FR2766445A1 - Oleopneumatic suspension apparatus for road or rail vehicles - Google Patents

Abstract

The oleopneumatic suspension apparatus has a first compression check valve (CL1,CL1), and expansion second check valve (CL2,CL2), a compression first hydraulic valve (V1,V1), an expansion second hydraulic valve (V2,V2), and a pre-loaded oleopneumatic accumulator (3,) constituted by a chamber. The apparatus also has a third check valve (CL3,CL3) and a hydraulic valve (V3,V3). The first of these third check valves (CL3) and hydraulic valves (V3) are mounted in parallel and are disposed between a certain point (A) and the chamber of the accumulator (A). The second set of these third check valves (CL3') and hydraulic valves (V3') are disposed between another point (A') and the chamber of the accumulator (A').

Description

OLEOPNEUMATIC DEVICE WITH LACING DAMPING AND
LONGITUDINAL
The present invention relates to oleopneumatic devices with yaw damping and longitudinal for road or rail vehicles.

 US Pat. No. 5,024,302 to KARNOP relates to a piloted damper capable of exhibiting a damping characteristic which can be controlled by means of electrically controlled valves.

 The accumulator here has the function of volume compensation and of ensuring a substantially constant pressure in the expanded chamber according to one or other of the non-return valves.

 The piloted shock absorber described in US patent S 024 302 does not have an anti-yaw stiffness function.

 The combination of two shock absorbers is not taught.

The company's certificate FR 2 252 228
AUTOMOTIVE PRODUCTS Ltd, relates to improvements in vehicle suspensions.

 As follows from this document, the aim of the device which is the subject of this document of the prior art is to produce a suspension for vehicles such that, when the dynamic load changes, resulting from a tendency to roll, when cornering, and a tendency to pitch due to a transfer of weight from the front to the rear during acceleration and deceleration, said suspension varies the quantity of liquid contained in cavities of liquid-filled frames, by which the weight of the vehicle is transmitted to the wheels, in order to keep the vehicle horizontal.

 This document of the prior art does not carry a damping of the lace and longitudinal object of the present invention.

 An analysis of the suspension for vehicles described in this document FR 2 252 228 is carried out at the beginning of the description.

 As results from this analysis, the vehicle suspension described in this document FR 2 252 228 clearly provides an anti-yaw return torque but has the major drawbacks below.

 The longitudinal stiffness and the lace stiffness are coupled due to the differential sections of the jacks.

 In fact, the longitudinal stiffness and the lace stiffness are determined by the precharge pressure of the accumulator.

 The flow restriction devices provide a damping function both when the upper chambers are compressed and expanded.

 In the event of very rapid relaxation, the upper chamber can cavitate.

It is therefore an object of the invention to design an oleopneumatic device with lace damping and a single longitudinal secondary suspension that does not have the drawbacks of known devices and incorporates the following functions:
- anti-yaw return torque with possibility of adjusting the anti-yaw stiffness without dismantling the oleopneumatic device with yaw and longitudinal damping,
- longitudinal damping, with the possibility of adjusting the viscance without dismantling the lace and longitudinal damping device,
- damping in laces with the possibility of adjustment without dismantling the device for damping the lace and longitudinal and with the possibility of increasing this damping without increasing the longitudinal damping.

 According to the invention, the oleopneumatic device with lace and longitudinal damping is as characterized in the claims.

 An advantage of the oleopneumatic device with lace and longitudinal damping of the invention is that it provides a stiffening anti-lace function.

Accumulators 3, 3 'identical preloaded induce a pneumatic stiffness which is expressed via the hydraulic circuit and the lever arm by a return torque in laces, ideally linear in the form:
Mpneum = -K (PO, VO, S, a) ac, the meaning of the variables being given at the end of the description.

 The absence of differential section (sot = 0) of the cylinders does not induce any longitudinal preload or stiffness for the device.

 The modification of the PO preload of the accumulators makes it possible to modify the value of Ka.

