GB2329433A - Electrohydraulic control system for a continuously-variable transmission of a vehicle - Google Patents
Electrohydraulic control system for a continuously-variable transmission of a vehicle Download PDFInfo
- Publication number
- GB2329433A GB2329433A GB9719849A GB9719849A GB2329433A GB 2329433 A GB2329433 A GB 2329433A GB 9719849 A GB9719849 A GB 9719849A GB 9719849 A GB9719849 A GB 9719849A GB 2329433 A GB2329433 A GB 2329433A
- Authority
- GB
- United Kingdom
- Prior art keywords
- control
- control system
- transmission
- vehicle
- pin
- 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.)
- Withdrawn
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
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
- F16H61/664—Friction gearings
- F16H61/6648—Friction gearings controlling of shifting being influenced by a signal derived from the engine and the main coupling
-
- 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
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/66—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings
- F16H61/662—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members
- F16H61/66254—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling of shifting being influenced by a signal derived from the engine and the main coupling
- F16H61/66259—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing specially adapted for continuously variable gearings with endless flexible members controlling of shifting being influenced by a signal derived from the engine and the main coupling using electrical or electronical sensing or control means
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Transmission Device (AREA)
Abstract
A CVT control system for a vehicle 100 alters the ratio of the CVT 160 by the movement of a control pin 180 into and out of a hydraulic valve block 200. The movement of the pin 180 is effected by a stepper motor 340 under the control of a CVT controller 320. The CVT controller 320 receives a signal of accelerator pedal displacement and uses the stepper motor 340 to move the pin 180 into and out of the block 200 in accordance with a characteristic curve selected using an input switch 360 to provide a plurality of output characteristics such as: sport S, drive D and economy E.
Description
A Transmission Control Svstem for a Vehicle This invention relates to transmission control systems and in particular to a transmission control system for a continuously variable transmission of a vehicle.
It is known to provide a vehicle with a transmission having an output ratio which can be varied in a continuous manner. It is common for such continuously variable transmissions to be controlled by a mechanical connection between the accelerator pedal and an output ratio varying mechanism forming part of the transmission.
It is an object of this invention to provide an improved transmission control system for a vehicle having a continuously variable transmission.
According to the invention there is provided a transmission control system for a vehicle comprising a means for varying the transmission ratio of a continuously variable transmission of the vehicle, a driver operated acceleration demand means for producing an acceleration demand signal, and a control means operative to control said varying means in response to said acceleration demand signal, wherein the varying means comprises a electrical actuator arranged to control the operation of an output ratio control member of said continuously variable transmission.
The control member may control the operation of a hydraulic valve block of the continuously variable transmission in order to vary the output ratio. The control member may comprise a control pin of the hydraulic valve block and the electrical actuator may comprise a linear electrical actuator arranged to displace said control pin across a range of linear movement. The electrical actuator may comprise a stepper motor.
The control means may be arranged to translate the acceleration demand signal into operation of said control member in a manner defined bv a number of selectable control characteristics.
The invention also provides a vehicle having a transmission control system according to the invention.
The invention will now be described by way of example with reference to the accompanying drawings, in which:
Figure 1 is schematic diagram of a vehicle having a prior art transmission control system;
Figure 2 is a detailed view of part of the prior art system of Figure 1;
Figure 3 is a functional block diagram of the prior art transmission control system of Figure 1;
Figure 4 is a schematic diagram of a vehicle having a transmission control system according to the invention:
Figure is a functional block diagram of the transmission control system of Figure 4; and
Figure 6 is a graphical representation of a set of control characteristics used by the system of Figures 4 and 5 to control the output ratio of the transmission.
Referring to Figures 1 to 3, a vehicle 10 has an engine 12 driving a set of wheels 14 through a continuously variable transmission (CVT) 16.
The output ratio of the C 16 is altered by the movement of a control pin 18 into and out of a hydraulic valve control block 20 forming part of the C 16.
A driver operated accelerator pedal assembly 22 has an accelerator cable 24 connecting it to a throttle butterfly 26 of the engine 12 and movement of the accelerator pedal (not shown separately) is converted into movement of the throttle butterfly 26 in a conventional manner.
