Abstract:
An improved belt tensioner for a refrigerant compressor mounted on a plate of a bus engine compartment, the compressor being operated by a power take off from the engine via a belt drive, the belt tensioner being flange mounted with a single plate attached to a single screw drive bolt, the plate being pushed against the compressor a predetermined and preset distance as determined by markers on a spring tension gauge mounted in between the single plate and the flange wherein the flange is fixed to the plate.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a belt tensioner for use on a belt which is spanned between a power take off from the transmission of an internal combustion engine and its air conditioning compressor, and more particularly to a belt tensioner which can obtain an optimum tension force applied on the belt using a single adjusting rod coupled to a pivoting engaging member.  
           [0003]    2. Description of the Prior Art  
           [0004]    In the prior art, an internal combustion engine for a mass transport motor vehicle such as a bus generally has a crank pulley, an alternator, an air conditioning compressor, and a V-belt spanned between the crank pulley, the compressor, and the alternator. The rotation of the crank pulley is transmitted through the V-belt to the compressor. If the tension force applied onto the V-belt is greater than an adequate value, this impairs the endurance of bearings employed for the compressor. Conversely, if the tension force applied onto the V-belt is less than the adequate value, this causes a slippage of the V-belt and further a decrease in the cooling effected by the compressor and in an amount of an electric power generated by the alternator.  
           [0005]    In general, a tension force applied onto the V-belt is adjusted by a procedure whereby a set of push rods attached to push blocks resting against the compressor are individually moved backwards or forwards to adjust the position of the compressor after bolts mounting the compressor onto a mounting plate attached to the engine are sufficiently loosened. After adjustment the tension of the belt is checked with a tension gauge and further adjusted as necessary to obtain the desired tension on the belt driving the compressor.  
           [0006]    Thus, in the prior art arrangement at least two push blocks and associated rods are used for tension adjustment. A worker sets an optimum tension force while another worker measures the amount of a tension force applied on the V-belt or other belt. However, with the two push rods it is difficult to easily set an optimum belt tension force. The use of two mechanics is labor intensive and expensive. Moreover, the use of two push rods sometimes unnecessarily results in skewing of the compressor pulley out of the plane of motion of the belt.  
           [0007]    By way of background, in 1930 Thompson received U.S. Pat. No. 1,783,987 for a chain adjusting device. The device automatically takes up slack in an auto drive chain when it becomes objectionably tight by using a spring loaded sprocket pressing against the chain.  
           [0008]    In 1957 Gehre was issued U.S. Pat. No. 2,806,382 for a belt tensioning device. This device maintains a predetermined tension of a belt in driving relation with a pulley attached to an automobile engine by using a compressed spring in a manner similar to that used by Thompson for a chain and provides an indicator means comprising an indicator needle for ascertaining by visual inspection the degree of belt stretching resulting from prolonged service.  
           [0009]    In 1961 Murray was issued U.S. Pat. No. 2,985,027 for a slack adjuster or device for adjusting the slack in a chain or belt drive. This device operates by expressing force directly against the chain or belt at a point in between the drive pulley and the driven pulley.  
           [0010]    In 1974 Pfarrwaller was issued U.S. Pat. No. 3,817,113 for a chain drive with an idler wheel tensioning means biased by elongated pads. Pfarrwaller improves the tensioned adjusted chain drive wherein the tension is abruptly adjusted by a third member acting against the chain by using resilient material to support the third member, and the resilient material acts as a shock absorber and allows the third member to be deflected.  
           [0011]    Murray is similar in operation and structure to U.S. Pat. No. 4,509,934 which issued on Apr. 9, 1985 to Ballius for an external transfer case chain slack adjustment structure. Ballius employs a roller which inwardly deflects a chain and is rollingly engaged with slack reach of the chain.  
           [0012]    In 1986 Kawasawa et al. was issued U.S. Pat. No. 4,583,961 for a V-belt tensioner which is spanned between the driving member and a driven member. A rotatable adjustment bolt moves a bracket which slidably supports a slider secure to the driven member. The adjustment bolt is spring biased to fix its position.  
