Background Art As shown in Fig. 1, a conventional oscillating fan unit comprises a single fan 3, which consists of a plurality of integrated blades and is connected to the motor shaft of a drive motor 2. The fan 3 is rotated by the drive motor 2, and generates a current of air. The drive motor 2 is encased in a motor housing, while the fan 3 is covered with a protection grill cover 4 mopunted to the frontr end of the motor housing. In the operation of the fan unit, the fan 3 oscillates together with both the motor 2 and the protection grill cover 4 within a predetermined oscillating stroke.

However, the conventional oscillating fan unit is problematic in that the current of air produced by the fan 3 only blows within a limited sectorial area defined by the predetermined oscillating stroke. Furthermore, this conventional oscillating fan unit only allows a person, sitting or standing in front of the fan unit at a fixed position within the limited sectorial area, to be alternately in the current of the fan 3 since the single fan 3 oscillates within the predetermined stroke.

Another problem of the conventional oscillating fan unit resides in that when fan unit is continuously operated for a lengthy period of time, the drive

motor 2 generates a considerable amount of heat, absorbed by the air current produced by the fan 3, thus making a hot current. This hot air current makes a person in said current feel unpleasant.

In an effort to overcome the above-mentioned problems experienced in the conventional oscillating fans, a multi fan unit, designed to produce currents of air blowing in all directions, has been proposed as disclosed in Korean Utility Model Publication No. 86-2860. In the above multi fan unit, a drive bevel gear is mounted to the rear end of a motor shaft, and engages with a plurality of driven bevel gears. A fan shaft, integrated with a fan at one end thereof, is connected to each of the driven bevel gears at the other end thereof, and so a plurality of fans produce currents of air blowing in all directions.

This multi fan unit is advantageous in that the fans simultaneously produce currents of air blowing in all directions. However, this fan unit undesirably allows heat from the motor shaft to be absorbed by the air currents of the fans, and creates hot air currents, so that persons in the hot air currents feel unpleasant. In addition, the rotating force of a drive motor in the above multi fan unit is transmitted to the fans through a gear transmission mechanism fabricated with a common engagement of a plurality of driven bevel gears with one drive bevel gear. Therefore, the gear transmission mechanism of the above multi fan unit undesirably generates operational noise when the fans are rotated at high speeds, thus disturbing persons around the fan unit. In addition, the gear transmission mechanism is excessively loaded during power transmission, and so the fan unit undesirably results in an excessive amount of power loss and is not likely to be continuously operable for a lengthy period of time.

The inventor of this invention thus proposed a multi fan cooling unit in Korean Patent Application No. 93-12930 in an effort to overcome the above- mentioned problems experienced in the conventional multi fan unit.

In the multi fan cooling unit disclosed in document 93-12930, a drive motor having a motor shaft is horizontally set on the bottom support plate of a housing, while a first fan shaft horizontally extends to a first position, spaced upward apart from the motor shaft at a predetermined distance. A first fan is

mounted to the outside end of the first shaft, while both a driven pulley and a first roller are mounted to the inside end of the first shaft.

In addition, a second fan shaft horizontally extends at a second position spaced upward and apart from the first shaft at a predetermined distance. This second shaft is perpendicular to the first shaft. A second fan is mounted to the outside end of the second shaft, while a second roller is mounted to the inside end of the second shaft. A third fan shaft horizontally extends at a third position, spaced downward and apart from the second shaft at a predetermined gap, such that the first and third shafts are in opposite directions. A third fan is mounted to the outside end of the third shaft, while a third roller is mounted to the inside end of the third shaft. In addition, a fourth fan shaft horizontally extends at a fourth position, spaced upward and apart from the first shaft at a predetermined gap, such that the second and fourth shafts are in opposite directions. A fourth fan is mounted to the outside end of the fourth shaft, while a fourth roller is mounted to the inside end of the fourth shaft.

In the above fan unit, the drive pulley of the motor shaft is connected to the driven pulley of the first fan shaft by a main-transmission belt, so that the first shaft is primarily rotatable by the drive motor. On the other hand, the first, second, third and fourth rollers are connected together by a sub-transmission belt.

Therefore, the rotating force of the drive motor is transmitted to the first to fourth shafts through the above-mentioned two transmission belts, and rotates the first to fourth fans at the same time. The above multi fan cooling unit thus prevents currents of air from the fans from absorbing heat from the drive motor, reduces operational noise during the high speed rotating action of the fans, and prevents the power transmission mechanism from being excessively loaded during its power transmission action.

