The present invention relates to a casing for a heat recovery system and a heat recovery cell by-pass mechanism for a heat recovery system. In particular, the present invention relates to a ceiling-mounted mechanical ventilation and heat recovery unit.

It is an aim of the present invention to provide a casing for a heat recovery system which minimises air leakage and provides for increased efficiency, as well as a heat recovery cell by-pass mechanism which minimises air leakage and improves the efficiency of air flow through the system.

It is a further aim of the present invention to provide a casing for a heat recovery system which allows for easy access to electrical control circuitry of the system and to a heat recovery cell housed inside the casing.

In one aspect the present invention provides a casing for a heat recovery system, the casing comprising : a chamber for accommodating a heat recovery cell; an air inflow inlet in fluid communication with the chamber; an air inflow outlet in fluid communication with the chamber; an air outflow inlet in fluid communication with the chamber; an air outflow outlet in fluid communication with the chamber; and a heat recovery cell by-pass mechanism located between the airflow inlet and the chamber, wherein the heat recovery cell bypass mechanism comprises a first shutter flap which is rotatable between an open position in which air is able to flow through the air inflow inlet, around the first shutter flap and into the chamber, and a closed position in which the first shutter flap prevents air from flowing into the chamber from the air inflow inlet, the first shutter flap being shaped to act as an air guide vane to guide air into the chamber when the first shutter flap is in the open position.

In another aspect the present invention provides a heat recovery cell by-pass mechanism comprising : a first shutter flap; and at least two shaft bearings; the first shutter flap being rotatably mounted between the two shaft bearings, and being rotatable between an open position and a closed position, each bearing having an elongate shape with a longitudinal axis, the first shutter flap having a first and a second end face, the first shutter flap being mounted to generally align the first and second flap end faces of the first shutter flap with the longitudinal axis of each shaft bearing when the first shutter flap is in the closed position, wherein each shaft bearing has a convex profile along an axis generally orthogonal to the longitudinal axis.

In a further aspect the present invention provides a heat recovery cell bypass mechanism comprising : a first shutter flap; and at least two shaft bearings; the first shutter flap being rotatably mounted between the two shaft bearings, and being rotatable between an open position and a closed position, each bearing having an elongate shape with a longitudinal axis, the first shutter flap having a first and a second end face, the first shutter flap being mounted to generally align the first and second flap end faces of the first shutter flap with the longitudinal axis of each shaft bearing when the first shutter flap is in the closed position, wherein each shaft bearing has a convex profile along an axis generally orthogonal to the longitudinal axis.

In a still further aspect the present invention provides a casing for a heat recovery system, the casing comprising : an upper casing section; and a lower casing section, the upper casing section having a lower surface for abutting an upper surface of the of the lower casing section, the lower casing section having a heat recovery cell lower receiving portion and the upper casing section having a heat recovery cell upper receiving portion, the heat recovery cell upper and lower receiving portions together forming a chamber for accommodating a heat recovery cell when the upper surface of the lower casing section and the lower surface of the upper casing section abut, wherein the lower heat recovery cell receiving portion comprises gripping members for gripping a heat recovery cell.

In a yet still further aspect the present invention provides a casing for a heat recovery system, the casing comprising : an electrical enclosure; and a sliding mechanism by which the electrical enclosure is mounted to the casing such that the electrical enclosure is slideable between an inaccessible position in which an opening of the electrical enclosure is covered by the casing to an accessible position in which the opening to the electrical enclosure is uncovered by the casing.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only and with reference to the accompanying drawings, in which :

Figure 1 illustrates a perspective view of a heat recovery system in accordance with a preferred embodiment of the present invention;

Figure 2 illustrates an exploded perspective view of the heat recovery system of Figure 1, with the upper and lower casing sections of the casing being separated;

Figure 3 illustrates a perspective view of the upper casing section of the casing of Figure 1;

Figure 4 illustrates a perspective view of the lower casing section of the casing of Figure 1;

Figure 5 illustrates a perspective view of the shutter flaps of the by-pass mechanism of the heat recovery system of Figure 1;

Figure 6 illustrates an exploded perspective view of the shutter flaps of the by-pass mechanism of the heat recovery system of Figure 1;

Figures 7(a) to (c) illustrate plan view of the shutter flaps of the by-pass mechanism of the heat recovery system of Figure 1, in first, intermediate and second configurations; Figure 8 illustrates in enlarged scale a longitudinal sectional view through a shutter flap part and adjacent bearing of the shutter flaps of the by-pass mechanism of the heat recovery system of Figure 1 ;

Figure 9 illustrates a cross-sectional perspective view through the first shutter flap of the by-pass mechanism of the heat recovery system of Figure 1 ;

Figure 10 illustrates a computational fluid dynamics simulation of air flow directed across the first shutter flap part of the first shutter flap of the bypass mechanism of the heat recovery system of Figure 1 ;

Figures 11(a) to (g) illustrate various views of the bearings of the by-pass mechanism of the heat recovery system of Figure 1 ;

Figure 12 illustrates an end view of a heat recovery system in accordance with a further embodiment of the present invention as a modification of the heat recovery system of Figure 1;

Figure 13(a) to (d) illustrate views of a heat recovery system in accordance with a still further embodiment of the present invention as a modification of the heat recovery system of Figure 1, with the views illustrating operation of the sliding mechanism of the electrical control circuitry.

