Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D5/00—Power-assisted or power-driven steering
  • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
  • B62D5/08—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by type of steering valve used
  • B62D5/083—Rotary valves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits

Definitions

• the invention relates to a reaction arrangement on a hydraulic servo valve arrangement designed in the manner of a rotary slide valve arrangement, which has a rotary slide valve and a control bushing coaxially encompassing it and rotatable relative to the rotary slide valve and is intended in particular for power steering systems of motor vehicles.
• Hydraulic power steering is standard in most vehicles. It is fundamentally known to change the manual force noticeable on the steering handwheel or to be exerted during steering maneuvers, for example to make the steering somewhat stiff at high speed and particularly smooth at low speed, especially in a speed range typical for maneuvering. For this purpose, so-called reaction arrangements are used, by means of which the manual force necessary for an adjustment of the servo valve arrangement can be changed. In the case of a servo valve arrangement designed in the manner of a rotary slide valve arrangement, this means that the force required for rotating the rotary slide valve and control bushing relative to one another can be varied in a controllable manner.
• the invention is based on the general idea of arranging the axial V-grooves interacting with the reaction bodies with the greatest possible radial distance from the rotary slide axis in order to be able to generate comparatively large reaction forces at limited hydraulic pressures.
• flanks of the V-grooves can optionally be concave or convex, so that the respective reaction force also depends on the angle of rotation between the spool and the control bus.
• FIG. 2 is a sectional view corresponding to the section line II-II in Fig. 1,
• FIG. 3 is a sectional view corresponding to FIG. 2 of a modified embodiment
• Fig. 4 is a sectional view corresponding to FIG. 2 of a further modified embodiment
• Fig. 5 is a diagram showing the pressure difference acting on the servo motor as a function of the hand torque to be applied to the steering handwheel.
• a rotary valve 1 is comprised of a coaxial control bush 2 which is rotatably arranged within a housing 3, which is only indicated schematically.
• the rotary valve 1 and the control bushing 2 can be rotated relative to one another to a limited extent, as a result of which axial control edges 4 that interact with one another and are arranged on the rotary valve 1 or on the control bushing 2 are adjusted relative to one another in the circumferential direction of the rotary valve 1 and the control bushing 2.
• a servo motor 6 for example, a double-acting piston-cylinder unit, and hydraulically between a connection for the pressure side of a hydraulic pump 7 and a connection for a connected to the suction side of the pump 7 connected hydraulic reservoir 8, built up a controllable pressure difference in one direction or the other, so that the servo motor 6 generates a corresponding servo force in one direction or the other.
• the rotary valve or the control bushing 2 is mechanically connected to a steering handwheel, not shown, and the control bushing 2 or the rotary valve 1 is mechanically connected to the steerable vehicle wheels.
• the rotary valve 1 and the control bush 2 are coupled to each other in a manner shown below so that they can perform a limited relative rotation relative to each other, the extent of which depends on the torque transmitted between the steering wheel and the steerable vehicle wheels.
• the servo motor 6 thus generates a servo force which is dependent on the aforementioned torque and by means of which the hand force to be exerted on the steering handwheel is reduced. This is generally known.
• a bushing section 9 axially spaced from the control edges 4, which can have an enlarged inner diameter compared to the control bushing and is provided on its inner circumference with uniformly distributed V-grooves 10, each of which has a maximum depth in its axially central section reach, ie the V-grooves 10 are open radially inwards.
• a shaft part 11 Connected to the rotary valve 1 is a shaft part 11 which is concentric with the bushing section 9 and which has a number of radial bores 12 corresponding to the number of V-grooves 10.
• the shaft part 11 is rotatably connected to the rotary valve 1 so that the central axes of the radial bores 12 are each contained in an axial plane of the rotary valve 1 containing the longitudinal center line of a V-groove 10 when the rotary valve 1 and the control bushing 2 assume their central position relative to one another in the the motor connections 5 have the same hydraulic pressures.
• the bushing section 9 and the control bushing 2 can be connected to one another in a corresponding relative position in that the bushing section 9 is pressed with an inner cone 13 arranged thereon on an outer cone 14 present on the control bushing 2.
• This connection enables an exact adjustment of the socket section 9 relative to the control socket 2.
• Balls 15 are slidably received in the radial bores 12, which can be pressed into the V-grooves 10 by hydraulic pressurization with more or less great force in the manner shown below.
• An axial bore 16 is formed within the shaft part 11 and communicates with the radial bores 12.
• the axial bore 16 can be acted upon by a parameter-dependent controllable hydraulic pressure.
• the V-grooves 10 communicate via an annular space 18 formed in the housing 3 in a schematically illustrated manner with the relatively pressure-free hydraulic reservoir 8, so that the balls 15 can be urged into the V-grooves 10 by the aforementioned hydraulic pressure.
• the shaft part 11 also rotates relative to the V-grooves 10 in the bushing section 9, with the result that the balls 15 either only on the right or left flanks of the V Grooves 10 abut and generate a torque corresponding to the pressure forces which push the balls 15 radially outwards, which counteracts a rotary adjustment of the rotary valve 1 and the control bush 2 from their relative central position.
• Fig. 5 shows for different hydraulic pressures in the axial bore 16 the amount of the pressure difference ⁇ p effective between the motor connections 5 as a function of the torque M transmitted between the rotary valve 1 and the control bushing 2.
• the curve K. shows the conditions in a schematic form low hydraulic pressure in the axial bore 16, it being assumed that rotary About 1 and control socket 2 are coupled together in a torsionally flexible manner via a spring, not shown. If an increasing torque is effective in one direction or the other between rotary valve 1 and control bushing 2, rotary valve 1 and control bushing 2 are increasingly rotated relative to one another, with the result that a progressively increasing pressure difference ⁇ p occurs between the motor connections 5.
• the curve K 2 now shows the conditions at a greater hydraulic pressure in the axial bore 16. Since the balls 15 are now forced into the V-grooves 10 with increased force, an increased torque M must be effective as a result between the control slide 1 and the control bush 2 to cause a significant relative rotation between the spool and control bush 2.
• the balls 15 roll on the flanks of the V-grooves 10 during relative rotation between the control slide 1 and the control bush 2.
• the flanks have only a limited steepness in the circumferential direction of the bushing section 9.
• the diameter of the radial bores 12 should be slightly larger than the diameter of the balls 15, so that the balls 15 "float" in the radial bores 12, ie are kept away from the walls of the radial bores 12 by flowing hydraulic medium.
• the diameter difference should be small, so that the cross section of the between the inner circumference of the Radial bores and the balls 15 formed annular gap has a small dimension and the flow of the hydraulic medium is opposed to a high throttle resistance.
• V-grooves 10 each have flat flanks.
• flanks of the V-grooves 10 it is also possible to form the flanks of the V-grooves 10 according to FIGS. 3 and 4 convex or concave to achieve that the restoring forces caused by the interaction of the balls 15 with the V-grooves 10 also from the angle of Relative rotation between rotary valve 1 and control socket 2 are dependent.
• the reaction force increases (with constant hydraulic forces acting on the balls 15) with increasing angle of rotation, while in the case of convex flanks the restoring force decreases with increasing angle of rotation.
• the rotary valve 1 and the shaft part 11 can form a one-piece component according to FIG. 1. Instead, it is also possible to provide a two-part construction, the rotary slide valve 1 and shaft part 11 being able to be connected to one another, for example, by flanging or welding or by means of screws.
• control bushing 2 and the bushing section 9 can also be connected to one another by flanging or welding or screwing, in contrast to the illustration in FIG. 1. be that.
• a one-piece, one-piece construction is also possible in principle.
• the radial bores 12 can each be arranged several times next to one another in the axial direction of the shaft part 11, so that in each case a plurality of balls 15 interact with a V-groove 10.
• the V-grooves 10 can have a U-like rounded profile in their deep central region.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Power Steering Mechanism (AREA)
• Steering Control In Accordance With Driving Conditions (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7830375

Family Applications (1)

Country Status (5)

Families Citing this family (5)

Family Cites Families (9)

• 1997
  • 1997-05-24 DE DE19721755A patent/DE19721755C2/de not_active Expired - Fee Related
• 1998
  • 1998-05-15 EP EP98930693A patent/EP0983182A1/de not_active Withdrawn
  • 1998-05-15 WO PCT/EP1998/002881 patent/WO1998052812A1/de not_active Application Discontinuation
  • 1998-05-15 KR KR1019997010891A patent/KR20010012923A/ko not_active Application Discontinuation
  • 1998-05-15 JP JP10549926A patent/JP2000512242A/ja active Pending

Non-Patent Citations (1)

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