Variable Steering Ratio for Personal Watercraft
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Solution Overview
Problem
Conventional personal watercraft with push-pull cable systems have a constant steering ratio across all speeds, leading to differing steering loads at higher and lower speeds, and require straight routing of cables, limiting space for other components due to inability to bend around corners.
Innovation Solution
Incorporating a control device and actuator connected to a steering handle unit and speed sensor to dynamically adjust the steering nozzle's angle based on detected steering and speed inputs, allowing for variable steering ratios and reduced mechanical constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a push-pull cable system is used to connect the steering handle unit and steering nozzle, then the steering mechanism is simple and reliable, but the steering ratio cannot be adjusted for varying speeds and the cables require straight routing which limits space utilization
Solution Approach 1:
The patent applies dynamics by making the steering ratio adjustable based on operating conditions. The control device dynamically changes the steering ratio according to the running speed detected by the speed sensor, allowing the actuator to pivot the steering nozzle by different angles relative to the steering handle unit's operation angle depending on whether the watercraft is moving at high or low speed. This resolves the contradiction by enabling adaptability without requiring a completely complex manual adjustment mechanism.
Solution Approach 2:
The patent replaces the direct mechanical connection of push-pull cables with an electronic control system. Instead of mechanically linking the steering handle unit directly to the steering nozzle through cables that require straight routing, the system uses sensors, a control device, and an actuator to achieve steering control. This substitution eliminates the space constraints imposed by cable routing while enabling dynamic steering ratio adjustment.
2Reliability
If push-pull cables are laid in a straight route, then the cable system works reliably, but space for positioning other devices or components is limited
Solution Approach 1:
The patent replaces the mechanical push-pull cable system with an electronic control system consisting of sensors, a control device, and an actuator. This substitution eliminates the need for physical cables that require straight routing, thereby freeing up space in the engine room for other components while maintaining reliable steering control through electronic signaling and actuation.
3Ease of operation
If the steering ratio is kept constant for all speeds, then the steering mechanism is simple, but the steering loads become excessively high at higher speeds
Solution Approach 1:
The patent applies dynamics by implementing a variable steering ratio that changes with running speed. At higher speeds, the control device adjusts the steering ratio so that a given operation angle of the steering handle unit produces a smaller pivot angle of the steering nozzle, thereby reducing the steering load and making the system easier to operate. At lower speeds, a larger steering ratio can be used for more responsive steering. This dynamic adjustment directly addresses the contradiction between operational ease and force requirements.
Data Source
AI summary
A personal watercraft can have a steering nozzle pivoting in accordance with the operation of a steering handle unit to change the traveling direction of a vehicle body. A steering position sensor can be configured to detect the steering angle of the steering handle unit. An actuator can be arranged to pivot the steering nozzle to change the steered angle thereof. A running speed sensor can be configured to detect the running speed of the vehicle body, and a control device. The control device can determine an operational amount of the actuator and control the actuator based upon the detection amount of the steering position sensor, the running speed sensor, and a steering ratio preset with reference to the steering angle and the running speed. The steering ratio is set to be smaller as the running speed becomes larger.