JP4333586B2 - Refrigeration cycle apparatus and control method thereof - Google Patents

Description

  The present invention has two evaporators in a cycle, for example, allows two refrigeration units provided in a refrigeration vehicle to be refrigerated at different temperatures and has a defrosting control function using hot gas. The present invention relates to an apparatus and a control method thereof.

  As a conventional refrigeration cycle apparatus, for example, as shown in Patent Document 1, two evaporators arranged in parallel in a refrigeration cycle are arranged in two freezers provided in a refrigeration vehicle, respectively, and have different temperature conditions. It is known that exhibits a freezing function.

  Further, as a defrosting control of the evaporator during the operation of the refrigeration cycle, for example, as shown in Patent Document 2, the condenser in the refrigeration cycle is bypassed and the high-temperature refrigerant gas (hot gas) from the compressor is evaporated. What performs defrosting by sending to is known.

Therefore, even in the case of having two evaporators, defrosting control can be performed by providing hot gas bypass passages connected to the respective evaporators.
JP 2004-132635 A Japanese Unexamined Patent Publication No. 2000-74546

  However, in the refrigeration cycle apparatus having the two evaporators and the hot gas bypass flow path, defrosting is necessary when the refrigeration function is exhibited only by the evaporator on one side, and it is connected to the evaporator. When defrosting operation is performed by flowing hot gas through the hot gas bypass channel on the other side, part of the hot gas that flows out from the evaporator on one side and returns to the compressor is discharged from the outlet side of the other evaporator There was a problem of inflowing from. This is because the refrigerant pressure in the evaporator on one side is higher than the refrigerant pressure in the evaporator on the other side maintained at room temperature because it is not used. Therefore, if this defrosting operation time continues for a long time, the lubricating oil (for the compressor) contained in the refrigerant stagnates in the other evaporator, and the lubricating oil to the compressor becomes insufficient. In the worst case, the compressor may be locked due to running out of lubricating oil.

  In view of the above problems, an object of the present invention is to have two evaporators in a cycle and enable defrosting with hot gas. In the defrosting operation of one evaporator, the lubricating oil in the refrigerant is the other. It is an object of the present invention to provide a refrigeration cycle apparatus and a control method thereof that can easily prevent stagnation in the evaporator.

  In order to achieve the above object, the present invention employs the following technical means.

In the invention according to claim 1,
Compressor (111), a condenser (112), condenser (112) first for the passage opening which is arranged in parallel between the suction side of the outlet side and the compressor (111) of the second refrigeration Open / close means (118a, 118b), first and second decompression means (114a, 114b), and first and second evaporators (115a, 115b), and the refrigerant is circulated by the compressor (111). To the refrigeration cycle (110)
By bypassing the condenser (112) from the compressor (111), the first and second hot gas bypass passages (121) connected to the inflow sides of the first and second evaporators (115a, 115b), respectively. 122)
First and second opening / closing means (131, 132) for opening and closing the first and second hot gas bypass flow paths (121, 122), respectively;
When the operation control of the refrigeration cycle (110) and defrosting in the first and second evaporators (115a, 115b) are necessary, the first and second hot gas bypass flow paths (121, 122) side In the refrigeration cycle apparatus provided with a control unit (140) for performing opening / closing control of the first and second opening / closing means (131, 132) in order to form the refrigerant flow of
The control unit (140) closes both the first and second opening / closing means (131, 132), and one of the first and second refrigeration opening / closing means (118a, 118b). open 118a), first to close the other frozen for opening and closing means (118b), a second evaporator (115a, 115b) of, whereas alone exert a refrigeration function only on a side evaporator (115a) frozen When the operation is performed, when the defrosting operation is performed because defrosting in the evaporator (115a) on one side is necessary, both the first and second refrigerating opening / closing means (118a, 118b) are closed. At the same time, the first and second opening / closing means (131, 132) are both opened, and the evaporation on the one side that exhibited the refrigeration function from the first and second hot gas bypass channels (121, 122) is performed. In addition to the vessel (115a) Volatilization and were not the other side evaporator (115b) is also characterized by supplying the refrigerant.

  Thereby, in addition to the one side (115a) of the first and second evaporators (115a, 115b), the refrigerant is also supplied to the other side (115b), and the refrigerant flows toward the compressor (111). Therefore, the refrigerant can be prevented from flowing from one side (115a) of the first and second evaporators (115a, 115b) to the other side (115b). Therefore, it is possible to prevent the lubricating oil contained in the refrigerant from stagnating on the other side (115b) of the first and second evaporators (115a, 115b).

  The invention described in claim 2 relates to a control method for defrosting the first and second evaporators (115a, 115b) in the refrigeration cycle apparatus (100), the technical significance of which is the above claim. 1 is essentially the same as the refrigeration cycle apparatus described in 1.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows a corresponding relationship with the specific means of embodiment description mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the present invention is applied to a refrigerator 1. As shown in FIG. 1, the freezer car 1 has a traveling engine 13 at the lower part of the cabin, and two freezing rooms (freezers) that allow different temperature settings at the rear part of the cabin, that is, the front freezing room. 11 and rear freezer compartment 12. Frozen foods such as frozen food and low-temperature refrigerated food (chilled food) are loaded into the freezer compartments 11 and 12 through open / close doors (not shown). Each freezer compartment 11, 12 is provided with a front temperature sensor 11a and a rear temperature sensor 12a for detecting the room temperature, and a room temperature signal detected by each of the temperature sensors 11a, 12a is a control unit 140 described later. Is output. The refrigeration cycle apparatus 100 (the compressor 111, the condenser 112, and the evaporators 115a and 115b as representative components are shown in FIG. 1) is mainly mounted on the front portion of the refrigeration vehicle 1 as described above. .

  FIG. 2 shows the overall configuration of the refrigeration cycle apparatus 100. The refrigeration cycle apparatus 100 includes a refrigeration cycle 110 provided with hot gas bypass passages 121 and 122 and a control unit 140. . In the refrigeration cycle 110, a compressor 111, a condenser 112, a receiver 113, first and second expansion valves 114a and 114b, first and second evaporators 115a and 115b, and an accumulator 116, which are arranged in parallel, are sequentially connected. It is a thing.

  The compressor 111 is a fluid machine that compresses and discharges the refrigerant in the refrigeration cycle 110 to a high temperature and a high pressure, and is driven by the engine 13 (FIG. 1) via an electromagnetic clutch 111a. That is, when the electromagnetic clutch 111a is energized, the driving force of the engine 13 is transmitted to the compressor 111, and the compressor 111 is driven. When the energization of the electromagnetic clutch 111a is interrupted, the driving force from the engine 13 is interrupted and the compressor 111 is stopped. Note that energization or de-energization of the electromagnetic clutch 111a is controlled by a control unit 140 described later.

  The condenser 112 is installed at a position in the vicinity of the under floor of the refrigerator 1 (FIG. 1) where it is easy to receive the traveling wind of the vehicle. The condenser 112 is blown by an electric condenser fan (not shown). It is a heat exchanger that cools the high-temperature and high-pressure refrigerant discharged from the compressor 111 to condense and liquefy with the cooling air.

  The receiver 113 separates the refrigerant condensed in the condenser 112 into a gas-phase refrigerant and a liquid-phase refrigerant, and causes only the liquid-phase refrigerant to flow out to the respective expansion valves 114a and 114b, and an excess liquid in the cycle. The phase refrigerant is stored inside.

  The first and second expansion valves 114a and 114b are decompression means for decompressing and expanding the liquid-phase refrigerant separated by the receiver 113. In this embodiment, the refrigerant is decompressed in an enthalpy manner and sucked into the compressor 111. A temperature type expansion valve that controls the throttle opening degree is employed so that the degree of superheat of the refrigerant to be set becomes a predetermined value.

