Technical field [001] The present invention relates to a camshaft assembly for an internal combus tion piston engine according the preamble of the claim 1. Invention relates also to a method of assembling a camshaft assembly into an engine block.

Background art [002] In the internal combustion piston engines, pistons are arranged to reciprocate in a cylinder and the reciprocating movement of the pistons is transferred into rota tional movement of the crankshaft. There is a camshaft arranged to operate gas ex change valves in each cylinder of the engine. A camshaft consist of a cylindrical rod running along the length of the cylinder bank with a number of cams protruding from it. The cams force the valves open by providing pressing force on the valve as the cams rotate.

[003] Internal combustion piston engines are today’s one of the most efficient means of converting gaseous or liquid fuel into energy. In emerging gas markets it is possible to build the engine operating initially on liquid fuel and later being converted to operate on gaseous fuel. This also works the other way around if so desired. When the gas supply is uncertain, or prices are volatile, it is possible to perform the mechanical conversion of the engine from gaseous fuel operation to liquid fuel operation. The document discloses a connector assembly which is disposed radially within a cylin drical bearing surface of a bearing carried by housing. The connector provides dual functionality of connecting camshafts together, while at the same time defining a bear ing surface which is rotatably carried within a bearing of the engine housing. By com bining the connector and bearing functions together, the overall length of internal com bustion engine is said to be reduced. Cam sets are sequentially arranged axially ad jacent to each other along the length of camshaft. Between each axially adjacent pair of cam sets, camshaft also includes a cylindrical bearing which is disposed within and rotatably carried by a corresponding cylindrical interior bearing surface of a bearing in the engine housing. Camshaft is thus intermittently rotatably supported along the length thereof by engine housing. This kind of segmented camshaft assembly has a problem of at least relating to complexity of the bearing surface due to the integrated connector, being this way prone to misalignment.

[004] An object of the invention is to provide a camshaft assembly, which is simple to assemble and reliable in use and considerably improved compared to the prior art solutions. Disclosure of the Invention

[005] Objects of the invention can be met substantially as is disclosed in the inde pendent claims and in the other claims describing more details of different embodi ments of the invention.

[006] A camshaft assembly for an internal combustion piston engine comprises a first end part and a second end part and between the first end part and the second end part an intermediate section. The assembly comprises cams of the camshaft as sembly, and bearing surfaces by means of which the camshaft assembly can be ro tatably supported to a block of the engine. The intermediate section comprises a num ber identically constructed segments which are arranged on a common longitudinal axis, wherein each one of the segments comprises a timing member and a segment member: the timing member comprising a first axial end and a second axial end, a first circular array of bolt holes at the first axial end of the timing member, a second circular array of bolt holes at the second axial end of the timing mem ber, and the segment member comprising a first axial end and a second axial end, an outer bearing surface at the first axial end of the segment member, the outer bearing surface extending in axial direction, a third circular array of bolt holes at the first axial end of the segment member, a fourth circular array of bolt holes at the second axial end of the segment member, and cam surfaces of the camshaft assembly.

[007] The camshaft assembly according to the invention is simple to assemble, but still reliable in use. Also, by means of the invention it is possible to accomplish a retrofit with a stronger camshaft to old engines which have already defined dimensions of bearing housings. In retrofit, it is desired use the old engine block for minimizing the parts needed to be changed. Typically, in a retrofit the valve slopes are changed to have more steep slopes. This in turn means that forced involved in lifting the valves and/or pumping are increased. By means of the present invention an engine can be renewed so as to be more efficient and to operate with lower emissions, with the orig inal bearing housing dimensions.

[008] According to an embodiment of the invention the segment member comprises a first segment member and a second segment member, wherein the first segment member comprising a first axial end and a second axial end, a circular outer bearing surface at the first axial end of the first segment member, the outer bearing surface extending in axial direction, a third circular array of bolt holes at the first axial end of the first segment member, a fifth circular array of bolt holes at the second axial end of the first segment member at least one cam surface between the first and second axial end of the first segment member and wherein the second segment member comprising a first axial end and a second axial end, a sixth circular array of bolt holes at the first axial end of the second segment member, the fourth circular array of bolt holes at the second axial end of the second segment member, at least one cam surface between the first and second axial ends, and wherein the segment members comprise collectively three cam surfaces ar ranged in axially successive manner. [009] According to an embodiment of the invention the first segment member com prises one cam surface and the second segment member comprises two cam sur faces.

