FIELD OF THE INVENTION
The present invention relates in general to air compressors and more specifically to an apparatus and method for cooling a compressor of a portable air compressor.
BACKGROUND OF THE INVENTION
Air compressors normally provide a source of pressurized air which is temporarily stored under pressure in a tank. A motor, typically an electric motor or a combustion engine, is connected to a compressor unit. The compressor unit typically includes a piston assembly having a piston slidably mounted in a cylinder, the piston compressing air from the atmosphere and forcing it into the fluid pressure tank for temporary storage. The work involved in compressing atmospheric air and the friction of the moving piston within the cylinder generate heat which must be dissipated. Cooling fins are commonly provided on the cylinder for air near the cylinder to convectively cool the piston assembly. Fans are also known which force air toward and about the piston assembly to increase convective cooling.
Several drawbacks exist for common portable air compressor cooling assemblies. One drawback is that common cooling configurations may not supply dedicated cooling air to the head area of the compressor. Another drawback is that common cooling configurations have duct portions that extend over the head area of the compressor. This can trap heat in the head area after the unit is turned off. Another drawback with some current compressor cooling designs is that only a single fan is used and the air ducting configuration(s) is are not optimized to control the distribution of all the air flow. It is therefore desirable to provide a cooling device for a portable air compressor assembly which overcomes the drawbacks of known air compressor assemblies.
SUMMARY OF THE INVENTION
In one preferred embodiment of the present invention, a cooling arrangement for a portable air compressor includes a portable air compressor air ducting device having a two-piece ducted fan blade cover. A first piece of the ducted cover includes a first air passage portion. A second piece of the ducted cover is adapted to connect to the first piece. The second piece has a second air passage portion adapted to align with the first air passage portion. An enclosed air passage is created between the first and second air passage portions when the first and second pieces are connected together. A grill area in the second piece of the ducted cover has a plurality of elongated apertures operable to deliver an air flow to the enclosed air passage.
In another preferred embodiment, a portable air compressor system includes a drive unit having a drive shaft. A first fan mounted to the drive shaft generates a first air flow. A compressor includes a driven shaft, a compressor head and a body. A second fan mounted to the driven shaft creates a second air flow directable toward the compressor body. A ducted fan cover at least partially encloses both the first and second fans. An air passage created in the fan cover transfers the first air flow from the first fan to the compressor head.
In yet another preferred embodiment, a portable air compressor assembly includes a tubular frame having side sections and an assembly longitudinal axis. A support plate between the side sections supports a power unit having a longitudinal axis arranged perpendicular to the assembly longitudinal axis. A compressor having a compressor head and longitudinal axis is mounted to the support plate with the compressor longitudinal axis parallel to the power unit longitudinal axis and perpendicular to the assembly longitudinal axis. A fan connected to the power unit generates an air flow. A ducted cover enclosing the fan includes an air passage directing the air flow from the fan to the compressor head. The ducted cover includes inner and outer covers each including a portion of the air passage. An air scoop extends into the outer cover portion of the air passage to redirect the air flow.
In still yet another preferred embodiment, a method for cooling a compressor of a portable air compressor assembly is provided. The air compressor assembly includes a power unit, a compressor having a body and a head area, a first fan mounted to the compressor, a second fan mounted to the power unit, and a ducted cover for protectively covering the first and second fans, the ducted cover having a ducted cavity and first and second grill areas. The method includes drawing a first air flow through the first grill area of the ducted cover using the first fan. A second air flow through the second grill area is generated using the second fan. The second air flow is directed through the ducted cavity formed within the ducted cover. The second air flow is redirected approximately 90 degrees using an opposed pair of radially curving walls of the ducted cover. The second air flow is then discharged adjacent to the head area of the compressor.
