US20090092506A1

US20090092506A1 - Rotor attachment for compressor

Info

Publication number: US20090092506A1
Application number: US12/246,728
Authority: US
Inventors: David K. Haller
Original assignee: Tecumseh Products Co
Current assignee: Tecumseh Products Co
Priority date: 2007-10-09
Filing date: 2008-10-07
Publication date: 2009-04-09
Also published as: CA2640539A1

Abstract

A compressor having drive assembly including a crankshaft and a motor having a stator and a rotor. The rotor is received on a crankshaft and secured to the crankshaft via a counterweight. In one exemplary embodiment, the counterweight is shrink-fit or press-fit in position on the crankshaft and the rotor is attached to the counterweight. In one exemplary embodiment, the rotor may be secured to the counterweight by fasteners, such as bolts. The interference between the counterweight and the crankshaft is sufficiently strong to transfer driving loads from the rotor and through the counterweight to drive the crankshaft. In one exemplary embodiment, the rotor includes a central opening having a diameter larger than the diameter of the crankshaft. This allows for the rotor to fit closely to the crankshaft without touching the same. As a result, the rotor may be easily assembled as a slip-fit on the crankshafts and then secured to the counterweights.

Description

BACKGROUND

1. Field of the Invention.
The present invention relates to compressors and, particularly, to compressors having a rotatable counterweight.
2. Description of the Related Art.
Compressors generally have a drive assembly including a motor having a stator and a rotor, in which the rotor is press-fit or shrink-fit to a crankshaft to rotate the crankshaft and drive a compression mechanism. Due to eccentric loading that occurs during the rotation of the compression mechanism, counterweights are attached to the rotor to facilitate even weight distribution during operation of the compressor. However, some rotors have magnets contained therein that may become demagnetized if they are heated to facilitate a shrink fit. Alternatively, the magnets and/or rotor may become damaged if the rotor is forced on the crankshaft to facilitate a press-fit. Additionally, when utilizing rotors containing magnets, the necessary manipulation of the rotor and extra assembly operations may be difficult.
What is needed is an improvement over the foregoing.

SUMMARY OF THE INVENTION

The present invention provides a compressor having drive assembly including a crankshaft and a motor having a stator and a rotor. The rotor is received on a crankshaft and secured to the crankshaft via a counterweight. In one exemplary embodiment, the counterweight is shrink-fit or press-fit in position on the crankshaft and the rotor is attached to the counterweight. In one exemplary embodiment, the rotor may be secured to the counterweight by fasteners, such as bolts. The interference between the counterweight and the crankshaft is sufficiently strong to transfer driving loads from the rotor and through the counterweight to drive the crankshaft. In one exemplary embodiment, the rotor includes a central opening having a diameter larger than the diameter of the crankshaft. This allows for the rotor to fit closely to the crankshaft without touching the same. As a result, the rotor may be easily assembled as a slip-fit on the crankshaft and then secured to the counterweight.
Advantageously, by limiting the need to shrink-fit or press-fit the rotor to the crankshaft, any potential distortion of the rotor is substantially eliminated. For example, if the rotor includes magnets, such as rare earth magnets, demagnetization of the magnets in the rotor is substantially prevented. Additionally, the rotor may be purchased magnetized, eliminating additional manufacturing costs and decreasing the difficulty in assembling the rotor to the crankshaft. Further, in order to press-fit the rotor to the crankshaft, a relief is commonly formed in the crankshaft to allow the rotor to be press-fit over a small distance. By eliminating the need to press-fit the rotor to the crankshaft, the need to machine a relief into the crankshaft is eliminated and the corresponding manufacturing time and cost decreased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawing, wherein:

FIG. 1 is a cross-sectional view of the drive assembly of the present invention.

Corresponding reference characters indicate corresponding parts. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

Referring to FIG. 1, crankcase 2, bearing support 5, bearing assembly 6 and drive assembly 8 are shown in accordance with one exemplary embodiment of the present invention. Drive assembly 8 includes motor 10 having stator 12 and rotor 14. Rotor 14 is rotationally locked to crankshaft 16 via upper counterweight 18. Counterweight 18 has opening 20 configured for receipt of crankshaft 16. In order to secure counterweight 18 to crankshaft 16, counterweight 18 is shrink-fit or press-fit to crankshaft 16 or fixedly connected by a suitable fastener. Once counterweight 18 is sufficiently secured to crankshaft 16, rotor 14 is connected to counterweight 18.
In one exemplary embodiment, counterweight 18 and rotor 14 have corresponding apertures 22, 24, respectively, configured for the receipt of fasteners, such as bolts 26. Bolts 26 include an oversized head 28 and a threaded portion 30 configured for receipt of nut 32 thereon. By aligning apertures 22, 24 of counterweight 18 and rotor 14, bolt 26 may be inserted therethrough and nut 32 secured to threaded portion 30 of bolt 26. In order to facilitate the assembly of rotor 14 to crankshaft 16, rotor 14 may have an oversized aperture extending therethrough. The oversized aperture of rotor 14 allows for rotor 14 to slip-fit on crankshaft 16. In this embodiment, rotor 14 does not tightly contact crankshaft 16, but may allow for a small gap to be formed therebetween.
Additionally, lower counterweight 34 may also be secured through counterweight 18 to crankshaft 16. Specifically, lower counterweight 34 further includes aperture 36 configured for the receipt of bolt 26. By aligning aperture 36 with apertures 22, 24 in crankshaft 16 and rotor 14, bolt 26 may be inserted through apertures 22, 24, 36 and nut 32 secured to threaded portion 30 of bolt 26. Once connected via bolt 26, lower counterweight 34 and rotor 14 are rotationally secured to crankshaft 16 via counterweight 18. Thus, during operation of the compressor, rotor 14 of motor 10 is rotated and the rotation of rotor 14 is transferred via contact region 36 of counterweight 18 to crankshaft 16. Crankshaft 16 may then correspondingly rotate a compression mechanism, such as a scroll compression mechanism (not shown).
The fluid is then discharged at a relatively high discharge pressure through discharge port 32. The compressor may further include other features such as those described in U.S. Pat. No. 7,094,043 to Skinner, issued Aug. 22, 2006, and U.S. Pat. No. 7,063,523 to Skinner, issued Jun. 20, 2006, the entire disclosures of which are expressly incorporated by reference herein.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A drive assembly in a compressor, the drive assembly comprising:

a motor having a stator and a rotor;

a crankshaft connected to a compression mechanism; and

a counterweight secured to said crankshaft, said counterweight rotatably fixed to said rotor, wherein said rotor is rotatably secured to said crankshaft solely by said counterweight.

2. The drive assembly of claim 1, wherein said counterweight is secured to said crankshaft by one of a shrink-fit and a press-fit.

3. The drive assembly of claim 2 wherein said rotor is secured to said counterweight by means of at least one fastener.

4. The drive assembly of claim 3 wherein said fastener is a bolt.

5. The drive assembly of claim 1 wherein said rotor is secured to said counterweight by means of at least one fastener.

6. The drive assembly of claim 5 wherein said rotor is secured to said counterweight by means of at least one fastener.