Abstract:
To enable immediate and easy-to-understand confirmation of heat-dissipation capability only by entering shape data of a radiator without switching screens. Shape data input sections and a shape display section for a radiator, and a graph display section which displays the calculated result as a graph are adapted to be displayed on the identical screen of the screen device. The pattern diagram of a radiator shape and the result of heat-dissipation capability can be seen on the graph simultaneously only by entering the shape data of the radiator without switching the screen.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is related to Japanese Patent Application No. 2003-430855 filed on Dec. 25, 2003 the entire contents of which are hereby incorporated by reference.  
         [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a radiator heat-dissipation simulation system using a computer for calculating heat-dissipation capability of a vehicle radiator and displaying the result on a screen of the display device.  
         [0004]     2. Description of Background Art  
         [0005]     When estimating a heat-dissipation capability of a vehicle radiator having a water-cooled engine mounted thereon, a composite coefficient of heat transfer of a coefficient of heat transfer from cooling water flowing in channels of cooling pipes (metal pipes) which constitute the radiator to inner walls of the metal pipes, a coefficient of heat transfer from the inner wall of the metal pipe to an outer wall of the metal pipe, and a coefficient of heat transfer from the outer wall of the metal pipe to the outside air is taken into consideration. Also, it is necessary to take the flow rate of water into consideration for the coefficient of heat transfer from water to the inner wall of the metal pipe. Furthermore, in addition to the coefficient of the heat transfer of the cooling pipes, the length of the cooling pipes, the number of stages of the cooling pipes which constitute the radiator, and further, the fact that the air velocity or the like affects the cooling capability are taken into consideration to estimate the performance of the radiator.  
         [0006]     In other words, the heat-dissipation capability, for example, the amount of heat-dissipation is calculated as a value of a function (estimated value) by an expression using parameters of data on the shape of the radiator and the structure of the cooling pipes as variables.  
         [0007]     Accordingly, when estimating the heat-dissipation capability of the vehicle radiator having a water-cooled engine mounted thereon in the related art, the estimated value is obtained by substituting variables in various expressions by manual calculation using a calculator, spreadsheet software, or an expanded function thereof (macro).  
         [0008]     A technology to display the contents calculated by a super computer with regard to a simulation analysis of an electric circuit on a graphic display is proposed. However, the technology is not provide a simulation of the heat-dissipation of the vehicle radiator. See, JP-A-60-7550,  FIG. 3 .  
         [0009]     As described above, when estimating the heat-dissipation capability of the vehicle radiator having the water-cooled engine mounted thereon in the related art, there is a problem in that the input operation including the input of numerical values via a keyboard and the reading of the numerical value and the result reading operation are complicated.  
         [0010]     Also, since the shape of the radiator is processed simply by entering numerical values of the dimensional data, the shape of the radiator cannot be imaged by intuition. Therefore, there is a problem in that it is quite difficult to know the causal relation between the result of the calculation and the shape by intuition.  
       SUMMARY AND OBJECTS OF THE INVENTION  
       [0011]     In view of such problems, it is an object of the present invention to provide a radiator heat-dissipation simulation system for enabling visceral comprehension of the causal relation between the shape and the heat-dissipation capability of the radiator.  
         [0012]     A radiator heat-dissipation simulation system of the invention is a radiator heat-dissipation simulation system using a computer in which the heat-dissipation capability of a vehicle radiator is calculated and the result of calculation is displayed on a screen of a display device. The system includes a shape data input section for entering the shape data of the radiator. A shape display section is provided for displaying the geometric shape of the radiator calculated by the computer based on the entered shape data. An environmental conditions input section is provided for setting and entering the environmental conditions of the vehicle with a graph display section for calculating the heat-dissipation capability of the radiator by computer based on the entered shape data and the environmental conditions and displaying the calculated result as a graph. The shape data input section, the shape display section, the environmental condition input section, and the graph display section are displayed on the identical screen of the display device.  
