Piston air pump with valves presentation. The topic of the lesson is “Plumbing. Piston liquid pump. Hydraulic Press". returns to its original position, and

Class: 7

Presentation for the lesson

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The purpose of the lesson: Acquiring knowledge about specific technical devices created by people to satisfy their needs based on open laws.

Lesson objectives:

• Study the structure, purpose of the water supply system and the piston liquid pump.
• Consolidate knowledge on calculations numerical values physical quantities in specific situations.

Equipment: Computer, projector, interactive whiteboard or screen, CD disk “Library of visual aids in physics” grades 7-11. from “1C: Education 3.0” (Busturbat, Formosa) and presentation (with a set of slides prepared for the lesson).

Demos:

• Presentation.
• Computer animation “The operating principle of a pump” (CD-disk “Library of visual aids in physics” grades 7-11 from “1C: Education 3.0”).

During the classes

1. Organizing time(1 min).

2. Repetition of what has been learned. Frontal survey-conversation (10-15 minutes).

Teacher: Guess two riddles (the teacher reads the riddles, and slides from the presentation are shown on the screen):

1 slide (man on a rock)

We're going up the mountain,
It became difficult for us to breathe.
What kind of devices are there?
To measure pressure?
(hole barometer)

slide change

Slide 2 (barometer image)

There's a plate hanging on the wall,
An arrow moves across the plate.
This arrow is forward
Finds out the weather for us.
(hole barometer)

Teacher: What is a barometer?

Student: A barometer is a device for measuring atmospheric pressure.

slide change

3 slide (Pascal's water barometer)

Teacher: (teacher calls student to the board)

In Fig. Pascal's water barometer is shown. What is the height of the water column in this barometer at normal atmospheric pressure?

)

Teacher: Let’s check the solution to the problem (opens part 2 of the slide with a mouse click). Which barometers are most often used in practice and why?

Student: In practice, the aneroid barometer (from Greek word“aneros” - liquidless), because These barometers are portable, reliable and liquid-free.

Teacher: Tell us the internal structure of this device.

slide change

4 slide (internal structure of the aneroid barometer)

Student: (Showing on the slide) The main part of the barometer is a corrugated metal box from which air has been pumped out, and in order to Atmosphere pressure it is not crushed, the lid is pulled upward by a spring. A pointer is attached to the spring using a transmission mechanism, which moves along the scale when the pressure changes.

Teacher: What are pressure gauges used for and where are they used?

Student: Pressure gauges are used to measure the pressure of liquids or gases. (from the Greek word “manos” - rare, not dense). They are used in technology and medicine (measuring human pressure, air pressure in scuba gear, determining pressure in gas cylinders, etc.)

Teacher: What types of pressure gauges do you know?

Student: There are various designs of pressure gauges. The simplest: metal or tubular

slide change

Teacher: Explain the structure of a metal pressure gauge using the slide in front of you.

slide change

6 slide (metal/tubular pressure gauge device

Student: (Showing on the slide) The main part of a tubular pressure gauge is a hollow bent into an arc metal tube. One end of which is sealed and connected to the pointer using mechanical links, and the other is connected to the vessel in which the pressure is measured using a tap.

Teacher: What other pressure gauges are there? Tell us about the design of such a pressure gauge.

Student: There is also a liquid U-shaped pressure gauge

slide change

7 slide (liquid U-shaped pressure gauge device)

Student: (Showing on a slide) Liquid U-shaped pressure gauge. Its main part is a double-bend glass tube shaped like the Latin letter “U”, in which a liquid (for example, water or alcohol) is poured. The operation of such a pressure gauge is based on comparing the pressure in the closed knee with the external pressure in the open knee. The measured pressure is judged by the difference in fluid heights in the knees.

Teacher: Which vessels are called communicating? Give examples.

Student: Communicating vessels are vessels connected to each other. This is a samovar, a kettle, a siphon under the sink, a water meter glass, a water supply system, and artesian wells.

