Information
-
Patent Grant
-
6267214
-
Patent Number
6,267,214
-
Date Filed
Thursday, December 16, 199924 years ago
-
Date Issued
Tuesday, July 31, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 192 485
- 192 57
- 192 5841
- 192 5842
- 192 104 B
- 192 105 BB
- 192 103 B
-
International Classifications
- F16D3500
- F16D4316
- F16D4706
-
Abstract
A viscous coupling comprising two parts which are supported inside one another, which are rotatable around a common longitudinal axis and which form an annular chamber which is filled with a highly viscous medium and in which there are arranged inner plates which are non-rotatably connected to the inner one of the parts and form a set of inner plates, as well as outer plates which are non-rotatably connected to the outer one of the parts and form a set of outer plates, said inner plates and outer plates being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between the two parts when the latter rotate relative to one another, wherein a partial set of one of the sets of inner plates and outer plates is directly carried by a sleeve which is connected to the part of the coupling which carries said set of inner plates or outer plates in such a way that it can be uncoupled.
Description
BACKGROUND OF THE INVENTION
The invention relates to a coupling, either in the form of an conventional viscous coupling or in the form of a Viscotrac® coupling, comprising two parts which are supported inside one another, which are rotatable around a common longitudinal axis and which form an annular space which is filled with a highly viscous medium and in which there are arranged inner plates which are non-rotatably connected to the inner one of the parts and form a set of inner plates, as well as outer plates which are non-rotatably connected to the outer one of the parts and form a set of outer plates, said inner plates and outer plates being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between the two parts when the latter rotate relative to one another.
In the case of conventional viscous couplings such as those described in DE 38 23 180 C1, the differential-speed-dependent or wheel-slip-dependent engaging effect is based on the build-up of shear forces in the viscous medium in the spaces between inner plates and outer plates.
In the applicant's Viscotrac® coupling described in DE 196 53 310 A1, differential-speed-dependent or wheel-slip-dependent shear forces are built up in the viscous medium in the spaces between inner plates and outer plates in the same way as described above. In addition, in a helical channel between a cylindrical surface of an annular piston dividing the annular space into two chambers and a counter face of the annular space, a medium is conveyed by shear forces from the one chamber into the other chamber, so that the annular piston is axially displaced in the annular space and moves part of the inner plates and outer plates of the coupling plate type into friction contact.
Couplings of said type are used in the driveline of a motor vehicle which comprises both a constantly driven axle and an axle that is driven only if there exists slip between the wheels of the axles, the couplings being provided in the connecting driveline between the two axles.
Under operational conditions, for example, when accelerating from start conditions or during off-highway driving or in curves, when at the constantly driven axle there is wheel-slip, there occurs a relative rotation between the coupling parts, as a result of which a coupling effect is built up, so that the second axle is also driven. In the case of vehicles with new types of driving dynamics systems which, for instance, cause the brake to engage in individual wheels if lateral guidance is lost at the wheels, just as in the case of vehicles with anti-lock braking systems which release the braking force when a wheel is locked, control must be affected only to a slight extent by said coupling engagement. It is therefore the object of the present invention to provide a coupling of the above-mentioned type which is more compatible with control systems for driving dynamics and with anti-lock braking systems of motor vehicles.
BRIEF SUMMARY OF THE INVENTION
The present invention is embodied in and carried out by a coupling of the aforesaid type, wherein in the case of a viscous coupling, the objective is achieved in that a partial set of one of the complete sets of inner plates and outer plates is directly carried by a sleeve which is coupled to that part of the coupling which carries said complete set of inner plates or outer plates in such a way that it will be uncoupled in respect of relative rotation at a raised rotational speed. The corresponding solution in the case of a Viscotrac® coupling consists in that the annular piston is carried directly by a sleeve which is connected to the coupling part carrying the annular piston in such a way that it will be uncoupled therefrom in respect of relative rotation at a raised rotational speed. In particular, it is proposed that a partial set of one of the sets of inner plates and outer plates is also carried directly by the sleeve. The above-mentioned helical channel can be formed by a groove in the cylindrical surface, or in the counter face of the annular space, or optionally in an inserted sleeve.
By using a coupling of this type, it is possible to provide a two-part characteristic curve with a jump function which, in a first portion over the rotational speed follows the characteristics of a viscous coupling or of a Viscotrac® coupling of a certain size and, in a second portion over the rotational speed, represents the characteristics of a viscous coupling with a much smaller number of plates. The latter characteristics are able to provide the comparability with a control system for driving dynamics, a slip limiting control system or an anti-lock braking system. The coupling can be switched from one part of the characteristic curve to the other part of the characteristic curve by any conceivable means, in particular by magnetic, pneumatic or hydraulic means, with the switching process being released by the corresponding control system for driving dynamics or the corresponding anti-lock braking system. All these systems record the vehicle speed and hence the rotational speed of the coupling, which is decisive for the switching process.
According to a preferred simple solution, switching can be effected by a mechanical setting device which is actuated by a centrifugal force and which is integrated into the coupling. In such a case again, it has to be assumed that the rotational speed of the coupling is proportional to the vehicle speed. The setting device actuated by a centrifugal force can comprise circumferentially positioned ball members which, on the one hand, are supported on a first radial face and, on the other hand, on the conical face of an axial adjusting element. The coupling device for the sleeve actuated in this way can, substantially, comprise a central draw key which, in the case of an axial adjustment, causes dwelling balls to engage, or be disengaged from, the respective part of the coupling or of the sleeve in a rotationally positive way. Further preferred embodiments of the invention are described hereunder in further subclaims to which reference is made hereby.
BRIEF DESCRIPTION OF THE DRAWINGS
The written description of the present invention will be more fully understood when read with reference to the accompanying drawings, of which:
FIG. 1
is half a longitudinal section through an inventive coupling in the form of a viscous coupling.
FIG. 2
is half a longitudinal section through an inventive coupling in the form of a Viscotrac® coupling.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1
shows a viscous coupling
11
which substantially consists of a first part
21
in the form of a shaft and a second part
41
in the form of an annular housing which, together, form a cylindrical annular space
31
. The first part
21
comprises a hub
22
and a first sleeve
23
which is non-rotatably connected to the hub
22
by longitudinal toothing means
24
. In addition, the first part
21
carries a second sleeve
25
which, in the direction of rotation, can be coupled with, and uncoupled from, the hub
22
by means yet to be described in greater detail. The first sleeve
23
comprises outer longitudinal toothing means
26
on to which there is slid a first partial set of inner plates
29
. The two sleeves
23
,
25
are sealed relative to one another by a sealing ring
30
.
The second part
41
also consists of several components and comprises two cover parts
42
,
43
which are connected to one another by a casing
44
, with said three parts, together with the sleeves
23
,
25
, forming the annular space
31
. The cover
42
is sealed by a seal
45
relative to the first sleeve
23
, and the cover
43
is sealed by a seal
46
relative to the second sleeve
25
. In the casing part
44
, there are provided inner longitudinal toothing means
47
into which there is non-rotatably inserted a set of outer plates
48
. Individual inner plates
27
,
29
alternate the outer plates
48
in the longitudinal direction. As is usual in the case of a viscous coupling, the annular space
31
is at least partially filled with a highly viscous medium.
The hub
22
is followed by a sleeve projection
32
comprising circumferentially distributed radial bores
33
. The second sleeve
25
is provided with inner grooves or inner recesses
38
which are circumferentially distributed in the same way as the radial bores
33
. Inside the sleeve projection
32
there is provided a draw key
34
with a ramp face
35
and a cylindrical locking face
36
. In each of the bores
33
there are held dwelling balls
37
which, in their position as illustrated, in which they are supported by the locking face
36
, provide a non-rotatable connection for the purpose of coupling the hub
22
with the sleeve
25
. When the draw key
34
is displaced towards the right, the dwelling balls
37
—upon rotation of the sleeve
25
relative to the hub
22
—can be pressed inwardly over the ramp face
35
, so that the hub
22
and the sleeve
25
are uncoupled. When the draw key
34
is pushed back towards the left into the position as illustrated, the dwelling balls
38
are pressed over the ramp faces
35
so that they simultaneously engage radial bores
33
and inner grooves
38
.
The second part
41
, furthermore, comprises a second casing part
49
which is connected to the cover
43
and which, together with a further cover
50
, forms an inner space
51
. The cover
50
is integrally followed by a journal
52
which integrally passes into a flange
53
. In the inner space
51
, there is provided an axial adjusting element comprising a conical cover
62
containing spherical centrifugal weights
63
. The latter are supported on a radial end face
40
of the cover
43
. The conical cover
62
is connected to a journal
64
on to which there is pressed the draw key
34
in the form of a sleeve. The draw key
34
and the journal
64
are non-rotatably coupled relative to one another by a pin
65
.