  The first and second evaporators 115a and 115b are respectively disposed in the upper part of the freezer compartments 11 and 12 (FIG. 1), and absorb the heat by evaporating the refrigerant decompressed by the expansion valves 114a and 114b. It is a heat exchanger that exhibits an action (refrigeration function), and cools the air in the freezer compartments 11 and 12 by this endothermic action. A pipe extending downstream from the first evaporator 115a and a pipe extending downstream from the second evaporator 115b are laid along the freezer compartments 11 and 12, and are joined at a junction located at a predetermined part of the vehicle. They are connected to join. From this merging portion, a common pipe having a required length extends further downstream. This common pipe is laid along the freezer compartments 11 and 12 and the vehicle body, and is connected to an accumulator 116. As described above, the pipes extending from both the evaporators 115 a and 115 b merge before reaching the accumulator 116. Then, it reaches the accumulator 116 again via the piping.

  An electric evaporator fan (not shown) that is controlled by a control unit 140 described later is provided in a portion adjacent to each of the evaporators 115a and 115b. The evaporator fan sucks the air in the freezer compartments 11 and 12, passes through the evaporators 115 a and 115 b, and the cooling air cooled by the evaporators 115 a and 115 b enters the freezer compartments 11 and 12 again. It blows air, and the inside of each freezer compartment 11, 12 can be cooled with a uniform temperature distribution.

  Further, first and second temperature sensors 117a and 117b for detecting the temperature of the refrigerant flowing out from each of the evaporators 115a and 115b are provided on the refrigerant outflow side of each of the evaporators 115a and 115b. The refrigerant temperature signal detected at 117b is output to the control unit 140 described later.

  The accumulator 116 separates the refrigerant flowing out from each of the evaporators 115a and 115b into a gas-phase refrigerant and a liquid-phase refrigerant, causes only the gas-phase refrigerant to flow out to the compressor 111 side, and causes a liquid phase that becomes redundant in the cycle. The refrigerant is stored inside.

  The flow path between the receiver 113 and each expansion valve 114a, 114b is provided with first and second refrigeration solenoid valves 118a, 118b as opening / closing means for opening and closing the flow path, respectively. Opening and closing is controlled by a control unit 140 described later.

  The refrigeration cycle 110 is provided with first and second hot gas bypass passages 121 and 122 that bypass the condenser 112. That is, the hot gas bypass passages 121 and 122 directly communicate with the discharge side of the compressor 111 and the downstream side of the expansion valves 114a and 114b and the upstream side of the evaporators 115a and 115b, respectively. The first and second defrosting electromagnetic valves 131 and 132 as opening / closing means for opening and closing the flow paths are installed in the hot bypass flow paths 121 and 122, respectively. . Note that the opening and closing of the defrosting solenoid valves 131 and 132 is controlled by a control unit 140 described later.

  The control unit 140 includes computer means such as a microcomputer, and performs predetermined arithmetic processing (including the control map shown in FIG. 3) programmed in advance based on an input signal from an input terminal. Thus, the basic operation control of the refrigeration cycle 110 and the defrosting control using the hot gas bypass passages 121 and 122 are performed.

  The input terminal of the control unit 140 includes a refrigeration operation instruction signal from the occupant, a set temperature signal in each freezer compartment 11, 12 set by the occupant, a room temperature signal from each of the temperature sensors 11a, 12a, and each temperature sensor. Refrigerant temperature signals and the like from 117a and 117b are input. The set temperatures for the freezer compartments 11 and 12 can be arbitrarily set between 0 ° C. and −20 ° C., for example, the front freezer compartment 11 is −20 ° C., and the rear freezer compartment 12 is −5 ° C. Can be set (simultaneous freezing operation described later), or the front freezing chamber 11 can be set to -20 ° C. and the rear freezing chamber 12 can be set to a normal temperature (that is, no freezing operation instruction is issued) (freezing single operation described later).

  Meanwhile, the electromagnetic clutch 111a, the first and second refrigeration solenoid valves 118a and 118b, the first and second defrosting solenoid valves 131 and 132, a condenser fan (not shown), The evaporator fans are not connected, and the control unit 140 controls the operation of these devices based on the various signals.

