DE102016115929A1 - Steering system and method for operating a steering system - Google Patents

Abstract

The invention relates to a steering system (1) for a motor vehicle, wherein a first hydraulic line (18) and a third hydraulic line (28) via a first OR valve (21) are merged, which by a fifth hydraulic line (43) a second hydraulic line (20) and a fourth hydraulic line (30) via a second OR valve (22) are merged, which by a sixth hydraulic line ( 44) is connected to a second pressure chamber (16) of the hydraulic cylinder (10). The invention further relates to a method for operating the steering system (1).

Description

The invention relates to a steering system for a motor vehicle. The invention further relates to a method for operating a steering system for a motor vehicle.

State of the art

In the commercial vehicle sector dominate hydraulic steering systems, which are operated by means of a hydraulic pump. This pump is driven directly by the internal combustion engine. The reason for the use of hydraulic steering systems lies in the high power required, which results from the high steering forces and large steering angles.

Due to the advancing electrification of vehicles, there are significant effects on all systems that are currently connected to the internal combustion engine. In the steering technology for commercial vehicles this is the case. The auxiliary steering pumps are driven by the internal combustion engine. Due to current considerations such as sailing functions, switching off the internal combustion engine in certain driving situations and electric driving or completely electric drive concepts new concepts for the steering are necessary.

Due to the high loads and large steering angle, which must be represented, an electrically operated steering system by means of a transmission is indeed conceivable, but its implementation is complicated from the above points, which has a negative effect on the required installation space and the cost of manufacturing.

The DE 10 2013 209 467 discloses an electrohydraulic steer-by-wire steering system including an operator interface for specifying a steering angle associated with a sensor for detecting position and / or movement of the operator interface, an electronic controller coupled to a first electro-hydraulic circuit and a second electro-hydraulic circuit and is arranged to control the two electro-hydraulic circuits in response to the signals of the sensor and a steering actuator for adjusting the steering angle of a steerable wheel having two chambers which are respectively connected in a normal operation of the steering system simultaneously with both electro-hydraulic circuits.

The invention is therefore an object of the invention to provide an improved steering system for a motor vehicle, which can be operated independently of an internal combustion engine and provides the previous requirements in terms of safety and performance, as well as autonomous driving allows.

The invention is achieved with a steering system for a motor vehicle having the features of patent claim 1. Furthermore, the object is achieved with a method for operating a steering system for a motor vehicle having the features of patent claim 10.

Disclosure of the invention

The present invention provides a steering system for a motor vehicle having a hydraulic cylinder in which a piston movable in the axial direction of the hydraulic cylinder is arranged, the hydraulic cylinder having a first and second pressure chambers separated from each other by the piston, a first reversible hydraulic pump formed thereto to provide a first volume flow of a hydraulic fluid through a first hydraulic line to the first pressure chamber or through a second hydraulic line to the second pressure chamber of the hydraulic cylinder, and a second reversible hydraulic pump, which is adapted to a second volume flow of the hydraulic fluid through a third hydraulic line to provide the first pressure chamber or by a fourth hydraulic line to the second pressure chamber of the hydraulic cylinder, wherein the first hydraulic line and the third hydraulic line via a first OR valve zusupp Ammen, which is connected by a fifth hydraulic line to the first pressure chamber of the hydraulic cylinder, and wherein the second hydraulic line and the fourth hydraulic line are merged via a second OR valve, which by a sixth hydraulic line to the second pressure chamber of the hydraulic cylinder connected is.

The present invention further provides a method of operating a steering system. The method comprises providing a hydraulic cylinder in which a piston movable in the axial direction of the hydraulic cylinder is arranged, wherein the hydraulic cylinder has a first and a second pressure chamber separated from one another by the piston.

The method further comprises providing a first reversible hydraulic pump that provides a first volume flow of hydraulic fluid through a first hydraulic line to the first pressure chamber or through a second hydraulic line to the second pressure chamber of the hydraulic cylinder.

