Abstract:
An electric spa motor includes a ring circling the motor and in direct contact with the motor case. The ring carries a flow of water to cool the motor and to provide heat to the flow of water to supplement a spa heater. The ring includes a passage through the ring for carrying the flow of water. The ring and the passage have cross-sections with approximately equal height and width.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to motor cooling and in particular to cooling rings rising on an electric spa pump motor case providing cooling for the motor and heat to a spa. 
   Many people enjoy using portable spas to relax. The combination of water jets provide a massage to tired muscles and heat to sooth the muscles. Unfortunately, such spas often rely on an electric heater to heat the water, and heating costs may be very high. Further, an electric motor is used to circulate water in the spa, and the motors often become very hot, shortening motor life, and sometimes limiting the length of spa use. 
   U.S. Pat. No. 4,854,373 for “Heat Exchanger for a Pump Motor,” discloses a “C” shaped outer jacket residing over a spa pump motor housing for cooling the motor and adding heat to water circulated by the motor. The jacket of the &#39;373 patent has a “C” shaped cross-section and rests over nearly the entire length of the motor housing to obtain heat transfer. 
   Other patents including U.S. Pat. No. 5,038,853 for “Heat Exchanger Assembly,” U.S. Pat. No. 5,509,463 for “Saddle Type Heat Exchanger,” U.S. Pat. No. 5,906,236 for “Heat Exchanger Jacket for Attachment to an External Surface of a Pump Motor,” U.S. Pat. No. 7,322,103 for “Method of Making a Motor/Generator Cooling Jacket,” and U.S. Pat. No. 4,516,044 for “Heat Exchanger Apparatus for Electric Motor and Electric Motor Equipped Therewith,” similarly describe jackets residing over most of the motor case. Unfortunately, electric motors commonly used on portable spa pumps include capacitor housings on the outside of the motor housing. Such capacitor housings prevent the known jackets from being used. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention addresses the above and other needs by providing an electric spa motor which includes a ring heat exchanger circling the motor and in direct contact with the motor case. The ring carries a flow of water to cool the motor and to provide heat to the flow of water to supplement a spa heater. The ring includes a passage through the ring for carrying the flow of water. The ring and the passage have cross-sections with approximately equal height and width. 
   In accordance with one aspect of the invention, there is provided a ring heat exchanger for an electric spa pump motor. Known heat exchangers used with electric motors comprise jackets extending most of the length of a motor housing of the electric motor. Unfortunately, such jackets are not suitable for use with common electric spa pump motors having capacitor housings on a large center portion of the electric motor housings. The long extent of the jackets was assumed necessary to achieve a useful result. The present invention is a significant departure from such assumptions and from the resulting heat exchangers and provides a ring heat exchanger fitting over a portion of the motor housing between the capacitor housings and ends of the motor housing and achieves an unexpected benefit to motor cooling and to heat transfer to water circulated in the spa. 
   In accordance with another aspect of the invention, there is provided a spa having an electric spa pump motor and a ring heat exchanger for cooling the electric spa pump motor. The spa includes a spa tub having a spa tub wall, water residing in the spa tub, at least one drain for receiving a flow of the water from the spa tub, and a spa pump driven by the electric spa pump motor. A first pipe carries the flow of water from the drain to the spa pump and a second pipe carries the flow of water from the spa pump to jets in the spa tub wall. The spa pump motor has a motor housing and the ring heat exchanger includes a top half assembled to a bottom half, each half being approximately half of a circle, which resides in contact with the motor housing at an end of the motor housing. One of the top half and the bottom half includes a passage for receiving a by-pass portion of the flow of water received from a first by-pass line connected to the high-pressure side of the spa pump to enter the ring heat exchanger and the other one of the top half and the bottom half includes a passage for allowing the by-pass portion flow of water to exit the ring heat exchanger through a second by-pass line carrying the by-pass portion of the flow of water from ring heat exchanger to the low-pressure side of the spa pump. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
       FIG. 1  is prior art spa. 
