RU2560216C1 - Hydropneumatic suspension of transport facility - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: proposed suspension comprises differential hydraulic cylinder, hydropneumatic accumulators, three-line proportional hydroelectric pressure control valve and electronic computing device. Said accumulators are connected to chambers of differential hydraulic cylinder. Outlet of three-line pressure control line is connected to hydraulic inlet of four-line pressure control valve while hydraulic line is connected to hydraulic system pressure line. Computing device inputs are connected with electric outputs of pressure transducers inside differential hydraulic cylinder. Widths of working openings of four-line valve sleeve are interrelated as working areas of the piston of said differential hydraulic cylinder. Overlaps of slide pair in four-line pressure control valve are negative.

EFFECT: enhance operating performances of wheel suspension.

4 cl, 5 dwg

Description

The vehicle wheel suspension (TS) is designed to perform many functions, the main of which is the provision of normalized vibration load of the cabin and the body with the crew, cargo and structural elements of the car. This task is reduced to ensuring the optimal frequency dependence between the amplitude of the vibration profile of the road and the amplitude of the vibration of the sprung mass. Such a frequency dependence is determined, first of all, by the natural vibration frequency of the sprung mass (moving the sprung mass up and down) per one wheel suspension, as well as by the vibration damping coefficient.

Vibration loading is regulated by ISO 2631-78 and GOST 12.1.012-90 standards. Vibration standards are set so that on the roads for which the car is designed, the vibrations of the driver and passengers do not cause them discomfort and fatigue, and the vibrations of the loads and structural elements of the car do not lead to damage. For example, in the frequency range of 4-8 Hz, the sensitivity of the human body to vibration increases, and the norms of vibration stress in this frequency range are tightened.

Another important function of the wheel suspension is the ability to change the amount of clearance of the sprung mass (clearance between the sprung mass and the road). The increase in clearance allows you to overcome the protruding macro-roughness of the road without contact of the sprung mass with the road surface, that is, it significantly increases the parameters of the vehicle cross-country ability. Reducing clearance allows the vehicle to move on roads with height restrictions and facilitates loading and unloading.

In addition, controlling the amount of clearance without stopping the vehicle can provide a number of other wheel suspension functions related to driving safety. For example, with the curvilinear movement of the vehicle, it becomes possible to increase the clearance of the suspension of the wheel located on the outer radius and reduce the clearance of the wheel located on the inner radius, and thereby reduce the risk of tipping the vehicle.

Vehicle suspensions are known for stabilizing the clearance of a sprung mass or providing a decrease in the amplitude of oscillations of a sprung mass (see BN Belousov, SD Popov, “Wheeled Vehicles of Extra Heavy Load”, Moscow, MGTU im, N.E. Bauman, 2006; p. 531, Fig. 13.12; p. 532, Fig. 13.13; p. 537, Fig. 13.18; p. 540, Fig. 13.19).

The well-known "Active air-hydraulic suspension of a vehicle" (Patent SU 901087, B60G 25/00, publication date 01/30/1982). The technical solution is aimed at improving reliability. For this purpose, the piston cavity of the cylinder is connected to the direct-flow pneumatic chamber through one pair of distributor nozzles, and a pressure and suction line of the pump are connected to another pair of nozzles of the distributor, in parallel with which a non-return valve is installed for the fluid to pass from the suction to the pressure line.

Common disadvantages of the known solutions is their low reliability.

The air-hydraulic active suspension with an executive pump is known (see VD Sharapov, “Active Suspension of Vehicles”, Riga Higher Military-Political Red Banner School named after Marshal of the Soviet Union SS Biryuzov SS, Riga, 1980, p. 54) which includes a differential hydraulic cylinder connecting sprung and unsprung masses; pneumohydraulic accumulators connected to the cavities of the differential hydraulic cylinder; proportional four-line electro-hydraulic distributor, the hydraulic input of which is connected to the discharge line of the hydraulic system, and the outputs to the cavities of the differential hydraulic cylinder; an electronic computing device, the inputs of which are connected to the electrical outputs of the pressure sensors in the cavities of the differential hydraulic cylinder; other hydraulic, electrical and electro-hydraulic devices. Such a suspension makes it possible to change the clearance and reduces the amplitude of oscillations of the sprung mass. However, the disadvantage of this suspension is the lack of an integrated approach to solving the problem of fulfilling both functions assigned to the suspension. This leads to a deterioration in the performance of the suspension: to increase the vibration load of the crew, cargo and structural elements of the car, to limit the ability to overcome the protruding irregularities of the road surface and road sections with height restrictions, reduce traffic safety. Based on the set of essential features, this decision was taken as a prototype.

The present invention is directed to a comprehensive solution to the problem, ensuring the performance of both functions assigned to the suspension, resulting in the following operating modes:

- automatic provision of a given clearance of a sprung mass without changing its own oscillation frequency;

- automatic provision of a given natural frequency of oscillations of the sprung mass at a constant value of the clearance of the sprung mass;

- simultaneous automatic provision of the set natural frequency of oscillations and clearance of the sprung mass.

