JP2006312924A - Cruise controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cruise controller making a target speed more properly follow an actual vehicle speed when carrying out cruise control. <P>SOLUTION: In step S14, force acting in a traveling direction of a vehicle is calculated on the basis of acceleration (a) of the vehicle. In step 16, driving force necessary for maintaining the vehicle at the target speed is calculated on the basis of a difference between the vehicle speed and the target speed, and the force acting on the vehicle. In step S22, the calculated driving force is distributed between an output of an engine, and braking force of an ABS. In steps S24 and S26, setting is carried out such that the distributed output and braking force are obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cruise control device that performs cruise control that causes a vehicle to travel at a constant speed so as to follow a set target speed.

  2. Description of the Related Art A cruise control device that performs control to maintain a vehicle traveling speed, that is, a vehicle speed at a constant speed based on an instruction to perform cruise control by a user through operation of a cruise control switch is generally known. In such a cruise control device, control for feeding back the vehicle speed to the target speed is performed during cruise control.

  Further, as can be seen in Patent Document 1 below, a cruise control device that performs fuel cut when the vehicle speed exceeds a target speed, such as when the vehicle approaches a downhill, has also been proposed. When the fuel cut is performed, the braking force is applied to the vehicle by the engine brake, so that the vehicle can be decelerated. Further, in this cruise control device, the vehicle speed is controlled to the target speed by repeating fuel cut and combustion control. That is, according to this control, the actual vehicle speed follows the target speed while fluctuating in synchronization with intermittent repeated fuel cuts.

By the way, when the vehicle speed is made to follow the target speed by intermittently repeating the fuel cut by the cruise control device, it is required to hunt the vehicle speed at a level that is not experienced by the user, so that adaptation becomes difficult. ing. Furthermore, since the variation mode of the vehicle speed when the fuel cut is intermittently repeated on the downhill depends greatly on the gradient of the downhill, even if the above-described adaptation can be performed at a predetermined gradient, There is a risk that proper control may not be possible on downhills with different slopes.
JP-A-7-315074

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cruise control device that can appropriately follow an actual vehicle speed with a target speed in cruise control.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to a first aspect of the present invention, there is provided a cruise control apparatus for performing cruise control for causing a vehicle to travel at a constant speed so as to follow a set target speed. In the cruise control, the detection means for detecting acceleration of the vehicle, Control means for controlling the driving force of the vehicle so as to cancel the force acting in the traveling direction of the vehicle based on the acceleration of the vehicle detected by the detecting means.

  Depending on the traveling environment of the vehicle, a force may be applied to the vehicle, such as a gravitational acceleration applied to the traveling direction of the vehicle. The driving force required to make the detected value of the vehicle speed follow the target speed depends on the force applied to the vehicle. In other words, the driving force of the vehicle required to make the detected value of the vehicle speed follow the target speed is not uniquely determined by the difference between the detected value of the vehicle speed and the target speed, but depends on the force applied to the vehicle. On the other hand, since acceleration is applied to the vehicle by the force applied to the vehicle, the force applied to the traveling direction of the vehicle can be estimated from the acceleration of the vehicle. For this reason, it is possible to comprehend the driving force required to cancel the force acting in the traveling direction of the vehicle and to make the vehicle speed follow the target speed by the acceleration of the vehicle.

  In this regard, in the above-described configuration, by using the detected value of the acceleration of the vehicle, the driving of the vehicle is generated so as to generate the driving force required to cancel the force acting in the traveling direction of the vehicle and make the vehicle speed follow the target speed. The power can be controlled.

  The driving force includes a negative driving force, in other words, a braking force.

  According to a second aspect of the present invention, in the first aspect of the invention, when the difference between the speed of the vehicle and the target speed is the same, the control means increases the driving force of the vehicle as the acceleration of the vehicle increases. The driving force is controlled to be small.

  Even if the difference between the vehicle speed and the target speed is the same, the greater the acceleration of the vehicle, the greater the braking force required to decelerate the vehicle (the driving force is small (negative Value)).

  In this regard, in the above configuration, it is possible to control the driving force to be appropriate according to the acceleration of the vehicle.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control unit calculates a driving force required for the vehicle based on the detected value, and the calculated driving. Operating means for operating the vehicle based on the force, and controlling the driving force of the vehicle.

  In the above configuration, the driving force required for the vehicle is calculated based on the detected value of the acceleration of the vehicle. For this reason, the vehicle can be appropriately operated according to the calculated driving force.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the driving force calculation means calculates a force acting in the traveling direction of the vehicle by multiplying the detected value of the acceleration by the total weight of the vehicle. Means, and means for calculating the required driving force based on the driving force required to cancel the calculated force.

  A product obtained by multiplying the acceleration by the total weight of the vehicle can be considered as a force acting in the traveling direction of the vehicle. And, in order to make the vehicle speed run at a constant speed at the target speed, it is necessary to cancel the force acting in the running direction of the vehicle. In this regard, in the above configuration, by calculating the required driving force based on the driving force necessary for canceling the force acting on the vehicle, an appropriate driving force for driving the vehicle at a constant speed at the target speed is obtained. Obtainable.

  According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the vehicle includes a multi-cylinder internal combustion engine as a prime mover, and the operating means burns in accordance with the calculated driving force. The number of cylinders of the internal combustion engine to be controlled is variably set.

  The internal combustion engine can control the output substantially continuously up to the maximum output with the output in the idle state as a lower limit. However, since the output in the idle state is a lower limit, a large gap is created between the stop of the combustion control by the fuel cut and the output in the idle state.

  In this regard, in the above configuration, since the number of cylinders on which combustion control is performed is variably set, an output smaller than the output in the idle state can be generated in stages.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the operating means is responsive to the required driving force, in addition to the variable setting of the number of cylinders, the air-fuel ratio and ignition timing of the internal combustion engine. It is characterized in that at least one of the variable operations is performed.

  In the above configuration, although the output of the internal combustion engine changes stepwise by the variable setting of the number of cylinders, the output cannot be continuously adjusted. Here, in the above configuration, the air-fuel ratio and the ignition timing are variably operated. For example, since the output decreases when the air-fuel ratio is made lean, the output that changes stepwise by the variable setting of the number of cylinders can be further finely adjusted by performing the lean operation. Further, for example, since the output decreases by retarding the ignition timing, the output that changes stepwise by the variable setting of the number of cylinders can be further finely adjusted by performing a variable operation of the ignition timing.

  According to a seventh aspect of the present invention, in the sixth aspect of the invention, the apparatus further comprises a detecting means for detecting a state of a catalyst that purifies the exhaust gas of the internal combustion engine, and the operating means is responsive to the required driving force. , Variable setting of the number of cylinders, variable operation of the air-fuel ratio, and variable operation of the ignition timing, and the variable operation amount of the air-fuel ratio and the ignition for obtaining the required driving force The variable operation amount of the time is determined according to the state of the catalyst.

  In the above configuration, the variable operation amount of the air-fuel ratio and the variable operation amount of the ignition timing for generating the required driving force are determined according to the state of the catalyst such as the oxygen storage amount of the catalyst, for example. Therefore, it is possible to generate the required driving force while avoiding the air-fuel ratio that causes the exhaust characteristics to deteriorate.

  The invention according to claim 8 is the invention according to claim 3 or 4, wherein the vehicle includes a braking unit that controls a braking force of the vehicle, and the operation unit is configured to perform the operation according to the calculated driving force. The braking means is operated.

  According to the above configuration, the braking force can be obtained by operating the actuator that generates the braking force of the vehicle.

  The invention according to claim 9 is the invention according to any one of claims 5 to 7, wherein the vehicle includes a braking unit that controls a braking force of the vehicle, and the cruise control device includes the driving force calculation unit. Is further provided with means for distributing the driving force calculated by the motor to the output of the prime mover and the braking force of the braking means, and the operating means operates at least one of the prime mover and the braking means based on the distributed driving force. It is characterized by doing.

  In the above configuration, the driving force calculated by the driving force calculation means is distributed between the output of the multi-cylinder internal combustion engine that is the prime mover and the braking force of the braking means. For this reason, when the calculated driving force is negative, it is possible to obtain a larger braking force as compared with the case where only the engine brake is used as the braking force, and thus to more appropriately control the driving force of the vehicle. Can do.

  According to a tenth aspect of the present invention, there is provided a cruise control apparatus that performs cruise control for causing a vehicle to travel at a constant speed so as to follow a set target speed, so that the speed of the vehicle follows the target speed in the cruise control. And a control means for variably setting the number of cylinders in which the combustion control is performed in the multi-cylinder internal combustion engine mounted on the vehicle so as to generate the calculated driving force. It is characterized by that.

  The internal combustion engine can control the output substantially continuously up to the maximum output with the output in the idle state as a lower limit. However, since the output in the idle state is a lower limit, a large gap is created between the stop of the combustion control by the fuel cut and the output in the idle state.

  In this regard, in the above configuration, since the number of cylinders on which combustion control is performed is variably set, an output smaller than the output in the idle state can be generated in stages, and thus the calculated driving force can be appropriately generated. can do.

  According to an eleventh aspect of the present invention, in the invention according to the tenth aspect, in addition to the variable setting of the number of cylinders, the control unit is configured to generate an empty space for the internal combustion engine so as to generate the driving force calculated by the calculation unit. A variable operation of at least one of the fuel ratio and the ignition timing is performed.

  In the above configuration, although the output of the internal combustion engine changes stepwise by the variable setting of the number of cylinders, the output cannot be continuously adjusted. Here, in the above configuration, the air-fuel ratio and the ignition timing are variably operated. For example, since the output decreases when the air-fuel ratio is made lean, the output that changes stepwise by the variable setting of the number of cylinders can be further finely adjusted by performing the lean operation. Further, for example, since the output decreases by retarding the ignition timing, the output that changes stepwise by the variable setting of the number of cylinders can be further finely adjusted by performing a variable operation of the ignition timing.

  A twelfth aspect of the invention according to the eleventh aspect is further provided with a detecting means for detecting a state of a catalyst for purifying exhaust gas of the internal combustion engine, wherein the control means is responsive to the required driving force. , Variable setting of the number of cylinders, variable operation of the air-fuel ratio, and variable operation of the ignition timing, and the variable operation amount of the air-fuel ratio and the ignition for obtaining the required driving force The variable operation amount of the time is determined according to the state of the catalyst.

  In the above configuration, the variable operation amount of the air-fuel ratio and the variable operation amount of the ignition timing for generating the required driving force are determined according to the state of the catalyst such as the oxygen storage amount of the catalyst, for example. Therefore, it is possible to generate the required driving force while avoiding the air-fuel ratio that causes the exhaust characteristics to deteriorate.

(First embodiment)
Hereinafter, a first embodiment in which a cruise control device according to the present invention is applied to a vehicle equipped with a gasoline engine will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the vehicle.

  As shown in the figure, the output of the engine 2, which is a multi-cylinder internal combustion engine, is transmitted to the drive wheels 8 of the vehicle via the torque converter 4 and the transmission 6. A brake 10 for braking the drive wheel 8 is provided in the vicinity of the drive wheel 8. The braking force of the brake 10 is adjusted by adjusting the brake hydraulic pressure by the hydraulic actuator 12.

  FIG. 2 shows the configuration of the engine 2. As shown in the figure, an air flow meter 42 for detecting the air flow rate is provided upstream of the intake passage 40 of the engine 2. Further, an electronically controlled throttle valve 46 driven by a motor 44 is provided downstream thereof. Further, a fuel injection valve 48 is provided downstream thereof. The air-fuel mixture in the intake passage 40 flows into the combustion chamber 52 when the intake valve 50 is opened. The air-fuel mixture in the combustion chamber 52 is ignited by the spark plug 54 and used for combustion. The air-fuel mixture subjected to combustion is discharged as exhaust gas to the exhaust passage 58 by opening the exhaust valve 56. The exhaust passage 58 is provided with a catalyst 60 for purifying exhaust gas. An air-fuel ratio sensor 62 is provided upstream of the catalyst 60 in the exhaust passage 58, and an oxygen sensor 64 is provided downstream of the catalyst 60. Incidentally, the air-fuel ratio sensor 62 is a sensor having an output characteristic substantially proportional to the oxygen concentration, and the oxygen sensor 64 is a sensor having a substantially binary output characteristic depending on whether the oxygen concentration is lower or higher than a predetermined concentration. is there.

  The engine 2 is operated by an engine control device 20 (EMS ECU in the figure). The engine control device 20 includes a central processing unit and an appropriate memory. The motor 44, fuel injection valve 48, spark plug 54, etc. are used to control the opening of the throttle valve 46, the ignition timing, the fuel injection amount, etc. based on the detection values of various sensors that detect the operating state of the engine 2. The various actuators of the engine 2 are operated. In particular, in the present embodiment, a constant speed that targets the traveling speed (vehicle speed) of the vehicle based on an instruction to perform cruise control by the user through the operation of the cruise control switch 24 shown in FIG. Cruise control to keep at (target speed).

  The hydraulic actuator 12 shown in FIG. 1 is operated by an ABS control device 22 (ABS ECU in the figure). The ABS control device 22 includes a central processing unit and an appropriate memory. Then, the hydraulic actuator 12 is operated to perform braking control based on the detection value of the wheel speed sensor 14 that detects the rotational speed of the drive wheel 8. Incidentally, an anti-lock brake system (ABS) is configured by including the brake 10, the hydraulic actuator 12, the ABS control device 22, and the like.

  The engine control device 20 and the ABS control device 22 communicate with each other.

  Here, the cruise control according to the present embodiment will be described with reference to FIG. FIG. 3 shows a procedure of cruise control processing according to the present embodiment. The process shown in FIG. 3 is repeatedly executed by the engine control device 20 with a predetermined cycle, for example, while communicating with the ABS control device 22.

