Patent Publication Number: US-2023134624-A1

Title: Torque converter with multi-plate clutch assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 63/274,249, filed Nov. 1, 2021, the disclosure of which is incorporated in its entirety by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a torque converter for a vehicle. In particular, the disclosure is related to a multi-plate clutch assembly of a torque converter. 
     BACKGROUND 
     Many vehicles include a launch device between the engine and the transmission. A torque converter is a type of launch device commonly used in vehicles having an automatic transmission. A typical torque converter includes an impeller fixed to the crankshaft of the engine and a turbine fixed to a turbine shaft, which is the input to the transmission. To improve fuel economy, most torque converters include a bypass or lock-up clutch that mechanically couples the turbine shaft to a cover of the torque converter to bypass the fluid coupling. In some arrangements, the lock-up clutch may have a clutch plate riveted to a front cover of the torque converter. Due to limited spacing within a torque converter envelope, it is desirable to have alternative designs and configurations to fit all the necessary components within the torque converter while still meeting durability and performance requirements. 
     SUMMARY 
     In one embodiment, a torque converter comprises a front cover configured to receive a torque and an impeller having an impeller shell non-rotatably connected to the front cover. A turbine is fluidly coupled to the impeller and includes a turbine shell. A lock-up clutch is provided that includes a piston configured to axially displace to engage and disengage the lock-up clutch; a first clutch plate and a second clutch plate connected to each other, the first and second clutch plates being disposed between the piston and front cover; and a flexible clutch plate disposed axially between the first and the second clutch plates and connected to the piston. 
     In embodiments, the torque converter may further include a leaf spring connected to the piston radially inside of the first and second clutch plates. The intermediate clutch plate may be connected to the leaf spring at a radially inner end thereof. The leaf spring may be, at least partially, disposed axially between the piston and the intermediate clutch plate. The intermediate clutch plate, the leaf spring, and the piston may be connected to each other via a riveted connection. 
     In embodiments, the intermediate clutch plate may be connected to the piston radially inside of the first and second clutch plates. In embodiments, the intermediate clutch plate may be connected to the piston at a radially inner end thereof. In embodiments, the first clutch plate may be connected to the second clutch plate radially outside of the intermediate clutch. In embodiments, the first clutch plate may be connected to the second clutch plate radially outside of the piston. In embodiments, the intermediate clutch may be configured to bend relative to the piston during operation of the lock-up clutch. 
     In embodiments, the torque converter may further include a damper assembly having an output flange and a cover plate disposed axially between the piston and the output flange. The first clutch plate may be connected to the cover plate. 
     Embodiments of this disclosure further provide a lock-up clutch for a torque converter. The lock-up clutch includes a piston configured to axially displace to engage and disengage the lock-up clutch; a first clutch plate and a second clutch plate connected to each other; and a flexible clutch plate disposed between the first and the second clutch plates and connected to the piston. 
     In embodiments, the lock-up clutch may further include a leaf spring connected to the piston radially inside of the first and second clutch plates. The intermediate clutch plate may be connected to the leaf spring at a radially inner end thereof. The leaf spring may be, at least partially, disposed axially between the piston and the intermediate clutch plate. The intermediate clutch plate, the leaf spring, and the piston may be connected to each other via a riveted connection. 
     In embodiments, the intermediate clutch plate may be connected to the piston radially inside of the first and second clutch plates. In embodiments, the intermediate clutch plate may be connected to the piston at a radially inner end thereof. In embodiments, the first clutch plate may be connected to the second clutch plate radially outside of the intermediate clutch. In embodiments, the first clutch plate may be connected to the second clutch plate radially outside of the piston. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The single FIGURE is a cross-sectional view of a torque converter having a multi-plate clutch assembly according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
     In some torque converter arrangements, it may be challenging and difficult to connect and center a second outer clutch plate of a multi-plate lock-up clutch assembly to the torque converter due to limited packaging and space constraints. Additionally, because of the multi-plate design, it is required that all clutch plates have relative motion where required to generate the required friction. Embodiments described herein provide a multi-plate clutch assembly with a flexible, intermediate clutch plate attached directly to a leaf spring package and a piston of a torque converter. Embodiments according to the present disclosure provide several advantages including providing a multi-plate clutch assembly for torque converters with space constraints as described above. 
     Referring to the single FIGURE, a portion of torque converter  100  is illustrated according to one embodiment of the present disclosure. At least some portions of torque converter  100  are rotatable about central axis  102 . While only a portion above central axis  102  is shown in the single FIGURE, it should be understood that the torque converter can appear substantially similar below central axis  102  with many components extending about central axis  102 . Words such as “axial,” “radial,” “circumferential,” “outward,” etc. as used herein are intended to be with respect to central axis  102 . 
     Torque converter  100  includes: front cover  104  arranged to receive torque; impeller  106 ; turbine  114 ; and a lock-up clutch  126 . Impeller  106  includes: impeller shell  108  non-rotatably connected to front cover  104  such that impeller  106  rotates as front cover  104  rotates, at least one impeller blade  110  attached to an inner surface of impeller shell  108 , and impeller hub  112  attached to a radially inner end of impeller shell  108 . Turbine  114  includes turbine shell  116  and at least one turbine blade  118  attached thereto. Turbine shell  116  may be connected to output hub  144  for torque transmission therebetween. By “non-rotatably connected” components, we mean that: the components are connected so that whenever one of the components rotate, all the components rotate; and relative rotation between the components is not possible. Radial and/or axial movement of non-rotatably connected components with respect to each other is possible, but not required. 
