GB2362196A

GB2362196A - Device for operating an automated shift transmission

Info

Publication number: GB2362196A
Application number: GB0119482A
Authority: GB
Inventors: Andreas Rogg
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1997-05-30
Filing date: 1998-05-27
Publication date: 2001-11-14
Anticipated expiration: 2018-05-27
Also published as: GB0119482D0; GB2362196B

Abstract

A device for operating an automated shift transmission contains a gearbox housing 8, an electric motor set in a motor housing 2, and an intermediate gear 4 driven by the electric motor. The output member 6 of the intermediate gear is connected to an operating member 48 of the automated shift transmission. The intermediate gear is housed in an intermediate housing 20 which is connected to the motor housing 2 and the gearbox housing 8. The inside of the intermediate housing is sealed oil-tight from the inside of the gearbox housing. A device 18, preferably a compression spring, is provided to give elasticity in the drive from the gear 4.

Description

2362196 DEVICE FOR OPERATING AN AUTOMATED SHIFT TRANSMISSION The invention

relates to a device for operating an automated shift transmission, containing a gearbox housing, an electric motor set in a motor housing, an intermediate gearbox driven by the electric motor with its output member connected to an operating member of the automated shift transmission.

Automating shift transmissions has become increasingly important in recent times. Automated shift transmissions of this kind are more cost- effective than conventional automatic gearboxes operated with planetary gears or automatic belt contact gearboxes and operate with an is improved degree of efficiency which allows fuel savings to be made. Advances have meanwhile been made in the field of electronic controls and actuator systems so that automating conventional shift transmissions provides the best possibility of on the one hand improving the operating comfort of motor vehicles and on the other hand of reducing their fuel consumption. Automated shift transmissions of this kind are known for example from DE 19627980.

As actuators, i.e. drives for the automatic operation of a conventional shift transmission of this kind whose operating member is mostly formed as a shift/selector shaft, are frequently used electric motors in conjunction with mechanical transfer members since these can be controlled particularly easily, do not require a lot of space, are cost- effective and except for their cabling require no additional expense in the vehicle such as for example hydraulic drives. Electric motor drives of this kind have to be sealed against the penetration of dirt and water. In addition a seal against gearbox oil is required at at least one point in the transfer path between the electric motor and operating member since otherwise there is the danger that in particular oil vapours might be ignited through sparks. Furthermore the sensors frequently integrated directly into the electric motor actuators for path measurement are generally not oilresistant.

The object of the invention is therefore to provide a device of the generic kind whereby the electric motor is reliably protected from the oil which normally exists inside the gearbox housing or against dirt and /or water from outside, and whereby the gearbox is protected from dirt and/or water.

According to the invention there is provided a device for operating an automated shift transmission containing a gearbox housing, a motor housing, an electric motor in the motor housing, an intermediate gearing driven by the electric motor and whose output member is connected to an operating member of the automated shift transmission, wherein the intermediate gearing is housed in an intermediate housing which is connected to the motor housing and the gearbox housing, the inside of the intermediate housing is sealed oil-tight from the inside of the gearbox housing, and a device is provided in the intermediate housing to produce a predetermined elasticity between the output shaft of the electric motor and the operating member of the shift transmission.

The sealed tightness is provided by means of a seal. This seal is in an advantageous embodiment single seals are used to seal, respectively, the intermediate gear housings from the inside of the gearbox housing and the motor housings from the inside of the gearbox housing. An advantageous design can be reached if the intermediate gear and the inside of the electric motor housing are sealed by one seal wherein otherwise two seals would be required, one for the electric motor and one for the intermediate gear. A further seal of the inside of the intermediate housing and/or of the engine housing can be produced relative to the outside area by means of one seal. Furthermore a seal is provided in the area of the fixing between the electric motor housing and the intermediate gearbox housing in order to seal the electric motor housing from the exterior whereby this seal is advantageously formed as an 0-ring seal.

The inside of the intermediate gearbox offers a buffer space between the inside of the gearbox housing and where applicable a secondary housing, which is normally is connected to the inside of the gearbox housing and holds devices for operating the operating member of the gearbox. By means of the intermediate housing a distance is provided between the oil-filled shift transmission and the electric motor. The operating reliability is particularly improved because the inside of the intermediate housing is sealed oil- tight from the inside of the gearbox housing or from the secondary housing. It is thus not possible for oil vapour to pass from the inside of the gearbox housing into the inside of the intermediate housing. A f urther advantage exists in that the output shaft of the electric motor which projects into the intermediate housing need not be sealed from the intermediate housing. This output shaf t mostly rotates at high speed so that such a seal is liable to losses due to friction and is subjected to high demands with regards to its service life. Further advantages of division into a housing open to the shift transmission and an oil-tight housing are: A seal only on a shaf t which only rotates and not on a 35 shaft which rotates and slides, such as the central shift shaft, A stress-free lubricant can be used for lubricating a first transmission stage and A heating of a gearbox element such as for example a worm gearwheel of for example plastics through heat input from the vehicle gearbox can be substantially reduced or avoided.

The sub-claims refer to advantageous further developments and designs of the device according to the invention.

It is advantageous if the intermediate housing is sealed from the gearbox housing by means of a cover through which is guided with the interposition of a seal a component part driven by the intermediate gear. It can further be expedient if the intermediate gearbox is a reduction worm gear whose output shaft is connected to anoperating member of the shift transmission it is likewise expedient if the intermediate gearbox is a reduction spur wheel gear whose output shaft is connected to an operating member of the shift transmission. It can also be advantageous with a further embodiment if the intermediate gearbox is a reduction planetary gearbox whose output shaft is connected to an operating member of the shift transmission.

It is advantageous if the intermediate housing is connected to the motor housing through the interposition of a seal wherein a second seal can be spared.

It is advantageous if an output shaft of the worm gear is formed on the worm wheel and is guided with the interposition of a seal through the cover whereby the output shaft has a bearing bore which is closed oiltight from the inside of the gearbox housing by means of a cap.

it is likewise expedient if an output shaft of the worm gear is formed on the worm wheel and is guided through the cover with the interposition of a seal whereby the output shaft has a bearing bore which is formed in one piece and is closed from the inside of the gearbox housing.

It is also advantageous if the axial drive is formed by a spindle gear whose spindle nut moves a spindle formed on the shift/selector shaft and is integrated in the worm wheel of the intermediate gear formed as a worm gear and driven by the second electric motor.

Furthermore it is expedient if the worm wheel is sealed on both sides of its radially outer worm teeth from an inside of the intermediate housing in which is mounted the worm of the worm gear which is driven by the second electric motor.

It is advantageous if the cover is provided with at least one seal. It is likewise expedient if the device which produces elasticity has a stop at the end of the spring path. Furthermore it is expedient if further gears are provided in front of or after the intermediate gear.

With a further embodiment it is expedient if the operating member of the automated shift transmission consists at least of two axially movable shift/selector shafts, a first electric motor is connected to an axial drive of the first shift/selector shaft through a first intermediate gear housed in a first intermediate housing, and a second electric motor is connected to an axial drive of the second shift/selector shaft through a second intermediate gear housed in a second intermediate housing. It is also expedient if the operating member of the automated shift gear consists of two swivel mounted shift/selector shafts, a first electric motor is connected to a swivel drive of the first shift/selector shaft through a first intermediate gear housed in a first intermediate housing, and a second electric motor is connected to a swivel drive of the second shift/selector shaft through a second intermediate gear housed in a second intermediate housing.

The invention will now be explained in further detail with reference to the drawings in which:

Figure 1 is a partial sectional view of a first embodiment of a device according to the 10 invention; Figure 2 is a plan view, partially in section, of the arrangement according to Figure 1; and Figures 3 to 7 are plan views similar to Figure 1 of further embodiments. is According to Figure 1 an electric motor, serving as a shift actuator, whose motor housing 2 can be seen in plan view is connected to an output shaft 6, to produce rotation thereof, by a worm gear 4. The output shaft projects into a gearbox housing 8 of a shift transmission which is known and therefore not illustrated and whose shift/selector shaft is for example driven in rotation by means of the output shaft 6 of the worm gear 4 in order to execute shift processes when controlled accordingly by the electric motor 2. A device is integrated with the worm gear 4 for producing a predetermined elasticity between the output shaft 10 of the electric motor and the output shaft 6 of the worm gear 4, and contains an entrainment disc 12, a counter disc 14, a hub f lange 16 and springs 18. The construction of the device producing the elasticity is known per se and is therefore not described in further detail.

The worm gear 4 is housed in an intermediate housing 10 which is connected by a flange 22 to the motor housing 2.

The intermediate housing 20 is connected with the interposition of a cover 24 to the gearbox housing 8 for example by means of screws (not shown). The output shaft 6 which is mounted in the intermediate housing 20 and in the form of a sealed rolling bearing 26 in the cover 24 projects through a central opening of the cover 24. Instead of a sealed rolling bearing it is also possible to provide a separate bearing and a separate seal by means of for example a sealing ring or radial shaft sealing ring (RWDR). The bearing can thereby be provided as an antifriction bearing or in another embodiment as a rolling bearing. It is likewise possible to form the seal as a RWDR with lip seal in one structural element. A f ixed axis is also possible.

Sealing rings 28 are provided to seal the gearbox'housing 8 from the cover 24, the cover 24 from the intermediate housing 20 and the intermediate housing 20 from the motor housing 2. Furthermore in a further embodiment a flat seal can be formed. The cover can likewise be caulked.

The kinematic function of the assembly described is known per se and will therefore not be explained in detail. A reliable seal of the interior of the intermediate housing 20 from the inside of the gearbox housing 8 is achieved with the arrangement described so that the output shaft 10 of the electric motor need not be sealed separately from oil and the inside of the motor housing 2 is protected from oil from the gearbox housing 8. A further advantage of the arrangement described is that the seal of the output shaft 6 passing through the cover 24 through the rolling bearing 26 (radial shaft sealing rings could also be used) has the result that this seal is comparatively low in friction and has a high service life since the relative rotation of the output shaft 6 in respect of the cover 24 is small and takes place slowly. A seal of the output shaft 10 from the motor housing 2 or the intermediate housing otherwise required would have the disadvantage that high speeds have to be sealed which is naturally affected by friction.

It is obvious that the entire arrangement is hermetically sealed from the outside owing to the sealing rings 28 so that even under difficult operating conditions inside the motor chamber an operation of the said component parts is guaranteed in clean surroundings.

Figure 2 shows a view from above of the arrangement according to Figure 1 with a horizontal section of the intermediate housing 20 and the counter disc 14 removed.

This figure clearly shows the worm 30 driven by the output shaft 10 of the electric motor and the worm wheel 32 meshing with the worm 30 as well as the springs 18. An elasticity can likewise be formed with an integrated stop. Instead of the worm gear it is also possible to use in another embodiment a spur wheel gear or planetary gear.

Figure 3 shows an embodiment of the device which differs from that shown in Figure 1 mainly in that the device f or producing a predetermined rotational elasticity between the output shaft 10 of the electric motor and the operating member for the gearbox is not housed inside the intermediate housing but inside the gearbox housing or a secondary housing connected to the inside of the gearbox housing. The same reference numbers are used here for the functionally similar component parts as are used in Figure 1.

The output shaft 6 of the worm gear 4 is inthis embodiment sealed from the cover 24 with a radial shaft seal 34. By means of the component parts 12, 14, 16 and 18 the output shaft 6 is rotationally elastic relative to the operating member 36 of the gearbox (not shown) for swivelling its shift/selector shaft.

The function of the assembly according to Figure 3 corresponds otherwise to that of Figure 1 wherein in particular the same tightness and seals are achieved.

The embodiment according to Figure 4 differs from that of Figure 3 mainly in that the output shaf t 6 of the worm gear 4 is formed directly on the worm wheel 38 of the worm gear 4. A bore 40 for the bearing of the worm wheel 38 is closed from the inside of the gearbox housing 8 by an oiltight cap 42 so that in this way no oil can pass from the gearbox into the inside of the intermediate housing 20 and is f rom there into the electric motor. Instead of the oiltight cap the worm gearwheel can also be formed closed in one piece f rom the inside so that at this point no oil passes into the area of the gearbox. With the embodiment according to Figure 3 functionally similar component parts are again provided with the same reference numerals.

Figure 5 shows an arrangement with which the shift/selector shaft of a gearbox (not shown) can be both rotated about its axis and displaced axially so that the shift and selection processes can be executed in the gearbox.

A first electric motor housed in the motor housing 2 drives through the worm gear 4 housed in an intermediate housing 20 a gear wheel 44 mounted in a space which is open to the inside of the gearbox housing. A secondary housing is used for this which is open to the gearbox housing. The arrangement corresponds to that of Figure 1 so that the same reference numerals are used as in Figure 1. The gearwheel 44 meshes with a segment wheel 46 which is mounted in the gearbox housing 8 and is connected to a shift/selector shaft 48 of the gearbox (not shown) through a partial gearing provided by balls 50 so that the shift/selector shaft 48 is connected to the segment wheel 46 rotationally fixed but longitudinally displaceable. As can be seen the gearbox housing 8 in which the shift/selector shaft 48 projects, forms a secondary housing or an attachment of the actual main housing 52 of the gearbox (not shown).

A further electric motor whose housing is marked at 54 serves to axially displace the shift/selector shaft 48. The output shaft 56 of this electric motor drives through a worm gear 58 the worm wheel 60 whose interior circumference forms a spindle nut 62 which during its is rotation moves a spindle 64 formed on the shaft 48 in the linear direction.

The worm gear 58 and the spindle gear formed by the spindle nut 62 and spindle 64 are housed inside an intermediate housing 66 on which the motor housing 54 is fixed and which is connected to the gearbox housing 8 through the interposition of a cover 68. So that the space inside the intermediate housing 66 in which the worm gear 58 is mounted remains reliably free of oil from the gearbox the worm wheel 60 is sealed on both sides of its worm teeth through shaft seals or as shown in the form of sealed rolling bearings 70, 72 on one side from the cover 68 and on the other side from the intermediate housing 66. Thus oil passing through the spindle gear cannot pass into the space of the worm gear 58.

Figure 6 shows a further embodiment of the invention wherein the axis 6a is mounted on the side of the gearbox housing and the worm wheel 38 is mounted on this axis 6a.

The axis 6a can as shown be supported in the gearbox housing. The gap between the axis 6a and the gearwheel 38 can be sealed by means of the seal 101, such as a sealing ring, wherein the sealing ring is mounted on the gearbox side 102 of the axis. It can also be mounted on the side 103 of the axis remote from the gearbox.

Figure 7 shows a further embodiment of the invention. In an advantageous manner it is possible that the worm wheel 38a and gearwheel 38b are connected as two individual parts conducting torque. This connection advantageously takes place through toothed engagement. A seal 105 can be provided in the area of the teeth. The worm gearwheel 110 of Figure 5 can likewise be formed in two parts. The gearwheel and/or worm gearwheel can be formed of metal or plastics. It is likewise advantageous if parts of the device are made from glass fibre reinforced polyamide. Reinforcement of the individual component parts of the device through metal is likewise expedient.

The connection between the electric motor housing, 20 intermediate gearbox housing and gearbox housing is provided in a manner (not shown) through screws, rivets or caulked connections, thus through keyed engagement or friction-locking connections.

The invention is also not restricted to the embodiments of the description. Numerous amendments and modifications are possible within the scope of the invention as defined by the claims. In particular the invention can extend to variations, elements and combinations and/or materials which are combinations or modifications of individual features or elements or process steps contained in the drawings and described in connection with the general description and embodiments.

Claims

1 Device for operating an automated shift transmission containing a gearbox housing, a motor housing, an electric motor in the motor housing, an intermediate gearing driven by the electric motor and whose output member is connected to an operating member of the automated shift transmission, wherein the intermediate gearing is housed in an intermediate housing which is connected to the motor housing and the gearbox housing, the inside of the intermediate housing is sealed oiltight from the inside of the gearbox housing, and a device is provided in the intermediate housing to produce a predetermined elasticity between the output shaft of the electric motor and the operating member of the shift transmission.,

2. Device as claimed in Claim 1, wherein the intermediate housing is sealed from the gearbox housing by means of a cover through which is passed with the interposition of a seal a component part which is driven by the intermediate gearing.

3. Device as claimed in Claim 1 or Claim 2, wherein the intermediate gearing is a reduction worm gear whose output shaft is connected to an operating member of the shift transmission.

4. Device as claimed in Claim 1 or Claim 2, wherein the intermediate gearing is a reduction spur wheel gear whose output shaft is connected to an operating member of the shift transmission.

5. Device as claimed in Claim 1 or Claim 2, wherein the intermediate gearing is a reduction planetary gear whose output shaft is connected to an operating member of the shift transmission.

6. Device as claimed in any preceding claim, wherein the intermediate housing is connected to the motor housing with the interposition of a seal.

7. Device as claimed in Claim 3 or in Claim 6 when dependent on Claim 3, wherein an output shaft of the worm gear is an integral part of the worm wheel and is passed through the cover with the interposition of a seal wherein the output shaft has a bearing bore closed oil-tight from the inside of the gearbox housing by means of a cap.

is

8. Device as claimed in Claim 3 or in Claim 6 when dependent on Claim 3, wherein an output shaft of the worm gear is moulded onto the worm wheel and is passed through the cover with the interposition of a seal wherein the output shaft has a bearing bore which is formed in one piece and is closed oil tight from the inside of the gearbox housing.

9. Device as claimed in any preceding claim, wherein the operating member of the automated shift transmission is an axially movable shift/selector shaft which can swivel about its axis, a first electric motor is connected to a swivel drive of the shift/selector shaft through a first intermediate gear housed in a first intermediate housing and a second electric motor is connected to an axial drive of the shift/selector shaft through a second intermediate gear housed in a second intermediate housing.

10. Device as claimed in Claim 9, wherein the axial drive is formed by a spindle gear whose spindle nut moves a spindle formed on the shift/selector shaft and is integrated in the worm wheel of the intermediate gear formed as the worm gear and driven by the second electric motor.

11. Device as claimed in Claim 10, wherein the worm wheel is sealed on both sides of its radially outer worm teeth from an inside of the second intermediate housing containing the worm of the worm gearing which is driven by the second electric motor.

12. Device as claimed in any one of Claims 2 to 11, wherein the cover is provided with at least one seal.

13. Device as claimed in any preceding claim, wherein the device which produces elasticity includes at least one compression spring and has a stop at the end of a spring compression path.

14. Device as claimed in one of Claims 3 to 5, wherein further gears are connected in front of and behind the intermediate gear.

15. Device as claimed in any preceding claim, wherein the operating member of the automated shift transmission consists of at least two axially movable shift/selector shafts, a first electric motor is connected to an axial drive of the first shift/selector shaft through a first intermediate gear housed in a first intermediate housing and a second electric motor is connected to an axial drive of the second shift/selector shaft through a second intermediate gear housed in a second intermediate housing.

16. Device as claimed in any preceding claim, wherein the operating member of the automated shift gear consists at least of two swivel shift/selector shafts, a first electric motor is connected to a swivel drive of the first shift/selector shaft through a first intermediate gear - is - housed in a first intermediate housing, and a second electric motor is connected to a swivel drive of the second shift/selector shaft through a second intermediate gear housed in a second intermediate housing. 5