TORSIONAL VIBRATION DAMPERS

Abstract: A torsional vibration damper (16) for use in drive lines having an input member (17) for connection with an associated engine and an output member (26) for connection with an associated driveline, these members being relatively rotatable via a support bearing (30) acting therebetween against the action of a torsional damping means to damp torsional vibrations in the associated driveline. The torsional damping means is in the form of circumferentially disposed springs (18) acting to oppose relative rotation of the input and output members and a linkage means (28, 35) interconnecting the input and output members and which generates a speed dependent damping effect. The springs and linkage means are located side by side in an axial sense. The damper may be used in combination with an Electro-magnetic combined Starter, Alternator and Damping unit (10) and in particular mounted within a rotor element (11) of such a unit.

Description: TORSIONAL VIBRATION DAMPERS This invention relates to torsional vibration dampers, hereinafter referred to as of the kind specified, for use in drive lines, the dampers comprising an input member for connection with an associated engine and an output member for connection with an associated driveline, said members being relatively rotatable via a support bearing acting therebetween against the action of a torsional damping means to damp torsional vibrations in the associated driveline Such dampers may be used, for example, in the drivelines of all types of vehicles or in stationary drive applications such as, for example, generators or pumps Such torsional vibration dampers may be in the form of twin mass flywheels in which the input and output members are each of significant mass or may have relatively light input and output members which possess relatively little mass Such dampers may be positioned at any convenient point in the driveline There is an increasing interest in the use of Electro-magnetic combined Starter, Alternator and Damping units, hereinafter referred to as being "ESAD units of the kind specified", comprising an engine driven inner rotor element and an outer stator element which, under the control of an electronic controller, can function as a starter motor for an associated engine, an alternator for generating electrical power and an electrical damper for damping torsional vibrations emanating from the associated engine Such an ESAD unit can be used to provide a temporary boost to the torque provided by the engine to facilitate, for example, overtaking or hill starting in vehicular applications It is an object of the present invention to provide a torsional vibration damper of the kind specified which is particularly suitable for use with an ESAD unit of the kind specified Thus, according to a first aspect of the present invention there is provided a torsional vibration damper of the kind specified in which the torsional damping means comprises a plurality of circumferentially disposed springs acting to oppose relative rotation of the input and output members and a linkage means interconnecting the input and output members and which generates a speed dependent damping effect, the springs and linkage means being located side by side in a axial sense As will be appreciated, with such an arrangement the radial extent of the damper is significantly reduced, compared to a traditional speed sensitive torsional vibration damper of the kind specified, making the damper particularly suitable for use with ESAD units of the kind specified Also, the speed dependent damping effect can be used to accommodate the torque boost capability of such ESAD units at higher engine speeds since, for example, typically the torque capacity of the linkage means can be arranged to increase from say 200- 300 NM at idle speed to say 800 NM at 5000 r p m The input member may be formed from sheet metal with a portion which at least partially encircles the springs, one end of the linkage being attached to the spring encircling portion of the input member The springs may react between abutments on the input member (e g the encircling portion) and a generally disc-shaped member with radially extending fingers which extend between the springs so that the springs can be stressed in drive and/or overrun conditions of the damper The disc-shaped member may be connected to a first end of a first generally tubular member the other end of which is connected with the output member, the main bearing being supported between the first generally tubular member and a radially inner second generally tubular member which is connected to the input member Preferably, the main bearing is a plain bearing sleeve which may be formed in situ between the first and second generally tubular members in accordance with the Applicant's co-pending application No 9918716 3 Preferably the input member and the second generally tubular member are connected with the associated engine by the same attachment bolts These bolts may be semi-captive The first generally tubular member may be attached to