However, the above multi fan cooling unit must be provided with a somewhat complex transmission mechanism consisting of two transmission belts: the main-transmission belt for connecting the drive pulley of the motor shaft to the driven pulley of the first fan shaft and the sub-transmission belt connecting the first, second, third and fourth rollers together.

In order to firmly hold the first to fourth fan shafts within the housing of the above multi fan unit at their predetermined positions, a plurality of support columns must firmly and regularly stand on the outside edge of the bottom support plate of the housing, with a plurality of shaft bearings held by the support columns at predetermined different heights so as to rotatably hold the first to fourth shafts.

Therefore, the entire volume of the fan unit is undesirably enlarged, thus making the fan unit difficult to install on a support surface while undesirably consuming an excessive area.

In addition, the positions of the first to fourth fans in the above multi fan cooling unit are fixed. It is thus impossible for the multi fan cooling unit to generate currents of air blowing in all directions, but the blowing directions of the air currents from the fans are limited to four fixed directions. This reduces the operational effect of the multi fan cooling unit.

Disclosure of the Invention Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art.

A primary object of the present invention is to provide a multi fan cooling unit, which is provided with a plurality of fans mounted to a support column at different heights facing different directions angularly spaced at regular intervals, with the fans also being movable on the axis of the column at an angle of 360°, and which thus produces currents of air blowing uniformly in all directions, and maximizes its operational effect.

Another object of the present invention is to provide a multi fan cooling unit, which is simplified in its construction and is reduced in its volume, thus being easily and effectively placed in a limited space and improving its market competitiveness.

A further object of the present invention is to provide a multi fan cooling unit, which is provided with two motors: a fan drive motor and a column drive motor, and is designed to reliably and steadily apply electric power to the two

motors without twisting the electric wires of the two motors during the rotating action of the support column with the fans.

In order to accomplish the above object, the present invention provides a multi fan cooling unit, comprising a support column having a double pipe structure with both a hexagonal inner pipe and a cylindrical outer pipe and firmly standing upright within a housing; a plurality of fan shafts radially and rotatably mounted to the support column at different heights facing different directions angularly spaced at regular intervals, with both a fan mounted to the outside end of each of the fan shafts and a driven pulley mounted to the inside end of each fan shaft; a fan drive motor set within the lower portion of the housing and having a drive pulley at the motor shaft, with a transmission belt wrapped around the drive pulley of the motor shaft and the driven pulleys of the fan shafts to connect them to each other, thus allowing the fans to be rotatable by the fan drive motor at the same time; a column drive motor set within the lower portion of the housing and used for rotating the support column together with the fan drive motor at an angle of 360° ; and upper and lower power terminal units installed within the lower portion of the housing and used for applying electric power to the fan drive motor and the column drive motor, whereby the fans of the fan shafts produce currents of air blowing uniformly in all directions, and the upper and lower power terminal units reliably and steadily apply electric power to the two motors without twisting the electric wires of the two motors during a rotating action of the support column with the fans.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a side view of a conventional oscillating fan; Fig. 2 is a perspective view, showing the appearance of a multi fan cooling unit in accordance with the present invention;

Fig. 3 is a front sectional view, showing the construction of a multi fan cooling unit having three fans according to the primary embodiment of the present invention; Fig. 4 is an enlarged sectional view of the portion"A"of Fig. 3, showing the construction of a column drive motor of the multi fan cooling unit of this invention; Fig. 5 is a plan sectional view taken along the line B-B of Fig. 3, showing the construction of both a rotatable support column having a double pipe structure and holding the fan shafts of the three fans; Fig. 6 is a perspective view, schematically showing the belt and pulley transmission mechanism used for transmitting the rotating force of a fan drive motor to the driven pulleys of the three fans in the unit of Fig. 3; Fig. 7 is a sectional view, showing the power supplying structure of the multi fan cooling unit of this invention; Fig. 8 is an enlarged sectional view of the portion"D"of Fig. 7, showing the construction of upper and lower power terminal units included in the power supply structure; Fig. 9 is an exploded perspective view of the portion"C"of Fig. 7, showing the structure for mounting the lower end of the support column to a rotary disc; Fig. 10 is an exploded perspective view of the portion"D"of Fig. 7, showing the power supplying structure of the multi fan cooling unit of this invention in detail; Fig. 11 is a front sectional view, showing the construction of a multi fan cooling unit having two fans according to the second embodiment of the present invention; Fig. 12 is a plan sectional view taken along the line E-E of Fig. 11, showing the construction of the support column having a double pipe structure and holding the three fan shafts; and Fig. 13 is a perspective view, schematically showing the belt and pulley transmission mechanism used for transmitting the rotating force of a fan drive

motor to the driven pulleys of the three fans in the unit of Fig. 11.

