JP7708641B2 - air conditioner - Google Patents

Description

This disclosure relates to an air conditioner that controls room temperature.

For example, the air conditioning device described in Patent Document 1 increases the airflow (air speed) to raise the temperature of the supply air returning to the indoor heat exchanger, thereby minimizing the operating time until the thermostat is turned off while suppressing changes in the temperature in the server room.

Patent No. 4439419

In the invention described in Patent Document 1, the amount of air blown is increased in order to extend the operating time until the thermostat is turned off as much as possible, which may result in increased power consumption by the blower.

In view of the above, the present disclosure discloses an example of an air conditioner that can suppress an increase in the power consumption of a blower.

It is desirable for an air conditioner that controls room temperature to have at least one of the following components, for example. That is, the components include a heat exchanger (5) that uses cold energy generated by a vapor compression refrigerator having a compressor (2) to cool the air to be supplied to the room, and a blower (5A) that generates an air flow that passes through the heat exchanger (5) and is supplied to the room, the blower (5A) having a fan (5B) and an electric motor (5C) that rotates the fan, an intake side temperature sensor (7A) that detects the temperature of the air before it is heat exchanged in the heat exchanger, a blowing side temperature sensor (7B) that detects the temperature of the air after it has been heat exchanged in the heat exchanger, and the detection temperature (hereinafter referred to as the measured temperature) of the intake side temperature sensor (7A) is predetermined. The system includes a capacity control unit (6) that controls the rotation speed of the compressor (2) so that the suction temperature is set, and stops the compressor (2) when a predetermined condition (hereinafter referred to as a stop condition) is satisfied for a predetermined period of time, and a fan control unit (6) that controls the rotation speed of the electric motor (5C) (hereinafter referred to as the fan rotation speed), and is capable of executing normal control or stop extension control. In the stop extension control, the control is executed when the stop condition is satisfied, and the fan rotation speed is smaller than the fan rotation speed immediately before the stop extension control is started.

The stop condition refers to a state in which the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as the thermo-off threshold) and the rotation speed of the compressor (2) is equal to or lower than a predetermined rotation speed. In normal control, the fan rotation speed is controlled so that the temperature detected by the blow-out side temperature sensor (7B) becomes equal to the predetermined blow-out set temperature.

This makes it possible for the air conditioner to prevent an increase in the power consumption of the blower and to prevent large fluctuations in room temperature.

Incidentally, the symbols in parentheses above are examples showing the corresponding relationship with the specific configurations etc. described in the embodiments described below, and the present disclosure is not limited to the specific configurations etc. shown by the symbols in parentheses above.

1 is a diagram showing an air conditioning device according to a first embodiment; 5 is a flowchart showing control of a second fan according to the first embodiment. 4 is an operation explanatory chart of the air conditioner according to the first embodiment. 10 is an explanatory chart of the operation of an air conditioner according to a second embodiment. 13 is a flowchart showing control of a second fan according to the third embodiment.

The following "embodiment of the invention" shows an example of an embodiment that falls within the technical scope of this disclosure. In other words, the invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the embodiment below.

At least one of each of the components or parts described with a reference number is provided, unless otherwise specified by "one". In other words, unless otherwise specified by "one", two or more of the components may be provided. The air conditioner shown in this disclosure includes at least the components described with a reference number, as well as the structural elements shown in the drawings.

First Embodiment
<1. Overview of air conditioning equipment>
In this embodiment, an example of an air conditioning device according to the present disclosure is applied to an air conditioning device that provides air conditioning in a server room such as a data center or a communication equipment room, etc. The air conditioning device is a so-called "package air conditioner" that is configured with a vapor compression type refrigerator.

The air conditioner 1 shown in FIG. 1 generates cold or hot heat (cold heat in this embodiment) to condition the interior of a server room. The air conditioner 1 includes a compressor 2, a condenser 3, an expansion valve 4, an evaporator 5, a control unit 6, a first temperature sensor 7A to a fourth temperature sensor 7D, a first pressure sensor 7E, etc.

The compressor 2 compresses low-pressure gas-phase refrigerant and supplies it to the condenser 3. The compressor 2 is driven by an electric motor (not shown). The electric motor is driven by an inverter-type drive circuit (not shown). The operation of the drive circuit is controlled by the control unit 6.

That is, the drive circuit supplies a drive current to the electric motor and can change the frequency of the drive current (hereinafter referred to as the drive frequency). The drive circuit supplies the electric motor with a drive current having a drive frequency according to a command frequency from the control unit 6. In other words, the operation of the compressor 2 is controlled by the control unit 6 via the drive circuit.

The condenser 3 is a high-pressure side heat exchanger that cools the high-pressure refrigerant compressed by the compressor 2. In the condenser 3, the gas phase refrigerant is cooled and liquefied (condensed). The expansion valve 4 reduces the pressure and expands the high-pressure refrigerant flowing out from the condenser 3, and supplies it to the evaporator 5.

The evaporator 5 evaporates the low-pressure liquid refrigerant to generate cold heat. The first fan 3A blows cooling air to the condenser 3. The second fan 5A generates an airflow that passes through the evaporator 5 and is supplied to the server room.

Specifically, the second blower 5A draws in air from within the server room and supplies it to the evaporator 5, and also supplies the air cooled by the evaporator 5 to the server room. The second blower 5A is configured with a fan 5B and an electric motor 5C that rotates the fan 5B.

The control unit 6 controls at least the opening degree of the compressor 2, the second blower 5A, and the expansion valve 4. That is, the control unit 6 constitutes a capacity control unit that controls the rotation speed of the compressor 2, and a fan control unit that controls the rotation speed of the second blower 5A, i.e., the electric motor 5C (hereinafter referred to as the fan rotation speed).

The control unit 6 is configured with a microcomputer having a CPU, ROM, RAM, etc. The capacity control unit and fan control unit are realized by the CPU executing software stored in a non-volatile storage unit such as the ROM.

The control unit 6 receives detection signals from the first temperature sensor 7A to the fourth temperature sensor 7D and the first pressure sensor 7E. The first temperature sensor 7A detects the temperature of the air before it is cooled by the evaporator 5.

The second temperature sensor 7B detects the temperature of the air after it has been cooled by the evaporator 5. The third temperature sensor 7C detects the refrigerant temperature at the refrigerant outlet of the evaporator 5. The fourth temperature sensor 7D detects the refrigerant temperature at the refrigerant inlet of the evaporator 5. The first pressure sensor 7E detects the refrigerant pressure inside the evaporator 5.

2. Overview of control
<Expansion valve control>
The control unit 6 controls the opening degree of the expansion valve 4 so that the degree of superheat of the refrigerant at the refrigerant outlet of the evaporator 5 becomes a predetermined degree of superheat. The control unit 6 grasps the temperature difference between the temperature detected by the third temperature sensor 7C and the evaporation temperature calculated from the pressure detected by the first pressure sensor 7E as the degree of superheat.

<Compressor control>
The capacity control section, i.e., the control section 6, can control the compressor 2 by suction priority control or refrigeration off control. The suction priority control is a control for adjusting the refrigeration capacity generated by the evaporator 5. The refrigeration off control is a control for stopping the compressor 2.

<Suction priority control>
In suction priority control, the control unit 6 controls the rotation speed of the compressor 2 so that the temperature detected by the first temperature sensor 7A (hereinafter, in this embodiment, referred to as the measured temperature) becomes a predetermined temperature (hereinafter, referred to as the suction set temperature).

Specifically, if the measured temperature is higher than the suction set temperature, the control unit 6 increases the rotation speed of the compressor 2. If the measured temperature is lower than the suction set temperature, the control unit 6 decreases the rotation speed of the compressor 2.

<Thermo-off control>
In the thermo-off control, the control unit 6 stops the compressor 2 when a state in which a predetermined condition (hereinafter referred to as a stop condition) is satisfied exceeds a predetermined time. The stop condition refers to a state in which the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as a thermo-off threshold) and the rotation speed of the compressor 2 is equal to or lower than a predetermined rotation speed.

