Valve Actuating System For Reciprocating Machine

Abstract

A number of cylinder head arrangements that provide low cost and easy assembly of their various components with minimum labor and reduced necessity for line boring to reduce both manufacturing and assembly operation without adversely affecting performance.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates to reciprocating machines such as internal combustion engines or compressors of the type having a cylinder block having one or more cylinder bores that reciprocally support a piston or pistons that are connected a crankshaft at one end. The opposite end of these cylinder bores is closed by a cylinder head affixed to the cylinder block in a suitable manner. The flow into and out of the cylinder bores is controlled by valves reciprocally mounted in the cylinder head and operated by one or more camshafts journalled therein. Frequently the valves are operated from cams on the camshaft through pivotally supported rocker arms.

[0002] Although this arrangement is generally effective, a substantial number of machining and assembly steps are required to complete the assembly. This adds to the cost and can, if not closely controlled, present alignment problems that can introduce inaccuracies and less than desirable operation.

[0003] As an example of a prior art construction of this type, Japanese Published Application, Publication Number P2000-170506A shows a construction wherein an intake side camshaft and an exhaust side camshaft are journalled by underlying lower cam holders and overlying upper cam holders. The lower cam holders condition are fastened to the cylinder head via a first series of fasteners. In addition, the upper cam holder and lower cam holder are fastened to each other at positions spaced inward from the first fasteners. In addition the second fastening members each have a smaller diameter than the first fastening member.

[0004] It is also stated therein that that size reduction of the cylinder head is possible and the first fastening members also serve to resist undesired cocking of the rocker shafts. However much fitting and precise location is required for machining and assembly.

[0005] As a further disadvantage to this type of construction, to secure the positional accuracy of the rocker shaft support section formed on the lower cam carrier, line boring is necessary after the lower cam carriers are mounted independently on each cylinder head. Therefore, the scale of machining facilities for such line boring become larger.

[0006] In addition, since the rigidity of hole machining tools needs to be secured to secure the machining accuracy, size reduction of the tool diameter is difficult. Therefore, weight saving and size reduction of the rocker shaft are difficult and in turn, weight saving and size reduction of the rocker arm are also difficult.

[0007] Another prior art structure is shown in Japanese Patent Publication B 2537205. As shown therein each rocker shaft is configured to be supported pivotally on a respective one of a plurality of cam carriers. Therefore, when the cam carriers are assembled to the cylinder head, they need to be assembled in succession while rocker arms are fitted on the rocker shafts, causing complicated assembly work.

[0008] In addition, each rocker shaft should not to overlap the opening that receives the respective spark plug insert. Therefore the support section for each of the rocker shafts needs to be separately machined for each cam carrier, making positional accuracy is difficult to obtain.

[0009] Therefore it is a principal object of this invention to provide a simplified, low cost and easily manufactured and assembled arrangement for operating the valves of a multi cylinder and valve reciprocating machine.

SUMMARY OF THE INVENTION

[0010] This invention is adapted to be embodied in a low cost, easily manufactured and assembled valve actuating mechanism for a reciprocating machine having a cylinder head adapted to be affixed in closing relation to at least one cylinder bore formed in a cylinder block. A cam shaft carrier is affixed to the cylinder head and defines a cam shaft bore for journaling a bearing surface of a cam shaft. A rocker shaft journal is formed by the cam shaft carrier in parallel relation to the cam shaft bore and extends on at least one side of the cam shaft bore. A rocker arm is journalled by the rocker shaft journal and has a follower surface engaged by a cam lobe of the cam shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a top plan view of the cylinder head of a reciprocating machine constructed in accordance with a first embodiment of the invention, with the cam cover removed to more clearly show the construction.

[0012] FIG. 2 is a further enlarged view of this embodiment, with the cam shafts removed.

[0013] FIG. 3 is a side elevational view looking in the direction of the arrow 3 in FIG. 2 showing the valves operated in phantom.

[0014] FIG. 4 is a cross sectional view taken along the line 4-4 in FIG. 3.

[0015] FIG. 5 is a cross sectional view taken along the line 5-5 in FIG. 3.

