WO2016035729A1

WO2016035729A1 - Discharge capacity control system for variable capacity compressor

Info

Publication number: WO2016035729A1
Application number: PCT/JP2015/074590
Authority: WO
Inventors: 田口　幸彦
Original assignee: サンデンホールディングス株式会社
Priority date: 2014-09-01
Filing date: 2015-08-31
Publication date: 2016-03-10
Also published as: JP2016050543A

Abstract

[Problem] To provide a discharge capacity control system for a variable capacity compressor with which it is possible, using a simple configuration and without including a displacement means, to avoid operation at a high discharge capacity while there is a shortage of coolant. [Solution] A discharge capacity control system 400 for a variable capacity compressor, the discharge capacity control system 400 controlling the discharge capacity of a variable capacity compressor 100 in which a radiator, an expander, and an evaporator are interposed in a coolant circulation path for circulating a coolant to constitute the refrigeration cycle of an air-conditioner system, and in which the discharge capacity varies on the basis of variation in the pressure in a control pressure chamber 140, wherein the discharge capacity control system 400 is provided with: a control valve 300 having a pressure-sensing member 306 that becomes displaced in the opening/closing direction of a valve body 305 in response to a differential pressure between two points on the coolant circulation path in the variable capacity compressor, and an actuator 310 for applying an urging force in the valve-closing direction to the valve body 305 in accordance with a supplied control current, the valve body 305 being displaced in accordance with the differential pressure between the two points and the urging force from the actuator 310, and the control valve 300 adjusting the opening degree of a pressure supply channel 145, which communicates between a discharge chamber 142 and the control pressure chamber 140, and varying the pressure within the control pressure chamber 140; a pressure detection means 403 for detecting the pressure in the low-pressure region of the coolant circulation path; and a control current supply means 410 for setting a control current and supplying the control current to the actuator 310 so as to reduce the discharge capacity when the pressure in the low-pressure region of the coolant circulation path falls below a lower limit value set in advance.

Description

Discharge capacity control system for variable capacity compressor

The present invention relates to a discharge capacity control system for a variable capacity compressor that is inserted in a refrigerant circuit to form a refrigeration cycle, and more particularly to a discharge capacity control system for a variable capacity compressor used in a vehicle air conditioner system or the like.

In Patent Document 1, a control valve that controls the discharge capacity of a variable capacity compressor with a differential pressure between two points in a discharge pressure area is used to control the valve of the control valve when the pressure in the suction pressure area falls below a preset reference pressure. A technique is disclosed in which a displacement means for increasing the opening is added to avoid operation with a large discharge capacity in a refrigerant shortage state.

JP 2006-177300 A

However, in the above technique, a displacement means is added to the control valve in order to avoid operation with a large discharge capacity in a refrigerant shortage state, which increases the cost of the control valve and increases the size of the control valve. There is a problem that the layout of the control valve in the variable capacity compressor becomes difficult.

Therefore, an object of the present invention is to provide a discharge capacity control system of a variable capacity compressor that can avoid operation with a large discharge capacity in a refrigerant shortage state with a simple configuration without having the displacement means.

The discharge capacity control system of the variable capacity compressor according to the present invention is inserted together with a radiator, an expander and an evaporator in a refrigerant circulation path through which refrigerant circulates to constitute a refrigeration cycle of an air conditioner system, and controls the pressure of the control pressure chamber. A system for controlling a discharge capacity of a variable capacity compressor whose discharge capacity changes based on a change, wherein the valve body opens and closes in response to a differential pressure between two points of a refrigerant circulation path inside the variable capacity compressor. A pressure-sensitive member that displaces the actuator, and an actuator that applies an urging force in the valve closing direction to the valve body in accordance with the supplied control current. The differential pressure between the two points and the urging force of the actuator The valve body is displaced in response, the control valve for changing the pressure in the control pressure chamber by adjusting the opening of the pressure supply passage communicating the discharge chamber and the control pressure chamber, and the low pressure region of the refrigerant circulation path In A pressure detecting means for detecting pressure, and a control for setting the control current so as to decrease the discharge capacity when the pressure in the low pressure region of the refrigerant circuit is lower than a preset lower limit value, and supplying the control current to the actuator Current supply means.

According to the discharge capacity control system, when the refrigerant is insufficient and the pressure in the low pressure region of the refrigerant circuit falls below a preset lower limit value, the control current supplied to the actuator is changed to reduce the discharge capacity. Therefore, it is possible to avoid operation with a large discharge capacity in a refrigerant shortage state. Since the control valve has a simple configuration having a pressure-sensitive member and an actuator, the cost of the control valve can be suppressed, and the layout of the control valve is facilitated.

