JPH0150607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to capacity control of a refrigeration cycle used in an automotive air conditioner.

A conventionally well-known automobile air conditioner has a vapor compression refrigeration cycle consisting of a compressor 1, a condenser 2, a receiver 3, an expansion valve 4, and an evaporator 5, as shown in FIG. Since it is driven by the automobile engine (not shown) through the clutch 7, as the engine speed increases, the compressor speed will increase. Therefore, when the compressor rotational speed increases or the cooling load decreases due to a drop in outside temperature, etc., the fin temperature of the evaporator 5, that is, the evaporation temperature of the refrigerant, decreases to below 0°C. If frost adheres to the fins or freezes, the amount of air blown by the blower 8 decreases, and the cooling capacity decreases. Therefore, in order to prevent this frosting phenomenon and control the temperature inside the vehicle, the air temperature immediately after the evaporator 5 is detected by a temperature sensor 6 such as a thermistor, and a control circuit 9 shown in FIG. 10
By opening and closing the contact 10a of the compressor 1, the electromagnetic clutch 7 of the compressor 1 is turned on and off, and by adjusting the operating time of the compressor 1, the evaporation temperature of the refrigerant is controlled, and the air temperature immediately after the evaporator is controlled. I'm trying to control it. However, in such a configuration, if the cooling load decreases or the rotational speed of the compressor 1 increases, the compression function becomes excessive, and the capacity of the refrigeration cycle exceeds the cooling load. , as shown in FIG. 3, the air temperature T immediately after the evaporator 5 decreases and becomes below the set temperature To at point c. 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. During this period (i.e., time I), the air temperature T further decreases and becomes considerably lower than the set temperature To. Then, when the control circuit 9 operates at point a and the clutch 7 is disengaged, the compressor 1 is stopped, the expansion valve 4 is closed, and the supply of liquid refrigerant to the evaporator 5 is stopped. Then, the pressure inside the evaporator ₅ increases, and the superheated region of the refrigerant increases.
The effective heat transfer area decreases. As a result, evaporator 5
Immediately after, the air temperature T rises rapidly and becomes equal to or higher than the set temperature To at point d. However, for the same reason as above, there is a time delay in the temperature sensor 6, so the air temperature T continues to rise until the point b where the control circuit 9 is activated. At point b, 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 the above operation is repeated,
The following problems occur.

(1) When the compressor is operating, 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 superheated region due to a shortage of liquid refrigerant inside the evaporator 5. Overall, power is wasted.

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

(3) When the clutch 7 is disengaged, the difference in torque acting on the friction surface of the clutch is large, which adversely affects the durability of the clutch.

(4) When the clutch 7 is engaged, a relatively large torque is applied to the engine, which causes a shock, etc., which deteriorates the running feeling.

The present invention was made in view of the above problems, and by using a compressor equipped with a variable capacity member, it is possible to prevent fluctuations in air temperature due to intermittent operation of the compressor and to improve the durability of the clutch, etc. This makes it possible to smoothly control the temperature of the evaporator and prevent a decrease in cooling capacity due to freezing of the evaporator body, for example. An object of the present invention is to provide a refrigeration cycle control device for an automobile that can appropriately maintain temperature control.

In order to achieve the above object, the present invention provides a variable capacity compressor that is driven by an automobile engine and includes a variable capacity member that changes the discharge capacity, and an evaporator that is connected to the suction side of this compressor. a temperature sensing means for sensing the air temperature or evaporator surface temperature immediately after the temperature sensing means; a rotation sensing means for sensing the rotational speed of the automobile engine; a driving device for driving the variable capacity member of the compressor; control means that inputs a detection signal and controls a variable capacity member of the compressor so that the temperature detected by the temperature sensing means does not fall below a predetermined temperature; and a correction means for correcting the control of the variable capacity member by the control means so as to reduce the discharge capacity of the compressor in accordance with the amount of increase in the displacement.

According to the configuration of the present invention, the temperature sensing means and the control means control the discharge capacity of the compressor so that the temperature of the air immediately after the evaporator or the surface temperature of the evaporator does not fall below a predetermined temperature. For example, freezing of the container is prevented.

On the other hand, the rotation detection means and the correction means correct the control of the discharge capacity by the control means so as to reduce the discharge capacity of the compressor in accordance with the amount of increase in the engine speed. Therefore, while maintaining the temperature control of the evaporator by the control means, changes in the amount of refrigerant discharged due to changes in the engine speed are suppressed, and changes in the compressor speed due to changes in the engine speed are suppressed. This prevents the amount of refrigerant discharged from changing and the temperature of the evaporator from changing. Therefore, since correction is performed according to the engine speed, which is a factor that changes the temperature of the evaporator, the temperature control of the evaporator is maintained with high responsiveness even to fluctuations in the engine speed.

The present invention will be described below with reference to 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, the 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 automotive air conditioner, and inside it is the evaporator 5 shown in FIG. 1 and a motor-driven 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 outlet side refrigerant circuit of the evaporator 5,
This compressor 12 is driven by an automobile engine via an electromagnetic clutch 13. 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. 14 is a temperature sensor consisting of a thermistor for sensing the air temperature immediately after the evaporator 5; 23 is a temperature sensor consisting of a thermistor for sensing the air temperature on the inlet side of the evaporator 5; 24 is a temperature sensor for the compressor 12; This is a position detection device that detects the position of the built-in variable capacitance member, and consists of a potentiometer that is linked to the movement of the variable capacitance 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.

On the other hand, 15 is a setting resistor that determines the control value of the air temperature immediately after the evaporator, and 16 is a control circuit to which signals from the above-mentioned elements 14, 15, 23, 24, and 25 are input. That is, the element 14,
23 and 24 are connected in series, the output of the rotation detector 25 is added to a connection point A between this series circuit and the setting resistor 15, and the potential at this connection point A is input to the control circuit 16. 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. 1
8 converts the driving torque of the servo motor 15 to the compressor 12.
This is a worm gear for transmitting power to the variable capacity member. 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 operating switch for the air conditioner, and 22 is an on-vehicle power battery.

FIG. 5 shows a specific example of the control circuit 16, which has two comparators 161 and 162 that receive as input the potential at the connection point A between the setting resistor 15 and the series circuit. 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 rotation speed increases, as shown in FIG. 6a. ing. The output voltage of the frequency-voltage conversion circuit 25b is converted into the magnitude of the collector current of the transistor 25d by a voltage-current conversion circuit consisting of an operational amplifier 25c, a transistor 25d, 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 increases as the engine speed increases. It is starting to decline.

FIG. 6b shows the operating characteristics of the control circuit 16. The control circuit 16 is configured to control the thermistor resistance value _R14 of the temperature sensor 14, the thermistor resistance value _R23 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. Now, for convenience of explanation, the amount of correction by the output of the rotation detector 25 will be ignored. The first comparator 161
Rs is the resistance value of the setting resistor 15. From R ₁₅ , the variable resistor 16
The resistance value of 3 increases by R ₁₆₃ , that is, Rs>
When R ₁₅ + R ₁₆₃ , the output 161a becomes “Lo”
level becomes “Hi” level, and conversely Rs becomes R ₁₅ +
When R is smaller than ₁₆₃ by a certain value Rc, that is, Rs
<(R ₁₅ + R ₁₆₃ )−Rc, the output 161a
is now returning to the "Lo" level rather than the "Hi" level.

On the other hand, the output 162a of the second comparator 162 changes from the "Lo" level to the "Hi" level when Rs= _R15 , and conversely, when Rs becomes smaller than _R15 by the constant value Rc, that is, Rs< _R15 . -Rc, the output 162a returns from the "Hi" level to the "Lo" level. Rc is a constant resistance value width due to the hysteresis characteristics of the first and second comparators 161 and 162.

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 and 9, the cylinder portion 107 is provided 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 sandwiched between them.
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).
A discharge chamber 114 is formed on the inner periphery of the suction chamber 113 at a position facing the piston 104 . This discharge chamber 114 is connected to the valve plates 111 and 112.
The housing 10 is connected to the housing 10 through a discharge side communication hole (not shown).
It communicates with the discharge passage chamber 114a (FIG. 9) of No. 5,106. 115, 116 are valve plates 11
1,112 and the housings 105, 106. A U-shaped elastic metal plate (not shown) is located at a position facing the piston 104 of the elastic metal plate 115, 116, and is made of an elastic metal such as spring steel. A notch is provided to form a suction valve. In addition, the housings 105 and 106, the side housing 10
9, 110 and the valve plates 111, 112 are integrally connected by a through bolt 117, and the through bolt 117 is connected to the suction passage chamber 10 in the housings 105, 106 to facilitate assembly.
It is designed to pass through 8.

