Air pressure measuring pen

An air pressure measuring pen of a neat and satisfactory design is provided. The pen includes a transparent hollow pen tube having a top end and a bottom end, a clipping cover connected to the top end and having an exhaust valve, a check valve and a measuring head, a spring urging in the pen tube apart a stopping medium and a piston in the pen tube, an ink holder, and an ink holder positioner connected to the bottom end.

BACKGROUND OF THE INVENTION 
The present invention relates to a pen, and more particularly to an air 
pressure measuring pen. 
The conventional air pressure measuring pen, as shown in FIG. 1, includes a 
pen tube 1, a measuring head 2 mounted on tube 1, a piston 3 received in 
tube 1 also receiving therein a sealing piece 4, a spring 5 mounted 
bwtween piston 3 and piece 4, an indicating rod 6 capable of protruding 
out of tube 1 and having an outer scale 7 and an ink holder 8 therein, and 
a threaded fixture 9 respectively fixing rod 6 and holder 8 in tube 1 and 
rod 1. In use, head 2 is inserted upon an air valve of a tire, the 
pressurized air in the tire will protrude, through piston 3, sealing piece 
4 and spring 5, rod 6 out of tube 1 to show the air pressure in the tire. 
Such air pressure measuring pen must have the tube 1 large enough to 
receive therein rod 6 requiring to be troublesomely provided with an inner 
long hole to receive therein ink holder 8. In order to measure the air 
pressure and to write with the present pen, fixture 9 must first be 
unscrewed from tube 1. In addition, when rod 6 is protruded out of tube 1 
by the tire air pressure, rod 6 easily gets inadvertently retracted into 
tube 1 to force the user to measure the air pressure anew. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide an air 
pressure measuring pen having a pen tube having a reduced diameter. 
It is further an object of the present invention to provide an air pressure 
measuring pen having a neat design. 
It is additional an object of the present invention to provide an air 
pressure measuring pen capable of optionally keeping measured air 
pressure. 
According to the present invention, an air pressure measuring pen includes 
a hollow pen tube having a top end and a bottom end, an ink holder, an ink 
holder positioner connected to the bottom end and a clipping cover 
connected to the top end, in which the measuring pen further has a 
stopping medium received in the bottom end, a piston received in the pen 
tube, a spring urging apart the medium and the piston, and a check valve 
received in the clipping cover and cooperating with the piston to form 
therebetween an air chamber; the clipping cover includes an exhausting 
valve capable of communicating with the air chamber, a measuring head at a 
top thereof, an actuating protrusion mounted in the measuring head, an air 
passage provided around the protrusion and communicable with the air 
chamber so that when the head is inserted upon an air valve of a tire an 
air in the tire will pass through the passage into the air chamber; and 
the pen tube is transparent and includes a lower vent and an outer 
pressure scale. 
The present invention may best be understood through the following 
description with reference to the accompanying drawings, in which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 2-5, an air pressure measuring pen 10 according to 
the present invention includes a hollow pen tube 11, an ink holder 
positioner 12 connected to the bottom end of tube 11 and receiving therein 
an ink holder 13, a clipping cover 14 connected to the top end of tube 11, 
a top cover 15 covering on cover 14 and fixing thereon an eraser 16, and a 
bottom cover 17 covering on positioner 12. 
Pen tube 11 is transparent and includes an outer scale 20 and a lower 
downwardly enlarging tapered inner portion 21. A hollow connector 22 is 
received in pen tube 11 and includes a tapered part 23 matching with 
tapered portion 21, a male screw thread 25 engaging with a female screw 
thread 24 in postioner 12, and a female screw thread 26 in its top wall 
27. A stopping medium includes a plug 30 having a lower male screw thread 
31 engaging with female thread 26, and a stopper 33 placed on a shoulder 
formed by tapered portion 21 and having a through hole 35 protruding 
therethrough an upper protrusion 36 of plug 30. Pen tube 11 further 
receives therein a piston 38 and a spring 40 mounted between stopper 33 
and piston 38 which further includes a lower shoulder 41 and an annular 
groove 43 sleeving therein an indicating ring 42 preferably having a red 
outer surface. Tube 11 also has a lower vent 44 so that the air between 
stopper 33 and piston 38 can be freely discharged therefrom. 
Clipping cover 14 includes a clipping medium 51 and a clipping body 50 
which further includes a receiving room 52, and receives therein a check 
valve seat 53 and a circular baffle 54 having two through holes 58, 59 and 
a recess 60. Seat 53 includes an upper shoulder 55 mounting thereon a 
sealing ring 56, an axial hole 57 having a tubular portion 64, and a lower 
end matched in recess 60. Seat 53 and baffle 54 mount therebetween a ball 
62 and a spring 63 urging ball 62 against tubular portion 64. Body 50 
further includes a measuring head 70, an inner shoulder 71, an actuating 
protrusion 72, an air passage 73 provided around protrusion 72, and an 
annular pad 74 mounted on shoulder 71. 
Piston 38 and baffle 54 form therebetween an air chamber 75. Body 50 
includes a threaded mounting hole 77 threadedly engaging thereto a male 
thread 81 of an exhausting valve seat 80 having a through hole 83 and an 
end surface 82 having a radial through groove 84. A valve body 85 of the 
exhausting valve is generally mounted in seat 80 and includes a 
diametrally relatively larger portion 87 sleeving thereon an annular 
washer 88 and capable of protruding out of through hole 83, an 
intermediate annular flange 89, and a diametrally relatively smaller 
portion 91 sleeving thereon a spring 90 mounted between flange 89 and the 
tube top end having a groove 76 so that spring 90 always urges washer 88 
to seal through hole 83 and when large portion 87 is inwardly pushed, the 
air in chamber 75 will pass through groove 76 and hole 83 to be 
discharged. If seat 80 needs to be position-adjusted, a tool capable of 
engaging in groove 84 can be used. 
In use, top cover 15 is first removed and measuring head 70 is inserted 
upon a tire air valve a pressurized air passing through air passage 73, 
axial hole 57 and holes 58, 59 into air chamber 75 to downwardly urge 
piston 38 and spring 40 to a balanced extent so that indicating ring 42 
will show the tire air pressure on scale 20. After measuring head 70 is 
removed from the tire air valve, spring 63 and ball 62 will block up hole 
57 so that piston 38 and ring 42 will keep positioned in the displaced 
position. If the measured air pressure is no more needed, larger portion 
87 is inwardly pushed to discharge the air in chamber 75 out of through 
hole 83 so that spring 40 will return piston 38 into the non-actuated 
position and a new measurement can be taken place.