Hydraulic VCT End Plate Seal for Air Ingress Prevention
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Solution Overview
Problem
Hydraulically-actuated variable camshaft timing assemblies in internal combustion engines face issues with fluid leaks and air introduction due to insufficient oil pressure, leading to suboptimal phasing and efficiency losses.
Innovation Solution
Incorporating an end plate seal with an angled planar surface and a fluid groove that communicates engine oil between chambers, preventing air introduction by ensuring fluid continuity even at low oil pressure levels, and using materials like glass-filled nylon or Teflon for the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic pressure is used to actuate the VCT assembly, then camshaft timing control is achieved, but fluid leaks and air introduction occur due to insufficient sealing
Solution Approach 1:
The patent employs a flexible end plate seal made of elastomeric material that conforms to the mating surfaces between the end plate and rotor. This flexible film structure creates an effective barrier against fluid leakage and air introduction, resolving the sealing performance issue while maintaining the hydraulic actuation function.
Solution Approach 2:
The end plate seal is constructed from composite materials including elastomeric base material reinforced with glass-filled nylon or Teflon. This composite structure provides both the flexibility needed for sealing and the structural integrity to withstand hydraulic pressures, preventing both fluid leaks and air introduction.
2Loss of energy
If oil pressure is reduced to improve engine efficiency, then parasitic losses decrease, but fluid continuity is compromised and air may enter the system
Solution Approach 1:
The flexible end plate seal maintains its sealing effectiveness across a wide range of oil pressures. Even when oil pressure is reduced to improve engine efficiency, the elastomeric seal continues to prevent air introduction and maintain fluid continuity, allowing the system to operate reliably at lower pressures.
Solution Approach 2:
The seal material properties are selected to maintain sealing effectiveness across varying pressure conditions. The elastomeric material with specific durometer and reinforcement provides consistent sealing performance whether oil pressure is high or reduced, enabling energy-efficient operation without compromising fluid continuity.
3Reliability
If precise dimensions are specified for end plates to control fluid flow, then manufacturing complexity increases, but sealing effectiveness is maintained
Solution Approach 1:
The flexible end plate seal compensates for dimensional variations and manufacturing tolerances in the end plate and rotor mating surfaces. The elastomeric material deforms to conform to slight irregularities, maintaining effective sealing without requiring extremely precise dimensional control, thus reducing manufacturing complexity while preserving fluid flow control.
Solution Approach 2:
The sealing function is localized to the end plate seal component rather than requiring the entire end plate structure to achieve precise dimensions. The seal material provides the necessary sealing quality at the critical interface, allowing other portions of the end plate to be manufactured with standard tolerances, reducing overall device complexity.
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 effectively prevents air from entering the fluid chambers, maintaining optimal engine performance by ensuring continuous fluid flow and pressure transmission, thereby enhancing the efficiency and reliability of the camshaft phaser under varying oil pressure conditions.
Implementation Method 1
an end plate seal abutting the end plate(s) and the radial surface of the rotor
Implementation Method 2
Hydraulically-actuated variable camshaft timing assemblies in internal combustion engines face issues with fluid leaks and air introduction due to insufficient oil pressure
Data Source
AI summary
A hydraulically-actuated variable camshaft timing (VCT) assembly, including a stator having one or more fluid chambers; a rotor received by the stator, and configured to be angularly displaced relative to the stator, having one or more radially extending vanes positioned within the fluid chambers; one or more end plates coupled with the stator and at least partially defining the fluid chambers; and an end plate seal abutting the end plate(s) and the radial surface of the rotor.