Field of the invention

[0001 ] This invention relates to apparatus for cleaning components, for example automotive or other types of machinery components, and in particular to such an apparatus that use a biological component as a cleaning agent. Background of the invention

[0002] Parts washing apparatus - known more simply as parts washers - are known in particular for use in cleaning components or parts (for example automotive parts) that may be covered in oils, grease, various hydrocarbons and other organic components. Detergents and other cleaning agents may be used and a variety of parts washers are known which are designed to facilitate the cleaning of such parts in either an automated, semi-automated or manual manner.

[0003] One known type of parts washer takes the form of a sink, basin or bath located at a convenient height for a user. Beneath the sink, basin or bath is located a tank holding a cleaning agent which may be pumped into the sink and then may drain back into the tank after use. Various filters may be provided to remove waste products from the cleaning agent before and/or after use. A brush may be provided to help a user remove oils and other unwanted matter from the parts.

[0004] In the past the cleaning agent has often been a chemical cleaning agent such as a solvent (such as kerosines, naphthas and other mineral spirits).] While such solvents are effective there is a wish to move away from the use of chemical solvents for environmental reasons as they can be difficult to dispose of. There may also be health and other hazards in using chemical cleaning agents that require their careful use and disposal. It is therefore also known as an alternative to the use of chemical cleaning agents to use a cleaning agent having a biological component. An example of such a biological cleaning agent is an aqueous solution containing micro-organisms such as bacteria that digest the waste products. An example of the use of a microbiological cleaning agent is disclosed in US 2009/0293922 A1 . Typically these cleaning agents contain a range of surfactants and mild alkalis to degrease the components to be cleaned and have a culture of appropriate bacteria to digest the oil cleaned from the components. [0005] However, one issue with the use of biological or microbiological cleaning agents is that the biological or microbiological component, eg the bacteria, must be kept alive. Often, for example, there may be an air bubbler mechanism that provides oxygen to the bacteria (for example). One factor in maintaining the bacteria (for example) alive is maintaining them at an optimum temperature. A typical optimum temperature range may be from 32°C to 50°C but more generally 35°C to 45°C. In US 2009/0293922 A1 this is done by using a thermostatically controlled heating element that extends into the tank holding an aqueous solution of the bacterial cleaning agent. The problem with this approach, however, is that is can result in hot-spots and localised heating. This can have a number of problems ranging from inadequately heated areas where the bacteria may not survive, to other areas where the temperature is too high and the bacteria may be pasteurised such that they become ineffective.

[0006] Another disadvantage of conventional biological parts washers is that they are often formed of substantial amounts of plastics material. While plastics may be a convenient material in many applications, in this context it has been found to be far from ideal and plastics often adsorp toxic materials which means that they may be hazardous to users. Summary of the invention

[0007] According to the present invention there is provided apparatus for cleaning components, comprising: a tank for holding a cleaning fluid, a sink in which components are to be washed, and pump means for pumping cleaning fluid from the tank to the sink, wherein the apparatus further comprises a generally planar heating element applied against a surface of said tank, and control means for controlling the operation of the heating element whereby cleaning fluid in said tank may be maintained at a desired temperature. [0008] Preferably the heating element is applied against an underside of the tank. Preferably a heat transfer element is applied between the heating element and the tank. [0009] The sink and/or the tank is/are preferably formed of a metal such as, for example, stainless steel.

[001 0] The tank is preferably a double-skinned tank. For example the tank may be formed of an inner tank located within an outer tank, wherein the heating element is applied against a surface of the inner tank, and wherein a thermal insulating material is provided between said inner and outer tanks. The inner tank in such an embodiment is preferably made of metal such as stainless steel.

[001 1 ] Preferably the apparatus further comprises means for preventing evaporation of cleaning fluid from said tank. For example, in one embodiment the sink includes a drain for permitting cleaning fluid to return from the basin to the tank, and the means for preventing evaporation comprises a counter-balanced closure for the drain that is opened by the weight of fluid in the sink when the basin is in use, and which closes the drain to prevent evaporation when the sink is not in use.

Brief description of the drawings

[001 2] Some embodiments of the invention will now be described with reference to the accompanying drawings, in which :- [001 3] Figure 1 is a perspective view of a parts washer according to an embodiment of the invention,

[001 4] Figure 2 is a side view of the parts washer of Figure 1 ,

[001 5] Figure 3 is a perspective view of an outer tank and base of a parts washer of the embodiment of Figure 1 ,

[0016] Figure 4(a)-(c) are side views (Figures 4(a)-(b) of the sink of the parts washer of Figure 1 and a detail (Figure 4(c)) of an anti-evaporation device,

[001 7] Figure 5 is a perspective view of an inner tank of a parts washer of the embodiment of Figure 1 , and

[001 8] Figure 6 is a top view of the inner tank of Figure 5. Detailed description of preferred embodiments

