Vehicle Braking Force Maintenance via Pawl Engagement Control
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Solution Overview
Problem
The existing electric braking devices for vehicles face issues with maintaining braking force due to semi-engagement of the pawl member with the ratchet gear, leading to a decrease in braking force applied to the wheels, as the detection of engagement state is inaccurate, causing the pawl member to incorrectly determine its position and fail to regulate the ratchet gear's rotation effectively.
Innovation Solution
A braking-force-maintaining device that includes a displacement member with teeth, a pawl member, and a control device, which performs specific lock processes to ensure the pawl member is either normally engaged or disengaged with the displacement member, using position detection and torque control to prevent semi-engagement and maintain the braking force by adjusting the displacement member's position and torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pawl member is pressed against the ratchet gear to maintain braking force, then the braking force is maintained, but semi-engagement occurs due to manufacturing tolerances and abrasion, causing the braking force to decrease
Solution Approach 1:
The control device performs a preliminary inspection process before normal operation by temporarily reducing motor current to check if the pawl member is properly engaged with the ratchet gear. This preliminary detection allows the system to identify semi-engagement states before they cause braking force loss, and the control device then adjusts the displacement member position to ensure proper engagement.
2Reliability
If the pawl member is engaged with the ratchet gear to regulate rotation, then the braking force is maintained, but the engagement state cannot be accurately detected, leading to incorrect position determination
Solution Approach 1:
The control device implements a feedback mechanism by performing inspection processes that temporarily reduce motor current and monitor the resulting changes. Based on the detected changes, the control device determines whether the pawl member is properly engaged or in a semi-engagement state, and adjusts the displacement member position accordingly to maintain proper engagement.
3Duration of action of stationary object
If the tip of the pawl member and tip of the tooth are rounded due to manufacturing and abrasion, then the components are more durable, but semi-engagement occurs where the tip of the pawl member engages with the tip of the tooth instead of proper meshing
Solution Approach 1:
The control device changes the operational parameters by temporarily reducing motor current during inspection processes to detect engagement states. By monitoring the changes in motor current and rotation behavior, the control device can distinguish between proper engagement and semi-engagement states caused by rounded tips, and adjust the system to maintain proper engagement geometry.
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 configuration effectively suppresses the occurrence of semi-engagement, ensuring a consistent braking force by accurately determining and correcting the engagement state of the pawl member with the displacement member, thereby maintaining the applied braking force on the wheels.
Implementation Method 1
The solenoid moves the pawl member forward and backward
Implementation Method 2
The friction member applies a braking force to the wheel by being pressed against the rotor
Implementation Method 3
The conversion mechanism converts a rotational motion of the motor into a linear motion and transmits the linear motion to the friction member
Data Source
AI summary
In an electric braking device for a vehicle, the following are carried out in order: a first lock process in which either torque for shifting the ratchet gear in a release direction is generated in an electric motor or the driving of the electric motor is stopped, while a pawl member is being pressed against a ratchet gear; a second lock process in which the rotational angle of the ratchet gear is brought to an angle different from a semi-engaging rotational angle by driving the electric motor; and a third lock process in which the ratchet gear is rotated in the release direction by driving the electric motor in reverse.