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Elementary structure of the rotation frequency regulator

In the general casethe rotor rotation frequency controller can consists of the following elements ordevices:

· sensor - a device that measures the value of controlled parameter (in this case the frequency of rotation);

· adjuster – a device which allows to change the regulator’s settings, designating different parameters of rotor rotation frequency (for example engine control lever or electric toggle-engine operation mode adjuster)

· control device - a device that allows you to change the value of the control factors(for example fuel);

· comparison element - a device that ensures detection of two values difference ​​, one of which is given by spring of setting the device, and the other is determined by position of sensing element;

· servomechanism - a device that allows to increase the efforts, that are developing by sensing element, and is used for replacement ofthe control device;

· control unit- controls the external energy supplying to the servomechanism, driven by theefforts of the sensing element at the moment of deviation from the desired speed value;

· executive feedback - feedback that exists between the sensing element and the control device (provides the necessary replacement of thecontrol device);

· stabilizing device – is used to improve the dynamic properties of ACS (provides stability ofACS). Realized as a feedback mechanism. According to the character of this mechanism can be distinguished frequency rotation regulators with rigid (proportional) feedback and with flexible (elastic) feedback.

 

Elementary structure of the frequency rotation regulatordepends on the requirements that it must meet and the device where it will be used. Example of the elemental structure of widely used frequency rotation regulator with spool-type control device is shown in Figure 5.1.

 

ECL
Fig. 5 Frequency rotation element

 

1 –centrifugal weight (sensitive element); 2 – needle for transmitting the frequency of rotation; 3 - slide valve (has the function of comparison elementand control device); 4 - set up device spring; 5- cam; ECL - engine control lever (set up device); SM – servomechanism; CD – control device; ðì - oil pressure; Gï – fuel consumption; Gïä – metered fuel consumption

The principle of regulator operation is as the next.

 

 

In the stable rotation frequency at fixed position CAR efforts from the sensitive elements 1 andset up device spring4 are in the position of balance.

At deviation of engine from the balanced position, for example, due to external conditions (ð*í, Ò*í) changes towards rotational frequency increasing or decreasing, the efforts from thecentrifugal forces applied to the levers, also changes.

Changes in the efforts of centrifugal weightwill be accompanied by changing ofweights position of and correspondently of the control slide valve3 position.

As a result of replacement of slide valve3 oil under pressure access ðì = constinto the working servomotor SM cavityopens.



At the same time from the opposite cavity SM oil will be squeezed out by the piston to the outlet. As a result,SM will effect on the position of control device CD, at replacement of which fuel feeding into the combustion chamber changes. Providing that CD will change the fuel feedingso, that the frequency of rotation will be at the original value again.

Transferring theengine from one mode to another mode of operation is achieved by shifting of ECL to a new operation mode.

In addition it should be noted that on the position of the slide valve3 except ×Åand set up device spring 4 can also affect the external perturbation as a form of vibration, thermal expansion of housing regulator, friction and other factors.

These circumstances must be considered atfrequency rotation regulator designing and external disturbances must be reduced to a minimum.

Below will be considered frequency rotation regulators GTE (GTU), made on the principle of deviation from the desired speed value control.

 

In ACS of modern GTE (GTU), working on liquid or gaseous fuel, used four types of frequency rotationregulators, characterized by operationalprinciple: direct action regulators,indirect action regulators of simplest scheme (without feedback), indirect actionregulators with hard feedback, indirect actionregulators with isodromic feedback (IF).

 

 


Date: 2015-02-16; view: 918


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