Ventilation fan automatic control device

Abstract

To solve the problems that in an energy-saving point of view, efficiency is extremely deteriorated and electric power is excessively consumed by a conventional ON-OFF control method of stopping operation of a ventilation fan in a non-operating time zone such as holiday and night time while operating a ventilation fan at a maximum rated exhaust amount in a work time zone or a facility operating time zone in a large-volume facility such as factory and storehouse.SOLUTION: By retrofitting a general-purpose PLC control device and an inverter and incorporating a temperature sensor and a rain sensor with a control device, a high energy-saving effect can be created by appropriately adjusting the number of revolutions of blades of a ventilation fan according to work conditions and / or environmental conditions.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an automatic ventilation fan control device for energy conservation that can be retrofitted for ventilation fans used to improve the environment within large-volume facilities such as factories and warehouses. [Background technology]

[0002] Ventilation fans installed in large-volume facilities such as factories and warehouses are used to exhaust high-temperature air from the facility to bring it closer to an appropriate temperature for work, and to improve the working environment by expelling unpleasant mist. However, most of these ventilation fans are operated at their maximum rated exhaust volume when in use, but are stopped when not in use, which is what is known as ON-OFF control. Furthermore, even if the exhaust volume is changed by automatic control, fully automating it requires highly sensitive sensors for temperature, oil smoke, odor, gas, etc., as well as precise room and outside temperature detectors and a sophisticated control mechanism, making it a high-cost device product. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-166332 [Patent Document 2] Japanese Patent Application Publication No. 4-260739 Summary of the Invention [Problem to be solved by the invention]

[0004] In large-volume factories and warehouses, the conventional ON-OFF control method, in which ventilation fans are operated at the maximum rated exhaust volume during work hours or when equipment is in operation, but are stopped during non-operational hours such as holidays and at night, is extremely inefficient from an energy-saving perspective and consumes excessive amounts of electricity. Even during non-operating hours, when it rains, rainwater mist can enter the factory, increasing humidity and potentially having a negative impact on products and equipment, so in some cases the ventilation fans had to be operated at their maximum rated exhaust volume. Therefore, as shown in Patent Document 1, a device has been proposed that includes sensors to detect temperature, smoke, odors, and gases, which are considered to be factors that deteriorate the indoor environment, a mechanism to set and store cleanliness levels for each of these factors, a mechanism to calculate each contamination level, and a device that compares each contamination level with the previous cleanliness level and comprehensively determines the exhaust volume of the ventilation fan.However, such a device requires expensive sensors and microcomputer control, making it excessively high quality and extremely expensive for improving the working environment at a factory level. Furthermore, as shown in Patent Document 2, the method of controlling ventilation volume by measuring the lowest temperature of the day using a temperature detection sensor and estimating whether the season is summer or winter may work in small spaces, but in large facility environments, ventilation may be insufficient during really hot times of the day. In addition, complex calculations are required for fully automatic control, making this a device that is over-qualified and extremely expensive for improving the working environment at the factory level. [Means for solving the problem]

[0005] This invention is an energy-saving device for ventilation fans that aim to improve the working environment in large-volume facilities such as factories and warehouses.The inverters attached to each ventilation fan are centrally controlled by a general-purpose PLC control device (PLC), and the rotation speed of one or more ventilation fan motors is adjusted appropriately, thereby optimizing the exhaust volume using the minimum amount of electricity required. This device is simple and inexpensive, and can be retrofitted to existing ventilation fans.

[0006] The present invention makes it possible to efficiently operate ventilation fans used in large-capacity facilities such as factories and warehouses, thereby achieving energy savings. [Brief explanation of the drawings]

[0007] [Figure 1] Example of a ventilation fan [Figure 2]Example of automatic ventilation fan control flow chart [Figure 3] Configuration diagram of this device DETAILED DESCRIPTION OF THE INVENTION

[0008] An example of a ventilation fan is shown in Figure 1. There are a wide variety of types of ventilation fans, such as roof fans that are attached to the roofs of factories and warehouses, and types that are attached to walls, but the product of the present invention can be attached to any type of ventilation fan.

[0009] An example of an automatic control flowchart for this device is shown in Figure 2. Note that the number of ventilation fans that can be automatically controlled depends on the control capabilities of the PLC, so it is necessary to select the PLC specifications according to the output and number of ventilation fans to be controlled.

[0010] First, an equipment operation calendar or a work calendar is input into an appropriately selected PLC control device so that it can be determined based on actual time whether the relevant factory is in an operating or non-operating time zone.

