JP4131318B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner, and more particularly to an air conditioner that prevents overheating of a compressor or an inverter without performing overheat prevention control at the expense of normal air conditioning control.
[0002]
[Prior art]
Some vehicles are equipped with an air conditioner that maintains the temperature in the passenger compartment in an appropriate state. The air conditioner includes a compressor, a compressor motor that drives the compressor, and an evaporator that vaporizes the refrigerant compressed by the compressor.
[0003]
As an air conditioner, there is one disclosed in JP-A-8-40053. The electric compressor protecting method disclosed in this publication and the apparatus having the same are provided with a temperature sensor that continuously detects the temperature of the winding of the motor built in the electric compressor, and detects the high temperature state of the winding. A first setting for detecting, a second setting for detecting a higher temperature state than the first setting, and a third setting for detecting a low temperature state of the winding, wherein the winding temperature is set to the first setting. When it exceeds, the number of rotations of the electric compressor is limited. When the winding temperature exceeds the second setting or becomes lower than the third setting, the electric compressor is stopped. Prevents occupants from becoming uncomfortable due to large fluctuations in the air temperature, and at the same time ensuring that the electric compressor is protected from high temperature conditions with high accuracy and when the compressor is operated to a very low outside temperature by heat pump heating. , Compression due to liquid compression and poor lubrication function There has been prevented from being damaged.
[0004]
Further, there is one disclosed in Japanese Patent Laid-Open No. 2001-66002. The air conditioner disclosed in this publication is provided with a temperature detecting means for detecting either the temperature of the refrigerant discharged from the compressor or the temperature of the motor in an air conditioner including a compressor driven to rotate by a motor. The rate of change in temperature is obtained based on the temperature detected by the temperature detection means, the frequency of the alternating current supplied to the motor is corrected according to the rate of change, and air conditioning is performed more efficiently.
[0005]
[Problems to be solved by the invention]
By the way, when an electric inverter type air conditioner used as a room air conditioner is mounted on a vehicle, for example, an electric vehicle, the usage environment becomes more intense than the room air conditioner compressor, and the compressor often overheats even in the normal range. Need to be stopped.
[0006]
Once the compressor was stopped, the compressor was started after only about 2 to 3 minutes. However, in the case of the electric vehicle, there is little space to be air-conditioned, the influence of solar radiation, and cooling. In this case, since the occupant is in a comfortable state by directly applying the blowing wind to the occupant, the stop time has a large effect on the room temperature and the occupant's comfort, and the cabin temperature and the blowing temperature fluctuate greatly, There is an inconvenience that passengers become uncomfortable.
[0007]
Further, in the disclosed Japanese Patent Application Laid-Open No. H8-40053, a temperature sensor for continuously detecting the temperature of the winding of the motor built in the compressor (in other words, “electric compressor” in the publication) is provided, A first setting for detecting a high temperature state of the winding, a second setting for detecting a higher temperature state than the first setting, and a third setting for detecting a low temperature state of the winding. When the temperature exceeds the first setting, the rotational speed of the electric compressor is limited, and when the winding temperature exceeds the second setting or becomes lower than the third setting, the electric compressor is stopped. ing. The third setting is irrelevant to that of the present invention and will not be described.
[0008]
However, the above-mentioned Japanese Patent Laid-Open No. 8-40053 can reduce the frequency of stopping the compressor, but limits the rotation speed instead of stopping the compressor. It is not a solution to the inconvenience that the occupants are uncomfortable.
[0009]
[Means for Solving the Problems]
Accordingly, in order to eliminate the above-described disadvantages, the present invention detects the compressor temperature of the compressor in an air conditioner composed of at least a compressor driven by a motor and an evaporator that vaporizes refrigerant compressed by the compressor. And a compressor upper limit rotational speed is calculated based on a difference between a compressor temperature detected by the temperature detector and a target compressor temperature set in advance separately from a temperature determined to be in a high temperature state. At the same time, the target compressor speed is calculated so as to correspond to the arbitrarily set temperature, the compressor upper limit speed is compared with the target compressor speed, and if the compressor upper limit speed is lower, While the compressor upper limit speed is set as the target compressor speed, Presser when towards the upper limit engine speed is high, characterized in that a control means for controlling the compressor driving to prevent large becomes variation of the target compressor rotational speed is directly used passenger compartment temperature and the outlet temperature.
[0010]
Further, in an air conditioner composed at least of a compressor driven by an inverter-controlled motor and an evaporator for vaporizing refrigerant compressed by the compressor, a temperature detecting means for detecting the inverter temperature of the inverter is provided, and this temperature The compressor upper limit rotation speed is calculated based on the difference between the inverter temperature detected by the detection means and the target inverter temperature set in advance separately from the temperature determined to be in a high temperature state, and the set temperature set arbitrarily. The target compressor speed is calculated so that the compressor upper limit speed is compared with the target compressor speed. If the compressor upper speed is lower, the compressor upper speed is set to the target compressor speed. On the other hand, if the compressor upper limit speed is higher It is characterized in that a control means for controlling the compressor driving to prevent large become variations of the temperature and blowing directly used vehicle interior temperature target compressor speed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
As a result of the invention as described above, when the compressor upper limit rotational speed is lower, the control means controls the compressor drive with the compressor upper limit rotational speed as the target compressor rotational speed, and overheat prevention control sacrifices normal air conditioning control. This prevents the compressor from overheating and contributes to the improvement of product appeal.
[0012]
In addition, when the compressor upper limit rotational speed is lower, the control means controls the compressor drive with the compressor upper limit rotational speed as the target compressor rotational speed, and does not perform overheat prevention control at the expense of normal air conditioning control. This contributes to the improvement of product appeal.
[0013]
【Example】
Embodiments of the present invention will be described below in detail with reference to the drawings.
[0014]
1 to 3 show an embodiment of the present invention. In FIG. 3, 2 is a heat pump type air conditioner mounted on a vehicle (not shown).
[0015]
The air conditioner 2 includes at least a compressor 4, a compressor motor 6 that drives the compressor 4, and an evaporator 8 that vaporizes the refrigerant compressed by the compressor 4.
[0016]
That is, as shown in FIG. 3, the air conditioner 2 is provided with a condenser 12 connected to the compressor 4 via a first path 10-1, and a receiver 14 is connected to the capacitor 12 via a second path 10-2. Connected and provided, connected to the receiver 14 via the third path 10-3 and provided with the expansion valve 16, connected to the expansion valve 16 via the fourth path 10-4 and provided with the evaporator 8 The compressor 4 is connected to the evaporator 8 via a fifth path 10-5.
[0017]
A condenser fan 20 driven by a condenser motor 18 is provided in the vicinity of the condenser 12, and the compressor motor 6 is connected to the compressor 4.
[0018]
Further, a control means (also referred to as “A / C controller” or “air conditioner controller”) 22 of the air conditioner 2 is provided, and an inverter 24 is connected to the control means 22.
[0019]
The inverter 24 includes a compressor temperature sensor 26 that detects the compressor temperature of the compressor 4, a compressor motor current sensor 28 that detects the compressor motor current of the compressor motor 6, and an inverter temperature that detects the inverter temperature of the inverter 24. The inverter 24 is connected to the sensor 30, and the inverter 24 outputs detection signals such as the actual rotation speed, the compressor current, and each temperature to the control means 22, and inputs a start command and a rotation speed command from the control means 22. .
[0020]
Further, the control means 22 is provided in the middle of the first path 10-1 between the compressor 4 and the condenser 12, and includes a refrigerant pressure sensor 32 that detects a high-pressure side refrigerant pressure, and an evaporator that detects the evaporator temperature of the evaporator 8. The temperature sensor 34, the capacitor motor current sensor 36 for detecting the capacitor motor current of the capacitor motor 18, the outside air temperature sensor 38 for detecting the outside air temperature, and the temperature adjusting means 40 for inputting the temperature adjustment value are connected. Provide.
[0021]
The function of the control means 22 will be described with reference to FIG. 2. When the compressor temperature from the compressor temperature sensor 26 or the inverter temperature from the inverter temperature sensor 30 is input to the control means 22, the control means 22 ) Temperature stability control processing A is performed, and a compressor motor drive processing command B is output to the inverter 24, and a capacitor motor drive processing command C is output to the capacitor motor (also referred to as “DC motor”) 18.
[0022]
The inverter 24 to which the compressor motor drive processing command B is input outputs the compressor 24 to the compressor motor (also referred to as “sensorless brushless motor”) 6, and the compressor motor (also referred to as “sensorless brushless motor”) 6 serves as the compressor 4. , And the compressor temperature sensor 26 detects the compressor temperature of the compressor 4.
[0023]
In addition, the capacitor motor (also referred to as “DC motor”) 18 to which the capacitor motor drive processing instruction C is input drives the capacitor fan 20.
[0024]
Here, the outline of the present invention will be described. The air conditioner 2 compresses the air conditioning refrigerant and detects the temperature of the compressor motor 6 or the temperature of an inverter 24 described later (a compressor temperature sensor 26 or inverter described later). This is a protective measure when the compressor 4 incorporating the temperature sensor 30) and the inverter 24 are controlled at a variable rotational speed, and the rotational speed of the compressor motor 6 is controlled by the inverter 24 so that the motor temperature or the compressor temperature becomes a predetermined value. Control (for example, PID (proportional integral derivative) control).
[0025]
The control means 22 calculates the compressor upper limit rotation speed from the temperature detection means, for example, the compressor temperature detected by the compressor temperature sensor 26 and a preset target compressor temperature, and corresponds to an arbitrarily set temperature. If the compressor upper limit rotational speed is lower than the compressor upper limit rotational speed, the compressor upper limit rotational speed is set as the target compressor rotational speed. It has a drive control function.
[0026]
Further, when calculating the compressor upper limit rotation speed, the inverter temperature detected by the inverter temperature sensor 30 can be used instead of the compressor temperature detected by the compressor temperature sensor 26. However, in this embodiment, the compressor temperature will be described.
[0027]
Specifically, the control means 22 first determines whether or not the evaporator freeze prevention processing condition is satisfied. The evaporator freeze prevention processing condition is that the compressor 4 is stopped when the evaporator temperature becomes equal to or lower than the first predetermined value, and the compressor is stopped when the evaporator temperature becomes equal to or higher than the second predetermined value (> first predetermined value). 4 is driven.
[0028]
When the above-described evaporator freeze prevention processing condition is satisfied, the control means 22 detects the compressor temperature by the compressor temperature sensor 26, and calculates the compressor upper limit rotational speed from the deviation between the compressor temperature and the target compressor temperature. Then, the compressor (inverter) temperature stability control process A is performed.
[0029]
That is, the compressor upper limit rotation speed NCt can be calculated by the following equation.
NCt = Kp (TCm−TC) + KI∫ (TCm−TC) dt + NCm
Kp: coefficient TCm: target compressor temperature TC: compressor temperature KI: coefficient NCm: target compressor speed
At this time, the target compressor speed is calculated by calculating the compressor speed corresponding to the temperature adjustment value of the temperature adjusting means 40, and the target compressor temperature is higher than the temperature at which the compressor 4 is determined to be in a high temperature state. Also make the temperature low.
[0031]
According to the above formula, the compressor (inverter) temperature stabilization control process A compares the compressor upper limit rotational speed with the target compressor rotational speed when the target compressor rotational speed is higher than the calculated compressor upper limit rotational speed. When the upper limit rotational speed is lower, the target compressor rotational speed is limited.
[0032]
For reference, the control means 22 generates a rotating magnetic field in the armature winding of the compressor motor 6 when the compressor motor 6 is started, and performs forced operation control (open loop control) in response to the start command. Is running through.
[0033]
Further, at the time of restart, the frequency control process for controlling the frequency of the rotating magnetic field generated in the armature winding, the applied voltage control process for controlling the voltage applied between the armature windings, and the time for forced operation are controlled. Combined with operation time control processing.
[0034]
Further, the control means 22 drives the condenser fan 20 by directly applying or turning off 12 V to the condenser motor 18 consisting of a simple 12 VDC motor.
[0035]
Next, the operation will be described along the control flowchart of the air conditioner 2 of FIG.
[0036]
The flowchart for control of the air conditioner 2 in FIG. 1 shows the compressor (inverter) temperature stability control process A in FIG.
[0037]
When the control program starts (102), the control means 22 reads the temperature adjustment value output from the temperature adjustment means 40 (104).
[0038]
Then, a calculation (106) of the target compressor speed which is the compressor speed corresponding to the temperature adjustment value read by the control means 22 is executed.
[0039]
Further, the control means 22 reads the evaporator temperature of the compressor 4 detected by the compressor temperature sensor 26 (108), for example, the calculation of the compressor temperature stability control process (110), that is, the calculation of the compressor upper limit rotational speed described above. Operate with an expression.
[0040]
After this processing (110), it is determined (112) whether or not the target compressor speed is less than the compressor upper limit speed, and this determination (112) is NO, that is, the compressor upper limit speed and the target compressor speed. When the compressor upper limit rotational speed is lower, the compressor upper limit rotational speed is set as the target compressor rotational speed (114), and the compressor drive (116) is performed so as to become the target compressor rotational speed. The program returns (118).
[0041]
Further, if the determination (112) as to whether or not the target compressor speed is less than the compressor upper limit speed is YES, the compressor is driven so as to reach the target compressor speed without considering the compressor upper limit speed ( 116), and the process proceeds to the return (118) of the control program.
[0042]
Thereby, by using the compressor temperature sensor 26 as the temperature detecting means, it is possible to prevent overheating of the compressor 4 without performing overheat prevention control at the expense of normal air-conditioning control, which contributes to the improvement of commercial power. obtain.
[0043]
Further, if the inverter temperature sensor 30 is used as the temperature detecting means, the overheating of the inverter 24 can be prevented without performing the overheating prevention control at the expense of the normal air conditioning control, which can contribute to the improvement of the commercial power.
[0044]
Further, since it is possible to prevent a large fluctuation between the passenger compartment temperature and the blowout temperature due to the overheat prevention process, there is no possibility of causing discomfort to the occupant, which is practically advantageous.
[0045]
The present invention is not limited to the above-described embodiments, and various application modifications are possible.
[0046]
For example, in the embodiment of the present invention, the compressor upper limit rotational speed and the target compressor rotational speed are compared by the control means, and when the compressor upper limit rotational speed is higher, the compressor drive control is performed using the target compressor rotational speed. On the other hand, when the compressor upper limit rotational speed is lower, the compressor drive control is performed with the compressor upper limit rotational speed as the target compressor rotational speed. However, as the target compressor rotational speed approaches the compressor upper limit rotational speed, It is also possible to adopt a special configuration in which the target compressor rotational speed is corrected so as to gradually decrease.
[0047]
That is, a function for correcting the target compressor speed so that it gradually decreases as the target compressor speed approaches the compressor upper limit speed is added to the control means, and the compressor upper limit speed is used as much as possible. The compressor drive control is performed only with the target compressor speed.
[0048]
In other words, due to the correction by the control means, the operating state of the compressor (or inverter) gradually weakens, and even if the blowing temperature changes slightly, the passenger's inertia gives the passenger discomfort. There is not so much influence, the burden on the compressor (or inverter) can be reduced, the service life of the compressor (or inverter) can be extended, and the fuel consumption can be improved, which is economically advantageous.
[0049]
【The invention's effect】
As described in detail above, according to the present invention, overheating prevention control can be prevented without sacrificing normal air conditioning control, and overheating of the compressor can be prevented, which can contribute to improvement in commercial power.
[0050]
In addition, the inverter can be prevented from being overheated without performing overheat prevention control at the expense of normal air conditioning control, which can contribute to improving the product appeal.
[Brief description of the drawings]
FIG. 1 is a flowchart for controlling an air conditioner according to an embodiment of the present invention.
FIG. 2 is a block diagram of an air conditioner.
FIG. 3 is a schematic configuration diagram of an air conditioner.
[Explanation of symbols]
2 Air Conditioner 4 Compressor 6 Compressor Motor 8 Evaporator 12 Capacitor 14 Receiver 16 Expansion Valve 18 Capacitor Motor 20 Capacitor Fan 22 Control Unit 24 Inverter 26 Compressor Temperature Sensor 28 Compressor Motor Current Sensor 30 Inverter Temperature Sensor 32 Refrigerant Pressure Sensor 34 Evaporator Temperature sensor 36 Condenser motor current sensor 38 Outside air temperature sensor 40 Temperature adjusting means A Compressor (inverter) temperature stability control process B Compressor motor drive process command C Capacitor motor drive process command

Claims (2)

An air conditioner comprising at least a compressor driven by a motor and an evaporator that vaporizes refrigerant compressed by the compressor is provided with temperature detecting means for detecting the compressor temperature of the compressor, and is detected by the temperature detecting means. The compressor upper limit rotation speed is calculated based on the difference between the compressor temperature and the target compressor temperature set in advance separately from the temperature determined to be in a high temperature state, and is adapted to the arbitrarily set temperature. The target compressor speed is calculated, and the compressor upper limit speed and the target compressor speed are compared. If the compressor upper limit speed is lower, the compressor upper limit speed is set as the target compressor speed. If the upper speed limit is higher, the target control Air-conditioning system, characterized in that a control means for controlling the compressor driving to prevent large becomes variation of the temperature blows suppressor speed and directly used vehicle interior temperature. An air conditioner comprising at least a compressor driven by an inverter-controlled motor and an evaporator for vaporizing refrigerant compressed by the compressor is provided with temperature detecting means for detecting the inverter temperature of the inverter, and this temperature detecting means Compressor upper limit rotation speed is calculated based on the difference between the inverter temperature detected by the above and the temperature determined to be in a high temperature state, separately from the preset target inverter temperature, and it corresponds to the arbitrarily set temperature The target compressor speed is calculated, and the compressor upper limit speed and the target compressor speed are compared. If the compressor upper limit speed is lower, the compressor upper limit speed is set as the target compressor speed. On the other hand, if the compressor upper limit speed is higher, Air-conditioning system, characterized in that a control means for controlling the compressor driving to prevent large become variations of the temperature and blowing directly used vehicle interior temperature target compressor speed.

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