U.S. patent application number 10/773648 was filed with the patent office on 2004-10-21 for spindle gear for an adjusting device in a motor vehicle seat.
This patent application is currently assigned to C. Rob. Hammerstein GmbH & Co. KG. Invention is credited to Beneker, Wilfried, Karadag, Arif, Landskron, Robert, Lingner, Michael.
Application Number | 20040206195 10/773648 |
Document ID | / |
Family ID | 32797742 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206195 |
Kind Code |
A1 |
Landskron, Robert ; et
al. |
October 21, 2004 |
Spindle gear for an adjusting device in a motor vehicle seat
Abstract
A spindle gear for a motor vehicle seat adjusting device having
a housing, a spindle nut, a spindle and a worm wheel. The spindle
nut may have an external bearing surface and a bearing shell may
include an internal bearing surface cooperating with the external
bearing surface. The spindle nut may have a slide lacquer coat. The
spindle nut may have an external bearing surface and a stop disk
may be attached to the external bearing surface so as to surround
it. A projection may engage a corresponding spindle nut recess. The
housing may comprise at least two housing parts made of zinc
diecasting. The external teeth of the spindle nut may form a
globoidal gear. The external spindle nut teeth may have an outer
diameter that is smallest in an axial center thereof and increases
toward the axial end regions.
Inventors: |
Landskron, Robert; (Monheim
am Rhein, DE) ; Lingner, Michael; (Dusseldorf,
DE) ; Karadag, Arif; (Solingen, DE) ; Beneker,
Wilfried; (Leichlingen, DE) |
Correspondence
Address: |
AKERMAN SENTERFITT
P.O. BOX 3188
WEST PALM BEACH
FL
33402-3188
US
|
Assignee: |
C. Rob. Hammerstein GmbH & Co.
KG
Solingen
DE
|
Family ID: |
32797742 |
Appl. No.: |
10/773648 |
Filed: |
February 6, 2004 |
Current U.S.
Class: |
74/89.14 |
Current CPC
Class: |
Y10T 74/19828 20150115;
B60N 2/067 20130101; B60N 2/2231 20130101; Y10T 74/18792 20150115;
B60N 2/929 20180201 |
Class at
Publication: |
074/089.14 |
International
Class: |
F16H 027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 24, 2003 |
DE |
103 08 028.7 |
Claims
1. A spindle gear for an adjusting device in a motor vehicle seat,
said spindle gear comprising a spindle having a longitudinally
extending thread, housing, a spindle nut, which is arranged within
the housing, is rotatable within the housing, has an internal
thread matching the thread of the spindle and comprises external
teeth, and a worm wheel that is arranged within the housing, is
rotatable within the housing and comprises of a worm gear that
meshes with the external teeth of the spindle nut, wherein the
spindle gear further comprises at least one of the following
features a) to g): a) that the spindle nut comprises at least one
external bearing surface that is axially offset relative to the
external teeth, that a bearing shell is provided that comprises an
internal bearing surface cooperating with the external bearing
surface, that the bearing shell comprises a slot and that the
bearing shell is inserted within the housing so as to be secured
against torsion; b) that the spindle nut comprises a slide lacquer
coat, said slide lacquer coat being provided on at least one of the
external teeth and on the internal thread; c) that the spindle nut
comprises at least one external bearing surface that is axially
offset relative to the external teeth, that a stop disk is provided
that is attached to said external bearing surface so as to surround
it, that the stop disk has a projection which engages into a
corresponding recess of the spindle nut and forms an antirotation
lock; d) that the spindle nut comprises at least one external
bearing surface that is axially offset relative to the external
teeth, that a stop disk is provided that is attached to said
external bearing surface so as to surround it and that the stop
disk comprises a slide lacquer coat; e) that the housing is
composed of at least two housing parts that are made of zinc
diecasting; f) that the external teeth of the spindle nut are made
as a globoidal gear; and g) that the external teeth of the spindle
nut have an outer diameter that is smallest in the region of the
axial center thereof and that increases toward the axial end
regions thereof.
2. The spindle gear according to claim 1, wherein the outer bearing
surface of the spindle nut is cylindrical and two bearing surfaces
are provided, the external teeth being located between the two
bearing surfaces.
3. The spindle gear according to claim 1, wherein the bearing shell
has an outer border and the housing forms a receiving groove mating
with said outer border.
4. The spindle gear according to claim 1, wherein the bearing shell
forms a radially projecting lug and the housing forms a recess for
receiving said lug.
