Abstract:
A torque transmitting assembly for selectively transmitting torque between a first member and a second member includes a plate clutch interconnected between the first member and the second member, the plate clutch having a maximum torque capacity limited to enabling full throttle single-transition up-shifts in the transmission when the plate clutch is fully engaged. A dog clutch is connected to the first member and selectively connected to the second member. The dog clutch is in frictional engagement with the plate clutch when the plate clutch is engaged, and the dog clutch is connected to the second member prior to the transmitted torque exceeding the maximum torque capacity of the plate clutch.

Description:
FIELD 
     The invention relates generally to a torque transmitting device having a dog clutch and a plate clutch, and more particularly to a torque transmitting device having a dog clutch and a minimum capacity plate clutch to provide power-on upshifts. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     A typical multi-speed automatic or hybrid transmission uses a combination of torque transmitting devices, such as clutches or brakes, to achieve a plurality of forward and reverse gear or speed ratios. Selection of speed ratios is typically accomplished by a microprocessor transmission control module that employs various vehicle parameters, for example vehicle speed, and various driver input signals, for example accelerator pedal position, to select the appropriate speed ratios. The transmission then engages a combination of the toque transmitting devices to provide the desired speed ratios. 
     These torque transmitting devices generally include plate clutches or dog clutches typically used in manual transmissions. Plate clutches are typically designed for sufficient torque capacity for all engaged operating conditions of the transmission and are accordingly robust. However, typical plate clutches often require substantial packaging space and may create problems with smooth engagement under light torque loads and can also contribute to substantial spin losses. In contrast, dog clutches have near zero spin losses but cannot be used for power-on up-shifts due to lacking torque capacity prior to full engagement which yields an inability to absorb energy and synchronize speed before engagement. Accordingly, there is a need in the art for a torque transmitting assembly that combines the features of the plate clutch, e.g. able to provide power-on up-shifts, with the features of the dog clutch, e.g. minimized packaging, minimized spin loss, and robust torque capacity. 
     SUMMARY 
     A torque transmitting assembly is provided for selectively transmitting torque between a first member and a second member in a transmission of a motor vehicle. 
     In one embodiment, the torque transmitting device includes a plate clutch interconnected between the first member and the second member, the plate clutch having a maximum torque capacity limited to enabling full throttle single-transition up-shifts in the transmission when the plate clutch is fully engaged. A dog clutch is connected to the first member and selectively connected to the second member. The dog clutch is in frictional engagement with the plate clutch when the plate clutch is engaged, and the dog clutch is connected to the second member prior to the transmitted torque exceeding the maximum torque capacity of the plate clutch. 
     In another embodiment, a piston is hydraulically translatable to contact the plate clutch in order to engage the plate clutch and the dog clutch. 
     In yet another embodiment, the plate clutch includes a reaction disc slidably connected to a support and a friction disc slidably connected to the second member, wherein the support is supported by the piston and the dog clutch. 
     In yet another embodiment, the dog clutch is in frictional engagement with the friction disc when the piston contacts and translates the plate clutch. 
     In yet another embodiment, a biasing member contacts the dog clutch and is configured to bias the dog clutch to disengage with the second member and to disengage the plate clutch. 
     Further features, aspects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is an exemplary schematic of a powertrain in a motor vehicle; 
         FIG. 2  is a sectional view of a portion of a torque transmitting assembly in a first position and an exemplary transmission according to the principles of the present invention; 
         FIG. 3  is a sectional view of a portion of a torque transmitting assembly in a second position and an exemplary transmission according to the principles of the present invention; and 
         FIG. 4  is a sectional view of a portion of a torque transmitting assembly in a third position and an exemplary transmission according to the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     With reference to  FIG. 1 , an exemplary powertrain is generally indicated by reference number  10 . The powertrain includes an engine  12  connected to a transmission  14 . The engine  12  may be a conventional internal combustion engine or an electric engine, or any other type of prime mover, without departing from the scope of the present disclosure. In addition, additional components, such as hydrodynamic fluid driving devices such as torque converters and fluid couplings, may be disposed between the engine  12  and the transmission  14  without departing from the scope of the present disclosure. The engine  12  supplies a driving torque to the transmission  14 . 
