Researches and solutions for optimising technical problem with TRIZ theory.

Ispas, Constantin ; Mohora, Cristina ; Tilina, Dana 等

1. INTRODUCTION

The concurential character in the car manufacturing field of application, concentrated on the globalisation and internationalisation, requires the application of some efficient methods and instruments in design and achievement of the new products. So, the introduction of some inventive and new methods requires a more complete satisfaction of the customers, regarding the technical performances, economical conditions, the price and the market launch at the right time and place.

The degree of innovation and the quality of the solutions depend almost 90% of what Pahl & Beitz (Pahl & Beitz; 1996) called "The development of solving principles" which belonged to the design process. That's why this stage is also named "the key stage" in the development of a product.

Taking into account the importance of this one, along the time, the researchers had developed more than 100 methods, instruments and techniques of creativity.

The research objective is to find a technical solution for the development of a new type of damper by applying some instruments of integrated methodology for solving problems called TRIZ.

2. GENERALS INFORMATIONS

The primary purpose of the shock absorber is to control spring and suspension movement. For the absorbers presented in the paper, this is accomplished by turning the kinetic energy of suspension movement into thermal energy, or heat energy, dissipated through the hydraulic fluid.

Shock absorbers are basically oil pumps. A piston is attached to the end of the piston rod and works against hydraulic fluid in the pressure tube. As the suspension moves up and down, the hydraulic fluid is forced through tiny holes, called orifices, inside the piston. However, these orifices let only a small amount of fluid through the piston. This slows down the piston, which slows down also the suspension movement (Figure 1).

The resistance of the shock absorber depends on the speed suspension and the number and size of the orifices in the piston. All modern shock absorbers are velocity sensitive hydraulic damping devices--meaning the faster the suspension moves, the more resistance the shock absorber provides.

[FIGURE 1 OMITTED]

Because of this feature, shock absorbers are made for the various road conditions.

As a result, shock absorbers reduce the rate of:

* Bounce,

* Roll or sway,

* Brake dive and Acceleration squat.

Shock absorbers work on the principle of fluid displacement on both, the compression and extension cycle. A typical car or light truck will have more resistance during its extension cycle then its compression cycle. The compression cycle controls the motion of a vehicle's unsprung weight, while extension controls the heavier sprung weight.

3. THE IDENTIFICATION AND THE SOLUTION OF THE PROBLEM

3.1 The problem

The damper influent directly the breaking efficiency, the direction and also the cars behaviour along the road.

Because the dampers wear is gradual and influence the wear of another's car components, the experts consider that these must be verified at each 20 000km.

Taking into account that a damper makes about 500 movements/km and after 20.000km about 10 millions movements, it is easy to imagine these wear degree.

A study achieved in the auto-services in Romania showed that because the roads bad quality, the wear on different components is very high at a smaller number of kilometres than the guaranteed one (about 80 000km).

Taking into account all these elements it was studied the possibility of the dampers improvement with the help of TRIZ (Ispas et al.; 2005).

3.2 The solution

In the first stage the problem that must be solved was clear defined. Generally speaking, some problems are not always clearly defined, and all necessary information are not enough obvious as know. That's why the problem will be very difficult to solve (Domb; 1997).

In order to clarify the problem, first, it was used the instrument called "Innovative Situation Questionnaire". As a result of ISQ application it was established that irrespective of the damper type the following conditions must be accomplished:

* To assure a corresponding absorbing of the coachwork and of the car wheels;

* To have a large (big) period of function;

* The weight and dimensions must be as small as possible;

* A simple construction;

* An easy assembling in the car suspension;

* To assure a correspond absorbing in different conditions of use.

The conclusion after using ISQ was that the best way to solve the problem is to modify some damper components.

Trying to solve the identification problem, some methods of TRIZ theory were utilized.

The first instrument chose was "Little smart people", a creative method very simple to apply: we have to imagine that a conflict zone from the interior of a system (a car, a device, a mechanism) represents, in fact, a lot of people in miniature. Utilizing this method appears that:

* Many small peoples are microscopic.

