JP4195741B2 - Vehicle running control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle in which the output of an engine is shifted using an automatic transmission (particularly, an automatic transmission having a continuously variable transmission mechanism, etc.) and transmitted to drive wheels for driving. The present invention relates to a method for estimating a traveling road surface gradient of a vehicle and performing vehicle traveling control using the estimated gradient.
[0002]
[Prior art]
Shift control of an automatic transmission, particularly an automatic transmission having a continuously variable transmission mechanism, obtains an engine torque based on the intake negative pressure of the engine and the engine rotational speed, and obtains a running state from the engine torque and the vehicle speed. Generally, the gear ratio is set so that a target engine speed corresponding to an index (for example, engine throttle opening degree, accelerator pedal depression amount, etc.) indicating the driver's acceleration will be obtained under driving conditions. Is. As a continuously variable transmission, a transmission using a metal V-belt is well known. However, in this continuously variable transmission, one pulley side pressure in the driving and driven pulleys is reduced to such an extent that no belt slip occurs. Control is generally performed to set and set the other pulley side pressure so as to obtain a desired gear ratio. An example of such control is a control device disclosed in Japanese Patent Application Laid-Open No. 60-256661, and this control device is characterized by shift control particularly during lean burn operation of the engine.
[0003]
[Problems to be solved by the invention]
As described above, in the shift control of an automatic transmission, particularly a continuously variable transmission, it is necessary to accurately determine the engine output, that is, the engine torque and the rotation. If the engine torque is calculated, there is a problem that the calculation accuracy is not so good. For example, when a lean burn (lean combustion) operation is performed for the purpose of improving the fuel consumption of the engine, the engine torque calculated based on the intake negative pressure and the engine rotation becomes larger than the actual engine torque.
[0004]
If the pulley side pressure control and the shift control are performed based on such an inaccurate calculated engine torque, there is a problem that the fuel consumption deteriorates. In addition, when the vehicle is traveling on a gradient road surface, it is necessary to perform shift control and the like in consideration of the traveling resistance associated with the gradient, but in general, gradient estimation is often performed by calculating engine torque. As described above, when the calculated engine torque is inaccurate, accurate gradient estimation control cannot be performed, and there is a problem that driving performance (drivability) deteriorates.
[0005]
Note that the shift control in consideration of the traveling resistance associated with the gradient is supported by setting a different shift map for each gradient and performing the shift control using the shift map corresponding to the actual traveling road surface gradient. When such shift control is used, in an automatic transmission (gear-type stepped transmission), the shift stage is set according to the vehicle speed and the throttle opening. As long as the gear position is not changed, the engine speed does not fluctuate if the vehicle speed and the throttle opening are the same.
[0006]
However, since the continuously variable transmission uses a shift map in which the target engine speed corresponding to the vehicle speed and the throttle opening is set, if the shift map is changed, the target engine speed corresponding to the vehicle speed and the throttle changes. Even if the vehicle speed and the throttle opening are the same, the shift control is performed and the target engine speed changes. For this reason, for example, when the traveling road surface gradient changes greatly on the uphill road side during traveling, the shift map is changed in response to this gradient change, and the target engine speed is high even if the vehicle speed and accelerator opening are not changed. Thus, the shift control is performed to increase the engine rotation. For this reason, if the gradient estimation is inaccurate as described above, there is a problem that the engine rotation may be unnecessarily high and the fuel consumption may be deteriorated. In particular, during lean burn operation, it is required to drive at a low engine speed at a high throttle opening, but if the gradient estimation is inaccurate, the engine rotation will increase at a high throttle opening and the gradient estimation will not be performed. In contrast, there is a risk that the fuel consumption may be reduced.
