Abstract:
The exemplary embodiments herein provide an exercise device having a frame, comprising a first and a second arm, a first end of each arm meeting in fixed angular relationship at a vertex and a second end of each arm extending away from the vertex; a lever arm, having a first and a second end, the first end constrained to rotate about a pin located near the vertex; and a resistance arrangement, configured to convert rotation by a user of a first rotational assembly about an axis on the second end of the first arm into rotation of a second rotational assembly about an axis on the second end of the lever arm, which is converted into rotation of a third rotational assembly about an axis on the second end of the second arm, with the rotation of the third rotational assembly being resisted by a resistive element, the resistance arrangement providing a substantially constant resistance against the rotation of the first rotational assembly by the user over the entire range of the rotation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional of U.S. 61/787,078, filed on 15 Mar. 2013, which is incorporated by reference as if fully recited herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosed embodiments generally relate to compact devices that use the mechanical advantages of pulleys and cams. 
       BACKGROUND OF THE ART 
       [0003]    The benefits of a consistent exercise regimen have been well documented. It is now well accepted that exercising provides a number of health advantages, both in long term effects of preventing disease and in the short term effects of mental awareness, relaxation, and stress relief. It is believed that lack of exercise for an extended period of time (especially for those who are accustomed to regular exercise) can result in increased stress, reduced mental awareness, and resulting poor performance. 
         [0004]    In some situations however, exercise can be very difficult to perform due to a lack of physical space. These situations seem to occur often during space missions, armed forces service on a vessel such as a submarine, or in a congested environment such as a small apartment in a large city. 
       SUMMARY OF THE EXEMPLARY EMBODIMENTS 
       [0005]    The exemplary embodiments herein provide an exercise device having a frame, comprising a first and a second arm, a first end of each arm meeting in fixed angular relationship at a vertex and a second end of each arm extending away from the vertex; a lever arm, having a first and a second end, the first end constrained to rotate about a pin located near the vertex; and a resistance arrangement, configured to convert rotation by a user of a first rotational assembly about an axis on the second end of the first arm into rotation of a second rotational assembly about an axis on the second end of the lever arm, which is converted into rotation of a third rotational assembly about an axis on the second end of the second arm, with the rotation of the third rotational assembly being resisted by a resistive element, the resistance arrangement providing a substantially constant resistance against the rotation of the first rotational assembly by the user over the entire range of the rotation. 
         [0006]    The foregoing and other features and advantages of the present invention will be apparent from the following more detailed description of the particular embodiments, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A better understanding of an exemplary embodiment will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and wherein: 
           [0008]      FIG. 1  is a perspective view of a fully-assembled exemplary embodiment of the exercise device; 
           [0009]      FIG. 2  is a section view of the embodiment of the  FIG. 1  embodiment, showing various strap attachment positions as well as approximate gearing; 
           [0010]      FIG. 3  is a detailed view of one embodiment for the gearing system for turning the large force from the resistive element into a usable load for resistive exercise; 
           [0011]      FIG. 4  is a side view of the resistive element and force adjustment system, showing the curved lever arm with a series of holes that allows the pin to move to different locations on the lever arm, changing the output force of the unit; 
           [0012]      FIG. 5  is a perspective view of an exemplary embodiment of the device when disassembled for storage and 
           [0013]      FIGS. 6A through 6D  are a series of graphs which demonstrate how the constant force is created from the variable force from a gas spring, as well as a force versus displacement curve at maximum load. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. 
         [0015]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/ or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0016]    Embodiments of the invention are described herein with reference to illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 
         [0017]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
         [0018]      FIG. 1  shows, in perspective view, a fully assembled embodiment  10  of the exercise device. The embodiment  10  is shown with a frame  20  that has three rotational assemblies  50 ,  60 ,  70  and a resistive element  80 , the respective rotational assemblies and the resistive element defining a resistive arrangement. In a very broad description of the device, the frame  20  operatively supports the three rotational assemblies  50 ,  60 ,  70  in a manner so that rotation of the first rotational assembly  50  by a user is transferred mechanically through the second rotational assembly  60  and the third rotational assembly  70 , to the resistive element  80 . Because of the manner in which the parts of the embodiment  10  are arranged, the resistance provided to the user at the first rotational assembly is substantially linear and constant. 
         [0019]    At least as importantly, a compact resistive element  80  is able to provide this constant resistance over a range of variable resistance, permitting a free weight exercise to be effectively simulated. A large resistance over a very small distance of movement at the resistive element is converted to a lower resistance, but requiring a larger distance of movement. For example, it is within the scope of the device to provide a resistive load at the output with in an adjustable range of between about  30  to about  500  lbs and a displacement of about one meter or more, which will allow multiple exercises including but not limited to: squats, curls, and deadlifts. 
