DE102006029715B4 - Motor vehicle with a stop-start system and a method for controlling a stop-start system - Google Patents

Abstract

A motor vehicle 5 is provided with an internal combustion engine 10 controlled by a stop-start system and with a drive driven by the engine 10, a first state in which the engine 10 is specifically switched off and started, a second state in which the engine 10 is constantly is operated, and a third state in which the engine is continuously operated and which is used when the motor vehicle is going backwards, operable. The stop-start system is locked in the third state or in the reverse driving state until the speed of the motor vehicle 5 approaches zero and until it is determined that the transmission 11 is not in reverse gear.

Description

This invention relates to a motor vehicle having an internal combustion engine, and more particularly to a motor vehicle having a system for automatically stopping and starting the internal combustion engine without driver intervention. Furthermore, the invention relates to a method for controlling a stop-start system.

It is known to provide a motor vehicle with a stop-start system for automatically stopping and starting an internal combustion engine, which serves to provide motive power to the motor vehicle. A stop-start system automatically shuts off the engine once it is determined that there is an opportunity to improve fuel economy and reduce emissions from the engine.

A problem with such stop-start systems is that they may turn off the engine under certain circumstances since the driver of the motor vehicle does not want to stop the engine or because it is not worthwhile stopping and starting the engine repeatedly in terms of fuel economy , For example, parking a motor vehicle in which forward and backward movement of the motor vehicle is required is impractical and saves little fuel when the engine is turned off during the parking maneuver, only to be restarted almost immediately. Further, in vehicles equipped with power steering using a motor-driven pump, the power steering may not work when the engine is off, whereas in preparation for the next movement, it may be desirable to hit the wheels in steady state. Under such circumstances, it is clearly undesirable to turn off the engine.

Out DE 100 40 094 A1 . DE 34 22 879 A1 and US 2003/0087724 A1 In each case, a motor vehicle with a stop-start system is known in which, when reverse gear is engaged, the automatic shutdown of the internal combustion engine is prevented.

An object of this invention is to provide an improved stop-start system for a motor vehicle and a method for controlling a stop-start system, wherein the stop-start system is to determine exactly whether the engine should be switched off or started.

The object of the invention is achieved by a motor vehicle according to claim 1 and a method according to claim 6. Further developments of the method and the device are the subject of the dependent claims.

According to a first aspect of the invention, there is provided a motor vehicle having an internal combustion engine, a step change transmission and a stop-start system for controlling the running of the engine, the stop-start system comprising at least one shift lever sensor for providing a signal, indicating whether a reverse gear is selected in the transmission, at least one vehicle speed sensor for providing a signal indicating the speed of the motor vehicle, and an electronic control device for receiving the signals from the or each shift lever sensor and the or each vehicle speed sensor, characterized that the electronic control unit is operable to control the stop-start system in a first state in which the engine is selectively stopped and started, and to control in a second and a third state in which the engine is constantly operated, wherein the electronic control unit is operable to from the first state to the second state, when it is determined that the reverse gear is selected to switch to the third state, when it is determined that the reverse gear is selected and that the speed of the motor vehicle is greater than a first predetermined speed limit, and switch from the third state to the second state only when it is determined that the transmission is not in reverse and the speed of the motor vehicle is determined to be below a second predetermined speed limit, and to switch from the second state to the first state only when it is determined that the transmission is not in reverse and the speed of the motor vehicle is greater than a third predetermined speed limit.

The first and second predetermined speed limits may be lower than the third predetermined speed limit.

The first predetermined speed limit may be equal to the second predetermined speed limit.

The first and second predetermined speed limits may be close to zero.

The third predetermined speed limit may indicate a normal movement of the motor vehicle.

According to a second aspect of the invention, there is provided a method of controlling a stop-start system having an electronic control unit used to control the operation of an internal combustion engine that is in one Motor vehicle is mounted with a transmission, provided, the method comprising: operating the stop-start system in a first state in which the engine is selectively turned off and started, operating the stop-start system in a second state in which the engine is continuously operated, and operating the stop-start system in a third state in which the engine is continuously operated, the method comprising: changing from the first state to the second state when a reverse gear is selected, Changing from the second state to the third state when a reverse gear is selected and the speed of the motor vehicle is determined to be above a first predetermined speed limit, switching from the third state to the second state only if it is determined that the transmission is not in reverse and when the speed of the motor vehicle is below a second predetermined speed limit t is determined and switching from the second state to the first state, only if it is determined that the transmission is not in reverse and that the speed of the motor vehicle is above a third predetermined speed limit.

The first and second predetermined speed limits may be less than the third predetermined speed limit.

The first predetermined speed limit may be equal to the second predetermined speed limit.

The first and second predetermined speed limits may be close to zero.

The third predetermined speed limit may indicate that the vehicle is being driven forward at a greater speed than would normally be used for a maneuver.

Now, the invention will be described by way of example with reference to the accompanying drawings. Hereby show:

1 a schematic representation of a motor vehicle with a stop-start system according to the invention; and

2 a diagram showing the different states in which the stop-start system can work.

With reference to 1 becomes a motor vehicle 5 with a motor 10 shown, the one-step gearbox or transmission 11 drives. An engine starter in the form of an integrated starter generator 13 is from the engine 10 driven or drives this. In this case, the starter generator 13 from the engine 10 by a flexible drive in the form of one with a crankshaft of the engine 10 drivingly connected drive belt or a drive chain 14 driven or drives this. The starter generator 13 is with a source of electrical energy in the form of a battery 15 connected and used to start the engine 10 , A driver-operable on-off device in the form of a key-operated ignition switch 17 Used to control the overall operation of the engine 10 , Ie. if the engine 10 is running, the ignition switch is located 17 in an 'on' position, and when the ignition switch 17 is in an 'off' position, the engine can 10 do not walk. The ignition switch 17 also has a third instantaneous position for manually starting the engine 10 serves. It is understood that other devices may be used to provide this functionality, and that the invention is not limited to the use of an ignition switch.

An electronic control unit 16 is with the starter generator 13 with the engine 10 , with a shift lever sensor 12 That is used to monitor whether the gearbox 11 is in neutral or in a forward or reverse gear, and with a vehicle speed sensor 21 connected to measuring the rotational speed of an impeller 20 serves. It will be appreciated that other means of detecting gear engagement could be used, for example, one sensor could be provided to determine if the transmission is in neutral and a second sensor could be used to indicate the selection of reverse gear. such as a reversing light sensor. If no signals are received from the neutral and reverse sensors in such an arrangement or the sensors indicate that these conditions are not present, it can be assumed that a forward gear is selected.

The electronic control unit 16 receives several signals from the motor 10 , including a signal indicating the speed of the motor 10 from a speed sensor (not shown) and sends signals to the engine 10 used to control the shutdown and cranking of the engine 10 serve. In this case, the engine is 10 a spark-ignited engine 10 , and that of the electronic control unit 16 transmitted signals are used to control a (not shown) fuel supply system for the engine 10 and a (not shown) ignition system for the engine 10 , If the engine was a diesel engine, then only the fuel supply of the engine would be controlled.

During normal engine operation is the electronic control unit 16 operable to the engine 10 to control supplied fuel and to adjust the ignition system so that the engine is supplied to the engine at the correct times ignition sparks for generating the desired torque.

The electronic control unit 16 Further controls the operation of the stop-start system, which is operable in three states, a first or stop-start running state, a second state with deactivation of stop-start and a reverse driving state. It is understood, however, that one or more separate electronic control units could be used to control the normal operation of the engine 10 to control, and that the electronic control unit 16 only the stop-start operation of the engine 10 can control.

In the first or stop-start state, the engine becomes 10 from the electronic control unit 16 selectively parked and started without driver intervention when one or more predetermined vehicle operating conditions are present, as is well known in the art.

For the purpose of this example, if the transmission is an automatic transmission 11 is turned off the engine when it is determined that the motor vehicle 5 stands still and a (not shown) brake pedal has been stepped beyond a predetermined period of time. If the transmission is a manual transmission, the engine is turned off when it is determined that the motor vehicle 5 stands still and a clutch pedal is not kicked.

The motor 10 is automatically restarted when an automatic transmission detects that the brake pedal has been released, or when the clutch pedal is depressed in a manual transmission.