A helical spring
67
holds the axial adjusting element
61
in the outermost left-hand position as illustrated, with the spring force being sufficient to bias the forces acting on the centrifugal weights
63
. From a certain increased speed onwards, the centrifugal force becomes high enough for displacing the conical cover
62
and thus the journal
64
by means of the outwardly urging centrifugal weights
63
, so that the dwelling balls
37
can reach the region of the ramp faces
35
, with the sleeve
25
being uncoupled from the hub
23
. As a result of the shear forces acting via the second set of inner plates
29
, the sleeve
25
is then taken around by the outer plates
48
, so that it is no longer possible for any torque to be transmitted by the second set of inner plates
29
from the first part
21
to the second part
41
. The coupling function of the first set of inner plates
27
relative to the associated plates
48
is a result of viscous shear forces in the medium between the plates.
FIG. 2
shows a Viscotrac® coupling
111
which substantially consists of a first part
121
in the form of a shaft and a second part in the form of an annular housing which, together, form a cylindrical annular space
131
. The first part
121
comprises a hub
122
and a first sleeve
123
which is non-rotatably connected to the hub
122
by longitudinal toothing means
124
. In addition, the first part
121
carries a second sleeve
125
which, in the direction of rotation, can be coupled with, and uncoupled from, the hub
122
by means yet to be described in greater detail. The first sleeve
123
comprises outer longitudinal toothing means
126
on to which there is slid a first partial set of inner plates
129
. The two sleeves
123
,
125
are sealed relative to one another by a sealing ring
130
. The second part
141
also consists of several components and comprises two cover plates
142
,
143
which are connected to one another by casing part
144
, with said three parts, together with the sleeves
123
,
125
, forming the annular space
131
. The cover
142
is sealed by a seal
145
relative to the first sleeve
123
, and the cover
143
is sealed by a seal
146
relative to the second sleeve
125
. In the casing part
144
, there are provided inner longitudinal toothing means
147
into which there is non-rotatably inserted a set of outer plates
148
.
Individual inner plates
127
,
129
alternate with the outer plates
148
in the longitudinal direction. In the center of the annular space
131
, there is arranged an annular piston
171
which, via driving means
172
, engages the longitudinal outer toothing means
128
of the second sleeve
125
and is thus non-rotatably coupled thereto, but longitudinally displaceable therefrom. The annular piston
171
divides the annular space
131
into two chambers
173
,
175
. The annular piston
171
is surrounded by a sleeve
177
which sleeve, via driving means
178
, engages the inner toothing means
147
in the casing part
144
and is thus non-rotatably coupled thereto. Two securing rings
187
,
188
axially hold the sleeve
177
relative to the casing part
144
. In its inner surface, the sleeve
177
comprises a helical groove
179
which connects the chambers
173
,
175
to one another. In its ends, the annular piston
171
is provided with annular chambers
183
,
185
in which there are positioned compensating pistons
184
,
186
. Directly adjoining the annular piston
171
, there is provided a reinforced pressure disc
174
,
176
in the chambers
173
,
175
. As is common practice with a Viscotrac® coupling, the annular space
131
is filled with a highly viscous medium.
If there occurs a relative rotation between the annular piston
171
and the sleeve
177
, medium is conveyed via the groove
179
from the one chamber into the other chamber and in consequence, the annular piston is displaced in the opposite direction, as a result of which it brings the inner plates and outer plates in said chamber into contact with one another, so that there are generated high braking forces which can lead to the first part
121
and the second part
141
rotating at identical speeds.
The hub
122
is followed by a sleeve projection
132
which comprises circumferentially distributed radial bores
133
. In the second sleeve
125
, there are provided inner grooves or inner recesses
138
which are circumferentially distributed in the same way as the radial bores
133
. Inside the sleeve projection
132
, there is located a draw key
134
with a ramp face
135
and a cylindrical locking face
136
. In the bores
133
there are accommodated dwelling balls
137
which, in the position as illustrated wherein they are supported by the locking face
136
, provide a non-rotatable connection to ensure that the hub
122
and the sleeve
125
are coupled to one another. If the draw key
134
is displaced towards the right, the dwelling balls
137
can be pressed inwardly via the ramp face
135
when the sleeve
125
rotates relative to the hub
122
, so that the hub
122
and the sleeve
125
are uncoupled. When the draw key
134
is moved back towards the left into the position as illustrated, the dwelling balls
137
are pressed back via the ramp face
135
into simultaneous engagement with the bores
133
and the inner grooves
139
.
The second part
141
, furthermore, comprises a second casing part
149
which is connected to the cover
143
and which, together with a further cover
150
, forms an inner space
151
. The cover
150
is radially followed by a journal
152
which integrally changes into a flange
153
. In the inner space
151
, there is provided an axial adjusting element
161
comprising a conical cover
162
in which there are positioned spherical centrifugal weights
163
which are supported on a radial end face
140
of the cover
143
. The conical cover
162
is connected to a journal
164
on to which there is pressed the draw key
134
in the form of a sleeve. The draw key
134
and the journal
164
are non-rotatably connected by a pin
165
.
A helical spring
167
holds the axial adjusting element
161
in the outermost left-hand position, with the spring force being sufficient to bias the forces acting on the centrifugal weights
163
. From a certain increased speed inwards, the centrifugal force becomes sufficiently high to displace the conical cover
162
and thus the journal
164
by means of the outwardly-urging centrifugal weights
163
, so that the dwelling balls
137
are able to reach the region of the ramp face
135
, with the sleeve
125
being uncoupled from the hub
123
. As a result of the shear forces in the groove
179
between the sleeve
177
and the annular piston
171
and between the second set of inner plates
129
and the associated outer plates
148
, the sleeve
125
is then taken around, so that medium is no longer conveyed between the chambers by the annular piston
171
and in consequence, torque is no longer transmitted by the second set of inner plates
129
from the first part
121
to the second part
141
, neither by friction forces as a result of contact between the plates nor by viscous shear forces in the medium between the plates. The coupling function of the first set of inner plates
127
relative to the associated outer plates
148
is a result of viscous shear forces in the medium between the plates.
Certain modifications and variations of the disclosed embodiments of the present invention will be apparent to those skilled in the art. It should be understood that the disclosed embodiments are intended to be illustrative only, and not in any way restrictive of the scope of the invention as defined by the claims set forth hereunder.
Claims
- 1. A viscous coupling (11) comprising inner and outer parts (21, 41) supported inside one another and rotatable relative to one another around a common longitudinal axis, and forming an annular space (31) which is filled with a highly viscous medium in which there are arranged inner plates (27, 29) which are non-rotatably connected to said inner part (21) and form a set of inner plates, as well as outer plates (48) which are non-rotatably connected to said outer part (41) and form a set of outer plates, said inner plates (27, 29) and said outer plates (48) being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between said two parts (21, 41) when the latter rotate relative to one another, wherein a partial set (29) of one of said complete sets of inner plates and outer plates is directly carried by a sleeve (25) which is coupled to the respective one of said inner part (21) and said outer part (41) of the coupling (11), which carries said complete set of inner plates or outer plates in such a way that it can be uncoupled in respect of relative rotation at a raised rotational speed in that it provides a two-part characteristic curve with a declining jump function of coupling forces over rotational speed.
- 2. A Viscotrac® coupling (111) comprising inner and outer parts (121, 141) supported inside one another and rotatable relative to one another around a common longitudinal axis, and forming an annular space (131) which is filled with a highly viscous medium in which there are arranged inner plates (127, 129) which are non-rotatably connected to said inner part (121) and form a set of inner plates, as well as outer plates (148) which are non-rotatably connected to said outer part (141) and form a set of outer plates, said inner plates (127, 129) and outer plates (148) being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between said inner and outer parts (121, 141) when the latter rotate relative to one another, wherein in the annular space (131) an annular piston (171) is arranged axially between said plates to axially divide said annular space (131) into two chambers (173, 175), and is connected to one of said inner part (121) and said outer part (141) by means of driving elements (172) in a non-rotatable and axially movable way, wherein said annular piston (171) by means of one of its cylindrical faces, rests against a counter face of the other one of said inner part (121) and said outer part (141) and wherein, between said one cylindrical face and said counter face, there is formed at least one channel (179) which extends helically relative to the longitudinal axis and which connects said two chambers (173, 175) to one another wherein said annular piston (171) is carried directly by a sleeve (125) which is coupled to that one of said inner part (121) and said outer part (141) of the coupling which carries said annular piston (171) in such a way it can be uncoupled in respect of relative rotation at a raised rotational speed in that it provides a two-part characteristic curve with a declining jump function of coupling forces over rotational speed.
- 3. A coupling according to claim 2, wherein a partial set (129) of said sets of inner plates (127, 129) and outer plates (148) is also directly carried by said sleeve (125).
- 4. A coupling according to claim 2 or 3, wherein said counter face is formed in a sleeve (177) non-rotatably connected to the other one of said inner part (121) and said outer part (141) by means of further driving elements (178).
- 5. A coupling according to any one of claims 1 or 2, wherein a coupling device between said sleeve (25, 125) and said one of said outer part and said outer part (21, 121) consists of a ball locking device actuated by a draw key (34, 134).
- 6. A coupling according to claim 5, wherein said draw key (34, 134) is actuated by an axial adjusting device (61, 161) which, in turn, is actuated by a centrifugal force.
