EA025353B1 - Hydropneumatic vehicle wheel suspension - Google Patents

Abstract

The invention relates to hydropneumatic vehicle suspensions. The technical result is improved performance of a vehicle wheel suspension and, therefore, higher safety of people and goods transportation. The technical result is attained by provision of a hydropneumatic vehicle wheel suspension comprising a differential hydraulic cylinder (21) accommodating a piston (23) with a rod and connecting sprung weight (25) and non-sprung weight (26), the first (10) and the second (13) four-way electrohydraulic control valve (7), pneumohydraulic accumulators connected to the cavities of the differential hydraulic cylinder (21) and the four-way electrohydraulic control valve (7), an electronic computing device (3) having inputs connected to electric outputs of pressure sensors (9, 12, 15) in cavities of the differential hydraulic cylinder (21), further including a three-way proportional electrohydraulic control valve (6), the output of which is connected to the hydraulic input of the four-way proportional electrohydraulic control valve (7), and the hydraulic input is connected to the pressure line (28) of the hydraulic system, where in the ratio of passage areas of sleeve orifices in the four-way proportional electrohydraulic control valve (7) is equal to the ratio of working areas of the piston (23) of the differential hydraulic cylinder (21), and overlaps of the slide valve pair in the four-way proportional electrohydraulic control valve (7) are performed negative.

Description

The invention relates to the field of engineering, in particular to hydropneumatic suspensions of vehicles.

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 profile cross-country ability of the vehicle. 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 to reduce the clearance of the wheel located on the inner radius, and thereby reduce the risk of tipping the vehicle.

Known wheel suspensions TS, stabilizing the clearance of the sprung mass or providing a decrease in the amplitude of 1 oscillations of the sprung mass (see Belousov B.N., Popov S.D. Wheeled vehicles of especially heavy lifting capacity. - M .: Publishing house of MGTU named after 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 Active air-hydraulic suspension of a vehicle is known (patent 8I 901087, B60C25 / 00, publication date January 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.

Known pneumohydraulic active suspension with an executive pump (see Sharapov V.D. Active suspension of vehicles // Riga Higher Military-Political Red Banner School named after Marshal of the Soviet Union SS Biryuzov - 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 with a constant value of the clearance of the sprung mass;

simultaneous automatic provision of the set natural frequency of oscillations and clearance

- 1,025353 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 additionally contains 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-linear 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 to the ratio of the values of the working areas of the piston of the differential hydraulic cylinder;

the overlap of the spool pair of the four-linear proportional electro-hydraulic distributor is negative, and their absolute value 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 static load proportional to the maximum value of the 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 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;

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-4c show the positions 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).

The pneumatic-hydraulic suspension of the vehicle wheel comprises adders 1 and 2, an electronic computing device 3, electric power amplifiers 4 and 5, a three-line proportional electro-hydraulic distributor 6, a 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;

- 2 025353 interblock 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 of 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 (Iupr kl - Ios1) does not exceed the limits limited by the tolerance. The spool 49 of the electro-hydraulic distributor 7 is in the position shown in FIG. 4c. The hydraulic distributor 18 is in position 1. 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 input of input 3 of the electronic computing device 3, a signal is supplied, proportional to the value of 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, an IUPR signal is sent to the suspension input, 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 to it (the signal is proportional to the sprung clearance masses). The Iupr CL signal is input to input 1 of the electronic computing device 3 and to input 1 of the adder 2.

If the difference between the IUPR signal and the IOS1 signal, proportional to the movement of the housing 22 of the hydraulic cylinder 21 relative to its piston 23, which comes from the output of the sensor 24 to the input of input 2 of the electronic computing device 3 and to the input of input 2 of the adder 2, goes beyond the limits established by the tolerance , from the output of the output 1 of the electronic computing device 3 to the winding of the electro-hydraulic distributor 18 receives an Iper control command.

