This invention relates generally to electrical connectors. More particularly, the invention relates to a plug for connecting electrical leads to the terminal posts of a hermetic compressor for use in a refrigeration or air conditioning system.
A large percentage of the hermetic refrigeration and air conditioning compressors in use or being manufactured today have a terminal assembly for conducting electrical power through the shell of the compressor. FIG. 1 shows a typical terminal assembly 40 having a body member 41 with a shoulder 43. At least two, and usually three, axially aligned terminal posts 42 pass through body member 41, with each post 42 having inner end 42I and outer end 42O.
FIG. 2 shows terminal assembly 40 mounted in the upper portion of shell 51 of compressor 50. Body member 41 extends through shell 51 and is welded or otherwise secured to shell 51 with the shoulder 43 extending a short distance beyond the outer surface of shell 51. Electrical leads 62 from the compressor motor (not shown) connect to inner ends 42I by means of connector plug 61. Electrical power is supplied to the compressor by a plug and leads (not shown) connected to post outer ends 42O. Power leads may be individually connected to the terminal posts, or the leads may terminate in a common connector plug that connects to the posts. FIGS. 3 and 4 depict such a plug 80 in which each electrical lead 83 terminates in its own axially aligned connector cavity 82 in plug body 81. As will be seen in FIG. 4, plug 80 does not completely cover terminal posts 42 when it is installed.
Referring again to FIG. 2, some, but not all, compressors have thermal sensor 71, mounted on the top of shell 51 in proximity to terminal assembly 41. Sensor 71 monitors the temperature of shell 51 for purposes of overload protection. An abnormally high shell temperature would indicate that there is an overload condition in the compressor. If the shell temperature reaches such a predetermined value, a signal from sensor 71 initiates a system shutdown to protect the compressor. Stud 52 is secured to and extends from shell 51, and cover 54 fits over terminal assembly 41 and sensor 71 with nut 53 securing the cover in place. Cover 54 engages a portion of the thermal sensor 71 to hold it in place, and also prevents the insertion of foreign objects, such as tools, between plug 80 and terminal assembly 43. Foreign objects could cause an electrical short circuit between or among terminal posts 42. Cover 54 also prevents moisture from reaching terminal posts 42.
If the external power leads do not terminate in a common connector plug, it is easily possible to connect the leads incorrectly. Even if there is a connector plug like plug 80 (FIGS. 3 and 4), because of the configuration and orientation of the terminal posts with respect to each other, it is possible to install the plug incorrectly and therefore connect a lead to an incorrect post. If the leads are installed incorrectly, improper operation or damage to the compressor may result.
In order to simplify assembly, reduce the number of parts and therefore reduce costs, it would be desirable to eliminate the cover 54 (FIG. 2). What is needed is an improved device that reduces the possibility of incorrectly connecting the external electrical power leads to the terminal assembly of a hermetic compressor, protects the terminal posts from exposure to incidental moisture and short circuiting, and eliminates the need for a separate connector cover. If there is a thermal sensor, the device should also be capable of holding it in place. The device should be adaptable for use with a compressor with no modification to the compressor itself.