Best Mode for Carrying Out the Invention Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

Figs. 2 to 10 show the construction of a multi fan cooling unit according to the primary embodiment of the present invention.

As shown in the drawings, the housing of the multi fan cooling unit according to the primary embodiment of this invention is formed by a cylindrical protection grill cover 15 vertically set between a top cover 10 and a lower casing 20.

A rotary disc 50 is concentrically set at the top wall of the lower casing 20, with a fan drive motor Ml mounted to the lower surface of the rotary disc 50.

A lower power terminal unit 30 having a cylindrical shape is interiorly installed on the bottom wall of the lower casing 20, while an upper power terminal unit 40 having a cylindrical shape is mounted to the fan drive motor M1. The rotary disc 50, holding the fan drive motor M1, is rotatable relative to the lower casing 20 as will be described in detail later herein.

Each of the lower and upper terminal units 30 and 40 is provided with a shaft hole 30a or 40a at its center such that the two shaft holes 30a and 40a are aligned with each other so as to commonly receive a central shaft 45 therein. A plurality of annular track grooves 41a, 41b, 41c, 41d and 41e having different diameters are concentrically formed on the lower surface of the upper terminal unit 40, with a plurality of first conductive terminals 42 set between the grooves 41a to 41e and an electric wire 43 connected to each of the first terminals 42.

On the other hand, a plurality of vertical actuation holes 31a, 31b, 31c, 31d and 31e are formed in the lower terminal unit 30 at positions corresponding to the annular track grooves 41a, 41b, 41c, 41d and 41e. A second conductive terminal 36 is set within each of the actuation holes 31a to 31e. Each of the

second conductive terminals 36 is connected to an electric wire 33 through a ground plate 34 and a lead wire 35. A compression coil spring 37 is set within each of the actuation holes 31a to 31e at a position between the second terminal 36 and the ground plate 34 so as to normally bias the second terminal 36 upward to allow said second terminal 36 to elastically project from the actuation hole. The second terminals 36 on the lower terminal unit 30 are thus brought into contact with the first terminals 42 of the upper terminal unit 40.

The motor shaft M2-1 of a column drive motor M2 is fixedly mounted to the center of the lower surface of the top cover 10 as will be described in detail later herein, so that the motor shaft M2-1 is not rotatable, but allows the housing of the column drive motor M2 to be rotatable relative to the fixed motor shaft M2-1 when the motor M2 is electrically activated. A motor bracket 60 covers the column drive motor M2, while a support bracket 65 is centrally mounted to the upper surface of the rotary disc 50. A support column is held by the motor bracket 60 of the top cover at its upper end, and by the support bracket 65 of the rotary disc 50 at its lower end. The above support column has a double pipe structure, with an inner pipe having a hexagonal cross-section and an outer pipe 80 having a circular cross-section. The inner and outer pipes 70 and 80 of the support column are rotatable at the same time by the column drive motor M2.

In the multi fan cooling unit, three shaft holes 71,72 and 73 are diametrically formed on the hexagonal inner pipe 70 at different heights facing different directions regularly spaced out at angles of 120°. Three fan shafts 91,92 and 93 are rotatably set within the three shaft holes 71 to 73, with a driven pulley 91a, 92a or 93a mounted to the inside end of each of the fan shafts 91 to 93. The outside end of each of the fan shafts 91 to 93 projects towards the outside of the outer pipe 80, and holds a fan 91b, 92b or 93b.

A drive pulley 51 is mounted to the motor shaft M1-1 of the fan drive motor M1, mounted on the lower surface of the rotary disc 50, and is connected to the driven pulleys 91a, 92a and 93a of the first to third fan shafts 91 to 93 through a transmission belt V, thus rotating the three fan shafts 91 to 93 at the same time.

The electric wires 33 and 43 of the lower and upper terminal units 30 and

40 are connected to the fan drive motor MI and the column drive motor M2, thus applying electricity to the two motors M1 and M2. In such a case, it is possible to control the rotating speeds (rpm) of the two motors M1 and M2 as desired by the two terminal units 30 and 40.

The electric wire for the column drive motor M2 extends from the upper terminal unit 40 to the motor M2 through a passing hole 66, formed on the support bracket 65 of the rotary disc 50, and the channel between the inner and outer pipes 70 and 80 of the support column.

In the drawings, the reference numeral 13 denotes a shaft bearing having a semicircular cross-section and receiving a semicircular motor shaft M2-1 of the column drive shaft M2 therein such that the bearing 13 holds the shaft M2-1 while preventing any undesired rotating action of the shaft M2-1. The numeral 22 denotes a control panel provided on the sidewall of the lower casing 20, while the numeral 24 denotes a plurality of casters mounted to the bottom wall of the lower casing 20. In addition, the numeral 39 denotes a plurality of wire leading notches for leading the electric wires 33 of the lower terminal unit 30 to the outside of the terminal unit 30, the numeral 44 denotes a plurality of wire leading holes for leading the electric wires 43 of the conductive terminals 42 of the upper terminal unit 40 to the outside of the terminal unit 40, the numeral 52 denotes a mounting bracket for holding the fan drive motor M1 to the upper terminal 40, the numeral 95 denotes a plurality of bearings rotatably supporting the first to third fan shafts 91 to 93 on the hexagonal inner pipe 70 of the support column.

The operational effect of the above-mentioned multi fan cooling unit will be described herein below.

When it is desired to operate the multi fan cooling unit of this invention, the fan drive motor M1 is electrically activated by operating the control panel 22 of the lower casing 20.

The drive pulley 51 of the motor shaft M1-1 of the fan drive motor MI is thus rotated, and so the driven pulleys 91a, 92a and 93a of the first to third fan shafts 91 to 93 are rotated at the same time since the driven pulleys 91a, 92a and 93a are commonly connected to the drive pulley 51 by the single transmission belt

V.

Therefore, the first to third fans 91b, 92b and 93b of the three fan shafts 91 to 93 are rotated at the same time to generate air currents blowing in the three directions.

When it is desired to rotate the support column together with the three fans 91b, 92b and 93b around the vertical axis of the column at an angle of 360°, the column drive motor M2 is electrically activated by operating the control panel 22 of the lower casing 20.

When the control panel 22 of the lower casing 20 is operated to elastically activate the two motors MI and M2 as described above, an electric current is applied to the second conductive terminals 36, which are set within the actuation holes 31a to 31e of the lower terminal unit 30. In such a case, the second conductive terminals 36 are connected to the electric wires 33 through both the ground plates 34 and the lead wires 35, and are normally biased upward by the compression coil springs 37 so as to come into contact with the first terminals 42, provided between the track grooves 41a to 41e of the upper terminal unit 40.

The electric current is thus applied to the column drive motor M2 through some of the electric wires 43 of the upper terminal unit 40, which pass through the passing hole 66 of the support bracket 65 on the rotary disc 50, and through the channel between the inner and outer pipes 70 and 80 of the support column. The column drive motor M2 is thus electrically activated.

In addition, the electric current is also applied to the fan drive motor M1 through the remaining electric wires 43 of the upper terminal unit 40, thus activating the fan drive motor M1. In such a case, it is possible to control the rotating speed of the fan drive motor M1 as desired.

When the column drive motor M2 is electrically activated as described above, the housing of the column drive motor M2 is rotated relative to the motor shaft M2-1 since this motor shaft M2-1 is fixed to the top cover 10. Therefore, the support column, consisting of the hexagonal inner pipe 70 and the cylindrical outer pipe 80, is rotated together with the housing of the column drive motor M2 since the upper end of the column is fixed to said motor housing by the bracket 60.

In such a case, the rotary disc 50 is also rotated in the same direction since the lower end of the support column is fixed to the rotary disc 50 by the bracket 65.

Therefore, the support column with the three fans 91b, 92b and 93b is rotated on its vertical axis at an angle of 360°, and so the air currents from the three fans 91b, 92b and 93b uniformly blow in all directions.

