CN111497815A

CN111497815A - Method for preventing engine from stopping

Info

Publication number: CN111497815A
Application number: CN202010068731.5A
Authority: CN
Inventors: 加里·大卫·佩斯利; 大卫·赫斯基; 帝力·拉杰·布德; 克里斯·爱德华·派德勒
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2019-01-30
Filing date: 2020-01-21
Publication date: 2020-08-07
Also published as: GB201901246D0; GB2580924B; GB2580924A; DE102020100650A1

Abstract

A method is disclosed wherein the engine 10 of the motor vehicle 5 is prevented from stopping if the non-depressed accelerator pedal 18 is depressed during a test period. The first test period is used when the multi-speed transmission 11 is in neutral, and the longer second test period is used when the multi-speed transmission 11 is not in neutral.

Description

Method for preventing engine from stopping

Technical Field

The present invention relates to a motor vehicle having an internal combustion engine, and in particular to a motor vehicle having a system for automatically stopping and starting an internal combustion engine.

Background

It is known to provide a motor vehicle having a transmission with a Stop-Start system for an automatic Stop (Auto-Stop) and automatic Start (Auto-Start) internal combustion engine for powering the motor vehicle.

Current automatic start-stop system settingsDesigned to reduce fuel consumption and CO by automatically shutting down the engine when certain conditions are met₂However, systems are being developed that extend the automatic start-Stop behavior, including stopping the engine while the transmission is still in Gear, so-called Stop-in-Gear (SIG) systems, and which may be designed to allow the engine to Stop automatically while the vehicle is still traveling at low speeds.

A problem with current start-stop systems is that although early stopping of the engine is advantageous for fuel savings, if the engine stops prematurely such that it must be restarted during or shortly after the engine is stopped, this may cause driver dissatisfaction and increased part wear due to additional stopping events.

Therefore, careful consideration of parameters for preventing the automatic stop of the engine is required in order to maximize fuel economy while preventing the accidental stop of the engine.

Disclosure of Invention

It is an object of the present invention to provide a method and apparatus for preventing engine stops mounted on a motor vehicle having a manual multi-speed transmission that is easy to implement and overcomes the problem of undesirable engine stops.

According to a first aspect of the present invention, there is provided a method of preventing an engine stop of a motor vehicle having a gear stop-start system, an accelerator pedal, a manual multi-speed transmission and a driver operated clutch pedal selectively disengaging a clutch interposed between the engine and the multi-speed transmission, wherein the method comprises checking whether the accelerator pedal is depressed, if the accelerator pedal is not depressed, setting a first test period when the multi-speed transmission is in neutral and a second test period when the multi-speed transmission is not in neutral, and checking whether the accelerator pedal is depressed within the first test period when the multi-speed transmission is in neutral and checking whether the accelerator pedal is depressed within the second test period when the multi-speed accelerator is not in neutral and if the accelerator pedal is depressed within the corresponding period, the engine is prevented from being automatically stopped.

The second test period may be greater than the first test period.

The first test time period may be set to a predetermined value and the second test time period may be set to a predetermined value.

The second test period may be an adaptive value based on a value indicative of a previous accelerator pedal usage.

In the event that the value indicative of the previous accelerator pedal usage indicates a small deviation from the accelerator pedal non-contact position that has been used by the user of the motor vehicle, the value of the second test period of time may be set to a value that is shorter than the period of time that would be set if the value indicative of the previous accelerator pedal usage indicated that the accelerator pedal was significantly moved by the user from the non-contact position.

Alternatively, the second test period may vary based on the average speed of the vehicle.

According to a second aspect of the present invention there is provided a motor vehicle capable of gear stop and start operations, the motor vehicle having an internal combustion engine, a manual multi-speed transmission driveably connected to the engine by a clutch, an accelerator pedal providing user input from a desired output of the engine, a gear lever movable between at least one position in which a gear of the multi-speed transmission is selected and a neutral position in which the gear of the multi-speed transmission is not selected, and an electronic controller connected to a plurality of sensors including a transmission sensor providing a signal indicating whether the multi-speed transmission is in neutral and an accelerator pedal position sensor providing an output indicating whether the accelerator pedal is depressed, wherein the electronic controller is operable to check whether the accelerator pedal is depressed, and if the accelerator pedal is not depressed, the electronic controller is operable to check whether the accelerator pedal is depressed during a first test period when the multi-stage transmission is in neutral, to check whether the accelerator pedal is depressed during a second test period when the multi-stage transmission is not in neutral, and to prevent automatic stopping of the engine if the accelerator pedal is depressed within the corresponding test period.

