WO2010041775A1

WO2010041775A1 - Variable capacity compressor

Info

Publication number: WO2010041775A1
Application number: PCT/JP2009/067964
Authority: WO
Inventors: 幸彦田口
Original assignee: サンデン株式会社
Priority date: 2008-10-09
Filing date: 2009-10-09
Publication date: 2010-04-15
Also published as: US20110194951A1; JP5142212B2; DE112009002441T5; JP2010090834A

Abstract

A variable capacity compressor provided with a capacity control valve capable of easily adjusting to an optimum level the sensitivity to a rise in the pressure in a crank chamber. A variable capacity compressor configured in such a manner that the stroke of a piston is changed by adjusting the pressure in a crank chamber, the pressure in the crank chamber being changed by adjusting the degree of opening of a capacity control valve for opening and closing a path for interconnecting a discharge chamber and a crank chamber, wherein the capacity control valve is provided with a valve chamber communicating with the discharge chamber, a valve hole, a valve element for opening and closing the valve hole, a pressure sensing chamber communicating with a suction chamber, a pressure sensing member provided in the pressure sensing chamber, and a pressure sensing rod having one end connected to the pressure sensing member and the other end connected to the valve element and driving the valve element in response to displacement of the pressure sensing member. The pressure in the crank chamber acts on the valve element from the valve hole side in the direction of opening of the valve element, and acts on the pressure sensing rod from the valve hole side in the direction of closing of the valve element. That area (Sr) of the pressure sensing rod which receives the pressure in the crank chamber is set to be greater than that area (Sv) of the valve element which receives the pressure in the crank chamber.

Description

Variable capacity compressor

The present invention relates to a variable capacity compressor, and more particularly to a variable capacity compressor suitable for use in a refrigeration circuit of a vehicle air conditioner.

A capacity control valve that opens and closes a supply passage that communicates between the discharge chamber and the crank chamber by sensing suction pressure; and a throttle that is disposed in a bleed passage that communicates between the crank chamber and the suction chamber. A variable capacity compressor is known in which the pressure in the crank chamber is changed by adjusting the opening, and the stroke of the reciprocating motion of the piston is adjusted to compress the refrigerant sucked into the cylinder bore from the suction chamber and discharge it into the discharge chamber ( For example, Patent Document 1). Such a variable capacity compressor is provided, for example, in a refrigeration circuit of a vehicle air conditioner and is used as a refrigerant compressor. A small amount of the refrigerant gas throttled by the throttle through the extraction passage is extracted from the crank chamber, and the refrigerant gas in the discharge chamber is introduced into the crank chamber controlled by adjusting the opening of the capacity control valve. The pressure is controlled to the target pressure, whereby the stroke of the piston is adjusted via the tilt angle control of the swash plate element, and the discharge capacity of the compressor is controlled to the target capacity.
Japanese Patent Laid-Open No. 62-282182

In the variable capacity compressor as described above, the valve body of the capacity control valve opens and closes the air supply passage in response to the displacement of the pressure-sensitive member (for example, a diaphragm) that senses the suction pressure, but the discharge pressure is high. Since the amount of discharge gas introduced into the crank chamber is greatly different even when the discharge pressure is low, the throttle placed in the bleed passage that connects the crank chamber and the suction chamber is fixed at a fixed opening. In some cases, the pressure increase sensitivity of the crank chamber pressure (that is, the change amount of the crank chamber pressure with respect to the change amount of the suction pressure) also greatly changes.
In particular, when the discharge pressure is high, the amount of discharge gas introduced into the crank chamber increases, so the pressure increase sensitivity of the crank chamber pressure tends to increase, but if the pressure increase sensitivity of the crank chamber pressure increases excessively, the discharge capacity increases. It may decrease excessively and the operation of the valve body may become unstable, causing a so-called hunting phenomenon. When such a hunting phenomenon occurs, for example, in the air conditioning control by the vehicle air conditioner using this variable capacity compressor, the temperature fluctuation in the passenger compartment occurs, which not only adversely affects the air conditioning control but also the compressor torque. If the compressor is driven by an engine, the engine control may be adversely affected.
Accordingly, an object of the present invention is to provide a variable displacement compressor including a displacement control valve that can easily adjust the pressure increase sensitivity of the crank chamber pressure to an optimum sensitivity.

