JP2767880B2 - Vehicle air conditioner - Google Patents

Description

The present invention relates to a vehicle air conditioner having a variable displacement compressor.

B. Prior Art The present applicant previously described in Japanese Patent Application No. 63-196738,
A vehicle air conditioner has been proposed in which dehumidification is sufficiently performed even when the outside air temperature is relatively low (for example, −5 ° C. to 10 ° C.). In the air conditioner, the capacity of the compressor is controlled as follows.

(A) a refrigerant temperature sensor for detecting a refrigerant temperature is provided on an outer surface of a pipe between the evaporator and the expansion valve; (b) upper and lower target refrigerant temperatures are set above and below the external air temperature as reference; C) The upper and lower target refrigerant temperatures are alternately selected at predetermined time intervals. (D) The capacity of the compressor is increased or decreased according to the deviation between the refrigerant temperature measured by the refrigerant temperature sensor and the selected target refrigerant temperature.

Such low-temperature dehumidification control (hereinafter referred to as low-temperature demist control) ensures desired dehumidification performance without freezing the evaporator even under conditions where the outside air temperature is relatively low.

C. Problems to be Solved by the Invention However, when the low-temperature mist control is executed in the inside air circulation mode, the compressor and the electronic circuit that controls the discharge capacity thereof break down, or the compressor breaks due to a break in the harness. If the discharge capacity is fixed at the minimum value, sufficient dehumidification cannot be performed, and the window may be fogged.

A technical object of the present invention is to prevent fogging of a window as much as possible even when a compressor malfunctions.

D. Means for Solving the Problems To be described with reference to FIG. 1 which is a diagram corresponding to claims, the present invention has at least a variable capacity compressor 101, a condenser 102, an expansion valve 103, and an evaporator 104, and introduces outside air and circulates inside air. Is applied to a vehicle air conditioner that can be switched.

As shown in FIG. 1, the present invention comprises a temperature detecting means 105 for detecting an air temperature downstream of an evaporator 104, and a variable displacement compressor 101 so that the detected temperature becomes a target temperature.
Discharge capacity control means 106 for calculating and controlling the discharge capacity of
During the compressor control by the discharge capacity control means 106, the compressor control failure state determination that determines that the compressor control is defective when the discharge capacity of the compressor 101 is minimum and the minimum discharge state continues for a predetermined time period The technical problem described above is solved by providing the means 107 and the switching means 108 for switching to the introduction of outside air when the control failure state is determined.

E. Function The air temperature downstream of the evaporator 104 is detected, and the variable capacity compressor is set so that this air temperature becomes the target air temperature.
The discharge capacity of 101 is controlled. When the compressor 101 has been operating for a predetermined time or more with the minimum capacity, the compressor control failure state determining means 107 determines that the compressor control is in a failure state, and switches to the outside air introduction to the switching means. Thereby, the outside air is introduced, and the fogging of the window is suppressed.

F. Embodiment An embodiment of the present invention will be described with reference to FIGS.

(I) Configuration of Embodiment <I-1: Overall Configuration> As shown in FIG. 2, a vehicle air conditioner according to the present invention comprises a variable displacement compressor 2, a condenser 3, and an evaporator 4 driven by an engine 1. Unit 100 for the compression refrigeration cycle, comprising a liquid tank 5 and an expansion valve 6
It has. The variable displacement compressor 2 has a suction pressure
When Ps exceeds the set pressure Pr, the inclination angle is increased to increase the discharge capacity, and the set pressure Pr is controlled by a solenoid current _ISOL supplied from the control circuit 40 shown in FIG. Further, the evaporator 4 is disposed in an air conditioning duct 7 having an outside air inlet 7a and an inside air inlet 7b.

Inside and outside air switching doors 8 for controlling the flow rate of air introduced into the air conditioning duct 7 are provided at each of the inlets 7a and 7b. Further, in the air conditioning duct 7, a blower fan 9, a heater unit 10, and an air mixing door 11 are provided as is well known, and the amount of air blown out from a vent outlet 7c and a foot outlet 7d provided in the air conditioning duct 7 is respectively set. A vent door 12 and a foot door 13 to be adjusted are provided. Further, a defroster door 14 is provided at a defroster outlet 7e provided in the air conditioning duct 7.

<I-2: Variable Displacement Compressor> The variable displacement compressor 2 will be described with reference to FIG. This is a so-called swash plate type, in which the suction pressure Ps or the discharge pressure Pd is guided into a casing in which the swash plate is disposed, and thereby the discharge angle is changed by changing the inclination angle of the swash plate. It is disclosed in Japanese Unexamined Patent Publication No. 58-158382.

That is, in FIG.
A rotary shaft 24 that rotates via a pulley 23 by a belt 22 driven by the engine 1 is provided in the rotary shaft 21. A rotary drive plate 25 that rotates integrally with the rotary shaft 24 is pivotally supported on the rotary shaft 24. It is inclined. The journal 25a of the rotary drive plate 25 is provided with a non-rotary whip 26, and a piston 28 sliding in a cylinder block 27 is connected to the non-rotary wap 26 via a rod 29. Therefore,
When the rotary drive plate 25 rotates, the piston 28
Reciprocates, and sends out the refrigerant sucked from the suction side chamber 30s to the discharge side chamber 30d and sends it to the condenser 3 by pressure. As is well known, a plurality of pistons 28 are arranged at equal intervals on a circumference around the axis of the rotating shaft 24.

