Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
2001-02-13
2003-12-09
Joyce, William C (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
C074S473280, C074S527000
Reexamination Certificate
active
06658959
ABSTRACT:
BACKGROUND
The invention involves a shifting device on a gearbox, with a transmission component for transmitting the shifting movements associated with the changing of gears, where this transmission component can either be pushed in a lengthwise direction, or can be pivoted around its axis, which axis is situated at the midpoint in the path of longitudinal movement, as, for example, a selector shaft, and at least one stoppage point, at which point the transmission component at least is moveable by means of pushing in a lengthwise fashion, or through being pivoted around its longitudinal centerline into at least one stop position in the speed change gearbox, and—in at least one stop position—travels against the limit stop.
If components installed in such a way as to be susceptible to longitudinal movement, and/or rotary movement, as well as swivel movement are restricted by means of mechanical limit stops, and if assemblies in their longitudinal or swing movement are similarly restricted, then the result is not only high levels of stress and strain on the construction components, but also noises are produced when the moved component make contact with the limit stop. The selector shafts in the speed change gearboxes of motor vehicles, for example, are components of this sort. The selector shafts are moved in a longitudinal direction for elective shifting movements, or pivoted and transferred around a pivot axis by means of one or several transmission components, for example shifting movements on a selector shaft, a selector fork or on a gear shift lever. The pathway of the selector shaft must be restricted for the elective and/or shifting movements. The selector shafts are moved into a stop position in accordance with the transmitting of an elective movement by means of the shifting movement, in which the chosen path is located. Also, a selected position can finish at the end of a channel in a stop position. The shifting and elective pathway of selector shafts in the stop positions is often restricted by means of limit stops. The selector shafts or selector rails can attach in a secure position in the housing or to a shifting gate in that way the restriction contour of a casing, or of a shift gate serves as a limit stop as well as a restriction on the pathway. The pathway of a shaft in an axial direction and/or in a pivot direction can be definitely fixed by means of a pin that travels along in the shifting gate and that pushes into the end positions at the contour of the shifting gate profile. The sequence of the shifting processes frequently produces a sudden braking of the transmission component in the shifting device at the limit stops. Vibrations are thus generated and along with consequent sounds.
In the past, various types of damping elements were utilized for the purpose of avoiding aforementioned undesirable sounds in shifting devices. For example, WO 90/03523 describes a selector shaft with a damping arrangement, in which air is used as the specific means of achieving the desired damping effect. A gear shift lever is set in motion by means of the selector shaft, while the selector shaft itself is shifted in an axial direction into different end positions by a piston that is loaded by means of compressed air. On reaching the end positions, the piston plunges into a counter pressure chamber area. At that point, the air that is impinged upon by the axially shifted pistons escapes slowly through a throttling opening. In this way, mechanical knocking is prevented. The antecedently mentioned selector shaft, and consequently also the gear shift levers are halted in the end positions by means of stop elements. The stop elements arrest the selector shaft in the end positions, by engaging with a spring-loaded ball or a pin into an indentation in the selector shaft. The hollows are restricted in a longitudinal direction, by means of flanks that are formed in a ramp-like fashion. When the selector shaft is axially shifted out of one of the end positions into another end position, the ball at one of the flanks rises, moves along a track, and travels down another flank into another indentation. Devices that are damped by means of compressed air are relatively expensive to produce, and they are also costly due to the multiplicity of individual parts that are used, and require as a precondition of this the presence of a supply source of compressed air, as well as the existence of additional components that work together with this compressed air. Damping components of this kind are put in place for the most part only on the speed change gearboxes of utility vehicles that are activated or supported by compressed air. In particular, in hand shifted transmissions in personal motor vehicles, therefore mechanical limit stops cannot be abandoned. Between the limit stop and the part to be stopped a damping material such as a rubber or plastic is used. The rubber, as well as the plastic prevents, or in any case decreases, the mechanically induced vibrations that lead to the sounds.
Shifting speeds using a selector shaft that is susceptible to being shifted in a longitudinal fashion as well as in a pivoting manner normally takes place in two steps. In the first step, for purposes of choosing, an axial shifting of the selector shaft into an end position is envisioned. In this way, a shift finger that is connected to the selector shaft, or some similar component thus connected, is brought into its end position. In the second step, it is pivotably shifted from this end position by pivoting of the selector shaft into the speed, by means of the shift finger and other components. Conversely, the first step can also be carried out by means of a pivoting movement, and in the second step the shifting of a speed can be achieved by a longitudinal movement. When, in the first step, the selector shaft is brought axially into one of the end positions, it frequently knocks against a limit stop axially in the process. Under certain circumstances, a damping component, of rubber or plastic, is installed in place between the selector shaft for reasons that are well known. When the selector shaft is shifted during the second step of the switching process, the selector shaft rubs at the damping component. Especially when the damping component is manufactured from a rubber material, the selector shaft must be operated at an increased energy level, due the friction forces exerted. Frequently, the operator of the device senses this effect on the basis of uneven, and consequently unacceptably inconsistent shifting forces.
With selector shafts, in which the restriction contour of a crank serves simultaneously as a limit stop, and as a means of restricting the pathway of the selector shaft, no damping mechanisms are pivoted as components. Here frequently one simply accepts the mechanical noise connected with the knocking.
A selector shaft which defines the genus of this type is described in DE 198 05 924 A1. The selector shaft bears a catch sheath, as well as a shift finger, and is mounted for axial movement. On the catch sheath, a catch profile as well as a shifting gate are formed. A stop element that is secured in position relative to the longitudinal centerline works into the catch profile. By means of the catch profile and the stop element, the selector shaft is held either in a neutral position or in one of several end positions. The stop element engages with indentations. The catch profile is formed in such a way that three elongated grooves proceed in longitudinal direction on the exterior surface of the catch sheath, that are adjoined to one another circumferentially. In its longitudinal course in each direction, the base of the longitudinally extended groove rises away from an indentation to a relatively flat plane, in either a ramp-like fashion or in curved formation. Upon the application of force to the selector shaft—which causes longitudinal movements in one or another direction—the vertically spring-loaded ball which acts on the longitudinal centerline of the selector shaft, rises up out of the indentatio
Grieshammer Andreas
Landa Boris
Schübel Rainer
Steinberger Wolfgang
Wildeshaus Walter
INA - Schaeffler KG
Joyce William C
Volpe and Koenig P.C.
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