JP3305123B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner capable of cooling, heating, etc., and more particularly to an air conditioner for increasing or decreasing the number of revolutions of an electric compressor in accordance with a heat load or the like. It is.

[0002]

2. Description of the Related Art An air conditioner of this type is provided with a heat pump type refrigerant circuit having an electric compressor and rotation speed control means for controlling the rotation speed of the compressor. The operation such as cooling or heating is performed by increasing or decreasing the rotation speed of the compressor in accordance with the heat load or the like calculated based on the above. Further, during the operation of the compressor, the high pressure side (discharge side) pressure and the low pressure side (suction side) pressure are respectively detected, and based on each pressure, an overload, a shortage of refrigerant amount, and the like are monitored.

[0003]

In the above-mentioned conventional apparatus,
When the high-pressure side pressure exceeds a predetermined upper limit during compressor operation, the compressor is stopped to prevent overload, but every time the compressor is stopped, the air conditioning itself is also interrupted and the car is stopped. There is a problem that the indoor environment changes greatly.

On the other hand, when the low-pressure side pressure falls below a predetermined lower limit, the compressor is similarly stopped to prevent a failure of the compressor due to a shortage of the refrigerant amount. It is not properly determined whether or not it is necessary to perform the operation, and the compressor is stopped carelessly, causing the same problem as described above.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide an air conditioner capable of properly avoiding an overload due to an abnormality in the high pressure side pressure.
An object of the present invention is to provide an air conditioner capable of accurately protecting a compressor against abnormalities in the low pressure side pressure.

[0006]

In order to achieve the above object, the present invention is directed to an air conditioner for increasing or decreasing the number of revolutions of an electric compressor according to a heat load or the like. Means for inhibiting the increase in the number of revolutions when the high-pressure side pressure exceeds a predetermined upper limit value and gradually reducing the number of revolutions of the compressor; and Or a rotation speed reduction stop means for stopping the reduction of the rotation speed when the rotation speed becomes equal to or lower than a predetermined minimum rotation speed, and a high pressure side pressure lower than a predetermined value lower than the upper limit value in the rotation speed reduction stop process. comprising the increase correction permission means for permitting the rotation speed of the increasing correction when it is, the upper limit value
Based on the current low pressure as at least one of
It is characterized by using a value determined at time .

[0007]

According to a second aspect of the present invention, in an air conditioner for increasing or decreasing the number of revolutions of an electric compressor in accordance with a heat load or the like, the high pressure side pressure already exceeds a predetermined upper limit value when the compressor is started. A start restricting means for prohibiting the start of the compressor at some times and permitting the start of the compressor when the high pressure side pressure is equal to or lower than the upper limit is provided.

According to a third aspect of the present invention, in an air conditioner for increasing or decreasing the number of revolutions of an electric compressor in accordance with a heat load or the like, the low-pressure side pressure keeps a predetermined lower limit for a predetermined time during operation of the compressor. A rotation speed reduction means for inhibiting the rotation speed increase correction when the rotation speed falls below the predetermined value, and gradually reducing the rotation speed of the compressor; Rotation speed reduction stop means for stopping the reduction of the rotation speed when the rotation speed becomes lower than the minimum rotation speed, and when the low pressure side pressure becomes equal to or higher than a predetermined value higher than the lower limit value in the rotation speed reduction stop process, the rotation speed is reduced. An increase correction permitting means for permitting an increase correction is provided.

According to a fourth aspect of the present invention, in the air conditioner according to the third aspect, a value determined as needed based on the current outside air temperature is used as at least one of the lower limit values.

According to a fifth aspect of the present invention, in an air conditioner for increasing or decreasing the number of revolutions of an electric compressor in accordance with a heat load or the like, the low-pressure side pressure keeps a predetermined lower limit value for a predetermined time during operation of the compressor. The rotation speed reduction means for prohibiting the increase in the rotation speed when the rotation speed falls below the threshold value and gradually reducing the rotation speed of the compressor, and the same as when the rotation speed falls below a predetermined minimum rotation speed in the rotation speed reduction process. A rotating speed holding unit for holding the rotating speed for a predetermined time; and a refrigerant shortage determining unit for determining that the amount of the refrigerant is insufficient when the low pressure side pressure falls below a predetermined lower limit after the lapse of the time. And

According to a sixth aspect of the present invention, in the air conditioner according to the fifth aspect, the compressor is stopped when it is determined that the amount of refrigerant is insufficient, and the compressor is prohibited from starting until the air conditioner is restarted. A compressor stopping means is provided.

According to a seventh aspect of the present invention, in the air conditioner according to the fifth or sixth aspect, the count value for judging the shortage of the refrigerant amount and the count value for starting the compressor are compared, and when both reach a predetermined ratio. It is characterized by including a start prohibiting means for prohibiting all subsequent compressor starts.

[0014]

According to the first aspect of the present invention, when the high-pressure side pressure exceeds a predetermined upper limit during the operation of the compressor, the rotational speed increase correction is prohibited, and the rotational speed of the compressor is gradually reduced. Also, the current
The value determined at any time based on the low pressure side pressure is
As one of them, the abnormality determination of the high pressure side pressure is performed. If the high-pressure side pressure becomes equal to or less than the upper limit value or the number of rotations becomes equal to or less than the predetermined minimum number of rotations in the rotation number reduction process, the rotation number reduction is stopped. Then, when the high-pressure side pressure becomes equal to or lower than a predetermined value lower than the upper limit value in the rotation speed reduction stop process, the increase correction of the rotation speed is permitted.

[0015]

According to the second aspect of the present invention, when the high-pressure side pressure already exceeds a predetermined upper limit at the time of starting the compressor, the start-up of the compressor is prohibited. The machine is allowed to start.

According to the third aspect of the present invention, when the low pressure side pressure continuously falls below the predetermined lower limit for a predetermined time during the operation of the compressor, the rotation speed increase correction is prohibited, and the rotation speed of the compressor is gradually reduced. . If the low pressure side pressure becomes equal to or higher than the lower limit value or the rotation speed becomes equal to or lower than the predetermined minimum rotation speed in the rotation speed reduction process, the rotation speed reduction is stopped. When the low-pressure side pressure becomes equal to or higher than a predetermined value higher than the lower limit value in the rotation speed reduction stop process, the increase correction of the rotation speed is permitted.

According to the fourth aspect of the present invention, the abnormality on the low pressure side pressure is determined by setting a value determined as needed based on the current outside air temperature as one of the lower limit values. Other functions are the same as those of the third aspect .

According to the fifth aspect of the present invention, if the low pressure side pressure continuously falls below the predetermined lower limit for a predetermined time during the operation of the compressor, the rotation speed increase correction is prohibited, and the rotation speed of the compressor is gradually reduced. . In the process of reducing the number of revolutions, when the number of revolutions falls below a predetermined minimum number of revolutions, the same number of revolutions is maintained for a predetermined time. Then, if the low pressure side pressure falls below a predetermined lower limit value after a lapse of time, it is determined that the refrigerant amount is insufficient.

According to the sixth aspect of the present invention, when it is determined that the refrigerant amount is insufficient, the compressor is stopped, and the start of the compressor is prohibited until the air conditioner is restarted. Other functions are the same as those of the fifth aspect .

According to the seventh aspect of the present invention, the count value for judging the shortage of the refrigerant amount and the count value for starting the compressor are compared, and when both reach a predetermined ratio, all subsequent starting of the compressor is prohibited. Other operations are the same as those of the fifth or sixth aspect .

[0022]

1 and 2 show an example in which the present invention is applied to a vehicle air conditioner. FIG. 1 shows a refrigerant circuit, and FIG.
Shows a control circuit.

In FIG. 1, reference numeral 1 denotes a variable capacity type electric compressor, 2 denotes an outdoor heat exchanger, 3 denotes a first indoor heat exchanger, 4 denotes a second indoor heat exchanger, and 5 and 6 denote heat-sensitive second heat exchangers. 1, a second expansion valve,
7 to 10 are first to fourth solenoid valves, and 11 and 12 are first and second solenoid valves.
A check valve, 13 is a liquid receiver, and 14 is an accumulator.

Reference numeral 15 denotes a duct for air conditioning in the vehicle interior, 16 denotes an outside air inlet, 17 denotes an inside air inlet, 18 denotes a switching damper for the inlet, 19 denotes a vent outlet, 20 denotes a foot outlet, and 21 denotes a differential outlet. , 22 are opening / closing dampers for vent outlets, 23
Is an opening / closing damper for a foot outlet, 24 is an opening / closing damper for a differential outlet, 25 is an air mix damper, and 26 is an electric fan.

The discharge port of the compressor 1 is connected to one end of the outdoor heat exchanger 2 via a fourth solenoid valve 10, and the other end of the outdoor heat exchanger 2 is received via a first check valve 11. It is connected to the inlet of the liquid container 13. The outlet of the liquid receiver 13 is connected to one end of the first indoor heat exchanger 3 via the third solenoid valve 9 and the first expansion valve 5, and the other end of the first indoor heat exchanger 3 is connected to the accumulator 14. The outlet of the accumulator 14 is connected to the inlet of the compressor 1.

The discharge port of the compressor 1 is connected to one end of the second indoor heat exchanger 4 via the first solenoid valve 7,
The other end of the indoor heat exchanger 4 is connected to the inlet of the liquid receiver 13 via the second check valve 12. Further, a second expansion valve 6 is interposed between the outlet of the liquid receiver 13 and the other end of the outdoor heat exchanger 2, and one end of the outdoor heat exchanger 2 and the accumulator 1
A second solenoid valve 8 is interposed between the second solenoid valve 8 and the inlet 4.

In FIG. 2, 27 is an air conditioner switch,
28 is an air-conditioning temperature setting device, 29 is a ventilation mode setting device, 30
Is an inside air temperature detector composed of a thermistor, etc., 31 is a similar outside air temperature detector, 32 is a solar radiation amount detector composed of a photo sensor, etc., and 33 is a pressure detector which detects the pressure on the high pressure side (discharge side) of the compressor 1. , 34 are pressure detectors for detecting the pressure on the low pressure side (suction side) of the compressor 1, 35 is a microcomputer, 36 is a compressor drive circuit, 37 is a solenoid valve drive circuit, and 38 is a fan drive circuit.

The air-conditioning temperature setting device 28 has a temperature setting lever or a temperature setting button and the like, and a desired air-conditioning temperature can be appropriately selected and set by these operations. The blower mode setting device 29 is provided with an air volume variable lever capable of designating OFF and AUTO, and the air volume can be changed in multiple stages by the variable lever, and the air volume can be switched to microcomputer control by an AUTO switch.

The microcomputer 35 includes a CPU, a ROM, a RAM, and the like, and performs programs for operating mode determination, compressor rotation control, valve switching control, and the like, as well as pressure limiting control and abnormality limiting control of the compressor 1 which will be described in detail later. The program is stored in the ROM. The microcomputer 35 is provided with the air conditioner switch 2
7, operation signals of the air-conditioning temperature setter 28 and the blower mode setter 29, and the inside air temperature detector 30, the outside air temperature detector 31,
Solar radiation detector 32 and two pressure detectors 3 on the high and low pressure side
A predetermined signal is sent to each of the driving circuits 36, 37, and 38 based on the detection signals of the third and third detection circuits.

The compressor drive circuit 36 controls the number of revolutions of the compressor 1 based on the number of revolutions signal (hereinafter, referred to as a DUTY signal) from the microcomputer 35 to vary the discharge capacity. The solenoid valve drive circuit 37 controls the opening and closing of each of the solenoid valves 7 to 10 based on the mode signal from the microcomputer 35 to switch the refrigerant cycle. The fan drive circuit 38 controls the power supplied to the electric fan 26 based on the air volume signal from the microcomputer 35 to vary the air blowing capacity.

The above-described air conditioner includes first to fourth solenoid valves 7
The operation in one of the cooling, cooling and drying, heating and heating and drying modes is enabled by switching the refrigerant cycle by 10 to 10, and each operation mode includes a set temperature, a detected value of an inside air temperature, an outside air temperature, and a detected value of solar radiation. Is automatically determined and activated by the microcomputer 35 based on the

In the cooling mode operation, the compressor 1 and the electric motor are operated with the first and second solenoid valves 7, 8 closed and the third and fourth solenoid valves 9, 10 open as shown in FIG. Fan 26
It is executed by operating. The refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 2 through the fourth solenoid valve 10 and is condensed. The first expansion valve 5 and the second expansion valve 5 pass through the first check valve 11, the liquid receiver 13 and the third solenoid valve 9. It flows into one indoor heat exchanger 3, evaporates, and is sucked into the compressor 1 through the accumulator 14. That is, in the same operation mode, the first
The interior of the vehicle can be cooled using the heat absorption effect exerted by the indoor heat exchanger 3.

As shown in FIG. 3, the compressor 1 and the compressor 1 and the fourth solenoid valve 7 are opened while the second solenoid valve 8 is closed. This is executed by operating the electric fan 26. A part of the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 2 through the fourth solenoid valve 10 and is condensed, and then flows through the first check valve 11, the liquid receiver 13 and the third solenoid valve 9 into the first expansion valve 5. And the first
After flowing into the indoor heat exchanger 3 and evaporating, the accumulator 1
The refrigerant is sucked into the compressor 1 through 4. Further, the remaining portion of the refrigerant flows into the second indoor heat exchanger 4 through the first solenoid valve 7 and is condensed. After passing through the second check valve 12, the refrigerant merges with the above-described refrigerant. That is, in the same operation mode, the first indoor heat exchanger 3 and the second indoor heat exchanger 4 exhibit heat absorbing and radiating functions, respectively, and use both functions to lower the air outlet temperature without reducing the air outlet temperature. It is possible to dehumidify,
The temperature and the amount of dehumidification at this time can be controlled by adjusting the discharge capacity of the compressor 1 and adjusting the opening of the air mix damper 25. Further, the outdoor heat exchanger 2 emits surplus heat under the condition that the degree of opening of the air mix damper 25 is close to zero (the amount of air passing through the second indoor heat exchanger 4 is zero), and the balance between heat absorption and heat radiation is properly adjusted. To keep.

As shown in FIG. 3, the operation in the heating mode is performed with the first and second solenoid valves 7, 8, and 9 opened and the fourth solenoid valve 10 closed, and the compressor 1 and the electric motor are operated. This is executed by operating the fan 26. The refrigerant discharged from the compressor 1 flows into the second indoor heat exchanger 4 through the first solenoid valve 7 and is condensed. After passing through the second check valve 12 and the liquid receiver 13, the refrigerant is divided, and a part of the refrigerant is removed from the refrigerant. It flows into the first expansion valve 5 and the first indoor heat exchanger 3 through the three solenoid valves 9, evaporates, and is sucked into the compressor 1 through the accumulator 14. The remaining part of the refrigerant flows into the second expansion valve 6 and the outdoor heat exchanger 2 and evaporates. After passing through the second solenoid valve 8, the refrigerant merges with the refrigerant at the inlet of the accumulator 14. That is, in the same operation mode, the second indoor heat exchanger 4
The interior of the vehicle can be heated by utilizing the heat radiation effect exerted by the first heat exchanger, and the heat absorption effect of the first indoor heat exchanger 3 is utilized by exerting the heat absorption effect in the outdoor heat exchanger 2 and the first indoor heat exchanger 3. It is possible to simultaneously perform dehumidification in the vehicle compartment, and the heating capacity and the dehumidification amount at this time can be controlled by adjusting the discharge capacity of the compressor 1 and the opening degree of the air mix damper 25.

As shown in FIG. 3, the operation in the heating dry mode is performed by opening the first and third solenoid valves 7 and 9 and closing the second and fourth solenoid valves 8 and 10 while the compressor 1 and the compressor 1 are closed. This is executed by operating the electric fan 26. The refrigerant discharged from the compressor 1 flows into the second indoor heat exchanger 4 through the first solenoid valve 7 and is condensed, and the second check valve 12 and the liquid receiver 13
Then, it flows into the first expansion valve 5 and the first indoor heat exchanger 3 through the third solenoid valve 9, evaporates, and is sucked into the compressor 1 through the accumulator 14. That is, in the same operation mode, the interior of the passenger compartment can be heated using the heat radiation effect exerted in the second indoor heat exchanger 4 and the vehicle can be heated using the heat absorption effect exerted in the first indoor heat exchanger 3. It is possible to simultaneously perform indoor dehumidification, and the heating capacity and the dehumidification amount at this time can be controlled by adjusting the discharge capacity of the compressor 1 and the opening degree of the air mix damper 25.

FIG. 4 shows the procedure of the pressure limiting control and the abnormal limiting control of the compressor 1 performed in each of the above operation modes.
This will be described in detail with reference to the flowcharts of FIGS.

FIG. 4 shows a control procedure of the maximum pressure limitation performed during the operation of the compressor. First, when the compressor 1 is operating and the rotational speed increase correction for the compressor 1 is not prohibited (steps ST1 and ST2), the condition of Pd>A.Pd> MPd is monitored (step ST3). 4). P in the condition
d is the current high pressure side pressure, A is a preset pressure constant, M
Pd is the high pressure side target maximum pressure. The target high pressure MPd on the high pressure side is expressed as MPd = ab × Ps (a, b: constant, Pd
s: current low-pressure side pressure), that is, as needed, based on the current low-pressure side pressure Ps.

When the current high-pressure side pressure Pd exceeds both the pressure constant A and the high-side target maximum pressure MPd, the rotational speed increase correction of the compressor 1 by temperature control or the like is prohibited and the compressor drive circuit 36 The value of the output DUTY signal is reduced at a predetermined rate to gradually reduce the rotation speed of the compressor 1 (steps ST5 and ST9).

After the start of the rotation speed reduction, the following conditions are monitored: Pd ≦ MPd Pd ≦ A DUTY value> B (steps ST6 to ST8, ST14). The DUTY value in the condition is a value of the DUTY signal, and B is a signal value representing a preset minimum rotation speed.

By reducing the rotation speed, the current high-pressure side pressure Pd
When the pressure becomes equal to or lower than the high-pressure-side target maximum pressure MPd or the pressure constant A, or when the DUTY value becomes equal to or lower than the signal value B of the minimum rotation speed, the rotation speed reduction is stopped (step ST10).

[0041] After stopping the rotation speed reduction, subsequently, to monitor the condition of · Pd ≦ MPd-C · P d ≦ D ( step ST11,12). C in the condition is a preset pressure correction number, and D is a pressure constant smaller than A above.

When the current high pressure side pressure Pd becomes lower than the high pressure side target maximum pressure MPd or becomes lower than the pressure constant D due to the rotation speed reduction stop, the prohibition of the rotation speed increase correction previously executed is released. Then, the process goes out of the series of limit control and shifts to the normal compressor speed control (step ST13).

FIG. 5 shows a control procedure of the high-pressure abnormality restriction performed at the time of starting the compressor. First, when the compressor 1 is started, the condition of: Pd ≦ A is monitored (steps ST1 and ST2).

When the high-pressure side pressure Pd is equal to or less than the pressure constant A when the compressor is started, the start is permitted (step ST3),
On the other hand, when the high-pressure side pressure Pd has already exceeded the pressure constant A, its activation is prohibited (step ST4). Incidentally, the start prohibition in step ST4 is released when the control circuit is turned on again.

FIG. 6 shows a control procedure of the minimum pressure limitation performed during the operation of the compressor. First, when the compressor 1 is operating and the rotational speed increase correction for the compressor 1 is not prohibited (steps ST1 and ST2), the condition that Ps <SPs is continued for the time E is monitored (step ST1). ST3, 4). S in the condition
Ps is a low-pressure-side target maximum pressure and E is a preset time constant. SPs = c + d × Tam (c, d: constant, Ta under the condition of Tam <Ts)
m: outside air temperature, Ts: set temperature in low temperature range)
Under the condition of am ≧ Ts, it is determined at any time by the formula of SPs = c, that is, based on the current outside air temperature Tm.

When the current low-pressure side pressure Ps continuously falls below the low-pressure target minimum pressure SPs for the time E, the increase in the rotational speed of the compressor 1 by temperature control or the like is prohibited, and the compressor drive circuit 36 , The value of the DUTY signal output is reduced at a predetermined rate to gradually reduce the rotation speed of the compressor 1 (steps ST5 and ST8).

After the start of the rotation speed reduction, the following conditions are monitored: Ps ≧ SPs DUTY value> B (steps ST6, ST12).

By reducing the rotational speed, the current low pressure side pressure Ps
Is lower than the low-pressure-side target minimum pressure SPs, or when the DUTY value has become equal to or lower than the minimum rotation speed signal value B (step ST9).

After the rotation speed reduction is stopped, the condition of: Ps ≧ SPs + F is monitored (step ST10). F in the condition is a preset pressure correction number.

When the current low pressure side pressure Ps becomes higher than the low pressure side target minimum pressure SPs or more due to the rotation speed reduction stop, the prohibition of the rotation speed increase correction previously executed is released (step ST11). Then, the routine shifts from the limit control to the normal compressor speed control.

FIG. 7 shows a control procedure of the abnormal low pressure limit performed during the minimum pressure limit control. First, when the minimum pressure limit control is being performed (step ST1)
Monitors the condition of DUTY value> B (step ST2).

During the execution of the minimum pressure limit control, the duty
When the value becomes equal to or less than the signal value B of the minimum rotation speed, the same value is held for a predetermined time G (step ST3).

After the DUTY value is held, the condition of: Ps ≧ SPs is monitored (step ST4).

When the current low pressure side pressure Ps falls below the low pressure side target minimum pressure SPs by holding the DUTY value,
Assuming that the refrigerant amount is insufficient, the value of the DUTY signal is set to zero, the compressor 1 is stopped, and this is stored in the memory as the number of stop times 1, and the power supply to the control circuit is repeated until the air conditioner is restarted. Until the start of the compressor 1 is prohibited (steps ST5 to ST7).

The above-described determination of the shortage of the refrigerant amount is stored and counted each time, and when the ratio of the count value to the count value of starting the compressor reaches a predetermined% value, the starting of the compressor thereafter is all prohibited.
By the way, the starting of the compressor here does not include the temperature control or the like during the operation, and only the first starting of the compressor after the power is supplied to the control circuit is counted.

As described above, according to the present embodiment, even if an abnormality occurs in the high-pressure side pressure Pd during the operation of the compressor, the compressor 1 is not stopped immediately as in the prior art, but by reducing the rotation speed of the compressor 1. There is an advantage that overload due to abnormal pressure can be accurately avoided.

Further, a value determined as needed based on the low-pressure side pressure Ps (high-pressure target maximum pressure MPd), that is, a value corrected according to the fluctuation of the low-pressure side pressure Ps, is set as one of the upper limit values. By performing the Pd abnormality determination, there is an advantage that the abnormality determination can be accurately performed by properly grasping the load of the compressor 1 from the state of the intake gas, which is difficult to determine only by the value on the high pressure side.

When the compressor is started, the high-pressure side pressure Pd
There is an advantage that it is possible to surely prevent the compressor 1 from being started carelessly when an abnormality has occurred.

Further, even if an abnormality occurs in the low pressure side pressure Ps during the operation of the compressor, whether the pressure is really abnormal by reducing the rotation speed of the compressor 1 without immediately stopping the compressor as in the related art. And the compressor can be properly protected against abnormalities.

Further, a value (low-pressure-side target minimum pressure SPs) determined as needed based on the outside air temperature Tam, that is, a value corrected according to the fluctuation of the outside air temperature Tam, is set as one of the lower limit values, and the low-pressure side pressure Ps is determined. By performing the abnormality determination, there is an advantage that the abnormality determination can be accurately performed by appropriately grasping the low pressure side pressure Ps, which has a low absolute value of the pressure and is easily affected by the outside air temperature Tam, in consideration of the temperature influence.

Further, the shortage of the refrigerant amount is clearly distinguished from the decrease of the low-pressure side pressure, so that it is possible to accurately determine the refrigerant amount shortage, and when the refrigerant amount shortage is determined, the compressor 1 is immediately stopped. Thus, there is an advantage that failure of the compressor 1 or malfunction of the refrigerant circuit due to the shortage of the refrigerant amount can be reliably prevented.

Further, the above-mentioned count value for judging the shortage of the refrigerant amount and the count value for starting the compressor are compared, and when both of them reach a predetermined ratio, all subsequent starting of the compressor is prohibited. There is an advantage that it is possible to prevent the compressor from being erroneously started in a state where the amount is insufficient, suppress damage caused by insufficient refrigerant amount, and improve reliability.

Although the present invention has been described with reference to an example in which the present invention is applied to an air conditioner for a vehicle, any air conditioner using a compressor whose capacity can be adjusted by increasing or decreasing the number of revolutions is not limited to a vehicle, but is used for a house. It can be widely applied to an air conditioner and the like, and the same effect can be obtained.

[0064]

As described above in detail, according to the first aspect of the present invention, even if an abnormality occurs in the high-pressure side pressure during the operation of the compressor, the compressor can be stopped without immediately stopping the compressor as in the prior art. By reducing the number of revolutions of the machine, overload due to the abnormal pressure can be properly avoided. Also, based on low pressure side pressure
Depending on the value determined from time to time, that is, the fluctuation of the low pressure side pressure.
The value to be corrected is regarded as one of the upper limit values,
Pressure, it is difficult to judge from the high pressure side value alone.
Determine the abnormality by properly grasping the load of the compressor from the state of the intake gas
Can be accurately implemented.

[0065]

[0066]

According to the second aspect of the present invention, it is possible to reliably prevent the compressor from being started carelessly if the high-pressure side pressure is already abnormal when the compressor is started.

According to the third aspect of the present invention, even if an abnormality occurs in the low-pressure side pressure during the operation of the compressor, the pressure is reduced by reducing the rotation speed of the compressor without immediately stopping the compressor as in the conventional case. It is possible to appropriately determine whether or not the compressor is really abnormal and to appropriately protect the compressor against the abnormality.

According to the fourth aspect of the present invention, a value determined as needed based on the outside air temperature, that is, a value corrected in accordance with a change in the outside air temperature, is set as one of the lower limit values, and the low pressure side pressure abnormality is determined. Accordingly, the abnormality determination can be accurately performed by appropriately grasping the low pressure side pressure which has a low absolute value of the pressure and is easily affected by the outside air temperature in consideration of the temperature influence. Other effects are the same as those of the third aspect .

According to the fifth aspect of the invention, the shortage of the refrigerant amount can be clearly distinguished from the lowering of the low pressure side pressure, and the refrigerant amount shortage can be accurately determined.

According to the sixth aspect of the present invention, when it is determined that the refrigerant amount is insufficient, the compressor is immediately stopped, and the failure of the compressor or the malfunction of the refrigerant circuit caused by the insufficient refrigerant amount is reliably performed. Can be prevented. Other effects are the same as those of the fifth aspect .

According to the seventh aspect of the present invention, the count value for judging the shortage of the refrigerant amount and the count value for starting the compressor are compared, and when both reach a predetermined ratio, all subsequent starts of the compressor are performed. By prohibiting, it is possible to prevent the compressor from being erroneously started in a state where the amount of the refrigerant is insufficient, to suppress the damage caused by the insufficient amount of the refrigerant, and to improve the reliability. Other effects are the same as those of the fifth or sixth aspect of the present invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing a refrigerant circuit of an air conditioner according to the present invention.

FIG. 2 is a diagram showing a control circuit of the air conditioner according to the present invention.

FIG. 3 is a diagram showing a solenoid valve switching state in each operation mode.

FIG. 4 is a flowchart of a maximum pressure limit control.

FIG. 5 is a flowchart of high-pressure abnormality limiting control.

FIG. 6 is a flowchart of a minimum pressure limiting control.

FIG. 7 is a flowchart of low pressure abnormality limit control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Outdoor heat exchanger, 3 ... First indoor heat exchanger, 4 ... Second indoor heat exchanger, 5 ... First expansion valve, 6 ... Second
Expansion valve, 35: microcomputer, 36: compressor drive circuit.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshihiko Fujita 20 Kotobukicho, Isesaki-shi, Gunma Sanden Co., Ltd. (56) References JP-A-7-257162 (JP, A) JP-A-7-103582 ( JP, A) JP-A-58-78074 (JP, A) JP-A-4-353013 (JP, A) JP-A-1-237216 (JP, A) JP-A-6-265225 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) B60H 1/32

Claims (7)

(57) [Claims] An air conditioner for increasing or decreasing the number of revolutions of an electric compressor according to a heat load or the like, wherein the number of revolutions is increased when the high-pressure side pressure exceeds a predetermined upper limit value during operation of the compressor. Rotation speed reducing means for gradually reducing the rotation speed of the compressor, and rotating when the high pressure side pressure is equal to or lower than the upper limit value or the rotation speed is equal to or lower than a predetermined minimum rotation speed in the rotation speed reduction process. Rotation speed reduction stop means for stopping the number reduction; and increase correction permission means for permitting increase correction of the rotation speed when the high pressure side pressure falls below a predetermined value lower than the upper limit value in the rotation speed reduction stop process. The current low pressure side pressure as at least one of the upper limit values
An air-conditioning apparatus characterized by using a value determined as needed based on the value . 2. An air conditioner for increasing / decreasing the number of revolutions of an electric compressor according to a heat load or the like, wherein when the high pressure side pressure already exceeds a predetermined upper limit value at the time of starting the compressor, the compressor is started. An air conditioner, comprising: start-up restricting means for prohibiting start-up and permitting start-up of the compressor when the high-pressure side pressure is equal to or lower than the upper limit. 3. An air conditioner for increasing or decreasing the number of revolutions of an electric compressor according to a heat load, etc., when the low pressure side pressure continuously falls below a predetermined lower limit for a predetermined time during operation of the compressor. Means for reducing the number of rotations of the compressor and gradually reducing the number of rotations of the compressor; and, in the step of reducing the number of rotations, the low-pressure side pressure is equal to or higher than the lower limit, or the number of rotations is equal to or lower than a predetermined minimum number of rotations. Rotation speed reduction stopping means for stopping the reduction of the rotation speed when the rotation speed becomes lower, and permitting the increase correction of the rotation speed when the low pressure side pressure becomes equal to or higher than a predetermined value higher than the lower limit value in the rotation speed reduction stop process. An air conditioner comprising: an increase correction permission unit. 4. The air conditioner according to claim 3 , wherein a value determined as needed based on the current outside air temperature is used as at least one of the lower limit values. 5. An air conditioner for increasing or decreasing the number of revolutions of an electric compressor according to a heat load, etc., when the low pressure side pressure continuously falls below a predetermined lower limit for a predetermined time during operation of the compressor. Means for reducing the number of rotations of the compressor and gradually reducing the number of rotations of the compressor; and, when the number of rotations falls below a predetermined minimum number of rotations during the rotation number reduction process, the same number of rotations is maintained for a predetermined time. Air conditioner, comprising: a rotation speed holding unit that holds only the rotation speed; and a refrigerant shortage determination unit that determines that the amount of refrigerant is insufficient when the low pressure side pressure falls below a predetermined lower limit after the lapse of the time. apparatus. 6. A compressor stopping means for stopping the compressor when it is determined that the amount of refrigerant is insufficient, and prohibiting the compressor from being started until the air conditioner is restarted. 6. The air conditioner according to 5 . 7. A compressor start inhibiting means for comparing a count value for judging a refrigerant shortage and a count value for starting a compressor, and when both reach a predetermined ratio, prohibit all subsequent start of the compressor. The air conditioner according to claim 5 or 6, wherein: