Engine RPM Suppression Mode Cancellation for Working Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine-driven working machines face safety concerns during engine startup due to the centrifugal clutch engaging prematurely, causing unintended operation of the working unit. Additionally, the RPM suppression mode, intended to prevent this, can be overly restrictive, delaying the cancellation of the mode and hindering the worker's ability to start work promptly.
Innovation Solution
The working machine incorporates an optimized RPM suppression mode cancellation system. This system uses a combination of engine operational state parameters and environmental conditions to set flexible cancellation conditions, ensuring worker safety during startup while allowing for prompt operation once conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the throttle valve is set half open for cold start, then the engine can be started reliably with increased air-fuel mixture, but the engine RPM exceeds the clutch-in RPM causing the centrifugal clutch to become engaged and the operating unit to act abruptly
Solution Approach 1:
The brake system is activated before engine startup to create a counteracting force that prevents the operating unit from moving when the centrifugal clutch engages. This preliminary protective action counteracts the harmful effect of abrupt operating unit activation during cold start operations.
Solution Approach 2:
The brake system acts as an intermediary mechanism between the engine startup process and the operating unit. By applying braking force to the drive wheel, it mediates the power transmission path, allowing the centrifugal clutch to engage without causing the operating unit to move unexpectedly.
2Object-affected harmful factors
If the RPM suppression mode is maintained with strict cancellation conditions, then worker safety is ensured by preventing engine RPM from exceeding clutch-in RPM, but the engine does not respond to throttle lever operation and work cannot be started promptly
Solution Approach 1:
The RPM suppression mode cancellation conditions are made dynamic rather than static. The control device monitors multiple parameters including throttle valve opening degree, engine RPM, and operating unit state, and cancels the suppression mode when any one of several possible conditions is met. This dynamic approach allows the system to transition from safety mode to operational mode more quickly while maintaining safety guarantees.
Solution Approach 2:
The system changes multiple parameters simultaneously to determine mode cancellation: throttle valve opening degree, engine RPM values, time duration, and operating unit state. By monitoring changes in these parameters and using logical combinations (OR conditions), the system can exit suppression mode under various scenarios, improving responsiveness while maintaining safety.
3Ease of operation
If the throttle valve is operated to fully open for work startup, then the engine should respond immediately, but the engine RPM is inhibited from rising under RPM suppression mode control
Solution Approach 1:
The control device continuously monitors the throttle valve opening degree and uses this feedback to determine when to cancel the RPM suppression mode. When the throttle valve is detected to be fully opened, this feedback signal triggers the cancellation of suppression mode, allowing the engine RPM to respond immediately to the throttle input without artificial limitation.
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 optimized cancellation conditions for the RPM suppression mode allow for safer and more efficient engine startup, ensuring the worker's safety while enabling prompt initiation of work tasks. By dynamically adjusting the cancellation conditions based on various parameters, the system balances safety and operational efficiency.
Implementation Method 1
a centrifugal clutch disposed between the internal-combustion engine and the operating unit. The centrifugal clutch becomes engaged when the internal-combustion engine RPM is higher than a predetermined clutch-in RPM
Implementation Method 2
The working machine includes a brake system so that the operating unit can be braked by the brake system
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
To satisfy both a request for ensuring worker's safety at the engine start and a worker's request for promptly starting a work, on the premise of a working machine including an engine RPM suppression mode. A working machine (1) has a centrifugal clutch (6). The engine RPM suppression mode is executed at the start of an internal combustion engine (2). With the RPM suppression mode, the RPM of the internal combustion engine (2) is controlled not to exceed a clutch-in RPM. The working machine (1) has a mode cancelling means (S5) canceling the engine RPM suppression mode when a predetermined mode cancelation condition for cancelling the engine RPM suppression mode is satisfied, and a cancellation condition changing means (S2) changing the mode cancelation condition depending on a change in an engine operational state and/or an environment.