DE102020102217B4 - Filter arrangement for a hydraulic system of a vehicle - Google Patents

Abstract

Filter arrangement (2) for a hydraulic system (32) of a vehicle (28), comprising:an inlet (4);an outlet (6);at least two filter branches (8a, 8b) connected to the inlet (4) and the outlet (6). );wherein each filter branch (8a, 8b) has a check valve (14) directed towards the inlet (4) and opening towards the outlet (6) and a filter (12) connected in series therewith for hydraulic fluid;wherein the at least two filter branches (8a, 8b) form an uninterrupted, direct parallel connection;wherein the filter branches (8a, 8b) have the same effective lengths; andwherein the line diameters of the line sections in each of the filter branches (8a, 8b) are identical.

Description

TECHNICAL FIELD

The invention relates to a filter arrangement for a hydraulic system of a vehicle. The invention further relates to a hydraulic system of a vehicle and a vehicle with at least one hydraulic system integrated therein.

BACKGROUND OF THE INVENTION

Hydraulic systems in vehicles can solve a variety of different tasks by providing high-pressure hydraulic fluid through a central pump and directing it to various hydraulic devices in the vehicle. These can provide very high forces and moments and are easy to implement. In addition to the individual hydraulic consumers, a hydraulic system also has a reservoir with hydraulic fluid, a pump and at least one filter. The pump removes the hydraulic fluid from the reservoir and supplies it under high pressure to a hydraulic line to which the hydraulic consumers are connected. These are selectively supplied with the pressurized hydraulic fluid via valves. Due to, among other things, wear on the hydraulic consumers and the lines, material particles can get into the hydraulic fluid over time. The filter can filter this out of the hydraulic fluid before it is returned to the reservoir.

It is known to use double or duplex filters, particularly in stationary applications, which have two separate filter cartridges through which the hydraulic fluid flows selectively and not simultaneously. For this purpose, a switch is provided which directs the volume flow either through one or the other filter cartridge. Depending on the size of the hydraulic system, different sized filters are used.

The GB 1 151 969 A describes a filter in a hydraulic circuit in which the direction of flow is sometimes reversed. The filter includes filter elements arranged in individual housings extending from a manifold housing having an inlet chamber and an outlet chamber from which openings open into the housings, and a system of valves ensuring flow through the elements are always directed inwards, regardless of which passage serves as a temporary inlet to the housing. A ball abuts one of the seats in the inlet chamber and a spool valve closes one end of the outlet chamber. When the flow is reversed, the valves are moved to their other positions, the valve being moved by the pressure applied across the passages. Each filter housing may contain a check valve, and a bypass valve with a valve position indicator is connected between the inlet chamber and the outlet chamber. The valve can be replaced with two separate check valves and the housing can be split laterally so that additional sections can be inserted between the end sections, which contain a continuation of the inlet chamber and the outlet chamber and support additional filter housings. The ball valve can also be replaced with two separate check valves.

The DE 27 33 718 C2 describes a filter head for individual filters that can be connected in parallel to form a filter battery, each with a filter pot that accommodates the replaceable filter insert. On opposite sides of the filter head there are connecting flanges and two straight, parallel channels extending into the flanges for the passage of liquid, each of which is connected to the filter chamber via a liquid inlet or return. The liquid inlet is arranged correspondingly far laterally offset from it. The liquid inlet and the liquid return run in a straight line to the filter chamber and are arranged parallel to one another, with the outlet channel and the liquid return connected to it running in the central plane of the filter.

The DE 43 23 893 C1 describes a filter head with a housing part to which two alternating filter pots, each with a filter element, are connected. The filter head each has an inlet opening, an outlet opening and a switching valve, which selectively connects the inlet opening to a first supply line connected to the first filter element or to a second supply line connected to the second filter element. The two supply lines and the two discharge lines lie approximately on the same transverse plane as the inlet and outlet openings, with the transverse plane intersecting the longitudinal center axis of a filter element at a right angle.

The DE 83 31 792 U1 describes a filter head for accommodating two or more filter chambers connected in parallel for ultra-fine filtration, each with a single inflow and outflow opening and a rotary slide for alternately switching off at least one filter chamber. The rotary valve is in exclusive and simultaneous contact with the unfiltered medium of all filter chambers and only closes alternately access to one of the filter chambers. Each filter chamber is equipped with an upstream blocking check valve on the downstream side.

SUMMARY OF THE INVENTION

In the prior art, the integration of filters in hydraulic systems usually requires correct dimensioning of the filter and its connections. In the series production of vehicles with sometimes different hydraulic systems, a greater variety of components can be expected. At the same time, in safety-critical applications it must be ensured that individual components, such as filters, do not lead to a failure of the entire hydraulic system in the event of a malfunction or failure.

Consequently, an object of the invention is to propose an alternative filter arrangement that can be easily adapted to expected volume flows, can be manufactured as inexpensively as possible and at the same time offers a high level of safety.

The task is solved by a filter arrangement with the features of independent claim 1. Advantageous embodiments and further developments can be found in the subclaims and the following description.

A filter arrangement for a hydraulic system of a vehicle is proposed, the filter arrangement having an inlet, an outlet, at least two filter branches connected to the inlet and the outlet, each filter branch having a check valve directed towards the inlet and opening towards the outlet and a check valve connected thereto Has a series-connected filter for hydraulic fluid, and wherein the at least two filter branches form an uninterrupted, direct parallel connection. The filter branches have the same effective lengths and the line diameters of the line sections in each of the filter branches are identical.

The inlet can be a pipe connection to which all filter branches are connected. This could be realized via a branch or a distributor with one inlet and several outlets. In the simplest case it can be a T-piece on which two filter branches are arranged. The outlet can be designed analogously and can have a pipe connection to which all filter branches are connected.

The filter arrangement has two or more filter branches, each of which has a check valve. This can be arranged downstream of the filter and connect the filter to the outlet. Hydraulic fluid that is pumped into the inlet using a hydraulic pump gets into the relevant filter of the filter branch. There the hydraulic fluid flows through the filter and the check valve and is directed to the outlet. The outlet of the filter arrangement can then be connected to a hydraulic line that leads to valves, hydraulic consumers or the like.

A plurality of filter branches, which are provided between the inlet and the outlet, are arranged in an uninterrupted parallel connection. This should be understood to mean that the filters of all filter branches are connected directly to the inlet and cannot be selectively switched on or off via a switchable distributor. As a result, they are always all flowed through by the hydraulic fluid flowing into the inlet.

The particular advantage of such an arrangement is that, in contrast to the prior art, hydraulic fluid flows through several filter branches at the same time. The individual filter branches could be standardized so that they can be used in many different hydraulic systems with simple adjustment of the required number of filter branches. A filter branch could be used as a module, for example. By selecting the number of filter branches, an easy adjustment to the desired filter capacity can be made. For example, smaller hydraulic systems could only have two filter branches. Larger hydraulic systems could be equipped with three, four or more filter branches.

Thanks to the direct parallel connection, the volume flow of the hydraulic fluid can be distributed evenly across all filter branches. This creates partial volume flows through the individual filter branches, which together represent the total volume flow. Ideally, i.e. if the hydraulic fluid is not contaminated, the partial volume flows are identical if all filter branches are identical. At the outlet, the partial volume flows are combined again to form the total volume flow and transported to the outside through the outlet.

If there is more contamination in one of the filter branches than in the other filter branches, the flow resistance in the relevant filter branch is greater than in the others, so that the partial volume flow there is reduced. As a direct consequence, it increases in the remaining filter branches. Over time, more contamination could build up in the other filter branches, so that the flow resistance also increases there. Consequently, the partial volume flows in the filter arrangement can always adapt to one another over time and the filters are stressed evenly. A failure, ie the complete clogging of one of the filters, cannot lead to a failure of the entire filter arrangement.

It is not necessary to design individual, individually dimensioned filters, since the filter arrangement can be modular and the desired capacity can always be provided by connecting individual filters in parallel. The cost of the filter arrangement can therefore be reduced overall due to the use of a consistent type of filter. The provision of a switching valve or the like is not required due to the desired parallel flow through several filters, which also has a positive effect on the manufacturing costs and weight.

The fact that the filter branches have the same effective lengths can be understood to mean that a geometric distance or running length between the inlet and the outlet over a filter branch is the same. If all filter branches are equipped with the same effective length, the same boundary conditions for the flow are present. The filter branches therefore have, in addition to the respective filter and the respective check valve, line sections whose overall lengths are identical for all filter branches. The differences in flow resistance resulting from individual line lengths do not have to be compensated for. This is particularly true with identical line diameters.

In a further advantageous embodiment, the filter branches can each have a bypass line that bridges the respective filter branch, the bypass line each having a bypass valve that is designed to open from a predetermined differential pressure. The predetermined differential pressure can correspond to approximately double or triple the differential pressure that results from conventional filter operation. If all filters are so clogged that a very high differential pressure builds up across all filters, hydraulic fluid can still flow through, but then largely without filtering.

The filter branch preferably has a differential pressure sensor for detecting the pressure drop across the check valve and the filter, wherein the differential pressure sensor can be connected to a display device to signal excessive contamination. The differential pressure sensor can be connected to a port upstream of the filter and a port downstream of the check valve and can continuously determine the differential pressure across the filter branch. The display unit can be an external display unit and essentially refers to a unit that is designed to detect, evaluate, display, store or generally monitor a delivered measured value from the differential pressure sensor. For example, a maintenance notice could be generated from a single or multiple exceeding of a specified limit pressure. If there is a maintenance notice for a filter in a filter branch, it may be appropriate to replace the filter in question.

The invention further relates to a hydraulic system, comprising a reservoir, a pump and a filter arrangement according to the previous explanation.

In an advantageous embodiment, the filter arrangement is arranged in a forward line and/or a return line of the hydraulic system.

Finally, the invention relates to a vehicle having a filter arrangement according to the previous explanation and/or an aforementioned hydraulic system.

The vehicle is particularly preferably an aircraft.

BRIEF DESCRIPTION OF THE FIGURES

• 1 zeigt eine schematische, blockbasierte Darstellung einer Filteranordnung.
• 2 zeigt ein Flugzeug mit einem Hydrauliksystem und einer darin integrierten Filteranordnung.

Further features, advantages and possible applications of the present invention result from the following description of the exemplary embodiment and the figures. All described and/or illustrated features individually and in any combination form the subject matter of the invention, regardless of their composition in the individual claims or their references. In the figures, the same reference numbers continue to stand for the same or similar objects.

• 1 shows a schematic, block-based representation of a filter arrangement.
• 2 shows an aircraft with a hydraulic system and a filter arrangement integrated therein.

DETAILED EXAMPLE PRESENTATION

EMBODIMENTS

1 shows a filter arrangement 2 for a hydraulic system of a vehicle. The filter arrangement 2 has an inlet 4 and an outlet 6, between which two filter branches 8a and 8b connected in parallel extend. The inlet 4 could be in fluid communication with a hydraulic pump, not shown here, with the outlet 6 could be connected to a hydraulic line or a reservoir. The hydraulic pump transports hydraulic fluid into the inlet 4 and out of the outlet 6. As the flow flows through the filter arrangement 2, it is filtered.

For example, a distributor 10 in the form of a branch as a T-piece is connected to the inlet 4 and divides the volume flow of the hydraulic fluid between the two filter branches 8a and 8b. In each filter two 8a, 8b there is a filter 12 which filters out particles or other contaminants from the hydraulic fluid.

A check valve 14 is arranged downstream of the filter 12 and can be opened in the direction of flow towards the outlet 6. This specifies the possible flow direction. At the outlet 6, for example, a combining element 16 is arranged in the form of a T-piece, which combines the partial volume flows from the filter branches 8a and 8b into a total volume flow. In addition, a bypass line 18 with a bypass valve 20 is provided in each filter branch 8a and 8b, the bypass valve 20 only being opened at a certain differential pressure. The bypass valve 20 could be constructed similarly to a check valve 14, but only open using an integrated locking spring from a differential pressure that is to be expected in the case of a very heavily clogged filter 12. The bypass line 18 extends from a first connection point 22 located upstream of the filter 12 to a second connection point 24 arranged downstream of the check valve 14. The effective, flow-through lengths of both filter branches 8a and 8b are identical, so that the same flow conditions in the filter branches 8a with uncontaminated hydraulic fluid and 8b result. The cable diameters are identical.

The filter arrangement 2 is useful in order to variably adapt a filter capacity to a desired hydraulic system. By adding additional filter branches in parallel, a larger filter capacity can be achieved. All filter branches are constructed identically, so that the variety of components is as minimal as possible. The filter arrangement 2 is still redundant.

It is provided, for example, to monitor the individual filters 12 with regard to their degree of contamination. For this purpose, sensors 26 are provided which monitor the differential pressure in each filter branch 8a and 8b. For example, they can be connected to a higher-level system of a vehicle or a control unit of the hydraulic system and generate a maintenance notice as soon as a certain limit value is exceeded once, several times or permanently.

A hydraulic fluid flowing into the inlet 4 is divided evenly at the branch 10. Contamination is collected by the filters 12 in both filter branches 8a and 8b. If the flow resistance in one of the two filter branches 8a and 8b changes more strongly than in the other, the partial volume flows change, so that a higher partial volume flow flows through the less contaminated filter branch 8a and 8b. As a result, more contamination can accumulate there, so that the ratio of the partial volume flows becomes equal again. The filters of both filter branches 8a and 8b can therefore be stressed evenly.

Finally shows 2 an aircraft 28 with a fuselage 30 in which a hydraulic system 32 is arranged, which has a filter arrangement 2 according to the description above.

In addition, it should be noted that “having” does not exclude other elements or steps, and “a” or “an” does not exclude a plurality. Furthermore, it should be noted that features that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features of other exemplary embodiments described above. Reference symbols in the claims are not to be viewed as a limitation.

REFERENCE MARKS

2

Filter arrangement

4

inlet

6

outlet

8a, 8b

Filter branch

10

Distributor

12

filter

14

check valve

16

Unification element

18

Bypass line

20

Bypass valve

22

first connection point

24

second connection point

26

Differential pressure sensor

28

Airplane

30

hull

32

Hydraulic system

Claims (7)

Filter arrangement (2) for a hydraulic system (32) of a vehicle (28), comprising: an inlet (4); an outlet (6); at least two filter branches (8a, 8b) connected to the inlet (4) and the outlet (6); each filter branch (8a, 8b) having a check valve (14) directed towards the inlet (4) and opening towards the outlet (6) and a filter (12) for hydraulic fluid connected in series therewith; wherein the at least two filter branches (8a, 8b) form an uninterrupted, direct parallel connection; wherein the filter branches (8a, 8b) have the same effective lengths; and wherein the line diameters of the line sections in each of the filter branches (8a, 8b) are identical. Filter arrangement (2). Claim 1 , wherein the filter branches (8a, 8b) each have a bypass line (18) which bridges the respective filter branch (8a, 8b), the bypass line (18) each having a bypass valve (20) which is designed to open from a predetermined to open differential pressure. Filter arrangement (2) according to one of the preceding claims, wherein the filter branch (8a, 8b) has a differential pressure sensor (26) for detecting the pressure drop across the check valve (14) and the filter (12), and wherein the differential pressure sensor (26) can be connected to a display device to signal excessive contamination. Hydraulic system (32), comprising a reservoir, a pump and a filter arrangement (2) according to one of the preceding claims. Hydraulic system (32). Claim 4 , wherein the filter arrangement (2) is in a forward line and/or a return line of the hydraulic system (32). Vehicle, having a filter arrangement (2) according to one of Claims 1 until 3 and/or a hydraulic system (32). Claim 4 or 5 . Vehicle (28) after Claim 6 , where the vehicle (28) is an aircraft.

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