  In this series of processing, first, in step S10, the difference between the vehicle speed detected by the wheel speed sensor 14 and the target speed is calculated. In the subsequent step S12, the vehicle acceleration a is detected based on the detection value of the wheel speed sensor 14 (specifically, the vehicle acceleration a is estimated and calculated as a time differential value of the vehicle speed detected by the wheel speed sensor 14). . Further, in step S14, a force acting in the traveling direction of the vehicle is calculated. Here, the force acting in the traveling direction of the vehicle is calculated as ma by multiplying the acceleration a detected in step S12 by the total vehicle weight m. Incidentally, the vehicle total weight m may be a value described in the specification in advance as the total vehicle weight. However, when the vehicle includes a sensor that detects whether or not the user is seated on the seat of the vehicle, a value corrected according to the number of users detected to be sitting on the seat is a vehicle total weight m. It is good.

  In the subsequent step S16, the driving force necessary to keep the vehicle at the target speed is calculated based on the difference between the detected value of the vehicle speed and the target speed and the force acting in the traveling direction of the vehicle. Here, in calculating the driving force necessary to keep the vehicle speed at the target speed, the force acting in the traveling direction of the vehicle is used for the following reason.

  FIG. 4 shows the time when the vehicle 30 travels on a downhill with an inclination angle θ. In this case, the gravitational acceleration g has a traveling direction component of the vehicle 30. For this reason, as shown in FIG. 4, when the vehicle 30 travels downhill, an extra force (= mg × sin θ = ma) is applied to the vehicle 30 compared to when the vehicle 30 travels on flat ground. For this reason, even if the difference between the vehicle speed of the vehicle 30 and the target speed is the same, the driving force required to cause the vehicle speed to follow the target speed is different.

  Therefore, in the present embodiment, a force ma acting in the traveling direction of the vehicle 30 is calculated based on the acceleration a of the vehicle 30, and a driving force required by the vehicle 30 is calculated based on the force ma. Thus, even if the difference between the vehicle speed and the target speed is the same, control is performed so as to generate different driving forces when the acceleration of the vehicle 30 is different. FIG. 5 illustrates a case where the difference between the vehicle speed and the target speed is the same and the acceleration of the vehicle 30 is different. Here, the case where the vehicle traveling while decelerating (case k1) and the vehicle traveling while accelerating (case k2) have the same vehicle speed at time t1 and there is a difference ΔV between the target speed and the case. In this case, the braking force required to make the vehicle speed follow the target speed in the case k2 is larger than that in the case k1.

  For this reason, in this embodiment, even if the difference between the vehicle speed and the target speed is the same, control is performed so that the driving force of the vehicle decreases as the acceleration of the vehicle increases. Here, the driving force includes a negative driving force. In other words, it also includes a braking force.

  Specifically, the calculation of the driving force is performed, for example, by adding a force “−ma” required to cancel the force ma applied to the vehicle and a feedback amount determined based on a difference between the vehicle speed and the target speed. You should do it.

  In the subsequent step S18, the maximum value and the minimum value of the output of the engine 2 obtained within a predetermined period are estimated. Here, the maximum value of the output of the engine 2 is determined for a predetermined period from the current operating state, for example, when the fuel injection amount is such that the throttle valve opening is maximized and the torque of the engine 2 is maximized. It shall be obtained within. This is generally different from the maximum output of the engine 2. That is, even if the opening degree of the throttle valve 46 is maximized, there is a response delay until the amount of air charged in the combustion chamber of the engine 2 is maximized. In this step S18, the processing cycle shown in FIG. 3 is set as a predetermined period, and the maximum value of the output of the engine 2 that can be realized within this predetermined period is estimated. Further, the minimum value of the output of the engine 2 is, for example, the maximum value within a predetermined period of the braking force (negative driving force) by the engine brake by cutting the fuel of the engine 2. That is, the maximum value of the braking force by the engine brake obtained after the fuel cut is performed until the next cycle of the process of FIG.

  In the subsequent step S20, the maximum value and the minimum value of the braking force due to the operation of the hydraulic actuator 12 are estimated. The maximum value and the minimum value of the braking force by the operation of the hydraulic actuator 12 are the maximum value and the minimum value of the braking force by the operation of the hydraulic actuator 12 by the ABS control device 22. As for this braking force, since the upper limit of the braking force is variably set in accordance with the acceleration state of the vehicle in the antilock brake system, the maximum value and the minimum value are estimated in step S20.

  In the subsequent step S22, the driving force calculated in step S16 is divided into the output of the engine 2 and the braking force of the brake 10 by operating the hydraulic actuator 12 by the ABS control device 22. This distribution is set so that appropriate driving force can be controlled. That is, for example, when the driving force is generated only by the output of the engine 2, the braking force that is a negative driving force is limited to the force of the engine brake, so that the braking force is limited. On the other hand, when combined with the operation of the hydraulic actuator 12 by the ABS control device 22, a larger braking force can be realized, and thus the driving force can be controlled more appropriately. Specifically, for example, when the driving force calculated in step S16 is negative, in other words, when the braking force is required, the braking force by the antilock brake system and the engine brake by the engine 2 are combined. Use it. If the driving force calculated in step S16 is positive, the allocation amount of the antilock brake system may be “0”.

  In step S24, the throttle opening degree, the ignition timing, and the fuel injection amount for realizing the driving force distributed to the engine 2 are set. Here, the above setting is made based on the output of the engine 2 that generates the distributed driving force. That is, the driving force is a force generated by the driving wheel 8 and can be converted into an output torque required for the engine 2 by taking into account conversion by the transmission 6 and the torque converter 4. If the output torque required for the engine 2 is known, the throttle valve opening, ignition timing, and fuel injection amount can be set based on the output torque.

  Incidentally, in the present embodiment, control for variably setting the number of cylinders of the engine 2 that performs the combustion control in order to fill a gap between the output when the engine 2 is idle and the output when the fuel is cut (braking force by the engine brake). Then, the ignition timing is variably controlled. This will be described with reference to FIG.

  In FIG. 6, the horizontal axis represents the intake air amount, and the vertical axis represents the output of the engine 2. On the higher load side than during idling, the output of the engine 2 can be increased continuously by increasing the intake air amount continuously. On the other hand, as shown in FIG. 6 where the fuel cut is performed for all cylinders, a large gap occurs in the output of the engine 2 between the idle operation and the fuel cut. Therefore, in this embodiment, the number of cylinders for which combustion control is performed is variably set in order to fill the output gap between the idle operation and the all-cylinder fuel cut. By variably setting the number of cylinders for performing combustion control in this way, it is possible to obtain an output that is smaller than the output of the engine 2 that is idling using all the cylinders and larger than the output when the fuel of all the cylinders is cut. it can.

  Specifically, in order to fill the output gap between the idle operation and the all-cylinder fuel cut, in addition to the variable setting of the number of cylinders, a variable operation of the ignition timing is performed. This is because the output of the engine 2 can be adjusted stepwise by variable setting of the number of cylinders, but cannot be continuously adjusted. In this respect, the output torque can be finely adjusted by changing the ignition timing. FIG. 7 shows the relationship between the efficiency of the output torque of the engine 2 and the ignition timing. Here, the efficiency is defined as the ratio of the output torque at each ignition timing to the output torque when the ignition timing is MBT under the condition that the intake air amount and air-fuel ratio of the engine 2 are fixed. Here, MBT is an ignition timing that maximizes the output of the engine. As shown in the figure, the efficiency of the output torque decreases as the ignition timing is retarded, and the efficiency of the output torque can be continuously changed by continuously changing the ignition timing. For this reason, if the ignition timing is variably operated, the output torque of the engine 2 can be finely adjusted.

  Therefore, in addition to the variable setting of the number of cylinders, a variable operation of the ignition timing is performed. Specifically, from the output torque obtained by MBT in an arbitrary number of cylinders (> 0) to the output torque obtained by MBT when one cylinder is reduced from that (all cylinder fuel cut in the case of 0 cylinders) An arbitrary output torque is generated by operating the ignition timing on the retard side with respect to the MBT.

  Specifically, as shown in FIG. 8, the operation is performed with one cylinder from the output when all cylinders are cut to the output when the three cylinders are cut and the ignition timing is advanced to MBT. Is done. Since the output can be lowered by retarding the ignition timing from MBT, an output that is larger than the output when all cylinders are fuel cut and smaller than the maximum idle output during one-cylinder operation is required. When the ignition timing is set, the control is performed to obtain the required output by operating the ignition timing to the retard side of the MBT.

  Similarly, the operation is performed in two cylinders from the maximum output when the one cylinder operation is performed to the output when the two cylinder fuel cut is performed and the ignition timing is advanced to MBT. Further, the operation is performed in the three cylinders from the maximum output when the two-cylinder operation is performed to the output when the one-cylinder fuel cut is performed and the ignition timing is advanced to the MBT.

  As described above, by performing the variable operation of the ignition timing in addition to the variable setting of the number of cylinders, the output of the engine 2 can accurately follow the required output.

  On the other hand, in step S26 of FIG. 3, the hydraulic actuator 12 is operated to realize the braking force distributed to the ABS. Specifically, information on the distributed braking force is sent from the engine control device 20 to the ABS control device 22, and the hydraulic actuator 12 is operated by the ABS control device 22.

  In addition, when the process of step S26 is completed, this series of processes is once complete | finished.

  Here, the effect | action of the process of FIG. 3 is demonstrated based on FIG.

  Fig.9 (a) shows sectional drawing about a road shape. FIG. 9B shows the transition of the vehicle speed in the present embodiment, and FIG. 9C shows the transition of the driving force in the present embodiment. FIG. 9D shows the transition of the vehicle speed according to the conventional technique, and FIG. 9E shows the transition of the driving force according to the conventional technique.

  As shown in FIG. 9 (c), by combining the variable setting of the number of cylinders for which combustion control is performed and the retarding operation of the ignition timing (and further combining the operation of the hydraulic actuator 12), the engine 2 Can be smoothly changed. And, by calculating the driving force required for the vehicle and controlling the driving force based on this, the vehicle speed once exceeds the target speed indicated by the alternate long and short dash line in the figure when the vehicle enters the downhill. , Immediately follows the target speed.

  On the other hand, when the vehicle speed is controlled to the target speed by repeating the fuel cut of all cylinders and the combustion of all cylinders as shown in FIG. 9 (e), the driving force as shown in FIG. 9 (d). Changes intermittently.

  According to the embodiment described above in detail, the following effects can be obtained.

  (1) During cruise control, the driving force required for the vehicle is calculated based on the acceleration a of the vehicle. For this reason, it is possible to control the driving force of the vehicle so as to cancel the force acting in the traveling direction of the vehicle and generate the driving force necessary to make the vehicle speed follow the target speed.

  (2) Even if the difference between the vehicle speed and the target speed is the same, the driving force is controlled so that the driving force of the vehicle decreases as the acceleration a of the vehicle increases. Thereby, it can control to a suitable driving force according to the acceleration a of a vehicle.

  (3) The force acting on the vehicle is calculated by multiplying the acceleration weight a by the total weight m of the vehicle, and the required driving force is calculated based on the driving force necessary to cancel the calculated force. . As a result, it is possible to obtain an appropriate driving force for driving the vehicle at a constant speed at the target speed.

  (4) The number of cylinders of the engine 2 on which combustion control is performed according to the required driving force is variably set. For this reason, an output smaller than the output in the idle state can be generated in stages.

  (5) The ignition timing is variably operated in accordance with the variable setting of the number of cylinders for which combustion control is performed. Thereby, the output which changes in steps by the variable setting of the number of cylinders can be further finely adjusted.

  (6) The hydraulic actuator 12 was operated according to the required driving force (braking force). Thereby, compared with the case where the braking force of the vehicle is obtained only by the engine brake, a larger braking force can be realized, and as a result, the driving force of the vehicle can be controlled more appropriately.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, when the number of cylinders is variably set, the output of the engine 2 is adjusted by performing a variable operation of the air-fuel ratio in addition to a variable operation of the ignition timing.

  That is, as shown in FIG. 10, the efficiency of the output torque of the engine 2 varies depending on the air-fuel ratio. Here, the efficiency is obtained by quantifying the ratio of the engine output when the ignition timing and the intake air amount are fixed with respect to the value when the air-fuel ratio is the theoretical air-fuel ratio (λ = 1). is there.

  FIG. 11 shows a cruise control procedure according to this embodiment. This process is repeatedly executed by the engine control device 20 at a predetermined cycle, for example.

  In this series of processing, first, processing from steps S10 to S16 shown in FIG. 3 is performed. The processing in step S16 is step S30 in FIG.

  In the subsequent step S32, it is determined whether or not the output of the engine 2 corresponding to the required driving force calculated in step S30 is equal to or higher than the output during idling. If it is determined that the output is equal to or greater than the output during idling, the process proceeds to step S34. In step S34, cruise control by all cylinder operation is performed.

  On the other hand, when the output is less than the output during idling, the process proceeds to step S36. In step S36, the number of cylinders to be subjected to combustion control is determined based on which region shown in FIG. 8 corresponds to the required output.

  In the subsequent step S38, the required efficiency for the output of the engine 2 is calculated. Here, the required efficiency is defined by “required output / output of efficiency 1 at the determined number of cylinders”. That is, it is defined as the ratio of the required output to the output value when the air-fuel ratio is the stoichiometric air-fuel ratio and the ignition timing is MBT with the number of cylinders determined in step S36.

  In the subsequent step S40, a lean air-fuel ratio that achieves the required efficiency is calculated. That is, in the relationship between the air-fuel ratio and torque efficiency shown in FIG. 10, the lean air-fuel ratio that is the required efficiency in step S38 is calculated.

  In the subsequent step S42, a limit value allowed as a lean air-fuel ratio is calculated based on the catalyst state. Specifically, this calculation is performed based on the oxygen storage amount of the catalyst 60 shown in FIG. That is, if the oxygen storage amount is large, the purification capacity of the catalyst 60 is reduced. Therefore, the lean air-fuel ratio value at which the oxygen storage amount increases up to the maximum storage amount that can maintain the purification capacity of the catalyst 60 is calculated as the limit value. . Incidentally, the oxygen storage amount is calculated by a known storage amount calculation method based on the detection value of the air-fuel ratio sensor 62 upstream of the catalyst 60, the detection value of the downstream oxygen sensor 64, and the like. The details of the oxygen storage amount calculation method are described in, for example, Japanese Patent Application Laid-Open No. 2005-9401 and Japanese Patent Application Laid-Open No. 8-193537.

  When the limit value is calculated in step S42, the process proceeds to step S44. In step S44, it is determined whether or not the air-fuel ratio can be leaned. If the lean operation is possible, it is determined in step S46 whether or not the required efficiency can be realized only by the lean operation. Here, it is determined that it is feasible when the lean air-fuel ratio calculated in step S40 is equal to or less than the limit value calculated in step S42, and it is determined that it cannot be realized when it is greater than the limit value.

  If it is determined in step S46 that it can be realized, the air-fuel ratio is made the lean air-fuel ratio calculated in step S40 in step S48. On the other hand, if it is determined in step S46 that it cannot be realized, a lean operation and an ignition timing retarding operation are performed in step S50. Here, first, the lean air-fuel ratio is set to the limit value calculated in step S42. The retard amount of the ignition timing is set to a retard amount that satisfies the required efficiency calculated in step S38 in cooperation with the determined lean air-fuel ratio. This is the retardation amount when the efficiency shown in FIG. 7 is “required output / (output of efficiency 1 in the determined number of cylinders) × (efficiency in determined lean air-fuel ratio)”. This can be achieved.

  On the other hand, when it is determined in step S44 that the lean operation is impossible, in step S52, the required efficiency calculated in step S38 is calculated only by the retard operation of the ignition timing. This is the ignition timing at which the efficiency shown in FIG. 7 becomes the required efficiency calculated in step S38.

  When the process in step S34 and the processes in steps S48 to S52 are completed, this series of processes is temporarily terminated.

  According to the present embodiment described above, the following effects can be obtained in addition to the effects (1) to (5) of the first embodiment.

  (7) In addition to the variable setting of the number of cylinders, a lean operation was performed. Thereby, the output which changes in steps by the variable setting of the number of cylinders can be further finely adjusted. In particular, by performing a lean operation to finely adjust the output of the engine 2, fine adjustment can be performed while reducing fuel consumption.

  (8) The variable operation amount of the air-fuel ratio and the variable operation amount of the ignition timing for generating the required output are determined according to the state of the catalyst 60. Therefore, it is possible to generate the required driving force while avoiding the air-fuel ratio that causes the exhaust characteristics to deteriorate.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the second embodiment, an ignition timing that can maximize the output of the engine 2 while suppressing knocking may be used instead of MBT.

  -In 2nd Embodiment, although the output torque of the engine 2 was finely adjusted using the lean side rather than a theoretical air fuel ratio, you may use the rich side.

  When changing the number of cylinders for which combustion control is performed, it is possible to obtain the effects (1) to (4) and (6) of the first embodiment without changing the ignition timing. it can.

  Even if the number of cylinders for which combustion control is performed is not variably set, the effects (1) to (3) and (6) of the first embodiment can be obtained.

  In the first embodiment, the above effects (1) to (5) of the first embodiment can be obtained without using ABS during cruise control.

  The control means for controlling the driving force of the vehicle based on the acceleration of the vehicle includes a driving force calculating means for calculating the driving force required for the vehicle based on the acceleration, and an operation for operating the vehicle based on the calculated driving force. It is not restricted to a thing provided with a means. For example, a map that defines the relationship between the acceleration a of the vehicle (and the gear ratio of the transmission 6 and the like) and the value of the operation parameter of the engine 2 for generating a driving force that cancels the force acting in the traveling direction of the vehicle is provided. It may be. Thereby, the calculation load of the engine control apparatus 20 can be reduced.

  A calculation means for calculating a driving force required to cause the vehicle speed to follow the target speed in cruise control, and a multi-cylinder internal combustion engine mounted on the vehicle to generate the calculated driving force; The calculation means in the cruise control device having a control means for variably setting the number of cylinders in which combustion control is performed is not limited to the calculation of the driving force based on the acceleration a of the vehicle. For example, the driving force may be calculated by PID control.

  -Engine 2 is not limited to a 4-cylinder gasoline engine. Incidentally, as the number of cylinders increases, the amount of change in output caused by variably setting the number of cylinders for which combustion control is performed can be suppressed.

  The control means for controlling the driving force of the vehicle based on the vehicle acceleration is not limited to the one that operates the engine 2 or the hydraulic actuator 12. For example, when the vehicle is a hybrid vehicle, the braking force of the vehicle may be applied by regenerative control of the electric motor.

