PISTON

Abstract

A piston for a hammer drill is a flat piston made from sintered steel. The piston can be impregnated with a lubricant.

Claims

1. A piston for a hammer drill, wherein the piston is a flat piston comprising sintered steel.

2. The piston of claim 1, wherein the piston is impregnated with a lubricant.

3. The piston of claim 2, wherein the lubricant is oil.

4. The piston of claim 1, wherein the piston comprises a front circular disk having a flat front surface, further comprising: a circumferential groove extending around the edge of the circular disk; a circular peripheral wall extending rearwardly from the edge of the circular disk perpendicularly to the plane of the circular disk; two straight sections formed on two opposite sides of the circular peripheral wall; two frames formed on the two straight sections; and two apertures each formed through a corresponding one of the frames and straight sections.

5. A hammer drill comprising: a housing; a tool holder mounted on the housing capable of holding a cutting tool; a motor mounted within the housing; and a hammer mechanism comprising: a cylinder; a piston mounted in the cylinder and reciprocatingly driven along a longitudinal axis by the motor, wherein the piston is a flat piston comprising sintered steel; a ram mounted in the cylinder forward of the piston and reciprocatingly driven along the longitudinal axis by the piston via an air spring; and a beat piece supported in an axially slideable manner along the longitudinal axis within a beat piece support structure, wherein, during a normal operation of the hammer mechanism, the beat piece is repetitively struck by the ram and transfers impacts to a cutting tool held by the tool holder.

6. The hammer drill of claim 5, wherein the cylinder is made from steel.

7. The hammer drill of claim 5, wherein the cylinder is formed as a part of a spindle.

8. The hammer drill of claim 5, wherein the cylinder is made from sintered steel.

9. The hammer drill of claim 8, wherein the cylinder is impregnated with a lubricant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.

[0039] FIG. 1 shows a side view of a prior art hammer drill;

[0040] FIG. 2 shows a cross sectional view of the hammer mechanism with the ram in a position where it can freely slide within the spindle;

[0041] FIG. 3 shows a cross sectional view of the hammer mechanism with the ram in the ram catcher and the beat piece sliding in the spindle;

[0042] FIG. 4 shows a cross sectional view of the hammer mechanism with the ram in the ram catcher and the beat piece in its furthest forward position in the spindle;

[0043] FIG. 5 shows the beat piece;

[0044] FIG. 6 shows a vertical cross-sectional view of a hammer drill in accordance with the present invention;

[0045] FIG. 7 shows a rear view of the piston shown in FIG. 6;

[0046] FIG. 8 shows a side view of the piston shown in FIG. 6;

[0047] FIG. 9 shows a rear perspective view of the piston shown in FIG. 6; and

[0048] FIG. 10 shows a front perspective view of the piston shown in FIG. 6.

[0049] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0050] An embodiment of the present invention will now be described with reference to FIGS. 6 to 10.

[0051] FIG. 6 shows a cross section view of hammer drill having a piston 204 in accordance with the present invention. Where the same features in the embodiment shown in FIG. 6 are shown in the prior art example described above, the same reference numbers are used and the same description is applicable. The only difference between the prior art design and the embodiment is the design of the piston 204 and spindle 150.

[0052] Referring to FIGS. 7 to 10, the piston 204 is a flat piston and comprises a front circular disk 300 having flat front surface 302. A circumferential groove 304 extends around the edge of the circular disk 300. A circular peripheral wall 306 extends rearwardly from the edge of the circular disk 300, perpendicularly to the plane of the circular disk 300. Two straight sections 308 are formed on two opposite sides of the wall 306. A frame 310 is formed on each straight section 308. An aperture 314 is formed through each frame 310 and straight section 308. The piston 204 is manufactured in a one-piece construction from sintered steel which has been impregnated with a lubricant such as oil.

[0053] The rubber O ring 208 locates in the groove 304. The piston 204 is mounted inside of the spindle 150 and connected to the crank shaft 206 via a cross pin 312.

[0054] The design of the spindle 150 is different from the prior art design described above in that it manufactured from steel. The coefficient of expansion of the steel spindle 150 is the same as that of the sintered flat piston 204.

[0055] Alternatively, the spindle 150 is manufactured from sintered steel. Ideally, it would be manufactured in a one-piece construction. The coefficient of expansion of the sintered steel spindle 150 is the same as that of the sintered flat piston 204. The sintered steel spindle 150 can impregnated with a lubricant such as oil.

[0056] The sintered steel piston 204 and/or sintered steel spindle 150 can be manufactured by using a sintering process and then submersing them in a lubricant to impregnate the piston and/or spindle with the lubricant.

[0057] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.