Transmission Parking Lock Control on Inclines Without Roll Damage
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Solution Overview
Problem
Existing methods for controlling the engagement and disengagement of a vehicle's parking lock in a transmission are not optimally designed, leading to potential damage and discomfort due to the parking lock mechanism being subjected to rolling and increased effort required for release, especially on inclined roads.
Innovation Solution
The method determines the current road gradient and vehicle inclination to decide whether the activated parking brake can be deactivated, preventing the parking lock from rolling and becoming distorted by only allowing deactivation when the vehicle is on a gentle slope and ensuring the parking lock is engaged before releasing the brake, and automatically engaging the parking lock when the vehicle stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the parking brake is activated to further decelerate the vehicle before engaging the parking lock, then the vehicle speed is reduced below the threshold, but the vehicle may roll into the already engaged parking lock on inclined roads causing damage and distortion
Solution Approach 1:
The control unit checks the vehicle speed and only allows parking brake deactivation when the vehicle has come to a complete standstill (speed = 0 km/h). This preliminary check ensures the vehicle is stationary before the parking lock is engaged, preventing the vehicle from rolling into the locking mechanism on inclined roads.
Solution Approach 2:
The control unit continuously monitors the vehicle speed via the speed sensor and uses this feedback to control the deactivation of the parking brake. The system only permits brake deactivation when the feedback indicates zero speed, creating a closed-loop control that prevents premature disengagement on slopes.
2Reliability
If the parking lock is engaged while the vehicle is still moving, then the vehicle can be secured against rolling, but the parking lock mechanism may become distorted and require greater force for release
Solution Approach 1:
The control unit performs a preliminary check of the vehicle speed before allowing the parking lock to be engaged. It only permits engagement when the vehicle has come to a complete standstill, ensuring the locking mechanism engages a stationary vehicle rather than one that is rolling, thereby preventing distortion and excessive release force.
Solution Approach 2:
The control unit prevents the parking lock engagement action until the vehicle speed is zero. This preliminary anti-action blocks the engagement command when conditions are not met (vehicle still moving), avoiding the harmful effect of engaging a moving vehicle that would cause mechanism distortion.
3Ease of operation
If the parking brake is deactivated on a steep incline before the parking lock is engaged, then the driver has full control, but the vehicle may roll into the engaged parking lock causing damage
Solution Approach 1:
The control unit uses feedback from the speed sensor to determine when it is safe to deactivate the parking brake. It only permits deactivation when the feedback shows the vehicle is stationary, preventing the driver from accidentally deactivating the brake on a slope before the parking lock is engaged, thus avoiding vehicle rolling and damage.
Solution Approach 2:
The control unit acts as an intermediary between the driver's deactivation request and the actual parking brake release. It mediates by checking the vehicle speed first and only allowing deactivation when conditions are safe, preventing direct driver control that could lead to harmful rolling on inclines.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for controlling the engagement and/or disengagement of a parking lock (1) of a transmission (2) of a vehicle (3), in particular of a motor vehicle (3a), wherein the vehicle (3) has the parking lock (1), a parking brake (4) and a control unit (5), wherein the parking lock (1) can be actively engaged or disengaged in and/or on the transmission (2), in particular in an automatic transmission (2a), wherein, for the ascertainment of a driver demand, specifically to secure the vehicle (3) against rolling away and/or against onward travel, the vehicle (3) has at least one device (6) for activating the parking lock (1), in particular a parking lock button (6a) and/or a particular positioning capability for a selector lever, and at least one device (7) for activating the parking brake (4), in particular at least one parking brake button (7a) (EPB button), wherein the control of the active engagement and disengagement of the parking lock (1) in or on the transmission (2) is controlled by means of the control unit (5), wherein at least one present determined first driving parameter (v) is transmitted to the control unit (5) and/or is ascertained by the control unit (5), but in particular the control unit (5) ascertains present values of multiple determined driving parameters, wherein, as a determined first driving parameter, at least the present vehicle speed (v) of the vehicle (3) is ascertained and/or calculated when the driver has actuated the device (6) for activating the parking lock (1), wherein, however, the parking lock (1) is actively engaged in or on the transmission (2) only when the vehicle (3) is at a standstill and/or the present driving speed (v) is substantially zero, and wherein, if the vehicle (3) has, however, not yet reached its standstill and the present vehicle speed (v) exceeds a determined vehicle speed threshold value, the active engagement of the parking lock (1) in or on the transmission (2) is prevented, and/or, if the vehicle (3) has not yet reached its standstill and the present vehicle speed (v) falls below a determined vehicle speed threshold value, then the vehicle (3) initially continues to be braked by means of the then automatically activated parking brake (4) until the standstill is reached and/or until the driving speed of said vehicle has reached substantially zero. Driving comfort is increased by virtue of the fact that, as a second driving parameter, the present gradient (s) of the roadway and/or the longitudinal inclination of the vehicle is ascertained and/or calculated, and that, on the basis of the ascertained gradient value and/or the ascertained longitudinal inclination value of the vehicle (3), it is decided and/or checked whether a hydraulic brake system (8) of the vehicle (3) is activated. Furthermore, driving comfort is increased by virtue of the fact that, as a second driving parameter, the present gradient (s) of the roadway and/or the longitudinal inclination of the vehicle (3) is ascertained and/or calculated, and that, on the basis of the ascertained gradient value and/or the ascertained longitudinal inclination value of the vehicle (3), it is decided and/or checked whether an already automatically activated parking brake (4) is deactivatable again by the driver.