The control unit 6 according to this embodiment uses the drive frequency to grasp the "rotation speed of the compressor 2." Therefore, the control unit 6 stops the compressor 2 when the measured temperature drops below the thermo-off threshold and the drive frequency remains below the frequency corresponding to the above rotation speed (hereinafter referred to as the minimum frequency) for a predetermined period of time.

<Control of the second fan>
The fan control unit, i.e., the control unit 6, can control the second blower 5A in normal control or extended stop control. The normal control is executed at least when the suction priority control is executed. The capacity control unit and the fan control unit operate independently and in parallel with each other.

<Normal control>
The control unit 6 controls the air volume of the second blower 5A so that the temperature detected by the second temperature sensor 7B (hereinafter referred to as the blowing temperature) becomes a preset temperature (hereinafter referred to as the blowing/suction setting temperature).

That is, the electric motor 5C is driven by an inverter-type drive circuit (not shown), similar to the compressor 2. The operation of the drive circuit is controlled by the control unit 6. The drive circuit supplies the electric motor 5C with a drive current having a drive frequency corresponding to a command frequency (hereinafter also referred to as command rotation speed Cr) from the control unit 6.

The control unit 6 reduces the commanded rotation speed when the blowing temperature is higher than the blowing/suction set temperature, and increases the commanded rotation speed when the blowing temperature is lower than the blowing/suction set temperature. The blowing/suction set temperature is a temperature obtained by adding a predetermined value to the suction set temperature.

<Stop extension control>
The stop extension control is executed when the stop condition is satisfied, that is, when the measured temperature is equal to or lower than the thermo-off threshold and the drive frequency is equal to or lower than the frequency. When the stop extension control is executed, at least at the start, the second blower 5A has a fan rotation speed that is smaller than the fan rotation speed immediately before the stop extension control is started.

Specifically, in the stop extension control, the fan rotation speed is controlled so that the measured suction temperature becomes a predetermined temperature (hereinafter referred to as the extension threshold) that is higher than the thermo-off threshold. In other words, the control unit 6 controls the command rotation speed Cr so that the measured temperature becomes the extension threshold.

The stop extension control controls the command rotation speed Cr so that the measured temperature becomes a predetermined temperature that is greater than the extension threshold, i.e., the thermo-off threshold, so that for at least a predetermined time from when the stop extension control is started, the fan rotation speed is smaller than the fan rotation speed immediately before the stop extension control is started.

For this reason, if the amount of heat generated in the server room (hereinafter referred to as the thermal load) fluctuates from the time the stop extension control is started, the control unit 6 may set the fan rotation speed to a higher value than the fan rotation speed immediately before the stop extension control is started in order to maintain the measured temperature at the extension threshold.

In other words, the stop extension control has a first stop extension control period during which the fan rotation speed is smaller than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period following the first stop extension control period, that is, a period during which the fan rotation speed changes depending on the measured temperature.

<Details of Control of Second Fan (see FIG. 2)>
2 is executed simultaneously with the start-up of the air conditioner 1 and is stopped simultaneously with the stop of the air conditioner 1. When this control is started, the control unit 6 executes normal control (S1).

Next, the control unit 6 determines whether the stop condition is met (S2). If the stop condition is met (S2: YES), the control unit 6 executes the stop extension control (S3). If the stop condition is not met (S2: NO), the control unit 6 continues normal control (S1).

When the stop extension control is executed, the control unit 6 determines whether the drive frequency of the compressor 2 is equal to or lower than the minimum frequency (S4). If the drive frequency is equal to or lower than the minimum frequency (S4: YES), the control unit 6 continues the stop extension control (S3). If the drive frequency is higher than the minimum frequency (S4: NO), the control unit 6 stops the stop extension control and executes normal control (S1).

3. Features of the Air Conditioner According to the Present Embodiment (See FIG. 3)
In normal control, when the cooling load is small and the rotation speed of the compressor 2 falls below the minimum frequency, the suction temperature, which is the measured temperature, falls below the thermo-off threshold (see A in FIG. 3). As a result, the stop condition is met, and the air conditioner 1 transitions from normal control to stop extension control (see B in FIG. 3).

When control transitions to extended stop control, the command rotation speed Cr is controlled so that the measured temperature, the suction temperature, becomes the extended threshold value. As a result, when the thermal load increases, the command rotation speed Cr, i.e., the fan rotation speed, increases, and the measured temperature is maintained above the thermo-off threshold value (see C in Figure 3).

Then, when the thermal load increases and the commanded rotation speed Cr, i.e., the fan rotation speed, reaches a predetermined upper limit rotation speed and the suction temperature (measured temperature) rises (see D in Figure 3), the rotation speed of the compressor 2 increases, and normal control is restored (see E in Figure 3).

As a result, in this embodiment, it is possible to suppress an increase in power consumption of the second blower 5A, and the compressor 2 can be prevented from stopping (thermo-off), so that changes in temperature in the server room can be suppressed.

Second Embodiment
The following description will focus on the differences between this embodiment and the first embodiment, and any description that overlaps with the first embodiment will be omitted.

1. Overview of air conditioner control
In the air conditioner according to this embodiment, blow-out priority control or thermo-off control is executed as the rotation speed control of the compressor 2. That is, in this embodiment, blow-out priority control is executed instead of suction priority control.

<Compressor control>
In the blow-out priority control, the rotation speed of the compressor 2 is controlled so that the temperature detected by the second temperature sensor 7B, i.e., the blow-out temperature (hereinafter referred to as the measured temperature in this embodiment), becomes a predetermined blow-out set temperature.

The thermo-off control is the same as that of the air conditioner 1 according to the first embodiment. However, in this embodiment, the blowing temperature is used as the measured temperature, and therefore at least the specific value of the thermo-off threshold is different from the specific value of the thermo-off threshold according to the first embodiment.

<Control of the second fan>
In the air conditioner according to this embodiment, normal control or extended stop control is executed as the rotation speed control of the second fan 5A. In the normal control according to this embodiment (hereinafter, abbreviated as normal control), the fan rotation speed is controlled in conjunction with the drive frequency, which is the command signal value of the capacity control unit.

In other words, in normal control, the command rotation speed Cr, which is the fan rotation speed, is determined as a function value of the rotation speed of the compressor 2. Therefore, when the rotation speed of the compressor 2 increases, the command rotation speed Cr increases accordingly, and when the rotation speed of the compressor 2 decreases, the command rotation speed Cr decreases accordingly.

The stop extension control according to this embodiment (hereinafter, abbreviated as stop extension control) is also executed when the stop condition is satisfied, similar to the first embodiment. In the stop extension control, the command rotation speed Cr is controlled so that the measured temperature, which is the blowing temperature, becomes the extension threshold value according to this embodiment (hereinafter, abbreviated as extension threshold value).

For this reason, in this embodiment, the fan rotation speed is higher than the fan rotation speed immediately before the stop extension control is started, at least for a predetermined time from when the stop extension control is started.

In addition, since the control unit 6 maintains the measured temperature at the extension threshold, if the heat load generated in the server room fluctuates from the time the stop extension control is started, the fan rotation speed may become smaller than the fan rotation speed immediately before the stop extension control is started.

In other words, the stop extension control has a first stop extension control period during which the fan rotation speed is higher than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period following the first stop extension control period, that is, a period during which the fan rotation speed changes depending on the measured temperature.

The control flow of the second blower 5A according to this embodiment is the same as the control flow of the second blower 5A according to the first embodiment. Therefore, a description of the control flow of the second blower 5A according to this embodiment is omitted.

2. Features of the Air Conditioner According to the Present Embodiment (See FIG. 4)
In normal control, when the cooling load is small and the rotation speed of the compressor 2 becomes the minimum frequency, the blowout set temperature, which is the measured temperature, becomes equal to or lower than the thermo-off threshold value (see A in FIG. 4). As a result, the stop condition is met, and the air conditioner 1 transitions from normal control to stop extension control.

