Kitchen Ventilation System With Fan Having Positive Pressure-To-Output Characteristic Applied Thereto

Abstract

The present invention relates to a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied. More particularly, the present invention relates to a system for maximizing efficiency of exhausting polluted air at minimum costs by applying a fan having a positive pressure-to-output characteristic to a hood, to improve a ventilation system which is installed vertically in an apartment house to discharge polluted air from kitchen hoods on respective floors to the top of an exhaust duct. The kitchen ventilation system of the present invention comprises an exhaust duct 100 provided at one side of an apartment house, and a hood 200 which is provided in the kitchen on each floor and includes a fan 210 having a positive pressure-to-output characteristic to collect surrounding air and discharge the collected air to the exhaust duct 100. According to the present invention, noise can be reduced and economical efficiency and ventilation performance can also be improved by maximizing efficiency of exhausting polluted air at minimum costs.

Description

TECHNICAL FIELD

The present invention relates to a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied. More particularly, the present invention relates to a system for maximizing efficiency of exhausting polluted air at minimum costs by applying a fan having a positive pressure-to-output characteristic to a hood, to improve a ventilation system which is installed vertically in an apartment house to discharge polluted air from kitchen hoods in respective floors to the top of an exhaust duct, thereby reducing noise and improving economical efficiency and ventilation performance.

BACKGROUND ART

In general, a major source of polluting room air in an apartment house is a variety of harmful materials such as heat, smell and oil vapor, which are produced when a person cooks in the kitchen. To discharge the harmful materials produced in the kitchen to the outside, a hood is installed in the kitchen, and an exhaust duct is also vertically formed on a side of the building to communicate with the kitchen hood.

FIG. 1 is a side sectional view of a conventional kitchen ventilation system.

As shown in FIG. 1, the conventional kitchen ventilation system comprises an exhaust duct 10 which is provided at one side of an apartment house and includes an exhaust fan 11 formed at an upper end thereof, a plurality of hoods 20 each of which is provided in the kitchen on each floor and includes a fan 21 to collect surrounding air and discharge the collected air to the exhaust duct 10, and a plurality of pressure sensors 30 which are provided in the exhaust duct 10 at regular vertical intervals.

As shown in FIG. 1, the conventional kitchen ventilation system so configured allows the harmful and polluted materials, which are produced when a person cooks in the kitchen, to be collected in and discharged to the outside through the exhaust duct 10 vertically formed on one side of the building, by means of the hood 20 mounted with the fan 21 which is installed over a countertop in the kitchen.

At this time, the fan 21 mounted to the hood 20 allows the polluted materials in the kitchen to be collected and discharged to the exhaust duct 10, and the exhaust fan 11 allows the polluted materials in the exhaust duct 10 to be discharged to the outside of the building.

In general, in order to allow the fans 21 of the hoods 20 to smoothly discharge the polluted materials in the kitchen to the outside in a high-rise building of 40 to 50 floors, the fans should exhibit output of power gradually increasing as installation positions are changed from lower floors to higher floors.

However, when the hoods 20 with the same output of power as each other are installed on the lower and higher floors, the output of power of the fan 21 in the hood 20 installed on the lower floors is unnecessarily large to discharge the polluted materials in the kitchen, whereas that installed on the higher floors is insufficient to discharge the polluted materials. Furthermore, there is a problem in that the fan 21 in the hood 20 installed in the kitchen on the higher floors cannot smoothly discharge the polluted materials due to loss of static pressure as well as the noise is too greatly increased.

That is, as load pressure applied to a discharge port of the fan 21 in the hood 20 installed in the kitchen on the higher floors is increased, load applied to the fan 21 is also increased. Therefore, the amount of air discharged is decreased, and thus, the amount of polluted materials discharged is also decreased.

To solve the above problem, the plurality of pressure sensors 30 are additionally installed in the exhaust duct 10 at regular vertical intervals to independently control the output of power of the fans 21 in the hoods 20 according to the pressure detected from the pressure sensors 30.

In case of the conventional kitchen ventilation system in which the plurality of pressure sensors measure air pressure in the exhaust duct at the respective levels to control the output of power of the fan according to the levels, however, there is a technical problem in that total manufacturing costs of the conventional kitchen ventilation system are inevitably high due to the plurality of pressure sensors for measuring the air pressure and a microprocessor for processing signals from the pressure sensors to control the fans.

DISCLOSURE OF INVENTION

The present invention is conceived to solve the aforementioned problem in the prior art. An object of the present invention is to provide a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied, wherein the fan having a positive pressure-to-output characteristic is employed in a kitchen hood on each floor of an apartment house in which a common exhaust duct is used in both lower and higher floors of the apartment house such that polluted air in the kitchen can be effectively discharged without expensive control devices such as a microprocessor or pressure sensors even though different loads are applied to the lower and higher floors, whereby its noise can be reduced and its economical efficiency and ventilation performance can also be improved by maximizing the efficiency of exhausting polluted air at minimum costs.

To achieve the object of the present invention, the kitchen ventilation system comprises an exhaust duct vertically provided at one side of an apartment house, and a hood for collecting surrounding air and discharging the collected air to the exhaust duct, said hood being provided in a kitchen on each floor of the apartment hours and including a fan having a positive pressure-to-output characteristic.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side sectional view of a conventional kitchen ventilation system.

FIG. 2 is a side sectional view of a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to the present invention.

FIG. 3 is a circuit diagram of a fan driving circuit exhibiting a positive pressure-to-output characteristic for use in the kitchen ventilation system to which the fan having a positive pressure-to-output characteristic is applied according to an embodiment of the present invention.

FIG. 4 is a graph illustrating load curves and operating points of the fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to another embodiment of the present invention.

FIG. 6 is a graph illustrating a level/output curve a fan having a positive pressure-to-output characteristic, which is installed at each floor and used in a kitchen ventilation system.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a side sectional view of a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic according to the present invention is applied, and FIG. 3 is a circuit diagram of a fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to an embodiment of the present invention.

FIG. 4 is a graph illustrating load curves and operating points of the fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to an embodiment of the present invention, FIG. 5 is a circuit diagram of a fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to another embodiment of the present invention, and FIG. 6 is a graph illustrating a level/output curve a fan having a positive pressure-to-output characteristic, which is installed at each floor and used in a kitchen ventilation system.

As shown in FIG. 2, a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied comprises an exhaust duct 100 provided at one side of an apartment house, and a hood 200 which is provided in the kitchen on each floor and includes a fan 210 to collect surrounding air and discharge the collected air to the exhaust duct 100.

Hereinafter, the operation of the present invention will be explained with reference to FIGS. 2 to 6.

As shown in FIGS. 2 and 3, the kitchen ventilation system, to which the fan having a positive pressure-to-output characteristic is applied, of the present invention so configured allows the polluted materials, which are produced when a person cooks in the kitchen, to be collected in and discharged to the outside through the exhaust duct 100 vertically formed on one side of the building, by means of the hood 200 mounted with the fan 210 which is installed over a countertop in the kitchen. In addition, the fan 210 provided in the hood 200 allows the polluted materials in the kitchen to be collected and discharged to the outside through the exhaust duct 100.

A back draft damper is installed between the hood 200 and exhaust duct 100 shown in FIG. 2 such that the polluted materials remaining in the exhaust duct 100 can be prevented from flowing back into the room through the hood 200 when the fan 210 of the hood 200 is not in use.

At this time, in order to allow the fans 210 of the hood 200 to smoothly discharge the polluted materials in the kitchen to the outside in a high-rise building of 40 to 50 floors, the fans 210 should exhibit output of power gradually increasing as their installation positions are changed from lower floors to higher floors, as shown in FIG. 6.

To this end, it is preferable to provide the fan 210 having a positive pressure-to-output characteristic in each of the hoods 200 installed in the kitchen on each floor of the building. In such a case, the fan 210 having a positive pressure-to-output characteristic is installed in the hood 200 such that the hood installed in high-rise building can exhibit adequate output of power regardless of its installation level. Therefore, the polluted materials in the kitchen can be effectively discharged to the outside of the building, i.e. to the outside of the exhaust duct 100, without any additional exhaust fan.

The aforementioned fan 210 having a positive pressure-to-output characteristic is preferably controlled by means of a fan driving circuit in which additional microprocessor and pressure sensors are not included. Preferably, the fan 210, which is provided in the hood 200 and has a positive pressure-to-output characteristic, is driven by the fan driving circuit. As shown in FIG. 3, the fan driving circuit of the present invention comprises a 3-phase induction motor 310 for driving the fan 210, a power unit 320 for applying electric power to the 3-phase induction motor 310, a capacitor C2 330 which is connected with the 3-phase induction motor 310 to produce a phase difference between two phases, and an impedance unit 340 which is connected in series with the 3-phase induction motor 310 to produce a constant amount of air discharged even though load applied to the fan 210 is changed.

Preferably, the impedance unit 340 includes capacitor C1 341 and a resistor Ri 342 connected in parallel with the capacitor C1 341.

As shown in FIG. 4, therefore, in cases where lower and higher voltages (respectively refer to curve A and curve B) are applied to the 3-phase induction motor 310 (refer to FIG. 3) according to the load applied to the fan 210, operating points A′ and B′, which are operating on lower and higher voltages, are shown along a load curve C, respectively.

That is, to create a positive pressure-to-output characteristic curve of the kitchen ventilation system mounted with the fan 210 serving as a load of the 3-phase induction motor 310, the impedance unit 340, which includes the capacitor C1 341 and the resistor R1 342 as a serial load, is added to a conventional driving circuit for the 3-phase induction motor 310 including a capacitor. Therefore, an alternating voltage with constant amplitude is applied to the 3-phase induction motor 310 due to voltage distribution of an alternating voltage with constant amplitude and frequency between the 3-phase induction motor 310 including the capacitor C2 330 and the impedance unit 340 serving as load in series therewith.

