Abstract:
An integrated motor and drive assembly includes a motor, a fan, and a drive unit. The motor is responsive to at least one drive signal. The fan is axially aligned with the motor and operable to generate a cooling flow. The drive unit is axially aligned with the fan and operable to generate the drive signal. The cooling flow traverses the motor and the drive unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     The present invention relates generally to the art of integrated motor and drive systems and, more particularly, to a motor with an integrated drive unit and a shared cooling fan.  
         [0004]     This section of this document is intended to introduce various aspects of art that may be related to various aspects of the present invention described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the present invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.  
         [0005]     Motors have broad application in industry, particularly when large horsepower is needed. Typically, power in the form of AC current provided by a utility is not suitable for end use in consuming facilities. Thus, prior to end use, power delivered by a utility is converted to a useable form. To this end, a typical power “conditioning” configuration includes an AC-to-DC rectifier that converts the utility AC power to DC across positive and negative DC buses (i.e., across a DC link) and an inverter linked to the DC link that converts the DC power back to three phase AC power having an end-useable form (e.g., three phase, relatively high frequency AC voltage). A controller controls the inverter in a manner calculated to provide voltage waveforms required by the consuming facility. The inverter includes a plurality of switches that can be controlled to link and delink the positive and negative DC buses to motor supply lines. The linking-delinking sequence causes voltage pulses on the motor supply lines that together define alternating voltage waveforms. When controlled correctly, the waveforms cooperate to generate a rotating magnetic field inside the motor stator core. In an induction motor, the magnetic field induces a field in motor rotor windings. The rotor field is attracted to the rotating stator field and thus the rotor rotates within the stator core. In a permanent magnet motor, one or more magnets on the rotor are attracted to the rotating magnetic field. The rectifier, inverter, and control circuitry are commonly referred to as a motor drive unit.  
         [0006]     The use of integrated units where the motor drive is integrated with the motor to create an “integrated motor and drive system” has become more widely used. One advantage of such systems is their compactness and ease of installation into a larger industrial or other application, due largely to the close proximity of the drive to the motor. Generally, the drive is disposed on the motor or arranged in an integral housing with the motor.  
         [0007]     One issue arising from the integrated motor and drive system arrangement involves providing adequate cooling flow to dissipate the collective heat generated by the motor and drive. Previous techniques for providing cooling for an integrated motor and drive involve providing independent cooling for the motor drive or diverting a portion of the cooling flow from the motor fan to impinge upon the motor drive or a heat sink associated with the motor drive. These solutions add cost to the motor drive assembly and sometimes fail to provide adequate cooling, as only a portion of the cooling flow is employed.  
         [0008]     Another disadvantage is that heat sinks applied to motor drive components typically provide a cooling effect that is substantially uniform over its surface area. This is due to the even, or regular, distribution of the heat transfer fins on the face of the heat sink. This design limitation largely ignores the reality in motor drives that certain power and other electronic components generate large amounts of heat, while other devices may generate only small amounts. Thus, a traditional heat sink requires that either the power components be evenly distributed over the heat sink surface with regard to their power generating capabilities, or that a large enough heat sink is used to compensate for “hot spots” created by the physical arrangement of power components to provide for adequate cooling of the largest expected localized areas of heat generation.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     The present inventors have recognized that a motor and drive assembly may be implemented where a motor is axially aligned with a motor drive unit to allow cooling flow generated by a fan associated with the motor to cool both the motor and the motor drive unit.  
         [0010]     One aspect of the present invention is seen in an assembly including a motor, a fan, and a drive unit. The motor is responsive to at least one drive signal. The fan is axially aligned with the motor and operable to generate a cooling flow. The drive unit is axially aligned with the fan and operable to generate the drive signal. The cooling flow traverses the motor and the drive unit.  
         [0011]     Another aspect of the present invention is seen in an assembly including a motor, a fan, a fan shroud, a drive unit, and a drive enclosure. The motor is responsive to at least one drive signal. The fan is axially aligned with the motor and operable to generate a cooling flow. At least a portion of the cooling flow traverses the motor. The fan shroud is mounted to the motor and defines a fan cavity enclosing at least a portion of the fan and at least one opening communicating with the fan cavity. The drive unit is disposed within the cooling flow and operable to generate the drive signal. The drive enclosure is mounted to the fan shroud and defines a drive cavity enclosing at least a portion of the drive unit and at least one vent communicating with the drive cavity.  
