Cutlery – Combined cutlery or combined with ancillary feature – With material-holder or disposal
Patent
1991-05-31
1992-09-15
Watts, Douglas D.
Cutlery
Combined cutlery or combined with ancillary feature
With material-holder or disposal
30390, B23D 4700
Patent
active
051466821
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hand-held circular saw. A circular saw is already known from DE 35 25 092 A1 in which the sawdust is collected in the protective housing of the saw blade and conveyed to an outlet opening. Air is guided into the protective housing from the cooling fan via a hose in order to reinforce the removal of sawdust. This construction is quite expensive because of the necessary additional connection pieces and the separate hose. A considerable pressure loss occurs during the repeated deflection of the flow direction in the hose. Moreover the hose can be a hindrance when working.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a hand-held circular saw which has advantages over the existing hand-held circular saws.
In keeping with these objects, in a hand-held circular saw comprising a housing, a supporting table, and a saw blade driven by a motor and enclosed by a protective housing, an opening for supplying a fan air is connected with a duct which extends in a gearing housing of the circular saw and is connected with an exhaust side of a fan wheel.
The the hand-held circular saw, according to the invention has the advantage that the efficiency of the sawdust removal is improved with the simplest means and without additional structural components and the manufacture and assembly of the saw is simplified. This is achieved in that the fan exhaust air is guided directly into the sawdust duct along the shortest path inside the gearing housing. The fan air ducts are constructed in such a way that no additional parts are required. The outer dimensioning of the saw is not changed, so that handiness is in no way impaired.
In accordance with another feature of the present invention, the hand-held circular saw has a swinging protective hood which overlaps a portion of the saw blade projecting out over the supporting table and is swivelable into the protective housing when sawing, wherein the swinging protective hood forms a defining wall of the duct. It is particularly advantageous to use the swinging protective hood or the saw blade itself as a defining wall for the fan duct. This makes it possible to construct the duct in a very simple manner by means of casting without the need for additional cores or slides or the need to join additional parts during assembly. The sawdust removal is also improved in that a special duct is formed for it in which the sawdust is moved along a defined path. The introduction of the fan exhaust air into the sawdust duct parallel to the flow direction makes optimal use of its energy. The arrangement of the fan air inlet opening acts against possible stoppage in the sawdust duct.
BRIEF DESCRIPTION OF THE DRAWING
Two embodiment examples of the invention are shown in the drawing and explained in more detail in the following description. FIG. 1 shows a longitudinal section through a hand-held circular saw according to line I--I in FIG. 2. FIG. 2 shows a front view of the gearing housing with the cover hood removed, but with swinging protective hood and inserted saw blade. FIG. 3 shows a top view of the protective housing. FIG. 4 shows a second embodiment example in longitudinal section.
DESCRIPTION OF THE EMBODIMENT EXAMPLES
The hand-held circular saw 1 has a housing 2 in which a motor 3 with fan wheel 4 is accommodated. A gearing housing 5 adjoins the housing 2 and receives a gear unit 6 and a saw blade 7. The gearing housing 5, which is preferably cast, is covered by a hood 8 and, together with the latter, forms a protective housing for the saw blade. A swinging protective hood 9 enclosing the saw blade is arranged in the housing 5 so as to be rotatable. The circular saw contacts a work piece 11 with its supporting table 10.
The fan wheel 4 sits directly on the drive shaft 12 of the motor and sucks air into the housing 2 through slots 13. The air is guided along the motor 3 for the purpose of cooling. The fan exhaust air coming from the cooling means is guided further through a duct 14
REFERENCES:
patent: 4414743 (1983-11-01), Pioch et al.
patent: 4675999 (1987-06-01), Ito et al.
Blochle Hans
Eblen Helmut
Gansel Eduard
Kummer Martin
Muller Joachim
Robert & Bosch GmbH
Striker Michael J.
Watts Douglas D.
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