Electrohydraulic steering system

Abstract

The invention relates to an electrohydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) for a vehicle, in particular a utility vehicle, having: at least one steering gear (102), in particular a screw-and-nut steering gear; at least one first line (104) and at least one second line (106), by means of which the steering gear (102) can be supplied with hydraulic fluid and / or controlled; and at least one valve device (108), in particular a low-pressure valve device, connected or connectable to the first line (104) and / or the second line (106), for reducing pressure in the first line (104) and / or the second line (106), wherein the valve device (108) can be actuated, in particular electromagnetically actuated, as required. The invention also relates to a vehicle, in particular a utility vehicle, having such an electrohydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200).

Description

[0001] DESCRIPTION

[0002] Electro-hydraulic steering system

[0003] The present invention relates to an electro-hydraulic steering system for a vehicle, in particular a commercial vehicle.

[0004] Furthermore, the present invention relates to a vehicle, in particular a commercial vehicle, with such an electro-hydraulic steering system.

[0005] Electro-hydraulic steering systems are generally known in the art. However, it has been shown that during rapid steering maneuvers, such as quick evasive maneuvers, a vehicle with such an electro-hydraulic steering system can experience a drop or decrease in operating pressure in the piston chamber of the steering system, particularly at low temperatures. This operating behavior can slow down an electro-hydraulic steering system and / or impair steering behavior in general.

[0006] Therefore, under certain circumstances, a driver might not receive the necessary hydraulic power steering assistance from the steering system in time. Furthermore, this operating behavior could negatively affect a driver's steering feel.

[0007] It is therefore an object of the present invention to provide an electro-hydraulic steering system for a vehicle, in particular a commercial vehicle, in a cost-effective, efficient and low-maintenance manner with improved system dynamics and / or system response, preferably also achieving an optimized installation space and a reduced weight of the steering system. Furthermore, it is an object of the invention to provide a vehicle with such an electro-hydraulic steering system. This object is achieved according to the invention by an electro-hydraulic steering system for a vehicle, in particular a commercial vehicle, with the features of claim 1 and a vehicle with the features of claim 15.

[0008] It may be provided in particular that an electro-hydraulic steering system for a vehicle, especially a commercial vehicle, comprises the following: at least one steering gear, in particular a screw steering gear; at least one first line through which the steering gear can be supplied with hydraulic fluid and / or controlled; at least one second line through which the steering gear can be supplied with hydraulic fluid and / or controlled; and at least one valve device, in particular a low-pressure valve device, connected or connectable to the first line and / or the second line for pressure reduction in the first line and / or the second line, wherein the valve device can be actuated as required, in particular electromagnetically actuated.

[0009] The invention is based in particular on the fundamental concept of enabling a rapid pressure relief phase in a pressure chamber of the steering gear by means of a valve assembly. In this context, it can be provided, in particular, to utilize at least a portion of the steering system's pressure or system pressure as needed to enable a pressure reduction or pressure decrease in a relevant (low-)pressure chamber of the steering gear via the first and / or second line and the valve assembly, which is at least partially actively acting or controllable. This allows for a rapid pressure relief phase in the aforementioned (low-)pressure chamber and consequently accelerates the response of the entire steering system.

[0010] In accordance with the present invention, a preferred embodiment of the steering system, and in particular of the valve assembly, with at least one electromagnet, allows for at least partial control and / or regulation, enabling a space-saving, weight-optimized, and cost-effective design. For example, a pressure chamber of the steering gear can be connected to a hydraulic tank of the steering system via the first and / or second line and the valve assembly to enable the pressure relief phase and, consequently, the responsiveness. This can further result in improved steering performance, allowing the driver to receive situationally required steering assistance from the system in a timely manner.

[0011] In other words, reducing or decreasing pressure can improve the steering feel for the driver, and system dynamics or system response can be accelerated or accelerated.

[0012] By making the valve assembly electromagnetically actuated and / or allowing its actuation to be electromagnetically controlled or supported, thus enabling at least partial electromagnetic actuation, the valve assembly can be operated in a robust and / or reliable manner. In particular, the electromagnetically actuated valve assembly can provide increased response accuracy and thus improve the system response of the steering system.

[0013] It may be provided that the steering system has at least one hydraulic tank and at least one return line which is connected or connectable to the valve assembly and the hydraulic tank.

[0014] This provides a simple structure, starting from the valve assembly, particularly for handling and returning the hydraulic fluid. Consequently, the hydraulic fluid (e.g., hydraulic oil adapted for steering gears) can flow from the first or second line (depending on the piston's direction of movement in the steering gear) via the valve assembly into the return line and then back to the hydraulic tank. In this way, a (low-)pressure chamber of the steering gear can be connected to the hydraulic tank via the first or second line, the valve assembly, and the return line. In particular, the hydraulic fluid can be quickly returned to the hydraulic tank during pressure release in the relevant (low-)pressure chamber.

[0015] Furthermore, it may be provided that the steering system has at least one check valve which is located in and / or on the return line.

[0016] In a sense, this can be considered a return line check valve. This can advantageously minimize leakage losses, particularly with regard to the valve assembly. Preferably, reduced maintenance requirements for the steering system can be achieved. Furthermore, the check valve can provide a protective function, especially for the valve assembly.

[0017] It may be provided that the first line and / or the second line can be connected to the return line by means of the valve assembly, depending on a pressure difference between the first line and / or the second line. Additionally, it may be provided that the valve assembly can be controlled electromagnetically, depending on a pressure difference between the first line and / or the second line, for example by means of a control unit.

[0018] In particular, within the meaning of the present invention, the ability to connect the first and / or second line to the return line depending on a pressure difference can be understood to mean that such an adjustment or actuation of the valve device can be carried out, for example, by switching off or de-energizing or switching an electromagnet or an actuator of a different design.

[0019] By connecting the first line preferably to a first pressure chamber of the steering gear and the second line preferably to a second pressure chamber of the steering gear, the low-pressure chamber can be connected to the hydraulic tank by means of the valve assembly during a rapid change of steering direction, based on the pressure differential prevailing between the lines. This allows the hydraulic fluid to be quickly returned to the hydraulic tank for rapid pressure reduction in the respective pressure chamber. Furthermore, pressure can be built up quickly in the other pressure chamber, thus advantageously ensuring a high steering speed and / or steering change speed for the driver.

[0020] Furthermore, it may be provided that the first line can be connected to or is connected to the return line by means of the valve device if the pressure in the second line is higher than the pressure in the first line, and / or the second line can be connected to or is connected to the return line by means of the valve device if the pressure in the first line is higher than the pressure in the second line.

[0021] An operating pressure in the first or second line (and thus in the first or second pressure chamber), which can initiate and / or assist a displacement movement of the steering gear piston, can be understood and used in this sense as a control pressure for the valve assembly. Since the piston displacement direction also changes depending on the steering direction, the control / pressure of the steering gear via the first or second line can change accordingly. As soon as the first or second line is pressurized, this pressure can be tapped or detected and fed to the valve assembly, so that, in response, the pressure in the other line can be quickly reduced via the valve assembly towards the hydraulic tank. Furthermore, this process can be assisted, for example, by electromagnetic actuation of the valve assembly.at least partially and / or completely, so that faster and safer pressure relief can be provided.

[0022] Furthermore, it may be provided that the valve device has at least one electromagnet and that switching between the first line and the second line for pressure reduction in one of the lines is electromagnetically controlled or controllable, or at least partially controlled or controllable.

[0023] This allows the valve assembly to be actuated in a robust, targeted, and / or reliable manner. In particular, the electromagnetically actuated valve assembly can thus enable increased response accuracy. The valve assembly may be provided with at least one spring element and at least one switching element, which is arranged, in particular between the spring element and the electromagnet, such that a magnetic force from the at least one electromagnet opposes the at least one spring element for adjusting, controlling, or operating the at least one switching element.

[0024] For example, the spring element can be designed to be passive. The design of the valve assembly allows for a simple and robust construction requiring minimal installation space. This can, for instance, enable simple, cost-effective, and efficient manufacturing, assembly, and / or maintenance of the valve assembly. Advantageously, since only one spring element is required, or a second spring element is unnecessary, a reliable valve assembly design can be ensured.

[0025] Furthermore, since an actuator in the form of an electromagnet only works against the spring force of the spring element, operation or corresponding actuation can also be carried out with low electrical currents in order to control the valve device.

[0026] Furthermore, it may be provided that the first line and / or the second line can be connected to the return line by means of the switching element and / or can be locked with respect to the return line.

[0027] This design can have the advantage that the connection function is preferably performed reciprocally only by the switching element, thus reducing the failure probability typically associated with a large number of different components and increasing the reliability of the steering system. Furthermore, this allows the steering system to achieve increased functionality with a simple design. A structurally very simple and cost-effective design can be provided for the functionality of switching between the lines for pressure relief. It can be provided that the switching element can be moved into a first switching position by means of the spring element, in which the first or second line is connected.with respect to the return line, and / or the switching element can be moved by means of the electromagnet, in particular against a spring force of the spring element, into a second switching position in which the second line or the first line is connected with or with respect to the return line.

[0028] This allows the switching element to be moved reliably and easily into the respective switching position and held securely there. In a sense, this can also provide a protective or safety function.

[0029] Advantageously, since the electromagnet only works against the spring force of the spring element, operation or corresponding actuation of the switching element between the aforementioned positions can also be carried out with low electrical currents in order to actuate the valve device.

[0030] It can be provided that the first and second switching positions of the switching element correspond to, and / or are defined by, a respective stop provided in the valve assembly. Thus, the first and second switching positions of the switching element can be structurally predetermined and / or definable, for example, by means of a housing body of the valve assembly and / or an additional body that can be attached to it. Different switching positions can be reliably and reproducibly assumed by the switching element, i.e., with improved repeatability.

[0031] For example, the switching element may be designed as a sliding element and / or may have one. This design can advantageously be cost-effective and easy to maintain and manufacture.

[0032] Alternatively, the switching element may be designed as a piston element and / or include one. This design can advantageously be cost-effective and easy to maintain and manufacture. The steering system may also include a backup device, in particular a backup valve device, for example a backup valve, by means of which the first and second lines can be connected directly or indirectly (to each other), in particular short-circuited.

[0033] The backup device can, for example, be indirectly connected to the first and / or second line via a pressure chamber of the steering gear assigned to the first and / or second line, and / or be directly connected to the first and / or second line.

[0034] The backup device can be opened fluidically and / or fully closed fluidically and / or be suitably designed. By providing the backup device, the safety and / or reliability of the steering system can be advantageously further improved, since the two lines, and thus also the pressure chambers of the steering gear, can be connected or short-circuited in an emergency situation, thereby ensuring appropriate pressure relief at all times. In a sense, the backup device can form and / or enable a fault circuit and / or function as such.

[0035] Preferably, the backup device can be designed as a separate or independent unit or integrated into the valve assembly. This facilitates easier maintenance of the backup device and / or saves installation space.

[0036] It may be provided that at least one first check valve is arranged in the first line and / or at least one second check valve is arranged in the second line. In this way, an additional protective function for the first and / or the second line can be enabled and provided.

[0037] It may also be provided that the steering system has at least one hydraulic pump which can be connected to or is connected to the first line and the second line and which can be connected to or is connected to at least one hydraulic tank on the suction side via a suction line.

[0038] The hydraulic pump can preferably be designed as a double-acting hydraulic pump, so that depending on the direction of rotation either the first line or the second line is pressurized. Alternatively, it is also conceivable that only a single-acting hydraulic pump is provided and connected to the first and second lines via a corresponding additional switching valve, which connects the hydraulic pump to the first or the second line depending on the switching logic.

[0039] Alternatively, it is also conceivable that two hydraulic pumps could be provided, with one pump each assigned to or connected with the first and second lines.

[0040] It may be provided that the first check valve is located in the first line and / or the second check valve is located in the second line between the hydraulic pump and the at least one hydraulic tank.

[0041] Preferably, the hydraulic pump can be connected to the hydraulic tank via at least the first and / or second check valve. The first and / or second check valve can, in particular, serve and / or function as priming valves. Advantageously, pressure build-up, especially pressure build-up controllable or controlled via a control unit associated with or assigned to the steering system, can thus occur under the influence, preferably with the support, of the priming valves. In other words, the priming valves, i.e., the first and / or second check valve, can support the hydraulic pump during pressure build-up, in particular by providing (as needed) a supply of hydraulic fluid from the hydraulic tank.

[0042] The steering system may be designed to include a filter unit located in and / or on the return line. This arrangement has the advantage that the filter does not need to be located on the high-pressure side, but rather on the low-pressure side in the return line to the hydraulic tank. Consequently, the filter can be mechanically less robust and structurally simpler, as it is not subjected to such high pressures. Cost advantages can also be achieved through this type of filter design.

[0043] Furthermore, the present invention relates to a vehicle, in particular a commercial vehicle, which has an electro-hydraulic steering system configured according to the preceding and / or following description.

[0044] All structural and functional features related to the steering system described above and its possible embodiments can also be provided in the vehicle according to the invention, either alone or in combination, and the associated advantages can be achieved accordingly.

[0045] Further details and advantages of the invention will now be explained in more detail with reference to the exemplary embodiments shown in the drawings.

