Bias Piston Rocker Arm Actuation for Engine Braking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine braking systems require hydraulic fluid passages within rocker arms, which are difficult to implement and add cost, necessitating a non-hydraulic or alternative hydraulic means to bias a rocker arm away from a dedicated cam lobe during non-engine braking modes.
Innovation Solution
A lost motion valve actuation system with a bias mechanism using a bias piston and spring, combined with hydraulic fluid supply passages and a solenoid valve, allows for non-hydraulic or hydraulic biasing of a rocker arm, enabling efficient engine braking without hydraulic fluid within the rocker arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic fluid passages are incorporated within the rocker arm to bias it during non-engine braking modes, then the engine braking functionality is maintained, but the device complexity and manufacturing cost increase
Solution Approach 1:
The biasing function is separated from the rocker arm by introducing a dedicated bias piston and bias spring assembly. This segmentation allows the rocker arm to focus on valve actuation while the separate bias mechanism provides the necessary positioning force during non-braking modes, reducing complexity within the rocker arm structure itself.
Solution Approach 2:
The hydraulic fluid passages and biasing mechanism are extracted from the rocker arm and relocated to a separate bias piston assembly. This extraction eliminates the need for complex internal passages within the rocker arm, simplifying its structure and reducing manufacturing difficulty while maintaining the essential biasing function.
2Force
If hydraulic fluid passages are incorporated within the rocker arm, then the biasing force can be applied, but the ease of manufacture decreases due to implementation difficulty
Solution Approach 1:
The biasing force generation is segmented into a separate bias piston and bias spring assembly, eliminating the need to machine complex hydraulic passages within the rocker arm. This segmentation allows each component to be manufactured independently using simpler processes, improving ease of manufacture while still delivering the required biasing force.
Solution Approach 2:
The hydraulic fluid pressure system is replaced with a mechanical bias spring system acting on the bias piston. This substitution eliminates the need for hydraulic passages within the rocker arm, replacing them with a simpler mechanical arrangement that is easier to manufacture and assemble.
3Power
If a dedicated cam lobe is used for engine braking, then the engine braking power is enhanced, but the device complexity increases due to additional cam and rocker arm requirements
Solution Approach 1:
The dedicated engine braking cam lobe is merged with the existing camshaft structure, and the bias piston assembly is integrated into the housing rather than being a separate component. This merging reduces the number of discrete parts and simplifies the overall system architecture while maintaining the enhanced engine braking power provided by the dedicated cam profile.
Solution Approach 2:
The bias piston assembly serves multiple functions: it provides biasing force during non-braking modes, controls the engagement of the dedicated cam lobe, and works in conjunction with the master and slave pistons. This multi-functionality reduces the need for separate components, thereby reducing device complexity while maintaining enhanced braking power.
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 effectively biases the rocker arm to prevent engine braking during non-braking modes, reducing complexity and cost while maintaining engine braking functionality, by using a bias piston and spring mechanism that overcomes the limitations of hydraulic fluid passages within rocker arms.
Implementation Method 1
the bias mechanism including a bias piston disposed within a bias piston bore extending through the housing and wherein the bias piston extends from the housing to contact the rocker arm
Implementation Method 2
a master piston slidably disposed in a master piston bore provided in the housing wherein the master piston bore communicates with at least one of the fluid supply passages
Implementation Method 3
a solenoid valve communicating with at least one of the fluid supply passages
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A lost motion valve actuation system includes an engine brake housing and one or more hydraulic fluid supply passages extending through the housing. Master and slave pistons are slidably disposed corresponding bores in the housing. The master and slave pistons are used to provide selective actuation to one or more engine valves. An engine brake rocker arm disposed adjacent to the housing includes a master piston contact surface and a bias mechanism contact surface. A bias mechanism is disposed in the housing and includes a bias piston which extends from the housing. The bias piston biases the rocker arm out of contact with an engine cam during select engine operation modes, such as during a positive power mode of operation. The bias piston may be mechanically or hydraulically repositioned to permit the rocker arm to contact the engine cam during a second mode of engine operation, such as an engine braking mode.