JP7319115B2 - air conditioner - Google Patents

Description

The present invention relates to an air conditioner.

Patent Literature 1 discloses a compressor start-up sequence for starting a compressor in an air conditioner. Japanese Patent Laid-Open No. 2004-100001 discloses that when a start-up failure is detected at the time of start-up of a drive motor for a compressor, the start-up voltage is sequentially increased by a predetermined voltage to restart the compressor. Further, the compressor start-up sequence of Patent Document 1 causes the air conditioner to abnormally stop when the start-up failure reaches a predetermined number of times.

JP-A-10-267432

Normally, the compressor start-up sequence in an air conditioner is supposed to start the compressor while suppressing vibration and noise at start-up. You are also asked to perform a boot.

The compressor start-up sequence in Patent Document 1 increases the certainty of start-up by increasing the start-up voltage of the motor when restarting after the start-up failure when start-up failure occurs for some reason. It does not assume failure to start when the load on the compressor is large. Further, according to the study of the inventor of the present application, the method of increasing the starting voltage of the motor as in Patent Document 1 can be said to be the optimum method for increasing the certainty of starting when the load on the compressor is large. isn't it. For this reason, in the compressor start-up sequence in Patent Document 1, the compressor may not be started under conditions that are more severe for the compressor start-up.

For example, when an air conditioner that has been operating at a high outside temperature is stopped and restarted, that is, in a situation where both the outside temperature and the compressor temperature are high, the compressor will be in an abnormal overload state. , when the air conditioner is restarted, the protective action is activated and the compressor tends to fail to start. The startup sequence of Patent Literature 1 cannot handle such a situation, and there is a risk that the operation of the air conditioner will stop after repeated startup failures.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an air conditioner capable of reliably starting a compressor even when both the outside air temperature and the compressor temperature are high.

In order to solve the above problems, the air conditioner of the present invention includes a determination unit that determines whether or not the compressor is in an overloaded state at the start of operation, and a control unit that performs start-up control of the compressor. When the determination unit determines that the compressor is not in an overloaded state, the control unit starts the compressor in a first start sequence that is highly effective in suppressing vibration and noise during start-up. and if the determination unit determines that the compressor is in an overloaded state, the compressor is started in a second start-up sequence that enables reliable start-up of the compressor even in the overloaded state. It is characterized by

According to the above configuration, when it is determined that the compressor is in an overloaded state, the compressor is started by the second startup sequence that enables reliable startup of the compressor. Failure can be prevented and reliable start can be performed.

Further, in the above air conditioner, the first and second startup sequences include a period during which the motor drive current of the compressor is forcibly increased during startup, and the compressor rotation speed is increased to a desired rotation speed. In the second startup sequence, the timing of increasing the motor drive current may be shifted later than in the first startup sequence.

According to the above configuration, in the second start-up sequence, the timing of increasing the motor drive current is shifted later than in the first start-up sequence. The rotor of the drive motor can be accelerated. As a result, even in an overloaded state where both the outside air temperature and the compressor temperature are high, it is possible to prevent the compressor from failing to start and to start it reliably.

Further, in the above air conditioner, the first and second startup sequences are startup sequences for increasing the motor drive current at timing when the compressor rotational speed reaches a predetermined compressor rotational speed, and In the second startup sequence, the predetermined compressor rotation speed may be set to a higher compressor rotation speed than in the first startup sequence.

Further, in the above air conditioner, the determination unit determines that the compressor is in an overload state when the outside air temperature is higher than a first temperature threshold and the compressor temperature is higher than a second temperature threshold. It can be configured to

The air conditioner of the present invention can reliably start the compressor by starting the compressor in the second starting sequence even in an overload state where both the outside air temperature and the compressor temperature are high. It has such an effect.

1 is a schematic configuration diagram of an air conditioner according to Embodiment 1. FIG. 4 is a flow chart showing a compressor start-up sequence at the start of operation of the air conditioner according to Embodiment 1. FIG. 4 is a timing chart showing changes in motor drive current and compressor rotation speed in the first startup sequence; 9 is a timing chart showing changes in motor drive current and compressor rotation speed in a second startup sequence;

[Embodiment 1]
Embodiment 1 of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an air conditioner 10 according to Embodiment 1, and shows a refrigeration cycle applied in the air conditioner 10. As shown in FIG.

The air conditioner 10 includes an indoor unit (indoor unit) 100 and an outdoor unit (outdoor unit) 110 . An indoor heat exchanger 101 is provided on the indoor unit 100 side on the path of the refrigeration cycle (heat pump) in the air conditioner 10, and a compressor 111, an outdoor heat exchanger 112, and a four-way valve 113 are provided on the outdoor unit 110 side. and an expansion valve 114 are provided. In addition, the indoor unit 100 is provided with an indoor fan 102 for sending out the air heat-exchanged by the indoor heat exchanger 101 indoors, and the outdoor unit 110 is provided with an indoor fan 102 for sending air to the outdoor heat exchanger 112. outdoor fan 115 is provided.

