JPS6249159A - Control circuit for refrigerator - 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 [Field of Industrial Application] The present invention relates to a control circuit for a refrigeration device used in a freezer/refrigerator oven showcase or the like.

[Conventional technology]

As shown in FIG. 4, such a refrigeration system includes a compressor (1),
A refrigeration cycle is constructed by sequentially connecting a condenser (2), a pressure reducing device (3), an evaporator (4), and an accumulator (5). A defrosting circuit with a solenoid valve (6) provided in the middle is formed between the inflow side and the inflow side.

Conventionally, as shown in Fig. 5, the control circuit of a refrigeration system configured in this manner has a main switch (7) with a high pressure switch (8) that opens when the high pressure of the refrigerant exceeds a set value.
and the control relay (IR) of the compressor (1) are connected in series,
The contact (1a) of the control relay (IR) is connected in series to the compressor motor (10) to form a control circuit for the compressor (1), while the contact of the temperature switch that controls the end of defrosting is connected in series to the compressor motor (10). A self-holding circuit is formed by connecting the contact (12a) in parallel to a series connection circuit of the self-holding relay (12) and its self-holding relay (12R).
The concubine point (12b) is the control relay (6) of the solenoid valve (6).
R), and this series connected circuit was connected in parallel to the self-holding circuit, and also connected in series to the time limit contact (lla) of the defrosting timer (11).

In addition, the contact (6a) of the control relay (6R) of the solenoid valve (6)
) is connected in series to the electromagnetic valve coil (9) and connected in parallel to the control circuit of the compressor (1).

To perform the cooling operation in this way, turn on the main switch 2.1 (7), the control relay (IR) will be energized, and its contact (1a) will close at the pressure t? The i machine motor cio> rotates and the compressor (1) starts operating. When the compression R (1) operates, the refrigerant is supplied from here to the evaporator (4) via the condenser (2) and the pressure reducing device (3), and the heat of vaporization of the refrigerant here causes the refrigerant showcase to be heated. The inside of the refrigerator is cooled. The vaporized refrigerant is then stored in an accumulator (5
) is recovered to the compressor (1) again.

By the way, in order to prevent the cooling capacity from decreasing due to frost adhering to the evaporator (4) during the cooling operation, the defrosting operation is performed at regular intervals. This defrosting operation is performed using the defrosting timer (1
1) is activated, its time-limiting contact (lla) closes, energizing the control relay (6) of the solenoid valve (6), which closes its contact (6a), and energizing the solenoid valve coil (9), causing the solenoid to This is done by opening the valve (6), and the high-temperature, high-pressure liquid refrigerant sent out from the compressor (J, ) is directly supplied to the generator (4) via the solenoid valve (6), and the liquid refrigerant is Evaporator with heat (
4) Melt the frost that has adhered to the surface. When the frost melts and the temperature of the evaporator (4) reaches a predetermined value, the f1M degree sensor (
(not shown) detects this and the temperature switch contact (12)
As a result, the self-holding relay (12R) is energized, its contacts (12a) are closed, and its contacts (12b) are opened. When the contact (12b) opens, the energization to the control relay (6R) of the solenoid valve (6) is cut off, and when the contact (6a) opens, the energization to the solenoid valve coil (9) is cut off, and the solenoid valve ( 6) is closed, and the defrosting operation ends.

Then, the compressor (1) continues to operate as it is, supplies refrigerant to the condenser (2), and the cooling operation is restarted.

By the way, even during defrosting operation, the refrigerant gas discharged from the compressor (1) R) flows into the solenoid valve (6), and a portion of it also flows into the condenser (2). , the amount of refrigerant in the condenser (2) gradually increases.

For this reason, when the defrosting operation ends and the cooling operation starts again, the increase in the amount of refrigerant accumulated in the condenser (2) causes a new high temperature to be supplied to the lock condenser (2). The area for the high-pressure refrigerant gas to condense is reduced, the condensing capacity is reduced, and the high-pressure pressure of the refrigerant temporarily increases sharply at the start of the cooling operation, as shown in FIG.

