JP2009074400A - Control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an engine capable of executing fuel cut control at appropriate timing while preventing control hunting during cruise control. <P>SOLUTION: An E/G_ECU 15 shifts control to fuel cut control via delay control using relatively longer delay time than non-cruise control time upon determining that the engine has assumed an idle state during cruise control. Consequently, control hunting due to repetition of fuel cut control and fuel recovery at short cycles can be exactly prevented. In this case, the E/G_ECU 15 cancels the delay control and shifts control to the fuel cut control upon recognizing the necessity of deceleration based on a predetermined operation state of one's own vehicle 1 during cruise control. Consequently, fuel cut control can be performed at appropriate timing. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine control device that performs fuel cut control during deceleration when the throttle valve is fully closed and the engine speed is in an idle state equal to or higher than a predetermined speed.

  In recent years, on-board radar means such as millimeter wave radar and infrared laser radar, imaging means such as stereo cameras and monocular cameras, or combination of these radar means and imaging means recognizes information outside the vehicle and recognizes outside the vehicle. Various proposals have been made for driving support devices that perform various types of vehicle control based on information. As one of the functions of such a driving support device, a cruise control with an inter-vehicle distance control (ACC;) that selectively performs a follow-up running control and a constant speed running control according to the capture state of a preceding vehicle ahead of the host vehicle. Adaptive Cruise Control) function is widely used.

  Further, in engine control, for example, when it is determined that the throttle valve is fully closed and the engine speed is in an idle state equal to or higher than a predetermined speed, fuel cut control (fuel cut during deceleration) is performed to stop fuel injection into the engine. Control) is known.

Furthermore, as a technique for preventing control hunting due to fuel cut during deceleration in a vehicle having a cruise control function, for example, Patent Document 1 discloses a constant speed travel control when a request for deceleration fuel cut control occurs. (Cruise control) is determined, and if constant speed running control is being performed, a technique for setting a fuel cut delay time or the like longer than that during non-constant speed running control is disclosed. Yes.
JP 2004-211601 A

  However, if the fuel cut delay time during execution of cruise control is set to be long as in the technique disclosed in Patent Document 1 described above, for example, when the vehicle is traveling on a steep downhill, a predetermined operation is performed. In the state, the intervention of the deceleration control by the fuel cut control is delayed, and there is a possibility that the occupant feels uncomfortable because the vehicle speed overshoots.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine control device that can perform fuel cut control at an appropriate timing while preventing control hunting during cruise control.

  The present invention is mounted on a vehicle having a cruise control function, and includes idle determination means for determining whether or not the engine is in an idle state during traveling, and fuel cut control for the engine when the engine is in an idle state. A fuel cut means to perform, a delay control means to perform a delay control from when the engine is in an idle state to when the fuel cut control is started, and a delay time related to the delay control at the cruise control when the non-cruise control is performed. An engine control device having a delay time setting means for setting the delay time longer than the delay time, and the vehicle needs to be decelerated based on a preset driving state during the delay control during cruise control. Delay when the delay control is canceled. Characterized by comprising a releasing means.

  According to the engine control apparatus of the present invention, fuel cut control can be performed at an appropriate timing while preventing control hunting during cruise control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a driving support device mounted on a vehicle, FIG. 2 is a flowchart showing a fuel cut execution control routine during engine deceleration, and FIGS. It is a timing chart which illustrates the start timing of the fuel cut in time.

  In FIG. 1, reference numeral 1 denotes a vehicle such as an automobile (own vehicle). The vehicle 1 is equipped with a cruise control system (ACC (Adaptive Cruise Control) system) 2 as an example of a vehicle driving support device. .

  The ACC system 2 includes a stereo camera 3, a stereo image recognition device 4, a travel control unit 5, and the like. The ACC system 2 basically includes a constant speed travel control in which no preceding vehicle exists. In some cases, the vehicle travels while maintaining the vehicle speed (set vehicle speed Vset) set by the driver. When there is a preceding vehicle, follow-up traveling control is performed on the preceding vehicle.

  The stereo camera 3 is composed of a pair of (left and right) CCD cameras using a solid-state image sensor such as a charge coupled device (CCD) as a stereo optical system. Are attached at regular intervals to take a stereo image of an object outside the vehicle from different viewpoints.

