CONTROL MODULE

Abstract

The present invention relates to a control module (62) for controlling an automatic gearbox (58). The control module comprises (62) a monitoring module (70) for monitoring one or more parameters of at least one powertrain element. The control module (62) also comprises a determining module arranged to determine a temperature of a powertrain component based on said one or more monitored parameters. The control module (62) also comprises a driving module (60) arranged to detect a driving condition of the vehicle. The control module (62) also comprises an output module (74) arranged to output a downshift command (76) to the automatic gearbox (58) in dependence on the driving condition of the vehicle and on the temperature of the powertrain component exceeding a predetermined threshold, wherein the downshift command selects a gear higher than first gear.

Claims

1-31. (canceled)

32. A control module for controlling an automatic gearbox, the control module comprising; a monitoring module for monitoring one or more parameters of at least one powertrain element; a determining module arranged to determine a temperature of a powertrain component based on said one or more monitored parameters; a driving module arranged to detect a driving condition of the vehicle and select a specific gear based on the driving condition; and an output module arranged to output the specific gear to the automatic gearbox, and further arranged to output a downshift command to the automatic gearbox in dependence on the driving condition of the vehicle and on the temperature of the powertrain component exceeding a predetermined threshold, wherein the downshift command selects a gear higher than first gear.

33. The control module of claim 32, wherein the predetermined threshold is selected in dependence on the detected driving condition of the vehicle.

34. The control module of claim 32, wherein the driving condition includes one or more of; a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type.

35. The control module of claim 32, wherein the powertrain component is at least one of a torque converter element and a torque converter element including a torque converter fluid.

36. The control module of claim 32, wherein the determining module is arranged to determine the temperature indirectly by modelling the temperature of the powertrain component wherein the one or more parameters does not include temperature of the powertrain component.

37. The control module of claim 32, wherein at least one of: (i) the at least one powertrain element is selected from a torque converter, a torque converter turbine, a torque converter impeller, a lock-up clutch, a torque converter fluid, a transmission system hydraulic fluid, and a fluid sump; and (ii) the at least one parameter is selected from a torque converter turbine speed, a torque converter turbine torque, a lock up clutch setting, a torque converter fluid pressure, a transmission system hydraulic pressure, a bulk fluid temperature at the sump, and torque converter slip speed.

38. A control module for controlling an automatic gearbox, the control module comprising; a monitoring module for monitoring one or more parameters of at least one powertrain element; a determining module arranged to determine a temperature of a powertrain component based on said one or more monitored parameters; a driving module arranged to detect a driving condition of the vehicle and select a specific gear based on the driving condition, wherein the driving condition is indicative of a likelihood of the vehicle composure being compromised by executing a down shift in the automatic gearbox; and an output module arranged to output a downshift command to the automatic gearbox in dependence on the driving condition of the vehicle and on the temperature of the powertrain component exceeding a predetermined threshold, wherein the downshift command selects a gear higher than first gear in dependence on the driving condition.

39. The control module of claim 38, wherein the output module is configured to inhibit the output of the downshift command in dependence on the detected driving condition of the vehicle.

40. The control module of claim 38, wherein the predetermined threshold is selected in dependence on the detected driving condition of the vehicle.

41. The control module of claim 38, wherein the driving condition includes one or more of a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type.

42. A transmission system for a vehicle comprising an automatic gearbox and the control module of claim 32.

43. A vehicle comprising the transmission system of claim 42.

44. A method of controlling an automatic gearbox, comprising; monitoring one or more parameters of at least one powertrain element; determining a temperature of a powertrain component based on said one or more monitored parameters; detecting a driving condition of the vehicle; selecting a specific gear based on the driving condition; and outputting a downshift command to the automatic gearbox in dependence on the driving condition of the vehicle and on the temperature of the powertrain component exceeding a predetermined threshold, wherein the downshift command selects a gear higher than first gear.

45. The method of claim 44, wherein selecting the predetermined threshold is in dependence on the detected driving condition of the vehicle.

46. The method of claim 44, wherein the powertrain component is at least one of a torque converter element and a torque converter element including a torque converter fluid.

47. The method of claim 44, wherein determining the temperature of the powertrain component includes; modelling the temperature of the powertrain component wherein the one or more parameters does not include temperature of the powertrain component.

48. The method of claim 44, wherein at least one of: (i) the at least one powertrain element is selected from a torque converter, a torque converter turbine, a torque converter impeller, a lock-up clutch, a torque converter fluid, a transmission system hydraulic fluid, and a fluid sump; and (ii) the at least one parameter is selected from a torque converter turbine speed, a torque converter turbine torque, a lock up clutch setting, a torque converter fluid pressure, a transmission system hydraulic pressure, a bulk fluid temperature at the sump, and torque converter slip speed.

49. The method of claim 44, wherein the driving condition includes one of; a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type.

