EP1995027A1 - A safety system for preventing tool engagement in electric saws when the motor rotates - Google Patents
A safety system for preventing tool engagement in electric saws when the motor rotates Download PDFInfo
- Publication number
- EP1995027A1 EP1995027A1 EP07425306A EP07425306A EP1995027A1 EP 1995027 A1 EP1995027 A1 EP 1995027A1 EP 07425306 A EP07425306 A EP 07425306A EP 07425306 A EP07425306 A EP 07425306A EP 1995027 A1 EP1995027 A1 EP 1995027A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- tie rod
- engagement
- lever
- rotation
- plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
- B27B17/00—Chain saws; Equipment therefor
- B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
- B27B17/10—Transmission clutches specially designed for chain saws
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Milling, Drilling, And Turning Of Wood (AREA)
- Sawing (AREA)
Abstract
Description
- A common electric saw comprises a chain-tool which runs on a chain-guide solidly constrained to the casing of the saw, powered by an electric motor set in motion by closing a switch activated by a lever located below the gripping handle solidly constrained to the casing.
- Drive to the shaft on which the pinion moving the chain is keyed is transmitted by a frontal mechanical engagement, the mobile part of which is associated to a plate, such as a disc, which when rotating runs on inclined guides such that the rotation is transduced into a translation about the rotation axis of the plate.
- The rotation of the disc that determines the engagement occurs during movement of the electric saw starting lever.
- The problem which obtains is that a further engagement is impossible, after a disengagement, if the shaft of the electric motor is still rotating, as this would case a rapid deterioration of the engaging mechanism itself, with very loud noise emission.
- The aim of the present invention is to create a disengagement system for electric saws which prevents the above-described drawbacks, in the context of a simple and inexpensive solution.
- The aim is attained by the invention by means of an equipment having characteristics as recited in claim 1.
- The dependent claims recite further characteristics of the equipment which improve the efficiency and functionality thereof.
- The functional and constructional advantages and characteristics of the invention will better emerge from the detailed description that follows, with the aid of the accompanying figures of the drawings, of a preferred embodiment thereof, provided purely by way of non-limiting example, in which:
-
figure 1 is an internal lateral view of the electric saw illustrating the activating and disengaging organs, with the machine stationary; -
figure 2 is section II-II offigure 1 ; -
figure 3 is the view offigure 1 , but with the activating and disengaging organs in the machine-on position, and with the starting lever completely raised;figure 4 is the view offigure 1 , but with the activating and control organs in an intermediate position; -
figure 5 is the view offigure 1 , but with the activating and control organs in a final disengaged position, with the electric motor still turning by force of inertia. - The figures show a casing 1 comprising a
handle 40, internally of which casing 1 alever 2 is hinged to apivot 3. - A con rod 4 is hinged at the central part of the
lever 2, to which con rod 4 a tie rod 9 is connected. - The end of the con rod 4 opposite the hinge slides, by means of a
cam follower wheel 7, on acam 8 which is solidly constrained to the handle. - The
cam follower wheel 7 of the con rod 4 is kept pressed against thecam 8 by atraction spring 22 constrained at an end thereof to the con rod 4 and at the other end thereof to thehousing 23 of thelever 2. - At the end of the con rod 4 which is close to the cam, a tie rod 9 connects the con rod 4 to a
lug 14 of adisc 16. - The
lug 14 exhibits a specially-shaped slot 13 provided with atooth 12 to which the hookedend 11 of the tie rod 9 is hooked. - The tie rod 9 exhibits a
projection 10 at about the median line thereof. Wings 15 project from the edge of thedisc 16. - An
appendage 19 is fashioned on the lower part of thedisc 16, to which appendage 19 atraction spring 20 is engaged, whichtraction spring 20 is fixed to apivot 21 solidly constrained to the casing 1. - The
wings 15 of thedisc 16 rest oninclined surfaces 17 such that rotations of thedisc 16 are transformed into axial translations to which the activation of the frontal engagement corresponds. - By activating the
lever 2 in an upwards direction, thelever 2 performs a clockwise rotating motion which determines an anticlockwise rotation of the con rod 4, and by means of the tie rod 9 an anticlockwise rotation of thelug 14 and thedisc 16. - The inclined surfaces of the
wings 15 and thesurfaces 17, running on one another, cause an axial movement of the hub to which they are constrained. The axial movement causes mechanical engagement of the shaft moved by the motor to the shaft activating the pinion moving the tool chain. - The final tract of the
lever 2 movement activates anelectric switch 24 which sets the motor in motion. - A
small plate 25 is fixed to the casing 1 at about the position of theprojection 10, and below the tie rod 9. Thesmall plate 25 is freely rotatable about an axis thereof, and a small eccentric pivot 26 is fixed to the external end thereof, which small eccentric pivot 26 is kept pressed against the tie rod 9 by acoil spring 27 which is coaxial to theplate 25 axis. - The
spring 27, as it acts on thetooth 29 forces it against thestop 28 solidly constrained to the casing 1 such that theplate 25 can rotate only in an anticlockwise direction when it comes into contact with theprojection 10 of the tie rod 9. - In this way, when the tie rod 9 displaces towards the left, it is not raised by the
projection 10, while when it is moved towards the right it is raised in order to pass over the pivot 26 and at the same time it disengages from thetooth 12 of theslot 13. - The lower part of the
lever 2 exhibits astriker 30 at an end thereof. - Close to the
striker 30 the casing 1 bears amobile appendage 31 fixed to the end of anaxis 32 which is rotatingly supported by the casing 1. - At the opposite end of the axis 32 a
blade 34, facing thecooling fan blades 35 of the electric motor, is kept in a proximal position to the fan, illustrated infigure 1 , by elastic means (not illustrated). - In this condition the fan is stationary, and the
