Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Reexamination Certificate
1999-07-02
2001-12-04
Dinkins, Anthony (Department: 2831)
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
C361S306100, C361S308100
Reexamination Certificate
active
06327133
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to capacitor assemblies, and more particularly, to a capacitor assembly having a monolithic construction designed to easily and efficiently mount to an external device, such as a motor.
BACKGROUND OF THE INVENTION
Capacitors have many industrial uses. For example, motors used for compressors, pumps, and refrigeration and air conditioning equipment typically utilize a capacitor to improve the starting and/or operating performance of the motor. In many cases, however, the capacitor is not an integral component of the motor and must be mounted to the motor's housing prior to operation. Typically, this is accomplished by using a special bracket or by placing the capacitor within a shell and fastening the entire assembly to the motor housing.
A conventional capacitor assembly is shown in FIG.
1
. This assembly includes a capacitor, an insulating board, and a metal shell commonly referred to as a “doghouse.” The capacitor is completely sealed within a phenolic case and has terminals which extend from an open end in the case. Prior to operation, a user must electrically connect the motor to the capacitor's terminals and insert the phenolic case into the “doghouse.” The insulating board is placed between the capacitor's terminals and the “doghouse” to prevent electrical shorts during operation. Once the individual components have been assembled, the “doghouse” must be securably fastened to the motor housing.
Conventional capacitor assemblies such as those exemplified in
FIG. 1
have several shortcomings. For example, as discussed above, the capacitor assembly shown in
FIG. 1
requires considerable assembly prior to operation. The user must first connect the terminal leads from the capacitor to the motor. In many situations, this typically involves the user soldering the motor leads to the capacitor terminals. Moreover, assembly is made more difficult due to the fact that the capacitor's terminals extend outward from the capacitor body instead of in a direction facing the motor housing.
Moreover, the capacitor assembly shown in
FIG. 1
requires a snug fit between the phenolic case and the “doghouse.” Thus, in a situation where the phenolic case is too large, it may not fit into the “doghouse,” further increasing the difficulty of assembly. Similarly, in a situation where the phenolic case is too small, the resulting capacitor assembly is unstable and susceptible to motor vibrations.
Furthermore, conventional capacitor assemblies are often very large and heavy with respect to their intended use. Despite the electrical requirements for the capacitor, the size and weight of the assembly is largely dependent upon the phenolic shell and metal “doghouse.” As described above, the capacitor body is first inserted and sealed within the phenolic case which in turn must fit within the metal “doghouse.” The resulting capacitor assembly is often unnecessarily large and heavy. Typically, capacitor assemblies made according to the prior art have a diameter substantially equal to the diameter of the motor housing. Moreover, in order to customize an existing assembly, a user must specify changes in the size of the phenolic case as well as the metal “doghouse.”
Accordingly, there arises a need to provide a monolithic capacitor assembly having substantially the same performance characteristics as conventional capacitor assemblies yet, with the added feature of being easy to assemble/mount prior to operation. Furthermore, there is a need to provide a capacitor assembly that is sized appropriately for the needed application. Such a capacitor assembly would provide a more efficient and secure method of assembly and substantially reduce costs associated with installation. The present invention directly addresses and overcomes the shortcomings of the prior art.
SUMMARY OF THE INVENTION
The present invention relates to a monolithic capacitor assembly designed to easily and efficiently mount to an external device, such as a motor. The capacitor assembly includes a capacitor electrically coupled to an electrical termination. The capacitor assembly also includes a cylindrical nylon shell which has a mounting surface enabling the capacitor assembly to be securably attached to a motor housing. In a preferred embodiment of the present invention, the mounting surface is cured to correspond to the outside of a motor housing. The nylon shell has an open end which defines a cavity centrally disposed within the nylon shell. The cavity is sized and configured to receive the capacitor and the electrical termination such that the electrical termination is positioned within an indentation in the mounting surface at the open end of the nylon shell. The electrical termination extends outward from the nylon shell in a direction perpendicular to the mounting surface of the nylon shell. In one embodiment of the present invention, the electrical termination includes at least two solid or stranded lead wires extending through the indentation in the mounting surface. In an alternate embodiment of the present invention, the electrical termination is a standard electrical termination device, such as a a quick disconnect terminal connector or an insulation displacement connector.
The capacitor assembly of the present invention is further enhanced by filling the nylon shell with an epoxy endfill after the capacitor and electrical termination have been inserted within the nylon shell cavity. The epoxy endfill protects and seals the capacitor and the electrical termination, thereby ensuring the integrity of the electrical connection made between the capacitor and the electrical termination during both installation and operation.
Where the electrical termination is an electrical termination device, such as an insulation displacement connector, the epoxy endfill is applied in stages. A first epoxy endfill secures the capacitor within the nylon shell to a first level. This first level completely seals the capacitor and is in close proximity with the insulation displacement connector. Similarly, a second epoxy endfill completely seals the electrical connection between the capacitor body and the insulation displacement connector.
A capacitor assembly according to the present invention is produced by first electrically coupling the capacitor to the electrical termination. The capacitor and electrical termination are next inserted into the cavity of the nylon shell and secured such that the electrical termination extends through the indentation in the mounting surface. The nylon shell is next rotated so that it stands on its closed end. The nylon shell is then filled with an epoxy endfill which protects and seals the electrical connection between the capacitor and the electrical termination.
Where the electrical termination is an electrical termination device, such as an insulation terminal connector, the epoxy endfill is filled to a first level within the nylon shell. This first level defines a point within the nylon shell where the capacitor body is completely sealed and is in close proximity with the electrical termination device. After the first epoxy endfill is allowed to cure, the nylon shell is rotated so that it rests on its side opposite the mounting surface. The open end of the nylon shell is partially covered to allow the nylon shell to be filled with a second epoxy endfill. The second epoxy endfill level is perpendicular to the plane of the first epoxy endfill level and is flush with the open end of the nylon shell. Moreover, the second epoxy endfill extends to a level in close proximity with the electrical termination device leaving a recess within the nylon shell. The electrical termination device is positioned in the recess such that it rests within the indentation and faces a direction perpendicular to the mounting surface.
The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Other objects, features and advantages of the present invention will become more appar
American Shizuki Corporation
Dinkins Anthony
Merchant & Gould P.C.
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