Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
1999-07-08
2001-09-11
Footland, Lenard A. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
Reexamination Certificate
active
06286384
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the priority of German Patent Application Serial No. 198 31 066.8, filed Jul. 10, 1998, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates, in general, to a mechanically operated change-speed gearbox for use in motor vehicles, and more particularly to a shift control apparatus for a change-speed gearbox, including a locking mechanism for preventing a misshift between a forward gear and a reverse gear when actuating a gear selector lever which is operatively connected to a selector shaft.
Locking mechanisms, also known as reverse gear lock-out mechanism, are used in gearboxes to prevent a shift-through from a forward gear into reverse gear, when these gears are positioned in a same linear shifting lane. Erroneous shifting into reverse gear, that may occur if the selector lever were to be moved directly from one forward gear to the reverse gear, are thereby prevented and the gears are protected from damage so that serious damage of the shift control mechanism is avoided. Typically, the reverse gear lock-out mechanism is so structured that the selector lever must be first moved into neutral before clearing the shifting lane to the reverse gear and allowing a shift into reverse.
German Pat. No. DE-C 36 01 954 describes a reverse gear lock-out mechanism having a shift control mechanism with a selector shaft which includes a shifter finger for interaction with a gear shifting gate that is mounted to the housing wall of the gearbox. The shifting gate includes the shifting lane for the gear selection and has a prolongation which accommodates a locking mechanism in communication with a second shifter finger. The locking mechanism includes a plate which is swingably mounted to the shifting gate and held in neutral by a leg spring and swingable in two directions. The plate has a top side formed with a locking cam with a so-called arched catch, for cooperation with the second shifter finger. When changing from the fifth gear to the fourth gear, the second shifter finger strikes against the locking cam to thereby prevent a shift-through along a straight line into the reverse gear which is positioned in the same shifting lane as the fifth gear. The restraining action realizes a diverting of the shifter finger into the neighboring shifting lane. This conventional reverse gear lock-out mechanism suffers the drawback that a great number of components and a substantial space for installation are required because the shifting gate, guiding the shifter fingers which are radially aligned with respect to the selector shaft, is arranged parallel and offset to the selector shaft. As a consequence of the interaction between the shifter fingers and the shifting gate, the manufacture of the individual components as well as the installation and adjustment of the conventional locking mechanism demands high precision.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an improved shift control apparatus for use in motor vehicles, obviating the afore-stated drawbacks.
In particular, it is an object of the present invention to provide an improved shift control apparatus with a locking mechanism for preventing inadvertent shifting into reverse gear, which locking mechanism is simple in structure and cost-efficient, and yet is reliable in operation and enhances the shifting comfort.
These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a selector shaft which is axially slidably and rotatably supported by a housing and operatively connected to a gear selector lever for preselecting a shifting lane through axial displacement and shift into a selected gear through rotation, a shifter finger secured to the selector shaft and engaging slidable shifter forks or shifter bars, and a locking mechanism for preventing a misshift between a reverse gear and a forward gear in a same shifting lane, with the locking mechanism including a transmission element mounted in fixed rotative engagement to the selector shaft and having a flanged edge, and a restraining member rotatable and axially moveable in parallel relationship to the selector shaft, whereby the restraining member has a locking surface forming a deflector ramp for support of the flanged edge of the transmission element.
The provision of the deflector ramp improves the shifting comfort as the pure locking action is deviated into a deflecting motion. During change to a different gear between two gears in a shifting lane, i.e. from forward gear to reverse gear, the selector shaft executes a rotational movement. At the same time, the deflector ramp of the restraining member triggers a force component in axial direction in synchronism to the rotational movement. Therefore, this gear change results in a smooth deflection of the transmission element into neutral, thereby enhancing the shift feel. This deflection leads to a reduced strain of all components that make up the locking system.
An effective locking surface can be established when the deflector ramp extends at an angle from about 55° to 60° with respect to a longitudinal bore or guide bore of the restraining member, whereby the deflector ramp, when installed, is inclined with respect to the transmission element. Certainly, the deflector ramp may be configured in different ways, without departing from the spirit of the present invention. Suitably, the deflector ramp is designed as a slanted straight line. Alternatively, the deflector ramp may also exhibit a convex or concave pattern to influence the shift feel. These types of deflector ramps realize a planned accelerated or delayed deflection of the transmission element and of the shifting components interconnected therewith.
According to another feature of the present invention, the restraining member may be adjustable with respect to the transmission element. Adjustability of the restraining member permits a compensation of encountered tolerances of all components making up the locking mechanism as well as of the transmission element, selector shaft and restraining member. Thus, the shifting comfort is further enhanced.
The adjustment of the restraining member can be implemented in several ways. In one embodiment, adjustment of the restraining member is realized by inserting into the housing an adjustment screw, for example a stud screw, upon which the restraining member directly rests. After completing the adjustment, the adjustment screw can be secured, for example, by a retainer element, to inhibit a self-inflicted repositioning of the adjustment screw. Another embodiment includes the provision of a key pin by which the position of the restraining member can be adjusted. The key pin is suitably formed with a cylindrical section for insertion in a bore which is provided in the housing in axis-parallel disposition to the receiving bore of the restraining member, with the key pin being pushed into the housing until its wedge surface interacts with a corresponding contact surface of the restraining member. Once adjustment of the restraining member has been carried out, the key pin is suitably fixed in place in the housing.
According to another feature of the present invention, the restraining member may have a tubular section which is guided on an axle fitted in the housing. In this manner, the restraining member is securely guided and prevented from tilting. On one end, the tubular section of the restraining member may be provided with a radial first guide segment which forms the deflector ramp and interacts with the flanged edge of the transmission element. The tubular section of the restraining member may further be provided with a second guide segment which extends angularly offset to the first guide segment and also interacts with the inside wall of the housing.
According to another feature of the present invention, the flanged edge of the transmission element may be provided with a guide surface which corresponds
Feiereisen Henry M.
Footland Lenard A.
Ina Walzlager Schaeffler OHG
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