Hydrodynamic coupling device

Details Hydrodynamic coupling device Hydrodynamic coupling device

2000-08-11

2002-12-24

Lorence, Richard M. (Department: 3681)

192 clutches and power-stop control

Vortex-flow drive and clutch

Including drive-lockup clutch

C192S10700R, C192S113360

Reexamination Certificate

active

06497312

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydrodynamic coupling device, in particular a torque converter. The interior of the hydrodynamic coupling device may be separated into a first fluid space and a second fluid space by means of a clutch element comprising a lockup clutch and a friction surface arrangement. The clutch element is capable of being pressed up to a housing or a component connected to the housing, with the friction surface arrangement interposed. In the friction surface arrangement is a fluid duct arrangement, into which working fluid can flow from the first fluid space and out of which working fluid can flow only toward the first fluid space. Working fluid is supplied to the first fluid space by means of a first connecting duct arrangement and working fluid is led into and/or out of the second fluid space by means of a second connecting duct arrangement.
2. Description of the Related Art
A hydrodynamic coupling device is known from EP 0 428 248 A1. The lockup clutch of this coupling device, designed as a hydrodynamic torque converter has, a clutch piston which is capable of being pressed in the radially outer region against a housing cover. A ring-like friction lining is interposed as a friction surface arrangement. Provided in the ring-like friction lining are axially continuous fluid flow ducts which extend radially outward at an angle. Working fluid can flow out of a fluid space of the torque converter into the axially continuous fluid flow ducts through a passage orifice in the piston and is then discharged radially outward again into a region of the same fluid space. Cooling of the friction lining in the traction slip mode is thereby ensured by means of a flow generated by interaction of centrifugal force effects and shear fluid effects. At the same time, care is taken to ensure that no working fluid cooling the friction lining can flow into a fluid space formed between the piston and the housing cover, so that the coupling efficiency of the lockup clutch is not impaired.
An embodiment of this type has proved advantageous in terms of maintaining a high degree of coupling efficiency of the lockup clutch. However, the problem with this arrangement is that the working fluid flowing into the same fluid space again does not participate in an overall fluid exchange. Therefore, various structural measures, for example external cooling by means of cooling ribs or the like, must be taken to ensure that the entire torque converter does not gradually heat up.
SUMMARY OF THE INVENTION
The object of the present invention is to develop a generic hydrodynamic coupling device in such a way that, along with a high degree of coupling efficiency, good cooling of the entire system is ensured.
The present invention is a hydrodynamic coupling device including a housing, a lock up clutch, a friction surface mechanism, a fluid duct means and three connecting duct means. The lock up clutch has a clutch element arranged in the housing and may be pressed toward the housing. The friction surface mechanism is arranged between the clutch element and the housing. The clutch element and the friction surface mechanism separate an interior of the hydrodynamic coupling device into a first fluid space and a second fluid space. The fluid duct means is in the friction surface mechanism and permits the working fluid to flow into and out of the first fluid space while preventing the working fluid from flowing out of the first fluid space into the second fluid space. The connecting duct means are in the fluid duct means, with the first connecting duct means being capable of permitting flow of the working fluid to the first fluid space, and the second connecting duct means being capable of permitting flow of the working fluid into and out of the second fluid space. The third connecting duct means is capable of circulating the working fluid within the first fluid space before permitting the working fluid to flow out of the first fluid space, at least when the clutch element is pressed up toward the housing with the friction surface arrangement interposed between them.
The present invention ensures that, even though the cooling flow over the friction surface arrangement is generated solely as a result of the inclusion of the first fluid space, the heated working fluid can flow out of the interior at least partially and can be replaced by colder working fluid. Even in a lengthy traction slip mode, in which fluid exchange is otherwise not ensured due to the fluid pressure being maintained in the interior of the coupling device, cooling is achieved.
For example, a turbine wheel may be arranged rotatably about an axis of rotation in the first fluid space. The first connecting duct arrangement and the third connecting duct arrangement may be connected to the first fluid space on axial sides of the turbine wheel, in particular of a turbine wheel shell. The axial sides of the turbine wheel are opposite one another with respect to the axis of rotation. Preferably, the third connecting duct arrangement is connected to the first fluid space in a region between the turbine wheel (in particular a turbine wheel shell) and the clutch element (or clutch piston). As a result, working fluid that has flowed into the first fluid space cannot immediately flow out of the first fluid space again through the third connecting duct arrangement, without having participated at least partially in a circulating action.
The third connecting duct arrangement in a turbine wheel hub may comprise at least one first fluid passage orifice extending essentially radially. An output shaft may be provided so that fluid can be supplied in a simple way to the second fluid space and fluid can be discharged from the latter. The output shaft has a second fluid passage orifice which extends essentially in the direction of an axis of rotation and which forms at least part of the second connecting duct arrangement.
To obtain a very simple design, in which three completely separately activatable connecting duct arrangements do not have to be provided, i.e. in a 3-line system, the second connecting duct arrangement and the third connecting duct arrangement are connected to one another in a radially inner region. For example, this may be achieved by opening the third connecting duct arrangement into the second fluid passage orifice.
At least one passage orifice for leading working fluid into the fluid duct arrangement may be provided in the clutch element. Preferably, at least one outflow orifice for leading working fluid out of the fluid duct arrangement into the first fluid space is provided in the clutch element. Thus, the working fluid also flows into the first fluid space again in the region, or at the side of the clutch element, out of which it previously flowed into the fluid duct arrangement. This is advantageous, in particular, when this region of the first fluid space is also in fluid exchange connection with the third connecting duct arrangement.
In order to use the shear effects or frictional effects occurring during the flow through the fluid duct arrangement, an inflow orifice and an outflow orifice, which are assigned to the same fluid duct portion of the fluid duct arrangement, are offset relative to one another in the circumferential direction. Preferably, the friction surface arrangement is movable in the circumferential direction with respect to at least one subassembly of clutch element and housing or to a component connected to it, while the fluid duct arrangement comprises a groove-like duct arrangement which is open on a friction surface of the friction surface arrangement, the friction surface interacting with the at least one subassembly.
The shear or friction action may be utilized with the greatest possible efficiency if the fluid duct arrangement comprises at least one fluid duct region which extends essentially only in the circumferential direction.
The present invention further relates to a friction surface arrangement for a hydrodynamic coupling device, in which the fri

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