Teacher: Formulate the law of communicating vessels

Student: In communicating vessels, the surfaces of a homogeneous liquid are established at the same level

slide change

Slide 8 (Ship in the lock)

Teacher: Carefully look at the lock diagram and answer the question: “Does the ship rise or fall in the lock and why?” (start animation by clicking the arrow -> you can speed up viewing)

slide change

Slide 9 (lesson topic)

2. New material(20 minutes)

Board type:

Teacher: Write down the topic of the lesson from the board in your notebook:

"Water pipes. Piston liquid pump”

Teacher: The development of life is inextricably linked with the hydrosphere.

Slide 10 (spruce on the shore of a mountain lake)

Water was the basis through which life arose. Water is the main element of our food. A person cannot live without water.

People use water (the teacher shows slides and gives explanations): in irrigation

slide change

Slide 11 (irrigation of agricultural land)

on transport

slide change

12 slide (transport)

slide change

energy

13 slide (station)

for domestic purposes and preparation of drinking water

slide change

Slide 14 (water and pickles)

Teacher: Guys, what do you think, how is it that water from rivers, lakes, reservoirs and from underground is supplied to our apartments, factories, i.e. to consumers?

slide change

Slide 15 (village on the river bank)

Student: Water taken from a source is supplied to consumers through a water pipeline.

Teacher: That's right.

The first water supply structures - wells, irrigation canals and aqueducts appeared in places of development ancient civilizations during their heyday and were a condition for this heyday.

Let's listen historical information, which he prepared (the teacher says the student’s last name, first name).

slide change

Slide 16 (photo of a Roman aqueduct that has survived to this day)

Student: An aqueduct is a structure for transmitting water over long distances (from Latin aqua - water, duco - I lead). This is peculiar water channel, raised above the ground and covered at the top to protect against evaporation and water pollution. In places where the earth's surface is low, the aqueduct is supported by arches. The water moved along it by gravity along a slightly inclined chute. Aqueducts were already built in Assyria at the beginning of the 7th century BC.

Roman aqueducts are especially famous. The first of them was built in 312 BC. and had a length of 16.5 km. The longest aqueduct, 132 km, was built in the city of Carthage by Emperor Hadrian. Almost 100 cities of the Roman Empire were supplied with water using aqueducts.

Teacher: Historically, water supply refers to not only aqueducts or canals for supplying water, but also the entire system of structures intended for the extraction, transportation, processing and distribution of water. We can conclude:

A water pipeline is a system of engineering structures that serve to supply water to the population, plants and factories (write in notebook)

slide change

Slide 17(scheme of a modern water supply system)

Let's consider simple diagram modern water supply system, which requires the presence of a water tower. (explanation on slide)

Water is taken from the source (1) by pumps (2), which are driven by electric motors (3). Water under pressure through a pipe (4) enters a large water tank located in a water tower (5), which serves to create water pressure and also to store it. From this tower, at a depth of about 2 m, pipes are laid, from which branches go to each house and then the water flows into the water supply network (6). Due to natural hydraulic pressure, water can rise through the pipes to a height approximately equal to the height at which the water tank is located.

Such a water supply system, for example, is used for mechanized water supply to a farm. To water animals, prepare feed, and wash equipment on farms, you need a lot of water.

IN industrial scale Electric pumps are used to collect water.

We will consider with you the simplest design hand pump, with which you can supply water.

slide change

18 slide - (piston liquid pump)

In front of you is a piston liquid pump (the teacher explains the design of the pump and demonstrates its elements)

The pump consists of a cylinder and a piston tightly adjacent to the walls of the cylinder, which can move up and down.

The piston itself has a valve that opens only upwards. The same valve is located at the bottom of the housing . Let's consider the principle of operation of the pump.

The teacher launches the animation on the CD disk “Library of visual aids in physics” grades 7-11. from “1C: Education 3.0”

After watching the animation, we return to slide 18 and once again discuss the principle of operation of a piston liquid pump.

When the piston moves upward, water under the influence of atmospheric pressure enters the cylinder, lifts the lower valve and moves behind the piston

When the piston moves downwards, the water under the piston presses on the lower valve and it closes. At the same time, the water pressure in the space under the piston increases and the upper valve opens and the water flows into the space above the piston.

The next time the piston moves upward, the valve in the piston closes. The water above the piston rises with it, while the lower valve opens again and water fills under the influence of atmospheric pressure bottom part pump under the piston.

The amount of water above the piston increases with each subsequent lowering. When the piston is raised, the water rises with it and pours out through the drain pipe. This process is repeated cyclically.

Let's watch it a second time. (restart animation)

This pump is used to pump water from lifeboats of ships, at a pump in villages where water is taken from wells.

3. Consolidation and repetition (10 -15 minutes)

18 slide (piston liquid pump)

Teacher: Why does the bottom valve open when the piston rises and water moves behind the piston?

Student: Because of the pressure difference. The pressure under the piston is less than atmospheric pressure and water enters the cylinder under atmospheric pressure.

Teacher: Why does the bottom valve close when the piston moves down?

Student: When the piston moves downwards, the water under the piston presses on the lower valve and it closes. At the same time, the water pressure in the space under the piston increases and the upper valve opens and the water flows into the space above the piston.

Teacher: Let's move on to solving problems.

Teacher: (teacher calls the student to the board and reads out the task)

What is the height of the water tower (in meters) if water has to be lifted into it by creating a pressure of 500 kPa with a pump? The density of water is 1g/cm3. Consider the coefficient g to be 10 N/kg.

(the student solves the problem, making the necessary notes on the board and giving the necessary explanations )

The teacher checks the solution to the problem and gives a grade.

Teacher: (teacher calls the 2nd student to the board and reads out the statement of the problem)

What minimum pressure should a pump develop to supply water to a height of 55m? (Write your answer in atm.)

Student: (solves the problem, making the necessary notes on the board and giving the necessary explanations )

[If there is time left, then you can solve problems No. 583-585 (493-495) from the collection of physics problems for grades 7 - 9 educational institutions authors V.I. Lukashik, E.V. Ivanova]

4. Homework: paragraph 44, questions to the paragraph; task No. 97

Bibliography.

1. Physics textbook S. V. Gromov, N. A. Rodina 7th grade. M.: “Enlightenment”, 2010.
2. School encyclopedia. Volume “History of the Ancient World” M.: “Olma - Press Education”, 2003.
3. Elementary physics textbook. Volume I, edited by academician G.S. Landsberg, M.: “Science”, 1985. Main editorial office of physical and mathematical literature.
4. Collection of problems in physics for grades 7-9 of general education institutions V.I. Lukashik, E.V. Ivanova. M.: “Enlightenment”, 2009.

Municipal autonomous educational institution

"Lyceum No. 7" Berdsk

Pressure gauges Piston Liquid Pump Hydraulic Press

7th grade

Physics teacher I.V.Toropchina

Pressure gauges

To measure more or less

atmospheric pressure is used pressure gauges

(from Greek "manos" - loose, "metreo" - I measure).

There are pressure gauges liquid and metal .

Liquid pressure gauge

The liquid pressure gauge consists of a double-bend glass tube,

into which some liquid is poured. With flexible

tubes, one of the pressure gauge elbows is connected to a round flat

a box covered with rubber film.

Liquid pressure gauge

The operation of the pressure gauge is based on comparing the pressure in a closed

knee with external pressure in the open knee. The deeper

immerse the box in liquid, the larger it becomes

the difference in the heights of the liquid columns in the pressure gauge elbows, and thus

more pressure is produced by the liquid.

Metal pressure gauge

Using a metal pressure gauge

measure blood pressure compressed air and other gases.

1.A metal tube bent into an arc

2. Arrow

3.Zubchatka

4. Crane

5. Lever

Metal pressure gauge device

The end of the tube communicates with the help of tap 4 with the vessel in which the pressure is measured.

As the pressure increases, the tube

unbends. Closed movement

its end using lever 5 and

teeth 3 are transmitted to the arrow

2, moving near the instrument scale.

When the pressure decreases, the tube

(due to its elasticity)

returns to previous position, A

arrow - to zero division

scales.

Application of pressure gauges

Pressure gauges are used in all cases where

need to know, control and regulate

pressure. Most often, pressure gauges are used in

thermal power engineering, chemical, petrochemical

enterprises, food industry enterprises.

Pressure gauge for measurement blood pressure called: tonometer

Piston Liquid Pump

The action of piston liquid pumps is based

on the fact that under the influence of atmospheric pressure

the water in the tube rises behind the piston .

Piston liquid pump design

1 – piston 2 – 2 – valves

Pump operating principle

When the piston moves up water, under the influence of atmospheric pressure, enters the pipe, lifts the lower valve and moves behind the piston. When the piston moves down The water under the piston presses on the bottom valve and it closes.

Pump operating principle

At the same time, under water pressure, the valve inside opens

piston, and water passes into the space above the piston. At

subsequent upward movement of the piston, the

the water above it, which is poured into the barrel. Behind the piston

a new portion of water rises, which upon subsequent lowering of the piston

will be above him, etc.

How does an air chamber piston pump work?

1-piston

2-suction valve

3-discharge valve

4-air chamber

5-handle

• Mechanisms that operate using some kind of liquid are called hydraulic (Greek “hydro” - water, liquid).

• Main part hydraulic machine There are two cylinders of different diameters, equipped with pistons and connected by a tube.
• The space under the pistons and the tube are filled with liquid (usually mineral oil).
• The heights of the liquid columns in both cylinders are the same as long as no forces act on the pistons.

Hydraulic machine formula

• Let us denote the forces acting on the pistons - F 1 And F 2 , piston areas - S 1 And S 2 .

• Then the pressure under the small piston is: p 1 = F 1 S 1 , and under the big one: p 2 = F 2 S 2 .
• According to Pascal's law, pressure is transmitted equally in all directions by a fluid, therefore p 1 = p 2 Substituting the corresponding values, we get

F 1 S 1 = F 2 S 2

When a hydraulic machine operates, a gain in force is created equal to the ratio of the area of ​​the larger piston to the area of ​​the smaller one.

With the help of a hydraulic machine, a small force can balance a large force!

Hydraulic Press

A hydraulic machine used for pressing (squeezing) is called hydraulic press (from the Greek “hydravlikos” - water).

Hydraulic Press

Hydraulic presses are used where

required great strength. For example, for squeezing oil from

seeds for oil mills, for pressing plywood,

cardboard, hay. In metallurgical plants, hydraulic

presses are used in the manufacture of steel machine shafts,

railway wheels and many other products.

Modern hydraulic presses can

develop strength in tens and hundreds

million newtons.

Solve problems

Problem 1

What gain in strength does a hydraulic press provide?

Calculate it if F 1 = 500 N,

S 1 = 100 cm 2 , F 2 = 5 kN, S 2 = 1000 cm 2

Problem 2

Hydraulic press piston area 200 cm 2 and 0.5 cm 2 .

A force of 4 kN acts on the large piston. What force applied to the small piston will balance it?

Problem 3

The hydraulic press provides a 7-fold increase in strength. Its small piston has an area of ​​300 cm 2 . What is the area of ​​the large piston?

