DD297795A5 - Parking and maneuvering aid for motor vehicles - Google Patents

Abstract

The invention makes it possible for wheeled vehicles when needed - especially when parking or parking - a special maneuvering for particularly flexible and agile maneuvering in a confined space, u.a. lateral parallel displacement movements, rotational movements on the spot or pivoting movements of the vehicle bug. This is possible without special maneuvering on the chassis, with normal frosted and normally arranged wheels, namely essentially by drive switching in or on the distribution differential. For this purpose, in motor vehicle with four-wheel drive front and rear axles (Fig. 1-4) or right and left wheels (Fig. 5), driven in front-wheel drive vehicle only right and left front wheel with the reverse direction of rotation; In addition, certain steering angles - for right and left wheels u. U. also opposing (Fig. 6-9) - generated, preferably by servomotor track rod length adjustment {lateral parallel displacement movements; Rotational movements on the spot; Pivoting movements of the vehicle; by drive switching in or at the distribution differential}

Description

For this 2 pages drawings

Field of application of the invention

Subject of the present invention is a parking and maneuvering, which should allow for motor vehicles special maneuvering for particularly flexible and agile maneuvering in a confined space, essentially by switching (s) in the mechanical engine (transmission) system of the corresponding equipped vehicle ,

This should u.a. lateral parallel displacement movements of the vehicle (exemplary embodiments: FIGS. 1, 2, 7 and 8), rotational movements of the motor vehicle at the point with the smallest possible turning circle diameter (FIGS. 3, 5 and 6) or at least pivoting movements of the motor vehicle bug with greatly reduced turning circle (FIG 4 and 9).

Such capabilities of a motor vehicle are known not only for obstacle or off-road driving, but also in normal road traffic highly desirable, for. B. for the rapid use of scarce parking areas. Vehicle handlebars come in particular during parking and Ausparken again and again in situations that require difficult maneuvering maneuver in a confined space. As particularly serious examples may be mentioned:

the lateral parking in a narrow, just just the length of the vehicle corresponding niche, or the parking out of an equally short parking space along the edge of the lane when neighboring vehicles were parked under non-compliance with the required minimum distances bumper to bumper, or the parking out of a narrow parking space when parking across For example, at the edge of the road or in parking lots without parking area markings, when the space left behind by other vehicles barely corresponds to a vehicle length behind the rear of the vehicle.

Although such tight parking spaces are inadmissible because of the resulting disabilities, they nevertheless belong to the everyday city life and often make considerable demands on the routine of the driver or become a nightmare for the less experienced driver. In such cases, then the vehicle to be parked centimetrically forward and backward with changing steering angles and then not infrequently in an only imperfect overview of the rear of the vehicle and often on top of that still under time pressure, if namely by the maneuvering the flowing traffic is hampered.

Characteristic of the known state of the art

There has not been a lack of many efforts and attempts to remedy this situation and to provide vehicles with Rangiervorrichtungen that allow a reduction in the turning circle diameter, ideally even turning the car on the spot or a sideways movement (parallel movement) transverse to the longitudinal axis of the vehicle. According to the state of the art, such shunting options either require special wheels or other special ground contact elements instead of the usual wheels (for example, according to Swiss Patent No. 540811, see below, page 3, penultimate paragraph) or in the case of the road vehicles of interest here alone normally frosted wheels - switchable Zusa '^; or hub-turning devices. In the proposals of this kind that have become known so far, however, the realization requires too much technical and cost expenditure, these auxiliary devices must be hydraulically activated as a rule and provided with special drive mechanisms soin. Such devices have therefore been unable to prevail in the Prayis.

Object of the invention

In contrast, the present invention will solve this problem of maneuvering in a confined space with simpler means without such special shunting and, if possible, without any fundamental changes to the chassis, namely alone with the four normal tires tired. This z. As also possible for cars to further increase the maximum steering angle of the front wheels as possible, because such an enlargement would be structurally associated with disproportionate effort and, for example, in cars with unavoidable disadvantages for the space in the passenger and engine compartment. Otherwise, the weight of additional expenditure for the application of the invention should, if possible, amount to at most only a few thousandths of the vehicle empty weight.

Explanation of the essence of the invention

The invention is based on the following basic idea, which, however, first questions the free rolling of the driven wheels and therefore appears to violate fundamental kinematic laws, and thus seems to be at first glance devious:

If one drives in a four-wheeled vehicle, which preferably has four-wheel drive and four-wheel steering, but at least two steerable drive wheels by switching in the transmission system, the front and rear wheels in different directions (I) drives, so with speed ratios different sign acts the traction force components F _x (longitudinal forces) of the front wheels and the rear wheels directed parallel to the vehicle longitudinal axis are now mutually opposed and even cancel each other out with a suitable distribution of torque (FIG. 1); As a result of the traction forces acting on the motor vehicle, essentially only the lateral components F _y (lateral forces) of the driven drive wheels acting transversely to the motor vehicle longitudinal axis remain, and with their help, the drive axles can then be traversed transversely to the motor vehicle longitudinal axis , In this way it is possible, without any other special maneuvering devices are required to move the vehicle with four-wheel drive, four-wheel steering and conventional suspension by generating certain steering angles either parallel to its longitudinal axis sideways (Fig. 1 and 2) or on the spot order to rotate a vertical axis (Fig. 3). But at least the car can, if it has only front-wheel drive and / or front-wheel steering, be pivoted with the bug around the rear axle as a culmination (Figure 4). Analogous effects can also be achieved in that instead of the front and the rear wheels, the right and left drive wheels with different directions of rotation (I) are driven (Fig.5-9), especially if at the same time also opposing steering angles for left and right Rüder or drive wheels can be realized (Fig. 6-9), z. B. by means of a servomotor track rod length adjustment, as explained in Application Example 4. A similar propulsion system with analogue maneuvering capabilities has already been proposed in Swiss Patent No. 540811 (priority of 1970), but only for special vehicles having four specially designed rollers with helical ground contact elements or with four drive wheels having small inclined rotatable discs along their circumference Wearing roles, all driving and turning maneuvers are generated exclusively by varying the speed and the direction of rotation of the four drive elements. In contrast, the present invention uses the normally rubber-tired and, above all, steerable motor vehicle drive wheels and thus ensures the following properties for ordinary road vehicles:

By the above measures, the turning circle diameter in a four-wheel drive vehicle can be reduced to the absolute minimum possible, namely about the vehicle length, but at least for vehicles with front-wheel drive so far that the turning circle diameter at most only about the wheelbase greater than that Vehicle length is. For turning the vehicle on the spot, it is even possible under certain conditions by appropriate opposing steering angles for right and left wheels to ensure a free rolling of the wheels without erasing on the road surface (Fig. 6). The maneuverability and maneuverability of the vehicle can be significantly improved or even optimized by the invention, not only by turning in a confined space, but in particular by the ability to move the vehicle parallel to its longitudinal axis. This possibility not only serves the convenience of the driver of the vehicle so equipped, but is also economically advantageous to the general public, because it allows the faster and more effective use of limited parking areas and also reduces the frequency of damage, u.a. because when entering and leaving the park, the flowing traffic may only be impeded for a short time and not irritated by reverse parking.

The invention is preferably suitable for four-wheeled motor vehicle with at least two steerable drive wheels, esp. For cars, commercial vehicles, buses or all-terrain vehicles with all-wheel drive and four-wheel steering. Aliradantrieb and all-wheel steering are by no means absolutely essential for the application of the invention; However, it results in four-wheeled vehicle, for the equipment already four-wheel drive and possibly even four-wheel steering is provided, u. U. a particularly low overhead for the particularly advantageous application of the invention, for. B. with only one additional reversing gear and a

Servomotoric track rod length adjustment. However, the invention can be applied with equally low overhead, but with not so versatile maneuverability, even with a car only with front-wheel drive and / or only with front wheel steering, (! M Principle, it is also conceivable to apply the invention to single-track vehicles may result in a two-wheeled "two-wheel drive motorcycle with one or two-wheel steering" without any practical significance, but can be used in the theoretical study of the fundamental traction problems encountered to minimize the necessary calculations.)

Since the example of a four-wheeled vehicle with all-wheel drive and all-wheel steering all the only possible components of the traction forces of a four-wheeled vehicle is the easiest way to see and overlook, should initially be assumed in application example 1 of such a vehicle, and initially with opposite direction steering of the front and Rear wheels, so that lateral parallel displacement movements for the vehicle (Fig. 1 and 2) are made possible.

embodiments Exercise booklet 1

Fig. 1 shows the principle of the invention schematically first in the simplest form and illustrates the interaction of all traction forces (driving forces) on the chassis. F ₁₁ , F ₁₂ , F ₁₃ and F ₁₄ are then in the shunting operation according to the invention, the static traction forces of the individual wheels; they each act in the direction of the wheel planes, given by the respective steering angles, the front wheels according to the invention with inlaid first gear of the gearbox in the forward direction, the rear wheels according to the invention opposite, that is to be driven with inlaid first gear in the reverse direction. The front wheels are designated 1 (right front wheel) and 2 (left front wheel), the rear wheels are 3 (left rear wheel) and 4 (right rear wheel). Only later in the application example 4 (page 35) is explained in more detail how the steering angles can be effected for the rear wheels 3 and 4 for shunting operation according to the invention, z. B. by means of servo-motorized track rod length adjustment, and possibly in terms of magnitude and larger steering angle than normal four-wheel steering for the rear wheels (rear-wheel additional steering) usual.

Furthermore, the various parts of the transmission system are shown schematically in Fig. 1: Through the transfer case (center differential) 5, the distribution of the drive torque M _A on the front and rear axle (IVW Mav) takes place in a certain ratio m _hv (= M _Ah / M _Av ); in order to produce a reversal of the direction of rotation for the rear wheels 3, 4 during the special maneuvering operation, this transfer case 5 is, according to the invention, supplemented by an additional reversing transmission, which can also be completely integrated in the transfer case 5 from the outset. For details, see below on page 20 ff. Further, Fig. 1 schematically shows the front differential 6, with which the front axle drive torque M _{Ay is divided} into the right front wheel 1 and the left front wheel 2 nominally in the ratio 1: 1 (F ₁₁ = F ₁₂ = F _lv ), and finally the Rear axle differential 7, with which the rear axle drive torque Mai, on the left rear wheel 3 and the right rear wheel 4 nominally in the ratio 1: 1 (F ₁₃ = F ₁₄ = F _lh ) is divided. The differentials 5,6 and 7 compensate for the different wheel speeds, which come about by steering angles, cornering, etc. come about.

The above findings and the following formula relations derived therefrom are valid on the assumption that friction losses in the differentials 5, 6 and 7 can be neglected and that none of the wheels starts to spin on the given road surface and the possibly present differential locks (eg. in Hinterraddifferential 7) initially not be activated.

For the illustration in Fig. 1 it was assumed that the front wheels are taken 1.2 to the left (in the mathematically positive direction of rotation); the associated steering angle δι, δ ₂ (> 0) for both front wheels differ only by the steering difference angle (track difference angle). The steering differential angle is neglected in the drawing and in part also in the following calculations by assuming O ₁ = O ₂ = δ _ν , where δ _{ν is} then approximately the mean steering angle of the front wheels. On the consideration of the steering difference angle can be dispensed without error anyway, if steering deflections are generated artificially by servomotor track rod length adjustment, as is basically possible for all embodiments (see Example 4). The sum of the two front wheel drive forces F ₁₁ and F ₁₂ , ie the entire front axle drive force F _Av , has the angle δν, possibly taking into account the steering differential angle. The front wheels 1,2 are normally steered in opposite directions to the rear wheels 3,4 in normal four-wheel steering at low speeds; Also for the shunting operation according to the invention in a confined space, namely for the parallel displacement operation shown here in Fig. 1 in the y-direction, ie transversely to the x-direction (direction of the vehicle longitudinal axis, normal straight-ahead direction), the rear wheels are in opposite directions to the front wheels 1,2, d h. here to the right (in the mathematically negative sense of rotation), hit. In this case, the associated steering angle δ ₃ , δ ₄ (<0) for both rear wheels also possibly differ only by the associated steering difference angle, which is partially neglected for the reasons mentioned in the following calculations. The sum of the two rear wheel drive forces F ₁₃ and F ₁₄ , ie the total rear axle drive force F _Ah , then has the angle ö _h ; this corresponds approximately to the mean steering angle of the rear wheels.

