Geared Motor Sliding Mount for Headrest Thermal Compensation
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Solution Overview
Problem
Motor vehicle seat headrests with integrated electric motors experience positional variations due to temperature-induced dimensional changes in the plastic housing, leading to non-repeatable operation and potential safety risks during head impacts, as well as parasitic noises during adjustment.
Innovation Solution
A geared motor is coupled with a speed reducer and mounted within the headrest box, allowing it to slide and maintain its nominal position relative to the drive part, decoupled from the housing's dimensional variations, and actuated by spring means to ensure consistent operation and safety by minimizing the motor's impact on energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric motor is mounted integrally with the plastic box, then the device complexity is reduced, but the positioning precision deteriorates due to temperature-induced dimensional variations
Solution Approach 1:
The motor mounting structure is segmented into a fixed mounting plate attached to the frame and a movable motor assembly that can slide independently. This segmentation allows the motor to maintain its nominal position relative to the drive part while being decoupled from the thermal expansions of the plastic box.
Solution Approach 2:
A sliding mechanism acts as an intermediary between the motor and the plastic box, allowing the motor to move independently from the box's dimensional variations. This intermediary structure absorbs the thermal expansion effects while maintaining precise motor positioning.
2Ease of manufacture
If the motor is fixed to the plastic box, then the ease of manufacture is improved, but the reliability deteriorates due to non-repeatable operation under temperature variations
Solution Approach 1:
The motor mounting transitions from a static fixed connection to a dynamic sliding connection. The motor assembly can slide along guide rails or within a slot, allowing it to adapt its position dynamically in response to thermal expansions while maintaining operational reliability.
Solution Approach 2:
The system allows the motor's position parameter to change in response to temperature variations. By permitting controlled movement within a defined range, the system maintains optimal positioning across different thermal conditions, ensuring repeatable operation.
3Device complexity
If the motor is associated with the box, then the device complexity is reduced, but the safety deteriorates due to affected energy absorption behavior during impact
Solution Approach 1:
The motor assembly is extracted from the energy absorption system by providing it with independent movement capability. During impact, the motor can slide away from the impact zone or move independently, preventing it from interfering with the box's energy absorption function and maintaining passenger safety.
Solution Approach 2:
The system is segmented into the energy absorption component (box) and the actuation component (motor). This segmentation allows the box to perform its safety function of absorbing impact energy while the motor remains decoupled and does not compromise this protective function.
4Adaptability or versatility
If the motor positioning varies with temperature, then the adaptability to temperature range is improved, but the operational precision deteriorates due to parasitic noises
Solution Approach 1:
The motor mounting provides dynamic adaptation to temperature changes through controlled sliding movement. The motor can adjust its position within a defined range to accommodate thermal expansions while maintaining precise engagement with the drive part, preventing parasitic noises and ensuring repeatable operation.
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 ensures repeatable and noise-free operation of the head restraint under all conditions, improving passenger safety by decoupling the motor from the energy absorption dynamics during impacts.
Implementation Method 1
it further comprises spring means for actuating said geared motor towards said nominal position
Implementation Method 2
a box made of molded plastic material for absorbing energy in the event of an impact of the head of a passenger on said headrest
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a headrest (1) comprising: a frame for connecting to a seat back; an energy absorption housing (4) movably mounted on said frame so as to be able to be adjusted in height and provided with a front face for receiving the head of a passenger; an electric motor cooperating with at least one drive part (3) integral with said frame, said motor being coupled to a speed reducer so as to form a geared motor (10), said geared motor being mounted in said housing so as to be able to move in translation to maintain its nominal position relative to said drive part independently of dimensional variations of said housing, said headrest further comprising a spring means for actuating said geared motor towards said nominal position.