WO1989001097A1

WO1989001097A1 - Torque transmitting arrangement

Info

Publication number: WO1989001097A1
Application number: PCT/GB1988/000579
Authority: WO
Inventors: David Roger Arrowsmith; Alastair John Young; David Parsons
Original assignee: Automotive Products Plc
Priority date: 1987-07-25
Filing date: 1988-07-18
Publication date: 1989-02-09
Also published as: GB9000394D0; GB2229793A; GB2229793B; AU2072788A

Abstract

A torque transmitting arrangement which includes means for absorbing or compensating for torsional vibrations comprises two coaxially arranged flywheel masses (1, 2) which are mounted for limited angular rotation relative to each other. A plurality of pivotal linkages interconnect the two flywheel masses and comprise a first link (26) pivotally connected to one of the flywheel masses, a second link (28) pivotally connected to the other of the flywheel masses, and means (30) for pivotally connecting the first and second links. Means, such as friction damping means, which in use resists relative angular rotation between the two flywheel masses may additionally be provided. A friction clutch may be secured to one of the flywheel masses to provide a simple and effective means for absorbing or compensating for torsional vibrations such as can arise in a vehicle transmission assembly.

Description

TORQUE TRANSMITTING ARRANGEMENT

The present invention relates to a torque transmitting arrangement which includes means for absorbing or compensating for torsional vibrations such as can arise in a vehicle transmission assembly.

Torque transmitting arrangements are known for example from U.K. Patent Application No. 2 152 187A in which two coaxial flywheel masses are rotatable relative to each other over a limited angle with damping means acting between the two flywheel masses. However, this known construction is complex and prone to failure and, despite the complexity the damping effect occurs in two stages and is not continuously variable with rotational speed.

It is an object of the present invention to provide a torque transmitting arrangement which is simple in construction and which incorporates a damping effect that is continuously variable with rotational speed.

According to the present invention there is provided a torque transmitting arrangement comprising:

two coaxially arranged flywheel jnasses which are mounted for limited angular rotation relative to each other; and a plurality of pivotal linkages interconnecting the two flywheel masses and comprising a first link pivotally connected to one of the flywheel masses, a second link pivotally connected to the other of the flywheel masses, and means for pivotally connecting the first and second links.

The torque transmitting arrangement may include means, such as friction damping means, which in use resists relative angular rotation between the two flywheel masses.

The friction damping means may comprise an annular pad of friction material mounted on a plate which is rotatable with one of the flywheel masses and means for urging the pad of friction material towards the other of the flywheel masses. Alternatively or additionally the friction damping means may comprise at least one profiled strip of resilient material secured to one of the flywheel masses and at least one projection provided on the other of the flywheel masses for bearing against the or each profiled strip and providing friction damping in regions of extreme relative movement between the flywheel masses.

The mass of each pivotal linkage is preferably greater in the region of the pivotal connection between the links than in the remaining regions of the links. Each pivotal linkage may incorporate an added mass in that part of at least one of the first and second links adjacent to the pivotal connection between the links. Additionally or alternatively, each pivotal linkage may incorporate an added mass in the pivotal connection between the links.

The torque transmitting arrangement may include resilient means disposed between at least one of the first and second links and at least one of the flywheel masses.

At least one of the flywheel masses may be formed with a substantially circular hub portion and at least one of the links may be provided with a curved edge having a radius of curvature substantially the same as that of the hub portion so as to be engageable with the hub portion along a substantial part of the length thereof. A resilient pad may be secured to the surface of the hub portion so as to be engageable by the link.

Ducts may be provided in at least one of the flywheel masses for the passage of cooling air.

One of the flywheel masses may be provided with a face for receiving a friction disc of a friction clutch. A friction clutch may be secured to one of the flywheel masses. For a better understanding of the present invention and to show more clearly how to carry it into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a cross-sectional view of one embodiment of a torque transmitting arrangement according to the present invention taken along the line I-I in Figure 3;

Figure 2 is a partial cross-sectional view taken along the line II-II in Figure 1;

Figure 3 is a partial cross-sectional view taken along the line III-III in Figure 1;

Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 2;

Figure 5 is a cross-sectional view taken along the line V-V in Figure 2;

Figure 6 is a cross-sectional view of a second embodiment of a torque transmitting arrangement according to the present invention taken along the line VI-VI in Figure 7; Figure 7 is a partial cross-sectional view taken along the line VII-VII in Figure 6;