 Another advantage of the lace and longitudinal damping device of the invention is that it provides a longitudinal damping function.

The valves CL1 / V1, CL2 / V2 and
CL1 '/ V1', CL2 '/ V2' allow to adjust the longitudinal damping characteristic Famx, F'amx generated by the device.

 The valves can be passive elements having a progressive opening as a function of the pressure difference, or an element whose passage cross section is controlled by an external system.

 When the chamber 1 is compressed, the valve CL1 is closed, the valve V1 makes it possible to regulate the pressure drop from chamber 1 to point A.

 Chamber 2 being relaxed, valve CL2 is open and short-circuits valve V2, there is therefore a minimum pressure drop between point A 'and chamber 2.

 This operating mode is characteristic of the device and differentiates it from document FR 2 252 228.

 The operation is symmetrical when the chamber 2 is compressed.

 The use of relief valves avoids any risk of cavitation in the relaxed chambers.

 The device of the invention makes it possible to have a greater range of control of the damping characteristic.

The device of the invention allows independent adjustment in compression and expansion, pressure regulation is always exercised at the level of the compressed chamber
The valves avoid any problem related to the dynamics of the valves.

 Compared to conventional twin-tube damping, the valves and valves are adjusted without removing the piston.

 Another advantage of the lace and longitudinal damping device of the invention is that it provides a lace damping function.

The CL3 / V3 and CL3 '/ V3' valve assemblies allow the introduction of additional pressure drops PB-P3 'and PA-P3 linked to the angular speed of laces to generate a couple of damping laces
Mama.

 This lace-up damping does not induce any additional contribution on the longitudinal damping.

 This property is linked to the symmetry of the jacks, which differentiates the device of the invention from the device described in document FR 2 252 228.

 It is therefore possible to increase the damping of laces without modifying the longitudinal damping.

 Another advantage of the lace and longitudinal damping device of the invention is that it can be controlled.

 Valves V1, V2; V1 ', V2' and V3, V3 'can be passive components, for example valves having a progressive opening as a function of the differential pressure.

 These valves can also be controlled externally to control the passage section.

The orifices of the valves V1, V2 can, for example, correspond to the two passage sections of a 4/2 valve or to two 2/2 valves. the same applies to valves V1 ', V2' and V3, V3 '
The control of the passage sections of the orifices of the valves V1, V2 and V1 ', V2' makes it possible to control the longitudinal damping forces Famx, F'amx.

 The device of the invention therefore makes it possible to ensure semi-active control over the longitudinal and lace-up modes.

Longitudinal cushioning and lace cushioning can be completely decoupled.

 it is then a longitudinal damping and controlled laces, ensuring an angular stiffness in laces.

 The structure and the implementation of the device according to the invention therefore differ from the devices described in documents FR 2 252 228 and US 5 024 302 as follows from the description of the preferred embodiment.

 Other objects, characteristics and advantages of the invention will appear on reading the description of the preferred embodiment of the oleopneumatic device with lace and longitudinal damping, description made in conjunction with the drawings in which the single figure is a schematic representation of the lace and longitudinal damping device according to the invention.

 The description below relates to an analysis of the suspension for vehicles described in document FR 2 252 228.

Let Pa be the atmospheric pressure, it comes in terms of force for each cylinder
F = (P2-Pa) S2 - (P1-Pa) S1
= (P2-P3 ') S2 - (P1-P3) S1 + (P3'-Pa) S2 - (P3-Pa) S1
Likewise
F '= (P2'-P3) S2 - (P1'-P3') S1 + (P3-Pa) S2 - (P3'-Pa) S1
So
F = Famx + Fpneum and F '= F'amx + F'pneum
With
Famx = (P2-P3 ') S2 - (P1-P3) S1 Fpneum = (P3'-Pa) S2
(P3-Pa) S1
F'amx = (P2'-P3) S2 - (P1'-P3 ') S1
F'pneum = (P3-Pa) S2 - (P3'-Pa) S1
F and F 'including
- an amortization term (Famx, F'amx) linked to pressure drops in the circuit. These pressure drops are themselves related to the flow in the restrictions which are a function of the speed of actuation of the jacks, which justifies the term of damping force.