[0010] According to an embodiment of the invention the cam surface in the first seg ment member is configured to operate a fuel pump when assembled to an engine, and the cam surfaces in the second segment member is configured to operate gas exchange valves when assembled to an engine.

[0011] According to an embodiment of the invention the first circular array of bolt holes comprising a plurality of axially directed first holes, having a first hole pattern, the second circular array of bolt holes comprising a plurality of axially directed second holes, having a second hole pattern, the third circular array of bolt holes comprising a plurality of axially directed third holes, having a third hole pattern, the fourth circular array of bolt holes comprising a plurality of axially directed fourth holes, having a fourth hole pattern, wherein the first hole pattern is compatible for bolt attachment with the fourth hole pattern, and the second hole pattern is compatible for bolt attachment with the third hole pattern.

[0012] According to an embodiment of the invention the first circular array of bolt holes comprising a plurality of axially directed first holes, having a first hole pattern, the second circular array of bolt holes comprising a plurality of axially directed second holes, having a second hole pattern, the third circular array of bolt holes comprising a plurality of axially directed third holes, having a third hole pattern, the fourth circular array of bolt holes comprising a plurality of axially directed fourth holes, having a fourth hole pattern, the fifth circular array of bolt holes comprising a plurality of axially di rected fifth holes, having a fifth hole pattern, the sixth circular array of bolt holes com prising a plurality of axially directed sixth holes, having a sixth hole pattern, wherein the first hole pattern is compatible for bolt attachment with the fourth hole pattern, and the second hole pattern is compatible for bolt attachment with the third hole pattern, and the fifth hole pattern is compatible for bolt attachment with the sixth hole pattern.

[0013] According to an aspect of the invention the hole patterns are configured to allow setting of rotational positions of the segment members such that their rotational positions complies with firing order of successive cylinders, when assembled for use in a four stroke internal combustion piston engine. [0014] According to an embodiment of the invention the first circular array of bolt holes of the timing member comprise a plurality of axially directed first holes, the cen ters of which forming a first diameter, and the second circular array of bolt holes of the timing member comprise a plurality of axially directed second holes, the centers of which forming a second diameter smaller than the first diameter, and that the timing member comprises a first axial end portion having a cylindrical outer surface and a second axial end portion having a cylindrical outer surface wherein the first axial end portion has greater diameter than the second axial end portion.

[0015] According to an embodiment of the invention the first holes are blind holes in the first axial portion and the second holes extend axially through the timing member, and the diameter of the first axial portion is greater than diameter of the bearing sur face of the segment member.

[0016] According to an embodiment of the invention and the first holes are provided with threaded holes and the second holes are provided with non-threaded holes, and the diameter of the first axial portion is greater than diameter of the bearing surface of the segment member.

[0017] Advantageously the second axial portion has a cylindrical outer surface and the second axial portion has diameter which is substantially equal to the diameter of the bearing surface of the segment member.

[0018] Advantageously the third circular array of bolt holes is arranged to the axial location of the outer bearing surface in the segment member.

[0019] Advantageously the fourth circular array of bolt holes is arranged to the axial location of a second cam surface in the second end of the segment member.

[0020] Method of assembling a camshaft assembly into an engine block according to an embodiment of the invention comprise the following steps: a) the first segment member is assembled through the service opening inside the engine block such that the outer bearing surface is inserted into the bearing in the through hole of the bulkhead b) the first segment member is moved axially to a position which is axially farther inside the bearing than the final operational position of assembly, c) the timing member is attached to the end of the previously installed first segment d) the second segment member is attached either to one of the first axial end of the timing member (108.3) and the second axial end of the first segment member (108.1) e) the first segment member is moved axially and the segment members are attached axially to each other.

[0021] According to an embodiment of the invention the steps are practised in the order a) b) c) d) e).

[0022] [0024] According to an embodiment of the invention the steps are practised in the order c) a) b) d) e).

[0023] Method of assembling a camshaft assembly into an engine block accord ing to an embodiment of the invention comprise the following steps: a) the segment member is assembled through the service opening inside the engine block such that the outer bearing surface is inserted into the bearing in the through hole of the bulkhead, b) the segment member is moved axially to a position which is axially farther inside the bearing than the final operational position of assembly, c) the timing member is attached to the end of the installed segment member, d) the adjacent segment members is attached to each other by means of the timing member such that the timing member is between the adjacent segment members .