[0007]
The present invention has been made in view of such a problem, and provides a method for accurately estimating the traveling road surface gradient of the vehicle and performing appropriate vehicle traveling control (shift control) based on the estimated road surface gradient. The purpose is to do.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, in the traveling control method according to the present invention, in a vehicle configured to travel by shifting the output of the engine by the automatic transmission and transmitting it to the drive wheels, first, the fuel consumption of the engine calculating a, a step of the fuel consumption calculated Ru determined output torque of the engine, the detection gear ratio and drive torque of the drive wheels on the basis of the engine output torque detects a gear ratio of the automatic transmission a step Ru determined, the steps asking you to road gradient on which the vehicle is traveling based on the traveling speed and the driving torque of the vehicle, an index indicating the acceleration intention of the driver (for example, an engine throttle opening, the accelerator pedal depression amount and the like ) and step and the rotational speed of the engine target engine to set the target engine rotational speed based on the road surface gradient obtained in this manner Composed of a step of performing a shift control of the automatic transmission so that the rotational speed. And the step of detecting the fuel consumption of the engine calculates the fuel amount required for each engine cylinder based on an index indicating the driver's acceleration intention, and calculates the fuel amount, the engine cooling water temperature, The ratio of the amount of fuel supplied directly to the engine cylinder when the fuel is injected by the injector is configured to calculate the required fuel amount of the engine by correcting based on the intake air temperature and the atmospheric pressure. The fuel injection amount injected from the injector is corrected by correcting the required fuel amount of the engine based on the ratio of adhering to the wall surface without being inhaled and the ratio of the fuel adhering to the wall surface supplied to the engine cylinder at the next inhalation. It is configured to calculate and inject this fuel injection amount from the injector to perform engine drive control. Based on this fuel injection amount calculates the basic torque of the engine, is configured to determine the output torque of the engine by correcting the accessory drive loss from the basic torque.
Note that it is preferable to apply this travel control method to a vehicle equipped with an automatic transmission including a continuously variable transmission.
[0009]
In such a method according to the present invention, the fuel injection amount injected from the injector is calculated from the required fuel consumption amount of the engine , and the engine output torque is calculated from this fuel injection amount. For example, it is always possible to accurately determine the actual engine output torque regardless of whether it is normal combustion or lean combustion. With such an accurate engine output, the vehicle road surface gradient can also be accurately determined. It is possible to estimate. Furthermore, using the travel road surface gradient accurately estimated in this way makes it possible to perform optimal shift control and to ensure good driving characteristics (drivability).
[0010]
In particular, when the shift control of the continuously variable transmission is performed using a different shift map for each traveling road surface gradient, the optimum shift map can always be selected based on accurate gradient estimation, and the engine speed can be reduced. There is no risk of excessively high fuel consumption.
[0011]
In addition, since the engine output torque can be calculated accurately based on the fuel consumption of the engine, the engine output torque can be compared with the conventional method of estimating the engine output torque from the engine intake negative pressure and the engine rotation. There is also an advantage that the arithmetic processing program is simplified.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2 show the configuration of a belt-type continuously variable transmission in which shift control is performed by the shift control method according to the present invention. This belt-type continuously variable transmission CVT includes a metal V-belt mechanism 10 disposed between the input shaft 1 and the counter shaft 2, and a planet disposed between the input shaft 1 and the drive-side movable pulley 11. It comprises a gear type forward / reverse switching mechanism 20 and a main clutch 5 disposed between the counter shaft 2 and an output member (differential mechanism 8 or the like). The continuously variable transmission CVT is used for a vehicle. The input shaft 1 is connected to the output shaft of the engine ENG via a coupling mechanism CP, and the power transmitted to the differential mechanism 8 is transmitted to the left and right drive wheels. The
[0013]
The metal V belt mechanism 10 includes a driving pulley 11 disposed on the input shaft 1, a driven pulley 16 disposed on the counter shaft 2, and a metal V wound between the pulleys 11 and 16. Belt 15.
[0014]
The drive pulley 11 includes a fixed pulley half 12 that is rotatably disposed on the input shaft 1 and a movable pulley half 13 that can move relative to the fixed pulley half 12 in the axial direction. On the side of the movable pulley half 13, a drive side cylinder chamber 14 is formed surrounded by a cylinder wall 12 a coupled to the fixed pulley half 12, and the hydraulic pressure Pdr supplied into the drive side cylinder chamber 14 is formed. Thus, a side pressure for moving the movable pulley half 13 in the axial direction, that is, an axial thrust Qdr of the driving pulley is generated.