It is sectional drawing of the variable capacity compressor and control valve to which this invention was applied. It is sectional drawing of the said control valve. It is a figure which shows the characteristic of the said control valve. It is the block diagram which showed the structure of the discharge capacity | capacitance control system which concerns on this invention. It is a figure which shows the relationship between the lower limit of the target value of the pressure of a suction pressure area | region, and the rotation speed of a variable capacity compressor. It is a figure which shows the control flow of the discharge capacity | capacitance control system which concerns on this invention. It is a figure which shows the control current characteristic in starting control of the said control flow. It is a figure which shows the air-conditioning control flow in the said control flow.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a variable capacity compressor 100 and a control valve 300 which are an example to which the present invention is applied.
This variable capacity compressor 100 is inserted together with a radiator, an expander, and an evaporator in a refrigerant circulation path through which refrigerant circulates to constitute a refrigeration cycle of a vehicle air conditioner system.

As shown in FIG. 1, a variable capacity compressor 100 includes a cylinder block 101 having a plurality of cylinder bores 101a, a front housing 102 provided at one end of the cylinder block 101, and a valve plate at the other end of the cylinder block 101. And a cylinder head 104 provided through 103.

A control pressure chamber 140 is formed by the cylinder block 101 and the front housing 102, and a drive shaft 110 is provided so as to traverse the inside of the control pressure chamber 140.
A swash plate 111 is disposed in the control pressure chamber 140. A through hole 111b is formed at the center of the swash plate 111, and the drive shaft 110 is inserted through the through hole 111b. The swash plate 111 is connected to a rotor 112 fixed to the drive shaft 110 via a link mechanism 120 as a connecting means. As a result, the swash plate 111 rotates with the drive shaft 110, and the inclination angle of the swash plate 111 can be changed along the drive shaft 110.

The link mechanism 120 includes a first arm 112 a projecting from the rotor 112, a second arm 111 a projecting from the swash plate 111, and one end pivotable to the first arm 112 a via the first connecting pin 122. And a link arm 121 having the other end rotatably connected to the second arm 111a via a second connection pin 123.

The through hole 111b of the swash plate 111 is formed in a shape that allows the swash plate 111 to tilt within a range from the maximum inclination angle to the minimum inclination angle. In the present embodiment, the through hole 111b is formed with a minimum inclination angle restricting portion that restricts the inclination angle displacement (tilting) of the swash plate 111 in the direction of decreasing the inclination angle by coming into contact with the drive shaft 110. For example, when the inclination angle of the swash plate when the swash plate 111 is orthogonal to the drive shaft 110 is set to 0 degree (minimum inclination angle), the minimum inclination angle restricting section is configured such that the inclination angle of the swash plate 111 is substantially 0 degree. It is formed so as to allow tilt angle displacement (tilt) until. Further, the tilt angle displacement (tilt) of the swash plate 111 in the direction of increasing the tilt angle is regulated by the swash plate 111 coming into contact with the rotor 112. Therefore, the inclination angle of the swash plate 111 becomes the maximum inclination angle when the swash plate 111 contacts the rotor 112.

The drive shaft 110 includes a tilt angle reducing spring 114 that biases the swash plate 111 in a direction that decreases the tilt angle, and a tilt angle increasing spring that biases the swash plate 111 in a direction that increases the tilt angle. 111 is mounted. Specifically, the inclination angle decreasing spring 114 is mounted between the swash plate 111 and the rotor 112, and the inclination angle increasing spring 115 is fixed to or formed on the swash plate 111 and the drive shaft 110. 116.

Here, when the inclination angle of the swash plate 111 is the minimum inclination angle, the urging force of the inclination angle increasing spring 115 is set to be larger than the urging force of the inclination angle decreasing spring 114. For this reason, when the drive shaft 110 is not rotating, that is, when the variable displacement compressor 100 is stopped, the swash plate 111 is biased by the inclination angle decreasing spring 114 and the urging force of the inclination angle increasing spring 115. Are located at an inclination angle (> minimum inclination angle) in which they are balanced. The inclination angle at which the urging force of the inclination angle decreasing spring 114 and the urging force of the inclination angle increasing spring 115 are balanced is set as the minimum inclination angle range in which the compression operation by the piston 136 is ensured. Can be set to a range of degrees.

One end of the drive shaft 110 extends through the boss portion 102a of the front housing 102 to the outside of the front housing 102, and is connected to a power transmission device (not shown). A shaft sealing device 130 is inserted between the drive shaft 110 and the boss portion 102a, and the inside of the control pressure chamber 140 is blocked from the external space.

The drive shaft 110 and the rotor 112 are supported by

bearings

131 and 132 in the radial direction, and supported by a bearing 133 and a thrust plate 134 in the thrust direction. The thrust plate 134 side end of the drive shaft 110 and the thrust plate 134 are adjusted to have a predetermined gap by an adjustment screw 135.
The drive shaft 110 rotates in synchronization with the power transmission device when power from an external drive source (not shown) is transmitted to the power transmission device.

The piston 136 is disposed in the cylinder bore 101a, and one end of the piston 136 protrudes toward the control pressure chamber 140 side. A space is formed inside this end, and the outer periphery of the swash plate 111 is accommodated in the space, and a pair of shoes 137 are disposed across the peripheral portion of the swash plate 111. That is, the swash plate 111 is configured to be interlocked with the piston 136 via a pair of shoes 137. Therefore, the piston 136 can reciprocate in the cylinder bore 101a by the rotation of the swash plate 111.

The cylinder head 104 is formed with a suction chamber 141 disposed in the center and a discharge chamber 142 disposed so as to surround the suction chamber 141 in an annular shape. The suction chamber 141 communicates with each cylinder bore 101a via a communication hole 103a formed in the valve plate 103 and a suction valve (not shown). The discharge chamber 142 communicates with the corresponding cylinder bore 101a via a communication hole 103b formed in the valve plate 103 and a discharge valve (not shown).

Here, the front housing 102, the cylinder block 101, the valve plate 103, and the cylinder head 104 are fastened by a plurality of through bolts 105 through a gasket (not shown) to form a compressor housing.

Also, a discharge muffler is provided on the upper part of the cylinder block 101. The discharge muffler is formed by fastening a lid member 106 in which a discharge port 106 a is formed and a forming wall 101 b that is partitioned and formed on the cylinder block 101 with a bolt through a seal member (not shown). A muffler chamber 143 in the discharge muffler communicates with the discharge chamber 142 via a throttle passage 144. Thus, the discharge chamber 142 is connected to the discharge-side refrigerant circulation path of the air conditioner system via the discharge passage formed by the throttle passage 144, the muffler chamber 143, and the discharge port 106a.

In the cylinder head 104, a suction port 104a and a communication path 104b are formed. The suction chamber 141 is connected to the suction-side refrigerant circulation path of the air conditioner system via a suction passage formed by the suction port 104a and the communication path 104b. Further, the suction passage extends linearly from the outside of the cylinder head 104 toward the suction chamber 141 so as to cross a part of the discharge chamber 142. Here, the discharge chamber 142, the suction chamber 141, the discharge passage, and the suction passage constitute a part of the refrigerant circulation path of the refrigeration cycle.

The cylinder head 104 is further provided with a control valve 300.
The control valve 300 is inserted into a pressure supply passage 145 that connects the discharge chamber 142 and the control pressure chamber 140 via a throttle passage 144 and a muffler chamber 143. The control valve 300 increases the degree of opening of the pressure supply passage 145 in response to the pressure difference between the upstream side (discharge chamber 142) and the downstream side (muffler chamber 143) of the throttle passage 144 and the electromagnetic force generated by the current flowing through the solenoid. The amount of discharge gas introduced into the control pressure chamber 140 is adjusted to control. The refrigerant in the control pressure chamber 140 flows to the suction chamber 141 through the pressure release passage 146 constituted by the communication passage 101c, the space 101d, and the orifice 103c formed in the valve plate 103. Thus, the pressure supply passage 145 and the pressure release passage 146 form a refrigerant circulation path inside the variable capacity compressor 100. For this reason, the pressure of the control pressure chamber 140 changes when the control valve 300 adjusts the opening degree of the supply passage 145. The inclination angle of the swash plate 111, that is, the stroke of the piston 136 is changed by the change in the pressure in the control pressure chamber 140, and the discharge capacity in the variable capacity compressor 100 can be variably controlled.

Next, the control valve 300 will be described more specifically with reference to FIGS. 2 and 3.
FIG. 2 is a cross-sectional view of the control valve 300, and FIG. 3 is a diagram illustrating characteristics of the control valve 300.