[0024] By means of the term “cam surface” it is meant the guide surface circumscrib ing the camshaft, against which surface a follower runs to get its position guide when in use. This is often referred to as cam lobe as well. The follower is coupled to for example to operate a fuel pump or gas exchange valve of the engine.

[0025] The exemplary embodiments of the invention presented in this patent applica tion are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. Brief Description of Drawings

[0026] In the following, the invention will be described with reference to the accom panying exemplary, schematic drawings, in which

Figure 1 illustrates a camshaft assembly according to an embodiment of the invention, Figure 2 illustrates a segment member of camshaft assembly according to an embod iment of the invention,

Figure 3 illustrates a timing member of camshaft assembly according to an embodi ment of the invention,

Figure 4 illustrates a segment member of camshaft assembly according to another embodiment of the invention,

Figure 5 illustrates an attachment hole configuration in a segment member of cam shaft assembly according to another embodiment of the invention,

Figure 6 illustrates a principal of attachment of successive segment members accord ing to an embodiment of the invention, Figure 7 illustrates principle of assembling a camshaft assembly according to an em bodiment of the invention,

Figure 8 illustrates a timing member of camshaft assembly according to another em bodiment of the invention, and

Figure 9 illustrates principle of assembling a camshaft assembly according to another embodiment of the invention.

Detailed Description of Drawings

[0027] Figure 1 depicts schematically a camshaft assembly 10 according to an em bodiment of the invention. The camshaft assembly is configured to be operable in a four stroke internal combustion piston engine in which, for operating gas exchange valves and a fuel pump in connection with each cylinder of the engine. The engine is depicted by the block 1 of the engine. The engine comprises in the figure 1, denoted by the reference 12, a fuel pump assembly of each cylinder of the engine. The refer ence 14 denotes a gas exchange valve assembly, such an intake valve assembly, of each cylinder of the engine. The reference 16 denotes a gas exchange valve assem bly, such as an exhaust gas valve assembly, of each cylinder of the engine. Figure 1 shows a camshaft assembly 10 in the multi cylinder engine for a row of cylinders thereof. The engine is provided with a first actuating mechanism 12.1 in connection with each cylinder of the engine, which operates the fuel pump assembly 12. The engine is also provided with a second actuation mechanism 14.1 and a third actuation mechanism 16.1 in connection with each cylinder of the engine which operate the intake, and respectively, exhaust gas valve assembly.

[0028] In the figure 1 the camshaft assembly is shown assembled in an engine block 1 and supported to the block 1 rotatably by a number of bearings 20. The bearings 20 are arranged to successive and coaxial through-holes 2 arranged to the bulkheads 4 in the block 1. The second bulkhead 4 from the left in the figure 1 is a cut-out at different elevation than the others, indicating that the hole 2 is arranged to solid bulk head which cannot be split into two halves for installation of the camshaft assembly, but the assembly and disassembly is made possible via access through service open ings 6 at a side wall of the block 1 of the engine.

[0029] The camshaft assembly 10 comprises a first end part 102 and a second end part 104. Even if not shown here at least one of the end part is provided with power transmission means, such as a gear wheel, for rotating the camshaft assembly. Be tween the first end part 102 and the second end part the camshaft assembly 10 com prises an intermediate section 106. The intermediate second comprises necessary cams of the camshaft assembly for operating the cylinder specific fuel pumps and gas exchange valve mechanisms. The intermediate section is also provided with outer circular bearing surfaces 21 for each bearing 20, for supporting the camshaft assem bly 10 to the block 1 of the engine.

[0030] More specifically the intermediate section is constructed of number of advan tageously identical segments 108 which are arranged one after the other between the end parts 102,104 to a common longitudinal rotational axis A. The engine comprises one segment 108 per each of its cylinder. There is also one bearing 20 for each of the cylinder in a row and one end bearing. In the following, an embodiment of such seg ment 108 is described with a reference to the figure 2 in more detailed manner.