[0046] They show schematically:

[0047] Fig. 1 shows a schematic representation of a circuit arrangement of an embodiment of a steering system;

[0048] Fig. 2 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0049] Fig. 3 shows a schematic sectional view of an embodiment of a valve assembly of a steering system;

[0050] Fig. 4 shows an example switching state of the valve device according to Fig. 3; Fig. 5 shows a schematic representation of a circuit arrangement of a further

[0051] Exemplary embodiment of a steering system;

[0052] Fig. 6 shows a schematic representation of a circuit arrangement of another

[0053] Exemplary embodiment of a steering system;

[0054] Fig. 7 shows a schematic representation of a circuit arrangement of another embodiment of a steering system;

[0055] Fig. 8 shows a schematic representation of a circuit arrangement of another

[0056] Exemplary embodiment of a steering system;

[0057] Fig. 9 shows a schematic sectional view of another embodiment of a valve assembly of a steering system;

[0058] Fig. 10 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0059] Fig. 11 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system; and

[0060] Fig. 12 shows a schematic representation of a circuit arrangement of another embodiment of a steering system.

[0061] Identical or functionally equivalent elements are provided with the same reference symbols in all figures.

[0062] Fig. 1 shows a schematic representation of a circuit arrangement of an embodiment of a steering system 100.

[0063] The electro-hydraulic steering system 100 for a commercial vehicle has a steering gear 102 in the form of a screw steering gear 102. The screw steering gear 102 can be designed as a ball screw steering gear, although other types of gears are also conceivable.

[0064] The electro-hydraulic steering system 100 further includes a first line 104 through which the steering gear 102 can be supplied with hydraulic fluid and controlled.

[0065] Accordingly, the electro-hydraulic steering system 100 has a second line 106 through which the steering gear 102 can also be supplied with hydraulic fluid and controlled.

[0066] Furthermore, the steering system 100 has a valve device 108 for pressure reduction in the first line 104 and / or the second line 106, which is preferably designed as a low-pressure valve device, for example a low-pressure valve.

[0067] The valve assembly 108 can, for example, be a respective valve assembly 108 which is described in connection with Fig. 3 and 4 and / or Fig. 9.

[0068] It is understood that all structural and functional features relating to the valve assembly 108 according to Fig. 1 (and / or Fig. 2) may also be provided, alone or in combination, in the respective valve assembly 108 according to Figs. 3 and 4 and / or Fig. 9, and / or vice versa, and the associated advantages can be achieved accordingly.

[0069] The valve assembly 108 is connected on the input side to the first line 104 and also on the input side to the second line 106.

[0070] According to Fig. 1, the valve assembly 108 is also connected on the output side to a hydraulic tank 110 of the steering system 100 via a return line 112 of the steering system 100.

[0071] In other words, the steering system 100 comprises a hydraulic tank 110 and a return line 112, which is connected to the valve assembly 108 and the hydraulic tank 110. The valve assembly 108 can be actuated, preferably electromagnetically, by means of a control unit not shown in the figures, which is associated with or linked to the steering system 100. Alternatively or additionally, the valve assembly can be provided, at least partially, as a passively acting (low-pressure) valve assembly that is conditionally controllable by means of a pilot pressure (see Fig. 1, dashed lines).

[0072] In addition, the steering system 100 has a hydraulic pump 114 which is connected on the suction side to the hydraulic tank 110 via a suction line 116.

[0073] Furthermore, a leakage line 115 can be provided, which provides a connection between the hydraulic pump 114 and the hydraulic tank 110, preferably for draining a leakage of hydraulic fluid within the hydraulic pump, i.e., in particular, comparatively small amounts of hydraulic fluid.

[0074] On the other hand, the hydraulic pump 114 is connected to the first and second lines 104, 106.

[0075] The hydraulic pump 114 is designed as a double-acting hydraulic pump, so that depending on the direction of rotation either the first line 104 or the second line 106 can be printed.

[0076] Alternatively, it may also be conceivable that only a single-acting hydraulic pump is provided and is connected to the first and second lines 104, 106 via a corresponding switching valve (not shown in the figures), which connects the hydraulic pump to the first or the second line 104, 106 depending on the switching logic.

[0077] Alternatively, it is also conceivable that two hydraulic pumps could be provided, with one pump each assigned to or connected to the first and second lines 104, 106. The hydraulic pump 114 in Fig. 1 can be connected to the steering gear 102 via the first line 104 and, alternatively, via the second line 106, so that the actual connection depends on a direction control of the hydraulic pump 114.

[0078] Such control can be effected by a control unit that is assigned to or associated with the steering system 100 and is not shown in the figures.

[0079] As can be seen in Fig. 1, the hydraulic tank 110 is symbolically shown twice. This can be understood, for example, to mean that the hydraulic tank 110 may be formed from and / or have one or more tank sections and / or sub-tanks. In the present embodiment, it is preferably a (single) hydraulic tank 110.

[0080] It is also conceivable in this context that the hydraulic pump 114 is integrated into the tank.

[0081] Alternatively or additionally, it is also conceivable that hydraulic tank 110 and hydraulic pump 114 form separate units and are flanged together and connected via appropriate lines.

[0082] As can be seen in Fig. 1, the first line 104 and the second line 106 are connected to the intake line 116 and branch off from it accordingly.

[0083] In this case, a first check valve 118 is arranged in and / or on the first line 104.

[0084] Furthermore, a second check valve 120 is arranged in and / or on the second line 106.

[0085] As can also be seen in Fig. 1, the first and second check valves 118;

[0086] The two check valves can be arranged between the hydraulic pump 114 and the hydraulic tank 110. The two check valves can be arranged such that hydraulic fluid can be supplied from the hydraulic tank 110 to the hydraulic pump 114 along the first and second lines 104 and 106, respectively, while preventing backflow towards the hydraulic tank 110 through the first and second check valves 118 and 120, respectively.

[0087] The first check valve 118 and the second check valve 120 can serve and / or function as suction valves in this case.

[0088] Advantageously, a pressure build-up, in particular a pressure build-up controllable or controlled via a control unit assignable or associated to the steering system 100, for example the already named, can thus take place under the influence, preferably support, of the suction valves.

[0089] In other words, the suction valves, i.e. the first and second check valves 118, 120, can assist the hydraulic pump 114 in building up pressure, especially along the first and second lines up to the steering gear 102.

[0090] It is conceivable that the hydraulic pump 114, the first check valve 118, and the second check valve 120 can be designed as a single, preferably structurally integrated, module 126, as schematically indicated by the dashed rectangle in Fig. 1. This module 126 can preferably be fluidically connected to, or be connected to, the first line 104, the second line 106, and the hydraulic tank 110, or provide a fluid connection, at least temporarily.

[0091] As can be seen in Fig. 1, the steering system 100 also has a temperature sensor 122 and a pressure sensor 124, which are installed in and / or on the intake line 116.

[0092] The temperature sensor 122 and the pressure sensor 124 can be used between the

[0093] hydraulic tank 110 and the point or area of ​​the suction line 116 where the first line 104 and the second line 106 branch off from the suction line 116.