The method further comprises providing a second reversible hydraulic pump, which provides a second volume flow of the hydraulic fluid through a third hydraulic line to the first pressure chamber or through a fourth hydraulic line to the second pressure chamber of the hydraulic cylinder, wherein the first hydraulic line and the third hydraulic line are merged via a first OR valve, which a fifth hydraulic line is connected to the first pressure chamber of the hydraulic cylinder, and wherein the second hydraulic line and the fourth hydraulic line are merged via a second OR valve, which is connected by a sixth hydraulic line to the second pressure chamber of the hydraulic cylinder.

One idea of the present invention is to achieve redundancy by merging the respective hydraulic lines of the first and second reversible hydraulic pump by means of respective OR valves, so that in the event of failure of an electric motor, a control unit or a reversible hydraulic pump of a first or second hydraulic unit each other hydraulic unit can be controlled and thus operated.

Advantageous embodiments and further developments emerge from the dependent claims and from the description with reference to the figures.

According to a preferred development, it is provided that the first reversible hydraulic pump is driven by a first electric motor and the second reversible hydraulic pump is driven by a second electric motor. By driving the respective hydraulic pump by an electric motor can account for a mechanical connection of the two electric motors by, for example, a summation gear. Thus, the number of mechanical components can be reduced advantageously.

According to a further preferred embodiment, it is provided that in an operating state of the steering system, the first reversible hydraulic pump or the second reversible hydraulic pump is operable. Due to the alternative operation of the first hydraulic pump and the second hydraulic pump, a redundancy of the steering system with simultaneous energy savings can be achieved in an advantageous manner. In order to achieve the redundancy in a normal operation thus not always both hydraulic units must be operated simultaneously. This also leads to a lower burden on the respective components.

According to a further preferred development, it is provided that a delivery volume of the first reversible hydraulic pump differs from a delivery volume of the second reversible hydraulic pump. Thus, one of the hydraulic pumps can preferably be used as a steering pump for the purpose of a straight ahead or cornering at a higher speed and the other hydraulic pump can be used as a shunting pump.

According to a further preferred embodiment, it is provided that a delivery volume of the first reversible hydraulic pump and a delivery volume of the second reversible hydraulic pump are identical. Thereby, a steering system can be provided with the largest possible number of identical parts. Thus, advantageously, the complexity of the steering system can be reduced.

According to a further preferred embodiment, it is provided that the first electric motor is connected to a first control unit, and the second electric motor is connected to a second control unit, wherein a first hydraulic unit comprises the first reversible hydraulic pump, the first electric motor and the first control unit, wherein a second hydraulic unit comprises the second reversible hydraulic pump, the second electric motor and the second control unit, and wherein the first control device and the second control device via an electrical interface to a master control unit are connectable. Due to the connectivity of the first control device and the second control device to the master control device, autonomous driving of the motor vehicle can be made possible in an advantageous manner.

According to a further preferred development, it is provided that the first control unit and the second control unit are designed to receive and process data calculated by the master control unit regarding a desired steering angle and a desired steering speed. Each of the two control units thus makes it possible to adjust the required target steering angle with the corresponding desired steering speed in an advantageous manner.

According to a further preferred embodiment, it is provided that the first hydraulic unit and the second hydraulic unit are mounted on a steering gear of the steering system. Thus, advantageously, a steering system with high integrity can be provided.

According to a further preferred embodiment, it is provided that the first hydraulic unit and the second hydraulic unit are installed separately from the steering gear in the motor vehicle. By the dissolution of the first hydraulic unit and the second hydraulic unit, the corresponding components can be flexibly installed in the vehicle.

The described embodiments and developments can be combined with each other as desired.

Further possible refinements, developments and implementations of the invention also include combinations, not explicitly mentioned, of features of the invention described above or below with regard to the exemplary embodiments.

Brief description of the drawings

The accompanying drawings are intended to provide further understanding of the embodiments of the invention. They illustrate embodiments and, together with the description, serve to explain principles and concepts of the invention.

Other embodiments and many of the stated advantages will become apparent with reference to the drawings. The illustrated elements of the drawings are not necessarily shown to scale to each other.

Show it:

1 a schematic representation of a steering system for a motor vehicle according to a preferred embodiment of the invention; and

2 a flowchart of a method for operating the steering system for the motor vehicle according to the preferred embodiment of the invention.

