JPS6346346A - Refrigerator - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a refrigeration system in which measures are taken to prevent refrigerant starvation operation. The cold air that connects the discharge port and the suction port! From the upstream side to the downstream side of the t1fI ring piping, a condenser for liquefying high-temperature, high-pressure gas-phase refrigerant, a pressure reducing device, and an evaporator for absorbing heat are interposed in order from the upstream side to the downstream side, and in the part where the refrigerant flows as a gas, the piping There is a high possibility that refrigerant may leak from parts such as joints and valve mechanisms. Since the circulating oil for the compressor is mixed in the refrigerant and circulated together, there is a risk of seizing as the amount of lubricating oil accumulated in the compressor 1 decreases if operation with insufficient refrigerant continues. will also arise.

As a countermeasure, a method has been adopted in which a low-pressure cut pressure switch is provided in the high-pressure refrigerant flow path upstream of the pressure reducing device, and the operation of the compressor is stopped when the refrigerant pressure falls below a set level.

However, this low pressure cut pressure switch is not sensitive enough, and even if there is no shortage of refrigerant, malfunctions may occur when the compressor is rotating at low speed or at low temperatures. ``Japanese Patent Application Laid-Open No. 58-95175J focuses on the fact that the refrigerant temperature is dependent on the refrigerant temperature during operation with insufficient refrigerant. A method for stopping the process is disclosed.

[Problems to be Solved by the Invention] The set operating pressure of the above-mentioned low pressure cut pressure switch must be higher than the saturation pressure of the refrigerant at the lowest temperature in the place where the refrigeration equipment is used. , the value was so low that refrigerant shortage could only be detected when the compressor was stopped. While the compressor is in operation, the high-pressure refrigerant flow path provided with this switch is maintained at a pressure level much higher than the above-mentioned set operating pressure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a refrigeration system that can detect a refrigerant shortage state with sufficiently high operational reliability and ensure safe operation even when the refrigeration system is inactive as well as during operation.

[Means for solving the problems] In order to achieve the above object, the refrigeration apparatus according to the present invention has the following features:
In a refrigeration system in which a compressor, a condenser, a pressure reducing device, and an evaporator are interposed in refrigerant circulation piping, the refrigerant is provided near a discharge port of the compressor and detects refrigerant temperature or refrigerant pressure. a detection means; a first actuation means for operating the drive intermittent means to a stop side when the detection means detects a cold tsN temperature higher than a set level or a refrigerant pressure lower than a set level; A refrigerant bypass passage for connecting both the refrigerant flow passages on the low pressure side and the refrigerant flow passage, a valve means interposed in the refrigerant bypass passage, and a refrigerant pressure above a set level or a refrigerant pressure below the set level. a refrigerant flow control means for opening the valve means when the refrigerant pressure is detected, and a refrigerant flow control means provided in the high-pressure side refrigerant flow path, which operates the drive intermittent means to the stop side when the refrigerant pressure falls below a set level. A configuration including a second actuating means for the operation is adopted.

[Operation and Effects of the Invention] If the refrigeration system is operated with insufficient refrigerant filled in the refrigeration recycle or after a temporary overload condition,
The temperature of the refrigerant discharged from the compressor increases. When the detection means detects the discharge refrigerant temperature higher than the set level or the refrigerant pressure lower than the set level, the drive intermittent means stops the rotation of the compressor, and at the same time the valve means opens to detect the high pressure and the low pressure side. The two refrigerant flow paths are directly connected via the refrigerant bypass path 3 without going through a pressure reducing device, and the refrigerant pressure in both flow paths is almost instantly equalized to the amount of refrigerant in the 1° refrigeration cycle. The second operating means (pressure switch for low pressure cut) for stopping the compressor when a shortage occurs is interposed in the high pressure side refrigerant flow path, so it is not possible to use the conventional device without the refrigerant bypass path 3. Even in a refrigerant shortage state, the refrigerant pressure in the high-pressure side refrigerant flow path is maintained at a high level while the apparatus is in operation, so the second actuating means cannot perform its role.

Furthermore, if the device of the present invention is not provided with a refrigerant bypass path, the above-mentioned cold t! ! When the equipment is stopped due to overheating or a drop in refrigerant pressure, the refrigerant pressure in the high and low refrigerant flow paths is gradually equalized through the pressure reducing device as a resistor in the flow path. 2. Even if the pressure is reduced to a level that allows the operating means to function, it will take a considerable amount of time, and during this time the refrigerant, once heated to a high temperature, gradually cools down to 7.
It is quite possible that the operation of the equipment will be restarted. In this case, it becomes impossible to detect a refrigerant shortage condition (S) and interrupt operation to protect the safety of the device.

