JPH04126942A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent an operation of a compressor from being frequently stopped by a method wherein a second pressure switch detects a variation in a discharging pressure, an electrical energization for an auxiliary heater is stopped, and an increasing of the discharging pressure is restricted. CONSTITUTION:An outdoor blower control device 12 normally sets an outdoor blower 11 to have a maximum amount of air when a heating operation is carried out. Hot air is supplied by an auxiliary heater 8 to an indoor heat exchanger 3 and then a condensing temperature of refrigerant is increased. The condensing temperature and a discharging pressure of a compressor 1 are rapidly increased when the indoor and outdoor temperatures are high. At this time, a second pressure switch 7 reaches the second predetermined value and then the control device 12 sets an amount of air of the blower 11 low or stops the operation of the blower 11. Evaporating capability of an outdoor heat exchanger 5 is reduced and the discharging pressure is decreased. A heater control device 10 stops an electrical energization for the auxiliary heater 8 and decreases the discharging pressure. As the discharging pressure is decreased to the third predetermined value, a time counting of a timer 9 is started and the control device 10 returns the setting of the air volume of the blower 11 to its maximum value. The heater control device 10 stops an electrical energization for the auxiliary heater 8 until the time counting of the timer 9 is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an air conditioner having an auxiliary heater on the indoor side.

BACKGROUND OF THE INVENTION In recent years, there has been a demand for air conditioners to be more and more compact for both the outdoor unit and the indoor unit.

Therefore, in some indoor units, the auxiliary heater for heating is built into the indoor heat exchanger, and some are placed upwind of the indoor heat exchanger.

On the other hand, in general, air conditioners are equipped with a pressure switch that responds to the discharge pressure in order to protect the compressor from abnormal increases in discharge pressure. I'm trying to stop it.

However, during heating operation, the auxiliary heater built into the indoor heat exchanger that acts as a condenser, or the auxiliary heater placed upwind of the indoor heat exchanger, directly or indirectly connects the indoor heat exchanger. In order to increase the condensing pressure by heating, which in turn increases the discharge pressure of the compressor, there is a problem in that the pressure switch is activated frequently and the operation is stopped each time.

Therefore, as shown in Japanese Utility Model Application Publication No. 1-63947, for example, a temperature sensor such as a thermistor is attached to the indoor heat exchanger that serves as the condenser, and the condensation temperature is detected and the pressure switch is activated. Some are designed to stop the power supply to the auxiliary heater, suppress abnormal increases in condensing pressure, that is, discharge pressure, and prevent frequent activation of the pressure switch, or reduce the air volume of the outdoor fan at the same time as the pressure switch is activated. A system has been devised that reduces the evaporation pressure, that is, the compressor suction pressure, thereby increasing the effect of preventing an abnormal rise in the discharge pressure.

Problems to be Solved by the Invention However, the above-mentioned conventional air conditioner has problems during heating operation.
Under high load conditions, where the outside air temperature is high and the indoor temperature is also high, the discharge pressure rises rapidly, and a temperature sensor such as a thermistor attached to the indoor heat exchanger has the disadvantage of not being able to accurately detect the condensing temperature. That is, FIG. 3 is a diagram showing changes in discharge pressure, changes in condensing temperature, and changes in temperature detected by the temperature sensor when heating operation is performed in a high load state. It can be seen that even if the actual condensation temperature exceeds the predetermined value ↑1 determined to stop the supply of electricity to the auxiliary heater, the temperature detected by the temperature sensor has not yet reached the predetermined value T1. This is due to the heat capacity of the indoor heat exchanger and the temperature sensor, and a delay in detection by the temperature sensor due to a rapid change in condensing temperature is an unavoidable phenomenon. For this reason,
There is a drawback that the control to stop the energization to the auxiliary heater is delayed, and the discharge pressure continues to rise abnormally by that amount, and eventually the pressure switch is activated and the operation of the compressor is stopped.

In addition, in separate tights air conditioners used for building air conditioning, the distance between the installed outdoor unit and indoor unit varies from several meters to several tens of meters, and generally the compressor is attached to the outdoor unit. Because the pressure switch detects this and stops compressor operation, the relationship between the discharge pressure and the condensing temperature of the indoor/outdoor exchanger is not uniform, especially for the refrigerant connecting between the indoor and outdoor units. When the length of piping is long or the difference in height between indoor and outdoor units is large, the condensing pressure, or condensing temperature, of the indoor heat exchanger becomes significantly lower than the discharge pressure, so the condensing temperature is lower than the standard length of piping. This also has the disadvantage that the discharge pressure reaches the operating point of the pressure switch before reaching the predetermined value T1, and the operation of the compressor stops. Figure 4 shows the change in discharge pressure brim condensation temperature when the length of the refrigerant piping connecting the indoor and outdoor units is long (long piping) and when there is a large height difference between the indoor and outdoor units (lk'7) (height insertion). So, T2 shown by the - dotted chain line is the standard piping length 6,
．． 7 In the case of an indoor unit installed at It can be seen that at T3 of ignition, the discharge pressure reaches the operating point of the pressure switch before the condensing temperature reaches the predetermined value T1, and the operation of the compressor is stopped.