5. The spindle gear according to claim 1, wherein the external
teeth, as viewed in axial section, have a substantially axially
oriented central contour line having a right side and a left side,
a left curved contour line adjoining on the left side and a right
curved contour line adjoining on the right side, the axial length
of the left curved contour line and the right curved contour line
is greater than the axial length of the central contour line.
6. The spindle gear according to claim 1, wherein the spindle gear
is for a lengthwise adjustment device of a motor vehicle seat.
7. The spindle gear according to claim 1, wherein the spindle gear
further comprises at least two of the features a) to g).
8. The spindle gear according to claim 1, wherein the spindle gear
further comprises at least three of the features a) to g).
9. The spindle gear according to claim 1, wherein the spindle gear
further comprises at least four of the features a) to g).
10. The spindle gear according to claim 1, wherein the spindle gear
further comprises several of the features a) to g).
11. The spindle gear according to claim 1, wherein the spindle gear
further comprises all of the features a) to g).
12. The spindle gear according to claim 1, wherein the projection
engages between two neighboring teeth of the external teeth of the
spindle nut.
13. The spindle gear according to claim 1, wherein the outer
diameter increases from the axial center of the external teeth of
the spindle nut towards the axial regions of the external teeth in
the form of a curve.
Description
[0001] The invention relates to a spindle gear for an adjusting
device in a motor vehicle seat, more specifically for a lengthwise
adjustment device of a motor vehicle seat. The spindle gear has a
housing, a spindle nut, which is rotatably carried within the
housing, has an internal thread matching a longitudinally extending
thread of the spindle and is comprised of external teeth, and a
worm wheel that is rotatably carried within the housing and is
comprised of a worm that meshes with the external teeth of the
spindle nut.
[0002] Spindle gears are successfully utilized in motorized vehicle
seats. They more specifically serve to longitudinally adjust the
motor vehicle seat but may as well be utilized for performing other
adjustment tasks such as reclining adjustment of the seat back,
vertical adjustment of the seat, and so on. The drive thereby uses
an electric motor. Electric motors operate at quite high RPM, the
spindle gear permitting to achieve a very considerable gear
reduction ratio for each line unit. The gear reduction thereby
occurs in two stages. The worm wheel rotates at a RPM speed that
corresponds to the speed of the electric motor. A first
transmission is achieved by the worm gear between the worm wheel
and the external teeth of the spindle nut. In the second
transmission stage mating occurs between spindle nut and spindle,
the latter being provided with a screw thread.
[0003] The spindle thread must be capable of transmitting a certain
torque. If used in a lengthwise adjustment device, the torque
transmitted must be high enough to suffice for the movement of a
person sitting on the motor vehicle seat. The noise level must
thereby remain low. A change in the direction of rotation occurring
for example during switching between fore and aft adjustment is not
allowed to generate a noticeable noise. This must apply to all of
the usually occurring seat loads.
[0004] Finally, the spindle gear must also be capable of taking
impact forces as they occur for example in a frontal crash of a
motor vehicle. Together with the spindle, the spindle gear secures
the longitudinal position of the motor vehicle seat. Here,
sufficient provisions must be made to prevent crash acceleration
from leading to unwanted adjustment of the motor vehicle seat.
[0005] Numerous embodiments of spindle gears have been previously
known in the art and the reader is referred, by way of example
only, to the following documents WO 86-06036 A; DE 41 001 470 C; DE
1755740 A; U.S. Pat. No. 6,260,922 B1; U.S. Pat. No. 5,222,402 and
U.S. Pat. No. 5,349,878.
[0006] In view of these spindle gears, it is the object of the
invention to indicate a particularly smooth running spindle gear
that, accordingly, makes little operating noise under all operating
conditions.
[0007] In view of the spindle gear of the type mentioned herein
above, the solution to this object is achieved in that at least
one, preferably several or all, of the following features are
met:
[0008] that the spindle nut comprises at least one external bearing
surface that is axially offset relative to the external teeth, that
a bearing shell is provided that comprises an internal bearing
surface cooperating with the external bearing surface, that the
bearing shell comprises an axial slot and that the bearing shell is
inserted within the housing so as to be secured against torsion
and/or
[0009] that the spindle nut comprises a slide lacquer coat, said
coat being provided on the external teeth and/or on the internal
thread and/or
[0010] that the spindle nut comprises at least one external bearing
surface that is axially offset relative to the external teeth, that
a stop disk is provided that is placed onto said external bearing
surface so as to surround it, that the stop disk has a projection
(e.g., an axial one) that engages into a corresponding recess of
the spindle nut, more specifically between two teeth of the
external teeth of the spindle nut, and forms an antirotation lock
and/or
[0011] that the spindle nut comprises at least one external bearing
surface that is axially offset relative to the external teeth, that
a stop disk is provided that is attached to said external bearing
surface so as to surround it and that the stop disk comprises a
slide lacquer coat and/or
[0012] that the housing is composed of at least two housing parts
that are made of zinc diecasting and/or
[0013] that the external teeth of the spindle nut are a globoidal
worm gear and/or
[0014] that the external teeth of the spindle nut have an outer
diameter that is smallest in the region of the axial center thereof
and that increases toward the axial end regions, more specifically
in the form of a curve.
