Steering systems for vehicles, especially commercial vehicles

Abstract

The present invention relates to an electrohydraulic steering system (100) for vehicles, particularly commercial vehicles, the following: -At least one steering gear (102) having at least one steering gear housing (104), in particular a spindle-type steering gear (102), -At least one first hydraulic, in particular electro-hydraulic assembly (106) that can be fixed to the steering gear housing (104), - comprising at least one second hydraulic, in particular electro-hydraulic assembly (108) that can be fixed to the steering gear housing (104), Here, one or more components of the first hydraulic assembly (106) are integrated at least partially within the first housing block (110), and Here, one or more components of the second hydraulic assembly (108) are integrated at least partially within the second housing block (112), or The present invention relates to an electro-hydraulic steering system for a vehicle, wherein one or more components of a first hydraulic assembly (106) and a second hydraulic assembly (108) are integrated at least partially within a common housing block. Furthermore, the present invention relates to a vehicle, particularly a commercial vehicle, equipped with the steering system described above.

Description

Technical Field

[0001] The present invention relates to a vehicle, particularly an electro-hydraulic steering system for a commercial vehicle. Further, the present invention relates to a vehicle equipped with such an electro-hydraulic steering system, particularly a commercial vehicle.

[0002] In conventional steering systems for commercial vehicles, large structural space requirements are generated by hydraulic elements such as filters and valves, and / or control elements such as actuators. Such large structural space requirements have a negative impact on the output density, performance, and functional density of the steering system.

[0003] In the prior art, steering systems for vehicles, particularly for commercial vehicles, are already known.

[0004] According to this, German Patent Application Publication No. 102016112332 shows a method for monitoring a closed-loop control block that drives and controls an actuator drive unit, particularly an actuator drive unit of a steering system.

[0005] The object of the present invention is to develop an electro-hydraulic steering system of the type described at the beginning in an advantageous manner. In particular, the system may have a higher output density, may be composed more simply with fewer components and / or pipelines, and thereby be developed so that potential error causes can be eliminated.

[0006] This object is solved by an electro-hydraulic steering system having the features of claim 1 according to the present invention. According to this, an electro-hydraulic steering system for a vehicle, particularly a commercial vehicle, comprising the following: - at least one steering gear having at least one steering gear housing, particularly a spindle-type steering gear; - at least one first hydraulic, particularly electro-hydraulic assembly that can be fixed to the steering gear housing; - comprising at least one second hydraulic, in particular electro-hydraulic assembly that can be fixed to the steering gear housing, Here, one or more components of the first hydraulic assembly are integrated at least partially within the first housing block, and Here, one or more components of the second hydraulic assembly are integrated at least partially within the second housing block, or One or more components of the first hydraulic assembly and the second hydraulic assembly are integrated at least partially within a single common housing block. The aim is to provide an electro-hydraulic steering system for vehicles.

[0007] The present invention is based on the following fundamental consideration: that one or more components of a first or second hydraulic assembly may be integrated, at least partially, within the first and second housing blocks or a common housing block. This allows for very high power density with internal piping guidance within the housing block, thereby eliminating elasticity (and thus inertia) and additional sources of failure within the steering system. It may also be assumed that all components of the first and second hydraulic assemblies may be integrated, respectively, within the first and second housing blocks or a common housing block. It should be understood that this type of integration does not intend to require one or more components to be structurally and completely integrated or embedded within the housing block (for example, in the case of a switching valve, the valve plunger and certain ports may be integrated, but the control or operating area and possibly external ports may be located outside the housing block or flange-fixed to the housing block). The valve block may be configured such that the necessary bores, conduits, wall structures, etc., for one or more components are introduced into the block material, thereby forming the housing block. The common housing block may, here, contain all the components of the first and second hydraulic assemblies. However, alternatively, the common housing block may be considered to contain only some of the components of the first and second hydraulic assemblies. The common housing block may be manufactured as a block material (e.g., made of an aluminum alloy) that is manufactured as a single unit. The first and second hydraulic assemblies may also be understood as separate assemblies, in which case they differ at least in function and / or in their structural components.

[0008] Alternatively, the common housing block may have a first housing block and a second housing block. This configuration allows for a two-part configuration of the common housing block, and consequently, a variable configuration of the first and second hydraulic assemblies. The first and second housing blocks can be fastened to each other for this purpose (e.g., by screw fastening, welding, or similar appropriate methods).

[0009] Furthermore, the first hydraulic assembly may be assumed to have at least one hydraulic pump and at least one electric motor for driving the hydraulic pump, which is capable of supplying and / or controlling working fluid to the steering gear. By integrating at least partially the hydraulic pump into the first housing block, the flow path for its supply and drive control from the pump to the steering gear can be shortened, thereby enabling the steering gear to be driven, controlled and supplied with working fluid (configured, for example, as a hydraulic fluid suitable for the steering gear) more quickly, more accurately, and with less pipeline loss.

[0010] Furthermore, the first hydraulic assembly may have at least one first conduit that is connected to at least one first working chamber of the steering gear housing and to which working fluid can be supplied and / or controlled. The first hydraulic assembly may also have at least one second conduit that is connected to at least one second working chamber of the steering gear housing and to which working fluid can be supplied and / or controlled. By providing the first and second conduits inside the first or second housing block or a common housing block, the conduit length of the first or second housing block or the common housing block becomes very short, thereby allowing the steering gear to be driven, controlled and supplied by the hydraulic fluid more quickly, more accurately, and with less conduit loss. Alternatively, the first and second conduits can be introduced directly into each block (e.g., as holes, grooves, or other recesses), thereby enabling a very simple configuration of these conduits.

[0011] Alternatively, the hydraulic pump may be configured as a bidirectional hydraulic pump having first and second discharge directions, connected to a first and second pipeline, in which case the hydraulic pump is configured to pressurize the first pipeline according to the first discharge direction and the second pipeline according to the second discharge direction. A bidirectional pump is particularly advantageous for this application because the steering gear piston needs to be pressurized in various directions on both sides, at its respective end faces and the two working chambers formed therein, in order to generate steering force assistance. This is because, by reversing their rotational directions, the discharge direction of the pump changes automatically in function, and thus pressurizing the two working chambers of the steering gear can be carried out very easily via the first and second pipelines. Thus, this configuration results in a highly efficient pump configuration for appropriately adapted applications in steering gears.

[0012] Furthermore, a second hydraulic assembly may be configured as a backup assembly and connected to the steering gear in at least one error condition and / or at least one non-operational condition of the steering system. When an error condition occurs in the first hydraulic assembly, the working fluid or hydraulic oil from it can no longer flow out of or into the first or second work chamber, thereby rendering the steering gear inoperable. For this reason, a second hydraulic assembly may be provided to short-circuit the connection between the first and second work chambers (e.g., in an error condition), thereby allowing the steering gear to remain controllable and the commercial vehicle to remain safely steerable. Alternatively or additionally, the backup assembly may be driven to disconnect the connection between the two work chambers in the non-operational condition (e.g., by the open-loop control and / or closed-loop control device of the steering system), which would allow for a more efficient implementation of further functionality for the steering system in the case of the non-operational condition of the second hydraulic assembly.

[0013] In addition, the second hydraulic assembly may be envisioned to have at least one hydraulic filter element and at least one backup switching valve. The backup switching valve substantially fulfills the following function: namely, the backup switching valve is basically switchable from the shut-off position to the through position and vice versa, thereby connecting the two working chambers of the steering gear via the second assembly, thereby allowing the vehicle to still be steered. This is particularly advantageous in error conditions, because the hydraulic short circuit (made possible by the second assembly) keeps the working chambers of the steering gear connected, thereby ensuring the steering capability of the steering gear continues. In the shut-off position of the backup switching valve, the second assembly is non-functional, and control of the steering gear and supply of working fluid to the steering gear are performed via the first assembly. The integration of a hydraulic filter element into the second assembly has the advantage of giving the second assembly further functionality, particularly in non-operating conditions, specifically the filtering of the hydraulic fluid.

[0014] Furthermore, the hydraulic filter element and the backup switching valve may be envisioned to constitute a single series circuit. This circuit provides a highly efficient means of controlling the working fluid and directing it through the hydraulic filter element in the shortest possible path. This reduces the flow resistance of the steering system during the filtration of the working fluid or hydraulic oil and increases efficiency.

[0015] Furthermore, the second hydraulic assembly may be envisioned to have at least one further first conduit and at least one further second conduit. In particular, the further first conduit may be connected to a first working chamber of the steering gear housing, and the further second conduit may be connected to a second working chamber of the steering gear housing. By providing the further first and further second conduits (depending on the configuration) inside the respective housing blocks, their conduit lengths are made very short, thereby allowing the steering gear to be supplied with hydraulic fluid more quickly, more accurately, and with less conduit loss in error or non-operating conditions. Also, the further first and further second conduits can be introduced directly into the respective blocks (e.g., as holes, grooves, or other recesses), thereby enabling a very simple configuration of these conduits.

[0016] Furthermore, the backup switching valve is switched to the pass position in non-operating and / or error states, thereby it is conceivable that the first and second work chambers are connected at least via further first and further second piping, as well as via the hydraulic filter element and the backup switching valve. The first state relates to an error state, for example, where the flow supply fails, followed by a return spring switching the backup switching valve to the pass position, thereby connecting the two work chambers of the steering gear, and thereby the vehicle is still steerable. The second function or second state relates to a non-operating state in which no further steering assistance (and consequently the depressurization of the steering gear) of the steering system can be anticipated. In this state, further functional loads of the second assembly (specifically, filtration of the hydraulic fluid) can be advantageously utilized, because the hydraulic pump needs to be operating continuously so that the driver can feel a certain steering resistance sensation, because steering force assistance can only be generated quickly enough when the hydraulic pump is already operating. Therefore, the pump operation in the non-operating state can be utilized to pressurize one of the two working chambers, but the pressurization must be below a pressure threshold (possible due to system inertia and friction) such that actual steering assistance is not initiated. In this case, the hydraulic fluid flows from the pressurized working chamber through the backup assembly to the unpressurized working chamber of the steering gear, and vice versa for the opposite pressurization. Since the filter element is located within the backup assembly, the hydraulic fluid can be filtered very energy-efficiently.

[0017] Furthermore, the backup switching valve may be configured as a 2-port, 2-way solenoid valve, which may have at least one switching plunger and at least one electromagnetic coil for operating the switching plunger. In this case, a change in the switching position of the switching plunger can trigger an induced voltage in the electromagnetic coil. For the safety of the system, this switching position is an important monitoring variable or important monitoring parameter that should always be accurately monitored. The plunger position can be monitored very easily because a coil current is generated via the induced voltage in the electromagnetic coil, which is seizureable. Also, a 2-port, 2-way solenoid valve is a simply configured valve with a correspondingly reduced error or failure probability, which positively contributes to system safety.

[0018] In addition, the second hydraulic assembly may include at least one bridge circuit having four external branches and one bridge branch, in which case the four external branches may be interconnected via four external nodes. This type of bridge circuit allows unidirectional flow through the hydraulic filter element, even though the direction of flow within the further first and further second conduits changes in accordance with the pressurization in the two working chambers of the steering gear housing (see description above). This makes the hydraulic filter element easier to configure because it always flows in only one defined direction.

[0019] Furthermore, the bridge branch may be assumed to consist of a series circuit including a hydraulic filter element and a backup switching valve. This configuration of the bridge branch allows for unidirectional flow through the hydraulic filter element, which has the advantages described in the preceding paragraph.

[0020] Also, the bridge circuit is connected to a further first pipeline and a further second pipeline using a second external node, and in this case, it is conceivable that the bridge branch is connected to two further external nodes. This interconnection results in a symmetrical connection or interconnection with the further first and further second pipelines and the bridge branch, whereby the pipeline lengths are identical in two flow paths or flow directions, and thereby, the same control characteristics occur between two opposite movements of the control piston of the steering gear (e.g., in an error state).