From Fig. 1 then arise substantially following in the tire contact surfaces of the wheels 1,2,3,4 acting on the vehicle wheel drive forces F ₁₁ , F ₁₂ , F ₁₃ , F ₁₄ (with DIN-appropriate designations):

F ₁ I = F ₁₂ = Fv static traction forces of the front wheels 1,2 (acting in the direction of the wheel planes (δ _{1 (} δ ₂ )) F _Av resulting static front axle driving force (acting in the direction of the angle δ _ν ),

dismountable in

Fxv = D *. + F _x2 longitudinal force (in x-direction, motor vehicle longitudinal axis) Fyv ⁼ Fy ₁ + Fy ₂ lateral force (in y-direction, transverse to x-axis), F ₁₃ = F ₁₄ = F _lh static traction forces of rear wheels 3,4 (acting in the direction of the wheel planes (δ ₃ , δ ₄ ))

Fm, resulting static rear axle drive force (acting in the direction of the angle δ _h ),

dismountable in

Fxh ~ Fx3 + F _x4 Longitudinal force (in x-direction, motor vehicle longitudinal axis) Fyh = Fy3 + Fy4 Side force (in y-direction, transverse to x-axis).

In addition, especially when sliding or erasing the wheels, frictional forces on the wheel treads, which are directed against the erasing movement; These frictional forces are not shown in the sketch Fig. 1. They work z. B. in the y-direction parallel displacement operation, as it is first considered here, with its resultant against the y-direction (to the right, based on the x-direction facing seating position of the driver) and thereby affect a Parallejverschiebungsbewegung of the Car in y-direction inhibiting; they are further analyzed below (pages 13ff.). In the following, all traction force components F _x , F _y in the x direction (forward) and in the y direction (to the left) are counted as positive, opposing force components (to the rear or to the right) as negative. The torque ratio required for maneuvering

Tlhv = Μαι, / Mav = F, h / F, v

between the rear and front axles according to the invention for the embodiments 1-2 should be negative (m _hv > 0) because in these the rear axle drive torque M _A h and the front axle drive torque M _Av because of the different directions of rotation for shunting operation according to the invention in a confined space should have different signs. The wheelbase I is the distance from the Vorderachsmitte 6 to Hinterachsmitte 7, the gauge b is DIN-according to the distance from the right wheel plane to the left wheel plane (in Oeradeausfahrt), with differences between the track of the front and rear axles not considered here will be, as they are usually only a few millimeters or centimeters in the car. For reasons of simplicity, the influences of camber, spread, caster, etc. are also neglected for the following idealized representations of principles, and also, to some extent, the steering difference angle, if this serves the clarity of the formula relationships.

For the traction forces resulting in Rangierbetrieb invention a resulting longitudinal force component in the x direction

Σ F _x = F _x , + F _x2 + F _x3 + F _x4

= F, _v ((cos δ | + cos δ ₂ ) + m _hv (cos O ₃ + cos O ₄ ))

and a resulting lateral force component in the y direction

Σ Fy = FyI + Fy ₂ + Fy ₃ + Fy ₄

= F, _v ((sin δ, + sin δ ₂ ) + rrihv (sin O ₃ + sin O ₄ )),

where m _hv <0.

If one then adds all the traction forces F ₁ , + F, ₂ = F _Av , F _i3 + F _a4 = F _A h vectorially acting on the motor vehicle, a resulting drive force F is obtained, based initially on the symmetry case on the wheel center 8 as a reference point _A ge., Which attacks at an angle ε to the x-axis or z> - motor vehicle longitudinal axis:

tan ε = IF _y / IF "

= (sinö,

= (cosi + cos O ₂ ) + mhv (coso ₃ + cos δ ₄ )

= approx.

In addition, due to the traction forces, a torque acting on the motor vehicle chassis results about a vertical axis through the wheel center 8, which is often also approximately in the region of the center of gravity of the vehicle.

M (8) "" = F, y (b / 2 ((cos δι - COSO ₂ ) - mhv (cos δ ₃ - COSO ₄ )) + 1/2 ((sin δ, + sinö ₂ ) - m _hv ( sinö ₃ + sin O ₄ ))).

The forces (scalar values) F ₁₃ , F _i4 , F, _h and the associated F _xh component for the rear wheels have in the present example (Figure 1) due to the opposite direction of rotation of the rear wheels negative sign; on the other hand, F ₁ 1, F, ₂ , F, _v , as well as the associated F _m and Fyy components for the front wheels all have positive signs, likewise the F _V h component for the rear wheels (with reversal of direction and at the same time negative angles δ ₃ , δ ₄ , ö _h ). All lateral forces Fyv and _Fyh are therefore positive in the present case, ie they all act in the y direction, ie to the left (relative to the driver's seat position pointing in the x direction).

In order to be able to transmit the largest possible lateral forces F _y , the amounts of the impact angles / δ _ν /, / δ _h / should be as large as possible. By optimizing steering and torque distribution, ie by a suitable choice of the steering shifts to be selected for shunting operation according to the invention and by adapting to the given during this shunting torque _ratio m _hv (or vice versa by adjusting m _hv ), namely by fulfilling the operation

(cos δι + cosö ₂ ) / (cosö ₃ + COSO ₄ ) = - mhv (> 0) «

It can be achieved that the longitudinal forces F _x exerted on the motor vehicle by traction almost cancel each other out: ZF _x = F _x , + F _x2 + F _x3 + F _x4 = F _xv + F _xh = O.

If this compensation condition is met, and thus the longitudinal forces F, approximately cancel each other in the shunting operation carried out according to the invention, the angle of the resulting total traction force against the motor vehicle longitudinal axis is ε = approximately 90 °, ie essentially only the lateral forces F remain _y left, the vehicle is then so in the lateral direction (90 ° transverse to the longitudinal axis) moves, provided that the drive torque of the engine at the given gear ratio is sufficient to bring the wheels during engagement despite their bracing for slow rotation. In this case, not only the frictional forces on the wheel contact surfaces of the wheels, but also the inertia forces caused by the vehicle mass must be overcome. In addition, by the traction forces (without consideration of the frictional forces) still exerted on the chassis a torque about the vertical axis in the wheel center 8:

M (8) ₀ "= F, _v x

(b / 2 ((cosδ, - cosδ ₂ ) + + - (cosδ ₃ - cosO ₄ ))

(COSO ₃ COSO ₄ )

+ | / 2 ((sin,, + sin _{2 2} ) + η- ^ iM .- (SJnO ₃ -sin O ₄ ))). (cosö ₃ COSo ₄ )

The torque share from the second line is assuming equal steering angles of the right and left wheels (δ, = 5j = 5 _V , O ₃ = O ₄ = ö _h ) zero or at least - taking into account steering difference angles - on the move! negligible. If the steering rashes for the special maneuvering operation generated by servomotor track rod length adjustment (see below, Embodiment 4), then the steering difference angle occurring in the normal steering anyway play no role, since the steering angle of the right and left wheels can then be selected independently , The remaining amount of torque from the third row and thus the entire vertical axis torque

M (8) _g "= F,» l (sinö _v + (cosöy / cosöjsinöh)

disappears in four-wheel steering with magnitude equal on all sides equal ("symmetrical"), but front and rear opposing steering angles (Sh = -δ _ν , ie O ₁ = O ₂ = -O ₃ = -S ₄ = S).

At other ratios of the steering angles / 5 _h / 5 _v / as 1: 1 (/ ö _h / </ ö _v /), the high-axis torque M ₀ ,, to zero, if you move it to another reference point 9 on the connecting line between 6 and 7 instead of 8. This reference point 9 has the distance from the wheel center 8

Δχ = I / 2 (tan / δ _ϊ / -tan / δ _h // tan / δ _v / + tan / δh /) (<I / 2)

and can then be regarded as the point of application of the only remaining transverse force Σ F _y : Σ F _y (= F _Ag ") = F, v 2 sinöy (1 + tan / 6 _h // tan / S _v /).

However, this lateral force is only partially available as a driving force for the lateral parallel displacement of the vehicle (acceleration in the y-direction); it is mitigated by the frictional forces of the wheels, which act on these depending on the steering angle partly as circumferential forces, partly as lateral forces, but overall counteract the direction of parallel displacement (y-direction), as will be explained in more detail below.

It is advantageous if the point of application 9 of the lateral force resultant is identical to the center of gravity of the vehicle or can be placed in its vicinity. This is possible if the vehicle's center of gravity is between the front axle (point 6) and Radsiandmittelpunkt 8, as the z. B. in cars with front engine arrangement for at least a small load of the case, such as when driving in city traffic with little luggage in the rear trunk. The vehicle can by the lateral force Σ F _y (= F _Agcl ) when starting z. B. from an extremely tight parking space, which is only a few inches longer than the vehicle length are maneuvered out without forward or backward, namely by a mere lateral displacement (Parallelverschiebungsbewegung) to the left as if all four wheels in a steering angle of ca 90 °. With this variant of the shunting operation, a dream of many motorists is realized. In order to understand this process, which at first sight is astonishing, one can imagine that the centimeter-like forward and backward maneuvers normally required in such cases are effectively eliminated by carrying out these two movements (back and forth with lateral component) at the same time wherein the front axle takes over the drive for the presetting movement and the rear axle the drive for the superimposed reset movement (or vice versa, if, for example, the reverse gear is engaged instead of the first gear, see below in the explanation of FIG. ,

Particularly simple and clear conditions for the lateral parallel displacement movement shown in FIG. 1 obtained when first - only for the invention Rangierbetrieb - "symmetrical" four-wheel steering (ie four-wheel steering with absolute same steering angle for rear as for front wheels considered), again assumed is that for this shunting the steering angle for front and rear wheels are in opposite directions:

sinö ₂ = - (sinS ₃ + sinö ₄ ) (> 0) or

In this coat, according to the above compensation equation (Σ F _x = 0), the torque ratio rear-axle drive / front-wheel drive rrihv = -1 can be made (M _A h = -Mav, with torque distribution 1: 1 between front and rear axle), and it occurs any desired - more or less large - steering angle, the desired compensation of the longitudinal force components F _x , because the compensation equation for each pair of angles IbJ = IbJ is satisfied. In order to obtain the greatest possible lateral forces, of course, the largest possible steering angle δ should be selected. In this "symmetrical" four-wheel steering system, the torque acting on the chassis in the shunting operation according to the invention about the vertical axis in the wheelbase center point completely disappears in this case with opposing steering angles of the front and rear wheels, leaving only a transverse force component acting in point 8 in the y-direction

left, diminished by the frictional forces acting on the wheel contact surfaces partly in the circumferential, partly in the transverse direction, but act with their resultant against the parallel displacement movement. The factor sin δ characterizes the reduction that the overall effective traction forces - even without taking into account the inhibiting frictional resistance of the erasing wheels - in the case of a not sufficiently large steering angle δ experience. If the wheel center 8 is not at the same time also the center of gravity of the vehicle, then the parallel displacement movement is superimposed on an additional rotational movement on the point whose extent and direction of rotation depend on the position of the center of gravity. If it is important to avoid this rotational movement, the ratio of the steering angle IbJbJ and accordingly also the torque ratio / m _hv / for the shunting invention according to the invention must be chosen accordingly different, so that the point of Σ F _v in the point 9 (at a distance Ax from the wheel center 8), which corresponds approximately to the center of gravity of the vehicle:

tan / ö _h // tan / öy / = (1 - (2Δχ / Ι) / 1 + (2Δχ / Ι).

It must be pointed out, however, that the more or less "symmetrical" four-wheel steering (/ δ / = IbJ), if used at all, is only appropriate for the maneuvering operation carried out according to the invention Variable rear wheel additional steering with relatively small steering angles of the rear wheels in question would be an enlargement of the steering angle for the rear wheels, even if the significantly increased space requirements for the wheel arches of the rear wheels could be met in normal driving known for various reasons: z in the case of ö _h = -δ _ν (in terms of magnitude equal, but opposing front and rear wheel steering shocks) would be parked close to the curb or on a wall car when parking front left with the right rear wheel against the curb or with drive the shearing rear against the wall For the understanding of E In the invention, it is helpful to analyze this special maneuvering operation according to FIG. 1 with the conventional methods of motor vehicle technology and to compare it with the "normal" driving operating state because of the engine system modified in the usual way. For the clear case of the assumed "symmetrical" four-wheel steering (5 _h = -δ _ν ), an analysis of the parallel shift _operator can be achieved in a very simple way by a mental artifice:

Namely, the sideways movement of the vehicle of Fig. 1 can also be understood as "forward movement in the y-direction of a chassis in which the illustrated wheels 2 and 3 are the front wheels, the wheels 1 and 4 are the rear wheels; The gauges would be in this way approximately identical to the original wheelbase I. For the four wheels of this considered chassis, which then incidentally have a uniform direction of rotation to the "front" (namely in y-direction), then results in an exceptionally large Slip angle α in the form of positive tracking angle α = 90 ° - δ (or the associated negative toe angle - α = δ - 90 ° with "minus" trace). Foreshortening or toe-out angles are known to result in tracking resistances F _v , which are usually negligible with small slip angles, but can be considerable in the case of large skew angles.

The Nachspurwinkel (slip angle α) are in the above described approach more than 45 °, z. B. in a car with a maximum steering angle of δ = 37 ° α = 53 °, in a bus with maximum steering angle of δ = 79 °, however, only α = 11 °. The wheels can not roll in the direction of the driving forces F, but are forced by the originating from the other axis, inward compensation forces F _x "unroll" in the y-direction, which inevitably in the footprint of the tire in the lateral direction (each perpendicular to the wheel rim plane) an additional erasing must occur.

In the following it will be attempted to estimate the forces which can be transmitted by acting on each tire in the footprint in a greatly simplified manner; these are in terms of symmetry in each case a circumferential force of the magnitude F, (but opposite to the direction shown in FIG. 1) and a counteracting (caused by the opposite wheel of the other axis) compensation force of the amount F _x (= F _av cos δ). If these forces are vectorially superimposed and decomposed into longitudinal components (in the circumferential direction, ie in the direction of the wheel rim plane) and in transverse components (transversely to the wheel rim plane), the desired tire is obtained, neglecting the tire deformations that occur (see below) occurring

Circumferential force (tire longitudinal force) F _u = F, _v - F _x cos = F, _v sin ² ö and

Lateral force (tire lateral force) F, = F _x sinö = F, _v cosösinö.

The traction forces F "acting per wheel in the circumferential direction and by static friction are different from the" normal "driving state (slip angle α = 0 at steering angle δ = 90 °, F _u = F, _v ) by the factor sin ^: ö t'z. in the case of passenger cars SJn ¹ O = sin ^: 37 ° = 36%, in the case of a coach only to sin ² ö = sin ² 79 ° = 96%) - in this case, albeit under great simplifications

Legitimateness is the key to understanding the whole process. Namely, by reducing the effective traction forces, the inhibiting influence of the otherwise normally negligible tracking resistances F _v increasing at increasing slip angles α due to increasing tire deformations increases (see below). If you could increase the steering angle to δ = approx. 90 "(α = approx. 0 °), the normal driving condition with normal static friction would be given for the movement in the y-direction, but without any steering angle (δ -> 0 °). For a proper operation of the special maneuvering method at a car steering angle of, for example, δ = 37 ° sufficient grip of the road surface is required so that the wheels not even in the deteriorated traction conditions The usual road surfaces generally meet these requirements, even when wet and slippery, especially since the invention is preferably applied only in the range of creep speeds.

Due to the deformation of the tire due to the skew (toe or toe), the above-calculated (tire) side force F ₁ is superimposed on yet another side force F, _v independent of the wheel drive force F. This is known to depend on the slip angle α for measurements on individual tires as follows: First, it increases proportionally with α in the case of small diagonal angles of inclination α, whereby the proportionality factor is the so-called. Slip stiffness of the tire is. With larger slip angles α it then increases only degressive, ie, the proportional range is left, and the (tire) side force F, _v reaches a maximum; This is due to the fact that the side force no longer acts in the middle of the tire contact patch, but shifted in the circumferential direction. Depending on the normal force in the tire contact patch and depending on tire and road grip, this maximum lateral force is achieved, for example, at slip angles α between 10 ° (ice cover) and 20 ° (dry road). In the case of the mutually compensating tractional forces θ of the wheels _1, 2 and 3, 4 calculated above, disregarding the tire deformation, the maximum of the traction side forces F ₁ = F _lv cosSsinö = 0.5 F, _v sin 2 at a slip angle α = 45 ° can be achieved. If the lateral forces F, v, caused by the tire deformation, are superimposed, this results in a forward displacement Δα of the lateral force maximum. The y-component (cosö component) of the lateral force is then the associated Spurwiderstaru 'F _v , ie, the counter to the y-direction acting inhibiting force (relative to a wheel):

Fv ~ (F '+ F vcosösinö _a y) cosö = F, _v ² sin a cos a + F, vsina.

Up to larger skew angles α, this trace resistance Fv increases continuously with increasing skew angle α; Therefore, the skew wai'kal α may not be too large, the steering angle δ (= 90 ° - α) for the parallel shift operation so not too small.

When leaving the proportional range of F ₁ V occurs first in the rear of the footprint of the tire a partial erosion, which continues to propagate with increasing slip angle α (ie smaller steering angle δ) forward. At a slip angle α -> 90 ° (δ -> 0 °), the entire footprint would eventually transition to the slip state, always assuming the vehicle movement in the y direction; The slip would then go to 100%.

In the "y-direction" skid, a lateral erasing speed inevitably occurs at the footprints of the tires, which is associated with lateral slippage λγ = sina = cosö; For example, in a car with naximalem steering angle δ = 37 °, this slip is still 80%, with smaller steering angles it would be even greater, in a bus with maximum steering angle δ = 79 °, the slip is only 19%. The transversely to the wheel rim planes acting outwardly unusually large static lateral forces F, - among other things, as a result of the corresponding component of the compensation force F _{x of} the respective opposite wheel of the other axis - thereby deform the tires elastically; It is understood, of course, that the tires are dimensioned and tuned to the rims so as to withstand the increased tire side forces F, as compared to normal operation, and that the tires can not jump off the rims, even with reduced tire air pressure , Too little ejection resistance must be avoided if necessary by using more suitable rims or a more suitable tire / wheel system.

With the unusually large skew angles of z. B. α = 53 ° (in a car with a maximum δ = 37 °) and the consequent erasing and flexing of the tire is of course associated with greater wear compared to normal driving. The additional Reifenvorschleiß in a zurückieregenden shunting distance of z. B. 2-3 meters holds but within limits, since the Rangiervorgang is handled in the Boreich of creeping speeds. Comparatively, the wear is much lower than that which z. B. would normally be expected if the same car is decelerated at a distance of equal distances of 2-3 meters on the same ground with blocked wheels (from low speed to a stop); In addition, the wear is distributed more evenly over the entire tire circumference. After all, the inventive method of maneuvering in a confined space because of: higher tire wear and increased fuel consumption only in case of need and not unnecessarily often be applied, in particular not then weiin enough time, space and routine for normal shunting maneuvers available. Otherwise, tires, rims and gears would have to be dimensioned correspondingly more robust from the outset, especially when using this special shunting operation not only as a pure parking aid but to increase the maneuverability of an off-road vehicle or the like.

In contrast to Fig. 1, in which the vehicle ι. B. was offset parallel to the left when parking, Fig. 2 shows the analog operation with parallel shift to the right, z. B. when parking. Here, the signs of the steering angle are reversed (δ _ν = -ö _h = δ <0), and accordingly receive all side forces F _y and, accordingly, the resultant Σ F _y - 4 F, _v sin δ negative instead of positive sign. The vehicle is accordingly offset parallel to its longitudinal axis to the right, as z. B. would be required for parking in a parking niche, which corresponds just just the Fahrz suglänge. A parallel displacement movement of the vehicle to the right could also be achieved with wheel positions shown in FIG. 1, namely when the reverse gear is engaged for the shunting invention instead of the first (forward) gear and thus the front axle in reverse, the rear axle is driven in the forward direction , Both methods are in principle equivalent, unless the stronger ratio of the reverse gear is even considered more advantageous.

Compared with FIG. 1, the directions of all driving forces and their components and accordingly also the direction of parallel displacement would then be reversed. The side forces F _{1 of} the tires (transverse to the wheel rim planes) which occur during the sideward movement due to the large slip angles would now no longer be directed outwards, but inwards; instead of large tracking angles (with "minus" track), large toe-in angles (with " Plus "track), unlike Fig. 1, the tires would be deformed in exactly the opposite direction, and also the lateral force maximum shift Δα would have opposite signs. Conversely, a parallel displacement movement of the vehicle to the left can also be achieved with Radstellun jen of FIG. 2 by engaging the reverse gear (with reversal of direction of all driving forces and their components and of course the direction of movement in Fig. 2).

Cont'd. Ausführungsbelsp. 1

(Motor vehicle with four-wheel drive and steering, rear wheels driven in opposite directions, but steered in the same direction to the front wheels, Fig. 3) A second possible variant of the method - initially still in the context of the embodiment 1 for a motor vehicle with four-wheel drive and four-wheel steering - show; NG.3. In contrast to FIG. 1 and FIG. 2, in this variant, the rear wheels are steered in the same direction as the front wheels for the maneuvering operation according to the invention, ie, the steering angles δ _ν , 5 _h are given the same sign, ie in the case of FIG Special maneuvering applied "symmetrical" four-wheel steering applies:

In this variant of the method, when the longitudinal forces F _x cancel each other again, the side forces of the front wheels Fyv positive, the rear wheels F _yh negative, so oppositely directed, so that the car no parallel _{displacement movement} , but approximately a rotation on the tunnel 3, in the mathematically positive direction of rotation (counterclockwise) about a vertical axis about the wheelbase center point 8. Thus, the turning circle diameter, which is normally 10-12 m for a 4-5 m long motor vehicle, to the theoretically possible minimum, namely laterally rounded bumpers almost to the vehicle length, in any case to less than 50% of the normal turning circle diameter, has been reduced. The resulting total traction force F _Aoe i is 0, but a correspondingly large torque is generated about the vertical axis in the center of the wheelbase 8

M (8) _g "= 2F. _Y lsinö,

which acts on the vehicle chassis and leads to the rotational movement. However, the wheels 2,4 radiate much more than the wheels 1.3 on the road surface, as can be seen in Figure 3. because namely the slip angle α of the wheels relative to the respective tangent to the track circle 10th

0.2 = CU = arctan (l / b) + δ α, = da = arctane (l / b) - δ

amount are different in size: When left turning of the front wheels δ> 0, if the track width b substantially exceeds the wheelbase (I> b) are the wheels 2.4 more or less perpendicular to the track circle tangent, so that these wheels contribute virtually nothing to the vehicle rotary motion , In the case of Ia ₁ I, / O ₄ / § 90 °, the wheels would even 2,4 erase against the vehicle rotary motion, unless this is compensated by the Vorderachs- and Hinterachsdifferentiale 6 and 7. At skew angles of z. 8. On the order of 90 ° results from the tangential to the track 10 directed lateral frictional force components of the erasing tire 2,4 a significant inhibition of rotational movement. However, these inhibiting sliding friction forces are overcome by the traction forces of the driving wheels 1, 3, which are applied predominantly by static friction, so that rotation, although with low efficiency, takes place on the spot. This results in the wheels with the large skew angle '' n possibly along the circumference uneven tire wear, especially in unlocked differentials 6 and 7; Under certain circumstances, it may be advantageous to lock the differentials. In order to avoid these differences in the slip angle and in particular the inhibitions of the rotational movement caused by the wheels 2.4 and thus to optimize the turning operation, these wheels 2.4 would have to be driven in opposite directions and be driven in the opposite direction (cf. 6).

In the present case (FIG. 3), if all the wheels are turned in opposite directions (change of sign for δ, δ <0) compared to FIG. 3, or if the reverse gear is engaged (change of sign for all driving forces and their components), the vertical axes occur -Rotation in the reverse direction, ie now in mathematical necative direction of rotation (clockwise). The reversal of this Hochachsen-direction of rotation by reversing the steering angle - but not by engaging the reverse gear - has the consequence that then no longer dia wheels 2,4, but the wheels are approximately 1.3 transverse to the track circle tangent and erase accordingly stronger.

The invention is, as already stated, particularly suitable for use on four-wheeled motor vehicles in which all-wheel drive and also all-wheel steering are already provided, e.g. also for off-road vehicles. All-wheel drive and four-wheel steering are desirable for normal cars desirable security features, but they do not bring on their own so blatant advantages in everyday use that the large mass of car buyers would be willing to pay for these benefits a significant increase in the price of the vehicles The invention makes it possible for a relatively small additional effort in the vehicle with four-wheel drive and four-wheel steering mitzuliefern even the frappante solution of an everyday problem, namely the maneuvering in confined spaces, to the lateral parallel displacement movement and the rotational movement of the car on the spot. Since with such capabilities of a car practically a dream of many car drivers is realized, the invention is also particularly suitable as a supplement and as an additional selling point for the safety four-wheel drive and all-wheel steering. But it is also for cars, e.g. only with front-wheel steering, possibly even with front-wheel drive applicable (see w liter below, embodiments 2 and 4, Fig. 4 and 9).

