Abstract:
A metal belt, comprising a metal band ( 18 ) passed around a drive pulley ( 12 ) and a driven pulley ( 15 ) and a plurality of elements ( 19 ) disposed laminatedly in the extending direction of the band; each element being formed of wire material and further comprising a body part ( 31 ) in contact with the pulley, vertically installed parts ( 32 ) erected from both sides of the body part, and a pair of hook parts ( 33 ) which extended from the vertically installed parts and disposed opposedly to each other, wherein an opening part ( 34 ) is formed with the body part and both hook parts and, because the band ( 18 ) is inserted into the opening part ( 34 ) of each element so as to prevent the element from falling down from the band, a falling prevention body ( 20 ) is disposed in the opening part overlappingly with the band ( 18 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an endless metallic belt to be extended between a drive pulley and a driven pulley. The present invention also relates to an element constituting the metallic belt and a process of assembling the same. 
     There is known a metallic belt used, for example, in an automotive stepless variable speed device, in which a multiplicity of slat-like elements formed by punching a metal plate are layered to be slidable relative to the longitudinal direction of the belt. In this metallic belt, if the elements have corners, the corners of the elements can damage the band when they are brought into contact with it, being causative of breakage of the band. 
     However, since conventional metallic belt elements are very small and are formed by punching a plate material, it is impossible to subject the elements at the corners to chamfering or other treatments. 
     Also, since each element is made of a single plate material, the weight of the element cannot be reduced. These elements are circulated along a circular orbit over pulleys of a stepless variable speed device. However, if the element has a great mass, a great centrifugal force acts upon it accordingly. In addition, a great inertia force acts upon the element when a vehicle is accelerated or decelerated. Such excessive centrifugal force and inertia force reduce responsiveness and hinder smooth performance of the stepless variable speed device. Heavy elements cause these problems. 
     Further, since each element is made of a single plate, it hardly deforms when an execessive load or force acts upon the element when contact with pulleys occurs. Thus an element cannot release the load or force, which causes damage or abnormal abrasion of the elements and pulleys. 
     The present invention was accomplished in view of the problems inherent in the prior art technique as described above. The object of the present invention is to provide a metallic belt element that can prevent damage and abnormal abrasion in such elements, bands and pulleys and that can operate smoothly in power transmission, a metallic belt and a process of assembling the metallic belt. 
     BRIEF SUMMARY OF THE INVENTION 
     In order to attain the above object, in metallic belt element according to a first embodiment of the present invention, the metallic belt elements are supported by an endless metallic band extended between a drive pulley and a driven pulley and are layered in the longitudinal direction of the band. The periphery of the element is made of wire. 
     In a second embodiment of the present invention includes: a metallic belt having an endless metallic band extending between a drive pulley and a driven pulley; and a multiplicity of elements layered in the longitudinal direction of the band. In the metallic belt, the periphery of the element is formed of wire. The element includes a body, which contacts the pulleys, pillars, which rise from each side of the body, respectively, and a pair of hooked portions, which extends inward from the pillars and oppose each other. The body and the hooked portions define an opening. A stopper is arranged on the band within the opening to prevent the elements from slipping off the band placed in the opening. 
     The third embodiment of the present invention is a suitable process of assembling a metallic belt. According to this process, an endless belt-like stopper is located on the band. Next, the band is placed in an opening of each metallic belt element with the stopper being flexed laterally. Subsequently, the stopper is returned to a normal planar state to allow it to engage with inner side edges on both sides of the opening of each element, thus attaching the elements to the band. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view showing the metallic belt according to a first embodiment of the present invention; 
     FIG. 2 is a partially sectional side view of the metallic belt; 
     FIG. 3 is a vertical cross-sectional view of the metallic belt; 
     FIG. 4 is a front view of the element; 
     FIG.  5 ( a ) is a plan view of the element; 
     FIG.  5 ( b ) is a side view of the element; 
     FIG. 6 is a cross-sectional view of the wire; 
     FIG. 7 is a plan view of the stopper; 
     FIG. 8 is a plan view showing the state where the metallic elements are being incorporated into the band; 
     FIG. 9 is a side view showing the state where the metallic elements are being incorporated to the band; 
     FIG. 10 is a vertical cross-sectional view showing the state where the metallic elements are being incorporated into the band; 
     FIG. 11 is a plan view showing the state where the metallic elements have been incorporated fully into the band; 
     FIG. 12 is a vertical cross-sectional view showing the state where the metallic elements have been incorporated fully into the band; 
     FIG. 13 is a side view showing the variable speed device according to a second embodiment of the present invention; 
     FIG. 14 is a partial plan view of the metallic belt according to the second 
     FIG. 15 is a front view showing an element of the metallic belt shown in FIG.  14 . 