In addition, in conventional air conditioners that simultaneously turn on the auxiliary heater to stop 9, reduce the air volume of the outdoor fan, and return to normal, when trying to suppress the discharge pressure, the two effects overlap, causing the discharge pressure to drop rapidly, and vice versa. When the control is released, the discharge pressure increases rapidly, and depending on the operating conditions, the discharge pressure repeatedly decreases and increases rapidly. Not only is stable operation impossible, but such operation places an excessive burden on the compressor. This has the disadvantage of impairing the reliability of the air conditioner.

The present invention solves the above-mentioned conventional problems, and aims to provide an air conditioner that prevents frequent operation of the pressure switch and performs stable operation.

Means for Solving the Problem In order to achieve this object, the air conditioner of the present invention includes a compressor, an outdoor heat exchanger, an outdoor blower provided near the outdoor heat exchanger, and the above-mentioned air conditioner. an indoor heat exchanger connected to the compressor and the outdoor heat exchanger to function as a radiator via a refrigerant flow path; and an auxiliary heater disposed on the upwind side of the indoor heat exchanger; a first pressure switch that detects refrigerant pressure immediately after discharge from the compressor and operates to stop operation of the compressor when the detected pressure exceeds a first predetermined value; The refrigerant pressure immediately after discharge from the compressor is detected, and the detected pressure is lower than the first predetermined value.
A detection signal is output when the predetermined value of ``2'' is reached, and then,
a second pressure switch that releases the detection signal when the pressure falls below a third predetermined value that is lower than the second predetermined value; , an outdoor side blower control device that restores the air volume of the outdoor side blower by canceling the detection signal of the second pressure switch; and a time measurement is started by canceling the detection signal of the second pressure switch, and after a predetermined period of time has elapsed. , a heater control device that stops energizing the auxiliary heater in response to a detection signal from the second pressure switch, and continues to stop energizing the auxiliary heater while the timer is counting time. It is something that will be done.

Function Since the air conditioner of the present invention has the above configuration, the second
The pressure switch reliably detects the change in the discharge pressure, and before the discharge pressure reaches the operating point of the first pressure switch, the power supply to the auxiliary heater is stopped to suppress the increase in the discharge pressure.
Since the timer continues to stop energizing the auxiliary heater for a certain period of time, stable operation can be performed without interfering with the control of the discharge pressure by controlling the air volume of the outdoor side blower.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 shows a block diagram of a heat pump type refrigeration cycle of an air conditioner according to an embodiment of the present invention.

In FIG. 1, compressor 1. Four-way valve 2. Indoor heat exchanger 3. Pressure reducing device4. The outdoor heat exchanger 5 and the like are successively connected to form a heat pump type refrigeration cycle. Thus, during the heating operation, the refrigerant flows in the direction of the solid arrow A, and during the cooling operation, the four-way valve 2 is switched, so that the refrigerant flows in the direction of the broken arrow B.

The refrigerant pipe immediately after the refrigerant discharge port of the compressor 1 is equipped with a first pressure switch 6 that detects the discharge pressure and operates to stop the operation of the compressor 1 when the detected pressure exceeds a predetermined value. detecting the discharge pressure and outputting a detection signal when the detected pressure exceeds a second predetermined value that is lower than the first predetermined value;
Thereafter, a second pressure switch 7 releases the detection signal when the pressure becomes equal to or less than a third predetermined value, which is lower than the second predetermined value.
will be provided. An auxiliary heater 8 is arranged near the indoor heat exchanger 3 and on the upwind side of the heat exchange air. Arrow C in the figure indicates the direction of air flowing through the indoor heat exchanger 3. Furthermore, a timer 9 starts timing by canceling the detection signal of the second pressure switch 7, and after a predetermined period of time has passed, a timer 9 stops timing, and the power supply to the auxiliary heater 8 is stopped by the detection signal. , a heater control device 1o is provided which continues to stop supplying electricity to the auxiliary heater 8 while the timer 9 is measuring time. An outdoor fan 11 is provided near the outdoor heat exchanger 5, and its operation and operation are controlled by an outdoor fan control device 12.
It stops and controls the air volume.

Now, in the air conditioner configured in this way, the high temperature and high pressure Ganu refrigerant discharged from the compressor 1 during heating operation is as follows:
The air passes through the four-way valve 2 to the indoor heat exchanger 3, is cooled and condensed by the air sucked in from the indoor side by an indoor blower (not shown), and conversely warms the air to heat the room. During heating operation, the outdoor blower control device 12 normally sets the outdoor blower 11 to the maximum air volume state.

Further, the auxiliary heater 8 is installed to compensate for the lack of heating capacity in times of severe cold or at the beginning of heating operation, but its energization is controlled by a control device (not shown) according to the indoor temperature setting and the indoor temperature. . When the auxiliary heater 8 is energized, the air supplied to the indoor heat exchanger 11 ・＼ finisher 3 is heated by the auxiliary heater 8, so air that is several degrees higher than the indoor temperature is transferred to the indoor heat exchanger 3. The refrigerant condensing temperature inside the indoor heat exchanger 3 increases. Therefore, in intermediate seasons such as spring and autumn when the indoor and outdoor temperatures are relatively high, the condensing temperature and, by extension, the discharge pressure of the compressor 1 rise rapidly with the start of heating operation.

At this time, due to the operation of the first pressure switch, the second pressure switch 7 reaches the second predetermined value first, and based on the detection signal, the outdoor fan control device 12 sets the air volume of the outdoor fan 11 to a small air volume. Alternatively, the outdoor fan 11 is stopped. By reducing the air volume of the outdoor fan 11 or stopping it, the outdoor heat exchanger 5 acts as an evaporator during heating operation, so the evaporation capacity of the heat pump cycle is reduced and the discharge pressure is reduced. .

At the same time, the heater control device 10 stops energizing the auxiliary heater 8 based on the detection signal from the second pressure switch 7 . By stopping the energization to the auxiliary heater 8, the effect of lowering the discharge pressure becomes greater.

When the discharge pressure decreases to a third predetermined value, the detection signal of the second pressure switch 7 is canceled and the timer 9 starts timing. By this release, the outdoor fan control device 12 returns the air volume setting of the outdoor fan 11 to the maximum state, but the heater control device 1o continues to stop energizing the auxiliary heater 8 until the timer 9 finishes timing. do.

Here, the operations of the timer 9 and heater control device 10 of this embodiment will be explained based on the flowchart of FIG.

That is, in step 1, the second pressure switch 7
The presence or absence of a detection signal is determined. When the discharge pressure rises and the detection signal becomes 'active', the process proceeds to step 2, where the heater prohibition flag is turned on, and the process proceeds to step 3. In step 3, the auxiliary heater 8 is prohibited from being energized, and the process returns to step 1 again. In this manner, when the discharge pressure increases and is detected by the second pressure switch 7, the operation flow is as described above 9, and energization of the auxiliary heater 8 is prohibited.

In step 1, the discharge pressure decreases and the detection signal becomes 13 \
7' When the result is "no", the process proceeds to step 4, where it is determined whether or not the auxiliary heater 8 is prohibited from being energized in the state detected by the second pressure switch 7, using the heater prohibition flag. Originally, when the discharge pressure is low and the second pressure switch 7 is not detecting it, that is, the heater prohibition flag is "OF".
If F'", return to step 1 and repeat steps 1 to 4.

If the auxiliary heater 8 is prohibited from being energized while the second pressure switch 7 is detecting it, that is, if the heater prohibition flag 1]2 is “ON”, proceed to step 6, and the timer 9 starts timing. Start. In step 6, timer 9
It is determined whether the timer 9 is in the process of timing or has finished timing. If the timer 9 is in the process of timing, the process proceeds to step 3, where the auxiliary heater 8 continues to be prohibited from being energized, and returns to step 1 again.The discharge pressure decreases and When the detection signal of the pressure switch 7 of 2 is released,
The operation flow as above 9, second pressure switch 7
When the detection signal is released, the timer 9 starts counting time, and the auxiliary heater 8 is prohibited from being energized while the timer 9 is counting time.

14.＼ / When the timer 9 finishes counting, proceed to step 7, clear the timer 9, proceed to step 8, set the heater prohibition flag to 0FFI, proceed to step 9, turn off the auxiliary heater 8.
Allow power to be energized and return to step 1 again. When the timer 9 finishes counting, the auxiliary heater 8 is allowed to be energized according to the operation flow described above.

In this way, the heater control device 10 shown in FIG. In this case, the supply of electricity to the auxiliary heater 8 can be continued and stopped for a predetermined period of time after the detection signal is released.

Therefore, before the operating point of the first pressure switch 6 is reached, the energization to the auxiliary heater 8 is stopped to suppress the increase in discharge pressure, and the effect of controlling the discharge pressure by controlling the air volume of the outdoor side blower 11 is improved. Due to the effect of the discharge pressure control by controlling the heater 8, after the discharge pressure has decreased, even if the detection signal is canceled, the power supply to the auxiliary heater 8 is continued for a predetermined period of time. Since there is no increase or decrease in the discharge pressure due to energization or shutdown of the heater 8, the outdoor ventilation (11
The rise and fall of the discharge pressure by controlling the air volume is relatively gentle.

