GB2033029A - Variable-ratio gearing - Google Patents

Variable-ratio gearing Download PDF

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Publication number
GB2033029A
GB2033029A GB7835791A GB7835791A GB2033029A GB 2033029 A GB2033029 A GB 2033029A GB 7835791 A GB7835791 A GB 7835791A GB 7835791 A GB7835791 A GB 7835791A GB 2033029 A GB2033029 A GB 2033029A
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GB
United Kingdom
Prior art keywords
coupling
planetary gearset
transmission
intermediate member
transmission mechanism
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
Application number
GB7835791A
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GB2033029B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GKN Automotive Ltd
Original Assignee
GKN Transmissions Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by GKN Transmissions Ltd filed Critical GKN Transmissions Ltd
Priority to GB7835791A priority Critical patent/GB2033029B/en
Publication of GB2033029A publication Critical patent/GB2033029A/en
Application granted granted Critical
Publication of GB2033029B publication Critical patent/GB2033029B/en
Expired legal-status Critical Current

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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
    • F16H47/00—Combinations of mechanical gearing with fluid clutches or fluid gearing
    • F16H47/06—Combinations of mechanical gearing with fluid clutches or fluid gearing the fluid gearing being of the hydrokinetic type
    • F16H47/065—Combinations of mechanical gearing with fluid clutches or fluid gearing the fluid gearing being of the hydrokinetic type the mechanical gearing being of the friction or endless flexible member type
    • 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
    • F16H45/00—Combinations of fluid gearings for conveying rotary motion with couplings or clutches
    • F16H45/02—Combinations of fluid gearings for conveying rotary motion with couplings or clutches with mechanical clutches for bridging a fluid gearing of the hydrokinetic type
    • F16H2045/0221—Combinations of fluid gearings for conveying rotary motion with couplings or clutches with mechanical clutches for bridging a fluid gearing of the hydrokinetic type with damping means
    • F16H2045/0268—Combinations of fluid gearings for conveying rotary motion with couplings or clutches with mechanical clutches for bridging a fluid gearing of the hydrokinetic type with damping means the damper comprising a gearing

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Transmission Devices (AREA)

Abstract

A variable speed ratio transmission mechanism incorporates a fluid coupling 14, 15, an expanding-pulley gear 51, 52 to provide variations in ratio and a planetary gearset 23 to provide reverse drive. The planetary gearset 23 is positioned generally within the space surrounded by the fluid coupling 14, <IMAGE>

