Abstract:
An apparatus and method are provided for facilitating the cooling of engine coolant flowing through a radiator operatively connected to the engine of an engine-driven, electrical generator set. The engine has a crankshaft rotatable about a first axis and a radiator having a first side directed towards the engine and a second side. The apparatus includes a fan positionable on the second side of the radiator that is rotatable about a second axis generally parallel to and vertically spaced from the first axis. The apparatus includes a thermally responsive clutch having a driven portion. The clutch is movable between a first disengaged position wherein the driven portion is isolated from the crankshaft and a second engaged position wherein the driven portion rotates in unison with the crankshaft in response to a predetermined temperature. A fan drive system interconnects the driven portion of the clutch and the fan for translating rotation of the driven portion to the fan.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to engine-driven, electrical generators, and in particular, to an apparatus and method for cooling the engine coolant flowing through a radiator of an engine-driven, electrical generator.  
       BACKGROUND AND SUMMARY OF THE INVENTION  
       [0002]     Engine-driven, electrical generators are used in a wide variety of applications. Typically, such electrical generators utilize a single driving engine directly coupled to a generator or alternator through a common shaft. Upon actuation of the engine, the crankshaft thereof rotates the common shaft so as to drive the alternator which, in turn, generates electricity. It can be appreciated that since the engine and the alternator are housed in a single enclosure, a significant amount of heat is generated within the enclosure during operation of the electrical generator.  
         [0003]     Typically, prior electrical generators include radiators operatively connected to corresponding engines such that the engine coolant from the engines circulates through the radiators during operation of the engines. A fan, coupled to the crankshaft of the engine, rotates during operation of the electrical generator and draws air across the plurality of radiator tubes of the radiator so as to effectuate the heat exchange between the engine coolant flowing through the plurality of radiator tubes of the radiator and the air within the enclosure. In such a manner, it is intended that the air passing over the radiator tubes of the radiator having a cooling effect thereon so as to maintain the temperature of the engine coolant, and hence the temperature of the engine, below a safe operating limit.  
         [0004]     As is known, operation of an engine driven, electrical generator can produce unwanted noise. The noise generated by the electrical generator during operation is often a result of the rotation of the fan used to cool the engine coolant flowing through the radiator tubes of the radiator of the electrical generator. Consequently, various attempts have been made to limit the time period and the speed at which the fan rotates during operation of the electrical generator to those situations wherein the engine coolant flowing through the radiator must be cooled. By way of example, a sensor may be provided to monitor the temperature of the engine coolant. The fan is operatively connected to the crankshaft of the engine only when the temperature of the engine coolant exceeds a predetermined threshold. Alternatively, in automotive applications, the fan may be connected to the crankshaft by a thermally responsive clutch. The clutch directly connects the fan to the crankshaft of the engine when the air drawn through the radiator by the fan exceeds a predetermined temperature threshold.  
         [0005]     While these prior methods of minimizing the time period for rotating a fan of an engine-driven, electrical generator have been somewhat successful, each of these methods has significant limitations. By way of example, the use of a sensor and the associated electronics for selectively connecting the fan to the crankshaft of the engine can be cost prohibitive. Alternatively, by drawing air inward through the radiator as provided in various automotive applications, it has been found that the thermally responsive clutch interconnects the fan to the crankshaft at the engine for a longer period of time than is necessary to cool the engine coolant flowing through the radiator to a safe operating level. Hence, it can be appreciated that these prior art fan systems will generate more noise than necessary and/or desired by an end user.  
         [0006]     Therefore, it is a primary object and feature of the present invention to provide a method and apparatus for reducing the fan noise associated with the operation of an engine driven, electrical generator.  
         [0007]     It is a further object and feature of the present invention to provide a method and apparatus for reducing the fan noise associated with the operation of an engine driven, electrical generator that is simple and inexpensive to implement.  
         [0008]     It is a still further object and feature of the present invention to provide a method and apparatus for reducing the fan noise associated with the operation of an engine driven, electrical generator that sufficiently cools the engine coolant flowing through the radiator of the electrical generator with the fan.  
         [0009]     It is a still further object and feature of the present invention to provide a method and apparatus for sufficiently cooling the engine coolant flowing through the radiator of an engine for an engine-driven, electrical generator set that is adaptable for use with engines of different sizes.  
         [0010]     In accordance with the present invention, a fan assembly is provided. The fan assembly is connectable to the crankshaft of an engine for facilitating the cooling of engine coolant flowing through a radiator. The radiator has a first side directed toward the engine and a second side. The fan assembly includes a rotatable fan positionable on the second side of the radiator. A driven pulley is operatively connected to the fan for rotational movement therewith. The fan assembly further includes a rotatable drive pulley and a fan belt system extending about the drive pulley and the driven pulley. The fan belt system translates rotation of the drive pulley to the fan. A fan clutch is also provided. The fan clutch is movable between a first disengaged position wherein the drive pulley is isolated from the crankshaft and a second engaged position wherein the fan clutch translates rotation of the crankshaft to the drive pulley in response to a predetermined temperature. The fan belt system includes a fan belt having a tension. The fan belt extends about the drive pulley and the driven pulley. The fan belt system also includes a rotatable take-up pulley. The take-up pulley is movable in order to adjust the tension of the fan belt to a user desired level.  
         [0011]     The fan is oriented to pull air through the radiator from the first side to the second side thereof in response to rotation of the fan in a first direction. A housing element is positioned on the second side of the radiator. The housing element directs the air pulled through the radiator by the fan towards the fan clutch. The fan clutch includes a bi-metallic element for sensing the temperature of the air directed towards the fan clutch by the housing element.  
         [0012]     In accordance with a further aspect of the present invention, a device is provided for cooling engine coolant flowing through a radiator of an engine-driven, electrical generator set. The engine has a crankshaft rotatable about a first axis and the radiator has a first side directed towards the engine and a second side. The device includes a fan positionable on the second side of the radiator. The fan is rotatable about a second axis generally parallel to the first axis. A thermally responsive clutch having a driven portion is also provided. The clutch is movable between a first disengaged position wherein the driven portion is isolated from the crankshaft and a second engaged position wherein the driven portion rotates in unison with the crankshaft in response to a predetermined temperature. A fan drive system interconnects and translates rotation of the driven portion of the clutch to the fan.  
         [0013]     The fan drive system includes a driven pulley operatively connected to the fan for rotational movement therewith. In addition, the fan drive system includes a rotatable drive pulley and a fan belt. The rotatable drive pulley is operatively connected to the driven portion of the clutch for rotational movement therewith. The fan belt extends about the drive pulley and the driven pulley to translate rotation of the drive pulley to the driven pulley. A rotatable take-up pulley is provided to adjust the tension of the fan belt to a user-desired level.  
         [0014]     It is contemplated for the fan to be orientated to pull air through the radiator from the first side to the second side of the radiator in response to rotation of the fan in a first direction. A housing element is positioned on the second side of the radiator to direct the air pulled through the radiator by the fan towards the clutch. The clutch includes a temperature sensing element for sensing the temperature of the air directed towards the clutch by the housing element.  
         [0015]     In accordance with a still further aspect of the present invention, a method is provided for cooling engine coolant flowing through a radiator of an engine-driven, electrical generator set. The engine has a crankshaft rotatable about a first axis and the radiator has a first side directed towards the engine and a second side. The method includes the steps of positioning the fan on the second side of the radiator and monitoring the temperature on the second side of the radiator. The fan is rotatable about a second axis generally parallel to the first axis for drawing air through the radiator. The fan is operatively connected to the crankshaft in response to the temperature of the air on the second side of the radiator exceeding a threshold.  
         [0016]     The fan is supported on a rotatable shaft having a driven pulley attached thereto. The driven pulley includes a groove formed therein. A drive pulley is also provided having a groove formed therein. A fan belt is positioned about the groove in the drive pulley and the groove in the driven pulley such that rotation of the drive pulley is translated to the driven pulley by the fan belt. The drive pulley is interconnected to a thermally responsive clutch. The clutch is movable between a first disengagement position wherein the drive pulley is isolated from the crankshaft and a second engaged position wherein the clutch translates rotation of the crankshaft to the drive pulley in response to the predetermined temperature. It is contemplated to disconnect the fan from the crankshaft in response to the temperature of the air on the second side of the radiator dropping below the threshold. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The drawings furnished herewith illustrate a preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiment.  
         [0018]     In the drawings:  
         [0019]      FIG. 1  is an end view of a fan drive system for an engine-driven, electrical generator set in accordance with the present invention; and  
         [0020]      FIG. 2  is a cross-sectional view of the fan drive system of the present invention taken along line  2 - 2  of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring to  FIGS. 1 and 2 , a fan drive assembly in accordance with the present invention is generally designated by the reference numeral  10 . It is intended for fan drive assembly  10  to be used in connection with engine-driven, electrical generator set  11 . As is conventional, generator set  11  is housed in enclosure  12  defined by first and second sidewalls  14  and  16 , respectively, interconnected by a first forward end wall (not pictured) and a second rear end wall  18 . Sidewalls  14  and  16  define interior  20  of enclosure  12 . Base  24  of enclosure  12  is provided for supporting generator set  11  above a supporting surface  26  such as the ground, concrete slab or a mounting pad.  