     The transmission  14  includes a typically cast, metal housing  16  which encloses and protects the various components of the transmission  14 . The housing  16  includes a variety of apertures, passageways, shoulders and flanges which position and support these components. The transmission  14  includes a transmission input shaft  18 , a transmission output shaft  20 , and a gear and clutch arrangement  22 . It should be appreciated that while the transmission  14  is illustrated as a rear wheel drive transmission, the transmission  14  may have other configurations without departing from the scope of the present disclosure. The transmission input shaft  18  is connected with the engine  12  and receives input torque or power from the engine  12 . The transmission output shaft  20  is preferably connected with a final drive unit (not shown) which may include, for example, propshafts, differential assemblies, and drive axles. The transmission input shaft  18  is coupled to and provides drive torque to the gear and clutch arrangement  22 . 
     The gear and clutch arrangement  22  includes a plurality of gear sets and a plurality of shafts. The plurality of gear sets may include individual intermeshing gears, such as planetary gear sets, that are connected to or selectively connectable to the plurality of shafts. The plurality of shafts may include layshafts or countershafts, sleeve and center shafts, reverse or idle shafts, or combinations thereof. It should be appreciated that the specific arrangement and number of the gear sets and the specific arrangement and number of the shafts within the transmission  14  may vary without departing from the scope of the present disclosure. 
     The gear and clutch arrangement  22  further includes at least one torque transmitting assembly  30 . The torque transmitting mechanism  30  is selectively engageable to initiate at least one of a plurality of gear or speed ratios by selectively coupling individual gears within the plurality of gear sets to the plurality of shafts. The torque transmitting assembly  30  will be described in greater detail below. 
     The transmission  14  also includes a transmission control module  32 . The transmission control module  32  is preferably an electronic control device having a preprogrammed digital computer or processor, control logic, memory used to store data, and at least one I/O peripheral. The control logic includes a plurality of logic routines for monitoring, manipulating, and generating data. The transmission control module  32  controls the actuation of the torque transmitting assembly  30  via a hydraulic control system  34 . The hydraulic control system  34  is operable to selectively engage the torque transmitting assembly  30  by selectively communicating a hydraulic fluid to the torque transmitting assembly  30  that engages the torque transmitting device. The hydraulic fluid is communicated to the torque transmitting assembly  30  under pressure from a pump  36  that is driven by the engine  12  in the example provided. The pump  36  may be of various types, for example, a gear pump, a vane pump, a gerotor pump, or any other positive displacement pump. 
     With reference to  FIG. 2 , the torque transmitting assembly  30  according to the principles of the present invention is illustrated in operative association with a first component or member  40  and a second component or member  42  within the transmission  10 . The torque transmitting assembly  30  is operable to transmit torque between the first component  40  and the second component  42 . In the example provided, the first component  40  is a stationary housing and the second component  42  is a rotatable shaft or member. However, it should be appreciated that either of the components  40  and  42  may be, for example, a transmission case or housing, a gear, or any other component in a transmission. Accordingly, in the example provided, the torque transmitting assembly  30  is a brake, though it should be appreciated that the torque transmitting assembly  30  may be a clutch without departing from the scope of the present invention. 
     The torque transmitting assembly  30  generally includes a housing  44 , a hub  46 , and a torque transmitting device  48 . The clutch housing  44 , the hub  46 , and the torque transmitting device  48  are coaxial with one another and define an axis “X”. The hub  46  is rotatable about the axis “X”. 
     The torque transmitting device  48  is disposed within the clutch housing  44  and radially between the clutch housing  44  and the hub  46 . The torque transmitting device  48  includes a piston  50  disposed within an annular pocket  52  formed in an inside surface  54  of the clutch housing  44 . The piston  50  includes a radially extending disc portion  56 , an axially extending annulus  58 , and a radially extending apply member  60 . The disc portion  56 , the annulus  58 , and the apply member  60  are constructed as a unitary, solid piece in the example provided. The apply member  60  includes an apply face  62  that faces axially towards two clutch elements  64  and  66  which will be described in greater detail below. The apply face  62  is preferably annular and planar. Inner and outer seals  68  and  70 , respectively, seal the piston  50  to the annular pocket  52 . The piston  50  is hydraulically actuatable to slide or translate within the annular pocket  52  in a direction towards the clutch elements  64  and  66  to an engaged position and to slide or translate away from the clutch elements  64  and  66  to a disengaged position. 
