DE102010001844B4 - spindle gear - Google Patents

Abstract

Spindle gear, with- a spindle (1) extending in a longitudinal direction (L),- a drive worm (4) of an adjusting gear (2) and- a spindle nut (3) of the adjusting gear (2), which has internal teeth (30). of the spindle (1) and via an external toothing (31) with the drive worm (4) in engagement in such a way that by driving the drive worm (4) the spindle nut (3) can be set in rotary motion in order to rotate the adjusting gear (2) along the To adjust the spindle (1), the spindle nut (3) being cylindrical in at least one middle section with an outer cylindrical lateral surface (32) and two end faces (33, 34) laterally delimiting the cylindrical lateral surface (32) and the external teeth (31 ) of the spindle nut (3) is formed by radially inward-pointing indentations in the outer cylindrical lateral surface (32) of the spindle nut (3), characterized in that the external teeth (31) extend from the one, first end face (33) along the cylindrical Lateral surface (32) extends in the direction of the other, second end face (34) with a tooth depth (H) which decreases towards the second end face (34), the external toothing (31) being open laterally on the first end face (33), and that the internal toothing (30) of the spindle nut (3) is offset in the longitudinal direction (L) to the external toothing (31) of the spindle nut (3) such that a central plane (MA) of the external toothing (31) running perpendicularly to the longitudinal direction (L) corresponds to a central plane (MI) of the internal teeth (30) is spaced.

Description

The invention relates to a spindle drive according to the preamble of claim 1.

Such a spindle gear is used, for example, in vehicles as an adjusting device for adjusting two vehicle parts relative to one another, for example for longitudinal adjustment of a vehicle seat. Such a spindle gear has a spindle extending in a longitudinal direction and an adjustment gear arranged on the spindle with a spindle nut and a drive worm. The spindle nut is in engagement with the spindle via an internal toothing and with the drive worm via an external toothing in such a way that by driving the drive worm the spindle nut can be set in rotary motion in order to adjust the adjusting gear in the longitudinal direction along the spindle.

At one from the WO 2005/015054 A1 known spindle nut of an adjusting gear, the spindle nut is cylindrical in at least one central section with an outer cylindrical surface and two end faces laterally delimiting the cylindrical surface. The external toothing of the spindle nut is formed by depressions pointing radially inwards in the outer cylindrical surface of the spindle nut, so that the teeth of the external toothing do not protrude radially beyond the cylindrical surface of the spindle nut.

In order to enable a simple, light and inexpensive design of the adjustment gear, a gear housing of the adjustment gear and the spindle nut can be made of plastic, the spindle nut made of plastic with its plastic external teeth also contributing to minimizing noise during an adjustment movement.

The fact that the external toothing is formed by radially inwardly pointing depressions in the outer cylindrical surface of the spindle nut and in which from the WO 2005/015054 A1 known spindle nut, is laterally delimited by tooth-free end sections, for example used for storage, the production of the spindle nut from plastic, for example by injection molding, is comparatively complex, since the radially inward-pointing depressions have to be formed individually by so-called slides in the injection mold.

It is the object of the present invention to provide a spindle gear which, on the one hand, satisfies the strength requirements for such a spindle gear and whose spindle nut, on the other hand, can be produced easily, in particular by plastic injection molding.

This object is solved by an object with the features of claim 1.

It is provided that the external toothing extends from the one, first end face along the cylindrical lateral surface in the direction of the other, second end face with a tooth depth that decreases towards the second end face.

Because the external toothing extends from the one, first end face (i.e., starts immediately at the first end face), a spindle nut is created whose external toothing is laterally open at the first end face. In other words, the external toothing on the first end face is not limited in the longitudinal direction, so that an injection molding tool for removing the spindle nut from the mold can be removed in the longitudinal direction from the spindle nut.

The background here is that when the spindle nut is made of plastic, the spindle nut is injection molded in an injection mold and then has to be removed from the injection mold. This process is referred to as "demolding". Due to the fact that the external toothing is open in the longitudinal direction on the first end face and not limited laterally, and the tooth depth of the external toothing decreases continuously or in sections (i.e. gradually in discrete steps) in the direction of the second end face, the spindle nut can be easily removed from the mold in Longitudinally pulled out of the injection mold, no slides are required for injection molding of the external teeth and the injection molding can be produced in one operation in an injection mold without a slide. This simplifies the manufacturing process considerably compared to conventional spindle nuts, in which an external toothing has to be formed by radially inward-pointing indentations by radially inserting slides.

The external gearing of the spindle nut can have at least two different gearing sections in the longitudinal direction, of which a first gearing section has cylindrical gearing with constant tooth depth and a second gearing section has non-cylindrical gearing with tooth depth decreasing towards the second end face. In this case, the tooth depth is defined as the radial distance between the tooth base and the enveloping toothing cylindrical lateral surface measured in the radial direction.

In the first toothing section with cylindrical toothing, the external toothing can have, for example, an involute profile with a straight tooth base and constant tooth depth. In the second toothing section, the tooth depth changes and decreases toward the second end face, with the tooth base being able to be arched, for example, and increasing in the radial direction.

The tooth base can have a radius that is smaller than or equal to the maximum tooth depth of the external toothing.

It is also conceivable and advantageous to form the external toothing in the second toothing section as globoidal toothing with teeth that are adapted to the external toothing of the drive worm and whose tooth depth decreases in the direction of the second end face. In this case, the tooth base of the globoidal toothing has a radius that is larger than the maximum tooth depth.

In any case, the tooth depth decreases toward the second end face of the middle section of the spindle nut, so that the tooth depth is reduced to zero at or before the second end face.

By using a globoidal toothing in sections of the external toothing, an external toothing is created which can also transmit large adjustment forces introduced via the drive worm with sufficient strength. The globoidal toothing is adapted to the toothing of the drive worm for a favorable power transmission in such a way that the shape of the individual teeth with their tooth base and their tooth flanks is adapted to the toothing of the drive worm for an optimized surface contact.

