Patent Publication Number: US-6659742-B2

Title: Directional flow valve structure for reciprocating compressors

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to reciprocating compressors for use in an air conditioning system of a vehicle. More particularly, the invention relates to reciprocating compressors having an improved refrigerant suction efficiency. 
     2. Description of Related Art 
     Reciprocating compressors may include swash plate-type compressors, wobble plate-type compressors, or the like. Referring to FIG. 1, a known, wobble plate-type compressor  100  is described. Compressor  100  may comprise a cylinder block  1 , a front housing  2 , a rear housing  3 , and a drive shaft  7 . Drive shaft  7  may pass through the center of front housing  2  and the center of cylinder block  1 . Drive shaft  7  also may be rotatably supported by front housing  2  and by cylinder block  1  via a pair of bearings  8   a  and  8   b  mounted in front housing  2  and cylinder block  1 , respectively. A plurality of cylinder bores  5  may be formed within cylinder block  1  and also may be positioned equiangularly around an axis of drive shaft  7 . Moreover, a piston  16  may be slidably positioned within each cylinder bore  5 , such that pistons  16  reciprocate in a direction parallel to the axis of drive shaft  7 . 
     Compressor  100  also may comprise a driving mechanism (not numbered). The driving mechanism may comprise drive shaft  7 , a rotor  9 , a crank chamber  4 , and a swash plate  6 . Specifically, rotor  9  is fixed to drive shaft  7 , such that drive shaft  7  and rotor  9  rotate together. Crank chamber  4  is formed between front housing  2  and cylinder block  1 , and swash plate  6  may be positioned inside crank chamber  4 . Swash plate  6  may include a penetration hole  6   c  formed therethrough at a center portion of swash plate  6 , and drive shaft  7  may extend through penetration hole  6   c.  Moreover, rotor  9  and swash plate  6  may be connected by a hinge mechanism  11  comprising a pin (not numbered) and an oblong hole (not numbered) formed through hinge mechanism  11 . Hinge mechanism  11  allows the tilt angle of swash plate  6  to vary with respect to drive shaft  7 . The drive mechanism also may comprise a substantially ring-shaped wobble plate  14  and a connection rod  15 , and compressor  100  further may comprise a rotation prevention mechanism  17 . Wobble plate  14  may be rotatably attached to swash plate  6  by a thrust bearing  12  and a radial bearing  13 , and may engage rotation prevention mechanism  17 . Wobble plate  14  also may be connected to piston  16  by rod  15  and a pair of ball joints  15   a  and  15   b.  Moreover, rotation prevention mechanism  17  may prevent wobble plate  14  from rotating about the axis of drive shaft  7 . Nevertheless, ball joints  15   a  and  15   b  may allow wobble plate  14  to move back and forth in a wobbling motion. 
     Referring to FIGS. 1-3, compressor  100  also may comprise a valve plate  20  positioned between cylinder block  1  and rear housing  3 , and a suction chamber  18  formed between rear housing  3  and valve plate  20 . Valve plate  20  may include a suction hole  20   a  formed therethrough, which may allow suction chamber  18  to be in fluid communication with cylinder bore  5 , such that a fluid, e.g., a refrigerant introduced from an external refrigerant circuit (not shown), may flow from suction chamber  18  to cylinder bore  5 . Valve plate  20  may comprise a suction valve reed  21  formed on a side, e.g., the left side, of valve plate  20 . Suction valve reed  21  regulates the fluid communication between suction chamber  18  and cylinder bore  5 . Moreover, a limiting recess  23 ′ formed in cylinder block  1  and having a bottom surface  23   b  may limit the extent to which suction valve reed  21  may bend when fluid flows from suction chamber  18  to cylinder bore  5 . Limiting recess  23 ′ comprises an arced segment formed symmetrically about a center axis (X) of suction valve reed  21 , such that axis (X) also is the center axis of limiting recess  23 ′. 
     Compressor  100  further may comprise a discharge chamber  19 , and valve plate  20  further may include a discharge hole  20   b  formed therethrough. Discharge hole  20   b  may allow cylinder bore  5  to be in fluid communication with discharge chamber  19 , such that a fluid, e.g., a refrigerant, may flow from cylinder bore  5  to discharge chamber  19 . The refrigerant subsequently may be discharged from discharge chamber  19  to the external refrigerant circuit. Valve plate  20  also may comprise a discharge valve reed  22  formed on a side, e.g., the right side, of valve plate  20 . Specifically, discharge valve reed  22  is formed on the side opposite the side which suction valve reed  21  is formed. Discharge valve reed  22  regulates the fluid communication between cylinder bore  5  and discharge chamber  19 . Moreover, a valve retainer  30  formed on discharge valve reed  22  may limit the extent to which discharge valve reed  22  may bend when fluid flows from cylinder bore  5  to discharge chamber  19 . 
     Compressor  100  also may comprise an electromagnetic clutch  24 . When electromagnetic clutch  24  is activated, an external driving force from an external driving source (not shown) is transmitted to drive shaft  7 , such that drive shaft  7 , rotor  9 , and swash plate  6  rotate substantially simultaneously about the axis of drive shaft  7 . Moreover, wobble plate  14  moves back and forth in a wobbling motion without rotating about the axis of drive shaft  7 , such that only a direction of movement which is parallel to the axis of drive shaft  7  is transferred from wobble plate  14  to pistons  16 . Consequently, each piston  16  reciprocates within its corresponding cylinder bore  5  and compresses the fluid, e.g., the refrigerant, which flows into cylinder bore  5  from suction chamber  18  via suction hole  20   a.    
     The reciprocation of piston  16  may be divided into a suction stroke and a discharge stroke. Specifically, during the suction stroke, discharge hole  20   b  may be closed by discharge valve reed  22 , and during the discharge stroke, suction hole  20   a  may be closed by suction valve reed  21 . Referring to FIGS. 2 and 3, during the suction stroke, the fluid generally flows in the direction of limiting recess  23 ′ as indicated by the arrow (L 1 ). When the fluid approaches or reaches limiting recess  23 ′, the fluid deflects off a portion of limiting recess  23 ′ which intersects with center axis (X) and has a tangent line at the point of intersection which is substantially perpendicular to center axis (X) of suction valve reed  21 . As such, when the fluid approaches or reaches limiting recess  23 ′, the direction of the flowing fluid changes by about 90° and the fluid flows in the directions indicated by the arrow (L 2 ). Nevertheless, because the direction of the flowing fluid changes by about 90° when the fluid approaches or reaches limiting recess  23 ′, the speed of the fluid decreases and the fluid may become stagnant within limiting recess  23 ′. Consequently, during the suction stroke, the suction efficiency of the compressor may decrease. 
     SUMMARY OF THE INVENTION 
     Therefore, a need has arisen for refrigerant compressor which overcomes these and other shortcomings of the related art. A technical advantage of the present invention is that during the suction stroke, when a fluid approaches or reaches a limiting recess, the fluid may not become stagnant. Specifically, when the fluid approaches or reaches the limiting recess, the fluid may contact a portion of the limiting recess having a tangent line which forms an oblique angle relative to a center axis of a suction valve reed, i.e., an axis which is parallel to the direction of fluid flow. Consequently, when the fluid approaches or reaches the limiting recess, the fluid may deflect at an angle less than 90°, and the suction efficiency of the compressor may increase. 
     According to an embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. The limiting recess comprises at least one arced segment intersecting a center axis of the suction valve reed. Moreover, the portion of the at least one arced segment which intersects the center axis of the suction valve reed has a corresponding tangential line at the point of intersection which forms an oblique angle relative to the center axis of the suction valve reed. 
     According to another embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. Moreover, the limiting recess comprises a pair of arcs intersecting at or intersecting proximate to a center axis of the suction valve reed to form a ridge extending towards a center axis of the cylinder bore. 
     According to another embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. Moreover, the limiting recess comprises a pair of arcs intersecting at an axis offset from a center axis of the suction valve reed to form a ridge extending towards a center axis of the cylinder bore. 
