Endless belt power transmission systems or components – Friction drive belt – Including link-chain coextensive with continuous surface belt
Reexamination Certificate
1999-08-31
2001-08-07
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Friction drive belt
Including link-chain coextensive with continuous surface belt
C474S242000
Reexamination Certificate
active
06270437
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to belts for a continuously variable transmission comprising metal rings formed as endless bands and a large number of metal elements supported along the metal rings, the belts transmitting drive power by being wrapped around a drive pulley and a driven pulley.
2. Description of the Prior Art
Since the durability of such belts for a continuously variable transmission is determined primarily by the durability of the metal rings, attempts have been made to enhance the durability by increasing the lateral width of the metal rings thereby decreasing the tensile stress.
Furthermore, Japanese Patent Publication No. 5-48364 describes a case where the metal rings are prevented from moving towards the neck parts of the metal elements by setting the circumference of the metal ring which is in contact with the saddle surfaces of the metal elements, which have been subjected to crowning, so that it is short at the lateral outer side and long at the lateral inner side.
When there is misalignment between the drive pulley and the driven pulley accompanying a change in the gear ratio of the continuously variable transmission, the metal rings move in a lateral direction inside the ring slots of the metal elements. Therefore, if the lateral width of the metal rings is increased in an attempt to enhance the durability thereof, a problem is caused in that the lateral edges of the metal rings come into contact with the neck parts of the metal elements or the V-faces of the pulleys and are worn. Moreover, there is a problem that due to the increase in the lateral width of the metal rings the lateral inner edge of the metal rings overhangs the saddle surfaces of the metal elements by a large amount when there is a misalignment, and thus flexural stress is applied to the metal rings thereby reducing their durability.
Furthermore, the case described in the above-mentioned publication has the problem that when the drive pulley and the driven pulley are misaligned, it is difficult to prevent the metal rings from coming into contact with the neck parts of the metal elements or the V-faces of the pulleys with certainty and no consideration is given to assuring the maximum power transmission capacity of the metal belt.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above-mentioned circumstances, and it is an object of the present invention to increase the transmission capacity and durability of the metal belt by defining an appropriate value for the contact ratio which is determined by dividing the lateral width of the saddle surface of the metal element by the lateral width of the metal ring.
In order to achieve the above-mentioned object, the invention is directed to a belt for a continuously variable transmission comprising right and left metal rings formed as endless bands and a large number of metal elements supported along the metal rings, the belt transmitting drive power by being wrapped around a drive pulley and a driven pulley. The metal elements comprise right and left ring slots which extend from a neck part in directions away from each other and are open at the sides at which they face the V-faces of the drive pulley or the driven pulley. The radially inner surfaces of the right and left metal rings which fit into the ring slots with a gap in the lateral direction, are in contact with the saddle surfaces of the metal elements. The contact ratio determined by dividing the lateral width of the saddle surface by the lateral width of the metal ring is defined as being between an upper limit and a lower limit, the upper limit being defined as a contact ratio at which, the contact ratio is decreased by increasing the lateral width of the metal rings in a state in which the lateral inner edges of the metal rings are in contact with the neck parts of the metal elements. An increase in transmission capacity due to the increase in lateral width of the metal rings is counterbalanced by a decrease in transmission capacity due to the overhang of the metal rings from the saddle surfaces. The lower limit is defined as a contact ratio at which, when the contact ratio is decreased in a state in which the lateral inner edges of the metal rings are in contact with the neck parts of the metal elements, the lateral outer edges of the metal rings coming into contact with the V-faces of the drive pulley or the driven pulley.
Further, when misalignment is present between the drive pulley and the driven pulley, the lower limit is defined as a contact ratio at which the lateral outer edges of the metal rings come into contact with the V-faces of the drive pulley or the driven pulley.
The present invention is also directed to a belt for a continuously variable transmission comprising a metal ring formed as an endless band and a large number of metal elements supported along this metal ring, the endless band and metal elements transmitting drive power by being wrapped around a drive pulley and a driven pulley. The metal elements comprise right and left ring slots which extend from right and left neck parts in directions towards each other and are open at the sides at which they face each other. The radially inner surface of the metal ring which fits into the ring slots with a gap in the lateral direction, and is in contact with the saddle surface between the right and left ring slots. The contact ratio determined by dividing the lateral width of the saddle surface by the lateral width of the metal ring is defined as being between an upper limit and a lower limit. The upper limit is defined as a contact ratio at which, the contact ratio is decreased by increasing the lateral width of the metal ring in a state in which one lateral edge of the metal ring is in contact with the neck parts on one side of the metal elements. An increase in transmission capacity due to the increase in the lateral width of the metal ring is counterbalanced by a decrease in transmission capacity due to the overhang of the metal ring from the saddle surface. The lower limit is defined as a contact ratio at which, when the contact ratio is decreased in a state in which one lateral edge of the metal ring is in contact with the neck parts on one side of the metal elements, the other lateral edge of the metal ring comes into contact with the neck parts on the other side.
Further, when misalignment is present between the drive pulley and the driven pulley, the lower limit is defined as a contact ratio at which the other lateral edge of the metal ring comes into contact with the neck parts on the other side.
By gradually increasing the lateral width of the metal rings in a state in which the lateral outer edges of the metal rings are in contact with the V-faces of the pulleys so as to gradually decrease the contact ratio, a positive percentage change in power transmission capacity is maintained. By gradually increasing the lateral width of the metal rings in a state in which the lateral inner edges of the metal rings are in contact with the neck parts of the metal elements so as to gradually decrease the contact ratio, the percentage change in power transmission capacity gradually increases from the negative side as a result, and becomes positive at a predetermined contact ratio. Therefore, by setting the predetermined contact ratio at which the percentage change in power transmission capacity changes from negative to positive as the maximum contact ratio, the percentage change in power transmission capacity can be prevented from becoming negative and thus degradation of the transmission capacity and the durability of the metal rings can be prevented.
When the contact ratio is further decreased by further increasing the lateral width of the metal rings, since the lateral outer edges of the metal rings come into contact with the V-faces of the pulleys, by setting the contact ratio at this point to be the minimum contact ratio, degradation of the durability due to the lateral edges of the metal rings coming into contact with both the n
Shimada Takamichi
Yoshida Hideaki
Arent Fox Kintner Plotkin & Kahn
Bucci David A.
Charles Marcus
Honda Giken Kogyo Kabushiki Kaisha
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