JP7593234B2 - Air Supply System - Google Patents

Description

The present invention relates to an air supply system.

Conventionally, a room such as a store is provided with an air supply system. The air supply system includes an air supply fan and a differential pressure detection sensor. The air supply fan supplies outside air to the inside of the store. The differential pressure detection sensor detects the pressure difference between the inside and outside of the store.

In this type of air supply system, the differential pressure sensor detects the pressure inside the store and drives the air supply fan to make the pressure inside the store equal to the pressure outside the store (atmospheric pressure) or greater than the pressure outside the store (atmospheric pressure), thereby creating positive pressure in the store (see, for example, Patent Document 1).

JP 2001-153441 A

However, in the above-mentioned air supply system, the air supply fan was driven based on the detection results of the differential pressure detection sensor, so a differential pressure detection sensor was required for each air supply fan to be driven. Therefore, when applying the air supply system to a large store with a large indoor area, it was necessary to install multiple air supply fans to ensure a sufficient supply of outside air to the inside of the store, which required the installation of multiple differential pressure detection sensors as well. As a result, the need to install not only air supply fans but also multiple relatively expensive differential pressure detection sensors resulted in increased manufacturing costs.

In view of the above, the present invention aims to provide an air supply system that can be applied to relatively large target rooms and that can suppress increases in manufacturing costs.

In order to achieve the above object, the air supply system of the present invention is an air supply system including a differential pressure detection sensor that detects the differential pressure between the inside and outside of a target room, a main air supply fan that supplies outside air to the inside of the target room, and a control unit that drives the main air supply fan at a frequency within a predetermined operating tolerance range so that the differential pressure detected by the differential pressure detection sensor approaches a predetermined target value. The system also includes at least one auxiliary air supply fan that is provided separately from the main air supply fan and supplies outside air to the inside of the target room, and the control unit drives the auxiliary air supply fan when the time during which the main air supply fan is continuously driven at the maximum frequency of the operating tolerance range while only the main air supply fan is driven is equal to or longer than a predetermined first reference time, while the control unit stops driving the auxiliary air supply fan when the time during which the main air supply fan is continuously driven at the minimum frequency of the operating tolerance range while both the main air supply fan and the auxiliary air supply fan are driven is equal to or longer than a predetermined second reference time.

The present invention is also characterized in that, in the above-mentioned air supply system, when the time during which the main air supply fan is continuously driven at the maximum frequency of the allowable operating range while only the main air supply fan is driven is less than the first reference time, the control unit continues to drive only the main air supply fan, whereas when the main air supply fan and the auxiliary air supply fan are driven, when the time during which the main air supply fan is continuously driven at the minimum frequency of the allowable operating range is less than the second reference time, the control unit continues to drive the main air supply fan and the auxiliary air supply fan.

The present invention is also characterized in that in the above air supply system, the control unit drives the main air supply fan so that the differential pressure detected by the differential pressure detection sensor approaches zero.

The present invention is also characterized in that in the above air supply system, when the control unit drives the auxiliary air supply fan, it drives it at a preset frequency.

According to the present invention, there is provided at least one auxiliary air supply fan that is provided separately from the main air supply fan and supplies outside air to the inside of the target room, and the control unit drives the main air supply fan at a frequency within a predetermined operating tolerance range so that the differential pressure detected by the differential pressure detection sensor approaches a predetermined target value. When the time during which the main air supply fan is continuously driven at the maximum frequency of the operating tolerance range while only the main air supply fan is driven is equal to or exceeds a predetermined first reference time, the control unit drives the auxiliary air supply fan, and when the time during which the main air supply fan is continuously driven at the minimum frequency of the operating tolerance range while both the main air supply fan and the auxiliary air supply fan are driven is equal to or exceeds a predetermined second reference time, the control unit stops driving the auxiliary air supply fan. This makes it possible to drive the main air supply fan while driving the auxiliary air supply fan as necessary without increasing the number of relatively expensive differential pressure detection sensors, which has the effect of being applicable to relatively large target rooms and suppressing increases in manufacturing costs.

FIG. 1 is a schematic diagram showing an air supply system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a typical control system of the air supply system according to the embodiment of the present invention. FIG. 3 is a flowchart showing the process of controlling the drive of the auxiliary air supply fan performed by the control unit shown in FIG.