       FIG. 2  is a spa with ring heat exchangers according to the present invention on the spa pump motor. 
       FIG. 3  shows a perspective view of a generic spa pump motor with two ring heat exchangers according to the present invention on the spa pump motor. 
       FIG. 4  is a side view of the ring heat exchanger according to the present invention. 
       FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 4  of the ring heat exchanger according to the present invention and the flow of water through the ring heat exchanger. 
       FIG. 6A  is a detailed perspective view of a spa pump and motor with one ring heat exchanger according to the present invention on the spa pump motor. 
       FIG. 6B  is a detailed perspective view of the spa pump motor with one ring heat exchanger according to the present invention on the spa pump motor. 
       FIG. 7A  is a detailed side view of the spa pump and motor with one ring heat exchanger according to the present invention on the spa pump motor. 
       FIG. 7B  is a detailed front view of the spa pump and motor with one ring heat exchanger according to the present invention on the spa pump motor. 
       FIG. 7C  is a detailed top view of the spa pump and motor with one ring heat exchanger according to the present invention on the spa pump motor. 
       FIG. 8  is a perspective view of the ring heat exchanger according to the present invention. 
       FIG. 9A  is a side view of the ring heat exchanger according to the present invention. 
       FIG. 9B  is a front view of the ring heat exchanger according to the present invention. 
       FIG. 9C  is a top view of the ring heat exchanger according to the present invention. 
       FIG. 10  is a cross-sectional view of the ring heat exchanger according to the present invention taken along line  10 - 10  of  FIG. 9A . 
       FIG. 11A  is a perspective view of the ring heat exchanger according to the present invention separated into a top ring half and a bottom ring half. 
       FIG. 11B  is a perspective view of the top ring half separated into three main components. 
       FIG. 12  is a detailed cross-sectional view of the top ring half of  FIG. 10 . 
       FIG. 13  is a perspective view of a O-Ring retainer according to the present invention. 
       FIG. 14A  is a side view of the O-Ring retainer. 
       FIG. 14B  is an end view of the O-Ring retainer. 
       FIG. 14C  is a top view of the O-Ring retainer. 
       FIG. 15  is a top view of an O-Ring for sealing the ring heat exchanger according to the present invention. 
   

   Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
   A prior art spa  10  is shown in  FIG. 1 . The spa  10  includes drains  12   a  and  12   b . The drains  12   a ,  12   b  are located below a spa water line  26   a  and are in fluid communication with a pump  14  and pump motor  32  through first pipes  16   a  and  16   b  carrying flows  17   a  and  17   b  of water  26  respectively, and combined through pipe  16 , through a filter  13  and to the pump  14 . A spa heater  18  is in fluid communication with the pump  14  through a second pipe  20  carrying second flow  21 . The heater  18  is in fluid communication with jets  22  through pipe  24  carrying a heated flow  25  to the jets  22 . The water is returned to the spa by the jets  22  creating turbulence  27  in the spa. The pump motor  32  resides inside a spa enclosure  28  and often reaches high temperatures which may shorten motor life, or cause a thermal switch to trigger, turning off the spa  10 . 
   A spa  10   a  according to the present invention is shown in  FIG. 2 . The spa  10   a  is similar to the prior art spa  10 , except that the spa  10   a  includes two ring heat exchangers  30  circling the motor  32  and a first bypass line  31   a  carrying a bypass flow portion  21   a  of the flow  21  from a high-pressure side of the spa pump  14  to the ring heat exchangers  30 , a second bypass line  31   b  the bypass flow portion  21   a  between the ring heat exchangers  30 , and a third bypass line  31   c  carrying the bypass flow portion  21   a  back to the flow  21  at a low-pressure side of the spa pump  14 . The bypass line  31   a  is preferably connected to the line  20  after the pump  14  where pressure is high, and the bypass line  31   c  is preferably connected to the line  16  before the pump  14  where pressure is low, thereby creating a flow through the ring heat exchangers  30 . The bypass lines  31   a ,  30   a , and  30   c  preferably are connected to the lines  20  and  16  respectively by collars  33 . 