[0015]
The driven pulley 16 includes a fixed pulley half 17 fixed to the counter shaft 2 and a movable pulley half 18 that can move relative to the fixed pulley half 17 in the axial direction. On the side of the movable pulley half 18, a driven side cylinder chamber 19 is formed surrounded by a cylinder wall 17 a coupled to the fixed pulley half 17, and the hydraulic pressure Pdn supplied into the driven side cylinder chamber 19 is formed. Thus, a side pressure for moving the movable pulley half 18 in the axial direction, that is, an axial thrust Qdn of the driven pulley is generated.
[0016]
Therefore, by appropriately controlling the hydraulic pressures Pdr and Pdn supplied to both the cylinder chambers 14 and 19, an appropriate pulley side pressure that does not cause the belt 15 to slip is set, and the pulley widths of the pulleys 11 and 16 are set. Thus, the winding ratio of the V-belt 15 can be changed to change the speed ratio i steplessly.
[0017]
The planetary gear type forward / reverse switching mechanism 20 has a double pinion type planetary gear train, its sun gear 21 is coupled to the input shaft 1, the carrier 22 is coupled to the stationary pulley half 12, and the ring gear 23 is fixed by the reverse brake 27. It can be held. Further, the forward clutch 25 capable of connecting the sun gear 21 and the ring gear 23 is provided. When the forward clutch 25 is engaged, all the gears 21, 22 and 23 rotate integrally with the input shaft 1, and the driving pulley 11 Are driven in the same direction (forward direction) as the input shaft 1. On the other hand, when the reverse brake 27 is engaged, the ring gear 23 is fixedly held, so the carrier 22 is driven in the opposite direction to the sun gear 21 and the drive pulley 11 is in the opposite direction (reverse direction) to the input shaft 1. ).
[0018]
The main clutch 5 is a clutch for controlling the power transmission between the counter shaft 2 and the output side member. During the engagement, the power transmission between the two is possible, and the engagement force is controlled to control the input side. The torque transmission capacity (torque capacity) with the output side can also be controlled. Therefore, when the main clutch 5 is engaged, the engine output changed by the metal V-belt mechanism 10 is transmitted to the differential mechanism 8 via the gears 6a, 6b, 7a, 7b, and the left and right wheels are transmitted by the differential mechanism 8. It is divided and transmitted (not shown). When the main clutch 5 is released, this power transmission cannot be performed, and the transmission is in a neutral state.
[0019]
The speed change control device controls the supply hydraulic pressures Pdr and Pdn of the drive side and driven side cylinder chambers 14 and 19 to control the axial thrusts Qdr and Qdn of the drive side and driven side pulleys, and the minimum necessary without causing belt slip. An appropriate shift control is performed while setting a limited axial thrust, and the method according to the present invention is used for the control, and the contents thereof will be described in detail below.
[0020]
This shift control detects various operating conditions and is performed based on the detected operating conditions. The contents of this control are shown in FIG. In this shift control, first, the engine output torque ETQNT is calculated (step S1). This calculation method is shown in FIG. Here, the fuel injection amount Tout of the engine is first calculated (step S11). This calculation is performed by taking the following steps. First, the amount of fuel required for each engine cylinder is determined based on the amount of depression of the accelerator pedal by the driver or the engine throttle opening (an index indicating the driver's acceleration intention). However, at this time, the required fuel amount varies depending on the combustion state of the engine (operation in normal combustion or lean combustion), engine cooling water temperature, intake air temperature, atmospheric pressure, etc. The required fuel amount is calculated by performing the correction. The ratio of the required fuel amount calculated in this way to the cylinder directly in the fuel injected from the injector, the ratio of the fuel adhering to the wall surface, the ratio of the fuel adhering to the wall surface supplied to the cylinder at the next intake Based on the above, the fuel injection amount Tout is calculated by performing various corrections.
[0021]
Here, the engine basic torque ETQGR output with respect to the fuel injection amount Tout of the engine is uniquely determined with respect to the fuel injection amount Tout as shown in FIG. For this reason, if the fuel injection amount Tout of the engine can be calculated as described above, the engine basic torque ETQGR is obtained from the relationship of FIG. 5 (step S12). However, this engine basic torque ETQGR does not include mechanical loss inside the engine or auxiliary machine drive loss such as alternator and air conditioner. Engine output torque ETQNT (net torque) obtained from the shaft is calculated (step S13).
[0022]
As described above, when the engine output torque ETQNT is obtained in step S1, the process proceeds to step S2, and the wheel driving force FWL obtained by transmitting the engine output torque ETQNT to the wheels is calculated. FIG. 6 shows this calculation method. First, correction is performed to remove the oil pump driving load for obtaining the hydraulic pressure used for transmission operation control from the engine output torque ETQNT (step S21). Since the corrected torque is transmitted to the wheels via the continuously variable transmission CVT, the final reduction gear 8, the drive shaft, etc., first, correction based on the transmission efficiency in these power transmission systems is performed (step S22). Then, the transmission ratio i of the continuously variable transmission CVT is detected, converted using the transmission ratio i and the reduction ratio of the final reduction gear, that is, the reduction ratio (ratio) of the power transmission system, and the driving torque of the drive wheels is converted. Further, the driving force FWL of the driving wheel is calculated based on the diameter of the driving wheel (step S23).
[0023]
Next, the road gradient on which the vehicle is currently traveling is estimated based on the driving force FWL of the driving wheel calculated in this way (step S3). This estimation method is shown in FIG. 7. First, the running resistance RVH of the vehicle is calculated (step S31). The running resistance RVH can be calculated as the sum of the wheel rolling resistance RRD, the air resistance RAR, the acceleration resistance RAC, and the inertia resistance RIN. The rolling resistance RRD and the air resistance RAR correspond to the vehicle speed, and can be obtained by detecting the vehicle speed V. On the other hand, the acceleration resistance RAC and the inertia resistance RIN are the vehicle-side resistance and the inertial resistance of the power transmission system that are generated when the vehicle is accelerated, respectively, and the actual acceleration GAC of the vehicle (that is, the rate of change of the vehicle speed V). Can be detected.
[0024]
When the driving force FWL and the running resistance RVH are obtained as described above, the difference between the two (FWL-RVH) acts as a force for accelerating the vehicle, so the theory when the vehicle is running on a flat road is assumed. The acceleration GTH can be calculated (step S32). Then, by comparing the theoretical acceleration GTH with the actual acceleration GAC, the road surface gradient SLRD in which the current vehicle is traveling can be calculated (step S33).
[0025]
On the other hand, a plurality of target engine speed maps for shift control are prepared in advance in the control system according to the gradient. One of such a plurality of maps is shown in FIG. 9. As can be seen from this figure, a graph showing the vehicle speed V on the horizontal axis and the target engine speed Neo on the vertical axis shows the engine throttle opening θTH. The line which shows a desired target engine speed for every is shown. Therefore, if the current vehicle speed V and the current engine throttle opening degree θTH are detected, the target engine speed Neo corresponding to this can be obtained. Note that FIG. 9 is a map for obtaining a desired target engine speed when the road surface gradient is light, and in this system, in addition to this, a medium uphill road, a heavy uphill road, Each of the light downhill road, the light downhill road, and the heavy downhill road has a map in which a desired target engine speed is set according to the road surface gradient.
[0026]
Therefore, when the road surface gradient SLRD is estimated in step S3, the target engine speed Neo is searched using this map (step S4). This content is shown in FIG. 8. First, a map corresponding to the road surface gradient SLRD estimated in step S3 is selected (step S41), and the current engine throttle opening θTH and vehicle speed V are detected (step S42). Then, the target engine speed Neo corresponding to the engine throttle opening θTH and the vehicle speed V is read from the selected map (step S43).
[0027]
When the target engine speed Neo is obtained in this way, the shift control of the continuously variable transmission CVT is performed so that the current engine speed Nea matches the target engine speed Neo. Specifically, this shift control is performed by controlling the supply hydraulic pressures (pulley side pressures) Pdr and Pdn of the drive side and driven side cylinder chambers 14 and 19 of the continuously variable transmission CVT (step S5). The details of this pulley side pressure control are shown in FIG. 10. First, from the engine output torque ETQNT calculated in step S1 and the gear ratio i of the continuously variable transmission, the engine output torque ETQNT is smooth without slipping of the belt. The pulley-required side pressure Pnec required for transmission to the vehicle is calculated (step S51). Further, a shift pulley side pressure Psht necessary for performing shift control for obtaining the target engine speed Neo is calculated (step S52). This speed change pulley side pressure Psht is set with respect to the pulley required side pressure Pnec, and this determines the speed change speed.
[0028]
When the pulley required side pressure Pnec and the speed change pulley side pressure Psht are obtained in this way, the pulley side pressure in the drive side and driven side cylinder chambers 14 and 19 is set to the side pressure thus obtained in consideration of the speed change direction. In addition, pulley side pressure control is performed by a hydraulic valve. As a result, a desired shift is performed.
[0029]
In the above description, the case where the metal V-belt type continuously variable transmission is used has been described. However, the present invention is not limited to the type of continuously variable transmission, and further, an automatic transmission having multiple speeds. It is also possible to apply to a machine.
[0030]
【The invention's effect】
As described above, according to the present invention, since the engine output torque is calculated from the fuel consumption of the engine, it is always actual regardless of the combustion state (for example, normal combustion or lean combustion). The engine output torque of the vehicle can be accurately obtained, and the road surface gradient of the vehicle can be accurately estimated using such an accurate engine output. If the travel road surface gradient accurately estimated in this way is used, optimum shift control of the automatic transmission is possible, and good driving characteristics (drivability) can be ensured. When shifting control of a continuously variable transmission is performed using a different shift map for each traveling road surface gradient, an optimal shift map can always be selected based on accurate gradient estimation, and the engine speed can be reduced. There is no risk of excessively high fuel consumption. In addition, since the engine output torque can be calculated accurately based on the fuel consumption of the engine, the engine output torque can be compared with the conventional method of estimating the engine output torque from the engine intake negative pressure and the engine rotation. The arithmetic processing program is simplified.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a continuously variable transmission to which the present invention is applied.
FIG. 2 is a schematic diagram showing a power transmission system of the continuously variable transmission.
FIG. 3 is a flowchart showing details of shift control of the continuously variable transmission.
FIG. 4 is a flowchart showing calculation details of engine output torque in this shift control.
FIG. 5 is a graph showing the relationship between engine fuel injection amount and engine output torque.
FIG. 6 is a flowchart showing a driving force calculation content in the shift control.
FIG. 7 is a flowchart showing details of road surface slope estimation in the shift control.
FIG. 8 is a flowchart showing a map search content of a target engine speed in this shift control.
FIG. 9 is a graph showing a relationship among a target engine speed, a vehicle speed, and an engine throttle opening.
FIG. 10 is a flowchart showing details of pulley side pressure control in the shift control.
[Explanation of symbols]
CVT continuously variable transmission ENG engine

Claims (1)

In a vehicle that travels by shifting the output of the engine with an automatic transmission and transmitting it to the drive wheels
Calculating fuel consumption of the engine ;
A step from the calculated fuel consumption Ru determined output torque of the engine,
A step of said detecting a gear ratio of the automatic transmission, Ru obtains a driving torque of the driving wheel based on the output torque of the engine and the detected transmission gear ratio,
A step of said detecting a running speed of the vehicle, Ru seek road gradient on which the vehicle is traveling on the basis of said driving torque and the detected travel speed,
Setting a target engine speed based on an index indicating the driver's acceleration intention and the road gradient ;
And a step of performing shift control of the automatic transmission so that the rotational speed of the engine becomes the target engine rotational speed ,
Detecting the fuel consumption of the engine,
The fuel amount required for each engine cylinder is calculated based on an index indicating the driver's acceleration intention, and this is corrected based on the combustion state of the engine, the engine coolant temperature, the intake air temperature, and the atmospheric pressure, and Configured to determine the required fuel quantity of the engine,
Determining the engine output torque,
Based on the ratio supplied directly to the engine cylinder when fuel is injected by the injector, the ratio that adheres to the wall surface without being inhaled, and the ratio that is supplied to the engine cylinder at the next inhalation in the wall surface attached fuel The fuel injection amount that is injected from the injector is calculated by correcting the required fuel amount of the engine, the fuel injection amount is injected from the injector, and the engine drive control is performed. A vehicle travel control method comprising: calculating a basic torque of the engine based on a quantity; and correcting an auxiliary drive loss from the basic torque to obtain an output torque of the engine .

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