         [0020]    Looking at the elements of the embodiment  10  more particularly, it is seen that the frame  20  can be arranged as a pair of frame members  22 ,  22 ′ which are, in the depicted embodiment, mirror images of each other. As depicted, the frame members  22 ,  22 ′ are generally “L”-shaped, with each member having a first arm  24 ,  24 ′ and a second arm  26 ,  26 ′. In this “L”-shaped embodiment, a vertex  28  is formed where the first ends of the first arms  24 ,  24 ′ and the first ends of the second arms  26 ,  26 ′ join. In many embodiments, these respective first ends are integrally formed or rigidly joined together Each first arm  24 ,  24 ′ also has a second end  30 ,  30 ′ and each second arm  26 ,  26 ′ has a second end  32 ,  32 ′. The respective second ends  30 ,  30 ′,  32 ,  32 ′ provide sites for locating two of the three rotational assemblies (assemblies  50  and  70 ), as will be explained. 
         [0021]    A further feature of the frame  20  is a lever arm  36 , which is depicted as having first and a second members  38 ,  38 ′, each of which has a first end  40 ,  40 ′ and a second end  42 ,  42 ′. The first ends  40 ,  40 ′ are constrained to limited rotation about a pin  44  or similar member that provides an axis of rotation. The pin  44  passes between the first and second members  22 ,  22 ′ of the frame  20  near the vertex  28 . The second ends  42 ,  42 ′ provide a site for locating one of the rotational assemblies (assembly  60 ), as explained below. 
         [0022]    In the depicted embodiment, the frame  20  also provides a cradle into which the resistive element  80  can be arranged. In this embodiment, the resistive element  80  is positioned along the length of (and between) the pair of first arms  24 ,  24 ′. 
         [0023]    In a preferred arrangement of the embodiment  10 , the respective first arms  24 ,  24 ′ of the frame  20  are each provided in two sections, so that the second arms can be disassembled from transport, as will be explained. 
         [0024]    With the understanding of the frame  20  generally established, the interaction of the parts of the resistive arrangement can be explained. 
         [0025]    Together with  FIG. 1 ,  FIGS. 2 through 4  provide teaching as to how the resistive arrangement operates in the disclosed embodiment. Directing attention first to the first rotational assembly  50 , it is noted that the assembly is positioned at the second end  32 ,  32 ′ of the respective second arms  26 ,  26 ′. A pin, shaft, or similar device  52  provides an axis of rotation for an assembly that has a pair of outer wheels  54 ,  54 ′ with an inner wheel  56  (not visible in  FIG. 1 , but seen in  FIGS. 2 and 3 ). Inner wheel  56  has a smaller radius than the outer wheels  54 ,  54 ′, the latter wheels being preferably identical to each other. Preferably, all three wheels  54 ,  54 ′,  56  are configured as sheaves. All three wheels  54 ,  54 ′,  56  are also arranged for co-rotation about the axis defined by pin  52 . This can be achieved by any of a variety of means, including attachment of the wheels  54 ,  54 ′,  56  to each other and attachment of each wheel to the pin  52 . Outer wheels  54 ,  54 ′ are intended to receive a strap, cable, or other linear tension member (not shown), so that a user can impart rotation to the outer wheels. While the wheels of larger radius are referred to as “outer wheels”, this is only reflective of the depicted embodiment, which is probably preferred, but the wheels could be arranged differently and still provide a functioning embodiment. In the preferred embodiment, the outer wheels are selected to have a radius greater than about 2 times the radius of the inner wheel, and, even more preferably, the wheel radius ratio is about 2.43 to 1. 
         [0026]    The inner wheel  56  is a “roll-up” wheel. By this, it is meant that the inner wheel  56  is configured to have a first end of a belt or strap  62  attached to the wheel, so that rotation of the wheel causes the strap to either be rolled up onto the wheel or payed out from the wheel, depending on the direction of rotation. Belt or strap  62  is actually a part of second rotational assembly  60  and will be discussed below. This belt or strap  62 , as well as the additional belts or straps that will be introduced, are selected to handle a strong tensile force. As a result, a webbed strap material such as, but not limited to a high-strength KEVLAR webbing may be exemplary of the material chosen. 
         [0027]    Moving to second rotational assembly  60 , it is noted that the assembly is positioned at the second end  42 ,  42 ′ of the members  38 ,  38 ′ of lever arm  36 . A pin or similar device  64  provides an axis of rotation for an assembly which in this case has a single wheel  66 , which acts as a classic pulley for the belt or strap  62 . A second end of the belt or strap  62  is attached to the second arms  26 ,  26 ′ at a fixed point  58 , preferably just below the first rotational assembly  50 . It will be understood from this that the rolling up or paying out of the strap  62  on inner wheel  56  causes the second end  42 ,  42 ′ of lever arm  36  to move towards or away from the second end  30 ,  30 ′ of first arm  24 ,  24 ′. Preferably, the second rotational assembly  60  is set up to provide an approximately 2 to 1 pulley effect. 
