Actuator Piston Locking for Parking Brake Reliability
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Solution Overview
Problem
Existing actuating devices for parking locks in automatic transmissions lack reliable mechanisms to prevent unintentional release due to hydraulic system failures or errors, particularly in shift-by-wire systems.
Innovation Solution
The actuating device incorporates a sleeve-shaped piston with an integrated electromagnet and guide sleeve, featuring radially extendable blocking elements and a helical compression spring, which secures the piston in both engaged and disengaged positions, ensuring the parking lock remains locked against unintentional release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the electromagnet and guide sleeve are integrated within the piston structure, then the overall length of the actuator is reduced, but the structural complexity increases
Solution Approach 1:
The invention merges multiple components (electromagnet, guide sleeve, locking element) into a single integrated piston structure. The electromagnet is positioned within the piston, and the guide sleeve is integrated with the piston body, creating a compact assembly. This merging reduces the overall length of the actuator while consolidating functions into fewer discrete parts.
Solution Approach 2:
The invention employs a nested arrangement where the electromagnet is positioned within the piston structure, and the guide sleeve contains the locking element. The locking element can move radially within the guide sleeve, which itself is integrated into the piston. This nesting of components within each other achieves space efficiency and reduces the overall actuator length.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the reliability of the parking lock by maintaining a secure engagement state even in case of hydraulic system failures, reducing the overall length of the actuating device while ensuring effective blocking functions and easy assembly.
Implementation Method 1
an electromagnet (22) which actuates the locking device (20)
Implementation Method 2
A plunger of the electromagnet acts on the pressure piece (34) of the locking device (20), which is biased against the plunger by a helical compression spring (38)
Data Source
Figure 1
AI summary
An actuator for activating a parking lock, in particular for automatic transmissions in motor vehicles, having a piston which is guided in a cylinder and which activates a ratchet for a parking lock wheel in the transmission by means of an actuating rod, wherein the piston disengages the parking lock counter to the force of an integrated prestressing spring by being acting on hydraulically, and in the pressureless state the prestressing spring engages the parking lock, and wherein in addition a locking device which can be activated electromagnetically and which can secure the piston in the disengaged position in a positively locking fashion is provided, said locking device securing the piston relative to a guide sleeve attached to the cylinder, by means of locking elements which can be extended radially. In order to provide improved system protection it is proposed that the piston (16) can also be secured in a positively locking fashion by means of the locking device (20) in the position (P) corresponding to the engaged state of the parking lock.