           [0013]    On Jul. 9, 1991 Bryant was issued U.S. Pat. No. 5,030,173 for a spring loaded telescopic tube take-up. The device is a belt take-up for a conveyor wherein the belt take-up is provided with an internal compression spring to adjustably bias the bearing support tube to control tension on a conveyor belt. A scale which indicates tension is further disclosed and used with a load circuit to stop the conveyor at extremely high or low tension readouts.  
           [0014]    On Mar. 19, 1996 Tsai et al. was issued U.S. Pat. No. 5,499,950 for a belt tensioner and actuator. The belt tensioner and the actuator of the tensioner employs classic third party transverse forced applied to the belt. The assembly has a rotatable shaft that is operatively interconnected to a spring and is provided with opposite ends one of which is operatively interconnected to a piston.  
         OBJECTS OF THE INVENTION  
         [0015]    It is accordingly a primary object of this invention to provide a belt tensioner for a bus vehicle compartment and platform which provides a single vector force orthogonal to compressor surface which is in turn orthogonal to the plane or rotation of a pulley and belt assembly by adjusting single push rod.  
           [0016]    It is an object of the present invention to provide a combination of a demountable bracket and a belt tensioner actuated by a single rod connected to an engaging member adapted for engaging a compressor wall which is pivotingly attached to a force delivering end of the rod.  
           [0017]    It is an object of the present invention to provide a combination of a demountable bracket, a belt tensioner actuated by a single rod connected to a single engaging member for engaging a compressor which is pivotingly attached to a force delivering end of the rod.  
           [0018]    It is an object of the invention to provide an improvement in a method for adjusting the tension of a belt drive for a refrigerant compressor by eliminating steps requiring the adjustment of parallel force vectors to adjust the tension of the compressor belt.  
           [0019]    To attain the above objects, a belt tensioner according to the present invention, adjusts a belt tension force of a belt for transmitting a torque of a driving member which is mounted on a main body to a driven member which is rotatably mounted on the main body. The belt tensioner has a novel adjust means, a bracket secured to the main body, and a slider secured onto the driven member at one end thereof The adjusting means includes a head portion, a first shaft portion which has a thread-engaging relationship with a threaded hole provided in the bracket, and a second shaft portion which slidably supports the slider. The adjust means is constantly biased by the biasing means which is provided between the head portion and the bracket. When the adjust means rotates to obtain an optimum belt tension force, the slider approaches the first shaft portion according to the rotation of the adjust means. Further, the adjust means rotates, thereby reacting to the condition that the first shaft portion fits into the hole within the bracket. Finally, when the head portion comes in contact with the bracket, the optimum belt tension force is obtained.  
         SUMMARY OF THE INVENTION  
         [0020]    The novel structure and method embodying the teachings of the present invention enables more efficient adjustment of the belt tension for a refrigerant compressor of a bus wherein the compressor is mounted on a platform connected to the transmission and wherein the compressor is belt driven from a power take-off connected to the transmission. The novel improvement comprises the structural combination of a built-in gauge pre-marked for range of adjustments for new and used belts and a single threaded rod extending through a threaded aperture and movable in a turn screw fashion against a side of the compressor via a pivoting engaging plate or cup, the plate or cup being made of high tensile strength steel capable of receiving at least several multiples of 240 pounds per square inch of pressure at any single point of engagement of the rod with the pivoting base of the plate or cup. The novel method is a significant improvement over the prior art method by eliminating the prior art structure and steps of having to adjust a plurality of rods, namely two side by side parallel rods, both separately and independently engaging the compressor with a non-swiveling engagement contact protrusion. In the prior art, each of the plurality of rods engages the compressor without the advantage or benefit of a built-in gauge pre-marked for range of adjustments for new and used belts. The two rods when independently adjusted tend to unevenly adjust or catercorner the compressor position on the mounting plate in relationship to the plane of the compressor belt. Whereas, the novel improved structure comprising one rod and an engaging swivelable faceplate juxtaposed against an orthogonal wall or surface of the compressor substantially diminishes catercornering. In the novel adjustment method, the inherent elasticity of the belt and compressor assembly is utilized to press a face of the compressor evenly against the swiveling faceplate, thereby evenly distributing the tension from the belt against the faceplate. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings wherein:  
         [0022]    [0022]FIG. 1 is a detailed perspective view showing the prior art assembly and method for adjusting the tension of a belt connected to a compressor by moving the compressor.  
