JP2541843B2 - Automotive air conditioner - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle air conditioner equipped with an externally controlled variable displacement compressor.

(Prior Art) An externally controlled variable displacement compressor is connected with an evaporator or the like arranged in an air conditioning duct to form a cooling cycle, and the discharge capacity can be changed by a control signal from the outside. As a control method of a cooling cycle using such a compressor, Japanese Patent Application Laid-Open No. 58-43340
According to this conventional control method, the discharge capacity of the compressor is changed stepwise according to the temperature inside the vehicle compartment or the temperature of the air taken into the air conditioning duct and the temperature immediately after the evaporator, for example. The discharge capacity of the compressor is reduced as the vehicle compartment temperature or intake air temperature is lower, and as the outlet temperature immediately after the evaporator is lower, and the compressor is turned off when the discharge temperature immediately after the evaporator falls below a specified temperature. To prevent freezing of the evaporator.

(Problems to be Solved by the Invention) However, if the above-described control is performed up to a time when maximum cooling capacity is required, such as during so-called cooldown in which the vehicle interior is rapidly cooled, the compressor becomes closer to the freezing temperature. However, the capacity is reduced and the compressor is turned off at a temperature below a predetermined temperature, so the cooling capacity is reduced and the cool down performance is deteriorated.

Therefore, in the present invention, it is an object of the present invention to provide an air conditioning system for an automobile, in which the compressor is continuously operated in a state where the maximum cooling capacity can be obtained while the maximum cooling capacity is required, and the cooldown performance is improved. I am trying.

(Means for Solving the Problem) The gist of the present invention is, as shown in FIG. 1, an evaporator 8 through which sucked air passes.
And a compressor 18 driven by an automobile engine 22
Based on at least the set temperature and the vehicle compartment temperature, a cooling cycle including the following: a mode sensor 45 that detects the degree of cooling of the evaporator 8 in this cooling cycle; a capacity varying device 37 that changes the capacity of the compressor 18 in the cooling cycle. Judgment means 11 for judging whether or not it is necessary to maximize the cooling capacity
0, when it is determined by the determination means 110 that the maximum cooling capacity is not required, the compressor 18 is stopped when the evaporator 8 is cooled to a value equal to or less than a set value that prevents the evaporator 8 from freezing, and When it is determined that the cooling capacity is necessary, the compressor on / off control means 120 for invalidating the freeze prevention function of the evaporator 8
And the evaporator 8 detected by the mode sensor 45.
Compressor so that the cooling degree of
When the discharge capacity of 18 is set and the determination means 110 determines that the maximum cooling capacity is required, the capacity setting means 130 that maximizes the set capacity, and based on the capacity set by the capacity setting means 130, Variable device control means 14 for controlling the adjustment amount of the variable capacity device 37.
It is equipped with 0 and.

(Operation) Therefore, while the maximum cooling capacity is required, the function of stopping the compressor when the evaporator temperature becomes equal to or lower than the predetermined antifreezing temperature is disabled to ensure the continuous operation of the compressor, and Since the discharge capacity of is set to the maximum, the cooling capacity can always be maximized, and therefore the above-mentioned problem can be achieved.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, the air-conditioning system for automobiles includes an air-conditioning duct 1.
An intake door switching device 2 is provided on the most upstream side of the intake door switching device 2. In the intake door switching device 2, an inside air / outside air switching door 5 is arranged at a portion where an inside air inlet 3 and an outside air inlet 4 are separated. Is operated by the actuator 6 so that the air introduced into the air conditioning duct 1 can be selected between the inside air and the outside air.

The blower 7 sucks air into the air conditioning duct 1 and blows the air downstream, and an evaporator 8 and a heater core 9 are provided behind the blower 7.

An air mix door 10 is provided in front of the heater core 9. By adjusting the opening of the air mix door 10 with an actuator 11, air passing through the heater core 9 and air bypassing the heater core 9 are provided. The ratio of is adjusted. Further, the downstream side of the heater core 9 is divided into a defrost outlet 12, a vent outlet 13 and a heat outlet 14 to open in the vehicle compartment, and mode doors 15a and 15b are provided at the divided portions.
The blowout mode can be switched by operating the actuators 16 and 17 on the actuators 5a and 15b.