The tooth depth of the external toothing decreases toward the second end face, wherein the tooth depth can be reduced to zero before reaching the second end face, resulting in an end section without external toothing at the second end face. This cylindrical end section on the lateral surface of the spindle nut can be used, for example, as a bearing section for the spindle nut.

On the other hand, the external toothing is not delimited by an end section on the first end face, so that the external toothing on the first end face is open laterally and, as explained above, the spindle nut can be produced in a simple manner by plastic injection molding without using additional slides in the injection mold.

In principle, it is possible to design the external gearing of the spindle nut as straight gearing or as helical gearing. When using spur gearing, the teeth of the external gearing are directed along the longitudinal direction and thus along the spindle. In the case of helical gearing, the teeth point obliquely to the longitudinal direction.

The spindle nut engages with the drive worm via the external toothing and is set in rotary motion to operate the adjustment gear. The rotational movement of the spindle nut is converted into a longitudinal movement of the adjusting mechanism along the spindle by engaging its internal teeth in an external thread of the spindle. The spindle nut is designed in such a way that the internal toothing is offset along the longitudinal direction to the external toothing, so that a central plane of the external toothing running perpendicular to the longitudinal direction is spaced axially from a central plane of the internal toothing. The result is a spindle nut that is asymmetrical in the longitudinal direction with an asymmetrical flow of force, in which the center of gravity of the external toothing is spaced apart from the center of gravity of the internal toothing along the longitudinal direction.

The internal toothing of the spindle nut can advantageously have a greater length in the longitudinal direction than the external toothing of the spindle nut, for example by the internal toothing extending axially beyond the external toothing of the spindle nut into a bearing collar of the spindle nut arranged on the first end face. The bearing collar serves to mount the spindle nut on a gear housing of the adjusting gear.

In one embodiment, the spindle nut is designed as a hybrid spindle nut, which has a functional part that is arranged in the power flow between the drive worm and the spindle and forms the middle section, and at least one strength part that diverts crash forces from an adjustment rail, on which the adjustment gear is arranged, into the spindle. The division of the hybrid spindle nut into a functional part and a strength part makes it possible to optimize both parts of the hybrid spindle nut with regard to the function assigned to them, both in terms of design and in terms of material selection, and thus the advantage of a simple, light, and cost-effective construction with a very to provide sufficient stability and in particular crash resistance of the spindle drive over a wide temperature range.

Accordingly, the functional part and the at least one strength part of the hybrid spindle nut consist of different materials adapted to the respective strength requirements or have different material components adapted to the respective strength requirements, with the functional part in particular being arranged in a central area of the hybrid spindle nut and containing the external and internal teeth of the hybrid spindle nut in the power flow between the drive worm and the spindle. The at least one strength part can form an end face of the hybrid spindle nut and consist, for example, of at least one bushing forming the end face of the hybrid spindle nut.

The external toothing and the internal toothing of the spindle nut are advantageously formed on the functional part, and the strength part of the hybrid spindle nut adjoins the second end face of the functional part in the longitudinal direction. The hybrid spindle nut, which consists of a functional part and at least one strength part made of different materials, is therefore made entirely of plastic in the middle functional part or at least in the toothing area of the external and internal teeth, while the axially outer area of the hybrid spindle nut that forms the strength part is provided with a bushing that has a higher strength than the functional part of the hybrid spindle nut due to a corresponding choice of material or material composition, so that the transmission of crash forces to a gear housing or a bracket for connecting the adjustment gear to an adjustment rail is guaranteed, so that they can dig into the external thread of the spindle in the event of a crash .

If only one-sided crash resistance is required even at extreme temperatures, the strength part of the hybrid spindle nut can be provided on only one side assigned to the respective crash in the axially outer area of the hybrid spindle nut, while the area on the other side of the hybrid spindle nut can be made of a material of lower strength or is made from the material of the functional part of the hybrid spindle nut.

In a preferred embodiment, the at least one rigid part, for example a bushing of the hybrid spindle nut, has internal teeth whose tooth flanks are spaced apart from the tooth flanks of the external thread of the spindle in such a way that during normal operation only the internal toothing of the functional part engages with the external thread of the spindle.

The bush of the hybrid spindle nut, which forms the strength part, replaces the function of an additional thrust washer at the front end of the hybrid spindle nut, while the formation of a large backlash between the internal teeth of the bush and the external thread of the spindle ensures that the internal teeth of the bush do not interfere with the external thread of the spindle during normal operation intervenes, i.e. "idles". Only in the event of a crash, when the tooth flanks of the internal plastic toothing of the functional part of the hybrid spindle nut deform, do the internal toothing of the strength part or the bushing engage in the external thread of the spindle and thus ensure that the crash force is dissipated by the adjustment rail (e.g. a longitudinal adjustment of a motor vehicle seat) is derived via a gear housing or a bracket and the metal bushing forming the strength part of the hybrid spindle nut into the fixed spindle.

The functional part of the hybrid spindle nut preferably consists of a hollow-cylindrical base body with a cylindrical ring-shaped recess arranged on at least one end face, into which a cylindrical ring-shaped projection of the bushing of the hybrid spindle nut designed as a strength part engages, with the cylindrical ring-shaped projection of the bushing being attached to the end face of the hollow-cylindrical base body of the Functional part resting flange and connect to the flange a cylindrical shoulder and an end face of the functional part designed as a hollow cylindrical base body has a radially flush with the tip circle of the external teeth of the functional part flange.

The division of the hybrid spindle nut according to the invention into a functional part and a strength part can be implemented in different ways.

In a first variant, the at least one bushing designed as a strength part is connected to a hollow-cylindrical base body of the functional part by gluing or laser welding, with the strength part of the hybrid spindle nut containing a hard metal material, in particular steel, or consisting of a hard metal material and the functional part at least in the engagement area of the Internal and external teeth are made of plastic or the strength part is designed as an insert part made of a hard metal body encapsulated with plastic and the functional part consists of a metal material encapsulated with plastic or made of plastic.

Alternatively, the strength part can be made of a high-strength plastic and the functional part can be made of a low-strength plastic.

In a second variant, the functional part is made of plastic, which is attached to the at least one socket designed as a strength part is injection molded.

In a third variant, the main body of the hybrid spindle nut consists of a hollow-cylindrical body made of a metallic material, in particular steel, with narrow tooth flanks as an internal thread, which is encapsulated with plastic on the inside and at least in the area of the external thread of the functional part.

In a fourth variant, the main body of the hybrid spindle nut consists of two hollow-cylindrical half-shells made of metal, which are enclosed in the area of the end faces by two sleeves serving as a strength part, while a plastic forming the internal and external toothing of the hybrid spindle nut is attached to the inner and outer surface of the hollow-cylindrical half-shells sprayed on.

In a further embodiment, a reinforcement part can also be provided as part of the spindle gear, which supports the adjustment gear in relation to the adjustment rail, on which the adjustment gear is arranged, in the longitudinal direction of the spindle in such a way that, due to the reinforcement part, the adjustment gear is in the longitudinal direction of the adjustment rail forces introduced into the adjustment mechanism have a higher rigidity in relation to the adjustment rail than in the case of forces introduced counter to the longitudinal direction.

For example, it can be provided that the reinforcement part supports the adjusting gear on one side by supporting the adjusting gear against forces acting in the longitudinal direction and introduced into the adjusting gear by the adjusting rail, but not against forces acting against the longitudinal direction. For this purpose, the reinforcement part (especially if the spindle gear is used to adjust the length of a vehicle seat) can be arranged in the longitudinal direction of the spindle behind the adjustment gear (where the longitudinal direction of the spindle corresponds to a vehicle longitudinal direction in the direction of the vehicle traveling ahead), in order to prevent the inertia in a front crash of the vehicle seat and a vehicle occupant in the adjustment mechanism to support forces.

The idea here is to provide a reinforcement part that supports the adjusting gear on one side and acts between the adjusting gear and the adjusting rail on which the adjusting gear is arranged. The reinforcement part is designed to absorb and support forces in the longitudinal direction of the spindle, so that when a force acts in the longitudinal direction of the spindle, the adjusting gear is rigidly supported in relation to the associated adjusting rail. The reinforcement part can be designed so that it is loaded in the longitudinal direction when a force is applied and ensures a rigid connection of the adjusting gear, but is not loaded when the force is reversed against the longitudinal direction and the connection of the adjusting gear to the associated adjusting rail is not stiffened. In this way it can be achieved that, for example in a front crash, the adjustment gear is rigidly connected to the adjustment rail and cannot deform, but in a rear crash, i.e. in the event of an opposing force effect, the connection of the adjustment gear to the associated adjustment rail has less rigidity and a deformation of the adjustment gear and/or its connection is permitted, which leads to a predetermined maximum offset between the vehicle parts connected via the adjustment gear and the spindle. In this way, a vehicle seat can be held with high rigidity in a front crash, while in a rear crash a certain displacement of the vehicle seat is made possible by deformation in the sense of a crumple zone, which reduces the forces transmitted to a vehicle occupant in a rear crash and a rearward displacement that could lead to whiplash.

A prerequisite for using such a reinforcement part is a sufficiently crash-resistant spindle nut, for example in the form of a hybrid spindle nut that can absorb large loading forces. Because in a front crash, the adjustment gear is supported in a stiff manner by the effect of the reinforcement part, so that a bracket holding the adjustment gear cannot deform and dig into the spindle to support crash forces. The forces acting in the event of a frontal crash must therefore be withstood by the (hybrid) spindle nut in order to prevent the spindle nut from slipping as a result of the internal gearing being destroyed.

If an adjusting gear with a hybrid spindle nut is used in combination with a reinforcement part, the strength part of the hybrid spindle nut is arranged on the side of the hybrid spindle nut facing the reinforcement part.

If support is not only desired on one side, another reinforcement part of the same type can of course also be provided, which is arranged in the longitudinal direction in front of the adjusting gear to absorb forces introduced in a rear-end crash, which means that even in the event of a rear-end crash a rigid connection of the adjusting gear to d associated adjustment rail guaranteed.

In order to support forces introduced in the longitudinal direction of the spindle, the reinforcement part can have support ribs, for example. If the reinforcement part has a U-shape in cross-section transversely to the longitudinal direction of the spindle, these support ribs can be formed by the legs of the U-shape. If the adjusting gear protrudes from the adjusting rail in a vertical direction transverse to the longitudinal direction of the spindle, the support ribs then advantageously extend in parallel planes spanned by the vertical direction and the longitudinal direction, so that forces directed in the longitudinal direction act in the plane of the support ribs and thus can be advantageously supported via the support ribs. In order to support forces introduced in the longitudinal direction, the support ribs are arranged in the longitudinal direction behind the adjusting gear and produce a rigid connection of the adjusting gear when such a force is applied.

In another embodiment, the reinforcement part can also be designed as a cuboid block arranged on the adjustment rail, which is designed to absorb forces introduced in the longitudinal direction of the spindle essentially without deformation. The block is also arranged in the longitudinal direction behind the adjusting gear and supports forces acting in the longitudinal direction, so that when forces are introduced in the longitudinal direction, for example in a front crash, a rigid connection of the adjusting gear to the guide rail, for example, is ensured.

