Abstract:
A tire pressure gauge with a light device. The device includes a cylindrical casing, a light penetrable scale mounted in the casing, a spring device mounted in the casing for biasing the scale in the casing, a piston movable in the casing, and a battery and lamp assembly which may be detachably fastened to one end of the scale outside the casing or provided inside the casing. The device further includes an air nozzle fixedly fastened to one end of the casing and adapted for being, engaged with the air valve of a vehicle tire to guide air from the vehicle tire into the casing to move the piston, causing the piston to force the scale out of the casing to an extent indicative of the pressure of the vehicle tire.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a tire pressure gauge and, more particularly, to a tire pressure gauge having lighting means for use in a dark place. 
     2. Description of Related Art 
     A conventional tire pressure gauge has an air nozzle adapted for fastening to the air valve of a vehicle tire. When fastened to the air valve of a vehicle tire, the stopper pin of the air nozzle is opened enabling pressurized air to pass from the vehicle tire into the casing of the tire pressure gauge to move a piston in the casing against a compression spring, thereby causing the piston to move a scale out of the casing to at as an indicator of the air pressure of the vehicle tire. The graduations of the scale cannot be clearly seen when a user measures the vehicle tire pressure in a dark place or the place where no sufficient illumination is provided. 
     Therefore, it is desirable to provide a tire pressure gauge that is accompanied with a lighting means. 
     SUMMARY OF THE INVENTION 
     It is the main object of the present invention to provide a tire pressure gauge, which has lighting means for illumination so that the user can use the tire pressure gauge to measure the tire pressure of the vehicle tires in a dark place. It is another object of the present invention to provide a tire pressure gauge having lighting means, which enables the user to detach the lighting means from the tire pressure gauge for use as hand-held lighting. 
     To achieve these and other objects of the present invention, the tire pressure gauge comprises a cylindrical casing, a light penetrable scale mounted in the casing, spring means mounted and supporting the scale in the casing, a piston moved in the casing, a battery and lamp assembly, and an air nozzle fixedly fastened to one end of the casing and adapted for fastening to the air valve of a vehicle tire to guide air pressure from the vehicle tire into the casing to move the piston, causing the piston to move the scale out of the casing to act as an indicator of the pressure of the vehicle tire. The battery and lamp assembly may be detachably fastened to one end of the scale outside the casing, or be provided inside the casing. Preferably, the battery and lamp assembly uses a light emitting diode as light source means. 
    
    
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded view of a tire pressure gauge according to a first embodiment of the present invention. 
     FIG. 2 is a sectional assembly view of the tire pressure gauge according to the first embodiment of the present invention. 
     FIG. 3 is a schematic view of the first embodiment of the present invention, showing that air is guided into the casing, and that the scale extends out of the first end hole of the casing. 
     FIG. 4 is an exploded view of a tire pressure gauge according to a second embodiment of the present invention. 
     FIG. 5 is a sectional assembly view of the tire pressure gauge according to the second embodiment of the present invention. 
     FIG. 6 is a schematic view of the second embodiment of the present invention, showing that air is guided into the casing, and that the scale extends out of the first end hole of the casing. 
     FIG. 7 is an exploded view of a tire pressure gauge according to a third embodiment of the present invention. 
     FIG. 8 is a sectional assembly view of the tire pressure gauge according to the third embodiment of the present invention. 
     FIG. 9 is an exploded view of a tire pressure gauge according to a fourth embodiment of the present invention. 
     FIG. 10 is a sectional assembly view of the tire pressure gauge according to the fourth embodiment of the present invention. 