Figure 8 is an elevational view of friction damping means incorporated into the embodiment of Figures 6 and 7;

Figure 9 is a view similar to that shown in Figure 2 of a third embodiment of a torque transmitting arrangement according to the present invention;

Figure 10 is a cross-sectional view of a fourth embodiment of a torque transmitting arrangement according to the present invention taken along the line X-X in Figure 11;

Figure 11 is a partial cross-sectional view taken along the line XI-XI in Figure 10;

Figures 12 and 13 illustrate characteristics of the torque transmitting arrangement according to the present invention; and

Figures 14,15 and 16 illustrate particular characteristics of the torque transmitting arrangement shown in Figures 6,7 and 8.

The torque transmitting arrangement shown in Figures 1 to 5 comprises a flywheel which is divided into two flywheel masses 1 and 2. The flywheel mass 1 is fixed on a crankshaft 3 of an internal combustion engine (not shown) by way of bolts 18 and a friction clutch 4 is secured to the flywheel mass 2. Under normal drive conditions the flywheel masses 1,2 rotate in an anti-clockwise direction in the view shown in Figure 2 and in a clockwise direction in the view shown in Figure 3. Ducts 2A for the passage of cooling air are provided in the flywheel mass 2. Also provided on the flywheel mass 2 is a central protruding hub 2B. Provided between the pressure plate 5 of the friction clutch 4 and the flywheel mass 2 is a clutch friction disc 6 which is carried on an input shaft 7 of a transmission (not shown). The pressure plate 5 of the friction clutch 4 is urged against the flywheel mass 2 by a diaphragm spring 8 which is pivotally mounted on a clutch cover 11. By actuation of the friction clutch 4, the flywheel mass 2 and thus also the flywheel mass 1 can be coupled to and uncoupled from the input shaft 7 of the transmission by way of the clutch disc 6.

The flywheel mass 1 comprises a hub 12 which is fixed on crankshaft 3, a plate 13 fixed to hub 12 by screws 14 and an annular outer mass 15 fixed to plate 13 by bolts 16. A starter ring 17 is mounted on outer mass 15. The two flywheel masses 1 and 2 are mounted rotatably relative to each other by way of a bearing 19. An inner race 20 of the bearing 19 is non-rotatably mounted on the hub 12 and is secured in place by means of a spring ring 21. Outer race 22 of the bearing ^19 is non-rotatably mounted in the hub of the flywheel mass 2 by way of an intermediate member 23. Outer race 22 is secured in place by means of a retaining ring 24 and^' a spring ring 25.

Relative rotation between the two flywheel masses 1 and 2 is controlled by five pivotal linkages evenly spaced around the flywheel masses 1 and 2 and by friction damping means. Each pivotal linkage comprises a first link 26 pivotally mounted on a hub portion of the flywheel mass 2 by way of a pivot bearing 27 and a second link 28 pivotally mounted on the flywheel mass 1 by way of a pivot bearing 29, the two links 26 and 28 being pivotally connected by means of a pivot bearing 30. It will be noted from Figure 2 that the pivot 27 is positioned radially inwardly of the pivots 29 and 30 and that the pivot 30 is positioned radially inwardly of the pivot 29. We have found that this arrangement is particularly convenient and economical of space. Resilient means in the form of a coil spring 31 is mounted on the link 28 and is engageable against an abutment 32 formed on the flywheel mass 2 in order to limit excessive movement of the link 28 under either drive or over-run conditions. Link 26 is formed with a land area 33 which adds mass to that end of the link remote from the pivot bearing 27. One edge of link 26 is curved and has a radius of curvature substantially the same as the radius of the hub portion of the flywheel mass 2. This enables the link 26 to engage with the hub portion along a substantial part of the length of the link which facilitates the construction of a compact unit and can assist in reducing any noise which may be generated should the link engage the hub portion.

The friction damping means comprises an annular pad 34 of friction material which is securely mounted on a plate 35 and is urged towards plate 13 of flywheel mass 1 by a Belleville spring 36. Plate 35 and thus annular pad 34 are prevented from rotating with plate 13 by means of projections 37 provided on plate 35 which extend into bores

38 provided on each pivot bearing 27. Belleville spring 36 is supported on flywheel mass 2 by way of a retaining ring

39 which is press fitted onto the flywheel mass 2 adjacent to the retaining ring 24 and spring ring 25.

