Multi-speed automatic vehicle transmission

Abstract

A vehicle (10) has an automatic multi-speed transmission. For starting from rest a launch ratio is selected by a slope and/or obstacle device (13, 15) according to identification of an up-slope (12), a down slope, or an obstacle (17, 18).

Claims

1. A method of selecting a launch speed ratio in a vehicle automatic transmission having a plurality of selectable speed ratios, the method comprising: detecting at least one of a slope and an obstacle, that will be encountered in the path of a vehicle, in dependence on an output of a sensing device on the vehicle looking ahead of the vehicle in a direction of intended travel, and selecting a launch speed ratio based upon at least one of a detected slope and a detected climbable obstacle.

2. A method according to claim 1, comprising: detecting an up-slope exceeding a threshold gradient; and selecting said launch speed ratio lower than a default launch speed ratio.

3. A method according to claim 1, comprising: detecting an obstacle exceeding a threshold height; and selecting said launch speed ratio lower than a default launch speed ratio.

4. A method according to claim 1, comprising: detecting a down slope exceeding a threshold gradient; and selecting said launch speed ratio lower than a default launch speed ratio.

5. A method according to claim 4, comprising: detecting a down slope exceeding a threshold gradient; and selecting a Hill Descent Control Mode that automatically controls the vehicle automatic transmission and an engine of the vehicle to control a hill descent without driver input to an accelerator pedal.

6. A method according to claim 1, comprising activating a forward or rearward sensing device in dependence on a signal indicating which one of forward and reverse motion is selected by a transmission shift selector.

7. A method according to claim 1, comprising recognizing a terrain type for the vehicle; and selecting said launch speed ratio with reference to said terrain type.

8. A method according to claim 7, comprising: recognizing a non-highway terrain type, and reducing a threshold for launch in a lower speed ratio.

9. A method according to claim 1, comprising recognizing a Hill Descent Control mode that automatically controls the vehicle automatic transmission and an engine of the vehicle to control a hill descent without driver input to an accelerator pedal; and reducing a threshold for launch in a lower speed ratio.

10. A method according to claim 1, comprising selecting an alternative range of transmission speed ratios, said alternative range including the selected launch speed ratio.

11. A method according to claim 1, wherein said sensing device comprises one of a camera device, a Radio Detection and Ranging device, and a Light Detection and Ranging device.

12. A method according to claim 1, comprising providing on the vehicle the sensing device looking in the direction of intended travel.

13. A method according to claim 1, wherein when the at least one of a detected slope and a detected climbable obstacle is not detected, a launch speed ratio higher than a default launch speed ratio is selected.

14. A method according to claim 1, comprising determining whether the detected climbable obstacle is climbable without excessive accelerator pedal movement, in preparation for at least one of a detected height of the detected obstacle and image recognition, wherein the launch speed ratio is selected in dependence on the determining.

15. A method according to claim 14, wherein the determining is dependent on whether the detected obstacle has a height lower than a curb height threshold.

16. A controller, for a vehicle automatic transmission having a plurality of selectable speed ratios, the controller being configured to carry out the method according to claim 1.

17. A vehicle having an automatic transmission, and incorporating the controller of claim 16.

18. A vehicle according to claim 17, having a forward and a rearward sensing device.

19. A vehicle according to claim 18, wherein one of the forward and rearward facing sensing devices is selectable according to a position of a transmission shift selector.

20. A non-transitory computer readable medium containing a computer program which, when run on a processor, causes at least the method according to claim 1 to be performed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) One or more embodiments of the invention will now be described, by way of example only with reference to the accompanying drawings in which:

(2) FIG. 1 illustrates schematically a vehicle with forward facing camera device and an up gradient,

(3) FIG. 2 illustrates schematically a vehicle with forward and reverse facing camera devices, and fore and aft kerbs, and

(4) FIG. 3 illustrates schematically the system of the invention.

DESCRIPTION OF EMBODIMENTS

(5) With reference to FIG. 1, a vehicle 10 is at rest on a level ground surface 11, and facing an up gradient 12. The vehicle has a forward facing camera device 13 having a field of view 14. As will be explained in more detail, the camera output is capable of being processed to recognize the up gradient 12 and to determine whether the up gradient exceeds one or more successive thresholds which may be appropriate to a lower pre-determined launch speed ratio of the vehicle transmission. The selected launch speed ratio may reduce as the up gradient increases, provided that still lower speed ratios are available for selection in the transmission.