         [0012]     Yet another aspect of the present invention is seen in an assembly including a motor, a fan, and a drive unit. The motor is responsive to at least one drive signal. The fan is operable to generate a cooling flow including an intake component and an exhaust component. The drive unit is operable to generate the drive signal. One of the intake component and the exhaust component traverses the drive unit and the other of the intake component and the exhaust component traverses the motor.  
         [0013]     These and other objects, advantages and aspects of the invention will become apparent from the following description. The particular objects and advantages described herein may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made, therefore, to the claims herein for interpreting the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0014]     The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:  
         [0015]      FIG. 1  is an exploded isometric view of an integrated motor and drive assembly in accordance with one embodiment of the present invention;  
         [0016]      FIG. 2  is an exploded side view of the motor and drive assembly of  FIG. 1 ; and  
         [0017]      FIG. 3  is a side cutaway view of the motor and drive assembly of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]     One or more specific embodiments of the present invention will be described below. It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. Nothing in this application is considered critical or essential to the present invention unless explicitly indicated as being “critical” or “essential.” 
         [0019]     Referring now to the drawings wherein like reference numbers correspond to similar components throughout the several views and, specifically, referring to  FIGS. 1, 2  and  3 , the present invention shall be described in the context of a motor and drive assembly  10 . The motor and drive assembly  10  includes an electric motor  20 , fan shroud  30 , mounting bracket  40 , drive unit  50 , and drive enclosure  60 . As shown in  FIG. 3 , the electric motor  20  has a generally cylindrical housing  70  surrounding a motor core  80 . The motor core  80  converts electrical energy to mechanical energy to drive external devices coupled to the motor  20 . The motor core  80  includes a stator  90 , a rotor  100 , and any other wiring and circuitry (not shown) for driving the motor  20 . The rotor  100  is coupled to a shaft  110  extending through a central longitudinal axis of the motor  20 .  
         [0020]     During operation of the motor  20 , electrical current is provided to the windings of the stator  90  by the drive unit  50 , which generates a magnetic field that induces a current in the windings of the rotor  100 . The induced current in the windings of the rotor  100  also generates a magnetic field in an opposite direction with respect to the magnetic field generated in the windings of the stator  90 . The oppositely directed magnetic fields interact and cause the rotor  100  to rotate, thus, rotating the shaft  110 . The shaft  110  is supported by a first bearing assembly  120  disposed at a load end  130  of the shaft  110 , and a second bearing assembly  140  disposed at a fan drive end  150  of the shaft  110 . A fan  160  is mounted to the shaft  110  at its fan drive end  150  for providing cooling flow to the motor  20  and the drive unit  50  during its operation. The fan shroud  30  defines a fan cavity  165  enclosing the fan  160  and affecting the direction of the cooling flow.  
         [0021]     Heat is generated by the motor core  80  during operation of the motor  20 . The heat generated by the motor core  80  heats the air inside the housing  70 . This heated air, if not dissipated, has a deleterious effect on the efficient operation and life of the bearing assemblies  120 ,  140  and insulation. Therefore, the fan  160  is provided to cool the motor  20 . However, because the motor and drive assembly  10  includes an integrated drive unit  50 , additional heat is also generated by the electronic circuitry used to implement the functions of the drive unit  50 . The drive unit  50  is mounted in axial alignment with the motor  20  and fan  160  such that cooling flow generated by the fan  160  also flows over the drive unit  50 , thereby removing additional heat generated by the drive unit  50 . As described in greater detail below, the drive enclosure  60  constrains the cooling flow to ensure that it is provided both to the motor  20  and the drive unit  50 .  
         [0022]     In general, the drive unit  50  includes circuitry for generating drive signals for controlling the motor  20 . The drive unit  50  includes rectifying circuitry that receives 1 or 3-phase power from an external power supply and converts the AC power to DC. Inverter circuitry in the drive unit  50  is positioned between positive and negative DC buses of the rectifier to generate the signals for driving the motor  20 . The inverter circuitry includes a plurality of switching devices (e.g., transistors) that are positioned between the positive and negative DC buses and drive leads (not shown) coupled to the motor  20 , such that by opening and closing specific combinations of the inverter switches, positive and negative DC voltage pulses are generated on each of drive leads. By opening and closing the inverter switches in specific sequences, AC voltages having controllable amplitudes and frequencies can be generated on each of the drive leads coupled to the motor  20 .  