Description

SPECIFICATION CvT reverse in fluid coupling The invention relates to variable speed ratio transmissions and particularly to such transmissions in which the drive ratio is continuously variable over a range of ratios.
Such a transmission normally incorporates a friction drive unit of variable geometry such that the effective diameters of driving and/or driven elements are varied to vary the transmission ratio between the driving and driven elements. Such a drive unit will be referred to as a variator. One form of variator incorporates a friction belt or chain drive between two adjustable V-pulleys, the pulleys with their adjusting mechanisms being known as sheaves. The two sides of one pulley are moved closer together while the corresponding halves of the other pulley are moved apart so that the belt or chain engages smaller and larger diameter regions of the two pulleys respectively to vary the drive ratio.
It is already known from U.K. patent specification 1,477,747 to provide a transmission suitable for a vehicle which incorporates a fluid coupling (in that example in the form of a hydrodynamic torque converter) a planetary reversing gear and a variator. The present invention is concerned with a transmission of this type.
In designing a motor vehicle transmission it is particularly important to ensure that the transmission can be fitted into the space provided in an existing vehicle design for a friction clutch and a conventional syncro-mesh gear box. This is because a conventional vehicle with a conventional transmission is normally designed in such a way that there is no spare space around the transmission. It could even be desirable to produce a transmission which could occupy a space smaller than that of the conventional clutch and gear box if the vehicle is being designed with the continuously variable transmission in mind and there is no requirement for a conventional manual transmission.
An object of the present invention is to provide a continuously variable speed ratio transmission mechanism which includes a facility for effective disconnection and gradual take up of drive (as can be provided by a conventional torque converter or other fluid coupling or by a conventional friction clutch) and which can be fitted into a small space.
According to the present invention there is provided a variable speed ratio transmission mechanism comprising: an input member; a generally annular fluid coupling having a driving member connected to the input member and a driven member connected to one element, other than the planet carrier, of a planetary gearset; an intermediate member connected to the other element, other than the planet carrier, of the planetary gearset; a forward clutch arranged to lock an element of the planetary gearset to another element thereof to provide a direct drive from the coupling to the intermediate member; a reverse brake arranged to hold the planet carrier of the planetary gearset against rotation to provide a reverse drive; and a variator (as herein defined) connected between the intermediate member and the output of the transmission; the planetary gearset being disposed at least partially within the space surrounded by the annulus of the fluid coupling. This location of the planetary gearset enables the whole of the transmission mechanism to be compact.
Preferably the input member is connected to the sun gear of the planetary gearset and the intermediate member is connected to the ring gear thereof. With this arrangement the over-all forward ratio for a given variator ratio is higher (normally less reduction) than the corresponding reverse ratio and this is desirable in a vehicle transmission.
Preferably a lock up clutch is connected between the driving member and the driven member of the fluid coupling. This enables the efficiency of the transmission to be improved in that power losses in the fluid cou piing due to slip can be eliminated in most operating conditions of a vehicle.
Preferably the input member is connected to the outer part of the driving member and the coupling extends around the driven member thereof, the intermediate member extending axially through the driving member of the coupling. This arrangement assists in an overall compact design in that it enables the reverse brake, which is typically of smaller diameter than the fluid coupling, to be arranged on the side of the fluid coupling away from the input member to the transmission mechanism.
Preferably the planet carrier is supported on a sleeve which surrounds the intermediate member and extends through the driving member of the coupling to the reverse brake.
An embodiment of the invention will now be described with reference to the accompanying drawing which is a cross sectional view through a transmission assembly according to the invention.
The drawing shows a variable speed ratio transmission mechanism which is intended for use in a front wheel drive motor vehicle. The transmission incorporates an input member 11 which is intended for connection to the output shaft of an internal combustion engine.
The input member is a generally circular pressing to which is bolted a cast annular starter ring gear 1 2 which has external teeth 1 3 for engagement by a starter motor for the vehicle engine. A fluid coupling incorporates a driving member 14 and a driven member 1 5 which are both of conventional toroidal form. The casing 1 6 of the driving member incorporates a cylindrical extension sleeve 17 which is bolted to the input member 11 by the same bolts 18 which secure the starter ring gear 1 2 to the input member 11. The sleeve 1 7 thus in effect forms an extension of the input member.As shown, the extension sleeve extends around the driven member 15 of the coupling and is connected to the outer part of the driving member of the coupling.
The casing 1 6 of the driving member of the coupling extends inwardly and is supported in a ball bearing 1 9 which is in turn carried in a bearing housing 21 supported in the main casing 22 of the transmission. This bearing 1 9 also serves to support the input member 11.
The driven member 1 5 of the coupling is connectable to a planetary gearset 23 in a way which will be described subsequently.
The planetary gearset 23 incorporates a ring gear 24 which is splined to a shaft 25 which forms the intermediate member of the transmission. The sun gear 26 of the gear set is connected directly to the driven member 1 5.
Planet gears 27 are supported on a planet carrier 28 which in turn is integral with a sleeve 29 which runs on the shaft 25 and extends through the coupling. The member which carries ring gear 24 also carries a clutch plate 31 on a series of dog teeth 32.
Clutch plate 31 is arranged to co-operate with a fixed pressure plate 33 carried on an extension 34 of the driven member 1 5 and a movable pressure plate 35 which is carried for rotation with output member 15 but is movable axially by engagement of external dog teeth 36 with corresponding dog teeth 37 on the extension 34. An annular piston 38 acting in a cylinder 39 is arranged on pressurization of the cylinder to force pressure plate 35 towards pressure plate 33 to clamp clutch plate 31 therebetween. This clutch thus in effect locks together the sun gear 26 and ring gear 24. The planetary gearset is thus locked up so that drive is established between the driven member 1 5 of the fluid coupling and the intermediate member 25. This mode of operation is used for forward drive of the transmission.
