GB2191265A

GB2191265A - Fluid damped flywheel

Info

Publication number: GB2191265A
Application number: GB08712922A
Authority: GB
Inventors: David Parsons
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1986-06-03
Filing date: 1987-06-02
Publication date: 1987-12-09
Anticipated expiration: 2007-06-02
Also published as: GB8613383D0; GB2191265B; GB8712922D0

Abstract

A fluid damped flywheel includes first and second members (10 and 16) each adapted to be connected to respective rotary components (50, 15), means (25) being provided to resiliently interconnect the first and second members (10 and 16), so as to permit limited relative rotation therebetween. The first and second members (10 and 16) define therebetween an annular damping chamber (32), said chamber (32) being divided into compartments by a series of radially extending vanes (33 and 34) spaced circumferentially around the damping chamber (32), adjacent vanes (33 and 34) being mounted on a different one of said first and second members (10 and 16) so that upon relative movement of said members (10 and 16), adjacent vanes (33 and 34) will move relative to one another, this motion being damped by fluid in the chamber (32). <IMAGE>

Description

SPECIFICATION Fluid damped flywheel The present invention relates to fluid damped flywheels.

According to one aspect of the present invention a fluid damped flywheel comprises a first member adapted to be drivingly connected to a first rotary component and a second member adapted to be drivingly connected to a second rotary component, said first and second members being drivingly interconnected by means which will permit limited rotation of one member relative to the other while imposing a restoring force therebetween, said first and second members having co-operating formations which define an annular damping chamber, said annular damping chamber being divided into compartments by a series of radially extending vanes spaced circumferentially around the damping chamber, adjacent vanes being mounted on a different one of said first and second members so that upon relative movent of said members, adjacent vanes will move relative to one another.

The damping chamber is filled with a fluid, so that movement of the vanes mounted on one member relative to those mounted on the other member will be opposed by the fluid, thereby damping relative movement the two members. The degree of the damping will depend on the density and viscosity of the damping fluid and the size of the gaps between the vanes and the formations defining the damping chamber.

Preferabiy, one of the members of the flywheel defines a fluid tight chamber which is filled with a hydraulic damping fluid which in addition to being used to damp relative rotation of the members of the flywheel also increase its moment of inertia. However, according to an alternative embodiment, air may be used as the damping fluid, so that there will be no need for a fluid tight chamber to contain the damping fluid.

Various embodiments of the invention are now described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a sectional partial plan view of a flywheel formed in accordance with the present invention; Figure 2 is a section through the flywheel shown in Fig. 1; Figure 3 is a section similar to that shown in Fig. 2 of an alternative flywheel formed in accordance with the present invention; Figure 4 is a section, at a different angular position, showing a detail of the flywheel shown in Fig. 3; Figure 5 is a sectional partial plan view of a further flywheel formed in accordance with the present invention; Figure 6 is a section along the line VI-VI of Fig. 5; and Figure 7 is a section along the line VII-VII of Fig. 5, on an enlarged scale.

The flywheel illustrated in Figs. 1 and 2 comprise a cover 10 formed from two dished pressings 11 and 12 which are welded together around their outer periphery. One of the pressings 12 is provided with a central flanged aperture 13 which may be sealed to a journal 14 on a drive shaft 15, so that the cover 10 will define a fluid tight chamber which may be filled with hydraulic fluid. The cover 10 is provided with a series of circumferentially spaced bolts 51 by means of which it may be secured to a rotary component, for example the crank shaft of an engine, via a mounting plate 50.

An inner hub 16 has internal splines 17 by means of which it may be mounted on a correspondingly splined portion of shaft 15, so that it is constrained to rotate therewith. A pair of side plates 18 are secured to an outwardly extending radial flange 19 on the inner hub 16 by means of a plurality of circumferentially spaced rivets 20.

A pair of diametrically opposed outer hub plates 21 are secured to the cover 10 by means of rivets 22, so that the hub plates 21 extend inwardly towards the flange 19 of the inner hub 16 and between the side plates 18 secured thereto. Each hub plate 22 has an opening or window 23 and corresponding diametrically opposed windows 24 are provided in the side plates 18. Coil springs 25 are located in each set of windows 23 and 24 and are retained therein by spring retaining formations 26 formed by deforming the periphery of the windows 25 in the side plates 18.The coil springs 25 bear against the ends of the windows 23 in the hub plates 21 and the ends of the windows 24 in side plates 18 to allow relative angular deflection between the inner hub 16 and the cover 10 which will absorb torsional shocks between the rotary components, the inner hub 16 and cover 10 being restored to their initial relative positions by the restoring force exerted by springs 25.

A second pair of coil springs 27 are located at 90" to the coil springs 25 in further windows 28 in the side plates 18. These springs 27 are abutted by formations 29 on the outer hub plates 21, after the outer hub plates 21 have deflected to a certain extent relative to the inner hub 16, thereby providing a delayed reinforcement to the shock absorbing characteristics.

With the arrangement described so far, the coil springs 25 and 27 will absorb shocks due to variations in torsional load, but once steady state conditions are acheived, the restoring force of the coil springs 25 and 27 will tend to set up torsional vibrations in the drive train.

In order to avoid this, an annular formation 30 of generally "L" section is secured to the cover member 10 by means of rivets 22. This formation 30 co-operates with a second annu lar formation 31 of channel section which is rivetted to one of the side plates 18, to define an annular damping chamber 32. A series of vanes 33 are provided, in circumferentially spaced relationship, on formation 30 and these vanes 33 alternative with similar vanes 34 provided on the formation 31 to divide the annular damping chamber 32 into a series of compartments. As the cover member 10 is deflected relative to the inner hub 16, the vanes 33 and 34 will move relative to one another.In order to permit such movement of the vanes 33 and 34, fluid within the damping chamber 32 must be forced past the vanes 33 and 34, which will resist movement thereof and thus dampen torsional vibrations between the cover 10 and inner hub 16.

In the embodiment illustrated in Figs. 3 and 4, additional friction damping means is provided between the side plates 18 and the inner edge of the outer hub plates 21. The friction damping means comprises friction washer 60 which is keyed to the side plate 18 by means of tab 61. A Belleville spring washer 62 urges the washer 60 into frictional engagement with the inner edge of the hub plates 21, to dampen deflection between the cover 10 and the inner hub 16.

The annular chamber 65 in this embodiment is defined by a single annular formation 66 which is rivetted to one of the side plates 18 as illustrated in figure 4. This formation 66 co-operates with a portion of the pressing 12 to define an annular chamber 65. One set of vanes 67 are secured to the formation 66 while the other set of vanes 68 are welded to the pressing 12.

In the further embodiment illustrated in Figs.

5 to 7, the cover 10 is formed from two machined parts 111 and 112. These parts 111 and 112 are bolted together with an annular plate 130 therebetween to define an inwardly opening annular channel 114. The open channel 114 is closed by annular member 131, to define an annular damping chamber 132. The amular member 131 is supported on inner hub 16 for rotation therewith by means of a spoked web 140.

The annular chamber 132 is divided into compartments by means of four blocks 133 which are bolted to machined part 112 in the part thereof defining the annular channel 114, the blocks 133 being positioned at 90" intervals around the annular channel 114. Four vanes 134 are provided on the annular mem ber 131, again spaced at 90" intervals and arranged such that when the hub 16 and cover 10 are in their normal relative positions, the vanes 134 will be positioned intermediate of the blocks133. The blocks 133 and vanes 134 fit closely within the channel 114 so as to provide relatively fluid tight compartments therebetween while permitting relative move ment of annular member 131 relative to the cover 10. Restricted orifices 145 are provided through the blocks 133 so as to connect the compartments on either side of each block.

Each vane 134 on member 131 has a radial bore 150 which opens to the internal diameter of member 131. Transverse bores 151 and 152 are provided, one from each of the compartments on each side of the vane 134 into bore 150. As illustrated in detail in Fig. 7, each of the bores 151 and 152 has a nonreturn ball valve 153 which permits fluid to enter the respective compartment from the internal diameter of member 131, but prevents fluid leaving the compartment.

