Patent Publication Number: US-2016223071-A1

Title: Transmission system for machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to transmission systems, and more specifically relates to a cooling system for a transmission system of a machine. 
     BACKGROUND 
     Stationary clutches are frequently employed in various machines to hold rotating components, such as a sun gear, a ring gear, or a planet carrier of a transmission system. The stationary clutches control torque or speed ratios received from the rotating components During operation of the stationary clutches, i.e., engagement and disengagement of the stationary clutches, heat is generated due to friction between contact surfaces. 
     Conventionally, in order to remove the heat generated, cooling oil is supplied to a contact surface of the stationary clutch through a number of holes. The holes are typically formed in a clutch hub. However, when the stationary clutch is engaged, i.e., when the clutch hub is stationary, cooling oil usually does not reach the contact surface. When the stationary clutch is disengaged, i.e., when the clutch hub rotates, then the cooling oil is again supplied through the holes to the contact surface. However, due to flow of the cooling oil through the holes in the clutch hub, a viscous drag is generated leading to parasitic losses in the transmission system. 
     U.S. Pat. No. 5,810,142, hereinafter referred to as &#39;142 patent, discloses a valve for flow control. The valve is provided with a flow recess and with a valve seat inside the flow recess. The valve seat is located beyond the axis of rotation of a rotating component and extends parallel to the axis of rotation. Inside the flow recess there is a movable valve body which interacts with the valve seat. A return spring takes effect on the valve body and the valve body is pressed in a closed position in the valve seat by the flow medium. However, the &#39;142 patent discloses use of the valve for controlling the flow of lubricant in the clutch housing. Further &#39;142 patent discloses use of pressurized fluid to actuate the valves. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect of the present disclosure, a transmission system of a machine is provided. The transmission system includes a housing member having an outer surface and an inner surface. The transmission system includes a clutch assembly disposed within the housing member. The clutch assembly includes at least one separator plate and at least one friction disc. The at least one separator plate is coupled with the inner surface of the housing member. The at least one friction disc is adapted to be engaged and disengaged with the at least one separator plate. The at least one friction disc is coupled with an engaging member of a gear set of the transmission system. The transmission system also includes a clutch cooling system. The clutch cooling system is associated with the housing member to selectively supply a fluid to the clutch assembly. The clutch cooling system includes a reservoir for storing the fluid. The clutch cooling system also includes a pump in fluid communication with the reservoir. Further, the clutch cooling system includes a fluid supply unit in fluid communication with the pump. The fluid supply unit is configured to supply the fluid from the reservoir to the clutch assembly. The clutch cooling system supplies the fluid at a plurality of locations around a circumference of the clutch assembly. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic side view of a machine having a transmission system with a clutch cooling system, according to one embodiment of the present disclosure: 
         FIG. 2  is a schematic view of the transmission system of  FIG. 1 , illustrating the clutch cooling system; 
         FIG. 3  is a sectional view of the transmission system with the clutch cooling system, taken along a line A-A′ of  FIG. 2 ; 
         FIG. 4  is a sectional view of the transmission system with a clutch cooling system, taken along a line A-A′ of  FIG. 2 , according to another embodiment of the present disclosure; and 
         FIG. 5  is a sectional view of the transmission system with a clutch cooling system, taken along a line A-A′ of  FIG. 2 , according to yet another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. 
       FIG. 1  is a schematic view of a machine  10  having a transmission system  12  having a clutch cooling system  14 , according to one embodiment of the present disclosure. The machine  10  may be an earth moving machine that may include, but is not limited to, a backhoe, an excavator, a tractor, a loader, a motor grader, or any other earth moving machine. In the present example, the machine  10  is embodied as a wheel loader. 
     The machine  10  includes a frame  16 , an operator cabin  18  for accommodating an operator, an implement system  20  coupled to the frame  16 , a pair of ground engaging members  22  for propelling the machine  10 , a compartment  24  for accommodating a power source  26 , the transmission system  12  drivably coupled to the power source  26 , and the clutch cooling system  14 . 
     The operator cabin  18  is supported on the frame  16  of the machine  10 . The operator cabin  18  includes a number of input devices (not shown) for controlling of the machine  10 . The input devices (not shown) may include, but are not limited to, a push-button, a control lever, and a steering wheel. The input devices are provided to control a movement of the implement system  20  to different positions, in order to perform various operations such as, a loading operation, a dumping operation, an excavating operation, or any other earthmoving operation known in the art. 
     The implement system  20  is disposed at a front end  28  of the machine  10 . The implement system  20  includes a bucket  30  pivotally coupled to a linkage member  32 . The linkage member  32  is connected to the frame  16  of the machine  10 . In other examples, the implement system  20  may include, but is not limited to, an auger, a blade, a fork, a hammer, and a ripper. 
     The power source  26  is accommodated in the compartment  24  at a rear end  38  of the machine  10 , The power source  26  includes an internal combustion engine. The internal combustion engine may be a diesel engine, a gasoline engine, a gaseous fuel-powered engine, a turbine engine, or any other type of combustion engine known in the art. In other examples, the power source  26  may be anon-combustion source of power, such as a fuel cell or a battery. The power source  26  is provided for generating power to propel the machine  10  and to operate the implement system  20  of the machine  10 . The power source  26  is connected to the transmission system  12 . More specifically, the power source  26  is connected to the transmission system  12  through an input member  40 . In one example, the power source  26  may be connected to a torque convertor (not shown) that is further connected to the transmission system  12  through the input member  40 . 
       FIG. 2  illustrates a schematic view of the transmission system  12  with the clutch cooling system  14 . Referring to  FIG. 1  and  FIG. 2 , the transmission system  12  is connected to the pair of ground engaging members  22 . More specifically, the transmission system  12  is connected to the pair of ground engaging members  22  through an output member  42 . The transmission system  12  supplies power received from the power source  26  to the pair of ground engaging members  22  through the output member  42 . 
     The transmission system  12  is embodied as a multi-speed transmission system. The transmission system  12  includes a housing member  44  having an outer surface  46  and an inner surface  48 . The housing member  44  is rigidly attached to the frame  16  of the machine  10 . The housing member  44  includes a plurality of holes  50  extending from the outer surface  46  to the inner surface  48 . As illustrated, the holes  50  are circumferentially distributed in the housing member  44 . The holes  50  are in fluid communication with the clutch cooling system  14 . 
     The transmission system  12  includes a number of gear sets  52 ,  54 ,  56 ,  58 . Each of the gear sets  52 ,  54 ,  56 ,  58  is rotatably supported within the housing member  44 . The gear sets  52 ,  54 ,  56 ,  58  are aligned about a rotational axis X-X′ of the output member  42 . Each of the gear sets  52 ,  54 ,  56 ,  58  is drivably coupled to each other, for transmitting the output power from the power source  26  to the pair of ground engaging members  22  through the output member  42 . Further, the gear sets  52 ,  54 ,  56 ,  58  are drivably coupled to the input member  40  and the output member  42 . The gear sets  52 ,  54 ,  56 ,  58  are provided to control a power output received by the pair of ground engaging members  22  at the output member  42  from the power source  26 . 
     Each of the gear sets  52 ,  54 ,  56 ,  58  includes a number of engaging members. The number of engaging members includes a sun gear  60 , a planetary carrier  62 , and a ring gear  64 . The sun gear  60  rotates about the rotational axis X-X′ of the output member  42 . The planetary carrier  62  is provided to support a number of planet gears  66  (shown in  FIG. 3 ). The planet gears  66  are circumferential spaced about the sun gear  60 . The planet gears  66  mesh with the sun gear  60  and the ring gear  64 . In one example, the sun gear  60 , the planetary carrier  62 , the ring gear  64 , and the planet gears  66  may be rotated as a single unit. In another example, alternatively, the planetary carrier  62 , and the ring gear  64  may be held stationary. 
     Further, the transmission system  1  includes a number of control elements  68  disposed within the housing member  44 . The control elements  68  are operatively coupled to the gear sets  52 ,  54 ,  56 ,  58 . The control elements  68  are provided to control the power output received by the pair of ground engaging members  22  at the output member  42 . More specifically, the control elements  68  are selectively engaged with the gear sets  52 ,  54 ,  56 ,  58  to obtain, for example, a set of ten forward gear ratios and one reverse gear ratio between the input member  40  and the output member  42 . In one example, the control elements  68  may also include, but are not limited to, synchronizers, brakes, or a combination thereof. 
     The control elements  68  are hydraulically operated to control the power output at the output member  42 . In one example, the control elements  68  may be electronically operated to control the power output at the output member  42 . The control elements  68  include a number of rotational clutches  70 ,  72 ,  74  and a number of clutch assemblies  76 ,  78 ,  80 . The rotational clutches  70 ,  72 ,  74  are disposed within the housing member  44  of the transmission system  12 . 
