Hydraulic Travel Speed Switching With Swash Plate Shock Control
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Solution Overview
Problem
Existing hydraulic systems for working machines face challenges in efficiently managing speed transitions between low and high speeds, leading to shift shocks and inefficient energy use, particularly due to the lack of effective control over the prime mover's revolving speed and swash plate angle of the traveling pumps.
Innovation Solution
The system incorporates a prime mover, traveling pumps with swash plates, traveling motors, a traveling switching valve, and a controller that adjusts the swash plate angle and prime mover speed to smoothly transition between low and high speeds by reducing the prime mover's revolving speed and swash plate angle, utilizing a controller device to manage these changes based on the working machine's condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the traveling switching valve is switched from the first state to the second state to increase motor speed, then the traveling motor rotates at the second speed (higher speed), but shift shock occurs during the speed transition
Solution Approach 1:
The controller decreases the swash plate angle before switching the traveling switching valve from the first state to the second state. This preliminary action reduces the flow rate of operation fluid in advance, preventing sudden hydraulic pressure changes and shift shock during the speed transition. The swash plate angle is restored to the original angle after the switching is complete.
2Productivity
If the swash plate angle is maintained at a high angle during speed switching, then the flow rate of operation fluid is high for quick acceleration, but energy is wasted during the transition period
Solution Approach 1:
The controller decreases the swash plate angle before the switching valve changes state, preparing the hydraulic system for the upcoming speed transition. This preliminary reduction in flow rate prevents energy waste by avoiding unnecessary high-flow operation during the transition period, while still enabling quick acceleration when needed.
Solution Approach 2:
The controller monitors the state of the traveling switching valve and the operating conditions of the working machine, dynamically adjusting the swash plate angle based on feedback signals. This feedback mechanism ensures optimal energy efficiency by maintaining appropriate flow rates only when necessary for performance.
3Object-affected harmful factors
If the swash plate angle is decreased before switching the traveling switching valve, then shift shock is reduced during speed transition, but the flow rate of operation fluid decreases temporarily
Solution Approach 1:
The swash plate angle is decreased temporarily before the switching valve changes state, and then restored to the original angle after switching. This temporary reduction in flow rate is acceptable because it occurs only during the brief transition period and enables smoother speed changes without permanent performance loss.
Solution Approach 2:
By decreasing the swash plate angle before switching, the system cushions the upcoming speed transition by reducing hydraulic pressure buildup. This beforehand cushioning prevents shift shock while the flow rate is temporarily reduced, and the system returns to full performance after the transition completes.
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 solution reduces shift shocks and improves energy efficiency by synchronizing speed transitions, ensuring smoother operation and reduced wear on machine components.
Implementation Method 1
a traveling pump having a swash plate to change a flow rate of outputting of operation fluid in accordance with an angle of the swash plate
Implementation Method 2
a traveling motor to be rotated by the operation fluid outputted by the traveling pump
Data Source
AI summary
A working machine includes a prime mover, a traveling pump to be driven by the prime mover to output operation fluid, a traveling motor to be driven by the operation fluid outputted from the traveling pump and to change a motor speed between a first speed and a second speed higher than the first speed, a machine body on which the prime mover, the traveling pump, and the traveling motor are arranged, a traveling switching valve to be switched between a first state allowing the traveling motor to rotate at the first speed and a second state allowing the traveling motor to rotate at the second speed, and a controller to reduce a revolving speed of the prime mover based on a traveling condition of the machine body in switching the traveling switching valve between an accelerating state to switch the traveling switching valve from the first state to the second state and a decelerating state to switch the traveling switching valve from the second state to the first state.