Abstract:
A force coupling transfer device for use in marine equipment, snowmobiles, boats, automobiles, machinery, aircraft, recreational vehicles and other industries. The force coupling transfer device allows linear or rotational forces to be transferred from an input device to a controlled device. The force coupling transfer device includes an elongated flexible outer sheath and a movable flexible inner spring member. The inner spring member substantially transfers forces between two remote points located in a control space. The elongated flexible outer sheath is preferably a coiled spring and allows lubricating materials to pass through the surface to lubricate the inner spring member. A strain relief device, which may be a coiled spring, is preferably positioned around the outer sheath, adjacent to its ends, to prevent excessive bending of the outer sheath.

Description:
FIELD OF THE INVENTION 
     This invention relates to controllers or power transfer devices of the type that include a movable cable or element traveling inside a conduit. More specifically this invention relates to a force coupling transfer device that allows linear or rotational forces to be transferred between an input device and a controlled device. 
     BACKGROUND OF THE INVENTION 
     Control and power transmission technology is important to consumers and industry. These devices are used in a variety of applications from aircraft, automotive, marine, snowmobiles, machine control, and home appliance markets. This technology involves controlling the movement of parts or devices when linear or rotational force is transferred from one end of an elongated element to the other end. For example, this technology is generally directed to transfer forces from an input device, such as a lever or control pedal, to a controlled device, such as a motor controller, brake, clutch, or accelerator. 
     Control devices of this type generally have an elongated guide conduit and an elongated core element such as a cable made from woven metal strands, or a solid wire that moves inside of the guide conduit. These control devices may be susceptible to premature wear between the movable core element and the interior surface of the guide conduit because of ineffective lubrication. Further, lubricating an inner movable core element while inside the guide conduit can be difficult or impossible as the guide conduit surface construction that does not usually allow lubricating materials to pass therethrough. Coatings such as tetrafluoro polyethylene (Telfon) have been used as an inner tube liner to minimize the effects of friction and wear. However, this solution may be undesirable in some applications because it can be expensive and deteriorates over time. 
     In addition, some movable core elements, especially cables, tend to kink inside the guide conduit in response to inadvertent flexing. Kinking is undesirable for dependable operations and can lead to improper force transfer from the input device to the controlled device, and premature concentrated stress failure at the kink. 
     Thus with a woven cable, the inner cable begins to fail with the break of one strand at a kink. If a solid core is used, it begins to fail as a concentrated stress cracks the outer surface and it works its way through the cable for complete failure. Thus, even a seemingly minor kink or crack with the prior art can result in total failure. 
     Additionally, a shock load on a woven or solid core cable can also start, propagate, or complete failure because the cable has no ability to give without losing strength to withstand the load. 
     Still other force transfer devices in the art do not allow convenient, flexible routing through a control space, thus increasing cost to design additional parts. Existing devices also have additional drawbacks in power transmission because some installations of such controls require the conduit and movable core element to be bent in sharp angles which can cause excessive binding and kinking of the inner core element. Thus, a force transfer device minimizing and overcoming these and other drawbacks was needed. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, the present invention is directed to an improved force coupling transfer device for transferring linear and/or rotational forces that overcomes the aforementioned drawbacks in the conventional control technology. 
     An object of the invention is to substantially eliminate the kinking associated with existing technology. Kinking is reduced by utilizing an elongated flexible inner coiled spring positioned inside of an elongated flexible outer sheath that is supported at each end. 
     Yet another object of the invention is to substantially reduce a portion of the operational cost associated with mechanical actuator control devices in a machinery control environment. Due to the present invention, the elongated flexible outer sheath has the ability to allow lubricating liquids to pass through the outer surface to lubricate the inner coiled spring. This reduces wear between the inner coiled spring and the outer sheath. This advantage can save replacement and maintenance costs associated with labor, materials, and machinery equipment downtime. 
     These and other objects are achieved by the present invention, which according to one aspect, provides a force coupling transfer device for transferring a force that includes an elongated flexible outer sheath that has a center axis, and an elongated flexible inner coiled spring positioned inside of the outer sheath for movement. The inner coiled spring has an opposing first and second ends and transfers a force applied to the first end to the second end. The inner coiled spring also has a center axis. The outer sheath is permeable along its length to permit lubrication of the inner coiled spring. 