In order to solve the above problems, a variable capacity compressor according to the present invention includes a housing in which a discharge chamber, a suction chamber, a crank chamber, and a cylinder bore are defined, a piston inserted into the cylinder bore, and the housing The discharge shaft and the crank chamber are communicated with each other, a drive shaft rotatably supported therein, a motion conversion mechanism including a variable swash plate element that converts the rotation of the drive shaft into a reciprocating motion of the piston, and the discharge chamber. A capacity control valve that opens and closes the air supply passage; and a throttle element disposed in a bleed passage that connects the crank chamber and the suction chamber, and changes the pressure in the crank chamber by adjusting the opening of the capacity control valve. Adjusting the stroke of the reciprocating motion of the piston, and by reciprocating the piston, sucking the refrigerant from the suction chamber into the cylinder bore and compressing the sucked refrigerant, In the variable capacity compressor that discharges into the outlet chamber, the capacity control valve includes a valve chamber that communicates with the discharge chamber, a valve hole that communicates with the valve chamber at one end, and a valve hole that communicates with the crank chamber at the other end. A valve seat that faces the valve chamber and is formed around the valve hole; a valve body that is disposed in the valve chamber and that opens and closes the valve hole by contacting and separating from the valve seat; and the suction chamber A pressure sensing chamber communicating with the pressure sensing member, a pressure sensing member disposed in the pressure sensing chamber and displaced in response to the pressure in the suction chamber, one end connected to the pressure sensing member, and the other end to the valve hole side A pressure-sensitive rod connected to the valve body and driving the valve body in response to displacement of the pressure-sensitive member, and the pressure in the crank chamber is applied to the valve body from the valve hole side. Acts in the direction of opening the valve body, and the pressure in the crank chamber acts on the pressure sensitive rod in the direction of closing the valve body from the valve hole side. In both cases, Sr and Sv are satisfied so that Sr> Sv is satisfied, where Sr is a pressure receiving area where the pressure sensing rod receives the pressure of the crank chamber and Sv is a pressure receiving area where the valve body receives the pressure of the crank chamber. Is set.
In such a variable capacity compressor according to the present invention, the pressure-receiving area Sr that receives the crank chamber pressure of the pressure-sensitive rod that acts in the direction in which the valve body is closed acts in the direction in which the valve body is opened. By setting the chamber pressure larger than the pressure receiving area Sv, the crank chamber pressure always acts in the direction of closing the valve body. The state in which the crank chamber pressure always acts in the direction in which the valve body is closed does not basically change even if the discharge pressure changes, so the crank chamber pressure increase sensitivity (that is, the crank chamber pressure relative to the amount of change in the suction pressure) Can be changed by appropriately adjusting the pressure receiving area of each part for opening and closing the valve body, and by appropriately setting the pressure receiving area of each part, the opening and closing operation of the valve body can be changed. It is possible to stabilize (that is, a stable operation that does not cause the hunting phenomenon as described above) and improve the suction pressure control accuracy. In practice, it is possible to satisfy the above Sr> Sv simply by changing the pressure receiving area of the crank chamber pressure of the pressure sensitive rod without changing other parts. It becomes possible to adjust the pressure increase sensitivity of the chamber pressure, and it is possible to stabilize the opening / closing state of the valve body and obtain a stable discharge capacity control state.
In the variable capacity compressor according to the present invention, the pressure in the discharge chamber acts on the valve body in a direction to close the valve body, and the pressure receiving area where the pressure-sensitive member receives the pressure in the suction chamber is Sb. In this case, Sr, Sv, and Sb may be set so as to satisfy Sb + Sv> 2Sr. In such an embodiment, the suction pressure control accuracy can be improved particularly in the case of a capacity control valve structure in which the pressure in the discharge chamber acts in the direction of closing the valve body.
In the variable capacity compressor according to the present invention, the capacity control valve further includes a pressure chamber communicating with the suction chamber, and one end of the valve body abuts and separates from the valve seat and the valve hole And the other end of the valve body is disposed in the pressure chamber so that the pressure in the suction chamber acts in a direction to close the valve body, and the pressure sensing member receives the pressure in the suction chamber. When the area is Sb and the pressure receiving area where the valve body receives the pressure of the suction chamber is Sp, Sr, Sv, Sp and Sb may be set so as to satisfy Sb + Sp + Sv> 2Sr. In such an embodiment, in particular, in the case of a capacity control valve structure in which the pressure in the suction chamber acts in the direction of closing the valve body, it is possible to improve the suction pressure control accuracy.
In the latter embodiment, it is preferable that Sp and Sv are set so that Sp> Sv is satisfied. Thereby, it is possible to suppress the valve body from opening excessively when the discharge capacity is reduced, and it is possible to further stabilize the opening / closing operation of the valve body.
Further, the throttle element arranged in the extraction passage can be a throttle element whose opening degree can be adjusted. However, the present invention is particularly effective when the opening degree is a fixed orifice. That is, in the present invention, by applying the structure according to the present invention, it is possible to easily adjust the pressure increase sensitivity of the crank chamber pressure only by the capacity control valve, so that the crank chamber and the suction chamber communicate with each other. In the case where the throttle element is an orifice having a fixed opening, it is possible to suppress the fluctuation in the pressure increase sensitivity of the crank chamber pressure particularly when the discharge gas introduction amount fluctuates greatly.
The structure of the variable capacity compressor according to the present invention can be applied to any variable capacity compressor in which the stroke of the reciprocating motion of the piston is adjusted by changing the pressure of the crank chamber by adjusting the opening of the capacity control valve. . In particular, it is suitable for a compressor provided in a refrigeration circuit of a vehicle air conditioner, and can suppress the hunting phenomenon of the valve body of the capacity control valve, so that the operation of the valve body can be stabilized. The occurrence of temperature fluctuations in the room can be prevented. Further, since it is possible to suppress the torque fluctuation of the compressor, it is possible to prevent the engine control from being adversely affected particularly when the compressor drive source is an engine.