[0016] FIG. 6a is an enlarged view taken generally along the line 6-6 in FIG. 2 and shows the condition when the associated valve is closed.

[0017] FIG. 6b is an enlarged view taken generally along the line 6-6 in FIG. 2 and shows the condition when the associated valve is opened.

[0018] FIG. 7 is a view in part similar to FIG. 2 and shows another embodiment of the invention.

[0019] FIG. 8 is a side elevational view looking in the direction of the arrow 7 in FIG. 6 showing the valves operated in phantom.

[0020] FIG. 9 is a top plan view, in part similar to FIG. 1, but with the cylinder head reversed, and shows still another embodiment of the invention.

[0021] FIG. 10 is a further enlarged view of the embodiment of FIG. 9, showing one of the center cam shaft carriers with the cam shafts removed.

[0022] FIG. 11 is a side elevational view looking in the direction of the arrow 11 in FIG. 10 showing the valves operated and the operating cam lobes in phantom.

[0023] FIG. 12 is a cross sectional view taken along the line 12-12 in FIG. 11.

[0024] FIG. 13 is a top plan view, in part similar to FIGS. 2, 7, and 10 showing only the two cam carriers of this embodiment provided at the opposite ends of the cylinder head

[0025] FIG. 14 is a cross sectional view of the embodiment of FIG. 13 taken along a plane passing through the axes of the rocker arm journals.

DETAILED DESCRIPTION

[0026] Referring now in detail to the drawings and initially to the embodiment of FIGS. 1-6, a multi-cylinder reciprocating machine is shown partially and is identified generally by the reference numeral 21. As will be readily apparent to those skilled in the art, the invention may be applied to either reciprocating internal combustion engines or compressors. However to simplify the disclosure only engine applications are illustrated.

[0027] In the illustrated embodiment of these figures (FIGS. 1-6), a cylinder head, indicated generally at 22 is suitably affixed to a cylinder block (not shown). Basically any number of cylinders and any engine configuration may be employed such as in line, v type or opposed.

[0028] In accordance with the invention, a plurality of cam carriers 23 are provided on the cylinder head 22 in a manner to be described shortly. The cam carriers 23 support for rotation an intake cam shaft 24 and an exhaust cam shaft 25 disposed parallel to each other. To this end, the cam carriers 23 are formed by a single lower piece 23a having lower bearing recesses 23i and 23e each associated with respective, axially spaced journal surfaces 24b and 25b of the respective intake and exhaust cam shafts 24 and 25

[0029] To further complete the journaling of the cam shafts 24 and 25, bearing caps 26i and 26e are affixed, in a manner to be described shortly, to the single lower piece 23a and the cylinder head 22. These bearing caps have bearing surfaces 26ib and 26eb that are complementary to the lower bearing recesses 23i and 23e. These bearing surfaces 26ib and 23i and 26eb and 23e embrace and journal the axially spaced cam shaft bearing sections 24b and 25b of the cam shafts 24 and 25, respectively.

[0030] The driven ends of the cam shafts 24 and 25 are also journalled directly in the end of the cylinder head 22 by end bearing caps also indicated by the reference numerals 26ie and 26ee.

[0031] Threaded fasteners 27 pass through bored holes 28 in the bearing caps 26i, and 26e and aligned holes 29 formed in the single lower pieces 23a to fix the elements together. At the driven end of the camshafts 24 and 25 the end bearing caps 26ie and 26ee are bored to cooperate with tapped holes formed in the cylinder head at the driven end. Finally the lower ends 27e of all of these threaded fasteners 27 are threaded into tapped holes formed in the cylinder head 22 to complete the assembly.

[0032] In addition a further pair of bored holes 28 are formed in axial alignment with the transverse center of the cylinder head 22 in the area of the single lower pieces 23a between the bearings 23i and 23e above tapped holes in the cylinder head 22 to receive further threaded fasteners 30 for additional security in retaining the lower pieces 23a when the bearing caps 26i and 26e are removed,

[0033] Continuing to refer primarily to FIG. 1, the intake cam shaft 24 is formed with a plurality of intake cams 24c, and the exhaust cam shaft 25 is formed with a plurality of exhaust cams 25c. These pluralities of cams 24c and 25c are each adapted to operate the intake and exhaust valves, to be described shortly, through respective intake and exhaust rocker arms 31 and 32.

