DE2251090A1 - PNEUMATIC, IN PARTICULAR HYDROPNEUMATIC SUSPENSION SYSTEM FOR MOTOR VEHICLES - Google Patents

Description

PATENT LAWYERS

DIPL .- (PHYS.) ING.H.VON SCHUMANN DIPL- (CHEM.) ING.W.D. OEDECOVEN

I UyO

Dresdner Bank AG Munich 8 Munich 22, Widenmayentraße S

Account No. 3 388 992 Telegram drette: Protector Munich

Pottery account: Munich 49463 Phone 0811-224893

18.10.1972 • 5 / ct

AEDIE-WEBK GMBH, Nuremberg, Sigmundstrasse 135,. IBIESEKE & HOEPMEE GMBH, Erlangen-Bruck

Pneumatic, especially hydro-pneumatic Suspension system for Eraftfanrzeuge

The invention relates to a method of manufacture equal pressures in the hydro-pneumatic or pneumatic spring elements or groups of a pendulum axle of Motor vehicles with hydraulic or pneumatic stabilization and separate hydraulic or pneumatic circuits controlled by their own control valves. It concerns as well a device for carrying out the method.

In the case of suspension systems of the type mentioned at the beginning with hydraulic or pneumatic stabilization by counter-cylinder or double-acting piston rod cylinder there is inevitably a separate one for each spring element Circle. Every connection between the circles would have the effect of stabilization because of the pressure equalization that would then be possible lift.

A level maintenance or control as usual by scanning the frame center distance on all four bathrooms or Eadgruppen of a motor vehicle for the respective associated hydraulic or pneumatic circuit results in uneven ground conditions no vehicle position. A at

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If the vehicle is stationary, e.g. a higher bathroom, would be on its own after the necessary built-in delay has expired "on rules". If the regulation takes place, the diagonally opposite bathroom will inevitably carry an increased load must, consequently einfedera and must give the same command to yourself, so that ultimately the vehicle on two to stand diagonally opposite baths. The other two bathrooms are more or less relieved, springy accordingly and give the command "Abregein" for themselves, with at least one of the two being completely relieved will. In the general case, the vehicle will lean to one side, whereupon this side in turn issues an up-regulation command, etc., until the energy stored in the main memory for the case of the stationary vehicle engine is used up by continued useless payment processes. The same process also takes place when the vehicle is moving with the difference that during the journey, due to the constant fluctuations in the load of the bath and the resulting changing spring suspension, it is not a complete, but only a partial one Pressure reduction in one and the diagonally opposite spring element comes.

For the reasons outlined above, one is forced to give the level maintenance or control the form of a three-point support, i.e. the arrangement of the level sensors in this way meet that two of the required four sail valves have a common scanning point, so that, for example, the level sensors are attached as far outside to the right and left as possible on an axis, so that the axis-parallel position from here and the level maintenance of the vehicle is determined at the other axis, however, the level maintenance is only scanned at one point in the middle of the axis, so that any lateral inclination of the vehicle on the level maintenance

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spring elements belonging to this axis has no influence. This gives the vehicle, similar to a farm tractor, one fixed axis and a pendulum axis.

The formation of an axis as a pendulum axis with level scanning in the center of the axis and separate pressure medium circuits for however, each bathroom group is only possible if it is provided for becomes that in the two pressure medium circuits the same pressures prevail * A connection of the two circuits is as at the beginning mentioned not possible because the stabilizer effect would be lost. A theoretically conceivable total sealing of the two circles without the risk of leaks also does not achieve the goal, since in addition to the accidental pressure differences present in the two spring elements at the moment of fixing, the temperature differences are also included their influence on the viscosity and volume of the quantities of oil introduced or discharged. These temperature differences can be caused, for example, by one-sided solar radiation. There must therefore be an additional Compensation to be created, as for a pendulum axle without individual level control required for each bath, the same or approximately the same pressure is produced in the spring elements of this axis.

According to the invention, this object is achieved in that, depending on the pressure ratio of the two hydraulic or Pneumatic circuits, the Begel valves for the two circuits are automatically adjusted against each other in such a way that when the suspension is actuated by adjusting the valve opening times against each other, a pressure equation for the two axes is achieved, whereupon the adjustment is reversed and the control valves work eynchronously.

