The distributor is a device designed to change the direction or start and stop the flow of the working medium in two or more lines depending on the availability of external control exposure.

Distributors are elements of a hydraulic system that allow you to change, open or close way of passing the flow of working fluid. Thereby managing the movement and stopping of the working elements of the hydraulic system.

Distributors are depicted in the diagrams of hydraulic installations according to GOST 2.781-68.

The conditional designations of the positions and channels of distributors are performed in accordance with the requirements of GOST (Table 1), while guided by the following basic rules:

Each position of the moving element of the distributor is depicted with a separate square;

Directions and ways of passing the flow of the working fluid in each position are denoted by arrows;

Locked inputs and outputs are denoted by a horizontal dash;

External hydrolynes, the flow in which is controlled by the distributor, are denoted in the images of the corresponding position as a feature;

The channel for removing the leaks of the working fluid is denoted by the dotted line and label on the circuits of the letter L.;

Each position of the distributor is denoted separately (the conditional designation is not stipulated by standards) in most cases letters but, b..... from left to right, and neutral position in the three-position distributor - zero (0).

Table 1 Passage designation in distributor channels

Figure 1 two-line two-position distributor

Depending on the constructive design of the shut-off-regulating element, the distributors are divided into spools (Fig. 1), valve (Fig. 2) and edge.

Figure 2 Constructive design and conditional image (does not match

GOST, but applied in some schemes) valve type distributor

Valve type distributors are often conventionally denoted in the samples with the image of the seat (Fig. 2), which is not provided for by standards. There are also variants of such valves with a neutral position (liquid duct from line Rin line BUT). A two-line two-position distributor is used to control the work of single-acting hydraulic cylinders (Fig. 3). There are also other possibilities for using a two-line two-position distributor (Fig. 4):

As a bypass valve, for example, in a diagram for switching from an accelerated movement to feed mode, or to enable liquid circulation with a non-free pump operation mode;

To connect and disconnect various hydraulic apparatus;

To control the hydraulic motor in one direction.

In a three-line two-position distributor (Fig. 5, 6), the work line is provided BUT, pressure line Rand plum lines T.connected to the hydraulicock. With this distributor controls the flow of fluid during switching to the following positions:

Neutral: Line Rclosed, line BUTconnected to the line T.;

Included: Drain through T.closed, flow from line Rin line BUT.

There are also three-line two-position distributors opened in a neutral position, i.e. flowing in this position Rin line BUT(Fig. 7).

Figure 3 Managing a single-sided hydraulic cylinder

Figure 4 Applications of a two-line two-position distributor:

a) non-pressure circulation of fluid supplied by the pump;

b) a diagram for switching from an accelerated movement to feed mode;

c) Scheme providing various pressure in the system.

Figure 5 Three-Line two-position distributor

In the four-line two-position distributor (Fig. 8, 9) there are two working channels. BUT, AT, one pressure Rand one drain, attached to the hydraulicock, line T.:

At neutral: stream from Rat ATand out BUTat T.;

In the included position: the stream from Rat BUTand out ATat T..

Figure 6 Single-sided hydraulic cylinder control

a) Circuit image of the distributor, b) the distributor in the context

Figure 7 Application of the distributor as a switch cooler heated fluid

Figure 8 Four-line two-position (4/2) Timber with three workers

belly.

Figure 9 Managing the work of the bilateral hydraulic cylinder

a) Circuit image of the distributor, b) the distributor in the context

There are also 4/2-dispensers, in which there are only two working belts (Fig. 10). Such devices do not require the connection of the line to remove the leaks of the working fluid, in view of the fact that these distributors canal T.connected to the hydraulicock and working channels BUTand ATpass through the drain lid. Therefore, considering that the pressure in the drain line T.affects the drain cover of the device, in technical passports of distributors of such a design maximum pressure in the line T.always set less than from the pressure side.

Figure 10 four-line two-position (4/2) Dispenser with two working belosties.

The most simple in design are 4/2 - spool-type distributors. The same distributors, but valve type, more expensive, as they have to collect from two three-line two-position distributors.

To select the desired distributor, the transitional positions of the spool are also important. Therefore, they are indicated in detailed conventional images in the diagrams (Fig. 11). But since it is not about the fixed positions of the distributors when switching them, then the corresponding frames for the intermediate position on the images are applied with a thin dashed line.

but) (Scheme number 574a) b)(Scheme number 574)

Figure 11 Transitional positions of the four-line two-position distributor. but) Conditional image: overlap when switching positively; b.) Conditional image: overlap when switching is negative.