[0034] To this end, the single piece 23a of each of the cam carriers 23 is formed with an intake side rocker shaft journal opening 23irj and an exhaust side rocker shaft opening 23erj in a rocker shaft support section 23ras located between the intake cam shaft bearing 23i and the exhaust cam shaft bearing 23e, as shown in FIGS. 2 and 3.

[0035] Intake and exhaust rocker shafts 33, 34, respectively, are supported by the rocker shaft support portions 23ras, as shown in FIGS. 1-4. The rocker shaft support section 23ras is provided on both sides of the cam shaft bearings 23i and 23e and extends in the same direction as the cam shafts 24, 25 (see FIG. 1).

[0036] The rocker shaft journal openings 23irj, 23erj are formed in the cam carrier 23 as through-holes passing through the rocker shaft support section 23ras. The rocker shafts 33, 34 are inserted in these rocker shaft through-holes 23irj, 23erj.

[0037] In addition to the structure as thus far described, the single lower piece 23a of each of the cam carriers 23 is formed with a hole 35 for a spark plug insert section between the intake rocker arm support 23irj and the exhaust rocker arm support 23erj. This hole extends in a direction perpendicular to the axial direction of these shaft receiving sections 23irj, 23erj, as shown in FIGS. 1, 2 and 4.

[0038] A cylindrical collar 36 is fitted In the hole 35 for each ignition plug insert section formed in the cam carrier 23, as shown in FIG. 1. Suitably mounted ignition plugs 37 serve the combustion chambers formed in part by the cylinder head 22 through the collars 36.

[0039] In addition to this purpose, the collars 36 also have the function of preventing the rocker shafts 33, 34 from slipping off the cam carrier 23. This is accomplished by forming the rocker shafts 33 and 34 with notches 33a and 34a, respectively to engage parts of the collar 36 for the prevention of their slipping-off.

[0040] It is arranged so that the linear thermal expansion coefficient of the collar 36 is different (either larger or smaller) than that of the cam carrier 23. This will insure that the collar 36 can be attached to and detached from the cam carrier 23 in a cold or a hot environment and subsequently the collar 36 will be prevented from slipping off the cam carrier 23 at room temperature. Such an arrangement improves handling properties of the cam carrier 23, as well as its assembling properties, and a slipping-off prevention condition can be realized of a minimum amount of play as compared with mechanical fasteners such as bolts.

[0041] As best seen in FIGS. 2 and 4, the cam carrier lower pieces 23a are formed with slots 23 as and intake side rocker arms 31 and exhaust side rocker arms, 32 are inserted in these slots 23 as. The rocker arms 31, 32 are formed with shaft insert holes 31a, 32a, respectively for journaling rocker arms 31 and 32 in the lower pieces 23a on their shafts 33 and 34.

[0042] With the intake side rocker arms 31 fitted in the slots 23 as of the cam carrier 23, the intake side rocker shaft 33 is inserted in the intake side rocker shaft through-holes 23irj and shaft insert hole 31a. Likewise, with the exhaust side rocker arm 32 fitted in the slot 23 as of the cam carrier 23, the exhaust side rocker shaft 34 is inserted in the exhaust side rocker shaft through-hole 23erj and shaft insert hole 32a. The rocker shafts 33, 34 are supported independently for each cam carrier 23, and pass through the rocker shaft support section 23ras of the cam carrier 23 and extend on both sides of the cam shaft bearing section 24b so as to be disposed parallel to the cam shafts 24, 25. Thus the rocker arms 31, 32 are supported for rotation by the rocker shafts 33, 34 on both sides of the cam shaft bearing section 26ib of the cam carrier 23.

[0043] When the intake side cam shaft 24 and exhaust side cam shaft 25 are rotated, each of the intake side cams 24c and exhaust side cams 25c depresses each of the intake side rocker arms 31 and exhaust side rocker arms 32 for opening or the action of the springs, to be described, releases the depression and permits the rocker arms and associated valves to move to the closed positions.