         [0013]     According to the present invention, since the shape data input section and the radiator shape display section, the vehicle environmental condition input section, and the graph display section for displaying the calculated result as a graph are displayed on the identical screen of the display device, a drawing of the radiator shape and the result of the heat-dissipation capability (characteristic) can be viewed simultaneously as a graph without switching the screen only by entering the shape data of the radiator (no complicated screen switching operation is necessary). In other words, since a change of the shape and the influence thereof (the result of the heat-dissipation capability) are displayed on the identical screen visually and immediately, the relationship between the shape and the heat-dissipation capability of the radiator can be comprehended by intuition.  
         [0014]     When displaying the calculated result as a graph, the result of numerical values can be displayed on the graph display section (graph/value of numerical value display section) simultaneously with the graph.  
         [0015]     In this case, by dividing the screen into left and right sides and displaying the input-system screen including the shape data input section, the shape display section, and the environmental condition input section on the identical screen of the display device together with the graph display section, comprehension of the output result is facilitated. In other words, since the screen is divided into the input system and the output system, the screen is eye-friendly.  
         [0016]     Since the radiator shape data includes the number of stages of the cooling pipes constituting the radiator, the shape of the cross-section of the cooling pipes, and an upper side and a lower side of the radiator when the radiator contour is assumed to have a trapezoidal shape, and the vehicle environmental conditions include the air velocity and the outside air temperature corresponding to the velocity of the vehicle, the heat-dissipation capability can be estimated by changing the main data (parameters) and changing the shape.  
         [0017]     When the radiator is necessary to be provided with a cooling fan, with a configuration in which the shape data of the cooling fan of the radiator is entered via the shape data input section, and the geometrical shape of the cooling fan is displayed on the shape display section, the relation between the shape of the radiator including the cooling fan mounted thereon and the heat-dissipating capability can be comprehended by intuition.  
         [0018]     According to the present invention, since the radiator shape data input section, the radiator shape display section based on the shape data, and the graph display section for displaying the result of the heat-dissipation are displayed on the identical screen, the relation between the shape and the heat-dissipation capability of the radiator can be comprehended by intuition.  
         [0019]     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
         [0021]      FIG. 1  is a block diagram of a radiator heat-dissipation simulation device to which the radiator heat-dissipation simulation system according to an embodiment of the invention is applied;  
         [0022]      FIG. 2A  is a pattern perspective view of a general radiator;  
         [0023]      FIG. 2B  is a pattern cross-sectional view of the general radiator;  
         [0024]      FIG. 3  is an explanatory drawing of an input system screen of a display device;  
         [0025]      FIG. 4  is an explanatory drawing showing an input system screen and an output system screen of the display device;  
         [0026]      FIG. 5  is a flowchart of a simulation process according to the present embodiment; and  
         [0027]      FIG. 6  is an explanatory drawing of an input screen of the display device when being switched to a cooling fan “presence”. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     Referring now to the drawings, embodiments of the present invention will be described wherein  FIG. 1  illustrates a structure of a radiator heat-dissipation simulation device  10  to which the radiator heat-dissipation simulation system according to an embodiment of the present invention is applied. As is understood from  FIG. 1 , the radiator heat-dissipation simulation device  10  is composed of a personal computer or the like, and basically includes an input device  14  including a keyboard, a mouse, etc., a display device  16  such as a CRT display device or a liquid crystal display device, and a computer body  18  which is to be connected thereto.  
         [0029]     The computer body  18  is a calculator and includes, though not shown, a CPU (central processing unit), a ROM as a memory (EEPROM is also included), a RAM (random access memory), or HDD (hard disk drive), an I/O device, a timer as timing means and serves as a control unit, a calculating unit, and a processing unit. The ROM or the HDD includes a program to be read into the RAM and executed by the CPU when executing calculation stored therein, and the function block of the program to be executed by the CPU (computer) is shown in the block diagram in the computer body  18  shown in  FIG. 1 .  
         [0030]     In other words, the computer body  18  includes an input processing unit  20  for converting the input via the input device  14  into data and outputting the same, a geometrical shape calculating unit  22  for calculating the geometrical shape of a radiator based on the input data, a heat-dissipation capability calculating unit  24  for calculating the heat-dissipation capability of the radiator based on the input data, and a display processing unit  26  for generating video signals for displaying on a screen based on input data and the result of calculation obtained by the geometrical shape calculating unit  22  and the heat-dissipation capability calculating unit  24 .  
