JPH0788954B2 - Defrost control device for air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a defrosting control device for an air conditioner, which is adapted to prevent a defrosting failure of a direct expansion type air conditioner that performs heating operation, for example. It is a thing.

[Conventional technology]

FIG. 5 is a block diagram of a conventional defrost control device for an outdoor unit of an air conditioner, in which 1 is a temperature-voltage conversion circuit, 2 is a defrost start thermostat, and 3 is a defrost end thermostat.

The output of the temperature-voltage conversion circuit 1 is sent to the defrost start thermostat 2 and the defrost end thermostat 3, the defrost holding memory 4 is set by the output of the defrost start thermostat 2, and the output of the defrost end thermostat 3 is removed. The frost holding memory 4 is reset.

The defrost forced termination timer 5 prevents defrost from extending for a long time, and its output is sent to the defrost holding memory 4 and reset.

The defrosting prohibition timer 6 prohibits the defrosting operation for 60 minutes after the defrosting and after the power is turned on, and the contact drive circuit 7 and the defrosting forced termination timer 5 are reset by the output thereof.

The output of the defrost holding memory 4 is input to the contact drive circuit 7. The contact drive circuit 7 outputs a defrost signal.

Next, the operation will be described. The temperature-voltage conversion circuit 1 is
Detects the piping temperature of the outdoor unit and converts it into voltage. When the output voltage of the temperature-voltage conversion circuit 1 is applied to the defrosting start thermostat 2 and the defrosting end thermostat 3, and this voltage becomes a voltage corresponding to the defrosting start temperature, the defrosting start thermostat 2 is stored in the defrost holding memory 4 A set signal is output to, the output of the defrost holding memory 4 is turned on, and the contact drive circuit 7 is turned on.

Next, when the pipe temperature rises and reaches the temperature at which defrosting is finished, the defrosting end thermostat 3 resets the defrosting holding memory 4, turns off the output of the defrosting holding memory 4, and defrosts it. The prohibit timer 6 is reset. The reset defrosting prohibition timer 6 outputs “OFF” for 60 minutes to prohibit defrosting.

Further, the defrost forced termination timer 5 starts the conversion of the timer by the defrost start signal, and when the time is up (about 15 minutes), the defrost holding memory 4 and the defrost prohibition timer 6 are reset to terminate the defrost. .

The defrost forced termination timer 5 is reset by the defrost termination signal.

[Problems to be solved by the invention]

Since the conventional defrost control device for an outdoor unit of an air conditioner is configured as described above, the high-pressure-side liquid refrigerant rapidly flows into the pipe of the outdoor unit at the start of the defrosting operation. Although the pipe temperature rises as shown in the figure, the defrosting termination thermostat 3 operates due to such a temporary temperature rise, and the defrosting prohibition timer 6 is reset, so that defrosting is in an insufficient state. Nevertheless, the defrosting ends and the defrosting prohibition mode is set.

For this reason, defrosting becomes poor, which causes non-heating, pipe breakage, and the like, which significantly reduces the reliability of the system.

The present invention has been made in order to solve such a problem, and has a simple circuit configuration, and even if the pipe temperature rises for a few minutes after the start of defrosting, defrosting is not terminated and an appropriate value can be obtained. An object is to obtain a defrost control device for an air conditioner that can perform a defrost operation.

[Means for solving problems]

In order to achieve the above object, a temperature-voltage conversion circuit that detects the pipe temperature of the refrigerant circuit of the air conditioner, a defrost start thermostat that outputs an output when the pipe temperature reaches the defrost start temperature, and the pipe temperature ends defrost. Defrost end thermometer that outputs when temperature reaches, defrost holding memory that is set by the output of the defrost start thermometer and is reset by the output of the defrost end thermometer, when this defrost holding memory is set A driving means for terminating the defrosting operation when the defrosting holding memory is reset while starting the defrosting operation on
A defrost forced termination timer that resets the defrost holding memory after a predetermined time after the start of defrost, a prescribed time after power-on, and a prescribed time after being reset by the output of the defrost termination thermostat or the defrost forced termination timer In a defrosting control device for an air conditioner having a defrosting prohibition timer that prohibits the defrosting start operation of the driving means, in the defrosting state for several minutes after the defrosting starts, even if the pipe temperature reaches the defrosting end temperature. It is intended to provide a defrost control device for an air conditioner, which is provided with a defrost holding timer that stops the operation of the defrost end thermostat in order to hold the above.

[Work]

In the present invention, the defrost holding timer 8 is activated by the output of the defrost forced termination timer to prevent the defrost termination thermostat from operating for several minutes after the start of the defrosting operation, and the defrosting is performed by the rapid inflow of the liquid refrigerant. Prevents defrosting from being terminated despite insufficient frost.

〔Example〕

An embodiment of a defrost control device for an air conditioner according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment thereof. In FIG. 1, parts 1 to 7 are exactly the same as those in the conventional example.

In the present invention, the defrost holding timer 8 is newly added to the configuration of FIG. The defrost hold timer 8 receives the frequency-divided output of the defrost control end timer 5 after the defrost starts and stops the operation of the defrost end thermostat 3 for several minutes.

That is, the defrost hold timer 8 is set by the output of the defrost forced termination timer 5, and is reset by the output of the defrost hold memory 4.

The concrete circuit configuration of the defrost holding timer 8 is shown in FIG. 2, and FIGS. 3 (a) to 3 (e) are time charts showing the operation.

In FIG. 2, the output of the defrost forced termination timer 5 in FIG. 1 is input to the input terminal T1.
The input terminal T1 is connected to the power supply via the resistor R1 and is also connected to the base of the transistor Q1 via the resistor R2.

