Vehicle Control Device Slope Parking Torque Reduction
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Solution Overview
Problem
In vehicles equipped with shift-by-wire and brake-by-wire systems, the inability to reduce the required torque of the shift actuator for parking lock when the BBW automatic operation function is disabled, especially when stopped on a slope, hinders efficient parking lock performance.
Innovation Solution
The vehicle control device includes a disabling determination part, a vehicle stop determination part, and a slope determination part, which, in conjunction with the BBW automatic operation part, automatically operates the brake device when the vehicle is stopped on a slope, regardless of the disabling request, thereby suppressing vehicle movement due to gravity and allowing for a longer operation time of the shift range switching mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the BBW automatic operation function is disabled, then the driver has full control over brake operation, but the shift actuator cannot reduce its required torque for parking lock when stopped on a slope
Solution Approach 1:
The brake device is activated in advance before the parking lock operation is completed. When the vehicle is stopped on a slope and the shift range is in travel ranges, the brake control device automatically activates the brake device to hold the vehicle, preventing it from rolling during the parking lock process. This preliminary braking action allows the shift actuator to operate without needing to overcome gravitational force, enabling torque reduction even when BBW automatic operation is disabled.
2Reliability
If the shift range switching mechanism operates for a long time to achieve parking lock, then the parking lock can be securely engaged, but the shift actuator requires higher torque especially on slopes
Solution Approach 1:
The brake device serves as an intermediary between the vehicle's gravitational force and the shift actuator. By activating the brake device during the parking lock process on slopes, it mediates the gravitational force that would otherwise require the shift actuator to overcome. This allows the shift range switching mechanism to operate for the necessary duration to achieve secure parking lock engagement without requiring excessive torque from the shift actuator.
3Productivity
If the brake device is not activated during parking lock on slope, then the system operates normally, but the vehicle may move due to gravity during the switching process
Solution Approach 1:
The brake device is activated in advance to counteract the harmful effect of gravitational force before the vehicle can move during the parking lock process. When the vehicle is stopped on a slope and the shift range is in travel ranges, the brake control device automatically activates the brake device to prevent vehicle movement. This preliminary anti-action against gravity ensures the vehicle remains stationary throughout the parking lock operation, eliminating the harmful effect of potential vehicle movement.
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
This solution enables the parking lock to be performed even with a relatively long operation time of the shift range switching mechanism, reducing the required torque of the shift actuator and potentially downsizing the shift actuator, while ensuring the brake device operates effectively to prevent vehicle movement on slopes.
Implementation Method 1
automatically operates the brake device... suppressing vehicle movement due to gravity
Data Source
AI summary
A brake control device is a control device for a vehicle used in a vehicle on which the shift-by-wire system and the brake-by-wire system are mounted. A function of automatically operating the brake device without an operation of the driver of the vehicle is referred to as a BBW automatic operation function, and a request by the driver for disabling the BBW automatic operation function is referred to as a disabling request. A brake control device includes a disabling determination part configured to determine a presence or absence of the disabling request, the vehicle stop determination part configured to determine whether the vehicle is stopped, a slope determination part configured to determine whether the vehicle is located on a slope, and a BBW automatic operation part. The BBW automatic operation part operates the brake device when the vehicle is stopped on the slope even if the disabling request is made.