     In addition, the inner coiled spring sheath reduces the initial shock load from a force in either a pull or rotational operation which will reduce the failure potential of a rigid inner connector. The inner coiled spring activates the controlled equipment in a push or pull operation. Initial shock load on the coiled spring in the pull mode is relieved by a slight elongation of the inner coiled spring at the beginning of pull actuation. 
     Another object of the invention is to reduce the strain on the elongated flexible outer sheath. One aspect of the present invention provides at least one strain relief device disposed around the outer sheath. The strain relief device reduces strain on the ends of the outer sheath where the outer sheath is most likely to be damaged. 
     Another object of the invention is to control the operation of a device at a remote location to allow a human operator to perform multiple tasks in a manufacturing environment. This aspect to the invention provides for a force transfer system for use in machinery or equipment that has an input device, a controlled device, an elongated flexible outer conduit having opposing ends and an elongated flexible inner spring disposed inside of the outer conduit for movement. The inner spring also has first and second ends. The input device connects to the first end and the controlled device connects to the second end of the spring. The inner spring provides a force to the controlled device in response to force at the input device. 
     These and other objects and features of the invention will be apparent upon consideration of the following detailed description thereof, presented in connection with the following drawings in which like reference numerals identify the elements throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the force transfer device preferred embodiment of the present invention with the input device and the controlled device attached to opposing ends of the elongated inner coiled spring; 
     FIG. 2 is an isometric view of one end of the force transfer device; 
     FIG. 3 is a side view of one end of the force transfer device showing a strain relief device in an assembled position attached to a support bracket; and 
     FIG. 4 is an isometric view of the other end of the force transfer device coupled to a controlled device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-4, show a preferred embodiment of the present invention generally referred to as a force coupling transfer device  1  that functions to control the operation of a motor or engine upon the application of a force to an input device  18 , such as a control pedal. The force coupling transfer device  1  substantially transfers an axial force generated from an input device  18  to a controlled device  30 . An elongated inner coiled spring  4  is disposed inside of an outer sheath  2  for movement in response to a force. While the preferred embodiment transfers a linear force (e.g., push or pull), the force coupling transfer device  1  also has the capability to transfer a rotational force from the input device  18  to a controlled device  30 . 
     Referring to FIG. 1, an elongated inner coiled spring  4  is located inside of an elongated flexible outer sheath  2 . The outer sheath  2  is preferably also a coiled spring. Alternatively, the outer sheath  2  can be a flexible tubular conduit in lieu of a coiled spring. The outer sheath  2  is connected at its ends to a lower support bracket  20  and an upper support bracket  22 . The lower  20  and upper  22  support brackets are typically disposed at or adjacent to the input device  18  and the controlled device  30 , respectively, and are preferably fixed relative to the movable inner coiled spring  4 . The inner coiled spring  4  has a lower end  24  and an upper end  26 . The lower end  24  is preferably coupled to the input device  18  and the upper end  26  is preferably coupled to the controlled device  30 . 
     Referring to the lower portion of the force coupling transfer device  1 , as shown in FIGS. 1-3, the input device  18  is preferably connected to the lower end  24  of the elongated inner coiled spring  4  so that movement of the input device  18  causes the inner coiled spring  4  to move. The lower end  24  of the inner coiled spring  4  preferably has a connecting loop  25  formed from the wire of the inner coiled spring  4 . 
     The connecting loop  25  of the inner coiled spring  4  is preferably coupled to the input device  18  by standard fastening hardware, not shown, such as screws, or bolts and nuts. Other fastening techniques for attaching the elements together may be employed. The connecting loop  25  may be in the shape of a circle. As shown in FIG. 2, the connecting loop  25  is preferably located on an extension of the elongated inner coiled spring  4 , in which the extension is generally parallel to the center axis of the elongated inner coiled spring  4 . However, the connecting loop  25  can be of any orientation or shape to interface with the input device  18 . 
