Patent Publication Number: US-8984918-B2

Title: Washing machine, inner tub of washing machine and balancer connection and assembly method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 2009-0077946, filed on Aug. 24, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a washing machine with a balancer to reduce unbalance of an inner tub and noise generation. 
     2. Description of the Related Art 
     In general, a washing machine rotates an inner tub containing laundry using a driving motor, thus washing the laundry. The inner tub is rotated at a low speed in regular and reverse directions during a washing operation, and is rotated at a high speed in any one direction during a spin-drying operation. 
     The inner tub includes a cylindrical drum provided with opened front and rear surfaces, a ring-shaped front surface part maintaining rigidity of the drum and forming an inlet through which the laundry is put into and taken out of the inner tub, and connected to the front surface of the drum through a curling process, and a circular rear surface part closing the opened rear surface of the drum. 
     Further, a balancer to reduce unbalance of the inner tub and noise generation due to mismatch between the center of gravity and the center of rotation of the inner tub is mounted on the outer surface of the front surface part. 
     In the conventional washing machine, the front surface part made of metal is connected to the front surface of the cylindrical drum made of metal and then the balancer is mounted on the outer surface of the front surface part, thereby complicating a manufacturing process and increasing manufacturing costs of the inner tub. 
     Further, the front surface part is generally formed by processing a stainless steel material using a separate mold set, thereby increasing the manufacturing costs of the inner tub. 
     Moreover, the conventional balancer mounted on the outer circumferential surface of the front surface part serves to remove partial disposition of mass of the laundry and thus to reduce the unbalance of the inner tub, but this structure of the balancer does not directly affect improvement of washing performance. 
     SUMMARY 
     Therefore, it is an aspect of at least one embodiment to provide a washing machine in which a balancer is directly mounted on a body of an inner tub without a front surface part of the inner tub. 
     It is another aspect of at least one embodiment to provide a washing machine which improves an assembly process of an inner tub and a balancer. 
     It is another aspect of at least one embodiment to provide a washing machine provided with a balancer which prevents deformation of an inner tub. 
     It is a further aspect of at least one embodiment to provide a washing machine provided with a balancer which improves washing performance. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     The foregoing and/or other aspects are achieved by providing a washing machine including an outer tub to store water, a body formed in a cylindrical shape provided with an opening at one surface thereof, and provided in the outer tub, and a balancer connected to an inner diameter part at the opening of the body to reduce unbalance of the body generated during rotation of the body and to reinforce the body. 
     The balancer may be mounted to contact laundry in the body. 
     A designated region of the body at the opening may have a diameter which is regular in the axial direction of the body. 
     The balancer may include an inner diameter part forming an inlet through which laundry is put into the body, and an outer diameter part contacting the inner diameter part of the body. 
     The washing machine may further include a cover to close a designated front region of the outer tub, and the balancer may further include a protrusion protruded toward the cover to guide the laundry into and out of the body. 
     A fastening guide into which a front end of the body at the opening may be inserted is provided on the outer diameter part of the balancer. 
     The balancer may further include at least one blade generating a water current during the rotation of the body. 
     The at least one blade may be provided in plural number and formed in the radial direction from the center of the balancer. 
     The balancer may be a ball balancer including a plurality of balls and a fluid provided therein. 
     The washing machine may further include at least one first blade provided on the inner diameter part of the body, and at least one second blade provided on the balancer. 
     The washing machine may further include a pair of washing units vertically stacked, and the balancer may be provided on the upper washing unit among the pair of washing units. 
     The body may include a first plurality of screw holes defined therethrough, and the balancer may include a second plurality of screw holes defined therethrough corresponding to the first screw holes, the balancer being screw-connected to the body by the first and second screw holes. 
     The foregoing and/or other aspects are achieved by providing an inner tub of a washing machine, which is rotatably provided in an outer tub to contain laundry and thus to perform washing of the laundry, includes a cylindrical body provided with an opening at one surface thereof, and a balancer including a balancer housing forming a ring-shaped flow space therein, and mass bodies moving within the flow space, if unbalance of the body due to laundry occurs during rotation of the body, to a position opposite to the laundry, wherein the balancer housing is connected directly to an inner diameter part of the body. 
     The body may have a diameter which is regular or is linearly increased or decreased in the axial direction of the body. 
     A protrusion extended in the axial direction may be formed on the balancer housing. 
     The balancer may further include at least one blade formed on a surface facing an inside of the cylindrical body. 
     The balancer housing may form an inlet through which the laundry is put into and taken out of the body. 
     A fastening guide connected with a front end of the body may be provided on the balancer housing. 
     The balancer may be a ball balancer including a plurality of balls and a fluid provided in the flow space. 
     The at least one blade may be formed opposite to the protrusion. 
     The foregoing and/or other aspects are achieved by providing an assembly method of an inner tub of a washing machine, which is rotatably provided in an outer tub to contain laundry and thus to perform washing of the laundry, includes cutting a metal plate to a designated size, forming through holes on the metal plate cut to the designated size, forming a cylindrical body using the metal plate cut to the designated size, and preparing a balancer to reduce unbalance of the cylindrical body, and connecting the balancer directly to the cylindrical body to enable an inner diameter part of the balancer to form an inlet of the cylindrical body. 
     The connection of the balancer to the cylindrical body may be achieved by contact of an outer diameter part of the balancer with an inner diameter part of a front end of the cylindrical body. 
     The assembly method may further include connecting a rear surface plate to close a rear surface of the cylindrical body to the cylindrical body before or after the connection of the balancer to the cylindrical body. 
     The foregoing and/or other aspects are achieved by providing an inner tub of a washing machine, which is rotatably provided in an outer tub to contain laundry and to perform washing of the laundry, the inner tub including: a cylindrical body provided with an opening at one surface thereof; and a balancer including a balancer housing forming a ring-shaped flow space at an outer circumferential portion thereof and configured to receive a plurality of balls therein movable within the flow space, an outer diameter part of the balancer housing being connected directly to an inner diameter part of the body. 
     The inner tub may further include at least one blade extending from the balancer housing at a surface of the balancer housing facing toward an inside of the cylindrical body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a longitudinal-sectional view schematically illustrating a washing machine in accordance with at least one embodiment; 
         FIG. 2  is an exploded perspective of an inner tub of the washing machine in accordance with at least one embodiment; 
         FIG. 3  is an enlarged view of a portion A of  FIG. 1 ; 
         FIG. 4  is a perspective view of the inner tub, which is partially cut out, of the washing machine in accordance with at least one embodiment; 
         FIG. 5  is a view illustrating a connection process of a body of the inner tub and a balancer in accordance with at least one embodiment; 
         FIG. 6  is a longitudinal-sectional view schematically illustrating a washing machine in accordance with at least one embodiment; and 
         FIG. 7  is a flow chart illustrating an assembly method of the inner tub of the washing machine in accordance with at least one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the at least one embodiment, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
       FIG. 1  is a longitudinal-sectional view schematically illustrating a washing machine in accordance with at least one embodiment,  FIG. 2  is an exploded perspective of an inner tub of the washing machine in accordance with at least one embodiment,  FIG. 3  is an enlarged view of a portion A of  FIG. 1 ,  FIG. 4  is a perspective view of the inner tub, which is partially cut out, of the washing machine in accordance with at least one embodiment, and  FIG. 5  is a view illustrating a connection process of a body of the inner tub and a balancer in accordance with at least one embodiment. 
     The washing machine in accordance with at least one embodiment includes a housing  10  provided in the shape of a box to form an external appearance of the washing machine, an outer tub  20  provided in the housing  10  to contain water, an inner tub  30  rotatably installed in the outer tub  20 , a driving motor  40  transmitting rotary force to the inner tub  30  to rotate the inner tub  30  such that laundry contained in the inner tub  30  is washed and spin-dried, a water supply device  50  to supply detergent and water to the inside of the outer tub  20 , and a drain device  60  to discharge water in the outer tub  20  to the outside of the housing  10 . 
     The outer tub  20  includes a cylindrical part  21  provided with an opening formed at one surface thereof, and a cover  22  through which an inlet  23  is defined, and through which the laundry is put into and taken out of the outer tub  20 , at the opening of the cylindrical part  21 , the cover  22  closing the remaining regions of the opening of the cylindrical part  21 . 