* Each one can be different as age, colour, sex, etc.

* This people are able to fulfil the received orders (moving, actions, etc.).

Then, a more complex approach of the problem was made by applying the following TRIZ instruments: The Contradiction Matrix, The Separation Principles and the method that associate the Su-Field Modelling and the 76 Standard Solutions (Cordova; 2002).

TRIZ considers that generally a problem supposes a conflict between two parameters. For example, x and y are two parameters that are in conflict and require a compromise. As x is improved, y is affected in a wrong way.

The instrument known as the Contradiction Matrix reunites 39 parameters and 40 inventive principles. The parameters are disposed horizontally (parameters that must be improved) as well as vertically (parameters that are affected). In the intersection points of these are mentioned the 40 principles of witch application should solve the conflict between these parameters. In this case, the parameters are:

* 27. Reliability

* 34. Reparability.

* 35. Adaptability.

* 36. Complexity.

The physical contradictions are the system requires which are reciprocally excluded. This situation is caused by a function, process or component (an object which must be heavy and light in the same time). The principles of separation are used to eliminate these contradictions. TRIZ introduced this instrument with the aim of facilitating the solving of technical problems, when there is a physical contradiction. The most important principles of dividing are:

* In time.

* In space.

* Of an object in its components.

* According to the conditions.

The last used method is Su-Field Modelling and the Solving Standards. TRIZ mentioned the fact that generally, the transition of an initial system A to an improved system B can be described as a transformation of a Su-Field structure.

When we built a Su-Field Model we must respect the following steps:

* The identification of the elements (S1, S2 and F) and the links between them.

* The construction of the initial Su-Field Model.

* The identification of the solution taking into account the 76 Standards.

* The development of the concept based on the found solution.

[FIGURE 2 OMITTED]

The solving standards are structured in five classes as follows:

1. The composition and the decomposition of a Su-Field Model.

2. The evolution of a Su-Field Model.

3. The transition to the super-system and micro-level.

4. Measuring and detecting standards.

5. Auxiliary Standards.

After we applied all of these TRIZ methods the result was a new type of damper which can be adapted for a larger variety of cars (Figure 2) (Tilina; 2008).

4. CONCLUSION

The cars manufacturing need a continuous products improvement and therefore a rise of the creative potential of the people that are in charge with the conception in order to be competitive on the market. The "traditional" instruments that support the creativity encourage the analysis and implicit the solving of the problems from all the points of view and possibly lead to a wide spectre of solutions. Moreover, these methods are based on human competence. Because of that, the creativity has remained an aleatory process, fact that doesn't enable an immediate found of solutions.

Even the producers guaranteed the function at normal parameters of the dampers for about 80 000 km, the research in the auto-services showed that because the roads bad quality, their life cycle of is smaller, irrespective of the damper type or the producer.

Taking in account all that, we applied TRIZ method and we had simplified the construction and improved the dynamic dampers characteristics. The result was a new ecological type of damper with really new characteristics like: a high outturn (200% compared with the classic one), easy to manipulate; low weight and the possibility to be set in different positions.

5. REFERENCES

Cordova, L. (2002). Contribution to a methodological approach of the innovation process: Application of TRIZ theory to the systems product--method--process, Doctor's degree thesis, University Luis Pasteur, Strasbourg

Domb E. (1997). How to Help TRIZ Beginners Succed, Invention Machine User Group Conference, New Orleans, LA USA.

Ispas C., Mohora C., Cioroianu D., Tilina D.(2005). Considerations regarding the simulation of creativity in forming specialists, 3rd Balkan region conference on engineering education, Sibiu, Romania

Pahl, G., Beitz, P. (1996). Engineering Design. A Systematic Approach", Springer, Berlin

Tilina, D. (2008), Contributions concerning with application of methodical integration in products conception, Doctor's degree thesis, UPB.