The provision of the reinforcement part means that the adjusting gear and its connection to the adjusting rail are supported on one side. With the inclusion of the reinforcement part, the connection can be dimensioned and dimensioned in such a way that when forces are introduced in the longitudinal direction from the adjustment rail into the adjustment mechanism, an offset between the adjustment rail and a rail fixed to the body, on which the spindle is arranged, due to the supporting effect of the reinforcement part. of less than 10 millimeters, preferably less than 5 mm, and with forces introduced counter to the longitudinal direction from the adjustment rail into the adjustment mechanism, an offset between the adjustment rail and the rail fixed to the body of between 20 and 40 millimeters, preferably about 30 millimeters, can occur. By providing the reinforcement part, a substantially rigid and dimensionally stable connection with a minimal offset is made available when a force is applied in the longitudinal direction, while a deformation in the sense of a crumple zone with a noticeable offset is made possible when the force is applied in the opposite direction. For example, in the event of a front crash, deformation can be largely ruled out, so that no misalignment occurs, while in the event of a rear crash, the adjustment rail and the rail fixed to the body are offset by a distance with deformation of the connection, in order in this way to reduce the forces acting on a vehicle occupant dampen

• 1 eine Ansicht eines Spindelgetriebes mit einer Spindel und einem daran angeordneten Verstellgetriebe;
• 2 eine Ansicht der Bauteile eines Verstellgetriebes;
• 3 eine Ansicht einer Spindelmutter bestehend aus einem eine Außenverzahnung und eine Innenverzahnung tragenden Funktionsteil und einem Festigkeitsteil zur Ableitung von Kräften;
• 4 eine Schnittansicht der Spindelmutter gemäß 3;
• 5A eine Seitenansicht der Spindelmutter entsprechend der Ansicht in 3;
• 5B eine Schnittansicht der Spindelmutter entlang der Linie A-A gemäß 5A;
• 5C eine Schnittansicht der Spindelmutter entlang der Linie B-B gemäß 5A;
• 6 eine Ansicht eines Spindelgetriebes mit einem Verstärkungsteil zum einseitigen Abstützen eines Verstellgetriebes;
• 7 eine perspektivische Ansicht des Verstärkungsteils;
• 8A eine schematische Ansicht darstellend die Abstützwirkung des Verstärkungsteils bei einem Frontcrash und
• 8B eine schematische Ansicht darstellend die Deformation des Verstellgetriebes und eines das Verstellgetriebe haltenden Haltewinkels bei einem Heckcrash.

The idea on which the invention is based is to be explained in more detail below with reference to the exemplary embodiments illustrated in the figures. Show it:

• 1 a view of a spindle gear with a spindle and an adjustment gear arranged thereon;
• 2 a view of the components of an adjusting mechanism;
• 3 a view of a spindle nut consisting of an external toothing and an internal toothing-bearing functional part and a strength part for dissipating forces;
• 4 a sectional view of the spindle nut according to FIG 3 ;
• 5A a side view of the spindle nut according to the view in 3 ;
• 5B a sectional view of the spindle nut along the line AA according to 5A ;
• 5C a sectional view of the spindle nut along the line BB according to 5A ;
• 6 a view of a spindle gear with a reinforcement part for one-sided support of an adjusting gear;
• 7 a perspective view of the reinforcement part;
• 8A a schematic view showing the supporting effect of the reinforcement part in a front crash and
• 8B a schematic view showing the deformation of the variator and a bracket holding the variator in a rear-end crash.

a in 1 The spindle gear shown has a spindle 1 arranged on a (only schematically indicated) rail 92 fixed to the body, which is in engagement with an adjustment gear 2, which is connected to a (schematically indicated) adjustment rail 91 of a longitudinal seat adjustment, for example one sliding on the (lower) rail fixed to the body. Rail 92 mounted upper rail, is connected to a motor vehicle seat. A bracket 5, preferably made of metal and in particular made of steel, is used to fasten the adjusting mechanism 2 to the adjusting rail 91, which has a base 50 and two lateral legs 51, 52 on which each passage openings 53, 54 for the spindle 1 are arranged. A fastening flange 55, 56 with a fastening point 57, 58 in the form of a fastening opening protrudes from the two lateral legs 51, 52 of the bracket 5, between which the adjustment gear 2 is arranged and the base 50, via which the bracket 5 can be attached to the Adjustment rail is attached.

The adjusting gear 2 has a gear housing 6 in which a spindle nut 3 and a drive worm 4 are arranged and mounted. The spindle nut 3 contains an internal toothing which meshes with the external thread 10 of the spindle 1 and an external toothing which meshes with the drive worm 4 . During operation of the spindle gear, the spindle nut 3 is set in rotary motion by the drive worm 4 connected to a drive device, which is transferred to a longitudinal movement of the adjusting gear 2 relative to the spindle 1 by the engagement of the internal toothing of the spindle nut 3 in the external thread 10 of the spindle 1. so that the adjusting gear 2 is adjusted relative to the spindle 1 connected to the vehicle in a fixed and non-rotatable manner and the adjustment rail connected to the adjusting gear 2 for longitudinal seat adjustment of the motor vehicle seat and thus the motor vehicle seat is adjusted in the longitudinal direction of the spindle 1 relative to the motor vehicle floor.

In order to ensure that the adjusting rail 91 is held securely and firmly, the adjusting gear 2 is dimensioned in such a way that it can absorb and support the forces introduced by the adjusting rail during a normal adjustment movement of the motor vehicle seat. However, in the event of a crash, particularly in the event of a front or rear crash of the motor vehicle, it must be ensured that the adjusting gear 2 does not slip in the longitudinal direction of the spindle 1, since this would lead to an undesirable acceleration of the motor vehicle seat connected to the adjusting rail of the longitudinal seat adjustment and thus to an increased Risk of injury for a motor vehicle occupant located on the motor vehicle seat would result.

In order to enable a simple, light and inexpensive design of the adjustment gear 2, the gear housing 6 and the spindle nut 3 are preferably made of plastic, the plastic spindle nut with its plastic teeth also contributing to minimizing noise during an adjustment movement.

To increase the strength and stability of the adjusting gear 2, the adjusting gear 2 is surrounded by the metal bracket 5 and connected to the adjustment rail of the longitudinal seat adjustment via the bracket 5, so that in the event of a crash, the bracket 5 is deformed by the spindle nut 3 and the gear housing 6. until, depending on whether a front or rear crash occurs, the respective through-opening 53, 54 of the bracket 5 digs into the threads of the external thread 10 of the spindle 1 and as a result, in the event of a crash, the motor vehicle seat connected to the adjustment gear 2 via the adjustment rail of the longitudinal seat adjustment against an undesirable longitudinal displacement secures.

2 shows a perspective view of the individual elements of the adjusting mechanism 2 according to FIG 1 .

The gear housing 6 of the adjusting gear 2 consists of two housing shells 61, 62 with bores 67, 68 arranged therein for receiving the drive worm 4 and two bearing blocks 63, 64 with bearing bores 65, 66 arranged therein for receiving the hybrid spindle nut 3, which are designed as helical gearing External toothing 31 meshes with the worm gearing 40 of the drive worm 4 and its in 2 not recognizable internal toothing in the assembled state of the spindle drive according to 1 is in engagement with the external thread 10 of the spindle 1 .

Furthermore shows 2 the gear housing 6 of the variator 2 receiving bracket 5, the structure and function above with reference to 1 was described.

• - einem die Außenverzahnung 31 und die Innenverzahnung 30 tragenden Funktionsteil 7, das im Kraftfluss zwischen der Antriebsschnecke 4 und der Spindel 1 zum Übertragen von Verstellkräften im Betrieb des Spindelgetriebes steht, und
• - einem Festigkeitsteil 8, das zur Kraftableitung von Crashkräften von der Verstellschiene 91 in die Spindel 1 dient.

In order to meet the crash resistance requirements of the spindle gear even under extreme climatic conditions with temperatures ranging from -30°C to +80°C and in the event of a crash to be able to transmit forces acting from the spindle nut 3 via the gear housing 6 to the bracket 5, in order to deform it for the clawing in the spindle 1, the spindle nut 3, as in 3 and 4 shown, designed as a hybrid spindle nut with

• - A functional part 7 carrying the external toothing 31 and the internal toothing 30, which is in the power flow between the drive worm 4 and the spindle 1 for the transmission of adjusting forces during operation of the spindle gear, and
• - A strength part 8, which is used to dissipate crash forces from the adjustment rail 91 in the spindle 1.

By using the spindle nut 3 designed as a hybrid spindle nut, a spindle gear is created whose stability and crash resistance while maintaining a simple, light noise caused by the plastic teeth optimized and cost-effective design of the variable speed gear are guaranteed even at extreme temperatures. In particular, the strength part 8 prevents the spindle nut 3 from slipping, even under heavy loads.

In the 3 and 4 The spindle nut 3 shown is composed of the functional part 7 carrying the external toothing 31 and the internal toothing 30 and the strength part 8 attached to the functional part 7 on one side. The strength part 8 engages via a cylindrical ring-shaped projection 81 in a cup-shaped depression 71 (see Fig 5B) of the functional part 7 and is, for example, glued or welded to the functional part 7 .

The strength part 8 has an internal toothing 80, the teeth, as shown 5B clearly visible, are narrower than the teeth of the internal toothing 30 of the functional part 7 and are spaced apart from the external thread 10 of the spindle 1 in the operational state of the spindle nut 3 . In other words, the tooth flanks of the teeth of the internal toothing 80 of the strength part 8 are at a distance from the tooth flanks of the external thread 10 of the spindle 1 in the operational state, so that the internal toothing 80 of the strength part 8 is not in engagement with the external thread 10 of the spindle 1. The strength part 8 is thus rotated together with the functional part 7 during operation of the spindle gear, but without being in contact with the external thread 10 of the spindle 1 and thus without contributing to the friction of the spindle nut 3 .

The strength part 8 rests via a flange 82 on an end face 34 of the functional part 7 and has a cylindrical bearing collar 85, via which and a bearing collar 76 formed on the functional part 7 the spindle nut 3 is mounted on the bearing bores 65, 66 of the bearing blocks 63, 64 .

The strength part 8 is made of a different material than the functional part 7, in particular a stronger material. For example, the strength part 8 can be formed from a hard metal, while the functional part 7 is made entirely or at least partially from a plastic. The purpose of the strength part 8 is to increase the strength of the spindle nut 3 and to prevent the spindle nut 3 from slipping under high loading forces, particularly in the event of a crash, by the internal teeth 80 of the strength part 8 clawing into contact with the external thread 10 of the spindle 1.

On the bearing collar 76 of the functional part 7, spacer ribs 77 are also formed, which extend axially along the longitudinal direction L of the spindle 1 and serve to support a thrust washer 11, which is arranged loosely and non-rotatably on the functional part 7 in order to provide the functional part 7 with a end face 33 ( 5B) slidably supported on the associated bearing block 63, 64 in the longitudinal direction L.

How out 4 As can be seen, the length X of the internal toothing 30 of the functional part 7 engaging with the external thread 10 of the spindle 1 is greater than the length Z of the internal toothing 80 of the strength part 8 and in particular also greater than the length Y of the external toothing 31 of the functional part 7. In the longitudinal direction L, the internal toothing 30 thus extends over a greater length X than the external toothing 31, which further increases the strength of the spindle nut 3 against slipping in the longitudinal direction L.

In principle, two strength parts 8 on either side of the functional part 7 can also be used. In this case, the length X of the internal teeth 30 would be shorter than the length Y of the external teeth 31.

How out 4 and 5B As can be seen, a center plane MA of the external toothing 31 and a center plane MI of the internal toothing 30 are spaced apart from one another in the longitudinal direction L by a distance A. In other words, the centers of gravity of the external toothing 31 and the internal toothing 30 are apart in the longitudinal direction L, resulting in an asymmetrical spindle nut 3 with an asymmetrical introduction of force into the spindle 1 . While the power of the drive worm 4 via the external teeth 31 in the center of gravity in the middle plane MA, the power is transmitted to the spindle 1 through the internal teeth 30 in the center of gravity in the middle plane Ml.

How out 4 and 5B As can be seen, the internal toothing 30 extends into the area of the bearing collar 76 and thus axially beyond the external toothing 31 .

The asymmetrical design of the spindle nut 3 with the internal toothing 30 offset axially to the external toothing 31 enables the use of the strength part 8 with internal toothing 80 arranged on it and spaced apart in the operational state on the one hand and a long internal toothing 30 for the transmission of adjustment forces on the other.

The external toothing 31 on the functional part 7 is designed as a helical toothing with teeth that are directed at an angle to the longitudinal direction L. So are the teeth, how 5A illustrated, with their tooth base directed along line BB. The external toothing 31 is designed in such a way that they are different from the in 5A until 5C Right end face 33 extends towards the other end face 34, the external toothing 31 beginning directly at the end face 33, but running out towards the other end face 34.

What is meant by this is in 5C , depicting a sectional view of a section of the spindle nut 3 along the line BB, based on the course of the tooth base of a tooth of the external toothing 31. The external toothing is divided in the longitudinal direction L into two toothing sections V1, V2, of which one toothing section V1 is formed with a cylindrical toothing and the second toothing section V2 with a toothing with continuously decreasing tooth depth H. In the toothing section V1, the toothing can be formed, for example, with an involute profile, while in the toothing section V2 globoidal toothing with a tooth depth H that decreases towards the end face 34 is provided. The external toothing 31 is formed by radially inward-pointing indentations in a cylindrical lateral surface 32 of a central section of the functional part 7, the tooth depth H being constant in the toothed section V1 and decreasing in the direction of the end face 34 in the toothed section V2.

If the external toothing 31 is designed as a globoidal toothing in the region of the toothing section V2, the tooth base 311 of each tooth in this toothing section V2 is arched with a radius R that is greater than the tooth depth H. The tooth depth H is reduced to zero in this toothing section V2, so that a toothing-free end section 312 adjoins the toothing section V2, which end section 312 delimits the external toothing 31 laterally.

In the region of the toothed section V2, the external toothing 31 can also be designed as a tapered toothing with a radius R which is less than or equal to the maximum tooth depth H. In this case, the tooth base 311 is arched in this toothing section V2, in particular in order to reduce notch stresses at the transition from the (cylindrical) toothing section V1 to the toothing-free end section 312.

Due to the fact that the toothing section V1 extends up to the end face 33, the external toothing 31 is open at the end face 33. This enables the functional part 7 of the spindle nut 3 to be manufactured easily by injection molding. This is because the functional part 7 can easily be removed along the longitudinal direction L from an injection mold for demoulding. This makes it possible to produce the functional part 7 with the external toothing 31 arranged on it in a single operation without using slides to mold the external toothing 31.

By forming the external toothing 31 in sections as globoidal toothing, the strength of the external toothing 31 can also be set up for advantageous power transmission from the drive worm 4 to the spindle nut 3 . Due to the globoidal toothing, the external toothing 31 is at least partially adapted to the toothing 40 (in the form of a worm thread) of the drive worm 4, so that there is an advantageous flat contact between the toothing 40 of the drive worm 4 and the tooth flanks of the external toothing 31 of the spindle nut 3.

In the longitudinal direction L, along which the spindle 1 extends, the vehicle seat is held on the spindle 1 via the adjusting gear 2 . The adjustment gear 2 must therefore be designed in such a way that it can absorb the loading forces, in particular the forces introduced by the adjustment rail 91 in the event of a crash, in a suitable manner in such a way that the vehicle seat is prevented from slipping through in the event of a crash, in order to prevent the vehicle seat from being suddenly adjusted and prevent resulting injuries to a vehicle occupant.

For this reason, the connection of the adjustment mechanism 2 to the upper adjustment rail 91 must have sufficient strength. In addition, the connection should also have a sufficiently high level of rigidity, particularly in the event of a front crash, in order to avoid a forward displacement of a belt connection point holding a seat belt, and to absorb the forces acting in a front crash in a stiff manner. However, in the event of a rear-end collision, too stiff a connection can result in the crash forces acting being transmitted directly to the vehicle occupant and causing the vehicle occupant to move back abruptly, in particular his head. In order to avoid injuries to the vehicle occupant, for example whiplash, it is desirable to at least dampen such a rearward displacement.

6 shows an embodiment of a spindle gear in which a reinforcement part 24 is provided for one-sided support of the adjusting gear 2 relative to the adjusting rail 91, which is designed and provided to absorb forces F acting on the adjusting gear 2 in the longitudinal direction L of the spindle 1 and to support the adjusting gear 2 Force effect in this longitudinal direction L to support. The idea behind such a reinforcement part 24 is to provide one-sided support for the adjusting gear 2 relative to the adjusting rail 91, which achieves the result that Effect of forces in the longitudinal direction L, the adjustment 2 and its connection to the adjustment rail 91 can not deform, so the connection has a high rigidity. The longitudinal direction L corresponds to the longitudinal direction of the vehicle and is directed in the direction of a vehicle driving ahead, so that the forces F arising in a front crash as a result of the inertia of the vehicle seat and a seat occupant are supported via the reinforcement part 24 and the adjusting gear 2 in a front crash in a stiff manner is held.

On the other hand, in the event of an opposing force acting against the longitudinal direction L, the adjusting gear 2 is not supported, so that the adjusting gear 2 can deform at least by a small distance and, in the sense of a crumple zone, the forces acting in a crash are not transmitted directly and rigidly. In the event of a rear-end collision, in which forces act on the adjustment gear 2 in the opposite direction to the longitudinal direction L, the adjustment gear 2 and its connection to the adjustment rail 91 can deform without this being prevented by the reinforcement part 24, so that at least part of the energy in the Crash case is absorbed in the adjusting gear 2 and in its connection.

The use of a reinforcement part 24 is particularly useful in combination with a spindle nut 3 in the form of a hybrid spindle nut, as described above with reference to FIG 3 until 5 portrayed. The spindle nut 3 provides a sufficiently strong connection, even in the event of a crash, so that particularly in the event of a frontal crash, in which the effect of the reinforcement part 24 does not deform the retaining bracket 5 and therefore its legs 51, 52 do not dig into the spindle 1 can engage, the acting crash forces can be dissipated via the spindle nut 3 without the spindle nut 3 slipping through. For this purpose, the spindle nut 3 is supported on the spindle 1 via the strength part 8 so that slipping is prevented.

Advantageously, when using a spindle nut 3 with only one (one-sided) strength part 8, the strength part 8 is arranged on the side of the spindle nut 3 facing the reinforcement part 24.

The reinforcement part 24 embodied, for example, as a cold extruded part is attached to the bracket 5 in the longitudinal direction L behind the adjusting mechanism 2 . The reinforcement part 24 can be pressed onto the mounting bracket 5 or can also be screwed to the mounting bracket 5 and the adjustment rail 91 via a screw connection that extends through the fastening point 58 .

An enlarged, perspective view of the reinforcement part 24 is shown 7 . The reinforcement part 24 has a U-shape in cross section to the longitudinal direction L with two side legs 240 which extend in parallel planes spanned by the longitudinal direction L and a vertical direction S and leave a recess 244 between them through which the spindle 1 in the operative position (see for example 6 ). The legs 240 taper in the opposite direction to the longitudinal direction L and run into a block 242 at the end, which rests against the adjusting rail 91 when the adjusting mechanism 2 is in the assembled state. A reach-through opening 243 is arranged in the center of the reinforcement part 24 and, when the reinforcement part 24 is in the correct position, is flush with the attachment point 58 ( 8th ) and via which the reinforcement part 24 can be connected to the bracket 5 and the adjustment rail 91, for example via a screw connection.

The legs 240 of the reinforcement part 24 form lateral support ribs for supporting forces F acting in the longitudinal direction L. Due to the fact that the legs 240 forming the support ribs extend parallel to the longitudinal direction L and to the vertical direction S, the forces F acting in the longitudinal direction L are introduced in the plane of the legs 240 . Since the mounting bracket 5 rests with its side leg 52 on the reinforcement part 24, the mounting bracket 5 and above it the adjusting gear 2 are supported when forces F are introduced in the longitudinal direction L from the adjusting rail 91 into the adjusting gear 2 and cannot deform, so that a rigid connection of the adjusting mechanism 2 to the adjusting rail 91 is provided. This illustrates 8A : When forces F act in the longitudinal direction L, the bracket 5 cannot deform due to the supporting effect of the reinforcement part 24 . This corresponds to the situation in a front crash, in which a rigid connection of the adjustment gear 2 to the adjustment rail 91 and thus a rigid connection of the rail 92 fixed to the body to the adjustment rail 91 is provided.

In the event of an opposing force in the event of a rear-end crash, in which forces act on the adjustment mechanism 2 counter to the longitudinal direction L, the reinforcing part 24 remains unloaded and does not have a supporting effect on the bracket 5 . this is in 8B illustrates: Forces F' acting against the longitudinal direction L on the adjusting mechanism 2 as a result of the inertia of the vehicle seat and a vehicle occupant in the event of a rear-end crash, see above the bracket 5 can deform in the manner shown by tilting the legs 51, 52.

Since the reinforcement part 24 is arranged behind the adjusting mechanism 2 in the direction of action of the force F', the reinforcement part 24 cannot counteract such a deformation. The upper adjustment rail 91 connected to the bracket 5 and the lower rail 92 fixed to the body, connected to the spindle 1, can thus be offset by an offset V relative to one another. In this case, the adjusting gear 2 and the bracket 5 serve as a kind of crumple zone and absorb part of the crash energy as deformation energy, in order in this way to dampen the forces transmitted to a vehicle occupant and in particular an abrupt rearward displacement of a vehicle occupant in the event of a rear-end crash, which could potentially lead to whiplash.

The idea on which the invention is based is not limited to the exemplary embodiments described above. In particular, an embodiment of a spindle drive with a hybrid spindle nut (with a functional part with external teeth open on one side and tapering off on the other side) in combination with a one-way reinforcing part can be advantageous. The hybrid spindle nut can also reliably absorb large loading forces, so that even in the event of a front crash (with a rigid connection of the adjustment gear to the adjustment rail without a clawing deformation of the bracket), the spindle nut cannot slip and the crash forces are dissipated via the strength part of the spindle nut.

Reference List

1

spindle

10

external thread

11

thrust washer

2

variator

24

reinforcement part

240

leg

242

block

243

access opening

244

recess

3

hybrid spindle nut

30

internal teeth

31

external teeth

310

Tooth base with constant tooth depth

311

Tooth base with decreasing tooth depth

312

End section without toothing

32

Cylindrical lateral surface

33, 34

face

4

drive worm

40

Worm thread of the drive worm

5

bracket

50

base of the bracket

51, 52

side legs of the bracket

53, 54

Through-holes in the lateral legs

55, 56

Bracket mounting flanges

57, 58

Mounting holes of the mounting flanges

6

gear case

61, 62

Housing shells of the gearbox housing

63, 64

Bearing blocks of the gearbox housing

65, 66

Bearing bores of the bearing blocks

67, 68

holes in the housing shells

7

functional part

71

cup-shaped indentation

76

warehouse union

77

spacer ribs

8th

strength part

80

internal teeth

81

cylindrical projection

82

flange

83

cylindrical heel

85

warehouse union

91

adjustment rail

92

Body-mounted rail

A

Distance

f, f'

Power

H

tooth depth

L

longitudinal direction

MA, MI

midplane

R

radius

S

vertical direction

V

offset

V1, V2

gear section

X,Y,Z

length

Claims (23)

Spindle gear, with - a spindle (1) extending in a longitudinal direction (L), - a drive worm (4) of an adjusting gear (2) and - a spindle nut (3) of the adjusting gear (2), which has internal teeth (30) with of the spindle (1) and via an external toothing (31) with the drive worm (4) in engagement in such a way that by driving the drive worm (4) the spindle nut (3) can be set in rotary motion in order to rotate the adjusting gear (2) along the To adjust the spindle (1), the spindle nut (3) being cylindrical in at least one middle section with an outer cylindrical lateral surface (32) and two end faces (33, 34) laterally delimiting the cylindrical lateral surface (32) and the external teeth (31 ) of the spindle nut (3) is formed by radially inward-pointing indentations in the outer cylindrical lateral surface (32) of the spindle nut (3), characterized in that the external toothing (31) extends from the one, first end face (33) along the cylindrical Lateral surface (32) extends in the direction of the other, second end face (34) with a tooth depth (H) which decreases towards the second end face (34), the external toothing (31) being open laterally on the first end face (33), and that the internal toothing (30) of the spindle nut (3) is offset in the longitudinal direction (L) to the external toothing (31) of the spindle nut (3) such that a central plane (MA) of the external toothing (31) running perpendicularly to the longitudinal direction (L) forms a Center plane (MI) of the internal teeth (30) is spaced. Spindle gear after claim 1 , characterized in that the tooth depth (H) decreases continuously or in discrete steps. Spindle gear after claim 1 or 2 , characterized in that the external toothing (31) of the spindle nut (3) has at least two different toothing sections (V1, V2) in the longitudinal direction (L), of which a first toothing section (V1) has a cylindrical toothing with constant tooth depth (H) and a second toothing section (V2) has a non-cylindrical toothing with tooth depth (H) decreasing in the direction of the second end face (34). Spindle gear according to one of the preceding claims, characterized in that the external toothing (31) of the spindle nut (3) is designed at least in sections as globoidal toothing, the teeth of which are adapted to the external toothing of the drive worm (4) and the tooth depth (H) in the direction of the second end face (34) decreases. Spindle gear according to one of the preceding claims, characterized in that the spindle nut (3) has an end section (312) without external teeth on the second end face (34), the tooth depth (H) of the external teeth decreasing in the direction of the end section (312). Spindle gear according to at least one of the preceding claims, characterized in that the external teeth (31) of the spindle nut (3) - as spur teeth whose teeth are directed along the longitudinal direction (L), or - as helical teeth whose teeth are inclined to the longitudinal direction (L ) are directed, is formed. Spindle gear according to at least one of the preceding claims, characterized in that the internal toothing (30) of the spindle nut (3) has a greater length (X) in the longitudinal direction (L) than the external toothing (31) of the spindle nut (3). Spindle gear according to at least one of the preceding claims, characterized in that the spindle nut (3) has a bearing collar (76) formed on the first end face (33) and the internal toothing (30) of the spindle nut (3) extends axially via the external toothing (31) of the spindle nut (3) extends into the bearing collar (76). Spindle gear according to one of the preceding claims, characterized in that the spindle nut (3) is formed by a hybrid spindle nut which has a functional part (7) which is arranged in the power flow between the drive worm (4) and the spindle (1) and forms the functional section, and at least one has a strength part (8) that diverts crash forces from the adjusting rail into the spindle (1). Spindle gear after claim 9 , characterized in that the external toothing (31) of the spindle nut (3) is formed on the functional part (7). Spindle gear after claim 8 or 9 , characterized in that the internal toothing (30) of the spindle nut (3) is formed on the functional part (7). Spindle gear according to one of claims 9 until 11 , characterized in that the strength part (8) of the spindle nut (3) in the longitudinal direction (L) adjoins the second end face (34) of the functional part (7). Spindle gear according to one of claims 9 until 12 , characterized in that the strength part (8) consists of at least one bush forming the end face of the spindle nut (3). Spindle gear according to one of claims 9 until 13 , characterized in that the strength part (8) has an internal toothing (80) whose tooth flanks are spaced apart from the tooth flanks of an external thread (10) of the spindle (1) in such a way that during normal operation of the spindle gear only the internal toothing (30) of the functional part ( 7) engages with the external thread (10) of the spindle (1). Spindle gear according to one of claims 9 until 14 , characterized in that the at least one bushing designed as a strength part (8) is connected to the functional part (7) by gluing or laser welding. Spindle gear according to one of claims 9 until 15 , characterized in that the functional part (7) and the strength part (8) of the spindle nut (3) consist of different materials adapted to the respective strength requirements or have different material proportions adapted to the respective strength requirements. Spindle gear according to one of claims 9 until 16 , characterized in that the strength part (8) of the spindle nut (3) contains a hard metal material, in particular steel, or consists of a hard metal material and at least the internal toothing (30) and the external toothing (31) of the functional part (7) in an engagement area consist of plastic. Spindle gear after Claim 17 , characterized in that the strength part (8) is formed from a hard metal body overmoulded with plastic. Spindle gear after Claim 17 or 18 , characterized in that the functional part (7) consists of a plastic-encapsulated metal material or plastic. Spindle gear according to one of claims 9 until 16 , characterized in that the strength part (8) consists of a high-strength plastic and the functional part (7) consists of a low-strength plastic. Spindle gear according to one of claims 9 until 16 , characterized in that the functional part (7) consists of plastic, which is molded onto the at least one bushing designed as a strength part (8, 8'). Spindle gear according to one of claims 9 until 16 , characterized in that the functional part (7) consists of a hollow-cylindrical body made of a metallic material, in particular steel, with narrow tooth flanks as an internal thread, which is overmoulded with plastic in the area of the internal toothing (30) and in the area of the external toothing (31). . Spindle gear according to one of claims 9 until 16 , characterized in that the functional part (7) of the spindle nut (3) consists of two hollow-cylindrical half-shells made of metal, which are surrounded in the area of the end faces (33, 34) by two sleeves serving as a strength part (8), and that the internal toothing (30) and the outer teeth (31) of the functional part (7) forming plastic is sprayed onto the inner and outer surface of the hollow-cylindrical half-shells.

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