[0044] The cam carriers 23 are mounted approximately directly above each respective cylinder and configured such that all of the plurality of rocker arms 31, 32 supported on both sides of the cam shaft bearing section 26ib of the cam carrier 23, correspond to that respective cylinder. Thus and as best seen in FIG. 3, each of the valves, indicated generally by the reference numeral 38, serving a respective one cylinder are adapted to be opened/closed by the movement of the four rocker arms 31, 32 supported on the two rocker shafts 33, 34 of one cam carrier 23.

[0045] Referring now primarily to FIGS. 2-5, and 6a and 6b, it will be seen that the upper bearing halves 26ib and 26eb have the aforementioned aligned holes 29 through which the threaded fasteners 27 pass along with the aligned bores 28 of the single lower piece 23a for the fastening of these assemblies to the cylinder head 22 in the desired relation to the associated cylinder.

[0046] As another feature of the invention, the cam carriers 23 also cooperate to lubricate the valves and operating mechanism. To this end, the single lower piece 23a of each cam carrier 23 is formed with an oil passage, indicated generally at 39, shown in FIGS. 2, 3 and 6a and 6b. This oil passage receives 39 pressurized oil from the engine lubricating system in a suitable manner and communicates with oil passages 41, 42, respectively, extending toward the intake rocker shaft 33 and exhaust rocker shaft 34. These passages 41 and 42 communicate respectively with coaxial oil passages 43, 44, formed in the rocker arm shafts 33 and 34 respectively. To this end, the rocker shafts 33, 34 are each formed hollow inside and closed at both ends to form the oil passages 43 and 44.

[0047] The valve gear lubricating system also includes oil delivery notches 31d and 32d formed in the intake rocker arms 31 and exhaust rocker arms 32, respectively. These oil delivery notches 31d and 32d are formed at the outer ends of delivery passages 43 and 44 that communicate with the rocker arm passages 41 and 42, respectively and face toward the intake cams 24c and exhaust cams 25c, shown partially in FIGS. 6a and 6b. As best seen in FIG. 4, the rocker shafts 33, 34 are retained axially by notches 33a, 34a formed therein that are engaged by the collar 36.

[0048] The valves 38 associated with the structure already described, their operation and construction will now be described in more detail by reference to FIG. 3. Each valve 38 is of the poppet type and has a valve stem 45 that is supported for reciprocation in the cylinder head 22 by a respective valve guide 42 pressed or otherwise secured to the cylinder head 22. A valve head 46 at the lower end of the respective stem cooperates with a valve seat (not shown) fixed at the combustion chamber end of the cylinder head 22 to control the flow through a respective intake or exhaust port, not shown in this figure, but as well known to those skilled in this art.

[0049] The valves 38 are normally retained in closed positions, as also known in the art, by return springs 47 of a desired type, with coil springs shown by way of example. These springs 47 are loaded between retainers 48 engaged with the cylinder head 22 and keeper retainers 49 fixed to the upper ends of the respective valve stem 45 to normally urge the valves 38 to their closed positions as shown in FIGS. 3 and 6a.

[0050] As the respective cam shafts 24 and 25 rotate, their cam lobes 24c and 25c will act to drive the respective valves 38 to their opened positions as shown in FIG. 6b, with compression of the springs 47. Upon continued rotation of the respective cam shaft 24 and 25 their lobes 24c and 25c will move away from the stems 45 and the springs 47 will close the valves 38, as is well known in the art.

[0051] As has also been noted, the oil delivery system for lubricating the valve train including the cam shafts 24 and 25 and specifically their respective cam lobes 24c and 25c, the contacted surfaces of the rocker arms 31 and 32 and the stems of the operated valves insures adequate lubrication. However a system is also incorporated for controlling the amount of lubricant supplied to these areas so as to prevent excess oil flow. This system is described in connection with the exhaust valves but it should be understood that the intake valves are lubricated by the same type of flow controlling construction

[0052] The oil or other lubricant is delivered continuously to the hollow interior of the respective rocker arm shaft, this being the passage 44 in the case of the exhaust valves 45 from the carrier base 23a through a delivery opening 44i that is continuously open since the rocker arm shaft 34 does not rotate. However the rocker arm 32 does rotate and its delivery passage 42 only overlaps a discharge opening 44d in the associated rocker arm 32 only at the time the associated rocker arm is moved toward the valve opening positions, as shown by comparing FIG. 6b with FIG. 6a.

[0053] To summarize the operation of this embodiment, as the engine 21 operates and the cam shafts 24, 25 and their plurality of cams 24c, 25c rotate, and the cams 24c, 25c depress will sequentially pivot the rocker arms 31, 32, and the valve stems 33 are lowered along with their valve faces 32 air is taken in on the intake side and combustion gas is exhausted on the exhaust side as is well known in the art.

[0054] In a like manner, when the cams 24c, 25c rotate beyond the condition of depressing the rocker arms 31, 32, the valve stems 33 are raised by the action of the springs 47 and the valve faces 32 are also raised to close their respective seats (not shown) so that no air will be taken in on the intake side and no exhaust gas will be exhausted on the exhaust side. The lubrication of the operating mechanism is effected only when the valves are being operated so as to avoid excess lubrication.

[0055] Thus, as should be readily apparent to those skilled in the art, the embodiment of FIGS. 1-6 incorporates cam shafts 24, 25 having a plurality of cams 24c, 25c for depressing rocker arms 31, 32 journalled by a plurality of cam carriers 23 each formed integrally with cam shaft bearing sections 26ib and 26eb for supporting the cam shafts and rocker shaft support sections 23irj and 23erj for supporting rocker shafts 33 and 34. The rocker shafts 33, 34 each supported independently by a cam carrier 23, positioned in the rocker shaft support section 23ras of the cam carrier 23 and extending on both sides of the cam shaft bearing section 26ib. Thus the axes of the cam shafts 24, 25, support of the rocker arms 31, 32 on the rocker shafts 33, 34 on both sides of the cam bearing section 26ib of the cam carrier 23 are also parallel.

[0056] Therefore, since a plurality of cam carriers 23 are provided and the rocker shaft 33, 34 are adapted to pass independently through respective of the rocker shaft support sections 23ras of the cam carriers 23, not all the plurality of rocker shafts 33, 34 need be centered to facilitating assembly. Further, since the rocker shaft 33, 34 are divided for each cam carrier 23 and small in length, weight saving and size reduction can be effected. Further, smaller scale, machining facilities for the cam carriers 23 can be employed. In addition, the positional accuracy of the holes for supporting rocker shafts 33, 34 to the cam shaft bearing sections 26ib 26eb can be obtained easily, resulting in improvement in reliability. Moreover, the work in mounting the rocker shafts 33, 34 to the arm carrier 33 is decreased.

[0057] As added advantages, the rocker shaft support section 23ras extend on both sides of the cam shaft bearing section 26ib in the same direction as the cam shafts 24, 25 and is formed with slots 23 as for supporting the rocker arms 31, 32. The rocker shaft support section 23ras is formed with through-holes 23irj, 23erj passing therethrough across the slots 23 as, and the rocker shafts 33, 34 are inserted in the through-holes 23irj, 23erj. Therefore, since the rocker arms 31, 32 are held by the slots 23 as on both sides in the vicinity of the shaft insert holes 31a, 32a, the rigidity of the mounting of the rocker arms 31, 32 along with accurate movement of the rocker arms 31, 32, effecting higher rotation speed and improvement in reliability.

[0058] As a further advantage, the cam carriers 23, the rocker shafts 33, 34 and the rocker arms 31, 32 have passages 39, 41, 42, 43, 44 for oil supplied from the cylinder head 22 and the rocker shaft 33, 34 are hollow inside and closed at both ends with the notches 33a, 34a being covered by the collar 36. Therefore, leakage of oil passing through the rocker shafts 33, 34 from the notches 33a, 34a can be suppressed. This structure allows the hollow portions inside the rocker shaft 33, 34 to be increased in size, effecting weight saving of the rocker shafts 33, 34.

