GB2313908A - Fan units for forming an air curtain - Google Patents

Abstract

A fan comprises blowing units, each including a casing 6, an electric motor 7 incorporated into the casing and an axial impeller 8 coupled to the motor for generating an air flow from an inlet toward outlet nozzles 4, and a guide 3 which projects into the casing to arrange the nozzles 4 in a parallel pattern; wherein each nozzle 4 has a heating element arranged therein so that the heating element can contact an airflow passing through the nozzles 4. The heating element may be a planar heating element formed in the guide 3 (see figure 9, not shown). The heating element may have a lourve function to change the discharging direction of the passing air flow (see figures 10-11, not shown).

Description

FAN The present invention pertains to the technical field of a fan for forming an air curtain at an opening of a building.

Such an air curtain is formed by cross flow fans with air flowing across impellers or axial fans. In case of using the axial fans, a structure which has been disclosed in e.g. JP-A-63-13603 has been adopted.

Specifically, as shown in Figure 12 of the accowpanying drawings, axial fan units 101 which are respectively constructed to work as an independent fan are arranged in a row to provide a collective fan as a whole. Although it is difficult to modify the entire length of a collective fan in case of using the cross flow fans, the arrangement bf the units 101 as just above mentioned allows the entire length to be easily modified by increasing or decreasing the number of the units 101 or adjusting spacing between the units 101.

The air curtain is discharged directly downward or downward at an angle with respect to the vertical direction as needed. The discharging direction of the air curtain is changed by adjusting the direction of outlets of the collective fan. In practice, changing the discharging direction is dealt with by adjusting a mounting angle of the collective fan to a building, or providing rotatable louvers at a downstream side of the collective fan, which is disclosed in the publication.

From the viewpoint that a person who passes through the air curtain in winter is exposed to fast cold air and feels extremely cold, some collective fans have a heater incorporated thereinto to heat the air. Cross flow fans have the same arrangement as a hot air heater adopted thereinto for heating, discharging a heated air curtain.

Each guide 102 which is formed as a flow divider has a reflecting plate 103 and a heater 104 incorporated therein to irradiate heat downward even in the axial fan type of the publication as shown in Figure 13, preventing a person from feeling cold.

The conventional collective fan with axial fans in a row as stated earlier creates some problems. One of them is that it is difficult to take measures to prevent a person from feeling cold. In order to obtain heated air in the arrangement shown in Figure 13, each unit 101 has to be provided with means for generating heated air though an air curtain itself remains cold and coldness can not be modulated drastically. On the other hand, when the collective fan is installed at a door way and the like of a walk-in refrigerator, it is not necessary obtain heated air. Under the circumstances, it is disadvantageous in terms of cost and production to cope with those two contradictory purposes by providing two types of fans.

Another is that when the collective fan has a heater incorporated therein to obtain heated air, a heater supporting structure and its accessory parts are needed in addition to requirement of a heat-resistant structure, which cannot meet the demands for a decrease in cost and compaction. Because two rows of air flows are blown out, collective fans for industrial use which are operated by three-phase alternating current has difficulty in the number of heaters in terms of load balance of three-phase alternating current supply. It is difficult to equalise the temperatures of two rows of air curtains.

It is an object of the present invention to eliminate the disadvantages of the conventional collective fan and to provide a new and improved fan capable of easily modifying a fan with axially fans arranged therein into a fan to obtain heated air.

According to the present invention, there is provided a fan comprising: a plurality of blowing units, each comprising: a square hollow casing having one end open to form an inlet for an air flow and the opposite end open to form an outlet; an electric motor within the casing and an axial impeller coupled to the motor for generating an air flow from the inlet toward to outlet; and a guide which projects into the casing to divide the outlet into a plurality of parallel slit nozzles; wherein the blowing units are coupled together at adjacent sides thereof in a row and each nozzle has a heating element arranged therein so that the heating element can contact an airflow passing through the nozzle.

The heating element may comprise a planar heating element which is formed in the guide. The heating element may have a louvre function to change the discharging direction of the passing air flow.