The evaporator 8 constitutes a cooling cycle together with a compressor 18, a condenser 19, a liquid tank 20 and an expansion valve 21 described below. The compressor 18 is, for example, a wobble plate type, and as shown in FIG. 3, a drive shaft 24 connected to the engine 22 via an electromagnetic clutch 23 is inserted into the compressor main body 25, and the drive shaft 24 has a wobble plate. The bull plate 26 is connected via a hinge ball 27. The wobble plate 26 is supported in a crank chamber 28 formed in the compressor body 25 so as to be swingable with respect to the drive shaft 24 with a hinge ball 27 as a fulcrum, and is connected to the wobble plate 26 by a piston. 29 is reciprocated in the cylinder bore 30 according to the swing angle. Further, the compressor 18 is provided with a pressure control valve 31 so as to face the crank chamber 28, and the pressure control valve 31 is
A valve body 33 for adjusting the communication state between the crank chamber 28 and the suction chamber 32 communicating with the suction side, and the valve body depending on the pressure in the suction chamber 32.
The pressure responsive member 34 for moving the valve 33 and the valve element 33 are electromagnetic coils.
And a solenoid 36 for moving in accordance with the current amount I _SOL to 35, by controlling the current amount I _SOL to the electromagnetic coil 35 from outside, leaks into the crank chamber 28 from between the piston 29 and the cylinder bore 30 The amount of blow-by gas returning to the suction side is adjusted. Therefore, the capacity variable device that changes the capacity of the compressor 18 from the pressure control valve 31 etc.
When the solenoid 37 is configured and the amount of current I _SOL flowing through the electromagnetic coil 35 rises and the magnetic force of the solenoid 36 rises, a force is exerted on the valve body 33 in a direction to reduce the communication between the crank chamber 28 and the suction chamber 32, and the crank chamber The amount of blow-by gas leaking from 28 to the suction chamber 32 is reduced. For this reason, the pressure in the crank chamber 28 increases and the force acting on the back surface of the piston 29 increases, so that the wobble plate 26 rotates about the hinge ball 27 in the direction in which the swing angle decreases, and the piston 29 strokes, that is, the capacity of the compressor is reduced.

The variable capacity device 37 is not only a device that adjusts the amount of blow-by gas to the suction side by the pressure control valve, but also a device that changes the number of cylinders used by the compressor, and a belt transmission device that connects the compressor and the engine 22. The pulley ratio may be changed, or the number of effective vanes in the vane type compressor may be changed so long as the capacity is substantially changed.

The actuators 6, 11, 17, the motor 7a of the blower 7, the electromagnetic clutch 23 of the compressor 18 and the capacity varying device 37 are controlled based on the output signals from the microcomputer 41 via the drive circuits 40a-40f, respectively. It
The microcomputer 41 is a well-known one having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input / output port (I / O), etc., which are not shown, and the microcomputer 41 41 includes a vehicle interior temperature T _R from a vehicle interior temperature sensor 42 that detects the temperature of the vehicle interior, an outdoor air temperature T _A from an outdoor air temperature sensor 43 that detects the temperature of the outdoor air, and a solar radiation sensor 44 that detects the amount of solar radiation. Solar radiation
Q ₅ , the cooling degree T _INT from the mode sensor 45 which is provided on the evaporator 8 or on the downstream side of the evaporator 8 and detects the cooling degree of the evaporator 8 as the temperature of the evaporator 8 or the temperature of the air passing through the evaporator 8 is the multiplexer 46. Is input via the A / D converter 47 after being selected via.

Further, the output signal from the operation panel 48 is input to the microcomputer 41. The operation panel 48 includes an AUTO switch 49 for setting all of the air conditioners such as the blower to the automatic state, an OFF switch 50 for canceling the automatic control, an A / C switch 51 for manually operating the compressor 18, and an intake air inside air or Inside / outside air selector switch 52 for switching to the outside air, DEF switch 53 for setting the blowout mode to the defrost mode, temperature setter 54 for setting the set temperature inside the vehicle, speed setter 55 for setting the rotation speed of the blower, and other than the defrost mode It is equipped with a mode setting device 56 for setting the blowing mode. The temperature setter 54 comprises up / down switches 54a, 54b and a temperature display section 54c for digitally displaying the set temperature T _D, and the temperature display section 5c is operated by operating the up / down switches 54a, 54b.
The set temperature shown in 4c can be changed within a predetermined range. In addition, the speed setter 55 is the blower 7
It consists of a FAN switch 55a that switches the rotation level of the fan and a level display 55b that displays the current rotation level. The operation of the FAN switch 55a stops the rotation level of the blower 7 (level 0), LOW (level 1), MED ( Level 2), HI (level 3) and MAX HI (level 4) are sequentially switched in this order, and the letters "MANUAL" are lit on the upper part of the level display 55b. Further, the mode setter 56 sequentially switches the blowout mode in the order of vent, bilevel, and heat.
It consists of a MODE switch 56a and a picture display section 56b that shows the current blowout mode in a pictorial display.By operating the MODE switch 56a, the arrow 57a, 57b of the air flow of the picture display section 56b indicates the selected blowout mode. In addition to being illuminated, the letters "MANUAL" are illuminated at the top of the picture display portion 56b. These lighting display and the display of each display 54c, 55b, 56b is performed by the display circuit 58.
It is controlled by the microcomputer 41 via the.

In FIG. 4, a control operation example of the compressor 18 by the microcomputer 41 described above is shown as a flow chart, and the microcomputer 41 starts executing the program from step 60, and at step 62, each of the sensors 42 to 45 and the operation panel 48. Input the signal from. Then, in the next step 64, it is determined whether or not the blower 7 is driven, and in the next step 66, the A / C switch 5
It is determined whether or not 1 is pressed (ON). When the blower 7 is not rotating, the temperature control cannot be actively performed even if the compressor 18 is operated, and the A / C switch 51
If is not pressed, the occupant does not want the compressor 18 to operate, so in either case the step
Go to 68 and turn off the compressor.

On the other hand, if it is determined that the blower 7 is rotating and the A / C switch 51 is also pressed, the process proceeds to step 70, and in this step 70, for example, the target blowout temperature blown into the vehicle interior by the formula (1) is used. X _M is calculated from the set temperature T _D , the vehicle interior temperature T _R , the outside air temperature T _A , the amount of solar radiation Q _S, etc.

X _M = A · T _D + B · T _R + C · T _A + D · Q _S + E (1) where A, B, C, D, and E represent arithmetic constants.

After the target outlet temperature X _M has been calculated, the routine proceeds to step 72, where it is determined whether or not this X _M is below a predetermined value K ₁ that requires cool down control, X _M is K ₁
If it is below, the cool down control of step 74 and below is performed. That is, in step 74, the flag is set to "1" to indicate that the cool-down control is being performed, and in the next step 76, the target cooling degree of the evaporator 8
▼ is set to a predetermined temperature T ₁ which is considerably lower than the temperature at which the evaporator 8 starts freezing, such as −10 ° C. Then, in the next step 78, it is determined whether or not the target outlet temperature X _M has become equal to or higher than a predetermined value K ₂ as a result of the cool-down control. If K ₂ or more, the process proceeds to step 92 to cool. From down control to normal control described later, if it is smaller than K ₂ , the process proceeds to step 88 through steps 80 to 86, and in this step 88, the difference between the actual cooling degree T _INT of the evaporator 8 and the target cooling degree ▲ ▼ So that the relation expressed by equation (2) is established, the capacity of the compressor 18 is set and the cooling degree T _{INT of the} evaporator is set to the target cooling degree ▲
Close to ▼, After that, the process returns to step 60 via another air conditioning control routine via step 90.

