Steering system for vehicle, in particular commercial vehicle

Abstract

The invention relates to an electro-hydraulic steering system (100) for a vehicle, in particular a commercial vehicle, comprising: at least one steering gear (102), in particular a spindle steering gear, having at least one steering gear housing (104); at least one first hydraulic assembly (106), in particular an electro-hydraulic assembly, which can be fastened to the steering gear housing (104); and at least one second hydraulic assembly (108), in particular an electro-hydraulic assembly, which can be fastened to the steering gear housing (104), one or more components of the first hydraulic assembly (106) being at least partially integrated in a first housing block (110) and one or more components of the second hydraulic assembly (108) being at least partially integrated in a second housing block (112), or one or more components of the first hydraulic assembly (106) and the second hydraulic assembly (108) are at least partially integrated in a common housing block. The invention also relates to a vehicle, in particular a commercial vehicle, equipped with such a steering system.

Description

TECHNICAL FIELD

[0001] The invention relates to an electrohydraulic steering system for a vehicle, in particular a commercial vehicle. Furthermore, the invention also relates to a vehicle, in particular a commercial vehicle, equipped with the electrohydraulic steering system. BACKGROUND

[0002] In conventional steering systems of commercial vehicles, the hydraulic components, such as filters, valves, etc., and / or the control components, such as actuators, etc., require a large installation space, which has a negative effect on the power density and the performance and functionality density of these steering systems.

[0003] In the prior art, steering systems for vehicles, in particular commercial vehicles, have already been disclosed.

[0004] Therefore, DE 10 2016 112 332 A1 discloses a method for monitoring a regulator module for operating an adjustment drive, in particular an adjustment drive of a steering system. SUMMARY

[0005] The task of the invention is to advantageously expand the electrohydraulic steering system of the type described above, in particular in such a way that the system has a higher power density, can be more easily switched with fewer components and / or a simpler line configuration, and thus potential sources of failure can be eliminated.

[0006] According to the invention, this task is solved by an electrohydraulic steering system having the features of claim 1. According to this, an electrohydraulic steering system for a vehicle, in particular a commercial vehicle, is provided, which has: - at least one steering transmission, in particular a screw spindle steering transmission, with at least one steering transmission housing; - at least one first hydraulic assembly, in particular an electrohydraulic assembly, which can be fastened on the steering transmission housing; and - at least one second hydraulic assembly, in particular an electrohydraulic assembly, which can be fastened on the steering transmission housing; wherein one or more components of the first hydraulic assembly are at least partially integrated in a first housing block, wherein one or more components of the second hydraulic assembly are at least partially integrated in a second housing block, or one or more components of the first hydraulic assembly and the second hydraulic assembly are at least partially integrated in a common housing block.

[0007] The core idea of the present application is that one or more components of the first hydraulic assembly or the second hydraulic assembly can be at least partially integrated in the first and second housing blocks or in a common housing block. This enables a very high power density by means of internal pipe guidance within the housing blocks, whereby the elasticity (and thus the inertia) in the steering system can be eliminated and additional sources of failure can be eliminated. It is also possible to provide that all components of the first and second hydraulic assemblies can be integrated in the first and second housing blocks, respectively, or in the common housing block. "Integrated" in this context is understood to mean that the one or more components do not necessarily have to be completely structurally integrated or embedded in the housing blocks (for example, for a switching valve, the valve core and part of the interface can be integrated, while the control or actuation region and possibly the external interface can be arranged outside the housing blocks or connected to the housing blocks by means of flanges). The valve blocks can be designed in such a way that the holes, pipes, wall structures, etc. required for the integration of the one or more components are introduced in a single piece of material, thus forming the housing blocks. The common housing block can here contain all components of the first and second hydraulic assemblies. Alternatively, it is also conceivable that the common housing block only partially contains components of the first and second hydraulic assemblies. The common housing block can be made of a single piece of material provided in one piece (for example, from an aluminum alloy). The first and second hydraulic assemblies are understood to be independent assemblies, wherein they differ at least in one function and / or one structural component.

[0008] Alternatively, the common housing block can have a first housing block and a second housing block. This design enables a two-piece design of the common housing block, which in turn enables a variable design of the first and second hydraulic assemblies. The first and second housing blocks can be fastened to one another here (for example, by means of screws or welding or other suitable methods).

[0009] It is further possible to provide that the first hydraulic assembly has at least one hydraulic pump and at least one electric motor for driving the hydraulic pump, by means of which hydraulic oil can be supplied to the steering transmission and / or the steering transmission can be controlled. By integrating the hydraulic pump at least partially into the first housing block, the flow path from the pump to the steering transmission (for supplying and actuating the steering transmission) can be shortened, so that the steering transmission can be actuated and supplied with hydraulic fluid (for example, hydraulic oil adapted to the steering transmission) more quickly, more precisely and with less pipe losses.

[0010] Furthermore, the first hydraulic assembly can have at least one first line, which can be connected to the at least one first working chamber of the steering transmission housing and through which hydraulic fluid can be supplied to the first working chamber and / or the first working chamber can be controlled. Furthermore, the first hydraulic assembly can have at least one second line, which can be connected to the at least one second working chamber of the steering transmission housing and through which hydraulic fluid can be supplied to the second working chamber and / or the second working chamber can be controlled. By arranging the first and second lines inside the first or second housing block or the common housing block, the length of the lines can be substantially shortened, so that the steering transmission can be controlled and supplied with hydraulic fluid more quickly and precisely and with less line losses. Furthermore, the first and second lines can be introduced directly into the respective housing block, for example in the form of holes, slots or other recesses, so that a very simple configuration of the lines is possible.

[0011] Furthermore, it is conceivable that the hydraulic pump can be configured as a bidirectional hydraulic pump with a first and a second delivery direction and connected to the first and second lines, wherein the hydraulic pump can be configured to pressurize the first line according to the first delivery direction and the second line according to the second delivery direction. Since the steering transmission piston is supported in the application of the steering force, the two working chambers on both sides at their respective end sides and configured there must be pressurized in different directions, a bidirectional pump is particularly advantageous for this application. By changing the rotational direction of the bidirectional pump, its delivery direction is automatically changed according to the function, so that the pressurization of the two working chambers of the steering transmission via the first and second lines can be achieved very easily. This configuration thus enables an extremely efficient pump configuration for the respective adapted application purpose in the steering transmission.

[0012] Furthermore, it is proposed that the second hydraulic assembly is configured as a backup assembly and is connected to the steering transmission in at least one failure state and / or at least one inactive state of the steering system. If a failure state occurs in the first hydraulic assembly, the hydraulic fluid or the hydraulic fluid can no longer flow out of and into the first or second working chamber, so that the steering transmission can no longer be operated. For this reason, the second hydraulic assembly can be provided, which short-circuits the connection between the first and second working chambers in the failure state, so that the steering transmission can still be controlled and thus enables the commercial vehicle to continue to be steered safely. Alternatively or additionally, the backup assembly can also be controlled in the inactive state, for example by means of a control and / or regulating device of the steering system, so that the connection between the two working chambers is freely accessible, so that in the case of an inactive state in the second hydraulic assembly, another function can be efficiently implemented for the steering system.

[0013] Furthermore, it can be provided that the second hydraulic assembly has at least one hydraulic filter element and at least one reserve switching valve. The reserve switching valve essentially fulfils the following function: The reserve switching valve can in principle be switched from a closed position into a through position and vice versa, so that both working chambers of the steering transmission are connected by the second assembly, and the vehicle can still be steered. This is advantageous, in particular in the event of a fault, since a hydraulic short circuit is achieved by the second assembly, the working chambers of the steering transmission are still connected, and thus the steering function of the steering transmission is also ensured. In the closed position of the reserve switching valve, the second assembly is not active, and the control of the steering transmission and the supply of hydraulic fluid are achieved by the first assembly. The integration of the hydraulic filter element into the second assembly has the advantage that, in particular in the inactive state, the second assembly can also assume an additional function, namely the filtering of the hydraulic oil.

[0014] Furthermore, it can be provided that the hydraulic filter element and the reserve switching valve form a series circuit. With this circuit, the hydraulic fluid can be passed through the hydraulic filter element in a controllable manner and with the shortest possible flow path. The flow resistance can thereby be reduced, and the efficiency of the steering system when filtering the hydraulic fluid, or hydraulic oil, can be increased.

