Abstract:
A pump comprising a housing having a first cavity and a second cavity, where the first cavity has a first motor and a pump element located therein. The first cavity is also connected to an external gear connected to the outside of the housing for receiving rotation power from a vehicle engine. The second cavity has a second motor that selectively connects to the pump element in the first cavity to provide toque.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/692,070, filed Aug. 22, 2012. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present disclosure relates generally to an improved pump, and more particularly, to an improved hybrid variable external gear pump for use in a transmission for a vehicle such as an automobile, truck, van, utility, industrial equipment, fleet, cargo or the like. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many transmissions, engines, transfer cases and other power transferring devices are equipped with oil pumps for lubrication or other pressurized fluid supply. Internal oil pumps are typically continuously driven. While known arrangements are fairly simple to construct, continuously, mechanically driving the pump may not be the most efficient way of operating the vehicle, let alone even possible in some electric vehicle applications. During certain modes of vehicle operation, the input shaft driving the pump may rotate at relatively high speed thereby producing relatively high fluid flow at a time when relatively low or no fluid flow is required. The energy to drive the pump during these modes of operation is not providing value and may be considered inefficient waste. 
         [0004]    It is generally known to have a variable displacement vane pump for use in a transmission in a vehicle. One particular example is disclosed in U.S. Pat. No. 4,342,545, to Schuster, the entire contents of which are incorporated herein by reference thereto. Variable displacement pumps are generally known in transmission control systems, however, these prior art devices have generally been of the gerotor or sliding ring type in which the control thereof is maintained by a spring. It is also generally known in electric vehicle applications to provide two pumps—a mechanical pump driven by a power take off from the engine and an electric motor-driven pump for use when the engine is not running. This adds significant expense and complexity as well additional potential failure modes and control issues. There is also known an externally mounted electric fluid pump for pumping fluid within a power transmission device as disclosed in US Patent Application Publication Number 2010/0290934A1, the entire contents of which are incorporated herein by reference thereto. 
         [0005]    Despite the long known solutions, there remains a significant need to provide an improved variable displacement vane pump capable of providing improved performance and gains in efficiency and packaging of the pump. In spite of the long known solutions, there remains a significant need to provide an improved variable displacement pump that can overcome the problems of the known art. 
       SUMMARY OF THE INVENTION 
       [0006]    A pump comprising a housing having a first cavity and a second cavity. A primary shaft extending through the first cavity having a first end and a second end with a first motor in the cavity coupled to a second end of the primary shaft. A drive gear coupled to the first end of the primary shaft by a one way clutch coupling the drive gear and the primary shaft such that the drive gear can rotate the primary shaft in a first direction. The first motor is coupled to the second end of the drive shaft and can rotate the drive shaft in an opposite direction. The one way clutch prevents such rotation from being transferred to the drive gear. 
         [0007]    A second shaft extends through the second cavity and is connected to a second motor located in the second cavity. The second shaft has a first end rotatably supported in the housing and a second end coupled to the second motor. The second cavity also has a first failsafe spring located proximal to the first end of the second shaft and a second failsafe spring located proximal to the second end of the step motor shaft. A first seal and a second seal with a second shaft positioned gear between the seals, are coupled to the step motor shaft for contacting and providing torque to a pump element in the first cavity. 