The electro-hydraulic distributor 18 moves from position 1 to position 2, connecting hydraulic line 33 through hydraulic lines 32 and 31 to discharge line 28. Through hydraulic lines 36 and 37, pressure is supplied to the control cavities of the hydraulic locks 19 and 20. Hydraulic locks 19 , 20 open by connecting the output 1 of the 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 of the output 2 of the electro-hydraulic distribution the divider 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 (Iupr kl - Ios1) from the output of the adder 2 enters, through a power amplifier 5, into the winding of the electro-hydraulic distributor 7. The spool 49 of the electro-hydraulic distributor 7 is shifted relative to its sleeve 48 by a value proportional to the signal size (Iupr kl-Ios1).

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 (Iupr kl - Ios1) is less than zero (Fig. 4b, 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 Ios1 at the electrical output of the sensor 24 changes in proportion to this movement. The signal magnitude module (Iupr klos Ios1) decreases and the spool 49 of the electro-hydraulic distributor 7 shifts toward the initial position (Fig. 4c). The signals Iupr kl and Ios1 are summed up in the electronic computing device and when the value (Ipr kl - Ios1) falls within the limits established by the tolerance, the Iper control command is reset to output 1 of the electronic computing device 3; electro-hydraulic amplifier 18 switches to position 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. Hydraulic

- 3 025353 locks 19 and 20 are closed, separating the hydraulic lines 41 and 42, 38 and 43. The clearance of the sprung mass corresponds to the size of the control command Iupr class.

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 from the piston and rod cavities of the differential hydraulic cylinder 21 are equal, as well as with negative overlap of the spool pair of the electro-hydraulic distributor 7, the value of which 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 in relation to the circuit shown in FIG. 2, the dependence <? - Ά '0, 00 where O is the flow rate of the working fluid;

And ^d p - throttle area;

- differential pressure across the throttle.

(see Nazemtsev A.S., Rybalchenko D.E. Hydraulic drives and systems. - Moscow: Forum, 2007, p. 122).

In this case, 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, the pressure losses in the regulated chokes 16 and 17 are not taken into account, since their working areas are incommensurably greater than the maximum area of the working window of the sleeve 48;

in hydraulic locks 19 and 20, as 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 (/ nsh ~ θ '^' ( ^L s ⁺ n) 'psh

4p psh (2) where p _I - pressure at the outlet of the distributor 6; r _PP - the pressure in the cavity of the piston hydraulic cylinder 21; p _PSh - 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;

^pp - the width of the working window of the sleeve 48, through which the working fluid flows (flows in Fig. 46) into the piston cavity of the hydraulic cylinder 21;

^psh - the width of the working window of the sleeve 48, through which the working fluid flows (flows in Fig. 46) from the rod cavity of the hydraulic cylinder 21;

^{n 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

- 4 025353 where App - the area of the piston from the side of the piston cavity; And _PN is the piston area from the side of the rod cavity. After substituting (1) and (2) in (3):

and after reductions and transformations

After substitution in (4)

the equation linking the pressure in the piston and rod cavities of the hydraulic cylinder takes the form Ri \ - Rpp - ^k 'Rpsh (5)

As clearance of sprung mass 25 decreases, spool 49 occupies the position shown in FIG. 46, and the equation relating the pressure in the cavities of the hydraulic cylinder 21 takes the form

Rpp - ^K '(Roch Rps) (6)

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 under consideration has the form

RPP '/ PL ⁼ RPSH' A _P W + ^t ~ 8 O where t 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 decreasing the clearance of the sprung mass

_to _ “PSH, · ^ι ηπ _ | Apts

From a consideration of the pairs of equations (8) and (10), (9) and (11) it follows that the equality of pressure in the cavities of the hydraulic cylinder 21 with increasing and decreasing clearance of unsprung mass (Rppt RpprRipip RpshR is provided only if ПП ^ П / P 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 satisfied, equations (8) and (10) take the form and equations (9) and (11)

- 5,025353

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

Rpp ⁺ Rpsh ⁼ Rvh (14)

In the absence of movement of the housing 22 of the hydraulic cylinder 21 relative to the piston 23, the spool 49 occupies the position shown in FIG. 4c, the flow rates of the working fluid through the edges kp1 and kp2 of the spool 51 are equal to each other, the flow rates of the working fluid through the edges kp3 and kp2 of the spool 49 are also equal to each other

