Off-Road Powertrain Layout for Low-Center-of-Gravity 4WD
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Solution Overview
Problem
Off-road vehicles face challenges in maintaining a low center of gravity due to constraints on the placement of heavier components like the engine, which limits stability in rough conditions, especially in four-wheel or all-wheel drive vehicles where the drivetrain must pass under the engine.
Innovation Solution
A powertrain arrangement with a rear drive unit that includes an engine positioned mostly to one lateral side of the vehicle's center, allowing for a compact configuration with the transmission and rear drive, and a forward drive assembly extending past the engine, enabling the engine to be placed at a relatively low position while accommodating air and exhaust flow systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the drivetrain extends under the engine to reach both front and rear wheels, then four-wheel or all-wheel drive capability is achieved, but the engine placement is limited and the center of gravity cannot be lowered
Solution Approach 1:
The drivetrain is segmented into separate front and rear drive assemblies. The rear drive assembly includes the engine, transmission, and rear final drive connected in sequence. The front drive assembly is connected to the transmission and extends forward, allowing independent routing of drive components without requiring the drivetrain to pass under the engine.
Solution Approach 2:
The engine is positioned laterally to one side of the vehicle center rather than centrally, and the drivetrain components are arranged in a longitudinal sequence (engine-rear transmission-rear final drive) rather than vertically stacked under the engine. This dimensional reconfiguration allows the engine to be placed at a lower position while maintaining four-wheel drive capability.
2Stability of the object's composition
If the engine is placed at a lower position to lower the center of gravity, then vehicle stability is improved, but the drivetrain cannot extend under the engine to reach both wheels
Solution Approach 1:
The drivetrain is divided into separate front and rear drive assemblies that can be independently configured. This segmentation allows the rear drive unit to be positioned low in the vehicle for stability while the front drive assembly extends forward from the transmission without requiring the drivetrain to pass under the engine.
Solution Approach 2:
The drivetrain components are arranged in a longitudinal dimension (engine-rear transmission-rear final drive connected in sequence) rather than being constrained to a vertical arrangement under the engine. This allows the engine to be positioned at a lower vertical position while maintaining proper drivetrain connectivity to both front and rear wheels.
3Volume of moving object
If the engine is positioned laterally to one side for compact arrangement, then space efficiency is improved, but air flow and exhaust flow systems require alternative positioning
Solution Approach 1:
The engine is positioned asymmetrically to one lateral side of the vehicle center, creating an asymmetric layout for the rear drive unit. The air flow and exhaust flow systems are then configured to accommodate this asymmetric positioning, with components such as the turbocharger and exhaust manifold arranged to the side of the engine rather than following conventional symmetric layouts.
Solution Approach 2:
The air flow and exhaust flow systems are locally adapted to the engine's lateral position. The turbocharger and exhaust components are positioned in the lateral space adjacent to the engine rather than requiring central or under-engine placement, allowing the compact lateral arrangement to be maintained while providing proper airflow and exhaust pathways.
Data Source
AI summary
A vehicle including a frame; an engine connected to the frame, the engine comprising a crankshaft extending longitudinally, the crankshaft rotating about a crankshaft axis extending longitudinally; a transmission disposed rearward of the engine, the transmission being operatively connected to the crankshaft, the crankshaft being received at least in part in the transmission, the transmission including a plurality of axles and gears for altering a gear ratio of the vehicle, at least one of the plurality of axles rotating about an axis parallel to the crankshaft axis; a rear final drive disposed rearward of and being operatively connected to the transmission; a drive shaft assembly extending forward from the transmission; and a front final drive operatively connected to the at least one front ground engaging member, the front final drive being disposed forward of the engine, the front final drive being operatively connected to the drive shaft assembly.