Segmented Transmission Case for Working Vehicle Assembly
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Solution Overview
Problem
Conventional working vehicles face challenges in assemblability, maintainability, and durability due to the non-closely arranged components in the transmission case, which affects the stability of lubricant oil supply and braking mechanisms, and there is a need for synchronizing the rotation speed of the PTO shaft with vehicle speed during operations like fertilizing and seeding.
Innovation Solution
A working vehicle design with a transmission case divided into three sections - front, intermediate, and rear cases - where the hydraulic continuously variable transmission, traveling transmission gear mechanisms, and differential mechanism are strategically positioned to enhance assemblability, maintainability, and durability, with a lubricant oil pump for stable oil supply and a separate parking brake system for improved braking efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If components in the transmission case are arranged in the conventional configuration (traveling transmission gear mechanism, PTO transmission gear mechanism, and differential gear mechanism disposed in the front portion, and hydraulic continuously variable transmission disposed on the rear side), then the transmission case can accommodate all necessary components, but the components of each transmission system are not closely arranged, resulting in poor assemblability and maintainability
Solution Approach 1:
The transmission case is divided into three separate cases: a first case accommodating the traveling transmission gear mechanism, a second case accommodating the PTO transmission gear mechanism, and a third case accommodating the differential gear mechanism. This segmentation allows each case to be assembled and maintained independently, significantly improving assemblability and maintainability while reducing the complexity of handling a single large integrated case.
2Reliability
If the hydraulic continuously variable transmission is disposed on the rear side adjacent to the differential gear mechanism, then the transmission case can be used as a hydraulic oil tank, but the lubricant oil supply to internal mechanisms becomes unstable
Solution Approach 1:
The transmission case is segmented into three separate cases, each accommodating specific transmission mechanisms. This segmentation allows for optimized lubricant oil supply to each case independently, ensuring stable lubrication to internal mechanisms while maintaining the hydraulic oil tank functionality. The separated structure enables better control over oil circulation and pressure distribution to each transmission system.
3Reliability
If the common brake mechanism is used for both traveling braking and parking braking, then the brake system structure is simplified, but the durability of the brake mechanism deteriorates due to excessive usage
Solution Approach 1:
The brake system is divided into two separate brake mechanisms: a first brake mechanism dedicated to traveling braking operations and a second brake mechanism dedicated to parking braking operations. This segmentation prevents the overuse of a single brake mechanism, thereby improving durability. Although this increases the number of parts, each brake mechanism can be optimized for its specific function and maintained independently.
Solution Approach 2:
The brake system is designed with universal functionality distributed across two specialized mechanisms. The first brake mechanism handles traveling braking while the second handles parking braking, allowing each mechanism to be optimized for its specific operational requirements while collectively providing complete braking coverage for both traveling and parking states.
4Adaptability or versatility
If the PTO shaft rotation speed is maintained at constant speed directly from the engine, then the engine operation is simplified, but the rotation speed cannot be synchronized with vehicle speed during fertilizing and seeding operations
Solution Approach 1:
The PTO transmission system is separated into an independent second case that houses the PTO transmission gear mechanism. This segmentation allows the PTO shaft rotation speed to be controlled independently from the engine speed, enabling speed synchronization with vehicle speed during operations like fertilizing and seeding, while the engine can continue to operate at optimal speeds.
Solution Approach 2:
The PTO transmission gear mechanism in the second case provides dynamic speed adjustment capability, allowing the PTO shaft rotation speed to be synchronized with vehicle speed during fertilizing and seeding operations. This dynamic control is achieved through the gear mechanism while maintaining engine operation independence.
Data Source
AI summary
A working vehicle includes: an engine mounted on a traveling machine body; a hydraulic continuously variable transmission configured to shift driving force from the engine; a transmission case incorporating the hydraulic continuously variable transmission; and rear traveling units disposed on both left and right sides of the transmission case via rear axle cases. The transmission case is divided into three sections of a front case, an intermediate case, and a rear case. The left and right rear axle cases are attached to both left and right sides of the rear case. The intermediate case, coupling the front case to the rear case, is coupled to left and right vehicle body frames forming the traveling machine body.