According to the variable capacity compressor of the present invention, the relationship between the pressure receiving area Sr of the crank chamber pressure of the pressure sensing rod in the capacity control valve and the pressure receiving area Sv of the crank chamber pressure of the valve body is set to Sr> Sv. It is possible to easily adjust the pressure increase sensitivity of the crank chamber pressure, and it is possible to stably perform target capacity control while suppressing the occurrence of the hunting phenomenon of the valve body. In particular, it is possible to easily adjust the pressure increase sensitivity of the crank chamber pressure by simply changing the pressure receiving area of the crank chamber pressure of the pressure sensing rod, and the valve body opening / closing operation is stabilized to obtain a stable discharge capacity control state. be able to.
Further, in the capacity control valve structure in which the pressure in the discharge chamber acts in the direction of closing the valve body, the relationship between the Sr and Sv and the pressure receiving area Sb of the suction chamber pressure of the pressure sensitive member satisfies Sb + Sv> 2Sr. By setting to, the suction pressure control accuracy can be improved.
In the capacity control valve structure in which the pressure in the suction chamber acts in the direction of closing the valve body, the relationship between the above-mentioned Sr, Sv and Sb and the pressure receiving area Sp of the suction chamber pressure of the valve body satisfies Sb + Sp + Sv> 2Sr. By setting in this way, the suction pressure control accuracy can be improved. In particular, if it is set so that Sp> Sv is satisfied, it is possible to prevent the valve body from opening excessively when the discharge capacity is reduced, and to contribute to further stabilization of the opening / closing operation of the valve body.
In the present invention, since the pressure increase sensitivity of the crank chamber pressure can be easily adjusted only by the capacity control valve, the throttle element arranged in the extraction passage that connects the crank chamber and the suction chamber is an orifice whose opening is fixed. In particular, the present invention is particularly effective.

It is a longitudinal section of the variable capacity compressor concerning a 1st embodiment of the present invention. It is the longitudinal cross-sectional view (A) of the capacity control valve in the compressor of FIG. 1, and the partial expanded longitudinal cross-sectional view (B) of the capacity control valve. FIG. 3 is a relationship diagram between a suction pressure and a crank chamber pressure showing an operation at each condition of the capacity control valve of FIG. 2. FIG. 3 is a relationship diagram between discharge pressure and suction pressure showing an example of control characteristics of the capacity control valve of FIG. 2. It is a longitudinal cross-sectional view of the capacity control valve in the variable capacity compressor which concerns on 2nd Embodiment of this invention. FIG. 6 is a relationship diagram between a current of an electromagnetic coil and a control suction pressure showing an example of control characteristics by the capacity control valve of FIG. 5.

DESCRIPTION OF SYMBOLS 100 Variable capacity compressor 101 Cylinder block 101a Cylinder bore 102 Front housing 102a Boss part 103 Valve

plate

103a, 103b Communication hole 103c Fixed orifice 104 Rear housing 104a Suction port 104b Discharge port 105 Crank chamber 106 Drive shaft 107 Swash plate 108 Rotor 109 Connecting

part

110, 111 Coil spring 112

Shaft seal device

113, 114, 115, 116 Bearing 117 Piston 118 Shoe 119 Suction chamber 120

Discharge chamber

121, 121a, 121b Air supply passage 122 Space 123 Communication passage 200 Capacity control valve 210 Valve

housing

210a, 210b Valve housing component 211 Pressure sensing chamber 212 Communication hole 213 Valve chamber 214 Valve hole 215 Communication hole 216 Valve seat 217 Insertion hole 218 Positioning Hole 220 Valve body 230 Pressure sensitive rod 240 Bellows assembly 241 as pressure sensitive member Bellows 242 End member 243 Guide member 244 Positioning member 245 Compression coil spring 250 Spring 260 Spring guide 261

Communication holes

270, 271, 272 Seal member 300 Capacity Control valve 301 Valve

housing

301a, 301c, 301d, 301e Communication hole 301b Valve hole 302 Pressure sensing chamber 303 Bellows assembly 304 Pressure sensing rod 304a Valve body 305 Fixed core 305a Support hole 306 Valve chamber 307 Movable core 308 Solenoid rod 309 Spring 310 Solenoid case 311 Non-magnetic sleeve 312 Electromagnetic coil 313 Bellows guide 314 Pressure setting member 315 Forced release spring

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
1 to 4 are a longitudinal sectional view of a variable capacity compressor according to a first embodiment of the present invention, a longitudinal sectional view of a capacity control valve used in the variable capacity compressor, and an operation explanatory view thereof.
(1) Structure of variable capacity compressor (Fig. 1)
The 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 rear provided via a valve plate 103 at the other end of the cylinder block 101. The housing 104 is provided, and these constitute the housing referred to in the present invention.
A drive shaft 106 is provided across the crank chamber 105 defined by the cylinder block 101 and the front housing 102, and a swash plate 107 is disposed around the center thereof. The swash plate 107 is coupled to the rotor 108 fixed to the drive shaft 106 via a connecting portion 109, and the inclination angle can be changed along the drive shaft 106. A coil spring 110 is mounted between the rotor 108 and the swash plate 107 to urge the swash plate 107 toward the minimum inclination side, and the swash plate 107 is disposed on the opposite side of the swash plate 107. A coil spring 111 that biases the tilt angle toward the increasing direction is mounted.
One end of the drive shaft 106 extends through the boss portion 102a protruding to the outside of the front housing 102 and extends to the outside, and is connected to an electromagnetic clutch (not shown). A shaft seal device 112 is inserted between the drive shaft 106 and the boss portion 102a to block the inside and outside of the compressor. The drive shaft 106 is supported by

bearings

113, 114, 115, and 116 in the radial direction and the thrust direction, and power from an external drive source (for example, a vehicle engine) is transmitted through an electromagnetic clutch so as to be rotatable. .
A piston 117 is inserted into the cylinder bore 101a so as to be able to reciprocate. The periphery of the outer periphery of the swash plate 107 is accommodated in a recess 117a at one end inside the piston 117. The piston 117 and the swash plate 107 are configured to interlock with each other via a pair of shoes 118 that are in sliding contact. Therefore, the rotation of the drive shaft 106 enables the piston 117 to reciprocate within the cylinder bore 101a, and these series of members constitute the motion conversion mechanism referred to in the present invention.
A suction chamber 119 and a discharge chamber 120 are defined in the rear housing 104. The suction chamber 119 is connected to the cylinder bore 101a through a communication hole 103a (suction hole) provided in the valve plate 103 and a suction valve (not shown). The discharge chamber 120 communicates with the cylinder bore 101a via a discharge valve (not shown) and a communication hole 103b (discharge hole) provided in the valve plate 103. The suction chamber 119 is connected to the air conditioner system side via the suction port 104a, and the discharge chamber 120 is connected to the air conditioner system side via the discharge port 104b.
The rear housing 104 is provided with a capacity control valve 200. The capacity control valve 200 adjusts the opening of an air supply passage 121 (121a, 121b) that communicates the discharge chamber 120 and the crank chamber 105, and controls the amount of discharge gas introduced into the crank chamber 105. In addition, the refrigerant in the crank chamber 105 is sucked into the suction chamber through a bleed passage through a clearance between the outer periphery of the drive shaft 106 and the

bearings

115 and 116, a space 122 and a fixed orifice 103c formed in the valve plate 103 with a fixed opening. It flows to 119. Therefore, the discharge capacity can be controlled by adjusting the discharge gas introduction amount into the crank chamber 105 by the capacity control valve 200 and changing the pressure in the crank chamber 105.
(2) Capacity control valve structure (Fig. 2)
As shown in FIG. 2A, the capacity control valve 200 includes a valve housing 210, a valve body 220, a pressure sensitive rod 230, a bellows assembly 240 as a pressure sensitive member, a spring 250, and a spring guide 260. And sealing

