Abstract:
A device is added to or built into a subject large vehicle, such as a large motorhome. The device provides for the driver&#39;s use either one or two retracting steps to facilitate the driver&#39;s entrance into or exit from the subject vehicle. Since these steps retract for travel, they are able to extend far enough beyond the side of the subject vehicle to allow the driver&#39;s weight to be directly above each step in stair step fashion rather than vertical ladder fashion. The device makes motorhome driver&#39;s side doors safer and more usable for less athletic people and the elderly.

Description:
This application claims benefit of provisional application No. 60/852,347, filed Oct. 16, 2006. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a retractable step system which can be built into a large vehicle such as a motorhome or retrofitted later. Although the system can be operated manually, the preferred method is to have the deployment of the steps be automatic, triggered by the opening and closing of the driver&#39;s door. The design of the retractable steps provides a place for the driver to step which extends far enough beyond the body of the vehicle to allow the driver to bring his/her full weight directly over the step before moving to the next step or into the vehicle. The specific design of the device provides for control of the rate of movement and the force behind each movement to avoid injury to anyone or anything in the path of the subject movement. It also provides for a positive locking of each step in place to provide secure footing for any person using it. 
     The need for the subject invention comes from the fact that, in many large vehicles such as a Class A motorhome the floor in the driver&#39;s area is often 3½ feet or more above the ground. Also in many of these large vehicles the driver sits nearly over the front wheel. It is impractical to employ a retractable step of the type commonly used in the middle of the passenger side on many Class A motorhomes, since it would have to be installed where the front wheel is located. The present invention, due to its rotary action, can rotate out from either in front of or behind the front wheel to provide a step or steps where needed. Some attempts have been made to solve this problem by building in a set of fixed steps for the driver similar to the classic bus entrance steps. However, this has proven difficult due to the presence of both the front wheel and the driver&#39;s controls. As a result, those manufacturers who provide a driver&#39;s side door on Class A motorhomes, do so as a “safety” measure, not as a convenient way into and out of the vehicle. However, even as an “emergency” exit these doors are not really safe for use by any but the most athletic person. 
     Typically manufacturers of “Class A” motorhomes equipped with driver&#39;s side doors have provided various types of pocket steps built into the side of the motorhome or various types of stirrup steps mounted in the wheel well area. Coupled with these are various grab bars and hand grips. However, considerable athletic ability is needed to get in and out of the vehicle using these devices. The main problem with these steps and/or stirrups is that a person attempting to go into or out of the vehicle using them must depend on arm strength to support much of the person&#39;s weight. Many people using motorhomes are not capable of doing this easily and safely. The present invention eliminates most or all of this requirement for arm strength. Also, the previous types of step devices are often hard to locate with a foot and are very easy to miss when the person is exiting the vehicle. This has resulted in injuries. The present invention solves this problem because the step or steps are clearly visible and readily accessible to the person exiting the vehicle. 
     Prior art includes a large variety of stirrups, pocket steps, grab handles and grab bars both inside and outside various vehicles, including motorhomes. For example, U.S. Pat. Nos. 6,179,312 (Paschke et al.) and 6,264,222 (Johnston et al.), both of which use a vertical pivot but are not shaft mounted. They both require major body design modifications and are therefore not suitable for retrofit to existing vehicles. The present invention is readily adaptable to retrofit to existing vehicles and vehicle design. These two patented devices are also designed primarily for use on truck cabs rather than motorhomes. 
     A number of other existing patents utilize a rotary motion to extend and retract a step from beneath the body of a vehicle. For example, U.S. Pat. Nos. 4,231,583 (Learn), 3,980,319 (Kirkpatrick), 4,708,355 (Tiede) and 3,762,742 (Bucklen), teach a step rotating on an inclined axis to place the step low to the ground when extended and clear the body lower edge when retracted. This limits the size of the step to not much more than a stirrup. An important aspect of the present invention is the large size of the step or steps which allows the person using them to have their weight fully centered over each step. Tiede also uses electric motor actuation rather than the air cylinder actuation employed in the present invention. Yet another rotary step patent (U.S. Pat. No. 5,897,125, Bundy) is a small treadle manually deployed to provide access at the side of a pick up truck bed. 