  An image from the stereo camera 3 is input to the stereo image recognition device 4 and, for example, from the transmission control unit (T / M_ECU) 16 through the in-vehicle communication line 18 such as CAN (Controller Area Network) communication, the own vehicle speed Vown. Etc. are input. Then, the stereo image recognition device 4 detects forward information such as three-dimensional object data and white line data ahead of the host vehicle 1 based on the image from the stereo camera 3, and determines the traveling path (own vehicle traveling path) of the host vehicle 1. presume. Further, the preceding vehicle in front of the host vehicle 1 is detected, and if there is a preceding vehicle, the preceding vehicle distance (inter-vehicle distance) Dnow, the preceding vehicle speed Vfwd (= (change amount of the inter-vehicle distance Dnow) + (own vehicle speed Vown) ), The relative speed Vrel with the preceding vehicle, the preceding vehicle deceleration Gfwd (= differential value of the preceding vehicle speed Vfwd), and the like.

  Here, the processing of the image from the stereo camera 3 in the stereo image recognition device 4 is performed as follows, for example. First, distance information is generated on the basis of the principle of triangulation from a corresponding positional deviation amount for a pair of stereo images in the traveling direction environment of the host vehicle 1 captured by the CCD camera of the stereo camera 3. Then, by performing a well-known grouping process for this distance information and comparing it with preset three-dimensional road shape data, solid object data, etc., white line data, guardrails existing along the road, Side wall data such as curbs and three-dimensional object data such as vehicles are extracted. As the three-dimensional object data, a distance to the three-dimensional object, a temporal change in the distance (relative speed with respect to the own vehicle 1), and the like are obtained. A vehicle traveling at a predetermined speed (for example, 0 km / h or more) is extracted as a preceding vehicle. A vehicle having a speed Vfwd of 0 Km / h among the preceding vehicles is recognized as a stopped preceding vehicle. Moreover, the obstacle which exists ahead of the own vehicle 1 is handled similarly to the above-mentioned preceding vehicle. Thus, in this embodiment, the stereo image recognition apparatus 4 implement | achieves the function as a preceding vehicle detection means with the stereo camera 3. FIG.

  A cruise control command switch 8 is connected to the traveling control unit 5. The cruise control command switch 8 is composed of, for example, a plurality of switches provided on the upper surface of the steering pad. Specifically, this cruise control command switch 8 is a main switch for turning cruise control ON / OFF, a vehicle speed set switch for setting a vehicle speed (set vehicle speed Vset) during constant speed traveling control, and mainly lowering the set vehicle speed Vset. The switch includes a coast switch that changes to the side, and a switch that mainly changes the set vehicle speed Vset to the ascending side. When the driver turns on the main switch and sets the desired vehicle speed (set vehicle speed Vset) with the vehicle speed set switch, a signal from the cruise control command switch 8 is input to the travel control unit 5.

  The traveling control unit 5 also receives various preceding vehicle information (such as the inter-vehicle distance Dnow, the preceding vehicle speed Vfwd, the relative speed Vrel, the preceding vehicle deceleration Gfwd, etc.) from the stereo image recognition device 4 through the in-vehicle communication line 18, for example. The Further, for example, the engine generated torque Et, the throttle opening degree θth, and the like are input from the engine control unit (E / G_ECU) 15 to the travel control unit 5 through the in-vehicle communication line 18, and the own vehicle speed Vown is also input from the T / M_ECU 16. The current gear position and the like are input.

  Based on these various pieces of input information, the traveling control unit 5 performs the opening / closing control (engine output control) of the electronically controlled throttle valve 10 through the E / G_ECU 15 and the brake control unit (BRK_ECU) during the constant speed traveling control in which no preceding vehicle exists. ) Control the output hydraulic pressure Pa from the active booster 11 through 17 (automatic intervention control of the brake 12) or shift control through the T / M_ECU 16 to converge the own vehicle speed Vown to the set vehicle speed Vset.

  The traveling control unit 5 performs follow-up traveling control when the stereo image recognition device 4 recognizes the preceding vehicle. During the follow-up running control, the running control unit 5 controls the opening / closing of the electronically controlled throttle valve 10 through the E / G_ECU 15 (engine output control), and the control of the output hydraulic pressure Pa from the active booster 11 through the BRK_ECU 17 (brake 12 Automatic intervention control) or shift control through the T / M_ECU 16 to converge the inter-vehicle distance Dnow to the target distance Dtuibi. Here, the target distance Dtuibi is variably set according to the host vehicle speed Vown or the like based on, for example, a preset map or the like.

  Here, when the host vehicle 1 is traveling, the E / G_ECU 15 determines whether or not the engine is in an idle state based on, for example, the throttle opening θth of the electronic control throttle valve 10 and the engine speed Ne. Then, when the E / G_ECU 15 determines that the electronically controlled throttle valve 10 is fully closed and the engine speed Ne is equal to or higher than the predetermined speed, and the engine is in an idle state, the E / G_ECU 15 The fuel cut control (fuel cut control during deceleration) is performed. This fuel cut control is performed both during cruise control and during non-cruise control. The E / G_ECU 15 starts the fuel cut control after the engine is in an idle state. (Delay time T) is set to a different time for cruise control control and non-cruise control control. Specifically, the E / G_ECU 15 sets the delay time T1 during the cruise control control during the non-cruise control control in order to prevent control hunting during which the fuel cut control and the fuel recovery are repeated in a short cycle during the cruise control control. A time relatively longer than the delay time T2 (for example, T1 = 5 seconds) is set.

  On the other hand, the E / G_ECU 15 detects the preset driving state of the host vehicle 1 during the delay control from the determination of the idle state to the start of the fuel cut control during the cruise control. When the necessity of clear deceleration of the host vehicle 1 is recognized based on the driving state, the delay control is canceled and the routine immediately shifts to the fuel cut control. Specifically, the E / G_ECU 15 determines that the own vehicle speed Vown is set to the set vehicle speed when, for example, a coasting instruction for changing the set vehicle speed Vset to the low speed side is made through the constant speed travel switch 8 during the delay time during cruise control control. When the set value α is higher than Vset, when the BRK_ECU 17 performs automatic intervention control (automatic brake control) of the brake 12, or when the automatic transmission is shifted down, the vehicle 1 If an obvious deceleration request (necessity of deceleration) can be recognized based on the operating state, the delay control is canceled and the routine proceeds to fuel cut control.

  Thus, in the present embodiment, the E / G_ECU 15 has functions as an idle determination unit, a fuel cut unit, a delay control unit, a delay time setting unit, and a delay release unit.

  Next, engine deceleration fuel cut execution control executed by the E / G_ECU 15 will be described with reference to the deceleration fuel cut execution control routine shown in FIG.

  This routine is repeatedly executed every predetermined time. When the routine starts, the E / G_ECU 15 first determines whether or not the fuel cut control (deceleration fuel cut control) is currently being performed on the engine in step S101. Check out.

  If it is determined in step S101 that the fuel cut control is currently being performed, the E / G_ECU 15 proceeds to step S113 and checks whether or not a preset return condition from the fuel cut control is satisfied. If the E / G_ECU 15 determines that the return condition is not satisfied, the E / G_ECU 15 directly exits the routine. On the other hand, if the E / G_ECU 15 determines that the return condition is satisfied, the E / G_ECU 15 proceeds to step S114 and cancels the combustion cut control. After (fuel recovery), exit the routine.

  On the other hand, if it is determined in step S101 that the fuel cut control is not being performed, the E / G_ECU 15 proceeds to step S102 and checks whether or not the engine is currently in an idle state. As a result, when it is determined in step S102 that the engine is not in the idle state, the E / G_ECU 15 directly exits the routine.

  On the other hand, when it is determined in step S102 that the electronically controlled throttle valve 10 is currently fully closed and the engine speed Ne is equal to or higher than the predetermined speed and the engine is in an idle state, the E / G_ECU 15 It is checked whether or not the cruise control is currently under control.

  If it is determined in step S103 that the cruise control control is not currently being performed (that is, the non-cruise control control is being performed), the E / G_ECU 15 proceeds to step S104 to cut the fuel after the engine is in an idle state. T2 is set as a delay time until control is started.

  Then, when the process proceeds from step S104 to step S105, the E / G_ECU 15 checks whether or not the elapsed time Tidl from when the engine is in the idle state is equal to or longer than the delay time T2, and the elapsed time Tidl is still set to the delay time T2. If it is determined that it has not been reached, the process waits as it is.

  On the other hand, if it is determined in step S105 that the elapsed time Tidl is equal to or longer than the delay time T2, the E / G_ECU 15 proceeds to step S112 and starts fuel cut control for the engine, and then exits the routine.

  If it is determined in step S103 that the cruise control is currently being performed, the E / G_ECU 15 proceeds to step S106, where T1 (delay time from when the engine becomes idle until the fuel cut control is started is T1 ( > T2) is set.

  Then, when proceeding from step S106 to step S107, the E / G_ECU 15 determines whether or not to cancel the delay control until the fuel cut control is started by the processing up to step S110.

  That is, the E / G_ECU 15 first checks in step S107 whether or not a coasting instruction for changing the set vehicle speed Vset to the low speed side is made by the driver through the constant speed travel switch 8.

