| Control device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressor -> Monitor Keywords |
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Control device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressorRelated Patent Categories: Pumps, Condition Responsive Control Of Drive Transmission Or Pump Displacement, Adjustable Cam Or Linkage, Axial Cam, With Sump Pressure ActuationControl device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070116578, Control device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to a control device for a vehicular refrigeration circuit, a variable displacement compressor, and a control valve for the variable displacement compressor. BACKGROUND OF THE INVENTION [0002] JP 03-43685 A discloses a conventional variable displacement compressor. The variable displacement compressor includes a crank chamber, an intake chamber, and a discharge chamber, in which discharge capacity can be changed by controlling pressure of the crank chamber. [0003] In the variable displacement compressor, the intake chamber is connected to an evaporator through tubing, the evaporator is connected to an expansion valve through the tubing, the expansion valve is connected to a condenser through the tubing, and the condenser is connected to the discharge chamber of the variable displacement compressor. With this construction, the variable displacement compressor may be used together with an exterior refrigerant circulation circuit composed of the evaporator, the expansion valve, the condenser, and the tubing, and may constitute a refrigeration circuit for a vehicle or the like. [0004] In the variable displacement compressor, the intake chamber and the crank chamber communicate with each other through a bleed passage, and the discharge chamber and the crank chamber communicate with each other through an air supply passage. Further, the variable displacement compressor includes a first control device and a second control device built therein. The first control device and the second control device are control devices used for the refrigeration circuit which is used together with the variable displacement compressor and the exterior refrigerant circulation circuit. [0005] The first control device includes a primary valve mechanism capable of changing a primary opening which is the degree of opening of the bleed passage, and a bellows provided in the bleed passage. The bellows moves in an axial direction while causing a first load due to the pressure of the crank chamber. The primary opening of the bleed passage decreases when the pressure of the crank chamber is higher than a set pressure and increases when the pressure of the crank chamber is lower than the set pressure. [0006] Further, the first control device includes an intermediate chamber communicating with the discharge chamber through a fixed restriction and an actuating rod extending from the discharge chamber through the intermediate chamber to a valve body of the primary valve mechanism. The actuating rod has a small diameter portion on the discharge chamber side and a large diameter portion on the primary valve mechanism side, the large diameter portion being larger in diameter than the small diameter portion. An end of the small diameter portion of the actuating rod is exposed to the discharge chamber and a middle portion thereof faces the intermediate chamber. The discharge chamber and the intermediate chamber communicate with each other through the fixed restriction formed of a gap between the actuating rod and an axial hole of a valve cylinder for accommodating the actuating rod. Further, provision of the axial hole enables the intermediate chamber to allow pressure to act on the large diameter portion of the actuating rod. Thus, the actuating rod moves in the axial direction while causing a second load opposing the first load with the pressure of the discharge chamber and the pressure of the intermediate chamber, and adjust the primary valve mechanism so that the primary opening decreases or increases. [0007] The second control device includes an electromagnetic flow control valve capable of varying the pressure of the intermediate chamber. The electromagnetic flow control valve is provided in a communication passage for allowing the intermediate chamber and the intake chamber to communicate with each other. The electromagnetic flow control valve can change a secondary opening, that is, the degree of opening of the communicating passage, due to an energization control from the outside, thereby changing the pressure of the intermediate chamber. [0008] In the refrigeration circuit structured as described above, since the pressure of the crank chamber is a pressure with a factor for controlling the discharge capacity, the bellows of the first control device appropriately moves due to the pressure of the crank chamber, and the primary valve mechanism changes the primary opening of the bleed passage. As a result, this determines the pressure of the crank chamber primarily. [0009] Further, the second control device changes the pressure of the intermediate chamber through the energization control. The actuating rod of the second control device appropriately moves due to the pressure of the discharge chamber and the pressure of the intermediate chamber. Thus, the actuating rod adjusts the primary valve mechanism so that the primary opening of the bleed passage decreases or increases. As a result, the pressure of the crank chamber is determined secondarily. [0010] In this manner, the discharge capacity of the variable displacement compressor is changed. This refrigeration circuit is aimed at obtaining