Patent Abstract:
A foot pedal mechanism for an elliptical exerciser comprising a frame. A pair of foot pedals are adapted to each support thereon a foot of the user standing on the elliptical exerciser. A crank for each the foot pedal is operatively connected to a respective one of the foot pedals such that a rotation of each of the crank about an axis of rotation thereof causes a first motion restriction of the respective one of the foot pedals. First linkages interconnect the cranks to the frame such that at least the axis of rotation of each of the crank is displaceable with respect to the frame to cause a second motion restriction of the respective one of the foot pedals. A combination of the first and second motion restrictions results in the foot pedals being restricted to an elliptical path of motion. The cranks are interconnected to synchronize a displacement of the foot pedals with respect to one another along the elliptical path of motion.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to elliptical exercisers and, more particularly, to foot pedal mechanisms thereof, and to a relation between upper- and lower-body workouts in elliptical exercisers.  
         [0003]     2. Description of the Prior Art  
         [0004]     Elliptical exercisers, also known as ellipticals, elliptical trainers and elliptical exercise machines, combine the natural stride provided by a treadmill and the simplicity of a stair climber. On an elliptical exerciser, a user stands upright comfortably while holding onto the exerciser&#39;s handrails and strides in either a forward or reverse motion. The handrails are often moveable and are synchronized with the pedals upon which the user strides, to provide a full upper- and lower-body workout.  
         [0005]     Elliptical exercisers are unique in their ability to put minimal stress on the joints while offering a weight-bearing workout, and this has ramifications in the inhibition of the onset of osteoporosis. The feet of the user never leave the pedals of the exerciser, thereby eliminating any impact in the workout. Therefore, there is a reduced risk of injury from overusing any given muscle group, thereby facilitating training for anyone with back, knee, hip and joint problems. The low-impact, intensive, cardiovascular workout provided by the elliptical exerciser is achieved through natural and smooth motion.  
         [0006]     The mechanisms incorporated into elliptical exercisers move in a continuous smooth motion and do not suffer the effects of direction reversal (e.g., in a stair-climber, the feet must change direction virtually instantaneously). In addition, elliptical exerciser technology provides a more functional pattern of movement. Since elliptical exercisers simulate a natural walking pattern, they can easily be accompanied by upper-body exercise. Many other devices, by their mechanical structure (e.g., treadmills) or by their pattern (e.g., cycling), do not readily adapt to upper-body workouts.  
         [0007]     The various manufacturers of elliptical exercisers have developed many iterations of this basic technology. As a result, the state of the art includes a plurality of machines that have a different “feel”—e.g., the articulation of the ankle, knee and hip can be different.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an aim of the present invention to provide a new elliptical exerciser.  
         [0009]     It is a further aim of the present invention to provide a novel foot pedal mechanism.  
         [0010]     It is a still further aim of the present invention to provide an elliptical exerciser having a foot pedal mechanism and a handlebar mechanism independent from one another.  
         [0011]     Therefore, in accordance with the present invention, there is provided a foot pedal mechanism for an elliptical exerciser comprising: a frame; a pair of foot pedals adapted to each support thereon a foot of the user standing on the elliptical exerciser; a crank for each said foot pedal, each said crank being operatively connected to a respective one of the foot pedals such that a rotation of each said crank about an axis of rotation thereof causes a first motion restriction of the respective one of the foot pedals; and first linkages interconnecting said cranks to the frame such that at least the axis of rotation of each said crank is displaceable with respect to the frame to cause a second motion restriction of the respective one of the foot pedals, a combination of said first and second motion restrictions resulting in the foot pedals being restricted to an elliptical path of motion, the cranks being interconnected to synchronize a displacement of the foot pedals with respect to one another along the elliptical path of motion.  
         [0012]     Further in accordance with the present invention, there is provided an elliptical exerciser comprising a frame; a foot pedal mechanism having a pair of foot pedals, the foot pedals being displaceable with respect to the frame according to a given path of motion and adapted to each support thereon a foot of a user standing on the elliptical exerciser, the foot pedal mechanism synchronizing a displacement of the foot pedals with respect to one another to cause a leg workout of the user; and a handlebar mechanism having a pair of handlebars pivotally mounted to the frame and adapted to be grasped by the hands of the user, the handlebar mechanism synchronizing a displacement of the handlebars with respect to one another to cause an upper body workout; wherein the foot pedal mechanism and the handlebar mechanism are independent from one another. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof and in which:  
         [0014]      FIG. 1  is a side elevational view of an elliptical exerciser in accordance with the present invention;  
         [0015]      FIG. 2  is a side elevational view of the elliptical exerciser in a first position of an operating sequence;  
         [0016]      FIG. 3  is a side elevational view of the elliptical exerciser in a position of the operating sequence subsequent to the first position of  FIG. 2 ;  
         [0017]      FIG. 4  is a side elevational view of the elliptical exerciser in a position of the operating sequence subsequent to the position of  FIG. 3 ;  
         [0018]      FIG. 5  is a side elevational view of the elliptical exerciser in a position of the operating sequence subsequent to the position of  FIG. 4 ;  
         [0019]      FIG. 6  is a side elevational view of the elliptical exerciser in a position of the operating sequence subsequent to the position of  FIG. 5 ;  
         [0020]      FIG. 7  is a perspective view of a foot pedal mechanism of the elliptical exerciser;  
         [0021]      FIG. 8  is an enlarged perspective view of a part of the foot pedal mechanism of the elliptical exerciser;  
         [0022]      FIG. 9  is an enlarged perspective view of a handlebar mechanism for synchronizing the movement of handlebars of the elliptical exerciser;  
         [0023]      FIG. 10A  is a schematic view of a foot pedal mechanism in accordance with an aspect of the present invention;  
         [0024]      FIG. 10B  is a schematic view of a foot pedal mechanism in accordance with a further aspect of the present invention;  
         [0025]      FIG. 10C  is a schematic view of a foot pedal mechanism in accordance with a still further aspect of the present invention  
         [0026]      FIG. 11  is a perspective view of an elliptical exerciser in accordance with another aspect of the present invention; and  
         [0027]      FIG. 12  is a perspective view of an elliptical exerciser in accordance with yet another aspect of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     The present invention is associated with foot pedal mechanisms for elliptical exercisers. The foot pedal mechanisms must impart an elliptical path of movement to the pedals of the exerciser. Referring to  FIG. 10A , a first foot pedal mechanism in accordance with the present invention is generally shown at  1 . The foot pedal mechanism  1  has a crank  2  connected to a foot pedal  3  by links  4 A,  4 B and  4 C. The crank  2  rotates about an axis of rotation X. The link  4 A, connected eccentrically to the crank  2 , receives the circular motion V 1  of the crank  2 . The crank  2  is linked to a frame by a link  5 , whereby the axis of rotation X of the crank  2  is displaceable. As the link  4 A is also secured to the frame, a rotation of the crank  2  will have the axis of rotation of the crank  2  achieve a rocking motion as shown by V 2 .  
         [0029]     The link  4 B is connected to a free end of the link  4 A, and will thus rock vertically (according to V 3 ) through the transmitted motion from the link  4 A. The link  4 C is connected at opposed ends to the axis of rotation X of the crank  2  and to a central portion of the link  4 B, so as to impart the horizontal rocking motion V 2  of the axis of rotation X of the crank  2 . Accordingly, the combination of the horizontal rocking motion V 2  and the vertical rocking motion V 3 , along with a synchronization with a reciprocal foot pedal for the other foot of the user, will have the foot pedal  3  move in an elliptical motion. A link  6  ensures that the foot pedal  3  remains generally horizontal.  
         [0030]     Therefore, the use of a crank enables to bring a circular motion to a foot pedal. If the axis of rotation of the crank is displaceable in translation, a circular motion typically imparted by a crank can be deformed into an elliptical motion.  
         [0031]     As a further example of this principle, a foot pedal mechanism also in accordance with the present invention is generally shown at  1 ′ in  FIG. 10B . The foot pedal mechanism  1 ′ has a crank  2 ′ that is displaceable in rotation according to V 1 ′ and that may translate along V 2 ′ on a frame. A foot pedal  3 ′ is mounted to the crank  2 ′ so as to rotate about the axis of rotation X′ of the crank  2 ′. A link  4 A′ interconnects an extension  4 B′ of the crank  2 ′ to the frame, so as to limit the translation of the crank  2 ′ along V 2 ′. By a synchronization with a reciprocal foot pedal for the other foot of the user, the foot pedal  3 ′ is displaceable along an elliptical path by the combination of the motions V 1 ′ and V 2 ′.  
         [0032]     Referring to  FIG. 10C , a foot pedal mechanism also in accordance with the present invention is generally shown at  1 ″. The foot pedal mechanism  1 ″ operates in similar fashion to the foot pedal mechanism  1 ′ of  FIG. 10B . Therefore, like elements bear like reference numerals. However, the foot pedal mechanism  1 ″ further includes a crank  6 ″ that will ensure that the foot pedal  3 ′ remains generally horizontal. The crank  6 ″ follows the action of the leading crank  2 ′.  
         [0033]     The above described foot mechanisms each have a crank whose axis of rotation is moveable, to convert a circular motion of the crank into an elliptical path of motion for the foot pedals.  
         [0034]     Referring to FIGS.  1  to  6 , an elliptical exerciser in accordance with the present invention is generally shown at  10 . The elliptical exerciser  10  has a foot pedal mechanism equivalent to the foot pedal mechanism  1  of  FIG. 10A . The elliptical exerciser  10  has various known components of typical elliptical exercisers. More precisely, the elliptical exerciser  10  has a frame  12  consisting of a base frame  14  and an upper frame  16 . A training support computer  18  is positioned at a top end of the upper frame  16 , and is in the line of sight of a user of the elliptical exerciser  10 . A fixed handlebar  20  is slideably mounted to the upper frame  16 , and is vertically displaceable so as to be adjusted before being secured to the upper frame  16 , to reach a desired height position for the user. Exercise handlebars  22  are pivotally mounted at pivot  24  to the upper frame  16  and are provided for the upper-body workout of the elliptical exerciser  10 . The exercise handlebars  22  are part of a handlebar mechanism  26  that enables the exercise handlebars  22  to be synchronized in motion. For instance, the handlebars  22  can be synchronized to a 180° out-of-phase motion with respect to one another to provide an upper-body workout similar to that of a striding cross-country skier. The handlebar mechanism  26  can also provide an adjustable resistance level to the handlebars  22 . The handlebar mechanism  26  operates independently from a foot pedal mechanism as will be described in further detail herein.  
         [0035]     The foot pedal mechanism of the elliptical exerciser  10  is generally shown at  30 . The foot pedal mechanism  30  can be separated into left and right mechanism portions. The left and right mechanism portions consist of the same components, whereby a generic mechanism will be generally described, and the reference numerals of the components of the right mechanism portion will be characterized by bearing the suffix “R” in FIGS.  1  to  8 , whereas the reference numerals of the left mechanism portion will be characterized by bearing the suffix “L” in FIGS.  1  to  8 . Any component shared by both mechanism portions will be described as such.  
         [0036]     A foot pedal  32  is provided with a foot support surface  34 , typically providing some adherence to the foot of a user of the exerciser  10 . The foot pedal  32  is pivotally mounted at a front end thereof to a horizontal displacement link  36  by pivot  38 . More precisely, as shown in  FIG. 8 , a pair of spaced plates  33  extend forwardly from the front end of the foot pedal  32 , and receive therebetween a pivot head  37  of the horizontal displacement link  36  (hereinafter the “HD link  36 ”). The HD link  36  is pivotally mounted at a free end thereof to the upper frame  16  at pivot  40 . Therefore, the front end of the foot pedal  32 , i.e., where the pivot  38  is, defines arcuate motions about the pivot  40 .  
         [0037]     Referring to FIGS.  1  to  6 , the foot pedal  32  is connected to a vertical displacement link  42  via a transmission link  44 . More precisely, the transmission link  44  is pivotally mounted at pivot  46  to a generally central portion of the foot pedal  32 . An opposed upper end of the transmission link  44  is pivotally connected by pivot  48  to the vertical displacement link  42  (hereinafter “VD Link  42 ”). The VD link  42  is pivotally connected, at a central portion thereof, by pivot  50  to the upper frame  16 .  