50. A method of controlling an automatic gearbox, comprising; monitoring one or more parameters of at least one powertrain element; determining a temperature of a powertrain component based on said one or more monitored parameters; detecting a driving condition of the vehicle, wherein the driving condition is indicative of a likelihood of the vehicle composure being compromised by executing a down shift in the automatic gearbox; selecting a specific gear based on the driving condition; and outputting a downshift command to the automatic gearbox in dependence on the driving condition of the vehicle and on the temperature of the powertrain component exceeding a predetermined threshold.

51. The method of claim 50, comprising at least one of inhibiting outputting the downshift command in dependence on the detected driving condition; the downshift command selects a gear higher than first gear in dependence on the driving condition; and selecting the predetermined threshold in dependence on the detected driving condition of the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0070] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0071] FIG. 1 shows a schematic of a vehicle including a control module according to the present invention;

[0072] FIG. 2 shows an exploded perspective view of a torque converter from FIG. 1;

[0073] FIG. 3 shows a transmission system from FIG. 1; and

[0074] FIG. 4 shows the control module from FIG. 1.

DETAILED DESCRIPTION

[0075] With reference to FIG. 1, a vehicle 10, such as a car, includes a chassis 12 for supporting various components and systems such as a set of four wheels 13 and a powertrain 14 for powering the wheels.

[0076] The powertrain 14 includes an engine 16 having an output shaft coupled to a torque converter 18, an oil sump 19, a transmission system 20, a transmission system hydraulic fluid 21, a transfer box 22, a prop-shaft 24, front and rear differential gears 26, 28, and front and rear drive shafts 30, 32.

[0077] With reference to FIG. 2, the torque converter 18 includes an impeller 34 driven by the engine output shaft (not shown). The impeller 34 includes an interior face 36 supporting a plurality of impeller blades 38. The torque converter also includes a cover 40 attached to the impeller 34 by welding. The cover has a projecting bearing 42 allowing access for the engine output shaft. The torque converter also includes a turbine 44. The turbine 44 has a plurality of turbine blades (not shown) on an interior face 46.

[0078] The torque converter 18 also includes a stator 50. The stator 50 includes a plurality of stator blades 52 forming an annular ring within which the one way clutch 48 fits. The stator blades 52 have a relatively high angle of attack to fluid flow travelling in the direction of rotation of the impeller 34 and turbine 44. The stator 50 has two functions. During low speed, the stator 50 is locked to restrict movement, redirecting the fluid expelled by the turbine 44 back into the impeller 34 with the use of its blades. This results in torque amplification. At high speed, the stator 50 becomes free and allows fluid to pass easily into the impeller 34, therefore enhancing efficiency.

[0079] The torque converter 18 also includes a one way clutch. The one way clutch 48 prevents the stator 50 from moving in both directions. The stator 50 assembly must be prevented from rotating in one direction in order to amplify the torque.

[0080] A fluid, namely oil, is provided within the torque converter 18. This oil forms a circuit which includes the oil sump 19 (FIG. 1). When the engine 16 is running, the engine output shaft (not shown) rotates thus rotatably driving the impeller 34. The oil is propelled by the impeller 34 to flow axially along an axis of rotation (A) of the torque converter towards the turbine 44. The oil flow causes an induced flow of the turbine 44 by driving the turbine blades. The turbine is connected to a transmission shaft 45 (FIG. 3) of the transmission system 20. Rotation of the turbine 44 thus causes the same speed of rotation of the transmission shaft 45. There is a difference in speeds between the engine shaft and the transmission shaft 45 due to the fluid coupling of the impeller 34 and the turbine 44. This difference in speeds is known as the slip speed of the torque converter 18. This slip speed results in amplification in torque between the engine output shaft and the transmission shaft 45. Low gear, or low vehicle speed, together with high engine output shaft speed results in a high slip speed and high amplification in torque. The slip speed, and resulting torque amplification, reduces with increasing vehicle speed. It is the high slip speed which results in excessive temperatures of the torque converter 18 since the oil is being worked hard at high slip speeds.

[0081] A return flow of oil passing between the turbine 44 and the impeller 34 also passes through the stator blades 52. The high angle of attack of the stator blades 52 deflects the oil sufficiently to reduce the resistance of the impeller 34.

[0082] The torque converter 18 also includes a lock up clutch 54. The lock up clutch 54 is connected to both the impeller 34 and the turbine 44. The lock up clutch 54 has several settings. One setting is ‘open’ whereby no resistance to slip is provided between the impeller 34 and the turbine 44. A setting at the other extreme is ‘closed’ whereby the impeller 34 is locked relative to the turbine 44 preventing any slip speed since the two components are mechanically coupled together as opposed to being fluidly coupled together. There are also several graduated degrees of resistance between respective ‘open’ and ‘closed’ settings each providing an increasing degree of resistance to slip of the turbine relative to the impeller. The lock up clutch is particularly useful for high speed driving when no torque amplification is desired and the existence of slip speed results in a degradation in fuel economy.

[0083] With reference to FIG. 3, the transmission system 20 includes an automatic gearbox 58 which is coupled to the turbine 44 of the torque converter 18 by the transmission shaft 45. The automatic gearbox 58 includes a planetary gear arrangement. The gears are shifted by hydraulic pressure for the transmission system hydraulic fluid 21.

[0084] The transmission system also includes a driving module 60 and a control module 62. The driving module 60 and control module 62 are provided as electrical data on a non-transitory memory component of the vehicle's computer system. The computer system also includes one or more processors for executing the respective modules.

[0085] The driving module 60 is arranged to receive various inputs 64 from sensors and/or other modules of the vehicle. These inputs 64 indicate various vehicle conditions to the driving module 60. These vehicle conditions include a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type. The driving module 60 is arranged to detect a driving condition of the vehicle 10 and configures the automatic gearbox 58 to select a specific gear based on the driving conditions. For instance, a weather condition such as snow or ice being detected on the ground might result in the driving module configuring the gearbox 58 to select a higher than normal gear for a current vehicle speed. For a stationary vehicle in this case, the gearbox 58 might configure the gearbox 58 to select a gear other than first for commencing driving, or vehicle move off. In this case, the move off gear may be second gear.

[0086] Still with reference to FIG. 3, the control module 62 is arranged to receive inputs from various sensors 66 and/or other modules of the vehicle 10. These sensors 66 are positioned throughout the powertrain 14 on various elements thereof, those elements including components and sub-systems of the powertrain 14. The powertrain elements are selected from the list of the torque converter 18, the torque converter turbine 44, the torque converter impeller 34, the lock-up clutch 54, the torque converter fluid or oil, the transmission system hydraulic fluid 21, and the fluid sump 19.

[0087] The parameters which the various sensors 66 measure include the torque converter turbine 44 speed, the torque converter turbine 44 torque, the lock up clutch 54 setting, the torque converter 18 fluid pressure, the transmission system hydraulic 21 pressure, the bulk fluid temperature at the sump 19, and torque converter 18 slip speed. The actual sensors 66 are known in the art and are described in no great detail here.

[0088] With reference to FIG. 4, the control module 62, for controlling the automatic gearbox 58 (FIG. 3), comprises a monitoring module 70, a determining module 72, and an output module 74.

[0089] The monitoring module 70 is communicatively linked to the sensors 64 (FIG. 3). The monitoring module 70 can thus monitor the one or more parameters of any of the elements of the powertrain 14. Specifically, the monitoring module 70 can monitor the torque converter turbine 44 speed, the torque converter turbine 44 torque, the lock up clutch 54 setting, the torque converter 18 fluid pressure, the transmission system hydraulic 21 pressure, the bulk fluid temperature at the sump 19, and torque converter 18 slip speed.

[0090] The determining module 72 determines a temperature of the torque converter 18 fluid indirectly by modeling said temperature based on the torque converter turbine 44 speed, the torque converter turbine 44 torque, the lock up clutch 54 setting, the torque converter 18 fluid pressure, the transmission system hydraulic 21 pressure, the bulk fluid temperature at the sump 19, and torque converter 18 slip speed. In this way, the temperature of the torque converter fluid is determined indirectly based on parameters other than the temperature of the torque converter fluid itself. This is advantageous since the other parameters are being monitored by other systems for other purposes and so they can be used here for torque converter fluid temperature determination rather than including another sensor to measure the temperature of the torque converter fluid directly.

[0091] The output module 74 compares the modeled temperature of the torque converter 18 fluid to a predetermined temperature threshold. The predetermined temperature threshold is indicative of a fluid temperature which could result in fluid degradation or failure of the one of the torque converter 18 elements, namely the impeller 34, the turbine 44, the stator 50, etc. The predetermined temperature threshold is between 180° C. and 300° C., with 180° C. being the predetermining temperature for most fluids used by torque converters 18.

[0092] The output module 74 then outputs a downshift command 76 to the automatic gearbox in response to the temperature of the torque converter 18 fluid exceeding the predetermined threshold. As mentioned above, the highest temperatures experienced by the torque converter 18 fluid are usually when the driving module 60 has configured the gearbox 58 to select a gear higher than first gear for low vehicle speeds such as when the vehicle moves off from stationary, in addition to the driver using excess throttle input. A downshift in gear to first gear results in the slip speed across the torque converter 18 reducing since wheel torque is reduced by selecting a lower gear. When in first gear, the turbine 44 will run slower than when the gearbox is in second gear. This reduction in slip speed reduces the frictional burden on the fluid circulation velocity resulting in a reduction in temperature.