When control transitions to stop extension control, the command rotation speed Cr is controlled so that the measured temperature, that is, the blowing temperature, becomes the extension threshold value, so the command rotation speed Cr, i.e., the fan rotation speed, increases and the measured temperature is maintained above the thermo-off threshold value (see B in Figure 4).

At this time, if the thermal load increases, the control unit 6 maintains the measured temperature at the extended threshold by reducing the rotation speed of the second fan 5A (see C in FIG. 4). Then, when the rotation speed of the second fan 5A reaches a predetermined lower limit rotation speed, the blowing temperature increases with the increase in thermal load (see D in FIG. 4), and the rotation speed of the compressor 2 increases, so that normal control is restored (see E in FIG. 4).

Third Embodiment
This embodiment is a modified example of the air conditioner according to the second embodiment. The following description will focus on the differences between this embodiment and the second embodiment. Descriptions that overlap with the second embodiment will be omitted.

In other words, in the first and second embodiments, after switching from normal control to stop extension control, the control is configured to return to normal control when the heat load increases and the drive frequency of the compressor 2 becomes higher than the minimum frequency.

In contrast, in this embodiment, after switching from normal control to stop extension control, normal control is restored when the current fan rotation speed (command rotation speed Cr) becomes equal to or lower than the fan rotation speed (hereinafter referred to as the compressor-linked command rotation speed) determined as a function value of the rotation speed of compressor 2 (in this embodiment, the drive frequency).

Note that FIG. 5 shows the control of the second blower according to this embodiment. The control shown in FIG. 5 is executed simultaneously with the start-up of the air conditioner 1, and is stopped simultaneously with the stop of the air conditioner 1. When this control is started, the control unit 6 executes normal control (S11).

Next, the control unit 6 determines whether the stop condition is met (S12). If the stop condition is met (S12: YES), the control unit 6 executes the stop extension control (S13). If the stop condition is not met (S12: NO), the control unit 6 continues normal control (S11).

When the stop extension control is executed, the control unit 6 determines whether the current fan rotation speed (command rotation speed Cr) is greater than the compressor interlock command rotation speed (S14).

If the current command speed Cr is greater than the compressor-linked command speed (S14: YES), the control unit 6 continues the stop extension control (S13). If the current command speed Cr is equal to or less than the compressor-linked command speed (S14: NO), the control unit 6 stops the stop extension control and executes normal control (S11).

As a result, in this embodiment, the release of the stop extension control is determined based on the instruction value of normal control. Therefore, it is possible to prevent the rotation speed of the second blower 5A, which was increased by the stop extension control, from suddenly decreasing, and the blowing temperature from becoming extremely low.

Other Embodiments
In the above embodiment, the air conditioner according to the present disclosure is applied to a cooling operation. However, the present disclosure is not limited thereto. That is, the present disclosure is applicable to, for example, the air conditioner according to the present disclosure in a heating operation.

When the present disclosure is applied to heating operation, the target heat exchanger is the condenser 3, and the target blower is the first blower 3A. When the air conditioner according to the first embodiment is applied to heating operation, "the stop extension control is performed at a fan speed that is higher than the fan speed immediately before the stop extension control is started." When the air conditioner according to the second embodiment is applied to heating operation, "the stop extension control is performed at a fan speed that is lower than the fan speed immediately before the stop extension control is started."

In the above embodiment, the fan speed was controlled so that the measured temperature reached the extension threshold value from the time the stop extension control was started, resulting in the first stop extension control period. However, the present disclosure is not limited to this.

In other words, if the period from when the stop extension control is started until a predetermined time has elapsed is defined as the first stop extension control period, in the case of blowing priority control, the second blower 5A may be operated at a rotation speed that is a predetermined increase from the fan rotation speed immediately before the stop extension control is started.