However, in the device of the present invention, as mentioned above, as soon as the operation of the device is stopped due to a drop in the refrigerant temperature or a 1.5-degree drop in the refrigerant pressure, the high and low refrigerant channels are brought into conduction and the refrigerant is equalized. So,
Before restarting operation as the gastric temperature refrigerant is allowed to cool, the depressurizing means is brought into a state where it can operate normally, thereby achieving the object of the present invention.

[Example] The configuration of the present invention will be specifically described below based on an example shown in the drawings.

FIG. 1 is a refrigeration cycle diagram when the present invention is applied to a refrigeration system for a refrigerated vehicle. Magnetic clutch 1 as a drive disconnection means from a vehicle running engine (not shown)
The compressor 11 to which rotational force is transmitted through the refrigerant circulation pipe a1 connects its discharge port 11a and suction port 11b.
and a2 are connected.

In the refrigerant circulation pipes a1 and a2, condensers 1 for cooling and liquefying the compressed gas-phase chilled tofu at high temperature and high pressure are sequentially installed from the upstream side.
2, a receiver 13 as a temporary storage tank for liquid refrigerant, a dryer 19 for drying the refrigerant, a pressure reducing device 14 such as a temperature-operated expansion valve, and a cold I! An evaporator 15 is interposed as a heat exchanger for 1i1 generation.

Out of the total length of the refrigerant circulation piping, the discharge port 11 of the compression type 11
A to the pressure reducing device 14 is a high-pressure side refrigerant flow path a1 in which a relatively high-pressure refrigerant flows, and from the pressure reducing device 14 to the compressed (Iku 11) suction port 11b, a relatively low-pressure refrigerant flows. It forms a low-pressure side cold tofu flow path a2 through which the refrigerant flows.

The high-pressure side refrigerant flow path a1 is provided with a temperature switch 1 placed close to the compressor discharge port 11a on the most upstream side and serving as a detection means, a first actuation means, and a refrigerant flow control means. be. This switch 1 is a normally closed type that is turned off electrically when the refrigerant temperature exceeds a set level, for example 140°C.

Further, a low pressure cut pressure switch 2 as a second operating means is connected between the receiver 13 and the pressure reducing device 14 of the refrigerant flow path a1. This switch 2 is a normally closed type in which an electrical contact is turned off when the refrigerant pressure drops below a set level, for example, 2.1 kg/cd-G. Note that the refrigerant flow path 01 is also provided with a high pressure cut pressure switch 18 for stopping the operation of the apparatus and preventing damage to equipment when the refrigerant pressure rises above a set level.

In the boundary area between the high pressure side and low pressure side cold tofu flow paths a1 and 82,
Pressure reducing device 14 and low pressure cut pressure switch 2
A refrigerant bypass path 3 is connected to connect the two refrigerant flow paths a1 and a2 by bypassing the refrigerant flow paths a1 and a2, and a bypass path valve (electromagnetic valve) 4 as a valve means for opening and closing the flow path is connected to the bypass path 3. is interposed. The valve 4 is a normally closed type that opens when electricity is applied.

The evaporator 12 is cooled by a fan driven by a blower motor 16, and the evaporator 15 is provided with a blower motor 11.
A fan driven by blows air for the cold section inside the freezer (storehouse).

FIG. 2 shows an example of an electric circuit for operating the cold 7iJ device shown in FIG. 1. 20 is a humidity control amplifier for keeping the inside of the freezer (storehouse) at a desired temperature; 21 is an electricity for a compression relay for turning on/off the energization of the solenoid coil 25 of the magnetic clutch 10 for intermittent operation of the compression mode 11; 21a is the excitation coil of the relay (numerals with a lowercase letter a in the figure represent the excitation coil of the relay with the corresponding number) u22 is the temperature switch 1 A refrigerant temperature relay 23 is a bypass valve relay that controls the energization of the solenoid coil 27 for opening and closing the bypass valve 4, and 24 is a temperature measuring thermistor 26 in the freezer that turns on and off. It is a thermorelay that moves.

30 is a defrost control amplifier for the freezer, 31 is a refrigeration switch that controls the use of the freezer, 32 is a defrost switch, 3
3 is a defrosting relay, 34 is a defrosting nermostat, and 35 is a defrosting lamp.