 - a term of pneumatic stiffness (Fpneum, F'pneumi linked to the variation of the pressures (P3'-P3) of the accumulators.

The pressure of the accumulators is a function of the internal gas volume of the accumulators. By translating the conservation of the volume of fluid in the hydraulic circuit, under the assumption of incompressibility of the oil in front of the gas, it is shown that this variation in volume is linked to the displacement of the pistons. The forces Fpneum and F'pneum are therefore a function of the displacement of the piston which justifies the term of pneumatic stiffness.

By noting St = S2 - S1
S = (S2 + S1) / 2
It comes for the body, in terms of longitudinal result (R) and moment in laces in O (Mo)
R = F + F '= (Famx + F'amx) + [(P3-Pa) + (P3'-Pa)] St
Mo = (F'-F) a = (F'amx - Famx) a + 2Sa (P3-P3 ')
We get depreciation terms
Ram = (Famx + F'amx)
MOam = (F'amx-Famx) a
Longitudinal stiffness term with preload
Rpneum = [(P3-PA) + (P3'-Pa)] St
Rpneum z 2 (PO-Pa) St - Kx (PO, VO, St) xc
The stiffness Kx depends on the preload and the volume and the differential section of the cylinders
A booster couple in laces Mpneum = 2Sa (P3-P3 ')
Mpneum -K (PO, VO, S, a) cxc
The angular stiffness S is a function of the preload and the volume of the accumulators (PO, VO), of the sum of the thrust sections (S) and of the lever arm (a). In the event of simultaneous displacement of the cylinders, the gas volume of the accumulators remains identical, therefore the pressures of the accumulators remain identical, there is no restoring torque. On the other hand, when the pistons move in the opposite direction (laces), there is a reduction in the volume of gas in one accumulator and an increase in the other, so a pressure difference is created between the accumulators which results in a torque reminder.

This system therefore clearly provides an anti-yaw return torque, however
- The accumulator is present as an element of elasticity to support the body (this function is real due to the asymmetry of the thrust sections of the jacks).

 - The use of the accumulator as angular stiffness in laces is suggested in the general text but is not claimed.

 - Emphasis is placed on the lace-up and longitudinal damping effects.

 - The differential sections of the cylinders couple the longitudinal stiffness and the angular stiffness in laces, in fact, these two stiffnesses are determined by the precharge pressure of the accumulator. It is a drawback of the system.

 The single figure represents a diagram of the principle of the lace damping device and longitudinal according to the invention.

 The oleopneumatic device with lace and longitudinal damping comprises a first Al and a second Al 'damper.

 Each shock absorber comprises a body 11, 11 'in which slides a piston 12, 12' full provided with a rod 13, 13 'the assembly constituting a jack 114, 114'.

 The rod 13, 13 'passes through the piston 12, 12' right through.

 The piston 12, 12 'delimits a first chamber 1, 1' said compression chamber and a second chamber 2, 2 'said expansion chamber.

 The body 12, 12 'is filled with a fluid 16, 16', for example hydraulic oil.

 The damper also includes a first non-return valve CL1, CL1 'said compression valve and a second non-return valve CL2, CL2' said expansion valve.

 A first hydraulic valve V2, V2 'said compression valve and a second hydraulic valve V1, V1' said expansion valve can be controlled electrically.

 The semi-active shock absorber also comprises a precharged oleopneumatic accumulator 3, 3 ′ consisting of a chamber.

 Such an oleopneumatic accumulator 3, 3 'forms a fixed volume comprising an inert gas under pressure and hydraulic oil to which the gas communicates its pressure.

 The two fluids are generally physically separated by a membrane or a bladder.

 The function of this accumulator consists, on the one hand, of absorbing the volume of oil corresponding to the volume of the rod when the damper is completely compressed and, on the other hand, of ensuring a minimum pressure in the hydraulic circuit.