The technical result when using the invention is to improve the performance of the vehicle’s wheel suspension and, as a result, increase the safety of transporting people and goods.

The technical result is achieved due to the fact that:

- the suspension further comprises a three-line electro-hydraulic distributor, the output of which is connected to the hydraulic input of the four-line proportional electro-hydraulic distributor, and the hydraulic input to the discharge line of the hydraulic system;

- a pneumohydraulic accumulator and a pressure sensor with an electrical output are connected to the hydraulic input of the four-line proportional electro-hydraulic distributor;

- the ratio of the widths of the working windows of the liner of the four-linear proportional electro-hydraulic distributor is equal, respectively, to the ratio of the values of the working areas of the piston of the differential hydraulic cylinder;

- the spool valve overlap of the four-linear proportional electro-hydraulic distributor is negative, and their absolute value is greater than the absolute value of the spool displacement from the middle position, which provides pressure values in the piston and rod cavities of the differential hydraulic cylinder, compensating for the static load proportional to the maximum sprung mass.

- the inputs of the electronic computing device are also connected to an electrical input to which a control signal for the clearance of the sprung mass is received; with an electrical input to which a control signal of the natural frequency of the unsprung mass is supplied; with the electrical output of the sensor for measuring the displacement of the housing of the differential hydraulic cylinder relative to its piston; with electrical outputs of gas temperature sensors in the pneumatic parts of pneumohydraulic accumulators connected to the cavities of a differential hydraulic cylinder.

- the first output of the electronic computing device is connected to the electrical input of a three-line two-position electro-hydraulic distributor that controls the position of one-way hydraulic locks that block hydraulic lines connecting the proportional four-line electro-hydraulic distributor to the cavities of the differential hydraulic cylinder and pneumohydraulic accumulators and adjustable chokes connected to them;

- the second output of the electronic computing device is connected to the first input of the adder, the second input of which is connected to the electrical output of the pressure sensor at the input of the four-line proportional electro-hydraulic distributor, and the output of the adder is connected to the electrical input of the three-line proportional electro-hydraulic distributor.

The invention is illustrated by drawings.

In FIG. 1 is a functional diagram of the inventive hydropneumatic suspension of a vehicle wheel.

In FIG. 2 is a functional diagram of hydraulic channels connecting the input and output of a four-linear proportional electro-hydraulic distributor with the cavities of a differential hydraulic cylinder for the middle position of the spool relative to the sleeve.

In FIG. 3 shows a scan of the sleeve of a four-linear proportional electro-hydraulic distributor.

In FIG. 4a, 4b, 4c shows the position of the spool of a four-linear proportional electro-hydraulic distributor for various operating modes:

- in FIG. 4a - with an increase in clearance of the sprung mass;

- in FIG. 4b - with a decrease in clearance of the sprung mass;

- in FIG. 4c - in the steady state of the differential hydraulic cylinder housing relative to its piston.

In FIG. Figure 5 shows the dependence of the forces acting on the housing from the piston and rod cavities of the differential hydraulic cylinder on the position of the spool of a four-linear proportional electro-hydraulic distributor (with a rigidly fixed housing of the hydraulic cylinder relative to its piston).

Pneumohydraulic suspension of a vehicle’s wheel contains: adders 1 and 2, electronic computing device 3, electric power amplifiers 4 and 5, three-line proportional electro-hydraulic distributor 6, four-line proportional electro-hydraulic distributor 7, pneumohydraulic accumulators 8, 10 and 13; pressure sensors with electric output 9, 12 and 15; temperature sensors with electric output 11 and 14, adjustable hydraulic chokes 16 and 17, three-line two-position electro-hydraulic distributor 18, one-way hydraulic locks 19 and 20, housing 22 and piston with rod 23 of the hydraulic differential cylinder 21, sprung mass 25, unsprung mass 26, wheel 27, a displacement sensor 24, a hydraulic discharge line 28, a hydraulic discharge line 29; inter-unit hydraulic lines 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, sleeve 48 and spool 49. four-way proportional electro-hydraulic distributor 7 .

The suspension of the wheel 27 when changing the clearance of the sprung mass 25 works as follows.

In the initial position, the difference of the signals (Uupr CL - Uoc1) does not go beyond the limited tolerance. The spool 49 of the electro-hydraulic distributor 7 is in the position shown in FIG. 4c. The hydraulic distributor 18 is in the "floor. one". Hydraulic locks 19 and 20 are closed. The control cavities of the hydraulic locks 19 and 20 are connected to the drain line 29 through hydraulic lines 36, 37 and 33, a hydraulic distributor 18, hydraulic lines 32, 31. The hydraulic lines 38 and 43, 41 and 42 are disconnected. At the entrance 3 ”of electronic computing device 3, a signal Uspr is supplied proportional to the natural frequency of the sprung mass 25. The electro-hydraulic distributor 6 is in the middle position. The hydraulic line 40 is disconnected from the hydraulic line 39 connected to the discharge line 28. A pressure is established in the pneumatic-hydraulic accumulator 8 and at the inlet of the electro-hydraulic distributor 6, providing pressure in the piston cavity of the differential hydraulic cylinder 21, in the pneumatic part of the pneumatic-hydraulic accumulator 10, in hydraulic lines 42, 44 46 pressure, which, together with the pressure set in the rod cavity of the differential hydraulic cylinder 21, in the pneumatic part of the pneumohydraulic accumulator 13, in hydraulic lines 43, 45, 47, provides a given natural frequency of oscillation of the sprung mass 25 and the equality of the total force on the housing 22 of the hydraulic cylinder 21 to the load, proportional to the value of the sprung mass 25.