A cooling arrangement for a portable air compressor of the present invention offers several advantages. By aligning the longitudinal centerlines of both a compressor and a power unit parallel with each other and substantially perpendicular to a longitudinal axis of the air compressor, a compact arrangement of the components results. By providing two fans, a first driven by the compressor shaft and a second driven by the power unit shaft, increased cooling flow can be provided to the compressor. A ducted cover of the two fans allows for air intake through the cover and provides ducting to direct a substantially constant air flow from the power unit driven fan toward a head area of the compressor. An opposed pair of curved walls and an adapted air scoop within the ducting path smoothly transition the air approximately 90 degrees to discharge toward the compressor head area. Duct portions are provided in each of two halves of the ducted cover to provide defined duct segments which efficiently distribute the air flow and smoothly transition toward a discharge end.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is a perspective view of a preferred embodiment for an air compressor assembly having a cooling arrangement for a portable air compressor of the present invention;
FIG. 2 is a plan view of the assembly of FIG. 1;
FIG. 3 is a side elevation view taken along Section 3 of FIG. 2;
FIG. 4 is a side elevation view taken along Section 4 of FIG. 2;
FIG. 5 is a side perspective view looking inward of a cooling jacket of the present invention;
FIG. 6 is a side perspective view looking outward of a cooling shroud of the present invention;
FIG. 7 is a partial cross sectional view taken at Section 7 of FIG. 6 showing a transitional region of the cooling jacket;
FIG. 8 is a partial perspective view showing the geometry of the exhaust area of the cooling jacket;
FIG. 9 is a plan view of another preferred embodiment of an air compressor assembly having a cooling arrangement for a portable air compressor of the present invention; and
FIG. 10 is a flow diagram presenting the operations of a method for cooling a compressor assembly of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
FIG. 1 identifies an air compressor assembly 10 according to one preferred embodiment of the present invention. The air compressor assembly 10 includes a frame 12, a component group 14, and a pressurized fluid containment tank 16. A first wheel 18 and a second wheel 20 are rotatably supported from the frame 12 at an aft end of the air compressor assembly 10. The frame 12 includes a first side 22 and a second side 24. The first side 22 and the second side 24 are generally tubular shaped frame members substantially formed in a parallelogram configuration having rounded corners. A support plate 26 is provided at a lower portion of the frame 12 and is mechanically joined to the first side 22 and the second side 24, respectively. A pair of support feet 28 are mechanically joined to a forward end of the frame 12 at an under surface of the support plate 26. Frame 12 is more specifically described in U.S. patent application Ser. No. 10/392,567, filed Mar. 20, 2003, the subject matter of which is incorporated herein by reference.
Each of the support feet 28 includes an elastomeric pad 30 (only one is visible in FIG. 1). The purpose of elastomeric pads 30 is to reduce a sliding motion of air compressor assembly 10 when the compressor is operating and to prevent the unit from sliding when placed on a relatively smooth surface. A control panel 32 is provided on either the first side 22 or the second side 24. Control panel 32 provides pressure gauges, control switches, hose connections, etc. which are commonly available on air compressor assemblies and will therefore not be further described herein. A rear support member 34 is provided to structurally join the first side 22 to the second side 24. In one preferred embodiment, the rear support member 34 and the support plate 26 are each welded to the first side 22 and the second side 24. In the embodiment shown, the control panel 32 is connected to an upper member 35 and a lower member 36 of the second side 24.
FIG. 1 also shows a handle 38 which is connected to the forward end of frame 12 and used to manually push/pull air compressor assembly 10. In the position shown, handle 38 is retracted for shipping or storage. Handle 38 is re-positionable to an extended position 38′ in the direction of arrow “A” for manually pushing/pulling air compressor assembly 10. Frame 12 is connected to an upper portion of fluid tank 16 using first and second brackets 40, 42 each having a flange 44 connected to fluid tank 16 for example by welding, and connected to frame 12 using fasteners 46.
