JPH11211243A - Cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent refrigerant from being condensed through a precooler by arranging a bypass piping through a three-way valve between the inlet side and the outlet side of the precooler and controlling the precooler three-way valve depending on the outer air temperature thereby varying a refrigerant flow through the precooler. SOLUTION: A bypass piping 8 is arranged between the inlet side and the outlet side of a precooler 2 and a three-way valve 9 is disposed at the joint of the inlet of the bypass piping 8 and the precooler 2. Since refrigerant 6 is susceptible to condensation in the precooler 2 at the time of low outer air temperature, it is returned through the bypass piping 8 back to a compressor 1 thus protecting the refrigerant 6 against condensation. Since the refrigerant 6 is not condensed in the precooler 2 at the time of high outer air temperature, it is not passed through the bypass piping 8 but passed only through the precooler 2 and cooled. Since the refrigerant 6 is not condensed in the precooler 2, viscosity of lubricant in the compressor 15 prevented from lowering due to dissolution into liquid refrigerant resulting in smooth lubrication at the sliding part of the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a refrigerator, a showcase, a vending machine and the like.

[0002]

2. Description of the Related Art Conventionally, as a cooling device of this type, there is a cooling device disclosed in Japanese Patent Application Laid-Open No. 6-60262.

Hereinafter, description will be made with reference to the drawings. FIG.
In 3, 1 is a compressor, 2 is a pre-cooler, 3 is a condenser, 4 is a decompression device, and 5 is an evaporator, which is connected in order to form a cooling system. Reference numeral 6 denotes a refrigerant, which is charged into the cooling system. Reference numeral 7 denotes a lubricating oil that has a function of preventing wear of sliding parts of the compressor 1 and cooling the compressor 1.

In the above configuration, when the compressor 1 is in an operating state, the refrigerant 6 is compressed into a high-temperature high-pressure gas phase,
It is cooled by the precooler 2 and returns to the compressor 1. Then, it is sent to the condenser 3 and condensed to become a liquid-phase refrigerant. Next, the pressure is reduced by the pressure reducing device 4 and vaporized by the evaporator 5, whereby the evaporator 5 is cooled and sucked into the compressor 1 again, and this operation is repeated. At this time, in the case of a high outside air temperature or a high load condition where the cooling load is large, the temperature of the compressor 1 and the lubricating oil 7 is suppressed by lowering the temperature of the refrigerant 6 by cooling with the pre-cooler 2, and the reliability of the cooling device Performance can be improved. On the other hand, at low outside air temperature or under a low load condition where the cooling load is small, a part of the refrigerant 6 is condensed by the pre-cooler 2 and returns to the compressor 1 in a liquid phase state. Is present and dissolved in the lubricating oil 7. In addition, lubricating oil 7
Is partially discharged from the compressor 1 together with the refrigerant 6, but returns to the compressor 1 immediately after circulating through the precooler 2, so that the discharge amount of the lubricating oil 7 from the compressor 1 to the condenser 3 and the evaporator 5 Can be suppressed. Therefore, the lubricating oil returning to the compressor 1 is also good by the pre-cooler 2, and the amount of lubricating oil required by the compressor 1 can be secured, so that the reliability of the cooling device can be improved.

[0005]

However, in the above-mentioned conventional configuration, the precooler 2 works effectively at a high outside air temperature or under a high load condition with a large cooling load, but at a low outside air temperature or a small cooling load. Under low load conditions, a part of the refrigerant 6 is condensed in the pre-cooler 2 and returns to the compressor 1 in a liquid phase, so that it dissolves in the lubricating oil 7 and lowers the viscosity of the lubricating oil 7 to improve the lubricating action of the sliding portion. This may hinder the operation and adversely affect the reliability of the cooling device.

When the lubricating oil 7 having low compatibility with the refrigerant 6 is employed as the lubricating oil 7, a part of the refrigerant 6 is similarly condensed by the precooler 2 and returns to the compressor 1 in a liquid phase. The liquid refrigerant and the lubricating oil 7 are separated into two layers in the compressor 1, and the liquid refrigerant is guided from the lubricating oil supply mechanism of the compressor 1 to the sliding portion, which hinders the lubricating action and reduces the reliability of the cooling device. There is also a fear that the property is adversely affected.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a cooling device that does not condense a refrigerant with a precooler.

[0008]

According to the present invention, a bypass pipe is provided between an inlet side and an outlet side of a precooler through a three-way valve, and the capacity of the precooler is adjusted according to the outside air temperature. The three-way valve is controlled by detecting the temperature difference between the pre-cooler return portion and the condenser or the compressor temperature to change the flow of the refrigerant in the pre-cooler. In addition, only for a certain period of time from the start of the compressor, a three-way valve flows through the bypass pipe, and thereafter flows through the entire precooler.

With the three-way valve and the bypass pipe provided in the precooler, the refrigerant can be prevented from being condensed regardless of the outside air temperature condition.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a pre-cooler according to a first embodiment of the present invention; And a three-way valve connecting the precooler and an inlet of the bypass pipe. In such a cooling system, the three-way valve of the precooler is caused to function according to the outside air temperature condition, and a part of the refrigerant is caused to flow through the bypass pipe to change the capacity of the precooler, thereby preventing the refrigerant from condensing.

According to a second aspect of the present invention, there is provided the cooling system according to the first aspect, wherein a temperature detecting means is provided in the return portion of the precooler and the condenser, and the arithmetic portion for comparing respective temperatures is provided, It has a three-way valve control part that controls the valve, so by controlling the three-way valve and opening and closing the bypass pipe by the temperature difference between the pre-cooler return part and the condenser, the amount of refrigerant to the pre-cooler is changed and condensation is prevented. can do.

According to a third aspect of the present invention, in the cooling system according to the first aspect, a compressor temperature detecting means is provided in the compressor, a computing unit for comparing temperatures, and a three-way valve for controlling the three-way valve. Since it has a valve control unit,
When the compressor temperature is low, the bypass pipe is opened to prevent the refrigerant from condensing in the pre-cooler, and when the compressor temperature is high, the bypass pipe is closed and the temperature can be reduced through the pre-cooler.

According to a fourth aspect of the present invention, in the cooling system according to the first aspect, a compressor is provided with a compressor operation detecting means, and a timer for counting time since the start of the compressor; Since the arithmetic unit that compares the time of the timer and the three-way valve control unit that controls the three-way valve are provided, the bypass pipe is opened with the three-way valve for a certain time after the compressor is started, and the refrigerant in the precooler is used. The three-way valve is closed when the refrigerant temperature and the compressor temperature rise after a certain period of time, and the refrigerant can be passed through the precooler to lower the temperature.

As described above, in any case, by controlling the condensation of the refrigerant, wear of the sliding portion of the compressor can be prevented, and the reliability of the cooling device can be improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those in the related art are denoted by the same reference numerals, and detailed description is omitted.

(Embodiment 1) In FIG. 1, 1 is a compressor,
Reference numeral 2 denotes a precooler, which is formed in a coil shape to secure a heat radiation area, and a pipe, a finned copper pipe, or the like is applied. Reference numeral 3 denotes a condenser, in which a part of the precooler 2 is provided. Reference numeral 4 denotes a decompression device, for example, a capillary tube or an expansion valve is used. 5 is an evaporator, 6 is a refrigerant, and 7 is a lubricating oil. Reference numeral 8 denotes a bypass pipe provided between the inlet side and the outlet side of the precooler 2. 9 is the bypass pipe 8
The refrigerant 6 can flow in either the a direction or the b direction by switching the valve with a three-way valve provided at the connection between the pre-cooler 2 and the inlet of the pre-cooler 2. The direction a indicates the direction of the precooler 2, and the direction b indicates the direction of the bypass pipe 8.