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22b Ί 090

According to the invention, this method is implemented with a device, one resiliently in the smock position held double-acting piston-cylinder unit is provided, which, acted upon by the pressures of the two hydraulic and / or hydraulic. Eneumatic circuits, a link between one level sensor attached in the center of the axis and the two control valves adjusted so that the Begel valves in the sense of a pressure equalization of the two circles when actuating the suspension Open the circuit with the higher pressure when decelerating or open the circuit with the lower pressure when regulating up rather supply with the print medium. The connecting rod preferably has a two-armed lever, one of which free linde with the level sensor and its other free end via two pivotally connected to the end Rods are coupled to the control valves and the end of the piston rod of the piston-cylinder unit is the fulcrum of the two-armed lever forms, the arrangement of the rods is made so that in the middle position of the piston Linkage is aligned symmetrically to a center line and when the piston rests against one of the cylinder ends Control slide of the Hegel valves by a certain amount are offset from one another.

With the method or device according to the invention it is possible to use a hydraulic or hydro-pneumatic suspension, especially for trucks or buses to create that is hydraulically or pneumatically stabilized and a stable position of the motor vehicle in the state and guaranteed while driving by designing an axle as a pendulum axle.

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22b109Q

The following is an embodiment of the invention with reference to the accompanying schematic drawing, for example described. Show in it:

I "ig. 1 a circuit diagram of the pressure medium circuits for front and rear axle of a motor vehicle, with baths with the corresponding rocker arms are folded into the plane of the drawing}

]? ig. 2 the double-acting piston-cylinder unit and the connecting rods to the control valves for the case P ₁ > P ₂ i

3 shows the double-acting piston-cylinder unit and the connecting rods to the control valves for the case P ₁ ^ P ₂ ;

The embodiment of the invention according to FIG. 1 is a hydro-pneumatic suspension, the pressure medium from a main accumulator 13, for example with 200 atmospheres, which are applied by a pump 14 and monitored with the aid of an overflow valve 15, via check valves 16 is fed to the respective hydraulic circuits. In the main memory for the hydraulic fluid is such of a known type, wherein the hydraulic fluid is separated by a membrane of fluid under pressure ^v nitrogen. The pressure in the main accumulator can vary between 60 atmospheres of voltage and 200 atmospheres of operating pressure.

Each wheel 17 is connected to the suspension elements via rocker arms 18, which are fastened to the frame with their axis 19 20 connected. The suspension elements consist of a piston

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Cylinder unit, the cylinder space being connected to a pressure accumulator 21 via throttle openings or valve arrangements is. At the same time, the rocker arm is firmly connected to an opposing cylinder, the so-called stabilizer Cylinder space acted upon by the hydraulic circuit of the other bath will. The movement of the two baths is elastically coupled by the stabilizers, creating a rocking effect avoided vibrations around the longitudinal axis of the vehicle.

The part of FIG. 1 shown to the right of the main memory relates to the rear axle of a motor vehicle and is not part of the present invention. The part of FIG. 1 lying to the left of the main memory shows the hydraulic circuits the pendulum axis and is the subject of the invention.

Each of the separate hydraulic circuits 1, 2 is of one Begel valve 3 or 4 regulated with control spools 12. The control spools can be moved in a cylinder in such a way that that the hydraulic circuit in question either with the supply line from the main memory or the discharge line via a throttle valve 23 is connected to the pressureless reservoir 24. One in the derivative built-in valve assembly is also not the subject of the present invention. The control slide of the Begel valve e close in their middle position both inlet and outlet to the hydraulic circuits, so that the spring constant the spring elements remain the same in this * state.

As the load on the vehicle increases and the distance between the frame and the axle decreases, the Level sensor 7 via the connecting rod 6 the two control pistons 12 of the Begelvalves so that the hydraulic circuits are connected to the pressure medium at the same time, whereby

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the respective pressures are increased until the original distance between frame and axis is restored and the supply lines are closed again. With decreasing load on the vehicle through static or dynamic Loads are drawn by the level sensor 7 cLie control piston via the Linkage 6 from the middle position into a position where the hydraulic circuits are connected to the drain and the pressure in the hydraulic circuits drops until the original distance between frame and axle is restored is. In this state, the control piston has closed the discharge line and supply line again.

