Spindle or worm drive for adjustment devices in motor vehicles

A spindle or worm drive for adjustment devices in motor vehicles. The device is secured with a fixed spindle or a fixed toothed rack to the first of two parts which can be adjusted in relation to each other, and is provided with a gear mechanism which is connected to the second of the two parts which can be adjusted in relation to each other. The gear housing is free from backlash and is enclosed by at least one bearing shell such that it is pivotable about at least one axis. The bearing shell consisting of two bearing plates which fit into one another and which can be joined to each other after enclosure of the gear housing. The gear housing is made of plastic and is provided with a concave or convex housing part which is surrounded by a convex or concave bearing shell section made of a material which is suitable for receiving crash forces, especially a metal material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Phase Patent Application of International Application Number PCT/DE2002/04282, filed on Nov. 18, 2002, which claims priority of German Patent Application Number 102 06 524.1, filed on Feb. 13, 2002, and German Patent Application Number 102 50 994.8, filed on Oct. 30, 2002.

BACKGROUND

The invention relates to a spindle or worm drive for adjustment devices in motor vehicles, more particularly for seat adjustment devices, window lifters and sliding roofs.

From DE 198 61 100 A1 a spindle drive is known for adjustment devices in motor vehicles having a fixed spindle which is fixed on a first of two relatively rotatable parts, a gearing mechanism which is mounted on the second of the relatively rotatable parts, and a gear housing for accommodating the gearing. The gear housing consists of two housing plates which are fixed against each other by means of push-fit connections and which are designed as supporting connecting points where the housing plates are held together and which take up the gear forces. The push-fit connections have raised zones and recesses which fit into each other and initially form a play-fit. The housing plates are fixed by plastically deforming the material in the region of the push-fit connections.

From U.S. Pat. No. 4,802,374 a spindle drive is known for a seat longitudinal adjuster in motor vehicles which contains a spindle which is connected to the adjusting rail of the seat longitudinal adjuster and which can be driven through an electric motor by a spindle nut, worm wheel and a worm connected to a motor shaft. The worm, the worm wheel and the spindle nut are mounted in a retaining clip having two cylindrical sleeves which intersect at right angles. A retaining flange which is connected to the base rail of the seat longitudinal adjuster and consists of a clip with a rectangular window-shaped opening surrounds the cylindrical sleeves of the retaining clip through the frame of the window-shaped opening, and thus secures the position of the retaining clip.

With this spindle drive which is known from U.S. Pat. No. 4,802,374 the tolerances of the individual component parts determine the overall play of the spindle drive so that to reduce the clearance of the spindle drive narrow tolerances have to be set which requires considerable manufacturing expense.

A further drawback of the known spindle drives is that the retaining flange does indeed secure the position of the retaining clip but offers no security in the event of a crash since the retaining flange only surrounds a part of the retaining clip and in the event of a crash is bent so that the coupling between the movable adjusting rail and the base rail fixed on the body is released and thus a vehicle seat connected to the adjusting rail will move uncontrollably.

The object of the present invention is therefore to provide a spindle or worm drive for adjustment devices in motor vehicles of the type already described which guarantees a play-free bearing of the gear elements protected against dirt, a crash-safe connection of the gearing mechanism and thus of the adjustment device as well as a bearing of the gearing mechanism which is able to pivot when necessary about at least one axis.

BRIEF DESCRIPTION

The solution according to the invention provides a play-free bearing of the gearing elements protected against dirt as well as a crash-safe support of the gearing mechanism and thus of the relatively movable parts of the adjustment device as well as a pivotal action of the gearing mechanism for connecting adjustment parts which are able to pivot about an axis.

The solution according to the invention is based on the idea of arranging the gear elements in a gear housing surrounding the gear elements in the form of a capsule protected against dirt and damage and of arranging the gear housing in turn free from backlash and where necessary able to pivot about at least one axis in a bearing shell which is designed and intended to take up the crash forces and thus to ensure a crash-safe support of the gear mechanism so that the relatively movable parts of the adjustment device also remain connected together even in the event of a crash.

The gearing housing preferably consists of plastics while the bearing shell is made from a material, more particularly a metal material, which is suitable for absorbing crash forces. This enables on the one hand a simple manufacture of the gear housing, particularly in an injection casting process with high accuracy in fitting while the crash forces are taken up by the bearing shell which is made of metal so that the gear housing itself does not have to be dimensioned to take up the crash forces since these are distributed over a wide surface area over the gear housing through the bearing shell.

The ability of the gear housing to pivot about an axis, for example about a pivotal axis running perpendicular to the spindle or toothed rack is preferably achieved through a concave or convex housing part of the gear housing and a convex or concave bearing shell section which surrounds the concave or convex housing part.

In an exemplary embodiment of the drive the bearing shell is made in two parts; namely the bearing shell consists of two bearing plates which can be fitted into each other and which can be connected together after the gear housing has been fitted and which can be fixed on the second of the two parts which are adjustable relative to each other.

Making the bearing shell from two bearing plates which can be fitted into each other means that it is easy to fit the bearing shell free from backlash on the gear housing since the bearing plates can be placed around the gear housing, pushed together to zero tolerance and then connected together in this position, for example, by laser welding.

The preferably U-shaped bearing plates can be fitted together engaging in each other by means of the side arms in the direction of the longitudinal extension of the spindle or toothed rack whereby the connecting arms between the side arms have through openings for passing through the spindle or toothed rack, adjoined on each side by the concave or convex bearing shell sections which correspond with the convex or concave housing parts of the gear housing.

This design combines the rotational movement of the gear mechanism inside the bearing shell formed by the bearing plates with a clearance-free connection between the gear housing and the bearing shell with integrated guide of the spindle or toothed rack.

The side arms of the one bearing plate are preferably formed as tabs which engage in the other bearing plate in the one side arm provided with a window-shaped opening and the other side arm provided with a U-shaped recess. To compensate for tolerances, the tab-shaped side arm of the one bearing plate is longer in the connecting direction of the bearing plates than the window-shaped opening of the other bearing plate, and the tab-shaped side arm of the one bearing plate is shorter than the U-shaped recess of the side arm of the other bearing plate whereby the tab-shaped side arm of the one bearing plate can be fitted in the connecting direction of the bearing plates through a cut-out section in the connecting arm of the other bearing plate which widens out the window-shaped opening of the corresponding side arm of the other bearing plate.

Since the tab-shaped side arm of the one bearing plate in the connecting direction of the bearing plates is longer than the window shaped opening and the frame surrounding the window shaped opening is longer than the tab shaped side arm, the fixing points provided at the front ends of the tab shaped side arm in the connecting direction, and the frame surrounding the window-shaped opening are freely accessible for attaching the spindle or worm gearing on one of the two parts which are movable relative to each other.

In order to connect the bearing plates while guaranteeing a play-free coupling with the gear housing the side arms of the bearing plates are positively connected together in the assembled state of the adjustment device, more particularly through welding contours.

In a further exemplary embodiment of the drive the bearing shell is designed in four parts and consists of four bearing plates; where basically the bearing shell has a base plate, two side plates and a top plate, wherein the base plate and the top plate run substantially parallel to each other and are held spaced apart yet connected together through the two side plates which are mounted substantially parallel to each other. With this further special embodiment there is the important advantage that the manufacturing tolerances can be compensated particularly easily since the relative position of the four bearing plates (bearing shell plates) relative to each other can be re-aligned very simply. Thus the freedom from backlash between the gear housing and bearing shell can be adjusted and permanently fixed in a very simple manner.

In the further exemplary embodiment, the base plate optionally has two slot like openings of which one serves to hold a fixing tab of one of the two side plates and the other opening serves to hold the fixing tab of the other of the two side plates.

The one side plate can thereby advantageously have a further fixing tab which is mounted on a side of the side plate opposite the one fixing tab and engages in a recess in the edge of the top plate.

