Retarding System Controller for Work Machine Transmission
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Solution Overview
Problem
Existing retarding systems for large and heavy work machines, such as off-highway trucks, often result in inefficient operation due to automatic downshifting during engine braking, which can lead to operator adjustments and production losses when downshifting is undesirable.
Innovation Solution
A retarding system with a controller that determines the deceleration rate of a work machine and compares it to a threshold, preventing transmission downshifting if the manually operated braking mechanism is inactive, ensuring that downshifting only occurs when the operator has initiated braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automatic transmission downshifting is implemented during engine braking, then speed control is improved, but operator efficiency and production are reduced due to undesired downshifting
Solution Approach 1:
The controller monitors the operational state of the manually operated braking mechanism and uses this feedback to determine whether to permit automatic downshifting. When the braking mechanism is active, the controller allows downshifting to assist speed control; when inactive, the controller prevents downshifting to avoid interfering with operator intent, thereby resolving the contradiction between speed control and operator efficiency
2Reliability
If transmission downshifting is automatically controlled based on deceleration rate, then braking performance is improved, but system complexity increases
Solution Approach 1:
The controller pre-establishes a threshold deceleration rate and compares the actual deceleration rate against this threshold to determine whether automatic downshifting should be permitted. This preliminary comparison action simplifies the control logic by using a clear decision criterion rather than complex multi-parameter analysis, thereby improving braking performance while limiting system complexity
Data Source
AI summary
A retarding system for a work machine having a power source, a transmission, and a manually operated braking mechanism is disclosed. The retarding system has an engine retarder associated with the power source and a controller in communication with the transmission, the manually operated braking mechanism, and the engine retarder. The controller is configured to determine a deceleration rate of the work machine and compare the deceleration rate of the work machine to a predetermined threshold rate. The controller is also configured to determined if the manually operated braking mechanism is active and to cause the transmission to downshift if the deceleration rate is less than the predetermined threshold rate and the manually operated braking mechanism is determined to be active. The controller is further configured to prevent the transmission from downshifting if the deceleration rate is less than the predetermined threshold rate and the manually operated braking mechanism is determined to be inactive.