Four-line two-position 4/2-dispensers (Fig. 8-11) are used to control:

Bilateral hydraulic cylinder;

Reversible hydraulic motors;

Two chains (contours) control.

Instead of a 4/2-dispenser, a 5/2-dispenser can also be applied (Fig. 12).

Figure 12 The scheme of application of a five-line two-position (5/2) distributor.

Figure 13 four-line three-position (4/3) Distributors with

various average positions.

Four-line three-position (4/3) spool type distributors (Fig. 13-18) are easy to design, while the similar valve type dispensers are complex and road.

For example, 4/3 - the distributor in the valve version can be collected from four separate two-line distributors.

Using a distributor of 64 schemes, you can include only one control circuit (Fig. 14-15). If you need to include multiple control circuits, then 4 / 3- distributor 64 of the circuit can also be applied to manage the operation of each of them (Fig. 15 b). In cases where the hydraulic installation is ready to switch to the operation of the pump without free operation, this switching is performed by 2/2-dispenser (Fig. 17).

The possible use of the four-line three-position distributor refers primarily the task of controlling the double-sided hydraulic cylinders or hydraulic modes (stop, rotation to the right, the rotation to the left). In 4/3 distributors, transitional positions are set (Fig. 18).

Presented in Figure 18 four-line three-position 4/3 - the distributor in the middle position has a positive overlap. The left and right transitional positions are a combination of positive and negative overlap types.

Picture. 14 scheme and position of the distributor Scheme number 64

Figure 15 Scheme providing non-free pump operation (idle

mode): a) Circuit image of the distributor, b) the distributor in the context.

Picture. 16 scheme and position of the distributor circuit number 44

Figure 17 Application example 4/3-distributor 44 Schemes

Features of the resolved management task determines the nature of the average position of the distributor. Multiposition apparatus can be structurally performed in the form of five-line distributors (Fig. 19).

Figure 18. Intermediate (transitional) positions 4/3-dispenser.

Figure 19 Scheme of five-line three-position (5/3) distributor.

Figure 20 Spool.

Output:studied the structural features of the hydraulic distributors; studied circuit images of distributors and features of their use in hydraulic schemes; Get the skill determination of the characteristics of the hydraulic distributors.

signal signal, the value of which is determined by the decoder output number, is fed to the encoder, and the converted code is installed at its outputs.

An example of using encoders is also the devices for entering binary codes into a digital device from the keyboard. When you press the key on a specific encoder input bus, logic 1 appears (the bus is excited) and the binary code is installed on the outputs, corresponding to the key-applied to the key (letter, digitite.).

3.5.2. Dispensers and switches

Distributors. A node that sequentially distributes from the output signals, which is sent, called distributor.

In fig. 3.25 The distributor functional diagram containing the counter and decoder is shown. Each pulse at the entrance of the meter increases the number fixed in it. Due to this, logical 1 alternately appears at the outputs of the decoder.

Distributors are used in solving various tasks. In particular, the signals from the distributor outputs can be made alternately on and disable devices, to receive signal samples at equal intervals. In the latter case, the samples are formed using a key managed by logical 1 from one of the distributor outputs and at the time of its operation connects the signal source to the line.

Switches. Switch - device switching chains. In fig. 3.26 depicts a switch diagram that allows you to connect the source of digital information D to

different channels (Y 1, Y 2, Y 3). Information will come to that channel

on the element and which resolution is supplied in the form of logical 1 from one of the address inputs A 1, and 2, and 3. The discussed switch is made on the same chip,

Fig. 3.25. Functionalthree elements I.

distributor scheme

Switch (Fig. 3.26) allows you to connect
channel Y to different sources of information
(D 1, D 2, D 3). Selection of an attached source
(switch entry) is carried out like
select channel in the previous scheme.
The task similar to the one that decides
switch (Fig. 3.26) performs multiplex
sorrow-switch in which the choice of entering it
number (address) is carried out using a digital
span signal (digital code).	Fig. 3.26. Scheme
In fig. 3.27 shows a functional scheme	desitator
ma Multiplexer. It contains conjunctures,

to which information tires are suitable, and a disjunctor. This multiplexer has eight informational (D 0 ... D 7) and three targeted (A 1 ... A 3) input. The address inputs receive a three-element digital code, the total number of combinations of which is 23, i.e. eight. It is natural to assume that code 111 must ensure the release of Y with the input d 7 (1112 \u003d 710), code 110 - with the input D 6 (1102 \u003d 610), etc., code 000 - with the input D 0.

