GB2164106A - Continuously variable transmissions - Google Patents
Continuously variable transmissions Download PDFInfo
- Publication number
- GB2164106A GB2164106A GB08422378A GB8422378A GB2164106A GB 2164106 A GB2164106 A GB 2164106A GB 08422378 A GB08422378 A GB 08422378A GB 8422378 A GB8422378 A GB 8422378A GB 2164106 A GB2164106 A GB 2164106A
- Authority
- GB
- United Kingdom
- Prior art keywords
- speed change
- gear
- gearing
- change portion
- members
- 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
Links
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
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H37/0846—CVT using endless flexible members
-
- 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
- F16H37/00—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00
- F16H37/02—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings
- F16H37/06—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts
- F16H37/08—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing
- F16H37/0833—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths
- F16H37/084—Combinations of mechanical gearings, not provided for in groups F16H1/00 - F16H35/00 comprising essentially only toothed or friction gearings with a plurality of driving or driven shafts; with arrangements for dividing torque between two or more intermediate shafts with differential gearing with arrangements for dividing torque between two or more intermediate shafts, i.e. with two or more internal power paths at least one power path being a continuously variable transmission, i.e. CVT
- F16H2037/0866—Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Transmission Devices (AREA)
Abstract
A transmission 10 suitable for an automobile provides a wide range of reduction gear ratio. Planetary gearing 20a and a variable speed change portion 30 connect an engine 50 to a differential 63 and thus to ground wheels. The gearing 20a includes a ring gear 21 connected to an input shaft 51 from the engine, a pinion 22, a carrier 23 and a sun 24 connected to respective speed change members or pulleys 33 and 34 of the variable speed change portion 30, one of which is driven by the other through a belt 35. A power transmission may be connected between one of the speed change members and one of the pulleys. The variable speed change portion may comprise spherical or frictional means rather than a belt and pulleys. <IMAGE>
Description
SPECIFICATION
Continuously variable transmissions
The invention relates to continuously variable transmissions (hereinafter described as CVTs) which can change their reduction ratios over a wide range and which can be made compact and of light weight.
The invenion provides a continuously variable transmission comprising a gear train having at least three members, and a variable speed change portion comprising one speed change member for driving another, one of the said three members being connected to each of the speed change members.
The aforementioned gearing may be planetary and comprise a first sun member, second ring member, a pinion gear that meshes with these two members, and a third carrier member for the pinion gear. A single or a pair of pinion gears may be used or the sun and ring gear may be replaced by two sun gears having a different shape or arranged in a different way. The third or carrier member may carry an idle gear instead of a pinion gear. Various modifications can be made to the gearing, as long as it splits the torque on the input shaft.
One of the three members of the gearing is generally connected to the input shaft of the CVT.
In case of planetary gearing, one of the sun gear, the ring gear, and the carrier is connected to the input shaft of the CVT, and the two others are connected to one of the speed change members of the variable speed change portion. One of the two other members of gear train is coupled to one speed change member (input shaft), and the other to the other speed change member (output shaft). A belt, spherical transmitting means, or frictional transmitting means can be used for the variable speed change portion.
Torques T1, T2 and T3 distributed to the first, second and third members respectively may be so set that T3 < T1 < T2 holds provided that the member of the gearing which is connected to the input shaft is the first member and the others are the second and third members. Where the power transmission portion has a reduction ratio of i2, the torques T2 and T3 applied to the second and third members are such that:
T'=T2i2 or T3'=T3i2.
The result is that T3 (or T3') < T2 (or T2').
The connection between the gearing and the variable speed change portion may be direct.
Where the input and output shafts of the speed change portion are in parallel, the shafts can be coupled so as to be rotatable in the same sense by a power transmission which comprises gears, belts or chains, for example. It is also possible to maintain the reduction ratio i2 of the power transmission portion constant. Even if a small speed change portion is used whose range of reduction is limited, the combination of the gearing and the speed change portion can make the range of the reduction ratio of the whole CVT considerably greater than that obtained when only the variable speed change portion is used. Further, the torque between the speed change member and the power transmission member, such as a belt, of the speed change portion is reduced, and contributes the durability of the CVT.
DRA WINGS:
Figures 1 and 2 are a plan view and a side elevation respectively of a front portion of an automobile equipped with a CVT according to the invention;
Figure 3 is a block diagram of a CVT according to the invention;
Figures 4a and 4b, 5a and 5b, 6a and 6b, 7 and 8 are block diagrams of other CVTs according to the invention; and
Figures 9 to 17 are schematic representations of CVTs according to the invention.
Referring first to Figs. 1 and 2, a CVT 10 is particularly suitable for the transmission of a front-wheel drive automobile having an engine 50. One of the three members (1) of a gearing 20 in Fig. 3 is connected to an input shaft, while the two others 2, 3 are connected to respective ones of a pair of speed change members in a variable (nonstep) speed change portion. The lower of the speed change members is coupled to an output shaft.
Referring next to Fig. 4a, the gearing is a planetary gearing 20a which includes a ring gear 21, a pinion gear 22, a carrier 23 which carries the gear 22, and a sun gear 24. The ring gear 21 is linked to the input shaft, and the sun gear 24 is connected either to the output shaft or to the other speed change member. Although the planetary gearing 20a is connected to the input shaft through the ring gear in Fig. 4a, it is also possible to connect either the carrier 23 or the sun gear 24 to the input shaft.
Referring to Fig. 5a, there is shown a twin-pinion planetary gearing 20b which includes twin pinion gears 22a, 22b, and a carrier 23a. The carrier 23a is connected to the input shaft, and the sun gear 24 is joined to the output shaft and to the other member of the nonstep portion from the ring gear 21.
Referring to Fig. 6a, a gearing 20c is equipped with a first sun gear 24a, a second sun gear 24b, a pinion gear 22c that meshes with both sun gears, and a carrier 23b which carries the pinion gear 22c. A further example of the construction of the gearing 20c is shown in Fig. 6b.
Referring to Fig. 7, there is shown one of the members (2) of the gearing 20 not connected with the input shaft but connected via a power transmission portion to one of the speed change members of the variable speed change portion. If T1, T2, T3' and T2' are the torques imposed respectively on the input shaft, the member 1, the member 2, and the driven section of the power transmission portion coupled to one of the speed change members of the speed change portion, the rotational velocity of the input shaft is so lowered and transmitted that the relation T3 < T2', preferably T3T1 T2', more preferably T3 < T1 < T2' holds.
The arrangement shown in Fig. 8 differs from that shown in Fig. 7 in that the member 3 of the gearing 20 and the other speed change member of the variable speed change portion are connected together through the power transmission portion and also connected to the output shaft. In this case, the relationship T3' < T2 holds between the rotating speeds of the shafts, where T3' is the rotating speed of the driven section of the power transmission portion.
Preferably the relation T3' < T1 < T2', and more preferably the relation T3T1 T2 hold similarly.
The CVT 10 shown in Fig. 9 is placed between the internal combustion engine 50 and a clutch mechanism 60 of an automobile. The CVT 10 comprises the usual planetary gearing 20 and variable speed change portion 30. The gearing 20 as before comprises a ring gear 21 connected to an output shaft 51 of the engine 50, a carrier 23 for a pinion gear 22 connected to an input shaft 31 of the speed change portion 30, and a sun gear 24.This sun gear 24 is linked to the output shaft 32 of the speed change portion 30 via gearing 40 (a gear 41) which constitutes a power transmission portion having a reduction gear ratio i2. p is the radius ratio of the planetary gearing 20, i.e. the ratio of the number of the teeth of the sun gear Zs to the number of the teeth of the ring gear ZR The speed change portion 30 comprises a pulley 33 mounted on the input shaft 31, another pulley 34 mounted on the output shaft 32, and a belt 35 trained around the pulleys. The effective diameter of one or both of the pulleys is adjusted by an operating device (not shown) to vary the reduction gear ratio i1. If Ti is the torque transmitted from the output shaft 51 and applied to the ring gear 21, the carrier 23 is subject to a torque (1 +p) Ti, which is applied to the speed change portion 30.Accordingly, the torque component (1 +p) Ti.il is transmitted to the pulley 34 on the output side. Meanwhile, the sun gear 24 produces a torque pTi, which is changed to a torque component pTi.i2 and transmitted to the output side by the gearing 40. Therefore, the output shaft 32 delivers a torque TO=(1 +p)Ti.il-pTi.i2' and the total reduction ratio of the whole CVT is T0/Ti=(1 +,p)il-p.i2.
If the radius ratio p of the sun gear of the planetary gear to the ring gear is 0.35, the belt reduction ratio il of the speed change portion 30 changes from 1/2 to 2, and the reduction ratio i2 of the gearing 40=1.0. When the input torque is Ti, the output torque delivered by the output shaft can vary from TO=(1+0.35) TiX2-0.35 T1X1=2.35 Ti to (1+0.35) TiX 1/2-0.35 TiX1=0.325 Ti. The reduction ratio and its range obtained in this way are compared with those obtained by a conventional belt type CVT alone in the following Table:
reduction ratio range of ratio the invention 2.35 to 0.325 7.23
Prior art (belt type) 2 to 1/2 2i1/2=4 The CVT of the invention uses the planetary gearing to enlarge the range of the reduction ratio.When it is desired to make the range of the reduction ratio of the whole CVT substantially as large as the conventional system, the dimensions of the variable speed change portion can be made small and the whole CVT miniaturized.
