The present invention concerns lid assemblies for devices such a macerators which are used to macerate waste products, for example disposable pulp products (for example bed pans, urinals etc.) and incontinence pads, in a hospital or other health care environment.

In this regard, macerators include a lid that the nursing staff need to access in order to deposit pulp products for disposal. This lid is closed to enable maceration to take place.

Currently macerators have spring/damper arrangements, high pressure gas struts or actuated/motorised opening arrangements. They are located in the frame of the machine dictating that the machine is larger than is necessarily required .

Access to maintain these arrangements is problematic as they are provided internally within the machine at the rear. Actuated/motorised arrangements are moreover potentially unreliable and require additional safety processes, for example to sense when a foreign object obstructs its operation. They are also damaged by incorrect operation by a person forcing the mechanism to open or close at a faster rate than at which it is travelling .

The present invention is directed to alleviating the problems associated with such known arrangements.

According to the present invention there is provided a lid assembly for a macerator, the lid assembly comprising :- one or more lid hinge mountings for pivotally mounting said lid assembly to a macerator frame; and spring means integrated into said lid assembly for counterbalancing the weight of the lid assembly. In this way, a compact and reliable lid assembly can be achieved.

Preferably, the spring means comprises a pair of springs extending substantially away from said one or more hinge mountings along opposite sides of said lid assembly. The position of the spring means along the sides of the lid assembly optimises the use of space within the lid assembly.

Conveniently, the one or more springs have tension adjustment means for allowing adjustment of the tension in the one or more springs in situ within the lid assembly. This allows for the force required to open and close the lid assembly to be tailored to specific design requirements.

The one or more hinge mountings may each comprises a plate for fixedly mounting the one or more hinge mountings to the macerator frame, and an arm member pivotally mounted to said plate, the one or more spring means having one end coupled to said plate, and the other end coupled to a distal end of the arm.

Preferably, the lid assembly further comprises a support frame, having a pair of said arm members connected by one or more cross support limbs which are coupled to one or more support rails. In this manner, the components of the lid assembly can be built around the frame.

Conveniently, the support rails are mounted to a lid moulding assembly.

Each hinge mounting can includes a pivot axis about which its arm member is mounted, the associated spring means being anchored to a point below the pivot axis. As such, a mechanical advantage is created which thereby effectively balances the weight of the lid assembly allowing it to be opened and closed with minimal force. Preferably, each arm member comprises a channel section, within which the associated spring means is housed . This assists with optimising the compactness and strength of the assembly.

Conveniently, the channel section has apertures allowing access to the spring means. These can be for general maintenance or tension adjustment of the spring means.

Preferably, each arm member is mounted to pivot on a pivot member that extends outwardly from its associated hinge mounting . The compactness of the lid assembly can as such be maintained in this way.

The hinge mountings may be provided inwardly of the arm members within the lid assembly.

It will be appreciated that other opening devices may be provided in place of, or in addition to the spring means, for example high pressure gas struts or actuated/motorised opening arrangements.

The present invention also encompasses a macerator incorporating a lid assembly as defined above.

An embodiment of the present invention will now be described by way of example and with reference to the accompanying drawings, of which:-

Figure 1 shows a front and side perspective view of an upper section of a macerator having a lid assembly of the present invention;

Figure 2 shows a rear and side perspective view of the lid assembly of Figure 1 ; Figure 3 shows a detailed perspective view from above of the lid assembly of Figures 1 and 2; and

Figure 4 shows a detailed cross-sectional view of a spring used in the lid assembly of Figures 1 to 3.

As shown in Figures 1 to 4, a macerator 1 includes a lid assembly 2 (shown stripped of its outer top mounding) .

A pair of cartridge springs 3 are mounted in the lid assembly of the macerator. More specifically, the springs are mounted within arm members 4 between anchor pins 5 and 6, anchor pins 5 extending outwardly from hinge plates 20 of hinge mounting 21 and anchor pins 6 being provided at a distal end of the channel 7 making up the respective arm members 4. The pins 5 are positioned below and thereby spaced from the main pivot axis 8 of the arm members such that a mechanical advantage is created when the arm members are pivotally displaced relative to the hinge mountings.

This mechanical advantage is harnessed to counterbalance the weight of the lid assembly when it is opened and closed. The position of the pivot fulcrum is such that the lid assembly closes under very little force, typically 1 kg.

The arm members 4 are arranged to extend up the sides of the lid assembly and are mounted outwardly of the hinge mountings. In this way they occupy minimal space so that the whole lid assembly is kept compact.

The arm members attach to a frame, including cross limbs 1 0 and support rails 1 1 to which the lid mounding assembly 1 2 is attached. The arm members 4 have apertures 1 3 and 1 4 which allow access for maintenance purposes and for adjusting tension of the spring means 3. In this connection and as shown in Figure 4 the spring means 3 takes the form of a compression spring 1 6 mounted into a cartridge consisting of a bushed rod 1 7 inside a piston 1 8 having an adjustment collar 1 5 by which the tension can be adjusted.