   A perspective view of a generic spa pump motor with two ring heat exchangers  30  according to the present invention on the spa pump motor housing  36  is shown in  FIG. 3 , a side view of the ring heat exchanger  30  is shown in  FIG. 4 , and a cross-sectional view of the ring heat exchanger  30  showing a the flow of water through a path  58  in the ring heat exchanger  30  taken along line  5 - 5  of  FIG. 4  is shown in  FIG. 5 . The spa pump motor includes at least one capacitor housing  38  preventing jackets disclosed in the prior art from being placed over a motor housing  36  of the spa pump motor  32 . The ring heat exchangers  30  according to the present invention fit over ends of the motor housing  36  avoiding interference with the capacitor housing(s)  38 . The ring heat exchangers  30  include a passage  60  receiving a portion of the flow  21  and another passage  60  releasing the portion of the flow  21 . The bypass flow portion  21   a  of the flow  21  (see  FIG. 2 ) enters the inlet  60   a , circles the housing  36 , and exits through the outlet  60   b . The bypass flow portion  21   a  of the flow  21  both cools the spa pump motor  32  and provides heat to the flow  21  to reduce heating requirements. 
   The bypass lines  31   a ,  30   a , and  30   c  are preferably ¾ inch tubing and the bypass flow portion  21   a  of the flow  21  is preferably at least 15 gallons per minute, and more preferably at least 20 gallons per minute. 
   While the present invention is shown having two ring heat exchangers  30 , in some embodiments either a single ring heat exchanger  30  may be adequate, or room may only permit a single ring heat exchanger  30 . Such embodiments with more or less than two ring heat exchangers  30  are intended to come within the scope of the present invention. 
   Because the heat transfer rings  30  according to the present invention are significantly different from jackets disclosed in the prior art, tests were performed to determine whether or not, the heat transfer rings  30  provided useful cooling. A box was constructed having an interior volume approximately equal to the volume which the spa pump motors reside in. A Megaflow® model, MF23036, 230 V, 14 amp pump and motor assembly was tested for approximately 60 minutes. Pipes were connected to the pump and connected to a 300 gallon reservoir. After one hour of operation, the pump motor increased from 62 degrees Fahrenheit to 211 degrees Fahrenheit, an increase of 147 degrees Fahrenheit. After an additional seven minutes of operation, the motor thermal overload tripped and shut down the motor. 
   A second test was performed with heat transfer rings  30  according to the present invention residing over the motor housing. After one hour of operation, the motor temperature increased from 62 degrees Fahrenheit to 174 degrees Fahrenheit, an increase of 112 degrees Fahrenheit. The increase in motor temperature was reduced by 35 degrees Fahrenheit which significantly extends run time by eliminating tripping the thermal overload and significantly increases pump motor life. Additionally, transferring the heat to the water circulated in the spot reduces the amount of heating required, thus providing additional cost savings. 
   A detailed perspective view of a spa pump  14  and motor  32  with one ring heat exchanger  30  according to the present invention on the spa pump motor  32  is shown in  FIG. 6A  and a detailed perspective view of the spa pump motor  32  only with one ring heat exchanger  30  on the spa pump motor 32  is shown in  FIG. 6B . The ring heat exchanger  30  is seen to reside directly against the motor housing  36  at an end of the motor housing  36  avoiding the capacitor housings  38 . 
   A detailed side view of the spa pump  14  and motor  32  with one ring heat exchanger  30  on the spa pump motor  32  is shown in  FIG. 7A , a detailed front view of the spa pump and motor with one ring heat exchanger on the spa pump motor  32  is shown in  FIG. 7B , and a detailed top view of the spa pump  14  and motor  32  with one ring heat exchanger  30  on the spa pump motor  32  is shown in  FIG. 7C . Two capacitor housings  38  reside on the motor housing  36  and the motor  32  is supported by a motor mount  39 . The ring heat exchanger  30  resides at the pump  14  end of the motor  32  fitting between the motor mount  39  and the end of the housing  36 . 