- 7. A coupling according to claim 6, wherein said axial adjusting device (61, 161) comprises ball members (63, 163) which are supported on a fixed radial face (40, 140) and which act on a conical face (62, 162) of a setting member (64, 164).
- 8. A coupling according to any one of claims 1 or 2, wherein said inner plates (27, 29, 127, 129) and said outer plates (48, 148) are axially movably held in said annular space (31, 131).
- 9. An improvement in a viscous coupling which comprises inner and outer parts supported inside one another and rotatable relative to one another around a common longitudinal axis, and forming an annular space which is filled with a highly viscous medium; and a set of inner plates arranged within said annular space and non-rotatably connected to said outer part, and a set of outer plates non-rotatably connected to said outer part, said sets of inner plates and outer plates being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between said inner and outer parts when said inner and outer parts rotate relative to one another, said improvement comprising: a partial set of one of said sets of inner plates and outer plates is directly carried by a sleeve which is coupled to that one of said inner and outer parts which carries said set of inner plates or outer plates in such a way that it can be uncoupled in respect of relative rotation at a raised rotational speed in that it provides a two-part characteristic curve with a declining jump function of coupling forces over rotational speed.
- 10. The improvement according to claim 9, wherein a coupling device between said sleeve and said one of said outer part and said outer part consists of a ball locking device actuated by a draw key.
- 11. The improvement according to claim 10, wherein said draw key is actuated by an axial adjusting device which, in turn, is actuated by a centrifugal force.
- 12. The improvement according to claim 11, wherein said axial adjusting device comprises ball members which are supported on a fixed radial face and which act on a conical face of a setting member.
- 13. The improvement according to any one of claims 9 to 12, wherein said inner plates and said outer plates are axially movably held in said annular space.
- 14. An improvement in a Viscotrac® coupling which comprises inner and outer parts supported inside one another and rotatable relative to one another around a common longitudinal axis, and forming an annular space which is filled with a highly viscous medium; inner plates non-rotatably connected to said inner part and forming a set of inner plates arranged within said annular space; outer plates non-rotatably connected to said outer part and forming a set of outer plates, said inner plates and outer plates being arranged so as to alternate in the longitudinal direction for the purpose of generating a coupling effect between said inner and outer parts when said inner and outer parts rotate relative to one another, wherein in said annular space an annular piston is arranged axially between said plates to axially divide said annular space into two chambers, and is connected to one of said inner and outer parts by means of driving elements in a non-rotatable and axially movable way, wherein said annular piston, by means of one of its cylindrical faces, rests against a counter face of the other one of said inner and outer parts and wherein, between said one cylindrical face and said counter face, there is formed at least one channel which extends helically relative to said longitudinal axis and which connects said two chambers to one another, the improvement comprising: said annular piston is carried directly by a sleeve which is coupled to that one of said inner and outer parts which carries said annular piston in such a way it can be uncoupled in respect of relative rotation at a raised rotational speed in that it provides a two-part characteristic curve with a declining jump function of coupling forces over rotational speed.
- 15. The improvement according to claim 14, wherein a partial set of said sets of inner plates and outer plates is also directly carried by said sleeve.
- 16. The improvement according to claim 14 or 15, wherein said counter face is formed in a sleeve non-rotatably connected to the other one of said inner part and said outer part by means of further driving elements.
- 17. The improvement according to any one of claims 14 or 15, wherein a coupling device between said sleeve and said one of said outer part and said outer part consists of a ball locking device actuated by a draw key.
- 18. The improvement according to claim 17, wherein said draw key is actuated by an axial adjusting device which, in turn, is actuated by a centrifugal force.
- 19. The improvement according to claim 18, wherein said axial adjusting device comprises ball members which are supported on a fixed radial face and which act on a conical face of a setting member.
- 20. The improvement according to any one of claims 14 or 19, wherein said inner plates and said outer plates are axially movably held in said annular space.
Priority Claims (1)
Number |
Date |
Country |
Kind |
198 58 334 |
Dec 1998 |
DE |
|
US Referenced Citations (4)
Number |
Name |
Date |
Kind |
4690258 |
Teraoka et al. |
Sep 1987 |
|
5156247 |
Weise et al. |
Oct 1992 |
|
5273147 |
Beigang et al. |
Dec 1993 |
|
5338266 |
Guimbretiere |
Aug 1994 |
|
Foreign Referenced Citations (5)
Number |
Date |
Country |
3823 180 C1 |
Feb 1990 |
DE |
196 53 310 C1 |
Dec 1996 |
DE |
1-224528 |
May 1987 |
JP |
62-118123 |
May 1987 |
JP |
63-9734 |
Jan 1988 |
JP |