JP2002070730A - Pressure controller for variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To linearize the change of a crank chamber pressure corresponding to the change of a supplied control signal in a pressure controller for a variable displacement compressor. SOLUTION: A pressure controlling valve comprises a low pressure chamber 73 communicating with a suction space 36 via a low pressure side connecting hole 72, a high pressure chamber 84 communicating with a discharge space 37 via a high pressure side connecting hole 83, a pressure adjustment chamber 86 communicating with a crank chamber 34 via a crank chamber connecting hole 85, and a valve element 90 for simultaneously opening and closing the passage between the pressure adjustment chamber 86 and the low pressure chamber 73, and the passage between the pressure adjustment chamber 86 and the high pressure chamber 84, according to the controlling signal from outside. The relation among the minimum sectional area S1 of the passage running from the high pressure side connecting hole 83 to the crank chamber connecting hole 85 and the minimum sectional area S2 of the passage running from the crank chamber connecting hole 85 to the low pressure side connecting hole 72 are set, and the ratio R of S1 to S2 is determined to satisfy an inequality of 0.1 mm2<=S1<=1.0 mm2, 0.3 mm2<=S2<=2.0 mm2, 0.1<=S1/S2<=0.7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a drive swash plate fixed to a drive shaft so as to be tiltable, and a piston for varying the volume of the compression chamber by rotation of the drive swash plate. The present invention relates to a pressure control device for a variable displacement compressor in which the inclination angle of a drive swash plate is changed by adjusting a pressure difference from a back pressure of a piston, thereby making it possible to change a piston stroke and thereby change a discharge capacity. .

[0002]

2. Description of the Related Art A pressure control valve used in a variable displacement swash plate type compressor disclosed in Japanese Patent Application Laid-Open No. 5-99136 discloses a first control for opening and closing communication between a discharge chamber and a crank chamber. A valve, a second control valve that controls opening and closing of the communication between the crank chamber and the suction chamber, a transmission rod that operates the first and second control valves, and an electromagnetic actuator that moves the transmission rod. The second under the pressure in the suction chamber
And a pressure-sensitive member (diaphragm, bellows, etc.) for operating the control valve.

Further, a control valve for a variable displacement compressor disclosed in Japanese Patent Application Laid-Open No. 9-268974 discloses a valve element which opens and closes an air supply passage communicating a discharge pressure region with a crank chamber. One side is operatively connected via a pressure-sensitive rod and is housed in a pressure-sensitive chamber communicated with a suction pressure area, and in a direction in which the opening degree of the air supply passage decreases as the pressure in the suction pressure area increases. A pressure-sensitive portion for urging the valve body is operatively connected to the other side of the valve body via a solenoid rod, and when the solenoid is excited, a load is applied to the valve body in a direction to reduce an opening degree of an air supply passage. And a forcible opening means for urging the valve body in a direction for forcibly opening the air supply passage by demagnetizing the solenoid, and connecting and disconnecting the valve body and the pressure-sensitive part. It is connected as much as possible.

For this reason, if the pressure-sensitive chamber is under a high suction pressure condition in a state where the solenoid of the solenoid portion is demagnetized, the pressure-sensitive portion is displaced in a direction to decrease the opening of the air supply passage. Since the biasing force acting on the valve body by the forcible opening means and the displacement by the pressure-sensitive portion are in directions away from each other,
Since the pressure sensing part and the valve element are separated from each other, the maximum opening position of the valve element is maintained. It is disclosed that the pressure-sensitive portion is a bellows, and that the pressure-sensitive portion may be a diaphragm.

[0005]

However, when a control valve using a diaphragm or a bellows as a pressure-sensitive element in a pressure-sensitive section as shown in the above-mentioned reference is used in a refrigeration cycle using carbon dioxide as a refrigerant, Since the pressure in the cycle is about 10 times that of the conventional refrigeration cycle using chlorofluorocarbon, it is difficult to satisfy the pressure resistance of the pressure-sensitive element. Since it is necessary to operate the electromagnetic force against high pressure, a problem occurs that the size of the electromagnetic actuator itself becomes large.

For this reason, the applicant of the present invention has a sufficient pressure resistance against the pressure of a refrigeration cycle using carbon dioxide as a refrigerant, and performs the variable displacement control reliably without enlarging the pressure control valve. An application for a pressure control device capable of reducing pressure has been filed earlier. By the way, in constructing such a pressure control device, a change in the crank chamber pressure with respect to a change in the supplied control signal is represented by a solid line (characteristic line I) in FIG.
It is desirable for the control to make the change as linear as possible, as shown by. This is because, as shown by the broken line in FIG. 7, the crank chamber pressure rises or falls at a stretch by a slight change of the control signal, and thereafter, even if the control signal is changed, the crank chamber pressure does not change. For example, it is difficult to control the discharge capacity in the variable intermediate range.

Accordingly, the present invention relates to a variable displacement compressor capable of linearly changing a crank chamber pressure in response to a change in a supplied control signal when constructing a compact pressure control valve having a pressure-resistant specification. It is an object to provide a pressure control device.

