Abstract:
A vehicle transmission torque converter assembly, having: an engine output shaft; a turbine; and a transmission input shaft linkable to either the engine output shaft or turbine via a lock-up clutch. The lock-up clutch is configured to sustain the transmission input shaft being: (i) coupled to the engine output shaft; (ii) coupled to the turbine; or (iii) decoupled.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation and claims the benefit of German Patent Application No. DE 102012205535.5 titled “Torque Converter for Motor Vehicle” filed Apr. 4, 2012, which is hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention relates to vehicle transmission torque converters having a lock-up clutch between an engine output shaft and a transmission input shaft. 
       BACKGROUND 
       [0003]    Some existing automatic transmission designs disclose a torque converter that has an additional clutch with which a transmission input shaft can be uncoupled from a torque converter turbine in order to prevent drag losses during idling, e.g., in the case of a hybrid drive mode. The additional clutch, however adds parts and weight to the vehicle. 
         [0004]    Therefore, it is desirable to have a torque converter with a sustainable stage that decouples the transmission input shaft from the turbine and engine output shaft without the need for an additional clutch. 
       SUMMARY 
       [0005]    The present disclosure addresses one or more of the above-mentioned issues. Other features and/or advantages will become apparent from the description which follows. 
         [0006]    One advantage of the present disclosure is that it teaches a torque converter with a sustainable stage that decouples the transmission input shaft from the turbine and engine output shaft without the need for an additional clutch. 
         [0007]    Another advantage of the present disclosure is that it teaches a torque converter that makes it possible to control a lock-up clutch to be decoupled from the turbine in order to enable engine idling with minimal losses and a smooth transition between drive operation and idling operation. 
         [0008]    One exemplary embodiment of the present disclosure relates to a vehicle transmission torque converter assembly, having: an engine output shaft; a turbine; and a transmission input shaft linkable to either the engine output shaft or turbine via a lock-up clutch. The lock-up clutch is configured to sustain the transmission input shaft being: (i) coupled to the engine output shaft; (ii) coupled to the turbine; or (iii) decoupled. 
         [0009]    Another exemplary embodiment of the present disclosure relates to a vehicle transmission torque converter assembly, including: a three stage lock-up clutch with a sustainable stage where the transmission input shaft is decoupled from an engine output shaft and a torque converter turbine. 
         [0010]    The invention will be explained in greater detail below by way of example with reference to the figures, in which the same reference numbers are used in the figures for identical or essentially identical elements. The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. In the figures: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows a cross-sectional view through a torque converter in a state in which the transmission input shaft is coupled to an engine output shaft; 
           [0012]      FIG. 2  shows a cross-sectional view through a torque converter in a state in which the transmission input shaft is coupled to a turbine; and 
           [0013]      FIG. 3  shows a cross-sectional view through a torque converter in a state in which the transmission input shaft is not coupled. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to the drawings, wherein like characters represent examples of the same or corresponding parts throughout the several views, there is shown an exemplary torque converter assembly for a vehicle transmission. The exemplary illustrated torque converter assembly is advantageous in that the torque converter has a sustainable stage that decouples a transmission input shaft from a torque converter turbine and engine output shaft without the need for an additional clutch. 
         [0015]    Referring now to  FIGS. 1-3 , there is shown in each a cross-section through an exemplary vehicle transmission torque converter or torque converter assembly  10  that is substantially rotationally symmetrical about a central axis  12 . Torque converter  10  contains an engine output shaft  14  and a transmission input shaft  16  that extend along central axis  12 , a pump wheel  18  that is rotatably mounted about a transmission input shaft  16  and connected in a rotationally conjoint manner via a converter housing  20 . Housing  20  is also rotatably mounted about transmission input shaft  16 , to engine output shaft  14 . A turbine  22  is rotatably mounted about transmission input shaft  16 , a guide wheel  24  and a lock-up clutch. 
         [0016]    The lock-up clutch, of  FIGS. 1-3 , contains a substantially disc-shaped clutch element  26  that extends annularly around transmission input shaft  16  and is connected in a rotationally conjoint manner thereto by means of a multi-tooth connection that simultaneously enables an axial displacement with respect to transmission input shaft  16 . Disc-shaped clutch element  26  has an annular, radially external portion  28  that lies between a first frictional surface  30  formed on an inner surface of converter housing  20  and a second frictional surface  32  connected fixedly to turbine  22 . In each case annular radially external portion  28  can touch one of the two frictional surfaces  30 ,  32  or neither of these when disc-shaped clutch element  26  is axially moved (as shown in  FIG. 3 ). Frictional surface  32  is connected to turbine  22  and is supported by an annular projection or chamber  48  that extends from the outside of turbine  22  in the direction of the radially external portion  28  of clutch element  26 . A torsional damper  34  is integrated into clutch element  26 . The lock-up clutch comprises parts labeled as  26 ,  28 ,  30 ,  32  and  34 . 
         [0017]    Transmission input shaft  16  is embodied as a hollow shaft and contains a first central fluid channel  36  through which hydraulic fluid that is under a converter charging pressure (or “CC”) can be supplied from a first fluid connection  38  on one hand to pump wheel  18  and on the other hand to a chamber  40  between converter housing  20  and disc-shaped clutch element  26  or conducted away therefrom. A hollow shaft  42  extends annularly around an axial portion of transmission input shaft  16 . Transmission input shaft  16  and hollow shaft  42  delimit a second radial fluid channel  44  between them through which hydraulic fluid that is under converter discharging pressure (or “CDC”) can be supplied from a second fluid connection  46  on one hand to guide wheel  24  and on the other hand to a chamber  48  between turbine  22  and disc-shaped clutch element  26  or conducted away therefrom. A two-channel hydraulic fluid guide can alternatively be formed with two radial fluid channels instead of with a central fluid channel  36  and a radial fluid channel  44 . 
         [0018]    If converter charging pressure is lower than converter discharging pressure, radially external portion  28  of disc-shaped clutch element  26  is pressed against frictional surface  30  internally on converter housing  20 , as shown in  FIG. 1 , and torque converter  10  is in a lock-up state or stage. In this state, the output torque is precisely equal to the input torque, i.e. equal to the torque of the internal combustion engine that drives engine output shaft  14 . Hydraulic fluid flows in through the second fluid connection  46  and out through the first fluid connection  38 . 
         [0019]    If converter charging pressure is higher than converter discharging pressure, radially external portion  28  of disc-shaped clutch element  26  is pressed against frictional surface  32  fixed on the turbine, as shown in  FIG. 2 , and torque converter  10  is located in an operating state with torque conversion. In this state, the output torque is equal to the input torque multiplied by a torque conversion factor. Hydraulic fluid flows in through the first fluid connection  38  and out via second fluid connection  46 . 
         [0020]    If converter charging pressure is equal to converter discharging pressure, radially external portion  28  of disc-shaped clutch element  26  can rotate freely between frictional surfaces  30  and  32 , as shown in  FIG. 3 , and torque converter  10  is located in a state in which the torque converter does not transmit any torque. In this state as well no hydraulic fluid flows through torque converter  10 . 
         [0021]    The lock-up clutch forms a type of two-way clutch that couples the transmission input shaft either to the engine output shaft or to the turbine or to neither of these two. The torque converter disclosed can thus have less packaging space, parts and weight than contemporary designs. It is also possible to integrate the torque converter into existing engine series that have been designed for torque converters without the possibility of uncoupling of the transmission input shaft. 
         [0022]    In one embodiment, the lock-up clutch has a torsional damper where the torsional damper can be integrated into the disc-shaped clutch element. 
         [0023]    Those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.