[0015] Furthermore, it can be provided that the second hydraulic assembly has at least one further first line and at least one further second line. In particular, the further first line can be connected to the first working chamber of the steering transmission housing, and the further second line can be connected to the second working chamber of the steering transmission housing. By arranging the further first and further second lines inside the respective housing block (depending on the design), their line length is extremely short, so that in the event of a fault or in the inactive state, the steering transmission can be supplied with hydraulic oil more quickly, more precisely and with less line loss. Furthermore, the further first line and the further second line can be introduced directly into the respective housing block (for example as a hole, slot or other recess), so that an extremely simple configuration of the lines can be achieved.

[0016] It is further proposed that in the non-activated state and / or in the fault state, the backup switching valve is switched to the through position, such that the first working chamber and the second working chamber are connected at least via the further first line and the further second line and via the hydraulic filter element and the backup switching valve. The first state is the fault state, in which, for example, the power supply is interrupted, and in which the reset spring can switch the backup switching valve to the through position, such that the two working chambers of the steering transmission are connected, and thus the vehicle can still be steered. The second function, or rather the second state, is the non-activated state, in which no future steering support of the steering system is required (and thus no pressurization of the steering transmission). In this state, the further functional configuration of the second assembly (i.e. the filtration of the hydraulic oil) can advantageously be utilized. Since the hydraulic pump must be continuously operated, a certain steering resistance can be perceived by the driver, and only in the already operating hydraulic pump can the steering force support be generated sufficiently quickly. Thus, in the non-activated state, the pump operation can be utilized such that the hydraulic pump pressurizes one of the two working chambers, such that the pressurization must be below a pressure threshold, which triggers the actual steering support (which is achieved by the system inertia and the friction). In this case, the hydraulic oil flows from the pressurized working chamber through the backup assembly to the unpressurized working chamber of the steering transmission, and vice versa (in the case of a reverse pressurization). Since the filter element is arranged in the backup assembly, the hydraulic oil can be filtered with very high energy efficiency.

[0017] Furthermore, the backup switching valve can be configured as a two-position two-way magnetic valve and can have at least one valve core and at least one magnetic coil for operating the valve core. Here, a change in the switching position of the valve core can trigger an induced voltage in the magnetic coil. The switching position is an important monitoring variable or rather an important monitoring parameter for the system safety, which should always be precisely monitored. By introducing a coil current by means of the induced voltage in the magnetic coil, this can be detected, so that the valve core position can be really simply monitored. Furthermore, the two-position two-way magnetic valve is a simply configured valve with a correspondingly reduced failure or failure probability, which positively contributes to the system safety.

[0018] Furthermore, the second hydraulic assembly can have at least one bridge circuit, which has four external branches and one bridge branch, wherein the four external branches can be connected to one another by four external nodes. Such a bridge circuit enables a unidirectional flow through the hydraulic filter element, even if the flow direction in the further first line and the further second line changes depending on the pressurization change of the two working chambers within the steering transmission housing (see the above description). Thereby, the hydraulic filter element can be more simply configured, since it is always only flowed through in a defined flow direction.

[0019] It is further possible to provide that the bridge branch is configured in a series circuit configuration comprising a hydraulic filter element and a backup switching valve. This configuration of the bridge branch enables, inter alia, a one-way flow through the hydraulic filter element, with the advantages already explained in the above paragraph.

[0020] It is further possible to provide that the bridge circuit is connected to a further first line and a further second line by means of two external nodes, wherein the bridge branch is connected to two further external nodes. This circuit results in a symmetrical attachment or connection of the further first line and the further second line and the bridge branch, so that the line length in both flow paths, or in both flow directions, is identical, and thus identical control behavior between the two opposite movement directions of the control piston of the steering transmission is produced (for example in the event of a fault condition).

[0021] It is further possible according to the application to provide a vehicle, in particular a commercial vehicle, with at least one electronic hydraulic steering system as described above. All advantages and technical effects that can be achieved in connection with the steering system according to the application, whether individually or in combination, apply equally to the vehicle according to the application. The vehicle can in particular be a commercial vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0022] Further details and advantages of the application will be explained in detail below with reference to embodiments shown in the drawings.

[0023] which shows: Figure 1 Schematic representation of the circuit arrangement of an embodiment of the steering system according to the application. DETAILED DESCRIPTION

[0024] Figure 1 Schematic representation of the circuit arrangement of an embodiment of the steering system according to the application.

[0025] The electronic hydraulic steering system 100 for a commercial vehicle has a steering transmission 102 in the form of a screw spindle steering transmission 102, which in turn has a steering transmission housing 104.

[0026] The screw spindle steering transmission 102 can be configured as a ball screw spindle steering transmission, wherein other transmission types are also conceivable.

[0027] The electronic hydraulic steering system 100 further has a first hydraulic assembly 106, which is fastened on the steering transmission housing 104.

[0028] The first hydraulic assembly 106 is configured in the form of an electronic hydraulic assembly 106.

[0029] The electronic hydraulic steering system 100 further has a second hydraulic assembly 108, which is fastened on the steering transmission housing 104.

[0030] The second hydraulic assembly 108 is also configured as an electro-hydraulic assembly 108.

[0031] The fastening of the first hydraulic assembly 106 and the second hydraulic assembly 108 on the steering gear housing 104 can be realized by means of respective flange connections, but Figure 1 is not shown in the schematic illustration.

[0032] As Figure 1 is shown, a plurality of components of the first hydraulic assembly 106 are at least partially integrated into the first housing block 110.

[0033] Correspondingly, a plurality of components of the second hydraulic assembly 108 are at least partially integrated into the second housing block 112.

[0034] According to Figure 1 , the first housing block 110 and the second housing block 112 are configured as structurally separate blocks and are fastened at different locations on the steering gear housing 104.

[0035] For example, the first housing block 110 and the second housing block 112 can be fastened at opposite locations on the steering gear housing 104 (i.e. in a 180° orientation to each other).

[0036] It is likewise conceivable that the first housing block 110 and the second housing block 112 can also be fastened on the steering gear housing 104 in a 90° or 270° orientation to each other.

[0037] According to an alternative configuration of the housing blocks of the steering system 100, one or more components of the first hydraulic assembly 106 and the second hydraulic assembly 108 can also be at least partially integrated into one common housing block (not shown in Figure 1 ).

[0038] The common housing block can have the first housing block 110 and the second housing block 112, or be configured from these two blocks 110, 112, or alternatively also be configured as a one-piece housing block (made from one piece of material).

[0039] Furthermore, the steering system 100 has an electronic control and / or regulating device 114 for controlling and / or regulating the first hydraulic assembly 106 and the second hydraulic assembly 108.

[0040] The components of the first hydraulic assembly 106 have a hydraulic pump 116 and an electric motor M for driving the hydraulic pump 116 as components.

[0041] The hydraulic pump 116 is configured as a double-acting (or bidirectional) hydraulic pump with a first delivery direction and a second delivery direction.

[0042] The first hydraulic assembly 106 further comprises a first line 118 which is connected to the first working chamber 122 of the steering gear housing 104.

[0043] The first hydraulic assembly 106 thus further comprises a second line 120 which is connected to the second working chamber 124 of the steering gear housing 104.

[0044] According to Figure 1 It can be seen that the hydraulic pump 116 is connected to the first line 118 and to the second line 120.

[0045] It is also conceivable, instead of the above-described configuration, to provide only one single-acting hydraulic pump which is connected to the first line 118 and to the second line 120 by means of a corresponding switching valve (not shown) which, depending on the switching logic, can connect the hydraulic pump to the first line 118 or to the second line 120. Figure 1

[0046] It is also conceivable, instead, to provide two hydraulic pumps, wherein a corresponding one of the pumps is connected to or corresponds to the first line 118 or to the second line 120.

[0047] According to Figure 1 The first line 118 extends from a first pressure outlet of the hydraulic pump 116 to an interface of the steering gear housing 104 which opens into the first working chamber 122.

[0048] The second line 120 extends from a second pressure outlet of the hydraulic pump 116 to an interface of the steering gear housing 104 which opens into the second working chamber 124.

[0049] In the first line 118 and in the second line 120, respectively, a hydraulic filter element can be arranged.

[0050] Furthermore, according to Figure 1 In the first line 118, a pressure sensor is arranged.

