Overrun control device in an automatic transmission vehicle

Abstract

Overrun control device (100) in an automatic transmission vehicle (AG vehicle), wherein the AG vehicle comprises a starter motor (50) coupled to the engine (200) and an engine control means (250) which, depending on an overrun state (201) of the engine (200), causes a decoupling of the engine from a transmission (300) of the AG vehicle, wherein the overrun control device (100) is characterized by - a prediction means (10) for determining a start of the overrun operating state (201), activating the engine control means (250) and predicting a duration (D) of the overrun operating state (201); - a comparator (20) for comparing the predicted duration (D) of the overrun operating state (201) with a duration (OTD) required to carry out at least one predetermined test (211) in the overrun operating state (201), and - a switching means (30) for selectively driving the prime mover (200) using the starter motor (50) and carrying out the at least one predetermined test (211) during the overrun operating state (201) as a function of the comparison (21) by the comparator (20).

Description

Field of the InventionThe present invention relates to an overrun control device in an automatic transmission (AT) vehicle for controlling an engine of the AT vehicle during an overrun condition.BACKGROUND OF THE INVENTIONAn coasting state of an automatic transmission (AG) vehicle is a state in which there is no request for an engine torque of the vehicle and the vehicle travels due to the forward kinetic energy of the vehicle. In such a coasting state, the vehicle's engine could be shut down and decoupled from the vehicle's transmission, so that the engine drag torque is reduced and the vehicle could continue to move with the vehicle's kinetic propulsion energy.However, the engine cannot be shut down and decoupled under all circumstances of an overrun operating condition. Several predetermined tests, diagnostic functions, and correction functions such as correcting long term drift of fuel injection into the engine, compensation for cylinder specific torque variation, correction of segment times to determine engine speed from the engine speed sensor, lambda sensor offset correction or NOx sensor offset correction function tests, NOx sensor and lambda sensor diagnostics are performed during the coasting mode. These predetermined tests require the engine to run without shutdown.Patent application WO 2013 / 104 617 A1 teaches a technology for reducing fuel consumption during coasting by decoupling the engine from the transmission of the vehicle, but without shutting down the engine.Furthermore, DE 10 2011 076 165 B4 describes a method for diagnosing an internal combustion engine of a motor vehicle, wherein the internal combustion engine is designed to provide power for driving the motor vehicle or for storage in an energy store. The motor vehicle has an electric machine which, for setting different operating states, generates a torque acting on a crankshaft of the internal combustion engine, which torque can be positive according to the embodiment. The internal combustion engine is at least temporarily separated from a drive train of the motor vehicle, while the torque is generated by the electric machine.DESCRIPTION OF THE INVENTIONThe present invention is an overrun control device in an automatic transmission (AT) vehicle for operating an engine of the vehicle during an overrun condition of the vehicle. The AG vehicle includes a starter motor coupled to the engine, an engine control means for disabling the engine in dependence on a coasting state of the engine and for decoupling the engine from a transmission of the AG vehicle.The coasting control device of the present invention is characterized in that prediction means determines a start of the coasting, activates the engine control means, and predicts a duration of the coasting at the start of the coasting. A comparator compares the predicted duration of the coasting state with a duration required to perform at least one predetermined test in the coasting state. Switching means of the coasting control device selectively drives the engine in response to the comparison by the comparator using the starter motor and performs the at least one predetermined test during the coasting state.The coasting control apparatus of the present invention is advantageous in that the predicting means activates the engine control means for disengaging the engine of the vehicle from the transmission of the vehicle when the vehicle enters the coasting state. The engine is decoupled by the coasting controller regardless of whether or not the at least one predetermined test would be performed in the coasting state of the vehicle. The predetermined test is correction of long term drift of fuel injection into the engine, compensation for cylinder specific torque variation, correction of segment times to determine engine speed from the engine speed sensor, lambda sensor offset correction or NOx sensor offset correction function tests, NOx sensor and lambda sensor diagnostics. Thus, thanks to the advantageous features of the coasting control device of the present invention, the vehicle could continue to move due to the forward kinetic energy of the vehicle during the coasting state.Further, the predicting means predicts the duration of the coasting state depending on an operating state of the engine and / or a drag force on the vehicle and / or a profile of a road on which the vehicle travels. Thus, the duration of the coasting state is predicted by the prediction means at the