Abstract:
A wrap spring device includes a first hub and a second hub located axially to the first hub. A wrap spring is located externally and concentrically about the first and second hubs and glycol-based solution surrounds the spring. The spring is engaged and disengaged thereby causing the first and second hubs to engage and disengage each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 61/007,760 entitled “IMMERSED WRAP SPRING DEVICE,” having a filing date of Dec. 14, 2007, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to a wrap spring device, and in particular, a wrap spring device that is immersed in a water-based solution. Wrap spring devices allow variable connection between an input and an output with the control of the wrap spring. For example, the wrap spring can be controlled to alternatively allow it to wrap down onto input and output hubs and to allow it to wrap open off of the input or output hub. 
         [0003]    In some designs, an oil or grease-based material is used in or around the wrap spring device to better dissipate heat and provide lubricity. However, some applications needing this additional cooling and lubricity cannot use these oil or grease-based materials. Furthermore, existing devices are not configured to operate properly in water or glycol-based liquids that could provide said cooling and lubricity. For these and other reasons, a need exists for the present invention. 
       SUMMARY 
       [0004]    One embodiment provides a wrap spring device including a first hub and a second hub located axially to the first hub. A wrap spring is located externally and concentrically about the first and second hubs and a glycol-based solution surrounds the spring. The spring is engaged and disengaged thereby causing the first and second hubs to engage and disengage each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
           [0006]      FIG. 1  illustrates a perspective view of one embodiment of a wrap spring device immersed in water. 
           [0007]      FIG. 2  illustrates an exploded view of the wrap spring device illustrated in  FIG. 1 . 
           [0008]      FIG. 3  illustrates a sectional view of the wrap spring device illustrated in  FIG. 1 . 
           [0009]      FIG. 4  illustrates a perspective view of another embodiment of a wrap spring device immersed in water. 
           [0010]      FIG. 5  illustrates an exploded view of the wrap spring device illustrated in  FIG. 4 . 
           [0011]      FIG. 6  illustrates a sectional view of the wrap spring device illustrated in  FIG. 4 . 
           [0012]      FIG. 7  illustrates a perspective view of another embodiment of a wrap spring device immersed in water. 
           [0013]      FIG. 8  illustrates an exploded view of the wrap spring device illustrated in  FIG. 7 . 
           [0014]      FIG. 9  illustrates a sectional view of the wrap spring device illustrated in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
         [0016]      FIGS. 1-3  respectively illustrate perspective, exploded and sectional views of wrap spring device  10  in accordance with one embodiment. These figures illustrate one embodiment of the invention. In  FIGS. 1-3 , wrap spring device  10  includes shaft  12 , hub  14 , collar  16 , actuator  18  and wrap spring  20  with spring toe  22 . In the figure, wrap spring device  10  is illustrated immersed in water outlined with a dashed line. Wrap spring device  10  allow variable connection between shaft  12  and hub  14  with the control of wrap spring  20 , and it is configured to operate while fully immersed in water. 
         [0017]    In one embodiment, hub  14  is free to rotate on shaft  12 . Shaft  12  is pressed into collar  16  and holds collar  16  concentrically and axially located with respect to hub  14 . Spring  20  is located concentrically with hub  14  and collar  16 . When fully assembled, spring  16  has an interference fit with collar  16 , and the interference fit can be achieved in a variety of ways. 
         [0018]    When in an equilibrium state, spring  20  also has an interference fit with hub  14 , which causes collar  16  to be solidly coupled to hub  14  the when collar  16  is driven in the clockwise direction (illustrated in  FIG. 1  with arrow  24 ). Spring  20  can be wound in either a left-hand or a right hand configuration to provide for the desired input direction. As indicated with arrow  24 , shaft  12  and collar  16  are configured to rotate in clockwise direction  24 . 
         [0019]    In one embodiment, actuator  18  can be moved in direction  26  toward and away from spring toe  22  on wrap spring  20 . In one example, when actuator  18  is moved such that it engages spring toe  22  while collar  16  is driven in clockwise direction  24 , wrap spring  20  will wrap off of collar  16 . As such, wrap spring device  10  will be released when actuator  18  is moved into an interference position with spring toe  22  of wrap spring  20 . 
