JPH0358925B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automotive refrigeration cycle control device used in an automotive air conditioner. In particular, the refrigeration cycle control device of the present invention is used in an air conditioner that uses a compressor whose discharge capacity can be varied.

[Conventional technology]

As shown in Figure 1, a conventional automobile air conditioner has a compression type refrigeration cycle consisting of a compressor 1, a condenser 2, a receiver 3, an expansion valve 4, and an evaporator 5, and each device is connected to a refrigerant pipe. connected sequentially. Since the compressor 1 is driven by an automobile engine (not shown) via an electromagnetic clutch 7, as the engine speed increases depending on the driving condition, the compressor speed also increases. . Then, the discharge amount of the compressor increases or decreases as the rotation speed changes. Therefore, as a result of the cooling capacity changing as the compressor rotational speed increases or decreases, a situation may arise in which the cooling capacity becomes excessive.

Additionally, when the cooling load decreases due to a drop in outside temperature or switching between inside and outside intake air, the cooling capacity becomes excessive as a result, and the fin temperature of the evaporator 5 increases.
In other words, the evaporation temperature of the refrigerant may drop below 0°. In this case, frost will adhere to the fins or they will freeze, reducing the amount of air blown by the blower 8, and as a result, the cooling function will be impaired.

Therefore, in order to prevent this frosting phenomenon and to control the temperature inside the vehicle, the air temperature immediately after the evaporator 5 is detected by a temperature detector 6 such as a thermistor, and the control circuit 9 shown in FIG. Contact 10 of relay 10
By opening and closing a, the electromagnetic clutch 7 was controlled intermittently. That is, by controlling the electromagnetic clutch 7 and adjusting the operating time of the compressor 1, the evaporation temperature of the refrigerant is controlled, and at the same time, the temperature of the air immediately after the evaporator is controlled.

However, with this configuration, if the cooling load decreases or the compressor rotation speed increases, the compression function will become overpowered as described above, and the cooling cycle capacity will exceed the cooling load. Become. Therefore, as shown in Figure 3, the air temperature T immediately after the evaporator 5 decreases, and the set temperature at point C decreases.
T becomes less than ₀ . However, due to its heat capacity, the temperature sensor 6 has a time delay as shown in I in FIG. 3 before the control circuit 9 is activated. That is, during the time I, the air temperature T further decreases and becomes considerably lower than the set temperature T ₀ . Then, when the control circuit 9 operates and the clutch 7 is disengaged at point a,
The compressor is stopped, the expansion valve 7 is closed, and the supply of liquid refrigerant to the evaporator 5 is stopped. Then, the pressure inside the evaporator 5 P _L
increases, and the superheat area of the refrigerant increases, which reduces the effective heat area of the evaporator. As a result, the air temperature T immediately after the evaporator 5 rises rapidly, and becomes equal to or higher than the predetermined temperature T ₀ at point d. However, for the same reason as above, the temperature sensor is closed for the time delay, so the air temperature T continues to rise until point b, at which the control circuit operates. At point d, the control circuit 9 is activated, the clutch 7 is reconnected, the compressor 1 begins to operate, and the above operation is repeated thereafter.

However, since such operations are repeated, the following problems arise.

(1) When the compressor is in operation, the compressor 1 has excess capacity compared to the cooling capacity, but when the compressor is stopped, the cooling capacity decreases due to an increase in the superheat region due to a lack of liquid refrigerant in the evaporator 5, and the overall cooling capacity decreases. This results in wasted effort.

(2) Due to the intermittent operation of the compressor 1, the temperature of the evaporator discharge air fluctuates significantly, which worsens the feeling of cooling.

(3) When the clutch 7 is disengaged, the torque acting on the clutch or friction surface fluctuates greatly, which deteriorates the durability of the clutch.

(4) When the clutch 7 is engaged, a relatively large torque is applied to the engine for driving the vehicle, giving a shock to the occupants and deteriorating the driving feeling.

[Problem to be solved by the invention]

In view of the above points, the present invention uses a variable capacity type compressor that incorporates a variable capacity member that changes the discharge capacity, outputs a control signal to control the variable capacity member, and adjusts the capacity of the compressor itself. The purpose of this control is to significantly reduce the power consumption of the compressor and to prevent a decrease in cooling capacity due to freezing of the evaporator body, etc. Moreover, it is an object of the present invention to eliminate fluctuations in air temperature due to intermittent use of the compressor, thereby improving the feeling of cooling, and further improving the durability of the clutch and the like.

