On the following pages we are going to describe the development of an “e-bike” motor. There are some requirements for the motor, which have to be considered. Today there are already different types of e-bikes. Almost all of them have fixed batteries and drive units. That means it is not possible to change the motor onto another bike, at least it would be very difficult. Our task now is to develop a motor, which is easily to change onto other bikes.
To accomplish such a development it is necessary to make a proceeding plan. We took the structure from the book (..) as a guideline.
• The first step is the Product Plan. It consists some pre planning, the mission statement to define the requirements and the project plan which is the schedule for the development.
• For the next we tried to Identify Customer Needs. To gather some data about customers we made a questionnaire. This data we tried to interpret in a customer needs table we also made a hierarchy of the most important requirements. After that we selected the customers, which could come in question.
• In third step we established Target Specifications. One of it was the product specification with metrics and the target values.
• The next step was the Generation of the Product Concept. Here we made different concept to for gaining ideas e.g. brainstorming, 6-3-5 – method. After that we researched on the Internet and made benchmarking to get more and better information about the different parts of the product.
• The last step was the Selection of the Product Concept. We developed 3 different concepts and decided by the pros and cons about the final one we should choose.
On the basis of these five points our report is structured.
Table of Contents
Introduction
Questionnaire
Hierarchical organization of the customer needs
Relative Importance
Product / Target Specification
Conceptual Design Ideas
Hub wheel Concept
Top Wheel Concept
The side-wheel concept
Project Goals and Themes
The primary objective of this work is to develop a modular and adaptable electric motor for bicycles that overcomes the limitations of current fixed-battery systems, thereby facilitating easier installation and transferability across different bikes. To achieve this, the authors utilize a structured development approach inspired by established design methodologies to define customer needs, establish technical specifications, and evaluate various conceptual designs.
- Systematic identification and hierarchical organization of customer needs.
- Development of technical product and target specifications.
- Benchmarking and comparative analysis of different e-bike propulsion concepts.
- Concept selection based on complexity, weight distribution, mounting simplicity, efficiency, and price.
- Calculations for motor power requirements and component selection.
Excerpt from the Book
Pro and Cons of the Hub Motor
Due to the fact, that the hub motor is directly connected with the back wheel, no losses of energy through friction will occur. One part of the motor is fixed at the bike-frame the other at the wheel. Compared with other measures of propulsion this has the advantage, that nothing could disturb the transmission of power. Therefore providing the whole system with a high degree of efficiency. If the wheel is powered by another small wheel of the motor (like the other two concepts) problems can occur regarding to the weather.
If its raining the friction will be less than in a dry condition. Frost can do no harm to the hub-motor, since there is no water between the critical parts which could freeze.
Mud and small stones can lead to a damage of the wheels of the other principles, the hub-motor can’t be affected by this.
The construction itself is consisting only out of few parts. There is no need for complicated mechanisms to fix a motor to the frame and transmit the power to the bike. It is simply one (a bit more sophisticated than the standard) motor inside of the wheel, a battery, a controller and some electrical connections leading to just three modules which have to be produced, stored and installed. Through the high degree of compatibility of motor, battery and controller a few differentiations of the modules lead to a large customisable variety of end products and only a small amount of spare parts.
A certain drawback of this principle is the fusion of the motor with the wheel. You can’t attach the motor to a standard bike, since the motor is integrated in the wheel. Therefore the bike needs a special wheel, with different kind of spokes and hub. This limits the usability of this propulsion principle to some provided standard wheels, whereas the other mechanisms can be attached to a wide range of bikes. Due to the fact that you have to buy the whole back wheel the upgrading cost of you bike will be much higher compared to the plain costs of the propulsion system. Therefore the user may hesitate to upgrade his bike. Maybe he postpones the purchase till he needs a complete new bike or he will use a different means of propulsion.
Summary of Chapters
Introduction: This chapter outlines the development task of creating an adaptable e-bike motor and establishes the five-step procedural plan used as a guideline for the report.
Questionnaire: The authors describe the methodology used to gather international customer needs from the primary target group (elderly people) via interviews.
Hierarchical organization of the customer needs: This chapter details the clustering and generalization process of raw customer data into thirteen specific categories of needs.
Relative Importance: The team assigns degrees of importance to the identified need clusters based on customer feedback and internal team consensus.
Product / Target Specification: This section translates customer needs into measurable technical metrics, benchmarked against competitors to provide concrete engineering targets.
Conceptual Design Ideas: This chapter presents and evaluates various propulsion concepts, including the Hub wheel, Top Wheel, and side-wheel approaches.
Hub wheel Concept: This chapter analyzes the design of integrating a motor into the rear wheel hub, highlighting its efficiency and construction simplicity alongside its limitations regarding bike compatibility.
Top Wheel Concept: The authors examine the friction-based top-wheel propulsion principle, discussing its ease of retrofitting versus its susceptibility to weather and wear.
The side-wheel concept: This section introduces alternative side-actuated propulsion mechanisms, discussing their mechanical configurations and potential drawbacks like complex part counts and tyre wear.
Keywords
Product Development, E-bike, Motor, Customer Needs, Technical Specifications, Design Methodology, Propulsion, Hub Motor, Concept Scoring, Benchmarking, Sustainability, Rechargeable Battery, Efficiency, Engineering, Innovation.
Frequently Asked Questions
What is the core purpose of this study?
The report focuses on developing an electric motor for bicycles that is easily interchangeable between different bikes, addressing the lack of modularity in current market offerings.
What are the central thematic areas?
The study covers the entire product development process: understanding customer needs, defining technical product specifications, evaluating design concepts, and selecting the most viable technical solution.
What is the primary design goal or research question?
The primary goal is to create a motor system that is adaptable to a wide range of existing bicycles, thereby lowering the barrier for users to upgrade their standard bikes.
Which scientific methodology is applied?
The authors use a structured product development methodology based on Ulrich and Eppinger (2000), utilizing tools like customer interviews, requirement hierarchies, target specifications, and concept scoring.
What is covered in the main body?
The main body details the data collection from potential users, the translation of their qualitative needs into quantitative technical metrics, and the critical assessment of various propulsion concepts.
Which keywords characterize this work?
Key terms include product development, e-bike motor, customer needs, technical specifications, design concept evaluation, and propulsion systems.
How is the "Hub wheel" concept compared to the "Top wheel" concept?
The Hub wheel is favored for its high efficiency and simplicity due to direct power transmission, whereas the Top wheel is noted for its ease of retrofitting but penalized for friction-based power losses and weather dependence.
Why was the "asymmetrically mounted motor" identified as the most promising concept?
Following a concept scoring process, the asymmetrical mount was selected as it balances technical performance, affordability, and ease of mounting better than the other analyzed concepts.
- Quote paper
- Tom Kuehner (Author), Jan Hebborn (Author), Christopher Fritz (Author), Fest (Author), Romain Mousson (Author), Planes (Author), 2002, Development of the ebike, Munich, GRIN Verlag, https://www.grin.com/document/18077