A transmission control cable 28 is connected to, and displaced by, movement of the throttle butterfly 26. The control cable 28 is connected to a pulley wheel 30 and when the cable 28 is displaced by the throttle butterfly 26, the cable 28 translate that displacement into rotation of the pulley wheel 30 in parallel to the movement of the butterfly 26. The pin 18 is biased towards a cam 32 which co-rotates with the pulley wheel 30. In this manner, an acceleration demand from the accelerator pedal is translated into movement of the throttle butterfly and a corresponding variation in the output ratio of the CVT 16 in parallel.
Such a prior art system is limited to a single output characteristic of the C 16, because the mechanical connection between the accelerator pedal assembly 22 and the cam 32 means that there is only one range of movement possible for the control pin 16.
The output characteristic is defined by the profile of the cam 32 and is used to vary the output ratio of the CVT 16 through the movement of the control pin 18 into and out of the valve block 20.
An improved transmission control system is now shown with reference to Figures 4 to 6. A vehicle 100 has an engine 120 driving a set of wheels 140 through a continuously variable transmission (CVT) 160.
The output ratio of the CtTT 160 is controlled by the movement of a control pin 180 into and out of a hydraulic valve block 200 forming part of the CVT 160.
A driver operated accelerator pedal assembly 220 has an accelerator cable 240 connected to a throttle butterfly 260 of the engine 120 and movement of an accelerator pedal 280 is translated into movement of the throttle butterfly 260 in a conventional manner.
The accelerator pedal assembly 220 further comprises a potentiometer 300 arranged to detect the displacement of the accelerator pedal 280 and provide an acceleration demand signal indicative of the accelerator pedal angle to a CN controller 320.
The CVT controller 320 electrically controls a stepper motor 340 which moves the pin 180 into and out of the valve block 200 to vary the output ratio of the CvT 160. The stepper motor 340 is controlled according to one of three control characteristics: sport S, drive D and economy E, which are shown with particular reference to Figure 6.
The control characteristics S, D, E are selected using an input to the
CVT controller 320 from a three-way switch 360. The CVT controller 320 also has an input of road speed from a road speed sensor 380 and of engine speed from an engine speed sensor 390.
The CVT controller 320 outputs a signal on a display unit 400 indicative of which characteristic S, D, E is currently selected.
The mechanical isolation of the control pin 180 from the accelerator pedal 280 and the variation of the CVT output ratio by the CN controller 320 operating the stepper motor 340, provides increased flexibility of CN operation. The degree of movement of the pin 180 is defined by the characteristic selected, as described below.
In sport S, the pin 180 is displaced over a large proportion of its full range of movement over the initial range of movement of the accelerator pedal 280. The sports characteristic S provides a sharp increase in road speed for low initial angles of pedal movement.
In drive D, the pin 180 is displaced in a linear fashion over the full range of movement of the accelerator pedal 280 and provides a substantially linear increase in road speed.
In economy E, the pin is displaced by only a small proportion of its full range of movement over the initial range of movement of the accelerator pedal 280. In order to reach high road speeds in economy mode E, the accelerator pedal 280 must be depressed by a much greater angle than in the other modes.
The three characteristic curves S, D, E converge towards their upper and lower limits to ensure that substantially the full range of road speed is available over the full range of movement of the accelerator pedal 280 in each mode.
The provision of a road speed signal and an engine speed signal to the C controller 320 enables it to operate the control of the output ratio under closed loop control, as these inputs allow the calculation of the instant output ratio.
Claims (7)
1. A transmission control system for a vehicle comprising a means for
varying the transmission ratio of a continuously variable transmission
of the vehicle, a driver operated acceleration demand means for
producing an acceleration demand signal, and a control means
operative to control said varying means in response to said acceleration
demand signal, wherein the varying means comprises a electrical
actuator arranged to control the operation of an output ratio control
member of said continuously variable transmission.
2. A transmission control system according to Claim 1, wherein the
control member controls the operation of a hydraulic valve block of the
continuously variable transmission in order to vary the output ratio.