The control valve 300 includes a first pressure sensing chamber 302 that is formed in the valve housing 301 and communicates with the discharge chamber 142 via the pressure introduction passage 147 via the communication hole 301a, and the muffler chamber 143 side via the communication hole 301b. A second pressure sensing chamber 303 communicating with the muffler chamber 143 via the pressure supply passage 145; a valve chamber 304 communicating with the control pressure chamber 140 via the pressure supply passage 145 on the control pressure chamber 140 side through the communication hole 301c; A valve hole 301d communicating the pressure sensing chamber 303 and the valve chamber 304; a valve body 305 whose one end is in contact with and away from the valve seat 301e around the valve hole 301d; and opening and closing the valve hole 301d; The second pressure sensitive chamber 303 is partitioned, and the pressure Pd1 of the discharge chamber 142 is received from the first pressure sensitive chamber 302 side, and the pressure Pd2 of the muffler chamber 143 is received from the second pressure sensitive chamber 303 side to discharge pressure. A pressure-sensitive member 306 that is displaced in the opening / closing direction of the valve body 305 in response to a differential pressure (Pd1-Pd2) between two points in the region, and one end side is fixed to the valve body 305 and the other end side is contacted and separated from the pressure-sensitive member 306 A pressure-sensitive rod 307 that is connected to transmit the displacement of the pressure-sensitive member 306 to the valve body 304, a solenoid rod 309 that is integrally formed with the valve body 305 at one end, and the valve body 305 according to the supplied control current. And an actuator 310 that applies an urging force in the valve closing direction. In the control valve 300 configured as described above, the control valve 305 is displaced according to the differential pressure in the discharge pressure region and the biasing force of the actuator 310. The opening of the supply passage 145 is adjusted by the displacement of the control valve 305, and thereby the pressure in the control pressure chamber 140 changes.

The actuator 310 includes a movable iron core 311 press-fitted and fixed to an end opposite to the end integrally formed with the valve body 305 of the solenoid rod 309, and the movable iron core 311 facing the movable iron core 311 with a predetermined gap therebetween. The fixed iron core 312 arranged, the forcible release spring 313 arranged between the fixed iron core 312 and the movable iron core 311 to urge the movable iron core 311 in the valve opening direction, a bottomed cylindrical shape, A housing member 315 that houses the movable iron core 311 and whose opening end is fixed to the solenoid housing 314, and a coil 316 that is housed in the solenoid housing 314 with the housing member 315 inserted therein and whose surface is covered with resin.

The movable iron core 311, the fixed iron core 312 and the solenoid housing 314 are all made of a magnetic material and constitute a magnetic circuit. The housing member 315 is formed of a nonmagnetic material. When a current flows through the coil 316, an electromagnetic force acts between the movable iron core 311 and the fixed iron core 312. This electromagnetic force urges the valve body 305 in the valve closing direction via the solenoid rod 309.

Here, the pressure receiving area Sb of the pressure sensing member 306 in the opening / closing direction of the valve body 305, the pressure receiving area Sv of the pressure Pd1 received by the valve body 305 from the valve hole 301d side, the pressure in the control pressure chamber 140 is Pc, and the actuator 310 The force acting on the valve body 305 is expressed by the following equation (1), where f is the biasing force of the forced opening spring 313, I is the current flowing through the coil 316, and F (I) is the biasing force by the actuator 310. .

Therefore, the control valve 300 has a differential pressure (Pd1−Pd2) between two points in the discharge pressure region by the connecting body of the pressure sensitive member 306, the pressure sensitive rod 307, the valve body 305, the solenoid rod 309 and the movable iron core 311. When the pressure difference becomes smaller than the set differential pressure set based on the current I flowing through the coil 316, the opening of the pressure supply passage 145 is decreased to decrease the pressure in the control pressure chamber 140 in order to increase the discharge capacity. On the other hand, when the differential pressure (Pd1−Pd2) between the two points in the discharge pressure region becomes larger than the set differential pressure, the pressure supply passage 145 is increased to increase the pressure in the control pressure chamber 140 in order to reduce the discharge capacity. . In this way, when the pressure in the control pressure chamber 140 is decreased, the differential pressure between the two points in the discharge pressure region increases and approaches the set differential pressure, and when the pressure in the control pressure chamber is increased, the discharge is performed. The differential pressure between the two points in the pressure region decreases and approaches the set differential pressure. That is, the control valve 300 having the connection body autonomously controls the opening degree of the pressure supply passage 145 so that the differential pressure (Pd1-Pd2) between the two points in the discharge pressure region approaches the set differential pressure. Further, since the two points in the discharge pressure region are set to the refrigerant circulation path (discharge passage) sandwiching the throttle passage 144, the control valve 300 sets the differential pressure between the two points in the discharge pressure region as described above. The refrigerant circulation amount is adjusted by bringing the pressure close to the pressure.
In consideration of the second term (Pd2−Pc) · Sv / Sb on the right side in the above equation (1), the set differential pressure (Pd1−Pd2) on the left side is affected by Pd2−Pc, but Sb >> Sv Therefore, the effect is small.

When the coil 316 is energized, an electromagnetic force acts on the valve body 305 via the solenoid rod 309 in the valve closing direction, that is, a force acts so as to reduce the opening of the pressure supply passage 145. When the energization amount to the coil 316 increases, the force to reduce the opening of the pressure supply passage 145 increases, so that the set differential pressure increases in the direction as shown in FIG.