The following describes in detail a preferred embodiment of the air supply system according to the present invention with reference to the attached drawings.

Figure 1 is a schematic diagram showing an air supply system according to an embodiment of the present invention, and Figure 2 is a block diagram showing a characteristic control system of the air supply system according to an embodiment of the present invention.

The air supply system illustrated here is intended for a store 1, such as a convenience store or supermarket. Such a store 1 is equipped with an air conditioner and an entrance/exit (not shown in the figure), as well as an exhaust device 10.

The air conditioning system adjusts the temperature, humidity, cleanliness, etc. of the air (hereinafter referred to as the inside air) inside the store 1 (hereinafter referred to as the inside of the store) to keep it in a comfortable state, and is equipped with an indoor unit. The indoor unit is installed on the ceiling or the like inside the store, and is connected through a refrigerant pipe to an outdoor unit installed outside the store 1 (hereinafter referred to as the outside of the store). In such an air conditioning system, the refrigerant circulates between the indoor unit and the outdoor unit while repeatedly compressing, condensing, adiabatic expanding, and evaporating, thereby adjusting the temperature of the internal air, etc.

The entrance is provided in a part of the exterior wall 2 of the store 1. This entrance is for customers of the store 1 to enter and exit the store. Inside the store, a cooking area where food is prepared and product storage devices such as showcases are installed.

A plurality of exhaust devices 10 (five in the illustrated example) are provided, each equipped with an exhaust flow path 11 at a location spaced apart from one another. The exhaust flow path 11 is provided in the attic in a manner that connects the inside of the store with the outside, and an exhaust fan 12 is provided midway along the path. The exhaust fan 12 is driven by operating an operating unit (not shown) installed in the store 1 for the purpose of ventilating the store 1 and discharging odors, etc. When the exhaust fan 12 is driven, this type of exhaust device 10 draws in internal air from an inlet 13 of the exhaust flow path 11, passes it through the exhaust flow path 11, and then discharges it outside the store.

The exhaust device 10 has been described as having an exhaust flow path 11 that connects the inside of the store with the outside of the store, but the exhaust device 10 may also be configured by installing an exhaust fan, also known as a ventilation fan, in an exhaust hole formed in the exterior wall 2 of the store (target room) 1. In this case, the opening of the exhaust hole facing the inside of the store becomes the inlet, and by driving the exhaust fan, internal air is introduced through the inlet and exhausted outside the store.

The air supply system is composed of a differential pressure detection device 20, a main air supply device 30, an auxiliary air supply device 40, and a control unit 50. The differential pressure detection device 20 is equipped with a differential pressure detection duct 21 and a differential pressure detection sensor 22.

The differential pressure detection duct 21 is installed in the attic in a manner that connects the inside of the store with the outside of the store. This differential pressure detection duct 21 has an opening 23 at one end facing the inside of the store and an opening 24 at the other end facing the outside of the store. This differential pressure detection duct 21 allows air to flow along its own axial direction.

The differential pressure detection sensor 22 is disposed at any point in the differential pressure detection duct 21 and detects the pressure difference between inside and outside the store. This differential pressure detection sensor 22 provides the detection result to the control unit 50 as a differential pressure signal.

The main air supply device 30 is equipped with a main air supply flow path 31. The main air supply flow path 31 is installed in the attic in a manner that connects the inside of the store with the outside of the store, and one end faces the outside of the store and is provided with a first outside air inlet 32. The main air supply flow path 31 branches into two midway and the other end of each faces the inside of the store and is provided with a first air supply port 33.

In addition, a main air supply fan 34 is disposed in the main air supply flow path 31 between the first outside air inlet 32 and the branch point. The main air supply fan 34 is driven by a main air supply fan motor 34a, which is a drive mechanism, operating in response to commands given by the control unit 50.

When the main air supply fan 34 is driven, this main air supply device 30 draws in outside air through the first outside air inlet 32, passes it through the main air supply flow path 31, and then blows it out into the store through the first air supply port 33.

The auxiliary air supply device 40 is disposed at a location separated from the main air supply device 30. This auxiliary air supply device 40 is provided with an auxiliary air supply flow path 41. The auxiliary air supply flow path 41 is provided in the attic in a manner that connects the inside of the store with the outside of the store, and one end faces the outside of the store and is provided with a second outside air intake port 42, and is branched into two midway, each of which faces the inside of the store and is provided with a second air supply port 43.

