylinder bore. The working thickness provides appropriate thermal and / or mechanical properties for combustion, and or piston movement, within the cylinder bore during operation of the internal combustion engine. The chamfer may remove the thermal spray coating, for example at an end of the cylinder bore. The chamfer may extend into the alloy forming the cylinder block. A second chamfer may be formed in a second end region of the cylinder bore. The second chamfer may form a second taper in the thermal spray coating. The second taper may be formed in a second direction away from the cylinder bore. The second direction may be at least substantially parallel to or coincident with the central longitudinal axis of the cylinder bore. The first and second directions may be opposite to each other. The first and second end regions may be disposed at opposing first and second ends of the cylinder bore. The cylinder bore may comprise a first end and a second end. The first end region may be disposed at the first end of the cylinder bore; and the second end region may be disposed at the second end of the cylinder bore. The cylinder block typically comprises a cylinder block face (head-deck face) configured to cooperate with a cylinder head. The first end of the cylinder bore may be disposed adjacent to the cylinder block face. The first chamfer may be formed at or proximal to the cylinder block face. Alternatively, the second end of the cylinder bore may be disposed adjacent to the cylinder block face. The second chamfer may be formed at or proximal to the cylinder block face. The cylinder block face may be configured to form a seal with a cylinder head. In use, a sealing membrane or a gasket may be disposed on the cylinder block face to form a seal between the cylinder block and the cylinder head. The first end region may be disposed at a top of the cylinder bore; and the second end region may be disposed at a bottom of the cylinder bore. Alternatively, the first end region may be disposed at a bottom of the cylinder bore; and the second end region may be disposed at a top of the cylinder bore. The second chamfer may be formed by a grinding operation. The grinding operation may be performed to remove the thermal spray coating and the alloy forming the cylinder block. The second taper may be a substantially constant taper. The second chamfer may comprise or consist of a substantially constant taper formed in the thermal spray coating and the alloy. The second taper may be inclined at a second angle to a central longitudinal axis of the cylinder bore. The second angle may be less than the first angle. The second angle may be less than or equal to 45°. The second angle may be less than or equal to 30°. The second angle may be less than or equal to 15°. According to an aspect of the present invention there is provided an internal combustion engine comprising a cylinder block as described herein. A cylinder head may be mounted to the cylinder block. According to an aspect of the present invention there is provided a vehicle comprising a cylinder block as described herein. The cylinder block may form part of an internal combustion engine provided in the vehicle. According to a further aspect of the present invention there is provided a method of forming a first end region of a cylinder bore, the cylinder bore being disposed in a cylinder block of an internal combustion engine and being configured to receive a piston, wherein the cylinder block is composed of an alloy and a thermal spray coating is disposed on an internal surface of the cylinder bore; wherein the method comprises forming a first chamfer in the first end region of the cylinder bore, the first chamfer comprising a first taper in the thermal spray coating in a first direction away from the cylinder bore. The method may comprise using a grinding tool to form the first chamfer in a first grinding operation. The thermal spray coating is applied to the cylinder block using an appropriate deposition technique. The first method may comprise using a grinding tool to form the first chamfer in a first grinding operation. The grinding tool may comprise a first grinding contact surface for forming the first chamfer. The first grinding contact surface may, for example, comprise a diamond coating operative to grind both the thermal spray coating and the alloy cylinder block. The method may comprise introducing at least a portion of the grinding tool into the cylinder bore. The method may comprise displacing the grinding tool in a direction substantially perpendicular to a rotational axis of the grinding tool to bring the grinding contact surface into contact with the thermal spray coating on the internal surface of the cylinder bore. The lateral displacement of the griding tool may help to reduce or avoid separating the thermal spray coating from the alloy forming the cylinder block. The grinding tool may be displaced along an orbital path to form the first chamfer. The method may comprise forming a second chamfer in a second end region of the cylinder bore. The second chamfer may comprise a second taper in the thermal spray coating in a second direction away from the cylinder bore. The grinding tool may comprise a second grinding contact surface for forming the second chamfer. The second grinding contact surface may comprise a diamond coating operative to grind both the thermal spray coating and the alloy cylinder block. The method may comprise using the grinding tool to form the second chamfer in a second grinding operation. 