Patent Application
20210131523
Vehicles typically include steering systems. During operation of a vehicle, the steering system can be subject to vibrations and shocks from the driving surface. Some steering systems include a steering damper or steering stabilizer to absorb or dampen the vibrations and shocks from the driving surface.
With reference to the Figures, a steering damper assembly 30 includes a cylindrical pressure tube 32 including a first endcap 34, a second endcap 36, and a tubular wall 40 defining and extending along an axis A from the first endcap 34 to the second endcap 36, the pressure tube 32 defining a working chamber 42; a piston assembly 44 disposed in the working chamber 42 and dividing the working chamber 42 into a first working chamber 46 adjacent the first endcap 34 and a second working chamber 48 adjacent the second endcap 36; a reserve tube 50 extending circumferentially around the pressure tube 32 and defining a reservoir chamber 52 that is radially between the reserve tube 50 and the pressure tube 32; a base valve 54 fluidly connecting and controlling flow between the second working chamber 48 and the reservoir chamber 52; and a piston rod 56 fixed to the piston assembly 44 and extending through the first endcap 34 of the pressure tube 32. The reserve tube 50 includes a cylindrical portion 58 and a bulged portion 60. The cylindrical portion 58 extends from the first endcap 34 of the pressure tube 32 toward the second endcap 36 of the pressure tube 32 and extends concentrically around the pressure tube 32, the cylindrical portion 58 having an inner radius Rcyl from the axis A. The bulged portion 60 includes a first circumferential section 62 and a second circumferential section 64, the first circumferential section 62 having a maximum radial distance Lbul1 from the axis A at most equal to the inner radius Rcyl of the cylindrical portion 58, and the second circumferential section 64 having a maximum radial distance Lbul2 from the axis A greater than the inner radius Rcyl of the cylindrical portion 58.
The steering damper assembly 30 provides a way to mitigate negative effects of air introduced into the reservoir chamber 52. The bulged portion 60 of the reserve tube 50 provides a location for air in the reservoir chamber 52 to go, which can prevent the air from traveling into the working chamber 42. Air in the working chamber 42 can cause lagging in the absorption or dampening of shocks and vibrations. Moreover, the shape of the reserve tube 50 with the cylindrical portion 58 and the bulged portion 60 provides an easy-to-manufacture design using a small number of parts and a small amount of material. Finally, the steering damper assembly 30 has a compact shape, which helps packaging in a steering system of a vehicle.
With reference to
With reference to
The pressure tube 32 defines the working chamber 42. The working chamber 42 is contained within the pressure tube 32. The working chamber 42 is sealed such that fluid can only flow into or out of the working chamber 42 through the base valve 54.
The piston assembly 44 is disposed in the working chamber 42. The piston assembly 44 has a circular cross-section centered on the axis A and forming a seal with the tubular wall 40. The piston assembly 44 contacts and forms a seal with the tubular wall 40 circumferentially for 360° around the axis A. The piston assembly 44 divides the working chamber 42 into the first working chamber 46 and the second working chamber 48. The first working chamber 46 is adjacent the first endcap 34 and is enclosed by the first endcap 34, the tubular wall 40, and the piston assembly 44. The second working chamber 48 is adjacent the second endcap 36 and is enclosed by the second endcap 36, the tubular wall 40, and the piston assembly 44.
The piston assembly 44 includes a piston valve 70. The piston valve 70 permits flow between the first working chamber 46 and the second working chamber 48, i.e., through the piston assembly 44, as the piston assembly 44 moves axially, i.e., translates along the axis A. As the piston assembly 44 and piston rod 56 move axially toward the second endcap 36, the piston valve 70 permits flow of fluid out of the second working chamber 48 into the first working chamber 46 to compensate for the relative change in volume between the first working chamber 46 and the second working chamber 48, and as the piston assembly 44 and piston rod 56 move axially toward the first endcap 34, the base valve 54 permits flow of fluid into the second working chamber 48 from the first working chamber 46 to compensate for the relative change in volume between the first working chamber 46 and the second working chamber 48. The piston valve 70 can be sized to permit a defined rate of flow between the first working chamber 46 and the second working chamber 48.
The piston rod 56 is fixed to the piston assembly 44. The piston rod 56 extends from the piston assembly 44 to and through the first endcap 34 of the pressure tube 32. The piston rod 56 is disposed partially inside the first working chamber 46 and partially outside the pressure tube 32. The piston rod 56 has a constant cross-section that is projected from the piston assembly 44 through the first endcap 34 to the first mount 66. The piston assembly 44, the piston rod 56, and the first mount 66 are attached to and fixed relative to each other.
The first endcap 34 includes a first-endcap seal 72 extending circumferentially around the piston rod 56 and forming a seal with the piston rod 56. The first-endcap seal 72 prevents fluid in the first working chamber 46 from leaking out of the pressure tube 32 along the piston rod 56.
The base valve 54 fluidly connects and controls flow between the second working chamber 48 and the reservoir chamber 52. The base valve 54 extends through the second endcap 36. As the piston assembly 44 and piston rod 56 move axially toward the second endcap 36, the base valve 54 permits flow of fluid out of the second working chamber 48 into the reservoir chamber 52 to compensate for the additional volume in the working chamber 42 occupied by the piston rod 56, and as the piston assembly 44 and piston rod 56 move axially toward the first endcap 34, the base valve 54 permits flow of fluid into the second working chamber 48 from the reservoir chamber 52 to compensate for the reduction in volume in the working chamber 42 occupied by the piston rod 56. The base valve 54 can be sized to permit a defined rate of flow between the second working chamber 48 and the reservoir chamber 52.
The first mount 66 provides a location to attach the steering damper assembly 30 to a steering system. The first mount 66 can permit rotation in one or more dimensions of the steering damper assembly 30 relative to the component of the steering system to which the first mount 66 is attached. For example, the first mount 66 can be a pin joint, ball joint, etc.
The first mount 66, the piston rod 56, the piston assembly 44, and a dust shield 74 (described below) together form a rigid body, i.e., are connected to each other and fixed relative to each other. The first mount 66, the piston rod 56, the piston assembly 44, and the dust shield 74 are axially movable together relative to the pressure tube 32 between a retracted position with the piston assembly 44 at a closest position to the second endcap 36, as shown in
The reserve tube 50 extends circumferentially around the pressure tube 32 and extends axially from the first endcap 34 past the second endcap 36 to the second mount 68. The reserve tube 50 includes the cylindrical portion 58, the bulged portion 60, and a conical portion 78. The reserve tube 50 is an integral piece, i.e., made of a single, uniform piece of material with no seams, joints, fasteners, or adhesives holding it together.
The reserve tube 50 defines the reservoir chamber 52. The reservoir chamber 52 is radially between the reserve tube 50 and the pressure tube 32, i.e., radially inside the reserve tube 50 and radially outside the pressure tube 32. The reservoir chamber 52 extends from the first endcap 34 to the conical portion 78. The first endcap 34 extends radially outward from the pressure tube 32 to the reserve tube 50. The reservoir chamber 52 extends between the second endcap 36 and the second mount 68. The reservoir chamber 52 is sealed except for the base valve 54. The reservoir chamber 52 and the working chamber 42 are together completely sealed from an environment outside the reserve tube 50, i.e., there are no fluid paths between the working chamber 42 or reservoir chamber 52 and the environment outside the reserve tube 50.
The cylindrical portion 58 extends axially from the first endcap 34 toward the second endcap 36 and extends to the bulged portion 60. The cylindrical portion 58 extends concentrically around the pressure tube 32. The cylindrical portion 58 has a cylindrical shape defining the axis A. The cylindrical portion 58 has a circular cross-section orthogonal to the axis A, and the circular cross-section is projected from the first endcap 34 to the bulged portion 60 along the axis A. The cylindrical portion 58 has an inner radius Rcyl measured from the axis A to an inner surface of the cylindrical portion 58, i.e., to a surface facing inward to the reservoir chamber 52.
The steering damper assembly 30 includes a foam member 76 disposed in the reservoir chamber 52. The foam member 76 extends circumferentially around the pressure tube 32, extends radially outward from the pressure tube 32 to the reserve tube 50, specifically to the cylindrical portion 58 of the reserve tube 50, and extends axially from the first endcap 34 toward the second endcap 36. The foam member 76 is axially spaced from the bulged portion 60. The foam member 76 can be a rubber, e.g., neoprene.
The bulged portion 60 extends axially from the cylindrical portion 58 to the conical portion 78 of the reserve tube 50. The bulged portion 60 extends circumferentially relative to the axis A completely around the second endcap 36, and the bulged portion 60 is spaced from the second endcap 36. The bulged portion 60 includes the first circumferential section 62 and the second circumferential section 64. The circumferential sections extend axially from the cylindrical portion 58 to the conical portion 78. The first circumferential section 62 extends circumferentially partially around the axis A from the second circumferential section 64 to the second circumferential section 64, and the second circumferential section 64 extends circumferentially partially around the axis A from the first circumferential section 62 to the first circumferential section 62. When the steering damper assembly 30 is mounted to the steering system, the first circumferential section 62 faces downward, and the second circumferential section 64 faces upward; in other words, the first circumferential section 62 is disposed below the pressure tube 32, and the second circumferential section 64 is disposed above the pressure tube 32.
With reference to
Returning to
The dust shield 74 is fixed relative to the piston rod 56 and extends from the piston rod 56. The dust shield 74 includes a conical portion 88 and a cylindrical portion 90. The conical portion 88 extends radially outward from the piston rod 56 at the first mount 66, and the conical portion 88 extends axially from the first mount 66 toward the second mount 68. The cylindrical portion 90 extends from the conical portion 88 away from the first mount 66 toward the second mount 68. The cylindrical portion 90 of the dust shield 74 extends circumferentially around the cylindrical portion 58 of the reserve tube 50. The cylindrical portion 90 of the dust shield 74 has a cylindrical shape positioned concentrically around the cylindrical portion 58 of the reserve tube 50, i.e., centered around the axis A. The end of the cylindrical portion 90 of the dust shield 74 axially closest to the second mount 68 is not directly attached to any other components of the steering damper assembly 30. An inner radius Rdust of the cylindrical portion 90 of the dust shield 74 can be smaller than the maximum radial distance Lbul2 from the axis A to the second circumferential section 64 of the bulged portion 60 of the reserve tube 50, as shown in
The dust shield 74 is axially movable relative to the pressure tube 32 between the retracted position and the extended position, along with the first mount 66, the piston rod 56, and the piston assembly 44. The dust shield 74 in the extended position, as shown in
With reference to
The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. The adjectives “first” and “second” are used throughout this document as identifiers and are not intended to signify importance, order, or quantity. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.