Note that the actuator 310 in the present embodiment is driven by pulse width modulation (PWM control) at a predetermined frequency in the range of, for example, 400 Hz to 500 Hz, and the pulse width (PWM) so that the current value of the coil 316 becomes a desired value. A device whose duty ratio is changed can be applied.

Next, a discharge capacity control system 400 according to an embodiment of the present invention will be described with reference to FIG.
FIG. 4 is a block diagram showing the configuration of the discharge capacity control system 400.
The discharge capacity control system 400 controls the discharge capacity of the variable capacity compressor 100. In this embodiment, the control valve 300, the A / C switch 401, the rotation sensor 404, and the temperature as temperature detection means. A sensor 402, a pressure sensor 403 as pressure detecting means, and a control current supply means 410 are provided.

The A / C switch 401 sets operation (ON) and non-operation (OFF) of the discharge capacity control system 400. The A / C switch 401 is signal-connected to a control current setting unit 413 of a control current supply unit 410 described later.

The temperature sensor 402 is installed at the evaporator outlet and detects the evaporator outlet air temperature Te. The temperature sensor 402 is connected to a pressure setting unit 412 described later, and outputs the detected evaporator outlet air temperature Te to the pressure setting unit 412.

The pressure sensor 403 detects the pressure in the low pressure region from the evaporator outlet of the air conditioner system to the variable capacity compressor 100 in the refrigerant circuit. For example, the pressure sensor 403 detects the pressure Ps in the suction pressure region. Here, the suction pressure region refers to the suction chamber 141, the communication path 104 b, the suction port 104 a, and the external refrigerant circulation path in the vicinity of the variable capacity compressor 100. The pressure sensor 403 is connected in signal to a control current setting unit 413 described later, and outputs the detected pressure Ps in the suction pressure region to the control current setting unit 413. Further, since the pressure Ps in the suction pressure region is detected, the pressure sensor 403 can quickly respond to a change in discharge volume.

The control current supply unit 410 sets a control current in the control valve 300 and supplies the control current to the actuator 310. The control current supply unit 410 includes an evaporator target temperature setting unit 411 that sets a target value of the evaporator outlet air temperature, and a suction pressure region. A pressure setting means 412 for setting a target value of pressure, a control current setting means 413 for setting a control current I flowing in the coil 316 of the actuator 310, a current detection means 415 for detecting a current flowing in the coil 316, and a coil 316 It has a drive means 414 for adjusting the flowing control current I and a diode 416 arranged in parallel with the coil 316.

The evaporator target temperature setting means 411 is signal-connected to an air conditioning setting means (not shown), an outside air temperature sensor, etc., and outputs various external information such as an air conditioning setting such as a vehicle interior temperature setting and an outside air temperature outputted from these. Based on this, the target value Tes of the evaporator outlet air temperature, which is the final target of the discharge capacity control, is set. The evaporator target temperature setting unit 411 is connected in signal to a pressure setting unit 412 described later, and outputs a target value Tes to the pressure setting unit 412.

The pressure setting unit 412 is based on a deviation ΔT between the target value Tes set by the evaporator target temperature setting unit 411 and the actual evaporator outlet air temperature Te detected by the temperature sensor 402, for example, by PI control. The target value Pss of the pressure in the suction pressure region is set so that the deviation ΔT becomes small. The pressure setting unit 412 is connected to the control current setting unit 413 in a signal manner, and outputs the target value Pss of the pressure in the suction pressure region to the control current setting unit 413.

Here, in the pressure setting means 412, an upper limit value PssH and a lower limit value PssL are set for the target value Pss of the pressure in the suction pressure region. Further, for example, as shown in FIG. 5, the pressure setting unit 412 is in a high rotation speed region where the rotation speed Nc exceeds a predetermined value Nc1 due to the output of the rotation sensor 404 that detects the rotation speed of the variable capacity compressor 100. The lower limit value PssL can be increased from PssL1 to PssL2. Thereby, it is possible to avoid an increase in the discharge capacity in the high rotation speed region. The predetermined value Nc1 is set, for example, as the upper limit (about 5000 rpm) of the normal rotation speed. In the discharge capacity control system according to the present invention, the rotation speed of the variable capacity compressor 100 may be calculated from the rotation speed of the vehicle engine without providing the rotation sensor.

