JP2003278660A - Drive torque calculation device for variable displacement compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive torque calculation device for variable displacement compressor capable of calculating drive torque of a compressor with a high presumed accuracy in consideration of refrigerant flow rate flowing in an evaporator of a refrigeration cycle. <P>SOLUTION: An external control type compressor 3 is provided on the refrigeration cycle of an air conditioning device for a vehicle and can control the theoretical discharge capacity per unit of time by the signal from the outside arbitrarily. The refrigerant flow rate Gr flowing in the evaporator 7 is presumed based on the change of enthalpy before and after the evaporator provided on the low-pressure side of the refrigeration cycle and the compressor drive torque calculation part 20a calculating the compressor drive torque Tcomp using the presumed refrigerant flow rate Gr is provided on the air conditioning control unit 20. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a drive torque calculation device for a variable capacity compressor used in a refrigeration cycle of an air conditioner mounted on an automobile.

[0002]

2. Description of the Related Art Conventionally, as a drive torque calculation device for a variable displacement compressor, for example, one disclosed in Japanese Patent Laid-Open No. 5-99156 is known.

In this prior art publication, the capacity in the variable region of the variable capacity compressor is calculated based on the outside air temperature, the rotational speed, the high pressure side pressure and the vehicle speed, and the variable range is calculated using the calculated capacity and the high pressure side pressure. And the drive torque after reaching the maximum capacity by using the maximum capacity and the high-pressure side pressure. Then, a device that determines the smaller one of the calculated driving torques as the final driving torque is described.

[0004]

However, in the drive torque calculation device for a conventional variable displacement compressor, the compressor drive torque is estimated mainly on the high pressure side from the high pressure side (condenser side) in the refrigeration cycle. Therefore, the information on the low pressure side (evaporator side) is lacking in the refrigeration cycle, and since the refrigerant flow rate that is important for estimating the compressor drive torque is not considered at all, it is calculated. There is also a problem that the compressor drive torque becomes information with low estimation accuracy.

The present invention has been made in view of the above problems, and a variable capacity compressor capable of calculating the compressor drive torque with high estimation accuracy by considering the flow rate of the refrigerant flowing through the evaporator of the refrigeration cycle. An object is to provide a drive torque calculation device.

[0006]

In order to achieve the above object, according to the present invention, a theoretical discharge capacity per unit time is arbitrarily provided by a signal from the outside provided in a refrigeration cycle of a vehicle air conditioner. In a variable capacity compressor capable of, the compressor drive torque that estimates the refrigerant flow rate through the evaporator based on the change in enthalpy before and after the evaporator that is installed on the low pressure side of the refrigeration cycle, and calculates the compressor drive torque using the estimated refrigerant flow rate. A calculation means was provided.

[0007]

In the drive torque calculating apparatus for a variable capacity compressor of the present invention, the refrigerant flow rate flowing through the evaporator is estimated, and the compressor drive torque is calculated using the estimated refrigerant flow rate. The compressor drive torque can be calculated with high estimation accuracy that takes into consideration.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment for realizing a drive torque calculating device for a variable displacement compressor according to the present invention will be described below as a first embodiment corresponding to the invention according to claims 1, 2, 3, 4, 5, and 6.
A description will be given based on examples.

(First Embodiment) First, the structure will be described. FIG. 1 is a diagram of an air conditioning system for a vehicle to which the drive torque calculating device for a variable displacement compressor according to the first embodiment is applied. Figure 1
In the figure, 1 is an engine, 2 is a radiator, 3 is an external control type compressor (variable capacity compressor), 4 is a condenser, 5 is a liquid tank, 6 is a temperature type automatic expansion valve,
7 is an evaporator, 8 is an alternator, 9 is a cooling electric fan, 10 is a fan motor, 11 is a control valve, 12 is a blower fan, 13 is a blower fan motor,
Reference numeral 14 is a fuel injector.

The engine 1 has a fuel injector 14 for injecting fuel, and the engine 1 and the radiator 2 are connected by an engine cooling water inlet pipe and an engine cooling water outlet pipe.

The air conditioner cycle in the first embodiment is composed of an external control type compressor 3, a condenser 4, a liquid tank 5, a temperature type automatic expansion valve 6 and an evaporator 7. Hereinafter, each component will be described.

The external control type compressor 3 is driven by the engine 1 and converts the low temperature low pressure gas refrigerant sent from the evaporator 7 into high pressure high temperature gas and sends it to the condenser 4. In this external control type compressor 3, the compressor capacity is variably controlled from the outside by a duty signal to the control valve 11 incorporated therein. The detailed structure of the external control type compressor 3 will be described later.

