Electrohydraulic steering system

Abstract

The invention relates to an electrohydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) 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). 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; 900; 1000).

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. Furthermore, it is an object of the invention to provide a vehicle with such an electro-hydraulic steering system.

[0008] This problem is solved 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. In particular, it can be provided that an electro-hydraulic steering system for a vehicle, in particular 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.

[0009] The invention is based in particular on the fundamental idea 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 use a pressure or system pressure of the steering system to enable a pressure reduction or pressure decrease in a relevant (low-)pressure chamber of the steering gear via the first and / or the second line and the (actively controllable and / or passively acting) valve assembly, thereby enabling a rapid pressure relief phase in said (low-)pressure chamber and consequently accelerating the response of the entire steering system.

[0010] For example, a relevant pressure chamber of the steering gear can be connected to a hydraulic reservoir of the steering system via the first and / or second line and the aforementioned valve assembly to enable the aforementioned pressure relief phase and consequently the aforementioned response. This can further result in improved steering behavior, and the driver can receive the necessary steering assistance from the system in a timely manner, depending on the situation.

[0011] In other words, reducing or decreasing the pressure can improve steering feel for the driver, and system dynamics or response can be accelerated or accelerated. The steering system may be designed to include at least one hydraulic reservoir and at least one return line connected or connectable to the valve assembly and the hydraulic reservoir.

[0012] This provides a simple structure for hydraulic fluid handling and, in particular, hydraulic fluid return, starting from the valve assembly. 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 along the return line to the hydraulic tank. Thus, 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 reduction in the relevant (low-)pressure chamber.

[0013] 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.

[0014] 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.

[0015] 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 device, depending on a pressure difference between the first line and / or the second line.

[0016] 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, this also allows pressure to be quickly built up again in the other pressure chamber, thus advantageously ensuring a high steering speed and / or steering change speed for the driver.

[0017] 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.

[0018] In a sense, the 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 used as control pressure for the valve assembly. In other words, since the piston displacement direction also changes depending on the steering direction, the control / pressure of the steering gear can accordingly change, sometimes via the first line and sometimes via the second. As soon as the first or second line is pressurized, this pressure can be tapped 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. Since a separate control of the valve assembly is not strictly necessary, the steering system can thus achieve a higher functional density with a simpler design.

[0019] Furthermore, it may be provided that the first line and / or the second line can be blocked by means of the valve device with respect to the return line, depending on an equal pressure in the first line and / or the second line.

[0020] This allows the pressures prevailing in the respective lines and / or pressure chamber to be kept in balance and / or an unwanted pressure drop or pressure reduction can be reliably avoided, which, for example, can prevent unwanted steering assistance and preferably reliably ensure straight-line driving of a vehicle in which the steering system can be installed or is installed.

[0021] It may be provided that the valve assembly has at least one first and one second spring element and at least one switching element arranged between the first and the second spring element.

[0022] For example, the spring elements may be designed to be passive. The valve assembly can be simple and robust, requiring minimal installation space. This can, for instance, facilitate simple, cost-effective, and efficient manufacturing, assembly, and / or maintenance of the valve assembly.

[0023] It goes without saying, however, that the valve device can alternatively be designed as an actively controllable valve device, for example as a solenoid valve device.

[0024] 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 or can be blocked with respect to the return line.

[0025] This design offers the advantage that both the connecting and locking functions are performed by the switching element, thus reducing the failure probability typically associated with a multitude of different components and increasing the reliability of the steering system. Furthermore, this design allows for enhanced functionality of the steering system with a simple structure. In other words, a structurally very simple and cost-effective design is provided for the functionality of switching between the lines for pressure relief.

[0026] It may be designed so that the switching element can be tensioned into a starting position by means of the first and second spring elements, in which the first and second lines are blocked with respect to the return line. For example, the spring elements may be in equilibrium in this position. This can enable a protective or safety function to prevent, for example, unintended power steering and / or unintentional pressure release.

[0027] 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.

[0028] For example, the switching element may be designed as a piston element and / or incorporate one. This design can advantageously be cost-effective and simple in maintenance and manufacturing.

[0029] The steering system may be provided with 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, in particular short-circuited.

[0030] 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.

[0031] 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 advantageously be 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. Preferably, the backup device can be designed as a separate or independent unit or integrated into the valve assembly. This, in particular, facilitates the maintenance of the backup device and / or saves installation space.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 as priming valves. Advantageously, pressure build-up, especially pressure build-up controllable or controlled via a control unit associated with 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 assist the hydraulic pump in building up pressure, in particular by providing (as needed) a supply of hydraulic fluid from the hydraulic tank.

[0038] Furthermore, it may preferably be provided that the steering system has a filter device which is arranged in and / or on the return line.

[0039] 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. As a result, cost savings can also be achieved with this type of filter design.

[0040] 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.

[0041] 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.

[0042] Further details and advantages of the invention will now be explained in more detail with reference to the exemplary embodiments shown in the drawings.

[0043] Figure 1 shows a schematic representation of a circuit arrangement of an embodiment of a steering system;

[0044] Fig. 2 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0045] Fig. 3 shows a schematic sectional view of an embodiment of a valve assembly of a steering system;

[0046] Fig. 4 shows an example of the switching state of the valve device according to Fig. 3;

[0047] Fig. 5 shows a schematic sectional view of another embodiment of a valve assembly of a steering system;

[0048] Fig. 6 shows an example of the switching state of the valve device according to Fig. 5;

[0049] Fig. 7 shows a schematic sectional view of another embodiment of a valve assembly of a steering system;

[0050] Fig. 8 shows an example of the switching state of the valve device according to Fig. 7;

[0051] Fig. 9 shows a schematic representation of a circuit arrangement of another

[0052] Exemplary embodiment of a steering system;

[0053] Fig. 10 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0054] Fig. 11 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0055] Fig. 12 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system; Fig. 13 shows a schematic sectional view of a further embodiment of a valve assembly of a steering system;

[0056] Fig. 14 shows a schematic sectional view of another embodiment of a valve assembly of a steering system;

[0057] Fig. 15 shows an example switching state of the valve device according to Fig. 14;

[0058] Fig. 16 shows a schematic sectional view of another embodiment of a valve assembly of a steering system;

[0059] Fig. 17 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system;

[0060] Fig. 18 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system; and

[0061] Fig. 19 shows a schematic representation of a circuit arrangement of another embodiment of a steering system.

[0062] Identical or functionally equivalent elements are provided with the same reference symbols in all figures.

[0063] Fig. 1 shows a schematic representation of a circuit arrangement of an embodiment of a steering system 100.

[0064] The electro-hydraulic steering system 100 for a commercial vehicle has a steering gear 102 in the form of a spindle steering gear 102.

[0065] The screw steering gear 102 can be designed as a ball screw steering gear, although other types of gears are also conceivable. The electro-hydraulic steering system 100 further comprises a first line 104 through which the steering gear 102 can be supplied with hydraulic fluid and controlled.

[0066] 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.

[0067] 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.

[0068] The valve assembly 108 can, for example, be a respective valve assembly 108 which is described in connection with Figs. 3 to 8 and / or Figs. 13 to 16.

[0069] It is understood that all structural and functional features relating to the valve assembly 108 of Fig. 1 (and / or Fig. 2) may also be provided, alone or in combination, in the respective valve assembly 108 of Figs. 3 to 8 and / or Figs. 13 to 16, and / or vice versa, and the associated advantages may be achieved accordingly.

[0070] 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.

[0071] 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.

[0072] In other words, the steering system 100 has a hydraulic tank 110 and a return line 112 which is connected to the valve assembly 108 and the hydraulic tank 110.

[0073] The valve assembly 108 can be designed as a passively acting (low-pressure) valve assembly that is conditionally controllable by means of a pilot pressure (see Fig. 1, dashed lines). Alternatively or additionally, the valve assembly 108 can be actuated on demand, preferably partially electromagnetically, by means of a control unit not shown in the figures, which is assigned to or associated with the steering system 100.

[0074] 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.

[0075] 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.

[0076] On the other hand, the hydraulic pump 114 is connected to the first and second lines 104, 106.

[0077] 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.

[0078] 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.

[0079] 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 104 and 106.

[0080] 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 control of the direction of rotation of the hydraulic pump 114. Such control can be effected by a control unit not shown in the figures, which can be assigned to or is associated with the steering system 100.

[0081] 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.

[0082] It is also conceivable in this context that the hydraulic pump 114 is integrated into the tank.

[0083] 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.

[0084] 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.

[0085] In this case, a first check valve 118 is arranged in and / or on the first line 104.

[0086] Furthermore, a second check valve 120 is arranged in and / or on the second line 106.

[0087] As can be seen in Fig. 1, the first and second check valves 118, 120 can be arranged between the hydraulic pump 114 and the hydraulic tank 110.

[0088] 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 backflow towards the hydraulic tank 110 is prevented by the first and second check valves 118 and 120, respectively. The first check valve 118 and the second check valve 120 can serve and / or function as suction valves.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] The temperature sensor 122 and the pressure sensor 124 can be arranged between the 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 is 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 assigned 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. The pressure in the opposite second pressure chamber is lower because the steering gear 102 is connected to the return line 112 via the section of the second line 106 and the valve assembly 108.

[0101] 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.

[0102] This results in a rapid return of the hydraulic fluid, since the operating pressure in the first line 104, which is higher compared to the operating pressure in the second line 106, has caused the valve device 108 to connect the second line 106 to the return line 112.

[0103] The second line 106 can be connected to the return line 112 by means of the valve device 108, preferably by means of the passively pressure-controlled valve device 108, depending on the pressure difference between the first line 104 and the second line 106.

[0104] 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.

[0105] 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.

[0106] In the case described above, the first line 104 is therefore pressurized by the hydraulic pump 114, whereas the second line 106 is not pressurized, at least in the section between the hydraulic pump 114 and the steering gear 102 and / or valve assembly 108. 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:

[0107] 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.

