Hydraulic Clutch Pressure Sequencing for Two-Gear Transmissions
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Solution Overview
Problem
In hydraulic control systems for two-gear transmissions, especially in construction machines, the inconsistent engagement of clutches can lead to damage due to simultaneous power transmission, stress on components, and uncomfortable knockback, primarily because contemporary systems rely on orifices and accumulators whose performance varies with temperature and wear, causing inconsistent transmission characteristics.
Innovation Solution
The hydraulic control system incorporates a first and second pressure chamber with movable members, a hydraulic command circuit, a switchable valve, and check and restricting orifices to coordinate the engagement and disengagement of clutches, ensuring that the first clutch disengages before the second engages, and adjusting the hydraulic pressure to prevent simultaneous engagement and reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If orifices and accumulators are used to control clutch engagement, then the system structure is simple, but the transmission characteristics become inconsistent due to temperature and wear effects
Solution Approach 1:
The patent replaces the traditional mechanical orifice and accumulator system with a servo-controlled valve system. The servo valve uses electronic sensors and actuators to precisely control hydraulic fluid flow to the clutch, replacing passive mechanical flow restriction with active electronic control. This substitution eliminates the temperature and wear sensitivity of mechanical orifices while maintaining system simplicity through integrated control electronics.
Solution Approach 2:
The patent implements a feedback control system where sensors monitor clutch position, hydraulic pressure, and transmission state, and this information is fed back to the control unit. The control unit adjusts the servo valve in real-time to maintain consistent clutch engagement characteristics regardless of temperature changes or component wear, ensuring reliable and repeatable transmission performance.
2Productivity
If clutches are engaged simultaneously during gear change, then the gear change speed is fast, but damage occurs due to simultaneous power transmission and stress on components
Solution Approach 1:
The patent uses the servo-controlled system to prepare for gear changes in advance. Before a gear change is initiated, the control system pre-positions the clutches and adjusts hydraulic pressure to optimal levels. During the transition, the servo valve precisely sequences clutch disengagement and engagement, ensuring the outgoing clutch is fully disengaged before the incoming clutch engages, preventing simultaneous power transmission and component stress while maintaining fast gear change speed.
Solution Approach 2:
The patent implements dynamic control of clutch engagement through the servo valve system that continuously adjusts hydraulic fluid flow based on real-time transmission state. Unlike fixed mechanical timing, the servo system can dynamically adapt clutch engagement sequences to load conditions, speed transitions, and temperature, optimizing the gear change process to prevent component damage while maintaining high productivity.
3Reliability
If hydraulic pressure is increased to improve clutch engagement force, then clutch engagement becomes more reliable, but wear on clutch components increases
Solution Approach 1:
The patent uses the servo-controlled valve to dynamically adjust hydraulic pressure parameters during clutch engagement. Instead of using consistently high pressure, the system applies precisely controlled pressure profiles that provide sufficient engagement force only when needed, then reduces pressure during normal operation. This parameter optimization maintains reliable clutch engagement while minimizing cumulative stress and wear on clutch components, extending their service life.
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 ensures safe and consistent clutch engagement, reducing the risk of damage and stress on components by coordinating clutch operations, maintaining consistent transmission characteristics over time, and minimizing the impact of temperature and wear on system performance.
Implementation Method 1
a pressure in the fluid, for example a hydraulic pressure, propagates from the first member to the second member being in fluid communication and reverse
Implementation Method 2
The switchable valve (53) may be in a second state where the passage of the hydraulic fluid through the switchable valve is restricted along a restricted passage way (56) which may be an embodiment of a restricting orifice
Data Source
AI summary
The present disclosure describes a hydraulic control system comprising a first pressure chamber and a second pressure chamber, each pressure chamber configured to receive a hydraulic fluid, a first movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the first pressure chamber and a second movable member configured to assume a position depending on a hydraulic pressure of the hydraulic fluid in the second pressure chamber, a hydraulic command circuit configured to provide the hydraulic fluid and to control the hydraulic pressure of the hydraulic fluid in the first pressure chamber and/or the second pressure chamber, having a switchable valve in fluid communication with the first pressure chamber, wherein the switchable valve is configured to be pilotable depending on the hydraulic pressure of the hydraulic fluid in the second pressure chamber.