Patent Publication Number: US-2022219753-A1

Title: Redundant steering system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to German Utility Model Application No. 20 2021 100 068.6, entitled “REDUNDANT STEERING SYSTEM”, and filed on Jan. 8, 2021. The entire contents of the above-listed application is hereby incorporated by reference for all purposes. 
     TECHNICAL FIELD 
     The present disclosure relates to a redundant steering system, such as for use in motor vehicles. 
     BACKGROUND AND SUMMARY 
     According to Regulation No 79 of the Economic Commission for Europe of the United Nations (UN/ECE) (Uniform provisions concerning the approval of vehicles with regard to steering equipment [2018/1947]) a redundant steering system is provided in vehicles to ensure steering capability in case of the axle hydraulic and main steering system malfunctioning. 
     To provide such a fallback option in the event of degradation of the primary steering system, typically an external secondary device is installed in the steering axle. However, this can lead to compatibility problems and can result in high production and/or assembly costs. 
     Therefore, the objective technical problem of the present disclosure is to propose an improved or alternative steering system which provides redundancies and which may be easy to manufacture and/or assemble. 
     This objective technical problem is solved by a redundant steering system. Further embodiments may be deduced from the other features described in the detailed description. 
     The redundant steering system includes, in one example, a first steering knuckle rotatable with respect to a first steering axis, a first steering cylinder, a first steering rod coupled to the first steering cylinder, a second steering cylinder, a second steering rod coupled to the second steering cylinder, wherein the first steering rod and the second steering rod are each rotatably coupled to the first steering knuckle at a distance from the first steering axis and at different positions along the first steering axis. 
     The arrangement of the first steering rod and the second steering rod at a distance from the first steering axis may facilitate an assembly and/or may facilitate maintenance or replacement of defective parts. 
     The first steering rod may be coupled to the first steering knuckle at a first coupling position x 1  and the second steering rod may be coupled to the first steering knuckle at a second coupling position x 2 . The first coupling position x 1  and the second coupling position x 2  may be disposed at the same distance from the first steering axis. The first coupling position x 1  and the second coupling position x 2  may be both disposed on a first coupling axis. The first coupling axis may be parallel to the first steering axis. 
     The length of the first and the second steering rod may be equal. 
     The distance between the first coupling position x 1  and the first steering axis may be a minimal distance. The distance may be measured along a straight line between the steering axis and a coupling axis, the line being perpendicular to the first steering axis and/or the first coupling axis. 
     The distance between the second coupling position x 2  and the first steering axis may be a minimal distance. The distance may be measured along a straight line between the steering axis and a coupling axis, the line being perpendicular to the first steering axis and/or the first coupling axis. 
     The redundant steering system may include a first lever portion fixedly connected to the first steering knuckle and a second lever portion fixedly connected to the first steering knuckle, wherein the first steering rod is coupled to the first steering knuckle via the first lever portion and wherein the second steering rod is coupled to the first steering knuckle via the second lever portion. 
     A first end portion of the first lever portion may be rotatably connected with the first steering rod and a second end portion of the first lever portion may be fixedly connected to the first steering knuckle. A first end portion of the second lever portion may be rotatably connected with the second steering rod and a second end portion of the second lever portion may be fixedly connected to the first steering knuckle. A distance between the first end portions of the first and the second lever portion along a direction parallel to the first steering axis may be larger than a distance between the second end portions of the first and the second lever portion along a direction parallel to the first steering axis. 
     A section of one of the lever portions extending between the end portions of said lever portion may extend perpendicular to the first steering axis. 
     The distance between the first coupling position x 1  and the first steering axis may be measured along the section of the first lever portion. The distance between the first coupling position x 1  and the first steering axis may be a minimal distance. 
     The distance between the second coupling position x 2  and the first steering axis may be measured along the section of the second lever portion. The distance between the second coupling position x 2  and the first steering axis may be a minimal distance. 
     The arrangement of the first steering rod and the second steering rod at a distance from the first steering axis may be advantageous to reduce a steering force to be provided by the steering cylinder. 
     The first steering rod may have an active area and the first steering cylinder may be configured to actuate the first steering rod via the active area of the first steering rod, wherein the second steering rod may have an active area and the second steering cylinder may be configured to actuate the second steering rod via the active area of the second steering rod, wherein the active area of the first steering rod and the active area of the second steering rod may be of equal size. 
     In one embodiment, at least one of the first steering rod and the second steering rod has an adjustable length. In one embodiment, the first steering cylinder and/or the second steering cylinder may be configured to be driven hydraulically. The first steering cylinder and the second steering cylinder may be configured to be controlled independently of one another. The steering system may include at least one hydraulic unit. The hydraulic unit for driving the first cylinder may also be used for the second cylinder. Alternatively, each cylinder can have its own hydraulic unit. The latter may have the advantage that in case of inoperability of one hydraulic unit, steering can be ensured by the other hydraulic unit. 
     In one embodiment, the steering system may further include a second steering knuckle rotatable with respect to a second steering axis (II), a third steering rod coupled to the first steering cylinder, wherein the third steering rod may be rotatably coupled to the second steering knuckle at a distance from the second steering axis. The third steering rod may be coupled to the second steering knuckle in a third coupling position x 3 . 
     The design and/or arrangement of the third steering rod may be identical to the design and/or arrangement of the first steering rod, wherein the third steering rod is coupled to the second steering knuckle instead of the first steering knuckle. 
     The arrangement and/or design of the first steering rod and the first steering knuckle may be symmetrical to the arrangement and/or design of the third steering rod and/or the second steering knuckle. 
     The distance between the coupling position x 3  and the second steering axis may be equal to the distance between the coupling position x 1  and the first steering axis. 
     The minimal distance between the coupling point of the third steering rod to the second steering knuckle and the second steering axis may be measured along a longitudinal axis of the third lever portion. 
     In one embodiment, the first steering cylinder and the second steering cylinder may be arranged substantially parallel to each other. 
     In one embodiment, the first end portion of the first lever portion and the first end portion of the second lever portion are distanced from each other, for instance along the first coupling axis. 
     In one embodiment, the redundant steering may include a first flow generating unit such as a first hydraulic pump or a first hydraulic piston fluidly connected with the first steering cylinder for controlling the first steering cylinder, such as via a first valve unit, and a second flow generating unit such as a second hydraulic pump or a second hydraulic piston fluidly connected with the second steering cylinder for controlling the second steering cylinder, such as via a second valve unit. 
     In one embodiment, the steering system may include a steering wheel. The steering wheel may be coupled to the first flow generating unit and to the second flow generating unit. 
     While multiple embodiments of the presently proposed redundant steering system are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments. Accordingly, the drawings and the detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a perspective view of a redundant steering system. 
         FIG. 2  shows a schematic view of the redundant steering system of  FIG. 1 . 
         FIG. 3  shows a schematic view of a redundant steering system with two independent valve units. 
         FIG. 1  is drawn approximately to scale. However, other relative component dimensions may be used, in other examples. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1 , a redundant steering system  1  is illustrated. The redundant steering system  1  comprises a first steering knuckle  11  rotatable with respect to a first steering axis I. Further, the redundant steering system comprises a first steering cylinder  21  and a first steering rod  31 . Further, the redundant steering system comprises a second steering cylinder  22  and a second steering rod  32 . Further, the redundant steering system comprises a second steering knuckle  12  and a third steering rod  33  rotatably coupled to the second steering knuckle  12 . The first and second steering knuckles  11 ,  12  and/or other suitable system components may be coupled to steerable wheels  35 ,  36  which are schematically depicted in  FIG. 1 . Arrows  37 ,  38  denote the connection between the drive wheels  35 ,  36  and the knuckles  11 ,  12 . It will be understood, that hubs  39  or other suitable components may enable the mechanical connection between the steerable wheels and the knuckles. 
     The first steering cylinder  21  has a first end  21 ′ that is coupled to the first steering rod  31 . The first end  21 ′ of the first steering cylinder  21  is axially movable along a longitudinal axis  23  of the first steering cylinder  21  with respect to a main body  21 ′″ of the first steering cylinder  21 . When the first steering cylinder  21  is actuated, the first end  21 ′ of the first steering cylinder  21  moves along the longitudinal axis  23  of the first steering cylinder  21 , axially moving the first steering rod  31  to rotate the first steering knuckle  11 . 
     Further, the first steering cylinder  21  and the second steering cylinder  22  may be coupled to an axle body  57  via mounting interfaces  59  (e.g., mounting plates). Further, the first steering cylinder  21  may be positioned above the second steering cylinder  22  with regard to the z-axis. 
     The first steering cylinder  21  has a second end  21 ″ that is coupled to the third steering rod  33 . The second end  21 ″ of the first steering cylinder  21  is axially movable along a longitudinal axis  23  of the first steering cylinder  21  with respect to the main body  21 ′″ of the first steering cylinder  21 . When the first steering cylinder  21  is actuated, the second end  21 ″ of the first steering cylinder  21  moves along the longitudinal axis  23  of the first steering cylinder  21 , axially moving the third steering rod  31  to rotate the second steering knuckle  12 . When the first steering cylinder  21  is actuated, for instance the first end  21 ′ and the second end  21 ″ of the first steering cylinder move along the longitudinal axis  23  of the first steering cylinder  21  in the same direction and by the same distance. 
     The second steering cylinder  22  has a first end  22 ′ that is coupled to the second steering rod  32 . The first end  22 ′ of the second steering cylinder  22  is axially movable along a longitudinal axis  25  of the second steering cylinder  22  with respect to a main body  22 ′″ of the second steering cylinder. When the second steering cylinder  22  is actuated, the first end  22 ′ of the second steering cylinder  22  moves along the longitudinal axis  25  of the second steering cylinder  22 , axially moving the second steering rod  32  to rotate the first steering knuckle  11 . 
     The redundant steering system  1  may comprise a first lever portion  41  and a second lever portion  42 . The first lever portion  41  has a first end portion  41 ′ and a second end portion  41 ″. The first end portion  41 ′ of the first lever portion  41  is rotatably coupled to the first steering rod  31  at a first coupling position x 1 . The second lever portion  42  has a first end portion  42 ′ and a second end portion  42 ″. The first end portion  42 ′ of the second lever portion  42  is rotatably coupled to the second steering rod  32  at a second coupling position x 2 . 
