Steering System for a Vehicle, in Particular a Utility Vehicle

Abstract

A steering system for a vehicle, in particular a utility vehicle, has at least one steering transmission, in particular a ball nut hydraulic steering transmission; at least one steering mechanism for steering at least one first vehicle wheel and for steering at least one second vehicle wheel, wherein the steering transmission is coupled to the steering mechanism; at least one hydraulic pump for supplying the steering transmission with hydraulic fluid; and at least one drive motor which is provided independently and/or separately from the traction drive of the vehicle and which is coupled to the hydraulic pump in order to drive same. In the assembled state, the steering transmission, the hydraulic pump, and the drive motor are designed as a unit.

Claims

1.-12. (canceled)

13. A steering system for a utility vehicle, comprising: at least one steering gear; at least one steering mechanism for steering at least one first vehicle wheel and for steering at least one second vehicle wheel, wherein the steering gear is coupled to the steering mechanism; at least one hydraulic pump for supplying the steering gear with hydraulic fluid; and at least one drive motor which is provided independently of and/or separately from a traction drive of the vehicle and which is coupled to the hydraulic pump in order to drive the hydraulic pump, wherein, in a mounted state, the steering gear, the hydraulic pump, and the drive motor are configured as a structural unit.

14. The steering system according to claim 13, wherein the steering gear is a ball-and-nut power steering gear.

15. The steering system according to claim 13, wherein the drive motor is coupled to the hydraulic pump directly without a clutch.

16. The steering system according to claim 15, wherein the drive motor and the hydraulic pump have at least one common drive shaft.

17. The steering system according to claim 16, wherein the steering system has at least one first shaft bearing device and at least one second shaft bearing device, via which the drive shaft is at least partly supported in the mounted state.

18. The steering system according to claim 17, wherein the first shaft bearing device and the second shaft bearing device form a hybrid bearing system.

19. The steering system according to claim 17, wherein in the mounted state, the first shaft bearing device is arranged on the drive shaft between the drive motor and the hydraulic pump.

20. The steering system according to claim 17, wherein the first shaft bearing device is configured as a double-row grooved ball bearing.

21. The steering system according to claim 17, wherein the drive shaft has an axial end which, in the mounted state, protrudes from a side of the hydraulic pump facing away from the drive motor, and the second shaft bearing device is arranged at said axial end of the drive shaft.

22. The steering system according to claim 17, wherein the second shaft bearing device is a hydrodynamic plain bearing.

23. The steering system according to claim 16, wherein the drive shaft has a motor shaft portion in a region of the drive motor and a pump shaft portion in a region of the hydraulic pump, and the motor shaft portion has a greater diameter than the pump shaft portion.

24. The steering system according to claim 13, wherein the drive motor is an electric motor.

25. The steering system according to claim 13, wherein the hydraulic pump is a bidirectional hydraulic pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a schematic, perspective illustration of a steering system from the prior art;

[0026] FIG. 2a is a first schematic block diagram of an exemplary embodiment of a steering system according to the invention; and

[0027] FIG. 2b is a second schematic block diagram of the exemplary embodiment of the steering system according to the invention from FIG. 2a.

DETAILED DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows a schematic, perspective illustration of a steering system 10 from the prior art. The steering system 10 substantially consists of a steering gear (transmission) 12 in the form of a ball-and-nut power steering gear, and a steering mechanism 14 coupled therewith for steering the two vehicle wheels (not shown in FIG. 1).

[0029] The steering mechanism has a first and second steering rod 14a, 14b and a first and second track rod 14c, 14d.

[0030] According to FIG. 1, the first steering rod 14a and the first track rod 14c are connected in articulated fashion to a first wheel carrier for steering or pivoting thereof, wherein the first steering rod 14a is coupled to an output shaft of the steering gear 12.

[0031] The second steering rod 14b is in turn hinge-mounted via a pusher on the first wheel carrier, and thus couples in articulated fashion the first wheel carrier to the second wheel carrier via the pusher and the second track rod 14d.

[0032] Furthermore, the steering system 10 has a hydraulic pump 16 which is coupled via pipework 16a to the steering gear 12 in order to supply hydraulic fluid thereto.

[0033] An expansion tank 16b is arranged in the pipework 16a between the hydraulic output of the steering gear 12 and the input of the hydraulic pump 16.

[0034] Also, the steering system according to FIG. 1 contains a steering column 17 in the form of a multi-element linkage, and a steering wheel 17a rotationally fixedly coupled thereto for manual control of the steering gear 12, which leads to a pivoting of the steering mechanism 14 and hence steering of the vehicle wheels.

[0035] FIG. 2a shows a first schematic block diagram of an exemplary embodiment of a steering system 110 according to the invention.

[0036] Components of the steering system 110 according to the invention, which are the same or similar to those of the steering system 10 from FIG. 1 according to the prior art, carry a respective reference number increased by 100.

[0037] The steering system 110 for a vehicle according to FIG. 2a has a steering gear (transmission) 112. The steering gear 112 is configured as a ball-and-nut power steering gear and the vehicle is accordingly configured as a utility vehicle.

[0038] Furthermore, the steering system 110 has a first steering mechanism 114 for steering a first vehicle wheel and for steering a second vehicle wheel.

[0039] FIG. 2a shows schematically only the first steering rod 114a, as representative of the steering mechanism 114, which rod is coupled rotationally fixedly to an output shaft 112a of the steering gear 112.

[0040] The steering gear 112 is thus coupled to the steering mechanism 114 via the first steering rod 114a.

[0041] The steering system 110 also comprises a hydraulic pump 116 for supplying hydraulic fluid to the steering gear 112.

[0042] The hydraulic pump 116 is configured as a bidirectional hydraulic pump 116.

[0043] In this case, bidirectional means that the hydraulic pump 116 can switch the pressure and suction sides by switching its rotational direction (via the drive motor 118) and thus reverse a hydraulic flow according to the steering direction.

[0044] This reversed hydraulic flow then loads the double-action steering cylinder inside the steering gear according to the required or controlled steering movement.

[0045] Also, a drive motor 118 is provided which is independent of the traction drive of the vehicle and arranged separately, and which is coupled to the hydraulic pump 116 for driving this.

[0046] According to the fundamental concept of the invention, in mounted state, the steering gear 112, the hydraulic pump 116 and the drive motor 118 are configured as a common structural unit 120.

[0047] Further ancillaries such as e.g. an expansion tank for the hydraulic pump 116, or control and regulation units of the drive motor 118, may also be integrated in the structural unit 120 but are not shown in FIG. 2a.

[0048] It may furthermore be provided that the hydraulic pump 116 and the drive motor 118 are configured as a preassembled common motor-pump unit 120a and flanged to the end face of the steering gear 112 in order to form a structural unit 120.

[0049] The motor-pump unit 120a may here in particular be flanged to the steering gear 112 at the end face opposite a mechanical through-drive 112b in order to form a mechanical coupling to a steering column.

[0050] Alternatively, it is also contemplated that the motor-pump unit 120a may be flanged to the end face of the steering gear 112 in the region of the mechanical through-drive 112b.

[0051] Alternatively, the motor-pump unit 120a may also be flanged to an outside of the steering gear 112 in its axial extent.

[0052] As further evident from FIG. 2a, no hydraulic lines or additional hydraulic switching valves are shown; only the mechanical through-drive 112b for mechanical coupling to a steering column is illustrated.

[0053] FIG. 2b shows a second schematic block diagram of the exemplary embodiment of the steering system according to the invention from FIG. 2a.

[0054] This essentially shows the motor-pump unit which substantially consists of the hydraulic pump 116 and drive motor 118.

[0055] The drive motor 118 is here coupled directly to the hydraulic pump 116.

[0056] In this context, direct may mean that the drive motor 118 and hydraulic pump 116 are connected together rotationally fixedly without intermediate components.

[0057] No clutch is thus provided.

[0058] Furthermore, in this context of direct coupling, it should be pointed out that the drive motor 118 and hydraulic pump 116 have a common drive shaft 122 for direct coupling.

[0059] The drive shaft 122 extends axially from the drive motor 118 up to the hydraulic pump 160, where in mounted state it protrudes axially from the hydraulic pump 116 in the direction of the steering gear 112.

[0060] The drive motor 118 is configured as an electric motor and has a rotor 118a, which is rotationally fixedly coupled to the drive shaft 122, and a stator 118b.

[0061] The steering system 110, and in particular the motor-pump unit 120a, furthermore comprises a first shaft bearing device 124 and a second shaft bearing device 126.

[0062] In mounted state, the drive shaft is at least partially mounted via the first and second shaft bearing devices 124, 126.

[0063] In addition, the drive motor 118 and hydraulic pump 116 may have further bearing devices (not shown in FIG. 2b) in their respective housings.

[0064] According to FIG. 2b, in mounted state, the first shaft bearing device 124 is arranged on the drive shaft 122 between the drive motor 118 and the hydraulic pump 116.

[0065] It is provided here that the first shaft bearing device 124 is arranged axially closer to the drive motor 118 than to the hydraulic pump 116.

[0066] It is also contemplated in this connection that the first shaft bearing device 124 is flanged directly to the housing of the drive motor 118 through a cover, or the first shaft bearing device 124 is directly mounted in the housing of the drive motor 118.

[0067] Additionally or alternatively, it may be provided that the drive motor 118 and the hydraulic pump 116 are coupled together by a flange (not shown in FIG. 2b), and the first shaft bearing device 124 is received by or mounted via the flange.

[0068] The first shaft bearing device 124 is configured as a grooved ball bearing.

[0069] Particularly advantageously, the grooved ball bearing may itself be configured as a double-row grooved ball bearing.

[0070] As described above, the drive shaft 122 has an axial end 122a which, in mounted state, protrudes from a side of the hydraulic pump 116 facing away from the drive motor 118.

[0071] The second shaft bearing device 126 is arranged at this axial end 122a.

[0072] The second shaft bearing device 126 may be arranged on or flanged directly onto the housing of the hydraulic pump 116, or have a defined axial distance from this.

[0073] It is also contemplated that the second shaft bearing device 126 is flanged to the hydraulic pump 116 via a cover, or is a direct component of the housing of the hydraulic pump 116.

[0074] The second shaft bearing device 126 is configured as a hydrodynamic plain bearing.

[0075] The first and second shaft bearing devices 124, 126 thus form a hybrid bearing system.

[0076] A hybrid bearing system means that the first and second shaft bearing devices 124, 126 differ in their respective bearing concepts or bearing designs.

[0077] The hybrid bearing system of a double-row grooved ball bearing and a hydrodynamic plain bearing is thus merely exemplary, so other hybrid bearing designs are also possible.

[0078] Other roller bearing forms may also be used, such as cylinder roller bearings, needle roller bearings, tapered roller bearings, spherical roller bearings or toroidal roller bearings.

[0079] The same applies to the plain bearing, where here for example a hydrostatic plain bearing would also be conceivable.

[0080] Bearing materials for the plain bearing bush may include bronze (copper-tin alloy), white metal (lead-tin alloy), lead-alloy bearing metals, aluminum alloys, plastics (e.g. PTFE), ceramics (also possibly fiber-reinforced), graphite or brass alloys.

[0081] As FIG. 2b also shows, the drive shaft 122 has a motor shaft portion 122b in the region of the drive motor 118, and a pump shaft portion 122c in the region of the hydraulic pump.

[0082] The motor shaft portion 122b has a greater diameter than the pump shaft portion 122c.

[0083] According to FIG. 2b, the first shaft bearing device 124 is also mounted on a shaft portion which corresponds to the diameter of the pump shaft portion 122c.

[0084] Alternatively, the first shaft bearing device 124 may be mounted on a shaft portion which corresponds to the diameter of the motor shaft portion 122b or a diameter between the two diameters.

[0085] According to FIG. 2b, the drive shaft 122 is shown schematically as single-step shaft, wherein the drive shaft 122 may also have multiple steps or shaft shoulders.

LIST OF REFERENCE SIGNS

[0086] 10 Steering system [0087] 12 Steering gear (transmission) [0088] 14 Steering mechanism [0089] 14a First steering rod [0090] 14b Second steering rod [0091] 14c First track rod [0092] 14d Second track rod [0093] 16 Hydraulic pump [0094] 16a Pipework [0095] 16b Expansion tank [0096] 17 Steering column [0097] 17a Steering wheel [0098] 110 Steering system [0099] 112 Steering gear [0100] 112a Output shaft of steering gear [0101] 112b Through-drive [0102] 114 Steering mechanism [0103] 114a First steering rod [0104] 116 Hydraulic pump [0105] 118 Drive motor [0106] 118a Rotor [0107] 118b Stator [0108] 120 Structural unit [0109] 120a Motor-pump unit [0110] 122 Drive shaft [0111] 122a Axial end of drive shaft [0112] 122b Motor shaft portion [0113] 122c Pump shaft portion [0114] 124 First shaft bearing device [0115] 126 Second shaft bearing device