EP4246065A1

EP4246065A1 - Cassette unit for refrigerated display cabinets with an airflow reversal system

Info

Publication number: EP4246065A1
Application number: EP23162253.1A
Authority: EP
Inventors: Fabio ORTAGGI; Moreno CAPOSALDO
Original assignee: Industrie Scaffalature Arredamenti ISA SpA
Current assignee: Industrie Scaffalature Arredamenti ISA SpA
Priority date: 2022-03-18
Filing date: 2023-03-16
Publication date: 2023-09-20

Abstract

Cassette unit (100) comprising a base (1), a body (2), a compressor (4) and a condenser (5) disposed on the base (1) outside the body (2), an air intake opening (10a) and an air delivery opening (10b), a fan (30), a defrost system, a control unit configured to reverse the direction of rotation of the fan (30) during the defrost cycle, first one-way flow means (61) disposed in correspondence with the air delivery opening (1 0b) that allow for an airflow from the air delivery opening (10b) inside the refrigerated display cabinet and prevent an airflow from the interior of the refrigerated display cabinet to the air delivery opening (10b).

Description

The present invention relates to a cassette unit for refrigerated display cabinets for food products and beverages.
A cassette unit is a complete refrigeration unit (finished machine) for the refrigeration of refrigerated displayers, such as refrigerated display cabinets, refrigerated display cases, refrigerated counters, and the like. The cassette unit comprises components (compressor, condenser, lamination element, evaporator, and control electronics) that are necessary for performing a thermodynamic compression refrigeration cycle. All components are mounted in a single self-supporting structural case/base. The cassette unit is equipped with intake conduits of external air and delivery conduits of cooled air. Such a unit is inserted into the refrigerated display cabinets, in correspondence with air inlet and outlet conduits of the refrigerated display cabinets that generate a flow of cold air in the refrigerated display cabinet for the storage of consumer products.
Before the advent of the cassette units, the components of the refrigeration system were located in different areas of the refrigerated display cabinet, depending on the function they were to perform. With reference to Fig. 1, the cold function (evaporator) is arranged in the product storage area. The hot function (condenser + compressor) is arranged in an engine compartment outside the storage area.
The idea of having both the cold generation components and the heat elimination components in the same area comes from the need to reduce the complexity dictated by the numberless solutions introduced in the realization of the refrigeration systems. One of the main strengths of the cassette unit technology consists in the fact that such a unit is perfectly interfaced with the refrigeration display cabinet, and is a stand-alone unit that does not require the presence of the refrigeration system components (e.g., fan, evaporator) mounted inside the refrigeration display cabinet, thus resulting in easy disassembly, easy accessibility for maintenance and easy replacement on site, in case of failures that cannot be solved immediately.
In addition, the cassette unit meets the ever-increasing demand of the market for eco-sustainability and easy disposal because components and materials in line with the need to have an increasingly reduced environmental impact were evaluated in the study of this solution.
Currently, the global market offers cassette units that differ in the technical installation solutions depending on the type of end product. Figs. 2A, 2B, and 2C illustrate three examples of cassette units (100) installed in a base, on a roof and on a side of a refrigerated display cabinet (300), respectively.
In each case, the refrigerated display cabinet (300) has an interface wall (301) provided with an air intake outlet (301a) from the cassette unit (100) and an air delivery outlet (301b) toward the cassette unit (100). The interface wall (301) may be a bottom wall (Fig. 2A), a roof (Fig. 2B) or a side wall (Fig. 2C) of the refrigerated display cabinet.
Figs. 3A, 3B and 3C illustrate the cassette units (100) of Figs. 2A, 2B and 2C, respectively.
In each case, the cassette unit (100) comprises a base (1) and a body (2) mounted on the base (1). The body (2) defines a compartment (V) wherein an evaporator (3) with a fan (30) is arranged. A compressor (4), a condenser (5) and a second fan (50) are arranged on the base (1) outside the compartment (V) of the body (2).
It should be considered that the evaporator (3) is a heat exchanger that generates cold, whereas the condenser (5) is a heat exchanger that generates heat, and the compressor (4) is a motor that generates heat as well. Therefore, the body (2) is made of heat-insulating material, and a cold zone insulated from the outside is generated inside the body (2).
The compartment (V) of the body (2) communicates with an air intake opening (10a) and an air delivery opening (10b) suitable for being respectively interfaced with the air intake outlet (301a) and the air delivery outlet (301b) of the interface wall (301) of the refrigerated display cabinet. In this way, the fan (30) creates an airflow that is sucked in from the refrigerated display cabinet, enters the compartment (V) of the body, passes through the evaporator (3), is cooled and is fed into the refrigerated display cabinet.
In the cassette units operating at low temperature (T<0°C), ice is formed on the surface of the evaporator (3) due to the deposit of condensation generated by the moisture of the treated air. The ice on the surface of the evaporator acts as a thermal insulator, resulting in an efficiency loss of the heat exchange between the air and the evaporator. Therefore, the ice formed on the evaporator must be removed by means of a defrost system that performs a defrost cycle.
Such a defrost cycle can be performed according to different techniques:

by stopping the compressor (4);
by means of a heating element mounted on the evaporator (3);
by using a hot gas (the hot gas from the compression of the refrigerant performed by the compressor (4) is sent to the evaporator (3)); and
by reversing the cycle (the refrigeration cycle is reversed so that the evaporator (3) becomes a condenser and the condenser (5) becomes an evaporator).

The choice of one of said defrosting systems depends on several factors and variables, such as defrosting speed, energy consumption, and cost.
The defrosting phase of the evaporator (3) arranged in the compartment (V) of the body (2) is a critical element for the storage of products in the refrigerated display cabinet (300), since such a defrosting phase inevitably increases the air temperature inside the refrigerated display cabinet. The higher the temperature increase, the longer the defrosting time will be, with the risk of deteriorating the products contained in the refrigerated display cabinet.
US2007/214823A1 describes a heat exchanging device for refrigerator according to the preamble of claim 1.
US2004/020228A1 discloses a method and apparatus for moving air through a heat exchanger.
WO2015/075205A2 discloses a multi-compartment locker.
US5357767A discloses a low temperature display merchandiser.
The purpose of the present invention is to eliminate the drawbacks of the prior art by providing a cassette unit that is capable of reducing the defrost cycle time of the evaporator.
Another purpose of the present invention is to provide such a cassette unit that is capable of increasing the defrosting efficiency during the defrost cycle.
These purposes are achieved in accordance with the invention with the features of the appended independent claim 1.
Advantageous achievements of the invention appear from the dependent claims.
The cassette unit according to the invention is defined by claim 1.
Further features of the invention will become clearer from the following detailed description, referring to a purely illustrative and therefore non-limiting embodiment, illustrated in the appended drawings, wherein:

Fig. 1 is a diagrammatic perspective view of a refrigerated display cabinet according to the prior art;
Figs. 2A, 2B and 2C are three diagrammatic perspective views of cassette units for installation in a base, on a roof and on a side of a refrigerated display cabinet, respectively;
Figs. 3A, 3B and 3C are sectional views of the cassette units of Figs. 2A, 2B and 2C, respectively;
Fig. 4 is a sectional view along a vertical plane of a cassette unit according to the invention interfaced with an interface wall of a refrigeration display cabinet, which in this case is a bottom wall, during a normal operating cycle;
Fig. 5 is a sectional view of the cassette unit of Fig. 4, along a horizontal plane;
Fig. 6 is a partially interrupted perspective view illustrating the interface wall of the refrigeration display cabinet, a portion of body of the cassette unit and one-way flow means;
Fig. 7 is a perspective view of a plate supporting the one-way flow means;
Fig. 8 is a sectional view as Fig. 4, but during an airflow reversal in a defrost cycle;
Fig. 9 is a sectional view of the cassette unit of Fig. 8 along a horizontal plane;
Figs. 9A and 9B are enlarged details enclosed in circles A and B of Fig. 9, respectively.

With reference to Figs. 4 to 9, a cassette unit according to the invention is described, it being comprehensively indicated with reference numeral 100.
The cassette unit (100) comprises:

a base (1),
a body (2) defining a compartment wherein an evaporator (3) and a fan (30) are arranged,
a compressor (4) and a condenser (5) arranged on the base (1) outside the compartment (V) of the body (2),
an air intake opening (10a) and an air delivery opening (10b) in communication with the compartment (V) defined by the body (2) and suitable for being interfaced with air intake and delivery outlets (301a, 301b) obtained in an interface wall (301) of a refrigerated display cabinet.