The output shaft 32 whose speed is controlled is connected via the clutch 60 to an output shaft 61 coaxial therewith. The clutch 60 is shown on the right side in Fig. 9, and comprises a planetary gear train including brake and clutch means. The output shaft 32 is connected to ground wheels (not shown) on both sides via a gear train 62 and a differential gear 63. The
CVT 10 is coupled to the engine 50 at all times, and the speed change portion 30 can operate even when the clutch 60 is let out. By causing the CVT 10 to cooperate with a control system, the automobile can readily be set in motion with a low reduction gear ratio, and so achieve a high acceleration.
Fig. 10 differs from Fig. 9 in that the power transmission connecting the sun gear of the planetary gearing to the output shaft is a chain 42. In Fig. 11, the power transmission is a Vbelt 43. Fig. 12 differs in the arrangement of the mechanisms. In particular, the pulley 33 on the input side of the variable speed change portion is mounted coaxially on the output shaft 51 of the engine and the output shaft 25 of the sun gear of the planetary gearing 20 extends to the right. The clutch 60 is mounted coaxially on the output shaft 32 of the variable speed change portion
Fig. 13 is similar to Fig. 9 except that the input and output of the planetary gearing 20 are reversed. Fig. 14 also is similar but the input and output shafts of the variable speed change portion 30 are reversed.The input shaft 31 of the variable speed change portion 30 is located at lower position, and is connected to the carrier 23 by the gear 40. The output shaft 32 of the speed change portion 30, which is the output shaft of the whole CVT 10 is aligned with the centre axis of the sun gear 24. Thus the gear advantageously provides a coaxial arrangement of the input and output shafts. It is to be noted that the output shaft 32 can be connected to the input shaft 31 of the speed change portion.
Fig. 15 shows a further CVT in which the planetary gearing has twin pinions. The input shaft 51 is connected to the carrier 23 which carries a first pinion 22a and a second pinion 22b. The ring gear 23 is linked to the input shaft 31 of the variable speed change portion 30. The sun gear 24 is connected to the output shaft 32 of the speed change portion 30 via the gearing 40.
Fig. 16 is similar to Fig. 3 except for the gearing 20 which consists of a first sun gear 24a connected to the input shaft, a second sun gear 24b connected via gearing 40 to the output shaft 32 of the variable speed change portion 30, a pinion gear 22c meshing with both sun gears 24a, 24b and a carrier 23b carrying the pinion gear 22c. The carrier 23b is connected to the input shaft 31 of the speed change portion 30.
Fig. 17 is similar to Fig. 16 in that a single pinion 22 meshes with the first sun gear 24a and the second sun gear 24b but a pair of pinion gears 22c meshes with the sun gears 24a and 24b.
Claims (6)
1. A continuously variable transmission comprising a gear train having at least three members, and a variable speed change portion comprising one speed change member for driving another, one of the said three members being connected to each of the speed change members.
2. A transmission according to claim 1. wherein the gearing is planetary.
3. A transmission according to claim 2 wherein the gearing consists of a first sun gear, a second sun gear, a pinion gear meshing with these two sun gears, and a carrier for the pinion gear.
4. A transmission according to claim 2 or claim 3 wherein there is provided a pair of pinion gears.
5. A transmission according to any preceding claim wherein at least one of the two members is connected to the speed change member via a power transmission.
6. A continuously variable transmission as herein described with reference to any of Figs. 3, 4a and 4b, 5a and 5b, 6a or 6b, or any of 7 to 17.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8422378A GB2164106B (en) | 1984-09-05 | 1984-09-05 | Continuously variable transmissions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8422378A GB2164106B (en) | 1984-09-05 | 1984-09-05 | Continuously variable transmissions |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8422378D0 GB8422378D0 (en) | 1984-10-10 |
| GB2164106A true GB2164106A (en) | 1986-03-12 |
| GB2164106B GB2164106B (en) | 1989-06-14 |
Family
ID=10566273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8422378A Expired GB2164106B (en) | 1984-09-05 | 1984-09-05 | Continuously variable transmissions |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2164106B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2220236A (en) * | 1988-06-17 | 1990-01-04 | Malcolm Tomlinson | Variable ratio transmission using variator and geared drive in parallel |
| FR2917467A3 (en) * | 2007-06-18 | 2008-12-19 | Renault Sas | Starter for e.g. direct injection and low compression ratio oil engine of motor vehicle, has gear reduction system with output connected to toothed pinion cooperating with toothed crown, where reduction system presents variable drive ratio |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB788963A (en) * | 1954-11-25 | 1958-01-08 | Marcel Desire Alfred Bert | Improvements in variable speed gears |
| GB879157A (en) * | 1957-02-25 | 1961-10-04 | Renault | Improvements in or relating to differential transmissions for motor vehicles |
| GB958652A (en) * | 1959-10-09 | 1964-05-21 | Massey Ferguson Services Nv | Improvements in variable speed reduction gearing |
| GB1106790A (en) * | 1964-05-02 | 1968-03-20 | Zahnradfabrik Friedrichshafen | Improvements in or relating to transmission arrangements |
| GB1364962A (en) * | 1971-06-21 | 1974-08-29 | Orshansky Transmission Corp | Power transmission |
| GB1494128A (en) * | 1974-04-06 | 1977-12-07 | Papadimitriou Ioannis | Transmission system |
| GB1515687A (en) * | 1975-11-15 | 1978-06-28 | Gkn Transmissions Ltd | Transmission assemblies |
| GB1575381A (en) * | 1978-03-02 | 1980-09-24 | British Leyland Cars Ltd | Variable-speed transmissions |
| GB1603633A (en) * | 1978-05-30 | 1981-11-25 | Reimers Piv Antrieb Kg W | Continuously variable transmissions |
| GB1603853A (en) * | 1978-05-08 | 1981-12-02 | British Leyland Cars Ltd | Variableratio transmissions |
| GB2115091A (en) * | 1982-02-22 | 1983-09-01 | Valeo | Transmission between a power input and an output shaft suitable for a motor vehicle |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3091132A (en) * | 1958-08-11 | 1963-05-28 | Davis Mfg Inc | Variable ratio drive mechanism |
| GB1119988A (en) * | 1965-10-14 | 1968-07-17 | Nat Res Dev | Transmission system for interconnecting two rotary machines |
| GB1199145A (en) * | 1966-09-02 | 1970-07-15 | English Electric Co Ltd | Rotary Transmission System |
-
1984
- 1984-09-05 GB GB8422378A patent/GB2164106B/en not_active Expired
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB788963A (en) * | 1954-11-25 | 1958-01-08 | Marcel Desire Alfred Bert | Improvements in variable speed gears |
| GB879157A (en) * | 1957-02-25 | 1961-10-04 | Renault | Improvements in or relating to differential transmissions for motor vehicles |
| GB958652A (en) * | 1959-10-09 | 1964-05-21 | Massey Ferguson Services Nv | Improvements in variable speed reduction gearing |
| GB1106790A (en) * | 1964-05-02 | 1968-03-20 | Zahnradfabrik Friedrichshafen | Improvements in or relating to transmission arrangements |
| GB1364962A (en) * | 1971-06-21 | 1974-08-29 | Orshansky Transmission Corp | Power transmission |
| GB1494128A (en) * | 1974-04-06 | 1977-12-07 | Papadimitriou Ioannis | Transmission system |
| GB1515687A (en) * | 1975-11-15 | 1978-06-28 | Gkn Transmissions Ltd | Transmission assemblies |
| GB1575381A (en) * | 1978-03-02 | 1980-09-24 | British Leyland Cars Ltd | Variable-speed transmissions |
| GB1603853A (en) * | 1978-05-08 | 1981-12-02 | British Leyland Cars Ltd | Variableratio transmissions |
| GB1603633A (en) * | 1978-05-30 | 1981-11-25 | Reimers Piv Antrieb Kg W | Continuously variable transmissions |
| GB2115091A (en) * | 1982-02-22 | 1983-09-01 | Valeo | Transmission between a power input and an output shaft suitable for a motor vehicle |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2220236A (en) * | 1988-06-17 | 1990-01-04 | Malcolm Tomlinson | Variable ratio transmission using variator and geared drive in parallel |
| GB2220236B (en) * | 1988-06-17 | 1993-01-13 | Malcolm Tomlinson | Variable ratio power transmission |
| FR2917467A3 (en) * | 2007-06-18 | 2008-12-19 | Renault Sas | Starter for e.g. direct injection and low compression ratio oil engine of motor vehicle, has gear reduction system with output connected to toothed pinion cooperating with toothed crown, where reduction system presents variable drive ratio |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8422378D0 (en) | 1984-10-10 |
| GB2164106B (en) | 1989-06-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19920905 |