As with the previous embodiments the cover 10 together with damping chamber 132 is filled with fluid. Upon relative movement of cover 10 relative to hub 16, say anticlockwise as viewed in Fig. 5, the compartment to the right of vane 134 will be reduced in size thus compressing the fluid therein and forcing it through the restricted orifice 145 to damp the movement. At the same time, the compartment to the left of vane 134 will increase in size thus reducing the pressure therein. While fluid will be forced into that compartment through the restricted orifice 145 in the block 133 defining the other end of this compartment, because of the restriction, cavitation will occur which would reduce the damping efficiency on return movement. This is avoided by means of the bores 150 and 151 which permit fluid to be drawn into the compartment from inside member 131. The damping arrangement will function likewise if relative motion is in the opposite direction.

Various modifications may be made without departing from the invention. For example, a single annular outer hub plate may be used in place of the two plates 21 described above.

This annular outer hub plate may be interconnected to the side plates by means of a plurality of spring elements, as described above.

These spring elements may be arranged to provide a single stage shock absorption or a multi-stage shock absorption characteristic may be provided by varying the length of some of the windows in the outer hub plate or side plates, so that they engage the spring elements at different angular deflections.

Claims

1. A fluid damped flywheel comprising a first member adapted to be drivingly connected to a first rotary component and a second member adapted to be drivingly connected to a second rotary component, said first and second members being drivingly interconnected by means which will permit limited rotation of one member relative to the other while imposing a restoring force therebetween, said first and second members hav ing co-operating formations which define an annular damping chamber, said annular ing chamber being divided inS,

by a series of radially extending vanes spaced circumferentially around the damping chamber, adjacent vanes being mounted on a different one of said first and second members so that upon relative movement of said members, adjacent vanes will move relative to one another so that the compartment on one side of each vane will contract while the compartment on the other side expands and vice versa.

2. A fluid damped flywheel according to Claim 1 in which restricted orifices are provided in the vanes associated with one of the members, so that upon relative movement of the members fluid will be forced through the restricted orifice from a contracting compartment to an expanding compartment.

3. A fluid damped flywheel according to Claim 1 or 2 in which means is provided for introducing fluid into each of the comparments from outside the damping chamber, as the compartment expands.

4. A fluid damped flywheel according to Claim 3 in which said means include a nonreturn valve which prevents fluid being expelled from the damping chamber, as the compartment contracts.

5. A fluid damped flywheel according to any one of Claims 1 to 4 in which one of the members defines a chamber which may be filled with a hydraulic fluid.

6. A fluid damped flywheel according to anyone of the preceding claims in which one of the members is in the form of a splined hub having an outwardly radially extending flange to either side of which are attached side plates, an outer hub plate being secured to the other member so that it extends inwardly between the side plates, spring elements being located in aligned windows in the side plate and outer hub plate to provide resilient drive means therebetween.

7. A fluid damped flywheel according to Claim 6 in which the windows in the outer hub plate or side plates are of differing size so that spring elements retained therein will be engaged at differing angular deflections of the outer hub plate relative to the side plate.

8. A fluid damped flywheel according to Claim 6 or 7 in which a pair of outer hub plates are secured to said other member at diametrically opposed positions, each plate being interconnected to the side plates by a spring element located in aligned windows in the hub plates and side plates, a further pair of spring elements being located in the side plates and abutted by the outer hub plates at a certain degree of deflection of the hub plates relative to the side plates.

9. A fluid damped flywheel according to any one of Claims 6 to 8 in which an annular formation is secured to one of the side walls and cooperates with a formation associated with said other member to define the annular damping chamber.

10. A fluid damped flywheel according to Claim 9 in which the formation on the said other member is provided by an annular chan nel member which is secured to said other member.

11. A fluid damped flywheel according to any one of the preceding claims in which additional friction damping means is provided between said first and second members.

12. A fluid damped flywheel according to Claim 11 when taken with any one of Claims 6 to 10 in which a friction washer is nonrotatively mounted with respect to one of the side plates and a Belleville spring washer acts between the side plate and the friction washer to urge the friction washer into frictional engagement with the outer hub plate.

13. A fluid damped flywheel substantially as described herein with reference to and as shown in Figs. 1 and 2, Figs. 3 and 4 or Figs. 5 to 7 of the accompanying drawings.