41 and 42 are two blower motors 16A for the condenser 12
and 163, respectively, a relay for turning on and off electricity, 43
are two blower motors 17AJ3 and 17B for the evaporator.
50 is an alarm control amplifier that notifies abnormal operation of the refrigeration equipment, 51 is an alarm relay, 60 is an engine gear switch, 61 is a main relay for starting the equipment, and 70 is an on-board battery. It is a power source.

Next, we will divide the operation of the above-mentioned example device into three states: normal operation with an appropriate amount of refrigerant, suspension of operation due to insufficient amount of refrigerant, and when insufficient amount of refrigerant occurs during operation. explain.

[During normal operation] The normally closed temperature switch 1 for detecting refrigerant discharge temperature and the pressure switch 2 for low pressure cut are kept in the off state,
The pressure switch 18 for the high-pressure cammill is also in the on state.

After starting the engine with the engine key switch 60, the main relay 61 is also turned on by turning on the refrigeration switch 31 for operating the refrigeration system, and the alarm relay 51 is conducted to the contact side (on side). When the temperature inside the freezer detected by the thermistor 26 is higher than the set level, the compressor relay 21 and the blower motor relay 4 are activated.
1 to 43 are all turned on, the compressor 11 and motors 16 and 17 are driven, and the refrigeration system is operated in a normal state, and the refrigeration lamp 37 is turned on. At this time, temperature switch 1 is in the on state, so refrigerant temperature relay 2
2 is in the OFF position, and accordingly, the bypass valve relay 23 is also kept in the OFF state, and the bypass valve 4 is closed.

The flow of refrigerant during this operation is such that the gas phase refrigerant is compressed to high temperature and high pressure by the compressor 1j111, first flows into the condenser 12, is cooled and liquefied by the movement of the fan driven by the fan 16, and is then transferred to the receiver. A mouthful can be saved within 13 days. The liquid refrigerant sent out from the receiver 13 and dried by the dryer 19 is reduced in pressure to a gas/liquid two-phase state by passing through the pressure reducing device 14, and is driven by the blower Tanabata 17 while passing through the evaporator 15. The latent heat of vaporization is removed from the circulating air in the freezer, which is blown onto the evaporator by a fan, and the air performs the refrigeration work.The air then returns to the gas phase and is sucked into the compressor 11 to repeat the refrigeration cycle. .

[When the operation is stopped under a refrigerant shortage condition] The compressor 11 is stopped and the high pressure side and low pressure stationary refrigerant flow path a
Under the condition that the refrigerant pressure in 1 and a2 is equalized,
When the pressure drops below the set operating pressure of the +It pressure cut pressure switch 2, that is, when a refrigerant shortage condition is detected, the switch 2 is turned off, and the contact of the alarm relay 51 is turned off to the C side (off side). Therefore, the alarm control [1
- The refrigeration lamp 37 blinks when the power is applied to the engine 50, and the compressor relay 21 and the engine 1 motor 41 to
43 is turned off, so even if the refrigeration switch 31 is turned on to operate the freezer, the device will not start up, thereby preventing the start of operation with insufficient refrigerant.

At this time, the temperature switch 1 is kept on, so the bypass valve 4 remains closed.

[When a refrigerant shortage occurs during operation] When the refrigerant shortage occurs due to refrigerant gas leakage from the refrigerant piping system, the temperature inside the freezer discharged from the compressor 11 begins to rise. However, as mentioned above, temperature fluctuations in cold rIX also occur during temporary overload operation of the device1! ? Ru. When this temperature exceeds the set operating level of the temperature switch 1, for example 140° C., the switch 1 is turned off and the contact of the alarm relay 51 is also switched to the off side. Accordingly, the equipment can be operated automatically in the same way as when the operation is stopped as described above. It will be turned off.

On the other hand, when the temperature switch 1 is turned off, the cold tIX temperature relay 22 is turned on as described above, and the bypass valve relay 23 is also turned on, so that the solenoid coil 27 for opening the bypass valve 4 is energized. The refrigerant bypass path 3 is then opened. That is, at the same time as the temperature switch 1 is turned off, both the high-pressure side and low-pressure side refrigerant flow paths a1 and a2 are brought into conduction and the pressure is equalized. This means that the device of the present invention, unlike the conventional device, can perform the function of the low pressure cut pressure switch 2 even during operation.

If the refrigerant bypass path 3 does not exist, the refrigerant pressure in the high B side refrigerant flow path a1 will not be affected by the compression (as described above) even if the refrigerant shortage operation occurs during the operation. Setting f of pressure switch 2 for low pressure cut
It is unlikely that the dynamic pressure will drop below l dynamic pressure.

