DE9001053U1 - Hydropneumatic suspension - Google Patents

Description

Registered letter to Uwe Beinhauer

German Patent Office Am Seeberg 12a

Zweibrückenstrasse 12 6380 Bad Homburg

8000 Munich 2 26.01.1990

Hydropneanatic suspension

Various systems of hydraulic suspensions are known in which gas cushions alone or together with other suspension elements provide the suspension of the vehicle. The present invention is based on the state of the art of vehicle suspensions that use gas cushions together with hydraulic systems to transfer the driving force and pressure, so-called hydropneumatic suspensions (source: Reinpzell, Jörnsen, Fahrwerkstechnik: Radaufhängungen, Vogel-Verlag, Würzburg, 1988.)

This known ^type of vehicle suspension has considerable disadvantages. These consist in the fact that when the springs are operated repeatedly and violently within a short period of time, for example when driving fast on poor road surfaces, the gas is compressed several times within a short period of time, which leads to an increase in the temperature of the gas.

The increase in the temperature of the gas is also due to the fact that during the vibration damping of the suspension movement in the hydraulic system of the hydropneumatic suspension, kinetic energy is converted into heat, which causes the hydraulic oil to heat up. This prevents the dissipation of excess heat from the gas cushion through the hydraulic oil, since the amount of heat transferred is small when the temperature gradient is small; not to mention that the change in the viscosity of the hydraulic oil when the temperature increases worsens the vibration damping.

By heating the gas in the hydropneumatic suspension, its pressure is increased, causing the suspension to harden.

Since the volume of gas in the hydropneumatic suspension required to support the vehicle weight is too large to be effectively changed in the short period of time during the suspension process, it is very difficult to control the pressure of the gas in the

Hydropneumatic suspension can be adapted to requirements during suspension, e.g. by admitting compressed air.

1 To avoid the disadvantages of the above-mentioned state of the art,

I iiik the present invention has the task of developing a hydro-

\ pneumatic suspension to be designed in such a way that the impact caused by heavy work

% caused release of gas -:dc ¹⁴ -* hardening caused by it

j of the suspension is reduced, that excessive mention of the hydraulic

I lik-öls is reduced; and that it is possible to reduce the pressure of the gas

4 to change quickly.

I The task is solved by dividing the volume of the Gar.^s

&rgr; is divided into a high-pressure gas chamber (13) and a low-pressure gas chamber (9),

[ which is provided with an additional membrane (12) which is connected to a

1 provided Menfaran support (11) against the low-pressure gas chamber (9)

% are separated from each other.

t When the vehicle compresses, a piston (4) in a ¹ spring strut

;' Base body (1) is moved upwards. Hydraulic oil (6) is pumped from the front

5 lumen of a piston rod (4c). The piston rod (4c) is in the

P Hollow inside and partly filled with a cooling liquid (5), e.g. water with

&igr;; an antifreeze. By moving the KoI-

■| bens (4) with the piston rod (4c) during the spring, the cooling

: liquid (5) is spun up and down inside the piston rod (4c)

I dert, whereby in the upper part of the piston rod (4c) it absorbs heat from the hydraulic oil (6) via its wall and in the lower part of the KoI-

■ piston rod (4c), which is in the airstream, transfers this heat to the airstream via the wall ''- of the piston rod (4c).

■ The hydraulic oil (6) displaced by the piston rod (4c) is

\ a pressure stage shock absorber valve (7) is pressed against a separating membrane (8) and presses this against the gas cushion in the low-pressure gas chamber (9). If the pressure of the gas in the low-pressure gas chamber (9) reaches the same value as the pressure of the gas in the high-pressure gas chamber (13), the gas in the low-pressure gas chamber (9) presses the additional membranes (12) away from the membrane support (11) against the gas in the high-pressure gas chamber (13), so that the latter is also compressed and the volumes of the low-pressure gas chamber (9) and the high-pressure gas chamber (13) act as a spring element. This is particularly evident in Figure 3.

The diaphragm support (11) is convex at the edge and towards the inner wall of a cover (14) of the pressure chamber (13) and has a concave depression (11b) in the middle towards the inner wall of the cover (14). The membrane support (11) has openings (11a) over its entire surface. The gas in the low-pressure gas chamber (9) can flow through these openings (11a) against the additional membrane (12) and push it away from the membrane support (11) when the pressure increases accordingly, as shown in Figure 3. The shape of the membrane support (11) means that the additional membrane (12) is initially lifted off the membrane support (11) in the area of the concave depression (11b) when the pressure increases accordingly, as shown in Figure 3. Figure 12a in Figure 3 shows. As the pressure increases further, the additional membrane (12) is lifted further and further away from the membrane support (11) towards the edge, as Figure 12b in Figure 3 shows.