In particular, the present invention corrects the capacity control of the compressor so that when the air temperature on the inlet side of the evaporator is high, the air temperature immediately after the evaporator decreases, so that the evaporator exhibits high cooling capacity in a region where it does not freeze. The purpose is to

In addition, the present invention feeds back the actual capacity of the compressor and makes corrections to make the surface temperature of the evaporator variable based on changes in the capacity of the compressor. The purpose is to enable high cooling capacity to be demonstrated.

〔composition〕

In order to achieve the above object, the present invention includes a first sensing means for sensing the air temperature immediately after the evaporator or the evaporator surface temperature, a second temperature sensing means for sensing the air temperature on the inlet side of the evaporator, The control means is configured to output a drive signal for controlling the variable capacity member of the compressor to the drive device based on a signal from the position detection means for detecting the operating position of the variable capacity member of the compressor. In particular, the control means controls the first temperature signal sensed by the first temperature sensing means, the second sensed temperature signal sensed by the second temperature sensing means, and the operation detected by the position sensing means. The control is performed by correlating the position signals with each other.

That is, the control means receives the first detected temperature signal;
The second detected temperature signal and the operating position signal are input, these signals are combined, and a control signal set for preventing freezing of the evaporator is determined based on this combined value.

[Effect]

By adopting the above configuration, the present invention can maintain an extremely good temperature setting for preventing freezing of the evaporator by correlating the temperature on the suction side and the temperature on the outlet side of the evaporator. . As mentioned above, even if the air temperature immediately after the evaporator is the same, if the air temperature on the inlet side of the evaporator is high, the surface temperature of the evaporator will be higher on average than when the air temperature on the inlet side is low. In the present invention, this characteristic can be skillfully utilized.

That is, when the air temperature on the evaporator inlet side is high and the surface temperature of the evaporator is high on average, the evaporator is less likely to freeze even if the air temperature immediately after the evaporator becomes somewhat low. In view of this, the present invention controls the capacity of the compressor so that when the air temperature on the inlet side of the evaporator is high, the air temperature immediately after the evaporator is lowered, and the refrigerant capacity is high in a region where the evaporator does not freeze. To be able to demonstrate.

Furthermore, in the present invention, even when the capacity of the compressor is varied based on the outlet side temperature and inlet side temperature of the evaporator, the setting for preventing icing of the evaporator is performed using the combined value of the variable capacity signal of the compressor. Since the value is controlled, hunting of the variable capacity member of the compressor can be prevented. At the same time, overshoot and undershoot in evaporator temperature control can also be reduced.

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

Since the refrigeration cycle in the apparatus of the present invention may be the same as that shown in FIG. 1, detailed explanation will be omitted. FIG. 4 schematically shows the entire control system of the device of the present invention. Reference numeral 11 is a resin ventilation casing of an automobile air conditioner. A driving blower 8 is provided. One end of the ventilation casing 11 communicates with an inside air inlet and an outside air inlet through an outside/outside air switching box (not shown), and the other end communicates with an air outlet (an upper cooling air outlet) into the vehicle interior through a heater unit (not shown). , lower air outlet for heating, etc.). A compressor 12 is connected to the refrigerant circuit on the outlet side of the evaporated air 5, and this compressor 12 is connected to an electromagnetic clutch 13.
It is driven by an automobile engine via. Further, the compressor 12 is configured as a variable capacity type having a built-in capacity variable member for varying the discharge capacity, as will be described later.

A temperature sensor 14 is a thermistor for sensing the air temperature immediately after the evaporator 5, and is held in the evaporator 5 so as to be in contact with the heat exchange fins of the evaporator 5. A temperature sensor 23 is a thermistor for sensing the air temperature on the inlet side of the evaporator 5, and is disposed in the middle of the air flow toward the evaporator 5. Reference numeral 24 denotes a position detection device for detecting the position of the variable capacity member built into the compressor 12, and is composed of a potentiometer that is linked to the movement of the variable capacity member. A rotation detector 25 detects the rotation speed of the automobile engine that drives the compressor 12, and a pulse signal of a frequency corresponding to the engine rotation speed, for example, a pulse signal of the ignition coil primary circuit, is applied to its input terminal 25a. It's becoming like that.

15 is a setting resistor that determines the control value of the air temperature immediately after the evaporator. Further, 16 is a control means to which signals of the respective elements 14, 15, 23, 24, and 25 are inputted. That is, the above element 1
4, 23, and 24 are directly connected, and the output of the rotation detector 25 is added to the connection point A between this series circuit and the setting resistor 15, so that the potential at this connection point A is input to the electric circuit of the control means 16. It's getting old.