     FIG. 11 illustrates the tire pressure gauge installed in the air valve of a vehicle tire according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, a tire pressure gauge  100  (see also FIG. 11) in accordance with a first embodiment of the present invention comprises a cylindrical casing  10 , a battery and lamp assembly  20 , a scale  30 , a compression spring  40 , a piston  50 , and an air nozzle  60 . The casing  10  has a first end hole  101 , a second end hole  102 , and a receiving chamber  103  in communication between the first end hole  101  and the second end hole  102 . The scale  30  admits light, having a first end  301 , a second end  302 , and a rod-like scale body  303  connected between the first end  301  and the second end  302 . According to this embodiment, the first end  301  is a screw rod. The compression spring  40  accommodates the scale  30  and, together with the scale  30 , are mounted in the receiving chamber  103  inside the casing  10 , having one end fastened to the first end hole  101  of the casing  10  and the other end fastened to the second end  302  of the scale  30 . The battery and lamp assembly  20  is detachably threaded onto the first end  301  of the scale  30 , having a rotary switch  201  for on/off control. When switching the rotary switch  201  to the “on” position, the battery and lamp assembly  20  is turned on to emit light through the scale  30 . The piston  50  is axially slidably mounted in the receiving chamber  103  of the casing  10  and is supported on the second end  302  of the scale  30 . The air nozzle  60  is fastened to the second end hole  102  of the casing  10 , and can be engaged with the air valve  91  of a vehicle tire  90  to guide air from the vehicle tire  90  to the inside of the tire pressure gauge  100  (see also FIG.  1 ). 
     FIGS. 2 and 3 show the action of the tire pressure gauge according to the first embodiment of the present invention. When in a stand-by position as shown in FIG. 2, the scale  30  is received inside the casing  10  and kept from sight. When rotating the rotary switch  201  to switch on the battery and lamp assembly  20 , light passes the battery and lamp assembly  20  through the scale  30 . After installation of the air nozzle  60  in the air valve  91  of the vehicle tire  90 , the air of the vehicle tire is guided through the air nozzle  60  into the casing  10  to push the piston  50  and overcome the bias of the compression spring  40 , as shown in FIG. 3, thereby causing the scale  30  to extend out of the first end hole  101  of the casing  10  to an extent indicative of the pressure of the air inside the vehicle tire. 
     FIG. 4 shows a tire pressure gauge according to a second embodiment of the present invention. According to this embodiment, the tire pressure gauge comprises a cylindrical casing  10 , a battery and lamp assembly  20 , a scale  30 , a compression spring  40 , a piston  50 , and an air nozzle  60 . The casing  10  has a first end hole  101 , a second end hole  102 , and a receiving chamber  103  in communication between the first end hole  101  and the second end hole  102 . The scale  30  admits light, having a first end  301 , a second end  302 , and a rod-like scale body  303  connected between the first end  301  and the second end  302 . The compression spring  40  accommodates the scale  30  and, together with the scale  30 , are mounted in the receiving chamber  103  inside the casing  10 . The battery and lamp assembly  20  is fastened to the second end  302  of the scale  30 , having a touch control switch  70  for on/off control. According to this embodiment, the battery and lamp assembly  20  uses an LED (light emitting diode) as light source. The piston  50  is axially slidably mounted in the receiving chamber  103  of the casing  10  and is supported on one end of the compression spring  40 . The compression spring  40  is fastened to the first end hole  101  of the casing  10 . The air nozzle  60  is fastened to the second end hole  102  of the casing  10 , and can be engaged with the air valve  91  of a vehicle tire  90  to guide air from the vehicle tire  90  to the inside of the tire pressure gauge  100  (see also FIG.  11 ). 
     FIGS. 5 and 6 show the action of the tire pressure gauge according to the second embodiment of the present invention. When in a stand-by position as shown in FIG. 5, the scale  30  is received inside the casing  10  and kept from sight. After installation of the air nozzle  60  in the air valve  91  of the vehicle tire  90 , the air of the vehicle tire is guided through the air nozzle  60  into the casing  10  to push the piston  50  and overcome the bias of the compression spring  40 , as shown in FIG. 6, thereby causing the piston  50  to switch on the touch control switch  70  of the battery and lamp assembly  20  and to move the scale  30  out of the first end hole  101  of the casing  10  to an extent indicative of the pressure of the air inside the vehicle tire. After measurement, the tire pressure gauge is disconnected from the air valve  91  of the vehicle tire  90 . After removal of the tire pressure gauge from the air valve  91  of the vehicle tire  90 , the scale  30  is pushed back to the inside of the casing  10 , and the touch control switch  70  is triggered by the piston  50  to switch off the battery and lamp assembly  20 . 