the output member by pins on which parts of the linkage means pivot Additionally or alternatively the first generally tubular member may be attached to the output member by separate rivets or other fasteners positioned circumferentially in between the linkage means pivot pins Typically the linkage means will comprise a bob weight and link arrangement as disclosed in, for example, the Applicant's patent GB 2229793 Other linkage arrangements as, for example, the flexible linkage arrangement disclosed in the Applicant's co-pending applications WO99/41524 (see claim 19 of the present invention), the speed dependant mass and link arrangements of co-pending application WO 98/51940 track (see claim 15 of the present application) and the multiple link arrangements of co-pending application WO 97/30298 track (see claim 18 of the present application) may also be used Accordingly the relevant disclosures of the above referred to patent and co-pending applications are hereby incorporated in the present application. The second generally tubular member may have a radially outwardly extending flange against which an axially acting spring reacts to bias the output member axially thus biasing a radially extending portion of the bearing sleeve against the input member to control the axial position of the input and output members during relative rotation The spring may react against the output member via an annular plate and friction disc This contact between the bearing sleeve flange and the input member and between the spring means and the output member may be used, if required, to generate significant friction to oppose the relative rotation of the input and output members A torsional vibration damper as described above may be in the form of a twin mass flywheel with the input inertia mainly constituted by the rotor element of an associated ESAD unit of the kind specified In a torsional vibration damper as described above the damper may carry a pilot bearing for an input shaft of an associated drive-line transmission unit This pilot bearing may be carried in a sleeve on which the damper is centred relative to the associated engine The invention also provides an ESAD unit of the kind specified in combination with a twin mass flywheel in which the input inertia of the twin mass flywheel is mainly/significantly constituted by the rotor element of the ESAD unit The invention also provides an ESAD unit of the kind specified in combination with a twin mass flywheel in which the twin mass flywheel includes a speed sensitive torsional damping means As indicated above, the use of a twin mass flywheel who's torque capacity/damping effect varies in a speed dependent manner enables the torque boost capability of the ESAD unit to be accommodated at higher engine speeds The invention further provides an ESAD unit of the kind specified in which the rotor element of the unit is in the form of a hollow dish within which a torsional vibration damper of the kind specified is at least partially disposed For example, part of the output member of the torsional vibration damper (e g that part engaged by a transmission clutch) may be disposed outside the stator element Also, part of the input member may also extend outside the stator element, for example, engine management features such as sensor teeth etc The invention also provides an arrangement in which the rotor element of an ESAD unit of the kind specified and an associated torsional vibration damper are secured to an associated engine by the same attachment bolts Alternatively, the torsional vibration unit may be secured to the ESAD unit which is then separately secured to the engine When a torsional vibration damper and ESAD unit are used in combination a torque limiting device may be provided between the two The invention also provides an ESAD unit of the kind specified with a torsional vibration damper of the kind specified mounted within the rotor element and sealing means operative between the rotor and output member to control the egress of potentially damaging particles from the damper onto the ESAD unit The invention further provides the pre-assembled combination of an ESAD rotor element containing a torsional vibration damper of the kind specified with a drive clutch attached to the output member of the damper The present invention will now be described, by way of example only, with reference to the accompanying drawings in which - Figure 1 is a first radial half section through a torsional vibration damper in accordance with the present invention mounted within an ESAD unit of the kind specified, Figure 2 is a second radial half section through the same damper on a different radial plane, Figure 3 is a perspective view of the same damper, Figure 4 is a side view of a spring-engaging disc-shaped member used in the above damper, Figure 5 is a part sectional perspective view of the same damper with part of the input member removed, Figure 6 is a radial perspective view of the same damper, Figure 7 shows an alternative centring arrangement , and Figures 8 and 9 show alternative sealing