[0031] Each one of the segments 108 comprises, according to an embodiment shown in the figure 2, three separate parts. The left side view I shows the parts axially sepa rated from each other and the right side view II shows the parts attached to each other forming the segment 108. Referring to the view II of the figure 2 the segment 108 comprises a segment member 108.0 and a timing member 108.3. The segment member 108.0 is comprised of a first segment member 108.1, a second segment member 108.2 as is shown in the view I. The first segment member 108.1, the second segment member 108.2, and the adjustment member 108.3 are remova bly attached to each other at their axial ends to form one segment 108 of the interme diate section 106 as is shown in the view II. The adjustment member 108.3 is config ured such that two successive segment members 108.0 can be attached to it, one on the first axial end and the other on the second axial end, such that the segment mem bers 108.0 are at different angular position i.e. at different rotational positions in re spect to the rotational axis A. The positions are predetermined such that mutual posi tions of the segment members 108.0 in the camshaft assembly 10 correspond to and comply with the preset firing orders of respective successive cylinders of the engine. Each one of the segment members 108.1, 108.2 and the timing member 108.3 com prise advantageously a guide recess 111 at its first axial end and a guide extension 113 at its second axial end collectively called a guides. The guides are rotationally symmetric in respect to the rotational axis A. The guide extension 113 extends from the second axial end of each one of the members and the guide recess is an inden tation at the first ends of the members. The guides are configured so that the guide extension fits both radially and axially inside the guide recess 111. By means of the guides it is ensured that the members of the assembly are aligned properly during the installation. If the forms and/or dimensions of the guide extensions and recesses are different at different joints, a correct assembly order of the members can be ensured.

[0032] The first segment member 108.1 comprises a first axial end 110 and a second axial end 112, and a circular outer bearing surface 122 at the first axial end 110 of the first segment member 108.1. The outer bearing surface 122 extends in axial direction to be suitable for the engine’s respective bearing 20 and has a diameter which is compatible with the bearing 20 in the bulkhead so as to advantageously form a slide bearing. Next functional part of the first segment member 108.1 is a cam surface 124. The cam surface 124 is arranged at a distance axially from the bearing surface 122. The first segment member 108.1 comprises one cam surface 124 and which - when assembled to an engine - is preferably configured to operate a cylinder specific fuel pump, which may be for example a high pressure jerk pump. At its second axial end 112 the first segment member 108.1 is provided with radially outwards extending at tachment flange 123, provided with an array of bolt holes. Since the bearing surface 122 is an integral part of the first segment member 108.1 at its first axial end, there is no flange joint between the bearing surface 122 and the cam surface 124 in the first segment member 108.1 making the connection between the bearing and the resr of the segment member very strong.

[0033] The second segment member 108.2 comprises a first axial end 114 and a second axial end 116. The second segment member 108.2 further comprises two cam surfaces 126, 128. The cam surfaces 126, 128 are arranged at a distance axially from each other, at the opposite ends of the second segment member 108.2. The first cam surface 126 of the second segment member 108.2 is configured to operate intake valve mechanism (14.1 in the figure 1) while the second cam surface 128 of the sec ond segment member 108.2 is configured to operate exhaust valve mechanism (16.1 in the figure 1) - or vice versa. The cam surfaces are arranged at radial surface of cam lobes extending radially from generally circular outer surface of the second seg ment member 108.2 between the cam lobes. The cam lobes are provided with an array of bolt holes forming thus also attachment flanges. Advantageously, the first one of the lobes is provided with bolt holes without internal thread and second one of the flanges is provided with bolt holes with internal thread. The holes without the thread are through-holes and the holes with internal thread are advantageously blind holes.

[0034] Now referring to the figure 3, the timing member 108.3 comprises a first axial end 118 and a second axial end 120. The timing member 108.3 has generally two axial end portions which have different diameters. The axial portions have also generally cylindrical outer surface. The first axial portion at the first axial end 118 has a first diameter and the second axial portion at the second axial end 120 has a second diameter. The first axial end portion has greater diameter (a radial extension) than the second axial end portion, such that one cylindrical array of holes can be arranged to the radial extension of the first axial end. The timing member 108.3 comprises a first circular array of bolt holes 130 at the first axial end of the timing member 108.3, at the region of the first axial end portion. The first circular array of bolt holes with internal thread and the holes may be blind holes. The timing member 108.3 comprises also a second circular array of bolt holes 132. The first circular array of bolt holes 130 com prise a plurality of axially directed first holes, having a first hole pattern and the second circular array of bolt holes 132 comprising a plurality of axially directed second holes, having a second hole pattern. In the embodiment of the figure 3 the second array of bolt holes 132 comprises two circular rows of holes, the first row 132.1, and the sec ond row 132.2, the holes arranged in staggered pattern. By means of the feature of having two circular rows of holes it is possible to have more attachment bots fitted. However, this is only an optional embodiment and the second array of bolt holes may also be comprised of a single row of second circular array of bolt holes 132 as is shown in the figure 8. In other respects the timing member 108.3 corresponds to that shown in the figure 3. The holes in the second array are non-threaded through-holes having a radially extended, axial recess space at the first axial end 118 for sinking a head of a used attachment bolt below the end surface of the first axial end 118.

