RU2095640C1 - Hydraulic lock - Google Patents

Abstract

FIELD: mechanical engineering, hydraulic drives of processing lines and lifting mechanisms. SUBSTANCE: hydraulic lock has housing, shutoff valve forming above-valve and under-valve spaces and first control piston engaging through rod with shutoff valve and forming first control chamber together with housing. Spring-loaded valve with central hole is installed in shutoff valve coaxially with valve at side of above-valve space. Adjustable restrictor with working tip is installed in housing. Working tip is fitted in above indicated hole with radial clearance through which above-valve and under-valve spaces are placed in communication when valve is opened. EFFECT: enhanced reliability of operation. 4 cl, 3 dwg

Description

 The invention relates to mechanical engineering, namely to hydraulic drives, and is intended for use in hydroficated technological lines and lifting mechanisms used in industry, construction and transport.

Known hydraulic locks designed for free (without resistance) transmission of the flow of the working fluid to the hydraulic motor, for fixing the hydraulic motor and for the free flow of the working fluid from the hydraulic motor in the presence of control pressure [1,2]
The closest in combination of essential features with the proposed device is a three-line one-way hydraulic lock (for example, type KU, version 4 and 2, manufactured by the Gryshinskiy software "Hydraulic Unit"), which is adopted as a prototype [3] The known hydraulic lock contains a housing, a shut-off valve, forming in the body, the supravalve and subvalve cavity, and a control piston with a rod interacting through the said rod with a shutoff valve on the side of the subvalve cavity and forming a control chamber with the housing. Distinctive features of such a hydraulic lock are, firstly, the presence of one control piston and one control chamber and, secondly, ensuring the free flow of working fluid from the supravalvular cavity into the subvalvular cavity when pressure is applied to the control chamber and the shut-off valve is opened.

 A disadvantage of the known hydraulic lock is that its use in hydraulic drives causes insufficient reliability of the operation of these drives, which in turn can lead to an emergency. In addition, the use of known hydraulic locks causes an increase in the overall dimensions of the drives. This statement can be confirmed by the following examples.

 In a number of lifting mechanisms and production lines, it is necessary to carry out multiple movements (rises and lowerings) in an arbitrary sequence of two objects, for example, carriages, each of which is connected with its own executive cylinder. However, it is necessary to exclude the possibility of simultaneously lifting both cylinders to the full extent of their working strokes, since in such a situation a carriage collision will occur. The corresponding hydraulic system for moving the carriages contains a pump, two reversing distributors and two three-line one-way hydraulic locks, the valve valves of which are connected to the working cavities of the actuating cylinders through throttles with non-return valves. The output channels of one distributor are connected to a subvalve cavity and a control valve of a hydraulic lock connected to the first cylinder, and the output channels of another distributor to a subvalve cavity and a control chamber of a hydraulic lock connected to a second cylinder. When switching the distributor, the corresponding cylinder rises and falls. The lifting mechanism is equipped with a control electrical system with limit switches in contact with the carriages when the cylinders are on the final section of their working strokes. If, as a result of the operator’s erroneous actions, one cylinder is lifted to the full extent of its working stroke with the rod of the other cylinder fully extended, then the control electrical system stops the lifting operation by the total signal of the limit switches by issuing a command to return the valves to their original position or to put the pump in idle mode . In the event of a limit switch malfunction, an open circuit in the control system, and a lack of power, the operator’s erroneous actions cause an emergency carriage collision. In addition, equipping the lifting mechanism with a control electric system leads to an increase in its overall dimensions and cost.

 Another example. Many hydraulic systems of technological equipment contain an actuating cylinder and a one-way hydraulic lock connected with their nadklapannym cavity to the specified cylinder (see. N. Dobrinsky "Hydraulic drive presses. M. Engineering, 1975, Fig. 100, 101 and 103). A throttle is included in the line connecting the subvalve cavity of the hydraulic lock to the tank, designed to limit the speed of lowering the loaded cylinder. In parallel with the throttle, a check valve is installed, which is necessary for the free passage of the working fluid to the cylinder when it is raised. In the process of operating technological equipment, the throttle may be in the open position due to erroneous actions by the operator, the integrity (destruction) of the line connecting the throttle to the undervalve hydraulic lock cavity before lowering starts. In these cases, when pressure is applied to the control chamber of a known hydraulic lock (to perform the operation of lowering the cylinder under load), an emergency situation will occur when the object falls within the cylinder stroke. The disadvantages of these hydraulic systems containing known one-way hydraulic locks include the significant volumes they occupy, which is due to the need to place elements such as a throttle valve, a non-return valve and an associated pipeline network.

 The problem solved by the invention is to increase the reliability of hydraulic systems with hydraulic locks, as well as reducing their weight and size parameters.

 The solution to this problem is provided by the fact that in the known hydraulic lock containing a shut-off valve, forming a valve and a sub-valve cavity in the hydraulic lock body, and a control piston interacting through the stem with a shut-off valve from the valve side and forming a control chamber with the housing, according to the invention, in the housing On the side of the control chamber, a second control piston is installed, interacting through the rod with the first control piston and forming a second control chamber in the housing. The use of the proposed hydraulic lock in lifting mechanisms makes it possible to exclude from their composition control electrical systems with limit switches, which increases the reliability of these mechanisms and reduces their overall dimensions.

 A spring-loaded valve with a central hole can be installed coaxially with the latter in the shut-off valve, coaxially with the latter, and a throttle with a working tip installed in the hole with a radial clearance that communicates the shut-off and under-valve cavities with the shut-off valve open is installed in the casing. A hydraulic lock of this design replaces 4 traditional hydraulic elements: a well-known hydraulic lock and a parallel throttle, a check valve and a shut-off valve, which is necessary to quickly empty the slave cylinder. The network of hydraulic pipelines is also simplified. When using such a hydraulic lock, violation of the integrity (destruction) of the line connecting the subvalve cavity of the hydraulic lock to the tank does not lead to the fall of the object during its lowering.

 The second control piston has a stroke less than the stroke of the first control piston, and the area of the second control piston is larger than the area of the first control piston. This eliminates the possibility of the object falling during its lowering due to erroneous operator actions.

 The throttle can be made adjustable, which allows the lowering of objects with different masses in optimal speed mode. This reduces the total time of lowering operations.

 To improve the manufacturability of the proposed hydraulic lock, reduce its cost and facilitate the installation of the optimal lowering speed, the working tip of the throttle can be made in the form of a reverse cone. In this case, the central opening of the spring-loaded valve has a cylindrical shape.

 A similar effect is achieved when the working tip of the throttle is in the form of a stepped cylinder. In this case, the specified Central hole has a conical shape.

 In FIG. 1 and 2 are structural diagrams of the proposed hydraulic lock with hydraulic systems; in FIG. 3 embodiment of the working tip of the throttle lock.

 The hydraulic system shown in FIG. 1 contains two proposed hydraulic locks. The hydraulic lock 1 contains a housing 2, in the upper part of which a shut-off valve 3 is located, forming a supravalvular cavity A and a subvalvular cavity B. Radial windows 4 and longitudinal grooves 5 are made in the shut-off valve 3, which serve to connect these cavities when this valve is open. In the middle part of the housing 2, a first control piston 6 is placed, which forms with the housing 2 a first control chamber B and interacts via a stem 7 with a shut-off valve 3. The subvalvular cavity B and the stem cavity G are connected to each other. In the lower bore of the housing 2 from the side of the first chamber B, a second control piston 8 is installed, which interacts through the rod 9 with the first control piston 6 and forms a second control chamber D. with the body 2. The first chamber B and the rod cavity G are connected to each other. Using the springs 10 and 11, the control pistons 6, 8 and the rod 9 are held in their original lower position. Using the spring 12, the shutoff valve 3 is pressed against its seat, and the rod 7 is held in its original lower position.

 The hydraulic lock 13 is made in a similar manner.

 The supravalve cavities A of the hydraulic locks 1 and 13 are connected via throttles with check valves 14 and 15 to the actuating cylinders 16 and 17, which serve to move (raise and lower) the inclined plane of the loaded carriages 18 and 19. Chokes with check valves 14 and 15 are designed to limit the lowering speed of the carriages 18, 19 and for the free passage of oil to the actuating cylinders 16, 17 when lifting these carriages. The cylinders 16, 17 with the carriages 18, 19 are arranged in such a way that, when the cylinders 16, 17 are simultaneously extended to the full extent of their working strokes, there will be a collision (collision) of these carriages. Reversible valves 20 and 21, which serve to raise and lower the cylinders 16 and 17, are connected with their inlet holes to the pump 22 and the safety valve 23, designed to protect the hydraulic system from overloads. One outlet of the reversible distributor 20 is connected to a subvalve cavity B of the hydraulic lock 1 and to the first control chamber B of the hydraulic lock 13, and the other outlet to the subvalve cavity B of the hydraulic lock 13 and with the first control chamber B of the hydraulic lock 1. The outlet openings of the reversible distributor 21 are connected to the second control chambers D of hydraulic locks 1 and 13. To these chambers D through check valves 24 and 25, a bypass valve 26 is connected, which allows to reduce power consumption when lowering the carriages 18 and 19. Pressure setting the valve Pan 26 is determined by the pressure in the over-valve cavities A of the hydraulic locks 1, 13 from the weight of the loaded carriages 18, 19 and the ratio of the area of the second control piston 8 to the area of the seat of the shut-off valve 3. The larger this ratio, the lower the pressure of the bypass valve 26. The hydraulic system includes also filters and a pump discharge device (not shown).

 The hydraulic lock 27 (see Fig. 2) is structurally similar to the hydraulic locks 1, 13 and additionally contains a spring-loaded valve 28 with a central hole 29 installed in the shut-off valve 3, and a throttle 30 with a working tip 31 installed in the housing 2. The working tip 31 is located in the Central hole 29 with a radial clearance, which serves as a throttle gap, limiting the flow of oil through the hydraulic lock 27 in the process of lowering the load. When the shut-off valve 3 is open, the supra-valve cavity A communicates with the sub-valve cavity B through the specified throttle slot, the radial windows 32 of the spring-loaded valve 28, the radial windows 4 of the shut-off valve 3 and its longitudinal grooves 5. When the spring-loaded valve 28 is raised (relative to the shut-off valve 3) and in the open position of the shutoff valve 3, the subvalvular cavity B communicates almost freely with the supravalvular cavity A through the longitudinal grooves 5 and the radial windows 4 of the shutoff valve 3 and through the longitudinal grooves 33 under ruzhinennogo valve 28.

 The throttle 30 is made adjustable, and its working tip 31 is made in the form of a return cone, and the Central hole 29 of the spring-loaded valve 28 has a cylindrical shape. Such design features of the hydraulic lock 27 provide an increase in its manufacturability, cost reduction and easy adjustment of the size of the said throttle gap, which in turn allows lowering loads of various weights in the optimal speed mode. The piston stroke 8 is equal to the maximum displacement of the piston 8 minus the axial clearance between the piston rod 9 and the first control piston 6 and the axial clearance between the piston rod 7 and the shutoff valve 3. In other words, the stroke of the piston 8 determines the lift of the shutoff valve 3 with the spring loaded valve 28 (when applying control pressure to chamber D). Similarly, the magnitude of the stroke of the piston 6, equal to its maximum displacement minus the axial clearance between the stem 7 and the shut-off valve 3, determines the lift of this valve with a spring-loaded valve 28 when the control pressure is applied to chamber B.

 Nadklapannaya cavity And is connected to the piston cavity of the actuating cylinder 34, with the help of which the lifting and lowering of the carriage 35 are carried out both with the load 36, and idle. The pump 37 through the on-off valve 38 communicates with the sub-valve cavity B, and through the reversible valve 39 with the control cameras B and D. Safety valve 40 is necessary to protect the pump 37 from overloads. By-pass valve 43 is connected to control chambers B and D through check valves 41 and 42. The setting pressure of the specified valve, which serves to reduce power consumption when lowering the loaded cylinder 34, is significantly less than the setting pressure of the safety valve 40.

 The area of the first control piston 6 of the hydraulic lock 27 is determined from the condition that it is impossible to open the shutoff valve 3 if there is a working pressure in the supravalve cavity A from the weight of the carriage 35 with the load 36. On the other hand, the area of the piston 6 should be sufficient to open the shutoff valve 3 and hold it in this position, if there is a slight pressure in the supravalve cavity A from the weight of the empty carriage 35. The piston stroke 6 is assigned from the condition that the shut-off valve 3 is raised by such a value that the lower end of the central hole The hole 29 is located significantly higher than the lower end of the working tip 31 of the throttle 30. In this case, with an increase in the working stroke of the piston 6, the radial clearance between the working tip 31 and the central hole 29 will increase (by 1-2 orders of magnitude compared to the size of this gap when the shut-off valve 3 is in initial lower position), which leads to a sharp decrease in throttle properties of the specified gap and, accordingly, the possibility of lowering the cylinder 34 idle for the minimum possible time.

 The area of the second control piston 8 is larger than the area of the first control piston 6, since it is assigned from the condition of guaranteed opening of the shut-off valve 3 if the valve has a working pressure from the weight of the carriage 35 with a load of 36. The stroke of the piston 8 is assigned less than the stroke of the piston 6, since the movement of the piston 8 should not lead to any significant increase in the radial clearance. In this case, the throttle properties of the specified gap are preserved, which eliminates the possibility of the carriage 35 falling with the load 36 within the stroke of the cylinder 34 during the lowering operation.

 In FIG. 3 shows an embodiment of the proposed hydraulic lock, in which the working tip of the throttle 30 is made in the form of a stepped cylinder 44, and the Central hole 29 of the spring-loaded valve 28 has a conical shape. The diameter of the cylindrical tip 44 is larger than the diameter of the throttle shank 30.

 The proposed hydraulic lock works as follows. In the initial state, the distributors 20, 21 and the elements of the hydraulic locks 1, 13 occupy positions, as shown in FIG. 1. Cylinders 16, 17 with carriages 18, 19 are in the lower position. When the distributor 20 is switched to the left position, the oil from the pump 22 enters the subvalve cavity B of the hydraulic lock 1, moving its shutoff valve 3 upwards and compressing the weak spring 12. From the subvalve cavity B, the oil passes through the longitudinal grooves 5 and the radial windows 4 of the shutoff valve 3, the supravalve cavity and the check valve 14 is fed into the working cavity of the cylinder 16, thereby lifting the carriage 18. The pressure developed by the pump 22 in this operation is determined mainly by the payload on the cylinder 16 from the weight of the loaded carriage 18. Odnrovr Menno oil from the pump 22 is supplied to the working pressure in the first chamber B control hydraulic lock 13 and the first control piston 6 with piston rod 7 of the hydraulic lock are moved upward by raising the shutoff valve 3 and thereby informing the working cavity of the cylinder 17 to the tank. During this period of time, the cylinder 17 remains stationary, as it is in the lower position. The carriage 18 is stopped by switching the distributor 20 to the initial middle position. To lower the carriage 18, the distributor 21 switches to the left position and the oil from the pump 22 enters the second control chamber D of the hydraulic lock 1. Under the pressure developed by the pump 22, the second control piston 8 with the rod 9 and, accordingly, the first control piston 6 with the rod 7 move upward, opening the shut-off valve 3 and communicating the working cavity of the cylinder 16 through the throttle 14, the over-valve cavity A, the radial windows 4, the longitudinal grooves 5, the under-valve cavity B and the distributor 20 with the tank. The cylinder 16 with the carriage 18 moves downward at a speed determined by the weight of the carriage 18 and the area of the working slit of the throttle 14. The excess capacity of the pump 22 through the valve 26 is poured into the tank.

