Vibration damper

Abstract: A vibration damper assembly comprises a torsional vibration damper with torsional springs, a mass body, and a resilient drive plate which serves as a bending stress damper. With a bearing on a reinforcement block connected to the crankshaft, the torsional vibration damper has an output member rotatably supported by the crankshaft. The resilient driver plate is operatively disposed in torque transmission relationship between the crankshaft and the mass body in such a manner an to coextend radially outwardly from the crankshaft with the torsional vibration damper.

Description: The present invention relates to a vibration damper assembly for an engine having a crankshaft, which vibration damper assembly is disposed between the engine crankshaft and a torque transmitting device such as a friction type clutch or a hydraulic torque converter. DE-A 34 40 927 discloses a torsional vibration damper having an input member and an output member. The output member is divided into a mass body, rotatably supported on the crankshaft by means of a hub portion of the mass body and a bearing, and a plate. The outer periphery of the plate is riveted to the mass body, and the plate is in contact with the torsional springs. In this damper a single element (the mass body) supports the bearing between the input member and the output member and behaves as a flywheel. JP-B2 57-18049, discloses a vibration damper assembly for an internal combustion engine. This known vibration damper assembly comprises a torsional vibration damper including torsional springs, and a resilient drive plate which serves as a bending stress damper. Two mass bodies serve as an input member and an output member of the torsional vibration damper. The resilient drive plate has an inner peripheral portion connected to the end of the crankshaft, and an outer peripheral portion connected to an inner peripheral portion of the input member of the torsional vibration damper. The output member of the torsional vibration damper is rotatably supported via a bearing by a main drive shaft. In that known damper assembly, the resilient drive plate is disposed radially inward of the input member of the torsional vibration damper, so that it is difficult to increase a radial dimension of the resilient drive plate to a satisfactory level in relation to the thickness thereof. Besides, since the output member of the torsional vibration damper is rotatably mounted on the main drive shaft near the axial end of the main drive shaft, a sufficient degree of strength is required on the main drive shaft. An object of the present invention is to provide a vibration damper assembly in which, without any increase in the outer diameter of the assembly, a radial dimension of a resilient drive plate may be increased to a satisfactory level in relation to a thickness thereof, thus making it easy to modify a bending vibration characteristic of the resilient drive plae until it fits a power transmission characteristic through the vibration damper assembly. DE-A 37 02 842, on which the preamble of claim 1 is based, discloses a vibration damper assembly comprising a torsional spring damper having an input member on the outside and an output member on the inside. A resilient drive plate is fixed to the crankshaft, and the outer rim of the resilient drive plate is fixed to the outer portion of the input member. The output member is also a flywheel, which is supported by a ball bearing on the crankshaft. The present invention provides a vibration damper assembly for an engine having a crankshaft, comprising: a torsional vibration damper supported by the crankshaft and including an input member having an inner peripheral portion operatively connected to the crankshaft and an outer peripheral portion, an output member including a hub portion, and torsional springs operatively disposed between the said input and output members; a mass body on the output side of the torsional vibration damper and supported by the crankshaft; a resilient drive plate supported by the crankshaft, having an inner periphery operatively connected to the crankshaft, extending away from the axis of the crankshaft as far as the outer periphery of the input member of the torsional vibration damper, and having an outer periphery operatively connected to the mass body for transmission of torque from the crankshaft to the mass body; and a bearing retainer connected to the crankshaft and supporting a bearing, the hub portion of the output member being coupled with the said bearing and the output member being rotatably supported via said bearing by the bearing retainer; characterised in that the mass body is operatively connected to the hub portion of the output member of that damper. In the drawings: Fig. 1 is a sectional view of a first embodiment of a vibration damper assembly according to the present invention as being disposed between a crankshaft