[0035] As it becomes clear from the figure 3 the first circular array of bolt holes 130 of the timing member 108.3 comprise a plurality of axially directed first holes in a circular pattern, the centers of individual circular holes form a first diameter. Respec tively the second circular array of bolt holes 132 of the timing member 108.3 comprise a plurality of axially directed second holes in a circular pattern, the centers of which forming a second diameter, which second diameter smaller than the first diameter. Even if the second array of bolt holes 132 comprises two rows of holes, the first row 132.1, and the second row 132.2, the first diameter can be understood to be related to either one of the rows of holes, since both are arranged radially inside the first diameter. The timing member comprises a first axial end portion having a cylindrical outer surface and a second axial end portion having a cylindrical outer surface wherein the first axial end portion has greater diameter than the second axial end portion and the first holes are blind holes in the first axial portion and the second holes extend axially through the timing member 108.3.

[0036] The diameter the first axial portion is greater than diameter of the bearing surface of the segment member 108.0 against which the second end of the timing member 108.3 is attached when assembling the camshaft assembly. The diameter of the second axial portion at the second end 120 of the timing member 108.3 is sub stantially equal to the diameter of the first end 110 of the segment member 108.0.

[0037] Figure 6 depicts the attachment of successive segment members 108.0 bridged by the timing member 108.3 in connection with the bulkhead 4 of the engine. As can be seen from the figure, the second row of bolt holes 132 extends axially through the timing member 108.3 and meshes with the third row of bolt holes 132’ in the timing member 108.3. The holes of the third row of bolt holes 132’ are blind holes provided with internal thread. Since the circular array of the second row of bolt holes 132 is radially inside the first circular array of bolt holes 130, and the second row of bolt holes 132 comprises through-holes, which means that there is not needed space for the heads of the bots around the shaft assembly at the vicinity of the bearing and the bulkhead. In the segment member 108.0 the individual holes extend axially under the outer bearing surface 122. In other words, in the camshaft assembly the third circular array of bolt holes 132’ is arranged to the axial location of the outer bearing surface 122 in the segment member 108. This way a conventional, flange attachment using radially outwardly extending flanges between the bearing section and the shaft part joining the bearing section can be avoided and the diameter of the shaft part i.e. the timing member 108.3 joining the bearing section can be substantially equal to the diameter of the bearing section.

[0038] Referring to the figure 4, the segment member 108.0 is according to an em bodiment of the invention a one-piece unit. This embodiment is applicable to such engine which dimensions allow the assembly of the one-piece unit segment member 108.0 into the engine, as is shown in the figure 9. It is possible to facilitate the assem bly of the segment member 108.0 and the timing member 108.3 by selecting the axial lengths of the segment member and the timing member 108.3 so that both of the parts can be positioned in the engine via the service openings 6 of the engine. Figure 4 shows the segment member 108.0 in the middle, and its end views on the right and left sides, respectively. Even if the timing between the fuel pump stroke (position of the apex of the cam surface 124) and valve positions is not adjustable, the one-piece segment member 108.0 provides various advantageous effects, such as making it possible to assemble the camshaft from a number of identical segment members 108.0 and timing members 108.3. The segment member 108.0 comprises a first axial end 110, which correspond to the first axial end 110 of the first segment member 108.1 in the figure 2, and a second axial end 116 which correspond to the a second axial end 116 of the second segment member 108.2 in the figure 2. The segment member 108.0 comprises the outer bearing surface 122 at the first axial end thereof, and cam surfaces 124,126,128 for the fuel pump force transmission and operating the gas exchange valves, correspondingly to the figure 2. Further, the segment mem ber 108.0 comprises a third circular array of bolt holes 132’ at the first axial end 110 of the segment member 108.0, and a fourth circular array of bolt holes 130’ at the second axial 116 end of the segment member 108.0. The third circular array of bolt holes 132’ comprising a plurality of axially directed third holes, having a third hole pattern, and the fourth circular array of bolt holes 130’ comprising a plurality of axially directed fourth holes, having a fourth hole pattern. The fourth circular array of bolt holes 130’ comprises a number of through-holes arranged axially at the location of a second cam surface 128 in the second end of the a segment member 108.0.