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 One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle comprising an internal combustion engine having a cylinder block in accordance with an embodiment of the present invention; Figure 2 shows a vertical sectional view through the cylinder block and cylinder head of the internal combustion engine shown in Figure 1; Figure 3 shows a vertical section through the cylinder block showing a grinding tool in a first position along a longitudinal axis to form a first end region of the cylinder bore; Figure 4 shows enlarged views of the upper and lower ends of the grinding tool in the first position shown in Figure 3; Figure 5 shows a vertical section through the cylinder block showing a grinding tool in a second position along a longitudinal axis to form a second end region of the cylinder bore; and Figure 6 shows enlarged views of the upper and lower ends of the grinding tool in the second position shown in Figure 5. DETAILED DESCRIPTION A cylinder block 1 of an internal combustion engine 3 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures. A method of forming the cylinder block 1 is also described herein. As shown schematically in Figure 1, the engine 3 in the present embodiment is disposed in a road vehicle 5. The engine 3 is operative to generate a torque to propel the vehicle 5. The vehicle 5 may be powered exclusively by the internal combustion engine 3. Alternatively, the vehicle 5 may be hybrid electric vehicle, for example a plug-in hybrid electric vehicle. The vehicle 5 in the present embodiment is an automobile. The vehicle 5 could be a utility vehicle or a sports utility vehicle, for example. It will be understood that the engine 3 may be installed in other types of vehicle. The engine 3 in the present embodiment is a spark ignition, reciprocating piston internal combustion engine. In a variant, the engine 3 may be a compression ignition reciprocating piston internal combustion engine. The cylinder block 1 comprises a plurality of cylinders 11-n. Byway of example, the cylinder block 1 may comprise three (3), four (4), six (6) or eight (8) of the cylinders 11-n. The engine 3 comprises a crankshaft (not shown) connected to a plurality of pistons 15. As shown schematically in Figure 2, the pistons 15-n are each associated with a respective one of the cylinders 11-n. The cylinders 11-n and the pistons 15 collectively form combustion chambers 17. A cylinder head 19 is fastened to the cylinder block 1. The cylinder block 1 is a bimetallic block comprising two or more metals. The cylinder block 1 comprises a block casting 21 formed by casting an aluminium alloy. Cylinder bores 23-n are formed in the block casting 21 to form the cylinders 11-n. The pistons 15 reciprocate within the cylinder bores 23-n formed in the cylinder block 1. The cylinder bores 23-n are machined to the appropriate dimensions. A cylinder liner 25-n is then disposed in each cylinder bore 23-n. In the present embodiment, the cylinder liners 25-n comprise a surface coating applied to an internal surface 27 of the cylinder bore 23-n. The surface coating is denoted generally by the reference numeral SC in Figure 4. The surface coating SC is a thermal spray coating applied using thermal spray coating techniques. The cylinder liner 25-n has mechanical properties which are different from those of the block casting 21. For example, the cylinder liner 25-n has a greater hardness than the block casting 21. The bimetallic block is difficult to machine because of the different mechanical properties of the block casting 21 and the cylinder liner 25-n which may cause a high wear rate of tools by the hard surface coating, and a build-up on the tool of the softer block casting material. The forming of a first one of the cylinders 11-n is described herein with reference to Figures 3 to 6. It will be understood that the same process is performed in respect of each of the cylinders 11-n. The first cylinder 11-1 has a central first longitudinal axis X1. A first sectional view of the first cylinder 11-1 along the first longitudinal axis X1 is shown in Figure 3. The first cylinder 11-1 has a first end region 33 and a second end region 35. In the present embodiment, the first end region 33 is formed at an upper end of the first cylinder 11; and the second end region 35 is formed at a lower end of the first cylinder 11-1. The first end region 33 is disposed adjacent to a cylinder block face 37 for cooperating with the cylinder head 19. An undercut 39 is formed in the block casting 21 below the second end region 35. The undercut 39 is annular and extends circumferentially below the first cylinder 11-1. The undercut 39 may be machined in the block casting 21. The first cylinder 11-1 comprises a first cylinder bore 23-1 formed in the block casting 21. After casting, a cubing operation is performed to prepare the block casting 21 for a rough (preliminary) machining operation. The first cylinder bore 23-1 may be formed in the block casting 21 during the cubing operation. A first profile P1 showing the shape of the block casting 21 afterthe cubing process is shown in Figure 4. The first cylinder bore 23-1 is machined to the appropriate dimensions. The cylinder liner 25-1 is a thermal spray coating and is applied to the internal surface 27 of the first cylinder bore 23-1. The thermal spray coating has a thickness of approximately 20 microns in the present embodiment. A second profile P2 showing the shape of the block casting 21 after application of the thermal spray coating is shown in Figure 4. A first chamfer 43 is formed in the first end region 33 of the first cylinder bore 23-1. The first chamber 43 is formed by a first