[001 9] Referring firstly to Figures 1 and 2 there is shown a parts washer according to an embodiment of the apparatus. The parts washer comprises a base 1 and a sink or basin 2. Generally the parts washer will be of such a size that when the base 1 stands on the ground the sink 2 is located at a convenient height for a user who is standing in front of the parts washer. The sink 2 may be provided with a cover (not shown) enabling the sink 2 to be opened and closed as required. The sink 2 is preferably made of metal - for example stainless steel. [0020] In one corner of the sink 2 is provided a wash brush 4. The brush 4 is mounted in the corner of the sink for convenience but in use will be removed and may be operated by a user to clean parts in the sink. The wash brush may be electrically powered and it may preferably be linked with the supply of cleaning agent which may be provided to the sink 2 via the wash brush 4. A filter 5 may be provided to filter cleaning fluid as it is provided to the wash brush. Located preferably centrally in the sink 2 is a drain 3 for returning cleaning fluid which drain 3 may also be provided with a filter. It will be understood that the drain 3 could be provided in a different location. Mounted to one side of the base 1 is a control unit 6, and below the base may be provided a foot-operated pump control switch 7 by means of which a use standing in front of the parts washer may control the supply of cleaning fluid to the sink 2 by pump 8.

[0021 ] Figure 3 shows the parts washer with the sink 2 removed and also without the inner tank which will be described later. The base 1 supports a double- walled tank formed from an outer and inner tank. The outer tank defines a large interior cavity that receives the inner tank with a gap defined between the inner and outer tanks. In this gap is provided a thermal insulating material 15 such that overall tank construction is of a double-wall filled with thermal insulation material to provide optimum thermal control properties.

[0022] Figure 4 shows a front view of the sink 2 with the wash brush 4. To be noted in Figure 4 is an anti-evaporation device 9 that is shown closed in Figure 4(a), open in Figure 4(b) and in detail in Figure 4(c). The anti-evaporation device is pivoted about the sink drain 3 in such a manner that when the sink 2 is not in use a counter- balance just ensures closure between the drain 3 and the anti-evaporation device 9. When the sink is in use the mass of fluid returning back to the inner tank via the drain 3 is sufficient to overcome the mass of the counter-balance and causes the device 9 to open so that cleaning fluid can return to the inner tank. When the flow of cleaning fluid ceases the anti-evaporation device 9 is caused to close again by the counter-balance. This serves to prevent hot vapour from escaping from the inner tank and evaporating into the atmosphere.

[0023] Figure 5 shows the inner tank 10 that is used for holding the cleaning fluid and which is sized so that it is received within the outer tank with the insulating material 15 filling the space between the inner and outer tanks. The inner tank 10 is made of stainless steel and - very generally speaking - is cuboid in shape and has a flat bottom surface. Secured to this under surface is a generally planar heating mat 14 which is secured to the under surface by a mounting plate 12. Optionally between the mounting plate 12 and the under surface of the tank 10 may be provided a heat transfer mat 1 1 . The heating mat 14 may take any known form and may for example be a resistor encapsulated in a silicone rubber, or it may be an aluminium heating block. The heat transfer mat 1 1 may be formed of appropriate rubber, silicone or even metals such as aluminium foil and may be provided to ensure good thermal transfer from the heating mat 14 to the underside of the tank 10 in particular by taking up any spaces of voids caused by any indentations or imperfections in underside of the tank 10.

[0024] In the embodiment shown the heating may 12 is placed underneath the bottom surface of the inner tank 10. Conceivably, however, the heating mat may be placed against a side surface of the inner tank or indeed more than one heating mat may be used with different heating mats placed against different surfaces,

[0025] An important function of the heating mat 12 is to maintain the temperature of the cleaning fluid such that the biological component may remain healthy. Typically this may be from 40 to 45 °C

[0026] An advantage of using a planar heating mat 14 is that heat is applied to a relatively large area of the underside of the inner tank which provides a much more uniform heating of the cleaning fluid and avoids the danger of hotspots in some parts of the tank and other parts of the tank not being heated properly. Temperature control means can be applied by placing thermistors or thermocouples on the mat or in the tank or a combination of the two. In the embodiment shown in the Figures an over- temperature device 13 is provided adjacent the heating mat 14 so as to enable power to the heating mat 14 to be cut off in the event of over-heating of the heating mat 14 for whatever reason. Thermostat 17 (see Figure 6) is provided to monitor the temperature of the heating fluid in the inner tank which information may be provided back to the electrical control 6 which may control the power provided to the heating mat.

[0027] It will be noted from the above description of a preferred embodiment that the sink 2 and the inner tank 10 are preferably made of a metal such as stainless steel. This is advantageous as it is preferable that those parts of the apparatus that come into contact with the cleaning agent should be made of a material that does not adsorp bacteria or other potentially toxic materials. Stainless steel is a suitable such material and it makes cleaning of the parts washer much easier.