For the practical realization of the invention, it is usually necessary or expedient to divide the driving torque between the front and rear axles in defined catfish for the planned shunting optionally in four-wheel drive and possibly in four-wheel steering the ratio of the steering angle of the front and rear wheels accordingly adapt. The steering angles for the rear wheels required for "special" maneuvering in the case of "symmetrical" four-wheel steering (/ ö "/ = / δ _ν /) would be much greater than for normal four-wheel steering (so-called rear-wheel additional steering) are relatively easy to implement by means of servo-motorized track rod length adjustment (see embodiment 4), but usually require more space for wheel arches, etc. At the end, the otherwise necessary additional expenditure for the invention would only exist in such a equipped vehicle that in addition to Transfer case (intermediate or center differential 5, or integrated in this transfer case) a reversing gear is provided, which causes the direction of rotation reversal for the rear axle for the intended special maneuvering in a confined space.

This reversing gear (speed ratio usually i = n _h / n _y = -1) then gives, together with the other transfer case the desired in this case negative torque ratio m _hv = NWMav This reversing gear consists z. B. in the simplest case according to a well-known model essentially of two sitting on the output shaft bevel gears, which are driven in opposite directions by a transverse to third bevel gear, and from a scha 'ungsbetätigten turning sleeve which selectively couples one of the two bevel gears with the output shaft. In addition, there are elements if a coaxial instead of an angular arrangement of the drive and output shafts of the reversing gear is to be ensured. If the switching of the reversing gear can also be done while driving, z. B. for temporary improvement of maneuverability in off-road vehicles, so a lock synchronization is appropriate. When using the invention as a pure parking aid, however, the operation of the reversing gear can be limited to a standstill and the switching device are carried out according to simple; In this case, however, an additional provision is advantageous, which allows the switching of the reverse gear - and coupled with the servo motor magnification of the steering angles for the rear wheels - only at standstill and also only when the first (forward) gear or reverse gear.

Elegant and space-saving is the integration of the reversing gearbox in the associated transfer case (center differential) 5. For such a selectively switchable direction of rotation reversal, there are numerous solutions, such. B. according to known model with intermediate wheels, so that the execution of further details is unnecessary. It is advantageous for the shunting operation according to the invention u. U. an even stronger translation; For this purpose, a correspondingly dimensioned additional forward and reverse gear (creeping speed gear) may possibly be provided for this shunting operation or a much more geared reverse gear in conjunction with a separately shiftable reverse gear.

Is in the described variants of embodiment 1 (Figures 1, 2 and 3), the four-wheel steering with respect to the amounts of steering angles in the shunting invention not "symmetrical" (/ ö _h / = IbJ) ₁ but only as in normal operation as Hlnterachs additional steering (/ öh / < / 6J) ₁ and the steering angle of the rear wheels for this maneuvering not much larger than four-wheel steering in normal driving or maneuvering be, so that no particularly large wheel arches for the rear wheels 3,4 are required then the desired compensation of the longitudinal force components F _{x can} normally only occur at a specific steering wheel position defined with certain associated steering angles δ _ν , δ _h , depending on how the constant torque _ratio m _{hv was} chosen for the shunting operation according to the invention Rangierbetrieb a locking of the steering in the Of course, the rear steering angle is of course not chosen too small, because otherwise the side forces Fyv and _Fyh amount to be different and then real lateral parallel _{displacement movements} (Fig. 1 and 2) or real rotary movements on the spot (Figure 3) may no longer readily possible, but possibly only mixed forms, eg. B. in the limiting case, when the rear axle is not steered at all, only pivotal movements of the vehicle bug (see below, Embodiment 2, Fig. 4). Basically, then according to the compensation equation (Σ F _x = 0)

cosot + cos5 ₂ / cos6 ₃ + cos5 ₄ = -m ^ v

the torque _ratio m _hv for the shunting operation _according to the invention amount to be less than 1, because in general also (cosδι + COsO ₂ ) will always be less than (cosöa + COsS ₄ ); This means that in this shunting the front axle - the amount - larger drive torque, the rear axle must receive the smaller, z. B. in proportion

/ m _hv / = 0,80,0,82,0,87,0,05 etc.

At front middle steering angle for a car of z. B. / δJ = 37 °, this could be done with rear mean steering angle of

/ ö _h / = 3 °, 13 °, 23 °, 33 ° etc.

to reach. A center differential S is required to with a special at / 5 _h / <IBJ usually in amount of 1: 1 deviating nominal torque ratio in ^ ₁ I. For this purpose a suitable planetary gear differential 5 is suitably used, if necessary, with optional switchable Torque _ratio m _hv , this is different for normal operation and for special maneuvering, possibly also for parallel shift operation and for rotary operation. In this center differential 5 then also the device for reversing the direction of rotation for the rear axle (reversing gear) can be integrated.

If the compensation condition Σ F _x = 0 is satisfied by m _h v = - (cosöy / cosöh) in the case S ₁ = δj = δ _ν , S ₃ = O ₄ = δ _h, the result is the use of asymmetrical four-wheel steering (/ 5 _h / < 15J) significant differences in the lateral forces on the two axes:

Fyv = Fyj + Fy2 = 2 F ₁₇ si η δ _ν Fyh = Fy ₃ + Fy ₄ - -2 F, v (cos6 _v / cos5 _h ) sinö _h ; they differ by factor

This has the consequence that the Parallel-Traktionskraft (Fig. 1, δ _ν > 0.6 _h <0), the total traction force F _Age , instead of in the wheel center 8 in a by the distance Δχ more shifted to the front axle reference point 9 attacks:

Δχ = I / 2 ((/ t £> nö _v / - / tanö _h /) / (/ tanö _v ) / + / tanö _h /)).

The closer this reference point 9 is to the center of gravity of the vehicle, for example in the case of a motor vehicle with a front engine arrangement, the more favorable; otherwise, a significant additional rotational movement may be superimposed on the parallel displacement operation. Likewise, according to this method, no pure turning operation will be possible on the spot (FIG. 3, δ _ν > 0, δ _h > 0) because boi fulfillment of the compensation condition Σ F _x = 0 is not simultaneous

Σ F _y = 2F, _v (sinö _v - (cosöv / cosöhJsinöh)

Can be zero; this would presuppose / δ, / = IbJ ₁ thus "symmetrical" four-wheel steering, if one starts with the same steering angle for right and left wheels. (With unequal steering angles for right and left wheels, Σ F _v = 0 can be guaranteed at the same time Corresponding embodiments will be explained below.) Therefore, in this embodiment 1, the vehicle in asymmetrical four-wheel steering instead of a pure rotary motion on the spot a rotational movement with a superimposed Seitwärtsbowegung (in Fig. 3, first to the left) execute if no further remedial action is taken This sideways movement is due to the fact that the rear axle is not pulled as _far to the right as the front axle by the traction _{force component} F _^ acting there because of the lower traction _{force component} F _yh acting there continuously changing in rotation of the vehicle continuously changed; it changes from the initial y direction after a quarter turn (90 °) in the minus x direction and after reaching a half turn (180 °) in the minus y direction. If one compares after such a half-turn initial and final position of the vehicle, this is, apart from the rotation (sweeping), in the direction of the original minus-x direction, ie in the direction of the original longitudinal axis has been moved. The vehicle has thus carried out a pivoting movement about a pivot point which lies between point 7 and 8. (In the case of IbJ - / δ _y /, this fulcrum is identical to the marginal center 8 (FIG. 3), in case / ö _h / = 0 to point 7, as will be explained in the next embodiment 2.)

The superimposed vehicle displacement in the direction of the original x-direction can be taken into account by permitting an oppositely directed longitudinal movement in the x-direction from the outset for rotary operation, ie not making Σ F _x zero. However, this then again because of the continuous rotation of the vehicle an additional lateral displacement of the vehicle in the direction of the original y-direction result. Instead of compensating for the longitudinal forces, as is done by satisfying the condition m _hv = - (cos ö _v / cos ö _h ), it may be more favorable during the rotational movement to reduce or even completely compensate for the lateral forces (Σ F _v = 0). To ensure the latter, one would have equal amounts of lateral forces on the front and on the rear axle

Fyv = F, v 2 sin δ _ν Fyh = F. »2 m _hv sinöh

bring about; this would be a torque ratio for rotary operation

Tihv = - (sinö _v / sinö _h ) require <- 1, and it would then result in a non-vanishing longitudinal force

ΣF _x - F _lv 2 (cosö _v - (sinOv / sinö _h ) cosö _h ) = F _lv 2cosö _v (1 + / tanö _v / tanö _h /)

result. However, this would have the consequence that the rotational movement superimposed on an additional, initially in the original x-direction beginning longitudinal movement and the vehicle therefore requires a little more space in front of the bow on the left side (at δ> 0). The car will then have been displaced in parallel after execution of a half turn in addition to the turnaround, in the direction of the original y-direction.

Between the two conditions ZF _x = 0 and Σ F _v = 0, which according to the above relationships - with left and right same steering deflections - only in symmetric four-wheel steering (/ δν / = / öh /) can be shared, can in asymmetrical four-wheel steering (/ &, /> IbJ) a compromise meeting the desired requirements can be concluded. Even more options are obtained if different and possibly even opposing steering angles are generated for right and left wheels, for example by means of servomotoric tie rod length adjustment, as will be explained later in Application Example 4.

Incidentally, in the maneuvering operation according to the invention, particularly in the parallel shift operation, by the way, when the longitudinal movements of the vehicle are to be suppressed, the compensation condition Σ F _x = 0 does not necessarily have to be satisfied with a corresponding torque _ratio m _hv according to the equation given therefor. The longitudinal movements can instead be automatically suppressed by a self-locking center differential 5, for example a

Torsan differential, or a differential with automatically controlled lock, z. B. with electronically-hydraulically controlled slat lock is used. At slightest speed differences between the front wheels and rear wheels, and zwer regardless of their inventive different direction of rotation, for example, the Torsen differential automatically divides the slower rotating drive shaft to the larger drive torque, so that the same average number of revolutions for Vorderräder- and rear wheels are guaranteed and in this way Longitudinal movements can be suppressed by an automatic adjustment of the torque _ratio m _nv . The suppression of the longitudinal movements is possible in this way even if the compensation condition Σ F, = 0 otherwise (not locking center differential 5) due to the predetermined torque _ratio m _hv and the steering angle ratio / 6 "/ 6 _v / not or only would be almost fulfilled.

Regardless of the center differential 5, it may be expedient to avoid asymmetries, as already mentioned, for various reasons, to provide for the axle 6 and 7 locks, z. B. so that the same shunting the same wheel revolutions of the left and right wheels are forced.

Alternatively, a transfer case 5 with continuously variable division of the drive torque can be used, for example, according to a known model with electronically and / or hydraulically controllable torque _ratio m _hv . For this purpose, for example, serves as a planetary center differential, combined with a viscous lock and a parallel-connected continuously variable transmission (V-belt, thrust belt transmission or the like.); With the infinitely variable transmission, speed differences between the axles can be simulated and in this way the drive torques f * Vh, Mav can be redistributed as required. If such an arrangement is anyway present in a motor vehicle with four-wheel drive and allows stepless redistribution, it makes sense to electronically control or regulate the device equally so that during the special maneuvering operation the longitudinal movements or longitudinal forces F _x or the transverse forces F _y be compensated automatically, ie, for example, the vehicle makes no movements in the x-direction during parallel displacement operation or certain other desired movements in the context of the present invention performs.