         [0023]     As seen in  FIGS. 1 and 2 , the drive unit  50  includes a display  170  and one or more controls  180  for configuring the drive unit  50 . For example, various operating parameters, such as speed, direction of rotation, operating state (i.e., on or off), etc., of the motor  20  may be set using the control  180 . In some embodiments, the drive unit  50  may include an external data port (not shown) through which the drive unit  50  may be programmed or configured prior to installation. The particular configuration technique used to program the drive unit  50  is not material to the practice of the present invention, and may vary depending on the particular implementation.  
         [0024]     Still referring the  FIGS. 1 and 2 , the assembly of the motor and drive assembly  10  is now described in greater detail. The fan shroud  30  is mounted to the motor  20  to enclose the fan  160  by bolts  190  that extend through holes  195  in the fan shroud  30  to interface with threaded holes  200  defined in the housing  70 . The mounting bracket  40  mounts to the fan shroud  30  via bolts  210  that pass through holes  215  to interface with threaded holes  220  defined in the fan shroud  30 . The drive unit  50  mounts to the mounting bracket  40  via bolts  230  that interface with threaded holes  240  defined in the mounting bracket  40 . The mounting bracket  40  includes a generally ring-shaped body  245  and tabs  250  extending perpendicularly with respect to the body  245 . The tabs  250  include threaded holes  260  aligned with corresponding holes  270  defined in the drive enclosure  60 . Bolts  280  pass through the holes  270  in the drive enclosure  60  and interface with the threaded holes  260  defined in the tabs  250  to mount the drive enclosure  60 . A first lead opening  285  defined in the fan shroud  30  and a second, corresponding lead opening  290  defined in the mounting bracket  40  allow electrical leads (not shown) from the drive unit  50  to pass through the fan shroud  30  and mounting bracket  40  to be connected to the motor  20 .  
         [0025]     The mounting configuration shown in  FIGS. 1 and 2  is provided for illustrative purposes. Other mounting configurations may be used. For example, the drive unit  50  and/or the drive enclosure  60  may mount directly to the fan shroud  30  without an interposing mounting bracket.  
         [0026]     In general, the fan shroud  30  and drive enclosure  60  cooperate to define the path for cooling air flow generated by the fan  160 . In the illustrated embodiment, the fan  160  is bidirectional, such that regardless of the direction of rotation of the motor  20 , cooling air flows in the direction provided by the arrow  300  shown in  FIG. 3 .  
         [0027]     As seen in  FIGS. 2 and 3 , the drive enclosure  60  includes vents  310  and a window  320 . The window  320  is generally provided to allow access to the drive enclosure  60  by an operator, however, in an embodiment where the drive unit  50  is preconfigured, the window  320  may be omitted. Also, in some embodiments, a gasket (not shown) corresponding to the geometry of the window  320  may be provided to provide a seal between the drive unit  50  and the drive enclosure  60  to reduce the likelihood that foreign material is drawn into the drive enclosure  60 .  
         [0028]     Intake air for the fan  160  enters the drive enclosure  60  through the vents  310 . The drive enclosure  60  defines a drive cavity  330  surrounding the drive unit  50 . Heat generated by the drive unit  50  heats the air present in the drive cavity  330 . Because the intake air for the fan  160  is drawn in through the vents  310  and into the drive cavity  330 , the heat from the drive unit  50  is dissipated by the intake component of the cooling flow. In the illustrated embodiment, the vents  310  are defined by openings in the drive enclosure  60  that spell the word “MASTER.” However, other vent geometries may be used.  
         [0029]     The fan shroud  30  includes one or more openings  340  to allow the passage of intake cooling flow through the fan shroud  30 . The mounting bracket  40  includes a central opening  350  corresponding to the opening  340  defined in the fan shroud  30 . Hence, intake air enters the drive enclosure  60  through the vents  310 , traverses the drive unit  50 , and passes through the opening  350  defined in the mounting bracket  40  and the opening  340  defined in the fan shroud  30  to reach the fan  160 . Again, this direction of flow is indicated by the arrow  300  shown in  FIG. 3 . Hence, the intake component of the cooling flow cools the drive unit  50  prior to reaching the fan  160 . The exhaust portion of the cooling flow generated by the fan  160  passes through the motor core  80  and exits through ports (not shown) defined in the housing  70  proximate the load end  130  of the shaft  110 , thereby cooling the motor core  80 .  
         [0030]     The motor and drive assembly  10  of the present invention provides cooling flow for the drive unit  50  without necessitating auxiliary cooling, additional heat sinks, or modifications to the motor  20  or housing  70 , thereby reducing the cost and complexity of the motor and drive assembly  10 . The cooling flow generated by the fan includes an intake component that cools the drive unit  50  and an exhaust component that cools the motor  20 .  
         [0031]     The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.