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Displacement control valve for variable displacement compressorRelated Patent Categories: Pumps, Condition Responsive Control Of Drive Transmission Or Pump Displacement, Adjustable Cam Or Linkage, Axial Cam, With Sump Pressure ActuationDisplacement control valve for variable displacement compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060165534, Displacement control valve for variable displacement compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a displacement control valve used for a variable displacement compressor that adjusts the pressure in a pressure control chamber by introducing refrigerant in the discharge pressure region of the compressor into the pressure control chamber through a supply passage and releasing the refrigerant in the pressure control chamber to the suction pressure region of the compressor through a bleed passage, thereby to control displacement of the compressor. [0002] In a variable displacement compressor having a pressure control chamber that accommodates therein a swash plate whose inclination angle is variable, the inclination angle of the swash plate decreases as the pressure in the pressure control chamber rises. This decrease of the inclination angle increases the stroke of a piston thereby to increase the displacement of the compressor. On the other hand, the inclination angle of the swash plate increases as the pressure in the pressure control chamber falls. This increase of the inclination angle decreases the stroke of the piston thereby to decrease the displacement of the compressor. [0003] Unexamined Japanese Patent Publication No. 2001-349278 discloses a displacement control valve having a valve body which is operable to open and close a supply passage through which a refrigerant gas in the discharge pressure region of the compressor is introduced into a crank chamber (or pressure control chamber). The valve body has a tapered portion which is movable to be brought into contact with a valve seat thereby to close a valve hole. When the valve body is moved or shifted in the direction that opens the valve hole, the amount of the refrigerant flowing from the discharge pressure chamber to the crank chamber increases. Thus, the pressure in the crank chamber rises, thereby decreasing the displacement of the compressor. On the other hand, when the valve body is shifted in the direction that closes the valve hole, the amount of the refrigerant flowing from the discharge pressure chamber to the crank chamber decreases. Thus, the pressure in the crank chamber falls, thereby increasing the displacement of the compressor. [0004] When the valve body of the above displacement control valve is shifted in the direction for closing the valve hole, the tapered portion of the valve body is moved with the minimum-diameter portion thereof entering into the valve hole, until the tapered portion of the valve body is brought into contact at any intermediate-diameter portion thereof with the valve seat or the edge of opening of the valve hole. Since the maximum-diameter portion of the tapered portion of the valve body is larger than the inner diameter of the valve hole, the movement of the valve body is stopped before the maximum-diameter portion of the tapered portion reaches the valve seat. When the valve hole is opened, the refrigerant gas in the discharge pressure region flows past the tapered portion of the valve body in the direction from the minimum diameter portion to the maximum diameter portion. Thus, the tapered portion of the valve body is subjected to a pressure which is substantially the same as the discharge pressure of the compressor and acts on the valve body in the direction which causes an increase of the opening of the valve hole. On the other hand, the pressure in the crank chamber (or control pressure) acts on the valve body in the direction opposite to the above pressure. [0005] The pressure of refrigerant gas present adjacent to the part of the valve body which protrudes radially outward beyond the inner peripheral surface of the valve hole as seen in the moving direction (or the axial direction) of the valve body, or whose diameter is greater than the inner diameter of the valve hole, is varied depending on the opening degree of the valve hole when the valve hole is opened. Namely, the pressure acting on the above protruding part of the tapered portion is varied according to the opening degree of the valve hole. Such pressure varying with the valve opening will affect the difference of pressures acting on the valve body in opposing directions and hence the accuracy of displacement controlling of the compressor. [0006] The present invention is directed to a displacement control valve that contributes to improvement in controllability of the displacement of a variable displacement compressor. SUMMARY OF THE INVENTION [0007] According to the present invention, a displacement control valve is used for a variable displacement compressor that adjusts a pressure in a pressure control chamber by introducing a refrigerant in a discharge pressure region into the pressure control chamber through a supply passage and releasing the refrigerant in the pressure control chamber to a suction pressure region through a bleed passage, thereby controlling displacement of the compressor. The displacement control valve includes a valve hole and a valve body. The valve hole partially forms the supply passage or the bleed passage. The valve body has a cross-sectional area changed portion that is movable into and out of the valve hole. The cross-sectional area changed portion has a minimum cross-sectional area portion and a maximum cross-sectional area portion. The cross-sectional area changed portion is shaped so that a cross-sectional area of the cross-sectional area changed portion increases from the minimum cross-sectional area portion to the maximum cross-sectional area portion. The minimum cross-sectional area portion initially enters into the valve hole when the cross-sectional area changed portion is moved into the valve hole. The maximum cross-sectional area portion is movable into the valve hole. The valve hole is closed when the maximum cross-sectional area portion is positioned in the valve hole. BRIEF DESCRIPTION OF THE DRAWINGS [0008] The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: [0009] FIG. 1A is a longitudinal cross-sectional view of a compressor of a first preferred embodiment according to the present invention; [0010] FIG. 1B is a cross-sectional view of a hinge mechanism of the compressor of the first preferred embodiment; [0011] FIG. 2A is a cross-sectional view of a displacement control valve of the first preferred embodiment; [0012] FIG. 2B is a partially enlarged cross-sectional view of the displacement control valve of the first preferred embodiment when a valve hole is blocked; [0013] FIG. 3 is a partially enlarged cross-sectional view of the displacement control valve of the first preferred embodiment when the valve hole is opened; [0014] FIG. 4 is a partially enlarged cross-sectional view of the displacement control valve of the first preferred embodiment when the valve hole is fully opened; [0015] FIG. 5 is a cross-sectional view of a displacement control valve of a second preferred embodiment according to the present invention; [0016] FIG. 6 is a cross-sectional view of a displacement control valve of a third preferred embodiment according to the present invention; and [0017] FIG. 7 is a cross-sectional view of a displacement control valve of a fourth preferred embodiment according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0018] The following will describe a first preferred embodiment according to the present invention with reference to FIGS. 1A through 4. Referring to FIG. 1A, a variable displacement compressor 10 has a housing assembly which includes a cylinder block 11, a front housing 12 and a rear housing 13. The front housing 12 is connected to the front end (the left end as seen in FIG. 1) of the cylinder block 11. The rear housing 13 is connected to the rear end (the right end as seen in FIG. 1) of the cylinder block 11 through a valve plate 14, valve plate forming plates 15 and 16 and a retainer forming plate 17. [0019] The front housing 12 and the cylinder block 11 cooperate to define therein a pressure control chamber 121 through which a rotary shaft 18 extends. The rotary shaft 18 is supported by the front housing 12 and the cylinder block 11 via radial bearings 19 and 20. The rotary shaft 18 extends out of the front housing 12 and is driven to rotate by a vehicle engine E as an external drive source via an electromagnetic clutch (not shown). [0020] A lug plate 21 is secured to the rotary shaft 18. A swash plate 22 is supported by the rotary shaft 18 in such a way that it is slidable in the axial direction of the rotary shaft 18 and inclinable relative to the axis of the rotary shaft 18. A hinge mechanism 23 is provided between the swash plate 22 and the lug plate 21 for allowing the swash plate 22 to incline relative to the lug plate 21 and transmitting the rotation of the rotary shaft 18 to the swash plate 22. As shown in FIG. 1B, the hinge mechanism 23 includes a pair of arms 212 and 213 extending from the lug plate 21 toward the swash plate 22 and a pair of projections 221 and 222 extending from the swash plate 22 toward the lug plate 21. The projections 221 and 222 are inserted in a recess 214 formed between the paired arms 212 and 213 and movable in the recess 214. The bottom of the recess 214 provides a cam surface 211 on which the ends of the projections 221 and 222 are slidable. The above-described arrangement of the paired arms 212 and 213, the paired projections 221 and 222 and the cam surface 211 permits the swash plate 22 to incline relative to the axis of the rotary shaft 18 and also to rotate with the rotary shaft 18. The inclination of the swash plate 22 is guided with the projections 221 and 222 sliding on the cam surface 211 and the swash plate 22 sliding on the rotary shaft 18. Continue reading about Displacement control valve for variable displacement compressor... Full patent description for Displacement control valve for variable displacement compressor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Displacement control valve for variable displacement compressor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Displacement control valve for variable displacement compressor or other areas of interest. ### Previous Patent Application: Method and device for recycling gas Next Patent Application: Swash plate type compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Displacement control valve for variable displacement compressor patent info. 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