GB2246989A

GB2246989A - Motor vehicle gearbox construction with low structure-borne noise.

Info

Publication number: GB2246989A
Application number: GB9117227A
Authority: GB
Inventors: Karl Pichler; Josef Deutsch
Original assignee: Steyr Daimler Puch AG
Current assignee: Steyr Daimler Puch AG
Priority date: 1990-08-10
Filing date: 1991-08-09
Publication date: 1992-02-19
Anticipated expiration: 2011-08-09
Also published as: FR2665673B3; GB9117227D0; DE4025448A1; FR2665673A3; GB2246989B; DE4025448C2

Abstract

A gearbox housing (1) has a gearbox cover (2) (or turret, Fig. 2) in which a gear lever (3) is pivotably mounted. In order to prevent the emission of structure-borne noise, the gearbox cover (2) has bores (10) which receive damping members each comprising a resilient ring (12) and an internal metallic bush (13). Screws (14) clamp only the metallic bush (13), without touching the gearbox cover (2). <IMAGE>

Description

1 "Motor-vehicle transmission having a gearshift device with low

structure- borne noise,, This invention relates to a motor-vehicle transmission, comprising a gearbox housing having a gearbox cover and/or turret, in which a gear lever is pivotably mounted, the gearbox cover and/or turret being secured to the gearbox housing by means of screws.

Considerable demands are made upon motor-vehicle transmissions, including a low level of noise, both with respect to the transmission of sound to the outside, in order to reduce traffic noise, and with respect to the transmission of sound into the interior., in order to increase travelling comfort. Although careful design and machining of rotating parts in the interior of the transmission is required in any case, the transmission of sound to the outside is reduced by appropriate shaping and sound-proofing of the gearbox housing. These steps and the application of damping material in the floor of the passenger compartment also reduce the nuisance caused by noise in the interior of the vehicle.

The transmission of sound through parts of the transmission projecting into the passenger compartment, 2 e.g. via the gearbox cover or turret and the gear lever, remains annoying. The sound waves are transmitted via the gearbox cover and/or turret and into the gear lever by means of the metallic connection thereof to the gearbox housing. These parts then emit sound waves in.a relatively high frequency range in the interior of the vehicle. In describing this frequency range it should be noted that a gearbox turret has substantially the same size and shape as a handbell and a gear lever has substantially the same dimensions as an elongated musical triangle, and the resulting sounds transmitted are particularly annoying.

This problem arises in all transmissions from which a gear lever projects directly into the passenger compartment, and in particular in distributor gearboxes of cross-country cars.

An object of the invention is to prevent these noise emissions from the gearbox cover and/or gearbox turret in the audible frequency range with little technical outlay.

The invention provides a motor-vehicle transmissionas claimed in claim 1.

This prevents the introduction of structure-borne noise

1 1 3 from the gearbox housing into the gearbox cover or turret in a surprisingly simple manner. It has surprisingly been found that this step is not only highly effective, but also that the strength of the connection is not adversely affected, provided that the bushes are dimensioned in such a way that they withstand the tightening force of the screws.

In a preferred embodiment of the invention either each resilient ring or each bore in the gearbox cover or the turrets has a bead engaging in a corresponding recess in the other part, respectively. A resilient ring constructed in this way can be "inserted" in a simple manner during assembly and then transmits higher holding-down forces.

If the gearbox cover or turret has a positioning flange which engages in an appropriately shaped opening in the housing, it is advantageous to insert a damping member, or, particularly in the case of a circular recess, an 0-ring, between the positioning flange and the housing. This ensures that no metallic contact at all occurs between the gearbox housing and the gearbox cover or the turret.

Preferably a resilient member is arranged between the gearbox lever and the pivot bearing thereof. This 4 4 ensures that even in the path via the gearbox forks, the gearbox rods, the gearbox fingers and the pivot bearing no structure-borne noise is transmitted to the gearbox cover or turret.

A particularly simple and effective design is provided in the case of gearboxes in which the gear lever is pivotable only about one pin, for example in the case of distributor gearboxes, by arranging a resilient sleeve between the gear lever and the pivot pin.

In a further embodiment of the invention the gear lever is mounted on the resilient sleeve by means of two spaced resilient rings. In this way the contact area between the gear lever and the pivot pin is still smaller and it is possible to arrange these rings on the pivot pin at places where there is no amplitude maximum when a standing wave is formed in the pivot pin.

Finally, it is also advantageous to provide that the gearchange finger acts by way of a resilient member upon the gearchange members arranged downstream.

Two embodiments of the invention will now be described with reference to the accompanying drawings, wherein:

Fig. 1 is a vertical section through a first embodiment 1 of the invention, Fig. 2 is a vertical section through a second embodiment of the invention, and Fig. 3 shows the detail A of Fig. 1 enlarged.

Fig. 1 shows the upper part of a motor-vehicle gearbox of which only the gearbox housing 1 is shown in part, a gearbox cover 2 being secured to the gearbox housing 1. A gear lever 3 is pivotably mounted in the gearbox cover 2. A gaiter 5 is mounted between the gear lever 3 and the cover 2, and the gear lever knob 4 is situated at the upper end of the gear lever 3.

In this example the gearbox cover 2 is circular in outline and is provided with a positioning flange 6, which engages with an engaging surface 8 of the housing 1. A circular 0-ring 7 is inserted between the flange 6 and the engaging surfaces 8, in order to damp or prevent the metallic contact between the two surfaces.

A plurality of bores 10, of which only one is shown in Fig. 1, are provided in the cover 2 for securing it to the housing 1. This bore 10 is provided about half-way up with an annular bead 11 with which a resilient ring 12 engages by means of a corresponding groove 111. The 6 bead 11 and the groove 111 could equally well be transposed. A bush 13 of metal, which is pressed by the head 15 of the screw 14 against the housing 1, is securely joined to the resilient ring 12, for example by vulcanization. In this way the cover 2 is not directly in contact with the gearbox housing 1 at any point, so that no structure-borne noise can be transmitted to the cover 2.

A preferably cylindrical pivot bearing cup 16, in the upper part of which are arranged two bores 17 for receiving a pivot pin 18, is formed in the cover 2. The base 19 of the cup 16 is open.

The gear lever 3 comprises a gear lever ball 20 which continues downwards by way of a gear lever finger 21 into a ball head 22 which engages in gearchange slideways or other gearchange members (not shown) with the interposition of a member 23 of plastics material. Above the gear lever ball 20 the gear lever 3 is hollow and is formed as a tube 24 as far as its upper end, the inner cavity 25 of the tube 24 being filled with a damping substance, for example sponge rubber or plastics foam. The gear lever knob 4 is securely joined to the gear lever 3.

A bearing disc 27 is urged from below against the gear 7 lever ball 20 under the action of a spring 26, the spring 26 being supported on the base 19 of the pivot bearing cup 16. In the embodiment illustrated, the gear lever ball 20 is pivotable in only one direction, but it could also be mounted so as to be pivotable in two directions by omitting the pin 18.

Fig. 2 differs from Fig. 1 only in that the gearbox cover 42, which is screwed to the gearbox housing 41 by means of screws either in a conventional manner or according to the invention, carries a gear lever turret 45 which is connected to the cover 42 by means of screws and resilient rings 44 as described for Fig. 1. Thi s also naturally necessitates a longer gearchange finger 46. It would also be possible to attach the turret 45 directly to the gearbox housing 41.

A possibility of mounting the gear lever 3 on the pivot pin 18 is shown more precisely in Fig. 3. To this end the gear lever ball 20 is provided in the transverse direction with a bore 30 with two peripheral grooves 31 which are arranged at a specific distance from each other. Resilient rings 32 of a suitably selected plastics material inserted into the grooves 31 embrace a resilient sleeve 33 also formed of plastics material and surrounding the pivot pin 18. In this case the rings 32 are dimensioned in such a way that the sleeve 33 does 8 not touch the bore 30 of the gear lever ball 20, and either the rings 32 slide on the sleeve 33 or the sleeve 33 slides on the pivot pin 18. In this way, and with a suitably selected distance between the two rings 32, transmission of structure-borne noise between the pivot pin 18 and the gear lever 3 does not take place at all.

'I 1 9

Claims

Claims:

1. A motor-vehicle transmission, comprising a gearbox housing having a gearbox cover and/or turret in which a gear lever is pivotably mounted, the gearbox cover and/or turret being secured to the gearbox housing by means of screws, wherein the gearbox cover and/or turret has a plurality of bores for receiving the screws, the bores receiving damping members each comprising a resilient ring and an internal metallic bush, the screws clamping the metallic bush onto the housing or cover, without touching the gearbox cover or turret thereby preventing the transmission of noise from the gearbox to the cover on the turret..

2. A motor-vehicle transmission as claimed in Claim 1, wherein the resilient ring of each damping member or the associa.e-' bore has a bead engaging in an annular groove in the bore or in the resilient ring, respectively.

3. A motor-vehicle transmission as claimed in Claim 1, wherein the gearbox cover, the gearbox turret or the gearbox housing has a positioning flange, and a damping member is inserted between the positioning flange and the gearbox housing, the gearbox cover, or the turret, respectively.

4.

4. A motor-vehicle transmission as claimed in Claim 3, wherein the damping member is an 0-ring.

5. A motor-vehicle transmission as claimed in Claim 4, wherein a resilient member is arranged between the gear lever and a pivot bearing thereof.

6. A motor-vehicle transmission as claimed in Claim 5, wherein the gear lever has a single pivot pin, and the resilient member is a sleeve arranged between the pivot pin and the gear lever.

7. A motor-vehicle transmission as claimed in Claim 6, wherein the gear lever is mounted on the resilient sleeve by means of two spaced resilient rings.

8. A motor-vehicle transmission as claimed in Claim 6, wherein the gear lever is provided at the bottom with a gearshift finger surrounded by a resilient member.

9. A motor vehicle transmission substantially as herein described with reference to Figs. 1 and 3 or Figs. 2 and 3 of the accompanying drawings.

Sales Branch- Unit 6 Published 1992 at The Patent Office. Concept House. Cardiff Road. Newport. Gwem NP9 IRH Further copies may be obtained fron Nine Mile Point. C-A- mfelinfach. Cross Keys. Newport. NPI 7HZ. Printed b%,Multiplex techniques lid. St Man- Cray - Kem 1