The air conditioner 10 also includes a first temperature sensor 121 that detects the outside air temperature and a second temperature sensor 122 that detects the compressor temperature. The first temperature sensor 121 detects the intake air temperature of the outdoor heat exchanger 112 as the outside air temperature. Although detailed illustration is omitted in FIG. 1, in addition to the first temperature sensor 121 and the second temperature sensor 122, the air conditioner 10 detects the temperature of each part in the refrigeration cycle as necessary. A temperature sensor is provided as appropriate.

The four-way valve 113 switches the direction of refrigerant circulation according to the cooling/heating operation of the air conditioner 10 (FIG. 1 shows the state during the cooling operation). During cooling operation, the refrigerant circulates through the compressor 111, the four-way valve 113, the outdoor heat exchanger 112, the expansion valve 114, the indoor heat exchanger 101, the four-way valve 113, and the compressor 111 in that order. That is, during cooling operation, the outdoor heat exchanger 112 functions as a condenser, and the indoor heat exchanger 101 functions as an evaporator. On the other hand, during heating operation, the refrigerant circulates through the compressor 111, the four-way valve 113, the indoor heat exchanger 101, the expansion valve 114, the outdoor heat exchanger 112, the four-way valve 113, and the compressor 111 in that order. That is, during heating operation, the indoor heat exchanger 101 functions as a condenser, and the outdoor heat exchanger 112 functions as an evaporator.

FIG. 2 is a flowchart showing a startup sequence (compressor startup sequence) of the compressor 111 when the air conditioner 10 according to Embodiment 1 starts operating. The following compressor startup sequence is performed by a control unit (not shown) provided in the air conditioner 10 controlling the drive current (motor drive current) of the drive motor (not shown) of the compressor 111 .

When the air conditioner 10 starts operating, the first temperature sensor 121 detects the outside air temperature, and the second temperature sensor 122 detects the compressor temperature. The detected outside air temperature and compressor temperature are compared with a first temperature threshold T1 (eg, 50° C.) and a second temperature threshold T2 (eg, 80° C.), respectively (S1, S2).

The control unit (determining unit) determines whether the compressor 111 is in an overload state at the start of operation based on the detected outside air temperature and compressor temperature. When at least one of the outside air temperature and the compressor temperature is below the threshold, that is, when "outside air temperature ≤ T1" or "compressor temperature ≤ T2" (S1 or S2 is NO), it is determined that the overload state is not present. Move to S3. If both the outside air temperature and the compressor temperature are higher than the threshold, that is, if "outside air temperature>T1" and "compressor temperature>T2" (both S1 and S2 are YES), it is determined that there is an overload condition, and the process proceeds to S4. Transition.

In S3, activation of the compressor 111 is started in the first activation sequence. The first startup sequence is a normal startup sequence that is applied when the compressor 111 is not overloaded, and is a startup sequence that is highly effective in suppressing vibration and noise during startup. FIG. 3 is a timing chart showing changes in motor drive current and compressor rotation speed in the first startup sequence.

When the compressor 111 is started, the motor drive current is usually forcibly increased midway to increase the compressor rotation speed to a desired rotation speed. Here, a compressor start-up sequence for finally increasing the compressor rotation speed to N3 (for example, 3500 rpm) is illustrated. Further, in Embodiment 1, it is assumed that the timing for increasing the motor drive current is controlled based on the compressor rotation speed. Therefore, the control unit according to the first embodiment monitors the compressor rotation speed.

In the first startup sequence, as shown in FIG. 3, the motor drive current is set to I1 at the start of startup, and the motor drive current is set to I2 when the compressor rotation speed reaches N11 (for example, 1500 rpm) (time t11). forced to rise. Furthermore, when the compressor rotation speed reaches N12 (for example, 2000 rpm) (time t12), the increase of the motor drive current is terminated. Then, when the compressor rotation speed reaches N3 (time t13) and the motor drive current stabilizes at I3, the start-up of the compressor 111 is completed (the compressor start-up sequence ends). Here, the motor drive current I3 is the motor drive current corresponding to the compressor rotation speed N3.

From the start to time t11, the amount of work increases as the compressor rotation speed increases, so the current also increases. Between time t11 and time t12, motor drive current I2 having a larger current value than motor drive current I3 is forcibly applied, and the current value becomes substantially constant. When the rising period of the motor drive current ends at time t12, the motor drive current changes (decreases) to a current corresponding to the compressor rotation speed at that time. From time t12 to time t13, the current increases as the work load increases as the compressor rotation speed increases until the compressor rotation speed stabilizes at N3.

In the first startup sequence, the timing for increasing the motor drive current (that is, the compressor rotation speeds N11 and N12) is set so as to suppress vibration and noise during startup.

In S4, activation of the compressor 111 is started in the second activation sequence. The second start-up sequence is applied when it is determined that the compressor 111 is in an overloaded state, and start-up failure is likely to occur in the normal start-up sequence. That is, the second startup sequence causes greater vibration and noise at the time of startup than the first startup sequence, but the compressor 111 can be reliably started even in an overloaded state. FIG. 4 is a timing chart showing changes in motor drive current and compressor rotation speed in the second startup sequence.