[0011] Furthermore, during factory operating hours, if the room temperature is above 31°C, the inverter controls the ventilation fan motor to operate at 50Hz AC to achieve the maximum rated exhaust volume. Similarly, when the temperature is between 20°C and 30°C, the fan motor operates at 35Hz AC. When the temperature is below 19°C, the fan motor operates at 25Hz AC. This information is input into the PLC to control the operation. Naturally, the frequency of the inverter-controlled AC current can be set arbitrarily to suit the room temperature conditions, from the fan motor rotation speed required to achieve the maximum rated exhaust volume to the motor rotation speed required to achieve the minimum required exhaust volume, depending on the factory environment and the specifications of the ventilation fan used.Furthermore, the room temperature conditions for controlling the required rotation speed can also be set arbitrarily and in any number of stages depending on the factory environment and the ventilation fan used.

[0012] Furthermore, even during non-operating hours, if the rain sensor detects rainfall, the ventilation fan motor is controlled to run at the minimum 25Hz required to maintain the products and equipment inside the facility. This is not necessary in facilities that are completely airtight and have mechanisms in place to circulate the air within the facility and prevent areas of stagnation where humidity can accumulate, but using a ventilation fan is an advantageous way to circulate air within the facility simply and inexpensively. [Example]

[0013] Furthermore, the ventilation fan is controlled to stop operating completely only during non-operating hours and when the rain sensor does not detect rain.

[0014] Figure 3 shows the configuration of this device. It has a simple and inexpensive configuration in which inverters are installed to control the motor rotation speed of multiple ventilation fans within the facility, and these are controlled by a single general-purpose PLC. The PLC control simply controls the rotation speed of each ventilation fan's drive motor from the inverter using information from a calendar timer and temperature and rain sensors installed in appropriate locations. As can be seen from this configuration, this automatic control device can also be installed as a retrofit on existing ventilation fans, making it possible to easily and inexpensively achieve energy-saving effects on ventilation fans already in use in large-volume facilities.

[0015] In order to confirm the effect of the present invention, a comparison was made between the amount of power consumed in the case of ON-OFF control and the amount of power consumed in the case of automatic control. Eight ventilation fans (Kamakura Manufacturing RF-42ARN roof fans, rated 2.2 kW) were used, each equipped with an inverter (Mitsubishi Electric FR-D720-2.2K 10-pole), which was automatically controlled by one PLC (Mitsubishi Electric FX3U-16MR / ES) to achieve three levels of output, as shown in the flowchart in Figure 2. The fan blade rotation speed and power consumption at the three levels of output were 600 RPM and 2.2 kW at 50 Hz, 420 RPM and 0.755 kW at 35 Hz, and 300 RPM and 0.275 kW at 25 Hz, respectively. The total hours and amount of electricity used in the year from July 2022 to June 2023 at the factory where this automatic control device was installed was 5,165 hours and 35,332 kWh, with the breakdown of operating hours being 1,332 hours at 50Hz, 900 hours at 35Hz, and 2,933 hours at 25Hz. The remaining 3,595 hours of non-operating time was when the ventilation fan was completely turned off. In this case, the annual power consumption for simple ON-OFF control was estimated to be 90,904 kWh, assuming that the ventilation fan was operated at the rated speed of 50 Hz, 600 RPM, and 2.2 kw for a total of 5,165 hours of operation. As a result, in this example, the annual power consumption reduction effect was calculated to be 55,572 kWh, a difference between the 35,332 kWh annual power consumption when automatic control devices were installed on eight roof fans rated at 2.2 kw and the 90,904 kWh annual power consumption without automatic control. [Industrial Applicability]

[0016] By retrofitting a general-purpose PLC and inverter, this automatic control device can easily and inexpensively reduce the power consumption of ventilation fans used in large-volume facilities such as factories and warehouses.It can also be applied to traditional factories and warehouses, and its energy-saving effects are significant.

Claims

1. An automatic ventilation fan control device that automatically controls the rotation speed of the ventilation fan motor to adjust the exhaust volume of the ventilation fan to the minimum necessary in large-volume facilities according to the work situation and environmental conditions, thereby saving energy.

2. The automatic ventilation fan control device according to claim 1, wherein the information from the temperature measuring device and the rain sensor as the environmental conditions is processed by a general-purpose PLC control device, and the rotation speed of the multiple ventilation fans is controlled by an associated inverter.

3. 3. The automatic ventilation fan control device according to claim 2, further comprising a humidity measuring device added to the environmental conditions, and automatically controlling the rotation speed of the ventilation fan so as to appropriately adjust the exhaust volume of the ventilation fan based on the heat index (WBGT).

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