Reference numeral 17 denotes a servo motor for driving the variable capacity member within the compressor 12, which is controlled by the output of the control circuit 16. 18 is a worm gear for transmitting the driving torque of the servo motor 15 to the variable capacity member of the compressor 12. Reference numeral 19 denotes a relay contact for on/off operation of the compressor 12, which is used to turn off/on energization of the electromagnetic clutch 13. Reference numeral 20 denotes a control circuit that senses the engine speed, outside temperature, etc., and opens the relay contact 19 when these decrease. 21 is an operation switch for the air conditioner, 22
is the in-vehicle power battery.

FIG. 5 shows a specific example of the control means 16, which has two comparators 161 and 162 that receive the potential at the connection point A between the setting resistor 15 and the series circuit, and a first Reference potential V ₁ of comparator 161
is set higher than the reference potential V ₂ of the second comparator 162. The difference between the reference potentials V ₁ and V ₂ can be freely adjusted using the variable resistor 163. The output 161a of the first comparator 161 causes the transistor 16
4a and 164b are turned on and off, and the second comparator 1
Transistor 165 by output 162a of 62
is turned on and off. 166 to 171 are transistors for driving the servo motor 17.

The rotation detector 25 is equipped with a frequency-voltage (F-V) conversion circuit 25b, and its output voltage is configured to decrease as the engine speed increases, as shown in FIG. 6a. . The output voltage of this frequency-voltage conversion circuit 25b is
5c, a transistor 25b, a resistor 25e, and a diode 25f. That is, since the operational amplifier 25c acts so that the output voltage of the circuit 25b and the emitter potential of the transistor 25d become equal,
The collector current of the transistor 25d increases as the engine speed decreases, and decreases as the engine speed increases.

FIG. 6b shows the operating characteristics of the control means 16, which controls the thermistor resistance value _R14 of the temperature sensor 14, the thermistor resistance value _R22 of the temperature sensor 23, and the potentiometer of the position detection device 24. Meter resistance value R Total series resistance of ₂₄ Rs Resistance value of setting resistor 15
The rotation of the servo motor 17 is controlled to be balanced with _R15 , and the output of the rotation detector 25 is used to correct changes in compressor capacity due to fluctuations in engine speed.

Here, for convenience of explanation, the explanation will be made assuming that the amount of correction by the output of the rotation detector 25 is constant.
When the potential V _A exceeds the reference potential V ₁ , the output 161a of the comparator 161 changes from the "Lo" level to the "Hi" level.
conversely, when the potential V _A becomes smaller than the reference potential V ₁ by a constant value V _C , the output 161a returns from the "Hi" level to the "Lo" level. Here, the hysteresis characteristic indicated by the constant value V _C is set by the resistance value of the feedback resistor connected to the first comparator 161.

When the potential V _A of the second comparator 162 exceeds the reference potential V ₂ , its output 162a changes from the "Lo" level to the "Hi" level, and conversely, the potential V _A becomes the reference potential V2.
When the output a becomes smaller than V ₂ by a certain value V _C
returns to the “Lo” level from the “Hi” level.
Here, the hysteresis characteristic indicated by the constant value V _C is set by the resistance value of the feedback resistor connected to the second comparator 162. Also, the reference potential V ₂ is
It is set equal to the potential V _A when R _S and R ₁₅ become equal at a predetermined resistance value (R _S =R ₁₅ =predetermined resistance value).

Next, the configuration and operation of the variable displacement compressor 12 according to the present invention will be described in detail.

In FIGS. 7 to 9, 101 is a shaft, the left end of which is connected to an automobile engine serving as a drive source via an electromagnetic clutch 13 shown in FIG. It is rotated by 102 is fixed to the shaft 101 with a key, and the shaft 1
This is a swash plate that rotates together with the swash plate 10.
The rotation of No. 2 is caused by the piston 104 via the shoe 103.
make a reciprocating motion. Housings 105 and 106 have a cylinder portion 107 that supports the reciprocating motion of the piston 104, and are divided into two parts, front and rear, and die-cast from aluminum or the like.

108 is a suction passage chamber formed within the housings 105 and 106. As shown in FIGS. 8 to 9, the cylinder portion 107 is located at five locations 1
07a, 107b, 107c, 107d, 107
e is formed, and the lowermost cylinder portion 107c
There is a gap of 88° only between and 107d,
The spacing between the other cylinder parts is 68°. Further, the suction passage chamber 108 is located in the ninth
As shown in the figure, it is formed between each cylinder part 107, and all of these suction passage chambers 108 are connected to one refrigerant inlet (not shown), and communicate with the refrigerant circuit on the outlet side of the evaporator 5 through this inlet. There is.