[0039] Now, the first hole pattern of the first circular array of bolt holes 130 in the timing member 108.3, is compatible for bolt attachment with the fourth hole pattern of the fourth circular array of bolt holes 130’, in the segment member 108.0, and the second hole pattern of the second array of bolt holes 132 in the timing member 108.3 is compatible for bolt attachment with the third hole pattern of the third circular array of bolt holes 132’ in the segment member 108.0. The bolt attachment is attachable at a number of different rotational positions corresponding the number of cylinders of a four stroke engine to which the cam shaft is useable. This way the segment members 108.0 may be coupled with each other bridged by the timing member 108.3 between them.

[0040] In other words, the pairs of the first circular array of bolt holes 130 - the fourth circular array of bolt holes 130’ and the second array of bolt holes 132 - the third circular array of bolt holes 132’ are configured so as to allow setting of rotational po sitions of the successive segment members 108.0 such that their rotational positions complies with firing order of respective successive cylinders, when assembled for use in a four stroke internal combustion piston engine. This way a cam shaft assembly for engines having different number of cylinders in a row can be assembled using identi cal same segment members 108.0 and the timing members 108.3.

[0041] Figure 5 shows in more detailed manner the attachment hole’s configuration in the segment member 108.0 according to an embodiment of the invention shown in the figure 2. The segment member 108.0 is comprised of a first segment member 108.1 and a second segment member 108.2. The first segment member 108.1 com prises a first axial end 110 and a second axial end 112. As already shown in connec tion with the figure 2 the first segment member 108.1 comprises the circular outer bearing surface 122 at the first axial end 110 for supporting the camshaft assembly to the block 1 of the engine. At its second axial end 112 the first segment member 108.1 is provided with radially outwards extending attachment flange 123, provided with an array of bolt holes. The first segment member 108.1 comprise a third circular array of bolt holes 132’ at the first axial end thereof, which array is similar to the embodiment of the figure 4. Further, there is a fifth circular array of bolt holes 134 at the second axial end of the first segment member 108.1. The fifth circular array of bolt holes 134 is arranged to the attachment flange 123. Respectively the second segment member 108.2 comprises a first axial end 114 and a second axial end 116. There is a fourth circular array of bolt holes 116 at the second axial end thereof, which array is similar to the embodiment of the figure 4. The second segment member 108.2 further com prises a sixth circular array of bolt holes 136 at the first axial end of the second seg ment member. In order to attach the first segment member 108.1 to the second seg ment member 108.2 the fifth hole pattern of the fifth circular array of bolt holes 134 is compatible for bolt attachment with the sixth hole pattern of the sixth circular array of bolt holes 136 at the first end of the second segment member 108.2. As it becomes clear from the figure 5 the first segment member comprise together and collectively three cam surfaces 124,126,128. The sixth circular array of bolt holes 136 comprises a number of blind-holes arranged to extend from the first end 114 of the second seg ment member 108.2 towards the second end 116 thereof at the location of the first cam surface 126 in the first end of the second segment member 108.2.

[0042] Forms of the eccentric lobes of the cam surfaces are shown only for illustrative purposes being not necessarily operable as such in practise.

[0043] Assembling of the camshaft assembly 10 to a block 1 and between the bulk heads 4 of an internal combustion piston engine is explained in the following with a reference to the figure 7. The assembly should also be understood such that is may be practised in retrofitting a new camshaft to an old engine from which the old cam shaft has been removed. The first view 7.1 shows a situation where the camshaft assemblies concerning the other cylinders than the first one in the left on the view already are in the engine. This represent the initial stage of installation of each seg ment 108. In the next step the first segment member 108.1 is assembled through the service opening 6 inside the engine such that the outer bearing surface 21 is inserted into the bearing 20 in the through hole 2 of the bulkhead 4. The first segment member 108.1 is aligned such that its rotational axis A is coaxial with a center longitudinal axis of the bearing 20 after which the first segment member 108.1 moved towards the bearing and further, the bearing surface 21 is moved into the bearing 20. The first segment member 108.1 is moved axially to a position which is axially deeper than the final operational position of assembly, in other words to an installation position. The installation position is deeper of a length L in the bearing 20 compared to the final operational position of assembly, this is depicted in the view 7.2. In practise the cam surface 124 in the first segment member 108.1 is limiting the range of axial movement into the bearing 20. The length L is at least equal to, or more than, the common axial length of the timing member, the guide recess 111 and the guide extension, if the guides are arranged to the members. Next, the timing member 108.3 is attached to the end of the previously installed first segment 108 associating with the adjacent cylinder. The timing member 108.3 needs to be attached to the first segment 108 before the second segment 108.2 is attached to the timing member 108.3 due to the radially nested arrays of circular bolt rows, as is described in the connection with the figure 3. This is shown in the view 7.3.

