Hydraulic Clutch Control for Coordinated Two-Gear Shifting
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Solution Overview
Problem
In hydraulic control systems for two-gear transmissions, particularly in construction machines, the inconsistent engagement of clutches during gear changes can lead to potential damage due to simultaneous engagement of both gears while transmitting power, caused by temperature-dependent orifice effects and clutch wear, resulting in unpredictable transmission performance and operator discomfort.
Innovation Solution
The hydraulic control system incorporates a first and second pressure chamber with movable members connected to clutches, a switchable valve, and hydraulic networks with check and restricting orifices to coordinate clutch engagement and disengagement, ensuring the second clutch is disengaged before the first clutch engages, using a control unit to manage hydraulic pressure and prevent simultaneous engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If temperature-dependent orifice effects are used for clutch control, then the hydraulic control system can be simpler, but the transmission performance becomes inconsistent and unpredictable
Solution Approach 1:
The patent replaces temperature-dependent hydraulic orifices with a mechanically controlled valve system operated by a pushrod actuator. This mechanical substitution eliminates the thermal sensitivity of hydraulic orifices while maintaining simple device architecture through direct mechanical linkage between the actuator and clutch engagement mechanism.
Solution Approach 2:
The patent changes the control parameter from hydraulic pressure (temperature-dependent) to mechanical displacement (temperature-independent). The pushrod actuator provides direct mechanical displacement control that is not affected by temperature variations, ensuring consistent clutch engagement timing and transmission performance across different operating conditions.
2Speed
If clutch engagement timing is not coordinated, then the gear change process can be faster, but simultaneous engagement of both gears causes transmission damage
Solution Approach 1:
The patent implements preliminary disengagement of the outgoing clutch before engagement of the incoming clutch through a coordinated valve control sequence. The control valve first directs hydraulic pressure to disengage the outgoing clutch, then after a controlled time delay, engages the incoming clutch. This preliminary action sequence prevents simultaneous engagement and eliminates transmission damage while maintaining efficient gear change speed.
Solution Approach 2:
The patent employs feedback through hydraulic pressure sensors and control valves that monitor the engagement state of each clutch. The control system receives feedback on clutch position and adjusts the engagement timing accordingly, ensuring that the outgoing clutch is fully disengaged before the incoming clutch engages, thus preventing transmission damage while optimizing gear change speed.
3Productivity
If clutch engagement is rapid, then productivity is improved, but operator discomfort increases due to knockback
Solution Approach 1:
The patent implements periodic, staged clutch engagement through a multi-phase valve control sequence. Instead of a single rapid engagement, the system uses a series of controlled pressure applications: first disengaging the outgoing clutch, then partially engaging the incoming clutch, and finally completing the engagement. This periodic action sequence maintains high gear change efficiency while reducing sudden torque transfers that cause operator knockback and discomfort.
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 coordinated clutch engagement, reducing wear and temperature dependency, maintaining consistent transmission performance and preventing damage by ensuring the second clutch is disengaged before the first clutch engages, thus enhancing operational safety and reducing operator discomfort.
Implementation Method 1
uses a hydraulic fluid, like mineral oil, under a hydraulic pressure to control further devices
Implementation Method 2
a switchable valve (53) which is configured to be in a first state allowing a free passage of the hydraulic fluid through the switchable valve (53) to and/or from the first pressure chamber (10) and a second state restricting the passage of the hydraulic fluid through the switchable valve (53) to and/or from the first pressure chamber (10)
Implementation Method 3
hydraulic networks (40, 50) with check and restricting orifices
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.