Here, the inclination angle of the non-rotary whipple 26 is equal to the suction pressure Ps in the casing 21, that is, in the casing chamber 21R.
Alternatively, the suction pressure Ps is changed by adjusting the pressure difference before and after each piston 28, in other words, by adjusting the pressure difference between the cylinder chamber and the casing chamber, by inducing the discharge pressure Pd, and as shown in FIG. 3 (b). When the discharge pressure Pd is derived as shown in FIG. 3 (c), the inclination angle is reduced. For such tilt angle control, the compressor 2 is configured such that the casing chamber 21R is connected to the suction side chamber 30s or the discharge side chamber.
For the purpose of selectively communicating with 30d, inside the end cover 31,
The control valve 32 is shown in detail in FIG.

<I-3: Control Valve 32> FIG. 4 shows a detailed internal structure of the control valve 32. The control valve 32 has a valve body 322 in which a valve seat member 321 is fitted at the distal end side opening. A valve pin 324 having a ball 323 integrally attached to the distal end is inserted into the valve body 322. Inside the valve body 322, a high-pressure chamber 328 communicating with the discharge side chamber 30d at the port 327, and a port 3
A chamber 330 communicating with the casing chamber 21R is formed through 29A and 329B, and the ball 323 is pressed against the seat 326 by the spring 325 to shut off both.

An end cap 332 having a bellows 331 therein is mounted on the base side of the valve body 322. A spring seat 333 and an end member 334 are attached to both ends of the bellows 331, and a bellows 33 is provided by a spring 335 interposed between the spring seat 333 and the end member 334.
1 is urged in the extension direction.

Further, the end member 3 is inserted through the concave portion of the spring seat 333.
A rod 336 is provided to penetrate through the valve 34, and the tip of the rod 336 comes into contact with a concave portion provided at the base of the valve pin 324.

Between the end cap 332 and the bellows 331, a control chamber communicating with the suction side chamber 30s via ports 337 and 338 formed in the end cap 332 and the end cover 31, respectively.
The control chamber 339 is configured to communicate with the chamber 341 via a passage between a valve body 340 provided at the base of the valve pin 324 and a seat 343 of the valve body 322. This room 341
Is connected to the casing chamber 21R via the port 342.

Further, a movable plate 343 is fixed to the spring seat 333, and the plunger 345 of the electromagnetic actuator 344 is connected to the movable plate 343. A return spring 346 for pressing the movable plate 343 against the spring seat 333 is provided around the electromagnetic actuator 344. The spring force of the return spring 346 is made sufficiently larger than that of the spring 335. The solenoid section of the electromagnetic actuator 344 is connected to an output circuit 49 via a relay 56 as shown in FIG. 5, and is controlled by a solenoid current _{ISOL as} described later.

Generally, when the suction pressure Ps of the compressor 2 exceeds a preset pressure Pr (hereinafter, set pressure), the control valve 32 operates. That is, the bellows 331 contracts against the spring force of the spring 335, the rod 336 is displaced downward, and the spring force of the spring 325 causes the valve pin 324 to follow its descending operation (at this time, the movable plate 343 is immovable. is there). Thus, the ball 323 is seated on the seat 326, and the valve body 340 is separated from the seat 343. FIG. 3 (b) schematically shows this state. As can be seen from this figure, the suction pressure Ps is supplied from the control chamber 339 to the chamber 341 and the port 3
It is guided to the casing chamber 21R via 42, the inclination angle increases, and the discharge capacity increases.

If the suction pressure Ps is lower than the set pressure Pr, the spring
The rod 336 pushes the valve pin 324 upward by the spring force of 335, the valve body 340 is seated on the seat 343, and the ball
The 323 moves away from the sheet 326 (at this time, the movable plate 343 is not moved). FIG. 3 (C) schematically shows this state.
It is. As can be seen from this figure, the high pressure chamber 328 and the chamber 330
And the discharge pressure Pd through the port 329B and the casing chamber 21R
And the inclination angle is reduced, and the discharge capacity is reduced.

Here, the upper set pressure Pr is changed and controlled as follows.

When the solenoid portion of the electromagnetic actuator 344 is demagnetized, the movable plate 343 is in a position where the springs 335 and 326 are balanced, and the movable plate 343 moves upward in proportion to the increase of the solenoid current, and The spring force of 335 increases in proportion to the solenoid current. As a result,
The set pressure Pr of the control valve 32 also increases in proportion to the solenoid current.

<I-4: Control Circuit 40> FIG. 5A shows an example of the control circuit 40 of the vehicle air conditioner according to the present invention. An external temperature sensor 43 for detecting an outside air temperature T _AMB and a vehicle interior temperature T _INC
Room temperature sensor 44 for detecting a solar radiation sensor 45 for detecting the amount of solar radiation Q _SUN, evaporator 4 downstream of the air temperature (hereinafter, the suction temperature of) suction temperature sensor 46 for detecting the T _INT, the outlet side pipe surface of the expansion valve 6 A coolant temperature sensor 47 for detecting the coolant temperature Tref and a coolant temperature sensor 48 for detecting the engine coolant temperature Tw are connected to the CPU 41, and various kinds of temperature information and heat amount information are inputted to the CPU 41 from these sensors 43 to 48. In addition, the input circuit 42 includes an air conditioner switch 57, a blower fan switch 58, an ignition switch 59, a defroster switch 60, an intake pressure sensor 61 for detecting an intake pressure of an intake manifold, a rotational speed sensor 62 for detecting a rotational speed of the engine, An air mix door opening sensor 63 for detecting the opening of the air mix door 11 and an inside / outside air switching door sensor 64 for detecting the position of the inside / outside air switching door 8 are also connected.