beginning of the coasting state depending on the real-time negative forces acting on the vehicle. The duration of the coasting state predicted by the predicting means results in execution or non-execution of the at least one predetermined test in the coasting state.The comparator compares whether the predicted duration of the coasting state is longer than the duration required to execute the at least one predetermined test in the coasting state. The comparator advantageously comprises a memory for storing a schedule and the duration required to execute each of the at least one predetermined test. Thus, depending on the schedule and duration of the at least one predetermined test, the comparator checks whether the predicted duration is long enough to complete the at least one predetermined test during the vehicle coasting state. The comparator generates a notification signal if the set at least one predetermined test could be performed within the predicted duration of the coasting state. According to another aspect of the present invention, the comparator inhibits initiation of the set at least one predetermined test when it is determined by the comparison that the duration required to execute the at least one predetermined test exceeds the predicted duration of the coasting state. Thus, the comparator reduces unnecessary initiation of the at least one predetermined test in the coasting state.The switching means selectively drives the engine using the starter motor in response to the predicted duration of the coasting state being longer than the duration required to execute the at least one predetermined test in the coasting state. The switching means turns on depending on the schedule of the at least one predetermined test and drives the engine using the starter motor when the at least one predetermined test needs to be carried out. Thus, the engine of the vehicle is operated and the required at least one predetermined test is carried out although the engine is decoupled from the transmission of the vehicle. The engine does not provide negative drag forces to the vehicle even when the at least one predetermined test is performed, and the vehicle may continue to move during the coasting state due to the vehicle's kinetic propulsion energy.The switching means turns off the starter motor in response to completion of the at least one predetermined test in the coasting state. Thus, the engine is shut down at the end of the set at least one predetermined test.According to another aspect of the present invention, a method of controlling operation of an engine in a vehicle during a coasting state of the engine is disclosed. The method includes the steps of determining a start of the coasting state; disabling the engine by disabling supply of fuel to the engine; decoupling the engine from a transmission of the vehicle; predicting a duration of the coasting state; comparing the predicted duration of the coasting state to a duration required to perform at least one predetermined test in the coasting state; driving the engine using a starter motor in dependence on the comparison to perform the at least one predetermined test during engine drive using the starter motor.The method further comprises the step of predicting the duration of the coasting state as a function of an operating state of the engine and / or a towing force on the vehicle and / or a profile of a road on which the vehicle is travelling. Further, a comparison is made as to whether the predicted duration of the coasting state is longer than the duration required to execute the at least one predetermined coasting state test, such that the starter motor is driven in response to the predicted duration of the coasting state being longer than the duration required to execute the at least one predetermined coasting state test. The starter motor is deactivated upon completion of the at least one predetermined test in the coasting mode.Brief Description of the DrawingsAdvantageous embodiments and developments of the invention are evident from the dependent claims. An embodiment of the invention will be explained in principle below with reference to the drawings. In the drawings, there are shown: FIG. 1 is a block diagram illustration of a coasting control device of the present invention; FIG. 2 illustrates a connection between a starter motor, an engine, and the coasting control device according to aspects of the present invention; and FIGS. 3 aand 3 b show a time diagram of the overrun operating state according to the present invention.DESCRIPTION OF THE EMBODIMENTSFIG. 1 shows an example of a block diagram illustration of a coasting control device 100 of the present invention. The coasting control device 100 is connected to an engine 200 of the vehicle. Prediction means 10 of the coasting control device 100 receives the status of the engine 200 from at least one sensor of the engine 200 and determines a start of a coasting state 201 of the engine 200. Prediction means 10 then activates engine control means 250 for decoupling engine 200 from a transmission 300 of the vehicle. The prediction means 10 further predicts a duration (D) of the coasting state 201. A comparator 20 receives the predicted duration (D) of the coasting state 201 from the prediction means 10 and compares the predicted duration (D) with a duration (OTD) required to perform at least one predetermined test in the coasting state 201. The comparator 20 generates a notification signal 21 when the predicted duration (D) is longer than the duration (OTD) required to perform at least one predetermined test 211 in the coasting state 