Refrigeration – Muffler or sound dampener
Reexamination Certificate
1999-11-23
2001-11-27
Tapolcai, William E. (Department: 3744)
Refrigeration
Muffler or sound dampener
C181S202000, C181S403000, C417S312000
Reexamination Certificate
active
06321557
ABSTRACT:
The present invention provides housing apparatus for machinery and more especially, but not exclusively, to apparatus for housing refrigerator condenser and compressor units.
As is known, in refrigeration systems a compressor circulates a refrigerant from an evaporator through a condenser and expansion valve and back to the evaporator. A refrigerator essentially contains a compressor to move refrigerant (volatile liquid) around a pipe. Refrigerant leaves the expansion valve at low pressure causing it to evaporate inside the pipe within the evaporator and thereby lose heat. The refrigerant leaves the compressor at high pressure. As it flows through the condenser, the high pressure causes the vapour to condense back to liquid, giving out heat as it does so. Thus, heat flows into the air around the condenser.
Combined compressor and condenser units are used to provide a cooling capacity for refrigerators and freezers within commercial premises for example supermarkets. Typically such compressor and condenser units are situated in a location remote from commercial premises as they are generally large and for this reason are space consuming. Moreover, the units are inherently noisy. Noise pollution has become a major social issue as it has been shown to be detrimental to living and working environments and can have an adverse effect on health.
The noise problem associated with compressor and condenser units can be partially solved by housing such units in sound-proofed constructions. Such constructions are commonly built on the “box within a box” principle, whereby the inner box is completely isolated from the outer in order to provide a high degree of sound insulation. For example, sound-proofing apparatus for housing machinery typically comprise a rigid outer shell lined with an insulating layer such as plastic foam and an inner shape inserted into the outer shell to form a space between the outer and inner shell which is also filled with insulating material. One such sound-proofing apparatus is disclosed in European patent application EP 0062166.
In addition to apparatus which eliminates noise through sound insulation and/or sound absorption, there are systems which actively eliminate noise by generating sound waves having the same amplitude but an opposite phase to the waveforms of the noise thereby cancelling the noise produced. One such active noise control system is disclosed in European patent application EP0612057.
In situations where the sound-proofing apparatus is required to house machinery such as compressor and condenser units, overheating within the internal environment of the apparatus is a problem. Overheating in the environment surrounding the machines is generally sensed by a thermostat causing operation of the machinery to cease. Once sufficient cooling has occurred the machines may restart; however, periods in which the machinery is idle can be extremely costful to business. For example, in the United Kingdom refrigerated food displayed in a supermarket must be maintained at a constant temperature not exceeding 4° C. In situations where the temperature of the food has exceeded this limit, the food is considered unfit for sale for human consumption and should be removed and destroyed.
Attempts have been made to overcome this problem of overheating by housing the machinery in very large ventilated units, in order to provide a large internal area for airflow and heat dissipation from the condenser radiator and compressor components. However, such housing units inefficiently utilise space, a feature which is disadvantageous in commercial premises where optimisation of the use of free space is both cost effective and desirable. The desirable aspect associated with reducing the size of housing units is because such units are, in addition to being large, typically heavy and unsightly. Moreover such unnecessarily large units will suffer from difficulties associated with the mobilisation and transport thereof.
It is an object of this invention to provide apparatus for and a method of efficiently controlling both of the aforementioned problems of noise and overheating generally associated with housing machinery such as compressors and condensers, whilst at the same time limiting the size of such apparatus to a workable minimum.
According to the present invention there is provided noise attenuating apparatus for housing, inter alia, a compressor and/or condenser unit, the apparatus comprising a substantially box-shaped outer shell and an inner shell which houses the unit, the outer shell being formed with a primary air inlet means to receive air into the apparatus and a primary air outlet means for discharge of spent air from the apparatus, the inner shell including an inner chamber and being formed with a secondary air inlet means to receive air supplied via the primary air inlet means into the inner chamber to supply air to the unit, the inner shell also being formed with a secondary air outlet opening for flow of spent air from the inner chamber; the space between the inner and outer shells defining a tortuous flow path for the removal of spent air from the apparatus through the primary air outlet means.
The unit of the invention is typically a noise generating piece of apparatus or equipment such as electrical home appliances, computer systems or compressor and condenser units for refrigerators, freezers and air-conditioning equipment. In a preferred aspect of the invention the unit is a combined condenser/compressor.
The apparatus of the invention may house more than one unit, for example two or three units. Preferably, these units will be positioned side by side in the inner shell such that cool air supplied by the inner chamber is drawn into the units and warm air is discharged for removal from the apparatus. In this way a continuous flow of air through the apparatus is maintained.
The housing apparatus is typically a modular construction comprising at least two enclosures separated by an air space. Preferably the housing apparatus will comprise only two enclosures namely an outer and an inner shell.
The outer shell of the housing apparatus is typically formed of three panels secured together to define a box. In order to achieve optimum sound insulation all joints must be secured to provide an airtight seal. The materials of the panels may be metallic for example stainless or galvanised steel. Other materials may of course be used. Preferably, the materials of the outer shell are reflective in order to reflect sunlight and maintain a cool environment in the apparatus. Moreover, it is possible to achieve good sound insulation using multi-layered constructions for example combinations of steel and plasterboard. The panels are typically lined on their inner surfaces with sound absorptive material such as foam or mineral wool, for example Open Cell Foam (Barafire) and Mineral Wool Slab (Rockseal). Preferably, the panel lining is a non-flammable material.
The inner shell of the housing apparatus is typically formed from at least three panels secured together to provide an airtight acoustic seal. Preferably, the inner shell will comprise four panels including two longitudinal side panels, a front panel and a back panel secured to form a box. Preferably, the back panel is removable to allow for servicing of the unit whilst housed in the apparatus. The width of the inner shell will depend upon the dimensions of the unit(s) housed therein. The preferred unit of the invention will ideally be positioned in the inner shell such that the compressor is disposed adjacent to the inner chamber and the condenser is disposed in front of the compressor toward the front panel of the inner shell. In this preferred arrangement the width of the unit will be such that the outer edges of the unit contact inner surfaces of the inner shell thus serving to limit airflow along the sides of the unit and ensure optimum airflow through the unit. The materials of the inner shell may be sound insulating materials as described for the outer shell.
The housing apparatus may be manufactured by inserti
Parker Ronald Brian
Scrivener Rhys
Lahive & Cockfield LLP
Tapolcai William E.
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