3. A transmission control system according to Claim 1 or Claim 2, the
control member comprising a control pin of the hydraulic valve block
and the electrical actuator comprising a linear electrical actuator
arranged to displace said control pin across a range of linear movement.
4. A transmission control system according to any preceding claim, the
electrical actuator comprising a stepper motor.
o. A transmission control system according to any preceding claim,
wherein the control means is arranged to translate the acceleration
demand signal into operation of said control member in a manner
defined by a number of selectable control characteristics.
6. A transmission control system substantially as described herein
with reference to Figures 4 to 6 of the accompanving drawings.
7. A vehicle having a transmission control system according to any
preceding claim.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9719849A GB2329433A (en) | 1997-09-18 | 1997-09-18 | Electrohydraulic control system for a continuously-variable transmission of a vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9719849A GB2329433A (en) | 1997-09-18 | 1997-09-18 | Electrohydraulic control system for a continuously-variable transmission of a vehicle |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9719849D0 GB9719849D0 (en) | 1997-11-19 |
| GB2329433A true GB2329433A (en) | 1999-03-24 |
Family
ID=10819261
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9719849A Withdrawn GB2329433A (en) | 1997-09-18 | 1997-09-18 | Electrohydraulic control system for a continuously-variable transmission of a vehicle |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2329433A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2349674A (en) * | 1999-05-01 | 2000-11-08 | Rover Group | An automatic transmission with ratio change controlled by an accelerator pedal |
| WO2005065983A1 (en) * | 2003-12-23 | 2005-07-21 | Daimlerchrysler Ag | Device equipped with a unit for actuating a continuously variable motor vehicle transmission |
| BE1021991B1 (en) * | 2014-07-28 | 2016-02-02 | Patrick Haesen | CONTINUOUS VARIABLE TRANSMISSION (CVT) AND DRIVE OF A VEHICLE FITTED WITH SUCH CVT |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4507986A (en) * | 1981-02-24 | 1985-04-02 | Nissan Motor Company, Limited | Control system for motor vehicle |
| US4846019A (en) * | 1986-09-08 | 1989-07-11 | Nissan Motor Co., Ltd. | Ratio control for continuously variable transmission |
| US4976170A (en) * | 1987-08-11 | 1990-12-11 | Honda Giken Kabushiki Kaisha | Method for controlling stepless automatic transmission and apparatus therefor |
| EP0451887B1 (en) * | 1990-04-12 | 1995-06-07 | Van Doorne's Transmissie B.V. | Electronically controlled continuously variable transmission |
| GB2298907A (en) * | 1995-03-14 | 1996-09-18 | Fuji Heavy Ind Ltd | An electrohydraulic control system for a continuously-variable transmission. |
-
1997
- 1997-09-18 GB GB9719849A patent/GB2329433A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4507986A (en) * | 1981-02-24 | 1985-04-02 | Nissan Motor Company, Limited | Control system for motor vehicle |
| US4846019A (en) * | 1986-09-08 | 1989-07-11 | Nissan Motor Co., Ltd. | Ratio control for continuously variable transmission |
| US4976170A (en) * | 1987-08-11 | 1990-12-11 | Honda Giken Kabushiki Kaisha | Method for controlling stepless automatic transmission and apparatus therefor |
| EP0451887B1 (en) * | 1990-04-12 | 1995-06-07 | Van Doorne's Transmissie B.V. | Electronically controlled continuously variable transmission |
| GB2298907A (en) * | 1995-03-14 | 1996-09-18 | Fuji Heavy Ind Ltd | An electrohydraulic control system for a continuously-variable transmission. |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2349674A (en) * | 1999-05-01 | 2000-11-08 | Rover Group | An automatic transmission with ratio change controlled by an accelerator pedal |
| WO2005065983A1 (en) * | 2003-12-23 | 2005-07-21 | Daimlerchrysler Ag | Device equipped with a unit for actuating a continuously variable motor vehicle transmission |
| BE1021991B1 (en) * | 2014-07-28 | 2016-02-02 | Patrick Haesen | CONTINUOUS VARIABLE TRANSMISSION (CVT) AND DRIVE OF A VEHICLE FITTED WITH SUCH CVT |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9719849D0 (en) | 1997-11-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |