Pilot-Actuated Hydraulic Cylinder Float Mode for Terrain Following
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Solution Overview
Problem
Existing electro-hydraulic actuators (EHAs) do not allow operation in modes other than extending, retracting, and holding, limiting their application in scenarios where minimal resistance and terrain-following are necessary, such as in snow plowing, grading, and agricultural tillage.
Innovation Solution
A pilot-actuated valve assembly that fluidly couples the chambers of a hydraulic cylinder actuator to a reservoir, enabling a float mode where the piston can move with minimal resistance, allowing an implement to follow a surface by generating a pilot fluid signal to control fluid flow between the chambers and the reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the EHA operates in traditional extending, retracting, or holding modes, then the piston can effectively lift and position the implement, but the implement cannot follow the terrain with minimal resistance
Solution Approach 1:
The valve assembly is designed to dynamically switch between different operational modes (extend, retract, hold, and float) based on pilot fluid pressure. The spool valve can be positioned in different locations to create different fluid pathways, enabling the system to adapt its behavior dynamically. This dynamic switching capability allows the implement to transition from controlled positioning to free-floating terrain-following mode.
Solution Approach 2:
A pilot fluid pressure source is introduced as an intermediary control mechanism to actuate the valve assembly. The pilot fluid pressure serves as a mediator between the control system and the main hydraulic circuit, enabling mode selection without directly controlling the main piston. This intermediary approach allows for sophisticated control logic while maintaining system simplicity.
2Adaptability or versatility
If the valve assembly is designed to enable float mode, then the implement can follow terrain with minimal resistance, but the device complexity increases due to additional pilot port and fluid signaling mechanism
Solution Approach 1:
The valve assembly is designed as a multi-functional component that can perform multiple operations (extend, retract, hold, and float modes) through a single integrated structure. The spool valve with its different positional states serves multiple purposes: controlling fluid flow direction for extension and retraction, maintaining position during holding mode, and enabling free flow to reservoir during float mode. This universal design avoids the need for separate valves for each function.
Solution Approach 2:
The patent utilizes hydraulic principles to control the valve actuation through pilot fluid pressure. The pilot port receives pressurized fluid that acts on the spool valve to shift it into the float position. This hydraulic control mechanism leverages the existing hydraulic infrastructure of the system, using fluid pressure as the control medium rather than requiring separate mechanical or electrical actuation systems.
3Adaptability or versatility
If the pilot fluid signal is used to actuate the valve assembly, then the float mode can be activated, but the loss of time occurs during mode transition due to fluid pressure buildup and valve response
Solution Approach 1:
The pilot fluid pressure source is pre-positioned and ready to deliver pressurized fluid to the pilot port. The valve assembly is designed with pre-established fluid pathways that can be quickly activated. The spool valve is positioned and spring-loaded to respond rapidly when pilot pressure is applied, minimizing the time required to transition between modes. The system is prepared in advance to enable quick mode switching when terrain-following is required.
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 the hydraulic cylinder actuator to operate in a float mode, allowing the implement to follow terrain with minimal resistance, enhancing the versatility of EHAs in various surface-engaging applications.
Implementation Method 1
the pilot fluid signal actuates the valve assembly to fluidly couple the first workport and the second workport to the reservoir port
Data Source
AI summary
An example hydraulic system has: a hydraulic cylinder actuator having a cylinder and a piston axially movable in the cylinder, wherein the piston has a piston head that divides an internal space of the cylinder into a first chamber and a second chamber; a fluid reservoir; a pilot pressure source that generates a pilot fluid signal; and a valve assembly controlling fluid flow to and from the hydraulic cylinder actuator, wherein the valve assembly has a first workport fluidly coupled to the first chamber, a second workport fluidly coupled to the second chamber, a reservoir port fluidly coupled to the fluid reservoir, and a pilot port fluidly coupled to the pilot pressure source to receive the pilot fluid signal, wherein the pilot fluid signal actuates the valve assembly to fluidly couple the first workport and the second workport to the reservoir port, thereby operating the piston in a float mode.