  Next, the operation based on the above configuration and the operation and effect thereof will be described. The controller 140 is supplied with electric power when an ignition switch (not shown) of the vehicle is turned on. When the refrigeration operation instruction and the refrigeration set temperature are input from the occupant while the ignition switch is turned on, the control unit 140 performs the refrigeration operation so that the temperatures in the freezer compartments 11 and 12 become the set temperatures. Take control.

  Here, as shown in FIG. 3, the freezing operation includes a simultaneous freezing operation mode (No. 1) in which the freezing function of both evaporators 115a and 115b is exhibited according to the freezing set temperature of each freezer compartment 11 and 12, The refrigeration function of only one of the evaporators (115a or 115b) is exhibited (the other evaporator is the refrigeration function OFF), and the operation is divided into the single refrigeration operation mode (No. 3 or No. 5).

  In the simultaneous freezing operation mode, when the freezing operation instruction is input, the control unit 140 closes both the defrosting electromagnetic valves 131 and 132 and opens both the freezing electromagnetic valves 118a and 118b (in FIG. 3). No. 1), the electromagnetic clutch 111a is energized, the engine 13 and the compressor 111 are connected, and the compressor 111 is driven (ON). Then, the refrigerant from the compressor 111 passes through the condenser 112 and flows into both the evaporators 115a and 115b. Further, the control unit 140 activates (ON) the condenser fan and each evaporator fan, and starts cooling both freezer compartments 11 and 12 by both evaporators 115a and 115b. Control so that the temperature becomes the set temperature.

  On the other hand, in the case of the single refrigeration operation mode, the control unit 140 closes both the defrosting solenoid valves 131 and 132, and is connected to one evaporator (115a or 115b) that performs the refrigeration function. (118a or 118b) is opened (No3 or No5 in FIG. 3) so that the refrigerant from the compressor 111 flows into one evaporator (115a or 115b). Further, the control unit 140 activates (ON) the condenser fan and one evaporator fan, starts cooling one freezing chamber (11 or 12) by one evaporator (115a or 115b), The temperature in the freezer compartment (11 or 12) is controlled to be the set temperature.

  Next, defrosting operation control will be described. In the freezing operation of the freezer 1 as described above, the freezer compartment temperature is extremely low, such as −20 ° C. to −5 ° C., so that the freezer 1 is frequently opened in the freezer compartments 11 and 12 due to frequent opening of the door. When outside air containing moisture enters, frost adheres to each of the evaporators 115a and 115b. Due to the adhesion of frost, the refrigerating capacity of each of the evaporators 115a and 115b is lowered. Therefore, in the refrigeration cycle 110, it is necessary to perform defrosting operation control in order to remove frost attached to each of the evaporators 115a and 115b. In addition, in the defrosting operation, as shown in FIG. 3, the simultaneous defrosting operation mode (No2) corresponding to the simultaneous refrigeration operation mode and the single defrosting operation mode (No4 or No6) corresponding to the single refrigeration operation mode. And divided.

  Specifically, in the simultaneous defrosting operation mode, the control unit 140 determines that the temperature obtained from each of the temperature sensors 117a and 117b is the first predetermined temperature (for example, 0 ° C.) and starts the freezing operation (or during the previous defrosting operation). ), When both of the refrigeration solenoid valves 118a and 118b are closed, both the defrosting solenoid valves 131 and 132 are opened (No2 in FIG. 3). ). Further, the control unit 140 stops the condenser fan (the evaporator fan remains ON).

  Then, the refrigerant (hot gas) from the compressor 111 bypasses the condenser 112 and directly flows into the evaporators 115a and 115b from the hot gas bypass passages 121 and 122, and the evaporator 115a is caused by the hot gas. , 115b is defrosted. And if the temperature obtained from each temperature sensor 117a, 117b becomes the 2nd predetermined temperature (for example, 3 ° C), this simultaneous defrosting operation mode will be stopped and it will switch to the original simultaneous freezing operation mode (No1).

