Air conditioner

Abstract

To disclose one example of an air conditioner that solves the problem that in an air conditioner with a low thermo-off temperature, a compressor continues to operate even when a temperature is lower than an original thermo-off temperature, which may result in a room being overcooled.SOLUTION: When a thermo-off condition is satisfied, that is, if a rate of change of a measured temperature is negative when a determination period has elapsed since start of determination, a control unit 10 stops a compressor 4, and if the rate of change of the measured temperature is zero or positive when the determination period has elapsed, the control unit continues to operate the compressor 4 even after the determination period has elapsed. This prevents the compressor 4 from being stopped, which prevents the stop and start of the compressor 4 from being repeated frequently and can suppress the generation of overcooling in a room.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an air conditioner having at least a cooling function. [Background technology]

[0002] In a typical air conditioner, to prevent the room from being overcooled, the compressor is stopped and cooling of the air is stopped when the room temperature falls below a predetermined temperature (hereinafter referred to as the thermo-off temperature).

[0003] However, when the compressor is stopped, the air it has drawn in is blown out directly into the room, causing the air temperature to rise quickly, making it easier for the compressor to restart. This can lead to frequent cycles of stopping and starting the compressor.

[0004] In response to this, for example, in the air conditioning device described in Patent Document 1, when predetermined conditions are met, the thermo-off temperature is lowered to prevent the compressor from being stopped and started frequently. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4439419 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the air conditioner described in Patent Document 1, the thermo-off temperature is lowered, so the compressor continues to operate even when the temperature is lower than the intended thermo-off temperature, which may result in the room being overcooled. The present disclosure discloses an example of an air conditioner that takes this into consideration. [Means for solving the problem]

[0007] It is desirable that the air conditioner have at least one of the following components: a heat exchanger (2) that uses cold energy generated by a vapor compression refrigerator to cool air to be supplied to a room, a temperature sensor (S1) that detects the temperature of the room air, and a control unit (10) that controls the rotation speed of a compressor of the vapor compression refrigerator using the temperature detected by the temperature sensor (S1) (hereinafter referred to as the measured temperature) and a target room air temperature (hereinafter referred to as the set temperature), and the control unit (10) is capable of stopping the compressor if the rate of change of the measured temperature is negative when a determination period has elapsed.

[0008] The temperature obtained by subtracting a predetermined value from the set temperature is defined as the thermo-off temperature, and the judgment start time is when the actual measured temperature becomes equal to or lower than the thermo-off temperature and the compressor rotation speed becomes equal to or lower than a predetermined lower limit rotation speed.The time from the judgment start time until the predetermined time has elapsed is called the judgment period.

[0009] As a result, in the air conditioner, the compressor is prevented from being stopped and started frequently and the occurrence of excessive cooling in the room can be suppressed. Incidentally, the symbols in each of the parentheses above are examples showing the correspondence 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 the parentheses above. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a vapor compression refrigerator. [Figure 2] FIG. 2 is an explanatory diagram showing the operational characteristics of the air conditioner according to the first embodiment. [Figure 3] 3 is a flowchart showing the operation of the air conditioner according to the first embodiment. [Figure 4] FIG. 6 is an explanatory diagram showing the operational characteristics of the air conditioner according to the second embodiment. [Figure 5] 10 is a flowchart showing the operation of an air conditioner according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following "embodiments of the invention" are examples of embodiments that fall within the technical scope of the present disclosure. In other words, the invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

[0012] At least one of a component or part that is described with a reference numeral is provided unless otherwise specified, such as "one." The air conditioning device shown in this disclosure includes at least one of the components such as the component or part that is described with a reference numeral and the structural parts shown in the drawings.

[0013] (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 for a server room. Heat-generating elements such as information communication devices are installed in the server room. The air conditioning device cools the air in the server room (hereinafter abbreviated as the room) to maintain the air temperature in the room within a predetermined range.

[0014] An air conditioner uses cold energy generated by a vapor compression refrigerator to cool the air to be supplied to a room. Specifically, as shown in Fig. 1, the vapor compression refrigerator 1 is configured with an indoor heat exchanger 2, an outdoor heat exchanger 3, a compressor 4, a pressure reducer 5, etc.

[0015] The compressor 4 compresses the gas phase refrigerant and discharges it to the outdoor heat exchanger 3. The outdoor heat exchanger 3 is a radiator that cools the high-pressure refrigerant. The pressure reducer 5 reduces the pressure of the high-pressure refrigerant that flows out from the outdoor heat exchanger 3. The indoor heat exchanger 2 cools the air to be supplied indoors by using the latent heat of evaporation when heat is exchanged between the reduced-pressure liquid phase refrigerant and the air.