The condenser 4 is arranged in front of the radiator 2 and is cooled by a traveling wind or a wind obtained by a cooling electric fan 9 to cool a high-pressure and high-temperature refrigerant to a condensation point to form a high-pressure and medium-temperature liquid and send it to a liquid tank 5. .

The liquid tank 5 removes water and dust contained in the refrigerant due to the high-pressure and medium-temperature liquid sent from the condenser 4, stores it so that the refrigerant can be smoothly supplied, and sends it to the temperature type automatic expansion valve 6.

The temperature type automatic expansion valve 6 rapidly expands the refrigerant sent from the liquid tank 5 by the high-pressure medium-temperature liquid to form a low-temperature low-pressure liquid (fog), and the evaporator 7
Send to.

The evaporator 7 evaporates the mist-like refrigerant sent from the temperature type automatic expansion valve 6 while removing heat from the air inside the vehicle sent by the blower fan 12 to form a low-pressure low-temperature gas. The refrigerant of the above gas is sent to the external control type compressor 3.

The cooling electric fan 9 is connected to the engine 1
The fan motor 10 is operated by using the terminal voltage of the alternator 8 driven by the power source. In this fan motor 10, the motor drive voltage is PWM controlled (PWM = Pu
lse Width Modulation), and the fan motor 10
The cooling capacity of the condenser is controlled variably by the operation of.

The blower fan 12 is driven by a blower fan motor 13, sucks in air, which is the air in the vehicle compartment, sends it by pressure to the evaporator 7, and sends out the cooled air into the vehicle compartment.

Next, the electronic control system will be described. Figure 1
20, an air conditioning control unit, 20a a compressor drive torque calculation unit (compressor drive torque calculation means), 20b a fan motor control unit, 20c a compressor capacity control unit, 21 an air conditioning control input sensor system, 22 a PWM module, Reference numeral 23 is an engine control unit, and 24 is an engine control input sensor system.

The air conditioning control unit 20 includes a compressor drive torque calculating section 20a for calculating the compressor drive torque Tcomp based on the refrigerant flow rate Gr on the low pressure side (evaporator 7) of the refrigeration cycle, and a duty signal output to the PWM module 22. A fan motor control unit 20b that calculates the duty ratio, a COMP capacity control unit 20c that calculates the duty signal output to the control valve 11,
Have.

As the air conditioning control input sensor system 21, an air conditioner switch 21-1, a mode switch 21-2, a differential switch 21-3, an auto switch 21-4, an FRE switch 21-5, R
EC switch 21-6, temperature adjustment switch 21-7, off switch 21-8, inside air temperature sensor 21-9 (pre-evaporator temperature detection means in inside air circulation mode), outside air temperature sensor 21-10 (in outside air introduction mode) A pre-evaporation temperature detection means), a solar radiation sensor 21-11, a suction temperature sensor 21-12 (post-evaporation temperature detection means), a water temperature sensor 21-13, a refrigerant pressure sensor 21-14 (high pressure refrigerant pressure detection means) are provided. There is.

These existing air conditioning control input sensor system 21
In addition, a pre-evaporation humidity sensor 21-15 (pre-evaporation humidity detecting means) for detecting the inlet humidity of the evaporator 7 is added.

The engine control unit 23
Is an air conditioning control unit 20 via both communication lines.
A vehicle speed sensor 24-1, an engine speed sensor 24-2, an accelerator opening sensor 24-3, an idle switch 24-4, etc. are provided as the engine control input sensor system 24.

FIG. 2 is a sectional view showing the external control type compressor 3, and FIG. 3 is an explanatory view of the control operation of the compressor capacity (discharge side pressure) by the duty signal to the control valve 11 of the external control type compressor 3.

The external control type compressor 3 is of a multi-cylinder swash plate type and includes a compressor case 30 and a pulley 31.
A drive shaft 32, a swash plate driving body 33, a swash plate 34, a piston 35, a high pressure ball valve 36, a control valve 11, a high pressure chamber 37, and a crank chamber 38. ing.

The external control type compressor 3 controls the discharge capacity by changing the inclination of the built-in swash plate 34. That is, the lift amount of the high pressure ball valve 36 is changed by the duty signal to the control valve 11 incorporated in the external control type compressor 3. Thereby, the flow rate of the refrigerant flowing from the high pressure chamber 37 (= the discharge side pressure Pd) to the crank chamber 38 through the high pressure ball valve 36 is controlled, and the pressure of the crank chamber 38 in the compressor 3 (= the crank chamber pressure Pc) is controlled. The inclination of the swash plate 34 is changed.

As shown in FIG. 3, the lift amount of the high pressure ball valve 36 is a balance between the low pressure (= suction side pressure Ps) of the diaphragm of the control valve 11, the spring load of the set spring and the magnetic force generated in the electromagnetic coil. Determined by

The electromagnetic coil in the control valve 11 is connected to the electromagnetic coil from the compressor capacity controller 20c, for example,
A 400 Hz pulse ON-OFF signal (duty signal) is sent, and the lift amount of the high pressure ball valve 36 is controlled by the change in the magnetic force generated by the effective current due to the duty ratio.

Next, the operation will be described.

FIG. 4 shows the air conditioner control unit 20.
3 is a flowchart showing the flow of a driving torque calculation process executed by the compressor driving torque calculation unit 20a of FIG. 1, and the driving torque calculation operation of the external control type compressor 3 will be described along this flowchart.

The drive torque calculation process may be always executed during the operation of the cooler, or may be executed by a request from the engine control unit 23 during deceleration fuel cut control, idle speed control, or the like. You can

[Calculation of Indoor Air Volume (Volume Flow Rate)] First, in step S1, the intake port switch (FRE switch 21-5).
And a signal from the REC switch 21-6), it is determined whether the intake door provided in the intake duct of the blower fan 12 is at the outside air introduction position or the inside air circulation position. If the inside air circulation position is reached, the process proceeds to step S2.

If it is the outside air introduction mode, step S2
In step S3, the outside air temperature sensor recognition value obtained by delay-correcting the temperature detected by the outside air temperature sensor 21-10 is input.
In, the blower fan motor drive signal (duty ratio) to the blower fan motor 13 is delayed and the blower fan rotation speed recognition value is input, and in step S4, the signals from the mode switch 21-2 and the differential switch 21-3 are input. Input the air conditioning mode determined based on this. In the next step S5, the indoor air volume Ga is calculated based on the input information in the outdoor air introduction mode (indoor air volume calculation unit).

On the other hand, in the inside air circulation mode, the inside air temperature sensor recognition value obtained by delay-correcting the temperature detected by the inside air temperature sensor 21-9 is input in step S6, and the blower fan to the blower fan motor 13 is input in step S7. The blower fan rotation speed recognition value obtained by delay-correcting the motor drive signal (duty ratio) is input, and in step S8, the air conditioning mode determined based on the signals from the mode switch 21-2 and the differential switch 21-3 is input. . In the next step S9, the indoor air volume Ga is calculated based on the input information in the indoor air circulation mode (indoor air volume calculation unit).

As described above, the indoor air flow rate Ga flowing into the vehicle compartment through the evaporator 7 is a condition such as a blower fan rotation speed for each air conditioning mode in the outside air introduction mode or each air conditioning mode in the inside air circulation mode. If experiments are performed while changing the settings and a map (calculation formula, table, etc.) is set based on the measured data, it is possible to calculate accurately using the input information and the map. Then, when the indoor air volume Ga is calculated in step S4 or step S8, the process proceeds to step S10.

[Calculation of Evaporator Air Heat Absorption] First,
In step S10, the pre-evaporation humidity sensor recognition value obtained by delay-correcting the detected humidity by the pre-evaporation humidity sensor 21-15 is input. In step S11, the post-evaporation temperature sensor recognition obtained by delay-correcting the detected temperature by the suction temperature sensor 21-12 A value is input and the process proceeds to step S12.

In the next step S12, the evaporator air heat absorption amount Qevap (air) is calculated by the following equation using the air enthalpy difference (ia1-ia2) before and after the evaporator and the volume flow Ga 'of dry air (evaporator air). Endotherm calculation unit). Qevap (air) = (ia1−ia2) × Ga ′ ... (1) where ia1 is the inlet air enthalpy of the evaporator, ia2 is the outlet air enthalpy of the evaporator, Ga ′ is the volumetric flow rate of dry air, and G ′ is
a '= Ga / vi (vi: specific inlet air volume).

In order to obtain the inlet air enthalpy ia1, it is necessary to measure the inlet temperature t1 and the inlet humidity ψ1 as shown in FIG. On the other hand, the air inlet side temperature t1 is an outside air temperature sensor recognition value in the outside air introduction mode, and is an inside air temperature sensor recognition value in the inside air circulation mode. The inlet inlet humidity ψ1 is a pre-evaporation humidity sensor recognition value. Therefore, the air inlet air enthalpy ia1 can be obtained from these recognized values.

To obtain the outlet air enthalpy ia2, it is necessary to measure the outlet temperature t2 and the outlet humidity ψ2 as shown in FIG. On the other hand, the temperature t2 at the outlet side of the evaporator is a post-evaporation temperature sensor recognition value. Also, the humidity at the outlet side ψ2 may be set at about 95% according to the experimental results. Therefore, the air outlet outlet air enthalpy ia2 can be obtained from the post-evaporator temperature sensor recognition value and the air outlet outlet side humidity set value.

Since the indoor air volume Ga indicates the volumetric flow rate of moist air, it must be converted into the volumetric flow rate Ga '(= Ga / vi) of dry air. Therefore, the air inlet specific air volume vi is used, but in order to obtain the air inlet specific air volume vi, the air inlet side temperature t1 and the air inlet side humidity ψ1 need to be measured as shown in FIG. On the other hand, the temperature t1 at the inlet side of the evaporator is
In the outside air introduction mode, it is the outside air temperature sensor recognition value, and in the inside air circulation mode, it is the inside air temperature sensor recognition value. The inlet inlet humidity ψ1 is a pre-evaporation humidity sensor recognition value. Therefore, the volumetric flow rate Ga 'of dry air can be obtained from these recognized values.

In this way, the air volume Ga in the passenger compartment, the temperature t1 on the inlet side of the air inlet on the basis of the recognition value of the outside air temperature sensor or the recognition value of the inside air temperature sensor, the humidity on the inlet side ψ1 on the basis of the recognition value of the pre-evaporation humidity sensor, and the post-evaporation temperature sensor. Evaporator outlet side temperature t2 based on the recognized value and evaporator outlet side humidity ψ based on the experimentally set value
Using 2 and 2, the evaporator air heat absorption amount Qevap (air) can be calculated accurately. Then, step S12
When the evaporator air heat absorption amount Qevap (air) is calculated at step S13, the process proceeds to step S13.

[Calculation of Evaporator Refrigerant Endotherm] Since the Mollier diagram shown in FIG. 6 shows the state per unit weight of refrigerant, the actual amount of evaporator refrigerant endotherm Qevap (refrigerant) can be calculated. It is necessary that the refrigerant is circulating. Assuming that amount to be the refrigerant flow rate Gr, the evaporator refrigerant endothermic amount Qevap (refrigerant) corresponds to a change in the enthalpy of the refrigerant as the evaporator 7 takes heat from the outside.

Therefore, in step S13, the evaporator refrigerant endothermic amount Qevap (refrigerant) is calculated by the following equation using the refrigerant enthalpy difference (ievap1-ievap2) before and after the evaporator and the refrigerant flow amount Gr. Qevap (refrigerant) = (ievap1−ievap2) × Gr (2) Here, ievap1 is the evaporator inlet refrigerant enthalpy, ievap2 is the evaporator outlet refrigerant enthalpy, and Gr is the refrigerant flow rate.

The evaporator inlet refrigerant enthalpy ievap1 is the same as the refrigerant enthalpy on the upstream side of the high temperature side automatic expansion valve 6 (line cd in FIG. 6), and this high pressure refrigerant enthalpy is the high pressure side liquid tank. 5 Refrigerant pressure sensor recognition value by the refrigerant pressure sensor 21-14 set at the outlet side of 5 and the subcool that can be taken at that time (supercooling, that is, cooling the liquid refrigerant after it has exited the liquid tank again in the subcool section of the condenser) It is uniquely determined by and. Regarding subcooling, when a condenser and liquid tank, which are the mainstream these days, are integrated and a subcooler condenser that uses a subcooler cycle is adopted, there is a nearly proportional relationship between the outside air temperature and the vehicle speed.For example, the vehicle speed in the idling range is constant. If given, it will be a function of the outside temperature.

The best way to obtain the evaporator outlet refrigerant enthalpy ievap2 is by detecting the outlet pressure of the evaporator 7. Here, the evaporator efficiency ηev shown below is used.
Calculate the outlet pressure of the evaporator based on the formula of ap. ηevap = (ia1−ia2) / (ia1−i (Tevap)) (3) where i (Tevap) is the air outlet air enthalpy at the saturated refrigerant temperature Tevap at the air outlet.

That is, looking at the actual refrigeration cycle,
There is a pressure drop because the evaporator and condenser pressures are not constant and there is refrigerant flow. The same applies to the piping section. Further, the compressor is very complicated in that it has pressure loss due to suction and discharge, heat is added to the refrigerant due to mechanical friction, and internal leakage exists.
This behavior is shown in the Mollier diagram as shown in FIG. ,: The enthalpy of the evaporator / condenser increases / decreases with a pressure drop due to the flow of the refrigerant. ,: The enthalpy is constant because the pressure drop through the pipe does not transfer heat. : The compression of the compressor is not constant in entropy,
The entropy increases by the amount of heat generated by the loss and tilts to the right of the isentropic line. Due to the loss of ~, the actual evaporator efficiency ηev
ap is lower than in the ideal case.

Therefore, if the evaporator efficiency ηevap is experimentally acquired, the evaporator outlet air enthalpy i (Tevap) at the saturated refrigerant temperature Tevap at the evaporator outlet is obtained, and the evaporator outlet pressure Pevap is calculated from the result.

By the way, although the evaporator efficiency ηevap is to be obtained by an experiment, there is no big difference in practice, and it is known that, for example, as shown in FIG. 8, it shows a substantially constant value depending on the size and type of the evaporator. There is no need to obtain a detailed map for each vehicle type.

Thus, in the above equation (2), the evaporator inlet refrigerant enthalpy ievap1 and the evaporator outlet refrigerant enthalpy ie
The evaporator refrigerant endothermic amount Qevap (refrigerant) can be calculated with vap2 being a known value and the refrigerant flow rate Gr being an unknown value. Then, when the evaporator refrigerant heat absorption amount Qevap (refrigerant) is calculated in step S13, the process proceeds to step S14.

[Calculation of Refrigerant Flow Rate] Evaporator air endotherm Qevap (air) and evaporator refrigerant endotherm Qeva
With p (refrigerant), there is a relation of Qevap (air) = Qevap (refrigerant). Therefore, in step S14, the refrigerant flow rate Gr is calculated by the following formula (refrigerant flow rate calculation unit). Gr = Qevap (air) / (ievap1−ievap2) (4) When the refrigerant flow rate Gr is calculated in step S14, the process proceeds to step S15.

[Calculation of Compressor Suction Side Pressure] In step S15, the outlet air pressure Pe obtained in step S13 is calculated.
The compressor suction side pressure Ps is calculated by the following equation using vap and the pressure loss ΔP (low) due to the piping from the evaporator 7 to the external control type compressor 3. Ps = Pevap−ΔP (low) (5) Here, the pressure loss ΔP (low) has a relationship as shown in FIG. 9 with respect to the refrigerant flow rate Gr, and this refrigerant flow rate Gr was used. It is calculated by the following formula. ΔP (low) = k × Gr ^m (6) Here, k and m are coefficients, which can be obtained by performing bench tests on the piping layout of each vehicle.

[Calculation of Compressor Discharge Side Pressure] In the next step S16, the compressor discharge side pressure Pd is calculated by the following equation using the condenser outlet pressure Pcondout and the pressure loss ΔP (cond). Pd = Pcondout + ΔP (cond) (7) Since the refrigerant pressure sensor 21-14 is provided at the outlet of the high-pressure side liquid tank 5, the refrigerant pressure sensor recognition value is the condenser outlet pressure Pcondout. Can be
Further, the pressure loss ΔP (cond) in the condenser 4 is expressed by the following equation using the refrigerant flow rate Gr. ΔP (cond) = k × Gr ⁿ (8) Here, k and n are coefficients, which can be obtained by performing bench experiments using the applied capacitors.

[Calculation of Compressor Suction Volume] Next, the compressor suction volume Vcomp can be calculated by the following theoretical formula using the compressor cylinder volume V1, the compressor rotation speed Ncomp, and the volume efficiency ηv. Vcomp = (60 · V1 · Ncomp · ηv) / 10 ⁶ (9) Here, the compressor cylinder volume V1 is a value determined by the type of the compressor to be applied. The compressor rotation speed Ncomp is Ncomp = engine rotation speed when the engine is driven, and is the motor rotation speed when the electric motor is driven. The volume efficiency ηv can be obtained by conducting an experiment in advance.

However, it has been found that the actual compressor suction volume Vcomp is better matched by converting it according to the following relationship using the refrigerant flow rate Gr instead of the theoretical formula.
Therefore, in step S17, the compressor suction volume Vcomp is obtained from the following relationship. Vcomp∝k · Gr (10) Here, k is a constant and is set by experimental data.

[Calculation of Compressor Driving Torque] In step S18, the compressor suction side pressure Ps, the compressor discharge side pressure Pd, the compressor suction volume Vcomp,
Using the adiabatic coefficient k, and the compressor drive torque Tcomp
Is calculated by the following formula (compressor drive torque calculation unit). Tcomp = k / (k-1) .Ps.Vcomp. {(Pd / Ps) ^{(K-1) / k-} 1} (11) In addition, it is surrounded by the P-V diagram shown in FIG. Area (11)
It is a theoretical value of the compressor drive torque Tcomp obtained by the equation. However, compared with the theoretical value of compressor drive torque Tcomp (area surrounded by 1,2,3,4), actual compressor drive torque Tcomp (area surrounded by 1 ', 2', 3 ', 4')
Increases with the addition of each loss in the figure. Therefore,
The compressor driving torque Tcomp obtained by the equation (11) may be corrected in consideration of the compressor efficiency ηcomp, and the corrected value may be obtained as the final compressor driving torque Tcomp.

[Use of Compressor Drive Torque Information] In step S19, the compressor drive torque Tcomp calculated in step S18 is transmitted to the engine control unit 23 and the compressor capacity control section 20c.

