Patent Publication Number: US-2003235505-A1

Title: Vertical engine driven air compressor

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to air compressors, and particularly to engine driven air compressors. More particularly, the present invention relates to mobile engine driven air compressors.  
       [0002] Air compressors provide compressed air to operate air-powered tools at many types of facilities including construction sites, automobile repair facilities, and factories to name a few. In addition, air-powered equipment may be used in retail stores for displays or in any facility for maintenance duties. Many air compressors provide air for an entire facility and as such are quite large. These large compressors are permanently installed and powered by an electric motor. A system of accumulator tanks, distribution pipes, and manifolds transport the compressed air to points-of-use throughout the facility.  
       [0003] In some cases, a large air compressor is unnecessary. For example, home construction may require a compressor able to operate a single air-operated tool. In addition, a construction site may not have electrical power, thereby requiring a compressor driven by an internal combustion engine or other non-electrical prime mover. Furthermore, construction sites do not have elaborate air distribution systems, thus making it necessary to place high-pressure air hoses between the compressor and the desired point-of-use. A mobile compressor would minimize the quantity of hose required, thereby making for a more organized work site.  
       SUMMARY OF THE PREFERRED EMBODIMENT  
       [0004] The apparatus of the present invention provides an internal combustion engine including an engine housing and a shaft extending vertically out of the engine housing. The engine is operable to rotate the shaft. The apparatus further includes an air compressor having a compressor housing, a drive member, an air intake, and an air outlet. The drive member connects to the engine shaft along a vertical axis and is rotatable in response to rotation of the engine shaft. The air compressor draws in low-pressure air through the air intake and discharges a flow of high-pressure air through the air outlet in response to rotation of the drive shaft. The apparatus also includes an accumulator tank that receives the flow of high-pressure air from the air outlet.  
       [0005] In preferred embodiments, the engine is a lawnmower engine including a mounting flange having a standard bolt pattern. The flange facilitates attachment of the engine to the air compressor housing. Of course, other mounting arrangements may be used.  
       [0006] In another construction, the apparatus provides a frame, a plurality of wheels supporting the frame, and an internal combustion engine supported by the frame. The engine includes an engine housing and a vertical shaft extending out of the engine housing. The engine is operable to rotate the shaft. The apparatus further includes an air compressor supported by the frame, the air compressor having a compressor housing, a drive member, an air intake, and an air outlet. The drive member is connected to the engine shaft and is rotatable in response to rotation of the engine shaft. The air compressor draws in low-pressure air through the air intake and discharges a flow of high-pressure air through the air outlet in response to rotation of the drive member. The apparatus also includes an accumulator tank receiving the flow of high-pressure air from the air outlet.  
       [0007] The invention also provides a method of assembling a mobile high-pressure air supply apparatus including a frame having a handle and an axle, a plurality of wheels, an internal combustion engine having a vertical drive shaft, an air compressor, and an accumulator tank. The method comprises the steps of attaching the plurality of wheels to the axle, attaching the air compressor to the frame, and providing a drive member connected to the air compressor and engagable with the engine drive shaft. The method also includes the steps of aligning the engine drive shaft vertically with the drive member, engaging the drive member and the engine shaft, attaching the engine to the frame, and attaching the accumulator tank to the frame. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] The detailed description particularly refers to the accompanying figures in which:  
     [0009]FIG. 1 is a perspective view of an apparatus embodying the present invention;  
     [0010]FIG. 2 is a side view of the apparatus of FIG. 1 partially broken away.  
     [0011]FIG. 3 is a side view of a portion of the apparatus better illustrating a coupling between the engine and the compressor;  
     [0012]FIG. 4 is a top view of the portion of the apparatus shown in FIG. 3;  
     [0013]FIG. 5 is a side view of an alternate construction of an apparatus embodying the present invention partially broken away;  
     [0014]FIG. 6 is an exploded view of the apparatus of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0015] As shown in FIG. 1, an engine driven air compressor unit  10  includes a cart  15 , an air compressor  20 , an engine  25 , a pair of accumulator tanks  30 , and various gauges  35 , controls  40 , and point-of-use connections  45 . The cart  15  includes a frame  50  that structurally supports the various components of the compressor unit  10  and defines a central plane A-A. The central plane A-A divides the cart  15  into a front mounting portion  55  and a rear mounting portion  60 . The cart  15  also includes a handle portion  65  and a plurality of wheels  70  that allow the cart  15  and the air compressor unit  10  to be mobile. Generally, the cart frame  50  is fabricated from tubular steel or aluminum with any structural material being a suitable substitute so long as it can support the weight of the components. The tubular members connect to one another using any common attachment method with welding being preferred. Other attachment methods include, but are not limited to, bolting, brazing, and soldering. Round or square cross-sectional tubes may be used to fabricate the cart  15 , however, other shapes will also function. The frame  50  extends above the engine  25  and air compressor  20  to define the handle portion  65  of the cart  15 . The user is able to move the cart  15  onto its wheels  70 , and maneuver the cart  15  using the handle portion  65  of the frame  50 . In other constructions, separate handle members may extend from the frame  50  to facilitate movement of the cart  15 .  
     [0016] The cart  15  includes two wheels  70 , each rotatably attached to an axle. The axle may be a single axle connected to both wheels  70 , or may be two distinct axles disposed on a common axis. To move the compressor unit  10 , a user applies a force to the handle portion  65  of the frame  50  to pivot the compressor unit  10  onto the wheels  70 . The compressor unit  10  is then movable to any desired location. In other constructions, three or more wheels  70  may allow the compressor unit  10  to be moved without having to tip it onto the two wheels  70 . Two parallel axles spaced apart from one another support at least three wheels  70  with the compressor unit  10  completely supported by the wheels  70 . In still other constructions, a plurality of pivotable castors support the cart  15  for movement as desired.  
     [0017] The air compressor  20  is supported within a housing  75  that attaches to the cart  15 . The air compressor housing  75  substantially encloses the air compressor  20  as well as the piping needed to contain and direct the compressed air. The pipes interconnect a high-pressure air outlet  80  of the compressor  20  (shown in FIGS. 3 and 5) and the inlet of the accumulator  30 . In addition, many constructions include a pressure switch or a pressure relief valve (not shown) that allows the user to select the desired storage pressure of the high-pressure air within the accumulator  30 . Pipes also extend from the accumulator  30  to various point-of-use connections  45  where the air is discharged and used. In addition, various tubes and pipes may extend from the accumulator  30  or the compressor  20  to instrumentation or controls to provide the user with information and allow for the control of the compressor unit  10 . For example, a tube may extend from the accumulator  30  to a pressure gauge  35 , thereby allowing the user to visually check the pressure within the accumulator  30 . A large portion of these tubes and pipes are substantially contained within the housing  75 . Because the location and use of tubes and pipes to convey air are well known, the pipes and tubes have been omitted from the figures to improve clarity.  
     [0018] In addition to containing and protecting the various pipes and tubes, the housing  75  also functions as a base to support the engine  25 . A bolt pattern  85  (best shown in FIG. 6) drilled or otherwise formed into the housing  75  allows for direct connection of the engine  25  to the housing  75 . By using a standard bolt pattern  85  (e.g., ANSI, SAE, or ISO standard flange patterns), many different engines  25  can easily attach to the housing  75  and drive the compressor  20 . Alternatively, the housing includes a bolt pattern as described in U.S. Pat. No. 5,546,901, assigned to Briggs &amp; Stratton Corporation and herein fully incorporated by reference. Bolts  90  extend through an engine flange  95  and thread into the housing  75  or pass through the housing  75  and engage a nut. In another construction, the bolts  90  pass through the housing  75  and thread into the engine flange  95  or pass through the engine flange  95  and engage nuts.  
     [0019]FIG. 2 is a partially broken away section view of one possible air compressor  20 . The compressor  20  includes a piston  100  positioned to reciprocate within a cylinder  105  and coupled to a drive member such as a crankshaft  110 . The crankshaft  110  or another shaft coupled to the crankshaft  110  extends vertically along a vertical axis  7 - 7 . A coupling member  115  (discussed below) attaches to the end of the crankshaft  110 , or is formed as part of the crankshaft  110 , to facilitate connection of the air compressor  20  to the engine  25 . Rotation of the crankshaft  110  about the vertical axis  7 - 7  produces a reciprocating motion of the piston  100 , which in turn produces a flow of high-pressure air. While a piston-type air compressor  20  is illustrated in FIGS.  2 - 5 , many other types of air compressors (e.g., gear-type, screw-type, centrifugal-type, and axial-type compressors) may function with the invention. The actual type of air compressor employed is of little importance to the invention so long as the air compressor can be driven through a vertically extending shaft.  
     [0020] The coupling member  115  of FIG. 2 is formed as part of the crankshaft  110  and extends vertically toward the top of the housing  75 . The crankshaft  110  includes an opening sized to receive the engine drive shaft  120 . In some embodiments, the engine drive shaft  120  and coupling member  115  are splined, thereby allowing them engage one another and transmit rotational movement, while still allowing for relative vertical movement. In a preferred embodiment, the engine drive shaft  120  and the coupling member  115  are threaded. Rotation of the engine drive shaft  120  threads the drive shaft  120  into the coupling member  115 .  
     [0021] FIGS.  3 - 5  illustrate another construction of the air compressor employing a drive member including a separate offset-plate drive  125  rather than a crankshaft  110  and integral coupling member  115 . The offset-plate drive  125  includes a collar portion  130  and a plate portion  135 . The collar portion  130  can attach to the plate portion  135  or they can be manufactured as one contiguous piece. The collar portion  130  attaches to the engine drive shaft  120  such that rotation of the engine shaft  120  rotates the offset-plate drive  125  about the vertical axis  7 - 7 . The collar portion  130  of FIG. 3 is generally a short hollow tube having an internal bore threaded to receive the drive shaft  120  that extends from the engine  25 . The drive shaft  120  threads into the internal bore of the collar portion  130  to couple the compressor and the engine. In other constructions (not shown), the collar portion  130  is part of the engine drive shaft  120 , while the offset-plate drive  125  includes a threaded bar portion extending vertically along axis  7 - 7  and sized to fit within the collar.  
     [0022] The plate portion  135  includes a connection point  145  that is spaced a distance from the vertical axis  7 - 7 . A connecting rod  150  connects at a first end to the piston  100  and at a second end to the connection point  145  on the plate portion  135 . Rotation of the plate  135  results in the connection point  145  and the second end of the connecting rod  150  moving in a circular path around the vertical axis  7 - 7 . This orbital motion produces the desired reciprocating motion at the piston  100 . In another construction (not shown), the plate  135  is a bar having a first end and a second end. The collar  130  attaches to the first end of the bar, while the connection point  145  is disposed near the second end of the bar. Engine operation rotates the second end of the bar about the first end, thereby producing the desired reciprocating motion of the piston  100 . The actual shape of the plate  135  is not critical to the invention, so long as it provides a connection point  145  to connect the connecting rod  150  so that it is offset from the vertical axis  7 - 7 .  
     [0023] The connecting rod  150  pivotally connects to the connection point  145  to allow relative movement between the connecting rod  150  and the plate  135 . FIG. 4 illustrates one possible way of facilitating relative movement between the connecting rod  150  and the plate  135 , wherein the connecting rod  150  includes a bearing  155  that allows for its free rotation about a pin  160 . The pin  160  can be a pin, or a bolt threaded into the plate  135  and sized to receive the bearing  155 .  
     [0024] Many internal combustion engines can be adapted to drive a compressor  20 . For example, a common lawnmower engine includes a shaft extending vertically and can be connected to the housing  75  to drive the air compressor  20 . The engine  25 , as shown in FIG. 5, includes an engine housing  163  and the engine flange  95  that attaches to the compressor housing  75  and supports the engine  25 , although other mounting arrangements may be used. The engine housing  163  at least partially encloses the moving parts of the engine. In addition, the engine housing  163  provides an opening through which the engine drive shaft  120  extends. The engine  25  includes the drive shaft  120  that extends vertically out of the engine  25 . The flange  95  includes a bolt pattern  157  that matches the pattern  85  in the housing  75 .  
     [0025] The invention has been described and illustrated with the air compressor  20  disposed below the internal combustion engine  25 . Alternatively, the engine  25  could be positioned below the air compressor  20 . In this alternative arrangement, the engine drive shaft  120  extends vertically up to engage the air compressor  20 .  
     [0026] The construction illustrated in FIGS. 1 and 6 includes two accumulator tanks  30  supported by the cart  15  and disposed in the rear mounting portion  60 . Tanks  30  are positioned on the opposite side of plane A-A from engine  25 , as shown in FIG. 1. Positioning the tanks  30  in the rear mounting portion  60  allows the weight of the tanks  30  to partially offset the weight of the air compressor  20  and the internal combustion engine  25 . By partially balancing the weight on either side of the rear wheels  70 , the cart  15  becomes easier to pivot onto the wheels  70  when movement is desired.  
     [0027] The accumulator tanks  30  receive the flow of compressed air from the air compressor  20  and provide a flow of compressed air to the point-of-use connections  45  for use. Accumulator tanks  30  allow for the storage of compressed air, thereby reducing pressure variations of the air at the point-of-use. In addition, the use of accumulators  30  allows the compressor  20  to cycle less frequently, thereby reducing starts and stops and improving component life.  
     [0028]FIGS. 1 and 2 illustrate two elongated tanks  30  oriented with their longitudinal axis being substantially parallel to axis  7 - 7 . In other constructions, a single larger tank is employed. The actual configuration of the tank is unimportant to the function of the invention. The quantity and orientation of the tanks can very greatly, however, the internal volume of the tanks and the tank construction should be sufficient to contain the desired volume of air at the desired air pressure.  
     [0029] In operation, the engine rotates the drive shaft  120 , which in turn rotates the coupling  125  about the vertical axis  7 - 7 , thereby producing the desired reciprocating motion of the piston  100 . As the piston  100  retracts within the cylinder  105 , a partial vacuum is produced. The vacuum allows an inlet reed valve  165  to open and admit air. As engine rotation continues, the piston  100  reverses and moves towards the closed end of the cylinder  105 . The enclosed volume within the cylinder  105  decreases and the air pressure increases, thereby forcing an outlet reed valve  170  open and the inlet reed valve  165  closed. The high-pressure air flows out a pipe (not shown) to the point-of-use connections  45  and to the accumulator  30 . When the air pressure reaches the desired pressure, the engine  25  shuts off, or alternatively a relief valve (not shown) opens allowing the engine  25  to idle without compressing air. While simple reed valves  165 ,  170  have been described, one-way check valves, solenoid-operated valves, or pressure control valves could also be used to control the flow of air into and out of the compressor cylinder  105 . In addition, the invention has been described in terms of a single cylinder  105  acting as a compressor  20 . However, the invention should not be limited to single-cylinder compressors, as it will function equally well with multi-cylinder compressors.  
     [0030] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.