Patent Publication Number: US-6712589-B2

Title: Scroll compressors

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to scroll compressors, and in particular to scroll compressors known as “double rotational compressors,” in which a drive scroll rotates in synchronism with a driven scroll about respective rotational axes that are offset to each other. 
     2. Description of Related Art 
     Japanese Laid-open Patent Publication No. 7-229480 discloses a double rotational scroll compressor, in which a drive scroll and a driven scroll oppose each other and define a compression chamber therebetween. The drive scroll is secured to a rotor of an electric motor, and the rotor and the drive scroll are rotatably and coaxially supported within a housing. The driven scroll is rotatably supported by an eccentric mechanism that is mounted on a shaft and the shaft extends though the rotor. An Oldham&#39;s coupling serves to transmit the rotation of the rotor or the drive scroll to the driven scroll. 
     In such a scroll compressor, the rotor and the drive scroll secured to the rotor oppose each other and the driven scroll is interposed therebetween. Further, respective support shafts must support the rotor and the drive scroll. Therefore, the drive scroll is actually supported by support shafts disposed on both sides. In other words, the support shafts mounted within the housing must rotatably support the rotor of the electric motor. As a result, the length of the compressor along the axial direction of the rotor is relatively long. In addition, because the driven scroll is mounted on the support shaft (which supports the rotor) by means of the eccentric mechanism, the number of parts and the manufacturing costs of the compressor are relatively high. 
     SUMMARY OF THE INVENTION 
     Therefore, one object of the present teachings is to provide improved scroll compressors that preferably are more compact than known scroll compressors. Such scroll compressors may, e.g., find advantageous application in vehicle air conditioning systems. 
     In one aspect of the present teachings, scroll compressors are taught that have a drive scroll opposing a driven scroll. One or more compression chambers may be defined between the drive scroll and the driven scroll. One or both of the drive scroll and the driven scroll may be supported in a cantilever manner. Therefore, it is possible to eliminate a rotor support mechanism (a shaft and a bearing) as compared to known scroll compressors. Further, the length of the compressor along the axial direction of the scrolls can be reduced as compared to known scroll compressors. Therefore, scroll compressors according to the present teachings may be relatively compact in size. In addition, it is possible to eliminate some parts of the eccentric mechanism that are required in known scroll compressors, thereby reducing manufacturing costs. 
     In another aspect of the present teachings, a plane bearing or a needle bearing may movably support at least one of the drive scroll or the driven scroll along the axial direction. In addition, a refrigerant (cooling medium) may be compressed within the compression chamber and then may be discharged to the side of the drive scroll or the driven scroll that is movably supported along the axial direction. Therefore, the pressurized or compressed refrigerant may apply a force to the rear side of one of the drive scroll or the driven scroll. The amount of force applied to the rear side of the drive scroll or the driven scroll can be selectively determined by adjusting the size of a discharge chamber that may be defined within the drive scroll or the driven scroll. That is, the area of the rear side of the corresponding scroll, to which area the discharge pressure is applied, may be selectively modified in order to adjust the amount of force applied by the pressurized refrigerant. Therefore, the contacting pressure between the drive scroll and the driven scroll can be appropriately determined. 
     In another aspect of the present teachings, a transmission or other means for rotating the drive scroll in synchronism with the driven scroll may be provided. For example, the transmission may include a first torque transmission member disposed on the drive scroll and a second torque transmission member disposed on the driven scroll. The first torque transmission member may slidably contact the second torque transmission member, so that the rotation of the drive scroll is transmitted to the driven scroll. Therefore, the driven scroll can synchronously rotate with the drive scroll and the rotational axis of the driven scroll is preferably offset to the rotational axis of the drive scroll. 
     Preferably, the first transmission member can rotate relative to and around the second torque transmission member. Further, the radius of rotation of the first transmission member may be equal to the distance between the rotational axes of the drive scroll and the driven scroll. Therefore, rotational torque may be smoothly transmitted. 
     In another aspect of the present teachings, the first transmission member may comprise one of a pin or a ring and the second transmission member may comprise the other of a pin or a ring. In that case, the pin can slidably rotate along the inner circumferential surface of the ring. In another aspect, the first transmission member and the second transmission member may comprise respective pins and a ring may couple the respective pins. In that case, the pins can slidably rotate along the inner circumferential surface of the ring. In another aspect, the first and second torque transmission members may respectively comprise a first pin and a second pin. In that case, the first pin can slidably contact and rotate around the second pin. Further, a ring may be rotatably mounted on one of the first pin or the second pin, so that the first pin or the second pin can slidably rotate around the ring. 
     Additional objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical cross-sectional view of a first representative scroll compressor; 
     FIG. 2 is a sectional view taken along line II—II shown in FIG. 1; 
     FIG. 3 is a cross-sectional view of a first representative transmission mechanism; 
     FIGS.  4 (A) to  4 (F) are views illustrating the compressor disposed in various angular positions during compressor operation; 
     FIG. 5 is a cross-sectional view of second representative scroll compressor; 
     FIG. 6 is a cross-sectional view of a second representative transmission mechanism; 
     FIG. 7 is a cross-sectional view of a third representative transmission mechanism; and 
     FIG. 8 is a cross-sectional view of a fourth representative transmission mechanism. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In one embodiment of the present teachings, scroll compressors may include a compressor housing having an inlet port and an outlet port. A drive scroll may be rotatably disposed within the compressor housing and may have a rotational axis. A driven scroll may be rotatably disposed within the compressor housing and may have a rotational axis. The driven scroll rotational axis is preferably offset to the drive scroll rotational axis. At least one compression chamber is preferably defined between the drive scroll and the driven scroll. Further, a first bearing may rotatably support the drive scroll in a cantilever manner and a second bearing may rotatably support the driven scroll in a cantilever manner. The first and second bearings are preferably disposed within the compressor housing. 
     In another embodiment of the present teachings, a transmission or other means may be provided for rotating the drive scroll in synchronism with the driven scroll. For example, the rotational axis of the drive scroll may be parallel, or substantially parallel, to the rotational axis of the driven scroll, but the respective rotational axes may be offset to each other in a direction perpendicular to the rotational axes. The transmission or rotating means may include a transmission mechanism that causes the driven scroll to revolve or orbit with respect to the drive scroll. 
     In another embodiment of the present teachings, the transmission mechanism may include at least two first members coupled to at least one of the drive scroll or the driven scroll and at least two second members coupled to at least one of the drive scroll or the driven scroll. The respective first members may slidably contact the respective second members. In that case, rotational torque may be transmitted from the drive scroll to the driven scroll as the drive scroll rotates. 
     In another embodiment, the transmission mechanism may include a first torque transmission member disposed on the drive scroll and a second torque transmission member disposed on the driven scroll. The first torque transmission member may slidably contact the second torque transmission member so that rotation of the drive scroll is transmitted to the driven scroll. Optionally, the first transmission member can rotate relative to and around the second torque transmission member. Further, the radius of rotation of the first transmission member may be equal to the distance between the rotational axes of the drive scroll and the driven scroll. 
     In another embodiment, the first transmission member may include a pin and the second transmission member may include a ring. Preferably, the pin can slidably rotate along the inner circumferential surface of the ring. 
     In another embodiment, the first transmission member and the second transmission member each include pins and a ring may couple the respective pins. In this case, the pins can slidably rotate along the inner circumferential surface of the ring. 
     In another embodiment, the first and second torque transmission members may respectively include a first pin and a second pin. In this case, the second pin can slidably rotate about the first pin. 
     In another embodiment, a ring may be rotatably mounted on one of the first pin or the second pin. In this case, the first pin or the second pin can slidably rotate around the ring. 
     In another embodiment, the drive scroll may include a first support portion rotatably supported by the first bearing and the driven scroll may include a second support portion rotatably supported by the second bearing. The first and second support portions may be respectively disposed on opposite sides of the compression chambers along the axial direction of the first and second support portions. Optionally, the first support portion may have a hollow cylindrical cross-section and the first support portion may be fitted within the first bearing. Further, the second support portion may have a hollow cylindrical cross-section and the second support portion may be fitted within the second bearing. 
     In another embodiment, an electric motor may rotatably drive the drive scroll. The electric motor may include a rotor secured to the drive scroll and a stator secured to an inner wall of the housing. Optionally, the stator, the rotor and the drive scroll may be concentrically disposed. For example, the rotor may be disposed within the stator and the drive scroll may be disposed within and secured to the rotor. 
     In another embodiment, means may be provided for permitting at least one of the drive and driven scrolls to move along the axial direction. For example, the first and/or second bearing may be designed to allow one of the drive scroll or the driven scroll to move along the axial direction. Optionally, the driven scroll can move along the axial direction and the drive scroll is fixed in position along the axial direction. 
     In addition, means may be provided for biasing the drive scroll towards the driven scroll. For example, the biasing means may include a discharge chamber defined within the housing. For example, the discharge chamber may be defined within the drive scroll or the driven scroll. The discharge chamber may communicate with the outlet port and may be disposed adjacent to the driven scroll. In one embodiment, refrigerant may be drawn into the at least one compression chamber via the inlet port and then compressed within the at least one compression chamber. Thereafter, the compressed refrigerant may be discharged into the discharge chamber and the compressed refrigerant may apply a force against the driven scroll or the drive scroll that urges the driven scroll toward the drive scroll or vice versa. Optionally, the discharge chamber may be defined within a portion of the driven scroll that is fitted with the second bearing. 
     Various methods also are taught for compressing a refrigerant using the scroll compressors, which are described above and below in further detail. Generally speaking, such methods may include drawing refrigerant into the compression chambers and rotating the drive scroll in synchronism with the driven scroll in order to generate pressurized refrigerant. In one optional method, the position of the first scroll may be fixed along the axial direction. Further, the second scroll may be biased toward the first scroll along the axial direction using the pressurized refrigerant. As a result, the second scroll may contact the first scroll and the position of the second scroll may become fixed along the axial direction. 
     Each of the additional features and method steps disclosed above and below may be utilized separately or in conjunction with other features and method steps to provide improved scroll compressors and methods for designing and using such scroll compressors. Representative examples of the present invention, which examples utilize many of these additional features and method steps in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe some representative examples of the invention, which detailed description will now be given with reference to the accompanying drawings. 
     A first representative embodiment will now be described with reference to FIGS. 1 to  4 . As shown in FIGS. 1 and 2, a first representative scroll compressor  1  may include a front cover  3  that is attached to a main housing  2  in order to close a front opening defined within the main housing  2 . Thus, the compressor housing may comprise the main housing  2  and the front cover  3 , although other housing arrangements are contemplated by the present teachings. Therefore, a substantially enclosed space is defined within the compressor housing. An electric motor  4  and a scroll compression mechanism, which may include a drive scroll  10  and a driven scroll  20 , may be disposed within the compressor housing. 
     The electric motor  4  may include an annular-shaped rotor  6  positioned or disposed within an annular-shaped stator  5 . The drive scroll  10  may be fixedly fitted within the rotor  6 . In this case, the drive scroll  10  will rotate with the rotor  6 . The driven scroll  20  may be disposed so as to oppose to the drive scroll  10 . The drive scroll  10  may include a scroll wall  12  that is formed on and extends from one side of a circular disk-like base plate  11 . Similarly, the driven scroll  20  may include a scroll wall  22  that is formed on and extends from one side of a circular disk-like base plate  21 . The drive scroll  10  and the driven scroll  20  are preferably arranged such that the scroll walls  12  and  22  engage with each other. For example, the scroll walls  12  and  22  may contact each other at a plurality of positions so as to define substantially crescent-shaped compression chambers (closed chambers)  30  between the scroll walls  12  and  22 . 
     Referring to FIG. 1, a support portion or a protruding portion  13  may extend from the base plate  11  of the drive scroll  10  on the side opposite to the compression chambers  30 . A ball bearing  14  may be disposed within the main housing  2  and may rotatably support the protruding portion  13 . Similarly, a support portion or a protruding portion  23  may extend from the base plate  21  of the driven scroll  20  on the side opposite to the compression chambers  30 . A needle bearing  24  may be disposed within the front cover  3  and may rotatably support the protruding portion  23 . Further, the needle bearing  24  may include an inner race that is fitted onto the protruding portion  23 . The rotational axis of the driven scroll  20  (i.e., the rotational axis of the protruding portion  23 ) may extend in parallel to the rotational axis of the drive scroll  10  (i.e., the rotational axis of the protruding portion  13 ) but may be offset to the rotational axis of the drive scroll  10  in a direction perpendicular to the rotational axis by a distance “e” as shown in FIGS. 1 and 2. 
     Thus, the drive scroll  10  and the driven scroll  20  are rotatably supported respectively by the main housing  2  and the front cover  3  in a cantilever manner from the sides that are opposite to the compression chambers  30 . In addition, the respective rotational axes of the drive scroll  10  and the driven scroll  20  are offset to each other. 
     Herein, the term “cantilever” is intended to encompass support structures that include a member that is supported at only one end. Thus, cantilever support structures differ from support structures in which a drive scroll or a driven scroll is supported at both sides (i.e., both sides of a drive scroll or a driven scroll are supported). For example, in the first representative embodiment, the drive scroll  20  is supported only from the side that is opposite to the compression chambers  30 . Consequently, such a support structure may be referred to as a cantilever support structure. 
     Still referring to FIG. 1, a transmission or transmission mechanism  31  may be disposed between the drive scroll  10  and the driven scroll  20 . The transmission mechanism  31  may serve to transmit the rotation of the drive scroll  10  to the driven scroll  20 , so that the driven scroll  20  will rotate in synchronism with the drive scroll  10 . As shown in FIGS. 2 and 3, the transmission mechanism  31  may include a plurality of pins  32  and a plurality of rings  33  (e.g., four pins  32  and rings  33  are shown in the first representative embodiment). The pins  32  may be attached to the outer peripheral portion of the scroll wall  12  of the drive scroll  10  and may extend forwardly from the front surface of the scroll wall  12  along the axial direction of the drive scroll  10 . The pins  32  may be spaced from each other around the circumference of the scroll wall  12  at suitable intervals. The rings  33  may be attached to the scroll plate  21  of the driven scroll  20  at positions corresponding to the pins  32 . Therefore, the pins  32  may contact the inner circumferential surfaces of the respective rings  33 . Preferably, the rings  33  may be fitted into respective circular recesses  21   a  that are defined within the scroll plate  21 . If rings  33  are incorporated into the design, the outer diameter of the scroll plate  21  preferably may be greater than the outer diameter of the scroll wall  12  of the drive scroll  10 . 
     Accordingly, as the drive scroll  10  rotates with the rotor  6 , the pins  32  may slide along the inner circumferential surfaces of the respective rings  33 . Therefore, the rings  33  will be urged to rotate about their central axes. As a result, the rotational torque of the drive scroll  10  can be transmitted to the driven scroll  20 . As shown in FIG. 3, the distance between the central axis of the ring  33  and the central axis of the pin  32  during this transmission may be, e.g., equal to the distance “e” between the rotational axis of the drive scroll  10  and the rotational axis of the driven scroll  20 . 
     FIGS.  4 (A) to  4 (F) serially depict views of the first representative embodiment as torque is transmitted via the pins  32  and the rings  33 . These figures show each rotational angle of 60° during one full or complete rotation (i.e., 360°) of the drive scroll  10 . As the drive scroll  10  rotates with the rotor  6 , the pins  32  slidably contact the inner circumferential surfaces of the respective rings  33  in order to transmit rotational torque from the drive scroll  10  to the driven scroll  20 . For example, each of the pins  32  may transmit rotational torque to the respective ring  33  only when the pin  32  is positioned within an angular range L, as indicated in FIG.  4 (A). Although the driven scroll  20  rotates in synchronism with the drive scroll  10 , the rotational axis of the driven scroll  20  is offset to the rotational axis of the drive scroll  10 . Therefore, the driven scroll  20  revolves (orbits) relative to the drive scroll  10 . 
     As a result, refrigerant is drawn into the main housing  2  via an inlet port  3   a  defined in the front cover  3 , as shown in FIG.  1 . As shown in FIG. 2, the refrigerant is then closed into the compression chamber  30  via suction ports  17   a ,  17   b  and  17   c , which ports  17   a ,  17   b  and  17   c  are defined within the base plate  21  of the driven scroll  20  and are located at an interval of an angle of 180° from each other. As the driven scroll  20  revolves (orbits) with respect to the drive scroll  10 , each compression chambers  30  will move in a direction from the outer periphery to the center of the scroll walls  12  and  22  of the drive and driven scrolls  10  and  20 . The volume of each compression chamber  30  will decrease as the compression chambers  30  move toward the inner circumferential ends of the scroll walls  12  and  22 . 
     As shown in FIG. 1, a sub suction port  18  may be defined between the protruding portion  13  and the bearing  14  and may extend through the base plate  11  of the drive scroll  10 . Therefore, the refrigerant also may be drawn into the compression chambers  30  via the motor  4  and the bearing  14 . 
     Still referring to FIG. 1, a discharge port  26  may be defined within the central portion of the base plate  21  of the driven scroll  20  and may communicate with the innermost compression chamber  30 . A discharge chamber  27  may be defined within the second protruding portion  23  on the front side of the base plate  21 . A discharge valve  28  may be disposed within the discharge chamber  27  and may serve to open and close the discharge port  26 . For example, the discharge valve  28  may be a reed valve. However, other types of valves may be utilized as the discharge valve. The front cover  3  may cover or enclose the front side of the discharge chamber  27  and may include an outlet port  3   b  that communicates with the discharge chamber  27 . A refrigerant discharge line to an outside circuit (not shown), such as an air conditioning circuit, may be connected to the outlet port  3   b.    
     According to the above-described first representative scroll compressor, both the drive scroll  10  and the driven scroll  20  are supported in a cantilever manner on one side and the other side opposite to the compression chambers  30  along the axial direction, respectively. In particular, the rotor  6  of the electric motor  4  may be secured to the drive scroll  10  so as to rotate together and the drive scroll  10  may be rotatably supported in a cantilever manner. Therefore, the support structure of the rotor  6  can be simplified as compared to known scroll compressors. In fact, the length of the rotor  6  can be shortened, as compared to known scroll compressors, by the length of a shaft that is required to support the side of the rotor  6  that opposite to the protruding portion  13  in known scroll compressors. In addition, a bearing for rotatably supporting such a shaft on the opposite side may be eliminated, which bearing is required in known scroll compressors. 
     Further, in known scroll compressors, an eccentric support mechanism must be mounted on a rotor shaft and in order to support the driven scroll. Therefore, in known scroll compressors, the axis of the driven scroll is offset to a drive scroll while both ends of the driven scroll must be supported. In the first representative embodiment, such an eccentric support mechanism may be eliminated. 
     Moreover, in the first representative embodiment, the refrigerant pressurized within the compression chambers  30  may be discharged to the side of the driven scroll  20  that is opposite to the compression chambers  30 . On the other hand, the refrigerant that is returned from an external air conditioning circuit may be drawn in the main housing  2  via the inlet port  3   a . Therefore, a relatively low-pressure region may be provided within the main housing  2 . Consequently, the main housing  2  may be constructed using a relatively thin wall, thereby reducing the total weight of the compressor  1 . Furthermore, because the temperature of the drawn (i.e., relatively low pressure) refrigerant is lower than the temperature of the discharged (i.e., relatively high pressure) refrigerant, the motor  4  can be effectively cooled by the drawn refrigerant and the motor bearings (e.g., bearing  14 ) can be effectively lubricated by lubricating oil circulated by the refrigerant. 
     A second representative embodiment, which provides an alternative arrangement of the support structure of the driven scroll  20 , will now be described with reference to FIG.  5 . In the second representative embodiment, bearing  115  generally performs the function of the bearing  24  shown in the first representative embodiment. In addition, bearing  115  may movably support the driven scroll  20  such that the driven scroll  20  can move along the axial direction. The bearing  115  may be a needle bearing as shown in FIG. 5 or may be a plane bearing. In other respects, the construction of the second representative embodiment may be the same, or substantially the same, as the first representative embodiment. 
     In the second representative embodiment, the pressure of the discharged refrigerant is applied to the front side of the base plate  21  of the driven scroll  20 . Therefore, during operation of the compressor  1 , the driven scroll  20  will be pressed against the drive scroll  10 . The amount of force applied by the discharged refrigerant, which presses the driven scroll  20  against the drive scroll  10 , may be selectively determined by adjusting the size of the discharge chamber  27  or the front surface area of the base plate  21  of the driven scroll  20 , against which the discharge pressure is applied. For example, the contacting force between the rear end of the scroll wall  22  of the driven scroll  21  and the base plate  11  of the drive scroll  10  or the contacting force between the front end of the scroll wall  12  of the drive scroll  10  and the base plate  21  of the driven scroll  20  may be appropriately determined. In addition, the relative position of the drive scroll  10  and the driven scroll  20  can be easily set. Furthermore, the cost of the bearing  115  may be reduced. 
     Although only the driven scroll  20  of the second representative embodiment can move along the axial direction, both the drive scroll  10  and the driven scroll  20  may move along the axial direction in further modifications of the present teachings. In such case, the main housing  2  and the front cover  3  may serve as stoppers and the corresponding end portions of the drive scroll  10  and the driven scroll  20  may contact the respective stoppers. Thus, the compressor housing  2 ,  3  can be utilized to limit the movable range of the drive scroll  10  and the driven scroll  20 . 
     FIGS. 6 to  8  show additional modifications of the transmission mechanism  31 , which causes the driven scroll  20  to rotate in synchronism with the drive scroll  10 . Each of these modifications may be suitably utilized with the above-described first and second representative embodiments. 
     A transmission mechanism  131  of the embodiment shown in FIG. 6 may be configured as a pin-ring-pin system and may include cylindrical pins  34 ,  35  and a free ring  36 . The pins  34  and  35  may be respectively mounted on the drive scroll  10  and the driven scroll  20 . The pins  34 ,  35  and the free ring  36  may be arranged such that the pins  34  and  35  may slidably contact the inner circumferential surface of the free ring  36 . Further, the central axes of the pins  34 ,  35  and the free ring  36  may be aligned along the same line. The free ring  36  may be disposed within a circumferential recess  21   a  formed in the driven scroll  20 . Therefore, the free ring  36  can rotate about the pin  35  within the recess  21   a.    
     A transmission mechanism  231  of the embodiment shown in FIG. 7 may be configured as a pin-pin system and may include pins  37  and  38 . This arrangement may provide a simple transmission mechanism for synchronously driving the driven scroll with the drive scroll. The pins  37  and  38  may be fixedly mounted or rotatably mounted on the drive scroll  10  and the driven scroll  20 , respectively. According to this arrangement, the pin  37  rotates around the pin  38  and the pin  37  may slidably contact the pin  38 . Thus, rotational torque can be transmitted from the drive scroll  10  to the driven scroll  20 . 
     A transmission mechanism  331  of the embodiment shown in FIG. 8 is similar to the transmission mechanism  231  shown in FIG.  7 . However, the transmission mechanism  331  differs from the transmission mechanism  231  in that a ring  39  is rotatably mounted on the pin  38 . Therefore, the pin  37  slidably contacts the ring  39  around the pin  38 . This arrangement may reduce friction during sliding contact between the pins  37  and  38  and may reduce the wear of the pins  37  and  38 . Although not shown in the drawings, a ring also may be rotatably mounted on the pin  37 . 
     Thus, each of the transmission mechanisms  31 ,  131 ,  231  and  331  may have a relatively simple construction while permitting the driven scroll  20  to smoothly rotate in synchronism with the drive scroll  10 . 
     In one additional modification of the present teachings, although the discharge port  26  is defined within the driven scroll  20  in the above representative embodiments, the discharge port  26  alternatively may be defined within the drive scroll  10 .