Construction Machine Exhaust Brake Control for Engine Speed
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Solution Overview
Problem
Construction machines face frequent switching of the exhaust brake, which reduces the durability of engine parts, as they rely on exhaust brake to prevent high engine revolution speeds during downhill traveling.
Innovation Solution
A construction machine equipped with an exhaust adjustment mechanism and a control device that automatically executes the exhaust brake during downhill traveling, based on specific conditions, to maintain engine speed without frequent on-off switching, and includes additional mechanisms like fan motor speed control and lock-up devices to manage engine load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If exhaust brake is used to prevent high engine revolution speed during downhill traveling, then engine speed control is improved, but frequent on-off switching reduces durability of engine parts
Solution Approach 1:
The control device determines whether a downhill traveling condition is satisfied in advance and activates the exhaust brake before the engine revolution speed becomes excessively high. This preliminary action prevents the need for frequent on-off switching by maintaining continuous brake application during downhill conditions, thereby protecting engine parts while controlling speed
Solution Approach 2:
The control device continuously monitors engine revolution speed and load factor, using this feedback to determine when to activate or deactivate the exhaust brake. This closed-loop control ensures the brake is applied only when needed (during downhill traveling with high speed and low load), preventing frequent switching while maintaining engine speed within safe limits
2Speed
If exhaust brake is frequently switched on and off to control engine speed, then engine speed control is achieved, but durability of engine parts such as turbocharger deteriorates
Solution Approach 1:
The system determines downhill traveling conditions in advance and activates the exhaust brake proactively, preventing excessive engine speed before it occurs. This eliminates the need for reactive on-off switching that would harm the turbocharger, while maintaining appropriate engine speed throughout the downhill descent
Solution Approach 2:
The exhaust brake is maintained in a continuous active state during downhill traveling conditions rather than being switched on and off. This continuous application provides steady engine speed control while minimizing mechanical stress and heat cycles on the turbocharger, extending its service life
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
Prevents engine revolution speeds from becoming too high during downhill travel using exhaust brake without frequent switching, reducing the need for foot brake usage and ensuring engine speed control through various load management strategies.
Implementation Method 1
to prevent the engine revolution speed from becoming too high, there is a method of, when the engine revolution speed becomes a threshold or more, reducing a flow rate of exhaust from the engine to increase a load of the engine (i.e., so-called exhaust brake)
Data Source
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AI summary
A construction machine includes: an engine driving at least one hydraulic pump configured to supply operating oil to a hydraulic actuator; an exhaust adjustment mechanism adjusting a flow rate of exhaust from the engine; and a control device controlling the exhaust adjustment mechanism. The control device determines whether or not a first downhill traveling condition and/or a second downhill traveling condition are/is satisfied. When at least one of the first downhill traveling condition and the second downhill traveling condition is satisfied, the control device controls the exhaust adjustment mechanism such that the exhaust adjustment mechanism executes exhaust brake.