     The redundant steering system  1  may further comprise a third lever portion  43 . The third lever portion  43  has a first end portion  43 ′ and a second end portion  43 ″. The first end portion  43 ′ of the third lever portion  43  is rotatably coupled to the third steering rod  33  in a third coupling position x 3 . 
     The first end portion  41 ′ of the first lever portion  41  and the first end portion  42 ′ of the second lever portion  42  are distanced from each other. The second end portion  41 ″ of the first lever portion  41  and the second end portion  42 ″ of the second lever portion  42  are, for instance directly, fixed to each other. 
     The second lever portion  42  has a second longitudinal axis  27  arranged substantially perpendicular to the first steering axis I. 
     The first steering cylinder  21  and the second steering cylinder  22  are arranged substantially parallel to each other. 
     The first coupling position x 1  and the second coupling position x 2  are disposed on a first coupling axis I C  parallel to the first steering axis I. The second steering knuckle  12  defines a second steering axis II. The first steering knuckle  11  may be rotated around the first steering axis I. The second steering knuckle  12  may be rotated around the second steering axis II. 
     The first steering cylinder  21  and the second steering cylinder  22  may be substantially identical in design. The first steering cylinder  21  and the second steering cylinder  22  are driven hydraulically via a hydraulic actuation system  30 . In another embodiment, the first or the second hydraulic cylinder  21 ,  22  may be driven mechanically via a mechanical actuation assembly  32 . 
     Further, the first steering rod  31  and the second steering rod  32  may be substantially identical in design. 
     The first steering rod  31  and the second steering rod  32  are each rotatably coupled to the first steering knuckle  11  at a distance from the first steering axis I and at a different position x 1 , x 2  along the first steering axis I. The third steering rod  33  is rotatably coupled to the second steering knuckle  12  at a distance from the second steering axis II. 
     A torque to turn the first steering knuckle  11  and the second steering knuckle  12  is composed of a force provided by the first steering cylinder  21  and a lever arm determined by the distance between the steering axis I and the pivot point x 1 . In case of inoperability of the first steering cylinder  21 , the torque may be provided by the second steering cylinder. This torque is composed by the force of the second steering cylinder  22  and a lever arm determined by the distance between the steering axis I and the pivot point x 2 . 
     The redundant steering system may comprise a valve unit  5  hydraulically connected to the first steering cylinder  21  and the second steering cylinder  22 . This steering system  70  is for example shown in  FIG. 2 . The steering system  70  is an example of the system  1 , depicted in  FIG. 1 . Therefore, similar components are labelled accordingly. A control unit  6  is connected to the valve unit  5  and configured to control the valve unit. The control unit may comprise a flow generating unit  60 , for example a hydraulic pump. A hydraulic line  61  may provide fluidic communication between the flow generating unit  60  and the valve unit  5 . Further, hydraulic lines  62  may provide fluidic communication between the valve unit  5  and the first steering cylinder  21  and the second steering cylinder  22 . 
     In order to enable steering even in the event of degradation (e.g., inoperability) of valve unit  5 , the redundant steering system may comprise a first valve unit  51  and a second valve unit  52 , each connected to the control unit  6 . The control unit  6  is configured to control the first valve unit  51  and the second valve unit  52  independently of each other. This configuration is shown in  FIG. 3 . As such  FIG. 3  depicts another steering system  80 . The steering system  80  is another example of the steering system  1 , depicted in  FIG. 1  and similar components are labelled accordingly. 
     Further, a steering wheel  7  may be provided. The control unit  6  is connected to the steering wheel  7  and the control unit  6  is configured to receive a steering angle or data indicative of a steering angle. The control unit  6  is further configured to control the first valve unit  51  and the second valve unit  52  based on the received steering angle to set a steering via the first steering cylinder, or—in case of degradation (e.g., inoperability) of the first steering cylinder  21  and/or a degradation (e.g., inoperability) of the first valve unit  51 —via the second steering cylinder. 
     Further, as shown in  FIG. 3 , the redundant steering system  80  may include a first flow generating unit  63  that is in fluidic communication with the first control valve  51  and a second flow generating unit  64  that is in fluidic communication with the second control valve  52 . The first and second flow generating units, shown in  FIG. 3  as well as the other flow generating units described herein, may be hydraulic pumps and/or hydraulic pistons. Further, hydraulic lines  65 ,  66  may provide fluidic communication between the first flow generating unit  63  and the second flow generating unit  64  and the first control valve  51  and the second control valve  52 . 
     An axis system  199  that include an x-axis, a y-axis, and a z-axis is provided in  FIGS. 1-3  for reference. The z-axis may be parallel to a gravitational axis, the y-axis may be lengthwise axis, and the x-axis may be a lateral axis, although the axes may have other orientations, in other examples. 
     As used herein, the terms “approximately” and “substantially” are construed to mean plus or minus five percent of the range, unless otherwise specified.