Gearbox Switching Device Dual Guide Bore
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Solution Overview
Problem
Existing transmission shifting devices in agricultural vehicles, such as combine harvesters, face issues with compactness due to large installation space requirements and high bending loads on shifting forks and actuating rods, leading to friction losses and wear.
Innovation Solution
A transmission design with a second guide bore parallel to the first guide bore, supporting the shift fork with both the actuating rod and a guide rod, minimizing installation space and reducing bending moments, while using spring elements to maintain shifting positions in case of actuator failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the switching fork is positioned between guide bores to minimize switching torque, then the bending moment on the actuating rod is reduced, but the installation space increases and compactness is compromised
Solution Approach 1:
The patent moves the second guide bore from the opposite housing half (requiring greater axial distance) to the same housing half (utilizing radial space). This dimensional reconfiguration allows the actuating rod to be supported by both guide bores within the same housing section, minimizing the axial installation space while maintaining the torque-minimizing geometry of having the switching fork positioned between the guide bores.
2Device complexity
If the switching fork is connected to the actuating rod at only one outer point, then the structure is simplified, but high bending loads act on the switching fork and actuating rod
Solution Approach 1:
The patent introduces a second connection point between the switching fork and actuating rod by providing a second guide bore with a guide rod in the same housing half. This creates a dual-supported structure where the switching fork is connected to the actuating rod at two locations, locally enhancing the structural rigidity and reducing bending moments without significantly increasing overall device complexity.
3Ease of manufacture
If the shift fork has rotational play relative to the actuating rod, then the connection is more tolerant of manufacturing variations, but friction losses increase and wear occurs
Solution Approach 1:
The patent employs two guide bores with corresponding guide rods that constrain the actuating rod and switching fork assembly. This dual-guidance arrangement creates homogeneous constraint conditions along the length of the actuating rod, eliminating rotational play by providing symmetric radial support at two locations. The result is reduced friction losses and wear while maintaining manufacturing tolerability through the distributed constraint system.
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 design achieves a more compact transmission with reduced wear and friction, ensuring reliable shifting operations even if the hydraulic system fails, by supporting the shift fork concentrically and providing an additional connection point to minimize bending moments.
Implementation Method 1
spring elements to maintain shifting positions in case of actuator failure
Data Source
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AI summary
A switching device (50) for a transmission (24) with a first and a second transmission housing part (28, 30) is proposed. The switching device (50) comprises a shift sleeve (52), a shift fork (54) engaging in the shift sleeve (52), an actuator (56) arranged in the first transmission housing part (28), and an actuating rod (58) connected at one end to the actuating actuator (56) and at the other end to the shift fork (54), wherein the actuating rod (58) is mounted in a first guide bore (60) formed in the first transmission housing part (28). It is proposed that a second guide bore (62) be formed in the first gearbox housing part (28) parallel to the first guide bore (60) and that a guide rod (63) aligned parallel to the actuating rod (58) be provided, which is connected at one end to the shift fork (54) and is supported at the other end in the second guide bore (62).Furthermore, a transmission (50) with such a switching device is proposed.