JPH0277314A - Control device for on-vehicle air conditioner - Google Patents

Abstract

PURPOSE:To prevent a compressor from being unnecessarily suspended during an air conditioning operation by providing a device with a judging means which judges whether or not a compressor is in a specified condition which forces the compressor to be operated even if the cooling temperature of an evaporator is less than a specified one. CONSTITUTION:A device is provided with a freezing prevention control means 100 which suspends a compressor 18 when the cooling temperature of an evaporator 8 is less than a specified one set in advance to prevent freezing. And when the cooling temperature of the evaporator 8 is judged by a judging means to have been less than the aforesaid specified one, the freezing prevention control means 100 is disabled in function. And the device is also provided with a limiting means 300 which restores the function of the freezing prevention control means 100 starting from the time when temperature equals to or more than the specified one which can prevent the cooling temperature of the evaporator 8 from freezing, when the cooling temperature of the evaporator 8 is judged by the judging means 200 to have been out of the specified condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air conditioning control device for an automobile having a function of preventing freezing of an evaporator.

(Prior Art) In order to prevent an evaporator used in a cooling cycle from freezing, it is common practice to stop a compressor when the cooling temperature of the evaporator falls below a predetermined temperature. Even with this kind of control, when maximum cooling power is required for rapid cooling of the vehicle interior (cool down) or when improving demisting performance at low outside air temperatures (low temperature demisting), the evaporator cooling It is desirable to keep the compressor running even when the temperature falls below the freezing start temperature (around 0'C).

(Problem to be solved by the invention) However, if the anti-freeze function starts operating again immediately after cool-down control or low-temperature demist control is performed, if the evaporator cooling is still below the freezing start temperature, the compressor will stop working. It stops unnecessarily. However,
When cool-down control is performed, if the compressor is stopped due to the antifreeze function, the blowing temperature will rise rapidly, impairing comfortable temperature control. Furthermore, when low-temperature demist control was performed, there was a problem in that the window glass suddenly became foggy.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an air conditioning control device for an automobile that can eliminate the above problems, eliminate unnecessary stoppage of the compressor during air conditioning control, and perform stable air conditioning control.

(Means for Solving the Problems) The gist of the present invention is, as shown in FIG. a mode sensor 45 for detecting the cooling temperature of the evaporator 8; and a mode sensor 45 for detecting the cooling temperature of the evaporator 8; anti-freezing control means 100 for stopping the freezing, determination means 200 for determining whether or not the compressor 18 is under a predetermined environment that requires operation even if the cooling temperature of the evaporator 8 is lower than the predetermined value; When the means 200 determines that the cooling temperature of the evaporator 8 falls under the predetermined environment, the function of the antifreeze control means is disabled, and the determining means 200 determines that the cooling temperature of the evaporator 8 falls under the predetermined environment. If the cooling temperature of the evaporator 8 exceeds a predetermined temperature at which freezing can be prevented, the freezing prevention control means 1
00 function is also included.

(Function) Therefore, even if the anti-freezing function is disabled and the cooling temperature of the evaporator falls below the freezing start temperature, and the conditions for disabling the anti-freezing function are no longer met, the cooling temperature of the evaporator remains at the predetermined level that can prevent freezing. Since the anti-freezing function will not be restored unless the temperature exceeds the temperature, the compressor will not stop unnecessarily during air conditioning control, and therefore the above object can be achieved.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 2, the automobile air conditioner has air conditioning duct l-1.
An intake switching device 2 is provided on the most upstream side of the intake switching device 2, and an inside/outside air switching door 5 is disposed at the part where the inside air population 3 and the outside air population 4 are separated, and the inside/outside air switching door 5 is connected to an actuator. 6 to obtain a desired intake mode in which the air introduced into the air conditioning duct 1 can be selected between inside air and outside air.

The blower 7 sucks air into the air conditioning duct 1 and blows it downstream, and an evaporator lake 8 and a heater core 9 are provided behind the blower 7. Further, an air mix door 10 is provided in front of the heater core 9, and by adjusting the opening degree of the air mix door 10 using an actuator 11, air passing through the heater core 9 and air bypassing the heater core 9 can be controlled. As a result, the temperature of the blown air is controlled.