A resistor R3 is connected between the base and the emitter of the transistor Q1, and the emitter is grounded. The collector of the transistor Q1 is connected to the power supply via the resistor R4 and the comparator via the diode D1 and the resistor 9.
It is connected to the (+) input terminal of 11.

The (+) input terminal of the comparator 11 is grounded via the capacitor 10, and the connection point between the resistor 9 and the capacitor 10 is connected to the terminal T3 via the diode D2. Terminal T3
A reset signal from the defrost holding memory 4 shown in FIG. 1 is input to.

The time constant of the CR timer is determined by the resistor 9 and the capacitor 10. The comparator 11 detects the voltage of the CR timer and sends the defrost hold output to the output terminal T2 via the diode D3. Is.

The (−) input terminal of the comparator 11 is connected to the connection point between the resistors R5 and R6. The series circuit of the resistors R5 and R6 is connected between the power supply and ground. A reference voltage is applied to the (−) input terminal of the comparator 11 by the resistors R5 and R6.

Next, the operation of the present invention will be described. Defrost output (defrost signal) shown in Fig. 3 (a) from the moment the defrost starts
Becomes "H", and at the same time, as shown in FIG. 3 (e), defrosting is started, and the capacitor 10 passes through the resistor R4, the diode D1, and the resistor 9 from the power source, as shown in FIG. 3 (c). Charging is started with a time constant determined by the resistors R4, 9 and the capacitor 10.

Further, the input terminal T1 of the defrost holding timer 8 is divided into 8/15 (2
(A little less than a minute), signals of "L" and "H" are input, whereby the charging voltage of the capacitor 10 is charged with a rest time of less than one minute. A resistor that determines this voltage in advance
By comparing with the comparator 11 the reference voltage divided by R5 and R6, the capacitor 10
The charging voltage becomes higher than the reference voltage, and as shown in FIG. 3 (d), the output of the comparator 11 passes from the diode D3 to the output terminal T2, and the output of the defrost holding timer 8 changes from "L" to "H". ", And the defrosting end thermostat 3 is reset to return to normal operation.

When the defrosting ends, the output of the defrosting memory 4 is added to the terminal T3 of the defrosting holding timer 8, the defrosting holding timer 8 is reset, and the capacitor 10 is discharged.

By configuring the circuit as described above, FIG.
As shown in FIG.
Since it does not operate for a minute, defrost does not end due to a temporary rise in pipe temperature due to a sudden flow of liquid refrigerant (hot gas) into the outdoor unit pipe during the initial defrost period, ensuring sufficient defrost time. It does not cause defrosting failure.

In the above embodiment, the defrost holding timer is a CR timer, but other timers, ICs, etc. may be used.

In the above embodiment, the defrost control device for the outdoor unit when the air conditioner is heated has been described, but it is also effective for defrosting the low-pressure refrigerant circuit of the hot water source such as the chilling unit.

〔The invention's effect〕

As described above, the pipe temperature temporarily rises, and the defrosting ends due to the defrosting thermostat, but the pipe temperature reaches a predetermined return temperature for a few minutes after the defrosting operation starts. Even so, since the defrost holding timer for holding the defrost state is provided, it is possible to perform sufficient defrost by adding a simple defrost holding timer to the configuration of the conventional device, and it is possible to prevent defrosting due to insufficient defrosting. It is possible to prevent warming, high pressure cutting, and breakage of piping, and it is possible to obtain a highly reliable system.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a defrost control device for an air conditioner according to the present invention, FIG. 2 is a circuit diagram showing a specific circuit configuration of a defrost hold timer, and FIG. 3 is the same defrost hold timer. 4 is a time chart for explaining the operation of FIG. 4, FIG. 4 is a pipe temperature characteristic diagram during defrosting, and FIG. 5 is a block diagram of a conventional defrosting control apparatus for an outdoor unit of an air conditioner. 1 ... Temperature-voltage converter, 2 ... Defrost start thermostat, 3 ...
... Defrost end thermostat, 4 ... Defrost hold memory, 5 ... Defrost forced end timer, 6 ... Defrost prohibit timer, 7 ... Contact drive circuit, 8 ... Defrost hold timer, 9 ... Resistor , 10 …… capacitor, 11 …… comparator. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Unexamined Patent Publication No. 52-65343 (JP, A) Actually opened 52-118263 (JP, U) Actually opened 53-134248 (JP, U)

Claims (2)

[Claims] 1. A temperature-voltage conversion circuit for detecting a pipe temperature of a refrigerant circuit of an air conditioner, a defrost start thermostat which outputs an output when the pipe temperature reaches a defrost start temperature, and a pipe temperature reaches a defrost end temperature. Defrost ending thermometer that outputs an output, defrost holding memory that is set by the output of the defrost starting thermometer and is reset by the output of the defrost ending thermometer, defrosting when this defrost holding memory is set Driving means for starting the operation and ending the defrosting operation when the defrost holding memory is reset, a defrost forced termination timer for resetting the defrost holding memory after a predetermined time after the start of defrosting, after turning on the power Defrost prohibition tie for prohibiting the defrosting start operation of the drive means for a predetermined time and for a predetermined time after being reset by the output of the defrosting end thermostat or the defrosting forced end timer. In the defrosting control device after air conditioning having the above, the operation of the defrosting termination thermostat is stopped for several minutes after the defrosting is started in order to maintain the defrosting state even when the pipe temperature reaches the defrosting termination temperature. A defrost control device for an air conditioner, which includes a defrost holding timer. 2. A defrosting control device for an air conditioner according to claim 1, wherein the defrosting holding timer comprises a CR timer composed of a resistor and a capacitor.