DE102011009079B4 - Hydropic element - Google Patents

Abstract

Hydrop element for vehicle with a housing (2) which contains a hydraulic cylinder (3) and a gas spring (5) which is operatively connected to this via a first separating piston (4) which can be moved from a rest position to a "fully compressed" position, wherein an additional cylinder (9) is formed with a second separating piston (15) which can be displaced from an initial to an end position and a gas-filled first subchamber (18) of the additional cylinder (9) is separated from a second subchamber ( 19) of the additional cylinder (9) separates, and wherein the gas spring (5) is connected on the hydraulic side via a first pipe (27) to the hydraulic cylinder (3) and on the gas side via a second pipe (28) to the first subchamber (18), wherein in the additional cylinder (9) an inner cylinder (14) extending coaxially from the bottom end of the additional cylinder (9) into a sub-region of the interior space is arranged, which at the bottom is marked with d he second pipeline (28) is connected, so that the second separating piston (15) is a stepped piston, which with its front narrower piston part (16) through the side walls of the inner cylinder (14) and with its rear-side wider piston part (17) is guided through the side walls of the side wall area of the additional cylinder (9) adjoining the inner cylinder (14) at the rear.

Description

The invention relates to a hydraulic element for vehicles, in particular tracked vehicles, with a housing which contains a hydraulic damping device and a gas spring that is operatively connected to the damping device via a first separating piston that can be moved from a rest position to a “fully compressed” position.

Hydropneumatic spring-damper elements, which are usually referred to as hydropneumatic elements for short, are from the DE 10 2008 026 680 A1 known. They are used, for example, to dampen vibrations in heavy off-road vehicles (such as tracked vehicles) and essentially consist of a gas volume that acts as a spring and an oil damper that interacts with the gas volume. For this purpose, a separating piston can be provided in a common cylindrical housing, which separates the gas volume from the oil-filled hydraulic volume, so that a spring action of the gas filling takes place that is dependent on the position of the separating piston. In the hydraulic volume there is a load-bearing piston connected to a piston rod, which usually contains throttle bores, so that when the vehicle in question is driven over bumps, the oil compressed by the piston is pressed through the throttle bores into a low-pressure area of the hydraulic volume, resulting in a speed-dependent damping force.

Particularly when hydropower elements are used in military crawler vehicles, the high-frequency movements generate a relatively large amount of heat in these damper elements. The resulting increase in the gas temperature leads to a change in the pressure and force ratios of the gas spring and thus to a change in the static position (equilibrium position of the wheel load and hydraulic element) of the vehicle's piston rod. This then results, among other things, in an undesirable increase in the chain tension and possibly changes in the static position (vehicle height).

To compensate for the temperature of the heat generated in the damper elements, the aforementioned DE 10 2008 026 680 A1 therefore proposed to cool the heating hydraulic oil by means of appropriate cooling elements.

the DE 10 2008 025 482 A1 discloses a movement-dependent damping by means of set dead strokes or the suspension of the damping. During compression, a dynamic pressure is created in front of the orifice of a damping piston, so that the damping is suspended. If the spring travel is greater than the set dead stroke, the damping piston moves against a fixed stop so that the volume of oil to be displaced only has to be pressed through the throttle valve, thus generating the damping.

In known dampers, for example from Hemscheidt Fahrwerktechnik GmbH and Co., two separate gas volumes (primary and secondary gas volume) are used to compensate the temperature of the spring characteristic, in order to passively implement the compensation within the damper.

the DE 34 27 902 A1 describes a control of hydropneumatic spring elements, in particular for motor vehicles. In the spring element, a gas cushion separated from an oil volume by a movable partition creates the spring forces of an oil-displacing spring piston. Control means attached to the dividing wall cause, in the event of changes in load, dividing wall returns in the central position by supplying gas from a high-pressure container or discharging gas in a low-pressure container.

A suspension system for adapting to changing loads on vehicle axles is disclosed in US Pat DE 197 24 015 A1 . A hydraulic accumulator of the suspension system acts on the vehicle axle assigned to it with a predeterminable spring characteristic.

A vehicle with wheels is known from US 2001/0 024 005 A1, the movement between the wheels and the chassis being controlled by dampers. A flow regulator is used to increase the damping forces under a variety of operating conditions.

the WO 2005/073000 A1 deals with a tracked vehicle and a method for influencing the chain tension of a tracked vehicle.

The invention is based on the object of specifying a hydroponic element of the type mentioned at the outset, in which simple temperature compensation is possible.

This object is achieved according to the invention by the features of claim 1. Further, particularly advantageous embodiments of the invention are disclosed in the subclaims.

The invention is essentially based on the idea of mechanically constructing the hydropower element in such a way that temperature compensation is achieved through the use of a stepped gas spring characteristic, the hydropower Element is designed such that the corresponding force level occurs when the static position of the piston rod is reached. For this purpose, a stepped piston and a cylinder, a secondary throttle valve and a high-pressure gas line are integrated into a known hydroponic element, which means that these are also integrated into this.

The hydrop-element now comprises a hydraulic cylinder as a hydraulic damping device with a load-bearing piston which is connected to a hollow piston rod, the oil-filled piston rod being axially displaceable in a cylindrical first housing part from a fully rebounded to a static position to a fully rebounded position is arranged.

The first housing part contains the additional cylinder attached to the bottom end and extending coaxially into the first housing part, with an annular space between the inner surface of the first housing part and the outer surface of the additional cylinder, along which the piston rod can be displaced, such that between An oil channel remains on the piston rod and the outer surface of the auxiliary cylinder. In the additional cylinder there is arranged a second separating piston which is axially displaceable from an initial to an end position and which separates a first subchamber of the inner cylinder filled with gas from a second subchamber of the additional cylinder filled with the hydraulic fluid, the second subchamber with the Interior of the piston rod is connected.

The pneumatic gas spring comprises a second cylindrical housing part containing the first separating piston, which is separated by the first separating piston into a third subchamber on the bottom and a fourth subchamber located axially in front of it, the third subchamber via a second throttle valve and a first pipeline with the annular chamber of the first Housing part and the fourth subchamber are connected to the first subchamber of the additional cylinder via a second pipeline.

The first throttle valve, the dimensions of the second separating piston and the additional cylinder as well as the gas pressure in the second housing part are selected in such a way that when the piston rod is moved from its fully rebounded position to its static position, the second separating piston is moved from its starting position to its end position, without the first separating piston being displaced from its rest position and further displacement of the piston rod after reaching the static position is only possible when the first separating piston - due to the bias of the gas of the gas spring - after reaching the maximum value of a predetermined sudden force curve is displaceable from its rest position.

An inner cylinder, which extends coaxially from the bottom end of the additional cylinder into a partial area of the interior space and is connected to the second pipeline at the bottom, is preferably arranged in the additional cylinder. In addition, the second separating piston is a stepped piston, which is guided with its narrower front piston part through the side walls of the inner cylinder and with its wider piston part at the rear through the side walls of the additional cylinder area in front of the inner cylinder. Due to the force transmission on the stepped piston, it is ensured in a simple manner that the separating piston is not yet displaced until the piston rod has reached the static position.

In a preferred embodiment of the invention, the first and second cylindrical housing parts are arranged parallel to one another in order to obtain the most space-saving structure possible for the hydropower element, the first and second pipelines being integrated into a third housing part connecting the two housing parts.

With the above variant, a robust temperature compensation is realized without the use of sensors and additional assemblies for hydropneumatic suspension and damping elements using only one gas piston. Especially this concept of a hydrops with stepped piston and only one gas volume realizes a simpler construction. The hydrops with stepped pistons and two gas volumes are technically significantly more complex.

With regard to operational safety, there are the advantages that gas loss can be recognized from the outside, with incorrect operation during gas filling being limited to filling a gas volume, since only one gas spring has to be filled. This filling can take place via a central filling interface on the vehicle. For this, the hydrops no longer have to be expanded or completely relieved. Better access to the filling connections is guaranteed. In addition, it is possible to optimize the rebound characteristic; a higher temperature range can be covered. The main piston rod guide can also be designed in one stage, telescoping capability is no longer a requirement.

• 1 einen Längsschnitt durch eine schematische Darstellung eines erfindungsgemäßen Hydrop-Elementes, bei dem die Kolbenstange sich in ihrer „voll ausgefederten“ Position befindet;
• 2 das in 1 dargestellte Hydrop-Element, bei dem sich die Kolbenstange in ihrer statischen Lage befindet;
• 3 das in 1 dargestellte Hydrop-Element, bei dem sich die Kolbenstange in ihrer „voll eingefederten“ Position befindet;
• 4 Diagramme, welche die Federkennlinie des erfindungsgemäßen Hydrop-Elementes zeigen.

Further details and advantages of the invention emerge from the following exemplary embodiments explained with reference to figures. Show it:

• 1 a longitudinal section through a schematic representation of a hydroponic element according to the invention, in which the piston rod is in its “fully rebounded” position;
• 2 this in 1 Hydropic element shown, in which the piston rod is in its static position;
• 3 this in 1 Hydrop-element shown with the piston rod in its "fully compressed"position;
• 4th Diagrams showing the spring characteristics of the hydropol element according to the invention.

In 1 1 denotes a hydropic element, for example for a tracked vehicle, not shown. The hydropic element 1 includes a housing 2 for a hydraulic damping device - a hydraulic cylinder 3 - and for one with the damping device 3 via a first separating piston 4th in operative connection (for example pneumatic) gas spring 5 .

The hydraulic damping device 3 in turn comprises a load-bearing piston 6th that with a hollow piston rod 7th connected is. The piston rod filled with a hydraulic fluid (oil) 7th is in a cylindrical first housing part 8th arranged axially displaceable from a “fully rebounded” position to a “fully rebounded” position via a static position.

The first housing part 8th also contains one attached to the bottom end and extending coaxially into the first housing part 8th extending additional cylinder 9 , being between the inner surface 10 of the first housing part 8th and the outer surface 11 of the additional cylinder 9 an annulus 12th results, along which the piston rod 7th is displaceable, in such a way that between the piston rod 7th and outer surface 11 of the additional cylinder 9 an oil channel 13th remains.

In the additional cylinder 9 is an inner cylinder extending coaxially from the bottom end into a partial area of the interior space 14th arranged. In addition, is in the auxiliary cylinder 9 one as a stepped piston 15th trained second separating piston arranged axially displaceable from a starting position into an end position. The stepped piston 15th becomes with its front narrower piston part 16 through the side walls of the inner cylinder 14th and with its rear, wider piston part 17th through the side walls of the front of the inner cylinder 14th located additional cylinder area and therefore separates the gas-filled first sub-space 18th of the inner cylinder 14th by a second compartment filled with the hydraulic fluid 19th of the additional cylinder 9 . The second subspace 19th is via a first throttle valve 20th with the interior 21 the hollow piston rod containing the oil 7th tied together.

The gas spring 5 comprises the first separating piston 4th containing cylindrical second housing part 22nd that has a third housing part 23 with the first housing part 8th connected and arranged parallel to this.

The second part of the housing 22nd is through the first separating piston 4th in an oil-containing, bottom-side third sub-space 24 and a fourth compartment located axially in front of it and containing gas 25th separated. Here are the third sub-space 24 via a second throttle valve 26th and one in the third housing part 23 running first pipeline 27 with the annulus 12th of the first housing part 8th and the fourth subspace 25th via one also in the third housing part 23 running second pipeline 28 with the first subspace 18th tied together.

The first throttle valve 20th , the dimensions of the stepped piston 15th and the additional cylinder 9 and the gas pressure in the second housing part 22nd are chosen in such a way that when the piston rod is displaced 7th from its "fully sprung" position to its static position ( 2 ) the stepped piston 15th is moved from its starting position to its end position without a displacement of the first separating piston 4th takes place from its rest position.

In the following, based on 1 , the sequence of movements of the hydropic element according to the invention described in more detail. Here is the piston rod 7th “Fully sprung”, the stepped piston 15th is in its starting position and the first separating piston 4th is in its rest position, in which it is at a mechanical stop on its side that delimits the hydraulic fluid (oil). In addition, the gas is preloaded in accordance with the static wheel load and the partial spaces containing the hydraulic fluid are completely filled with oil (bubble-free).

The piston rod 7th then moves from the position "fully extended" ( 1 ) in your in 2 static position shown (state of equilibrium of wheel load and hydropic element). The volume of oil to be displaced according to the piston rod cross-section and the piston stroke moves the stepped piston 15th axially from its starting position to its end position. Both oil volumes are matched to one another. The stepped piston 15th pushes the gas out of the first subspace 18th through the pipeline 28 in the fourth subspace 25th and compresses the already pre-stressed gas according to the displaced compression volume. Due to the power transmission on the stepped piston 15th ensures that the first separating piston is 4th until the static position of the piston rod is reached 7th not moved yet.

The piston rod now moves 7th from the static position to the position "fully compressed" ( 3 ) For example, when the vehicle is driving off-road, the first separating piston is displaced 4th as soon as the pressure on the oil side is higher than on the gas side. Here is the path of the separating piston 4th determined by the volume of oil displaced from the piston rod, and the force curve above the static position depends on the preload of the gas volume.

The mode of operation of the hydropic element according to the invention with regard to temperature compensation when assuming its static position is described below with the aid of the in 4th illustrated spring characteristics explained in more detail. The diagram shows the ones on the pistons 6th exerted force in kN as a function of the displacement of the piston 6th shown in mm.

As can be seen from the spring characteristic curve of the hydropol element according to the invention, denoted by I, it increases during the movement of the piston 6th and thus also the piston rod 7th from the "fully rebounded" position ( 1 ) into the static position ( 2 ) the force due to the movement of the stepped piston 15th and the associated additional compression of the gas in the partial space 25th to. Due to the high pressure in the subspace 25th there is initially no displacement of the first separating piston when the force on the piston is increased 4th . Only after a pressure difference of about 75 kN has been exceeded is the pressure on the side of the first separating piston acted upon by the oil higher than on the side facing the gas, and the piston 6th as well as the piston rod 7th can be (with simultaneous displacement of the separating piston 4th ) to their "fully compressed" position.