grinding operation. The first chamfer 43 forms a first taper in the thermal spray coating in a first direction away from the first cylinder bore 23-1. The first taper 43 is inclined at a first angle to the first longitudinal axis X1 of the first cylinder bore 23-1. A thickness of the thermal spray coating is reduced in the first direction. The thickness of the thermal spray coating decreases from a working thickness in the first cylinder bore 23-1. The first angle is constant in the first taper 43. The first angle a1 is less than or equal to 45°. In the present embodiment, the first angle a1 is approximately 15°. The first chamfer 43 extends through the thermal spray coating forming the cylinder liner 25-1 and into the block casting 21. A third profile P3 showing the shape of the first chamfer 43 is shown in Figure 4. A second chamfer 45 is formed in the second end region 35 of the first cylinder bore 23-1. The second chamber 45 is formed by a second grinding operation. The second chamfer 45 forms a second taper in the thermal spray coating in a second direction away from the first cylinder bore 23-1. The second taper 45 is inclined at a second angle a2 to the first longitudinal axis X1 of the first cylinder bore 23-1. The second angle a2 is constant in the second taper 45. The second angle is less than or equal to 45°. In the present embodiment, the second angle a2 is approximately 30°. A thickness of the thermal spray coating is reduced in the second direction. The thickness of the thermal spray coating decreases from a working thickness in the first cylinder bore 23-1. The first chamfer 43 extends through the thermal spray coating forming the cylinder liner 25-1 and into the block casting 21. The first and second directions are opposite to each other. A fourth profile P4 showing the shape of the second chamfer 45 is shown in Figure 4. The formation of the first and second chamfers 43, 45 will now be described in more detail. In the present embodiment, a grinding tool 51 is used to form both the first and second chamfers 43, 45. The first and second chamfers 43, 45 are formed by first and second grinding operations. The first and second grinding operations may be performed in any order and the present invention is not restricted to a particular order or sequence of forming the first and second chamfers 43, 45. The grinding tool 51 comprises a first head 53, a second head 55 and a connecting shaft 57. The grinding tool 51 is rotatable about a central rotational axis X2. The first head 53 comprises a first grinding contact surface 53A configured to machine the first chamfer 43. The second head 55 comprises a second grinding contact surface 55A configured to machine the second chamfer 45. The first grinding contact surface 53A comprises a diamond coating which is electro-plated onto the first head 53. The diamond coating comprises diamonds having a grain size in the range 300pm to 700pm. The first grinding contact surface 53A is part conical and is inclined at an angle of approximately 15° to the rotational axis X2. The second grinding contact surface 55A comprises a diamond coating which is electro-plated onto the second head 55. The diamond coating comprises diamonds having a grain size in the range 300pm to 700pm. The second grinding contact surface 55A is part conical and is inclined at an angle of approximately 30° to the rotational axis X2. The first and second grinding contact surfaces 53A, 55A are inclined in opposite directions to each other. In the present embodiment, the grinding tool 51 is configured to form the first and second chamfers 43, 45. In a variant, separate grinding tools may be used to form the first and second chamfers 43, 45. At least a portion of the first head 53 is inserted into the first cylinder bore 23-1 from a first end thereof. The second head 55 is configured also to be inserted into the first cylinder bore 23-1 from the first end thereof. In particular, the diameter of the second head 55 is less than that of the first cylinder bore 23-1. The second head 55 is inserted axially into the first cylinder bore 23-1 from the first end and the grinding tool 51 rotated about the rotational axis X2. The grinding tool 51 is displaced relative to the cylinder block 1 (for example in a radial direction) to bring at least one of the first and second heads 53, 55 into contact with the cylinder liner 25-1. The grinding tool 51 is then displaced along an orbital path to perform a grinding operation around the perimeter of the first cylinder bore 23-1, thereby forming at least one of the first and second chamfers 43, 45. The grinding tool 51 completes one or more orbits during each grinding operation. The grinding tool 51 could be configured to form the first and second chamfers 43, 45 at the same time. For example, the axial spacing of the first and second heads 53, 55 could correspond to the axial spacing between the first and second chamfers 43, 45. In the present embodiment, however, the grinding tool 51 is configured to form the first and second chamfers 43, 45 in separate machining operations. The axial spacing between the first and second heads 53, 55 is greater than the axial spacing between the first and second chamfers 53, 55. In particular, the axial spacing of the first and second heads 53, 55 at least substantially corresponds to the axial spacing between the first chamfer 43 and the undercut 39. During a first machining operation, the first head 53 is disposed axially within the first cylinder bore 23-1 to form the first chamfer 43; and the second head 55 is aligned axially with the undercut 39. In the position shown