It is understood, however, that various alternative predetermined vehicle operating conditions could be used to decide when the engine is running 10 should be started and stopped, and that the invention is not limited to the use of these specific vehicle operating conditions.

When the stop-start system is operating in the second state, the engine becomes 10 constantly operated as long as the ignition switch 17 remains in the 'on' position.

The electronic control unit 16 is further operable to determine whether operating the engine in the first state is appropriate by checking one or more engine operating parameters such as coolant temperature, whether catalysts associated with the engine are starting, and whether the engine is rotating above a predetermined speed. For example, if the coolant temperature is below, for example, 65 ° C, or the catalyst is not started or the speed is greater than, for example, 1,100 rpm (RPM), then entry into the first state is denied and the electronic control unit 16 is operable to place the stop-start system in the second state regardless of the vehicle operating conditions.

Once it is determined that the engine operating conditions are met, the default condition is to place the stop-start system in the first operating state in which it remains, unless input from the shift lever sensor 12 is obtained, indicating that reverse gear is selected.

If the engine 10 already in the second state because of the fact that the engine operating conditions required for operation in the first state are not met, then it remains only in this state until the criteria for leaving this state are met.

To move from the second state or the state with stop start disabled, one of the two criteria must be met. The first criterion is that the gearbox 11 may not be in reverse and that the speed of the motor vehicle 5 must be greater than a third predetermined speed limit, which in this case is 10 km / h. This predetermined speed limit may be any speed that is used to play or indicate that a 'normal movement' of the motor vehicle 5 takes place, is elected. Ie. the vehicle is driven forward at a speed greater than a speed normally used for a maneuver. The gear selection condition of the transmission 11 can through the electronic control unit 16 with the help of the shift lever sensor 12 received signal, and the speed of the motor vehicle 5 is through the electronic control unit 16 from the wheel speed sensor 21 determined.

The second criterion is that the gearbox 11 must be in reverse and the speed of the motor vehicle 5 must be greater than a first predetermined speed limit. In this case, the first predetermined speed limit is 0.5 km / h, but any suitable speed may be near zero to indicate that the vehicle is stationary. The reverse gear selection condition of the transmission 11 is through the electronic control unit 16 from the shift lever sensor 12 received signal, and the speed of the motor vehicle 5 is through the electronic control unit 16 from the wheel speed sensor 21 determined.

When the first criterion is met, the stop-start system changes from the second operating state to the first operating state, and when the second criterion is satisfied, the stop-start system changes from the second operating state to the third operating state reversing the vehicle.

When the stop-start system shifts to the third operating state, the stop-start system remains deactivated, but then a release criteria other than the criterion used to release from the second operating state is used.

The criterion used for release from the third operating state is that of the electronic control unit 16 it must be determined that the transmission 11 is not in reverse, and the speed of the vehicle must be below a second predetermined speed limit, which in this case is 0.5 km / h. It is understood, however, that the second predetermined speed limit may be any suitable speed near zero, indicating that the motor vehicle 5 almost stands still. In this example, the first and second predetermined speed limits are the same, but need not be, and various limits could be used. In all cases, however, the first and second predetermined speed limits are set at a speed substantially less than the third predetermined speed limit and are chosen to be as close to zero as the sensor 21 can reliably detect.

If this criterion is not fulfilled, the stop-start system remains in the third operating state with the stop-start system deactivated. It is understood, however, that when moving the ignition switch 17 in an off position, the system is reset.

Therefore, a stop-start system according to the invention provides a third operating state specifically for the situation, since the motor vehicle 5 moves backwards. This design has the advantage that the stop-start system remains in this operating state until the specific criterion for release from this third operating state is met. Without this third operating state, ie when the stop-start system has only the first and second operating states, the stop-start system would return to the first state when the transmission is not in reverse and the speed of the motor vehicle 5 10 km / h. One problem is that the wheel speed sensor 21 can not determine the direction of travel. Therefore, if the motor vehicle 5 Moving in neutral at over 10 km / h, but in the reverse direction, as may occur when a vehicle is moving in reverse, to exit a driveway, it will change to the first state, even if the vehicle's next movement may be an immediate one Changing the direction of forward calls for, and therefore stopping the engine offers no advantage, or if the driver may want to hit the wheels while the vehicle is stationary and therefore requires a running engine.

It is understood that the invention is applicable to motor vehicles with manual or automatic transmission.

Although the invention has been described above with respect to an embodiment in which the engine is started by means of a starter-generator, it is understood that it is not limited to use with a starter-generator and that it equally applies to a motor vehicle with an alternator or a DC generator could be used to generate electrical energy and with a separate starter to restart the engine.

Now, the method for operating the stop-start system with reference to 2 in which specific steps are described in a predetermined order, described in more detail. It should be understood, however, that the order of these steps may be varied from the order shown without departing from the scope of the invention.

The procedure begins at step 50 what is an "off" or "key off" condition of the ignition switch 17 equivalent. Then the process moves to step 100 when the ignition switch is moved to an 'on' position. After the momentary movement of the ignition switch to a starting position, the method then moves to step 102 in front. Then the process moves to step 110 before, where it is determined whether the conditions for the stop-start operation are met. Ie. whether the engine is warm enough and operating at the predetermined speed. If the conditions are not met, the procedure moves to step 105 in front of where the engine is constantly running while it keeps warming up, and then gets back to crotch 110 changed until some time after starting the condition at step 110 is satisfied and the procedure to step 120 advances.

In the first operating state, the engine 10 from the electronic control unit 16 targeted turned off and started, when certain predetermined vehicle operating conditions are met, the fuel consumption and emissions of the engine 10 to minimize.

The stop-start system stops at step 120 in the first operating state, until at step 130 it is determined that the reverse gear is selected. This can be done by setting a flag to 1 once from the shift lever sensor 12 is detected that the shift lever is in reverse, and then by comparing the state of the flag with a test value. Ie. the state of the flag could be compared with a test value of zero, and if the value is greater than zero, it can be assumed that the reverse gear of the transmission 11 is selected, and the test is passed, otherwise the test is failed. The determination of whether the reverse gear is selected, however, could be made by any other suitable means and is not limited to the setting of such a flag.

If the test has been passed, the electronic control unit changes or switches 16 then to the second operating state, which is through the step 140 is displayed, otherwise it remains at step 120 in the first operating state.

At step 140 becomes the engine 10 constantly operated while the ignition switch 17 one stays. There are two possible criteria for release from step 140 , The first of these is from the electronic control unit 16 used to change from the second operating state back to the first operating state, as by step 180 will be shown.

At step 180 is the electronic control unit 16 operable to determine if the gearbox 11 in reverse, which could be as described above or could be detected by any other suitable means, and also compares the signal from the wheel speed sensor 21 with the third predetermined speed limit, which in this case is 10 km / h, and whether the vehicle speed is above 10 km / h.

It will be understood that the signal from the wheel speed sensor need not be an actual value of the vehicle speed, but may be, for example, a series of pulses received in one second. In this case, using a suitable calibration, the number of pulses per second corresponding to 10 km / h would be used for the test.

For example, if the measured number of pulses per second, S ', corresponding to 10 km / h, is 100, then the test would be:
If 'S'> 100, if 'Yes', then the test is passed and the vehicle speed is greater than 10 km / h, and if 'No', then the test is failed and the speed of the motor vehicle 5 is less than 10 km / h.

If at step 180 These two tests are passed, ie when the gearbox 11 is not in reverse and the vehicle speed is greater than 10 km / h, the method returns to step 120 back and the electronic control unit 16 changes or switches to the first operating state, but if one of these tests is not passed, the method remains at step 140 ,

The other criterion for leaving the second state, by step 150 is shown is that the transmission 11 having a selected reverse gear and the speed of the motor vehicle 5 is greater than a first predetermined speed limit, which in this case is 0.5 km / h.

Determining if in step 150 a reverse gear is selected may be as described above or could be by any other suitable means.

Similarly, the vehicle speed can be determined as above, but in this case using a test value indicating 0.5 km / h. Ie. the test would be as follows using the same calibration:
If 'S'> 5, if 'Yes', then the test is passed, and if 'No', then the test is failed.

If the test fails, the procedure remains at step 140 However, if the test is passed and it is determined that the transmission is in reverse, then the process moves to step 160 in front of where it stays until that step 170 shown release criterion is met. It is understood, however, that when moving the ignition switch 17 to an off position the stop-start system is reset and to step 100 returns when the ignition switch is turned on.