[0093] Various modifications can be made to this invention without falling outside of the scope of the subsequent claims. Some of these modifications, or alternative embodiments, are outlined in more detail below. Those features of the subsequent embodiments which are in common with the first embodiment are not repeated for brevity.

[0094] In one alternative embodiment, the sensor 166 (FIG. 3) is a thermocouple directly measuring the fluid temperature within the torque converter 118 (FIG. 2). With reference to FIG. 4, the determining module 172 determines the fluid temperature directly based on the thermocouple sensor 166 readings monitored by the monitoring module 170. The output module 174 is again arranged to output a downshift command 174 to the automatic gearbox in response to the temperature of the fluid exceeding the predetermined threshold.

[0095] In another alternative embodiment, a temperature of a powertrain component other than the torque converter fluid is determined. For example, the temperature of the gearbox could be determined using the same invention by monitoring one or more parameters of at least one powertrain element; determining a temperature of a powertrain component based on the monitored parameter; and outputting a downshift command to the automatic gearbox in response to the temperature exceeding a predetermined threshold. The predetermined threshold would change in according to a likely failure temperature associated with that component. For example, the temperature at which the gearbox fails might be different to 180° C.

[0096] As with the first embodiment, the temperature of the powertrain component can be determined indirectly by modeling the temperature of the powertrain component where the one or more parameters used to model said temperature does not include temperature of the powertrain component itself.

[0097] Further aspects of the present invention are set out in the following numbered Clauses:

Clause 1: A control module for controlling an automatic gearbox, the control module comprising; [0098] a monitoring module for monitoring one or more parameters of at least one powertrain element; [0099] a determining module arranged to determine a temperature of a powertrain component based on the monitored parameter; and [0100] an output module arranged to output a downshift command to the automatic gearbox in response to the temperature exceeding a predetermined threshold.
Clause 2: The control module of Clause 1 wherein the powertrain component is a torque converter element.
Clause 3: The control module of Clause 2 wherein the torque converter element includes a torque converter fluid.
Clause 4: The control module of Clause 1 wherein the determining module is arranged to determine temperature indirectly by modelling the temperature of the powertrain component wherein the one or more parameters does not include temperature of the powertrain component.
Clause 5: The control module of Clause 1 wherein the at least one powertrain element is selected from the list of a torque converter, a torque converter turbine, a torque converter impeller, a lock-up clutch, a torque converter fluid, a transmission system hydraulic fluid, and a fluid sump.
Clause 6: The control module of Clause 5 wherein the at least one parameter is selected from the list of a torque converter turbine speed, a torque converter turbine torque, a lock up clutch setting, a torque converter fluid pressure, a transmission system hydraulic pressure, a bulk fluid temperature at the sump, and torque converter slip speed.
Clause 7: A transmission system for a vehicle comprising an automatic gearbox and the control module of Clause 1.
Clause 8: The transmission system of Clause 7 further comprising a driving module arranged to detect a driving condition of the vehicle and configure the automatic gearbox to select a gear higher than first gear based on the driving condition.
Clause 9: The transmission system of Clause 8 wherein the driving condition includes one or more of; a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type.
Clause 10: A vehicle comprising the transmission system of any of Clause 7.
Clause 11: A method of controlling an automatic gearbox, comprising; [0101] monitoring one or more parameters of at least one powertrain element; [0102] determining a temperature of a powertrain component based on the one or more monitored parameters; and [0103] outputting a downshift command to the automatic gearbox in response to the temperature exceeding a predetermined threshold.
Clause 12: The method of Clause 11 wherein the powertrain component is a torque converter element.
Clause 13: The method of Clause 12 wherein the torque converter element includes a torque converter fluid.
Clause 14: The method of any of Clause 11 wherein determining the temperature of the powertrain component includes; [0104] modeling the temperature of the powertrain component wherein the one or more parameters does not include temperature of the powertrain component.
Clause 15: The method of Clause 11 wherein the at least one powertrain element is selected from the list of a torque converter, a torque converter turbine, a torque converter impeller, a lock-up clutch, a torque converter fluid, a transmission system hydraulic fluid, and a fluid sump.
Clause 16: The method of Clause 15 wherein the at least one parameter is selected from the list of a torque converter turbine speed, a torque converter turbine torque, a lock up clutch setting, a torque converter fluid pressure, a transmission system hydraulic pressure, a bulk fluid temperature at the sump, and torque converter slip speed.
Clause 17: The method of Clause 11 comprising; [0105] detecting a driving condition of the vehicle; and [0106] configuring the automatic gearbox to select a gear higher than first gear based on the driving condition, prior to outputting the downshift command to the automatic gearbox.
Clause 18: The method of Clause 17 wherein the driving condition includes one of; a driving program setting, an accelerator position, a brake position, a vehicle speed, a vehicle acceleration, a vehicle orientation, a weather type, and a surface type.