         [0028]    A further feature of the second rotational assembly  60  is also noted before moving on to the third rotational assembly  70 . The lever arm  36  has a plurality of holes  65  on each of the members  38 ,  38 ′. These holes  65  provide a plurality of locations for anchoring a belt or strap  72  that will be introduced below, as this belt or strap  72  is a part of the third rotational assembly  70 . 
         [0029]    The third rotational assembly  70  is now described. Strap  72  has already been mentioned. A first end of this strap  72  is fixed to one of the holes  65  with a pin or similar means  74 . By selecting which hole  65  is used to place pin  74 , the user can adjust the resistance load provided by the first rotational assembly  50  to the user. However, each hole  65  has been calculated such that the load profile outputted (force consistency vs. displacement) remains unchanged at different load settings. This results in a consistent (flat, linear) load profile at all set points. The second end of the strap  72  is fixed to a roll-up wheel  76  that is positioned between a pair of matching cam shaft pulleys  78 ,  78 ′. As in the first rotational assembly  50 , the cam shaft pulleys  78 ,  78 ′ are arranged on a cam shaft  79  for co-rotation with roll-up wheel  76  about an axis defined by the cam shaft or similar means. This can be achieved by any of a variety of means. When a user rotates outer wheels  54 ,  54 ′ and effects movement of the lever arm  36  towards the second arms  26 ,  26 ′, the belt or strap  72  is payed out from the roll-up wheel  76  by rotating the roll-up wheel. This causes both cam shaft pulleys  78 ,  78 ′ to rotate. 
         [0030]    Finally, resistive element  80  is discussed. In the embodiment disclosed, and selected for its ability to provide a large resistance to a small displacement, is a high-pressure gas spring  82 , however it should be noted that embodiments can utilize other types of resistive elements such as compression springs, hydraulic pressure cylinders, and tension springs. As an example,  FIG. 6A  shows a typical force v extension graph for a commercially-available gas spring  82 . The gas spring  82  has a shaft  84  that can be compressed into a body  86 . By affixing a linear tension means, such as a cord or strap  88  from the shaft  84  to a fixed position on each of the cam shaft pulleys  78 ,  78 ′, the resistance of the gas spring  82  is converted into torque. Based upon the resistance curve in  FIG. 6A , a chart, presented as  FIG. 6B  can be calculated to show the radius of the cam shaft pulley  78 ,  78 ′ that is need to provide a constant torque. The calculated radii from  FIG. 6B  can then be used to generate a cam profile for the cam shaft pulleys  78 ,  78 ′, as seen in  FIG. 6C . Once this is implemented, and by using the preferred pulley ratios, etc.,  FIG. 6D  can be generated to show that the interaction of system components results in a substantially constant output force over a range of displacement at the outer wheels  54 ,  54 ′ from 0 meters to more than 1 meter. 
         [0031]    While the substantially constant output force in  FIG. 6D  is calculated for a theoretical maximum load of 500 lbs, it is notable that a similarly linear plot can be obtained at lesser loads, due to the arc pattern of the plurality of holes  65  on lever arm  36 . The cam pulleys have been designed to create a near constant force. Using the features of the embodiment taught herein, the profile could be designed to create virtually any load profile. Unlike a cam/follower application of the prior art, the design uses the geometric circumference of the cam pulley spline pattern, not just the changing radius. This is because the cam pulley is wrapped with a strap in tension around a portion of the circumference instead of following the radius at a given contact point. The cam design is unique in that it does not follow plate, cylindrical or linear cam designs. The use of a strap wrapped around a cam profile in tension to linearize the force from a non-linear resistive component (i. e. a spring of some type) results in a novel approach for creating a consistent load for resistive exercise. 
         [0032]      FIG. 4  shows a better view of the unique cam profile used to linearize the variable force from the gas spring  82  into a constant torque about the cam shaft  79 . The gas spring is compressed by the strap attachment which is connected to the cam reels. By adjusting the distance between the lever arm pivot point and the strap attachment point, the load experienced by the user can be changed. 
         [0033]      FIG. 5  shows a perspective view of an exemplary embodiment of the device when disassembled for storage. This embodiment of the device would simply need four bolts and subsequently the top arms to be removed to be small enough to be placed in a standard book bag. 
         [0034]    It should be noted that while belts or straps have been shown in the exemplary embodiments herein, embodiments can be practiced with various elongate members, including but not limited to rope, wire, cables, and other members having circular cross sections. 
         [0035]    Having shown and described a preferred embodiment of the invention, those skilled in the art will realize that many variations and modifications may be made to affect the described invention and still be within the scope of the claimed invention. Additionally, many of the elements indicated above may be altered or replaced by different elements which will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.