JP5260918B2 - Capacity control system for variable capacity compressor - Google Patents

Abstract

A system for controlling the capacity of a variable-capacity compressor comprises target intake pressure setting means for setting a target intake pressure, a capacity control valve having a solenoid and adapted for regulating the controlled pressure, intake pressure estimating means for calculating an estimated intake pressure which is an estimate of the intake pressure of when the discharge capacity of the variable-capacity compressor is assumed as a maximum value according to external information sensed by external information sensing means, and control current adjusting means for adjusting the control current supplied to the solenoid of the capacity control valve or a parameter relating to the control current according to the preset target intake pressure and the calculated estimated intake pressure.

Description

  The present invention relates to a capacity control system for a variable capacity compressor applied to an air conditioning system.

  For example, a reciprocating variable displacement compressor used in a vehicle air conditioning system includes a housing, and a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore are defined in the housing. A swash plate is tiltably connected to a drive shaft extending in the crank chamber, and a conversion mechanism including the swash plate converts the rotation of the drive shaft into a reciprocating motion of a piston disposed in the cylinder bore. The reciprocating motion of the piston performs the steps of sucking the working fluid from the suction chamber into the cylinder bore, compressing the sucked working fluid, and discharging the compressed working fluid into the discharge chamber.

The stroke length of the piston, that is, the discharge capacity of the compressor, becomes variable by changing the pressure (control pressure) of the crank chamber, and in order to control the discharge capacity, an air supply passage that connects the discharge chamber and the crank chamber is used. A capacity control valve is disposed, and a throttle is disposed in a bleed passage that connects the crank chamber and the suction chamber.
There is a suction pressure control for controlling the pressure of the suction chamber (suction pressure) as a control of the discharge capacity, and the capacity control valve for executing the suction pressure control has a solenoid and a feeling for sensing the suction pressure. Some have a built-in pressure device (see, for example, Patent Document 1). In the capacity control system of the variable capacity compressor using such a capacity control valve, the target suction pressure that is the target of the suction pressure is determined by the electromagnetic force of the solenoid, that is, the energization amount, so that the suction pressure approaches the target suction pressure. It is mechanically feedback controlled by a pressure sensor.

More specifically, the pressure sensor is configured using, for example, a bellows or a diaphragm. In the case of a pressure sensor using a bellows, a compression coil spring is arranged inside the bellows maintained at a vacuum or atmospheric pressure, and suction pressure acts on one end of the bellows from the outside. Therefore, the bellows of the pressure sensor tends to expand as the suction pressure decreases.
The valve body of the displacement control valve is arranged so that a pressing force generated when the bellows of the pressure sensor is extended acts together with the electromagnetic force of the solenoid. Then, the opening of the capacity control valve changes as the bellows expands and contracts so that the suction pressure converges to the target suction pressure determined in accordance with the energization amount of the solenoid.
Japanese Patent Laid-Open No. 10-2284

According to the capacity control system of the variable capacity compressor of the suction pressure control method, the cooling state of the passenger compartment or the like has reached the target value until the suction pressure reaches the target suction pressure, particularly immediately after the variable capacity compressor is started. If not, the variable capacity compressor operates at maximum discharge capacity. In this connection, this type of capacity control system has the following problems.
In order to make the suction pressure reach the target suction pressure, the energization amount of the solenoid of the capacity control valve is operated. For example, when lowering the suction pressure, the energization amount of the solenoid is instantaneously increased to a value determined based on the target suction pressure, thereby increasing the discharge capacity of the variable capacity compressor. That is, the capacity control system that controls the suction pressure is established based on the correlation existing between the energization amount of the solenoid and the target suction pressure.

  However, on the other hand, the variable capacity compressor has a mechanically determined maximum discharge capacity, and even if the solenoid is energized exceeding the energization amount (hereinafter referred to as the maximum capacity energization amount) at which the discharge capacity becomes the maximum discharge capacity, The discharge capacity does not increase beyond the maximum discharge capacity. That is, when the maximum discharge capacity is reached, there is no correlation between the discharge capacity and the energization amount, and the excess of the energization amount is wasted.

In the conventional capacity control system, the energization amount of the solenoid is determined based on the correlation with the target suction pressure without considering the maximum capacity energization amount. Therefore, until the suction pressure reaches the target suction pressure, the energization amount supplied to the solenoid exceeds the maximum capacity energization amount, and the power consumption of the capacity control valve is wasted.
Also, depending on the operating conditions of the vehicle or the air conditioning system, there is a case where it is not necessary to operate the variable capacity compressor at the maximum discharge capacity immediately after starting the variable capacity compressor, even in order to bring the suction pressure close to the target suction pressure. is there.

  For example, when the vehicle is traveling at a high speed, the rotational speed of the variable capacity compressor becomes very high, and the capacity of the variable capacity compressor increases. However, the capacity of the air conditioning system is limited by the overall configuration of the air conditioning system, in particular by the capacity of the evaporator. Therefore, even if the capacity of the variable capacity compressor is increased, the capacity of the variable capacity compressor cannot be fully utilized. Therefore, in such a case, when the variable capacity compressor operates at the maximum discharge capacity, there is a problem that power is wasted in the variable capacity compressor.

Furthermore, if the variable capacity compressor has a very high rotational speed and the heat load on the evaporator of the air conditioning system is very large, the load on the variable capacity compressor will be affected when the variable capacity compressor operates at the maximum discharge capacity. May become excessive, leading to a failure of the variable capacity compressor.
The present invention has been made based on the above-described circumstances, and one of its purposes is to provide a capacity control system for a variable capacity compressor in which the power consumption of the capacity control valve is reduced.

Another object of the present invention is to provide a capacity control system for a variable capacity compressor in which the power consumption of the variable capacity compressor is reduced.
Another object of the present invention is to provide a capacity control system for a variable capacity compressor that ensures the reliability of the variable capacity compressor.

In order to achieve the above object, according to the present invention, the present invention is applied to a variable capacity compressor inserted together with a radiator, an expander and an evaporator in a circulation path through which a refrigerant circulates to constitute a refrigeration cycle of an air conditioning system. In a capacity control system that adjusts the control pressure to bring the suction pressure closer to the target suction pressure, based on the external information detection means for detecting one or more external information and the external information detected by the external information detection means The target suction pressure setting means for setting the target suction pressure, a displacement control valve for adjusting the control pressure having a solenoid, and the external information detected by the external information detection means, A suction pressure estimating means for calculating an estimated suction pressure that is an estimated value of the suction pressure when the discharge capacity of the variable capacity compressor is assumed to be maximum; Based on the target suction pressure set by the pressure setting means and the estimated suction pressure calculated by the suction pressure estimation means, the control current supplied to the solenoid of the capacity control valve or a parameter related to the control current is adjusted. Control current adjusting means, and when the target suction pressure is lower than the estimated suction pressure, the control current adjusting means or the control current necessary for causing the suction pressure to reach the target suction pressure. A capacity control system for a variable capacity compressor is provided in which a control current supplied to the solenoid or a parameter related to the control current is made smaller than a parameter related to a current .

Good Mashiku, the control current adjusting means includes threshold setting means for setting a threshold value based on the said target suction pressure, when the threshold value is lower than the estimated suction pressure, the suction pressure reaches the threshold value compared to the parameters associated with the control current or the control current required for to reduce the parameters related to the control current or the control current supplied to the solenoid (claim 2).

Preferably, the control current adjusting means includes a threshold setting means for setting a threshold with the target suction pressure as a reference, and an index setting means for setting an index with the estimated suction pressure as a reference. Is lower than the control current required for the suction pressure to reach the threshold value or a parameter related to the control current, the control current supplied to the solenoid or the parameter related to the control current is reduced ( Claim 3 ).

Preferably, the threshold value is one of an upper limit value and a lower limit value of a variation range of the target suction pressure, and a difference between the target suction pressure and the threshold value changes according to the magnitude of the target suction pressure ( Claim 4 ).
Preferably, the threshold is the lower limit of the variation range of the target suction pressure, the indicator is an upper limit value of the variation range of the estimated suction pressure (claim 5).

Preferably, the control current adjusting means is a control necessary for the suction pressure to reach the estimated suction pressure or the indicator when the target suction pressure or the threshold is lower than the estimated suction pressure or the threshold. current or so that the following parameters associated with the control current, to reduce the parameters related to the control current or the control current supplied to the solenoid (claim 6).

Preferably, the external information detection means includes a rotation speed detection means for detecting a physical quantity related to the rotation speed of the variable capacity compressor, and the control current adjustment means is detected by the rotation speed detection means. when the physical quantity is a predetermined value or more, the variable discharge capacity of the capacity compressor to limit the parameters related to the control current or the control current supplied to the solenoid so as to be smaller than the maximum (claim 7) .

Preferably, the external information detecting means includes a thermal load detecting means for detecting a thermal load of the evaporator, and the control current adjusting means is configured to detect a heat load of the evaporator detected by the thermal load detecting means. The control current supplied to the solenoid or a parameter related to the control current is limited so that the discharge capacity of the variable capacity compressor becomes smaller than the maximum when the value is equal to or greater than a predetermined value (Claim 8 ).

Preferably, the suction pressure estimation means calculates the estimated suction pressure by substituting the external information detected by the external information detection means into an empirical formula indicating the relationship between the external information and the estimated suction pressure. (Claim 9 ).
Preferably, the external information detection means detects a discharge pressure detection means for detecting a discharge pressure which is a pressure of the refrigerant in any part of a discharge pressure region of the refrigeration cycle, and detects a thermal load of the evaporator. A thermal load detection means for detecting the superheat degree of the refrigerant at the outlet of the evaporator, and a rotation speed detection for detecting a physical quantity corresponding to the rotation speed of the variable capacity compressor. The suction pressure estimating means is detected by the discharge pressure detected by the discharge pressure detecting means, the thermal load of the evaporator detected by the thermal load detecting means, and detected by the superheat degree detecting means. Using an empirical formula showing the relationship between the suction pressure and the physical quantity related to the degree of superheat of the refrigerant, the physical quantity related to the rotational speed of the variable capacity compressor detected by the rotational speed detection means, It calculates the estimated suction pressure (Claim 10).

Preferably, the expander is a temperature automatic expansion valve that adjusts the flow rate of the refrigerant based on the temperature of the refrigerant at the outlet of the evaporator, and the superheat degree detection means is provided at the outlet of the evaporator. Means for detecting the temperature of the refrigerant or a physical quantity related to the temperature, and expander inlet pressure detection means for detecting the pressure of the refrigerant at the inlet of the expander, and the superheat degree detection means, The degree of superheat is detected based on the temperature of the refrigerant at the outlet of the evaporator or a physical quantity related to the temperature and the pressure of the refrigerant at the inlet of the expander (claim 11 ).

Preferably, the air conditioning system is applied to a vehicle, and the thermal load detecting means includes an outside air temperature sensor for detecting an outside air temperature, and an evaporator for detecting a voltage applied to a fan for the evaporator. comprising at least a fan voltage detection means (claim 12).
Preferably, the external information detecting means includes an evaporator target outlet temperature setting means for setting an evaporator target outlet air temperature which is a target of the temperature of the air flow immediately after passing through the evaporator, and the target suction pressure estimation The means sets the target suction pressure so that the temperature of the air flow immediately after passing through the evaporator approaches the evaporator target outlet air temperature set by the evaporator target outlet temperature setting means (claim 13 ).

Preferably, the capacity control valve receives the discharge pressure and counters the discharge pressure when the pressure of the refrigerant in any part of the discharge pressure region of the refrigeration cycle is the discharge pressure. The variable capacity compression has a valve body capable of opening and closing a valve hole in response to one of the suction pressure and the control pressure and electromagnetic force of the solenoid, and changing the control pressure by opening and closing the valve hole The external information detecting means includes a discharge pressure detecting means for detecting the discharge pressure, and the control current adjusting means includes a discharge pressure detected by the discharge pressure detecting means. based on said target suction pressure, the suction pressure is computed parameters relating to the control current or the control current required to reach the target suction pressure (claim 4).

Preferably, the variable capacity compressor is rotatably supported within the housing in which a discharge chamber, a crank chamber, a suction chamber, and a cylinder bore are defined, a piston disposed in the cylinder bore, and the housing. A drive shaft, a conversion mechanism including a variable tilt swash plate element that converts rotation of the drive shaft into reciprocating motion of the piston, an air supply passage communicating the discharge chamber and the crank chamber, and the suction chamber; and a bleed passage for communicating the crank chamber, the displacement control valve is interposed in one of the air supply passage and the bleed passage (claim 15).

In the capacity control system for a variable capacity compressor according to claim 1 of the present invention, the suction pressure estimation means assumes that the discharge capacity of the variable capacity compressor is maximum based on external information. The estimated suction pressure is calculated. Then, the control current adjusting means adjusts a control current supplied to the solenoid or a parameter related to the control current based on the target suction pressure and the estimated suction pressure. The variable capacity compressor adjusts the control current or a parameter related to the control current based on the target suction pressure and the estimated suction pressure, so that the variable capacity compressor can achieve the maximum discharge capacity. When operating at, excess control current supplied to the solenoid is reduced. As a result, according to this capacity control system, power consumption in the capacity control valve is reduced.
Specifically, when the target suction pressure is lower than the estimated suction pressure, the control current adjusting means supplies the solenoid with the control current necessary for reaching the target suction pressure or a parameter related to the control current. The control current to be performed or a parameter related to the control current is reduced. As a result, when the variable capacity compressor is operating at the maximum discharge capacity, excessive control current supplied to the solenoid is reduced, and power consumption in the capacity control valve is reduced.

In the capacity control system of the variable capacity compressor according to claim 2 , when the threshold value is lower than the estimated suction pressure, the control current adjusting means is related to the control current required for the suction pressure to reach the threshold value or the control current. The control current supplied to the solenoid or a parameter related to the control current is made smaller than the parameter. The threshold value is set in consideration of variations in the target suction pressure, for example. As a result, when the variable capacity compressor is operating at the maximum discharge capacity, excessive control current supplied to the solenoid is reduced, and power consumption in the capacity control valve is reduced.

In the capacity control system of the variable capacity compressor according to claim 3 , when the threshold value is lower than the index, the control current adjusting means sets the control current necessary for the suction pressure to reach the threshold value or a parameter related to the control current. In comparison, the control current supplied to the solenoid or a parameter related to the control current is reduced. The threshold value is set in consideration of, for example, variation in target suction pressure, and the index is set in consideration of, for example, variation in estimated suction pressure. Thereby, when the variable capacity compressor is operating at the maximum discharge capacity, the excessive control current supplied to the solenoid is reliably reduced, and the power consumption in the capacity control valve is reduced.

In the capacity control system of the variable capacity compressor according to claim 4 , the threshold value is one of an upper limit value and a lower limit value of a variation range of the target suction pressure, and a difference between the target suction pressure and the threshold value is a magnitude of the target suction pressure. It changes according to. In this capacity control system, when the threshold value is lower than the index, it is substantially determined that the variable capacity compressor is operating at the maximum discharge capacity, and the difference between the target suction pressure and the threshold value is the target suction pressure. The accuracy of the determination is improved by changing according to the size of. As a result, when the variable capacity compressor is operating at the maximum discharge capacity, excessive control current supplied to the solenoid is more reliably reduced, and power consumption in the capacity control valve is reduced.

In the capacity control system of the variable capacity compressor according to claim 5 , the threshold value is a lower limit value of the variation range of the target suction pressure, and the index is an upper limit value of the variation range of the estimated suction pressure. Thereby, when the variable capacity compressor is operating at the maximum discharge capacity, the excessive control current supplied to the solenoid is more reliably reduced, and the power consumption in the capacity control valve is reduced.
In the capacity control system of the variable capacity compressor according to claim 6 , the control current adjusting means controls necessary to reach the estimated suction pressure or index when the target suction pressure or threshold value is lower than the estimated suction pressure or index. The control current supplied to the solenoid or the parameter related to the control current is reduced so as to be equal to or lower than the current or the parameter related to the control current. This prevents excessive control current from being supplied to the solenoid when the variable capacity compressor is operating at the maximum discharge capacity, further reducing power consumption in the capacity control valve.

  In addition, the control current supplied to the solenoid or the parameter related to the control current is set so that the control current adjusting means is equal to or less than the control current necessary for reaching the estimated suction pressure or the index or the parameter related to the control current. By reducing the value, the variable capacity compressor can be reliably operated in the discharge capacity control state based on the maximum discharge capacity. As a result, according to this capacity control system, the power consumption of the variable capacity compressor is reduced, and the reliability of the variable capacity compressor is ensured.

In the capacity control system of the variable capacity compressor according to claim 7 , when the rotational speed of the variable capacity compressor is high, the discharge capacity of the variable capacity compressor becomes smaller than the maximum, so that the load on the variable capacity compressor is reduced. It is reduced. As a result, failure of the variable capacity compressor is prevented, and the reliability of the variable capacity compressor is improved. Further, since the discharge capacity of the variable capacity compressor becomes smaller than the maximum, the power consumption of the variable capacity compressor is reduced.

In the capacity control system of the variable capacity compressor according to claim 8 , when the heat load of the evaporator is high, the discharge capacity of the variable capacity compressor becomes smaller than the maximum, thereby reducing the burden on the variable capacity compressor. The As a result, failure of the variable capacity compressor is prevented, and the reliability of the variable capacity compressor is improved. Further, since the discharge capacity of the variable capacity compressor becomes smaller than the maximum, the power consumption of the variable capacity compressor is reduced.

In the capacity control system of the variable capacity compressor according to the ninth aspect , the estimated suction pressure is accurately calculated by calculating the estimated suction pressure by substituting external information into the empirical formula. As a result, the power consumption of the capacity control valve is accurately reduced.
In the capacity control system for a variable capacity compressor according to claim 10 , the suction pressure estimation means relates to the discharge pressure, the heat load of the evaporator, the degree of superheat of the refrigerant at the outlet of the evaporator, and the rotational speed of the variable capacity compressor. By calculating the estimated suction pressure based on the physical quantity, the suction pressure is accurately estimated. As a result, excessive control current supplied to the solenoid is reliably reduced, and power consumption in the capacity control valve is reduced.

12. The capacity control system for a variable capacity compressor according to claim 11 , wherein the superheat degree detection means is based on the temperature of the refrigerant at the outlet of the evaporator or a physical quantity related to the temperature and the pressure of the refrigerant at the inlet of the expander. By detecting the superheat degree, the superheat degree is accurately detected. As a result, the estimation accuracy of the suction pressure is further increased, the excessive control current supplied to the solenoid is surely reduced, and the power consumption in the capacity control valve is reduced.

The variable displacement compressor capacity control system of claim 12, the heat load detecting means, accurately detects the thermal load based at least on the outside air temperature Do及 beauty voltage evaporator fans. As a result, the suction pressure is accurately estimated by the suction pressure estimation means.
On the other hand, the outside air temperature sensor and the evaporator fan voltage detection means are not special means, and the configuration of the air conditioning system does not become complicated. As a result, according to this capacity control system, an excessive control current supplied to the solenoid is reliably reduced with a simple configuration, and power consumption in the capacity control valve is reduced.

In the capacity control system of the variable capacity compressor according to claim 13 , the temperature of the air flow immediately after passing through the evaporator approaches the evaporator target outlet air temperature, and the temperature control accuracy of the passenger compartment that is air-conditioned by the air conditioning system is high. improves.
In the capacity control system of the variable capacity compressor according to the fourteenth aspect , the suction pressure or the control pressure and the electromagnetic force of the solenoid act against the discharge pressure acting on the valve body. wide. As a result, the power consumption of the capacity control valve is effectively reduced immediately after starting the variable capacity compressor.

The variable capacity compressor to which the capacity control system of the variable capacity compressor of claim 15 is applied is a reciprocating type, and the stroke of the piston defined by the minimum inclination angle of the swash plate element can be set very small. For this reason, the minimum discharge capacity is very small, and the mechanical variable range of the discharge capacity is wide. Therefore, by applying the capacity control system according to the present invention to a reciprocating variable displacement compressor, an air conditioning system in which the variable displacement range of the variable displacement compressor is wide and the power consumption of the displacement control valve is reduced. Provided.

Hereinafter, the capacity control system A of the variable capacity compressor according to the first embodiment of the present invention will be described.
FIG. 1 shows a refrigeration cycle 10 of a vehicle air conditioning system to which a capacity control system A is applied. The refrigeration cycle 10 includes a circulation path 12 through which a refrigerant as a working fluid circulates. In the circulation path 12, the compressor 100, the radiator (condenser or gas cooler) 14, the expander 16, and the evaporator 18 are sequentially inserted in the flow direction of the refrigerant, and when the compressor 100 is activated, the compressor 100 The refrigerant circulates through the circulation path 12 in accordance with the discharge capacity of the refrigerant.

That is, the compressor 100 performs a series of processes including a refrigerant suction process, a suction refrigerant compression process, and a compressed refrigerant discharge process.
The radiator 14 has a function of cooling the refrigerant discharged from the compressor 100, and the cooled refrigerant is expanded by passing through the expander 16. The expanded refrigerant is vaporized in the evaporator 18, and the vaporized refrigerant is sucked into the compressor 100.

The evaporator 18 also constitutes a part of the air circuit of the vehicle air conditioning system, and the air flow passing through the evaporator 18 is cooled by taking heat of vaporization by the refrigerant in the evaporator 18. The vaporized refrigerant has a superheat degree at the outlet of the evaporator 18, but the superheat degree is substantially kept at a predetermined value by the expander 16.
More specifically, as shown in FIG. 2, the inflator 16 has a cylindrical casing 180, and an inlet port 180 a is formed on one end side of the casing 180. An outlet port 180b is formed at the center of the casing 180, and the inlet port 180a and the outlet port 180b communicate with each other through a valve hole 182 provided inside the casing 180. The valve hole 182 is opened and closed by the valve body 184 on the inlet port 180a side, and the urging force fs1 of the compression coil spring 185 acts on the valve body 184 in the valve closing direction.

  A recess 180c is formed on the other end side of the casing 180, and the recess 180c and the second port 180b communicate with each other through an insertion hole 186 extending coaxially with the valve hole 182. A transmission rod 188 is inserted through the insertion hole 186, and one end of the transmission rod 188 is connected to the valve body 184. An end cap 190 with a flange is fixed to the other end of the transmission rod 188, and a biasing force fs2 of a compression coil spring 192 disposed in the recess 180c acts on the end cap 190 in the valve closing direction. .

Further, a conical cover 196 is fixed to the other end of the casing 180 via a diaphragm 194. The diaphragm 194 is made of a thin metal plate having flexibility, and an airtight space defined by the diaphragm 194 and the cover 196 is filled with a filler 197 in a gas-liquid mixed state.
The end cap 190 comes into contact with the center portion of the diaphragm 194, and the pressure Pt inside the temperature sensing portion increases, whereby the valve body 184 is urged in the valve opening direction.

Further, a pressure equalizing path 180d is formed on the other end side of the casing 180, and the pressure equalizing path 180d communicates the gap between the other end of the casing 180 and the diaphragm 194 and the outside of the cover 196.
The expander 16 is fixed in the block 198, and an inlet-side channel 198a, an outlet-side channel 198b, and a temperature-sensitive channel 198c are formed in the block 198. The inlet port 180a of the expander 16 and the radiator 14 communicate with each other through the inlet-side flow path 198a, and the outlet port 180b of the expander 16 and the evaporator 18 communicate with each other through the outlet-side flow path 198b.

  Although the evaporator 18 and the compressor 100 communicate with each other through the temperature sensing path 198c, the cover 196 of the expander 16 is located in the temperature sensing path 198c. Accordingly, when the refrigerant flowing in the temperature sensing path 198c contacts the outer surface of the cover 196, the temperature of the filler 197 in the cover 196 becomes equal to the temperature of the refrigerant flowing in the temperature sensing path 198c. Further, the pressure of the refrigerant flowing through the temperature sensing path 198c, that is, the refrigerant pressure Pe at the outlet of the evaporator 18 acts on the outer surface of the diaphragm 194 through the pressure equalizing path 180d.

The above-described expander 16 is a temperature automatic expansion valve, and the diaphragm 194, the cover 196, and the filler 197 constitute a temperature sensitive part. The expander 16 senses the temperature of the refrigerant at the outlet of the evaporator 18 at the temperature sensing unit, and the refrigerant superheated SH at the outlet of the evaporator 18 has a predetermined value so that the superheat degree SH of the refrigerant passing through the expander 16 becomes a predetermined value. Adjust the flow rate.
Here, the straight line C1 in FIG. 3 shows the relationship between the refrigerant temperature and the pressure Pe at the outlet of the evaporator 18 (superheat characteristic) when the refrigerant pressure Pin at the inlet of the expander 16 is a predetermined constant value. ) And is determined by the structure of the inflator 16. A curve C2 indicates the relationship between the saturation temperature and the saturation pressure of the refrigerant (R134a), and the difference between the straight line C1 and the curve C2 in the horizontal axis direction corresponds to the degree of superheat SH of the refrigerant at the outlet of the evaporator 18. To do.

On the other hand, FIG. 4 shows the relationship between the refrigerant pressure Pin at the inlet of the expander 16 and the superheat degree SH of the refrigerant at the outlet of the evaporator 18 when the temperature of the temperature sensing portion of the expander 16 is constant. Show the relationship. 4 that the superheat degree SH of the refrigerant at the outlet of the evaporator 18 changes as the refrigerant pressure Pin at the inlet of the expander 16 changes.
In the expander 16, if the force in the valve opening direction acting on the valve body 184 is Fo and the force acting in the valve closing direction is Fc, Fo and Fc are expressed by equations (1) and (2), respectively. Is done. And the valve opening conditions of the expander 16 are shown by Formula (3).

Fo = (Pt−Pe) · Sd− (Pout−Pe) · Ser−fs2 (1)
Fc = fs1 + (Pin−Pout) · Sev (2)
Fo> Fc (3)
In Equations (1) and (2), Pout is the refrigerant pressure at the outlet of the expander 16, Sd is the effective area of the diaphragm 194, Sev is the seal area of the valve body 184, and Ser is the cross-sectional area of the transmission rod 188. It is. Further, Pt is the pressure inside the temperature sensing part as described above.

  Referring to FIG. 1 again, the compressor 100 to which the capacity control system A is applied is a variable capacity compressor, for example, a swash plate type clutchless compressor. The compressor 100 includes a cylinder block 101, and the cylinder block 101 is formed with a plurality of cylinder bores 101a. A front housing 102 is connected to one end of the cylinder block 101, and a rear housing (cylinder head) 104 is connected to the other end of the cylinder block 101 via a valve plate 103.

  The cylinder block 101 and the front housing 102 define a crank chamber 105, and a drive shaft 106 extends longitudinally through the crank chamber 105. The drive shaft 106 passes through an annular swash plate 107 disposed in the crank chamber 105, and the swash plate 107 is hinged to a rotor 108 fixed to the drive shaft 106 via a connecting portion 109. Accordingly, the swash plate 107 can tilt while moving along the drive shaft 106.

A portion of the drive shaft 106 extending between the rotor 108 and the swash plate 107 is provided with a coil spring 110 that urges the swash plate 107 toward the minimum inclination angle. A coil spring 111 that urges the swash plate 107 toward the maximum inclination angle is attached to a portion of the drive shaft 106 that extends between the swash plate 107 and the cylinder block 101.
The drive shaft 106 penetrates through a boss portion 102a protruding outside the front housing 102, and is connected to a pulley 112 as a power transmission device at the outer end of the drive shaft 106. The pulley 112 is rotatably supported by a boss portion 102a via a ball bearing 113, and a belt 115 is wound around a pulley of an engine 114 as an external drive source.

A shaft seal device 116 is disposed inside the boss portion 102a to block the inside and the outside of the front housing 102 from each other. The drive shaft 106 is rotatably supported by bearings 117, 118, 119, and 120 in the radial direction and the thrust direction. Power from the engine 114 is transmitted to the pulley 112, and can rotate in synchronization with the rotation of the pulley 112.
A piston 130 is disposed in the cylinder bore 101a, and a tail portion protruding into the crank chamber 105 is formed integrally with the piston 130. A pair of shoes 132 is disposed in a recess 130a formed in the tail portion, and the shoes 132 are in sliding contact with the outer peripheral portion of the swash plate 107 so as to be sandwiched therebetween. Therefore, the piston 130 and the swash plate 107 are interlocked with each other via the shoe 132, and the piston 130 reciprocates in the cylinder bore 101a by the rotation of the drive shaft 106.

  A suction chamber 140 and a discharge chamber 142 are defined in the rear housing 104, and the suction chamber 140 can communicate with the cylinder bore 101 a through a suction hole 103 a provided in the valve plate 103. The discharge chamber 142 communicates with the cylinder bore 101a through a discharge hole 103b provided in the valve plate 103. The suction hole 103a and the discharge hole 103b are opened and closed by a suction valve and a discharge valve (not shown), respectively.

  A muffler 150 is provided outside the cylinder block 101, and the muffler casing 152 is joined to a muffler base 101b formed integrally with the cylinder block 101 via a seal member (not shown). The muffler casing 152 and the muffler base 101b define a muffler space 154, and the muffler space 154 communicates with the discharge chamber 142 via a discharge passage 156 that passes through the rear housing 104, the valve plate 103, and the muffler base 101b.

  A discharge port 152a is formed in the muffler casing 152, and a check valve 170 is disposed in the muffler space 154 so as to block between the discharge passage 156 and the discharge port 152a. Specifically, the check valve 170 opens and closes according to the pressure difference between the pressure on the discharge passage 156 side and the pressure on the muffler space 154 side, and closes when the pressure difference is smaller than a predetermined value, and the pressure difference is predetermined. If it is larger than the value, it opens.

Accordingly, the discharge chamber 142 can communicate with the forward portion of the circulation path 12 via the discharge passage 156, the muffler space 154, and the discharge port 152a, and the muffler space 154 is intermittently connected by the check valve 170. On the other hand, the suction chamber 140 communicates with the return path portion of the circulation path 12 via a suction port 104 a formed in the rear housing 104.
A capacity control valve (electromagnetic control valve) 200 is accommodated in the rear housing 104, and the capacity control valve 200 is inserted in the air supply passage 160. The air supply passage 160 extends from the rear housing 104 to the cylinder block 101 through the valve plate 103 so as to communicate between the discharge chamber 142 and the crank chamber 105.

On the other hand, the suction chamber 140 communicates with the crank chamber 105 via the extraction passage 162. The extraction passage 162 includes a clearance between the drive shaft 106 and the bearings 119 and 120, a space 164, and a fixed orifice 103 c formed in the valve plate 103.
The suction chamber 140 is connected to the capacity control valve 200 independently of the air supply passage 160 through a pressure sensitive passage 166 formed in the rear housing 104.

  More specifically, as shown in FIG. 5, the capacity control valve 200 includes a valve unit and a solenoid unit. The valve unit has a cylindrical valve housing 202, and a valve hole 204 is formed in the valve housing 202. The valve hole 204 extends in the axial direction of the valve housing 202, and one end of the valve hole 204 is connected to the outlet port 206. The outlet port 206 passes through the valve housing 202 in the radial direction, and the valve hole 204 communicates with the crank chamber 105 via the outlet port 206 and the downstream portion of the air supply passage 160.

  A valve chamber 208 is defined on the solenoid unit side of the valve housing 202, and the other end of the valve hole 204 opens at the end wall of the valve chamber 208. A cylindrical valve body 210 is accommodated in the valve chamber 208, and the valve body 210 can move in the valve chamber 208 in the axial direction of the valve housing 202. When one end of the valve body 210 abuts against the end wall of the valve chamber 208, the valve body 210 can close the valve hole 204, and the end wall of the valve chamber 208 functions as a valve seat.

  An inlet port 212 is formed in the valve housing 202, and the inlet port 212 also penetrates the valve housing 202 in the radial direction. The inlet port 212 communicates with the discharge chamber 142 through the upstream portion of the air supply passage 160. The inlet port 212 opens at the peripheral wall of the valve chamber 208, and the discharge chamber 142 and the crank chamber 105 can communicate with each other through the inlet port 212, the valve chamber 208, the valve hole 204, and the outlet port 206.

  Furthermore, a pressure sensitive chamber 214 is defined in the valve housing 202 on the side opposite to the solenoid unit, and a pressure sensitive port 216 is formed on the peripheral wall of the pressure sensitive chamber 214. The pressure sensing chamber 214 communicates with the suction chamber 140 through the pressure sensing port 216 and the pressure sensing passage 166. An axial hole 218 is provided between the pressure sensitive chamber 214 and the valve hole 204, and the axial hole 218 extends coaxially with the valve hole 204.

  A pressure sensitive rod 220 is integrally and coaxially connected to the other end of the valve body 210. The pressure sensitive rod 220 extends through the valve hole 204 and the axial hole 218, and the tip of the pressure sensitive rod 220 protrudes into the pressure sensitive chamber 214. The pressure-sensitive rod 220 has a large-diameter portion on the distal end side, and the large-diameter portion of the pressure-sensitive rod 220 is slidably supported by the inner peripheral surface of the axial hole 218. Therefore, the airtightness between the pressure sensitive chamber 214 and the valve hole 204 is ensured by the large diameter portion of the pressure sensitive rod 220.

The end wall of the pressure sensitive chamber 214 is formed by a cap 222 that is press-fitted into the end of the valve housing 202, and the cap 222 has a stepped bottomed cylindrical shape. The cylindrical portion of the support member 224 is slidably fitted to the small diameter portion of the cap 222, and a forced release spring 226 is disposed between the bottom wall of the cap 222 and the support member 224.
A pressure sensor 228 is accommodated in the pressure sensing chamber 214, and one end of the pressure sensor 228 is fixed to the support member 224. Therefore, the cap 222 supports the pressure sensor 228 via the support member 224.

  The pressure sensor 228 has a bellows 230, and the bellows 230 can expand and contract in the axial direction of the valve housing 202. Both ends of the bellows 230 are hermetically closed by caps 232 and 234, and the inside of the bellows 230 is kept in a vacuum state (depressurized state). In addition, a compression coil spring 236 is disposed inside the bellows 230, and the compression coil spring 236 biases the caps 232 and 234 away from each other so that the bellows 230 extends.

The cap 234 of the pressure sensor 228 can come into contact with the pressure sensitive rod 220 via the adapter 238. When the pressure in the pressure sensitive chamber 214 decreases and the pressure sensitive device 228 expands, The valve body 210 is urged in the valve opening direction.
Note that the amount of press-fitting of the cap 222 to the valve housing 202 is adjusted so that the displacement control valve 200 performs a predetermined operation.

On the other hand, the solenoid unit has a cylindrical solenoid housing 240 coaxially connected to the valve housing 202, and a cylindrical fixed core 242 is disposed concentrically within the solenoid housing 240. One end portion of the fixed core 242 is fitted to the end portion of the valve housing 202 to partition the valve chamber 208 and supports the valve body 210 slidably.
A bottomed sleeve 244 is fitted into a portion extending from the center to the other end of the fixed core 242. A core housing space 248 is defined between the bottom wall of the sleeve 244 and the other end of the fixed core 242, and a movable core 246 is disposed in the core housing space 248. The movable core 246 is slidably supported by the sleeve 244 and can reciprocate in the axial direction of the solenoid housing 240.

  One end of a solenoid rod 250 extending in the fixed core 242 contacts the other end of the valve body 210, and the other end of the solenoid rod 250 is fixed integrally with the movable core 246. Accordingly, the valve body 210 moves in the valve closing direction in conjunction with the movable core 246. A compression coil spring 252 is disposed between the movable core 246 and the bottom wall of the sleeve 244, and the compression coil spring 252 always urges the valve body 210 in the valve closing direction via the movable core 246 and the solenoid rod 250. To do.

A solenoid 254 is disposed around the sleeve 244 while being wound around the bobbin 253. The solenoid housing 240, the fixed core 242 and the movable core 246 are all made of a magnetic material to form a magnetic circuit, while the sleeve 244 is made of a nonmagnetic stainless steel material.
Here, a radial hole 256 is formed at the root of the tip of the fixed core 242, and a communication hole 258 that connects the radial hole 256 and the pressure sensing chamber 214 is formed in the valve housing 202. Further, the inner diameter of the central portion and the other end portion of the fixed core 242 is larger than the outer diameters of the valve body 210 and the solenoid rod 250, and the central portion of the fixed core 242 is between the pressure sensing chamber 214 and the core housing space 248. And the inside of the other end part, it communicates via the radial hole 256 and the communication hole 258.

Accordingly, the pressure of the crank chamber 105 (crank pressure Pc) acts on one end surface of the valve body 210 as a force in the valve opening direction, while the pressure of the suction chamber 140 (suction pressure Ps) acts on the other end surface of the valve body 210. ) Acts as a force in the valve closing direction.
Note that by setting the area of the valve hole 204 equal to the cross-sectional area of the portion of the valve body 210 supported by the distal end portion of the fixed core 242, the opening and closing operation of the valve body 210 is performed in the valve chamber 208. The pressure, in other words, the pressure in the discharge chamber 142 (discharge pressure Pd) is not involved. In this case, the suction pressure control characteristic of the capacity control valve 200 is not affected by the discharge pressure Pd. As a result, as shown in FIG. 6 and Expression (4), the target value (target suction pressure Pss) of the suction pressure Ps to be controlled is uniquely determined based on the current (control current I) supplied to the solenoid 254. To be determined.

In Formula (4), F (I) is an electromagnetic force that acts on the movable core 246 by energizing the solenoid 254, and Sb is an effective area of the bellows. Further, fs3 is an urging force of the compression coil spring 252 and fs4 is an urging force of the compression coil spring 236 of the pressure sensor 228.
A control device 400A provided outside the compressor 100 is connected to the solenoid 254. When the control current I is supplied from the control device 400A to the solenoid 254, an electromagnetic force F (I) acts on the movable core 246. The movable core 246 is attracted toward the fixed core 242 by the electromagnetic force F (I), and thereby the valve body 210 is urged in the valve closing direction.

FIG. 7 is a block diagram showing a schematic configuration of the capacity control system A including the control device 400A.
The capacity control system A has external information detection means for detecting one or more external information, and the external information detection means is an evaporator temperature sensor as an evaporator target temperature setting means 401 and an evaporator outlet air temperature detection means. 402.

  The evaporator target temperature setting means 401 is a target value (evaporator) of the air temperature Te at the outlet of the evaporator 18 which is a target of discharge capacity control of the compressor 100, based on various external information including the passenger compartment temperature setting. The target outlet air temperature Tes) is set, and the set evaporator target outlet air temperature Tes is input to the control device 400A as one of the external information. The evaporator target temperature setting means 401 can be constituted by, for example, a part of an air conditioner ECU that controls the operation of the entire air conditioning system.

The evaporator temperature sensor 402 is installed at the outlet of the evaporator 18 in the air circuit (see FIG. 1) and detects the air temperature Te immediately after passing through the evaporator 18. The detected air temperature Te is input to the control device 400A as one piece of external information.
Further, the external information detection means includes discharge pressure detection means, and the discharge pressure detection means has a pressure sensor 403 that constitutes a part thereof. The discharge pressure detection means is a means for detecting the discharge pressure Pd that is the pressure of the refrigerant in the discharge chamber 142. The pressure sensor 403 is mounted on the inlet side of the radiator 14 (see FIG. 1), detects the refrigerant pressure (hereinafter referred to as a detected pressure Ph) at the part, and inputs the detected pressure to the control device 400A.

  The discharge pressure Pd and the detection pressure Ph are discharge pressures in the general sense of the pressure in the discharge pressure region of the refrigeration cycle 10. The discharge pressure region of the refrigeration cycle 10 refers to a region from the discharge chamber 142 to the inlet of the radiator 14. The high pressure region of the refrigeration cycle 10 refers to a region from the discharge chamber 142 to the inlet of the expander 16. The pressure sensor 403 only needs to be able to detect the refrigerant pressure at any part of the high-pressure region.

On the other hand, the suction pressure region of the refrigeration cycle 10 refers to a region extending from the outlet of the evaporator 18 to the suction chamber 140. The discharge pressure region and the high pressure region also include a cylinder bore 101a in the compression process, and the suction pressure region also includes a cylinder bore 101a in the suction process.
Further, the external information detection means includes an outside air temperature sensor 404 and a vehicle interior temperature sensor 405. The outside air temperature sensor 404 is disposed in the air intake portion of the vehicle and detects the temperature Ta of the outside air introduced into the air circuit of the vehicle air conditioning system. The vehicle interior temperature sensor 405 is installed in the vehicle interior and detects the temperature Tt of the air in the vehicle interior.

  Furthermore, the external information detection means includes an evaporator fan voltage detection means 406 and an inside / outside air switching door position detection means 407. The evaporator fan voltage detection means 406 detects the voltage Vf applied to the fan motor of the evaporator fan. The evaporator fan generates an air flow passing through the evaporator 18 in the air circuit of the vehicle air conditioning system, and the voltage Vf is an index of the amount of air blown by the evaporator fan.

  The inside / outside air switching door position detecting means 407 detects the position of the inside / outside air switching door. In the vehicle air conditioning system, the ventilation path in the air circuit is changed according to the position of the inside / outside air switching door, but the inside / outside air switching door position detecting means 407 detects the state As of the ventilation path. In other words, the inside / outside air switching door position detecting means 407 detects whether the vehicle air conditioning system is operating in the outside air introduction mode or the inside air circulation mode.

The inside / outside air switching door position detection means 407 can be configured using, for example, a position detection switch.
Further, the external information detection means includes a compressor rotation speed detection means for detecting the rotation speed Ncn of the compressor 100. The compressor rotation speed detection means has an engine rotation speed sensor 408 that detects the rotation speed of the engine 114, and the rotation speed of the engine 114 detected by the engine rotation speed sensor 408 is multiplied by a predetermined pulley ratio. The rotation speed Ncn of the compressor 100 can be detected.

  The configuration of the compressor rotation speed detection means is not particularly limited as long as the rotation speed Ncn of the compressor 100 can be detected based on a physical quantity related to the rotation speed Ncn of the compressor 100. For example, the rotational speed Ncn may be detected from the vehicle speed and the gear position. Further, the rotational speed Ncn may be detected based on information including the throttle opening (accelerator opening). The physical quantity related to the rotational speed Ncn of the compressor 100 includes the rotational speed of the compressor 100 itself.

400 A of control apparatuses are comprised by independent ECU (electronic control unit), for example, However, You may include in ECU for engines which controls operation | movement of the ECU for air conditioners or the engine 114. FIG. Further, the evaporator target temperature setting means 401 may be included in the control device 400A.
The control device 400A includes a pressure correction unit 410, a superheat degree calculation unit 412, and a suction pressure estimation unit 414.

The pressure correction means 410 constitutes a discharge pressure detection means together with the pressure sensor 403, and calculates the discharge pressure Pd by correcting the detection pressure Ph detected by the pressure sensor 403. The pressure correction unit 410 inputs the calculated discharge pressure Pd to the suction pressure estimation unit 414.
The reason why the detection pressure Ph is corrected in this manner is that the refrigerant pressure differs between the discharge chamber 142 and the inlet of the radiator 14 even in the same discharge pressure region, particularly when the heat load is large. It is. The discharge pressure Pd can be calculated by a function Pd = f (Ph) using the detected pressure Ph as a variable. The function f (Ph) can be obtained in advance.

  The superheat degree calculation means 412 is based on the refrigerant temperature at the outlet of the evaporator 18 or a physical quantity related to the temperature and the refrigerant pressure Pin at the inlet of the expander 16 or a physical quantity related to the pressure Pin. The degree of superheat SH is calculated. Specifically, the thermal load Q of the evaporator 18 and the circulation amount of the refrigerant can be used as the former physical quantity, and the detected pressure Ph detected by the pressure sensor 403 can be used as the latter physical quantity.

As will be described later, the thermal load Q of the evaporator 18 can be calculated based on, for example, the outside air temperature Ta, the vehicle interior temperature Tt, the evaporator fan voltage Vf, and the ventilation path state As.
The superheat degree SH is calculated based on the refrigerant pressure Pin at the inlet of the expander 16 or a physical quantity related to the pressure Pin, as shown in FIG. This is because it changes depending on the refrigerant pressure Pin at the inlet of the expander 16.

In other words, the superheat degree SH of the refrigerant at the outlet of the evaporator 18 can be calculated by the function SH = g (Ph, Q) having the detected pressure Ph and the thermal load Q as variables, and the pressure sensor 403 and the superheat degree calculation. The means 412 constitutes a superheat degree detection means. The function g (Ph, Q) can be obtained in advance.
Note that the degree of superheat SH depends on the pressure Pin at the inlet of the expander 16 as shown in FIG. 4 because the expander 16 is based on the relationship of the above-described equations (1) to (3). By operating. When the inlet pressure Pin of the expander 16, that is, the pressure in the high pressure region of the refrigeration cycle 10 changes, the force Fc in the direction of closing the valve body 184 changes and the superheat degree SH changes.

Then, the superheat degree calculating means 412 inputs the superheat degree SH detected by the calculation to the suction pressure estimating means 414.
A sensor that detects the temperature of the refrigerant at the outlet of the evaporator 18 may be used as the superheat degree detection means.
The suction pressure estimating means 414 assumes that the compressor 100 is operating at a mechanically determined maximum discharge capacity, and estimates the suction pressure Ps based on the external information detected by the external information detecting means. The estimated suction pressure Pse is calculated.

Specifically, the suction pressure estimation means 414 calculates the estimated suction pressure Pse by substituting the external information detected by the external information detection means into the empirical formula. The empirical formula shows the relationship between the external information and the suction pressure Ps, and can be obtained in advance by experiments. The empirical formula may be a map.
The empirical formula is preferably the discharge pressure Pd, the refrigerant supercooling degree SC at the inlet of the expander 16, the heat load Q of the evaporator 18, and the refrigerant superheating degree SH at the outlet of the evaporator 18, The relationship between the rotation speed Ncn of the compressor 100 and the suction pressure Ps is shown. The suction pressure Ps can be accurately estimated according to the empirical formula showing the relationship between the discharge pressure Pd, the supercooling degree SC, the thermal load Q, the superheating degree SH, the rotation speed Ncn, and the suction pressure Ps. For example, the empirical formula is represented by Pse = h (Pd, SC, Q, SH, Ncn).

The empirical formula can be rewritten by replacing the quantities included as variables in the formula with other quantities that are related to each.
For example, the heat load Q of the evaporator 18 is expressed by a function Q = i (Ta, Tt, Vf, As) having the outside air temperature Ta, the passenger compartment temperature Tt, the evaporator fan voltage Vf, and the ventilation path state As as variables. Can be calculated. That is, when the state As of the ventilation path is the outside air introduction mode, the heat load Q can be calculated using the outside air temperature Ta and the voltage Vf as variables. On the other hand, when the state As of the ventilation path is the inside air circulation mode, the thermal load Q can be calculated using the vehicle interior temperature Tt and the voltage Vf as variables.

Therefore, the estimated suction pressure Pse can also be calculated by the empirical formula: Pse = j (Pd, SC, Ta, Tt, Vf, As, SH, Ncn).
If the outside air and the humidity in the vehicle interior are known, the calculation accuracy of the heat load Q of the evaporator 18 is improved. Therefore, the external information detection means further includes an outside air humidity sensor and a vehicle interior humidity sensor, so that the outside air and the vehicle interior are included. The thermal load Q may be detected on the basis of the humidity.

Further, in the outside air introduction mode, when the vehicle speed Vs is equal to or higher than a predetermined value, the air volume of the evaporator 18 is affected by the vehicle speed Vs. For this reason, a vehicle speed sensor is further included in the external information detection means, and heat is generated by a function Q = k (Ta, Tt, Vf, Vs, As) including the outside air temperature Ta, the vehicle interior temperature Tt, the voltage Vf, and the vehicle speed Vs as variables. The load Q may be calculated.
Further, the supercooling degree SC of the refrigerant at the inlet of the expander 16 does not change greatly in the refrigeration cycle 10 using the expander 16 that is a temperature automatic expansion valve. Therefore, for example, it is sufficient to set an appropriate approximate value in advance and correct the approximate value with other known variables such as the discharge pressure Pd, the outside air temperature Ta, the voltage Vf, and the state As of the ventilation path. The supercooling degree SC can be calculated with high accuracy.

Therefore, the estimated suction pressure Pse can also be calculated by the empirical formula: Pse = 1 (Pd, Ta, Tt, Vf, As, SH, Ncn).
In summary, the suction pressure estimation means 414 has not only the empirical formula: Pse = h (Pd, SC, Q, SH, Ncn) but also a modified empirical formula: Pse = 1 (Pd, Ta, Tt, Vf, As, SH, Ncn) or the like can also be used to calculate the estimated suction pressure Pse.

  Therefore, in the present embodiment, the discharge pressure Pd, the outside air temperature Ta, the vehicle interior temperature Tt, the evaporator fan detected by the external information detection means, the discharge pressure detection means, the superheat degree detection means, and the compressor rotation speed detection means. By substituting the voltage Vf, the superheat degree SH, and the rotation speed Ncn of the compressor 100 into an empirical formula obtained in advance: Pse = 1 (Pd, Ta, Tt, Vf, As, SH, Ncn) The pressure Pse is calculated. In this case, the estimated value of the suction pressure Ps in a state where the compressor 100 is operated at the maximum discharge capacity can be estimated almost accurately while using the existing sensor as the external information detection means.

  As described above, since Pd = f (Ph) and SH = g (Ph, Q), the estimation is also made by the empirical formula: Pse = m (Ph, Ta, Tt, Vf, As, Ncn). The suction pressure Pse can be calculated. Also in this case, the estimated value of the suction pressure Ps in a state where the compressor 100 is operated at the maximum discharge capacity can be estimated almost accurately while using the existing sensor as the external information detecting means.

Further, the control device 400A includes a target suction pressure setting unit 420, a control signal limiting unit 422, and a solenoid driving unit 424.
The target suction pressure setting means 420 sets the target suction pressure Pss. The target suction pressure Pss is a target value of the suction pressure Ps that is a control target.
In this embodiment, the target suction pressure setting means 420 includes the evaporator outlet air temperature Te actually detected by the evaporator temperature sensor 402 and the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401. The target suction pressure Pss is set based on the deviation ΔT. That is, the target suction pressure setting means 420 sets the target suction pressure Pss so that the evaporator outlet air temperature Te approaches the evaporator target outlet air temperature Tes.

That is, for the target suction pressure setting means 420, the evaporator temperature sensor 402 and the evaporator target temperature setting means 401 respectively set the evaporator outlet air temperature Te as the external information and the evaporator target outlet air temperature Tes as its target value. External information detection means to be provided.
If the target suction pressure Pss is set, the control current I is determined as shown in FIG. 6 and the equation (4), so that the target suction pressure setting means 420 does not control the target suction pressure Pss. Setting the duty ratio as a parameter related to the current I or the control current I is included.

  For example, the target suction pressure setting means 420 can calculate the control current I in accordance with PI control or PID control. The calculated control current I may be limited within a predetermined upper and lower limit range. Then, the target suction pressure setting means 420 generates a signal (discharge capacity control signal) corresponding to the calculated control current I or a duty ratio as a parameter related to the control current I and inputs it to the control signal limiting means 422. To do.

  The estimated suction pressure Pse calculated by the suction pressure estimating means 414 is input to the control signal limiting means 422 together with the discharge capacity control signal. The control signal limiting unit 422 applies a predetermined limit to the discharge capacity control signal as necessary based on the discharge capacity control signal and the estimated suction pressure Pse. Then, the control signal limiting unit 422 inputs the discharge capacity control signal to the solenoid driving unit 424.

  Specifically, the control signal limiting unit 422 includes a threshold setting unit, and the threshold setting unit sets the threshold with reference to the target suction pressure Pss or the control current I calculated by the target suction pressure setting unit 420. The threshold value may be the target suction pressure Pss itself, but can be set in consideration of the variation range of the target suction pressure Pss. For example, the threshold value may be the upper limit value PssH or the lower limit PssL of the variation range of the target suction pressure Pss. The variation in the target suction pressure Pss is caused by a component dimensional tolerance during the production of the capacity control valve 200.

The difference between the upper limit value PssH or the lower limit value PssL and the target suction pressure Pss may be changed based on the magnitude of the control current I as shown in FIG.
Further, the control signal limiting unit 422 includes an index setting unit, and the index setting unit sets the index based on the estimated suction pressure Pse calculated by the suction pressure estimation unit 414. The index may be the estimated suction pressure Pse itself, but can be set in consideration of the variation range of the estimated suction pressure Pse. For example, the index may be the upper limit value PseH or the lower limit value PseL of the variation range of the estimated suction pressure Pse.

  Then, the control signal limiting unit 422 includes a comparison unit, and the comparison unit compares the threshold value with the index. When the threshold value is smaller than the index as a result of the comparison, the control signal limiting unit 422 determines whether the control current I supplied to the solenoid 254 or the duty ratio of the control current is the control current I or the control current corresponding to the threshold value. The discharge capacity control signal is changed so as to be smaller than the duty ratio of I. Then, the control signal limiting unit 422 inputs the changed discharge capacity control signal to the solenoid driving unit 424.

The control current I corresponding to the threshold is a current at which the reference value of the suction pressure Ps in the feedback control by the pressure sensor 228 becomes equal to the threshold when the control current I is supplied to the solenoid 254, in other words, This is a current required for the suction pressure Ps to reach the threshold value.
Preferably, as shown in FIG. 6, when the threshold value is smaller than the index, the control signal limiting unit 422 corresponds to the control current I supplied to the solenoid 254 or the duty ratio of the control current I corresponding to the index. The discharge capacity control signal is changed so that the control current Ii or the duty ratio is set.

As in the case of the threshold value, the control current Ii corresponding to the index is a current at which the reference value of the suction pressure Ps in the feedback control by the pressure sensor 228 becomes equal to the index when the control current I is supplied to the solenoid 254. In other words, the current is necessary for the suction pressure Ps to reach the index.
On the other hand, when the threshold value is equal to or larger than the index, the control signal limiting unit 422 does not change the discharge volume control signal and drives the discharge capacity control signal input from the target suction pressure setting unit 420 by solenoid driving. Input to means 424.

  The solenoid driving unit 424 supplies the control current I to the solenoid 254 based on the discharge capacity control signal and drives the capacity control valve 200. That is, the control signal limiting unit 422 and the solenoid driving unit 424 constitute a control current adjusting unit, and the control current adjusting unit is calculated by the target suction pressure Pss set by the target suction pressure setting unit 420 and the suction pressure estimation unit. Based on the estimated suction pressure Pse, the control current I supplied to the solenoid 254 of the displacement control valve 200 or a parameter related to the control current I is adjusted.

FIG. 8 shows the configuration of the solenoid driving means 424.
The solenoid driving means 424 includes a switching element 430. The switching element 430 is inserted in series with the solenoid 254 of the capacity control valve 200 in a power supply line extending between the power supply 450 and the ground. The switching element 430 can electrically connect and disconnect the power supply line, and the control current I is supplied to the solenoid 254 by PWM (pulse width modulation) at a predetermined drive frequency (for example, 400 to 500 Hz) by the operation of the switching element 430. Is done.

A diode 432 is connected in parallel with the solenoid 254 to form a flywheel circuit.
A predetermined drive signal is input to the switching element 430 from the control signal generating means 434, and the duty ratio in PWM is changed corresponding to this signal.
A current sensor 436 is inserted in the power supply line, and the current sensor 436 detects a control current I flowing through the solenoid 254. The current sensor 436 is not limited to an ammeter as long as it can detect a physical quantity corresponding to the control current I, and may be a voltmeter.

  The current sensor 436 inputs the detected control current I to the control current comparison / determination unit 438, and the control current comparison / determination unit 438 receives the control current I input as the discharge capacity control signal from the control signal limiting unit 422 and the current sensor. The control current I detected by 436 is compared. Then, the control current comparison determination unit 438 changes the drive signal generated by the control signal generation unit 434 so that the detected control current I approaches the input control current I based on the comparison result.

  That is, the solenoid driving means 424 adjusts the control current I supplied to the solenoid 254 by changing the duty ratio by PWM (pulse width modulation) at a predetermined driving frequency (for example, 400 to 500 Hz). The solenoid drive unit 424 detects the control current I flowing through the solenoid 254 and performs feedback control so that the detected control current I approaches the control current I input from the control signal limiting unit 422.

  When the solenoid driving means 424 adjusts the control current I with the duty ratio, the control signal limiting means 422 may calculate the duty ratio as a parameter related to the control current I. In this case, the control signal limiting means The discharge capacity control signal generated by 422 is a signal for causing the solenoid driving means 424 to supply the control current I at a predetermined duty ratio.

That is, the discharge capacity control signal may be a signal corresponding to the control current I or a signal corresponding to a parameter such as a duty ratio related to the control current I.
Hereinafter, the operation (usage method) of the above-described vehicle air conditioning system will be described.
FIG. 9 shows a main routine of a program executed by the control device 400A. The main routine is started when, for example, the engine key of the vehicle is turned on, and is stopped when the vehicle is turned off.

In the main routine, first, initial conditions are set (S10). Specifically, the control current I supplied to the solenoid 254 is set to an initial value I _0. During the initial value I ₀ is supplied, the displacement control valve 200 is in the open state, the capacity of the compressor 100 is the smallest volume that is mechanically determined. The initial value I ₀ may be zero.
When the capacity of the compressor 100 is minimum, the pressure difference before and after the check valve 170 is lower than a predetermined value, and the compressor 100 cannot discharge the refrigerant to the refrigeration cycle 10. For this reason, the refrigerant discharged from the cylinder bore 101a to the discharge chamber 142 with the minimum discharge capacity flows into the crank chamber 105 from the discharge chamber 142 via the air supply path 160, and then sucked from the crank chamber 105 via the extraction passage 162. Return to chamber 140. That is, when the capacity of the compressor 100 is minimum, the refrigerant circulates inside the compressor 100.

  After S10, it is determined whether or not the air conditioner switch (A / C) of the vehicle air conditioning system is on (S12). That is, it is determined whether or not the occupant is requesting cooling or dehumidification of the passenger compartment. When the air conditioner switch is off (in the case of No), the main routine returns to S10. When the air conditioner switch is on (Yes), a suction pressure control routine S14, which is a subroutine, is executed.

FIG. 10 is a flowchart showing details of the suction pressure control routine S14.
In the suction pressure control routine S14, the evaporator target outlet air temperature Tes which is the target of the discharge capacity control of the compressor 100 is set and read (S100), and the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 is read. Is read (S102).
Then, a deviation ΔT between the evaporator target outlet air temperature Tes and the actual evaporator outlet air temperature Te is calculated (S104). Based on the calculated deviation ΔT, the control current I is calculated by, for example, a predetermined calculation formula for PI control (S106).

Incidentally, in the equation of S106, but it contains the control current I, the initial value of the control current I is I _0. Each time the suction pressure control routine S14 is executed once, the deviation ΔT is calculated in S104, and the subscript n of the deviation ΔT in the calculation formula of S106 is that the deviation ΔT is calculated in this S104. Indicates. Similarly, the subscript n-1 indicates that the deviation ΔT has been calculated in the previous S104.

Here, as described above, if the control current I is determined, the target suction pressure Pss can be uniquely determined. Therefore, calculating the control current I in S106 sets the target suction pressure Pss. Equivalent to.
Thereafter, it is determined whether or not the calculated control current I is equal to or greater than a preset lower limit I1 (S108). If the determination result in S108 is No, the lower limit I1 is read as the control current I (S110). If the determination result in S108 is Yes, it is compared and determined whether or not the calculated control current I is equal to or less than a preset upper limit value I2 (S112). If the determination result in S112 is No, the upper limit value I2 is read as the control current I (S114).

Accordingly, the control current I calculated in S106 is maintained as it is if it is not less than the lower limit value I1 and not more than the upper limit value I2, and is otherwise replaced with the lower limit value I1 or the upper limit value I2.
On the other hand, in the suction pressure control routine S14, a threshold is set based on the target suction pressure Pss set in S106 (S116). In the present embodiment, for example, the lower limit value PssL of the variation range of the target suction pressure Pss is set as the threshold value.

  Further, based on the external information detected by the external information detection means, an estimated suction pressure Pse that is an estimated value of the suction pressure Ps when the compressor 100 is operating at the maximum capacity is calculated ( S118). Then, an index is set based on the calculated estimated suction pressure Pse. In the present embodiment, for example, the upper limit value PseH of the variation range of the estimated suction pressure Pse is set as an index (S120).

Thereafter, it is determined whether or not the threshold value is equal to or greater than the index (S122). If the determination result in S122 is Yes, the control current I calculated in S106 or the control current I replaced with the lower limit value I1 or the upper limit value I2 is output (S124).
If the determination result in S122 is No, the control current Ii corresponding to the index set in S120 is calculated, and the calculated control current Ii is read as the control current I (S126). Then, the control current I read in S126 is output in S124. The solenoid driving unit adjusts the control current I actually supplied to the solenoid 254 so as to approach the control current I output in S124.

Thus, when the air conditioner switch is on, a control current I larger than the initial value I ₀ is supplied to the solenoid unit 254 of the capacity control valve 200. The electromagnetic force F (I) generated by the control current I closes the capacity control valve 200 with a valve opening corresponding to the control current I. As a result, the air supply passage 160 between the discharge chamber 142 and the crank chamber 105 is intermittently or continuously interrupted, and the crank pressure Pc decreases. In particular, immediately after the air conditioner switch is switched from the off state to the on state, in other words, immediately after the start of the compressor 100, the air supply passage 160 is cut off substantially continuously, and the crank pressure Pc decreases to the suction pressure Ps. To do.

  As the crank pressure Pc as the control pressure decreases, the inclination angle of the swash plate 107 increases and the stroke of the piston 130 increases. In particular, immediately after the air conditioner switch is turned on, the discharge capacity of the compressor 100 becomes maximum. As a result, when the pressure in the discharge chamber 142 increases and the differential pressure across the check valve 170 exceeds a predetermined value, the check valve 170 is opened and refrigerant is discharged from the compressor 100.

  According to the capacity control system A described above, even if the target value of the suction pressure Ps is set to the target suction pressure Pss, if the threshold value is lower than the index in the determination result of S122, the control current Ii corresponding to the index is controlled. The current I is supplied to the solenoid 254. With reference to the relationship between the control current I and the target suction pressure Pss in FIG. 6, the suction pressure Ps approaches the index by supplying the control current Ii to the solenoid 254.

Since the suction pressure Ps gradually decreases while the suction pressure control routine S14 is repeated, the estimated suction pressure Pse and the index gradually decrease. Finally, in the determination result of S122, the threshold value is equal to or greater than the index.
When the threshold value is equal to or greater than the index, the control current I corresponding to the target suction pressure Pss is supplied to the solenoid 254. When the control current I is supplied to the solenoid 254, the suction pressure Ps approaches the target suction pressure Pss. When the suction pressure Ps approaches the target suction pressure Pss, the pressure sensor 228 expands and contracts to maintain the suction pressure Ps at the target suction pressure Pss. As a result, since the discharge capacity is controlled so that the evaporator outlet air temperature Te approaches the evaporator target outlet air temperature Tes, the temperature of the passenger compartment is controlled with high accuracy and the comfort of the passenger compartment is ensured. Is done.

In the capacity control system A described above, the control signal limiting means 422 constituting the control current adjusting means has the control current I or the control current required for the suction pressure Ps to reach the threshold when the threshold is lower than the index. The control current supplied to the solenoid 254 or the parameter related to the control current is made smaller than the related parameter.
Specifically, in the capacity control system A, when the threshold value is lower than the index, the control current adjusting means controls the solenoid 254 to be supplied up to the control current Ii necessary for the suction pressure Ps to reach the index. The parameter related to the current I or the control current I is reduced. Thereby, referring to FIG. 6, the control current I is reduced by ΔI. As a result, in the capacity control system A, when the compressor 100 is operating at the maximum discharge capacity, an excessive control current I is prevented from being supplied to the solenoid 254, and the power consumption in the capacity control valve 200 is reduced. Reduced.

  In the conventional capacity control system, the excessive control current I is supplied to the solenoid only by the target suction pressure Pss without considering that the variable capacity compressor has a mechanically determined maximum discharge capacity. This is because the control current I has been determined based on this. That is, it has not been considered that even if the solenoid is energized exceeding the maximum capacity energization amount at which the discharge capacity becomes the maximum discharge capacity, the discharge capacity does not increase beyond the maximum discharge capacity.

On the other hand, the capacity control system A prevents the supply of the control current I beyond the maximum capacity energization amount by adjusting the control current I based on the target suction pressure Pss and the estimated suction pressure Pse. Thus, power consumption in the capacity control valve 200 is reduced.
Further, in the capacity control system A, the suction pressure estimation means 414 has the discharge pressure Pd detected by the discharge pressure detection means, the superheat degree SH detected by the superheat degree detection means, and the outside air detected by the outside air temperature sensor 404. The temperature Ta, the vehicle interior temperature Tt detected by the vehicle interior temperature sensor 405, the voltage Vf detected by the evaporator fan voltage detection means 406, and the state of the ventilation system detected by the inside / outside air switching door position detection means 407 By calculating the estimated suction pressure Pse based on As and the compressor speed Ncn detected by the engine speed sensor 408, the suction pressure Ps is accurately estimated.

On the other hand, the discharge pressure detecting means, the outside air temperature sensor 404, the inside temperature sensor 405, the evaporator fan voltage detecting means 406, the inside / outside air switching door position detecting means 407 and the engine speed sensor 408 are not special means, and are not air conditioning systems. The configuration of the system is not complicated.
As a result, according to the capacity control system A, the excessive control current I supplied to the solenoid 254 is reliably reduced with a simple configuration, and the power consumption in the capacity control valve 200 is reduced.

  In the capacity control system A, the superheat degree detection means calculates the superheat degree SH based on the refrigerant pressure Pin at the inlet of the expander 16, thereby further improving the estimation accuracy of the superheat degree SH and thus the estimated suction pressure Pse. Get higher. Thereby, the excessive control current I supplied to the solenoid 254 is reliably reduced with a simple configuration, and the power consumption in the capacity control valve 200 is reduced.

  The compressor 100 to which the capacity control system A is applied is a reciprocating type, and the stroke of the piston 130 defined by the minimum inclination angle of the swash plate 107 can be set very small. For this reason, the minimum discharge capacity is very small, and the mechanical variable range of the discharge capacity is wide. Therefore, if the capacity control system A is provided in the compressor 100, an air conditioning system in which the variable range of the discharge capacity of the compressor 100 is wide and power consumption is reduced can be provided.

The capacity control system B according to the second embodiment of the present invention will be described below.
The capacity control system B controls the discharge capacity of the compressor 100 using a capacity control valve 300 shown in FIG. 11 instead of the capacity control valve 200.
More specifically, the capacity control valve 300 includes a valve unit and a drive unit that opens and closes the valve unit. The valve unit has a cylindrical valve housing 301, and an inlet port (valve hole 301 a) is formed at one end of the valve housing 301. The valve hole 301 a communicates with the discharge chamber 142 via the upstream portion of the air supply passage 160 and opens to the valve chamber 303 defined inside the valve housing 301.

A cylindrical valve body 304 is accommodated in the valve chamber 303. The valve body 304 can move in the valve chamber 303 in the axial direction of the valve housing 301, and can close the valve hole 301 a by contacting the end face of the valve housing 301. That is, the end surface of the valve housing 301 functions as a valve seat.
Further, an outlet port 301 b is formed on the outer peripheral surface of the valve housing 301, and the outlet port 301 b communicates with the crank chamber 105 through a downstream portion of the air supply passage 160. The outlet port 301b also opens into the valve chamber 303, and the discharge chamber 142 and the crank chamber 105 can communicate with each other through the valve hole 301a, the valve chamber 303, and the outlet port 301b.

The drive unit has a cylindrical solenoid housing 310, and the solenoid housing 310 is coaxially connected to the other end of the valve housing 301. The open end of the solenoid housing 310 is closed by an end cap 312, and a solenoid 316 wound around a bobbin 314 is accommodated in the solenoid housing 310.
Further, a concentric cylindrical fixed core 318 is accommodated in the solenoid housing 310, and the fixed core 318 extends from the valve housing 301 toward the end cap 312 to the center of the solenoid 316. The end cap 312 side of the fixed core 318 is surrounded by a sleeve 320, and the sleeve 320 has a closed end on the end cap 312 side.

The fixed core 318 has an insertion hole 318 a at the center, and one end of the insertion hole 318 a opens into the valve chamber 303. Further, a movable core accommodating space 324 for accommodating the cylindrical movable core 322 is defined between the fixed core 318 and the closed end of the sleeve 320, and the other end of the insertion hole 318a is opened to the movable core accommodating space 324. doing.
A solenoid rod 326 is slidably inserted into the insertion hole 318a, and a valve body 304 is integrally and coaxially connected to one end of the solenoid rod 326. The other end of the solenoid rod 326 projects into the movable core housing space 324, and the other end of the solenoid rod 326 is fitted into a through hole formed in the movable core 322 so that the solenoid rod 326 and the movable core 322 are integrated. Has been. An open spring 328 is disposed between the stepped surface of the movable core 322 and the end surface of the fixed core 318, and a predetermined gap is secured between the movable core 322 and the fixed core 318.

The movable core 322, the fixed core 318, the solenoid housing 310, and the end cap 312 are formed of a magnetic material and constitute a magnetic circuit. The sleeve 320 is made of a non-magnetic stainless steel material.
A pressure-sensitive port 310 a is formed in the solenoid housing 310, and a suction chamber 140 is connected to the pressure-sensitive port 310 a through a pressure-sensitive passage 166. A pressure-sensitive groove 318b extending in the axial direction is formed on the outer peripheral surface of the fixed core 318, and the pressure-sensitive port 310a and the pressure-sensitive groove 318b communicate with each other. Accordingly, the suction chamber 140 and the movable core housing space 324 communicate with each other through the pressure-sensitive port 310a and the pressure-sensitive groove 318b. , That is, the suction pressure Ps acts.

A control device 400B provided outside the compressor 100 is connected to the solenoid 316, and when a control current I is supplied from the control device 400B, the solenoid 316 generates an electromagnetic force G (I). The electromagnetic force G (I) of the solenoid 316 attracts the movable core 322 toward the fixed core 318 and acts on the valve body 304 in the valve closing direction.
In the capacity control valve 300, preferably, when the valve body 304 closes the valve hole 301a, the pressure in the discharge chamber 142, that is, the pressure receiving area of the valve body 304 on which the discharge pressure Pd acts (referred to as the seal area Sv). And the area of the valve body 304 on which the suction pressure Ps acts, that is, the cross-sectional area of the solenoid rod 326 is formed to be equal.

  In this case, the pressure of the crank chamber 105, that is, the crank pressure Pc substantially does not act on the valve body 304 in the opening / closing direction. Accordingly, the forces acting on the valve body 304 are the discharge pressure Pd, the suction pressure Ps, the electromagnetic force G (I) of the solenoid 316, and the biasing force fs5 of the release spring 328, and the discharge pressure Pd and the release spring 328 The biasing force fs5 acts in the valve opening direction, and the other suction pressure Ps and the electromagnetic force G (I) of the solenoid 316 act in the valve closing direction opposite to the valve opening direction.

  This relationship is expressed by equation (5), and equation (6) is obtained by transforming equation (5). From these equations (5) and (6), it is understood that the suction pressure Ps is determined if the discharge pressure Pd and the electromagnetic force G (I), that is, the control current I are determined.

  Based on such a relationship, as shown in FIG. 12, if the target suction pressure Pss is determined in advance as the target value of the suction pressure Ps and information on the changing discharge pressure Pd is known, the electromagnetic force G ( I) That is, the control current I can be calculated. When the control current I supplied to the solenoid 316 is adjusted to be equal to the calculated control current I, the valve body 304 operates so that the suction pressure Ps approaches the target suction pressure Pss, and the crank pressure Pc is reduced. Adjusted. That is, the discharge capacity is controlled so that the suction pressure Ps approaches the target suction pressure Pss.

  In the control that brings the suction pressure Ps closer to the target suction pressure Pss as described above, referring to FIG. 12, the set range of the target suction pressure Pss, that is, the control of the suction pressure Ps according to the level of the discharge pressure Pd. The range can be slid up and down. That is, the control range of the suction pressure Ps at the arbitrary discharge pressure Pd1 is slid to the higher side than the control range of the suction pressure Ps at the discharge pressure Pd2 lower than the discharge pressure Pd1.

Further, from the equation (6), it can be seen that if the seal area Sv is set small, the control range of the target suction pressure Pss at an arbitrary discharge pressure Pd can be expanded with a small electromagnetic force G (I). If the synergistic effect of the slide of the control range of the target suction pressure Pss and the expansion of the control range is exhibited, the control range of the target suction pressure Pss is greatly expanded.
In addition, if the energization amount to the solenoid 316 is increased, the suction pressure Ps can be decreased. On the other hand, if the energization amount to the solenoid 316 is zero, the valve body 304 is separated by the biasing force fs5 of the opening spring 328 and the valve hole 301a is forcibly opened. As a result, the refrigerant is introduced from the discharge chamber 142 into the crank chamber 105, and the discharge capacity is kept to a minimum.

FIG. 13 is a block diagram showing a schematic configuration of a capacity control system B including the control device 400B.
The capacity control system B is different from the capacity control system A in that it has a target suction pressure setting means 426 and a control signal calculation means 428 instead of the target suction pressure setting means 420. Therefore, hereinafter, the target suction pressure setting unit 426 and the control signal calculation unit 428 will be described.

The target suction pressure setting means 426 sets a deviation ΔT between the evaporator outlet air temperature Te actually detected by the evaporator temperature sensor 402 and the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401. Based on this, a target suction pressure Pss that is a target value of the suction pressure Ps that is a control target is set.
The target suction pressure setting means 420 of the capacity control system A also sets the control current I, but the target suction pressure setting means 426 of the capacity control system B only sets the target suction pressure Pss. Then, the set target suction pressure Pss is input to the control signal calculation means 428.

  The control signal setting means 428 generates a control current I to be supplied to the solenoid 316 based on the target suction pressure Pss set by the target suction pressure setting means 420 and the discharge pressure Pd detected by the discharge pressure detection means. Calculate. The calculated control current I may be limited within a predetermined upper and lower limit range. The control signal setting unit 428 generates a signal (discharge capacity control signal) corresponding to the calculated control current I or a duty ratio as a parameter related to the control current I, and inputs the signal to the control signal limiting unit 422. .

The operation (usage method) of the capacity control system B described above will be described below.
The main routine executed by the control device 400B is substantially the same as the main routine executed by the control device 400A. Referring to FIG. 9, the initial condition setting of the main routine S16 where the control unit 400B performs the control current I supplied to the solenoid 316, the displacement of the compressor 100 is set to an initial value I ₀ to the minimum capacity The

However, the suction pressure control routine S18 executed by the control device 400B is different from the suction pressure control routine S14 executed by the control device 400A. Therefore, in S16, the flag F1 is further set to zero and the timer is reset to zero. Further, in S16, the target suction pressure Pss is set to an initial value Pss _0. The initial value Pss ₀ is set, for example, by the following equation in accordance with the outside air temperature Ta.

Pss ₀ = K1 ・ Ta + K2 (K1 and K2 are constants)
FIG. 14 is a flowchart showing details of the suction pressure control routine S18 executed by the capacity control system B.
In the suction pressure control routine S18, the discharge pressure Pd detected by the discharge pressure detecting means is read (S150).

In the suction pressure control routine S18, it is determined whether or not the flag F1 is 0 (S152). Since the flag F1 is 0 under the initial condition, the determination result is Yes, the timer is started, the measurement of the elapsed time t is started (S154), and the flag F1 is set to 1 (S156).
Then, a target suction pressure Pss that is a control target is set in the target suction pressure setting routine S158. Thereafter, the control current I energized to the solenoid 316 is calculated from the target suction pressure Pss set in S158 and the discharge pressure Pd detected by the discharge pressure detecting means by a predetermined calculation formula (S160). For example, as shown in FIG. 14, the control current I is calculated as a value obtained by multiplying the difference between the discharge pressure Pd and the target suction pressure Pss by the proportional constant b1 and adding the constant b2.

It is compared and determined whether or not the control current I calculated in S160 is equal to or greater than a preset lower limit I3 (S162). As a result of the determination in S162, when the calculated control current I is smaller than the lower limit value I3 (in the case of No), the lower limit value I3 is read as the control current I (S164).
On the other hand, as a result of the determination in S162, if the calculated control current I is equal to or greater than the lower limit value I3 (in the case of Yes), the calculated control current I is equal to or less than the upper limit value I4 that is greater than the preset lower limit value I3. Whether or not there is a comparison is determined (S166). As a result of the determination in S166, if the control current I exceeds the upper limit value I4 (in the case of No), the upper limit value I4 is read as the control current I (S168).

Hereinafter, setting of the threshold (S170), calculation of the estimated suction pressure Pse (S172), setting of the index (S174), comparison determination between the threshold and the index (S176), the control current I at the control current Ii corresponding to the index The replacement (S180) and the output of the control current I (S178) are substantially the same as those in S112 to S126 in the main routine of the capacity control system A.
However, in the setting of the threshold value in S170, the threshold value is set based on the target suction pressure Pss set in S158, and in this embodiment, for example, the lower limit value PssL of the variation range of the target suction pressure Pss is set as the threshold value. .

In S180, when the control current I is replaced with the control current Ii corresponding to the index, as in S160, the following formula:
Ii = b1 ・ (Pd-PseH) + b2 (b1, b2 constant)
Based on the control current Ii is calculated. Then, the control current I is replaced with the calculated control current Ii.

After S178, the program returns from the suction pressure control routine S18 to the main routine, and if the determination result in S12 is Yes, the second suction pressure control routine S18 is executed.
In the second suction pressure control routine S18, since the flag F1 was set to 1 in the previous S156, the determination result in S152 is No, and it is determined whether the elapsed time t measured by the timer has reached the predetermined time t1. (S182). As a result of the determination in S182, if the predetermined time t1 has not elapsed since the start of the timer (in the case of Yes), the control current I is calculated from the target suction pressure Pss set in the previous S158 and the discharge pressure Pd read in the current S150. Is calculated (S160). Thereafter, the control device 400B returns to the main routine via S178 as in the first time.

On the other hand, when the elapsed time t of the timer exceeds the predetermined time t1, the determination result in S182 is No, the timer is reset (S184), and the flag F1 is set to 0 (S186). That is, the target suction pressure Pss is updated every predetermined time t1. The predetermined time t1 as the update time is set to 5 seconds, for example.
That is, in the control device 400B, the control current I is calculated so that the suction pressure Ps maintains the target suction pressure Pss based on the discharge pressure Pd that is constantly read and the target suction pressure Pss that is updated every predetermined time t1. Is done. If the threshold value is smaller than the index, the solenoid 316 has not the control current I calculated based on the discharge pressure Pd and the target suction pressure Pss but the control current Ii calculated based on the discharge pressure Pd and the index. Supplied.

FIG. 15 is a flowchart showing details of the target suction pressure setting routine S158 in FIG.
The setting reading of the evaporator target outlet air temperature Tes (S200), the reading of the evaporator outlet air temperature (S202), and the calculation of the deviation ΔT (S204) in the target suction pressure setting routine S158 are the suction pressure control of the capacity control system A. This is the same as S100, S102, and S104 in routine S14.

Then, based on the calculated deviation ΔT, for example, the target suction pressure Pss is calculated by a predetermined calculation formula for PI control (S206).
Incidentally, in the equation of S206, but contains the target suction pressure Pss, the initial value of the target suction pressure Pss is Pss _0.
Each time the target suction pressure setting routine S158 is executed once, the deviation ΔT is calculated in S204, and the subscript n of the deviation ΔT in the calculation formula of S206 is obtained by calculating the deviation ΔT in the current S204. It shows that. Similarly, the subscript n-1 indicates that the deviation ΔT has been calculated in the previous S204.

Thereafter, it is compared and determined whether or not the calculated target suction pressure Pss is equal to or higher than a preset lower limit value Ps1 (S208). If the result of the determination in S208 is No, the lower limit value Ps1 is read as the target suction pressure Pss (S210).
On the other hand, if the determination result in S208 is Yes, it is determined whether or not the calculated Pss is equal to or less than the upper limit value Ps2 that is greater than the preset Ps1 (S212). If the determination result in S212 is No, the upper limit value Ps2 is read as the target suction pressure Pss (S214).

Therefore, if Ps1 ≦ Pss ≦ Ps2 as a result of the determination in S208 and S212, the target suction pressure Pss calculated in S203 is set as the target suction pressure Pss as it is.
Also in the capacity control system B described above, when the threshold value is smaller than the index, the power consumption of the capacity control valve 300 is reduced by reducing the control current I supplied to the solenoid 316 to the control current Ii corresponding to the index. Is done.

In the capacity control system B, the capacity control valve 300 has a simple structure that does not include the pressure sensor 228 for mechanically feedback controlling the suction pressure Ps. For this reason, it is easy to secure a mounting space for the capacity control valve 300 in the compressor 100 and the degree of freedom of the mounting posture is increased.
On the other hand, in this capacity control system B, even if the capacity control valve 300 without the pressure sensor 228 is used, the target suction pressure setting means 426 sets the target suction pressure Pss and is based on the target suction pressure Pss and the discharge pressure Pd. By calculating the control current I, the discharge capacity is controlled so that the suction pressure Ps approaches the target suction pressure Pss.

  Furthermore, in this capacity control system B, the suction pressure Ps and the electromagnetic force G (I) of the solenoid 316 act against the discharge pressure Pd acting on the valve body 304, so that the control range of the suction pressure Ps. Is wide. As a result, according to the air conditioning system provided with the capacity control system B, the power consumption of the capacity control valve 300 becomes effective immediately after the air conditioner switch is turned on, in other words, immediately after the compressor 100 is started. Reduced.

  On the other hand, the compressor 100 is a reciprocating type and can set the stroke of the piston 130 defined by the minimum inclination angle of the swash plate 107 to be very small. For this reason, the minimum discharge capacity is very small, and the mechanical variable range of the discharge capacity is wide. Therefore, when the capacity control system B is applied to the compressor 100, the effect of expanding the control range of the suction pressure Ps by setting the target suction pressure Pss is sufficiently exhibited, the variable range of the discharge capacity is wide, and the power consumption Therefore, it is possible to provide an air conditioning system with reduced power consumption.

The present invention is not limited to the first and second embodiments described above, and various modifications are possible.
In the capacity control systems A and B of the first and second embodiments, the pressure sensor 403 detects the pressure of the refrigerant in the discharge pressure region, but the position where the pressure sensor 403 is disposed is not particularly limited, and the refrigeration cycle 10 You may arrange | position in any site | part of a high voltage | pressure area | region. That is, the estimated suction pressure Pse and the superheat degree SH may be calculated based on the pressure of the refrigerant in the high pressure region. The high pressure region is a region obtained by adding a region from the radiator 14 to the inlet of the expander 16 to the discharge pressure region.

  In the capacity control systems A and B of the first and second embodiments, when the threshold value is lower than the index in the determination result of S122, the control current Ii is output as the control current I, but is supplied to the solenoids 254 and 316. Even if the control current I is not reduced to be equal to the control current Ii, it may be made smaller than the control current I required to reach the target suction pressure Pss. This is because the power consumption of the capacity control valves 200 and 300 is reduced by the amount by which the control current I is reduced.

However, in order to further reduce the power consumption, the control current I supplied to the solenoids 254 and 316 is reduced until it becomes equal to the control current Ii, or the control current I supplied to the solenoids 254 and 316 is reduced. It is preferable to make it smaller than the control current Ii.
In addition, when the control current I supplied to the solenoids 254 and 316 is reduced to be equal to the control current Ii, the compressor 100 controls the index in the region where the operation is performed at the maximum discharge capacity. Therefore, the power consumption of the compressor 100 is reduced and the reliability is ensured.

  In particular, when the rotational speed Ncn of the compressor 100 is equal to or greater than a predetermined value, the suction pressure Ps reaches the target suction pressure Pss if the control current I supplied to the solenoids 254 and 316 is made smaller than the control current Ii. The power consumption in the compressor 100 is reduced by making the discharge capacity of the compressor 100 smaller than the maximum discharge capacity without increasing the time to do so. This is due to the following reason.

Depending on the operating conditions of the vehicle or the air conditioning system, there is a case where it is not necessary to operate the compressor 100 at the maximum discharge capacity immediately after the compressor 100 is started even if the suction pressure Ps is brought close to the target suction pressure Pss.
For example, when the vehicle is traveling at a high speed, the rotational speed Ncn of the compressor 100 becomes very high, and the capacity of the compressor 100 also increases. However, the capacity of the air conditioning system is limited by the overall configuration of the air conditioning system, and in particular by the capacity of the evaporator 18. Therefore, even if the capacity of the compressor 100 increases, the capacity of the compressor 100 cannot be fully utilized. Therefore, in such a case, when the compressor 100 operates at the maximum discharge capacity, power is wasted in the compressor 100.

Therefore, if the control current I supplied to the solenoids 254 and 316 is smaller than the control current Ii when the rotational speed Ncn of the compressor 100 is equal to or greater than a predetermined value, the compressor 100 is matched to the capacity of the evaporator 18. The power consumption of the compressor 100 can be saved.
In particular, when the rotational speed Ncn of the compressor 100 is equal to or greater than a predetermined value and the thermal load Q of the evaporator 18 is equal to or greater than a predetermined value, the control current I supplied to the solenoids 254 and 316 is set to be greater than the control current Ii. If it is made smaller, not only the effect of reducing the power consumption in the compressor 100 is great, but also the mechanical load on the compressor 100 is reduced. As a result, the reliability of the compressor 100 is also ensured.

In the capacity control systems A and B of the first and second embodiments, the lower limit value PssL of the variation range of the target suction pressure Pss is set as the threshold value. However, the threshold value is set based on the target suction pressure Pss. Just do it. Therefore, the target suction pressure Pss itself or the upper limit value PssH of the variation range of the target suction pressure Pss may be set as the threshold value.
Moreover, although the upper limit value PseH of the variation range of the estimated suction pressure Pse is set as an index, the index only needs to be set based on the estimated suction pressure Pse. Therefore, the estimated suction pressure Pse itself or the lower limit value PseL of the variation range of the estimated suction pressure Pse may be set as an index.

  Then, as the threshold value, one selected from the target suction pressure Pss, the lower limit value PssL and the upper limit value PssH of the variation range can be used, and the estimated suction pressure Pse, the lower limit value PseL and the upper limit of the variation range can be used as indices. Since one selected from the value PseH can be used, there are nine combinations of thresholds and indices. From these combinations, a combination of a threshold and an index can be selected as appropriate.

As in the capacity control systems A and B of the first and second embodiments, the lower limit value PssL of the variation range of the target suction pressure Pss is set as a threshold value, and the upper limit value PseH of the variation range of the estimated suction pressure Pse is used as an index. Is reliably prevented from being supplied to the solenoids 254 and 316 in excess of the maximum capacity energization amount. This is due to the following reason.
Since the lower limit value PssL is the lower limit value of the range of variation in the target suction pressure Pss generated due to the component size tolerance during production of the capacity control valves 200 and 300, the lower limit value PssL corresponds to the target suction pressure Pss. The suction pressure Ps is the minimum value that can be reached when the control current I is supplied to the solenoids 254 and 316.

On the other hand, since the upper limit value PseH is the upper limit value of the variation range of the estimated suction pressure Pse generated by the estimation accuracy of the estimated suction pressure Pse, the upper limit value PseH is the actual value when the estimated suction pressure Pse is estimated. Is the maximum value that can be taken.
Therefore, if the lower limit value PssL as the threshold is lower than the upper limit value PseH as an index (PssL <PseH), the suction pressure Ps reaches when the control current I corresponding to the target suction pressure Pss is supplied to the solenoids 254 and 316. The possible pressure may be lower than the actual suction pressure Ps at the estimated time. Therefore, when PssL <PseH, the compressor 100 may be operating at the maximum discharge capacity. If the compressor 100 is operating at the maximum discharge capacity, the compressor 100 is supplied to the solenoids 254 and 316. By making the control current I smaller than the control current I corresponding to the target suction pressure Pss, the excessive control current I can be reduced.

Therefore, if the control current I is reduced when PssL <PseH, the control current I exceeding the maximum capacity energization amount is supplied to the solenoids 254 and 316 even if the target suction pressure Pss and the estimated suction pressure Pse vary. Is reliably prevented.
In the capacity control systems A and B of the first and second embodiments, the upper limit value PssH or the lower limit value PssL of the variation range of the target suction pressure Pss can be set as the threshold value. The difference is preferably changed according to the target suction pressure Pss. Specifically, it is preferable that the difference between the target suction pressure Pss and the threshold value increases as the target suction pressure Pss increases. In the capacity control systems A and B, when the threshold value is lower than the index, it is substantially determined that the compressor 100 is operating at the maximum discharge capacity, and the difference between the target suction pressure Pss and the threshold value is the target value. This is because the determination accuracy is improved by changing according to the magnitude of the suction pressure Pss. As a result, when the compressor 100 is operating at the maximum discharge capacity, the excessive control current I supplied to the solenoids 254 and 316 is more reliably reduced, and the power consumption in the capacity control valves 200 and 300 is reduced. Reduced.

  In the capacity control systems A and B of the first and second embodiments, the configuration of the thermal load detection means for detecting the thermal load Q of the evaporator 18 is not particularly limited. The thermal load detection means includes an outside air temperature Ta, an outside air humidity, a solar radiation amount, an air flow rate of the evaporator fan, an evaporator fan voltage Vf related to the air flow rate, an inside / outside air switching door position, a vehicle interior temperature setting, an outlet position, Air mix door position, vehicle interior temperature Tt, vehicle interior humidity, air temperature and humidity at the inlet of the evaporator 18 in the air circuit, surface temperature of each part of the vehicle interior, refrigerant temperature in the high pressure region and low pressure region of the refrigeration cycle 10 The thermal load Q can be detected by using one or more selected from the group consisting of the number of passengers of the vehicle and the like. However, in order to accurately detect the thermal load Q, it is preferable that the thermal load detection means includes at least an outside air temperature sensor 404 and an evaporator fan voltage detection means 406.

In the capacity control systems A and B of the first and second embodiments, when the discharge capacity control signal corresponds to the duty ratio for adjusting the control current I, the solenoid driving means 424 has the current sensor 436. You don't have to.
In this case, in the capacity control system A, a correlation between the target suction pressure Pss and the duty ratio for driving the switching element 430 may be obtained in advance. When the deviation ΔT between the evaporator target outlet air temperature Tes set by the evaporator target temperature setting means 401 and the evaporator outlet air temperature Te detected by the evaporator temperature sensor 402 is determined, the duty ratio is determined based on the correlation. Can be calculated.

In the capacity control system B, if the correlation between the control current I and the duty ratio is obtained in advance, the duty ratio can be directly calculated based on the correlation in S160 and S180.
In the capacity control system B of the second embodiment, in S160 and S180 of the suction pressure control routine S18, I = α · Pd−β · Pss + γ (where α, β, and γ are constants) is used as an arithmetic expression for the control current I. The term (Pd−Pss) ⁿ may be included in the arithmetic expression to make it non-linear.

In the capacity control systems A and B of the first and second embodiments, the target suction pressure Pss is set based on the set evaporator target outlet air temperature Tes and external information without using the evaporator temperature sensor 402. May be.
As the external information used for setting the target suction pressure Pss, the same external information used for detecting the thermal load Q of the evaporator 18 can be used, and further, the operating state of the compressor 100 and the vehicle. Information about can be used. The information regarding the driving state of the vehicle is, for example, the rotational speed of the engine 114, the vehicle speed, the acceleration, and the like.

In the capacity control system A of the first embodiment, the discharge pressure Pd and the crank pressure Pc are not acting on the valve body 210 of the capacity control valve 200 in the opening and closing direction. A displacement control valve that acts on the valve body in the valve opening direction or the valve closing direction may be used.
In the capacity control system B of the second embodiment, the discharge pressure Pd and the suction pressure Ps act against the valve body 304 of the capacity control valve 300 so that the discharge pressure Pd and the suction pressure Ps are opposed to each other. Further, the crank pressure Pc may act when the two are opposed to each other.

In the capacity control system B of the second embodiment, a pressure sensor that mechanically feedback-controls the suction pressure Ps is not necessary for the capacity control valve 300. However, a bellows or a diaphragm may be used to cause the discharge pressure Pd, the suction pressure Ps, or the electromagnetic force G (I) to act on the valve body 304.
For example, when a small bellows having one end opened and the other end closed is used, the closed end of the bellows is fixed to one end of the valve body 304 opposite to the valve hole 301a. The portion of the solenoid rod 326 on the tip side is inserted into the bellows through the opening end of the bellows, and connects the tip of the solenoid rod 325 to the inner surface of the closed end of the bellows. As a result, the solenoid rod 326 enables the valve body 304 to be biased by the electromagnetic force G (I). The pressure inside the bellows is made equal to the suction pressure Ps, and the suction pressure Ps is applied to the valve body 304.

  The compressor 100 to which the capacity control systems A and B of the first and second embodiments are applied is a clutchless compressor, but the capacity control systems A and B are also applied to a compressor equipped with an electromagnetic clutch. Is possible. Although the compressor 100 is a swash plate type reciprocating compressor, it may be a rocking plate type reciprocating compressor. The oscillating plate compressor has an element for oscillating the oscillating plate. The swash plate 107 and these elements are collectively referred to as a swash plate element. The compressor 100 may be driven by an electric motor.

Further, the capacity control systems A and B can be applied to a scroll type or vane type variable capacity compressor. In other words, if the control pressure for changing the discharge capacity can be changed by the valve opening of the capacity control valve using the capacity control valve in which the electromagnetic force of the solenoid acts on the valve body, it can be applied to any variable capacity compressor. Is possible.
The control pressure is the crank chamber pressure (crank pressure Pc) in the case of a reciprocating compressor.

In the compressor 100 to which the capacity control systems A and B of the first and second embodiments are applied, in order to increase the crank pressure Pc by regulating the flow rate of the extraction passage 162, a fixed orifice as a throttle element is provided in the extraction passage 162. Although 103c is arranged, a throttle with variable flow rate may be used as the throttle element, or a valve may be arranged to adjust the valve opening.
In the capacity control systems A and B of the first and second embodiments, the capacity control valves 200 and 300 are disposed in the air supply passage 160 that connects the discharge chamber 142 and the crank chamber 105. In the case of the swash plate type or the oscillating plate type, the capacity control valve 300 may be disposed in the extraction passage 162 connecting the crank chamber 105 and the suction chamber 140 without disposing the capacity control valve 300 in the air supply passage 160. . That is, the present invention is not limited to the inlet control that controls the opening degree of the air supply passage 160, and may be the outlet control that controls the opening degree of the extraction passage 162.

  According to the capacity control valves 200 and 300 used in the capacity control systems A and B of the first and second embodiments, the suction pressure Ps decreases as the control current I decreases, but the suction pressure increases as the control current I increases. You may use the capacity | capacitance control valve which operate | moves so that Ps may fall. In this case, when the target suction pressure Pss or the threshold value is lower than the estimated suction pressure Pse or the index, the control current I or a parameter related to the control current I is increased so that the discharge capacity becomes equal to or less than the maximum discharge capacity. Therefore, when such a capacity control valve is used, even if the control current I or a parameter related to the control current I is adjusted based on the target suction pressure Pss and the estimated suction pressure Pse, the power consumption of the capacity control valve However, the reliability of the compressor 100 is ensured by making the discharge capacity equal to or less than the maximum discharge capacity.

In the capacity control systems A and B of the first and second embodiments, the temperature automatic expansion valve is used as the expander 16, but the expander 16 is not limited to this and may be an orifice or an electronic expansion valve.
In the refrigeration cycle 10 to which the capacity control systems A and B of the first and second embodiments are applied, the refrigerant is not limited to R134a or carbon dioxide, and other new refrigerants may be used. That is, the capacity control systems A and B can be applied to a conventional air conditioning system.

  Finally, the capacity control system of the variable capacity compressor according to the present invention is applicable to air conditioning systems in general, such as indoor air conditioning systems other than vehicle air conditioning systems.

It is a figure which shows schematic structure of the refrigerating cycle of the vehicle air-conditioning system to which the capacity | capacitance control system of 1st Embodiment is applied with the longitudinal cross-section of a variable capacity compressor. It is a longitudinal cross-sectional view which shows schematic structure of the expander used for the refrigerating cycle of FIG. It is a graph for showing the superheat characteristic in the refrigeration cycle of FIG. 1, C1 shows the relationship between the temperature and pressure of the refrigerant at the outlet of the evaporator when the pressure of the refrigerant at the inlet of the expander is constant, C2 indicates the relationship between the saturation temperature and saturation pressure of the expander filler. It is a graph which shows the relationship between the superheat degree of the refrigerant | coolant in the exit of an evaporator, and the pressure of the refrigerant | coolant in the inlet of an expander in the refrigerating cycle of FIG. It is a figure for demonstrating schematic structure of the capacity | capacitance control valve used for the refrigerating cycle of FIG. 1 with the connection state of the capacity | capacitance control valve in a compressor. FIG. 2 is a graph showing a relationship between a control current of a capacity control valve and a target suction pressure, a threshold value, and an index in the refrigeration cycle of FIG. 1. It is a block diagram which shows schematic structure of the capacity | capacitance control system of 1st Embodiment. It is a block diagram for demonstrating schematic structure of the solenoid drive means in the capacity | capacitance control system of FIG. It is a control flowchart which shows the main routine which the capacity | capacitance control system of FIG. 10 is a control flowchart of a suction pressure control routine included in the main routine of FIG. It is a figure for demonstrating schematic structure of the capacity control valve used for the capacity control system of 2nd Embodiment with the connection state of the capacity control valve in a compressor. 12 is a graph showing a relationship among a control current, a target suction pressure, and a discharge pressure in the capacity control valve of FIG. It is a block diagram which shows schematic structure of the capacity | capacitance control system of 2nd Embodiment. 14 is a control flowchart of a suction pressure control routine included in a main routine executed by the capacity control system of FIG. 13. 15 is a control flowchart of a target suction pressure setting routine included in the suction pressure control routine of FIG.

Explanation of symbols

254 Solenoid 401 Evaporator target temperature setting means (external information detection means)
402 Evaporator temperature sensor (external information detection means)
403 Pressure sensor (external information detection means)
404 Outside air temperature sensor (external information detection means)
405 In-vehicle temperature sensor (external information detection means)
406 Evaporator fan voltage detection means (external information detection means)
407 Inside / outside air switching door position detecting means (external information detecting means)
408 Engine speed sensor (external information detection means)
414 Suction pressure estimating means 420 Target suction pressure setting means 422 Control signal limiting means (control current adjusting means)
424 Solenoid driving means (control current adjusting means)

Claims (15)

Applied to variable capacity compressors inserted together with radiators, expanders and evaporators in the circulation path where refrigerant circulates to form the refrigeration cycle of the air conditioning system, and adjust the control pressure to bring the suction pressure closer to the target suction pressure In the capacity control system to
External information detection means for detecting one or more external information;
Target suction pressure setting means for setting the target suction pressure based on external information detected by the external information detection means;
A displacement control valve having a solenoid for adjusting the control pressure;
Suction pressure estimating means for calculating an estimated suction pressure that is an estimated value of the suction pressure when it is assumed that the discharge capacity of the variable capacity compressor is maximum based on the external information detected by the external information detecting means. When,
Based on the target suction pressure set by the target suction pressure setting means and the estimated suction pressure calculated by the suction pressure estimation means, a control current supplied to the solenoid of the capacity control valve or a parameter related to the control current and a control current adjusting means for adjusting,
The control current adjusting means is
When the target suction pressure is lower than the estimated suction pressure, a control current supplied to the solenoid is compared with a control current necessary for causing the suction pressure to reach the target suction pressure or a parameter related to the control current. Alternatively, a capacity control system for a variable capacity compressor, wherein a parameter related to the control current is reduced . Applied to variable capacity compressors inserted together with radiators, expanders and evaporators in the circulation path where refrigerant circulates to form the refrigeration cycle of the air conditioning system, and adjust the control pressure to bring the suction pressure closer to the target suction pressure In the capacity control system to
External information detection means for detecting one or more external information;
Target suction pressure setting means for setting the target suction pressure based on external information detected by the external information detection means;
A displacement control valve having a solenoid for adjusting the control pressure;
Suction pressure estimating means for calculating an estimated suction pressure that is an estimated value of the suction pressure when it is assumed that the discharge capacity of the variable capacity compressor is maximum based on the external information detected by the external information detecting means. When,
Based on the target suction pressure set by the target suction pressure setting means and the estimated suction pressure calculated by the suction pressure estimation means, a control current supplied to the solenoid of the capacity control valve or a parameter related to the control current And a control current adjusting means for adjusting
The control current adjusting means is
Including a threshold setting means for setting a threshold based on the target suction pressure;
When the threshold value is lower than the estimated suction pressure, the control current or the control current supplied to the solenoid is compared with the control current necessary for the suction pressure to reach the threshold value or a parameter related to the control current. variable displacement compressor capacity control system you wherein reducing the parameters related to. Applied to variable capacity compressors inserted together with radiators, expanders and evaporators in the circulation path where refrigerant circulates to form the refrigeration cycle of the air conditioning system, and adjust the control pressure to bring the suction pressure closer to the target suction pressure In the capacity control system to
External information detection means for detecting one or more external information;
Target suction pressure setting means for setting the target suction pressure based on external information detected by the external information detection means;
A displacement control valve having a solenoid for adjusting the control pressure;
Suction pressure estimating means for calculating an estimated suction pressure that is an estimated value of the suction pressure when it is assumed that the discharge capacity of the variable capacity compressor is maximum based on the external information detected by the external information detecting means. When,
Based on the target suction pressure set by the target suction pressure setting means and the estimated suction pressure calculated by the suction pressure estimation means, a control current supplied to the solenoid of the capacity control valve or a parameter related to the control current And a control current adjusting means for adjusting
The control current adjusting means is
Threshold setting means for setting a threshold based on the target suction pressure;
Index setting means for setting an index based on the estimated suction pressure,
When the threshold value is lower than the index, the control current supplied to the solenoid or the control current is related to the control current required for the suction pressure to reach the threshold or the parameter related to the control current. variable displacement compressor capacity control system characterized in that to reduce the parameters to be. The threshold is one of an upper limit value and a lower limit value of the variation range of the target suction pressure,
4. The capacity control system for a variable capacity compressor according to claim 3 , wherein a difference between the target suction pressure and the threshold value changes in accordance with a magnitude of the target suction pressure. The threshold is the lower limit of the variation range of the target suction pressure, the indicator is a variable displacement compressor according to claim 3 or 4, characterized in that the upper limit of the variation range of the estimated suction pressure Capacity control system. When the target suction pressure or the threshold value is lower than the estimated suction pressure or the threshold value, the control current adjusting means is configured to control the control current necessary for the suction pressure to reach the estimated suction pressure or the index so that the following parameters associated with the control current, the variable displacement compressor according to any one of claims 1 to 5, characterized in that to reduce the parameters related to the control current or the control current supplied to the solenoid Capacity control system. The external information detection means has a rotation speed detection means for detecting a physical quantity related to the rotation speed of the variable capacity compressor,
The control current adjusting means is a control current supplied to the solenoid so that a discharge capacity of the variable capacity compressor becomes smaller than a maximum when a physical quantity detected by the rotation speed detecting means is a predetermined value or more. 7. The capacity control system for a variable capacity compressor according to claim 6 , wherein a parameter related to the control current is limited. The external information detection means has a heat load detection means for detecting a heat load of the evaporator,
The control current adjusting means is arranged so that when the heat load of the evaporator detected by the heat load detecting means is equal to or greater than a predetermined value, the discharge capacity of the variable capacity compressor is made smaller than the maximum. 8. The capacity control system for a variable capacity compressor according to claim 7 , wherein a control current to be supplied or a parameter related to the control current is limited. The suction pressure estimation means calculates the estimated suction pressure by substituting the external information detected by the external information detection means into an empirical formula indicating the relationship between the external information and the estimated suction pressure. displacement control system for a variable capacity compressor according to any one of claims 1 to 8, characterized. The external information detecting means is
A discharge pressure detecting means for detecting a discharge pressure which is a pressure of the refrigerant in any part of a discharge pressure region of the refrigeration cycle;
Thermal load detection means for detecting the thermal load of the evaporator;
Superheat degree detection means for detecting the superheat degree of the refrigerant at the outlet of the evaporator;
A rotational speed detection means for detecting a physical quantity corresponding to the rotational speed of the variable capacity compressor,
The suction pressure estimating means includes the discharge pressure detected by the discharge pressure detecting means, the heat load of the evaporator detected by the thermal load detecting means, and the refrigerant detected by the superheat degree detecting means. The estimated suction pressure is calculated using an empirical formula indicating a relationship between a superheat degree, a physical quantity related to the rotational speed of the variable capacity compressor detected by the rotational speed detection means, and the suction pressure. The capacity control system for a variable capacity compressor according to claim 9 . The expander is a temperature automatic expansion valve that adjusts the flow rate of the refrigerant based on the temperature of the refrigerant at the outlet of the evaporator;
The superheat degree detecting means includes means for detecting the temperature of the refrigerant at the outlet of the evaporator or a physical quantity related to the temperature, and an expander inlet for detecting the pressure of the refrigerant at the inlet of the expander. Pressure sensing means,
The superheat degree detection means detects the superheat degree based on the temperature of the refrigerant at the outlet of the evaporator or a physical quantity related to the temperature and the pressure of the refrigerant at the inlet of the expander. The capacity control system for a variable capacity compressor according to claim 10 , wherein the capacity control system is a variable capacity compressor. The air conditioning system is applied to a vehicle,
The thermal load detecting means is
An outside temperature sensor for detecting the outside temperature;
The capacity control system for a variable capacity compressor according to claim 10 , further comprising at least an evaporator fan voltage detecting means for detecting a voltage applied to a fan for the evaporator. The external information detection means includes an evaporator target outlet temperature setting means for setting an evaporator target outlet air temperature that is a target of the temperature of the air flow immediately after passing through the evaporator,
The target suction pressure estimating means sets the target suction pressure so that the temperature of the air flow immediately after passing through the evaporator approaches the evaporator target outlet air temperature set by the evaporator target outlet temperature setting means. The capacity control system of a variable capacity compressor according to any one of claims 1 to 12 . The capacity control valve receives the discharge pressure when the pressure of the refrigerant in any part of the discharge pressure region of the refrigeration cycle is a discharge pressure, and the suction pressure in a direction opposite to the discharge pressure. And a valve body capable of opening and closing a valve hole in response to one of the control pressures and the electromagnetic force of the solenoid, and changing the control pressure by opening and closing the valve hole to change the capacity of the variable capacity compressor Is adjustable,
The external information detection means includes discharge pressure detection means for detecting the discharge pressure,
The control current adjusting means is configured to obtain a control current necessary for the suction pressure to reach the target suction pressure or the control current based on the discharge pressure detected by the discharge pressure detection means and the target suction pressure. The related parameter is calculated, The capacity control system of the variable capacity compressor according to any one of claims 1 to 13 . The variable capacity compressor is:
A housing in which a discharge chamber, a crank chamber, a suction chamber and a cylinder bore are defined;
A piston disposed in the cylinder bore;
A drive shaft rotatably supported in the housing;
A conversion mechanism including a variable swash plate element that converts rotation of the drive shaft into reciprocating motion of the piston;
An air supply passage communicating the discharge chamber and the crank chamber;
A bleed passage for communicating the suction chamber and the crank chamber;
Said displacement control valve, the air supply passage and a displacement control system for a variable capacity compressor according to any one of claims 1 to 14, characterized in that it is inserted in one of the bleed passage.

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