[0059] Although in the multi-cylinder internal combustion engine 21 according to the embodiment of FIGS. 1-6b, the rocker shafts 33, 34 also pass through the rocker shaft support section 23ras, this invention is not limited to that specific way the rocker shafts 33, 34 are supported. Also, although in this first embodiment, the rocker shafts 33, 34 extending on both axial sides of the cam shaft bearing section 26ib to be disposed parallel to the cam shafts 24, 25, this invention is not limited to the foregoing embodiment.

Embodiment of FIGS. 7 and 8

[0060] To this end, FIGS. 7 and 8 show another embodiment of the invention. In describing this embodiment as well as those following, the same parts as in previous embodiments of the invention are designated by same reference numerals and description will not be repeated, except as necessary for those skilled in the art to understand and practice this and other additional embodiments to be described.

[0061] This embodiment employs cam carriers identified generally by the reference numeral 123 (only one of which is shown). In this embodiment rocker shaft through-holes 123e, 123i are formed in respective rocker shaft support sections 123erj and 123irj positioned transversely outside a cam shaft bearing section, indicated generally at 124. The central part of this cam shaft bearing section 124 includes a portion defining a cylindrical opening 125 for receiving a respective collar (not shown) like the collars 36 of the previously described embodiment to hold a respective spark plug. These components are formed so that the linear thermal expansion coefficient of the collar 36 is different (either larger or smaller) than that of the cam carrier 123, as described in the previous embodiment. This will insure that the collar 36 can be attached to and detached from the cam carrier 123 in a cold or a hot environment and subsequently the collar 36 will be prevented from slipping off the cam carrier 123 at room temperature.

[0062] In this embodiment, unlike that of FIGS. 1-6 the spark plug collar receiving opening 125 is separated from the rocker arm support sections 123irj and 123erj by the remainder of the cam shaft bearing section 124. Other effects and functions are substantially the same as in the first described embodiment of this FIGS. 1-6, except that while the rocker shafts 33, 34 on which the rocker arms 31, 32 rotate, are disposed inwardly in the first embodiment, they are dispose outwardly in this embodiment.

Embodiment of FIGS. 9-14

[0063] Another embodiment of the invention is illustrated in FIGS. 9-14. Again where the elements of this embodiment are the same or substantially the same as components already described, those components have been identified by the same reference numerals as previously employed. Also and for the sake of brevity these components will be described only insofar as is necessary for those skilled in the art to practice this embodiment.

[0064] The engine associated with this embodiment and more particularly a cylinder head assembly thereof is indicated generally by the reference numeral 201. The cylinder head 201 of the multi-cylinder internal combustion engine in this embodiment is different from the multi-cylinder internal combustion engine 21 of first described embodiment of FIGS. 1-6b in the following aspects and is also shown in a reversed position therefrom.

[0065] Primarily, rather than operating all of the intake and exhaust valves associated with the same cylinder, the cam carriers, except for those at the ends of the of the cylinder head, as to be described shortly, operate one intake valve and one exhaust valve of pairs of the adjacent cylinders spanned by these paired, middle or central cam carriers, each of which is indicated generally by the reference numeral 223m.

[0066] Like the previous embodiments and as best seen in FIGS. 10-12, these middle cam carriers 223m are comprised of a single lower piece 223ma to which a pair of respective upper bearing halves 223mib and 223meb is affixed by threaded fasteners 227. These middle cam carriers 223m are each disposed between adjacent centermost cylinders, as should be readily apparent from FIG. 9. The construction for the support at the ends of the cylinder head assembly 201 will, as has been noted, described later.

[0067] Continuing to refer primarily to FIGS. 10-12, pairs of adjacent middle intake rocker arms 231c are supported on an intake pivot shaft 224 received in a suitable bore formed in single lower pieces 223ma of the middle cam carriers 223m. The inner ends of these middle intake rocker arms 231c are retained in slots 223mas formed at one side of the single lower piece 223ma.

[0068] In a like manner adjacent middle exhaust rocker arms 232c are supported on an exhaust pivot shaft 234 recieved in a suitable bore formed in the single lower pieces 223ma of the middle cam carriers 223m. The inner ends of these middle exhaust rocker arms 232c are also retained in slots 223mas formed in the single lower pieces 223ma of the middle cam carriers 223m.