In the second startup sequence, as shown in FIG. 4, the motor drive current is set to I1 at the start of startup, and the motor drive current is set to I2 when the compressor rotation speed reaches N21 (for example, 2000 rpm) (time t21). forced to rise. Furthermore, when the compressor rotation speed reaches N22 (for example, 2500 rpm) (time t22), the increase of the motor drive current is terminated. When the compressor rotation speed reaches N3 (time t23) and the motor drive current stabilizes at I3, the start-up of the compressor 111 is completed (the compressor start-up sequence ends). In the second start-up sequence, the compressor rotation speed, which is the switching timing of the rising period of the motor drive current, is set to a higher rotation speed than in the first start-up sequence. That is, N21>N11 and N22>N12.

When the compressor 111 is started, the rotor of the drive motor is accelerated at the timing of increasing the motor drive current. In the second start-up sequence, the motor drive current is increased while the compressor rotation speed is higher than in the first start-up sequence. It becomes a thing. By delaying the timing of increasing the motor drive current in this manner, the rotor of the drive motor is accelerated in a state in which sufficient rotational inertia acts on the rotor of the drive motor. can be prevented (reliable start-up can be performed).

[Embodiment 2]
In the first embodiment described above, the timing for increasing the motor drive current is controlled based on the compressor rotation speed in the first startup sequence and the second startup sequence. However, the present invention is not limited to this, and it is also possible to control the timing of increasing the motor drive current based on the elapsed time from the start of activation.

For example, in the timing chart shown in FIG. 3, time t11 at which the compressor rotation speed is expected to reach N11 and time t12 at which the compressor rotation speed is expected to reach N12 are set in advance, and the control unit The motor drive current may be increased after the times t11 and t12 have passed.

Similarly, in the timing chart shown in FIG. 4, a time t21 at which the compressor rotation speed is expected to reach N21 and a time t22 at which the compressor rotation speed is expected to reach N22 are set in advance, and the control unit may increase the motor drive current when times t21 and t22 have passed.

In the compressor startup sequence according to the second embodiment, instead of monitoring the compressor rotation speed, the controller can execute the compressor startup sequence by measuring time with a timer.

[Embodiment 3]
In the first embodiment described above, the current values (ie, I1, I2) of the motor drive current (starting current) to be increased stepwise during starting are the same for both the first starting sequence and the second starting sequence. However, the present invention is not limited to this, and the starting current may be different between the first starting sequence and the second starting sequence (the motor drive current I3 to be finally reached is the same. ).

Specifically, the starting currents I1' and I2' in the second starting sequence may be larger than the starting currents I1 and I2 in the first starting sequence (I1'>I1 and I2'>I2). Thus, by making the starting current in the second starting sequence larger than the starting current in the first starting sequence, it is possible to more reliably prevent the compressor 111 from failing to start.

[Embodiment 4]
In Embodiment 1 above, the overload state for executing the second startup sequence is determined based on the outside air temperature and the compressor temperature. However, the present invention is not limited to this, and it is also possible to determine the overload condition for performing the second activation sequence based on other parameters.

For example, it is conceivable to determine the overload condition for executing the second startup sequence based on the outside temperature and the elapsed time since the previous shutdown. In other words, if enough time has passed since the last shutdown, the compressor temperature is expected to drop to the extent that it does not become overloaded. is expected to be up to

Therefore, in the compressor startup sequence according to the fourth embodiment, the outside air temperature is higher than the first temperature threshold T1 (for example, 50° C.), and the time threshold ( for example, one hour), the compressor 111 may be considered overloaded and a second start-up sequence may be implemented.

The embodiments disclosed this time are exemplifications in all respects and are not grounds for restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the claims. In addition, all changes within the meaning and range of equivalents to the scope of claims are included.

10 air conditioner 100 indoor unit (indoor unit)
101 indoor heat exchanger 102 indoor fan 110 outdoor unit (outdoor unit)
111 compressor 112 outdoor heat exchanger 113 four-way valve 114 expansion valve 115 outdoor fan 121 first temperature sensor 122 second temperature sensor

Claims (3)

A determination unit that determines whether the compressor is in an overloaded state at the start of operation;
A control unit that performs start-up control of the compressor,
The control unit
when the determining unit determines that the compressor is not in an overloaded state , starting the compressor in a first starting sequence;
when the determining unit determines that the compressor is in an overloaded state , starting the compressor in a second starting sequence ;
The first and second startup sequences are startup sequences for increasing the compressor rotation speed to a desired rotation speed, including a period during which the motor drive current of the compressor is forcibly increased during startup,
The air conditioner according to claim 1, wherein, in the second start-up sequence, timing for increasing the motor drive current is shifted later than in the first start-up sequence. The air conditioner according to claim 1 ,
The first and second startup sequences are startup sequences for increasing the motor drive current at the timing when the compressor rotation speed reaches a predetermined compressor rotation speed,
The air conditioner according to claim 1, wherein in the second activation sequence, the predetermined compressor rotation speed is set to a greater compressor rotation speed than in the first activation sequence. The air conditioner according to claim 1 or 2 ,
The determination unit determines that the compressor is in an overload state when the outside air temperature is higher than a first temperature threshold and the compressor temperature is higher than a second temperature threshold. machine.

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