         [0038]     A crank link  54  has a bottom end thereof pivotally mounted at pivot  56  to the upper frame  16 . More precisely, as best seen in  FIG. 8 , the bottom end of the crank link  54  defines a sleeve freely mated to a horizontal transmission shaft  60 , which is rotatably mounted to the upper frame  16 . Therefore, the transmission shaft  60 , only one of which is provided for both right and left mechanism portions, can rotate in the upper frame  16  independently of the crank link  54 . Likewise, the crank link  54  can pivot freely about the transmission shaft  60 .  
         [0039]     Referring to FIGS.  1  to  6 , a crank wheel  52  is rotatably mounted, at a center  57  thereof, to an upper free end of the crank link  54 , so as to rotate freely with respect to this free end. However, the center  57  of the crank wheel  52  can be displaced arcuately about the pivot  56 . As seen in  FIG. 7 , the crank wheel  52  defines a pulley-shaped peripheral surface  58 .  
         [0040]     The transmission shaft  60  has pulleys  61 R and  61 L secured thereon, whereby belts  59 R and  59 L transmit motion between the two crank wheels  52 . The pulleys  61 R and  61 L and the crank wheels  52 R and  52 L are of the same diameter, respectively, whereby the crank wheels  52 R and  52 L are synchronized in motion. It is obvious that chains and gears or other similar equipment can be used instead of pulleys and belts.  
         [0041]     Referring to FIGS.  1  to  6 , the VD link  42  has a front end thereof pivotally mounted at  62  (see  FIGS. 5 and 6 ) to a radial, i.e., off-centered portion of the crank wheel  52 . Therefore, a rotation of the crank wheel  52  causes the VD link  42  to displace the transmission link  44  generally vertically, as pivot  48  can be displaceable arcuately about pivot  50 . Consequently, the movement of the transmission link  44  is transmitted to the foot pedal  32 , whose rear end, which supports a foot of the user, moves generally up and down. It is pointed out that a rotation of the crank wheel  52  will cause the center  57  thereof to perform a back-and-forth arcuate displacement about the pivot  56 , via the crank link  54 .  
         [0042]     The center  57  of the crank wheel  52  is connected to the transmission link  44  via an elliptical motion link  64 . More precisely, the elliptical motion link  64  (hereinafter the “EM link  64 ”) is pivotally mounted to the transmission link  44  at pivot  66 . As the VD link  42  is fixed to the upper frame  16 , the front end of the VD link  42 , i.e., by which it is connected to the crank wheel  52  by pivot  62 , can only rotate about pivot  50 . Accordingly, the EM link  64 , being secured to the center  57  of the crank wheel  52 , will be subjected to the arcuate displacement of the center  57  of the crank wheel  52  as described above, thereby transmitting this motion to the transmission link  44 . A combination of this arcuate displacement (causing a first motion restriction) with the generally vertical displacement (causing a second motion restriction) caused by the VD link  42  rotating about the center  57  of the crank wheel  52  will cause the pivot  66  on the transmission link  44  to be displaced in an elliptical pattern of motion. This elliptical pattern of motion is then transmitted to the foot pedal  32 , whose rear end, which includes the foot support surface  34 , will move likewise.  
         [0043]     As shown in  FIG. 8 , magnetic resistance wheels  70  are mounted to the base frame  14 , and each has a pulley section  72 , with one of the resistance wheels  70  being connected to the transmission shaft  60  via a belt (not shown). Therefore, various resistance levels can be transmitted from one of the magnetic resistance wheels  70  to the transmission shaft  60 , and this supplemental resistance will be applied against the foot pedals  32  in motion along their elliptical paths. The other one of the magnetic resistance wheels  70  is used with the handlebar mechanism  26 . The magnetic resistance wheels  70  are wired to the training support computer  18 , whereby the magnitude of the resistance can be changed by the user of the elliptical exerciser  10 . It is obvious that the training support computer  18  can be programmed to gradually increase, or provide various patterns of resistance to each of the magnetic resistance wheels  70 . As the resistance wheels  70  are independent from one another, the resistance set to the handlebars  22  and to the foot pedals  32  can be adjusted independently from one another.  
         [0044]     FIGS.  2  to  6  have been placed in order of operation sequence. Arrows A illustrate the arcuate path that each foot pedal  32  will be performing to reach the position of the subsequent figure.  
         [0045]     It is seen from FIGS.  2  to  6  that the foot pedals  32 R and  32 L are out of phase by 180° with respect to one another. Therefore, while one of the foot pedals  32  is in an upper position of the elliptical path, moving in a forward direction, the other one of the foot pedals  32  will be in a lower portion of the elliptical path, moving in a rearward direction. The foot pedals  32  can be displaced in either direction of the elliptical path. The ratios of the pulleys  61  and of the peripheral surfaces  58  of the crank wheels  52  will ensure that the foot pedals  32  are always out of phase by 180° along the elliptical path.  
         [0046]     The foot pedal  32  that will be in the upper portion of the elliptical path, on the verge of moving downwardly, will transmit motion to the other foot pedal  32  via the foot pedal mechanism  30 . The fact that the motion of the handlebars  22  is independent from the motion of the foot pedals  32  enables the adjustment of the intensity of the upper-body workout independently from the intensity level of the lower-body workout. Accordingly, if one&#39;s legs are stronger than one&#39;s arms, one may increase the intensity of the leg workout, while not altering one&#39;s upper-body workout. Furthermore, this configuration may be advantageous, as a user does not want his legs to compensate for the arms in the course of a combination of the upper-body workout and the lower-body workout. Therefore, the legs and the arms of the user will be performing exercises at different levels of difficulties, similarly to cross-country skiing for instance, so as to provide the full benefits of the workouts to the user.  
         [0047]     Referring to  FIG. 9 , the handlebar mechanism  26  includes left and right cam pulleys  122   a  and  122   b  mounted at opposed ends of a shaft  124  journaled to the upper frame  16 . The lower ends of the handlebars  22  are secured, as by welding, to respective hubs  126   a  and  126   b  which are, in turn, bolted to respective lateral outer faces of the cam pulleys  122   a  and  122   b . Ball bearings  128  are provided for limiting the axial movement of the cam pulleys  122   a  and  122   b  on the shaft  124 . Each pulley  122  has in its core a one-way clutch in the form of a clutch bearing  130  for drivingly connecting the pulley  122  to the shaft  124  in one direction, while allowing the pulley  122  to rotate freely on the shaft  124  in the opposite direction.  
         [0048]     A pair of nylon coated steel cables  134   a  and  134   b  are connected in parallel on opposed sides of the cam pulleys  122  so that when one of the cable  134  is drawn downwardly due to the rotational movement of one of the pulley  122 , it forces the other pulley  122  to rotate in the opposite direction. The cables  134  ensure joint movement of the cam pulleys  122  but in opposed directions. Each pulley  122  is provided with a pair of cable attachments  136  on opposed sides thereof. The first cable  134   a  is located on a rear facing side of the upper frame  16  and is connected at a first end thereof to the left pulley  122   a  and at a second end thereof to the right pulley  122   b . The second cable  134   b  is located on a front facing side of the upper frame  16  and is connected at a first end thereof to the left pulley  122   a  and at a second end thereof to the right pulley  122   b.    
         [0049]     A cable tensioner assembly  138  is mounted to the upper frame  16  for maintaining the cables  134  under a desired tension. The cable tensioner assembly  138  includes a support structure  140  carrying rear and front pair of cable pulleys  142   a  and  142   b  mounted on respective laterally spaced-apart idle shafts  144 . The first cable  134   a  extends over the rear cable pulleys  142   a , whereas the second cable  134   b  extends over the front cable pulleys  142   b . Elongated slots  145  are defined in the support structure  140  for receiving fasteners in order to adjustably mount the support structure  140  along the upper frame  16 .  
         [0050]     In operation, when the user pulls on the right handlebar  22  to pivot it rearwardly, the right cam pulley  122   b  rotates in the counterclockwise direction and drives the shaft  124  through the right one-way clutch  130 . The pulling action exerted by the right pulley  122   b  on the cable  134   a  causes the left pulley  122   a  to rotate freely relative to the shaft  124  in the clockwise direction, thereby pivoting the left handlebar  22  in the forward direction at the same rotational speed as the right handlebar  22  being pivoted rearwardly. Thereafter, when the user pulls with his/her left arm on the left handlebar  22  to pivot it rearwardly, the left pulley  122   a  rotates in the counterclockwise direction and transmits a torque to the shaft  124  via the left clutch bearing  130 . The pulling action exerted by the left pulley  122   a  on the cable  134   a  causes the right pulley  122   b  to rotate in the clockwise direction independently of the shaft  124 , thereby pivoting the right handlebar  22  forwardly.  
         [0051]     The shaft  124  is, thus, driven in a single direction (the counterclockwise direction in the illustrated embodiment) by the left and right handlebars  22 . In fact, the torque is transmitted to the shaft  124 , regardless of the action exerted on the right and left handlebars  22 . For instance, the pushing action on the right handlebar  22 , even though the right clutch bearing  30  rotates freely about the shaft  124 , leads the cables  134  to drive the left pulley  122   a  in the opposite direction, thereby causing the left clutch bearing  130  to transmit the torque to the shaft  124 . This permits the application of an adjustable opposition to the movement of the shaft  124  in order to vary the effort required to pivot the handlebars  22 . For instance, a primary sheave  146  could be keyed to the shaft  124  and engaged with an endless belt (not shown) to transmit a torque from the shaft  124  to a resisting or damping system (not shown) acting on one of the resistance wheel  70  ( FIG. 8 ).  
         [0052]     Referring to  FIG. 11 , an elliptical exerciser operating with the foot pedal mechanism  1 ′ of  FIG. 10B  is generally illustrated at  210 . A foot pedal mechanism is generally shown at  230 , and has left and right synchronized mechanism portions. However, for clarity purposes, only the right mechanism portion will be described herein below.  
         [0053]     The foot pedal mechanism  230  has a similar construction as the foot pedal mechanism  1 ′ of  FIG. 10B , and thus has a crank  232 , a foot pedal  233 , a link  234 A and a link extension  234 B. The crank  232  is displaceable in a translating motion onto a straight frame portion  235 . More specifically, the crank  232  has a shaft portion  236  mounted to a wheel  237  and rotating freely therein.  
         [0054]     Accordingly, the crank  232  can roll on the frame portion  235  (i.e., by the wheel  237 ) independently of the rotation of the shaft portion  236  therein. The shaft portion  236  is connected to the extension  234 B. The foot pedal  233  is connected to the free end of the crank  232 . Therefore, a rotation of the crank  232  will have the foot pedal  233  execute a rotational path about an axis of rotation  233 ′ thereof. On the other hand, the connection between the link  234 A and the extension  234 B will add a translation to the axis of rotation  233 ′ of the crank  232 . The combination of the translation motion of the axis of rotation  233 ′ of the crank  232  and the rotation of the foot pedal  233  about the axis of rotation  233 ′ of the crank  232  will result in the foot pedal  233  being displaceable along an elliptical path.  
         [0055]     The pulleys  238  and belts  239  (or alternatively, equivalent sprockets and chains or the like) are used to synchronize the motion between the left and right foot pedals. The synchronization will ensure that the foot pedals  233  follow continuous elliptical paths, with the foot pedals  233  being diametrically opposed in the elliptical paths. Links  240  act as a parallel mechanism to keep the foot pedals  233  generally horizontal.  
         [0056]     Referring to  FIG. 12 , an elliptical exerciser operating with the foot pedal mechanism  1 ″ of  FIG. 10C  is generally illustrated at  310 . A foot pedal mechanism is generally illustrated at  330 , and has left and right synchronized mechanism portions. For clarity purposes, only the left mechanism portion will be described herein below.  
         [0057]     The foot pedal mechanism  330  has a similar construction as the foot pedal mechanism  1 ″ of  FIG. 10C , and has a crank  332  and a foot pedal  333 . The foot pedal mechanism  330  differs from the foot pedal mechanism  230  of  FIG. 11  by the fact that the foot pedal  333  is retained at a rear end thereof by a second crank  332 ′. Therefore, unless otherwise indicated, like elements will bear like reference numerals. The second crank  332 ′ follows the motion of the first crank  332  by way of pulleys  334  and belt  335 . The second crank  332 ′ is similar in construction to the first crank  332 , in that it has a shaft portion freely rotatable in a wheel which rolls on a frame portion, herein frame portion  336 .

Technology Classification (CPC): 0