  As a result, when the coast instruction is given by the driver, the E / G_ECU 15 determines that the delay control cancellation condition is satisfied, proceeds to step S112, starts the fuel cut control, and then exits the routine.

  That is, when the coast instruction is given by the driver, the set vehicle speed Vset itself is changed to the low speed side, so that it is considered that the fuel cut control is canceled (fuel recovery) immediately after the fuel cut control is executed. It is difficult to generate control hunting. In addition, if fuel cut control is started after a predetermined delay time after the coast instruction is given, there is a possibility that the behavior of the vehicle with respect to the coast instruction is delayed, and the driver may feel uncomfortable. Therefore, when the coast instruction is given by the driver, the E / G_ECU 15 determines that an obvious deceleration request has been recognized, cancels the delay control, and starts the fuel cut control.

  Thus, for example, as shown in FIG. 5, when the coast instruction is given by the driver and the set vehicle speed Vset is changed to the low speed side before the delay time T1 elapses after the engine idle state is determined. Can quickly shift to the fuel cut control during deceleration, and the own vehicle speed Vown with respect to the new set vehicle speed Vset as compared with the case where the delay control is not canceled (see the two-dot chain line in FIG. 5A). Can be quickly converged.

  On the other hand, if it is determined in step S107 that the coast instruction has not been given, the E / G_ECU 15 proceeds to step S108, where the current host vehicle speed Vown is higher than the set vehicle speed Vset by a set value α (for example, α = 3 to 5 km). / H) It is checked whether or not it has become higher.

  As a result, if Vown ≧ Vset + α, the E / G_ECU 15 determines that the delay control cancellation condition has been established, proceeds to step S112, starts fuel cut control, and then exits the routine.

  That is, when the host vehicle speed Vown is sufficiently higher than the set vehicle speed Vset, it is unlikely that the fuel cut control is canceled (fuel recovery) immediately after the fuel cut control is executed, and control hunting occurs. The possibility is low. Moreover, if the host vehicle speed Vown becomes too high with respect to the set vehicle speed Vset, the driver may feel uncomfortable. Therefore, when Vown ≧ Vset + α, the E / G_ECU 15 determines that an obvious deceleration request has been recognized, cancels the delay control, and starts the fuel cut control.

  As a result, for example, as shown in FIG. 4, before the delay time T1 elapses after the idling state of the engine is determined, the gradient of the vehicle traveling path increases in the downward direction (from a gentle gradient to a steep gradient). When the own vehicle speed Vown becomes sufficiently higher than the set vehicle speed Vset, it is possible to quickly shift to the fuel cut control during deceleration, and the vehicle speed overshoot (FIG. 4A) Etc.) can be accurately prevented.

  On the other hand, if it is determined in step S108 that Vown <Vset + α, the E / G_ECU 15 proceeds to step S109 and checks whether or not the automatic brake control intervention by the BRK_ECU 17 is currently being performed.

  As a result, if the automatic brake control has been intervened, the E / G_ECU 15 determines that the delay control cancellation condition has been satisfied, proceeds to step S112, starts the fuel cut control, and then exits the routine.

  That is, as the case where the automatic brake control is performed, for example, the case where the host vehicle 1 is approaching the preceding vehicle during the follow-up traveling control is assumed. In such a case, the fuel cut control is performed. It is unlikely that the fuel cut control is canceled (fuel recovery) immediately after the execution. Moreover, in cruise control control, the intervention of automatic brake control is generally performed only when sufficient deceleration cannot be obtained by deceleration through throttle control. Therefore, when the automatic brake control is intervened, the E / G_ECU 15 determines that an obvious deceleration request has been recognized, cancels the delay control, and starts the fuel cut control.

  On the other hand, if it is determined in step S109 that the automatic brake control has not been intervened, the E / G_ECU 15 proceeds to step S110, and whether or not it is immediately after the transmission downshift control by the T / M_ECU 16 is completed. Check out.

  As a result, if it is immediately after the completion of the downshift control, the E / G_ECU 15 determines that the delay control cancellation condition is satisfied, proceeds to step S112, starts the fuel cut control, and then exits the routine.

  That is, when the transmission is downshifted when the engine is in an idle state, it is assumed that sufficient deceleration due to engine braking has not been obtained at the current shift stage. It is unlikely that the fuel cut control is canceled (fuel recovery) immediately after the control is executed. Therefore, when the transmission downshift control is performed, the E / G_ECU 15 determines that an obvious deceleration request has been recognized, cancels the delay control, and starts the fuel cut control.

