Automotive Clutch Unit Brake-Side Outer Race Design
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Solution Overview
Problem
Conventional clutch units face limitations in producing a brake-side outer race with sufficient thickness and strength, leading to reduced breaking torque and increased elastic deformation, which complicates the integration of a clutch unit into an automobile seat-lifter section while maintaining cost-effectiveness.
Innovation Solution
The clutch unit design incorporates a brake-side outer race formed by punching a thick plate-like member, allowing for improved strength and reduced elastic deformation, and eliminates the need for thermal treatment on the cover by having claw portions of the lever-side outer race slide on the brake-side outer race, thereby reducing costs and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the brake-side outer race is formed by press working of a single plate-like material into a cup-shaped configuration, then the manufacturing process is simple, but the thickness of the plate-like material is limited and the strength is reduced
Solution Approach 1:
The brake-side outer race is divided into two separate components: a cup-shaped outer race formed by press working and a cover formed by punching a thick plate-like member. These two segments are then assembled together, allowing each component to be optimized for its specific manufacturing process while achieving overall structural strength.
Solution Approach 2:
The brake-side outer race assembly combines two different structural forms (press-formed cup shape and punched thick plate) into a composite structure. The cover made from thick plate-like material provides enhanced strength and rigidity to the overall brake-side outer race assembly.
2Ease of manufacture
If the plate-like material thickness is reduced to enable cup-shaped press working, then the component can be manufactured, but the breaking torque decreases and elastic deformation increases
Solution Approach 1:
The structure is segmented into a thin-walled cup-shaped outer race (optimized for formability) and a thick-plate cover (optimized for strength). This segmentation allows the thin cup to be formed by press working while the thick cover provides the necessary breaking torque and minimizes elastic deformation.
Solution Approach 2:
Different parts of the brake-side outer race assembly have different thicknesses and material properties. The cup-shaped portion uses thinner material for ease of forming, while the cover uses thick plate-like material for high strength and low elastic deformation, creating local quality variations optimized for different functional requirements.
3Ease of manufacture
If claw portions slide on the end surface of the cover, then thermal treatment on the cover is unnecessary, but the structure requires precise positioning
Solution Approach 1:
The sliding contact function is extracted from the cover end surface and transferred to the brake-side outer race end surface. This extraction eliminates the need for thermal treatment on the cover while maintaining the necessary sliding contact functionality, as the claw portions now slide on the brake-side outer race instead.
Solution Approach 2:
The brake-side outer race serves as an intermediary surface between the claw portions and the cover assembly. By providing a sliding surface on the brake-side outer race end surface, it mediates the contact interaction, eliminating the need for thermal treatment on the cover while ensuring precise positioning through the intermediary surface.
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 enhances the strength and breaking torque of the brake-side clutch portion, reduces the axial dimension of the clutch unit, and lowers production costs by eliminating unnecessary thermal treatment, resulting in a more reliable and compact clutch unit suitable for automobile seat-lifter applications.
Implementation Method 1
an inner centering spring (118) serving as a first elastic member which is provided between the retainer (117) and the brake-side outer race (123) and accumulates elastic force with torque input from the lever-side outer race (114), restoring the retainer (117) to the neutral state with the accumulated elastic force through releasing the input torque
Implementation Method 2
an outer centering spring (119) serving as a second elastic member which is provided between the lever-side outer race (114) and the brake-side outer race (123) and accumulates elastic force with torque input from the lever-side outer race (114), restoring the lever-side outer race (114) to the neutral state with the accumulated elastic force through releasing of the input torque
Implementation Method 3
a plurality of plate springs (28) each arranged between the cylindrical rollers (27) of each pair, for imparting repulsive force to the cylindrical rollers (27) through elastic deformation
Data Source
Figure 1
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Figure 3
AI summary
To secure abrasion resistances of a brake-side outer race and a stopper contact portion, and to reduce cost, there is provided a clutch unit including: a lever-side clutch portion for controlling transmission/interruption of rotational torque to an output side with lever operation; a brake-side clutch portion for transmitting torque input from the lever-side clutch portion to the output side and for interrupting torque reverse-input from the output side, in which: the lever-side clutch portion includes an input-side member to which torque is input with the lever operation; claw portions (14g) extending in an axial direction are provided on an outer periphery of the lever-side outer race (14) of the input-side member; the brake-side clutch portion includes a stationary-side member restricted in rotation, the stationary-side member being constituted by a brake-side outer race (23) arranged while being separated from the lever-side outer race (14) in the axial direction and a cover (24) attached to the brake-side outer race (23) on a lever-side outer race (14) side thereof; claw portions (14g) of the lever-side outer race (14) are brought into slidable contact with an end surface of the brake-side outer race (23) with rotation of the lever-side outer race (14), the rotation being effected with lever operation; and the claw portions (14g) of the lever-side outer race (14) are allowed to come into contact, in a rotational direction, with lock portions (24e, 24f) provided on an outer periphery of the cover (24).