At this time, the fan driving circuit operates at equilibrium points for the torque and rotating speed relationship due to the positive pressure-to-output characteristic curve shown in FIG. 4. In FIG. 4, a curve C is a load curve of the fan 210, a curve A is an output characteristic curve of the 3-phase induction motor 310 when the lower voltage is applied thereto, and a curve B is an output characteristic curve of the motor when the higher voltage is applied thereto.

The operating principle will be discussed in detail with reference to FIGS. 3 and 4. If the load applied to the fan is increased while the 3-phase induction motor 310 is rotating at a constant frequency at an operating point A′, slip in the 3-phase induction motor 310 is increased. Accordingly, equivalent impedance of the 3-phase induction motor 310 is reduced, and thus, the current is increased.

At this time, the rotating speed of the motor is rapidly increased due to generated torque proportional to the square of current, and thus, the equivalent impedance of the 3-phase induction motor is again increased. Therefore, the voltage distributed to the constant serial load is also increased (refer to curve B), and the motor is rotated at a new operating point B′.

That is, under the load characteristic of the fan 210 having a positive pressure-to-output characteristic as shown in FIG. 4, an applied voltage is increased as the load is increased. Thus, the motor is in a stable state at the operating point where the rotating speed of the motor is higher.

On the contrary, if the load in the fan is decreased, the equivalent resistance is instantly increased and the current is simultaneously decreased. Thus, the rotating speed of the motor is rapidly reduced and the equivalent impedance is also reduced, and the lower voltage is consequently applied to the 3-phase induction motor 310 (refer to a curve A). Accordingly, the motor stably operates at a new operating point A′.

That is, the load applied to the fan is continuously changed, and the operating points can also be maintained between the maximum and minimum speed-to-torque operating points that the 3-phase induction motor 310 can operate.

As shown in FIG. 5, a fan driving circuit for use in a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied according to another embodiment of the present invention further comprises a resistor R2 350 connected in series with the impedance unit 340 and a switch 360 connected in parallel with the resistor R2 350. Accordingly, the switch 360 can interrupt the current flowing in the resistor R2 350.

That is, as shown in FIG. 5, if the switch 360 and resistor R2 350 connected in parallel with each other are added to the fan driving circuit, resistance in the serial load is increased and the 3-phase induction motor 310 is kept at a lower rotating speed. At this time, if the switch 360 is turned on to cut off the current flowing in the resistor R2 350, the voltage distributed to the 3-phase induction motor 310 is rapidly increased and thus the rotating speed of the fan 210 may be rapidly increased.

INDUSTRIAL APPLICABILITY

According to the kitchen ventilation system of the present invention to which a fan having a positive pressure-to-output characteristic is applied, since the fan 210 controlled by the positive pressure-to-output characteristic fan driving circuit is installed in the hood 200 provided in the kitchen of the high-rise building, the fan having a positive pressure-to-output characteristic can perform an active control of the output of power in accordance with a level where the hood 200 is installed. Therefore, there is an advantage in that polluted materials in the kitchens on the respective floors can be easily discharged through the exhaust duct 100 to the outside, because the fan 210 is rotating faster as the installation level is changed from lower floors to higher floors.

Therefore, a fan having a positive pressure-to-output characteristic is employed in the kitchen hood on each floor of an apartment house in which a common exhaust duct is used in both lower and higher floors of the apartment house such that polluted air in the kitchen can be effectively discharged without expensive control devices such as a microprocessor or pressure sensors even though different loads are applied to the lower and higher floors, whereby noise can be reduced and economical efficiency and ventilation performance can also be improved by maximizing the efficiency of exhausting polluted air at minimum costs.

Claims

1. A kitchen ventilation system, comprising:

an exhaust duct vertically provided at one side of an apartment house; and

a hood for collecting surrounding air and discharging the collected air to the exhaust duct, said hood being provided in a kitchen on each floor of the apartment house and including a fan having a positive pressure-to-output characteristic.

2. The kitchen ventilation system as claimed in claim 1, wherein the fan, which is provided in the hood and has a positive pressure-to-output characteristic, is driven by a fan driving circuit which includes a 3-phase induction motor for driving the fan, a power unit for applying electric power to the 3-phase induction motor, a capacitor C2 connected with the 3-phase induction motor for producing a phase difference between two phases, and an impedance unit connected in series with the 3-phase induction motor for producing a constant amount of air discharged even though load applied to the fan is changed.

3. The kitchen ventilation system as claimed in claim 2, wherein the impedance unit includes a capacitor C1, and a resistor R1 connected in parallel with the capacitor C1.

4. The kitchen ventilation system as claimed in claim 2, wherein the fan driving circuit further comprises a resistor R2 connected in series with the impedance unit and a switch installed in parallel with the resistor R2, thereby interrupting a current flowing along the resistor R2.