Answers

Problem 1

Problem 2

F 1 = 100 N

Problem 3 S 2 = 2100 cm 2

Homework

§ 47, 48, 49,

ex. 24 (3), p. 141,

exercise 25, page 144,

task 1, page 144

Types of hydraulic pumps Based on the nature of the force action, and therefore the type of working chamber, dynamic and volumetric pumps are distinguished. In a dynamic pump, the force on the liquid is carried out in a flow chamber, constantly communicating with the inlet and outlet of the pump. In a positive displacement pump, the force on the liquid occurs in the working chamber, which periodically changes its volume and alternately communicates with the inlet and outlet of the pump. Dynamic pumps include: 1) vane: a) centrifugal; b) axial; 2) electromagnetic; 3) friction pumps: a) vortex; b) screw; c) disk; d) jet, etc. Volumetric pumps include: 1) reciprocating: a) piston and plunger; b) diaphragm; 2) winged; 3) rotary: a) rotary-rotational; b) rotary-translational. A unit consisting of a pump (or several pumps) and a driving motor connected to each other is called a pump unit.

Gear pumps with external gearing - very wide range of drive shaft rotation speeds - wide range of operating pressures up to 30 MPa, volume up to 16.6 l/s - very wide range of viscosities of the working fluid - high level noise - average service life - low price

Blade hydraulic pumps Fig Vane (vane) pump series MG-16: 1 blade; 2 holes; 3 stator; 4 shaft; 5 cuff; 6 ball bearings; 7 drainage hole; 8 cavities under the blades; 9 rubber ring) 10 drain hole; 11 drain cavity; 12 annular projection; 13 cover); 14 spring; 15 spool; 16 rear disc; 17 box; 18 cavity; 19 hole for liquid supply with high pressure; 20 hole in the rear disc 21 rotor; 22 front disc; 23 ring channel; 24 supply hole; 25 housing - average range of drive shaft rotation speeds - average range of operating pressures up to 10 MPa, flow rate up to 4 l/s - average range of viscosities of the working fluid - low noise level - very long service life - average price

Radial piston hydraulic pump Diagram of a radial piston pump: 1 - rotor; 2 - piston; 3 - drum (stator); 4 - axle; 5 - suction cavity; 6 - discharge cavity - medium range of drive shaft rotation speeds - wide range of operating pressures up to 50 MPa, flow rate up to 15 l/s - medium range of viscosities of the working fluid - low noise level - very long service life

Axial piston hydraulic pumps inclined 1 - in the drive shaft; 2, 3 ball bearings; 4 rotary washer; 5 connecting rods 6 piston; 7 rotor; 8 spherical distributor; 9 cover; 10 central spike; 11 housing - wide range of drive shaft rotation speeds - very wide range of operating pressures up to 40 MPa, flow rate up to 15 l/s - very wide range of viscosities of the working fluid - high noise level - long service life - high price

Hydraulic distributors When operating hydraulic systems, it becomes necessary to change the direction of the flow of working fluid in its individual sections in order to change the direction of movement of the actuators of the machine, it is necessary to ensure the desired sequence putting these mechanisms into operation, unloading the pump and hydraulic system from pressure, etc.

Objective of the lesson: To develop knowledge about the water supply system and operation hydraulic devices; To develop knowledge about the water supply system and the operation of hydraulic devices; device and principle of operation of a hydraulic press; device and principle of operation of a hydraulic press; what determines the gain in strength; what determines the gain in strength; know the hydraulic press formula. know the hydraulic press formula.

How does atmospheric pressure change with increasing altitude above the Earth? How does atmospheric pressure change with increasing altitude above the Earth? Why does a balloon filled with hydrogen increase in volume as it rises above the Earth? Why does a balloon filled with hydrogen increase in volume as it rises above the Earth?

Water supply Diagram of the water supply system With the help of pump 2, water flows into a large tank of water located in water tower 1. From this tower, pipes are laid along city streets at a depth of approximately 2.5 m, from which special branches ending with taps go to each individual house .

Piston liquid pump Water is supplied to the water tower tank by pumps. These are usually electrically driven centrifugal pumps. Here we will look at the operating principle of another pump, the so-called piston liquid pump, shown in Figure 126. Water is supplied to the water tower tank by pumps. These are usually electrically driven centrifugal pumps. Here we will look at the operating principle of another pump, the so-called piston liquid pump, shown in Figure 126.

