CN117396667A

CN117396667A - Variable phase mechanism

Info

Publication number: CN117396667A
Application number: CN202280038513.4A
Authority: CN
Inventors: 马克·沃尔顿; 乔恩·阿斯皮诺尔; 凯尔·韦布; 罗伯特·利斯
Original assignee: Mechadyne International Ltd
Current assignee: Mechadyne International Ltd
Priority date: 2021-06-08
Filing date: 2022-06-07
Publication date: 2024-01-12
Also published as: WO2022258581A1; US20240271551A1; DE112022001979T5; EP4102035A1

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 a yoke movable in a plane perpendicular to the common axis to change the relative phase of the drive member and driven member by interaction between at least two contact elements and a wave surface, wherein (i) one of the at least two contact elements and (ii) the wave surface is connected for rotation with the drive member and the other is mounted on the yoke, each contact element comprising a roller in contact with a part-cylindrical recess surface in a carrier, wherein the carrier of at least one of the at least two contact elements is suitably sized or adjustably mounted to set a gap between the roller and the wave surface.

Description

Variable phase mechanism

Technical Field

The present invention relates to a variable phase mechanism, also known as a phaser, for use in the valve train of an internal combustion engine to allow for varying the crank angle at which the valves of the engine open and close.

Background

It is well known that valve timing has a significant impact on engine performance and that the optimal setting varies with engine operating conditions. In order to optimize performance under different operating conditions, it is necessary to be able to vary the valve timing.

Variable phase mechanisms are known which comprise a shaft, a sleeve journalled on the shaft and fixedly rotatable with the cam, a coupling yoke connected to the shaft by a first pivot pin and to the sleeve by a second pivot pin, and means for pivoting the yoke about the first pivot pin to effect a phase change between the shaft and the sleeve. Such a mechanism is referred to herein as a yoke phaser and examples are found in EP0733154 and EP 1030035.

EP2044297 describes a biphaser similar in construction to the embodiment of the invention described below. A dual phaser is a phaser with two output members driving two different sets of cam lobes that may be on separate camshafts or mounted on a commonly assembled camshaft and allows the phase of the two sets of cam lobes to be adjusted relative to the phase of the crankshaft. In the latter patent, as described below, a vane-type phaser drives one of two sets of cam lobes, while a yoke-type phaser drives the other set.

The present invention relates to an improvement of a yoke-type phaser and, although described below with reference to a dual phaser, it is equally applicable to a single phaser.

Fig. 1 of the accompanying drawings is derived from EP2044297 and is described below to explain the problem addressed by the present invention.

The bi-phaser 110 of fig. 1 has a drive member 112 to be coupled for rotation with the crankshaft by a chain engaging sprocket 114. The drive member 112 has a central bore 116 supported by a front bearing 118 of the camshaft. The bi-phaser 110 comprises a vane-type phaser having a plurality of vanes 120 that pass through and seal against a plurality of arcuate cavities 122 in the drive member 112 and are secured at their opposite axial ends to front and rear closure plates 124 and 126. The design of the vane phaser is generally similar to that shown in GB 2421557, which will be described in more detail in GB 2421557.

The yoke 128 is located inside the drive member 112 behind the front plate 124 and is connected to the drive member 112 by a pin 130 which is fixed into a radial bore 132 and engages in a fulcrum pin 134 which is rotatably fitted into an axially extending bore 136 in the yoke 128. This linkage allows the yoke 128 to rotate about the pin 142 connecting it to the front camshaft bearing 118 and take up an eccentric position. The yoke 128 is positioned by two pins 140 which are fixed into the front plate 124 of the phaser and engage the undulating outer profile of the yoke 128. When two pins 140 in the front plate 124 of the phaser rotate with the vane 120, the profile on the radially outer surface of the yoke 128 causes it to rotate about the fulcrum pin 134.

The bi-phasers 110 are intended to drive an assembled camshaft (not shown in fig. 1) having an inner shaft and a concentric outer tube, each of which is fixed for rotation with a corresponding set of cam lobes. The outer tube of the camshaft is driven via the front bearing journal 118, which in turn is driven by the yoke 128 via the connecting pin 142. The inner shaft of the camshaft is driven via a threaded shaft 144 that passes through the center of the phaser 110 and is secured to the front plate 124 via a nut 146.