     Other patents which employ the concept of a step rotating out from under the vehicle body about a vertical axis are U.S. Pat. Nos. 3,329,443 (Lowder et al.), 6,283,537 (DeVore), 6,659,484 (Knodle et al.) and 3,861,713 (McKee), all teach a rotational step which retracts beneath the vehicle body but none of them apply to the driver&#39;s side door as does the present invention. Additionally, U.S. Pat. No. 3,388,925 (Chavira et al.) teaches a vertical shaft mounted step assembly to provide access to a loading dock and therefore differs from the present invention which provides access to and from the driver&#39;s side door. 
     The following list of prior patents presents a variety of step mechanisms which do not meet the requirements for an automatically deployed step assembly providing comfortable access to and from the driver&#39;s side door of a large motorhome for people of limited athletic ability as the present invention does. U.S. Pat. Nos. 6,942,233 (Leitner et al.), 6,655,706 (Murrell), 5,687,813 (Bensch), 5,660,405 (Campbell), 5,456,479 (Conger), 5,342,073 (Poole), 5,284,349 (Bruns et al.), 5,224,723 (Hatas), 5,195,609 (Ham et al.), 5,150,659 (Bickel), 5,137,294 (Martin), 5,092,617 (Jones), 4,264,084 (Telles), 4,251,179 (Thorley), 4,217,971 (Rivinius), 4,200,303 (Kelly), 4,185,849 (Jaeger), 4,106,790 (Weiler), 3,912,298 (Humphrey), 3,833,240 (Weiler), 3,807,758 (Rogge), 3,756,622 (Pyle et al.), 3,743,320 (Clark) and 3,751,068 (Green). 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A to 1D  show views of a person entering a large vehicle, a motorhome.  FIGS. 1A and 1B , labeled “PRIOR ART”, show the degree of difficulty experienced by a person entering or exiting such a vehicle.  FIGS. 1C and 1D , labeled “Using present invention”, demonstrate the improvement using the present invention, a driver&#39;s side step in its simplest preferred embodiment. 
         FIG. 2  shows the present invention, a driver&#39;s side step in its simplest preferred embodiment, as seen from directly overhead. The step is shown in the “extended” or “open” position. 
         FIGS. 3A-3D  show the present invention, a driver&#39;s side step in another preferred embodiment in which a second step is added to the embodiment shown in  FIGS. 1A-1D  and  FIG. 2 .  FIGS. 3A and 3B , show a person standing on the lower step preparing to step up onto the second step.  FIGS. 3C and 3D  show a person standing on the upper step preparing to step up into the vehicle. 
         FIG. 4  shows the present invention, a driver&#39;s side step in the preferred embodiment of  FIGS. 3A-3D , as seen from directly overhead. The lower step is shown in the “extended” or “open” position with the upper step still in the “folded” position. 
         FIG. 5  shows the present invention, a driver&#39;s side step in the embodiment of  FIGS. 3A-3D , as seen from directly overhead. The lower step is shown in the “extended” or “open” position with the upper step also in the “extended” or “open” position. 
         FIGS. 6A and 6B  show the present invention as seen from the side and the rear. The motion used to unfold the second step from the retracted to the open position is illustrated. 
         FIG. 7  shows the present invention, a driver&#39;s side step in the embodiment of  FIG. 2 , as seen in elevation from within the subject vehicle in cut away fashion. The step is shown in the “latched”, “extended” or “open” position. A first preferred design of the preferred mechanism of the present invention is illustrated. 
         FIG. 8  shows the embodiment of  FIG. 7  with the step in the “retracted” position. 
         FIG. 9  shows the embodiment of  FIG. 7  with a second preferred design of the mechanism of the present invention. The step is shown in the “latched”, “extended” or “open” position. 
         FIG. 10  shows the embodiment of  FIGS. 3A-3D , again in elevation view, with a third preferred design of the mechanism of the present invention. Both steps are shown in the “latched”, “extended” or “open” position. A secondary latch is illustrated securing the latching plunger in the “latched” position. 
         FIG. 11  shows the embodiment of  FIG. 10  with the second step retracted and the secondary latch unlatched. 
         FIG. 12  shows the embodiment of  FIG. 10  in cut away elevation view showing “over center” locking members which secure the second step in the “extended” or “open” position. 
         FIG. 13  shows the embodiment of  FIG. 10  in a cut away transverse elevation view from the rear as seen from inside the subject vehicle. Both steps are shown retracted. The rollers that restrain the opening of the second step are shown. Also a preferred design of a mounting to attach the invention to a vehicle is shown. A dust shroud is shown in place as well. 
