U.S. patent application number 10/635115 was filed with the patent office on 2005-02-10 for smoothly shifting multispeed transmission.
This patent application is currently assigned to New Holland North America, Inc.. Invention is credited to Bulgrien, Garth H..
Application Number | 20050032603 10/635115 |
Document ID | / |
Family ID | 33552930 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050032603 |
Kind Code |
A1 |
Bulgrien, Garth H. |
February 10, 2005 |
SMOOTHLY SHIFTING MULTISPEED TRANSMISSION
Abstract
The apparatus is a 28 speed, two section, transmission that
requires only a single clutch swap for most changeovers between
adjacent ratios. It uses a first section with three close ratio
forward speeds and one reverse along with a second section that is
an 11 speed, wide ratio, transmission. The two transmission
sections are arranged in series resulting at least 28 usable
forward speeds. The second section includes an intermediate
planetary gear set without a ring gear and an output planetary gear
set that is a conventional simple planetary gear set with a two sun
gears, two planes of planetary gears on a single carrier, and two
ring gears.
Inventors: |
Bulgrien, Garth H.;
(Ephrata, PA) |
Correspondence
Address: |
Martin Fruitman
New Holland North America, Inc.
Intellectual Property Dept.
P.O. Box 1895, MS 641
New Holland
PA
17557
US
|
Assignee: |
New Holland North America,
Inc.
New Holland
PA
17557
|
Family ID: |
33552930 |
Appl. No.: |
10/635115 |
Filed: |
August 6, 2003 |
Current U.S.
Class: |
475/302 |
Current CPC
Class: |
F16H 2200/0065 20130101;
F16H 2200/003 20130101; F16H 3/66 20130101; Y10T 74/19233 20150115;
F16H 2003/0818 20130101 |
Class at
Publication: |
475/302 |
International
Class: |
F16H 003/44 |
Claims
What is claimed as new and for which Letters Patent of the United
States are desired to be secured is:
1. A multispeed transmission comprising: a gear set with a first
input, a second input, and an output, arranged so that when the
first input is rotated, and the second input is rotated in the same
direction but at a slower rate than the first input then the output
rotates in the same direction but at a faster rate than the first
input; clutches and associated gears to rotate the second input at
any of at least two fixed ratios of the rate of rotation of the
first input; a clutch to connect the second input to an output
shaft; and a clutch to connect the output to the output shaft.
2. The transmission of claim 1 in which the gear set comprises a
planetary gear set with one carrier and two sun gears, the first
input is one sun gear of the planetary gear set, the second is the
carrier of the planetary gear set, and the output is the other sun
gear of the planetary gear set.
3. (Canceled)
4. (Canceled)
5. (Canceled)
6. The transmission of claim 1 further comprising an input shaft,
dutches, and associated gears to rotate the first input at any of
at least two fixed ratios of the rate of rotation of the input
shaft.
7. The transmission of claim 1 further comprising an additional
clutch and associated gear reduction means arranged to connect the
output to the output shaft through a gear reduction.
8. The transmission of claim 1 further comprising an additional
clutch and associated gear reduction means arranged to connect the
second input to the output shaft through a gear reduction.
9. The transmission of claim 7 further comprising an additional
clutch and associated gear reduction means arranged to connect the
second input to the output shaft through a gear reduction.
10. A multispeed transmission for farm machinery comprising; a
first section connected to and receiving power from an engine, the
first section including an input shaft interconnected with the
engine and at least a first, and a second gear set, each with a
different gear ratio, intersected with the input shaft with each
gear set capable of driving a first intermediate shaft with the
each gear set each controlled by a corresponding clutch, and with
all the clutches driven by the input shaft; a second section
comprising; a second intermediate shaft interconnected with and
driven by the first intermediate shaft, a fourth and a fifth gear
set interconnected with the second intermediate shaft and
controlled by a fourth and fifth clutch, respectively, with the
fourth and fifth gear sets having different gear ratios; an
intermediate planetary gear set with a carrier, an input sun gear,
input planetary gears, an output sun gear, output planetary gears,
and an output shaft attached to the output sun gear, with the
carrier attached to gears of the fourth and fifth gear sets, and
the input sun gear attached to the first intermediate shaft; an
output planetary gear set with a carrier, a first ring gear, a
second ring gear, a first sun gear, a first plane of planetary
gears, a second sun gear, and a second plane of planetary gears,
with the first sun gear attached to the second intermediate shaft
and the second sun gear attached to the output shaft of the
intermediate planetary gear set; a sixth clutch attached to and,
when engaged, braking the first ring gear of the output planetary
gear set; a seventh clutch attached to and, when engaged, braking
the second ring gear of the output planetary gear set; an eighth
clutch attached to the carrier of the output planetary gear set and
to the second intermediate shaft and, when engaged, connecting the
carrier of the output planetary gear set to the second intermediate
shaft; a ninth clutch attached to the carrier of the output
planetary gear set and to the output shaft of the intermediate
planetary gear set and, when engaged, connecting the carrier of the
output planetary gear set to the output shaft of the intermediate
planetary gear set; and a transmission output shaft attached to the
carrier of the output planetary gear set.
11. The transmission of claim 10 further including a reverse clutch
and reverse gearing in the first section so that when the reverse
clutch is engaged, the first intermediate shaft rotates in the
reverse direction from the direction of rotation when any other
clutch in the first section is engaged.
Description
BACKGROUND OF THE INVENTION
[0001] This invention deals generally with mechanical transmissions
and more specifically with a power shift transmission with a large
number of forward ratios and very smooth shifts between gear
ratios.
[0002] Power shift transmissions have been in use for agricultural
tractors for about 40 years. Such transmissions now provide the
capability of shifting through all the forward gears while moving
and while under load without using a clutch pedal. The only action
required by an operator is the selection of the desired gear. The
actual changeover, including the operation of one or more clutches
is electronically controlled and performed by hydraulically powered
clutches.
[0003] In order to provide a wide range of ratios divided into a
large number of small forward ratio steps in a transmission of
practical size and reasonable cost, such transmissions are actually
built as two or three transmissions in a series arrangement. Such a
transmission is disclosed in U.S. Pat. No. 5,036,718 issued to
Bulgrien. However, in such transmissions some of the shifts between
adjacent gear ratios require complex simultaneous changeovers in
two or three of the transmissions. These complex changeovers
frequently result in jerky shifts. Moreover, the tendency to
increase the spread of the overall ratio over the years has
increased the number and severity of these difficult shifts.
[0004] For example, considering only forward speeds, the 18 speed
tractor transmission mentioned above is constructed with an first
section having a three speed transmission with approximately 1.17
ratio steps. The first section is followed by a middle section that
is a three speed transmission with ratio steps of approximately 1.6
and then an output section that is a two speed transmission with a
4.1 ratio step. First gear is achieved by using the lowest ratio in
each of the three transmission sections. Second and third gears are
then achieved by shifting only the input section while leaving the
lowest ratio selected in the middle and output sections. When
shifting from 3.sup.rd to 4.sup.th gear, the middle section is
shifted from its lowest ratio to its intermediate ratio while the
input section is shifted from its highest ratio to its lowest
ratio. This multiple changeover pattern continues through all of
the ratio combinations to yield the 18 different gear ratios.
[0005] However, such a transmission causes discontinuities in the
vehicle motion, the so called jerky shifts, when one or more
sections are being upshifted while another is being shifted down.
Each individual shift involves clutch action that engages one
clutch and gear set and disengages another. Such changeovers are
referred to in the industry as "clutch swaps". The multiple gear
changes are then referred to as "double swaps" and "triple swaps"
as each section of the transmission is shifted by "swapping"
clutches, that is, releasing one clutch and applying another.
Shifting two sections thus involves two clutch changeovers, a
double swap, and shifting all three sections involves three
changeovers, a triple swap.
[0006] The worst condition for the transmission described above
occurs when making the triple swap required to downshift from
10.sup.th to 9.sup.th gear while under load. To accomplish this
shift, the input and middle sections are both shifted from their
lowest ratios to their highest ratios while the output section is
shifted from its high ratio to is low ratio. To make this shift
with minimal change in ground speed would require setting the
pressure in the high ratio clutch in the output section to a level
that is just sufficient to transmit the torque required by the
load, then shifting the input and middle sections to bring up the
speed of the intermediate gears and shafts, then completing the
shift to the low ratio clutch in the output section. To do this the
engine and flywheel would have to momentarily provide enough torque
to pull a 10.sup.th gear load in 18.sup.th gear while the
intermediate gears and shafts accelerate. 18.sup.th gear is about
3.5 times faster than 10.sup.th gear. In fact, the clutches in the
input and middle sections do not have sufficient torque capacity to
do this, and even if they did the loss in engine speed would be
severe. To complete the shift without coming to a complete stop and
without excessive loss of engine speed, the output speed is allowed
to drop rapidly for a brief time while the intermediate gears and
shafts accelerate. It is this action that causes a jerky shift.
[0007] The ratio change in the transmission sections that are
shifted up during an overall downshift is a good indicator of the
difficulty in making shifts involving multiple clutch swaps. In the
transmission described above, the shift from 7.sup.th to 6.sup.th
gear can be made quite smoothly. This shift requires shifting the
input section from its lowest ratio to its highest ratio while
shifting the middle section from its highest ratio to its
intermediate ratio. To make this shift with minimal change in
output speed requires effectively momentarily pulling a 7.sup.th
gear load in 9.sup.th gear. The ratio between 7.sup.th gear and
9.sup.th gear is only about 1.37 compared to the ratio of 3.5
between 1 oth gear and 18.sup.th gear discussed in the example
above, so the downshift from 7.sup.th gear to 6.sup.th gear is much
smoother and less difficult than the shift from 10.sup.th gear to
9.sup.th gear.
[0008] One very beneficial solution would be to have a power shift
transmission in which all shifts between adjacent gears were
accomplished with single clutch swaps as described in U.S. Pat. No.
6,190,280 to Horsch, because this would theoretically provides
smooth shifts going both up and down. However, the Horsch
transmission has rather uneven ratio steps and this condition is
further aggravated if the overall ratio range is increased.
SUMMARY OF THE INVENTION
[0009] The preferred embodiment of the present invention provides a
two section power shift transmission that requires only a single
clutch swap for most changeovers between adjacent ratios, and uses
double swaps for only a few changeovers. No triple swaps are
required. Many of the resulting forward ratios are in near
geometric progression. For example, in the preferred embodiment in
most cases shifting down one speed results in an increase in the
gear ratio of about 13 percent.
[0010] This is accomplished by the use of a first section with
three close ratio forward speeds and one reverse along with a
second output section that is an 11 speed, wide ratio, transmission
section. The two transmission sections are arranged in series
resulting in 33 forward ratios and 11 reverse ratios. Although some
of the ratios produced are nearly duplicates of others, skipping
these duplicate ratios still yields at least 28 usable forward
speeds.
[0011] The invention produces a nearly geometric progression of the
ratios, but, because of the required double clutch swaps for some
of the shifts, with a slight compromise of shift quality. For the
present invention, the most difficult downshifts involve shifting
the 3 speed section up from 1.sup.st to 3.sup.rd while downshifting
the 11 speed section. However, due to the small ratio steps, this
only involves about a 1.28 to 1 speed increase from the input
section. This is a great improvement over all current and previous
power shift transmissions on the market.
[0012] Among the advantages of the present invention are its
elimination of the difficult shifts which have previously been
inherent in all full power shift tractor transmissions and its
small ratio steps that approximately match the smallest ratio steps
currently available. Furthermore, the present invention's 33 ratios
and 28 forward speeds provides a wider overall ratio spread and
more forward speeds than any power shift transmissions currently
available.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic diagram of the transmission of the
preferred embodiment of the invention.
[0014] FIG. 2 is a chart showing the gear sequences and clutch
combinations attainable with the transmission shown in the
schematic diagram of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0015] FIG. 1 is a schematic diagram of transmission 10 of the
preferred embodiment of the invention in which each of the ten
clutches is identified by the designation C1 through C10 located
adjacent to the symbol for the clutch, shafts are identified
adjacent to their symbols, and gears are identified by numerals
preceded by the letter G and identifying lines. It should also be
understood that the clutches are all pictured in a vertical
orientation and labeled near both ends for clarity. On the other
hand, although all gears are also pictured in a vertical
orientation and have two ends, they are typically labeled only
once. The number of teeth in each gear of the preferred embodiment
is indicated by the number adjacent to the symbol representing the
gear in FIG. 1. Furthermore, the relative size relationship of gear
diameters is also shown in FIG. 1. That is, larger gears are shown
larger and smaller gears are shown relatively smaller. Moreover,
where possible, driver and driven gears are shown adjacent to each
other, but where they are not drawn adjacent to each other, their
relationship is explained in the text.
[0016] FIG. 1 is divided into a first section and a second section.
The first section includes input shaft 1, three clutches C1, C2,
and C3 driven directly from input shaft I, clutch 10 for reverse,
several gears driven directly by these clutches, and shaft C. The
second section includes shaft A, clutches C4 and C5 and their
associated gears, planetary gear set 12, planetary gear set 14 and
output shaft O.
[0017] Power from the engine (not shown) is delivered to
transmission 10 at input shaft I, and shaft I also functions as
shaft P, the power takeoff (PTO) shaft. The PTO shaft delivers
power to a conventional hydraulic system (not shown) which
ultimately furnishes the power for the operation of all the
clutches described.
[0018] Input shaft I also is attached to and drives clutches C1,
C2, and C3, and by means of gear G1, it also drives C10 (the
reverse clutch). Selections are made from these clutches to drive
the rest of transmission 10. The operation of FIG. 1 will be more
easily followed by the simultaneous use of the gear sequence chart
of FIG. 2.
[0019] The gear sequence chart of FIG. 2 lists the highest gear
ratio at the top of the chart and the lowest gear ratio at the
bottom, with the entire sequence progressing between the highest
and lowest gears. Lines that are not numbered in the "Gear" column
have small numerals to indicate that these gear ratios are not
recommended for use because they are too close to other ratios
which have been selected. The columns of FIG. 2 are labeled as
noted, and they provide the information indicated below for each
horizontal line.
[0020] Col. "Gear" identifies the gear selection within the
sequence for the line.
[0021] Col. 2 indicates the gear selection within the second
section of the transmission with a number and the gear selection
within the first section with L (low), M (medium), or H (high) for
the line.
[0022] Col. "Ratio" shows the actual gear ratio for the gear
selection.
[0023] Col. "1/Ratio" gives the inverse of the gear ratio, a number
used for design criteria.
[0024] Col. "Clutches" shows the clutches shown in FIG. 1 that are
engaged for the gear selection.
[0025] Col. "Swaps" shows the number of clutch swaps required to
change between the gear selections immediately above and below the
line.
[0026] Col. "Step" indicates the change in ratio between the gear
selections immediately above and below the line.
[0027] Col. "mph" tells the ground speed for the gear selection in
miles per hour.
[0028] Col. "km/h" tells the ground speed for the gear in
kilometers per hour.
[0029] Col. "R step" indicates the change in ratio for reverse
speeds.
[0030] Col. "R mph" tells the ground speed in reverse in miles per
hour.
[0031] Col. "R km/h" tells the ground speed in reverse in
kilometers per hour.
[0032] It should be noted that, for reverse speeds in the chart of
FIG. 2, gear selections for ground speeds over 12 mph and one lower
speed at gear selection 12 are not actually used, although they are
theoretically available. As with the other unused gear selections,
these lines are printed with smaller numerals.
[0033] Several gear selections are described below with reference
to FIG. 1, beginning with gear selection 1, at the bottom line of
FIG. 2.
[0034] Gear selection 1 produces a ground speed of only 1.33 mph,
and for it clutches C1, C4, and C6 are engaged. Clutch C1 is
connected to gear G1 that is permanently attached to input shaft I
so that gear G1 is constantly rotating. The engagement of clutch C1
causes gear G2 to rotate, and gear G2 drives gear G3 that is
attached to shaft C. Shaft C then drives shaft A through gears G4
and G5. In fact, gears G4 and G5 always drive shaft A from shaft C
so that the speed of shaft A is determined by the selection of
either clutch C1, C2, C3, or C10 (reverse) that interconnect shaft
I to shaft C with different size gears.
[0035] Therefore, there are three forward and one reverse speed
choices available between shaft I and shaft C. There are three
forward gear combinations, G2 to G3, G6 to G4, and G7 to G8 that
connect shaft I and shaft C depending upon the selection of
clutches C1, C2, or C3. In the preferred embodiment of the
invention, theses gear combinations are designed to yield gear
ratio steps of 1.13 as the engaged clutch is sequenced from C1 to
C2 to C3.
[0036] For clarification, it should be understood that gear G15,
which is the gear powered from reverse clutch C10, actually engages
gear G3, although they are not shown in contact in FIG. 1. Reverse
clutch thereby also interconnects shaft I with shaft C, but, of
course, with reverse rotation.
[0037] Clutches C4 and C5 then provide the choice of two gear sets
with different ratios, G9 to G10 and G11 to G12, by which to drive
planetary gear carrier CR1 and sun gear G20 from shaft A. For gear
selection 1 of FIG. 2, clutch C4 is engaged to rotate sun gear G20.
In gear selection 1 of FIG. 2, clutch C6 is also engaged. This
stops ring gear RG1 of output planetary gear set 14 and causes
output carrier CR2 to rotate at a slower rate than sun gear G20.
Output shaft O, which is attached to output carrier CR2 is thereby
driven from shaft A through the planetary reduction of output
planetary gear set 14.
[0038] It should be understood that intermediate planetary gear set
12 is constructed without a ring gear to accomplish its required
operation while output planetary gear set 14 consists of two
conventional simple planetary gear sets with two sun gears, two
planes of planetary gears mounted on a single carrier, and two ring
gears.
[0039] The three lowest gear selections of FIG. 2 are accomplished
by merely swapping through clutches C1, C2, and C3.
[0040] Another example taken from FIG. 2 is the series of steps
from gear selection 16 through gear selection 24. This sequence
starts at gear selection 16 with clutches C1, C4, and C8 engaged.
Clutch C8 directly connects output carrier CR2 and output shaft O
to intermediate carrier CR1, so that clutch C1 and C4 determine the
speed of output shaft O. Gear selections 17 and 18 then swap clutch
C1 to C2 and then to C3, thus increasing the gear ratio by 1.13
with each step.
[0041] For gear selection 19 there is a double swap when clutch C3
is exchanged for clutch C1 for a lower gear ratio while clutch C4
is exchanged for clutch C5 for a higher gear ratio. The net change
in ratio with these two swaps is 1.13, essentially the same as the
last two steps. The next two gear selections merely require once
more moving from clutch C1 to clutches C2 and C3, each with a ratio
change of 1.13.
[0042] Then for gear selection 22, there is another double swap.
Clutch C3 is again exchanged for clutch C1 and clutch 5 is
exchanged for clutch C9. Here again the net ratio change is
1.13.
[0043] With both clutches C8 and C9 engaged and neither C4 nor C5
engaged, output shaft O is locked onto sun gear G21 and sun gear
G20 of the output planetary gear set. This causes the intermediate
carrier and sun gear G17 to rotate at the same speed, thus forcing
intermediate planetary gear set 12 to rotate as a unit. The result
is that shaft C and output shaft O rotate at the same speed. Once
again, the next two gear selections merely require moving from
clutch C1 to clutch C2 and then to C3, each with a ratio change of
1.13.
[0044] With only a few exceptions, FIG. 2 shows that the entire
sequence of gears is accomplished by selecting one of the 11
available gear ratios in the second section and then stepping
through the three forward gear selections in the first section.
[0045] The second section includes a two speed gear section with
clutches C4 and C5 providing a 1.28 ratio change between their gear
sets, an intermediate planetary gear set without a ring gear but
with input and output sun gears, and an output simple planetary
gear set.
[0046] The two speed gear section includes clutches C4 and C5 that
provide the choice of two gear sets with different ratios, G9 to
G10 and G11 to G12. Both of these gear sets are attached to
planetary gear carrier CR1. Thus, by the selection of either clutch
C4 or clutch C5, the speed of carrier CR1 can be changed relative
to the speed of shaft A.
[0047] Inverting planetary gear set 12 provides a ratio inverting
function that provides the means for making shifts between any
adjacent ratios in the 11 speed second section with a single clutch
swap. Shaft C is connected to input sun gear G14 to provide a
reaction member rotating at a reference speed. When C5 is engaged,
G12 drives G20 at a lower rotational speed than shaft C, but
inverting planetary gear set 12 causes G21 to rotate at a higher
rotational speed than shaft C. As the rotational speed of the
inverting carrier is reduced relative to shaft C, the rotational
speed of G17 and G21 are proportionally increased relative to shaft
C. Thus, when G20 is driving the output shaft, shifting from C4 to
C5 causes the rotational speed of the output shaft to increase, but
when G21 is driving the output shaft, shifting from C5 to C4 causes
the rotational speed of the output shaft to increase.
[0048] Output planetary gear set 14 adds still more gear ratios
possibilities. One is that clutch C9 permits carrier CR2 and output
shaft O to be connected directly to output sun gear G17 of
inverting planetary gear set 12 by means of shaft E. Another is
that clutch C8 can connect carrier CR2 and output shaft O directly
to carrier CR1 of inverting planetary gear set 12. Furthermore,
when both clutches C8 and C9 are engaged, output shaft O and both
carriers CR1 and CR2 are attached to shaft C.
[0049] Moreover, clutches C6 and C7 can brake their respective ring
gears RG1 and RG2 to transmit rotation to carrier CR2. When clutch
C6 is engaged carrier CR2 is driven through the gear reduction of
output planetary gear set 14 through its sun gear G20, and when
clutch C7 is engaged carrier CR2 is driven from shaft E through the
gear reduction of output planetary gear set 14 through its sun gear
G21.
[0050] As disclosed in FIG. 2, these multiple variations in the
gear ratios within the second section of the transmission along
with the three forward and one reverse ratio available from the
first section of the transmission give the preferred embodiment of
the invention the ability to furnish 28 distinct speed
variations.
[0051] It is to be understood that the form of this invention as
shown is merely a preferred embodiment. Various changes may be made
in the function and arrangement of parts; equivalent means may be
substituted for those illustrated and described; and certain
features may be used independently from others without departing
from the spirit and scope of the invention as defined in the
following claims.
[0052] For example, bevel gears can also be used within inverting
planetary gear set 12, and different configurations of planetary
gear systems, such as the use of a ring gear to replace one sun
gear in planetary gear set 12, can be used to accomplish the same
results.
* * * * *