The heat recovery system comprises a casing 100 and a heat recovery cell 101 which is enclosed within the casing 100 and provides, as will be described hereinbelow, for the transfer of heat from air vented from a building structure to air drawn into the building structure from an outdoor, external environment.

The casing 100 comprises a first casing section 102 and a second casing section 104 which is removably attachable to the first casing section 102. The first casing section 102 has a first surface 105 which provides for fixing to the building structure, such as to a ceiling, and a second surface 106 for abutting a first surface 108 of the second casing section 104.

The second casing section 104 has a first surface 108 which is configured sealingly to engage the second surface 106 of the first casing section 102, such as to provide for a sealing fit between the first and second casing sections 102, 104, and a second surface 109 which faces oppositely to the first surface of the first casing section 102.

The first and second casing sections 102, 104 together define a cavity 110 which receives the heat recovery cell 101.

In this embodiment the first casing section 102 includes a first cavity portion 112 and the second casing section 104 includes a second cavity portion 113, with the cavity portions 112, 113 together defining the cavity 110.

In this embodiment the second cavity portion 113 of the second casing section 104 comprises gripping members 115 for gripping the heat recovery cell 101. In embodiment, as particularly illustrated in Figure 4, the gripping members 115 comprise ribs, here vertical ribs. The provision of gripping members 115 ensures that a heat recovery cell 101 when housed in the cavity 110 formed by the first and second cavity portions 112, 113 is retained in the second casing section 104 when the second casing section 104, here the lower section, is removed for maintenance purposes. This avoids the possibility of the heat recovery cell 101 remaining in the first casing section 102 when the second casing section 104 is removed and subsequently falling, either on to persons below or the floor, causing damage.

In this embodiment the first and second casing sections 102, 104 are moulded from expanded polypropylene (EPP), which is sufficiently smooth as to define highly-efficient airways and sufficiently robust as to form the outer, structural skin of the casing 100. The casing 100 includes an intake 116 which is fluidly connected to an external, atmospheric environment and through which a supply of fresh air is delivered to the heat recovery cell 101, an exhaust 118 which fluidly connected to the atmospheric environment, separately of the intake 116, from which air from within the building structure, having passed through the heat recovery cell 101, is exhausted, a supply 120 which is fluidly connected within the building structure and to which fresh air, having passed through the heat recovery cell 101, is delivered within the building structure, and an extract 122 which is fluidly connected to the building structure, separately of the supply 120, and exhausts air from the building structure through the heat recovery cell 101 and/or a by-pass channel 132, as will be described in more detail hereinbelow.

In this embodiment the extract 122 includes a main channel 131 which is fluidly connected to the cavity 110, and the heat recovery cell 101 as received therewithin, and a second, by-pass channel 132 which is fluidly connected to the exhaust 118.

In this embodiment the casing 100 includes a first fan compartment 136, located between the extract 122 and the exhaust 118, for accommodating a fan 137 to draw air from within the building structure and through the extract 122 and exhaust air through the exhaust 118.

In this embodiment the casing 100 includes a second fan compartment 140, located between the intake 116 and the supply 120, for accommodating a fan 141 to draw fresh air from an external, atmospheric environment through the intake 116 and deliver fresh air, having passed through the heat recovery cell 101, from the supply 120.

In this embodiment the first fan compartment 136 is located within the second casing section 104, but could alternatively be located within the first casing section 102, or between the first and second casing sections 102, 104. In this embodiment the second fan compartment 140 is located within the second casing section 104, but could alternatively be located within the first casing section 102, or between the first and second casing sections 102, 104.

In this embodiment the system further comprises a by-pass mechanism 200 for controlling an extent to which air drawn through the extract 122 passes through the main channel 131 thereof, and hence the heat recovery cell 101, in relation to the by-pass channel 132, and hence directly to the exhaust 118 and so by-passing the heat recovery cell 101.