arrangements Referring to figures 1 to 6 these show part of an ESAD unit 10 of the kind specified which has an inner rotor element 11 which is secured to an engine crankshaft flange 12 by bolts 13 and a rotor element, part of which is indicated at 14, which surrounds the rotor element and is non- rotationally supported from the associated engine Since the details of the ESAD unit do not form part of the present invention no further description of this unit will be provided in the present application Rotor element 11 is generally dish-shaped having a central recess 15 within which a torsional vibration damper 16 is mounted Damper 16 comprises an input member 17 formed from sheet metal material which has a radially extending inner portion 17a and a generally channel-shaped encircling portion 17b within which are housed six generally circumferentially extending coil springs 18 Encircling portion 17b includes pressed out portions 17c which form cut-outs 19 which house the springs 18 In the example shown (see Figures 4 and 5) springs 18 are of three different types Type 18A is relatively long and of a relatively low spring rate, type 18B is of medium length and of a medium spring rate, and type 18C is of relatively short length and relatively high spring rate There are two springs of each type with the ends of the springs contacting the ends 20 and 21 of each respective cut-out Between adjacent cut-outs 19 extend radial fingers 22 formed on a disc-shaped member 23 Disc member 23 is riveted at 24 to a first generally tubular member 25 which is secured at its other end to output member 26 by rivets 25a A second inner generally tubular member 25a is provided which has a radially inwardly extending flange portion 29 which is bolted to the crankshaft flange 12 by bolts 13 which also extend through input member 17 Between the first and second generally tubular members 25 and 25a a main bearing sleeve 30 is provided This bearing may be manufactured by machining or may be cast in situ as per the Applicant's co-pending patent application no 9918716 3 The other end of tubular sleeve member 25a is provided with a radially outwardly extending flange 31 against which a belleville spring 32 reacts Spring 32 bears on output member 26 via annular plate 33 which presses a friction disc 33a against member 26 Belleville 32 presses output member 26 towards input member 17 to generate friction between a flange 34 provided on bearing sleeve 30 and the contacting input member portion 17a and disc-shaped member 23 The frictional contact between bearing flange portion 34 and input member 17a and discshaped member 23 can be used to generate significant friction damping, if desired, to resist the relative rotation of the input member 17 and output member 26 The friction generated by belleville 32 forcing plate 33 and disc 33a against member 26 may similarly be used to provide significant friction damping if required As best seen from figure 4, with the damper rotating in direction D and in the 'drive' condition, the input member 17 tends to move relative to the damper disc-shaped member 23 in direction D so that the ends 18 A' 18B' and 18C of springs 18 A, 18B and 18C tend to move towards the edges 22a of fingers 22 Thus after a predetermined amount of relative rotation between input and output members (determined by the clearances a, b and c respectively) the springs 18 A, 18B and 18C begin to be compressed This provides a progressively increasing spring rate as the amount of relative rotation increases When the damper is operating in the 'overrun' condition the edges 18A", 18B" and 18C" of springs 18A, 18B and 18C tend to move towards the edges of 22b of fingers 22 so that a progressive increase in spring rate is also provided in overrun The clearances a, b and c may be the same in the drive and overrun condition or may be different depending on the operating characteristics required In the arrangement shown in Figure 4 all the springs are compressed in the 'drive' and 'overrun' conditions This need not be the case and, for example, by varying the arrangement of fingers 22 (e g by eliminating alternate fingers 22) the springs compressed during 'drive' may not be the same springs compressed on 'overrun' As a further alternative variable rate springs can be used Input member 17 is also connected with output member 26 by a plurality of linkages, best seen in figure 3, which comprise six bob weights 28 pivoted on pins 27 and six connecting thin links 35 which are pivoted via pins 36 to the bob weights and via pins 37 to the encircling portion 17b of the input member Such bob weight type linkages are described in, for example, the Applicant's co-pending patent application no WO 99/41524 These linkages produce a damping effect which has a stiffness which increases with the speed of rotation of the damper As can be seen from figure 2, since the bob weights 28 are of relatively thick axial thickness 't', they are each supported on pins 27 via a pair of spaced bearing bushes 28a Similarly pins 36 which rotate with links 35 are supported in bob weights 