JP3678086B2 - Vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a vehicle having an internal combustion engine and a continuously variable transmission.
[0002]
[Prior art]
A CVT (Continuously Variable Transmission) used as a belt-type continuously variable transmission generally hangs a belt between a primary pulley connected to an input shaft and a secondary pulley connected to an output shaft, By supplying and discharging hydraulic pressure, the groove widths of the primary pulley and the secondary pulley are relatively changed to change the speed.
[0003]
Conventionally, in such a CVT, the controller sets a required output required by the vehicle based on the accelerator opening operated by the driver and the speed (vehicle speed) of the vehicle so that the required output is exhibited. CVT transmission ratio is set. Then, the controller controls the hydraulic pressure so as to achieve the set speed ratio, thereby relatively changing the groove widths of the primary pulley and the secondary pulley, and causing the vehicle to travel as required by the driver.
[0004]
[Problems to be solved by the invention]
By the way, in a vehicle having an engine equipped with a CVT, when the driver depresses the accelerator pedal to accelerate, the controller outputs the required output set based on the accelerator opening and the vehicle speed. Is increased, that is, set to the deceleration side.
[0005]
In such CVT shift control, for example, the driver wanted to accelerate slowly, but suddenly stepped on the accelerator pedal and felt more acceleration than expected, and then noticed that the accelerator pedal was depressed too much. The accelerator pedal may be returned. In this case, in order to obtain a high horsepower corresponding to a large accelerator opening, the engine once enters the rich operation region of low rotation and high load and then settles to the operation region of the desired horsepower by returning the accelerator pedal. Thus, there is a problem that the fuel consumption deteriorates.
[0006]
Such a phenomenon will be described in detail. FIG. 5 shows a graph representing an operation state by a conventional control device in a vehicle having an engine and a CVT. As shown in FIG. 5, when the driver suddenly depresses the accelerator pedal too much from the acceleration start position {1} of low engine speed and low load of the engine, the engine operating state becomes the target average based on the accelerator opening and the vehicle speed. The effective pressure, that is, the engine load (output) Pe is set, and the process proceeds to the acceleration initial position {circle around (2)} at a high load on the horsepower A curve. Then, as the engine speed Ne increases, the gear ratio is reduced to move to the acceleration middle position (3) on the horsepower B curve, and move on the horsepower B curve to move to the acceleration end position (4). Thereafter, when the driver returns the accelerator pedal, the engine speed Ne and the engine load Pe decrease and move to a desired acceleration position (5) on a desired horsepower A curve. When the engine operating state changes as described above, the vehicle speed is substantially constant, the engine speed Ne and the engine load Pe increase, and the engine enters the enriched zone in the middle of acceleration, resulting in deterioration of fuel consumption.
[0007]
Note that, for example, disclosed in Japanese Examined Patent Publication No. 3-35536 is a technique that can sufficiently obtain acceleration during a transition after an acceleration operation, but this technique is effective at the time of kickdown. However, there is a problem that a sufficient output cannot be obtained at the time of slow acceleration, and further, a sense of acceleration cannot be obtained due to the inertia torque of CVT.
[0008]
The present invention solves such a problem. By appropriately detecting the slow acceleration of the vehicle and setting a target output that does not become an enriched zone, the fuel efficiency is improved and the acceleration failure is prevented to improve drivability. An object of the present invention is to provide a control device for a vehicle with improved performance.
[0009]
[Means for Solving the Problems]
In order to achieve the above-described object, the vehicle control apparatus according to the first aspect of the invention responds to the operating condition when the slow acceleration of the vehicle is detected and the target air-fuel ratio at this time is on the concentration side of the stoichiometric air-fuel ratio. The target horsepower is calculated, the target output and the target rotational speed for obtaining this target horsepower near the theoretical air-fuel ratio are set, and the speed ratio of the continuously variable transmission and the target rotational speed are set so as to be the set target output and target rotational speed. The output of the internal combustion engine is controlled.
[0010]
Therefore, when the vehicle's slow acceleration and the concentrated air-fuel ratio are detected, the target output and target rotational speed for obtaining the target horsepower in the vicinity of the theoretical air-fuel ratio are set, so that the operating state of the internal combustion engine becomes an enriched zone. However, the deterioration of fuel consumption due to the driver's inadvertent acceleration due to excessive depression of the accelerator pedal is prevented.
[0011]
In the vehicle control device according to the second aspect of the present invention, the actual rotational speed of the input shaft of the continuously variable transmission is detected, and the target output is corrected based on the target rotational speed and the actual rotational speed. The output of the internal combustion engine is controlled based on the target output. Therefore, since the output of the internal combustion engine is controlled using the actual rotational speed of the input shaft of the continuously variable transmission, it is possible to prevent acceleration failure and improve drivability.
Further, in the vehicle control apparatus according to the third aspect of the invention, the second target air-fuel ratio is obtained from the corrected target output and the actual rotational speed, and the second target air-fuel ratio is on the more concentrated side than the theoretical air-fuel ratio. In this case, a new target output is obtained from the theoretical air-fuel ratio and the actual rotational speed, and the output of the internal combustion engine is controlled based on the target output. Therefore, since the output of the internal combustion engine is controlled using the actual rotational speed of the input shaft of the continuously variable transmission, it is possible to prevent entry into the enriched region and prevent deterioration of fuel consumption.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a schematic configuration of a vehicle control device according to an embodiment of the present invention, FIG. 2 is a flowchart of CVT output control by the vehicle control device of the present embodiment, and FIG. A graph showing the engine load, and FIG. 4 shows a graph showing a correction coefficient for the primary rotational speed deviation.
[0014]
In the vehicle control apparatus of the present embodiment, as shown in FIG. 1, the drive shaft 12 of the engine 11 is connected to a torque converter 13, and the output shaft 14 of the torque converter 13 is connected to a continuously variable transmission via a transmission clutch 15. The CVT 16 can be connected to and disconnected from an input shaft (primary shaft) 17, and the transmission clutch 15 can be driven by an actuator 18 that is operated by a hydraulic drive device (not shown). This CVT 16 includes a primary pulley 19 connected to the engine 11 side, a secondary pulley 20 connected to the vehicle shaft side, a belt 21 and the like spanned between both pulleys 19, 20. The inputted rotation is inputted from the coaxial integrated primary pulley 19 to the secondary pulley 20 via the belt 21 and outputted to the secondary shaft 22.
[0015]
That is, the primary pulley 19 has a fixed sheave 19a and a movable sheave 19b, and a primary cylinder 19c is formed on the back side of the movable sheave 19b. Accordingly, by supplying and discharging hydraulic pressure to and from the primary cylinder 19c, the movable sheave 19b can be moved relative to the fixed sheave 19a, and the groove width of the pulley can be made variable. Similarly, the secondary pulley 20 has a fixed sheave 20a and a movable sheave 20b, and a secondary cylinder 20c is formed on the back side of the movable sheave 20b. Therefore, by supplying and discharging hydraulic pressure to and from the secondary cylinder 20c, the movable sheave 20b can be moved relative to the fixed sheave 20a, and the groove width of the pulley can be made variable.
[0016]
The CVT 16 is controlled by a hydraulic circuit. That is, the secondary hydraulic pressure (line pressure) regulated by the regulator valve 23 is applied to the secondary cylinder 20c, and the primary hydraulic pressure regulated by the transmission ratio control valve 24 is applied to the primary cylinder 19c. In addition, 25 is an oil pan, 26 is an oil pump which supplies the oil in the oil pan 25 to the regulator valve 23 side.
[0017]
The secondary shaft 22 of the CVT 16 is connected to a differential gear 28 via a start clutch 27. The start clutch 27 can be driven by an actuator 29 that is operated by a hydraulic drive device (not shown). The amount of torque transmitted to the left and right drive wheels 30 can be adjusted.
[0018]
Further, the vehicle is provided with an engine electronic control unit (ECU) 31 for controlling the engine 11, the CVT 16, and the like. The ECU 31 includes an input / output device, a storage device for storing a control program, a control map, and the like, and a central processing unit. A device, a timer, and counters are provided, and the ECU 31 performs comprehensive control of the engine 11. That is, detection information of various sensors such as an engine speed sensor (crank angle sensor) 32, a vehicle speed sensor 33, an accelerator pedal position sensor 34, and a primary speed sensor 35 is input to the ECU 31, and the ECU 31 detects the various sensors. Based on the information, a fuel injection mode, a fuel injection amount, an ignition timing, and the like are determined. Further, the ECU 31 can change the pulley ratio and change the gear ratio by controlling the hydraulic pressure of the regulator valve 23 and the gear ratio control valve 24 of the CVT 16. The ECU 31 also controls the actuators 18 and 29 of the transmission clutch 15 and the start clutch 27.
[0019]
By the way, in the vehicle control apparatus of the present embodiment, the ECU 31 detects the slow acceleration and the rich region acceleration of the vehicle (slow acceleration and the rich region acceleration detecting means), and the slow acceleration and the rich region acceleration of the vehicle are detected. The target horsepower is calculated according to the driving state at that time (target horsepower calculating means), the target output and target rotational speed for obtaining this target horsepower near the theoretical air-fuel ratio are set (target value setting means), The gear ratio of the CVT 16 and the output of the engine 11 are controlled (control means) so that the set target output and target rotational speed are obtained. Specifically, the actual rotational speed of the input shaft (primary shaft 17) of the CVT 16 is detected (rotational speed detecting means), and the target output is corrected based on the target rotational speed and the actual rotational speed detected by the rotational speed detecting means. (Target output correcting means), and the output of the engine 11 is controlled based on the corrected target output.
[0020]
Here, the control of the ECU 31 in the vehicle control apparatus of the present embodiment described above will be described in detail based on the flowchart of FIG. 2 and the graph showing the change of the driving state at the time of the slow acceleration and the rich region acceleration of the vehicle in FIG. .
[0021]
As shown in FIG. 2, first, in step S1, the accelerator opening APS detected by the accelerator position sensor 34 and the engine speed Ne detected by the engine speed sensor 32 are read. In step S2, it is detected whether or not the accelerator opening APS is smaller than the predetermined accelerator opening APS _S and the target air-fuel ratio KAF is smaller than 14.7. Determine. In this case, the target air-fuel ratio KAF is obtained from the engine speed and the engine load Pe. If the accelerator opening APS is equal to or greater than the predetermined accelerator opening APS _S or the target air-fuel ratio KAF is equal to or greater than 14.7, it is determined that the vehicle is rapidly accelerating or is in steady operation, and the process proceeds to step S13. Thus, the engine 11 and the CVT 16 are output as usual.
[0022]
On the other hand, in step S2, if the accelerator opening APS is smaller than the predetermined accelerator opening APS _S and the target air-fuel ratio KAF is smaller than 14.7, it is determined whether the vehicle is slowly accelerating or enriched. The process proceeds to S3. In step S3, the target Pe ₁ is a target average effective pressure of the engine 11 according to the operating state at this time, reads the target Np ₁ is a target primary rotation speed of CVT16, to the target Pe ₁ and the target Np ₁ Based on this, the target horsepower PS is calculated. In this case, in the graph of FIG. 3, when the driver suddenly steps on the accelerator pedal from the acceleration start position {circle around (1)} of the engine 11 at a low rotation, the target Pe of the engine 11 becomes the high load on the horsepower A curve. It will be an enriched zone. Therefore, in step S4, in order to obtain the target horsepower PS in stoichiometric feedback S-F / B region (near the stoichiometric air-fuel ratio), the target Pe ₁ and the target Pe ₂ and the target Np ₂ on the target Np ₁ horsepower A curve Change to (acceleration position (3)).
[0023]
However, even if the ECU 31 sets the target Pe ₂ and the target Np ₂ , a shift delay occurs in the CVT 16, so that a delay in the rotation of the primary shaft 17 of the CVT 16 is delayed due to the shift delay of the CVT 16. Therefore, during this period, the target Pe ₂ is corrected so as to suppress a decrease in horsepower that occurs due to a delay in the rotation of the primary shaft 17. That is, in step S5, read the actual rotational speed Np _r of the primary shaft 17 of CVT16 the primary speed sensor 35 detects, in step S6, calculates the deviation ΔNp between the actual rotational speed Np _r and the target Np ₂ . In step S7, the Pe correction coefficient K _Pe is obtained from the correction coefficient map shown in FIG. 4 based on the deviation ΔNp, and in step S8, the target Np ₂ is multiplied by the Pe correction coefficient K _Pe, thereby correcting the correction target Pe. to calculate the _a. Thus the obtained correction target Pe _a position between the actual rotation speed Np _r is an acceleration relay position ▲ 2 is ▼ representing in FIG. This prevents the acceleration failure caused by the shift delay of the CVT 16.
[0024]
Then, in step S9, seek the corrected target Pe _a and the actual rotation speed Np _r from the target air-fuel ratio KAF _T (second target air-fuel ratio), at step S10, the target air-fuel ratio KAF _T obtained 14.7 It is determined whether or not it is smaller, that is, whether or not the acceleration relay position (2) shown in FIG. 3 is in the enriched zone. In step S10, if the target air-fuel ratio KAF _T is smaller than 14.7 and the acceleration relay position (2) is in the enriched zone, in step S11, the target air-fuel ratio KAF is set to 14.7 and actual rotation is performed. by the number Np _r to set the target Pe. As a result, although the horsepower is reduced, the acceleration feeling is slightly deteriorated, but the entry into the enriched region is prevented, and the deterioration of fuel consumption can be prevented. On the other hand, if the target air-fuel ratio KAF _T is 14.7 or more and the acceleration relay position (2) is in the SF / B zone in step S10, the target air-fuel ratio KAF is set to the corrected target Pe _a in step S12. and sets the target air-fuel ratio KAF _T determined from the rotational speed Np _r, sets the target Pe _a target Pe. Then, the output of the engine 11 is controlled based on the set target air-fuel ratio KAF and target Pe.
[0025]
Therefore, during the shift of the CVT 16 during the slow acceleration and the enrichment region acceleration of the vehicle, the acceleration start position (1) is shifted to the acceleration position (3) through the acceleration relay position (2) in the SF / B zone. . Then, from this acceleration position {circle over (3)}, the engine speed Ne (primary speed Np) and the engine load Pe rise and shift to the horsepower B curve.
[0026]
As described above, in the vehicle control apparatus of the present embodiment, when the slow acceleration and the enrichment range acceleration of the vehicle are detected, the target Pe ₂ and CVT 16 of the engine 11 for obtaining the target horsepower PS in the vicinity of the theoretical air-fuel ratio. The target Np ₂ is set so that the operating state of the engine 11 does not become an enriched zone, and deterioration of fuel consumption due to inadvertent acceleration of the driver due to excessive depression of the accelerator pedal is prevented. In this case, to detect the actual rotational speed Np _r of the primary shaft 17 of CVT16, seeking Pe correction coefficient K _Pe based on the deviation ΔNp between the actual rotational speed Np _r and the target Np _2, the Pe correction coefficient K _Pe Thus, the target Np ₂ is corrected to prevent acceleration failure and improve drivability.
[0027]
In the above-described embodiment, the slow acceleration of the vehicle is determined based on the accelerator opening APS. However, the accelerator opening change rate may be used instead of the accelerator opening APS, and the throttle opening may be used. Also good. Furthermore, although the target air-fuel ratio KAF _T had an upper limit value such that the near stoichiometric, in the case where poor acceleration is considered greater may delete the upper limit setting. Furthermore, in the above embodiment, the target Np or the like may be set so as to be SF / B. In particular, the feedback control may not be necessary. It may be a lean air-fuel ratio. In the above-described embodiment, the belt type CVT 16 is used as the continuously variable transmission. However, other types of continuously variable transmissions such as a toroidal CVT may be used.
[0028]
【The invention's effect】
As described above in detail in the embodiment, according to the vehicle control apparatus of the first aspect of the present invention, the target horsepower calculated according to the driving state at the time of slow acceleration and rich region acceleration of the vehicle is set in the vicinity of the theoretical air-fuel ratio. The target output and the target rotational speed to be obtained in the above are set, and the gear ratio of the continuously variable transmission and the output of the internal combustion engine are controlled so as to be the set target output and target rotational speed. The driving state does not become an enriched zone, and it is possible to prevent deterioration of fuel consumption due to driver's inadvertent acceleration due to excessive depression of the accelerator pedal.
[0029]
According to the vehicle control device of the second aspect of the invention, the actual rotational speed of the input shaft of the continuously variable transmission is detected, the target output is corrected based on the target rotational speed and the actual rotational speed, and the correction is performed. Since the output of the internal combustion engine is controlled based on the target output thus made, it is possible to prevent acceleration failure and improve drivability.
Furthermore, according to the vehicle control apparatus of the third aspect of the invention, the second target air-fuel ratio is obtained from the corrected target output and the actual rotational speed, and the second target air-fuel ratio is more concentrated than the stoichiometric air-fuel ratio. In this case, since the target output is newly obtained from the theoretical air-fuel ratio and the actual rotational speed, and the output of the internal combustion engine is controlled based on the target output, the actual rotational speed of the input shaft of the continuously variable transmission is Since the output of the internal combustion engine is controlled by using this, it is possible to prevent the engine from entering the rich region and to prevent deterioration of fuel consumption.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a vehicle control apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart of CVT output control by the vehicle control apparatus of the present embodiment.
FIG. 3 is a graph showing a primary rotational speed and an engine load at the time of slow acceleration of the vehicle.
FIG. 4 is a graph showing a correction coefficient for a primary rotational speed deviation.
FIG. 5 is a graph showing a driving state by a conventional control device in a vehicle having an engine and a CVT.
[Explanation of symbols]
11 Engine (Internal combustion engine)
16 CVT (type continuously variable transmission)
17 Primary shaft 23 Regulator valve 24 Gear ratio control valve 31 Electronic circuit unit for engine, ECU (target horsepower calculation means, target value setting means, control means, target output correction means)
32 Engine speed sensor 33 Vehicle speed sensor 34 Accelerator position sensor 35 Primary speed sensor (rotation speed detecting means)

Claims (3)

In a control device for a vehicle having an internal combustion engine and a continuously variable transmission,
Slow acceleration detecting means for detecting slow acceleration of the vehicle;
Target air-fuel ratio setting means for setting a target air-fuel ratio at the time of slow acceleration;
The target horsepower is calculated according to the operating state when the slow acceleration of the vehicle is detected by the slow acceleration detection means and the target air fuel ratio set by the target air fuel ratio setting means is on the richer side than the theoretical air fuel ratio. A target horsepower calculating means;
Target value setting means for setting a target output and target rotational speed for obtaining the target horsepower calculated by the target horsepower calculation means in the vicinity of the theoretical air-fuel ratio;
Control of a vehicle characterized by comprising control means for controlling the transmission ratio of the continuously variable transmission and the output of the internal combustion engine so that the target output and target rotational speed set by the target value setting means are obtained. apparatus. The vehicle control device according to claim 1,
A rotational speed detecting means for detecting an actual rotational speed of the input shaft of the continuously variable transmission;
Target output correction means for correcting the target output based on the target rotation speed and the actual rotation speed detected by the rotation speed detection means;
The vehicle control apparatus, wherein the control means controls the output of the internal combustion engine based on the target output corrected by the target output correction means. The vehicle control device according to claim 2,
The control means obtains a second target air-fuel ratio from the corrected target output and the actual rotational speed, and when the second target air-fuel ratio is on the more concentrated side than the stoichiometric air-fuel ratio, A vehicle control apparatus characterized by newly obtaining a target output from the actual rotational speed and controlling the output of the internal combustion engine based on the target output.

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