Instead of performing the center differential 5 by itself or, as explained above, equipping it with a variable torque ratio m _h »and then switching or regulating accordingly during the transition from normal driving to the special shunting operation, the following substantially simpler alternative may be possible for some applications: You can interpret the reverse gear as a gear and give it for the special shunting a certain, deviating from 1.1 speed ratio IM and also possibly the center differential 5 or additionally also the axle differentials 6 and 7 partially or completely lock. (For example, with 100% locking degree for the center differential 5, then the average center speeds of the front and rear wheels are fully compensated and the driving forces are distributed to the front and rear wheels according to the static friction conditions.) The speed ratio between the rear and front axles i = n _h / n _v vote with the steering angles δ ,, δ ₂ , δ ₃ , δ ₄ for the parallel displacement operation so that in the betr. locked state no motor vehicle movements are performed in the x direction. The constants k _{1 (} k ₂ , k ₃ , Ic <<) for the four wheels (see below) can be determined experimentally and depend on the locked state, torque distribution and friction conditions Although these constants are not the same, they change approximately by the same factor when the road surface or the wheel load changes almost uniformly on all four wheels, resulting in the following calculation for the necessary speed ratio i of the reversing gearbox: The In this maneuvering process, for example with locked center differential 5, the motor vehicle will travel the distance in the x-direction in a differential time period Δt

Δχ = n _v At (kt cos δ, + k ₂ cos δ ₂ ) + n _h At (k ₃ cos δ ₃ + Ic, cos δ ₄ )

return. In order to keep the distance Ax to zero and thus compensate for the longitudinal forces F _x , the reversing gear is to give a specific, possibly deviating from i = -1 speed ratio i, namely

i = nh / n _v = - (ki COSo ₁ + k ₂ cosö ₂ ) / (k3cosö ₃ +

ie with asymmetrical four-wheel steering, the rear axle speed for the special shunting operation is generally to be reduced accordingly. Because of Ax = O are then omitted longitudinal movements of the vehicle, ie the vehicle then performs depending on the selected for shunting and parking steering deflections essentially a lateral displacement of the front and rear axles from, possibly superimposed on a more or less pronounced rotation the position, caused by the Hochachsendrehiiioment. In any case, given a suitably selected speed transmission ratio i, there is always at least one steering angle combination δ ₍ δ ₂ , δ ₃ , δ ₄₎ in which only lateral components of the traction ^c occur.For reasons of neglect and simplifications made in the calculations, it is basically necessary anyway for all dimensions to be taken according to this description for / _hv /, / Sh /, / i / etc., in particular, of course, possibly also, for example, for the design of the blocking characteristic of the center differential 5, corresponding tests are made in order to determine all influencing variables which are given in to take into account the desired vehicle movements.

Incidentally, another alternative possibility of redistributing the drive torques in the special maneuvering operation is simply that either the rear wheels or directly at the center differential the drive shaft to the rear wheels are braked. In particular, if the effective torque ratio / m _hv / was designed for normal operation at least equal to or greater than 1, the desired optimization can be brought about in any case by deceleration in a suitable degree, possibly also using existing ABS components. By this braking the center differential 5 is caused to automatically assign the front axle a higher torque share, ie / m _hv / is accordingly vermindeit and goes in G, enzfall with complete blockage to zero (see Example 6). Also, the various measures listed above can be automatically controlled so that the longitudinal forces F _x or the transverse forces F _{y are} compensated or the vehicle performs only certain desired movements.

Embodiment 2

(Motor vehicle with four-wheel drive and front-wheel steering, front and rear axles driven in opposite directions, Fig.4)

Is now for the car no rear wheel steering provided, but only the usual front-wheel steering, so is in the

above formula relationships 6 _h = 0 to set. This eliminates the lateral force on the rear axle F _yh (= 0). With a suitable choice of

Front axle steering angle

δ _ν = ± arccos (-mhv) = ± arccos (/ m _h v /), or the torque ratio rear axle / front axle m _hv = -c

or if z. B. is to be ranked with completely locked center differential 5, with appropriately selected speed ratio for the reverse gear

i = Πι, / η ,, = - (k, + k ₂ / k ₃ + Ic ₄ ) cosö _v

the longitudinal forces F _{x are} approximately compensated again. In the case of the same constants for the front and the rear wheels k _v = k _h , the compensation of the longitudinal forces occurs when, for the application of steering angles of z. B.

/ δ _ν / = 37 °, 32 °, 27 °, 22 "etc.

the torque ratio rear axle / front axle / m _hv / (or alternatively the speed gear ratio for the gearbox / i / · =)

= 0,80,0,85,0,89,0,93 etc.

is selected. Deviations are possible again when a self-locking center differential 5, z. As a Torsen differential is used.

When properly tuned with the torque or speed ratio steering angle δ _ν then results in the first (forward) gear space-saving swinging the car with the front axle, z. B. with positive steering angle to the left, as if only the side force Fyy acts on the front axle, in turn connected with a corresponding torque about the vertical axis in the rear axle center 7,

M (7) _g , 5 = 2F. _v lsinö _v ,

see Fig.4. When reverse gear is engaged, the reverse process results in the opposite direction. In this process, the vehicle is practically only the steered front axle pulled to the left or right, and it will pivot the front wheels on dom lane 11 in slightly to the rear axle (point 7) as a fulcrum. The Aufaufspunkte of Vordcrreifan move approximately on the track circle 11; the slip angles (between the tangent to the toe circle and the intersection of the wheel plane with the road surface) are for the wheels 1 and 2

Qi = arctane (2l / b) - δα ₂ = arctane (2l / b) + δ,

So are very different and lead to different degrees of erasing the front wheels on the road surface. When the left wheels (δ> 0) turn left, the left wheel is again approximately transverse to the track circle tangent, as in FIG. 3, and can thus contribute practically nothing to the rotational movement; it would even, if only with very little effect, erase against the movement on the track circle 11, as far as that is not compensated by the transfer case, here the front axle differential 6. (It may be useful to lock the front axle differential 6 in order to give both wheels equal revolutions and to ensure more even wear of the tires along the circumference.) If the steering angle is negative (to the right) or the reverse gear is engaged so that all driving directions are correct to reverse, so the processes are reversed in comparison üu Fig. 4 from. In order to avoid the strong erasure of the front wheel 2, which is approximately perpendicular to the track circle tangent, likewise the resulting inhibiting frictional forces, the increased and uneven tire wear and the poor efficiency of this pivoting operation, the left front wheel would have to be turned in the opposite direction to the right front wheel 1 are driven (see below embodiment 5, Figure 9); This makes it even possible to ensure eraser-free rolling of the front wheels 1,2 on the track circle 11 (or 12).

Also in this embodiment 2 space-saving maneuvering is possible, in particular parking and parking at tight parking spaces or turning on slippery road. The toe circle 11 has a radius r, which is only slightly larger than the wheelbase I (more precisely, r = I + bV (oil), the additional member usually makes up only a few percent and therefore can be neglected). Assuming that in a motor vehicle, the front overhang is normally approximately equal to the rear overhang, the approximate law for this pivotal movement is given

Turning circle diameter approx. = Vehicle length + wheelbase,

d. H. the turning circle diameter, which is 10-12 m for a 4-5 m long car for the usual turning, is nevertheless reduced to about 6.5-8 m, ie at least a third.

For the purpose of transition from normal driving operation to the special shunting operation (and / or from the parallel shift operation to the turning operation), the nominal torque ratio rear axle / front axle / m _hv / in the transfer case can again be switched over, if necessary, as already described in the exemplary embodiment 1, by speed overshooting i between the rear - And front axle, locking or Abbremsmaßnahmen or the like. Affected and possibly automatically be controlled so that the longitudinal forces F _x and the lateral forces F _{y are} compensated or the vehicle performs only the desired Parallelverschlebungs-, rotating or pivoting movements. In the limiting case, it is even possible to cause a vehicle with normal four-wheel or front-wheel drive and normal front-wheel steering only by braking measures to a pivoting movement with the bow (see Example 6 at the end of the description).

Embodiment 3

(Four-wheel drive vehicle, with front-wheel or four-wheel steering, right and left wheels driven in opposite directions, Fig. 5)

Another embodiment of the invention is that the longitudinal components F _{x of} the traction forces F, are compensated for the shunting operation according to the invention characterized in that not the front and the rear wheels, but the right and left wheels are driven in different directions of rotation. 5 shows the example of a four-wheel drive vehicle in which for this purpose the right wheels 1 and 4 are driven forwards, the left wheels 2 and 3 are driven backwards; This is achieved, for example, via one each the respective differential gear 6 and 7 associated or in this integrated reversing gear. If the car via a so-called. Has, drive, are not summarized in the front wheels 1,2 and 3.4 rear wheels each to drive units, but instead right wheels 1.4 and 2.3 left wheels, so even c, '''s reverse gear for the Distribution differential, eg integrated in the output for the left wheels, resulting in the following resulting force and torque amounts for the Traktjonskiüfto:

Σ F _x = F, i ((COSO ₁ - COSO ₂ ) - mhv (cos5 ₃ - Σ F _y = F ₁ , ({sin6, - sinö ₂ ) - m _hv (sinS ₃ - sinö «)) M (8 ) _flM = F _a) (b / 2 (cos0, + cosS ₂ + m _hv (cosS ₃ + COsS ₄ )) + 1/2 (sinS, - sin ₂ + m _hv (sinS ₃ - sin ₄ ))).

At the same steering angle of the front wheels δ, = O ₂ = δ and the rear wheels (δ ₃ = S ₄ , the latter remain pure in pure front-wheel steering anyway, O ₃ = O ₄ = O), for symmetry reasons, both the sum of the longitudinal forces and the transverse forces always zero (Σ F _x = O, Σ F _y = 0), and without that it requires a certain torque _ratio m _hv . This torque ratio

mhv = F, ₄ / F, i = F, ₂ / F, 3

By definition, in the present exemplary embodiment, this is always positive, because the directions of rotation of the right-hand wheels 1.4 are both equal and those of the left-hand wheels 2, 3 are both identical. The torque ratio need not necessarily be 1: 1 (m _hv = 1), but it may be for the special maneuvering a self-locking center differential 5, for example, a Torsen differential, can be used. With this, the drive axle (or with drive Η drive the drive side) would automatically be supplied with more torque at the lower speed. Without taking into account this blocking effect results in a torque about the vertical axis in the wheel center 8 with pure front-wheel steering

M (8) _ge , = F ₁ , b (cos6 + m _hv )

or in the case of symmetrical four-wheel steering (with opposing or the same direction steering angles of the front and rear wheels, St = S ₂ = -δ ₃ = -64 = δ or S) = S ₂ = S ₃ = S ₄ = 6)

M (8) _o "= F" b cosS (1 + m _hv ).

This torque can be reduced by turning the front wheels to the left or right (or possibly also the rear wheels), at m _hv = 1 slightly by 10% and 20% in a car with a maximum steering angle of the front wheels δ = 37 °, By contrast, around 40% or 80% for a bus with a maximum steering angle of the front wheels δ = 79 °. The vehicle then performs, as in Figure 3, a rotational movement at the point in the mathematically positive direction of rotation about the vertical axis in the Radstandmittelpunkt 8, at least if this is in the range of the vehicle's center of gravity. The center points of the tire contact surfaces in the symmetry case describe an approximately common track circle 10 with the track radius r. The rotational movement can be influenced by the steering or by braking, preferably only individual Antriobsseiter axes or wheels, possibly possibly using existing ABS components or the handbrake. The tires etch again on the road, the slip angles are calculated as in Example 1 (page 18), they are in the case δ, = δ ₂ = δ ₃ = δ ₄ = 0 all the same α = arctan (l / b). In the borderline case, if one could realize steerings to / S / - »90 ° with four-wheel steering, the wheels would even be uselessly etched without the vehicle turning. When engaging the reverse gear (reversal of all directions of rotation of the drive) results in a high-axis torque in the mathematically negative sense of rotation (clockwise). In an analysis of the rotational movement, this rotation of the motor vehicle at the point according to FIG. 5, if once apart from the steering deflections δ ,, δ ₂ , δ ₃ , S ₄ (δ _ν = 6 _h = 0), has arisen Think of it as a car where wheel 2 and 3 are the right and left "front" wheels, wheels 1 and 4 are the right and left "rear" wheels, in this fictitious, by cyclically interchanging the wheels The resulting vehicle would then be the y-axis the normal direction, as already in the

Analysis of Parallel Displacement Operation Fig. 1 on page 13 (suppose and all wheels were then normally driven "forwards" (in the y direction), but here in Fig. 5 the motor vehicle is in danger of landing because the "fore" 90 ° to the left, the "rear" wheels 1 and 4 are taken from the y-direction by about 90 ° to the right, this rotation being based on a technical principle, such as Similarly, it has hitherto been practicable only in vehicles with special ground contacting elements (see page 3, penultimate paragraph) or in tracked vehicles, namely, if, for example, the latter were to be rotated on the spot by forward running of the one and simultaneous reverse running of the other track. (In fact, in the case of tracked vehicles such rotation is usually effected by braking a chain.) Compared to the present invention, however, the decisive features of the aussc Hließlichen wheel drive (road contact only on rubber-tired wheels) and the influencing and support option by steering angle of the drive wheels, such. B. in the next embodiment. By suitable steering angles can, as the next embodiment shows a multiplication of the vertical axis torques and also achieve under certain conditions, an almost eraser-free rolling of the tires.

