CLIAMS:We claim:
1. A clutch controller (100) for a vehicle with semi-automatic transmission, said controller adapted to:
detect occurrence of at least one shift indicating event related to gear shift,
compute a shift probability value based on detected at least one shift indicating event,
receive current engine torque (108) upon detection of said at least one shift indicating event, and
vary the distance between clutch plates of said clutch (102) in accordance to said engine torque (108) and said shift probability value.
2. The clutch controller (100) as claimed in claim 1, wherein said shift indicating event is detected to be occurred based on a status of at least one shift indicating parameter selected from a group comprising vehicle speed, vehicle gradient, road surface, engine speed, actual engine torque (108), accelerator pedal position, brake pedal position, rate of change of accelerator pedal position and brake pedal position, a rate of change of rotation of steering wheel.
3. The clutch controller (100) as claimed in claim 1, wherein said shift probability value is calculated in percentage based on number of shift indicating events detected.
4. The clutch controller (100) as claimed in claim 1, wherein the distance between said clutch plates is varied in such a manner that the torque transmitting capacity of the clutch (102) is maintained at a capacity equal to or greater than a current engine torque (108).
5. The clutch controller (100) as claimed in claim 1, wherein a variation of shift probability value is a filtered output of variation in at least one shift indicating event.
6. A method for controlling clutch (102) for a vehicle with semi-automatic transmission, said method comprises the steps of:
detecting at least one shift indicating event related to gear shift,
computing shift probability value based on detected at least one shift indicating event,
measuring engine torque (108) upon detection of said at least one shift indicating event, and
varying the distance between clutch plates of said clutch (102) in accordance to said engine torque (108) and said shift probability value.
7. The method as claimed in claim 6, wherein said shift indicating event is detected to be occurred based on a status of at least one shift indicating parameter selected from a group comprising vehicle speed, vehicle gradient, road surface, engine speed, actual engine torque (108), accelerator pedal position, brake pedal position, rate of change of accelerator pedal position and brake pedal position, a rate of change of rotation of steering wheel.
8. The method as claimed in claim 6, wherein said shift probability value is calculated in percentage based on number of shift indicating events detected.
9. The method as claimed in claim 6, wherein varying the distance between clutch plates is performed to maintain the clutch torque equal or greater than the current engine torque (108).
10. The method as claimed in claim 6, wherein said clutch plates are disengaged based on an actual gear shift request by an operator.
,TagSPECI:Field of the invention:
[0001] The present disclosure relates to a controller or processor to automatically control a clutch for a vehicle with semi automatic transmission.
Background of the invention:
[0002] According to a patent literature US8306714, a start permission decision section issues a start permission when an engine speed and a throttle valve opening become higher than predetermined values. A clutch-torque capacity storage section stores a clutch-torque capacity reference map in which a clutch-torque capacity is set as a function of at least the engine speed or as a function of the engine speed and the throttle valve opening. A clutch-torque capacity correction section corrects the clutch-torque capacity reference map so that the clutch-torque capacity is proportionally reduced in response to the difference between the engine speed and a start permission speed when start permission is issued. An oil pressure controlling section connects the clutch with the clutch-torque capacity obtained in accordance with the corrected clutch-torque capacity map to start the vehicle.
Brief description of the accompanying drawings:
[0003] An embodiment of the disclosure is described with reference to the following accompanying drawings,
[0004] Fig. 1 illustrates a block diagram of a clutch controller, for a vehicle with semi-automatic transmission, according to an embodiment of the present disclosure,
[0005] Fig. 2 illustrates a method of controlling the clutch through a graphical representation, according to an exemplary embodiment of the present disclosure, and
[0006] Fig. 3 illustrates a method for controlling a clutch for a vehicle with semi-automatic transmission, according to an embodiment of the present disclosure.
Detailed description of the embodiments:
[0007] Fig. 1 illustrates a block diagram of a clutch controller, for a vehicle with semi-automatic transmission, according to an embodiment of the present disclosure. The clutch controller 100 is adapted to detect occurrence of at least one shift indicating event related to gear shift, compute a shift probability value based on detected at least one shift indicating event, receive current engine torque 108 upon detection of the at least one shift indicating event, and vary the distance between clutch plates of the clutch 102 in accordance to the current engine torque 108 and the shift probability value.
[0008] The engine torque 108 is measured at clutch 102. Alternatively, an inner engine torque 108 or a crankshaft engine torque 108 is measured.
[0009] The clutch controller 100 is a processor or an Electronic Control Unit (ECU) with conventional input ports, storage means, output ports, other interfacing means and the like. The clutch controller 100 receives input signals 106 from the plurality of shift indicating parameters indicated by multiple arrows. The shift indicating parameters are monitored/ measured by respective on-board sensors or vehicle’s main control unit. The clutch controller 100 communicates with the memory element 104 which stores information comprising threshold value table 1046 or conditions for plurality of shift indicating parameters, an adaptation table/curve 1044 for the clutch 102 and control characteristics 1042 of the clutch 102. The clutch controller 100 receives the real time input signal 106 of at least one shift indicating parameter and compares with the respective threshold value stored in the memory element 104. Alternatively, the clutch controller 100 receives real time input signals 106 for plurality of shift indicating parameters and compares the threshold values of two or more of shift indicating parameters at a time. The information stored in the memory element 104 is configurable and allowed to be changed as per the requirement.
[00010] The semi-automatic transmission is selected from a group comprising an automated manual transmission, clutch-pedal less manual transmission, electronic clutch (e-clutch) manual transmission, a manual transmission with automatic clutch control. The clutch 102 is controlled (disengaged, engaged) by the use of an actuator with the inputs from the sensors monitoring the movement of the gear lever movement.
[00011] The clutch 102 is actuated by any one selected from a group comprising hydraulic, pneumatic, electromagnetic, electromechanical and the like.
[00012] The at least one shift indicating event is considered or detected to be occurred/triggered based on the status of at least one shift indicating parameter. The detection of shift indicating events comprise checking whether the input signals 106 of the shift indicating parameters is present/available or absence/ unavailable or crosses respective set threshold value. The shift indicating parameter broadly comprises vehicle parameters, engine parameters, and driver inputs. Specifically, the vehicle parameter comprises vehicle speed, vehicle gradient, road surface and the like. The engine parameter comprises speed, torque, temperature, drive condition and the like. The drive condition further comprises uphill, downhill, coasting, overtake, normal drive and the like. The other parameter which triggers a shift indicating event comprises enable conditions, Gear Shift Timing (GST) and the like. The GST corresponds to the up-shift and downshift indication. The enable conditions are evaluated to enable the gear shift prediction process. The various enable conditions comprises, no system errors present, brake has not been pressed for certain duration, certain time has elapsed since the last gear shift, driver assistance features like cruise control are enabled or not enabled and the like. The GST is calculated in different ways comprising speed based or torque based. The driver inputs corresponds to driver demands in terms of position of accelerator pedal or brake pedal, rate of change of press or release of accelerator pedal and brake pedal, rate of change of rotation of steering wheel, and the like.
[00013] Each of the shifts indicating parameters are considered independently. Alternatively, a combination of two or more shift indicating parameters is considered together for triggering a shift indicating event. Alternatively, at least one shift indicating parameter is considered first (prioritized) and on satisfying that, other shift indicating parameters are monitored.
[00014] Due to multiple inputs and road conditions, the possibility of multiple drive conditions to be true at given point of time exists. Hence, drive conditions are prioritized in multiple drive conditions. Based on the prioritized drive conditions, different thresholds (for engine speed, vehicle speed and torque and other shift indicating parameters) are selected for calculating the shift probability.
[00015] Once the threshold values are selected based on the prioritized driving conditions, the shift probability is calculated when the vehicle parameters, or engine parameters or driver inputs cross their respective thresholds. Based on the status of the shift indicating parameters the corresponding shift indicating event is considered to be occurred and hence is taken forward for calculating the shift probability of the transmission. The greater the number of shift indicating parameters reaching respective threshold values, the more the number of shift indicating event occurring and hence increasing the shift probability of the gear change. Similarly, when the shift indicating parameters no longer satisfies the threshold condition or value, the respective shift indicating event is also eliminated or reduced. Hence, there is reduction in shift probability.
[00016] The shift probability is calculated as and when a shift indicating event is triggered. The clutch controller 100 computes the shift probability in terms of percentage values based on number of shift indicating events detected. The percentage values are normalized for fast calculation and filtered for proper control. Based on the calculated shift probability value, the clutch controller 100 accesses the memory element 104 for the adaptation table/curve 1044.
[00017] Based on the calculated shift probability an adaptation table 1044 to compute an appropriate clutch torque is used. The adaptation table 1044 represents a set of values (a multiplier) against the respective shift probability values. Thus, based on a specific shift probability value the corresponding adaptation value is selected from the table. The clutch controller 100 then reads the current engine torque 108 and multiplies with the adaptation value to obtain a required clutch torque. The clutch 102 is maintained at the calculated clutch torque value. i.e. the distance between the clutch plates of the clutch 102 is varied such that the clutch 102 is able to transmit the calculated clutch torque. The adaptation value is dynamically selected by the clutch controller 100.
[00018] The variation of shift probability value is a filtered output of variation in at least one shift indicating event.
[00019] Based on the calculated clutch torque, the clutch controller 100 controls the clutch actuator to vary the distance between the clutch plates and maintain the required clutch torque. The distance between the clutch plates is varied in such a manner that the torque transmitting capacity of the clutch 102 is maintained at a capacity equal to or greater than the engine torque 108. The torque transmitting capacity signifies the torque which the clutch 102 is able to transfer/transmit to the transmission.
[00020] The clutch plates are disengaged based on an actual gear shift request by an operator. The operator moves the gear shift lever to change gear. Since the clutch 102 is maintained at a torque equal to the engine torque 108 during high shift probability, and slightly greater than engine torque 108 during subsequent lower shift probability, when the actual gear shift request is received by the clutch controller 100, the gear shift is smooth without any resistance at the gear lever or notch feeling.
[00021] Fig. 2 illustrates a method of controlling the clutch through a graphical representation, according to an exemplary embodiment of the present disclosure. The graph comprises two axes where the X-axis 202 represents time and Y-axis 204 represents shift probability in percentage and torque in Nm. A curve 206 represents shift probability calculated by the clutch controller 100 based on triggering of at least one shift indicating event. A curve 208 represents required clutch torque calculated by the clutch controller 100. A curve 210 represents engine torque 108. For the curve 206, the Y-axis represents shift probability, and for the curve 208 and 210 the Y-axis represents torque.
[00022] Now, consider as an example, the maximum engine torque 108 (engine peak torque) for a vehicle is 70Nm and the engine torque 108 is maintained at 30Nm shown by the curve 210 with minor fluctuations. Consider a maximum clutch torque capacity is 150Nm with the factor of safety, and as shown in Fig. 2 at the beginning of the curve 208 it is maintained at 150Nm. If any one of the shift indicating parameters satisfies respective threshold condition/value, a shift indicating event is triggered, thereby increasing the shift probability. The phase/stage 2042 shows occurrence of a shift indicating event and hence increases the shift probability. As the shift probability curve 206 rises, a corresponding decrease in clutch engagement is performed by the clutch controller 100 as shown in the curve 208 by reducing the clutch transfer torque, at time interval 2022. At another time interval 2024, one or more shift indicating events has triggered which is shown by phase 2044; hence a corresponding decrease in clutch coupling is performed as shown by fall of curve 208. Similarly at time interval 2026 and 2028, a set of other shift indicating event triggers shown by phase 2046 and 2048, which results in corresponding fall of clutch torque curve. After the phase 2048, the shift probability is very high and clutch torque is maintained at 40Nm slightly greater than the engine torque 30 Nm to facilitate easy clutch disengagement when the gear shift lever is moved by the operator.
[00023] At each shift probability a value from adaptation table 1044 is taken and multiplied with the engine torque 108 measured at that instant of time. The result of multiplication is the required clutch torque. The fall or drop in the clutch torque curve 208 represents reduction in the distance between the clutch plates so that the clutch 102 is coupled with some slip with a reduced torque transmitting capacity. The closer the clutch torque is to the engine torque 108, the lesser the time required to change the gear after an actual gear shift request.
[00024] According to an embodiment of the present disclosure, a clutch controller 100 is provided to track the engine torque 108 and accordingly maintain the engagement degree of the clutch plates of the clutch 102. Alternatively, the clutch controller 100 tracks the engine torque 108 based on fulfillment of selected shift indicating events.
[00025] According to an embodiment of the present disclosure, a clutch controller 100 is provided in which the probability calculation is based on one of the shift indicating event which is based on the rate of press and/or release of the accelerator pedal and/or brake pedal. For example: the clutch controller 100 calculates a shift probability when accelerator pedal is released at a rate greater than respective threshold provided that certain prioritized shift indicating event has occurred.
[00026] The shift indicating event is detected to be occurred based on a status of at least one shift indicating parameter selected from a group comprising vehicle speed, vehicle gradient, road surface, engine speed, actual engine torque 108, accelerator pedal position, brake pedal position, rate of change of accelerator pedal position and brake pedal position. The shift probability value is calculated in percentage based on number of shift indicating events detected and is further normalized for efficient and faster processing.
[00027] Due to the implementation of the said invention, while shifting the notch or feeling of resistance to move is eliminated as the clutch 102 is already opened to position where the clutch torque and engine torque 108 are almost identical. After certain duration (variable amount of time) of torque tracking, if a gear shift does not happen, torque tracking is disabled.
[00028] Fig. 3 illustrates a method for controlling a clutch for a vehicle with semi-automatic transmission, according to an embodiment of the present disclosure. The method comprises the step 302 comprising detecting at least one shift indicating event related to the gear shift. The step 304 comprises computing shift probability value based on detected at least one shift indicating event. The step 306 comprises measuring engine torque 108 upon detection of the at least one shift indicating event. The step 308 comprises varying the distance between clutch plates of the clutch 102 in accordance to the engine torque 108 and the shift probability value.
[00029] The varying of the distance between clutch plates is performed to maintain the clutch torque equal or greater than the engine torque 108. The clutch plates are disengaged based on an actual gear shift request by the operator.
[00030] According to an embodiment of the present disclosure, a multistage torque tracking is made possible based on the probability levels calculated and hence reducing the resistance during gear shifts. The clutch controller 100 provides improvement in clutch actuation and hence faster response. Based on the probability shift, the driver is suggested via a Human Machine Interface (HMI) display to do a gear shift. The clutch controller 100 also demands less peak current drawn by clutch actuator while shifting thereby reducing power consumption. The loads on the actuator are very less, and hence better clutch 102 and actuator life. The clutch controller 100 achieves a robust torque tracking.
[00031] In a two pedal e-clutch system, torque tracking is necessary for faster response of the system while gear shifting. The clutch controller 100 activates the torque tracking only when preliminary checks are validated and hence avoids keeping the clutch 102 in torque tracking position where the actuator consumes power. The clutch controller 100 also handles the multi stage torque tracking based on probability calculation where the clutch actuator is not always kept in actuated state.
[00032] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.