Cam Mechanism Clutch Actuation for Drag Torque Reduction
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Solution Overview
Problem
Conventional driving force transmission apparatuses in four-wheel-drive vehicles experience adverse effects such as reduced turning performance and fuel economy due to drag torque, which occurs between clutch plates due to lubricating oil viscosity, leading to inefficient clutch action when shifting from two-wheel-drive to four-wheel-drive mode.
Innovation Solution
A driving force transmission apparatus incorporating a first cam mechanism that converts rotational force into clutch force for the main clutch and a second cam mechanism that reduces the interval between clutch plates, utilizing an input cam member and an output cam member to generate cam thrust forces, thereby improving clutch response and reducing drag torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clearance between adjacent two clutch plates of the main clutch is increased to suppress drag torque, then fuel economy and turning performance are improved, but the response of clutch action decreases
Solution Approach 1:
The second cam mechanism is activated before the first cam mechanism to preliminarily reduce the clearance between clutch plates. This preliminary action ensures that when clutch engagement is required, the plates are already in close proximity, enabling rapid response without requiring excessive clearance for drag torque suppression.
Solution Approach 2:
The invention dynamically adjusts the clearance between clutch plates using two cam mechanisms that can change the spacing based on operational requirements. The second cam mechanism provides dynamic preliminary adjustment, while the first cam mechanism provides the main engagement action, allowing the system to optimize both drag torque reduction and response speed.
2Object-affected harmful factors
If the clearance between adjacent two clutch plates is increased to reduce drag torque, then turning performance is improved, but the clutch action response decreases
Solution Approach 1:
The second cam mechanism performs preliminary action by reducing the clearance between clutch plates before the main engagement occurs. This preliminary reduction of spacing minimizes drag torque during idle operation while ensuring rapid response when engagement is needed, as the plates are already positioned close to each other.
Solution Approach 2:
The clutch adjustment function is segmented into two distinct cam mechanisms: the second cam mechanism handles preliminary clearance reduction, and the first cam mechanism handles the main engagement. This segmentation allows each mechanism to be optimized for its specific function, reducing drag torque while maintaining fast response.
3Device complexity
If a single cam mechanism is used to convert rotational force into clutch force, then the device complexity is reduced, but the clutch action response and drag torque reduction are insufficient
Solution Approach 1:
The cam mechanism is segmented into two distinct components: the second cam mechanism for preliminary clearance reduction and the first cam mechanism for main engagement force application. This segmentation enables the system to achieve fast response and effective drag torque reduction while keeping each individual cam mechanism relatively simple in structure.
Solution Approach 2:
The second cam mechanism performs preliminary action by reducing clearance before the first cam mechanism applies the main engagement force. This two-stage approach improves response speed and drag torque control without requiring either cam mechanism to be overly complex, as each handles a specific portion of the engagement process.
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
The solution effectively reduces drag torque and enhances the response of the main clutch action, improving the overall efficiency and performance during mode shifts, while also ensuring proper lubrication through pumping action.
Implementation Method 1
The electromagnetic clutch is configured to generate electromagnetic force to drive the pilot clutch.
Implementation Method 2
The cam mechanism has a pushing portion that applies pushing force to the main clutch through cam action caused by the rotational force from the first rotary member.
Implementation Method 3
The main clutch is configured such that the inner clutch plates and the outer clutch plates frictionally engage with each other to couple the first rotary member and the second rotary member to each other so that torque is transmittable therebetween.
Implementation Method 4
drag torque that occurs on the basis of the viscosity of the lubricating oil between the inner clutch plates and the outer clutch plates of the pilot clutch
Data Source
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AI summary
A driving force transmission apparatus (1) includes: a first cam mechanism (15) that converts rotational force from a housing (12) into first cam thrust force (P1) used as clutch force of a main clutch (8) when the first cam mechanism (15) is actuated through clutch action of a pilot clutch (10); and a second cam mechanism (16) that is actuated prior to conversion of the rotational force into the first cam thrust force by the first cam mechanism (15), and that generates second cam thrust force (P2) for reducing an interval between clutch plates of the main clutch (8). The second cam mechanism (16) includes an input cam member (160) that rotates upon receiving rotational force used as actuating force of the input cam member (160) from a cam actuating driving source (5), and an output cam member (161) that generates the second cam thrust force (P2) between the output cam member (161) and the input cam member (160) and outputs the second cam thrust force (P2).