JPH08150828A - Air conditioner - Google Patents

Abstract

PURPOSE: To dispense with an oil separator, an oil cooler and a return oil pipe by altering each of two compressors into a mist circulating type compressor made up of doing lubrication by means of an oil mist contained in the cooling medium gas, in this air conditioner provided with these two compressors parallelly built in a refrigerant circuit. CONSTITUTION: A car air conditioner is provided with two compressors 1 and 2 being driven by an engine via two electromagnetic clutches 1c and 2c, and it feeds an evaporator 9 with a gas cooling medium discharged out of these compressors 1 and 2 via a condenser 4, a receiver 6, a dryer 7 and an expansion valve 8, and hereat it cooled the room air to be ventilated by a fan 10. In this case, both these compressors 1 and 2 are altered into a mist circulating type compressor being lubricated by an oil mist contained in the cooling medium gas. Subsequently, the oil mist in an amount corresponding to a circulation quantity of the cooling medium is put back to the compressors 1 and 2, and these compressors 1 and 2 can be sufficiently lubricated, dispensing with the conventional oil separators and oil coolers and so on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner mounted on buses, trucks and passenger cars.

[0002]

2. Description of the Related Art A system diagram of a conventional air conditioner is shown in FIG. When the forced lubrication type compressors 1 and 2 are driven by the running engine (not shown) via the electromagnetic clutches 1c and 2c, the gas refrigerant discharged from these compressors 1 and 2 joins via the discharge pipes 1a and 2a. , Enters the oil separator 3, where the oil contained in the gas refrigerant is separated. The separated oil is passed through the oil cooler 10 and the oil return pipes 11a and 11b to the compressors 1 and 2
Is returned to.

The gas refrigerant flowing out from the oil separator 3 enters the condenser 4, where it is condensed and liquefied by radiating heat to the outside air blown by the fan 5. Next, this liquid refrigerant enters the expansion valve 8 via the receiver 6 and the dryer 7,
When it is squeezed here, it adiabatically expands. This refrigerant enters the evaporator 9 where it cools the air in the passenger compartment blown by the fan 10 to evaporate it. Next, this gas refrigerant is sucked into the compressors 1 and 2 through the suction pipes 1b and 2b.

The compressors 1, 2 are set according to the load calculated from the room temperature set value, the number of passengers in the passenger compartment, the outside air temperature, the amount of solar radiation, etc.
And the number of revolutions of the compressor in operation are controlled.

[0005]

In the above conventional air conditioner, the compressors 1 and 2 are forcibly lubricated, so that the oil separated by the oil separator 3 is separated from the oil cooler 10 and the oil return pipe 11a. Need to go back to compressors 1 and 2 via 11b,
Therefore, there is a problem that the structure is complicated, the weight is increased, and the cost is increased.

Further, since the amount of oil returned from the oil separator 3 to each of the compressors 1 and 2 is not equal due to various pressure loss differences, the oil discharged from the compressors 1 and 2 along with the refrigerant gas is discharged. There is a risk that the amount of oil and the amount of returned oil do not match, and therefore the oil surfaces in the compressors 1 and 2 become non-uniform, causing poor lubrication.

When the load is low, the compressor 1 stops, but when the stop time becomes long, oil gradually accumulates in the stopped compressor 1 and the amount of oil in the running compressor 2 decreases. For,
There is a possibility that this lubrication failure of the compressor 2 and a seizure accident due to this may occur. Then, when the stopped compressor 1 is restarted, the compressor 1 may be damaged by an excessive impact due to the oil compression.

[0008]

The present invention has been invented to solve the above-mentioned problems, and its gist is to provide a plurality of compressors installed in parallel in a refrigerant circuit. In the air conditioner described above, the plurality of compressors are mist lubricated compressors lubricated by oil mist contained in the refrigerant gas.

Another feature is that, when at least one of the plurality of compressors is stopped, the stopped one compressor is set to a predetermined short time at a predetermined set time. There is a means to drive only for hours.

Still another feature is that, when only one of the plurality of compressors is operated at a low speed, the plurality of compressors are set to a predetermined short time at a predetermined set time. There is a means to drive at high speed only for the time.

[0011]

In the present invention, since each of the plurality of compressors is lubricated by the oil mist contained in the refrigerant gas,
Eliminates oil separator, oil cooler and oil return pipe.

When at least one of the plurality of compressors is stopped according to the load, the stopped compressor is operated for a predetermined short time every preset time.

When only one of the plurality of compressors is operated at a low speed, the plurality of compressors are operated at a high speed for a predetermined short time every preset time.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT One embodiment of the present invention is shown in FIGS. As shown in FIG. 1, each of the compressors 1 and 2 is a mist lubrication type compressor that is lubricated by an oil mist contained in a refrigerant gas. Therefore, the amount of oil mist corresponding to the circulation amount of the refrigerant returns to the compressors 1 and 2, and the compressors 1 and 2 can be sufficiently lubricated by the oil mist, so that the conventional oil separator 3 and the oil cooler 10 are provided. The oil return pipes 11a and 11b are omitted.

A sensor 19 for detecting the rotation of the compressor 1.
Is provided, and the detection value of the sensor 19 is input to the controller 30. Then, by turning on / off the electromagnetic clutches 1c and 2c according to a command from the controller 30, the compressors 1 and 2 are operated / stopped. Other configurations are similar to those of the conventional one shown in FIG. 5, and corresponding members are designated by the same reference numerals.

The electrical control circuitry of controller 30 is shown in FIG. When the sensor 19 detects that the compressor 1 has stopped, the contact 19a becomes a contact and the timer 20 is energized,
Timer 20 starts counting. When a preset time, for example, 10 minutes, has elapsed in the timer 20, the timer 20 times out and the time-delaying contact 20a comes into contact.

Then, the timer 21 is energized and starts counting, and at the same time, the time-delaying contact 21a is brought into contact. This excites the relay 22 and its contact 22a
Are contacted with each other, the electromagnetic clutch 1c of the compressor 1 is excited and contacted, and the compressor 1 is started.

When a preset time of the timer 21, for example, 5 seconds has elapsed, the timer 21 is timed up,
The time-delayed operation contact 21a is opened, and the time-delayed operation contact 21b is in contact.

When the contact 21a is opened, the relay 22
Is demagnetized and its contact 22a opens, the electromagnetic clutch
1c is demagnetized and disconnected, and the compressor 1 stops.

Then, while the compressor 1 is stopped, it is 5 every 10 minutes.
Since the compressor 1 is operated only for a second, it is possible to prevent the oil from accumulating in the compressor 1, and as a result, the lubrication failure of the compressor 2 during operation or the seizure accident due to it can be prevented. In addition, it is possible to prevent damage due to liquid compression when the compressor 1 is restarted.

A second embodiment of the invention is shown in FIGS. As shown in FIG. 3, a rotation speed sensor 31 that detects the rotation speed of the compressor 2 is installed.
The output of is also input to the controller 32. The controller 32 consists of a micro computer,
It outputs to the drive motor 1M of the compressor 1 and the drive motor 2M of the compressor 2 to control their operation or stop and the rotation speed. The other structure is the same as that of the first embodiment shown in FIG.
Corresponding members are given the same reference numerals.

A control flowchart of the controller 32 is shown in FIG. As shown in FIG. 4, when the operation of the air conditioner is started, it is confirmed in step whether or not one compressor is operating, that is, whether or not the compressor 1 is stopped. If not, the process returns to the step, but in that case, it is confirmed whether or not the compressor 2 in operation is in the low speed rotation range in the step.

If the answer is NO, the process returns to the step, but if the answer is YES, it is confirmed whether or not the operation in the low speed rotation region has passed a set time (for example, 10 minutes). The compressors 1 and 2 are operated simultaneously and rotate at high speed.

Then, in steps, a set time (for example, 5
It is confirmed whether or not (second) has elapsed, and when it has elapsed, the compressor 1 is stopped in a step and only the compressor 2 is returned to the low speed operation.

However, in the second embodiment, while only the compressor 2 is operating in the low speed rotation range, the compressors 1 and 2 are operated at high speed for 5 seconds every 10 minutes, and the flow rate of the refrigerant circulating in the refrigerant circuit is increased. Therefore, the oil that has adhered and accumulated on the inner surfaces of the evaporator 9 and the suction pipe 2b returns to the compressors 1 and 2 along with the refrigerant gas.

Therefore, when only the compressor 2 is returned to the low speed operation, the oil mist returning to the compressor 2 accompanying the intake refrigerant gas increases, so that the lubrication failure of the compressor 2 and the seizure accident due to it are prevented. it can.

[0027]

According to the present invention, since the plurality of compressors are lubricated by the oil mist contained in the refrigerant gas, the oil separator, the oil cooler and the oil return pipe are unnecessary. Therefore, the structure is simplified, and the weight and cost can be reduced.

When at least one of the plurality of compressors is stopped, if one compressor that is stopped is operated at a predetermined set time for a predetermined short time, the operating compression It is possible to prevent poor lubrication of the machine and seizure accidents due to this, and also to prevent damage to the compressor due to liquid compression when the stopped compressor is restarted.

When only one of the plurality of compressors is operated at a low speed, if a plurality of compressors are operated at a high speed for a predetermined short time every predetermined set time, the compressor is operated at a low speed. Insufficient lubrication of the compressor and seizure accident due to this can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is an electrical control circuit diagram of the first embodiment.

FIG. 3 is a system diagram showing a second embodiment of the present invention.

FIG. 4 is a control flow chart of a second embodiment.

FIG. 5 is a refrigerant circuit diagram of a conventional air conditioner.

[Explanation of symbols]

 1, 2 Compressor 4 Condenser 8 Expansion valve 9 Evaporator 19 Rotation sensor 30 Controller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumasa Hayakawa No. 1 Takamichi, Iwazuka-cho, Nakamura-ku, Nagoya City Mitsubishi Heavy Industries, Ltd. Nagoya Research Institute (72) Inventor Kazuhiro Otsuka Asahi-cho, Nishibiwajima-cho, Nishikasugai-gun, Aichi Prefecture Sanchome No. 1 Mitsubishi Heavy Industries, Ltd. Air Conditioning Factory

Claims (3)

[Claims] 1. An air conditioner comprising a plurality of compressors installed in parallel in a refrigerant circuit, wherein the plurality of compressors are lubricated by an oil mist contained in a refrigerant gas. An air conditioner characterized in that 2. When at least one of the plurality of compressors is stopped, a means for operating the stopped one compressor for a predetermined short time every predetermined time is set. The air conditioner according to claim 1, wherein the air conditioner is provided. 3. When only one of the plurality of compressors is operated at a low speed, the plurality of compressors are operated at a high speed for a predetermined short time at each predetermined set time. The air conditioner according to claim 1, further comprising means.