[0051] Furthermore, in the second line 120, a pressure sensor and a temperature sensor are arranged.

[0052] It is additionally or alternatively conceivable that, in the first line 118, a temperature sensor is also arranged.

[0053] The first hydraulic assembly 106 further has a hydraulic tank which can be completely or partially integrated into the first housing block 110.

[0054] It is also alternatively conceivable that the hydraulic tank can also be connected to the first housing block 110 by means of a flange.

[0055] According to Figure 1 ​The hydraulic tank is only shown schematically, it is therefore also conceivable that the hydraulic pump 116 is integrated in the tank.

[0056] Alternatively or additionally, the electric motor, the hydraulic tank and the hydraulic pump 116 can also be connected to one another by flanges and connected by corresponding lines (not shown in Figure 1 ).

[0057] The hydraulic tank is also equipped with a pressure sensor and a temperature sensor for monitoring the pressure and the temperature of the hydraulic oil in the tank.

[0058] The second hydraulic assembly 108 is configured as a backup assembly, which is connected to the steering transmission 102 in a failure state of the steering system 100.

[0059] Alternatively or additionally, the second hydraulic assembly 108 can be connected to the steering transmission 102 in a deactivated state of the steering system 100.

[0060] The term "connected" as used herein is to be understood in the sense that a throughflow path is provided between the working chambers 122, 124 of the steering transmission 102 by means of the second hydraulic assembly 108.

[0061] The second hydraulic assembly 108 as a component has, inter alia, a hydraulic filter element 126 and a backup switching valve 128.

[0062] The hydraulic filter element 126 and the backup switching valve 128 form a series circuit.

[0063] The hydraulic filter element 126 is arranged upstream with respect to the backup switching valve 128.

[0064] A pressure sensor 144 for monitoring the filter state and a bypass check valve (or filter check valve) 146 can be arranged in parallel to the hydraulic filter element 126.

[0065] The pressure sensor 144 can be configured as a differential pressure sensor, or alternatively, as two separate pressure sensors or pressure switches with an adjustable triggering threshold (not shown in Figure 1 ).

[0066] The pressure sensor 144 described above, the other currently described sensors of the first hydraulic assembly 106 and the electric motor M are connected by corresponding lines to the electronic control and / or regulating device 114 (not shown in Figure 1 ).

[0067] The second hydraulic assembly 108 has a further first line 130 and a further second line 132.

[0068] The further first line 130 is connected to the first working chamber 122 of the steering transmission housing 104.

[0069] Accordingly, a further second line 132 is connected to the second working chamber 124 of the steering gear housing 104.

[0070] According to the switching position diagram of the backup switching valve 128 in the Figure 1 active state, the backup switching valve is switched into a through position according to the inactive state or the fault state.

[0071] Accordingly, the first working chamber 122 and the second working chamber 124 are connected to each other via the further first line 130 and the further second line 132 and via the hydraulic filter element 126 and the backup switching valve 128.

[0072] According to the switching position diagram of the backup switching valve 128 in the Figure 1 second hydraulic assembly 108 also has a bridge circuit 134 with four outer branches 136 and a bridge branch 138, wherein the four outer branches 136 are connected to each other via four outer nodes 140.

[0073] The bridge branch 138 is formed by a series circuit of the hydraulic filter element 126 and the backup switching valve 128.

[0074] Accordingly, the first working chamber 122 and the second working chamber 124 are connected to each other via the further first line 130 and the further second line 132 and via the bridge circuit 134.

[0075] To this end, the bridge circuit 134 is connected to the further first line 130 and the further second line 132 by means of two outer nodes 140.

[0076] The bridge branch 138 is connected to two further outer nodes 140 of the bridge circuit, which are not connected to the further first line 130 and the further second line 132.

[0077] In the further first line 130 and the further second line 132, respectively, a hydraulic filter element can be arranged.

[0078] The backup switching valve 128 is configured as a two-position two-way magnetic valve and has a valve core and a magnetic coil for operating the valve core, wherein a change in the switching position of the valve core triggers an induced voltage in the magnetic coil.