0 \ ~ 0.6 · (( _n + x _zk ) '( _ns ' y / r _ns

0g - θ, 6 · (ί _n ~ KZK) + (nu '> / Pjn Rpsh ~ 0z - a, b + (x + c _{n sk)} · p and _{pp Rin} - p _claims 04 ~ ^x ~ sk θ'6Hp \ kp 'ppp a = C ₂ ; & = &;

Here x _3K 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;

the equations linking with open hydraulic pressure locks in the cavities of the hydraulic cylinder (A + X _ZK ) ~ · (p _bx ~ r _pn ) = {k ~ ^x s /, X 'RPP (1 ^ 1 and

(/? _p - x _{3 K} ) ² · (p _in - p _psh ) = (ί _p + x _ZK \ p _psh (16)

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) - (19), which determines 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 value of the spool displacement from mid-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 of Oren mass 25.

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

mouths

In FIG. 5 - static load, which is determined by the maximum value (t ^max ) of the sprung mass 25.

R:

. "_ /? Tah _ g-sh _ so, _ shch. , & - ^r pl ^{g r} psh ~ rpp ^l pp rpsh (20)

PSh

- 6 025353

When the values of the displacement of the spool 49 relative to the sleeve 48 are in the interval hz - −η (Fig. 4b, 5), the pressure in the piston cavity of the hydraulic cylinder 21 is almost equal to the pressure in the drain line 29 and equations (17) - (19) are invalid from due to the uncertainty of the magnitude or 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. When the displacement values of the spool 49 are in the interval ^{n 3 η} (Fig. 5), equations (17) - (19) are fulfilled <x <

nyayutsya. When the displacement values of the spool 49 are in the interval ⁿ ' ³ (Fig. 4A,

5), equations (17) - (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 with increasing value of the displacement of the spool 49 increases and tends to the pressure at the inlet of the electro-hydraulic distributor 7 (p _I ).

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

The fulfillment of equations (17) - (19) is provided only in the range ⁿ ' ^{3 i} .

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; a constant pressure is ensured 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 of 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.

When changing the magnitude of the sprung mass at the inputs and vh.4 vh.6 electronic computing device 3 changed Idd signals _PP and _PN Idd coming from the pressure sensors 12 and outputs 15. When changing the temperature of the gas in the cavities pneumatichydraulic batteries at the inputs Rin and vh.5 .7 electronic computing device 3 changes the signals Id _{T PP} and Id _{T 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 Ipr are processed by electronic computing device 3. The result of the processing is the value of the signal Going to the output 2 of the electronic computing device 3, proportional to the pressure at the input of the electro-hydraulic distributor 7 (rvh), providing a given natural frequency of the sprung mass 25.

The Idav signal arrives at input 1 of the adder 1 and is summed with the IOS2 signal input from input of the pressure sensor 9 to input 2 of the adder 1, proportional to the pressure at the input of the electro-hydraulic distributor 7. The difference between the Idav-Ios2 signals through the power amplifier 4 is fed to the winding electro-hydraulic distributor 6.

If the value (Idav-ios2) is greater than zero, the output of the electro-hydraulic distributor 6 is connected through the hydraulic line 39 to the 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.

Simultaneously, the electronic computing unit 3 computes the sum of the quantities Idd Idd _PP and _PN of signals arriving at its inputs the outputs from the pressure sensors 12 and 15. This amount sootvetst- 7 025 353 sum of pressure exists in the cavities of the hydraulic cylinder 21 (p + PFR _pn) associated with pressure at the inlet of electrohydraulic distributor 7 (p _Rin), the formula 19. If the difference between the sum (Idd Idd _nu + _nn) and formed electronic computing device 3 Idav signal goes beyond the set tolerance, the output of the electronic calculates chan.1 tion device 3 to the winding of the electro-hydraulic distributor 18 enters Iper control command.