     Other objects, features, and advantages will be apparent to persons of ordinary skill in the art in view of the following detailed description of the invention and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, the needs satisfied thereby, and the features and advantages thereof, reference now is made to the following descriptions taken in connection with the accompanying drawings. 
     FIG. 1 is a cross-sectional view of a known, wobble plate-type compressor. 
     FIG. 2 is an enlarged, plan view of a valve plate and a limiting recess of a known compressor. 
     FIG. 3 is an enlarged, cross-sectional view of a cylinder bore of a known compressor. 
     FIG. 4 is a cross-sectional view of a wobble plate-type compressor according to a first embodiment of the present invention. 
     FIG. 5 is an enlarged, plan view of a valve plate and a limiting recess according to the first embodiment of the present invention. 
     FIG. 6 is an enlarged, plan view of a valve plate and a limiting recess according to a second embodiment of the present invention. 
     FIG. 7 is an enlarged, plan view of a valve plate and a limiting recess according to a third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention and their advantages may be more readily understood by referring to FIGS. 4-7, like numerals being used for like corresponding parts in the various drawings. 
     Referring to FIG. 4, a refrigerant compressor  200  according to a first embodiment of the present invention is described. Although FIG. 4 depicts a wobble plate-type compressor, it will be understood by those of ordinary skill in the art that refrigerant compressors include wobble plate-type compressors, swash-plate type compressors, or the like, and that the present invention may be used in various types of refrigerant compressor, e.g., reciprocating compressors. Compressor  200  may comprise a cylinder block  1 , a front housing  2 , a rear housing  3 , and a drive shaft  7 . Drive shaft  7  may pass through the center of front housing  2  and the center of cylinder block  1 . Drive shaft  7  may be rotatably supported by front housing  2  and by cylinder block  1  via a pair of bearings  8   a  and  8   b , respectively. A plurality of cylinder bores  5  may be formed within cylinder block  1  and may be positioned equiangularly around an axis of drive shaft  7 . Moreover, a plurality of pistons  16  may be slidably positioned within cylinder bores  5 , such that pistons  16  reciprocate in a direction parallel to the axis of drive shaft  7 . 
     Compressor  200  also comprises a drive mechanism (not numbered). The drive mechanism may comprise drive shaft  7 , a rotor  9 , a crank chamber  4 , and a swash plate  6 . Specifically, rotor  9  may be fixed to drive shaft  7 , such that drive shaft  7  and rotor  9  rotate together. Crank chamber  4  is formed between front housing  2  and cylinder block  1 , and swash plate  6  may be positioned inside crank chamber  4 . Swash plate  6  may include a penetration hole  6   c  formed therethrough at a center portion of swash plate  6 , and drive shaft  7  may extend through penetration hole  6   c.  Moreover, rotor  9  and swash plate  6  may be connected by a hinge mechanism  11  comprising a pin (not numbered) and an oblong hole (not numbered) formed through hinge mechanism  11 . Hinge mechanism  11  allows the tilt angle of swash plate  6  to vary with respect to drive shaft  7 . The drive mechanism also may comprise a substantially ring-shaped wobble plate  14  and a connection rod  15 , and compressor  200  further may comprise a rotation prevention mechanism  17 . Wobble plate  14  may be rotatably attached to swash plate  6  by a thrust bearing  12  and a radial bearing  13 , and may engage rotation prevention mechanism  17 . Wobble plate  14  also may be connected to piston  16  by rod  15  and a pair of ball joints  15   a  and  15   b.  Moreover, rotation prevention mechanism  17  may prevent wobble plate  14  from rotating about the axis of drive shaft  7 . Nevertheless, ball joints  15   a  and  15   b  may allow wobble plate  14  to move in a back and forth wobbling motion. 
     Compressor  200  also may comprise a valve plate  20  positioned between cylinder block  1  and rear housing  3 , and a suction chamber  18  formed between rear housing  3  and valve plate  20 . Valve plate  20  may include a suction hole  20   a  formed therethrough, which allows suction chamber  18  to be in fluid communication with cylinder bore  5 , such that a fluid, e.g., a refrigerant introduced from an external refrigerant circuit (not shown), may flow from suction chamber  18  to cylinder bore  5 . Valve plate  20  may comprise a suction valve reed  21  formed on a side, e.g., the left side, of valve plate  20 . Suction valve reed  21  regulates the fluid communication between suction chamber  18  and cylinder bore  5 . Moreover, a limiting recess  23  formed in cylinder block  1  and having a bottom surface  23   b  may limit the extent to which suction valve reed  21  may bend when fluid flows from suction chamber  18  to cylinder bore  5 . 
     Compressor  200  further may comprise a discharge chamber  19 , and valve plate  20  further may include a discharge hole  20   b  formed therethrough. Discharge  20   b  may allow cylinder bore  5  to be in fluid communication with discharge chamber  19 , such that a fluid, e.g., a refrigerant, may flow from cylinder bore  5  to discharge chamber  19 . The refrigerant subsequently may be discharged from discharge chamber  19  to the external refrigerant circuit. Valve plate  20  also may comprise a discharge valve reed  22  formed on a side, e.g., the right side, of valve plate  20 . Specifically, discharge valve reed  22  is formed on the side opposite the side which suction valve reed  21  is formed. Discharge valve reed  22  regulates the fluid communication between cylinder bore  5  and discharge chamber  19 . Moreover, a valve retainer  30  formed on discharge valve reed  22  may limit the extent to which discharge valve reed  22  may bend when fluid flows from cylinder bore  5  to discharge chamber  19 . 
     Compressor  200  also may comprise an electromagnetic clutch  24 . When electromagnetic clutch  24  is activated, an external driving force from an external driving source (not shown) is transmitted to drive shaft  7 , such that drive shaft  7 , rotor  9 , and swash plate  6  substantially simultaneously rotate about the axis of drive shaft  7 . Moreover, wobble plate  14  moves back and forth in a wobbling motion without rotating about the axis of drive shaft  7 , such that a direction of movement which is parallel to the axis of drive shaft  7  is transferred from wobble plate  14  to pistons  16 . Consequently, each piston  16  reciprocates within its corresponding cylinder bore  5  and compresses the fluid, e.g., the refrigerant, which flows into cylinder bore  5  from suction chamber  18  via suction hole  20   a.    
     Referring to FIG. 5, limiting recess  23  according to the first embodiment of the present invention is described in detail. In this embodiment, limiting recess  23  may comprise a pair of arced segments having curved walls  23   e  and  23   f,  respectively, which intersect at or intersect proximate to a center axis (X) of suction valve reed  21 , such that limiting recess  23  is substantially symmetrical about center axis (X). In a modification of this embodiment, the portion of wall  23   e  or wall  23   f , or both, which intersects with a circumferential portion 5 w of cylindrical bore  5 , may be chamfered. Moreover, a center axis of each of the arced segments may be offset from center axis (X), such that the intersection of walls  23   e  and  23   f  at or proximate to center axis (X) forms a ridge  23   a  extending towards a center axis (Z) of cylinder bore  5 . Specifically, ridge  23   a  is formed, such that walls  23   e  and  23   f  extend further away from center axis (Z) than ridge  23   a,  i.e. are further recessed than ridge  23   a.  Further, the point of intersection between walls  23   e  and  23   f,  i.e. ridge  23   a,  has a tangent line which forms an oblique angle relative to center axis (X). 
     During a suction stroke, the fluid, e.g., the refrigerant, generally flows in the direction of limiting recess  23  as indicated by the arrow (L 1 ). When the fluid approaches or reaches limiting recess  23 , the fluid divides and generally flows in the directions indicated by the arrow (L 3 ). Nevertheless, because walls  23   e  and  23   f  extend further away from center axis (Z) than ridge  23   a,  the fluid initially deflects off ridge  23   a  and subsequently flows along walls  23   e  and  23   f.  Moreover, because the fluid initially deflects off ridge  23   a,  which is formed by the intersection of walls  23   e  and  23   f  at or proximate to center axis (X) and has a tangent line at the point of intersection which forms an oblique, i.e., slanting, angle relative to center axis (X), the angle of deflection of the fluid when the fluid approaches or reaches limiting recess  23  is less than 90°. Consequently, during the suction stroke, when the fluid approaches or reaches limiting recess  23 , the fluid may not become stagnant, and the suction efficiency of compressor  200  may increase. 
     Referring to FIG. 6, limiting recess  23  according to a second embodiment of the present invention is described. The features and advantages of this embodiment are substantially similar to those of the first embodiment. Therefore, the features and advantages of the first embodiment are not described further with respect to the second embodiment. In this embodiment, limiting recess  23  may comprise a pair of arced segments having curved walls  23   e  and  23   f , respectively, intersecting at or intersecting proximate to a center axis (X) of suction valve reed  21 , such that limiting recess  23  is substantially symmetrical about center axis (X). In a modification of this embodiment, the portion of wall  23   e  or wall  23   f , or both, which intersects with a circumferential portion  5   w  of cylindrical bore  5 , may be chamfered. Moreover, a center axis of each of the arced segments may be offset from center axis (X) such that an intersection of walls  23   e  and  23   f  at or proximate to center axis (X) may forms a ridge  23   a  extending towards a center axis (Z) of cylinder bore  5 . Specifically, ridge  23   a  is formed such that walls  23   e  and  23   f  extend further away from center axis (Z) than ridge  23   a , and ridge  23   a  extends into or is proximate to circumferential portion  5   w  of cylindrical bore  5 . Further, the point of intersection between walls  23   e  and  23   f , i.e., ridge  23   a , has a tangent line which forms an oblique angle relative to center axis (X). Moreover, a notch  21   b  adapted to receive, but not touch ridge  23   a  may be formed in a tip  21   a  of suction valve reed  21 . 
     Referring to FIG. 7, a limiting recess  25  according to a third embodiment of the present invention is described. The features and advantages of this embodiment are substantially similar to those of the foregoing embodiments. Therefore, the features and advantages of the foregoing embodiments are not described further with respect to the third embodiment. In this embodiment, limiting recess  25  may comprise a pair of arced segments having curved walls  25   a  and  25   b,  respectively, intersecting at an axis (Y) offset from center axis (X) of suction valve reed  21 , such that limiting recess  25  is symmetrical about axis (Y). In a modification of this embodiment, the portion of wall  25   a  which intersects with a circumferential portion 5 w of cylindrical bore  5  may be chamfered. Moreover, a center axis of each of the arced segments may be offset from axis (Y) such that an intersection of walls  25   a  and  25   b  at axis (Y) may form a ridge  25   d  extending towards a center axis (Z) of cylinder bore  5 . Moreover, a tip  21   c  of suction valve reed  21  may extend into limiting recess  25 , such that tip  21   c  is proximate to, e.g., almost touches, at least a portion of crescent-shaped wall  25   b.    
     During a suction stroke, the fluid, e.g., the refrigerant, generally flows in the direction parallel to center axis (X), as indicated by the arrow (L 1 ). When the fluid approaches or reaches limiting recess  25 , the fluid generally is deflected towards ridge  25   d  and wall  25   a  by a portion of wall  25   b  which intersects center axis (X), as indicated by the arrow (L 5 ). Nevertheless, because the fluid deflects off a portion of limiting recess  25  intersecting center axis (X) and having a tangent line at that point of intersection which forms an oblique, i.e., slanting, angle relative to center axis (X), the angle of deflection of the fluid when the fluid approaches or reaches limiting recess  25  is less than 90°. Consequently, during the suction stroke, when the fluid approaches or reaches limiting recess  25 , the fluid may not become stagnant and the suction efficiency of compressor  200  may increase. 
     While the invention has been described in connection with preferred embodiments, it will be understood by those skilled in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those skilled in the art from a consideration of the specification or practice of the invention disclosed herein. It is intended that the specification and the described examples are considered as exemplary.