         [0020]    In one embodiment, the entire wrap spring device  10  is immersed in a glycol-based solution, such as an antifreeze and water mixture. This area that contains the water solution surrounding wrap spring device  10  is illustrated by a dashed line. The remaining components can be either partially or fully immersed in the water solution. In one embodiment, the glycol-based solution surrounding wrap spring device may include water and additives thereto. The water and additives can aid in the cooling and lubricating of wrap spring device while it operates. 
         [0021]      FIG. 4-6  respectively illustrate perspective, exploded and sectional views of one embodiment of a wrap spring device  40 . In this embodiment, wrap spring device  40  includes shaft  42 , bearing  44 , seal  46 , housing  48  (including first and second halves  48   a  and  48   b ), control plate bushing  49 , control plate  50 , wear plate  52 , case  54 , coil  56 , coil connector  58 , tube  60 , collar  62 , spring  64 , spring toe  66 , hub  68 , impeller  70 , and retaining ring  72 . When assembled, wrap spring device  40  allows variable connection between shaft  42  and hub  68  with the control of wrap spring  64 , and it is configured to operate while fully immersed in a glycol-based solution. 
         [0022]    In one embodiment, hub  68  and impeller  70  are free to turn on shaft  42 . Collar  62  is press fit onto shaft  42 . Spring  64  then spans collar  62  and hub  68 , and spring  64  has an interference fit with hub  68 . The interference fit between spring  64  and hub  68  can be achieved in a variety of ways. In one example, hub  68  is configured with a slot into which spring toe  66  of spring  64  is press fit. When in an equilibrium state, spring  64  also has an interference fit with collar  62 , which causes collar  62  to be solidly coupled to hub  68  when control plate  50  is not engaged with wear plate  52 . 
         [0023]    When wrap spring  40  is fully assembled, control plate  50  is configured with a loose fit over spring  64  so that it can move axially. In one embodiment, control plate  50  has a notch configured to receive spring toe  66  so that it can support rotational torque. Control plate bushing  49  is configured to fit outside spring  64  and spring toe  66  and control plate  50  is configured to fit over control plate bushing  49 . 
         [0024]    Case  54 , coil  56 , tube  60  and wear plate  52  are all fixed to housing  48 . Coil  56  creates an electromagnetic field that flows through case  54  and tube  60  and creates a magnetic force that will attract control plate  50  against wear plate  52  when coil  56  is energized. Wear plate  52  is non-magnetic and is used to create a larger wear surface to extend the life of the device. 
         [0025]    When coil  56  is not powered, impeller  70  is coupled to shaft  42  by hub  68 , spring  64  and collar  62 . When coil  56  is powered, control plate  50  is held against wear plate  52  and this prevents the rotation of control plate  50 . Since control plate  50  receives spring toe  66  in a notch, control plate  50  prevents spring toe  66  of spring  64  from rotating while control plate  50  is prevented from rotation while coil  56  is energized. This causes spring  64 , hub  68  and impeller  70  to be decoupled from shaft  42 . 
         [0026]    In one embodiment, wrap spring device  40  is configured in a glycol-based solution or water-based solution. In one example, the glycol-based solution is a water and glycol solution within cooling system. The water solution may include any of a variety of a family of hydroxyethers. As such, when impeller  70  is rotating it pumps or circulates the water/glycol solution throughout the cooling system while wrap spring device  40  is engaged, and then stops circulating the water/glycol solution when wrap spring device  40  is disengaged. 
         [0027]    Housing  48  holds the components in the proper position and provides a container for the water/glycol mixture. In one case, housing  48  includes first and second halves  48   a  and  48   b,  which are bolted together with bolts or fasteners to form housing  48 . The water/glycol mixture is able to freely flow around the components of wrap spring device  40 , including spring  64 , control plate bushing  49 , and control plate  50 . Bearing  44  supports shaft  42  and seal  46  prevents water from leaking out of housing  48 . Retaining ring  72  holds impeller  70  and hub  68  in the proper axial position with respect to collar  62 . 
         [0028]    In one embodiment, the glycol-based or water-based solution surrounds all the components of wrap spring device  40  and is circulated throughout the system. In one example, the system is the cooling system of an automobile. In one embodiment, the water-based solution is a type of hydroxylether, such as water/glycol mixture. For example, ethylene glycol or propylene glycol can be mixed in water. These types of additives to water can increase the effective boiling point (“colligative agents”) of the solution and/or decrease the freezing point (“antifreeze agents”) of the solution. 
         [0029]    In addition, these additives to water can add lubrication to the system, which includes the various components of wrap spring device  40  that are contained within the water-based solution. As such, wear among the various interfering components of the wrap spring device can be decreased by the lubricious-material additives to the water. Also, where wrap spring device  40  changes suddenly from engaged to disengaged, that is, wrap spring  64  wraps open off of collar  62 , or visa versa, that is, wrap spring  64  wraps down on collar  62 , the surrounding water-based solution may help blunt the shock on the components, including wrap spring  64 , especially where shaft  42  is normally rotating at high RPM. 
         [0030]    Additional materials can be added to the water to inhibit corrosion within the system, which includes the various components of wrap spring device  40  that are contained within the water-based solution. These additives can be effective against corrosion, for example, where wrap spring device  40  has components that include a range of electrochemically incompatible metals such as aluminum, case iron, copper, steel and solder. 
         [0031]    In one embodiment, the water-based solution is circulated through wrap spring device  40  as illustrated by the arrows in  FIG. 6  (two within device  40  and two illustrating entry to and exit from device  40 ). When in operation, shaft  42  of wrap spring device  40  can rotate at very high RPM, for example, as high as 8,000 RPM. At these speeds, heat will be generated by the various parts of wrap spring device  40 , and the circulation of the water-based solution can help move that heat out of wrap spring device  40 . In addition, debris can be generated from the various parts of wrap spring device  40  interfering with each other over time. The circulation of the water-based solution through wrap spring device  40  can also help move the debris out if the device. 
         [0032]      FIGS. 7-9  respectively show perspective, exploded and sectional views of another embodiment of a wrap spring device  100 . Wrap spring device  100  includes shaft  102 , bearing  104 , seal  106 , housing  108 , shoulder  110 , control ring  112 , ring bushing  114 , brake collar  116 , case  118 , coil  120 , coil connector  122 , tube  124 , collar  126 , spring  128 , spring toe  130 , hub  132 , impeller  134 , and retaining ring  136 . 
         [0033]    Wrap spring device  100  illustrates a device that is similar to wrap spring device  40  illustrated in  FIGS. 4-6 . Wrap spring device  100 , however, includes a spring  128  that has clearance with collar  126  and electrical power is used to engage the device. When assembled, just like wrap spring device  40 , wrap spring device  100  allows variable connection between shaft  102  and hub  132  with the control of wrap spring  128 , and it is configured to operate while fully immersed in a glycol-based solution. 
         [0034]    Control ring  112  is located on ring bushing  114 , which is a non magnetic bushing, and is free to rotate and move axially with respect to shaft  102 . Spring  128  has an axial spring toe  130 , which fits into a slot on control ring  112 . Shoulder  110  is solidly connected to shaft  102 . When power to coil  120  is off, control ring  112 , spring  128 , hub  132  and impeller  134  are free to rotate with respect to shaft  102 . When coil  120  is energized, it creates an electromagnetic field that flows through case  108 , tube  124 , control ring  112  and shoulder  110 , which creates a magnetic force that will attract control ring  112  to shoulder  110 . This causes spring  128  to wrap down on collar  126 , which couples hub  132  and impeller  134  to collar  126  and shaft  102 . 
         [0035]    Brake collar  116  is an optional part that can be used to provide a braking force when power to coil  120  is off. Spring  128  has an interference fit with brake collar  116  in the free state with power off. This prevents hub  132  and impeller  134  from rotating in one direction because spring  128  will expand and couple hub  132  to brake collar  116 . This does not affect the engagement performance of this wrap spring device  100 , because spring  128  can easily pull away from brake collar  116  when power is applied to coil  120 . 
         [0036]    In operation, wrap spring device  100  is also surrounded by a water-based solution that is circulated throughout the system as indicated with the arrows in  FIG. 9  (two within device  100  and two illustrating entry to and exit from device  100 ). Wrap spring device  100  can also be configured in the cooling system of an automobile, and as above, water-based solutions can include a type of hydroxylether, such as water/glycol mixture, ethylene glycol or propylene glycol. As above, these solutions can adjust freezing and boiling points, add lubrication, reduce wear, shock, and corrosion and remove heat and debris. 
         [0037]    Although, the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. One skilled in the art will recognize that various other applications for the wrap spring device are possible consistent with the invention.