Hydraulic Flow Restriction for Valve Deactivation Air Removal
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Solution Overview
Problem
Existing valve deactivation systems in engines face challenges with air entrainment in hydraulic circuits, leading to prolonged mode transition times and reliability issues due to particulate matter accumulation, which affects the pressure differential and maintenance costs.
Innovation Solution
A hydraulic circuit with a poppet valve deactivation control valve, featuring oil galleries and a hydraulic flow restriction machined into the camshaft carrier, includes interchangeable oil filters to reduce air and particulate matter, ensuring reliable operation and minimizing leakage and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If air is present within the latch pin hydraulic circuit, then the mode transition time increases due to air compressibility, but the system structure remains simple
Solution Approach 1:
The patent extracts air from the hydraulic circuit by providing a dedicated air vent passage that allows air to escape from the latch pin hydraulic circuit to the atmosphere or oil reservoir, preventing air compressibility from delaying mode transitions
Solution Approach 2:
The patent introduces an intermediary air vent passage that mediates between the hydraulic circuit and the external environment, allowing controlled air removal without compromising the sealed hydraulic system
2Reliability
If flow constriction regions are used to create pressure differential for air expansion, then air expansion is controlled, but particulate matter accumulates at the constriction regions
Solution Approach 1:
The patent removes the flow constriction regions from the hydraulic circuit design, eliminating the locations where particulate matter would accumulate and degrade the constricting function
Solution Approach 2:
The patent converts the harmful effect of air expansion into a beneficial controlled process by allowing air to vent naturally through the air vent passage without using constriction regions that would trap particulates
3Object-generated harmful factors
If a combined restrictor/filter is used to filter oil, then particulate matter is reduced, but leakage occurs at the dam interface and filter degradation requires complete unit replacement
Solution Approach 1:
The patent removes the combined restrictor/filter assembly from the hydraulic circuit, eliminating the leakage interface between the dam and restrictor/filter and the need for costly complete unit replacements
Solution Approach 2:
The patent allows the hydraulic system to self-regulate oil flow without requiring a separate filter component, using the natural viscosity and flow characteristics of the oil to prevent particulate accumulation
4Reliability
If mode transitions occur only when the cam is on the base circle portion, then mode change occurs without load, but the transition window is limited by cam rotational speed
Solution Approach 1:
The patent prepares the hydraulic system for mode transition in advance by maintaining ready-to-switch hydraulic connections and ensuring the latch pin mechanism is pre-positioned, allowing rapid transition when the base circle window is available
Solution Approach 2:
The patent uses hydraulic pressure control to enable rapid mode transitions, using oil pressure to quickly actuate the latch pin and switch between activated and deactivated modes within the limited base circle window
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
The solution enhances transition times between activated and deactivated states, reduces maintenance costs, and maintains consistent pressures within the hydraulic circuit, improving the reliability and efficiency of valve deactivation mechanisms.
Implementation Method 1
During activated cylinder conditions, pressure in the first oil gallery may be greater than in the second oil gallery, and oil may flow from the first gallery to the second gallery via the restricted flow
Implementation Method 2
One method for activating and deactivating the rocking arm includes an oil-pressure actuated latch pin within the inner arm of the rolling finger follower
Data Source
AI summary
Methods and systems are provided for deactivating a valve actuation mechanism. In one example, a system may include a hydraulic gallery that may deliver a restricted flow of hydraulic fluid from a hydraulic flow restrictor to a pressure relief valve within a valve deactivation oil control valve, and during a second condition may deliver an unrestricted flow of hydraulic fluid from the valve deactivation oil control valve to the hydraulic flow restrictor. The hydraulic flow restrictor may comprise two vertical bores within the camshaft carrier that are fluidically coupled via a restrictive groove on the bottom surface of the camshaft carrier.