The described mode of operation assumes that the pressures in hydraulic circuit 1 and 2, P, - and Pp are the same. Since no separate level control is provided for each wheel, the same spring characteristics are used for the left and Right front wheel is only available if the pressures in the respective hydraulic circuits are the same. As a result of inevitable Leakages in the piston-cylinder units, bztj »as a result of different Regulated quantities and temperature differences can, however, be pressure differences between the two circles not completely prevent it. In order to reduce these pressure differences as quickly as possible, the connecting rod 6 a double-acting piston-cylinder unit 5 is connected, which is held in the central position by a spring. The end the piston rod of this unit displaces a two-armed lever 8 from its symmetrical position depending on the pressure ratio between P ^. and P2 so that the connecting rods 9 get different effective lengths to the control spools of the control valves, with the result that the control valves no longer work synchronously, but with a certain temporal shift.

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For example, if P ^ is greater than P2 »will Set a state according to Fig. 2, i.e. the piston 11 of the piston-cylinder unit 5, will lie against the right cylinder wall, and the connecting rod 6 to the right move, whereby the connecting rod 9 to the cone valve 3 opposite the connecting rod 9 to the Hegel valve 4-relative shortened. The consequence of this is that in the event of a curtailment, circuit 1 is first connected to the derivative and at an up-regulation of circuit 2 is first connected to the supply line becomes, whereby after a few sailing operations the pressures of the two circles equalize again, and the piston 11 moves back into the middle position shown in FIG. 1. The connecting rod 6 is in the middle position symmetrically aligned to both control valves, which means that they are operated synchronously.

If the pressure P ^ is less than P «», the Set the position of the two control slides shown in Fig. 3, i.e. in the case of a limiting process, first circle 2 with the Lead connected and with an up-regulation process first the circuit 1 is connected to the supply line.

In order to enable the connecting rod 6 to be shifted upwards or downwards by the level sensor 7 the piston-cylinder unit 5 em. pivotally attached at one end. The middle position of the piston 11 is ensured by a spring acting in both directions of displacement. One end position of the spring is shown in Fig. 2, the other in Fig. 3- The pretensioning of the spring makes a stable one The behavior of the regulation is ensured by this only above a certain pressure difference between the two circuits 1 and 2 are used.

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According to a further embodiment of the invention, the stabilizer 22 can instead of, as shown in FIG. 1, as Counter cylinder also in a single double-acting piston-cylinder unit to get integrated.

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Claims (3)

Expectations Process for producing equal pressures in the hydroeumatisehen or pneumatic spring elements or groups of a pendulum axle of motor vehicles with hydraulic or pneumatic stabilization and separate hydraulic or pneumatic circuits controlled by their own control valves, characterized in that depending on the pressure ratio of the two hydraulic or pneumatic circuits fl, 2) the control valves (3) 4) for the two circuits automatically be adjusted against each other so that when the suspension is actuated by adjusting the valve opening times against each other a pressure equalization of the two circles is achieved, whereupon the adjustment is reversed and the Control valves work synchronously. 2. Device for performing the method according to claim 1, characterized in that a resiliently held in the central position, double-acting piston-cylinder unit (5) is provided is, which, acted upon by the pressures of the two hydraulic or pneumatic circuits (1, 2), a connecting rod (6) between a level sensor (7) attached in the center of the axis and the two control valves (3 »4 ·) so that the control valves in the sense of a pressure equalization of the two circles when actuating the suspension, the circle with the higher pressure rather open when de-energizing or rather supply the circuit with the lower pressure with pressure medium when regulating up. 3. Apparatus according to claim 2, characterized in that the connecting rod (6) has a two-armed lever (8), one free end with the level sensor (7) and the other free end pivotable via two with the end 409813/0066 connected rods (9) coupled to the control valves (3, 4) and the end of the piston rod (10) of the piston-cylinder unit (5) is the pivot point of the two-armed lever (8) forms, the arrangement of the rods is such that in the middle position of the piston (11) the rod (6) is aligned symmetrically to a center line and when the piston (11) is in contact with one of the cylinder walls The control slide (12) of the control valves (3, 4) are offset from one another by a certain amount. 409818/0066