The downstream side of the air conditioning duct 1 is divided into a defrost outlet 12, a vent outlet 13, and a foot outlet 14, which open into the vehicle interior, and a mode door 15a is provided in the divided part.
, 15b are provided, and by operating these mode doors 15a, 15b with actuators 16 and 17, a desired blowing mode can be obtained.

The evaporator 8 constitutes a cooling cycle together with a compressor 18, a condenser 19, a liquid tank 20, and an expansion valve 21, which will be described below. The compressor 18 is, for example, of a wobble plate type, and is connected to the engine via an electromagnetic clutch 23 as shown in FIG.
A drive shaft 24 connected to the compressor 2 is inserted into the compressor body 25, and a wobble plate 26 is coupled to the drive shaft 24 via a hinge ball 27. This wobble plate 26 is attached to a drive shaft 24 with a hinge ball 27 as a fulcrum in a crank chamber 28 formed in the compressor main body 25.
The piston 29 connected to the wobble plate 26 is reciprocated within the cylinder bore 30 according to the swing angle. Further, the compressor 18 is provided with a pressure control valve 31 as desired in the crank chamber 2, and this pressure control valve 31 is provided in the crank chamber 2 as desired.
8 and a suction chamber 32 that communicates with the suction side;
the pressure-responsive member 34 that moves the valve body 33 and the amount of current I applied to the electromagnetic coil 35. Solenoid 3 moves according to ,
6, and the amount of current to the electromagnetic coil 35 is ■. , to adjust the amount of blow-by gas that leaks from between the piston 29 and the cylinder bore 30 into the crank chamber within two days and returns to the suction side.

Thus, a capacity variable device 37 that changes the capacity of the compressor 18 is configured from the pressure control valve 31 and the like, and the electromagnetic coil 3
When the current 11sot flowing through the crank chamber 28 increases and the magnetic force of the solenoid 36 increases, a force acts on the valve body 33 in the direction of restricting communication between the crank chamber 28 and the suction chamber 32, causing blow-by leaking from the crank chamber 28 to the suction chamber 32. The amount of gas decreases. As a result, the pressure inside the crank chamber 28 increases and the force acting on the back surface of the piston 29 increases, so the wobble plate 26 rotates about the hinge ball 27 in a direction that reduces the swing angle. The stroke of the piston 29, ie, the capacity of the compressor, becomes smaller.

The capacity variable device 37 is not limited to the one that adjusts the amount of blow-by gas returned to the suction side using a pressure control valve as described above, but also the one that changes the number of cylinders used by the compressor, or the one that changes the number of cylinders used in the compressor, or the one that changes the number of effective vanes in a vane type compressor. Any device that can substantially change the capacity, such as a device that changes the number of sheets may be used.

The actuators 6, 11, 16° 17, the motor 7a of the blower 7, the electromagnetic clutch 23 of the compressor 18, and the variable capacity device 37 are each driven by a drive circuit 40a.
It is controlled based on the output signal from the microcomputer 41 via .about.40f. This microcomputer 41 includes a central processing unit (CPU) (not shown), a read-only memory (formerly referred to as "Random Access Memory (RAM)"),
This microcomputer 41 is a well-known device having an input/output board (Ilo), etc., and the microcomputer 41 receives an output signal from a vehicle interior temperature sensor 42 that detects the temperature inside the vehicle, and an output signal from an outside temperature sensor 43 that detects the outside temperature. An output signal from a solar radiation sensor 44 that detects the amount of solar radiation, which is provided on the downstream side of the evaporator 8, and determines the temperature of the evaporator 8 or the temperature of the air that has passed through the evaporator 8 as the cooling temperature of the evaporator 8 Tl)IT An output signal from the mode sensor 45 to be detected is selected via a multiplexer (MPX) 46, converted to a digital signal via a /D converter 47, and inputted.

The microcomputer 41 also includes an operation panel 48.
The output signal from is input. This operation panel on the 4th
An AUTO switch 49 cancels the stop mode or manual operation state and sets all air conditioning equipment such as blowers to the automatic state, and an OFF switch 50 commands the stop mode.
, an A/C switch 51 that operates the compressor 18;
an intake switch 52 that switches the intake mode between an internal air intake mode (REC) and an outside air intake mode (PRESH);
It is provided with a DEF switch 53 for setting the blowing mode to a defrost mode, a blowing capacity setting device 55 for setting the blowing capacity, and a blowing mode setting device 56 for setting a blowing mode other than the defrost mode.

The temperature setting device 54 is an up/down switch 54a.

54b and set temperature T. Temperature display section 5 that digitally displays
4c, up/down switches 54a, 54b
With this operation, the set temperature shown on the temperature display section 54c can be changed within a predetermined range.

The blower capacity setting device 55 is composed of a FAN switch 55a that changes the rotation level of the blower 7 and a level display section h5b that displays the current rotation level, and the blower capacity mode is stopped (level 0)
, LO enemy (level 1), old D (level 2), ■ (level 3), and MAX III (level 4).
The characters [IAL] will light up.

Furthermore, the mode setting device 56 sequentially switches the blowout mode in the order of vent, bilevel, and heat, and
6a, and a pictorial display section 56 that graphically indicates the current balloon mode.
When the MODE switch 56a is operated, the air flow arrows 57a and 57b on the picture display section 56b are lit to indicate the selected blowout mode, and 'MAN[IAL] is displayed at the top of the picture display section 56b. The characters ``'' are illuminated.The display of these lighting displays 57a, 57b and the display portions 54c, 55b, 56b is controlled by the microcomputer 41 via the display circuit 58.

In FIG. 4, an example of the control operation of the compressor 18 by the aforementioned microcomputer 41 is shown as a flowchart, and the microcomputer 41 determines whether or not cool-down control is being performed in step 60.
Further, in step 62, it is determined whether or not low temperature demist control is being performed.

Specifically, the cool-down control is a set temperature T.

From the vehicle interior temperature TR%, the outside temperature TA, and the solar radiation ff1qs, for example, the target blowout temperature X,4 is determined by the following formula, and XM=A,
TD+B-Tl+C, TA+D, QS+E (However, A,
(B, C, D, E represent calculation constants) This is started when this X14 becomes less than a predetermined value and the maximum cooling capacity is required.

On the other hand, low-temperature demist control is demist control that is started, for example, when the outside air temperature TA belongs to a predetermined low-temperature range (for example, -6°C to 6°C). Although these calculations and determination processes are not shown, they are performed in advance in a main routine (not shown) before executing this routine.

If it is determined in step 60 that cool-down control is in progress, the process proceeds to step 64 to determine whether the conditions for cool-down control described above are no longer satisfied and the cabin environment has reached a point where it is safe to terminate cool-down control. If cooldown control is still necessary (
If No), the process proceeds to step 66, and the target cooling temperature T'lNT of the evaporator 8 is set to a predetermined temperature α, such as -10''C, which is considerably lower than the freezing start temperature (near 0'C) of the evaporator 8. In this case, the capacity of the compressor 18 is calculated by proportional integration so that the difference between the actual cooling temperature TIN? of the evaporator 8 and the target cooling temperature T', 4T, which will be described later, becomes the relationship shown in (2) 2. The cooling temperature TINF of the evaporator is controlled to approach the target cooling temperature T',M.

l T+14t T'+Nt l <FC...
Equation (2) Therefore, during cool-down control, the capacity of the compressor 18 is maximized, and even if the cooling temperature TINT of the evaporator 8 falls below the freezing start temperature, the compressor 18 is not stopped, and the interior of the vehicle is rapidly cooled. Ru.

If it is determined in step 62 that the low temperature ratio demist control is in progress (YES), the process proceeds to step 70, where it is determined whether the environment has reached a point where it is safe to end the low temperature demist control, and the low temperature ratio demist control is performed. If it is still necessary (NO), for example, as shown in FIG. Proceeding to step 68, the capacity of the compressor is controlled based on this T'lNT.

Therefore, during low-temperature demist control, the cooling temperature T11 of the evaporator 8 is intermittently lower than the freezing start temperature, so that sufficient dehumidifying ability is maintained even when the outside air temperature is low.

On the other hand, if it is determined in step 64 or 70 that the environment is such that cool-down control or low-temperature demist control is to be terminated, step 74 or 76
Go to ``1'' and set the flag requesting termination of these controls.
and step 7 in the same way as normal compressor control.
8, and in this step 78, the target cooling temperature T'
Set lNT to a set value T (for example, 3°C) during normal control.

Thereafter, in step 80, it is determined whether or not the flag is 1'', and if it is not 1, the process proceeds to step 82, where the cooling temperature TINT of the evaporator 8 and the cooling temperature TINT of the evaporator 8 are set in advance to prevent the evaporator 8 from freezing. The predetermined value Tz,
Tt (e.g. Tz=t, 5'c.

T2 = 3°C) to compare and determine the size. In this step 82, if 'reNt is larger than the predetermined value (A), the capacity control of the compressor is continued in step 68 described above, but if it is smaller than the predetermined value (
For B), the process proceeds to step 84 to immediately stop the compressor 18 to prevent the evaporator 8 from freezing.

On the other hand, if it is determined in step 80 that the flag is "1", the process does not immediately proceed to step 82;
Proceeding to step 86, the cooling temperature TI of the evaporator 8 (
For example, it is determined whether the temperature exceeds 1.5°C), and
If INT is smaller than T, the compressor 18 will immediately stop at step 82 even if normal control is restored.
Bypassing step 82 and proceeding to step 68, the TI
If Na≧T1, compressor 1
8 will not stop immediately, the program proceeds to step 88 and sets the flag to "0", and then proceeds to step 82 to restore the antifreeze function of the evaporator.

Note that after step 68, the routine moves to another air conditioning control routine, and then returns to step 60.

Therefore, in the process of transitioning from cool-down control or low-temperature demist control to normal control, the compressor 18 does not stop and continues to operate at a small capacity even if the cooling temperature T''+sa of the evaporator 8 is below T2. This prevents the air conditioning inside the vehicle from changing significantly during the transition to normal control.Furthermore, if the compressor 18 is to stop at the same time as the transition to normal control, cool-down control and low-temperature demist control are performed. Although it is meaningless, the effects of these controls can be fully brought out by guaranteeing the operation of the compressor as described above.

(Effects of the Invention) As described above, according to the present invention, when the disabled antifreeze mechanism is restored, the cooling temperature of the evaporator is north of the predetermined temperature that can prevent freezing.
Even when the anti-freezing function is restored, the compressor does not stop at the same time, and unnecessary stoppage of the compressor during air conditioning control can be prevented and stable air conditioning control can be realized.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram showing this invention, Fig. 2 is a configuration diagram showing an embodiment of the invention, Fig. 3 is a sectional view showing a compressor used in the above, and Fig. 4 is control of the compressor by a microcomputer. 81 is a flowchart showing an example of the process, and FIG. 5 is a characteristic diagram showing changes in the target cooling temperature T''INT of the evaporator and the actual cooling temperature TINT of the evaporator in low-temperature demist control. 8... Evaporator, 18... Combrelada, 45
...Mode sensor 100...Anti-freeze control means,
200... Judgment means, 300... Control means. Figure 1 1st day Figure 5 Kanomon -

Claims (1)

[Claims] A cooling cycle including an evaporator through which inhaled air passes and a compressor that supplies refrigerant to the evaporator; a mode sensor that detects the cooling temperature of the evaporator; and a mode sensor that detects the cooling temperature of the evaporator to prevent freezing. antifreeze control means that stops the compressor when the temperature drops below a predetermined value, and a predetermined environment that requires the compressor to operate even if the cooling temperature of the evaporator falls below the predetermined value. a determining means for determining whether the cooling temperature of the evaporator belongs to the predetermined environment;
The function of the freezing prevention control means is disabled, and if the determining means determines that the cooling temperature of the evaporator does not belong to the predetermined environment, the time when the cooling temperature of the evaporator exceeds a predetermined temperature that can prevent freezing. An air conditioning control device for an automobile, comprising: a restriction means for restoring the function of the antifreeze control means from the point in time.