  On the other hand, in the single defrosting operation mode, the control unit 140 determines that the temperature obtained from the temperature sensor (117a or 117b) of the one evaporator (115a or 115b) that exhibited the refrigeration function is the first predetermined temperature ( For example, when it is determined that a predetermined time (for example, 1 hour) has elapsed since the start of the refrigeration operation (or during the previous defrost operation), both the refrigeration solenoid valves 118a and 118b are closed, The defrosting solenoid valves 131 and 132 are both opened (No. 4 or No. 6 in FIG. 3). That is, the defrosting solenoid valve (118b or 118a) connected to the other evaporator (115b or 115a) not exhibiting the refrigeration function is also opened in conjunction. Further, the control unit 140 stops the condenser fan and operates both the evaporator fans.

  Then, the refrigerant (hot gas) from the compressor 111 bypasses the condenser 112 and directly flows into the evaporators 115a and 115b from the hot gas bypass passages 121 and 122, and exhibits the refrigeration function by the hot gas. The defrosting in one evaporator (115a or 115b) is performed, and the hot gas returns to the compressor 111 via the accumulator 116. In addition, the hot gas which distribute | circulated the other evaporator (115b or 115a) which was not exhibiting the freezing function returns to the compressor 111 via the accumulator 116 similarly.

  As described above, in the present refrigeration cycle apparatus 100, the two evaporators 115a and 115b are provided so that the two freezer compartments 11 and 12 can be cooled to different set temperatures, and the hot gas bypass passages 131 and 132 are provided. Is provided so that defrosting can be performed in each of the evaporators 115a and 115b.

  Here, when performing the defrosting operation control in the single refrigeration operation mode, both the defrosting electromagnetic valves 131 and 132 are opened so that the refrigerant flows through both the hot gas bypass channels 121 and 122. In addition to one of the evaporators (115a or 115b) that exhibited the refrigeration function, the other evaporator (115b or 115a) that did not perform the refrigeration function was also supplied with a refrigerant, and the refrigerant was used as a compressor. It will flow toward 111. Therefore, the refrigerant can be prevented from flowing from one evaporator (115a or 115b) into the other evaporator (115b or 115a), and the lubricating oil contained in the refrigerant stagnates in the other evaporator (115b or 115b). Can be prevented.

  In this embodiment, the control unit 140 provides selective operation control means for selectively operating any of the plurality of evaporators, and simultaneous operation control means for simultaneously operating a plurality of evaporators among the plurality of evaporators. ing. Further, the control unit 140 provides defrost control means for heating the plurality of evaporators to such an extent that frost attached thereto can be removed. In this embodiment, the defrosting control means closes all the refrigeration solenoid valves and opens all the defrosting solenoid valves to defrost all the evaporators. This defrosting control means performs a common defrosting operation before the defrosting operation regardless of whether the control unit 140 functions as a selective operation control means or a simultaneous operation control means. At the same time. That is, a common defrosting operation is simultaneously provided to all the evaporators regardless of the operation state of the plurality of evaporators before the defrosting operation. In addition, the defrosting operation is performed by circulating a relatively high-temperature refrigerant through the refrigerant passage from the upstream side to the compressor located on the downstream side of all the evaporators. As a result, a merging section with a structure in which lubricating oil flows into and stagnates in some of the evaporators due to long-term selective operation downstream of a plurality of evaporators, or piping that is prone to stagnation of lubricating oil is installed. Even if it is made, the stagnation of the lubricating oil can be reduced at every defrosting operation.

(Other embodiments)
In the said 1st Embodiment, although demonstrated as what applied this invention to the freezer truck 1, it is applicable not only to this but the thing of other uses, such as a refrigerator.

It is the schematic which shows the freezing vehicle to which 1st Embodiment is applied. It is a mimetic diagram showing the whole refrigeration cycle device in a 1st embodiment. It is an operation | movement table (control map) which shows the action | operation of each solenoid valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Refrigeration cycle apparatus 110 Compressor 112 Condenser 114a 1st expansion valve (1st pressure reduction means)
114b Second expansion valve (second decompression means)
115a First evaporator 115b Second evaporator 121 First hot gas bypass passage 122 Second hot gas bypass passage 131 First defrosting solenoid valve (first opening / closing means)
132 Second defrosting solenoid valve (second opening / closing means)
140 Control unit

Claims (2)

A compressor (111) , a condenser (112) , a first and a second for opening and closing flow paths arranged in parallel between the outflow side of the condenser (112) and the suction side of the compressor (111) . Refrigeration opening / closing means (118a, 118b), first and second decompression means (114a, 114b), and first and second evaporators (115a, 115b), and by the compressor (111) In the refrigeration cycle (110) in which the refrigerant is circulated,
First and second hot gas bypass flows that bypass the condenser (112) from the compressor (111) and are connected to the inflow sides of the first and second evaporators (115a, 115b), respectively. Road (121, 122),
First and second opening / closing means (131, 132) for opening and closing the first and second hot gas bypass flow paths (121, 122), respectively;
When the operation control of the refrigeration cycle (110) and defrosting in the first and second evaporators (115a, 115b) are required, the first and second hot gas bypass flow paths (121, 122) are used. In the refrigeration cycle apparatus provided with a control unit (140) for performing opening / closing control of the first and second opening / closing means (131, 132) in order to form the refrigerant flow to the) side,
The controller (140) closes both the first and second opening / closing means (131, 132), and one of the first and second refrigeration opening / closing means (118a, 118b). open the closing means (118a), the first closing the other frozen for opening and closing means (118b), a second evaporator (115a, 115b) of, whereas the side evaporator only frozen function (115a) When the single refrigeration operation to be performed is performed, the first and second refrigeration opening and closing means ( when the defrost operation is performed because the defrosting in the evaporator (115a) on one side is necessary) 118a, 118b) are closed together, and the first and second opening / closing means (131, 132) are both opened , and the refrigeration function is provided from the first and second hot gas bypass channels (121, 122). The one side that was showing In addition to the evaporator (115a), the refrigeration cycle apparatus characterized by supplying a coolant to said did not exhibit the refrigeration function other side of the evaporator (115b). A compressor (111) , a condenser (112) , a first and a second for opening and closing flow paths arranged in parallel between the outflow side of the condenser (112) and the suction side of the compressor (111) . Refrigeration opening / closing means (118a, 118b), first and second decompression means (114a, 114b), and first and second evaporators (115a, 115b), and by the compressor (111) In the refrigeration cycle (110) in which the refrigerant is circulated,
First and second hot gas bypass flows that bypass the condenser (112) from the compressor (111) and are connected to the inflow sides of the first and second evaporators (115a, 115b), respectively. Road (121, 122) ,
First and second opening / closing means (131, 132) for opening and closing the first and second hot gas bypass flow paths (121, 122), respectively, are provided;
When defrosting is required in the first and second evaporators (115a, 115b) while controlling the operation of the refrigeration cycle (110), the first and second hot gas bypass channels ( 121, 122) a refrigeration cycle apparatus control method for controlling opening and closing of the first and second opening / closing means (131, 132) in order to form the refrigerant flow to the side,
Both the first and second opening / closing means (131, 132) are closed, and one of the first and second refrigeration opening / closing means (118a, 118b) is opened. said first closed other frozen-off means (118b), a second evaporator (115a, 115b) of, whereas performed alone freezing operation to exert a refrigeration function only on a side evaporator (115a) The first and second refrigeration opening / closing means (118a, 118b) are both closed when the defrosting is required in the evaporator (115a) on the one side and the defrosting operation is performed. The one side where the first and second opening / closing means (131, 132) are opened together and the refrigeration function is exerted from the first and second hot gas bypass flow paths (121, 122). Added to the evaporator (115a) Te, the control method of the refrigeration cycle apparatus characterized by supplying a coolant to said did not exhibit the refrigeration function other side evaporator (115b).

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