     The lower support bracket  20  provides a supporting structure for the elongated flexible outer sheath  2  and a strain relief device  14 . The lower support bracket  20  can be part of or attached to a larger structure, such as the device to be controlled like a sewing machine control platform (not shown) or an automobile floor board or dash board (not shown). The lower support bracket  20  includes a hole  21  to facilitate the alignment and the coupling of the outer sheath  2  and the strain relief device  14  to each other and to the support bracket  20 . A supporting structure other than a support bracket as shown may be employed. 
     The outer sheath  2  is preferably connected to the lower support bracket  20  so that the outer sheath  2  remains relatively stationary to allow movement of the inner coiled spring  4 . When the outer sheath  2  is a coiled spring, the end  7  preferably includes a connecting loop  6  formed from the wire of the coiled spring. 
     FIGS. 2-3 show the connecting loop  6  protruding from the outer sheath  2  in a direction substantially perpendicular to the center axis of the outer sheath  2 . In addition, the connecting loop  6  is preferably fastened to the lower support bracket  20  by hardware, such as a bolt  8 , and a washer  12 , and nut  10 . The bolt  8  extends through the connecting loop  6  and hole  21  of the lower support bracket  20  in which the washer  12  and nut  10  are coupled to the bolt  8 . 
     As best shown in FIG. 3, a strain relief device  14  is disposed around the outer sheath  2  to provide additional support, when needed, to reduce the stresses and strains on the end  7  and the connecting loop  6  of the outer sheath  2 . The strain relief device  14  also protects the outer sheath  2  and the inner spring  4  from being excessively bumped or bent from undesirable forces at their lower end. Also device  14  protects the lower end  7  of the outer sheath  2  and the lower end  24  of the inner spring. Preferably, it extends approximately two inches in length to protect the most vulnerable location of the outer sheath  2  and the inner spring  4 . The stresses and strains occur when the outer sheath  2 , produces a bending moment near the connection of the lower support bracket  20  or the upper support bracket  22 . The strain relief device  14  reduces the amount of stress and strain on the outer sheath  2  by providing a small counterbalancing bending moment at the appropriate location. The strain relief device  14  is preferably a coiled spring that has an end in the form of a connecting loop  16  formed integrally from the wire of the spring. The connection loop  16  of the strain relief device  14  protrudes away from the center longitudinal axis  40  of the strain relief device  14  such that a horizontal plane of the loop  16  is generally perpendicular to the center longitudinal axis  40 . 
     Referring to FIGS. 2-3, the fastening hardware that connects the elongated flexible outer sheath  2  to the lower support bracket  20 , also couples the strain relief device  14  to the lower support bracket  20 . The bolt  8  extends through the connecting loop  6  of the outer sheath  2 , the hole  21  in the bracket  20 , and the connecting loop  16  of the strain relief device  14 , and is attached on the other side of the bracket by washer  12  and nut  10 . The bolt  8 , washer  12 , and nut  10  configuration serves a dual purpose of coupling both the outer sheath  2  and strain relief device  14  to each other and to the lower support bracket  20 . The outer sheath  2  is further protected from strain as it penetrates hole  29  by the inside wall of the hole  29 . This design reduces material, assembly costs and provides faster assembly of the force coupling transfer device  1 . Although this configuration is preferable, other connecting and supporting structures could be employed. 
     Referring to FIGS. 1 and 3, the elongated flexible outer sheath  2  preferably includes a center longitudinal axis  42  running throughout the length of the outer sheath  2 . Similarly, the elongated inner coiled spring  4  includes an individual center longitudinal axis  44 . Also, the strain relief device  14  preferably includes a center longitudinal axis  40 . As shown in FIG. 3, the center longitudinal axis  40 ,  42 ,  44  are generally co-incident in the vicinity of the lower support bracket  20 . As shown in FIG. 4, the center longitudinal axis  42 ,  44  are also generally co-incident near the upper support bracket  22 . 
