Steering arrangement for motor vehicles

A steering arrangement for motor vehicles wherein two steerable wheels are coupled with a steering gear arm which is connected to a steering column. The steering gear arm is divided into at least two parts with one part of the steering gear arm being associated with each steerable wheel. At least one sun gear is mounted to the steering column which mates with planetary gears of a pair of planetary gear carriers. The planetary gear of each planetary carrier mates with an outside gear which forms a secondary drive for a part of the steering gear segment arm. A locking device is provided in order to enable an alternative locking of the planetary gear and the outside gear.

The present invention relates to a steering arrangement, and more 
particularly, to a steering arrangement for motor vehicles wherein two 
steerable wheels are, by way of steering rods, coupled with a steering 
gear arm connected with a steering column. 
A steering arrangement of the aforementioned type has been proposed wherein 
a steering gear, by way of a steering gear arm, simultaneously causes a 
wheel turning of the right and left front wheel. The goal of these 
proposed steering systems is to enable the vehicle to meet all the 
requirements of fast straight driving as well as the negotiating of curves 
or turns while nevertheless enabling a turning circle which is as small as 
possible. Sometimes, mutually interfering factors will occur which, for 
example, result in requiring large turning circles or in a so-called 
uncontrolled or unintended engagement of the steering system without any 
action on the part of the driver of a motor vehicle. 
The aim underlying the present invention essentially resides in providing a 
steering system which maintains all of the advantages of a steering system 
in a normal driving situation and yet permits a very small turning circle. 
In accordance with advantageous features of the present invention, a 
steering gear arm is divided such that one part of the steering gear arm 
is operatively connected to the respective steerable wheels, with at least 
one sun wheel, disposed at the steering column, being adapted to engage or 
mate with planetary gears of a planetary gear carrier. The planetary gear 
of each planetary gear carrier is engageable with an outside gear wheel 
which forms a drive for one part of the steering gear arm. A locking 
device enables, on the one hand, alternative locking of the planet gear 
carrier and, on the other hand, a locking of the outside gear of the 
associated planetary gear. 
An advantage of the divided steering gear arm of the present invention 
resides in the fact that the two parts of the steering gear arm, in a 
normal driving operation, are moved simultaneously and by the same turning 
angles. Therefore, the construction of the present invention enables a 
carrying out of all of the normal requirements for a fast straight driving 
of the motor vehicle. However, with an extensive turning of the steerable 
wheels, a separate steering of the two parts of the steering gear arms 
takes place since, when a predetermined maximum turning of the steerable 
wheel on the inside of a curve or turn is reached, a stop becomes 
operative and, by way of a locking device, stops or arrests the respective 
part of the steering gear arm in that position and releases the associated 
planetary gear carrier. However, the steerable wheel on the outside of the 
curve or turn may then, through a turning of the steering column, be 
turned more because the planetary gear carrier associated with the outside 
steerable wheel remains locked and thus only transmits the turning of the 
steering column to the steering gear arm part of the wheel on the outside 
of the curve or turn. The maximum turning angle of the steerable wheel on 
the outside of the curve can thus be adjusted in such a manner that it is 
possible to minimize the turning circle for the motor vehicle. 
In accordance with the present invention, the conventional steering gear is 
replaced by two planetary gear carriers with one or more associated sun 
wheels for dividing the turning motion transmitted by the steering wheel 
through the steering column and, depending upon the turning direction, 
limits the turning angle of one or the other steerable wheels such as, for 
example, the front wheels of a motor vehicle. 
In accordance with the present invention, the locking device includes a 
locking element which, in a first position, arrests an associated 
planetary gear carrier for carrying out a turning movement of the affected 
wheel and, in a second position, stops or arrests the associated outside 
gear at a time of release of the planetary gear carrier. 
Advantageously, the outside gear wheel and/or the planetary gear carrier 
is, in accordance with the present invention, provided with a slide means 
for controlling the locking element. 
In accordance with still further features of the present invention, the 
locking element of the locking device is formed as a bar supported on one 
side and having a free end at which a spring is mounted. 
Preferably, at least one locking device is provided for each planetary gear 
unit and associated outside gear wheel. 
According to the present invention, one unit is provided in one of the two 
locking positions for a control of the locking element of the locking 
means. 