members

270, 271 and 272.
The valve housing 210 includes a member 210a that accommodates the bellows assembly 240 and a member 210b in which the pressure sensitive rod 230 is slidably supported and the valve body 220 is disposed. The member 210b is press-fitted and fixed to the member 210a. ing. The member 210a and the member 210b define a pressure sensitive chamber 211, and the pressure sensitive chamber 211 communicates with the suction chamber 119 via the communication hole 212 and the communication passage 123 (FIG. 1).
A valve chamber 213 is formed in the member 210b, and one of the valve chambers 213 communicates with the discharge chamber 120 via a communication hole 261 and an air supply passage 121a formed in the spring guide 260, and the other of the valve chambers 213 is a valve The crank chamber 105 communicates with the hole 214, the communication hole 215, and the air supply passage 121b.
A valve body 220 is disposed in the valve chamber 213, and the valve body 220 contacts and separates from a valve seat 216 formed around the valve hole 214 to open and close the valve hole 214. One end of the spring 250 abuts on the valve body 220 and the other end abuts on the spring guide 260, and the valve body 220 is urged in the valve closing direction by the urging force of the spring 250. The spring guide 260 is press-fitted and fixed to the peripheral wall of the valve chamber 213.
An insertion hole 217 that slidably supports the pressure-sensitive rod 230 is formed in the member 210b, and a gap between the outer periphery of the pressure-sensitive rod 230 and the insertion hole 217 is set to a minimum, and the pressure-sensitive chamber 211 and the valve hole 214 Is almost airtight.
2B, the bellows assembly 240 is positioned on the bellows 241, the end member 242 that closes both ends of the bellows 241, the guide member 243 that receives one end of the pressure-sensitive rod 230, and the member 210a. And a compression coil spring 245 that is arranged inside the bellows 241 and biases the bellows assembly 240 in the extending direction. The inside of the bellows assembly 240 is maintained in a substantially vacuum state.
The bellows assembly 240 is disposed in the pressure-sensitive chamber 211, and a positioning member 244 is fitted and fixed in a positioning hole 218 formed in the member 210a. The guide member 243 receives one end of the pressure-sensitive rod 230, and the other end of the pressure-sensitive rod 230 contacts the valve body 220 from the valve hole 214 side, so that the valve body 220 corresponds to the expansion and contraction of the bellows assembly 240. Opens and closes the valve hole 214.
The seal member 270 ensures airtightness between the atmosphere side and the region where the pressure of the suction chamber 119 acts, and the seal member 271 is formed between the region where the pressure of the suction chamber 119 acts and the region where the pressure of the crank chamber 105 acts. Further, the seal member 272 ensures airtightness between the region where the crank chamber 105 pressure acts and the region where the discharge chamber 120 pressure acts.
(3) Capacity Control Valve Characteristics The valve body 220 has a pressure in the discharge chamber 120 in the valve closing direction (hereinafter referred to as discharge pressure Pd) and a pressure in the crank chamber 105 in the valve opening direction (hereinafter referred to as crank chamber pressure Pc). ), The crank chamber pressure Pc acts in the valve closing direction on the pressure sensitive rod 230, and the pressure of the suction chamber 119 (hereinafter referred to as the suction pressure Ps) acts in the valve opening direction. The suction pressure Ps acts on the bellows assembly 240 in the valve closing direction.
Here, since the valve seat 216 is an edge portion of the opening end portion of the valve hole 214, the pressure receiving area Sv of the crank chamber pressure Pc acting on the valve body 220 is substantially equal to the cross-sectional area of the valve hole 214. The pressure receiving area Sr of the crank chamber pressure Pc acting on the pressure sensing rod 230 is a cross-sectional area of the pressure sensing rod 230 in a region supported by the insertion hole 217, and is set to Sr> Sv. As a result, the crank chamber pressure Pc always acts in the direction in which the valve body 220 is closed. If the pressure receiving area (effective area) of the suction pressure Ps acting in the expansion / contraction direction of the bellows assembly 240 is Sb, the biasing force of the spring 250 is fs, and the biasing force of the bellows assembly 240 is Fb, it acts on the valve body 220. The force can be expressed by the following formula [Expression 1] (including Formula (1) and Formula (2)).

The meaning of each symbol in the above [Equation 1] is as follows.
Ps: suction pressure Pc: crank chamber pressure Pd: discharge pressure Sv: pressure receiving area of crank chamber pressure acting on the valve body Sr: pressure receiving area of crank chamber pressure acting on the pressure sensing rod Sb: suction acting in the expansion / contraction direction of the bellows Pressure receiving area (effective area)
fs: urging force of the spring 250 Fb: urging force of the bellows assembly 240 In the above equation (2), when Pd is constant, Pc is a linear function of Ps, and Pc decreases as Ps increases. On the other hand, it has a characteristic of increasing as Ps decreases, and its inclination is determined by (Sb−Sr) / (Sr−Sv). That is, the coefficient (Sb−Sr) / (Sr−Sv) of Ps is the sensitivity of Pc change to Ps change.
For example, as shown in FIGS. 3A, 3 </ b> B, and 3 </ b> C, the sensitivity of the crank chamber pressure Pc when the suction pressure Ps changes depending on the magnitude of (Sb−Sr) / (Sr−Sv). Changes. Since Sb, Sv, and Sr are the pressure receiving areas of the respective pressures, the sensitivity of the crank chamber pressure Pc when the suction pressure Ps changes can be adjusted by adjusting the pressure receiving areas.
Here, if (Sb−Sr) / (Sr−Sv) = 1, that is, Sb + Sv = 2Sr, the amount of change in the suction pressure Ps and the amount of change in the crank chamber pressure Pc become equal, and (Sb−Sr) / (Sr -Sv)> 1, the amount of change in the crank chamber pressure Pc relative to the amount of change in the suction pressure Ps increases, and if (Sb-Sr) / (Sr-Sv) <1, the amount of change in the suction pressure Ps. The amount of change in the crank chamber pressure Pc with respect to is reduced.
Therefore, the suction pressure Ps can be accurately controlled by setting Sb, Sr, and Sv so as to satisfy (Sb−Sr) / (Sr−Sv)> 1, that is, Sb + Sv> 2Sr.
Thus, if Sr> Sv, the crank chamber pressure Pc acts in the direction of closing the valve body 220, and as a result, as shown in [Equation 1], the sensitivity of the crank chamber pressure Pc when the suction pressure Ps changes is shown. Can be changed by appropriately adjusting Sb, Sr, and Sv, and the open / closed state of the valve body 220 can be stabilized and the suction pressure control accuracy can be improved.
In the above description, Pd = constant. However, when Pc is a linear function of Ps from Equation (2), Pd is only a parameter, and even if Pd changes, the above description does not change. That is, by setting Sr> Sv, the above actions and effects can be obtained.
(4) Capacity Control Operation of Variable Capacity Compressor Equation (2) is transformed into Equation (3) (the following [Equation 2]). Equation (3) shows the suction pressure control characteristic of the displacement control valve 200, and as shown in FIG. 4, the suction pressure Ps to be controlled is slightly reduced and corrected when the discharge pressure Pd increases.

