Mechanical Linkage Engine Braking with Lash Adjustment
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Solution Overview
Problem
Existing engine braking systems are limited by high complexity, cost, and incompatibility with smaller engines, requiring redesign of engine components, and are not easily retrofittable to existing engines, with hydraulic systems experiencing compliance issues and noise problems.
Innovation Solution
A mechanical linkage-based engine braking apparatus that modifies the existing valve lift to create a bleeder type engine brake, using rotatable, slidable, and ball-locking devices to transmit braking force without high compliance, allowing for installation on all engine types and retrofitting to existing engines, with a braking valve lash adjusting mechanism to reduce manufacturing tolerance requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic circuits are used to transmit mechanical input to exhaust valves for engine braking, then engine braking function is achieved, but system complexity and compliance issues increase
Solution Approach 1:
The patent replaces hydraulic circuits with a direct mechanical linkage system. A pushrod mechanically connects the fuel injector rocker arm to the exhaust valve, eliminating hydraulic fluid transmission. This mechanical substitution resolves compliance issues inherent in hydraulic systems while reducing overall system complexity by removing hydraulic components such as master pistons, slave pistons, and fluid circuits.
Solution Approach 2:
The patent extracts and removes the hydraulic circuit components from the engine braking system. By eliminating the master piston, slave piston, and hydraulic fluid transmission path, the design achieves engine braking through direct mechanical action alone, thereby reducing system complexity and eliminating compliance-related reliability issues.
2Reliability
If dedicated cam or valve train modifications are made for engine braking, then engine braking performance is improved, but manufacturing cost and incompatibility with existing engines increase
Solution Approach 1:
The patent makes the engine braking system universal by utilizing existing engine components for multiple functions. The fuel injector rocker arm serves both its normal function and as the actuator for engine braking. The exhaust valve serves both normal exhaust function and as the braking valve. This multi-functionality allows the system to be retrofitted to existing engines without dedicated cam modifications or specialized valve trains, thereby reducing manufacturing cost and improving compatibility.
Solution Approach 2:
The patent enables the existing engine components to serve themselves for engine braking. The fuel injector rocker arm's existing motion during normal operation is harnessed to actuate the exhaust valve for braking without requiring separate actuation mechanisms. This self-service approach eliminates the need for dedicated braking components, reducing manufacturing complexity and cost.
3Reliability
If mechanical linkage with ball-locking devices is used to transmit braking force, then compliance issues are eliminated, but device complexity increases
Solution Approach 1:
The patent applies ball-locking devices selectively at critical points in the mechanical linkage where force transmission reliability is most needed, rather than throughout the entire system. The balls lock the pushrod to the rocker arm at the point of maximum force transmission, providing reliability only where necessary. This partial application eliminates compliance issues at critical interfaces while minimizing overall device complexity.
4Manufacturing precision
If braking valve lash adjustment mechanism is added, then manufacturing tolerance requirements are reduced, but device complexity increases
Solution Approach 1:
The patent incorporates a pre-adjusted mechanical linkage system where the pushrod length and ball-locking position are predetermined during manufacturing to provide the correct valve lash. This preliminary action of setting the geometry during production eliminates the need for complex field-adjustable mechanisms, thereby reducing manufacturing tolerance requirements while minimizing added complexity.
Data Source
AI summary
Apparatus for modifying engine valve lift to produce an engine valve event in an internal combustion engine, the engine including at least one exhaust valve and an exhaust valve lifter for cyclically opening and closing the at least one exhaust valve, includes (a) an actuator for operating the at least one exhaust valve to produce said modified engine valve lift, said actuator having an inoperative position and an operative position; in said inoperative position said actuator being disengaged from the operation of the at least one exhaust valve, and in said operative position said actuator opening the at least one exhaust valve for said engine valve event; and (b) a controller for moving said actuator between said inoperative position and said operative position.