Reference numerals 109 and 110 denote side housings, which are disposed outside the housings 105 and 106 with valve plates 111 and 113 in between. A suction chamber 113 is formed in a portion of the side housings 109 and 110 that directly communicate with each other through a suction side communication hole (not shown), and a portion of the side housings 109 and 110 that faces the piston 104 on the inner periphery of the suction chamber 113 is formed. A discharge chamber 114 is formed at the position. This discharge chamber 114 is connected to the housing 10 through the discharge side communication holes (not shown) of the valve plates 111 and 112.
It communicates with the discharge passage chamber 114a (FIG. 9) of No. 5,106.

115, 116 are valve plates 111, 11
2 and the housings 105, 106; a disk-shaped elastic metal plate made of an elastic metal, for example, spring steel;
Piston 104 of this elastic metal plate 115, 116
A suction valve is formed by providing a U-shaped notch (not shown) at a position facing the intake valve. In addition, housings 105, 106, side housings 109, 11
0 and the valve plates 111, 112 are integrally connected by a through bolt 117, and the through bolt 117 passes through the suction passage chamber 108 in the housings 105, 106 to facilitate assembly. .

118 and 119 are radial bearings using normal needle bearings, and housing 1
An outer race is fixed to 05 and 106 to rotatably hold the shaft 101. 1
Reference numerals 20 and 121 denote slide bearings, which are located between the center portions of the housings 105 and 106 and the swash plate 102, so that the force applied in the thrust direction (axial direction) of the swash plate 102, that is, the swash plate 102
This supports the reaction force received when reciprocating 4.

Reference numeral 122 denotes a shaft seal, which is attached to the side housing 1 located on the drive source side (in other words, on the electromagnetic clutch 13 side) among the side housings 109 and 110.
09 and the shaft 101 to maintain airtightness so that the refrigerant gas and lubricating oil inside the compressor do not leak to the outside.

Reference numeral 123 denotes a holder for the servo motor 17, which is fixed to the rear side housing 110 with screws 124. Worm gear 18 of third motor 17
is connected to an operating shaft 126 by a worm gear 125, as shown in FIG. This operating shaft 1
26 utilizes the space between the lowermost cylinder parts 107c and 10d to attach the rear valve plate 112.
Spur gears 127 and 128 are disposed between the valve plate 111 and the valve plate 111 on the front side, and are attached to portions of the operating shaft 126 adjacent to the valve plates 111 and 112, respectively.

Reference numerals 129 and 130 are annular variable rings that constitute variable capacity members, and this variable ring 1
29 and 130 are disposed in the cylindrical space provided on the outer periphery of the cylinder portion 107 in the housings 105 and 106 so as to be concentric with the compressor drive shaft 101. This variable ring 129, 13
At zero, the rotational force of the operating shaft 126 is applied to the spur gears 127, 1
28 and variable rings 129, 130 through teeth 129a, 130a provided on the inner periphery.

Two bypass holes 131a and 131b are provided in the wall surface of each cylinder portion 107 at positions closest to the variable rings 129 and 130, and these bypass holes 131a and 131b are located on the inner periphery of the variable rings 129 and 130. Bypass grooves 132a and 132b provided in the circumferential direction on the surface, bypass grooves 133 arranged in parallel to the shaft 101 in the variable rings 129 and 130, and the variable ring 12
The inner peripheral surfaces of the compressors 9 and 130 communicate with a bypass port 135 formed in the housings 105 and 106 through a bypass groove 134 provided all around the center side of the compressor.
Furthermore, this bypass port 135 is connected to the housing 10.
5, 106 is formed so as to be electrically connected to the suction passage chamber 108 provided in the suction passage chamber 106.

In this embodiment, the bypass holes 131a and 131b raised in the wall surface of the cylinder 107 are arranged at positions that divide the cylinder volume into three equal parts, and either only the port 131b on the center side of the compressor, or both the ports 131a , 131b are arranged to face the bypass grooves 132a, 132b in accordance with the rotation angle of the variable rings 129, 130 (see FIGS. 10 and 11).

Further, the bypass grooves 132a, 132b are connected to the five cylinders 107a, 107b, 107c, 107.
d and 107e, respectively, as shown in FIG.
The cylinders 10 are provided with different lengths in the circumferential direction of the cylinders 30 and communicate with the suction passage chamber 108 according to the rotation angle of the variable rings 120 and 130.
It has been devised so that the number of 7s is different.

That is, in the case of this embodiment, when the rotation angle is 0°, all the bypass holes 131a and 131b (total 20
) is the bypass groove 1 of the variable rings 129, 130.
33, and the bypass groove 133, bypass groove 134 and housing 10
It is connected to the suction passage 108 through 5,106 bypass ports 135, and the cylinder volume that performs the net compression work is minimized.

When the rotation angle is 4 degrees, the cylinder 107
Only the bypass hole 131a provided in e is not in communication with the bypass groove 132a, and the remaining bypass holes 131a and 131b are both connected to the suction passage chamber 1.
It is electrically connected to 08. After that, the rotation angle is 8°, 12°,
..., as the temperature increases by 4 degrees, the suction passage chamber 10
When the rotation angle is 36 degrees, only the bypass hole 131b provided in the cylinder 107a is connected to the suction passage chamber 108 through the bypass groove 132b, and the others are not connected to the suction passage chamber 108. When there is no conduction and the rotation angle reaches 40 degrees, all bypass holes 131a and 131b are closed, and the cylinder volume for compressor work becomes maximum. The relationship between the rotation angle of the variable rings 129 and 130 and the cylinder volume that does the net compression work is shown in Figure 13, and the maximum capacity Vmax
The cylinder volume can be finely controlled in 10 steps between 1/3Vmax and 1/3Vmax.

Note that the rotational positions of the variable rings 129 and 130 can be detected as electrical signals by potentiometers of the position detection device 24.
That is, the worm gear 125 formed on the end surface of the operating shaft 126 is connected to the operating gear 241 of the position detection device 24.
The resistance value of the potentiometer of the position detection device 24 is varied according to the rotation of the operating shaft 126 (worm gear 125), and as a result, the resistance value of the potentiometer of the position detection device 24 is varied according to the position of the variable rings 129, 130. A fixed electrical signal is output.

The position detection device 24 is fixed to the side housing 110 with screws 243 via a stay 242 formed on an end surface thereof. Note that storage grooves are formed in the side housing 110 at the portion where the position detection device 24 is held and the portion where the servo motor 17 described above is held, so that the servo motor 17, the position detection device 24, etc. In addition to ensuring more secure retention, side housing 1
The servo motor 17 and the like are made not to protrude too much from the surface of 10. In addition, the servo motor 17,
The worm gears 18, 125, position detection device 24, etc. are covered with a cover (not shown) to prevent dust.

Next, the operation of only the 12 parts of the swash plate compressor will be explained.

The electromagnetic clutch 13 is connected and the shaft 101
When the swash plate 102 starts to rotate, the refrigerant gas vaporized in the evaporator 5 is transferred to the housings 105 and 106.
Suction passage chamber 1 is introduced from an inlet (not shown) provided in
08, valve plates 111, 112
It flows into the suction chamber 113 of the front and rear side housings 109, 110 through the suction side communication hole (not shown). When the piston 104, which reciprocates within the cylinder portion 107 as the swash plate 102 rotates, enters the suction stroke, the refrigerant gas is supplied to the elastic metal plate 11 from the suction ports in the valve plates 111 and 112.
5, 116 into the cylinder portion 107. Next, the piston 104
When the gas enters the compression stroke, the suction port is closed by the suction valve, and the refrigerant gas in the cylinder portion 107 is
It is compressed by the piston 104 and discharged into the discharge chamber 114 in the side housings 109, 110 through the discharge ports and discharge valves (not shown) of the valve plates 111, 112, and then the valve plate 1 is discharged again.
The refrigerant gas flows into the discharge passage chamber 114a in the housings 105, 106 from the unillustrated discharge side communication holes 11, 112, and then becomes high temperature and high pressure in the compression stroke of the piston 104.
It is sent to the condenser 2 from a discharge port 106 (not shown).

During the above operation, the rotational speed of the shaft 101 is varied according to the engine rotational speed, so the discharge capacity of the compressor 12 also increases or decreases depending on the engine rotational speed, and when the engine is at high rotational speed, etc. In this case, a situation may occur in which the discharge capacity of the compressor 20 becomes abnormally larger than the capacity required by the operating state of the refrigeration cycle. However, in the compressor 12 of the present invention, in such a state where the discharge capacity becomes excessive, the discharge capacity of the cylinder 107 is reduced to reduce the discharge capacity.

Therefore, the operation of the capacity control mechanism of the compressor 12 will be explained below.

The air temperature immediately after the evaporator is sensed by sensor 14, and the air temperature at the evaporator inlet side is sensed by sensor 2.
However, when the intake air temperature of the evaporator 5 rises and the cooling load increases, both sensors 1
The sensing temperature of sensors 4 and 23 rises and both sensors 14 and 2
The thermistor resistance values R ₁₄ and R ₂₃ of No. 3 decrease. As a result, the total series resistance Rs (= R ₁₄ + R ₂₃ + R ₂₄ )
decreases from the resistance value R ₁₅ of the setting resistor 15, and when V _A becomes smaller than (V ₂ - _{V C} ) in FIG. 6b (V _A < V ₂ + V _C ), the output 16 of the second comparator 162
2a is reversed from “Hi” level to “Lo” level,
Since transistor 165 is turned off, transistors 168, 169, and 170 are turned on.

At this time, as can be seen from the characteristics shown in FIG. 171 is off. As a result, the transistor 17 is connected to the servo motor 17.
0 emitter-collector and transistor 16
Current flows through the collector/emitter of 9.
Therefore, the servo motor 17 rotates in the forward direction, and is connected to the worm gear 125 and the operating shaft 1 via the worm gear 18.
26, spur gears 127, 128, and variable rings 129, 130 rotate clockwise in FIG.
Therefore, the variable ring 12 defined in FIG.
9,130 rotation angle increases and the net cylinder volume increases. Therefore, the compression function increases, and a cooling capacity corresponding to the cooling load is obtained. As the cooling capacity increases, the air temperature immediately after the evaporator gradually decreases.

As a result, the resistance value _R14 of the sensor 14 gradually increases as the air temperature decreases. At this time, the position detection device 24 also operates simultaneously with the rotation of the variable rings 129, 130, and its resistance value R ₂₄ increases, raising the potential V _A. As a result, when the potential V _A becomes larger than the reference potential V ₂ (V _A > V ₂ ), the output 162a of the second comparator 162 becomes "Hi" level,
Since transistor 165 is turned on, transistors 168, 169, and 170 are turned off. At this time, since the output 161a of the first comparator 161 is still at "Lo" level, the transistor 16
Nos. 6, 167, and 171 continue to be in the off state.
Therefore, the power to the servo motor 17 is cut off, the servo motor 17 stops, and the variable rings 129,1
The position No. 30 is held, and the compressor capacity is set according to the cooling load.

On the other hand, when the evaporator inlet air temperature decreases and the cooling load decreases, the air temperature immediately after the evaporator also decreases, causing the thermistor resistance of the sensors 14 and 23 to decrease.
Both R ₁₄ and R ₂₃ increase, and the potential V _A increases accordingly. Then, when the potential V _A becomes larger than the reference potential, that is, when V _A > V ₁ ,
The output 161a of the first comparator 161 goes from the "Lo" level to the "Hi" level, and the transistor 1
Since transistor 64a is turned on and transistor 164b is turned off, transistors 166, 167, and 171 are turned on.

As a result, the servo motor 17 has the emitter and collector of the transistor 171, and the transistor 1.
A current flows in the opposite direction to the above through the collector/emitter 67, causing the servo motor 17 to rotate in the opposite direction. This rotation is caused by the worm gear 125, operating shaft 126, spur gear 127,
128, and the variable rings 129, 130 rotate counterclockwise in FIG. As a result, the 12th
As the variable ring rotation angle in the figure decreases, the compressor capacity decreases.

As the compressor capacity decreases, the cooling capacity decreases, and as a result, the air temperature immediately after the evaporator increases. Therefore, the resistance _R14 of the sensor 14 decreases. At this time, the position detection device 24 is also activated and its resistance value _R24 decreases. The resulting total resistance
R _S decreases, and potential V _A also decreases. And the potential
When V _A decreases by a certain value V _C from the reference voltage V ₁ , that is, when V _A < (V ₁ − V _C ), the first comparator 1
Since the output 161a of the transistor 61 becomes "Lo" level and the transistor 164a is turned off, the transistor 164b is turned on and the transistors 166 and 16 are turned on.
7, 171 is turned off, the servo motor 17 stops again, and the positions of the variable rings 129, 130 are maintained.

In the above operation, the position detection device 24 constantly detects the rotational position of the variable rings 129, 130 and provides negative feedback to the input side of the control circuit 16, thereby preventing excessive rotation of the variable rings 129, 130. , servo motor 17, variable ring 129,
Prevents 130 hunting. Moreover, this also makes it possible to minimize overshoot and undershoot in evaporator temperature control.

In addition, in controlling the air temperature immediately after the evaporator, in addition to the air temperature immediately after the evaporator, the air temperature on the evaporator inlet side, which indicates the cooling load, is also sensed, so it is possible to respond to fluctuations in the cooling load. By controlling the capacity of the compressor 12, the evaporator temperature can be controlled more stably and accurately. In particular, in this example, the signal based on the air temperature immediately after the evaporator and the signal based on the air temperature on the evaporator inlet side, which indicates the cooling load, are processed in series, so the surface temperature of the evaporator changes depending on the cooling load. Temperature control will be performed while Generally, it is known that when the air temperature on the evaporator inlet side increases, freezing will be less likely to occur in the evaporator even if the evaporator surface temperature is lowered slightly, so in that case, lower the evaporator surface temperature slightly. Temperature control should be done accordingly. In particular, when the air temperature on the inlet side of the evaporator is high as described above, the cooling load is large, so controlling the temperature to lower the evaporator surface temperature is also convenient for controlling the air conditioner.

In an automotive air conditioner, the compressor 12 is driven by the engine for driving the vehicle, so the rotation speed of the compressor 12 fluctuates significantly as the driving conditions of the vehicle change, and this causes the refrigerant flow rate in the refrigeration cycle to change. This will result in a change in the amount. Therefore, in the present invention, in view of this point, the engine rotation speed is detected by the rotation detector 2.
5 and by inputting the output signal of this rotation detector 25 to the control circuit 16, the compressor capacity can be controlled in response to fluctuations in the engine rotation speed. In other words, as mentioned above, the output current of the rotation detector 25 increases as the engine rotation speed decreases, and decreases as the engine rotation speed increases, so if the engine rotation speed decreases, the potential at point A decreases (which is essentially the same as if R _S were decreased) and the compressor capacity increases. Conversely, if the engine speed increases, the potential at point A increases (which is substantially the same as increasing R _S ), and the compressor capacity decreases. In this way, by setting the compressor capacity according to the engine speed,
Control of compressor capacity is more stable with variable ring 1
There is no need to frequently move the rotational positions of 29 and 130, and the temperature of the evaporator can be smoothly controlled.

As described above, the compressor capacity is automatically controlled according to the operating status of the air conditioner, and is set to the optimal compressor capacity at that time. And sensor 1
4 is within the set temperature range (in the characteristic diagram of FIG. 6b, the potential difference of V ₁ - _{V 2} ), the servo motor 17 is de-energized and the positions of the variable rings 129 and 130 are changed. is maintained, and the compressor 12 continues to operate at a predetermined capacity.

When controlling the temperature of the air immediately after the evaporator to prevent freezing or frosting of the evaporator 5, it is preferable to control the compressor capacity so that the air temperature falls within a range of, for example, 3°C to 5°C.

As mentioned above, by setting a range in the set temperature and stopping the servo motor 17 while the air temperature immediately after the evaporator is within the set temperature range, it is possible to avoid severe fluctuations in cooling load and engine speed. However, the operating time of the servo motor 17 can be reduced. Therefore, its durability can be improved, and since the set temperature range can be arbitrarily selected by the variable resistor 163, stable control can be performed by changing the set range depending on the degree of load fluctuation, etc.

Furthermore, as mentioned above, since temperature control is performed by finely variable control of the compressor capacity, the electromagnetic clutch 1
3, the compressor 12 can be kept rotating without intermittent operation. As a result, it is possible to prevent deterioration in the durability of the clutch 13 and compressor 12 and deterioration in running feeling due to the disconnection of the electromagnetic clutch 13. Moreover, it is possible to prevent the deterioration of the feeling of cooling caused by the delay in connecting and connecting the electromagnetic clutch 13, and at the same time, there is no need to rotate the compressor 12 unnecessarily while maintaining its high capacity, resulting in overall power savings. Furthermore, in the conventional cooling capacity control that intermittents the compressor, the inside of the evaporator 5 immediately becomes overheated when the compressor is stopped, and even when the compressor is started again,
Effective cooling cannot be achieved until the overheated region is eliminated from the evaporator 5, and during that time the power to operate the compressor is essentially wasted.However, as in this example, cooling capacity can be controlled without stopping the compressor. In this case, the evaporator is not overheated as in the conventional case, so the compressor is not operated unnecessarily as described above.

In addition, in the above-mentioned embodiment, the bypass holes 131a and 131b of the cylinder 107 are connected to the bypass groove 132.
a, 132b, 133, 134, etc., but this communication destination may be any space as long as the pressure is lower than the internal pressure of the cylinder 107, in other words, the space where the internal pressure is the suction pressure. .
Further, depending on the shape of the compressor, this communication destination may be within the suction chamber 113, the crank chamber (rotation space of the swash plate 2), or another cylinder 107 in the suction stroke.

Further, in the above embodiment, a 10-cylinder swash plate compressor is used, but it goes without saying that any swash plate compressor having a plurality of cylinders may be used. Further, in the above embodiment, the variable ring 129,
130 is disposed in the cylindrical space on the outer periphery of the housings 105 and 106, but it goes without saying that it may also be disposed between the compressor drive shaft 101 and each cylinder 107.

Further, as long as the compressor 12 is of a variable capacity type, it is not limited to the swash plate type, and other types such as a vane type can be used.

In addition, the variable capacity members are variable rings 129, 13.
The configuration is not limited to 0, and can be changed to various configurations depending on the type of compressor, etc.

In addition to the servo motor 17, a combination of a negative pressure diaphragm mechanism and a link mechanism may be used as the drive device.

In addition, in the above example, the air temperature immediately after the evaporator was detected in order to detect the degree of cooling of the evaporator 5.
In addition to this, the evaporator surface temperature may also be detected.

In addition, a setting resistor 15 is provided on the control panel of the air conditioner so that the user can manually operate the setting resistor 15.
If the user is allowed to freely set the resistance value R ₁₅ of 5, the room temperature can be controlled by controlling the capacity of the compressor.

〔Effect of the invention〕

As explained above, in the present invention, in controlling the compressor capacity variable member, the first detected temperature detects the temperature on the evaporator outlet side, and the second detected temperature detects the temperature on the evaporator inlet side. Since the capacity of the compressor is controlled by the evaporator, high cooling capacity can be achieved in a region where the evaporator does not freeze, while taking into account the influence of the evaporator inlet temperature on the evaporator.
In addition, using a position detection signal that detects the operating position of the variable capacity member of the compressor, the first
The detected temperature signal and the second detected temperature signal are combined so that the combined value becomes constant, and the set temperature for preventing freezing of the evaporator is controlled to a predetermined temperature. The position of the variable capacity member can be controlled with high precision and without hunting.
Thereby, it is possible to improve the controllability of the compressor capacity and contribute to power saving.

[Brief explanation of drawings]

Fig. 1 is a refrigeration cycle diagram of a conventional automobile air conditioner, Fig. 2 is an electric circuit diagram showing the capacity control circuit of the device shown in Fig. 1, and Fig. 3 is a diagram showing the refrigerant pressure in the evaporator according to the conventional capacity control method. , a characteristic diagram showing the change in air temperature immediately after the evaporator, FIG. 4 is a configuration diagram showing the overall control system of the device of the present invention, and FIG. 5 is an electric circuit diagram illustrating the specific configuration of the control 16 of the device of the present invention. , FIG. 6a is an output characteristic diagram of the circuit 25b shown in FIG.
Figure b is an operating characteristic diagram of the comparators 161 and 162 shown in Figure 5, and Figure 7 is a sectional view showing an embodiment of the compressor used in the present invention, which has a shape along line D-D in Figure 8. show. FIG. 8 is a side view of the compressor. 9th
The figure is a sectional view taken along the line A-A in FIG. 7, showing the relationship between the bypass hole and the bypass groove of the variable ring. 10th
The figure is a diagram showing the positional relationship of each bypass groove provided in the variable ring, and is a sectional view taken along the line BB in FIG. 11. Fig. 11 is a sectional view taken along the line C-C in Fig. 10; Fig. 12 is a sectional view showing the shape of the bypass groove corresponding to each cylinder; Fig. 13 is the rotation angle of the variable ring and the net cylinder that performs compression work. FIG. 3 is an explanatory diagram showing the relationship with volume. 5... Evaporator, 8... Air blower, 11... Ventilation casing, 12... Compressor, 14, 23... Temperature sensor, 16... Control means, 17... Servo motor forming a drive device, 24... ...Position detector, 25...
...Rotation detector, 129, 130...Variable ring forming a variable capacity member.

Claims (1)

[Scope of Claims] 1. A variable displacement compressor that receives the driving force of an automobile engine via an electromagnetic clutch and has a built-in variable displacement member that changes the discharge displacement, and an evaporator connected to the suction side of this compressor. a first temperature sensing means that senses the air temperature immediately after the evaporator or the evaporator surface temperature as a first detected temperature signal; and a second temperature sensing means that senses the air temperature on the inlet side of the evaporator as a second detected temperature signal. temperature sensing means; a drive device that drives the variable capacity member of the compressor; a position detection means that detects the operating position of the variable capacity member of the compressor as an operating position signal; the first detected temperature signal; The variable capacity member of the compressor inputs the second detected temperature signal and the operating position signal, synthesizes these signals, and adjusts the variable capacity member of the compressor to a value set for preventing freezing of the evaporator based on the synthesized value. A refrigeration cycle device for an automobile, comprising: a control means for outputting a control signal for controlling the drive device to the drive device.