Further, the pressure setting means 412 sets either PssL1 or PssL2 as the lower limit value according to the output value Nc of the rotation sensor 404 as described above. As the output value Nc of 404 becomes higher, a higher lower limit value may be selected. Further, the pressure setting means 412 may use a value calculated based on the output value Nc of the rotation sensor 404 or the rotation speed of the variable capacity compressor calculated from the rotation speed of the vehicle engine as the lower limit value. In the pressure setting means 412, the lower limit value PssL can be changed based on the rotational speed of the variable capacity compressor, but in addition to this, the lower limit value PssL can be changed based on other external information such as the outside air temperature and the operating conditions of the air conditioner system. It may be possible.

When the signal-connected A / C switch 401 is switched from OFF to ON, the control current setting unit 413 performs start-up control that sets the control current I as a function of the elapsed time t from when the signal is connected. . Then, the control current setting unit 413 ends the start-up control when a predetermined time has elapsed, and performs air-conditioning control that sets the control current I based on the operating conditions of the air-conditioning system. The operating conditions of the air conditioner system include, for example, the pressure in the suction pressure region, the target value of the pressure in the suction pressure region, the evaporator air temperature, the target air temperature of the evaporator, other data detected by various air conditioner systems, various target values, etc. It is. The air conditioning control is performed, for example, by PI control based on a deviation ΔPs between the pressure Ps in the suction pressure region detected by the pressure sensor 403 and the target value Pss of the pressure in the suction pressure region set by the pressure setting unit 412. The control current I is set so that the deviation ΔPs becomes small. Further, the control current I is set so that the deviation ΔT is directly reduced from the deviation ΔT between the target value Tes set by the evaporator target temperature setting means 411 and the evaporator outlet air temperature Te detected by the temperature sensor 402. You may do it.

The driving unit 414 includes a switching element driven by pulse width modulation control at a predetermined driving frequency (for example, 400 to 500 Hz), and based on the control current I set by the control current setting unit 413 using this switching element. Thus, the duty ratio is adjusted so that the current flowing through the coil 316 detected by the current detection means 415 approaches the control current I.

The control current supply means 410 configured as described above sets a control current based on the operating condition of the air conditioner system and supplies it to the actuator 310. In the control current supply means 410, the lower limit value PssL is set to the target value Pss of the pressure in the suction pressure region as described above. As a result, the control current supply means 410 sets the target value in the suction pressure region to a value that is equal to or greater than PssL when the pressure in the suction pressure region, which is the low pressure region of the refrigerant circuit, falls below the preset lower limit value PssL. Then, the control current is set to increase the pressure in the control pressure chamber 140 to increase the pressure in the suction pressure region. Then, the discharge capacity decreases as the pressure in the control pressure chamber 140 increases. That is, the control current supply unit 410 sets the control current so as to decrease the discharge capacity and supplies the control current to the actuator 310 when the pressure in the suction pressure region falls below the preset lower limit value PssL.

Here, the operation of the discharge capacity control system 400 described above will be described with reference to FIGS.
FIG. 6 shows a control flow of the discharge capacity control system 400.
The discharge capacity control system 400 has a variable F1, can measure time t with a timer, and initial conditions F1 = 0 and t = 0 are set in advance.

The discharge capacity control system 400 first determines whether the A / C switch 401 is ON or OFF (S101). If the A / C switch 401 is ON, the output value of each sensor connected to the discharge capacity control system 400, the air conditioner setting set by the external device, etc. are read (S102). Next, it is determined whether F1 is 1 (S103). Since F1 = 0 in the initial condition, the result is No, and the process proceeds to S104. In S104, the timer is started and the time t from when the A / C switch 401 is turned on is measured.

Next, the discharge capacity control system 400 sets the control current I of the coil 316 by start control in S105. The control current I by the start control is set as a function of the time t measured by a timer, for example, as shown in FIG. Further, the initial value I0 of the control current at time t = 0 is set as the lower limit value Imin of the control current. Then, the discharge volume control system 400 determines whether or not the time t is less than t1 (S106). If the time t is less than t1, the time t becomes t1 or exceeds t1 (time is up). The activation control is continued by repeating S108 to S112 and S101 to S103 described later. When the timer expires, the discharge capacity control system 400 ends the start-up control (S106), and sets F1 = 1 and t = 0 (S107). After the start-up control is completed, it is determined whether or not F1 is 1 in S103. Since F1 = 1, the process proceeds to S200, and the control current I is set by air conditioning control described in detail later.
When the A / C switch 401 is turned off (S101), the discharge capacity control system 400 sets F1 = 0 and t = 0, that is, initializes the values of F1 and time t (S114), and ends the control flow. Let

Here, in the start-up control and the air conditioning control, the discharge capacity control system 400 compares and determines the control current calculated in each control with a preset lower limit value Imin (S108). The lower limit value Imin is set as the control current I (S109). When the calculated control current is larger than the lower limit value Imin, the calculated control current is compared with a preset upper limit value Imax (> Imin) (S110), and the calculated control current is determined to be the upper limit value Imax. If so, the upper limit value Imax is set as the control current I (S111). When the calculated control current is between the lower limit value Imin and the upper limit Imax, the calculated control current is set as the control current I (S112). Next, the set control current I is output to the coil 316 of the control valve 300 (S113). Then, the process returns to step 101 described above. In this way, the discharge capacity control system 400 repeats the above control until the power is turned off and the process ends.