[0094] It is understood that the temperature sensor 122 and the pressure sensor 124 can be connected or are connected to a control unit that can be assigned to or associated with the steering system 100, for example the one already named, for controlling an operation and / or partial operation of the steering system 100 via signal technology.

[0095] Furthermore, it is understood that, in the case of the described module 126, the temperature sensor 122 and the pressure sensor 124 can be in operative communication with the module 126 and / or can be at least partially provided in it and / or connected to it.

[0096] The function of the steering system 100 according to the embodiment shown in Fig. 1 can now be described as follows:

[0097] As soon as the hydraulic pump 114 is driven by the motor M, which can be an electric motor (e.g. counterclockwise), it can pressurize the section of the first line 104, which extends to the steering gear 102 and to a first connection 128 of the valve assembly 108, with hydraulic fluid pressure.

[0098] During pressure build-up, the hydraulic pump 114 can be supported by the second check valve 120, which acts as a suction valve, especially when the hydraulic pump 114 generates a sufficient vacuum along the second line 106, which leads to the opening of the second check valve 120.

[0099] Consequently, the hydraulic pump 114 and the steering gear 102 are connected to each other via the first line 104 and the connection of the steering gear 102 connected to the first line 104 is printed.

[0100] As a result, the pressure in the associated first pressure chamber of the steering gear 102 increases, and the piston is forced into a displacement movement because the pressure in the opposite, second pressure chamber is lower, thus achieving steering assistance. In this sense, the second pressure chamber can be understood as a low-pressure chamber.

[0101] The pressure in the opposite second pressure chamber is therefore lower because the connection of the steering gear 102 is connected to the return line 112 via the section of the second line 106 and via the valve assembly 108.

[0102] In this case, the hydraulic fluid is displaced from the opposite, second pressure chamber and via the valve assembly 108 into the return line 112 and then fed back to the hydraulic tank 110 via the return line 112.

[0103] A rapid return of the hydraulic fluid can be initiated, for example, if the operating pressure in the first line 104 is higher compared to the operating pressure in the second line 106 and the second line 106 is connected to the return line 112 by means of the at least partially controllable valve device 108.

[0104] The second line 106 can thus be connected to the return line 112 depending on the pressure difference between the first line 104 and the second line 106 and the actuable valve device 108, preferably by means of the electromagnetically actuated valve device 108.

[0105] This enables a rapid pressure relief phase in the pressure chamber of the steering gear 102 connected to the second line 106, and thus the response of the steering system 100 can be improved, preferably enabling a faster system response and a better steering feel.

[0106] It should be understood that the hydraulic pump 114 can preferably only be driven in one direction of rotation, and therefore only the first or the second line 104, 106 can be printed at any given time.

[0107] In the case described above, the first line 104 is therefore printed by the hydraulic pump 114, whereas the second line 106 is not printed, at least in the section between hydraulic pump 114 and steering gear 102 and / or valve assembly 108.

[0108] If the direction of rotation of the hydraulic pump 114 is reversed, the previously described relationship or case occurs in exactly the opposite way, as described below:

[0109] As soon as the hydraulic pump 114 is driven by the motor M (now clockwise) it pressurizes the section of the second line 106, which extends to the steering gear 102 and to a second port 130 of the valve assembly 108.

[0110] During pressure build-up, the hydraulic pump 114 is supported by the first check valve 118, which acts as a suction valve.

[0111] Consequently, the hydraulic pump 114 and the steering gear 102 are now connected to each other via the second line 106 and the connection of the steering gear 102 connected to the second line 106 is printed.

[0112] As a result, the pressure in the associated second pressure chamber of the steering gear 102 increases, and the piston is forced into a displacement movement because the pressure in the opposite first pressure chamber is now lower, thus achieving steering assistance. In this case, the first pressure chamber of the steering gear 102 can be considered a low-pressure chamber.

[0113] The pressure in the opposite first pressure chamber is therefore lower because the connection of the steering gear 102 is connected to the return line 112 via the section of the first line and via the valve assembly 108.

[0114] In this case, the hydraulic fluid is displaced from the opposite, first pressure chamber and directed via the valve assembly 108 into the return line 112, and then further via the return line 112 back to the hydraulic tank 110. Rapid return of the hydraulic fluid can be initiated if the operating pressure in the second line 106 is higher than the operating pressure in the first line 104 and the first line 104 is connected to the return line 112 by means of the at least partially controllable valve assembly 108.

[0115] Thus, the first line 104 can be connected to the return line 112 depending on the pressure difference between the first line 104 and the second line 106 by means of the actuable valve device 108, preferably by means of the at least partially actively controllable valve device 108.

[0116] This enables a rapid pressure relief phase in the pressure chamber of the steering gear 102 connected to the first line 104, and thus the response of the steering system 100 can be improved, preferably enabling a faster system response and a better steering feel.

[0117] It should be understood that the hydraulic pump 114 is preferably always driven in only one direction of rotation and therefore only the first or the second line 104, 106 can be printed at any given time.

[0118] In the second case described above, the second line 106 is therefore printed by the hydraulic pump 114, whereas the first line 104 is not printed, at least in the section between hydraulic pump 114 and steering gear 102 and / or valve assembly 108.

[0119] According to the present invention, the pressure in the first or second line 104, 106 can be used, at least partially, as a control pressure for the valve assembly 108 to enable a pressure reduction or pressure release in the respective other line 106, 104 and the corresponding pressure chamber. This advantageously allows for a rapid pressure relief phase in the pressure chamber and consequently accelerates the response of the entire steering system. This operational behavior can also be further enhanced and accelerated by at least partially targeted actuation of the valve assembly 108, thus further improving the system dynamics and response accuracy of the valve assembly 108 and ultimately of the steering system 100.

[0120] In summary, it should also be noted that, depending on the direction of rotation of the pump, either the first or the second line 104, 106 is printed, so that the steering gear 102 is preferably always printed by only one of the lines 104, 106 and thus the other line 104, 106 (which is not printed) can be connected or is connected to the return line 112 via the valve device 108.

[0121] Since the piston displacement direction of the piston in the steering gear 102 also changes depending on the steering direction, the control / pressure of the steering gear 102 via the first line 104 or the second line 106 also changes accordingly. By enabling a rapid pressure reduction by means of the valve assembly 108, the piston displacement direction can also be carried out quickly and a fast and dynamic change of steering direction can be achieved.

[0122] Fig. 2 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 200.

[0123] The further embodiment of the steering system 200 shown in Fig. 2 has essentially the same structural and functional features as the embodiment of the steering system 100 shown in Fig. 1, so that the differences between the embodiments will be described primarily below.

[0124] As can be seen in Fig. 2, the steering system 200 has a further check valve 202.

[0125] The additional check valve 202 is arranged in and / or on the return line 112. In a sense, this is a return line check valve 202.