28 via bearing bushes 36a and pins 37 carry floating bushes 35a which rotate with links 35 The output member 26 is partially disposed outside the ESAD unit and has a friction surface 36 against which a vehicle drive clutch is engaged The clutch which may be of the standard single plate type has a housing 37 which is secured to output flywheel member 26 by bolts or rivets extending through holes 38 to transmit drive from output flywheel 26 to an associated vehicle transmission As will be appreciated the relative rotation of the input member 17 and the output member 26 is resisted by a combination of compression of springs 16 and the stiffness generated by bob weight linkages 28 together with the friction, descπbed above, generated by belleville spring 32 etc The rotor element 11 which is rotationally fixed relative to input member 17 forms, in effect, the main part of the input mass of a twin mass flywheel A pilot sleeve 40 is supported in the central bore 41 of damper 10 to centre the damper relative to crankshaft bore 12a and also to support, via bore 42, an input shaft (not shown) into an associated drive line transmission positioned to the right of the damper as shown in figure 1 A rod or other means could be inserted down central bore in sleeve 40 to assist in the mounting of rotor 11 and damper 16 etc on to crankshaft 12 Figure 7 shows an alternative centring arrangement in which input member 17 and generally tubular member 25a are centred via surface 1 la on rotor 1 1 and rotor 11 is in turn centred at surface 12b on crankshaft 12 In Figure 7 pins 27 are extended to also replace rivets 24 and secure disc member 23 to first generally tubular member 25 Rotor 11 also carries a sealing means in the form of sheet metal ring 50 for sealing the damper 16 against the egress of any potentially damaging particles emanating from the damper which might damage the surrounding ESAD unit Ring 50 has an inner flange 51 which is a press-fit into the rotor 11 and radially extending portion 52 and axially extending portion 53 which closely surrounds the adjacent profile of the output member 26 to control the escape of particles from the damper 16 via the clearance between relatively rotating components 11 and 26 Ring 20 could also be arranged to carry engine management features such as sensor teeth or could be extended or augmented to include extra inertia if desired Alternatively, more conventional sealing arrangements, as shown in Figures 8 and 9 may be employed between the components 11 and 26 which use rubber or other seals indicated at 60 and 70 respectively Such seals will need to be capable of operating at temperatures of the order of 200° C Various alternatives to the construction described above are possible For example, instead of securing the torsional vibration damper 16 and rotor element 11 to the crankshaft flange 12 using the same bolts 13, the damper 16 could be secured to the rotor element 10 which is then separately secured to the crankshaft flange 12 Also, if design conditions dictate it to be necessary, a torque limiting device such as a slipping clutch may be positioned in the drive connection between the ESAD unit and the torsional vibration damper Further, belleville spring 32 and associated plate 33 and disc 33a may be replaced by an axial thrust bearing which loads the bearing flange 34 against the input member 17

Claims: CLAIMS 1) A torsional vibration damper of the kind specified in which the torsional damping means comprises a plurality of circumferentially disposed springs acting to oppose relative rotation of the input and output members and a linkage means interconnecting the input and output members and which generates a speed dependent damping effect, the springs and linkage means being located side by side in a axial sense 2) A damper according to claim 1 in which the input member is formed from sheet metal with a portion which at least partially encircles the springs, one end of the linkage being attached to the spring encircling portion of the input member 3) A damper according to claim 1 or 2 in which the springs react between abutments on the input member and a generally disc-shaped member with radially extending fingers which extend between the springs so that the springs can be stressed in drive and/or overrun conditions of the damper 4) A damper according to claim 3 in which the disc-shaped member is connected to a first end of a first generally tubular member the other end of which is connected with the output member, the main bearing being supported between the first generally tubular member and a radially inner second generally tubular member which is connected to the input member 5) A damper according to any one of claims 1 to 4 in which the main bearing is a plain bearing sleeve which may be formed in situ between the first and second generally tubular members 6) A damper according to claim 4 or 5 in which the input member and the second generally tubular member are connected with the associated engine by the same attachment bolts 7) A damper according to claim 6 in which the