Pedal-Driven Pull Start Assist for Low-Strength Engine Starting
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Solution Overview
Problem
The existing pull start mechanism in power tools requires significant muscular effort from the upper body, which can be a barrier for individuals lacking sufficient strength or those with injuries, particularly in starting engines larger than 10 Hp, and poses a risk during emergencies like power outages.
Innovation Solution
A pull start assist device that converts the pull start into a kick start mechanism, utilizing the stronger muscles of the lower body by engaging a pedal arm and swing arm with a connection link, allowing users to leverage their leg and hip muscles to initiate engine startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional pull start mechanism is used, then the device structure remains simple, but the required upper body muscular strength increases making it inaccessible to some users
Solution Approach 1:
The patent introduces a pedal arm as an intermediary mechanism between the user's foot and the pull start handle. This mediator transforms the user's lower body force into rotational motion that operates the existing pull start mechanism, thereby reducing the direct upper body strength requirement while maintaining compatibility with standard pull start systems.
Solution Approach 2:
Instead of pulling the handle directly with upper body strength, the invention inverts the force application method by using the foot to push down on a pedal. This inversion leverages the stronger lower body muscles to generate the necessary force, which is then transmitted through the pedal arm to rotate the pull start handle in the conventional direction.
2Power
If a kick start mechanism is implemented, then lower body muscle strength is utilized effectively, but the device complexity increases
Solution Approach 1:
The kick start mechanism is segmented into distinct functional components: a pedal arm with pivot axis, a connection link, and a swing arm with handle receiver. This segmentation allows each component to perform a specific function (force application, force transmission, handle manipulation) while maintaining overall system simplicity and ease of assembly.
Solution Approach 2:
The pedal arm assembly serves multiple functions: it acts as a force amplifier, a motion converter (linear to rotational), and a mechanical linkage to the existing pull start system. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while maximizing power utilization.
3Productivity
If the pull start handle displacement is increased, then engine startup effectiveness improves, but the required pedal force increases
Solution Approach 1:
The invention changes the dimension of force application from horizontal pulling (arm level) to vertical pushing (foot level). This dimensional change allows the user to leverage body weight and stronger leg muscles, effectively increasing the available force without requiring proportionally higher pedal force due to the mechanical advantage provided by the pedal arm's lever geometry.
Solution Approach 2:
The pedal arm is designed with specific pivot points and linkages that create dynamic mechanical advantage. As the pedal arm rotates during the kicking motion, the geometry changes to optimize force transmission, allowing effective handle displacement with moderate pedal force throughout the motion range rather than requiring peak force at a single point.
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
Enables users to start engines using more powerful lower body muscles, providing an alternative to traditional pull starting, enhancing accessibility and reducing the risk of injury or failure during engine startup, especially in scenarios where upper body strength is insufficient.
Implementation Method 1
movement of the pedal of the pedal arm of a set displacement may cause a greater displacement of the handle receiver of the swing arm
Implementation Method 2
A return spring may be coupled to the frame and the pedal arm, whereby if the pedal arm is moved, the return spring may return the pedal arm to a starting position
Data Source
AI summary
A pull start assist device may include a frame with a base and a longitudinal member. The longitudinal member may include a first pivot axis and a second pivot axis displaced from the first pivot axis. The device may also include a pedal arm with a pedal on a first end and a second end pivotally coupled to the first pivot axis of the longitudinal member. A swing arm may be provided with a handle receiver on a first end and a second end pivotally coupled to the second pivot axis of the longitudinal member. A connection link maybe used to connect the swing arm and the pedal arm, whereby a pull start handle of a powered tool may be supported by the handle receiver and the pedal displaced by the foot of a user, actuating the swing arm and starting the powered tool.