         [0022]     Generator set  11  includes an engine, generally designated by the reference numeral  30 , which is supported within interior  20  of enclosure  12 . As is conventional, engine  30  receives fuel such as diesel, natural gas or liquid propane vapor through an intake. The fuel is compressed and ignited within the cylinders of engine  30  so as to generate reciprocating motion of the pistons of engine  30 . This reciprocating motion of the pistons of engine  30  is converted to rotary motion such that engine  30  rotates a drive or crankshaft  32  about a first horizontal axis. Crankshaft  32  of engine  30  is coupled to fan shaft  34  through flexible coupling hub  36  and flex plate  38 .  
         [0023]     Engine  30  is operatively connected to radiator  40  such that coolant from engine  30  circulates through radiator  40  during operation of engine  30 . As is conventional, radiator  40  includes a plurality of radiator tubes (not shown) through which engine coolant flows. As hereinafter described, it is intended for air within interior  20  of enclosure  12  pass over the plurality of radiator tubes of radiator  40  so as to effectuate a heat exchange between the engine coolant flowing through the plurality of radiator tubes of radiator  40  and the air within interior  20  of enclosure  12  in order to cool the engine coolant.  
         [0024]     Radiator  40  is supported within interior  20  of enclosure  12  by radiator support  42 . Radiator support  42  acts as a partition to separate interior  20  of enclosure  12  into a first engine receiving portion  46  for receiving engine  30  and radiator  40  therein and a second clutch receiving portion  48 . Radiator support  42  further includes generally circular fan opening  50  therethrough for allowing communication between first portion  46  and second portion  48  of interior  20  of enclosure  12 . Generally horizontal support  52  bisects fan opening  50  and includes generally flat upper surface  54 . Fan support tube  56  is mounted to upper surface  54  and includes passageway  56   a  extending therethrough along a second generally horizontal axis, axially spaced from and generally parallel to the first horizontal axis, for reasons hereafter described.  
         [0025]     In order to draw air over the plurality of radiator tubes of radiator  40 , fan  58  is provided in opening  50  through radiator support  42 . Fan  58  includes a plurality of fan blades  60  extending radially from central hub  62 . Central hub  62  is operatively connected to fan shaft  64  which is rotatably supported within passageway  56   a  of fan support  56 . Fan pulley  68  is captured between fan shaft  64  and central hub  62  of fan  58  for rotational movement therewith. Fan pulley  68  includes a radially outer edge  68   a  having generally V-shaped groove  70  formed therein that is adapted for receiving fan belt  72 , as hereinafter described.  
         [0026]     As best seen in  FIG. 2 , fan shaft  34  includes terminal end  34   a  interconnected to drive portion  75  of thermally responsive fan clutch  76  by bolts  78 . Jackshaft  34  extends through opening  80  in radiator support  42 ; through central opening  82   a  in bearing  82  and through central opening  84   a  in bearing  84 . Bearing  82  is interconnected to radiator support  42  by a plurality of bolts  86  such that central opening  82   a  therethrough is axially aligned with opening  80  through radiator support  42 . Bearing  84  is received within central opening  88   a  of drive pulley  88 .  
         [0027]     Drive pulley  88  includes V-shaped groove  90  in outer periphery thereof adapted for receiving fan belt  72 . Drive pulley  88  is interconnected to driven portion  93  of fan clutch  76  by a plurality of bolts  94 . Fan clutch  76  is preferably a viscous fan drive that includes a bi-metallic temperature sensing element  96 . Temperature sensing element  96  causes fan clutch  76  to operate in a disengaged position wherein drive portion  75  and driven portion  93  of fan clutch  76  are isolated from each other when the ambient air temperature sensed is below a predetermined temperature and to operate in an engaged position wherein rotation of drive portion  75  of fan clutch  76  is translated to driven portion  93  of fan clutch  76  when the ambient air temperature sensed above a predetermined temperature. More specifically, in its engaged position, fan clutch  76  operatively connects drive portion  75  of fan clutch  76  to driven portion  93  such that rotation of fan shaft  34  by crankshaft  32  of engine  30  is translated to drive pulley  88  which, in turn, rotates fan pulley  68  through fan belt  72 . Fan pulley  68 , in turn, rotates fan  58  about the second horizontal axis extending through passageway  56   a  of fan support tube  56 . It can appreciated that in its engaged position, fan clutch  76  may be fully or partially engaged. With fan clutch  76  in its fully engaged position, rotation of crankshaft  32  is translated to drive pulley  88  through jackshaft  34  and fan clutch  76 . In its partially engaged condition, clutch  76  allows driven portion  93  of fan clutch  76  to slip with respect to drive portion  75  of fan clutch  76  such that drive pulley  88  rotates at a speed less than the speed of rotation of crankshaft  32 . As such, it can be understood that fan clutch  76  causes drive pulley  88  to rotate a variable speed dependent upon the ambient temperature sensed by temperature sensing element  96 . With fan clutch  76  in its disengaged position, jackshaft  34  rotates independently of drive pulley  88 .  