Sleeve 29 associated with the planet carrier 28 carries the rotary part 40 of a reverse brake. The rotary part 40 is in the form of a clutch plate but the friction device as a whole is referred to as a brake because in operation the plate is brought to rest rather than engaging with another rotating part. The rotary part 40 lies between a fixed pressure plate 41 and an annular piston 42 which forms a further pressure plate. Piston 42 is arranged in cylinder 43 and when the cylinder is pressurized the piston is moved towards the fixed pressure plate 41 to clamp the rotary part 40 of the brake. In this way the carrier is held stationary. In this condition the ring gear 24 rotates in the opposite direction from the sun gear 26 and thus drives the intermediate member 25 in a rotational direction opposite from that of the input member and fluid coupling.In this way reverse drive is established. Whereas during forward drive the intermediate member rotates at the same speed as the driven member of the coupling, in reverse drive the ratio is reduced by the planetary gearset so that reverse gear is lower than forward gear. Clearly the control system for the transmission must be such that the forward clutch 31, 33, 35 is never engaged at the same time as the brake 39, 41, 42 is engaged.
A further feature incorporated in this example of a transmission according to the present invention is a lock up clutch arranged between the driving and driven members of the fluid coupling to lock the coupling and prevent power loss due to slip in the coupling.
This friction clutch incorporates an axially fixed pressure plate 44 which is integral with the starter ring gear 1 2 and an annular piston 45 slidable in a cylinder 46 formed in the input member 11 of the transmission. A clutch plate 47 is connected to the dog teeth 37 of extension member 34 of the driven member 1 5 and is engaged between the pressure plate 41 and piston 45 so that pressurization of cylinder 46 engages the clutch and locks up the driving and driven members of the coupling.
The intermediate member 25 extends beyond the assembly of fluid coupling and brakes and clutches and carries the input sheave 51 of a variator. The output sheave 52 of the variator is carried on an output shaft 53 of the transmission. The structure of the two sheaves is identical and thus the input sheave only will be described in detail.
Input sheave 51 incorporates a fixed pulley side 48 secured to the intermediate member 25 and a movable pulley side 49 which is splined at 54 to the intermediate member so as to be movable axially with respect to the intermediate member but rotational with that member. The outer end of the movable pulley side 49 incorporates an axial extension 55 which provides a hydraulic cylinder 56. A piston 57 associated with this cylinder is splined at 58 to the intermediate member but is axially fixed by means of a circlip 59.
Pressurization of the cylinder 56 tends to move the pulley side 49 towards or away from the pulley side 48 so that a V-belt or Vchain arranged in the V formed by the two pulley halves and shown in chain dotted outline at 61 engages with the pulley at an effective diameter dependent on the spacing of the two pulley parts. When the effective diameters of the two pulleys which form parts of the input and output sheaves are varied in opposite senses by appropriate pressurization of their associated cylinders the effective di ameters of the two pulleys vary in opposite senses with respect to each other and thereby produce a variation in the transmission ratio.
Thus the two sheaves and their associated drive belt or chain form a variator.
In order to take the substantial transverse loads of the drive belt or chain on the intermediate member 25 it is suported in two substantial ball bearings 62 and 63. Bearing 62 supports the intermediate member directly whereas bearing 63 supports the intermediate member through the intermediary of the axially fixed piston 57.
The output shaft 53 on which output sheave 52 is mounted carries an output gear or sprocket 64 from which drive can be transmitted to the differential or other part of the vehicle transmission.
The transmission also incorporates a pump shown diagrammatically at 65 as a gear pump and this pump provides hydraulic pressure for operation of the transmission mechanism. The pump supplies fluid under pressure to a control mechanism (not shown) which in turn distributes fluid as required to a series of fluid passages which will now be described. To provide these passages, the intermediate member 25 is hollow to provide a central passage 66 and an annular passage 67 separated by a sleeve 68. In order to operate the forward clutch, fluid under pressure is supplied through inlet 70 from where it passes along annular passage 67 to internal drilling 69 in the hub of the driven member 1 5 of the fluid coupling. From there it is supplied to the cylinder 39 to operate the forward clutch.
Fluid passed along this same route is connected to the interior of the fluid coupling to insure that the coupling is full of fluid by means of a further branch connection 71.
In order to operate the reverse brake, fluid is supplied to inlet 72 and through annular channel 73 and drilling 74 to the interior of cylinder 43.
In order to operate the lock up clutch, fluid is supplied through inlet 75, the central passage 66 and a radial passage 76 formed in the inlet member to cylinder 46.
Pressurization of sheave 56 takes place via inlet 77, drilling 78 in the intermediate member and a passage 79 in the movable pulley side 49. There is a corresponding pressure supply for the output sheave 52.
In over-all operation of the transmission, the control system is operated in such a way that appropriate clutches and brakes are engaged and disengaged as required and such that appropriate pressures are applied to the two sheaves to select an appropriate ratio.
Although the invention has been described with a simple two element fluid coupling, it would be possible to replace this fluid coupling by a more complex fluid coupling such as a three element torque converter. Also, the variator has been described as being of the variable V-belt or chain pulley type but other types of variator could be used.
The transmission illustrated is simple and compact and with an appropriate control system can provide automatic ratio selection to suit the operating conditions of the vehicle.
A major contributory factor in the compactness of the transmission is the fact that the planetary gearset 23 is disposed generally within the space surrounded by the annulus of the fluid coupling. A small planetary gearset which can fit in this space is facilitated by the fact that the gear set is loaded only during reverse operation because in forward drive the carrier is freely rotatable and the sun gear is clutched to the ring gear.

Claims (6)

1. A variable speed ratio transmission mechanism comprising: an input member; a generally annular fluid coupling having a driving member connected to the input member and a driven member connected to one element, other than the planet carrier, of a planetary gearset; an intermediate member connected to the other element, other than the planet carrier, of the planetary gearset; a forward clutch arranged to lock an element of the planetary gearset to another element thereof to provide a direct drive from the coupling to the intermediate member; a reverse brake arranged to hold the planet carrier of the planetary gearset against rotation to provide a reverse drive; and a variator (as herein defined) connected between the intermediate member and the output of the transmission; the planetary gearset being disposed at least partially within the space surrounded by the annulus of the fluid coupling.
2. A transmission mechanism as claimed in Claim 1 in which the input member is connected to the sun gear of the planetary gearset and the intermediate member is connected to the ring gear thereof.
3. A transmission mechanism as claimed in Claim 1 or Claim 2 including a lock-up clutch connected between the driving member and the driven member of the fluid coupling.
4. A variable ratio transmission as claimed in any preceding claim in which the input member is connected to the outer part of the driving member of the coupling and extends around the driven member thereof, the intermediate member extending axially through the driving member of the coupling.
5. A transmission mechanism as claimed in any preceeding claim in which the planet carrier is supported on a sleeve which surrounds the intermediate member and extends through the driving member of the coupling to the reverse brake.
6. A variable ratio transmission mechanism substantially as described with reference to and as illustrated by the accompanying drawings.
GB7835791A 1978-09-06 1978-09-06 Variable-ratio gearing Expired GB2033029B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7835791A GB2033029B (en) 1978-09-06 1978-09-06 Variable-ratio gearing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7835791A GB2033029B (en) 1978-09-06 1978-09-06 Variable-ratio gearing

