VARIABLE PHASE MECHANISM

Abstract

A yoke-type phaser is disclosed having a drive member and a driven member rotatable about a common axis and coupled to one another by means of a yoke that is movable, in a plane normal to the common axis, to vary the relative phase of the drive and driven members, by interaction between at least two contact elements and a contoured surface, one of (i) the contact elements and (ii) the contoured surface being connected for rotation with the drive member and the other being mounted on the yoke, each contact element comprising a roller in surface contact with a part-cylindrical recess in a carrier, wherein the carrier of at least one of the contact elements is either appropriately sized or adjustably mounted, to set the clearances between the rollers and the contoured surface.

Claims

1. A yoke-type phaser having a drive member and a driven member rotatable about a common axis and coupled to one another by means of a yoke that is movable, in a plane normal to the common axis, to vary the relative phase of the driven member relative to the drive member, by interaction between at least two contact elements and a contoured surface, one of the contact elements and the contoured surface being connected for rotation with the drive member and the other being mounted on the yoke, each contact element comprising a roller in surface contact with a part-cylindrical recess in a carrier; wherein the carrier of at least one of the contact elements is either appropriately sized, or adjustably mounted, to set the clearances between the rollers and the contoured surface.

2. A dual phaser for connecting a drive member to first and second driven members, all three members being rotatable about a common axis, wherein the drive member is connected to the first driven member by means of a first phaser and to the second driven member by means of a yoke-type phaser that comprises a yoke movable, in a plane normal to the common axis, to vary the phase of the second driven member relative to the drive member by interaction between at least two contact elements and a contoured surface, one of the contact elements and the contoured surface being defined by or mounted on the first driven member and the other being defined by or mounted on the yoke, each contact element comprising a roller in surface contact with a part-cylindrical recess in a carrier; wherein the carrier of at least one of the contact elements is either appropriately sized, or adjustably mounted, to set the clearances between the rollers and the contoured surface.

3. The dual phaser as claimed in claim 2, wherein the position of the carrier of at least one of the contact elements is adjustable by means of shims.

4. The phaser as claimed in claim 2, wherein the carrier of at least one of the contact elements is retained in position by means of a screw passing through an elongate slot in the carrier.

5. The dual phaser as claimed in claim 2, wherein the position of the carrier of at least one of the contact elements is adjustable by means of a hydraulic lash adjuster.

6. The dual phaser as claimed in claim 2, wherein each of the two phasers is provided with a respective bias spring to counteract resistive torques of the respective driven members.

7. The dual phaser as claimed in claim 2, wherein the first phaser is a vane-type phaser.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:

[0024] FIG. 1, as earlier described, shows an exploded view of a dual phaser know from EP2044297,

[0025] FIGS. 2a, 2b and 2c are earlier described sections through the dual phaser of FIG. 1,

[0026] FIG. 3 is a schematic view of two separate camshafts driven by means of a common dual phaser,

[0027] FIGS. 4 and 5 are exploded views similar to that of FIG. 1 showing two embodiments of the invention,

[0028] FIGS. 6 and 7 show detailed views of two further embodiments of the invention and,

[0029] FIG. 8 is a section through a detail of the embodiment of FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

[0030] The invention will be described below by reference to dual phasers driving two different sets of cam lobes. The dual phasers will be described as connected to an assembled camshaft, with one output member driving the inner shaft and the other the outer tube of the assembled camshaft. It should however be clear that all dual phasers may be used to drive two separate camshafts, as is schematically show in FIG. 3.

[0031] In FIG. 3, a vane-type phaser 300 has an output connected to a first camshaft 310. The vane-type phaser 300 has a second output connected to a yoke-type phaser 320 that in turn drives a gear 330 in mesh with a second gear 340 driving the second camshaft 350. Thus, in the prior art dual phaser of FIG. 1, instead of driving the bearing ring 118 that is connected to the outer tube of an assembled camshaft, it may be used to drive a gear of a gear train leading to a separate camshaft.

[0032] FIG. 4 of the drawings is an exploded view of a dual phaser of similar construction to the prior art dual phaser of FIG. 1 and, to simplify the description and help avoid repetition, components serving like functions in all the embodiments described below have been allocated reference numerals with the same last two significant digits.

[0033] The camshaft in FIG. 4 is an assembled camshaft comprising an inner shaft surrounded by an outer tube and having two sets of concentric cam lobes, one set being fast in rotation with the outer tube and the other set being rotatable relative to the outer tube and connected for rotation with the inner shaft by means of pin passing through circumferentially elongated slots in the outer tube. As with the dual phaser of FIG. 1, the dual phaser of FIG. 4 has a vane-type phaser driving one set of cam lobes and a yoke-type phaser driving the second set of cam lobes. The dual phaser of FIG. 4 differs from that shown in FIG. 1 in that the vane-type phaser is used to drive the outer tube of the assembled camshaft and the yoke-type phaser drives its inner shaft.

[0034] The input member 412 of the dual phaser in FIG. 4 is connected to a gear 414, rather than a sprocket, that is driven by the engine crankshaft. The input member has four arcuate cavities 422 each receiving a respective vane 420 that separates the cavity into two separate working chambers. Oil supplied to the working chambers through a spool valve 450 can move the vanes 420 tangentially from one end of the cavity to the other.

[0035] The vanes 420 are connected to two end plates 424 of which only one is seen in the drawing. The two end plates 424 seal the working chambers of the arcuate cavities 422 and serve as the output member of the first, vane-type, phaser. The output member of the vane-type phaser serves to drive the outer tube of the assembled camshaft to vary the phase of the first set of cam lobes relative to the crankshaft.

[0036] The inner shaft of the assembled camshaft is bolted to a tubular member 444 onto which a crank arm 460 is keyed. Rotation of the crank arm 460 about the axis of the camshaft serves to change the phase of the inner shaft of the camshaft relative to the engine crankshaft.

[0037] The crank arm 460 is connected to the yoke 428 by way of a fulcrum pin 435 and an eccentric sleeve 434 rotatably received in a hole 436. The diametrically opposite side of the yoke 428 is connected by a pivot pin 442 to the input member 412 of the dual phaser. Pivoting of the yoke 428 about the pin 442 causes the hole 436 to pivot about the axis of the pin 442 and thereby cause the crank arm 460 to rotate in order to change the phase of the inner shaft of the camshaft relative to the input member 412, the latter being driven directly by the engine crankshaft. The eccentric sleeve 434 is required because the distance of the pin 435 from the axis of rotation of the yoke changes as the yoke pivots about the pin 442.

[0038] The angular position of the yoke 428 relative to the input member 412 is dictated by the angular position of the end plate 424, serving as the output member of the vane-type phased. To this end, the end plate 424 includes two contact elements, generally designated 440, in contact with the contoured outer surface 428a of the yoke 428. In FIG. 4, one of the contact elements 440 is shown in an assembled state and the other in exploded view. The contact elements 440 each comprise a roller 447 journaled in, and making surface contact with, a part-cylindrical recess 451 in a carrier 441. The carrier 441 is secured to the end plate 424 by means of a screw 443 passing through a washer plate 445 and an elongate slot in the carrier 441. Pins 453 engaging in the end plate 424 and in elongate slots 455 in the carrier 441 ensure correct orientation of the carrier 441 while permitting adjustment of the distance of the roller 447 from the contoured surface 428a.

[0039] The journaled rollers 447 that engage the contoured surface 428a in FIG. 4 offer less frictional resistance than the pins 140 of the dual phaser of FIG. 1 and furthermore the adjustability of their position on the end plate 424 ensures that the clearance between the rollers 447 and the contoured surface 428a can be set accurately.

[0040] The dual phaser shown in FIG. 5 demonstrates that the members to which the contact elements and the contoured surface are connected are interchangeable. Thus, in FIG. 5 the contact elements 540 are carried by the yoke 528 and the contoured surface is an inwardly facing cam surface 570a of disc 570 secured to the end plate 524 of the vane-type phaser. The construction of the vane-type phaser is not shown in FIG. 5 but is the same as that in FIG. 4.

[0041] In this case, the roller 547 is journaled in, and makes surface contact with, a part-cylindrical recess 551 a carrier 541 that slides in a channel 555 in the yoke 528. The clearance in this embodiment is set by appropriate sizing of the carriers 541.

[0042] FIG. 5 also shows that the dual phaser may comprise two bias springs 582 and 584 to counteract resistive torques of the respective driven members. The spring 582 acts on the crank arm 560 by way of a plate 586 and hence on the output member of the yoke type phaser. By contrast, the spring 584 acts on a plate 590 carrying timing features and secured to the output member of the vane-type phaser.

[0043] FIG. 6 shows how a shim 661 may be disposed between one, or both, of the carriers 641 and the bottom of the channel 655 to set the clearances.

[0044] FIGS. 5, 6 and 7 also show an alternative connection between the yoke 628 and the crank arm 660 in that instead of an eccentric sleeve the fulcrum pin 635 is slidable on radial projection of the crank arm 660.

[0045] FIGS. 7 and 8 show a further embodiment of the invention in which a hydraulic lash adjuster 893 is used in place of a shim, the embodiment being otherwise the same as that of FIG. 6. Hydraulic lash adjusters are of course well known and rely on oil pressure to set a minimal clearance. FIG. 8 shows that an oil drilling may be provided in the yoke 828 for this purpose but lash adjusters are better suited to embodiments in which the contoured surface is on the perimeter of the yoke.