WO2001044009A1

WO2001044009A1 - Adjustable mechanism

Info

Publication number: WO2001044009A1
Application number: PCT/DE1999/003978
Authority: WO
Inventors: Wolfgang Lortz
Original assignee: Wolfgang Lortz
Priority date: 1999-12-13
Filing date: 1999-12-13
Publication date: 2001-06-21

Abstract

The invention relates to an adjustable mechanism, especially for continuously adjusting the inclination of the backrest of a vehicle seat. The mechanism functions according to the principle of a double planetary gear and is comprised of a sun gear (1), planet gears (2) and of two internal gearings (3, 4). The internal gearings (3, 4) have different numbers of teeth. The sun gear (1) is comprised of two toothed wheels (11, 12) that are coupled to one another in a fixed manner. The planet gears (2) are each comprised of two toothed wheels (21, 22) that are coupled to one another in a fixed manner. The center distance and the effective pressure angle between the toothed wheels (21) of the planet gears (2) and the internal gearing (3) and between the toothed wheels (22) of the planet gears (2) and the internal gearing (4) are equal.

Description

variator

The invention relates to an adjustment gear, in particular for the continuous adjustment of the inclination of the back of a vehicle seat, according to the principle of a double planetary gear consisting of a sun gear, planet gears and two internal gears which have different numbers of teeth.

A number of requirements are imposed on adjusting gearboxes for continuously adjusting the inclination of the backrests of vehicle seats. In particular, a sensitive, continuous and play-free adjustment should be possible. In addition, the gears should withstand the forces that occur in the event of a high rear load, for example in the event of a crash with a restraint system integrated into the backrest, and at the same time block the forward displacement of the backrest.

In order to fulfill the tasks it is known from DE-PS 1 2 97 496, for example, to provide two fitting brackets for fine adjustment of backrests, one of which can be pivoted and provided with an internally toothed gear train and the other fitting tab is connected to an externally toothed gear train , The externally toothed gear train runs through eccentric bolts in the internally toothed gear train. A relative displacement of the two mounting brackets is achieved in that the difference in the number of teeth between the internal toothing and the spur gear is one. Blocking in the event of a crash occurs through self-locking. In the known transmission, however, an adjustment of the backrest under load, that is, if the occupant is supported against the backrest, is not possible because the self-locking also blocks a drive position.

DE-PS 30 13 304 represents an extension. Here, the eccentric is divided and adapts flexibly to the load-bearing toothing as a result of a spring force. This avoids overdetermination of the system, which otherwise leads to play or jamming of the backrest adjuster due to manufacturing tolerances. Another construction is known from DE-PS 26 60 395, in which several pins engage in holes in a counter plate. Because of the eccentricity, the holes are larger than the bolts. It is driven by a planetary system. The blocking is also done by self-locking. However, this design has a larger game in the transmission gear, which does not meet the required safety criteria.

In addition, it is known (cf. FR-PS 23 07 495; FR-PS 1 5 66 1 79) to provide a drive with the aid of a sliding block. The sliding block drives a planet gear eccentrically. With this construction, too, blocking in the event of a crash is only caused by friction, which means that adjustment under load is also impossible. In addition, the construction is not able to maintain the selected setting under dynamic load. From DE-PS 26 04 489 the additional provision of a brake is also known. The brake is designed in the form of an elastic element, which serves as a friction brake when loaded from the rear. The adjustment is also carried out via a planetary system. The known construction has the disadvantage that when the sun gear is actuated, part of the torque applied by the brake must be overcome, which leads to stiffness during actuation. In addition, both the construction using a sliding shoe and the construction using an additional brake are technically complex, since a large number of individual parts is required. On the one hand, this leads to an increase in production costs and, on the other hand, an increase in weight. From DE 32 01 309 C2 an adjustment mechanism is also known in which a planetary gear causes the adjustment. The adjustment mechanism has two fitting tabs, in each of which an internal toothing / a ring gear is formed. The internal teeth have different numbers of teeth. The planetary drive runs simultaneously in both internal gears. With this construction, all forces and moments of the meshing teeth are canceled out, which means that the adjustment mechanism is free of forces and moments. It is therefore no longer dependent on the laws of friction, but primarily on the geometrical laws of the flank angle when meshing. In addition, it has only a few components and is therefore inexpensive. However, the known mechanism is not a power transmission. In addition, a "rub" occurs when actuated, that is, the mechanism runs restlessly because the gearing law is violated. Therefore, helical gearing is not possible.

The invention seeks to remedy this. The invention has for its object to provide an adjustment gear, in particular for continuously adjusting the inclination of the backrest of a vehicle seat, which is adjustable under load, runs smoothly and whose blocking does not depend solely on the laws of friction in the case of backward loading of the backrest. According to the invention, this object is achieved in that the sun gear consists of two gears that are firmly coupled to one another and the planet gears each consist of two gears that are firmly coupled with one another, and that the center distance and the operating pressure angle between the gears of the piano wheels and the internal teeth and the gears the planet gears and the internal toothing are the same.

With the invention, an adjustment gear, in particular for the continuous adjustment of the inclination of the backrest of a vehicle seat, which is adjustable under load and at the same time runs cleanly. As a result, the transmission is quiet. In addition, the blocking in the case of high rear load on the backrest does not depend on the friction laws of the teeth. Rather, the circumferential forces on the internal gears are directed in the same amount and in opposite directions. This balance of forces is designed in such a way that the planetary wheels act like “feather keys” in the event of a crash. This ensures the blocking effect in the event of rear loading, as is the case in the event of a crash.

In a further development of the invention, the teeth of the sun gear, planet gears and internal teeth are helical gears. The helical gears are advantageously arranged in opposite directions, so that an arrow gearing results in the view. This configuration ensures that the forces acting on the toothing do not cause any moment, since the horizontal portions of the forces cancel each other out. The internal gears are pressed against each other, which increases the stability of the adjustment gear and makes it impossible to open the two fitting brackets in the event of a crash.

An embodiment of the invention is shown in the drawing and is described in detail below. Show it:

Figure 1 is a perspective view of a vehicle seat with adjustment mechanism. Figure 2 shows the exploded view of an adjustment gear. 3 shows the exploded representation of an adjusting gear in a different design (serration);

4 shows the schematic representation of a DUPLEX adjustment gear; 5 shows a three-dimensional, partial representation of a DUPLEX planetary gear with acting forces with rearward load in a straight-toothed design, and FIG. 6 shows a schematic representation of the flow of force in the event of a crash with arrows.

Toothing.

The vehicle seat shown as an exemplary embodiment in FIG. 1 has a seat surface A. A backrest B is arranged on the seat surface A, the inclination of the seat surface A being infinitely adjustable by means of an adjustment mechanism C. At the end of the backrest B facing away from the seat surface A, a height-adjustable headrest D is provided. The adjustment mechanism C is only schematic in FIG. represented table. It has a handwheel E, with the aid of which the inclination adjustment of the backrest B in relation to the seat surface A is carried out by rotary actuation. For better - symmetrical - force absorption, a further adjustment mechanism F can be attached to the other side of the vehicle seat, which can be actuated by means of a transmission rod G in synchronism with the adjustment mechanism C by means of the handwheel E. The structure of the adjustment mechanism F essentially corresponds to that of the adjustment mechanism C.

The adjustment mechanism C is designed in the form of an adjustment gear. The adjusting gear works on the principle of a double planetary gear (DUPLEX planetary system). It has a sun gear 1, three planet gears 2 and two internal gears 3, 4. The internal gears 3, 4, which can also be referred to as ring gears, are arranged in fitting brackets 5, 6. In the exemplary embodiment, the bracket 5 is mounted on the side of the backrest B, the bracket 6 on the side of the seat A.

The sun gear 1 is arranged against rotation on a shaft (not shown). In the assembled state of the adjusting mechanism, the shaft is connected to the handwheel E shown in FIG. 1. For the case shown in the exemplary embodiment according to FIG. 1, in which, in addition to the adjusting mechanism C, an adjusting mechanism F is also provided on the other side of the seat is, the shaft continues on its side facing away from the handwheel E in the form of the transmission rod G.