Publications (2)

Publication Number Publication Date
GB2033029A true GB2033029A (en) 1980-05-14
GB2033029B GB2033029B (en) 1982-11-03

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GB7835791A Expired GB2033029B (en) 1978-09-06 1978-09-06 Variable-ratio gearing

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3203252A1 (en) * 1981-02-04 1982-08-26 Aisin-Warner K.K., Anjo, Aichi AUTOMATIC CONTINUOUSLY GEARBOX
DE3202591A1 (en) * 1981-02-07 1982-08-26 Aisin-Warner K.K., Anjo, Aichi PRESSURE DISTRIBUTOR SYSTEM FOR AN AUTOMATIC STEPLESS GEARBOX
EP0073546A1 (en) * 1981-08-28 1983-03-09 Van Doorne's Transmissie B.V. Transmission, in particular for a motor vehicle
JPH01283461A (en) * 1989-03-24 1989-11-15 Aisin Aw Co Ltd Belt type continuously variable automatic transmission for vehicle
EP0864778A2 (en) 1997-03-14 1998-09-16 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing
EP0896894A3 (en) * 1997-08-12 1999-02-24 Fuji Jukogyo Kabushiki Kaisha Automatic transmission
EP0911545A1 (en) 1997-10-23 1999-04-28 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing
EP0918175A3 (en) * 1997-10-23 1999-10-20 Fuji Jukogyo Kabushiki Kaisha Combined CVT-clutch housing cooled by lubricating oil
EP0897074A3 (en) * 1997-08-12 1999-10-20 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing and lock-up clutch

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3203252A1 (en) * 1981-02-04 1982-08-26 Aisin-Warner K.K., Anjo, Aichi AUTOMATIC CONTINUOUSLY GEARBOX
DE3202591A1 (en) * 1981-02-07 1982-08-26 Aisin-Warner K.K., Anjo, Aichi PRESSURE DISTRIBUTOR SYSTEM FOR AN AUTOMATIC STEPLESS GEARBOX
EP0073546A1 (en) * 1981-08-28 1983-03-09 Van Doorne's Transmissie B.V. Transmission, in particular for a motor vehicle
US4601368A (en) * 1981-08-28 1986-07-22 Van Doorne's Transmissie B.V. Infinitely variable ratio transmission
JPH01283461A (en) * 1989-03-24 1989-11-15 Aisin Aw Co Ltd Belt type continuously variable automatic transmission for vehicle
JPH0448978B2 (en) * 1989-03-24 1992-08-10 Aisin Aw Co
EP0864778A2 (en) 1997-03-14 1998-09-16 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing
EP0864778A3 (en) * 1997-03-14 1999-01-07 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing
US6099428A (en) * 1997-03-14 2000-08-08 Fuji Jukogyo Kabushiki Kaisha Continuously variable transmission
EP0896894A3 (en) * 1997-08-12 1999-02-24 Fuji Jukogyo Kabushiki Kaisha Automatic transmission
EP0897074A3 (en) * 1997-08-12 1999-10-20 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing and lock-up clutch
US6066059A (en) * 1997-08-12 2000-05-23 Fuji Jukogyo Kabushiki Kaisha Continuously variable transmission system
EP0911545A1 (en) 1997-10-23 1999-04-28 Fuji Jukogyo Kabushiki Kaisha Torque converter comprising reversing gearing
EP0918175A3 (en) * 1997-10-23 1999-10-20 Fuji Jukogyo Kabushiki Kaisha Combined CVT-clutch housing cooled by lubricating oil
US6066058A (en) * 1997-10-23 2000-05-23 Fuji Jukogyo Kabushiki Kaisha Automatic transmission

Also Published As

Publication number Publication date
GB2033029B (en) 1982-11-03

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee