JPH0127349B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigerator, and more particularly to an improvement in measures for preventing an abnormal rise in high pressure in a refrigerant circulation system.

(Prior Art) Conventionally, this type of refrigerator has been provided with a refrigerant pressure detection means for detecting the refrigerant pressure in the refrigerant circulation system, as disclosed in, for example, Japanese Utility Model Application No. 50-65233, The rotation speed of the condenser fan can be switched between low speed and high speed, and when the high pressure in the refrigerant circulation system exceeds a set value for compressor protection, the rotation speed of the condenser fan can be changed from low speed to high speed. There is a known system that increases the cooling capacity of the condenser by switching the compressor to suppress the rise in high pressure above the set value, and allows the compressor to operate continuously without activating the high pressure switch. ing.

(Problem to be Solved by the Invention) Therefore, by further developing the above technology, the rotation speed of the condenser blower fan can be increased or decreased in multiple stages or steplessly depending on the magnitude relationship between the high pressure and the set value. It is conceivable that the high pressure can be converged and maintained at approximately the set value by variably controlling the cooling capacity of the condenser. In this case, since it is necessary to accurately maintain the high pressure with a small hunting width, it is necessary to set a relatively large time constant for changing the speed of the blower fan and gradually change the speed.

However, in that case, when the condenser is installed outdoors, the high pressure can be well controlled to converge to the set value during steady operation of the refrigerator due to the large time constant of the speed change of the blower fan. When disturbances such as strong winds occur, the following drawbacks occur: In other words, when a disturbance such as strong wind occurs in a situation where the outside temperature is low, the cooling capacity of the condenser increases significantly, the rotation of the ventilation fan stops, and the high pressure suddenly decreases. Then, when the strong wind stops, the cooling capacity of the condenser suddenly decreases and the high pressure starts to rise suddenly, but at this time, even if the blower fan starts rotating once the high pressure has risen to the set value. , due to the large time constant, the rotational speed increases gradually, and the cooling capacity of the condenser also increases gradually, so the high pressure continues to rise, and as a result,
This has the disadvantage that the high pressure switch will eventually operate, causing the compressor to shut down.

The present invention has been made in view of the above, and its purpose is to successfully converge the high pressure to a set value even if the high pressure suddenly increases after disturbances such as strong winds have passed. The purpose is to prevent the compressor from operating and ensure continuous operation of the compressor.

(Means for Solving the Problems) In order to achieve the above object, the present invention quickly increases the cooling capacity of the condenser when the high pressure rises rapidly after the disturbance has passed, so that the high pressure converges to the set value. let

That is, the specific configuration of the present invention, as shown in FIG. 1, includes a refrigerant pressure detection means 10 for detecting the refrigerant pressure of a refrigerant circulation system 6 having a condenser 2 arranged outdoors, and the refrigerant pressure detection means. 10, the rotational speed of the blower fan 2a of the condenser 2 is increased to a predetermined value so that the high pressure P becomes the set value (pset) according to the magnitude relationship with the set value (Pset) of the high pressure P. The object of the present invention is a refrigerator equipped with a control means 20 that performs increase/decrease control with a time constant. And the condenser 2
fan stop detection means 15 for detecting that the blower fan 2a has stopped; and the refrigerant pressure detection means 1.
0 and the output of the fan stop detection means 15,
After the blower fan 2a of the condenser 2 is stopped, the high pressure P
A correction means 21 is provided for correcting the control means 20 so that when Pset exceeds a set value (Pset), the blower fan 2a of the condenser 2 is restarted at a predetermined low to medium rotational speed (R ₀ ).

(Function) With the above configuration, in the present invention, during steady operation without disturbance, the rotational speed of the blower fan is gradually changed with a predetermined large time constant, so the high pressure is set accurately with a small hunting width. converges to the value.

Therefore, if a disturbance such as strong wind occurs outdoors in the above-mentioned steady operating state, the cooling capacity of the condenser 2 will increase significantly, the high pressure will suddenly drop, and the rotation of the blower fan 2a may stop. be. In this case, when the disturbance disappears and the high pressure rises to the set value, the condenser blower fan immediately rotates at a predetermined low to medium speed, which quickly increases the cooling capacity of the condenser and increases the high pressure. Since it follows the rise in pressure well, the rise in high-pressure pressure is effectively suppressed, the operation of the high-pressure switch is prevented, and continuous operation of the compressor is enabled.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows an embodiment applied to an air conditioner, where A is an outdoor unit placed outdoors, B is an indoor unit, and
The outdoor unit A includes a compressor 1 and an outdoor heat exchanger 2 having a blower fan 2a, and the indoor unit B includes an expansion mechanism 3 and an indoor heat exchanger 4 having a blower fan 4a. ing. The above-mentioned devices 1 to 4 are connected by refrigerant pipes 5 to form a refrigerant circulation system 6, and the compressor 1
By circulating the refrigerant in the direction shown by the arrow in the figure, the heat contained in the refrigerant is radiated to the outside air in the outdoor heat exchanger 2, which acts as a condenser, and then transferred from the indoor air in the indoor heat exchanger 4, which acts as an evaporator. The interior of the air-conditioned room is cooled by repeatedly absorbing heat. Note that 7 is an accumulator provided in the outdoor unit A.