 In the process of lowering the carriage 18, the carriage 19 does not move upward, since in this operation (when the distributor 21 is in the left position), the pump 22 is connected only with the chamber D of the hydraulic lock 1. In this case, the power consumption is minimal, since the pressure developed by the pump 22 in the process lowering and determined by the pressure settings of the valve 26, significantly less than the working pressure when lifting a particular carriage.

 At the end of lowering the carriage 18, the distributor 21 is moved to the middle position and the pressure in the chamber E of the hydraulic lock 1 is reduced. The control pistons 6 and 8, the rods 7 and 9 and the shutoff valve 3 under the action of their springs 10, 11 and 12 are returned to their original lower position. The hydraulic lock 1 closes.

 The operation of the hydraulic lock 13 when raising and lowering the carriage 19 is carried out in a similar manner. In this case, the valves 20 and 21 alternately switch to the right position.

 During operation, a situation may occur when, when the carriage 19 is in the upper position, the operator switches the distributor 20 to the left position (the distributor 21 is in the initial middle position). In this case, the oil from the pump 22 under the working pressure enters simultaneously into the cylinder 16 (through the hydraulic lock 1), lifting the carriage 18, and into the first control chamber B to the hydraulic lock 13. Under the action of the working pressure in the said chamber, the first control piston 6 with a rod 7 moves upward by raising the shutoff valve 3 and connecting the cylinder 17 to the tank. The cylinder 17 with the carriage 19 is lowered at a speed determined by the weight of the carriage 19 and the area of the working slit of the throttle 15. Therefore, the rise of the carriage 18 with the simultaneous lowering of the carriage 19 makes it impossible to simultaneously find both carriages in the upper position, which eliminates the possibility of their collision. This eliminates the need for a control electrical system with limit switches.

 Thus, equipping the hydraulic system of the lifting mechanism with the proposed hydraulic lock allows you to increase the reliability of this mechanism, because otherwise (when using known hydraulic locks and a control electrical system), a malfunction of the electrical system and erroneous operator actions make it possible to lift one carriage while the other carriage is in the upper position, which will cause a collision of the carriages. With the exclusion from the composition of the lifting mechanism of the control electrical system, its mass-dimensional parameters are reduced.

 It should also be noted that the use of the proposed hydraulic lock provides an increase in the reliability of the lifting mechanism with a minimum number of hydraulic locks (2 hydraulic locks) with a minimum number of shut-off valves (2 shut-off valves) and with minimal energy consumption during lowering the carriages. The energy consumption when lowering the carriage is significantly less than the cost of power when lifting it.

 The work of the proposed hydraulic lock containing a spring-loaded valve 28 and a throttle 30 with a working tip 31 (see Fig. 2), when lowering the carriage 35 with the load 36 is as follows. In the initial state, the distributors 38, 39 and all elements of the hydraulic lock occupy a position, as shown in FIG. 2. The pressure in the supravalve cavity A is equal to the operating pressure corresponding to the weight of the load 36 and the carriage 35. When the distributor 39 is switched to the right position, the oil from the pump 37 enters the second control chamber D of the hydraulic lock. Under the action of the pressure developed by the pump 37, the second control piston 8 with the rod 9 moves upward by the size of its stroke, thereby lifting the first control piston 6, the rod 7 and the shut-off valve 3 with the spring-loaded valve 28. The piston cavity of the cylinder 34 through undervalve cavity A, annular gap (throttle gap) between the central hole 29 and the working tip 31 of the throttle 30, radial windows 32 and 4, grooves 5, the undervalve cavity B and the distributor 38 are connected to the tank. The loaded cylinder 34 moves down at a nominal (optimal) speed, determined by the weight of the carriage 35 with the load 36 and the area of the throttle gap. The pressure developed by the pump 37 during lowering is determined by the setting pressure of the valve 43. The excess capacity of the pump 37 through the valve 43 is poured into the tank. After moving the valve 39 to the middle position, the pressure in the chamber D decreases. The control pistons 8 and 6, the rods 9 and 7, the shut-off valve 3 with the valve 28 under the action of both the working pressure in the supravalve cavity A and the springs 10, 11, 12 return to their original lower position. The hydraulic lock closes and the loaded cylinder 34 stops.

 If during the operation of lowering the loaded cylinder 34 there will be a violation of the integrity (destruction) of the line connecting the subvalvular cavity B to the distributor 38, then the speed of lowering the load 36 will remain almost unchanged. On the other hand, the destruction of such a line in a hydraulic system containing a known hydraulic lock prototype and a throttle installed in this line with a parallel shut-off distributor will cause a drop in the load within the stroke of the actuating cylinder. A drop in cargo will also occur in the event of pinching in the open position of the shutoff valve.

 Lowering the carriage 35 with the help of the proposed hydraulic lock (see Fig. 2) is done by switching the valve 39 to the left position. Oil from the pump 37 enters the first control chamber B, moving up the first control piston 6, rod 7 and shut-off valve 3 with valve 28. Since the stroke of the piston 6 is greater than the stroke of the piston 8, the lift of valve 28 in this operation is greater than the lift when lowering the loaded cylinder 34. In this case, the valve 28, upon completion of the piston 6 of its stroke, occupies a position in which the lower end of its central hole 29 is located above the lower end of the tip 31, as a result of which the radial clearance between the central m hole 29 and tip 31 increases. The cylinder 34, under the action of the weight of the empty carriage 35, moves downward, forcing the oil out of its piston cavity through the supravalve cavity A, the indicated radial clearance, radial windows 32 and 4, grooves 5, the subvalve cavity B and the distributor 38 into the tank. The presence of a small pressure drop on the hydraulic lock 27 and the distributor 38 eliminates the lowering of the cylinder 34 idle at an unacceptably high speed. The pressure developed by the pump 37 is determined by the setting pressure of the bypass valve 43. The specified pressure is sufficient to hold the piston 6 in the raised position in this operation. After switching the valve 39 to the middle position, the pressure in the chamber B decreases. The piston 6, the stem 7 and the shut-off valve 3 with the valve 28 are returned to their original lower position. The hydraulic lock closes and the cylinder 34 with the empty carriage 35 stops.

 If before lowering the carriage 35 with the load 36, the distributor 39 will be switched to the left position due to erroneous actions of the operator, the hydraulic lock 27 will not open, since the lifting force of the piston 6 (equal to the product of its area by the setting pressure of the valve 43) is not enough to overcome the clamping force of the shut-off valve 3 to its saddle (the specified pressing force is equal to the product of the saddle area and the working pressure in the supravalve cavity A and cylinder 34 and the weight of the carriage 35 with the load 36). This eliminates the possibility of the flow of oil from the loaded cylinder 34 into the tank without significant throttling and, accordingly, excludes the possibility of the fall of the carriage 35 with the load 36 within the stroke of the cylinder 34.

 Thus, the use of the proposed hydraulic lock in lifting hydraulic systems in comparison with the known hydraulic lock allows to increase the reliability of hydraulic systems when lowering goods by eliminating the possibility of their fall.

 As a numerical example, we consider the operating conditions of the proposed device and determine its parameters.

Initial data:
Working pressure in the supravalvular cavity A of the weight of the carriage 35 with a load of 36 (p) 10 MPa
Pressure in the supravalvular cavity A of the weight of the carriage 35 (p ₀ ) 1.5 MPa
Pressure setting valve 43 (p _CL ) 5 MPa
Seat Diameter of Shutoff Valve 3 (D _c ) 30 mm
Seat area of the shut-off valve 3 (S _c ) 7.07 • 10 ² mm ²
Outside diameter of shutoff valve 3 (D _s.cl. ) 50 mm
The area of the shut-off valve 3 (S _s.cl. ) 1.96 • 10 ³ mm ²
The diameter of the Central hole 29 (d _C.O. ) 15 mm
The area of the Central hole 29 (S _ts.o. ) _1,77 • 10 ² mm ²
Pressure in the drain lines None
The force of the springs 10, 11 and 12, the friction forces in the hydraulic lock, as well as the weight of its moving elements due to their smallness, are neglected.

где S $\genfrac{}{}{0ex}{}{\text{min}}{\text{2}}$ нижнее предельное значение площади второго управляющего поршня 8.The opening of the shut-off valve 3 for lowering the carriage 35 with the load 36 when applying pressure to the second control chamber D is provided if the condition is met
p _C. • S ₂ > p • S _c ,
where from

where s $\genfrac{}{}{0ex}{}{\text{<figure-callout id="2" label="min" filenames="00000009.png" state="{{state}}">min</figure-callout>}}{\text{2}}$ lower limit value of the area of the second control piston 8.

Из двух значений S $\genfrac{}{}{0ex}{}{\text{min}}{\text{2}}$ выбираем наибольшее.Since the value of S ₂ must be sufficient to hold the shut-off valve 3 in the open position during the lowering of the carriage 35 with the load 36, it is also necessary to meet the condition
p _C. • S ₂ > p • (S _s.cl.- S _t.s.o. ),
where from

Of the two values of S $\genfrac{}{}{0ex}{}{\text{min}}{}$$\genfrac{}{}{0ex}{}{}{\text{2}}$ choose the largest.

Открытие запорного клапана 3 и возможность падения каретки 35 с грузом 36 при подаче давления в первую управляющую камеру В исключаются, если выполняется условие
p_кл.•S₁ <p•(S_c),
откуда

где S $\genfrac{}{}{0ex}{}{\text{max}}{\text{1}}$ верхнее предельное значение площади первого управляющего поршня 6.Accepting S ₂ 3.85 • 10 ³ mm ² , determine the diameter D _{2 of the} second control piston 8

Opening the shut-off valve 3 and the possibility of the carriage 35 falling with the load 36 when pressure is applied to the first control chamber B are excluded if the condition
p _C. • S ₁ <p • (S _c ),
where from

where s $\genfrac{}{}{0ex}{}{\text{max}}{\text{one}}$ the upper limit value of the area of the first control piston 6.

где S $\genfrac{}{}{0ex}{}{\text{min}}{\text{1}}$ нижнее предельное значение площади первого управляющего поршня 6.On the other hand, to open the shut-off valve 3 when lowering the carriage 35 idle, the ratio
p _C. • S ₁ > p ₀ • S _c ,
where from

where s $\genfrac{}{}{0ex}{}{\text{min}}{\text{one}}$ lower limit value of the area of the first control piston 6.

Из двух значений S $\genfrac{}{}{0ex}{}{\text{min}}{\text{1}}$ выбираем наибольшее.Since the value of S ₁ must be sufficient to hold the valve 3 in the open position while lowering the carriage 35 idle, it is also necessary to withstand the condition
p _C. • S ₁ > p ₀ • (S _s.cl.- S _t.s.o. ),
where from

Of the two values of S $\genfrac{}{}{0ex}{}{\text{min}}{\text{one}}$ choose the largest.

The value of S ₁ must be within
5.34 • 10 ² mm ² <S ₁ <1.41 • 10 ³ mm ² .

Таким образом, при соблюдении требований приведенного расчета обеспечиваются как опускание груженой и ненагруженной каретки 35 при нормальных условиях, так и исключение возможности падения груженой каретки 35 при ошибочных действиях оператора (т.е. при подаче давления в первую управляющую камеру В).Accepting S ₁ 12.55 • 10 ² mm ² , determine the diameter D _{1 of the} first control piston 6

Thus, subject to the requirements of the above calculation, both the lowering of the loaded and unloaded carriage 35 under normal conditions, and the elimination of the possibility of falling of the loaded carriage 35 under erroneous actions of the operator (i.e., when applying pressure to the first control chamber B) are ensured.

 The magnitude of the radial clearance (throttle gap) between the Central hole 29 and the largest diameter of the working tip 31 is calculated based on the conditions for lowering the carriage 35 with the load 36 with a nominal speed. In this case, the relative position of the central hole 29 and the working tip 31 when the adjustable throttle 30 and valve 28 are in the lowest position is set so that during the lifting of valve 28 by the stroke of piston 8, the specified gap remains unchanged, which eliminates the possibility of lowering loaded carriages 35 with a speed greater than the nominal value.

 Since the working stroke of the piston 6 is assigned more than the working stroke of the piston 8, the magnitude of the radial clearance when lifting the valve 28 with the piston 6 increases significantly and the throttling effect of this clearance is reduced, which eliminates the lowering of the carriage 35 idling at an unacceptably low speed. Setting the required lowering speed of the carriage 35 idle (equal to the nominal value or slightly more) can be done by adjusting the position of the throttle 30 relative to the valve 28, raised by the stroke of the piston 6.

 The carriage 35 is lifted when the distributor 38 is switched to the right position. Under the pressure generated by the pump 37, the shut-off valve 3 is moved upward relative to the housing 2 and the spring-loaded valve 28 relative to the shut-off valve 3. The oil consumption of the pump 37 through the under-valve cavity B, grooves 5 and radial windows 4 of the shut-off valve 3, grooves 33 of the valve 28 and nadklapanny cavity And almost freely enters the cylinder 34, lifting the carriage 35. The pressure drop across the hydraulic lock 27 in this operation is small and is determined only by the compression force of the non-force spring 12 and the friction forces in moving electric Menten hydraulic lock. When the distributor 38 returns to its original position, the pressure in the subvalvular cavity B decreases, the hydraulic lock 27 closes and the carriage 35 stops.

 Thus, due to the features of the execution of the hydraulic lock, the invention provides an increase in the reliability of hydraulic systems with hydraulic locks, as well as a decrease in their overall dimensions.

Claims (4)

 1. A hydraulic lock comprising a housing, a shutoff valve forming a supravalve and subvalve cavity in the housing, and a first control piston interacting through the stem with a shutoff valve and forming a first control chamber with the housing, characterized in that the shutoff valve is coaxial to the last in the shutoff valve from the side of the supravalve cavity a spring-loaded valve with a central hole is installed, and an adjustable throttle with a working tip installed in said hole with a radial clearance communicating the over-valve is installed in the housing and subvalvular cavity at the open position of the valve.  2. The hydraulic lock according to claim 1, characterized in that the second control piston is installed in the housing from the side of the first control chamber, interacting through the second rod with the first control piston and forms a second control boat with the housing, while the second control piston has a stroke less than the stroke of the first control piston, and the area of the second control piston is larger than the area of the first control piston.  3. The hydraulic lock according to claim 1, characterized in that the working tip of the throttle is made in the form of a return cone, and the Central hole of the spring-loaded valve has a cylindrical shape.  4. The hydraulic lock according to claim 1, characterized in that the working tip of the throttle is made in the form of a stepped cylinder, and the Central hole of the spring-loaded valve has a conical shape.

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