  On the other hand, if it is determined in step S110 that it is not immediately after the completion of the downshift control, the E / G_ECU 15 proceeds to step S111, and whether or not the elapsed time Tidl after the engine is in the idle state is equal to or longer than the delay time T1. If it is determined that the elapsed time Tidl has not yet reached the delay time T1, the process returns to step S107.

  On the other hand, if it is determined in step S111 that the elapsed time Tidl is equal to or longer than the delay time T1, the E / G_ECU 15 proceeds to step S112, starts fuel cut control for the engine, and then exits the routine.

  As a result, for example, as shown in FIG. 3, when the vehicle travels on a gentle slope in the downward direction, the fuel cut control during deceleration and the fuel recovery may be repeated with a relatively long cycle. Thus, control hunting during cruise control control can be accurately prevented.

  In order to reduce a shock caused by a sudden torque fluctuation, the E / G_ECU 15 does not start the fuel cut for all the cylinders at the same time at the start of the fuel cut control in the above-described step S112. Alternatively, it is desirable to start the fuel cut at a slightly different timing for each cylinder group.

  According to such an embodiment, when it is determined that the engine is in an idle state during cruise control, the shift to fuel cut control is performed via delay control using a relatively longer delay time than during non-cruise control. By doing so, it is possible to accurately prevent control hunting due to repeated fuel cut control and fuel recovery in a short cycle. In this case, when the necessity of deceleration is recognized based on the driving state of the vehicle 1 set in advance during cruise control, the delay time is set longer by canceling the delay control and shifting to the fuel cut control. In this case, the fuel cut control can be performed at an appropriate timing while avoiding a control delay in a predetermined operation state.

  In the above-described embodiment, the cruise control function with the inter-vehicle distance control (following travel control) function has been described as the cruise control (ACC) function, but the cruise control function applied to the present invention is limited to this. For example, a cruise control function that does not include an inter-vehicle distance control function may be used. That is, the cruise control function in the present invention is understood in a broad sense.

Schematic configuration diagram of a driving support device mounted on a vehicle Flowchart showing engine cut fuel cut execution control routine Timing chart illustrating fuel cut start timing during cruise control Timing chart illustrating fuel cut start timing during cruise control Timing chart illustrating fuel cut start timing during cruise control

Explanation of symbols

1 ... Vehicle (own vehicle)
DESCRIPTION OF SYMBOLS 2 ... Driving support system 3 ... Stereo camera 4 ... Stereo image recognition apparatus 5 ... Traveling control unit 8 ... Cruise control command switch 10 ... Electronically controlled throttle valve 11 ... Active booster 12 ... Brake 15 ... Engine control unit (idle judging means, fuel) Cutting means, delay control means, delay time setting means, and delay release means)
16 ... Transmission control unit 17 ... Brake control unit 18 ... In-vehicle communication line Dnow ... Inter-vehicle distance Dtuibi ... Target distance Et ... Engine generated torque Gfwd ... Preceding vehicle deceleration Ne ... Engine speed Pa ... Output hydraulic pressure T1 ... Delay time (cruise) During control)
T2 ... Delay time (during non-cruise control)
Tidl… elapsed time Vfwd… preceding vehicle speed Vfwd… speed Vown… own vehicle speed Vrel… relative speed Vset… set vehicle speed α… set value θth… throttle opening

Claims (5)

An idle determination unit that is mounted on a vehicle having a cruise control function and that determines whether or not the engine is in an idle state during traveling, and a fuel cut unit that performs fuel cut control on the engine when the engine is in an idle state And delay control means for performing delay control from when the engine is in an idle state until fuel cut control is started, and a delay time related to the delay control during cruise control from the delay time during non-cruise control A delay time setting means for setting a longer time, and an engine control device comprising:
An engine comprising: a delay canceling means for canceling the delay control when the necessity of deceleration is recognized based on a preset driving state of the host vehicle during the delay control during cruise control. Control device.   2. The engine according to claim 1, wherein the delay canceling unit cancels the delay control when a coasting instruction for changing a set vehicle speed for constant speed traveling to a low speed side is given during the delay time. Control device.   3. The delay canceling unit cancels the delay control when the own vehicle speed during the delay time is higher than a set vehicle speed for a constant speed traveling by a set value or more. Engine control device.   The engine control according to any one of claims 1 to 3, wherein the delay canceling unit cancels the delay control when an automatic brake intervention is performed during the delay time. apparatus.   5. The engine control device according to claim 1, wherein the delay canceling unit cancels the delay control when the automatic transmission is shifted down during the delay time. 6.

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