JPS62129661A - Air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a multi-type air conditioner consisting of an outdoor unit and a plurality of indoor units.

[Technical background of the invention]

Conventionally, in this type of air conditioner, the outdoor unit is equipped with a variable capacity compressor, and the operating frequency of this compressor is controlled according to the total air conditioning load of each indoor unit.
Some systems are designed to obtain optimal performance corresponding to the number of operating indoor units and the air conditioning load of each indoor unit, thereby improving comfort and energy saving effects.

By the way, in such an air conditioner, a high pressure protection device such as a high pressure switch is attached to the high pressure side refrigerant piping of the refrigeration cycle, and if the high pressure side pressure rises abnormally due to overload operation etc. and the high pressure switch is activated, the high pressure switch will be activated. Operations have been stopped to protect the compressor and other operating equipment.

However, at the start of heating operation, especially during the rising period when the operating frequency of compressor 1 reaches the target value from the lowest operating frequency, an overload condition often occurs, and the pressure on the high pressure side suddenly increases abnormally, causing the high pressure switch to switch off. may be activated, leading to unnecessary operation stoppages.

Therefore, conventionally, the input current to the compressor (current flowing to the drive motor) is detected, and when the input current exceeds a set value (overload operation), the operating frequency of the compressor is lowered. This prevents unnecessary activation of the high pressure switch. This operating frequency control is shown in FIG.

That is, at the start of heating operation, the operating frequency F of the compressor 1 increases from the predetermined lowest operating frequency toward the target value corresponding to the total air conditioning load of each indoor unit, but at that time, the When the input current (2) exceeds the set value (2), the operating frequency F of the compressor is decreased by one step (for example, 5th) until the input current (2) falls below the set value (2). When the input current (■) becomes less than the set value (■2), the operating frequency F at that time is held.

After that, due to load fluctuations, etc., the input current ■ changes to the set value I2.
Even if the operating frequency F exceeds the
Decrease step by step. Then, when the input current {circle around (2)} decreases to the set value 11, the operating frequency F is set to a value corresponding to the total air conditioning load of each indoor unit.

[Problems with background technology]

However, since the set value P2 is determined based on the maximum load of the compressor, if the number of indoor units in operation is small and the operating frequency F of the compressor is relatively low, the high pressure side pressure may rise abnormally. However, the input current I may not exceed the set value P2, and the high voltage switch may operate without the operation frequency control as described above working.

[Purpose of the invention]

This invention was made in view of the above circumstances,
The purpose of this is to reliably suppress abnormal increases in pressure on the high pressure side without being affected by the number of indoor units in operation or the operating frequency of the compressor, thereby preventing unnecessary operation stoppages. Our goal is to provide an air conditioner with excellent reliability.

[Summary of the invention]

This invention includes a variable capacity compressor, a four-way valve, an outdoor heat exchanger,
An air conditioner comprising a heat pump refrigeration cycle formed by sequentially communicating a pressure reducing device, a plurality of indoor heat exchangers, etc., and controlling the operating frequency of the compressor according to the total air conditioning load of each indoor heat exchanger, means for detecting refrigerant pressure at a collection point of gas side refrigerant branch pipes of each indoor heat exchanger;
Means is provided for controlling the operating frequency of the compressor so that the detected pressure does not exceed a set value during heating operation.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, O is an outdoor unit, H is a branch unit, and A, B, and C are indoor units.

Reference numeral 1 denotes a variable capacity compressor whose capacity changes depending on the frequency (and voltage) of the power supplied from the inverter circuit 2 . Thus, the compressor 1, the four-way valve 3, the outdoor heat exchanger 4, the parallel body of the heating expansion valve 5 and the check valve 6, the parallel body of the indoor heat exchangers 7a, 7b, and 7c, the accumulator 8, etc. They are connected to form a heat pump refrigeration cycle.

Then, the electric flow rate adjustment valve '+2a and the cooling cabillary tube 13a are sequentially inserted into the oil side refrigerant branch pipe 11a of the indoor heat exchanger 7a, and the electric flow rate adjustment valve '+2a is connected to the oil side refrigerant branch pipe 11b of the indoor heat exchanger 7b. 12b and the cooling capillary tube 13b are sequentially inserted, and the electric flow rate adjustment valve 12c and the cooling capillary tube 13c are sequentially inserted into the oil side refrigerant branch pipe 11c of the indoor heat exchanger 7C. In addition, an electromagnetic on-off valve 15a is inserted into the gas-side refrigerant branch pipe 14a of the indoor heat exchanger 7a, an electromagnetic on-off valve 15b is inserted into the gas-side refrigerant branch pipe 14b of the indoor heat exchanger 7b, and the
An electromagnetic on-off valve 15c is inserted into the gas side refrigerant branch pipe 14c.