[0021] Furthermore, according to the present invention, a vehicle, particularly a commercial vehicle, equipped with at least one electrohydraulic steering system as described above is envisaged. All advantages and technical effects that can be obtained in relation to the steering system according to the present invention can be applied to the vehicle according to the present invention individually or in combination. This vehicle may particularly be a commercial vehicle.

[0022] Further details and advantages of the present invention will be explained in more detail herein based on the embodiments shown in the drawings.

Brief Description of the Drawings

[0023] [Figure 1] It is a schematic diagram showing a switching arrangement configuration of an embodiment of a steering system according to the present invention.

[0024] FIG. 1 shows a schematic diagram of a switching arrangement configuration of an embodiment of a steering system 100 according to the present invention.

[0025] The electrohydraulic steering system 100 for a commercial vehicle has a steering gear 102 in the form of a spindle type steering gear 102, and this steering gear 102 also has a steering gear housing 104.

[0026] The spindle type steering gear 102 may be configured as a ball circulation type spindle type steering gear, and in this case, other gear forms are also conceivable.

[0027] The electro - hydraulic steering system 100 further includes a first hydraulic assembly 106, and this first hydraulic assembly 106 is fixed to the steering gear housing 104.

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

[0029] Also, the electro - hydraulic steering system 100 has a second hydraulic assembly 108 fixed to the steering gear housing 104.

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

[0031] Fixing the first and second hydraulic assemblies 106, 108 to the steering gear housing 104 can be achieved through corresponding flange joints, but these flange joints are not shown in the schematic diagram of FIG. 1.

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

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

[0034] According to FIG. 1, the first and second housing blocks 110, 112 are configured as structurally separate blocks and are fixed at various locations of the steering gear housing 104.

[0035] For example, the first and second housing blocks 110, 112 may be fixed at opposing locations (i.e., in an orientation of 180° relative to each other) on the steering gear housing 104.

[0036] Similarly, the first and second housing blocks 110 and 112 may be fixed in the steering gear housing 104 at an orientation of 90° or 270° relative to each other.

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

[0038] A common housing block may have a first housing block 110 and a second housing block 112, or may consist of these two blocks 110, 112, or alternatively may be configured as a single, integrated housing block (made of the same material as the entire block).

[0039] In addition, the steering system 100 has an electronic open-loop control and / or closed-loop control device 114 for open-loop control and / or closed-loop control of the first and second hydraulic assemblies 106, 108.

[0040] As a component, the first hydraulic assembly 106 includes a hydraulic pump 116 and an electric motor M for driving the hydraulic pump 116.

[0041] The hydraulic pump 116 is configured as a double-acting or bidirectional hydraulic pump having a first and a second discharge direction.

[0042] The first hydraulic assembly 106 further includes a first conduit 118 connected to a first working chamber 122 of the steering gear housing 104.

[0043] Accordingly, the first hydraulic assembly 106 also includes a second conduit 120 connected to a second working chamber 124 of the steering gear housing 104.

[0044] As can be seen in Figure 1, the hydraulic pump 116 is connected to the first pipeline 118 and the second pipeline 120.

[0045] Alternatively, instead of the above configuration, a single, simple-to-operate hydraulic pump may be provided, connected to the first and second pipelines 118 and 120 via a corresponding switching valve (not shown in Figure 1), and this hydraulic pump may be connected to the first and second pipelines 118 and 120 according to the switching logic.

[0046] Alternatively, two hydraulic pumps may be provided, in which case each pump may be assigned to or connected to either the first or second pipeline 118,120.

[0047] According to Figure 1, the first conduit 118 extends from the first pressure output side of the hydraulic pump 116 to a port of the steering gear housing 104 that opens into the first working chamber 122.

[0048] The second conduit 120 extends from the second pressure output side of the hydraulic pump 116 to a port in the steering gear housing 104 that opens into the second working chamber 124.

[0049] One hydraulic filter element may be placed in each of the first pipeline 118 and the second pipeline 120.

[0050] Furthermore, as shown in Figure 1, a pressure sensor is located within the first pipeline 118.

[0051] Furthermore, a pressure sensor and a temperature sensor are located inside the second pipeline 120.

[0052] Additionally or alternatively, a temperature sensor may be located within the first conduit 118.

[0053] The first hydraulic assembly 106 may further have a hydraulic tank that is fully or partially integrated within the first housing block 110.

[0054] Alternatively, the hydraulic tank may be flange-fixed to the first housing block 110.

[0055] The hydraulic tank is only shown schematically based on Figure 1, and therefore it is possible that the hydraulic pump 116 is integrated into the tank.

[0056] Alternatively or additionally, the electric motor, hydraulic tank, and hydraulic pump 116 may be flange-fixed to each other and connected via appropriate piping (not shown in Figure 1).

[0057] The hydraulic tank is further equipped with pressure and temperature sensors to monitor the pressure and temperature of the hydraulic fluid inside the tank.

[0058] The second hydraulic assembly 108 is configured as a backup assembly and is connected to the steering gear 102 in the event of an error in the steering system 100.

[0059] Alternatively or additionally, the second hydraulic assembly 108 may be connected to the steering gear 102 when the steering system 100 is inactive.

[0060] Here, "connection" can generally be understood to mean that a continuous flow path is provided between the steering gear working chambers 122 and 124 via the second hydraulic assembly 108.

[0061] The second hydraulic assembly 108 has, among other components, a hydraulic filter element 126 and a backup switching valve 128.

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

[0063] The hydraulic filter element 126 is located upstream of 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 may be arranged in parallel with the hydraulic filter element 126.

[0065] The pressure sensor 144 may be configured as a differential pressure sensor, or alternatively, as two separate pressure sensors or pressure switches having configurable trigger thresholds (not shown in Figure 1).

[0066] The aforementioned pressure sensor 144, the additional sensors of the aforementioned first hydraulic assembly 106, and the electric motor M are connected to the electronic open-loop control and / or closed-loop control device 114 via corresponding conduits (not shown in Figure 1).

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

[0068] A further first conduit 130 is connected to the first working chamber 122 of the steering gear housing 104.

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

[0070] According to the depiction of the switching position of the backup switching valve 128 in Figure 1, the backup switching valve 128 is switched to the pass position according to the non-operating state or error state.

[0071] Therefore, the first work chamber 122 and the second work chamber 124 are connected via further first and further second conduits 130, 132, as well as via the hydraulic filter element 126 and the backup switching valve 128.

[0072] Furthermore, the second hydraulic assembly 108, as shown in Figure 1, comprises a bridge circuit 134 having four external branches 136 and one bridge branch 138, in which case the four external branches 136 are interconnected via four external nodes 140.

[0073] The bridge branch 138 is also composed of a series circuit consisting of a hydraulic filter element 126 and a backup switching valve 128.

[0074] Therefore, the first work chamber 122 and the second work chamber 124 are connected to each other via further first and further second conduits 130, 132, and via the bridge circuit 234.

[0075] For this purpose, the bridge circuit 134 is connected to a further first conduit 130 and a further second conduit 132 using a second external node 140.

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

[0077] A hydraulic filter element may be placed in each of the further first and further second conduits 130 and 132.

[0078] The backup switching valve is configured as a 2-port, 2-way solenoid valve and has a switching plunger and an electromagnetic coil for operating the switching plunger. In this case, a change in the switching position of the switching plunger triggers an induced voltage in the electromagnetic coil.

[0079] Furthermore, according to the present invention, a commercial vehicle is envisioned that is equipped with the electro-hydraulic steering system 100 described above (although not shown in Figure 1).

[0080] The functions of the steering system 100 according to the present invention can be described as follows.

[0081] The hydraulic pump 116 essentially supplies working fluid to the steering gear 102.

[0082] Furthermore, the steering gear 102 can be controlled based on its bidirectional configuration with respect to the hydraulic pump 116.

[0083] More precisely, the first working chamber 122 can be supplied with and controlled by the first conduit 118, because the first conduit 118 connects the working chamber 122 to the hydraulic pump 116.

[0084] Accordingly, the second working chamber 124 can be supplied with and controlled by the second conduit 120, because the second conduit 120 connects the working chamber 124 to the hydraulic pump 116.

[0085] This control is achieved by pressurizing either the first working chamber 122 or the second working chamber 124 of the steering gear by the hydraulic pump 116 (but not both simultaneously).

[0086] Therefore, the hydraulic pump 116 is configured such that the first pipeline 118 is pressurized according to the first discharge direction, and the second pipeline 120 is pressurized according to the second discharge direction.

[0087] As soon as the hydraulic pump 116 is driven by the electric motor M (for example, clockwise), the hydraulic pump 116 pressurizes the first pipeline 118, which extends to the first working chamber 122, according to its first discharge direction.

[0088] Therefore, the hydraulic pump 116 and the steering gear 102 are connected to each other via the first conduit 118, and the port of the steering gear 102 that is connected to the first conduit 118 and opens to the first work chamber 122 is pressurized.

[0089] Accordingly, the pressure increases in the first working chamber 122, forcing the piston to shift linearly. This is because a lower pressure prevails in the opposing second working chamber 124, thereby achieving steering assistance via the steering output shaft.

[0090] Therefore, the pressure in the opposing second working chamber 124 is lower because this working chamber 124 is connected to the tank via the second pipeline 120 and (not shown in Figure 1) a corresponding return pipeline.

[0091] Therefore, the hydraulic fluid can flow back into the tank from the second working chamber 124.

[0092] In this regard, it is important to understand that the hydraulic pump 116 is always driven in only one direction of rotation, and therefore only the first or second pipeline 118, 120 can always be pressurized.

[0093] When the rotation direction of the hydraulic pump 116 is reversed, the above-described relationships or cases proceed in exactly the reverse order, as described below.

[0094] As soon as the hydraulic pump 116 is driven by the electric motor M (for example, counterclockwise), the hydraulic pump 116 pressurizes the second pipeline 120, which extends to the second working chamber 124, according to the second discharge direction.

[0095] Therefore, the hydraulic pump 116 and the steering gear 102 are interconnected via a second conduit 120, and the port of the steering gear 102, which is connected to the second conduit 120 and opens into the second work chamber 124, is pressurized.

[0096] Accordingly, the pressure in the second working chamber 124 increases, forcing the piston to make a linear shift movement. This is because a lower pressure prevails in the opposing first working chamber 122, thereby achieving steering assistance via the steering output shaft.

[0097] Therefore, the pressure in the opposing first working chamber 122 is lower because this working chamber 122 is connected to the tank via the first pipeline 118 and (not shown in Figure 1) a corresponding return pipeline.

[0098] Therefore, the hydraulic fluid can flow back into the tank from the first working chamber 122.

[0099] In this regard, it is important to understand that the hydraulic pump 116 is always driven in only one direction of rotation, and therefore only the first or second pipeline 118, 120 can always be pressurized.

[0100] The functions of the steering system 100 described above are explained according to the normal operating state, while the following function descriptions describe the system's non-operational or error state.

[0101] In this state, the backup switching valve 128 is positioned in the flow switching position shown in Figure 1.

[0102] This position allows for uninterrupted flow from the first work chamber 122 to the second work chamber 124 via further first and second conduits 130, 132 and bridge circuit 134.

[0103] The direction of flow of the hydraulic fluid depends on the pressure gradient between the first working chamber 122 and the second working chamber 124.

[0104] The pressure gradient can only be generated by manual steering movement of the steering input shaft, which is shown to the left of the second working chamber 124 in Figure 1, in which case the steering input shaft may be located in a different position.

[0105] This is because the rotation of the steering shaft takes into account the linear shift movement of the steering gear piston via the internal spindle (in this case, no pressurization is performed by the hydraulic pump 116), and in this case, this case is assigned to an error state.

[0106] Alternatively, the pressure gradient can be formed by selective pressurization of the first or second working chambers 122,124 by the hydraulic pump 116, as described above, in which case this case is assigned to the non-operating state of the steering system.

[0107] In this case, since the steering system is operating normally, the backup switching valve 128 is driven and controlled by the open-loop control and / or closed-loop control device, thereby switching to the pass position.

[0108] Non-operational status refers to a state where the steering system is not functioning, that is, a commercial vehicle is currently stationary or is moving but will not require steering assistance in the future in terms of time series.

[0109] In other words, the future steering assistance of the steering system (and consequently, the non-pressurization of the steering gear 102) cannot be estimated with a specific probability.

[0110] In this state, further functional assignments of the second assembly 108 in the form of hydraulic fluid filtration can be advantageously utilized.

[0111] This is because the hydraulic pump 116 needs to be operating almost continuously so that the driver can feel a certain steering resistance sensation, because steering force assistance can only be generated quickly enough if the hydraulic pump is already operating.

[0112] Therefore, the pump operation in a non-operating state can be utilized to pressurize one of the two working chambers 122, 124, but the pressurization must be below a pressure threshold (possible due to the system's inertia and friction) such that actual steering assistance is not initiated.

[0113] Since the filter element is located within the backup assembly, the hydraulic fluid can be filtered very energy-efficiently.

[0114] If the pressure inside the first working chamber 122 is higher than that inside the second working chamber 124, then, based on that, in the flow path following the second assembly 108, or in the following components: - A further first pipeline 130 (and possibly a hydraulic filter within the pipeline), - External node 140 connecting bridge circuit 134 and further first conduit 130, - An external branch 136 that is permeable in the direction of flow (uniquely determined by the arrangement of the check valve), - A bridge branch 138 equipped with a hydraulic filter element 126 and a backup switching valve 128, -A further external branch 136, which is permeable in the direction of flow, connects a bridge branch 138 to an external node 140 connected to a second conduit 132, -A further second conduit 132, and - Second working chamber 124, A flow of hydraulic fluid occurs through this passage.

[0115] If the pressure inside the second working chamber 124 is higher than that inside the first working chamber 122, then, based on that, in the flow path following the second assembly 108, or in the following components: - A further second pipeline 132 (and possibly a hydraulic filter within that pipeline), - External node 140 connecting bridge circuit 134 to a further second conduit 132, - An external branch 136 that is permeable in the direction of flow (uniquely determined by the arrangement of the check valve), - A bridge branch 138 equipped with a hydraulic filter element 126 and a backup switching valve 128, -A further external branch 136, which is permeable in the direction of flow, connects a bridge branch 138 to an external node 140 connected to a further first conduit 130, - Further first conduit 130, and - First working chamber 122, A flow of hydraulic fluid occurs through this passage.

[0116] The two aforementioned flow paths enable the cleaning of the hydraulic fluid via the hydraulic filter element 126, which is the main filter element.

[0117] To that extent, the hydraulic fluid can be cleaned very efficiently when the steering system 100 is not in operation. This is because the pressure required for this is far less than the pressure required for steering assistance, and therefore no additional pumps or valves are needed.

[0118] This filtering pressure must remain below a pressure threshold, so as not to lead to any operation that would cause the steering gear piston to trigger actual steering movement.

[0119] However, since cleaning below the aforementioned threshold is quite possible based on friction and inertia within the steering system, highly efficient cleaning via the hydraulic filter element 126 will be possible when the steering system 100 is not in operation, as is anticipated. [Explanation of Symbols]

