Abstract:
A mobile tire inflator includes a control panel, multiple air passages, an inflation valve, a discharge valve and a pressure sensor. The user can control the operation of the inflation valve and the discharge valve automatically or manually by means of the control panel, switch between the automatic mode and the manual mode during operation. Matching with the operation of the pressure sensor, the mobile tire inflator achieves accurate tire pressure inflation and discharge and has the advantages of operation flexibility and high mobility.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to tire inflators and more particularly, to a mobile tire inflator. 
         [0003]    2. Description of the Related Art 
         [0004]    Conventionally, a tire inflator must be continuously pushed and pulled to inflate a tire to a saturated condition. This operation is inconvenient. Further, when inflating the tire, the tire pressure value is displayed at the end of air pressure source (for example, the pressure gauge of the air compressor). Thus, the user cannot know the current tire pressure of the tire and the tire may be over-inflated or under-inflated. 
         [0005]    In view of the aforesaid drawbacks, a fixed type of automatic tire inflator was created. During the use of this fixed type of automatic tire inflator, attach the air tube of the fixed type of automatic tire inflator to the air valve of the tire and then operate the face panel of the fixed type of automatic tire inflator to input a target tire pressure. At this time, the fixed type of automatic tire inflator automatically inflates the tire till that the tire pressure of the tire reaches the set target tire pressure value, This design of fixed type of automatic tire inflator avoids over-inflation or under-inflation. 
         [0006]    However, the aforesaid fixed type of automatic tire inflator is huge and heavy, and cannot be carried by the user. It can only be set in a fixed place (for example, gas station) for regular use, not practical to fit different needs. Further, the aforesaid fixed type of automatic tire inflator simply provides an automatic inflation mode, giving no flexibility in use. Further, tire pressure display and add/deduct functions are designed at the face panel of the fixed type of automatic tire inflator that is disposed far away from the user, making the operation inconvenient. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a mobile tire inflator, which has the advantages of operation flexibility, high mobility and ease of use. 
         [0008]    To achieve this and other objects of the present invention, a mobile tire inflator comprises a housing, which comprises an air intake passage, an air outlet passage, an air discharge passage and a main air passage in communication with the air intake passage, the air outlet passage and the air discharge passage, the air intake passage being adapted for connecting to an external air pressure source, the air outlet passage being connectable to an air valve of the tire to be inflated/discharged, the air discharge passage being in communication between the main air passage and the atmosphere; a control panel, which is mounted in the housing and comprises a processing unit, a control unit and a display unit respectively electrically connected to one another, the processing unit comprising a switching circuit, the control unit comprising a mode-switching button and a setting button set, the mode-switching button being operable to switch the switching circuit between a manual mode and an automatic mode, the setting button set being operable to set a target tire pressure value after start of the automatic mode, the setting button set being operable to increase/decrease the current tire pressure of the tire after startup of the manual mode, the display unit being adapted to display the target tire pressure value and the current tire pressure value of the tire; an inflation valve, which is electrically connected to the processing unit and set between the air intake passage and the main air passage to control connection between the air intake passage and the main air passage; a discharge valve, which is electrically connected to the processing unit and set between the air discharge passage and the main air passage to control connection between the air discharge passage and the main air passage; and a pressure sensor, which is installed in the main air passage and electrically connected to the processing unit for measuring the current tire pressure value of the tire to be inflated. When the automatic mode is started up and the pressure sensor senses the tire pressure of the tire to be greater than a predetermined threshold value, the inflation valve/the discharge valve is automatically opened for enabling a compressed air of the air pressure source to go into/out of the tire, and automatically closed when the current tire pressure of the tire reaches the set target tire pressure value. The mode-switching button is operable to switch from the automatic mode to the manual mode during running of the automatic mode, for enabling the inflation valve/the discharge valve to be opened after the setting button set having been operated. The inflation valve/the discharge valve is openable to increase/decrease the current tire pressure of the tire after the setting button set is operated and after startup of the manual mode. The mode-switching button is operable to switch from the manual mode to the automatic mode during running of the manual mode, for enabling the inflation valve/the discharge valve to be opened automatically. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic sectional view of a mobile tire inflator in accordance with the present invention, illustrating the arrangement of the control panel. 
           [0010]      FIG. 2  illustrates the internal structure and arrangement of air passages of the mobile tire inflator shown in  FIG. 1 . 
           [0011]      FIG. 3  is a function block diagram of the mobile tire inflator in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Referring to  FIGS. 1-3 , a mobile tire inflator  100  in accordance with the present invention is shown comprising a housing  10 , a control panel  20 , an inflation valve  30 , a discharge valve  40 , a pressure sensor  50 , a check valve  60 , a power supply unit  70  and a speaker  80 . 
         [0013]    The housing  10  includes a handle  11  and a head  12 . The handle  11  is configured for grasping thereof by a person&#39;s hand. The head  12  has an air intake pipe  13  located on the periphery for the connection of an external air pressure source (not shown; for example, air compressor), an air outlet pipe  14  located on the periphery for connecting to a tire&#39;s air valve (not shown), an air intake passage  15  and an air outlet passage  16  defined therein and respectively connected to the air intake pipe  13  and the air outlet pipe  14 , an air discharge passage  17 , and a main air passage  18  in communication with the air intake passage  15 , the air outlet passage  16  and the air discharge passage  17 . The air discharge passage  17  extends from the main air passage  18  to the outside of the housing  10 . The main air passage  18  includes a horizontal segment  181  and a vertical segment  182  perpendicularly extending from one end of the horizontal segment  181 . 
         [0014]    The control panel  20  is a circuit board mounted in the head  12  of the housing  10 , comprising a processing unit  21 , a control unit  22  and a display unit  27  that are electrically connected to one another. The processing unit  21  has a built-in switching circuit and a threshold value (for example, 3 PSI). The control unit  22  comprises a mode-switching button  23 , a setting button set including an Add (+) button  24  and a Deduct (−) button  25 , and a Start button  26 . Clicks the mode-switching button  23  will cause switching of the switching circuit between a manual mode and an automatic mode. When under the automatic mode, the user can press the Add (+) button  24  or the Deduct (−) button  25  to set a target tire pressure value. When under the manual mode, the user can press the Add (+) button  24  or the Deduct (−) button  25  to increase or reduce the current tire pressure. Detailed description will be explained latter. Further, the target tire pressure value and the current tire pressure value can be displayed on the display unit  27  for viewing by the user. 
         [0015]    It is to be understood that the mode-switching button  23  is also used a tire pressure unit conversion button to convert tire pressure units (including the units of PSI, Bar, KPa and Kgf/cm 2 ); the Deduct (−) button  25  is also used for starting up the mobile tire inflator  100 ; the Start button  26  is also used as reset button to zero the target tire pressure value. Thus, the size of the mobile tire inflator  100  can be greatly reduced. 
         [0016]    The inflation valve  30  is an electromagnetic valve electrically connected to the processing unit  21  and set between the air intake passage  15  and the main air passage  18  to control connection between the air intake passage  15  and the main air passage  18 . As this electromagnetic valve is of the known art, no further detailed description in this regard is necessary. 
         [0017]    The discharge valve  40  is an electromagnetic valve electrically connected to the processing unit  21  and set between the air discharge passage  17  and the main air passage  18  to control connection between the air discharge passage  17  and the main air passage  18 . 
         [0018]    The pressure sensor  50  is installed in the vertical segment  182  of the main air passage  18 , and electrically connected to the processing unit  21  for measuring the current tire pressure value of the tire. 
         [0019]    The check valve  60  is installed in the air intake passage  15 , and functioning to let the mobile tire inflator  100  be used as a tire pressure gauge when the mobile tire inflator  100  is not connected to the external air pressure source. 
         [0020]    The power supply unit  70  is electrically connected to the processing unit  21 . According to the present preferred embodiment, the power supply unit  70  comprises a lithium-ion battery  71  mounted in the head  12  of the housing  10 , and a charging terminal  72  electrically connectable to an external power source  73  to charge the lithium-ion battery  71 . 
         [0021]    The speaker  80  is electrically connected to the processing unit  21 . 
         [0022]    When using the mobile tire inflator  100 , the user can select the automatic mode or the manual mode depending on circumstances, and can switch between the automatic mode and the manual mode during operation. If the automatic mode is selected, set the target tire pressure value at first, and then connect the chuck (not shown) of the air intake pipe  13  to the air valve of the tire to be inflated. At this time, the pressure sensor  50  senses the pressure of the tire. When the pressure of the tire surpasses a threshold (for example, 3 PSI) and is below the target tire pressure value, the speaker  80  is driven to output sound, and the inflation valve  30  is opened for enabling compressed air to be charged from the external air pressure source into the tire till that the tire pressure of the tire reaches the target tire pressure value. When the tire pressure of the tire reaches the target tire pressure value, the speaker  80  is driven to output sound again, informing the user to remove the chuck from the air valve of the tire. Thus, the inflation procedure is completed. The procedure of discharging the tire pressure of the tire is operated in the same manner with the exception that the discharge valve  40  is opened for enabling tire air to be discharged out of the tire till that the tire pressure of the tire reaches the target tire pressure value. The setting of the threshold value eliminates a false action of the inflation valve  30  or the discharge valve  40  due to a pressure difference upon startup of the mobile tire inflator  100 . 
         [0023]    Further, the user can select the manual mode, and press the Add (+) button  24  and the Deduct (−) button  25  to open/close the inflation valve  30  and the discharge valve  40 , controlling inflation or discharge of compressed air to increase or reduce the current tire pressure on the real time. 
         [0024]    Further, during running of the aforesaid manual or automatic mode, the user can switch to the other mode at anytime when necessary. For example, if the automatic mode is selected and the pressure sensor  50  senses the pressure of the tire to be greater than 3 PSI, the inflation valve/discharge valve  40  will be automatically opened for enabling compressed air to be charged into or discharged out of the tire, and the inflation valve/discharge valve  40  will be automatically closed when the tire pressure of the tire measured by the pressure sensor  50  reaches the target tire pressure value. During the operation, the user can press the mode-switching button  23  to switch from the automatic mode to the manual mode, allowing the inflation valve  30  or the discharge valve  40  to be opened only when the setting button set is operated, facilitating micro-adjustment of the tire pressure. On the contrary, if the manual mode is originally set, the inflation valve  30 /discharge valve  40  will be opened to increase or reduce the tire pressure only when the setting button set is operated, facilitating micro-adjustment of the tire pressure. During running under the manual mode, the user can press the mode-switching button  23  to switch from the manual mode to the automatic mode, enabling the inflation valve  30  and the discharge valve  40  to be opened automatically, enhancing operation flexibility and convenience. For example, if much time is necessary to reach the target tire pressure value under the manual mode, the user can switch from the manual mode to the automatic mode during operation. 
         [0025]    As stated above, the invention has a control interface and a display interface be integrated into a small handheld device, facilitating carrying and enabling the user to change the setting or to view the current inflating or discharging operation. Therefore, the invention facilitates operation. Further, tire pressure inflation or discharge operation can be performed either automatically or manually to fit different conditions, enhancing flexibility in use. 
         [0026]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.