Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Patent
1989-11-27
1991-08-20
Marmor, Charles A.
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
180147, 180 791, B62D 504
Patent
active
050406310
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to electrically operated booster rack and pinion steering mechanisms of the kind known in the art as set forth, for example, in International patent number PCT/EP 88/00563.
As disclosed in such prior art, an electric motor drives a rack to operate a steering mechanism. The arrangement provides a safety switch which is normally engaged but which disengages in response to a signal in an electrical control circuit or a redundant safety circuit. However, the signal might be erroneous which could result in malfunctioning of the steering mechanism.
SUMMARY OF THE INVENTION
In the present invention, the electric motor is controlled in response to a signal from a torque sensor, i.e. a torque measuring device. Erroneous signals are prevented by a switching device wherein a coupling is normally in engagement with the motor for rotational drive of an axial shiftable threaded spindle drive for the rack by a ball nut connection.
In the event that the torque applied by the driver at the steering wheel does not correlate with a no torque condition of the pinion, shift of the spindle occurs in response to a control circuit due to a steering malfunction. The coupling is opened for disengagement by operation of the switch. The coupling from the motor to the spindle comprises a flexible corrugated bellows to transmit torque from the motor to the spindle for axial shifting and also to compensate the errors in alignment of the train from the motor to the steering rack.
BRIEF DESCRIPTION OF THE FIGURES
Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawing, in which:
FIG. 1 is a diagrammatic representation of the rack and pinion auxiliary steering mechanism according to the invention; and
FIG. 2 is a partial section through the safety switching device of the auxiliary steering mechanism according to FIG. 1, on an enlarged scale.
DETAILED DESCRIPTION
The mechanical part of the rack and pinion auxiliary steering mechanism shown in FIG. 1 comprises a rack and pinion steering gear 1 whose primary part is formed by a pinion 2 and whose secondary part is formed by a steering rack 3. The pinion 2 is connected with a steering wheel (not shown) by a steering shaft connection 4. The steering rack 3 is connected with the vehicle wheels to be steered by steering linkages 5, 6 as is known in the art.
A torque measuring device 7 is installed between the steering shaft connector 4 and the pinion 2. The torque measuring device 7 determines the relative torque between the steering shaft connection 4 and the pinion 2 and controls the driving of an electric motor 8 by an electronic module (not shown).
A ball nut 9 is connected with the steering rack 3 but does not rotate therewith. The ball nut 9 is connected, in driving union, with a threaded spindle 11 by a ball circulating channel 10. The threaded spindle 11 is connected with the electric motor 8 by a coupling or clutch 12 such as an electromagnetic solenoid that is shown only diagrammatically in FIG. 1. The pinion 2, the steering rack 3, the ball nut 9, the coupling 12 and the parts lying therebetween are surrounded by a multipart housing 13.
Referring now to FIG. 2, a drive member or rotor 14 of the coupling 12 is connected with the output shaft 15 of the electric motor 8. However, the drive member 14 does not rotate with the motor shaft 15. An output 16 of the coupling 12 is connected with a flange 18 fastened to the threaded spindle 11 by a spring bellows 17.
The threaded spindle 11 is resiliently supported for axial and rotational movement opposite a bottom plate 23 of the fixed housing 13 by two precompressed elastic intermediate rings 19 and 20 and two axial bearings 21 and 22.
Attached to the threaded spindle 11 is a lever 24 that is axially movable but not rotatable with the spindle. The lever 24 is clamped between one elastic intermediate ring 20 and one axial bearing 22 and held opposite the fixed housing 13.
REFERENCES:
patent: D296798 (1988-07-01), Smith
patent: 2313473 (1943-03-01), Heacock et al.
patent: 3464701 (1969-09-01), Mahoney
patent: 3684285 (1972-08-01), Kane
patent: 3879040 (1975-04-01), Smith
patent: 3884474 (1975-05-01), Harper
patent: 3888487 (1975-06-01), Replogle
patent: 4811813 (1989-03-01), Hovanchak
patent: 4913249 (1990-04-01), Lang
"Original Plato Game", Creative Playthings Catalog, p. 73, 1969.
Knodler Helmut
Lang Armin
Johnson Victor E.
Marmor Charles A.
Zahnradfabrik Friedrichshafen AG.
Zalkind Albert M.
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