Patent Publication Number: US-6217355-B1

Title: Compressed air clockspring

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the transmission of electrical signals and compressed air through a rotary joint or connector. The invention more particularly concerns a rotary connector which takes the form of an automotive clockspring. 
     2. Discussion of the Background 
     Clocksprings are well known in the automobile industry. An automotive clockspring is an electrical connector or rotary transducer which electrically connects a rotatable airbag assembly mounted on the steering wheel to stationary crash sensors located elsewhere on the vehicle. An automotive clockspring typically includes a housing and a cover mounted to the housing so as to form a cavity therebetween. Rotatably mounted within the cavity is a hub. The clockspring housing is non-rotatably mounted to the steering column, while the hub is attached to the rotatable airbag assembly. A flat ribbon cable is wound around the hub. One end of the flat ribbon cable terminates at the stationary housing or cover and the other end terminates at the hub. The end of the flat ribbon cable terminated at the hub is then connected to an electrical cable which connects to the airbag assembly. During use, the flat ribbon cable is either spooled or un-spooled around the hub when the steering wheel is rotated in one direction or the other direction. Examples of clocksprings are provided in U.S. Pat. Nos. 5,785,541, 5,601,437, 5,580,259, 5,490,793, 5,487,667, 5,460,535, 5,429,517, 5,980,286, and 5,775,920 all of which are hereby incorporated herein by reference. 
     Devices other than airbags are also mounted on the steering wheel which receive electrical signals. As the automotive industry has matured, vehicles have become more refined as fueled by consumer requirements. Vehicles that appeal to the consumer-mass-market typically have controls and features which are within an arm&#39;s length of the driver. To reduce the amount of effort on the part of the driver and to increase the comfort of the driver, more and more functions, switches, and controls are placed ever closer to the driver. Since the driver&#39;s hands are on the steering wheel, automobile manufacturers have been placing electrical switches on the steering wheel so that the driver can activate the electrical switches with one finger while keeping their hands on the steering wheel. 
     Thus, there is a need for increasing the comfort of drivers of automobiles while the drivers keep their hands on the steering wheel. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a clockspring which can support controls and devices mounted on the steering wheel. 
     It is a further object of the invention to provide a clockspring which can support controls and devices mounted in the steering wheel. 
     It is yet another object of the invention to provide a clockspring which provides electrical energy to the steering wheel. 
     It is still yet another object of the invention to provide a clockspring or rotary connector which provides compressed air or pneumatic energy to the steering wheel. 
     It is another object of the invention to provide a device which is low in cost to produce. 
     It is still further another object of the invention to provide a clockspring which is highly reliable. 
     In one form of the invention the compressed air clockspring includes a housing, a hub, a ribbon cable, and an air ring. The housing has a first electrical connector and a first pneumatic port. The hub has a second electrical connector and a second pneumatic port. The hub is rotatably mounted to the housing. The ribbon cable has a first end and a second end. The first end of the electrical cable is attached to the first electrical connector of the housing, and the second end of the ribbon cable is attached to the second electrical connector of the hub. The air ring is rotatably mounted to the housing. The air ring fluidically connects the first pneumatic port of the housing to the second pneumatic port of the hub. 
     In yet another form of the invention, the compressed air clockspring includes a housing, a hub, electrical connection means, and fluidic connection means. The housing has a first electrical connector and a first pneumatic port. The hub has a second electrical connector and a second pneumatic port. The hub is rotatably mounted to the housing. The electrical connection means connects the first electrical connector to the second electrical connector. The fluidic connection means connects the first pneumatic port to the second pneumatic port. 
     In another embodiment, the compressed air clockspring is known as a rotary connector for transmitting compressed air since the device does not include a ribbon cable. The rotary connector includes a housing, a hub, and an air ring. The housing has a first pneumatic port. The hub has a second pneumatic port. The hub is rotatably mounted to the housing, and the hub having an axis of rotation. The air ring is rotatably mounted to the housing. The air ring fluidically connects the first pneumatic port of the housing to the second pneumatic port of the hub. The first pneumatic port being located a first distance away from the axis of rotation, and the second pneumatic port being located a second distance away from the axis of rotation. 