As best seen in FIG. 2, in one preferred embodiment component group 14 includes a power unit 48 which drives a compressor 50. In the embodiment shown, power unit 48 is an electric motor, however, the invention is not limited to electric motors. Power unit 48 can be any type of rotating power delivery device including but not limited to gasoline or alternate fuel engines. Compressor 50 delivers compressed air to fluid tank 16. A longitudinal axis 52 of power unit 48 and a longitudinal axis 54 of the compressor 50 are arranged substantially perpendicular to an air compressor assembly longitudinal axis 56. An output shaft 58 of power unit 48 is co-axially aligned with longitudinal axis 52. A driven or input shaft of compressor 50 (not visible in FIG. 2) is co-axially aligned with longitudinal axis 54. The locations of the power unit 48, the compressor 50, and the fluid tank 16 are selected to generally evenly distribute the weight of these components about the air compressor assembly longitudinal axis 56 and to functionally connect the components. The power unit 48 and the compressor 50 are also completely contained within an envelope of frame 12 and specifically contained within a width “B” of frame 12. Wheel 20 is not shown in FIG. 2 so that one of a pair of mounting shafts 59 used to rotatably mount first and second wheels 18, 20 to frame 12 is visible.
FIG. 2 further shows a two-piece ducted cover 60 which provides a protective guard for cooling fans connected to both power unit 48 and compressor 50. Ducted cover 60 further functions to direct cooling air within ducted cover 60 in the general direction of flow arrow “C” and discharges the cooling air in the general direction of flow arrow “D”. Discharged cooling air is directed at and above a compressor cooling head 61 of compressor 50. Discharged cooling air in the direction of flow arrow “D” is directed substantially perpendicular to the direction of flow (flow arrow “C”) within ducted cover 60. In a preferred embodiment of the present invention, ducted cover 60 is manufactured from a polymeric material and is retained within frame width “B” of frame 12 to help prevent damage to ducted cover 60.
Referring to FIG. 3, ducted cover 60 is positioned within a vertical envelope “E” between upper member 35 and lower member 36 of frame 12 and within a fore/aft envelope “F” of frame 12. An outer facing member or first portion 62 of ducted cover 60 includes a first grill area 64 and a second grill area 66 for drawing air toward the power unit 48 and compressor 50 respectively, (into the page as viewed in FIG. 3). Each of first and second grill areas 64, 66 include a plurality of substantially parallel elongated apertures 68, 70 respectively. In the embodiment shown, elongated apertures 68 of first grill area 64 form a rectangular-shaped grill and elongated apertures 70 of second grill area 66 form a circular-shaped grill. The invention is not limited to any particular geometric shape for first or second grill areas 64, 66. Outer facing first portion 62 of ducted cover 60 can also include one or more indicia areas 72 to provide for example a manufacturer's name or other identifying information.
Referring to both FIGS. 3 and 4, a first fan 74 directly connected to an input or driven shaft 76 of compressor 50 and rotating in a rotation direction “G” forces a first air flow of air drawn through first grill area 64 of ducted cover 60 through an inlet grill 78 created in an inner facing member or second portion 80 of ducted cover 60. The air discharged through inlet grill 78 is directed toward an outer body of compressor 50. To provide additional cooling air to the head 61 of compressor 50, a second fan 82 directly mounted to output shaft 58 of power unit 48 rotating in a rotation direction “H” delivers a second air flow drawn through second grill area 66 into a receiving plenum 84 of ducted cover 60. From receiving plenum 84, the second air flow is directed via an inner duct wall 84 and an outer duct wall 86 into a transition region 90 and then redirected approximately 90 degrees (away from the viewer) into a discharge area 92 for discharge toward the compressor head 61. In one preferred embodiment of the present invention, second fan 82 is a radial flow fan.