         [0023]    [0023]FIG. 2 is a detailed perspective view showing the novel and improved assembly and novel method for adjusting the tension of a belt connected to a compressor by moving the compressor.  
         [0024]    [0024]FIG. 3 is a detailed top view of the novel improved push block assembly for adjusting the tension of a belt connected to a compressor in a bus.  
         [0025]    [0025]FIG. 4 is a detailed rear view of the novel improved push block assembly.  
         [0026]    [0026]FIG. 5 is a detailed bottom view of the novel improved push block assembly.  
         [0027]    [0027]FIG. 6 is a front view of the novel improved push block assembly.  
         [0028]    [0028]FIG. 7 is a perspective view of the novel improved push block assembly showing details of the presets on a tension gauge pin assembly. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0029]    The present invention will be described hereinafter with reference to the accompanying drawings which illustrate a preferred embodiment of the invention.  
         [0030]    Shown in FIG. 1 is an example of the prior art. This invention as illustrated in the remaining figures presents several novel improvements over the prior art including eliminating a push rod, using a swivelable flat push block and bracket assembly that, during tension adjustments, uses the elasticity of the tensioned belt to force the block flat against the compressor, and using preset markings on a gauge to set the compressor for new and/or used belts.  
         [0031]    There in FIG. 1 is shown an assembly  10  of a bus refrigerant or air conditioning compressor  12  mounted on a plate  14  via a plurality of mount bolt and nut sets  16 . The plate  14  is fashioned with a plurality of strategically placed apertures  18  and  20  to facilitate attachment of other items to the plate  14  and vice versa. In the prior art a pair of push members  22  and  24  are used to push the compressor  12  away from the push members  22  and  24  by adjusting one push member forward toward the compressor  12  first, for example member  22 , and then by adjusting the other push member forward toward the compressor  12  next, for example member  24 .  
         [0032]    The compressor  12  is powered by a pulley (not shown) connected via a belt (not shown) connected to a pulley of a power take off or PTO (not shown) of a bus transmission (not shown). The purpose of the push members  22  and  24  is to adjust the tension on the belt connecting the PTO to the compressor  12  by pushing the compressor  12  away from the PTO.  
         [0033]    As shown for the prior art in FIG. 1, the push member  22  is mounted in a hole  23  in a mounting block  26  which vertically extends from the plate  14 . The push member  24  is mounted in a hole  25  in a mounting block  28  which vertically extends from the plate  14 , parallel to the mounting block  26 . The push members  22  and  24  are fixedly attached in the holes  23  and  25 , respectively, by means of nuts  30 ,  32 ,  34 , and  36  threadedly mounted on the respective push members  22  and  24  on each vertical face of each of the mounting blocks  26  and  28 , respectively.  
         [0034]    The push members  22  and  24  are made of threaded cylindrical rods  38  and  39 , respectively. In the cumbersome prior art arrangement, the rod  38  is mounted in the hole  25  with nuts  34  and  36 , which are screwed onto the rod  38 . Likewise, the rod  39  is mounted in the hole  23  with nuts  30  and  32 , which are screwed onto the rod  39 .  
         [0035]    An improved novel assembly  40  is shown in FIG. 2. The assembly  40  is improved by eliminating one of the push rods and thereby eliminating the steps of having to adjust two separate rods back and forth to achieve an even as compared to a cantered push on the compressor  12 . In the novel assembly  40  there is shown a push plate  44  connected to a marker device  46 . The marker device  46  is connected to a flange  42 . The flange  42  is made of two thick long parallel rectangular steel plates  42   a  and  42   b  spaced apart and interconnected by an orthogonal plate  42   c . A relatively smaller bracing plate  50  is shown connected to adjoining top edges of the plates  42   a ,  42   b , and  42   c.    