[0016] The air conditioner also includes a control unit 10 and a temperature sensor S1. The temperature sensor S1 detects the temperature of the indoor air. The control unit 10 controls the rotation speed of the compressor 4 and the like using the temperature detected by the temperature sensor S1 (hereinafter referred to as the measured temperature) and a target indoor air temperature (hereinafter referred to as the set temperature).

[0017] Specifically, for example, when the measured temperature is on an upward trend toward the set temperature, the control unit 10 increases the rotation speed of the compressor 4 to increase the cooling capacity generated in the indoor heat exchanger 2. When the measured temperature is on a downward trend toward the set temperature, the control unit 10 decreases the rotation speed of the compressor 4 to decrease the cooling capacity generated in the indoor heat exchanger 2.

[0018] In this embodiment, the degree of pressure reduction of the pressure reducer 5, i.e., the throttle opening, is also controlled by the control unit 10. The control unit 10 controls the throttle opening in conjunction with the rotation speed of the compressor 4 according to a predetermined rule.

[0019] <2. Thermo-off control / thermo-on control> Thermo-off control is a control that stops the compressor 4 and stops cooling by the indoor heat exchanger 2 in order to prevent the room from being overcooled. Thermo-on control is a control that restarts the compressor 4 that has been stopped by thermo-off control or a control that continues the operation of the compressor 4.

[0020] <Definition of terms (see Figure 2)> The thermo-off temperature is the temperature obtained by subtracting a predetermined value (for example, 1°C) from the set temperature. The start of judgment is the time when the measured temperature falls below the thermo-off temperature and the rotation speed of the compressor 4 falls below a predetermined lower limit rotation speed. The judgment period is the time from the start of judgment until a predetermined time (for example, 5 minutes) has elapsed.

[0021] The thermo-off condition is met when the measured temperature is equal to or lower than the thermo-off temperature and the rotation speed of the compressor 4 is equal to or lower than a predetermined lower limit rotation speed. The time when it is determined that the thermo-off condition is met is the start time of the judgment.

[0022] <Compressor start / stop control> When the thermo-off condition is satisfied, that is, when the determination period has elapsed since the start of the determination and the rate of change in the measured temperature is negative, the control unit 10 stops the compressor 4 (see FIG. 2). Also, when the rate of change in the measured temperature is 0 or positive when the determination period has elapsed, the control unit 10 continues to operate the compressor 4 even after the determination period has elapsed.

[0023] It is desirable to determine the rate of change using the most recent measured temperature either before or after the determination period has elapsed. In other words, the rate of change is determined using data that appropriately indicates the trend of change in the measured temperature at the time the determination period has elapsed.

[0024] 3 is a flowchart showing the on / off control. This control is always active while the air conditioner is in operation. That is, the control unit 10 first determines whether or not the thermo-off condition is met (S1).

[0025] If the thermo-off condition is not met (S1: NO), this control is executed again from S1. If it is determined that the thermo-off condition is met (S1: YES), timing of the determination period is started, and it is determined whether the determination period (5 minutes in this embodiment) has elapsed (S2).

[0026] When the determination period has elapsed (S2: YES), the control unit 10 determines whether the rate of change of the measured temperature is 0 or positive when the determination period has elapsed (S3). If the rate of change of the measured temperature is 0 or positive (S3: YES), the control unit 10 continues to operate the compressor 4 (S4).

[0027] If the rate of change of the measured temperature is negative when the determination period has elapsed (S3: NO), the control unit 10 executes thermo-off control (stopping the compressor 4) (S5). When the thermo-off control ends and the compressor 4 is started (thermo-on control is executed), the control unit 10 executes start-up control to start the compressor 4 at its upper limit rotation speed, as shown in FIG.

[0028] Then, the control unit 10 executes the startup control until a predetermined time has elapsed since the rotation speed of the compressor 4 reached the upper limit rotation speed. After the time has elapsed, the control unit 10 executes temperature control, which controls the rotation speed of the compressor 4 in accordance with the measured temperature.

[0029] After the start of the determination, even before the determination period has elapsed, if the measured temperature is equal to or higher than the thermo-off temperature or the rotation speed of the compressor 4 is higher than the lower limit rotation speed, the control unit 10 executes temperature control.

