Abstract:
A compressor system is disclosed utilizing a first pump driven by an A/C motor and a second pump driven by a D/C motor. A gauge is provided which measures pressure from the system. The gauge utilizes a rotatable bezel which allows an operator to selectively choose the output pressure of the compressor system. The gauge provides a shut-off mechanism for disengaging one of the pumps when a predetermined pressure is reached within the system.

Description:
FIELD 
       [0001]    The present disclosure relates to an air compressor and, more particularly, to an air compressor with a user settable automatic shut-off feature. 
       BACKGROUND 
       [0002]    The statements in this section are merely background information and may not constitute prior art. 
         [0003]    One of the main features of portable compressors is their ability to be used in diverse environments. Unfortunately, the availability of standard A/C or D/C power in these environments may be limited. To overcome this, compressors are typically driven by a D/C motor with associated circuitry which provides D/C power either from an A/C or a D/C input. The circuitry associated with input detection and conversion is often energy inefficient and expensive. 
         [0004]    Another feature which is desirable is to control the output pressure on the compressor. Typically, systems have in-line gauges which are used to allow a user to monitor the output pressure of the compressor. Inattention on the part of the operator or a failure of a shut-off mechanism, however, may lead to over pressurization of the system. 
       SUMMARY 
       [0005]    It is an object of the present invention to overcome the aforementioned disadvantages of the prior art. As such, disclosed herein is a portable compressor having a first compressor coupled to a D/C motor and a second compressor coupled to an A/C motor. The outputs of the first and second compressors are fluidly coupled to a gauge and an output hose. 
         [0006]    In one embodiment, the system as described above has a gauge with a user settable shut-off mechanism that cuts power to both of the motors when the system pressure reaches a user settable level. In another embodiment, a compressor is disclosed having a gauge with a rotatable bezel having a needle stop. The shut-off mechanism is engaged when the needle interacts with the needle stop. 
         [0007]    In yet another embodiment, a compressor system is provided which utilizes a gauge having a shut-off mechanism. The shut-off mechanism has a movable member which allows the user to set a cut-off system pressure. The gauge has a first needle rotatably coupled to a rotatable gauge shaft. A second needle is fixably coupled to the rotatable shaft. A spring is disposed between the first and second needles to bias the first needle into contact with the second needle, so that rotation of the gauge shaft in response to changes in pressure in the system causes rotation of both the first and second needles. A signal is provided to stop the compressor when the first needle interacts with or encounters the movable member. The first needle indicates pressure in the system irrespective of the location of the movable member, or the first needle. 
         [0008]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0009]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0010]      FIG. 1  represents a compressor according to the teachings of the present invention; 
           [0011]      FIG. 2  represents a top cross-sectional view of the compressor shown in  FIG. 1 ; 
           [0012]      FIG. 3  represents a cross-sectional end view of the compressor shown in  FIG. 1 ; 
           [0013]      FIGS. 4 and 5  represent the use of the gauge shown in  FIG. 3 ; 
           [0014]      FIG. 6  represents a cross-sectional view of an alternate gauge; and 
           [0015]      FIG. 7  represents the alternate gauge shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0017]      FIG. 1  represents a cross-sectional view of a compressor  10  according to the teachings herein. Disposed within an exterior housing  12  are first and second pumps  14  and  16 . The piston driven air pumps  14  and  16  function to compress ambient air and provide it to an output hose  22 . In this regard, the pump output ports  18  and  20  are fluidly coupled to the output hose  22  through a “Y” coupling adapter  24 . Optionally, an accumulator or tank (not shown) can be disposed between the pumps  14  and  16  and the output hose  22 . 
         [0018]    The first pump  14  is driven by a D/C motor  28 , while the second pump  16  is powered by an A/C motor  30 . As best seen in  FIG. 2 , the housing  12  has a pair of electrical supplies in the form of connectors  32  and  34 . The first connector is configured to accept D/C power which is coupled to the first motor  28 . It is envisioned that the D/C supply would provide power at between 3 and 24 volts. The second connector  34  is configured to provide A/C power to the second motor  30 . The voltage of the A/C supply can be adjusted to accommodate international supply requirements. It is additionally envisioned the compressor can contain batteries and/or a transformer. 
         [0019]    Disposed between the first and second connectors  32  and  34  is a three position switch  36 . In a first position, the switch  36  functions to allow current flow from the first connector  32  to the first motor  28 . The third position allows currents to flow from the second connector  34  to the second motor. The middle position is an off position that prevents current from flowing to either of the pump motors. In this particular configuration, only a single motor can be energized at a given time, even if both connectors  32  and  34  are coupled to power simultaneously. 
         [0020]    As shown in  FIG. 4 , the system additionally has a pressure gauge  38  which functions to measure system pressure achieved by either of the first or second pumps  14  and  16 . The gauge  38 , while measuring the air pressure within the system, also functions as a user settable shut-off mechanism. The gauge  38  has a user movable member in the form of a rotatable bezel  40 . Disposed on an interior surface  42  of the bezel  40  is a stop  44 . The stop  44  has an indicator  46  which the user can position at a desired cut-off pressure level  44 ′. 
         [0021]    The gauge  38  allows the user to set a desired pressure in the system by cutting off power to one or both of the pumps once the gauge needle  48  engages the stop  44 . Generally, the signal provided from the shut-off mechanism can be generated several ways. The needle  48  is coupled to a rotatable shaft  52  which rotates in response to changes in pressures in the system. In this regard, it is envisioned the engagement of the needle  48  with the stop  44  can function either as an open or closed switch. Additionally, it is envisioned that the bezel  40  can have a magnetorestrictive sensor which would sense movement of a magnetic member (not shown) disposed on the needle  48 . 
         [0022]    The shut-off mechanism is configured to provide a signal which will be used by the system to interrupt power to one or both of the motors  28  and  30 . As shown in  FIGS. 4-6 , rotation of the bezel adjusts the location of the stop  44  and, hence, the shut-off pressure. The needle  48  and stop  44  are electrically coupled to a power circuit so that when a needle  48  hits the stop  44 , the circuit is closed and power to the pump motors is interrupted. Optionally, the needle  48  can form a short circuit across the power supply, driving the first and second motors  28  and  30 . Additionally, the short can function to actuate a relay or transistor to cut-off power to the motors  28  or  30 . 
         [0023]    Optionally, the gauge  38  can be formed of a pair of needles  48  and  54  which are coupled to the shaft  52 . The first needle  48  can be rotatably coupled to the shaft  52 , while the second needle  54  can be fixably coupled to the shaft  52 . Disposed between the first and second needles  48  and  54  is a spring  53  that rotatably biases the first needle  48  toward and into the second needle  54 . Either one of the needles can have a flange  55  which allows the simultaneous rotation of the first  48  and second needles  54 . 
         [0024]    The first needle  48  is attached to the shaft  52  of the gauge by means of a bearing system so that it can float on the shaft  52 . Travel of the first needle  48  is limited by the bottom range of the gauge  38  and the position of the stop  44  of the bezel  40 . As described above, the first needle  48  can make electrical contact with the bezel&#39;s fixed stop contact  44  and can function to switch off the power to the pump motor. The first needle  48  is connected to the second needle  52  by means of the coil spring  53  in a manner that will hold it in position directly above the second needle  52 . Travel of the second needle  52  is not limited by the bezel stop or contact  44 . 
         [0025]    As seen in  FIGS. 6 and 7 , the first needle  48  can have a length so as to allow interaction with the stop  44 , while the second needle  52 , which can be positioned below the first needle  48 , is configured so as to allow it to move past the stop  44  to indicate the measured pressure in the system. If the compressor system should fail, and the pressure in the system goes above the bezel contact set location, the first needle  48  will stop at the bezel contact  44 . In this position, the first needle  48  will float on the shaft  50  of the gauge  38 . The second needle  52  will continue to move, showing that the pressure in the system is rising above the desired cut-off pressure. This condition will alert the user that the pump has not stopped or another failure condition has occurred, causing a higher than desired pressure in the system. 
         [0026]    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.