The sun gear 1 consists of two gears 1 1, 1 2 which are firmly coupled to one another. The fixed coupling can be achieved in a variety of ways. In the exemplary embodiment according to FIG. 2, the gearwheels 1 1, 1 2 forming the sun gear 1 are coupled to one another in a rotationally secure manner with the aid of four pins 1 3, which pass through both gear wheels 1 1, 1 2. In a modification of the embodiment shown in Figure 2, it is also possible to couple the gears 1 1, 1 2 against rotation without the aid of pins, as shown in the embodiment of Figure 3. For this purpose, welding or soldering or gluing is possible, for example. Also one-piece production is possible, for example by extrusion or injection molding. The gears 1 1, 1 2 each have the same number of teeth. In the exemplary embodiment, twelve teeth are provided on the gears 1 1, 1 2.

Three planet gears 2 circle around the sun gear 1. Each planet gear 2 consists of two gear wheels 21, 22 (DUPLEX system). The gears 21, 22 are also firmly coupled to one another. In the exemplary embodiment according to FIG. 2, the fixed coupling takes place with the aid of pins 23, which are inserted into the gearwheels 21, 22 and enable the fixed coupling. In addition, as with the sun gear 1, the fixed coupling can also take place without pins, as is shown in the exemplary embodiment according to FIG. 3. Here too, the gears 21 can be glued or welded or soldered to the gears 22. One-piece production is also possible. The gears 21 and 22 each have the same number of teeth. In the exemplary embodiment, twelve teeth are provided on each of the gear wheels 21, 22.

The planet gears 2 simultaneously engage in the rotation around the sun gear 1 in the internal gears 3, 4. As can be seen in particular in FIG. 4, the gears 21 engage in the internal gears 3; the gears 22 into the internal toothing 4. The internal toothing 3 and 4 each have different numbers of teeth. In the exemplary embodiment, the internal toothing 3 has thirty-nine teeth, and the internal toothing 4 has thirty-six teeth. The center distance between the gears 21 of the planet gears 2 and the internal teeth 3 and the gears 22 of the sun gears 2 and the internal teeth 4 are the same size. The operating pressure angle α _{w of} the gears 21 of the planet gears 2 with the internal toothing 3 is also the same as the operating pressure angle α _{w of} the gear wheels 22 of the planet gears 2 with the internal toothing 4. The internal gears 3 and 4 are provided in fitting brackets 5 and 6. In the exemplary embodiment according to FIG. 2, the internal toothings 3, 4 are incorporated into the material from which the mounting brackets 5, 6 are made. In the exemplary embodiment according to FIG. 3, the internal toothings 3, 4 are designed in the form of ring gears which are inserted into the fitting brackets 5, 6. To secure against rotation of the internal toothing 3, 4 in the fitting brackets 5, 6, notches in the fitting brackets 5, 6 can be correlated with lugs formed on the ring gears. explosion. Alternatively, a connection is possible, for example by means of laser welding. The fitting tabs 5, 6 are made of sheet metal in the exemplary embodiment. Under certain circumstances, the fitting brackets 5, 6 can also be integrated directly into the backrest cheek or seat connection. Manufacture from other materials is possible.

The planet gears 2 are loosely arranged between the sun gear 1 and the internal gears 3, 4. They are loosely inserted into the internal gears 3, 4 during assembly of the gear and, after assembly, are held by the sun gear 1 and the internal gears 3, 4 in such a way that circling around the sun gear 1 is possible while simultaneously engaging in the internal gears 3, 4. The advantage of this "loose" arrangement of the planet gears 2 in the gearbox is that any distortion that may occur in the mounting brackets 5, 6 does not disturb the tooth geometry, since the piano wheels 2 in principle represent a constant thickness. Therefore, one should under the influence of forces If the normally circular internal gears are deformed towards an oval, the planet gears 2 would “dodge” the deformation, so that a perfect engagement with the sun gear 1 and the internal gears 3, 4 is also ensured in this case.

In order to achieve a blocking of the adjusting mechanism in the event of a crash - that is to say when the seat back is loaded - all circumferential forces between the internal toothing 3 and gear wheels 21 and the internal toothing 4 and gear wheels 22 must be of the same magnitude and in opposite directions. The equilibrium of forces must be designed in such a way that the planet gears 2 which are in engagement with the mounting brackets 5, 6 act like “feather keys”.

With the help of a profile shift, in which the reference profile of the toothing is shifted by an amount with its center line and the reference profile rolls with the generating rolling line on the pitch circle, the operating pressure angle α _w and consequently the direction of force engagement can be influenced. The base circles can be influenced by the generator angle α ₀ . Taking these regularities into account, despite different modules m and different generator angles α ₀ and different profile displacement factors x of the individual planetary systems in the coupled planetary system achieve the same operating pressure angle α _w and thus constant directions of force on the mounting brackets 5, 6. If the operating pressure angles α _{w are} identical, the forces intervene at the same angle. As a result, the circumferential forces in the event of a crash cancel out on the engaging teeth of the gear wheels 21, 22 of the planet gears 2. In this case, the engaging teeth of the planet gears 2 act like feather keys on the circumference of the two fitting brackets 5, 6. The abolition of the forces on the meshing teeth is shown in FIG. 5 for the case of the straight toothing shown in FIG. The forces are specified according to their amount and their direction as well as with their force application points. The illustration makes it clear that the meshing planet gears 2 are only loaded as a result of the normal force F _N. The horizontal proportions of the forces acting in the circumferential direction cancel each other out. The normal force F _N on the three planetary systems cancel each other out on the sun gear. This creates a statically determined system that is irreversible.

In the event of a rearward load, for example in the event of a rear-end collision, the force acting on the seat is introduced into the fitting brackets 5, 6. Since the force is applied from the backrest of the seat to the fitting bracket 5 and this lies outside the longitudinal center line of the adjustment gear, a moment occurs that can lead to the opening of the fitting brackets 5 and 6 to one another. In the worst case, this results in the adjustment mechanism slipping, which means that the backrest can fold forward without resistance. To eliminate this disadvantage, a helical toothing is provided in the embodiment of Figure 3. The gears of sun gear 1, planet gears 2 and internal gears 3, 4 are each helical gears. The helical gearing is oriented in opposite directions with respect to the sun gear 1 from gear 1 1 to gear 1 2, with respect to the planet gears 2 from the gears 21 to 22 and from the internal gearing 3 to the internal gearing 4, so that in principle there is an arrow -Dentangling results (Figures 3 and 6). According to the schematic illustration in FIG. 6, the horizontal portions of the forces parallel to one another are raised by the helical toothing of the individual wheels, which results in an arrow toothing in its entirety Axial direction. In contrast to straight toothing, the tabs are prevented from opening. On the contrary, the horizontal portions of the forces are directed against one another parallel to the axial direction, so that the tabs 5, 6 are pressed against one another and opening is not possible. In the event of a crash, this means that a large part of the energy is used to press the two brackets against each other and the full force applied is not used to shear the gearing (breakage of force).

Claims

claims

1 . Adjustment gear, in particular for continuously adjusting the inclination of the back of a vehicle seat, according to the principle of a double planetary gear consisting of a sun gear (1), planet gears (2) and two internal gears (3, 4), which have different numbers of teeth, characterized in that the sun gear (1) consist of two gears (1 1, 1 2) that are firmly coupled to one another and the planet gears (2) each consist of two gears (21, 22) that are firmly coupled to one another, and that the center distance and the operating pressure angle between the gears (21 ) of the planet gears (2) and the internal teeth (3) and the gears (22) of the planet gears (2) and the internal teeth (4) are the same.

2. Adjustment gear according to claim 1, characterized in that the teeth of the sun gear (1), planet gears (2) and internal gears (3, 4) are each straight gears.

3. Adjustment gear according to claim 1, characterized in that the teeth of the sun gear (1), planet gears (2) and internal gears (3, 4) are each helical gears. Adjusting gear according to claim 3, characterized in that the helical gears are arranged in opposite directions.