Hybrid Clamp Force Control for Fast, Synchronized Lift Truck Clamps
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Solution Overview
Problem
Existing hydraulic control systems for lift truck attachments face challenges in achieving high-speed closure of clamps without damaging the load, and they often require complex systems or flow dividers that limit efficiency and speed.
Innovation Solution
A hydraulic control circuit that alternately links and unlinks hydraulic actuators during different modes of operation, allowing high-speed movement without the need for flow dividers, by using a selector valve to coordinate the movement of hydraulic cylinders or motors based on pressure thresholds and mode changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high closing pressure is used to achieve high-speed closure of clamps, then closure speed is improved, but clamp force against the load becomes excessively high causing load damage
Solution Approach 1:
The closing operation is divided into two distinct phases: a first closing phase with high pressure for rapid approach, and a second closing phase with reduced pressure for gentle contact. This segmentation allows the system to achieve both high closure speed and low impact force by transitioning between pressure levels at the appropriate moment.
Solution Approach 2:
The system performs preliminary high-speed closure to bring the clamps close to the load, then transitions to a controlled low-pressure phase just before contact. This preliminary action allows the majority of the closing distance to be covered at high speed, with only a small final adjustment made at low pressure to prevent damage.
2Stability of the object's composition
If flow dividers are used to coordinate clamp movement, then synchronized movement is achieved, but system complexity and cost increase
Solution Approach 1:
The hydraulic system merges the control of multiple clamps into a single integrated circuit without flow dividers. By using a common hydraulic source and coordinated control valves, the system achieves synchronized movement through unified pressure control, eliminating the need for separate flow division mechanisms.
Solution Approach 2:
The hydraulic system uses the natural equalization of pressure throughout the fluid network to automatically synchronize clamp movement. The incompressible hydraulic fluid naturally distributes pressure evenly to all actuators, providing self-synchronization without requiring complex external coordination devices.
3Object-affected harmful factors
If low initial pressure is used to prevent load damage, then load protection is improved, but closure speed decreases
Solution Approach 1:
The system dynamically adjusts pressure levels during the closing operation, transitioning from high pressure to low pressure at the optimal moment. This dynamic pressure control allows the system to optimize both speed and protection by adapting the pressure profile to the real-time position and contact status of the clamps.
Solution Approach 2:
The closing operation uses periodic pressure modulation with distinct high-pressure and low-pressure phases. This periodic action pattern allows rapid closure during high-pressure phases while ensuring gentle contact during low-pressure phases, achieving both speed and protection goals through rhythmic pressure variation.
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
Enables high-speed, synchronized closure of clamps while minimizing load damage, improving efficiency and reducing the risk of clamp force imbalances.
Implementation Method 1
a first hydraulic actuator (20) selectively operable from a first configuration where the first hydraulic actuator is hydraulically linked to the second hydraulic actuator (22) to coordinate movement of the second hydraulic actuator (22) with movement of the first hydraulic actuator (20)
Data Source
AI summary
A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.