Abstract:
A valve for a tire with a simple structure and a low cost is easily made for monitoring the pressure of the tire through an indicator.

Description:
FIELD OF THE INVENTION  
   The present invention relates to a valve; more particularly, relates to monitoring a tire pressure at any time with an easily fabricated and assembled tire valve having a reduced cost. 
   DESCRIPTION OF THE RELATED ARTS  
   As disclosed in U.S. Pat. No. 5,103,670, “Tire valve and pressure gauge”, a first prior art comprises a housing being engaged within a tire valve stem; a bellows being engaged within the housing and functioning to produce movement of a portion upon exposure, where the bellows is in pneumatic communication with the air pressure within the tire and is cylindrical in shape and formed for compressible movement along the central axis, and Where a calibrated spring is disposed within the bellows and is operable to balance the movement of the bellows caused by the changing tire pressure; and a driving rod being formed with a first end and a second end, where the first end of the driving rod is engaged to the bellows and the second end of the driving rod has a rotational engagement means and the driving rod is slidably engaged within the housing, such that movement of the bellows results in axial movement of the driving rod along the linear central axis. The combination of the first prior art is formed to be substantially the same size as a general tire valve stem, such that it may be used as a replacement part. A window is formed in the tire stem to permit viewing of the pressure indicator, whereby different numerals corresponding to different tire pressures become visible in the window upon rotation of the indicator which is caused by movement of the bellows. An air channel is formed through the device to permit air to be pumped into the tire. A rotary indicator having an internal spiral groove rotates upon a driving rod formed with projecting driving pin members that project into the spiral groove to cause the rotation of the indicator. 
   A second prior art is disclosed in U.S. Pat. No. 5,103,670, “Tire valve and pressure gauge”, comprising a bracket structure mounted to a rim of a wheel assembly and extending inwardly from the rim of the wheel assembly toward a hub of the wheel assembly such that the bracket structure does not protrude from the wheel assembly; at least one air pressure gauge mounted to the bracket structure distal from the rim of the wheel assembly such that the at least one air pressure gauge does not protrude from the wheel assembly; and a pneumatic conduit being in communication with the at least one air pressure gauge and a valve stem of a pneumatic tire. The second prior art includes a pair of the analog/digital readout pressure gauges and associated valve stems for individually monitoring and pressurizing the tire or tires of the wheel assembly. The tire pressure indication system may be attached to the outside wheel of a dual wheel assembly by the bracket structure with an adhesive tape or other suitable fastener. The tire pressure indication system provides can be easily mounted to the wheel tire assembly without the use of a hubcap or other similar mounting structure. 
   The above two prior arts can be used for monitoring the tire pressure of a tire; yer, the costs are high, the structures are complicated, and they are not used with ease. There are still some other prior arts having one or some of the following shortages: complicated fabrication, bad measurement precision, complex circuits, and recharge-required power supplier. Hence, the prior arts do not fulfill users&#39; requests on actual use. 
   SUMMARY OF THE INVENTION  
   The main purpose of the present invention is to depose a movable indicating device in a bushing to monitor a tire pressure at any time. 
   Another purpose of the present invention is to obtain a valve with simple structure which is easily fabricated with a reduced cost. 
   To achieve the above purposes, the present invention is a tire valve having an indicating device, comprising a bushing fixed to a tire inlet of a tire, where the bushing has an air-pumping mouth at an end and a window is deposed at a proper position of the bushing; and an indicating device movably deposed in the bushing between the tire inlet and the air-pumping mouth, where the indicating device comprises a bag filled with a required gas or having a bag inlet, a folding part connected with the bag, and an indicator deposed on the folding part, and where the indicator is corresponding to the window. Accordingly, a novel tire valve having an indicating device is obtained. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
     The present invention will be better understood from the following detailed descriptions of the preferred embodiments according to the present invention, taken in conjunction with the accompanying drawings, in which 
       FIG. 1  is a cross-sectional view showing a first preferred embodiment according to the present invention; 
       FIG. 2A  is a view showing a state of use of the first preferred embodiment according to the present invention; 
       FIG. 2B  is a cross-sectional view showing a partial enlargement of  FIG. 2A  according to the first preferred embodiment of the present invention; 
       FIG. 3  is a cross-sectional view showing a second preferred embodiment according to the present invention; 
       FIG. 4A  is a view showing a state of use of the second preferred embodiment according to the present invention; 
       FIG. 4B  is a cross-sectional view showing a partial enlargement of  FIG. 4A  according to the second preferred embodiment of the present invention; and 
       FIG. 5  is a cross-sectional view showing a third preferred embodiment according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS  
   The following descriptions of the preferred embodiments are provided to understand the features and the structures of the present invention. 
   Please refer to  FIG. 1 , which is a cross-sectional view showing a first preferred embodiment according to the present invention. As shown in the figure, the present invention is a tire valve having an indicating device, comprising a bushing  1  and an indicating device  2 , where a tire pressure is monitored with an easily fabricated and assembled tire valve having a reduced cost. 
