AU2006200177A1 - A cutting mechanism for shredding waste - Google Patents

Description

I

Regulation 3.2 Revised 2/98

AUSTRALIA

Patents Act, 1990

ORIGINAL

COMPLETE SPECIFICATION TO BE COMPLETED BY THE APPLICANT NAME OF APPLICANT: ACTUAL INVENTOR: ADDRESS FOR SERVICE: INVENTION TITLE: DETAILS OF ASSOCIATED APPLICATION NO: MediVac Technology Pty Limited (ACN 077 391 541) Mark Henry Butler Peter Maxwell and Associates Level 6 Pitt Street SYDNEY NSW 2000 A CUTTING MECHANISM FOR SHREDDING WASTE Divisional of Australian Patent Application No. 2001 295 274 filed on October 2001 The following statement is a full description of this invention including the best method of performing it known to us:m:\docs\20011089\092174.doc This invention relates to the treatment of waste material and more particularly to a cutting mechanism for shredding waste.

For the sake of convenience, the invention will be described in relation to cutting mechanisms for waste treatment apparatus for use in the sterilisation of infectious and/or quarantined waste. However, it will be appreciated that the invention is not limited to that particular use as it will find application in treating other types of waste which may or may not require sterilisation.

According to one aspect of the invention there is provided a cutting mechanism for shredding waste comprising a rotatable planetary gearbox having a drive shaft and a plurality of planet gears and includes a stub axle projecting out of the gearbox from each planet gear and a rotating cutting head on each stub axle with the cutting heads being in close proximity to one another and wherein rotation of the drive shaft rotates the planetary gearbox in one direction and each of cutting heads in the opposite direction.

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings in which:- Fig. 1 is a front elevation of an appliance according to the teachings of the present invention; Fig. 2 is a side elevation of the device depicted in Fig. 1; Fig. 3 is a schematic side elevation, partially cross-sectioned, of the device depicted in Figs. 1 and 2; Fig. 4 is a perspective view of a shredder incorporating a planetary gearbox according to the teachings of the present invention; Fig. 5 is a perspective view of a planetary gearbox incorporating a cutter with anti-sense helical cutting edges; and Fig. 6 is a schematic view of a device utilising a common steam boiler to 16/01/06 3 supply a medical instrument steriliser and placed sterilisation unit.

As shown in Fig. 1 a combination biomedical waste processor and instrument steriliser 10 is packaged within a single housing 11. The housing 11 incorporates an instrument panel 12, a sealed upper compartment 13 which is accessed with a sliding door 14, a sealed lower compartment 15 which is accessed by a hinged door or sliding drawer 16 and a lower sliding drawer 17 which provides access to processed waste material. The control panel 12 may also incorporate a touch screen display 60. The housing 11 and working surfaces are preferably formed from stainless steel and the entire apparatus may be mounted on castors or wheels 18. The device 10 is sized for under bench top use.

In preferred embodiments the door or drawer 14 provides access to an arrangement of stacked trays 20 which are adapted to receive medical instruments for sterilisation.

The lower compartment 15 contains a biomedical waste shredder and steriliser 21. The door or drawer 16 allows contaminated waste to be introduced into a hopper 22. When the door or drawer 16 is closed, a counterweight 23 urges the contents of the hopper 22 toward a shredder 24.

The hopper 22, trays 20 and shredder area may be provided with a steam jacket 40 which is supplied either externally or from an internal boiler 30. The steam jacket may be used to preheat the contents of the hopper 22 prior to a during delivery to the shredder mechanism 24. The sterilised and shredded waste is delivered to a user accessible compartment 50 which is accessible through the drawer 17 on the front of the device The shredder 24 is driven by an electric motor 25 through a belt or chain drive 26.

16/01/06 In preferred embodiments, the steam is supplied at a pressure of 200KpA and a temperature of 1340C. A typical program comprises the administration of pressurised steam for approximately 3.5 minutes. Depending on the hopper size the device is capable of a throughput rate of approximately 10-15 litres per cycle and may operate from a standard 10 Oamp/240volt power supply. A programme logic controller 31 permits a range of user determined or pre-programmed cycles to suite the specific needs of almost any application requirement.

The device 10 may also be equipped with a vacuum pump 32 which is intended to evacuate the ambient air prior to instrument or waste steam treatment and may also be used to evacuate the device after steam treatment.

The device 10 also incorporates a high efficiency particle arrester (HEPA) 33 for the treatment of discharge gases.

Also provided is a condenser 34 and a water filter 35 for treating the gases and liquid by-products of the shredding and sterilisation process.

As shown in Fig. 4 a shredding mechanism 108 according to one embodiment of the invention comprises a planetary gearbox 110 which is driven by the motor 25. The planet gears of the gearbox 108 each drive a rotating cutter 109 mounted on a stub axle with the cutting heads 109 being in close proximity to one another. Each cutter features longitudinal cutting edges 120 and may also include optional radially disposed cutting edges 121 on the end faces of one or more of the cutters 109. In this embodiment, the rotation of the central shaft 125 of the gearbox 110 causes the cluster of cutting heads 109 to rotate in one direction 126 and the individual cutters 109 to rotate in an opposite direction 127.

16/01/06 As can be seen in Fig. 4, the gearbox 110 has a centre line along the axis of the drive shaft 125 and the stud axles are equally spaced from the centre line and equally spaced from one another.

As shown in Fig. 5, the rotating cutter 200 may incorporate helical cutting edges 201 rather than the longitudinal cutting edges 120 depicted in Fig. 4. In the example depicted at Fig. 5, the helical cutting edges 201 are provided in an anti-sense direction. Thus, waste coming in contact with the helical edges 201 on the body of cutting heads 200 are urged toward the face 202 of the cutter rather than toward the gearbox 127 when the cutter is rotated in the direction of the arrow 203.

The device 10 is also capable of providing on-line system diagnostics and real time data links to other devices. It may be optionally controlled by a personal digital assistant (PDA) and can provide log files of its operation in any number of formats.

In operation, an operator loads waste into the hopper 22 and the hatch door 16 is sealed manually or automatically. Unless this is done the system will not operate. The counter weight 23 maintains a back pressure upon the waste on door closure. Then the device is started.

A vacuum is delivered to remove all air, with the outgoing air flashed on an incoming steam line and filtered through HEPA and option ozone or UV treatments.

Thereafter, the internal boiler 30, or external steam source delivers steam to the treatment chamber via multiple steam points. In the alternative, an internal heater converts waste fluids to steam and a dynamic saturated steam environment is established. A preset temperature is maintained (134 0

C

for 3.5 minutes) within a total 7-minute cycle.

16/01/06 6 The multiple cutters 109 rotate in one direction, grabbing and tearing the product while the drive head 110 rotates in the opposite direction transporting the material around the inside of the treatment chamber. Once the required residence time has been achieved the steam is vented down to atmospheric pressure and upon reaching the pre-specified safe condition the discharge door 17 is automatically released. The cutters continue to operate for three minutes and the waste is forced against a specially designed grating 90 where the shredded material takes the path of least resistance and extruded through the holes to the discharge chamber/bags.

The hole-size in the grating 90 effectively controls the cross-section of the discharged material.

A post treatment vacuum is delivered to remove condensate and facilitate drying of the shredded waste as the cutters continue to provide a dynamic environment.

After the treatment cycle the unit can be purged with steam to sanitise the internal surfaces of the machine.

The feed and cuter units are powered by an electric transmission 25, 26 with the automated treatment sequence controlled by a PLC 31. This feature means that the unit can operate on a standard domestic power supply.

The device has a throughput rate of 10-15 litres per cycle at 1340C depending on the material involved and operates from a standard 10 Oamp/240 volt power supply. The PLC permits a range of pre-programmed alternative cycles to suit the specific needs of almost any application requirement.

The all stainless steel machine has been designed to provide optimum performance, long life, low maintenance and ease of operation.

As shown in Fig. 6, what were effectively the upper compartment 13 and lower compartment 15 may be provided as separate units 210, 211 which are 16/01/06 7 supplied by a common steam generator or boiler 212. The separate compartment 210 contains an arrangement of stacked trays 213 which are adapted to receive medical instruments for sterilisation. The other separate compartment 211 contains a biomedical waste shredder and steriliser of the type depicted in Fig. 3. Separate instrument controls 215, 216 may be provided on each of the separate compartments 210, 211. In the alternative, a common control panel 217 may be located on the steam boiler 212 so as to control both compartments 210, 211. In this way, the instrument steriliser 210 may be physically separated from the waste sterilisation unit 211.

It will be appreciated that the utilisation of the present invention will result in considerable cost savings to institutions and individuals with respect to their disposal costs. The utilisation of the invention also allows for greater control over future costs, handling costs and transport liabilities.

While the invention has been disclosed with reference to particulars details of construction these have been provided by way of example and not as limitations to the scope or spirit of the invention.

16/01/06

Claims (9)

1. A cufftting mechanism for shredding waste comprising a rotatable planetary gearbox having a drive shaft and a plurality of planet gears and includes a stub axle projecting out of the gearbox from each planet gear and a rotating cufftting head on each stub axle with the cutting heads being in close proximity to one another and wherein rotation of the drive shaft rotates the planetary gearbox in one direction and each of cufftting heads in the opposite direction.

2. A cutting mechanism according to claim 1 wherein the gearbox has a centre line and the stub axles are equally spaced from the centre line and equally spaced from one another.

3. A cutting mechanism according to either of the preceding claims wherein each cutting head has a body portion having base adjacent the gearbox and a free end face remote from the gearbox and a plurality of cutting edges spaced around the periphery of the body portion.

4. A cutting mechanism according to claim 3 wherein each cutting head has 10 cutting edges.

A cutting mechanism according to claim 3 or claim 4 wherein the cutting edges are helical cutting edges which extend from the base to the free end of each head. 16/01/06

6. A cutting mechanism according to claim 5 wherein the end of each cutting edge adjacent the gearbox leads the other end of the cutting edges adjacent the outer face of the cutting head.

7. A cutting mechanism according to any one of the preceding claims having four cutting heads.

8. A cutting mechanism according to any one of the preceding claims wherein the gearbox is driven by a hydraulic motor.

9. A cutting mechanism according to any one of the preceding claims mounted within a chamber having an inlet for receiving waste to be shredded and an outlet for discharging shredded waste. A cutting mechanism for shredding waste substantially as hereinbefore described with reference to Figs 4 and 5 of the accompanying drawings. Dated this 16 th day of January 2006 Medivac Technology Pty Limited SPatent Attorneys for the Applicant PETER MAXWELL ASSOCIATES 16/01/06