     FIG. 16 is a side view showing the element of the metallic belt shown in FIG.  14 . 
     FIG. 17 is a cross-sectional view of the wire; 
     FIG. 18 is a side view of the element according to a third embodiment; 
     FIG. 19 is a front view of the element according to the third embodiment; 
     FIG. 20 is a plan view of the element shown in FIG. 19; 
     FIG. 21 is a front view of the element according to a fourth embodiment, 
     FIG. 22 is a plan view of the element shown in FIG. 21; 
     FIG. 23 is a side view of the element shown in FIG. 21; 
     FIG. 24 is a front view of a prior art element; and 
     FIG. 25 is a front view of the prior art element. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described below specifically by way of embodiments realized in an automotive stepless variable speed device referring to the drawings. 
     First Embodiments 
     A first embodiment will be described in detail referring to FIGS. 1 to  12 . In the first embodiments, the expressions “upper” and “lower”, and “right” and “left” are referred to based on the drawing shown in FIGS. 2 or  4 . The expressions “ahead” and “behind” are also referred to based on FIGS. 2 or  4 . 
     As shown in FIG. 1, a drive pulley  12  is attached to a drive shaft  11 . A substantially V-shaped annular groove  13  is formed in the periphery of the pulley  12 , as shown in FIG. 3. A driven pulley  15  is attached to a driven shaft  14 , which corresponds to the drive shaft  11  in the drive pulley  12 , and a substantially V-shaped annular groove  16  is formed in the periphery of the pulley  15 . An endless metallic belt  17  extends between the two pulleys  12  and  15  and engages with the annular grooves  13  and  16  to transmit rotation of the drive pulley  12  to the driven pulley  15 . 
     As shown in FIGS. 2 and 3, the metallic belt  17  is made essentially of an endless metallic band  18 , a multiplicity of metallic elements  19  and an endless belt-like metallic stopper  20 , which is slightly wider than the band  18 . The elements  19  are layered and are slidable relative to one another in the longitudinal direction to allow insertion of the band  18  through them. The band  18  is formed by laminating a plurality of metal sheets and is subjected to surface treatment on both sides or on one side by sand blasting or shot peening. This surface treatment permits a lubricant to be carried to reduce frictional resistance between the band  18  and each element  19 . 
     As shown in FIGS. 4 to  6 , each element  19  is made by cutting a metallic wire  19   a , which has a circular cross section and which is formed by drawing, into pieces of a predetermined length, bending the resulting pieces into the form of element  19 , and pressing the resulting pieces. Each element  19  has a symmetrical form. The chain double-dashed lines in FIGS.  4  and  5 ( a ) each show the shape of the element  19  before the pressing. Further, the entire outer surface of each element  19  is treated by sand blasting or shot peening like in the case of the band  18 . The surface treatment carries a lubricant to reduce frictional resistance between the elements  19 . Each element  19  has a hook-like pillar or rising portion  32  extending upward from each side of the upper face of a body  31 . An opening or recess  30  is defined between the pillars  32  for receiving the band  18  and the stopper  20 . The tips of the pillars  32  are bent inward to form engaging protrusions  33 . An opening  34 , which is slightly wider than the band  18  and slightly narrower than the stopper  20 , is defined between the engaging protrusions  33 . Each element  19  is supported at the recess  30  by the band  18 . 
     The shoulder  35  of the body  31  on which the band  18  is placed has an arcuate shape, which projects gently upward to prevent winding of the band  18 . When an excessive downward load is applied to the body  31 , the shoulder  35  flexes to have a gentler curvature (to be almost linear), which reduces stress. 
