Vehicle Drive Unit Partition-Wall Pump Layout to Prevent Oil Leakage

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Solution Overview

Problem

The existing vehicle drive devices have a complex configuration of the hydraulic pump due to the need for sealing members and relief valves to prevent oil leakage, which complicates the system.

Innovation Solution

The pump chamber of the hydraulic pump is integrated into the partition wall of the case, dividing it into two housing chambers, allowing oil to flow into one of these chambers without leaking out, eliminating the need for sealing members and relief valves.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the hydraulic pump is disposed outside the case with a separate pump cover joined to the side wall portion, then the pump can be independently maintained and assembled, but the configuration becomes complicated requiring sealing members and relief valves to prevent oil leakage

Engineering Contradiction:
ImproveIndependent assembly and maintenance of hydraulic pumpVSAvoidConfiguration complexity of hydraulic pump
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the hydraulic pump with the case structure by forming the pump chamber directly within the case body using a recessed portion, eliminating the need for a separate pump cover and its associated sealing components. This integration reduces device complexity while maintaining the pump's functional independence through internal chamber design.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If sealing members and relief valves are added to prevent oil leakage from the pump chamber, then oil leakage is prevented, but the hydraulic pump configuration becomes more complicated

Engineering Contradiction:
ImproveOil leakage preventionVSAvoidHydraulic pump component count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent converts the potential harmful effect of oil leakage into a beneficial contained system by designing the pump chamber as a recessed portion within the case. The case structure itself serves as the containment boundary, eliminating the need for additional sealing members and relief valves, thereby preventing oil leakage without increasing component count.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If the pump chamber is formed between the side wall portion and pump cover, then the pump structure is established, but sealing members are required to prevent oil from leaking to the outside of the case

Engineering Contradiction:
ImprovePump chamber formationVSAvoidOil leakage to outside of case
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent combines the pump chamber formation directly into the case structure by creating a recessed portion in the case body. This integration eliminates the boundary between the pump chamber and case, removing the need for sealing members at the interface and preventing oil leakage to the outside of the case.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4167444B1Vehicle drive device
Publication Date: 2025.07.02 AISIN CORP
  • EP4167444B1 patent drawingFigure 1
  • EP4167444B1 patent drawingFigure 2
  • EP4167444B1 patent drawingFigure 3

AI summary

A vehicle drive device (100) includes: a rotating electrical machine (MG) that functions as a driving force source for wheels (W); an input member (1) drivingly connected to the rotating electrical machine (MG); a pair of output members (4) each drivingly connected to the wheel (W); a differential gear mechanism (3) that distributes rotation transmitted from the rotating electrical machine (MG) to the pair of output members (4); a transmission gear mechanism (2) that drivingly connects the input member (1) and the differential gear mechanism (3); a hydraulic pump (6) that includes a pump rotor (61) and a pump chamber (62) housing the pump rotor (61) and that supplies oil to at least the rotating electrical machine (MG); and a case (9). The case (9) includes a partition portion (91) that separates in an axial direction (L) a first housing chamber (A1) housing the rotating electrical machine (MG) and a second housing chamber (A2) housing the transmission gear mechanism (2) and the differential gear mechanism (3). The pump chamber (62) is formed in the partition wall (91) so as to be located between the first housing chamber (A1) and the second housing chamber (A2) in the axial direction (L).