         FIG. 14  is a view similar to  FIG. 13  but with steps extended and with a modified latch device. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention embodies a device or system of devices which, when installed in or on a large vehicle, such as a Class A motorhome, having a interior floor in the driver&#39;s area which is a considerable distance, often three to four feet, above ground level, will greatly reduce the level of athletic ability required to enter or exit the subject vehicle through a driver&#39;s side door. Due to the width of such a subject vehicle, it is desirable and necessary for any device or devices such as those in the present invention to be retracted proximately within the limits of the subject vehicle body for travel on the highway. In the present invention, this retraction and extension of the device or devices used is accomplished by means of a rotary motion or motions. In all of the several preferred embodiments, this rotary motion is controlled automatically in response to opening and closing of the driver&#39;s side door. In all of the several embodiments, the location and orientation of the step surfaces when in the open or extended position allows the person using them to step onto, and bring their whole weight directly and completely above, the subject step surface in the manner in which they normally ascend or descend stairways. 
     The upper two views in  FIGS. 1A and 1B  illustrate the problem which the present invention addresses. Due to the necessity to keep any fixed stepping surface provisions such as stirrups or recessed step pockets, as illustrated here, proximately within the width limits of the subject large vehicle  1 , a person entering or exiting the subject vehicle through the driver&#39;s side door  2  cannot place full weight directly above the supporting step surface. It is, therefore, necessary for the person to support some of their weight by using arms and hands holding onto whatever handhold, handle or object is available when entering or exiting the subject vehicle  1  through the driver&#39;s side door  2 . 
     The lower two views,  FIGS. 1C and 1D , illustrate the present invention in its simplest embodiment. As can be seen in both the side view and the rear view, the person has opened the driver&#39;s side door  2  of the subject vehicle  1  causing a step  3  to rotate out into the extended or open position. The person has stepped up onto the step  3  (which can be called a base step) and is able to stand comfortably with weight fully and directly above the step  3  without need to use arms to help support the person&#39;s weight; that is, the person stands with his center of gravity over the step. 
       FIGS. 1C and 1D  show that the vehicle  1 , a motorhome, has vehicle side panels P extending down alongside the front wheel, which may be essentially down to the center hub of the wheel, at both fore and aft of the wheel. The step  3  swings out from below the panel P, and does not amount to a structure that replaces a panel portion rear of the wheel, as in some truck step structures of the prior art. 
       FIG. 2  further illustrates the present invention in its simplest embodiment showing a top view of the rotation of the step  3  from a retracted position into an extended position. 
       FIGS. 3-6  further illustrate the invention and its use in a two-step embodiment, to be described further below. 
       FIG. 7  further illustrates the present invention in its simplest embodiment showing a view from inside looking outward and toward the side of the subject vehicle. The first preferred mechanism of the simplest embodiment is shown. The step  3  is shown extended, although seen in edge view. The step  3  is shown mounted onto a rotary shaft  7  by means of a commercially available clamp  12 . The shaft  7  is supported rotationally and axially by a lower bearing  8 , mounted on a base plate  10  which is in turn mounted to and supported by a support frame member  11 . The upper end of the shaft  7  is inserted into a commercially available pneumatic rotary actuator  15  which supports it rotationally and serves as a means of rotating the shaft  7  through an arc of 90 degrees, shown in  FIG. 2  as Direction of Rotation  5 , to move the step  3  from the retracted position to the extended position. This action occurs automatically in response to the opening the driver&#39;s side door  2  as illustrated in  FIG. 2 . In the preferred embodiment of the present invention, the opening the driver&#39;s side door  2  as illustrated in  FIG. 2  actuates an electrical switch, preferably of the commercially available “proximity” or “limit” type, which closes an electrical circuit powered by the vehicle&#39;s electrical system and connected to the solenoid of a commercially available pneumatic valve  14 . In the preferred embodiment the pneumatic valve  14  is of the solenoid actuated, spring return “four way valve” type. The valve  14  is piped to the rotary actuator  15  in an arrangement that causes the rotary actuator  15  to return the step  3  to the retracted position when the pneumatic valve  14  is in the spring return position. This ensures that in case of a loss of electrical power, the valve  14  will be set to the “retract” position. The electrical wiring to create the electrical circuit is readily achievable by anyone skilled in the art. 
