Motor Unit Relay Box Layout for Compact EV Drive Casings
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Solution Overview
Problem
The existing drive devices for vehicles with integrated relay circuits face complexity in wiring, leading to larger casings due to the need to connect the relay circuit to both the inverter and the electric motor's neutral point, resulting in increased size and potential inefficiencies.
Innovation Solution
The drive device configuration includes a relay box mounted in a direction intersecting the rotation axis of the electric motor, with connecting holes between the gear casing and the relay box allowing the inverter and neutral point connection circuits to pass through, simplifying the structure and reducing casing size by integrating these circuits within the connecting hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the relay box is mounted in a direction intersecting the rotation axis of the electric motor, then the casing size is reduced, but the wiring complexity increases
Solution Approach 1:
The relay box is mounted in a direction intersecting the rotation axis of the electric motor (radial direction), changing the conventional axial mounting arrangement. This dimensional change allows the relay box to be positioned in the radial space between the motor casing and gear casing, effectively utilizing previously unused spatial dimensions to reduce overall casing size without extending the axial length.
Solution Approach 2:
The relay box is nested within the radial space formed by the motor casing and gear casing, effectively placing one component inside the spatial envelope created by other components. This nesting arrangement allows the relay box to share the radial space with the gear mechanism, reducing the overall casing volume without increasing axial length.
2Adaptability or versatility
If the relay circuit is connected to both the inverter and the electric motor's neutral point, then the charging function is improved, but the wiring complexity increases
Solution Approach 1:
The relay box serves multiple functions: it houses relays for charging control, provides mounting for the inverter, and facilitates electrical connections between the inverter, motor neutral point, and charging inlet. By consolidating these functions into a single component, the system achieves multi-functionality that reduces overall complexity despite the increased wiring requirements for dual connections.
3Stability of the object's composition
If the inverter casing is mounted to the gear casing in the first direction, then the structural stability is improved, but the casing size increases
Solution Approach 1:
Instead of mounting the inverter casing to the gear casing in the axial direction (first direction), the relay box is mounted in a direction intersecting the rotation axis (radial direction). This dimensional change allows the system to achieve structural stability through radial positioning while avoiding the volume increase that would result from axial extension.
Data Source
AI summary
A drive device disclosed herein may include: a motor casing housing the electric motor; a gear connected to the electric motor; a gear casing housing the gear; an inverter electrically connected to the electric motor; an inverter casing housing the inverter; and a relay box including at least one relay and having a relay circuit configured to connect a charging inlet of the vehicle to a neutral point of the electric motor and to the inverter. The motor casing, the gear casing, and the inverter casing may be arranged in this order along an axial direction extending parallel to a rotation axis of the electric motor. The relay box may be mounted at least to the gear casing in a first direction intersecting the rotation axis of the electric motor.