Variable Crank Radius Breech Drive Mechanism
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Solution Overview
Problem
Existing drive mechanisms for breech block linear feeding in automatic cannons, particularly electrically powered ones, face challenges in efficiently converting rotary motion into oscillating motion with minimal inertia forces and jerk, while maintaining high cadence and reducing mechanical wear.
Innovation Solution
A cross-slide crank mechanism is employed, where the crank radius changes as it rotates, driven by a motor, and a cam guides the connecting rod radially to achieve smooth forward and backward breech movement, allowing the closure to remain idle in end positions with defined waiting times, using rollers and a cam structure to optimize movement profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a traditional crank mechanism is used to convert rotary motion to oscillating motion, then the breech block can be fed linearly, but high acceleration causes large inertia forces and mechanical wear
Solution Approach 1:
The patent applies the dynamics principle by making the crank radius variable rather than fixed. The crank radius changes continuously during rotation, allowing optimization of the motion profile to reduce acceleration peaks and inertia forces while maintaining high cadence capability
Solution Approach 2:
The invention changes the geometric parameter of the crank radius from a constant value to a variable value that changes with crank angle. This parameter change enables smooth motion control, reducing jerk and inertia forces while maintaining productivity
2Device complexity
If the crank radius is kept constant during rotation, then the mechanism is simpler, but it produces jerky motion with high acceleration and mechanical impact
Solution Approach 1:
The mechanism transitions from a static crank radius to a dynamic, variable crank radius that adjusts during rotation. This dynamic adjustment smooths the motion output, eliminating jerky movements and mechanical impacts while maintaining structural feasibility
Solution Approach 2:
The variable crank radius creates a curved, non-circular motion path that optimizes the acceleration profile. This curved geometry naturally reduces peaks in acceleration and jerk, eliminating harmful mechanical impacts
3Loss of time
If the breech block moves continuously without idle time, then the cycle time is reduced, but the closure cannot remain stationary in end positions for loading and firing operations
Solution Approach 1:
The mechanism employs periodic action by incorporating deliberate idle periods at the end positions within the continuous rotation cycle. The variable crank radius ensures smooth transitions into and out of these stationary phases, maintaining operational requirements while minimizing overall cycle time
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 reduces drive power consumption, minimizes braking power during emergency stops, and allows for higher operational cadence with reduced mechanical wear and jerk, ensuring smooth operation and efficient breech movement.
Implementation Method 1
a cam (15) guides the crank pin (9) radially so that the connecting rod (11) can be moved radially relative to the crank (8)
Implementation Method 2
Two rollers, for example, are arranged on the crank pin and run in cams in the weapon or crankcase
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a mechanism or drive (100) for a weapon, wherein the rotational motion of a motor (2) and the like is converted to a forward or reverse motion of the breech (3) in a simple manner using the Scotch yoke (8) principle. In order to allow the rest periods of the breech (3) in the end positions, the yoke radius is defined by a control cam (15) which however changes when the yoke (8) is rotated. The hinge pin of the yoke (8) is for example externally driven via a pinion shaft (14). A yoke pin (9) is arranged in a groove (17) of the yoke (8) so as to be radially displaceable and carries the breech carrier (5) or the breech (3) in a groove (16) extending at a right angle to the direction of fire via a sliding block (11). Two elements (10), for example rollers, are arranged on the yoke pin (9) and run in control cams (15) in the weapon or yoke housing. The control cam (15) is subdivided into different sectors/sections thereby achieving the desired motion of the breech (3).