In FIG. 2, reference numeral 10 denotes an outside air temperature detecting means using a thermistor or the like, which is mounted at a place where the outside air temperature can be detected. Reference numeral 11 denotes a calculation unit, and reference numeral 12 denotes a three-way valve control unit using a relay or the like.

In the above configuration, as shown in FIG.
In STEP1, the outside air temperature detecting means 10 detects the outside air temperature T.
Detect _A.

In STEP 2, the arithmetic unit 11 sets the outside air temperature T_A
And the preset temperature T₁Perform a comparison operation with. An example
For example, T₁Is 15 ° C and the outside air temperature T_AIs 5 ° C, T_A
<T ₁Holds, and T₁Is 15 ° C and the outside air temperature T_AIs 30
For ° C, T_A<T₁Does not hold.

In STEP 3, when T _A <T ₁ is satisfied in the calculation unit 11, the three-way valve control unit 12 opens the direction b of the three-way valve 9 and closes the direction a. Therefore, the refrigerant 6 flows through the bypass pipe 8 and the cooling effect of the pre-cooler 2 is reduced, so that condensation of the refrigerant 6 can be prevented. Conversely, if T _A <T ₁ does not hold, the three-way valve controller 12 opens the three-way valve 9 in the direction a and closes the direction b. Therefore, although the refrigerant 6 is cooled only through the precooler 2, the condensation of the refrigerant 6 can be prevented when the outside air temperature is high.

As described above, when the outside air temperature is low, the pre-cooler 2
When the refrigerant 6 is easily condensed, the refrigerant 6 can be returned to the compressor 1 via the bypass pipe 8 to prevent the refrigerant 6 from being condensed. Conversely, when the refrigerant 6 does not condense in the precooler 2 at a high outside air temperature, the refrigerant 6 can be cooled only by passing through the precooler 2 without passing through the bypass pipe 8. Therefore, there is no condensation of the refrigerant 6 in the precooler 2 and the compressor 1
To prevent the viscosity of the lubricating oil 7 from decreasing due to the incorporation of the liquid refrigerant into the lubricating oil 7 inside the lubricating oil 7, smoothen the lubricating action of the sliding part of the compressor 1, improve the wear resistance, and improve the reliability of the cooling device. Can be.

Also, in the case of a cooling device using a lubricant having low compatibility with the refrigerant 6 as the lubricating oil 7, the construction and operation thereof are the same, and the condensation of the refrigerant 6 in the precooler 2 and the lubrication in the compressor 1 are performed. Prevents two-layer separation of oil 7 and liquid refrigerant, smoothes the lubricating action of the sliding part of compressor 1 and enhances wear resistance,
The reliability of the cooling device can be improved.

(Embodiment 2) In FIGS. 4 and 5, reference numeral 13 denotes a return portion temperature detecting means such as a thermistor, which is attached to a precooler return portion returning from the precooler 2 to the compressor 1. Reference numeral 14 denotes a condenser temperature detecting means using a thermistor or the like.
It is attached to the outlet of the condenser 3.

In the above configuration, as shown in FIG.
STEP1 detects the returning portion temperature T _B of the precooler 2 by the return portion temperature detecting means 13.

STEP 2 is the condenser temperature detecting means 1
At 4, the condenser temperature T _C is detected. STEP3 includes a temperature difference between the return portion temperature T _B in the calculating portion 11a condenser temperature T _C,
Performing a comparison operation between the temperature difference T ₂ that is set in advance. For example, in T ₂ is 10 ° C., the return portion temperature T _B is 15 ° C., a condenser temperature T if _C is 10 ° C., T _B -T _C <T ₂ is holds, T ₂ is returned at 10 ° C. portion temperature T _{When B} is 60 ° C. and the condenser temperature T _C is 45 ° C., T _B −T _C <T ₂ does not hold.

In STEP 4, the calculation unit 11a calculates T _B -T _C
When <T ₂ holds, the three-way valve 9 is opened by the three-way valve controller 12 in the direction b and closed in the direction a. Therefore, the refrigerant 6 flows through the bypass pipe 8 and the cooling effect of the pre-cooler 2 is reduced, so that condensation of the refrigerant 6 can be prevented. Conversely, T _B -T
If _{the C} <T ₂ does not hold, the three-way valve control unit 12 three-way valve 9 is opened in a direction to close the b direction. Therefore, although the refrigerant 6 is cooled through the pre-cooler 2, T _B
Coolant 6 is not condensed in precooler 2 for temperature difference -T _C is large.

As described above, when the temperature difference (T _B -T _C ) between the return portion and the condenser is small and approaches the saturation temperature, the refrigerant 6 is easily condensed in the precooler 2, so that it flows into the bypass pipe 8, This can prevent the refrigerant 6 from condensing and returning to the compressor 1. Conversely, when the temperature difference between the return portion and the condenser is large, the refrigerant 6 is considerably higher than the saturation temperature and the refrigerant 6 does not condense in the pre-cooler 2 and does not pass through the bypass pipe 8,
It can be cooled through the precooler 2. Therefore, the refrigerant 6 is not condensed in the precooler 2 and the viscosity of the lubricating oil 7 is prevented from lowering due to the dissolution of the liquid refrigerant into the lubricating oil 7 in the compressor 1. The wear resistance can be increased, and the reliability of the cooling device can be improved.

(Embodiment 3) In FIGS. 7 and 8, reference numeral 15 denotes a compressor temperature detecting means such as a thermistor, which is attached to the outer surface of the compressor 1.

In the above configuration, as shown in FIG.
In STEP 1, the compressor temperature detecting means 15 controls the compressor 1
To detect the temperature T _D.

In STEP 2, the operation section 11b performs a comparison operation between the compressor temperature T _D and a preset temperature T ₃ . For example, when T ₃ is 40 ° C. and the compressor temperature T _D is 30 ° C., T _D <T ₃ is satisfied. This state is defined as a condition in which the compressor 1 is started and the temperature is reduced in a low outside temperature condition or a middle outside temperature condition. The time until it comes up is equivalent. T ₃ 40
When the compressor temperature T _D is 50 ° C. and T _D <T ₃ does not hold.

In STEP 3, the calculation unit 11b sets T _D <T ₃
Holds, the three-way valve controller 12 sets the three-way valve 9 to b.
Open in the direction and close the direction a. Therefore, the bypass pipe 8 is opened, and all the refrigerant 6 flows into the bypass pipe 8, and the cooling effect in the precooler 2 is reduced, so that the refrigerant 6 can be prevented from being condensed in the precooler 2. Conversely, if T _D <T ₃ does not hold, the three-way valve controller 12 controls the three-way valve 9.
Is opened in the direction a, and the direction b is closed. Therefore, although the bypass pipe 8 is closed and the refrigerant 6 is cooled through the pre-cooler 2, if the temperature of the compressor 1 is high, if the pre-cooler 2
Even if a part is condensed, it is vaporized immediately after returning to the inside of the compressor 1.

[0032] As described above, since there is provided a compressor temperature detection means 15 to the compressor 1, immediately after or when starting the cooling load is small, if the compressor temperature T _D is low and the like, the refrigerant 6 precooler 2 is condensed In the easy state, all of the refrigerant 6 can be returned to the compressor 1 through the bypass pipe 8 to prevent condensation. Conversely, or when operation time is long the compressor temperature T _D of the cooling load is large or when the compressor 1 is high, in a state where the refrigerant 6 is less likely to condense in precooler 2, cooled through all the coolant 6 precooler 2, Compressor 1 and refrigerant 6
Temperature rise can be suppressed. Therefore, the refrigerant 6 does not condense in the precooler 2 and the viscosity of the lubricating oil 7 can be prevented from lowering due to the dissolution of the liquid refrigerant into the lubricating oil 7 in the compressor 1, and the wear resistance of the sliding portion of the compressor 1 can be improved. In addition, the reliability of the cooling device can be improved.