         [0036]    Shown in FIG. 3 is a nut  52  permanently and immovably attached to the plates  42   b  and  42   c . The nut  52  has an aperture  54   a  aligned with another aperture  54   b  formed in the plate  42   b . A bolt  56  threadedly extends through the nut  52  and connects to a push plate  44 . The push plate  44  is pushed by the bolt  56  against the compressor  12  and thereby adjusts the tension of a belt (not shown) connected to the compressor  12 . The push plate  44  is connected to the bolt  56  via nut and swivel assembly  58 .  
         [0037]    The push plate  44 , selected to several times larger (e.g. six times) in surface area than the cross-sectional area of the bolt  56 , houses a tension gauge  46  made of a rod or pin  60  with preset markings for specific tensions thereon. One end of the pin  60  extends into a cylinder  62  and is non-frictionally and slidably engaged in a horizontal aperture  64  located in the push plate  44 . Another end of the pin  60  extends into a cylindrical roll rod  66  set horizontally in the plate  42   c . The horizontal aperture  64  non-frictionally allows the pin  60  to slide or move in and out as tension on compressor  12  from the belt (not shown) is adjusted.  
         [0038]    Referring to FIG. 4, there the flange  42  made of the plate  42   b  is shown with apertures  72  therein for mounting onto the mounting block  28  (shown in FIG. 1). The plate  42   a  has apertures  74  for mounting onto the mounting block  26  (shown in FIG. 1). A bottom view of the flange  42  and push plate  44  as assembled is illustrated in FIG. 5. And in FIGS. 6 and 7 there is shown a frontal view of the flange  42  and push plate  44  with the aperture  64  for the pin  60 . The pin  60  functions as a tension gauge. The pin  60  is adapted with a plurality of preset markings  80  and  82 , for example, to indicate positions of the push block  44  corresponding to appropriate tensioning positions for belts (not shown): for example, belts A and B wherein belt B is a new belt first placed in service and belt B is a used belt in services for 600 hours.  
         [0039]    As this invention may be embodied in several forms and utilize each of many kinds of engaging cups or plates with any single rod or quantity adjustable vector force delivery system without departing from the spirit or essential characteristics thereof, the present embodiment is, therefore, illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalent steps are, therefore, intended to be embraced by those claims.  
       PARTS LIST  
       [0040]    [0040] 10  assembly  
         [0041]    [0041] 12  air conditioning compressor  
         [0042]    [0042] 14  plate  
         [0043]    [0043] 16  plurality of mount bolt and nut sets  
         [0044]    [0044] 18  first aperture  
         [0045]    [0045] 20  second aperture  
         [0046]    [0046] 22  first push member  
         [0047]    [0047] 24  second push member  
         [0048]    [0048] 23  hole  
         [0049]    [0049] 26  first mounting block  
         [0050]    [0050] 25  second hole  
         [0051]    [0051] 28  second mounting block  
         [0052]    [0052] 30  first nut  
         [0053]    [0053] 32  second nut  
         [0054]    [0054] 34  third nut  
         [0055]    [0055] 36  fourth nut  
         [0056]    [0056] 38  first cylindrical rod  
         [0057]    [0057] 39  second cylindrical rod  
         [0058]    [0058] 40  improved novel assembly  
         [0059]    [0059] 42  flange  
         [0060]    [0060] 42   a  rectangular steel plate  
         [0061]    [0061] 42   b  rectangular steel plate  
         [0062]    [0062] 42   c  orthogonal plate  
         [0063]    [0063] 44  singular push plate  
         [0064]    [0064] 46  tension gauge  
         [0065]    [0065] 50  bracing plate  
         [0066]    [0066] 52  fixed nut  
         [0067]    [0067] 54   a  aperture  
         [0068]    [0068] 54   b  aperture  
         [0069]    [0069] 56  bolt  
         [0070]    [0070] 58  nut and swivel assembly  
         [0071]    [0071] 60  pin  
         [0072]    [0072] 62  cylinder  
         [0073]    [0073] 64  horizontal aperture  
         [0074]    [0074] 66  cylindrical roll rod  
         [0075]    [0075] 72  first apertures  
         [0076]    [0076] 74  second apertures  
         [0077]    [0077] 80  preset marking  
         [0078]    [0078] 82  preset marking