Accumulator-Powered Lawn-Mower

The invention relates to a lawnmower with an electric motor for driving the cutting implements which is fed by a rechargeable battery, having the features specified in the preamble of patent claim 1. Such a lawnmower is known from WO 95/08 256. In the case of the latter, the connection contacts between battery and chassis are designed as plug-in contacts, and these plug-in contacts simultaneously form a mechanical attachment means which are intended to attach the battery in a holder of the lawnmower chassis. In this case, the contact sockets attached to the battery cover are mounted in a floating manner, i.e. laterally displaceably, in this cover, in order that contacting can take place even if they are not placed exactly onto the pin connectors in the lawnmower chassis. The floating mounting means that mechanical attachment of the battery in the chassis is possible only to a limited extent. Furthermore, in particular if vibration occurs, reliable contact-making is not ensured, especially when one considers the high currents which flow during the operation of such a lawnmower.

The invention is therefore based on the object of improving the mounting of the battery in the chassis holder. The set object is achieved by the features specified in the characterizing part of patent claim 1. The battery is secured in the battery compartment in an interlocking manner by the lock bolts, and it cannot fall out from its holder even if the lawnmower is tilted or turned over for some reason or other. The locking means automatically engage when the handle joined to the battery housing is folded down. Similarly, automatic unlocking occurs when the handle is swung up, in order to grasp the battery by the handle and take it out in order that it can be charged elsewhere.

The electrical contact-making is completely separate from the mechanical attachment means. Since, according to claims 10 and 11, these contacting means are designed as sliding-action contacts, it is not necessary to overcome any great force when removing or inserting the battery, because the contacts are designed as sliding-action contacts. On the other hand, considerable forces have to be exerted if, as in the prior art, the plug-in contacts simultaneously effecting the mechanical attachment have to be plugged one into the other or pulled apart, because the plug-in contacts oppose the displacement with a much higher resistance.

The design of the sliding-action contacts according to the invention also effects a self-cleaning of the contact areas, with the result that reliable contact-making is always ensured.

Further developments of the invention emerge from the subclaims.

An exemplary embodiment of the invention is described below with reference to the drawing, in which:

FIG. 1 shows a diagrammatic representation of the battery, fitted in a lawnmower, with the attachment means;

FIG. 2 shows a diagrammatic representation of the battery with the contacting means;

FIG. 3 shows a perspective representation of the locking means coupled to the handle;

FIG. 4 shows a perspective, partially broken-open view of the battery compartment of a lawnmower with flexibly supported battery; and

FIG. 5 shows a partial vertical section of the battery holder and battery contacting means.

In the drawing, only the parts essential for the invention are represented, namely the battery, the battery holder and locking means as well as the contacting means, while the individual parts of the lawnmower are merely indicated. The lawnmower, which has on its chassis the compartment for fitting the battery, may be designed in various ways. It has, in a known way, an electric motor, which is fed by the battery 10 via connection leads (not shown). The battery 10 is an electrochemical secondary element, and nickel-cadmium batteries or lead-acid batteries primarily come into consideration for this. The battery is located in a housing, and the reference numeral 10 denotes the housing with the fitted battery.

The battery housing bears a handle 12, the side legs 14 of which can pivot about a spindle 16. At the part of the legs 14 lying under the pivot spindle 16, the legs of a bracket 18 are articulated about a spindle 20, which lies under the spindle 16. This bracket 18 has one or more, for example two, lock bolts 22 which, when the mower is in the state of readiness, engage in interlocking recesses 24 which are arranged in a wall 26 of a battery compartment 28, into which the battery with housing can be fitted. As can be seen in particular from FIGS. 1 and 3, the lock bolts 22 are inserted into the interlocking recesses 24 by folding down the handle 12, whereby the battery is secured in an interlocking manner in the vertical direction. After swinging the handle 12 up into the position which can be seen from FIGS. 1 and 2, the battery can be removed from the compartment and replaced into it. The battery 10 rests on the bottom of the compartment, on flexible supporting means. These may be formed of flexible material, for example foam, or have springs. According to the exemplary embodiment represented in FIG. 4, the supporting means comprise helical compression springs 30. These flexible supporting means prevent the battery from hitting the bottom of the compartment if there is battery movement. In order to ensure that the battery is always fitted correctly into the battery compartment, guide means, not shown in the drawing, are provided in the form of vertical ribs and grooves. A corresponding corner design of the battery housing and battery compartment is also conceivable.

The support means prestress the battery or its housing against the locking means, with the result that the battery remains securely fixed during operation.

For contacting, the battery or its housing bears in a side wall a plurality of contact lugs 32, which are provided running parallel to one another in the vertical direction. Arranged in the battery compartment is a corresponding number of contact springs 34. These contact springs 34, designed as leaf springs, are restrained at their upper end and bear under prestress against the contact lugs 32 of the fitted battery. This prestressing is increased by compression springs 36, which act on the contact springs and ensure reliable contact-making even with the high currents flowing during operation.

As can be seen, the contacting means 32, 34, 36 are separate from the mechanical locking means 18, 22, 24. The design as sliding-action contacts ensures a self-cleaning of the contacts every time the battery is fitted and removed. Even if a movement between the battery or battery housing and battery compartment takes place during operation for some reason or other, the current transfer is not disturbed as a result, because if anything the contacts 32 and 34 slide on one another.

As can be seen from FIG. 5, the supporting springs 30 may act on a carrier plate 38, which forms the bottom of the battery compartment and supports the battery or its housing.

According to the exemplary embodiment represented, the battery compartment is provided in vertical arrangement in the lawnmower chassis. It is also conceivable, however, to design the compartment horizontally, the supporting means, the locking means and the contacting means having to be designed in a corresponding way, to provide lateral insertion with sliding-action contact connection and lateral locking.

10 Battery (housing)

12 Handle

14 Side legs

16 Spindle

18 Bracket

20 Spindle

22 Lock bolts

24 Interlocking recesses

26 Wall

28 Battery compartment

30 Helical compression springs

32 Contact lugs

34 Contact springs

36 Helical compression springs

38 Carrier plate