Throttle Control System for Work Machine Operator Safety
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Solution Overview
Problem
Existing work machines lack an effective system to safely limit engine throttle and ground speed when the operator is not present on the platform, potentially leading to unsafe operation or equipment damage.
Innovation Solution
A control system that utilizes a platform switch to detect operator presence, sending signals to a controller to limit the engine throttle and hydraulic flow, thereby restricting the ground drive speed without reducing engine RPM, using a proportional pressure reducing valve to divert excess hydraulic flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the operator platform is left unmonitored, then the machine can operate at full throttle and speed, but safety risks increase and equipment damage may occur
Solution Approach 1:
The system continuously monitors operator presence on the platform through a platform switch and provides feedback to the controller. When the operator is absent, the controller automatically limits the throttle signal to a predetermined maximum level, preventing unsafe high-speed operation. This closed-loop feedback mechanism ensures safety without requiring constant operator intervention.
Solution Approach 2:
The controller acts as an intermediary between the operator's throttle input and the ground drive system. It receives the throttle signal from the operator and, based on platform occupancy status, modulates the signal before transmitting it to the ground drive motor controller, thereby enforcing speed limits when needed.
2Reliability
If the throttle is limited when operator is absent, then safety is improved, but machine productivity decreases
Solution Approach 1:
The system dynamically adjusts the throttle limitation based on real-time platform occupancy conditions. When the operator is present on the platform, full throttle authority is restored, allowing the machine to operate at maximum productivity. When absent, the system automatically applies speed limits. This dynamic adaptation eliminates the need for permanent productivity reduction while maintaining safety.
3Reliability
If a platform switch is installed to detect operator presence, then safety control is enabled, but device complexity increases
Solution Approach 1:
The platform switch serves multiple functions: it detects operator presence for safety control, and can potentially serve other machine functions. The controller integrates this sensor input into the existing throttle control system, leveraging existing processing capabilities rather than adding dedicated separate systems, thereby minimizing overall complexity increase.
4Speed
If the controller limits hydraulic flow to the ground drive motor, then ground speed is restricted, but engine power for attachments is maintained
Solution Approach 1:
The hydraulic system is segmented into separate controllable circuits: one serving the ground drive motor and another serving hydraulic attachments. The controller can independently limit hydraulic flow to the ground drive motor while maintaining full hydraulic power availability for attachments. This segmentation allows selective speed restriction without compromising attachment performance.
Data Source
AI summary
A hydraulic control system for use with a work machine. The work machine has a platform which supports an operator. When the operator is not on the platform, the platform moves into a first position, causing a signal generator to send a signal to a controller. The controller is configured to limit the hydraulic flow to the ground drive motor when the platform is in the first position. The controller may directly reduce operation of the engine, or may adjust a valve which diverts a portion of hydraulic flow. The limitation may be overridden when desired by the operator.