By transmitting this to the engine control unit 23, the compressor load can be accurately grasped on the engine control side. For example, the compressor drive torque can be used for various engine controls such as deceleration fuel cut control and idle speed control. Information can be utilized. In other words, on the engine control side, the threshold value and target value used for control were set assuming the maximum compressor drive torque so that engine stall does not occur, whereas these values are set in the compressor drive torque information. It can be given as a value.

Further, by transmission to the compressor capacity control unit 20c, for example, when fuel cut control during deceleration or idle speed control is performed, the compressor capacity is lowered on the air conditioning control side if the required cooling capacity is low. It is also possible to perform comprehensive control by coordinating air conditioning control and engine control.

Next, the effect will be described.

In the drive torque calculating apparatus for the variable displacement compressor of the first embodiment, the effects listed below can be obtained.

(1) In the external control type compressor 3 provided in the refrigeration cycle of the vehicle air conditioner and capable of arbitrarily controlling the theoretical discharge capacity per unit time by a signal from the outside, the low pressure side of the refrigeration cycle Based on the change in enthalpy before and after the evaporator provided, the compressor drive torque calculation unit 20a that estimates the refrigerant flow rate Gr flowing through the evaporator 7 and calculates the compressor drive torque Tcomp using the estimated refrigerant flow rate Gr is installed in the air conditioning control unit 20. The compressor drive torque Tcomp can be calculated with high estimation accuracy in consideration of the refrigerant flow rate Gr flowing through the evaporator 7 of the refrigeration cycle.

(2) Compressor drive torque calculation section 20a
Is an indoor air volume calculation step (steps S1 to S9) for calculating an indoor air volume Ga flowing into the vehicle compartment after passing through the evaporator 7 provided in the refrigeration cycle, and an indoor air volume Ga
And an evaporator air heat absorption amount calculation step (step S12) for calculating an evaporator air heat absorption amount Qevap (air) based on a change in air enthalpy before and after the evaporator, and a calculated evaporator air heat absorption amount Qevap (air) and a refrigerant before and after the evaporator. Enthalpy change of (ievap1−ie
vap2) is used to calculate the refrigerant flow rate Gr flowing through the evaporator 7 (step S14), and the calculated refrigerant flow rate Gr is used to calculate the compressor drive torque Tco.
Since the compressor drive torque calculation step (step S18) of calculating mp is included, the refrigerant flow rate Gr flowing through the evaporator 7 of the refrigeration cycle, which influences the estimation accuracy of the compressor drive torque Tcomp, can be calculated by using the evaporator air heat absorption amount Qevap (air). By calculation, it can be estimated with high accuracy.

(3) Indoor air volume calculation step (step S1
Step S9) is a calculation element of the evaporator air heat absorption amount Qevap (air) for dividing into the outside air introduction mode and the inside air circulation mode, and calculating the indoor air amount Ga according to the blower fan speed and the air conditioning mode for each mode. Indoor air flow Ga
Can be accurately estimated regardless of the outside air introduction mode or the inside air circulation mode.

(4) A pre-evaporation humidity sensor 21-15 for detecting the inlet humidity ψ1 of the evaporator 7 is added, and the evaporator air heat absorption amount calculating step (step S12) is performed by the evaporator temperature τ1 and the inlet humidity ψ1. The inlet air enthalpy ia1 is obtained, the outlet air enthalpy ia2 is obtained from the outlet temperature t2 and the outlet humidity ψ2 of the evaporator 7, and the outlet air enthalpy ia2 is subtracted from the inlet air enthalpy ia1 to obtain the air enthalpy difference (ia1−ia2).
The calculated indoor air volume Ga and the air enthalpy difference
(ia1-ia2) and the evaporator air heat absorption Qevap
(air) is calculated by calculating the difference between the indoor air volume Ga and the air enthalpy.
Accurate evaporator air heat absorption Q by (ia1-ia2)
evap (air) can be calculated.

In addition, in the first embodiment, the evaporator 7
Of the inlet temperature t1 of the evaporator 7 is detected using the existing inside air temperature sensor 21-9 or the outside air temperature sensor 21-10, and the outlet temperature t2 of the evaporator 7 is detected using the existing suction temperature sensor 21-12.
Since the outlet humidity ψ2 of the evaporator 7 is a fixed value because it is a constant value without needing to be measured, the pre-evaporation humidity sensor 21- that detects the inlet humidity ψ1 of the evaporator 7
With the system in which only 15 is added, the evaporator air heat absorption amount Qevap (air) can be calculated accurately while suppressing the cost increase.

