Technical Field The present invention relates to a waste disposal unit. Background

It is known to dispose of waste from beverage / coffee machines, in particular vending machines, using several methods. These methods include manual disposal of solid or particulate waste (especially used coffee grounds) and liquid waste by a pump system, both by separate means. Both methods each have their own problems in such handling waste, and in particular can cause handling and environmental hazards which can be difficult to control.

It is known for solid/particulate waste to be channelled into a tray positioned under the (grounds) waste ejection point, which is required to be manually monitored and emptied periodically during operation of vending machine. We have devised an improved waste disposal unit which seeks to overcome the shortcomings of the known waste disposal systems, and in particular, although not exclusively, coffee vending machines.

Summary

According to a first aspect of the invention there is provided a waste disposal unit which comprises a vessel which has an internal containment space to receive waste material which narrows towards a basal outlet, an agitator impeller located in the internal space arranged to mix contents in the vessel, an outlet conduit connected to the basal outlet which is provided with a pump to drive mixed material away, and a material level sensor to determine the level of material in the internal containment space, and to cause operation of the unit to be controlled thereby.

The vessel may be of bowled or funnel configuration. The inner surface of the vessel may be inclined. The pump may comprise an impeller which is driven from a common shaft to the agitator impeller

The agitator impeller may be located proximal to the basal outlet

The agitator impeller may be located within the lowermost twenty-five percent of the height dimension of the internal containment space.

The pump impeller may be located immediately below the basal outlet

The basal outlet may be located at the base of the vessel

At the junction with the basal outlet, the outlet conduit may extend generally downwardly of the outlet.

By the internal containment space narrowing we include the cross-sectional area of the space reducing in the direction of the height of the vessel.

The unit may comprise a liquid outlet directed into the internal containment space. The liquid outlet may be located towards an upper part of the containment space. The liquid outlet may comprise one or spray heads or nozzles.

The contents level sensor, which is operative to determine the level of material in the containment space, is preferably such that when a pre-determined level is reached, the unit is caused to operate.

On sensing of the pre-determined level, the unit may be arranged to cause liquid to be introduced into the vessel for mixing with the material. The contents level sensor may be arranged to halt operation of the agitator impeller when the sensed level of material is less than a predetermined level.

The unit may comprise a flushing arrangement comprising a water inlet into the vessel and a controller, the controller arranged to cause liquid to enter the vessel at predetermined timed intervals. The unit may be arranged to be slidably inserted into and out of an in-use position. The unit may comprise external wall surfaces configured to allow the unit to be slidable. The unit may be viewed as a removable module/cassette. Underside and outwardly side-facing side walls may be configured to allow the unit to be slidable.

The waste disposal unit may comprise one or more features in the detailed description and/or as shown in the drawings.

Brief description of the drawings

Various embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which:

Figure 1 is a schematic cross-section of a waste disposal unit,

Figure 2 is a schematic cross-section of a waste disposal unit according to an alternative embodiment,

Figure 3 is a perspective view of a second embodiment of the invention,

Figure 4 is a schematic view of an agitation blade, and

Figure 5 is an end view of the embodiment of Figure 3 in situ on a support structure.

Detailed Description

There will now be described a waste disposal unit in which waste material is introduced into a containment vessel, and a material level sensor determines the operational state of the unit, as described with reference to Figures 1 and 2. Liquid is arranged to be introduced into the vessel, and an agitation impeller causes the (particulate or solid/liquid) matter therein to be fluidised. A pump impeller causes the fluidised material to be pumped away via a basal outlet in the vessel. With reference initially to Figure 1 , there is shown a waste disposal unit 1. The unit 1 comprises a containment vessel 2. The inner surface of the vessel 2 is of substantially bowl shape and, in particular in that towards the lowermost portion 2a of the vessel, the vessel narrows towards a discharge outlet 3. In use, this causes a funnel effect to assist movement of waste material towards the discharge outlet.

The discharge outlet 3 is located at the base of the vessel. At the uppermost part of the vessel, there is provided an inlet 7 for entry of the waste into the vessel 2. There is also provided a water inlet 8, arranged to be connected to a water supply and introduce water into the vessel. The inlet 8 comprises a conduit 8a which at least in part encircles the inner surface of the vessel, at the upper region of the vessel. The conduit 8a is provided with multiple apertures to allow water in the conduit to enter into the vessel 3. Control of water into the conduit 8a is controlled by a valve 8b. In addition to use of the conduit 8a to introduce water into the particulate/solid waste, to fluidise the same, the conduit 8a may also be used to introduce water to flush the vessel. This may be effected periodically, for example by way of a timer-operated valve. The conduit 8a may comprise an integrated Venturi port to allow introduction of metered sanitizer/ chemical dispersant. The unit further comprises a level sensor module 10. The sensor module comprises two probes 10a and 10b, each of a respective different length and each provided at its free end with an electrically conductive portion. When the level of material in the vessel covers the conductive portions of each probe a circuit is completed, which is then indicative of a condition in which the waste disposal unit is caused to become operational, as will be described in more detail below. The probes extend from an upper region of the vessel into the internal volume of the vessel.

The unit further comprises a motor 12, which is mounted atop the vessel. The motor 12 may be an electrically cantilevered pump, resiliently mounted to provide noise reduction. The motor comprises a drive shaft 12a which extends into the internal vessel space. Secured fast to the drive shaft 12a there is provide an agitator impeller 14 and a pump impeller 15. The agitator impeller 14 is located in a lowermost region of the internal volume of the vessel, and in particular is proximal and adjacent to the discharge outlet 3. Relative to the height of the vessel, the agitator impeller is within the lowermost twenty five percent of the internal volume. Convenient the agitator impeller and the pump impeller are driven from a common shaft, allowing both mixing and pump operations to be effected using a single motor.

The pump impeller 15 is located directly under the discharge outlet 3, and within a discharge conduit 20. In operation the pump impeller 15 when caused to rotate by the drive shaft 12a forces fluidised particulate exiting the discharge outlet, along the discharge conduit 20, and towards a drainage system. (By fluidisation , we include the meaning of increasing the ratio of liquid to solid matter within the containment vessel.) The discharge conduit 20 is provided with a non-return or check valve or a double non-return valve 20a to prevent backflow towards the discharge outlet 3.

The pump impeller 15 may be centrifugal design, comprising straight and/or curved blade surfaces. The agitator impeller 14 is principally selected/designed to mix particulate matter with the introduced liquid, and additionally may be arranged to be capable of breaking up particulate matter, and ensure that particulate matter is suspended within the liquid. An example of such an agitator impeller is shown in Figure 4 which comprises two upwardly directed, and diametrically opposed blades, 14a. The upper part of the vessel 2 is provided with a cover 22, which encloses the containment space of the vessel. This primarily serves to reduce odours from waste material emanating from within the vessel. However, in order to prevent excessive pressure build-up within the containment space, a breather port is provided (not illustrated) which includes carbon activated filters. This allows gas to escape, from within the volume, and at the same time reduce undesirable odours.

The inlet 7 provides a conduit comprising a chute or vertical channel for entry into the internal space of the vessel of the waste material. The inlet 8 is aligned with the ejection point of waste material e.g. used coffee grounds from a coffee vending machine. The particulate/solid waste material fall under gravity into the vessel, and then to be dispersed in solution by the agitator impeller. The inlet 7 may also be arranged to be in communication with a drip tray, and wherein liquids collected in the drip tray are fed under gravity into the vessel via the inlet 7. A flushing arrangement may be provided to periodically flush the inlet 8 with sanitizers and/or chemical dispersants. The waste disposal unit comprises a controller comprising a data processor, which may include a PLA (programmable logic array) and/or software enabled device. The controller receives input signals from the level sensor and has an output line to an actuator valve for the conduit 8a and for the pump motor 12. Accordingly, in response to the sensed level of material in the vessel, the motor and the introduction of water into the vessel can be controlled. Advantageously, this provides a fully automated waste disposal system requiring no or very little manual intervention. In one embodiment of the invention, the unit is connected to a coffee vending machine, and in particular may be convenient slidably inserted into a space below the vending machine (as is described in more detail below). In an alternative embodiment, the unit may be integral with the vending machine.

