Abstract: An engine is described having two camshafts 14, 16 each of which carries two groups of cams and comprises an inner shaft coupled for rotation with a first group of cams and an outer tube rotatably supported by the inner shaft and coupled for rotation with the second group of cams. A phaser 12 is provided to enable the phase of at least one of the two groups of cams on one of the SAP camshafts 14, 16 to be varied with reference to the phase of the engine crankshaft. Drive links in the form of meshing gear wheels, drive chains or belts, couple the two corresponding groups of cams on the respective camshafts for rotation in unison with one another.

Abstract: A twin vane-type phaser is described which is provided with a locking mechanism for locking the drive member to the driven members when the pressure in the working chambers is a below is predetermined value. The locking mechanism comprises two coaxial locking pins 114, 118 mounted in a common bore 110 in the centrally located member 32. The locking pins are resiliently urged apart by a spring 120 into bores in the two outer members 38, 40 and are retracted by pistons 112, 116 when the hydraulic pressure in the working chambers attains the predetermined value.

Abstract: A valve operating mechanism is described for an internal combustion engine in which at least one valve (14) of an engine cylinder is operated by two cams (10,12). The cams (10,12) have respective cam followers (38,36) which are resiliently biased to remain in contact with the cams (10,12) at all times and which act on the valve (14) by way of a summation linkage (20,24) in such a manner that the displacement of the valve (14) at any instant is determined by a combination of the displacements of the two cam followers (38,36). In the invention, movement of each of the two cam followers (38,36) is transmitted to the summation linkage (20,24) by way of a respective one of two pushrods (28,30).

Abstract: An internal combustion engine is described having a valve mechanism which comprises a gas exchange poppet valve, a camshaft rotatable in synchronism with the engine crankshaft and having a cam for operating the valve, a valve actuator acting on the popper valve to open and close the valve, and an intermediate rocker having a follower acted upon by the cam and a contoured surface that acts on the valve actuator to open and close the valve in synchronism with the rotation of the cam, the intermediate rocker having a pivot axis that is movable in order to vary the valve lift.

Abstract: A hydraulic phase shifting mechanism is described for an engine camshaft subjected to torque fluctuations during operation. The mechanism employs a magnetorheological fluid as a hydraulic pressure medium and is controlled by selective application of a magnetic field to vary the flow properties of the magnetorheological fluid.

Abstract: A control system is disclosed for operating an engine valve. The system comprises two cams arranged on a common camshaft but rotatable relative to one another. A summation lever has cam followers in contact respective cams. The summation lever is movable in proportion to the instantaneous sum of the lifts of the respective cams. Rockers are provided for opening the engine valve in dependence upon the movement of the summation lever. By varying the phase of the cams relative to one another, it is possible to vary the valve timing, valve lift and/or valve event duration.

Abstract: An overhead camshaft internal combustion engine is disclosed having a valve mechanism which comprises an intake or exhaust poppet valve 14 having a valve stem operated by two cams 16 and 18 mounted for rotation about a common axis. A first rocker 20 mounted on a pivot shaft 26 acts between the first cam 16 and the valve 14. A second rocker 28 is mounted in the engine on a fixed pivot shaft 30 and acts between the second cam 18 and the pivot shaft 26 of the first rocker 20, to raise and lower the pivot point 26 of the first rocker 20 cyclically in synchronism with the rotation of the second cam 18.

Abstract: A variable camshaft assembly has a first cams 18a, 18b that can be moved relative to a second cam 16. The assembly comprising a tube 14 fast in rotation with the first cam 18 and rotatably supporting the second cam 16 and a drive shaft 12 disposed within the tube 14 and coupled for rotation with the second cam 16 by means of a connecting pin 20 that passes with clearance through a hole 24 in the tube 14. The connecting pin is a hollow pin 20 that is a sliding fit in the second cam 16 and that is expanded in situ to form an interference with the drive shaft 12.

Abstract: A variable phase drive mechanism is described for providing drive from an engine crankshaft to two sets of cams. The drive mechanism comprises a drive member 32 connectable for rotation with the engine crankshaft and two driven members 38 and 40, each connectable for rotation with a respective one of the two sets of cams. Each of the driven members 38, 40 is connected by a vane-type hydraulic coupling for rotation with the drive member 32. The hydraulic coupling between the drive and driven members is such as to enable the angular position of each of the driven members 38 and 40 to be varied relative to the drive member 32 independently of the other driven member.

Abstract: A phase change mechanism is disclosed for enabling the phase of an engine camshaft to be changed in relation to the engine crankshaft. The mechanism comprises a drive member connectable for rotation with the engine crankshaft, a driven member connectable for rotation with the engine camshaft and two oppositely acting one-way clutches for transmitting torque from the drive member to the driven member. In the invention, either one of the one-way clutches may be selectively disengaged at a time by hydraulically lifting a roller of its ramp surface to allow the drive member to slip relative to the driven member under the action of the periodic reversal of the reaction torque of the camshaft during engine operation.

