Seat height adjustment device for a vehicle seat, vehicle seat and procedure

Abstract

Seat height adjustment device (4) for adjusting the height of a seat cushion (2) relative to a seat frame (3), in particular an upper rail (3), wherein the seat height adjustment device (4) has an actuating device (5) with a pinion (6) driven by the actuating device (5) and a gear rack (7), the gear rack (7) has a pivot end (8) for linking to the vehicle seat (1) and a front end (9) with a rack section (10) which engages with the pinion (6) for adjusting the pivot end (8) when the pinion (6) is rotated, the gear rack (7) has a reinforced section (12) between the pivot end (8) and the rack section (10), and the reinforced section (12) has a profile.characterized in that the gear rack (7) is hot forged, the front end (9) is hardened by heat treatment after or during hot forging, in the area of ​​the teeth (10a) of the rack area (10) and under martensite formation, and the reinforced area (12) is softer than the material of the rack area (10), wherein the reinforced area (12) is quenched by a heat treatment after or during hot forging, with or without martensite formation.

Description

[0001] The invention relates to a seat height adjustment device for a vehicle seat, a corresponding vehicle seat and a method for manufacturing a gear rack for the seat height adjustment device.

[0002] Seat height adjustment devices generally comprise an actuating device with a pinion driven by the actuating device and a geared rack to adjust a seat cushion. The actuating device can be, for example, an electric motor, but also a manual actuating device, such as a hand lever; the actuating device is, for example, attached to a structural part of the seat cushion and drives the pinion that engages with the geared rack.

[0003] The gear rack has a rack section or row of teeth at one end that engages with the pinion and is thus adjusted longitudinally when the pinion rotates, and a joint at the other end, e.g., with a bearing eye, which is articulated to the seat cushion. The longitudinal adjustment of the gear rack allows the seat cushion to be adjusted relative to the seat frame; depending on the specific swivel mechanism, e.g., by means of rocker arms or couplings, the seat cushion is adjusted in height.

[0004] Accordingly, the gear rack is subject to high loads and is designed as a precision component, especially in the rack area due to the engagement of the pinion, but also in its middle area, which, according to the respective geometry on the vehicle seat, may be bent or curved and thus be subject to bending moments during adjustment.

[0005] For this process, a starting component, generally a flat sheet metal part, is conventionally formed by fine blanking followed by heat treatment for hardening. However, the forming process can generate significant residual stress in the finished part, which can lead to uncontrolled dimensional deviations after heat treatment. Furthermore, the successive manufacturing processes of fine blanking and heat treatment are generally more complex, including logistical, and thus increase overall production costs. Additionally, the punching pull-in that occurs during this manufacturing process is disadvantageous, as it can lead to a loss of load-bearing capacity.

[0006] US Patent 20130040161 A1 describes a method using a tool for manufacturing a component in which a tooth area is formed. The aim is to achieve a uniform wall thickness.

[0007] DE 20 2014 104 538 U1 describes an adjusting element for an adjustment device for adjusting the seat height of a vehicle seat, wherein the adjusting element can be a rocker arm articulated at both ends with a toothed section. The adjusting element has joint mounts for connection to two vehicle seat parts to be adjusted and a toothed section made of hardened material. A coupling section between the joint mounts is designed as a deformation zone for deformation and energy absorption. The toothed section is hardened by heat treatment, e.g., laser treatment, and / or a chemical treatment such as nitriding, whereas the coupling section is unhardened.

[0008] DE 10 2010 009 345 B4 describes a method for manufacturing a component from a thin-walled preform made of metallic material, wherein the component has a support and a circumferential structure which is formed in several forming processes.

[0009] In known systems, the shape of the drive rod is generally determined in a first step, followed by the subsequent shaping and forming. For this purpose, a blank with a suitable shape is generally cut, enabling subsequent cold forming.

[0010] The invention is based on the objective of creating a seat height adjustment device for a vehicle seat that enables the absorption of high forces and adaptation to suitable seat geometries.

[0011] This problem is solved by a seat height adjustment device according to claim 1. Furthermore, a vehicle seat with such a seat height adjustment device is provided, as well as a method for manufacturing the gear rack of the seat height adjustment device.

[0012] Thus, the gear rack, which is driven by the drive pinion or gear pinion at its front end and is articulated at its pivot end to, for example, a structural part of the seat frame, such as an upper rail, is preferably designed as a one-piece, hot-forged component, with a profiled area formed between the pivot end and the rack section. This reinforced, profiled area can be hot-forged to achieve the required stiffness. For example, an H-shape, Z-shape, U-shape, or T-shape can be formed, which particularly allows for higher bending stiffness.

