Patent Publication Number: US-2019178236-A1

Title: Driving part for variable-capacity compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a drive unit for a variable capacity compressor, and more particularly, to a drive unit for a variable capacity compressor, which has a simplified structure. 
     BACKGROUND ART 
     In general, a compressor applied to air conditioning systems sucks refrigerant gas having passed through an evaporator to compress the same to high temperature and high pressure, and then discharges the compressed refrigerant gas to a condenser. As this compressor, there are used various types of compressors such as a reciprocating compressor, a rotary compressor, a scroll compressor, and a swash plate compressor. 
     The swash plate compressor includes a disc-shaped swash plate that is obliquely installed to a drive shaft rotated by power transmitted from an engine to be rotated by the drive shaft. In addition, the principle of the swash plate compressor is to suck or compress and discharge refrigerant gas by rectilinearly reciprocating a plurality of pistons within cylinders along with the rotation of the swash plate. By way of example, a variable capacity-type swash plate compressor disclosed in Korean Patent Application Publication No. 2012-0100189 includes a swash plate, which is installed to a drive shaft and has an angle of inclination varied with the thermal load, in order to regulate the discharge rate of refrigerant in such a manner that the feed rates of pistons are changed while the angle of inclination of the swash plate is varied. 
     Typically, a drive unit for a conventional variable capacity-type swash plate compressor has a structure in which a hinge pin fixedly positioned to a hub slides relative to a rotor fixed to a rotary shaft to adjust an angle of inclination of a swash plate through a shaft bush sliding about the rotary shaft. 
     However, this hinge mechanism requires the process of press-fitting the rotor to the rotary shaft, thereby causing complexity of work processes and product structures. Hence, the drive unit is disadvantageous in terms of weight, process, or price competitiveness. In addition, the drive unit is disadvantageous in that the gap between components is relatively large due to the clearance of the high mechanism. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a drive unit for a variable capacity compressor, which has a simplified structure. 
     Technical Solution 
     In accordance with one aspect of the present invention, a drive unit for a variable capacity compressor includes a drive shaft ( 100 ), one end of which is connected to a pulley of an engine, so that a driving force is transmitted from the engine to the drive shaft ( 100 ), a support balance ( 300 ) coupled to a pulley-side end of the drive shaft ( 100 ) to support a thrust bearing, a swash plate ( 500 ) spaced apart from the support balance ( 300 ) and allowing a discharge rate and a pressure of refrigerant to be regulated according to an angle of inclination of the swash plate ( 500 ), a hinge part ( 700 ) configured to connect the support balance ( 300 ) to the swash plate ( 500 ) and transmit a rotational force of the drive shaft ( 100 ) to the swash plate ( 500 ), and a friction ring module configured to control the angle of inclination of the swash plate ( 500 ) under low flow conditions by a frictional force generated between the drive shaft ( 100 ) and the friction ring module. 
     The friction ring module may include a polygonal pipe-shaped ring body ( 1000 ) fitted to the drive shaft ( 100 ) in its longitudinal direction, and a support spring ( 1100 ) fitted onto the ring body ( 1000 ). 
     Alternatively, the friction ring module may include a cylindrical ring body ( 1000   a ) fitted to the drive shaft ( 100 ) in its longitudinal direction, and a support spring ( 1100 ) fitted onto the ring body ( 1000   a ). 
     The ring body ( 1000 ,  1000   a ) may have an inner diameter smaller than an outer diameter of the drive shaft ( 100 ). 
     The ring body ( 1000 ,  1000   a ) may have an opening ( 1002 ,  1002   a ) formed in its longitudinal direction. 
     The drive unit may further include a circular or semicircular retainer ( 1300 ) disposed at one side of the drive shaft ( 100 ) facing the connected pulley to restrict movement of the friction ring module. 
     The ring body ( 1000 ,  1000   a ) may include a plurality of hooks ( 1004 ,  1004   a ) extending outward from one end thereof facing the swash plate ( 500 ) and bent toward the retainer ( 1300 ). 
     The support spring ( 1100 ) may be inserted between the hooks ( 1004 ,  1004   a ) and the ring body ( 1000 ,  1000   a ). 
     The support spring ( 1100 ) may have an inner diameter greater than an outer diameter of the ring body ( 1000 ,  1000   a ). 
     A distance between the ring body ( 1000 ,  1000   a ) and each of the hooks ( 1004 ,  1004   a ) may be larger than a thickness of the support spring ( 1100 ). 
     The ring body ( 1000 ,  1000   a ) may move along the drive shaft ( 100 ) when the angle of inclination of the swash plate ( 500 ) is changed, and be stopped by coming into contact with the retainer ( 1300 ) when the swash plate ( 500 ) is inclined at a minimum angle. 
     The ring body ( 1000   a ) may have a plurality of friction protrusions ( 1006   a ) protruding from its inner peripheral surface to the drive shaft ( 100 ). 
     In accordance with another aspect of the present invention, in a variable capacity compressor includes a drive shaft ( 100 ) rotatably supported in a housing and a swash plate ( 500 ) allowing a discharge rate of refrigerant to be variably controlled according to an angle of inclination of the swash plate ( 500 ) while a driving force transmitted to the drive shaft ( 100 ) is transmitted to the swash plate ( 500 ), the variable capacity compressor includes a friction member ( 1000 ,  1000   a ) coupled to the drive shaft ( 100 ) to be axially movable, positioned between the swash plate ( 500 ) and a support spring ( 1100 ) for applying a force in a direction of increasing the angle of inclination of the swash plate in an initial stage of operation, and configured to have a centrifugal force, wherein the friction member ( 1000 ,  1000   a ) restricts a rapid change in the angle of inclination of the swash plate ( 500 ) under low flow conditions by a frictional force generated between the friction member ( 1000 ,  1000   a ) and the drive shaft ( 100 ). 
     The friction member ( 1000 ,  1000   a ) may be modularized with the support spring ( 1100 ) to be axially coupled to the drive shaft ( 100 ). 
     Advantageous Effects 
     A drive unit for a variable capacity compressor according to exemplary embodiments of the present invention has an effect of maintaining controllability and also preventing a hunting problem caused under low flow conditions since it includes a friction ring module. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an assembled perspective view illustrating a drive unit for a variable capacity compressor at a maximum angle of inclination according to an embodiment of the present invention. 
         FIG. 2  is an exploded perspective view illustrating the drive unit for a variable capacity compressor according to  FIG. 1 . 
         FIG. 3  is a perspective view illustrating a friction ring of the drive unit for a variable capacity compressor according to  FIG. 1 . 
         FIG. 4  is a perspective view illustrating a friction ring of a drive unit for a variable capacity compressor according to another embodiment of the present invention. 
         FIG. 5  is a top view illustrating a coupled state of the friction ring according to  FIG. 4 . 
     
    
    
     BEST MODE FOR INVENTION 
     Hereinafter, a drive unit for a variable capacity compressor according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an assembled perspective view illustrating a drive unit for a variable capacity compressor at a maximum angle of inclination according to an embodiment of the present invention.  FIG. 2  is an exploded perspective view illustrating the drive unit for a variable capacity compressor according to  FIG. 1 .  FIG. 3  is a perspective view illustrating a friction ring of the drive unit for a variable capacity compressor according to  FIG. 1 . 
     As illustrated in  FIGS. 1 and 2 , the drive unit for a variable capacity compressor, which is designated by reference numeral  10 , according to the embodiment of the present invention is inserted into a compressor consisting of a cylinder block and front and rear housings. The drive unit  10  includes a pulley (not shown) that is powered by an engine, a drive shaft  100  that is coupled to the pulley to be rotated by the pulley, and a support balance  300  and a swash plate  500  that are coupled to the drive shaft. The support balance  300  and the swash plate  500  are interconnected by a hinge part  700 . A coil spring  910  and a bush  900  are coupled between the swash plate  500  and the drive shaft  100  to help initially operate the swash plate  500 . The drive unit  10  includes a friction ring module that is formed at the opposite end of the pulley connection portion of the drive shaft  100 , thereby maintaining controllability and also preventing hunting under low flow conditions. 
     One end of the drive shaft  100  is connected to the pulley to be rotatably supported by the front housing, and the other end thereof is rotatably supported by the rear housing. The drive shaft  100  has a hinge connection portion  110  that is in contact with the support balance  300 . 
     The hinge connection portion  110  serves to prevent the support balance  300  from moving to the swash plate  500  while connecting the hinge part  700  to the drive shaft  100 . To this end, the hinge connection portion  110  has a through-hole that is formed through the drive shaft  100  in the direction leading both ends of a counter weight  330  of the support balance  300  in  FIG. 1  (the direction is defined on the basis of the support balance since the support balance is fixedly coupled to the drive shaft so as not to rotate for itself). The through-bole formed in the hinge connection portion  110  may affect the stiffness of the drive shaft  100 . Therefore, it is preferable to prevent a reduction in stiffness of the drive shaft  100  by reinforcing the thickness of the drive shaft  100  in the vicinity of the through-hole. Accordingly, the hinge connection portion  110  is formed to protrude outward from the outer peripheral surface of the drive shaft  100 . 
     The support balance  300  is coupled to the pulley-side end of the drive shaft  100 , and the swash plate  500  is fitted to the drive shaft  100  in the state in which the swash plate  500  is spaced apart from the support balance  300  by a predetermined distance. 
     The support balance  300  is substituted for a conventional rotor formed integrally with lug plates, and serves to support a thrust bearing (not shown). The conventional rotor is disposed opposite to the swash plate in order to transmit rotational force to the swash plate and balance the drive unit (static balance function) since yawing is generated due to imbalance of weight when a mass is provided on the drive shaft  100 . Although the conventional rotor formed integrally with lug plates is performed for the above functions, it is difficult to reduce the size of the drive unit due to the large size and weight of the rotor and the complicated hinge structure. In addition, the drive shaft  100  or the peripheral parts thereof may be deformed in the process of press-fitting the rotor to the drive shaft  100 . Accordingly, the present invention is intended to propose the support balance  300  as a substitute for the rotor. 
     The support balance  300  includes a disc-shaped bearing support  310 , a stepped portion  312  that protrudes toward the connected pulley and has a smaller diameter than the bearing support  310 , and a ring-shaped counter weight  330  that is provided on one side of the outer peripheral surface of the bearing support  310  and has a greater radius than the bearing support  310 . 
     The stepped portion  312  is formed integrally with the bearing support  310 , and each of the bearing support  310  and the stepped portion  312  has a hollow formed at the center thereof for insertion of the drive shaft  100 . 
     The counter weight  330  is preferably disposed at the lower side of the bearing support  310  in the arrangement of the drive unit illustrated in  FIGS. 1 and 2 . The support balance  300  has an eccentric load by the one-sided counter weight  330  thereto. The counter weight  330  serves to prevent an eccentricity of weight due to the structure of the hinge part  700  for adjusting the angle of the swash plate, and is thus disposed opposite to the weighted portion of the swash plate  500  and the hinge part  700 . 
     Unlike the conventional rotor coupled by press-fit, the support balance  300  has an eccentric structure at the hollow thereof into which the drive shaft  100  is inserted. Thus, the support balance  300  is maintained in the coupled state without rotating on the drive shaft  100 . 
     The swash plate  500  is connected to a piston (not shown) inserted into a cylinder bore formed in the cylinder block. The piston reciprocates in the cylinder bore along with the rotation of the swash plate  500  to thereby suck refrigerant or compress the refrigerant in the cylinder bore. The discharge rate and pressure of the refrigerant is regulated by adjusting the angle of inclination of the swash plate  500 . 
     The swash plate  500  has a swash plate arm  510  and a hub  530  that protrude from the flat surface thereof facing the support balance  300 . The swash plate arm  510  is relatively disposed at the upper side of the swash plate  500  whereas the hub  530  is relatively disposed at the lower side of the swash plate  500  in the state in which the hub  530  is spaced apart from the swash plate arm  510 , in  FIGS. 1 and 2 . 
     The swash plate arm  510  consists of a pair of swash plate arms that face each other and are made of a sheet of metal, and the swash plate arms  510  have respective through-holes formed therein for insertion of a second hinge pin  770  to be described later. The hinge part  700  is inserted between the swash plate arms  510  to be rotatably coupled to the swash plate arms  510  by the second hinge pin  770 . 
