JPH0358924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacity control device for a refrigeration cycle used in an air conditioning system for automobiles and the like.

[Conventional technology]

A conventionally well-known automobile air conditioner has the above-mentioned compression type 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. It is driven by an automobile engine (not shown) via an electromagnetic clutch 7.

Therefore, when the compressor rotation 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, causing frost on the fins. The amount of air blown by the blower 8 decreases due to adhesion or freezing, and the cooling capacity decreases. Conventionally, in order to prevent such frost formation and to 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 the temperature is detected by a control circuit 9 shown in FIG. By opening and closing the contacts 10a of the relay 10,
By turning on and off the electromagnetic clutch 7 of the compressor 1 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.

In such a conventional configuration, when the cooling load decreases or the rotation speed of the compressor 1 increases, a state of excessive compression function occurs, 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 T ₀ at point C. However, the temperature sensor 6 has a control circuit 9 due to its heat capacity.
There is a time delay shown in Fig. 3 until the control circuit 9 is activated, and the control circuit 9 starts operating from point C.
Up to that point (i.e. during the aforementioned time), the air temperature T decreases further and becomes significantly lower than the setpoint temperature T ₀ . When the control circuit 9 operates at point a and the clutch 7 is disengaged, the compressor 1 stops and the expansion valve 4
is closed, and the supply of liquid refrigerant to the evaporator 5 is stopped. Then, the internal pressure P _L of the evaporator 5 increases and the superheated region of the refrigerant increases, so that the effective heat transfer area of the evaporator 5 decreases. As a result, the air temperature T immediately after the evaporator 5 rises rapidly, and becomes equal to or higher than the set temperature T ₀ at point a. However, for the same reason as mentioned above, since there is a time delay of the temperature sensor 6, 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.

[Problem to be solved by the invention]

In the conventional intermittent control of the electromagnetic clutch as described above, the following problems occur.

(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 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 becomes 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.

As mentioned above, intermittent control of the compressor depends on the stability of the air temperature on the evaporator outlet side, the durability of the electromagnetic clutch,
There were also issues to be resolved in terms of driving feel.

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. Through this control, it is possible to significantly reduce the power consumption of the compressor, prevent a decline in cooling capacity due to icing on the evaporator body, etc., and improve the feeling of cooling by eliminating fluctuations in air temperature caused by intermittent use of the compressor. Furthermore, it is an object of the present invention to improve the durability of clutches and the like.

In particular, the present invention sets the capacity control of the compressor to lower the air temperature immediately after the evaporator when the refrigerant temperature of the evaporator becomes high, thereby achieving high cooling capacity in a region where the evaporator does not freeze. The purpose is to do so.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a refrigeration cycle for an automobile is equipped with a compressor whose discharge capacity can be changed. That is, the compressor is provided with a variable capacity member that changes its discharge capacity, and this variable capacity member is driven by a drive device.

Then, a control signal is outputted to this drive device by the control means, so that the discharge capacity of the compressor is increased or decreased to a set value set for preventing freezing of the evaporator.

The control means also includes a first detection signal indicating the degree of cooling directly related to freezing of the evaporator.
The air temperature on the outlet side of the evaporator or the evaporator surface temperature is inputted by the sensing means. In addition, as a second detection signal related to the cooling capacity of the refrigeration cycle,
The second sensing means inputs refrigerant sensitivity or refrigerant pressure in the evaporator. Then, in the control means, the first and second detection signals are combined so that the combined value remains approximately constant even when one of the first and second detection signals becomes high and the other becomes low, and the above-mentioned drive device is controlled based on this combined value. control signal is output.

[Effect]

According to the above configuration of the present invention, the drive device is driven according to the control signal output from the control means,
By driving the variable capacity member by this drive device, the discharge capacity of the variable capacity compressor is changed.

The control means includes a first sensor that senses the degree of cooling of the evaporator.
and a second sensing means for sensing the cooling capacity of the evaporator.
Input the detection signal with the sensing means.

Then, a control signal is outputted to increase or decrease the discharge capacity of the compressor so that the combined value of these detection signals becomes the set value set for preventing freezing of the evaporator.

Here, the control means controls the capacity of the compressor so that the combined value of the two detection signals becomes the set value.
When one detection signal is high, the composite value becomes the set value when the other is low.

Therefore, when the refrigerant temperature or refrigerant pressure in the evaporator is low and icing is likely to occur, the capacity of the compressor is reduced so that the air temperature or surface temperature on the outlet side of the evaporator becomes high, thereby reliably preventing icing. .
Furthermore, the capacity of the compressor is controlled by inputting the detection signal of the air temperature or surface temperature on the outlet side of the evaporator, so even when the air temperature on the inlet side of the evaporator is high, the air temperature or surface temperature on the outlet side is higher than necessary. The capacity is controlled so that the air does not rise too high, and the air on the outlet side is sufficiently cooled.

Also, the refrigerant temperature or refrigerant pressure in the evaporator is high,
When freezing is difficult to occur, the capacity of the compressor is increased so that the air temperature or surface temperature on the outlet side of the evaporator is lowered, and the air on the outlet side is sufficiently cooled. Moreover, the compressor capacity is controlled by inputting the detection signal of the air temperature or surface temperature on the outlet side of the evaporator, so even when the air temperature on the inlet side of the evaporator is low, the air temperature or surface temperature on the outlet side is higher than necessary. The capacity is controlled so that it does not drop to the bottom, and icing is reliably prevented.

〔Example〕

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 side of the ventilation casing 11 communicates with an inside air intake port and an outside air intake port via an inside/outside switching box (not shown),
The other end communicates with an air outlet (an upper air outlet for cooling, a lower air outlet for heating, etc.) into the vehicle interior through a heater unit (not shown). A compressor 12 is connected to the refrigerant circuit on the outlet side of the evaporator 5, and this compressor 12 is driven by an automobile engine via an electromagnetic clutch 13. Furthermore, this compressor 12
As will be described later, the pump is constructed as a variable capacity type having a built-in variable capacity member that varies the discharge capacity. 1
4 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 temperature of the refrigerant flowing in the piping of the evaporator 5; Installed inside the entrance/exit piping. 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. 15 is a setting resistor for setting the control value of the sum of the air temperature immediately after the evaporator and the refrigerant temperature in the evaporator to a value that does not cause freezing in the evaporator;
6 is a control circuit, and each of the above-mentioned elements 14, 15, 23,
24 signals are input. That is, the above elements 14, 23, 24 are connected in series,
The potential at the connection point A between this series circuit and the setting resistor 15 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.

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. 20 is a control circuit, which controls the engine speed,
It senses the outside temperature, etc., and opens the relay contact 19 when this temperature drops. 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 16. The difference between the reference potentials V ₁ and V ₂ can be freely adjusted using the variable resistor 163. First comparator 1
Transistor 164 by output 161a of 61
a, 164b are turned on and off, and the second comparator 16
The transistor 165 is turned on and off by the output 162a of the transistor 2. 166 to 171 are transistors for driving the servo motor 17.

FIG. 6 illustrates the operating characteristics of the control circuit 16 in relation to the voltage at the connection point A. The control circuit 16 controls the thermistor resistance value R1 of the temperature sensor 14.
4, thermistor resistance value R23 of the temperature sensor 23, and potentiometer resistance value R2 of the position detection device 24.
4 in series with the total resistance R _S , and the position sensing device 15
The potential at the connection point A changes depending on the resistance value R15 of
The rotation of the servo motor 17 is controlled so that V _A is between the reference potentials V ₁ and V ₂ .

When the potential V _A of the first comparator 161 exceeds the reference potential V ₁ , its output 161a changes from the "Lo" level to the "Hi" level, and conversely, the potential V _A becomes the reference potential V1.
When V ₁ becomes smaller than V 1 by a certain value V _C , the output 1
61a 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 return 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, which is connected to an automobile engine serving as a drive source via an electromagnetic clutch 13 shown in FIG. 4 and a V-belt (not shown), and is rotated by the driving force of the engine. It is something. A swash plate 102 is fixed to the shaft 101 with a key and rotates together with the shaft 101. Rotation of the swash plate 102 causes a piston 104 to reciprocate via a shoe 103. 105 and 106 are housings, and the cylinder portion 10 supports the reciprocating movement of the piston 104.
7, and is 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 107a, 10
7b, 107c, 107d, and 107e are formed, and only the lowest cylinder parts 107c and 107d are spaced at an angle of 88°, and the spaces between the other cylinder parts are all 68°. ing. Further, the suction passage chamber 108 is formed between each cylinder part 107 as shown in FIG. It communicates with the outlet side refrigerant circuit. 10
Reference numerals 9 and 110 indicate side housings, and valve plates 11 are disposed outside the housings 105 and 106.
1 and 112, and a portion of the side housings 109 and 110 that directly communicates with the suction passage chamber 108 through suction side communication holes (not shown) of the valve plates 111 and 112. A suction chamber 113 is formed therein, and a discharge chamber 114 is formed in the side housings 109 and 110 at a position facing the piston 104 on the inner periphery of the suction chamber 113. This discharge chamber 114 is connected to the housings 105 and 1 through a discharge side communication hole (not shown) of the valve plates 111 and 112.
06 discharge passage chamber 114a (FIG. 9). 115, 116 are valve plates 111, 1
12 and the housings 105, 106, the piston 1 of the elastic metal plates 115, 116 is a disc-shaped elastic metal plate made of an elastic metal, for example, spring steel.
A U-shaped notch (not shown) is provided at a position facing 04 to form a suction valve. In addition, housings 105, 106, side housing 109,
110 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 within 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
Thrust bearings 20 and 121 are located between the center portions of the housings 105 and 106 and the swash plate 102, so that the force applied to the swash plate 102 in the thrust direction (axial direction), that is, the swash plate 102
This supports the reaction force received when 04 is communicated back and forth.

Reference numeral 122 denotes a shaft seal, which is located between the side housing 109 and the shaft 101, which are located on the drive source side (in other words, on the electromagnetic clutch 103 side) among the side housings 109 and 110, and seals the refrigerant gas and lubrication inside the compressor. It maintains airtightness to prevent oil from leaking 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 servo 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 107d to attach the rear valve plate 11.
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 forming variable capacity members, and the variable cylinder 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 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 drilled 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 107 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 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 directly opposite the bypass grooves 133 of the variable rings 129 and 130, and this bypass The suction passage chamber 108 is connected to the suction passage chamber 108 through the groove 133, the bypass groove 134, and the bypass port 135 of the housings 105, 106, so that the cylinder volume that performs the net compression work is minimized. When the rotation angle is 4°, 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, etc., 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,
Bypass hole 131 provided in cylinder 107a
Only the bypass hole 1 is connected to the suction passage chamber 108 through the bypass groove 132b, and the others are not connected.
31a and 131b are closed, and the cylinder volume for compression work is maximized. This variable ring 12
The relationship between the rotation angle of 9,130 degrees and the cylinder volume that performs net compression work is shown in Figure 13, and the cylinder volume is finely reduced in 10 steps between the maximum volume Vmax and 1/3. Can be controlled.

The rotational positions of the variable rings 129 and 130 can be detected as electrical signals by the potentiometer 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 operating shaft 126
The potentiometer resistance value of the position detection device 24 is varied in accordance with the rotation of the worm gear 125.
As a result, an electric signal determined depending on the position of the variable rings 129, 130 is output. The position detection device 24 is fixed to the side housing 110 with screws 243 via a stay 242 formed on the side 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. Also, although not shown,
Servo motor 17, worm gears 18, 125,
The position detection device 24 and the like 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 1 and swash plate 2 begin 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 flows through the valve plate 1.
Elastic metal plate 115 from the inlet in 11, 112,
The cylinder part 10 via a suction valve formed in 116
It gets sucked into 7. 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 valve plate 11
1,112 and a discharge valve (not shown) into the discharge chamber 114 in the side housings 109, 110, and then the valve plate 111,
The refrigerant gas flows into the discharge passage chamber 114a in the housings 105, 106 from the discharge side communication hole 112 (not shown), 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 (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 depending on the engine rotational speed, and when the engine is at high rotational speed. In some cases, the discharge capacity of the compressor 12 becomes abnormally larger than the capacity required by the operating state of the refrigerant 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 when the sensed temperature increases due to an increase in the cooling load, the thermistor resistance value R14 of the sensor 14 decreases, and the potential V _A decreases accordingly. As a result, in FIG. 6, when the potential V _A becomes smaller than (V ₂ − V _C ) (V _A <V ₂ − V _C ),
Since the output 162a of the second comparator 162 is inverted from the "Hi" level to the "Lo" level and the transistor 165 is turned off, the transistors 168 and 1
69,170 turns on. At this time, as can be seen from the characteristics in FIG. 6, the output 1 of the first comparator 161
61a is at “Lo” level, and transistor 1
Since transistor 64a is off and transistor 164b is on, transistors 166, 167, 17
1 is off. As a result, the servo motor 17
A current flows through the emitter-collector of the transistor 170 and the collector-emitter of the transistor 169, causing the servo motor 17 to rotate in the forward direction and passing through the worm gear 18 to the worm gear 12.
5. Since the operating shaft 126, the spur gears 127, 128, and the variable rings 129, 130 rotate clockwise in FIG. 9, the rotation angle of the 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 R14 of the sensor 14 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 the potential V _A rises. As a result, in FIG. 6, 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, and the transistor 165 turns on. transistor 1
68, 169, 170 are turned off. At this time, the output 161a of the first comparator 161 is still “Lo”
level, so transistors 166, 16
No. 7,171 continues to be off. Therefore,
The power supply to the servo motor 17 is cut off, the servo motor 17 is stopped, 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 a decrease in the cooling load (a decrease in the evaporator suction air temperature, etc.), the air temperature immediately after the evaporator decreases, the thermistor resistance value R14 of the sensor 14 increases, and the potential _{V A increases} . becomes larger than the reference voltage range V ₁ (V _A >V ₁ ), the output 161e of the first comparator 161 goes from the “Lo” level to the “Hi” level, and the transistor 164a
is turned on and transistor 164b is turned off, so transistors 166, 167, and 171 are turned on. 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,
Since the variable rings 129 and 130 rotate counterclockwise in FIG. 9 and the variable ring rotation angle in FIG. 12 decreases, the compressor capacity decreases. As a result, the air temperature immediately after the evaporator rises, and the resistance value R of the sensor 14 increases.
14 decreases, and at this time, the position detection device 24 also operates at the same time, its resistance value R24 decreases, and the potential V _A also decreases, and as a result, the potential V _A becomes equal to the reference electrode.
When V ₁ decreases to below a certain value V _C (V _A
<V ₁ −V _C ), the output 161a of the first comparator 161
becomes “Lo” level, and the transistor 164a
is turned off, transistor 164b is turned on, transistors 166, 167, and 171 are turned off, servo motor 17 is stopped again, and the positions of 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.

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 will vary significantly as the driving conditions of the vehicle change. Furthermore, since the condenser 2 is generally installed to receive cooling air from the driving of the automobile, the condenser capacity will also vary depending on changes in the driving conditions of the automobile. Therefore, although the driving conditions of the automobile become a disturbance factor for evaporator temperature control, there is a correlation between fluctuations in refrigerant flow rate due to fluctuations in compressor rotation speed, fluctuations in condenser capacity, etc., and refrigerant temperature in the evaporator section. . Therefore, in the present invention, focusing on this point, the refrigerant temperature in the evaporator section is sensed by the sensor 23, inputted to the control circuit 16, and combined with the air temperature immediately after the evaporator, and this combined value and the set value R15 are combined. By configuring to perform the comparison, it is possible to set the compressor capacity corresponding to both the air temperature immediately after the evaporator and the refrigerant temperature in the evaporator section.

The compressor capacity is controlled so that the set value is the combined value of the air temperature immediately after the evaporator and the refrigerant temperature in the evaporator section, so when the refrigerant temperature is low and tends to freeze, the combined value is set when the air temperature is high. When the refrigerant temperature is high and icing is difficult to occur, the combined value and the set value match when the air temperature is low, ensuring sufficient cooling while preventing icing. Sufficient cooling is provided.

This stabilizes the control of the compressor capacity, eliminates the need to frequently move the rotational positions of the variable rings 129 and 130, and allows smooth temperature control of the evaporator.

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 de-energized and the positions of the variable rings 129 and 130 are maintained. The compressor 12 continues to operate at a predetermined capacity.

When controlling the air temperature immediately after the evaporator to prevent frost (freezing) in the evaporator 5, the compressor capacity may be controlled 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, 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 also prevents the deterioration of the feeling of cooling caused by the delay in the intermittent operation of step 3.
At the same time, the compressor 12 does not needlessly rotate while maintaining its high capacity, resulting in overall power savings.
Furthermore, in the conventional cooling capacity control that intermittents the compressor, when the compressor is stopped, the inside of the evaporator 5 becomes overheated immediately, and even when the compressor is started again, the evaporator remains in an overheated state until the overheated region is removed from the evaporator. Effective cooling was not possible, and the power to operate the compressor was essentially wasted during that time. However, in this case, where cooling capacity is controlled without stopping the compressor, the evaporator Since the compressor does not become overheated, the compressor does not operate 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., to the suction passage chamber 108, but the communication destination may be any space where the pressure is lower than the internal pressure of the cylinder cylinder 107, in other words, any space where the internal pressure is the suction pressure. Depending on the shape of the compressor, this communication destination may be the suction chamber 113, the crank chamber (the rotation space of the swash plate 2), or the inside of the 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.

Further, in the above-described example, the temperature of the air immediately after the evaporator was detected as the temperature on the space side of the evaporator 5, but the surface temperature of the evaporator may also be detected. Furthermore, the evaporator refrigerant pressure may be detected instead of the evaporator refrigerant temperature.

〔Effect of the invention〕

As described above, according to the present invention, the capacity of the compressor driven by the engine installed in the vehicle is increased or decreased to prevent freezing of the evaporator, which causes significant temperature fluctuations and driving feeling due to the intermittent operation of the compressor. deterioration can be suppressed.

Moreover, the capacity is increased or decreased so that the combined value of the detection signal of the evaporator's refrigerant temperature or refrigerant pressure and the detection signal of the outlet air temperature or surface temperature of the evaporator is used as the set value for freezing prevention. Therefore, when the refrigerant temperature or refrigerant pressure is low and tends to freeze, freezing can be reliably prevented by increasing the outlet air temperature or surface temperature, and even if the air temperature on the inlet side of the evaporator fluctuates, the outlet air temperature or Since the capacity is controlled according to the surface temperature, insufficient cooling will not occur.

In addition, when the refrigerant temperature or pressure is high and is difficult to freeze, the outlet air temperature or surface temperature can be lowered to prevent insufficient cooling, and even if the air temperature on the inlet side of the evaporator fluctuates, the outlet Since the capacity is controlled according to the surface temperature, freezing does not occur.

As described above, according to the present invention, it is possible to prevent malfunctions caused by the intermittent operation of the compressor, and it is also possible to exert the maximum cooling capacity while reliably preventing freezing of the evaporator.

[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. The electrical circuit diagram, FIG. 6, shows the comparator 161,1 shown in FIG.
FIG. 7 is a sectional view showing an embodiment of the compressor used in the present invention, and shows the shape taken along the line D--D in FIG. 8. 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 diagram showing the positional relationship between the bypass grooves provided in the variable ring.
It is a developed view in the direction of arrow B. 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 detection device, 12
9,130...A variable ring forming a variable capacity member.

Claims (1)

[Scope of Claims] 1. A compressor 12 that is driven by an engine mounted on an automobile and sucks, compresses, and discharges refrigerant; A variable capacity member 129, 130 that changes the discharge capacity of this compressor; This variable capacity member an evaporator 5 connected to the suction side of the compressor to cool the intake air; and an evaporator 5 that detects the air temperature on the outlet side of the evaporator or the surface temperature of the evaporator to prevent freezing of the evaporator. a first sensing means 14 that outputs a first detection signal as a related signal; and a first sensing means 14 that senses refrigerant temperature or refrigerant pressure in the evaporator and outputs a second detection signal as a signal related to the cooling capacity of the refrigeration cycle. a second sensing means 23 that inputs the first and second detection signals, synthesizes these detection signals, and determines a set value for preventing icing of the evaporator based on the synthesized value; A refrigeration cycle control device for an automobile, comprising a control means 16 for outputting a control signal to the drive device to increase or decrease the discharge capacity of the compressor.