 The compression valve CL1, CL1 'and the expansion valve V1, V1' are mounted in parallel.

 The compression valve CL1 and the expansion valve V1 are arranged between the expansion chamber 1 and an intermediate point A.

 The compression valve CL1 'and the expansion valve V1' are arranged between the expansion chamber 1 'and an intermediate point A'.

 The relief valve CL2, CL2 'and the compression valve V2, V2' are mounted in parallel.

 The expansion valve CL2 and the compression valve V2 are arranged between the compression chamber 2 and the intermediate point A '.

 The relief valve CL2 'and the compression valve V2 are arranged between the compression chamber 2' and the intermediate point A.

 A valve CL3, CL3 'and a valve V3, V3' are mounted in parallel.

 The valve CL3 and the valve V3 are arranged between the intermediate point A and the chamber of the accumulator 3.

 The valve CL3 'and the valve V3 are arranged between the intermediate point A' and the chamber of the accumulator 3 '.

 The orientation of the valves is as shown in the single figure.

 The jacks 114, 114 'are arranged longitudinally, preferably in the same plane, moreover, in the case of a railway application, between a bogie 14 of a railway vehicle and the body 15 of the vehicle.

 One end of the jacks 114, 114 'is secured to the bogie 14 of the rail vehicle and the other end of the jacks 114, 114' is secured to the body 15 of the vehicle.

 The description below relates to an analysis of the oleopneumatic device with lace damping and longitudinal in accordance with the invention which takes up the analysis of document FR 2 252 228 in the particular case where St = 0, S1 = S2 = S.

 The pressures are introduced at the intermediate points A and A '.

After calculation, it comes
F = [(P2-PB) - (P1-PA)] S + [(PB-P3 ') - (PA-P3)] S + (P3'-P3) S
F '= [(P2'-PA) - (P1'-PB)] S + [(PA-P3) + (PB-P3')] S + (P3
P3 ') S
We notice
Famx = [(P2-PB) - (P1-PA)] S
F'amx = [(P2'-PA) - (P1'-PB)] S
Fama = [(PA-P3) - (PB-P3 ')] S
So
R = F + F '= Famx + F'amx
Mo = (F'-F) a = (F'amx-F'amx) a + 2Famcxa + 2 (P3-P3 ') Sa
We obtain
- A pair of laces
Mpneum = 2 (P3-P3 ') Sa
Mpneum S (P0, V0, S, a) ac
The angular stiffness S is a function of the preload and the volume of the accumulators (PO, VO), of the sum of the thrust sections (S) and of the lever arm (a). In the event of simultaneous displacement of the cylinders, the gas volume of the accumulators remains identical, the pressures of the accumulators remain identical, there is no return torque. By cons when the pistons moves in the opposite direction (yaw), iya reduction in the volume of gas in one accumulator and increase in the other, so we create a pressure difference between the accumulators which results in a return torque.

- Longitudinal damping effort
Ram = Famx + F'amx
Famx and F'amx also induce a damping torque Mam = (F'amx-Famx) a
As shown by the expressions of Famx and F'amx as a function of pressure drops. These forces are determined by the valve / valve assemblies (CL1 / V1, CL2 / V2, CL1 '/ V1',
CL2 '/ V2')
- A damping couple in lace
Mamcx = 2 Famcca = 2 [(PA-P3) - (PB-P3 ')] Sa
This torque has no effect on the longitudinal damping. It is determined by the pressure drops (PA
P3) and (PB-P3 ') therefore by the flap / valve assemblies (CL3 / V3,
CL3 '/ V3').

PA-P3 is Wied at the fluid flow QA3 from A to the chamber of the accumulator 3. By translating the conservation of flow, it comes
QA3 = Sx-Sx'S (xc-aac) -S (xc + aac) = -2S a ac.

 Therefore PA-P3 is linked to ac, similarly PB-P3 'is linked to QB3' = 2S ac and therefore to cxc which justifies the interpretation of yaw damping.