A refrigerant pressure sensor 10 is provided in the refrigerant pipe 5 downstream of the outdoor heat exchanger 2 in the refrigerant circulation system 6 as a refrigerant pressure detection means for detecting the refrigerant pressure (high pressure) in the refrigerant pipe 5. The refrigerant pressure sensor 10 is connected to a controller 11 that drives and controls the compressor 1 and the blower fans 2a, 4a of the outdoor unit A and the indoor unit B so as to be able to send and receive signals.

As shown in FIG. 3, the controller 11 includes a run/stop switch 12 disposed inside the air-conditioned room for switching between running and stopping, and a switch 12 and the refrigerant pressure sensor 10 disposed inside the air-conditioned room. It is equipped with a microcomputer (microcomputer) 13 that receives the output of the outdoor fan 2a of the outdoor heat exchanger 2, and a variable speed device 14 for changing the speed of the outdoor blower fan 2a of the outdoor heat exchanger 2. Furthermore, inside the controller 11, a blower fan 2a of the outdoor heat exchanger (condenser) 2 is installed depending on the presence or absence of output current from the variable speed device 14.
Fan stop detection means 1 for detecting that the fan has stopped
The output of the fan stop detection means 15 is input to the microcomputer 13.

Next, the operation of the upper microcomputer 13 will be explained based on the flowchart of FIG. First, the operation is started based on the operation side switching of the operation/stop switch 12,
In step _S1 , the compressor 1 and the indoor blower fan 4a are driven, and in step _S2 , the outdoor blower fan 2a of the outdoor heat exchanger 2 is initially driven so that the starting current of the variable speed device 14 does not exceed the maximum allowable value. Gradually increase the rpm and perform a soft start. Then, in step _S3 , the outdoor fan 2a waits until the rotational speed reaches the maximum rotational speed, and in step _S4 , the high-speed rotation at this maximum rotational speed is forcibly continued for a predetermined period of time.

Subsequently, in step _S5 , the refrigerant pressure sensor 1
After reading the high pressure signal from 0, it is determined in step _S6 whether or not the high pressure P is equal to the set value (Pset) for compressor 1 protection in order to perform convergence control of the high pressure to the set value. , if P≠Pset is NO, then in step _S7 it is determined whether the high pressure P exceeds the set value (Pset), and P>Pset.
In the case of YES, in step _S8 , the variable speed device 14 is controlled to increase the rotation speed of the outdoor blower fan 2a with a predetermined large time constant, thereby increasing the cooling capacity of the outdoor heat exchanger 2 and increasing the high pressure. pressure P
decrease toward the set value (Pset). on the other hand,
If P<Pset is NO, it is determined in step _S9 whether or not there is an outdoor fan stop signal from the fan stop detection means 15, and the outdoor fan stop signal is not received.
If NO, step _S10 turns on the outdoor fan 2.
By controlling the variable speed device 14 to lower the rotation speed of a with a predetermined large time constant,
The cooling capacity of the outdoor heat exchanger 2 is reduced, the high pressure P is increased toward the set value (Pset), and the process returns to step _S5 . Also, in step _S6 above, P=Pset
If YES, step _S11 turns on outdoor fan 2.
By maintaining the rotation speed of a, the high pressure P is maintained at the set value (Pset), and the process proceeds to step _S5 .
Return to

When the outdoor fan stop signal is received in step _S9 ( _YES ), the high pressure signal from the refrigerant pressure detection means 10 is read in step _S12 , and the high pressure P is set to the set value ( Pset) is exceeded, and P≦Pset.
When NO, it is determined that it is not time to restart the outdoor ventilation fan 2a, and the process returns to step _S12 , while P>
When Pset is YES, it is determined that it is time to restart, and in step _S14 , the variable speed device 14 is controlled to immediately restart the outdoor fan 2a at a predetermined low to medium rotation speed _R0 , and step _S5 Return to

Therefore, through the series of processing operations from step _S5 to step _S11 described above, outdoor heat exchange is performed so that the high pressure P becomes the set value (Pset) according to the magnitude relationship between the high pressure P and the set value (Pset). A control means 20 is configured to increase or decrease the rotational speed of the blower fan 2a of the air blower 2 at a predetermined large time constant. Furthermore, if it is determined that the outdoor fan stop signal has been received in step _S9 , that is, after the blower fan 2a of the outdoor heat exchanger 2 has been stopped, steps _S12 to _S14 are performed.
When the high pressure P exceeds the set value ( _Pset ) after performing each processing operation in constitutes a correction means 21 that corrects the control to increase the rotational speed of the outdoor blower fan 2a, which is gradually performed in step _S8 .