     The hub  530  has a substantially semi-cylindrical shape, and protrudes further than the swash plate arms  510  toward the support balance  300 . The hub  530  serves to restrict the movement of the swash plate  500  such that the swash plate  500  is not inclined above a predetermined angle when the angle of inclination of the swash plate  500  is adjusted. To this end, the hub  530  preferably protrudes enough to come into contact with the support balance  300  when the swash plate  500  is inclined at a maximum angle. 
     The support balance  300  is connected to the swash plate  500  by the hinge part  700 . 
     The hinge part  700  includes a pair of first hinge arms  710  disposed at both sides of the hinge connection portion  110  of the drive shaft  100 , a second hinge arm  730  protruding toward the swash plate arms  510 , a first hinge pin  750  coupled to the first hinge arms  710 , and a second hinge pin  770  coupled to the second hinge arm  730 . 
     The first hinge arms  710  are connected to the second hinge arm  730 . The first hinge arms  710  face each other and are made of a sheet of metal. The first hinge arms  710  grasp the hinge connection portion  110  at both sides thereof and have respective through-holes formed therein for insertion of the first hinge pin  750 , in  FIG. 3 . The first hinge pin  750  is coupled to the first hinge arms  710  by passing through the through-hole of the hinge connection portion  110  through one of the first hinge arms  710  and then passing through the other of the first hinge arms  710 . The first hinge arms  710  are rotatably coupled to the hinge connection portion  110  by the first hinge pin  750 . If the hinge connection portion  110  has a curved outer peripheral surface according to the shape of the outer peripheral surface of the drive shaft  100 , the hinge connection portion  110  does not come into surface contact with the first hinge arms  710  but a gap is formed therebetween. Thus, the contact surface of the hinge connection portion  110  coming into contact with the first hinge arms  710  is preferably flat rather than curved such that the first hinge arms  710  are able to stably grasp the hinge connection portion  110 . 
     The second hinge arm  730  has a thickness corresponding to the distance between the pair of swash plate arms  510 , and has a through-hole formed therein for insertion of the second hinge pin  770 . The second hinge pin  770  is inserted into one of the swash plate arms  510 , passes through the second hinge arm  730 , and is then inserted into the other facing swash plate arm  510 . The swash plate arms  510  are rotatably coupled to the second hinge arm  730  by the second hinge pin  770 . 
     As illustrated in  FIG. 2 , the bush  900  has a cylindrical shape and is inserted between the swash plate  500  and the drive shaft  100 . The coil spring  910  is inserted between the bush  900  and the drive shaft  100 . The bush  900  is elastically supported by the coil spring  910  and slides along the drive shaft  100 . The bush  900  slides together with the swash plate  500  when the angle of inclination of the swash plate  500  is changed, with the consequence that the swash plate  500  is smoothly movable along the drive shaft  100 . 
     Meanwhile, the friction ring module is provided to prevent a hunting phenomenon in which noise occurs when the angle of the swash plate is not maintained small due to too low friction under low flow conditions. 
     As illustrated in  FIGS. 2 and 3 , the friction ring module includes a ring body  1000  and a support spring  1100 . A retainer  1300  is fitted to the opposite end of the pulley connection portion of the drive shaft  100  to restrict the movement of the friction ring module. The retainer  1300  has a circular or semicircular ring shape, and serves as a stopper. 
     The ring body  1000  has a polygonal pipe shape. A portion of the ring body  1000  is cut to form an opening  1002 , and the ring body  1000  is fitted to the drive shaft  100  in the longitudinal direction thereof. Since the ring body  1000  is not cylindrical, the ring body  1000  is coupled to the drive shaft  100  with a gap therebetween in some sections without entirely surrounding the outer peripheral surface of the drive shaft  100 . The opening  1002  is formed in the longitudinal direction of the drive shaft  100 . Preferably, the ring body  1000  has an inner diameter smaller than the outer diameter of the drive shaft  100  in the state in which the opening  1002  is not formed in the ring body  1000 . This is to generate a force in the central direction of the drive shaft  100  and thus generate a frictional force between the ring body  1000  and the drive shaft  100 . There is no problem in the assembly of the ring body  1000  because the ring body  1000  has the opening  1002  even though the inner diameter of the ring body  1000  is smaller than the outer diameter of the drive shaft  100 . The ring body  1000  has a plurality of hooks  1004  formed at one end thereof facing the swash plate  500  so that the support spring  1100  is coupled to the hooks  1004 . 
     The hooks  1004  extend outward from one end of the ring body  1000  facing the swash plate  500  and are bent toward the retainer  1300 . Preferably, the distance between each of the hooks  1004  and the outer peripheral surface of the ring body  1000  is larger than the thickness of the support spring  1100  so as not to interfere with the operation of the support spring  1100 . The support spring  1100  is inserted between the hooks  1004  and the ring body  1000 . 
     One end of the support spring  1100  is inserted between the hooks  1004  and the ring body  1000 , and the other end thereof extends toward the retainer  1300 . The support spring  1100  has an inner diameter slightly greater than the outer diameter of the ring body  1000 . 
     The reason that the hooks  1004  are formed in the ring body  1000  despite the greater inner diameter of the support spring  1100  than the outer diameter of the ring body  1000  is to smoothly assemble the support spring  1100 . That is, the hooks  1004  serve to temporarily fix the support spring  1100  in the assembly thereof to prevent the support spring  1100  from moving to the swash plate  500 . However, the hooks  1004  does not interfere with the movement of the support spring  1100  to the retainer  1300 . 
     As illustrated in  FIGS. 4 and 5 , a friction ring module of a drive unit according to another embodiment of the present invention includes a cylindrical ring body  1000   a  having an opening  1002   a  formed at one side thereof. The ring body  1000   a  has a plurality of hooks  1004   a  formed on the outer peripheral surface thereof, and may further have a plurality of friction protrusions  1006   a  protruding from the inner peripheral surface thereof to the drive shaft  100  (the same components as those of the previous embodiment will not be described in detail). 
     The friction protrusions  1006   a  serve to increase a frictional force between the drive shaft  100  and the ring body  1000   a , and to increase a force generated in the central direction of the drive shaft  100 , as illustrated in  FIG. 5 . 
     The shape of the ring body  1000   a  is not restricted. However, in the case where the ring body  1000   a  is configured to have a cylindrical shape and support the drive shaft  100  at three points by the friction protrusions  1006   a  and uses a multiple press as in the present embodiment, it is possible to enhance productivity. 
     If the frictional force is too high, there is a problem in that pressure does not change at all due to fixation of the friction ring module to the drive shaft  100 . On the other hand, if the frictional force is too low, there is a problem in that noise occurs (hunting) since it is difficult to keep the angle of the swash plate small under low load conditions. 
     In the present invention, the ring body  1000   a  has an inner diameter smaller than the outer diameter of the drive shaft  100  or has the friction protrusions  1006   a  to properly maintain the frictional force. Therefore, the drive unit has an effect of maintaining controllability and also preventing hunting under low flow conditions. 
     In the above-mentioned embodiments, the ring body  1000  or  1000   a  moves between the bush  900  and the retainer  1300  that are inserted between the swash plate  500  and the drive shaft  100 , and the movement of the ring body is stopped while the ring body is pushed by the bush  900  at the minimum angle of the swash plate  500  to come into contact with the retainer  1300 . Accordingly, the length of the ring body  1000  or  1000   a  in the longitudinal direction of the drive shaft  100  is varied depending on the position of the retainer  1300  when the swash plate  500  is inclined at a minimum angle. 
     Meanwhile, the ring body  1000  may be coupled to the drive shaft  100  to be axially movable, may be positioned between the swash plate  500  and the support spring  1100  for applying a force in the direction of increasing the angle of inclination of the swash plate in the initial stage of operation, and may be configured to have a centrifugal force. Thus, since the ring body  1000  serves to restrict a rapid change in the angle of inclination of the swash plate  500  under low flow conditions by the frictional force generated between the ring body  1000  and the drive shaft  100 , the ring body  1000  may be defined as a friction member. In addition, the ring body  1000  may be modularized with the support spring  1100  to be axially coupled to the drive shaft  100 . 
     Since the drive unit includes the friction ring module having the above-mentioned structure, it is possible to maintain controllability and prevent a hunting problem caused under low flow conditions. 
     INDUSTRIAL APPLICABILITY 
     The present invention can be applied to a drive unit for a variable capacity compressor, which has a simplified structure.