Vehicle HUD Stopper Gear Torque Limiting Mechanism
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Solution Overview
Problem
Conventional head-up display (HUD) devices for vehicles face issues with excessive torque application to gears, leading to potential damage and reliability concerns due to the design of the reduction gear mechanism, where the last gear experiences the greatest torque, and the occupant cannot determine if the device is faulty when image display does not change despite continued adjustment commands.
Innovation Solution
The HUD device incorporates a reduction gear mechanism with a stopper gear and a stopper-adjacent gear, where the stopper gear has a partial gear portion with gear teeth arranged in less than 360 degrees, limiting the rotation angle of the reflecting mirror to a predetermined adjustable range, ensuring the torque is within the strength design value and preventing excessive torque application, thus enhancing durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a reduction gear mechanism is employed to amplify and transmit torque from the motor to the reflecting mirror, then the installation space for the motor is reduced, but excessive torque is applied to the gears leading to potential damage
Solution Approach 1:
The stopper gear is designed with a partial gear portion (less than 360 degrees of gear teeth) that engages with the stopper-adjacent gear before the last gear completes its full rotation. This preliminary engagement limits the torque transmission path and prevents excessive torque from being applied to the gears, thereby protecting the gear strength while maintaining the compact reduction gear mechanism
Solution Approach 2:
The gear mechanism is segmented into distinct functional portions: the stopper gear with a partial gear portion (less than 360 degrees), the stopper-adjacent gear, and the last gear. This segmentation allows the stopper gear to independently control the rotation range and limit torque application, while the last gear focuses on driving the reflecting mirror, thus resolving the contradiction between compact space and gear strength protection
2Volume of moving object
If the last gear includes a partial gear portion with less than 360 degrees of gear teeth, then the installation space is reduced, but the occupant cannot determine whether the device is at fault when image display does not change
Solution Approach 1:
The stopper gear with its partial gear portion performs the preliminary action of limiting rotation before the last gear operates. This design provides a predetermined adjustable range that includes the displayable range, ensuring that the reflecting mirror can be positioned correctly for image display while preventing over-rotation. The clear mechanical stopper mechanism provides tactile and visual feedback to the occupant, improving reliability perception
Solution Approach 2:
The stopper gear acts as an intermediary between the motor and the last gear, mediating the torque transmission and rotation control. This intermediary mechanism provides a reliable, predetermined rotation limit that ensures the reflecting mirror reaches the correct position for image display, giving the occupant confidence that the device is functioning properly
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 configuration ensures that the torque generated by the motor is effectively limited within the strength allowance, preventing gear damage and maintaining the occupant's sense of reliability by ensuring the virtual image display changes within the adjustable range, thereby improving the durability and reliability of the HUD device.
Implementation Method 1
The optical system includes a reflecting mirror, which is disposed rotatably relative to the display to reflect the image displayed by the display
Data Source
AI summary
A head up display device includes a display, an optical system having a reflecting mirror, a motor, and a reduction gear mechanism having gears in engagement with each other. A stopper gear is further on a preceding side than the last gear in the mechanism. The stopper gear includes a partial gear portion having teeth arranged in a region of the stopper gear in a range of less than 360 degrees in its rotational direction. Rotation of the stopper gear is stopped by engagement of both-end teeth of the partial gear portion with a stopper-adjacent gear, so a range of a rotation angle of the mirror is limited to a predetermined adjustable range, which includes a displayable range. The angle between an adjustable range lower limit and displayable range lower limit, and the angle between an adjustable range upper limit and displayable range upper limit are larger than 0 degree.