         [0008]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a perspective view of an exemplary embodiment of an outer rotor drive and pump according to the present disclosure; 
           [0011]      FIG. 2  is an alternate perspective view of the outer rotor drive and pump of  FIG. 1 ; 
           [0012]      FIG. 3  is a further alternate perspective view of the outer rotor drive of  FIG. 1 ; 
           [0013]      FIG. 4  is a partial, perspective view of the exemplary embodiment of the outer rotor drive and pump of  FIG. 1  according to the present disclosure; 
           [0014]      FIG. 5  is an exploded perspective view of the exemplary embodiment of the outer rotor drive and pump of  FIG. 1  according to the present disclosure; 
           [0015]      FIG. 6  is an alternate exploded perspective view of the exemplary embodiment of the oil pump of  FIG. 1  according to the present disclosure; 
           [0016]      FIG. 7  is a perspective view of the second shaft gear of the second motor of pump of  FIG. 6  according to the present disclosure; and 
           [0017]      FIG. 8  is an exploded perspective view of the second gear of the second motor of pump of  FIG. 7  according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0019]    Referring in general to all of the Figures, the present disclosure and teachings described herein provide for an oil pump  10  and oil pump operating system for use with a cooling system in a transmission or engine. The oil pump  10  is design so it can be driven using multiple sources. The oil pump  10  includes a housing  11  having a pump portion  12  and a motor portion  14  that is coupled to the pump portion  12  at one end  16  of the pump portion  12 . The interiors of the pump and motor portions have a first cavity  18  and second cavity  19 , which are both generally cylindrically shaped and aligned side-by-side as shown in the Figures. The first cavity  18  is connected to an inlet  13  and outlet  15  disposed through the housing  11 . Fluid such as oil or transmission fluid enters the housing  11  through the inlet  13  and exits an outlet  15 . The movement of fluid through the housing  11  is caused by a pump element  31  positioned in the first cavity  18 . The pump element  31  in the present embodiment of the invention is a gerotor formed on the primary shaft  30 . 
         [0020]    The motor portion  14  is closed at an opposite end using a housing cover  20 . The motor portion  14  includes a first motor  22  in the first cavity  18  and a second motor  24 , (a generally smaller, step motor), located in the second cavity  19 . The first motor  22  and second motor  24  are coupled to a controller  26  located between the first motor  22  and second motor  24  and the end of the motor portion and the housing cover  20 . 
         [0021]    In one exemplary embodiment as shown in the Figures, the oil pump  10  of the present disclosure preferably includes only a single controller  26  for controlling both the first motor  22  and second motor  24 , the controller  26  being located at an end of the motor portion  14 . In the exemplary embodiment shown in the Figures, locating the controller  26  at the one end of the motor portion  14  of the oil pump  10  and co-locating the motors as disclosed allows for one controller to manage the two motors to thereby provide a lower cost controller and lower cost oil pump. In one alternate embodiment, it is contemplated that two controllers are used wherein each controller controls a single motor. In a further alternative embodiment, it is contemplated that two controllers are used wherein each controller controls a single motor and includes a backup controller for the other motor to provide redundancy. 
         [0022]    In one exemplary aspect, the oil pump  10  is driven using power take off from the engine using an external gear  28  coupled to the power take off. The external gear  28  is coupled to the power take off from one of the engine or the transmission and is driven thereby to cause rotation of the oil pump  10 . The external gear  28  is coupled to a primary shaft  30  located in the first cavity  18  in pump portion  12  of the pump  10  using a fastener  32 , such as the screw shown in the Figures, or other known and appropriate coupling device. 
         [0023]    The external gear  28  of the pump  10  includes a one way clutch  34 . The one way clutch  34  is configured so that rotation of the external gear  28  in one direction will be transferred directly to the primary shaft  30 , and causes it to rotate directly with the external gear  28 . The pump element  31  is connected to the primary shaft  30  and rotates in response to torque inputted from the external gear  28  or torque inputted from the first motor  22  or the second motor  24 . Rotation of the external gear  28  in the opposite direction does not cause rotation of the primary shaft  30 . More significantly, rotation of the primary shaft  30  does not cause rotation of the external gear  28  because the one way clutch mechanism is designed to only allow forces to be transferred from the external gear  28  to the primary shaft  30  and not from the primary shaft  30  to the external gear  28 . 