[0108] During pressure build-up, the hydraulic pump 114 is supported by the first check valve 118, which acts as a suction valve.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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 fed back to the hydraulic tank 110 via the return line 112.

[0113] This results in a rapid return of the hydraulic fluid, since the operating pressure in the second line 106, which is higher compared to the operating pressure in the first line 104, has caused the valve device 108 to connect the first line 104 with the return line 112.

[0114] In a sense, the first line 104 was connected to the return line 112 by means of the valve device 108 depending on the pressure difference between the first line 104 and the second line 106, preferably by means of the passively pressure-controlled valve device 108.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] In other words, a pressure in the first or second line 104, 106 is used as a control pressure for the valve assembly 108 to enable a pressure reduction or pressure decrease in the respective other line 106, 104 and the corresponding pressure chamber, which advantageously allows for a rapid pressure relief phase in the said pressure chamber and consequently accelerates the response of the entire steering system.

[0119] 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.

[0120] 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.

[0121] Fig. 2 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 200.

[0122] 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 only the differences will be described below.

[0123] As can be seen in Fig. 2, the steering system 200 has a further check valve 202.

[0124] 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.

[0125] The additional check valve 202 advantageously enables a minimization of leakage losses, particularly with regard to the valve assembly 108, which can lead to a reduction in the maintenance effort of the steering system 200.

[0126] It is understood that the function of the steering system 200 of Fig. 2 essentially corresponds to the function of the steering system 100 of Fig. 1. However, during the operation of the steering system 200 of Fig. 2, the hydraulic fluid, starting from the valve assembly 108 and flowing downstream towards the hydraulic tank 110, must also pass through the further check valve 202.

[0127] With reference to Figs. 3 to 8, further embodiments of the valve assembly 108 will be described below, which may each 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 of Figs. 9 to 12.

[0128] Figures 3 and 4 show a schematic sectional view of an embodiment of a valve assembly 108 of a steering system 100, 200.

[0129] The valve assembly 108 has a housing body 300, which can be designed, for example, as a single piece or in multiple parts.

[0130] A main chamber 302 is formed in the housing body 300.

[0131] 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.

[0132] The first connection 128 and the second connection 130 are arranged opposite each other with respect to the main chamber 302.

[0133] In the present embodiment, the first terminal 128 and the second terminal 130 are each formed from at least two sections. However, this is purely exemplary. For example, the aforementioned terminals 128 and 130 could also be formed from only one terminal (section).

[0134] The valve assembly 108 further comprises a first spring element 304, a second spring element 306 and a switching element 308, which are arranged in the main chamber 302.

[0135] The switching element 308 is preferably designed as a sliding element 310. The switching element 308 is formed from at least two pot-shaped sections, the respective open ends of which are oriented towards the first terminal 128 and the second terminal 130 (each assigned) and whose respective closed ends abut and / or are attached to each other and / or are integrally formed together.

[0136] The two pot-shaped sections form a sealing seal on the inside of the main chamber 302. In particular, the switching element 308, or rather the pot-shaped sections, divide the main chamber 302 into a chamber part facing the first connection 128 and a chamber part of the main chamber 302 facing the second connection 130.

[0137] The switching element 308 is arranged between the first spring element 304 and the second spring element 306.

[0138] Preferably, the first spring element 304 and the second spring element 306 have the same or identical spring constant.

[0139] The first 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 closed end of the pot-like section oriented towards the first connection 128.

[0140] The second spring element 306 is arranged with one end on the inside of the housing body 300 and with the opposite end on the inside of the closed end of the pot-like section oriented towards the second connection 130.

[0141] The valve assembly 108 also has a third connection 312, to which the return line 112 can be connected or is connected.

[0142] Furthermore, a bypass line 314 is formed in the housing body 300, which can connect the third connection 312 via a first section of the bypass line 314 to that section of the main chamber 302 which faces the first connection 128, and which can connect the third connection 312 via a second section of the bypass line 314 to that section of the main chamber 302 which faces the second connection 130.

[0143] The pot-shaped sections of the switching element 308 each have a fluid passage which can be aligned with the respective sections of the bypass line 314 to enable a fluid passage or fluid connection between the main chamber 302 and the bypass line 314.

[0144] The fluid passages can be provided in the pot-like sections of the switching element 308 as through holes, grooves or other recesses.

[0145] When the first spring element 304 and the second spring element 306 are in equilibrium, neither of the fluid passages is connected to the bypass line 314. This state is shown, for example, in Fig. 3.

[0146] When printing (according to Figs. 3 and 4: pressure P1) occurs via the first port 128, the switching element 308 is moved towards the second port 130 (see arrow above the switching element 308 in Fig. 4), thereby deflecting the first spring element 304 and compressing the second spring element 306. This state is shown, for example, in Fig. 4. In this case, the fluid passage facing the second port 130 is connected to the bypass line 314, preferably when the switching element 308 abuts a corresponding end of the main chamber. The fluid passage facing the first port 128 remains unconnected to, or blocked from, the bypass line 314. Consequently, the second port 130 is connected, or connectable, to the third port 312 via the associated fluid passage of the switching element 308 and the bypass line 314.

