Integrated Power Shaft Structure for Concentric Electric Drive Gears
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Solution Overview
Problem
Existing electric drive assemblies face complications in torque transmission due to separate design of motor and reducer shafts, leading to increased axial size, poor concentricity, and poor NVH performance, with high manufacturing costs for improved precision.
Innovation Solution
A power shaft structure integrates the motor and reducer shafts as a single main shaft with axially extending flanges and bushings for radial positioning, ensuring concentricity and stability through transition or interference fits and bearings, reducing axial size and improving dynamic balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a motor and a generator are integrated into a single electric drive assembly, then space saving and integration benefits are achieved, but the power shaft becomes susceptible to corrosion from coolant leakage
Solution Approach 1:
A seal ring is introduced as an intermediary component between the coolant passage and the power shaft. The seal ring prevents coolant from reaching and corroding the power shaft, while allowing the integrated motor-generator design to maintain its compact form factor.
Solution Approach 2:
The seal ring is installed in advance on the power shaft to prevent coolant corrosion before any leakage can occur. This proactive protection allows the integrated design to proceed without compromising the power shaft's durability.
2Ease of manufacture
If the power shaft is made longer to extend the generator output, then more space is available for generator winding layout, but the shaft becomes more susceptible to corrosion from coolant leakage
Solution Approach 1:
The seal ring serves as a protective intermediary that extends along the power shaft, creating a barrier that prevents coolant from corroding the shaft surface. This allows the shaft to be made longer for winding space without proportionally increasing corrosion risk.
3Area of moving object
If the power shaft surface is increased in area, then more space is available for generator windings, but the surface area exposed to coolant corrosion increases
Solution Approach 1:
The seal ring creates a protective barrier that covers the power shaft surface, allowing the shaft area to be increased for winding space while the seal ring prevents coolant from contacting and corroding the expanded surface area.
Data Source
Figure 1~2
Figure 3~4
AI summary
A power shaft structure of an electric drive assembly is disclosed. The power shaft structure comprises a main shaft (1), a right end of the main shaft (1) is located inside a motor (2) and fixedly connected to a rotor (3) of the motor (2), and a left end of the main shaft (1) is located inside a reducer (4) and fixedly connected to a driving gear (5) and a parking gear (6) of the reducer (4). At least one side of the driving gear (5) is provided with an axially extending flange, and at least one side of the parking gear (6) is provided with an axially extending flange. A bushing (8) is provided between an inner hole of one flange at one side of the driving gear (5) and the main shaft (1) as weel as between an inner hole of one flange at one side of the parking gear (6) and the main shaft (1) for radial positioning of the driving gear (5) and the parking gear (6), so that the driving gear (5), the parking gear (6), and the main shaft (1) are on the same axis, thereby improving the stability and NVH performance of the electric drive assembly.