118 and 119 are radical bearings using normal needle bearings, and the 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 04 is moved back and forth.

122 is a shaft seal, and the side housing 1 is 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 on the lowermost cylinder portions 107c and 107d to attach the valve plate 11 on the rear side.
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. 1
Reference numerals 29 and 130 are annular variable rings that constitute variable capacity members, and this variable ring 12
9,130 is housing 105,106,
It is disposed in a cylindrical space provided on the outer periphery of the cylinder portion 107 so as to be concentric with the compressor drive shaft 101 . The rotational force of the operating shaft 126 is applied to the variable rings 129, 130 through the spur gears 127, 128.
The rotation is transmitted through teeth 129a, 130a provided on the inner periphery of the variable rings 129, 130.

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 circumferential surfaces of the housings 9 and 130 communicate with a bypass port 135 formed in the housings 105 and 106 through a bypass groove provided all around the center side of the compressor. This bypass port 135 is connected to the housing 105, 10
It is formed so as to be electrically connected to the suction passage chamber 108 provided in 6.

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 129 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 (20 holes in total) are located so as to directly oppose the bypass grooves 133 of the variable rings 129 and 130, and the bypass grooves 133, It is connected to the suction passage chamber 108 via the bypass groove 134 and the bypass ports 135 of the housings 105 and 106, and the cylinder volume that performs the net compression work is minimized. When the rotation angle is 4 degrees, only the bypass hole 131a provided in the cylinder 107e is not in communication with the bypass groove 132a, and the remaining bypass holes 131a and 131b are both in communication with the suction passage chamber 108. ing. Thereafter, as the rotation angle increases by 4 degrees such as 8 degrees, 12 degrees, ..., the number of bypass holes that do not communicate with the suction passage chamber 108 increases one by one, and when the rotation angle is 36 degrees, the cylinder Bypass hole 1 provided in 107a
Only the bypass holes 131b are in communication with the suction passage chamber 108 via the bypass groove 132b, and the others are not in communication. When the rotation angle reaches 40 degrees, all the bypass holes 131a and 131b are closed, and due to compression work. The cylinder volume of is maximum. The relationship between the rotation angle of the variable rings 129 and 130 and the cylinder volume that performs net compression work is shown in Figure 13, and the cylinder volume is changed over 10 stages between the maximum volume Vmax and 1/3 Vmax. can be precisely controlled.

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 attached to the side housing 110 by a screw 2 through a stay 242 formed on the side surface thereof.
43. 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 holding, the servo motor 17 and the like are prevented from protruding too much from the surface of the side housing 110. Although not shown, the servo motor 17, worm gears 18, 125, position detection device 24, etc. are covered with a cover (not shown) to prevent dust.

Next, to explain the operation of only the swash plate compressor 12, when the electromagnetic clutch 13 is connected and the shaft 101 and the swash plate 102 begin to rotate, the refrigerant gas vaporized in the evaporator 5 is transferred to the housing 10.
It is introduced into the suction passage chamber 108 through an inlet (not shown) provided in the valve plate 11.
It flows into the suction chambers 113 of the front and rear side housings 109, 110 through suction side communication holes (not shown) No. 1,112. When the piston 104, which reciprocates in the cylinder portion 107 as the swash plate 102 rotates, enters the suction stroke, refrigerant gas is formed on the elastic metal plates 115, 116 from the suction ports in the valve plates 111, 112. The air is sucked into the cylinder portion 107 through the suction valve. Next, when the piston 104 moves to the compression stroke, the suction port is closed by the suction valve, the refrigerant gas in the cylinder portion 107 is compressed by the piston 104, and the refrigerant gas is compressed through the discharge ports of the valve plates 111, 112 and the discharge valve. (not shown) through the side housing 109,1
10 is discharged to the discharge chamber 114 in the housing 105, 106, and then the discharge passage chamber 1 in the housing 105, 106 is discharged again from the discharge side communication hole (not shown) of the valve plate 111, 112.
The refrigerant gas flows into the housing 14a and becomes high temperature and high pressure during the compression stroke of the piston 104.
The water is sent to the condenser 2 from unillustrated discharge ports 05 and 106.

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 the sensor 14, and the air temperature at the evaporator inlet side is sensed by the sensor 23, but the cooling load increases due to the rise in the intake air temperature of the evaporator 5. Then, the sensing temperatures of both sensors 14 and 23 rise, and the thermistor resistance values R ₁₄ and R ₂₃ of both sensors 14 and 23 increase.
decreases, and as a result, the aforementioned Rs (=R ₁₄ + R ₂₃ + R ₂₄ )
decreases from the resistance value R ₁₅ of the setting resistor 15, and when Rs becomes smaller than (R ₁₅ - Rc) in FIG. 6b (Rs<R ₁₅ - Rc), 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 in FIG. 6, the output 161a of the first comparator 161 is at "Lo" level,
Transistor 164a turns off and transistor 1
Since transistor 64b was on, transistor 16
6,167,171 are off. the result,
Current flows through the servo motor 17 through the emitter-collector of the transistor 107 and the collector-emitter of the transistor 169, and the servo motor 17 rotates in the forward direction.
7, 128, and variable rings 129, 130 rotate clockwise in FIG. 9, the rotation angle of variable rings 129, 130 defined in FIG. 12 increases, and the net cylinder volume increases. Therefore, the compression power increases and the air temperature immediately after the evaporator gradually decreases. As a result, the resistance value of the sensor 14
_R14 gradually increases, and at this time, the position detection device 24 also operates simultaneously with the rotation of the variable rings 129, 130, its resistance value _R24 increases, and as a result, Rs becomes larger than the resistance value R15 of the setting resistor ₁₅ . (Rs.
>R ₁₅ ), the output 162a of the second comparator 162 becomes "Hi" level, and the transistor 165 turns on, so the transistors 168, 169,
170 is turned off. At this time, the first comparator 16
Since the output 161a of the transistor 1 is still at the "Lo" level, the transistors 166, 167, and 171 continue to be in the off state. Therefore, the servo motor 17
The power is cut off, the servo motor 17 stops,
The positions of the variable rings 129 and 130 are maintained, and the compressor capacity is set according to the cooling load.

On the other hand, due to the decrease in the cooling load, the air temperature at the inlet of the evaporator and the air temperature immediately after the evaporator decrease, and the thermistor resistance values R ₁₄ and R ₂₃ of the sensors 14 and 23 increase, and Rs becomes the resistance value of the setting resistor 15. R ₁₅ and variable resistor 1
When the resistance value R ₁₆₃ of 63 becomes larger than the sum of R 163, that is, when Rs>R ₁₅ + R ₁₆₃ , the first comparator 161
The output 161a changes from the "Lo" level to the "Hi" level, turning on the transistor 164a and turning off the transistor 164b, turning on the transistors 166, 167, and 171. As a result, a current in the opposite direction flows through the servo motor 17 through the emitter and collector of the transistor 171 and the collector and emitter of the transistor 167, causing the servo motor 17 to rotate in the opposite direction, and passing through the worm gear 18 to the worm gear 125, Operating shaft 126, spur gears 127, 128, variable ring 12
9,130 rotates counterclockwise in FIG.
Since the variable ring rotation angle in Figure 2 is reduced, the compressor capacity is reduced. As a result, the air temperature immediately after the evaporator increases, and the resistance value _R14 of the sensor 14 decreases.
At this time, the position detection device 24 is also activated and its resistance value R ₂₄ decreases, resulting in Rs becoming (R ₁₅ +
R ₁₆₃ ) − Rc, that is, Rs < (R ₁₅ +
_R163 ) - Rc, the output 161a of the first comparator 161 becomes "Lo" level, and the transistor 164a turns off, so the transistor 164b
turns on, transistors 166, 167, 171
is turned off, the servo motor 17 stops again, and the positions of the variable rings 129 and 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.
By controlling the capacity of the compressor 12 in response to fluctuations in the cooling load, the evaporator temperature can be controlled more stably and accurately.

On the other hand, in an automobile air conditioner, the compressor 12
Because it is driven by a car engine,
The rotational speed of the compressor 12 changes significantly as the driving conditions of the vehicle change, which causes a change in the refrigerant flow rate of the refrigeration cycle. Therefore,
In view of this point, the present invention detects the engine rotation speed with the rotation detector 25, and inputs the output signal of this rotation detector 25 to the control circuit 16, thereby compressing the engine speed in response to fluctuations in the engine rotation speed. Machine capacity can be controlled. 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 Rs decreases) and the compressor capacity increases.
Conversely, if the engine speed increases, the potential at point A increases (this is substantially the same as when Rs increases), and the compressor capacity decreases. In this way, by setting the compressor capacity in accordance with the engine speed, the control of the compressor capacity becomes more stable, eliminating the need to frequently move the rotational positions of the variable rings 129 and 130, and improving the evaporator's performance. Temperature control can be performed smoothly.

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. 6, the resistance value range of _R163 ), the servo motor 17 is deenergized and
9,130 is maintained, and the compressor 12 continues to operate at a predetermined capacity.

When controlling the air temperature immediately after the evaporator to prevent frost in the evaporator 5, the compressor capacity may be controlled so that the air temperature falls within the 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, since the operating time of the servo motor 17 can be reduced and its durability improved, and the set temperature range can be arbitrarily selected using the variable resistor 163, stable control can be achieved by changing the set range according to the degree of load fluctuation, etc. can be done.

In addition, as mentioned above, temperature control is performed by finely variable control of the compressor capacity, so
The compressor 12 can be kept rotating without disconnecting the electromagnetic clutch 13 in a wide range of operating conditions of the air conditioner, and as a result, the clutch 13 and the compressor 1 can be kept rotating without disconnecting the electromagnetic clutch 13.
It is possible to prevent deterioration of durability and deterioration of running feeling as described in No. 2. Moreover, the electromagnetic clutch 1
It is possible to prevent the deterioration of the feeling of cooling caused by the delay in the intermittent operation of the compressor 12, 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 conventional cooling capacity control that intermittents the compressor, when the compressor is stopped, the inside of the evaporator 5 immediately becomes overheated, and even when the compressor is started again, the evaporator 5 remains in the overheated region until the overheated region is removed. During this time, the power to operate the compressor was essentially wasted, but with a system that controls the cooling capacity without stopping the compressor, as in the conventional method, the evaporation Since the compressor is not overheated, 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 the 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. ,
Depending on the shape of the compressor, this communication destination may be connected to the suction chamber 1.
13, 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.

As described above, according to the present invention, the air temperature immediately after the evaporator or the evaporator surface temperature is sensed, and the discharge capacity of the variable displacement compressor is controlled so that this temperature does not fall below a predetermined temperature. Since the rotation speed of the automobile engine that drives the compressor is sensed and the control of the discharge capacity according to the evaporator temperature is corrected according to this rotation speed, durability decreases due to intermittent use of the compressor. It is possible to prevent the feeling of cooling from deteriorating due to air temperature fluctuations and to reduce the power consumption of the compressor.

In addition, the temperature of the evaporator can be controlled smoothly to prevent the cooling capacity from decreasing due to freezing of the evaporator body, and it is also highly responsive to changes in engine speed, which is a factor in changing the evaporator temperature. The above temperature control of the evaporator can be maintained with

[Brief explanation of drawings]

Fig. 1 is a refrigeration cycle diagram of a conventionally well-known 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 refrigerant in an evaporator using a conventionally well-known capacity control method. A characteristic diagram showing changes in pressure and air temperature immediately after the evaporator, FIG. 4 is a block diagram showing the overall control system of the device of the present invention, and FIG. 5 illustrates a specific configuration of the control circuit 16 of the device of the present invention. Electric circuit diagram, FIG. 6a is an output characteristic diagram of the circuit 25b shown in FIG. 5, and FIG. 6b is the comparator 16 shown in FIG.
1,162, FIG. 7 is a sectional view showing an embodiment of the compressor used in the present invention, and D in FIG.
- Shown as a shape along line D. FIG. 8 is a side view of the compressor. FIG. 9 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. FIG. 10 is a diagram showing the positional relationship of the bypass grooves 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, and Fig. 13 is the rotation angle of the variable ring and the net cylinder that performs compression work. It is an explanatory view showing the relationship with volume. 5... Evaporator, 8... Air blower, 11... Ventilation casing, 12... Compressor, 14, 23... Temperature sensor, 16... Control circuit, 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 capacity compressor that is driven by an automobile engine and has a built-in capacity variable member that changes the discharge capacity, and an air temperature or temperature sensing means for sensing the surface temperature of the evaporator; rotation detection means for detecting the number of rotations of the automobile engine; a drive device for driving the variable capacity member of the compressor; and inputting a detection signal of the temperature sensing means; A control means for controlling a capacity variable member of the compressor so that the temperature detected by the temperature sensing means does not fall below a predetermined temperature; A refrigeration cycle control device for an automobile, comprising: a correction means for correcting control of the variable capacity member by the control means so as to reduce a discharge capacity of the compressor.