Through openings are advantageously provided in each of the side plates for passing through the spindle or toothed rack.

In order to fix the freedom from backlash between the gear housing and the bearing shell in a particularly secure manner it is regarded as advantageous if the side plates and the gear housing lie close against each other over a wide surface area. This can advantageously be achieved if the side plates have concave and convex bearing shell sections with which the gear housing is fixed.

The through openings in the side plates as well as the concave or convex bearing shell sections can thereby be arranged relative to each other so that the concave and convex bearing shell sections are arranged on each side of the through openings for passing through the spindle or toothed rack.

After the base plate, the two side plates and the top plate have been aligned relative to each other and the freedom from backlash between the gear housing and bearing shell is ensured, the base plate, the two side plates and the top plate can be welded together for fixing. In particular, laser welding is regarded as advantageous for fixing purposes. The welded seams for connecting the bearing plates should thereby lie in grooves which are formed in the connecting regions between the bearing plates which stand on one another.

An advantageous method for manufacturing the spindle and/or worm drive according to the invention includes the gearing elements after their connection with the spindle or toothed rack being inserted into a housing shell of the gear housing and being connected to a drive element of the motor shaft so that a gearing cover is connected to the housing shell of the gear housing to close up the gear mechanism and the finished made gear housing being enclosed free from backlash by a bearing shell.

In the case of a two part drive this can advantageously be fitted so that the bearing plates are pushed from both sides through the full-length openings onto the spindle, so that the side arms of the bearing plates are pushed into each other until the concave or convex bearing shell sections of the bearing plates adjoin without play against the concave and convex housing parts of the gear housing, and so that the abutting side edges of the side arms of the bearing plates are connected together by laser welding, at least over a part of their length.

The one end of the spindle can then be connected to a connecting tab which is fixed on the first of the two relatively rotatable parts and the interconnecting bearing plates can be connected to the second of the relatively rotatable parts.

In the case of a four-part bearing shell, it is regarded as advantageous if this is formed from four bearing plates in that two side plates are set up on a base plate, the gear housing is inserted between the two side plates, a top plate is fitted onto the two side plates and the four bearing plates are aligned without play relative to each other and then fixed together.

The two side plates can advantageously be fitted from both sides through window-shaped full-length openings onto the spindle and then aligned until the concave and convex bearing shell sections of the side plates bear without play against the concave and convex housing parts of the gear housing.

Fixing the four bearing plates can advantageously be carried out by welding, more particularly laser welding. In order to avoid “through welding” when laser welding, the join should be “butt” welded, thus welded at an obtuse angle. Laser welding should thereby be carried out in the grooved areas or in the grooves which are formed in the connecting region of the adjoining bearing plates. It is recommended in this connection if the laser welding is carried out at an angle of about 45° to the bearing plates which are to be connected.

DETAILED DESCRIPTION

The spindle drive which is shown in exploded views inFIGS. 1 to 3has an electric motor1whose motor shaft2is connected to a drive worm20which meshes with a worm wheel9of a gear mechanism3. The worm wheel9is connected to a spindle nut8whose thread meshes with the thread of a spindle7. Any rotation of the motor shaft2is transferred through the drive worm20to the worm wheel9and thus to the spindle nut8which is connected in one piece to the worm wheel9so that when the spindle7is mounted rotationally secured it changes its position in relation to the motor shaft2through the rotation of the spindle nut8, i.e. is moved in the direction S1or S2in relation to the motor shaft2according toFIG. 2depending on the direction of rotation of the electric motor1.

The gear elements, drive worm20, spindle8and worm wheel9, are combined into the gear mechanism3which has a gear housing4which consists of a housing shell40and a housing cover41which after inserting the gear elements8,9,20into the housing shell40is connected to the housing shell40.

Two U-shaped bearing plates5,6are fitted onto the ends of the spindle7projecting out from the gear housing4, wherein the side arms52,53and62,63of these bearing plates are aligned opposite one another and their connecting arms51,61which connect the side arms52,53and62,63together have window-shaped through openings55,65for receiving the spindle7. The side arms52,53, and62,63are thus designed so that they can engage in each other with slight play and thereby produce a positive connection which has a certain play. For this purpose the one bearing plate5has two side arms52,53designed as tabs, while the one side arm62of the other bearing plate6has a rectangular window-shaped opening66while the other side arm63is designed U or clip-like and has a corresponding recess67.

If the two bearing plates5,6are inserted in each other then the tab-shaped side arms52,53of the one bearing plate5substantially fill out the window shaped opening66or the recess67of the side arms62,63of the other bearing plate6. For compensating tolerances either the tab-shaped side arms52,53of the one bearing plate5in the joining direction of the bearing plates5,6are either slightly shorter than the length of the window-shaped opening66or recess67of the side arms62,63of the other bearing plate6, or the tab-shaped side arm52of the one bearing plate is longer than the window-shaped opening66of the side arm62on the other bearing plate6and in the connecting direction of the bearing plates5,6can be fitted through a cut out section68in the connecting arm61of the other bearing plate6which widens out the window shaped opening66of the corresponding side arm62of the other bearing plate6so that the tab shaped side arm52of the bearing plate5can project through the window shaped opening66and thus through the connecting arm61of the other bearing plate6, or the frame of the side arm62surrounding the window shaped opening66over the connecting arm51of the bearing plate5, as can be seen from the illustration inFIG. 6. After connecting the bearing plates5,6into the bearing shell the fixing points71,72,73provided at the ends of the upper side arms52,62of the bearing plates5,6and projecting over the relevant connecting arms51,61of the other bearing plate5,6are accessible for fixing the spindle or worm gearing on the one of the two relative movable parts.

In the region of the window-shaped spindle passages55,56through the bearing plates5,6the connecting arms51,61have in relation to the gear housing4concave curvatures54,64which correspond to convex housing sections42,43of the gear housing4, i.e. the housing shell40and the housing cover41. The curvatures42,43of the gear housing4and the curvatures54,64of the connecting arms51,61correspond with each other so that the gear mechanism3can swivel inside the bearing shell formed from the bearing plates5,6about an axis running parallel to the motor shaft2and thus can compensate pivotal movements of the parts which are movable relative to each other, of which one part is connected through a fixing tab70to the spindle7and the other of the two relatively movable parts is connected through the fixing points71,72,73to the bearing shell which is formed by the bearing plates5,6.

In order to assemble the spindle or worm drive the gear elements, namely the worm wheel9and the spindle nut8, after their connection with the spindle7, they are inserted into the housing shell40of the gear housing4and are connected to the worm20which is attached to the motor shaft2. After fitting the housing cover41onto the housing shell40and connecting it to the gear housing4the gear mechanism3is complete. The bearing plates5,6are then pushed from both sides via the window shaped through openings55,65onto the spindle7and the side arms52,53;62,63of the bearing plates5,6are pushed into each other and the concave and convex bearing shell sections54,64of the bearing plates5,6bear without play against the concave and convex housing parts42,43of the gear housing4. Finally the abutting side edges521,522,661,662;531,532,671,672of the side arms52,62and53,63of the bearing plates5,6are connected together by means of laser welding which run as welding contours74,75,76at least over a part of the length of the side edges521,522,661,662;531,532,671,672.

In order to connect the spindle or worm drive to the adjusting drive the one end of the spindle7is connected to the fixing tab70which is fixed on the first of the two relatively movable parts while the bearing plates5,6which are connected together to form the bearing shell are connected to the second of the relatively movable parts.

In the assembled state of the gear mechanism3and the bearing shell formed from the bearing plates5,6as illustrated inFIGS. 4 to 6, the side edges521,522and531,532of the tab-shaped side arms52,53of the one bearing plate5are located adjoining the inner side edges661,662and671,672of the window shaped opening66and recess67respectively of the side arms62,63of the other bearing plate6. As can be seen from the perspective illustrations of the assembled drive according toFIG. 4 to 6, the ends of the tab-shaped side arm52of the one bearing plate5and of the end of the side arm62of the other bearing plate6defining the window shaped opening66project over the relevant connecting arms51,61of the relevant other bearing plate5,6and enable a corresponding match to the dimensions of the gear housing4in the connecting region so that a play-free connection between the gear mechanism3and the bearing shell5,6is guaranteed.

An embodiment for a drive according to the invention is shown inFIGS. 7 to 16where the bearing shell consists of four bearing plates.

InFIG. 7a base plate800is shown which has two slit like openings810. A side plate820with a fixing tab830is pushed into one of the two slit like openings810of the base plate800; this is shown in detail inFIG. 8. The side plate820furthermore has a further fixing tab840which is described further below in connection with the fixing of the side plate820on a top plate.

In the illustration according toFIG. 9a second side plate850is pushed by its fixing tab860onto the base plate800. It can be seen inFIG. 9that the width of the slit like openings810is slightly larger than the width of the associated fixing tabs830and860so that the two side plates820and850have a slight clearance and thus are fixed easily movable on the base plate800.

FIGS. 10 and 11show how the gear housing4already described in further detail above in connection withFIGS. 1 to 6is inserted with the electric motor1into the arrangement which comprises the base plate800and the two side plates820and850.FIG. 10thereby shows a view from inclined left andFIG. 11shows a view from inclined right.

Furthermore it can be seen inFIGS. 10 and 11that each of the two side plates820and850each has a through opening870and880. Left and right of the through openings870and880—thus on both sides of the through openings870and880—each of the two side plates820and850each has two concave and convex bearing shell sections890,900,910and920. The through openings870and880serve for passing through the spindle7which is shown in further detail for example inFIG. 1and which is described above in connection withFIG. 1.

InFIG. 12a top plate930is shown which has a recess940along the edge. The edge recess940serves—as described in detail further down in connection with FIGS.13to16—to receive the further fixing tab840of the one side plate820.

FIGS. 13 and 14show the finished assembled drive after the gear housing4has been inserted between the two side plates820and850. In particular it can be seen easily fromFIG. 13how the concave and convex bearing shell sections890,900,910and920bear30without clearance against the gear housing4which has a concave shape in the fixing area. InFIG. 13it can further be seen how the top plate930is fixed on the two side plates820and850. Also seen is the further fixing tab840of the one side plate820which engages in the recess940along the edge of the top plate930. On the side950of the top plate930opposite the edge recess940the top plate930rests on the second side plate850.

FIG. 14shows the assembled drive from the back. It is possible to see the electric motor1and the base plate800as well as the slit like openings810into which the fixing tab830of the one side plate820as well as the fixing tab860of the second side plate850engage. Furthermore it is possible to see how the further fixing tab840of the one side plate820engages in the edge recess940of the top plate930.

FIGS. 15 and 16show in detail how the four bearing plates800,820,850and930are connected and fixed together after the gear housing4has been inserted into the bearing shell960which is formed by these bearing plates. In the connecting regions between the bearing plates800,820,850and930there are grooved zones or grooves which carry the reference numerals970,980,990and1000inFIG. 15. The four bearing plates are thereby welded together in these grooved zones970,980,990and1000, thus through “grooved seam welding”. Grooved seam welding has the advantage over welding along the butt joints between adjoining connecting parts that no full penetrating welding passes through the seam point.

FIG. 15also contains arrows1010,1020,1030and1040which are to represent the welding direction of a welding laser beam. It can be seen that the welding direction of the laser beam stands at an angle of about 45° to the bearing plates which are to be connected together. A particularly solid welding seam is formed by an angle of about 45°. The welding seams thus formed carry the reference numerals1050,1060,1070and1080inFIG. 15.

InFIG. 16the connection between the second side plate850and the top plate930is shown once more in detail. The groove980is shown into which the laser beam1090is directed. The laser beam1090thereby has an angle of about 45° to the second side plate850as well as an angle of about 45° to the top plate. “Full penetrating welding” can thus not occur.