In addition, an auxiliary air supply fan 44 is disposed in the auxiliary air supply flow path 41 between the second outside air inlet 42 and the branch point. The auxiliary air supply fan 44 is driven by an auxiliary air supply fan motor 44a, which is a drive mechanism, operating in response to a command given by the control unit 50.

When the auxiliary air supply fan 44 is driven, this type of auxiliary air supply device 40 draws in outside air through the second outside air inlet 42, passes it through the auxiliary air supply flow path 41, and then blows it out into the store through the second air supply port 43.

The control unit 50 controls the overall operation of each part of the air supply system according to the programs and data stored in the memory unit 55, and includes a main air supply fan drive control unit 51 and an auxiliary air supply fan drive control unit 52.

The main air supply fan drive control unit 51 drives the main air supply fan motor 34a via the inverter device 35 based on the differential pressure signal provided by the differential pressure detection sensor 22 so that the differential pressure approaches a target value (e.g., 0 Pa).

Here, the main air supply fan drive control unit 51 drives the main air supply fan motor 34a via the inverter device 35 at a frequency within a predetermined operating tolerance range (e.g., 20 Hz to 60 Hz) so that the differential pressure approaches the target value, thereby increasing or decreasing the rotation speed of the main air supply fan 34 using PID control.

The auxiliary air supply fan drive control unit 52 includes a judgment processing unit 52a and an auxiliary air supply fan drive processing unit 52b. The judgment processing unit 52a judges whether to drive the auxiliary air supply fan 44 when the auxiliary air supply fan 44 is stopped, and judges whether to stop the auxiliary air supply fan 44 when the auxiliary air supply fan 44 is driven.

In more detail, when only the main air supply fan 34 is being driven, i.e., when the auxiliary air supply fan 44 is stopped, the judgment processing unit 52a judges whether the time T1 during which the main air supply fan 34 is continuously driven by the main air supply fan drive control unit 51 at the maximum frequency (e.g., 60 Hz) of the allowable operating range (hereinafter also referred to as the maximum frequency continuous drive time) is equal to or greater than a first reference time, which is a threshold value read from the memory unit 55, and when it is determined that T1 is equal to or greater than the first reference time, it judges to drive the auxiliary air supply fan 44, whereas when it is determined that T1 is less than the first reference time, it judges to keep the auxiliary air supply fan 44 stopped.

When the main air supply fan 34 and the auxiliary air supply fan 44 are stopped, the judgment processing unit 52a judges whether the time T2 during which the main air supply fan 34 is continuously driven by the main air supply fan drive control unit 51 at the minimum frequency (e.g., 20 Hz) of the allowable operating range is equal to or longer than a second reference time, which is a threshold value read from the memory unit 55, and judges to stop driving the auxiliary air supply fan 44 when it judges that T2 is equal to or longer than the second reference time, whereas it judges to maintain driving of the auxiliary air supply fan 44 when it judges that T2 is shorter than the second reference time.

The auxiliary air supply fan drive processing unit 52b issues a drive command or a drive stop command to the auxiliary air supply fan motor 44a to drive or stop the auxiliary air supply fan 44 at a preset rotation speed. In other words, the auxiliary air supply fan drive control unit 52 performs on/off control to drive or stop the auxiliary air supply fan 44 at a preset frequency.

The control unit 50 may be realized, for example, by having a processing device such as a CPU (Central Processing Unit) execute a program, i.e., by software, or may be realized by hardware such as an IC (Integrated Circuit), or may be realized by a combination of software and hardware.

In an air supply system configured as described above, when at least one exhaust device 10 is operating, the main air supply fan drive control unit 51 of the control unit 50 drives the main air supply fan motor 34a via the inverter device 35 at a frequency within the allowable operating range to drive the air supply fan in response to a differential pressure signal provided by the differential pressure detection sensor 22 so that the differential pressure approaches a target value (e.g., 0 Pa), i.e., so that the pressure inside the store is equivalent to the pressure outside the store (atmospheric pressure). Outside air introduced from the first outside air inlet 32 passes through the main air supply flow path 31 and is blown into the store from the first air supply port 33.

