GB2325388A

GB2325388A - Dual-clearance activation device for tools

Info

Publication number: GB2325388A
Application number: GB9801605A
Authority: GB
Inventors: Gianpietro Cazzola; Arrigo Zanella
Original assignee: VALEX SpA
Current assignee: VALEX SpA
Priority date: 1997-05-23
Filing date: 1998-01-26
Publication date: 1998-11-25
Anticipated expiration: 2018-01-26
Also published as: ITVI970075A1; FR2763663B3; GB9801605D0; FR2763663A3; DE29808378U1; GB2325388B; IT1292994B1; ITVI970075A0

Abstract

A dual-clearance activation device, particularly for hedge trimmers, comprising cutting blades (L) which are actuated by an electric motor (M) accommodated in a frame (T), the device further comprising two clearance elements (2, 4), which can be actuated separately in order to act on a motor power switch (S), and braking means (6), which are suitable to act indirectly on the blades when at least one of the clearance elements is released. An oscillating element (7) is operatively coupled to the clearance elements (2, 4) in order to actuate both the switch and the braking means. The oscillating element (7) is supported inside the frame so that it can oscillate and/or perform a translatory motion between a first closed position of the switch, in which the braking means are inactive, and a second open position of the electric switch, in which the braking means are active. The oscillating element comprises a central pivot (8) from which two arms (9, 10) extend, each arm being suitable to interact with a respective clearance element. The braking means (6) consists of a disk or ring made of high-friction material which is keyed to the rotor of the motor.

Description

1 2325388 DUALCLEARANCE ACTIVATION DEVICE FOR TOOLS The present invention

is used in the field of gardening tools and particularly of hedge trimmers and specifically relates to a dual-clearance activation device for the safe starting and stopping of said tools.

in order to comply with currently applicable statutory provisions, currently commercially available electric hedge trimmers and gardening tools must have suitable activation devices which require the operator to use both hands. For this purpose, these devices have two separate controls which must be activated simultaneously in order to start the tool.

These controls are usually of the mechanical type and consists of two elements which can be accessed from outside and which, by means of complicated lever systems for connection and transmission, act separately on a single switch arranged in series in the motor power supply circuit.

This solution entails the drawback that it requires many small components with limited tolerances which must be assembled in rather confined spaces, with consequent difficulties in assembly.

According to another safety standard, tools with unprotected blades must also have a quick stop device, i.e., devices which block the movement of the cutting blades and therefore of the electric motor that drives them within a few seconds of the interruption of the power supply. For this purpose braking means are provided which act on the motor or on moving parts driven by said motor.

The braking devices that are currently in use may be electrical, for example for shorting the rotor, or 2 mechanical, with a freewheel and a blocking control. Electrical braking devices entail the drawbacks of requiring the use of rather complicated wiring, of premature wear of the commutator, and of also requiring the synchronization of both switches.

All current braking devices are rather complicated and expensive to manufacture and assembly.

It would be desirable to be able to provide a dual-control activation device which is highly safe and reliable and has a relatively low cost, which can ensure maximum safety conditions both during starting and during stopping, and which reduces the number of components and the production and assembly complexity of the starting device and of the braking device.

According to the present invention there is provided a dual-clearance activation device for hedge trimmers and similar tools, wherein said device comprises two clearance elements, which can be actuated separately in order to act selectively on at least one motor power supply switch, and braking means which are suitable to act on a rotating part which is connected to the blades when at least one of the clearance elements is released, characterized in that it comprises an oscillating element which is operatively coupled to the clearance elements in order to actuate both said at least one switch and said braking 3 means.

By virtue of this arrangement, the activation device is constituted by a minimal number of low-cost and highly reliable components.

The oscillating element is supported inside the frame so that it can oscillate and/or perform a translatory motion between a first closed position of the switch, in which the braking means are inactive, and a second open position of the electric switch, in which the braking means are active.

Preferably, the oscillating element comprises a central pivot from which two arms protrude substantially at right angles to the axis of the pivot, each arm being suitable to interact with a respective clearance element.

The clearance elements can be constituted by two levers or buttons, the ends whereof are pivoted or slidingly accommodated inside the frame and have internal portions which interact with respective free ends of the arms of the oscillating element.

The central pivot has end portions which are accommodated in slotted seats which are formed in, or rigidly coupled to, the frame so as to allow rotation and translatory motion in a direction which is substantially perpendicular to the axis of the pivot.

Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment of a dual-clearance activation device, particularly for hedge trimmers and similar tools, wherein:

figure 1 is a schematic and partially sectional view of the device according to the present invention, applied to a 4 hedge trimmer, taken along a longitudinal plane; figure 2 is a transverse sectional view of the device of figure 1, taken along the plane II-II; figure 3 is a schematic and partially sectional view of the device of the preceding figures, taken along a longitudinal plane, in a first operating position; figure 4 is a schematic and partially sectional view of the device of figure 3, taken along a longitudinal plane, in a second operating position; figure 5 is a schematic and partially sectional view of the device of figure 3, taken along a longitudinal plane, in a third operating position; figure 6 is a schematic and partially sectional view of the device of figure 3, taken along a longitudinal plane, in a fourth operating position.

With reference to the above figures, a dual-control activation device, generally designated by the reference numeral 1, is applied to a hedge trimmer U comprising an outer frame T formed by two half-shells which internally accommodate an electric motor M for driving cutting blades L. The electric motor M is connected to a power cord by means of a microswitch S provided with a button P.

The device 1 comprises two clearance elements, which consist of a first lever 2, pivoted at 3 along the edge of a rear handle of the frame T, and of a second lever 4, pivoted at 5 to the front part of the f rame T proximate to a grip handle. The levers 2 and 4 can be kept in the inactive position by means of suitable elastic means, for example helical springs. As an alternative, the clearance means can be constituted by buttons slideable along suitable seats and not shown in the drawings.

Braking means are provided which act on a rotating part of the tool which is operatively coupled to the blades of the tool in order to be able to block them within a few seconds of the interruption of the supply of electric power to the motor.

In particular, the braking means are constituted by a disk or ring 6 made of a material with a high friction coefficient, which is keyed on the rotor R of the motor M, preferably anchored to the upper face of the fan V.

According to the invention, there is provided an oscillating element, generally designated by the reference numeral 7, which is actuated by the levers 2, 4 in order to actuate both the switch S and the braking means.

Conveniently, the oscillating element 7 can oscillate and/or perform a translatory motion between a first closed position of the switch S, in which the braking means are inactive, and a second open position of the electric switch, in which the braking means are active.

In particular, the oscillating element 7 is constituted by a central transverse pivot 8, from which two longitudinal arms 9 and 10 extend on opposite sides and in a direction which is substantially perpendicular to the axis of the pivot; said longitudinal arms have curved end portions 11 and 12 which are meant to interact with respective internal portions 13, 14 of the levers 2, 4.

The pivot 8 has end portions 14, 15 which are accommodated in respective slotted seats 16, 17. formed in the internal walls of the frame T or in lateral supports which are anchored thereto. Conveniently, the slotted seats 6 16, 17 are slightly wider than the diameter of the pivot and their main dimension is arranged at right angles to the axis of said pivot.

Elastic means, constituted for example by a leaf spring 18, are interposed between the upper wall of the frame T and the pivot 8 in order to keep the outer surface of the pivot 8 normally pushed toward the disk 6.

Accordingly, in the inactive condition the pivot 8 applies to the disk 6, and therefore to the motor M, a braking action which blocks it within an amount of time which depends on the setting of the spring 18.

By operating both levers 2 and 4, the pivot 8 is moved away in contrast with the action of the spring 18, interrupting the braking action on the disk 6.

The oscillating element 7 is operatively coupled to the button P of the electric switch S by means of an intermediate actuation element.

Said intermediate element is preferably constituted by an L-shaped lever 19 which is pivoted on an axis 20 which is substantially parallel to the axis of the pivot 8. One end of the lever 19 is hinged on the pivot with a certain play, so as to follow the pivot in its rotary and/or translatory motion along the slotted seats 16 and 17, and the opposite end faces the button P.

