Vehicle Braking Force Controller Engine Braking Adaptation
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Solution Overview
Problem
Conventional vehicle braking force control devices experience difficulties in performing braking as intended by the driver when a large braking force from engine braking is acting, leading to slow or difficult braking due to unnecessary antilock brake control intervention.
Innovation Solution
A vehicle braking force control device that adjusts the slip ratio threshold for antilock brake control based on accelerator position, clutch connection, and power transmission signals, temporarily changing the threshold to prevent unnecessary intervention during engine braking, allowing the brake device to function as envisioned by the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antilock brake control is performed based on a fixed slip ratio threshold, then wheel slip can be prevented under normal braking conditions, but unnecessary intervention occurs during engine braking causing delayed or difficult brake device response
Solution Approach 1:
The patent applies dynamics by making the slip ratio threshold variable rather than fixed. The control device dynamically adjusts the threshold based on detected engine braking states, switching between a first threshold (for normal braking) and a second threshold (for engine braking). This allows the system to adapt to different operating conditions, preventing unnecessary antilock brake intervention during engine braking while maintaining effective control during normal braking operations.
Solution Approach 2:
The patent implements parameter changes by modifying the slip ratio threshold parameter according to the operating state. When engine braking is detected through analysis of accelerator position, clutch connection, and power transmission signals, the system changes the threshold from the first value to the second value. This parameter adjustment prevents false detection of wheel slip during engine braking, thereby avoiding unnecessary antilock brake control activation and ensuring timely brake device response.
2Reliability
If the slip ratio threshold is lowered to prevent wheel slip during engine braking, then wheel slip can be controlled, but the brake device becomes slower to respond when the driver intends to brake
Solution Approach 1:
The patent applies preliminary action by detecting engine braking states in advance through monitoring accelerator position, clutch connection, and power transmission signals. Before wheel slip actually occurs during engine braking, the system has already switched to the appropriate threshold, preventing false antilock brake activation. This preliminary detection and response mechanism ensures that when the driver applies the brakes, the brake device responds immediately without unnecessary delays from false slip detection.
3Device complexity
If a fixed threshold value is used for antilock brake control, then the control logic is simple, but the system cannot distinguish between normal braking and engine braking conditions
Solution Approach 1:
The patent introduces an intermediary detection mechanism that monitors accelerator position, clutch connection state, and power transmission state. These intermediary signals serve as indicators to distinguish between normal braking and engine braking conditions. Based on the combination of these intermediary signals, the system determines the current operating state and selects the appropriate slip ratio threshold, enabling the system to adapt to different braking conditions without requiring complex control logic.
Data Source
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AI summary
It is an object of the present invention to provide a vehicle braking force control device that can cause a brake device to perform braking as envisioned by a driver even in a situation where a large braking force resulting from engine braking is acting. A vehicle braking force control device that is installed in a vehicle and which, at a normal time, performs antilock brake control at a time when the slip ratio of a wheel has become equal to or greater than a predetermined threshold acquires from the engine control unit an accelerator pedal position signal corresponding to an accelerator pedal position, a clutch connection signal corresponding to a state of connection of a clutch, and a power transmission signal corresponding to a state of power transmission of a transmission, and at a time when the vehicle braking force control device has determined that the action of engine braking is large on the basis of the accelerator pedal position signal, the clutch connection signal, and the power transmission signal, the vehicle braking force control device changes the predetermined threshold value to an offset threshold value that makes it harder to perform the antilock brake control than at the normal time.