In the torque transmitting arrangement shown in Figures 6,7 and 8 the same reference numerals as those used in Figures 1 to 5 are used to denote the same or similar parts. In the embodiment shown in Figures 6,7 and 8, projections 37 provided on plate 35 engage in slots 40 formed in the flywheel mass 2. Further friction damping means comprises profiled strips 41 of resilient material such as spring steel secured to plate 13 by means of rivets 42 and bearing against the ends of pivot pins 43 provided in the flywheel mass 2. Links 26 are pivotally mounted on pivot pins 43 and the pivot pins 43 are held in place by screws 44 which engage in an annular recess formed around the periphery of the pins. In this embodiment the strips of spring steel can be used as an alternative to or in addition to the annular pad 34 of friction material. Although the annular outer mass 15 is still fixed to the plate 13 by bolts 16, additional pins 16A are used to rotationally couple the outer mass 15 to the plate 13.

Movement of the flywheel mass 2 relative to the flywheel mass 1 towards their extremes of relative movement causes the pin 43 to engage one of the inclined faces 45 of each of the profiled strips 41. The resilient material of the strips thus provides a resistance to further relative movement between the flywheel masses 1 and 2 or increases such resistance in the regions of extreme relative movement between the flywheel masses 1 and 2. We have found the profiled strips 41 can be helpful in controlling the relative movement of the flywheel masses particularly during starting and stopping of the engine. An alternative to the land area 33 being provided on link 26 is shown in Figure 9. According to the embodiment shown in Figure 9, the pivot bearing 30 is enlarged to incorporate added mass to the region between the links 26 and 28. The pivot bearing also incorporates a land area 46. Moreover the spring 31 need not be a coil spring but could take numerous other forms including a shaped strip of resilient material.

The embodiment of the torque transmitting arrangement shown in Figures 10 and 11 is similar to that shown in Figures 1 to 5 and the same reference numerals are used to denote the same or similar parts.

The embodiment of the torque transmitting arrangement shown in Figures 10 and 11 differs primarily in the arrangement of the pivot bearings 27,30. Pivot bearing 27 is no longer provided with a bore 38 and is mounted in flywheel mass 2 in a non-rotatable manner by means of a securing pin 50 which is screwed into a threaded hole formed at the interface between the pivot bearing 27 and the flywheel • mass 2. A bush 51 facilitates rotary sliding movement between pivot bearing 27 and link 26. Pivot bearing 30 is provided with a bush 52 and pivot bearing 29 is provided with a bush 53. Because the pivot bearing 27 is no longer provided with bore 38 projection 37 extends into a recess formed in a face of the flywheel mass 2.

In order to prevent the link 26 making a noise when it comes to bear against the hub 2B of the flywheel mass 2 as will be described hereinafter, which noise could be disconcerting to the driver of a vehicle or the like in which the torque transmitting arrangement is mounted, resilient pads 54 may be secured to the outer surface of the hub 2B.

Operation of the torque transmitting arrangement shown in Figures 1 to 5 will now be described with reference to Figures 12 and 13 which illustrate centrifugal stiffness characteristics of the arrangement in the absence of friction damping means and springs 31. Figure 12 illustrates centrifugal stiffness characteristics of the arrangement under drive conditions when power is being transmitted from flywheel mass 1 to flywheel mass 2 and Figure 13 illustrates centrifugal stiffness characteristics of the arrangement under over-run conditions.

Under no-load conditions with the clutch disengaged, centrifugal force acts on the pivotal linkages and particularly on the regions of added mass and urges the linkages in a radially outward direction. At higher rotational speeds the centrifugal force is greater and whilst this does not affect the configuration under no-load conditions it greatly affects the force required to move the flywheel mass 2 relative to the flywheel mass 1. If the clutch is engaged and power is transmitted from flywheel mass 1 to flywheel mass 2 there is a tendency for the two masses to rotate relative to ^'each other. At relatively low speeds when the influence of centrifugal force is small the flywheel masses more readily relative to each other. However at relatively high speeds the influence of centrifugal force is much greater and relative rotation of the flywheel masses requires greater force.

Under conditions of over-run the effects are similar except that in the embodiments described the pivotal link 26 folds under the pivoted link 28 and the curved face of the link 26 adjacent to the land area 33 eventually comes to bear against the hub 2B of the flywheel mass 2 which forms a travel stop and prevents further relative movement of the flywheel masses.

While the characteristics of the torque transmitting arrangement shown in Figures 6,7 and 8 are generally the same as those of the arrangement shown in Figures 1 to 5, the profiled strips do exert an influence and this can be seen from Figures 14,15 and 16 in which Figure 14 shows the static characteristics of the arrangement under both drive conditions when power is being transmitted from flywheel mass 1 to flywheel mass 2 and under over-run conditions when torque is transmitted from flywheel mass 2 to flywheel mass 1. Figure 15 shows the static characteristics under drive conditions in more detail, and Figure 16 shows the static characteristics under over-run conditions in more detail. Under drive conditions the effect of the profiled strips and the effect of the annular pad of friction material are combined with the buffer spring so that relative rotation of the flywheel masses requires a progressively increasing force. At large deflections under conditions of over-run the pin 43 can ride over the top of the inclined face 45 of the profiled strip 41 which would result in a rapidly increasing deflection. However, we have found that the buffer spring 31 can be brought into effect at this stage to prevent uncontrolled increases in the deflection.

The torque transmitting arrangement ^• according to the present invention allows a large angle of deflection with a progressive damping effect. In addition the damping effect is variable depending on the rotational speed of the flywheel. The variable stiffness of the pivotal linkages as a result of centrifugal force continuously alters the natural frequency of the engine/transmission assembly and ensures that resonance can be avoided while the construction of the torque transmitting arrangement remains relatively simple.

Claims

1. A torque transmitting arrangement for a vehicle characterised in that the arrangement comprises:

two co-axially arranged flywheel masses (1,2) which^" are mounted for limited angular rotation relative to each other; and

a plurality of pivotal linkages interconnecting the two flywheel masses and comprising a first link (26) pivotally connected to one of the flywheel masses, a second link (28) pivotally connected to the other of the flywheel masses, and means (30) for pivotally connecting the first and second links.

2. A torque transmitting arrangement as claimed in claim 1, characterised in that the arrangement includes means which in use resists relative angular rotation between the two flywheel masses.

3. A torque transmitting arrangement as claimed in claim 2, characterised in that friction damping means is provided to resist angular rotation.

4. A torque transmitting arrangement as claimed in claim 3, characterised in that the friction damping means comprises an annular pad (34) of friction material mounted on a plate (35) which is rotatable with one of the flywheel masses and means (36) for urging the pad of friction material towards the other of the flywheel masses.

5. A torque transmitting arrangement as claimed in claim 3 or 4, characterised in that the friction damping means comprises at least one profiled strip (41) of resilient material secured to one of the flywheel masses and at least one projection (43) provided on the other of the flywheel masses for bearing against the or each profiled strip and providing friction damping in regions of extreme relative movement between the flywheel masses.

6. A torque transmitting arrangement as claimed in any one of claims 1 to 5, characterised in that the mass of each pivotal linkage is greater in the region of pivotal connection (30) between the links (26,28) than in the remaining regions of the links.

7. A torque transmitting arrangement as claimed in claim 6, characterised in that each pivotal linkage incorporates an added mass (33) in that part of at least one of the first and second links (26,28) adjacent to the pivotal connection (30) between the links.

8. A torque transmitting arrangement as claimed in claim 6 or 7, characterised in that each pivotal linkage incorporates an added mass in the pivotal connection between the links (26,28).

9. A torque transmitting arrangement as claimed in any one of claims 1 to 8, characterised in that a resilient means (31) is disposed between at least one of the first and second links (26,28) and at least one of the flywheel masses (1,2).

10. A torque transmitting arrangement as claimed in any one of claims 1 to 9, characterised in that at least one of the flywheel masses (1,2) is formed with a substantially circular hub portion and at least one of the links (26,28) is provided with a curved edge having a radius of curvature substantially the same as that of the hub portion so as to be engageable with the hub portion along a substantial part of the length thereof.

11. A torque transmitting arrangement as claimed in claim 10, characterised in that a resilient pad (54) is secured to the surface of the hub portion so as to be engageable by the link.

12. A torque transmitting arrangement as claimed in any one of claims 1 to 11, characterised in that ducts (2A) are provided in at least one of the flywheel masses for the passage of cooling air.

13. A torque transmitting apparatus as claimed in any one of claims 1 to 12, characterised in that one of the flywheel masses is provided with a face for receiving a friction disc (6) of a friction clutch (4).

14. A torque transmitting apparatus as claimed in claim 13, characterised in that a friction clutch (4) is secured to one of the flywheel masses.