     Both the rotary actuator  15  and the pneumatic valve  14  are mounted on the base plate  10 . Compressed air is delivered to the pneumatic valve  14  through an air pipe  13 . The compressed air source can be any state of the art system, but the air pressure delivered to the pneumatic valve  14  must be regulated to provide enough driving torque to allow the rotary actuator  15  to rotate the shaft  7  and the step  3 . However, for safety reasons, air pressure should not be so high as potentially to cause injury to a person in the path of the rotational motion of the step  3  as it moves from the retracted position to the extended position and vice versa. Good practice demonstrates that the pressure should be at or below the level that will cause the step  3  to exert a force of approximately five pounds or less at its outermost end. Also for reasons of safety, the preferred embodiment of the present invention includes the use of commercially available air flow rate controllers  17  on the exhaust ports of the pneumatic valve  15 . These flow rate controllers  17  restrict the rate at which the compressed air exits the pneumatic valve  15 . This in turn controls the rate of rotation of the shaft  7  and the step  3  caused by rotary actuator  15  as the step rotates from retracted to extended positions and vice versa. Good practice demonstrates that said rate of rotation should be at or below the rate that will cause the step  3  to take approximately 1.5 to 2 seconds to complete a 90 degree rotation. The limitation of compressed air pressure resulting in limited rotational torque applied to the step  3  necessitates that a means be provided to securely hold the step  3  in the extended position to avoid unsafe movement of the step  3  when stepped upon. Such a means to hold the step  3  is provided in the preferred embodiment by a latching plunger  18  illustrated in  FIGS. 7 ,  8  and  9 . The plunger  18  is mounted on the lower end of a pair of rods which run vertically through a mounting unit  20  which contains a pair of commercially available low friction linear bearings. The upper ends of the rods to which plunger  18  is mounted are in turn attached by a bracket to the cylinder rod of a commercially available spring return air cylinder  19 . The air cylinder  19  is attached to the mounting unit  20 . The spring return action of the air cylinder  19  applies a downward force to the plunger  18  when the air pressure is released when the valve  14  is in the extended position as shown in  FIG. 7 . The plunger  18  mounts a free turning roller on its lower end. The roller, on a horizontal axis, rolls on top of the step  3  while the step  3  rotates into the fully extended position. The plunger  18  rolls over the edge of the step  3  as the step  3  reaches its fully extended position and drops to the limit of its travel, pushed downward by the spring return action of air cylinder  19 . In this fully extended position, the plunger  18  prevents any backward rotational movement in the retracting direction. When the valve  14  moves to the retract position in response to the driver&#39;s side door opening, compressed air is sent to the air cylinder  19  which exerts a force to raise the plunger  18 . When the plunger  18  is raised so that the roller on its lower end clears the top of the step  3 , the step is free to back into its retracted position as shown in  FIG. 8 . 
     Another preferred mechanism of the simplest embodiment of the present invention is shown in  FIG. 9 . This embodiment is identical the embodiment shown in  FIG. 7  and  FIG. 8  with the exception of the substitution of a commercially available air cylinder  16  connected to a lever mounted to the shaft  7  and the addition of a commercially available bearing  9  supporting the upper end of shaft  7 . The bearing  9  and the air cylinder  16  are suitably mounted to the back plate  10 . The full extension of the cylinder  16  causes the shaft  7  to rotate 90 degrees causing the step  3  to go from the extended position to the retracted position. 
     A second preferred embodiment of the present invention is shown in  FIGS. 3A-3D  in which a second or upper step  4  is added to the single lower step  3  of the simplest preferred embodiment shown in  FIGS. 1C and 1D . This upper step  4  seen in  FIGS. 3 ,  4  and  5  unfolds with motion  6  seen in  FIGS. 6A and 6B  from the step  3  referred to in the first embodiment when the first step  3  reaches its fully extended or open position as shown in  FIG. 4 . In its open or extended position, the second step  4  provides a step surface which preferably is approximately mid way between the first step  3  and the subject vehicle floor level and extending laterally well beyond the vehicle body  1  in similar fashion to the first step  3  as shown in  FIG. 5 . Thus, the person can stand on this step without being off balance as shown in  FIGS. 1A and 1B . The second step  4  folds back down into or onto the first step  3  before the first step  3  returns to the retracted position. In the preferred form of this second embodiment of the present invention the second step  4  and its support mechanism is in the form of a parallelogram as seen from the side in  FIG. 12  with pivoting means at all four intersectional points of the parallelogram. A spring preferably of the torsion type located at the lower pivot points of one or more of the pivotal members  22  provides the means to rotate the subject second step  4  into the extended or open position in the manner  6  shown in  FIG. 6A . An air cylinder  24  located in the first step  3  assembly provides the means to rotate the second step  4  from the extended or open position back to the retracted position. Compressed air is supplied from the valve  14  to the air cylinder  24  through the shaft  7  which is bored and tapped for this purpose as shown in  FIG. 11 . 