201. Switching means 30 receives the notification signal 21 and selectively drives the engine 200 using the starter motor 50 and performs the at least one predetermined test during the coasting state 201.The coasting control device 100 of the present invention may be an in-vehicle electronic control unit (ECU), for example, an in-vehicle engine management ECU. As shown in FIG. 2, the coasting control device 100 continuously communicates with the engine 200. The vehicle includes the starter motor 50 connected to the engine 200, the engine 200 being coupled to a transmission 300 of the vehicle by the engine control means 250, which could be an automatic clutch 250. The transmission 300 drives at least one wheel 400 of the vehicle. In accordance with aspects of the present invention, when the engine 200 enters the coasting state 201, the engine 200 is decoupled from the transmission 300 by the automatic clutch 250. The coasting control device 100 connected to the engine 200 and the starter motor 50 controls the engine and initiation of the at least one predetermined test to be performed in the coasting state 201 of the engine 200.The prediction means 10 predicts the duration (D) of the coasting state as a function of a plurality of negative forces acting on the vehicle at the beginning of the coasting state 201. The prediction means 10 predicts the duration (D) depending on an operating state of the engine 200 and / or a towing force on the vehicle and / or a profile of a road on which the vehicle travels. The operating state of the engine 200 could include engine speed, vehicle speed, vehicle transmission torque, etc. The drag force on the vehicle could include rolling resistance on the vehicle, aerodynamic negative force on the vehicle, etc. A navigation device could provide the profile of the road on which the vehicle is travelling. The navigation device provides the information about the gradient of the road on which the vehicle is travelling. A road down slope would result in a longer duration (D) of the coasting state 201.The comparator 20 receives the predicted duration (D) of the coasting state 201 from the prediction means 10. the comparator 20 is further connected to a storage unit 25 storing the schedule and the duration (OTD) required for executing the predetermined test 211 in the coasting state. The predetermined test could be correction of long term fuel injection drift into the engine, compensation for cylinder specific torque variation, correction of segment times to determine engine speed from the engine speed sensor, lambda sensor offset correction or NOx sensor offset correction function test, NOx sensor and lambda sensor diagnostics, etc. The comparator 20 compares the predicted duration (D) with the duration (OTD) required to execute the predetermined test 211 in the coasting mode. The comparator 20 compares whether the predicted duration (D) is longer than the duration (OTD) required to perform the at least one predetermined test 211 in the coasting state 201.According to another aspect of the present invention, the comparator 20 disables the predetermined coasting test 211 depending on the predicted duration (D) of the coasting 201. As shown in FIGS. 3 aand 3 b, the coasting control device 100 predicts the coasting duration (D) once the coasting state 201 starts. The comparator 20 of the coasting control device 100 compares the predicted duration (D) of the coasting state 201 with the duration (OTD) required to execute the at least one predetermined test 211 to be executed during the coasting state 201. If it has been determined by the comparison (Fig. 3a) that the duration (OTD) required to perform the at least one predetermined test is short enough to be accounted for in the predicted duration (D) of the coasting state 201, then the comparator allows the test 211 to be performed. On the other hand, if it has been determined (FIG. 3 b) that the test 211 will exceed the predicted duration (D) of the coasting state 201, then the comparator 20 inhibits initiation of the predetermined test 211 during the coasting state.Depending on the predicted duration (D) being longer than the duration (OTD) required to execute the at least one predetermined test 211 in the coasting state 201, and from the schedule of the at least one predetermined test 211, the comparator 20 generates a notification signal 21 for the switching means 30. the switching means 30 turns on the starter motor 50 to drive the engine 200 in response to receiving the notification signal 21. After the engine 200 is driven by the starter motor 50 in the coasting state 201, the demanded at least one predetermined test 211 is executed in the coasting state 201. The engine 200 continues to be decoupled from the transmission 300 during this period of time and thus does not add a negative drag torque to the vehicle's kinetic propulsion energy. Thus, due to the features of the coasting control device 100 of the present invention, the vehicle can travel a further distance in the coasting state 201.In response to the completion of the at least one predetermined test 211 performed in the coasting state 201, the switching means 30 turns off the starter motor 50, thus stopping the operation of the engine 200.It is to be understood that the embodiments set forth in the above detailed description are illustrative only and do not limit the scope of the present invention. The scope of the present invention is limited only by the scope of the independent claims. Many modifications and changes of the above embodiments are contemplated, which are within the scope of the present invention.

Claims

An overrun control device (100) in an automatic transmission (AG) vehicle, the AG vehicle comprising a starter motor (50) coupled to the engine (200) and an engine control means (250) which, in dependence on an overrun operating state (201) of the engine (200), causes decoupling of the engine from a transmission (300) of the AG vehicle, the overrun control device (100) being characterised by - prediction means (10) for determining a start of the overrun operating state (201), activating the engine control means (250) and predicting a duration (D) of the overrun operating state (201); a comparator (20) for comparing the predicted duration (D) of the coasting state (201) with a duration (OTD) required for executing at least one predetermined test (211) in the coasting state (201), and a switching means (30) for selectively driving the engine (200) using the starter motor (50) and performing the at least one predetermined test (211) during the coasting state (201) in dependence on the comparison (21) by the comparator (20).The coasting control device (100) according to claim 1, wherein the prediction means (10) predicts the duration (D) of the coasting state (201) depending on an operating state of the engine (200) and / or a towing force on the vehicle and / or a profile of a road on which the vehicle travels.The coasting control device (100) of claim 1, wherein the comparator (20) compares whether the predicted duration (D) of the coasting state (201) is longer than the duration (OTD) required to execute the at least one predetermined test (211) in the coasting state (201).The coasting control device (100) of claim 1, wherein the comparator (20) inhibits initiation of the at least one predetermined test (211) depending on the predicted duration (D) of the coasting state (201) being shorter than the duration (OTD) required to execute the at least one predetermined test (211) in the coasting state (201).The coasting control device (100) according to claim 3, wherein the switching means (30) selectively drives the engine (200) in response to the predicted duration (D) of the coasting state (201) being longer than the duration (OTD) required to execute the at least one predetermined test (211) in the coasting state (201).The coasting control device (100) according to claim 1, wherein the switching means (30) turns off the starter motor (50) in response to completion of the at least one predetermined test (211) in the coasting state (201).A method for controlling an operation of an engine (200) in an automatic transmission (AG) vehicle during a coasting state (201) of the engine (200), comprising the steps of: - determining a start of the coasting state (201); - disabling the engine (200) by disabling the supply of fuel to the engine (200); - decoupling the engine (200) from a transmission (300) of the AG vehicle; - predicting a duration (D) of the coasting state (201); - comparing the predicted duration (D) of the coasting state (201) with a duration (OTD) required to perform at least one predetermined test (211) in the coasting state (201); driving the engine (200) using a starter motor (50) in dependence on the comparison (21) for executing the at least one predetermined test (211) during driving the engine (200) using the starter motor (50).Method according to claim 7, wherein the duration (D) of the coasting state (201) is predicted depending on an operating state of the engine and / or a towing force on the vehicle and / or a profile of a road on which the vehicle is travelling.Method according to claim 7, wherein it is compared whether the predicted duration (D) of the coasting state (201) is longer than the duration (OTD) required for executing the at least one predetermined test (211) in the coasting state (201).The method of claim 9, wherein the engine (200) is driven by the starter motor (50) in response to the predicted duration (D) of the coasting state (201) being longer than the duration (OTD) required to execute the at least one predetermined test (211) in the coasting state (201).Method according to Claim 7, wherein the starter motor (50) is deactivated in the overrun operating state (201) on termination of the at least one predetermined test (211).

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