Just as in the fig. 3.26, each input is connected to the output through a certain conjunctor. However, in this case, the switching is carried out in the presence of three resolution logical units at the conjunctor (from three address inputs). To obtain them, the inputs of the corresponding conjunctor must be connected directly to those targeted inputs, at which there are units at this code, and through the inverter-storms on which zeros are located. Such compounds are made in the diagram (Fig. 3.26).

So, on the second topFig. 3.27. Multiplexer switch diagram

the conjunctor directly arrives from the input A 1 and through the inverters - from the inputs A 2 and A 3, which, with the code 001, will provide three logical on this conjunctor1, i.e. Connecting ModeMultiplexer input D 1. The lower conjunct inputs are connected to the address inputs directly that when the address of the address 111 will provide a connection to the output of the multiplexerinforming data.

The domestic industry produces several types of microcircums multiplexers. In fig. 3.28 shows a conventional image of a multiplexer

Fig. 3.28. Conditional(Microcircuit of the K155 series) having multiplexer injuryseven information entries, three ad-

rash inputs for codes with weights 4, 2, 1, gating input A and two outputs - direct and inverse. If there is a logical one at the input, the multiplexer is blocked: logical 0 is installed on the direct output, regardless of the potentials at information inputs. The presence of gating input allows you to increase the number of switched information inputs.

3.5.3. Digital comparator

The digital comparator is designed to determine the equality of binary numbers.

Two numbers are equal to the equality of numbers in the discharges of the same name (and i \u003d B i, where a i is a digit in the i -M discharge of one number; B I is a digit in the same discharge of another number).

Equality A i \u003d Bi takes place at a i \u003d 1, bi \u003d 1 or when and i \u003d 0, bi \u003d 0. Therefore, a logical function expressesing this equality is equal to one if one is equal to the product of these numbers or the product of their inverse values : y \u003d Aibi + Aibi. Note that the recorded function is the "Equality" function.

a1 b1 a1 b1 ... an bn a n bn \u003d y,

where the denial of the left side (when changing in the right part y on y) is done for the same purpose.

The scheme implementing this expression is shown in Fig. 3.29, a. If it is necessary that with the equal code at the output of the comparator, there was a logical 1, then the inverter should be connected to the circuit output.

The conditional image of the digital comparator is shown in Fig. 3.29, b.

Hydraulic distributor is a device that serves to change the flow directions of the working fluid in the hydraulic engine, in the presence of an external signal.

Switching distributor can be changed with hydraulic lines compound, directing the working fluid to the selected hydraulic units.

Types of hydraulic distributioners

Depending on the type of valve and adjusting element, valve and spool distributors are distinguished.

• Sladen
  • Direct action
    • Manual control
    • Mechanical management
    • Electric control
    • Hydraulic control
    • Pneumatic management
  • Indirect action
• Valve
  • Direct action
    • Manual control
    • Mechanical management
    • Electric control
    • Hydraulic control
    • Pneumatic management
  • Indirect action
    • Electrohydraulic management

Slot distributors

Valve distributors provide better tightness, they are able to operate with greater pressure than spool.

Splitzer distributors are more compact, they allow you to provide smooth overlap of working windows, which is important in the presence of large inertial masses.

Consider a detail the device, characteristics and principle of operation of spool distributors who have received widespread.

Number of the positions of the hydraulic distributor

The number of variants of the embodiment of the hydrolynes of the distributor is called the number of position. Two and three-position distributors received the greatest distribution.

Neutral Call a position in which the spool is installed in an inactive state under the influence of the reasons forces (for example, the spring force).

The number of summed lines

The distributors may vary by the number of lines of lines, four linear hydraulic distributors are most often used, 4 lines are supplied to them:

• p - pressure
• t - plum
• a - Output A (for example, the supply of fluid into the piston cavity)
• b - yield B (for example, supply of the working fluid into the rod cavity of the hydraulic cylinder)

Device and principle of operation of the hydraulic distributor

Consider the device of a four-liter three-position distributor locked in a neutral position.

The principle of operation of the hydraulic distributor 44 schemes is demonstrated on video.

In the dispenser's case, there are channels for the supply of fluid. The spool is installed in the hole, bold in the case.

Spool distributor - Detail, usually cylindrical, on which believes, grooves, grooves needed for separating or connecting different channels made in the distributor housing.

In the neutral position, the spool is held with the help of springs, at this point it locks the line R. in the presence of a control signal, the electromagnet 1 moves the spool to the right. In this position, the spool connects the channels p and a, t and b. In the absence of a control signal, the springs will be returned to the neutral position. In the presence of an electrical signal on the electromagnet 2, the spool moves to the left, connecting the channels P and B, T and a.

Hydraulic distributors control methods

According to the control method, hydraulic distributors with mechanical, manual, electromagnetic, hydraulic pneumatic control are distinguished. In Guest 24679-81 indicated diameters of conditional aisles of hydraulic distributors - 6, 10, 16, 20, 32 mm. Combined conditional passages and control methods are noted in the following table.

Designations of hydraulic distributors

In the designation of the distributor, the fraction indicates the number of main lines summarized to the distributor, and position. for example four-line three-position distributor Will be marked 4/3. Also in the designation of the distributor indicates the number of the circuit number (see the table below).

Hydraulic distributor scheme

On the hydraulic diagram, the hydraulic distributor is indicated by a number of rectangles, each of which indicates a separate position of the distributor.

In each rectangle, the lines show what channels will connect the distributor in this position.

According to GOST 24679-81, the following are issued. schemes of hydraulic distributors.

Distributors 64, 44, 574, 34 schemes are one of the most common. The distributor of 64 schemes in a neutral position allows you to unload the pumping station by sending the working fluid to the drain.

The main performances of the hydraulic distributors

Using the data presented in the table, we can conclude a compliance of the distributors schemes:

• 14 Scheme on Russian classification correspond to ATOS 0710 distributors, Duplomatic S2, Parker 2C, Caproni 00, Rexrot H
• 24 Scheme correspond to ATOS 0718 distributors, Duplomatic S10, Parker 6C, Caproni 05, Rexrot M
• 34 Scheme correspond to ATOS distributors 0713, Duplomatic S3, Parker 4C, Caproni 04, Rexroth J
• 44 Scheme correspond to ATOS 0711 distributors, Duplomatic S1, Parker 1C, Caproni 01, Rexroth EB
• 64 Scheme correspond to dispensers, ATOS 0714, Duplomatic S4, Parker 9C, Caproni 02, Rexroth G, etc
• 574 Scheme correspond to ATOS 0630/2, Duplomatic TA002, Parker 30B, Caproni 11, Rexroth C

The distributor of the P-40 of this modification is intended for use in hydraulic systems of machines, equipment, tractors and special equipment in places where long-term operations are required. Calculated on Nominal oil with a flow of up to 40 liters per minute, maximum pressure up to 25 mP (250bar).

The hydraulic distributor is controlled by mechanical, handles that are fixed in three conventional positions: "Lifting", "neutral", "lower". Please note that the handles do not have an automatic return to the neutral position (the operation is turned off manually by returning the handle to the middle position).

P-40 hydraulic distributor Designed to change the direction of flow, restrictions on the pressure of the working fluid in hydrolynes, unloading the pump in the neutral position of the spools.

It is used in hydraulic systems of various types of equipment, including: excavators, drill vehicles, loaders, truckrants, agricultural machines, construction, road, utility technician, suggestions, wood cutters, etc. with feeding up to 40 liters / min. (Hydraulic systems with NSh-8/10/14/16, 310.12 pumps, as well as 310.28 and NSh-32 when limiting revolutions).

P related HydroShorts of imported production (European Union). Guaranteed high quality and long service life.

It offers a wide range of spare parts for special equipment and hydraulic components. Always in stock Most commodity positions. Accessible prices, flexible discount system. When buying, we provide professional advice to the buyer about the use of purchased parts purchased, other consultations.

Chapter 4.

Dispensers

4.1. Main types of distributors
Distributors are devices designed for starting, stopping and changes in the direction of flow of compressed air. The limited designation of the distributor provides information on the number of lines (channels) for air passage, the number of switching positions and the type of control. This image, however, does not give an idea of \u200b\u200bthe design of the distributor, but indicates only its functionality.

Behind position rest the position of switching the distributor with a self-interacting return device is accepted, for example a spring, which is occupied by moving parts of the distributor, if it is not under the influence of the control signal. Source position the switching position is called that the movable parts of the distributor receives after its installation on the installation and inclusion of energy sources (power with compressed air and (or) by electrical current) and with which the provided progress program (sequence) begins.

The design of the distributor has a significant impact on its characteristics such as service life, switching time, switching force, control method, types of connections to pipelines and sizes.