In the state where the variable capacity compressor 100 is not operating, the refrigerant pressure is balanced. For example, if the outside air temperature is high, the suction pressure Ps is significantly higher than the expression (3). In this case, the bellows assembly 240 is contracted by the force of the suction pressure Ps, whereby the valve body 220 closes the valve hole 214.
When the variable capacity compressor 100 is started from this state, the discharge gas is not introduced into the crank chamber 105, so that the refrigerant gas (blow-by gas) in the crank chamber 105 flows into the suction chamber 119 via the extraction passage, and the crank chamber pressure is increased. Pc becomes equal to the suction pressure Ps. As a result, the inclination angle of the swash plate 107 increases and the piston stroke is maintained at the maximum.
When the suction pressure Ps gradually decreases due to the operation of the variable capacity compressor 100, the bellows assembly 240 expands. When the suction pressure Ps reaches the characteristic of the expression (3), the pressure-sensitive rod 230 pushes up the valve body 220. The valve hole 214 is opened, and as a result, the discharge gas is introduced into the crank chamber 105.
Since the refrigerant flowing out from the crank chamber 105 to the suction chamber 119 is restricted by the fixed orifice 103c of the extraction passage, the crank chamber pressure Pc rises, thereby reducing the inclination angle of the swash plate 107 and reducing the piston stroke.
Note that the degree of increase in the crank chamber pressure Pc, that is, the amount of change in the crank chamber pressure Pc relative to the amount of change in the suction pressure Ps is appropriately adjusted by setting Sb, Sr, and Sv (Sb + Sv> 2Sr).
When the piston stroke decreases, the suction pressure Ps tends to increase, but when the suction pressure Ps increases, the bellows assembly 240 tends to contract, so that the valve body 220 is displaced in the closing direction. As a result, the amount of discharge gas introduced into the crank chamber 105 is reduced and the crank chamber pressure Pc is reduced, so that the reduction of the piston stroke is stopped and the valve body 220 is maintained at a predetermined opening.
If the suction pressure Ps decreases due to some disturbance, the bellows assembly 240 extends again to push up the valve body 220, the amount of discharge gas introduced into the crank chamber 105 is increased, and the crank chamber pressure Pc is increased. The tilt angle of the swash plate 107 is reduced and the piston stroke is reduced.
By such an operation, the piston stroke is controlled so that the suction pressure Ps approaches the suction pressure control characteristic of the above formula (3).
Thus, according to the present invention, as can be seen from the above formula (2), if only the cross-sectional area Sr of the pressure-sensitive rod 230 is changed, the change amount of the crank chamber pressure Pc with respect to the change amount of the suction pressure Ps is changed. Can be made. Therefore, the design changes of the main elements related to the basic structure of the capacity control valve, such as the cross-sectional area Sv of the valve hole 214 that affects the flow characteristics and the pressure receiving area (effective area) Sb of the suction pressure that acts in the expansion and contraction direction of the bellows assembly 240 Even if not, the change amount of the crank chamber pressure Pc with respect to the change amount of the suction pressure Ps can be changed, and the crank chamber pressure boost sensitivity of the capacity control valve can be easily optimized according to various variable capacity compressors. Can be planned. As a result, even when various specifications are required for the capacity control valve, it is possible to share the main elements of the capacity control valve.
[Second Embodiment]
FIG. 5 shows a capacity control valve 300 in the second embodiment of the present invention.
The second embodiment basically differs from the first embodiment described above in that the discharge pressure Pd acts in the direction of closing the valve body in the capacity control valve 200 of FIG. 2, but the capacity control of FIG. The valve 300 has a structure in which the suction pressure Ps acts in the direction in which the valve body is closed, and the discharge pressure Pd does not act on the valve body. In addition, the valve 300 is a capacity control valve by a so-called external control system in which electromagnetic force is applied to the valve body. That is.
Capacity control valve structure:
Referring to FIG. 5, the capacity control valve 300 is disposed in a pressure sensing chamber 302 formed in the valve housing 301, receives the suction pressure through the communication hole 301a and the communication path 123, and evacuates the inside to be a spring. A bellows assembly 303 that functions as a pressure-sensitive member, a pressure-sensitive rod 304 that has one end abutting against the bellows assembly 303 and is slidably supported by the valve housing 301, and the pressure-sensitive rod 304 A valve body 304a that is integrally formed and that has the other end slidably supported by the support hole 305a of the fixed core 305 and that is disposed in the valve chamber 306 and opens and closes the valve hole 301b according to the expansion and contraction of the bellows assembly 303. The solenoid rod 3 has one end abutting against the other end surface of the valve body 304a and the other end fixed to the fixed core 305 and a movable core 307 disposed opposite to the fixed core 305 with a predetermined gap. 8, a spring 309 that presses the movable core 307 in the valve closing direction, an outer peripheral portion of the movable core 307 slidably supported, and a non-magnetic sleeve 311 that is fixed to the solenoid case 310 by inserting the fixed core 305. The coil 312 is disposed outside the sleeve 311 and inside the solenoid case 310 and generates electromagnetic force. The solenoid includes a fixed core 305, a movable core 307, a solenoid rod 308, a sleeve 311, a solenoid case 310, and an electromagnetic coil 312.
Further, the end of the bellows assembly 303 opposite to the pressure-sensitive rod 304 is supported by a bellows guide 313, and the bellows guide 313 is slidably supported by the pressure setting member 314. Further, between the pressure setting member 314 and the bellows guide 313, a forced opening spring 315 that presses the bellows assembly 303 in the valve opening direction is disposed. The pressure setting member 314 is press-fitted and fixed to the valve housing 301 so that the capacity control valve 300 is set to a predetermined pressure.
The valve chamber 306 communicates with the discharge chamber 120 through the communication hole 301c. The valve hole 301b communicates with the crank chamber 105 through a communication hole 301d. Therefore, the communication hole 301 c, the valve chamber 306, the valve hole 301 b, and the communication hole 301 d constitute a part of the air supply passage 121.
The space inside the sleeve 311 in which the movable core 307, the solenoid rod 308, and the surface on the other end side of the valve body 304a are disposed communicates with the pressure sensitive chamber 302 through the communication hole 301e. Therefore, the crank chamber pressure Pc acts on the surface on one end side (valve hole 301b side) of the valve body 304a, and the suction pressure Ps acts on the surface on the other end side of the valve body 304a.
Since the sectional area Sp of the valve body 304a supported by the support hole 305a is set to be slightly larger than the sectional area Sv of the valve hole 301b, the force of the discharge pressure Pd in the valve chamber 306 in the valve opening direction of the valve body 304a. Is acting slightly. Further, the cross-sectional area Sr of the pressure-sensitive rod 304 is set larger than the cross-sectional area Sv of the valve hole 301b, and the crank chamber pressure Pc acts in the direction of closing the valve body.
Therefore, the force acting on the valve body 304a of the capacity control valve 300 can be expressed by the following formula [Expression 3] (including Formula (4) and Formula (5)).
The meanings represented by the symbols in Equation 3 are as follows.
Ps: suction pressure Pc: crank chamber pressure Pd: discharge pressure Sv: pressure receiving area of the crank chamber pressure acting on the valve body Sp: pressure receiving area of the suction pressure acting on the valve body Sr: crank chamber pressure acting on the pressure sensing rod Pressure receiving area Sb: pressure receiving area (effective area) of suction pressure acting in the expansion / contraction direction of the bellows
fs1: biasing force of the spring 309 fs2: biasing force of the spring 315 Fb: biasing force F (I) of the bellows assembly 303: electromagnetic force of the solenoid In the above formula (5), when Pd and F (I) are constant , Pc is a linear function of Ps, and Pc decreases as Ps increases, and conversely increases as Ps decreases, and its inclination is determined by (Sb + Sp−Sr) / (Sr−Sv). That is, the coefficient (Sb + Sp−Sr) / (Sr−Sv) of Ps is the sensitivity of Pc change to Ps change.
Since Sb, Sv, Sp, and Sr are the pressure receiving areas of the respective pressures, the sensitivity of the crank chamber pressure Pc when the suction pressure Ps changes can be adjusted by adjusting the pressure receiving areas.
Here, if (Sb + Sp−Sr) / (Sr−Sv) = 1, that is, Sb + Sp + Sv = 2Sr, the amount of change in the suction pressure Ps is equal to the amount of change in the crank chamber pressure Pc, and (Sb + Sp−Sr) / ( If Sr−Sv)> 1, the amount of change in the crank chamber pressure Pc with respect to the amount of change in the suction pressure Ps increases, and if (Sb + Sp−Sr) / (Sr−Sv) <1, the amount of change in the suction pressure Ps. The amount of change in the crank chamber pressure Pc with respect to is reduced. Therefore, if Sb, Sp, Sr, and Sv are set so as to satisfy (Sb + Sp−Sr) / (Sr−Sv)> 1, that is, Sb + Sp + Sv> 2Sr, the suction pressure Ps can be accurately controlled.
Thus, when Sr> Sv, the crank chamber pressure Pc acts in the direction of closing the valve body 304a, and as a result, as shown in [Equation 3], the sensitivity of the crank chamber pressure Pc when the suction pressure Ps changes is shown. Can be changed by appropriately adjusting Sb, Sp, Sr, and Sv, and the opening / closing state of the valve body 304a can be stabilized and the suction pressure control accuracy can be improved.
Further, in the capacity control valve 300, Sp is set slightly larger than Sv. For example, if the opening degree of the valve body 304a increases and the crank chamber pressure Pc increases, the discharge capacity decreases, but the discharge pressure Pd decreases as the discharge capacity decreases. If Sp> Sv is set so that the discharge pressure Pd acts in the valve opening direction, the force in the valve opening direction due to the discharge pressure Pd acting on the valve body 304a decreases when the discharge capacity decreases. There is an effect of suppressing excessive opening of the valve body 304a, which contributes to stabilization of the open / closed state of the valve body 304a.
In the above description, Pd and F (I) are constant, but when Pc is a linear function of Ps from the above equation (5), Pd and F (I) are only parameters, and Pd and F (I) are Even if it changes, the above description does not change.
In addition, if Formula (5) is modified, Formula (6) (the following [Equation 4]) is obtained. Expression (6) is a suction pressure control characteristic of the capacity control valve 300, and as shown in FIG. 6, the control suction pressure decreases as the current of the solenoid (electromagnetic coil) increases.