precise air conditioning according to the driving state of the variable displacement compressor, the outside environment, and the like. [0011] However, the above-mentioned refrigeration circuit allows the pressure of the discharge chamber to act on the actuating rod as it is. The pressure of the discharge chamber naturally fluctuates according to the driving state of the variable displacement compressor, the outside environment, or the like. Therefore, in this refrigeration circuit, the actuating rod can resist the first load of the bellows too much or not resist it enough, so the pressure of the crank chamber may not be maintained in an optimum state. [0012] The refrigeration circuit also allows the pressure of the intermediate chamber to act on the actuating rod and allows the pressure of the intermediate chamber to be changed through energization control from the outside by the electromagnetic flow control valve. Thus, it is felt that this refrigeration circuit is aimed at solving malfunctions due to fluctuations in the pressure of the discharge chamber by the energization control. [0013] However, in this refrigeration circuit, when an attempt is made to solve malfunctions due to fluctuations of the pressure of the discharge chamber, the energization control must be performed in response to unsteady discharge pressure, so control by using a controller becomes complicated. In particular, in this refrigeration circuit, the pressure of the intermediate chamber itself, which is changed by the energization control, is affected by the pressure of the discharge chamber to fluctuate, so control by using the controller becomes more complicated. [0014] Thus, this refrigerator circuit involves considerable difficulties in truly performing precise air conditioning according to a driving state of the variable displacement compressor, the outside environment, and the like. SUMMARY OF THE INVENTION [0015] The present invention has been made in view of the above-mentioned conventional problems. An object to be solved by the present invention is therefore the relatively easy realization of precise air conditioning according to the driving state of the variable displacement compressor, the outside environment, and the like. [0016] According to the present invention, a control device for a vehicular refrigeration circuit is used together with a variable displacement compressor, having a crank chamber, an intake chamber and a discharge chamber, in which discharge capacity can be changed by controlling a pressure of the crank chamber, and with an exterior refrigerant circulation circuit connected to the intake chamber and the discharge chamber of the variable displacement compressor. [0017] The control device is characterized by including: a bleed passage for communicating the intake chamber and the crank chamber with each other; an air supply passage for communicating the discharge chamber and the crank chamber with each other; a primary valve mechanism capable of changing a primary opening which is the degree of opening of at least one of the bleed passage and the air supply passage; a first pressure sensing member which moves while causing a first load due to a state pressure which is a pressure having a factor for controlling the discharge capacity and operates the primary valve mechanism so that the primary opening increases or decreases; a constant pressure valve mechanism for maintaining a high pressure in a high pressure chamber communicated with the discharge chamber, at a constant correction pressure; a secondary valve mechanism capable of changing the correction pressure to a predetermined control pressure by external energization control; and a second pressure sensing member which moves while causing a second load opposing the first load with the control pressure to correct the primary opening. [0018] The primary valve mechanism may also be capable of changing the primary opening which is the degree of opening of the bleed passage, of changing the primary opening which is the degree of opening of the air supply passage, or of changing the primary opening which is the degree of opening of both the bleed passage and the air supply passage. [0019] The first pressure sensing member moves due to a state pressure. The state pressure is a pressure having a factor for controlling the discharge capacity. As the state pressure, it is possible to adopt the intake pressure, for example, inside the intake chamber or in a low pressure portion of the exterior refrigerant circulation circuit, the discharge pressure, for example, of the discharge chamber or in a high pressure portion the exterior refrigerant circulation circuit, the differential pressure between the discharge pressures, or the like. As the first pressure sensing member, it is possible to adopt a bellows, a diaphragm, a rod, or the like. [0020] As the constant pressure valve mechanism, a pressure regulating valve of a known constant pressure valve (i.e., pressure reducing valve) or the like may be adopted. Note that, the high pressure chamber may be directly connected to the discharge chamber or may be indirectly connected to the discharge chamber so as to be directly connected to the high pressure portion of the exterior refrigerant circulation circuit or the like. [0021] As the secondary valve mechanism, it is possible to adopt a piezoelectric element, an electromagnetic opening/closing valve, or the like. Continue reading about Control device for a vehicular refrigeration, vehicular variable displacement compressor, and a control valve for the vehicular variable displacement compressor... 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