Ai guide belsplel 4

(Vehicle with four-wheel, front or rear-wheel drive, right and left drive wheels driven in opposite directions, right wheels and left wheels and front wheels and rear wheels steered in opposite directions, Fig.6 and Fig. 9 analogous)

The rotational movement of FIG. 5 can be particularly effectively supported and influenced, if one opposing Steering of the left to the right wheels and at the same time preferably symmetrical opposing steering of the Front and rear wheels realized (δ, = -δ ₂ = δ ₃ = -δ ₄ = δ, Fig. Β). As such steering angles in a relatively simple manner

z. B. can be realized by means of servomotor track rod length adjustment will be explained below. You get four-wheel drive

Σ F _x = O

Σ F _y = F, (1 - m _hv ) 2sin

M (8), "= F.i (1 + iTihv) (b cosö + I sinö).

The resultant lateral force resultant Σ F _y can be made zero by m _hv = 1, it can be kept at least negligible kloin, so that there is no significant superimposed parallel displacement movement in the y direction. Compared to embodiment 3 (FIG. 5), here the maximum vertical turning momentum M (8) _a "to be achieved with maximum steering angle δ _{max is} by the factor

cosö _mlx + (l / b) sinö _m , _x

larger, z. As in normal cars usually about a factor of 2, in relatively long vehicles such as buses many times larger. In addition, M (8) _ai can be continuously reduced even by opposing (negative) steering angles and also be made zero with steering angles δ = - arctan (l / b); M (8) _g "can be made negative even by opposing (negative) steering deflections, so that the direction of rotation dor Hochachsen-rotary motion reverses without the reverse gear must be engaged and thus reverse all drive rotational directions.

In Fig. 6, the turning circle 10 (with the turning circle radius r) is registered for the vehicle rotating on the spot. It can be seen from this that the slip angles of the tires 1, 2, 3 and 4 are all the same and relatively small in the case of symmetry; they amount

α = arctan (l / b) - / δ / = arccos (b / 2 r) - / δ /

and are therefore less than 30 ° in normal cars (with maximum steering angles of 37 °, for example). But you can in a car with a relatively small margin or with a very large maximum Lenkeinschiagwinkel as shown in Fig. 6

/ δ / = arct (l / b) = arccos (b / 2 r),

z. B. in a bus with / δ / = 79 °, I = 5.14b, even be made to zero. In this case, then run the intersections of the wheel planes with the Fahrbahnflä jhe tangential to the marked lane 10, so that the wheels during the turning process without large slip angle really "unroll" and the tires as good as not etched on the road surface For example, the maneuverability of small two-seater city vehicles as well as that of semitrailer tractors or buses can be optimized.

The eraser-free rolling can also boi amount different steering angles are guaranteed for front and rear wheels, namely with

/ δ, / = arctane (I - 2 Δχ / b) = arccos (b / 2 r _v ) / ö "/ = arctane (I + 2 Δχ / b) = arccos (b / 2 r _h );

In this case, the vehicle's vertical axis pivot point shifts by the distance Δχ (<0) from the wheel center 8 in the direction of the rear axle (point 7), and the front wheels then roll on a slightly larger track circle 12 (radius r _v ), the Hintsrräder on a smaller Circle (radius r _h ) to the same pivot point (see circle 12, fulcrum 13 and smaller circle 14 as in Figure 9, there, however, without steering angle ö _h the rear wheels 3,4, which then another to the pivot point 7 also can not unroll eraser). In this way, z. B. a tractor unit by arrangement of the rotary joint in the pivot point 13 are designed so that they can rotate on the spot around the hinge, without at the same time also the resting trailer is moved; otherwise such optimal maneuverability would otherwise be possible (at right and left directional steering angles) only with steering angles δ _{ν of} about ± 90 °.

The turning operation with the tangential and eraser rolling on each a circle front and possibly rear wheels can incidentally in the same way also in a car only with front wheel drive (m ^ = 0) or only with rear wheel drive {m _hv = ">, F _a i = 0), in which case, even if F _yh = 0 or FyV = O, the wheels will not roll any other way than given by the steering, as in Fig. 6 (/ ö _h / = / δ _ν /) or Fig. 9 (0 S / ö _h / </ δ J). the economic feasibility of this embodiment 4 (Fig. 6-9) and the following embodiment 5 (Fig. 9) and to the possible variants, however, depends on that For the shunting operation according to the invention, opposing steering angles of the right and left wheels of each drive axle can be realized with only a little effort, this being accomplished most simply by a servo-motorized track rod length adjustment two preferably coaxial, for the purpose of positive guidance mating rod-shaped parts are integrated into these tie rods, namely, for example

1. a hollow bar and

2. a guided therein, sliding rod or the like.,

each one of which contains a rack and the other a driven by an electric or hydraulic servo motor pinion. By driving the pinion, the effective length of the relevant two-part tie rod can be extended, be shortened later by driving the pinion with the reverse direction again. After switching to the shunting operation according to the invention, this drive runs - preferably independent of the previous starting position of the steering - so long until a final contact z. B. on the steering knuckle reports that the wheel in question has reached the predetermined steering angle; after switching off the special maneuvering operation, the drive runs in the reverse direction until a stop contact z. B. at the tie rod reports that this has reached its normal length and the steering again their previous starting position.

This servomotive track rod length adjustment takes place only when the vehicle is stationary or at creeping speeds or low maneuvering speeds; Therefore, it does not cause any significant safety problems, provided that effective measures against unintended operation in normal driving are made. It makes it possible to produce very specific steering angles when required, for example, regardless of the steering differential angles which are indispensable in normal driving operation - exactly equal or opposite steering angles for right and left wheels of a drive axle. It can also be used for the rear-wheel steering (FIGS. 1-3, 6-9) as well as in all embodiments of the invention as power steering also in the front wheels to relieve the driver of the need, even the required steering shunting for the invention Rangierbetrieb manufacture.

Continuation of exemplary embodiment 4

(Motor vehicle with four-wheel drive, right and left wheels driven in opposite directions and directed in opposite directions, front and rear wheels steered in the same direction, Fig.7 and 8)

. The rotational movement according to Figure 6 can also be suppressed in a variant of this embodiment, and instead, a parallel displacement movement can be generated when the steering deflections of the rear wheels in the same direction not chosen in the opposite direction to the front wheels, but with these: δ = -δ ₂ = -δ ₃ = δ ₄ = δ (Figure 7). In this case of symmetrical (front and rear equal, right and left but opposing) steering angles results

IF _x = O

IFy = F, i (1 + m _hv ) 2sin0

M (8) ₀ "= F, i (b (1 + m _h y) cosö + 1 (1-m _hv) SINOE).

If one relates the high-axis torque M _gg , not to the wheel center 8, but to the point of application 9 of the lateral force resulting Σ F _y , which is located from point 8 by the distance Δχ on the connecting line between point 6 and 7, the torque changes compared to M (8) _se to the value

ΔΜ _0Μ = -Fi Δχ 2 (1 + rrihv) sinö.

Since in the actual point of _{application of} the lateral force- _resultant Σ F _y = F _AoM the vertical axis torque must be zero, from this the position of this point of _application can be calculated. If m _hv = 1, this point of attack lies at Δχ = b / (2tanö), ie in the case Δχ> 0 (δ> 0) this point is shifted away from the wheel center 8 in the direction of the front axle point 6, but in the case Δχ <0, δ <0) in the direction of the rear axle point 7 shifted. If m _hv differs from 1, it results with

Δχ = b / (2tanö) - (m _hv - 1 / m _h , + 1) 1/2

an additional shift towards the rear axle. The torque ratio m _hv , which is optionally selected by switching for the rotary operation according to the invention, can be adjusted with the associated steering angle δ depending on its sign (and possibly depending on picking forward or reverse gear) so that the point of attack 9 alone remaining The lateral force resulting Σ F _{y is placed} approximately in the expected vehicle center of gravity and the high-axis torque there is zero.

Whereas δ> 0 was assumed in FIG. 7 and a vehicle's parallel displacement movement to the left was established, when the reverse gear is reversed and all drive directions of rotation are reversed (FIG. 8) or if all steering angles are reversed, a parallel shift movement to the right results.

Because of the center of gravity, it may be appropriate z. For example, a vehicle equipped for turning operation of FIG. 5 or 6 does not allow the above-described parallel shifting operation of FIG. 7 or 8 to be carried out, but instead the one of FIG. 1 and 2 or vice versa for the turning operation of FIG equipped vehicle instead of the parallel displacement operation according to FIGS. 1 and 2 according to FIGS. 7 and 8). In such cases, it would be necessary to be able to reverse either the direction of rotation of the rear wheels (or the front wheels) or the left wheels (or the right wheels). This could be 3 optional

use switchable reversing gears and these ζ. To either the rear axle drive and the drive shafts of the two left wheels, or e.g. the drive shafts of the two rear wheels and the left front wheel, in a car with Η drive z. B. either the drive for the lefton wheels and the drive shafts of the rear wheels or z. B. the drive shafts of the two left wheels and the right rear wheel. Ideal for this purpose, but very expensive, would be a switch from normal four-wheel drive on Η drive; in this case would suffice for the application of the invention 1 or at most 2 reverse gear.

In electric vehicles with Radantriebsmotoren for the individual wheels, such as 4 electric hub internal pole motors, the cost of the reversing gear u. U. be reduced to simple Umpolungsschalter. Due to this separately switchable Umpolungsmöglichkeiten would then in principle - but only in terms of engine switching - the inventive special maneuvering be enabled, z. B. to drive the left wheels with opposite direction of rotation to the right wheels. With the mere possibility or even with the actual implementation of a suitable suitable Umpolungsschaltung, if there should have been something like this already at some point, but would possibly not by any means the present invention with its specific objectives for parking and maneuvering of normal road vehicle with mechanical engine anticipated. In addition to the maneuvering operation according to the invention, there are further decisive features, including the generation of very specific, partly opposing steering deflections of all drive wheels and their targeted tuning either with the torque ratio (eg targeted compensation of all longitudinal forces Σ F _x = 0) or with the wheelbase-to-face ratio (ensuring tangential rolling of the wheels on the toe wheel when turning on the spot).

There are also other simplified variants of the embodiment 4 possible. For example, the right and left drive wheels may be driven in different directions, but only the front wheels are steered. This simplified procedure is i.a. also applicable for vehicles with front-wheel drive only:

Embodiment 5

(Motor vehicle with four-wheel or front-wheel drive, right and left front wheel driven in opposite directions and galenkt opposite, right and left rear wheel unguided, but possibly driven in opposite directions, Fig.9)

Be in a vehicle with four-wheel or front-wheel drive only the front wheels 1,2 oppositely directed and driven in different directions, so would again Schvvenkbewegungen the car with the front wheels on a turn circle 12 (with the radius r _v ) about a pivot point 13 (Fig .9). If it is a four-wheel drive vehicle and the rear axle is driven at the special maneuvering, thereby occurs an additional Hc: hachsen torque of the rear wheels and changed depending on the torque ratio m _hv the position det, fulcrum 13, ie this fulcrum 13 is with increasing torque _ratio m _hv from the point 7 in the direction of the point 8 shifted so that it is the distance Δχ (<0) from the Radstandmittelpunkt 8 away. As a result, the radius r _{v of} the lane 12 of the front wheels is even smaller than, for example, the radius of the lane 11 in Fig.4. While in a car with pure front-wheel drive the pivot point 13 will lie in the rear axle center 7 (FIG. 4, Δχ = -1/2), in the limit case it will be in a four-wheel drive vehicle with symmetrical four-wheel steering (m _hv = 1) in the wheel center 8 (FIG. Fig.6, Δχ = 0). (The calculation corresponds to that of the point 9 in the embodiment 4, Figure 7, except that here the steering angle of the rear wheels if necessary ö _h = 0 are set.) In a car with a relatively short wheelbase I or when using a relatively large maximum steering angle / δ _ν / = arccos (b / 2 r _v ) it is possible as in the embodiment 4, the tires of the front wheels 1,2 also with slip angle a _v = 0, ie without significant etching on the road surface, tangential to the track circle 12 (radius r _v ). Depending on the slip angle αϊ, = / 03 / = Ai ₄ / = arccos (b / 2 rh), the rear wheels would be moved more or less erasing on a concentric smaller circle 14 (radius r _h ) about the same pivot point 13. (In order to roll out of the front wheels and the rear wheels completely eraser, you would have to provide at least one rear-wheel additional steering with suitably selected smaller steering angles 5 _h , as described in Example 4, see above page 34.) This embodiment of the invention can, for. B. in front-wheel drive by means of a servomotor track rod length adjustment (see above page 35) and by means of an integrated in the differential 6 reversing gear z. B. for the left front wheel 2 can be realized. If the rear wheels are to be driven in a vehicle with four-wheel drive during turning operation (with or without the mentioned rear wheel additional steering), then another reversing transmission can be integrated in the differential 7 for the left rear wheel 3; In this case, then the center differential 5 causes compensation for the different bike paths of the rear and the front wheels.

Numerous other embodiments are possible. For the application of the invention, as the above embodiment 5 and also the following embodiment 6 show, by no means necessarily all-wheel drive and not all-wheel steering requirement. With front-wheel drive and front-wheel steering, the purely additional weight-related expenditure for the application of the invention is limited to a few thousandths of the empty vehicle weight and is minimal in comparison with other maneuvering and parking aids which perform similar tasks with wheels or the like.

Embodiment 6

(Vehicle with four-wheel or front-wheel drive and front-wheel steering, blocking possibility for the drive shaft of the rear wheels or for rear wheels)

The following particularly simplified variant, derived from the embodiment 2 is - with normal friction conditions between the tire and the road - although less effective with respect to reducing the turning circle diameter than all other embodiments, but requires no specific and still negative Dreh.'nomentverhältnis m _hv , so no reverse rotation of the rear axle for the special shunting, also no action for the steering system.

In a four-wheel drive vehicle, the opposite drive of the rear wheels 3,4 can be replaced for the special shunting that the entire rear axle is completely "braked" by, for example, the drive shaft from the center differential 5 to Hinterachsdifferential 7 blocks the involved engine and transmission parts are able to cope with the demands of such a gear reduction

Hinterachsantriebs uas drive torque is now assigned by the transfer case 5 the front wheels 1,2, the longitudinal forces F _x are partially compensated by the normal rear wheel drive (m _hv <0) is eliminated and thus only propulsion-inhibiting adhesive or Gleitreibungskräfte the rear 3.4 in Appearance.

The balance between the two rear wheels 3 and 4 on the rear differential 7 is ensured; the transition from static friction to sliding friction occurs only for one of the wheels. (By blocking the rear axle differential 7, the blockage can be extended to both wheels at any time.) Due to the remaining lateral forces Fyv of the only effective front-wheel drive, the car performs a pivoting movement with the nose to the left about the rear axle. Because of the only incomplete compensation of the longitudinal forces F _x , wherein at least one of the rear wheels begins to slide to a considerable extent, this pivotal movement remains superimposed a slight longitudinal movement in the respective x-direction. As a result, the radius of the track circle 11 is slightly larger than the wheelbase, and is comparatively slightly larger than in the method of Figure 4; Nevertheless, the turning circle diameter, especially with good static friction conditions between the rear tire and the road surface, still remains significantly smaller than in normal driving and maneuvering. In principle, approximately the same effect, but without compensation between the two rear wheels 3,4, can be achieved in a front-wheel drive vehicle, if you tighten this acting on the rear wheels handbrake and in this or other ways - possibly through Use of any existing ABS components - the rear wheels 3,4 blocked: When turning the steering wheel z. B. strong to the left would the car with blocked rear wheels then describe the slow Anfahron a slightly narrower arc to the left, as it corresponds to the normal turning circle. This effect is due to the fact that the longitudinal forces F _{xv of} the front wheels 1,2 counteract the frictional forces of the blocking rear wheels 3,4, so that dominate the lateral forces F ^ generated by the chosen front wheels. However, the F "components are only compensated for to an even smaller extent, the static friction of the blocking rear wheels is transferred into sliding friction (unless, for example, a wheel chock is additionally used for at least one of the rear wheels, see below). Incidentally, the above-indicated method of a somewhat "static" cornering crawl with at least one blocked rear wheel is not anticipated by certain "dynamic" methods of handbrake actuation in the curve known from rallying. It is known z. As that rally driver with all-wheel-drive vehicles in a sharp hairpin curve like to jerk the hand brake to force the vehicle faster in the desired opposite direction. Or in safety training is recommended for emergency braking, for example, in certain critical situations, if necessary, by actuating the handbrake and drove around the steering an energy-consuming rotary motion of the vehicle initiate. Such handbrake effects are based on the elimination of cornering forces in blocking rear wheels, but not on a compensation of the longitudinal components of the driving forces and therefore have nothing to do with the present general inventive concept.

In order to ensure the highest possible coefficient of adhesion for the deceleration or blocking of a rear wheel and thus to reduce the turning circle diameter to a minimum, namely about vehicle length + wheelbase, one can preferably makeshift in vehicles that are not equipped for the erfi.idungsgemäßen maneuvering - also Apply the following method: For a pivoting movement of the vehicle bows to the left preferably locked the left rear 3 almost fixed by a wheel attached to this, the tire at a point U-shaped enclosing Radkralle or by a presented chock or the like. Thus, the rear wheel prevented from forward rolling and will describe a small circle on the roadway around the obstacle (wheel claw, wheel chock or the like.) During the further turning process at most still with the tire contact surface of the locked rear wheel. Wheel claw or wheel chock can for example consist of an adhering under load on the road surface lower part and a rotatable upper part for receiving the tire; they are for the purpose mentioned shaped so that even when the vehicle Bug in the course of the turning process (up to at least 90 °, possibly up to 180 °), the rear tire is always locked without being damaged until - after a slight reset of the car - the Wheel claw or wheel chock can be removed again.

Instead of driving the front and the rear wheels or the right and left wheels with different directions of rotation, comes in some cases, an alternative or variant in question such that the different axes (eg, the front and rear axle) or the drive wheels on the right and the left side not simultaneously, but alternately, namely preferably periodically alternately driven. For example, for the purpose of lateral parallel displacement movement of a four-wheeled vehicle (transverse to the longitudinal axis, i.e., in the y-axis direction), certain steering angles are generated and then the front wheels momentarily forward, then the rear wheels momentarily reverse driven, and each alternately repeated. Accordingly, for the purpose of turning the vehicle on the spot, the right wheels can be forward for a short time, then the left wheels can be driven backwards for a short time, etc.

Although the longitudinal movements of the vehicle (in the x-direction) are not compensated for in this method, they remain reciprocating when the drive phases last only a very short time until the next drive change and, accordingly, only very short distances are covered sawtooth-shaped longitudinal movements in the centimeter or at most Dezimeterbereich limited. Strictly speaking, therefore, only the total longitudinal movements executed over a period T of the maneuvering movements are compensated by this method: χ (t + T) - x (t) = 0. In principle, at least all those movements that are listed in the preceding parts of the description are executed, namely lateral parallel displacement movements, rotational movements or pivotal movements of the vehicle, if this has four-wheel drive or front-wheel drive (and at the same time via front-wheel or four-wheel steering). In such a waiver of the simultaneity of the forward and backward movements, although certain disadvantages for the maneuvering caused by the additional running sawtooth-shaped longitudinal movements insofar as this additional time, energy and tire wear is connected. Moreover, in contrast to the solutions listed in the preceding parts of the description, this method inevitably causes the vehicle occupants to be annoyed by additional back and forth movement (in the x direction) as in normal sawtooth parking maneuvers into narrow parking spaces feel. These disadvantages can, however, be outweighed by the following cost-saving advantages for less comfort-oriented applications: The configuration and the dimensioning of the distributor differential (center differential 5), which optionally regulates the torque distribution between the front axle and the rear axle, is then much simpler, since then e.g. regardless of the strength of the steering angle with any one

Torque ratio m _{h ¥} (= fvWM _Av ) can be ranked, about 1: 1 or 2: 1. Because jadas for the otherwise to be complied Kompensationsbedingungen (sum of all longitudinal forces = 0) too large torque can then be compensated by a correspondingly shortened duration of the drive phase for the axis or the betr. Wheel, and correspondingly, any torque too small by a correspondingly extended duration of the drive phase can be compensated. Another advantage of this variant is that it also no longer requires a reverse gear, but can be used for the movements in the reverse direction, because they are carried out alternately with the movements in the forward direction, simply the reverse gear.

Embodiment 7

(Car with four-wheel or front-wheel drive, with front-wheel or all-wheel steering)

An embodiment of this variant, for example, for a car with four-wheel or front-wheel drive and electronically controlled automatic transmission, sielit as follows: There are alternately automatically forward and reverse gear turned on, and the change-time drive z. B. the front axle (when switching on the forward gear) and the rear axle (when switching on the reverse gear) - or in the vehicle with front wheel drive of the right and left front wheel is then simply characterized in that the other axis or drive unit each by a temporary blocking In Betr. output of the transfer case (5 or 6) or blocked by a correspondingly controlled viscous coupling or existing ABS components by braking the betr. Wheels, so that in each case only the drive unit to be driven (axle or wheel side) from the distribution differential (5 or 6) receives a drive torque allocated. Of course, the longitudinal movements (in the x-direction) are carried out as smoothly as possible; this can be done with a suitable acceleration-time curve, z. B. by appropriate control of a viscose coupling or possibly existing ARS components are guaranteed. For example, β '· ι \ can be approximated to a suitable a (t) -acceleration of the acceleration in the form of a sine curve by a periodic trapezoidal function, in each case the duration of the phases with constant extreme acceleration approximately one-third of the period duration, whereby then the first and the second harmonic (2nd and 3rd harmonic Fourier) can be completely suppressed.

The normal conventional lateral parking in a parking space is carried out in vehicles with front-wheel or four-wheel steering known anyway by sawtooth-shaped longitudinal movements (siohe description page 1, last paragraph, and page 11, paragraph 2); Of course, this conventional parking can also be automated with the necessary effort, as demonstrated at the International Motor Show in Frankfurt in September 1989 with the Integrated Research Volkswagen Future.

From conventional Einparkverfahren the present invention, however, differs also in the variant of the embodiment 7 basically in that after the individual sawtooth Längsbewegungsphasen not always changes in the steering angles are required, but that only a single adjustment of the steering angle sufficient for the Rangmenvorgang. In addition, with the latter embodiment of the invention, the longitudinal movements, without thereby the time required for parking is too large, can be kept so small that no sensors for the distance protection are required. The total effort, which is necessary in application of the invention for enabling the special maneuvering operations (parallel displacement movement, for example, for side parking or Ausparkens, rotation on the spot or swing of the vehicle's bow, etc.), by the acceptance of the sawtooth-shaped longitudinal movements and the consequent renouncement of comfort are kept much lower.

Claims (26)

A parking and maneuvering aid for motor vehicles having at least one or two steerable drive wheels, and associated mechanical transmission and steering system, characterized as follows: While the chassis, wheels and tires of the vehicle are conventionally designed without a special parking or maneuvering, a special shunting operation for particularly flexible parking and maneuvering in a confined space essentially by switching (s) in the mechanical drive (transmission) system if necessary allows by these switching either the drive axles, z. B. the front and rear axles, or the drive wheels are driven on the right and on the left side according to the invention in different directions, namely front axle and possibly rear axle with preferably selected torque ratio, First, all traction force components cancel in the direction of the vehicle longitudinal axis (sum of all longitudinal forces = 0) and longitudinal movements of the vehicle are suppressed, and secondly, preferably if at the same time certain same-directional or opposing steering angles are generated, which remain effective on the drive wheels, in the overall effect on the vehicle non-canceling traction forces either as lateral forces (transverse to the vehicle longitudinal axis) all point in one direction and thereby cause a lateral parallel displacement movement of the vehicle or preferably as transverse forces in opposite directions and thereby rotation of the vehicle on the spot cause a vertical axis, with different direction of rotation of the right and left wheels also have without steering angles as longitudinal forces in opposite directions and thereby also cause a rotation of the vehicle on the spot, or as different sized forces on the front and rear gl eichzeitig cause parallel displacement and rotation of the vehicle, so that a pivoting movement preferably comes about with the vehicle Bug. 2. Parking and maneuvering according to claim!, Preferably for motor vehicles with four-wheel drive and steering, and associated transmission and steering system, characterized as follows: If necessary, for the particular maneuvering operation according to claim 1, the front wheels (1, 2) are opposite to the rear wheels (3, 4), ie. H. driven in the opposite direction of rotation, and to generate the necessary lateral forces either the rear wheels are turned in the opposite direction to the front wheels, so that the vehicle performs more or less only lateral parallel displacement movements transverse to its longitudinal axis, to the left or to the right depending on whether the front wheels (1, 2) to the left or to the right and the rear wheels (3,4) are driven in opposite directions and whether a forward gear or a reverse gear is engaged, or the front and rear wheels taken in the same direction, so that the vehicle approximately a rotational movement at the point in mathematically positive or negative rotation about a vertical axis, but at least a pivoting movement preferably with the vehicle performs BUG, depending on whether the wheels (1,2,3 , 4) are all turned to the left or to the right and whether a forward gear or reverse gear is engaged. 3. Transmission system according to claim 2, preferably for four-wheeled motor vehicle, characterized as follows: For the intended reversal of rotation of an axis, a reversing gear is provided, either integrated in the transfer case or center differential (5) or in addition to this transmission (5), while instead in a car with so-called Η drive, in the right and left wheels respectively Drive units are combined, separate reversing gear for both rear wheels (3,4) are provided. 4. Transmission and steering system according to claim 2, characterized as follows: If necessary, for the special shunting operation according to claim 1 four-wheel steering with a steering angle ratio rear wheels / front wheels of absolute 1: 1 and, accordingly, four-wheel drive with a torque distribution rear axle / front axle of amount 1: 1 is used. 5. Transmission and steering system according to claim 2, marked as follows: If necessary, the torque ratio rear axle / front axle is made correspondingly smaller for the special maneuvering according to claim 1 - with stronger steering angle for the front wheels than for the rear wheels, so that the vehicle can perform the movements provided for in claim 2. 6. Transmission and steering system according to claim 2, characterized as follows: The torque ratio rear axle / front axle is reversible, z. B. by well-known model by a correspondingly executed transfer case (5), preferably by a planetary gear, with switchable load distribution on the rear and front axle, whereby the vehicle if necessary - in the special shunting operation according to claim 1 - with certain steering angles provided for in claim 2 Can perform movements. 7. Transmission system according to claim 2, characterized as follows: The torque ratio rear axle / front axle is kept continuously variable by appropriate design of the transfer case (5) according to the known model and is the case if necessary - for the special shunting operation according to claim 1 or certain variants thereof - controlled so that the motor vehicle provided for in claim 2 movements can perform. 8. Transmission system according to claim 1,2,3 or 7, characterized as follows: If necessary, for the special maneuvering according to claim 1, the center differential of the transfer case (5) completely or partially locked and / or for the reverse gear an amount of 1: 1 deviating speed gear ratio adjusted so that the longitudinal forces cancel each other and thus the Suppression of vehicle movements is ensured in the longitudinal direction. 9. Transmission and steering system according to claim 2, preferably for motor vehicles with four-wheel drive and front-wheel steering, characterized as follows: If necessary, for the special maneuvering according to claim 1 - only the front wheels (1,2) taken and the torque ratio rear axle / front axle selected so that the longitudinal forces cancel at the proposed steering angle, so that the front axle depending on whether the Front wheels are turned to the left or right and depending on whether a forward or reverse gear is engaged, is pulled to the left or right and the car thereby performs a corresponding pivoting movement with the vehicle BUG, in which the front wheels (1,2) on a turning circle (11) are moved about the rear axle center (7). 10. Parking and maneuvering according to claim!, Preferably for four-wheel drive vehicle, and associated transmission and steering system, characterized as follows: If necessary, for the special shunting operation according to claim 1 -the left and the right drive wheels are driven in opposite directions of rotation, for. B. in vierrädrig driven vehicle, the right drive wheels (1,4) forward, the left drive wheels (2,3) backwards, so that preferably the sum of all longitudinal components and the sum of all transverse components of the traction forces are compensated and then the vehicle depending on support, Abbremsung or otherwise influenced by the embossed front wheels (1,2) and possibly rear wheels (3,4) performs a rotary or pivotal movement in the mathematically positive direction of rotation (counterclockwise). 11. Parking and maneuvering aid according to claim 10 and associated steering system, characterized as follows: The steered wheels are not taken in the same direction as in normal steering, but provided to support and influence the rotational movement with opposite steering angles, z. B. the right front wheel (1) to the left, the left front wheel (2) is turned to the right, In addition, if necessary, the rear wheels, if they are also steered, directed in opposite directions to the front wheels, z. B., the left rear wheel (3) to the left, the right rear wheel (4) taken to the right, so that almost a pure rotational motion results on the spot, or instead, the steered rear wheels are not in opposite directions, but in the same direction with the front wheels directed, namely z. B. the left rear wheel (3) as the left front wheel (2) turned to the right, the right rear wheel (4) as the right front wheel (1) to the left 'llagen, so that the car z. B. instead of a rotational movement in the mathematically positive direction of rotation approximately performs a parallel displacement movement to the left (or to the right, if all driving directions or all steering turns are reversed). 12. parking and maneuvering aid according to claim 11, preferably for motor vehicles with four-wheel steering with relatively short wheelbase or large maximum front-wheel steering angle, and associated steering system, characterized as follows: For the special turning operation on the spot according to claim 1, 2 or 11 with opposing steering angles of the right and left front wheels and opposing steering angles of the front wheels and the rear wheels, the steering angle of the drive wheels amount according to the formula / δ / = arccos (track / 2x track circle radius) selected so that all four drive wheels on the common track (10) or the front and rear wheels on different track circuits (12) and (14) are approximately tangential, i. without skew angle and without significant Reifenradieren, can roll. 13. Transmission system according to claim 10, 11 or 12, preferably for four-wheeled motor vehicle, characterized as follows: To generate the direction of rotation z. B. for the left drive wheels ever a reversing gear is used, which is preferably integrated into the associated axle differential, while in motor vehicle with Η drive instead of a reversing gear is used, which is integrated at the center differential in the output for the left wheels. 14. Parking and maneuvering aid according to claim 10-13, preferably for motor vehicles with front-wheel drive and front-wheel steering, and associated transmission and steering system, characterized as follows: By a reversing gear, z. For example, for the left front wheel (2), this is for the special pivoting operation (rotary operation) according to claim 1,10 and 11 - driven backwards, while the right front wheel (1) is driven forward, also an opposing steering angle is generated ( Right front wheel (1) to the left, left front wheel (2) turned to the right), so that the vehicle a pivoting movement with the bow to the left about the pivot point (13) (between the rear axle center (7) and wheel center (8) with the track circle ( 12) (or to the right when the driving directions or the steering angles of the front wheels are reversed), wherein, if the vehicle has four-wheel drive, in addition, for example, the left rear wheel forward, the right rear wheel can be driven backwards, so that the resulting additional high-axis torque of the radius r _{v of} the lane circle (12) of the front wheels may be smaller than the wheelbase. A parking and maneuvering aid according to claim 14, preferably for front wheel drive and front wheel steering vehicles having a relatively short wheelbase or large maximum steering angle, and associated steering system, characterized as follows: For the special pivoting operation (rotary operation) according to claim 1,11 or 14 with opposing steering angles of the right and left front wheel (1,2), the steering angle are in terms of magnitude according to the formula / α / = arccos (track / 2x track radius) chosen so that the front wheels can roll approximately tangentially on a turn circle (12) about the pivot point (13) without skew angle and without significant Reifenradieren. A possibly existing rear-wheel additional steering is preferably designed so that the rear wheels can roll approximately tangentially on a correspondingly smaller circle about the same pivot point (13). 16. parking and maneuvering aid according to claim 1,2,10-13 and associated transmission system, characterized as follows: The transmission system is equipped with, for example, a total of up to 3 reversing transmissions to reverse the direction of either the rear wheels (or the front wheels) or the left wheels (or right wheels) so that z. B. parallel displacement movements of the vehicle preferably according to claim 2 or z. B. Rotations of the vehicle preferably according to claim 10-12 (or vice versa rotations according to claim 2 and parallel displacement movements according to claim 11) can take place; the 3 optionally to be reversed gearbox are z. B. either the Hinterachsantrieb and the drive shafts of the two left wheels or z. B. associated with the drive shafts of the two rear wheels and the left front wheel, in motor vehicle with H drive ζ. B. either the drive for the left wheels and the drive shafts of the rear wheels or z. B. the drive shafts of the two left wheels and the right rear wheel, while suffice to switch from normal four-wheel drive to H drive 1 or 2 reverse gear. 17. Transmission system according to claim 1-15, characterized as follows: As a center differential (5) a self-locking gear is used, for. As a Torsen differential, or a transmission with automatically controlled preferably via wheel sensors lock, z. As with electronically-hydraulically controlled slat lock to distribute for the special maneuvering according to claim 1, the driving forces on the front and rear axle so that longitudinal movements of the vehicle fail or - in a car with Η-drive and self-locking center differential or the like. - Transverse movements of the car. 18. parking and maneuvering aid according to claim 1-17 and associated transmission system, characterized as follows: The special maneuvering operation according to claim 1 is carried out in the more geared reverse gear, or in each case an additional, particularly strongly translated forward and reverse gear. 19. Steering device according to claim 12-13 or steering system and steering aid according to claim 1-18, as follows: To achieve a certain, possibly also opposing steering angle of the wheels of an axle steering ergonomically effective length of the tie rods (or at least one tie rod) is extended by electric or hydraulic servomotors and shortened again, including in this tie rod (s) each z. B. two preferably coaxial, for the purpose of positive guidance mating rod-shaped parts are integrated, namely a hollow rod and guided therein, displaceable rod or the like., Of which each one part contains a rack and the other one driven by an electric or hydraulic servo motor pinion , 20. Steering device or power steering with servomotor track rod length adjustment according to claim 19, characterized as follows: The servomotor drive of the pinion runs in each case - preferably independent of the previous starting position of the steering - so long until a final contact z. B. on the steering knuckle reports that the wheel in question has reached the predetermined steering angle; later, the drive runs in the reverse direction until a stop contact z. B. at the tie rod reports that this has reached its normal length and the steering again their previous starting position. 21. parking and maneuvering method according to claim 1 or 2, preferably for motor vehicles with front-wheel steering and with front or four-wheel drive, and associated transmission, steering and braking system, characterized as follows: In case of need - for the special maneuvering analogous to claim 1 - instead of reversed in the direction of rotation drive the rear wheels at least one rear wheel or each of the rear wheels (3,4) or in a four-wheel drive vehicle instead also the drive shaft for the rear wheels (3, ' ") braked or blocked to at least partially ensure compensation of the longitudinal forces, so that when starting with maximally taken front wheels a pivotal movement of the vehicle with the Fahrzeugbug to the braked or blocked rear axle is possible. 22. A parking and maneuvering method according to claim 21, and associated wheel claw or wheel chock for locking a rear wheel, characterized as follows: To reduce the turning circle diameter is-preferably provisionally locked in vehicles that are not equipped for the shunting operation according to the invention-for the duration of the turning maneuver one of the rear wheels approximately stationary, d. H. Prevented forward rolling, preferably by a wheel attached to this, the tire at a point U-shaped enclosing Radkralle or by a presented chock, so that the vehicle preferably in the course of turning maneuver to the adhering to the road surface lower part of the Radkralle or the Wheel chock is pivoted as a fulcrum. 23. Parking and maneuvering aid according to claim 1 or 2 and associated mechanical transmission and steering system, characterized as follows: Only one steerable drive wheel is used, e.g. B. in a 3-wheeled vehicle only a steerable, arranged in the center front wheel. 24. Parking and maneuvering aid for motor vehicles with at least one or two steerable drive wheels - and associated transmission and steering system -analog claim 1 or 23 or analogous claim 2, 3,4, ... etc. or 20, as follows: The various axles (eg, the front and rear axles) or the right and left drive wheels are not driven simultaneously, but alternately, preferably alternately periodically, so that in the parallel translation, turn, or turn movements not the longitudinal movements or the longitudinal forces (F _x ) are compensated, but only the total over a period T of Rangierbewegungen executed longitudinal movements are close to zero (x (T + t) - x (t) = 0), ie the maneuvering remain small sawtooth-shaped reciprocating movements in the longitudinal direction (x-direction) superimposed. 25. Parking and maneuvering aid and associated transmission system according to claim 24, characterized as follows: A forward and a reverse gear are alternately automatically turned on, and the mutual drive of the front axle (when switching on the forward gear) and the rear axle (when switching on the reverse gear) - or the right and left drive wheels as drive units - is characterized in that the other axis or drive unit respectively by a temporary blockage in the transfer case 5 or 6 or by a correspondingly controlled viscose coupling or by braking Jer betr. Wheels is blocked, so that in each case only the drive unit to be driven, d. H. the betr. Axis or betr. Wheels, the distribution differential is assigned a drive torque. 26. Parking and maneuvering aid and associated transmission system according to claim 24 or 25, characterized as follows: In order to ensure jerk-free reciprocating longitudinal movements, an acceleration-time curve a _x (t) in the form of a possible insijäähnlichen periodic trapezoidal function is effected in the x direction, in each case the duration of Beschicmigungsphasen with constant extreme acceleration approximately one-third is the period so that the first and second harmonics (2nd and 3rd harmonic after Fourier) of a _x (t) become zero.