Machine element or mechanism – Control lever and linkage systems – Hand operated
Reexamination Certificate
2001-02-26
2004-01-27
Kim, Chong H. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Hand operated
C116S028100
Reexamination Certificate
active
06681652
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to a gear selection device for a variable gear mechanism, especially for a bicycle drive train.
Bicycles, both for everyday use and also for sporting use, are always equipped today with transmission devices, which offer a few or many gear ratios so that the rider can select the power and pedalling rate which are optimal for a particular state of physical fitness, for a particular speed, and for a particular terrain.
For this purpose, devices are provided for changing the gear ratio of the drive mechanism, whether this be a variable gear hub or a derailleur. These gear-change devices are mounted on the bicycle in the area where the force is transmitted to the rear wheel or in the area of the pedal drive mechanism.
For reasons of ergonomics, safety, and convenience, the actuating devices which the rider uses to select the desired gear ratio are often mounted today in the area of the handlebars or on the handlebars themselves. So-called “rotary” or “thumb” shifters, for example, are used for this purpose.
To arrive at a bicycle drive train which offers optimum ergonomics, it is desirable to have the largest possible number of different gear ratios. Modern variable-gear technology makes it possible in this respect to offer 3, 5, 7, 16, 24, or more ratios. The actuating devices for changing the gears on a bicycle must be highly sophisticated ergonomically in order to give the cyclist the ability effectively to monitor, to control, and to identify the selected gear ratio from among the large number of ratios available for selection.
Requirements on a modern actuating device for a variable gear mechanism of a bicycle include not only smooth operation, for example, but also the following items, which in no way represent an exhaustive list: an ergonomic location on the bicycle, a design compatible with hand and finger movements, the use of wear-resistant and simultaneously attractive and non-slip material for the surfaces for the actuating element, and the clear display of the currently selected gear ratio, which is especially important when a large number of gear ratios are available.
The requirements on the gear display comprise in addition the ability to provide the rider with an intuitive grasp of where the selected gear falls in relation to the complete range of ratios available for selection. Thus it is necessary not only for the gear actually engaged to be displayed but also for at least the immediately adjacent gears and the available range of selectable ratios extending from the selected ratio to the upper and/or lower end of the range to be displayed as well.
In many cases, this task is accomplished today by, for example, a raised marking or a colored mark, which is provided on the manually movable actuating elements of the gear selection device. With this system, the current position of the marking shows the rider which gear is engaged by the relationship between the marking and a gear display scale, which is in a fixed position relative to the housing of the actuating device.
The disadvantage of these known display units on gear selection devices for the variable gear mechanisms of bicycles, however, especially in the increasingly common case where the mechanism offers a large number of gear ratios, is that the marking or the indicator element which tells the rider which gear has been engaged is not always located within the viewing angle of the rider which would be best for optimum and ergonomic readability. The reason for this is that, because of the large number of gears, the actuating devices must travel long distances.
The disadvantage described above, namely, the difficulty of reading at least certain parts of the gear display device, pertains especially but not exclusively to the display device of the so-called rotary grip shifter, which is standard equipment on many bicycles for everyday and sporting use. In rotary grip shifters of this type, at least a part of the hand grip of the bicycle handlebar is suitably designed so that it can be rotated essentially around the axis of the end of the handlebar. Thus, by making defined rotational movements with the hand or wrist, the rider can engage the desired gear through the intermediate action of a suitable control device and a transfer device for transferring the control movement to the variable gear mechanism.
In order to ensure that the gear selection device will operate smoothly, that the correct position can be found when moving the transmission device from one position to another, and that the ergonomic aspects are respected, the total angle of rotation of the actuating element, especially in the case of the gearshift mechanisms with a large number of different ratios, is often so large today that the marking or the indicator element can move so far in an extreme case that it is no longer within the viewing angle of the rider or at least moves to an unfavorable viewing angle at one or both ends of the gear ratio scale, this favorability or lack thereof also being a function of the seating position of the rider and his line of sight.
Display devices for the shifters of variable gear mechanisms on bicycles are known in which the currently engaged gear is represented to the rider in graphic or numerical form in a viewing window, which is stationary in relationship to the shifter. Display devices of this type avoid the disadvantage described above, that is, the difficulty of reading parts of the scale of gear ratios, but they do not meet the challenge, arising from the requirements of visual ergonomics, of presenting in visual form not only a display simply of the selected gear ratio but also a display of the relative position of the selected gear ratio within the complete range of possible ratios (compare the differences in properties between an analog display and a digital display of measurement values or time).
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide a gear selection device which meets both the requirement of clear display of the gear engaged at the time in question and the challenge of displaying the entire range of available gears, both in absolute terms and also in relationship to the engaged gear, even when there is a large number of different gear ratios and therefore a large total actuating angle of the actuating device, and by means of which it is also possible to preserve the maximum scale angle or display arc required for reasons of visual ergonomics.
According to the invention, this gear selection device has a transmission device, which transmits the angular movements of the actuating device (or control device driven by the actuating device) to the display in such a way that the arc through which the indicator element or the marking on the display device delineates or passes through in each case is smaller than the arc which the actuating element of the actuating device passes through at the same time. This means, even if, for construction reasons, the actuating device has a very large total actuating angle, the display device can still be designed in such a way that the display angle or the length of the arc of the display device on which the display scale of the complete range of gear ratios is to appear can be limited to a certain size for ergonomic reasons.
In accordance with an especially advantageous embodiment of the gear selection device, the transmission device located between the actuating device or the control device and the display device is designed as a gear, especially as a gear wheel mechanism. Because of the form-locking connection of the gear wheel mechanism, it is possible with this design to obtain the advantage of a uniform transmission ratio between the control device and the display device and also to guarantee that, in every gear which is engaged, the control device and the display will always be in the same position relative to each other, a condition which is required so that the indication of the display and the gear ratio actually selected at the time in question will always correlate
Assel Martin
Auer Marcus
Kim Chong H.
Milosevic Milan
SRAM Deutschland GmbH
Wunderlich Lisa
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