[Problem that the invention seeks to solve]

Therefore, in the conventional method of immediately closing the solenoid valve and restarting cooling operation after defrosting, the high pressure of the refrigerant in the condenser on the high pressure side reaches the set value or higher, and the high pressure switch (
8) is often activated.

As a result, the power to the control relay (IR) of the compressor (1) is cut off, its contacts (1a) open, and the compressor motor (
10), the cooling operation was stopped due to the inconvenience.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control circuit for a refrigeration system that eliminates the disadvantages of the conventional example, suppresses the rise in high pressure after the end of defrosting operation, prevents the operation of the high pressure switch, and allows smooth start of cooling operation. It's about doing.

[Failure to solve the problem]

In order to achieve the above object, the present invention configures a refrigeration cycle by sequentially connecting a compressor, a condenser, a pressure reducing device, and an evaporator, and a refrigeration cycle is constructed between the discharge side of the compressor and the inflow side of the evaporator. In a refrigeration system that has a defrosting circuit equipped with a solenoid valve,
A delay timer is connected to a contact point of a temperature switch that turns off the solenoid valve to end defrosting, and a contact point of a control relay connected to the contact point of the delay timer is connected to a control circuit of the solenoid valve and a control circuit of the compressor. The gist of each item is as follows.

[Operation] According to the present invention, when defrosting is completed and the contact of the temperature switch is closed, the delay timer is energized, and among the contacts of the relay controlled by the contact, the contact of the relay provided in the control circuit of the solenoid valve is The solenoid valve is closed, and at the same time, the circuit provided in the compressor control circuit is opened, so after the defrosting operation is completed, the compressor is stopped while the solenoid valve remains open for a certain period of time. During this time, the refrigerant accumulated in the condenser passes through the solenoid valve and moves to the evaporator.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an electric circuit diagram showing an embodiment of a control circuit for a refrigeration system according to the present invention. In the figure, the same components as those in the conventional example shown in FIG. Detailed explanation has been omitted.

The control circuit for the compression i(1) is composed of a main switch (7), a high pressure switch (8), and a control relay (IR), and the defrost circuit that controls the opening and closing of the solenoid valve (6) is composed of a defrost timer ( 11), its time-limiting contacts (11a temperature switch contact (12), its self-holding relay (12R), its contacts (12a) (12b) and solenoid valve coil 9)
and a control relay (6R) for the solenoid valve (6), which is similar to the conventional example.

In the present invention, in addition to such a configuration, a delay timer (13) is connected in series to the contact (12) of the temperature switch, and a time limit contact (13a) of the delay timer (13) is connected in series to the control relay (14). Connect this control relay (14) a
The contact (14a) is connected in parallel to the contact (6a) of the control relay (6R) that controls the solenoid valve coil (9), and the b contact (14b) is connected to the control relay (IR) of the compressor (1).
) connected in series.

Thus, the a contact (14a) and the b contact (14b) of the relay (14) controlled by the delay timer (13) in the control circuit of the solenoid valve (6) and the control circuit of the compressor (1).
are incorporated respectively.

・Next, to explain the operation, the cooling operation is the same as before, when the main switch (7) is turned on, the control relay (IR) is energized, its contact (1a)% is closed, and the compressor motor (10) is turned on. rotates, the compressor (1) starts operating, and refrigerant is supplied from here to the evaporator (4) via the condenser (2) and pressure reducing device (3), where the cooling action is performed. Cools the inside of the refrigerated freezer showcase.

After cooling operation for a certain period of time, defrosting operation starts, but as in the conventional case, the time-limiting contact (lla) closes due to the action of the defrosting timer (11) and the control relay (6) of the solenoid valve (6).
R) is energized, its contact (6a) closes, and the solenoid valve coil (9) is energized to open the solenoid valve (6). The liquid refrigerant is directly supplied to the evaporator (4) through the solenoid valve (6), and the heat of the liquid refrigerant is used to remove frost adhering to the evaporator (4).

