Patent Publication Number: US-3878809-A

Title: Air-cooled electric outboard motor

Description:
United States Patent 11 1 Ray 1 Apr. 22, 1975 AlR-COOLED ELECTRIC OUTBOARD MOTOR [76] Inventor: Morton Ray, 3801 Moss Dr..  
 [52] U.S.Cl. 115/18 E; 310/62 [51] Int. Cl. B63h 1/04 [58] Field of Search 115/17, 18 E, 18 R, 34 R; 310/59. 58. 56, S7, 62  
 [56] References Cited UNITED STATES PATENTS 2336774 5/1960 Holley et al. 310/62 X 3.013.518 12/1961 Smith ll5/l8E 3.553.505 1/1971 Sato 310/68 D 3.575.524 4/1971 Adajian 310/62 Primary Etaminer-Trygve M. Blix Assistant E.\&#39;aminerGregory W. OConnor [57] ABSTRACT An air-cooled electric outboard motor includes a power unit having air intake and exhaust ports shielded from the weather by being provided in a bottom wall of a housing for the power unit. An electric motor having a cylindrical housing is mounted verti&#39; cally in the housing. The motor includes an output shaft passing through the bottom of the power unit for driving a propeller type lower drive unit. The motor has top and bottom end bell housings with radially facing inflow and outflow orifices respectively and a centrifugal fan is mounted on the output shaft radially within the bottom bell housing. Baffle plates extend upward from the bottom of the housing between the intake and exhaust ports, Speed control components are mounted on the baffle plates and the plates are so positioned to direct air entering the intake ports to flow upward over the speed control components. A directive shroud around the bottom end bell causes the outflow orifices of the motor to communicate with the exhaust ports, while the inflow orifices are in communication with the intake ports by means of the enclosed interior of the power unit housing. The fan drives the dual pass circulating air flow within the power unit, first passing upward over the speed control components and then downward through the motor.  
 7 Claims, 7 Drawing Figures PATENTEU APR 2 2 I975 SHEET 1 Bf 3 kF/GTZ AIR-COOLED ELECTRIC OUTBOARD MOTOR FIELD OF THE INVENTION This invention relates generally to electric outboard motors. and more particularly. to the dual pass air cooling of the power unit of such an outboard motor via air intake and exhaust ports in a bottom wall of the power unit housing.  
 BACKGROUND OF THE INVENTION Heretofore. convection cooled electric outboard motors. have been used on small boats. primarily-as auxiliary motors for low power. low speed. relatively silent operation applications. such as for trolling. Generally. an internal combustion outboard motor has provided the motive power for high speed. While electric motors provide various advantages over internal combustion engines. such as the ability to electrically reverse rotation and control speed. obviating the need for expensive mechanical moving parts in the motor and complicated mechanical transmissions. the elimination of sources of water and noise pollution. minimal maintenance and running expense. relatively high power electric outboards have not generally been used.  
  It is believed that this lack of use is primarily due to the fact that there is no available. inexpensive and reliable technique of intensely cooling an electric outboard motor to obtain high power performance front a motor of small dimensions and relatively light weight.  
  Basically. the prior art in electric outboard motor construction has not solved the problem of integrating a motor/fan combination within an electric outboard motor housing in a manner which is reliable in the harsh marine environment. The cooling capacity required for large electric motors has not previously been attained. in so far as I am aware. Problems have also arisen concerning the intake of debris. foreign matter. precipitation. water spray and corrosive materials along with the cooling air.  
  Furthermore. there is a need in large motors to pro title for the cooling of ancillary components of an electric outboard motor. such as solid state speed control devices.  
 OBJECTS OF THE INVENTION Thus. it is an object of the present invention to provide a new and improved air cooled electric outboard motor with a dual pass air flow and having air intake and exhaust ports located to be shielded from the weather and from the intake of debris.  
  It is a further object of the present invention to provide a new and improved air-cooled electric outboard motor utilizing a commercially available electric motor/fan combination.  
  It is another object of the present invention to pro vide a new and improved air cooled electric motor with means for cooling ancillary electric circuitry.  
 SUMMARY OF THE INVENTION In the present invention. an air-cooled electric outboard motor is provided having air intake and exhaust ports on the underside of the power unit housing so as to be shielded from the weather. Baffle means extend upward from the housing base between the intake and exhaust ports. A standard d.c. electric motor is vertically disposed in the housing in an inner chamber defined within the baffle means with a fan driven by the (ill output shaft located in the lower end bell housing. The fan sets up a circulation of air within the housing in which air is drawn through the intake ports upward into a vertically elongated outer chamber or channel defined between the baffle means and the housing. over the top of the baffle means and down through the motor and out the exhaust ports. The outer chamber provides space for mounting ancillary components. such as solidstate speed control devices and relays in the intake air stream to allow for cooling the devices. The baflIe means. normally plates. serve the dual pur pose of directing the air flow over the ancillary components and providing a structure on which to mount these components.  
  Other objects and features of the present invention will become apparent upon a perusal of the following detailed description of a preferred embodiment taken in conjunction with the appended drawings.  
 BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view of the electric outboard motor assembly of the present invention with a portion of the power unit housing broken away to espose the parts therein:  
  FIGv 2 is an exploded isometric side view illustrating the assembly of the power unit;  
  FIG. 3 is an elevation view of a motor/fan combination within the power unit:  
  FIG. 3A is a partial cross-section view of FIG. 3 showing the centrifugal fan;  
  FIG. 4 is a crosssectional side view of a base for the power unit;  
  FIG 5 is a cross-sectional side view of the power unit illustrating the dual pass flow of cooling air. and  
  FIG. 6 is a partial horizontal cross-sectional \iew along the lines h-6 of FIG. 5.  
 DETAILED DESCRIPTION OF THE DRAWING Referring to FIG. I. the electric outboard motor assembly III of the present invention includes a power unit I2 containing a vertically oriented air-cooled electric motor [4 having a downwardly directed output shaft [6 passing through base [5. The shaft 16 drivingly engages the drive means of lower drive unit [8 directly below the power unit. The drive unit 18 serves to rotate propeller I) in response to rotation of the motor output shaft 16 in an obvious manner. The motor is fed from an external electric storage battery 20. such as a cow ventional lead-acid battery. via speed control circuitry 2|. preferably mounted in power unit 12 so as to be aircooled and responsive to a manual control grip 22 on the tiller arm or handle 25 on the outside of the power unitv Outboard motor assembly [0 further comprises a conventional mounting 23 for attaching the lower drive unit 18 to the transom of a boat including a C clamp type device 24. The tiller arm 25 extends horizontally from the power unit base [5 to provide the means for manually rotating the motor assembly 10 about a generally vertical axis in mounting 23 for steering purposes. Control grip 22 is conveniently mounted at the end of tiller arm 25 and operates a potentiometer within enlarged portion 25a of the arm for controlling on-off operation and the speed of the motor assembly 10 in a conventional manner. Control grip 22 may utilize an integral shaft and a rotary switch (not shown) to control the on-off operation and for reversing the direction of the motor via suitable contactors.  
  Power unit l2 comprises a housing formed of a cover 26 fitting over the base IS; the cover 26 and base I preferably having a streamlined oval cross&#39;section. A handle 28. which extends upwardly from the top of cover 26, is used for tilting the outboard unit out of the water in a conventional manner.  
  The base I5. as best shown in FIGS. 2 and 4 is prefer ably a cast aluminum part. having a bottom oval wall 30. smoothly merging into an upwardly directed sidewall 32 around the periphery ofthe oval shape. The top of the periphery. of sidewall 32 has a step 34 including a horizontal shoulder 36 providing a seat for the cover 26. A tubular shank 38 extends downwardly from a hole 39 in the center of bottom wall 30. Shank 38 is received by the lower unit 18 with the shaft I6 extending from motor [4 through opening 39 (see FIGS. 2 and 5 I.  
  For advantageously shielding the air-cooling system front the intake and blowing of debris and precipita lion. air intake and exhaust ports or apertures 40 and 42. respectively. are both prmided in the bottom wall of base [5. This assures that the air both being sucked in and blown out is shielded from above by the power unit I2 itself. Falling debris or precipitation is thus not susceptable to being in interference with the important cooling function. An additional advantage lies in that the noise level is reduced with respect to the occupants of the boat since the ports and 42 are all directed downwardly.  
  Air exhaust ports 40 tsee FIG. 2) are configured as a plurality of preferably equi-angularly spaced sector shaped apertures surrounding the hole 39. In view of the streamlined oval shape of base 30. air intake ports 42 are preferably provided in a pair of separate sets. generally designated by reference numeral sets. 42a and 42&#34;. at the front and rear of the base 30. In accor dance with the broader aspects of the invention. the sets of ports 40 and 42 could be arranged concentrically in the base l5 where the cylindrical rather than the streamlined power unit configuration is preferred Screens 44a and 44h may be respectively provided over the air intake ports 42 for further assuring against the intake of debris.  
