Diaphragm pumps.
Pumps are diaphragms, pistons, made of flexible material (rubber, leather, lacquered fabric, etc.).
The membrane separates the working chamber from the space into which the liquid should not penetrate.
In the diaphragm pump presented, a valve box with suction and discharge valves is located separately, and the diaphragm deflection is carried out due to the reciprocating motion of the plugin the pump cylinder / filled with a special liquid. Diaphragm pumps of this type are often used for pumping liquids contaminated with various impurities (sand, sludge, abrasive materials), as well as chemically active liquids and mortars.
The diaphragm can be driven not only by a plug but also by a conventional lever mechanism. Figure 6, b shows a diagram of a lever-operated diaphragm pump. Working chamber 5 has two connections: suction 3 and pressure 1, which are connected to the chamber through the suction 4 and pressure 2 valves. Diaphragm 6 is connected to stem 7, which makes reciprocating movements. Diaphragm pumps of this design are used as gasoline pumps on car engines. These pumps have two levers: one for manual gasoline pumping and one for continuous gasoline pumping while the engine is running. The latter is driven by a special cam of the distribution engine.
Classification of rotary pumps and their features.
Rotary pumps, as well as piston pumps, are positive displacement pumps. According to the nature of the movement of working elements (displaces), rotary pumps are subdivided into rotary and rotational-rotational: rotational pumps include gear (gear, rotary) and screw pumps; rotational-rotational pumps - plate (slide) and piston (radial and axial).
Rotary pumps usually consist of three main parts:
The pump consists of a stater (fixed housing), a rotor rigidly connected to the shaft and avoiding unit (one or more). In some designs, the rotor is also avoiding the unit at the same time.
The working process of rotary pumps has the following features. When the rotor rotates, the working chambers move, change their volume and, cutting off the liquid from the suction cavity, move it to the discharge cavity. With this principle of operation, there is no need for suction and discharge valves, and the working process is divided into three stages: filling the working chambers with liquid; closing the working chambers and their transfer; displacement of liquid from the working chambers.
The specifics of the working process of rotary pumps determine their special properties:
- 1) high speed: speed of rotation reaches 5-103 minutes;
- 2) uniformity of supply, the possibility of its regulation and reversal;
- 3) reversibility, i.e. ability to work as a hydraulic motor;
- 4) ability to create high pressures at sufficiently high efficiency;
- 5) small mass and volume per power unit;
- 6) high reliability in operation;
- 7) ability to work only on clean, non-aggressive liquids (not containing abrasive and other particles), having lubricating properties, which is due to small gaps of rotating rubbing parts, processed with high accuracy.
If the first six properties are the advantage of rotary pumps, the latter is their disadvantage, as it limits the scope of application of the pumps.
The feed rate of rotary pumps is determined by the size of the working space and rotor speed, as well as the strength of the pump elements. If the gate valve on the pressure line is accidentally closed, the pressure may increase above the permissible level, which will cause the pump to break or damage. For this reason, overload protection equipment is required and the strength of the pump elements must be sufficient (taking into account the resistance of the pressure line).
Rotary pumps are most widely used in technology, especially where a relatively low flow rate requires high pressure. They are successfully used in hydro transmissions, in automatic control systems, in gas turbine and rocket fuel systems, in hydraulic presses, in engine lubrication systems for pumping viscous liquids, in oil, coke ovens and other industries.
Since rotary pumps have the property of reversibility, i.e. they can work as hydraulic motors (hydraulic motors) when brought to them by liquid under pressure, they are sometimes called hydraulic machines in the technical literature; in the future, we will use this term.
Gear pumps.
Of all the rotary pumps, gear pumps have the simplest design. They are made with external or internal gears. Pumps with external gears are most common. The pump consists of a pair of identical gears