Advantageously, the parts of the steering gear are, in each case, in 
accordance with the present invention, mounted on a shaft with a steering 
gear arm. Moreover, each of the planetary gear carriers is provided with 
several planetary gears. 
Preferably, two sun gears are mounted at the steering column, with the 
planetary gears of one of the two planetary gear carriers being associated 
with the two sun gears. 
Preferably, in accordance with the present invention, the locking element 
of the locking device may be alternatively adjusted into two positions so 
that, in a first position, the planetary gear carrier associated with the 
locking element may be arrested and an oblique or turning motion of the 
associate wheel can be carried out while, in a second locking position of 
a locking element, the outside gear wheel may be stopped or arrested when 
the associated planetary gear carrier is released and thus the gear wheel 
is stopped in the respective final position. 
Accordingly, it is an object of the present invention to provide a steering 
arrangement for motor vehicles which avoids, by simple means, shortcomings 
and disadvantages encountered in the prior art. 
Another object of the present invention resides in providing a steering 
arrangement for motor vehicles which minimizes the distance required for 
executing a complete turning circle. 
Yet another object of the present invention resides in providing a steering 
arrangement for motor vehicles which is simple in construction and 
therefore relatively inexpensive to manufacture. 
A further object of the present invention resides in providing a steering 
arrangement for motor vehicles which functions reliably under all 
operating conditions. 
A still further object of the present invention resides in providing a 
steering arrangement for motor vehicles which accurately limits the 
turning angle of the steerable wheels. 
Another object of the present invention resides in providing a steering 
arrangement for motor vehicles wherein a maximum turning angle of the 
steering arrangement can be readily adjusted.

Referring now to the drawings wherein like reference numerals are used 
throughout the various views to designate like parts and, more 
particularly, to FIG. 1, according to this figure, a divided steering 
system includes a steering column 1 which tranmits a turning motion of a 
steering wheel (not shown) to two sun gears 2, 3, with each sun wheel 2, 3 
being adapted to mate with planetary gear or wheels 4, 5 and 6, 7, 
respectively. The planetary gears 4, 5 and 6, 7 are respectively located 
on planet gear carriers 8, 9 and mate with an associated outside gear 
wheel 10, 11. Each outside gear wheel 10, 11, which may have the shape of 
half of a hollow gear segment, is rigidly fastened to a secondary gear 
drive means 12, 13 for driving steering gear parts 14, 15 (FIG. 2) of a 
steering gear arm arrangement. 
A turning motion, indicated by the double arrows in FIG. 1, is transmitted 
to the two steering gear units generally designated by the reference 
numerals I, II through the steering column 1, with each steering gear unit 
including the sun gears 2, 3, the planetary gear carriers 8, 9, associated 
planetary gears 4, 5 and 6, 7 as well as the outside gear segments 10, 11. 
Thus, two steerable wheels, especially the front wheels of a motor 
vehicle, are each brought into a desired turned or oblique position by one 
gear unit I, or II. Thus, the turning motion of the steering column 1 is 
divided on the two steering gear units I, II respectively formed by sun 
gear 2, planetary gears 4, 5, outside gear wheel 10, and sun gear 3, 
planetary gears 6, 7 and outside gear wheel 11. Each steering gear unit I, 
II of the steering system of the present invention includes a locking 
device 16, 17 with the locking device 16 being associated with the first 
gear unit I and the locking device 17 being associated with the second 
gear unit II. 
As shown in FIG. 2, a bearing 40 is provided for supporting the 
steering-gear arm parts 14, 15, with a steering-gear arm shaft carrying 
the steering-gear arm parts 14, 15. The steering-gear arm shaft is divided 
into shaft sections 18, 19, with the shaft section 18 supporting the 
steering gear arm part 14 and the shaft section 19 supporting the steering 
gear arm part 15 so that they cannot turn. Ball bearings are provided for 
supporting the shaft sections 18, 19 and thereby the steering gear arm 
parts 14, 15. The shaft section 19 includes a cylindrical projection 19a 
engageable in a corresponding cylindrical recess 18a of the shaft section 
18. The shaft projection 19a enables the two shaft sections 18, 19 to be 
rotatable relative to each other and, at the same time, defines the axial 
spacing of the respective shaft sections 18, 19. The shaft sections 18, 19 
of the steering gear arm parts are each rigidly connected to one of the 
secondary drive gear means 12, 13 and cause an adjustment of the steering 
gear arm parts 14, 15 of the steering gear arm as a function of an 
executed turn of the secondary drive gear means, 12, 13. Gear wheels 18', 
19' respectively provided on the shaft sections 18, 19 engage with an 
associated secondary drive gear means 12 or 13. The divided steering 
system of FIGS. 1 and 2 operate in the following manner: 
In a normal driving operation, the planetary gear carrier of the gear unit 
I, which includes the sun gear 2, planetary gears 4, 5, and outside gear 
wheel segment 10, is locked by the locking device 16 so that a turn of the 
steering wheel 1, transmitted through the sun gear 2 and the planetary 
gears 4, 5 is transmitted to the outside gear wheel segment 10. In the 
gear unit II, which includes the sun gear 3, planetary gears 6, 7 and 
planetary gear carrier 9, an operation analogous to the gear unit I takes 
place. The operation of the gear units I, II results in a movement of the 
two steering gear arm parts 14, 15 of the steering gear arm by the same 
angle of turning as a function of the turn of the steering wheel of the 
motor vehicle. 
