Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D7/00—Steering linkage; Stub axles or their mountings
  • B62D7/22—Arrangements for reducing or eliminating reaction, e.g. vibration, from parts, e.g. wheels, of the steering system
  • B62D7/224—Arrangements for reducing or eliminating reaction, e.g. vibration, from parts, e.g. wheels, of the steering system acting between the steering wheel and the steering gear, e.g. on the steering column
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
  • F16F15/10—Suppression of vibrations in rotating systems by making use of members moving with the system
  • F16F15/12—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon
  • F16F15/121—Suppression of vibrations in rotating systems by making use of members moving with the system using elastic members or friction-damping members, e.g. between a rotating shaft and a gyratory mass mounted thereon using springs as elastic members, e.g. metallic springs
  • F16F15/124—Elastomeric springs
  • F16F15/1245—Elastic elements arranged between substantially-radial walls of two parts rotatable with respect to each other, e.g. between engaging teeth
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
  • B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
  • B62D1/16—Steering columns
  • B62D1/20—Connecting steering column to steering gear

Definitions

• the present invention relates generally to work machines such as agricultural tractors, more particularly to hydraulic power steering systems for such work machines, and still more particularly to steering column damper systems to overcome vibrations from the power steering system hydraulic steering unit in such work machines.
• Work machines of many different types such as agricultural tractors and other self- propelled implements, are provided with hydraulic steering systems to facilitate machine operation. Operators commonly spend prolonged time periods operating a machine in a more or less continuous manner. For example, in farming operations, the available windows of time for preparing fields and planting crops and for harvesting the crops at optimum crop condition can be quite limited. Hydraulic steering systems lessen fatigue and enhance the comfort of an individual operating the implement. Modern work machines of these types frequently are provided with operator cabins for both safety and comfort of the operator.
• United States Patent Application Publication 2002/0190450 teaches a damper mechanism for a steering device to avoid micro vibrations generated by wheels that can be transferred to the steering wheel.
• An inner member is connected to a steering shaft, an outer member is connected to a universal joint and an elastic body is positioned between the two members.
• the elastic body has a variable thickness. For small angular rotations the thicker part of the elastic body provides the only damping structure until a gap is covered. For larger angular rotations the thick part and thin part are combined to provide resistance. While variable torsional stiffness is provided, it is provided as only two steps.
• a damper with low vibration transmissibility torsionally, axially and transversely It is desirable to have a damper of variable resistance in a steering column of a hydraulic steering system, which can be customized easily for different machines and machine uses, and which is softer or more yielding in some steering system operating conditions and stiffer or more resistant in other steering system operating conditions. More specifically, it is desirable to provide a damper in a steering column of a hydraulic steering system having variable torsional stiffness according to the applied torsional torque, to optimize the transmissibility of the system, making the resonance frequency variable, depending on the instantaneous torque transmitted.
• the present invention provides a compact damper structure providing torsional, axial and transverse damping functions within a compact structure.
• the translational damper can be shaped in different ways to obtain different torsional stiffness strategies as desired. At lower loads, damper contact surfaces are small so that the initial compression zone is small. At higher loads, the contact surface is larger and a larger compression zone is applied.
• the invention in one form is directed to a damping assembly for a power steering system to control vibrations from a hydraulic steering unit to a steering shaft in the power steering system.
• the damping assembly is provided with vibration dampers between the steering shaft and the hydraulic steering unit.
• the damping assembly includes both clockwise and counterclockwise dampers that are configured to provide changing resistance in response to rotation of the steering shaft.
• the invention in another form is directed to a damping assembly for a power steering system to control vibrations from a hydraulic steering unit to a steering shaft in the power steering system.
• the damping assembly is provided with vibration dampers between the steering shaft and the hydraulic steering unit.
• the damping assembly includes a flywheel having a bottom and a side defining a cavity, and a cover over the cavity. Clockwise and counterclockwise dampers are disposed in the cavity and are configured to provide changing resistance in response to rotation of the steering shaft.