Then, during the cool-down, the target cooling degree ▲ ▼ of the evaporator 8 is set considerably lower than the freezing start temperature of the evaporator 8. Therefore, even if the evaporator 8 reaches the freezing temperature, the cooling degree T _{INT of the} evaporator 8 and the target cooling degree are set. The difference with ▲ ▼ is large, and the compressor 18 continues to operate at the maximum discharge amount.

By the way, in steps 80 to 86, processing for shifting from the cool down control to the normal control is performed based on the timer. That is, in step 80, it is judged whether or not the cooling degree T _INT of the evaporator 8 is lower than a predetermined temperature T ₃ (for example, 1.5 degrees) higher than the target cooling degree ▲ ▼, and T _INT is larger than T _3. For example, the routine proceeds to step 88, and if T ₃ or less, if the timer is not operating in steps 82 and 84, time counting T by the timer is started.
Then, in the next step 86, it is determined whether or not the predetermined time t ₁ has elapsed since the timer was activated, and if not, the process proceeds to step 88, and if the predetermined time t ₁ has elapsed,
The control goes from the cool-down control to the normal control of step 92 and thereafter. As a result, if T _INT becomes the predetermined value T ₃ or less and the predetermined time t ₁ elapses from that time, the cool down control ends even if the target outlet temperature X _M is the predetermined value K ₂ or less ( (Indicated by a broken line in FIG. 5) On the contrary, if the target outlet temperature X _M is equal to or higher than the predetermined value K ₂ even before the timer times out, the comfortable temperature control state is quickly achieved by the cool-down control. The control will be shifted to the normal control earlier.

In the normal control after step 92, first, in step 92, the flag is set to "0" to indicate that the cool down control is finished, the timer is reset in step 94, and then the target cooling of the evaporator 8 is performed in step 96. Degree ▲
Predetermined temperature somewhat higher than the limit temperature for freezing ▼
Set to T ₂ (eg 3 ° C). Then, in step 98, it is determined whether the actual cooling degree T _INT of the evaporator 8 is lower than or higher than the predetermined temperatures T ₃ and T ₄ . Here, T ₃ and T ₄ are T ₃ <T ₂ <T ₄ to prevent hunting. When it is determined in this step 98 that T _INT is smaller than T ₃ , the routine proceeds to step 68, where the compressor 18 is turned off to prevent the evaporator 8 from freezing, and then step 90
This control routine is terminated via and the process returns to the main routine. When it is determined that T _INT is larger than T ₄ , the process proceeds to step 88, and the capacity of the compressor 18 is controlled so as to satisfy the relationship of the above equation (2).

In the normal control of the compressor 18, however, the target cooling degree ▲ ▼ of the evaporator 8 is set to be slightly higher than the freezing start temperature of the evaporator 8, so the compressor 18 has a reduced discharge capacity in order to prevent freezing of the evaporator 8. However, it stops before the evaporator freezes (OF
F) will be done.

In step 72, the target outlet temperature X _M is the predetermined value K ₁
If it is determined that it is larger than the above value, the process proceeds to step 100, and the flag is set to "1" to determine whether the cool down control is being performed.
It is determined by whether or not This step 10
When the cooldown control is already performed by 0, as described above, the cooldown control is performed until X _M becomes K ₂ or more or T _INT is T ₃ or less and the predetermined time t ₁ elapses. On the other hand, if the cool down control is not performed, the normal control is performed unless X _M becomes K ₁ or less, and the hunting between the cool down control and the normal control is prevented.