[0015] It has been found that each of these features is
advantageous for reducing the operating noise of the spindle gear
around its mounting location within the vehicle seat. Preferably,
all of the features mentioned are implemented although merely
providing the spindle gear with some of the features already proved
advantageous as well. The mere use of but one of the features
indicated already detectably reduces the operating noise.
[0016] The various features mentioned will be discussed herein
after:
[0017] Usually, bearing shells are configured to be annular; now,
it is suggested that the bearing shell be provided with a slot that
is for example oriented radially. Two end faces that are separated
by an air gap are thus formed. Said air gap may vary during
operation. This variation permits to compensate for mechanical
deviations during rotation. The material of the bearing shell
preferably has elastic properties, a metal is used for example.
[0018] Coating the spindle nut with a slide lacquer permits on the
one side to reduce friction between spindle nut and longitudinal
thread of the spindle and on the other side to lower the noise
level. The term slide lacquer coat is to be construed herein as any
lacquer coating such as MoS.sub.2 anti-friction films, MoS.sub.2
lacquers or plastics such as polytetrafluor ethylene (PTFE) or
similar polymers.
[0019] Locking rotation of the stop disk relative to the spindle
nut noticeably lowers the noise level. Now, the stop disk is no
longer a plain washer that somehow moves more or less together with
the nut, it now rotates together with the spindle nut. The locking
of the stop is achieved by an axial projection protruding from the
stop disk and cooperating with the spindle nut, preferably engaging
between neighboring teeth. Thus, the mechanical expense for locking
rotation is extremely low. Kinematic inversion is also possible,
the spindle nut being provided, for this very purpose, with the
projection and the stop disk with a mating recess.
[0020] Coating the stop disk, meaning more specifically the two
radially oriented surfaces, with a slide lacquer coat, leads to an
operating noise reduction.
[0021] Basically, housings that are composed of two or more housing
parts are known. For reducing the operating noise by constructional
design, a housing made of zinc diecasting has proved efficient; it
constitutes an advantageous combination, in particular in
combination with the other features.
[0022] The globoidal engagement of the external teeth of the
spindle nut results in an advantageous smooth meshing and reduces
the operating noise.
[0023] As compared to a mere axial shape, the curved shape of the
spindle nut as viewed in axial section increases the surfaces of
contact with the worm thread of the worm wheel.
[0024] The applicant reserves the right to claim each and every of
the features a)-g) mentioned and any combination thereof.
[0025] Further embodiments of the invention are recited in the
subordinate claims, with only some of them being discussed herein
after.
[0026] Further, it has been found advantageous to non-rotatably
dispose the bearing shell relative to the housing. For this
purpose, the bearing shell has a lug that projects radially and/or
axially, the housing having a mating recess. Kinematic inversion is
also possible, with, in this case, the housing having the lug and
the recess being provided in the bearing shell. Preferably, the lug
is thereby disposed diametrically opposite the slot of the bearing
shell. As a result thereof, the mobility of the bearing shell in
the region of the slot is least affected by the antirotation
lock.
[0027] Eventually, it is advantageous to configure the curved shape
of the external teeth in such a manner that a substantially axially
oriented, short central contour line is provided. Said central
contour line is then adjoined on either side with a curved contour
line. This allows for compensating the tolerances, which again aids
in reducing the noise.
[0028] Further advantages and characteristics of the invention will
become more apparent upon reading the following non restrictive
description of an exemplary embodiment thereof, given with
reference to the drawing in which:
[0029] FIG. 1 is an exploded assembly drawing of a spindle
gear,
[0030] FIG. 2 is a perspective view of the bearing shell as shown
in FIG. 1 and
[0031] FIG. 3 is an axial section through a worm wheel shown in a
modified configuration with respect to FIG. 1.