     Coupled to the piston  50  is a support disc  72 . The support disc  72  extends substantially axially away from the piston  50  and supports the first element  64 , as will be described in greater detail below. The support disc  72  is discontinuous as further described below. 
     The first clutch element  64  includes a reaction plate  74  and a friction disc  76 . The reaction plate  74  is connected to and supported by the support disc  72 . For example, the reaction plate  74  includes a slot or aperture  78  that receives the support disc  72  therethrough. Therefore, the reaction plate  74  is rotationally fixed to the support disc  72 , the piston  50 , and the clutch housing  44  and is axially translatable along the axis “X” by the piston  50 . The friction plate  76  includes splines  80  meshed with a first set of grooves  82  formed on an outer surface of the hub  46 . Therefore, the friction plate  76  is rotationally fixed to the hub  46  but is axially translatable along the axis “X”. 
     The second clutch element  66  includes a dog clutch  84  disposed adjacent the friction disc  76 . The dog clutch  84  includes outer splines  86  meshed with grooves  88  formed and inner teeth  90  that are selectively engageable with a second set of grooves  92  formed on the outer surface of the hub  46 . Therefore, the dog clutch  84  is rotationally fixed to the clutch housing  44  but is axially translatable along the axis “X”. The dog clutch  84  further includes a compliment of openings or apertures  94  that receive portions of the support disc  72 . Portions of the support disc  72  extend through the openings  94  and are retained to the dog clutch  84  via a retaining device  96 . 
     The torque transmitting assembly  30  further includes a return spring  98  disposed adjacent the dog clutch  84 . The return spring  98  is fixed at an end thereof by a retainer ring  102  disposed within a groove  100  formed in the inner surface  54  of the clutch housing  44 . The return spring  98  is positioned to bias the dog clutch  84  axially away from the second set of grooves  92 . It should be appreciated that the return spring  98  may be retained in any number of different ways without departing from the scope of the present invention. 
     To engage the torque transmitting assembly  30 , the piston  50  is actuated by a flow of pressurized hydraulic fluid on an apply side of the piston  50 . The piston  50  translates in an axial direction towards the first clutch element  64  against the bias of the spring  98 . The apply face  62  of the piston  50  contacts the reaction plate  74  and moves the reaction plate  74  relative to the support disc  72  towards the friction plate  76 . In a first engaged position, shown in  FIG. 3 , the first clutch element  64  is engaged while the second clutch element  66  is not engaged. In this condition, torque is transferred through the clutch housing  44 , the spline  88 , spline  86  dog clutch  84 , friction disc  76  to hub  46 . During this state force is applied through the piston  50 , the reaction plate  74 , the friction disc  76 , the dog clutch  84 , the bias spring  98 , the retainer  102 , and into the clutch housing  44 . The first clutch element  64  is configured to have a torque capacity that allows power-on (full-throttle single-transition) up-shifts by the transmission  14 . This is accomplished by tuning the stiffness of bias spring  98  so that the force applied is high enough to allow the friction disc  76  to absorb energy but low enough to allow the bias spring  98  to prevent engagement of splines  90  and  92 . In addition, as the load through the first clutch element  64  increases as the piston  50  translates, the dog clutch  84  is rotationally synchronized with the friction disc  76  and therefore the hub  46 . 
     As the piston  50  continues to translate, and prior to the first clutch element  76  exceeding its maximum torque capacity, the dog clutch  84  engages the hub  46  via the second set of grooves  92 , as shown in  FIG. 4 . In this condition, the torque capacity of the torque transmitting assembly  30  is governed by the torque capacity of the dog clutch  84 . This device advantageously capitalizes on the ability modern powertrain control systems now have to allow for acute control of engine torque during shift events. This reduces the amount of shift energy which must be dissipated thereby requiring fewer clutch plates for thermal management. During clutch release events, the dog clutch  84  shall be released thereby allowing the friction disc  76  to provide a smooth release of torque capacity. 
     To disengage the torque transmitting assembly  30 , the apply side of the piston  50  is depressurized, and the return spring  98  moves the dog clutch  84 , and therefore the support disc  72  and piston  50  back to the unengaged position, thereby de-coupling the clutch housing  44  from the hub  46 . 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.