Abstract:
A wheel arrangement for a four-wheeled vehicle is comprised of a front wheel, two side wheels and a rear wheel, whereas the rear wheel is connected to the frame of the vehicle by a supporting base enabling the same to be steered freely while having a ground-touching point of the same to be biased from the axis of the supporting base by a distance, and the front wheel can be specified as a driving wheel, a free-rolling steering wheel or just a steering wheel with respect to actual requirement, and the two side wheels can be specified as a driving wheels or free-rolling wheels while enabling the axis of the two side wheels to be aligned to a straight line without sharing a same shaft. The wheel arrangement can be a rhombus configuration as the distances between the center of the front wheel and the centers of the two side wheels are the same as that of the center of the rear wheel and the centers of the two side wheels, or can be a diamond configuration as the distances between the center of the front wheel and the centers of the two side wheels are different from that of the center of the rear wheel and the centers of the two side wheels.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a wheel arrangement for a four-wheeled vehicle, and more particularly, to a rhombus or diamond wheel arrangement capable of enabling a vehicle to perform a turn-in-spot without having additional mechanism to be installed thereon. 
       BACKGROUND OF THE INVENTION 
       [0002]    Traffic is the everlasting nightmare for every metropolitan driver, and it is no truer when trying to find a parking place in any major city. To encounter this problem, a vehicle with ability to turn in tight space had been proposed. As the advance of motor and its control technology, some advanced vehicles, especially the rectangle four-wheeled vehicles, are configured with four wheel steering mechanism which cooperates with a motor-driven steering switching mechanism to enable two front wheels of the vehicle to be toe-in and two rear wheels to be toe-out so as to enable the vehicle to turn about in tight space by the help of a corresponding power system. Such vehicles can have good maneuverability and steering that is easy to park and turn around. However, mechanisms, components and controls for enabling a rectangle four-wheeled vehicle to turn-in-spot in tight space are quite complicated, bulky and heavy, moreover, it has adverse affects on wheel and chassis alignment. Particularly, for those smaller size automobiles running in downtown area with quite small internal spaces and the weight thereof are preferred to be reduced for fuel efficiency, the aforesaid four wheel steering mechanism enabling turn-in-spot must be simplified. In addition, the operations of negotiating a turn and making a U-turn in tight space of the rectangle four-wheeled vehicle using the aforesaid four wheel steering are independent to each other, which makes the operations of the mechanism even more complicate. 
         [0003]    A three-wheeled vehicle with one front wheel and two rear wheels is much simpler at system complexity than rectangle four-wheeled vehicle (only two wheels need mechanism control), but the three-wheeled vehicle must enable the two rear wheels to toe-out while steering the front wheel to turn at 90 degrees for enabling the three-wheeled vehicle to turn-in-spot in tight space. Furthermore, without two rear wheels to toe-out, since the forgoing turn is centering about the intersection of the rear wheel shaft and the longitudinal shaft of the vehicle frame, the minimum turning radius is the front and rear wheelbase. Compared with the abovementioned four-wheeled vehicle with ability to turn in tight space, the turning radius of the three-wheeled vehicle is twice as large as that of the four-wheeled vehicle that the three-wheeled vehicle requires large space for turning. 
         [0004]    As to patents of a rhombus four-wheeled vehicle, the representative patents include U.S. Pat. No. 1,262,806, entitled “Rolling Chair”, U.S. Pat. No. 3,828,876, entitled “Motor Vehicle Having Wheels in a Diamond pattern”, U.S. Pat. No. 4,313,511, entitled “Land Vehicle”, U.S. Pat. No. 4,775,021, entitled “Automotive Vehicle Having Four Wheels in a Rhomboidal Configuration”, and so on. The structure and shortcomings of the conventional rhombus four-wheel vehicles are described hereinafter in accordance with the technical means of the above patents. 
         [0005]    Referring to  FIG. 1 , U.S. Pat. No. 1,262,806, entitled “Rolling Chair”, is a pioneer US patent of a rhombus four-wheeled vehicle. The two side wheels  8  are coaxial without speed difference and are driven by an electric motor, whereas the front wheel  10  can be steered manually and the rear wheel  11  can roll freely. The shortcomings of the aforesaid patent are that the driving forces of the two side wheels  8  will interfere with each other while negotiating a turn that the four-wheeled vehicle fails to perform a U-turn in tight space. 