In the figures of the drawings, like reference characters designate like or functionally identical elements, components or components unless otherwise indicated.

1 shows a schematic representation of a steering system for a motor vehicle according to a preferred embodiment of the invention.

The steering system 1 for the motor vehicle has a hydraulic cylinder 10 on. In the hydraulic cylinder 10 is an axial direction L of the hydraulic cylinder 10 movable piston 12 arranged. The hydraulic cylinder 10 has one through the piston 12 separate first and second pressure chamber 14 . 16 on. During an axial movement of the piston 12 in the hydraulic cylinder 10 becomes a segment wave 40 by engagement of a toothing of the segment shaft 40 with a toothing of the piston 12 put in a rotary motion.

The steering system 1 further includes a first reversible hydraulic pump 17 on. The first reversible hydraulic pump 17 is adapted to a first volume flow V1 of a hydraulic fluid through a first hydraulic line 18 to the first pressure chamber 14 or by a second hydraulic line 20 to the second pressure chamber 16 of the hydraulic cylinder 10 provide. The first reversible hydraulic pump 17 moreover, it is preferably with a first oil container 3 connected. The first oil tank 3 is through a first check valve 2a with the first hydraulic line 18 connected. Furthermore, the first oil tank 3 by means of a second check valve 3b and a third check valve 2c with the second hydraulic line 20 connected.

The steering system 1 also has a second reversible hydraulic pump 27 on. the second reversible hydraulic pump 27 is adapted to a second volume flow V2 of the hydraulic fluid through a third hydraulic line 28 to the first pressure chamber 14 or by a fourth hydraulic line 30 to the second pressure chamber 16 of the hydraulic cylinder 10 provide.

The second reversible hydraulic pump 27 moreover, it is preferably with a second oil container 5 connected. The second oil tank 5 is through a fourth check valve 4a with the third hydraulic line 28 connected. Furthermore, the second oil tank 5 by means of a fifth check valve 4b and a sixth check valve 4c with the fourth hydraulic line 30 connected.

Alternatively, for example, instead of the first and second oil tank 4 . 5 a (in 1 not shown) may be provided, which with the first and second reversible hydraulic pump 17 . 27 connected is.

The first hydraulic line 18 and the third hydraulic line 28 are via a first OR valve 21 merged. The first OR valve 21 is through a fifth hydraulic pipe 43 with the first pressure chamber 14 of the hydraulic cylinder 10 connected. The second hydraulic line 20 and the fourth hydraulic line 30 are via a second OR valve 22 merged. The second OR valve 22 is through a sixth hydraulic line 44 with the second pressure chamber 16 of the hydraulic cylinder 10 connected.

The first reversible hydraulic pump 17 is preferably from a first electric motor 31 and the second reversible hydraulic pump 27 from a second electric motor 32 driven. Alternatively, another suitable number of electric motors may be provided.

In an operating state of the steering system 1 is the first reversible hydraulic pump 17 or the second reversible hydraulic pump 27 operated. Alternatively, for example, both pumps can be operated simultaneously.

A delivery volume F1 of the first reversible hydraulic pump 17 differs preferably from a delivery volume F2 of the second reversible hydraulic pump 27 ,

Alternatively, the delivery volume F1 of the first reversible hydraulic pump 17 and the delivery volume F2 of the second reversible hydraulic pump 27 for example, be identical.

The first electric motor 31 is preferably with a first controller 33 connected. The second electric motor 32 is preferably with a second controller 34 connected.

A first hydraulic unit 45 preferably has the first reversible hydraulic pump 17 , the first electric motor 31 and the first controller 33 on. A second hydraulic unit 46 preferably has the second reversible hydraulic pump 27 , the second electric motor 32 and the second controller 34 on.

The first controller 33 and the second controller 34 are preferably via an electrical interface with a master controller 36 connectable. The master controller 36 is preferably not part of the steering system. Alternatively, the master controller 36 for example, be part of the steering system.

Further alternatively, instead of providing the master controller 36 for example, the first controller 33 or the second controller 34 have the function of the master controller or operated as such.

The steering system 1 further includes one on a steering shaft 42 arranged torque sensor 41 on. The torque sensor 41 is preferably adapted to a torque signal to the first control device 33 and to the second controller 34 provide. The first controller 33 and the second controller 34 are preferably adapted to be from the master controller 36 which may alternatively be configured in the form of the first or second control unit to receive and process calculated data relating to a desired steering angle and a target steering speed.

A first hydraulic unit 45 and a second hydraulic unit 46 are preferably on a steering gear 39 of the steering system 1 grown. Alternatively, for example, only the first hydraulic unit 45 or the second hydraulic unit 46 on the steering gear 39 of the steering system 1 be grown.

The first hydraulic unit 45 and the second hydraulic unit 46 Alternatively, for example, separate from the steering gear 39 be installed in the vehicle.

2 shows a flowchart of a method for operating the steering system for the motor vehicle according to the preferred embodiment of the invention.

The present invention further provides a method of operating a steering system. The method comprises providing S1 a hydraulic cylinder in which a piston movable in the axial direction of the hydraulic cylinder is arranged, the hydraulic cylinder having a first and a second pressure chamber separated from one another by the piston. The method further comprises providing S2 a first reversible hydraulic pump that provides a first volume flow of a hydraulic fluid through a first hydraulic line to the first pressure chamber or through a second hydraulic line to the second pressure chamber of the hydraulic cylinder.

The method further comprises providing S3 a second reversible hydraulic pump which provides a second volume flow of the hydraulic fluid to the first pressure chamber through a third hydraulic line or to the second pressure chamber of the hydraulic cylinder through a fourth hydraulic line, the first hydraulic line and the third hydraulic line Line via a first OR valve, which is connected by a fifth hydraulic line to the first pressure chamber of the hydraulic cylinder, and wherein the second hydraulic line and the fourth hydraulic line are merged via a second OR valve, which by a sixth hydraulic Line is connected to the second pressure chamber of the hydraulic cylinder.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto but is modifiable in a variety of ways. In particular, the invention can be varied or modified in many ways without deviating from the gist of the invention.

For example, an arrangement, number and performance of the installed components can be adapted to appropriate requirements of the steering system.

LIST OF REFERENCE NUMBERS

1

 steering system

2a

first check valve

2 B

second check valve

2c

third check valve

3

 oilcontainer

4a

fourth check valve

4b

fifth check valve

4c

sixth check valve

5

 oilcontainer

10

hydraulic cylinders

12

piston

14

first pressure chamber

16

second pressure chamber

17

first reversible hydraulic pump

18

first hydraulic line

20

second hydraulic line

21

first OR valve

22

second OR valve

27

second reversible hydraulic pump

28

third hydraulic line

30

fourth hydraulic line

31

first electric motor

32

second electric motor

33

first control unit

34

second control unit

35a, 35b

electrical interface

36

Master controller

39

steering gear

40

sector shaft

41

torque sensor

42

steering shaft

43

fifth hydraulic line

44

sixth hydraulic line

45

first hydraulic unit

46

second hydraulic unit

F1, F2

delivery

L

axially

V1

first volume flow

V2

second volume flow

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013209467 [0005]

Claims (10)