The invention will be further described by way of non-limitative example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of the fan according to a first embodiment of the present invention, portions of the fan being omitted; Figure 2 is an exploded perspective view of the structure of the main portion of the fan according to the first embodiment; Figure 3 is an enlarged sectional view of a portion of the fan according to the first embodiment as viewed in the longitudinal direction; Figure 4 is an enlarged sectional view of the fan according to the first embodiment as viewed in the width direction; Figure 5 is an electrical circuit diagram of the fan according to the first embodiment; Figure 6 is a perspective view of a sheathe heater usable in the fan according to the first embodiment; Figure 7 is a perspective view of a portion of the fan in a modified form according to the first embodiment; Figure 8 is a perspective view of a portion of the fan in another modified form according to the first embodiment; Figure 9 is an enlarged perspective view of a guide in the fan according to a second embodiment of the invention; Figure 10 is an enlarged sectional view of the sheathe heater according to a third embodiment; Figure 11 is an enlarged sectional view of the sheathe heater in a modified form according to the third embodiment; Figure 12 is a perspective view of a conventional fan; Figure 13 is a sectional view of the conventional fan.

Now, the present invention will be described in detail in reference to embodiments shown in the accompanying drawings.

EMBODIMENT 1 In Figure 1, there is shown an exploded perspective view of the fan according to a first embodiment of the present invention, portions of the fan being omitted. In Figure 2, there is shown an exploded perspective view of a portion of the fan. In Figure 3, there is shown an enlarged sectional view of a portion of the fan in the longitudinal direction. In Figure 4, there is shown an enlarged sectional view of the fan in the width direction. The fan is constituted by having a plurality of blowing units laterally arranged in a row in a housing 1 which is formed in an elongated frame body with upper and lower ends opened. The housing 1 is made of sheet metal. The housing has stepped receivers provided therein at a forward end and a rear end of the upper opened portion, and the lower opened portion is formed by inwardly bent portions at the front and rear ends to be narrower than the upper opened portion as shown in Figure 4. Free ends of the inwardly bent portions at the front and rear ends project into the housing upward. The housing 1 may have a dividable structure wherein a combination of an elongated hole and a bolt (not shown) which are provided in overlapping portions can adjust the entire length of the fan within a range defined by the length of the elongated hole.

The respective blowing units 2 are all formed in the same shape and the same size. Specifically, each blowing unit 2 has such a structure that an electric motor 7 driven in three-phase alternating current and an axial impeller 8 thereon are incorporated into a squarely hollow metallic casing 6 which has an upper end opened as a square inlet and a lower end opened downward as outlets 5 in a form of slit-shaped parallel nozzles 4, the nozzles being formed in rows at the front and rear sides on the lower end by providing an angled guide 3 projecting into the casing, as shown in Figures 1 and 2.

The casing 6 has stepped portions formed at upper front and upper rear positions therein to be received and supported by the stepped receivers of the housing 1, and has engaged portions (not shown) formed at a lower portion therein to be engaged with free ends of the bent portions at the front and rear sides of the housing 1 from upwardly. The guide 3 in each casing 6 continuously extends at the lower portion of the casing 6 in the horizontal direction, and the guide works to branch an air flow path in the casing 6 into flows directed into the parallel nozzles 4 by means of slanted surfaces of the guide. Each casing 6 has opposed side walls 9, which respectively have two round holes 10 as heater mounting openings formed therein at a position corresponding to an upstream portion of the outlet 5 of each parallel nozzle 4. The opposed paired round holes which are formed in the opposed side walls 9 for the respective parallel nozzle 4 are arranged in alignment with each other.

To the inlet of each casing 6 is mounted a metallic inlet part as a lid by fitting, which includes an upper square and flat flange 11 with a bellmouth 12 integrally formed at a central portion thereof. The bellmouth 12 of the inlet part forms a substantially circular inlet 13 and the upper flange 11 has an upper surface integrally formed at suitable positions with projections for mounting a guard in a detachable manner. The bellmouth 12 itself extends in a cylindrical shape to project into the casing 6 so as to surround an outer periphery of the axial impeller 8 mounted to the motor 7. To an outer periphery of the outlet side of the bellmouth 12 is fitted a thin, square and flat metallic closure plate 14 which is slightly smaller than the upper flange 11. The closure plate 14 has outer end surfaces in close contact with an inner surface of the casing 6 by mounting the inlet part to the casing 6, and a space which is formed between the outer periphery of the bellmouth 12 and the inner surfaces of the casing 6 is closed by the closure plate 14 and the upper flange 11 in each casing.