         [0031]      FIG. 2A  and  FIG. 2B  show a pattern diagram of a radiator  30  to be mounted on a vehicle, for example, on a motorcycle. The radiator  30  includes a layer structure having cooling pipes  32  in which cooling water flows, and fins  34  for improving the heat-dissipation efficiency. The radiator  30  is trapezoidal shape (including square shape) when viewed from the front where flow of air  36  hits, for example. The radiator  30  is connected to a water pump, not shown. Then, water supplied from a water inlet port  40  by a water pump and flowing in the cooling pipes  32  is cooled by the outside air temperature, the flow of air  36 , the cooling pipes  32 , the fin  34 , or the cooling fan (not shown), and is outputted from a water outlet port  38 . Water outputted from the outlet port  38  flows in a jacket of an engine (not shown) through the water pump and cools the engine, and water which received heat from the engine is returned from the water inlet port  40  into the radiator  30 .  
         [0032]     The heat-dissipation calculating unit  24  shown in  FIG. 1  includes an expression, wherein x represents given positions of the cooling pipes  32  in the longitudinal direction, T(x) represents a water temperature, and Ta represents an outside air temperature, stored therein. The expression is a differential equation, and is represented by the following expression (1). 
 
 dT/dx =−( T−Ta ) K/u −( T   4   −Ta   4 ) M/u    (1) 
 
         [0033]     Here, u represents the flow rate of water, K represents a constant value which contributes to a heat transfer from water to the outer walls of the cooling pipes  32  (the wall which comes into contact with air) (determined by the shape of the cooling pipes, the composite coefficient of heat transfer, and the like), and M represents a constant value which contributes to heat radiation from the outer walls of the cooling pipes  32  (determined by the shape of the cooling pipes and Stefan-Boltzmann&#39;s constant). These constants of the differential equation are determined by various experiments.  
         [0034]      FIG. 3  shows a screen  50  of a display device  16 . The screen  50  is basically constructed of a single screen including an input system screen  52  on the left half side when viewed from the front, and an output system screen  54  on the right half side when viewed from the front.  
         [0035]     The input system screen  52  includes shape data input sections  54 A,  54 B for entering the shape data (parameters) of the radiator  30 , which is entered via the input device  14  and is processed by the input processing unit  20 , a shape display section  56  for displaying the geometrical shape of the radiator calculated by the geometrical shape calculating unit  22  based on the entered shape data, an environmental condition input section  57  for setting the environmental conditions of the vehicle, which is entered via the input device  14  and processed by the input processing unit  20  and entering the same, and a flow velocity input section  58  for setting a flow rate Um of a flow flowing in the respective cooling pipes  32  and distribution of the flow velocity and entering the same. Although the flow velocity Um is actually illustrated by the length of the arrow in the cooling pipe  32  in the radiator  30  displayed on the shape display section  56 , since it makes the illustration thereof complicated, it is omitted in  FIG. 3 .  
         [0036]     The shape data input section  54 A provided at the left upper corner on the screen  50  is a screen that a user input data such as a width w (“24.0”, “mm” are entered as an example), a height h (“2.0”, “mm” are entered as an example), and thickness t (“0.3”, “mm” are entered as an example) of a cross-sectional shape of the cooling pipe  32  via the input device  14  such as a mouse, a keyboard, or the like.  
         [0037]     The shape data input section  54 B provided on the lower left side on the screen  50  is a screen including a slider  59  that allows a change in the values by pointing with the mouse pointer, clicking the left button of the mouse, and dragging the slider. The screen permits the user to enter data such as, when the contour of the radiator  30  viewed from the front has a trapezoidal shape, a length of the upper side L 1  (“0.152”, “m” are entered, for example), a length of the lower side L 2  (“0.092”, “m” are entered, for example), the number of stages N of the cooling pipes  32  (“25”, “stages” are entered, for example), and reduction and enlargement ratios (“1.3”, “times” are entered, for example) via the input device  14  such as the mouse.  
         [0038]     Furthermore, the environment condition input section  57  provided likewise on the lower left side on the screen  50  is a screen including the slider  59  which allows a change in the value by pointing with the mouse pointer and clicking by the left button of the mouse, and dragging the slider  59 . The screen permits the user to enter data such as an outside air temperature Ta (“10° C.” is entered for example) and a air speed U corresponding to the vehicle speed (“8.0” (m/s)) corresponding to the vehicle speed 28.8 (km) is entered, for example) using the input device  14  such as the mouse.  
         [0039]     The flow rate input section  58  provided on the upper center on the left side of the screen  50  is a screen including the slider  59  for allowing the change of the value (deviation) by pointing with the mouse pointer, clicking by the left button of the mouse, and dragging the slider  59 . The screen permits the user to enter data such as the flow velocity distribution indicating that cooling water in all the cooling pipes  32  flow at a uniform flow rate, or a non-uniform flow rate which changes gradually by each cooling pipe  32  with deviation (the flow velocity is relatively higher on the upper side and lower on the lower side of the radiator  30 , or vice versa) using the input device  14  such as the mouse. The basic flow rate Um can be entered via the input device  14  such as the keyboard (Um=0.96 (m/s) is entered, for example). A fin presence/absence button on the lower right on the screen (fin presence/absence input section)  60  is a screen for switching between “fin-presence” and “fin-absence” according to whether the fins are to be mounted or not, and is set to “fin-presence” as a default. Furthermore, on the lower side of the fin presence/absence input section  60  on the screen, there is provided a cooling fan presence/absence button (cooling fan presence/absence input section)  61  which is a screen for switching between the cooling fan “presence” and the cooling fan “absence” depending on whether the cooling fan is to be mounted to the radiator  30  or not.  
         [0040]     When the width w, the height h, the thickness t, the length of the upper side L 1 , and the length of the lower side L 2  of the shape of the cross-sectional are of the cooling pipe  32 , the number of stages N of the cooling pipes  32 , and the reduction and enlargement rates are supplied on the shape data input sections  54 A,  54 B using the input device  14 , the input processing unit  20  supplies the input data to the geometrical shape calculating unit  22 .  
         [0041]     The geometrical shape calculating unit  22  calculates the shape of the radiator  30  having the shape and the number of stages corresponding to the input data based on the input data, and sends the calculated result to the display processing unit  26 .  
         [0042]     The display processing unit  26  generates video signals for displaying the radiator having the shape and the number of stages corresponding to the input data on the center of the left side of the screen  50  based on the calculating result from the geometrical shape calculating unit  22  and the various input data from the input processing unit  20 , and sends the generated video signals to the display device  16 .  
         [0043]     The display device  16  displays the input system screen  52  mainly on the left side in  FIG. 3  on the screen  50  based on the video signals for display.  
         [0044]     After having finished the setting of the geometrical shape of the radiator  30  displayed on the left half and setting the display thereof on the screen, a calculation start button  62  is pressed (clicked) via the input device  14  such as the mouse. With this operation, the heat-dissipation capability calculating unit  24  references the input data described above, and the heat-dissipation capability is calculated based on the expression described above, which is stored in advance. In this embodiment, temperature lowering characteristic and heat-dissipation amount characteristic are calculated as the heat-dissipation capability. By sending the result of calculation to the display processing unit  26 , a graph display section (also referred to as graph/numerical value display section or result display section)  64  is displayed including a temperature lowering characteristic display section  64 A on the output-system display  54  on the right side of the display device  16  and a heat-dissipation amount characteristic display section  64 B.  
         [0045]      FIG. 4  shows a screen  50 A on which a temperature lowering characteristic  66  and a heat-dissipation amount characteristic  68  calculated by the heat-dissipation calculating unit  24  are displayed on the graph display section  64 . The temperature lowering characteristic  66  displayed on the lower right side of the display  50 A shows a flow rate Q (L/min) on the lateral axis and the temperature lowering ΔT (K) of cooling water between the inlet and outlet ports  40 ,  38  of the radiator  30  on the vertical axis.  
