Portable handheld work apparatus
First Claim
1. A portable handheld work apparatus including a motor-driven chain saw, cutoff machine and the like, the work apparatus having a work tool for performing work on a workpiece, the work apparatus comprising:
- a housing;
an internal combustion engine for driving said work tool;
said engine being mounted in said housing;
said housing defining a space from which said engine draws combustion air required for the operation thereof;
a fan wheel disposed in said housing and operatively connected to the engine for generating a cooling-air flow;
said fan wheel having a plurality of vanes having outer respective tips defining a periphery from which the cooling-air flow leaves the fan in a direction tangential to said periphery for cooling said engine;
said housing having a U-shaped channel for conducting the cooling-air flow;
said U-shaped channel having two leg walls and a base wall which conjointly define a U-shaped opening;
said U-shaped channel being disposed so as to face toward said vanes with said U-shaped opening and with said base wall being disposed at a predetermined spacing from said periphery;
said U-shaped channel having a pass-through formed in said base wall at a pregiven spacing downstream from said fan wheel for passing a portion of said cooling-air flow to said space as combustion air for the engine;
said pass-through defining a plane and a center axis perpendicular to said plane;
said U-shaped channel being configured to impart a predetermined direction of flow to said cooling-air flow at the region of said pass-through; and
,said center axis and said predetermined direction of flow conjointly defining an angle β
at said region having a value in a range of approximately 70°
to 180°
.
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Accused Products
Abstract
The invention is directed to a portable handheld work apparatus including a motor-driven chain saw, cutoff machine and the like. The work apparatus includes a housing and an internal combustion engine mounted in the housing for driving a work tool. The housing defines a space from which said engine draws combustion air and a fan wheel is disposed in the housing for generating a cooling-air flow which leaves the fan wheel in a direction tangential to the periphery of the fan wheel for cooling the engine. The housing has a U-shaped channel for conducting the cooling-air flow. The U-shaped channel is disposed so as to face toward the fan wheel with the base wall thereof being disposed at a predetermined spacing from the periphery of the fan wheel. The U-shaped channel has a pass-through formed in the base wall at a pregiven spacing downstream from the fan wheel for passing a portion of the cooling-air flow to the space as combustion air for the engine. The pass-through defines a plane and a center axis perpendicular to the plane. The U-shaped channel is configured to impart a predetermined direction of flow to the cooling-air flow at the region of the pass-through and the center axis and the predetermined direction of flow conjointly define an angle β having a value in a range of approximately 70° to 180°.
24 Citations
15 Claims
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1. A portable handheld work apparatus including a motor-driven chain saw, cutoff machine and the like, the work apparatus having a work tool for performing work on a workpiece, the work apparatus comprising:
-
a housing; an internal combustion engine for driving said work tool; said engine being mounted in said housing; said housing defining a space from which said engine draws combustion air required for the operation thereof; a fan wheel disposed in said housing and operatively connected to the engine for generating a cooling-air flow; said fan wheel having a plurality of vanes having outer respective tips defining a periphery from which the cooling-air flow leaves the fan in a direction tangential to said periphery for cooling said engine; said housing having a U-shaped channel for conducting the cooling-air flow; said U-shaped channel having two leg walls and a base wall which conjointly define a U-shaped opening; said U-shaped channel being disposed so as to face toward said vanes with said U-shaped opening and with said base wall being disposed at a predetermined spacing from said periphery; said U-shaped channel having a pass-through formed in said base wall at a pregiven spacing downstream from said fan wheel for passing a portion of said cooling-air flow to said space as combustion air for the engine; said pass-through defining a plane and a center axis perpendicular to said plane; said U-shaped channel being configured to impart a predetermined direction of flow to said cooling-air flow at the region of said pass-through; and
,said center axis and said predetermined direction of flow conjointly defining an angle β
at said region having a value in a range of approximately 70°
to 180°
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15)
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13. The portable handheld work apparatus of claim 13, said one leg wall ending in a point when viewed in said direction of flow.
Specification