Of course, even if the power supply to the auxiliary heater 8 is stopped, the first pressure switch 6 is activated if the discharge pressure abnormally increases due to other factors such as clogging of the indoor unit's suction filter. Therefore, it is natural to stop the operation of the compressor 1 and protect the air conditioner.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the air conditioner of the present invention detects the refrigerant pressure immediately after discharge from the auxiliary heater arranged on the windward side of the indoor heat exchanger and the compressor, and when the detected pressure is around the first predetermined value. a first pressure switch that operates to stop the operation of the compressor when the pressure exceeds the first pressure switch; and a second pressure switch that detects the refrigerant pressure immediately after discharge from the compressor during heating operation; A detection signal is output when the value becomes -1- or higher than a predetermined value, and then a second
a second pressure switch that releases the detection signal when the pressure becomes equal to or less than a third predetermined value that is lower than a predetermined value; and a heater control device that stops energizing the auxiliary heater based on the detection signal of the second pressure switch. During heating operation, even if the auxiliary heater placed on the windward side of the indoor heat exchanger is energized, the second pressure switch can reliably follow sudden changes in discharge pressure. At the same time, it is possible to issue a detection signal for the second pressure switch before the first pressure switch is activated, to stop the supply of electricity to the auxiliary heater, and to prevent the compressor from frequently stopping operation. , regardless of the piping distance between the outdoor unit and the indoor unit.
The above control can be reliably executed.

Moreover, a timer is provided that starts timing when the detection signal of the second pressure switch is released and ends timing after a predetermined period of time, and the heater control device prevents power supply to the auxiliary heater from being stopped while the timer is timing. To ensure continuity, even when combined with discharge pressure control, which is performed by changing the air volume of the outdoor fan installed near the outdoor heat exchanger during heating operation,
Outdoor method 17 ・＼ The disadvantage of the conventional technology is that the effect of controlling the discharge pressure by controlling the fan air volume and the effect of controlling the discharge pressure by controlling the auxiliary heater influence each other, resulting in the discharge pressure repeatedly rising and falling repeatedly. This allows stable operation of the air conditioner.

Furthermore, the heater control device reliably stops energizing the auxiliary heater while receiving the detection signal, so that an increase in discharge pressure can be reliably suppressed, resulting in stable operation of the air conditioner. becomes possible.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an air conditioner according to an embodiment of the present invention, Fig. 2 is a flowchart showing the operation details of the timer and heater control device shown in Fig. 1, and Fig. 3 is a block diagram of a conventional air conditioner. Characteristic diagram of discharge pressure, condensing temperature, and temperature detected by the temperature sensor when heating operation is performed under high load, Part 4
The figure is a characteristic diagram of discharge pressure and condensing temperature when the refrigerant piping connecting the indoor and outdoor units of a conventional air conditioner is long or has a height insertion. 18 /\-/ 1...Compressor, 3...Indoor heat exchanger, 5...Outdoor heat exchanger, 6...First Pressure switch, 7...Second pressure switch, 8
...Auxiliary heater, 9...Timer, 1
o...Heater control device, 11...Outdoor side blower, 12...Outdoor side blower control device. Name of agent: Patent attorney Akira Okaji and two others

Claims (1)

[Claims] a compressor, an outdoor heat exchanger, an outdoor blower provided near the outdoor heat exchanger, and a refrigerant flow path connected to the compressor and the outdoor heat exchanger to act as a condenser. The refrigerant pressure immediately after discharge from the connected indoor heat exchanger, the auxiliary heater arranged on the upwind side of the indoor heat exchanger, and the compressor is detected, and when the detected pressure becomes a first predetermined value or more, a first pressure switch that operates to stop the operation of the compressor; and a second predetermined pressure switch that detects refrigerant pressure immediately after discharge from the compressor during heating operation, and the detected pressure is lower than the first predetermined value. a second pressure switch that issues a detection signal when the pressure exceeds a predetermined value, and then releases the detection signal when the pressure falls below a third predetermined value that is lower than the second predetermined value; an outdoor side blower control device that reduces the air volume of the outdoor side blower in response to a detection signal of the second pressure switch, and restores the air volume of the outdoor side blower by canceling the detection signal of the second pressure switch; and a detection signal of the second pressure switch. A timer that starts timing when the signal is released and ends timing after a predetermined time has elapsed; and a timer that stops energizing the auxiliary heater in response to a detection signal from the second pressure switch, and supplies electricity to the auxiliary heater while the timer is timing. An air conditioner characterized by having a heater control device that continues to stop energizing the air conditioner.