Here, the air conditioning control in S200 will be described in detail below with reference to FIG.
FIG. 8 is a diagram showing an air conditioning control flow (S200) in the control flow of FIG.
First, the discharge capacity control system 400 calculates a deviation ΔT between the target value Tes of the evaporator outlet air temperature set in the air conditioning control in S200 and the evaporator outlet air temperature Te detected and read by the temperature sensor 402 (S201). ) Based on the deviation ΔT, for example, by PI control, the target pressure value of the pressure in the suction pressure region that is the control target is calculated so that the deviation ΔT becomes small (S202).

In the discharge capacity control system 400, as described above, the lower limit value PssL and the upper limit value PssH are set in advance for the target value Pss of the pressure in the suction pressure region. Then, the discharge capacity control system 400 compares and determines the target pressure value calculated in S202 with a preset lower limit value PssL (S203), and when the calculated target pressure value is less than or equal to the lower limit value PssL, The lower limit value PssL is set as the target value Pss (S204). As shown in FIG. 5, either one of PssL1 and PssL2 is set as the lower limit value PssL according to the output value Nc of the rotation sensor 404.

Further, when the target pressure value calculated in S202 is larger than the lower limit value PssL, the discharge capacity control system 400 compares with the preset upper limit value PssH (S205), and the calculated target pressure value is the upper limit value. If it is equal to or greater than the value PssH, the upper limit value PssH is set as the target value Pss of the suction pressure region (S206).

If the target value calculated in S202 is between the lower limit value PssL and the upper limit PssH, the discharge capacity control system 400 sets the calculated target value as the target value Pss of the pressure in the suction pressure region ( S207).

Next, a deviation ΔPs between the pressure Ps in the suction pressure region detected by the pressure sensor 403 and the target value Pss of the pressure in the suction pressure region set by the pressure setting means 412 is calculated (S208), and the absolute value of the deviation ΔPs is calculated. Is determined (S209). If the absolute value of the deviation ΔPs is equal to or smaller than the preset value α, the current control current I is set as the control current I (S210). That is, the current control current I is maintained. If the absolute value of the deviation ΔPs is larger than the value α, the control current I is set so that the deviation ΔPs becomes smaller, for example, by PI control (S211).

The operation of the discharge capacity control system 400 described above will be described.
When the A / C switch is switched from OFF to ON, the capacity control system 400 executes the start-up control until time t1, and the control valve 300 has a differential pressure (Pd1-Pd2) between two points in the discharge pressure region. The opening degree of the pressure supply passage 145 is autonomously controlled so as to approach the set differential pressure set by the control current I. In such control, since the control current I increases proportionally as the time t increases, the discharge capacity is controlled to gradually increase from the minimum capacity side with time. Then, when the timer expires and the start-up control ends, air conditioning control is executed. In this air conditioning control, the deviation ΔT is reduced based on the deviation ΔT between the target temperature Tes set by the evaporator target temperature setting means 411 and the evaporator outlet air temperature Te detected by the temperature sensor 402. Then, the target value of the pressure in the suction pressure region that is the control target is calculated. The calculated target value of the pressure in the suction pressure region is compared with the lower limit value PssL and the upper limit value PssH, and the target value Pss of the pressure in the suction pressure region is set between the lower limit value PssL and the upper limit value PssH as described above. The Next, the discharge capacity is adjusted so that the pressure Ps in the suction pressure region detected by the pressure sensor 403 approaches the target value Pss in the suction pressure region. As a result, the evaporator outlet air temperature Te approaches the target value Tes. Note that the pressure Ps in the suction pressure region is controlled within a range of ± α with respect to the target value Pss of the suction pressure region.

As described above, since the lower limit value PssL is set in advance for the target pressure value Pss in the suction pressure region, when the pressure Ps in the suction pressure region is lower than the lower limit value, the control current is adjusted to supply the pressure. By increasing the opening of the passage 145 and increasing the pressure in the control pressure chamber 140, the discharge capacity is reliably reduced. Thereby, large-capacity operation in a refrigerant shortage state can be avoided reliably. When the engine speed exceeds the normal rotation speed and becomes the high rotation speed area, the lower limit value PssL is changed to a higher value, thereby increasing the lower limit value of the pressure in the suction pressure area and increasing the discharge capacity in the high rotation speed area. To avoid.

Further, since the upper limit value PssH is set in advance for the target value Pss of the pressure in the suction pressure region, when the pressure Ps in the suction pressure region exceeds the upper limit value, the discharge capacity is increased and the suction pressure region is excessively exceeded. It is avoided that the pressure Ps increases.

In the air conditioning control, in a state where an arbitrary control current I is set, the differential pressure (Pd1−Pd2) between two points in the discharge pressure region is set by the control current I supplied to the coil 316. The discharge capacity is autonomously controlled so as to be a pressure. Thereby, the discharge capacity is stably controlled by the autonomous adjustment function of the control valve 300 and does not become unstable. The discharge capacity control system 400 according to the present invention electrically detects the pressure Ps in the suction pressure region, and the differential pressure between the two points (Pd1−Pd2) is set by the control current I supplied to the coil 316. Since the discharge capacity is controlled by using the control valve 300 that opens and closes the valve hole so as to be the pressure, the discharge capacity can be freely controlled in the range from the minimum capacity to the maximum capacity of the variable capacity compressor 100. .

The control valve 300 in the present embodiment has a structure that has a valve body that responds to the differential pressure between two points in the discharge pressure region, and this is the differential pressure between the two points in the suction pressure region, the discharge pressure region and the suction pressure. Within the variable capacity compressor, such as the differential pressure between the two points of the region, the differential pressure between the two points of the discharge pressure region and the control pressure chamber, or the differential pressure between the two points of the control pressure chamber and the suction pressure region. It is good also as a control valve which has a valve body which responds to the differential pressure between two points of a refrigerant circuit. The pressure-sensitive member may be a columnar member that receives different pressures at both ends, instead of pressure-sensitive means such as bellows or diaphragm. Moreover, the structure in which the valve body and the pressure-sensitive member were formed integrally may be sufficient.

The variable capacity compressor in the present embodiment is a reciprocating compressor, but may be a variable capacity compressor such as a vane or a scroll.

Furthermore, the refrigerant in the present invention is not limited to R134a conventionally used, but may be a refrigerant such as R1234yf or carbon dioxide.

DESCRIPTION OF SYMBOLS 100 ... Variable capacity compressor, 140 ... Control pressure chamber, 142 ... Discharge chamber, 145 ... Pressure supply passage, 305 ... Valve body, 306 ... Pressure-sensitive member, 310 ... Actuator, 403 ... Pressure detection means (pressure sensor), 410 ... Control current supply means

Claims

A variable capacity compressor that is inserted into a refrigerant circulation path through which refrigerant circulates to constitute a refrigeration cycle of an air conditioner system together with a radiator, an expander, and an evaporator, and whose discharge capacity changes based on a change in pressure in a control pressure chamber A system for controlling the discharge capacity,
A pressure-sensitive member that is displaced in the opening and closing direction of the valve body in response to a differential pressure between two points in the refrigerant circulation path inside the variable capacity compressor, and a valve closing direction in the valve body in accordance with the supplied control current. An actuator for applying an urging force, and the valve body is displaced according to the differential pressure between the two points and the urging force of the actuator, and a pressure supply passage that communicates the discharge chamber and the control pressure chamber. A control valve for adjusting the opening to change the pressure in the control pressure chamber;
Pressure detecting means for detecting pressure in a low pressure region of the refrigerant circuit;
Control current supply means for setting the control current to reduce the discharge capacity when the pressure in the low pressure region of the refrigerant circuit is lower than a preset lower limit, and supplying the control current to the actuator;
A discharge capacity control system for a variable capacity compressor.
The discharge capacity control system for a variable capacity compressor according to claim 1, wherein the lower limit value is changed according to the number of rotations of the variable capacity compressor.
The control current supply means includes
A target pressure value in the low pressure region is calculated based on operating conditions of the air conditioner system, and when the calculated target pressure value is smaller than the lower limit value, the lower limit value is set as a target value for the pressure in the low pressure region. And a pressure setting means for setting the calculated target pressure value as a target value of the pressure in the low pressure region when the calculated target pressure value is equal to or greater than the lower limit value,
The discharge capacity control system of a variable capacity compressor according to claim 1 or 2, wherein the control current is set based on a deviation between the detected pressure in the low pressure region and a target value of the set pressure in the low pressure region.
The discharge capacity control system for a variable capacity compressor according to claim 3, wherein the control current supply means maintains the current control current when the deviation is smaller than a preset value.
The discharge capacity control system for a variable capacity compressor according to any one of claims 1 to 4, wherein the refrigerant is carbon dioxide.