192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2001-11-14
2003-07-29
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S080000
Reexamination Certificate
active
06598719
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a one-way clutch of simple construction and low cost for which no high precision is required.
DESCRIPTION OF THE PRIOR ART
As for example disclosed in Japanese Unexamined Patent Publication No. 2869062, there is known a simple one-way clutch for low torque transmission in which is applied the principle of a two-shaft belt power transmission mechanism for transmitting torque between two shafts by way of a belt looped therebetween.
This clutch includes a first rotation member of flat pulley shape that is coupled to either one of the drive and driven sides, and a second rotation member that is assembled rotatably with the first rotation member and coupled to the other of the drive and driven sides. Radially outside of the first rotation member is disposed a shaft member which is in parallel with the rotation axis of both the rotation members, and both ends of the shaft member are pressed into corresponding shaft bores provided in the second rotation member, respectively. A rocking member of substantially arcuate cross section is supported for rocking motion on the shaft member. A belt is looped between the outer periphery of the rocking member and the outer periphery of the first rotation member so that it creates two spans therebetween. On the other hand, attached to the second rotation member is a biasing means for tending to radially inwardly press one end of the rocking member in a circumferential direction thereof, whereby the other end of the rocking member in the circumferential direction radially outwardly presses one span of the belt to place an initial tension on the belt.
When torque is input to the clutch in a direction to relatively rotate both the rotation members such that the span pressed by the biasing means will provide a slack-side span, the belt tension is maintained or increased and therefore the torque is transmitted between the first and second rotation members via the belt. In contrast, when torque is input to the clutch in a direction to relatively rotate both the rotation members such that the span pressed by the biasing means will provide a tight-side span, the belt tension is reduced so that the belt slips on at least one of the outer peripheries of both the rocking member and the first rotation member, which blocks torque transmission.
While a typical conventional one-way clutch is a precision machinery component in which a plurality of intermediate members are arranged for establishing and blocking torque transmission between inner and outer rings and a spring member is provided for urging each of the intermediate members in a direction to allow for torque transmission, the belt-type one-way clutch as described above needs no highly precise parts and has a simplified construction. Therefore, the belt-type one-way clutch has the advantage of being manufactured at low cost.
Further, when excessively large torque is input to the clutch, the belt can be broken to block further torque transmission. This also offers the advantage of low cost in that there is no need for the clutch to additionally include a torque limiter. In addition, the belt-type one-way clutch is also economically advantageous in that even if the belt has been broken, the clutch can be used again by replacing the broken belt with new one.
Meanwhile, since the belt-type one-way clutch originally has a simpler construction as compared with the typical one-way clutch, it can only necessarily transmit relatively small torque. In terms of its use, however, there is a strong demand for such a clutch that transmits as large torque as possible even if it is for low torque transmission.
In order to increase the magnitude of transmittable torque of the belt-type one-way clutch, the following several measures have been required:
1) to enhance the tensile strength of the belt;
2) to enhance the strength of the rocking member receiving pressure due to a belt tension with a smaller area than the first rotation member; and
3) to enhance the strength of the shaft member which supports the rocking member thereon.
Further, as a user side demand, weight reduction is also strongly needed in addition to rise in transmittable torque magnitude. In this respect, making the second rotation member from aluminum alloy has yet been taken as a measure.
Problem to be Solved
However, the above-described one-way clutch has a problem in that load placed on the shaft member is concentrated at the shaft bores of the second rotation member in which both ends of the shaft member are held so that excessively large stress will be produced at the shaft bores.
In particular, if the second rotation member is made from aluminum alloy for weight reduction, the problem resulting from excessively large stress will outstandingly appear.
In view of the foregoing problem, a primary object of the present invention is to provide a belt-type one-way clutch which applies the principle of a two-shaft belt power transmission mechanism and which can increase the magnitude of transmittable torque while avoiding constraints placed due to the use of aluminum alloy as material of the second rotation member for its weight reduction by suppressing stress produced due to load of the shaft member being concentrated at shaft bores of the second rotation member which held respective ends of the shaft member in order to increase the magnitude of transmittable torque.
SUMMARY OF THE INVENTION
To solve the foregoing problem, the present invention takes the following solutions.
A first solution of the invention is a one-way clutch comprising: a first rotation member that has a working surface of circular cross section formed in an outer periphery thereof and is coupled to one of drive and driven sides; a second rotation member that is assembled with the first rotation member so as to rotate around the central axis of the working surface of the first rotation member and is coupled to the other of the drive and driven sides; a shaft member that is disposed radially outside of the working surface of the first rotation member to extend in parallel with the central axis of the working surface and is held at both ends thereof by the second rotation member; a rocking member that is placed radially outside of the working surface of the first rotation member, has a working surface of arcuate cross section formed in an outer periphery thereof and is supported for rocking motion on the shaft member; a friction member that is looped between both the working surfaces of the first rotation member and the rocking member to create two spans between the first rotation member and the rocking member; and a biasing member for tending to rotate the rocking member around the axis of the shaft member so that the rocking member presses one of the spans of the friction member, wherein both the ends of the shaft member are held by the second rotation member through respective support members that each cover side and end surfaces or at least the side surface of the corresponding end of the shaft member.
According to this solution, when the tension of the friction member is increased due to torque input to the one-way clutch, the load placed on the rocking member will be correspondingly increased and concentrated at holding portions of the second rotation member which hold both the ends of the shaft member. In this case, each of the support members, which is interposed between the corresponding end of the shaft member and the corresponding holding portion of the second rotation member, disperses the load so that stress produced within the holding portion of the second rotation member due to the load concentration can be suppressed to a low level. This avoids the situation that the stress as described above deforms the holding portion of the second rotation member to involve a mal-operation of the one-way clutch.
A second solution of the invention is based on the first solution, wherein the second rotation member is made from aluminum alloy. According to this solution, the second rotation member made from aluminum alloy can be reduced
Akahoshi Yoshihiro
Miyata Hirofumi
Nishikawa Shinichiro
Bando Chemical Industries Ltd.
Bonck Rodney H.
Cole Thomas W.
Nixon & Peabody LLP
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