Furthermore, in this embodiment, the run/stop switch 1
2 constitutes a startup detection means that detects startup, and the operation of the microcomputer 13 causes the outdoor blower fan 2a of the outdoor heat exchanger 2, which acts as a condenser, to be activated for a predetermined time at startup. The first one was made to rotate at high speed for a period of t.
a second control means configured to control the rotation speed of the outdoor blower fan 2a of the outdoor heat exchanger 2 so as to maintain the high pressure P at a set value (Pset) after the high-speed rotation for the predetermined time t; It consists of

Therefore, in the above embodiment, during steady operation without disturbance, the rotation speed of the blower fan 2a of the outdoor heat exchanger 2 is gradually changed with a predetermined large time constant, so that the high pressure P is small. Accurately converges to the set value (Pset) within the hunting width.

On the other hand, as shown in FIG. 5, when the cooling capacity of the outdoor heat exchanger 2 increases and the high pressure P starts to decrease at point A where a disturbance such as a strong wind occurs, the blower fan 2a of the outdoor heat exchanger 2 The rotation speed begins to gradually decrease in order to reduce the cooling capacity, and if the high pressure P still does not converge to the set point (Pset), the rotation eventually stops. After point B, when the disturbance has passed, the cooling capacity of the outdoor heat exchanger 2 suddenly decreases, and the high pressure P rises rapidly, and when it exceeds the set value (Pset), the outdoor blower fan 2a restarts. do. In this case, normally, the rotation speed increases gradually due to a large time constant and the cooling capacity increases gradually, so the increase in high pressure P cannot be effectively suppressed and continues to increase, causing the high pressure switch to This may lead to activation. However, in the present invention, the rotation speed of the outdoor ventilation fan 2a is immediately reduced to a predetermined low to medium rotation speed.
The cooling capacity of _the outdoor heat exchanger 2 follows the increase in the high pressure P well. As a result, the increase in the high pressure P is effectively suppressed, and it converges toward the set value (Pset) with high accuracy. Therefore, it is possible to effectively suppress a sudden increase in the high pressure P after the disturbance has subsided, to prevent the high pressure switch from operating, and to perform continuous operation of the compressor 1.

Moreover, as shown in FIGS. 3 and 4,
At startup, the high pressure P of the refrigerant circulation system 6 tries to rise suddenly, but at the same time, the blower fan 2a of the outdoor heat exchanger 2 starts soft, and then continues to rotate at the maximum rotation speed for a predetermined time t. By continuing for a while, the rapid increase in the high pressure P is effectively suppressed, and the high pressure P is almost stabilized at a predetermined value P ₀ that is less than the set value (Pset) corresponding to the high speed rotation of the blower fan 2a. Therefore, the high pressure P changes while responding well to the next rotational speed control of the outdoor blower fan 2a, and as a result, the high pressure P
will smoothly move toward the set value (Pset), and will converge to the set value (Pset) with high accuracy even in a short convergence time. Therefore, high pressure P at startup
The high-pressure pressure switch does not operate due to a sudden increase in the pressure, and the compressor 1 can be operated continuously, and the indoor heat exchange is achieved by accurately converging control to the set value (Pset) of the high-pressure pressure P. Frost formation on the container 4 (evaporator) and increase in load on the compressor 1 can be effectively suppressed.

(Effects of the Invention) As explained above, according to the refrigerator of the present invention, the time constant of the speed change of the condenser blower fan during steady operation is set large, and the When the high pressure rises to the set value, the blower fan is restarted at a low to medium rotation speed, so during steady operation without disturbances, the high pressure can be accurately converged to the set value with a small hunting width, and Even when a disturbance such as strong wind occurs, the increase in the cooling capacity of the condenser can be made to closely follow the sudden rise in high pressure after the disturbance has passed, effectively suppressing the rise in high pressure. , the operation of the high-pressure switch can be prevented and the compressor can be operated continuously.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 5 show embodiments of the present invention, FIG. 2 is a refrigerant piping system diagram, FIG. 3 is a block diagram showing the internal configuration of the controller, and FIG. 4 is a diagram for explaining the operation of the microcomputer. The flowchart, FIG. 5, is a diagram for explaining how the high pressure converges to the set value. 2...Outdoor heat exchanger (condenser), 2a...Blower fan, 6...Refrigerant circulation system, 10...Refrigerant pressure sensor (refrigerant pressure detection means), 15...Fan stop detection means, 20...Control Means, 21...Correction means.

Claims (1)

[Claims] 1 Refrigerant pressure detection means 1 for detecting the refrigerant pressure of the refrigerant circulation system 6 having the condenser 2 located outdoors
0 and the output of the refrigerant pressure detection means 10, the blower fan 2a of the condenser 2 is operated so that the high pressure P becomes the set value (Pset) according to the magnitude relationship between the high pressure P and the set value CPset of the high pressure P. control means 20 for controlling the rotational speed of the condenser 2 to increase or decrease with a predetermined large time constant, fan stop detection means 15 for detecting that the blower fan 2a of the condenser 2 has stopped, the refrigerant pressure detection means 10 and Upon receiving the output of the fan stop detection means 15, the blower fan 2a of the condenser 2
a correction means 21 for correcting the control means 20 so that the blower fan 2a of the condenser 2 restarts at a predetermined low to medium rotational speed _R0 when the high pressure P exceeds a set value (Pset) after the high pressure P has stopped. A refrigerator characterized by the following features: