GB2241768A

GB2241768A - Driving torque vibration dumping

Info

Publication number: GB2241768A
Application number: GB9103853A
Authority: GB
Inventors: Satoshi Kohno; Tatsuya Morishita; Shoichi Tsuchiya
Original assignee: Atsugi Unisia Corp
Current assignee: Hitachi Unisia Automotive Ltd
Priority date: 1990-02-28
Filing date: 1991-02-25
Publication date: 1991-09-11
Anticipated expiration: 2011-02-25
Also published as: GB2241768B; JPH04211746A; GB9103853D0

Abstract

A fluid damper 1, in the form of a hydrodynamic damper (Fig. 1) or a viscous coupling (Fig. 3), is interposed between a crankshaft 2 and the cover of a torque converter 2. <IMAGE>

Description

DEVICE FOR TRANSMITTING AUTOMOTIVE ENGINE DRIVING TORQUE FOR AUTOMATIC POWER TRANSMISSION WITH FEATURE OF ABSORPTION OF TORSIONAL VIBRATION The present invention relates to a torque transmission device for an automatic power transmission for an automotive vehicle. More specifically, the invention relates to a torque transmission device which is capable of absorption of torsional vibration induced by an engine output fluctuation.

In recent years, there ha5 been developed and proposed a torque transmission system, between an automotive internal combustion engine and a torque converter of an automatic power transmission, which can absorbs shock induced by an engine output fluctuation. Such torque transmission device employs a torsion damper interposed between a crankshaft as the output element of the internal combustion engine and a converter cover which serves as an input element of the torque converter. One example of such type of the torque transmission device has been disclosed in the Japanese Utility Model First (unexamined) Publication 58-79156.

Such prior proposed torque transmission devices are not at all satisfactory in damping torsional vibration induced on the crankshaft. Especially, the torsional vibration on the crankshaft influences vehicular body vibration and vehicular cabin noise when the automatic power transmission operates in lock-up mode. in which the crankshaft is directly and mechanically coupled with an input shaft of the power transmission. Transmission of torsional vibration from the crankshaft to the power transmission may cause uncomfortable vehicular body vibration and noise to degrade vehicular riding comfort.

Therefore, it would be desirable to be able to provide a torque transmission device which could suppress torsional vibration transmitted from a crankshaft to a converter cover.

According to the present invention it is possible to employ a viscous coupling interposed between a crankshaft and a converter cover of a torque converter. The viscous coupling is effective for damping torsional vibration input from the camshaft by viscosity thereof.

The present invention provides a torque transmission device for an automatic power transmission, comprising: an engine output shaft, driven by engine output torque; an input element for a torque converter of the automatic power transmission, which is rotatingly driven by the engine output torque transmitted thereto; and a fluid damper disposed between the engine output shaft and the input element for connecting therebetween, the fluid damper generating a damping force in response to relative angular displacement between the engine output shaft and the inlet element.

In the preferred embodiment, the fluid damper may comprise at least one hydrodynamic damper including a movement (a movable part) connected to one of the engine output shaft and the input element and movable according to relative angular displacement between the engine output shaft and the input element, and hydrodynamic means for generating resistance against motion of the movement. In this case, the hydrodynamic damper may comprise a cylinder or ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ housing secured onto the engine output shaft, which damper housing is filled with a working fluid, and the movement comprising a piston disposed within the interior space of the damper housing for separating the interior space into two chambers and a piston rod connected to the input element.

The input element may be a converter cover of the torque converter.

The damper housing may be filled with a gas together with a hydraulic working fluid, the gas serving for absorbing fluctuation of internal pressure in the damper housing due to temperature variation.

The torque transmission device may further comprise a mechanical spring cooperative with the fluid damper for resistance against relative angular displacement between the engine output shaft and the input element.

In the alternative embodiment, the fluid damper comprises a viscous damper viscously generating resistance against relative displacement between the engine output shaft and the input element. In such case, the viscous damper may comprise a first rotary member rigidly connected one of the engine output shaft and the input element and defining circumferentially extending viscous fluid chamber filled with a viscous fluid, and a second rotary member rigidly connected to the other of the engine output shaft and the input element and having a section disposed within the viscous fluid chamber for relative angular displacement with respect to the viscous fluid chamber, the viscous viscously generating resistance against relative angular displacement between the input element.Preferably, the section of the second rotary member carries a plurality of axially extending fins and the viscous fluid chamber includes a plurality of grooves defined for receiving the fins with a substantially small clearance between mating surfaces thereof.

Similarly to the former case, the torque transmission device may further comprise a mechanical spring cooperative with the fluid damper for resistance against relative angular displacement between the engine output shaft and the input element. In this case, the first rotary element and the section of the second rotary element are cooperative to define one or more spring receptacle chambers respectively adapted to receive the mechanical spring or springs.

The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiment of the invention, which, however, should not be taken to limit the invention to the specific embodiment, but are for explanation and understanding only.

In the drawings: Fig. 1 is a section of the major part of the preferred embodiment of a torque transmission device for an automatic power transmission, according to the present invention; Fig. 2 is a section of front elevation of major part of another embodiment of the torque transmission device, according to the invention; and Fig. 3 is a section taken along line A - A of Fig. 2.

Referring now to the drawings, particularly to Fig. 1, the preferred embodiment of a torque transmission device for an automatic power transmission, is designed for transmitting engine output torque from an engine output shaft 2, i.e. crankshaft, to a torque converter 3. The torque transmission device includes a hydrodynamic vibration damper 1 disposed between the engine output shaft 2 and a converter cover 4 of the torque converter 3,for connecting therebetween. The hydrodynamic vibration damper 1 has a hollow cylinder 5. The hollow cylinder 5 is filled with a viscous working fluid with a gas. The gas is contained in the hollow cylinder for absorbing pressure variation in the hollow cylinder depending upon temperature. A piston 6 is disposed within the interior space of the hollow cylinder 5 to define mutually separated two fluid chambers.The piston 6 is formed with axial orifices 15 for permitting limited flow rate of fluid flow between the mutually separated chambers in the hollow cylinder. Flow restriction magnitude at the axial orifices 15 may be determined according to desired vibration damping characteristics of the hydrodynamic vibration damper 1. A piston rod 7 is connected to the piston 6 for thrusting movement therewith. The piston rod 7 extends through the hollow cylinder 5. A coil spring 8 is disposed in the hollow cylinder 5. The spring 8 is seated on the piston 6 at one end and onto a spring seat 9 provided in the vicinity of the axial end of the hollow cylinder, through which the piston rod extends, at the other end, for biasing the piston 6 together with the piston rod 7. A seal member 10 is provided between the axial end of the hollow cylinder and the spring seat 9 for establishing fluid tight seal while permitting thrusting motion of the piston rod 7.

The piston rod 7 of the hydrodynamic vibration damper 1 has a ring section 11 at the outer end. The ring section 11 is connected to the converter cover 4 by means of a fastening bolt 12. On the other hand, the hollow cylinder 5 of the hydrodynamic vibration damper 1 is mounted on the axial end of the engine output shaft 2 via a stay 13 which is rigidly secured on the axial end of the engine output shaft by means of a fastening bolt 14.

The converter cover 4 has a support shaft 16 which is rotatably engaged with the axial end of the engine output shaft 2. On the other hand, the converter cover 4 houses within its interior space a lock-up clutch mechanism 17, a hydrodynamic torque converter unit 18 and so forth. As is well known, the lock-up clutch mechanism 17 is connected to a turbine hub 20 in axially movable fashion. An apply chamber P1 and a release chamber P2 are defined at both sides of the lock-up clutch mechanism 17 so as to selectively establish and release lock-up state.

Introduction and draining of line pressure to the apply chamber P1 and the release chamber P2 is controlled in per se known process depending upon vehicle driving condition. Namely, when a predetermined lock-up condition is satisfied, such as that a vehicle speed becomes higher than a predetermined lock-up criterion, the line pressure is introduced into the apply chamber to engage the lock-up clutch. By engagement of the lock-up clutch, the engine output shaft 2 is directly or mechanically connected to an input shaft 19 of a power transmission unit (not shown). On the other hand, when the predetermined lock-up condition is not satisfied, the line pressure is introduced into the release chamber to maintain the lock-up clutch at disengaged state.In such case, the torque converter performs converter mode operation to hydrodynamically transmit the input torque from the engine output shaft 2 to the input shaft 19 of the power transmission unit In addition, a drive plate 21 which carries a ring gear 22 is provided. The drive plate 21 is connected to the engine output shaft 2 via hydrodynamic vibration damper 1.

On the other hand, the ring gear 22 is meshed with a gear of a starter motor (not shown) for cranking operation.

At initiation of engine cranking action, the engine output shaft 2 is driven to rotate with a drive torque input from the starter motor via the ring gear 22 and the drive plate 21. By input of the driving torque of the starter motor to the engine output shaft 2 while the torque converter 3 stays in inoperative state, relative angular displacement is caused between the engine output shaft 2 and the converter cover 4 of the torque converter 3. The piston 6 of the hydrodynamic vibration damper 1 is then driven outwardly together with the piston rod 7 against the spring force of the coil spring8. By movement of the piston, the working fluid in one of the fluid chamber is compressed to generate pressure difference between two fluid chambers. As a result, fluid flow is created through the axial orifices 15.Since the fluid flow rate is restricted by the orifices 15, hydrodynamic damping force which is active together with the spring force of the coil spring 8 is induced for resistance against relative displacement between the engine output shaft 2 and the converter cover 4. Therefore, impact at initiation of engine cranking action can be successfully absorbed for smoothly transmitting the driving torque to the converter cover 4.

The hydrodynamic vibration damper 1 is also active for absorbing the torsional vibration induced due to fluctuation of the engine output torque. Namely, similarly to that at the engine cranking action, the torsional vibration on the engine output shaft 2 causes relative angular displacement between the engine output shaft and the converter cover 4. Similarly to the above, the hydrodynamic vibration damper 1 then generate a damping force as combination of the hydrodynamic force generated by flow restriction at the orifice 15 and the spring force of the coil spring 8.

Accordingly, the engine output torque can be smoothly transmitted to the converter cover 4 via the hydrodynamic vibration damper 1. Therefore, vibration to be transmitted to the vehicular body can be satisfactorily suppressed for reducing vehicular body vibration and noise.

In the shown embodiment, viscous fluid and gas fill the hydrodynamic vibration damper 1. However, while the engine is driven, centrifugal force is active on the working fluid to force the working fluid outwards. Consequently, the gas in the cylinder 5 is displaced inwards.

Therefore, gas cannot be left in the stroke range of the piston 6. As a result, the presence of the gas may not affect the vibration damping performance of the hydrodynamic vibration damper.

Though the shown embodiment employs a specific type of hydrodynamic damper, it can be replaced with a damper unit which comprises a combination of a dash-pot and a mechanical spring. Also, it is possible to employ a plurality of hydrodynamic dampers which have no installed mechanical spring. In such a case, mechanical springs are arranged in circumferentially spaced apart relationship in alternative fashion with the separately provided hydrodynamic dampers.

Figs. 2 and 3 show another embodiment of a torque transmission device according to the invention. In this embodiment, a viscous vibration damper is employed in place of the hydrodynamic vibration damper employed in the former embodiment. The viscous vibration damper includes an input member 30 which has a radial plate section 31 formed with a plurality of concentrically arranged fins 32. On the other hand, the input member 30 has a mounting flange section 33 extending radially inward. The mounting flange section 33 is rigidly secured on the axial end of the engine output shaft 2 by means of fastening bolt 34. The input member 30 is cooperated with an output member 35 which has a connecting section 36 extending . radially outward. At the connecting section 36, the output member 35 is connected to the converter cover 4 by means of a fastening bolt 37.The output member 35 comprises a pair of generally disc shaped members 38 having a plurality of concentrically arranged fins 39 on the mutually opposing surfaces. The disc shaped members 38 are assembled and secured to each other by means of a rivet 48. The disc shaped members 38 as assembled define an internal space 40 to receive therein the radial plate section 31 of the input member 30 for permitting angular displacement relative the output member . The fins 32 on the radial plate section 31 of the input member 30 is formed in conformance with the internal space 40 defined in the output member but slightly smaller or thinner than respectively associated space for defining substantially small clearance between the mating internal surface of the output members.

The radially inner end of the output member 35 is formed with axially extending flange 41 which is placed in opposition to the outer periphery of a cylindrical major section 42 of the input member 30. Bearing seal rings 43 are disposed between the flange 41 and the major section 42 for establishing fluid tight seal while permitting relative angular displacement. A viscous fluid, such as fluidized silicone. A plurality of spring receptacle slots 45 are formed in the radial plate section 31 of the input member 30. Similarly, a plurality of spring receptacle recesses 46 are defined in the internal space 40. The spring receptacle slots 45 and the spring receptacle recesses 46 are cooperated with each other for defining spring chambers to receive therein mechanical coil springs 44. The spring chambers are arranged in circumferentially spaced apart relationship to each other. The mechanical coil springs 44 exert spring forces for resisting against relative angular displacement between the input member 30 and the output member 35. Also, the viscosity of the viscous fluid filled in the interior space 40 of the output member 35 serves for providing resistance against relative angular displacement between the input and output members 30 and 35.

Therefore, similarly to the former embodiment, relative displacement between the input and output members 30 and 35, which can be caused upon initiation of engine cranking operation, can be successfully damped to assure smooth torque transmission. Also, the shown embodiment of the viscous vibration damper is similarly effective for suppressing torsional vibration due to fluctuation of the engine output torque.

Therefore, the above-described torque transmission devices fulfill all the required functions and provide the advantages described.

While the present invention has been disclosed in detail in terms of embodiments of the invention, the invention defined by the following claims can be implemented in various ways and constructions.

Claims

Claims:

1. A torque transmission device for an automatic power transmission, comprising: an engine output shaft which is to be driven by engine output torque; an input element for a torque converter of the automatic power transmission, which is driven in rotation by the engine output torque transmitted thereto; and a fluid damper disposed between the engine output shaft and the input element, for connecting the one to the other, the fluid damper generating a damping force in response to relative angular displacement between the engine output shaft and the input element.

2. A torque transmission device as claimed in claim 1, including at least one mechanical spring arranged to resist relative angular displacement between the engine output shaft and the input element.

3. A torque transmission device as claimed in claim 1 or 2, wherein the fluid damper comprises at least one hydrodynamic damper including a movable part connected to the engine output shaft or the input element and movable according to relative angular displacement between the engine output shaft and the input element, the damper including hydrodynamic means for generating resistance against motion of the movable part.

4. A torque transmission device as claimed in claim 3, wherein the hydrodynamic damper has a cylinder secured to the engine output shaft and containing a working fluid, and the movable part comprises a piston disposed within the cylinder, for separating its interior space into two chambers, and a piston rod connected to the input element.

5. A torque transmission device as claimed in claim 4, whereinthe cylinder is filled with a hydraulic working fluid together with a gas serving for absorbing fluctuation of internal pressure in the cylinder due to temperature variation.

6. A torque transmission device as claimed in any of claims 3 to 5, wherein the movable part of the hydrodynamic damper is acted on by a mechanical spring resisting motion of the movable part.

7. A torque transmission device as claimed in any of claims 3 to 5, wherein a plurality of said hydrodynamic dampers are arranged in circumferentially spaced apart relationship in alternation with mechanical springs arranged to resist relative angular displacement between the engine output shaft and the input element.

8. A torque transmission device as claimed in claim 1 or 2, wherein the fluid damper comprises a viscous damper viscously generating resistance against relative displacement between the engine output shaft and the input element.

9. A torque transmission device as claimed in claim 8, wherein the viscous damper comprises a first rotary member connected to one of the engine output shaft and the input element and defininga circumferentially extending chamber containing a viscous fluid, and a second rotary member connected to the other of the engine output shaft and the input element and having a section disposed within the viscous fluid chamber for relative angular displacement with respect to the viscous fluid chamber, the fluid viscously generating resistance against relative angular displacement between the engine output shaft and the input element.

10. A torque transmission device as claimed in claim 9, wherein the said section of the second rotary member and the viscous fluid chamber have respective axially extending fins and grooves, the grooves receiving the fins with a slight clearance.

11. A torque transmission device as claimed in claim 9 or 10, wherein the first rotary element and the said section of said second rotary element are cooperative to define at least one spring receptacle chamber which receives a mechanical spring arranged to resist relative angular displacement between the engine output shaft and the input element.

12. A torque transmission device as claimed in any preceding claim, wherein the input element is a converter cover of the torque converter.

13. A torque transmission device substantially as described with reference to, and as shown in, Figure 1 or Figures 2 and 3 of the accompanying drawings.