Piston structure for an air pump

A piston for an air pump is disclosed. The piston has a piston rod having a connecting axle hole for positioning a bearing, which is protected with a bearing protection cap. The bearing is firmly secured within the axle hole.

BACKGROUND OF THE INVENTION

(a) Technical Field of the Invention

The present invention relates to piston, and in particular, to a piston mounted within a cylinder.

(b) Description of the Prior Art

Pistons used in conventional small size or portable pump employ TEFLON, a high temperature resistance, wear-resistance material as a material for rings of the pistons TEFLON is an extremely high plasticizing material and the rings are mounted or secured at the outer surface of the piston. The drawbacks of such structure are that, for example, stability of the structure is not sufficient, and air-sealing is poor, which causes non-smooth rotating, air leakage, air compression ratio being insufficient. Additionally, the longevity of the piston is affected.

Currently, another type of conventional piston, as shown inFIG. 1has a recessed circular slot A2at the external edge of the piston A1, and the recessed circular slot A2is mounted with a circular gas ring A3. There is a seal between the ring A3and the cylinder wall such that high speed reciprocation operation of the piston will achieve the objective of the air compression and air-filling. However, the drawbacks of this conventional structure are that(1) the binding force between the circular ring and the piston slot is weak and therefore, the circular ring is dislocated or biased;(2) the tolerance and precision between the circular ring and the piston circular slot has to be accurate. Thus, the inaccurately of the tolerance will affect the stability of the reciprocation process;(3) if the tolerance is too great motor may be affected and high heat and expansion will occur;(4) if the tolerance is too small, the air compression is insufficient and air leakage will occur; and(5) as shown inFIG. 1, if the bearing A4is dislocated or biased, the air pump will be damaged and the longevity of the pump is affected.

SUMMARY OF THE INVENTION

The primary purpose of the present invention is to provide a piston for an air pump which mitigates the above-mentioned drawbacks.

Yet still another object of the present invention is to provide a piston for an air pump comprising a valve sealing plate, an upper piston plate, an air ring, a piston rod, locking component, a bearing and a bearing protection cap, characterized in that the valve sealing plate is flatly mounted by a pegging plate and a peg onto a venting hole provided on the upper piston plate; wherein the upper piston plate has a bottom with an external edge having a circular protruded edge, and the piston plate has a row of venting holes in combination with the valve sealing plate, and the bottom section of the upper piston plate is provided with screw nut for combination with a recess at the lower piston plate, and the locking component is used to lock the lower piston plate; the air ring is mounted between the upper and the lower piston plate and has a hollow bowl cavity and is made from temperature resistant and wear-resistant material, and the diameter of the air ring is larger than that of the inner wall of the cylinder, and the external edge is a converging face inwardly inclined; the piston rod is formed together with the lower piston plate and the axle hole at the bottom section of the lower piston plate; and the lower piston late and the upper piston plate are locked with the locking component, and the interior of the piston rod is a recessed positioning slot and the two ends of the positioning slot is a through hole; the external side of the recessed slot is provided with at least one inlet, and the lower section of the piston rod is an axle hole having a blocking edge at the inner side, and the external edge of the axle hole is locked and protected with a bearing protection cap to protect the bearing positioned within the axle hole; the bearing is positioned within the axle hole of the piston rod; and the bearing protection cap locks the external edge of the axle hole of the piston rod and the protruded edge of the protection cap urges the bearing within the axle hole.

Still a further object of the present invention is to provide a piston structure for an air pump, wherein the upper and the lower piston plates form into an interior to provide air convection.

Another further object of the present invention is to provide a piston structure for an air pump, wherein the external edge of the protruded edge of the bearing protection cap and the bearing form into an effective space for the application of a lubricant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 2 and 3, there is shown a piston for an air pump of the present invention comprising a valve sealing plate1, an upper piston plate2, an air ring3, a piston rod4, locking component5, a bearing6and a bearing protection cap7. One side of the valve sealing plate1is provided with a pegging plate11and a peg12which can cover the valve sealing plate1onto the venting hole21on the upper piston plate2, such that in the course of high speed reciprocation movement of the piston, the opening and closing of the sealing plate1cause venting and sealing. The present piston has an upper piston plate2and a lower piston plate41. The upper piston plate2has a valve sealing plate1and the lower piston plate41is in combination with the axle hole42at the lower section of the piston rod4. The air ring3is positioned between the upper piston plate2and the lower piston plate41and the locking component5, passing through the through hole411at the bottom section of the lower piston plate41lock the lower piston plate41onto the positioning screw rod22of the upper piston plate2such that the air ring3is secured between the upper and the lower piston plates2,41, and the wall of the cylinder is elastically sealed with respect to reciprocation movement.

The inner edge of the air ring3is a hollow bowl shape which is made from high temperature resistant and wear resistant material, such as TEFLON, and the external diameter of the air ring3is slightly larger than the diameter of the cylinder, and the external edge is a converging face which is inwardly inclined. After it is combined with the internal wall of the cylinder, the internal wall of the cylinder is elastically sealed.

As shown inFIG. 4, there is shown a top view of the lower piston plate41, and the interior of the lower piston plate41has a recessed slot410and a through hole411at the two ends thereof. The external side of the lower piston plate41has at least one inlet412. As shown inFIG. 5, there is shown the top view at the bottom section of the upper piston plate2. The external edge is a pressing protruded edge23, and the bottom section is a protruded positioning screw rod22so that it will correspond to the recessed slot410and the through hole411, and the locking component5is employed for locking the upper piston plate2. The air ring3with the aid of the protruded edge is effectively secured.

Referring toFIG. 5, after the upper piston plate2and the lower piston plate41are locked at the air ring, the upward and downward reciprocation movement can synchronously withdraw air and expel air. The interiors of the upper and lower piston plate are formed into an effective air stream space20. Thus, when the piston is reciprocating at a high speed, the upper stroke will cause the valve sealing plate1to seal and air is compressed out via the piston, and the down stroke of the piston will withdraw air via the inlet412of the piston41. The air stream space20forms into a pressure which is effectively pushed open the valve sealing plate1. The high speed reciprocation movement allows the valve sealing plate1to operate effectively and the amount of withdrawal air is increased relatively, which improves the flow rate of air and the compression ratio of the cylinder. Thus, the air-filling rate of the air pump is enhanced.

ReferringFIG. 6, the lower section of the piston rod4has an axle hole42for holding the bearing6. The inner side of the axle hole42is a blocking edge42which can be positioned the bearing6. The external edge of the axle hole42is a bearing protection cap7which is locked by a locking component, and the protruded face71at the internal of the protection cap7can tightly urge the bearing6within the axle hole42such that the bearing6will be positioned within the axle hole42. This will eliminate the dislocation of the bearing6at high reciprocation speed. At the same time, the effective gap formed between the external edge of the protruded edge71of the protection cap and the bearing is used for the application of a lubricant, which will lubricate the bearing and effectively improves high efficient operation.