The maximum turning angle of the steerable wheels in both directions is 
defined in such a manner that the front wheel, which at the time of the 
turn or curve is located to an outside of the curve or turn, executes the 
smallest possible turning circle. If the steering column 1 is turned to 
the point whereat the front wheel in the inside of the curve, for example, 
the front wheel associated with the secondary gear drive means 12, that 
is, the gear unit I, reaches a maximum turning angle the gear unit I, 
reaches maximum turning angle, the locking device 16 becomes operative. 
The locking device 16, associated with the gear unit I, is moved into a 
position illustrated in phantom lines, so as to release the planetary gear 
carrier 8 and stop or arrest the movement of the outside gear wheel 
segment 10. At the other front wheel, i.e., the wheel on the outside of 
the curve or turn which is operated by the gear unit II, the planetary 
gear carrier 9 is stopped or arrested as shown by the solid line position 
of the locking device 17 in FIG. 1. Turning the steering wheel further 
through the steering column and locked planetary gear carrier 9, the 
outside wheel is turned so far to an inside stop that a desired minimum 
turning circle is reached. In case of a turning of the front wheels in 
opposite directions, when the maximum turning or outside stop of the wheel 
is then on the inside of the curve or turn is reached, the planetary gear 
carrier 9 is released and the outside gear wheel 11 is stopped or arrested 
while the planetary gear carrier 8 continues to remain stopped so that 
when the secondary gear drive means is stopped, the secondary gear drive 
means 12 can be moved for the associated part of the steering gear arm 
until the inside stop or something similar is reached which defines the 
minimum turning circle. 
A possible way, the stopping device is working, is demonstrated by FIG. 5 
and FIG. 6. 
FIG. 5 is showing one situation with an arrested planetary gear carrier and 
a free outside gear wheel. Turnings of the steering wheel are transformed 
to movements of the front wheel. This is the operational mode, when both 
front wheels are turned. 
In FIG. 6 the outside gear wheel is arrested and the planetary gear carrier 
is free. Turnings of the steering wheel do not affect turnings of the 
front wheel connected with this gear unit. 
The operational mode is changed automatically by driving the locking bar 
out of the planetary gear carrier slot into the outside gear wheel slot. 
FIG. 3 is demonstrating this changing. The locking bar is just sliding in 
both slots. 
FIG. 3 provides an example of a locking device 16, 17 for the steerin 
system of the present invention. As shown in FIG. 3, a sun gear 2 which, 
for example, may correspond to the sun gear 2 in FIG. 1, is disposed on 
the steering column 1 so as to be rotatable therewith. The sun gear 2 is 
adapted to mate with a planetary gear wheel 4 which, for example, may 
correspond to the planetary gear wheel 4 of FIG. 1. The planetary gear 
wheel 4 mates with an outside gear wheel segment 10 which, for example, 
may correspond to the outside gear wheel segment 10 of FIG. 1 and has the 
respective required shape in order to either form the secondary gear drive 
means for the associated part of the steering gear arm or to be indirectly 
connected to a part of the steering gear arm. 
As shown in FIG. 3, a planetary gear carrier 8, corresponding to, for 
example, the planetary gear carrier 8 in FIG. 1, may take the form of a 
lever which includes sliding surfaces 25, 26 formed with a curved slot 24. 
The outside gear wheel 22 includes a slot or recess 27 which at least 
partially extends vertically with respect to the slot 24. The slots 24, 27 
are adapted to receive a locking bar 16 which forms the locking element 
which, on one side, is disposed in a bearing unit 29 so as to enable the 
bar to move in a direction indicated by the double arrow x. A further 
bearing unit (not shown) is provided for the opposite end of the locking 
bar 16. The direction of the slots 24, 27 are constructed, as a function 
of the turning direction, in such a manner that the locking bar 16, for 
example, because of its own weight, in a normal driving operation, causes 
a locking of a swinging of the lever 8 and prevents movement around the 
axis defined by the steering column 1, whereas, at the same time, a 
movement of the outside gear wheel for the secondary drive of the 
associated part of the steering gear arm is possible. This movement of the 
outside wheel takes place in a direction of the arrow 22' when the lever 8 
forming a planetary gear carrier is stopped or arrested. 
When the front wheel, for example, the front wheel that is on the inside of 
the curve, reaches a maximum turning, the locking bar 16 must release the 
lever 8. The release takes place because of the fact that the outside gear 
wheel segment 10 is prevented from moving in the direction 22' because the 
associated wheel is run against the outside stop (not shown). When the 
steering wheel and the steering column 1 are turned further, the locking 
bar 16 therefore runs up against the guide surfaces 25 of the lever 8 and 
is, with respect to the steering column 1, pressed radially to the 
outside. The locking bar 16 thus reaches the area of the slot 27 and now 
locks the outside wheel 10. On the other hand, the lever 8 is free from 
movement in a counterclockwise direction. Therefore, the steerable wheel 
that is disposed on the outside of the curve may be turned further by 
means of a turning of the steering column 1 with a turning direction of 
the planetary gear 4 being illustrated by the arrows in FIG. 3. 
In the embodiment described hereinabove, the locking bar 16 that forms the 
locking element is, due to its weight and corresponding contour of the 
sliding surfaces 25, 26, at both sides of the slots 24, 27 held in two 
possible locking positions. In lieu of providing bearing units 29 at both 
sides of the locking bar 16, it is also possible in accordance with the 
present invention to, as shown in FIG. 4, support one side of the locking 
bar 16 in a bearing unit with a free end of the locking bar having a 
spring 29 connected thereto and to a stationary fixed part. The locking 
bar 16 assumes the position illustrated in full line in FIG. 4 when the 
locking bar 16 stops the movement of the lever 8 while the locking 
position of the locking bar 16 when the lever 8 is released and the outer 
wheel 10 is blocked or stopped being indicated by the phantom line 
generally designated by the reference numeral 30. 
The one sides bearing support of the locking bar 28 is sufficient since, at 
the time of switching, when the wheel on the inside of the curve runs 
against an outside stop, from one locking position to the other, the 
locking bar 16 travels through a dead center position. 
The function of the locking devices 16, 17 which, may be constructed as 
shown in FIG. 4, resides in locking the associated planetary gear carrier 
when the turning of the steering wheel causes a corresponding turning of 
the associated front steerable wheels into a turned position, or the 
planetary gear is released by the bar 16 and the bar locks the outside 
gear wheel segment 10 when, during a further turning of the steering 
wheel, the affected front wheel is not to be moved. In the latter 
situation, the planetary gear wheel rides on the outside gear wheel. 
As can readily be appreciated, the steering system of FIGS. 1-4 may also be 
constructed so as to utilize a single sun gear instead of two gears with 
the planetary gears of the two planetary sets or planetary carriers 8, 9, 
rotating on the single sun gear. 
While the construction of FIGS. 1 and 3 provide an illustration wherein the 
planetary gear carrier 4 and 9 or 23 only have one planetary gear each, 
designated by the reference numerals 4, 5, 6, 7 and 21, it is also 
possible, as a function of a shape or contour of the outside gear wheel 
segments 10 and 11 to provide more than one planetary gear. 
Additionally, instead of a locking device such as illustrated in FIGS. 3 
and 4, it is also possible to utilize other constructions for achieving 
the desired locking. 
While we have shown and described only one embodiment in accordance with 
the present invention, it is understood that the same is not limited 
thereto but is susceptible of numerous changes and modifications as known 
to one having ordinary skill in the art, and we therefore do not wish to 
be limited to the details shown and described herein, but intend to cover 
all such modifications as are encompassed by the scope of the appended 
claims.