[0069] The middle intake rocker arm shafts 224 and the middle exhaust rocker arm shafts 234 are retained in axial position in the slots 223mas and the single lower pieces 223ma of the middle cam carriers 223m in the manner now to be described. As with all of the embodiments described, threaded fasteners pass through bored holes in the respective components of the cam carriers of the embodiments. These bored holes in this embodiment are identified by the reference numerals 228. As with the previously described embodiments, the body of the cylinder head (201 in this embodiment) has tapped holes to threadingly engage and retrain the threaded lower ends of the fasteners 227. In addition and as best shown in FIG. 12, these fasteners 227 pass through a portion of the bores 228 which intersect the pivot shafts 224 and 234 and around which sleeves 229 are positioned to axially restrain them axially. These sleeves 229 are also received in notches 230 formed in the pins 224 and 234 to axially restrain them within their respective bores.

[0070] From the description of this embodiment as already made, it should be obvious to those skilled in the art, that provision must be made for operating one intake valve and one exhaust valve for the cylinders at opposite ends of the cylinder head 201. This structure may be best understood by reference to FIGS. 13 and 14. As already noted, FIG. 13 is a top plan view showing only this portion of the structure of this embodiment and FIG. 14 is a cross sectional view of the structure shown in FIG. 13 taken through the pivotal axes of the rocker arms. The end intake rocker arms are identified by the reference numerals 231e and the end exhaust rocker arms are identified by the reference numeral 232e.

[0071] Referring now first to FIG. 13 and remembering its relation to FIG. 9, at the respective left and right ends of the cylinder head 201, end cam carriers 223el and 223er are provided to support the respective end intake rocker arms 231e and end exhaust rocker arms 232e for the cylinders provided at the left and right ends of the cylinder head 201. These cam carriers 223el, 223er are each formed generally in the same shape as the middle cam carriers 223m but are shorter and less complex in some regards because they each only journal one intake rocker arm 231e and one exhaust rocker arm 232e. Furthermore and as best seen in FIG. 14, the respective rocker shafts 224e and 234e are shorter in length than the rocker shafts 224 and 234 of the middle cam carriers since they only carry one rocker arm.

[0072] Since the end cam carriers 223el and 223er journal respective ends of the camshafts 24 and 25 they are each provided with respective upper pieces 223eib and 223eeb that are fixed in place by the fasteners 227 in the manner as discussed with the other embodiments.

[0073] The lubrication system associated with the end cam carriers 223el and 223er is generally the same as that for the middle cam carriers and their associated components, as shown in FIG. 14, except for the fact that it is only for two valves rather than four valves and thus it will not be described again in detail, but like components are identified by like reference numerals.

[0074] In the multi-cylinder internal combustion engine of the previous embodiments the cam carriers have been associated respectively with a single cylinder. They have thus been centered over the axis of the associated cylinder bore of the cylinder block. Thus the collars 36 have passed through the central openings that receive them. Also, as has been noted, this affords the opportunity to use materials of different thermal expansion to assure retention. The same effect is obtained with this embodiment, as will now be described.

[0075] As described, the middle cam carriers 223m are each mounted between adjacent cylinders. In addition these middle cam carriers 223m have a length that is somewhat less than the distance between adjacent cylinder axes. Thus there is in fact a gap between adjacent ends of the middle cam carriers 223m. In addition there is a like gap between the end cam carriers 223el 223er and their adjacent middle cam carriers 223m. Thus the adjacent ends are formed with semi-cylindrical notches 241 that are complimentary to the lower portions of the cylindrical collars 36. Therefore, even in the multi-cylinder internal combustion engine 201 having an ignition plug 37 dispose above each cylinder, the cam carriers 223m can be configured such that they don't obstruct the disposition of ignition plugs 37. Thus, the degree of freedom in designing can be increased for the disposition of cam carriers 223m in the multi-cylinder internal combustion engine 201.

[0076] As has already been described in detail and thus to summarize, the connection between the collars 216, cylinder head 201 and various cam carriers 223m, 223el and 223er as well as the interengagement between the various rocker arm shafts and the fasteners maintains all of the components in their desired relationship and reduces the labor and machining to produce the engines, as described

[0077] Of course those skilled in the art will readily understand that the described embodiments are only exemplary of forms that the invention may take and that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.

Claims

1. A valve actuating mechanism for a reciprocating machine having a cylinder head adapted to be affixed in closing relation to at least one cylinder bore formed in a cylinder block, a cam shaft carrier affixed to said cylinder head and defining a cam shaft bore for journaling a bearing surface of a cam shaft, a rocker arm journal formed by said cam shaft carrier in parallel relation to said cam shaft bore and extending on at least one side of said cam shaft bore, and a rocker arm journalled by said rocker arm journal and having a follower surface engaged by a cam lobe of said cam shaft.

2. A valve actuating mechanism as set forth in claim 1 wherein a pair of rocker arm journals are formed by said cam shaft carrier, each of which journals a respective rocker arm.

3. A valve actuating mechanism as set forth in claim 2 wherein the pair of rocker arm journals formed by the cam shaft carrier are coaxial.

4. A valve actuating mechanism as set forth in claim 3 wherein the coaxial pair of rocker arm journals formed by said cam shaft carrier are disposed on opposite axial sides of the cam shaft bore.

5. A valve actuating mechanism as set forth in claim 2 wherein the pair of rocker arm journals formed by the cam shaft carrier are disposed on opposite sides of the cam shaft bore.

6. A valve actuating mechanism as set forth in claim 5 further including a second pair of rocker arm journals formed by the cam shaft carrier on opposite axial sides of the cam shaft bore to receive and journal a total of four rocker arms.

7. A valve actuating mechanism as set forth in claim 1 wherein the cylinder head closes a plurality of parallel, axially spaced cylinder bores of an associated cylinder block and respective cam shaft carriers are associated with the cylinder bores.

8. A valve actuating mechanism as set forth in claim 7 wherein a pair of rocker arm journals are formed by each of the cam shaft carriers, each of said journals journaling a respective rocker arm.

9. A valve actuating mechanism as set forth in claim 8 wherein the respective rocker arms operate valves associated with the same cylinder closed by the cylinder head.

10. A valve actuating mechanism as set forth in claim 9 wherein the valves operated by the rocker arms are both intake or exhaust valves.

11. A valve actuating mechanism as set forth in claim 9 wherein one of the valves operated by one of the rocker arms is an intake valve and the other rocker arm operates an exhaust valves.

12. A valve actuating mechanism as set forth in claim 2 wherein the pair of rocker arm journals formed by the cam shaft carrier are parallel.

13. A valve actuating mechanism as set forth in claim 3 wherein the parallel pair of rocker arm journals formed by said the shaft carrier are disposed on opposite axial sides of the cam shaft bore.

14. A valve actuating mechanism as set forth in claim 2 wherein the pair of rocker arm journals formed by the cam shaft carrier are disposed on opposite sides of the cam shaft bore.

15. A valve actuating mechanism as set forth in claim 5 further including a second pair of rocker arm journals formed by the cam shaft carrier on opposite axial sides of the cam shaft bore to receive and journal a total of four rocker arms.

16. A valve actuating mechanism as set forth in claim 15 further including slots formed in the cam shaft carrier for retaining respective of the journalled rocker arms.

17. A valve actuating mechanism as set forth in claim 16 further including pivot shafts for pivotally supporting pairs of said rocker arms on the respective opposite axial sides.

18. A valve actuating mechanism as set forth in claim 9 wherein there are spark plug receiving openings formed by the cylinder head each generally aligned with the axis of the respective cylinder bore and further including a plurality of spark plug receiving collars affixed to the cylinder head for receiving respective ones of said spark plugs.

19. A valve actuating mechanism as set forth in claim 18 wherein the collars each cooperate with a respective one of the cam carriers for fixing their positions relative to the cylinder head.

20. A valve actuating mechanism as set forth in claim 19 wherein the coefficients of thermal expansion of the collars and cam carriers are different to effect interlocking therebetween under operating conditions.