         [0046]     The heat-dissipation amount characteristic  68  displayed on the upper right side of the display  50 A shows the flow rate Q (L/min) on the lateral axis and a heat-dissipation amount H (kW) on the vertical axis.  
         [0047]     In this case, the full scale is displayed on a flow rate display window  70  of the flow rate Q on the lateral axis (the full scale flow rate (maximum flow rate on the lateral axis) X=100 (L/m) for example). The full scale flow rate X can be adjusted by a slider  72 .  
         [0048]     The full scale of the temperature lowering characteristic  66  (vertical axis full scale) is 16 (K) as shown on a display window  74  for example, the value can be changed by a slider  76 .  
         [0049]     Furthermore, the full scale of the heat-dissipation characteristic  68  (vertical axis full scale) is 28.0 (kW) as shown on a display window  78  for example, however, the value can be changed by a slider  80 .  
         [0050]     Still further, red-colored cross-shaped cursors  82 ,  84  are provided which move along the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68  for reading the temperature lowering ΔT and the heat-dissipation amount H corresponding to a certain flow rate Q in the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68  as resulting numerical values.  
         [0051]     By moving a slider  86  in the lateral direction, the cross-shaped cursors  82 ,  84  move in the same direction along the curves on a graph indicating the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68 . At this time, the cross-shaped cursors  82 ,  84 , and the flow rate Q on the lateral axis is displayed in a flow rate display window  88  as the numerical value result display section (Q=47.1 (L/min) is displayed, for example) as the value of the intersection between the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68 , that is, as the resulting numerical value and, in the same manner, the temperature lowering ΔT is displayed in a temperature lowering display window  90  as the resulting numerical value display section (ΔT=7.53 (K) is displayed for example). Furthermore, the heat-dissipation amount H is displayed on a heat-dissipation amount display window  92  (H=24.25 (kW) is displayed for example).  
         [0052]     In this case, by changing the shape of the radiator  30  (the shape is entered again) by the shape data input section  54 A,  54 B on the input system screen  52  on the left half and pressing the calculation initiating button  62  again, the graphs of the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68  are displayed in an overlapped manner. By pressing a delete button  94 , the screen  50  before displaying the graphs shown in  FIG. 3  is restored.  
         [0053]     In this manner, the embodiment described above is, when described and also referring to a flowchart shown in  FIG. 5 , a radiator heat-dissipation simulation system using a computer for calculating the heat-dissipation capability of the vehicle radiator  30  (in this embodiment, the heat-dissipation characteristic  68  and the temperature lowering characteristic  66 ) and displaying the result on the screen  50 ,  50 A of the display device  16 . The system includes shape data input sections  54 A,  54 B for entering the shape data of the radiator  30  (Step S 1 ), a shape display section  56  for displaying the geometric shape of the radiator  30  calculated by the computer (the geometrical shape calculating unit  22 ) based on the entered shape data (Step S 2 ), environmental conditions input section  57  for setting and entering the environmental conditions of the vehicle (Step S 3 ), and a graph display section  64  for calculating the heat-dissipation capability of the radiator by the computer based on the entered shape data and the environmental conditions (Step S 4 ) and displaying the calculated result as a graph and a numerical value (Step S 5 ). The shape data input sections  54 A,  54 B, the shape display section  56 , the environmental condition input section  57 , and the graph display section  64  are displayed on the identical screen  50 ,  50 A of the display device  16 .  
         [0054]     Since the shape data input sections  54 A,  54 B and the shape display section  56  relating to the radiator  30 , the environmental condition input section  57  relating to the vehicle, and the graph display section  64  for displaying the calculated result as a graph are displayed on the identical screen  50 ,  50 A of the display device  16 , the pattern diagram of the radiator shape and the result of the heat-dissipation capability (characteristic) can be viewed as a graph simultaneously only by entering the shape data of the radiator  30  without switching the screen. In other words, since the change of the shape and the influence (the result of the heat-dissipation capability) are displayed on the identical screen  50 ,  50 A visually and immediately, the relation between the shape and the heat-dissipation capability of the radiator  30  can be comprehended by intuition.  