         [0024]    Accordingly, in one mode of operation of the oil pump  10 , such as when the engine is operating in a start/stop mode, (also known as a start and go mode or application), the engine is stopped when the vehicle is stopped and there is no demand from the operator for the vehicle engine to run. When the engine is stopped, the engine and transmission do not rotate and there is no operating power take off from the engine or transmission that can cause the external gear  28  to rotate. Therefore the oil pump  10  cannot be driven by the external gear  28 . In this mode, the oil pump  10  is operated by the first motor  22 , which is a brushless direct current (“BLDC”) motor using power, such as electricity, to cause the first motor  22  to rotate and thereby rotate the primary shaft  30  and pump element  31 . In this mode, the one way clutch prevents rotation of the shaft from being transferred to the external gear  28  and back into the power take off mechanism and/or the engine and transmission. The BLDC motor can be of any known or appropriate type and preferably has a power rating of between about 50W and 80W, sufficient to drive the pump  10  in the start and go mode or application. 
         [0025]    As shown in the Figures, the second motor  24 , of the oil pump  10  and its control, is a step motor located in the end near the first motor  22  and in the second cavity  19  of the motor portion  14  aligned with the pump portion. The second motor  24  is coupled to a second shaft  36 . The second shaft  36  includes a bearing  38  for supporting rotation of the second shaft  36  within the second cavity  19 . The second shaft  36  has a second shaft gear  37  that engages with the pump element  31  in order to apply torque from the second motor  24  to the pump element  31  through the second shaft gear  37 . The second shaft gear  37  has seals  39 ,  39 ′ on either side that prevent fluid from leaking from the first cavity  18  to the second cavity  19 . The seals  39 ,  39 ′ are optional and it is within the scope of the invention for some embodiments to allow fluid to flow into the second cavity  19 . The second motor  24  is preferably a three phase stepper motor (having an operating range of approximately 3W-4W that operates to change the displacement of the pump and to the force balance of the second shaft  36  with bearing  38 . The use of the second motor  24  changes the displacement of the pump and thereby reduces the torque for operating the pump at the cold start. In one embodiment, the second motor  24  preferably includes an over molded motor winding with an integrated bus bar and also includes smart control implemented in the controller  26  to keep high accuracy of control and high dynamic regulation function. 
         [0026]    In one exemplary embodiment as shown in the Figures, the oil pump  10  further include an oil flow for cooling portions of the controller  26 , or MOSFETS of the step motor and/or the BLDC motor. In one alternate exemplary embodiment, it is contemplated that the arrangement of the controller  26  and the motors  22 ,  24  of the oil pump  10  of the present disclosure further includes a robust, low-cost Bx_By flux position sensor integrated in PCB of the controller  26 . With the arrangement of the oil pump  10  and motors  22 ,  24  of the present disclosure, the first motor  22  and controller  26  may be used to generate regeneration energy during operation of the oil pump  10  when the engine reduces speed, such as when the vehicle is slowing down and there is a lower demand for oil pumping within the transmission and engine and the transmission continues to rotate and drive the external gear  28  of the oil pump  10  and the motors  22 ,  24  can be used to generate electricity that can be stored for later use. In one exemplary embodiment, upon operation of the second motor  24 , failsafe spring(s)  40 ,  40 ′ move the second shaft gear  37  coupled to the second shaft  36  to a full displacement position if there is issue in the electrical controller  26 . The conversion of rotational movement of the second motor  24  to linear movement of the second shaft gear  37  is accomplished using a lead screw  42  or mated threads formed between a gear support  41  and the surface of the second shaft  36 .  FIG. 8  shows how the second shaft gear  37  is press fit onto the gear support, that is connected to one of the seals  39 ′. The gear support  41  is used to connect the seals  39 ,  39 ′ and second shaft gear  37  onto the second shaft  36 . 
         [0027]    The oil pump, its motors and the controller can be operated using any known or appropriate communications protocol including, but not limited to, CAN or LIN communication protocols. 
         [0028]    The description of the invention is merely exemplary in nature and, thus, 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.