• the invention in yet another form is directed to a damping assembly for a power steering system to control vibrations from a hydraulic steering unit to a steering shaft in the power steering system.
• the damping assembly is provided with vibration dampers between the steering shaft and the hydraulic steering unit.
• the damping assembly includes a flywheel having a bottom and a side defining a cavity.
• a rotor having a hub with arms is disposed in the cavity and has a collar extending through the cover and connected to the steering shaft.
• Clockwise and counterclockwise dampers are provided between the arms of the rotor and pediments in the flywheel.
• the invention in a further form is directed to a damping assembly for a power steering system to control vibrations from a hydraulic steering unit to a steering shaft in the power steering system.
• the damping assembly is provided with vibration dampers between the steering shaft and the hydraulic steering unit.
• the damping assembly includes a flywheel configured to have a natural frequency below vibration frequencies generated from operation of the hydraulic steering unit.
• damping assembly provides variable torsional stiffness against torsional vibrations from a hydraulic steering unit.
• Fig. 1 is a schematic, fragmentary illustration of a work machine with a hydraulic power steering system in which the damper assembly disclosed herein can be used;
• Fig. 2 is a perspective view of the power steering column of the power steering system
• Fig. 3 is an exploded view of a portion of the power steering system
• Fig. 4 is an elevational view of a portion of the power steering system
• Fig. 5 is a cross-sectional view of the portion of the power steering system shown in Fig. 4, taken along line 5-5 of Fig. 4;
• Fig. 6 is a cross-sectional view of the portion of the power steering system shown in Fig. 5, taken along line 6-6 of Fig. 5;
• Fig. 7 is a perspective view of the end of the damping assembly
• Fig. 8 is an end elevational view of the damping assembly
• Fig. 1 1 is a schematic, fragmentary illustration similar to Fig. 1 , but illustrating several dimensional relationships.
• Power steering system 200 is anchored within operator cab 104 by a column support 1 10 anchored to operator cab 104 at connections 1 12. Pivotal connections 1 14 connect column support 1 10 to an adjustable steering column housing 1 16. The in- cab portion of power steering system 200 is anchored to cab 104 by anchors 1 18.
• power steering damping assembly 212 includes a flywheel 214, an axial/transverse damper 216, a rotor 218 and a cover 220.
• Flywheel 214 is an open-ended, somewhat bowl-like housing for receiving axial/transverse damper 216 and rotor 218 therein.
• Rotor 218 nests within axial/transverse damper 216, which itself nests within flywheel 214.
• Cover 220 is attached to flywheel 214 with axial/transverse damper 216 and rotor 218 nested therein. Accordingly, torsional, axial and translational dampers are contained within the compact assembly of flywheel 214 and cover 220.
• Flywheel 214 can be used to attenuate vibration and sound conveyed into cab 104 by controlling the weight and dimensions of flywheel 214 relative to the vibration frequency of the hydraulic steering unit 204.
• the natural frequencies of components in steering column 202 can approach the range of vibration frequencies from hydraulic steering unit 204 such that noise and vibration are transmitted through resonance and amplified.
• Flywheel 214 provides a readily configurable mass for which the composition, weight and dimensions can be selected by design to have a natural frequency outside the frequency range annoying to human operators. For example, by changing the size and mass of flywheel 214, the natural frequency of flywheel 214 can be controlled to be lower than the frequency range generated by the operation of hydraulic steering unit 204, thereby attenuating resonant transmission of vibrations from hydraulic steering unit 214. More specifically, if hydraulic steering unit 214 generates frequencies in the range of 1 10- 540 Hz, designing flywheel 214 with mass and dimensions for a natural frequency of less than 100 Hz can achieve desired attenuation.
• Pediment covers 248 are spaced from one another about the periphery of axial/transverse damper 216 as defined by side 242. Pediment covers 248 cover the outer end surfaces of pediments 228, leaving the side surfaces of pediments 228 exposed in cutout indentations 244. Axial/transverse damper 216 thereby defines an annular, open ended cavity 250 above bottom 240 and between side 242 and center cylinder 246, the cavity 250 being interrupted by cutout indentations 244. Cavity 250 is configured to receive rotor 218 therein. As can be seen in Figs.
• axial/transverse damper 216 substantially covers the inner surfaces of flywheel 214 except for the exposed side surfaces of pediments 228, and provides a cushion between flywheel 214 and rotor 218. Accordingly, axial/transverse damper 216 provides cushioning or dampening against the transmission of vibrations from flywheel 214 to rotor 218, and primarily the axial and transverse vibrations.