Furthermore, the oil side refrigerant branch pipe 11a in the branch unit H
, 11b, and 11C and each cooling capillary tube, one end of the refrigerant recovery piping 20 is connected to each other, and the other end of the refrigerant recovery piping 20 is connected to the four-way valve in the outdoor unit 0. 3 and accumulator 8
is connected between. In the refrigerant recovery pipe 20, a resistor 2 is provided in the part communicating with the oil side refrigerant branch pipe 11a.
1a and the electromagnetic on-off valve 22a are sequentially inserted, the resistor 21b and the electromagnetic on-off valve 22b are sequentially inserted in the part communicating with the oil-side refrigerant branch pipe 11b, and the resistor 21c and the electromagnetic on-off valve 22b are inserted in the part communicating with the oil-side refrigerant branch pipe 110. The valves 22c are sequentially inserted and connected.

Then, in the branch unit H, the gas side refrigerant branch pipe 14
A pressure sensor 30 for detecting refrigerant pressure is attached to the collecting part of a, 14b, and 14c.

Note that indoor units A, B, and C each have their own indoor temperature (
or intake air temperature) sensor. Moreover, the illustrated solid line indicates the refrigerant flow direction during the cooling operation, and the illustrated broken line arrow indicates the refrigerant flow direction during the heating operation due to the switching operation of the four-way valve 3.

FIG. 2 shows the control circuit.

An outdoor controller 40 is provided in the outdoor unit O, and the inverter circuit 2 is connected to this outdoor controller 40. The outdoor controller 40 consists of a microcomputer and its peripheral circuits.

In the branch unit H, a multi-controller 50 is provided, and the pressure sensor 30 is connected to the multi-controller 50.
and valve drive circuits 51a, 51b, 51c.

52a, 52b, and 52c are connected. here,
The multi-controller 50 is composed of a microcomputer and its peripheral circuits, and is configured to supply various control commands to the outdoor controller 40 in the form of serial signals. The valve drive circuits 51a, 51b, and 51c drive the electric flow rate regulating valves 12a, 12b, and 12c, respectively. Valve drive circuit 52a,
52b and 52c are the electromagnetic on-off valves 15a and 15
b and 15c, respectively.

Indoor controllers 60a for indoor units A, B, and C,
60b, 60c are provided, and operation control units 61a, 61b, 61c and indoor temperature sensors 62a, 62b, 62c are connected to these indoor controllers. Here, the indoor controllers 60a, 60b,
60c consists of a microcomputer and its peripheral circuits, and is configured to supply various control commands to the multi-controller 50 in the form of serial signals.

Next, the operation in the above configuration will be explained.

Now, use the operation section 61a of the indoor unit A to set the heating operation and desired indoor temperature, and perform an operation to start the operation.

Then, the indoor controller 60a detects the indoor humidity sensor 62.
The difference between the detected temperature a and the set temperature is calculated, and the operating frequency setting command f1 and heating operation command corresponding to the temperature difference are transferred to the multi-controller 50.

Further, the heating operation and desired indoor temperature are set using the operation section 61b of the indoor unit B, and an operation start operation is performed.

Then, the indoor controller 60b detects the indoor temperature sensor 62.
The difference between the detected temperature b and the set temperature is calculated, and the operation frequency setting command f2 and heating operation command corresponding to the concentration difference are transferred to the multi-controller 50.

The multi-controller 50 responds to the heating operation commands from the indoor units A and B, and transfers the heating operation command and the operating frequency setting command f to the outdoor controller 40. This operating frequency setting command f.

corresponds to the sum of the contents of the operating frequencies f1 and f2.

Further, the multi-controller 50 controls the electric flow rate regulating valve 12a by the valve drive circuit 51a with an operating frequency setting command f,
The valve drive circuit 52a is set to the opening degree corresponding to the valve drive circuit 52a.
This causes the electromagnetic on-off valve 15a to open. Further, the multi-controller 50 uses the valve drive circuit 51b to set the electric flow rate adjustment valve 1211 to an opening corresponding to the operating frequency setting command f2, and causes the valve drive circuit 52b to open the electromagnetic on-off valve 15b.

The outdoor controller 40 switches the four-way valve 3 in response to the heating operation command, and also receives the operation frequency setting command f,
The inverter circuit 2 outputs power at a frequency corresponding to the frequency, and the compressor 1 is started.

At this time, the electromagnetic on-off valve 15a is in the open state and the electric flow rate adjustment valve 12a is opened to a predetermined opening degree, so that the refrigerant discharged from the compressor 1 circulates through the indoor heat exchanger 7a. At the same time, the electromagnetic on-off valve 15b is in an open state, and the electric flow rate adjustment valve 12b is opened to a predetermined opening degree, so that the refrigerant circulates through the indoor heat exchanger 7b. The refrigerant flowing into the indoor heat exchangers 7a and 7b loses heat to the indoor air and condenses. That is, heating operation is started in indoor units A and B. In this case, compression! The operating frequency F (output frequency of the inverter circuit 2) of 111 corresponds to the total air conditioning load of the indoor units A and B, and the opening degree of the electric flow regulator valves 12a and 12b corresponds to the air conditioning load of the indoor units A and B. Each corresponds to the load, so that indoor units A and B can perform optimal heating operation.

During this heating operation, the multi-controller 50 detects the pressure detected by the pressure sensor 30, that is, the gas side refrigerant branch pipe 14a.

The refrigerant pressure P (high pressure side pressure) at the gathering part of 14b and 14c is monitored, and the third
The operating frequency control shown in Figs. and 4 is performed.

That is, at the start of heating operation, the operating frequency F of the compressor 1
increases from the lowest operating frequency toward the target value corresponding to the total air conditioning load of each indoor unit, but if the refrigerant pressure P exceeds the set value P2 at that time, the operating frequency F is increased by one step (for example, 5 Hz). When the refrigerant pressure P becomes lower than the set value P2, the operating frequency F at that time is maintained. Thereafter, even if the refrigerant pressure P exceeds the set value P2 due to load fluctuations or the like, the operating frequency F is lowered one step at a time until the refrigerant pressure P becomes lower than the set value P2. Then, the refrigerant pressure P is the set value P! When the air conditioning load decreases to 1, the operating frequency F is set to a value corresponding to the total air conditioning load of each indoor unit.

In this way, the refrigerant pressure P, which is the high-pressure side pressure, is directly detected and the operating frequency F of the compressor 1 is controlled so that the refrigerant pressure P does not exceed the set value 12. At the start of operation, even if the number of indoor units in operation is one and the operating frequency F of the compressor 1 is relatively low, an abnormal increase in the pressure on the high pressure side can be reliably suppressed. Therefore, unnecessary stoppage of operation due to the actuation of the high-pressure switch 9 can be prevented, and reliability can be improved. Furthermore, unnecessary shutdowns can be prevented not only when heating operation is started but also when the number of operating indoor units changes.

In the above embodiment, each indoor controller issues the operating frequency commands f1, f2, and f3.
The indoor controller may emit only a temperature difference signal corresponding to the temperature difference, and the determination of the operating frequency according to the temperature difference may be performed only by the multi-controller 50. Furthermore, although the case where there are three indoor units has been described, there is no limitation to the number of indoor units.

〔Effect of the invention〕

As described above, according to the present invention, a means is provided for detecting the refrigerant pressure at the collecting part of the gas side refrigerant branch pipes of each indoor heat exchanger, and the compressor is compressed so that the detected pressure does not exceed a set value during heating operation. Since we have provided a means to control the operating frequency of the compressor, it is possible to reliably suppress abnormal increases in pressure on the high pressure side without being affected by the number of operating indoor units or the operating frequency of the compressor. It is possible to provide a highly reliable air conditioner that can prevent operation stoppages.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a refrigeration cycle in one embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a control circuit in the same embodiment, and FIG. 3 is a diagram showing the operating frequency control in one embodiment of the present invention. FIG. 4 is a flow chart for explaining the relationship between refrigerant pressure and operating frequency control in the same embodiment, and FIG. 5 is a diagram for explaining operating frequency control in a conventional air conditioner. O...Outdoor unit, H...Branch unit, A, B
. C...Indoor unit, 1...Variable capacity compressor, 3.
...Four-way valve, 4...Outdoor heat exchanger, 7a, 7b,
7c...Indoor heat exchanger, 14a, 14b, 1
4c...Gas side refrigerant branch pipe, 50...Multi controller.

Claims (1)

[Claims] A heat pump type refrigeration cycle is provided in which a variable capacity compressor, a four-way valve, an outdoor heat exchanger, a pressure reducing device, a plurality of indoor heat exchangers, etc. are connected in sequence, and the above-mentioned In an air conditioner that controls the operating frequency of a compressor, means for detecting refrigerant pressure at a gathering part of gas side refrigerant branch pipes of each indoor heat exchanger, and during heating operation;
An air conditioner comprising means for controlling an operating frequency of the compressor so that the detected pressure does not exceed a set value.