     In the preferred form of the subject second embodiment, when the extension of the subject steps is initiated by the opening of the driver&#39;s side door  2  as shown  FIG. 4 , the second step  4  is prevented from opening into the extended position by one or more free turning rollers  28 , shown in  FIG. 13 , positioned and fixedly mounted to hold the subject second step  4  down until the first step  3  has reached its fully extended and latched position. At this point, having passed clear of the subject rollers  28 , the second step  4  is free to swing up into its extended position in response to the pressure of the spring action exerted on members  22  seen in  FIG. 12  (springs not shown). Also at this point the latching plunger  18 , which secures the first step  3  in its extended position is itself prevented form retracting by a secondary latch  25  as shown in  FIG. 10 . When closure of the driver&#39;s door  2  triggers the retraction sequence, full retraction of the second step  4 , as shown in  FIG. 11 , releases this subject secondary latch  25  via a catch  25   a  secured to the second step  4  as seen in  FIGS. 11 and 12 . This in turn allows the latching plunger  18  to retract which further allows the first step  3  to return to the retracted position. 
     Also in the preferred form of the subject second embodiment of the present invention, when the second step  4  reaches full extension in the extended mode ( FIG. 12 ), one or more pairs of pivotally mounted and joined longitudinal members  23  and  27  are propelled into an over-center position in relation to each other by a means such as a torsion spring (not shown) at the joining of the subject members  23  and  27 . The distal ends of the subject members are pivotally attached to diagonally opposed corners of the parallelogram formed by the second step  4 , its support members  22  and the first step  3 . Thereby the subject members  23  and  27  rigidly lock the second step  4  in position so long as they remain in the over-center relation each to the other. When the retract action is initiated by the driver&#39;s door closure, the air cylinder  24  mounted in the step assembly, which retracts the second step  4 , moves the subject over-center members  23  and  27  out of the over-center position by its initial movement before continuing to retract the second step  4  with the remainder of its stroke as can be seen from  FIG. 12   
     Another preferred part of both embodiments of the present invention is a mounting means which does not require any drilling, welding, or other modifications to the subject vehicle. 
       FIG. 13  shows schematically one preferred mounting means consisting of a structural member  11  bolted to the backing plate  10  and a main structural member  29  on its other end. The main structural member  29  is rigidly clamped to the vehicle frame F by clamping plates  30 . Additional stability and rigidity is provided by a lower brace member  31  which is also clamped to the subject vehicle frame F using clamping plates  30 .  FIG. 13  also illustrates a sheet metal dust cover  32  provided to keep road dirt thrown up by the vehicle wheels from getting into the mechanism. It should be understood that the step mechanism can be mounted in other ways to the vehicle, such as by bolting to the vehicle frame, if desired. 
     In other embodiments of the present invention, although for obvious reasons the step surfaces on which the person entering or exiting the subject vehicle steps should be approximately horizontal, the axis of rotation or shaft  7  need not be approximately vertical. In fact, in some applications of the present invention, the axis of rotation will need to be inclined at a suitable angle to the vertical and may not even be a physical shaft. The axis of rotation can be virtual in nature formed by two or more bearings so located and mounted as to form the desired axis of rotation around which the subject base step  3  or step assembly  3  and  4  is rotated from the retracted position to the extended position and back to the retracted position. 
       FIG. 14  shows yet another embodiment of the invention with modified step latching. The function of the latching plunger  18  and the secondary latch  25  shown in  FIG. 10 , which is to prevent retraction of the first step  3  before the second step  21  is fully retracted, is replaced by a spring actuated stop  33  pivotally mounted in the first or base step  3 . When the first step  3  reaches the fully extended position in response to the opening of the driver&#39;s side door, the second step  21  is clear of the rollers  28  and begins to rise into its vertically extended position. This action of the second step  21  releases the spring actuated stop  33  to rise in response to its spring force to the position shown in  FIG. 14  directly in line with and in contact with the roller  28 . This action holds the first step  3  firmly in its fully extended position until the spring actuated stop  33  is pushed back down into its retracted position by the full retraction of the second step  21 . This occurs, as explained above, in response to the closing of the driver&#39;s side door  2  or in response to cancellation of the opening action or other loss of electrical power to the driver&#39;s side step system. 
     The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention as defined in the following claims.