DE102007034816B4 - Decoupling element and steering gear subframe arrangement with such - Google Patents

Abstract

Decoupling element (1) for axial insertion into an opening (11), comprising:
- A metallic bushing (2) which has a through opening (3) running in the longitudinal direction and a radially widened head (4) at one axial end, and
- An elastomer body (6) attached to the outer circumference of the socket (2) and extending around the socket (2), characterized in that the metallic socket (2) has a non-rotationally symmetrical outer circumferential profile, the metallic socket (2) its head (4) forms an axial wall section (7), the elastomer body (6) extends over the axial wall section (7) of the head (4), and the elastomer body (6) under the head (4) of the bushing (2) has a constriction (9).

Description

The invention relates to a decoupling element according to the preamble of claim 1. Furthermore, the invention relates to an arrangement of a steering gear and an auxiliary frame, in which the steering gear is attached to the subframe via one or more decoupling elements.

If a steering system is connected to the subframe via rigid coupling elements, acoustically perceptible vibrations in the form of structure-borne noise can be transmitted to the subframe.

For acoustic decoupling, see DE 44 14 020 C1 a decoupling element with the features of the preamble of claim 1 is proposed. The known decoupling element has a metallic socket with a conical head. The bushing is coated with an elastomer material which is intended to serve as a damping body. The decoupling element is installed vertically. The damping body has a greater wall thickness in the longitudinal direction of the vehicle than in the transverse direction of the vehicle. This is intended to achieve high rigidity in the longitudinal direction of the vehicle and in the transverse direction of the vehicle and a high degree of softness in the transverse direction of the vehicle.

Further decoupling elements are in US 2006/0 278 030 A1 , U.S. 2,221,884 A and GB 1 228 282 A described.

The invention aims to provide alternatives for the acoustic decoupling of a steering gear from a subframe of a motor vehicle.

This object is achieved by a decoupling element according to patent claim 1.

With such a decoupling element, the transmission of structure-borne noise to the subframe is significantly reduced. Direction-optimized characteristics with regard to elasticity and damping behavior can be set on the elastomer body, so that good decoupling is achieved even in confined spaces.

The non-circular profile shape also allows space-saving adaptation to tight installation situations.

In particular, different stiffnesses in the axial direction and different radial directions can be achieved with little space requirement.

Advantageous embodiments of the invention are the subject of further claims.

The decoupling element is preferably used in an arrangement comprising a steering gear and an auxiliary frame according to patent claim 15.

According to an advantageous embodiment, the steering gear has a non-rotationally symmetrical opening into which the decoupling element is fitted. This is advantageous in terms of installation. In principle, however, it is also possible to support the decoupling element with its elastomer body in a suitable opening on the subframe and to connect the steering gear to the metallic socket of the decoupling element.

With regard to the ground clearance of the vehicle and adjacent components of the wheel suspension, it is advantageous if the opening for receiving the decoupling element in the installed position has a greater width in the horizontal direction than in the vertical direction.

In the case of a through opening on the steering gear, two decoupling elements can be inserted into the opening from opposite sides, the insertion of each decoupling element being axially limited by the axial wall section of the head covered with the elastomer body. This ensures acoustic decoupling both in the longitudinal direction of the socket and in different radial directions of the socket.

• 1 eine Längsschnittansicht durch ein Entkopplungselement nach einem Ausführungsbeispiel der Erfindung,
• 2 eine weitere Längsschnittansicht durch das Entkopplungselement in einer in gegenüber der Ansicht nach 1 um 90° angewinkelten Schnittebene,
• 3 eine Querschnittsansicht entlang der Linie III-III in 1,
• 4 eine Ansicht auf den Kopf des Entkopplungselements,
• 5 eine Darstellung einer Einbaulage von zwei Entkopplungselementen in einer Öffnung eines Lenkgetriebes, wobei die Längsachse der Entkopplungselemente quer zur Zahnstangenachse der Lenkung verläuft,
• 6 eine weitere Darstellung der Einbaulage an einem Lenkgetriebe in Richtung der Längsachse eines Entkopplungselements,
• 7 eine exemplarische Darstellung der statischen Federkennlinie des Entkopplungselements für zwei unterschiedliche Radialrichtungen, und in
• 8 eine exemplarische Darstellung der statischen Federkennlinie des Entkopplungselements in Axialrichtung.

The invention is explained in more detail below with reference to an exemplary embodiment shown in the drawing. The drawing shows in:

• 1 a longitudinal sectional view through a decoupling element according to an embodiment of the invention,
• 2 a further longitudinal sectional view through the decoupling element in an opposite to the view according to 1 cutting plane angled by 90 °,
• 3 a cross-sectional view along the line III-III in FIG 1 ,
• 4th a view of the head of the decoupling element,
• 5 a representation of an installation position of two decoupling elements in an opening of a steering gear, the longitudinal axis of the decoupling elements running transversely to the rack axis of the steering,
• 6th a further illustration of the installation position on a steering gear in the direction of the longitudinal axis of a decoupling element,
• 7th an exemplary representation of the static spring characteristic of the decoupling element for two different radial directions, and in
• 8th an exemplary representation of the static spring characteristic of the decoupling element in the axial direction.

That in the 1 to 4th The illustrated embodiment shows a decoupling element 1 , via which a steering gear of an electromechanical steering system can be attached to a subframe of a motor vehicle and at the same time acoustically decoupled.

Of course, the steering gear can have decoupling elements 1 can also be coupled to other sections of a vehicle body. In addition, the decoupling element explained below 1 can also be used to define other vibration-critical devices in order to decouple them acoustically or in a different frequency range at the same time.

The decoupling element 1 has a metallic socket 2 with a non-rotationally symmetrical outer circumference profile. In the illustrated embodiment, the socket 2 an oval outer circumferential profile that runs the length of the socket 2 is constant. However, other, edge-free profile shapes are also possible.

Due to the oval shape, which is particularly suitable for installation situations with dimensions restricted in one direction, the ratio of the largest width lies in the exemplary embodiment Dmax the socket 2 to the smallest width Dmin the socket 2 in the range from 1.1 to 1.4, preferably in the range from 1.15 to 1.3.

Furthermore, the socket 2 one lengthways A. running through opening 3 on. Also at one axial end is a radially widened head 4th educated. The head too 4th has a non-rotationally symmetrical, preferably oval outer circumference 5 on.

On the outer circumference of the socket 2 is an elastomer body 6th attached, for example vulcanized. The elastomer body 6th extends around the socket 2 around as well as over one of the end of the socket 2 facing away, axial wall section 7th of the head 4th . About the elastomer body 6th a decoupling is thus achieved both in the axial direction and in the radial direction.

In the illustrated embodiment, the elastomer body extends 6th ring-like only around an axial section of the bush near the head 2 . However, it is also possible to use the entire socket 2 with an elastomer body 6th to envelop. The elastomer body 6th , as in 3 shown, also have an oval outer peripheral profile.

In addition, the elastomer body can 6th also over the outer circumference 5 of the head 4th extend.

With regard to the coordination of the decoupling element 1 The wall thickness of the elastomer body usually differs in different radial directions 6th towards the largest width of the socket 2 from the wall thickness towards the smallest width of the socket 2 . The wall thickness can be varied as required.

In the 5 and 6th shown installation situation on a steering gear, it is advantageous that the elastomer body 6th towards the greatest expanse Dmax the socket 2 a greater wall thickness d ₁ and in the direction of the smallest width Dmin the socket 2 a smaller wall thickness d ₂ having.

The wall thickness ratio is preferably between the smallest radial wall thickness d ₂ and the greatest radial wall thickness d ₁ on the elastomer body 6th ranges from 1: 1.1 to 1: 1.8.

The ratio of the wall thickness of the elastomer body 6th the diameter of the outer wall of the socket 2 towards the smallest width of the socket 2 is in the range of d ₂ / D _min = 0.15 to 0.45, preferably in the range of d ₂ / D _min = 0.25 to 0.4.

The ratio of the wall thickness of the elastomer body 6th to the diameter of the outer wall of the socket in the direction of the largest width of the socket 2 is in the range of d ₁ D _max = 0.25 to 0.5, preferably in the range of d ₁ D _max = 0.3 to 0.45.

To facilitate the introduction of the decoupling element 6th the elastomer body can be inserted into an opening 6th A taper on the insertion side 8th exhibit. Further is under the head 4th the socket 2 on the elastomer body 6th a constriction 9 educated.

5 and 6th show the installation situation of decoupling elements 1 on an arrangement of a steering gear 10 and a not shown, but known subframe. The decoupling elements 1 serve here both for fastening and for acoustic decoupling of the electromechanical steering.

The steering gear 10 a through opening 11 on whose longitudinal axis B. essentially horizontally and transversely to a rack axis C. runs. 6th shows the steering gear 10 and a decoupling element 1 with respect to the orthogonal vehicle coordinates x, y and z, where x represents the vehicle longitudinal direction, y the vehicle transverse direction and z the vehicle vertical direction.

The passage opening 11 has one of the non-rotationally symmetrical shape of the elastomer body 6th corresponding cross-sectional shape, which is oval in the illustrated embodiment. Thus results at the opening 11 in the installation position, a greater width in the transverse direction of the vehicle than in the vertical direction or vertical direction of the vehicle. The dimensions of the through opening 11 are so on the elastomer body 6th matched that this is hardly or only slightly compressed radially.

In the illustrated embodiment are in the through opening 11 two decoupling elements 1 introduced from opposite sides. Here is the insertion of each decoupling element 1 axially through the with the elastomer body 6th coated axial wall section 7th of the head 4th limited.

The coordination of the decoupling element explained above 1 is in the 7th and 8th shown on the basis of static spring characteristics. 7th shows the course of the static characteristic c _y in the transverse direction of the vehicle and the characteristic curve c _z in the vertical direction of the vehicle. Both characteristics show a similar course here. However, it is also possible to provide a different characteristic curve depending on requirements.

In 8th is the static spring characteristic c _x shown in the vehicle longitudinal direction or axial direction. The specified characteristic values show that the decoupling element 1 has a greater elasticity in the axial direction than in the radial direction. Depending on the installation situation, the elasticity can be adjusted variably in the axial and radial direction. For example, the elasticity in the axial direction can also be smaller than in the radial direction. In particular, a reversal of the relationships over the course of the characteristic curve is also conceivable.

By tuning the elastomer body 6th In the x, y, z direction, different bearing forces resulting from the rack forces introduced by the tie rods can be optimally absorbed and the acoustic performance and the driving dynamics of the steering can be improved.

The oval shape of the decoupling elements 1 allows the axis B. the passage opening 11 as close as possible to the rack axis C. to be arranged, whereby an improved clearance to chassis components is achieved. How in particular 5 shows can by restricting the arrangement of the elastomeric body 6th on sections of the socket close to the head 2 an additional gain in space in the overlapping area of the axes B. and C. be achieved. The passage opening 11 is here by two axially spaced bearing eyes 12th educated.

List of reference symbols

1

Decoupling element

2

metallic socket

3

Through opening of the socket

4th

head

5

Outer circumference of the head

6th

Elastomer body

7th

axial wall section of the head

8th

rejuvenation

9

Constriction

10

Steering gear

11

Passage opening on the steering gear

12

Bearing eye

A.

Longitudinal axis of the socket or the through opening 3

B.

Longitudinal axis of the through opening 11

C.

Rack axis

c _x

static spring stiffness in the longitudinal direction of the vehicle

c _y

static spring stiffness in the transverse direction of the vehicle

c _z

static spring stiffness in the vertical direction of the vehicle

d ₁

large wall thickness of the elastomer body

d ₂

small wall thickness of the elastomer body

Dmax

maximum width or maximum diameter of the socket

Dmin

minimum width or minimum diameter of the socket

Claims (18)

Decoupling element (1) for axial insertion into an opening (11), comprising: - a metallic bush (2) which has a through opening (3) running in the longitudinal direction and a radially widened head (4) at one axial end, and - an elastomer body (6) attached to the outer circumference of the bushing (2) and extending around the bushing (2), characterized in that the metallic bushing (2) has a non-rotationally symmetrical outer circumferential profile, the metallic bushing (2) on its Head (4) forms an axial wall section (7), the elastomer body (6) extends over the axial wall section (7) of the head (4), and the elastomer body (6) under the head (4) of the bushing (2) Has constriction (9). Decoupling element after Claim 1 , characterized in that the socket (2) has an oval outer circumferential profile. Decoupling element after Claim 1 or 2 , characterized in that the elastomer body (6) has an oval outer circumferential profile. Decoupling element according to one of the Claims 1 to 3 , characterized in that the head (4) has a non-rotationally symmetrical, preferably oval outer circumference. Decoupling element according to one of the Claims 1 to 4th , characterized in that the elastomer body (6) extends ring-like around an axial section of the bushing (2) close to the head. Decoupling element according to one of the Claims 1 to 5 , characterized in that the elastomer body (6) extends over the outer circumference of the head (4). Decoupling element according to one of the Claims 1 to 6th , characterized in that the elastomer body (6) extends ring-like around the bush (2), the wall thickness of the elastomer body (6) in the direction of the largest width of the bush (2) from the wall thickness in the direction of the smallest width of the bush ( 2) differs. Decoupling element according to one of the Claims 1 to 7th , characterized in that the elastomer body (6) has a greater wall thickness in the direction of the largest width of the bushing (2) and a smaller wall thickness in the direction of the smallest width of the bushing. Decoupling element according to one of the Claims 1 to 8th , characterized in that the wall thickness ratio between the smallest and largest radial wall thickness on the elastomer body (6) is in the range from 1: 1.1 to 1: 1.8. Decoupling element according to one of the Claims 1 to 9 , characterized in that the ratio of the wall thickness of the elastomer body (6) to the diameter of the outer wall of the bushing (2) in the direction of the smallest width of the bushing is in the range from 0.15 to 0.45, preferably 0.25 to 0.4 . Decoupling element according to one of the Claims 1 to 10 , characterized in that the ratio of the wall thickness of the elastomer body (6) to the diameter of the outer wall of the socket (2) in the direction of the largest width of the socket is in the range from 0.25 to 0.5, preferably 0.3 to 0.45 . Decoupling element according to one of the Claims 1 to 11 , characterized in that the ratio of the largest width of the bush (2) to the smallest width of the bush (2) is in the range from 1.1 to 1.4, preferably 1.15 to 1.3. Decoupling element according to one of the Claims 1 to 12th , characterized in that the decoupling element (1) has a greater elasticity in the axial direction than in the radial direction. Decoupling element according to one of the Claims 1 to 12th , characterized in that the decoupling element (1) has a smaller elasticity in the axial direction than in the radial direction. Arrangement of a steering gear (10) and an auxiliary frame, characterized in that the steering gear is fastened to the auxiliary frame via one or more decoupling elements (1) according to one of the preceding claims. Arrangement according to Claim 15 , characterized in that the steering gear housing (10) has a non-rotationally symmetrical opening (11) into which the decoupling element (1) is fitted. Arrangement according to Claim 16 , characterized in that the opening (11) in the installed position has a greater width in the horizontal direction than in the vertical direction. Arrangement according to one of the Claims 15 to 17th , characterized in that two decoupling elements (1) are inserted from opposite sides into an opening (11) on the steering gear (10), the insertion of each decoupling element (1) axially through the axial wall section (7) coated with the elastomer body (6) ) of the head (4) is limited.

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