WO2019101384A1

WO2019101384A1 - Drive transmission for a steering mechanism

Info

Publication number: WO2019101384A1
Application number: PCT/EP2018/074771
Authority: WO
Inventors: Steffen Schwarzer; Christoph Lauzansky
Original assignee: Robert Bosch Gmbh
Priority date: 2017-11-23
Filing date: 2018-09-13
Publication date: 2019-05-31
Also published as: DE102017220951A1

Abstract

The invention relates to a drive transmission comprising a first gear and a second gear, which cooperate to transmit a torque, wherein the torque is to be introduced via the first gear and transmitted by the second gear to a drive pinion (56) for a gear rack, wherein a longitudinal axis of the second gear defines an axial direction, wherein the second gear is mounted such that it can move in the axial direction, and wherein also at least one element (62) is provided for applying a pressing force to the second gear, which acts in the axial direction towards the first gear, and wherein the first gear and the second gear are arranged axially offset relative to one another.

Description

description

title

Transmission gear for a steering device

The invention relates to a transmission gear for a steering device and such a steering device, which is used in a motor vehicle.

State of the art

A steering device or steering is used in vehicles

Device that serves to influence the direction of travel of the vehicle.

Usually this is a by a driver via a steering wheel

applied hand torque transferred so that wheels of the vehicle are articulated according to the driver's request and in this way the vehicle is controlled.

In steering systems steering gear, which are also referred to as transmission gear, used. These are especially in the

Transmission range of rotary used on a translatory movement. Thus, transmission or steering gear can be used to transfer from a steering handle, eg. A steering wheel, applied hand torque and applied by a servo motor auxiliary torque on a rack of a rack and pinion steering.

Document EP 1 006 040 B1 describes such a steering device which serves to turn steerable wheels of a motor vehicle. This steering device comprises a manually rotatable input member, an output member, a

Torsionsstange connecting the input member and the output member, an electric motor and first and second intermeshing gears for

Transmitting a driving force of the electric motor to the output member. The First and second gears, which represent the transmission gear, are a spiroid or worm gear set.

Known transmission gears in steering use worm or Schraubradgetriebe as transmission gear for the power steering. However, these applications require when using the steering gear many compensation elements for springing to meet the function of the steering gear in terms of acoustics, feel and durability. It should be noted that these compensating elements cause further disruptive effects.

Disclosure of the invention

Against this background, a transmission gear according to claim 1 and a steering device with such a transmission gear according to claim 12 are presented. Embodiments emerge from the dependent ones

Claims and from the description.

The transmission described has a first gear and a second gear, which mesh and cooperate for transmitting a torque, the torque to be transmitted can be applied by a driver to a steering handle manual torque and / or a provided by a servo or auxiliary motor auxiliary torque his. This torque is introduced via the first gear, which may be formed as a worm, and transmitted to the second gear, which may be formed as a bevel gear. From this, in turn, the moment becomes a drive pinion for one

Transfer rack. The longitudinal axis or axis of rotation of the second gear or bevel gear and thus the drive pinion defines an axial

Direction. The second gear or bevel gear is mounted displaceably in the axial direction, wherein additionally at least one element for applying a contact pressure force is provided on the second gear or bevel gear, which acts in the axial direction towards the first gear. In addition, the first gear and the second gear are arranged offset in axial direction to each other. Axis offset means that the axis of the first gear, typically the axis of rotation of the first gear, is not aligned with an axis of the second gear. This will be explained in more detail below in connection with FIG.

In a bevel gear, the axes do not run parallel to each other, but intersect. The basic form of the bevel gear is a truncated cone whose outer surface is toothed. The teeth run regularly straight in the direction of the generatrices. In the case of the so-called hypoid wheel, however, they are curved. The so-called hypoid gear is a modification of the bevel gear. In this, the axes of drive and ring gear are offset, therefore do not intersect.

The transmission transmission described is in execution a kind of bevel gear. Bevel gear, which are also referred to as an angle gear, are used for transmitting rotational movements and torques. Such bevel gear generally include input and output shafts whose axes usually have a common point of intersection. The

Power transmission takes place in these by bevel gears. Is however a

Axis offset before, so this is referred to as hypoid gear. In the case of hypoid bevel gearboxes, the associated rolling and sliding movements promote higher gear ratios and thus better efficiencies.

In bevel gearboxes, for example, straight-toothed bevel gears,

Helical bevel gears or bevel gears are used. Curved bevel gears are, for example, bevel gears and Hypoidkegelräder.

The transmission transmission described is characterized by the fact that instead of a worm-gear mesh, a hypoid wheel can be combined with a worm. This has the consequence that a lateral, ie an axial rather than a radial engagement situation of the meshing wheels can be achieved. In addition, a misalignment shift made without correcting the teeth and thus installation space can be saved. Hypoid bevel gears are a form of spiral bevel gears. These are characterized by the fact that the pinion and crown gear axes do not converge in one point. This means that the pinion axis is offset from the wheel axis in height. This offset is referred to as offsetting.

