Hydraulic Travel Speed Switching to Reduce Shift Shock
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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 due to the lack of effective control over prime mover and traveling motor speeds.
Innovation Solution
A hydraulic system with a prime mover, traveling pumps, traveling motors, and a controller that adjusts the swash plate angle and motor speeds by using a traveling switching valve to switch between low and high speeds, reducing prime mover speed based on the machine's traveling condition to minimize shift shocks.
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 the sudden surge that causes shift shock during speed transition.
Solution Approach 2:
The controller anticipates the harmful effect of shift shock and applies counter-action by decreasing the swash plate angle before the switching occurs. This preliminary anti-action offsets the potential shock by pre-adjusting the hydraulic flow conditions.
2Use of energy by moving object
If the swash plate angle is maintained at a high angle for efficient power transmission, then energy efficiency is improved, but shift shock occurs during speed transitions
Solution Approach 1:
The controller temporarily decreases the swash plate angle before switching speeds to prevent shift shock, then restores it after switching. This preliminary action maintains energy efficiency during steady operation while preventing shock during transitions.
Solution Approach 2:
The swash plate angle is dynamically adjusted based on the switching state of the traveling switching valve. The angle decreases before switching and increases after switching, allowing the system to adapt to transition conditions while maintaining efficient operation during steady states.
3Productivity
If the traveling motor speed is increased from the first speed to the second speed, then productivity is improved, but the shift shock causes discomfort and potential damage
Solution Approach 1:
The controller decreases the swash plate angle before switching the traveling switching valve to enable high-speed operation. This preliminary action ensures smooth acceleration to the second speed without shift shock, improving productivity while maintaining comfort.
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 shift shocks and improves energy efficiency by synchronizing speed transitions, ensuring smooth acceleration and deceleration of working machines.
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 and to change a motor speed between a first speed and a second speed higher than the first speed
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.