[0044] Next the second segment member 108.2 is attached to the first axial end of the timing member 108.3 which is shown in the view 7.4. Alternatively the second segment member is attached to the second axial end of the first segment member 108.1.

[0045] Finally the first segment member 108.1 is moved axially and the segment members 108.1, 108.2, 108.3 are attached axially to each other. As is depicted tin the view 7.5 the first segment member 108.1 is moved axially against the second segment member 108.2. The order of the step shown in the views 7.2 and 7.3 can be opposite to that described above i.e. the timing member 108.3 can be installed before the first segment member 108.1 is moved to the installation position.

[0046] Assembling of the camshaft assembly 10 to a block 1 and between the bulk heads 4 of an internal combustion piston engine according to another embodiment of the invention is explained in the following with a reference to the figure 9. The assem bly should also be understood such that is may be practised in retrofitting a new cam shaft to an old engine from which the old camshaft has been removed. The first view 7.1 shows a situation where the camshaft assemblies concerning the other cylinders than the first one in the left on the view already are in the engine. This represent the initial stage of installation of each segment 108. In the next step the segment member 108.0 is assembled through the service opening 6 inside the engine such that the outer bearing surface 21 is inserted into the bearing 20 in the through hole 2 of the bulkhead 4. The segment member 108.0 is aligned such that its rotational axis A is coaxial with a center longitudinal axis of the bearing 20 after which the segment mem ber 108.0 is moved towards the bearing and further, the bearing surface 21 is moved into the bearing 20. The first member 108.0 is moved axially to a position which is axially deeper than the final operational position of assembly, in other words to an installation position. The installation position is deeper of a length L in the bearing 20 compared to the final operational position of assembly, this is depicted in the view 9.2. Next, the timing member 108.3 is attached to the end of the previously installed seg- ment 108 associating with the adjacent cylinder as is shown in the view 9.3. Alterna tively the timing member 108.3 can be attached to the end of the later installed seg ment member 108.0

[0047] Finally, as is shown in the view 9.4 the segment member 108.0 is moved axi ally and the segment members 108.0 is attached to each other such that the timing member 108.3 is between two successive segment members 108.0..

[0048] While the invention has been described herein by way of examples in connec tion with what are, at present, considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the ap pended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible. [0049] Part list

1 an engine block 12.1 a first actuating mechanism of

2 through-holes the fuel pump assembly 4 bulkhead 14 a gas exchange valve assembly

6 service openings 35 14.1 a second actuation mechanism 10 a camshaft assembly 16 a gas exchange valve assembly 12 a fuel pump assembly 16.1 a third actuation mechanism 20 a bearing 116 a second axial end of the second

21 an outer circular bearing surfaces 25 segment member in intermediate section 118 a first axial end of the timing

102 a first end part of camshaft as- member sembly 120 a second axial end of the timing

104 a second end part of camshaft member assembly 30 122 a circular outer bearing surface

106 an intermediate section of cam 123 an attachment flange shaft assembly 124 a cam surface 108 segments of the intermediate 126 a cam surface section 128 a cam surface

108.0 a segment member 35 130 a first array of bolt holes

108.1 a first segment member 130’ a fourth array of bolt holes

108.2 a second segment member 132 a second array of bolt holes 108.3 a timing member 132.1 a first row of bolt holes

110 a first axial end of the first seg 132.2 a second row of bolt holes ment member 40 132’ a third array of bolt holes 111 a guide recess 132.1’ a third row of bolt holes

112 a second axial end of the first 132.2’ a fourth row of bolt holes segment member 134 a fifth array of bolt holes

113 a guide extension 136 a sixth array of bolt holes

114 a first axial end of the second segment member