[0147] This can be understood in particular to mean that if the pressure (according to Figs. 3 and 4: pressure P1) applied via the first port 128 is higher than the pressure (according to Figs. 3 and 4: pressure P2) at the second port 130, the switching element 308 is moved in such a way that the second port 130 is fluidically connected to the third port 312 (see Fig. 4).

[0148] 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 (according to Figs. 3 and 4: pressure P2) is higher than the pressure at the first port 128 (according to Figs. 3 and 4: pressure P1), the switching element 308 is moved such that the first port 128 is fluidically connected to the third port 312.

[0149] By connecting the first terminal 128 to the first line 104, the second terminal 130 to the second line 106 and the third terminal 312 to the return line 112, the first line 104 and / or the second line 106 can be connected to the return line 112 or blocked with respect to the return line 112 by means of the switching element 308.

[0150] In other words, 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, and in particular the switching element 308, depending on a pressure difference between the first line 104 and / or the second line 106. Furthermore, such a connection can be locked or disconnected when the pressure in the first line 104 and the second line 106 is the same.

[0151] Figures 5 and 6 show a schematic sectional view of a further embodiment of a valve assembly 108 of a steering system 100, 200.

[0152] The valve assembly 108 of Figs. 5 and 6 is essentially designed like the valve assembly 108 of Figs. 3 and 4, so that the differences between the embodiments will be described primarily below.

[0153] The first terminal 128, the third terminal 312 and the second terminal 130 are arranged side by side on the housing body 300. In particular, the third terminal 312 is arranged between the first terminal 128 and the second terminal 130.

[0154] The switching element 308 is preferably designed as a block-like sliding element 310, which has a recess 316 on the outer surface, for example in the form of a groove.

[0155] In this case, this recess 316 takes over the function of the bypass line 314 from the previously described embodiment according to Figs. 3 and 4.

[0156] The recess or bypass 316 is arranged adjacent to or opposite the third connection 312 in equilibrium with the first spring element 304 and the second spring element 306, and preferably aligned with it, so that a fluid connection between the recess 316 and the third connection 312 is possible. This condition is shown in Fig. 5.

[0157] When pressure is applied (according to Figs. 5 and 6: pressure P1) via the first port 128, the switching element 308 is caused to move towards the second port 130, preferably until the switching element 308 abuts a corresponding end of the main chamber, thereby deflecting the first spring element 304 and compressing the second spring element 306. This state is shown, for example, in Fig. 6. Here, the recess 316 moves towards the second port 130 and is preferably (partially) aligned with it, in addition to the third port 316, so that a fluid connection between the third port 316 and the second port 130 can be established or is established via the aforementioned recess 316 (see arrow in Fig. 6). Thus, the second port 130 is connected or connectable to the third port 312 via the recess 316.

[0158] This can be understood in particular to mean that if the pressure (according to Figs. 5 and 6: pressure P1) applied via the first port 128 is higher than the pressure (according to Figs. 5 and 6: pressure P2) applied to the second port 130, the switching element 308 is moved in such a way that the second port 130 is fluidically connected to the third port 312 (see Fig. 6).

[0159] 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 to or exerted via the second port 130 is higher than the pressure at the first port 128, the switching element 308 is moved such that the first port 128 is fluidically connected to the third port 312 via the recess 316.

[0160] By connecting the first terminal 128 to the first line 104, the second terminal 130 to the second line 106 and the third terminal 312 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 316) or can be blocked or disconnected with respect to the return line 112.

[0161] In other words, depending on a pressure difference between the first line 104 and / or the second line 106, the first line 104 and / or the second line 106 can be connected to the return line 112 by means of the valve device 108, and in particular the switching element 308, and such a connection can be locked or disconnected when the pressure in the first line 104 and the second line 106 is the same.

[0162] Figures 7 and 8 show a schematic sectional view of a further embodiment of a valve assembly 108 of a steering system 100, 200.

[0163] The valve assembly 108 of Figs. 7 and 8 is essentially designed like the valve assembly 108 of Figs. 3 and 4 or Figs. 5 and 6, so that the differences between the embodiments will be described primarily below.

[0164] According to Figs. 7 and 8, the switching element 308 is designed as a piston element 318.

[0165] The switching element 308 has a central section 320, a first side section 322 and a second side section 324. In particular, the switching element 308, the central section 320, the first side section 322 and / or the second side section 324 can each be formed individually and / or together, in one piece or in multiple parts.

[0166] The central section 320 is arranged between the first side section 322 and the second side section 324 and is connected to them via web-like connections, preferably integrally connected.

[0167] The first page section 322 is assigned to the first port 128 and the second page section 324 is assigned to the second port 130.

[0168] The main chamber 302 in this case has a middle chamber 326, a first subsidiary chamber 328 and a second subsidiary chamber 330.

[0169] The central chamber 326 is arranged between the first secondary chamber 328 and the second secondary chamber 330 and is fluidically connected to the secondary chambers via openings. The openings are configured to correspond to the first and second side sections 322 and 324, respectively.

[0170] In this case, the first auxiliary chamber 328 and the second auxiliary chamber 330 are connected to the third connection 312 via the bypass line 314.

[0171] The first and second connections 128, 130 each lead into the middle chamber 326.

[0172] The switching element 308 is provided in the main chamber 302 such that the central section 320 is located in the central chamber 326, and there between the first and the second terminal 128, 130.

[0173] The first spring element 304 is arranged in the first secondary chamber 328 and connected to the first side section 322. The second spring element 306 is arranged in the second secondary chamber 330 and connected to the second side section 324.

[0174] The first side section 322 is located in the first secondary chamber 328 and in the associated opening. When printed via the second connection 130, the first side section 322 can be moved across or along the opening towards the first secondary chamber 328 and can be moved completely into it. This creates a fluid connection between the central chamber 326 and the first secondary chamber 328 via the newly available opening.

[0175] The second side section 324 is located in the second auxiliary chamber 330 and in the associated opening. When printed via the first connection 128, the second side section 324 can be moved across or along the opening towards the second auxiliary chamber 330 and can be moved completely into it. This creates a fluid connection between the central chamber 326 and the second auxiliary chamber 330 via the newly opened opening.

[0176] When the first spring element 304 and the second spring element 306 are in equilibrium, neither of the openings to the secondary chambers 328, 330 is open. In this case, the openings are tightly closed by the side sections 322, 324. This state is shown, for example, in Fig. 7.

[0177] When printing (according to Figs. 7 and 8: print P1) is applied via the first connection 128, the switching element 308 is moved towards the second auxiliary chamber 330, the first spring element 304 is deflected, and the second spring element 306 is compressed. This state is shown, for example, in Fig. 8.

[0178] The second side section 324 is moved into the second auxiliary chamber 330, and the opening in question is opened by means of the displaced or deflected second side section 324, thereby enabling fluid passage from the central chamber 326 via the second auxiliary chamber 330 to the bypass line 314. Consequently, the second port 130 is connected to the third port 312 via the central chamber 326, the second auxiliary chamber 330, and the bypass line 314.

[0179] This can be understood in particular to mean that if the pressure (according to Figs. 7 and 8: pressure P1) applied via the first port 128 is higher than the pressure (according to Figs. 7 and 8: pressure P2) applied to the second port 130, the switching element 308 is moved in such a way that the second port 130 is fluidically connected to the third port 312 or can form a fluid connection (see arrow in Fig. 8).

[0180] 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 (according to Figs. 7 and 8: pressure P2) is higher than the pressure applied to the first port 128 (according to Figs. 7 and 8: pressure P1), the switching element 308 is moved in such a way that the first port 128 is fluidically connected to the third port 312, or can form a fluid connection.

[0181] By connecting the first terminal 128 to the first line 104, the second terminal 130 to the second line 106 and the third terminal 312 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 or can be blocked or disconnected with respect to the return line 112.

[0182] In other words, depending on a pressure difference between the first line 104 and / or the second line 106, the first line 104 and / or the second line 106 can be connected to the return line 112 by means of the valve device 108 and in particular the switching element 308, and such a connection can be locked or disconnected when the pressure in the first line 104 and the second line 106 is the same.

[0183] Figure 9 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 400. The further embodiment of the steering system 400 shown in Figure 9 has essentially the same structural and functional features as the embodiment of the steering system 100 shown in Figure 1, so that the differences between the embodiments will be described primarily below.

[0184] As can be seen in Fig. 9, the steering system 400 includes a backup device, in this case designed as a backup valve device, in particular as a backup valve 402. It is understood that the representation shown in Fig. 9 is purely exemplary and that a functionally equivalent unit to the backup valve 402 could also be provided.

[0185] The backup valve 402 is connected, at least indirectly, to the first line 104 via the pressure chamber of the steering gear 102 assigned to the first line 104.

[0186] The backup valve 402, on the other hand, is connected, at least indirectly, to the second line 106 via the pressure chamber of the steering gear 102 assigned to the second line 106.

[0187] 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.

[0188] 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.

[0189] In a sense, the backup valve 402 can thus form and / or enable a fault circuit not specifically shown in the figures and / or function as such. It is understood that the function of the steering system 400 of Fig. 9 essentially corresponds to the function of the steering system 100 of Fig. 1.

[0190] 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.

[0191] 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.

[0192] It is understood that the backup device or the backup valve device, in particular the backup valve 402, can be controlled or controlled via a control unit that can be assigned to or associated with the steering system 400.

[0193] Fig. 10 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 500.

[0194] The further embodiment of the steering system 500 shown in Fig. 10 has essentially the same structural and functional features as the embodiments of the steering system 200, 400 shown in Figs. 2 and 9.

[0195] In a sense, the embodiment of the steering system 500 of Fig. 10 is a combination of the embodiments of the steering system 200, 400 of Fig. 2 and 9.

[0196] In other words, the steering system 500 of Fig. 10 includes both the backup valve 402 described above and the return line check valve 202 described above. It is understood that the function of the steering system 500 of Fig. 10 essentially corresponds to, or can combine the functionalities of, the steering system 200 of Fig. 2 and the steering system of Fig. 9.

[0197] Fig. 11 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 600.

[0198] The further embodiment of the steering system 600 shown in Fig. 11 has essentially the same structural and functional features as the embodiment of the steering system 400 shown in Fig. 9, so that the differences between the embodiments will be described primarily below.

[0199] As can be seen in Fig. 11, the steering system 600 is provided in particular without a check valve.

[0200] In other words, the steering system 600 does not have either the first or the second check valve 118, 120.

[0201] 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.

[0202] Optionally, the temperature sensor 122 and / or the pressure sensor 124 can also be provided on and / or in the intake line 116.

[0203] The steering system 600 of Fig. 11 is also provided with a backup valve 402, which is integrated into the valve assembly 108 and has the functionality described above.

[0204] Such a backup valve 402 integrated in the valve assembly 108 is shown, for example, in the exemplary embodiment of a valve assembly 108 in Fig. 16, whereby it is understood that the embodiment shown in Fig. 16 is only one possible exemplary embodiment. It is understood that the function of the steering system 600 of Fig. 11 essentially corresponds to the function of the steering system 400 of Fig. 9, 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.

[0205] It should also be understood that the steering system 600 of Fig. 11 can also be configured without a backup valve. Thus, the steering system 600 of Fig. 11 can be configured without a backup valve and / or without a check valve. In other words, the steering system 600 of Fig. 11, for example, like the steering system 100 of Fig. 1, can be configured without the two check valves 118, 120, and the associated functional support of the hydraulic pump 114 in the form of suction valves.

[0206] Fig. 12 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 700.

[0207] The further embodiment of the steering system 700 shown in Fig. 12 has essentially the same structural and functional features as the embodiment of the steering system 600 shown in Fig. 11, so that the differences between the embodiments will be described primarily below.

[0208] As can be seen in Fig. 12, the steering system 700 is also free of check valves.

[0209] The steering system 700 shown in Fig. 12 also has a backup valve 402.

[0210] 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 has already been described above in connection with Figs. 9 and 10.

[0211] It is understood that the function of the steering system 700 of Fig. 12 ultimately corresponds essentially to the function of the steering system 600 of Fig. 10, particularly with regard to the design of the backup valve 402 and the associated functionality of pressure reduction or pressure equalization through a fluid connection or a fluid short circuit, especially in the event of an emergency or fault.

[0212] Fig. 13 shows a schematic sectional view of a further embodiment of a valve assembly 108 of a steering system 100, 200, 400, 500, 600, 700.

[0213] The further embodiment of the valve device 108 shown in Fig. 13 has essentially the same structural and functional features as the embodiment of the valve device 108 shown in Figs. 5 and 6, so that the differences between the embodiments will be described primarily below.

[0214] As can be seen in Fig. 13, the state shown corresponds to the schematic representation according to Fig. 6.

[0215] Furthermore, it can be seen in Fig. 13 that the housing body 300 is provided with two further tank connections 340 for the fluid connection of the valve assembly 108 with the hydraulic tank 110.

[0216] The tank connections 340 are arranged opposite each other and open into a respective area of ​​the main chamber 302, in which the first spring element 304 and the second spring element 306 are arranged on the one hand.

[0217] In other words, the tank connections 340 are arranged on opposite sides of the housing body 300 with respect to the switching element 308.

[0218] The additional connections between the valve assembly 108 and the hydraulic tank 110 advantageously enable damped actuation of the valve assembly 108, since, for example, a pressure gradient via the first or second line 104, 106 can be flattened or reduced by the direct fluidic return of the hydraulic fluid via the tank connections 340 back into the hydraulic tank 110. A damped switching behavior of the switching element 308 can thus be provided.

[0219] Furthermore, the switching element 308 has a connection channel 802.

[0220] The connecting channel 802 extends through the switching element 308 along its longitudinal axis and thus fluidically connects both halves of the main chamber 300 formed by the switching element 308.

[0221] This further enhances and / or ensures the described damping behavior.

[0222] Furthermore, a protective function can also be provided, since a (damped) pressure reduction of the first and second lines 104, 106 can always be guaranteed. In this sense, the connecting channel 802 can perform a safety function, comparable to the design or provision of a backup valve in such a steering system.

[0223] The present valve assembly 108 can therefore represent a reliable and / or safe valve assembly 108 with damping.

[0224] Figures 14 and 15 show a schematic sectional view of a further embodiment of a valve assembly 108 of a steering system.

[0225] The further embodiment of the valve assembly 108 shown in Figs. 14 and 15 has essentially the same structural and functional features as the one shown in Fig.

[0226] The embodiment of the valve device 108 shown in Fig. 5 and / or Fig. 13 is described below, so that the differences between the embodiments will be described primarily below.

[0227] As can be seen in Figures 14 and 15, the switching element 308 also has a connecting channel 802, which has already been described above in connection with Figure 13. The embodiment of the valve assembly 108 shown in Figures 14 and 15 is free of further tank connections 340.