In this case, it is preferable that the first air intake 33 is disposed closer to the inlet 13 than the air outlet of the air conditioner. By disposing the first air intake 33 closer to the inlet 13 than the air outlet of the air conditioner, most of the outside air blown out from the first air intake 33 is introduced into the exhaust passage 11 through the inlet 13 and exhausted outside the store without circulating inside the store.

In other words, the amount of air that is blown into the store through the main air supply device 30 and circulates within the store can be reduced, thereby reducing the amount of outside air that enters the store.

The control unit 50 then continuously performs the following auxiliary air supply fan drive control process, provided that a predetermined time has elapsed through the built-in clock unit.

Figure 3 is a flowchart showing the process of controlling the drive of the auxiliary air supply fan performed by the control unit 50 shown in Figure 2.

In this auxiliary air supply fan drive control process, the auxiliary air supply fan drive control unit 52 of the control unit 50 determines whether or not only the main air supply fan 34 is driven (step S101). Note that the above description of the operation only describes the drive of the main air supply fan 34, so at this point in time, this corresponds to a state in which only the main air supply fan 34 is driven.

If it is determined that only the main air supply fan 34 is operating (step S101: Yes), the auxiliary air supply fan drive control unit 52 calculates the maximum frequency continuous drive time T1 through the judgment processing unit 52a (step S102), and determines whether this calculated T1 is equal to or greater than the first reference time read from the memory unit 55 (step S103).

If it is determined that T1 is equal to or greater than the first reference time (step S103: Yes), the auxiliary air supply fan drive control unit 52 determines through the judgment processing unit 52a to drive the auxiliary air supply fan 44, sends a drive command to the auxiliary air supply fan motor 44a through the auxiliary air supply fan drive control unit 52 to drive the auxiliary air supply fan 44 (step S104), and then returns the procedure to end the current processing.

According to this, outside air from outside the store is introduced through the second outside air inlet 42, passes through the auxiliary air supply flow path 41, and is blown into the store through the second air supply port 43.

In this case, it is preferable that the second air intake 43 is disposed closer to the inlet 13 than the air outlet of the air conditioner. By disposing the second air intake 43 closer to the inlet 13 than the air outlet of the air conditioner, most of the outside air blown out from the second air intake 43 is introduced into the exhaust flow path 11 through the inlet 13 and exhausted outside the store without circulating inside the store.

In other words, the amount of air that is blown into the store through the main air supply device 30 and circulates within the store can be reduced, thereby reducing the amount of outside air that enters the store.

By supplying outside air into the store through the auxiliary air supply flow path 41, the pressure inside the store increases, which causes the frequency of the main air supply fan motor 34a, which is driven at a frequency within the allowable operating range by PID control in the main air supply fan drive control unit 51, to decrease, and the drive rotation speed of the main air supply fan 34 decreases.

On the other hand, if it is determined that T1 is less than the first reference time (step S103: No), the auxiliary air supply fan drive control unit 52 maintains the current state and then returns the procedure to end the current process. As a result, outside air is supplied to the store by driving only the main air supply fan 34.

In the above auxiliary air supply fan drive control process, if the auxiliary air supply fan drive control unit 52 of the control unit 50 determines that only the main air supply fan 34 is not driving (step S101: No), it determines whether the main air supply fan 34 and the auxiliary air supply fan 44 are driving (step S105).

If it is determined that the main air supply fan 34 and the auxiliary air supply fan 44 are operating (step S105: Yes), the auxiliary air supply fan drive control unit 52 calculates the minimum frequency continuous drive time T2 through the judgment processing unit 52a (step S106), and determines whether this calculated T2 is equal to or greater than the second reference time read from the memory unit 55 (step S107).

If it is determined that T2 is equal to or greater than the second reference time (step S107: Yes), the auxiliary air supply fan drive control unit 52 determines through the judgment processing unit 52a to stop driving the auxiliary air supply fan 44, sends a drive stop command to the auxiliary air supply fan motor 44a through the auxiliary air supply fan drive control unit 52 to stop driving the auxiliary air supply fan 44 (step S108), and then returns the procedure to end the current processing.

As a result, the supply of outside air through the auxiliary air supply passage 41 is restricted, which causes the frequency of the main air supply fan motor 34a, which is driven at a frequency within the allowable operating range by PID control in the main air supply fan drive control unit 51, to increase, and the drive rotation speed of the main air supply fan 34 moves in the direction of increasing.

On the other hand, if it is determined that T2 is less than the second reference time (step S107: No), the auxiliary air supply fan drive control unit 52 maintains the current state and then returns the procedure to end the current process. As a result, outside air is supplied to the store by driving the main air supply fan 34 and the auxiliary air supply fan 44.

As described above, according to the air supply system of the embodiment of the present invention, the auxiliary air supply device 40 is provided separately from the main air supply device 30, and the control unit 50 drives the main air supply fan 34 at a frequency within a predetermined operating tolerance range so that the differential pressure detected by the differential pressure detection sensor 22 approaches the target value. When the maximum frequency continuous drive time of the main air supply fan 34 is equal to or longer than the first reference time while only the main air supply fan 34 is being driven, the control unit 50 drives the auxiliary air supply fan 44, and when the minimum frequency continuous drive time is equal to or longer than the second reference time while both the main air supply fan 34 and the auxiliary air supply fan 44 are being driven, the control unit 50 stops driving the auxiliary air supply fan 44. This makes it possible to drive the main air supply fan 34 and the auxiliary air supply fan 44 as necessary without increasing the size of the relatively expensive differential pressure detection sensor 22, which is applicable to relatively large stores 1 and suppresses increases in manufacturing costs.

The above describes a preferred embodiment of the present invention, but the present invention is not limited to this and various modifications can be made.

In the above-described embodiment, there is one auxiliary air supply device 40, but in the present invention, multiple auxiliary air supply devices 40 may be provided.

In the above-described embodiment, the target value is set to, for example, 0 Pa, and the main air supply fan 34 is driven so that the pressure inside the store is equivalent to the pressure outside the store (atmospheric pressure). However, in the present invention, the target value is not limited to 0 Pa, and the main air supply fan may be driven so that the target value is a predetermined value and the pressure inside the store is greater than the pressure outside the store.

1...Store (target room), 10...Exhaust device, 20...Differential pressure detection device, 21...Differential pressure detection duct, 22...Differential pressure detection sensor, 30...Main air supply device, 31...Main air supply flow path, 34...Main air supply fan, 34a...Main air supply fan motor, 35...Inverter device, 40...Auxiliary air supply device, 41...Auxiliary air supply flow path, 44...Auxiliary air supply fan, 44a...Auxiliary air supply fan motor, 50...Control unit, 51...Main air supply fan drive control unit, 52...Auxiliary air supply fan drive control unit, 52a...Determination processing unit, 52b...Auxiliary air supply fan drive processing unit, 55...Memory unit.

Claims (4)

A differential pressure detection sensor that detects the differential pressure between the inside and outside of the target room;
A main air supply fan that supplies outside air to the inside of the target room;
and a control unit that drives the main air supply fan at a frequency within a predetermined operational tolerance range so that the differential pressure detected by the differential pressure detection sensor approaches a predetermined target value,
At least one auxiliary air supply fan is provided separately from the main air supply fan and supplies outside air to the inside of the target room;
The control unit drives the auxiliary supply air fan when the time that the main supply air fan continues to operate at the maximum frequency of the acceptable operating range while only the main supply air fan is driven is equal to or longer than a predetermined first reference time, and stops driving the auxiliary supply air fan when the main supply air fan and the auxiliary supply air fan are driven and the time that the main supply air fan continues to operate at the minimum frequency of the acceptable operating range is equal to or longer than a predetermined second reference time. The control unit continues to drive only the main air supply fan when the time during which the main air supply fan is continuously driven at the maximum frequency of the allowable operating range while only the main air supply fan is driven is less than the first reference time, whereas the control unit continues to drive the main air supply fan and the auxiliary air supply fan when the time during which the main air supply fan is continuously driven at the minimum frequency of the allowable operating range while both the main air supply fan and the auxiliary air supply fan are driven. The air supply system of claim 1. The air supply system according to claim 1 or 2, characterized in that the control unit drives the main air supply fan so that the differential pressure detected by the differential pressure detection sensor approaches zero. The air supply system according to any one of claims 1 to 3, characterized in that the control unit drives the auxiliary air supply fan at a preset frequency.

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