U.S. patent application number 14/923886 was filed with the patent office on 2017-04-27 for cvt differential.
This patent application is currently assigned to Schaeffler Technologies AG & Co. KG. The applicant listed for this patent is Schaeffler Technologies AG & Co. KG. Invention is credited to Daniel Linton.
Application Number | 20170114871 14/923886 |
Document ID | / |
Family ID | 58561952 |
Filed Date | 2017-04-27 |
United States Patent
Application |
20170114871 |
Kind Code |
A1 |
Linton; Daniel |
April 27, 2017 |
CVT DIFFERENTIAL
Abstract
A CVT (continuously variable transmission) differential is
provided which includes a first drive input ring gear having
internal teeth. A planetary or bevel gear differential is connected
to the first drive input ring gear. The planetary differential
includes a planet gear carrier, first planet gears, second planet
gears, a first sun gear, and a second sun gear. Alternatively, the
bevel gear differential includes a carrier that supports drive and
driven bevel gears. A second drive input is connected to the planet
gear carrier or bevel gear carrier. Preferably, a primary drive is
connected to the first drive input ring gear, which can be an
internal combustion engine or an electric motor. Preferably, a
secondary drive is connected to the second drive input, which is
preferably an electric motor, for example for a hybrid motor
vehicle.
Inventors: |
Linton; Daniel; (North
Canton, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schaeffler Technologies AG & Co. KG |
Herzogenaurach |
|
DE |
|
|
Assignee: |
Schaeffler Technologies AG &
Co. KG
Herzogenaurach
DE
|
Family ID: |
58561952 |
Appl. No.: |
14/923886 |
Filed: |
October 27, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 3/724 20130101;
F16H 3/727 20130101; F16H 48/10 20130101; F16H 48/08 20130101; B60K
6/365 20130101 |
International
Class: |
F16H 3/72 20060101
F16H003/72; F16H 48/08 20060101 F16H048/08; F16H 3/00 20060101
F16H003/00; F16H 48/10 20060101 F16H048/10 |
Claims
1. A continuously variable transmission differential, comprising: a
first drive input ring gear having internal teeth; a planetary
differential connected to the first drive input ring gear, the
planetary differential including a planet gear carrier, first
planet gears, second planet gears, a first sun gear, and a second
sun gear, teeth of the first planet gears are engaged by the
internal teeth of the first drive input ring gear and engage teeth
of the first sun gear, and the teeth of each of the first planet
gears also engage teeth of corresponding ones of the second planet
gears, and the teeth of the second planet gears engage teeth of the
second sun gear; and a second drive input connected to the planet
gear carrier.
2. The continuously variable transmission differential as claimed
in claim 1, further comprising a primary drive connected to the
first drive input ring gear.
3. The continuously variable transmission differential as claimed
in claim 2, wherein primary drive is an internal combustion engine
or an electric motor.
4. The continuously variable transmission differential as claimed
in claim 2, further comprising a torque converter located between
the primary drive and the first drive input ring gear.
5. The continuously variable transmission differential as claimed
in claim 1, further comprising a secondary drive connected to the
second drive input.
6. The continuously variable transmission differential as claimed
in claim 5, wherein the secondary drive comprises a second electric
motor.
7. The continuously variable transmission differential as claimed
in claim 6, wherein the second electric motor is a
motor-generator.
8. The continuously variable transmission differential as claimed
in claim 6, wherein the second electric motor is connected to a
controller in order to control an output ratio of the continuously
variable transmission differential in order to vary at least one of
a speed and a direction of rotation of the first and second sun
gears.
9. The continuously variable transmission differential as claimed
in claim 6, wherein the second electric motor includes a rotor
connected to the planet carrier and a stator that is mounted fixed
relative to the rotor.
10. The continuously variable transmission differential as claimed
in claim 6, wherein the second electric motor includes a drive gear
that engages a gear on the planet carrier.
11. The continuously variable transmission differential as claimed
in claim 1, wherein first and second output shafts are connected to
the first and second sun gears, respectively.
12. The continuously variable transmission differential as claimed
in claim 11, wherein the second drive input comprise a second
electric motor that is arranged concentrically around one of the
output shafts.
13. A combined continuously variable differential, comprising: a
first drive input ring gear having internal teeth; a carrier with
planet gears located within the first drive input ring gear, teeth
of the planet gears engaging the teeth of the first drive input
ring gear; a bevel gear differential including a bevel gear carrier
having external teeth, and the teeth of the planet gears engage the
external teeth of the bevel gear differential; and a second drive
input connected to the carrier.
14. The combined continuously variable transmission differential of
claim 13, further comprising a primary drive connected to the first
drive input ring gear.
15. The combined continuously variable transmission differential of
claim 14, wherein the primary drive comprises an internal
combustion engine or an electric motor.
16. The combined continuously variable transmission differential of
claim 13, further comprising a torque converter located between the
primary drive and the first drive input ring gear.
17. The combined continuously variable transmission differential of
claim 13, wherein the second drive input comprises a gear located
on the carrier, and further comprising a second electric motor
having a second drive gear that engages the gear on the
carrier.
18. The combined continuously variable transmission differential of
claim 17, wherein the second electric motor is a motor-generator.
Description
FIELD OF THE INVENTION
[0001] The present invention is related to the field of drive
trains for motor vehicles, and in particular to continuously
variable transmissions and differentials
BACKGROUND
[0002] Motor vehicles typically include a drive train with a
primary drive, such as an internal combustion engine, which is
paired with a transmission in order to provide different gear drive
ratios from the engine to the drive wheels. Typically, the
transmission is connected to a differential which transmits torque
from the transmission to output axles, with the differential
compensating for different rotational speeds of wheels attached to
the output axles which occurs, for example, during turning. Various
transmissions are known including manual transmissions which
include a vehicle operator activated clutch and a shifter which the
vehicle operator uses to engage different gears, automatic
transmissions which include internal clutches and speed sensors for
automatic shifting between gears, double clutch standard
transmissions which are electronically shifted based on various
operating conditions, as well as continuously variable
transmissions (CVTs) which offer a continuously variable torque
ratio over a wide range of drive ratios without the need for
separate gearing being engaged or disengaged as is required in the
manual, automatic, and double clutch transmissions.
[0003] Differentials are also known in the form of both spur gear
differentials and bevel gear differentials. Spur gear differentials
provide an advantage in that the axial length of the differential
in a direction of the output axes is drastically reduced in
comparison to a bevel gear differential. Spur gear differentials
utilize spur gears connected to a planetary gear carrier that
itself is driven by the transmission output and drives the output
axles via sun gears that engage the planetary gears. Here a first
set of planet gears is associated with the first sun and a second
set of planet gears is associated with the second sun, with the
first and second planet gears also intermeshing via the first set
of planet gears axially overlapping and engaging the second set of
planet gears. The number of teeth of the planet gears of both sets
is equal and the number of teeth of the first and second sun gears
is also equal. Generally, the teeth of the first sun gear are
arranged on a crown circle with a crown circle diameter that is
different than the crown circle diameter of the crown circle on
which the teeth of the second sun are arranged so that the first
set of planet gears meshes with only the first sun and the second
set of planet gears meshes only with the second sun. Such a spur
gear differential is known from U.S. Pat. No. 8,480,532, which is
owned by the assignee of the present invention and is incorporated
herein by reference as if fully set forth.
[0004] Bevel gear differentials also include a carrier in which a
pair of drive bevel gears are mounted that engage with a pair of
driven bevel gears having a common axis that is arranged
perpendicular to the common axis of the drive bevel gears. The
driven bevel gears are connected to the output axles.
[0005] There has been a drive in the automotive field to reduce the
weight of motor vehicles in order to increase efficiency.
Additionally, making portions of the drive train modular for easier
installation and removal of the engine, transmissions and
differential, has also been a consideration in order to reduce
assembly costs. Additionally, further considerations come into play
in connection with hybrid motor vehicles where a primary drive is
provided, generally in a form of an internal combustion engine, and
a secondary drive is provided, typically in the form of an electric
motor driven via on board batteries in the motor vehicle.
[0006] It would be beneficial to reduce the weight of the drive
train of a motor vehicle as well as consolidate components for
easier manufacture and installation in order to reduce
manufacturing costs. Further, it would be desirable to provide a
system that can be easily integrated into hybrid vehicles. It would
also be desirable to eliminate components from a motor vehicle in
order to reduce motor vehicle weight without sacrificing
functionality.
SUMMARY
[0007] A CVT (continuously variable transmission) differential is
provided. The CVT differential includes a first drive input ring
gear having internal teeth. A planetary differential is connected
to the first drive input ring gear. The planetary differential
includes a planet gear carrier, first planet gears, second planet
gears, a first sun gear, and a second sun gear. Teeth of first
planet gears are engaged by the internal teeth of the first drive
input ring gear and engage with teeth of the first sun gear. The
teeth of each of the first planet gears also engage teeth of
corresponding ones of the second planet gears. The teeth of the
second planet gears engage teeth of the second sun gear. A second
drive input is connected to the planet gear carrier. Preferably, a
primary drive is connected to the first drive input ring gear,
which can be an internal combustion engine or an electric motor.
Optionally, a torque converter is located between the primary drive
and the first drive input ring gear. Preferably, a secondary drive
is connected to the second drive input. The secondary drive is
preferably an electric motor, for example for a hybrid motor
vehicle. In this case, it would also be preferable that the second
electric motor is a motor-generator in order to allow regeneration
during braking. The second electric motor is connected to a
controller in order to control an output ratio of the CVT
differential to vary at least one of a speed or a direction of
rotation of the first and second sun gears, which are preferably
connected to output shafts or axles.
[0008] In a preferred embodiment, the second electric motor
includes a rotor connected to the planet carrier and a stator
mounted fixed relative to the rotor, preferably to a vehicle frame
or chassis. Here, the second electric motor is preferably mounted
concentric with the output shaft or axles.
[0009] This arrangement provides a CVT planetary differential that
has an extremely wide gear ratio while maintaining a slim,
lightweight differential design. By providing the internal teeth on
the first drive input ring gear that interact with the planetary
gears, and allowing the planetary carrier to rotate independently
from the first drive input ring gear, and by controlling the
secondary drive in both speed and direction, the output gar ratio
range as well as reverse can be obtained without ever disengaging
the primary gear drive. This provides a compact CVT differential
that eliminates the use of belts, pulleys, tensioners,
synchronizers, as well as a dedicated reverse gear. Further, it is
possible to eliminate a clutch and/or torque converter.
[0010] In another aspect, the CVT differential is formed using a
bevel gear differential. Here the CVT differential includes a first
drive input ring gear having internal teeth. A carrier with planet
gears is located within the first drive input ring gear. Teeth of
the planet gears engage the teeth of the first drive input ring
gear. A bevel gear differential that includes a bevel gear carrier
having external teeth is provided. The teeth of the planet gears
engage the external teeth of the bevel gear differential. A second
drive input is connected to the carrier. This provides a CVT
differential using the known bevel gear differential with
preferably a primary drive being connected to the first drive input
ring gear, with the primary drive being an internal combustion
engine or an electric motor, and a secondary drive, preferably a
second electric motor, being attached to the second drive input.
Optionally, a torque converter is located between the primary drive
and the first drive input ring gear. The second drive input
preferably comprises a gear located on the carrier and further
comprises the second electric motor having a second drive gear
engages the gear on the carrier.
[0011] For hybrid motor vehicles, preferably the second electric
motor is a motor-generator in order to allow regenerative braking.
As in the CVT differential using a spur gear differential, the CVT
differential using a typical bevel gear differential also provides
a combined transmission and differential that eliminates the use of
belts, pulleys, tensioners, synchronizers as well as dedicated
reverse gears and also provides an inherently wide ratio
capability.
[0012] In both cases, the CVT differential designs are ideal for
situations where two power inputs are desired in combination with a
smaller, lighter transmission while maintaining a true differential
torque path to the output axles.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing Summary as well as the following Detailed
Description will be best understood when read in conjunction with
the appended drawings which show a preferred embodiment of the
invention. In the drawings:
[0014] FIG. 1 is a schematic view, in cross section, of a first
embodiment of a CVT differential.
[0015] FIG. 2 is a cross-sectional view through a portion of the
CVT differential shown in FIG. 1 illustrating the first drive input
ring gear driven by an input gear connected to a primary drive as
well as the planetary spur gears connected to a carrier and
engaging sun gears that drive two output shafts, as well as a
second drive input connected to the planet carrier.
[0016] FIG. 3 is an end view, partially in schematic form, showing
the arrangement of the CVT differential in FIG. 2.
[0017] FIG. 4 is a schematic view of a second embodiment of a CVT
differential in which the primary drive and secondary drive are
both electric motors.
[0018] FIG. 5 is a schematic view of a CVT differential as shown in
FIG. 1 connected to a primary drive and a secondary drive.
[0019] FIG. 6 is a schematic view of a third embodiment of a CVT
differential.
[0020] FIG. 7 is a schematic view of a fourth embodiment of a CVT
differential.
[0021] FIG. 8 is a schematic view of a fifth embodiment of a CVT
differential.
[0022] FIG. 9 is a schematic view of a sixth embodiment of a CVT
differential.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] Certain terminology is used in the following description for
convenience only and is not limiting. The words "front," "rear,"
"upper" and "lower" designate directions in the drawings to which
reference is made. The words "inwardly" and "outwardly" refer to
directions toward and away from the parts referenced in the
drawings. These terms and terms of similar import are for ease of
description when referring to the drawings and should not be
considered limiting. "Axially" refers to a direction along the axis
of a shaft or similar object. A reference to a list of items that
are cited as "at least one of a, b, or c" (where a, b, and c
represent the items being listed) means any single one of the items
a, b, or c, or combinations thereof.
[0024] For elements of the invention that are identical or have
identical actions, identical reference symbols are used. The
illustrated embodiments represent merely examples for how the
device according to the invention could be equipped. They do not
represent a conclusive limitation of the invention.
[0025] Referring now to FIG. 1, first embodiment of a continuously
variable transmission (CVT) differential 10 is schematically
illustrated. The CVT differential 10 includes a first drive input
ring gear 12 having external teeth 14 and internal teeth 16. These
are shown in detail FIGS. 2 and 3. The first drive input ring gear
12 is mounted for rotation via bearings, which are not illustrated
in further detail.
[0026] A planetary differential 20 is connected to the first drive
input ring gear 12. The planet differential 20 includes a planet
gear carrier 22, first planet gears 26, second planet gears 27, a
first sun gear 28, and a second sun gear 30. The carrier 22 is
shown in this embodiment as being formed by carrier plates 23a,
23b, that have flanges 24a, 24b, preferably supported via bearings
25a, 25b, as shown in FIG. 2 and FIG. 3. Planet pins 44a, 44b are
used to mount the first planet gears 26 and second planet gears 27
to the carrier 22, as shown in detail in FIG. 2 and represented
schematically in FIG. 1, the first planet gears 26 include teeth 36
that are engaged by the internal teeth 16 of the first drive input
ring gear 12 and also engage teeth 38, of the first sun gear 28.
The teeth 36 of each of the first planet gears 26 also engage teeth
37 of corresponding ones of the second planet gears 27 due to the
axial overlap of the first planet gears 26 with the second planet
gears 27 as shown in detail in FIG. 2. The teeth 37 and the second
planet gears 27 engage teeth 40 and the second sun gear 30. This is
also shown in detail in FIGS. 2 and 3. As shown in detail in FIG.
3, the teeth 36 of the first planet gear 26 have a crown circle
which does not overlap the crown circle of the teeth 40 of the
second sun gear 30.
[0027] As shown in FIGS. 2 and 5, preferably a primary drive 50 is
connected to the first drive input ring gear 12 via a drive gear 55
engaging the external teeth 14 of the first drive input ring gear
12. The primary drive 50 is preferably an internal combustion
engine, but can also be an electric motor. As discussed in detail
below, a torque converter 52 (see FIG. 5) can be located between
the drive 50 and the first drive input ring gear 12.
[0028] Referring to FIGS. 2 and 5, a second drive input 42 is
connected to the planet gear carrier 22 thereby allowing the planet
gear carrier to be both an input from a power source as well as an
integral part of the planetary set. Preferably, a secondary drive
60 is connected to the second drive input 42. In this embodiment,
the secondary drive 60 comprises a second electric motor 62
preferably having a rotor 62R that is fixed to the carrier 22 for
the first and second sets of planet gears 26, 27. The second
electric motor 62 further includes a stator 62S which is mounted to
the chassis or frame, represented as 11. In this embodiment, the
second electric motor 62 is concentric to the output shafts or
axles 68, 70 which are connected to the sun gears 28, 30,
respectively.
[0029] Preferably a motor controller 64 is also provided in order
to control an output ratio of the CVT differential 10 in order to
vary at least one of a speed or a direction of rotation of the
first and second sun gears 28, 30. The second electric motor 62 is
preferably a reversible, brushless DC motor and by varying the
speed of the second electric motor 62, higher or lower output
ratios for the output shaft 68, 70 can be achieved. By reversing a
direction of the second electric motor 62, a direction of rotation
of the output shafts or axles 68, 70 can be reversed, providing a
reverse gear.
[0030] Preferably, the second electric motor is a motor-generator
and a Hall-effect sensor is provided in the second electric motor
62 or in the controller 64 in order to sense a current flow and
switch between a drive mode and a generator mode, depending upon
inputs from the controller 64 which can receive signals from the
ECM or other on board computer for a motor vehicle that provides
various operating parameters as inputs for drive or regeneration to
the second electric motor 62.
[0031] As shown in FIG. 5, the CVT differential 10 in accordance
with the first embodiment is connected to a primary drive 50 which
can be an internal combustion engine or an electric motor and is
fixed to a chassis or frame 11 of the motor vehicle. Here the
torque converter 52 is shown between the primary drive 50 and the
input gear 55.
[0032] Referring now to FIG. 4, a second embodiment of a CVT
differential 10' is shown. The CVT differential 10' is similar to
the CVT differential 10 with respect to the second electric motor
62 as the secondary drive 60. However, the arrangement shown is for
a full electric motor vehicle in which the primary drive 50' is
also an electric motor 51. This primary or first electric motor 51
includes a rotor 51R that is fixed to the first drive input ring
gear 12. The stator 51S of the first electric motor 51 is connected
to the chassis or frame 11 of the vehicle. A controller 53 is
provided for the first electric motor 51. With respect to the
differential arrangement, a spur gear differential 20 is provided
as discussed above. In this case, both the primary drive in the
form of the first electric motor 51 and the secondary drive in the
form of the second electric motor 62 are used to drive the CVT
differential 10'. By varying the speed of either the first or the
second electric motors 51, 62, higher or lower output ratios for
the output shaft 68, 70 can be achieved. By reversing a direction
of the first or second electric motor 51, 62, a direction of
rotation of the output shafts or axles 68, 70 can be reversed,
providing a reverse gear.
[0033] Referring now to FIG. 6, a third embodiment of a CVT
differential 10'' is shown. The CVT differential 10'' utilizes the
spur gear differential 20. As in the first embodiment, and the
primary drive is the internal combustion engine or motor 50
connected to the frame or chassis. This is connected via a torque
converter 52 with the input gear 55. In this case, the secondary
drive input 42 is in the form of a ring gear 43 connected to the
carrier 22. The secondary drive 60 in the form of the electric
motor 61' drives a second input gear 63 that engages with the ring
gear 43 connected to the carrier 22. The controller 64' is shown
connected to the electric motor 61'. Functionally, this provides
the same operation as the first two embodiments with the ability to
change the location of the electric motor 61' rather than having
this arranged concentrically with the output shaft 68, 70.
[0034] Referring now to FIG. 7, a CVT differential 110 is shown.
The CVT differential 110 includes a first drive input ring gear 112
having internal teeth 116 as well as external teeth 114. A carrier
122 with planet gears 126 is located within the first drive input
ring gear 112. Teeth 136 of the planet gears 126 engage the
internal teeth 116 of the first drive input ring gear 112. The
planet gears 126 are preferably mounted via pins 144.
[0035] In this embodiment, a bevel gear differential 180 including
a bevel gear carrier 182 having external teeth 184 is utilized
instead of the spur gear differential. The teeth 136 of the planet
gears 126 engage the external teeth 184 of the bevel gear carrier
182. A second drive input 142 is connected to the carrier 122. In
the embodiment shown in FIG. 7, a primary drive 50 which can be an
engine or an electric motor as discussed above is provided and is
connected to the chassis or frame 11 of the motor vehicle.
Preferably, a torque converter 52 is connected to the primary drive
50 and drives an input gear 55 that engages the external teeth 114
of the first drive input ring gear 112. A secondary drive 160 in
the form of a second electric motor 161 is preferably connected to
the second drive input 142. In this case, the second drive input
142 includes a ring gear 143 and the second electric motor 161
includes a second drive gear 163 that engages with the ring gear
143. Functionally, the CVT differential 110 is identical to the CVT
differential 10'' discussed above with the secondary drive in the
form of the second electric motor 161 providing for a wide gear
ratio without disengaging the primary drive as well as reverse by
changing the direction of the second electric motor 161. The second
electric motor 161 is preferably a reversible, brushless electric
motor with electronic speed control.
[0036] Referring now to FIG. 8, a fifth embodiment of a CVT
differential 110' is shown. The CVT differential 110' is
functionally equivalent to the CVT differential 110 which uses the
bevel gear differential 180 and like elements have been identified
with like numbers. In this case, the bevel gear differential 180 is
offset axially in a direction of the output shafts or axles 68, 70
from the primary drive input with the input gear 55 driving the
carrier 122 that is arranged axially offset from the bevel gear
differential 180. In this case, the bevel gear carrier 182 of the
differential 180 includes external teeth 184' that are offset on
one side of the bevel gear carrier 182. These are engaged by the
planet gears 126 which can be arranged in a reduced pitch circle in
comparison with the embodiment of FIG. 7. This arrangement exhibits
a more compact radial configuration of the components with the same
functionality as discussed above.
[0037] Referring now to FIG. 9, a sixth embodiment of a CVT
differential 110'' is shown. This arrangement is functionally
equivalent to the fifth embodiment 110' except that the bevel gear
differential 180 is nested within a double sided planetary CVT. In
this case, the primary drive via the engine or motor 50 drives a
first drive input ring gear 112'' that includes external teeth
114'' as well as internal teeth 116'' which can be provided as two
separate sets of ring gears 116'' with one located on each side of
the bevel gear differential 180. In this case, the second drive
input 142'' is provided as an external ring gear 143'' on the
carrier 122a. A second carrier 122B is provided for the planet
gears 126 on the opposite side of the bevel gear differential 180.
As shown, the planet gears 126 are rotatably mounted via pins 144A,
144B connected to the respective carriers 122A, 122B. While
functionally identical to the previous embodiment, this arrangement
provides for higher torque transmitting capabilities.
[0038] In each of the above embodiments, all the rotating parts
would be supported via appropriate bearings or bushings and the
arrangements would be encased in an outer casing to allow for
lubrication. As these items are customary in the art, they have not
been described in further detail.
[0039] Having thus described the present invention in detail, it is
to be appreciated and will be apparent to those skilled in the art
that many physical changes, only a few of which are exemplified in
the detailed description of the invention, could be made without
altering the inventive concepts and principles embodied therein. It
is also to be appreciated that numerous embodiments incorporating
only part of the preferred embodiment are possible which do not
alter, with respect to those parts, the inventive concepts and
principles embodied therein. The present embodiment and optional
configurations are therefore to be considered in all respects as
exemplary and/or illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description, and all alternate embodiments and changes to
this embodiment which come within the meaning and range of
equivalency of said claims are therefore to be embraced
therein.
* * * * *