Method of mounting a bearing to an air compressor, and air compressor having a bearing mounted by the method

Abstract

A method of mounting a bearing to an air compressor including a shaft element having a first end defining a central cylindrical recess and a second is disclosed, which includes the steps of: fixing the second end of the shaft element to a center of a gear; inserting the first end of the shaft element through a central hole of a bearing to have an annular step of the shaft element abutted an inner ring of the bearing; and hitting the first end of the shaft element by a striking tool with a central pin to form an outwardly extending rim on the first end of the shaft element. With the method, the bearing can be firmly fixed between the outwardly extending rim and the annular step of the shaft element.

Claims

1. An air compressor, comprising: a base frame defining a first mounting hole, which allows a pinion driven by a motor to pass, and a second mounting hole for receiving therein a bearing which includes an outer ring, an inner ring defining a central hole, and a plurality of rolling balls disposed therebetween; a cylinder fixed to or formed integrally with the base frame; an air storage container provided with one or more outlet tubes, and connected and communicated with the cylinder; a gear in mesh with the pinion; and a crank mechanism including a counterweight provided on the gear, a crankpin connected with a piston, and a shaft element having a first end, which defines a central cylindrical recess, and a second end, wherein the second end has a diameter greater than the first end, thus forming an annular step therebetween, the second end of the shaft element being fixed to a center of the gear, the first end of the shaft element being inserted through the central hole of the inner ring of the bearing and being hitted by a striking tool to form an outwardly extending rim on the first end of the shaft element, so that the bearing is firmly fixed between the outwardly extending rim and the annular step of the shaft element.

2. The air compressor of claim 1, wherein a cutout is defined at the second end of the shaft element to form a non-circular portion to be engaged with a non-circular hole defined at the center of the gear.

3. The air compressor of claim 1, wherein the outwardly extending rim is a portion bounded by a first annular tapered surface, an annular convex surface, and a second annular tapered surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a 3-dimensional view of a main structure of an air compressor.

(2) FIG. 2 shows a partially exploded view of the main structure of the air compressor.

(3) FIG. 3 shows a schematic working view of the present invention, wherein a striking tool is employed to hit one end of a shaft element for fixing a bearing in place.

(4) FIG. 4 shows a 3-dimensional view of the striking tool.

(5) FIG. 5 shows a partial sectional view of the main structure of the air compressor, wherein the striking tool is approaching the shaft element to conduct a hitting operation.

(6) FIG. 6 shows a partial sectional view of the main structure of the air compressor, wherein the striking tool has completed the hitting operation.

(7) FIG. 7 shows a partial enlarged sectional view of a part circled in FIG. 6.

(8) FIG. 8 shows a partial exploded view of a main structure of a prior-art air compressor.

(9) FIG. 9 shows a partial exploded view of a main structure of a second prior-art air compressor.

(10) FIG. 10 shows an exploded view of a third prior-art air compressor.

(11) FIG. 11 shows a schematic plan view of the third prior-art air compressor, wherein the motion path of the piston is indicated by dashed lines.

(12) FIG. 12 shows a schematic view of the motion paths of the crankshaft and the crankpin used in a prior-art air compressor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) FIGS. 1 and 2 show a main structure of a typical air compressor, through which a method of mounting a bearing to an air compressor and, more particularly, to a small compressor, will be illustrated. As shown, the air compressor, indicated by reference numeral 2, generally includes a base frame 3, a cylinder 4 with an air storage container 41, a gear 51, and a crank mechanism including a counterweight (not shown), a crankpin 53 connected with a piston (not shown), and a shaft element 52.

(14) The base frame 3 defines a first mounting hole 31, which allows a pinion (not shown) driven by a motor (not shown) to pass, and a second mounting hole 32 for receiving therein a bearing 6 which has an outer ring 61, an inner ring 62, and a plurality of rolling balls 63 disposed therebetween (see FIG. 5).

(15) The cylinder 4 is fixed to or formed integrally with the base frame 3. The air storage container 41 is provided with one or more outlet tubes 411, 412, and connected and communicated with the cylinder 4. The outlet tubes 411, 412 can be connected with a hose, a relief valve, or a pressure gauge.

