Compression Release Valvetrain for Engine Cranking Torque Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current engine cranking systems require high-cost, large motor generators or retain low-speed starters due to the high torque needed to turn engines at low speeds, necessitating improvements in engine cranking efficiency.
Innovation Solution
Implementing a valvetrain design with a compression brake valve profile that selectively opens exhaust valves during the upstroke of pistons, combined with a motor generator, to reduce engine torque requirements during cranking, allowing for compression release and potential removal of low-speed starters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a motor generator is added to replace the alternator for regenerative braking and torque application, then the low-speed starter can be removed, but a very large motor generator is required which increases cost and reduces payback period
Solution Approach 1:
The valve train performs preliminary action by opening exhaust valves during the compression stroke before the power stroke, releasing compressed gas to the exhaust manifold. This preliminary compression release reduces the work required during subsequent cranking operations, enabling a smaller motor generator to suffice.
Solution Approach 2:
The invention converts the harmful effect of compression resistance during cranking into a beneficial process. By deliberately opening exhaust valves during compression, the system transforms the resistance that hinders cranking into a mechanism that releases compression pressure, thereby reducing the torque burden on the motor generator.
2Use of energy by moving object
If a very large motor generator is used for effective brake regeneration at low engine speed, then regenerative braking is achieved, but cost increases and payback period lengthens
Solution Approach 1:
The valve train performs preliminary action by opening exhaust valves during the compression stroke before the power stroke, releasing compressed gas to the exhaust manifold. This preliminary compression release reduces the work required during subsequent cranking operations, enabling a smaller motor generator to suffice.
Solution Approach 2:
The invention changes the operational parameters of the valve train by activating exhaust valves during the compression stroke rather than following the conventional valve timing. This parameter change allows compression release that reduces cranking torque requirements, enabling cost-effective regenerative braking implementation.
3Weight of moving object
If a smaller motor generator is used, then cost is reduced, but a low-speed starter must be retained for starting which increases device complexity
Solution Approach 1:
The valve train performs preliminary action by opening exhaust valves during the compression stroke before the power stroke, releasing compressed gas to the exhaust manifold. This preliminary compression release reduces the work required during subsequent cranking operations, enabling a smaller motor generator to suffice.
Solution Approach 2:
The motor generator is designed to perform multiple functions: it serves as both the regenerative braking device and the engine starter. The compression release valvetrain enables the motor generator to effectively crank the engine at reduced speeds, allowing it to fulfill both roles without requiring a separate low-speed starter.
4Force
If compression release valvetrain is implemented, then cranking torque is reduced, but valve actuation mechanism complexity increases
Solution Approach 1:
The valve actuation mechanism is segmented into distinct functional components: camshafts for normal valve operation, a compression release camshaft for compression stroke valve opening, and a switching mechanism. This segmentation allows each component to perform its specific function efficiently, managing the overall complexity through modular design.
Solution Approach 2:
The valve actuation mechanism employs dynamic switching between different camshaft profiles based on engine operating conditions. During cranking, the compression release camshaft is engaged to open exhaust valves; during normal operation, the standard camshafts control valve timing. This dynamic adaptability reduces cranking torque while maintaining normal performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the torque needed to turn the engine during cranking, enabling efficient engine cranking with a smaller motor generator and eliminating the need for a low-speed starter, thereby improving engine efficiency and reducing costs.
Implementation Method 1
a lifting mechanism having a compression brake valve profile configured to selectively lift the exhaust valves on a downstroke of the cylinders in response to a cranking condition of the internal combustion engine, wherein the compression braking valve profile is phased to the upstroke of the pistons
Data Source
AI summary
Systems, apparatuses and methods are disclosed that include an internal combustion engine including a plurality of cylinders operable by a valve actuation mechanism including a lifting mechanism having a compression brake valve profile configured to selectively lift the exhaust valves on a downstroke of the cylinders in response to a cranking condition of the internal combustion engine, wherein the compression braking valve profile is phased to the upstroke of the pistons.