To change the clearance of the sprung mass 25, a signal Uupr CL is proportional to the displacement of the housing 22 of the hydraulic cylinder 21 and the sprung mass 25 rigidly connected with it relative to the piston 23 of the hydraulic cylinder 21 and the unsprung mass 26 rigidly connected with it (a signal proportional to the sprung clearance masses). Signal Upr CL goes to the input "input. 1 "electronic computing device 3 and the input" input. 1 ”adder 2.

If the difference between the signal Uupr kl and the signal U _oc1 is proportional to the movement of the housing 22 of the hydraulic cylinder 21 relative to its piston 23, which is supplied from the output of the sensor 24 to the input “in. 2 "electronic computing device 3 and the input" input. 2 "adder 2, goes beyond the limits established by the admission, with the output of" out. 1 "electronic computing device 3 on the winding of the electro-hydraulic distributor 18 receives a control command Uper.

Electro-hydraulic valve 18 from the position "floor. 1 "goes to the" floor. 2 ”, connecting the hydraulic line 33 through the hydraulic lines 32 and 31 to the discharge line 28. Through the hydraulic lines 36 and 37, pressure is supplied to the control cavities of the hydraulic locks 19 and 20. The hydraulic locks 19, 20 open, connecting the output“ out. 1 "electro-hydraulic distributor 7 through the hydraulic lines 41, 42 and 44, the throttle 16 and the hydraulic line 46, with the piston cavity of the hydraulic cylinder 21, and the output" output. 2 "electro-hydraulic distributor 7 through the hydraulic lines 38, 43 and 45, the throttle 17 and the hydraulic line 47 with the rod cavity of the hydraulic cylinder 21.

The signal (Uupr kl - Uoc1) from the output of the adder 2 enters, through a power amplifier 5, into the winding of the electro-hydraulic amplifier 7. The spool 49 of the electro-hydraulic distributor 7 is displaced relative to its sleeve 48 by a value proportional to the value of the signal (Uupr kl - Uoc1).

If this value is greater than zero (Fig. 4a, the displacement of the spool 49 relative to the sleeve 48 is positive), then the hydraulic line 41 is connected to the hydraulic line 40, the pressure of which is determined by the pressure in the accumulator 8, and the hydraulic line 38 to the hydraulic line 35 connected through a hydraulic line 31 with a drain line 29. The housing 22 of the hydraulic cylinder 21 and the sprung mass 25 begin to move relative to the piston 23 of the hydraulic cylinder 21 and the unsprung mass 26, the clearance of the sprung mass 25 increases.

If the signal value (Uupr CL - Uoc1) is less than zero (Fig. 46, the displacement of the spool 49 relative to the sleeve 48 is negative), then the hydraulic line 41 is connected to the hydraulic line 35, and the hydraulic line 38 is connected to the hydraulic line 40. Housing 22 of the hydraulic cylinder 21 and the sprung mass 25 begin to move relative to the piston 23 of the hydraulic cylinder 21 and the unsprung mass 26, the clearance of the sprung mass 25 decreases.

With any change in the clearance of the sprung mass 25, the signal Uoc1 at the electrical output of the sensor 24 changes in proportion to this movement. The signal magnitude modulus (Uupr CL - Uoc1) decreases and the spool 49 of the electro-hydraulic distributor 7 shifts toward the initial position (Fig. 4c). The signals Uadr kl and Uoc1 are summed up in the electronic computing device and, when the value (Uadr kl - Uoc1) falls within the limits established by the tolerance, the output “out. 1 "electronic computing device 3 resets control command Uper; electro-hydraulic amplifier 18 switches to the "floor. 1 ", connecting the control cavity of the hydraulic locks 19 and 20 through the hydraulic lines 36 and 37, 33, 32 and 31 with the drain line 29. The hydraulic locks 19 and 20 are closed, separating the hydraulic lines 41 and 42, 38 and 43. The clearance of the sprung mass corresponds the size of the control team

The automatic provision of the specified clearance of the sprung mass without changing its own oscillation frequency is ensured by the constancy of pressure in the piston and rod cavities of the hydraulic cylinder 21 when its body 22 moves relative to the rod 23 in any direction and at rest. This constancy can be maintained only if the ratio of the width of the working windows of the sleeve 48 of the electro-hydraulic distributor 7 and the ratio of the areas of the piston 23 on the side of the piston and rod cavities of the differential hydraulic cylinder 21, as well as with negative overlap of the spool pair of the electro-hydraulic distributor 7, whose value is greater than the absolute the displacement value of the spool 49 from the middle position, which provides pressure values in the piston and rod cavities differential th hydraulic cylinder 21, compensating the static load proportional to the maximum value of the sprung mass 25.

These circumstances are confirmed by the following considerations. To calculate the pressure in the cavities of the hydraulic cylinder 21, it is used, as applied to the circuit shown in FIG. 2, addiction

here: Q is the flow rate of the working fluid;

A _dr - throttle area;

Δp _dr - differential pressure on the throttle.

(see Nazemtsev A.S., Rybalchenko D.E., "Hydraulic Drives and Systems", Moscow, Forum, 2007, p. 122).

In the case under consideration, A _dr is the current value of the working window of the sleeve 48 of the electro-hydraulic distributor 7.

Due to the lack of practical influence on the calculation results, pressure losses are not taken into account:

- in adjustable chokes 16 and 17, because their working areas are incommensurably greater than the maximum area of the working window of the sleeve 48;

- in hydraulic locks 19 and 20, because the sizes of the areas of their windows are selected only by the criterion of minimum losses.

The pressure in the hydraulic lines 35 and 31 connected to the drain line 29 of the hydraulic system is not taken into account. the static pressure in the discharge lines in hydraulic systems is approximately two orders of magnitude lower than the pressure in the discharge line, and is ensured in the design of hydraulic systems.

With increasing clearance of the sprung mass, the spool 49 occupies the position shown in FIG. 4a.

The flow rate of the working fluid flowing into the piston cavity of the hydraulic cylinder 21 is:

the flow rate of the working fluid flowing from the rod cavity of the hydraulic cylinder 21 is:

here: p _I - pressure at the outlet of the distributor 6;

p _PP - pressure in the cavity of the piston hydraulic cylinder 21;

p _PN - the pressure in the cavity of the rod hydraulic cylinder 22;

x ₃ - the magnitude of the movement of the spool 49 relative to the sleeve 48;

ℓ _PP - the width of the working window of the sleeve 48, through which the working fluid flows (flows in Fig. 4b) into the piston cavity of the hydraulic cylinder 21;

ℓ _ПШ - the width of the working window of the sleeve 48, through which the working fluid flows (flows in Fig. 4b) from the rod cavity of the hydraulic cylinder 21;

ℓ _P - the amount of overlap of the spool pair of the electro-hydraulic distributor 7.

The steady speed of movement of the housing 22 of the hydraulic cylinder 21 relative to the piston 23 with a continuous flow of the working fluid is:

, или

, or

here: A _PP - piston area from the side of the piston cavity;

A _PN - piston area from the side of the rod cavity.

After substituting (1) and (2) in (3):

and after reductions and transformations:

уравнение, связывающее давления в поршневой и штоковой полостях гидравлического цилиндра, приобретает вид:After substitution in (4)

the equation connecting the pressure in the piston and rod cavities of the hydraulic cylinder takes the form:

With a decrease in clearance of the sprung mass 25, the spool 49 occupies the position shown in FIG. 4b, and the equation relating the pressure in the cavities of the hydraulic cylinder 21 takes the form:

The second equation, connecting the pressure in the cavities of the hydraulic cylinder 21, is determined by the value of the sprung mass 25 and in all cases considered is:

here m is the value of the sprung mass 25, reduced to the housing 22 of the hydraulic cylinder 21.

The solution of the system of equations (5), (7) allows you to determine the pressure in the cavities of the hydraulic cylinder 21 with increasing clearance of the sprung mass:

The solution of the system of equations (6), (7) allows you to determine the pressure in the cavities of the hydraulic cylinder 21 while reducing the clearance of the sprung mass:

, т.е. только в случае равенства отношения величин ширины рабочих окон гильзы четырехлинейного пропорционального электрогидравлического распределителя 7 отношению величин рабочих площадей поршня 23 дифференциального гидравлического цилиндра 21.From a consideration of the pairs of equations (8) and (10), (9) and (11), it follows that the pressure is equal in the cavities of the hydraulic cylinder 21 with increasing and decreasing clearance of unsprung mass (p _{PP ↑} = p _{PP ↓} , p _{PN ↑} = p _{PS ↓} ) is provided only if

, i.e. only in case of equality of the ratio of the widths of the working windows of the liner of the four-linear proportional electro-hydraulic distributor 7 to the ratio of the working areas of the piston 23 of the differential hydraulic cylinder 21.

When this condition is met, equations (8) and (10) take the form:

and equations (9) and (11):

The sum of the pressures in the cavities of the hydraulic cylinder will be:

In the absence of movement of the housing 22 of the hydraulic cylinder 21 relative to the piston 23, the spool 49 takes the position shown in FIG. 4c, the flow rate of the working fluid through the edges of "cr1" and "cr2" of the spool 51 are equal to each other, the flow rate of the working fluid through the edges of the spool "cr3" and "cr4" of the spool 49 are also equal to each other:

Here x _{Z K} is the displacement value of the spool 49 relative to the sleeve 48, providing pressure values in the piston and rod cavities of the differential hydraulic cylinder 21, compensating for the static load proportional to the maximum value of the sprung mass 25;

equations linking, with open hydraulic locks, the pressure in the cavities of the hydraulic cylinder:

and

The solution of the system of equations (7), (15), (16) allows you to determine the pressure in the cavities of the hydraulic cylinder 21 in the absence of movement of the housing 22 of the hydraulic cylinder 21 relative to the piston 23:

and their amount:

The coincidence of equations (12) and (17) with each other and the coincidence of equations (13) and (18) with each other indicate that with an increase or decrease in clearance of the sprung mass 25, as well as at a constant value, the pressure in the piston cavity of the hydraulic cylinder 21 and the pressure in its rod cavity (p _PP and p _PN ) remain unchanged.

The coincidence of equations (14) and (19) indicates that the sum of these pressures is equal to the pressure at the inlet of the electro-hydraulic distributor 7 (p _in ).

The fulfillment of equations (17), (18) and (19), which determine the regulated flow of the working fluid, is ensured only if the overlap of the spool pair (sleeve 48 and spool 49) of the electro-hydraulic distributor 7 is negative and the absolute value of these overlaps is greater than the absolute the displacement of the spool from the middle position, which provides pressure values in the piston and rod cavities of the hydraulic cylinder 21, compensating for the static load proportional to the maximum value trained mass 25.

These circumstances are illustrated in FIG. 4a, 4b, 4c and FIG. 5 (with a rigidly fixed housing 22 of the hydraulic cylinder 21 relative to its piston 23).

- статическая нагрузка, которая определяется максимальным значением (m^max) подрессоренной массы 25.In FIG. 5

- static load, which is determined by the maximum value (m ^max ) of the sprung mass 25.

(Фиг. 4б, Фиг. 5) давление в поршневой полости гидравлического цилиндра 21 практически равно давлению в линии слива 29 и уравнения (17), (18) и (19) недействительны из-за неопределенности величины или полного отсутствия поступления рабочей жидкости в поршневую полость гидравлического цилиндра со стороны гидравлического входа электрогидравлического распределителя 7.When the values of the movement of the spool 49 relative to the sleeve 48, which are in the range

(Fig. 4b, Fig. 5) the pressure in the piston cavity of the hydraulic cylinder 21 is almost equal to the pressure in the discharge line 29 and equations (17), (18) and (19) are invalid due to the uncertainty of the value or the complete absence of the flow of working fluid into the piston cavity of the hydraulic cylinder from the side of the hydraulic inlet of the electro-hydraulic distributor 7.

(Фиг. 5) уравнения (17), (18) и (19) выполняются.When the values of the movement of the valve 49, which are in the range -

(Fig. 5) equations (17), (18) and (19) are satisfied.

(Фиг. 4а, Фиг. 5) уравнения (17), (18) и (19) недействительны из-за неопределенности величины или полного отсутствия оттока рабочей жидкости из поршневой полости гидравлического цилиндра 21 в линию слива 29; давление в поршневой полости с увеличением значения перемещения золотника 49 нарастает и стремится к величине давления на входе электрогидравлического распределителя 7 (p_вх).When the values of the displacement of the spool 49 are in the range

(Fig. 4a, Fig. 5) equations (17), (18) and (19) are invalid due to the uncertainty of the value or the complete absence of outflow of the working fluid from the piston cavity of the hydraulic cylinder 21 to the discharge line 29; the pressure in the piston cavity increases with increasing displacement of the spool 49 and tends to the pressure at the inlet of the electro-hydraulic distributor 7 (p _in ).

Similar reasoning is valid for the rod cavity of the hydraulic cylinder 21.

.The fulfillment of equations (17), (18), (19) is provided only in the range -

.

Thus, when the ratio of the widths of the working windows of the liner of the four-linear proportional electro-hydraulic distributor is equal, respectively, to the ratio of the values of the working areas of the piston of the differential hydraulic cylinder; and with negative overlap of the spool pair of a four-linear proportional electro-hydraulic distributor, the absolute value of which is greater than the absolute value of the displacement of the spool from the middle position, which provides pressure values in the piston and rod cavities of the differential hydraulic cylinder, compensating for the maximum static load proportional to the unsprung mass; provided by:

- the pressure is constant in the cavities of the differential hydraulic cylinder and in the cavities of the pneumohydraulic accumulators connected to them when adjusting the clearance of the sprung mass of the vehicle suspension, the inlet pressure of the four-line proportional electro-hydraulic distributor in this case remains constant;

- equality of the sum of the pressures in the cavities of the differential hydraulic cylinder and in the cavities of the pneumatic-hydraulic accumulators connected to them to the pressure at the inlet of the four-line proportional electro-hydraulic distributor when adjusting the clearance of the sprung mass of the vehicle suspension;

All these properties allow you to adjust the suspension sprung mass of the suspension without changing its natural frequency of oscillations associated with the pressures in the cavities of the differential hydraulic cylinder and in the cavities of the pneumohydraulic accumulators connected to them, and, in turn, with the pressure at the inlet of the four-linear proportional electro-hydraulic distributor.

The suspension of the wheel 27, if it is necessary to maintain a given natural frequency of oscillation of the sprung mass 25, for example, with an increase or decrease in this mass or with a change in gas temperature in the pneumatic cavities of the pneumatic-hydraulic accumulators 10 and 13, works as follows.

The starting position in this case is the same as in the case of adjusting the clearance of the sprung mass 25.

With a change in the value of the sprung mass at the inputs of "input. 4 "and" in. 6 "electronic computing device 3 changes the signals Udd pp and Udd ps coming from the outputs of the pressure sensors 12 and 15. When the temperature of the gas in the cavities of the pneumohydraulic accumulators at the inputs of" input. 5 "and" in. 7 "electronic computing device 3 changes the signals U _{DT PP} and U _{DT PN} coming from the outputs of the temperature sensors 11 and 14.

The signals arriving, sequentially or simultaneously, from sensors 11, 12, 14, 15 and the control signal Upr are processed by the electronic computing device 3. The result of the processing is the magnitude of the signal Udav at the output “out. 2 "electronic computing device 3, proportional to the pressure at the inlet of the electro-hydraulic distributor 7 (p _I ), providing a given natural frequency of the sprung mass 25.

The signal Udav goes to the input "input. 1 ”of the adder 1 and is summed with the input from the output of the pressure sensor 9 to the input“ input. 2 ”of adder 1 by a signal Uoc2 proportional to the pressure at the inlet of the electro-hydraulic distributor 7. The difference of the signals Uav - Uoc2 through the power amplifier 4 is fed to the winding of the electro-hydraulic distributor 6.

If the value (Udav - Uoc2) is greater than zero, the output of the electro-hydraulic distributor 6 is connected via a hydraulic line 39 to a discharge line 28 and the working fluid begins to flow into the hydraulic accumulator 8 and, through the negative overlaps of the spool pair (sleeve 48 and spool 49) of the electro-hydraulic distributor 7, into hydraulic lines 38 and 41.

Simulta_PP+ p_PSh) associated with the inlet pressure of the electro-hydraulic distributor 7 (p_in), formula 19. If the difference between the sum (Udd pp + Udd psh) and generated by the electronic computing device 3 signal U_giving goes beyond the limits established by the admission, from the exit “out. 1 "electronic computing device 3 on the winding of the electro-hydraulic distributor 18 receives a control command Uper.

Electro-hydraulic valve 18 from the position "floor. 1 "goes to the" floor. 2 ", connecting the hydraulic line 33 through the hydraulic lines 32 and 31 with the discharge line 28. Through the hydraulic lines 36 and 37, the pressure is supplied to the control cavities of the hydraulic locks 19 and 20. The hydraulic locks open, connecting the output" output. 1 "electro-hydraulic distributor 7 through the hydraulic lines 41, 42 and 44, the throttle 16 and the hydraulic line 46 with the piston cavity of the hydraulic cylinder 21, and the output" output. 2 "electro-hydraulic distributor 7 through the hydraulic lines 38, 43 and 45, the throttle 17 and the hydraulic line 47 with the rod cavity of the hydraulic cylinder 21.

The working fluid from the exit "out. 1 "of the electro-hydraulic distributor 7 through the hydraulic lines 41 and 42 enters the accumulator 10 and, through the hydraulic line 44, the adjustable throttle 16 and the hydraulic line 46, into the piston cavity of the hydraulic cylinder 21. The working fluid from the outlet" out. 2 "of the electro-hydraulic distributor 7 through hydraulic lines 38 and 43 enters the accumulator 13 and, through the hydraulic line 45, an adjustable throttle 17 and a hydraulic line 47, into the rod cavity of the hydraulic cylinder 21.

The pressures in the piston and rod cavities of the hydraulic cylinder 21 (p _PP and p _PN ) increase, respectively, the sum of the signals coming from the outputs of the pressure sensors 12 and 15 (Udd pp + Udd ps) to the inputs “input. 4 "and" in. 6 "of the electronic computing device 3, and when the difference between the value of the signal Uav generated by the electronic computing device 3 and this sum falls within the limits established by the tolerance, the output is" output. 1 "electronic computing device 3 resets control command Uper; electro-hydraulic amplifier 18 switches to the "floor. 1 ", connecting the control cavity of the hydraulic locks 19 and 20 through the hydraulic lines 36 and 37, 33, 32 and 31 with the drain line 29. The hydraulic locks 19 and 20 are closed, separating the hydraulic lines 41 and 42, 38 and 43.

If the value (Udav - Uoc2) is less than zero, the output of the electro-hydraulic distributor 6 is connected via a hydraulic line 34 to the drain line 29 and the pressure of the working fluid p _in decreases.

If the sum (Udd dp + Udd dp) is greater than the signal Udav generated by the electronic computing device 3 by the amount of the established tolerance, from the output “out. 1 "electronic computing device 3 on the winding of the electro-hydraulic distributor 18 receives a control command Uper.

Electro-hydraulic valve 18 from the position "floor. 1 "goes to the" floor. 2 ", connecting the hydraulic line 33 through the hydraulic lines 32 and 31 with the discharge line 28. Through the hydraulic lines 36 and 37, the pressure is supplied to the control cavities of the hydraulic locks 19 and 20. The hydraulic locks open, connecting the output" output. 1 "electro-hydraulic distributor 7 through the hydraulic lines 41, 42 and 44, the throttle 16 and the hydraulic line 46 with the piston cavity of the hydraulic cylinder 21, and the output" output. 2 "electro-hydraulic distributor 7 through the hydraulic lines 38, 43 and 45, the throttle 17 and the hydraulic line 47 with the rod cavity of the hydraulic cylinder 21.

The working fluid from the cavities of the hydraulic cylinder 21 and the pneumohydraulic accumulators 10 and 13 through the negative overlap of the spool pair (sleeve 48 and spool 49) of the electro-hydraulic distributor 7, begins to flow into the hydraulic drain line 29.

The pressures in the piston and rod cavities of the hydraulic cylinder 21 (p _PP and p _PN ) decrease, respectively, the sum of the signals coming from the outputs of the pressure sensors 12 and 15 (Udd pp + Udd ps) to the inputs “input. 4 "and" in. 6 "of the electronic computing device, and when the difference between the value of the Udav signal generated by the electronic computing device 3 and this sum (Udd dp + Udd dp - Udav) falls within the limits established by the tolerance, the output is" output. 1 "electronic computing device 3 resets control command Uper; electro-hydraulic amplifier 18 switches to the "floor. 1 ", connecting the control cavity of the hydraulic locks 19 and 20 through the hydraulic lines 36 and 37, 33, 32 and 31 with the drain line 29. The hydraulic locks 19 and 20 are closed, separating the hydraulic lines 41 and 42, 38 and 43.

In both cases considered, the pressures installed at the inlet of the electro-hydraulic distributor 7 and, accordingly, in the cavities of the hydraulic cylinder provide the specified natural frequency of oscillations of the sprung mass 25, while the total force acting on the housing 22 of the hydraulic cylinder 21 remains unchanged (20).

The unambiguity of the relationship between the given natural frequency of oscillations of the sprung mass 25 and the pressure value (p _in ) at the input of the electro-hydraulic distributor 7 is confirmed by the following considerations.

It is known that the natural frequency of the oscillatory system is determined by the formula

Here: ν is the natural vibration frequency, in the case under consideration, of the sprung mass 25 of the suspension of the wheel 27;

k is the stiffness of the spring, in the present case, the hydraulic cylinder 21 with pneumohydraulic accumulators 10 and 13 connected to its cavities;

m is the sprung mass 25 of the suspension of the wheel 27, reduced to the housing of the hydraulic cylinder 21.

Since the natural vibration frequency of the sprung mass 25 is set initially (based on the need to ensure vibration protection of passengers, cargo and structural elements of the car), formula 21 is conveniently written as a proportional relationship between the stiffness of the hydraulic cylinder 21 (k) with pneumatic-hydraulic accumulators 10 and 13 connected to its cavities and sprung mass of 25:

Wherein

Here k _PP - the stiffness of the hydraulic cylinder 21 from the side of the piston cavity;

k _ПШ - rigidity of the hydraulic cylinder 21 from the side of the rod cavity.

In its turn:

и

and

Here: k _{PP hydr} - the rigidity of the working fluid reduced to the housing 22 of the hydraulic cylinder 21, which depends on the total volume of the working fluid (V _{PP W} ) in its piston cavity, in the hydraulic cavity of the pneumohydraulic accumulator 10 and in the hydraulic lines 42 and 44; k _{pp mon} - gas stiffness reduced to the housing 22 of the hydraulic cylinder 21, which depends on the volume of gas (V _{PP G} ) in the pneumatic cavity of the pneumohydraulic accumulator 10; k _{PSH hydr} - the rigidity of the working fluid reduced to the housing 22 of the hydraulic cylinder 21, which is determined by the total volume of the working fluid (V _{ПШ Ж} ) in its rod cavity, in the hydraulic cavity of the pneumohydraulic accumulator 13 and in the hydraulic lines 43 and 45; k _{PN Mon} - the rigidity of the gas reduced to the housing 22 of the hydraulic cylinder 21, which depends on the volume of gas (V _{PSH G} ) in the pneumatic cavity of the pneumohydraulic accumulator 13.

From the definition of stiffness:

Here: ΔF - increment of the load acting on the housing 22 of the hydraulic cylinder 21; Δx - increment of movement of the housing 22 relative to the piston 23
when the pressure in the rod cavity of the hydraulic

cylinder 21 equal to atmospheric.

Since ΔF _PP = Δp _PP · A _PP and

или

и, после подстановки в (23):It is known (see, for example, Nazemtsev A.S., Rybalchenko D.E., "Hydraulic Drives and Systems", Moscow, Forum, 2007, p. 19) that for a liquid

or

and, after substituting in (23):

Here: E is the bulk modulus of elasticity;

V ₀ is the initial volume.

), из которого следует, чтоTo determine the pneumatic stiffness, the Clapeyron equation (universal gas law

), from which it follows that

Here: p _{0 PP} - the initial charging pressure in the gas cavity of the pneumohydraulic accumulator 10; V _{0 PP} - the initial volume of gas in the gas cavity of the pneumohydraulic accumulator 10; T _{0 PP} - gas temperature when charging the pneumohydraulic accumulator 10.

Similarly, for the piston cavity of the hydraulic cylinder 21:

From a comparison of (24) with (25) and (26) with (27) it follows that at values of E = 1400 ... 1700 MPa (see Nazemtsev A.S., Rybalchenko D.E., "Hydraulic Drives and Systems", Moscow, Forum, 2007, p. 19) and the maximum values of static pressure (p _PP , p _PS ), which in total cannot exceed the pressure in the discharge line (21.0 MPa ... 28.0 MPa), the influence of hydraulic stiffness (k _{PP hydr} , k _{PS hydr} ) is insignificant and may not be taken into account in further discussions. If you want to improve the accuracy of the exhibition of the natural frequency of oscillations of the sprung mass 25, a correction can be introduced into the value of the pressure at the inlet of the electro-hydraulic distributor 7 calculated below.

Considering the above:

Substituting equations (17) and (18) in (28):

and after the transformations, a quadratic equation is obtained that uniquely relates the pressure at the inlet of the electro-hydraulic distributor 7 to the suspension stiffness and, accordingly, to the natural vibration frequency of the sprung mass 25.

Here:

;

;

;

;

.

.

We rewrite these formulas in the form:

;

;

;

;

;

;

;

;Where

;

;

;

;

;

;

;

;

.

;

;

.

The solution of equation (29) determines the pressure at the inlet of the electro-hydraulic distributor 7 (p _I ).

Thus, a given natural frequency of oscillations of the sprung mass of the vehicle suspension is realized by the following operations:

- in the electronic computing device 3 are introduced the constants for this type of suspension, the values: C _a1 , C _a2 , C _b1 , C _b2 , C _c1 , C _c2 , C _c3 ;

- to the input of the suspension, and then to the input of the electronic computing device 3 receives a control signal Uappr, proportional to the set natural frequency (ν);

- to the inputs of the electronic computing device 3 is received: to the input "input. 4 "signal Udd pp, proportional to the value of the static pressure in the piston cavity (p _PP ) of the hydraulic cylinder 21; at the entrance 6 "signal Udd psh proportional to the static pressure in the rod cavity (p _PN ) of the hydraulic cylinder 21; at the entrance 5 "signal Udt pp, proportional to the gas temperature in the pneumatic cavity of the pneumohydraulic accumulator 10 and to the input" input. 7 "signal Uдт пш proportional to the gas temperature in the pneumatic cavity of the pneumohydraulic accumulator 13;

- electronic computing device 3 calculates the value of "m" according to the formula:

;

;

- electronic computing device 3 calculates the value of "k" according to the formula (22);

- electronic computing device 3 calculates the value of "p _I " by solving the quadratic equation (29) and generates the output "output. 2 "control signal Uav proportional to the value of" p _I ".

If it is necessary to simultaneously change the clearance of unsprung mass 25 and exhibit its natural frequency of its oscillations (for example, when lifting the sprung mass 25 after changing its value), the suspension operates in accordance with the two modes of operation described above. Uper command at the output “out. 1 "electronic computing device 3 is reset only when both the value (Uadr q - Uoc1) and the value (Udd qn + Udd qw - Udav) fall within the limits established by the tolerances.

Claims (4)

1. Hydropneumatic suspension of a vehicle wheel, comprising a differential hydraulic cylinder, in which a piston with a rod is placed, connecting sprung and unsprung masses, pneumohydraulic accumulators connected to the cavities of the differential hydraulic cylinder, a four-line electro-hydraulic distributor, an electronic computing device, the inputs of which are connected to electrical outputs pressure sensors in the cavities of the differential hydraulic cylinder, exl which includes a three-line proportional electro-hydraulic distributor, the output of which is connected to the hydraulic input of the four-linear proportional electro-hydraulic distributor, and the hydraulic input - to the discharge line of the hydraulic system, while the ratio of the widths of the working windows of the liner of the four-linear proportional electro-hydraulic distributor is equal to the ratio of the values of the working areas of the differential piston hydraulic cylinder and spool overlap th pair of four-way proportional solenoid valves are made all negative. 2. Hydropneumatic suspension of a vehicle wheel according to claim 1, characterized in that a pneumohydraulic accumulator and a pressure sensor with electrical output are connected to the hydraulic input of the four-line proportional electro-hydraulic distributor. 3. Hydropneumatic suspension of a vehicle wheel according to claim 1, characterized in that the inputs of the electronic computing device are connected to an electrical input to which a control signal for the clearance value of the unsprung mass is supplied; with an electrical input to which a control signal of the natural frequency of the unsprung mass is supplied; with the electrical output of the sensor for measuring the displacement of the housing of the differential hydraulic cylinder relative to its piston; with electrical outputs of gas temperature sensors in the pneumatic parts of pneumohydraulic accumulators connected to the cavities of a differential hydraulic cylinder. 4. Hydropneumatic suspension of a vehicle wheel according to claim 1, characterized in that the first output of the electronic computing device is connected to the electrical input of a three-line two-position electro-hydraulic distributor that controls the position of one-way hydraulic locks.

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