This application claims priority from German patent application serial no. 10 2020 208 351.7 filed Jul. 3, 2020.

FIELD OF THE INVENTION

The invention relates to a hydrodynamic torque converter with a torsion damper.

BACKGROUND OF THE INVENTION

Hydrodynamic torque converters are clutches that work in accordance with the Föttinger principle. Owing to their virtually wear-free operating mode they are used in many technical fields for the transmission of rotation movements. These torque converters often have a converter bridging clutch, also known just as a “bridging clutch” for short. This serves to make it possible to bridge the otherwise hydrodynamic clutch of the converter, where necessary, by means of a mechanical clutch. In that way flow losses in the converter can be minimized.

In automotive technology hydrodynamic torque converters are often used as a starting clutch and/or as an integral transmission shifting element. The torque converter is in this case provided as an input-side or a central shifting element of a multi-stage motor vehicle transmission. Thus, the torque converter is connected to the transmission by the action of torque. In the hydrodynamic operation of the torque converter a drive input power is transmitted by means of hydraulic fluid. This takes place virtually without wear, so that it is the hydraulic fluid which predominantly absorbs the heat losses generated thereby. For that reason the torque converter is often connected to a cooling system of the transmission and/or the motor vehicle. Heat energy is produced in particular in the hydrodynamic torus of the converter and by friction work in the bridging clutch.

Hydrodynamic torque converters normally have a low-pressure side (suction side) and a high-pressure side (pressure side). In many transmission arrangements, for design reasons the feed line for hydraulic fluid to the converter cannot be arranged on the suction side of the latter and the return line for the hydraulic fluid from the converter cannot be arranged on its pressure side. The lines are then arranged elsewhere on the converter. Consequently heat can accumulate inside the converter and this can result in damage to temperature-sensitive converter components. Exceeding acceptable temperatures in the converter can also result in increased wear of the bridging clutch and heating of the hydraulic fluid.

From DE 10 2005 051 739 A1 a hydrodynamic torque converter with a bridging clutch and a torsion damper is known. The bridging clutch is intended to show constant behavior over a very long lifetime. For this, direct cooling of the clutch disks of the bridging clutch through an axial piston of the converter and the torsion damper is proposed.

DE 10 2007 005 999 A1 also discloses a hydrodynamic torque converter. In this case leakage flows that affect the cooling adversely and undesired friction effects are to be avoided. For that purpose a pressure chamber on the drive output side is delimited by the drive output side of the clutch piston and by a partition wall associated with the clutch piston. For its part, the partition wall acts between the pressure chamber on the drive output side and a cooling chamber.

From DE 20 2006 020 596 U1 a hydrodynamic torque converter with a bridging clutch and a damper is known. In this case the intention is to improve an oil flow over friction surface of the disks of the bridging clutch in order to improve the cooling of the disks. For this, the circulation oil flow in the area of the hydrodynamic structural elements of the converter (pump, turbine, guide wheel) should still flow to and from the disks. For that purpose an additional wall is fitted on the side of the clutch piston that faces away from the piston pressure space.

When the oil flow in a hydrodynamic torque converter takes place from the torus to the bridging clutch, for example as indicated by arrows in the figures of DE 20 2006 020 596 U1, the bridging clutch, besides the friction heat generated there, takes up additional heat from the oil flow. Thus, most of all during slipping operation of the bridging clutch there can be unacceptably high heat intake by the bridging clutch. This can result in damage to the bridging clutch. Such damage can mainly affect friction linings of the bridging clutch, since these often consist of friction-lining paper.

SUMMARY OF THE INVENTION

The purpose of the present invention is to improve upon the prior art. In particular, good cooling of the bridging clutch of the torque converter should be enabled while keeping the production costs of the torque converter low.

This objective is achieved by the measures specified in the principal claim. Preferred embodiments thereof emerge from the subordinate claims.

According to these a hydrodynamic torque converter is proposed, which comprises a pump wheel, a turbine wheel and a torsion damper. The pump wheel, turbine wheel and torsion damper are in particular accommodated inside a housing of the converter. In particular, the pump wheel is positionally fixed in the housing. The pump wheel and the turbine wheel form a torus for hydraulic fluid. The turbine wheel can rotate relative to the pump wheel. There is an intermediate space between the turbine wheel and the torsion damper.

The torque converter can transmit a torque hydrodynamically by way of the hydraulic fluid from its input to its output. Depending on the design and operating point of the converter, it is also possible for the converter to increase the torque delivered from its output side compared with the torque applied at its input side.

The torsion damper serves to damp torsion fluctuations between the input and output sides of the torsion damper, in particular due to non-uniform rotation behavior of an internal combustion engine on the input side. In that way torsion fluctuations applied on the input side are not passed on to the output side, or only so after being damped.

In the torque converter proposed, it is now provided that a flow-guiding wall is arranged in the housing. This wall is specially designed to deflect a flow of the hydraulic fluid emerging radially outward from the torus during the operation of the torque converter, radially inward toward the intermediate space. The result is that at least most of the hydraulic fluid flow emerging radially outward from the torus passes into the intermediate space.

The hydraulic fluid previously heated in the torus can now be simply removed from the intermediate space. In particular, for this an outlet opening for the hydraulic fluid is provided in the area of the intermediate space. Thus, the hydraulic fluid of the torus no longer reaches particularly temperature-sensitive structural elements of the torque converter, or only so to a slight extent, such elements including in particular the converter bridging clutch. The bridging clutch is usually located on the side of the torsion damper facing away from the turbine wheel, i.e. on the other side of the intermediate space.

In particular, the torque converter thus also comprises the bridging clutch. To actuate the bridging clutch a hydraulic piston is preferably provided. For that, the piston has in particular a pressure side which can be acted upon by a hydraulic pressure. In that way an actuating force is exerted on the bridging clutch. The actuating force is reduced by decreasing the hydraulic pressure. In this way the clutch can be optionally closed and opened. When the bridging clutch is fully closed, the hydrodynamic power branch of the torque converter is bypassed (deactivated) in drive-technological terms, so that the torque on the input side is transmitted via the bridging clutch to the output of the converter. When the bridging clutch is fully open only the hydrodynamic power branch of the converter is activated, whereby a torque on the input side is transmitted to the output purely hydrodynamically. When a frictional bridging clutch is used, especially such as a disk clutch, intermediate settings between the fully open and fully closed positions can also be produced, whereby the torque on the input side is transmitted to the output partially by the bridging clutch and partially hydrodynamically.

The torsion damper of the converter is in particular arranged in the power branch of the bridging clutch, so that the torsion fluctuations introduced by the bridging clutch are damped. It can be provided that the torsion damper does not act in the hydrodynamic power branch.

Preferably, the flow-guiding wall is annular or bowl-shaped. It has a central opening positioned in the intermediate space. Thus, the flow-guiding wall can be made inexpensively.

In particular, the flow-guiding wall is made by deformation technology, in particular by pressing. Thus, the wall can be a cheap sheet component.

Preferably, the flow-guiding wall is a separate structural element for deflecting the flow of hydraulic fluid radially inward into the intermediate space. In particular, that is the only purpose of the separate structural element. Consequently, the flow-guiding wall can be made simply. It can be attached to other structural elements of the torque converter. In particular, the flow-guiding wall is welded or riveted or adhesively bonded to these other structural elements.

Alternatively, it is possible for the flow-guiding wall to be an integral part of some other, in any case necessary structural element of the torque converter. For example, the flow-guiding wall can be an integral part of the torsion damper or of the housing. The flow-guiding wall can then be in the form of a special rib or shoulder on the in any case necessary structural element of the torque converter.

Particularly preferably, the flow-guiding wall is suspended on the housing of the torque converter. Thus, the flow-guiding wall is supported by the housing. In that case the flow-guiding wall can be the separate structural element, which can then be fixed directly onto the housing.

The housing of the converter comprises in particular a (first) housing component, which accommodates the blades of the pump wheel. This housing component is in particular a rear half of the housing. The housing of the converter comprises in particular a (second) housing component which accommodates the torsion damper and/or the bridging clutch. This housing component is in particular a front half of the housing. Thus, the housing is essentially made in two parts.

The blades that form the pump wheel are preferably attached directly to the (first) housing component. Thus, this housing component at the same time forms the pump wheel. It can now be provided that the flow-guiding wall is suspended on the pump component. Alternatively, it can be provided that the flow-guiding wall is suspended on the (second) housing component, the one which accommodates the torsion damper and/or the bridging clutch. In that case the flow-guiding wall is preferably attached to the respective housing component. In that way the converter can be made inexpensively.

In particular, the two housing components are solidly connected to one another in a connection area, for example welded together. The flow-guiding wall can be suspended on this connection area. In particular the flow-guiding wall can be made as a separate structural element and be clamped between the two housing components in the connection area. In that way, when the housing components are joined together, the flow-guiding wall can be fixed to the housing at the same time.

Preferably, the outlet opening for the hydraulic fluid is arranged radially inside the intermediate space and between the torsion damper and the pump wheel. This allows hydraulic fluid to be discharged from the torque converter. An inlet opening for the hydraulic fluid can be arranged radially inside, on the other side of the torsion damper. In that way relatively cool hydraulic fluid is guided from the inlet opening, along one side of the torsion damper, to the bridging clutch, while the relatively hot hydraulic fluid from the torus is guided along the other side of the torsion damper to the outlet opening. Thus, a confluence of these flows is prevented as much as possible. The cooling of the bridging clutch is ensured. Here, the turbine wheel also located between the torsion damper and the pump wheel has in particular at least one opening, through which there is a connection for the hydraulic fluid from the intermediate space to the outlet opening. This enables the flow of the relatively hot hydraulic fluid out of the intermediate space to the outlet opening.

The inlet opening is in particular arranged in the radially inner area between the piston for actuating the bridging clutch and the torsion damper. Thus, during the operation of the torque converter hydraulic fluid passes into the converter in order to cool and lubricate the bridging clutch. The hydraulic fluid flows from the inlet opening radially outward to the bridging clutch. In particular, the inlet opening is designed to guide hydraulic fluid coming from a radially internal driveshaft into the intermediate space. The driveshaft is in particular a transmission input shaft.

Preferably, the bridging clutch is arranged on one side of the torsion damper between the housing on one side and the torsion damper on the other side. In this case the intermediate space is arranged on the other side of the torsion damper between the turbine wheel on one side and the torsion damper on the other side. The torsion damper has a torsion damper wall which guides the hydraulic fluid radially inward into the intermediate space. Thus, the torsion damper wall directs the flow of hydraulic fluid along the intermediate space in the direction toward the outlet opening. The torsion damper wall precludes an unacceptably large quantity of the relatively hot hydraulic fluid from flowing out of the intermediate space through the torsion damper to the bridging clutch. In this case the torsion damper wall is in particular positioned on the side of the torsion damper facing the intermediate space.

Preferably, this torsion damper wall screens the bridging clutch, at least or only in a radially outer area of the torsion damper, from the radially outward flow of hydraulic fluid coming from the torus. For example, in this radially outer area of the torsion damper a damper plate can be provided, which in that position prevents the passage of hydraulic fluid from the intermediate space through the torsion damper. It can be provided that in this radially outer area of the torsion damper, first curved springs are arranged on a common circumference or circumferential area. In the area of the curved springs conventional torsion dampers for hydrodynamic torque converters have window-like openings for the curved springs. By the torsion damper wall these openings are now closed for the hydraulic fluid, for example in that the openings are covered by the torsion damper wall.

In particular, the housing of the torque converter serves as the inlet of the torque converter. In this case the turbine wheel is arranged rotatably inside the housing and is connected rotationally fixed to the output side of the torsion damper. Here, the output side of the torsion damper serves as the drive output of the torque converter and is designed to be connected in a rotationally fixed manner to a radially inner driveshaft, in particular such as a transmission input shaft. The bridging clutch of the converter has an inlet connected rotationally fixed to the housing and an outlet connected rotationally fixed to the input side of the torsional damper. The input and output sides of the bridging clutch can optionally be connected rotationally fixed to one another and rotatably released from one another by moving the piston. The torsion damper, the bridging clutch and the piston are in particular also accommodated in the housing, in particular in the second housing component. The pump wheel is then in particular accommodated in the first housing component.

Optionally, a vehicle transmission is also proposed which comprises the proposed hydrodynamic torque converter. The transmission has a transmission input shaft by means of which a drive input torque can therefore be delivered to the transmission. The output of the torque converter is connected rotationally fixed to the transmission input shaft, and in particular the converter is arranged on the transmission input shaft. The motor vehicle transmission can be a multi-stage transmission. The transmission then has a plurality of selectable gear ratios by means of which, in each case, a torque applied on the input side can be transmitted, geared up or down, to the transmission output. In other words, the proposed hydrodynamic torque converter is specially designed to be installed in a motor vehicle transmission.

Preferred properties and advantages of the proposed hydrodynamic torque converter can be:defined, targeted guiding of the hydraulic fluid in the torque converter;prevention of flooding of the bridging clutch with hot hydraulic fluid directly from the torus gap, and thus prevention of thermal overheating of the bridging clutch;reduction of the wear of friction linings of the bridging clutch;simple design implementation, for example as a sheet-metal design and/or as a welded structure and/or as a component produced by deformation;less additional fitting space required and lower weight;low costs.

