Patent Publication Number: US-2015075656-A1

Title: Adaptor for an air compressor and an air compressor

Description:
FIELD OF THE INVENTION 
     This invention relates, in general to an adaptor for an air compressor and relates more particularly, though not exclusively, to an air compressor system. 
     BACKGROUND OF THE INVENTION 
     Air compressors come in varying configurations, for example, screw compressors and piston compressors. Air is compressed and delivered by hoses to one or more air tools, for example, pneumatic drills, staple guns and other pneumatically driven devices. These tools contain an air motor which is powered by the pressurised air source from the air compressor. The air motor produces exhaust air which is vented to ambient air. The escape of exhaust air is noisy. The air compressor will not usually support sustained use of the air tool because of the resulting pressure drop. 
     It has been proposed in German Patent Application No. 24 10 832 to have the exhaust air from a compressed air tool recycled under pressure to the intake side of the air compressor via an auxiliary pressure vessel. The disclosure includes a large number of components including piping, valves and gauges which must be fitted to an existing air compressor. The compressed air return line from the auxiliary pressure vessel is connected to only one cylinder of a multiple piston-type air compressor. The auxiliary pressure vessel buffers the returning exhaust air. This proposal is impractical, in use, because of the bulk of an auxiliary tank and the additional components needed to operate the system. 
     In published Japanese Patent Application No. 2002-174203 an air actuator system is disclosed. This application illustrates the use of air actuators for an air press rather than air motors. The intake of the compressor creates a vacuum on the exhaust side of the air actuators rather than an air boost. The preferred embodiments show the use of multiple actuator valves and electronics to control the system. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an adaptor that can be fitted to any air compressor to allow sustained use of an air tool attached thereto. 
     A further object of the present invention is to provide an adaptor that can increase the output rating of an air compressor. 
     A still further object of the invention is to provide an adaptor that is easily fitted or integrated with an air compressor without using a lot of components or electronics. 
     With these objects in view the present invention in a preferred aspect may provide an adaptor for an air compressor, said adaptor including a manifold having an inlet adapted to be connected to the air exhaust of at least one air tool device having an air motor connected, in use, to said air compressor, and an outlet adapted to be connected, in use, to the air intake of said air compressor, an air inlet open to ambient air and a valve mechanism adapted to, in use, close said air inlet when a first predetermined pressure is reached by said air compressor. 
     Preferably said adaptor further includes a pressure relief valve which opens to exhaust compressed air at a second predetermined pressure. Preferably a plurality of said outlets are provided which are adapted to be connected to respective air intakes of a multiple cylinder air compressor. 
     The invention may also provide an air compressor with an adaptor of the type defined above attached or integrated therewith. 
     The invention also provides air compressor including a manifold having an inlet adapted to be connected to the air exhaust of at least one air tool device having an air motor connected, in use, to said air compressor, and an outlet adapted to be connected, in use, to the air intake of said air compressor, an air inlet open to ambient air and a valve mechanism adapted to, in use, close said air inlet when a first predetermined pressure, preferably of about 1 bar or 14.38 psi or higher is reached by said air compressor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings, in which: 
         FIG. 1  is a schematic view of an adaptor made in accordance with a preferred embodiment of the invention to be used with a screw compressor; 
         FIG. 2  is a perspective plan view of the adaptor shown in  FIG. 1 ; 
         FIG. 3  is a schematic view of an adaptor made in accordance with a second preferred embodiment of the invention to be used with a single cylinder compressor. 
         FIG. 4  is a perspective view of the adaptor shown in  FIG. 3 ; 
         FIG. 5  is a diagrammatic cross-sectional view showing the operation of the adaptor 
         FIG. 6  is a third embodiment of the adaptor shown in  FIG. 5  for a multi-cylinder compressor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIGS. 1 and 2  there is shown an adaptor  10  for connection to a screw compressor  11 . The brand or type of compressor is not relevant to the operation of the invention. This embodiment has been tested on a Ceccato 5 kW rotary screw compressor. Adaptor  10  is fitted to the air intake  12  of the compressor  11 . Compressor  11  has a tank  13  for holding compressed air for use by an air tool  34 . Adaptor  10  has a manifold  14  which mixes ambient air as indicated by arrows  17 , which is provided through air inlet  16 , and recycled compressed air  18  through compressed air inlet  20 . Compressed air inlet  20  has a connection nipple  24  which fits into a sleeve  26  within manifold  14 . Sleeve  26  includes a one-way valve  30  which opens apertures  31  when recycled exhaust compressed air  32  from air tool(s)  34  reaches a predetermined pressure. An adjustable pressure relief valve, or pair of adjustable relief valves  36  (as shown), are provided in manifold  14  and relieve excess air pressure through outlets  38 . Typically, the pressure relief valves  36  will operate at about 4 Bar to ensure that the compressed air  32  does not provide too much back pressure into air intake  12 .  FIG. 2  in this embodiment shows the actual construction of the manifold  14  with the adjustable relief valves  36  on the side, whereas  FIG. 1  shows the adjustable relief valves on the top of manifold  14  to more clearly illustrate the operation of the adaptor  10 . The adjustable relief valve(s)  36  can be located in either position. 
     In use, adaptor  10  is fitted to the compressor  11  as discussed. When compressor  11  commences operation, valve  30  will be closed as apertures  31  will be covered and air will be drawn through air inlet  16  as indicated by arrows  17 . The air will be taken directly into air intake  12  to be compressed and stored in tank  13 . The compressed air outlet  19  of from tank  13  is coupled to air tool(s)  34  which may have their exhausts returned to manifold  14  through connection nipple  24 . It is not necessary that all exhausts of all air tools be returned to connection nipple  24 . For example, a spray gun which does not have an air motor will not be connected but a drill would be. Pressure will build up in sleeve  26  until the pressure opens valve  30 . The pressure will be kept at about 4 Bar by pressure relief valve(s)  36 . Once valve  30  opens, air inlet  16  will be shut through valve  33  and a closed loop will be formed from the exhaust from the air tool(s)  34  to the air intake  12 . In an especially preferred embodiment the valve  33  will act to close the air inlet  16  at a pressure of about 1 bar or 14.38 psi or higher. The adaptor  10  will stop ambient air entering the compressor which is laden with air borne moisture. The compressed air will be drier which improves the life of the compressor  11  and the air tools  34  attached to it. As compressed air (indicated by arrows  35 ) enters the compressor  11 , the compressor  11  will have less work to do as the recycled compressed air has already been compressed to a pressure of 4 Bar. This recycling will increase the output of the compressor  11 . 
     This embodiment was tested against the compressor without fitting of the adaptor  10  thereto. Without the adaptor, and starting at 8.5 Bar, the compressor took 3 to 5 minutes before the pressure dropped back to 5.2 Bar using an air drill attached thereto. At that time the discharge air from the cooling system on the compressor was 32° C., with the air end at 57° C. and the tank discharge pipe at 22° C. 
     With the adaptor  10  fitted, it took 9 minutes for the pressure to drop to 5.7 Bar and the compressor sustained that pressure for 16 minutes when the test was terminated. At 5.7 Bar the air drill could still function at normal efficiency. When the test was terminated the discharge air from the cooling system on the compressor was 27° C. (compared with 32° C.) with the air end at 45° C. (compared with 57° C.) and the tank discharge pipe at 18° C. (compared with 22° C.). As the compressed exhaust air is colder than the ambient temperature, the compressor will run cooler. The compressor will run automatically and does not require air to either be manually allowed to escape, to prevent excess pressure, or to manually add air. These drops in temperature are significant as long term maintenance is reduced in view of the compressor running cooler. The air tools will be less noisy as the exhaust air is returned to the compressor rather than ambient air. Smaller compressors can thus be used which may avoid the use of 3 phase electric power compressors. 
