JPS63140237A - Defrosting controller for air conditioner - Google Patents

Abstract

PURPOSE:To prevent failure in heating or breakage of a piping system from occurring due to insufficient defrosting and enhance reliability, by providing a defrosting-maintaining timer for maintaining a defrosting condition for a period of several minutes after the start of a defrosting operation, even when the temperature of the piping system becomes equal to a predetermined reset temperature. CONSTITUTION:The moment defrosting is started, a defrosting output shown in diagram (a) becomes 'H'. Also, simultaneously when the defrosting is started as shown in diagram (e), charging of a capacitor 10 is started. An input terminal T1 of a defrosting-maintaining timer 8 is supplied with an 'L'-'H' signal having a divided period of 15/8min (slightly less than 2min), shown in diagram (b), from a timer 5 for forced finishing of defrosting, whereby the charged voltage of the capacitance 10 is increased, with rest periods of slightly less than 1min. The charged voltage of the capacitor 10 exceeds a reference voltage after about 2.5min from the start of defrosting. Thus, as shown in diagram (d), an output from a comparator 11 sent through a diode D3 to appear at an output terminal T2 as an output from the timer 8 is changed from 'L' to 'H', whereby a defrosting-finishing thermostat 3 is reset for returning to a normal operation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a defrosting control device for an air conditioner, which prevents defrosting failure in a direct expansion type air conditioner that performs heating operation, for example. It is something.

[Conventional technology]

Fig. 5 is a block diagram of a conventional defrosting control device for an outdoor unit of an air conditioner. In the figure, 1 is a fan degree-to-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 defrost end thermostat 3, and the output of the defrost start thermostat 2 sets the defrost holding memory 4, and the output of the defrost end thermostat 3 sets the defrost hold memory 4. I am trying to maintain frost and reset memory 4.

The defrost compulsory end timer 5 prevents defrosting from extending over a long period of time, and its output is sent to the defrost holding memory 4 and reset.

The defrost prohibition timer 6 prohibits the defrost TJ operation for 60 minutes after the defrost ends and when the power is turned on, and the defrost compulsory timer 5 is reset with its output.

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

Next, the operation will be explained. Temperature-voltage conversion times FR1!
1 detects the pipe temperature of the outdoor unit and converts it into voltage. ;
The output voltage of the quality voltage conversion circuit 1 is applied to the defrost start thermostat 2 and the defrost end thermostat 3, and when this voltage reaches the voltage corresponding to the defrost start temperature, the defrost start thermostat 2 (defrost holding memory 4, the output of the defrosting 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 ends, the defrost end thermometer 3 resets the defrost holding memory 4, turns the output of this defrosting holding memory 4 to "off", and at the same time Reset Stop Kuimaro. The reset forced defrost timer 6 outputs "off" for 60 minutes and prohibits defrosting.

In addition, the defrost forced termination timer 5 starts timer conversion in response to the defrost start signal, and the timer 5 starts converting the timer when the time is up (approximately 15 minutes).
Then, the defrost holding memory 4 and the forced defrost timer 6 are reset, and the defrosting is ended.

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

[Problem that the invention seeks to solve]

Since the conventional defrosting control device for the outdoor unit of the air conditioner is configured as described above, when the defrosting operation starts, 'tr5' on the high pressure side. Because the refrigerant flows rapidly into the outdoor unit piping,
As shown in Figure 4, the pipe temperature rises, but this temporary temperature rise activates the defrost end thermometer 3 and resets the defrost prohibition timer 6, so if defrosting is insufficient, Defrosting ends even though it is there.

This resulted in defrosting failure, leading to lack of heat, damage to pipes, etc., and significantly lowering the reliability of the system.

This invention was made to solve this problem, and has a simple circuit configuration that allows the piping to run for a few minutes after the start of defrosting.
To provide a defrosting control device for an air conditioner that can perform appropriate defrosting operation without terminating defrosting even if the dust level increases.

[Means for solving problems]

The defrost control device for an air conditioner according to the present invention is provided with a defrost holding timer that prevents the function of the defrost end thermostat from working after the start of defrosting operation.

[For production]

In this invention, the defrost holding timer 8 is activated by the output of the defrost forced termination timer, and the defrost termination thermometer is not operated for several minutes after the start of defrosting operation, and the rapid flow of liquid refrigerant is prevented. To prevent defrosting from being terminated even when the defrosting is insufficient.

〔Example〕

Embodiments of the defrosting 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 one embodiment of the present invention, and in FIG. 1, the parts indicated by 1 to 7 are completely the same as those in the conventional example.

In this invention, a defrost holding timer 8 is newly added to the configuration shown in FIG. The defrost holding timer 8 receives the 8-divided output of the defrost compulsory end timer 5 and stops the operation of the defrost end thermometer 3 for several minutes after the start of defrosting.

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

The specific circuit configuration of this defrosting holding timer 8 is shown in FIG. 1, and FIGS. 3(in) to 3(e) are time charts showing its operation.

In this FIG. 12, the output of the defrost forced termination timer 5 of FIG. 1 is input to the input terminal T1, and the input terminal T1 is connected to the power supply via a resistor R1. , are connected to the pace of transistor Q through resistor R2.

A resistor R3 is connected between the pace and emitter of transistor Q1.
is connected and this emitter is grounded. The collector of the transistor Q1 is connected to a power supply via a resistor R4, and is also connected via a diode DI and a resistor 9 to the (g) input terminal of a comparator 11.

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

A resistor 9 and a capacitor 10 determine the time constant of the CR timer, and a comparator 11
Detects the R timer voltage and outputs the defrost holding output to diode D.
3 to the output terminal T2.

The H input terminal of the comparator 11 is connected to the connection point between the resistors R5 and R6. This series circuit of resistors R5 and R6 is connected between the power supply and ground.

A reference voltage is applied to the input blade end of the comparator rake 11 by the resistors R5 and R6.

Next, the operation of this invention will be explained. From the moment defrosting is started, the defrosting output (defrosting signal) shown in the third doctor becomes "H", and at the same time defrosting starts as shown in FIG. (Fig. 3 fc) through resistor R4, diode D1, and resistor 9.
Charging is started with a time constant determined by the resistor 9 and capacitor 10, as shown in FIG.

In addition, the input terminal T1 of the defrost holding timer 8 receives a signal rLj, "■]" from the defrost forced termination timer 5 at a frequency divided by 8/15 (just under 2 minutes) as shown in FIG. 3(b). is input, and as a result, the charging voltage of the capacitor 10 is charged with a rest time of a little less than one minute. By dividing this voltage using predetermined resistors R5 and R6 and comparing it with the reference voltage using the comparator 11, it is possible to calculate the
When the charging voltage of the capacitor 10 becomes higher than the reference voltage (dl), the output voltage of the comparator 11 is passed through the diode D3 to the output terminal T2 as the output of the defrost holding timer 8, as shown in FIG. to rHJ, reset the defrosting end thermostat 3 and return to normal operation.

Furthermore, upon completion of defrosting, the output of the defrosting memory 4 is applied to the terminal T3 of the defrosting holding timer 8.
(The capacitor 10 is set and discharged.

By configuring the circuit as shown in Figure 3 (e)
), the defrost end thermometer 3 is set to 2 to 3 after the start of defrosting.
Since it does not operate for 3 minutes, defrosting may not end due to a temporary rise in piping temperature due to the sudden flow of liquid refrigerant (hot gas) into the outdoor unit piping at the beginning of defrosting (if there is sufficient defrosting time). is ensured, and defrosting failures do not occur.

In addition, in the above embodiment, the defrosting holding timer is configured by the CR timer, but other timers, ICs, etc. may be used.

Further, in the above embodiment, a defrosting control device for an outdoor unit that is used during heating of an air conditioner has been described, but it is also effective for defrosting a low-pressure refrigerant circuit of a hot water source such as a chilling unit.

〔Effect of the invention〕

As explained above, this invention is equipped with a defrost retention timer that maintains the defrost state even if the pipe temperature reaches the predetermined return temperature for several minutes after the start of defrosting operation, making it easy to configure the conventional equipment. By adding a defrost holding timer, sufficient defrosting can be performed, and it is possible to prevent overheating, high pressure cuts, and piping damage due to insufficient defrosting, resulting in a highly reliable system. .

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the defrosting control device for an air conditioner according to Makoto's invention, Fig. 2 is a circuit diagram showing the specific circuit configuration of the defrost holding timer, and Fig. A time chart to explain the operation of the frost retention timer, Figure 4 shows the timing during defrosting! v! 5 is a block diagram of a conventional defrosting control device for an outdoor unit of an air conditioner. 1. Temperature-voltage converter, 2. Defrost start thermostat, 3. Defrost end thermostat, 4. Defrost retention memory, 5. Defrost forced end timer, 6. Defrost prohibition timer, 7. Contact drive. Circuit, 8: Defrost holding timer, 9: Resistor, 10: Capacitor, 11' Comparator@In addition, the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (4)

[Claims] (1) When the piping temperature of the refrigerant circuit of the air conditioner reaches the defrost start temperature, the output from the defrost start thermostat is held, and when the piping temperature reaches the defrost end temperature, the defrost is reset by the defrost end thermostat. Holding memory, defrost prohibition timer that is reset at the end of defrosting by the defrosting holding memory and prohibits defrosting operation for a predetermined period of time after the end of defrosting and when the power is turned on; A forced defrost termination timer resets the defrost retention memory and the defrost prohibition timer.The output of this forced defrost termination timer causes the operation of the defrost termination thermometer to be stopped for a predetermined period of time, and upon termination of defrost, the defrost retention memory is reset. A defrost control device for an air conditioner comprising a defrost holding timer that is reset by output. (2) The defrost holding timer is a C.
The defrosting control device for an air conditioner according to claim 1, characterized in that it is configured with an R timer. (3) The defrosting control device for an air conditioner according to claim 1, wherein defrosting is performed on the outdoor unit during heating of the air conditioner. (4) The defrosting control device for an air conditioner according to claim 1, wherein defrosting is performed on a low-pressure refrigerant circuit of a hot water source.