Engine Braking Valve Actuation via Segmented Hydraulic Units
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Solution Overview
Problem
Existing engine braking systems require active control and are prone to reliability issues due to varying tolerances and tightness, leading to unnecessary energy expenditure and increased wear, with defects in piston-cylinder units affecting overall system functionality.
Innovation Solution
The first and second piston-cylinder units are arranged on separate elements within the connecting mechanism, allowing for a delay in their response behavior, minimizing undesired influences and enabling passive control without electronic or hydraulic control lines, with independent oil supply to each unit to ensure functionality even if one is defective.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If active control with oil pressure is used to open the outlet valve for engine braking, then the braking effect is achieved, but the system reliability decreases due to varying tolerances and tightness affecting pressure build-up
Solution Approach 1:
The system is segmented into two independent piston-cylinder units: the first piston-cylinder unit for engine braking control and the second piston-cylinder unit for valve clearance compensation. Each unit has its own oil supply path, eliminating the series connection problem where one defect would affect the other. This segmentation isolates reliability issues to individual units while maintaining overall system functionality.
Solution Approach 2:
The system transitions from active hydraulic control to passive operation by utilizing the engine's own motion and existing oil pressure fluctuations to control the exhaust valve opening. The cam mechanism and natural oil pressure variations during engine operation automatically actuate the first piston-cylinder unit without requiring external control lines or active intervention, thereby improving reliability.
2Device complexity
If the oil duct runs through multiple elements in series connection, then the system is compact, but a defect in one piston-cylinder unit affects the functionality of the other unit
Solution Approach 1:
The oil supply system is segmented into separate supply paths for the first piston-cylinder unit and the second piston-cylinder unit. Both units draw oil from a common oil source (the oil supply in the rocker arm bearing area), but each has an independent oil duct connection. This ensures that a defect or blockage in one oil duct does not affect the oil supply to the other unit, maintaining functional independence and overall system reliability.
3Stability of the object's composition
If the system runs through both cams during non-braking condition, then the camshaft rotation is maintained, but unnecessary energy is expended and wear increases
Solution Approach 1:
The compression release cam function is extracted and made optional rather than mandatory. During non-braking conditions, the system can operate with only the main exhaust cam, removing the unnecessary action of the compression release cam. The compression release cam is only activated when engine braking is required, eliminating wasted energy and reduced wear during normal operation while maintaining camshaft rotation continuity through the main cam.
4Device complexity
If the first and second piston-cylinder units are arranged on the same element, then the structure is simplified, but the response behavior of the units interferes with each other
Solution Approach 1:
The first piston-cylinder unit and the second piston-cylinder unit are segregated onto different structural elements: the first unit is integrated into the intermediate element (valve bridge), while the second unit is integrated into the rocker arm. This spatial segmentation prevents interference between the units' response behaviors while maintaining a relatively simple overall structure. The independent mounting locations allow each unit to respond to its specific control signals without being influenced by the other unit's operations.
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 design reduces wear, minimizes frictional resistance, and achieves a more reliable engine braking system with reduced energy consumption and increased durability by decoupling the oil channels and using mass inertia to delay the movement of the rocker arm, thus preventing undesirable movements and accelerations.
Implementation Method 1
a first piston-cylinder unit for the temporary intermediate opening of an exhaust valve
Implementation Method 2
a second piston-cylinder unit for counteracting valve lash
Implementation Method 3
using mass inertia to delay the movement of the rocker arm, thus preventing undesirable movements and accelerations
Data Source
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AI summary
Internal combustion engine with at least one combustion chamber from which exhaust gas can be discharged by means of at least one exhaust valve, comprising an engine braking device with a hydraulic valve control unit integrated into a connecting mechanism linking the exhaust valve to a camshaft and holding the exhaust valve in an intermediately open position when the engine braking device is actuated, and a hydraulic valve lash compensation mechanism for the exhaust valve, wherein the connecting mechanism comprises at least one rocker arm and an intermediate element arranged between the rocker arm and the exhaust valve, and the hydraulic valve control unit of the engine braking device comprises a first piston-cylinder unit for temporarily opening an exhaust valve, and the hydraulic valve lash compensation mechanism comprises a second piston-cylinder unit for counteracting valve lash.wherein the first piston-cylinder unit is arranged in or on the intermediate element and the second piston-cylinder unit is arranged in or on the rocker arm.