[0030] After the control unit 10 continues to operate the compressor 4 in S4, it executes S1 again. If it is determined that the thermo-off condition is met (S1: YES), the control unit 10 starts timing a determination period and determines whether the determination period (5 minutes in this embodiment) has elapsed (S2).

[0031] The determination time of S2 after S4 is executed is equivalent to the case where the compressor 4 is operated for an extended period of time from the time when the determination period has elapsed until a predetermined time has elapsed. In other words, the "determination time of S2 after S4 is executed" is essentially an "extended time."

[0032] Therefore, in this embodiment, if the rate of change of the actual measured temperature when the extension time has elapsed is negative, the compressor 4 is stopped, and if the rate of change of the actual measured temperature when the extension time has elapsed is 0 or positive, the compressor 4 is allowed to continue operating.

[0033] 3. Features of the Air Conditioner According to the Present Embodiment In the air conditioning system according to this embodiment, as described above, stopping of the compressor 4 is suppressed, so that frequent stopping and starting of the compressor 4 is suppressed, and the occurrence of supercooling in the room can be suppressed.

[0034] (Second embodiment) As shown in Figure 4, if the rate of change of the actual measured temperature is positive when the judgment period has elapsed, the control unit 10 of this embodiment executes an extended control mode in which the compressor continues to operate from the time the judgment period has elapsed until a predetermined time (hereinafter referred to as the extension time) has elapsed.

[0035] Then, the control unit 10 stops the compressor if (a) the thermo-off condition is met when the extension time has elapsed and the met state continues for a determination time (5 minutes in this embodiment).

[0036] Furthermore, if the rate of change in the measured temperature after the extension time has elapsed is 0 or positive, the control unit 10 continues to operate the compressor. Note that, when the extension control mode is being executed, if the measured temperature is equal to or higher than the thermo-off temperature or the rotation speed of the compressor 4 is higher than the lower limit rotation speed, the control unit 10 executes temperature control.

[0037] 5 is a flowchart showing the on / off control. That is, the control unit 10 first determines whether or not the thermo-off condition is met (S1). If the thermo-off condition is not met (S1: NO), this control is executed again from S1.

[0038] If it is determined that the thermo-off condition is met (S1: YES), timing of the determination period begins, and it is determined whether the determination period has elapsed (S2). Note that the "determination time of S2 after the compressor 4 continues to operate (S4)" is essentially the "extension time."

[0039] When the determination period has elapsed (S2: YES), the control unit 10 determines whether the rate of change of the measured temperature is 0 or positive when the determination period has elapsed (S3). If the rate of change of the measured temperature is negative (S3: NO), the control unit 10 executes thermo-off control (stopping the compressor 4) (S5).

[0040] If the rate of change of the measured temperature is 0 or positive (S3: YES), the control unit 10 continues to operate the compressor 4 (S4). After continuing to operate the compressor 4 (S4), the control unit 10 again determines whether the thermo-off condition is met (S6).

[0041] If the thermo-off condition is not satisfied (S6: NO), S1 is executed again. If the thermo-off condition is satisfied (S6: YES), the control unit 10 determines whether the duration during which the thermo-off condition is satisfied has exceeded the determination time (S7).

[0042] If the duration that satisfies the thermo-off condition is less than the determination time (S7: NO), S6 is executed again. If the duration that satisfies the thermo-off condition is equal to or greater than the determination time (S7: YES), the control unit 10 stops the compressor 4 (S5).

[0043] (Third embodiment) The control unit 10 according to this embodiment can execute control to reset the set temperature to a temperature lower than the current set temperature at a predetermined timing during the determination period.

[0044] Specifically, for example, if the determination period is five minutes, and the rate of change in the measured temperature is positive four minutes after the start of the determination period, the set temperature is set to the measured temperature at that time (four minutes after the start of the determination period). Then, when the determination period ends, the control unit 10 returns the set temperature to the original set temperature, i.e., the set temperature before the reset.

[0045] In other words, this control resets the set temperature to a temperature lower than the current set temperature at a predetermined timing during the judgment period, and returns the set temperature to the temperature before resetting at the end of the judgment period.

[0046] (Other embodiments) In the above-described embodiment, the present disclosure is applied to an air conditioner that cools a server room. However, the present disclosure is not limited to this. That is, the present disclosure may also be applied to an air conditioner that heats a room, for example.