As the defrosting operation progresses and the surface temperature of the evaporator (4) rises and reaches the set value, the contact (12) of the temperature switch closes, the self-holding relay (12R) is energized, and the contact (
12a) is closed and contact (12b) is opened, so that the solenoid valve (
The power supply to the control relay (6R) of 6) is cut off, and its contact (6a) is opened.

However, when the contact (12) of the temperature switch closes at this time, the delay timer (13) is energized at the same time, and its contact (13a) is closed.As a result, the control relay (14) is energized and its a contact (14a) closes, so the solenoid valve (
Even if the contact point (6) of the control relay (6R) (6) opens, the power to the solenoid valve coil (9) will not be cut off.

Furthermore, at the same time, when the control relay (14) is energized, its b contact (14b) opens, so the energization to the control relay (IR) of the compressor (1) is cut off, and its contact (1a) opens, causing the compressor to Since the power supply to the motor (10) is stopped, the operation of the compressor (1) is stopped.

In this way, as shown in FIG. 3, even if the defrosting operation ends when the temperature switch (ζJ) is reached, the solenoid valve (6) continues to remain open for a certain period of time due to the delay timer (13). At the same time, the operation of the compressor (1) is temporarily stopped during this time.

During this time, the refrigerant accumulated in the condenser (2) on the high pressure side during defrosting operation moves to the evaporator (4) on the low pressure side due to the pressure difference, and the amount of refrigerant in the condenser (2) decreases. However, as shown in FIG. 3, the high pressure that rose at the end of the defrosting operation decreases, and the low pressure increases, reducing the pressure difference between the two.

a) When the time set in the delay timer (13) has elapsed, the contact (13a) opens and the solenoid valve (
At the same time as 6) closes, the compressor motor (10) is energized and cooling operation starts again, but at this point the high pressure has decreased, so the high pressure switch, yf-(8)
There is no such thing as opening and compression 1a(1) stopping.

〔Effect of the invention〕

As described above, the control circuit of the refrigeration system of the present invention does not open the solenoid valve in the defrosting circuit even after the operation is finished.
By leaving it in the same state and temporarily stopping the C compressor, it is possible to prevent a sudden increase in high pressure when the cooling operation starts after the defrosting operation is completed, and as a result, the cooling operation can be resumed smoothly. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a control circuit for a refrigeration system according to the present invention, FIG. 2 is an operational time chart of this embodiment, and FIG. 3 is a characteristic curve diagram of refrigerant pressure. FIG. 4 is an explanatory diagram showing a refrigeration cycle of the refrigeration system, FIG. 5 is an electric circuit diagram showing a conventional example, FIG. 6 is an operation time chart of the same, and FIG. 7 is a characteristic curve diagram of refrigerant pressure. (1)...Compressor (IR)...Control relay (
1a)...Contact (2)...Condenser (3)...
Pressure reducing device (4)... Stalk generator (5)... Accumulator (6)... Solenoid valve (6f stone... Control relay (
6a)...Contact (7)...Main switch 71'-(8
)...High pressure Kasuinochi (9)...Solenoid valve coil (10)...Compression 1jjε
-ter (11)...Defrost timer (lla)...Defrost timer time limit contact (12)
...Temperature switch contact (12R)...Self-holding relay (12a) (12b) -Contact (13)...Delay timer (13a)...Delay timer time limit contact (14)...
・Control relay (14a) (14b)...Contact point agent of control relay Masuo Oone, patent attorney Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A refrigeration cycle is constructed by sequentially connecting a compressor, a condenser, a pressure reducing device, and an evaporator, and a defrosting circuit is formed in which a solenoid valve is provided midway between the discharge side of the compressor and the inflow side of the evaporator. In the refrigeration system, a delay timer is connected to the contacts of a temperature switch that turns off the solenoid valve and ends defrosting, and the contacts of the control relay connected to the contacts of the delay timer are connected to the control circuit of the solenoid valve and the compressor. A control circuit for a refrigeration system, characterized in that the control circuit is provided in each of the control circuits.