The front plate of the phaser is formed of two parts 124a, 124b to simplify oil distribution within the phaser, although a single part with a complex oil bore may alternatively be used. The inner part 124a contacts the end of the vane 120 and serves to seal the front of the cavity 122 in the driving member 112, while the outer part 124b serves to seal the oil distribution groove 148 formed in the inner part 124 a. The external component 124b also has a timing feature to enable the sensor to detect the position of the phaser during operation. Four blade mounts and a center drive shaft nut 146 are used to clamp the two components together.

Fig. 2a, 2b and 2c show cross-sections through the drive member 112 and yoke 128 of the phaser of fig. 1 in three different positions. In fig. 2a, the yoke 128 is in a concentric position corresponding to mid range, whereas in fig. 2b and 2c the blade 120 is fully retarded and fully advanced, respectively. It can be seen that the pin 142 in the yoke 128, which connects it to the front bearing and thus to the outer tube of the camshaft, moves around the center of the camshaft in the opposite direction to the vane 120 and also through a different angle than the vane 120.

Although the illustrated phaser 110 shows a yoke 128 that rotates the camshaft outer tube in a direction opposite its inner shaft, a change in the profile of the radially outer surface of the yoke 128 allows two camshaft components to rotate in the same direction but by different amounts is possible. The motion of the two phaser outputs may have a linear or non-linear relationship, but there can be only one yoke position for any given vane position.

The output of the vane phaser causes the contact element to slide along the wavy surface. In the case of the embodiment of fig. 1, the contact element is a pin 140 and the undulating surface is a peripheral surface of the yoke 128, but alternatively it is possible that the yoke carries an element that slides on a surrounding inwardly facing surface.

The yoke-type phaser provides a phase output proportional to the vane-type phaser, but may have different speeds, magnitudes and directions, with the ability to reverse direction within its range relative to its input.

Heretofore, yoke phasers have encountered problems in balancing the phase response in the advance and retard directions. These problems are caused by: (i) Friction between the contact element and the undulating surface, and (ii) a resistive torque of the camshaft, particularly when the yoke output is capable of reversing relative to its input.

Disclosure of Invention

According to a first aspect of the present invention there is provided a yoke-type phaser having a drive member and a driven member rotatable about a common axis and mutually coupled by a yoke movable in a plane perpendicular to the common axis to vary the relative phase of the driven member with respect to the drive member by interaction between at least two contact elements and a undulating surface, wherein (i) one of the plurality of contact elements and (ii) the undulating surface is connected for rotation with the drive member and the other is mounted on the yoke, each contact element comprising a roller in contact with a part-cylindrical recess surface in a carrier, characterised in that the carrier of at least one of the at least two contact elements is suitably sized or adjustably mounted to set the gap between the roller and the undulating surface.

Instead of the pin 140 sliding on the undulating outer surface of the yoke 128, the present invention proposes the use of a roller. However, for example, it is not sufficient to provide a roller resting in a V-shaped groove, as this would only provide line contact. This will lead to high pressures and thus high friction. Instead, the rollers in the first aspect of the invention rest in the carrier and make surface contact to allow them to rotate freely. By enabling the position of the rollers to be adjusted, the present invention allows the gap in the phaser to be set.

According to a second aspect of the present invention there is provided a bi-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 drive member by a first phaser and to the second driven member by a yoke-type phaser, the yoke-type phaser comprising a yoke movable in a plane perpendicular 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 undulating surface, one of (i) the at least two contact elements and (ii) the undulating 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 contact with a part-cylindrical recess surface in a carrier, characterised in that at least one of the at least two contact elements is suitably sized or mounted to set the undulating surface gap between the roller and the undulating surface.

In the present disclosure, different ways for enabling the position of the roller to be adjusted are described. In some embodiments, the carrier is suitably sized. In this case, interchangeable carriers of different sizes are provided, and the size of at least one carrier is selected to provide the desired clearance. In other embodiments, uniformly sized carriers are used, but they are adjustably mounted to achieve a desired gap.

The first phaser may conveniently be a vane-type phaser.

In order to make the responses of the bi-phasers substantially identical when advancing and retarding different driven members, each of the two phasers may be provided with a respective biasing spring to counteract the resistive torque of the respective driven member.

Drawings

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

fig. 1, as previously described, shows an exploded view of a known biphaser from EP2044297,

figures 2a, 2b and 2c are cross-sectional views through the biphaser of figure 1 as previously described,

figure 3 is a schematic of two separate camshafts driven by a common dual phaser,

FIGS. 4 and 5 are exploded views similar to FIG. 1 showing two embodiments of the invention, FIGS. 6 and 7 show detailed views of two other embodiments of the invention, and

fig. 8 is a sectional view through a detail of the embodiment of fig. 7.

Detailed Description

The invention will be described with reference to a bi-phaser driving two different sets of cam lobes. A bi-phaser will be described as being connected to an assembled camshaft with one output member driving the inner shaft and the other output member driving the outer tube of the assembled camshaft. However, it should be clear that all the two-phase devices can be used to drive two separate camshafts, as schematically shown in fig. 3.

In fig. 3, the vane phaser 300 has an output connected to the first camshaft 310. The vane-type phaser 300 has a second output connected to a yoke-type phaser 320, which in turn drives a gear 330 meshed with a second gear 340 driving a second camshaft 350. Thus, in the prior art bi-phaser of FIG. 1, instead of driving the bearing ring 118 connected to the outer tube of the assembled camshaft, it could be used to drive gears of a gear train leading to a separate camshaft.

Fig. 4 is an exploded view of a dual phaser of similar construction to the prior art dual phaser of fig. 1, and for simplicity of illustration and to help avoid duplication, components functioning the same in all embodiments described below have been assigned reference numerals with the same last two significant digits.

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 fixed for 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 pins passing through circumferentially elongated slots in the outer tube. Like 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 a second set of cam lobes. The dual phaser of fig. 4 differs from the phaser shown in fig. 1 in that a vane-type phaser is used to drive the outer tube of the assembled camshaft, while a yoke-type phaser drives its inner shaft.

The input member 412 of the dual phaser of fig. 4 is connected to a gear 414 driven by the engine crankshaft instead of a sprocket. The input member has four arcuate cavities 422, each receiving a respective vane 420 dividing the cavity into two separate working chambers. The oil supplied to the working chambers by spool 450 enables the vanes 420 to move tangentially from one end of the chamber to the other.

The blades 420 are connected to two end plates 424 (only one of which is visible in the figure). Two end plates 424 seal the working chamber of the arcuate cavity 422 and serve as output members for the first vane-type phaser. The output member of the vane phaser is used to drive the outer tube of the assembled camshaft to change the phase of the first set of cam lobes relative to the crankshaft.

The inner shaft of the assembled camshaft is bolted to the tubular member 444 to which the crank arm 460 is bonded. Rotation of 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.

The crank arm 460 is connected to the yoke 428 by a fulcrum pin 435 and an eccentric sleeve 434 rotatably received in the bore 436. The diametrically opposite sides of the yoke 428 are connected to the input member 412 of the bi-phaser by pivot pins 442. The pivoting of the yoke 428 about the pin 442 causes the bore 436 to pivot about the axis of the pin 442, thereby rotating the crank arm 460 to change the phase of the inner shaft of the camshaft relative to the input member 412, which is directly driven by the engine crankshaft. Eccentric sleeve 434 is required because the distance of pin 435 from the axis of rotation of the yoke changes as the yoke pivots about pin 442.

The angular position of yoke 428 relative to input member 412 is determined by the angular position of end plate 424, which serves as the output member for blade type phasing. To this end, end plate 424 includes two contact elements, generally designated 440, that contact the undulating outer surface 428a of yoke 428. In fig. 4, one of the two contact elements 440 is shown in an assembled state, while the other is shown in an exploded view. Each contact element 440 comprises a roller 447 journalled in and in surface contact with a part-cylindrical recess 451 in the carrier 441. Carrier 441 is secured to end plate 424 by screws 443 passing through washer plate 445 and elongated slots in carrier 441. Pins 453 engaged in elongated slots 455 in end plate 424 and carrier 441 ensure proper orientation of carrier 441 while allowing adjustment of the distance of rollers 447 from undulating surface 428 a.

