JP2010000964A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently control the temperature of the air having passed through a heat exchanger 9 for cooling. <P>SOLUTION: An electronic control device 70 increases control gains Kp, Ki compared to the case when a cooling load is determined to be small when the cooling load is determined to be large. The larger the control gains Kp, Ki become, the larger the control response of a refrigerant discharge capacity of a compressor 11 having a temperature deviation E(n) to be input becomes. When the cooling load is determined to be large, the control response of the refrigerant discharge capacity of the compressor 11 becomes large compared to the case when the cooling load is determined to be small. When the cooling load is large, the delay caused for reaching the target temperature TEO of the temperature of the air TE becomes short. When the cooling load is small, the control response of the refrigerant discharge capacity becomes small compared to the case when the cooling load is large, and therefore when the cooling load is small, hunting hardly occurs in controlling of the temperature of the air TE. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air conditioner including a compressor that compresses a refrigerant.

  Conventionally, in this type of air conditioner, as shown in Patent Document 1, for example, a variable capacity compressor configured to be able to vary the refrigerant discharge capacity, and the air in the vehicle interior by the refrigerant discharged from the variable capacity compressor are used. There is a cooling heat exchanger for cooling, and the room is cooled by air that has passed through the cooling heat exchanger.

  In this configuration, the electronic control unit controls the refrigerant discharge capacity of the variable capacity compressor, thereby changing the flow rate of the refrigerant flowing from the variable capacity compressor into the cooling heat exchanger. Thereby, the temperature of the air that has passed through the cooling heat exchanger can be controlled.

Therefore, a temperature sensor that detects the air temperature TE that has passed through the heat exchanger for cooling is provided, and the electronic control unit matches the detected temperature TE of the temperature sensor with the target temperature TEO by PID control (PID: Proportional Integral Difference). In this way, the refrigerant discharge capacity of the variable capacity compressor is controlled.
JP-A-5-58138

  In the above-described air conditioner, the electronic control unit controls the refrigerant discharge capacity of the variable capacity compressor based on the temperature deviation between the temperature detected by the temperature sensor TE and the target temperature TEO. Is delayed until the temperature TE detected by the temperature sensor reaches the target temperature TEO.

  In addition, when the electronic control unit controls the refrigerant discharge capacity of the variable displacement compressor, it may be possible to set the control gain of PID control so that the detected temperature TE of the temperature sensor quickly reaches the target temperature TEO. When the indoor cooling load is small, an overshoot in which the detected temperature TE of the temperature sensor exceeds the target temperature TEO or an undershoot in which the detected temperature TE is lower than the target temperature TEO occurs.

  In view of the above points, an object of the present invention is to provide an air conditioner that can favorably control the temperature of air that has passed through a cooling heat exchanger regardless of the size of an indoor cooling load.

In order to achieve the above object, according to the first aspect of the present invention, a command value is output to the compressor (11) every time the second calculating means (S180) calculates, and the refrigerant discharge amount of the compressor (11) is output. And a control means (S190) for controlling the refrigerant, the greater the control gain, the greater the control response of the refrigerant discharge amount, and the air that has passed through the cooling heat exchanger (9) An air conditioner for cooling,
Gain changing means (S170) is provided for changing the control gain so that the control response of the refrigerant discharge amount is larger when the cooling load in the room is large than when the cooling load is small. To do.

  Here, the control response is the ratio of the change amount of the command value to the temperature deviation. The amount of change in the command value is the deviation between the previous command value and the current command value.

  As described above, when the cooling load is large, the control response of the refrigerant discharge amount is larger than when the cooling load is small. Therefore, when the cooling load is large, the temperature sensor detects and reaches the target temperature. The delay that occurs is shortened.

  On the other hand, when the cooling load is small, the control response of the refrigerant discharge amount is smaller than when the cooling load is large. Therefore, when the cooling load is small, the control of the temperature of the air that has passed through the cooling heat exchanger is performed. Overshoot and undershoot are less likely to occur.

  As described above, the temperature of the air that has passed through the cooling heat exchanger can be favorably controlled regardless of the size of the indoor cooling load.

In the invention which concerns on Claim 2, the flow sensor (76) which detects the refrigerant | coolant amount which flows between the said compressor (11) and the said heat exchanger for cooling (9) is provided,
When the refrigerant amount detected by the flow sensor (76) is greater than or equal to a predetermined value, the cooling load is assumed to be large, and when the refrigerant amount detected by the flow sensor (76) is less than a predetermined value, The cooling load is small.

In the invention which concerns on Claim 3, the estimation means (S161) which estimates the refrigerant | coolant amount which flows between the said compressor (11) and the said heat exchanger for cooling (9) is provided,
When the refrigerant amount estimated by the estimating means (S161) is greater than or equal to a predetermined value, the cooling load is assumed to be large, and when the refrigerant amount estimated by the estimating means (S161) is less than a predetermined value, The cooling load is small.

In the invention which concerns on Claim 4, the cooler (12) which cools the refrigerant | coolant discharged from the said compressor (11),
A decompressor (14) disposed between a refrigerant outlet of the cooler (12) and a refrigerant inlet of the cooling heat exchanger (9), and decompresses the refrigerant cooled by the cooler (12);
A pressure sensor for detecting a refrigerant pressure between a refrigerant discharge port of the compressor (11) and a refrigerant inlet of the decompressor (14),
When the detected pressure of the pressure sensor is greater than or equal to a predetermined value, the cooling load is large, and when the detected pressure of the pressure sensor is less than a predetermined value, the cooling load is small.

In the invention which concerns on Claim 5, the cooler (12) which cools the refrigerant | coolant discharged from the said compressor (11),
A decompressor (14) disposed between a refrigerant outlet of the cooler (12) and a refrigerant inlet of the cooling heat exchanger (9), and decompresses the refrigerant cooled by the cooler (12);
A pressure sensor for detecting a refrigerant pressure between a refrigerant discharge port of the compressor (11) and a refrigerant inlet of the pressure reducer (14),
The compressor (11) compresses the refrigerant by a rotational force output from a drive source,
A rotation speed sensor for detecting the rotation speed of the compressor (11);
The detected pressure of the pressure sensor is equal to or higher than a predetermined value, the detected temperature of the temperature sensor (75) is equal to or higher than a predetermined temperature, the detected rotational speed of the rotational speed sensor is equal to or higher than a predetermined rotational speed, and the refrigerant discharge amount When the command value is greater than or equal to a predetermined value, it is assumed that the cooling load is large,
When the detected pressure of the pressure sensor is less than a predetermined value, when the detected temperature of the temperature sensor (75) is less than a predetermined temperature, and when the detected rotational speed of the rotational speed sensor is less than a predetermined rotational speed The cooling load is small in at least one of the cases where the command value of the refrigerant discharge amount is less than a predetermined value.

In the invention according to claim 6, the current command value is Iout (n), the previous command value is Iout (n-1), the current temperature deviation is E (n), and the previous temperature deviation is E (N-1), where the first coefficient is Kp and the second coefficient is Ki, the calculation means repeatedly calculates the command value Iout (n) based on the following Equation 1. And
Iout (n) = Iout (n-1)
+ Kp × (E (n) −E (n−1)) + Ki × E (n)...
The gain changing means (170) is characterized in that at least one of the first and second coefficients is changed to Kp and Ki as the control gain.

  In the invention according to claim 7, when the first constant is a1, the second constant is a2, the variable is α, and Kp = a1 × α and Ki = a2 × α are established, the gain changing means ( 170) is characterized in that each of the first and second coefficients is changed as the control gain by changing the variable α.

In the invention according to claim 8, the current command value is Iout (n), the previous command value is Iout (n-1), the current temperature deviation is E (n), and the previous temperature deviation is E (N-1), where the temperature deviation of the previous time is E (n-2), the first coefficient is Kp, the second coefficient is Ki, and the third coefficient is Kd, The command value Iout (n) is repeatedly calculated based on Formula 2,
Iout (n) = Iout (n−1) + Kp × (E (n) −E (n−1))
+ Ki × E (n)
+ Kd * ((E (n) -E (n-1))-(E (n-1) -E (n-2))) Equation 2
The gain changing means (170) changes at least one of the first, second, and third coefficients as the control gain.

  In the invention according to claim 9, the first constant is a1, the second constant is a2, the third constant is a3, the variable is α, and Kp = a1 × α, Ki = a2 × α, and Kd = a3 When xα is established, the gain changing means (170) changes each of the first, second, and third coefficients Kp, Ki, and Kd as the control gain by changing the variable α. It is characterized by doing.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the overall configuration of this embodiment.

  The vehicle air conditioner includes an indoor air conditioning unit 1 disposed inside the instrument panel at the forefront of the vehicle interior. The indoor air conditioning unit 1 has an air conditioning casing 2. The air conditioning casing 2 constitutes an air passage through which air is blown toward the vehicle interior.

  An inside / outside air switching box 5 having an inside air introduction port 3 and an outside air introduction port 4 is arranged in the most upstream part of the air passage of the air conditioning casing 2. An inside / outside air switching door 6 is rotatably supported in the inside / outside air switching box 5. The inside / outside air switching door 6 is driven by a servo motor 7 and opens at least one of the inside air introduction port 3 and the outside air introduction port 4.

  On the downstream side of the inside / outside air switching box 5, an electric blower 8 that blows air toward the passenger compartment is disposed. The blower 8 drives a centrifugal blower fan 8a by a motor 8b. A cooling heat exchanger 9 for cooling the blown air is disposed on the downstream side of the blower 8.

  The cooling heat exchanger 9 constitutes a known refrigeration cycle apparatus 10 together with the compressor 11, the condenser 12, the gas-liquid separator 13, and the expansion valve 14, and cools the blown air blown from the blower 8. It is.

  The compressor 11 is rotationally driven by the rotational power of the vehicle engine E transmitted through the pulley 11a and the belt 11c, and sucks, compresses, and discharges the refrigerant.

  The compressor 11 of the present embodiment is a swash plate type variable displacement compressor including an electromagnetic valve 11b that continuously varies the refrigerant discharge capacity according to a command value Iout from the outside. The refrigerant discharge capacity of the compressor 11 increases as the command value Iout increases.

  The condenser 12 is a cooler that cools the refrigerant by exchanging heat between the refrigerant discharged from the compressor 11 and the outside air blown by a blower fan (not shown). The gas-liquid separator 13 separates the refrigerant cooled by the condenser 12 into a gas phase refrigerant and a liquid phase refrigerant. The expansion valve 14 decompresses and expands the liquid-phase refrigerant separated by the gas-liquid separator 13.

  The cooling heat exchanger 9 cools the air blown from the blower 8 by exchanging heat between the refrigerant decompressed and expanded by the expansion valve 14 and the blown air blown from the blower 8.

  The indoor air conditioning unit 1 is provided with a heater core 15 that heats the cold air blown out from the cooling heat exchanger 9. The heater core 15 is a heating heat exchanger that heats the cold air from the cooling heat exchanger 9 by using the cooling water of the vehicle engine 11d as a heat source. A bypass passage 16 is formed on the side of the heater core 15, and air bypassed by the heater core 15 flows through the bypass passage 16.

  An air mix door 17 is rotatably supported between the cooling heat exchanger 9 and the heater core 15. The air mix door 17 constitutes a temperature adjustment unit together with the heater core 15 and the bypass passage 16 and is driven by a servo motor 18.

  The ratio of the amount of air that passes through the heater core 15 (warm air amount) and the amount of air that passes through the bypass passage 16 and bypasses the heater core 15 (cold air amount) is adjusted by the opening of the air mix door 17, The temperature of the blown out air is adjusted.

  A defroster opening 19 for blowing conditioned air toward the front window glass W of the vehicle and a face opening 20 for blowing conditioned air toward the occupant's face are provided at the most downstream portion of the air passage of the air conditioning casing 2. In addition, a total of three types of openings, that is, a foot opening 21 for blowing conditioned air toward the feet of the occupant are provided.

  A defroster door 22, a face door 23, and a foot door 24 are rotatably disposed upstream of the openings 19-21. The doors 22 to 24 are opened and closed by a common servo motor 25 via a link mechanism (not shown). The face opening 20 communicates with the face outlet of the instrument panel via a duct (not shown).

  Next, the electrical configuration of the vehicle air conditioner of this embodiment will be described with reference to FIG.

  The vehicle air conditioner includes an electronic control unit 70, an outside air sensor 71, an inside air sensor 72, a solar radiation sensor 73, a water temperature sensor 74, a cooling heat exchanger temperature sensor 75, a flow rate sensor 76, and an air conditioning operation panel 80.

  The outside air sensor 71 is a sensor that detects the outside air temperature Tam. The inside air sensor 72 is a sensor that detects the inside air temperature Tr. The solar radiation sensor 73 is a sensor that detects the solar radiation amount Ts incident on the vehicle interior. The water temperature sensor 74 is a sensor that detects the cooling water temperature Tw of the engine 11d.

  The cooling heat exchanger temperature sensor 75 is a temperature sensor that detects the air temperature TE that has passed through the cooling heat exchanger 9. The flow sensor 76 is disposed between the refrigerant outlet of the compressor 11 and the refrigerant inlet of the condenser 12 and detects the refrigerant flow G flowing from the compressor 11 to the condenser 12.

  The air conditioning operation panel 80 includes a temperature setting switch 80a for setting a desired temperature Tset in the passenger compartment, an AC switch 80b for setting operation and stop of the compressor 11, and the like.

  The electronic control unit 70 includes a microcomputer and a memory. The microcomputer executes the air conditioning control process, and in accordance with the execution of the air conditioning control process, based on the output signals of the sensors 71, 72... 75 and the output signal of the air conditioning operation panel 80, the electromagnetic valve 11b and the motors 7, 8b, 18 and 25 are controlled. In addition to the computer program, various data are stored in the memory.

  Next, the operation of this embodiment will be described with reference to FIGS.

  First, the general operation of the air conditioning control process by the electronic control unit 70 will be described.

  That is, the refrigerant discharge capacity of the compressor 11 is controlled so that the blown air temperature TE approaches the target temperature TEO. Details of the evaporator temperature control of the compressor 11 will be described later.

  Subsequently, the target blown air temperature TAO is calculated by substituting the desired temperature Tset, the inside air temperature Tr, the outside air temperature Tam, and the solar radiation amount Ts into Equation 3. The target blowing air temperature TAO is a target blowing temperature from the face outlets 31 to 34 that is necessary for the detected temperature Tr of the temperature sensor to maintain the desired temperature Tset.

TAO = Kset × Tset−KR × Tr
−KAM × Tam−KS × Ts + C (Formula 1)
Kset, KR, KAM, and KS are gains, and C is a correction constant.

  Subsequently, the servo motor 7 is controlled based on the target blown air temperature TAO. Accordingly, at least one of the inside air introduction port 3 and the outside air introduction port 4 is opened by the inside / outside air switching door 6. For example, when the target blowing air temperature TAO is equal to or lower than a predetermined temperature and the cooling operation is being performed, only the inside air introduction port 3 is opened by the inside / outside air switching door 6.

  Further, the target rotational speed Na of the motor 8b of the blower 8 is obtained based on the target blown air temperature TAO. In addition, the motor 8b is controlled so that the rotational speed of the motor 8b of the blower 8 approaches the target rotational speed Na. Thereby, the air volume of the air blower 8 approaches the target air volume.

  Further, the servo motor 25 is controlled based on the target blown air temperature TAO to open and close the defroster door 22, the face door 23, and the foot door 24, respectively.

  Next, the target opening temperature SW of the air mix door 17 is calculated by substituting the target blowing air temperature TAO, the blowing air temperature TE of the cooling heat exchanger 9 and the engine cooling water temperature Tw into Equation 4.

SW = {(TAO−TE) / (Tw−TE)} × 100 (%) (Equation 2)
Subsequently, the servo motor 18 is controlled so that the opening degree of the air mix door 17 approaches the target opening degree SW. Thereby, the air temperature blown out from the openings 19 to 21 approaches the target blown air temperature TAO.

  Next, details of the evaporator temperature control of the compressor 11 of the present embodiment will be described with reference to FIGS. 2 and 3 are flowcharts showing the evaporator temperature control.

  The electronic control unit 70 performs evaporator temperature control according to the flowcharts of FIGS. When the AC switch 80b is turned on, execution of the evaporator temperature control is started. The execution of the evaporator temperature control is repeated.

  First, in step S100, the number n of executions of the control process is set to 1, and the temperature deviation E (n-1) (= E (0)) is set to 0 in the next step S110. The temperature deviation E (n−1) is an initial value of the temperature deviation between the air temperature TE and the target temperature TEO. The target temperature TEO is the target temperature of the blown air temperature from the heat exchanger temperature sensor 75 for cooling.

  In the next step S120, the inside air temperature Tr, the outside air temperature Tam, and the solar radiation amount Ts are taken in from the sensors 71, 72, 73. Subsequently, in step S130, the target temperature TEO (n) is calculated based on the inside air temperature Tr, the outside air temperature Tam, and the solar radiation amount Ts.

  In the next step 140, the air temperature TE (n) is taken from the cooling heat exchanger temperature sensor 75. The air temperature TE (n) is the temperature detected by the nth cooling heat exchanger temperature sensor 75.

  In the next step 150, a temperature deviation E (n) (= TE (n) −TEO (n)) between the air temperature TE (n) and the target temperature TEO (n) is obtained.

  In the next step S160, the refrigerant flow rate G is taken from the flow rate sensor 76. Subsequently, in step S170, control gains Kp and Ki are determined from the refrigerant flow rate G.

  First, as the control gain Kp, one of the two values Kp1 and Kp2 is determined according to the refrigerant flow rate G. The value Kp2 is larger than the value Kp1. Hysteresis is set when determining the control gain Kp. For example, when the refrigerant flow rate G exceeds the threshold value G2, the value Kp2 is determined as the control gain Kp. When the refrigerant flow rate G falls below the threshold value G1, the value Kp1 is determined as the control gain Kp. The threshold G2 is larger than the threshold G1 (<G2).

  Thus, when the refrigerant flow rate G is larger than the threshold value G2, the control gain Kp is increased as compared with the case where the refrigerant flow rate G is smaller than the refrigerant flow rate G1.

  Further, as the control gain Ki, one of the two values Ki1, Ki2 (> Kp1) is determined according to the refrigerant flow rate G. The value Ki2 is larger than the value Ki1. Hysteresis is set when determining the control gain Ki. For example, when the refrigerant flow rate G exceeds the threshold G4, the value Ki2 is determined as the control gain Ki. When the refrigerant flow rate G falls below the threshold G3, the value Ki1 is determined as the control gain Ki. The threshold value G4 is larger than the threshold value G3 (<G4).

  Thus, when the refrigerant flow rate G is larger than the threshold value G4, the control gain Ki is smaller than when the refrigerant flow rate G is smaller than the refrigerant flow rate G3.

  Next, in step S180 of FIG. 3, the previous command value is Iout (n-1), the current temperature deviation is E (n), and the previous temperature deviation is E (n-1). The current command value Iout (n) in the discharge capacity is calculated based on Equation 1.

Iout (n) = Iout (n-1)
+ Kp × (E (n) −E (n−1)) + Ki × E (n) (Equation 3)
In the next step S190, the current command value Iout (n) is output to the electromagnetic valve 11b of the compressor 11. Thereby, the solenoid valve 11b is driven and the refrigerant discharge capacity of the compressor 11 is controlled. That is, the refrigerant discharge capacity of the compressor 11 is controlled by PI control.

  Next, in step S200, it is determined whether or not to continue the evaporator temperature control. When the AC switch 80b is off, NO is determined in step S200. Then, it progresses to step S210 and the said evaporator temperature control is complete | finished.

  When the AC switch 80b is turned on, YES is determined in step S200. Accordingly, in the next step S220, the command value Iout (n) is substituted for the command value Iout (n-1). In the next step S230, the temperature deviation E (n) is substituted into the temperature deviation E (n-1). In the next step S230, the value of the number of executions n is incremented by 1 (n = n + 1).

  Thereafter, the process proceeds to step S120 in FIG. 2, and using the command value Iout (n-1) and the temperature deviation E (n-1), steps S120, S130, S140, S150, S160, S170, The processes of S180, S190, and S200 are repeated.

  As a result, as long as the AC switch 80b is turned on, the refrigerant discharge capacity of the compressor 11 is controlled according to the command value Iout (n). The compressor 11 is driven by the rotational power of the vehicle engine E, and sucks, compresses, and discharges the refrigerant.

  The refrigerant discharged from the compressor 11 is condensed and cooled by the condenser 12. The cooled refrigerant is separated into a gas phase refrigerant and a liquid phase refrigerant by the gas-liquid separator 13. The expansion valve 14 decompresses and expands the liquid-phase refrigerant separated by the gas-liquid separator 13. The decompressed and expanded refrigerant flows into the cooling heat exchanger 9. The cooling heat exchanger 9 cools the air blown from the blower 8 as the refrigerant from the expansion valve 14 evaporates.

  Here, in the cooling heat exchanger 9, the amount of refrigerant flowing from the expansion valve 14 varies depending on the refrigerant discharge capacity of the compressor 11 as described above. The refrigerant discharge capacity is controlled by the command value Iout (n).

  Here, the control gains Kp and Ki used when calculating the command value Iout (n) are switched based on the refrigerant flow rate G.

  That is, when the refrigerant flow rate G is larger than the threshold value G2, the control gain Kp is larger than when the refrigerant flow rate G is smaller than the refrigerant flow rate G1. When the refrigerant flow rate G is larger than the threshold value G4, the control gain Ki is smaller than when the refrigerant flow rate G is smaller than the refrigerant flow rate G3.

  Here, the refrigerant flow rate G is information indicating the cooling load in the passenger compartment. When the refrigerant flow rate G is larger than the threshold value G2, it is determined that the cooling load is large, and when the refrigerant flow rate G is smaller than the threshold value G1, it is determined that the cooling load is small. For this reason, when it is determined that the cooling load is large, the control gain Kp is larger than when it is determined that the cooling load is small. Details of the determination of the magnitude of the cooling load will be described later.

  On the other hand, when the refrigerant flow rate G becomes larger than the threshold value G4, it is determined that the cooling load is large, and when the refrigerant flow rate G becomes smaller than the threshold value G3, it is determined that the cooling load is small. For this reason, when the cooling load is large, the control gain Ki is larger than when the cooling load is small.

  Here, as the control gains Kp and Ki increase, the control response in the refrigerant discharge capacity of the compressor 11 increases. The control response is a ratio of the change amount ΔI of the command value with respect to the temperature deviation E (n). The change amount ΔI of the command value is a deviation (Iout (n) −Iout (n−1)) between the current command value Iout (n) and the previous command value Iout (n−1).

  According to the present embodiment described above, when it is determined that the cooling load is large, the control gains Kp and Ki are larger than when it is determined that the cooling load is small. As the control gains Kp and Ki increase, the control response of the refrigerant discharge capacity of the compressor 11 increases.

  For this reason, when it determines with the cooling load being large, compared with the case where it determines with the cooling load being small, the control response of the refrigerant | coolant discharge capacity of the compressor 11 becomes large. That is, when it is determined that the cooling load is large, the control response of the discharged refrigerant flow rate of the compressor 11 is greater than when it is determined that the cooling load is small. For this reason, when the cooling load is large, the delay that occurs when the air temperature TE reaches the target temperature TEO is shortened.

  On the other hand, when the cooling load is small, the control response of the refrigerant discharge amount is smaller than when the cooling load is large. Therefore, when the cooling load is small, overshoot and undershoot may occur when controlling the air temperature TE. It becomes difficult to occur. That is, hunting is less likely to occur when controlling the air temperature TE.

  As described above, the temperature of the air that has passed through the cooling heat exchanger 9 can be favorably controlled regardless of the size of the cooling load.

  Next, the determination of the magnitude of the cooling load will be described.

  For example, the inside air introduction port 3 is opened by the inside / outside air switching door 6 when the cooling operation in the passenger compartment is being performed. For this reason, the inside air introduced through the inside air inlet 3 flows to the cooling heat exchanger 9.

  When the cooling load in the passenger compartment is small, the cold air blown out from the face air outlet causes the indoor temperature Tr to decrease in a short period, so the temperature deviation E (n) decreases in a short period. For this reason, the refrigerant | coolant discharge capacity of the compressor 11 becomes small, and the refrigerant | coolant flow volume G becomes smaller than threshold value G1, G3.

  On the other hand, when the cooling load is large, there is a delay in reducing the room temperature Tr even if the cool air is blown out from the face outlet. For this reason, the temperature deviation E (n) increases, and the refrigerant discharge capacity of the compressor 11 increases. Therefore, the refrigerant flow rate G becomes larger than the threshold values G2 and G4.

  As described above, in the present embodiment, when the refrigerant flow rate G is larger than the threshold values G2 and G4, it is determined that the cooling load is large, and when the refrigerant flow rate G is smaller than the threshold values G1 and G3, it is determined that the cooling load is small. .

(Second Embodiment)
In the above-described first embodiment, an example in which the magnitude of the cooling load is determined based on the refrigerant flow rate G detected by the flow sensor has been described. Instead, in the second embodiment, the refrigerant flow rate G is estimated. The magnitude of the cooling load is determined using the value. Hereinafter, the estimated value of the refrigerant flow rate G is referred to as an estimated refrigerant threshold value g.

  In the present embodiment, a rotation sensor for detecting the rotation speed of the vehicle engine 11d is used. The rotation speed of the vehicle engine 11d is used as the rotation speed Na of the compressor 11.

  A high pressure sensor that detects the refrigerant pressure Ph between the refrigerant discharge port of the compressor 11 and the refrigerant inlet of the expansion valve 14 is used. A low pressure sensor that detects the refrigerant pressure Ps between the refrigerant inlet of the compressor 11 and the refrigerant outlet of the expansion valve 14 is used.

  The electronic control device 70 according to the present embodiment performs evaporator temperature control according to the flowcharts of FIGS. 4 and 5.

  In FIG. 4, step S161 is used instead of step S160 in FIG. In FIG. 5, step S171 is used instead of step S170 in FIG.

  In step S161 of FIG. 4, the estimated refrigerant threshold value g is obtained by substituting the refrigerant pressure Ph, the refrigerant pressure Ps, the rotation speed Na, and the previous command value I (n) into the following equation 4.

g = (Ph−Ps) × Nc × I (n−1) (4)
In step S171 in FIG. 5, control gains Kp and Ki are determined based on the estimated refrigerant threshold value g. The method for determining the control gains Kp and Ki is the same as in step S170 of FIG.

  Steps other than steps S161 and S171 in the flowcharts in FIGS. 4 and 5 are the same as those in FIGS.

  In the present embodiment described above, the control gains Kp and Ki are determined using the estimated refrigerant threshold value g. Therefore, similarly to the above-described first embodiment, when it is determined that the cooling load is large, the control response of the refrigerant discharge capacity of the compressor 11 is greater than when it is determined that the cooling load is small. For this reason, the air temperature which passed the heat exchanger 9 for cooling can be favorably controlled irrespective of the magnitude of the cooling load.

(Third embodiment)
In the above-described first embodiment, the example in which the threshold value of the refrigerant flow rate G used for determining the control gains Kp and Ki is provided for each control gain is shown, but instead, control is performed using a common threshold value. The third embodiment in which the gains Kp and Ki are changed will be described.

  The electronic control device 70 of the present embodiment executes evaporator temperature control according to the flowcharts of FIGS. 6 and 7.

  In FIG. 6, step S172 is used instead of step S170 in FIG. In FIG. 7, step S182 is used instead of step S180 in FIG.

  In step S172 of FIG. 6, a coefficient α used for changing control gains Kp and Ki, which will be described later, is determined based on the refrigerant flow rate G.

  Specifically, as the coefficient α, one of the two values α1 and α2 is determined according to the refrigerant flow rate G. The value α2 is larger than the value α1. Hysteresis is set when the coefficient α is determined. For example, when the refrigerant flow rate G exceeds the threshold G2, the value α2 is determined as the coefficient α. When the refrigerant flow rate G falls below the threshold value G1, the value α1 is determined as the coefficient α. The threshold value G2 is larger than the threshold value G1.

  Next, in step S182 in FIG. 7, the control gains Kp and Ki are determined using the coefficient α.

  Specifically, the control gains Kp and Ki are determined using the following formulas 5 and 6.

Kp = a1 × α ... Formula 5
Ki = a2 × α Equation 6
Here, a1 is a first constant, and a2 is a second constant.

  Therefore, when the refrigerant flow rate G exceeds the threshold G2, Kp = a1 × α2, and when the refrigerant flow rate G falls below the threshold G1, Kp = a1 × α1. In addition, when the refrigerant flow rate G exceeds the threshold G2, Ki = a2 × α2, and when the refrigerant flow rate G falls below the threshold G1, Ki = a2 × α1.

  In the present embodiment described above, the control gains Kp and Ki can be changed using the common threshold values G1 and G2. That is, it is determined whether the cooling load is large using the common threshold values G1 and G2.

(Fourth embodiment)
In the above-described first embodiment, the example in which the magnitude of the cooling load is determined based on the refrigerant flow rate G detected by the flow sensor is shown. Instead, in the fourth embodiment,
It is determined whether or not the cooling load is large using the refrigerant pressure or the like.

  In the present embodiment, a rotation sensor for detecting the rotation speed of the vehicle engine 11d is used. The rotation speed of the vehicle engine 11d is used as the rotation speed Na of the compressor 11. A high pressure sensor that detects the refrigerant pressure Ph between the refrigerant discharge port of the compressor 11 and the refrigerant inlet of the expansion valve 14 is used.

  The electronic control device 70 according to the present embodiment performs evaporator temperature control according to the flowcharts of FIGS.

  In FIG. 8, step S163 is used instead of step S160 in FIG. In FIG. 9, step S173 is used instead of step S170 in FIG.

  In step S163 of FIG. 8, the magnitude of the refrigerant flow rate g 'is determined based on the refrigerant pressure Ph, the rotation speed Na, the air temperature TE (n), and the previous command value I (n-1).

  The refrigerant pressure Ph is equal to or higher than the predetermined pressure Pd, the rotation speed Na is equal to or higher than the predetermined rotation speed Nc, the air temperature TE (n) is equal to or higher than the predetermined temperature t, and the previous command value I (n−1) is a predetermined value. When it is equal to or greater than I, it is determined that the refrigerant flow rate g ′ is large. That is, it is determined that the cooling load is large.

  On the other hand, when the refrigerant pressure Ph is less than the predetermined pressure Pd, when the rotation speed Na is less than the predetermined rotation speed Nc, when the air temperature TE (n) is less than the predetermined temperature t, the previous command value I It is determined that the refrigerant flow rate g ′ is small in at least one of the cases where (n−1) is less than the predetermined value I. That is, it is determined that the cooling load is small. The reason why the refrigerant flow rate g ′ is determined based on the refrigerant pressure Ph and the like will be described later.

  In step S173 of FIG. 9, the control gains Kp and Ki are determined based on the magnitude of the cooling load. When it is determined that the cooling load is large, Kp = Kp2 and Ki = Ki2, and when it is determined that the cooling load is small, Kp = Kp1 and Ki = Ki1.

  Here, the values Kp1, Kp2, Ki1, and Ki2 are the same as the values Kp1, Kp2, Ki1, and Ki2 of the first embodiment described above.

  Therefore, when it is determined that the cooling load is large, the control gains Kp and Ki are larger than when it is determined that the cooling load is small. Therefore, similarly to the first embodiment described above, the temperature of the air that has passed through the cooling heat exchanger 9 can be favorably controlled regardless of the cooling load.

  Next, the reason why the refrigerant flow rate g ′ is determined based on the refrigerant pressure Ph or the like in the present embodiment will be described.

First, when the cooling load is large, even if cool air is blown from the face outlet, a delay occurs in reducing the room temperature Tr. Along with this, there is a delay in reducing the temperature of the air introduced from the inside air inlet 3. For this reason, the air temperature TE (n) becomes higher than the predetermined temperature t, and the temperature deviation E (n) becomes large. Accordingly, the previous command value I (n−1) becomes a value larger than the predetermined value I in order to reduce the temperature deviation E (n). Therefore, the rotation speed Na of the compressor 11 is larger than the predetermined rotation speed Nc, and the refrigerant discharge capacity of the compressor 11 is increased. Therefore, the refrigerant pressure Ph becomes higher than the predetermined pressure Pd.

  Thus, when the refrigerant pressure Ph ≧ Pd, the rotational speed Na ≧ Nc, TE (n) ≧ t, and I (n−1) ≧ I, it is determined that the cooling load in the vehicle compartment is large.

  On the other hand, when the cooling load is small, the indoor temperature Tr decreases in a short period of time due to the cool air blown from the face air outlet, so the air temperature TE (n) becomes lower than the predetermined temperature t, and the temperature deviation becomes E (n ) Becomes smaller. Accordingly, the previous command value I (n−1) becomes a value smaller than the predetermined value I in order to maintain the temperature deviation E (n). Therefore, the rotation speed Na of the compressor 11 becomes smaller than the predetermined rotation speed Nc, and the refrigerant discharge capacity of the compressor 11 becomes small. Therefore, the refrigerant pressure Ph becomes lower than the predetermined pressure Pd.

  Thus, when any one of the refrigerant pressure Ph <Pd, the rotation speed Na <Nc, TE (n) <t, and I (n−1) <I is determined, it is determined that the cooling load in the passenger compartment is small. To do.

(Other embodiments)
In the above-described first to fourth embodiments, the example in which the control gains Kp and Ki used in Equation 3 are changed based on the refrigerant flow rate G is shown. Instead of this, any of the control gains Kp and Ki is used. One of them may be changed based on the cooling load.

  In the first to fourth embodiments described above, the example in which the refrigerant discharge capacity of the compressor 11 is controlled by PI control has been shown. Instead, the refrigerant discharge capacity of the compressor 11 is controlled by PID control. May be.

  That is, the current command value is Iout (n), the previous command value is Iout (n-1), the current temperature deviation is E (n), the previous temperature deviation is E (n-1), and the previous temperature deviation. Is E (n-2) and the control gain is Kp, Ki, Kd, the electronic control unit 70 repeatedly calculates the command value Iout (n) based on the following Equation 4 in step S180 in FIG. To do.

Iout (n) = Iout (n−1) + Kp × (E (n) −E (n−1))
+ Ki × E (n)
+ Kd * ((E (n) -E (n-1))-(E (n-1) -E (n-2))) Equation 7
The electronic control unit 70 may change the control gains Kp, Ki, and Kd based on the cooling load as in the following (1) and (2).

  (1) The control gains Kp and Ki are determined by the refrigerant flow rate G as in the first embodiment described above. As the control gain Kd, one of the two values Kd1 and Kd2 is determined according to the refrigerant flow rate G. The value Kd2 is larger than the value Kd1. For example, when the refrigerant flow rate G exceeds the threshold value G2, the value Kd2 is determined as the control gain Kd. When the refrigerant flow rate G falls below the threshold value G1, the value Kd1 is determined as the control gain Kd. The threshold G2 is larger than the threshold G1 (<G2).

  (2) As in the third embodiment described above, one of the two values α1 and α2 is determined as the coefficient α according to the refrigerant flow rate G. Accordingly, when the first constant is a1, the second constant is a2, and the third constant is a3, the control gains Kp, Ki, and Kd are calculated using the following equations 8, 9, and 10. Decide.

Kp = a1 × α Equation 8
Ki = a2 × α Equation 9
Kd = a3 × α Equation 10
In each of the above-described embodiments, an example in which the air conditioner according to the present invention is applied to a vehicle air conditioner has been described. However, the present invention is not limited thereto, and the air conditioner according to the present invention may be applied to an installation type air conditioner.

  In each of the above-described embodiments, an example in which a variable capacity compressor is used as the compressor 11 according to the present invention has been described. An electric compressor may be used.

It is a figure showing the whole vehicle air-conditioner composition in a 1st embodiment of the present invention. It is a flowchart which shows a part of control process of the electronic controller of FIG. It is a flowchart which shows the remainder of the control processing of the electronic controller of FIG. It is a flowchart which shows a part of control process of the electronic controller in 2nd Embodiment of this invention. It is a flowchart which shows the remainder of the control processing of the electronic controller in 2nd Embodiment. It is a flowchart which shows a part of control process of the electronic controller in 3rd Embodiment of this invention. It is a flowchart which shows the remainder of the control processing of the electronic controller in 3rd Embodiment. It is a flowchart which shows a part of control process of the electronic controller in 4th Embodiment of this invention. It is a flowchart which shows the remainder of the control processing of the electronic controller in 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Indoor air-conditioning unit 2 Air-conditioning casing 8 Blower 9 Heat exchanger for cooling 10 Refrigeration cycle apparatus 11 Compressor 11d Vehicle engine 12 Condenser 13 Gas-liquid separator 14 Expansion valve 15 Heater core 16 Bypass passage 17 Air mix door 70 Electronic controller 71 Outside air sensor 72 Inside air sensor 73 Solar radiation sensor 74 Water temperature sensor 75 Heat exchanger temperature sensor for cooling 76 Flow rate sensor 80 Air conditioning operation panel

Claims (9)

A compressor (11) configured to compress and discharge the refrigerant and change the refrigerant discharge amount;
A cooling heat exchanger (9) that constitutes a refrigeration cycle apparatus together with the compressor (11), evaporates the refrigerant and cools the air;
A temperature sensor (75) for detecting the temperature of the air that has passed through the cooling heat exchanger (9);
First calculation means (S150) for repeatedly calculating a temperature deviation between a temperature detected by the temperature sensor (75) and a target temperature;
Second calculation means (S180) for calculating, using a control gain, a command value for the refrigerant discharge amount of the compressor (11) that reduces the temperature deviation each time the first calculation means (S150) is calculated;
Control means (S190) for controlling the refrigerant discharge amount of the compressor (11) by outputting the command value to the compressor (11) each time the second calculation means (S180) is calculated,
As the control gain increases, the control response of the refrigerant discharge amount increases.
An air conditioner that cools a room with air that has passed through the cooling heat exchanger (9),
Gain changing means (S170) is provided for changing the control gain so that the control response of the refrigerant discharge amount is larger when the cooling load in the room is large than when the cooling load is small. Air conditioner to do. A flow sensor (76) for detecting the amount of refrigerant flowing between the compressor (11) and the cooling heat exchanger (9);
When the refrigerant amount detected by the flow sensor (76) is greater than or equal to a predetermined value, the cooling load is assumed to be large, and when the refrigerant amount detected by the flow sensor (76) is less than a predetermined value, The air conditioning apparatus according to claim 1, wherein the cooling load is small. Estimating means (S161) for estimating the amount of refrigerant flowing between the compressor (11) and the cooling heat exchanger (9),
When the refrigerant amount estimated by the estimating means (S161) is greater than or equal to a predetermined value, the cooling load is assumed to be large, and when the refrigerant amount estimated by the estimating means (S161) is less than a predetermined value, The air conditioning apparatus according to claim 1, wherein the cooling load is small. A cooler (12) for cooling the refrigerant discharged from the compressor (11);
A decompressor (14) disposed between a refrigerant outlet of the cooler (12) and a refrigerant inlet of the cooling heat exchanger (9), and decompresses the refrigerant cooled by the cooler (12);
A pressure sensor for detecting a refrigerant pressure between a refrigerant discharge port of the compressor (11) and a refrigerant inlet of the decompressor (14),
The cooling load is assumed to be large when the detected pressure of the pressure sensor is equal to or greater than a predetermined value, and the cooling load is assumed to be small when the detected pressure of the pressure sensor is less than a predetermined value. Item 2. The air conditioner according to item 1. A cooler (12) for cooling the refrigerant discharged from the compressor (11);
A decompressor (14) disposed between a refrigerant outlet of the cooler (12) and a refrigerant inlet of the cooling heat exchanger (9), and decompresses the refrigerant cooled by the cooler (12);
A pressure sensor for detecting a refrigerant pressure between a refrigerant discharge port of the compressor (11) and a refrigerant inlet of the decompressor (14),
The compressor (11) compresses the refrigerant by a rotational force output from a drive source,
A rotation speed sensor for detecting the rotation speed of the compressor (11);
The detected pressure of the pressure sensor is equal to or higher than a predetermined value, the detected temperature of the temperature sensor (75) is equal to or higher than a predetermined temperature, the detected rotational speed of the rotational speed sensor is equal to or higher than a predetermined rotational speed, and the refrigerant discharge amount When the command value is greater than or equal to a predetermined value, it is assumed that the cooling load is large,
When the detected pressure of the pressure sensor is less than a predetermined value, when the detected temperature of the temperature sensor (75) is less than a predetermined temperature, and when the detected rotational speed of the rotational speed sensor is less than a predetermined rotational speed 2. The air conditioner according to claim 1, wherein the cooling load is small in at least one of a case where the command value of the refrigerant discharge amount is less than a predetermined value. The current command value is Iout (n), the previous command value is Iout (n−1), the current temperature deviation is E (n), the previous temperature deviation is E (n−1), and the first When the coefficient of Kp is Kp and the second coefficient is Ki, the calculation means repeatedly calculates the command value Iout (n) based on the following Equation 1.
Iout (n) = Iout (n-1)
+ Kp × (E (n) −E (n−1)) + Ki × E (n)...
6. The gain changing means (170) according to any one of claims 1 to 5, wherein the first and second coefficients change at least one of Kp and Ki as the control gain. Air conditioner.   When the first constant is a1, the second constant is a2, the variable is α, and Kp = a1 × α and Ki = a2 × α are established, the gain changing means (170) sets the variable α to The air conditioner according to claim 6, wherein the first and second coefficients are changed as the control gain by changing the first and second coefficients. The current command value is Iout (n), the previous command value is Iout (n−1),
The current temperature deviation is E (n), the previous temperature deviation is E (n-1), the previous temperature deviation is E (n-2), the first coefficient is Kp, and the second coefficient is Ki. When the third coefficient is Kd, the calculation means repeatedly calculates the command value Iout (n) based on the following formula 2.
Iout (n) = Iout (n−1) + Kp × (E (n) −E (n−1))
+ Ki × E (n)
+ Kd * ((E (n) -E (n-1))-(E (n-1) -E (n-2))) Equation 2
6. The gain changing means (170) according to any one of claims 1 to 5, wherein at least one of the first, second, and third coefficients is changed as the control gain. Air conditioner.   When the first constant is a1, the second constant is a2, the third constant is a3, the variable is α, and Kp = a1 × α, Ki = a2 × α, and Kd = a3 × α are satisfied, The gain changing means (170) changes each of the first, second, and third coefficients Kp, Ki, and Kd as the control gain by changing the variable α. 8. The air conditioner according to 8.

Images