Patent ID: 12224131

The same reference numerals refer to the same elements throughout the various Figures.

DETAILED DESCRIPTION

With reference toFIG.1, a hard start capacitor replacement unit10is shown, including a cylindrical capacitor container12and a cylindrical cap14fitted onto the container12and extending therefrom. With reference toFIG.2, the cap14may be removed from the container12, to expose the cover16of the container, an electronic relay18, and wire means20providing desired electrical connections for the hard start capacitor replacement unit10to a motor60.

The container12is preferably 21/2 inches in diameter with a length of 53/4 inches and has a plurality of capacitors therein. In the embodiment shown and with reference toFIG.3, four capacitors22,24,26and28are provided within the container12. Also in the embodiment shown, the capacitors22,24,26and28are wound in a cylindrical capacitive element30having a common element terminal32at the bottom thereof and four capacitor terminals23,25,27and29at the top thereof.

The capacitors of capacitive element30are preferably metallized film capacitors concentrically wound together as the cylindrical capacitance element30. The film is preferably polypropylene metallized with zinc and may be about 3.8 microns in thickness. This is an advantageous film for several reasons. First, start capacitors generally require a higher capacitance value than run capacitors, i.e., run capacitors generally have typical capacitance values in the range of about 15 to about 65 microfarads, whereas start capacitors may have typical capacitance values up to about 300 microfarads. Such high start capacitance values have generally been achieved with electrolytic capacitors because 300-microfarad capacitors with typical film thicknesses would be bulky and require a large container that may not fit into the space provided in an air conditioning unit or the like. However, with recognition that a start capacitor is utilized for about one second or less as the motor starts, it does not have to be rated at high voltage over a long period of time. Therefore, a thin film may be used and the required capacitance is attained in a reasonably sized capacitive element. A further advantage is that the resultant metallized film capacitive element has stable capacitance values over a relatively wide ambient temperature range, and also has a long service life.

The container is preferably filled with a dielectric fluid34and the cover16is provided with circuit interruption protection in the event the capacitive element fails, such as shown inFIG.3and described in U.S. Pat. No. 7,203,053. These are also advantages in fabricating the capacitors22,24,26and28for the hard start capacitor replacement unit10from metallized film.

Although it is preferable to provide the capacitors in a cylindrical capacitive element30wound of metallized film, the capacitors22,24,26,28may be individual wound capacitors having respective ends electrically connected to form a common terminal. The capacitive element30may be provided with more or less than four capacitors if desired. The capacitors may also be provided as two or more capacitive elements each having multiple capacitors.

It is also contemplated to make a hard start capacitor replacement unit with a single multiple value electrolytic capacitor or multiple electrolytic capacitors that may be connected to provide selectable total capacitance values. However, according to present electrolytic capacitor technology, the container for such a capacitor or capacitors would necessarily be larger than the container for a metallized film capacitive element and the capacitance value would not be as stable over ambient temperature ranges.

In the hard stand capacitor replacement unit10shown and described herein, capacitor22has terminal23and preferably has a capacitance of 48 microfarads. Capacitor24has terminal25, and also has a capacitance value of 48 microfarads. Capacitor26has capacitor terminal27, and has a value of 88 microfarads, and capacitor28has capacitor terminal29and has a value of 112 microfarads.

As perhaps as best seen inFIGS.5-8, the cover16mounts a common cover terminal40in the center thereof, and mounts capacitance value terminals42,44,46and48spaced apart from the common cover terminal40and from each other. The common cover terminal40is connected to common element terminal32of the capacitive element30and thereby to each of the capacitors22,24,26and28. The capacitance value cover terminal42is connected with the terminal23of capacitor22and the capacitance cover terminal44is connected with the capacitor terminal25of capacitor24. The capacitance cover terminal46is connected with the capacitor terminal27of capacitor26and capacitance value cover terminal48is connected with the capacitor terminal29of the capacitor28. Therefore, the capacitance values of the capacitors22,24,26,28are respectively available for wire connections at the corresponding capacitance value cover terminals42,44,46,48on the cover16of container12.

A cover insulation barrier50is also mounted to the cover16to better isolate the cover terminals. The cover insulation barrier50has a cylindrical portion52surrounding the common cover terminal40and has radial extending fins54-58that separate the other capacitance value cover terminals. An extra fin is shown, which would insulate another one or two cover terminals if an additional one or two capacitors were provided.

With reference toFIG.4, a schematic of the operation of the start capacitor replacement unit10is shown. The electronic relay18has external terminals that accept wire termination clips, so that wire connections can be made between the common cover terminal40, and the capacitance value cover terminals42,44,46and48, as well as with the start and run terminals62and64of a motor60. External terminals T-1 and T-2 of electronic relay18are internally connected with contacts70and72that may be closed by a contact bar74, all schematically shown. The electronic relay18also has external terminal T-5, and the electronic relay18has circuitry indicated at76that monitors the voltage and the dv/dt between terminals T-2 and T-5 and controls the opening and closing of the contacts70and72in response thereto. Terminals T-2 and T-5 are connected to the start and run terminals62and64of compressor motor60by wires20, so that the electronic relay is monitoring the voltage across the start and run windings. Terminal T-5 may also be connected between the start and run windings of motor60. When the contacts70and72are closed, the electronic relay18connects the selected ones of the capacitors22,24,26and28across the terminals62and64in parallel with the run capacitor66to assist in starting the motor. A bleeder resister78discharges the capacitor(s) when contacts70,72are open. A suitable electronic relay is available from Zhejiang Hongli Electric Co., Part No. HLR3800-6AM1D.

With reference toFIG.9, the hard start capacitor replacement unit10may also be used with a control or potential relay90as shown in the schematic. The relay contacts92and94are closed by contact bar74to connect selected ones of capacitors22,24,26,28across run terminals62,64of motor60, and contacts92,94are opened by coil96when the motor60starts. Bleeder resister98is provided to bleed off the capacitor charge when the contacts92,94are open.

It will also be appreciated that although the capacitors of the hard start unit10are shown connected across motor terminals62,64, the purpose of this connection is to connect the capacitors in parallel with the motor run capacitor of the motor, and any connection that accomplishes this is suitable.

InFIG.4, the capacitors22,24,26and28are connected as also shown inFIG.8, in which a first wire80connects T-1 of the electronic relay with the cover capacitance value terminal48, which selects 112 microfarads of capacitance value. Jumper wire82between capacitance value terminals48and46connects an additional 88 microfarads of capacitance value into the circuit. Wire88connects the common terminal40to terminal T-5 of the electronic relay18. Jumper wire84connecting capacitance value cover terminal46and capacitance value cover terminal44connects a further 48 microfarads into the circuit. Thus, in the configuration shown inFIGS.4and6, a total capacitance of 248 microfarads is provided to start the motor60when the contacts of the electronic relay18are closed.

It will be appreciated that a variety of capacitance values may be selected by connecting various ones of the capacitance cover terminals to each other. Some preferred connections are shown inFIGS.5-8.FIG.5shows connection of capacitor28by wire80at cover terminal48providing 112 microfarads, which is suitable for use where capacitance values in the range 108-130 microfarads are desired for the motor start.FIG.6shows connection of capacitors26and28by jumper wire82at cover terminals46and48providing 200 microfarads of capacitance value, which is suitable for desired capacitance values in the range of 189-227 microfarads.FIG.7shows all of the capacitors22,24,26,28connected into the circuit at cover terminals42,44,46and48by jumper wires82,84and86to provide a total 296 microfarads, which is suitable for use in applications requiring capacitance values in the range of 270-324 microfarads.FIG.8shows connection of capacitors28,26and24by jumper wires82and84providing 248 microfarads, for use with applications requiring capacitance values of 233-280 microfarads.

If desired, the total capacitance values connected into the circuit can be further refined with possible capacitance values of 48 microfarads, 88 microfarads, 96 microfarads, 136 microfarads, 160 microfarads, 184 microfarads and 208 microfarads, being available in addition to the 112 microfarads, 200 microfarads, 240 microfarads and 296 microfarads configurations shown above.

Once the desired capacitance value is selected by placing appropriate jumper wires on the cover terminals, the cap14may be fitted over the container12, to surround the cover terminals and electronic relay18. The hard start capacitor replacement unit10has a suitable size and shape to be accommodated in the space provided for the original start capacitor, so the hard start replacement unit10is readily accepted for mounting in existing equipment.

As a result of the foregoing, a repairman can carry the hard start capacitor replacement unit10to repair site with confidence that a failed start capacitor unit can be replaced without need to return to a shop or parts distributor in order to complete the repair.

Accordingly, a hard start capacitor replacement unit has been described which fulfills the objects of the invention herein. It will be appreciated that various changes may be made by those skilled in the art without departing from the spirit and scope of the invention, which is limited only by the following claims.