If the vehicle bounces again, the gas in the high-pressure gas chamber (13) and in the low-pressure gas chamber (9) expands again until the additional membrane (12) is pressed against the membrane support (11) by the gas in the high-pressure gas chamber (13). When the additional membrane (12) is in contact with the membrane support (11), the gas in the high-pressure gas chamber (13) cannot expand any further, so that from then on only the gas in the low-pressure gas chamber (9) can expand further. In this way, the pressure difference between the high-pressure gas chamber (13) and the low-pressure gas chamber (9) is maintained in the cool state and under light loads.

When the gas expands, the separating membrane (8) is pressed downwards against the hydraulic oil (6), which pushes the hydraulic oil through the compression shock absorber valve (7) against the piston (4). The piston is then pressed downwards into its initial position, ^and the hydraulic oil (6) located between the piston (4) and the base (3) of the spring element flows through the rebound shock absorber valves (4b) in the piston (4).

A connection for additional hydraulic lines (1a) enables the connection of other hydraulic components, such as pressure oil pumps, or the combination of several spring elements to form a common spring system.

duction in which the pressure in the BDchdruck-Gasraisn (13)

is to be varied during the journey, as shown in Figure 4, a flow control valve (20) is used in place of a high-pressure gas filling valve (14a) in the cover (14) of the high-pressure gas chamber (13). A compressed air line (21), which leads to a compressor (21a) or to a compressed air tank, and a drain line (22) are connected to this flow control valve (20).

An acceleration sensor (15) is attached to the piston rod (4c) or to another part of the chassis and is connected to a computer (17) by means of a measuring cable (16). This computer (17) has additional connections (18) via which, if required,

The computer (17) controls the flow control valve (20) in the cover (14) of the pressure gas chamber (13) by means of a fixed or variable program via a control cable (19), which can increase the pressure in the high-pressure gas chamber (13) by opening the compressed air line (21) and reduce it again by opening the pressure relief line (22).

The advantages achieved are that

- at high loads, the volume of the working gas cushion is increased by the volume of the high-pressure gas chamber (13), which reduces the increase in the temperature of the gas at high loads and thus the resulting hardening of the suspension,

- during the springing, the cooling liquid (5) inside the hollow piston rod (4c) removes heat from the hydraulic oil (6) and releases it into the airstream, whereby the temperature load on the hydropneumatic suspension is reduced by the heat generated during shock absorption,

- by reducing the volume to be changed to that of the high-pressure gas space (13), the gas cushion of the hydropneumatic suspension reacts more quickly to changes in pressure, so that the hydropneumatic suspension can be quickly adapted to different loads.

Several embodiments of the invention are possible. Four embodiments are shown in the drawings. They show:

Figure 1: Section through a spring element with gas chambers arranged at the top in the initial position

Figure 2: Exploded view of a spring element with gas chambers arranged at the top

Figure 3: Section through a spring element with gas chambers arranged at the top in gan2: compressed position, with functional positions of the additional meniljrans (12)

Figure 4: Spring element with gas chambers arranged at the top with electronically controlled regulation of the pressure in the high-pressure gas chamber (13)

Figure 5: Section through a spring element with laterally arranged gas chambers in initial position

Figure 6: Section through a spring element with spatially separated gas chambers in the initial position.

List of reference numbers

1 Spring strut base body 23 !!hydraulic connection 1a Connection for hydraulic additional line line

2 Screw plug 24 Hydraulic pot

3 Floor 25 Longitudinal axis

4 pistons

4a Piston ring 4b Rebound damper valve 4c Piston rod 4d Cap for filling coolant

5 Coolant

6 Hydraulic oil

7 compression damper valve

8 Separation membrane

9 Low pressure gas compartment

Low-pressure gas chamber wall 10a Low-pressure gas filling valve Diaphragm support 11a Openings 11b Trough Additional membrane

12a Functional position of the additional membrane at the beginning of the corresponding pressure increase 12b Functional position of the additional membrane with further pressure increase High-pressure gas chamber cover

14a High-pressure gas filling valve Acceleration sensor Measuring cable 16a Movable part of the measuring cable Computer Additional connections Control cable Flow control valve Compressed air line 21 α Compressor SKI =fi_T/->-;-»-.T^~

Claims (2)

Uwe Beinhauer ^ Am Seeberg 12a 'i[ 6380 Bad Hariburg 26.01.1990 Protection claims 1. Hydropneumatic suspension for vehicles, with a gas cushion and a hydraulic system working together with it, characterized by the following features: - A high-pressure gas chamber (13) is separated from a low-pressure gas chamber (9) by an additional membrane (12) which is supported on a membrane support (11) provided with openings (11a) against the low-pressure gas chamber (9) and rests against this membrane support (11) in the initial position. - A computer (17) is operatively connected to an acceleration sensor (15) and to a flow control valve (20), which in turn is connected by means of a compressed air line (21) to a compressor (21a) or a compressed air tank and to a discharge line (22), the computer (17) actuating the flow control valve (20) according to a fixed or variable program. 2. Hydropneumatic suspension for vehicles according to claim 1, characterized in that: - A piston rod (4c) is hollow and is partially filled with a cooling liquid (5) inside.