         [0006]    Referring to  FIG. 2 , U.S. Pat. No. 3,828,876, entitled “Motor Vehicle Having Wheels in a Diamond Pattern” disclosed a vehicle having a front wheel R 1  as a steering wheel and two side wheels R 2 , R 3  employed as driving wheels, wherein the axis of the rear wheel R 4  is arranged to parallel to the axis of the side wheels R 2 , R 3  at all time while the rear wheel R 4  is maintained to roll freely without turning. The shortcomings of the aforesaid patent are that: as the axles of the rear three wheels R 2 , R 3 , R 4  are maintained to parallel to each other at all time while being arranged to perpendicular to the longitudinal shaft of the vehicle frame, the lateral force of the rear three wheels R 2 , R 3 , R 4  exerting on the ground can interfere with each other such that the vehicle fails to perform a U-turn in tight space. 
         [0007]    Please to  FIG. 3 , which is a vehicle disclosed in U.S. Pat. No. 4,313,511, entitled “Land Vehicle”. In the vehicle of  FIG. 3 , either the front wheel  19  or rear wheel  21  is employed as a steering wheel through mechanism control while disabling another for steering, and suspension systems  101 ,  103  of the two side wheels  24 ,  27  are controlled through mechanism control to incline inwardly during steering for simultaneously controlling two side wheels  24 ,  27  to turn with the steering wheel (i.e. the front wheel  19  or the rear wheel  21 ). The shortcomings of the aforesaid patent are that although the multiple-wheel control of the aforesaid patent can enhance maneuverability, it is complicated and fails to enable a vehicle to perform a U-turn in tight space. 
         [0008]    Please refer to  FIG. 4 , which is a vehicle disclosed in U.S. Pat. No. 4,775,021, entitled “Automotive Vehicle Having Four Wheels in a Rhomboidal Configuration”. The vehicle of  FIG. 4  has four independent-suspended and independent-driven wheels  2 ˜ 5 , wherein the front and rear wheels  4 ,  5  are respectively suspended by an L-shaped arm, and a steering arm is additionally configured to cooperate with a steering rod extending through the vehicle frame for enabling the front and rear wheels  4 ,  5  to turn simultaneously and opposite to each other, thereby controlling over-steering. The shortcomings of the aforesaid patent are that it requires precise technology to control a multi-wheeled drive system and the vehicle fails to perform a U-turn in tight space. 
       SUMMARY OF THE INVENTION 
       [0009]    In view of the disadvantages of prior art, the primary object of the present invention is to provide a wheel arrangement for a vehicle having four wheels in a rhombus or diamond configuration, capable of enabling the four-wheeled vehicle to perform a turn-in-spot without wheel toe-in/toe-out control mechanism, and thereby enabling the have the four-wheeled vehicle of the invention to have the same turning radius in place as a ordinary rectangle four-wheeled vehicle with wheel toe-in/toe-out control mechanism when the length of the vehicle frames or the wheelbases of the present invention is equal to that of the conventional rectangle four-wheeled vehicle. 
         [0010]    Another object of the present invention is to provide a wheel arrangement for enabling a four-wheeled vehicle to have good maneuverability and steering. 
         [0011]    Yet, another object of the present invention is to provide a wheel arrangement for a four-wheeled vehicle, which enables the four-wheeled vehicle to have a streamline shape with low drag coefficient, and thus greatly reduce fuel consumption in high speed traveling, and is especially fitted to be applied by small size vehicles since the vehicles of such wheel arrangement occupy less road area and thus increase using efficiency of a road while increasing flow of vehicles traveling thereon. 
         [0012]    To achieve the above objects, the present invention provides a wheel arrangement for a four-wheeled vehicle of the present invention, which is comprised of a front wheel, two side wheels and a rear wheel, wherein the rear wheel is connected to the frame of the vehicle by a supporting base enabling the same to be steered freely while having a ground-touching point of the same to be biased from the axis of the supporting base by a distance, and the front wheel is specified as a driving wheel, a free-rolling steering wheel or just a steering wheel with respect to actual requirement, and the two side wheels can be specified as a driving wheels or free-rolling wheels while enabling the axes of the two side wheels to be aligned to a straight line without sharing a same shaft. The wheel arrangement can be a rhombus configuration as the distances between the center of the front wheel and the centers of the two side wheels are the same as that of the center of the rear wheel and the centers of the two side wheels, or can be a diamond configuration as the distances between the center of the front wheel and the centers of the two side wheels are different from that of the center of the rear wheel and the centers of the two side wheels. 
         [0013]    Other objects, advantages and novel features of the present invention will be drawn from the following detailed embodiment of the present invention with attached drawings, in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic view of a conventional rhombus four-wheeled vehicle disclosed in U.S. Pat. No. 1,262,806. 
           [0015]      FIG. 2  is a schematic view of a conventional rhombus four-wheeled vehicle disclosed in U.S. Pat. No. 3,828,876. 
           [0016]      FIG. 3  is a schematic view of a conventional rhombus four-wheeled vehicle disclosed in U.S. Pat. No. 4,313,511. 
           [0017]      FIG. 4  is a schematic view of a conventional rhombus four-wheeled vehicle disclosed in U.S. Pat. No. 4,775,021. 
           [0018]      FIG. 5  is a perspective view of a wheel arrangement for a four-wheeled vehicle of the present invention. 
           [0019]      FIG. 6  is a top plan view of  FIG. 5 . 
           [0020]      FIG. 7  is a side elevation view of  FIG. 5 . 
           [0021]      FIG. 8  shows the meeting of the axis of four wheels of a four-wheeled vehicle while it is negotiating a turn according to the present invention. 
           [0022]      FIG. 9  shows the meeting of the axis of four wheels of a four-wheeled vehicle while it is perform a turn-in-spot according to the present invention. 
           [0023]      FIGS. 10A  is a schematic diagram illustrating a wheel arrangement of a rhombus vehicle according to the present invention. 
           [0024]      FIG. 10B  is a schematic diagram illustrating a wheel arrangement of a conventional rectangle four-wheeled vehicle. 
           [0025]      FIG. 11A  is a schematic diagram illustrating a wheel arrangement of a rhombus vehicle according to the present invention. 
           [0026]      FIG. 11B  is a schematic diagram illustrating a wheel arrangement of a conventional three-wheeled vehicle. 
           [0027]      FIG. 12A  shows a turning radius of a four-wheeled vehicle while it is perform a turn-in-spot. 
           [0028]      FIG. 12B  shows a turning radius of a conventional three-wheeled vehicle while it is perform a turn-in-spot. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Referring to  FIGS. 5-7 , which are respectively a perspective view, a top plan view and a side elevation view of a wheel arrangement for a four-wheeled vehicle in accordance with a preferred embodiment of the present invention. The four-wheeled vehicle  1  includes a vehicle frame  11  and a chassis  12 . Wherein, the front wheel unit  2 , having a front wheel  21  and a pivoting axis A, is disposed at the front of the vehicle frame  11  by connecting the same to the front segment of the vehicle frame  11  using a supporting base  22 . In addition, the vehicle frame  11  further comprises a steering device  13  (illustrated as a shape of a steering wheel, shown in  FIG. 1 ), which is connected to the front wheel unit  2  through a switching mechanism  14 . It is noted that the switching mechanism  14  can be a mechanical structure or an electronic or electrical system. A driver can control the steering device  13  to drive the front wheel unit  2  to steer around the pivoting axis A through the switching mechanism  14 . The maximum steering angle of the front wheel unit  2  is no more than 90 degrees to the right or 90 degrees to the left. The front wheel unit  2  further includes a shock absorber  24  having a resilient member and a damper (not shown). The shock absorber  24  is disposed between the supporting base  22  and a shaft supporting portion  25  connecting the axis C of the front wheel  21 . The point of the pivoting axis A of the front wheel unit  2  projected on the ground is biased from the point of the axis C of the front wheel  21  projected on the ground by a distance C′ (as shown in  FIG. 7 ). Therefore, the reacting force at the ground-touching point of the front wheel  21  and the moment caused by the biased distance C′ enable the front wheel unit to keep progressing straightly. A hub motor  23  is disposed at the front wheel  21 , which is powered by a battery pack  15  disposed on the vehicle frame  11 . The driver can control the hub motor  23  to drive the four-wheeled vehicle  1  to move, which is prior art and so is not described herein. It is noted that the front wheel  21  can be driven by a motor-in-wheel instead of the hub motor  23 . 
         [0030]    Furthermore, right and left side wheel units  3 ,  4  are respectively disposed at opposite sides of a middle segment of the vehicle frame  11 . The right side wheel unit  3  includes a right side wheel  31 , a hub  32 , and a suspension system  33 . The right side wheel  31  can roll freely around the axis E thereof. The suspension system  33  is connected with the chassis  12  to enable the right side wheel unit  3  to be an independently suspended and freely rolling wheel unit. Similarly, the left side wheel unit  4  includes a left side wheel  41 , a hub  42 , and a suspension system  43 . The left side wheel  41  can freely roll around the axis F. The suspension system  43  is connected with the chassis  12  to enable the left side wheel unit  4  to be an independently suspended and freely rolling wheel unit. The axis E of the right side wheel unit  3  and the axis F of the left side wheel unit  4  are collinear and are perpendicular to the longitudinal axis G of the vehicle frame  11 . The axis E and the axis F are not connected directly. 
         [0031]    Secondly, a rear wheel unit  5  is disposed at the rear of the vehicle frame  11 , which includes a rear wheel  51  and a pivoting axis B. The rear wheel unit  5  is connected to the rear segment of the vehicle frame  11  by another supporting base  52 . The rear wheel unit  5  may be steered freely within 360 degrees about the axis B. The rear wheel unit  5  further includes a shock absorber  54  having a resilient member and a damper (not shown). The shock absorber  54  is disposed between the supporting base  52  and a shaft supporting portion  55  connecting the axis D of the rear wheel  51 . The axis D is biased from the pivoting axis B of the rear wheel unit  5  by a distance D′ (as shown in  FIG. 7 ). The hub  56  can freely steer about the axis D. When the four-wheeled vehicle  1  progresses, the force from the ground-touching point of the rear wheel  51  and the moment caused by the biased distance D′ enables the rear wheel unit  5  to freely rotate about the axis B. Thus, the rear wheel unit  5  can adjust itself to align to the progressing direction of the vehicle  1 . 
         [0032]    Referring to  FIGS. 6 and 7 , it must be illuminated that in accordance with the four-wheeled vehicle formed by the front wheel unit  2 , the right side wheel unit  3 , the left side wheel unit  4  and the rear wheel unit  5 , the pivoting axis A, B of the front and rear wheel units  2 ,  5  are located on the longitudinal axis G of the vehicle frame  11 , and the right and left side wheel units  3 ,  4  are isometrically disposed at the opposite sides of the longitudinal axis G of the vehicle frame  11 . Thus, the distance D 1 , D 2 , respectively measured from the front wheel unit  2  to the right side wheel unit  3  and the left side wheel unit  4 , are equal. The distance D 3 , D 4 , respectively measured from the rear wheel unit  5  to the right and left side wheel units  3 ,  4 , are equal. When the axis E, F locate at the center of the front and rear wheel units  2 ,  5 , the wheelbase a of the front wheel and the wheelbase b of the rear wheel are equal, and the distance D 1 ˜D 4  of the wheel units are equal thereby forming a rhombus wheel arrangement. Contrarily, when the front wheelbase a and the rear wheelbase b are not equal, a diamond wheel arrangement is formed (as shown in the dashed of  FIG. 6 ). Furthermore, the front and rear wheelbase a, b are configured equal or unequal in accordance with the requirement of the actual driving performance of the four-wheeled vehicle and the difference of application manner. However, the CG(center of gravity position) H must be configured between the axis C of the front wheel and the axis E, F of the side wheels. 
         [0033]    Compared with the conventional rhombus vehicle (as shown in  FIGS. 1-4 ), since the rear wheel unit  5  of the present invention can freely steer and can forward the CG to the front wheelbase a, the load of the front wheel unit  2  may be configured to be relatively larger, which fits to front wheel drive and so prevents skid of the front wheel drive wheel. Further referring to  FIG. 8 , when the four-wheeled vehicle of the present invention turns (illustrating status of turning left), the rolling axis C, D, E, F of the four wheels  21 ,  31 ,  41 ,  51  meet at a same turning center I thereby avoiding unstable oversteering caused by interference of side forces of the four wheels  21 ,  31 ,  41 ,  51  during negotiating a turn. Referring to  FIG. 9 , when the front wheel  21  is perform a near 90 degrees left turn which is perpendicular to the longitudinal axis G of the vehicle frame, the right side wheel  31  is rolling forward and the left side wheel  41  is rolling opposite thereto while the rear wheel  51  is free to be steer following the direction of the turn. Thus, the four-wheeled vehicle  1  can perform a turn-in-spot, i.e. a stationary turn of gyration. When the front wheelbase a is larger than the rear wheelbase b, the turning radius of the stationary turn of gyration of the four-wheeled vehicle  1  is almost equal to the front wheelbase a. 
         [0034]    Referring to  FIG. 10A  showing a schematic view of a rhombus four-wheeled vehicle of the present invention, and  FIG. 10B  showing a schematic view of a conventional rectangle four-wheeled vehicle, the front and rear wheelbase L 6  and the right and left side tread W 6  of the rhombus four-wheeled vehicle  6  are equal to the front and rear wheelbase L 7  and the right and left side tread W 7  of the rectangle four-wheeled vehicle  7 . Regarding to the static safety factor (SSF), higher SSF means stronger anti-rolling and anti-overturn capability. The value of the SSF, in rectangular vehicle, is equal to the ratio of the length W of a perpendicular line from the CG to the connection line of the front and rear wheels to height h of the CG, that is, SSF=W/h. Therefore, when the height of the CG is the same, the longer length W of the perpendicular line from the CG to the connection line of the front and rear wheels means the larger SSF. As shown in  FIGS. 10A and 10B , when the height of the CG is the same, the perpendicular line V 7  from the CG H 7  of the rectangle four-wheeled vehicle to the connection line of the front and rear wheels is longer than the perpendicular line V 6  from the CG H 6  of the rhombus four-wheeled vehicle to the connection line from the front and side wheels whereby the value of SSF of the rectangle four-wheeled vehicle is larger than that of the rhombus four-wheeled vehicle. As to a small size vehicle with a narrow vehicle frame, that is treads W 6 , W 7  of the right and left side wheels are narrow, the difference of the value of SSF of the rectangle four-wheeled vehicle and the rhombus four-wheeled vehicle is very small. As shown in  FIGS. 10A and 10B , while performing a station turn of gyration, the turning radius R 6  of the rhombus four-wheeled vehicle is slightly smaller than the turning radius R 7  of the rectangle four-wheeled vehicle (the length from the CG to the wheel  71 ). When the rectangle four-wheeled vehicle  7  needs the four wheels  71 ˜ 74  to simultaneously turn, the front wheels  71 ,  72  must turn to be toe-in, and the rear wheels  73 ,  74  must turn to be toe-out, which requires extremely complicated mechanism and control and even adversely affects the wheel position. When the rhombus four-wheeled vehicle  6  of the present invention is performing a station turn of gyration, only the steering of the front wheel  61  is under control, the other three wheels  6218   64  can roll freely, and the rear wheel can self-steer (simultaneously referring to  FIG. 9 ) whereby it does not need an additional mechanism and driving force for controlling. Accordingly, as to the function of station turn of gyration, the rhombus four-wheeled vehicle of the present invention is advantageous. 
         [0035]    Referring to  FIG. 11A  showing a schematic view of a rhombus four-wheeled vehicle, and  FIG. 11B  showing a schematic view of a conventional three-wheeled vehicle, the front and rear wheelbase L 6  and the right and left side tread W 6  of the rhombus four-wheeled vehicle  6  are equal to the front and rear wheelbase L 8  and the right and left side tread W 8  of the three-wheeled vehicle  8 . To consider drivability and prevent from backwards inclining during accelerating, the CG H 8  of the three-wheeled vehicle  8  must be moved forwards. Since the rhombus four-wheeled vehicle  6  has the rear wheel  64 , the CG H 6  of the rhombus four-wheeled vehicle can be configured to extremely close the axis E, F of the two side wheels  62 ,  63 . Thus, when the heights of the CGs are equal, the value of the SSF of the rhombus four-wheeled vehicle  6  is greater than that of the three-wheeled vehicle whereby the rhombus four-wheeled vehicle has more anti-rolling capability. 
         [0036]    Referring to  FIGS. 12A and 12B , as shown in  FIG. 12A  (simultaneously referring to  FIG. 9 ) the front and rear wheelbase L 6  and the right and left side tread W 6  of the rhombus four-wheeled vehicle  6  are equal to the front and rear wheelbase L 8  and the right and left side tread W 8  of the three-wheeled vehicle  8 . When the front wheel  61  of the rhombus four-wheeled vehicle  6  of the present invention is turned 90 degrees and the rear wheel  64  reversely turns 90 degrees for performing a station turn of gyration, the turning radius R 6  of the vehicle  6  is the front wheelbase a. When the three-wheeled vehicle  8  is performing a station turn of gyration as the front wheel turns 90 degrees, the turning radius R 8  is the wheelbase L 8  of the front and rear wheels as the front wheel  81  is the driving wheel and the rear wheels can freely roll. Comparatively, since the front and rear wheelbase L 6  of the rhombus four-wheeled vehicle  6  is equal to the front and rear wheelbase L 8  of the three-wheeled vehicle  8 , the turning radius R 6  of the rhombus four-wheeled vehicle  6  is half of the turning radius R 8  of the three-wheeled vehicle  8  thereby greatly reducing space for turning. 
         [0037]    Further referring to  FIG. 5 , in the preferred embodiment, the front wheel unit  2  has the driving force, and the steering operation device  13  is operated to steer the front wheel unit  2  through the switching mechanism  14 . The right and left side wheel units  3 ,  4  and the rear wheel unit  5  can freely roll. It must be noted that besides the above arrangement, the front wheel unit  2  may be configured to steer only, the right and left wheel units  3 ,  4  are configured as driving wheels, and the rear wheel unit  5  is configured to steer freely, or the front wheel unit  2 , the right and left side wheel units  3 ,  4  are configured as driving wheels, the front wheel unit  2  is still configured to steer and the rear wheel unit  5  is configured to steer freely, or the front and rear wheel units  2 ,  5  are configured to steer freely, the right and left side wheel units  3 ,  4  are configured as driving wheels, but the wheel units  3 ,  4  can individually control power output, rolling direction and speed. The power transmission, speed and direction of rotation of the foregoing driving wheel can be controlled through a driving control unit or mechanism (not shown, belonging to prior art and so not described herein). When the driver controls steering operation device  13 , the driver intent can be transmitted to the control unit through the switching mechanism  14 . When the front wheel unit  2  turns approximately 90 degrees, the driving control mechanism of the right and left side wheel units  3 ,  4  can be actuated to enable one of the right and left side wheel units  3 ,  4  to forwards roll and the other to rearwards roll whereby the four-wheeled vehicle can fix a position to turn in place. The power and rotation speed of the right and left side wheel units  3 ,  4  decide the vehicle to straightly progress, steer or performing a stationary turn of gyration. When the front and rear wheel units  2 ,  5  both can steer freely, the front wheel can naturally turn to the progressing direction during swerving or performing a stationary turn of gyration without additional driving mechanism. 
         [0038]    As described above, the wheel arrangement for a four-wheel vehicle of the present invention has a rhombus or diamond configuration and can have the same radius of turning in place as a rectangle four-wheeled vehicle having switching mechanism for turning in place without additional steering control mechanism when the length of the vehicle frames or the wheelbases of the present invention and the conventional four-wheeled vehicle are equal. Compared with a three-wheeled vehicle, the wheel arrangement for a four-wheel vehicle of the present invention has more advantages. The wheel arrangement for a four-wheel vehicle of the present invention upgrades drivability and motility. The streamline shaped four-wheeled vehicle of the invention has a low wind resistance coefficient which greatly reduces fuel consumption during high speed traveling. The wheel arrangement for a four-wheel vehicle of the present invention is especially fitted to be applied by small size vehicles since the vehicles of such wheel arrangement occupy less road area and thus increase using efficiency of a road while increasing flow of vehicles traveling thereon. 
         [0039]    While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.