Crankshaft design system of the hottest four cylin

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Four cylinder in-line gasoline engine crankshaft design system

this paper uses vc++6.0 programming software as a tool, pro/toolkit, a secondary development interface application program of pro/engineer, as a means, and uses dynamic link library DLL to realize the communication between error T and MFC caused by the experimental force sensor of pro/engineer and pro/toolkit hydraulic universal experimental machine. Moreover, the full parametric design of crankshaft parts is connected with the open database ODBC, which realizes the systematization of data retrieval and data management. Taking CA488 as an example, the design system is described in detail

in recent years, the application of CAD software developed abroad in the automotive design industry has brought automotive design and development into a new, fast and intelligent era. With the rapid development of the domestic automobile industry, there is also an urgent need for a CAD system that is suitable for China's national conditions. However, China started late in this industry, and its ability to independently develop software is poor. Therefore, on the basis of foreign mature software, the secondary development of parts, systems and even whole vehicles has become a practical guiding direction

I. software development background and methods

1 Development background

among the many components of the automobile engine, the crankshaft is one of the most important, heaviest loaded and most expensive parts in the engine, which is called the backbone of the engine. Correct and reasonable crankshaft design has an important impact on the operating performance of the engine. However, since the production of crankshaft is mainly matched with the main engine, the degree of serialization, generalization and standardization of domestic crankshaft is very low. Even for the same type of crankshaft, the technical standards of part drawings are different and not common to each other. The confusion of domestic crankshaft product design has brought great difficulties to users' use and selection. It can be seen that according to the working conditions and development trend of the engine, designing a series of general-purpose crankshafts for the design and matching of various engines is the future road of engine crankshaft design

2. Development method

the crankshaft design system based on the secondary development of pro/engineer is based on the advanced development kit pro/toolkit provided by PTC company, using the integrated development environment of high-level programming language visual c++6.0, using dynamic link library DLL to realize the communication between pro/engineer, pro/toolkit and MFC, and connecting the crankshaft parametric design system with open database ODBC, It realizes the systematization of data retrieval and data management

II. Crankshaft design system

the crankshaft design system is started by clicking the "crankshaft design system (q)" menu on the right side of "help" on the pro/engineer interface (as shown in Figure 1)

Figure 1 menu bar menu of crankshaft design system

this menu bar menu includes five modules: crankshaft design calculation (n), crankshaft parametric design (c), fillet strength check calculation (y), engineering drawing output (g) and database (s). Among them, the crankshaft parametric design module also includes submenus "circular arc crank arm" and "linear crank arm". Through menu design, the structure of the whole system can be seen at a glance, and it is very convenient to use. The system starts with a simple and clear welcome interface (as shown in Figure 2), which first gives you a clear impression

Figure 2 welcome interface of crankshaft design system

1 Crankshaft design calculation module

each part of this crankshaft design system is a key development trend in China: the potential of emerging industries is large, which comes down from top to bottom, and the transmission of data is the key of this system. Therefore, the design and calculation module adopts a method similar to the attribute wizard, with three buttons "previous", "next" and "Cancel" to connect several modules, from front to back

crankshaft design is based on the design of internal combustion engine, so the overall design of internal combustion engine must be carried out first. Click the "start" button on the welcome interface to enter the overall design interface of internal combustion engine. This interface requires the user to input some known parameters that have a significant impact on the mechanical properties of plastics, such as cylinder diameter, rated power and rated speed, which lays a good environmental and design foundation for the later crankshaft design. Next is the "thermal calculation" interface (as shown in Figure 3), the "thermal calculation result" interface (as shown in Figure 4), the "dynamic calculation" interface (as shown in Figure 5) and the "dynamic calculation result" interface (as shown in Figure 6). Click "finish" to end the operation of this module

Figure 3 thermodynamic calculation parameter input interface

Figure 4 Thermodynamic calculation result interface

Figure 5 dynamic calculation parameter input interface

Figure 6 dynamic calculation result interface

2 Crankshaft parametric design module

click "crankshaft parametric design" on the menu to pop up the sub menus "arc crank arm" and "straight crank arm" for users to choose. The default unit of the interface is mm

click "circular crank arm", and the system enters the counterweight configuration interface as shown in Figure 7. The interface is divided into four combo boxes: parameter, part type, material, and property. Click the "display parameters" button set in the last line to display the corresponding value of CA488 crankshaft in each box. The "parameter" combo box is used by users to parameterize the design of the crank arm. Users can modify the values in the box according to their own wishes until they are satisfied. When the user changes the selected material, the quality value in the "properties" box below will change. The shape of the crank arm is complex and diverse, and it is irregular. If you want to calculate its volume, center of gravity and principal moment of inertia manually, it is quite difficult, and a lot of work needs to be done. With the help of the model characteristics of the crank arm, it can be realized very quickly

