GB2309755A - Three speed automatic transmission allows ratio change by the operation of a single clutch - Google Patents
Three speed automatic transmission allows ratio change by the operation of a single clutch Download PDFInfo
- Publication number
- GB2309755A GB2309755A GB9602272A GB9602272A GB2309755A GB 2309755 A GB2309755 A GB 2309755A GB 9602272 A GB9602272 A GB 9602272A GB 9602272 A GB9602272 A GB 9602272A GB 2309755 A GB2309755 A GB 2309755A
- Authority
- GB
- United Kingdom
- Prior art keywords
- planetary gear
- gear
- input
- clutch
- automatic transmission
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H3/00—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion
- F16H3/44—Toothed gearings for conveying rotary motion with variable gear ratio or for reversing rotary motion using gears having orbital motion
- F16H3/62—Gearings having three or more central gears
- F16H3/66—Gearings having three or more central gears composed of a number of gear trains without drive passing from one train to another
- F16H3/666—Gearings having three or more central gears composed of a number of gear trains without drive passing from one train to another with compound planetary gear units, e.g. two intermeshing orbital gears
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H2200/00—Transmissions for multiple ratios
- F16H2200/20—Transmissions using gears with orbital motion
- F16H2200/2002—Transmissions using gears with orbital motion characterised by the number of sets of orbital gears
- F16H2200/2007—Transmissions using gears with orbital motion characterised by the number of sets of orbital gears with two sets of orbital gears
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Structure Of Transmissions (AREA)
Abstract
An automatic transmission (10) comprising a housing (12); a planetary gear train (14) mounted within the housing; an input drive shaft (16) for providing input drive to the planetary gear train; an output drive shaft (18) connected with an output drive (32) from the planetary gear train; a first clutch (C1) connected between the input drive shaft and a first drive input (22) to the planetary gear train; a second brake (C2) acting on a first reaction input (28) to the planetary gear train; and a third clutch (C3) connected between a second drive input (24) to the planetary gear train and the input drive shaft; wherein for first forward gear ratio the first clutch is engaged; for second forward gear ratio the first clutch and the second brake are engaged; and for third forward gear ratio the first and third clutches and the second brake are engaged. Allows gear shift by the operation of a single clutch.
Description
AUTOMATIC TRANSMISSION
The present invention relates to an automatic transmission having three or more forward speed ratios.
Automatic transmissions are known in which the operation of a planetary gear train is controlled to provide the desired output gear ratio. In these known arrangements, a number of friction devices, that is, clutches and brakes, are engaged and disengaged to control the relative rotation of the gears of the planetary gear train to provide the required gear ratio.
A problem with known arrangements is the necessity to control the timing of the disengagement of a clutch or brake whilst substantially simultaneously engaging another clutch or brake to provide a change from one gear ratio to another gear ratio.
It is an object of the present invention to overcome this problem.
An automatic transmission in accordance with the present invention comprises a housing; a planetary gear train mounted within the housing; an input drive shaft for providing input drive to the planetary gear train; an output drive shaft connected with an output drive from the planetary gear train; a first clutch.
connected between the input drive shaft and a first drive input to the planetary gear train; a second clutch connected between a first reaction input to the planetary gear train and the housing; and a third clutch connected between a second drive input to the planetary gear train and the input drive shaft; wherein for first forward gear ratio the first clutch is engaged for second forward gear ratio the first and second clutches are engaged; and for third forward gear ratio the first, second and third clutches are engaged.
In the present invention, therefore, a gear change or shift between adjacent forward ratios is achieved by the engagement or disengagement of a single clutch, thereby eliminating the need for a timed engagement and disengagement of two or more friction elements.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a schematic diagram of an automatic transmission in accordance with the present invention;
Figure 2 is a schematic side view of the first planetary gear set of the planetary gear train of the automatic transmission of Figure 1;
Figure 3 is a schematic side view of the second planetary gear set of the planetary gear train of the automatic transmission of Figure 1; and
Figure 4 is a table of gear ratio and clutch engagement for the automatic transmission of Figure 1.
Referring to Figure 1, an automatic transmission 10 in accordance with the present invention is shown. The transmission 10 is capable of providing four forward speed ratios and one reverse speed ratio.
The automatic transmission 10 comprises a housing 12, a planetary gear train 14, an input drive shaft 16 and an output drive shaft 18. The input drive shaft 16 is connectable with the output drive shaft of an engine or other powered driving means (not shown), preferably by way of a torque converter (not shown), in any suitable manner known to those skilled in the art. The output drive shaft 18 is connected to the driven wheels (not shown) of a motor vehicle or other rotatably driven means in any suitable manner known to those skilled in the art. The planetary gear train 14 comprises a pair of planetary gear sets 40,42 each comprising a sun gear 44,46, respectively, and a ring gear 48,50, respectively.The first planetary gear set 40 further comprises first and second pinion gears 52,54, respectively, interengaging the sun gear 44 and the ring gear 48, the pinion gears being rotatably mounted on a common planet carrier 56 which can also rotate. The layout of the sun gear 44, ring gear 48 and pinion gears 52,54 can be seen in Figure 2. The second planetary gear set 42 further comprises a pinion gear 58 interengaging the sun gear 46 and the ring gear 50, the pinion gear being rotatably mounted on a planet carrier 60 which can also rotate. The layout of the sun gear 46, ring gear 50 and pinion gears 58 can be seen in
Figure 3. The sun gears 44,46 and the ring gears 48,50 have a common centre line R (axis of rotation) which is parallel to the centre line (rotational axes) of the pinion gears 52,54,58 and the centre line (rotational axes) of the planet carriers 56,60.The planet carrier 56 of the first planetary gear set 40 is connected to the sun gear 46 of the second planetary gear set 42.
The sun gear 44 of the first planetary gear set 40 is connected to the ring gear 50 of the second planetary gear set 42. The planet carrier 60 of the second planetary gear set 42 drives the output shaft 18.
Additional identical sets of pinion gears 52,54,58 may be positioned between the sun gears 44,46 and the ring gears 48,50.
The planetary gear train 14 has first, second and third drive inputs 22,24,26, respectively, connectable with the input drive shaft 16. The planetary gear train 14 also has first and second reaction inputs 28,30, respectively, connectable with the housing 12. The first drive input 22 is connected with the sun gear 44 of the first planetary gear set 40 and the ring gear 50 of the second planetary gear set 42. The second drive input 24 is connected with the ring gear 48 of the first planetary gear set 40. The third drive input 26 is connected with the planet carrier 56 of the first planetary gear set 40 and the sun gear 46 of the second planetary gear set 42. The first reaction input 28 is connected with the planet carrier 56 of the first planetary gear set 40 and the sun gear 46 of the second planetary gear set 42.The second reaction input 30 is connected with the ring gear 48 of the first planetary gear set 40. The first drive input 22 is connectable with the input drive shaft 16 by way of a first clutch Cl and a first free wheel or oneway coupling Fl. The first reaction input 28 is connectable with the housing 12 by way of a second clutch C2 and a second free wheel or one-way coupling
F2. The second drive input 24 is connectable with the input drive shaft 16 by way of a third clutch C3. The first reaction input 28 is also connectable with the housing 12 by way of a fourth clutch C4. A fifth clutch C5 is connected in parallel with the first clutch C1 and one-way coupling F1 between the first drive input 22 and the input drive shaft 16.The third drive input 26 is connectable with the input drive shaft 16 by way of a sixth clutch C6. The second reaction input 30 is connected with the second drive input 24 and is connectable with the housing 12 by way of a third free wheel or one-way coupling F3 or by way of a seventh clutch C7.
Referring to Figure 4, the automatic transmission 10 is capable of providing a first forward gear ratio, a second forward gear ratio which is less than the first ratio, a third forward gear ratio which is less than the second ratio, a fourth forward gear ratio which is less than the third ratio, and a reverse gear ratio. The third ratio is direct drive, and the fourth ratio is an overdrive.
For first forward gear ratio operation, first and fifth clutches C1 and C5 are engaged (applied) and first and third one-way couplings F1 and F3 are also engaged (under load). The other clutches remain disengaged and the other one-way coupling acts as an over-running free wheel. For second forward gear ratio operation, first, second, and fifth clutches C1, C2 and C5 are engaged and first and second one-way couplings F1 and F2 are also engaged. For third forward gear ratio operation, first, second, third and fifth clutches C1,
C2, C3 and C5 are engaged and first one-way coupling F1 is also engaged.For fourth forward gear ratio operation, first, second, third and fourth clutches C1,
C2, C3 and C4 are engaged. For reverse gear ratio, sixth and seventh clutches C6 and C7 are engaged.
In first, second and third forward gear ratios, fifth clutch C5 is applied to overrun the first one-way coupling F1 in order to provide engine braking.
The shift from third forward gear ratio to fourth forward gear ratio is achieved by engaging (applying) fourth clutch C4 and disengaging (releasing) fifth clutch C5. However, fifth clutch C5 can be released/applied approximately one second before/after fourth clutch C4 is applied and so there is no need for complex time control of the operation of these clutches
C4, C5.
It will be appreciated, therefore, that a shift from first forward gear ratio to second forward gear ratio is achieved by engaging (applying) second clutch C2. Similarly, a shift from second forward gear ratio to third forward gear ratio is achieved by engaging (applying) third clutch C3, and a shift from third forward gear ratio to fourth forward gear ratio is achieved by engaging (applying) fourth clutch C4. All of these shifts can be achieved without the need for complex time control of the operation of the clutches.
The ratios of the four forward gears are calculated as shown in Figure 4. kl is a constant in which
kl = dl / al where dl is the number of teeth on the ring gear 48 of the first planetary gear set 40 and al is the number of teeth on the sun gear 44 of the first planetary gear set 40. k2 is a constant in which
k2 = d2 / a2 where d2 is the number of teeth on the ring gear 50 of the second planetary gear set 42 and a2 is the number of teeth on the sun gear 46 of the second planetary gear set 42.
In the present invention, shifts from one ratio to another can be achieved solely by operating only one clutch, removing the need for timing control of engaging/disengaging clutches, thereby providing quieter and more reliable gear shifts. Further, in the overdrive ratio (fourth forward gear ratio), the ratio can be made greater than or equal to 0.74 (which is higher than the overdrive ratio normally found in known automatic transmissions), thereby providing increased acceleration when the automatic transmission is in fourth forward gear.
The present invention may be used with other layouts of planetary gear train. The automatic transmission of the present invention is primarily intended for use in a motor vehicle.
Claims (5)
1. An automatic transmission comprising a housing; a planetary gear train mounted within the housing; an input drive shaft for providing input drive to the planetary gear train; an output drive shaft connected with an output drive from the planetary gear train; a first clutch connected between the input drive shaft and a first drive input to the planetary gear train; a second clutch connected between a first reaction input to the planetary gear train and the housing; and a third clutch connected between a second drive input to the planetary gear train and the input drive shaft; wherein for first forward gear ratio the first clutch is engaged; for second forward gear ratio the first and second clutches are engaged; and for third forward gear ratio the first, second and third clutches are engaged.
2. An automatic transmission as claimed in
Claim 1, further comprising a fourth clutch connected between the first reaction input and the housing, wherein for fourth forward gear ratio the first, second, third and fourth clutches are engaged.
3. An automatic transmission as claimed in
Claim 1 or Claim 2, wherein the planetary gear train comprises first and second planetary gear sets; the first planetary gear set comprising a sun gear, a ring gear, first and second pinion gears, and a planet carrier on which the first and second pinion gears are rotatably mounted, the first pinion gear engaging the sun gear and the second pinion gear and the second pinion gear engaging the ring gear and the first pinion gear; the second planetary gear set comprising a sun gear, a ring gear, a pinion gear engaging the sun gear and the ring gear, and a planet carrier on which the pinion gear is rotatably mounted; wherein the sun gear of the first planetary gear set is connected with the ring gear of the second planetary gear set and the planet carrier of the first planetary gear set is connected with the sun gear of the second planetary gear set; and wherein the first drive input is connected to the sun gear of the first planetary gear set and the ring gear of the second planetary gear set; the second drive input is connected to the ring gear of the first planetary gear set; the third drive input is connected to the planet carrier of the first planetary gear set and the sun gear of the second planetary gear set; the first reaction input is connected to the planet carrier of the first planetary gear set and the sun gear of the second planetary gear set; and the planet carrier of the second planetary gear set is connected to the output drive shaft.
4. An automatic transmission as claimed in any one of Claims 1 to 3, further comprising a fifth clutch and a one-way coupling associated with the first clutch, the fifth clutch being engageable to overrun the engaged one-way coupling to provide braking to the planetary gear train from an engine driving the input drive shaft.
5. An automatic transmission substantially as herein described with reference to, and as shown in, the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9602272A GB2309755B (en) | 1996-02-05 | 1996-02-05 | Automatic transmission |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9602272A GB2309755B (en) | 1996-02-05 | 1996-02-05 | Automatic transmission |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9602272D0 GB9602272D0 (en) | 1996-04-03 |
| GB2309755A true GB2309755A (en) | 1997-08-06 |
| GB2309755B GB2309755B (en) | 1999-06-16 |
Family
ID=10788124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9602272A Expired - Fee Related GB2309755B (en) | 1996-02-05 | 1996-02-05 | Automatic transmission |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2309755B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4748869A (en) * | 1979-08-14 | 1988-06-07 | Nissan Motor Company, Limited | Automatic transmission for an automotive vehicle |
| US4934215A (en) * | 1986-12-09 | 1990-06-19 | Aisin-Warner Kabushiki Kaisha | Automatic transmission |
-
1996
- 1996-02-05 GB GB9602272A patent/GB2309755B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4748869A (en) * | 1979-08-14 | 1988-06-07 | Nissan Motor Company, Limited | Automatic transmission for an automotive vehicle |
| US4934215A (en) * | 1986-12-09 | 1990-06-19 | Aisin-Warner Kabushiki Kaisha | Automatic transmission |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2309755B (en) | 1999-06-16 |
| GB9602272D0 (en) | 1996-04-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20010205 |