Articulated Work Machine Steering Flow Control for End-Stop Impact
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Solution Overview
Problem
In work machines with direct steering systems, the high flow rate and large pressure make it difficult to mitigate impacts at the steering terminating edge without using a pilot method, and conventional rubber cushions are inadequate to absorb the energy.
Innovation Solution
A work machine with a variable capacity pump and controller that adjusts hydraulic fluid discharge based on frame angle detection to reduce the discharge flow rate, mitigating impacts by controlling the steering speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rubber cushion is disposed on the frames to mitigate impact, then the impact at steering terminating edge is reduced, but the large amount of energy cannot be absorbed and shock is generated
Solution Approach 1:
The patent applies dynamics by making the hydraulic pump's discharge flow rate variable rather than fixed. The pump's discharge flow rate is dynamically adjusted based on the steering angle detected by the frame angle detecting section. When the steering angle approaches the terminating edge, the discharge flow rate is reduced, which controls the steering speed and mitigates impact. This dynamic adjustment resolves the contradiction by adapting the energy absorption capability to the actual operating conditions.
Solution Approach 2:
The patent changes the parameter of discharge flow rate from constant to variable. By changing the discharge flow rate parameter of the hydraulic pump based on steering angle, the system can absorb large amounts of energy during normal operation while reducing energy discharge near the terminating edge to prevent excessive shock. This parameter change enables the system to resolve the contradiction between impact mitigation and energy absorption.
2Object-affected harmful factors
If a stop valve is installed in the pilot circuit to block hydraulic pressure, then impact is mitigated at maximum steering angle, but the system cannot be applied to direct steering systems with high flow rate and large pressure
Solution Approach 1:
The patent replaces the static stop valve approach with a dynamic control system. Instead of using a stop valve that blocks pressure at a fixed point, the system dynamically adjusts the hydraulic pump's discharge flow rate based on real-time steering angle detection. This dynamic approach makes the system adaptable to direct steering systems with high flow rates and large pressures, resolving the contradiction between impact mitigation and system versatility.
Solution Approach 2:
The patent introduces an intermediary control system consisting of the frame angle detecting section and the controller. This intermediary system mediates between the steering operation and the hydraulic pump, allowing the system to mitigate impact in direct steering systems without requiring a stop valve in the pilot circuit. The intermediary enables the system to adapt to different steering system types, resolving the contradiction.
3Object-affected harmful factors
If the discharge flow rate of the variable capacity pump is reduced based on frame angle detection, then impact at steering terminating edge is mitigated, but steering speed is controlled which may affect operation responsiveness
Solution Approach 1:
The patent applies periodic action by adjusting the discharge flow rate in different steering phases. During normal steering operation, the pump operates at full capacity for responsive steering. When the steering angle approaches the terminating edge (detected by the frame angle detecting section), the discharge flow rate is periodically reduced to mitigate impact. This periodic adjustment resolves the contradiction by providing fast steering response when needed while preventing impact at the boundaries.
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 system effectively reduces impacts at the steering terminating edge by adjusting hydraulic fluid flow, ensuring smoother operation and operator awareness of impending contact.
Implementation Method 1
The variable capacity pump discharges the hydraulic fluid to the valve. The controller reduces the discharge flow rate of the variable capacity pump on the basis of a detection value of the frame angle detecting section.
Implementation Method 2
The hydraulic cylinder drives the second frame with respect to the first frame.
Data Source
AI summary
A work machine, includes steering cylinders that drive a front frame with respect to a rear frame. A directional control valve changes a supply amount of hydraulic fluid to the steering cylinders. A steering wheel operates the directional control valve. A variable capacity pump discharges the hydraulic fluid to the directional control valve. Cylinder stroke sensors are provided for detecting the turning angle of the front frame with respect to the rear frame. A controller reduces the discharge flow rate of the variable capacity pump on the basis of the detection values of the cylinder stroke sensors.