Twist Grip Throttle Assembly for Precise Weed Trimmer Speed Control
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Solution Overview
Problem
Prior art weed trimmers face issues with fine motor speed adjustment due to short plastic trigger travel, vulnerability to damage during transport, operator fatigue from trigger configuration, and difficult throttle cable replacement.
Innovation Solution
A twist grip throttle assembly replaces the traditional trigger, featuring a rotatably mounted tubular member with vibration dampening ridges, allowing for more sensitive power control and a natural operating position, and includes a split collar and on-off switch for improved usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional plastic trigger is used for throttle control, then the device structure is simple, but fine motor speed adjustment is difficult due to short trigger travel
Solution Approach 1:
The patent transforms the static trigger pull mechanism into a dynamic rotary twist grip mechanism. The rotary motion provides continuous variable control through a larger range of movement, enabling fine motor speed adjustment. The twist grip rotates within a throttle tube, converting rotational displacement into proportional throttle cable actuation for precise speed control.
Solution Approach 2:
The patent transitions from linear trigger pull (one-dimensional motion) to rotary twist grip (two-dimensional rotational motion). This dimensional change provides a larger control range and finer resolution for speed adjustment, as the rotary motion allows for gradual progression through multiple degrees of rotation rather than a single linear pull.
2Reliability
If a traditional plastic trigger is used, then manufacturing is simple, but the trigger is vulnerable to damage during transport
Solution Approach 1:
The throttle assembly is divided into separate modular components: the throttle tube, twist grip, spring mechanism, and cable attachment points. This segmentation allows each component to be manufactured independently using appropriate processes, then assembled together. The modular design improves durability by allowing replacement of damaged parts without replacing the entire assembly.
Solution Approach 2:
The patent employs composite construction with the twist grip and throttle tube made from durable materials resistant to transport damage. The assembly combines metallic and polymer components to achieve both strength and flexibility, improving reliability while maintaining manufacturability through standard material selection.
3Ease of operation
If a traditional trigger configuration is used, then the structure is simple, but operator fatigue increases due to awkward hand and arm position
Solution Approach 1:
The rotary twist grip allows the operator's hand to rotate naturally along the handle axis, maintaining a more ergonomic forearm position compared to the wrist-flexing trigger pull. This dynamic rotational motion reduces static muscle tension and improves operational comfort during extended use.
Solution Approach 2:
The patent changes the control parameter from linear displacement (trigger pull distance) to angular displacement (twist grip rotation angle). This parameter change allows for finer control resolution and reduces the physical effort required, as rotational motion is more naturally accommodated by the human arm and hand mechanics.
4Ease of repair
If a traditional trigger assembly is used, then cable replacement is difficult, but the trigger provides adequate control
Solution Approach 1:
The modular segmented design includes discrete attachment points for the throttle cable at both the grip and engine ends. This segmentation allows the cable to be independently accessed and replaced without disassembling the entire throttle mechanism, significantly easing maintenance while preserving the sensitive rotary control mechanism.
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 twist grip throttle assembly provides enhanced motor control sensitivity, reduces operator fatigue, and allows for easier maintenance by enabling a more natural arm position and simplified cable replacement.
Implementation Method 1
A grip having vibration dampening ridges is preferably received on the gripping area of the throttle activator
Data Source
AI summary
A twist grip throttle assembly and weed trimmer utilizing the same are described herein. The weed trimmer has a power head on an upper end of a drive shaft assembly. The power head has a power provider, such as a gas powered motor. A base assembly with a cutter head for receiving wrapped cord is on a lower end of the drive shaft assembly. A throttle activator includes a tubular member rotationally mounted on the drive shaft assembly. The tubular member defines a gripping area. Twisting rotation of the throttle activator adjusts an amount of power produced by said power provider.