Due to the sudden increase in the force in the area of the static position of the piston rod 7th the desired temperature compensation results. Because increases the temperature of the gas in the subspace 25th due to the increase in the oil temperature in the interior 21 the piston rod 7th to, the gas pressure in the subspace increases 25th , but this only makes the first separating piston 4th held in its rest position.

The reference symbol II is in 4th the spring characteristic of the DE 10 2008 026 680 A1 known hydroponic element shown. A sudden increase in force in the area of the static position that is comparable to the spring characteristic curve I is absent with this characteristic curve.

List of reference symbols

1

Hydropic element

2

casing

3

Damping device

4th

first separating piston

5

Gas spring

6th

Pistons

7th

Piston rod

8th

(first) housing part

9

Additional cylinder

10

inner surface

11

outer surface

12th

Annulus

13th

Oil channel

14th

Inner cylinder

15th

second separating piston, graduated piston

16

narrow piston part

17th

wide piston part

18th

first subspace (inner cylinder)

19th

second subspace (additional cylinder)

20th

first throttle valve

21

inner space

22nd

(second) housing part

23

third housing part

24

third subspace

25th

fourth subspace

26th

second throttle valve

27

first pipeline

28

second pipeline

Claims (8)

Hydrop element for vehicle with a housing (2) which contains a hydraulic cylinder (3) and a gas spring (5) which is operatively connected to this via a first separating piston (4) which can be moved from a rest position to a "fully compressed" position, wherein an additional cylinder (9) is formed with a second separating piston (15) which can be displaced from a starting position to an end position and a gas-filled first subchamber (18) of the additional cylinder (9) is separated from a second subchamber ( 19) of the additional cylinder (9) separates, and wherein the gas spring (5) on the hydraulic side via a first pipe (27) with the hydraulic cylinder (3) and is connected to the first subchamber (18) on the gas side via a second pipeline (28), an inner cylinder (14) extending coaxially from the bottom end of the auxiliary cylinder (9) into a subregion of the interior being arranged in the additional cylinder (9), which is connected at the bottom to the second pipeline (28) that the second separating piston (15) is a stepped piston, which with its front narrower piston part (16) through the side walls of the inner cylinder (14) and with its rear-side wider piston part (17) through the side walls of the side wall area of the additional cylinder (9) adjoining the inner cylinder (14) at the rear. Hydrop element according to Claim 1 , characterized in that the hydraulic cylinder (3) comprises a load-bearing piston (6) which is connected to a hollow piston rod (7) filled with a hydraulic fluid, the piston rod (7) in a cylindrical first housing part (8) from a " fully rebounded ”via a static to a“ fully rebounded ”position is arranged to be axially displaceable. Hydrop element according to Claim 2 , characterized in that the first housing part (8) comprises the additional cylinder (9) fastened to the bottom end and extending coaxially into the first housing part (8), wherein between the inner surface (10) of the first housing part (8) and the outer surface (11) of the additional cylinder (9) results in an annular space (12) along which the piston rod (7) can be displaced. Hydrop element according to one of the Claims 1 until 3 , characterized in that the pneumatic gas spring (5) comprises a second cylindrical housing part (22) containing the first separating piston (4), which through the first separating piston (4) into a third subchamber (24) on the bottom and a fourth subchamber located axially in front of it (25) is separated, the third subchamber (24) via a second throttle valve (26) and the first pipe (27) with the annular space (12) of the first housing part (8) and the fourth subchamber (25) via the second pipe (28) are connected to the first subchamber (18) of the additional cylinder (9). Hydrop element according to one of the Claims 1 until 4th , characterized in that a throttle valve (20), the dimensions of the second separating piston (4) and the additional cylinder (9) as well as the gas pressure in the fourth subchamber (25) of the second housing part (22) are selected such that when the Piston rod (7) is moved from its "fully rebounded" position to its static position, the second separating piston (15) is moved from its starting position to its end position without the first separating piston (4) being shifted from its rest position and another Movement of the piston rod (7) after reaching the static position is only possible when the pressure on the side of the first separating piston (4) exposed to the oil is higher than on the side facing the gas and the gas spring (5) is preloaded. is overcome. Hydrop element according to Claim 4 or 5 , characterized in that the first housing part (8) and the second housing part (22) are arranged parallel to one another, and that in a third housing part (23) connecting the two housing parts (8, 22) the first and second pipelines (27, 28 ) are integrated. Vehicle, characterized by a hydroponic element according to one of the Claims 1 until 6th . Vehicle after Claim 7 , characterized in that it is a tracked vehicle.

Images