The electro-hydraulic distributor 18 moves from position 1 to position 2, connecting hydraulic line 33 through hydraulic lines 32 and 31 to discharge line 28. Through hydraulic lines 36 and 37, pressure is supplied to the control cavities of the hydraulic locks 19 and 20. The hydraulic locks open connecting the output 1 of the 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 of the output 2 of the 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 output 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 output of the output 2 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 increase (p _pp and p _psh ), respectively, the sum of the signals coming from the outputs of the pressure sensors 12 and 15 (Ipd _pp + Idp _psh ) to the inputs of input 4 and input 6 of the electronic computing device increases accordingly 3, and when the difference between the value of the 11dav signal generated by the electronic computing device 3 and this sum falls within the limits established by the tolerance, the Iper control command is reset to output 1 of the electronic computing device 3; the electro-hydraulic amplifier 18 switches to position 1, connecting the control cavities 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 (Idav - Ios2) 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 _I decreases.

If the sum (Idd Idd _nu + _nn) over the formed electronic computing device 3 Idav signal by an amount specified tolerance, the output chan.1 electronic computing device 3 to the winding of the electro-hydraulic distributor 18 enters Iper control command.

The electro-hydraulic distributor 18 moves from position 1 to position 2, connecting hydraulic line 33 through hydraulic lines 32 and 31 to discharge line 28. Through hydraulic lines 36 and 37, pressure is supplied to the control cavities of the hydraulic locks 19 and 20. The hydraulic locks open connecting the output 1 of the 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 of the output 2 of the electro-hydraulic distributor 7 through hydraulic lines 38, 43 and 45, throttle 17 and 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 hydraulic cylinders 21 (p _{pm pn} and p) are reduced correspondingly reduced amount of signals from the pressure sensors 12 and 15 outputs (Idd Idd _nu + _nn) to the inputs and vh.4 vh.6 electronic computing device , and when the difference between the value of the Idav signal generated by the electronic computing device 3 and this sum (Idn _pp + Idn _psh - Idav) falls within the limits established by the tolerance, the Iper control command is reset to output 1 of the electronic computing device 3; the electro-hydraulic amplifier 18 switches to position 1, connecting the control cavities 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, respectively, 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 (pbx) 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 _1_

2π

(21) where ν is the natural vibration frequency, in the case under consideration, of the sprung mass 25 of the wheel suspension 27;

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

t - 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 pneumohydraulic accumulators 10 and 13 connected to its cavities and sprung mass 25

Wherein

where to _PP - the stiffness of the hydraulic cylinder 21 from the side of the piston cavity; to _PN - the rigidity of the hydraulic cylinder 21 from the side of the rod cavity.

In its turn

where to _{PP hydr} is 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 (U _{PP Zh} ) in its piston cavity, in the hydraulic cavity of the pneumohydraulic accumulator 10 and in the hydraulic lines 42 and 44;

to _{PP Mon} - gas hardness reduced to the housing 22 of the hydraulic cylinder 21, which depends on the volume of gas (At _{PP G} ) in the pneumatic cavity of the pneumohydraulic accumulator 10;

KPSh 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 (U _{ПШ Ж} ) in its rod cavity, in the hydraulic cavity of the pneumohydraulic accumulator 13 and in the hydraulic lines 43 and 45;

to _{PN PN} - gas stiffness reduced to the housing 22 of the hydraulic cylinder 21, which depends on the gas volume (U _{PSH G} ) in the pneumatic cavity of the pneumohydraulic accumulator 13.

From the definition of stiffness

Ah, where ΔΤ is the increment of the load acting on the housing 22 of the hydraulic cylinder 21;

Dx is the increment of displacement of the housing 22 relative to the piston 23 when the pressure in the rod cavity of the hydraulic cylinder 21 is equal to atmospheric.

As

It is known (see, for example, Nazemtsev A.S., Rybalchenko D.E. Hydraulic drives and systems. M: Forum, 2007, p. 19) that for liquid or

X ₌ £ ae “e ₀

- 9 025353 and after substituting in (23) for _g

EL PP (24)

PP hydr.

'OPP W where E is the bulk modulus of elasticity;

At ₀ is the initial volume.