     A first slope  36  is formed on one side of each element  19  of the body  31  by polishing. The first slope  36  is formed such that the thickness of the body  31  decreases gradually in the downward direction of FIGS.  4  and  5 ( b ). The first slope  36  allows the row of elements  19  to curve along the periphery of the pulleys  12  and  15  when engaged with them. The body  31  has, on both ends, second slopes  37 , which are inward slopes, in the view of FIG.  4 . The second slopes  37  are formed by polishing. As shown in FIG. 3, the second slopes  37  are engaged with the inner side faces of the annular groove  13 ( 16 ) of the pulley  12 ( 15 ) 
     A boss  38  is formed by pressing at the center of the body  31 , and a depression  39  is formed on the other side of the body  31  in alignment with the boss. Every two adjacent elements  19  engage with each other by the boss  38  and the depression  39 , and thus the elements  19  are connected to one another in alignment. 
     As shown in FIG. 7, a plurality of slots  40  are defined in the stopper  20 . Also, small holes  40   a  are defined adjacent to the slots  40 . While the slots  40  are defined in the stopper  20  in pairs at equal intervals, they may be continuous and formed all around the stopper  20 . Further, the stopper  20  may have, on both side or on one side surface, surface treatment formed by means of sand blasting or shot peening, which carries a lubricant to reduce frictional resistance among the stopper  20 , the outermost layer of the band  18  and the elements  19 . 
     The stopper  20  can be switched between a normal or a wide state, which is shown in FIGS. 11 and 12, and a curved or narrow state, which is shown in FIGS. 8 and 10. The stopper  20  is fitted on the periphery of the band  18 , and the width of the stopper  20  in the wide state of FIG. 7 is then reduced to the narrow or flexed state shown in FIGS. 20 and 8 by engaging tools (not shown) with the small holes  40 a to flex and reduce the width of the stopper  20 . When the stopper  20  is in the curved state, it is designed to be slightly narrower than the width of the opening  34  of the element  19 . As shown in FIG. 9, the elements  19  are fitted to the band  18  through the opening  34  of each element  19  so that they are supported by the band  18 , and they are slid one after another toward a wider portion of the band  18 . When the elements  19  are all fitted to the band  18 , the tools are disengaged from the stopper  20 . The stopper  20  then resumes the and flat state, and the ends of the element  19  engage the engaging protrusions  33  respectively, as shown in FIGS. 11 and 12. In this state, the elements  19  are prevented from slipping off the band  18 . 
     Next, the effects of the above embodiment exhibits will be described. 
     In this embodiment, since each element  19  is provided with an opening  34  having a suitable width with respect to the width of the band  18 , the weight of the elements  19  is reduced, and the weight of the entire metallic belt  17  is reduced. Actually, a 20 to 30% weight reduction was achieved in the metallic belt. Since this reduces the inertia force, the belt  17  is expected to show improved response to acceleration, deceleration and the like. Further, since each element  19  is made from a drawn wire, it is inexpensive. In addition, since each element  19  is obtained by subjecting wire, which has a circular cross section, to press molding, the elements  19   a  do not have corners like those obtained by punching a plate. Therefore, the elements  19  give no substantial damage to the band  18  and the stopper  20 , which improves the durability of the metallic belt  17 . Since each element  19  has a pillar  32  on each side, it is durable and resists from damage. 
     In the state where elements are supported by the band, it is necessary to prevent the elements from slipping off the band, and measures have been proposed for this purpose. Japanese Unexamined Patent Publication No. Sho 55-100443 discloses a typical construction, as shown in FIG.  24 . In FIG. 24, an element  301 , which engages a band  300 , includes a recess  302  that opens laterally. In the apparatus shown in FIG. 24, the element  301  includes a pair of recesses  302  that open laterally. Japanese Unexamined Patent Publication No. Sho 62-35136 discloses an apparatus as shown in FIG. 25, in which, after a band  300  is placed in a recess  302  of an element  301 , a cross piece  304  is placed across the opening of the recess  302 . 
     However, in the apparatus shown in FIG. 24, the element  301  may slip off the belt  300  through the lateral opening. In the constitution shown in FIG. 25, the cross pieces  304  must be fixed to a multiplicity of elements  301  by means of welding or the like, after the elements  301  are incorporated into the band  300 . This is a difficult task, since the elements  301  are small. Besides, a cross piece  304  must be prepared for each element  301 . This increases the number of parts and makes the apparatus complicated. 