(Embodiment 4) In FIG. 10 and FIG.
Reference numeral 6 denotes a compressor operation detecting means, for example, a relay or the like is attached to a power supply circuit of the compressor 1. Reference numeral 17 denotes a timer for counting the operation time from 0 when the compressor operation detecting means 16 detects the start of the compressor 1.

In the above configuration, as shown in FIG. 12, in STEP 1, the compressor operation detecting means 16 detects whether the compressor 1 has started.

In STEP 2, when the compressor 1 is started, the timer 17 starts counting the operation time K from 0.

In STEP 3, the arithmetic unit 11c sets the timer 1
7, a comparison operation between the operating time K of the compressor 1 and a preset time A is performed. For example, when A is 120 seconds and the time K of the timer 17 is 60 seconds, K ≦ A holds,
If the time K of the timer 17 is 180 seconds, K ≦ A does not hold.

In STEP4, when K ≦ A is satisfied in the calculation unit 11c, the three-way valve control unit 12 opens the three-way valve 9 in the direction b and closes the direction a. Therefore, the bypass pipe 8
Is opened, and all the refrigerant 6 flows through the bypass pipe 8, and the cooling effect in the precooler 2 is reduced.
Can be prevented from condensing. Conversely, if K ≦ A does not hold, that is, if the time since the start of the compressor 1 exceeds A, the three-way valve control unit 12 sets the three-way valve 9 to a
Open in the direction and close the direction b. Therefore, the bypass pipe 8 is closed, and the refrigerant 6 is entirely cooled through the entire precooler 2. However, when the compressor 1 is activated for a certain period of time A
, The refrigerant 6 is not easily condensed in the precooler 2, but the temperatures of the compressor 1 and the refrigerant 6 are also increasing, so that the cooling of the refrigerant 6 in the precooler 2 is effective.

In STEP 5, the compressor operation detecting means 16 detects whether the compressor 1 has stopped. When the compressor 1 stops, the three-way valve 9 is opened in the direction b by the three-way valve controller 12 and closed in the direction a in STEP6. Thereby, the condensation of the refrigerant 6 in the precooler 2 at the time of low outside air temperature and at the time of defrost can be suppressed, and the liquid return from the precooler 2 immediately after the start of the compressor 1 can be prevented.

As described above, since the compressor operation detecting means 16 and the timer 17 are provided, the compressor 1 is started and the refrigerant 6
During the time immediately after the start-up when the temperature of the compressor 1 is low, the refrigerant 6 does not pass through the pre-cooler 2 but is entirely returned to the compressor 1 by the bypass pipe 8, so that the refrigerant 6 can be prevented from condensing in the pre-cooler 2. Conversely, after a certain period of time has elapsed since the compressor 1 started and the refrigerant 6 and the compressor 1 rise in temperature, the entire refrigerant 6 can be cooled through the pre-cooler 2 without passing through the bypass pipe 8. . Therefore, the viscosity of the lubricating oil 7 can be prevented from being reduced due to the condensation of the refrigerant 6 in the precooler 2 and the dissolution of the liquid refrigerant into the lubricating oil 7 in the compressor 1.
The wear resistance of the sliding portion can be increased, and the reliability of the cooling device can be improved.

[0040]

According to the present invention as described above,
Since a bypass pipe is provided between the inlet side and the outlet side of the precooler, and a three-way valve connecting the inlet part of the bypass pipe and the precooler is provided, the refrigerant flows through the precooler and condenses in a low outside air temperature state. When easy, the refrigerant is returned to the compressor via a bypass pipe to prevent refrigerant condensation in the pre-cooler, thereby preventing a decrease in the viscosity of the lubricating oil due to the dissolution of the liquid refrigerant into the lubricating oil in the compressor.

Also, since the return portion of the precooler and the condenser are provided with temperature detecting means, when the temperature of the return portion of the precooler is close to the saturation temperature and the refrigerant is easily condensed by the precooler, the refrigerant is passed through the bypass pipe and the precooler is passed through. Prevents the refrigerant from condensing and returning to the compressor, preventing the viscosity of the lubricating oil from decreasing due to the dissolution of the liquid refrigerant into the lubricating oil in the compressor, and ensuring reliability in multi-evaporation systems and cooling systems with large load fluctuations. Can respond.