In each casing 6, equalizing plates 15 are arranged at an intermediate portion of the guide 3 to extend between the guide 3 and an inner wall at the front end and between the guide 3 and an inner wall at the rear end.

The fan is constituted by housing and arranging a plurality of the blowing units 2 in a row in the housing 1, and the entire length of the fan can be adjusted by an easy operation such as adjustment of spacing between adjoining blowing units 2. The guides 3 in the respective blowing units 2 are continuous one another, and have electrical equipment such as a capacitor and a terminal board, and wiring as shown in Figure 5 collectively arranged therein. The wiring is constituted by a heater energizing circuit 16 and a motor energizing circuit 17 which are provided power from a three-phase alternating current supply. The motor energizing circuit 17 has such an arrangement that the respective motors 7 are connected in parallel with three single-phase alternating current supplies U, V and W. The heater energizing circuit 16 is constituted by a first heat circuit 19 and a second heater circuit 20 fed from the respective single-phase alternating current supplies U, V through a circuit breaker 18 such as a relay, and a third heater circuit 21 and a fourth heater circuit 22 connected in parallel and fed from the remaining singlephase alternating current supply W through the circuit breaker 18. The first to fourth heater circuits are connected in parallel with the motor energizing circuit 17 through the circuit breaker 18. In Figure 5, reference numeral 23 designates a thermostat, and reference numeral 24 designates a thermal fuse.

Mounting the fan can be carried out by mounting metal fittings to two positions of an upper portion of an opening of a building, hooking engagement portions of supporting arms 25 over engagement pieces provided on the metal fittings and bolting the engagement portions and the engagement pieces together as shown in Figure 4.

In the fan according to the present invention, the respective parallel nozzles 4 in each blowing unit 2 form two rows of parallel nozzle array 26 as a whole to discharge two rows of air flows forming an air curtain.

It is possible to easily give a heating function to the fan so as to make the air curtain hot. In detail, the respective groups of four holes which are formed in the respective opposite side walls of each blowing unit 2 are in alignment with each other one by one. Four bar-like sheath heaters 27 as shown in Figure 6 are inserted into the respective groups of four holes so as to run from one of the groups to the other, being arranged in parallel with each other. Each sheath heater 27 has both ends connected to the heater energizing circuit 16 outside the outer side walls of the casings 6 of the outermost blowing units 2, forming the first, second, third and fourth heater circuits 19, 20, 21 and 22. The first and third heater circuits 19 and 21 are arranged in one of the rows in the parallel nozzle array 26, and the second and fourth heater circuits 20 and 22 are arranged in the other row. In that manner, the three-phase alternating current supply is balanced in terms of load, and the respective parallel nozzle array 26 can discharge hot air at an equalized temperature to form a hot air curtain which is free from discomfort due to unequal temperature distribution.

The paired holes 10 in each hole group in each parallel nozzle 4 are arranged side by side in the first embodiment to establish such a state that the sheath heaters 27 traverse related air flow paths. As a result, each air flow can collide against the related sheath heaters 27 to obtain heat transfer effectively.

The holes may be arranged one above the other as shown in Figure 7 (The heaters are indicated by chain-dotted lines). In this case, pressure loss in the air flow can be minimized at the sheath heater 27. Adoption of an arrangement intermediate between both arrangements may have a good relationship between heat transfer and pressure loss. The sheath heaters 27 are relatively long. Absence of a supporting structure for the sheath heaters introduces the danger of the sheath heaters being vibrated due to collision with the air flow created by the axial impeller 8 to become unstable and be broken.

In accordance with the first embodiment, the sheath heaters 27 are highly stable without arranging a special supporting structure because the side walls 9 of the casing 6 in each blowing unit 2 support the sheath heaters 27 at a short distance. The arrangement according to the first embodiment allows the sheath heaters 27 to be supported without arrangement of an extra supporting structure, and the air curtain to be warmed with a sample structure, minimizing an increase in cost. If it is not necessary to make the air curtain warm, the holes 10 are closed by grommets or other members which can be readily detachable.

Although in the first embodiment explanation has been made for the case of using a three-phase alternating current supply, it is easy to modify the first embodiment so as to use ordinary household power. In this case, the special connection in the heater energizing circuit 16 as stated above is not necessary. If it is necessary to further improve the stability of the sheath heaters 27, each blowing unit has the respective equalizing plates 15 formed at an upper portion with holes or recesses to provide heater supporting structures 28 as shown in Figure 8 with the heaters indicated by chain-dotted lines, shortening the supporting distance for the sheath heaters 27 and further enhancing the stability of the sheath heaters 27.

EMBODIMENT 2 In accordance with a second embodiment of the present invention, the fan described and shown as the first embodiment is modified so that portions of the parallel nozzles 4 in each blowing unit 2 which contact with the air flow are constituted by a heating element developing heat due to energization as shown in Figure 9. Other parts than those required to have a function to obtain heated air are the same as the first embodiment.

Identical or similar parts are indicated by the same reference numerals as the first embodiment, and explanation about those parts is omitted for simplicity.

In the second embodiment, the guide 3 has an upper angled portion 29 constituted by a planar heating element 30 as shown in Figure 9 50 as to develop heat due to energization. Such a planar heating element 30 may be prepared by incorporating a heating wire in an aluminum plate, incorporating a sheath heater 27 in an aluminum substrate by die casting or spreading out a flexible planar heating element on a steel sheet and the like.

Although in the example shown, the angled portion of the guide 3 in each blowing unit 2 is constituted by the planar heating element 30, the respective guides 3 may be constituted by a single planar heating element 30 in the entirety of the fan. Other parts are the same as those of the first embodiment.

In accordance with the second embodiment, no increase in the number of required parts is introduced. Making the air curtain warm is possible without increasing pressure loss because the guides 3 which have their original purpose as air flow dividers develop heat. An increase in cost can be minimized. Similar function and similar advantage can be also obtained even if portions of the parallel nozzles 4 except for the guides 3 are constituted by similar planar heating elements 30. The other functions are the same as of those of the first embodiment, and explanation on these functions is omitted.

EMBODIMENT 3 In accordance with a third embodiment, in the fan described and shown with respect to the first embodiment, the sheath heaters 27 also have a function to change the direction of air flow as louvers for changing the direction of passing air flow as shown in Figure 10.

Other parts than parts required for obtaining such a function are the same as those of the first embodiment.

Identical or similar parts are indicated by the same reference numerals as the first embodiment, and explanation about those parts is omitted for simplicity.

Specifically, in the third embodiment, the sheath heaters 27 themselves are formed in a bar-like shape to have a rhombus cross section as shown in Figure 10 so as to have a shape similar to an ordinary louver, or the sheath heaters 27 are covered by auxiliary parts 31 with a louver function as shown in Figure 11 so as to have a shape similar to an ordinary louver. The sheath heaters 27 are supported so as to be rotatable. In practice, the respective auxiliary parts 31 can be made of an elastic material and attached to the respective sheathe heaters 27 through openings 32 thereof using elastic deformation to facilitate assemblage in a convenient manner. By such an arrangement, the direction of the air curtain discharged from the parallel nozzles 4 can be changed using the function of the sheath heaters 27 as louvers, improving the function of the fan by at least sufficient number of parts. The other basic functions are the same as those of the first embodiment, and explanation on those functions is omitted for simplicity.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims (3)

1. A fan comprising: a plurality of blowing units, each comprising: a square hollow casing having one end open to form an inlet for an air flow and the opposite end open to form an outlet; an electric motor within the casing and an axial impeller coupled to the motor for generating an air flow from the inlet toward to outlet; and a guide which projects into the casing to divide the outlet into a plurality of parallel slit nozzles; wherein the blowing units are coupled together at adjacent sides thereof in a row and each nozzle has a heating element arranged therein so that the heating element can contact an airflow passing through the nozzle.

2. A fan according to claim 1, wherein the heating element is a planar heating element formed in said guide.

3. A fan according to claim 1 or 2, wherein the heater has a louvre function to change a discharging direction of the passing air flow.