The cassette unit also comprises a second fan (50) arranged on the base (1), outside the compartment (V) of the body, to generate an airflow that passes through the condenser (5).
The evaporator (3) is a heat exchanger, e.g., of finned pack type, comprising a plurality of plates (fins) arranged parallel to each other and serpentine ducts passing through the plates. A refrigerant flows in the serpentine ducts and cools the evaporator.
The evaporator (3) is arranged in the compartment (V) so that the compartment (V) is divided into a first chamber (V1) communicating with the air intake opening (10a) and a second chamber (V2) communicating with the air delivery opening (10b).
During the cooling cycle of the refrigerated display cabinet (300), the fan (30) rotates in a first direction so that the air inside the refrigerated display cabinet is sucked in through the air intake opening (10a), enters the first chamber (V1) of the compartment, passes through the evaporator (3), is cooled, and flows into the second chamber (V2) of the compartment; then, the cold air is expelled through the air delivery opening (10b) to enter the refrigerated display cabinet.
The fan (30) is arranged in the second chamber (V2) of the compartment, in front of the air delivery opening (10b), and rotates in the first direction, for instance in a clockwise direction, to create an airflow from the first chamber (V1) to the second chamber (V2) and then the air that is sucked in by the fan is ejected from the air delivery opening (10b) located behind the fan.
During the cooling cycle of the refrigerated display cabinet (300), the evaporator (3) works at temperatures below 0 °C and therefore it freezes.
The cassette unit (100) is provided with a defrost system of the evaporator (3) of known type, as described above with reference to the prior art.
According to the invention, the cassette unit (100) comprises a control unit configured to reverse the direction of rotation of the fan (30) during a defrost cycle.
As shown in Fig. 9, during the defrost cycle, the fan (30) rotates in a second direction, e.g. in a counterclockwise direction, opposite the first direction of rotation. In such a way, the fan (30) pushes the air from the second chamber (V2) towards the first chamber (V1).
The cassette unit according to the invention comprises first one-way flow means (61) arranged at the air delivery opening (10b) that allow for an airflow from the air delivery opening (10b) to the interior of the refrigerated display cabinet and prevent an airflow from the interior of the refrigerated display cabinet to the air delivery opening (10b).
In view of the above, when the fan (30) rotates in the second direction, the air delivery opening (10b) is closed and thus the air cannot flow out of the compartment (V) through the air delivery opening (10b) to enter the refrigerated display cabinet, ensuring the maximum efficiency of the airflow confined in the compartment (V) of the body of the cassette unit.
Advantageously, the cassette unit may also comprise second one-way flow means (62) arranged at the air intake opening (10a) that allow for an airflow from the interior of the refrigerated display cabinet to the air intake opening (10a) and prevent an airflow from the air intake opening (10a) to the interior of the refrigerated display cabinet.
In this way, when the fan (30) rotates in the second direction, also the air intake opening (10a) closes and thus the air cannot flow out of the compartment (V) through the air intake opening (10a) into the refrigerated display cabinet, thus ensuring the maximum efficiency of the airflow confined in the compartment (V) of the body of the cassette unit.
Referring to Figs. 5 and 9, the body (2) has a first side wall (21) and a second side wall (22) opposite each other.
The evaporator (3) has a first side wall (31) and a second side wall (32) opposite to each other.
A first lateral space (11) suitable for allowing the air to pass through is provided between the first side wall (31) of the evaporator and the first side wall (21) of the body.
A second lateral space (l2) suitable for allowing the air to pass through is provided between the second side wall (32) of the evaporator and the second side wall (22) of the body.
Both the first lateral space (11) and the second lateral space (l2) communicate with the first and second chambers (V1, V2) of the compartment of the body.
With reference to Fig. 9, during the defrost cycle, when the fan (30) rotates in the second direction, the air passes through the lateral spaces (l1, l2), lapping the side walls (31, 32) of the evaporator. This creates two swirling flows through the evaporator. In fact, the air is pushed peripherally by the fan (30) toward the lateral spaces (l2, l2), and then the air enters the first chamber (V1) and passes centrally through the evaporator (3) to be sucked in centrally by the fan (30). Such air vortices generated by the lateral spaces (l1, l2) maximize the defrosting of the evaporator (3) during the defrost cycle.