The criterion for leaving the third operating state, that of step 170 is shown is that the transmission 11 can not be in reverse and the speed of the motor vehicle 5 must be below a second predetermined speed limit, which in this case is 0.5 km / h.

The determination at step 170 whether the reverse gear is selected can be as described above or could be done by any other suitable means.

Similarly, the determination of the vehicle speed can be made as above, but in this case using a test value indicating 0.5 km / h. Ie. the test would be as follows using the same calibration:
If 'S'<5, if 'yes', then the test is passed, and if 'No', then the test is failed.

If the test fails, the procedure remains at step 160 However, if the test is passed and it is determined that the transmission is not in reverse, then the procedure returns to step 140 back to where it stays until one of the release criteria of step 140 is satisfied.

It is understood that the steps 105 . 120 . 140 and 160 Operating states of the stop-start system are the steps 50 and 100 Operating conditions of the ignition switch 17 are and that the steps 110 . 130 . 150 . 170 and 180 Tests are used to determine the correct operating condition.

Although the measurement of the vehicle speed is above with respect to an impeller sensor 21 As such sensors are often already present as part of a brake anti-lock brake system on the motor vehicle, it is understood that other suitable means for determining the speed of the vehicle may be used, such as the rotational speed of an output shaft of the transmission 11 measuring sensor.

Claims (10)

A motor vehicle having an internal combustion engine, a step change transmission, and a stop-start system for controlling the running of the engine, the stop-start system comprising at least one shift lever sensor for providing a signal indicating whether the transmission is reverse, at least one vehicle speed sensor for providing a signal indicative of the speed of the motor vehicle, and an electronic control device for receiving the signals from the or each shift lever sensor and the or each vehicle speed sensor, the electronic control device being operable to operate the stop-start system in one controlling the first state in which the engine is selectively stopped and started, and in a second and third states in which the engine is continuously operated, the electronic control device being operable to change from the first state to the second state, when it is determined that the reverse gear is selected to change from the second to the third state when it is determined that the reverse gear is selected and that the speed of the motor vehicle is greater than a first predetermined speed limit, and to change from the third state to the second state, only when it is determined that the transmission is not in reverse and that the speed of the motor vehicle is below a second predetermined speed limit and to change from the second state to the first state only if it is determined that the transmission is not in reverse and that the Speed of the motor vehicle is above a third predetermined speed limit. A motor vehicle according to claim 1, characterized in that the first and second predetermined speed limit values are smaller than the third predetermined speed limit value. Motor vehicle according to claim 1 or 2, characterized in that the first predetermined speed limit value is equal to the second predetermined speed limit value. Motor vehicle according to one of claims 1 to 3, characterized in that the first and the second predetermined speed limit value are close to zero. Motor vehicle according to one of claims 1 to 4, characterized in that the third predetermined speed limit indicates that the vehicle is driven forward at a greater speed than would normally be used in a maneuver. A method of controlling a stop-start system with an electronic control unit used to control the operation of an internal combustion engine installed in a motor vehicle having a transmission, the method comprising: operating the stop-start system in a first state in which the engine is selectively stopped and started, operating the stop-start system in a second state in which the engine is constantly operated, and operating the stop-start system in a third state in which the engine is constantly operated switching, wherein the method comprises: changing from the first state to the second state when a reverse gear is selected, changing from the second state to the third state when a reverse gear is selected and the speed of the motor vehicle is determined to be above a first predetermined speed limit from the third state to the second state only when it is determined that the Transmission is not in reverse, and when the speed of the motor vehicle is determined to be below a second predetermined speed limit, and switching from the second state to the first state, only if it is determined that the transmission is not in reverse and the speed of the motor vehicle is above a third predetermined speed limit. A method as claimed in claim 6, characterized in that the first and second predetermined speed limit values are less than the third predetermined speed limit value. A method according to claim 6 or 7, characterized in that the first predetermined speed limit value is equal to the second predetermined speed limit value. A method as claimed in claim 7 or 8, characterized in that the first and second predetermined speed limits are close to zero. Method according to one of claims 7 to 9, characterized in that the third predetermined speed limit indicates that the vehicle is driven forward at a greater speed than would normally be used in a maneuver.

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