Transmission Parking Lock Ramp Gradient Design

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Solution Overview

Problem

Existing parking locks for automatic transmissions experience high loads at contact points between actuating elements and ramp surfaces, making movement sequences difficult and compromising component functionality.

Innovation Solution

A parking lock design featuring a ramp with a varying gradient transverse to the actuation direction, allowing the actuating element to contact the ramp at multiple points or along a line, reducing loads on both the pawl and housing, and incorporating a helicoidal ramp surface for linear support independent of pivot position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a constant ramp gradient is used in the actuation direction, then the movement sequence of the cam element and pawl is uniform and simple, but high loads occur at the contact points between the actuating element and ramp surface

Engineering Contradiction:

Improvemovement sequence simplicityVSAvoidload at contact points

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The ramp gradient is varied locally in the transverse direction to distribute the contact load. Different sections of the ramp width have different gradient values, creating a gradient distribution that spreads the force from the actuating element across multiple contact points rather than concentrating it at a single point.

Inventive Principle:

Principle #3Local quality

2Device complexity

If the actuating element contacts the ramp at one point, then the structure is simple, but the load at that point becomes excessively high

Engineering Contradiction:

Improveramp structure simplicityVSAvoidload at contact point

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The ramp structure maintains overall simplicity while introducing local gradient variation. The gradient varies transversely across the ramp width, transforming a single-point contact into multi-point or line contact, thereby distributing the force without complicating the fundamental ramp structure.

Inventive Principle:

Principle #3Local quality

3Force

If a varying ramp gradient is used transversely, then the load on the pawl and actuating element is reduced, but the ramp structure becomes more complex

Engineering Contradiction:

Improveload distributionVSAvoidramp gradient structure

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The ramp gradient parameter is changed in the transverse direction to achieve load distribution. By varying the gradient value across the width of the ramp, the contact force is distributed over multiple points or a line, reducing peak loads while maintaining a relatively simple overall ramp structure.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8225921B2Parking lock for a transmission

Publication Date: 2012.07.24 ZF FRIEDRICHSHAFEN AG

AI summary

A transmission parking lock with a ramp (10) for pressing against an actuating element. The ramp (10) defines an actuation direction (11) in which the actuating element can be moved and the ramp (10) has a ramp gradient in the actuation direction (11). The ramp gradient varies transversely with respect to the actuation direction (11) such that the load between a pawl (1) and of the actuating element can be reduced.