Figure 7 counterweight configuration interface

after modifying and selecting the parameters on the interface, click the "crankshaft parameterization" button. The crankshaft parameterization design adopts the form of modeless property page, and completes the three parts of "front end", "crank arm" and "rear end" respectively. Users can design their own graphic size according to the corresponding three-dimensional model displayed on the pro/engineer interface and the two-dimensional graphics of the corresponding part displayed on the interface. After modification, click the "update" button, and pro/engineer can regenerate the three-dimensional model according to the newly entered value. Figure 8 shows the parametric design interface of circular arc crank arm

figure 8 parameterized design interface of crankshaft crank arm

similarly, selecting a straight-line crank arm or a model with eight counterweights is a similar interface, but the invoked three-dimensional template model is different. I won't repeat it here

3. Fillet fatigue strength check module

in this module, the most important thing is the determination of each coefficient. The fillet shape factor determination interface (as shown in Figure 9) is an MFC dialog box in the form of a modeless property page. It includes stress concentration sensitivity coefficient, shape coefficient, material sensitivity coefficient, fatigue limit coefficient, size influence coefficient and strengthening coefficient. In this way, the corresponding coefficient can be determined without manual query, which saves a lot of manpower and time for users and greatly improves the design efficiency

Figure 9 size influence coefficient determination interface

click "OK" to enter the "fillet strength check" interface as shown in Figure 10. In this step of calculation, we need to use the crankshaft structural parameters determined in the previous parametric design. Here, we can directly call the data entered by the user in front, without repeated input by the user. When entering the interface, we can see the results

Figure 10 fillet strength check interface

click the "OK" button, and the system enters the last interface of the check module, "fillet fatigue strength check results". The system can calculate the final check safety factor through the first two safety factors displayed on the interface. Then click "finish". If the whole design process meets the requirements, a message box "Congratulations, successful design!" will pop up, If the result of the design is unreasonable, the message "unreasonable design, please try again" will pop up Prompt information of. Until this step, the design, calculation and verification required by the user are all completed. Next is the follow-up improvement work

4. Engineering equipment will not change due to resistance figure output module

click the fourth item "engineering drawing output (g)" in the menu bar. After a short reaction process, pro/engineer will automatically enter the engineering drawing mode. At this time, a two-dimensional figure as shown in Figure 11 and a modeless "engineering drawing size adjustment" dialog box will appear in the interface

Figure 11 the engineering drawing output interface

pro/engineer engineering drawing interface shows exactly the three views of the three-dimensional crankshaft model parameterized by the user in front: the main view, the top view and the side view, that is, the contents of the engineering drawing given by the general design requirements. By clicking the "adjust" button in the dialog box, the user can zoom in or out of the view. In addition, designers can activate the drawing behind with the mouse and make any view adjustment, such as single zoom in, zoom out, etc., which is very convenient, just as it is used in pro/engineer

another important problem is the size standard in engineering drawings. Click the "display dimension" button in the dialog box, and you can see the rapid process of dimensioning the view by the system. The interface after the standard is shown in Figure 12. Although the annotation looks a little messy, it does achieve the correct automatic annotation according to the user's input in the three-dimensional parametric design. As for how to better solve the problems of clear annotation and how to correctly and automatically generate title blocks, it will be an aspect of future research and development

Figure 12 dimensioned engineering drawing

5 Database link module

finally, for the continuity and perfection of the system, we designed the database link module. Click the last item "database (s)" in the menu bar, and the system enters the database link interface as shown in Figure 13. The parameters in the whole interface are composed of the main environmental parameters that need to be explained in the design of internal combustion engine and the basic structural parameters of crankshaft

Figure 13 crankshaft design system database interface

when the user completes this step, the whole process of the crankshaft design system is ended. In other words, users used to spend a lot of time and energy to complete the work. Now we can easily complete it by clicking the button and inputting a small amount of data. This is also the greatest significance of this system development

III. conclusion

the crankshaft design system based on the secondary development of pro/engineer has achieved the following three breakthroughs:

1 The realization of digitalization of chart query

2. According to the known three-dimensional model, directly call its volume, center of gravity position and principal moment of inertia

3. The development means of outputting engineering drawings and automatic dimensioning according to the model

this crankshaft design system has friendly interface, sufficient prompts, convenient and fast operation, which significantly shortens the product design cycle and improves the design efficiency. The system provides a complete information source for the follow-up process, has a certain product information data processing function, and lays a foundation for the serialization, standardization and generalization of crankshaft design

originally published in the magazine cad/cam and manufacturing informatization (end)

Copyright © 2011 JIN SHI