(16) The gear 51 is disposed in mesh with the pinion (not shown). The counterweight (not shown) is provided on the gear 51. The shaft element 52, which serves as a crankshaft for the air compressor 2, can be made of a metal or alloy and has a first end and a second end opposite to the first end, wherein the second end has a diameter greater than the first end, thus forming an annular step 521 therebetween, the first end of the shaft element 52 has a annular peripheral wall, which defines a central cylindrical recess 524, and on which an annular surface 523 is formed. The shaft element 52 defines a cutout 522 at its second end so that the second end can be shaped as a non-circular portion, such as a semicircular portion. The gear 51 defines at its center a non-circular hole, such as a semicircular hole, corresponding to the non-circular portion formed at the second end of the shaft element 52.

(17) The method of the present invention comprises the following steps:

(18) Step 1: fixing the second end of the shaft element 52 to a center of the gear 51; for example, the second end of the shaft element 52 being snugly fitted into the corresponding hole defined at the center of the gear 51;

(19) Step 2: inserting the first end of the shaft element 52 through the central hole of the bearing 6 to have the annular step 521 of the shaft element 52 abutted the inner ring 62 of the bearing 6 (see FIG. 5); and

(20) Step 3: hitting the first end of the shaft element 52 by a striking tool 7 to form an outwardly extending rim 525 on the first end of the shaft element 52 (see FIG. 6); as a result, the bearing 6 can be firmly fixed between the outwardly extending rim 525 and the annular step 521 of the shaft element 52.

(21) To facilitate forming an outwardly extending rim 525 on the first end of the shaft element 52, it is preferred that, as shown in FIG. 4, the striking tool 7 includes a shank having a press head 71 at one end, which is provided with a central pin 75 having a diameter (A) slightly greater than the diameter (B) of the central cylindrical recess 524 (see FIG. 5) and defining a depression around the central pin 71. An annular surface 72, which has a level lower than the central pin 75, is formed around the depression. More specifically, the depression is delimited by a concave surface 73 at a bottom of the central pin 75, and a conical surface 74 formed between the concave surface 73 and the annular surface 72. In a hitting operation, the central pin 75 can be inserted into the central recess 524 of the shaft element 52 to applied radial force (F) to the annular peripheral wall of the shaft element 52 (see FIG. 7) to facilitate deformation of the top of the cylindrical wall. With the tool, the outwardly extending rim 525 can be formed into a specific shape, as shown in FIG. 7, wherein the outwardly extending rim 525 is a portion of the shaft element 52 bounded by a first annular tapered surface 523′, which is formed by the conical surface 74 of the striking tool 7 urging against the annular surface 523 of the shaft element 52, an annular convex surface 527, which is formed by the concave surface 73 of the striking tool 7 urging against an inner surface of the central cylindrical recess 524 of the shaft element 52 close to the annular surface 523, and a second annular tapered surface 526, which is forced by the central pin 75 to contact the inner ring 62 of the bearing 6.

(22) By using the method of the present invention, the bearing 6 can be firmly mounted with the shaft element 52 in the second mounting hole 32 to prevent possible damages, and the reciprocating motion of the piston 14 can follow its normal straight path. An air compressor, in which the bearing associated with the crankshaft is mounted according to the method of the present invention, the piston can conduct reciprocating motion more smoothly, and thus the performance and service life of the air compressor can be increased.

(23) As a summary, the present invention provides a method of mounting a bearing to an air compressor, and an air compressor, in which a bearing is mounted by using the method. By using a striking tool hitting one end of a shaft element, the bearing can be firmly fixed between an outwardly extending rim and an annular step of the shaft element.

(24) While the invention has been described with reference to the preferred embodiments above, it should be recognized that the preferred embodiments are given for the purpose of illustration only and are not intended to limit the scope of the present invention and that various modifications and changes, which will be apparent to those skilled in the relevant art, may be made without departing from the scope of the invention.