Spring Brake Cylinder Emergency Release Pawl Mechanism
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Solution Overview
Problem
Existing spring brake cylinders with emergency release devices face issues such as high manufacturing accuracy requirements, large actuation stroke, and potential pawl overload, leading to incomplete disengagement and risk of damage from excessive force.
Innovation Solution
Incorporating spring means connected in parallel to the return spring, which compresses to securely hold the pawl in the disengaged position, reducing the force required for disengagement and preventing accidental engagement with the rotating gear wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pawl is lifted completely out of the gear teeth using a Bowden cable, then the emergency release is achieved, but the actuation stroke becomes large and manufacturing accuracy requirements increase
Solution Approach 1:
The return spring is replaced with a torsion spring mounted on the pawl's rotation axis, transforming the linear displacement problem into a rotational motion problem. This dynamic transformation allows the pawl to rotate into the disengaged position with a smaller effective stroke while maintaining reliable emergency release functionality.
Solution Approach 2:
A lever arm is introduced as an intermediary between the actuating force and the pawl. The lever arm amplifies the actuating force and transforms the motion characteristics, allowing the pawl to be rotated into the disengaged position with a smaller Bowden cable stroke while ensuring complete disengagement from the gear teeth.
2Reliability
If the pawl is lifted far enough to prevent accidental engagement, then safety is improved, but the force required for actuation increases and may overload the pawl
Solution Approach 1:
The torsion spring provides a rotational restoring moment that assists in holding the pawl in the disengaged position. This dynamic spring mechanism reduces the actuating force required compared to a linear spring system, while still ensuring the pawl remains securely disengaged and cannot accidentally re-engage with the gear wheel.
Solution Approach 2:
The problem is solved by transitioning from linear force application to rotational moment application. The torsion spring operates in the rotational dimension, providing a restoring moment that holds the pawl in the disengaged position without requiring excessive linear actuating force, thereby preventing pawl overload while maintaining safety.
3Force
If series-connected springs are used to provide the necessary spring force, then the force requirement is met, but manufacturing accuracy requirements become very high
Solution Approach 1:
The complex series-connected spring system is extracted and replaced with a single torsion spring mounted on the pawl's rotation axis. This simplification eliminates the need for precise matching of multiple springs, reducing manufacturing accuracy requirements while still providing the necessary spring force to hold the pawl in the disengaged position.
Solution Approach 2:
The spring system is transformed by changing from linear compression springs connected in series to a rotational torsion spring. This parameter change allows the spring constant and geometry to be optimized independently, eliminating the need for precise matching of multiple components while achieving the required force characteristics.
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
Ensures reliable and secure locking of the pawl in the disengaged position, preventing damage and ensuring complete disengagement without excessive force, while maintaining manufacturing cost-effectiveness.
Implementation Method 1
spring means (56), which are compressed when the pawl (30) is driven by the driver (40), with this spring force holding the pawl (30) cocked in the gear-disengaged position
Implementation Method 2
an external restoring spring (46) loading the actuating element into its initial position
Data Source
Figure 1~5
Figure 2
Figure 3~4
AI summary
The invention relates to a spring brake cylinder having a housing (4) in which a spring store piston (6) which is loaded by at least one spring store spring (14, 16) and which has a piston rod (24) is axially movable, and having an emergency release device (26) comprising an emergency release actuation device, an emergency release mechanism with a toothed wheel (38) for interrupting the force flow between the spring store piston (6) and piston rod (24), and a holding device (30) which is designed for holding the emergency release device (26) in various holding positions, wherein the holding device has a pawl (30) which can be pivoted relative to the toothed wheel (38) into an engaged and a disengaged position, and the emergency release actuation device has at least one actuation element (42, 44), which is movable relative to the housing (4) and which is loaded into its initial position by restoring spring means (46), and a driver (40), which can be actuated together with the actuation element (44), for driving the pawl (30), in such a way that, upon an actuation of the actuation element (42, 44), the actuation force is transmitted to the driver (40) and from the latter to the pawl (30) in order to transfer the pawl (30) from a position in which it is engaged in relation to the toothed wheel (38) into a disengaged position. The invention provides that spring means (56; 62) are provided between the actuation element (42, 44) and the driver (40) or between the driver (40) and the pawl (30), which spring means are connected in parallel with the restoring spring means (46) and, when the pawl (30) is driven by the driver (40), are compressed in order to generate a spring force which loads the pawl (30) into the position in which it is disengaged from the toothed wheel (48).