[0228] The switching element 308 is further equipped with sealing elements 804.

[0229] The sealing elements 804 are arranged on opposite sides of the switching element 308 and surround the first and second spring elements 304 and 306 respectively in the circumferential direction.

[0230] By means of the sealing elements 804, a reliable seal between the switching element 308 and the outer surface, in particular corresponding stop surfaces, of the main chamber 302 can be provided, especially in the respective switching states of the switching element 308 when pressurized via the first or the second line 104, 106.

[0231] It is understood that the function of the valve assembly 108 of Figs. 14 and 15 essentially corresponds to the function of the valve assembly 108 of Fig. 13 (but without the damping characteristic described there).

[0232] Furthermore, it is understood that, for example, the valve devices 108 according to Figs. 13 to 15 may be provided in one of the steering systems described.

[0233] Fig. 16 shows a schematic sectional view of a further embodiment of a valve assembly 108 of a steering system 100, 200, 400, 500, 600, 700.

[0234] The valve assembly 108 shown in Fig. 16 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. 16 can, for example, be the valve assembly 108 shown in Fig. 11.

[0235] The further embodiment of the valve device 108 shown in Fig. 16 has essentially the same structural and functional features as the embodiment of the valve device 108 shown in Figs. 5 and 6, so that the differences between the embodiments will be described primarily below.

[0236] As can be seen in Fig. 9, the backup valve 402 is integrated into the housing body 300.

[0237] The backup valve 402 has a slide 806, a preload element 808, an electromagnet 810 and a chamber 812.

[0238] The slide 806 is located in chamber 812.

[0239] The chamber 812 of the backup valve 812 can be connected to the main chamber 302 of the valve assembly 108 via two fluid passages.

[0240] 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 812.

[0241] 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 812.

[0242] The slide 806 is connected to the electromagnet 810, in particular operatively connected.

[0243] By means of the electromagnet 810, the slide 806 can be moved across a respective fluid passage – according to an actuation of the electromagnet 810 by a control unit assigned to or associated with the steering system – thereby allowing the passage to be selectively closed and / or opened. The preload element 808 provided in the backup valve 402 tensions the slide 806 in this case towards the fluid passage that is assigned to the second port 130. In Fig. 16, the preload element 808, which can be a spring element, is compressed. In other words, the electromagnet 810 is actuated such that the other fluid passage is closed by the slide 806.

[0244] As can be seen in Fig. 16, the slide 806 also has a connecting channel 814 which extends through the slide 806 along a longitudinal axis.

[0245] This can be understood in particular to mean that if the slide 806 does not cover any of the said fluid passages, i.e., is arranged between the fluid passages, the said fluid passages are fluidically connected to each other.

[0246] 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 812 and the connecting channel 814.

[0247] In this way, the first and second lines 104, 106 can be connected to each other and, in particular, short-circuited.

[0248] 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.

[0249] 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.

[0250] By means of the backup valve 402, the first and second lines 104, 106 and the respective pressure chambers of the steering gear 102 can be connected to each other and preferably short-circuited.

[0251] This can further improve the safety and / or reliability of the steering system, as the two lines 104, 106 and the pressure chambers of the steering gear 102 can be connected in an emergency situation, thus ensuring a corresponding pressure reduction and the associated steerability or steering function at all times.

[0252] In particular, in an emergency, a short circuit of the pressure chambers of the steering gear 102 can be caused or initiated by the backup valve 402 (by allowing both of the described fluid passages to be opened by the slide valve 806), so that a corresponding pressure reduction and consequently steering can always be guaranteed even in such an emergency or fault situation.

[0253] In an emergency, the backup valve 402 can move from its closed position (see Fig. 16) to a flow position (arrangement of the slide 806 between the fluid passages) to enable such a short circuit.

[0254] Fig. 17 shows a schematic representation of a circuit arrangement of a further embodiment of a steering system 800.

[0255] The further embodiment of the steering system 800 shown in Fig. 17 has essentially the same structural and functional features as the embodiment of the steering system 500 shown in Fig. 10, so that the differences between the embodiments will be described primarily below.

[0256] As can be seen in Fig. 17, the steering system 800 has a filter device 816.

[0257] The filter device 816 is arranged in the return line 112.

[0258] In particular, the filter device 816 is arranged between the return line check valve 202 and the hydraulic tank 110.

[0259] This arrangement has the advantage that the filter or filter assembly 816 does not need 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. Consequently, the filter or filter assembly 816 can be designed to be mechanically less robust and structurally simpler, since it is not subjected to such high pressures.

[0260] As shown in Fig. 17, 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.

[0261] Consequently, cost advantages can also be realized through such a design of the filter or filter device 816.

[0262] Fig. 18 shows a schematic representation of a (circuit) arrangement of a further embodiment of a steering system 1100.

[0263] Compared to the embodiment in Fig. 17, the steering system 900 according to Fig. 18 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. 18, and in contrast to Fig. 17, it may be provided that no check valve 202 (cf. Fig. 17) is present in the return line 112. Therefore, the following discussion will focus primarily on the aforementioned differences according to Fig. 18.