In this embodiment the by-pass mechanism 200 comprises a shutter flap assembly 201 which comprises a first shutter flap 202 which is located in the main channel 131 of the intake 122 and a second shutter flap 203 which is located in the by-pass channel 132 of the intake 122.

In this embodiment the shutter flap assembly 201 is configurable between a first configuration in which the first shutter flap 202 is in an open configuration, in which air is able to flow through the main channel 131 and the heat recovery cell 101 disposed within the cavity 110, and the second shutter flap 203 is in a closed configuration, in which air is prevented from flowing through the by-pass channel 132, a second configuration in which the first shutter flap 202 is in a closed configuration, in which air is prevented from flowing into the cavity 110, and the second shutter flap 203 is in an open configuration, in which air is able to flow through the by-pass channel 132 to the exhaust 120, and intermediate configurations between the first and second configurations in which the first and second shutter flaps 202, 203 are at intermediate configurations, in which air drawn through the intake 122 is proportionately directed through respective ones of the main and by-pass channels 131, 132 of the intake 122.

With this configuration, the by-pass mechanism 200 allows the heat recovery cell 101 to be by-passed entirely or proportionately in relation to the temperature of the outdoor, external environment, such as to prevent or reduce heating of the incoming, fresh air from the external environment.

In this embodiment the first shutter flap 202 comprises a first flap part 205, which includes an elongate main body 207 and first and second supports 208, here in the form of axial shafts, at the opposite ends of the main body 207, and first and second bearings 209 which are attached to the casing 100 and receive the respective supports 208 of the first flap part 205 such that the first flap part 205 is rotatable about the bearings 209 between open and closed positions.

In this embodiment the first flap part 205 is shaped to act as an air guide vane to guide air into the cavity 110, and hence the heat recovery cell 101, when the first flap part 205 is in the open position.

In this embodiment the first flap part 207 has an asymmetric sectional shape which provides a minimum resistance to the air flow when turning a slight corner on entry into the heat recovery cell 101. By minimizing the resistance to the air flow, the power required to drive the air through the system is minimized.

Figure 10 illustrates a computational fluid dynamics simulation of air flow across a first flap part 207 towards the heat recovery cell 101 located in the cavity 110. This simulation demonstrates how the shaped trailing edge of the first flap part 207 acts as a guide vane to direct air towards the cavity 110 and therefore improves the efficiency of air flow through the heat recovery cell 101.

In this embodiment the first flap part 207 has ends 214 which are configured sealingly to engage the adjacent bearings 209 when the first shutter flap 202 is in the closed configuration. In this embodiment the second shutter flap 204 comprises a second flap part 215, which includes a main body 217 and supports 218, here in the form of axial shafts, at the opposite ends of the main body 217, and first and second bearings 219 which are attached to the casing 100 and receive the respective supports 218 of the second flap part 215 such that the second flap part 215 is rotatable about the bearings 219 between open and closed positions.

In this embodiment the second flap part 217 has ends 224 which are configured sealingly to engage the adjacent bearings 219 when the first shutter flap 202 is in the closed configuration.

In this embodiment the adjacent supports 208, 218 of the first and second flap parts 205, 215 include engagement features 221a, b, optionally in the form of interengaging male and female keys, here in the form of a blade and receptacle joint, which provide that the first and second flap parts 205, 215 have a fixed angular relationship and also allow for axial displacement of the first and second flap parts 205, 215 when mounted in the casing 100, so as to accommodate manufacturing tolerance in the casing 100.

In this embodiment the support 208 of the first flap part 205 includes a female key 221a and the support 218 of the second flap part 215 includes a male key 221b, but alternatively the support 208 of the first flap part 205 could include a male key 221a and the support 218 of the second flap part 215 could include a female key 221b.

In this embodiment the key features 221a, b are formed to have an asymmetric profile, in order to prevent incorrect assembly of the coupling joint.

In this embodiment the adjacent supports 208, 218 of the first and second flap parts 205, 215 are arranged to provide that in one rotational position the first shutter flap 202 is in the open configuration and the second shutter flap 204 is in the closed configuration, and in a second rotational position the first shutter flap 202 is in the closed configuration and the second shutter flap 204 is in the open configuration, and in intermediate rotational positions the first and second shutter flaps 202, 204 are proportionately open or closed, whereby relative fractions of air flow through the main flow channel 131 and the by-pass flow channel 132 are controlled.

In this embodiment the supports 208, 218 of the first and second flap parts 205, 215 each include a detent 225, here in the form of a nib, by which the respective bearings 209, 219 are held captive in axial relation to the supports 208, 218. The detent 225 is located axially in relation to the end face 214, 224 of the respective flap part 205, 215, such as to define a side sealing clearance end float and provide for a required sealing between the respective flap parts 205, 215 and the bearings 209, 219. With this configuration, side sealing between the end faces of the first and second flap parts 205, 215 and the bearings 209, 219 is not dependent on the moulding tolerances of the casing sections 102, 104 of the casing 100.

In this embodiment, as particularly illustrated in Figures 11(a) to (g), the bearings 209, 219 each comprise an elongate body 226 having an engagement face 228 which is adapted to engage the respective end of the adjacent flap part 205, 215 when in the closed position.

In this embodiment the engagement face 228 has a generally convex sectional profile across the lateral extent thereof, whereby sealing engagement between the engagement face 228 and the respective adjacent end 214, 224 of the flap part 205, 215 occurs only when the flap part 205, 215 is brought to the closed position, whereby engagement between the engagement face 228 and the respective adjacent end 214, 224 of the flap part 205, 215 occurs over a limited angular rotation, optionally less than 3, 2 or 1 degrees. This convex profile is such as to minimize the sliding friction between the engagement face 228 and the respective adjacent end 214, 224 of the flap part 205, 215 when the flap parts 205, 215 are moved between the open and closed positions, thus minimizing the force to open or close the respective flap part 205, 215 and allowing for the use of an actuator of lower power.

In this embodiment the body 226 includes a bearing bore 230, here a part- circular bore, in which the respective supports 208, 218 are held captive.

As illustrated in Figure 11, each bore 230 has a bore wall 232 which is drafted, in this embodiment from both ends of the bore 230, such as to provide for radial clearance along part of the axial length of the bore 230, in this embodiment at the outer edges of the bore 230 and so prevent binding between the bore 230 and the respective support 208, 218 should the respective shutter flap parts 205, 215 be deformed either as a result of the thermal environment or as a consequence of the moulding process. With this configuration the bores 230 are self-centring and minimize the frictional resistance, allowing for use of a lower power actuator.

In this embodiment the bearing bore 230 includes an aperture or cut-out 234 which allows the bearing 209, 219 to pass over the support 208, 218 of the respective shutter flap parts 205, 215. In this embodiment the supports 208, 218 of the shutter flap parts 205, 215 include location flats 240 to facilitate fitting of the bearings 209, 219.

In this embodiment the bearings 209, 219 are moulded from a plastic, for example, acrylonitrile butadiene styrene (ABS).

In this embodiment the by-pass mechanism 200 further comprises an actuator 244 for actuating the shutter flap assembly 201.

The system further comprises an electrical control circuit 245 which controls operation of the system.

Finally, it will be understood that the present invention has been described in its preferred embodiments and can be modified in many different ways without departing from the scope of the invention as defined by the appended claims.

In one embodiment at least one, or both, of the first and second casing sections 102, 104, is bowed, such that the lower surface 106 of the first casing section 102 or the upper surface 108 of the second casing section 104 has a convex profile.

In one embodiment, as illustrated in Figure 12, the first, upper casing section 102 is bowed, such that the lower surface 106 of the first casing section 102 has a convex profile, at least in its lateral section.

This bowing of the first and/or second casing sections 102, 104 improves the seal between therebetween by minimising the possibility that bowing arising from the clamping forces or the process of moulding the casing sections 102, 104 results in a concavity of one or both of the casing sections 102, 104, which would otherwise result in air leakage.

In one embodiment, as illustrated in Figure 12, the casing 100 further comprises a clamping mechanism 250 for clamping the first and second casing sections 102, 104 together to ensure abutment of the lower surface 106 of the first casing section 102 with the second, lower surface 108 of the second casing section 104.

In this embodiment the clamping mechanism 250 comprises a plate 252 which extends over the lower surface 109 of the second casing section 104 and clamping fitments 254 which are located at the lateral, longitudinal edges of the first, upper surface 105 of the first casing section 102

In a further embodiment, the electrical control circuit 245 comprises an electrical enclosure 300 and a sliding mechanism 302 by which the electrical enclosure 300 is mounted to the casing 100, such that the electrical enclosure 300 is slideable between an inaccessible position, as illustrated in Figure 13(a), in which an opening 304 of the electrical enclosure 300 is enclosed by the casing 100 to an accessible position, as illustrated in Figure 13(b), in which the opening 304 to the electrical enclosure 300 is clear of the casing 100. With this configuration, the sliding mechanism 302 allows for access to the electrical enclosure 300 from directly below the casing 100 without requiring removal of the casing 100 from the ceiling structure or disassembly of the casing 100.

In this embodiment the electrical enclosure 300 is mounted to a side of the casing 100, in which configuration the opening 304 to the electrical enclosure 300 is covered by the lower and upper casing sections 102, 104 of the casing 100 when the electrical enclosure 300 is in its normal, operative position.