As best seen in reference to FIG. 5, second portion 80 of ducted cover 60 is connected to support plate 26 using a plurality of fastener mounting brackets 94 connected to second portion 80, and preferably molded together with second portion 80. Air drawn in a direction of a first air flow indicated by an arrow “J” through first grill area 64 is generally maintained in the direction of first air flow arrow “J” as it is distributed toward a plurality of cooling fins 96 disposed on a body 98 of compressor 50. Air initially drawn in a direction of a second air flow indicated by an arrow “K” through second grill area 66 is redirected approximately 90 degrees by a plurality of radially mounted, fan blades 100 of rotating second fan 82 and distributed into receiving plenum 84. Transition region 90 of second portion 80 further includes a smoothly outwardly curving wall 102 which transitions the second air flow into discharge area 92. A radially curving wall 104 forming a distal end of discharge area 92 smoothly transitions the second air flow entering discharge area 92 from transition region 90 to redirect the second air flow from second fan 82 approximately 90 degrees and toward compressor head 61. As also clearly seen in FIG. 5, first portion 62 of ducted cover 60 is generally outwardly located with respect to second fan 82 and second portion 80 of ducted cover 60 is generally inwardly located (positioned toward power unit 48) with respect to second fan 82. Ducted cover 60 therefore encompasses second fan 82 (as well as first fan 74) when first portion 62 is connected to second portion 80.
As generally shown in FIG. 6, the outer facing first portion 62 includes an outer sealing edge 106 which aligns and mates with an outer sealing edge 108 of second portion 80 of ducted cover 60. First portion 62 is joined to second portion 80 using a plurality of fasteners 110 which each slidably fit within a clearance aperture 112 of a plurality of extended elements 114 positioned about a perimeter of outer facing first portion 62. Fasteners 110 engage with each of a plurality of mating elements 116 provided with second portion 80, each aligned with one of the extended elements 114.
A plurality of dividing walls 118 separate individual pairs of elongated apertures 70 of second grill area 66. Air entering each of the elongated apertures 70 is collected within an increasing radius (for example a nautilus-shaped) boundary wall 120 which is positioned to closely rotatably clear a perimeter of second fan 82 and direct substantially all of the second air flow received through elongated apertures 70 into a receiving area 122 bounded by boundary wall 120. Boundary wall 120 extends approximately perpendicular to first portion 62. From receiving area 122, second fan 82 directs the second air flow into a receiving plenum 124, similar to receiving plenum 84 of second portion 80. From receiving plenum 124, the air is directed into a transition region 126 having a substantially constant total cross-section. The total cross-section is maintained to stabilize the air flow and at least maintain its velocity. Transition region 126 is shaped similarly to transition region 90 of second portion 80. The ducting formed by receiving plenum 124 and transition region 126 is bounded by an inner duct wall 128 and an outer duct wall 130 which direct the second air flow into a discharge transition area 132.
Second portion 80 further includes one or more stiffening members 134 and an air scoop 135 having a scoop wall 136. Scoop wall 136 abuts against a flow containment wall 138 of first portion 62 when the two ducted cover halves, first and second portions 62, 80, respectively, are connected. Scoop wall 136 transitions into radially curving wall 104 to direct substantially all the second air flow within discharge transition area 132 of first portion 62 and discharge area 92 of second portion 80 through a discharge opening 139.
Referring next to FIGS. 7 and 8, a butted perimeter joint 140 is created when first portion 62 and second portion 80 are connected. A gasket or sealant (not shown) is not required to seal perimeter joint. 140, but can optionally be used. The cross sectional view through the discharge transition area 132 of first portion 62 and discharge area 92 of second portion 80 identifies a transition wall 142 created at a lower portion of first portion 62 having a wall thickness “L” generally greater than a wall thickness “M” of discharge area 92. The increased thickness of wall thickness “L” provides a substantially flush alignment between a raised surface 144 and a mating inner surface 146 of air scoop 135. An extended duct portion 148 is also provided as necessary from an upper surface 150 of discharge area 92. Extended duct portion 148 conforms to the shape of a plurality of cooling fins 152 on an upper surface of compressor head 61. A plurality of elongated apertures 154 are defined by a plurality of dividing walls 156 created in inlet grill 78 for flow of air. In one preferred embodiment, extended duct portion 148 and upper surface 150 do not extend vertically over cooling fins 152 of compressor head 61 so that vertical thermal cooling of compressor head 61 is not blocked. A clearance dimension “N” is therefore maintained between upper surface 150 (including extended duct portion 148) and compressor head 61. In an alternate embodiment of the present invention (not shown), extended duct portion 148 and upper surface 150 extend at least partially over cooling fins 152 of compressor head 61.
As best seen in FIG. 7, when first and second portions 62 and 80 of ducted cover 60 are connected, an enclosed air passage 143 is created. In one preferred embodiment, enclosed air passage 143 is substantially rectangular-shaped. Each of an opposed pair of portions 143′, 143″ of enclosed air passage 143 provided by first and second portions 62, 80, respectively, can be equivalent in cross-sectional area (not shown) or can vary in cross-sectional area (as shown in FIG. 7). In one preferred embodiment, each of the opposed portions 143′, 143″ of enclosed air passage 143 provided by first and second portions 62, 80 are substantially U-shaped and therefore when aligned with each other form a substantially rectangular-shaped enclosed air passage 143. The U-shaped portions 143′, 143″ and the rectangular-shaped enclosed air passage 143 are exemplary only, and the invention is not limited to these shapes. For example, each portion 143′, 143″ can be semi-square, semi-circular or semi-oval providing a square, circular or oval shape for enclosed air passage 143.
Referring now to FIG. 9, in another preferred embodiment of the present invention, a gasoline piston engine is used for power unit 48. Handle 38 of FIG. 1 is replaced by individual rounded handle ends 158, 160 on each of the first side 22 and the second side 24 of frame 12, respectively. A pair of handle brackets 162 are connected to the first side 22 and the second side 24, respectively and coupled by each of a pair of fasteners to a pair of tank brackets 164 each welded to the fluid tank 16. A first belt wheel 166 is mounted on an engine shaft 168 together with second fan 82. A second belt wheel 170 is mounted to driven shaft 76 of compressor 50. At least one “V” or drive belt 171 (only partially shown for clarity) is connected between first and second belt wheels 166, 170 to drive compressor 50 using power unit 48. First fan 74 and ducted cover 60 are not shown in FIG. 9 for clarity.
Referring finally to FIG. 10, method steps for cooling a compressor assembly of the present invention are described. In an initial operation 200, a first air flow is drawn into a first grill area of a ducted cover using a first fan and directed toward a compressor body. In a next operation 202, a second air flow is drawn into a second grill area by a second fan and directed into ducting formed within the ducted cover. In a following operation 204, the second air flow is directed into a transition region of the ducted cover having a defined cross-section sized to maintain a substantially constant second air flow velocity. In a next operation 206, the second air flow is redirected approximately 90 degrees by an opposed pair of smoothly curving walls. In a final operation 208, the second air flow is discharged adjacent to a head area of the compressor.
A cooling arrangement for a portable air compressor of the present invention offers several advantages. By aligning the longitudinal centerlines of both a compressor and a power unit parallel with each other and substantially perpendicular to a longitudinal axis of the air compressor, a compact arrangement of the components results. By providing two fans, a first driven by the compressor shaft and a second driven by the power unit shaft, increased cooling flow can be provided to the compressor. A ducted cover of the two fans allows for air intake through the cover and provides ducting to direct and maintain a substantially constant air flow from the power unit driven fan toward a head area of the compressor. An opposed pair of curved walls and an adapted air scoop within the ducting path smoothly transition the air approximately 90 degrees to discharge toward the compressor head area. Duct portions are provided in each of two halves of the ducted cover to provide defined duct segments which smoothly transition toward a discharge end.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
Patent Application
20060171820