     In the first embodiment of the invention, the engaging protrusions  33  of the element  19  engage with the stopper  20  to securely prevent the element  19  from slipping off. Incorporation of a single stopper  20  does not make the apparatus complicated compared with the prior art, for example, as shown in FIG. 25, in which each element is provided with a cross piece  304  for presenting the elements from slipping off from the band. 
     Since the elements  19  are supported by the band  18  by using the flexibility of the stopper  20 , they can be incorporated into the belt very easily. 
     The slots  40  and small holes  40   a  defined in the stopper  20  for flexing contribute to reducing the weight of the metallic belt. 
     Second Embodiment 
     A second embodiment of the present invention will be described specifically referring to FIGS. 13 to  17 . In the second embodiment, the expressions “upper” and “lower”, and “right” “left” are based on the drawing shown in FIG.  15 . The expressions “ahead” and “behind” are also based on FIG.  15 . 
     As shown in FIGS. 13 and 15, a drive pulley  112  is attached to a drive shaft  111 . A substantially V-shaped annular groove  112   a  is formed on the periphery of the pulley  112 . A driven pulley  114  is attached to a driven shaft  113 , which corresponds to the drive shaft  111 , of the drive pulley  112 , and a substantially V-shaped annular groove  114   a  is formed on the periphery of the pulley  114 . An endless metallic belt  115  extends between the drive pulley  112  and the driven pulley  114  to engage with the annular grooves  112   a  and  114   a  to transmit rotation of the drive shaft  111  through the drive pulley  112 , the metallic belt  115  and the driven pulley  114  to the driven shaft  113 . 
     As shown in FIGS. 14 and 15, the metallic belt  115  includes essentially a pair of endless metallic bands  116  and a multiplicity of metallic elements  117 . The elements  117  are layered between the bands  116  to be slidable relative to one another in the longitudinal direction of the bands  116 . 
     Each band  116  is formed by laminating a plurality of endless belt-like bodies  118 , each made of a metal sheet, and each endless belt-like body  118  has surface treatment  118   a  on both sides or on one side. The surface treatment  118   a  is formed, for example, by a treatment or embossed pattern formed on the periphery of a roller, which is used when the endless belt-like body  118  is fed through a plurality of rollers. Otherwise, the surface treatment is formed by subjecting the endless belt-like body  118 , which is rolled into a predetermined thickness, by sand blasting or shot peening to produce very small dimples, each having a substantially arcuate cross section. Formation of the surface treatment  118   a  reduces the contact surface area among the endless belt-like bodies  118  in each band  116  and between the band  116  and each element  117 . The surface treatment also permits a lubricant to be carried in the dimples. Thus, frictional resistance among the endless belt-like bodies  118  and between the bands  16  and each element  117  is reduced. 
     As shown in FIGS. 14 to  17 , each element  117  is obtained by bending a metallic wire  124 , which has a substantially rectangular cross section and a predetermined length, to form an entire element  117 . Each element  117  has a symmetrical form. The elements  117  are obtained by cutting a metallic wire  124  into a predetermined lengths and bending the resulting pieces. Abutting portions, which are indicated by the chain double-dashed lines circles  150  in FIG. 15, are welded, Thus, empty spaces S are defined in the wire  124 . 
     The wire  124  is made of a ferrous metal such as a high carbon steel wire rod. Each element  117  has a surface treatment  117   a  over its entire outer surface formed by sand blasting or shot peening. The surface treatment permits a lubricant to be carried to reduce frictional resistance between the elements  117  and between the bands  116  and each element  117 . 
     Each element  117  has a body  119  and heads  120  formed integrally therewith through center pillars  121 . The heads  120  extend from the body  119  through the pillars  121 . A pair of slits  125 , in which the bands  116  are inserted, is defined on one side of each pillar  121 . The bands  116  run through the slits  125 , and the heads  120  prevents the elements  117  from slipping off of the bands. 