Further, the CPU 41 receives an intake actuator 50, an aerial door actuator 51, a vent door actuator 52, and a foot door actuator 5 via an output circuit 49.
3. The defroster door actuator 54 and the blower fan control circuit 55 are connected, and the blower fan motor 9 is connected to the blower fan control circuit 55. The solenoid circuit of the electromagnetic actuator 344 attached to the control valve 32 is further connected to the output circuit 49 via the relay 56. The intake door actuator 50 switches the inside / outside air switching door 8 between an outside air introduction position and an inside air introduction position.

The CPU 41 has sensors 43 to 48, 61 to 64, and switches 57 to 60.
Based on various information input from the controller, various actuators such as the intake actuator 50 and the air-mix door actuator 51 are driven and controlled to appropriately set the air inlet, outlet and outlet temperature or the set output Pr of the control valve 32. Control. Further, the blower fan motor 9 is drive-controlled by the blower fan control circuit 55 by the air flow control signal to appropriately control the blower fan air flow. (II) Operation of the Embodiment Next, the operation of the embodiment will be described.

<II-1: Basic Flowchart> FIG. 6 is a flowchart showing the basic control of the air conditioning control device executed by the CPU 41.

In step S10, initial settings are made. In the normal auto air conditioner mode, for example, the set temperature _TPTC is initially set to 25 ° C. In step S20, various information from each sensor is input.

The data information of each of these sensors will be specifically described. The set temperature T _PTC is obtained from a control panel (not shown), the vehicle interior temperature T _INC is obtained from the indoor temperature sensor 44, and the outside air temperature is obtained.
T _AMB is provided from the outside air temperature sensor 43, the suction temperature T _INT is provided from the suction temperature sensor 46, and the refrigerant temperature Tref is provided from the refrigerant temperature sensor 47. Further, the engine water temperature Tw is determined by the water temperature sensor 48.
Therefore, the solar radiation amount Q _SUN is given from the solar radiation sensor 45.

Next, in step S30, the outside air temperature _TAMB obtained from the outside air temperature sensor 43 is processed to a value _TAM corresponding to the actual outside air temperature, excluding the influence from other heat sources. Then step S
At 40, the solar radiation amount information as the amount of light from the solar radiation sensor 45 is processed into a value Q ' _SUN as a heat amount suitable for subsequent conversion.
In step S50, the set temperature T _PTC set on the control panel is processed to a value T ′ _PTC corrected according to the outside air temperature. In step S60, a target outlet temperature To is calculated from T ′ _PTC , T _INC , T _AN , and Q ′ _SUN, and the air mix door 11 is calculated according to the deviation between the target outlet temperature To and the actual outlet temperature.
Is calculated. In step S70, the compressor 2 is controlled as described below. In step S80, each outlet is controlled. In step S90, selection switching of the air inlets, that is, the outside air inlet 7a and the inside air inlet 7b, is controlled.

In step S100, the air flow from the outlet is controlled by controlling the blower fan 9.

<II-2: Compressor control> FIG. 7A shows the compressor control (step
It is a flowchart explaining (S70) in detail.

In FIG. 7A, in step S701, it is determined whether or not the blower fan 9 is operating (is turned on) based on a signal from the blower fan switch 58. If not, the compressor 2 is stopped in step S702 ( Off). If it is operating, in step S703, the detected refrigerant temperature
Based on Tref, state 1 or state 2 is read and the state is stored in a predetermined storage area. Note that Tr in step S703
ef ₁ is the refrigerant temperature when the heat load is small, and Tref ₂ is
The refrigerant temperature is somewhat higher than Tref ₁ . Note that this T
ref ₁ is the outside air temperature T _AM in the low-temperature mist control described later.
A lower coolant temperature than the reference refrigerant temperature T ₂₁ defined from. Next, when it is determined that the state is 2 in step S704,
In step S702, the compressor is stopped.

According to steps S703, 704, and 702 described above, breakdown of the compressor is reliably prevented. That is, under the condition that the flow rate of the refrigerant is extremely small (for example, low-temperature demist control in a predetermined low outside air temperature range described later), the heat load of the wind passing through the evaporator on the evaporator is extremely small, and the state of the refrigerant inside the evaporator is not good. Since the compressor becomes stable and adversely affects the compressor, the compressor is turned off when the refrigerant temperature falls below a predetermined value.

When it is determined that the state is 1, in step S705, the state of the engine speed is determined based on the signal from the speed sensor 62. When the engine speed is in the low rotation range (as shown in FIG. between) until the rise to a predetermined rotational speed Rref ₂ proceeds to step S706, the when the high speed region until the rotational speed as shown in (Fig. (b) is reduced to a predetermined rotational speed Rref ₁₎ Goes to the destroke control of step S712. The high and low rotation regions are determined as shown in FIG. 7B according to the number of rotations. In step S706,
Based on the corrected outside air temperature T _AM , any one of the states 3 to 5 is determined and stored in a predetermined storage area.
Proceed to S707. In step S706, _TAM1 and
T _AM2 is a state in which the outside air temperature is extremely low, and T _AM3 and T
_AM4 refers to a state where the outside air temperature is high to some extent.

In step S707, it is determined whether or not the defroster switch 60 is on, and if it is off, in step S708,
It is determined whether or not the target outlet temperature To calculated in step S60 is equal to or lower than a temperature Trcd at which the air mixing door 11 blocks all the air flowing into the heater unit 10. If Trcd or less, the process proceeds to step S709 to perform rapid cool-down control.

The determination in step S708 is made only once when the ignition switch 59 is turned off and on, or only once when the blower fan switch 58 is turned off and on.

<II-3: Rapid Cool Down Control> FIG. 8A shows a flowchart of the rapid cool down control in step S709 of FIG. 7A. In step S7091, the target temperature of the outlet side of the air passing through the evaporator (hereinafter goal suction temperature) t ₁ to T _'INT with a temperature T ₁ of the freezing start possible temperature below the evaporator, as measured time Time1 timer Set.

Here, the reason the temperatures T ₁ according to the target suction temperature T _'INT, if the ambient temperature as in summer day is high, further than the actual air temperature T _INT freezing start possible temperature of the evaporator downstream even if lower temperatures T ₁ is due to the present inventor has confirmed that not freeze if within a predetermined time,
Moreover, by this way decrease the target suction temperature T _'INT as the temperature T _1, can lower the set pressure Pr of the control valve 32 for adjusting the discharge capacity of the compressor 2,
Therefore, the discharge capacity of the compressor 2 can be kept large in the region of the lower suction pressure Ps, and the cooling capacity can be sufficiently exhibited.

Next, in step S7092, the solenoid energizing current I
Calculate _SOL1 .

As shown in the flowchart of FIG. 9, this calculation is performed by first calculating the difference (T T between the suction temperature T _INT and the target suction temperature T ′ _INT
INT -T _'INT) is calculated (steps S 941), determined in step S942 in accordance with FIGS. 10 and 11 respectively proportional term current I _P and the integral-term electric-current I _I from this difference. Here, the proportional term current I _P first based on the difference calculated in step S 941 11
From the figure, the integral term current I _I is calculated from FIG. 10 based on the same difference, and ΔI _I is obtained as a value I _I (= I _I + ΔI _I ) obtained by adding ΔI _I to the previous I _I. Desired. In step S943, it obtains the current corresponding to the difference between the proportional term current I _P and the integral-term electric-current I _I as a solenoid energization current I _SOL1. That is, the solenoid energizing current I _SOL1 is obtained by the following equation: I _SOL = I _P −I _I (1)

However, I _P amps, _I I is milliamps.

In Step S7093 of FIG. 8 (a), the suction temperature T _INT is determined whether freezing start possible temperature T _4, executes an iteration step S7092 and step S7093 until the affirmative, T _INT = T _{When the} count reaches ₄ , in step S7094, counting of the timer Time1 is started, and the flow advances to step S7095. In step S7095, similar to step S7092 to calculate the solenoid energization current I _SOL1. Then, in step S7096, it determines the target air temperature To is whether the temperature T ₅ or more. Here, the temperature T ₅ is determined when the air mix door 11 is
The temperature is such that the flow of air into 10 starts. Step S7096 is affirmative the process proceeds to step S7098, and determines whether or not the timer Time1 has completed the counting of t ₁ in If a negative step S7097. If step S7097 is denied, the process returns to step S7094. If affirmative, step S70
Proceed to 98 and set the evaporator target suction temperature _T'INT to 1 degree /
Increases every second.

Accordingly, FIG. 10, as it can be seen from FIG. 11 and Expression 1, at the time of rapid cool-down, I _SOL1 is suction temperature T _INT of the evaporator 4 decreases rapidly to a temperature T _1. When the solenoid current I _SOL1 decreases, the movable plate 343 of the electromagnetic actuator 344 shown in FIG. 4 is displaced downward, and the set pressure Pr for opening the valve body 340 decreases. As a result, even if the compressor suction pressure Ps is a small value, the valve body 340 opens and the suction pressure Ps is guided to the casing chamber 21R, and the inclination angle is increased, that is, the compressor discharge capacity is increased (cooling capacity is increased).

Such control is, as shown in the characteristic diagram of FIG. 8 (b), continuing from the suction temperature T _INT is reduced to a temperature T ₄ t ₁ minute or until the target air temperature To is a temperature T ₅ or more, Is done. That is, it is possible to only compressor 2 inlet temperature T _INT predetermined time remain set to a temperature T ₁ is being executed overstroke operation is rapid cool-down control, is cooled rapidly cabin, such as during the summer day.

On the other hand, in step S708 of FIG.
When To is not lower than the temperature Trcd, in step S710, it is determined whether or not the vehicle is in an acceleration state based on the intake pressure of the intake manifold detected by the intake pressure sensor 61. _INT is
_Judge whether it is less than T _INT1 degree. If affirmative, step S
At 712, destroke control is executed.

<II-4: Destroke Control> FIG. 12 (a) shows a flowchart of the destroke control. In step S7121, it is determined whether or not T _INT > T ′ _INT +1. If not, the process proceeds to step S7122,
If affirmative, the process proceeds to step S7123. In step S7122, the target air temperature T _'INT is increased by ₁₀ ° T, the supply in the next step S7124, the solenoid of the electromagnetic actuator 344 based on the first equation from the graph of FIG. 10 and FIG. 11 described above The current value I _SOL1 is controlled. On the other hand, in step S7123, the target air temperature T _'INT the T ₁₁ degrees (>
As T _10), for controlling the electromagnetic actuator 344 by the current value I _SOL1 obtained from the first equation in the same manner in step S7124.

That determines, in step S7121, the relative comparison between the target inlet temperature T _'INT and the suction temperature T _INT, the cooling state of the current evaporator. A negative result means that the evaporator is operated to approach the target value to some extent, and in step S7122, the target suction temperature T '
Current value by increasing the _INT only T ₁₀ ° is relatively small numerical
Determine I _SOL1 . As a result, the movable plate 343 in FIG. 4 moves upward, the spring force of the spring 335 increases, the set pressure Pr of the control valve 32 is set higher, and the suction pressure Ps of the compressor 2 becomes higher than before. Even in this state, the compressor discharge pressure Pd is guided into the casing chamber 21R, and the inclination angle is kept small. In this case, when the target suction temperature _T'INT increases, the actually detected suction temperature T '
_{Since INT} increases and the deviation from the target outlet temperature To changes, and the air mix door 11 is driven to the closing side, the outlet temperature does not increase even if the refrigerant flow rate decreases.

The opening of the air mix door 11 is controlled as shown in FIG. 12 (b).

In FIG. 12 (b), constants A to G are initialized in step S601, and in step S602, the current air mix door opening X is input based on the signal of the air mix door opening sensor 63. Next, in step S603, a deviation S between the target outlet temperature To and the actual outlet temperature is determined based on the illustrated equation. Then, in step S604, the deviation S is set to a predetermined value So.
Compare with If S <−So, the air mix door opening is set to the cold side, that is, the heater unit 10 in step S605.
To the closed side so that the flow rate of air passing through is reduced.
In the case of S> -So, the opening of the air mixing door is set to the hot side, that is, the opening side so that the air flow rate passing through the heater unit 10 is increased. In the case of | S | ≦ + So, the current opening degree is maintained as it is.

On the other hand, the fact that step S7121 of the destroke control is denied means that the air temperature sucked through the evaporator
T _INT While cooling capacity of is the evaporator ₁₀ degrees or less T is considerably exhibited means that the target inlet temperature T _'INT yet there is gap, the cooling performance is to focus on acceleration performance while ignoring some extent Therefore, to increase the solenoid energization current I _SOL1 by the evaporator target suction temperature T _'INT to T ₁₁ degrees. Here, the predetermined temperature T ₁₁ is determined experimentally at a temperature corresponding to the evaporator downstream air temperature of the discharge capacity without stopping the compressor while minimizing. Therefore, the movable plate 343 moves further upward than in the case of step S7122, and the set pressure of the control valve 32 is
Pr is set higher than in the above case, and even if the suction pressure Ps of the compressor 2 becomes considerably high, the casing chamber 21
The compressor discharge pressure Pd is guided into R, and the inclination angle is kept small.

The above steps S7121 to S7123 are also executed when it is determined in step S705 in FIG. 7A that the engine speed is high.

As described above, the destroke control is executed at the time of acceleration or during operation in the high engine speed range, and each destroke control has the following operational effects.

De-stroke control during acceleration This de-stroke control is executed during acceleration and when the evaporator suction temperature T _INT is equal to or lower than T _INT1 degree.
When the evaporator suction temperature T _INT is equal to or lower than T _INT1 degree, the cooling capacity of the evaporator is considerably exhibited, and the acceleration performance is improved at the expense of some cooling performance. That is, when the destroke condition is determined, the set pressure Pr of the control valve 32 is increased and the compressor 2
Even if the suction pressure Ps of the casing becomes relatively large, the casing chamber 21R
The compressor discharge pressure Pd is derived to reduce the discharge capacity of the compressor. As a result, the absorption horsepower of the compressor is reduced and the acceleration performance is improved.

In this case, if the current cooling is almost sufficient, specifically, if the suction temperature T _INT has almost reached the target suction temperature T ′ _INT , the set pressure Pr of the control valve 32 is set slightly higher, Improve acceleration performance while maintaining cooling performance to some extent. On the other hand, the suction temperature T _INT is _equal to the target suction temperature T ′ _INT
If there is still a gap, the set pressure Pr of the control valve 32 is set higher, and the acceleration performance is more important than the former, ignoring the cooling performance.

De-Stroke Control in High Speed Range When the engine speed is in the high speed range, the variable displacement compressor also rotates at high speed, adversely affecting its durability.
Further, if the rotation speed is high, the required refrigerant flow rate can be obtained even if the inclination of the compressor is small. For this reason, in the high-speed rotation region, the inclination angle of the variable displacement compressor is reduced to reduce the reciprocating speed of the piston, thereby improving durability.

If step S711 in FIG. 7A is denied,
In step S713, it is determined whether the air conditioner switch 57 is on. If on, jump to step S716,
If it is off, it is determined at step S714 which of the above-mentioned states 3 to 5 respectively. If state 3, step S715
In step S702, control goes to step S702 to turn off the compressor 2.

<II-5: Fuel Saving and Power Saving Control> FIG. 13 (a) shows a flowchart of fuel saving and power saving control. In step S7151, it is determined whether the outlet is in the bilevel (B / L) mode. If the mode is the B / L mode, the process proceeds to step S7152; if the mode is not the B / L mode, the process proceeds to step S7153.
Proceed to. In step S7152 and S7153, according to the graph of FIG. 13 (b), obtaining the target suction temperature T _'INT from the target air temperature To. That is, in the B / L mode, the target suction temperature _T'INT is set according to the characteristic diagram II, and in modes other than the B / L mode, the target suction temperature _T'INT is set according to the characteristic diagram I.

Then, the process proceeds to a step S7154, the suction temperature T _INT is read either on whether the temperature range defined by the temperature T ₆ is freezing start possible temperature T ₄ and a temperature slightly lower than, or state 7 in step S7155 If it is affirmative, that is, if the state is 7, the process proceeds to step S715.
At 7, the compressor is turned off and the process returns to the predetermined process. on the other hand,
When it is determined that the state is 6, in step S7156, the solenoid current value I _SOL1 is controlled in the same manner as described above, and the process returns to the predetermined process.

According to the above procedure, the compressor is extremely finely controlled so that the suction temperature _TINT is in accordance with the target blowout temperature To, and fuel saving and power saving are achieved for the following reasons.

As before, the current suction temperature T _INT and the target outlet temperature To
When the desired opening temperature is obtained by adjusting the opening degree of the air mixing door 11 due to the deviation from the above, the suction temperature _TINT may be undesirably too low depending on the operating condition. And the blowing temperature is controlled to the target value. For this reason, the compressor wastefully uses power and adversely affects fuel economy.

According to this embodiment, for a certain target outlet temperature To,
In order to obtain the temperature, the air temperature downstream of the evaporator 4, that is, how much the suction temperature _TINT should be determined is determined as an experimental value, and a target calculated according to the graph of FIG. From the outlet temperature To, the target suction temperature T '
_INT is determined, and the discharge capacity of the compressor is controlled based on the target suction temperature T ′ _INT so that the suction temperature T _INT does not decrease excessively. This means that the compressor is operated with the minimum required displacement (inclination angle), and therefore the absorption horsepower is reduced, contributing to power saving and fuel saving.

By the way, as in this embodiment, operating the compressor with the minimum necessary capacity means that the suction temperature T _INT is extremely close to the target outlet temperature To, and the larger the deviation between the two, the larger the opening degree. Controlled air mix door 11
Is almost completely closed. Therefore, the outlet is B / L
When the mode is set, for example, the temperature of the air blown out from the underfoot outlet 7d is substantially equal to the temperature of the air blown out from the vent outlet 7c, so that the effect of so-called cold head heat cannot be obtained. Therefore, in the B / L mode, the power saving and fuel saving effects in the above sense are slightly reduced.
By setting _TINT to a low value, the air mix door 11 tends to be opened, and for example, the temperature of the air blown out from the underfoot outlet 7d is increased, thereby obtaining the effect of head cold foot heat.

That is, for the same target air temperature the To, B / target inlet temperature T in the L-mode _'INT is the target inlet temperature T in other modes' is set lower than _INT, the B / L mode to other modes In comparison, the solenoid current I _SOL1 according to the first equation is smaller, the suction temperature T _INT for the same target outlet temperature To is smaller, and as described above, the air mix door 11 is set to the open side, and the effect of head-feeling foot heat is obtained. Is obtained.

In FIG. 7A, when step S707 is affirmative, that is, when the defroster switch 60 is on, the states 3 to 5 stored in step S706 are determined in step S716, and according to the result, Various controls are performed.

That is, in the case of state 3, in step S717, MA
X Dehumidification control is performed.

<II-6: MAX Dehumidification Control> FIG. 14 is a flowchart of the MAX dehumidification control. In step S7171, it sets the target suction temperature T _'INT freezing start possible temperature T ₄ ° as described above. Next, step S717
In 2, it reads or state 6 or 7 based on the inlet temperature T _INT, if it is determined that the state 7 in step S7173,
In step S7174, the compressor 2 is turned off. If it is determined that the state is 6, in step S7175, the solenoid current I _SOL1 of the electromagnetic actuator 344 is controlled based on the above-mentioned first formula, FIGS. 10 and 11, as shown in FIG.

On the other hand, if the state 4 is determined in step S716 in FIG. 7A, low-temperature mist control is performed in step S718.

<II-7: Low-temperature mist control> FIGS. 15A and 15B are flowcharts of the low-temperature mist control. In this control, the current supplied to the electromagnetic actuator 344 is controlled by the refrigerant temperature Tre when outside air is introduced.
17 and 18 based on f and the target refrigerant temperature T'ref.
It is calculated based on the first equation based on I _P and ΔI _I obtained from the graph in the figure, and is calculated based on I _P and ΔI _I obtained from FIGS. 10 and 11 described above during internal air circulation. Hereinafter, the low-temperature mist control will be described step by step.

First, in step S7281, it is determined from the signal from the inside / outside air switching door sensor 64 whether the inside air is circulating or the outside air is introduced. If air introduction flow proceeds to step S7282, using the corrected ambient temperature T _AM, calculates a reference refrigerant temperature T _21, T ₂₂ from the graph of FIG. 15 (d). In step S7283, it is determined whether the detected refrigerant temperature Tref is state 21 or state 22. State 21
If so, the flow jumps to step S702 in FIG. 7 to turn off the compressor.

Proceed to state 22 and step S7181 (FIG. 15 (b)), and set the outside air temperature T _AM + T ₈ as the target refrigerant temperature T′ref ₂ ,
The outside air temperature T _AM -T ₉ is set as the target refrigerant temperature T′ref ₃ . In addition, the ₂ minutes t the timer Time2, timer Time3
Set t ₃ minutes respectively. Next, in step S7182, it is determined whether or not the flag 1 is 0.
At 183, it is determined whether or not the flag 2 is 0. If an affirmative decision in step S7184, and starts measuring Time2, in step S7185, first select the target refrigerant temperature T'ref ₃ as T'ref, in step S7186, the Figure 16 the solenoid current I _SOL2 We ask by procedure. This is the first
7 as shown in Figure and the graph of FIG. 18, except for obtaining the proportional term current I _P integral term current I _I in the target refrigerant temperature T'ref is the same as the procedure of the solenoid current I _SOL1 of Figure 9 The description is omitted.

Next, in step S7187, it is determined whether or not the time measurement of Time2 has been completed. Before the timing is completed, the determination is negative and the process proceeds to step S7194, where 1 is set to the flag 1 and the process returns to the predetermined procedure. On the other hand, when the time measurement of Time2 is completed, in step S7188, the flag 1 is set to 0, and in step S71
Start time measurement of Time3 at 89. Then, in step S7190, the flow advances to step S7191 to select the target refrigerant temperature T'ref ₂ as T'ref, controls the solenoid current I _SOL2 in a similar manner as described above. Further, in step S7192, Time
It is determined whether or not the time measurement of 3 is completed. If the time measurement is not completed, the process proceeds to step S7195 to set 1 to the flag 2 and returns to the predetermined procedure. Upon completion of the clocking, the flag 2 is set to 0 in step S7193, and the process returns to the predetermined procedure.

According to the FIG. 15 (b) to indicate the procedure step S7181～S7195, over time, and the target refrigerant temperature T'ref ₃ and T'ref ₂ is selected as Fig. 15 (c) I _SOL2 is adjusted. As a result, T'ref ₃ in I _SOL2 when adjusting the T ₉ than the outside air temperature of the refrigerant temperature (e.g., 4 °) dehumidifying and lower are performed. Incidentally, to pulsating driving the compressor by selecting alternately and T'ref ₃ and T'ref ₂ is to prevent the seizure of the compressor to improve the oil lubrication during operation the flow rate of the refrigerant is small.

On the other hand, if it is determined in step S7281 (FIG. 15 (a)) that internal air circulation is to be performed, the process proceeds to step S7284, and it is determined whether or not immediately after switching to internal air circulation. If affirmative, it is determined in step S7288 whether or not the flag 3 is 0. If affirmative, counting of the timer Time4 is started in step S7289.
Then, in a step S7290, it is determined whether or not the measurement of the time 4 has been completed.
Is set, and the process proceeds to step S7286. When the measurement of Time 4 is completed, 0 is set to the flag 3 in step S7292, and step S729 is performed.
Continue to 7285. If it is determined in step S7284 that it is not immediately after switching from outside air introduction to inside air circulation, step S7
Continue to 285.

In step S7285, the detected intake air temperature T _INT is determined whether the state 23 or 24, FIG. 7 is in the state 23 (a)
Jump to step S702 to stop the compressor,
In the state 24, the target suction temperature T 'is determined in step S7286.
Set the predetermined temperature T _REC to _INT . This predetermined temperature T _REC is
Greater than 0 degrees is freezing start possible temperature T ₄ lower temperature than. After that, in step S7287, the current I _SOL1 to the solenoid is calculated based on the detected suction air temperature T _INT and the target suction temperature T ′ _INT to control the capacity of the compressor.

According to such a procedure, freezing of evaporator compressor stops when the refrigerant temperature Tref is less than the reference refrigerant temperature T ₂₁ in a low temperature de-misting control execution can be prevented. Then, since the reference refrigerant temperature T ₂₁ exercised on the outside air temperature as in the graph of FIG. 15 (d), ambient temperature range (step S706 of FIG. 7 in which the execution of the low temperature de-misting control is permitted
The relatively low temperature state in the state 4) in the compressor from the reference refrigerant temperature T ₂₁ is set lower does not stop undesirably, sufficient dehumidification is performed. On the other hand, the relatively high temperature condition, because the reference refrigerant temperature T ₂₁ is set higher, the compressor before cooling capacity is excessive can be prevented from freezing of the evaporator is stopped.

Further, when the compressor control is performed based on the refrigerant temperatures Tref and Tref 'during the circulation of the internal air, the refrigerant temperature sensor 47 detects the refrigerant temperature higher due to the warm air in the vehicle interior, and as a result, the cooling capacity becomes excessive and the evaporator may freeze. There is.
Therefore, at the time of internal air circulation, the compressor is controlled by the intake air temperatures T _INT and T ′ _INT to suppress the influence of the warm air in the passenger compartment on the dehumidifying performance and prevent the evaporator from freezing.

Furthermore, as can be seen from the graph of FIG. 15 (e) showing the window clearness with respect to the outside air temperature, when the compressor is not driven during the circulation of the inside air (characteristic c), the compressor is driven when the outside air is introduced. Window clearness under the same outside air temperature is worse than that (characteristic a). Especially,
In a low temperature state of 0 degrees or less, the window clearness of the characteristic c is very low. On the other hand, at the time of recirculated air inlet temperature T _INT If becomes equal to or less than the reference suction temperature T ₂₃ of antifreeze is to stop the compressor (Fig. 15 (a) step S7285). However, if the compressor is stopped immediately after switching to the internal air circulation, the window may be rapidly fogged, especially at a low temperature of 0 degrees or less. Therefore, after switching straight to recirculated air as in this embodiment, only the suction temperature T _INT predetermined time even reference intake temperature below has prevent fogging sudden window to drive the compressor.

Also, proceeding to step S7293 following step S7287,
It is determined whether or not the flag 4 is 0. If yes, step
Proceeds to S7294, starts counting time of timer Time5, and proceeds to step S7
At 295, 1 is set to the flag 4. Then, step S7296
, The solenoid current I calculated in step S7287
_It is determined whether or not SOL1 is I ₀ mA.
Go to 7. Here, when I _SOL1 is I ₀ mA, the compressor has the minimum discharge capacity. In step S7297, the timer Tim
It is determined whether or not e5 has completed the timekeeping. If it is determined that the timekeeping has been completed, at step S7298, the intake door actuator 50 switches the inside / outside switching door 8 to the outside air introduction position.
Drive. Then, in step S7299, the flag is set to 0.
And return. Also returns when steps S7296 and 7297 are denied.

According to the procedure of steps S7293 to S7299, when the solenoid current I _SOL1 is equal to or longer than the predetermined time I ₀ mA, it is determined that the control circuit 40 has failed, and the inside / outside air switching door 8 is switched to the outside air introduction position. That is, the low-temperature demist control shown in FIGS. 15 (a) and (b) is performed at the will of the operator for the purpose of improving the dehumidifying performance at a relatively low temperature. It is usually impossible to continue the operation with the minimum capacity, so this is determined as a failure. When the compressor has the minimum capacity, the cooling capacity is the lowest, and the window may be fogged if the internal air is kept circulating. Therefore, when the failure is determined, the window is switched to the introduction of the outside air to suppress the fogging of the window.

In the above-air-conditioning apparatus, since the type of the compressor in I _SOL1 = I ₀ mA is minimized volume has been possible to determine a failure by continuing I _SOL1 = I ₀ mA predetermined time or longer, I _SOL1 = In the type in which the compressor has the minimum capacity at 0, the failure is determined based on whether or not I _SOL1 = 0 has continued for a predetermined time or more. Alternatively, a failure may be determined by detecting the actual inclination angle of the compressor when the compressor is inclined and the minimum inclination angle continues for a predetermined time or more.

In the configuration of the above embodiment, a structure in which the refrigerant temperature sensor 47 guides the refrigerant temperature detecting means 105 to the control valve 32, the suction pressure Ps, and the discharge pressure Pd to the casing chamber 21R,
The CPU 41, in particular, each step of FIGS. 15 (a), (b), and FIG. 16 controls the discharge capacity control means 106, and the CPU 41, particularly, FIG. 15 (a).
Steps S7293 to S7297 constitute the failure detection control means 107, and the intake door actuator 50 constitutes the switching means 108.

In addition, the discharge capacity of the compressor is controlled by the inclination angle of the swash plate, but may be of an oblique axis type. In addition, although the suction pressure or the discharge pressure is guided into the casing chamber to control the inclination angle, other methods may be used.

G. Effects of the Invention According to the present invention, a state in which the compressor is operated for a predetermined time or more with the compressor capacity kept at a minimum is detected to determine a poor control state. However, the fogging of the window can be reliably prevented even if the control falls.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 18 illustrate an embodiment of a vehicle air conditioner according to the present invention. FIG. 2 is an overall configuration diagram, FIG. 3 (a) is an internal structure diagram of a variable displacement compressor, 3 (b) and 3 (c) are diagrams for explaining the operation, FIG. 4 is a detailed internal structure diagram of the control valve, FIG. 5 is a block diagram of a control circuit, FIG. 6 is a basic flowchart, FIG. 7 (a) is a flowchart of compressor control, FIG. 7 (b) is a diagram showing a rotation speed region, FIG. 8 (a) is a flowchart of rapid cool down control, and FIG. 8 (b) is suction at that time. characteristic diagram showing the time variation of the temperature T _INT, flow chart for FIG. 9 controls the solenoid current I _SOL1, graphs for FIGS. 10 and 11 is for calculating a solenoid current I _SOL1, Figure 12 (a ) Is a flowchart of the destroke control, and FIG. FIG. 13 (a) is a flowchart of the fuel saving and power saving control, FIG. 13 (b) is a graph for selecting the two characteristics at that time, and FIG. 14 is the MAX dehumidification control. of the flowchart, the flowchart of FIG. 15 (a) and (b) a low temperature de-misting control, characteristic diagram Fig. 15 (c) shows the time variation of the target refrigerant temperature Tref ₂ and Tref ₃ at low temperature de-misting control, 15 15D is a graph showing the relationship between the outside air temperature and the freezing prevention reference temperature, FIG. 15E is a graph showing the window clearness with respect to the outside air temperature, and FIG. 16 is a solenoid current I.
Flow chart for controlling _SOL2 , FIG. 17 and FIG.
FIG. 18 is a graph for calculating the solenoid current I _SOL2 at the time of low-temperature demist control. 1: Engine, 2: Compressor 4: Evaporator, 8: Inside / outside air switching door 9: Blower fan, 10: Heater unit 32: Control valve, 40: Control circuit 60: Inside / outside air switching door sensor 101: Variable capacity compressor 102: Condenser, 103: expansion valve 104: evaporator 106: temperature detection means 107: discharge capacity control means 108: compressor control failure state judgment means, 109: switching means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Sho 62-146617 (JP, U) Japanese Utility Model Sho 59-136569 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60H 1/00-1/32

Claims (1)

(57) [Claims] 1. A vehicle air conditioner having at least a variable capacity compressor, a condenser, an expansion valve, and an evaporator and capable of switching between outside air introduction and inside air circulation, a temperature detection means for detecting an air temperature downstream of the evaporator, Discharge capacity control means for calculating and controlling the discharge capacity of the variable displacement compressor so that the detected temperature becomes the target temperature; and, during compressor control by the discharge capacity control means, the discharge capacity of the compressor is minimized. And, when the minimum discharge state continues for a predetermined time, the compressor control failure state determination means for determining that the compressor control has failed, and switching means for switching to outside air introduction when determining the control failure state, are provided. Vehicle air conditioner.