# US 7,743,955 B2 · Combustion type power tool having fan

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- Number: US 7,743,955 B2
- Document ID: US7743955B2
- Status: Granted
- Kind: B2
- Application number: 11/028,538
- Filed: 2005-01-05
- Published: 2005-07-21
- Granted: 2010-06-29
- Earliest claimed: 2004-01-16
- Assignees: Hitachi Koki Co., Ltd.
- Inventors: Tomomasa Nishikawa; Haruhisa Fujisawa
- Web page: https://patentgrep.com/patent/US7743955B2

## CPC

- B25C 1/08: operated by combustion pressure
- F02M 29/02: having rotary parts {, e.g. fan wheels}
- F02B 63/02: for hand-held tools
- B25C: HAND-HELD NAILING OR STAPLING TOOLS; MANUALLY OPERATED PORTABLE STAPLING TOOLS (for shoemaking A43D)
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G)

## Abstract

A combustion type power tool having a fan capable of providing a desirable turbulence in a combustion chamber. A fan is rotatably disposed in a combustion chamber and driven by a motor. The fan has fan blades each having a leading edge and a trailing edge. An angle of the leading edge relative to a rotational plane of the fan is approximately equal to an angle of the trailing edge relative to the rotational plane, whereby high degree of turbulence is generated from the position near the leading edge.

## Claims

### Claim 1

A combustion-type power tool providing a combustion chamber comprising:
a housing having one end and a lower side;
a head section closing the one end of the housing and formed with a fuel passage;
a push lever provided to the lower side of the housing and movable upon pushing onto a workpiece;
a cylinder secured to an inside of the housing;
a piston slidably disposed in the cylinder and reciprocally movable in an axial direction of the cylinder, the piston dividing the cylinder into an upper cylinder space above the piston and a lower cylinder space below the piston;
a combustion-chamber frame provided in the housing and movable along the cylinder, the combustion-chamber frame having one end abuttable on and separable from the head section in interlocking relation to the movement of the push lever, a combination of the combustion-chamber frame, the head section and the cylinder space above the piston defining the combustion chamber;
an ignition plug provided at the head section and exposed to the combustion chamber;
a motor; and
a fan rotatably positioned in the combustion chamber and driven by the motor so as to be rotatable about a rotation shaft, the fan having a ring portion extending in a direction perpendicular to the rotation shaft and fan blades each having a leading edge and a trailing edge;
wherein the leading edge of each fan blade extends from the surface of the ring portion in a rotational direction and the trailing edge of each fan blade extends from the surface of the ring portion in a counter rotational direction;
wherein a first angle (α) between the leading edge and the surface of the ring portion is greater than 0° and substantially equal to a second angle (β) between the trailing edge and the surface of the ring portion which is greater than 0°, the first angle (α) being an angle which is not less than 15 degrees; and
wherein the fan is configured so as to enable an increase in degree of turbulence of a combustion gas contained in a fuel injected in the vicinity of the fan and an increase in combustion speed during progress of combustion after ignition of the combustion gas so as to enable an improved operation of the combustion-type power tool.

### Claim 2 (depends on 1)

The combustion-type power tool as claimed in claim 1, wherein the fan comprises from six to eight fan blades.

### Claim 3 (depends on 1)

The combustion-type power tool as claimed in claim 1, wherein each fan blade has a substantially planar shape.

### Claim 4

A combustion-type power tool providing a combustion chamber comprising:
a housing having one end and a lower side;
a head section closing the one end of the housing and formed with a fuel passage;
a push lever provided to the lower side of the housing and movable upon pushing onto a workpiece;
a cylinder secured to an inside of the housing;
a piston slidably disposed in the cylinder and reciprocally movable in an axial direction of the cylinder, the piston dividing the cylinder into an upper cylinder space above the piston and a lower cylinder space below the piston;
a combustion-chamber frame provided in the housing and movable along the cylinder, the combustion-chamber frame having one end abuttable on and separable from the head section in interlocking relation to the movement of the push lever, a combination of the combustion-chamber frame, the head section and the cylinder space above the piston defining the combustion chamber;
an ignition plug provided at the head section and exposed to the combustion chamber;
a motor; and
a fan rotatably positioned in the combustion chamber and driven by the motor so as to be rotatable about a rotation shaft, the fan having a ring portion extending in a direction perpendicular to the rotation shaft and fan blades each having a leading edge and a trailing edge;
wherein the leading edge of each fan blade extends from the surface of the ring portion in a rotational direction and the trailing edge of each fan blade extends from the surface of the ring portion in a counter rotational direction;
wherein a first angle (α) between the leading edge and the surface of the ring portion is greater than 0° and greater than a second angle (β) between the trailing edge and the surface of the ring portion which is greater than 0°, the first angle (α) being an angle which is not less than 15 degrees; and
wherein the fan is configured so as to enable an increase in degree of turbulence of a combustion gas contained in a fuel injected in the vicinity of the fan and an increase in combustion speed during progress of combustion after ignition of the combustion gas so as to enable an improved operation of the combustion-type power tool.

### Claim 5 (depends on 4)

The combustion-type power tool as claimed in claim 4, wherein the fan comprises from 6 to 8 fan blades.