[0013] Thus, the central, reinforced, profiled area of ​​the gear rack between the tooth area and the joint end can form a bent or curved profile, as required or intended according to the respective geometry or position of the joint connection and the mounting of the actuating device, i.e., in particular the electric motor, and yet be designed with relatively little material and high stiffness.

[0014] According to the invention, pre-bending of the component by cold forming is not required; such cold forming generally necessitates prior trimming to prevent cracking in the component, resulting in a bent part that is generally thinner or has lower load-bearing capacity. In contrast, by hot forging the central, reinforced area according to the invention, this area can be bent during the forging process and further profiled to increase its bending stiffness.

[0015] According to the invention, "curved" is understood in particular to mean a non-straight course between the front end and the joint end, i.e. the middle area bulges out in particular compared to a straight connecting line.

[0016] According to the invention, this hot forging process can be combined with a suitable formation of the tooth row or rack section, which is also formed by hot forging. In this process, the starting component can first be pre-cut at its front end, where the tooth row or rack section is to be formed, and then heated so that it is brought to the final contour in a stamping tool, or it can first be heated and then finished in a stamping tool.

[0017] Thus, the entire gear rack can be manufactured in one piece with just a few process steps, whereby a forging process can basically take place along with various work steps in the respective areas.

[0018] The reinforced area can be hardened in particular, i.e. by suitable temperature treatment or quenching, especially under martensite formation.

[0019] Alternatively, the reinforced area can also be specifically designed to be softer and not hardened to absorb crash forces, thus providing a deformation reserve. It can therefore have the appropriate profile to absorb typical bending forces, but be less rigid than the rack and pinion area and, for example, serve to absorb deformation energy in a rear-end collision.

[0020] Thus, the seat height adjustment device according to the invention can also be designed for different positions in vehicle seats or different types of vehicle seats, with a suitable central curved area of ​​the gear rack, which can be reinforced appropriately by profiling.

[0021] The invention is explained below with reference to the accompanying drawings, which illustrate several embodiments. The drawings show: Fig. 1 a gear rack according to an embodiment of the invention; Fig. 2a to Fig. d) further gear racks according to other embodiments, Fig. 3 a vehicle seat with a seat height adjustment device according to an embodiment, with its relevant elements.

[0022] A in Fig. 3 schematically shown vehicle seat 1 a seat cushion, shown schematically here as a structural element 2 on, which is opposite a seat frame with upper rails 3 by means of a seat height adjustment device 4 It is height-adjustable. The seat height adjustment device allows for this. 4 An electric motor is used as an actuating device. 5 on, the one on the seat cushion 2is attached and has a pinion gear with its output shaft 6 drives. A gear rack. 7 is with its joint end 8 e.g. on an upper rail 3 or one with the upper rail 3 connected structural part hinged, with its other end, here called the front end, being the 9 designated, a rack and pinion area 10 is trained to engage with the gear pinion 6 is and therefore when the pinion rotates 6 through the electric motor 5 It is adjusted by operating the electric motor. 5 This will thus be the gearbox rack 7 in their longitudinal direction, which in turn affects the seat cushion 2 adjusted, especially for adjusting the height of the seat cushion 2 .

[0023] The joint end 8 the gearbox rack 7 It is advantageously flat and has a bearing eye.8a on; this is followed by a medium reinforced area. 12 on, which is in the rack area 10 of the front end 9 transitions. The rack and pinion area 10 Its underside has individual teeth 10a up. The gear rack 7 is from its joint end 8 to the rack and pinion area 10 Curved slightly; the precise shape of the middle area 12 is particularly dependent on the geometry at the point of use, i.e., in the vehicle seat 1 dependent.

[0024] Fig. Figure 2 shows further embodiments of such gear racks 7 , each with a joint end 8 with a bearing eye 8a and at its other end 9 a rack and pinion area 10 have a reinforced area between each of them 12is intended as a middle area which can have different profiling depending on the load.

[0025] The gearbox rack 7 It is designed as a one-piece hot-forged component. For its manufacture, a starting sheet metal part is processed in the manner described below; the starting sheet metal part can, for example, be formed directly from a coil, i.e., a strip is drawn from a coil and processed in individual process steps: The reinforced area 12 The shape is formed by hot forging, i.e., deformation in a hot or heated state. This process creates the desired shape or profile, e.g., using the techniques described in... Fig. 2 indicated training programs as H-profile ( Fig. 2a, Fig. 2b), U-profile ( Fig. 2 c)), Z-profile ( Fig.2 d)) or T-profile. Thus, significant stiffening can be achieved solely through this profiling formed during hot forging.