  For cutting off direct communication between air in take ports 42 and exhaust ports 40. the base 15 is provided with a pair of webs 46a and 46h upstanding from the bottom wall 30 and extending between opposite sidewalls 32. Webs 46a and 46/) respectively separate the aperture sets 42a and 42h from the ports 40. As will further be understood as the discussion proceeds. tipstanding baffle plates 48a and 48/: (see FIG. 5). bolted to webs 46a and 46h respectively. provide means for directing air vertically upwardly for increased contact with speed control components 2|. The components 2| are conveniently mounted on the outer face of these plates and thus are assured of receiving full cooling air flow on the first pass (see FIG. 5).  
  As shown in FIG. 5. the baffle plates 48:! and 4811. just described. stop short of the top of cover 26 and thus leave spaces 50:! and 50/1 for the turning or transfer of the air flow into the motor at apertures 62. Thus. for this streamlined oval design. the upward air flow channel 52 is divided by the baffle plates 48a and 48h into front and rear channels 52a. 52/) above aperture sets 42a and 42/) respectively. and an additional cham- (ill her 51 is actually formed between baffle plates 48a and 48b and the motor housing 54 as shown.  
  With reference to FIGS. 2. 3 and 5. the motor I4. which includes a cylindrical housing 54 and has the coaxial output shaft 16, is mounted vertically in the center of the power unit housing. A radially bladed centrifugal fan 56 is fixedly keyed to the motor output shaft I6 for pulling air vertically through motor I4 within annular space 87 between the rotor 88 and stator 89 (FIG. 6). which thus forms the second pass of the airv As will now be apparent. the provision of air directing means. comprising the webs 46 and flange 78 and the end bell housing (presently to be described in detail). enables vertical cooling air flow upwardly through the housing 26 and then downwardly through the motor I4 as established by the fan 56 and the exhaust in turned and directed through the ports 40, as shown in FIG. 5. It is because the intake ports 42 are also provided in the base of power unit 12, the air has first passed through the chambers 52a. 52b where electrical components 21a. 21b. are assured of being cooled completely. Since the motor I4 is run most of the time in forward rather than in reverse the blades of fan 56 may be configured to be more efficient in the forward direc tion.  
  Referring to FIG. 2. the motor housing 54 includes top and bottom bell housings 58 and 60 which respec tively have radial intake and exhaust orifices 62 and 64. The bell housings 58 and 60 are secured preferably by four anchor rods 68 extending vertically between two groups of four ears 70 and 7l carried by each of the top and bottom bell housings 58 and 60. Ears 70 and 7|. which radially extend front cylindrical portions 72 and 79. respectively. are preferably equi-angularly spaced about the cylindrical portions. The rods 68 preferably have one end threaded into the ears 7]. Bolts 73 pass through apertures 75 in the base I5 and threadably engage the feet 82 on bottont ofears 71 front underneath. The opposite end of the rods 68 pass through a hole in each ear 7] and are thread-ably engaged by nuts on top ofeach car H and again threadably engaged by nuts 74 on top of the cover 26. In this manner. all the major parts of the motor assembly I4 are securely attached together by the four rods 63. and the cover 26 is also secured. The cover may be removed from the power unit by removing nuts 24 and the motor may then be removed as a unit by simply removing the separate bolts 73.  
  The end bell housing 60 comprises a generally rectangular flange 78 extending from the bottom of cylindrical portion 79. The flange serves as a baffle fitting at its margins against the webs 46a and 46b and the sides 32 ofthe base I5. thereby forming a shroud to isolate the exhaust air being blown through the ports 40. The ears 7] (see FIG. 3) are sufficiently radially spaced outward from the periphery of the fan 56 to prevent any siren like wind noise from developing.  
  The fan 56 positioned on the shaft I6 is axially aligned with the generally annular orifice 64 defined between the flange 78 and a lower circular baffle structure 80 (see FIG. 3). The underside of structure 80 (FIG. 3) includes spaced support feet 82 and a central circular boss 84 containing a bushing 86 for the shaft 16. Circular structure 80 is of such a diameter that the exhaust ports 40 extend both radially outward and inward from the periphery thereof. In this manner. the ports 40 may be made of full size to accommodate the required air flow. Flow back under the structure 80 and through annular opening 81 in the end bell housing 60 (FIG. 3) is important to this feature. The structure 80 not only defines the final 90 turn in the tortous path of the exhaust air flow (FIG. 5), but also actually forms a mechanical baffle means, both of which conditions advantageously resist entry of water that might be inadvertantly splashed up from below.  
  With reference to H65. 2 and 5. particularly. speed control components 2|. including SCR control Zla. the details of which does not form a part of the invention per se. but may be of a conventional type. such as General Electric Model 50 having frequency controllable pulse oscillator and solid state modulating or chopping elements. may be provided. The control 2111 is advantageously cooled on the first pass of the air through the chamber 521: and likewise contactors 21h. 211&#39; are cooled on the first pass of air through the chamber 52b. The air is next transferred through the inner spaces 50a. 5011. and finally passes through orifices 62 and down through the annular gap 87 (see FIG. 6) between the rotor 88 and stators 89 for the main cooling operation.  