• Rotor 218 includes an axially extending, bifurcated collar 260 that extends through cover 220 and is configured to receive steering shaft 208 therein. Rotor 218 further defines four radially extending arms 262, 264, 266, 268 from a central hub 270. As thus far described, rotor 218 can be of metal or other strong, rigid material. Arms 262, 264, 266, 268 are associated with dampers 272, 274, 276, 278, the dampers being made of rubber or other resilient material. Dampers 272, 274, 276, 278 are rotational dampers operative when steering wheel 206 is rotated either clockwise or counterclockwise.
• dampers 272, 274, 276, 278 are positioned on alternating sides of arms 262, 264, 266, 268 such that during clockwise rotation of rotor 218, two dampers 272, 276 are carried forward of the respective arms 262, 266 with which they are associated, and during counterclockwise rotation of rotor 218 the other two dampers 274, 278 are carried forward of the respective arms 264, 268 with which they are associated.
• Hub 270 and arms 262, 264, 266, 268 thereof, together with dampers 272, 274, 276, 278 associated therewith, are sized, shaped and configured to fit within cavity 250 of axial/transverse damper 216, as limited by pediments 228 exposed therein.
• damping assembly 212 With reference now more particularly to Figs. 7-10, the operation of damping assembly 212 will be described.
• References made herein to a "forward rotational direction" of any of the dampers 272, 274, 276, 278 is intended to mean the rotational direction in which the damper leads the support arm 262, 264, 266, 268 with which it is associated. Accordingly, the forward rotational direction of dampers 272, 276 is clockwise rotation of rotor 218, and the forward rotational direction of dampers 274, 278 is counterclockwise rotation of rotor 218.
• dampers 272, 274, 276, 278 are backwardly reclined relative to the confronting faces of pediments 228 in the forward rotational directions, and trailing faces of the dampers 272, 274, 276, 278 are forwardly inclined relative to the confronting faces of the arm 262, 264, 266, 268 associated therewith.
• a minimal preload compression is provided of dampers 272, 274, 276, 278 between associated arms 262, 264, 266, 268 and the pediments 228. Accordingly, as shown in Figs.
• Figs. 9 and 10 illustrate the minimal contact areas "A" and the increased contact areas "B” for one of the clockwise dampers (272) that occurs from clockwise rotation. It should be understood that a similar change has also occurred for the other clockwise damper (276) in Fig. 10; and that similar changes will occur on the counterclockwise dampers (274, 278) when rotated in the forward rotational directions thereof.
• the arms 262, 264, 266, 268 also can be shaped to affect the changes in contact areas upon rotation of rotor 218.
• Material selections for the contacting surfaces also can be selected with desired characteristics influencing the change in torsional resistance. With the damper assembly described herein, the change of torsional resistance is highly controllable. It is even possible to provide one rate of change for clockwise rotation and a different rate of change for counterclockwise rotation by selecting desirable materials and shaping the contacting surfaces to achieve the desired result.
• Fig. 1 1 it can be appreciated that the interface of operator cab 104 with column support 1 10, steering column 202 and hydraulic steering unit 204, if varied from design tolerances, can interrupt proper alignment of steering shaft 208 with hydraulic steering unit 204. More specifically, proper alignment can be affected by the relationships between a dimension "W" representing the width between the axis of steering column 202 and support connections 1 12 and a dimension "L” representing the length from the anchor surface of cab 104 to the pivotal connections 1 14. Proper alignment is important to minimize vibration transmission.
• Steering shaft 208 is segmented, with a proximal portion 210 and a distal portion 212 and connected at a cardan joint 214.
• a stub connector 290 includes a gear element 292 at the distal end thereof engaged in a receiver 294 of hydraulic steering unit 204 (Fig. 1 1 ).
• a globular element 296 at the proximal end of stub connector 290 defines transverse openings 298.
• a shaft 300 extends through transverse openings 298, and is secured by pins 302. At a center portion 304 thereof, shaft 300 is cylindrical.
• a pivot 306 is held also in the globular proximal end 296 by a pin 308.
• Damper assembly 212 provides sufficient flexing ability to compensate for misalignment caused by variations in the for aforedescribed dimensions "W” and "L".
• the rolling surface contact between shaft 300 and pivot 304 allows for compensation easily and quickly.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Aviation & Aerospace Engineering (AREA)
• Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
• Steering Controls (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=58163151

Family Applications (1)

Country Status (3)

Families Citing this family (2)

Family Cites Families (5)

• 2016
  • 2016-11-09 IT IT102016000113081A patent/IT201600113081A1/it unknown
• 2017
  • 2017-11-07 EP EP17797314.6A patent/EP3538422A1/en not_active Withdrawn
  • 2017-11-07 WO PCT/EP2017/078498 patent/WO2018087096A1/en unknown

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