         [0055]     The temperature lowering ΔT and the heat-dissipation amount H, which are the results in numerical value corresponding to the specific flow rate (the flow rate to be noted) Q can be read (Step S 7 ) by the cross-shaped cursors  82 ,  84  which can be moved along the graphs of the temperature lowering characteristic  66  and the heat-dissipation amount characteristic  68  by the operation of the input device  14  (Step S 6 ). Thus, whether or not the desired result could be obtained can be confirmed easily, and if the desired result could not be obtained (Step S 8 ), the steps from S 1  to S 7  described above may be repeated until the desired result can be obtained.  
         [0056]     In this case, as will be understood from the screen  50 ,  50 A, the input system display  52  having the shape data input sections  54 A,  54 B, the shape display section  56 , and the environmental condition input section  57 , and the graph display section  64  are displayed on the identical screen  50 ,  50 A of the display device  16  by diving the screen into a left part and a right part. Thus, the output result can be easily comprehended. In other words, the screen is eye-friendly because the screen  50 ,  50 A is divided into the input system and the output system.  
         [0057]     Here, by employing the number of stages N of the cooling pipes  32  which constitute the radiator  30 , the shape of the cross-section of the cooling pipes  32 , and the upper and bottom sides when the contour of the radiator  30  is a trapezoidal shape as the shape data of the radiator  30 , and employing the air velocity U corresponding to the vehicle velocity and the outside air temperature Ta as the environmental conditions of the vehicle, an estimation of the heat-dissipation capability is effectively enabled by changing the main data (parameters) and changing the shape.  
         [0058]     When it is determined to be necessary to mount the cooling fan to the radiator  30  from the calculated result or the like, the presence/absence button  61  of the cooling fan is switched to the cooling fan “presence” and then the shape data of the cooling fan is entered in the process of entering the shape data of the radiator  30  in Step S 1  described above.  
         [0059]      FIG. 6  is an explanatory drawing of the input screen  50 B of the display device  16  when the cooling is switched to the cooling fan “presence.” 
         [0060]     On the screen  50 B, a shape data input section  54 C for the cooling fan for entering and changing the size of the cooling fan, entering and changing the position of the same, and entering and changing the number of the same is displayed. In addition, a fan air velocity input section  98  for the cooling fan for changing the air velocity (displayed to be 8.0 (m/s) on the screen) of a slider  96  is displayed.  
         [0061]     In this case, the geometrical shape of two cooling fans  101 ,  102  calculated by the geometrical shape calculating unit  22  in Step S 2  as well as the geometrical shape of the radiator  30  including the cooling fans  101 ,  102  mounted thereon are displayed in the shape display section  56  on the screen  50 B.  
         [0062]     Here, it is understood from the display of the shape data input section  54 C of the cooling fan that the two cooling fans  101 ,  102  are used, and the shape of the cooling fan  102  is being adjusted. The data of the cooling fan  102  is “84”(mm) in outer diameter, “26” (mm) in hub radius, “325”(mm) in the central coordinate X, “149” (mm) in the central coordinate Y as the parameters which can be changed by a slider  104 . By pressing a “close” button  106 , the display of the shape data input section  54 C for the cooling fan can be cleared, while by setting the presence/absence button  61  for the cooling fan to the cooling fan “presence” again, the display appears. Actually, the shape data input section  54 C of the cooling fan is displayed on the graph display section  64  in the overwritten manner.  
         [0063]     By pressing the calculation start button  62  in this state, the heat-dissipation capability calculating section  24  calculates the preset heat-dissipation capability of the cooling fans  101 ,  102  (Step S 4 ), and the new results of the calculation are displayed as the temperature lowering characteristic  66  and the heat-dissipation characteristic  68  on the graph display section  64  as in  FIG. 5  (step S 5 ).  
         [0064]     The present invention is not limited to the above-described embodiment and, for example, the system can easily be extended in such a manner that the contour of the radiator is formed into a given shape corresponding actually to the vehicle to which the water-cooled engine or the like is mounted; not the trapezoidal shape, but the quonset or asymmetry shape based on the present invention. Thus, various configurations may be employed.  
         [0065]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.