The second test period may be greater than the first test period.

The electronic controller is operable to adapt the second test period based on a value indicative of a previous accelerator pedal usage.

In the event that the value indicative of previous accelerator pedal usage indicates a small deviation from the accelerator pedal non-contact position that has been used by the user of the motor vehicle, the electronic controller is operable to set the value of the second test period to a shorter period than the period set in the event that the value indicative of previous accelerator pedal usage indicates that the accelerator pedal has been significantly moved by the user from the non-contact position.

Alternatively, the electronic controller is operable to vary the second test period based on the average speed of the vehicle.

According to a third aspect of the present invention there is provided a method of automatically starting and stopping an engine of a motor vehicle capable of an in-gear stop operation, wherein the method uses a method of preventing engine stop according to said first aspect of the present invention to prevent engine stop.

Drawings

The invention will now be described by way of example with reference to the accompanying drawings:

FIG. 1 is a schematic illustration of a motor vehicle having an internal combustion engine and a stop-start system;

FIG. 2 is a high level flow chart illustrating a method for controlling the automatic starting and stopping of the internal combustion engine shown in FIG. 1; and

FIG. 3 is a flowchart illustrating various steps in forming a method of inhibiting stopping of the internal combustion engine shown in FIG. 1 in accordance with the present invention.

Detailed Description

Referring to FIG. 1, a motor vehicle 5 is shown having an engine 10 driving a manually controlled, multi-speed transmission 11. The transmission 11 is drivably connected to the engine 10 through a clutch (not shown) that is engaged or released by the driver of the motor vehicle 5 and has a gear lever 9 that operates a gear selection mechanism (not shown). It should be understood that the clutch pedal 25 may directly influence the clutch engagement state through a mechanical or hydraulic connection, or the clutch engagement state may be controlled using a by-wire arrangement (e-clutch).

The shift lever 9 is movable between a plurality of positions including at least one position where a gear forming part of the multi-speed transmission 11 is selected and a neutral position where a gear of the multi-speed transmission 11 is not selected. When the shift lever 9 is moved to the neutral position, the multi-stage transmission 11 is said to be in a "neutral" state in which the driving force cannot be transmitted by the multi-stage transmission 11, and when the shift lever 9 is moved to the shift position, the multi-stage transmission 11 is said to be in a "shift state" in which the driving force can be transmitted by the multi-stage transmission 11.

An engine starter is drivably connected to the engine 10, and in this case is a starter-generator 13, the starter-generator 13 being connected to the crankshaft of the engine 10 by a flexible drive in the form of a belt or chain drive 14. The starter-generator 13 is connected to a source of electrical energy in the form of a battery 15 and is used to start the engine 10 and to recharge the battery 15 when the starter-generator 13 is operating as a generator. The present invention is not limited to the use of the starter-generator 13, and the starter-generator 13 may be replaced with a starter motor for starting the engine 10.

It should be appreciated that during starting of the engine 10, the starter-generator 13 drives a crankshaft of the engine 10, and at other times the starter-generator 13 is driven by the engine 10 to produce electrical power.

The overall operation of the engine 10 is controlled using a driver-operable on-off device in the form of a key-operable ignition switch 17. That is, when the engine 10 is running, the ignition switch 17 is in the "key-on" position, and when the ignition switch 17 is in the "key-off" position, the engine 10 cannot run. Ignition switch 17 also includes a third momentary position for manually starting engine 10. It will be appreciated that other means may be used to provide this function and the invention is not limited to use with a key operable ignition switch.

The electronic controller 16 is connected to the starter-generator 13, the engine 10, a transmission sensor 12 for monitoring whether the transmission 11 is in neutral, and a wheel speed sensor 21 for measuring the rotational speed of the wheels 20, a brake pedal position sensor 24 for monitoring the position of a brake pedal 23, a clutch pedal position sensor 26 for monitoring the position of a clutch pedal 25, and an accelerator pedal position sensor 19 for monitoring the position of an accelerator pedal 18.

