Hydraulic Travel Speed Shift Control for Shock Mitigation
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Solution Overview
Problem
Existing working machines face challenges in mitigating speed-shift shock effectively, especially during deceleration, due to sudden changes in hydraulic fluid delivery and speed, which can lead to discomfort and reduced responsiveness.
Innovation Solution
The implementation of a controller that adjusts the control signal for the actuation valve in a specific pattern, with different reduction and increase rates, to manage the speed-shift of the traveling motor between first and second speeds, ensuring smoother transitions and reduced shock, while considering the traveling load and hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bleed fluid passage is disposed in a pressure-receiving portion of the hydraulic change-over valve to mitigate speed-shift shock, then the speed-shift shock is mitigated, but the number of parts increases
Solution Approach 1:
The patent extracts the shock mitigation function from a separate bleed fluid passage and integrates it into the actuation valve by providing a shock mitigation port that communicates with the actuator chamber. This allows the shock mitigation function to be achieved without adding separate parts, resolving the contradiction between shock mitigation and device complexity
Solution Approach 2:
The patent merges the shock mitigation function with the actuation valve by integrating the shock mitigation port into the valve structure. The shock mitigation port is formed as part of the valve body, combining multiple functions (flow control and shock mitigation) into a single component, thereby reducing the total number of parts while maintaining shock mitigation capability
2Object-affected harmful factors
If pressure characteristics in the shifting of the hydraulic change-over valve are changed to mitigate speed-shift shock, then the speed-shift shock is mitigated, but the responsiveness in deceleration is reduced
Solution Approach 1:
The patent implements dynamic control of the actuation valve opening degree based on real-time operating conditions. The controller adjusts the valve opening degree according to traveling speed, load, and other parameters, allowing the system to optimize between shock mitigation and responsiveness dynamically rather than using fixed pressure characteristics
Solution Approach 2:
The patent changes the control parameters (opening degree, duration) of the actuation valve based on operating conditions such as traveling speed and load. By dynamically adjusting these parameters, the system can mitigate shock when needed while maintaining responsiveness when required, resolving the contradiction between shock mitigation and deceleration responsiveness
3Object-affected harmful factors
If the control signal value is reduced to a mitigation value to mitigate speed-shift shock, then the shock is reduced, but the transitioning time increases
Solution Approach 1:
The patent uses periodic or staged adjustment of the control signal rather than a single large reduction. The controller adjusts the actuation valve opening degree in stages or periodically based on feedback, allowing shock mitigation to occur over an optimized time profile that balances shock reduction with transition speed
Solution Approach 2:
The patent implements feedback control where the controller monitors operating conditions and adjusts the control signal to the actuation valve accordingly. This closed-loop control allows the system to mitigate shock effectively while minimizing transition time by making real-time adjustments based on actual system state rather than predetermined fixed reductions
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 approach effectively mitigates speed-shift shock during deceleration, ensuring responsiveness and comfort by optimizing the control signal adjustments based on load and pressure conditions, thereby enhancing the operational performance of the working machine.
Implementation Method 1
a traveling pump including a swashplate and configured to deliver hydraulic fluid and change a flow rate of the hydraulic fluid delivered therefrom in correspondence to an angle of the swashplate
Implementation Method 2
an actuation valve provided upstream or downstream of the operation valve and fluidly connected to the operation valve
Data Source
AI summary
A working machine includes a prime mover, a traveling pump configured to deliver hydraulic fluid at a flow rate corresponding to an angle of the swashplate, a traveling motor configured to be rotated by the hydraulic fluid delivered from the traveling pump so as to have a rotation speed shiftable between a first speed and a second speed higher than the first speed, a traveling change-over valve shiftable between a first state to set the rotation speed of the traveling motor to the first speed and a second state to set the rotation speed of the traveling motor to the second speed, an operation device, an operation valve configured to change the angle of the swashplate of the traveling pump according to operation of the operation device, an actuation valve provided upstream or downstream of the operation valve and fluidly connected to the operation valve, and a controller configured or programmed to output a control signal to control the actuation valve in such a way that, when the traveling change-over valve is shifted from the second state to the first state, a value of the control signal is reduced from a set value to a mitigation value less than the set value and then restores to the set value. The controller is configured or programmed to reduce the value of the control signal from the set value to the mitigation value for a mitigation period in such a way that a first reduction rate that is a rate of reducing the value of the control signal for a first part of the mitigation period between a start point thereof and an intermediate point thereof larger than a second reduction rate that is a rate of reducing the value of the control signal for a second part of the mitigation period between the intermediate point thereof and an end point thereof.