Consider the hierarchy of the functional scheme of automatic control of fuel level in the carb. Define functional elements of the control system, find analogies in the problem to be solved.
Define the principle of operation of the device. In our example, the increase in consumption of the fuel level in the float chamber decreases, resulting the lowering of the float. Along with the float drops the needle valve is opened by increasing the fuel mixture. Result: the fuel level in the float chamber is restored to normal.
Install, what is the object of regulation (RR), the regulated value, disturbing and control actions in the system under consideration. In this case the object is a float chamber, in the space which the regulatory process. The value that you want to change the fuel level. Perturbing effect is the change in fuel consumption. Control the flow of fuel into the chamber to restore the desired level.
Locate a function block, which is the Executive unit (EU). In this example, this shut-off valve. Below is what the needle is, the more mixture will be filed in the float chamber.
Determine that system plays the role of the sensor (D) and setting device (memory). We have sensor is the float used to measure the fuel level and converts this level to move the needle valve. Driver unit would be the length of the needle stem.
Bring all blocks into a single functional circuit. Sign each box and specify relationship between them. As a result, you should get an image that clearly reflects the functional chain in the system of automatic control. By analogy with the example make a similar pattern for you review system.
Advice 2: How to distinguish a block diagram of a functional
A schematic is a drawing or picture that describes the main idea of any device or structure. Can be performed without scale and legend. In the design documentation describes the components of the product, the connections between them.
The block diagram gives a General idea of the principle of the device. It depicts the set of links of the object, the relationship between them. Each link is part of the object and is responsible for some basic function.
Principles of building structural scheme
The links in the diagram represent in the form of rectangles or of graphic symbols that are connected by interconnection lines. These lines should set the arrows to indicate the direction of course of the process between the links. Each link of the products in the diagram must have a name or designation.
The name may be in the form of the symbol and describe the item type. In the structural scheme allowed the use of additional charts, diagrams and tables, and you can also specify parameters and characteristics. Structural scheme should give an idea about the interaction of units of the product.
Principles of functional diagrams
Functional diagram makes it clear what is happening in individual nodes of the device, explains how it works. Functional parts of devices and connections between them indicate the kind of special graphic symbols. Separate functional parts are allowed to portray in the form of rectangles. If a device or link is depicted as a rectangle, then you should specify the type and the document on the basis of which the device is used.
Each element of the functional circuit must be assigned to the symbol. It is recommended to specify the technical characteristics of each functional part of the device. For each group of functional elements must be specified designation, based on the diagram, or its name.
Diagram allowed the display of additional graphs, charts, tables, determine the sequence held in the device, and a specification of the characteristics of the individual elements and points (voltage, current, pulses, etc.).
The difference of the block diagram from the functional
Thus, the distinction of structural and functional schemes is that the structural scheme outlines a General picture of the device and indicates the location of functional elements and units, and the functional more accurately describes the position of the elements in the nodes, the interaction between schema elements.