[0026] The front end 9 is preferably used to form the rack and pinion area 10 The tooth row is heated and then cut in this state using a punching tool. During this process, the front end cools. 9 It degrades so quickly that it hardens, advantageously forming martensite. Alternatively, the rack area can be used. 10 It can also be pre-cut to a rough contour and then heated, and in this state the component is brought to its final finished contour in an embossing tool, with appropriate cooling or quenching of the rack area. 10 .

[0027] According to one embodiment, the reinforced area 12The heat treatment during hot forging, i.e., especially rapid cooling after the forging process, also hardens the entire gear rack, i.e., the tooth area. 10 , the joint end 8 and the middle area 10 hardened.

[0028] Alternatively, the middle area can be used 12 It also cannot be hardened. Then preferably the front end. 10 with the rack and pinion area 10 hardened, possibly also the joint end 8 , but not the middle range 10 , which can therefore serve as a deformation reserve, especially in the case of crash deformations.

[0029] As can be seen from the illustrated embodiments, the profiling or deformation is thus entirely or substantially limited to the central reinforced area. 12 limited; the joint end 8is advantageously not profiled. The front end 9 The rack section, as can be seen in the figures, can also be designed without profiling. The rack section 10 can be caused by the formation of teeth 10a which has a greater thickness than the rest of the front end 9 be trained. Reference symbol list 1 vehicle seat 2 seat cushions 3 Upper rail 4 Seat height adjustment device, in particular height adjustment 5 Actuating device, e.g. electric motor 6 pinions, through the actuating device 5 driven 7 Gear rack 8 Joint end 8a Bearing eye of the joint end 9 front end 10 Rack and pinion area at the front end 9 10a Teeth of the rack area 10 12 reinforced area middle area of ​​the gearbox rack 7 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 20130040161 A1

[0006] DE 202014104538 U1

[0007] DE 102010009345 B4

[0008]

Claims

[1] Seat height adjustment device (4) for adjusting the height of a seat cushion (2) relative to a seat frame (3), in particular a top rail (3), wherein the seat height adjustment device (4) has an actuating device (5) with a pinion gear (6) driven by the actuating device (5) and a gear rack (7), the transmission rack (7) has a joint end (8) for linkage to the vehicle seat (1) and a front end (9) with a rack section (10) which engages with the pinion (6) for adjusting the joint end (8) when the pinion (6) is rotated, characterized by , that the gear rack is hot forged, the gear rack (7) has a reinforced area (12) between the joint end (8) and the rack area (10), and the reinforced area (12) has a profile. [2] Seat height adjustment device (4) according to claim 1, characterized by, that the reinforced area (12) is profiled by reshaping its cross-section, in particular in H, U, T or Z shape. [3] Seat height adjustment device (4) according to one of the preceding claims, characterized by , that the front end (9) is hardened by heat treatment after or during hot forging, particularly in the area of ​​the teeth (10a) of the rack area (10), preferably with martensite formation. [4] Seat height adjustment device (4) according to one of the preceding claims, characterized by , that the reinforced area (12) is quenched by a temperature treatment after or during hot forging, preferably with martensite formation. [5] Seat height adjustment device (4) according to one of claims 1 to 3, characterized by , that the reinforced area (12) is softer than the material of the rack area (10), in particular without quenching and / or without martensite formation. [6] Seat height adjustment device (4) according to one of the preceding claims, characterized by , that the gear rack (7) is designed as a one-piece, hot-forged sheet metal part. [7] Seat height adjustment device (4) according to one of the preceding claims, characterized by , that the central reinforced area (12) is bent. [8] Seat height adjustment device (4) according to one of the preceding claims, characterized by , that the actuating device (5) is an electric motor (5) or a manual actuating device, e.g. with a hand lever. [9] Vehicle seat (1) comprising a seat frame (3), a seat cushion (2) which is height-adjustable relative to the seat frame (3) and a seat height adjustment device (4) according to one of the preceding claims. [10] Vehicle seat (1) according to claim 9, characterized by, that the electric motor (5) is attached to the seat cushion (2) and the joint end (8) is articulated to the seat frame (3), preferably to upper rails (3) of the seat frame (3). [11] Method for manufacturing a gear rack (7) for a seat height adjustment device (4) according to any one of claims 1 to 8, comprising at least the following steps: Providing a starting part made of sheet metal, hot forging the starting part under deformation and profiling of its middle area as a reinforced area (12) and under formation of the rack area (10) at its front end (9), wherein the rack area (10) is heated and in this state is finished cut in an existing tool and thereby cooled.

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