Design The design of the hydraulic press of the hydraulic press is based on the law. based on law. Pascal Pascal Two communicating Two communicating vessels are filled with a homogeneous liquid and closed by two pistons, the areas of which are S 1 and S 2 (S 2 > S 1). According to Pascal's law, we have equality of pressure in both cylinders: p 1 = p 2 vessels are filled with a homogeneous liquid and closed by two pistons, the areas of which are S 1 and S 2 (S 2 > S 1). According to Pascal's law, we have equality of pressure in both cylinders: p 1 =p 2 S 1). According to Pascal's law, we have equality of pressure in both cylinders: p 1 = p 2 vessels are filled with a homogeneous liquid and closed by two pistons, the areas of which are S 1 and S 2 (S 2 > S 1). According to Pascal's law, we have equality of pressure in both cylinders: p 1 =p 2">

When a hydraulic press operates, a gain in force is created equal to the ratio of the area of ​​the larger piston. When a hydraulic press operates, a gain in force is created equal to the ratio of the area of ​​the larger piston to the area of ​​the smaller one. to a smaller area. F2F2 F1F1 S2S2 S1S1

1. What force must be applied to a smaller piston with an area of ​​0.1 m 2 in order to lift a body weighing 500 N located on a piston with an area of ​​5 m 2? 2. What force must be applied to the smaller piston with an area of ​​2. What force must be applied to the smaller piston with an area of ​​0.1 m2 to lift a body weighing 200 kg located on a piston with an area of ​​10 m2? 0.1 m2 to lift a body weighing 200 kg located on a piston with an area of ​​10 m2?

What force must be applied to a smaller piston with an area of ​​0.1 m 2 in order to lift a body weighing 500 N located on a piston with an area of ​​5 m 2? Given S 1 =0.1m 2 F 1 =500H S 2 =5m 2 F2=?F2=?F2=?F2=? Solution F2=F2= F 1 · S 2 S 1 F2=F2= 500 N · 5 m 2 0.1m 2 = N Answer: N F1F1 F2F2 S1S1 S2S2 =

What force must be applied to a smaller piston with an area of ​​0.1 m2 to lift a body weighing 200 kg located on a piston with an area of ​​10 m2? Given S 1 =0.1m 2 m 2 =20 kg S 2 =10m 2 F1=?F1=?F1=?F1=? Solution F1=F1= F 2 · S 1 S 2 F1=F1= 1960 N · 0.1 m 2 10m 2 = 19.6 N Answer: 19.6 N F = m · g F 2 =200 kg · 9, 8 N/kg=1960N F1F1 F2F2 S1S1 S2S2 =

Homework: - ξ 44, 45, 4, s Make a working model of a hydraulic press (two syringes of different volumes, a straw for a cocktail)

A piston pump is one of the types of volumetric hydraulic machines in which the displacers are one or more pistons (plungers) performing reciprocating motion. Unlike many other positive displacement pumps, piston pumps are not reversible, that is, they cannot work as hydraulic motors due to the presence of a valve distribution system.

In the cylinder, under the action of the traction force (rod), the piston moves up and down. The piston thrust is passed through top cover through a flange with a rubber seal. Installed in the piston check valve. The same valve is also available in inlet pipe, which is connected to the bottom cover of the pump. When the piston moves down, water flows through the valve in the piston into the space above the piston (the lower valve is closed by water pressure). When the piston begins to move upward, water from the space above the piston begins to be displaced and pours into the outlet (outlet) pipe. At the same time, a vacuum forms under the piston space, the lower valve opens and water begins to be sucked up, following the piston. Then the cycle repeats.

Such pumps (hand pumps) can be used when groundwater(well or well) have a high water level. Those. the water is quite close to the surface of the earth. The maximum water depth limit for such pumps is 8 meters. Atmospheric pressure will not allow you to lift water from greater depths with such a pump. Currently, piston pumps are used in water supply systems, in the food and chemical industries, and in everyday life. Diaphragm pumps are used, for example, in fuel supply systems in internal combustion engines.