In each of the above embodiments, the inside of the bellows assembly is set to a vacuum pressure, but the inside of the bellows assembly may be atmospheric pressure. Further, a diaphragm may be used as the pressure sensitive member. The capacity control valve shown in FIG. 2 is a mechanical control valve, but may be an externally controlled capacity control valve in which a solenoid is added thereto to apply an electromagnetic force to the valve body. Further, although Sp> Sv is set in the capacity control valve shown in FIG. 5, Sp = Sv or Sp <Sv may be set.
Further, the present invention can be used for a variable displacement compressor driven by a swing plate type variable displacement compressor or a motor, and can be used for either a variable displacement compressor equipped with an electromagnetic clutch or a clutchless compressor. . Further, as the throttle element of the bleed passage, in addition to the above-mentioned orifice with a fixed opening, it is also possible to employ a variable flow rate throttle or a structure in which opening and closing is controlled by a valve body.
Furthermore, the present invention can also be applied to a variable capacity compressor that uses a new refrigerant (for example, a refrigerant that has been recently announced to prevent global warming) instead of the current R134a.

The present invention can be applied to any variable capacity compressor in which the stroke of the piston is adjusted by changing the pressure in the crank chamber by adjusting the opening of the capacity control valve, and particularly in a refrigeration circuit of a vehicle air conditioner. It is suitable for the variable capacity compressor provided.

Claims

A housing having a discharge chamber, a suction chamber, a crank chamber and a cylinder bore defined therein, a piston inserted into the cylinder bore, a drive shaft rotatably supported in the housing, and rotation of the drive shaft A motion conversion mechanism including a variable swash plate element that converts the piston into a reciprocating motion; a capacity control valve that opens and closes an air supply passage communicating the discharge chamber and the crank chamber; the crank chamber and the suction chamber; A throttle element disposed in a bleed passage communicating with the valve, and adjusting the stroke of the piston by changing the pressure of the crank chamber by adjusting the opening of the capacity control valve to reciprocate the piston. In the variable capacity compressor that sucks the refrigerant from the suction chamber into the cylinder bore and compresses the sucked refrigerant and discharges it to the discharge chamber.
The capacity control valve includes a valve chamber communicating with the discharge chamber, a valve hole having one end communicating with the valve chamber, and the other end communicating with the crank chamber, and facing the valve chamber and surrounding the valve hole. A valve seat that is disposed in the valve chamber, opens and closes the valve hole in contact with and away from the valve seat, a pressure sensing chamber that communicates with the suction chamber, and the pressure sensing A pressure-sensitive member disposed in the chamber and displaced in response to the pressure in the suction chamber; one end connected to the pressure-sensitive member; the other end connected to the valve body from the valve hole side; A pressure-sensitive rod that drives the valve body in response to displacement of the pressure member,
The pressure in the crank chamber is applied to the valve body from the valve hole side in the direction of opening the valve body, and the pressure of the crank chamber is applied to the pressure sensitive rod in the direction of closing the valve body from the valve hole side. In addition, when the pressure receiving area where the pressure sensing rod receives the pressure of the crank chamber is Sr and the pressure receiving area where the valve body receives the pressure of the crank chamber is Sv, Sr> Sv is satisfied. And Sv are set, the variable capacity compressor.
When the pressure of the discharge chamber acts on the valve body in the direction of closing the valve body, and the pressure receiving area where the pressure sensing member receives the pressure of the suction chamber is Sb, Sr + Sv> 2Sr is satisfied. , Sv and Sb are set, The variable capacity compressor according to claim 1.
The capacity control valve further includes a pressure chamber communicating with the suction chamber, one end of the valve body abuts and separates from the valve seat to open and close the valve hole, and the other end of the valve body is the pressure chamber The suction chamber is arranged so that the pressure of the suction chamber acts in the direction of closing the valve body, the pressure receiving area where the pressure-sensitive member receives the pressure of the suction chamber is Sb, and the valve body is the suction chamber 2. The variable capacity compressor according to claim 1, wherein Sr, Sv, Sp, and Sb are set so as to satisfy Sb + Sp + Sv> 2Sr, where Sp is the pressure-receiving area that receives the pressure of the chamber.
4. The variable capacity compressor according to claim 3, wherein Sp and Sv are set so as to satisfy Sp> Sv.
5. The variable capacity compressor according to claim 1, wherein the throttle element disposed in the extraction passage is an orifice having a fixed opening.
The variable capacity compressor according to any one of claims 1 to 5, comprising a compressor provided in a refrigeration circuit of a vehicle air conditioner.