     Referring to the upper portion of the force coupling transfer device  1 , as can be seen from FIGS. 1 and 4, the upper end  26  of the elongated inner coiled spring  4  is connected to the controlled device  30  so that movement of input device  18  causes movement of the controlled device  30 . The controlled device  30  is coupled to motor or engine element  50 . Similar to the lower end  24 , the upper end  26  of the inner coiled spring  4  includes a connecting loop  27  in the form of a circle. The connecting loop  27  is preferably coupled to the controlled device  30  by fastening hardware such as a machine bolt  28 , and a nut  10 . As shown in FIG. 4, the connecting loop  27  is preferably located on an extension of the inner coiled spring  4 , in which the extension is generally parallel to the center longitudinal axis  44  of the inner coiled spring  4 . As shown in FIG. 4, the center axis of loop  27  is perpendicular to longitudinal axis  44  of the inner coiled spring  4 . 
     Similarly in the case of the lower support bracket  20 , the elongated flexible outer sheath  2  is preferably connected to the upper support bracket  22  so that the outer sheath  2  remains stationary to allow movement of the elongated inner coiled spring  4 . When the outer sheath  2  is a coiled spring as shown, the upper end  5  preferably includes a connecting loop  3  formed from the wire of the coiled spring. The connecting loop  3  is preferably fastened to the upper support bracket  22  by fastening devices such as a bolt  8 , and washer (not shown), and nut  10 . The bolt  8 , extends through the connecting loop  3  of the outer sheath  2  and is affixed by a washer and nut  10  to thereby couple the outer sheath  2  to the upper support bracket  22 . In an alternative embodiment, the outer sheath  2  may extend through the hole  39  in the upper support bracket  22 , similar to its arrangement relative to the lower support bracket  20 , so that the connecting loop  6  is on the side of the bracket  22  opposite from the body of the sheath  2 . 
     The upper support bracket  22  provides a supporting structure for the elongated flexible outer sheath  2  so that the outer sheath  2  remains relatively fixed in relation to the elongated inner coiled spring  4 . The upper support bracket  22  includes a hole  23  to facilitate the connection of the outer sheath  2  to the support bracket  22 . The upper support bracket  22  is preferably fastened to a larger structure, such as the motor controller for a sewing machine, automobile floor or dashboard, or other motor or engine controlled device (not shown). It is recognized that the support bracket  22  may take other forms from what is shown and it is used primarily to maintain the outer sheath  2  in a fixed position. 
     If desired, a strain relief device can be employed at the interface between the upper support bracket  22  and the outer sheath  2  in the vicinity of the end  5  similar to strain relief device  14  at the lower end  7 . While not shown in the Figures, a strain relief device such as shown in FIG. 3 may be used at the upper end  5  of outer sheath  2  and coupled to the bracket  22  in a similar manner. If a strain relief device is used, it can be fastened to the upper support bracket  22  by hardware similar to what is shown in FIG. 3 for the lower end  7 . 
     The outer sheath  2  preferably is an elongated tubular coiled spring. The outer sheath  2  is permeable throughout its length such that when the windings are slightly extended or opened, liquids such as lubricants, can pass through the elongated flexible outer sheath  2  to the elongated inner coiled spring  4 . In such an arrangement, the outer sheath  2  is preferably constructed from stainless steel to provide high durability, corrosion resistance, and tensile strength for corrosive and high load duty cycle environments. When the windings are in substantial contact, the lubricant is primarily retained inside of the outer sheath  2  and between the outer sheath  2  and inner coiled spring  4 . If desired, the outer sheath  2  can be composed of a flexible metal tube, or a polymer material in the shape of a tube that has holes or slots that allow the outer sheath  2  to be permeable. This alternative design would allow the lubricant to pass through the holes or slots in outer sheath  2  in a non-spring design or the inner spring  4  can be filled with a lubricant to lubricate between inner spring  4  and outer sheath  2  from the inside outward. 
     The elongated inner coiled spring  4  is preferably also tubular and also constructed from stainless steel. However, other materials may be utilized instead of stainless steel for the inner coiled spring  4 . The strain relief device  14  is also preferably a tubular coiled spring and is also composed of stainless steel. Other materials and constructions, however, may be employed for the strain relief device  14  in lieu of a coiled stainless steel spring. 
