Combustion Type Power Tool Having Sealing Arrangement

Abstract

A combustion type power tool selectively defining a combustion chamber as a result of movement of a combustion chamber frame. A sealing arrangement is provided at a boundary between an outer peripheral section of a chamber head and an inner peripheral portion of an upper portion of the combustion chamber frame. Another sealing arrangement is provided at a boundary between an inner peripheral portion of a lower portion of the combustion chamber frame and an outer peripheral portion of an upper portion of a cylinder. Annular grooves are formed in the outer peripheral section of the chamber head and the outer peripheral portion of the cylinder. Each sealing arrangement is assembled in the annular groove, and includes an endless O-ring and a back-up ring disposed at an inner peripheral side of the O-ring for urging the O-ring radially outwardly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a cross-sectional view of a combustion type power tool according to an embodiment of the present invention, and particularly showing an initial state of the combustion type power tool;

FIG. 2 is a cross-sectional view of the combustion type power tool according to the embodiment, and particularly showing a piston staying at the top dead center;

FIG. 3 is a cross-sectional view of an essential portion of the combustion type power tool according to the embodiment, and particularly showing the piston staying at the bottom dead center;

FIG. 4 is an enlarged cross-sectional view illustrating a seal unit provided between a cylinder and a combustion chamber frame, both shown in FIG. 1;

FIG. 5 is an enlarged cross-sectional view illustrating another seal unit provided between a chamber head and the combustion chamber frame, both shown in FIG. 1;

FIG. 6 is a perspective view of a C-ring used in the seal unit shown in FIGS. 4 and 5;

FIG. 7 is a cross-sectional view showing a part of a conventional combustion type power tool;

FIG. 8 is an enlarged cross-sectional view illustrating a seal unit in accordance with a related art and to be provided between a cylinder and a combustion chamber frame in the conventional combustion type power tool shown in FIG. 7;

FIG. 9 is an enlarged cross-sectional view illustrating the seal unit at a time when a piston is moved toward its top dead center from its bottom dead center in accordance with the related art and to be provided between the cylinder and the combustion chamber frame, in the conventional combustion type power tool shown in FIG. 7;

FIG. 10 is a cross-sectional view illustrating the seal unit, taken long line X-X in FIG. 9;

FIG. 11 is an enlarged cross-sectional view illustrating another seal unit in accordance with a related art and to be provided between a chamber head and the combustion chamber frame in the conventional combustion type power tool shown in FIG. 7;

FIG. 12 is an enlarged cross-sectional view showing still another seal unit in accordance with a related art and including iron rings provided between a cylinder and a combustion chamber frame; and

FIG. 13 is a perspective view showing one of the iron rings shown in FIG. 12.

Claims

1. A combustion type power tool comprising: a housing having one end and another end;a chamber head fixed to the one end of the housing;a cylinder fixedly disposed in the housing;a combustion chamber frame movable toward and away from the chamber head within the housing, a combustion chamber being defined when the combustion chamber frame is in abutment with the chamber head, at least one of the chamber head and the cylinder being formed with an annular groove; and,at least one sealing unit assembled in the annular groove and comprising a sealing member, and a back-up ring disposed in contact with the sealing member, the back-up ring providing a radially outward expansion force for urging the sealing member radially outwardly.

2. The combustion type power tool as claimed in claim 1, wherein the sealing member is an O-ring.

3. The combustion type power tool as claimed in claim 2, wherein the O-ring is made from a rubber, and wherein the back-up ring has a C-shape configuration forming a slit extending in a radial direction thereof.

4. The combustion type power tool as claimed in claim 3, wherein the O-ring has a circular cross-section.

5. The combustion type power tool as claimed in claim 3, wherein the back-up ring is made from a metal.

6. The combustion type power tool as claimed in claim 5, wherein the back-up ring is made from steel.

7. the combustion type power tool as claimed in claim 1, wherein the chamber head has an outer peripheral part serving as a first region; and wherein the cylinder has an outer peripheral part serving as a second region; andwherein the combustion chamber frame has a third region to be faced with the first region and a fourth region to be faced with the second region, the annular groove being formed at least one of the first region and the second region.

8. The combustion type power tool as claimed in claim 7, wherein the first region is formed with a first annular groove, and the second region is formed with a second annular groove; and wherein the sealing unit comprises a first sealing unit assembled in the first annular groove, and a second sealing unit assembled in the second annular groove.

9. The combustion type power tool as claimed in claim 1, further comprises: a piston reciprocally slidably movably disposed in the cylinder;a driver blade extending from the piston and at a position opposite to the chamber head with respect to the piston;a push lever movably disposed at a side of the another end of the housing, the push lever having a tip end to be in contact with a workpiece, the combustion chamber frame being movable in interlocking relation to the movement of the push lever; andan ignition plug exposed to the combustion chamber for igniting a combustible gas introduced into the combustion chamber.