[0008]

In order to achieve the above object, a pressure control device for a variable displacement compressor according to the present invention comprises a cylinder block, a drive shaft provided in the cylinder block, and a rotary shaft which rotates together with the drive shaft. A drive swash plate having a variable inclination angle with respect to a drive shaft, a plurality of cylinders provided in the cylinder block and having an axis parallel to the drive shaft, and slidably disposed on the cylinder; A plurality of pistons reciprocating in the cylinder as the plate rotates, a compression chamber defined by the cylinder and the piston, a crank chamber formed on the side of the piston opposite the compression chamber, and a suction stroke of the piston And at least a suction space communicating with the compression chamber, and a discharge space communicating with the compression chamber in the compression stroke of the piston. A pressure control device for a variable displacement compressor, which is used for a displacement type compressor and controls the pressure in the crank chamber to change the inclination angle of the drive swash plate. A low-pressure chamber that communicates with the discharge space via a low-pressure communication hole, a high-pressure chamber that communicates with the discharge space via a high-pressure communication hole, and a pressure that communicates with the crank chamber via a crank chamber communication hole. An adjustment chamber, a valve body for opening / closing between the pressure adjustment chamber and the low-pressure chamber, and simultaneously closing / opening between the pressure adjustment chamber and the high-pressure chamber, and an electromagnetic coil for generating an electromagnetic force. A plunger that is slidably inserted into the electromagnetic coil and moves by the electromagnetic force of the electromagnetic coil to move the valve body; and a spring that urges the valve body in a direction opposite to the direction of urging by the plunger. And the pressure adjusting chamber and When the space between the low-pressure chamber is closed and the space between the pressure adjustment chamber and the high-pressure chamber is open, the minimum passage cross-sectional area S1 of the path from the high-pressure side communication hole to the crank chamber communication hole, the pressure adjustment A low pressure side communication hole communicating with the suction space from a crank chamber communication hole communicating with the crank chamber when the space between the chamber and the low pressure chamber is opened and the pressure adjustment chamber and the high pressure chamber are closed. The minimum passage cross-sectional area S2 of the route to be reached and the ratio R between the S1 and the S2 are 0.1 mm ² ≦ S1 ≦ 1.0 mm
² , 0.3mm ² ≦ S2 ≦ 2.0mm ² , 0.1 ≦ S1
/S2≦0.7 is satisfied (claim 1).

Therefore, according to the above configuration, since the valve body is moved by controlling the electromagnetic coil, a portion having low pressure resistance, such as a conventional low-pressure pressure detecting portion, can be omitted, and the refrigeration system can be used. The pressure resistance to the cycle pressure can be increased, and the minimum passage cross-sectional area S1 of the path from the high-pressure side communication hole to the crank chamber communication hole and the minimum path cross-section from the crank chamber communication hole to the low pressure side communication hole Since the passage cross-sectional area S2 and the ratio R between S1 and S2 are set within the above-described ranges, the characteristics shown by the solid line in FIG. 7 can be obtained.

In particular, such a pressure control device includes a variable displacement compressor, a radiator for cooling the refrigerant compressed thereby, an expansion device for reducing the pressure of the refrigerant cooled by the radiator, and an expansion device. An evaporator that evaporates the refrigerant decompressed by the apparatus is used in a refrigeration cycle in which carbon dioxide is used as the refrigerant, and the pressure of a low-pressure line from the outlet side of the expansion device to the variable displacement compressor is set to a target pressure. If the pressure is higher than the target pressure, open the space between the pressure adjustment chamber and the low-pressure chamber, and move the valve body in a direction to close the space between the pressure adjustment chamber and the high-pressure chamber. If the pressure is too low, a control signal is supplied to the electromagnetic coil so as to close the gap between the pressure adjustment chamber and the low pressure chamber and move the valve body in a direction to open the gap between the pressure adjustment chamber and the high pressure chamber. It is suitable for such cases ( Motomeko 2). At this time, the control signal supplied to the electromagnetic coil may control the duty ratio of energization of the electromagnetic coil.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a refrigeration cycle 1
Is a variable displacement compressor (hereinafter referred to as a compressor) 3 having a pressure control valve 2 for varying a discharge capacity and capable of compressing a refrigerant to a supercritical region, a radiator 4 for cooling the refrigerant, a high pressure line An internal heat exchanger 5 for exchanging heat between the refrigerant and the low pressure line, an expansion device 6 for decompressing the refrigerant, an evaporator 7 for evaporating and evaporating the refrigerant, and an accumulator 8 for separating the refrigerant flowing out of the evaporator 7 into gas and liquid. It is configured. In the refrigeration cycle 1, the discharge side of the compressor 3 is connected to the high-pressure passage 5a of the internal heat exchanger 5 via the radiator 4, and the outlet side of the high-pressure passage 5a is connected to the expansion device 6, and the compressor 3 The high-pressure line 9 is a path extending from the discharge side to the expansion device 6. The outlet side of the expansion device 6 is connected to an evaporator 7, and the outlet side of the evaporator 7 is connected to a low-pressure passage 5 b of the internal heat exchanger 5 via an accumulator 8. The outflow side of the low-pressure passage 5 b is connected to the suction side of the compressor 3, and the path from the outflow side of the expansion device 6 to the compressor 3 is a low-pressure line 10.

In the refrigeration cycle 1, carbon dioxide (CO ₂ ) is used as a refrigerant, and the refrigerant compressed by the compressor 3 enters a radiator 4 as a high-temperature and high-pressure supercritical refrigerant. To dissipate heat and cool. Thereafter, the internal heat exchanger 5 exchanges heat with the low-temperature refrigerant flowing out of the evaporator 7 to be further cooled and sent to the expansion device 6 without being liquefied. Then, the pressure is reduced in the expansion device 6 to become a low-temperature and low-pressure wet steam, and heat exchange with the air passing therethrough in the evaporator 7 to form a gaseous state. It is heated by heat exchange and returned to the compressor 3.

From the outlet side of the expansion device 6, the compressor 3
A pressure sensor 12 for detecting a low pressure is provided in the low pressure line 10 between the suction sides of the pressure sensors. This pressure sensor 1
The low-pressure pressure Ps detected by the control unit 2 includes a temperature sensor 13 for detecting the outside air temperature Ta, a temperature sensor 14 for detecting the vehicle interior temperature Tinc, a temperature setting signal Tset from a temperature setting device 15 of an operation panel (not shown), and an amount of solar radiation The information is input to the control unit 17 together with the amount of solar radiation Qsun detected by the detection sensor 16 and the like.

The control unit 17 includes an input circuit 18 for inputting various signals described above as data, a read-only memory (ROM), and a random access memory (R).
AM), a central processing unit (CPU) that calls a program stored in the memory unit 19 to process the data, and saves the data to the memory unit 19 to calculate control data. 20) an output circuit 21 for outputting a duty ratio of a control signal based on the control data calculated by the central processing unit 20; a constant voltage circuit 23 for producing a desired constant voltage from a battery power supply 22; 23, and a duty ratio control circuit 24 that outputs a control signal having a duty ratio output from the output circuit 21.

The compressor 3 is, for example, a variable displacement swash plate type compressor as shown in FIG. 2. The outer peripheral block 30 of the compressor 3 includes a front block 31 defining a crank chamber 34, and a plurality of cylinders. It comprises a central block 32 defining a space 35, and a rear block 33 defining a suction space 36 and a discharge space 37.

A drive shaft 38 disposed through the outer peripheral block 30 is rotatably held by the front block 31 and the center block 32 via bearings 39a and 39b. The engine is connected to a running engine via a belt, a pulley, and an electromagnetic clutch, and when the electromagnetic clutch is turned on, the rotation of the engine is transmitted and rotated. Also,
The drive shaft 38 rotates with the rotation of the drive shaft 38,
A swash plate 40 is provided which can be inclined with respect to the drive shaft 38.

A plurality of cylinders 35 formed in the central block 32 are formed around the drive shaft 38 at predetermined intervals, and are formed in a cylindrical shape having a central axis parallel to the axis of the drive shaft 38. The cylinder 35
, A piston 41 whose one end is held by the swash plate 40 is slidably inserted.

In the above configuration, when the drive shaft 38 rotates, the swash plate 40 rotates with a predetermined inclination.
The end of the swash plate 40 swings at a predetermined width in the axial direction of the drive shaft 38. As a result, the piston 41 fixed to the radial end portion of the swash plate 40 reciprocates in the axial direction of the drive shaft 38 to change the volume of the compression chamber 42 defined in the cylinder 35, The refrigerant is sucked from the suction space 36 through a suction port 43 having a suction valve 44, and the compressed refrigerant is discharged to a discharge space 37 through a discharge port 45 having a discharge valve 46.

The displacement of the compressor 3 is determined by the stroke of the piston 41. The stroke is determined by the pressure applied to the front of the piston 41, ie, the pressure of the compression chamber 42, and the pressure applied to the back of the piston, ie, the crank chamber 34.
It is determined by the pressure difference between the internal pressure (crank chamber pressure). Specifically, if the pressure in the crank chamber 34 is increased, the differential pressure between the compression chamber 42 and the crank chamber 34 is reduced, so that the inclination angle (swing angle) of the swash plate 40 is reduced.
For this reason, the stroke of the piston 41 is reduced and the discharge capacity is reduced. Conversely, if the pressure in the crank chamber 34 is reduced, the differential pressure between the compression chamber 42 and the crank chamber 34 increases, so that the swash plate 40 The inclination angle (oscillation angle) increases, so that the stroke of the piston 41 increases and the discharge capacity increases.

The pressure in the crank chamber 34 is controlled by a pressure control valve 2 provided in a rear block 33 of the compressor 3. The pressure control valve 2 is specifically as shown in FIGS. 3 and 4 and includes a drive unit 60, a central block unit 70, and a valve body unit 80.

