DE1137964B - Steering gear for vehicles, especially with power steering - Google Patents

Description

The invention relates to a steering gear for vehicles, in particular with power steering, in which the steering column shaft is arranged at right angles to the steering wheel shaft and the rotational movement of the steering wheel shaft into a reciprocating linear movement parallel to the axis of rotation of the steering wheel shaft a transmission intermediate member is converted, which is so positively engaged with one with the Steering column shaft rotatably connected coupling member is that the reduction ratio of the transmission changes in the case of lateral steering deflections from the straight-ahead driving position.

A steering gear for vehicles is known in which the steering column shaft by means of a coupling arm into the journal of a steering wheel shaft when the steering wheel shaft is rotated back and forth sliding intermediate member engages. This known transmission changes in the case of steering deflections from the straight-ahead driving position, the reduction ratio, namely in one for the driving style extremely detrimental way by putting the steering in the area of the main used small steering deflections on these small deflections already with relatively large wheel deflections reacted. In contrast, in areas where large wheel deflections are required, for example when parking are, the transmission ratio is so low that the steering wheel shaft rotates over large angular ranges must be to change the wheel position.

In order to avoid these disadvantages, one can make use of the measures that have been customary for a long time which a substantially constant reduction ratio is achieved over the entire steering range. So it is known to lead a nut secured against rotation on the worm, which has a toothing meshes with a toothed segment of the steering column shaft on one of its long sides. The same purpose is at Another known steering gear achieved in that the axially movable on the steering worm Nut has a groove running transversely to its axis, into which a pin of the steering column shaft non-rotatably connected arm engages. This changes with all of these known steering gears Reduction ratio over the steering range practically not.

However, steering gears are already known in which the transmission ratio is in the way changes that the reduction in the straight ahead position is greatest and on both sides this position decreases in the direction of the two end positions. These well-known steering gears however, belong to completely different genera than that which is to be improved by the invention.

Steering gears for vehicles, in particular with power steering

Applicant:

Arthur E. Bishop,

Birmingham, Mich. (V. St. A.)

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Pechmann, patent attorneys, Munich 9, Schweigerstr. 2

Arthur E. Bishop, Birmingham, Mich. (V. St. A.), has been named as the inventor

So a worm steering gear is known, in which the mentioned course of the reduction ratio is achieved in that the pitch of the worm gear in the gear middle position on is smallest and increases on both sides of the middle position. Such snails with changing pitch but represent relatively complicated components that are also manufactured with high precision are expensive.

In another known arrangement there is a toothed segment with a small toothed wheel on the steering shaft with two eccentric guide grooves ending in a recess in engagement. In these Depending on the position, grooves engage two or only one steering finger of the steering lever.

It is the object of the invention to provide a steering gear of the type mentioned in which the Arrangement with formation of the engagement between the linear reciprocating member and the with the steering column shaft rotatably connected coupling member is made so that the reduction - As is known per se from steering gears of other types - in the straight-ahead position is greatest and on both sides of this position immediately and quickly in the direction of the two end positions decreases.

This object is achieved according to the invention in that the positive engagement between the Transmission intermediate member and the coupling member is formed and arranged in such a way that the Intersection of the line of action at the point of intervention

209 660/193

The axis of rotation of the steering column shaft and when the two longitudinal center lines are included Angle is 90 ° '. With this arrangement of the slots, the slot body is also particularly simple Way trained. Its straight slots can be produced with low manufacturing costs. The worm steering gear according to the invention can in principle be operated by hand alone; however, its use is particularly advantageous

transmitted steering force with the axis of rotation of the steering column shaft containing and perpendicular to the linear direction of movement of the intermediate transmission link plane in the straight ahead position the transmission semen has the greatest distance from the axis of rotation of the steering column shaft and at steering deflections approaches the axis of rotation of the steering column shaft immediately and quickly.

The mentioned course of the mechanical reduction ratio has the consequence that the driver io together with a power steering. Another beneficial one in the case of fast straight-ahead travel, in which in the general embodiment is therefore that the pivot common only small steering deflections are necessary to the angle of the slot body and the angle between Steering requires little force and thus the center lines of the slots are so fine on each other Driving experience. In addition, it is agreed that in the transmission end positions jehohe Reduction ratio when driving straight ahead 15 because a slot center line in the plane mentioned the reaction of the steerable wheels on the steering falls. The transmission can also be controlled by the power steering handwheel low. On the other hand, driving is narrow in the case of large rashes, e.g. B. when parking and Berer Curves and when parking maneuvers only one cautiously drive tight curves, easy to operate, nism moderately small number of revolutions of the steering The invention is illustrated below with reference to the schema-

rades necessary. Particularly in the case of parking maneuvers, 20 tables need drawings of an embodiment the driver therefore only explains a few turns of the steering wheel in more detail.

Fig. 1 shows a steering gear designed according to the invention in cross section;

FIG. 2 is a section along the line II-II in FIG. 1

run rades to move the wheels from their one extreme position to the other extreme position.

The worm of uniform pitch can be 25 and shows the steering gear in plan view; manufacture at low cost. Said Ab- Fig. 3 is a section along the line IH-III

the point of intersection of the axis of rotation of the steering column shaft is a measure of the size of the reduction ratio. Accordingly, the sub in Fig. Ϊ;

Fig. 4 is a graphic representation of the operation of the steering gear.

Settlement ratio in the middle position of the transmission in 30 According to FIGS. 1 to 3, this includes according to the invention essentially its maximum and falls on both sides of the trained power-operated steering gear a housing Central position steadily, initially quickly and then 10 as a bearing for a steering wheel shaft 11, a transverse course less strongly. The reduction ratio shaft 12, a worm 13 and a rotating one nis does not change by leaps and bounds at any point. Balls cooperating nut 14. The nut In addition, the reduction begins to fall. 14 also operates in the usual manner with the ratio in close proximity of the gear with worm 13 together, and the rotating balls position. With a deflection of 90 ° from the 15 move along a closed path, the The middle position is the reduction ratio through the grooves 13 a of the worm 13, the grooves 14 a already dropped to a considerably smaller value. the nut and the ball return tube 16 gebil-Das The maximum reduction ratio is therefore 40 det.

only for the very small deflections in straight lines. The nut 14 can counteract in any way

exit while the reduction ratio must be secured with to- rotary movements; with the one behaving here Deflection drops. By the embodiment described first, it is replaced by two rapid and in the further course less strong leads 17 on the inside of the housing 10 so if the reduction ratio is achieved, 45 is supported so that they do not perform any rotary movements

that most of the drop in reduction ratio is near the straight ahead position, so that all wheel deflections close to the straight-ahead position can be achieved with a much smaller steering wheel. In this arrangement is thus caused by a rotational movement of the steering wheel shaft 11 that the Nut 14 over the friction-reducing balls in one direction or the other in such a way.

deflection per wheel deflection are feasible. _{It is moved} away that the bolts acting as cams. Furthermore, the reduction in the reduction ratio, which is firmly connected to the nut, takes place continuously along the length according to the invention, so that the driving experience of the driver is not impaired at any point

move a straight path parallel to the center line of the shaft 11.

will. The cross or steering lever shaft 12 carries one

A transmission with the cam body 21 produced according to the invention with slots 22 and 23, which start in this way Properties can, in principle, be arranged differently in that they are grounded in the drawing Obviously, the types of interlocking stop parts merge with the bolts 20. An advantageous embodiment consists of working; close the central axes of the slots in the fact that the coupling member (hereinafter slot- an angle .4 of 90 °. It is true that a body called) two guide slots each for a 60 angle of this size between the shooters 22 and from the mother laterally protruding pin 23 has proven to be quite useful, but can and that the two contactors and cones (in Ge

drive center position viewed) are arranged symmetrically to the said plane. The mother leaves thus can be implemented as a very simple component which only has two laterally protruding pegs. Particularly advantageous conditions result when the longitudinal center lines of the slots are radial to the

the slots also enclose a slightly different angle, which is evident from the explanation below emerges.

When the parts of the steering gear take their neutral position shown in FIG. 2, the Bolt 20 with the edges 22 α and 23 a of the slots 22 and 23 in contact. The opposite

Walls 22 b and 23 b of the slots end at points 22 c and 23 c, respectively, which are in the immediate vicinity of the associated bolts 20, but without touching the bolts. When the nut 14 is moved together with the bolts 20 in one direction or the other, e.g. B. according to FIG. 2 to the left, engages the toad bolt 20 on the wall 22 a of the slot so as to rotate the cam body 21 and the transverse shaft 12 counterclockwise. After a little

Steering wheel, the high reduction ratio is therefore maintained over a few degrees. The course of the rapid change in the reduction ratio or the change in the angle 5 speed of the rotary movement of the steering force-emitting transverse shaft 12 at a constant The speed of movement of the bolts 20 is of course also reflected in the changing speed Distance between the center line of shaft 12 and

initial movement upon the touch io that point again at which the line of in between the left bolt 20 and the trench wall every moment the power transmission takes place 22 a is due, the right bolt engages 20 center connection line of the contacting Drehan the slot wall 236, and the slot wall 22 cuts a ble parts; at the mentioned force lifted off the left bolt 20. Since the bearing line is usually called the left bolt as it moves to the left of 15 “line of action”, which runs through the the transverse shaft moves away, the trench wall lays contact surfaces between the bolt 20 and the

Side wall of the slot 22 in question extends and which is also referred to as the "common perpendicular" to these surfaces. In the present case, where the bolts 20 move in a straight line or on an arc of an infinitely large radius, the center connection line is formed by the line L which intersects the center of rotation of the shaft 12 and is reduced at right angles to the movement path of the transverse shaft 12 when the transverse shaft from 25 bolts 20 runs. The point at which this neutral position is rotated into one or the other common vertical or the line of the eye limit position. When the steering wheel shaft rotates the center connection line by constant steps and thus crosses it, the reduction ratio of the force nut 14 is in each case transmitted by constant steps. When said line z. B. is moved out of its neutral position, 30 increases in all positions of the force application and the corresponding angle of rotation of the transverse shaft 12 to. Force output members through the same point in which this is apparent when one passes in Fig. 3 with center bond line, the sub B designated angle of rotation between the neutral gear ratio of power transmission between the positioner and one of the two limit positions in nine of force introduction and force output members is constant , equally sized sections along the axis of the steering 35 In the present case, however, the common wheel shaft 11 intersects in a subdivided manner. In the course of the first, here with the same vertical, which is designated in Fig. 3 with N , C designated movement step, the rotation is the line L at a point which is initially fast

22 b does not attack the left bolt, and as a result, the right bolt 20 engages the slit wall 23 b with a swift movement in order to actuate the cam body.

Since the slots 22 and 23 form an angle, the steering reduction ratio or the ratio between the number of turns of the steering wheel shaft and the number of turns of the

angle D 45 ° - Φ; here is tang Φ

-; here in

approaches the axis of rotation of the shaft 12, whereupon a more gradual approach to this axis of rotation takes place,

Reduction ratio correspondingly from a high value first quickly and then more slowly return a lower value.

When the smallest reduction ratio is given, that is, when the power output shaft 12 assumes one of its limit positions a short distance behind the last movement step G , the aforementioned common perpendicular N coincides with the axis of reciprocation

E denotes the total linear movement from the 40 when the bolt 20 gradually moves to the last

neutral position until one of the two limit positions is approaching partial amount G; as mentioned, this goes lungs, and R is the distance between the transverse shaft 12 and the centerline of the bolts 20, along
whose steps of movement of the nut 14 are measured

will. If one proceeds from the above-mentioned division 45 into movement steps, it can be seen that in the first step C there is a rotation of about 4.5 °, that is to say that D is equal to 4.5 °, while the

corresponding angle of rotation when covering

further movement steps increased considerably. During the backward movement of the driving pins 20 together, the last step of the rotary movement, the distance between the center line of the transverse angle G is approximately 8 °, ie the lower shaft 12 and the point at which the perpendicular N represents the settlement ratio of the Steering is only at the middle connection line intersects, according to FIG. 3 it is almost half as large. given by the segment R. In the other extreme case, this change in the reduction ratio is shown in FIG. 4, ie when the greatest reduction ratio for the ratio is illustrated in the drawing. If the straight-ahead travel is given (Fig. 3), the ge transverse shaft 12 runs in one direction or the other from common perpendicular N, which is rotated out at right angles to its neutral position, the line y extends sinks, at an angle B of 45 The reduction ratio rapidly deviates from a value applicable to the opposite of the axis of the reciprocating motion, wheel drive and then goes to 60 and it therefore intersects the central connecting line with a gradually decreasing reduction ratio at a distance X from the central axis of the shaft. Since the points 22c and 23c on the * ~ _, · _A i_ * j i_ -. ·· _ * η «r. R cam body 21 does not abut the bolt 20 ^{12; this distance be} ^ ^{2R or} · 1 ^ 45 ^ ·, the initial movement of the cam takes place The reason for the contact of the appropriately designed steering gear in the position for striking bolt 20 with the slot outer wall 22 a straight-ahead travel is approximately halved and that the or 23 a. In the initial range of the rotary movement of the reduction ratio, that is, the ratio between

the speed of the reciprocating motion and the speed of the rotary motion, twice that is great. Fig. 4 illustrates this change in reduction ratio, which is initially rapid and thereafter takes place less quickly, as explained above.

The angle between the slots 22 and 23 can be varied. This results in other speeds of change of the reduction ratio and a piston pin 29 connected. The piston carries a sheet metal sleeve 30 which is slidably movable in a partition 31. The piston is forcibly guided by the sleeve 30 cooperating with the partition wall 31, so that it can transmit a movement to the transverse shaft 12 via a linkage which is not entirely linear, without the piston tilting in the cylinder 25.
The energy supply to the piston 26 takes place under

ratio in the course of the rotary movement of the transverse io the influence of a hydraulic valve with a

shaft 12. If the angle A is increased, the reduction ratio between the neutral position and the limit positions of the steering gear decreases to a large extent, and vice versa.

As a high steering reduction ratio for driving straight ahead and a considerably smaller reduction ratio for the limit positions of the steerable wheels is provided, you can train the pitch of the screw 13 so that it is in the Piston slide 35, which is slidably movable in a valve housing 36 forming part of the housing 10 is arranged. According to FIG. 2, the piston valve 35 has a centrally arranged groove 37 as well as two outlet grooves 38 and 39, which are shown in dashed lines Drawn bores 42 and 43 are in communication with an outlet channel 40. By doing Valve housing 36 are two grooves 45 and 46 formed, which via channels with the chambers 47 and

Position for driving straight ahead a reduction ratio 20 48 are in connection. One under an overpressure l i lih d üblih hd Söitl id d N 37 über di

ratio that essentially corresponds to the usual values. In view of the described arrangement, which works with slots running at an angle and bolts assigned to them, this slope can be considerably larger than it is usually achieved with a worm and a Provides working steering gears in which the connection between the worm and the the Movement of the screw decreasing member a stagnant fluid is the groove 37 over the Pipeline 49 supplied, and depending on the axial position of the piston valve 35, the pressure medium the chamber 47 or the chamber 48 supplied, while at the same time the other concerned Chamber is connected to the outlet line 40 via one of the two bores 42.

The valve described above is designed in a known manner and is not constant Reduction ratio results, which is part of the invention by 30. You can use the invention Point is reproduced which lies on a line according to the construction, which runs through the axis of the transverse shaft 12 at right angles to the center line of the steering wheel shaft 11. When the various parts in the steering gear designed according to the invention have the above mentioned 35 assume the written position in which the power transmission takes place at a point that lies on a line, which intersects the transverse shaft 12 and extends at right angles to the steering wheel shaft 11, the stands

smallest steering reduction ratio available. This reduction ratio is considerably smaller and therefore to a much greater extent directly than with the previously known steering gears. In the Use of a screw with a large pitch in combination with the cam connection described you need relatively few turns of the steering wheel to turn the steerable wheels move between their limit positions despite the reduction ratio in the straight-ahead position essentially corresponds to the values customary up to now.

In the case of the steering gear described, the steering is done by hand in the area of the limit positions the steerable wheels quite difficult, because in this area the reduction ratio is the Steering considerably smaller. The steering system designed according to the invention is therefore preferably in Used in connection with a Hirfskraftbetäteinrichtung in such a way that the auxiliary power at large Wheel deflections, e.g. B. becomes effective when parking and when cornering slowly, d. H. always then, when tight curves are to be negotiated. For this purpose, a is shown in FIG. 3 in the main housing 10 Power actuating cylinder 25 is provided. From Fig. 2 and 3 it can be seen that in the cylinder 25 a Piston 26 is arranged to be reciprocable; this piston is through with the cam body 21 use a crank pin 27, a connecting rod 28 big valve, which is under the influence of the Steering torque. The particular construction of the valve described here is only an example consider.

The piston slide 35 is by the engaging on the cam body 21 bolts 20 in one or other direction. When a steering force is applied to the transverse shaft 12, the movement the nut 14 opposes a resistance. This resistance causes the steering wheel shaft to move 11 moves against the action of the balanced disc springs 50, which together with the races 51 and 52 and the bearing balls 53 form a bearing for the steering wheel shaft and when applied allow a steering force on the transverse shaft 12 a limited axial movement of the shaft 11.

When using the steering gear designed according to the invention, a rotary movement calls the Steering wheel shaft 11 thus results in a rotary or steering movement of the transverse shaft 12, which is caused by the described, working with a variable reduction ratio, the two bolts and the two slots comprehensive arrangement is conveyed until a steering load is applied to the transverse shaft 12 which is sufficient in order to generate a reaction force on the nut 14 which overcomes the force of the springs 50 can. As soon as the springs 50 are bent, the piston slide 35 moves to the left or right, so that the pressure medium is directed to the piston 26, which in turn via the crank pin 27 an operating force on the cam body 21 brings up. Thus, the use of a screw with a large pitch becomes necessary for one in the limit positions of the steerable wheels considerably reduced reduction ratio by that of the hydraulic Motor delivered actuation force more than balanced. The invention thus enables the

Number of turns of the steering wheel that are required to move the steerable vehicle wheels between their stop positions to turn, to reduce considerably, while at the same time a lighter gear of the steering gear is achieved without the driver being affected by the presence of a small steering reduction ratio in the area of straight-ahead travel is at risk and without the driver having to exert a greater steering force the steering wheel needs to bring up.

Claims (6)

PATENT CLAIMS: 1. Steering gear for vehicles, in particular with power steering, in which the steering column shaft is arranged at right angles to the steering wheel shaft and the rotational movement of the steering wheel shaft is converted into a reciprocating linear movement of a gear intermediate member running parallel to the axis of rotation of the steering wheel shaft, which is in such a form-fitting engagement with a coupling member connected to the steering column shaft in a rotationally fixed manner, that the reduction ratio of the gear changes with lateral steering deflections from the straight-ahead driving position, characterized in that the positive engagement between the intermediate gear member (14) and the coupling member (21) is designed and arranged in this way that the intersection of the line of action (JV) of the steering force transmitted at the point of engagement (20, 22 or 20, 23) with the plane containing the axis of rotation of the steering column shaft (12) and perpendicular to the linear direction of movement (F) of the intermediate gear member (L) has its greatest distance from the axis of rotation of the steering column shaft in the straight-ahead driving position of the transmission and, when steering deflections, approaches the axis of rotation of the steering column shaft immediately and quickly 2. Transmission according to claim 1, characterized in that the coupling member (21) has two guide slots for one of the intermediate gear member (14) laterally projecting pin (20) and that the two slots and Pin in the straight-ahead driving position of the transmission arranged symmetrically to the said plane (L) are. 3. Transmission according to claim 2, characterized in that the longitudinal center lines (y) of the slots (22 and 23) run radially to the axis of rotation of the steering column shaft (12). 4. Transmission according to claim 2 or 3, characterized in that the pivot angle of the coupling member (21) and the angle between the longitudinal center lines (y) of the slots are coordinated so that in each of the transmission end positions a slot center line in the said plane (L) falls. 5. Transmission according to claim 4, characterized in that the angle between the longitudinal center lines (y) is approximately 90 °. 6. Transmission according to one of the preceding claims with a steering worm and on this guided steering nut, characterized in that the worm is formed steeply in a manner known per se. Considered publications: German Auslegeschrift No. 1039 853,
016 135; German patents nos. 939 794, 936 552,
637, 701796, 105,475;
German utility model No. 1757 970;
French Patent No. 1153,946;
U.S. Patents Nos. 2,327,013, 2,143,858,
2012028, 1967 482. 1 sheet of drawings