GB2139329A

GB2139329A - Improvements in or relating to hand-controlled electrically-powered appliances

Info

Publication number: GB2139329A
Application number: GB08306007A
Authority: GB
Inventors: Alan Trelford
Original assignee: Black and Decker Inc
Current assignee: Black and Decker Inc
Priority date: 1983-03-04
Filing date: 1983-03-04
Publication date: 1984-11-07
Also published as: GB2139329B; GB8306007D0

Abstract

A hand-controlled electrically-powered appliance has a handle assembly which, as a safety measure, requires the user to have both hands on the handle 1 to bring the electric motor into operation. The handle assembly incorporates a manually-operable lever 16 which controls energization of the motor and a slide 17 which can interlock mechanically with the lever to prevent accidental operation thereof. The slide 17 has a manually-engageable surface 34 by which the slide can be released from the lever 16 to allow the motor to be energized but the surface 34 is sufficiently spaced from the lever 16 to prevent single-handed operation of both controls. <IMAGE>

Description

SPECIFICATION Improvements in or relating to hand-controlled electrically-powered appliances This invention relates to hand-controlled electrically-powered appliances and has particular reference to electric lawnmowers, lawn scarifiers, lawn edgers, filament trimmers, and cultivators.

Such appliances incorporate a handle by which a user guides and/or operates the appliance. The handle is fitted with a switch that controls energisation of the electric motor that powers the appliance and which is normally spring biassed to an "OFF" position in which the motor is de-energised. Sometimes, a "lock-ofi" button is fitted to the switch and requires to be actuated before the switch can be operated to its "ON" position.

However, even with the "lock-off" button, a user can normally actuate the switch to its "ON" position in a single handed operation and this is potentially dangerous.

Accordingly, it is an object of the present invention to provide hand-controlled electrically-powered appliance fitted with an ON/OFF control that requires operation by both hands of a user.

According to the present invention, a handcontrolled, electrically-powered appliance has a handle assembly including a first control means actuable to energise the motor of the appliance and a second control means mechanically interlocked with the first control means in such manner as to prevent actuation thereof by a user, the second control means having a control surface by means of which the second control is releasable from its mechanical interlock with the first control, the control surface being separated from the first control by a distance sufficient to prevent single-handed operation of both controls.

The first control means may be a pivotallymounted lever lockable against pivotal movement by the second control means which may be a slidably mounted locking member.

The second control means may be resiliently biassed into mechanical interlock with the first control means.

By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompanying drawings of which: Fig. 1 is a front view of part of the embodiment with certain components removed, Fig. 2 is a section on the line ll-ll of Fig. 1, Fig. 3 is a section on the line Ill-Ill of Fig.

1, Fig. 4 is a section on the line IV-IV of Fig.

1, Fig. 5 is a part view in the direction of arrow A of Fig. land Fig. 6 is a section on the line VI-VI of Fig.

1.

Fig. 1 shows a handle member suitable for a lawnmower, lawn scarifier, lawn edger, filament trinmer, garden cultivator or other powered, hand-operated garden appliance.

The handle member comprises a two-part housing of a plastics material. One part only is shown in Fig. 1 at 1, the other part having been removed. The handle member is thus of the so-called clam shell construction.

The part 1 comprises a central body portion 2 with a lower depending channel-shaped stem 3 and laterally-extending, channelshaped handles 4, 5. The portions just described are formed as a one-piece moulding with internal strengthening walls and location bosses. The walls are so disposed as to provide internal compartments 6, 7 and 8 whose purpose is described below.

The bosses 9 are located as shown and are formed with tapered ends and blind bores 10.

The edges of the part 1 have a central upstanding rib 11 which mates with a corresponding groove 1 2 in the other part 1 3 (Fig.

2) of the handle member to locate the parts relatively to one another and to provide a labyrinth type seal to reduce the ingress of moisture and other deleterious matter into the member.

Generally, the part 1 3 of the handle member is of a similar contour to part 1 with internal walls which mate with the walls of part 1 by means of interlocking ribs and grooves similar to the ribs 11 and grooves 1 2 referred to above. The bosses of part 1 3 have tapered bores which engage the tapered ends of the bosses 9 on part 1 and also have axial passages to receive securing screws as will be described later.

The part 1 also has two further bosses 14 and 1 5 which form, respectively, a part of a pivot for a trigger lever 16 of a plastics material and a part of a support for a locking slide 1 also of a plastics material. Boss 1 5 is shown in more detail in Fig. 2 and has a contoured end 18 that engages a socket formed in a co-operating boss 1 9 on the part 13. Sleeves 20 on the bosses 15 and 19 are recessed at their facing ends to mate with laterally projectiing flanges 21 on the locking lever 17.

Trigger lever 1 6 extends outwardly of the part 1 as can be seen in Fig. 1 and is inclined downwardly with respect to handle 4. The trigger lever 1 6 includes a portion 22 located within part 1 and has a curved end face 23 centred on the pivotal axis of the lever 1 7 formed by the boss 14 and the co-operating boss on part 1 3. End face 23 is cut-away as at 24 between the end face and a bearing face 25. Formed integrally with part 1 at a location just above boss 14 is a finger 16a with a hooked outer end as shown in Fig. 6.

The hooked end of the finger 1 6a engages over the adjacent portion of the lever 16 and holds the latter in position in the part 1.

The inclined face 1 6b of the hooked end allows the lever to move the finger away when the lever is first located on the boss 14.

The finger can be manually flexed slightly to disengage the hook shaped end from the lever 16 when it is necessary to remove the latter.

Housed in compartment 6 is a switch indicated as block 26 with an operating member 27 in contact with one end of an actuator rod 28 that extends through a labyrinth seal 29 mounted in the wall of compartment 6 to contact, at its other end, the bearing face 25 with which the end is maintained in contact by a leaf spring 30 secured to the actuator rod 29. Projections 26A moulded integrally with part 1 locate the switch 26 whilst one of the projections has a hook-like extension 26B which locks over the top surface of the switch as shown in Fig. 1 thereby holding the switch in position on part 1.

Locking slide 1 7 is apertured as at 31 and has, at one end, a face 32 curved to mate closely with end face 23 on lever 16, the lower (as seen in Fig. 1) edge of the face 32 having a projecting lip 33 that, when the lever 1 6 and slide 1 7 are in the posititons shown in Fig. 1, engages the cut-away 24 of the end face 23 of lever 16.

On each side of the curved face 32, the end is extended to form a channel within which the end of lever 16 slides.

One such extension is visible in Fig. 1 and is referenced 32A. The interlocking action provided by the channel and the lever end holds the slide 1 7 in position in the part 1.

At its other end, slide 1 7 is upturned and formed with a thumb piece 34 whose outer surface is rounded and ribbed as can be seen from Figs. 4 and 5. The upturned end of slide 1 7 projects through a slot 35 formed between the adjacent edges of the parts 1 and 1 3.

Those edges are also cut-away as at 36 to form a recess along which thumb piece 34 moves as will be described later.

Locking slide 1 7 is formed with a resilient flap 37 that is in contact, at one end, with an internal wall 38 and maintains the slide with its curved end 32 in close engagement with the curved end of lever 16 as shown in Fig. 1 and prevents pivotal movement of the lever.

A drop lead 39 carrying a cord protector 40 that is clamped between the parts 1 and 1 3 of the handle member passes between the walls 41 of a labyrinth clamp located in compartment 8 and is connected to input terminals (not shown) of the switch 26. From the output terminals of the switch 26 extends a lead 42, clamped by the walls 43 of a labyrinth clamp located in compartment 7, that conveys electric power to the driving motor (not shown) of the tool.

The stem 3 of the handle member is detachably secured to one end of a shaft (not shown) whose other end is joined to a housing (not shown) containing the operative parts of the tool.

The components shown in Fig. 1 are located in the positions shown and the necessary electrical connections completed. The part 1 3 is then placed in position over the part 1 and secured thereto by screws passed through the axial passages of the bosses of part 1 3 and screwed into the blind bores 10 in the bosses 9 of part 1.

After connection of the drop lead 37 to a source of electrical power, the tool is ready for use by a user who places one hand on each of the handles 4, 5. With one hand, the user slides the thumb piece 34 to the right (as seen in Fig. 1), that direction being indicated by an arrow 44 (Fig. 5) marked on the rounded upper surface of the thumb piece.

Movement of the locking slide 1 7 takes place against the action of the resilient flap 37. The end faces 23 and 32 move away from one another and the lip 33 disengages the undercut 24.

It is then possible for the user to pivot the lever 1 6 by pulling it towards the handle 4. In so doing, the bearing face 25 presses on the actuator rod 29 and causes the latter to depress the operating member 27 and so operate the switch 26 to its "ON" position and energise the motor.

Any attempt by the user to lift lever 16 towards handle 4 without first operating the locking slide 1 7 will not operate the switch 26 because the lever 16 will be locked against pivotal movement by the locking slide 1 7. Upward pressure on the lever 1 6 to move it towards handle 4 results in downward pressure on the lip 33 but pivotal movement of the slide is prevented by the flanges 21 which come into contact with the adjacent surfaces of the parts 1 and 13.

By spacing the thumb piece 34 sufficiently far away from the lever 16, a user cannot operate both the locking slide 1 7 and the lever 16 with one hand.

Thus, the user must have both hands on the handle member 1 in order to energise the motor and this ensures that the possibility of either of the user's hands coming into contact with moving parts of the operative element of the tool is eliminated. Once the tool is in operation, the user needs to keep both hands on the handle member to control the tool and guide it.

To de-energise the motor, the user simply relaxes the upward pressure on the lever 1 6 and allows the latter to move, under the influence of spring 30 to the position shown in Fig. 1 in which the switch 26 is in its "OFF" position.

Claims

1. A hand-controlled, electrically-powered appliance having a handle assembly including a first control means actuable to energise the motor of the appliance and a second control means mechanically interlocked with the first control means in such manner as to prevent actuation thereof by a user, the second control means having a control surface by means of which the second control is releasable from its mechanical interlock with the first control, the control surface being separated from the first control by a distance sufficient to prevent single-handed operation of both controls.

2. An appliance as claimed in claim 1 in which the first control means includes a pivotally mounted lever that is lockable against pivotal movement by the second control means.

3. An appliance as claimed in claim 2 in which the second control means comprises a slidably mounted locking member.

4. An appliance as claimed in claim 3 in which the lever has an end face contoured to lie on an arc of a circle centred on the pivotal axis of the lever.

5. An appliance as claimed in claim 4 in which the locking member has an end face contoured to mate with the end face on the lever.

6. An appliance as claimed in claim 5 in which the end face on the lever has an undercut, and in which the end face on the member has a projecting lip that mates with the undercut when the member is mechanically interlocked with the lever.

7. An appliance as claimed in any one of the preceding claims in which the second control member is resiliently biassed into mechanical interlock with the first control means.

8. An appliance as claimed in claim 5 or 6 in which the end face of the locking member has a channel-shaped portion within which is engaged part of the end face of the lever.

9. An appliance as claimed in any one of claims 2-8 in which releasable means are provided for retaining the lever on its pivotal axis.

10. A hand-controlled, electrically-powered appliance substantially as herein described with reference to and as illustrated by the accompanying drawings.