(6) The camera device may also recognize a down gradient, and if appropriate select a higher launch ratio for a slight down gradient, but a lower launch ratio for a severe down gradient. A moderate down gradient may be suitable for a standard launch ratio, the selected launch ratio being determined by one or more gradient thresholds.

(7) Although the vehicle of FIG. 1 is illustrated on level ground, it may alternatively be on a gradient, and the output of the camera device is capable of being processed to recognize a continuance of that gradient or a change in that gradient. The output of the camera device may of course indicate level ground ahead.

(8) FIG. 2 illustrates a similar vehicle 10 at rest. The vehicle has a forward facing camera device 13 and a rearwards facing camera device 15 having a field of view 16. Respective kerbs 17, 18 are in the respective fields of view, and the output of the camera device is capable of being processed to recognize the kerbs 17, 18, and in one embodiment the height of the respective kerbs above the ground surface 11. According to appropriate thresholds, of for example, kerb height, the transmission controller selects a corresponding launch ratio to enable the kerb to be climbed without excessive accelerator pedal movement.

(9) Although illustrated on level ground in FIG. 2, the vehicle could alternatively be at rest on an up-slope or a down slope.

(10) The camera devices 13, 15 may be operative whenever the vehicle is in an ignition on condition, or may be selectively operable according to the direction of intended travel, as indicated by a forwards and reverse selector of the vehicle transmission.

(11) FIG. 3 illustrates a control system according to the invention.

(12) A vehicle engine 21 has a multi-speed automatic transmission 22 and an output shaft 23. The kind of engine and transmission is not important except that the transmission 22 is capable of selecting two or more different speed ratios for vehicle launch. The transmission may for example be a torque converter transmission having eight or more forward speed ratios. The transmission may be an all-wheel-drive transmission.

(13) A transmission controller 24 determines selection of one of several shift maps for the transmission, according to for example, an input 25 of road speed and an input 26 indicative of accelerator pedal position or torque demand. The input of road speed is from a suitable sensor 27 of road speed of the vehicle such as a wheel speed sensor of an anti-locking braking system (ABS), and may be a digital signal available from a vehicle CAN-BUS or the like. Road speed may also be calculated from instant engine speed by reference to transmission and final drive gear ratios, or from the transmission output speed by reference to the final drive gear ratio. Other inputs may be provided according to terrain type temperature, altitude and other parameters. The transmission controller described so far is of a conventional kind, and is typically implemented in and by a computer processor of the transmission or of the vehicle. The controller 24 may include a computer processor 28, and read only memory 29 for storing a plurality of transmission shift maps.

(14) According to this embodiment of the invention, the output of the camera devices 13, 15 may be processed to recognize a slope or an obstacle. Thus in one embodiment a pair of laterally spaced digital video cameras 13a, 13b are mounted at the front of a vehicle, facing forwards, and have overlapping fields of view 14a, 14b. The cameras 13a, 13b provide a stereo image capable of being processed by conventional means to determine the nature of the terrain in the field of view. For example an artificial horizon may be used to determine slope 12, or image recognition may be used to recognize a kerb 17 (or rocks or similar obstacles).

(15) Having recognized a gradient and/or an obstacle, the controller is adapted to select an appropriate launch ratio for the vehicle so that upon starting from rest the vehicle will be adapted to the terrain. In effect a suitable launch ratio is pre-selected, to the intent that normal accelerator pedal movement will be appropriate to the gradient or obstacle that the vehicle is required to overcome.

(16) In the example of FIGS. 1 and 2, a lower launch ratio may thus be selected (in forwards or in reverse); in the case of a down slope a higher launch ratio may be selected or the vehicle may launch in a ratio appropriate to level ground.

(17) The field of view of the camera device may be selected according to the vehicle and the nature of use thereof. The field of view may be ground intersecting level with the front or rear of the vehicle, may be ground intersecting within the length of the vehicle, or as illustrated be ground intersecting at a distance from the vehicle.

(18) In an embodiment of the invention, the camera device or a processor associated therewith may include a memory for remembering or recalling an obstacle. Thus in one example a kerb may be recognized immediately before parking the vehicle overnight. Upon re-start in the morning, the transmission controller may remember the obstacle by interrogating the memory, and thereby engage an appropriate launch ratio.

(19) In another example, the memory may remember an obstacle which is no longer within the field of view but is determined to be very close to the vehicle by reference to distance travelled by the vehicle. Thus a kerb hidden under a vehicle may be recalled so that vehicle launch in the opposite direction (for example after overnight parking) is in an appropriate launch speed ratio. Distance travelled may for example be determined by counting wheel rotations, and may be a standard input available on a vehicle CAN-BUS or the like.

(20) It would be appreciated that the kind of vehicle automatic transmission is not important except that the two or more different speed ratios for vehicle launch may be provided by any gear ratio configuration of any single unit or combination of units in the vehicle drive line having a plurality of selectable gear ratios. For example a transfer case with a high range and a low range is a type of vehicle automatic transmission. Selecting a launch speed ratio may comprise selecting a gear ratio in the transfer case.

(21) The output of the slope and/or obstacle sensing device may be understood to comprise a signal from a component of the sensing device indicative of the field of view in the direction of intended travel, or at least one parameter from a component of the sensing device concerning a slope and/or obstacle in the path of the vehicle, determined from the signal.

(22) Changes and modifications to the invention are envisaged within the scope of the claims appended hereto.

(23) Aspects and embodiments of the invention will be apparent from the numbered paragraphs that follow:

(24) 1. A method of selecting a launch speed ratio in a vehicle automatic transmission having a plurality of selectable speed ratios, the method comprising: providing on a vehicle a slope and/or obstacle sensing device looking in the direction of intended travel, determining the presence of a slope or the presence of an obstacle, in the path of the vehicle, and selecting a launch speed ratio appropriate to the determined slope or obstacle.

(25) 2. A method according to aspect 1 and comprising: detecting an up-slope exceeding a threshold gradient, and selecting a launch speed ratio lower than normal.

(26) 3. A method according to aspect 1 and comprising: detecting an obstacle exceeding a threshold height, and selecting a launch speed ratio lower than normal.

(27) 4. A method according to aspect 1 and comprising: detecting a down slope exceeding a threshold gradient and selecting a launch speed ratio lower than normal.

(28) 5. A method according to aspect 4 and comprising: detecting a down slope exceeding a threshold gradient and selecting a Hill Descent Control Mode.

(29) 6. A method according to aspect 1 and comprising activating said sensing device by using a transmission shift selector to select one of forward and reverse motion.

(30) 7. A method according to aspect 1 and comprising recognizing a terrain type for the vehicle, and selecting said launch speed ratio with reference to said terrain type.

(31) 8. A method according to aspect 7 and comprising: recognizing a non-highway terrain type, and reducing a threshold for launch in a lower speed ratio.

(32) 9. A method according to aspect 1 and comprising recognizing a Hill Descent Control mode and reducing a threshold for launch in a lower speed ratio.

(33) 10. A method according to aspect 1 and comprising selecting an alternative range of transmission speed ratios, said alternative range including the selected launch speed ratio.

(34) 11. A method according to aspect 1 wherein said sensing device comprises one of a camera device, RADAR and LIDAR.

(35) 12. A launch control system of a vehicle automatic transmission having a plurality of selectable speed ratios, said system comprising a plurality of transmission shift maps defining two or more launch speed ratios, a slope and/or obstacle sensing device adapted to look in the direction of intended travel and having an output, and a processor adapted to determine from said output the presence of a slope and/or an obstacle, and adapted to select a shift map appropriate to the detected slope and/or obstacle.

(36) 13. A system according to aspect 12 wherein said sensing device is a stereo camera.

(37) 14. A system according to aspect 13 wherein said stereo camera is a video camera.

(38) 15. A system according to aspect 12 wherein said sensing device provides a digital output.

(39) 16. A system according to aspect 12 wherein said processor is adapted to determine the value of a slope and/or the height of an obstacle.

(40) 17. A system according to aspect 12 incorporated within a vehicle having an automatic multi-speed transmission.

(41) 18. A vehicle having a forward and a rearward sensing device, and a launch control system of a vehicle automatic transmission having a plurality of selectable speed ratios, said system comprising a plurality of transmission shift maps defining two or more launch speed ratios, said sensing device being adapted to look in the direction of intended travel and having an output, and said vehicle comprising a processor adapted to determine from said output the presence of a slope and/or an obstacle, and said being adapted to select a shift map appropriate to the detected slope and/or obstacle.

(42) 19. A vehicle according to aspect 18 wherein one of the forward and rearward facing sensing devices is selectable according to the position of a transmission shift selector.