mobile appendage 31 does not prevent thelever 2 from being displaced upwards to activate the front engagement of the electric motor. - When the electric motor is functioning, it sets the
fan 35 in rotation too, whichfan 35 creates a flow of air that strikes theblade 34, causing it to rotate in a clockwise direction such that theappendage 31 is arranged in front of thestriker 30, thus preventing thelever 2 from being displaced upwards to activate the frontal engagement mechanism of the electric motor. - The invention functions as follows. Starting from the rest position illustrated in
figure 1 , the operator displaces thelever 2 upwards, up until it causes theswitch 24 to close and the electric motor to start up. - During the upwards displacing of the
lever 2 the tie rod 9 rotates thedisc 16 towards the left, activating the frontal engagement which transmits motion to the chain. - This is the situation illustrated in
figure 3 . - If the operator even partially releases the
lever 2, thedisc 16, by action of thespring 20, rotates in a clockwise direction up until theprojection 10, in order to overcome the pivot 26, raises the tie rod 9, causing the unhooking of the end thereof from thetooth 12. - In this way the
disc 16 can rotate completely in a clockwise direction, deactivating the frontal engagement between the electric motor and the chain. - A subsequent activation upwards of the
lever 2 is not transmitted to the engagement, as thedisc 16 stays in position and the end of the rod 9 moves in theslot 13. - The end of the rod 9 will not re-hook with the
tooth 12, and the engagement cannot be restored, until thelever 2 is returned to the fully-lowered position thereof. - If, at the moment of full release downwards of the
lever 2, the electric motor is still rotating through inertia, thestriker 30 is kept in front of theappendage 31, preventing thelever 2 from being activated upwards to re-start the motor. This situation persists such until the motor has completely stopped. - This gives the certainty that once the
lever 2 has been released downwards, any restarting of the motor can occur only with the frontal engagement between the motor and the saw completely disengaged, or with the motor completely stationary.
Claims (6)
- A safety system for preventing engagement of a tool in electric saws if an electric motor of the saw is not stationary, in which engagement of the tool is achieved by axially displacing a first part of an engagement mechanism towards a second part of the engagement mechanism, the axial movement of the first part of the engagement mechanism being achieved by rotation of a plate mounted on inclined guides, in contrast with elastic means, the rotation being imposed on the plate by an activating lever via a tie rod hooked to a tooth fashioned in a circumferential slot of the plate, characterised in that it comprises a stop device of the displacement of the activating lever from a rest position thereof, which stop device is maintained in a blocking position of the activating lever by means which are sensitive to rotation of the motor, which means act in contrast with elastic means which maintain the stop device in a position thereof enabling activation of the lever when the electric motor is stationary.
- The system of claim 1, characterised in that the means which are sensitive to rotation of the motor comprise a cooling fan of the motor which generates a flow of air which pushes the stop device into an active blocking position thereof.
- The system of claim 2, characterised in that the blocking device is keyed on an axis which comprises a mobile appendage which projects into a direction flow of air generated by the cooling fan.
- The safety system of claim 1, characterised in that it comprises means for unhooking the tie rod of the plate if the activating lever is activated before the rest position is reached.
- The system of claim 4, characterised in that the means for unhooking the tie rod comprise a projection fashioned on the tie rod, and a striker plate kept elastically pressed against the tie rod, which striker plate lowers when passed over by the projection of the tie rod in a direction causing engagement of the tool, and raises the tie rod when the projection passes over in an opposite direction, the raising of the tie rod causing unhooking of the tie rod from the tooth of the plate.
- The system of claim 5, characterised in that the projection is a V-shaped bend fashioned in the tie rod.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP20070425306 EP1995027B1 (en) | 2007-05-21 | 2007-05-21 | A safety system for preventing tool engagement in electric saws when the motor rotates |
DE200760009057 DE602007009057D1 (en) | 2007-05-21 | 2007-05-21 | Safety system to prevent tool drive in electric saws when the motor is turning |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP20070425306 EP1995027B1 (en) | 2007-05-21 | 2007-05-21 | A safety system for preventing tool engagement in electric saws when the motor rotates |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1995027A1 true EP1995027A1 (en) | 2008-11-26 |
EP1995027B1 EP1995027B1 (en) | 2010-09-08 |
Family
ID=38573079
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20070425306 Expired - Fee Related EP1995027B1 (en) | 2007-05-21 | 2007-05-21 | A safety system for preventing tool engagement in electric saws when the motor rotates |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP1995027B1 (en) |
DE (1) | DE602007009057D1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3237739B1 (en) | 2014-12-23 | 2020-05-13 | Husqvarna AB | Internal combustion engine and method for safe starting the same |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10359873B3 (en) * | 2003-12-18 | 2005-05-19 | Mogatec Moderne Gartentechnik Gmbh | Safety interlock for chainsaw prevents operation of drive clutch unless air flap for flow channel around outside of fan wheel is in given position |
-
2007
- 2007-05-21 DE DE200760009057 patent/DE602007009057D1/en active Active
- 2007-05-21 EP EP20070425306 patent/EP1995027B1/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10359873B3 (en) * | 2003-12-18 | 2005-05-19 | Mogatec Moderne Gartentechnik Gmbh | Safety interlock for chainsaw prevents operation of drive clutch unless air flap for flow channel around outside of fan wheel is in given position |
Also Published As
Publication number | Publication date |
---|---|
EP1995027B1 (en) | 2010-09-08 |
DE602007009057D1 (en) | 2010-10-21 |
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