An accelerator pedal 18 provides a driver input of a desired output of engine 10. The accelerator pedal 18 is said to be "depressed" or in a "depressed state" if it has moved from a rest position, in which it has not been contacted by the operator of the vehicle 5 (referred to as "not depressed" or "not contacted"), to a position in which it has moved from the non-contacted state.

It should be understood that the term transmission sensor is not limited to a sensor that monitors the position of the gear lever 9 or the connected gear selection mechanism, but can be any device that provides feedback whether the transmission 11 is in neutral.

Similarly, the term brake pedal sensor is not limited to a sensor that monitors the position of the brake pedal 23, but may be any device that provides feedback whether the operator of the motor vehicle 5 has applied pressure to the brake pedal 23 to apply the brakes of the motor vehicle 5. For example, a brake pedal sensor may monitor fluid pressure in one or more brake lines. When the brake pedal 23 has been depressed sufficiently to apply the brakes, it is said to be in a "depressed state" or "depressed position".

In this case, the clutch pedal position sensor 26 includes first and second switches (not shown) arranged to give an indication of the state of the clutch pedal 25 by opening or closing the switches when the clutch pedal 25 reaches a certain position.

If the user of the vehicle 5 does not contact the clutch pedal 25, it is said to be in a "released state" and the associated clutch will be fully engaged.

When the clutch pedal 25 is moved to a fully depressed position, it is said to be in a "depressed state" and the associated clutch will be fully disengaged.

When the clutch pedal 25 has been moved to a position where the clutch will be partially disengaged or partially engaged, it is said to be in a "depressed state".

The two switch positions define a lower limit and an upper limit of the depressed state, and in one example, the two switch positions are set to a clutch stroke percentage of the untouched position of 10% for the first switch and 75% for the second switch.

The clutch must be engaged when a signal is sent from the first switch to the electronic controller 16 (clutch pedal released state), and the clutch must be disengaged when a signal is sent from the second switch to the electronic controller 16 (clutch pedal depressed state).

As an alternative to this arrangement, a single sensor, such as a rotary potentiometer, may be used to monitor the actual position of the clutch pedal 25, and the determination of when the clutch is engaged or disengaged may then be performed by the electronic controller 16 using signals received from the position sensor. In this case, the high-side and low-side clutch signals representing the position of the clutch pedal 25 will be determined by the electronic controller 16 based on the signals received from the clutch pedal position sensor, where it is known that the clutch will be engaged or disengaged.

Electronic controller 16 receives a plurality of signals from engine 10 including a signal from a speed sensor (not shown) indicative of a rotational speed of engine 10 and sends signals to engine 10 for controlling shutdown and startup of engine 10. In this case, the engine 10 is a spark-ignition engine 10, and signals sent from the electronic controller 16 are used to control a fuel supply system (not shown) of the engine 10 and an ignition system (not shown) of the engine 10. If the engine 10 is to be a diesel engine, only the fueling of the engine will be controlled. Electronic controller 16 contains various components including a central processing unit, memory devices, one or more timers, and signal processing devices for converting signals from sensors connected to electronic controller 16 into data that electronic controller 16 uses to control operations, particularly the automatic stopping and starting of engine 10.

During normal engine operation, electronic controller 16 is operable to control the fuel supplied to engine 10 and to adjust the ignition system to supply spark to engine 10 from the spark plug at the correct timing to produce the desired engine torque.

Electronic controller 16 controls operation of engine 10 to operate in two modes: a first or stop-start mode of operation and a second or continuous mode of operation. However, it will be appreciated that one or more separate electronic controllers may be used to control normal operation of engine 10, and that electronic controller 16 may merely control switching of engine 10 between two operating modes and automatically stopping and starting engine 10.

When the engine 10 is operating in the second mode, it continues to operate as long as the ignition switch 17 remains in the "on" position. The second mode is used when certain predetermined conditions required for operation in the first mode are not present.

One condition for determining whether the engine 10 is operating in the second mode or the first mode is whether the motor vehicle 5 is moving at a speed above a predetermined speed. The engine 10 is operated in the second mode if the motor vehicle 5 is moving above a predetermined speed.

If the motor vehicle 5 is moving at a speed below a predetermined speed, the engine 10 may be operated in a first mode in which automatic stop-start operation of the engine will occur if other conditions required for the operation are present.

These conditions may include engine coolant temperature, whether any catalytic converters associated with the engine are shut down, and whether the engine is rotating within a predetermined speed range.

When it is determined that all of the required operating conditions for start-stop operation have been met, then the default condition of the electronic controller 16 is to place the stop-start system in the first operating mode.

In a first or stop-start mode, engine 10 is selectively stopped and started by electronic controller 16 when one or more predetermined engine stop and start conditions exist. These stop and start conditions are based on signals received by the electronic controller 16 from the throttle sensor 19, the brake sensor 24, the clutch sensor 26, and the gear selection sensor 12. The positions or states of the clutch pedal 25, the accelerator pedal 18, the brake pedal 23, and the transmission 11 are various motor vehicle variables used to control the operation of the engine 10.

Although the measurement of the speed of the motor vehicle has been described above with reference to the use of wheel sensors 21, as such sensors are typically already present on motor vehicles as part of a brake anti-lock system, it will be appreciated that other suitable means may be used to determine the speed of the motor vehicle 5, for example a sensor for measuring the rotational speed of the output shaft from the transmission 11.

A method for controlling the automatic start and stop of the internal combustion engine 10 in the first operation mode will now be described with reference to fig. 2.

It should be appreciated that electronic controller 16 is programmed to control engine 10 according to this method.

Referring to fig. 2, the method begins at block 110 with the ignition switch 17 in the "key-off" position, then proceeds to block 115 when the ignition switch 17 is moved to the "key-on" position, and then follows the momentary movement of the ignition switch 17 to the starting position shown at block 120, and then proceeds to block 125, where the engine 10 is running.

From box 125, the method proceeds to box 130, where engine operating parameters required to stop engine 10 are checked at box 130. In accordance with the present invention, one of these parameters is not to prevent an automatic stop of the engine 10, as described below with reference to fig. 3.

If the autostop is prevented or other desired parameters have not been met, the engine 10 will not be stopped and the method returns to block 125 where the engine 10 is still running and will continue to cycle around blocks 125 and 130 until the desired conditions in block 130 have been met and the autostop is not prevented.

However, if stopping is not prevented and the required conditions for automatic stopping are met, the method proceeds to block 140 where the engine 10 is stopped or switched to a stopped state at block 140. In this case, the engine 10 is stopped by cutting off the fuel supply and cutting off the ignition supply to the engine 10 so that the spark plug of the engine 10 does not generate a spark.

From frame 140, the method proceeds to frame 150, at which frame 150 the engine 10 is in a stopped state in which the engine 10 will remain until one or more of the particular predetermined engine start conditions specified in frame 160 have been met.

Various engine start conditions may be used and will vary depending on whether the transmission 11 is in neutral or not. For example, if the transmission 11 is not in neutral, one of the conditions is that the clutch pedal 25 is depressed, whereas if the transmission is in neutral, this is not necessarily so.

If the predetermined engine start condition has been met, the method proceeds from block 160 to block 170, in which case the engine 10 is automatically started or switched to a restart state by energizing the starter-generator 13.

The method then proceeds from block 170 to block 180, at which block 180 the engine 10 is again operated, and then returns to block 125 with the engine operating. And will continue to cycle through blocks 125 through 180 as previously described as long as the "key-on" state continues to be maintained.

If the conditions for engine start have not been met at block 160, the method returns to block 160, and then the method returns to block 150, where the engine 10 is stopped and will continue to loop through

blocks

150 and 160 until the predetermined engine start conditions have been met.

It will be appreciated that if at any time there is a key-off event, the method will end and will actually return to block 110.

Referring to FIG. 3, a method of preventing engine stop in a motor vehicle capable of both gear stop and start operation is shown.

The method 200 begins at block 205, where block 205 forms a portion of the method step 130 shown in FIG. 2. In block 205, it is checked whether the accelerator pedal 18 is depressed. This is done by checking the output of the accelerator pedal sensor 19.

If the accelerator pedal 18 is depressed, engine 10 is prevented from stopping, whether or not other conditions exist that are appropriate for stopping engine 10, and method 200 will proceed to block 210 and then return to block 205. That is, if the accelerator pedal 18 is depressed by the user of the motor vehicle 5, the engine 10 is never allowed to automatically stop.

However, if the accelerator pedal 18 is not depressed, the method 200 will proceed from block 205 to block 220.