     The shoulders  127  of the body  119  are located below the slits  125 , on which the bands  116  are placed. Each shoulder  127  has an arcuate shape and projects gently to prevent winding of the bands  116 . The tips  128  of the heads  120 , which are above the slits  125 , are arcuately curved upward, so that the tips  128  do not interfere with the surfaces of the bands  116 . 
     A pair of first slopes  119   a  are formed on one side of the body  119  on each element  117 . The first slopes  119   a  are formed such that the thickness of the body  119  decreases gradually in the downward direction in FIG.  16 . The body  119  in each element  117  also has, on both ends, second downward slopes  119   b . The second slopes  119   b  are engaged with the inner side faces of the annular grooves  112   a ( 114   a ) of the pulley  112 ( 114 ). When the drive pulley  112  is rotated, the metallic belt  115  is circulated to transmit rotation to the driven pulley  114 . When the width of the annular groove or grooves  112   a / 114   a  in one of or both of the pulleys  112  and  114  is changed due to a change in the torque of the drive side or the driven side, the elements  117  shift in the radial directions of the pulleys  112  and  114 , accordingly. 
     A protrusion or boss  130  is formed at the center of the body  119 . The boss  130  has, on each side, tapered faces  130   a , which are widest at the upper end of the body  119  and which taper downward to be more narrow toward the lower end of the body  119 . Each boss  130  has on the rear side a depression  131  conforming to the shape of the boss  130 . Thus, the width of the boss  130  and that of the depression  131  change continuously along the inner wall surfaces of the annular grooves  112   a  and  114   a  of the pulleys  112  and  114  to increase from the bottom of each groove toward the opening. Every two adjacent elements  117  are engaged with each other by the  130  and the depression  131  to prevent the elements  117  from becoming misaligned. 
     As shown in FIG. 17, the wire  124  is arcuately chamfered at each of the four corners  123 . Thus, the element  117  has no comers on the periphery that can damage the surfaces of the bands  116  and the inner surfaces of the annular grooves  112   a  and  114   a  of the pulleys  112  and  114 . 
     The element  117  is obtained by cutting the wire  124 , which has a cross-sectional profile as shown in FIG. 17, into a predetermined length, followed by bending. The ends of the wire  124  abut against one another at the pillars  121 . The abutments may be mere abutment or may be fixed by welding. The wire  124  is obtained by extrusion or cold rolling. Thus, arcuate chamfers are formed at the comers  123  simultaneously when the material  124  is extruded, and the thus molded wire  124  has a mirror surface. 
     Next, the effects of the second embodiment will be described below. 
     In this embodiment, each element  117  is formed by wire  124 , so that the comers  123  of the wire  124  can be chamfered easily when the material  124  is extruded, as described above. The arcuately chamfered corners  123  prevent damage to the bands  116  and pulleys  112  and  114 , which improves the durability of the metallic belt  115 . 
     Only the outer structure of each element  117  is formed by the wire  124 , and empty spaces S are defined therein. This reduces the weight of each element  117  and of the metallic belt  115 . Therefore, the centrifugal force of the metallic belt around the peripheries of the pulleys  112  and  114  and the inertia force in response to acceleration and deceleration is reduced, which results in excellent response and smooth performance in power transmission. 
     Since each element  117  is formed by the wire  124 , each element  117  flexes slightly inward when an excessive load or force acts upon it. For example, when an inward pressure is applied to the second slopes  119   b  of each element  117  by the pulleys  112  and  114 , the elements  117  flex slightly inward accordingly. This releases the load or force and prevents damage to or abnormal abrasion of the pulleys  112  and  114  and the elements  117 , which improves the durability of the metallic band  115 . 
     Since the wire  124  has substantially rectangular cross section, the elements  117  can be layered neatly in face to face contact with one another along the longitudinal direction of the bands  116 , which prevents vibration and noise and improves power transmission efficiency. 
     The entire periphery of each element  117  is composed not of faces formed by cutting but of faces formed by cold rolling. Therefore, even if each element  117  is subjected to sand blasting or other treatment, the flat surfaces are merely roughened without marring the surface flatness. This ensures surface contact between the elements  117  and contributes to efficient power transmission. 
     Since the shoulders  127  each have an arcuate shape, they prevent winding of the bands  116 , preventing damage of the bands  116  and elements  117 . 
     Since the tips of the heads  120  are arcuately curved upward, damage to the tips  128  of the heads  120  and to the bands  116  is prevented. 
     Third Embodiment 
     A third embodiment will be described referring to FIGS. 18 to  20 . The third embodiment is a modification of the second embodiment. The tips  128  of the heads  120  in the third embodiment are curved forward. Therefore, in the third embodiment, the elements  117  can be maintained in alignment by engagement between the tips  128  of every adjacent two elements  117 . 
     Fourth Embodiment 
     A fourth embodiment will be described referring to FIGS. 21 to  23 . The fourth embodiment is a modification of the first embodiment. A pair of protrusions  55  are formed on each side pressing in the fourth embodiment. The protrusions  55  are formed on each side of the body  31  diagonally and symmetrically with respect to a plane Q including the circulating face of the element  19 . Each protrusion  55  has a fixed width and a depression  56  formed on the rear side in alignment with the protrusion  55 . 
     If an excessive load is applied downward to the body  31 , the shoulder  35  flexes to have a gentler curvature (to be almost linear), which reduces stress. 
     Other Embodiments 
     For example, the shape of the element  19  in the first embodiment can be modified variously. For example, through holes may be formed in the body  31  reduce the weight. 
     While slots  40  and the like are formed in the stopper  20  of the first embodiment, the shape of the slots  40  is not limited to that illustrated in FIG. 7, but various shapes may be used including a simple square and a rhombus. 
     In the first embodiment, the shape and the size of the boss  38  formed on the body  31  are not limited as long as every adjacent two elements  19  connect to each other without slipping off and the metallic belt  17  can maintain its function. For example, the boss  38  may have a square cross section. The shape of the depression  39  conforms to the shape of the boss  38 . 
     In the first embodiment, the boss  38  and the depression  39  are formed on the body  31 . However, they may be formed on other portions, as long as every adjacent two elements  19  are connected to each other without slipping off and the metallic belt  17  can maintain its function. They may be formed on the pillars  32 . The connection between every adjacent two elements  19  may not depend on the engagement between the boss  38  and the depression  39 , and the lower end of the body  31  or tips of the engaging protrusions  33  may be curved depending on the direction of connecting the elements  19  to achieve engagement among the thus curved portions. 
     In the first embodiment, the stopper  20  was bent when the elements  19  were engaged with the band  18 . However, it is also possible to orient the element  19  diagonally with respect to the stopper  20  to bring one side edge of the stopper  20  into the recess  30 . Then, the element  19  is turned around that side end to place the band  18  in the recess  30 . 
     In each element  117 , abutting portions of the wire  124  may be welded at position different from those illustrated in each embodiment. 
     In the third embodiment, the tips  128  of the heads  120  may be curved in the opposite direction or backward in the view of FIG.  20 . 
     The corners  123  of the wire  124  may be chamfered not arcuately but linearly. 
     The empty spaces S defined in the elements formed by the wire  31  and  124  respectively may be packed with a synthetic resin material for absorption of vibrations, noises, etc. 
     Two or more kinds of metallic materials are provided for elements  19  and  117 , and these material are arranged or layered to be adjacent to different materials respectively. This constitution can reduce vibrations, and noises due to the difference in the natural frequency between the adjacent elements  19 ( 117 ). 
     Different materials from that employed in the above embodiments maybe used for the elements  19  and  117 . There may be used, for example, ferrous metals other than hard steel and stainless steel. 
     The elements  19  and  117  may be subjected to surface hardening treatment at the shoulders  35  and  127  of the body  31  and  119  and at the second slopes  37  and  119   b  in the elements  19  and  117 . 
     A super hard metal power is sprayed over the shoulders  35  and  127  of the body  31  and  119  and over the second slopes  37  and  119   b  of the elements  19  and  117 , and the powder is melted by heating and solidified to form a super hard alloy layer. 
     In the present invention, the element is formed using a wire. This can prevent damage of the bands and the like. Further, the weight of the element can be reduced compared with the case where the element is formed using a plate material. In addition, if an excessive load or force is acted upon the element, it can flex slightly accordingly to release the load or force, preventing damage and abnormal abrasion of pulleys and elements.