Abstract: A valve actuating mechanism is disclosed which comprises a valve (12), a camshaft having a cam (22) of fixed profile associated with the valve (12), a valve lifting rocking cam (24) pivotable about a fixed axis and having a contoured surface that acts to open and close the valve (12) as the rocking cam (24) pivots about said fixed axis, and a cam following rocker (26) comprising a cam follower (46) in contact with the fixed profile cam (22) on the camshaft and coupled to the rocking cam (24) in order to cause the rocking cam (24) to pivot about the fixed pivot axis with rotation of the camshaft. The rocker (26) is pivotable about a second axis that is movable relative to the fixed pivot axis of the rocking cam (24) in such a manner as to allow the valve lift, phase and duration of the valve event to be varied in dependence upon the position of the pivot axis of the rocker (26).

Abstract: A phase change coupling is disclosed for allowing the angular position of a drive member 10 of a camshaft 12 to be varied in relation to the camshaft. The coupling is additionally provided with a locking mechanism for preventing rotation of the drive member relative to the camshaft in only one direction during cranking of the engine, so that, during cranking of the engine, the drive member 10 is rotated in only one sense relative to the camshaft by the camshaft torque reversals until it reaches a predetermined start-up angular position.

Abstract: In a phase change mechanism in which the phase of a driven member (10) relative to a drive member (12) is adjusted by axial displacement of an actuating rod (30) connected to the piston (50) of a hydraulic jack rotatable with the drive and driven members, the cylinder (52) of the hydraulic jack has a double-skinned wall, and the gap (54) between the two skins of the cylinder wall serves as a passage for supplying oil to and from one of the working chambers of the hydraulic jack.

Abstract: A variable phase mechanism comprises a hollow shaft 16, first 10 and second 14 members rotatable about the hollow shaft 16 and two yokes 18, 20 surrounding the hollow shaft 16, one yoke 18 coupling the hollow shaft 16 for rotation with first member 10 and the other yoke 20 coupling the second member 14 for rotation with the first member 10. An actuating rod 32 is slidably received in the hollow shaft 16, and has cam surfaces 36, 38 that on the first yoke 18 by way of a plungers 40 passing through a generally radial bore in the hollow shaft 16 to cause the first yoke 18 to move radially in response to axial movement of the actuating rod and thereby vary the angular position of the first member 10 relative to the hollow shaft 16. Rotation of the hollow shaft 16 relative to the first member 10 causes the outer surface of the hollow shaft 16 to interact with the inner surface of the second yoke 20 to cause the angular position of the second member 14 to be varied in relation to the first member 10.

Abstract: A variable phase coupling for connecting a crankshaft to a camshaft comprises a drive member for connection to the crankshaft having helical grooves of a first pitch, a driven member for connection to the engine camshaft having helical grooves of a different pitch facing towards the grooves in the drive member, an intermediate member disposed between the drive and driven members having helical grooves on its inner and outer surfaces, a first set of balls engaging in the pairs of helical grooves comprising the helical grooves in the driven member and the facing grooves on one surface of the intermediate member, a second set of balls engaging in the pairs of helical grooves that comprise the grooves in the drive member and the facing grooves on the other surface of the intermediate member, and means for axially displacing the intermediate member relative to the drive and driven members.

Abstract: A variable phase coupling 10 is disclosed for connecting a crankshaft of an engine to a camshaft 16. The coupling 10 comprises a drive member 14, 18 having a first set of grooves 20, a driven member 26 having a second set of grooves 28 and mounted in a fixed axial position relative to the drive member 18 and an intermediate member 30 movable axially in relation to the drive and driven members. Grooves are arranged on the same side of the intermediate member to face the grooves of both the drive member and the driven member. A first set of balls 36 is engaged in the grooves 20 of the drive member 18 and the intermediate member 30 and a second set of balls 34 is engaged in the grooves 28 of the driven member 26 and the intermediate member 30 so as to transmit torque from the drive member to the driven member through the intermediate member.

Abstract: An internal combustion engine is described having a crankshaft (14) and a camshaft, the ends of which project from a front end of the engine. A hydraulically operable variable valve actuation mechanism is mounted on the camshaft at the front end of the engine for driving the camshaft. A front cover (10) that overlies the end of the camshaft projecting from the front end of the engine, includes passages (40, 42) that are connected to supply oil under pressure from an engine driven pump (16) to the variable valve actuation mechanism.

Abstract: A variable phase coupling for connecting a crankshaft to a camshaft (12) comprises a drive member (20) for connection to the crankshaft having grooves (40) of a first pitch, a driven member (14) for connection to the engine camshaft (12) having helical grooves (26) of a different pitch facing towards the grooves (40) in the drive member (20), balls (28) engaged in the two helical grooves (26, 40) and serving to couple the drive and driven members for rotation with one another, an intermediate member (16) disposed between the drive and driven members for rotation with one another, an intermediate member (16) disposed between the drive and driven members in contact with the balls (28, 34), and means (56) for displacing the intermediate member (16) relative to the drive and driven members. The displacement of the intermediate member (16) serves to move the balls relative to the helical grooves in the drive and driven members so as to vary the phase between the drive and driven members.

Abstract: A method is described for manufacturing a multi-component camshaft assembly having an internal mechanism for enabling relative angular movement of individual cams of the assembly. In the invention, the cam surfaces are machined after the individual components of the camshaft assembly have been assembled to one another.