[0264] According to Fig. 18, the filter device 816 is provided in the return line 112, between the hydraulic tank 110 and the valve device 108, without an additional check valve 202.

[0265] A third check valve 204 can be arranged in the first line 104 and a fourth check valve 206 in the second line 106, particularly 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. Two check valves 118, 120, 204, 206 can each be arranged in the first and second lines 104 and 106, so that, depending on the direction of rotation or delivery of the hydraulic pump 114, controlled suction of hydraulic fluid from the hydraulic tank 110 is possible.

[0266] 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.

[0267] Figure 19 shows a schematic representation of a (circuit) arrangement of another embodiment of a steering system 1000. The following discussion focuses primarily on the difference between the embodiment according to Figure 12 and the embodiment according to Figure 11.

[0268] In particular, as shown in Fig. 19, 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.

[0269] Preferably, the check valve 112 according to Fig. 19 is provided between the filter unit 816 and the valve assembly 108.

[0270] In particular, the return line check valve 202 can be arranged along the return line 112 in such a way that an oil flow or oil leakage from the valve assembly 108 via the filter assembly 816 is provided or enabled and an opposite backflow, i.e. via the filter assembly 816 to the valve assembly 108, can be prevented.

[0271] In summary, the present invention advantageously provides an electro-hydraulic steering system which, by means of a valve device, in particular a low-pressure valve device, 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.

[0272] Thus, both optimized hydraulic power steering and improved steering feel can be ensured for the driver of a vehicle according to the invention.

[0273] In particular, a passively pressure-controlled 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.

[0274] 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.

[0275] REFERENCE MARK LIST

[0276] 100 steering system

[0277] 102 Steering gear

[0278] 104 first line

[0279] 106 second line

[0280] 108 Valve assembly

[0281] 110 hydraulic tank

[0282] 112 Return line

[0283] 114 Hydraulic pump

[0284] 115 Leakage line

[0285] 116 Intake manifold

[0286] 118 first check valve

[0287] 120 second check valve

[0288] 122 Temperature sensor

[0289] 124 Pressure sensor

[0290] 126 Building module

[0291] 128 first connection

[0292] 130 second connection

[0293] 200 steering system

[0294] 202 Return line check valve

[0295] 204 third check valve

[0296] 206 fourth check valve

[0297] 300 housing bodies

[0298] 302 Main Chamber

[0299] 304 first spring element

[0300] 306 second spring element

[0301] 308 Switching element

[0302] 310 sliding element

[0303] 312 third connection

[0304] 314 Bypass line

[0305] 316 Exclusion

[0306] 318 Piston element 20 Center section 22 First side section 24 Second side section 26 Center chamber 28 First secondary chamber 30 Second secondary chamber 40 Tank connection 00 Steering system 02 Backup valve 00 Steering system 00 Steering system 00 Steering system 00 Steering system 02 Connecting channel 04 Sealing element 06 Slide

[0307] 808 Preload element

[0308] 810 Electromagnet

[0309] 812 Chamber

[0310] 814 Connection channel

[0311] 816 Filter unit

[0312] 900 steering system

[0313] 1000 steering system

Claims

PATENT CLAIMS 1. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) 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 assembly (108) connected or connectable to the first line (104) and / or the second line (106), in particular a low-pressure valve assembly, for pressure reduction in the first line (104) and / or the second line (106).

2. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) according to claim 1 , characterized in that the steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) 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; 1000) according to claim 2, characterized in that the steering system (200; 500) 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; 900; 1000) 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; 900; 1000) 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; 900; 1000) according to one of the preceding claims, characterized in that the first line (104) and / or the second line (106) can be blocked with respect to the return line (112) by means of the valve device (108) depending on an equal pressure in the first line (104) and / or the second line (106).

7. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) according to one of the preceding claims, characterized in that the valve assembly (108) has at least one first and one second spring element (304, 306) and at least one switching element (308) arranged between the first and the second spring element (304, 306).

8. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) 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) or can be locked with respect to the return line (112).

9. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) according to claim 7 or 8, characterized in that the switching element (308) can be tensioned into a starting position by means of the first and the second spring element (304, 306) in which the first line (104) and the second line (106) are blocked with respect to the return line (112).

10. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) according to one of claims 7 to 9, characterized in that the switching element (308) is designed as a sliding element (310) and / or has such a, or the switching element (308) is designed as a piston element (318) and / or has such a.

11. Electro-hydraulic steering system (400; 500; 600; 700; 800; 900; 1000) according to one of the preceding claims, characterized in that the steering system (400; 500; 600; 700) 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; 900; 1000) according to one of the preceding claims, characterized in that at least one first check valve (118) is arranged in the first line (104) and / or at least one second check valve (120) is arranged in the second line (106).

13. Electro-hydraulic steering system (100; 200; 400; 500; 600; 700; 800; 900; 1000) according to one of the preceding claims, characterized in that the steering system (100; 200; 400; 500; 600; 700) 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; 900; 1000) 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; 900; 1000) according to one of the preceding claims.

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