According to constructive execution, distributors with locking elements are distinguished:

Valve (saddle) type:

Ball,

Tarbed (flat);

Sliding type:

With a cylindrical spool

With a flat spool

With an end spool.

Valve (saddle) type dispensers

In these distributors, the compressed air passage channels open and close by means of ball, disk, disk or conical shut-off elements that interact with the saddles of the corresponding form. The seal on the contact area of \u200b\u200bthe locking element with the saddle is usually achieved through the use of elastic materials at the point of contact. In the valve (saddle) distributors, there are almost no details subject to wear (there are no friction pairs), so they have a long service life. In addition, they are also insensitive to pollution and can work in adverse conditions. However, to switch such dispensers, a significant effort is necessary to overcome the effect of the return spring or return pressure.

Split-type distributors

In these distributors, individual channels are connected or separated by cylindrical, flat or end spools.

4.2. 2/2-dispensers

2/2-distributor has two air supply lines / dumping and two switching positions. It is mainly used as a shut-off (shut-off) distributor, as it realizes only the function of overlapping or opening the passage of air through itself, without having the ability to remove air to the atmosphere in the closed position (unlike 3/2-distributor).

4.3. 3/2-Distributors

Using a 3/2-dispenser, you can turn on and off the air flow. The 3/2-dispenser has three lines of supply / removal of air and two switching positions. Additional, compared to 2/2-dispenser, exhaust channel 3 (R) allows you to disconnect the signal at the exit of the distributor, connecting it with the atmosphere. In a normally closed distributor in the original position, the ball valve under the influence of the spring overlaps the air duct from the power line 1 (P) to the output channel 2 (a). Channel 2 (A) is connected through the hole in the pusher and the channel 3 (R) with the atmosphere.

Fig. 4.1. 3/2-dispenser, normally closed, with ball valve element
Under the influence of external force, the pusher presses the valve ball, overcoming the return spring and the opposing compressed air pressure.

In the power on the channel 2 (a) cut off from the exhaust channel 3 (R), the return spring is compressed and the ball departs from the saddle, opening the air duct from the power channel 1 (P) to the channel 2 (a), and a pneumatic signal appears at the exit of the distributor . If you eliminate the impact on the pusher, the distributor will return to its original position. In this case, the distributor has manual or mechanical control. The control force required to switch the dispenser depends on the power pressure value, the power of the spring and friction forces in the distributor. This force limits the dimensions of the distributor, because with increasing flow section, the control force also increases. The design of the distributor with a spherical valve shutter is very simple and compact.

In the diagram (Fig. 4.2) 3/2-distributor 1.1 controls the movement of a single-sided cylinder string 1.0. In the original position, the power supply channel 1 (P) of the distributor is blocked, but when you press the button, the distributor switches and the supply channel 1 (P) is connected to the channel 2 (a) to which the cylinder cavity is connected. A compressed air begins to flow into it, forcing the piston to move, squeezing the return spring installed in the ride cavity of the cylinder. If the button is released, then under the action of the spring, the distributor returns to the initial position in which the channel 2 (A) is connected via the channel 3 (R) with the atmosphere, the releasing air from the piston cylinder cavity. The piston of the cylinder under the action of the return spring is drawn by occupying the starting position.

Fig. 4.2. Schematic diagram: Single-acting cylinder management


Fig. 4.3. 3/2-dispenser, normally closed, with a plate-type valve, in the "Disabled" position
3/2-dispenser, represented in Fig. 4.3, performed on the basis of a plate (disk) valve. It provides a simple and efficient seal between the locking element and the seal. Switching time is small, since such a valve with a small movement provides a large passage section. As well as a distributor with a spherical locking element, such a distributor is insensitive to pollution and has a long service life. 3/2-dispensers are used in control systems with single-acting cylinder or to generate input signals of control dispensers.

Fig. 4.4. 3/2-distributor, normally closed, with a plate-type valve, in the "enabled" position
The normally open 3/2-dispenser opened a compressed air passage from a power channel 1 (P) to channel 2 (a). In this position, the channels 1 (P) and 2 (A) are connected to each other through the channel in the shut-off element, while the latter, holding the spring on the saddle, blocks the exhaust channel 3 (R). When exposed to the pusher, it first, entering into contact with the locking element, blocks the power channel 1 (P), and then, pulling the shut-off element from the saddle against the power of the spring, opens the pass from the channel 2 (A) to the exhaust channel 3 (R) . When removing the impact from the pusher, at first, the more powerful spring of the locking element without disturbing it to its pusher planting it on the saddle, blocking the channel 3 (R), and then the pusher spring returns its whistle, opening the passage from the power channel 1 (P) to the channel 2 (A).

