JPS63238365A - Protective device for 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 (a) Field of Industrial Application The present invention relates to a protection device for an air conditioner, and particularly to prevention of burnout of a compressor due to startup failure.

(b) Conventional technology In general, the permissible current of the stator winding of a compressor is determined by the thickness of the steel wire used, and if a current exceeding this permissible current flows continuously for a predetermined period of time or more, the stator winding becomes fixed. The child winding was sometimes burnt out. This type of overcurrent flows mainly when the compressor is locked or overloaded, and it is common practice to detect this overcurrent and stop the compressor. Met.

However, such overcurrents can also flow for a short time, such as when the compressor starts up or during short-term load fluctuations, and these currents may be detected and erroneously implemented protection. Therefore, methods such as those described in Japanese Utility Model Publication No. 57-39714 and Japanese Utility Model Publication No. 58-38344 were attempted. What is not listed in these bulletins is
An automatic reset type thermal relay was used, and the bimetal of this relay was installed in the wiring that supplied power to the compressor, and the relay for power supply was controlled through the contact that was activated by the heat generated by this bimetal. This thermal response time of the bimetal was used to prevent the compressor from stopping due to false protection caused by an overcurrent flowing in a short period of time.

(C) Problems to be Solved by the Invention The protection device configured as described above cannot sufficiently prevent malfunctions.

For example, overcurrent flows to the compressor not only in the above cases, but also when there is a large difference in refrigerant pressure between high and low pressures in the refrigerant circuit, the condition is essentially the same as when the compressor is locked. As a result, excessive current continued to flow through the compressor. In the conventional technology as described above, the protection device operates even in such a case, and the compressor and air conditioner are stopped.

However, the situation where there is simply a difference in refrigerant pressure between high and low pressures in the refrigerant circuit is not an abnormal state as long as this difference in high and low pressures is balanced, and conventional technology has the problem of going into protective operation even in such cases. had.

In view of such problems, the present invention provides a protection device that suppresses such malfunctions.

(d) Means for Solving the Problems The present invention provides a refrigeration cycle in which a compressor, a condenser, a pressure reducing device, and an evaporator are connected in a circular manner via refrigerant piping, and a high-pressure side and a low-pressure side of the compressor. A protection device for an air conditioner that has a bypass pipe that is connected between the compressor and can be opened and closed, and includes a current detection section that detects the current flowing through the compressor, and a signal that outputs a signal when the detected value of the current detection section is equal to or higher than a reference value. A comparison section, a timer section that outputs a signal after the signal of this comparison section is maintained for a predetermined time, and the first output from this timer section stops the compressor for a certain period of time and keeps the bypass pipe open. and a display section that displays an alarm in response to a plurality of outputs from the timer section.

(*) In a protective device configured in this way, if an overcurrent flows during startup when there is still a large difference in refrigerant pressure within the refrigeration cycle, the comparator determines the first overcurrent condition. Then, the control section opens the bypass pipe and stops the compressor.
It is possible to balance high and low pressure within the refrigeration cycle during a certain period of time. The compressor starts normally by restarting the compressor after a certain period of time.

(f) Examples Examples of the present invention will now be described based on the drawings. In the refrigerant circuit diagram shown in Figure 1, 1 is a pole converter compressor that can be switched between two poles and four poles, 2 is a four-way switching valve that can be switched between a cooling (defrosting) cycle and a heating cycle, and 3 is an outdoor heat Exchanger, 4 is an expansion valve for heating and cooling, 5 is a check valve, 6 is a capillary tube for cooling, 7 is a refrigerant adjustment container, 8 is a gas-liquid separator, 9 is a compressor 1
The discharge pipe 10 and the suction pipe 11 are straddled over.
A first bypass pipe 14 is connected in parallel with this capillary 13 and is provided with a first valve 12 and a first capillary 13 in order from the side, which are opened during overload operation, anti-freezing, and peak switching of the compressor 1. A second bypass pipe is provided with a check valve 15 and a second valve 16 that opens when the number of poles of the compressor 1 is changed from the first valve 12 side, one end of which is connected to the outdoor heat exchanger 3 during the defrosting cycle. The other end is a second capillary tube connected between the check valve 15 and the second valve 16, and these devices are built into one outdoor unit 19. .