     Although this embodiment illustrates that the cylindrical part  21  and the cover  22  are integrally formed, the cylindrical part  21  and the cover  22  may be separately manufactured and then connected through welding or any other type of connecting method. 
     The driving motor  40  to rotate the inner tub  30  is installed at the outside of the rear surface of the outer tub  20 . The driving motor  40  includes a stator  41  fixed to the rear surface of the outer tub  20 , a rotor  42  rotatably arranged at the periphery of the stator  41 , and a rotary shaft  43  provided with one end installed at the rotor  42  and the other end passing through the outer tub  20  and installed at the rear surface of the inner tub  30 . 
     An opening  11  is formed through the front surface of the housing  10  at a position corresponding to the inlet  23  of the outer tub  20  and an inlet  31  of the inner tub  30  such that laundry is put into or taken out of the inside of the inner tub  30  through the opening  11 . A door  12  rotated to open and close the opening  11  is hinged to the front surface of the housing  10 . 
     A bellows  13  to prevent leakage of wash water is installed between the opening  11  of the housing  10  and the inlet  23  of the outer tub  20 . 
     The water supply device  50  includes first water supply hoses  51  provided in an upper region of the inside of the housing  10  to receive wash water supplied from an external water source, a detergent container  52  to mix detergent with the wash water and to transmit the wash water containing the detergent to the outer tub  20 , and a second water supply hose  53  to guide the wash water containing the detergent to the outer tub  20 . 
     The drain device  60  includes a drain pump  61  provided in a lower region of the inside of the housing  10  to drain the wash water in the outer tub  20 , and drain hoses  62  and  63  connected to the drain pump  61  to guide the wash water to the outside of the housing  10 . 
     Although this embodiment illustrates only the basic configuration of the washing machine, the washing machine may further include other devices to perform additional functions, such as a drying device. 
     The inner tub  30 , as shown in  FIG. 2 , includes a cylindrical body  70 , the inside of which is hollow, a rear surface plate  80  connected to the rear part of the body  70  to close a rear surface of the body  70 , and a balancer  90  connected to the front part of the body  70  opposite to the rear surface plate  80  to reduce unbalance of the body  70  and prevent deformation of the body  70  during rotation of the body  70 . 
     The cylindrical body  70  has a diameter which is substantially regular in the axial direction or is linearly increased or decreased. A plurality of through holes  71  connecting the inside of the body  70  and the outside of the body  70  is formed through the body  70 , and thus water supplied to the inside of the washing machine freely moves between the outer tub  20  and the inner tub  30 . 
     A plurality of screw holes  72  for connection with the balancer  90  by screws, which is separated from each other by a designated interval, is formed through the front part of the body  70  along the circumferential surface of the body  70 . However, the balancer  90  may be connected with the body  70  through any type of connection mechanism and is not limited to the screw hole and screw connection. 
     At least one first blade  74  separated from other blades by a designated interval is arranged in the axial direction on an inner diameter part  73  of the body  70 . As the inner tub  30  is rotated in the regular and reverse directions, the first blade  74  lifts the laundry and then drops the laundry to wash the laundry. 
     For example, three or more first blades  74  are provided, and are arranged at a regular angle on the inner diameter part  73  of the body  70 . If necessary, various numbers of the first blades  74  may be provided and arranged at various angles. 
     The rear surface plate  80  closes the rear surface of the body  70 , and through holes  81  having the same shape as the through holes  71  of the body  70  are formed through the rear surface plate  80 . Here, the size of the through holes  81  of the rear surface plate  80  may be equal to or differ from that of the through holes  71  of the body  70  according to design. 
     A shaft flange  82  to distribute the rotary force generated from the driving motor  40  throughout the inner tub  30  is fixed to the rear surface plate  80 , and a rotary shaft  43  is fixed to the center of the shaft flange  82 . Thereby, the inner tub  30  is rotated by the rotary force transmitted from the driving motor  40  through the shaft flange  82 . 
     The shaft flange  82  distributes the rotary force generated from the driving motor  40  throughout several portions of the inner tub  30 , thereby preventing excessive force from being applied to a specific portion of the inner tub  30 . A front end of the rotary shaft  43  is fixed to the center of the shaft flange  82  and an outer circumferential end of the inner tub  30  is fixed to an outer end of the shaft flange  82 , and thus the rotary force transmitted from the driving motor  40  through the rotary shaft  43  is distributed to the outer circumferential end of the inner tub  30 . 
     The shaft flange  82  includes a hub part  83  to which the rotary shaft  43  is fixed, and a plurality of arm parts  84  extended from the hub part  83  in the centrifugal direction, fixed to the outer circumferential end of the inner tub  30 , and separated from each other by a designated interval in the circumferential direction. In this embodiment, three arm parts  84  are provided on the shaft flange  82 , and the rotary force transmitted from the driving motor  40  through the rotary shaft  43  is distributed to three points of the outer circumferential end of the inner tub  30  through the three arm parts  84 . 
     Although this embodiment illustrates a direct drive motor as a device to rotate the inner tub  30 , a motor (not shown) fixed at the outside of the outer tub  20  and a driving belt (not shown) to transmit driving force of the motor to the rotary shaft  43  may be used. 
     The balancer  90  is installed on the front surface of the body  70  opposite to the rear surface plate  80 . The balancer  90  rapidly reduces unbalance of the inner tub  30  generated due to partial disposition of mass caused by the weight of the laundry in the inner tub  30  according to rotation of the inner tub  30 , thereby stabilizing the rotation of the inner tub  30  at an early stage. 
     The balancer  90  is ring-shaped, and is installed on the inner tub  30  concentrically with the center or rotation of the inner tub  30 . As shown in  FIGS. 2 and 3 , the balancer  90  includes a plurality of balls  91  formed in the shape of a sphere and serving as mass bodies having a balancing function, a balancer housing  93  to receive the plurality of balls  91  and guide rotation of the plurality of balls  91 , a housing cover  95  connected to the balancer housing  93  to form a race  94  in which the plurality of balls  91  move, and a viscous fluid  92  injected into the race  94  to adjust a moving velocity of the plurality of balls  91 . 
     Therefore, when partial disposition of mass in the inner tub  30  due to the weight of the laundry occurs, the balls  91  move to a position that is symmetrical with the position where partial disposition of mass in the inner tub  30  occurs, along the race  94 , thereby coping with the partial disposition of mass in the inner tub  30  and thus rapidly reducing unbalance of the inner tub  30  generated due to the partial disposition of mass in the inner tub  30 . 
     The balancer housing  93  and the housing cover  95  are injection molded products, for example, having a designated thickness to satisfy a required strength of the balancer  90 . 
     In order to reinforce the body  70  and form the inlet  31  of the inner tub  30 , the balancer  90  is connected directly to the inner diameter part  73  at the front end of the body  70 . 
     That is, the balancer  90  is connected to the body  70  under the condition that an outer diameter part  97  of the balancer  90  contacts the inner diameter part  73  of the body  70  at the front end of the body  70 , and a space formed by an inner diameter part  96  of the balancer  90  becomes the inlet  31  through which the laundry is put into and taken out of the body  70 . 
     A plurality of screw holes  93   a  corresponding to the screw holes  72  of the body  70  is formed on the balancer housing  93  such that the outer diameter part  97  of the balancer  90  contacts the inner diameter part  73  of the body  70  and then is screw-connected to the inner diameter part  73  of the body  70 . However, the connection between the balancer  90  and the body  70  is not limited thereto and may be connected with one another by any type of connection method. 
     Second blades  98 , as shown in  FIG. 5 , are provided on the rear surface of the balancer housing  93  opposite to the housing cover  95  forming the front surface of the balancer  90 . A plurality of second blades  98  may be arranged in the radial direction from the center of the balancer  90 . 
     The second blades  98  lift the laundry and then drop the laundry during the rotation of the inner tub  30 , and thus improve washing force. Further, the second blades  98  generate water current during the rotation of the body  70 , and thus add to improvement in washing force. 
     The housing cover  95  closes the front surface of the balancer housing  93  to form the race  94  within the balancer housing  93 . The housing cover  95  is connected to the balancer housing  93  through welding, for example, but may be connected by any type of connection method. 
     A fastening guide  90   a  to receive a front end  76  of the body  70  is formed in a circular shape at an external part of the housing cover  95  in the radial direction along the circumference of the housing cover  95 . 
     Therefore, as shown in  FIG. 5 , after the outer diameter part  97  of the balancer  90  contacts the inner diameter part  73  of the body  70  by inserting the front end  76  of the body  70  into the fastening guide  90   a  of the balancer  90 , the screw holes  72  of the body  70  are coincided with the screw holes  93   a  of the balancer  90 , and then the balancer  90  is connected directly with the inner diameter part  73  of the body  70  by inserting screws into the screw holes  72  and the screw holes  93   a.    
     A protrusion  99  protruded forwardly to guide laundry put into and taken out of the body  70  is formed on the housing cover  95 . 
     The protrusion  99  prevents laundry and other foreign substances from being introduced into a gap between the cover  22  of the outer tub  20  and the inner tub  30 , and maintains a regular interval between the outer tub  20  and the inner tub  30 . 
     Although this embodiment illustrates that the fastening guide  90   a  and the protrusion  99  are provided on the housing cover  95 , the fastening guide  90   a  and the protrusion  99  may be provided on the balancer housing  93 , or the fastening guide  90   a  may be provided on one of the housing cover  95  and the balancer housing  93  and the protrusion  99  may be provided on the other one of the housing cover  95  and the balancer housing  93 , according to design. 
     Further, the protrusion  99  and the second blades  98  may be separately formed and then connected to the balancer  90 , or may be formed integrally with the balancer  90  through injection molding as in this embodiment. 
     Although the balancer housing  93  and the housing cover  95  may be injection molded products, the balancer housing  93  and the housing cover  95  may be made of metal according to required strength of the balancer  90  and other designs. 
     Therefore, the balancer is connected directly to the front surface of the body of the inner tub without the conventional front surface plate connected to the front surface of the body to form the inlet, thereby simplifying a manufacturing process of the inner tub and reducing manufacturing costs of the inner tub. 
     Further, the balancer is connected to the front surface of the body to form the inlet and to reinforce the front surface of the body made of metal, simultaneously, thereby preventing deformation of the body during driving of the washing machine. 
     Moreover, the balancer is mounted on the inner diameter part of the body to contact laundry and is provided with the second blades, thereby contacting or lifting the laundry located at the front part of the inner tub and generating a current in wash water to improve washing force. That is, since the balancer is also used to wash the laundry located at the front part of the body, the body has an increased washing capacity compared with the conventional body having the same size. 
     Hereinafter, a washing machine in accordance with at least one embodiment will be described. 
       FIG. 6  is a longitudinal-sectional view schematically illustrating a washing machine in accordance with at least one embodiment. 
     In  FIG. 6 , the washing machine in accordance with at least one embodiment includes a plurality of washing units (for example, two washing units) vertically arranged to divisionally wash laundry according to amounts or kinds of the laundry. In an embodiment, a first washing unit  100  to wash a large amount (for example, 10 Kg or more) of laundry is installed at the lower part, and a second washing unit  200  to wash a smaller amount of laundry than that of the first washing unit  100  is installed at the upper part. However, either one of the first washing unit  100  or the second washing unit  200  may be able to wash a larger amount of laundry. 
     Although the first and second washing units  100  and  200  may have the same capacity, if necessary, the first and second washing units  100  and  200  may have different capacities, i.e., a large capacity and a small capacity, in respect of characteristics of the washing machine having the plural washing units  100  and  200 . Thereby, if a small amount of laundry is desired to be washed (particularly, in a boiling wash course), only the second washing unit  200  having the small capacity is operated to prevent unnecessary power consumption. 
     The basic configuration of the first and second washing units  100  and  200  of the washing machine in accordance with at least one embodiment is the same as that of the washing machine in accordance with at least one embodiment shown in  FIGS. 1 to 5 . Further, first and second cylindrical inner tubs  120  and  220  provided with a plurality of holes (not shown) are rotatably installed in first and second outer tubs  110  and  210  of the first and second washing units  100  and  200 , and driving devices to rotate first and second rotary shafts  101  and  201  connected to the first and second inner tubs  120  and  220  to perform washing, rinsing, and spin-drying cycles are respectively installed at the outside of rear surfaces of the first and second outer tubs  110  and  210 . 
     Water supply devices  140  and  240 , drain devices  150  and  250 , and other structures of the washing machine in accordance with at least one embodiment may be the same as those of the washing machine in accordance with the embodiment shown in  FIGS. 1 to 5 . 
     Further, the first and second inner tubs  120  and  220  of the washing machine in accordance with at least one embodiment may be the same as those of the washing machine in accordance with the embodiment shown in  FIGS. 1 to 5 . Particularly, a balancer  230  is connected directly to a body of the second inner tub  220  having the small capacity without the conventional front surface plate connected to the front surface of the body, and thus the second inner tub  220  may have an increased washing capacity compared with the conventional inner tub having the same size. Further, since the inner tub having the small capacity experiences limited body deformation as compared with the inner tub having the large capacity, required strength of a balancer housing and a housing cover of the second inner tub  220  may be decreased. 
     Further, the second inner tub  220  having the small capacity has a small dropping height of laundry by first blades  221 , and thus may cause deterioration of washing force. However, second blades  232  provided on the balancer  230  makes up for the deterioration of washing force. A balancer  130  may also be connected directly to a body of the first inner tub  120  without the conventional front surface plate, and may include second blades  132 , which are in addition to first blades  221  provides at the first inner tub  120 . 
     Although at least one embodiment illustrates the first and second inner tubs as having the same structure as the inner tub in accordance with the embodiment shown in  FIGS. 1 to 5 , the first inner tub having the large capacity may be configured such that a front surface plate is connected to the front surface of a body of the first inner tub and then a balancer may be installed at an outer diameter part of the front surface plate. 
     Hereinafter, an assembly method of the inner tub of the washing machine in accordance with at least one embodiment will be described. 
       FIG. 7  is a flow chart illustrating the assembly method of the inner tub of the washing machine in accordance with the embodiments of the present invention. 
     A metal plate is cut to a designated size through a blanking process according to a washing capacity (operation  300 ), and through holes  71  are formed on the cut metal plate through a piercing process (operation  310 ). A roll forming process is performed to form a cylindrical body  70  using the metal plate provided with the through holes  71  (operation  320 ), and the cylindrical body  70  is completed by bending both ends of the cylindrical body  70  contacting each other and then performing seaming and beading processes. 
     A rear surface plate  80  is connected to the completed cylindrical body  70  through a seaming process (operation  330 ). A front end  76  of the cylindrical body  70  to which the rear surface plate  80  is connected is inserted into a fastening guide  90   a  of a balancer  90 , and then the balancer  90  is connected to an inner diameter part  73  of the body  70  using screws through an outer diameter part  75  of the body  70  (operation  340 , with reference to  FIG. 4 ). 
     Here, the rear surface plate  80  may be connected to the body  70  after the balancer  90  is connected to the body  70 , and first blades  74  may be connected to the body  70  at any operation of the assembly process of the inner tub. 
     As is apparent from the above description, in an inner tub of a washing machine in accordance with at least one embodiment, a balancer is connected directly to the front surface of a body of the inner tub without the conventional front surface plate connected to the front surface of the body to form an inlet, thereby simplifying a manufacturing process of the inner tub and reducing manufacturing costs of the inner tub. 
     Further, the balancer is connected to the front surface of the body to form an inlet and to reinforce the front surface of the body made of metal, simultaneously, thereby preventing deformation of the body during driving of the washing machine. 
     Moreover, the balancer is mounted on the inner diameter part of the body to contact laundry and is provided with the second blades, thereby contacting or lifting the laundry located at the front part of the inner tub and generating a current in wash water to improve washing force. That is, since the balancer is also used to wash the laundry located at the front part of the body, the body has a substantially improved washing capacity compared with the conventional body having the same size. 
     Although at least one embodiment has been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.