Hydraulic Spool Valve Backlash Elimination via Pressure Plate
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Solution Overview
Problem
Hydraulic spool valves in duplex systems face synchronization issues due to manufacturing tolerances and wear, leading to backlash and potentially damaging 'force fight' between systems, which requires extremely tight manufacturing tolerances and is costly and time-consuming.
Innovation Solution
A hydraulic spool valve design incorporating a pressure plate and fluid path that utilizes hydraulic pressure to maintain contact between the drive lever and the actuator slot, eliminating backlash and allowing for cost-effective manufacturing without the need for tight tolerances, and self-compensating for wear over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extremely tight manufacturing tolerances are used to eliminate backlash, then synchronization precision is improved, but manufacturing cost and time increase
Solution Approach 1:
A pressure plate is introduced as an intermediary component between the drive lever and spool. This pressure plate is pushed by hydraulic pressure to maintain continuous contact and eliminate backlash, allowing the actuator slot to be manufactured with relaxed tolerances while still achieving precise spool synchronization.
Solution Approach 2:
Hydraulic pressure is utilized to push the pressure plate against the drive lever, maintaining continuous contact and eliminating backlash. This hydraulic mechanism allows for precise synchronization without requiring extremely tight manufacturing tolerances, thereby reducing manufacturing cost and time.
2Manufacturing precision
If tight manufacturing tolerances are applied to the actuator slot, then synchronization is improved, but wear compensation capability deteriorates
Solution Approach 1:
The pressure plate is designed to move dynamically in response to hydraulic pressure and wear. As the drive lever or slot wears over time, the pressure plate automatically adjusts its position to maintain continuous contact, providing ongoing backlash compensation without requiring tight tolerances or frequent adjustments.
Solution Approach 2:
The pressure plate automatically compensates for wear between the drive lever and actuator slot through its hydraulic actuation mechanism. As wear occurs, the pressure plate maintains contact by responding to pressure changes, providing self-compensating backlash elimination without external intervention or tight manufacturing tolerances.
3Reliability
If backlash is eliminated through tight tolerances, then force fight prevention is improved, but manufacturing complexity increases
Solution Approach 1:
The pressure plate serves as a mediator that ensures continuous contact between the drive lever and spool without requiring tight tolerances on the actuator slot. This intermediary component prevents backlash and force fight while allowing for simpler, less complex manufacturing processes.
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 ensures perfect synchronization of spool movement, eliminating force fights and reducing manufacturing costs and time, while maintaining system performance and preventing damage from backlash.
Implementation Method 1
a pressure plate and fluid path that utilizes hydraulic pressure to maintain contact between the drive lever and the actuator slot
Data Source
Figure 1
Figure 2a~2e
Figure 3
AI summary
A spool (20) for a hydraulic spool valve, comprising: a pressure chamber (23) for connecting a pressure line to a hydraulic cylinder; at least one return chamber (24, 25) for connecting the hydraulic cylinder to a reservoir; and an actuator slot (22) for receiving a drive lever (10); wherein the spool further comprises a fluid path (27) connecting said pressure chamber to said actuator slot and a pressure plate (26) movably mounted in the slot such that in use it is disposed between the fluid path and the drive lever. The pressure plate and pressurized fluid path of this spool essentially provide a preload device which utilizes the hydraulic pressure within the valve to reduce the effect of backlash. As the pressure pushes the plate against the drive lever, the drive lever is held firmly in place within the slot as it is pressed against the opposite wall of the slot. With this arrangement, there is no requirement for extremely tight tolerances in the manufacture of the actuator slot, thus reducing the manufacturing time and cost. For example, this arrangement allows the use of cost effective manufacturing methods. Also, backlash that would normally have developed over time due to wear does not result in backlash with this arrangement as the pressure plate will still ensure that contact is maintained between the drive lever, the pressure plate and the opposite wall of the slot. In other words, this arrangement is essentially self-compensating for wear.