[0079] Furthermore, according to the application, a utility vehicle (not shown) is provided, which has an electronic hydraulic steering system 100 as described above. Figure 1

[0080] The function of the steering system 100 according to the application will be explained below: In principle, the hydraulic pump 116 can supply the steering gear 102 with hydraulic fluid. ​

[0081] Moreover, the steering transmission 102 can be controlled due to the bidirectional configuration of the hydraulic pump 116.

[0082] In particular, the first working chamber 122 can be supplied with hydraulic fluid via the first line 118 and thus be controlled, since the first line 118 connects this working chamber 122 with the hydraulic pump 116.

[0083] Correspondingly, the second working chamber 124 can be supplied with hydraulic fluid via the second line 120 and thus be controlled, since the second line 120 connects this working chamber 124 with the hydraulic pump 116.

[0084] The control is as follows: The hydraulic pump 116 pressurizes only the first working chamber 122 or the second working chamber 124 of the steering transmission (but not both at the same time).

[0085] The hydraulic pump 116 is therefore configured to pressurize the first line 118 according to a first conveying direction and to pressurize the second line 120 according to a second conveying direction.

[0086] When the electric motor M drives the hydraulic pump 116, for example in the clockwise direction, the hydraulic pump pressurizes the first line 118 according to its first conveying direction, which extends to the first working chamber 122.

[0087] The hydraulic pump 116 and the steering transmission 102 are therefore connected to each other via the first line 118, and the interface of the steering transmission 102, which is connected to the first line 118 and leads into the first working chamber 122, is pressurized.

[0088] Subsequently, the pressure in the first working chamber 122 rises, and the piston is forced to move linearly, since the pressure in the opposing second working chamber 124 is lower, so that a steering support is achieved via the steering output shaft.

[0089] The pressure in the opposing second working chamber 124 is lower because this working chamber 124 is connected to the tank via the second line 120 and a corresponding return line (not shown in the figure). Figure 1 In this way, hydraulic oil can flow back from the second working chamber 124 into the tank.

[0090] It is important in this context to understand that the hydraulic pump 116 is always driven only in one rotational direction, so that only the first line 118 or the second line 120 can be pressurized at all times.

[0091] When the rotational direction of the hydraulic pump 116 is reversed, the above-described situation or scenario takes place in reverse order, as follows:

[0092] ​Once the electric motor M (for example counterclockwise) drives the hydraulic pump 116, the latter pressurizes the second line 120 according to a second conveying direction, which extends to the second working chamber 124.

[0093] Therefore, the hydraulic pump 116 and the steering transmission 102 are connected to each other via the second line 120, and the interface of the steering transmission 102, which is connected to the second line 120 and leads into the second working chamber 124, is pressurized.

[0094] Subsequently, in the second working chamber 124, the pressure rises, and the piston is forced to perform a linear movement, since the pressure in the opposite first working chamber 122 is lower at this time, so that a steering support is achieved via the steering output shaft.

[0095] The pressure in the opposite first working chamber 122 is thus lower, since this working chamber 122 is connected to the tank via the first line 118 and a corresponding return line (not shown in Figure 1 ).

[0096] In this way, hydraulic oil can flow back from the first working chamber 122 into the tank.

[0097] It is important in this context to understand that the hydraulic pump 116 is always driven only in one rotational direction, and thus can always only pressurize the first line 118 or the second line 120.

[0098] The function of the above-described steering system 100 is described according to a normal operating state, wherein the following function description illustrates a non-activated state or a fault state of the system: In this state, the backup switching valve 128 is arranged in the through position shown in Figure 1 .

[0099] This position achieves an uninterrupted flow path from the first working chamber 122 via the further first line 130 and the further second line 132 and via the bridge line 134 to the second working chamber 124.

[0100] The flow direction of the hydraulic oil depends on the pressure gradient between the first working chamber 122 and the second working chamber 124.

[0101] This pressure gradient can be generated only by a manual steering movement of the steering input shaft, which is shown on the left side of the second working chamber 124 in Figure 1 , wherein the steering input shaft can also be arranged in other positions.

[0102] Since the rotation of the steering shaft achieves a linear movement of the steering transmission piston via the internal spindle (in this case without pressurization of the hydraulic pump 116), wherein this case corresponds to the fault state.

[0103] Alternatively, as described above, the pressure gradient is formed by the hydraulic pump 116 selectively pressurizing the first working chamber 122 or the second working chamber 124, wherein this case corresponds to the inactive state of the steering system.

[0104] In this case, the steering system is in normal operation, and the control and / or regulating device actuates the reserve switching valve 128 into the through position.

[0105] The inactive state means that the steering system is in an inactive state, i.e. either the commercial vehicle is currently not in motion or the commercial vehicle is in motion, but no steering support is required in the future in time.

[0106] In other words, a future steering support of the steering system is not expected with a certain probability (and thus no pressurization of the steering transmission 102 is required).

[0107] In this state, the further functional configuration of the second assembly 108 in the form of filtered hydraulic oil can advantageously be utilized.

[0108] Since the hydraulic pump 116 must be operated approximately continuously, so that the driver perceives a certain steering resistance, and since the steering support can only be generated sufficiently quickly when the hydraulic pump is already running.

[0109] Therefore, in the inactive state, the pump operation can be utilized such that the hydraulic pump 116 pressurizes one of the two working chambers 122, 124, so that the pressurization must be below a pressure threshold value at which the actual steering support is triggered (this is achieved by the system inertia and friction).

[0110] Since the filter element is arranged in the reserve assembly, the hydraulic oil can be filtered with very high energy efficiency.

[0111] If there is a higher pressure in the first working chamber 122 than in the second working chamber 124, the following flow path or hydraulic oil flow is generated in the second assembly 108 through the following components: - the further first line 130 (in which the hydraulic filter, if necessary, is located); - the external node 140, which connects the bridge line 134 and the further first line 130; - the further external branch 136, which passes through in the flow direction (can be clearly determined by the non-return valve arrangement); - the bridge branch 138 with the hydraulic filter element 126 and the reserve switching valve 128; - the further external branch 136, which passes through in the flow direction (connects the bridge branch 138 with the external node 140, which connects the further second line 132); - the further second line 132; and - the second working chamber 124.

[0112] If there is a higher pressure in the second working chamber 124 than in the first working chamber 122, a flow path or rather a flow of hydraulic oil through the following components is created in the second assembly: - the further second line 132 (if necessary with a hydraulic filter element in this line); - the external node 140 connecting the bridge line 134 and the further second line 132; - the external branch 136 which runs in flow direction (clearly defined by a non-return valve arrangement); - the bridge branch 138 with the hydraulic filter element 126 and the backup switching valve 128; - the further external branch 136 which runs in flow direction (connecting the bridge branch 138 with the external node 140 connecting the further first line 130); - the further first line 130; and - the first working chamber 122.

[0113] The two flow paths described above achieve a purification of the hydraulic oil by the hydraulic filter element 126 as main filter element.

[0114] Thus, in the inactive state of the steering system 100, the hydraulic oil can be purified very efficiently, since the pressure required here is far below the pressure required for steering support, and no additional pump or valve is required here.

[0115] The pressure for the filtration must not result in the steering gear piston being operated such that it triggers an actual steering movement, so the pressure must be below a threshold value.

[0116] But due to friction and inertia in the steering system, filtration can still be achieved below the threshold value described above; thus, in the future inactive state of the steering system 100, a very efficient purification is achieved by the hydraulic filter element 126.

[0117] List of reference signs 100 electronic hydraulic steering system 102 steering gear, in particular screw steering gear 104 steering gear housing 106 first hydraulic assembly, in particular electronic hydraulic assembly 108 second hydraulic assembly, in particular electronic hydraulic assembly 110 first housing block 112 second housing block 114 electronic control and / or regulating device 116 hydraulic pump 118 first line 120 second line 122 first working chamber 124 second working chamber 126 hydraulic filter element 128 reserve switching valve 130 further first line 132 further second line 134 bridge line 136 external branch 138 bridge branch 140 external node 142 check valve 144 pressure sensor 146 filter check valve M electric motor

Claims

1. An electro-hydraulic steering system (100) for vehicles, particularly commercial vehicles, comprising: - At least one steering drive (102), especially a lead screw steering drive, with at least one steering drive housing (104). - At least one first hydraulic component (106), particularly an electro-hydraulic component, which may be fastened to the steering transmission housing (104); - At least one second hydraulic component (108), particularly an electro-hydraulic component, which may be fastened to the steering transmission housing (104); in, One or more components of the first hydraulic assembly (106) are at least partially integrated in the first housing block (110), wherein one or more components of the second hydraulic assembly (108) are at least partially integrated in the second housing block (112), or wherein one or more components of the first hydraulic assembly (106) and the second hydraulic assembly (108) are at least partially integrated in a common housing block.

2. The electro-hydraulic steering system (100) according to claim 1, characterized in that, The common housing block has a first housing block (110) and a second housing block (112).

3. The electro-hydraulic steering system (100) according to claim 1 or 2, characterized in that, The first hydraulic assembly (106) has at least one hydraulic pump (116) and at least one electric motor (M) for driving the hydraulic pump (116), through which hydraulic oil can be supplied to the steering transmission (102) and / or the steering transmission can be controlled.

4. The electro-hydraulic steering system (100) according to any one of claims 1 to 3, characterized in that, The first hydraulic assembly (106) has at least one first conduit (118) connected to at least one first working chamber (122) of the steering gear housing (104), and hydraulic oil can be supplied to and / or controlled in the first working chamber (122) through the first conduit. The first hydraulic assembly (106) also has at least one second conduit (120) connected to at least one second working chamber (124) of the steering gear housing (104), and hydraulic oil can be supplied to and / or controlled in the second working chamber (124) through the second conduit.

5. The electro-hydraulic steering system (100) according to claim 3 or 4, characterized in that, The hydraulic pump (116) is configured as a bidirectional hydraulic pump, having a first delivery direction and a second delivery direction, and is connected to the first pipeline (118) and the second pipeline (120). The hydraulic pump (116) is configured to pressurize the first pipeline (118) according to the first delivery direction and pressurize the second pipeline (120) according to the second delivery direction.

6. The electro-hydraulic steering system (100) according to any one of the preceding claims, characterized in that, The second hydraulic component (108) is configured as a backup component and is connected to the steering transmission (102) in at least one fault state and / or at least one inactive state of the steering system (100).

7. The electro-hydraulic steering system (100) according to any one of the preceding claims, characterized in that, The second hydraulic assembly (108) has at least one hydraulic filter element (126) and at least one standby switching valve (128).

8. The electro-hydraulic steering system (100) according to claim 7, characterized in that, The hydraulic filter element (126) and the backup switching valve (128) are connected in series.

9. The electro-hydraulic steering system (100) according to any one of claims 4 to 8, characterized in that, The second hydraulic assembly (108) has at least one additional first line (130) and at least one additional second line (132), wherein the additional first line (130) is connected to the first working chamber (122) of the steering gear housing (104), and wherein the additional second line (132) is connected to the second working chamber (124) of the steering gear housing (104).

10. The electro-hydraulic steering system (100) according to any one of claims 7 to 9, characterized in that, In the inactive and / or faulty state, the backup switching valve (128) is switched to the through position, such that the first working chamber (122) and the second working chamber (124) are connected at least through the additional first pipeline (130) and the additional second pipeline (132) and through the hydraulic filter element (126) and the backup switching valve (128).

11. The electro-hydraulic steering system (100) according to any one of claims 7 to 10, characterized in that, The standby switching valve (128) is configured as a two-position two-way solenoid valve and has at least one valve core and at least one magnetic coil for operating the valve core, wherein a change in the switching position of the valve core triggers an induced voltage in the magnetic coil.

12. The electro-hydraulic steering system (100) according to any one of the preceding claims, characterized in that, The second hydraulic assembly (108) has at least one bridge line (134) having four external branches (136) and one bridge branch (138), wherein the four external branches (136) are interconnected by four external nodes (140).

13. The electro-hydraulic steering system (100) according to claim 12, characterized in that, The bridge branch (138) consists of a series circuit including the hydraulic filter element (126) and the backup switching valve (128).

14. The electro-hydraulic steering system (100) according to claim 12 or 13, characterized in that, The bridge line (134) is connected to the additional first conduit (130) and the additional second conduit (132) via two external nodes (140), wherein the bridge branch (138) is connected to the two additional external nodes (140).

15. A vehicle, particularly a commercial vehicle, having at least one electro-hydraulic steering system (100) according to any one of claims 1 to 14.

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