WO1997036776A1 - Hilfskraftlenkung, insbesondere für kraftfahrzeuge - Google Patents
Hilfskraftlenkung, insbesondere für kraftfahrzeuge Download PDFInfo
- Publication number
- WO1997036776A1 WO1997036776A1 PCT/EP1997/001431 EP9701431W WO9736776A1 WO 1997036776 A1 WO1997036776 A1 WO 1997036776A1 EP 9701431 W EP9701431 W EP 9701431W WO 9736776 A1 WO9736776 A1 WO 9736776A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- steering
- valve
- rocker
- valve body
- input member
- Prior art date
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
- B62D5/08—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
Definitions
- a steering valve in a valve body has two valve pistons for controlling a pressure medium from a pressure medium source to two working spaces of a servo motor and from this to a container.
- the valve pistons can be adjusted by means of a rotary movement of a steering spindle via a rocker, the rocker being connected to the steering spindle.
- a reaction chamber is adjacent to each valve piston.
- the valve pistons can be loaded into their central position by a centering device.
- the steering valve is arranged between the steering spindle and an input member of the steering.
- Such an auxiliary power steering system is known from DE 31 22 368 C2.
- This power steering works with a servo motor, the piston surfaces of which have an area ratio of close to 1: 2.
- only two pairs of control edges are provided for the actual control of the pressure medium.
- the centering and valve return is carried out via centering springs and the hydraulic reaction.
- the reaction spaces are controlled via a pair of auxiliary control edges.
- the object of the invention is to avoid the disadvantages of the known power steering system.
- the auxiliary power steering should also be possible with servomotors, the piston surfaces of which do not have an area ratio of close to 1: 2.
- the center behavior in the area of high hydraulic reaction is to be improved.
- the power steering system characterized in claim 1.
- the centering device is formed by a torsion bar which is arranged between the steering spindle and the input member of the steering and which holds the steering spindle and the input member of the steering axially together.
- the valve body is non-rotatably connected to the input member of the steering.
- the rocker is completely supported in this valve body.
- the rocker is mounted on the one hand in the valve body and on the other hand on the torsion bar firmly connected to the valve body.
- the bearing point arranged on the torsion bar also lies within the valve body.
- the valve pistons are operatively connected to the actuating surfaces of the rocker by springs. These springs can be designed to be relatively weak because they are not required for centering the steering valve.
- the reaction depends on any parameter, in particular the vehicle speed If the speed is to be regulated, the reaction areas are connected to the return flow to the container via a fixed throttle point and via a common control element with a throttle cross-section that can be changed as a function of the parameter.
- a cut-off valve is arranged between the two throttle points on the one hand and the control element on the other hand, by means of which the pressure difference in the reaction spaces can be limited to a maximum value.
- the steering valve can be adjusted very precisely in that the steering spindle is displaced relative to the torsion bar not only with respect to its rotational position, but also with respect to its longitudinal axis until the continuous pressure has reached its minimum value. Due to the longitudinal displacement of the steering spindle with respect to the torsion bar and thus with respect to the valve body, the valve pistons are adjusted in their axial direction with respect to the valve body.
- FIG. 1 shows a longitudinal section through an auxiliary power steering system according to the invention
- Fig. 2 shows a cross section through the power steering of Fig. 1 along the line II-II, on an enlarged scale.
- the invention is described with reference to a power assisted rack and pinion steering. However, the invention is also applicable to other power steering systems, for example ball nut power steering systems.
- the power steering essentially consists of a steering gear 1 with a servo motor 2, which is supplied via a steering valve 3 by a servo pump 4 with pressure medium from a container 5.
- the steering gear 1 contains in a steering housing 6 em a 7 which can be driven by a steering handwheel (not shown), which is engaged via its toothing m with a rack 8 which is guided axially displaceably in the steering housing 1.
- the pinion 7 represents the input member of the steering and is rotatably supported in the steering housing 6 by two bearings 10 and 11.
- a steering spindle 12 carries a steering shaft connection 13. When the invention is applied to a ball nut power steering system, the input element is a threaded shaft.
- a valve body 14 is non-rotatably connected to the pinion 7.
- the pinion 7 is expediently formed in one piece with the valve body 14.
- two valve pistons 15 and 16 are slidably guided.
- the valve pistons 15 and 16 are guided and mounted either directly in the valve body 14 or - as in the exemplary embodiment in FIG. 2 - in two control sockets 17 and 18 respectively.
- On the control sockets 17 and 18 and on the valve pistons 15 and 16 is arranged per em inlet control edge pair 19 or 20 and em outlet control edge pair 21 or 22. Between each inlet control edge pair 19 or 20 and the associated sequence control edge pair 21 or 22 is arranged on each valve piston 15 or 16 eme servo motor control groove 23 or 24.
- Adjacent to each valve piston 15 and 16 is a reaction chamber 25 and 26, which is controlled via a pair of reaction control edges 27 and 28, respectively.
- the two valve pistons 15 and 16 are actuated by a rocker 30, which has two actuating arms 31 and 32, each with an actuating surface 33 and 34.
- the rocker 30 is firmly connected to the steering spindle 12.
- the actuation flats 33 and 34 are arranged inclined to the longitudinal axis of the steering spindle 12, as can be seen from FIG. 1.
- the two valve pistons 15 and 16 are kept in operative connection with the two actuation surfaces 33 and 34 of the rocker 30 by springs 35 and 36 which are arranged in the reaction spaces 25 and 26.
- the steering spindle 12 is connected to the input member of the steering system formed by the pinion 7 by means of a torsion bar 37.
- the torsion bar 37 is fixedly connected to the pinion 7, for example by a pin 38, and to the steering spindle 12 by a pin 40, so that the torsion bar 37 axially holds the steering spindle 12 and the input member of the steering together.