[0120] 100 Electro-hydraulic steering system 102 Steering gears, especially spindle-type steering gears 104 Steering gear housing 106 First hydraulic, especially electro-hydraulic assembly 108 Second hydraulic, especially electro-hydraulic assembly 110 First Housing Block 112 Second Housing Block 114 Electronic open-loop control and / or closed-loop control device 116 Hydraulic pump 118 First pipeline 120 Second pipeline 122 First working chamber 124 Second working chamber 126 Hydraulic filter element 128 Backup switching valve 130 Further First Pipeline 132 A second pipeline 134 Bridge Circuit 136 External branch 138 Bridge Branch 140 external nodes 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, At least one steering gear (102), in particular a spindle-type steering gear (104), having at least one steering gear housing (104), At least one first hydraulic, in particular electro-hydraulic assembly (106) that can be fixed to the steering gear housing (104), The steering gear housing (104) comprises at least one second hydraulic, in particular electro-hydraulic assembly (108) that can be fixed to the steering gear housing (104), One or more components of the first hydraulic assembly (106) are at least partially integrated within the first housing block (110), and One or more components of the second hydraulic assembly (108) are at least partially integrated within the second housing block (112), or An electrohydraulic steering system (100) in which one or more components of the first hydraulic assembly (106) and the second hydraulic assembly (108) are integrated at least partially within a single common housing block.

2. The electrohydraulic steering system (100) according to claim 1, wherein the common housing block comprises the first housing block (110) and the second housing block (112).

3. The electro-hydraulic steering system (100) according to claim 1 or 2, wherein the first hydraulic assembly (106) comprises at least one hydraulic pump (116) and at least one electric motor (M) for driving the hydraulic pump (116) which is capable of supplying and / or controlling working fluid to the steering gear (102).

4. The electrohydraulic steering system (100) according to any one of claims 1 to 3, wherein 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 capable of supplying and / or controlling working fluid to the first working chamber (122), and further the first hydraulic assembly (106) has at least one second conduit (120) connected to at least one second working chamber (124) of the steering gear housing (104) and capable of supplying and / or controlling working fluid to the second working chamber (124).

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

6. The electrohydraulic steering system (100) according to any one of claims 1 to 5, wherein the second hydraulic assembly (108) is configured as a backup assembly and is connected to the steering gear (102) in at least one error state and / or at least one non-operation state of the steering system (100).

7. The electro-hydraulic steering system (100) according to any one of claims 1 to 6, wherein the second hydraulic assembly (108) comprises at least one hydraulic filter element (126) and at least one backup switching valve (128).

8. The electro-hydraulic steering system (100) according to claim 7, wherein the hydraulic filter element (126) and the backup switching valve (128) constitute a series circuit.

9. The electrohydraulic steering system (100) according to any one of claims 4 to 8, wherein the second hydraulic assembly (108) has at least one further first conduit (130) and at least one further second conduit (132), the further first conduit (130) being connected to the first working chamber (122) of the steering gear housing (104), and the further second conduit (132) being connected to the second working chamber (124) of the steering gear housing (104).

10. The electrohydraulic steering system (100) according to any one of claims 7 to 9, wherein the backup switching valve (128) is switched to a pass position in the non-operating state and / or the error state, thereby connecting the first working chamber (122) and the second working chamber (124) at least via the further first and further second piping (130, 132), and via the hydraulic filter element (126) and the backup switching valve (128).

11. The backup switching valve (128) is configured as a two-port, two-way solenoid valve and has at least one switching plunger and at least one electromagnetic coil for operating the switching plunger, and a change in the switching position of the switching plunger triggers an induced voltage in the electromagnetic coil, the electrohydraulic steering system (100) according to any one of claims 7 to 10.

12. The electrohydraulic steering system (100) according to any one of claims 1 to 11, wherein the second hydraulic assembly (108) comprises at least one bridge circuit (134) having four external branches (136) and one bridge branch (138), the four external branches (136) being interconnected via four external nodes (140).

13. The electrohydraulic steering system (100) according to claim 12, wherein the bridge branch (138) is configured by a series circuit including the hydraulic filter element (126) and the backup switching valve (128).

14. The electrohydraulic steering system (100) according to claim 12 or 13, wherein the bridge circuit (134) is connected to the further first conduit (130) and the further second conduit (132) using a second external node (140), and the bridge branch (138) is connected to two further external nodes (140).

15. A vehicle, particularly a commercial vehicle, comprising at least one electrohydraulic steering system (100) according to any one of claims 1 to 14.

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