   The bushing  1  has an air-pumping mouth  11  at an end, and a window  12  deposed at a proper position at a side; and, a required pump mark  121  is marked on the window  12 . 
   The indicating device  2  is movably deposed in the bushing  1 , comprising a bag  21  filled with a required gas; a folding part  22  connected with the bag  21 ; and an indicator  23  deposed on the folding part  22 , where the indicator  23  is corresponding to the window  12 . 
   Hence, a novel tire valve having an indicating device is obtained. 
   Please refer to  FIG. 2A  and  FIG. 2B , which are a view showing a state of use and a cross-sectional view showing a partial enlargement of  FIG. 2A , according to the first preferred embodiment of the present invention. As shown in the figures, the present invention is applied to a tire  3 , where, as shown in  FIG. 2B , which shows a partial enlargement  4  of  FIG. 2A , a bushing  1  is fixed to a tire inlet  31  of the tire  3 ; and, an indicating device  2  is movably deposed in the bushing  1  between the tire inlet  31  and an air-pumping mouth  11  at an end of the bushing  1 . 
   When a gas is pumped into the tire  3  through the air-pumping mouth  11  the gas enters from the tire inlet  31  into the tire  3  through the bushing  1  for pumping the tire  3  with the gas. When the gas pressure of the tire  3  becomes equal to that of the bag  21  of the indicating device  2 , which means the gas pressures are balanced in between, an indicator  23  of the indicating device  2  indicates at a position below a pump mark  121  on a window  12  of the indicating device  2 . When the gas in the tire  3  leaks, the gas pressure in the tire  3  becomes smaller than that in the bag  21 . Because a result of multiplying the number of the gas pressure and that of the size of the bag  21  is a constant, a folding part  22  connected with the bag  21  is raised by the change in the size of the bag  21  caused by the change in the size of the tire  3 ; and, so, the indicator  23  of the indicating device  2  deposed on the folding part  22  indicates at a position above the pump mark  121  to warn a driver over an insufficient tire pressure. 
   Please refer to  FIG. 3 , which is a cross-sectional view showing a second preferred embodiment according to the present invention. As shown in the figure, the indicating device  2   a  is movably deposed in the bushing  1 , comprising a bag  21   a  having a bag inlet  211   a;  a folding part  22   a  connected with the bag  21   a;  and an indicator  23   a  deposed on the folding part  22   a,  where the indicator  23  is corresponding to the window  12  and the bag inlet  211   a  has a membrane  212   a.    
   Please refer to  FIG. 4A  and  FIG. 4B , which are a view showing a state of use and a cross-sectional view showing a partial enlargement of  FIG. 4A , according to the second preferred embodiment of the present invention. As shown in the figures, the present invention is applied to a tire  3 , where, as shown in  FIG. 4B , which shows a partial enlargement  4  of  FIG. 4A , a bushing  1  is fixed to a tire inlet  31  of the tire  3 ; and, an indicating device  2   a  is movably deposed in the bushing  1  between the tire inlet  31  and an air-pumping mouth  11  at an end of the bushing  1 . 
   When a gas is pumped into the tire  3  through the air-pumping mouth  11 , the gas enters from the tire inlet  31  into the tire  3  through the bushing  1  for pumping the tire  3  with the gas. Meanwhile, a part of the gas enters into the bag  21   a.  When the gas pressure of the tire  3  becomes equal to that of the bag  21   a  of the indicating device  2   a  and the gas is prevented from leaking out of the bag  21   a  by closing the membrane  212   a,  which means the gas pressures are balanced between the bag  21   a  and the tire  3 , an indicator  23   a  of the indicating device  2   a  indicates at a position below a pump mark  121  on a window  12  of the indicating device  2   a.  When the gas in the tire  3  leaks, the gas pressure in the tire  3  becomes smaller than that in the bag  21   a  and a folding part  22   a  connected with the bag  21   a  is raised by the change in the size of the bag  21   a  caused by the change in the size of the tire  3 . As a result, the indicator  23   a  of the indicating device  2   a  indicates at a position above the pump mark  121  on the window  12  to warn a driver over an insufficient tire pressure. 
   Please refer to  FIG. 5 , which is a cross-sectional view showing a third preferred embodiment according to the present invention. As shown in the figure, a leakage-preventing device  5  is deposed beyond a bag  21   b  in a bushing  1 . The leakage-preventing device  5  comprises a valve stem  51 ; a valve seat  52  connected with the bag  21   b  with a spring; and a valve ball  521  in the valve seat  52  connected with the bag  21   b  with the stem  51 . When a leakage happens to a window  12  of the bushing  1  and so a gas pressure outside of the bag  21   b  is reduced rapidly, the valve seat  52  is shut by the valve ball  521  to prevent the gas from leaking out. On the contrary, under a normal situation, the valve ball  521  is pushed down to open the valve seat  52  for communicating the gas. 
   To sum up, the present invention is a tire valve having an indicating device, where a tire pressure can be monitored at any time with an easily fabricated and assembled tire valve having a reduced cost. 
   The preferred embodiments herein disclosed are not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.