Further, since the compressor is provided with a compressor temperature detecting means, when the cooling load is small, or when the refrigerant is likely to condense in the pre-cooler, such as when the compressor temperature is low immediately after the compressor is started, The refrigerant is prevented from condensing in the pre-cooler by passing the refrigerant through the bypass pipe, and the viscosity of the lubricating oil can be prevented from lowering due to the dissolution of the liquid refrigerant into the lubricating oil in the compressor. Furthermore, since the lubricating oil temperature can be substituted for the compressor type (reciprocating, rotary, etc.) and the dissolution characteristics of the lubricating oil and the refrigerant, it can be more reliably applied to various cooling devices.

Further, since the compressor is provided with the compressor operation detecting means, when the temperature of the refrigerant and the compressor is relatively low, the refrigerant is passed through the bypass pipe for a certain time immediately after the compressor is started, and the refrigerant is discharged by the pre-cooler. Condensation can be prevented, and the viscosity of the lubricating oil can be prevented from lowering due to the dissolution of the liquid refrigerant into the lubricating oil in the compressor without being affected by a change in the outside air temperature or a change in load.

Therefore, the above-mentioned various control means are arranged on the basis of a cooling device provided with a bypass pipe via a three-way valve in a pre-cooler. In each case, refrigerant is prevented from condensing and lubricating oil in the compressor is removed. This prevents the viscosity of the lubricating oil from decreasing due to the dissolution of the liquid refrigerant, increases the wear resistance of the sliding portion of the compressor, and improves the reliability of the cooling device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cooling system of a cooling device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of the same.

FIG. 3 is an operation flowchart of the same.

FIG. 4 is a cooling system diagram of a cooling device according to a second embodiment of the present invention.

FIG. 5 is a functional block diagram of the same.

FIG. 6 is an operation flowchart of the same.

FIG. 7 is a diagram illustrating a cooling system of a cooling device according to a third embodiment of the present invention.

FIG. 8 is a functional block diagram of the same.

FIG. 9 is an operation flowchart of the same.

FIG. 10 is a diagram illustrating a cooling system of a cooling device according to a fourth embodiment of the present invention.

FIG. 11 is a functional block diagram of the same.

FIG. 12 is an operation flowchart of the same.

FIG. 13 is a diagram of a cooling system of a conventional cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Precooler 3 Condenser 4 Decompression device 5 Evaporator 6 Refrigerant 8 Bypass piping 9 Three-way valve 11, 11a, 11b, 11c Operation part 12 Three-way valve control part 13 Return part temperature detecting means 14 Condenser temperature detecting means 15 Compression Machine temperature detecting means 16 Compressor operation detecting means 17 Timer

Continuation of the front page (72) Inventor Kenjiro Tomaru 4-2-5 Takaida Hondori, Higashiosaka City, Osaka Inside Matsushita Refrigeration Co., Ltd.

Claims (4)

[Claims] 1. A compressor, a precooler, a condenser, a decompression device, an evaporator, a bypass pipe provided between an inlet side and an outlet side of the precooler, an inlet of the bypass pipe, and the precooler. In a cooling system comprising a three-way valve for connecting a refrigerant, a cooling device having a refrigerant condensation control function. 2. The method according to claim 1, further comprising: a return section of the precooler; a temperature detecting section provided in the condenser; a calculating section for comparing respective temperatures; and a three-way valve control section for controlling the three-way valve. Cooling system. 3. The cooling device according to claim 1, wherein the compressor is provided with a compressor temperature detecting means, and further includes a calculation unit for comparing temperatures, and a three-way valve control unit for controlling the three-way valve. 4. A compressor, comprising: a compressor operation detecting means; a timer for counting time since the compressor was started; an operation unit for comparing the time of the timer; and a three-way valve for controlling the three-way valve. The cooling device according to claim 1, further comprising a valve control unit.