       FIG. 3  is a sectional view of the transmission system  12  with the clutch cooling system  14 , taken along a line A-A′ of  FIG. 2 . Referring to  FIG. 2  and  FIG. 3 , each of the clutch assemblies  76 ,  78 ,  80  is provided to selectively hold the sun gear  60 , the planetary carrier  62 , and the ring gear  64  stationary, thereby controlling the power output at the output member  42 . More specifically, the clutch assemblies  76 ,  78 ,  80  control a rotational speed of the output member  42  with respect to the input member  40  by obtaining different gear ratios between the gear sets  52 ,  54 ,  56 ,  58 . Each of the clutch assemblies  76 ,  78 ,  80  includes a number of separator plates  82  and a number of friction discs  84 . It should be noted that although the present disclosure is described with regard to the clutch assembly  76 , the description is applicable to the clutch assemblies  78 ,  80  as well, without departing from the scope of the present disclosure. 
     The separator plates  82  of the clutch assembly  76  are coupled with the inner surface  48  of the housing member  44 . Each of the separator plates  82  includes a number of engaging portions  86  disposed circumferentially on the separator plates  82 . The engaging portions  86  are coupled to the inner surface  48  of the housing member  44 . More specifically, the engaging portions  86  are coupled to a number of rods  87  that are connected to the inner surface  48  of the housing member  44 . In one example, the engaging portions  86  are coupled to spline teeth (not shown) formed on the inner surface  48  of the housing member  44 . 
     The friction discs  84  are adapted to be engaged with the separator plates  82 . Each of the friction discs  84  and the separator plates  82  are alternatively stacked on each other in the housing member  44  to form a clutch pack. More specifically, the friction discs  84  and the separator plates  82  are interleaved. The friction discs  84  are coupled with one of the engaging members of the gear set  56  of the transmission system  12 . More specifically, each of the friction discs  84  is coupled with the ring gear  64  of the gear set  56 . The friction discs  84  are adapted to rotate along with the ring gear  64  of the gear set  56 , when the clutch assembly  76  is in a disengaged condition. In the disengaged condition, the friction discs  84  disengages with the separator plates  82  of the clutch assembly  76 . When the clutch assembly  76  is in an engaged condition, the friction discs  84  engages with the separator plates  82 , thereby locking the friction discs  84  to the housing member  44  along with the ring gear  64 . 
     During the engaged condition of the clutch assembly  76 , the separator plates  82  engage with the friction discs  84  to hold the ring gear  64  stationary with respect to the housing member  44  of the transmission system  12 . In one example, the clutch assembly  76  may include an actuating mechanism, (not shown) such as a piston assembly for engaging the friction discs  84  with the separator plates  82 . Due to engagement of the friction discs  84  with the separator plates  82 , friction energy is generated between contact surfaces (not shown) of the separator plates  82  and the friction discs  84 . The term “contact surfaces” herein refers to surfaces of the separator plates  82  and the friction discs  84  which come in contact with each other during the engaged condition of the clutch assembly  76 . During the disengaged condition of the clutch assembly  76 , the friction discs  84  rotate freely along with the ring gear  64  of the gear set  56 . 
     The clutch cooling system  14  is provided in the transmission system  12  to supply a fluid to the contact surfaces of the separator plates  82  and the friction discs  84 . The clutch cooling system  14  is associated with the housing member  44  to selectively supply the fluid to the clutch assembly  76 . Specifically, the clutch cooling system  14  is associated with the housing member  44  to selectively supply the fluid to the clutch assembly  76  through the holes  50  of the housing member  44 . The clutch cooling system  14  supplies the fluid at a plurality of locations around a circumference of the clutch assembly  76  through the plurality of holes  50 . More specifically, the clutch cooling system  14  supplies the fluid at the plurality of locations around the circumference of the clutch assembly  76 , while the friction discs  84  is engaged with the separator plates  82  of the clutch assembly  76 . In an example, the clutch cooling system  14  supplies the fluid at the plurality of locations around the circumference of the clutch assembly  76 , while the friction discs  84  is disengaged with the separator plates  82  of the clutch assembly  76 . As shown in  FIGS. 2 and 3 , the clutch cooling system  14  includes a reservoir  88 , a pump  90 , and a fluid supply unit  92 . In one example, the reservoir  88  may be a tank for storing the fluid at a predefined pressure. In another example, the reservoir  88  may be an oil pan (not shown) provided within the transmission system  12  of the machine  10 . The fluid may include, but is not limited to, engine cooling oil, transmission cooling oil, or any other fluid known in the art. 
