Patent Application
20110135517
This application relates to a way to hold a smaller diameter electric motor in a larger diameter sealed compressor center shell, wherein the center shell is deformed to contact an outer periphery of the motor stator.
Sealed compressors are known, and typically include a center shell housing an electric motor and a compressor pump unit. End caps are attached to each end of the center shell. The center shell is cylindrical, and the electric motor has a cylindrical outer diameter stator which is force-fit or otherwise secured within the center shell.
For compressors with higher capacity for a given motor diameter, it is often typical for the compressor pump unit to become of a larger diameter than is required by the motor. Thus, the center shell must also have a larger inner diameter to accommodate the compressor pump unit.
It is not necessary to utilize a larger diameter motor, as the existing motors are typically of sufficient power to power the larger compressor pump units. Thus, some method of securing the electric motor within the center shell becomes necessary.
It has been proposed in the prior art to utilize a cylindrical ring spacer between an outer periphery of the motor stator and the inner periphery of the cylindrical shell. However, this cylindrical ring would raise challenges for assembly.
A sealed compressor includes a cylindrical shell extending along an axis. A compressor pump unit is mounted within a housing defined by the cylindrical shell. An electric motor has an inner rotor and an outer stator. The stator has an outer peripheral surface of a first dimension. The center shell has a nominal inner diameter, greater than the first dimension of the stator. The rotor drives a driveshaft about the axis. The driveshaft is associated with the compressor pump unit. A suction port extends through the center shell to deliver a suction fluid to be compressed by the compressor pump unit. Some of the suction fluid flows into a gap defined between the nominal inner diameter of the center shell and the outer periphery of the stator. The center shell has portions deformed radially inwardly to contact the outer periphery of the stator.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
An electric motor 30 drives the rotating shaft 48. The electric motor 30 includes a rotor 35 and a stator 33. As mentioned above, in many modern compressor applications, the outer diameter of the compressor pump say, the crank case 26 and non-orbiting scroll member 22, for example, is larger than the outer diameter of the motor stator 33.
In operation, refrigerant enters the compressor 20 through a suction tube 40, and moves upwardly into the compression chambers. The refrigerant is compressed and moves to an outlet port 100, into a discharge plenum 101, and ultimately to a discharge port 42.
A housing provides hermetically sealed chambers, and also provides a seal between the discharge plenum 101, and a suction pressure plenum 103. The housing includes an upper end cap 130, a lower end cap 132, and a cylindrical shell 28 extending between the two end caps.
The cylindrical shell is formed with radially inwardly extending deformed portions 44. The deformed portions 44 are deformed inwardly, such that they will define an inner diameter, which is less than an outer diameter of the stator 33. The stator 33 can then be force-fit into the center shell 28, and the deformed portions 44 will lock on and hold the rotor 33 within the center shell 28 at a desired location. Further, there is a gap 38 between the outer diameter 36 of the rotor 33, and the inner diameter of the center shell 28 at locations other than the deformed portions 44. In this embodiment, the deformed portions 44 are generally formed along a spiral. The deformed portions 44 thus form a spiral path at the undeformed portions. Some suction refrigerant from suction tube 40 may pass downwardly and through the gap 38, and into the path, to pass along the outer periphery of the stator 33, and then move back upwardly between the rotor 35 and the stator 33 to cool the motor.
While a spiral path generally along a helix is specifically disclosed, other continuous path shapes may come within the scope of this invention. Essentially, the continuous path has a begin point spaced toward the compressor pump unit, and an end point spaced away, and the continuous path defines a flow path for the refrigerant through the gap defined the center shell and the stator.
In addition, a counterweight 50 is mounted to rotate with the driveshaft 48, and has an outer peripheral portion 52 which is configured to drive the refrigerant downwardly towards the space 38. The counterweight 50 has an outer peripheral extent which extends radially outwardly over the radially innermost portion of the stator 33. Details of this counterweight are disclosed in co-pending U.S. patent application Ser. No. ______, filed on even date herewith, and entitled “Scroll Compressor Counterweight With Cooling Flow Directing Surface.”
The disclosed invention thus provides a simple way of mounting a smaller diameter motor in a larger diameter center shell. Assembly is no more complex than the existing prior art wherein the center shell is sized to be equal to the outer diameter of the motor. In preferred embodiments, the surface area of the deformed portions is sufficient to secure the stator without any further required attachments (i.e., no adhesives, etc. required).
Although embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