     FIGS. 7 and 8 show a tire pressure gauge in accordance with a third embodiment of the present invention. According to this embodiment, the tire pressure gauge is comprised of a casing  10 , a battery and lamp assembly  20 , a scale  30 , two steel balls  31 , a small spring  31 , a tensile spring  41 , a piston  50 , and an air nozzle  60 . The casing  10  has a first end hole  101 , a second end hole  102 , and a receiving chamber  103  in communication between the first end hole  101  and the second end hole  102 . The scale  30  admits light, having a first end  301 , a second end  302 , and a rod-like scale body  303  connected between the first end  301  and the second end  302 . According to this embodiment, the first end  301  is a screw rod. The battery and lamp assembly  20  is detachably threaded onto the first end  301  of the scale  30 , having a rotary switch  201  for on/off control. When switching the rotary switch  201  to the “on” position, the battery and lamp assembly  20  is turned on to emit light through the scale  30 . The steel balls  31  are respectively supported on the ends of the small spring  311  at the second end  302  of the scale  30  and disposed in contact with the inside wall of the casing  10  to effect a stable movement of the scale  30  in the casing  10 . The piston  50  is axially slidably mounted in the receiving chamber  103  of the casing  10  and stopped at the second end  302  of the scale  30  (according to this embodiment, the small spring  311  is installed in an end cap fastened to the second end  302  of the scale  30 ). The tensile spring  41  is connected between the rear of the piston  50  and a part inside the air nozzle  60 . The air nozzle  60  is fastened to the second end hole  102  of the casing  10 , and can be installed in the air valve  91  of a vehicle tire  90  to guide air from the vehicle tire  90  to the tire pressure gauge  100  (see also FIG.  11 ). When rotating the rotary switch  201  to switch on the battery and lamp assembly  20 , light passes the battery and lamp assembly  20  through the scale  30 . After installation of the air nozzle  60  in the air valve  91  of the vehicle tire  90 , the air of the vehicle tire  90  is guided through the air nozzle  60  into the casing  10  to push the piston  50  forwards, thereby causing the tensile spring  41  to stretch and the scale  30  to extend out of the first end hole  101  of the casing  10  to an extent indicative of the pressure of the air inside the vehicle tire. 
     FIGS. 9 and 10 show a tire pressure gauge in accordance with a fourth embodiment of the present invention. According to this embodiment, the tire pressure gauge is comprised of a casing  10 , a battery and lamp assembly  20 , a scale  30 , two steel balls  31 , a small spring  31 , a tensile spring  41 , a piston  50 , and an air nozzle  60 . The casing  10  has a first end hole  101 , a second end hole  102 , and a receiving chamber  103  in communication between the first end hole  101  and the second end hole  102 . The scale  30  admits light, having a first end  301 , a second end  302 , and a rod-like scale body  303  connected between the first end  301  and the second end  302 . According to this embodiment, the first end  301  is a screw rod. The battery and lamp assembly  20  is fastened to the second end  302  of the scale  30 , having a touch control switch  70  for on/off control. According to this embodiment, the battery and lamp assembly  21  uses an LED (light emitting diode) as light source. The steel balls  31  are respectively supported on the ends of the small spring  311  and disposed in contact with the inside wall of the casing  10 . The piston  50  is axially slidably mounted in the receiving chamber  103  of the casing  10 . The tensile spring  41  is connected between the rear of the piston  50  and a part inside the air nozzle  60 . The air nozzle  60  is fastened to the second end hole  102  of the casing  10 , and can be installed in the air valve  91  of a vehicle tire  90  to guide air from the vehicle tire  91  to the inside of the tire pressure gauge  100  (see also FIG.  11 ). After installation of the air nozzle  60  in the air valve  91  of the vehicle tire  90 , the air of the vehicle tire is guided through the air nozzle  60  into the inside of the casing  10  to push the piston  50  forwards, thereby causing the piston  50  to switch on the touch control switch  70  of the battery and lamp assembly  20 , the tensile spring  41  to stretch, and the scale  30  to extend out of the first end hole  101  of the casing  10  to an extent indicative of the pressure of the air inside the vehicle tire  90 . After removal of the tire pressure gauge from the air valve  91  of the vehicle tire  90 , the scale  30  is pushed back to the inside of the casing  10 , and the touch control switch  70  is effected by the bottom edge of the piston  50  to switch off the battery and lamp assembly  20 . 
     Although particular embodiments of the invention have been described in detail for the purpose of illustration, various modifications and improvement may be made without departing from the scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.