To determine the pneumatic stiffness, the Clapeyron equation (universal

RU .

gas law = SOP81), from which it follows that, after substituting in (23)

where p ₀ pp is the initial charging pressure in the gas cavity of the pneumohydraulic accumulator 10; At _{about PP} - the initial volume of gas in the gas cavity of the pneumohydraulic accumulator 10;

That pp is the 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. - M.: Forum, 2007, p. 19) and the maximum values of static pressure (p _pp , p _psh ), which in total cannot exceed the pressure in the discharge line (21.0-28.0 MPa), the influence of hydraulic stiffness (k _{pp hydr} , to _{psh hydr} ) is insignificant and in further considerations may not be taken into account. 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.

taking into account the above

substituting equations (17) and (18) in (28)

and after the transformation, 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.

^a 'RU + b-p _ex + s-0 (29)

- 10 025353 where

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:

constants, for a given type of suspension, SIZES S., 1 are introduced into the electronic computing device 3. ^C ^ C ^ ^{C L2, C} ch ^{C2, C3;} to the input of the suspension, and then to the input of the electronic computing device 3 receives a control signal IUPR mid, proportional to the set natural frequency (ν);

the inputs of the electronic computing device 3 receive: input 4 input signal Id _PP , proportional to the static pressure in the piston cavity (p _PP ) of the hydraulic cylinder 21; input 6 input IDH _PN proportional to the static pressure in the rod cavity (p _PN ) of the hydraulic cylinder 21; input 5 input signal Id _{T PP} , proportional to the temperature of the gas in the pneumatic cavity of the pneumohydraulic accumulator 10 and input input 7 signal and Cmd _PN , proportional to the temperature of the gas in the pneumatic cavity of the pneumohydraulic accumulator 13;

electronic computing device 3 calculates the value of m according to the formula _ Rln '^ nn ~ Rnn' ^ nl.

// I>

§ electronic computing device 3 calculates the value of k by the formula (22); electronic computing device 3 calculates the value of p _I by solving the quadratic equation (29) and generates an Idav control signal proportional to p at the output o.2.

r _vh .

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 described above

- 11 025353 works. The Iper command at the output 1 of the electronic computing device 3 is reset only when both the value (Ipr kl - Io1) and the value (Idn _pn + Iod _P w - Idav) fall within the limits established by the tolerances.

Claims (4)

1. Hydro-pneumatic suspension of a vehicle wheel comprising a differential hydraulic cylinder (21) in which a piston (23) is located with a rod connecting the sprung (25) and unsprung (26) masses, the first (10) and second (13) four-line electro-hydraulic a distributor (7), pneumohydraulic accumulators connected to the cavities of a differential hydraulic cylinder (21) and a four-line electro-hydraulic distributor (7), an electronic computing device (3), the inputs of which are connected to an electric electrical outputs of pressure sensors (9, 12, 15) in the cavities of the differential hydraulic cylinder (21), characterized in that it further includes a three-line proportional electro-hydraulic distributor (6), the output of which is connected to the hydraulic input of the four-line proportional electro-hydraulic distributor (7), and the hydraulic the input is to the discharge line (28) of the hydraulic system, and the ratio of the area of the passage section of the working windows of the liner of the four-linear proportional electric ogidravlicheskogo distributor (7) is the ratio of the quantities of working areas of the piston (23) of a differential hydraulic cylinder (21) and a pair of four-way slide valve overlap proportional electrohydraulic distributor (7) are negative. 2. Hydropneumatic suspension of a vehicle wheel according to claim 1, characterized in that a third pneumohydraulic accumulator (8) and a pressure sensor (9) 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 (3) are connected to an electrical input to which a control signal for the clearance value of the unsprung mass (26) is received; with an electrical input to which a control signal of the natural frequency of oscillation of the unsprung mass arrives (26); with the electrical output of the displacement measuring sensor of the housing (22) of the differential hydraulic cylinder (21) relative to its piston (23); with electrical outputs of gas temperature sensors (11, 14) 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 (3) is connected to the electrical input of a three-line on-off electro-hydraulic distributor (6) that controls the position of one-way hydraulic locks (19, 20). - 12 025353 □ α = π □ α □. _{ί (} , Ra Ρ '. Ρδτ Ρ- Rsl - 13 025353 FIG. 4c