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WO1994006667A1 - Direction assistee a cremaillere, notamment pour automobiles - Google Patents

Direction assistee a cremaillere, notamment pour automobiles Download PDF

Info

Publication number
WO1994006667A1
WO1994006667A1 PCT/EP1993/002463 EP9302463W WO9406667A1 WO 1994006667 A1 WO1994006667 A1 WO 1994006667A1 EP 9302463 W EP9302463 W EP 9302463W WO 9406667 A1 WO9406667 A1 WO 9406667A1
Authority
WO
WIPO (PCT)
Prior art keywords
pinion
rack
steering
servo
piston valve
Prior art date
Application number
PCT/EP1993/002463
Other languages
German (de)
English (en)
Inventor
Wilfried Leutner
Helmut KNÖDLER
Original Assignee
Zf Friedrichshafen Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zf Friedrichshafen Aktiengesellschaft filed Critical Zf Friedrichshafen Aktiengesellschaft
Publication of WO1994006667A1 publication Critical patent/WO1994006667A1/fr

Links

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
    • B62D5/20—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application
    • B62D5/22—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle specially adapted for particular type of steering gear or particular application for rack-and-pinion type
    • 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
    • B62D5/065—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 specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
    • 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
    • B62D5/087—Sliding spool valves

Definitions

  • the invention relates to a power assisted rack and pinion steering system, in particular for motor vehicles, according to the preamble of claim 1.
  • a pinion is rotatably mounted in a steering housing.
  • a rack is guided axially displaceably in the steering housing and is spring-loaded
  • a servo motor is used for auxiliary power support and is connected to the toothed rack.
  • a control device for controlling a pressure medium to and from the servo motor is adjustable depending on a movement of the pinion.
  • Such a power assisted rack and pinion steering is known from EP-Bl-01 92 641.
  • the helical toothing of the pinion creates a force component on the pinion in the axial direction, so that the pinion is adjustable in the axial direction.
  • the control valves can be adjusted by this axial displacement of the pinion.
  • the well-known power steering works on the principle of the closed center. This keeps the energy requirement low.
  • the helix angle of the pinion should be over 35 degrees if possible. This severely limits the choice of pinion teeth.
  • the actuation of the control valves can be impaired in that the transverse forces acting on the rack are supported on the pinion and can thus increase the friction for the axial displacement of the pinion.
  • the known power assisted rack and pinion steering system cannot be used if only a limited installation space is available in the diameter range of the pinion housing
  • the invention has for its object to avoid the shortcomings described without additional design effort.
  • the use of pinions with different helix angles should be possible, even with helix angles that are less than 35 degrees.
  • the energy requirement during operation of the steering should not change significantly.
  • the solution is achieved in particular in that the pinion is pivotally mounted in a fixed bearing and in a floating bearing.
  • the control device is designed in the form of a piston valve which is arranged in the region of the floating bearing and whose axis is essentially perpendicular to the axis of the pinion. This means that it is not the axial forces acting on the pinion that are used to actuate the control valve, but rather the transverse forces. If the steering spindle is turned, the toothing of the pinion initially rolls in the toothing of the still fixed rack and thus moves the pin of the pinion, which is guided in the floating bearing, so that the piston valve is adjusted.
  • the servo pump is driven by an electric motor
  • a device for detecting the movements of the pinion or the steering torque can be used, which works analogously.
  • an inductively operating sensor can be connected to the piston of the piston valve. With the help of the signals from this sensor, the speed of the servo pump and thus its delivery rate and delivery pressure can be changed by changing the voltage and / or the electric current.
  • the servo pump driven by the electric motor is switched on by a switch when a certain steering torque is exceeded and switched off when a certain steering torque is undershot. If, on the other hand, the servo pump is driven by the vehicle engine, the pump can be switched on and off via an interposed clutch.
  • FIG. 1 shows a longitudinal section through the rack and pinion hydraulic steering system according to the invention.
  • FIG. 2 shows a partial cross section through the power assisted-rack steering system of FIG. 1 in the region of the pinion;
  • a pinion 2 is rotatably mounted in two bearings 3 and 4.