(5) Refrigerant flow rate calculation step (step S1
4) is to obtain the evaporator inlet refrigerant enthalpy ievap1 based on the refrigerant pressure detection value from the refrigerant pressure sensor 21-14 and the evaporator outlet refrigerant enthalpy ievap2 based on the evaporator efficiency ηevap. Refrigerant enthalpy difference (ievap1-ievap2) is obtained by subtracting enthalpy ievap2, and the evaporator air heat absorption amount Qevap (air) and refrigerant enthalpy difference (ievap1-i)
evap2) and the refrigerant flow rate Gr flowing through the evaporator 7
Evaporator air heat absorption Qevap (air)
And the refrigerant enthalpy difference (ievap1-ievap2), the refrigerant flow rate Gr flowing through the evaporator 7 can be calculated accurately.

[0067] and (6) a compressor drive torque calculating step (step S18), the pressure loss due to pipe from the evaporator outlet pressure Pevap and the evaporator 7 to the external control type compressor 3 △ P (low) (= k × Gr m) Determine the compressor suction side pressure Ps using the condenser outlet pressure Pcondout
And obtains the compressor discharge side pressure Pd by using the pressure loss △ P (cond) (= k × Gr n), obtains the compressor suction volume Vcomp using refrigerant flow rate Gr, the compressor suction side pressure Ps was sought and the compressor Since the compressor drive torque Tcomp is calculated using the suction side pressure Pd, the compressor suction volume Vcomp, and the adiabatic coefficient k, three torque calculation elements of the compressor suction side pressure Ps, the compressor suction side pressure Pd, and the compressor suction volume Vcomp are used as the refrigerant. The compressor drive torque T can be calculated with high accuracy by obtaining it based on the flow rate Gr.
comp can be calculated.

The drive torque calculating device for a variable displacement compressor according to the present invention has been described above based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the present invention is not limited thereto. Modifications and additions of the design are allowed without departing from the scope of the invention according to each claim of the scope.

For example, in the first embodiment, an example in which an external control type compressor driven by an engine is used as the compressor has been shown, but the present invention can be applied to a refrigeration cycle equipped with a variable displacement electric compressor driven by a motor.

In the first embodiment, the preferable example in which the pre-evaporation humidity sensor is simply added as a sensor is shown. However, even if sensors other than the pre-evaporation humidity sensor are added,
In short, based on the change in the enthalpy before and after the evaporator provided on the low pressure side of the refrigeration cycle, the refrigerant flow rate flowing through the evaporator is estimated, and if the compressor drive torque is calculated using the estimated refrigerant flow rate, the present invention is applicable. included.

[Brief description of drawings]

FIG. 1 is a vehicle air conditioning system diagram to which a drive torque calculation device for a variable displacement compressor according to a first embodiment is applied.

FIG. 2 is a cross-sectional view showing an external control type compressor included in a refrigeration cycle to which the device of the first embodiment is applied.

FIG. 3 is an explanatory view of a variable capacity control operation in an external control type compressor included in the refrigeration cycle applied to the device of the first embodiment.

FIG. 4 is a flowchart showing a flow of a drive torque calculation process executed by a compressor drive torque calculation unit of the air conditioner control unit of the first embodiment.

FIG. 5 is a diagram showing the relationship between the evaporator inlet air enthalpy and the evaporator outlet air enthalpy at the front and rear positions of the evaporator.

FIG. 6 is a Mollier diagram showing an ideal refrigeration cycle.

FIG. 7 is a Mollier diagram showing an actual refrigeration cycle.

FIG. 8 is an evaporator efficiency characteristic diagram with respect to the amount of heat absorbed by the evaporator.

FIG. 9 is a pressure loss characteristic diagram with respect to a refrigerant flow rate.

FIG. 10 is a diagram showing an actual compression diagram with respect to an ideal compression diagram in a reciprocating compressor.

[Explanation of symbols]

1 Engine 2 Radiator 3 Externally Controlled Compressor (Variable Capacity Compressor) 4 Condenser 5 Liquid Tank 6 Temperature Automatic Expansion Valve 7 Evaporator 8 Alternator 9 Cooling Electric Fan 10 Fan Motor 11 Control Valve 12 Blower Fan 13 Blower Fan Motor 14 Fuel Injector 20 Air-conditioning control unit 20a Compressor drive torque calculation section (compressor drive torque calculation means) 20b Fan motor control section 20c Compressor capacity control section 21 Air-conditioning control input sensor system 21-9 Inside air temperature sensor (pre-evaporator temperature detection means in inside air circulation mode) 21-10 Outside air temperature sensor (pre-evaporator temperature detection means in outside air introduction mode) 21-12 Suction temperature sensor (post-evaporator temperature detection means) 21-14 Refrigerant pressure sensor (high pressure refrigerant pressure detection means) 21-15 Evaporator pre-humidity Sen (Eva before humidity detecting means) 22 PWM module 23 engine control unit 24 engine control input sensor system

Continued front page    F term (reference) 3G093 AA13 DA01 DA06 DB00 DB05                       DB07 DB09 DB25 EB05                 3H045 AA04 AA10 AA12 AA27 BA01                       CA02 CA03 CA09 CA13 CA24                       CA28 DA00 DA09 DA43 EA13                       EA16 EA17 EA26 EA38 EA42                       EA46

Claims (6)

[Claims] 1. A variable capacity compressor provided in a refrigeration cycle of a vehicle air conditioner and capable of arbitrarily controlling a theoretical discharge capacity per unit time by a signal from the outside, and an evaporator provided on a low pressure side of the refrigeration cycle. Drive of a variable capacity compressor characterized in that a compressor drive torque calculating means for estimating a refrigerant flow rate flowing through an evaporator based on a change in enthalpy before and after and calculating a compressor drive torque using the estimated refrigerant flow rate is provided. Torque calculation device. 2. The drive torque calculation device for a variable capacity compressor according to claim 1, wherein the compressor drive torque calculation means calculates an amount of indoor air flowing into a vehicle after passing through an evaporator provided in a refrigeration cycle. An air flow amount calculation unit, an evaporator air heat absorption amount calculation unit that calculates an evaporator air heat absorption amount based on a change in the indoor air flow amount and an air enthalpy before and after the evaporator, and a calculated evaporator air heat absorption amount and a change in the refrigerant enthalpy before and after the evaporator. A drive torque calculation device for a variable capacity compressor, comprising: a refrigerant flow rate calculation unit that calculates the flow rate of the refrigerant flowing through the evaporator; and a compressor drive torque calculation unit that calculates the compressor drive torque using the calculated refrigerant flow rate. . 3. The drive torque calculation device for a variable displacement compressor according to claim 2, wherein the indoor air volume calculation unit is divided into an outside air introduction mode and an inside air circulation mode, and a blower fan rotation speed and an air conditioning mode are set for each mode. A drive torque calculation device for a variable displacement compressor, which calculates the indoor air volume according to the above. 4. The drive torque calculation device for a variable displacement compressor according to claim 2, wherein the pre-evaporator temperature detecting means for detecting the inlet temperature of the evaporator and the inlet humidity of the evaporator are detected. A pre-evaporation humidity detection means, an after-evaporation temperature detection means for detecting the outlet temperature of the evaporator, and an after-evaporation humidity detection means for detecting the outlet humidity of the evaporator are provided, and the evaporator air endothermic calorific value calculation unit is provided at the evaporator inlet temperature. And the inlet humidity to determine the inlet air enthalpy, the evaporator outlet temperature and outlet humidity to determine the outlet outlet air enthalpy, subtract the outlet outlet air enthalpy from the outlet inlet air enthalpy to obtain the air enthalpy difference, and calculate the indoor air volume Using the indoor air volume calculated by the above and the air enthalpy difference, Driving torque calculating device of the variable displacement compressor and calculates the porator air heat absorption amount. 5. The drive torque calculation device for a variable displacement compressor according to claim 2, further comprising a high pressure refrigerant pressure detection means provided on a high pressure side of a refrigeration cycle, and the refrigerant flow rate calculation unit. Is an evaporator inlet refrigerant enthalpy based on the refrigerant pressure detection value, the evaporator outlet refrigerant enthalpy based on the evaporator efficiency, the refrigerant outlet enthalpy difference from the evaporator inlet refrigerant enthalpy to determine the refrigerant enthalpy difference, the evaporator air A drive torque calculation device for a variable capacity compressor, characterized in that a flow rate of a refrigerant flowing through an evaporator is calculated by using an evaporator air heat absorption calculated by a heat absorption calculation section and a refrigerant enthalpy difference. 6. The drive torque calculation device for a variable displacement compressor according to claim 2, wherein the low pressure refrigerant pressure detection means is provided on the low pressure side of the refrigeration cycle and the high pressure side of the refrigeration cycle. Provided with a high-pressure refrigerant pressure detection means provided, the compressor drive torque calculation unit determines the compressor suction side pressure based on the pressure loss of the pipe due to the refrigerant flow rate from the refrigerant flow rate calculation unit and the low pressure refrigerant pressure detection value, The compressor discharge side pressure is obtained based on the pressure loss of the pipe due to the refrigerant flow rate from the refrigerant flow rate calculation section and the high pressure refrigerant pressure detection value, and the compressor suction volume is obtained based on the refrigerant flow rate from the refrigerant flow rate calculation section. Compressor drive using compressor suction side pressure, compressor suction side pressure, compressor suction volume and adiabatic coefficient Driving torque calculating device for a variable displacement compressor, characterized by calculating the torque.