List of variables used
F, F 'cylinder force on body (N), 1/2 distance between body attachment points of
cylinders (lever arm) (m), x, x 'longitudinal displacement of body / bogie at point
cylinder attachment (m), xc longitudinal displacement of the body at point O of the
body, fixed bogie (m) with box / bogie lace (rad), transverse movement of the body in the center of
gravity (m), crate lace (rad), x, x 'longitudinal displacement crate / bogie at point
cylinder attachment (m), xc longitudinal displacement of the body at point O of the
body, fixed bogie (m), body / bogie lace (rad),
S1 cylinder section rod side (asymmetrical cylinder) (m2),
S2 cylinder section bottom side (asymmetrical cylinder) (m2),
St difference in cylinder thrust section (m2),
St = S2 - S1 rod section if the cylinder is
asymmetrical (m2),
St = O if the cylinder is symmetrical,
S cylinder section (symmetrical cylinder) (m2),
S = (Sl + S2) / 2 if the cylinder is asymmetrical
V1, V2, V3, V3 ', V1', V2 'loss control device
load, with progressive opening depending on the
pressure (passive system), with controlled opening
externally (pilot system electrically by
example, (V1, V2) or (V3, V3 ') or (seen', V2 ') can
correspond to the two orifices of the same valve,
CL1, CL2, CL3, CL4 non-return valves,
PO, vO pressure and initial volume of accumulators 3 and 3 '
(suspension at rest),
V vehicle speed (direction of travel) (m / s).

Claims (5)

1. Oleopneumatic device with lace damping  and longitudinal, characterized by a first Al and a  second Al 'shock absorber, each shock absorber comprising:  - a body (11, 11 ') in which a piston slides  (12, 12 ') full fitted with a rod (13, 13') the whole  constituting a jack (114, 114 '), said rod (13,  13 ') passing through said piston (12, 12') right through  part, said piston (12, 12 ') defining a first  chamber (1, 1 ') and a second chamber (2, 2'), said  body (12, 12 ') being filled with a fluid (16, 16'),  - a first non-return valve CL1, CL1 ', a second  non-return valve CL2, CL2 ', a first valve  hydraulic V2, V2 'and a second hydraulic valve  V1, V1 ', an oleopneumatic accumulator (3, 3')  preloaded consisting of a chamber, said valve  compression CL1, CL1 'and said expansion valve V1,  V1 'being mounted in parallel, said valve  compression CL1 and said expansion valve V1 being  arranged between the expansion chamber (1) and a point  intermediate A, said compression valve CL1 'and  said expansion valve V1 'being arranged between  said expansion chamber (1 ') and a point  intermediate A ', said expansion valve CL2, CL2' and  said compression valve V2, V2 ′ being mounted in  parallel, said relief valve CL2 and said valve  compression V2 being arranged between the  compression (2) and said intermediate point A ', said  relief valve CL2 'and said compression valve  V2 'being arranged between the compression chamber  (21) and said intermediate point A,  - a valve CL3, CL3 'and a valve V3, V3' mounted in  parallel, said valve CL3 and said valve V3 being  disposed between said intermediate point A and said  accumulator chamber (3), said valve CL3 'and  said valve V3 'being disposed between said point  intermediate A 'and said accumulator chamber (3')  said cylinders (114, 114 ') being arranged  longitudinally between a vehicle bogie (14)  rail and the body (15) of the vehicle, one of the  ends of said cylinders (114, 114 ') being integral  said rail vehicle bogie (14) and the other  end of said cylinders (114, 114 ') being integral  of said vehicle body (15). 2. Device according to claim 1, in which one  at least of said hydraulic valves V1, V1 ', V2,  V2 ', V3, V3' are electrically controlled. 3. Railway vehicle comprising a device with  yaw and longitudinal damping according to one  any of claims 1 or 2. 4. Train composed of at least one rail vehicle  comprising a lace damping device and  longitudinal according to claim 3. 5. Road vehicle comprising a device  yaw and longitudinal damping according to one  any of claims 1 or 2.