JP2002089977A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an air conditioner for vehicle, which is capable of securing sufficient amount of refrigerant and lubricating oil in the side of a compressor under operation by sucking the refrigerant in a stopped evaporator by the compressor under operation. SOLUTION: The air conditioner for vehicle is provided with a refrigerating cycle C, in which a plurality of series circuits, connecting expansion valves 3a, 3b, 3c, evaporators 2a, 2b, 2c and compressors 1a, 1b, 1c, are connected in parallel while the plurality of series circuits, a condenser 4 and a liquid receiver 5 are connected sequentially through refrigerant pipeline 8. In such an air conditioner for vehicle, the suction part sides of refrigerant for respective compressors 1a, 1b, 1c are connected by capillaries 11a, 11b, 11c having the function of pressure reducing to suck staying refrigerant and lubricating oil in the stopping evaporators 2a, 2b, 2c by the remaining operating compressors 1a, 1b, 1c when at least one set among the compressors 1a, 1b, 1c is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner comprising a plurality of evaporators and compressors connected in parallel by a refrigerant pipe, and more particularly to a lubricating oil return structure in a refrigeration cycle.

[0002]

2. Description of the Related Art For example, in a vehicle air conditioner applied to a two-story bus vehicle, a large amount of cooling capacity is required. Therefore, two or three independent refrigeration cycles are formed respectively. Although it is generally in the form,
These independent refrigeration cycles have drawbacks in that the refrigerant piping becomes complicated, and a plurality of functional components such as a condenser and a liquid receiver are required, resulting in an increase in cost.

In order to solve the above-mentioned high cost, a plurality of evaporators and a plurality of compressors are used.
It is known that other functional components are configured as a single unit and correspond to one refrigeration cycle. As shown in FIG. 3, two series circuits including compressors 100a and 100b and evaporators 110a and 110b and expansion valves 120a and 120b are connected in parallel, and condensers 130 and 100b are sequentially arranged from the discharge side of the compressors 100a and 100b. One refrigeration cycle is provided by the refrigerant pipe 160 in the order of the liquid receiver 140 and the dryer 150.

[0004] One evaporator 110a and one expansion valve 120a are accommodated in, for example, an air-conditioning unit installed in the vehicle cabin on the first floor, and the other evaporator 110b and the other expansion valve 120b are mounted on the second floor. This is a vehicle air conditioner that is housed in an air conditioning unit installed in a passenger compartment of the vehicle and air-conditions the passenger compartment of a two-story bus vehicle.

In the above-described vehicle air conditioner, it is possible to select a simultaneous operation in which both compressors 100a and 100b are driven or a single operation in which only one of them is driven. Reference numeral 150 denotes a dryer that removes moisture contained in the refrigerant circulating in the refrigeration cycle.

[0006]

However, in the conventional vehicle air conditioner described above, the compressors 100a, 100
This does not pose a problem during the simultaneous operation of driving both of the b.
In the one-way operation in which only the floor compressor 100b is driven, the liquefied refrigerant concentrates in the evaporator 110a in which the refrigerant does not circulate, and the refrigerant required by the driven compressor 100b due to the accumulation of lubricating oil. There is a problem that the amount and lubricating oil amount are insufficient.

That is, the evaporator 110 in which the refrigerant does not circulate.
On the a side, a liquefied refrigerant is generated in the evaporator 110a because the temperature is relatively lower than other parts in the refrigeration cycle. This liquefied refrigerant is supplied with refrigerant from another part and liquefaction proceeds, and since the lubricating oil contained in these refrigerants also stays, the refrigerant required for the driven compressor 100b is Insufficient refrigerant and lubricating oil levels can cause problems such as insufficient refrigerant capacity, abnormal compressor wear, and locking.

Further, when the stopped compressor 100a is operated, there is also a problem that the liquid refrigerant which has accumulated in the evaporator 110a is sucked to cause liquid compression.

In view of the above, an object of the present invention is to provide
When at least one of the plurality of compressors is stopped, the refrigerant on the evaporator side where the refrigerant does not circulate is sucked by the driven compressor, so that a sufficient amount of refrigerant and lubrication are provided on the driven compressor side. An object of the present invention is to provide a vehicle air conditioner capable of securing oil.

