VALVE OPERATING APPARATUS IN AN INTERNAL COMBUSTION ENGINE

Abstract: Valve operating apparatus is disclosed in which the valves (la,lb) are operated by rocker arms (7,8,9) driven by cams (3,4,5) having different cam profiles and hydraulically operated coupling mechanisms (2l,22) for selectively connecting or disconnecting adjacent rocker arms to vary the operation of the valves under different engine operating conditions. The coupling mechanisms are operated by fluid supplied through the rocker shaft (6) mounting the roker arms. The rocker shaft is divided into independent fluid supply passages (32,33) whereby the couplings can be supplied independently with operating fluid in order to expand the number of available valve operating control modes. Variations are described in which operating fluid can be independently supplied to various auxillary hydraulically-operated equipment, as well as to the selective coupling mechanisms.

Description: The present invention relates to valve operating apparatus in an internal combustion engine. More particularly, the invention involves valve operating apparatus of the type including a camshaft rotatably driven by the engine, a plurality of cams on the camshaft for operating the intake or exhaust valves according to a selected mode of operation, and pivotably mounted rocker arms for opening and closing the valves in response to rotation of the cams. In valve operating devices of the type described, driver rocker arms operably connected to the valve or valves to be operated, and free rocker arms, independent of the valves, are disposed adjacent each other and are operable in different modes by rotation of the cams. A selective coupling carried by the rocker arms is hydraulically actuable for selectively interconnecting or disconnecting the respective rocker arms according to the desired mode of valve operation. In such valve operating devices, it is general practice to select relative valve diameters, valve timings, and valve lifts in view of a high-speed range for higher engine output power. However, if an intake valve is actuated at constant valve timing and valve lift throughout a full engine speed range from low to high speeds, then the speed of flow of an air-fuel mixture into the combustion chamber varies from engine speed to engine speed since the amount of air-fuel mixture introduced per unit time varies from engine speed to engine speed. At low engine speeds, the speed of flow of the air-fuel mixture is lowered, the charging efficiency is lowered, and the air-fuel mixture is not mixed and atomized appropriately in the combustion chamber, resulting in slow combustion therein. Therefore, no stable combustion is achieved, and the engine speed becomes irregular during the low-speed operation. Consequently, the combustion efficiency, the fuel economy, and the knocking margin are all reduced. One solution to the above problem is suggested in Japanese Laid-Open Patent Publication No. 59-226216. According to that solution, some of the intake and/or exhaust valves remain closed when the engine operates at a low speed, whereas all of the intake and exhaust valves are operated, i.e., alternately opened and closed, during high-speed operation of the engine. Controlling the valve differently in low- and high-speed ranges, as suggested by this reference, is not totally dispositive of the problem, however. For example, if the valve control were effected in different modes in more speed ranges, the engine output power would be increased, stable low-speed operation would become possible, and the fuel economy would be improved. In the above-referred prior art valve operating device, moreover, hydraulic passages for supplying hydraulic pressure respectively to the selective coupling means are defined by dividing the inner space of the rocker shaft by means of a steel ball that is forcibly inserted into and securely positioned in the rocker shaft. With such a structure, the hydraulic pressure must be supplied from the axially opposite sides of the rocker shaft, and hence the hydraulic pressure supply circuit for the valve operating device for use in a multicylinder internal combustion engine becomes complex. It is known from JP-A-61 81510 to provide, in an internal combustion engine having intake and exhaust valves, selective valve operating apparatus comprising: a rocker shaft having a hollow interior defining a fluid supply means; a plurality of rocker arms mounted for pivotal movement on said rocker shaft, said rocker arms including at least one driver rocker arm having an end operably connecting one of said valves; a cam shaft rotatably driven by said engine; cam means mounted on said cam shaft for rotation therewith and operably engaging a rocker arm follower surface; hydraulically operated, selectively actuable coupling means carried by said rocker arms for selectively connecting or disconnecting adjacent rocker arms; a hydraulic lash adjuster operably connecting said driver rocker arm to its associated valve; and