Hybrid Power Transmission Crankcase Layout for Compact Lubrication

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Solution Overview

Problem

Existing hybrid vehicle power transmission systems face challenges in size increase and complex lubrication due to the placement of power transmission mechanisms around peripheral components, leading to increased overall size and complexity.

Innovation Solution

A compact power transmission system design where the power transmission mechanism is fully accommodated within a crankcase, with a main chamber for the engine and drive motor components and a subsidiary chamber for the main clutch, allowing for efficient lubrication and reduced vehicle width, using a divided cover structure to minimize noise and size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the power transmission mechanism is disposed around peripheral components in the power transmission route, then the power transmission can be achieved, but the overall size of the power system is increased

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidoverall size of power system
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The patent merges the power transmission mechanism with the crankcase by integrating it into the subsidiary chamber. The chain case, which houses the power transmission mechanism, is formed as an integrated part of the crankcase structure, eliminating the need for separate housing and reducing overall system size while maintaining power transmission functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The power transmission mechanism is nested within the subsidiary chamber of the crankcase. The chain case is positioned within the crankcase structure, and the power transmission components are contained within the chain case, creating a nested arrangement that optimizes space utilization and reduces the overall footprint of the power system.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of manufacture

If the power transmission mechanism is configured in a complicated fashion, then the power transmission can be achieved, but the structure for lubrication of the power transmission mechanism is also complicated

Engineering Contradiction:
Improvepower transmission capabilityVSAvoidlubrication structure complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The lubrication system is merged with the engine's existing lubrication infrastructure. The lubrication mechanism is integrated into the crankcase, allowing it to share the engine's lubrication oil supply and drainage systems. This eliminates the need for separate lubrication components and simplifies the overall lubrication structure while ensuring adequate lubrication of the power transmission mechanism.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If the crankcase is designed as a single integrated structure, then the manufacturing is simplified, but the noise from cover vibrations cannot be minimized

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidnoise from cover vibrations
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The crankcase is segmented into multiple chambers: a main chamber for the engine components and a subsidiary chamber for the power transmission mechanism. The cover is correspondingly divided into a main cover and a chain case cover. This segmentation allows each cover portion to be independently designed and treated for vibration control, while still maintaining the integrated crankcase structure for manufacturing efficiency.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If the power transmission mechanism is disposed externally, then the lubrication access is improved, but the vehicle width is increased

Engineering Contradiction:
Improvelubrication accessVSAvoidvehicle width
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The lubrication access is merged with the engine's existing maintenance access points. Since the power transmission mechanism is integrated into the crankcase, the lubrication can be performed through the same access points used for engine maintenance. This eliminates the need for additional external access points, maintaining ease of lubrication while reducing vehicle width.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3760461B1Hybrid vehicle
Publication Date: 2023.08.23 KAWASAKI MOTORS LTD

AI summary

A hybrid vehicle (1) comprising: an engine (E) comprising a cylinder (Eb) and a crankshaft (Ea); a drive motor (M) comprising a motor housing (Ma) and a motor drive shaft (Mb) projecting laterally from the motor housing (Ma); a transmission (12) comprising an input shaft (12a), an output shaft (12b), and a gear train (12c), the transmission (12) being configured to change the speed of rotation produced by rotational power transmitted from the engine (E) and the drive motor (M) to the input shaft (12a) and output the resulting rotation to a drive wheel (3); a main clutch (13) connected to one end of the input shaft (12a) of the transmission (12) and disposed in a power transmission route between the crankshaft (Ea) of the engine (E) and the input shaft (12a) of the transmission (12); a crankcase (14) accommodating the crankshaft (Ea), the input shaft (12a), the output shaft (12b), the gear train (12c), and the main clutch (13); and a power transmission mechanism that transmits power from the motor drive shaft (Mb) to the input shaft (12a), wherein the crankcase (14) comprises: a main body portion (31) aligned with the drive motor (M) in a direction perpendicular to the motor drive shaft (Mb); and an extended portion (32) continuous with the main body portion (31) and located lateral to the motor housing (Ma), the extended portion (32) receiving insertion of one end of the motor drive shaft (Mb), and the power transmission mechanism is located partly in a first region defined by the main body portion (31) and partly in a second region defined by the extended portion (32) and communicating with the first region.