Hydraulic Valve Lash Compensator for Engine Braking
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Solution Overview
Problem
Existing engine braking systems in internal combustion engines require complex and costly hydraulic valve clearance compensation mechanisms, which can lead to structural weaknesses and additional component requirements, and face challenges in maintaining efficient braking performance and valve closure after engine braking.
Innovation Solution
A mechanical transmission device with a hydraulic valve clearance compensation element that uses a piston, check valve, and spring to actuate the exhaust valve, where the hydraulic valve clearance compensation element takes on a dual function of maintaining a maintenance-free valve train and enhancing engine braking by keeping the exhaust valve open during braking, and a control device delays fuel injection to ensure complete valve closure after braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hydraulic valve clearance compensation mechanism with additional hydraulic control units is used for engine braking, then engine braking performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the engine braking function with the existing hydraulic valve clearance compensation mechanism. The hydraulic valve clearance compensation element is integrated into the valve bridge and serves dual purposes: maintaining valve clearance and enabling engine braking through its pressure chamber and check valve, eliminating the need for separate hydraulic control units
Solution Approach 2:
The hydraulic valve clearance compensation element is designed to perform multiple functions: it compensates for valve clearance variations and simultaneously acts as an engine brake by keeping the exhaust valve open during compression stroke, utilizing the existing oil pressure system for both purposes
2Power
If numerous hydraulic pistons and pressure lines are arranged in the valve bridge for engine braking, then engine braking capability is enhanced, but structural strength decreases and component size increases
Solution Approach 1:
The patent merges the engine braking function into the existing hydraulic valve clearance compensation structure. The same piston, pressure chamber, and check valve used for valve clearance compensation are utilized for engine braking, eliminating the need for additional hydraulic components that would weaken the valve bridge
Solution Approach 2:
The hydraulic valve clearance compensation element serves dual functions: maintaining valve clearance and providing engine braking. This multi-functionality eliminates the need for separate engine braking components, preserving the structural integrity and compactness of the valve bridge
3Reliability
If a relief valve and hold-down device are added to prevent uncontrolled valve lash adjuster pumping during engine braking, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The check valve in the hydraulic valve clearance compensation element automatically prevents uncontrolled pumping of the valve lash adjuster during engine braking by allowing oil to flow in one direction only. This self-regulating mechanism eliminates the need for additional relief valves and hold-down devices, maintaining reliability while simplifying the structure
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 simplifies and cost-saves the engine braking system by eliminating the need for additional components, ensuring reliable valve closure and maintaining braking performance without the need for relief lines or hold-down devices, while allowing for precise control of engine braking power.
Implementation Method 1
an oil pressure line opening into the pressure chamber via a check valve
Implementation Method 2
a spring
Data Source
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AI summary
The invention relates to an internal combustion engine with at least one exhaust valve per cylinder actuated via a camshaft and a transmission device, wherein a hydraulic valve lash compensating element is arranged in the transmission device between the camshaft and the exhaust valve, and with an engine braking device comprising an engine exhaust brake for building up exhaust back pressure and a decompression brake with which at least one exhaust valve can be kept open at least during an engine braking phase, wherein the decompression brake is formed by the hydraulic valve lash compensating element.The internal combustion engine further comprises a control device for controlling the fuel injection, which is designed to restart fuel injection after the end of an engine braking operation only after a predetermined delay time has elapsed, the predetermined delay time being set to be greater than the closing time of the exhaust valve after the end of the engine braking operation.