Due to the axial offset, the pinion has a larger spiral angle than the ring gear. The resulting from the larger spiral angle larger

Forehead module causes an enlargement of the pitch circle diameter of the hypoid pinion. This results in a higher load capacity of a hypoid gearbox compared to a spiral bevel gear. Therefore, the decrease

Surface pressure on the teeth. By increasing the spiral angle of the pinion, the degree of overlap of the toothing is increased. Thus, with the same dimensions higher ratios than bevel or Schraubradverzahnungen can be realized.

In one embodiment, therefore, a worm-gear worm gear is provided with a hypoid gear as a bevel gear in combination with a Anfederungselement as an element for applying a contact force, which presses the hypoid wheel axially to the worm and in this way a

Catch realized. By this springing the meshing engagement is ensured even with wear of a tracking. Due to the pure axial movement, the Anfederungselement also acts directly on the movement and thus on the meshing engagement. Thus, a damping in the structure can be integrated in a simple manner.

The presented steering device has at least one transmission gear described above and is used in particular in a motor vehicle. In this case, a transmission gear for transmitting a

Hand torque, which is applied to a steering handle, and / or a transmission gear for transmitting a servo torque, which is provided by a servo motor may be provided.

The presented transmission gear has, at least in some of

Designs, a number of advantages. In particular, no use of additional compensation elements is required. So that's possible here presented Anfederungskonzepte a simpler design compared to known compensation elements. Furthermore, there are less emitted disturbances. The modified design also allows a wider range of applications. It should also be noted that instead of pivoting a pure axial movement is performed.

It has to be taken into account that the concept of springing allows the teeth to be better kept together. There is thus no additional compensation of the Anfederungselements required. Furthermore, due to the axial springing, a linear movement takes place instead of a pivoting movement, which in turn results in more accurate tolerances.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

Brief description of the drawings

Figure 1 shows a steering device according to the prior art.

FIG. 2 shows a detail from FIG. 1.

Figure 3 shows an embodiment of the proposed transmission gear.

FIG. 4 shows another embodiment of the transmission gear described. FIG. 5 shows a further embodiment of the transmission gear.

Embodiments of the invention The invention is schematically illustrated by means of embodiments in the drawings and will be described in detail below with reference to the drawings.

Figure 1 shows a known steering device, which is generally designated by the reference numeral 10. The illustration shows a rack 12, a steering shaft 14 leading to a steering handle (not shown), a servomotor 16, and a transmission gear 18. This transmission gear 18 transmits the assist torque provided by the servomotor 16 to the rack 12

Transmission gear 18 transmits a rotational movement, which in turn is translated into a translational movement of the rack 12.

The transmission gear shown in Figure 1 18 is shown enlarged in Figure 2. The illustration shows a worm 30, via which the moment of the servomotor is initiated. The worm 30 cooperates with a bevel gear 32, which in turn typically translates the rack via a drive pinion.

The above-described operation is also in the

Transmission gear, as presented herein, given. This mode of operation is referred to in the transmission transmission presented.

The transmission gear 18 of Figure 2 has two compensating elements 34 which serve as springing and on the worm 30 and thus on the element which introduces the force applied by the servo motor or the applied torque in the transmission gear 18, attack. However, this springing has the disadvantages mentioned above.

Figure 3 shows an embodiment of the proposed transmission gear, which is designated overall by the reference numeral 50. This transmission gear 50 can basically be used in a steering device 10, as shown in FIG. The illustration shows a worm 52 which is provided with a bevel gear 54

interacts. The worm 52 is thus an embodiment of a gear and represents the element or the component, via which a moment, for example. By a servo motor or a steering handle, applied in the

Transmission gear 50 is introduced or introduced. The bevel gear 54, which cooperates with the worm 52, is connected to a drive pinion 56 whose rotary motion in turn is a rack (not shown).

driving translationally. This rack causes by their translational movement pivoting of the hinged wheels. The drive pinion 56 is mounted in a housing 58 by means of two bearings 60. These bearings 60 are typically designed as ball bearings.

The illustration also shows an element 62 for applying a

Contact force acting on the bevel gear 54. This is movably mounted in the axial direction, in particular, the bevel gear 54, which may be formed as a hypoid wheel, on a sliding seat, which may be given by the two bearings 60, stored. The element 62 for applying a contact pressure comprises a first spring 64, which is associated with a first damper member 66, and a second spring 68, which is associated with a second damping member 70. In principle, the element 62 for applying a contact pressure force can have a spring element to which an attenuation element is assigned. The spring element acts on the path of the bevel gear 54, the

Damper acts on the speed of the bevel gear 54. Significantly, the element 62 acts to apply a contact force on the bevel gear 54 and not on the worm 52.

Figure 4 shows a further embodiment of the transmission gear, which is generally designated by the reference numeral 100. The illustration shows a first gear 102, which is formed in this case as a worm, and a second gear 104, which is designed here as a bevel gear. This second gear 104 may be formed as a spiroid, hypoid, globoid, conical or crown wheel. The two gears 102, 104 cooperate, so that an initiated by the first gear 102 torque is transmitted to the second gear 104. The illustration also shows a bearing 106 for an output shaft 108, which is fixedly connected to the second gear 104 and derives the torque transmitted to this second gear 104. Furthermore, a toothing 110 of the second gear 104, springs 112, attenuators 114 and a rack 116 of a steering device can be seen, wherein the rack 116 cooperates with a transmission member 118 of the output shaft 108.

The teeth 110 may be arcuate, oblique or straight toothed. An arcuate toothing is provided, for example, in a hypoid wheel. A hypoid wheel as a second gear 104 also allows the use of an axially parallel screw as the first gear 102. For the springs 112, which serve as springing, it should be noted that the following applies:

F = c * s, where F is the force, c the spring constant and s the spring travel, which is also illustrated here with a double arrow 120.

The attenuators 114 are here and act parallel to the springs 112. Springs 112 and attenuators 114 may be formed as separate components but also as a combined component. Thus, for example, a layer of an elastomeric material can be used, which has both resilient and damping properties. The spring acts on the way, the attenuator on the speed.

Furthermore, a rotation axis 130 of the first gear 102 and an axis of rotation 132 of the second gear 104 is shown. Perpendicular to the axis of rotation 132 of the second gear 104 is a longitudinal axis 134 of the second gear 104. It can be seen that the axis of rotation 130 of the first gear does not intersect this longitudinal axis 134 is not in alignment with this, but is offset to this, as with a double arrow 136 is illustrated. The two gears 102 and 104 are thus arranged offset in axial direction to each other.

Reference numeral 140 denotes a displacement possibility, for example, a

Sliding seat. FIG. 5 shows yet another embodiment of the transmission, which is designated overall by the reference numeral 200. The illustration shows a first gear 202, which is formed in this case as a worm, and a second gear 204, which here, for example, as a crown wheel, spiroid or hypoid wheel is formed as. The two gears 202, 204 cooperate, so that an initiated by the first gear 202 torque is transmitted to the second gear 204.

The illustration also shows a bearing 206 for an output shaft 208, which is fixedly connected to the second gear 204 and the second

Gear 204 derived torque derived. Furthermore, a toothing 210 of the second gear 204, springs 212, attenuators 214 and a rack 216 of a steering device can be seen, wherein the rack 216 with a transmission member 218 of the output shaft 208 cooperates.

Also in this illustration, the off-axis positioning of the two gears 202 and 204 can be seen. For the components essentially applies to what has already been explained in connection with Figure 4. Reference numeral 240 denotes a displacement possibility, for example a sliding seat.

Claims

claims

Transmission gear with a first gear (102, 202) and a second gear (104, 204), which cooperate to transmit a moment, wherein the moment on the first gear (102, 202) is initiated and by the second gear (104 , 204) is to be transmitted to a drive pinion (56) for a rack (116, 216), wherein a longitudinal axis of the second gear (104, 204) defines an axial direction, wherein the second gear (104, 204) displaceable in the axial direction is mounted, and wherein additionally at least one element (62) for applying a contact force to the second gear (104, 204) is provided, which in the axial direction towards the first gear (102,

202), and wherein the first gear (102, 202) and the second gear (104, 204) are arranged offset in relation to each other.

2. transmission transmission according to claim 1, wherein the first gear (102, 202) as a screw (52) is formed.

3. transmission transmission according to claim 1 or 2, wherein the at least one element (62) is a spring (64, 68, 112, 212).

4. transmission transmission according to claim 1 or 2, wherein the at least one element (62) is a body made of an elastomeric material.

5. transmission transmission according to one of claims 1 to 4, wherein the element (62) is associated with an attenuator (66, 70, 114, 214).

6. transmission transmission according to one of claims 1 to 5, wherein the second gear (104, 204) as a bevel gear (54) is formed.

7. Transmission gear according to one of claims 1 to 5, wherein the second gear (104, 204) is designed as a hypoid wheel.

8. Transmission gear according to one of claims 1 to 5, wherein the second gear (104, 204) is designed as a crown wheel.

9. transmission transmission according to one of claims 1 to 8, wherein a

Housing (58) is provided, in which the transmission gear (50, 100, 200) is received at least in sections.

10. transmission transmission according to claim 9, comprising the drive pinion (56) for a rack (116, 216), wherein the second gear (104, 204) with the

Drive pinion (56) is connected and the Antriebstitzei (56) is mounted with at least one bearing in the housing (58).

11. transmission transmission according to claim 10, wherein the at least one bearing (60, 106, 206) is designed as a ball bearing.

12. Steering device with at least one transmission gear (50, 100, 200) according to one of claims 1 to 11.