Next, FIG. 6 shows another embodiment of the present invention. The difference between this embodiment and the above embodiment is that the ON / OFF set value of the compressor 18 is preset in each of the cool-down control and the normal control, and the compressor 18 is controlled based on this installation value. That is what I did. Specifically, after steps 86 and 96, steps 102 and 104 for setting the ON / OFF set value of the compressor 18 as shown in FIG. 7 are provided, and in step 102, the OFF set value T _OFF of the compressor is set to the evaporator 8 the freezing limit temperature near the temperature T ₃ (e.g., 1.5 ° C.), respectively set the oN set value T _oN to the large temperature T ₄ than T _3, in step 104, from 0 ℃ the OFF set value T _OFF Even at lower temperatures T _s , O
The N set value T _ON is set to the same temperature T ₆ as T ₄ , for example. After the compressor ON / OFF set value is set in step 102 or 104, whether the actual cooling degree T _INT of the evaporator 8 is smaller or larger than the ON / OFF set value T _OFF , T _ON in step 106. Is judged, T _INT is T _OFF
If it becomes smaller, proceed to step 68 to turn off the compressor 18, and if T _INT is larger than T _ON , proceed to step 88 to control the capacity of the compressor 18 so as to satisfy the relation of the above equation (2). To do.

A portion indicated by broken lines in this Figure 7, as in the above embodiment, in step 80 through 86, the cooling of T _INT of the evaporator 8 is equal to or less than a predetermined value T _3, and from when T ₃ or less When the predetermined time t ₁ has elapsed, the target outlet temperature X _M
It shows that it shifts to the normal control even if it is smaller than K ₃ .

Even in such control, however, the OFF setting value of the compressor 18 is lowered below 0 ° C. during the cool down, so even if the evaporator 8 approaches the freezing temperature, the compressor 18 is continuously operated with the maximum discharge capacity. It can be done. Also, in this embodiment,
Since the OFF setting value of the compressor 18 is set even during cooldown, there is also a protection function that can reliably turn off the compressor 18 when, for example, air is not sucked in due to a blower failure and the evaporator's cooling level becomes abnormal. Be prepared at the same time.

Since the other steps are the same as those in the above-described embodiment, the same steps are designated by the same reference numerals and the description thereof will be omitted.

(Effects of the Invention) As described above, according to the present invention, while the maximum cooling capacity is required, the continuous operation of the compressor is guaranteed and the discharge capacity of the compressor is set to the maximum. During the cool down control, the cooling capacity can be always maintained at the maximum, and the cool down performance can be improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the present invention, and FIG. 2 is a configuration diagram showing an embodiment of an automobile air conditioner according to the present invention.
FIG. 3 is a block diagram showing an example of a compressor used in the same as above, FIG. 4 is a flow chart showing an example of control operation of the compressor by a microcomputer, and FIG. 5 is a graph showing characteristics of the target cooling degree of the evaporator in the above-mentioned operation control example. FIG. 6 is a flowchart showing another operation control example by the microcomputer, and FIG. 7 is a diagram showing characteristics of ON / OFF set values of the compressor in the control operation example of the above. 8 ... Evaporator, 18 ... Compressor, 22 ... Engine, 37 ... Variable capacity device, 45 ... Mode sensor, 10 ...
... Judgment means, 120 ... on / off control means, 130 ... capacity setting means, 140 ... variable device control means.

Claims (1)

(57) [Claims] 1. A cooling cycle including an evaporator through which sucked air passes and a compressor driven by an engine of an automobile, a mode sensor for detecting a cooling degree of the evaporator in the cooling cycle, and a compressor of the compressor in the cooling cycle. A variable capacity device for changing the capacity, a judgment means for judging whether or not the cooling capacity needs to be maximized based on at least the set temperature and the vehicle interior temperature, and the judgment means does not require the maximum cooling capacity. If it is determined, the compressor is stopped when the evaporator is cooled to a value equal to or less than the set value that prevents freezing of the evaporator, and if it is determined that the maximum cooling capacity is required, the freeze prevention function of the evaporator On / off control means for disabling the compressor and the mode sensor. The discharge capacity of the compressor is set so as to bring the degree of cooling of the evaporator close to a predetermined target value, and when the determination means determines that the maximum cooling capacity is required, the capacity setting means that maximizes the set capacity An air conditioner for an automobile, comprising: and a variable device control means for controlling an adjustment amount of the variable capacity device based on a capacity set by the capacity setting means.