Coupling Sleeve Torque Control for Vehicle Drive Resonance
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Solution Overview
Problem
The torsional resonance frequency of a vehicle's drive system often coincides with the unsprung resonance frequency, leading to excessive torque fluctuations when traveling on irregular roads, which can degrade vehicle performance and comfort.
Innovation Solution
A drive unit with a coupling sleeve that varies the engagement lengths between motor-side and gear-side shafts, adjustable via an actuator, to alter the torsional resonance frequency and prevent coincident resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the torsional resonance frequency of the drive system coincides with the unsprung resonance frequency, then the drive system structure is simple, but excessive torque is generated when traveling on irregular roads
Solution Approach 1:
The coupling sleeve is made movable in the axial direction to dynamically adjust the engagement lengths between splines. This dynamic adjustment changes the torsional rigidity of the drive system, thereby varying the torsional resonance frequency to avoid coincidence with the unsprung resonance frequency, suppressing excessive torque generation while maintaining a relatively simple overall structure
Solution Approach 2:
The invention changes the torsional rigidity parameter of the drive system by varying the engagement lengths of the coupling sleeve. By adjusting the axial position of the coupling sleeve, the engagement lengths between the first and second splines change, which directly alters the torsional resonance frequency to prevent harmful resonance coincidence
2Object-affected harmful factors
If the coupling sleeve is made movable to adjust torsional resonance frequency, then excessive torque is suppressed, but the device complexity increases
Solution Approach 1:
The coupling sleeve is disposed to extend from the motor-side shaft to the gear-side shaft, with splines nested on the inner peripheral surface engaging with splines on the outer peripheral surfaces of both shafts. This nested configuration allows the coupling sleeve to function as both a torque transmitting element and a variable engagement mechanism, achieving frequency adjustment without adding separate complex components
Solution Approach 2:
The coupling sleeve serves multiple functions: it transmits torque from the motor-side shaft to the gear-side shaft, adjusts the torsional resonance frequency by varying engagement lengths, and can be controlled by an actuator. This multi-functionality reduces the need for additional dedicated components for frequency adjustment
3Speed
If the engagement lengths are varied to change torsional rigidity, then the torsional resonance frequency is adjusted, but the manufacturing precision requirements increase
Solution Approach 1:
The coupling sleeve divides the torque transmission path into two separate engagement segments: one with the motor-side shaft and another with the gear-side shaft. By segmenting the engagement, the invention allows independent variation of engagement lengths while maintaining reliable torque transmission, reducing the overall precision requirements compared to a single rigid connection
Data Source
AI summary
A drive unit mounted on a vehicle includes: a motor; a motor-side shaft having a first spline on an outer peripheral surface thereof and rotated by torque from the motor; a gear-side shaft having a second spline on the outer peripheral surface thereof and disposed coaxially with the motor-side shaft; and a coupling sleeve disposed from the motor-side shaft to the gear-side shaft and having a third spline on the inner peripheral surface thereof that engages with the first spline and the second spline. The coupling sleeve is configured to be movable along the axial direction, and at least one of a first engagement length in which the third spline engages the first spline and a second engagement length in which the third spline engages the second spline varies according to an axial position of the coupling sleeve.