of an engine and a torque transmitting device in the form of a single plate, dry disc clutch; Fig. 2 is a fragmentary section of a second embodiment of a vibration damper assembly according to the present invention; and Fig. 3 is a view similar to Fig. 2 showing a third embodiment of a vibration damper assembly according to the present invention. Referring to Fig. 1, there is shown a portion of an internal combustion engine including a crankshaft 1. A vibration damper assembly comprises a torsional vibration damper 2 including an input member 6, an output member 7, and torsional springs 8 disposed between the input and output members 6 and 7. The vibration damper assembly also comprises a hydraulic damper including a liquid-filled chamber 5 defined between the input and output member 6 and 7 in fluid tight manner by means of seals 9 and 10. The torsional vibration damper 2 is arranged around a bearing retainer sleeve 3 which is fixedly secured to a rear end of the crankshaft 1 by means of a plurality of bolts 4. The input member 6 includes a pair of drive plates 14 and 15 with annular sub-plates 11 and 12. The sub-plate 11 is attached to an inner side of the drive plate 14 by means of a plurality of rivets, only one being shown at 13, while the other sub-plate 12 is attached to an inner side of the other drive plate 15 by means of a plurality of rivets, only one being shown at 13. The annular sub-plates 11 and 12 are opposed and are spaced to allow a radially extending disc portion 20 of the output member 7 to extend between them. The drive plates 14 and 15 are welded together at their outer peripheries and carry a plurality of stop pins, only one being shown at 16. The sub-plates 11 and 12 are formed with a plurality of sets of circumferentially arranged windows, only one set being shown at 17. Each set of the windows 17 receive therein two of the torsional springs 8 in series with an arm 19 of one of a plurality of floating members 18. Each of the floating members 18 is movable relative to the input and output members 6 and 7 and functions to compress the associated torsional springs 8. The disc portion 20 of the output member 7 extends from an annular hub portion 22 and is formed with a plurality of stopper grooves 21 which receive the stopper pins 16, respectively. Clearances are formed between the disc portion 20 and the sub-plates 11 and 12 and these clearances are filled with liquid so that relative rotational movement of the output member 7 and the input member 6 is resisted owing to viscosity of the liquid. The drive plate 14 of the input member 6 has an inner peripheral portion interposed between the rear end of the crankshaft 1 and the bearing retainer 3 and fixedly secured to the crankshaft by means of the bolts 4. The hub portion 22 of the output member 7 is rotatably supported by a bearing 23 on the bearing retainer 3. Operatively disposed between a front axial end of the hub portion 22 and the opposed inner side of the drive plate 14 are a washer 33, a plate 34 and a disc spring 35. Fixedly secured to a rear axial end of the hub portion 22 is a resilient drive plate 24. The resilient drive plate 24 has an inner peripheral portion secured to the hub portion 22 by means of a plurality of bolts 26 and coxtends radially outwardly with the torsional vibration damper 2. Disposed between the inner peripheral portion of the resilient drive plate 24 and the bolts 26 is a reinforcement annular plate 25. The resilient drive plate has an outer peripheral portion fixedly secured to an annular mass body or disc 27 to support the latter. The previously described torsional damper 2, resilient drive plate 24 and annular mass body 27 cooperate with each other to form a flywheel 28. A clutch cover 29 has an outer peripheral portion attached to the annular mass body 27. Within the clutch cover 29 is disposed a clutch disc 30 with clutch facings 31. The clutch disc 30 is splined to a main drive shaft 32. In operation, with the clutch disc 30 in firm engagement with the mass body 27, there occurs a relative rotational displacement between the input member 6 fixedly connected to the crankshaft 1 and the output member 7 fixedly supporting the mass body 27 upon transmission of torque from the crankshaft 1 to the main drive shaft 32. This relative displacement is resisted by the torsional vibration damper 2 mechanically by torsional springs 8 and hydraulically by the liquid within the chamber 5. Thus, the torque is smoothly transmitted to the main drive shaft 32. Torsional vibration induced by the crankshaft 1 is effective reduced by the torsional vibration damper 2. From the preceding description of the first embodiment, it will be appreciated that since the resilient drive plate 24 extends outwardly from the axis of the crankshaft 1 to a radius equal to the external radius of the torsional vibration damper 2, the outer diameter of the resilient drive plate 24 is not limited by the presence of the vibration damper 2, resulting in an increased freedom in designing the outer diameter of the resilient drive plate in relation to the thickness thereof. Thus, it is easy to adjust a bending stress vibration characteristic of the resilient drive plate 24 to suit the power transmission conditions. Therefore, the natural frequency of the crankshaft system owing to bending stress can be shifted out of the normally used frequency range, resulting in considerable reduction in bending vibration of the crankshaft system. Thus, a so-called cabin confined noise is considerably reduced. Since the mass body is not supported by the main drive shaft, the amount of load on the main drive shaft is considerably reduced. Referring to Fig. 2, the second embodiment is described. This embodiment is different from the first embodiment in that an annular mass body 27 has an inner peripheral portion fixedly attached to a rear axial end of a hub portion 22 of an output member 7 of a torsional vibration damper 2, a drive plate 14 of an input member 6 of the torsional vibration damper 2 is not connected to a crankshaft 1, and a resilient drive plate 24 has an inner peripheral portion fixedly interposed between a rear end of the crankshaft 1 and a bearing carrier 3 by bolts 3 to be fixedly connected to the crankshaft 1. The resilient drive plate 24 extends radially outwardly from the crankshaft 1 to the outer periphery of the torsional vibration damper 2 and has an outer peripheral portion fixedly riveted to the input member 6 of the torsional vibration damper 2 at an outer peripheral portion thereof. Referring to Fig. 3, the third embodiment is substantially identical with the second embodiment shown in Fig. 2 except that elastomers 36 are provided between an inner race of a bearing 23 and a bearing retainer 3. These elastomers 36 function to isolate or at least reduce transmission of vibrational force from the bearing retainer 3 fixed to a crankshaft 1 to a hub portion 22 to which a mass body 27 is fixedly secured.

Claims: A vibration damper assembly for an engine having a crankshaft (1), comprising: a torsional vibration damper (2) supported by the crankshaft and including an input member (6) having an inner peripheral portion operatively connected to the crankshaft and an outer peripheral portion, an output member (7) including a hub portion (22), and torsional springs (8) operatively disposed between the said input and output members; a mass body (27) on the output side of the torsional vibration damper (2) and supported by the crankshaft (1); a resilient drive plate (24) supported by the crankshaft (1), having an inner periphery operatively connected to the crankshaft, extending away from the axis of the crankshaft (1) as far as the outer periphery of the input member (6) of the torsional vibration damper (2), and having an outer periphery operatively connected to the mass body (27) for transmission of torque from the crankshaft to the mass body; and a bearing retainer (3) connected to the crankshaft (1) and supporting a bearing (23), the hub portion of the output member (7) being coupled with the said bearing (23) and the output member (7) being rotatably supported via said bearing (23) by the bearing retainer (3); characterised in that the mass body (27) is operatively connected to the hub portion (22) of the output member (7) of that damper (2). A vibration damper assembly as claimed in claim 1, wherein the inner peripheral portion of the input member (6) of the torsional vibration damper (2) is connected to the crankshaft (1), the said inner peripheral portion of the resilient drive plate (24) is connected to the output member (7) of the torsional vibration damper, and the outer peripheral portion of the resilient drive plate (24) is connected to the mass body (27). A vibration damper assembly as claimed in claim 1, wherein the inner peripheral portion of the resilient drive plate (24) is connected to the crankshaft (1), the outer peripheral portion thereof is connected to the input member (6) of the torsional vibration damper (2), and the output member (7) of the torsional vibration damper is connected to the mass body (27). A vibration damper assembly as claimed in any one of claims 1 to 3, wherein the mass body (27) is connected to the hub portion (22). A vibration damper assembly as claimed in any one of claims 1 to 4, wherein the bearing retainer (3) has elastomeric means (36) for reducing transmission of force from the bearing retainer to the output member (7) of the torsional vibration damper (2).

Inventors: ARA HIROFUMI, HIDAKA SHIZUAKI, ISHIDAKA TSUTOMU, KOHNO SATOSHI, MORISHITA TATSUYA, YAMAGUCHI KOJI, ARA, HIROFUMI, HIDAKA, SHIZUAKI, ISHIDAKA, TSUTOMU, KOHNO, SATOSHI, MORISHITA, TATSUYA, YAMAGUCHI, KOJI
Applicants: ATSUGI UNISIA CORP, UNISIA JECS CORPORATION
Application year: 1991
Main classification: F16F15
IPC codes: F16F15