  • the pinion 2 carries at one end a steering spindle connection 5 for connection to a steering member, for example a steering spindle (not shown) with a steering handwheel.
  • a steering member for example a steering spindle (not shown) with a steering handwheel.
  • One of the bearings preferably the bearing 3, which is located in the vicinity of the steering spindle connection 5, is designed as a fixed bearing.
  • the other bearing, preferably the bearing 4 facing away from the steering spindle connection 5, is designed as a floating bearing.
  • the pinion 2 is in engagement with a toothed rack 6 via its toothing, which is guided axially displaceably in the steering housing 1.
  • the toothed rack 6 is pressed against the toothing of the pinion 2 in a known manner with the aid of a spring-loaded pressure piece 7.
  • the pinion 2 is supported on one side in the fixed bearing 3 and on the other side via the floating bearing 4 in the steering housing 1.
  • Pressure plate 10 serves to enable a low-friction and low-wear movement of the floating bearing 4.
  • the outer ring 8 of the floating bearing 4 can roll on the pressure plate 10.
  • the pressure plate 10 can optionally be dispensed with.
  • a servo motor 11 is used for auxiliary power support, the piston rod 12 of which is firmly connected to the rack 6.
  • the servo motor 11 contains two cylinder spaces 13 and 14, which are connected via working lines 15 and 16 to two cylinder connections 17 and 18 of a control device 20.
  • the control device 20 also has an inlet connection 21 to which a pressure medium source is connected.
  • a container 25 is connected to two return connections 23 and 24.
  • the control device 20 contains a piston valve 26, the axis of which is essentially perpendicular to the axis of the pinion 2.
  • the piston valve 26 is arranged in the area of the floating bearing 4.
  • the piston valve 26 contains a piston 27, which is arranged displaceably in a bore 28 of the steering housing 1 and is centered in its central position by two springs 30 and 31.
  • the piston 27 is carried along via a pin-like extension 32 of the pinion 2, which has a spherical or spherical end and engages in a recess 33 of the piston 27.
  • the recess 33 is designed as a bore in the piston 27.
  • the piston valve 26 has on its piston 27 control grooves 34 with control edges, which cooperate in a known manner with control grooves 35 of the bore 28 and are connected in a known manner to the cylinder connections 17 and 18, the inlet connection 21 and the return connection 23 and 24.
  • the control grooves 34 and 35 are all on one side of the recess 33.
  • the piston 27 is sealed in the bore 28 by two seals 36 and 37 in such a way that the pressure medium controlled via the piston valve 26 to and from the servo motor 11 remains restricted to the area of the control grooves 34 and 35.
  • a servo pump 38 is connected to the inlet connection 21 and is driven by an electric motor 40 according to FIG. 4. In another embodiment, which is shown schematically in FIG. 5, the servo pump 38 is driven by a vehicle engine 41 via a switchable clutch 42.
  • a device 43 for detecting the movements of the pinion 2, in particular the pivoting movements, and thus for detecting the steering torque is arranged on the piston valve 26.
  • the device 43 measures the torque via the path of the piston 27. It is an inductive measuring device with measuring coils 44 and a core 45, which is firmly connected to the piston 27.
  • the device for detecting the movements of the pinion 2 and the steering torque is designed as a switch 46.
  • a lever 47 which engages with a crank in a groove 48 of the piston 27, is used to actuate the switch 46. If the piston 27 is displaced, the lever 47 runs up the groove slope and thus actuates the switch 46.
  • control grooves 34 and 35 are constructed symmetrically to one another, a corresponding functional sequence results when the steering hand wheel is in the opposite direction of rotation.
  • the servo pump 38 is controlled via the device 43 for detecting the movements of the pinion 2 and the steering torque, depending on the size of the steering torque.
  • the servo pump 38 can be switched on, for example, when a specific steering torque is exceeded and switched off when a specific steering torque is undershot. Depending on the embodiment, this can be done, for example, by switching the electric motor 4 on or off or by opening or closing the clutch 42.
  • the device 43 is designed for detection as a measuring coil 44, as shown in FIG. 1, analog signals result for the control of the electric motor 40.
  • the electric motor 40 can then be operated with different voltages depending on the steering torque. Different steering forces can be generated by the associated variable delivery rate of the servo pump 38. If, for example, the vehicle speed is additionally detected via an electronic unit (not shown), the auxiliary power assistance can be varied at the same time as a function of the vehicle speed. Another possibility of changing the speed of the electric motor 40 and thus the delivery rate of the servo pump 38 is to regulate the electric current of the electric motor 40. Reference sign

Landscapes

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

Abstract

Dans une direction assistée à crémaillère, prévue notamment pour des automobiles, un pignon (2) logé dans un carter de direction (1) est en prise avec une crémaillère (6). Afin de permettre la servo-assistance, un servomoteur (11) est relié cinétiquement à la crémaillère (6). Le pignon (2) est logé pivotant dans un palier fixe (3) et dans un palier libre (4). Une soupape à piston (26) montée dans la zone du palier libre (4) a un axe sensiblement perpendiculaire à l'axe du pignon (2). Le palier libre (4) est guidé coulissant perpendiculairement à son axe, uniquement en direction de l'axe de la soupape à piston (26) dans le carter de direction (1). Dans cette direction assistée à crémaillère, pour actionner les soupapes de commande, on n'utilise pas les forces axiales qui agissent sur le pignon (2), mais les forces transversales. L'actionnement des soupapes ne dépend par conséquent pas de l'angle d'hélice des dents du pignon. Cette direction assistée à crémaillère comprend en outre une bobine de mesure (44) fonctionnant de manière inductive, dont le noyau (45) est relié au piston (27) de la soupape à piston (26). La bobine de mesure (44) permet de déterminer les mouvements pivotants du pignon (2) et par conséquent le moment de direction et de les traiter ultérieurement pour modifier la vitesse de rotation de la servopompe (38) en fonction du moment de direction. La servopompe (38) ne fonctionne que lorsqu'une servo-assistance est effectivement requise.
PCT/EP1993/002463 1992-09-16 1993-09-13 Direction assistee a cremaillere, notamment pour automobiles WO1994006667A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4230957.3 1992-09-16
DE19924230957 DE4230957A1 (de) 1992-09-16 1992-09-16 Zahnstangen-Hilfskraftlenkung, insbesondere für Kraftfahrzeuge

Publications (1)

Publication Number Publication Date
WO1994006667A1 true WO1994006667A1 (fr) 1994-03-31

Family

ID=6468080

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1993/002463 WO1994006667A1 (fr) 1992-09-16 1993-09-13 Direction assistee a cremaillere, notamment pour automobiles

Country Status (2)

Country Link
DE (1) DE4230957A1 (fr)
WO (1) WO1994006667A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2290510A (en) * 1994-06-27 1996-01-03 Daimler Benz Ag Hydraulic power steering system with electrically driven pump
US5802949A (en) * 1996-08-12 1998-09-08 General Motors Corporation Closed center power steering gear

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10345293A1 (de) 2003-09-30 2005-05-04 Bayerische Motoren Werke Ag Betriebsverfahren für ein hilfskraftverstärktes Hydro-Lenksystem eines Kraftfahrzeugs

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0249315A2 (fr) * 1986-06-09 1987-12-16 Trw Cam Gears Limited Mécanisme de direction assistée de véhicule
EP0192641B1 (fr) * 1983-11-05 1988-01-07 ZF FRIEDRICHSHAFEN Aktiengesellschaft Direction assistee a cremaillere, en particulier pour vehicules a moteur
DE3909210A1 (de) * 1989-03-21 1990-09-27 Teves Gmbh Alfred Elektrohydraulische lenkhilfe fuer kraftfahrzeuge
DE4040003A1 (de) * 1990-06-22 1992-01-02 Bosch Gmbh Robert Servolenkung fuer fahrzeuge

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0192641B1 (fr) * 1983-11-05 1988-01-07 ZF FRIEDRICHSHAFEN Aktiengesellschaft Direction assistee a cremaillere, en particulier pour vehicules a moteur
EP0249315A2 (fr) * 1986-06-09 1987-12-16 Trw Cam Gears Limited Mécanisme de direction assistée de véhicule
DE3909210A1 (de) * 1989-03-21 1990-09-27 Teves Gmbh Alfred Elektrohydraulische lenkhilfe fuer kraftfahrzeuge
DE4040003A1 (de) * 1990-06-22 1992-01-02 Bosch Gmbh Robert Servolenkung fuer fahrzeuge

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2290510A (en) * 1994-06-27 1996-01-03 Daimler Benz Ag Hydraulic power steering system with electrically driven pump
GB2290510B (en) * 1994-06-27 1998-08-05 Daimler Benz Ag Hydraulic power steering system
US5802949A (en) * 1996-08-12 1998-09-08 General Motors Corporation Closed center power steering gear

Also Published As

Publication number Publication date
DE4230957A1 (de) 1994-03-17

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