attachment bolts are semi-captive 8) A damper according to any one of claims 4 to 7 in which the first generally tubular member is attached to the output member by pins on which parts of the linkage means pivot 9) A damper according to any one of claims 4 to 7 in which the first generally tubular member is attached to the output member by separate rivets or other fasteners positioned circumferentially in between the linkage means pivot pins 10) A damper according to any one of claims 4 to 9 in which the second generally tubular member has a radially outwardly extending flange against which an axially acting spring reacts to bias the output member axially thus biasing a radially extending portion of the bearing sleeve against the input member to control the axial position of the input and output members during relative rotation 11) A damper according to claim 10 in which the spring reacts against the output member via an annular plate and friction disc 12) A damper according to claim 10 or 11 in which the contact between the bearing sleeve flange and the input member and between the spring means and the output member is arranged to generate significant friction to oppose the relative rotation of the input and output members 13) A damper according to any one of claims 1 to 12 which carries a pilot bearing for an input shaft of an associated drive-line transmission unit 14) A damper according to claim 13 in which the pilot bearing is carried in a sleeve on which the damper is centred relative to the associated engine 15) A damper according to any one of claims 1 to 14 in which the centre of gravity of the linkage means moves radially with respect to the axis as the input and output members rotate relative to each other and the centripetal loads acting on the linkage means as the damper rotates tend to bias the input and output members towards a predetermined relative rotational zone 16) A damper according to claim 15 in which the linkage means comprises a plurality of linkage arrangements each comprising two or more interconnected links 17) A damper according to claim 16 in which one of the links of each linkage functions like a bob-weight 18) A damper according to claim 16 in which each linkage arrangement comprises two or more circumferentially spaced main links pivotally mounted on one of the input or output members with the or each circumferentially adjacent pair of main links interconnected via a generally circumferentially extending connecting linkage, and an anchor link which connects the multi-link linkage with the other of the input or output members, relative rotation of the input and output members causing the multi-link linkage to be pivotted relative to said one of the input or output members by the anchor link, so that when the damper is rotating, relative rotation of the input and output members is resisted by centripetal forces acting on the linkage arrangement 19) A damper according to any one of claims 16 to 18 in which at least one of the links of each linkage arrangement is flexible in an axial sense relative to the axis of relative rotation of the input and output members 20) A damper according to any one of claims 1 to 19 in which the input and output members are of significant mass and the unit operates as a twin mass flywheel 21) A damper according to claim 20 in combination with an ESAD unit of the kind specified in which the input member is mainly constituted by the rotor element of the ESAD unit 22) An ESAD unit of the kind specified in combination with a twin mass flywheel which includes a speed sensitive torsional damping means 23) A combination according to claim 22 in which the twin mass flywheel is in accordance with claim 20 24) A combination according to claim 22 or 23 in which the rotor element of the ESAD unit is in the form of a hollow dish within which the remainder of the twin mass flywheel is at least partially disposed 25) A combination according to any one of claims 22 to 24 in which a torque limiting device is provided between the ESAD unit and the twin mass flywheel 26) An ESAD unit of the kind specified with a torsional vibration damper of the kind specified mounted within the rotor element and sealing means operative between the rotor and output member to control the egress of potentially damaging particles from the damper onto the ESAD unit 27) A pre-assembled combination of a rotor element of an ESAD unit of the kind specified containing a torsional vibration damper of the kind specified with a drive clutch attached to the output member of the damper 28) A torsional vibration damper of the kind specified constructed and arranged substantially as hereinbefore described with reference to and a shown in any one of the accompanying drawings

Inventors: COOKE RICHARD DAVID MAITLAND, LAMBERT ADAM JOHNSON, COOKE, RICHARD, DAVID, MAITLAND, LAMBERT, ADAM, JOHNSON
Applicants: AP TMF LTD, COOKE RICHARD DAVID MAITLAND, LAMBERT ADAM JOHNSON, AP TMF LIMITED, COOKE, RICHARD, DAVID, MAITLAND, LAMBERT, ADAM, JOHNSON
Application year: 2000
Main classification: F16F15
IPC codes: F16F15