It should be understood that the output of the accelerator pedal sensor 19 is a calibration signal, and the output from the accelerator pedal sensor 19 is not necessarily zero when the operator of the motor vehicle 5 is not in contact with the accelerator pedal 18. Thus, the output of the accelerator pedal sensor 19 indicating that the user is not touching the accelerator pedal 18 is used in the test set forth in block 205.

In block 220, it is checked whether the transmission 11 is in neutral. This may be done in any suitable manner, for example by monitoring the output from a neutral sensor.

If it is determined that the transmission 11 is in neutral, the method 200 will proceed from block 220 to block 230, where a first test time period is set at block 230 (T1).

However, when the check of block 220 determines that the transmission 11 is not in neutral, the method 200 will proceed from block 220 to block 240, where a second test time period is set at block 240 (T2).

The first test period (T1) is less than the second test period (T2), that is, T1 < T2.

In one example, T1 is set to 0.5 seconds and T2 is set to 2.0 seconds.

The use of two different test periods is a key feature of the invention depending on whether the transmission 11 is in neutral or not, since if the transmission 11 is in neutral, a very short period of time is allowed to be used, but if the transmission 11 is not in neutral, a more conservative longer period of time is used.

If this is not the case, a longer second test period T2 must be used to ensure that the engine does not stop prematurely, so that it must be restarted during engine shutdown, which may cause driver dissatisfaction and increased part wear due to additional stopping events, and more reliable operation of the motor vehicle 5. Although in practice the difference between the two time periods T1 and T2 does not seem to be significant, an engine that can be stopped 1.5 seconds earlier is beneficial both in terms of user perception and long term fuel economy.

In either case, the method 200 proceeds from

blocks

230 and 240 to block 250, where the timing is started in block 250. The timer is initialized with the test time periods T1 and T2 set in

blocks

230 and 240, respectively, and started to count down from the initial value T1 or T2. It should be appreciated that two separate timers may alternatively be used, one for the first test period T1 and the other for the second test period T2.

While the timer at block 250 is counting down, the position of the accelerator pedal 18 is continuously checked as shown in block 260, and if the timer is still counting down, the user depresses the accelerator pedal 18 to move it from a non-contacted position, then the method 200 will return to block 210 and will prevent automatic stopping of the engine 10, otherwise it will proceed to block 270 and then return to block 250, provided the time set for the timer has not expired.

If the accelerator pedal 18 has not been depressed before the end of the test period (T1 or T2), the method 200 will proceed to block 280 to check if there are other parameters necessary to produce an automatic stop of the engine 10, as shown in block 270.

If these parameters are satisfied, the method 200 will return to block 140 of the primary method shown in FIG. 2, and if the parameters have not been satisfied, the method 200 will return to block 125 of the primary method shown in FIG. 2.

In all cases, one of the parameters required for the automatic engine stop is that the vehicle 5 does not run above a predetermined road speed. Determining whether the motor vehicle 5 is traveling involves comparing the current measured vehicle speed obtained from the road speed sensor 21 with a predetermined road speed of, for example, 20 Kph.

Other parameters required to allow the engine to be automatically stopped depend on the configuration of the motor vehicle 5 and the electronic controller 16, but for example, in the case of a stop in the geared state, the clutch pedal 25 is required to be in a fully depressed position (clutch off), the brake pedal 23 is required to be in a depressed state, and in the case of a stop in the neutral state, it is only necessary to put the transmission in neutral and the vehicle speed is below a predetermined road speed.

Although the test period is a fixed value as described previously, this need not be the case, and an adaptive value of the test period may be used based on the most recent accelerator pedal usage.

For example, if the user of the motor vehicle 5 is recently driving with a significant demand from the driver indicated by the accelerator pedal having been significantly depressed, it is unlikely that the engine will be stopped soon or properly and may be used for a longer period of time during the test period.

However, if the most recent accelerator pedal usage indicates that the user of the motor vehicle 5 has used a very small deviation from the accelerator pedal non-contact position at low vehicle speeds within a previous predetermined period of time, e.g., 30 to 90 seconds, the engine stop is more likely to be closer to the driver's expectation, and a shorter test time may be used.

When the transmission 11 is in gear, the "most recent average engine load" or "pedal position" calculated by the rolling average filter over the previous predetermined period of time may be used as a value indicative of the previous accelerator pedal usage for the second test period (T2).