   A detailed perspective view of a preferred ring heat exchanger  30  according to the present invention is shown in  FIG. 8 , a side view of the ring heat exchanger  30  is shown in  FIG. 9A , a front view of the ring heat exchanger  30  is shown in  9 B, and a top view of the ring heat exchanger  30  is shown in  FIG. 9C . The ring heat exchanger  30  includes a top half  42  and a bottom half  44 . The top half  42  and the bottom half  44  are each approximately one half of a complete circle forming the ring heat exchanger  30 , each half is not necessarily an exact half circle, but is near enough to a half circle to allow the ring heat exchanger  30  to be easily assembled over a cylindrical motor housing. The top half  42  and the bottom half  44  form two semi circles connected at ends by two pairs of screws  62 . One of the top half  42  and the bottom half  44  receives the bypass flow portion  21   a  of the flow  21  into the heat transfer ring  30  and one of the top half  42  and the bottom half  44  releases the bypass flow portion  21   a  of the flow  21  from the heat transfer ring  30  (see  FIG. 5 ). Barbed fittings  40  are shown attached to each of the top half  42  and the bottom half  44  for receiving and releasing the bypass flow portion  21   a  of the flow  21 . 
   A cross-sectional view of the ring heat exchanger  30  according to the present invention taken along line  10 - 10  of  FIG. 9A  is shown in  FIG. 10 . The top half  42  and the bottom half  44  are seen to each include a base  50 , and cap  46 , and an O-Ring retainer  48  between the base  50  and the cap  46  and attached to the cap  46 . 
   A perspective view of the ring heat exchanger  30  separated into the top ring half  42  and the bottom ring half  44  is shown in  FIG. 11A . The top ring half  42  includes a cylindrical female connector  54  for insertion into a cylindrical male connector  56  in the bottom ring half  44 , the connectors  54  and  56  opposite the passages  60  on each ring half  42  and  44 . O-rings  52  preferably reside in grooves in the connector  54  to provide a seal with the connector  56 . The top ring half  42  is attached to the bottom ring half  44  by the two pairs of screws  62  shown in  FIG. 9A . 
   A perspective view of the top ring half  42  separated into three main components, the base  50 , the cap  46 , and the O-Ring retainer  48  are shown in  FIG. 11B . The O-Ring retainer  48  is attached to the cap  46  by three spaced apart screws  49 . The screws  49  are preferably stainless steel screws or made from some other corrosion resistant material. 
   A detailed cross-sectional view  12  of the top ring half of  FIG. 10  is shown in  FIG. 12 . The ring heat exchanger  30  has a width W R  which is preferable less than approximately two inches to allow the ring heat exchangers  30  to reside against the motor housing  36  between the capacitor housings  38  and ends of the motor housing  36 . The path  58  carries the portion of the bypass flow portion  21   a  of the flow  21  through the ring heat exchanger  30  (see  FIG. 5 ). An O-Ring  47  resides between adjacent walls of the base  50  and the cap  46  to prevent water from leaking from the ring heat exchangers  30 . The O-Ring  47  is installed with O-Ring lubricant. The O-Ring retainer  48  holds the O-Ring  47  in position. While such O-Ring retainer is generally not necessary between two flat surfaces, because the cooperating sealing surfaces of base  50  and the cap  46  are arced, the O-Ring retainer  48  is preferred. 
   A perspective view of the O-Ring retainer  48  element according to the present invention is shown in  FIG. 13 , a side view of the O-Ring retainer  48  is shown in  FIG. 14   a , an end view of the O-Ring retainer  48  is shown in  FIG. 14B , and a top view of the O-Ring retainer  48  is shown in  FIG. 14C . The O-Ring retainer has a “T” shaped cross-section (see  FIG. 12 ) for accepting the O-Ring  47  (see  FIG. 12 ) and is attached to the cap  46 . 
   A top view of the O-Ring  47  is shown in  FIG. 15 . 
   While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.