TRIZ bicycle brake skin conceptual design
chung Ping Chiang and Ching Huang tseng
department of mechanical engineering, National Chiao Tung University
hsinchu 30056, Taiwan,
Tel: ext. 55155 fax:
* graduate student
* * Professor
if you only use the existing resources of the group
there are many kinds of brakes used to stop or slow down the speed of bicycles. Due to economic or convenient factors, caliper or lever brakes are the most common. When the operator presses the handle, the brake will jam the rim of the bicycle. Such a brake device usually consists of two brake shoes installed in the brake frame, which are relatively installed on both sides of the rim. The brake shoe contacts the rim and brakes by friction. (see Figure 1)
Figure 1 bicycle brake structure
it is obvious that when it is wet or the surface is polished, the contact surface will have a smaller friction coefficient and thus have a smaller braking force. Caliper or lever brake has no protective device, which is easy to be damaged by the weather. In addition, water film or gravel will reduce the friction coefficient. In fact, bicycles are either designed for dry or wet ground. Therefore, it is necessary to design a brake suitable for any weather to ensure safe driving
in the past, engineers tried various experiments to find materials that could improve braking performance, such as reliability and stability, in all climatic conditions. Aluminum alloy rims equipped with a specific brake material can reduce the friction coefficient when dry, but increase when wet . This is the most common method in recent years. Unfortunately, if there is sand, these soft aluminum will be easily worn off. Pieces of aluminum embedded in the brake will be oxidized to Al2O3, and then the rim will be worn away faster, and the dry friction coefficient will be reduced to a very dangerous level. For steel rims, there is no such problem. However, generally used to improve the methods that are applicable in all kinds of climates will bring inconvenience. In other words, conventional compromise cannot overcome technical contradictions. In this way, TRIZ is needed to solve the system contradiction
calculation of system conflict
in order to get the correct formula, it is necessary to re analyze the system conflict and design requirements. The requirements of the system discussed are simply defined as follows:
the brake shoe is applicable to any climatic conditions, and excessive wear of the rim is avoided. Moreover, the system itself cannot be greatly changed
the development of bicycle brakes suitable for any climatic conditions can be evaluated from two perspectives. The first point is that the brake is made of materials suitable for one climatic condition, dry or wet, and the user should change the brake in different weather. Second, when the rim is covered with water film or gravel, it will have different properties under dry or wet conditions. Therefore, it is not easy to solve this problem before the core problem is found. However, the usual methods to solve contradictory problems can be simply stated as follows:
1. By changing or adjusting the brake, the reliability can be improved under dry or wet conditions. But it is inconvenient to use
2. Improve the stability under any conditions by adjusting technical parameters, such as brakes and rims
by using the contradiction matrix of Li Donger, director of the equipment industry department of the Ministry of industry and information technology, and 40 invention principles, it is not necessary for people to compromise among system contradictions. Problems containing contradictions can be stated again in the form of contradiction matrix as follows:
A. performance "reliability" leads to the reduction of performance "convenience"
b. performance "stability" leads to performance "harmful side effects"
from the contradiction matrix "reliability/convenience", we can see three invention principles. As follows:
1. Cheap short-term objects replace expensive long-term ones (No. 27)
2. Turn to another dimension (No. 17)
3. Composite materials (No. 40)
repeat the above steps to get the technical contradiction about "stability/harmful side effects". The proposed principles of invention are as follows: the carbon fiber reinforced composite molding and processing technology was exhibited at the recent ipf2014 (2014 Japan International Plastics Machinery Exhibition):
1. changing the physical and chemical properties of objects (No. 35)
2. Media (No. 24)
3. Flexible or film (No. 30)
4. Mechanical vibration (No. 18)
considering the system requirements, It is feasible to try to use "composite materials" and "media" at the same time
"composite material" principle is:
"replace uniform material with composite material"
"medium" principle is:
"use intermediate objects to transfer or perform functions"
"connect objects with another object that is easy to remove in a short time"
a separate brake structure is the application of the above "composite material" principle. It is a convenient way to overcome the contradiction of "reliability/convenience". Richard C. Everett in the United States applied for this patent and was approved in 1999. The device is composed of two different elastic rubbers, which are suitable for dry and wet conditions respectively. Figure 2 shows the section diagram
Figure 2 patent profile
combining "composite material" and "medium" can get an ideal design, which can be patented. As shown in Figure 3, a movable soft rubber is installed at the front end of the brake, and the tilt is adjusted with a spring. Move the rubber surface to preset some distance from the rim. When braking, move the rubber to contact the rim first and wipe away the water film, sand and dust. When the brake skin contacts the rim, it can have the same effect under any weather conditions. In this way, TRIZ has successfully solved this systematic contradiction
Figure 3 new brake concept (in U.S. patent application)
in this study, the system requirements of bicycle brake are discussed. The formula to solve the system contradiction is correctly established. The so-called research example of U.S. patents shown in Figure 3 fully proves that the result given by the contradiction matrix is a very outstanding innovation tool. Through the combination of the invention principles of different system contradictions given by Allie special rier contradiction matrix, a braking concept that can be applied under any climatic conditions is obtained
1 Frank Rowland Whitt and David Gordon Wilson, Bicycling Science, 2nd edition, The MIT Press, 1990.
2. Altshuller, Genrich, 40 Principles: TRIZ Keys to Technical Innovation, 1st edition, Technical Innovation Ceter, Inc., Jan. 1998.
3. John terninko, alla zusman and Boris zloti Jinan experimental machine factory has produced experimental machines for many years n, step by step triz: creating innovative solution concepts, 3rd Edition, responsible management Inc., 1996
4. Victor R. Fey and Eugene I. Rivin, The Science of Innovation, TRIZ Group, 1997.
5. United States Patent, Patent Number: U.S. 5,896,955. (end)