In addition, in the case of suction priority control, during the first stop extension control period, the second blower 5A may be operated at a rotation speed that is the fan rotation speed immediately before the stop extension control is started minus a predetermined rotation speed.

Furthermore, the present disclosure is not limited to the above-mentioned embodiments as long as it conforms to the spirit of the disclosure described in the above-mentioned embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-mentioned embodiments are combined, or a configuration in which any of the constituent elements illustrated or the constituent elements described with reference numerals in the above-mentioned embodiments are eliminated.

Reference Signs List 1: Air conditioner 2: Compressor 3: Condenser 3A: First fan 4: Expansion valve 5: Evaporator 5A: Second fan 6: Control unit

Claims (4)

In an air conditioning device that controls room temperature,
a heat exchanger that uses cold heat generated by a vapor compression refrigeration machine having a compressor to cool air to be supplied to a room;
a blower that generates an airflow that passes through the heat exchanger and is supplied to a room, the blower having a fan and an electric motor that rotates the fan;
a suction side temperature sensor that detects the temperature of the air before it is heat exchanged in the heat exchanger;
a blow-out side temperature sensor that detects the temperature of the air after heat exchange in the heat exchanger;
a capacity control unit that controls the number of revolutions of the compressor so that the temperature detected by the suction side temperature sensor (hereinafter referred to as the measured temperature) becomes a predetermined suction set temperature, and that stops the compressor when a predetermined condition (hereinafter referred to as the stop condition) is satisfied for a predetermined time period;
a fan control unit that controls a rotation speed of the electric motor (hereinafter referred to as a fan rotation speed) and is capable of executing normal control or stop extension control;
The stop condition is a state in which the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as a thermo-off threshold) and the rotation speed of the compressor is equal to or lower than a predetermined rotation speed,
In the normal control, the fan rotation speed is controlled so that the detected temperature of the blow-out side temperature sensor becomes a predetermined blow-out set temperature,
Furthermore, the stop extension control is an air conditioning control that is executed when the stop condition is satisfied, and that includes a first stop extension control period in which the fan rotation speed is smaller than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period after the first stop extension control period in which the fan rotation speed changes according to the measured temperature . In an air conditioning device that controls room temperature,
a heat exchanger that uses cold heat generated by a vapor compression refrigeration machine having a compressor to cool air to be supplied to a room;
a blower that generates an airflow that passes through the heat exchanger and is supplied to a room, the blower having a fan and an electric motor that rotates the fan;
a blow-out side temperature sensor that detects the temperature of the air after heat exchange in the heat exchanger;
a capacity control unit that controls the number of revolutions of the compressor so that the temperature detected by the blow-out side temperature sensor (hereinafter referred to as the measured temperature) becomes a predetermined blow-out set temperature, and that stops the compressor when a predetermined condition (hereinafter referred to as the stop condition) is satisfied for a predetermined time period;
a fan control unit that controls a rotation speed of the electric motor (hereinafter referred to as a fan rotation speed) and is capable of executing normal control or stop extension control;
The stop condition is a state in which the measured temperature is equal to or lower than a predetermined temperature (hereinafter referred to as a thermo-off threshold) and the rotation speed of the compressor is equal to or lower than a predetermined rotation speed,
In the normal control, the fan rotation speed is controlled to a value determined as a function value of the command signal value of the capacity control unit,
Furthermore, the air conditioning device is one in which the stop extension control is executed when the stop condition is satisfied, and which includes a first stop extension control period in which the fan rotation speed is higher than the fan rotation speed immediately before the stop extension control is started, and a second stop extension control period after the first stop extension control period, in which the fan rotation speed changes depending on the measured temperature . The air conditioner according to claim 2, wherein the fan control unit returns control of the blower to the normal control when the current fan speed becomes equal to or lower than a value determined as a function value of the command signal value of the capacity control unit during execution of the stop extension control. An air conditioner according to any one of claims 1 to 3, wherein in the stop extension control, the fan speed is controlled so that the measured temperature becomes a predetermined temperature that is greater than the thermo-off threshold.