The driving unit 60 is provided with the central block 7
0, a cylindrical case 61 housed in the case 61 and fixed to one end of the central block 70, and a cylindrical case 62 wound around the cylinder 62. And one end face which is slidably inserted into the cylinder 62 and abuts the valve drive rod 68 on the side of the central block 70 and the other end face on which a spring mounting hole 65 is formed. A plunger 64, a spring 66 inserted into the spring mounting hole 65, one end of which contacts the plunger 64, and the case holding the other end of the spring 66 and sealing the other end of the cylinder 63. And a cover 67 fixed to the other end of the cover 61.

The central block 70 includes a cylindrical projection 71a for fixing the cylinder 63 and the case 61.
A cylindrical block 71 having an outer ring portion 71b to which it is caulked and fixed at one end side;
And a through-hole 74 through which the valve body drive rod 68 slidably passes, a low-pressure chamber 73 formed in the center of the block 71 in a cylindrical shape, and extends radially from the low-pressure chamber 73. It has a plurality of low pressure side communication holes 72. still,
The plurality of low pressure side communication holes 72 are formed in the suction space 3 of the compressor 3 through first grooves 75 formed in the rear block 33.
6, the pressure in the low-pressure chamber 73 substantially matches the pressure in the low-pressure line of the refrigeration cycle 1.

The valve body 80 includes a substantially cylindrical outer case 81 and an inner case 8 mounted on the outer case 81.
A pressure adjustment chamber 86 is formed on the central block side of the outer case 81, and an opening / closing portion 91 of a valve body 90 is housed therein.
Is slidably inserted. A high-pressure chamber 84 is defined between the small diameter portion 92 of the valve element formed between the opening / closing portion 91 of the valve element and the sliding portion 93 and the inner case 82. The pressure adjustment chamber 86 communicates with the crank chamber 34 via a crank chamber communication hole 85 opened in the outer case 81 and a second groove 95 formed in the rear block 33. It communicates with the discharge space 37 via a high-pressure side communication hole 83 formed through the outer case 81 and the inner case 82 and a third groove 96 formed in the rear block 33.

The inner diameter of the pressure adjusting chamber 86 is the same as that of the low pressure chamber 7.
3, the inner diameter of the inner case 82 is smaller than the inner diameter of the pressure adjustment chamber 86, and the outer diameter of the opening / closing portion 91 accommodated in the pressure adjustment chamber 86 is smaller than that of the low pressure chamber 73. The inner diameter is formed larger than the inner diameter and the inner diameter of the inner case 82.
A low-pressure side valve seat 76 on which a valve body 90 is seated is formed between the pressure adjusting chamber 86 and the pressure adjusting chamber 86 (the low pressure chamber 73 faces the opening of the pressure adjusting chamber 86). A high-pressure side valve seat 77 on which the valve element 90 is seated is formed between the valve body 86 and the high pressure chamber 86 (the periphery of an opening portion where the high pressure chamber 84 faces the pressure adjustment chamber 86). Therefore, the opening / closing portion 91 of the valve element 90 housed in the pressure adjustment chamber 86 is seated on the low-pressure side valve seat 76 or the high-pressure side valve seat 77, so that the pressure adjustment chamber 8
6 and the low-pressure chamber 73 or the high-pressure chamber 84 are communicated (open) or shut off (closed).

A low-pressure space 87 is formed between the end of the sliding portion 93 of the valve element 90 and the inner case 82, and a cover 89 for fixing the inner case 82 to the outer case 81 is formed. It communicates with the suction space 36 through the formed communication hole 88 and the communication space 97 formed in the rear block 33. The low-pressure space 87 accommodates a spring 94 that urges the valve body 90 to press the low-pressure side valve seat 76. Incidentally, the urging force of the spring 94 is set to be larger than the urging force of the spring 66, and when the electromagnetic coil 63 is not energized, as shown in FIG. It comes into contact with the side valve seat 76.

Therefore, since a low pressure can be applied to both end surfaces in the moving direction of the valve body 90, there is no pressure difference between both ends in the moving direction of the valve body 90, so that the valve body 90 can be moved smoothly. Since the driving force of the valve body 90 can be suppressed, the size of the electromagnetic coil 63 itself can be suppressed.

When the pressure Ps detected by the pressure sensor 12 is higher than the target pressure Psa by the control unit 17 for such a pressure control valve 2,
The pressure control valve 2 is operated in a direction to increase the discharge capacity of the compressor 3, and when the detected pressure Ps of the pressure sensor 12 is smaller than the target pressure Psa, the pressure control valve 2 is moved in a direction to decrease the discharge capacity of the compressor 3. Control for operating the pressure control valve 2 is performed. That is, based on the low pressure Ps and the target pressure Psa, the duty ratio is calculated from the arithmetic expression shown in Expression 1, and a control signal having this duty ratio is formed by the duty ratio control circuit 24. In the following Equation 1, A is a proportional constant, B is an integral constant, and C is a correction term. When the low pressure Ps is larger than the target pressure Psa, the duty ratio becomes large.
A control signal having a large duty ratio as shown in (a) is supplied to the electromagnetic coil 63 of the pressure control valve 2, and when the low pressure Ps is smaller than the target pressure Psa, the duty ratio becomes small. The control signal having a small duty ratio as shown in FIG.
Is supplied to the electromagnetic coil 63.

[0028]

(Equation 1)

Here, a predetermined fixed value may be used as the target pressure Psa, or the outside air temperature Ta and the vehicle interior temperature Tin.
c, Psa = K6 · F (H) + K7 based on the heat load H calculated from the solar radiation Qsun, the set temperature Tset, and the like.
May be determined. Note that K6 is an operation constant, and K7 is a correction term.

Therefore, the detection pressure P of the pressure sensor 12
If s is higher than the target pressure Psa, the pressure control valve 2
A control signal having a large duty ratio is supplied to the electromagnetic coil 63, and the plunger 64 is attracted to the electromagnetic coil 63 to move the valve element 90 via the valve element driving rod 68 against the spring force of the spring 94. For this reason, the opening / closing part 91 is seated on the high-pressure side valve seat 77, and becomes the state shown in FIG. As a result, the crank chamber 34 communicates with the suction space 36 via the pressure adjusting chamber 86 and the low-pressure chamber 73 and has the same pressure as the low-pressure pressure. And the discharge capacity of the compressor 3 increases.

When the pressure Ps detected by the pressure sensor 12 is lower than the target pressure Psa, a control signal having a small duty ratio is supplied to the electromagnetic coil 63 of the pressure control valve 2 and the plunger 64 is energized. The spring force of the spring 94 exceeds the electromagnetic force, and the opening / closing portion 91 is moved to the low pressure side valve seat 76.
And the state shown in FIG. 3 is obtained. As a result, the crank chamber 34 communicates with the discharge space 37 via the pressure adjusting chamber 86 and the high-pressure chamber 84 and becomes the same pressure as the high-pressure pressure. Becomes smaller, and the discharge capacity of the compressor 3 decreases.

By the way, in the pressure control valve 2 having the above configuration, the space between the pressure adjustment chamber 86 and the low pressure chamber 73 is closed, and the space between the pressure adjustment chamber 86 and the high pressure chamber 84 is opened. In the state shown in FIG. 3, the minimum passage cross-sectional area S1 of the passage from the high-pressure side communication hole 83 to the crank chamber communication hole 85 is set to be in a range represented by the following Expression 2.

[0033]

[Equation 2] 0.1 mm ² ≦ S1 ≦ 1.0 mm ²

Here, the minimum passage cross-sectional area S1 means that the ease with which the refrigerant flows from the discharge space 37 to the crank chamber 34 is determined by the high pressure side communication hole 83 of the pressure control valve 2 and the crank chamber communication hole 85.
Is determined by the narrowest part of the route to
This indicates the cross-sectional area of the passage at the most narrowed portion. As shown in FIG. 6A, the most narrowed portion in this case is the high pressure side communication hole 83 or the inner case from the high pressure side communication hole 83 of the high pressure chamber 84 to the pressure adjustment chamber 86. A ring-shaped passage 1 between the valve body 82 and the small-diameter portion 92 of the valve body 90
00, the passage 101 between the opening / closing section 91 and the high-pressure side valve seat 77, or the crank chamber communication hole 85, for example, the inner case 82 and the valve body 90
If the ring-shaped passage 100 between the ring-shaped passage 92 and the small-diameter portion 92 is the most narrowed portion, the inner diameter of the inner case 82 is adjusted so that the cross-sectional area of the ring-shaped passage 100 is 0.1 to 1.0 mm ² And the diameter of the small diameter portion 92 is set.

In the state shown in FIG. 4 in which the space between the pressure adjustment chamber 86 and the low-pressure chamber 73 is open and the space between the pressure adjustment chamber 86 and the high-pressure chamber 84 is closed, The minimum passage cross-sectional area S2 of the passage leading to the communication hole 72 is
It is set so as to be in the range shown by the following Equation 3.

[0036]

[Equation 3] 0.3 mm ² ≦ S2 ≦ 2.0 mm ²

Here, the minimum passage cross-sectional area S2 means that the ease with which the refrigerant flows from the crank chamber 34 to the suction space 36 is determined by the low pressure side communication hole 72 and the crank chamber communication hole 85 of the pressure control valve 2.
Is determined by the narrowest part of the route to
This indicates the cross-sectional area of the passage at the most narrowed portion. As shown in FIG. 6B, the most narrowed portion in this case is the crank chamber communication hole 85 or the opening / closing portion 9.
1 and the passage 102 between the low pressure side valve seat 76,
The ring-shaped passage 103 between the block 71 and the valve body drive rod 68 from the pressure adjustment chamber 86 of the low-pressure chamber 73 to the low-pressure communication path 72 may be used, or the low-pressure communication hole 72 may be used. For example, if the low-pressure side communication hole 72 is the most narrowed portion, the passage diameter is set so that the passage cross-sectional area of the low-pressure side communication hole 72 is 0.3 to 2.0 mm ² .

Further, after setting S1 and S2 within the above-described range, the ratio R between S1 and S2 is set so as to satisfy the relationship shown in Expression 4.

[0039]

## EQU4 ## 0.1 ≦ R = S1 / S2 ≦ 0.7

The above settings are made for the following reasons. First, the lower limit of the minimum passage cross-sectional area S1 at the most narrowed portion of the path from the high-pressure side communication hole 83 to the crank chamber communication hole 85 is set to 0.1 mm ^2. 91 is seated on the low-pressure side valve seat 76 to close the space between the pressure adjustment chamber 86 and the low-pressure chamber 73.
In a state shown in FIG. 3 in which the space between the pressure chamber and the high pressure chamber 84 is opened, the refrigerant does not flow smoothly from the discharge space 37 to the crank chamber 34, and it takes time for the crank chamber pressure to rise. This is because it was confirmed by experiments.

The reason why the upper limit of S1 is set to 1.0 mm ² is that if the minimum passage sectional area S1 is larger than this, the flow of refrigerant from the discharge space 37 into the crank chamber 34 becomes unnecessarily large. Due to a slight change in the control signal input to the pressure control valve 2, that is, a slight change in the duty ratio, the crank chamber pressure rises rapidly and the piston 4
1 de-strokes, and after that, even if the control signal is changed, the crank chamber pressure is kept constant at a high state.
This is because the characteristic becomes as shown in the following, and therefore, the capacity control becomes impossible in the variable intermediate region of the control signal, and the control range is substantially narrowed.

That is, the lower limit value of S1 is a limit value for preventing the response from being deteriorated beyond the allowable range, and the upper limit value is a condition where the response is too good to control. As a limit value that can avoid
Each was determined by experiment.

Next, the lower limit of the minimum passage cross-sectional area S2 at the most narrowed portion of the path from the crank chamber communication hole 85 to the low pressure side communication hole 72 is set to 0.3 mm ^2. The opening / closing section 91 is seated on the high-pressure side valve seat 77 to open between the pressure adjusting chamber 86 and the low-pressure chamber 73.
In the state shown in FIG. 4 in which the space between the pressure chamber 6 and the high-pressure chamber 84 is closed, the refrigerant does not quickly move from the crank chamber 34 to the suction space 36, so that the pressure in the crank chamber hardly decreases, and This is because it has been confirmed by experiments that a phenomenon in which the back pressure of the stroked piston is difficult to decrease and the discharge capacity cannot be rapidly increased, that is, the startability is deteriorated.

The reason why the upper limit of S1 is set to 2.0 mm ² is that if the minimum passage cross-sectional area S2 is larger than this, the outflow of refrigerant from the crank chamber 34 to the suction space 36 becomes larger than necessary. A slight change in the control signal input to the pressure control valve 2, i.e., a slight change in the duty ratio, causes a sudden drop in the crank chamber pressure and a full stroke of the piston at a stretch. Even if the crankcase pressure is low, it becomes constant even in Fig. 7
, The capacity cannot be controlled in the variable intermediate region of the control signal, and the control range is substantially narrowed.

That is, the lower limit value of S2 is a limit value for preventing the response from deteriorating beyond the allowable range and deteriorating the startability, and the upper limit is controlled because the response is too good. The limit values that can avoid the difficult state are respectively determined by experiments.

By setting the minimum passage cross-sectional area of each path in the above-described range as described above, it is only necessary to define conditions for optimally designing each path independently. And the ratio R between S2 and 0.1 ≦ R =
It is necessary to set S1 / S2 ≦ 0.7 for the following reason.

First, a state where the control signal input to the pressure control valve 2 has a value that increases the piston stroke (in this example, a control signal having a large duty ratio is supplied and the opening / closing section 91 is shown in FIG. In a positional relationship)
(In this example, a control signal having a small duty ratio is supplied and the opening / closing section 91 changes to the state shown in FIG. 3). When a certain time has elapsed in the state shown in FIG. 4, the pressure difference between the high-pressure line 9 and the low-pressure line 10 is large, and when the opening / closing section 91 moves from this state to the state shown in FIG. Since the pressure difference between the pressure of the crank chamber 34 and the pressure of the crank chamber 34 is large, even if S1 is small, the crank chamber 3
Since the state is such that the refrigerant easily flows into 4, the S1 may be small as long as it satisfies the above range.

On the other hand, the control signal is changed from a state in which the compressor is stopped (a state in which the opening / closing section 91 is in the positional relationship shown in FIG. 3) to a value in which the compressor is started to increase the piston stroke. (In this example, a case where the control signal having a large duty ratio is supplied and the opening / closing section 91 changes to the state of the positional relationship shown in FIG. 4) is assumed. When the passage has elapsed, the pressure difference between the high-pressure line 9 and the low-pressure line 10 is almost zero, and even when the opening / closing section 91 moves from this state to the state shown in FIG. Since there is almost no pressure difference from the pressure at 36, the state is such that the refrigerant hardly flows out from the crank chamber to the suction space. For this reason, there is a demand to make S2 as large as possible in order to make the refrigerant easily flow from the crank chamber 34 to the suction space 36.

From the above, it has been found that S2 needs to be larger than S1.
Regarding whether 2 needs to be larger than S1,
According to experiments by the inventors, the ratio R between S1 and S2 is 0.1
If it is smaller than the discharge space 37, the crank chamber 34
It is difficult for the refrigerant to enter the piston 41, and it is difficult to immediately destroke the piston 41 because it deviates from the characteristic line shown by the solid line in FIG. 7. When R becomes larger than 0.7, the pressure in the crank chamber 34 is sucked. Because it ’s easier to get into space 36,
Even if a control signal for slightly changing the piston stroke in the full stroke direction is input, the crank chamber pressure drops at a stretch and the piston 41 switches to the full stroke, deviating from the characteristic line shown by the solid line in FIG. It became clear. Therefore, when the piston stroke is changed in the de-stroke direction and when the piston stroke is changed in the full-stroke direction, it is necessary to secure appropriate control. Therefore, it is necessary to set S1 and S2 within the ranges of Expressions 2 and 3. However, it has been found that the ratio R between S1 and S2 must be further set in the range of Expression 4.

As described above, when S1 and S2 are smaller than the above-mentioned ranges, the speed of change of the crank chamber pressure becomes slow, and the variable responsiveness is deteriorated. Increases, the rate of change of the crank chamber pressure becomes too fast, making the control difficult. When R is not set within the above-described range, the duty ratio of the pressure control valve 2 is controlled. , It becomes impossible to linearly control the crank chamber pressure with respect to the duty ratio. Therefore, by setting each of S1, S2, and R as described above, the control signal input to the pressure control valve 2 is controlled. The whole range (duty ratio 0% to 10
0%), the responsiveness can be appropriately set, and the relationship between the control signal indicated by the solid line in FIG. 7 and the crank chamber pressure can be made substantially linear. .

[0051]

As described above, according to the present invention, there is provided a pressure control device for a variable displacement compressor which can change the inclination angle of the drive swash plate by controlling the pressure in the crank chamber. A low-pressure chamber communicating with the suction space via the low-pressure communication hole, a high-pressure chamber communicating with the discharge space via the high-pressure communication hole, and a crank chamber communicating with the crank chamber via the crank chamber communication hole. A pressure regulating chamber, a valve body that opens / closes between the pressure regulating chamber and the low-pressure chamber, and simultaneously closes / opens between the pressure regulating chamber and the high-pressure chamber, and an electromagnetic coil that generates an electromagnetic force; At least a plunger slidably inserted into the electromagnetic coil and moved by the electromagnetic force of the electromagnetic coil to move the valve element, and a spring for urging the valve element in a direction opposite to the urging direction of the plunger. Between the pressure adjustment chamber and the low pressure chamber Closed, minimum passage cross-sectional area S1 of the path from the high pressure side communication hole to the crank chamber communication hole when opening between the pressure adjustment chamber and the high pressure chamber, opening between the pressure adjustment chamber and the low pressure chamber, pressure adjustment When the space between the chamber and the high-pressure chamber is closed, the minimum passage cross-sectional area S2 of the path from the crank chamber communication hole communicating with the crank chamber to the low-pressure communication hole communicating with the suction space, and the ratio of S1 to S2 R is 0.1 mm ²
≦ S1 ≦ 1.0mm ² , 0.3mm ² ≦ S2 ≦ 2.0m
m ² , 0.1 ≦ R = S1 / S2 ≦ 0.7 The relationship is set so as to satisfy a relationship of 0.1 ≦ R = S1 / S2 ≦ 0.7. On the other hand, it is possible to provide a pressure control device for a variable displacement compressor capable of linearly changing the crank chamber pressure.

In particular, such a pressure control device is used in a refrigeration cycle in which a variable displacement compressor uses carbon dioxide as a refrigerant, and the pressure of a low pressure line from the outlet side of the expansion device to the variable displacement compressor is targeted. When the pressure is higher than the pressure, the valve body is moved in a direction to open between the pressure adjustment chamber and the low pressure chamber and close the pressure adjustment chamber and the high pressure chamber, and the pressure of the low pressure line becomes equal to the target pressure. If it is lower, the control signal to the electromagnetic coil is closed so that the valve body is moved in a direction to close the pressure adjustment chamber and the low pressure chamber and open the pressure adjustment chamber and the high pressure chamber. It is suitable for controlling.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a sectional view of the variable displacement compressor according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a state where power is not supplied to the pressure control valve according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a state when power is supplied to the pressure control valve according to the embodiment of the present invention.

FIG. 5 is a diagram showing an example of a control signal supplied to the pressure control valve. FIG. 5 (a) shows a control signal having a large duty ratio, and FIG. 5 (b) shows a control signal having a small duty ratio. Indicates a signal.

6 (a) is an enlarged cross-sectional view showing the vicinity of the opening / closing part in the state of the pressure control valve in FIG. 3, and FIG. 5 (b)
FIG. 5 is an enlarged sectional view showing the vicinity of an opening / closing unit in a state of the pressure control valve in FIG. 4.

FIG. 7 is a characteristic diagram showing a relationship between a control signal (duty ratio) input to the pressure control valve and a crankcase pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Pressure control valve 3 Compressor 4 Radiator 5 Internal heat exchanger 6 Expansion device 7 Evaporator 8 Accumulator 10 Low pressure line 12 Pressure sensor 31 Front block 32 Central block 33 Rear block 34 Crank chamber 35 Cylinder 36 Suction space 37 Discharge space 40 Swash plate 41 Piston 42 Compression chamber 63 Electromagnetic coil 64 Plunger 72 Low pressure side communication hole 73 Low pressure chamber 83 High pressure side communication hole 84 High pressure chamber 85 Crank chamber communication hole 86 Pressure adjustment chamber 90 Valve element 91 Opening / closing part 94 Spring

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenji Iijima 39, Higashihara, Chiyo-ji, Konan-cho, Osato-gun, Saitama Prefecture F term (reference) 3H045 AA04 AA12 AA27 BA14 BA20 CA02 CA13 CA24 CA29 DA25 DA43 DA47 EA13 EA16 EA26 EA33 EA38 EA42 3H076 AA06 AA40 BB32 BB43 CC05 CC12 CC20 CC28 CC84 CC91

Claims (3)

[Claims] 1. A cylinder block, a drive shaft provided in the cylinder block, a drive swash plate that rotates with the drive shaft and has a variable inclination angle with respect to the drive shaft.
A plurality of cylinders provided in the cylinder block and having an axis parallel to the drive shaft; a plurality of pistons slidably disposed in the cylinder and reciprocating in the cylinder with rotation of the drive swash plate; A compression chamber defined by the cylinder and the piston, a crank chamber formed on the side of the piston opposite to the compression chamber, a suction space communicating with the compression chamber in a suction stroke of the piston, and compression of the piston. Used in a variable displacement compressor having at least a discharge space communicating with the compression chamber in the stroke,
In a pressure control device for a variable displacement compressor, wherein a pressure in the crank chamber is controlled to change a tilt angle of the drive swash plate, at least communication with the suction space through a low-pressure side communication hole is provided. A low-pressure chamber, a high-pressure chamber communicating with the discharge space through a high-pressure communication hole, a pressure adjustment chamber communicating with the crank chamber through a crank chamber communication hole, the pressure adjustment chamber, At the same time as opening / closing between the low pressure chamber and
A valve body that closes / opens between the pressure adjustment chamber and the high-pressure chamber, an electromagnetic coil that generates an electromagnetic force, and is slidably inserted into the electromagnetic coil and moves by the electromagnetic force of the electromagnetic coil. A plunger for moving the valve body in a direction opposite to a direction in which the valve body is biased by the plunger. The pressure adjustment chamber is closed between the pressure adjustment chamber and the low-pressure chamber. A minimum passage cross-sectional area S1 of a path from the high-pressure side communication hole to the crank chamber communication hole when the space between the pressure adjustment chamber and the high-pressure chamber is opened; A minimum passage cross-sectional area S2 of a path from a crank chamber communication hole communicating with the crank chamber to a low-pressure communication hole communicating with the suction space when the space between the adjustment chamber and the high-pressure chamber is closed; And the ratio R of
But characterized in that it is set so as to satisfy the relationship of ^{0.1mm 2 ≦ S1 ≦ 1.0mm 2 0.3mm} 2 ≦ S2 ≦ 2.0mm 2 0.1 ≦ R = S1 / S2 ≦ 0.7 Pressure control device for a variable displacement compressor. 2. The variable displacement compressor includes a radiator that cools the refrigerant compressed by the compressor, an expansion device that decompresses the refrigerant cooled by the radiator, and a refrigerant that is depressurized by the expansion device. An evaporator that evaporates is used in a refrigeration cycle in which carbon dioxide is used as the refrigerant, the pressure of a low-pressure line from the outlet side of the expansion device to the variable displacement compressor being higher than a target pressure. Is also high, open the space between the pressure adjustment chamber and the low-pressure chamber, and move the valve body in a direction to close the space between the pressure adjustment chamber and the high-pressure chamber, the low-pressure line When the pressure is lower than the target pressure, the valve body is moved in a direction that closes the space between the pressure adjustment chamber and the low pressure chamber and opens the space between the pressure adjustment chamber and the high pressure chamber. So that the control signal is the electromagnetic coil 2. The pressure control device for a variable displacement compressor according to claim 1, wherein the pressure is supplied to the compressor. 3. A pressure control valve for a variable displacement compressor according to claim 2, wherein the control signal supplied to said electromagnetic coil controls duty ratio of energization of said electromagnetic coil.