Push-push Kinematics for Automotive Flap Actuation
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Solution Overview
Problem
Existing push-push kinematics for automotive fuel tank flaps are costly to manufacture and have limited service life, with complex assembly processes.
Innovation Solution
A simplified push-push kinematics design using a housing, axially displaceable pushbar, rotatable ring, and oblique deflection faces with a minimal component count, allowing for economical production and modular construction, with features like equidistant grooves and protrusions for controlled rotation and locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional push-push kinematics with control wire and cardioid cam is used, then the flap can be actuated, but manufacturing costs are high and service life is limited
Solution Approach 1:
The patent replaces the traditional control wire and cardioid cam mechanical system with a pushrod directly actuating a lever arm. This substitution eliminates the complex wire-cam interaction, reducing manufacturing complexity and cost while improving reliability by removing wear-prone components.
Solution Approach 2:
The invention extracts and removes the control wire and cardioid cam from the system, retaining only the essential pushrod-lever arm mechanism. This extraction simplifies the overall structure, reducing both manufacturing cost and potential failure points, thereby improving service life.
2Ease of operation
If a traditional push-push kinematics with control wire and cardioid cam is used, then the flap can be actuated, but the assembly process is elaborate
Solution Approach 1:
The patent removes the control wire and cardioid cam from the assembly, leaving only the pushrod and lever arm components. This extraction dramatically simplifies the assembly process, reducing the number of parts to be fitted and aligned, thereby improving ease of operation.
Solution Approach 2:
The invention segments the actuation mechanism into distinct functional components: the pushrod for linear actuation and the lever arm for rotational conversion. This clear segmentation allows for independent manufacturing and straightforward assembly, reducing overall device complexity.
3Ease of manufacture
If a simplified push-push kinematics is used, then manufacturing is economical and assembly is simple, but the service life may be compromised
Solution Approach 1:
The patent replaces the complex wire-cam system with a direct pushrod-lever arm mechanical connection. This substitution maintains simplicity for economical manufacturing while actually improving service life by eliminating wear-prone wire and cam surfaces, creating a more durable mechanical linkage.
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
The design reduces manufacturing costs, extends service life, simplifies mechanical geometry, and enables automated installation, while ensuring reliability and compactness, with improved tolerance and ease of assembly.
Implementation Method 1
a spring inside the housing prestressing the pushbar out of the housing
Implementation Method 2
a first deflection face at the pushbar and oblique to its axis, situated between the groove and the drive end, cooperating with the ring's protrusion and rotating said ring by a predetermined angle when said pushbar has been moved by a first predetermined excursion into the housing
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A drive actuating a flap pivotably supported in or on an automobile, in particular actuating a fuel tank flap, comprising a push-push kinematics cooperating with one side of the flap, said push-push kinematics exhibiting the following features: · a housing suitable for integration into an automobile, · a pushbar supported in axially displaceable manner in the housing and which in all its axial positions partly projects through a housing aperture (34) out of the housing and which comprises an external actuating end cooperating the flap, · a spring in the housing prestressing the pushbar to project from the housing, · a rotatable ring which encloses the pushbar and which is supported in the housing in axially fixed manner · at the outside of the pushbar, at least one groove running parallel to its axis and at least one protrusion at the inner circumference of said ring to engage said groove over a wide adjustment range of the pushbar, as a result of which the ring retains its rotational position in said range of the groove when the pushbar is displaced axially, · a first deflection face, running obliquely to the axis of the pushbar, which is configured between the groove and the actuation end and which cooperates with the protrusion of the ring and rotates this ring through a predetermined angle when the pushbar is displaced by a predetermined excursion into the housing · a locking recess pointing toward the actuation end and situated at the pushbar at a circumferential spacing from the first deflection and receiving the protrusion when the pushbar is released following the first excursion, as a result of which the pushbar following a return excursion is locked in a locked position in the housing, · a second deflection face running obliquely to the pushrod axis between the locking recess and the actuation end, cooperating with the protrusion when the pushrod is moved out of the locked position by means of a second excursion farther into the housing, whereby the ring is rotated by a predetermined second angle and the protrusion is aligned with the groove and the pushbar is displaceable into its maximally extended position.