[0032] The spindle gear has a housing that is composed of a first
housing part 20 and of a second housing part 22. The two parts are
made of zinc diecasting. The two parts 20, 22 are joined together
by riveting. The housing 20, 22 forms an inner volume and bearing
regions for a spindle nut 24 on the one side and for a worm wheel
26 on the other side. In the axial direction, the housing 20, 22 is
open throughout for receiving a spindle 28 that is merely outlined
herein. It has a longitudinal thread 30.
[0033] The spindle nut 24 has an internal thread 32 that meshes
with the longitudinal thread 30 of the spindle 28 and external
teeth 34. In the implementation shown in FIG. 1, the outer lines of
the external teeth 34 lie on a cylinder. On either side of the
external teeth 34, an external bearing surface 36 is formed, said
external bearing surface being cylindrical and having an outer
diameter that is smaller than the outer diameter of the external
teeth 34 at the bottom of the spaces between the teeth, meaning
smaller than the dedendum circle of the teeth 34.
[0034] A flat stop disk 38 is attached to each external bearing
surface 36. It is coated with a slide lacquer, more specifically
with PTFE on its two-main surfaces, preferably allover. It has a
projection 40 which, in the embodiment shown, protrudes axially
although it may as well be configured on a radial axis. In the
assembled condition, said axial projection 40 engages between two
teeth of the external teeth 34, thus providing an antirotation
lock. Said lock may be provided with a certain clearance which may
be adjusted by, for example, adjusting the projection, for example
its dimensions, in the circumferential direction.
[0035] Outside of each stop disk 38, a bearing shell 42 in turn
forms a grip around a respective one of the external bearing
surfaces 36. As compared to the axially relatively thin stop disk
38, the bearing shell has an axial length in the range of several
millimeters, e.g., of 3-6 millimeters. In terms of facts, it
consists of a ring that substantially corresponds to the ring of
the stop disk and of a collar of a smaller outer diameter that is
turned away from the external teeth 34. Together, these two
portions form the inner bore. A lug 44 projects radially from the
collar. On the diametrically opposite side thereof a slot 46 is
formed so that the bearing shell 42, while being made from one
piece, is substantially implemented with the shape of a C. The slot
is provided with small dimensions ranging for example from 0.1 to 2
mm. It provides an air gap 46. In the embodiment shown, the slot is
obtained by a cut that is made in the radial and the axial
direction. The air gap 48 may be defined otherwise as well.
[0036] The bearing shell 42 is made from a metal that has
advantageous slide properties relative to the metal from which the
spindle nut 24 is made. It is also possible to manufacture the
spindle nut 24 from reinforced plastics.
[0037] In the first housing part 20, bearing grooves 50 are
provided for receiving the outer edge of the bearing shell 42. The
housing 20, 22 also comprises a recess receiving the lug 24 so that
the bearing shell 42 is prevented from rotating relative to the
housing 20, 22.
[0038] Further, the worm wheel 26 is carried within the housing 20,
22. Its axis substantially forms a right angle and is offset
relative to the axis of the worm wheel 26 and of the spindle 28. It
has a worm 52 on its outer case and within a polygonal seat for
receiving an elastic drive shaft. At each axial end, the worm wheel
26 is rotatably carried on a ball bearing 56 within the housing 20,
22. Bearing bushes 58 that are similar to the bearing shells 42 are
additionally provided.
[0039] FIG. 3 shows an axial section through a spindle nut 24 that
is modified relative to the implementation shown in FIG. 1. The
lines of the top lands of the external teeth 34 now no longer lie
on a cylinder but on a rotational body that bears certain
similarity to a diabolo or a yarn reel. As shown in FIG. 3, the
external teeth 34 have a substantially axially oriented central
contour line 60 that extends over a quite short axial distance of
for example 0.5-3 mm, preferably of 1.5 mm. It is oriented parallel
to the axis of the spindle nut 34. On either side, said central
contour line 60 is homogeneously and continuously adjoined with a
curved contour line. As a result, the outer diameter of the
external teeth 34 increases steadily, reaching its maximum in the
respective border region of the external teeth 34. The contours 60,
62 may be roughly described as a circle the diameter of which is
greater than the outer diameter of the worm wheel 26. It preferably
may be 1.5-3 times the outer diameter of the worm wheel 26.
[0040] For silencing, two shells 64 made of rubber or of a
corresponding material straddle the gear in a manner well known in
the art, said gear being accommodated in a substantially U-shaped
bearing angle 64.
* * * * *