Engine Brake Piston Reset via Discharge Valve
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Solution Overview
Problem
Existing engine brake systems for automotive vehicles lack reliable mechanisms for resetting the activation piston to its initial position, leading to potential compromises in engine brake performance due to extended valve lift overlap.
Innovation Solution
A valve actuation mechanism featuring a stopper fixed to the engine housing that exerts a force to open a discharge valve, reducing fluid pressure and mechanically moving the activation piston back to its first position, ensuring reliable operation by incorporating a rod with a pushing zone and a spring-biased discharge valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is provided to prevent fluid flow out of the chamber, then the piston remains in the actuation position, but the piston cannot be reset to its initial position when engine brake is not needed
Solution Approach 1:
The invention extracts the reset function from the main control valve by introducing a separate discharge valve that can independently release control fluid from the chamber. This allows the piston to be reset without interfering with the main control valve's function of directing pressurized fluid to maintain piston position during engine brake operation.
Solution Approach 2:
The discharge valve acts as an intermediary mechanism between the chamber and the external environment, providing a controlled path for fluid escape. This intermediary component enables the piston reset function while maintaining the integrity of the main control system.
2Device complexity
If the control valve is the only component controlling fluid flow, then the system is simpler, but the piston cannot be reset quickly enough if retraction is needed for a period inferior to one revolution of the camshaft
Solution Approach 1:
The control system is segmented into two independent valves: the control valve for directing pressurized fluid to the chamber, and the discharge valve for rapidly emptying the chamber. This segmentation allows each valve to be optimized for its specific function, with the discharge valve capable of rapid fluid release for quick piston reset.
Solution Approach 2:
The discharge valve is preliminarily positioned and configured to enable rapid fluid discharge when activated. This preliminary preparation allows the system to achieve fast piston reset when needed, without requiring complex active control mechanisms during the reset operation.
3Ease of operation
If the check valve is forced open to allow control fluid to escape, then the piston can be reset, but the mechanism is unreliable and the discharge valve may not open consistently
Solution Approach 1:
The discharge valve is designed as a self-actuating component that opens automatically when reset conditions are met, without requiring external forcing mechanisms. The valve uses the system's own control fluid pressure to actuate its opening, ensuring reliable and consistent operation.
Solution Approach 2:
The invention replaces the unreliable mechanical forcing of the check valve open with a controlled fluid pressure system. The discharge valve uses fluid pressure differential to reliably open and close, substituting unpredictable mechanical forcing with controllable hydraulic actuation.
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 enhances the reliability of the valve actuation mechanism by allowing independent mechanical resetting of the activation piston for each rocker, improving the efficiency and effectiveness of the engine brake function.
Implementation Method 1
a stopper fast with the housing and adapted to exert, on a portion of the piston, a force for opening the discharge valve
Implementation Method 2
a discharge valve movable in translation with respect to the rocker and adapted to reduce fluid pressure in the chamber
Implementation Method 3
spring-biased discharge valve
Implementation Method 4
movable with respect to the rocker under action of a fluid pressure raise in a chamber fluidly linked to the bore
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
This valve actuation mechanism (S) for an internal combustion engine (E) on an automotive vehicle comprising rockers (9) moved by a camshaft (2), each rocker (9) being adapted to exert a valve opening force (F9) on at least a portion of a valve actuation mechanism of each cylinder belonging to a housing (E1) of the engine (E), via an engine brake activation piston (95), housed in a bore (94) of the rocker (9), and movable with respect to the rocker (9) under action of a fluid pressure raise in a chamber (101) fluidly linked to the bore (96), from a first position, in which an engine brake function is deactivated, to a second position, in which a roller (93) of the rocker (9) reads at least one engine brake bump of a cam (22) of the camshaft (2) so as to perform the engine brake function, each rocker (9) comprising a discharge valve (99) movable in translation with respect to the rocker (9), adapted to reduce fluid pressure in the chamber (101), wherein the engine brake system (S) comprises, for each rocker (9), a stopper (13) fast with the housing (E1) and adapted to exert, on a portion (961) of the piston (95), a force (F13) for opening the discharge valve (99) when the activation piston (95) has to be moved from its second position to its first position.