     Operating the system provides an effective method of transferring a force and associated motion. One such way the force coupling transfer device  1  can function is when a force generated by the input device  18  is transferred to the controlled device  30 . The controlled device  30  can be coupled to a motor or engine controller  50  that stops, starts, or controls the speed of various types of automobile engines or other engines or motors for machinery such as a sewing machine. The input device  18 , such as a foot or control pedal, is coupled to the lower end  24  of the inner coiled spring  4 , via connecting loop  25 , and the controlled device  30  attaches to the upper end  26  of the inner coiled spring  4  via connecting loop  27 . In this situation, the force coupling transfer device  1  can be used to operate machinery or engine when a human operator energizes the input device  18 . The controlled action on the input device  18  by an operator initiates a downward axial or linear force that pulls the lower end  24  of the inner coiled spring  4 . As the elongated flexible outer sheath  2  is fixed relative to the inner coiled spring  4 , the spring  4  will move downward and with respect to the outer sheath  2  in response to the axial force and substantially the same axial force pulls down on the upper end  26  of the inner coiled spring  4 . Thus, this same downward force is transferred to the controlled device  30 . 
     Likewise, if desired, a force on the input device  18  in the opposite direction creates an upward axial or linear force thereby pushing the lower end  24  of the elongated inner coiled spring  4  upward to substantially transfer the force to the upper end  26  of the elongated inner coiled spring  4 . 
     The operating system, if desired, can be used with an input device  18  and a controlled device  30  that are rotatable about the center longitudinal axis  44  of inner spring  4 . Under such an arrangement, a rotational force generated from the input device  18  is transferred to the controlled device  30 . The input device  18 , such as a crank, connects to the lower end  24  and the controlled device  30  connects to the upper end  26  of the elongated inner coiled spring  4 . The connecting loops  25  and  27  can be adapted to accept the input device  18  and the controlled device  30 , respectively. The action of the input device  18  causes a clockwise or counter clock rotational force at the lower end  24  of the inner spring  4 . The same rotational force is substantially transferred to the upper end  26  and the controlled device  30  in two simultaneous operations. Depending on the application, the rotational force can be transferred in both push or pull control situations. 
     Any non-negligible possible loss of force in a linear or rotation force transfer can be mitigated or eliminated by reducing the frictional contact of the surfaces. The frictional contact may be reduced by lubricating the exterior surface of the inner coiled spring  4  and the interior surface of the outer sheath  2 . When the outer sheath  2  is a coiled spring, the windings can be slightly extended or stretched to allow lubricant to pass to the elongated inner coiled spring  4 . Alternatively, the lubricant may be injected inside of the inner coiled spring  4  to allow the lubricant to flow into the outer sheath  2 . 
     In addition, the coupling location of the input device  18  and the controlled device  30  can be interchanged as this device works without regard to orientation. The input device  18  can be coupled to the connecting loop  27  at the upper end  26  of the inner coiled spring  4 . Also, the controlled device  30  can be coupled to the connecting loop  25  at the lower end  24  of the inner coiled spring  4 . 
     If desired, device  1  can operate without a strain relief device  14  so that the elongated flexible outer sheath  2  remains exposed throughout its entire length. In addition, the lower end  24  and upper end  26  of the inner coiled spring  4  can be exposed. 
     Additionally, the present invention may be used to couple two input devices together. Such an arrangement may be advantageous in certain circumstances. Such an arrangement can facilitate switching of operators or limbs by a single operator. Thus, for example, by coupling two input foot pedals together, the operator may switch feet during the operation of a device such as an automobile or sewing machine. Alternatively, the pedals may be accessible by multiple users so that switching of operators may be done without changing the operation of the motor being used. It is recognized that in some circumstances, it may be beneficial or necessary to route the device in a certain direction or orientation based on whether pulling or pushing operations are required. 
     While this particular embodiment of the invention has been shown and described, it is recognized the various modifications thereof will occur to those skilled in the art. Therefore, the scope of the herein-described invention shall be limited solely by the claims appended hereto.