Hydrodynamic torque converter

Details Hydrodynamic torque converter Hydrodynamic torque converter

2001-11-29

2003-09-23

Bonck, Rodney H. (Department: 3681)

192 clutches and power-stop control

Vortex-flow drive and clutch

Including drive-lockup clutch

C192S212000

Reexamination Certificate

active

06622834

ABSTRACT:

FIELD OF THE INVENTION
The invention generally concerns hydrodynamic torque converters.
BACKGROUND OF THE INVENTION
A conventional hydrodynamic torque converter typically includes a converter housing rotatably mounted on a shaft and which is connected to a drive and to a pump wheel or impeller. A turbine wheel is supported rotatably relative to the converter housing and is coupled to the shaft and hydrodynamically to the impeller. The torque converter further includes a bridging or lockup clutch to produce a friction coupling between a friction surface operably associated with the converter housing and a friction surface operably associated with the turbine.
Such a hydrodynamic torque converter can be used more particularly in a motor vehicle in order to transmit torque produced by an internal combustion engine to a transmission or to the wheels of the vehicle by way of a shaft. A typical torque converter of that general kind is to be found for example in WO 93/13338. The converter housing of that torque converter, which is mounted rotatably about the shaft as referred to above, is connected to a drive coming from the internal combustion engine, while in its interior it has the impeller or pump wheel that is fixedly connected to the converter housing. The arrangement of the turbine wheel which is supported rotatably on the shaft relative to the converter housing and a stator operatively disposed between the turbine and the impeller is such that, when the converter housing is rotated by the drive from the internal combustion engine, a hydrodynamic pressure is built up in the oil filling in the converter, and a circulatory flow of the oil by way of the impeller, the stator and the turbine takes place. Suitable shaping of the vanes of the impeller, stator and turbine, and supporting the stator by way of a freewheel unit, provides an increase in torque when the vehicle starts moving. In addition, the hydrodynamic coupling between the engine drive and the output shaft permits a gentle start without a clutch, and fluctuations in torque from the internal combustion engine can be appropriately damped.
The torque converter of above-mentioned WO 93/13338 also includes a bridging or lockup clutch. When the converter housing with the impeller and the turbine driven thereby with its shaft have reached approximately the same speed of rotation, the lockup clutch can be closed to produce a force-locking mechanical coupling between the converter housing and the shaft. In that way, in what is referred to as the clutch range in which the engine drive and the shaft are rotating at approximately the same speed, the hydrodynamic coupling, which suffers from an energy loss in that situation, is replaced by a mechanical coupling action. In that arrangement the lockup clutch is embodied by one or more friction surfaces with associated counterpart surfaces, of which one is associated with the converter housing and the other to the turbine. In order to engage the lockup clutch the two friction surfaces, which are disposed in mutually opposite relationship at an axial spacing in the inoperative condition of the clutch, are brought into contact with each other whereby the converter housing and the turbine are coupled together.
From the point of view of the structure involved, the lockup clutch in a torque converter as in WO 93/13338 is embodied by the provision of a disk-shaped member which is referred to as a piston and which is axially slidably supported on the shaft and non-rotatably connected to the converter housing. The piston has a first friction surface disposed thereon, which is in opposite relationship to a second friction surface provided on the converter housing.
Disposed between those two friction surfaces is a coupling element connected by way of a torsion damper to the turbine. In the opened or disengaged condition of the lockup clutch, the friction surfaces on the piston and the converter housing on the one hand and on the coupling element on the other hand are spaced from each other so that no coupling action takes place therebetween. In the closed or engaged condition of the lockup clutch on the other hand the piston is to be displaced axially towards the cover part of the converter housing which is at the engine side, and thereby clamps the coupling element disposed between it and the converter housing. As a result, the corresponding friction surfaces come into contact with each other so that the coupling element affords a force-locking frictional coupling effect between the converter housing and the turbine.
As already mentioned above, the coupling element in the torque converter of WO 93/13338 is coupled to the turbine by way of a torsion damper. That torsion damper comprises coil springs that extend in the peripheral direction of the converter and which are mounted to the outer shell portion of the turbine, one end of the coil springs being supported on the turbine and the other end on the coupling element. The springs are thus connected in serial relationship into the path of the flow of force from the coupling element to the turbine and provide that torque peaks and fluctuations originating from the drive or the converter housing can be appropriately damped and compensated as they are passed to the turbine and to the shaft respectively.
SUMMARY OF THE INVENTION
Therefore, a first object of the invention is to simplify the design of a hydrodynamic torque converter with lockup clutch so as to afford a more compact structure and reduced production costs together with a lower susceptibility to faults.
Another object of the present invention is to provide a hydrodynamic torque converter with lockup clutch which is of a more rational construction and an enhanced mode of operation with the elimination of some potential area of wear.
Still another object of the present invention is to provide a hydrodynamic torque converter incorporating a lockup clutch, so as to afford a mechanically simple operating procedure for engagement of the lockup clutch.
In accordance with the principles of the present invention, the foregoing and other objects are attained by a hydrodynamic torque converter including a converter housing which is rotatable about a shaft, and which is connected to a drive such as an internal combustion engine, and to an impeller. A turbine is supported rotatably relative to the converter housing, is coupled to the shaft, and is hydrodynamically coupled to the impeller. A lockup clutch produces friction coupling between a friction surface operably associated with the converter housing and a friction surface operably associated with the turbine. The turbine is axially slidably supported, whereby axial sliding movement of the turbine causes the friction surfaces to be brought into contact with each other.
As will be seen from a description hereinafter of preferred embodiments of the invention, the hydrodynamic torque converter according to the invention provides that an input torque coming from a suitable drive is hydrodynamically transmitted by way of the converter housing and the impeller to the turbine, which delivers the torque in converted mode to the output by way of the shaft. By way of the lockup clutch, mechanical coupling between the converter housing and the turbine can be produced in parallel with or alternatively to the hydrodynamic coupling condition, when the friction surfaces have been brought into contact with each other.
As in accordance with the invention, contact is made between those friction surfaces and thus the lockup clutch is closed by axial sliding movement of the turbine. Therefore, there is accordingly no need to provide an additional axially slidably mounted element, as referred to in the prior constructions, and this elimination of such an element can reduce the structural complication and expenditure, and thus reduce the production costs of the torque converter, avoid a potential wear point, and make it possible for the torque converter to be of a more compact configuration.
In this respect, the hydrodynamic coupling action which may possibly occur be

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