     Thus, the invention achieves the objectives set forth above. The invention provides a device which conveys both electrical and pneumatic energy through a rotary connector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is an exploded perspective view of the compressed air clockspring; 
     FIG. 2 is a side view of the assembled compressed air clockspring of FIG. 1; 
     FIG. 3 is a top view of the compressed air clockspring of FIG. 2; and 
     FIGS. 4 and 4A are cross-sectional views of the compressed air clockspring taken along section line  4 — 4  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1-4 thereof, an embodiment of the present invention is a compressed air clockspring  10  as shown in FIGS. 1-4. 
     FIG. 1 is an exploded top view of the compressed air clockspring  10 . The compressed air clockspring  10  includes a housing  12 , a hub  58  rotatably mounted in the housing  12 , and a cover  68  retaining the hub  58  within the housing  12 . The housing  12  includes an electrical connector  14 , an outer wall  18 , an inner wall  16 , locking features  19 , and multiple mounting bosses  20 ,  22 . The bottom of the housing  12  has a pneumatic port  24  (see FIG. 4) which is in fluidic communication with a recess  26 . In a preferred embodiment, insert-molded into a bottom of the housing  12  is a slip ring  28 . The slip ring  28  has numerous tangs  32  around which material of the housing  12  is insert-molded. The slip ring  28  may also be attached to the housing  12  via other means such as with fasteners or adhesives or compression fit with the recess  26 . The slip ring  28  also has a plurality of orifices  30 . The pneumatic port  24 , recess  26 , and the orifices  30  of the slip ring  28  are in fluidic communication with each other. 
     The cover  68  includes multiple locking latches  70  which are complementary to the locking features  19  of the housing  12  (as shown in FIG.  2 ). 
     The hub  58  includes an electrical connector  60 , an outer wall  62 , an aperture  63 , an inner wall  64 , and a pneumatic port  66 . When the hub  58  is rotatably mounted within the housing  12 , the resulting structure creates an inner annulus  74 , and an outer annulus  72 , as shown in FIG.  4 . The ribbon cable (not shown) is wound within the outer annulus  72 . The ribbon cable is typically a flat cable having multiple copper conductors enclosed within insulating layers. One end of the ribbon cable terminates at the electrical connector  14  of the housing  12 , and the other end of the ribbon cable terminates at the electrical connector  60  of the hub  58 . The ribbon cable is simply wound around the outer wall  62  of the hub  58  and either becomes further wound or unwound depending on the relative rotation between the hub  58  and the housing  12 . Held within the inner annulus  74  is an air ring  40  and springs  52 ,  54 ,  56 . 
     The air ring  40  includes a recess  41  (see FIG.  4 ), spring supports  42 ,  44 , and an air pipe  46 , an inner rim  50 , and an outer rim  51 . The air pipe  46  includes an aperture  48 . The aperture  48  is in fluidic communication with the recess  41 . Attached to the air ring  40  is a slip ring  34 . The slip ring  34  has a plurality of orifices  36 , and multiple tangs  38 . In a preferred embodiment, the material of the air ring  40  is insert-molded around the tangs  38  of the slip ring  34  so as to create an integral assembly. The spring supports  42 ,  44  and the air pipe  46  are surrounded by springs  52 ,  54 ,  56  in order to provide a tensile force between the housing  12  and the hub  58 , when the springs  52 ,  54 ,  56  are in a state of compression. Other tensile means known in the art may be used in place of the springs  52 ,  54 ,  56 . 
     As shown in FIGS. 1 and 3, the air ring  40  is retained in the radial direction by the inner wall  16  of the housing  12  and by the outer wall  62  of the hub  58 . Furthermore, the air ring  40  rotates in unison with the hub  58 , since the air pipe  46  of the air ring  40  extends through the pneumatic port  66  of the hub  58 . 
     During assembly, the springs  52 ,  54 ,  56  are slipped over the respective spring support  42 ,  44  and the air pipe  46 . Then the air ring  40  containing the springs  52 ,  54   56  are placed within the inner annulus  74  of the hub  58  so that air pipe  46  protrudes through the pneumatic port  66  of the hub  58 . The height of the springs  52 ,  54 ,  56 , in a free state, is greater than a height of the inner annulus  74 , thus, once assembled, the springs  52 ,  54 ,  56  are in a state of compression. The force generated by the compressed springs  52 ,  54 ,  56  urge the two slip rings  28 ,  34  towards each other so as to produce an effective seal at that location. One spring or more than three springs can be used to provide the sealing force. Three springs are shown since the combination of three springs prevents the air ring  40  and the hub  58  from being skewed by an unbalanced force. That is, the three springs each, individually, produce a force the sum of which results in a force which is nearly co-axial with the rotational axis of the hub  58 . The ribbon cable is then attached at one end with the electrical connector  14  of the housing  12  and the other end of the ribbon cable is then connected to the electrical connector  60  of the hub  58  with the remaining amount of the ribbon cable wound about the region of the outer annulus  72  of the hub  58  while the hub  58  is inserted into the housing  12 . Thereafater, the cover  68  is placed over the assembled parts and retains those parts within the housing  12 . 
     FIG. 2 shows the attachment of the locking latches  70  of the cover  68  with the complementary features of the locking features  19  of the housing  12 . FIG. 2 also shows the electrical connectors  14 ,  60 . Once the unit is assembled, the locking features  19  and the locking latches  70  can be welded together. Furthermore, during assembly grease is placed between the slip rings  28 ,  34 , so as to accommodate the relative rotation between the slip rings  28 ,  34 . 
     FIG. 3 is a top view of the compressed air clockspring  10 . FIG. 3 shows details of the mounting bosses  20 ,  22 , the air pipe  46 , the pneumatic port  66  of the hub  58 , electrical connector  60 , electrical connector  14 , and the aperture  63  of the hub  58 . 
     FIGS. 4 and 4A are cross-sectional views of the compressed air clockspring  10  taken along section line  4 — 4  of FIG.  3 . FIG. 4 shows the placement of a representative spring (such as spring  52 ) in the inner annulus  74 . For reasons of clarity the ribbon cable is not shown in the outer annulus  72 . FIG. 4 makes evident the fluidic communication between the pneumatic port  24  of the housing  12 , the recess  26  of the housing  12 , and the recess  41  of the air ring  40 . FIG. 4A is an enlarged view of the slips rings of FIG.  4 . 
     In operation, the electrical portion of the compressed air clockspring  10  operates similarly to clocksprings of previous designs that were mentioned previously and incorporated herein by reference and will not be discussed further. The compressed air portion of the compressed air clockspring  10  includes the introduction of compressed air into the pneumatic port  24  of the housing  12 . The compressed air then flows into the recess  26  of the housing  12 . From there the compressed air flows in the orifices  30  of the slip ring  28 . The compressed air then continues on to the orifices  36  of the slip ring  34 . Little or no compressed air escapes in the region between the slip rings  28 ,  34 , since the springs  52 ,  54 ,  56  are in a state of compression and urge the air ring  40  which contains the slip ring  38  toward the slip ring  28 . The compressed air is then introduced into the recess  41  of the air ring  40 . Then the compressed air is finally transmitted into the aperture  48  of the air pipe  46  of the air ring  40  and can then be transmitted to a device on the steering wheel. Since the air pipe  46  passes through the pneumatic port  66  of the hub  58 , the compressed air also passes through the pneumatic port  66 . However, the air ring  40  can be modified so that the air pipe  46  does not pass through the pneumatic port  66 . In such an embodiment, the air pipe  46  attaches to the pneumatic port  66  from within the inner annulus  74 . The orientation of the orifices  30 ,  36  ensure that there is a free flow of compressed air between the housing  12  and the air ring  40  depending on the size and number of the orifices  30 ,  36  regardless of the relative rotation of the hub  58  and the housing  12 . 
     In a preferred embodiment, the housing  12 , the hub  58 , the cover  68 , and the air ring  40  are preferably made of a polymer material. The springs  52 ,  54 , and  56  are typically made of a metallic compound. The slip rings  28 ,  34 , are preferably made of brass. 
     Thus, the device can supply warm air to the steering wheel so as to warm the hands of the driver, or the compressed air can be used to provide ventilation to the driver. Furthermore, the compressed air can be used for other purposes. 
     Furthermore, in another embodiment, the compressed air clockspring can be used without the ribbon cable. Such a device is a rotary connector for transmitting compressed air. The rotary connector for transmitting compressed air is not shown. 
     Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.