in Figure 3, the second head 55 is displaced downwardly out of a lower end of the first cylinder bore 23-1 for the first machining operation. The first head 53 of the grinding tool 51 is operative to form the first chamfer 43 while the second head 55 is disposed in the undercut 39. During a second machining operation, the second head 55 is disposed axially within the first cylinder bore 23-1 to form the second chamfer 45; and the first head 53 is displaced out of the first cylinder bore 23-1. In the position shown in Figure 5, the first head 53 is displaced upwardly out of an upper end of the first cylinder bore 23-1 for the second machining operation. As shown in Figure 6, the second head 55 of the grinding tool 51 is operative to form the second chamfer 45 while the first head 53 is disposed outside the first cylinder bore 23-1. The first head 53 comprises a plurality of first apertures 59 fortransporting debris, such as swarf, away from the contact surface during a machining operation. The first apertures 59 are in the form of channels in the present embodiment and are open in at least one axial direction. The first apertures 59 in the present embodiment extend in an axial direction substantially parallel to the rotational axis X2 of the grinding tool 51. The first head 53 may optionally comprise one or more first coolant supply ports 61 for supplying cooling to the contact surface. In the present embodiment, at least one coolant supply port 61 is disposed in each of the first apertures 59. The second head 55 comprises a plurality of second apertures 63 fortransporting debris, such as swarf, away from the contact surface during a machining operation. The second apertures 63 are in the form of channels in the present embodiment and are open in at least one axial direction. The second apertures 63 in the present embodiment extend in an axial direction substantially parallel to the rotational axis X2 of the grinding tool 51. The second head 55 may optionally comprise one or more second coolant supply ports 65 for supplying cooling to the contact surface. In the present embodiment, at least one second coolant supply port 65 is disposed in each of the second apertures 59. The application of the thermal spray coating typically results in the deposition of material to the cylinder block face 37. A machining operation may be performed to machine the cylinder block face 37. This may be performed before or after forming the first chamfer 43 in the first end region 33 of the first cylinder 11. Preferably, the cylinder block face 37 is machined after forming the first chamfer 43 to help avoid damaging the cylinder liner 25-1, for example by separating the thermal spray coating from the internal surface 27 of the first cylinder bore 23-1. At least one of the first and second chamfers 43, 45 is formed in the cylinder block 1 by a grinding operation. In the embodiments described herein, the first and second chamfers 43, 45 are formed by first and second grinding operations respectively. The grinding operations are effective in reducing the thickness of the cylinder liner 25-1 at the first and second end regions of the first cylinder bore 23-1. It has been determined that grinding is effective in forming the first and second chamfers 43, 45 without separating the thermal coating from the internal surface 27 of the casting block 21. This helps to maintain integrity of the cylinder block 1. The surface finish of the first and second chamfers 43, 45 is Identifiable as being performed by a grinding operation, rather than other subtractive machining operations (such as turning). At least in certain embodiments, the grinding tool 51 is displaced relative to the casting block 21 in a plane substantially perpendicular to the central axis X1 of the first cylinder bore 23-1. This in-plane movement may help to reduce the forces applied to the cylinder liner 25-1 during the machining operation. For example, the first head 43 and / or the second head 45 may contact the casting block 21 at an acute angle. At least in certain embodiments, this may help to preserve integrity of the cylinder liner 25-1, particular at the interface between the cylinder liner 25-1 and the casting block 21. The grinding tool 51 has been described herein as following an orbital path to form the first and second chamfers 43, 45. The grinding tool 51 may follow a spiral path of increasing diameter progressively to form the first chamfer 43 and / or the second chamfer 45. The grinding tool 51 may follow a circular orbit to finish the grinding operation. The present embodiment has been described with reference to a cylinder block 1 having first and second chamfers 43, 45 formed at respective first and second end regions of the first cylinder bore 23-1. In a variant, the cylinder block 1 may have only the first chamfer 43, or only the second chamfer 45. The method of forming the cylinder block 1 may be modified accordingly. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A cylinder block (1) of an internal combustion engine (3), the cylinder block (1) having a cylinder bore (23-n) for receiving a piston (15-n), wherein the cylinder block (1) is composed of an alloy having a thermal spray coating (SC) disposed on an internal surface of the cylinder bore (23-n);wherein a first chamfer (43) is formed in a first end region (33) of the cylinder bore (23-n), the first chamfer (43) forming a first taper in the thermal spray coating (SC) in a first direction away from the cylinder bore (23-n),2. A cylinder block (1) as claimed in claim 1, wherein the first chamfer (43) is formed by a grinding operation.

3. A cylinder block (1) as claimed in claim 1 or claim 2, wherein the first taper is a constant taper.

4. A cylinder block (1) as claimed in any one of claims 1,2 or 3, wherein the first taper is inclined at a first angle (a1) to a central longitudinal axis (X2) of the cylinder bore (23-n), the first angle being less than or equal to 45°.

5. A cylinder block (1) as claimed in any one of the preceding claims, wherein the first chamfer (43) extends through the thermal spray coating (SC).

6. A cylinder block (1) as claimed in any one of the preceding claims, wherein a second chamfer (45) is formed in a second end region (35) of the cylinder bore (23-n), the second chamfer (45) forming a second taper in the thermal spray coating (SC) in a second direction away from the cylinder bore (23-n).

7. A method of forming a first end region (33) of a cylinder bore (23-n), the cylinder bore (23-n) being disposed in a cylinder block (1) of an internal combustion engine (3) and being configured to receive a piston, wherein the cylinder block (1) is composed of an alloy and a thermal spray coating (SC) is disposed on an internal surface of the cylinder bore (23-n);wherein the method comprises forming a first chamfer (43) in the first end region (33) of the cylinder bore (23-n), the first chamfer (43) comprising a first taper in the thermal spray coating (SC) in a first direction away from the cylinder bore (23-n).

8. A method as claimed in claim 7, wherein the method comprises using a grinding tool (51) to form the first chamfer (43) in a first grinding operation.

9. A method as claimed in claim 8, wherein the grinding tool (51) comprises:a first grinding contact surface (53A) comprising a diamond coating operative to grind both the thermal spray coating (SC) and the alloy cylinder block (1).

10. A method as claimed in claim 8 or claim 9 comprising:introducing at least a portion of the grinding tool (51) into the cylinder bore (23-n); anddisplacing the grinding tool (51) in a direction substantially perpendicular to a rotational axis of the grinding tool (51) to bring the first grinding contact surface (53A) into contact with the thermal spray coating (SC) on the internal surface of the cylinder bore (23-n).

11. A method as claimed in any one of claims 7 to 10, wherein the method comprises:forming a second chamfer (45) in a second end region (35) of the cylinder bore (23-n), the second chamfer (45) comprising a second taper in the thermal spray coating (SC) in a second direction away from the cylinder bore (23-n).

12. An internal combustion engine comprising a cylinder block as claimed in any one of claims 1 to 6.

13. A vehicle comprising a cylinder block as claimed in any one of claims 1 to 6 or an internal combustion engine as claimed in claim 12.13

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