JPH0942791A - Freezer device and air conditioner with this freezer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a burning of a winding of an electric motor for a compressor to be prevented even if no expansion valve is present in an outdoor device by a method wherein a plurality of indoor devices are connected to the outdoor device and a degree of opening of the expansion valve of each of the indoor devices is increased when a temperature of refrigerant discharged from the compressor is increased more than a predetermined value. SOLUTION: An air conditioner 1 is comprised of a plurality of indoor devices A1, A2, a plurality of outdoor devices B and an inter-device piping 2 for connecting these devices. The indoor devices A1, A2 store an indoor heat exchanger 3 and an indoor fan. The indoor heat exchanger 3 is provided with a control valve 4. As a load applied to compressors 5, 6 is varied in response to a variation of load to be air conditioned, a temperature of the refrigerant discharged from the compressors 5, 6 is changed, so that this change is detected by a sensor 15. Then, if this temperature is more than a predetermined value, a winding of an electric motor for each of the compressors 5, 6 is apt to be burnt, so that a degree of opening of a control valve 4 in the indoor device being operated is set to be higher than the present degree of opening.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an outdoor unit having a compressor and an outdoor heat exchanger built therein, and a plurality of indoor units having an expansion valve and an indoor heat exchanger built therein connected by unit piping. The present invention relates to a separate type refrigeration system (air conditioner).

[0002]

2. Description of the Related Art Japanese Patent Publication No. 4-29945 discloses a so-called multi-type air conditioner. In this publication, a so-called decompressor (expansion valve) is not incorporated in the outdoor unit, but a decompressor is incorporated only in each indoor unit. Then, by arbitrarily adjusting the valve opening degree of the pressure reducer of each indoor unit, the oil sump generated in each indoor unit is eliminated, and the lack of lubricating oil in the compressor is less likely to occur.

[0003]

In such a multi-type air conditioner, when the temperature of the refrigerant discharged from the compressor in the outdoor unit becomes abnormally high due to fluctuations in the air conditioning (refrigeration) load, etc. There is. By the way, since such an outdoor unit does not have an expansion valve as in the prior art, it is impossible to suppress the above-mentioned abnormal increase in the refrigerant temperature, and it is conceivable that the winding of the electric motor of the compressor is burned out.

Therefore, the present invention has an object to prevent the winding of the electric motor of the compressor from being burnt out even if the expansion valve does not exist in the outdoor unit.

[0005]

In order to achieve this object, the first aspect of the present invention is such that an expansion valve and an indoor heat exchanger are incorporated in an outdoor unit in which a compressor and an outdoor heat exchanger are incorporated. A plurality of indoor units are connected by unit piping, and when the temperature of the refrigerant discharged from this compressor reaches or exceeds a predetermined value, the opening degree of the expansion valve of the indoor unit is increased.

A second aspect of the present invention is an inter-unit piping in which an outdoor unit having a variable capacity compressor and an outdoor heat exchanger is incorporated into an outdoor unit having an expansion valve and an indoor heat exchanger incorporated therein. When the temperature of the refrigerant discharged from the variable capacity compressor reaches or exceeds a predetermined value, control to increase the valve opening of the expansion valve of the indoor unit is given priority over the capacity control of this compressor. It is something to do.

According to a third aspect of the invention, when the refrigerant discharge temperature of the compressor exceeds a predetermined value, the degree of opening of the expansion valve of the indoor unit is adjusted according to the length of the inter-unit piping. To do.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a separate type air conditioner of the present invention, in which an air conditioner 1 comprises a plurality of indoor units A1 and A2, an outdoor unit B, both units A1,
It is composed of an inter-unit pipe 2 connecting A2 and B. Each of the indoor units A1 and A2 incorporates an indoor heat exchanger 3 that functions as an evaporator during cooling operation and a condenser during heating operation, and an indoor fan (not shown). Further, the indoor heat exchanger 3 is provided with a control valve (mechanical valve) 4 in each of the indoor units A1 and A2. The control valve 4 is closed to stop the inflow of the refrigerant when the indoor units A1 and A2 are not operated, and the opening of the valve is adjusted so that the refrigerant inflow amount according to the load is controlled. Has become.

Two outdoor units B are connected in parallel.
Two compressors (compressors) 5 and 6 are provided, and the capacity of the compressor and the like is controlled in response to a control signal from the controller 17 (described later). In the outdoor unit B,
A four-way valve 7, an outdoor heat exchanger 8 that acts as a condenser during cooling operation and an evaporator during heating operation, and an accumulator 9 are incorporated.

Further, in this embodiment, the tube diameter of the indoor heat exchanger 3 and the outdoor heat exchanger 8 of the outdoor unit B is about 7 mm, which is smaller than the normal diameter (diameter about 9 mm). It is inexpensive and has a small capacity. A tube with such a small diameter is used. As a result, the capacity of the refrigerant circuit on the side of the indoor units A1, A2 can be reduced, and the amount of refrigerant to be sealed can be reduced accordingly.

In the entire refrigerant circuit of the air conditioner 1, the so-called pressure reducer (expansion valve) is an indoor unit A.
Only the control valves 4 for A1 and A2 are provided, and the receiver tank and the like which have been conventionally required are not arranged. An accumulator 9 is connected to each of the two compressors 5 and 6 on the suction side, and an oil separator 10 is connected to the discharge side.
Is connected. In this embodiment, one compressor 5 has a power of 4 horsepower, and the other compressor 6 has a power of 6 horsepower.

The two compressors 5 and 6 are so-called rated compressors whose power consumption frequency is constant,
One compressor (the one with less horsepower)
5 has a built-in power save mechanism, which saves the output by about 50% and makes the discharge amount variable. Further, a refrigerant return mechanism 13 is provided for returning a part of the refrigerant from the discharge pipes 11 discharged from both the compressors 5 and 6 to the suction pipe 12 on the refrigerant suction side of the compressor.

The refrigerant return mechanism 13 is arranged so that the discharge pipes 11 of both rated compressors 5, 6 are connected to both compressors 5, 5.
A part of the discharged refrigerant is returned to the suction pipe 12 of No. 6, and a part of the discharged refrigerant is returned to the accumulator 9 by opening the return valve 14 provided in the return mechanism (return pipe) 13. There is. The refrigerant return mechanism 13 of this embodiment saves the output of one horsepower.

By combining the variable capacity control by the compressors 5 and 6 and the opening / closing of the return valve 14 of the refrigerant return mechanism 13, as shown in FIG. 2, it is possible to control the capacity by 1 horsepower. Reference numeral 15 denotes a sensor (detection means) provided in the combined discharge pipe 16 of the two compressors 5 and 6, and the sensor 15 detects the temperature of the combined refrigerant discharged from the two compressors 5 and 6. The signal from this sensor 15 is input to the controller 17, and based on this signal, the first control means 18 for controlling the capacity of the compressors 5, 6 and the valve opening degree of the control valve 17 are controlled (largely). The second control means 19 is incorporated in the controller 17.

Next, the operation of this embodiment will be described.
In the refrigerant circuit of the air conditioner shown in FIG. 1, when the four-way valve 7 is switched to change the flow of refrigerant, cooling operation or heating operation is performed. In FIG. 1, the refrigerant flow during cooling is indicated by a solid line, and the refrigerant flow during heating is indicated by a broken line. By the way, during operation, the opening degree of the control valve 4 of each indoor unit A1, A2 is adjusted or the compressors 5, 6 are operated according to the load detected and calculated by a temperature sensor (not shown) of each indoor unit. The refrigerant is controlled by controlling the capacity of the above. Of course, the control valve 4 is closed in the indoor unit whose operation is stopped.

Next, the control method of this air conditioner will be described with reference to FIG. When the operation is started in step S ₁ , the air conditioner obtains the loads of the indoor units A1 and A2, obtains the capacities of the compressors 5 and 6 based on the total (required) horsepower, and as shown in FIG. Take control.
Further, in each of the indoor units A1 and A2, the valve opening degree of the control valve 4 is set according to the load of each of the indoor units A1 and A2, and the normal operation S ₂ is performed. Here, basically,
First, the control by the control valve 4 is first performed according to the air conditioning load, and then the capacity control of the compressors 5 and 6 described above is performed to perform smooth control according to the air conditioning load.

During the normal operation, the load applied to the compressors 5, 6 changes according to the change in the air conditioning load, and the temperature of the refrigerant discharged from the compressors 5, 6 changes. This change (temperature T _H ) is detected by the sensor 15 (step S ₃ ). If the temperature is less than a predetermined value, and therefore the motor windings of the compressor 5 and 6 (not shown) there is no risk of burning out, step S ₂ from Step S ₄
Return to

On the other hand, if the temperature is equal to or higher than a predetermined value, the windings of the electric motors of the compressors 5 and 6 may be burnt. Therefore, the following steps are taken to prevent this. That is, in step S ₅ , the operating indoor unit is detected,
The valve opening degree of the control valve 4 of the operating indoor unit is made larger than the current valve opening degree. As a result, the amount of refrigerant returning to the compressors 5, 6 increases, and it is considered that the temperature of the refrigerant discharged from the compressors 5, 6 decreases due to this increase. Then, in step S ₇ , the compressor 5,
If the discharge temperature of 6 is detected and the temperature is below the predetermined value, the process returns to step S ₂ , but if the temperature is above the predetermined value, the process proceeds to step S ₈ .

This step S ₈ lowers the capacity of the compressors 5, 6 per se compared to the present capacity, and it is considered that the temperature of the refrigerant discharged from the compressors 5, 6 inevitably decreases accordingly. Then detecting the discharge temperature of the compressor at step S ₉ again, if I the temperature is equal to or less than a predetermined value, but returns to the step S _2, if the above predetermined value has been continued longer control of Then, it is judged that there is a cause (for example, gas shortage) that cannot be dealt with, and operation is stopped.

As described above, according to the first aspect of the invention, in the multi-type air conditioner 1 in which the so-called expansion valve (control valve) is not provided in the outdoor unit B, the refrigerant temperature discharged from the compressors 5 and 6 is abnormally high ( When the temperature exceeds the set value), the valve opening of the control valve 4 of the indoor units A1 and A2 in operation is increased to suppress the rise in the temperature of the refrigerant discharged from the compressors 5 and 6, thereby reducing the temperature of the compressors 5 and 6 (motors). It is intended to protect the winding).

Further, in this embodiment, the pipe diameter of the indoor heat exchanger is 7 mm, which is set smaller than the pipe diameter 9 mm of the outdoor heat exchanger. The control valve 17 acting as a decompressor of the refrigerant is arranged only in the indoor units A1 and A2 so that the refrigerant flowing in the inter-unit pipe is in a liquid state during both cooling and heating operations. With these two configurations, the amount of the refrigerant filled in the refrigerant circuit can be minimized, and the receiver tank or the like is unnecessary.

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the gist of the present invention. For example, as shown in FIG. 4, one compressor 40 may be capable of changing its capacity with a power supply from the frequency conversion device 41. Further, as shown in FIG. 4, the valve opening degree of the control valve 4 of the indoor unit may be set in consideration of the length L of the inter-unit pipe 42 connecting the indoor unit A1 and the outdoor unit B. In this case, the temperature sensor 44 is provided in the suction pipe 43 of the compressor 40, and the test operation mode S ₅₀ as shown in FIG. 5 is performed prior to the normal operation S ₂ .
That is, the operation of the compressor 40 is started with the valve opening degree of the control valve 4 of each indoor unit maintained at a predetermined value.
When the temperature sensor 44 causes the suction pipe 43 to reach a predetermined temperature, it is determined that the refrigerant discharged from the compressor 40 has returned to the compressor 40, and the time required to reach the predetermined temperature is obtained to determine the length of the inter-unit pipe L. To estimate. Based on this estimation, the compressor 40 described above
Set the valve opening when the discharge temperature rises abnormally. That is, when the length L of the inter-unit pipe 42 is long, the valve opening is set to be larger than that when the length L is short. As a result, the amount of the refrigerant that returns from the indoor units A1 and A2 to the outdoor unit B per unit time increases, and the temperature of the refrigerant discharged from the compressor 40 can be promptly lowered.

Further, in this embodiment, the length L of the inter-unit pipe 42 is estimated by measuring the time until the refrigerant discharged from the compressor returns to the compressor again during the trial run. This unit piping 42
It goes without saying that the length L of the indoor units A1 and A2 may be set directly according to the calculated value. Further, it goes without saying that the present invention can be applied not only to a heat pump type air conditioner but also to a general refrigeration system.

[0024]

As described above, according to the first aspect of the invention, the outdoor unit having the compressor and the outdoor heat exchanger incorporated therein is provided with the plurality of units each having the expansion valve and the indoor heat exchanger incorporated therein. The indoor units are connected by pipes between the units, and when the temperature of the refrigerant discharged from the compressor reaches or exceeds a predetermined value, the valve opening of the expansion valve of the indoor unit is increased, so the refrigerant discharged from the compressor It is possible to protect the compressor by preventing an abnormal rise in temperature and reducing the risk of the winding inside the compressor being burnt out.

According to the second aspect of the invention, when the temperature of the refrigerant discharged from the variable capacity compressor exceeds a predetermined value, the valve opening degree of the expansion valve of the indoor unit is set rather than the capacity control of this compressor. Since the increasing control is preferentially performed, the compressor can be reliably protected even if a variable capacity compressor in which the temperature of the discharged refrigerant of the refrigerant easily changes.

According to the third invention, when the refrigerant discharge temperature of the compressor exceeds a predetermined value, the opening degree of the expansion valve of the indoor unit is increased according to the length of the inter-unit pipe. Therefore, even if the length of the inter-unit pipe becomes long, the compressor can be reliably protected.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigerating apparatus (air conditioner) of the present invention.

2 is an explanatory diagram of capacity control of the compressor and the like shown in FIG.

FIG. 3 is a flowchart showing control of the refrigerating apparatus shown in FIG.

FIG. 4 is a refrigerant circuit diagram of a refrigerating apparatus showing an embodiment different from FIG.

5 is a flowchart of a main part of control of the refrigerating apparatus shown in FIG.

[Explanation of symbols]

 3 Indoor heat exchanger 4 Control valve (expansion valve) 5, 6, 40 Compressor (compressor) 8 Outdoor heat exchanger 17 Controller 18 First control means 19 Second control means 42 Unit piping A1, A2 Indoor Unit B Outdoor unit

Claims (3)

[Claims] 1. A separation type refrigerating apparatus in which a plurality of indoor units having an expansion valve and an indoor heat exchanger are connected to an outdoor unit having a compressor and an outdoor heat exchanger incorporated therein. A refrigerating apparatus comprising a controller for increasing the opening degree of the expansion valve of the indoor unit when the temperature of the refrigerant discharged from the machine exceeds a predetermined value. 2. A separate type refrigeration system in which a plurality of indoor units having an expansion valve and an indoor heat exchanger are connected to an outdoor unit having a variable capacity compressor and an indoor heat exchanger incorporated therein. In the above, the detection means for detecting the temperature of the refrigerant discharged from the variable capacity compressor, the first control means for controlling the capacity of the variable capacity compressor, and the valve opening degree of the expansion valve A second control means for increasing the temperature, and when the value detected by the detection means exceeds a predetermined value, the second control means is preferentially operated over the first control means. . 3. A separate type refrigeration system in which a plurality of indoor units, each having an expansion valve and an indoor heat exchanger, are connected to an outdoor unit, which has a compressor and an outdoor heat exchanger, by connecting pipes between the units. In, when the temperature of the refrigerant discharged from the compressor is equal to or higher than a predetermined value, a controller that increases the valve opening degree of the expansion valve of the indoor unit according to the length of the inter-unit pipe is provided. Characterizing refrigeration equipment.