Steering system ( 1 ) for a motor vehicle, comprising: a hydraulic cylinder ( 10 ) in which one in the axial direction (L) of the hydraulic cylinder ( 10 ) movable piston ( 12 ) is arranged, wherein the hydraulic cylinder ( 10 ) one through the piston ( 12 ) separate first and second pressure chamber ( 14 . 16 ) having; a first reversible hydraulic pump ( 17 ), which is adapted to a first volume flow (V1) of a hydraulic fluid through a first hydraulic line ( 18 ) to the first pressure chamber ( 14 ) or by a second hydraulic line ( 20 ) to the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ) to provide; and a second reversible hydraulic pump ( 27 ), which is adapted to a second volume flow (V2) of the hydraulic fluid through a third hydraulic line ( 28 ) to the first pressure chamber ( 14 ) or through a fourth hydraulic line ( 30 ) to the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ), characterized in that the first hydraulic line ( 18 ) and the third hydraulic line ( 28 ) via a first OR valve ( 21 ) which are connected by a fifth hydraulic line ( 43 ) with the first pressure chamber ( 14 ) of the hydraulic cylinder ( 10 ), and wherein the second hydraulic line ( 20 ) and the fourth hydraulic line ( 30 ) via a second OR valve ( 22 ), which by a sixth hydraulic line ( 44 ) with the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ) connected is. Steering system according to claim 1, characterized in that the first reversible hydraulic pump ( 17 ) of a first electric motor ( 31 ) and the second reversible hydraulic pump ( 27 ) of a second electric motor ( 32 ) are driven. Steering system according to claim 1 or 2, characterized in that in an operating state of the steering system ( 1 ) the first reversible hydraulic pump ( 17 ) or the second reversible hydraulic pump ( 27 ) is operable. Steering system according to one of the preceding claims, characterized in that a delivery volume (F1) of the first reversible hydraulic pump ( 17 ) from a delivery volume (F2) of the second reversible hydraulic pump (F2) 27 ) is different. Steering system according to one of claims 1 to 3, characterized in that a delivery volume (F1) of the first reversible hydraulic pump ( 17 ) and a delivery volume (F2) of the second reversible hydraulic pump ( 27 ) are identical. Steering system according to one of claims 2 to 5, characterized in that the first electric motor ( 31 ) with a first control device ( 33 ), and the second electric motor ( 32 ) with a second control device ( 34 ), wherein a first hydraulic unit ( 45 ) the first reversible hydraulic pump ( 17 ), the first electric motor ( 31 ) and the first control device ( 33 ), wherein a second hydraulic unit ( 46 ) the second reversible hydraulic pump ( 27 ), the second electric motor ( 32 ) and the second control device ( 34 ), and wherein the first control device ( 33 ) and the second control device ( 34 ) via an electrical interface ( 35a . 35b ) with a master control unit ( 36 ) are connectable. Steering system according to claim 6, characterized in that the first control unit ( 33 ) and the second control device ( 34 ) are adapted to be controlled by the master control unit ( 36 ) to receive and process calculated data concerning a target steering angle and a target steering speed. Steering system according to claim 6 or 7, characterized in that the first hydraulic unit ( 45 ) and the second hydraulic unit ( 46 ) on a steering gear ( 39 ) of the steering system ( 1 ) are grown. Steering system according to claim 6 or 7, characterized in that the first hydraulic unit ( 45 ) and the second hydraulic unit ( 46 ) separated from the steering gear ( 39 ) are installed in the motor vehicle. Method for operating a steering system for a motor vehicle, comprising the steps of: providing (S1) a hydraulic cylinder ( 10 ) in which one in the axial direction (L) of the hydraulic cylinder ( 10 ) movable piston ( 12 ) is arranged, wherein the hydraulic cylinder ( 10 ) one through the piston ( 12 ) separate first and second pressure chamber ( 14 . 16 ) having; Providing (S2) a first reversible hydraulic pump ( 17 ), which a first volume flow (V1) of a hydraulic fluid through a first hydraulic line ( 18 ) to the first pressure chamber ( 14 ) or by a second hydraulic line ( 20 ) to the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ) provides; and providing (S3) a second reversible hydraulic pump ( 27 ), which a second volume flow (V2) of the hydraulic fluid through a third hydraulic line ( 28 ) to the first pressure chamber ( 14 ) or through a fourth hydraulic line ( 30 ) to the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ), characterized in that the first hydraulic line ( 18 ) and the third hydraulic line ( 28 ) via a first OR valve ( 21 ) are merged (S4), which by a fifth hydraulic line ( 43 ) with the first pressure chamber ( 14 ) of the hydraulic cylinder ( 10 ), and wherein the second hydraulic line ( 20 ) and the fourth hydraulic line ( 30 ) via a second OR valve ( 22 ) are brought together (S5), which by a sixth hydraulic line ( 44 ) with the second pressure chamber ( 16 ) of the hydraulic cylinder ( 10 ) connected is.

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