If the cause of the rise in refrigerant temperature is primarily due to temporarily overloaded operation of the device, the temperature switch 1 will be turned on again once the overload condition is resolved, but the pressure switch for low pressure cut has already been turned on. Since temperature switch 2 actually detects a lack of refrigerant and is activated, even if temperature switch 1 is turned on again, the operation of the device will not be restarted.

By the way, as mentioned in the technique of JP-A-58-95175J, the refrigerant temperature simply exceeds the set level and the refrigerant pressure
According to the method of determining refrigerant shortage when detecting that rU has fallen below a certain level, when attempting to detect refrigerant shortage while the RVlj is operating, the low pressure cut switch must be activated as described above. Since it is necessary to equalize the pressure between the high and low refrigerant flow paths, for example, first, the upper limit of the refrigerant temperature is detected and the operation of the equipment is stopped, so that the pressure between the two refrigerant tR flow paths is naturally equalized. Even if the low-pressure cut switch is activated with a low-pressure cut switch, it will take at least several minutes to reach this equal pressure state, so the refrigerant temperature will drop during this time, and even if there is actually a refrigerant shortage, the above The shortage determination condition is not satisfied forever, and therefore, it is impossible to detect refrigerant shortage while the device continues to operate.

FIG. 3 shows an operation flowchart of the apparatus of the above embodiment. Cold g
When the temperature rises above a set level, the temperature switch 1 is turned off, stopping the operation of the device and opening the bypass valve 4.

Accordingly, the high and low refrigerant flow paths are immediately connected to equalize the pressure, and the low pressure cut pressure switch 2 is brought into a normal four-motion state. If the refrigerant pressure is below the set level, switch 2 is turned off, so the equipment continues to be out of operation, and damage to the equipment due to insufficient refrigerant amount is prevented.If the refrigerant pressure is above the set level, Since the amount of refrigerant is not insufficient 1), the operation of the device is resumed as the temporary overload operating condition is resolved and the refrigerant temperature decreases.

The elements constituting the device of the present invention are not limited to those shown in the above embodiments, and may be replaced with various other substitutes having the same movement.

For example, when the compressor 11 is driven by an electric motor, an electric switch may be used instead of the magnetic clutch 10. In addition, when there is a refrigerant shortage, the temperature of the refrigerant discharged from the compressor 1111 increases and the refrigerant pressure on the discharge side of the pressure IIa machine 11 decreases considerably, so it is detected that this refrigerant pressure has decreased to a set level, for example, 10 kg/ci・G or less. A pressure switch (sensor) can also be used in place of the temperature switch (sensor) 1 described above.

Further, the cryogenic liquid constituting the apparatus of the present invention is not limited to the one shown in FIG. 1, and can be configured in various circuit configurations.

[Brief explanation of drawings]

1 to 3 each illustrate an embodiment of the device 5 according to the present invention, in which FIG. 1 is a refrigeration cycle diagram, FIG. 2 is an electrical circuit diagram for operating the device, and FIG. This is an operational chart of the device. In the figure: 1... Detection means (temperature switch serving as first actuation means and refrigerant flow control means) 2... Second actuation means (pressure switch for low pressure cut) 3... Refrigerant bypass path 4... Valve Means (bypass valve) 10...
- Drive intermittent means 11... Compressor 12... Condenser 14... Pressure reducing device 15... Evaporator 11a...
Discharge port 11b...Suction port al and al...High pressure side and low pressure side cold W, flow path Fig. 3

Claims (1)

[Claims] 1) A compressor, a condenser, and a pressure reducing device equipped with drive intermittent means;
and a refrigeration system in which an evaporator is interposed in a refrigerant circulation pipe, the detection means being provided near the discharge port of the compressor and detecting refrigerant temperature or refrigerant pressure, and the refrigerant temperature being higher than a set level. or a first actuating means for operating the drive intermittent means to a stop side when a refrigerant pressure lower than a set level is detected; and a refrigerant for bypassing the pressure reducing device and making both the high-pressure side and low-pressure side refrigerant flow paths conductive. a bypass passage, a valve means interposed in the refrigerant bypass passage, and a refrigerant flow control for opening the valve means when the detection means detects a refrigerant temperature above a set level or a refrigerant pressure below a set level. and a second actuation means provided in the high-pressure side refrigerant flow path for causing the drive intermittent means to stop when the refrigerant pressure drops below a set level.