GB2333435A - Rotary lawnmowers - Google Patents

Abstract

A rotary lawnmower has an outlet passage through which grass cuttings are ejected from a cutting chamber. A safety flap 36 is movable against a resilient bias from a partially open position to a fully open position relative to the outlet passage. Further resilient means permit movement of the safety flap in the opposite direction from its partially open position toward a closed position relative to the outlet passage. The flap is moved to the fully open position against bias of a helical torsion spring (38, Fig. 5) when a grassbox (not shown) is fitted to the rear of the mower, the flap then resting on the grassbox. For packaging purposes, the flap is moved against the further resilient means, in the form of extension arm (39) to a closed position.

Description

ROTARY LAWNMOWERS This invention relates to a rotary lawnmower in which a rotary cutter blade is disposed in a cutting chamber beneath a protective housing, and in which grass cuttings are discharged from the cutting chamber through an outlet passage.

In such a lawnmower, it is common practice to include a safety flap across the outlet passage. The flap is normally spring biased downwardly toward a closed position, and is manually pivoted upwards against the spring bias to an open position when fining a grass collection device to the outlet.

However, circumstances can arise in which the user wishes to operate the lawnmower without collecting the grass cuttings. For this reason, the flap does not completely close the outlet passage when biased to its closed position but remains partially open.

For safety reasons, the opening is sufficient to allow the passage of grass cuttings which are then deposited on the ground, but insufficient to allow the user access to the rotating blade.

A known method of creating the partial opening is to mould the safety flap with relatively deep side pieces which abut a vertical surface at the rear of the mower housing. In this manner, the safety flap is biased to a position in which it remains slightly inclined to the vertical surface at an angle of around 150 and protruding from the rear of the mower housing. This is a disadvantage for the manufacturer when packaging the mower since, to accommodate the protruding flap, the package case must be larger than would otherwise be required.

According to the present invention a rotary lawnmower which has a safety flap movable against a resilient bias from a partially open position across an outlet passage communicating with a cutting chamber to a fully open position comprises further resilient means permitting movement of the safety flap in the opposite direction from its partially open position toward a closed position.

In a preferred embodiment the flap is movable from its partially open position to its fully open position against the bias of a first spring and is also movable against the bias of a second spring toward its closed position. The first spring preferably comprises a helical torsion spring, and the second spring is preferably a lever spring.

In one particular embodiment, the two springs are formed as an integral unit from a single length of wire.

In the accompanying drawings, by way of example only: Figure 1 is a schematic view of a lawnmower including a safety flap across the exit chute of the cutting chamber; Figure 2 is a plan view of the safety flap; Figure 3 is a section on line C-C in Fig. 2; Figure 4 is a side elevation of the flap; Figure 5 is a side elevation of a spring unit for biasing the flap; and Figure 6 is a front view of the spring unit.

Referring to these drawings, a rotary lawnmower 10 includes a cutter blade 12 rotatable about a vertical axis in a cutting chamber 13 formed beneath a protective deck 11. The blade is driven by an electric motor (not shown) also enclosed beneath the deck 11. The grass cuttings from the chamber 13 are impelled by the upturned edges of the cutter blade into an air stream created by a fan 19 and ejected rearwardly through an exit chute in a well known manner.

A safety flap 36 is pivotally mounted at the rear of the mower across the exit chute.

The flap pivots on a horizontal spindle 37 located at the top rear portion of the mower housing, and includes shallow side walls 48a, 48b having aligned openings 49a, 49b for receiving the spindle 37. In normal use, the flap 36 is lifted from the partially open position shown in Fig. 1 to a fully open position against the bias of a helical torsion spring 38 located on the spindle 37, and a grassbox (not shown) is then fitted to the rear of the mower. In its fully open position the flap then rests on the lid of the grassbox, and automatically drops back to its partially open position across the exit chute when the grassbox is removed for emptying.

In practice, the user of the mower may occasionally wish to mow grass without the grassbox fitted. In this case it is important that the flap 36 should not completely block the exit chute but should remain partially open to avoid the chute clogging.

This is achieved by providing the helical torsion spring 38 with an extension arm 39 which acts as a leaf spring urging the flap outwardly to its partially open position.

The torsion spring 38 and extension spring 39 therefore act in opposing directions.

A particular advantage of this arrangement is that the flap 36 can be urged to a closed position (shown in dashed outline in Fig. 1) against the bias of the extension spring 39 when packaging the mower in a packaging case. With the handle (not shown) folded over the mower housing 11, a particularly compact rectangular package is thereby achieved.

The combined springs 38, 39 are formed from a length of cold drawn carbon steel wire, the torsion spring 38 consisting of tightly wound coils 41 on the spindle 37.

The coils are positioned on the portion of the spindle which passes through one of the wing portions 42a, 42b of the flap 36 on each side of a central recessed portion 43 providing a hand grip for lifting the rear of the mower. The short extension arm 44 is then fixed at a location within the rear of the mower housing while the long extension arm 39 has its free end located in a lug 45 formed on the inside surface of the flap 36. The extension arm 39 includes a bend 46 which abuts a projection at the rear of the mower housing so that when the flap 36 is urged toward the rear face of the mower housing, the extension arm 39 is straightened and acts as a leaf spring.

In this manner, the flap 36 is normally biased by the spring 39 to an outwardly inclined position relative to the rear face of the mower housing, but it can be urged against the bias of the spring 39 to a substantially vertical position flush with the rear face of the mower housing.

Claims (8)

1. CLAIMS 1. A rotary lawnmower comprising an outlet passage through which grass cuttings are ejected from a cutting chamber, a safety flap movable against a resilient bias from a partially open position relative to the outlet passage to a filly open position, and further resilient means permitting movement of the safety flap in the opposite direction from its partially open position toward a closed position relative to the outlet passage.
2. 2. A rotary lawnmower according to claim 1 wherein the flap is movable from its partially open position to its fully open position against the bias of a first spring, and wherein the said further resilient means comprises a second spring.
3. 3 A rotary lawnmower according to claim 2 wherein the first spring comprises a helical torsion spring.
4. 4. A rotary lawnmower according to claim 3 in which the second spring comprises a lever spring.
5. 5. A rotary lawnmower according to claim 4 wherein the two springs are formed as an integral unit from a single length of wire.
6. 6. A rotary lawnmower according to claim 4 or claim 5 wherein the safety flap is pivotally mounted on a spindle and the torsion spring comprises a helically wound coil disposed around the spindle.
7. 7. A rotary lawnmower according to claim 6 wherein a final turn of the helically wound coil is extended downwardly from the spindle to form the lever spring.
8. 8. A rotary lawnmower according to claim 7 wherein a first turn of the helically wound coil is extended downwardly from the spindle and secured to the body of the lawnmower.