  The detection means for detecting the acceleration of the vehicle is not limited to the one that calculates (detects) the acceleration based on the detection result of the wheel speed sensor 14. For example, the acceleration is calculated based on the force applied to itself using the piezoelectric effect or the like. The acceleration may be calculated based on the detection result of the detecting means or the like.

The figure which shows the structure of 1st Embodiment of the cruise control apparatus concerning this invention. The figure which shows the structure of the engine of the embodiment. The flowchart which shows the process sequence concerning the cruise control concerning the embodiment. The figure which shows the force added to a vehicle on a downhill. The time chart which shows the example from which acceleration differs even if the difference of a vehicle speed and target speed is the same. The figure which shows the output produced | generated by an engine. The figure which shows the relationship between the ignition timing and the efficiency of output torque. The figure which shows the aspect of the variable setting of the cylinder number concerning the said embodiment, and the variable operation of ignition timing. The time chart which shows the control aspect of the driving force of a vehicle, and transition of the vehicle speed at that time. The figure which shows the relationship between an air fuel ratio and the efficiency of an output torque. The flowchart which shows the process sequence concerning the cruise control concerning 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine (multi-cylinder internal combustion engine), 14 ... Wheel speed sensor, 12 ... Hydraulic actuator (corresponding to braking means), 20 ... Engine control device (corresponding to control means)

Claims (12)

In a cruise control device that performs cruise control that causes a vehicle to travel at a constant speed so as to follow a set target speed,
Detecting means for detecting acceleration of the vehicle;
Control means for controlling the driving force of the vehicle so as to cancel out the force acting in the traveling direction of the vehicle based on the acceleration of the vehicle detected by the detecting means during the cruise control. Cruise control device.   The said control means controls the said driving force so that the driving force of the said vehicle becomes small, so that the acceleration of the said vehicle is large, when the difference of the speed of the said vehicle and the said target speed is the same. Item 2. The cruise control device according to Item 1.   The control means includes a driving force calculation means for calculating a driving force required for the vehicle based on the detection value, and an operation means for operating the vehicle based on the calculated driving force. The cruise control device according to claim 1, wherein the driving force is controlled.   The driving force calculating means calculates the force acting in the traveling direction of the vehicle by multiplying the detected value of the acceleration by the total weight of the vehicle, and the driving force required to cancel the calculated force The cruise control apparatus according to claim 3, further comprising: a unit that calculates the required driving force based on the driving force. The vehicle includes a multi-cylinder internal combustion engine as a prime mover,
The cruise control apparatus according to claim 3 or 4, wherein the operating means variably sets the number of cylinders of the internal combustion engine on which combustion control is performed according to the required driving force.   6. The operation means performs variable operation of at least one of an air-fuel ratio and an ignition timing of the internal combustion engine in addition to the variable setting of the number of cylinders according to the required driving force. The cruise control device described. Further comprising detection means for detecting a state of a catalyst for purifying the exhaust gas of the internal combustion engine,
The operating means performs variable setting of the number of cylinders, variable operation of the air-fuel ratio, and variable operation of the ignition timing according to the required driving force, and the required driving force. 7. The cruise control apparatus according to claim 6, wherein the variable operation amount of the air-fuel ratio and the variable operation amount of the ignition timing for determining are determined in accordance with the state of the catalyst. The vehicle includes braking means for controlling the braking force of the vehicle,
The cruise control device according to claim 3 or 4, wherein the operating means operates the braking means in accordance with the calculated driving force. The vehicle includes braking means for controlling the braking force of the vehicle,
The cruise control device further includes means for distributing the driving force calculated by the driving force calculation means to the output of the prime mover and the braking force of the braking means,
The cruise control device according to any one of claims 5 to 7, wherein the operating means operates at least one of the prime mover and the braking means based on the distributed driving force. In a cruise control device that performs cruise control that causes a vehicle to travel at a constant speed so as to follow a set target speed,
A calculation means for calculating a driving force required to make the speed of the vehicle follow the target speed in the cruise control;
A cruise control device comprising a control means for variably setting the number of cylinders in which a combustion control is performed in a multi-cylinder internal combustion engine mounted on the vehicle so as to generate the calculated driving force.   The control means performs variable operation of at least one of the air-fuel ratio and the ignition timing of the internal combustion engine in addition to the variable setting of the number of cylinders in order to generate the driving force calculated by the calculation means. The cruise control device according to claim 10. Further comprising detection means for detecting a state of a catalyst for purifying the exhaust gas of the internal combustion engine,
The control means performs variable setting of the number of cylinders, variable operation of the air-fuel ratio, and variable operation of the ignition timing according to the required driving force, and the required driving force. 12. The cruise control device according to claim 11, wherein the variable operation amount of the air-fuel ratio and the variable operation amount of the ignition timing are determined in accordance with the state of the catalyst.

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