However, with reference to Fig. 5, during the cooling cycle, the two lateral spaces (l1, l2) should be closed to prevent the air from going from the first chamber (V1) into the second chamber (V2) without passing through the evaporator (3). For such a purpose, the cassette unit (100) comprises third one-way flow means (63) arranged in the first space (11) and fourth one-way flow means (64) arranged in the second space (l2).
The third one-way flow means (63) and the fourth one-way flow means (64) are configured to allow for an air flow from the second chamber (V2) to the first chamber (V1) and prevent and airflow from the first chamber (V1) to the second chamber (V2). Therefore, in the first lateral space (11) and in the second lateral space (l2), an airflow is allowed from the second chamber (V2) to the first chamber (V1) and no airflow is allowed from the first chamber (V1) to the second chamber (V2).
With reference to Figs. 6 and 7, the first one-way flow means (61) are obtained by means of a floating wing (8b) arranged over a grille (7b) disposed in the air delivery outlet (301b) of the interface wall of the refrigerated display cabinet. In this way, if air is delivered toward the refrigerated display cabinet (300), the floating wing (8b) rises, allowing the air to pass through. In contrast, if air is sucked in toward the cassette unit (200), the floating wing (8b) is brought in contact with the grille (7b) and the air is not allowed to pass through.
Similarly, the second one-way flow means (62) are obtained by means of a floating wing (8a) arranged under a grille (7a) disposed in the air intake outlet (301a) of the interface wall of the refrigerated display cabinet. The floating wing (8a) moves in this way: if air is delivered toward the refrigerated display cabinet, the floating wing (8a) rises, going in contact with the grille (7a) and preventing the air to pass through. Conversely, if air is sucked in toward the cassette unit, the floating wing (8a) lowers, allowing the air to pass through.
In such a case, the grilles (7a, 7b) are obtained in a plate (7) that is placed in a slot (303) of the interface wall (301) of the refrigerated display cabinet. The floating wings (8a, 8b) can be elastic membranes mounted on the plate (7).
Referring to Fig. 9A, the third one-way flow means (63) are obtained by means of a floating wing (8c) arranged in front of a grill (7c) between the first chamber (V1) of the compartment of the body and the first lateral space (11). In this way, if the air is sucked in by the fan (30), generating an airflow from the first chamber (V1) to the first space (11), the floating wing (8c) is brought in contact with the grille (7c), blocking the passage of the air. In contrast, if the air is delivered by the fan, generating an airflow from the first space (11) toward the first chamber (V1), the floating wing (8c) opens and allows the air to pass through.
Referring to Fig. 9B, the fourth one-way flow means (64) are obtained by means of a floating wing (8d) arranged in front of a grille (7d) between the first chamber (V1) of the compartment of the body and the second lateral space (I2). In this way, if the air is sucked in by the fan (30), generating an airflow from the first chamber (V1) to the second lateral space (l2), the floating wing (8d) is brought in front of the grille (7d), blocking the passage of air. On the other hand, if the air is delivered by the fan (30), generating an airflow from the second space (l2) toward the first chamber (V1), the floating wing (8d) opens and allows the air to pass through.
Such floating wings (8c, 8d), may also be elastic membranes.
When the defrost cycle is started, the control unit commands a reversal of the direction of rotation of the fan (30), consequently causing a reversal of the airflow in the compartment (V) of the body. Therefore, the first one-way flow means (61) prevent a possible intake of air from the air delivery opening (10b).
In such a condition, the fan (30) becomes a pressing fan that operates in the compartment (V), without any air intake from the outside of the compartment. In this case, with reference to a characteristic curve (prevalence-flow rate) of a fan, the fan (30) operates near the maximum prevalence and with a flow rate of almost zero.
The air outflow from the air delivery opening (10b) on the opposite side is almost entirely cancelled, and air recirculation is created in the compartment (V) of the body through the lateral spaces (l1, l2) in which the third and fourth one-way flow means (63, 64) operate, allowing the air to pass only during the reversal of the airflow.
The airflow is recirculated inside the evaporator (3), generating a closed system in the compartment (V). Therefore, by recirculating in the compartment (V) of the body, the airflow exchanges more thermal energy with the ice of the evaporator (3) due to increased convective motions and to the closed system. In such a way, the ice of the evaporator (3) melts more rapidly. Consequently, such a situation allows to reduce the defrosting time compared to a normal cycle without the airflow reversal system.
Equivalent variations and modifications may be made to the present embodiments of the invention, within the scope of a person skilled in the art, but still within the scope of the invention as expressed by the appended claims.