In use, waste particulate material is received, through the inlet 7, into the vessel containment space. With further quantities of waste entering the vessel, the level of the waste material therein gradually increases. When the level of the waste material is sufficient such that it covers the electric contacts of both probes 10a and 10b, a circuit is completed. This causes a signal to be sent to the controller. On receipt of the signal, the controller outputs a signal which causes activation of the motor 12 and activation of a valve controlling the flow of water into the conduit 8a. The introduction of water from the conduit reaches the contained waste material, and the rotation of the agitator impeller causes the particulate waste material to be dispersed and fluidised in the water. Rotation of the pump impeller 15 urges fluidised material along the discharge conduit 20. When the sensed level falls below the predetermined level, the controller receives a signal indicative of the same, and causes the activation of the motor to halt. It will be appreciated that the control of the fluidizing water into the vessel by outlet conduit 8a may be timed so that a pre-set quantity of water is introduced into the vessel.

An alternative embodiment of a waste disposal unit is shown in Figure 2. Like reference numerals are used to denote the same or similar components. In this embodiment, the motor 12 is located at an underside of the unit.

With reference to Figure 5 there is shown a perspective view of an embodiment 100 of a waste disposal unit. The unit 100 is essentially functionally identical to those shown in Figures 1 and 2, albeit there are some structural differences. For ease of reference, the same or substantially the same, features are referred to using like reference numerals. As will be explained below, the unit is essentially of a modular nature, which is dimensionally configured to allow the unit to be conveniently pushed into and pulled out of position, in slidable fashion.

The unit 100 comprises a casing or housing 101 which comprises an uppermost surface 101a, and two flanking side walls 101b, provided aligned with the longitudinal extent of the unit. The uppermost surface 101a is provided with a plurality of cut-outs or apertures arranged to receive an inlet chute 107, and a drive shaft of the motor 12. Further, apertures 108 and 1 10 are provided for receipt of inlets for water (for fluidisation and/or flushing), and an aperture for insertion of a level sensor device.

A containment vessel 2 is fixedly attached to the housing 101 , and is of dished internal shape, towards a discharge outlet (not illustrated).

In use, the side walls 101b (and underlying surfaces thereof) are arranged to be slid into position on a surface of a suitable support structure, 200, which comprises a support surface 202, and two spaced-apart walls 201. The spacing of the walls 201 is arranged to receive the width of the unit, and thereby provide a lateral locating function. The support structure may also comprise a stop feature which is rearwardly disposed which serves to limit the extent of rearward sliding movement, and thereby ensure that when in the 'home' position, that the chute is correctly aligned the outlet of the coffee vending machine. The support structure thus provides a guide channel into which the unit can be positioned and located. The support structure may be a shelf of a worktop or work surface, which overall structure supports a coffee machine. The support structure may be a cabinet, provided with rails to support the waste disposal unit 100. When in position, the waste disposal unit 100 underlies the coffee vending machine, and in particular, the chute 107 is aligned with a waste material outlet of the machine. For example, the chute of the unit may be arranged to be aligned with an outlet of a drip tray or the like of a coffee vending machine. Generally, the waste disposal unit resides underneath a coffee vending machine, and is arranged to receive waste material from the machine, under the force of gravity. The chute 107 may advantageously be arranged to be removably attachable to the uppermost surface 101a. When detached, conveniently allowing access for visual inspection of the agitator impeller. Although mention is made to coffee vending machines, it will be appreciate that the waste disposal unit will find utility in other areas and applications. As an alternative to the level sensor comprising electrical resistance probes, level sensing may be effected by infrared or reed switches, pressure, or other means. Further, the unit may comprise a level sensor to halt operation of the coffee vending machine in case of risk of flooding from the containment vessel. The unit may be provided with electrical connectors and/or fluid ports which are arranged to automatically connect with suitable counterpart connectors/ports, and so avoid the need for an operator to make those connections manually.

It will be appreciated that all electrical devices and components meet required national/international standards of electrical integrity.