- the rocker 30 and thus the steering spindle 12 is completely supported within the valve body 14, namely by an inner bearing 41 and an outer bearing 42.
- the inner bearing 41, together with the rocker 30, guides the steering shaft 12 to the one with the pinion 7 firmly connected torsion bar 37 mounted.
- Through the outer bearing 42 is the Rocker 30 mounted with a collar 43 directly m the valve body 14.
- a common control element 46 is used with a throttle cross-section that can be changed as a function of the parameter.
- a cut-off valve 47 is provided in a known manner, which acts as a pressure reducing valve and on the one hand from the pressure of the servo pump 4 and on the other hand from the pressure prevailing between the two fixed throttle points 44 and 45 and the control element 46 and is loaded by a spring.
- the pressure medium is supplied from the servo pump 4 to the container 5 via the open inlet control edge pairs 19 and 20 and the open outlet control edge pairs 21 and 22.
- a certain differential pressure arises between the two working spaces of the servo motor 2 em.
- this differential pressure is first eliminated by adjusting the rotational position between the steering spindle 12 and the torsion bar 37 so that it disappears.
- the steering spindle 12 is positioned opposite the torsion bar 37 additionally shifted with respect to its longitudinal axis until the continuous pressure has reached its minimum value.
- valve piston 15 on the left in FIG. 2 moves upward and the right valve piston 16 moves downward.
- the left drain control edge pair 21 and the right inflow control edge pair 20 are closed, the pressure in the left servo motor control groove 23 increases and acts on the left working space of the servo motor 2.
- the left feedback control edge pair 27 opens while the right feedback control edge pair 28 closes.
- the variable throttle of the control member 46 is open, the pressure medium can flow back to the container 5 via the left fixed throttle 44, the cut-off valve 47 and the control member 46.
- a pressure builds up in the left reaction chamber 25, while the pressure in the right reaction chamber 26 is reduced by the loss of flow at the left throttle point 44.
- the hydraulic amplification decreases and the driving stability of the vehicle is improved. This is the speed setting.
- variable throttle of the control element 46 If, on the other hand, the variable throttle of the control element 46 is closed, the flow through the left throttle 44 and its differential pressure and thus also the hydraulic torque disappears.
- the steering torque is correspondingly smaller and depends only on the angle of rotation of the steering valve 3 and the torsional stiffness of the torsion bar 37. This is the parking schedule.
- the cut-off valve 47 works in a known manner as a pressure reducing valve and limits the differential pressure at the fixed throttle points 44 and 45 to a predetermined value.
- variable throttle of the control member 46 If the variable throttle of the control member 46 is open, then with the smallest torque on the steering spindle 12, there is an imbalance of pressure in the reaction spaces 25 and 26, because, depending on the size of the control gap at the reaction control edge pairs 27 and 28, either over the left throttle point 44 or over the right throttle point 45, a larger or smaller pressure medium flow flows, which generates different differential pressures at the throttle points. However, since the corresponding sequence control edge pair 21 or 22 is not yet sufficiently closed in this process, no pressure can build up in the servo motor and the desired higher effective driving stability at higher speeds in the straight-ahead driving range results.
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
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97908279A EP0889821A1 (de) | 1996-03-30 | 1997-03-21 | Hilfskraftlenkung, insbesondere für kraftfahrzeuge |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19612872.2 | 1996-03-30 | ||
DE1996112872 DE19612872A1 (de) | 1996-03-30 | 1996-03-30 | Hilfskraftlenkung, insbesondere für Kraftfahrzeuge |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997036776A1 true WO1997036776A1 (de) | 1997-10-09 |
Family
ID=7790065
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP1997/001431 WO1997036776A1 (de) | 1996-03-30 | 1997-03-21 | Hilfskraftlenkung, insbesondere für kraftfahrzeuge |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0889821A1 (de) |
DE (1) | DE19612872A1 (de) |
WO (1) | WO1997036776A1 (de) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102013107097A1 (de) * | 2013-07-05 | 2015-01-08 | Zf Lenksysteme Gmbh | Kolbenventil |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3122368A1 (de) * | 1981-06-05 | 1982-12-23 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Hydrolenkung |
DE4230960A1 (de) * | 1992-09-16 | 1994-03-17 | Zahnradfabrik Friedrichshafen | Zahnstangen-Hilfskraftlenkung, insbesondere für Kraftfahrzeuge |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2262575C3 (de) * | 1972-12-21 | 1978-04-20 | Integral Hydraulik Langen & Co., 4000 Duesseldorf | Hydraulische Druckmittelsteueranlage zur Wegesteuerung eines doppeltwirkenden Servomotors |
DE4131449A1 (de) * | 1991-09-21 | 1993-03-25 | Zahnradfabrik Friedrichshafen | Servolenkung |
-
1996
- 1996-03-30 DE DE1996112872 patent/DE19612872A1/de not_active Withdrawn
-
1997
- 1997-03-21 EP EP97908279A patent/EP0889821A1/de not_active Ceased
- 1997-03-21 WO PCT/EP1997/001431 patent/WO1997036776A1/de not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3122368A1 (de) * | 1981-06-05 | 1982-12-23 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen | Hydrolenkung |
DE3122368C2 (de) * | 1981-06-05 | 1987-10-08 | Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen, De | |
DE4230960A1 (de) * | 1992-09-16 | 1994-03-17 | Zahnradfabrik Friedrichshafen | Zahnstangen-Hilfskraftlenkung, insbesondere für Kraftfahrzeuge |
Also Published As
Publication number | Publication date |
---|---|
EP0889821A1 (de) | 1999-01-13 |
DE19612872A1 (de) | 1997-10-02 |
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