The journal rollers 447 in fig. 4 engaging the undulating surfaces 428a provide less frictional resistance than the pins 140 of the bi-phaser of fig. 1 and, in addition, their positional adjustability on the end plate 424 ensures that the gap between the rollers 447 and the undulating surfaces 428a can be precisely set.

The dual phaser shown in fig. 5 illustrates that the contact elements and the members to which the undulating surfaces are attached are interchangeable. Thus, in fig. 5, the contact element 540 is carried by the yoke 528 and the undulating surface is an inwardly facing cam surface 570a of the disc 570 which is secured to the end plate 524 of the vane-type phaser. The structure of the vane-type phaser is not shown in fig. 5, but is the same as in fig. 4.

In this case, roller 547 journals into and makes surface contact with a partially cylindrical groove 551a of carrier 541 sliding within channel 555 in yoke 528. The gap in this embodiment is set by proper sizing of the carrier 541.

Fig. 5 also shows that the bi-phaser may include two biasing springs 582 and 584 to counteract the resistive torque of the corresponding driven member. The spring 582 acts on the crank arm 560, and thus on the output member of the yoke phaser, through the plate 586. Instead, the spring 584 acts on the plate 590 with timing features and is fixed to the output member of the vane phaser.

Fig. 6 shows how a spacer 661 may be provided between one or both of the carriers 641 and the bottom of the channel 655 to set the gap.

Fig. 5, 6 and 7 also illustrate an alternative connection between the yoke 628 and the crank arm 660, wherein instead of an eccentric sleeve, the fulcrum pin 635 is slidable on a radial projection of the crank arm 660.

Fig. 7 and 8 illustrate another embodiment of the invention in which a hydraulic lash adjuster 893 is used in place of the shim, which is otherwise identical to the embodiment of fig. 6. Hydraulic lash adjusters are of course well known and rely on oil pressure to set a minimum lash. Fig. 8 shows that oil bores may be provided in the yoke 828 for this purpose, but the lash adjuster is more suitable for embodiments in which the undulating surface is on the circumference of the yoke.

Claims

1. A yoke-type phaser having a driving member and a driven member rotatable about a common axis and mutually coupled by a yoke movable in a plane perpendicular to the common axis to change the relative phase of the driven member with respect to the driving member by interaction between at least two contact elements and a wave surface, wherein (i) one of the at least two contact elements and (ii) the wave surface is connected for rotation with the driving member and the other is mounted on the yoke, each contact element comprising a roller in contact with a part-cylindrical recess surface in a carrier, characterized in that the carrier of at least one of the at least two contact elements is suitably sized or adjustably mounted to set a gap between the roller and the wave surface.

2. A bi-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 drive member by a first phaser and to the second driven member by a yoke-type phaser comprising a yoke movable in a plane perpendicular 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 undulating surface, (i) one of the at least two contact elements and (ii) the undulating surface being defined by or mounted on the first driven member, the other being defined by or mounted on the yoke, each contact element comprising a roller in contact with a part-cylindrical recess surface in a carrier, characterised in that the carrier of at least one of the at least two contact elements is suitably sized or adjustably mounted to set the undulating gap between the roller and the undulating surface.

3. The bi-phaser of claim 2, wherein the position of the carrier of at least one of the at least two contact elements is adjustable by shims.

4. The bi-phaser of claim 2, wherein the carrier of at least one of the at least two contact elements is held in place by a screw passing through an elongated slot in the carrier.

5. The bi-phaser of claim 2, wherein the position of the carrier of at least one of the at least two contact elements is adjustable by a hydraulic lash adjuster.

6. A bi-phaser as claimed in any one of claims 2 to 5, wherein each of the two phasers is provided with a respective biasing spring to counteract the resistive torque of the respective driven member.

7. The bi-phaser of any of claims 2-6, wherein the first phaser is a vane phaser.