GB2505713A

GB2505713A - Lawn maintenance apparatus

Info

Publication number: GB2505713A
Application number: GB201216164A
Authority: GB
Inventors: Ian Zetterstrom Smith; Richard D Sparkes; Roger Thomas
Original assignee: Husqvarna UK Ltd
Current assignee: Husqvarna UK Ltd
Priority date: 2012-09-11
Filing date: 2012-09-11
Publication date: 2014-03-12
Anticipated expiration: 2032-09-11
Also published as: CN103650760B; DE102013014692A1; GB201216164D0; GB2505713B; CN103650760A

Abstract

A lawn maintenance apparatus, such as a lawnmower, comprises a housing 1 defining a cutting chamber 3 open on a bottom surface of the lawn maintenance apparatus, a plurality of wheels 2, and a cutting element 4 mounted in the cutting chamber for rotation about an axis, in which the housing further defines an impeller chamber 7, separated from the cutting chamber by at least one wall 8, and an intake passage 13 leading from the cutting chamber towards the impeller chamber, the lawn maintenance apparatus further comprising an impeller 6 in the impeller chamber mounted for rotation about the axis, rotation of the impeller about the axis causing air to be drawn into the impeller chamber through the intake passage. The apparatus may also comprise a grass collection device having a grass collection chamber 10 interposed between the intake passage and the impeller chamber.

Description

LAWN MAINTENANCE APPARATUS

This invention relates to lawn maintenance apparatus, such as, non-exclusively, wheeled lawnmowcrs.

Wheeled Iawnmowers are well known, and typically comprise a housing open on a bottom surface thereot with a rotating blade in a cutting chamber on the bottom surface. Wheels support the housing off the ground, so that the rotating blade is at a convenient height to cut grass over which the lawnmower passes. Other lawn maintenance apparatus are known, where the blade is replaced by a different cutting clement, such as scarifying elements in the case of a lawn scarifier.

It is known in the prior art to collect grass cut by the lawn maintenance apparatus.

This can be done by providing suction through an inlet rearwards of the cutting chamber (see, for example, the European patent application published as EP 0 457 433, used in a hover mower). Alternatively, the grass can be thrown by a blade having a curved wing, which imparts movement to the grass and the air around it, as disclosed, again with reference to hovcr rathcr than wheeled mowers, in the United Kingdom patent application published as GB 2 279 858.

However, the former apparatus, the grass is deposited on the ground before being picked up, which is inefficient, as some of the cut grass is likely to adhere to the remaining lawn, particularly if the ground is slightly damp. In the latter apparatus, thc grass will be thrown generally tangentially out of the cutting chamber, and so is likely to hit the walls of the cutting chamber and adhere to the walls, rather than be collected in the appropriate receptacle.

According to a first aspect of the invention, there is provided a lawn maintenance apparatus, comprising a housing defining a cutting chamber open on a bottom surface of the lawn maintenance apparatus, a plurality of wheels arranged to support the housing above a surface to be mowed, and a cutting element mounted in the cutting chamber for rotation about an axis, in which the housing further defines an impeller chamber, separated from the cutting chamber by at least one wall, and an intake passage leading from the cutting chamber towards the impeller chamber, the lawn maintenance apparatus further comprising an impeller in the impeller chamber mounted for rotation about the axis, rotation of the impeller about the axis causing air to be drawn into the grass collection chamber through the intake passage.

By having the impeller coaxially mounted with the cutting element, the drive mechanism by means of which the impeller and the cutting element are driven can be simplified; typically, a single belt drive or similar arrangement can drive both members. Furthermore, by sucking air into the impeller chamber through an intake passage cut grass can be drawn through the inlet passage. Defining a wall betwccn the impeller and the cutting element ensures that the movement of air from the cutting chamber into the impeller chamber is controlled through the passage.

The impeller and the cutting element may be arranged to rotate at the same speed.

The apparatus may comprise a common shaft on the axis on which are mounted the impeller and the cutting element. Typically, the apparatus will comprise a motor arranged to drive the impeller and the cutting clement for rotation; as such, the apparatus may comprise a drive train arranged to transfer rotational motion of an output shaft of the motor to the common shaft so as to rotate both the impeller and the cutting element.

Preferably, the lawn maintenance apparatus comprises a grass collection device. The grass collection device may be within the impeller chamber, but would typically comprise a grass collection chamber interposed between the intake passage and the impeller chamber. Typically, the grass collection device will comprise a perforated basket, through which air can flow but which impedes or blocks the passage of cut grass. Typically, thc basket will have perforations with a minimum diameter of at most 5 to 10 mm. The basket will preferably be perforated in a region adjacent to the impeller, the region including a portion of the basket on and around the axis.

Typically, the region will be on a bottom surface of the basket, that is the surface closest to the cutting chamber. This arrangement allows for the air to be exhausted from the basket through the bottom of the basket, which has been found to increase the amount of grass that can be removed from the air flow. The basket may, in addition, have perforated side walls, such that air can continue to flow through the perforated side walls after the bottom surface has been covered in cut grass.

The passage may be positioned so as to suck cut grass off the cutting clement. Thus, rather than relying upon the blade throwing the grass off (a large portion then impacting against the wall of the cutting chamber), the cut grass can be lifted off the cutting element, typically being entrained in the flow of air along the passage. This means that more grass will be collected in the grass collection device rather than impacting on other areas of the housing.

In order to aid grass collection, there may be a straight path from the cutting element through the passage and into the impeller chamber, particularly into the grass collection device or the basket. If corners are avoided, then grass is less likely to collect on external curves in the path.

The impeller chamber may be provided with an exhaust outlet, whereby air can pass out of the impeller chamber, the impeller being interposed between the intake passage and the exhaust outlet, such that air sucked in from the intake passage flows over the impeller before being exhausted through the exhaust outlet. Typically, the exhaust outlet will have a distal end distal from the impeller where the exhaust outlet exits the housing; in such a case, the distal end will preferably point downwards. Typically, the lawnmower will have a forwards direction, being the direction in which the lawnmower is preferably propelled by a user; the distal end will typically then be rearwards of the cutting chamber. The lawn maintenance apparatus will typically have a handle which extends rearwardly of the housing in use.

The cutting element will typically comprise a rotating blade having a leading cutting edge. In such a case, the apparatus can be a lawnmower. The blade may be flat or substantially flat, so that the blade does not substantially contribute to airflow within the cutting chamber. This means that less cut grass will be thrown off the blade, and will instead flow with the air passing through the passage, leading to less grass being impacted on surfaces within the housing.

The wheels may be provided both forwards and rearwards of the cutting chamber. As such, the apparatus may be supported off the ground by the wheels, rather than by any hover force generated by the apparatus. As such, the apparatus will typically not be a hover mower.

Alternatively, the cutting element may comprise at least one scarification clement, arranged to scarify the lawn. Each scarification clement may comprise a scarification blade or spring tine. As such, the lawn maintenance apparatus may be a lawn scarifier.

There now follows, by way of example, description of an embodiment of the invention, described with reference the accompanying drawings, in which: Figure 1 shows a partially cut away perspective view of a lawnrnower in accordance with an embodiment of the invention; Figure 2 shows a further cut away perspective view of the lawnmower of Figure 1, cut away on a vertical plane along the niidline of the lawnmower; Figure 3 shows a vertical cross-section of the lawnmower of Figure 1, through the plane of Figure 2; and Figure 4 shows an underside view of the lawnmowcr of Figure 1.

A lawnmower in accordance with an enibodinient of the invention is shown in the accompanying drawings. This lawnmower comprises a housing 1 supported by four wheels 2. The wheels 2 support the housing I above the surface to be mowed, and allow the housing I to be driven over the surface. A handle 18 is provided projecting behind the lawnmower so that a user can push the lawnmower forwards (to the left in Figure 3 of the accompanying drawings) over the surface to be mowed.

The housing defines a cutting chamber 3 open on the bottom surface of the housing 1.

A bladc 4 is provided in this chamber, mounted on shaft 9 for rotation about a vertical axis 5. Rotation of the blade 4 cuts grass over which the lawnmower is passed.

In order to collect the cut grass, a grass collection system is provided. An impeller 6 is provided in an impeller chamber 7, immediately above the cutting chamber 3, but separated from the cutting chamber 3 by a wall 8. The impeller is mounted on the shaft 9 for rotation with the blade 4 about the same vertical axis 5.

Immediately above the impeller chamber there is provided a grass collection chamber 10. This is in communication with the impeller chamber 7 through vent 11 adjacent to the impeller. The grass collection chamber 10 contains a grass collection box 12, which is of the form of an open-topped (and so five-sided) box. The walls of the box are perforated, so that air, but not cut grass, can pass through the walls. The grass collection box 12 is removable, so that it can be emptied once full.

The grass collection chamber 10 is in communication with the cutting chamber 3 through an inlet passage 13, which terminates in the grass collection box 12. Thus, rotation of the impeller 6 will tend to draw air from the grass collection chamber 10 through the walls of the grass collection box 12 and vent 11, that air itself having been drawn up the inlet passage 13. If this occurs whilst grass is being cut, the cut grass will be entrained with the moving air, the grass then depositing itself on the walls of the grass collection box 12 as it cannot pass through the perforations in the walls.

It is to be noted that the perforations extend over the majority of the walls of the grass collection box 12, including the bottom surface 17 where it is positioned over the impeller 6, thus increasing the amount of grass that can be removed from the air flow, as gravity will assist the grass in moving downwards towards the bottom surface 17.

The impeller chamber 7 is provided with an exhaust 14 which vents the air drawn from the grass collection chamber 10. The exhaust 14 exits the housing 1 on the bottom surface, behind the cutting chamber 3 in the direction of normal travel.

Having the exhaust 14 behind the cutting chamber rather than in front is advantageous, as it means that, as the mower is moved forwards, thc grass that is entering the cutting chamber will not be flattened by the exhaust 14.

As such, there is a path for air from thc cutting chamber 3, through the inlet passage 13, into the grass collection box 12, through the walls of the grass collection box into the wider grass collection chamber, through the vent 11 into the inipeller chamber 7, past the impeller 6 and out of the exhaust 14. The wall S separates the cutting chamber 3 from the impeller chamber 7 and will maintain the pressure differential that will exist between the two chambers given that the cutting chamber 3 will be slightly depressurised with respect to the impeller chamber 7.

There is a straight path 15 from thc cutting chamber 3 to the grass collection box 12; this is advantageous, as it means that cut grass entrained in the flow of air does not have to be diverted around any corners, and so is less likely to be deposited on the walls of the inlet passage. Furthermore, because it is the flow of air that directs the entrained cut grass, the grass is likely to flow with the air, and so small deviations in course can be achieved without the grass being deposited on the sides of the path; if the grass is collected by throwing, then any curves in the collection path are likely to lead to grass deposits on the outsides of those curves.

The blade 4 can be provided with a wing 16 at each end, on the trailing (non-cutting) cdges. The wings 16 impart extra motion to the air flow in the cutting chamber 3 and assist the impeller 6 in moving air out of the cutting chamber 3.

Because the impeller 3 and the blade 4 are mounted on the same shaft 9, they will rotate together. This mean that, rather than having to provide two drive stages to drive the impeller and the blade at different speeds separately, a single drive train 20 can be provided that transmits rotation from a motor 19 to the shaft 9. Typically a single belt drive can be provided, rather than a double belt as would be required if the motor and the impeller were mounted on separate shafts. Thus, the drive system can be made smaller and cheaper than otherwise would be the case.

Furthermore, because the grass is sucked into the grass collection box 12, should the grass collection box become full, any grass that starts collecting in the intake passagc 13 will be cleared by the flow of air once the grass collection box 12 is cmptied. In a prior art system where grass is simply thrown or blown into the collection box, there is no suction or other force to clear such a blockage in the intake passage 13 without user intervention.

Claims

CLAIMS1. A lawn maintenance apparatus, comprising a housing defining a cutting chamber open on a bottom surface of the lawn maintenance apparatus, a plurality of wheels arranged to support the housing above a surfacc to be mowed, and a cutting element mounted in the cutting chamber for rotation about an axis, in which the housing fur her defines an impeller chamber, scparatcd from the cutting chamber by at least one wall, and an intake passage leading from the cutting chamber towards the impeller chamber, the lawn maintenance apparatus further comprising an impeller in the impeller chamber mounted for rotation about the axis, rotation of the impeller about the axis causing air to be drawn into the impeller chamber through the intake passage.
2. The apparatus of claim 1, in which the impeller and the cutting element are mounted on a common shaft.
3. The apparatus of claim 1 or claim 2, comprising a grass collection device comprising a grass collection chamber interposed between the intake passage and the impeller chamber.
4. The apparatus of claim 3, in which the grass collection device comprises a perforated basket, through which air can flow but which impedes or blocks the passage of cut grass.
5. The apparatus of claim 4, in which the basket is perforated in a region adjacent to the impeller, the region being on a bottom surface of the basket
6. The apparatus of any of claims 3 to 5, in which there is a straight path from the cutting element through the passage and into the grass collection chamber.
7. The apparatus of any preceding claim, in which the passage is positioned so as to suck cut grass off the cutting element.
8. The apparatus of any preceding claim, in which the impeller chamber is provided with an exhaust outlet, whereby air can pass out of the impeller chamber, theSexhaust outlet being positioned on the opposite side of the impeller from the intake passage, such that air sucked in from the intake passage flows over the impeller before being exhausted through the exhaust outlet.
9. The apparatus of claim 8, in which the exhaust outlet has a distal end distal from the impeller where the exhaust outlet exits the housing; in such a case, the distal end will preferably point downwards.
10. The apparatus of claim 9, in which the apparatus has a forwards direction, being the direction in which the lawninower is preferably propelled by a user; the distal end being rearwards of the cutting chamber.
11. The apparatus of claim 10, having a handle which extends rearwardly of the housing in use.
12. The apparatus of ally preceding claim, in which the cutting element comprises a rotating blade having a leading cutting edge, the blade being flat.
13. The apparatus of any of claims 1 to 11, in which the cutting clement comprises a rotating blade having a leading cutting edge, the blade being provided with at least one wing on its trailing edge.
14. The apparatus of any preceding claim, in which the cutting element comprises at least one scarification element, arranged to scarify the lawn.