In the multi fan cooling unit of this invention, the upper terminal unit 40 is fixed to the lower surface of the rotary disc, so that the terminal unit 40 is rotatable along with the rotary disc 50. However, the electric connection between the rotatable upper terminal unit 40 and the fixed lower terminal unit 30 is accomplished by the second conductive terminals 36, which are movably set within the actuation holes 31a to 31e of the lower terminal unit 30 while being connected to the electric wires 33 through both the ground plates 34 and the lead wires 35 and being biased upward by the compression coil springs 37 to come into contact with the first conductive terminals 42 provided between the track grooves 41a to 41e of the upper terminal unit 40. Therefore, it is possible to steadily apply electric power from the fixed lower terminal unit 30 to the rotatable upper terminal 40 without twisting the electric wires 33 and 43.

In a brief description, the multi fan cooling unit according to the primary embodiment of this invention is designed such that the driven pulleys of the three fans 91b, 92b and 93b are commonly connected to the drive pulley of the fan drive motor MI through a single transmission belt V, and so the three fans 91b, 92b and 93b are rotatable at the same time by the drive motor M1. In addition, the support column holding the three fans 91b, 92b and 93b is rotatable on its vertical axis at an angle of 360° by the column drive motor M2, and so the air currents from the three fans 91b, 92b and 93b uniformly blow in all directions.

Figs. 11 to 13 are views, showing the construction of a multi fan cooling unit according to the second embodiment of the present invention. As shown in the drawings, the general shape of the multi fan cooling unit according to the second embodiment remains the same as described for the primary embodiment, but the number and positions of the fans are altered to simplify the construction of the multi fan cooling unit. That is, in the multi fan cooling unit of this second

embodiment, two shaft holes 171 and 172 are diametrically formed on the hexagonal inner pipe 70 of the support column at different heights. Two fan shafts 191 and 192 are rotatably set within the two shaft holes 171 and 172 such that the two shafts 191 and 192 are oriented at diametrically opposite directions, with a driven pulley 191a or 192a mounted to the inside end of each of the fan shafts 191 and 192. The outside end of each of the fan shafts 191 and 192 projects towards the outside of the outer pipe 80 of the support column, and holds a fan 191b or 192b. An idle shaft 193, having a middle pulley 193a, is rotatably set on the support column at a predetermined position such that the idle shaft 193 is perpendicular to each of the two fan shafts 191 and 192.

A drive pulley 51 is mounted to the motor shaft M1-1 of the fan drive motor M1, which is mounted on the lower surface of the rotary disc 50. This drive pulley 51 of the motor MI is connected to the two driven pulleys 191a and 192a of the first and second fan shafts 191 and 192 and the single middle pulley 193a of the idle shaft 193 through a single transmission belt V, thus rotating the two fan shafts 191 and 192 at the same time.

In the multi fan cooling unit of this second embodiment, the two fan shafts 191 and 192 are rotatably set on the hexagonal pipe 70 of the support column, with the two fans 191b and 192b mounted to the outside ends of the two fan shafts 191 and 192 projecting towards the outside of the outer pipe 80. The two fans 191b and 192b are rotatable at the same time by the fan drive motor, while the support column together with the two fans 191b and 192b is rotatable on its vertical axis at an angle of 360° by the column drive motor. The air currents from the two fans 191b and 192b uniformly blow in all directions. This second embodiment thus desirably reduces the number of the fans of the multi fan cooling unit while yielding the same operational effect as that expected from the multi fan cooling unit of the primary embodiment.

Due to the reduced number of fans, the multi fan cooling unit of this second embodiment is simplified in its construction and reduced in its volume and size, so that this multi fan cooling unit can be effectively placed in a limited space, such as the top surface of a table.

Industrial Applicability As described above, the present invention provides a multi fan cooling unit. In the multi fan cooling unit, a plurality of fan shafts rotatably set in the hexagonal pipe of a support column at different heights facing different directions angularly spaced at regular intervals, with a fan mounted to the outside end of each of the fan shafts. The fan shafts are commonly connected to a fan drive motor by a single transmission belt, thus being rotatable at the same time by the fan drive motor. In addition, the support column together with the fans is rotatable on its vertical axis at an angle of 360° by a column drive motor. The air currents from the fans thus uniformly blow in all directions, and so the multi fan cooling unit of this invention improves the operational effect.

In the multi fan cooling unit of this invention, the fan shafts are rotatably set in the hexagonal pipe of the support column, so that the multi fan cooling unit is simplified in its construction and is reduced in its volume and size. This multi fan cooling unit is thus easily and effectively placed in a limited space, and is improved in its market competitiveness.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.