Patent Application
20080047386
The above mentioned and other features of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. Although the exemplification set out herein illustrates embodiments of the invention, in several forms, the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention to the precise forms disclosed.
An automotive foot pedal assembly 20 in accordance with the present invention is illustrated in
As best seen in
Although the illustrated embodiment shows hub 28 on first member 22 and sleeve 34 on second member 32, other configurations are also possible. For example, hub 28 could be on second member 32 and sleeve 34 could be located on first member 22. Alternatively, a separate sleeve rotatable on pivot stud 26 could extend through hubs on each of first and second members 22, 32 and two separate tolerance rings could be used to connect the separate sleeve to each of first and second members 22, 32.
Tolerance rings generally take the form of a linear corrugated metal strip that has been bent into a substantially circular ring-shape and is fitted between two mechanical parts in an interference fit to thereby secure the two parts together. Tolerance rings transfer torques between the two parts being secured by frictional engagement unless the torque exceeds a threshold value dependent upon the design of the parts and the tolerance ring at which point one of the parts will slip relative to the ring and whereby the two parts will slip relative to each other. Tolerance rings are well known to those having ordinary skill in the art and are often used to hold a bearing on a shaft or secure a bearing in a housing.
Turning to
As can also be seen in
During normal operation of the vehicle, the operator applies a force to foot pedal 24 to activate the brakes. As this force is applied to foot pedal 24, first member 22 is rotated about pivot stud 26. Frictional coupling 48, which is formed by tolerance ring 36 and its interface with first and second members 22, 32 in the embodiment illustrated in
The first member defines a first pivotal range of operation during normal operation as schematically depicted by range 50 in
When a force exceeding a threshold value of frictional coupling 48 is applied to foot pedal 24, frictional coupling 48 permits slipping, i.e., relative rotational movement between first and second members 22, 32. In a collision where a forward traveling vehicle is brought to a sudden stop while the operator is applying the brakes, a large force exceeding the threshold value of frictional coupling 48 may be applied to foot pedal 24. In such an event, the slippage at frictional coupling 48 will result in first member 22 rotating towards position 54 while second member 32 remains stationary. The frictional resistance of coupling 48 to this relative movement partially dissipates the force that is being applied to foot pedal 24. This dissipation of force enhances the safety of the operator of the vehicle because some of the dissipated force will have been the result of the forward momentum of the operator of the vehicle. Frictional coupling 48 also enhances the safety of the operator because, prior to first member 22 bearing against a structural feature of the vehicle, the maximum force that foot pedal 24 can apply to resist the forward motion of the operator is determined by the threshold value at which frictional coupling 48 begins to slip.
After the force being applied to foot pedal 24 is diminished below a second value, frictional coupling 48 will re-couple first and second members 22, 32 together. Generally, the second force value at which this re-coupling takes place will be less than the value of the threshold value at which relative movement between first and second members 22, 32 is initiated. Because some relative movement of first and second members 22, 32 has taken place, when frictional coupling 48 re-couples the first and second members 22, 32, members 22, 32 will be in a post-event configuration that differs from the original configuration of members 22, 32.
In this post-event configuration, first member 22 will not be biased forward to position 52, instead first member will only be biased forward to an intermediate position 58 which is dependent upon the amount of slippage that occurred prior to the re-coupling of first and second members 22, 32. In
It is noted that, in the post-event configuration, when first member 22 returns to intermediate position 58, second member 32 will be in the position in which second member 32 is shown in dashed lines in
As will be understood from the description set forth above, the operation of the frictional coupling 48 is independent of relative movement between frictional coupling 48 and automotive structure 46. In other words, frictional coupling 46 does not require the deformation of automotive structure 46 in a collision to bring frictional coupling 48 into contact, or out of engagement, with the surrounding automotive structure 46 to permit the relative movement of first and second members 22, 32. Instead, it is the magnitude of the force being applied to the frictional coupling 48 via pedal 24 that determines whether or not such relative movement will take place.
Another embodiment of a foot pedal assembly is shown in
First member 22a defines a first frictional engagement surface 62 while second member 32a defines a second frictional engagement surface 64. Biasing member 66, which takes the form of a helical compression spring in the illustrated embodiment, biases surfaces 62, 64 into engagement. The major portions of first and second frictional engagement surfaces 62, 64 are disposed substantially perpendicular to common axis 27a and biasing member 66 disposed on pivot stud 26a exerts a force parallel to common axis 27a to forcibly engage surfaces 62, 64.
Various alternative designs of frictional engagement surfaces 62, 64 may also be employed with the present invention. Additionally, an intermediate separate part positioned between surfaces 62, 64 could be used to engage surfaces 62, 64 in the operable coupling of first and second members 22a, 32a whereby surfaces 62, 64 would be indirectly engaged through such an intermediate separate part.
In the illustrated embodiment, one end of spring 66 bears against an end cap 68 with a retaining lip 69 along its outer perimeter. End cap 68 thereby retains spring 66 on pivot stud 26a and bears against pivot head 78. The end of spring 66 opposite end cap 68 is seated in circular recess 67 located on an end wall 72 on first member 22a. End wall 72 extends radially inwardly and helps to retain first member 22a in a centered position as it rotates about common axis 27a.
The action of spring 66 biases first engagement surface 62 located on a radial flange 60 on first member 22a into engagement with second frictional engagement surface 64 second member 32a. Second member 32a has a circular flange 74 opposite surface 64 that bears against pivot head 76 on pivot stud 26a.
As best seen in
Similar to assembly 20, assembly 20a illustrated in
As illustrated in
When the threshold force value is exceeded, shear pin 70 is severed at the interface between hub 28a and sleeve 34a resulting in the relative motion of first and second members 22a and 32a. After shear pin 70 has been severed, frictional coupling 48a depends upon the frictional engagement of surfaces 62, 64 to re-couple first and second members 22a, 32a together. Thus, by including a shear pin 70 in assembly 20a, the magnitude of the threshold value of the force applied to foot pedal 24 required to first initiate relative movement between first and second members 22a, 32a is increased but the operation of assembly 20a is otherwise unaffected.
While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles.