[0047] In the above-described embodiment, if the rate of change of the measured temperature is positive when the determination period has elapsed, the operating time of the compressor 4 is extended even if the thermo-off condition is satisfied. However, the present disclosure is not limited to this.

[0048] In other words, the disclosure may, for example, relax the thermo-off condition by lowering the thermo-off temperature or lowering the lower limit rotation speed of compressor 4 when the rate of change of the actual measured temperature is positive when the judgment period has elapsed.

[0049] In the above-described embodiment, the compressor 4 continues to operate when the rate of change of the measured temperature is 0 or positive, and the compressor 4 is stopped when the rate of change of the measured temperature is negative. However, the present disclosure is not limited to this.

[0050] That is, the disclosure may be configured, for example, to continue operating compressor 4 when the rate of change of the measured temperature is positive, and to stop compressor 4 when the rate of change of the measured temperature is 0 or negative.

[0051] In the above-described embodiment, the determination period is a fixed value. However, the present disclosure is not limited to this. That is, the present disclosure may be configured to change the end of the determination period depending on, for example, the rate of change of the measured temperature during the determination period.

[0052] That is, for example, after the start of the judgment, the rate of change of the measured temperature is successively calculated, and if the rate of change is positive, the end period is extended as the rate of change becomes larger, and if the rate of change is negative, the end period is extended as the absolute value of the rate of change becomes smaller.

[0053] In the above-described embodiment, when the measured temperature is on an upward trend toward the set temperature, the control unit 10 increases the rotation speed of the compressor 4, and when the measured temperature is on a downward trend relative to the set temperature, the control unit 10 decreases the rotation speed of the compressor 4. However, in this case, the disclosure may increase the rotation speed of the compressor 4 even when the measured temperature exceeds the set temperature, and decrease the rotation speed of the compressor 4 even when the measured temperature is below the set temperature, for example.

[0054] Furthermore, the present disclosure is not limited to the above-described embodiments as long as it conforms to the spirit of the disclosure described in the above-described embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-described embodiments are combined, or a configuration in which any of the components illustrated or described with reference numerals in the above-described embodiments is eliminated. [Explanation of symbols]

[0055] 1. Vapor compression refrigerator 2… Indoor heat exchanger 3… Outdoor heat exchanger 4... Compressor 5... Pressure reducer 10... Control section S1... Temperature sensor

Claims

1. a heat exchanger that uses the cold generated by the vapor compression refrigerator to cool the air to be supplied to the room; a temperature sensor for detecting the temperature of indoor air; a control unit that controls a rotation speed of a compressor of the vapor compression refrigeration machine using an actual temperature that is a temperature detected by the temperature sensor and a set temperature that is a target indoor air temperature, A temperature obtained by subtracting a predetermined value from the set temperature is defined as a thermo-off temperature, a time when the measured temperature becomes equal to or lower than the thermo-off temperature and the rotation speed of the compressor becomes equal to or lower than a predetermined lower limit rotation speed is defined as a start time of judgment, and a time from the start time of judgment until a predetermined time has elapsed is defined as a judgment period. The air conditioner, wherein the control unit is capable of stopping the compressor if the rate of change of the measured temperature is negative when the determination period has elapsed.

2. The air conditioning device according to claim 1 , wherein the control unit is capable of continuing to operate the compressor even after the determination period has elapsed if the rate of change of the measured temperature is positive when the determination period has elapsed.

3. 3. The air conditioning device according to claim 2, wherein the control unit continues to operate the compressor from the time the determination period has elapsed until a predetermined time (hereinafter referred to as an extension time) has elapsed if the rate of change of the measured temperature is positive when the determination period has elapsed, and is capable of stopping the compressor when the measured temperature has become equal to or lower than the thermo-off temperature and the compressor rotation speed has been equal to or lower than the lower limit rotation speed for a predetermined time when the extension time has elapsed.

4. 3. The air conditioning device according to claim 2, wherein the control unit is configured to continue operating the compressor from the time the determination period has elapsed until a predetermined time (hereinafter referred to as an extension time) has elapsed if the rate of change of the actual measured temperature is positive when the determination period has elapsed, and to stop the compressor if the rate of change of the actual measured temperature when the extension time has elapsed is negative.

5. 5. The air conditioner according to claim 3, wherein the control unit is capable of continuing to operate the compressor if the rate of change of the measured temperature when the extension time has elapsed is positive.

6. The air conditioner according to claim 1 , wherein the control unit is capable of performing control to reset the set temperature to a temperature lower than the current set temperature at a predetermined timing during the determination period.

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