     Torque converter  100  may include: stator  122  disposed axially between impeller  106  and turbine  114  to redirect fluid flowing from turbine blade  118  before fluid reaches impeller  106  to increase an efficiency of torque converter  100 . For example, impeller blade  110  when rotated about central axis  102 , pushes the fluid outwardly. The fluid pushes against turbine  114  of torque converter  100 , causing turbine  114  to revolve about central axis  102 . Stator  122  functions to return the fluid from turbine  114  back to impeller  106  with minimal or no power loss. Drive power is transmitted from turbine  114  to an input shaft of the transmission (not shown). Torque converter  100  may further include: one-way clutch  134  disposed within stator  122 , thrust bearing  136  disposed axially between stator  122  and turbine shell  116  and thrust bearing  138  disposed axially between stator  122  and impeller shell  108 , and side plate  140  configured to retain the one-way clutch  134  within the stator  122 . 
     Torque converter  100  also includes damper assembly  124  for hydraulically transferring torque through torque converter  100 . Damper assembly  124  is positioned axially between front cover  104  and turbine  114  and may be configured to transfer torque from front cover  104  to output hub  144 . Damper assembly  124  may include input cover plate  146 , input cover plate  148 , springs  150 , and output flange  152 . Input cover plate  146  may support springs  150  on one axial side. Input cover plate  148  may support springs  150  on another, opposite axial side. Output flange  152  may be connected to output hub  144  for torque transmission therebetween. Output flange  152  may be connected to turbine shell  116 , e.g., via a connector such as a rivet. 
     Power from a vehicle engine (not shown) can be transmitted to a transmission via fluid, and via the torque converter. In particular, the power may first be transmitted to front cover  104  of torque converter  100 . Lock-up clutch  126  is configured to selectively transfer torque from front cover  104  to output hub  144 . Lock-up clutch  126  includes piston  128 , clutch plate  130 , clutch plate  132 , and clutch plate  142 . 
     Clutch plate  130  and clutch plate  142  may be connected to one another (e.g., via a tabbed connection) and act as outer clutch plates, with clutch plate  130  directly connected to an input of damper assembly  124 . For example, clutch plate  130  may be drivingly connected to input cover plate  146  to transfer torque thereto, e.g., via a tabbed connection. Clutch plate  132  may be disposed axially between clutch plates  130 ,  142  and connected at an inner end to piston  128  and leaf springs  120 , for example, via a connector such as a rivet. Leaf springs  120  allows axial displacement of piston  128  relative to front cover  104 . Clutch plate  132  may be designed as a flexible clutch plate and referred to herein as flexible clutch plate  132 . During the overbend process, clutch plate  132  is configured to move together and relative to piston  128 , returning back to its working position after the riveting. 
     Piston  128  may be sealed to output hub  144  at an inner diameter thereof and configured to axially displace toward and away from front cover  104  to engage (close) and disengage (open) lock-up clutch  126 . Clutch plate  130  may be disposed, at least partially, between front cover  104  and flexible clutch plate  132 , and clutch plate  142  may be disposed between flexible clutch plate  132  and piston  128 . Friction paper or rings may further be attached to front cover  104 , clutch plate  130 , flexible clutch plate  132 , clutch plate  142  and/or piston  128 . For example, friction materials (facings) may be attached to outer clutch plates  130 ,  142  and flexible clutch plate  132  may act as friction surface for the friction facings. 
     For the clutch release and apply function of lock-up clutch  126 , clutch plate  132  is designed as a flexible clutch plate. That is, clutch plate  132  is bendable relative to piston  128 , e.g., during operation of lock-up clutch  126 . For example, clutch plate  132  may be formed from material such as  1074 / 1075  steel. The clutch plate  132  is designed to allow axial conformity between piston  128  and clutch plate  132 . For example, holes may be provided in clutch plate  132 , e.g., in various geometries, to reduce rigidity of the clutch plate  132  and thereby achieve a desired flexibility relative to piston  128 . Additionally, or alternatively, a taper may be added to clutch plate  132 , which can reduce or avoid undesirable drag torque during the release process of lock-up clutch  126 . 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications. 
     LIST OF REFERENCE NUMBERS 
       100  torque converter 
       102  central axis 
       104  front cover 
       106  impeller 
       108  impeller shell 
       110  impeller blade 
       112  impeller hub 
       114  turbine 
       116  turbine shell 
       118  turbine blade 
       120  leaf springs 
       122  stator 
       124  damper assembly 
       128  piston 
       130  clutch plate 
       132  clutch plate 
       134  one-way clutch 
       136  thrust bearing 
       138  thrust bearing 
       140  side plate 
       142  clutch plate 
       144  output hub 
       146  input cover plate 
       148  input cover plate 
       150  springs 
       152  output flange