  The motor control circuitry includes the battery 20. four groups of leads )0. 92. 94. 96 interconnecting the components and the motor [4 in any conventional way such that a supply voltage is applied. The circuitry pulses the voltage for a fixed period of time. such as 3 milliseconds with a controllable repetition rate responsive to the potentiometer and control switches operated by the twist grip 22.  
  In the operation of the inventive cooling system. as best depicted in FIG. 5. the centrifugal fan 56 creates a circulating double pass air flow path. Air passes vertically upward into the power unit 12 through the screened intake ports 42. over the components 21 within the chamber 52 to cool the same. horizontally over the top of the baffle plates 48a. 48b. through the transfer spaces 5|). radially into the orifices 62. vertically downward through the annular gap 87 within the motor H to cool both the rotor 88 and the stator 89. radially outward through the centrifugal fan 56 and annular orifices 64 and turning downwardly and out of the power unit l2 via exhaust ports 40. It should be noted that the double pass air flow allows absorbtion of heat from the components 2|. as well as radiated heat from the motor H in chamber 52. Then. there occurs direct heat transfer in chamber Sl as the air circulates around the motor 14 b v convection and it finally passes through the gap 87 within the motor [4 for maximum cooling efficiency. Because of the double path flow. a tortuous path is presented for air entering the assembly so that any moisture droplets that might be sucked into the flow. tend to be removed by attachment to an inside wall of the housing prior to reaching the motor 14.  
  Having thus described a preferred embodiment ofthe present invention and its operation. it should be appar eat that numerous modifications might be made to the preferred embodiment within the spirit and scope of the present invention. For example. as mentioned briefly above. though not aesthetically desirable because not streamlined. the housing 26 of the power unit may be provided in a cylindrical configuration and the exhaust air confining means around the end bell housing 60 that is formed by the webs 46a. 46b and the sides 32 of the illustrated embodiment may be one circular wall with the intake ports then extending around the full periphery of that wall. Also. the baflle plates 48a. 48b and their equivalent in the circular configuration may be omitted. thus allowing the first pass of air to more effectively cool the motor by direct contact with the outside of the motor housing 54. Furthermore. the principles ofthe invention are quite applicable utilizing a propeller or axial fan in place of the centrifugal fan 56. thus exhausting the air axially directly through holes provided in the end bell housing and base [5. Therefore. it is intended that the description and drawing ofthe preferred embodiment be considered as illustrative of the concept of the invention and not in a limiting sense.  
 What is claimed is:  
  l. in an electrical outboard motor apparatus including a propeller drive means. an air cooled power unit apparatus drivingly positioned above said drive means including an electric motor vertically oriented within a housing. and said motor with an output shaft in driving relationship to said propeller means. wherein the im provement comprises: a set of air port means for intake in the bottotn wall of said housing and another set of air port means for exhaust in the bottom wall of said housing; upper and lower orifice means in said motor permitting air flow through said motor; said lower orifice means in communication with one of said sets of air port means. the other of said sets of air port means being located in the bottom wall of the chamber formed by the inside walls of said housing and the outside walls of said motor: said upper orifice means being in communication with said chamber; a fan mounted upon and driven by the shaft of said motor causing forced air circulation through said air port means. said orifice means. said motor. and said chamber. thereby providing dual pass cooling air flow. and ancillary speed control components necessary for controlling said electric motor mounted within said chamber where said speed control components are cooled by said forced air circulation.  
  2. The apparatus in claim 1 wherein said fan is a centrifugal fan and said exhaust orifice means is annular. said motor having top and bottom end bell housings. said exhaust port means being located at the bottom of said housing to receive the exhaust air from said exhaust orifice means formed in said bottom end bell housing.  
  3. The apparatus of claim 2 wherein said bottom end bell housing includes support ear means spaced radially outward from said fan and spaced horizontal baffle plates supported between said ear means forming said annular exhaust orifice means.  
  4. The apparatus ofclaim 3 wherein said exhaust port means extend radially inward beneath said horizontal baffle plates whereby maximum air flow and tortuous path isolation may be obtained.  
  5. The apparatus of claim 4 wherein is provided mounting rods passing through said power unit housing and interconnecting to the end bell housings of said motor and to said cover portion.  
  6. The apparatus of claim l wherein directing means is provided in the form of baffle means extending vertically upward from the bottom of said housing and positioned between said intake and exhaust port means. whereby increased air flow over said speed control components is obtained.  
  7. The apparatus in claim 6 wherein said speed control components are mounted on said baffle means.