[0010]

In order to achieve the above object, the technical means according to claims 1 and 2 are adopted.

That is, according to the first aspect of the present invention, the pressure reducing device (3a, 3b, 3c) and the evaporator (2a, 2b, 2c)
A plurality of series circuits connecting the compressor and the compressors (1a, 1b, 1c) are connected in parallel, and a plurality of series circuits, a condenser (4), and a liquid receiver (5) are arranged in the refrigerant pipe (8) in this order. In a vehicle air conditioner equipped with a connected refrigeration cycle (C), the refrigerant suction side of each compressor (1a, 1b, 1c) has a pipe (11a, 11b, 1) having a decompression function.
1c) and the compressors (1a, 1b, 1c)
When at least one of the compressors is stopped, the compressor (1a, 1b, 1c) being driven is used to remove the refrigerant remaining on the side of the evaporator (2a, 2b, 2c) where the refrigerant does not circulate. 11a, 11b, 11c).

According to the first aspect of the invention, the evaporator (2a, 2b, 2c) through which the refrigerant does not circulate and the suction side of the driven compressor (1a, 1b, 1c) have a pressure reducing function. (11a, 11b, 11c), the evaporator (2a, 2b, 2c) in which the refrigerant does not circulate
The refrigerant staying in the parentheses can be sucked.

Therefore, the driven compressors (1a, 1a,
b, 1c), a required amount of refrigerant and lubricating oil are circulated, thereby causing insufficient cooling capacity and the compressors (1a, 1b, 1c).
Abnormal wear and lock and other problems do not occur.

Further, since the connected pipes have a pressure reducing function such as a pressure reducing valve, the driven compressors (1a, 1b, 1c) do not suck the liquid refrigerant, so that the liquid compression is prevented. Can be achieved.

Further, a plurality of evaporators (2a, 2b, 2c)
) And a plurality of compressors (1a, 1b, 1c) to constitute one refrigeration cycle (C),
Since the condenser (4) and the liquid receiver (5) can be configured as a single unit, the refrigeration cycle (C) is simplified, and
Cost reduction can be achieved.

According to a second aspect of the present invention, the pipes (11a, 11b, 11c) having a pressure reducing function are constituted by capillary tubes (11a, 11b) having a fixed throttle resistance.

According to the second aspect of the present invention, by using the capillary tubes (11a, 11b), a low-cost fixed throttle can be formed, and the stationary evaporators (2a, 2b, 2c) are driven. Compressor (1a,
1b and 1c) can communicate with the suction side, so that no stagnant refrigerant is generated and liquid compression can be prevented.

Note that the reference numerals in parentheses of the above means indicate the correspondence with specific means of the embodiment described later.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a vehicle air conditioner of the present invention is applied to, for example, a two-story bus vehicle will be described below with reference to FIG. First, three compressors 1a, 1
b, 1c and three evaporators 2a, 2
b, 2c, and the respective suction sides of the three evaporators 2a, 2b, 2c and the expansion valve 3
a, 3b, and 3c are connected to the respective outflow sides.

That is, the compressor 1a, 1b, 1c, the evaporators 2a, 2b, 2c and the expansion valves 3a, 3b, 3c are connected in parallel in three series circuits.

From the branch points A to 3 where the high-pressure refrigerant is diverted to the respective suction sides of the three expansion valves 3a, 3b and 3c.
Refrigerant paths of three systems (functional components are arranged in parallel) are formed to a junction B where the high-pressure refrigerant flowing out from the discharge sides of the compressors 1a, 1b, and 1c merges.

Then, from the junction B on the discharge side of the compressors 1a, 1b, 1c, the condenser 4, the liquid receiver 5, the supercooling heat exchanger 6, the drying member 7, and the suction side of the expansion valves 3a, 3b, 3c. One refrigeration cycle C connected by the refrigerant pipes 8 in the order of the branch points A.

Of the three evaporators 2a, 2b and 2c, the evaporator 2a is housed in an air conditioning unit (not shown) for air-conditioning the passenger compartment on the first floor, and the conditioned air is blown on the first floor by an indoor blower 9a. It blows out into the cabin. The remaining evaporators 2b and 2c are housed in an air-conditioning unit (not shown) for air-conditioning the vehicle interior on the second floor, and blow air-conditioned air into the vehicle interior on the second floor by the blower 9b.

The expansion valves 3a, 3b and 3c are well-known thermal expansion valves which detect the refrigerant temperature at the outlet pipe side of the evaporators 2a, 2b and 2c and adjust the valve opening to adjust the flow rate of the refrigerant. And is housed in the above-described air conditioning unit (not shown) in which the evaporators 2a, 2b, and 2c are housed.

The supercooling heat exchanger 6 further cools the refrigerant flowing out of the condenser 4 and increases the degree of supercooling of the refrigerant to improve the coefficient of performance.

Reference numeral 10 denotes an outdoor blower for releasing heat of condensation of the condenser 4 and the supercooling heat exchanger 6. Drying member 7
Is a desiccant for removing water contained in the refrigerant circulating in the refrigeration cycle C.

Next, the main part of the present invention will be described. Capillary tubes 11a and 11b having a decompression function are formed so as to be connected to the suction sides of the compressors 1a, 1b and 1c, respectively. This capillary tube 11a,
Reference numeral 11b denotes a tube having a fixed throttle, which is arranged in a system on the side of the stopped compressors 1a, 1b, 1c when one or two of the three compressors 1a, 1b, 1c are stopped. The liquefied refrigerant generated in the stopped and stopped evaporators 2a, 2b, 2c is driven by the compressors 1a, 1b,
The refrigerant is sucked into the side 1c, and the refrigerant liquefied by being decompressed by the fixed throttle is gasified and sucked. Therefore, it is configured such that the liquid refrigerant does not enter the suction sides of the compressors 1a, 1b, 1c.

Next, the operation of the vehicle air conditioner having the above configuration will be described. First, an operation switch (not shown) for the first and second floors is provided in an operation panel (not shown), and air conditioning is performed on both the first and second floors by operating the operation switches (not shown). Simultaneous operation for driving and one operation for selecting either the first floor or the second floor can be performed.

Therefore, when the occupant selects the simultaneous operation in which the operation switches (not shown) for the first floor and the second floor are operated, the operation of the three compressors 1a, 1b, 1c is started and the compressors are started. As shown in FIG. 1, the high-pressure refrigerant from the discharge side of 1a, 1b, 1c is circulated in the direction of the arrow from the junction B, the evaporators 2a, 2b, 2c are cooled, and the indoor blower 9a, By 9b, the air-conditioning operation is performed so that the vehicle interiors of the first and second floors have a separately selected set temperature.

Next, when the occupant operates one of the first- and second-floor operation switches (not shown) for one operation, for example, to operate only the second floor, the compressor 1a, the evaporator The system on the side of the compressor 2a and the indoor blower 9a is stopped, and the system on the side of the compressors 1b and 1c, the evaporators 2b and 2c, and the indoor blower 9b is operated. The high-pressure refrigerant discharged from the two driven compressors 1b and 1c is circulated mainly from the junction B to the evaporators 2b and 2c, so that only the interior of the vehicle on the second floor is set to a separately selected set temperature. The air-conditioning operation is performed as follows.

However, in this one-way operation, part of the refrigerant also enters the evaporator 2a side where the refrigerant does not circulate. That is, in the evaporator 2a in which the refrigerant does not circulate, the temperature is relatively lower than the remaining evaporators 2b and 2c, and the refrigerant liquefies and starts to stagnate, but the compressor 1b in which the capillary tubes 11a and 11b are driven. 1c, the refrigerant in the evaporator 2a is sucked into the compressors 1b, 1c which are driven without stagnation.

When the cabin temperature on the second floor reaches the set temperature, one of the driven compressors 1b and 1c stops its operation and performs room temperature control. Since the capillary tubes 11a and 11b are connected to the suction sides of the driven compressors 1b and 1c (one of them), the evaporator 2 in which the refrigerant does not circulate
No stagnant refrigerant is generated in the b, 2c (either one) side.

According to the vehicle air conditioner in the above embodiment, the three compressors 1a are connected by connecting the suction sides of the compressors 1a, 1b, 1c with the capillary tubes 11a, 11b having a pressure reducing function. When one or two of the compressors 1b and 1c are stopped, the evaporator 2 is disposed in the system of the stopped compressor 1a and does not circulate the refrigerant.
a can be sucked by the remaining driven compressors 1b and 1c without stagnation, so that the amount of refrigerant and the amount of lubricating oil contained in the refrigerant can be reduced by the driven compressors 1b and 1c. Good air-conditioning operation is possible without running out.
Therefore, problems such as insufficient cooling capacity, abnormal wear of the compressors 1a, 1b, and 1c and locks do not occur.

Further, by connecting the capillary tubes 11a and 11b having a decompression function, the driven compressors 1b and 1c do not suck the liquid refrigerant, so that the liquid compression can be prevented.

Further, by connecting three series circuits consisting of three compressors 1a, 1b, 1c and three evaporators 2a, 2b, 2c in parallel to constitute one refrigeration cycle C, Condenser 4, liquid receiver 5, and supercooling heat exchanger 6
Since the refrigerant pipe 8 of the refrigeration cycle C can be simplified, the cost can be reduced by minimizing the number of functional components.

(Other Embodiments) In the above embodiment, 3
Compressors 1a, 1b, 1c and three evaporators 2a,
Although the description has been given as a vehicle air conditioner in which three series circuits 2b and 2c are connected in parallel to constitute one refrigeration cycle C, the present invention is not limited to this. As shown in FIG. One refrigeration cycle C may be configured by connecting two series circuits consisting of 1a, 1b and two evaporators 2a, 2b in parallel.

Further, the suction side of each of the compressors 1a, 1b, 1c is provided with a capillary tube 11a, 1
Although the connection is made using 1b, a pressure reducing connection pipe 11c having a pressure reducing valve 11d may be used as shown in FIG.

Further, in the above embodiment, the embodiment in which the refrigeration cycle C of the present invention is applied to an air conditioner of a two-story bus vehicle has been described, but a plurality of compressors 1a, 1b,
1c and the refrigeration cycle C in which the evaporators 2a, 2b, and 2c are arranged in parallel may be used, and the present invention is also applicable to an air conditioner that air-conditions a plurality of zones in a vehicle compartment.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a refrigeration cycle of a vehicle air conditioner according to an embodiment of the present invention.

FIG. 2 is an overall configuration diagram illustrating a refrigeration cycle of a vehicle air conditioner according to another embodiment.

FIG. 3 is an overall configuration diagram showing a refrigeration cycle of a vehicle air conditioner according to the related art.

[Explanation of symbols]

 1a ... Compressor 1b ... Compressor 1c ... Compressor 2a ... Evaporator 2b ... Evaporator 2c ... Evaporator 3a ... Expansion valve (decompression device) 3b ... Expansion valve (decompression device) 3c ... Expansion valve (decompression device) 4 ... Condenser 5 ... Receiver 8 ... Refrigerant pipe 11a ... Capillary tube (Pipe with decompression function) 11b ... Capillary tube (Pipe with decompression function) 11c ... Decompression connection pipe (Pipe with decompression function) C ... Refrigeration cycle

Claims (2)

[Claims] 1. A pressure reducing device (3a, 3b, 3c), an evaporator (2a, 2b, 2c) and a compressor (1a, 1b, 1c).
) Are connected in parallel, and a refrigeration cycle (C) in which a plurality of series circuits, a condenser (4) and a liquid receiver (5) are connected in this order by a refrigerant pipe (8). The refrigerant | coolant suction part side of each said compressor (1a, 1b, 1c) is provided with the piping (11a, 11b, 11
c) and the compressors (1a, 1b, 1c)
), When at least one of the compressors is stopped, the compressor (1a, 1b, 1c) being driven is used to reduce the refrigerant remaining on the evaporator (2a, 2b, 2c) side where the refrigerant does not circulate. Piping (11a, 11b,
11c). 2. A pipe (11a, 1) having a pressure reducing function.
2. The vehicle air conditioner according to claim 1, wherein each of 1b and 11c) includes a capillary tube (11a and 11b) having a fixed throttle resistance. 3.