CVT Dry Belt Engine Unit Heat Management
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Solution Overview
Problem
The existing electronically-controlled continuously variable transmission apparatuses employing dry belts in engine units face challenges in reducing fuel consumption and preventing dry belt degradation due to mechanical losses and heat exposure.
Innovation Solution
The solution involves relocating the rotational force conversion mechanism to the lubrication space within the crankcase member, reducing the number of sealing members, and positioning it away from the hot crank web to minimize heat transfer, thus reducing mechanical losses and heat-induced degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotational force conversion mechanism is provided in the dry space with a dedicated lubrication chamber isolated from the dry space, then the conversion contact portion can be lubricated, but sealing members are required which generate friction and increase mechanical loss
Solution Approach 1:
The patent merges the lubrication space for the conversion contact portion with the crankcase lubrication space, eliminating the need for a separate dedicated lubrication chamber. This integration removes the sealing members that would be required to isolate separate lubrication spaces, thereby reducing friction and mechanical loss while still providing necessary lubrication to the conversion contact portion.
Solution Approach 2:
The crankcase lubrication space is made multi-functional by allowing it to serve both as the general crankcase lubrication space and as the lubrication space for the conversion contact portion of the rotational force conversion mechanism. This universal use of the lubrication space eliminates the need for additional sealing components and reduces mechanical loss.
2Device complexity
If the rotational force conversion mechanism is positioned close to the crankshaft member for compact design, then device complexity is reduced, but the dry belt is exposed to high temperature causing deterioration
Solution Approach 1:
The patent segments the transmission apparatus into distinct thermal zones by positioning the dry belt in the dry space away from the hot crankshaft area, while placing the rotational force conversion mechanism in the lubrication space where it can access lubrication without exposing the dry belt to high temperatures. This spatial segmentation protects the heat-sensitive dry belt while maintaining compact overall design.
Solution Approach 2:
The lubrication space acts as an intermediary zone between the hot crankshaft area and the dry space containing the belt. The rotational force conversion mechanism is positioned in this intermediary lubrication space, allowing it to be close to the crankshaft for compact design while the dry belt remains protected in the cooler dry space.
3Reliability
If multiple sealing members are provided to isolate the dedicated lubrication chamber, then lubrication is maintained, but friction increases and fuel consumption deteriorates
Solution Approach 1:
The patent combines the conversion contact portion lubrication space with the crankcase lubrication space into a single unified lubrication system. This merging eliminates the need for multiple sealing members to isolate separate lubrication chambers, reducing friction losses and improving fuel consumption while maintaining reliable lubrication through the shared lubricant supply.
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 arrangement improves fuel efficiency by reducing mechanical losses and prevents dry belt degradation while maintaining the transmission efficiency and durability of the engine unit.
Implementation Method 1
a conversion contact portion where the rotating member and the relative moving member contact each other, being provided in the lubrication space formed by the crankcase member so as to be exposed to the lubrication space
Implementation Method 2
The dry belt is wound onto the primary pulley and the secondary pulley. The primary pulley rotates as a rotational force of the crankshaft is transmitted thereto. The secondary pulley rotates in accordance with the primary pulley so as to transmit the rotational force to a rear wheel.
Data Source
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AI summary
An engine unit including an electronically-controlled continuously variable transmission apparatus (30) employing a dry belt (32), in which the fuel consumption of the engine unit is improved while degradation of the dry belt (32) by heat is prevented, is provided. In the electronically-controlled continuously variable transmission apparatus (30) including the engine unit indicated by (a), a rotational force conversion mechanism (72) is provided not to overlap the rotation range (CW) of a crank web (21a) when viewed in any direction orthogonal to a crank rotational axis Ac. A conversion contact portion (70) where a relative moving member (73) is in contact with a rotating member (74) is provided in a lubrication space (22c) formed by a crankcase member (22) so as to be exposed to the lubrication space (22c). In the electronically-controlled continuously variable transmission apparatus (30), two sealing members (22d, 44d) are provided. In an electronically-controlled continuously variable transmission apparatus (100) of Comparative Example (b), 10 sealing members (103, 107, 112a, 114, 116a, 122b, 122b, 126b, 126b, 107a) are provided.