Claims

Cassette unit (100) comprising:
- a base (1),

- a body (2) defining a compartment (V) wherein an evaporator (3) is disposed, dividing the compartment (V) into a first chamber (V1) and a second chamber (V2),

- a compressor (4) and a condenser (5) disposed on the base (1) outside the body (2),

- an air intake opening (10a) and an air delivery opening (10b), respectively communicating with the first chamber (V1) and the second chamber (V2) of the compartment (V) of the body (2) and suitable for being interfaced with an air intake outlet (301a) and an air delivery outlet (301b) obtained in an interface wall (301) of a refrigerated display cabinet,

- a fan (30) disposed in the compartment (V) and configured to rotate in a first direction of rotation in such a way to allow for an airflow from the first chamber (V1) to the second chamber (V2) that enters the air intake opening (10a), passes through the evaporator (3), and exits from the air delivery opening (10b), and

- a defrost system suitable for performing a defrost cycle wherein the evaporator (3) is heated to melt the ice that is formed on the evaporator,
characterized in that said cassette unit (100) further comprises:
- a control unit configured to reverse the direction of rotation of the fan (30) during the defrost cycle, in such a way that the fan (30) rotates in a second direction opposite the first direction to allow for an airflow from the second chamber (V2) to the first chamber (V1), and

- first one-way flow means (61) disposed in correspondence with the air delivery opening (10b) that allow for an airflow from the air delivery opening (10b) inside the refrigerated display cabinet and prevent an airflow from the interior of the refrigerated display cabinet to the air delivery opening (10b), in such a way that when the fan (30) rotates in the second direction, the first one-way flow means (61) close the air delivery opening (10b) and consequently the air cannot exit from the compartment (V) through the air delivery opening (10b) to enter the refrigerated display cabinet.
The cassette unit (100) according to claim 1, wherein the first one-way flow means (61) comprise a floating wing (8b) disposed on a grille (7b) arranged in the air delivery outlet (301b) of the interface wall of the refrigerated display cabinet.
The cassette unit (100) according to claim 1 or 2, further comprising second one-way flow means (62) disposed in correspondence with the air intake opening (10a) that allow for an airflow from the interior of the refrigerated display cabinet to the air intake opening (10a) and prevent an airflow from the air intake opening (10a) inside the refrigerated display cabinet, in such a way that when the fan (30) rotates in the second direction, the second one-way flow means (62) close the air intake opening (10a) and consequently the air cannot exit from the compartment (V) through the air intake opening (10a) to enter the refrigerated display cabinet.
The cassette unit (100) according to claim 3, wherein the second one-way flow means (61) comprise a floating wing (8a) disposed in contact with a grille (7a) arranged in the air intake outlet (301a) of the interface wall of the refrigerated display cabinet.
The cassette unit (100) according to claim 4 when dependent on claim 2, wherein said grilles (7a, 7b) are formed in a plate (7) disposed in a slot (303) of the interface wall (301) of the refrigerated display cabinet and the floating wings (8a, 8b) are elastic membranes mounted on the plate (7).
The cassette unit (100) according to any one of the preceding claims, wherein:
- the body (2) has a first side wall (21) and a second side wall (22) opposite to each other;

- the evaporator (3) has a first side wall (31) and a second side wall (32) opposite to each other;

- a first lateral space (11) is provided between the first side wall (31) of the evaporator and the first side wall (21) of the body to allow for an airflow;

- a second lateral space (l2) is provided between the second side wall (32) of the evaporator and the second side wall (22) of the body to allow for an airflow.
The cassette unit (100) according to claim 6, further comprising:
- third one-way flow means (63) disposed in the first lateral space (11) and suitably configured to allow for an airflow from the second chamber (V2) to the first chamber (V1) and prevent an airflow from the first chamber (V1) to the second chamber (V2); and

- fourth one-way flow means (64) disposed in the second lateral space (l2) and suitably configured to allow for an airflow from the second chamber (V2) to the first chamber (V1) and prevent an airflow from the first chamber (V1) to the second chamber (V2).
The cassette unit (100) according to claim 7, wherein the third one-way flow means (63) comprise a floating wing (8c) disposed in front of a grille (7c) between the first chamber (V1) of the compartment of the body and the first lateral space (11).
The cassette unit (100) according to claim 7 or 8, wherein the fourth one-way flow means (64) comprise a floating wing (8d) disposed in front of a grille (7d) between the first chamber (V1) of the compartment of the body and the second lateral space (I2).