Control 3/2-dispensers can be manual, mechanical or pneumatic. The control depends on the requirements of the control system.

Fig. 4.5. 3/2-distributor, normally open, with a plate-type valve, in the "Disabled" position


Fig. 4.6.3 / 2-distributor, normally open, with a plate-type valve, in the "Inclusive" position
On the presented scheme, a normally open 3/2-dispenser is used, which in the initial position sues compressed air into the cylinder cavity of one-sided action 1.0. Therefore, the cylinder rod in the initial position is extended. When exposed to the pusher 1.1, the operating volume of the cylinder through the channels 2 (A) and 3 (R) is connected to the atmosphere. The cylinder rod 1.0 under the action of the return spring is retracted.


Fig. 4.7. Schematic diagram: Single-acting cylinder management
3/2-spool-type dispenser with double-sided manual control

The design of the distributor is very simple and compact. The distributor has two fixed positions - open and closed. When manually shifted, the spool having a view of the sleeve on the pipeline, the power channel 1 (P) is connected to the output channel 2 (a). With the return switching channel 2 (a), it is reported to the atmosphere through the channel 3 (R), the compressed air is removed from the system. Such a distributor is used to connect the power of pneumatic system with compressed air.

Fig. 4.8. 3/2-zero-type spool-type distributor, normally closed
3/2-Distributor with pneumatic control

The distributor has a heading piston and a return spring. At rest, the distributor is closed normally, since the power channel 1 (P) is blocked by a disk locking element, and the output channel 2 (a) is connected by means of a channel 3 (R) with an atmosphere. The distributor switches to its input 12 (z) compressed air pressure attached to the control piston. In this case, the channel 1 (P) is connected to the channel 2 (a). After removing the pressure in the control channel 12 (z), the distributor returns under the action of the return spring to the initial position (resting position). The valve disconnects the channels 1 (P) and 2 (A). The output channel 2 (A) is connected via the channel 3 (R) with the atmosphere. 3/2-dispenser with one-sided pneumatic control and a return spring is performed normally closed and normally open.

Fig. 4.9. 3/2-dispenser, with pneumatic control and return spring, in the "Disabled" position


Fig. 4.10. 3/2-dispenser, with pneumatic control and return spring, in the "Inclusive" position

Fig. 4.11. Schematic diagram: indirect cylinder control of one-way action
A pneumatic control dispenser can be used as an input element with indirect cylinder control. The indirect control signal for the extension of the stem cylinder 1.0 (Fig. 4.11) is supplied with a 3/2-hand-controlled distributor 1.2 to the control distributor 1.1, when the cylinder rod 1.0 is put forward.
The design of the distributor under consideration is designed in such a way that to convert a normally closed 3/2-distributor to the distributor normally open, it is only necessary to invert (mutually change in places) Channels 1 (P) and 3 (R), A control head with a channel 12 (z) Rotate 180 °. You should also assign a new designation to the control channel: 10 (z).

If a normally open distributor is installed in the non-varying control system considered above, then in the original position, the piston rod will be extended. After pressing the pneumatic button 1.2, the cylinder rod turns.

Fig. 4.12. Schematic diagram: indirect cylinder control of one-way action
3/2-dispenser with indirect lever control with roller

Preliminary reinforcement distributors allow you to reduce management force. Dispossets with indirect control cascade are called indirect control dispensers, and an element of control that performs a pre-cascade of amplification - a pilot valve (or a pilot spool). Power pressure is supplied to the pilot valve (Fig. 4.14). If you press the roller lever, the pilot valve opens. Compressed air affects the membrane, which moves the barbed locking element of the main valve down. In this case, the process of serial switching 3/2-dispenser occurs: first interrupted the connection of the channel 2 (a) with the channel 3 (R), and then the channel 1 (P) is connected to the channel 2 (A).

Fig. 4.13. Indirect control element: on the left turned off, on the right is on
Returns the distributor to its original position occurs after the lever is released with the roller. Due to this, the pilot valve is closed. The air from under the membrane follows through the channels of the guide tracting of the pilot valve pusher. The control piston of the main valve under the influence of the return spring occupies the starting position.

Fig. 4.14. 3/2-dispenser with indirect control from the lever with a roller, normally closed
The design of this distributor allows you to apply it as normally closed and as a normally open distributor. It is designed in such a way that the power supply channel 1 (P) and the exhaust channel 3 (R) can be changed in places, and the control head with a channel 12 (z) can be rotated 180 °.
Distributor with a leaving lever with roller

The distributor with the control of a broken lever is activated only if the switching pusher affects the roller in one particular direction. The distributor is installed as a finite switch to survey the position of the retractable and extending cylinder rod. At the same time, it is necessary to draw attention to the fact that the valve during installation should be oriented in such a way that it is included only with the desired direction of movement.

The design of this distributor also allows you to apply it as normally closed and as a normally open distributor. It is designed in such a way that the power supply channel 1 (P) and the exhaust channel 3 (R) can be changed in places, and the control head with a channel 12 (z) can be rotated 180 °.


Fig. 4.15. 3/2-dispenser with indirect lever control with roller, normally open
4.4. 4/2-dispensers

The 4/2-dispenser has 4 air supply / removal channels and 2 switching positions.

Fig. 4.16. 4/2-dispenser with a plate locking element, "Disabled" position
4/2-distributor performs the same functions as a combination of two 3/2-dispensers, one of which should be normally open and the other is normal closed.


Fig. 4.17. 4/2-dispenser with a plate locking element, "Inclusive" position
With a simultaneous impact on both pushers, the passages between the channels 1 (P) and 2 (B) overlap and between the channels 4 (A) and 3 (R) overlap. As the pushers are further transferred, together with the valve locking elements against the power of the springs, there are passages between the channels 1 (P) and 4 (A) and between the channels 2 (B) and 3 (R).

After removing the control exposure to the pushers, the distributor returns to its original position under the action of a return spring. 4/2-dispensers are used to control bilateral cylinders.

There are also 4/2-permissors with one-sided pneumatic control and a return spring, with double-sided pneumatic control, with an indirect control from the roller lever. Flat or cylindrical spools can be used as the distribution organ. As a rule, 4/2-distributors perform the same functions as 5/2-dispensers.

Fig. 4.18. Schematic diagram: direct control of a bilateral cylinder
In flat-star distributors, the switching of supply / removal channels is switched on a flat surface with a flat locking element sliding. The shut-off element is driven by the control piston, rigidly connected to it.

Fig. 4.19. 4/2-dispenser with double-sided pneumatic and flat spool

The distributor considered is direct bilateral pneumatic control. When removing the control pressure, the control piston, together with the locking element, remains in the position-busy position until the new control signal arrives from the opposite control channel.

4.5. 4/3-distributors

The 4/3-dispenser has 4 channel supply / removal channels and 3 switching positions. An example of such a distributor can serve as a flat-crane distributor equipped with manual or foot (pedal) control. When the plane crane is rotated with the batteries made in it, there is a connection of input and output channels.

Fig. 4.20. 4/3-dispenser with manual control, in neutral position is closed

Fig. 4.21. 4/3-hand-controlled dispenser, cross-section
On the constructive scheme (Fig. 4.21), 4/3-distributor is shown, in which all channels are blocked in the middle position and are not connected to each other. This allows you to stop the bilateral cylinder rod in any position in the course of its movement, although such an intermediate position cannot be provided with sufficient accuracy. Due to the compressibility of the air when the load is changed, the piston will dwell each time in different positions.

Fig. 4.22. Schematic diagram: direct control of a bilateral cylinder
4.6. 5/2-dispensers

5/2-dispenser has 5 air supply / removal channels and 2 switching positions.

It is used mainly as a control element of pneumatic control with bilateral cylinders. An example of such a distributor can serve a distributor with a cylindrical spool as a moving locking element. Switching and overlapping of the corresponding channels occurs during the axial shift of the spool. In contrast to distributors with ball and plate locking elements, the control force in them, acting on the shovel ends on the squeezed air or a return spring, is small due to the small forces of resistance. To control the distributor with a cylindrical spool, all types of control can be applied - manual, mechanical, pneumatic or electric. To return the distributor to its original position, the same types of management are used.


Fig. 4.23. 5/2-dispenser with double-sided pneumatic control
Control movement in spool distributors more than valve. In addition, the solution of the seal problem is complicated in cylindrical spools. As they say, the compaction of the type "metal for metal" requires an accurate fit of the cylindrical spool to the hole in the housing or the sleeve.

The gap between the spool and the body should be in the pneumatic distributor, if possible, less, because otherwise too large leaks are possible. The actual radial gap value is in the range of 0.002 ... 0.004 mm. In order to somehow reduce the cost of producing spool steam, the allowable gap is somewhat increased, and the spool or body is supplied with sealing rings from an elastic material. Compacts in the form of round rings or cup cuffs can be installed on a spool, and round rings ■ to the housing. In order to avoid damage to the seals, the distributor channels are located along the circumference of the spool sleeve (housing).

Fig. 4.25. Schematic diagram: indirect control of bilateral cylinder

5/2-Distributors are usually installed in the system instead of 4/2-dispensers. 5/2-dispenser allows you to remove air from the cylinder working cavities along various exhaust channels when extending and pulling the rod. The control functions of 4/2 and 5/2-dispensers are mostly the same.

A dispenser with double-sided pneumatic control of the spool type can be equipped with a sealing element in the form of a plate truck valve having a relatively small switching course. Tarbed seat valves, placed on the spool, connect the channel 1 (P) with channel 2 (b) or 4 (a). And the valves placed on the piston open or closed the exhaust channels accordingly. In addition, the distributor on both sides has manual control.

Fig. 4.25. 5/2-dispenser with double-sided pneumatic control and auxiliary manual control, with a plate-type stop element; Opened air duct from channel 1 to channel 2
5/2-dispenser with double-sided pneumatic control has a memory property. The distributor is controlled by alternating a pneumatic signal to control channels 14 (z) and 12 (y). The switching position is saved and after removing the control signal until the control signal is filed from the opposite side of the distributor.


Fig. 4.26. 5/2-dispenser with double-sided pneumatic control and auxiliary manual control, with a plate-type stop element; Opened duct air from channel 1 to channel 4
4.7. 5/3-distributors

The 5/3-dispenser has five operating channels for air supply / removal and three switching positions. With the help of such distributors, you can stop the piston of the bilateral cylinder anywhere along the rod. In this case, in the neutral position of the distributor, the cylinder piston stops under the action of a short-term increase in pressure, and the movement of the piston begins with a reset of pressure in the corresponding cylinder cavity. If the control signal is absent in both control channels, the spool is held in a neutral position using centering springs.

Fig. 4.27. 5/3-dispenser with bilateral pneumatic control; In neutral position, all channels are blocked
4.8. Expenditure characteristics of the distributor
When choosing a distributor, the user must first pay attention to pressure loss and air flow passed by a pneumatic distributor. The selection of the distributor is determined:

The volume and speed of the piston of the cylinder,

Required frequency of switching,

Permissible pressure losses.

Pneumatic distributors are characterized by their nominal flow.

When calculating the amount of consumption, the following are taken into account

variables:

p1 - Pressure at the input of the distributor (kPa or bar),

p2 - pressure at the exit of the distributor (kPa or bar),

ΔР - Purpose Pressure (P1 - P2) (KPA or Bar),

T1 - Temperature (K),

qn - nominal flow (l / min).

The distributor is tested by run through it air in certain directions. In this case, the inlet and output pressure of the air is measured. According to measurements of the mass of the air transmitter, the nominal flow is determined.

Information about nominal distribution consumption can also be found in manufacturers' directors.

4.9. Reliability of distributors

The reliability of the system management to a certain extent depends on the method of fastening the limit switches. The limit switches should be constructed in such a way that their easy installation and attachment is provided. This is important to accurately determine the position of the cylinder rod.

Installation of distributors

In addition to the correct selection of the type of distributors, their installation is also affected by their installation, on which the switching characteristics, trouble-free operation and the possibility of access for repair and maintenance. This applies both to distributors supplying power to cylinders and to distributors performing logical and computing or informational functions.

Facilitate maintenance and repair work facilitate:

Numbering system elements,

Installation of optical indicators,

The presence of a complete set of documentation.

Installation of dispensers with lever control with roller

Usually manual control dispensers used to enter signals are installed on the remote control or control panel. Therefore, it is convenient to use replaceable control heads on the body of the distributor design. To perform a wide variety of options for entering signals, there are various designs of control heads.

Distributors as control elements (power amplifiers) determine the workflows of pneumatic actuating devices. The main requirement for controlling distributors, which are used to manage the actuators, is to ensure the rapid reverse of the latter when applying a new control signal. Therefore, such distributors should be located, if possible, near the executive devices, to shorten the length of the pipelines, and therefore, the switching time of the devices themselves. In the perfect case, the distributor must be installed directly on the actuator, the movements of which it controls, as a result of which the number of intermediate connections and the length of pipelines is reduced, and the system installation time is significantly reduced.