[0126] The check valve 202 is arranged according to Fig. 2 such that backflow from the hydraulic tank 110 to the valve assembly 108 can be prevented. The additional check valve 202 advantageously minimizes leakage losses, particularly with respect to the valve assembly 108, which can lead to reduced maintenance requirements for the steering system 200.

[0127] It is understood that the function of the steering system 200 of Fig. 2 corresponds essentially to the function of the steering system 100 of Fig. 1.

[0128] In the operation of the steering system 200 according to Fig. 2, the hydraulic fluid must, starting from the valve assembly 108, flow downstream in the direction of the hydraulic tank 110, additionally pass through the further check valve 202.

[0129] Referring to Figs. 3 and 4, an embodiment of the valve assembly 108 will be described below, which can be the valve assembly 108 of the steering system 100 of Fig. 1 and / or of the steering system 200 of Fig. 2 and / or of a respective steering system 400, 500, 600, 700, 800, 1100, 1200 of Figs. 5 to 8 and Figs. 10 to 12.

[0130] Figures 3 and 4 show a schematic sectional view of an embodiment of a valve assembly 108 of a steering system 100, 200.

[0131] The valve assembly 108 has a housing body 300, which can be designed, for example, as a single piece or in multiple parts.

[0132] A main chamber 302 is formed in the housing body 300.

[0133] In this case, the first connection 128 leads into the main chamber 302 and the second connection 130 also leads into the main chamber 302.

[0134] The first connection 128 and the second connection 130 are arranged next to each other with respect to the main chamber 302.

[0135] Furthermore, the valve assembly 108 has a third port 310 to which the return line 112 can be connected or is connected. The first port 128, the third port 310, and the second port 130 are arranged side by side on the housing body 300. In particular, the third port 310 is located between the first port 128 and the second port 130.

[0136] The valve assembly 108 further comprises a spring element 304, a second electromagnet 306 and a switching element 308.

[0137] The spring element 304 and the switching element 308 are arranged in the main chamber 302.

[0138] The switching element 308 is preferably designed as, for example, a block-like sliding element 312.

[0139] The switching element 308 is arranged between the spring element 304 and the electromagnet 306.

[0140] The spring element 304 is arranged with one end on the inside of the housing body 300 and with the opposite end on the inside of the switching element 308.

[0141] The electromagnet 306 is arranged on the outside of the housing body 302 and projects into the main chamber 302 with an actuating rod 314.

[0142] The end of the actuating rod 314 which protrudes into the main chamber 302 rests against the switching element 308, opposite the spring element 304, and / or engages with the switching element 308 there.

[0143] A stop element 316 can also be formed on the actuating rod 314, which can be brought into contact and / or engagement with a first stop 318 and a second stop 320 of the valve assembly 108 depending on the actuation of the electromagnet 306. It can be provided that the first and / or the second stop 318, 320 can be provided and / or formed on the housing body 302 and / or on a further body that can be arranged on or is arranged on the housing body 302 and / or on a main body of the electromagnet 306. It is conceivable that the further body is arranged between the housing body and the main body.

[0144] The first stop 318 corresponds to a first switching position of the switching element 308, in which the first line 104 can be connected to or is connected to the return line 112 (see Fig. 4).

[0145] The second stop 320 corresponds to a second switching position of the switching element 308, in which the second line 106 can be connected to or is connected to the return line 112 (see Fig. 3).

[0146] As can be seen in Figs. 3 and 4, the switching element 308 has a recess 322 on the outer surface, for example in the form of a groove.

[0147] The recess 322 is always aligned with the third terminal 310 and, depending on the switching state of the switching element 308, can be aligned with either the first or the second terminal 128, 130.

[0148] This can be understood to mean that, depending on the position of the switching element 308 in the main chamber 302, the first connection 128 can be fluidically connected to the third connection 310 via the recess 322, or correspondingly the second connection 130 can be connected to the third connection 310.

[0149] As can be seen in Fig. 3, the second terminal 130 can be connected to the third terminal 310, i.e., the second line 106 to the return line 112, via the recess 322, or is connected when the stop element 316 rests against the second stop 320. Furthermore, the spring element 304, according to Figs. 3 and 4, can tension or pre-tension the switching element 308 in the switching position according to Fig. 3.

[0150] As can be seen in Fig. 4, the first connection 128 can be connected to the third connection 310, i.e. the first line 104 to the return line 112, via the recess 322, when the stop element 316 rests against the first stop 318.

[0151] Preferably, the switching element 308 can be moved into this position by actuating the electromagnet 306 and / or the pressure of the second line 106. The spring force of the spring element 304 can be overcome, in particular, by actuating the electromagnet 306. The spring element 304 is compressed in this switching position.

[0152] When printing occurs (according to Figs. 3 and 4: print P1) via the first terminal 128 and / or corresponding control of the electromagnet 306, the switching element 308 is caused to move towards the second terminal 130 by means of a pressure force exerted or exerted by the spring element 304 (until the stop element 316 abuts the second stop 320). This state is shown by way of example in Fig. 3.

[0153] The recess 322 shifts towards the second port 130 and is preferably brought into alignment with it, in addition to the third port 310, so that a fluid connection between the third port 310 and the second port 130 is enabled or facilitated via the aforementioned recess 322 (see arrow in Fig. 3). The second port 130 can be connected to the third port 310 via the recess 322.

[0154] This can be understood in particular to mean that if the pressure (according to Figs. 3 and 4: pressure P1) applied via the first connection 128 is higher than the pressure (according to Figs. 3 and 4: pressure P2) applied to the second connection 130, and / or if the electromagnet 306 is controlled accordingly, the switching element 308 is moved in such a way that the second connection 130 is or can be fluidically connected to the third connection 310 (see Fig. 3).

[0155] It is understood that the operation described above also functions in reverse. This can be understood in particular to mean that if the pressure applied via the second port 130 is higher than the pressure applied to the first port 128, and / or if the electromagnet 306 is appropriately controlled, the switching element 308 is moved such that the first port 128 is fluidically connected to the third port 310 (via the recess 322). This condition is shown, for example, in Fig. 4.

[0156] In a sense, by making the first terminal 128 connectable or connected to the first line 104, the second terminal 130 to the second line 106 and the third terminal 310 to the return line 112, the first line 104 and / or the second line 106 can be connected to the return line 112 by means of the switching element 308 (via the recess 322) or can be blocked with respect to the return line 112.

[0157] In other words, the first line 104 and / or the second line 106 can be connected to or blocked from the return line 112, depending on a pressure difference between the first line 104 and / or the second line 106 and / or by appropriate control of the electromagnet 306, by means of the valve device 108, and in particular the switching element 308.

[0158] Fig. 5 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 400.

[0159] The further embodiment of the steering system 400 shown in Fig. 5 has essentially the same structural and functional features as the embodiment of the steering system 100 shown in Fig. 1, so that the differences between the embodiments will be described primarily below.

[0160] As can be seen in Fig. 5, the steering system 400 includes a separately designed backup device, in this case designed as a backup valve device, in particular here as a backup valve 402. It is understood that the representation shown in Fig. 5 is purely exemplary and that a functionally equivalent unit to the backup valve 402 could also be provided.

[0161] According to the present invention, all embodiments of a steering system 100, 200, 400, 500, 600, 700, 800, 1100, 1200 can each be provided with a backup valve 402, either individually or externally, as shown in Figures 5, 6, 8, 10, 11, and 12, or the backup valve 402 can be integrated, in particular integrated into the valve assembly 108, as shown in Figures 1, 2, and 7. Therefore, the individual embodiments of the steering system 100, 200, 400, 500, 600, 700, 800, 1100, 1200 can be configured with a backup valve 402, either individually or integrally.

[0162] Alternatively, it may also be provided that the individual embodiments of the steering system 100, 200, 400, 500, 600, 700, 800, 1100, 1200 can be provided or used entirely without an external or integrally provided backup valve 402.

[0163] As shown in Fig. 5, the backup valve 402 can be connected, at least indirectly, to the first line 104 via the pressure chamber of the steering gear 102 assigned to the first line 104.

[0164] On the other hand, the backup valve 402 can be indirectly connected to the second line 106 via the respective pressure chamber of the steering gear 102 assigned to the second line 106.

[0165] The respective pressure chambers of the steering gear 102 can be connected and preferably short-circuited by means of the backup valve 402, especially in an emergency situation or in the event of a fault.

[0166] This allows the safety and / or reliability of the steering system 400 to be further improved, as the pressure chambers of the steering gear 102 can be connected in an emergency situation, thereby ensuring a corresponding pressure reduction or pressure equalization and thus a steering function in terms of the mobility of the (hydraulic) piston in the steering gear at all times.

[0167] In a sense, the backup valve 402 can thus form and / or enable a fault case circuit not specifically indicated in the figures and / or function as such.

[0168] It is understood that the function of the steering system 400 of Fig. 5 corresponds essentially to the function of the steering system 100 of Fig. 1.

[0169] In an emergency, however, a short circuit of the pressure chambers of the steering gear 102 can be caused or initiated by the backup valve 402, so that a corresponding pressure reduction or pressure equalization and consequently steerability or a steering function can always be guaranteed even in such a fault case.

[0170] In other words, in an emergency, the backup valve 402 can switch from its closed position to a flow position in order to provide a fluid short circuit between the two pressure chambers of the steering gear 102.

[0171] It is understood that the backup device or the backup valve device, in particular the backup valve 402, can be controlled or operated via a control unit that can be assigned to or associated with the steering system 400.

[0172] Fig. 6 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 500.

[0173] The further embodiment of the steering system 500 shown in Fig. 6 has essentially the same structural and functional features as the embodiments of the steering system 200, 400 shown in Figs. 2 and 5.

[0174] In a sense, the embodiment of the steering system 500 shown in Fig. 6 is a combination of the embodiments of the steering systems 200 and 400 shown in Figs. 2 and 5. Therefore, the following discussion will focus primarily on the special features and differences of the embodiment shown in Fig. 6.

[0175] In other words, the steering system 500 of Fig. 6 includes both the backup valve 402 described above and the return line check valve 202 described above.

[0176] It is understood that the function of the steering system 500 of Fig. 6 essentially corresponds to the function of the steering system 200 of Fig. 2 and the function of the steering system of Fig. 5, or can combine their functionalities within itself.

[0177] Fig. 7 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 600.

[0178] The further embodiment of the steering system 600 shown in Fig. 7 has essentially the same structural and functional features as the embodiment of the steering system 400 shown in Fig. 5, so that the differences between the embodiments will be described primarily below.

[0179] As can be seen in Fig. 7, the steering system 600 is free of check valves.

[0180] In other words, the steering system 600 does not have either the first or the second check valve 118, 120.

[0181] The first and second lines 104, 106 are connected to the hydraulic pump 114, which in turn is connected to the hydraulic tank 110 via the suction line 116.

[0182] Optionally, the temperature sensor 122 and / or the pressure sensor 124 can also be provided on and / or in the intake line 116. The steering system 600 of Fig. 7 also has a backup valve 402, which is integrated into the valve assembly 108 and has the functionality described above.

[0183] Such a backup valve 402 integrated in the valve assembly 108 is shown, for example, in the embodiment of a valve assembly 108 in Fig. 9, whereby it is understood that the embodiment shown in Fig. 9 is only one possible exemplary embodiment.

[0184] It is understood that the function of the steering system 600 of Fig. 7 corresponds essentially to the function of the steering system 400 of Fig. 5, except that in this case the support of the hydraulic pump 114 by the check valves 118, 120 which function as suction valves is omitted.

[0185] It should also be understood that the steering system 600 of Fig. 7 can also be designed without a backup valve. In a sense, the steering system 600 of Fig. 7 can be designed without a backup valve and / or without a check valve. Thus, the steering system 600 according to Fig. 7 can, for example, be designed like the steering system 100 according to Fig. 1, without the two check valves 118, 120 and the associated functional support of the hydraulic pump 114 in the form of suction valves.

[0186] Fig. 8 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 700.

[0187] The further embodiment of the steering system 700 shown in Fig. 8 has essentially the same structural and functional features as the embodiment of the steering system 600 shown in Fig. 7, so that the differences between the embodiments will be described primarily below.

[0188] As can be seen in Fig. 8, the steering system 700 is also free of a check valve. The steering system 700 shown in Fig. 8 also has a backup valve 402.

[0189] In the present embodiment, however, the backup valve 402 is designed as a separate unit (and is not integrated into the valve assembly 108), as already described in connection with Figs. 5 and 6.

[0190] It is understood that the function of the steering system 700 of Fig. 8 ultimately corresponds essentially to the function of the steering system 600 of Fig. 7.

[0191] Fig. 9 shows a schematic sectional view of a further embodiment of a valve device 108 for a steering system, in particular a steering system 100, 200, 600 according to Figs. 1, 2 and 7.

[0192] The valve assembly 108 shown in Fig. 9 is in particular the valve assembly 108 with integrated backup valve 402 already described in general terms. It is therefore understood that the valve assembly 108 shown in Fig. 9 can in particular be the valve assembly 108 shown in Fig. 7.

[0193] Likewise, a backup valve 402 shown, for example, in Fig. 6 can be implemented in the same way as an integrated backup valve in the valve assembly 108 according to Fig. 9.

[0194] The further embodiment of the valve device 108 shown in Fig. 9 has essentially the same structural and functional features as the embodiment of the valve device 108 shown in Figs. 3 and 4, so that the differences between the embodiments will be described primarily below.

[0195] As can be seen in Fig. 9, the backup valve 402 can be integrated into the housing body 300. The backup valve 402 has a slide 326, a preload element 328, an electromagnet 330 and a chamber 332.

[0196] The slide 326 is located in chamber 332.

[0197] Chamber 332 is connected to main chamber 302 via at least two fluid passages.

[0198] A fluid passage is arranged in the housing body 300 on one side of the switching element 308, so that this fluid passage connects or can connect the part of the main chamber 302 attributable to the first terminal 128 with the chamber 332.

[0199] The other fluid passage is arranged in the housing body 300 on the opposite side of the switching element 308, so that this fluid passage connects or can connect the part of the main chamber 302 attributable to the second connection 130 with the chamber 332.

[0200] The slide 326 is connected to the electromagnet 330, in particular operatively connected.

[0201] By means of the electromagnet 330, the slide 326 can be moved across a respective fluid passage by means of a control unit that can be assigned to or associated with the steering system, thereby making it optionally lockable and / or openable.

[0202] The preload element 328 provided in the backup valve 402 tensions the slide 326 in the fluid passage that corresponds to the second port 130. In Fig. 9, the preload element 328, which can be a spring element, is compressed. In other words, the electromagnet 330 can be controlled or actuated such that the other fluid passage through the slide 326 is closed. As can be seen in Fig. 9, the slide 326 also has at least one connecting channel 334, which extends through the slide 326 along a longitudinal axis.

[0203] This can be understood in particular to mean that if the slide 326 does not cover any of the said fluid passages in the direction of the first or second connection 128, 130 or the main chamber 302, in other words, is arranged between the fluid passages, the said fluid passages are fluidically connected to each other.

[0204] In this case, the first connection 128 and the second connection 130 are also fluidically connected to each other via the fluid passages, the chamber 332 and the connecting channel 334.

[0205] Thus, the first and second lines 104, 106 can be connected to each other in this way and, in particular, short-circuited.

[0206] The backup valve 402 is thus indirectly connected or connectable to the pressure chamber of the steering gear 102 assigned to the first line 104.

[0207] On the other hand, the backup valve 402 is indirectly connected or connectable to the pressure chamber of the steering gear 102 assigned to the second line 106.

[0208] By means of the backup valve 402, the first and second lines 104, 106 and in particular the respective pressure chambers of the steering gear 102 can be connected and preferably short-circuited.

[0209] This further improves the safety and / or reliability of the steering system by allowing the two lines 104 and 106, and thus the pressure chambers of the steering gear 102, to be connected in an emergency. In particular, appropriate pressure relief and therefore steering capability can always be guaranteed. In an emergency, a short circuit of the pressure chambers of the steering gear 102 can be initiated by the backup valve 402 (by opening both of the described fluid passages via the slide valve 326), so that appropriate pressure relief and consequently steering capability can always be guaranteed even in such a case.

[0210] In other words, in an emergency, the backup valve 402 can switch from a closed position (see Fig. 9) to a flow position (arrangement of the slide 326 between the fluid passages) to enable the aforementioned short circuit.

[0211] The valve assembly 108 described in connection with Figs. 3 and 4 can be provided with such an integrated backup valve 402 as described in connection with Fig. 9.

[0212] Fig. 10 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 800.

[0213] The further embodiment of the steering system 800 shown in Fig. 10 has essentially the same structural and functional features as the embodiment of the steering system 500 shown in Fig. 6, so that the differences between the embodiments will be described primarily below.

[0214] As can be seen in Fig. 10, the steering system 800 has a filter device 802.

[0215] The filter device 802 is arranged in the return line 112.

[0216] In particular, the filter device 802 is arranged between the return line check valve 202 and the hydraulic tank 110.

[0217] In particular, the return line check valve 202 can be arranged along the return line 112 such that an oil flow or oil leakage from the valve assembly 108 via the filter assembly 802 is provided or enabled, and a reverse backflow, i.e., via the filter assembly 802 to the valve assembly 108, can be prevented. This arrangement has the advantage that the filter or filter assembly 802 does not have to be located on the high-pressure side, but rather on the low-pressure side in the return line 112 to the hydraulic tank 110.

[0218] Consequently, the filter or filter assembly 802 can be designed to be mechanically less robust and structurally simpler, since it is not subjected to such high pressures.

[0219] In accordance with Fig. 10, an additional or supplementary hydraulic tank 110 can be provided, in addition to and preferably in connection with the hydraulic tank 110 outside the construction module 126, within the construction module 126.

[0220] Consequently, cost advantages can also be realized through such a design of the filter or filter device 802.

[0221] Fig. 11 shows a schematic representation of a (circuit) arrangement of a further embodiment of a steering system 1100.

[0222] Compared to the embodiment in Fig. 10, the steering system 1100 according to Fig. 11 differs particularly in the arrangement of additional check valves 204 and 206 in the first line 104 and the second line 106 between the valve assembly 108 and the hydraulic pump 114. Furthermore, according to Fig. 11, and in contrast to Fig. 10, it may be provided that no check valve 202 (cf. Fig. 10) is present in the return line 112. Therefore, the following discussion will focus primarily on the aforementioned differences according to Fig. 11.

[0223] According to Fig. 11, the filter device 802 is provided in the return line 112, between the hydraulic tank 110 and the valve device 108, without an additional check valve 202.

[0224] A third check valve 204 can be arranged in the first line 104 and a fourth check valve 206 in the second line 106, in particular between the valve assembly 108 or the steering gear 102 and the hydraulic pump 114, so that backflow to the hydraulic pump 114 or the suction of hydraulic fluid by the hydraulic pump 114 can be prevented.

[0225] In the first and second lines 104; 106, two check valves 118; 120; 204; 206 can each be arranged, so that, depending on a direction of rotation or delivery of the hydraulic pump 114, a targeted suction of hydraulic fluid from the hydraulic tank 110 is made possible.

[0226] The check valves 118; 120; 204; 206 prevent or stop the intake of hydraulic fluid from the steering gear 102 or the valve device 108 along the first or second line 104; 106 by the hydraulic pump 114.

[0227] Figure 12 shows a schematic representation of a (circuit) arrangement of another embodiment of a steering system 1200. The following discussion focuses primarily on the difference between the embodiment according to Figure 12 and the embodiment according to Figure 11.

[0228] In particular, as shown in Fig. 12, the check valve 202 is provided in the return line 112, especially in addition to the check valves 118; 120; 204; 206 along the first and second lines 104; 106.

[0229] Preferably, the check valve 112 according to Fig. 12 is provided between the filter unit 802 and the valve assembly 108.

[0230] In particular, the return line check valve 202 according to Fig. 12 can be arranged along the return line 112 such that an oil flow or oil leakage from the valve assembly 108 via the filter assembly 802 into the hydraulic tank 110 is provided or enabled, and a reverse backflow, i.e., from the hydraulic tank 110 via the filter assembly 802 to the valve assembly 108, can be prevented (see also Figs. 2, 6 and 10). In summary, the present invention advantageously provides an electro-hydraulic steering system which, by means of an at least partially actively controllable valve assembly, in particular as a low-pressure valve assembly, allows a rapid and reliable pressure reduction in a (low-pressure chamber of the steering gear) and thus reliably increases or accelerates the system dynamics or system response of the steering system during operation, especially during rapid steering maneuvers.

[0231] This ensures both optimized hydraulic power steering and improved steering feel for the driver of a vehicle.

[0232] In particular, an actively, preferably electromagnetically, controllable design of the valve unit can ensure a cost-effective, low-maintenance and simple implementation for reliable and rapid pressure reduction in a (low-pressure chamber of the steering gear).

[0233] Furthermore, the preferred embodiment with a valve unit that is particularly electromagnetically controllable and / or adjustable allows for an advantageous design with regard to the installation space, the cost and the weight of a steering system in accordance with the present invention.

[0234] Furthermore, by incorporating a backup valve, either as an additional component of the steering system or as a variant integrated into the valve unit, safe operation of the steering system can be ensured even in emergencies or in the event of a fault.

[0235] REFERENCE MARK LIST

[0236] 100 steering system

[0237] 102 Steering gear

[0238] 104 first line

[0239] 106 second line

[0240] 108 Valve assembly

[0241] 110 hydraulic tank

[0242] 112 Return line

[0243] 114 Hydraulic pump

[0244] 115 Leakage line

[0245] 116 Intake manifold

[0246] 118 first check valve

[0247] 120 second check valve

[0248] 122 Temperature sensor

[0249] 124 Pressure sensor

[0250] 126 Building module

[0251] 128 first connection

[0252] 130 second connection

[0253] 200 steering system

[0254] 202 Return line check valve

[0255] 204 third check valve

[0256] 206 fourth check valve

[0257] 300 housing bodies

[0258] 302 Main Chamber

[0259] 304 Spring element

[0260] 306 Electromagnet

[0261] 308 Switching element

[0262] 310 third connection

[0263] 312 Sliding element

[0264] 314 Actuating rod

[0265] 316 Stop element

[0266] 318 first stop 320 second stop

[0267] 322 Exclusion

[0268] 324 second spring element

[0269] 326 Slide 328 Preloading element

[0270] 330 Electromagnet

[0271] 332nd Chamber

[0272] 334 Connection channel

[0273] 400 Steering system 402 Backup valve

[0274] 500 steering system

[0275] 600 steering system

[0276] 700 steering system

[0277] 800 Steering system 802 Filter system

[0278] 1100 steering system

[0279] 1200 steering system

Claims

PATENT CLAIMS 1. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) for a vehicle, in particular a commercial vehicle, comprising: - at least one steering gear (102), in particular a screw steering gear; - at least one first line (104) through which the steering gear (102) can be supplied with hydraulic fluid and / or controlled; - at least one second line (106) through which the steering gear (102) can be supplied with hydraulic fluid and / or controlled; and - at least one valve device (108) connected or connectable to the first line (104) and / or the second line (106), in particular a low-pressure valve device, for pressure reduction in the first line (104) and / or the second line (106), wherein the valve device (108) is actuated as required, in particular electromagnetically actuated.

2. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to claim 1 , characterized in that the steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) has at least one hydraulic tank (110) and at least one return line (112) which is connected or connectable to the valve assembly (108) and the hydraulic tank (110).

3. Electro-hydraulic steering system (200; 500; 800; 1200) according to claim 2, characterized in that the steering system (200; 500; 800) has at least one check valve (202) which is arranged in and / or on the return line (112).

4. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to one of the preceding claims, characterized in that the first line (104) and / or the second line (106) is controlled depending on a pressure difference between the first line (104) and / or the second line. (106) can be connected to the return line (112) by means of the valve assembly (108).

5. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to one of the preceding claims, characterized in that the first line (104) can be connected to or is connected to the return line (112) by means of the valve device (108) when a pressure in the second line (106) is higher than a pressure in the first line (104), and / or the second line (106) can be connected to or is connected to the return line (112) by means of the valve device (108) when a pressure in the first line (104) is higher than a pressure in the second line (106).

6. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to one of the preceding claims, characterized in that the valve assembly (108) has at least one electromagnet (306) and a switching between the first line (104) and the second line (106) for pressure reduction in one of the lines (104, 106) is electromagnetically controlled or controllable.

7. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to claim 6, characterized in that the valve assembly (108) has at least one spring element (304) and at least one switching element (308) which is arranged, in particular between the spring element (304) and the electromagnet (306), such that a magnetic force of the at least one electromagnet (306) for adjusting the at least one switching element (308) opposes the at least one spring element (304).

8. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to claim 7, characterized in that the first line (104) and / or the second line (106) can be connected to the return line (112) by means of the switching element (308).

9. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to claim 7 or 8, characterized in that the switching element (308) can be moved by means of the spring element (304) into a first switching position in which the first line (104) or the second line (106) is connected to the return line (112), and / or the switching element (308) can be moved by means of the electromagnet (306), in particular against a spring force of the spring element (304), into a second switching position in which the second line (106) or the first line (104) is connected to the return line (112).

10. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to claim 9, characterized in that the first switching position and the second switching position of the switching element (308) corresponds to and / or is predetermined by a respective stop (318, 320) provided in the valve assembly (108).

11. Electro-hydraulic steering system (400; 500; 600; 700; 800; 1100; 1200) according to one of the preceding claims, characterized in that the steering system (400; 500; 600; 700; 800) has a backup device (402), in particular a backup valve device, by means of which the first and the second line (104, 106) can be connected directly or indirectly, in particular short-circuited, wherein preferably the backup device (402) is designed as a separate device or is integrated in the valve device (108).

12. Electro-hydraulic steering system (100; 200; 400; 500; 800; 1100; 1200) according to one of the preceding claims, characterized in that at least one first check valve (118; 204) is arranged in the first line (104) and / or at least one second check valve (120; 206) is arranged in the second line (106).

13. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800) according to one of the preceding claims, characterized in that the steering system (100; 200; 400; 500; 600; 700; 800) has at least one hydraulic pump (114) which can be connected to or is connected to the first line (104) and the second line (106) and which can be connected to or is connected on the suction side via a suction line (116) to at least one hydraulic tank (110).

14. Electro-hydraulic steering system (100; 200; 400; 500; 800; 1100; 1200) according to claims 12 and 13, characterized in that the first check valve (118) is arranged in the first line (104) and / or the second check valve (120) is arranged in the second line (106) between the hydraulic pump (114) and the at least one hydraulic tank (110).

15. Vehicle, in particular commercial vehicle, with an electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 1100; 1200) according to one of the preceding claims.

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