     The pump  90  is in fluid communication with the reservoir  88 . The pump  90  draws the fluid from the reservoir  88  to the housing member  44  of the transmission system  12 . More specifically, the pump  90  draws the fluid from the reservoir  88  to the holes  50  formed on the housing member  44  of the transmission system  12 . The pump  90  includes an inlet  94  and an outlet  96 . The inlet  94  is connected to the reservoir  88  through a fluid duct  98  for receiving the fluid from the reservoir  88 . The outlet  96  is connected to the fluid supply unit  92  for supplying the fluid to the fluid supply unit  92 . The pump  90  is drivably connected to the power source  26  of the machine  10 . 
     The fluid supply unit  92  is in fluid communication with the pump  90  and the holes  50  of the housing member  44  of the transmission system  12 . The fluid supply unit  92  receives the fluid from the reservoir  88  through the pump  90 . The fluid supply unit  92  supplies the fluid from the reservoir  88  to the clutch assembly  76 . More specifically, the fluid supply unit  92  supplies the fluid to the clutch assembly  76  through the holes  50  of the housing member  44 . The fluid supply unit  92  controls a flow of the fluid from the reservoir  88  to the clutch assembly  76  through the holes  50  of the transmission system  12 . 
     The fluid supply unit  92  includes a flow control unit  100  and a number of fluid conduits  102 . The flow control unit  100  includes an inlet port  104  and an outlet port  106 . The inlet port  104  is connected to the outlet  96  of the pump  90  through a fluid duct  99  for receiving the fluid from the pump  90 . The outlet port  106  is connected to the holes  50  of the housing member  44  through the fluid conduits  102  for supplying the fluid to the holes  50 . More specifically, the outlet port  106  is connected to each of the holes  50  of the housing member  44  through the fluid conduits  102 . Further, the holes  50  of the housing member  44  dispense the fluid received from the outlet port  106  on each of the separator plates  82  and the friction discs  84  of the clutch assembly  76 . The flow control unit  100  may include, but is not limited to, a solenoid valve, a pilot actuated valve, and a spool valve. 
     In one example, the flow control unit  100  may be the solenoid valve actuated by an electric current supplied to the solenoid valve. In another example, the flow control unit  100  may be the pilot actuated valve operated by a clutch pressure. In the present example, the pilot actuated valve is operated to an open position and a closed positon, based on the clutch pressure detected during the engaged condition of the clutch assembly  76 . In yet another example, the flow control unit  100  may be embodied as the spool valve mechanically operated by the actuating mechanism, such as the piston. In the present example, the spool valve is switched to an open position and a closed position, based on the movement of the piston during the engaged condition of the clutch assembly  76 . In one example, the flow control unit  100  may supply the fluid to the holes  50  of the housing member  44  in the engaged condition and the disengaged condition of the clutch assembly  76 . In one example, the clutch cooling system  114  supplies the fluid continuously from the reservoir  88  to the clutch assembly  76  through the holes  50  of the housing member  44 , in the engaged condition and the disengaged condition of the clutch assembly  76 . In the present example, the flow control unit  100  is redundant in the fluid supply unit  92  of the clutch cooling system  114 . 
       FIG. 4  is a sectional view of the transmission system  12  with a clutch cooling system  114 , taken along a line A-A′ of  FIG. 2 , according to another embodiment of the present disclosure. Similar to the clutch cooling system  14  of the transmission system  12  in  FIG. 3 , the clutch cooling system  114  of  FIG. 4  includes a reservoir, such as the reservoir  88 , a pump, such as the pump  90 , and a fluid supply unit  115 . 
     The fluid supply unit  115  includes a fluid conduit  116  and a flow control unit, such as the flow control unit  100 . The fluid supply unit  115  is in fluid communication with the pump  90  and a housing member  45  of the transmission system  12 . The flow control unit  100  includes an inlet port, such as the inlet port  104  and an outlet port, such as the outlet port  106 . As explained earlier, the inlet port  104  is connected to the outlet  96  of the pump  90 . 
     The fluid supply unit  115  also includes a cylindrical tube  121 . The cylindrical tube  121  is positioned on an outer surface  47  of the housing member  45 . The cylindrical tube  121  is connected to the outlet port  106  of the flow control unit  100  through the fluid conduit  116 . The cylindrical tube  121  is in fluid communication with the flow control unit  100  through the fluid conduit  116  for receiving the fluid from the reservoir  88 . The cylindrical tube  121  includes a number of orifices  122  circumferentially spaced apart on the cylindrical tube  121 . The orifices  122  spray the fluid on the clutch assembly  76  through a number of openings  123  circumferentially distributed in the housing member  45 . More specifically, the orifices  122  dispense the fluid received from the reservoir  88  on each of the separator plates  82  and the friction discs  84  of the clutch assembly  76  through the openings  123  of the housing member  45 . 
       FIG. 5  is a sectional view of the transmission system  12  with a clutch cooling system  124 , taken along a line A-A′ of  FIG. 2 , according to yet another embodiment of the present disclosure. Similar to the clutch cooling system  14  of the transmission system  12  in  FIG. 3 , the clutch cooling system  124  of  FIG. 5  includes a reservoir, such as the reservoir  88 , a pump, such as the pump  90 , and a fluid supply unit  130 . The pump  90  includes an inlet, such as the inlet  94  and an outlet, such as the outlet  96 . As explained earlier, the inlet  94  is connected to the reservoir  88  and the outlet  96  is connected to the fluid supply unit  130 . 
     The fluid supply unit  130  includes a number of fluid conduits  132  and a flow control unit, such as the flow control unit  100 . The fluid supply unit  130  is in fluid communication with the pump  90  and a housing member  134 . The flow control unit  100  includes an inlet port, such as the inlet port  104  and an outlet port, such as the outlet port  106 . The inlet port  104  is connected to the outlet  96  of the pump  90 . 
     The fluid supply unit  130  also includes a number of spraying units  137 . The spraying units  137  are positioned in a number of openings  142  circumferentially distributed in the housing member  134 . Each of the spraying units  137  includes an inlet  138  and an outlet  140 . The inlet  138  is connected to the flow control unit  100  through the fluid conduits  132  for receiving the fluid from the reservoir  88 . More specifically, the inlet  138  is connected to the outlet port  106  of the flow control unit  100  through the fluid conduits  132 . The outlet  140  dispenses the fluid received from the reservoir  88  on each of the separator plates  82  and the friction discs  84  of the clutch assembly  76 . 
     INDUSTRIAL APPLICABILITY 
     The present disclosure relates to the clutch cooling systems  14 ,  114 ,  124  for the transmission system  12  of the machine  10 . The clutch cooling systems  14 ,  114 ,  124  selectively supply the fluid to the clutch assembly  76  for cooling of the clutch assembly  76 . The holes  50  formed on the housing member  44  enable supply of the fluid to the clutch assembly  76 . A number of holes  50  can be varied to achieve a desired amount of flow of fluid for cooling of the clutch assembly  76 . The clutch cooling system  14  includes the fluid supply unit  92  that supplies the fluid to the clutch assembly  76  during the engaged condition and the disengaged condition of the clutch assembly  76 . Therefore, the clutch cooling system  14  can reduce temperature of the clutch assembly  76  when the clutch assembly  76  is in the engaged condition as well as when the clutch assembly  76  is in the disengaged condition. 
     The fluid supply unit  92  supplies the fluid from the reservoir  88  to the clutch assembly  76  in the transmission system  12  through the holes  50 . The holes  50  supply the fluid to the clutch assembly  76  and are provided on the housing member  44 . Therefore, the fluid supplied to the clutch assembly  76  flows from the outer surface  46  of the housing member  44  to the inner surface  48  of the housing member  44 . As a result, drag losses arising from fluid flowing through a clutch hub are reduced. Accordingly, parasitic losses in the transmission system  12  are also reduced. by the clutch cooling systems  14 ,  114 ,  124  of the present disclosure. Further, the spraying units  137  of the clutch cooling system  124  can be used for cooling the clutch assembly  76 , when the clutch assembly  76  is located within the housing member  134  at a larger distance from the inner surface  48  of the housing member  134 . 
     The clutch cooling system  14  of the present disclosure facilitates supply of the fluid, through the holes  50  on the housing member  44 , directly to the clutch assembly  76 . Therefore, the clutch cooling system  14  increases a cooling rate of the clutch assembly  76  when the clutch is engaged. The clutch cooling system  14  can be employed along with another conventional cooling system to further increase the cooling rate of the clutch assembly  76 . Further, the clutch cooling system  14  can be conveniently retrofittable with a variety of other transmission systems. 
     The clutch cooling system  14  can be used in various types of transmission systems, such as a semi-automatic transmission and an automatic transmission. Further, the clutch cooling system  14  can be employed in the transmission system  12  of any type of machine used in construction applications, transportation applications, power generation applications, aerospace applications, locomotive applications, marine applications, and other engine power applications. Therefore, the clutch cooling system  14  has a wide range of application across industries. Therefore, the present disclosure offers the transmission system  12  with the clutch cooling system  14  that is economical and cost effective. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.