fluid supply passages through said rocker arms communicating at one end with said fluid supply means in said rocker shaft and at the other end with said coupling means and said lash adjuster, respectively. In the known arrangement there are two valves either operated together according to the profile of a single cam, or one of the valves is operated by the cam and the other remains closed. The present invention is characterised in that the cam means comprises a plurality of cams each with a profile for causing valve opening and all the rocker arms have a cam follower surface engaged by a respective cam. Thus the present invention may provide valve operating means in an internal combustion engine in which valves are controlled in a multitude of speed ranges by a simplified hydraulic pressure supply circuit. The invention contemplates selectively actuable coupling means disposed between adjacent ones of the rocker arms for interconnecting and disconnecting the rocker arms. According to one particularly beneficial embodiment, the valve operating device employs a camshaft having three adjacent cams. Three pivotally mounted rocker arms are held in sliding contact with the respective cams, one of the rocker arms being a free rocker arm and the other two being driver rocker arms operably connected to the intake or exhaust valves for opening and closing them. The selective coupling means between adjacent rocker arms are each independently supplied with operating fluid so that a greater number of engine speed ranges can be controlled. In a preferred embodiment, the rocker shaft is divided by axially extending partitions into a plurality of hydraulic pressure supply passages for separate communication with the respective coupling means. By separately and selectively actuating the respective coupling means in accordance with the operating conditions of the engine, the rocker arms can be operated in different modes, and the valves can be controlled in a large number of speed ranges. The required hydraulic pressure control circuit is simplified because the hydraulic supply passages defined in the rocker shaft by the axially extending partitions communicate separately with the respective coupling means. Moreover, as a result of the provision of separate, independent hydraulic pressure supply passages, the supply of operating fluid for other than selective coupling operation can readily be accommodated. In this regard, the present invention also contemplates, in related embodiments, the independent supply of operating fluid; for example, to plural hydraulic lash adjusters each employed between a respective driver rocker arm and the associated valve. In addition, fluid, such as oil, for lubricating various parts of the apparatus can also be provided. Reference will now be made to the accompanying drawings, in which Figures 1 to 8 show valve operating apparatus not in accordance with the present invention but included herein to assist understanding of Figures 9 and 10 which show preferred embodiments of the invention. In the drawings: Figure 1 is an elevational view of valve operating apparatus taken along line I-I of Figure 2; Figure 2 is a plan view of the valve operating apparatus of Figure 1; Figure 3 is a sectional view taken along line III-III of Figure 1; Figures 4, 5 and 6 are sectional views taken along line IV-IV of Figure 1 illustrating the selective coupling means in various operating conditions; Figures 7 and 8 are sectional views similar to Figure 4 illustrating additional arrangements of selective coupling means; Figure 9 is a sectional elevational view of a valve operating apparatus of the present invention in which a hydraulic adjuster is incorporated; and Figure 10 is a view similar to Figure 9 illustrating the further incorporation of lubrication means. In Figures 1 and 2, which show a first valve operating apparatus, a pair of intake valves 1a, 1b are disposed in the body of an internal combustion engine. The valves 1a, 1b can be opened and closed by a first low-speed cam 3, a second low-speed cam 4, and a high-speed cam 5 which are integrally formed on a camshaft 2 rotatable in synchronism with rotation of the engine at a speed ratio of 1/2 with respect to the speed of rotation of the engine. The cams 3, 4, 5 operate first, second and third rocker arms 7, 8, 9 pivotally supported on a rocker shaft 6 extending parallel to the camshaft 2. The camshaft 2 is rotatably disposed above the engine body. The high-speed cam 5 is integrally formed on the camshaft 2 in alignment with an intermediate position between the intake valves 1a, 1b. The first low-speed cam 3 has a cam profile to meet low-speed operation of the engine and includes a cam lobe 3a projecting radially outwardly to a relatively small extent. The high-speed cam 5 has a cam profile to meet high-speed operation of the engine and includes a cam lobe 5a projecting radially outwardly to a greater extent than the cam lobe 3a, the cam lobe 5a also having a larger angular extent than the cam lobe 3a. The second low-speed cam 4 also has a cam profile to meet the low-speed operation of the engine and includes a cam lobe 4a projecting radially outwardly to a relatively small extent, the cam lobe 4a being smaller than the cam lobe 3a. The rocker shaft 6 is fixed below the camshaft 2. The first through third rocker arms, 7 through 9, which are operated respectively by the high-speed cam 5, the first low-speed cam 3, and the second low-speed cam 4, are pivotally supported on the rocker shaft 6. The rocker arms 7, 8, 9, have on their upper portions cam slippers 7a, 8a, 9a, held in sliding contact with the cams, 3, 4, 5, respectively. The second and third rocker arms, 8, 9, extend to positions above the intake valves 1a, 1b. Tappet screws 12, 13 are threaded through distal ends of the second and third rocker arms 8, 9 and are engageable with the upper ends of the intake valves 1a, 1b. Flanges 14, 15 are attached to the upper ends of the intake valves 1a, 1b. The intake valves 1a, 1b are normally urged upward, i.e., in a closing direction, by compression coil springs 16, 17 disposed on the intake valves 1a, 1b between the flanges 14, 15 and the engine body. As shown in Figure 3, a cylindrical lifter 19 having a closed upper end is disposed as a pushing means in abutment against a lower surface of the end of the first rocker arm 7. The lifter 19 is normally urged upwardly by a lifter spring 20 of relatively weak resiliency interposed between the lifter 19 and the engine body (not shown) for resiliently biasing the cam slipper 7a of the first rocker arm 7 slidably against the high-speed cam 5. As illustrated in Figure 4, the first and second rocker arms 7, 8 are disposed in laterally adjacent sliding contact with each other. A first selectively actuated coupling 21 is operatively disposed between the first and second rocker arms 7, 8 for selectively disconnecting the rocker arms 7, 8 from each other for relative angular displacement and also for interconnecting the rocker arms 7, 8 for their movement in unison. Likewise, the first and third rocker arms 7, 9 are disposed in laterally adjacent sliding contact with each other. A second selectively actuated coupling 22 is operatively disposed between the first and third rocker arms 7, 9 for selectively disconnecting the rocker arms 7, 9 from each other for relative angular displacement and also for interconnecting the rocker arms 7, 9 for their movement in unison. The first and second selectively actuated couplings 21, 22 are of an identical construction, and hence only the first coupling 21 will hereinafter be described in detail. The first coupling 21 comprises a piston 23 movable between a position in which it interconnects the first and second rocker arms 7, 8 and a position in which it disconnects the first and second rocker arms 7, 8 from each other. Also provided are a stopper 24 for limiting the movement of the piston 23, and a spring 25 for urging the stopper 24 to move the piston 23 toward the position to disconnect the first and second rocker arms 7 and 8 from each other. The first rocker arm 7 has a first guide hole 26 opening toward the second rocker arm 8 and extending parallel to the rocker shaft 6. The first rocker arm 7 also has a smaller-diameter hole 28 near the closed end of the first guide hole 26 with a step 27 being defined between the smaller-diameter hole 28 and the first guide hole 26. The piston 23 is slidably fitted in the first guide hole 26. The piston 23 and the closed end of the smaller-diameter hole 28 cooperate to define therebetween a hydraulic pressure chamber 29. The second rocker arm 8 has a second guide hole 35 opening toward the first rocker arm 7 for registration with the first guide hole 26 in the first rocker arm 7. The circular stopper 24 is slidably fitted in the second guide hole 35. The second rocker arm 8 also has a smaller-diameter hole 37 near the closed end of the second guide hole 35 with a step 36 defined between the second guide hole 35 and the smaller-diameter hole 37 for limiting movement of the circular stopper 24. The second rocker arm 8 also has a through-hole 38 defined coaxially with the smaller-diameter hole 37. A guide rod 39 joined integrally and coaxially to the circular stopper 24 extends through the hole 38. A coil spring 25 is disposed around the guide rod 39 between the stopper 24 and the closed end of the smaller-diameter hole 37. The piston 23 has an axial length selected such that, when one end of the piston 23 abuts against the step 27, the other end thereof is positioned at the interface between the first and second rocker arms 7, 8, and, when the piston 23 is moved into the second guide hole 35 until it displaces the stopper 24 into abutment against the step 36, the said one end of the piston 23 remains in the first guide hole 26. The rocker shaft 6 has an axially extending partition 31 forced or fixedly mounted therein or it may be integrally formed therewith. The partition 31 divides the inner space of the rocker shaft 6 into two longitudinally parallel, hydraulic pressure supply passages 32, 33. The first rocker arm 7 has adjacent one end a hydraulic passage 34 defined therein in communication with the hydraulic pressure chamber 29 of the first coupling 21. The rocker shaft 6 has a hole 40 defined therein and providing communication between the hydraulic passage 34 and the hydraulic passage supply passage 32 irrespective of how the first rocker arm 7 is angularly moved about the rocker shaft 6. The first rocker arm 7 has adjacent to its other end an annular groove 41 surrounding the rocker shaft 6 and a hydraulic passage 42 through which the annular groove 41 communicates with the hydraulic pressure chamber 29 of the second coupling 22. The rocker shaft 6 has a hole 43 providing communication between the hydraulic pressure supply passage 33 and the annular groove 41. Therefore, the hydraulic pressure chamber 29 of the first coupling 21 communicates with the hydraulic pressure supply passage 32, and the hydraulic pressure chamber 29 of the second coupling 22 communicates with the hydraulic pressure supply passage 33. The first and second couplings 21, 22 can thus be operated independently of each other. Operation of the valve operating mechanism is as follows. When the engine is to operate in a low-speed range, the first and second couplings 21, 22 are actuated to disconnect the first through third rocker arms 7, 8, 9 from each other as illustrated in Figure 4. More specfically, hydraulic pressure is released from the hydraulic pressure chamber 29, thus allowing the stopper 24 to move toward the first rocker arm 7 under the resiliency of the spring 25 until the piston 23 abuts against the step 27. In this condition, the mutually contacting ends of the piston 23 and the stopper 24 of the first coupling 21 are aligned with the adjacent, mutually sliding side walls of the first and second rocker arms 7, 8, and the mutually contacting ends of the piston 23 and the stopper 24 of the second coupling 22 are aligned with the adjacent, mutually sliding side walls of the first and third rocker arms 7, 9. Thus, the first, second, and third rocker arms, 7, 8, 9 are held in mutually side-by-side sliding contact for relative angular movement. With the first through third rocker arms 7, 8, 9 being thus disconnected, the second and third rocker arms, 8, 9 are not affected by the angular movement of the first rocker arm 7. The second rocker arm 8 is angularly moved in sliding contact with the first low-speed cam 4, whereas the third rocker arm 9 is angularly moved in sliding contact with the second low-speed cam 5. Therefore, the intake valve 1a is alternately opened and closed by the second rocker arm 8, and the other intake valve 1b is alternately opened and closed by the third rocker arm 9. Any frictional loss of the valve operating mechanism is relatively low because the first rocker arm 7 is held in sliding contact with the high-speed cam 5 under the relatively small resilient force of the lifter spring 20. During low-speed operation of the engine, therefore, the intake valve 1a is alternately opened and closed at the valve timing and valve lift according to the profile of the first low-speed cam 3, whereas the other intake valve 1b is alternately opened and closed at the valve timing and valve lift according to the profile of the second low-speed cam 4. Accordingly, the air-fuel mixture flows into the combustion chamber at a rate suitable for the low-speed operation of the engine, thereby resulting in stable fuel combustion, improved fuel economy, stable low-speed operation, and prevention of knocking. Since the profiles of the low-speed cams 3, 4 are different, the turbulence of the air-fuel mixture in the combustion chamber is increased for improved fuel economy. For medium-speed operation of the engine, the first and second rocker arms 7, 8 are interconnected by the first coupling 21, with the first and third rocker arms 7, 9 remaining disconnected from each other, as shown in Figure 5. More specifically, the hydraulic pressure chamber 29 of the first coupling 21 is supplied with hydraulic pressure from the hydraulic pressure passage 32 to cause the piston 23 to push the stopper 24 into the second guide hole 35 against the resiliency of the spring 25 until the stopper 24 engages the step 36. The first and second rocker arms 7, 8 are now prevented from relative angular movement, but, instead, are caused to swing in unison. Therefore, the intake valve 1a is alternately opened and closed at the valve timing and valve lift according to the profile of the high-speed cam 5, whereas the other intake valve 1b is alternately opened and closed at the valve timing and valve lift according to the profile of the second low-speed cam 4. The air-fuel mixture now flows into the combustion chamber at a rate suitable for the medium-speed operation of the engine, resulting in a relatively high charging efficiency and greater turbulence of the air-fuel mixture in the combustion chamber and hence an improved fuel economy, as with the low-speed operation. When the engine is to operate at a high speed, the first and third rocker arms 7, 9 are interconnected by the second coupling 22, as shown in Figure 6, by supplying hydraulic pressure into the hydraulic pressure chamber 29 of the second coupling 22. Inasmuch as the first and second rocker arms 7, 8 remain connected by the first coupling 21 at this time, the rocker arms 7, 8, 9 are caused to swing by the high-speed cam 5. As a consequence, the intake valves 1a, 1b are alternately opened and closed at the valve timing and valve lift according to the profile of the high-speed cam 5. The charging efficiency is increased to enable the engine to produce high output power and torque. The inner space of the rocker shaft 6 is divided into the hydraulic pressure supply passages 32, 33 by the axially extending partition 31, and the hydraulic pressure supply passages 32, 33 are held in communication with the hydraulic pressure chambers 29 of the respective first and second couplings 21, 22. Therefore, the hydraulic pressure can be supplied from one axial end of the rocker shaft 6, thereby making the hydraulic pressure supply circuit simple in a valve operating device in a multicylinder internal combustion engine. As a modification of the first valve operating apparatus, the first and third rocker arms 7, 9 may be interconnected, while the first and second rocker arms 7, 8 are disconnected during the medium-speed operation of the engine. With such an arrangement, the intake valve 1a is alternately opened and closed at the valve timing and valve lift according to the profile of the first low-speed cam 3, whereas the other intake valve 1b is alternately opened and closed at the valve timing and valve lift according to the profile of the high-speed cam 5. Figure 7 shows a second valve operating apparatus. In this apparatus a piston 23' is slidably disposed in each of the second and third rocker arms 8, 9, and stoppers 24' are slidably disposed in the first rocker arm 7 for urging stoppers 24 toward the pistons 23'. The second and third rocker arms 8, 9 have hydraulic passages 34, 42 providing communication between the hydraulic pressure supply passages 32, 33 and the hydraulic pressure chambers 29 of the selective couplings 21', 22'. In addition to the advantages of the first apparatus, in this apparatus any malfunctions due to hydraulic pressure leakage can be prevented with the hydraulic pressure chambers 29 being provided in the second and third rocker arms 8, 9. Figure 8 illustrates a third apparatus in which the first coupling 21 is disposed between the first and second rocker arms 7, 8, and the second coupling 22' is disposed between the first and third rocker arms 7, 9. The third apparatus is as advantageous as the second apparatus. Figure 9 illustrates a first preferred embodiment of the present invention. In this embodiment, the second and third rocker arms 8', 9' are held against the intake valves 1a, 1b, respectively, through hydraulic tappets T1, T2. The rocker shaft 6 has therein an axially extending partition 45 of a Y-shaped cross section forced or fixedly mounted therein or integrally formed therewith. The partition 45 divides the inner space of the rocker shaft 6 into three parallel hydraulic pressure supply passages 46, 33, 32. The second and third rocker arms 8', 9' have respective hydraulic passages 49 for supplying hydraulic pressure to the respective hydraulic tappets T1, T2. The rocker shaft 6 has a hole 50 defined therein for providing communication between the hydraulic passages 49 and the hydraulic pressure supply passage 46. A rocker arm (not shown) disposed between the second and third rocker arms 8', 9' has annular grooves 51, 41 surrounding the rocker shaft 6 in a position corresponding to the couplings 21, 22 and also has hydraulic passages 34, 42 through which the hydraulic pressure chambers of the couplings 21, 22 communicate respectively with the annular grooves 51, 41. The rocker shaft 6 also has a hole 53 communicating between the hydraulic pressure supply passage 33 and the annular groove 51 and a hole 40 communicating between the hydraulic pressure supply passage 32 and the annular groove 41. According to the first preferred embodiment, the hydraulic tappets T1, T2, the coupling 21, and the coupling 22 can individually be supplied with hydraulic pressure, and the hydraulic pressure circuit is not complicated. Figure 10 shows a second preferred embodiment of the present invention. In this embodiment, the rocker shaft 6 has an axially extending partition 60 of an X-shaped cross section forced or fixedly mounted therein or integrally formed therewith. The partition 60 divides the inner space of the rocker shaft 6 into four parallel hydraulic pressure supply passages 46, 33, 32, 59. As with the first embodiment, the hydraulic pressure supply passages 46, 33, 32 communicate with the respective hydraulic pressure chambers of the hydraulic tappets T1, T2, and with the couplings 21, 22. The hydraulic pressure supply passage 59 communicates with a hydraulic passage 58 for supplying lubricating oil to the cam slippers and a separate hydraulic passage (not shown) for supplying lubricating oil to the cam journals. For this purpose, a hole 57 defined in the rocker shaft 6 is caused to connect annular grooves 61 defined in the respective rocker arms 7, 8', 9' with the hydraulic pressure supply passage 59. In addition to the advantages of the first embodiment, the second embodiment has an additional advantage in that lubricating oil can be supplied to the slidingly contacting surfaces of the cams 3, 4, 5, to the rocker arms 7, 8', 9' and also to the cam journals through a simple hydraulic passage arrangement. According to the present embodiments, therefore, selectively actuated couplings are disposed between mutually adjacent rocker arms for interconnecting and disconnecting them. The couplings are operable independently of each other by receiving operating fluid from separate sources of hydraulic pressure. Therefore, the entire operation range of an engine can be divided into three or more ranges for valve operation control to achieve increased engine output power and fuel economy. Moreover, as shown in the described embodiments of the invention, first and second hydraulic passages can be provided for any number of valves and any particular arrangement of rocker arms and selectively actuated couplings, which may vary from control mode to control mode. Two second hydraulic passages can independently be provided in order to allow three-mode control. Since, in the preferred embodiments, a plurality of hydraulic pressure passages communicating separately with the respective selective couplings are defined by an axially extending partition in the rocker shaft, the hydraulic pressure supply system, even one used in a multicylinder internal combustion engine, can be simplified. Additionally, the number of separate hydraulic pressure passages can be selected so as to additionally provide operating fluid to the hydraulic lash adjusters and oil to lubricate the operating parts of the apparatus. While the present invention has been described with respect to intake valves in the aforesaid embodiments, it will be appreciated that the invention is equally applicable to the operation of exhaust valves. It is also possible to change variable valve timing in a plurality of modes with a single intake or exhaust valve, without any limitation on the control modes and the number of valves.

Claims: In an internal combustion engine having intake and exhaust valves (1a,1b), selective valve operating apparatus comprising: a rocker shaft (6) having a hollow interior defining a fluid supply means (32,33,46,59); a plurality of rocker arms (7,8',9') mounted for pivotal movement on said rocker shaft (6), said rocker arms including at least one driver rocker arm (8',9') having an end operably connecting one of said valves (1a,1b); a cam shaft (2) rotatably driven by said engine; cam means (3,4,5) mounted on said cam shaft (2) for rotation therewith and operably engaging a rocker arm follower surface; hydraulically operated, selectively actuable coupling means (21,22) carried by said rocker arms for selectively connecting or disconnecting adjacent rocker arms (7,8',9'); a hydraulic lash adjuster (T1,T2) operably connecting said driver rocker arm (8',9') to its associated valve (1a,1b); and fluid supply passages (34,42,49) through said rocker arms communicating at one end with said fluid supply means (32,33,46,59) in said rocker shaft (6) and at the other end with said coupling means (21,22) and said lash adjuster (T1,T2), respectively; characterised in that the cam means comprises a plurality of cams (3,4,5) each with a profile for causing valve opening and all the rocker arms (7,8',9') have a cam follower surface engaged by a respective cam. Apparatus as claimed in claim 1, including lubricating fluid supply passages (58) in said rocker arms (7,8',9') for conducting lubricating fluid to said follower surface; and means (57,61) for connecting said lubricating fluid supply passages (58) to said fluid supply means (59). Apparatus as claimed in claim 1 or 2, in which said rocker arms include a free rocker arm (7) interposed between a pair of driver rocker arms (8',9') and said coupling means (21,22) includes couplers (23) for selectively connecting said free rocker arm to each adjacent driver rocker arm. Apparatus as claimed in claim 3, in which said coupling means (21,22) comprises a pair of couplers (23) oppositely disposed in said free rocker arm (7) for selective connection with the adjacent driver rocker arms (8',9'). Apparatus as claimed in claim 1, in which said lash adjuster (T1,T2) is disposed on said driver rocker arm (8',9') on the side of said rocker shaft opposite said follower surface. Apparatus as claimed in any preceding claim, including a flow restriction in the fluid supply passage (49) between said lash adjuster (T1,T2) and said rocker shaft fluid supply means (46). Apparatus as claimed in claim 1, wherein the rocker shaft (6) is provided with partition means (45,60) whereby the fluid supply means comprises a plurality of independent fluid supply lines (32,33,46,59), and there being means (40,41,49,50,51,53,57,61) for independently connecting respective ones of said fluid supply lines (32,33,46,59) to respective ones of said rocker arm fluid supply passages (34,42,49). Apparatus as claimed in claim 7, including a pair of hydraulic lash adjusters (T1,T2) each operably connecting a respective one of a pair of driver rocker arms (8',9') to the associated valve (1a,1b); fluid supply passages (49) through said driver rocker arms connecting with said lash adjusters; and means (50) for connecting one said rocker shaft fluid supply line (46) to said rocker arm lash adjuster fluid supply passages (49). Apparatus as claimed in claim 7, including lubricating fluid supply passages (58) in said rocker arms (7,8',9') for conducting lubricating oil to the cam follower surface thereof; and means (57,61) for connecting said lubricating fluid supply passages (58) to one of said rocker shaft fluid supply lines (59). Apparatus as claimed in claim 7, in which said rocker arms include a free rocker arm (7) interposed between a pair of driver rocker arms (8',9'), said coupling means (21,22) including independent couplers (23) for selectively connecting said free rocker arm to each adjacent driver rocker arm, and means (40,41,51,53) for independently connecting the fluid passages (34,42) in said rocker arms between respective ones of said rocker shaft supply lines (32,33) and each said coupler (23). Apparatus as claimed in claim 10, in which said coupling means (21,22) comprises a pair of couplers (23) oppositely disposed in said free rocker arm (7) for selective connection with an adjacent driver rocker arm (8',9'). Apparatus as claimed in claim 10, in which said coupling means (21,22) comprises a coupler (23) in each said driver rocker arm (8',9') for selective connection with said free rocker arm (7). Apparatus as claimed in claim 8, in which said rocker arms include a free rocker arm (7) interposed between a pair of driver rocker arms (8',9'); said coupling means (21,22) including separate couplers (23) for selectively connecting said free rocker arm to an adjacent driver rocker arm; said rocker arm fluid supply passages including first passages (34,42) connecting with said couplers (23) and second passages (49) connecting with said lash adjusters (T1,T2); and means (40,41,51,53) for connecting said first and second passages to respective ones of said rocker shaft supply lines (32,33). Apparatus as claimed in claim 7, including a rocker arm (8',9') having a rocker base pivotally mounted to said rocker shaft (6); an annular groove (41,51,61) in said rocker base communicating with a respective rocker arm fluid supply passage (32,42,49); and means (40,53,57) for communicating said annular groove (41,51,61) with one of said rocker shaft fluid supply lines (32,33,59). Apparatus as claimed in claim 7, 8, or 9, in which said rocker shaft fluid lines (32,33,46,59) conduct fluids at different pressures. Apparatus as claimed in any of claims 7 to 15, in which each of said cams (3,4,5) has a cam profile defining a different mode of valve operation and said coupling means (21,22) being selectively actuable in accordance with a desired mode of valve operation. In an internal combustion engine having two intake or two exhaust valves (1a,1b), apparatus as claimed in claim 1, the apparatus further comprising a pair of low speed cams (3,4) and a high speed cam (5) located between the low speed cams, a pair of first rocker arms (8',9') driven by said low speed cams respectively and each having a portion engaged with one of said valves (1a,1b), a second rocker arm (7) having a bore (26) therein and driven by said high speed cam (5) and located between said first rocker arms (8',9'), a pair of fluid pressure chamber means (29) formed in said second rocker arm (7), a pair of plunger means (23) each being provided in one of said fluid pressure chamber means (29), two bores (35) each being formed engageably with one of said plunger means (23) in each of said first rocker arms (8',9'), fluid passage means (34,42) formed in said second rocker arm (7) and communicated with said two fluid pressure chamber means (29), control means for controlling fluid pressure fed to said fluid passage means (34,42) in accordance with engine operating conditions, and a pair of hydraulic lash adjusters (T1,T2) each for adjusting lash between the end of each said first rocker arm (8',9') and the respective valve (1a,1b) engaged therewith, a said fluid supply passage (49) being formed in each said first rocker arm for feeding fluid to the lash adjusters.

Inventors: KONNO, TSUNEO C/O KABUSHIKI KAISHA
Applicants: HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: F01L31
IPC codes: F02D13, F01M9, F02F1, F01M11, F01L1