         [0028]     It is contemplated to vary the diameters of drive pulley  88  and fan pulley  68  to vary the rotational speed of fan  58  for a given, constant rotational speed of crankshaft  32  of engine  30 . More specifically, by reducing the diameter of fan pulley  68  with respect to the diameter of drive pulley  88 , the rotational speed of fan  58  can be increased with respect to the rotational speed of crankshaft  32 . Alternatively, if the diameter of fan pulley  68  is larger than the diameter of drive pulley  88 , the rotational speed of fan  58  can be decreased with respect to the rotational speed of crankshaft  32 . Finally, if the diameter of fan pulley  68  is identical to the diameter of drive pulley  88 , the rotational speed of fan  58  will be identical to the rotational speed of crankshaft  32 . As a result, fan drive assembly  10  allows for the use of a smaller rated clutch and still provide adequate rotational fan speed to cool the engine coolant flowing through radiator  40 .  
         [0029]     In order to maintain the tension on fan belt  72 , take-up pulley assembly, generally designated by the reference numeral  100 , is provided. Take-up pulley assembly  100  includes take-up pulley  102  having V-shaped groove  104  in the outer periphery thereof. V-shaped groove  104  is adapted for receiving fan belt  72 . The hub of take-up pulley  102  is rotatably connected to first end  108   a  of tension arm  108  by nut and bolt combination  110 . Second end  108   b  of tension arm  108  is pivotably connected to flange  112  depending from support  52  by nut and bolt combination  114 . A tension spring  116  interconnects tension arm  108  to support  52  so as to urge take-up pulley  102  towards support  52  in a clockwise direction. The tension of spring  116  corresponds to the tension placed on fan belt  72  by take-up pulley  102 .  
         [0030]     In operation, generator set  11  is activated so as to start engine  30 . As is conventional, engine  30  drives an alternator (not shown) which, in turn, generates electricity. Once started, engine  30  rotates crankshaft  32 , and hence, fan shaft  34  about the first horizontal axis. With fan clutch  76  in its disengaged position, drive portion  75  of fan clutch  76  rotates independently of driven portion  93  of fan clutch  76 . When the temperature sensed by temperature sensing element  96  exceeds a predetermined threshold, fan clutch  76  moves to its engaged position wherein fan clutch  76  either partially or fully interconnects drive portion  75  of fan clutch  76  to driven portion  93  of fan clutch  76  such that rotation of drive portion  75  is translated either, partially or fully, to driven portion  93  of fan clutch  76 , as heretofore described.  
         [0031]     With fan clutch  76  in its engaged position, the rotation of jackshaft  34  by crankshaft  32  of engine  30  is translated to drive pulley  88  interconnected to driven portion  93  of fan clutch  76  which, in turn, rotates fan pulley  68  through fan belt  72 . Fan pulley  68 , in turn, rotates fan  58  about the second horizontal axis in the first direction so as to draw air through radiator  40 . It can be appreciated that the air drawn through radiator  40  effectuates a heat exchange with the engine coolant flowing through the plurality of radiator tubes of radiator  40 . In addition, fan  58  draws air from first portion  46  of interior  20  of enclosure  12  and urges such air into second portion  48  of interior  20  of enclosure  12 . Rear end wall  18  of enclosure  12  directs the air urged into second portion  48  of interior  20  of enclosure  12  downwardly within second portion  48  of interior  20  of enclosure  12  toward fan clutch  76 . When the temperature sensed by temperature sensing element  96  drops below a predetermined threshold temperature, fan clutch  76  moves to its disengaged position, as heretofore described. In its disengaged position, fan  58  is isolated from crankshaft  32 . As engine  30  continues to operate, the process is repeated whereby temperature sensing element  96  moves fan clutch  76  between its disengaged and engaged positions in response to the temperature sensed by temperature sensing element  96 .  
         [0032]     Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing and distinctly claiming the subject matter which is regarded as the invention.