Vehicle Drive Unit Quick Disconnect Mechanism
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Solution Overview
Problem
Existing hub-based disconnect mechanisms for vehicle power transmission units are not robust enough to operate effectively under high pressure conditions, such as when a vehicle is parked on a slope, and can be difficult to disengage, especially in harsh environments.
Innovation Solution
A disconnect mechanism that allows for quick disengagement by axial displacement of a handle and slower screw-disengagement by rotating the outer shaft, providing a mechanical advantage to overcome high frictional forces, and is intuitive and tool-free to operate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hub-based disconnect mechanism is used for quick disengagement, then ease of operation is improved, but reliability deteriorates under high pressure conditions
Solution Approach 1:
The mechanism provides two dynamic disengagement modes: a quick-disconnected mode for normal operation and a screw-disconnected mode for high-pressure conditions. The system adapts its disengagement characteristics based on the operational context, allowing the operator to select the appropriate mode for the current pressure conditions.
Solution Approach 2:
The mechanism changes the disengagement parameter from pure axial displacement (quick-disconnected) to threaded rotational movement (screw-disconnected). This parameter change allows the mechanism to overcome high frictional forces by converting linear force requirements into rotational torque, which can be applied more easily even under high pressure.
2Productivity
If axial displacement of the coupling shaft is used for quick disengagement, then productivity is improved, but force requirements worsen under high friction conditions
Solution Approach 1:
The system offers two dynamic disengagement paths: rapid axial displacement for normal conditions and controlled threaded withdrawal for high-force conditions. This dynamic approach allows the operator to maintain productivity by using the appropriate disengagement mode for the current operational context.
Solution Approach 2:
The screw-disconnected mode introduces a rotational dimension to the disengagement process. Instead of purely axial movement, the mechanism uses rotational torque applied through the handle to the threaded outer shaft, converting a high linear force requirement into a more manageable rotational force application.
3Reliability
If a threaded engagement is added for screw-disengagement, then reliability is improved under high pressure, but device complexity increases
Solution Approach 1:
The outer shaft serves multiple functions: it provides structural support, enables quick-disconnection through axial movement, and enables screw-disconnection through threaded engagement. This multi-functionality reduces the need for separate components for each disengagement mode, thereby limiting the increase in device complexity.
Solution Approach 2:
The mechanism merges the quick-disconnection and screw-disconnection functionalities into a single integrated system. The handle, outer shaft, and coupling gear work together to provide both disengagement modes, reducing overall system complexity compared to having separate mechanisms for each mode.
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
Enables reliable disengagement of the wheel drive from the vehicle power source even under pressure, maintaining operational simplicity and robustness across various conditions without requiring special tools.
Implementation Method 1
an outer shaft having a bore extending axially therethrough, the outer shaft defining a threaded engagement with the bore of the hub to axially move the outer shaft between an outer-shaft seated position and an outer-shaft withdrawn position
Implementation Method 2
A spring resiliently urges the disconnect shaft toward an engaged position, forming a splined engagement between the shaft and the sleeve
Implementation Method 3
This splined engagement transfers driving force from a hydraulic motor to the disconnect shaft via the sleeve
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A drive unit disconnect mechanism is operable to transmit or disconnect power from a vehicle power source to a driven unit, and can be disengaged by multiple methods depending on how much force is required to separate the internal components of the mechanism. In a first, relatively quicker method, a handle is pulled axially away from the hub to withdraw and internal gear from splined engagement with a corresponding driven gear. In a second, relatively slower method, the handle is rotated to threadably withdraw the entire disconnect mechanism from the hub, which in turn withdraws the internal gear from splined engagement with the driven gear. The quicker method is desirable in most instances, but the slower method allows disconnection of the driven unit from the vehicle power source when gear pressure prevents or impedes the quicker method.