As an alternative, the intermediate actuation element can be constituted by a protrusion which is formed on, or applied to, one of the arms, not shown in the drawings, and faces directly the button P or the pivot 8 itself.

Accordingly, the simultaneous actuation of the levers 2, 4 causes the rotation of the lever 19 and the pressing of 7 the normally-open button P so as to supply power to the motor M.

In practice, by turning the lever 2 counterclockwise and the lever 4 clockwise, the oscillating element 7 is rotated and shifted, consequently rotating the lever 19 by an extent which is sufficient to compress the button P and therefore start the motor M, as clearly shown by figure 1.

Simultaneously, the actuation of both levers 2, 4 spaces the pivot 8 f rom the disk 6, so as to eliminate the braking action that blocks the motor, as clearly shown in f igure 6.

It is noted that the actuation of only one of the levers 2 and 4, as shown in figures 4 and 5, is not sufficient to move the pivot 8 away from the disk and maintains the braking action thereon besides not actuating the button P on the switch S.

The dual-control activation device is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept expressed by the appended claims. All the details may be replaced with technically equivalent elements which are understood to be equally protected. The materials, the shapes and the dimensions may be any according to requirements.

8

Claims

CLAIMS 1 1. A dual-clearance activation device, particularly for 2 hedge trimmers and similar tools, comprising cutting blades 3 which are actuated by an electric motor accommodated 4 in a frame wherein said device comprises two clearance elements which can be actuated separately in order 6 to act selectively on at least one motor power switch 1 7 and braking means, which are suitable to act on a 8 rotating part which is connected to said blades when 9 at least one of said clearance elements is released, characterized in that it comprises an oscillating element 11 which is operatively coupled to said clearance elements 12 in order to actuate both said at least one switch 13 and said braking means.

1

2. An activation device according to claim 1 2 characterized in 3 supported inside 4 and/or perform a 5 position of said 6 braking means 7 of said at least 8 braking means are 1 2 that said oscillating element is said f rame so that it can oscillate translatory motion between a first closed at least one switch, in which said are inactive, and a second open position one electrical switch, in which said active.

3. An activation device according to claim 1, characterized in that said oscillating element comprises 3 a central pivot from which two arms extend in a 4 substantially perpendicular direction with respect to the axis of the pivot, each arm being adapted to interact with a 6 respective clearance element 1

4. An activation device according to claim 3, 9 2 characterized in that said clearance elements are 3 constituted by two levers or buttons, in which the ends are 4 pivoted or slidingly accommodated within said frame and in which internal portions interact with respective 6 free ends of the arms of said oscillating 7 1

5. An activation device according to claim 3, 2 characterized in that said central pivot has end 3 portions which are accommodated in slotted seats formed in said frame with the possibility of rotating and performing a translatory motion in a direction 6 which is substantially perpendicular to the axis of said 7 pivot

6. An activation device according to claim 5, 2 characterized in that it is provided with elastic contrast 3 means which act on said pivot so as to keep it 4 toward the bottom of said slotted seats and pressed against said rotating part 1

7. An activation device according to claim6, 2 characterized in that said rotating part consists of a 3 disk or ring made of a material having a high friction 4 coefficient which is keyed to the rotor of said motor element 4 1

8. An activation device according to claim 7, 2 characterized in that said braking means consist of an 3 external cylindrical surface of said pivot which faces 4 said disk made of a material having a high friction coefficient.

1

9. An activation device according to claim 5, 2 characterized in that said oscillating element is 3 operatively coupled to the button of said electric 4 switch by means of an intermediate actuation element.

1

10. An activation device according to claim 9, 2 characterized in that said intermediate actuation element is 3 constituted by an L-shaped lever which is pivoted to an 4 axis which is substantially parallel to said pivot and has end portions which interact respectively with said 6 oscillating element and with said button 1

11. An activation device according to claim 9, 2 characterized in that said intermediate connecting element 3 is constituted by a protrusion of said oscillating element 4 which directly faces the button of said electric switch

12. A dual-clearance activation device, particularly 2 for hedge trimmers and similar tools, substantially as 3 herein described with reference to and as illustrated 4 by the accompanying drawings.