Hydraulic VCT Phasing With Temperature-Dependent Fluid Switching

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Solution Overview

Problem

Existing hydraulic VCT phasers face limitations in phasing speed due to fluid flow restrictions, particularly at lower temperatures, leading to unwanted rotor oscillations and inefficient angular displacement of the camshaft relative to the crankshaft.

Innovation Solution

A hydraulic VCT assembly with a contorted fluid path and hydraulic switch assembly that regulates fluid flow between advancing and retarding chambers based on temperature, using logic valves to control fluid flow rates, ensuring efficient phasing at lower temperatures and preventing oscillations at higher temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluid flow is restricted in hydraulic VCT phaser, then rotor oscillations are prevented at higher temperatures, but phasing speed decreases at lower temperatures

Engineering Contradiction:

Improverotor oscillation preventionVSAvoidphasing speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent implements a temperature-dependent fluid flow control system where the fluid path characteristics change dynamically with temperature. At lower temperatures, the fluid path allows higher flow rates for faster phasing, while at higher temperatures, the same path provides flow restriction to prevent rotor oscillations. This dynamic adaptation resolves the contradiction between speed and stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the fluid flow parameters (flow rate, pressure) based on temperature conditions. The contorted fluid path is designed with specific geometric characteristics that naturally provide different flow resistance at different temperatures, allowing the system to optimize phasing speed at low temperatures while preventing oscillations at high temperatures through parameter variation.

Inventive Principle:

Principle #35Parameter changes

2Speed

If fluid flow rate is increased for faster phasing, then camshaft angular displacement speed improves, but rotor oscillations occur at higher temperatures

Engineering Contradiction:

Improvecamshaft angular displacement speedVSAvoidrotor oscillation control

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The contorted fluid path acts as an intermediary element between the fluid source and the chambers. Its specific geometry creates a natural flow restriction that mediates between the need for high flow rates (for speed) and the need for flow control (to prevent oscillations). The fluid path's design allows it to automatically provide appropriate flow resistance based on operating conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If fluid path is simplified for easier manufacturing, then device complexity reduces, but fluid flow control precision at different temperatures deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidfluid flow control precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent employs a contorted (curved) fluid path instead of a straight path. This curvature is intentionally designed to provide the necessary flow control characteristics at different temperatures. The curved path creates increased flow resistance that can be tuned through geometric parameters, allowing precise control of fluid flow rates without requiring complex additional components.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

Enhances the speed and stability of camshaft phasing by optimizing fluid flow according to temperature changes, improving engine performance and reducing rotor oscillations.

Implementation Method 1

a hydraulic switch assembly positioned in the rotor to regulate a flow of fluid between an advancing chamber and a retarding chamber through the vane

Methodology Applied

Scientific EffectTemperature-based fluid flow regulation:

Implementation Method 2

a contorted fluid path, in fluid communication with the hydraulic switch assembly, sized and shaped so that fluid flow from a fluid source maintains a fluid valve in a position that permits fluid flow between the advancing chamber and the retarding chamber at or below a predetermined temperature

Methodology Applied

Scientific EffectFluid pressure positioning: Pressure Gradient

Data Source

PatentUS12392265B2Hydraulic variable camshaft timing with a temperature based hydraulic switch

Publication Date: 2025.08.19 BORGWARNER INC

AI summary

A hydraulic variable camshaft timing (VCT) assembly including a stator having at least one fluid chamber; and a rotor, received by and angularly displaceable relative to the stator, having at least one vane positioned within the fluid chamber extending radially outwardly from a hub, and a hydraulic switch assembly positioned in the rotor to regulate a flow of fluid between an advancing chamber and a retarding chamber through the vane.