20a and 20b are respectively cooling on/off valves 21a, 21b, check valves 22a, 22b, cooling capillary tubes 23m, 23b, heating on/off valves 24a, 24b, % check valves 25a,
25b, indoor heat exchanger 26a, 26b, heating on-off valve 2
4a, 24b and indoor heat exchangers 26a, 26b, and is connected in parallel to the outdoor unit 19 as shown.

During simultaneous heating operation of both indoor units 20a and 20b, the heating on-off valves 24a and 24b are opened, the four-way switching valve 2 is set to the solid line state, and the compressor 1 is started to operate, and the refrigerant discharged from the compressor 1 is are four-way switching valve 2 - indoor heat exchangers 26a, 26b - heating on-off valves 24a, 24b -
Check valves 25a, 25b - Refrigerant adjustment container 7 - Expansion valve 4 - Outdoor heat exchanger 3 - Four-way switching valve 2 - Gas-liquid separator 8 - Compressor 1
A two-unit heating cycle is formed.

During simultaneous cooling operation of both indoor units 20a and 20b, the cooling on-off valves 21a and 21b are opened, the four-way switching valve 2 is set to the dotted line state, the compressor 1 is started, and the refrigerant discharged from the compressor 1 is Four-way switching valve 2 - outdoor heat exchanger 3 - expansion valve 4, check valve 5, cooling capillary 6 - refrigerant adjustment container 7 - cooling on/off valves 21a, 21b - check valve 22
a, 22b - cooling capillary tubes 23a, 23b - indoor heat exchangers 26a, 26b - four-way switching valve 2 - gas-liquid separator 8 and compressor 1, forming a two-unit cooling cycle.

FIG. 2 is an electrical circuit diagram of a main part used in the refrigerant circuit shown in FIG. 1. Compressor 1 in the figure. The four-way switching valve 2 and the valve 12 are given the same reference numerals to correspond to each other. Although the compressor 1 is shown as a single-phase compressor in the circuit diagram, it may also be a three-phase compressor that switches between two poles and four poles. In this state, the flow path is in the state shown by the solid line in FIG. In other words, it is in a heating operation state. Mataben 12
It is also electrically powered and opens when energized.

Compressor 1 2-pole operating terminal, 4-pole operating terminal, 4-way switching valve 2
, the valves 12 are connected to the alternating current power supply via normally open segments 28 to 31, respectively. These normally open contacts 28 to 31 are closed by energization of relays 32 to 35, respectively. The relays 32 to 35 are connected to the microcontroller 37 via the buffer 36.
It is connected to terminals D2゜Di, CI, and CI.

38 is a comparator that provides an output to terminal B3 of the microcomputer 37, one input terminal is applied with a reference voltage determined by resistors 39 and 40, and the other input terminal is applied with a current transformer (C, T) 41. Heavy pressure is applied by rectifying and smoothing the induced alternating current voltage. 42 and 43 are diodes and capacitors, which together with resistors 44 and 45 and 46 constitute a rectifying and smoothing circuit section. The current transformer 41 is installed so that the current flowing through the compressor 1 can be detected.

In addition, in the case of a single-phase compressor, it is sufficient to detect the entire current, and in the case of a three-phase compressor, it is sufficient to detect the current flowing in any one phase.

Therefore, the output of the comparator 38 changes from an H (high) level voltage to a low (low) level voltage when the voltage applied to the other input terminal exceeds the reference voltage applied to one input terminal. That is, when the current value detected by the current transformer 41 exceeds the current value corresponding to the reference voltage (at the time of overcurrent), the output of the comparator 38 becomes an L level voltage.

Reference numerals 47 and 48 indicate operation units provided in the indoor units 20a and 20b, respectively, and terminals AO and AO of the microcomputer 37 are connected via photocouplers 49 and 50 and transistors 51 and 52, respectively.
Connected to AI.

Note that 53.54 is the load resistance. This operating section 47.4
8 is the same indoor unit 20a, 20.
It is used near b. For example, from the operation section 47,
An operation/stop signal for the indoor unit 20a, a cooling/heating signal, a thermo signal obtained from the difference between the room temperature and a set value, and the like are transmitted. Based on this thermo signal, the compressor 1 is operated/stopped and switched between two poles and four poles.

Note that 55 is a warning light that lights up in the event of an abnormality.

FIG. 3 is a flowchart showing the main operations of the microcomputer 37 shown in the electrical circuit diagram of FIG. The main operation of this flowchart is to perform startup processing in step S1.

At this time, the timer starts counting. In this embodiment, the timer is set to about 1 minute. In step S2, various operating signals from the operating units 47 and 48 are input. In step S3, it is determined whether the compressor 1 is to be operated in two poles (2P) or four poles (4P). If a signal for four-pole (4P) operation is output, the process goes to step S4, and if a signal for two-pole (2P) operation is output, the process goes to step S5. If neither the two-pole nor the four-pole operation signal is output, a stop process is performed in step S6.

At this time, if the stopped state has not passed for more than one minute, the timer is started.

In step S4, if the compressor 1 is currently performing two-pole (2P) operation, the compression ml operation is stopped, the valve 12 is opened, and the timer is started.

As a result, the operation of step S2 is repeated until the time is up. Steps S3 to 4 even after the time is up.
If the pole (4P) operation signal is maintained, step S7
, S8, the compressor 1 is operated at four poles (4P) and the valve 12 is closed. In addition, going to step S7 in step S4 is as follows.
These are when the compressor 1 is in two-pole (2P) operation and when the compressor 1 is stopped.

When the compressor 1 is performing four-pole (4P) operation in step S5 and the F flag is F-1, the operation in step S9 is performed. In step S9, the four-pole (4P) operation is maintained, the valve 12 is opened, F-1 is set, and the timer is started. Therefore, while the timer is measuring time, the
Polar (4P) operation is maintained. After the timer expires, the state is F-1, so step SIO is performed. At this time, if the current transformer 41 shown in FIG.
P), close valve 12, and set F flag and T flag to F-
0, T-0. This step S10 is step S10.
It is also executed when the compressor 1 is stopped in step 5 or when it is in two-pole (2P) operation. If the overcurrent continues to flow for 2 seconds during the execution of step S10, step Sll is executed. In other words, if the T flag is T≠1, the compressor 1
operation is stopped, valve 12 is opened, a timer is started, and the T flag is set to T-1. As a result, the valve 12 is opened for one minute until the time is up to balance the refrigerant pressure, and then the two-pole (2P) operation is started again. When the overcurrent is maintained for 2 seconds or more again at the time of restart (T flag -1), step S12 is executed.

That is, after the warning light 55 shown in FIG. 2 is turned on for one minute, it returns to the initial state.

FIG. 4 is a time chart showing the operation when using the air conditioner configured as described above.

First, the power is turned on at time t. The valve 12 is opened for 1 minute until 1+ to balance the refrigerant pressure in the refrigeration cycle. At time tl, a signal for 4-pole (4P) operation is issued and the compressor is started. This special rush current flows for about 0.2 to 0.3 seconds. Then t.

When a signal to switch from 4-pole (4P) operation to 2-pole (2P) operation is output at time t, the valve 12 is opened from time t to time t4 to reduce the high and low pressure difference in the refrigeration cycle. Make it smaller. Switching to two-pole (2P) operation starts at time t4. When 2-pole (2P) operation is stopped at time t, t
, ~t, are opened to measure the pressure balance. t,
When a signal to switch from two-pole (2P) operation to four-pole (4P) operation is issued at time t, compressor operation is stopped until time t, and valve 12 is opened to reduce the refrigerant pressure in the refrigeration cycle. balance. After this, the compressor is started in 4-pole (4P) operation.

Next, when the 2-pole (2P) operation signal comes out at time tlm,
If the pressure within the refrigeration cycle is not sufficiently balanced due to compressor failure or changes in outside temperature, an overcurrent will flow as shown in Figure 4. This overcurrent is about 2 from tlm to tlm.
When it flows for seconds, the compressor is stopped for 1 minute from tl to tl, and the valve 12 is opened to balance the pressure in the refrigeration cycle. Thereafter, at time t4, the compressor is started again in two-pole (2P) operation. At this time, if the overcurrent flows again for about 2 seconds, the compressor is stopped and an alarm is displayed.

Incidentally, if the operating current is normal at the time of tti, the two-pole (2P) operation is maintained as it is.

In this way, in the above embodiment, when switching the number of operating poles of the compressor from 2 to 4 poles or from 4 to 2 poles, the valve is opened and the bypass pipe is opened to operate the refrigeration cycle. It is possible to quickly balance high and low pressure within the body. Furthermore, when switching from four poles to two poles, the number of poles can be changed without stopping the compressor, and the range of temperature fluctuations in the conditioned room can be reduced.

In addition, even if an overcurrent flows when the compressor is started, the alarm display does not activate immediately; instead, the restart is performed after the refrigerant pressure in the refrigeration cycle is balanced, so that overcurrent does not occur. If the cause of the current flow is due to the high-low pressure difference within the refrigeration cycle, the overcurrent will not flow again. That is,
This can suppress erroneous display of 5 reports.

(G) Effects of the Invention The present invention achieved as described above detects the current flowing through the compressor with the current detection section, and this detected value becomes an overcurrent value that is higher than the reference value, and this overcurrent state After the time is maintained, the bypass pipe is opened for a certain period of time and the compressor is stopped, so that the difference in high and low pressures within the refrigeration cycle can be reduced. Therefore, if the cause of the overcurrent flowing in the compressor is that the compressor is locked due to the difference in high and low pressure remaining in the refrigeration cycle, then the overcurrent flows in the refrigeration cycle during this certain period of time. The pressure difference can be balanced and the compressor can be started normally after this certain period of time. Additionally, if the cause of excessive current flowing through the compressor is due to other causes, an alarm will be displayed after the above operations have been performed multiple times.

In other words, it can prevent the malfunction of the protective device in the event of an overcurrent caused by the difference in high and low pressure remaining within the refrigeration cycle.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram showing a refrigeration cycle using an embodiment of the present invention, Fig. 2 shows the operation of the refrigerant shown in Fig. 1, and Fig. 4 shows the operation of the compressor and valves shown in Fig. 1. This is a time chart. 1... Compressor, 2... Four-way switching valve, 12...
Valve, 37...Microcomputer, 41...Current transformer, 55...Warning light.

Claims (1)

[Claims] (1) A refrigeration cycle in which a compressor, a condenser, a pressure reducer, and an evaporator are sequentially connected in a ring through refrigerant piping, and a bypass pipe that is connected between the high-pressure side and the low-pressure side of the compressor and that can be opened and closed. A protection device for an air conditioner has a current detection section that detects the current flowing through the compressor, a comparison section that outputs a signal when the detected value of the current detection section is equal to or higher than a reference value, and a signal of the comparison section that outputs a signal for a predetermined period of time. a timer section that outputs a signal after the signal is maintained; a first control section that stops the compressor for a certain period of time and opens the bypass pipe according to the first output from the timer section; and the timer section. 1. A protection device for an air conditioner, comprising: a display section that displays an alarm upon multiple outputs from the air conditioner.