     In  FIGS. 3 to 6 , an adaptor  50  is shown. Adaptor  50  in this embodiment is coupled to a piston type compressor  51 .  FIGS. 3 to 5  show adaptor  50  for a single cylinder compressor  51  whilst  FIG. 6  shows adaptor for a 3 cylinder compressor (not shown). Adaptor  50  in  FIG. 6  has a manifold  52  with three (3) air outlets  54 ,  56 ,  58  which are adapted to be connected to respective air intake ports (not shown) of each cylinder of the compressor. An adjustable pressure relief valve  60  is provided at the end of manifold  52  adjacent air outlet  54 . The pressure relief valve  60  operates in a similar manner to that of valve(s)  36  in  FIG. 1  and has an outlet(s)  62 . Arm  64  opening into manifold  52  includes a one-way valve  66  which allows ambient air  68  to enter air intake  70 . Exhaust air  72  enters exhaust inlet  74 . 
     The operation of this embodiment is similar to the embodiment of  FIGS. 1 and 2 . Air  68  is drawn into air intake  70  through open one-way valve  66  and enters manifold  52 . Air flows into air outlets  54 ,  56 ,  58  and is compressed by the compressor. Once operating pressure has been reached valve  66  will close and a closed loop will be formed from the exhaust of the air tool(s)  34  to manifold  52 . 
     In this embodiment, adaptor  50  has been tested with a McMillan single phase 2.2 kW compressor having three (3) cylinders. This embodiment was tested against the compressor without fitting of the adaptor  50  thereto. Without the adaptor and starting at 8.5 Bar, the compressor took 57 seconds before the pressure dropped back to 4.0 Bar using an air drill attached thereto. With the adaptor  50  fitted, it took 6.5 minutes for the pressure to drop to 5.0 Bar and the compressor sustained that pressure for 9 minutes when the test was terminated. At 5.0 Bar the air drill could still function at normal efficiency. 
     Although the embodiment shown in  FIG. 6  is for a multi-cylinder compressor, the invention can be used with a single cylinder compressor as shown in  FIGS. 3 to 5 . The same reference numerals have been used in  FIGS. 3 to 5  as those in  FIG. 6  to avoid repetition of description. As with the embodiment shown in  FIGS. 1  and  FIG. 2  actual construction of the manifold  50  with the air outlet  54  on the side is shown in  FIG. 4 , whereas  FIG. 5  shows the air outlet  54  on the top of manifold  52  to more clearly illustrate the operation of the adaptor  50 . The positions of air outlet  54 , relief valve  36 , air intake  70  and exhaust inlet  74  can be located in any suitable position. The invention will operate on any type of compressor and is not limited to its use with screw, vane or piston compressors. 
     The invention does not require electronics, pneumatics, switches, solenoids, auxiliary tanks or other paraphernalia that the prior art requires. The number of components has been drastically reduced resulting in a substantial reduction in maintenance. The simplicity of the invention virtually eliminates any breakdown from the invention. As the air is forced into the compressor, when operating, at above 1 atmosphere, there are less compressions from the compressor to fill the tank to the required pressure. Instead of only one bar of pressure (i.e. atmosphere) being able to enter the compressor cylinder, the invention can have up to four bar allowing the compressor to compress three times more air in one revolution. Although the invention is capable of delivering four times the power, working the machine at this level would put too great a stress on the air compressor motor. To minimise stress on the motor while optimising performance, the invention is typically tuned to deliver about twice the pressure of similar-sized conventional compressors. Air compressors are also notoriously noisy machines and the invention is able to reduce the noise by up to 50 percent. The invention has other benefits including improving occupational health and safety because it removes any potential hazard the exhausted air may cause for the operator of the tools. Moisture is reduced and heat within the air system thereby prolonging the life of the air tools. When air is compressed it creates a lot of heat and when suddenly exhausted as is the case when using the air tools that air is cooled significantly (by up to 35 degrees). In the invention, that cooled, exhausted air is now being recycled into the compression system to keep it cool. Moisture is reduced because the adaptor is not sucking in fresh, ambient air (which contains humidity) to fill the compressors. It is simply recycling the air. 
     The embodiments depict adaptors  10 ,  50  which can be retro-fitted to a compressor but they may also be integrated into the design of the compressor per se. The invention has the flexibility of being able to be used with existing compressors or can form the basis for an integrated new design in compressors. 
     The invention will be understood to embrace many further modifications as will be readily apparent to persons skilled in the art and which will be deemed to reside within the broad scope and ambit of the invention, there having been set forth herein only the broad nature of the invention and certain specific embodiments by way of example.