An alternative approach is to have the T2 timer vary based on the average speed of the vehicle. If the average speed is low (e.g. city driving) the timer may be shortened, whereas if the average speed is high (e.g. highway driving) the user may intend to accelerate as quickly as possible. That is, the second test period T2 is changed based on the average speed of the vehicle. Therefore, the second period of time varies inversely with respect to the average speed of the vehicle.

In most cases, the first test period (T1) will always be set to near zero, so there is typically no need to adaptively manage this test period.

It will be understood by those skilled in the art that while the present invention has been described by way of example with reference to one or more embodiments, the invention is not limited to the disclosed embodiments and alternative embodiments may be constructed without departing from the scope of the invention, which is defined by the appended claims.

Claims

1. A method of preventing an engine stop of a motor vehicle having a gear stop-start system, an accelerator pedal, a manual multi-speed transmission and a driver operated clutch pedal selectively disengaging a clutch between the engine and the multi-speed transmission, wherein the method comprises checking if the accelerator pedal is depressed and, if the accelerator pedal is not depressed, setting a first test period when the multi-speed transmission is in neutral and setting a second test period when the multi-speed transmission is not in neutral, and the method further comprises checking if the accelerator pedal is depressed during the first test period when the multi-speed transmission is in neutral and checking if the accelerator pedal is depressed during the second test period when the multi-speed transmission is not in neutral, and preventing an automatic stop of the engine if the accelerator pedal is depressed within a corresponding time period.

2. The method of claim 1, wherein the second test time period is greater than the first test time period.

3. A method according to claim 1 or claim 2, wherein the first test time period is set to a predetermined value and the second test time period is set to a predetermined value.

4. The method of claim 1 or claim 2, wherein the second test time period is an adaptive value based on a value indicative of a previous accelerator pedal usage.

5. The method of claim 4, wherein in the event that the value indicative of a previous accelerator pedal usage indicates a small deviation from an accelerator pedal non-contact position that has been used by a user of the motor vehicle, the value of the second test time period may be set to a shorter time period than a time period set in the event that the value indicative of a previous accelerator pedal usage indicates that the accelerator pedal was significantly moved by the user from the non-contact position.

6. The method of claim 4, wherein the second test time period varies based on an average vehicle speed.

7. A motor vehicle capable of shift stop and start operations, the motor vehicle having an internal combustion engine, a manual multi-speed transmission driveably connected to the engine by a clutch, an accelerator pedal for providing user input of a desired output of the engine, a gear lever movable between at least one position in which a gear of the multi-speed transmission is selected and a neutral position in which the gear of the multi-speed transmission is not selected, and an electronic controller connected to a plurality of sensors including a transmission sensor providing a signal indicating whether the multi-speed transmission is in neutral or not and an accelerator pedal position sensor providing an output indicating whether the accelerator pedal is depressed or not, wherein the electronic controller is operable to check whether the accelerator pedal is depressed or not, and if the accelerator pedal is not depressed, the electronic controller is operable to check whether the accelerator pedal is depressed during a first test period when the multi-stage transmission is in neutral, to check whether the accelerator pedal is depressed during a second test period when the multi-stage transmission is not in neutral, and to prevent automatic stopping of the engine if the accelerator pedal is depressed within the corresponding test period.

8. The vehicle of claim 7, wherein the second test period is greater than the first test period.

9. A vehicle according to claim 7 or claim 8, wherein the first test period is set to a predetermined value and the second test period is set to a predetermined value.

10. A vehicle as claimed in claim 7 or claim 8 wherein the electronic controller is operable to adapt the second test period based on a value indicative of previous usage of the accelerator pedal.

11. The vehicle of claim 10, wherein in the event that the value indicative of previous accelerator pedal usage indicates a small deviation from an accelerator pedal non-contact position that has been used by a user of the motor vehicle, the electronic controller is operable to set the value of the second test time period to a shorter time period than a time period set in the event that the value indicative of previous accelerator pedal usage indicates that the accelerator pedal was significantly moved by the user from the non-contact position.

12. The vehicle of claim 10, wherein the electronic controller is operable to vary the second test period based on an average vehicle speed.

13. A method of automatically starting and stopping an engine of a motor vehicle capable of gear stop operation, wherein the method prevents the engine from stopping using the method of preventing engine stop according to claim 1.