JP2006138265A - Torque control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque control device for a vehicle capable of providing good initial responsiveness while materializing smooth acceleration performance and satisfying exhaust emission regulation demand. <P>SOLUTION: This torque control device is provided with a demand torque calculation means 12 calculating demand torque according to an operation condition of an accelerator pedal 9, a restriction torque calculation means 12 calculating restriction torque predetermined by limitation of exhaust emission, a target torque calculation means 12 setting smaller one of demand torque and restriction torque as target torque, an averaging control means 12 performing the averaging control of the target torque in a process changing torque of the internal combustion engine from torque before increase to torque after increase when the target torque increases, and a transient torque control means 12 controlling torque of the internal combustion engine to start the averaging control from change over torque larger than torque before increase and smaller than torque after increase when dulling process is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a torque control device for a vehicle.

  In order to obtain smooth acceleration performance and smoke suppression effect of an internal combustion engine mounted on a vehicle, there is known one that performs so-called smoothing control during transient operation of the internal combustion engine. For example, it is known that the initial fuel injection amount of smoothing control at the time of acceleration is calculated as a value as large as possible that can prevent smoke according to the engine speed (Patent Document 1). In addition, there are Patent Documents 2 to 4 as prior art documents related to the present invention.

JP 2001-159356 A JP-A-7-158483 JP 2001-73839 A JP-A-5-133257

  In Patent Document 1, the initial fuel injection amount is calculated based only on the rotational speed of the internal combustion engine, and the operation state of the accelerator pedal is not taken into consideration. For this reason, the torque at the initial stage of acceleration is set to be substantially constant regardless of the operation state of the accelerator pedal, and there is a concern that acceleration shock may occur depending on the driving conditions.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle torque control device capable of obtaining a good initial response while satisfying the requirement for smooth acceleration performance and exhaust emission restriction.

  A torque control device according to the present invention is a vehicle torque control device that sets a target torque according to an operating state of an internal combustion engine mounted on a vehicle and performs torque control of the internal combustion engine based on the set target torque. Request torque calculating means for calculating the required torque in accordance with the operating state of the accelerator pedal, constraint torque calculating means for calculating a predetermined constraint torque by limiting exhaust emission, the required torque calculating means, and the constraint torque Comparing the calculation results of the calculation means, the target torque calculation means for setting the smaller target torque, and when the target torque increases, the torque of the internal combustion engine is changed from the torque before the increase to the torque after the increase. Smoothing processing means for smoothing the target torque at a predetermined smoothing degree in the process, and the smoothing processing means When performing the processing, a transient for controlling the torque of the internal combustion engine so that the smoothing processing is started from a predetermined torque that is larger than the torque before the increase and smaller than the torque after the increase. The above-mentioned problem is solved by providing the torque control means.

  According to the present invention, the required torque calculated according to the operation state of the accelerator pedal is compared with the constraint torque determined in advance by the exhaust emission limitation, and the smaller one is calculated as the target torque. Satisfy the restriction requirements. When the target torque increases, the target torque smoothing process starts from a predetermined torque that is larger than the torque before the increase and smaller than the torque after the increase. A feeling of acceleration can be given to the driver, and more effective acceleration feeling can be given to the driver as compared with a mode in which the smoothing process is started from the torque before the change.

  The torque control device of the present invention may further include switching torque setting means for setting a switching torque necessary for obtaining a minimum initial acceleration that the driver expects in the early stage of acceleration as the predetermined torque. 2). In this case, since the switching torque is set as the predetermined torque, the minimum acceleration feeling that the driver expects in the early stage of acceleration can be given to the driver, and the feeling of acceleration can be eliminated.

  When the switching torque set as described above is compared with the target torque, the target torque may not exceed the switching torque. Such a driving state is often a state where the driver does not expect an initial acceleration feeling, for example, when the driver depresses the accelerator pedal to adjust the vehicle speed. In such an operating state, the possibility of an acceleration shock is low. Therefore, as one form of the torque control device of the present invention, when the target torque does not exceed the switching torque, the smoothing processing means starts the torque before the increase and uses the predetermined smoothing degree. The annealing process may be performed with the target torque smaller than when the switching torque exceeds the switching torque, or the annealing process may be prohibited (Claim 3).

  In the torque control device of the present invention, the switching torque setting means may set the switching torque according to an operation state of an accelerator pedal. In this case, since the switching torque is set reflecting the degree of acceleration of the driver, for example, the driver can be given initial responsiveness corresponding to an acceleration request such as slow acceleration or sudden acceleration, that is, an initial acceleration feeling.

  In the torque control device of the present invention, the switching torque setting means may set the switching torque according to a gear stage of a transmission. In this case, for example, by setting the switching torque at the high speed stage to be larger than the switching torque at the low speed stage, the acceleration shock at the low speed stage is suppressed and the acceleration performance at the high speed stage is improved. can do.

  In the torque control device of the present invention, the switching torque setting means may set the switching torque according to road information (Claim 6). In this case, for example, it is possible to set a switching torque smaller than that at other times when there is a traffic jam and a switching torque larger than that when the vehicle is climbing up. .

  In the torque control device of the present invention, the switching torque setting means may set the switching torque according to vehicle loading information (Claim 7). In this case, for example, the switching torque can be optimized according to the number of passengers and the loading capacity.

  In the torque control device of the present invention, the torque control device further includes a changeover switch that detects a request for an acceleration tendency of the driver by an operation of the driver, and the changeover torque setting means sets the changeover torque according to an operation state of the changeover switch. (Claim 8). In this case, the switching torque can be selected based on the driving preference of the driver.

  In the torque control device of the present invention, the smoothing processing unit may set the predetermined smoothing degree in accordance with an operation state of an accelerator pedal. In this case, in response to an acceleration request such as slow acceleration or sudden acceleration, it is possible to give the driver a feeling of acceleration suitable for it.

  As described above, according to the present invention, the target torque is compared with the required torque and the constraint torque, and when the target torque is increased, the torque is larger than the torque before the increase and the torque after the increase. Since the target torque smoothing process is started from a predetermined torque having a smaller value, a satisfactory initial response can be obtained while satisfying smooth acceleration performance and exhaust emission restriction requirements.

(First embodiment)
FIG. 1 shows an embodiment of an internal combustion engine to which the torque control device of the present invention is applied. The internal combustion engine 1 is mounted on a vehicle (not shown) and is configured as a reciprocating diesel engine in which a piston 3 connected to a crankshaft 4 reciprocates in a plurality of cylinders 2 (only one is shown in FIG. 1). . The internal combustion engine 1 includes an intake passage 5 and an exhaust passage 6, and an intake valve 7 and an exhaust valve 8 that open and close these are provided in the intake passage 5 and the exhaust passage 6. An injection nozzle 10 is provided above the cylinder 2 so as to face the cylinder 2. The injection nozzle 10 is connected to, for example, a common rail fuel supply device 11. The operation of the fuel supply device 11 is controlled by an engine control unit (ECU) 12, and fuel is injected from the injection nozzle 10 at an appropriate injection timing and injection period (injection amount). Thereby, the torque of the internal combustion engine 1 is appropriately controlled, and the ECU 12 functions as a torque control device of the present invention in which the torque of the internal combustion engine 1 is appropriately controlled. The ECU 12 is a computer having a configuration such as a microprocessor, a RAM, and a ROM, and signals from various sensors that detect the operating state of the internal combustion engine 1 are input to the ECU 12. FIG. 1 shows a rotational speed sensor 13 for detecting the engine rotational speed (rotational speed), an accelerator sensor 14 capable of detecting an operation state such as an opening degree, a displacement amount, a stepping speed, an acceleration, and a pedaling force of an accelerator pedal 9, and an intake. An air flow meter 15 that detects the amount of air and a vehicle speed sensor 16 that detects the speed (vehicle speed) of the vehicle are shown.

Next, torque control according to the present embodiment will be described. FIG. 2 is a flowchart showing the procedure of the torque control routine. The program of this control routine is stored in the ROM of the ECU 12, and when the target torque of the internal combustion engine 1 increases, in this embodiment, when the target torque increases discontinuously beyond a predetermined change amount, the ECU 12 Repeatedly. This predetermined change amount is appropriately set according to the internal combustion engine to which the present invention is applied. First, in step S1, the ECU 12 refers to the input signal from the accelerator sensor 14 and acquires the accelerator opening degree accp. In the subsequent step S2, the ECU 12 calculates a required torque T _dem according to the accelerator opening degree accp. As shown in FIG. 3, the required torque T _dem is calculated by previously storing a map in which the required torque T _dem is related to the accelerator opening degree accp and the engine speed Ne in the ROM of the ECU 12, and refer to this map. This can be achieved. The engine speed Ne is acquired based on an input signal from the speed sensor 13. By executing step S2, the ECU 12 functions as the required torque calculation means of the present invention.

Next, in step S3, the ECU 12 calculates a restriction torque T _grd that is determined in advance by limiting exhaust emissions such as smoke. When the torque of the internal combustion engine 1 exceeds the constraint torque T _grd , exhaust emission exceeding a specified value is _caused . That is, the constraint torque T _grd is the upper limit value of the allowable range of exhaust emission. The constraint torque T _grd can be calculated by previously storing a map correlated with the intake air amount in the ROM of the ECU 12 and referring to this map. The intake air amount is acquired from an input signal from the air flow meter 15. By executing step S3, the ECU 12 functions as the constraint torque calculation means of the present invention.

In subsequent step S4, the ECU 12 calculates a target torque T _trg . In the present embodiment, the required torque T _dem calculated in step S2 is compared with the constraint torque T _grd calculated in step S3, and the smaller one is set as the target torque T _trg . FIG. 4 shows an example of the relationship _among the target torque T _trg , the required torque T _dem , and the constraint torque T _grd . Thus in the figure, until _{t 1} when the acceleration start time _{t 0} to an increase in the target torque is started with the constraint torque _{T grd} and required torque _{T dem} intersect, the required torque _{T dem} exceeds the constraint torque _{T grd.} For this reason, the target torque T _trg during this period becomes equal to the constraint torque T _grd . And after time _{t 1} because the required torque _{T dem} below constraint torque _{T grd,} after time _{t 1} of the target torque _{T trg} becomes equal to the required torque _{T dem.} Therefore, in FIG. 4, the calculated target torque T _trg is indicated by a solid line that starts at time t ₀ and bends at time t ₁ . By executing this step S4, the ECU 12 functions as the target torque calculating means of the present invention.

Next, in step S5, the ECU 12 compares the target torque T _trg calculated in step S4 with the switching torque T _chg . The switching torque T _chg is a value necessary for obtaining the minimum initial acceleration that the driver expects in the early stage of acceleration, and is set in advance corresponding to the operating state of the internal combustion engine 1 such as the engine speed. Since the initial acceleration expected by the driver, that is, the acceleration feeling experienced by the driver in the early stage of acceleration, varies depending on the driving state, the specific value of the switching torque T _chg depends on the operating state of the internal combustion engine 1 either experimentally or ergonomically. It is preset from the viewpoint. In the present embodiment, a map in which the switching torque T _chg is associated with the operating state of the internal combustion engine 1 is stored in the ROM of the ECU 12, and the ECU 12 identifies the switching torque T _chg used in step S5 by referring to this map. is doing. By executing this process, the ECU 12 functions as the switching torque setting means of the present invention.

When it is determined in step S5 that the target torque T _trg exceeds the switching torque T _chg (Yes), the ECU 12 advances the process to step S6. In step S6, the ECU 12 increases the torque of the internal combustion engine 1 to a switching torque T _chg as a predetermined torque, as shown in FIG. In this case, the switching torque T _chg is larger than the torque T ₀ before the increase and smaller than the target torque T _trg . In the present embodiment, the ECU 12 uses the switching torque T _chg as a command torque, and controls the operation of the fuel supply device 11 so that fuel is injected with a fuel injection amount corresponding to the command torque. This control may be executed after a predetermined time from the determination of the increase in the target torque. In the next step S7, the ECU 12 determines the degree of smoothing a used in the subsequent annealing process. The degree of smoothing a is a coefficient that defines a smooth asymptotic _{approach to a} target torque T _trg1 (see FIG. 5) that is larger than the switching torque T _chg , and its value is set in advance. Next, in step S8, the ECU 12 executes the _smoothing process of the target torque T _{trg1 with} the _smoothing degree a using the switching torque T _chg as a starting point. The annealing process may be performed by an appropriate method, for example, a first-order lag generally used for the annealing process may be used. Thus, as shown in FIG. 5, the _smoothing process is started from the switching torque T _chg and the target torque T in the process of changing the torque of the internal combustion engine 1 from the torque T ₀ before the increase to the torque T _trg1 after the increase. _{trg1 is} annealed.

On the other hand, when it is determined in step S5 that the target torque T _trg does not exceed the switching torque T _chg (No), the ECU 12 proceeds with the process to step S9 and determines the smoothing degree b. The degree of smoothing b is set to a value smaller than the degree of smoothing a. For this reason, when the annealing process is performed at the degree of annealing b, the asymptotic gradient becomes sharper than when the degree of annealing a is used. That is, the degree of annealing is reduced. Next, the ECU 12 proceeds to the above-described step S8, and _{smoothes the} target torque T _trg2 (the target torque T _trg smaller than the switching torque T _chg ) with the _smoothing degree b starting from the torque T ₀ immediately before acceleration. I do. Thereby, as shown in FIG. 5, the target torque T _{trg2 in the} initial _{stage of} acceleration is _smoothed . Note that the _annealing process of the target torque T _trg2 may be prohibited. In this case, the smoothing process may be prohibited by setting the smoothing degree b to 0 (zero), or the control routine may be terminated once by omitting step S9. By executing the above steps S6 to S9, the ECU 12 functions as an annealing process means and a transient torque control means of the present invention.

  Next, in step S10, the ECU 12 calculates a command torque based on the result of the annealing process in step S8, and the fuel supply device 11 performs fuel injection at a fuel injection amount corresponding to the calculated command torque. This routine is finished by controlling the operation.

According to the above embodiment, as shown in FIG. 5, the target torque T _{trg1 is} smoothed in the process of changing the torque of the internal combustion engine 1 from the torque T ₀ before the increase to the torque T _trg1 after the increase. Occurrence is suppressed. Then, the torque of the internal combustion engine 1 is increased to switch the torque T _chg before performing the smoothing process, then, since better processing from the switching torque T _chg is started, as it is clear from FIG. 6, before increasing Compared with the mode (broken line L) in which the smoothing process is executed with the torque T ₀ as the starting point Q, a good initial response expected by the driver can be obtained, and the feeling of stagnation of acceleration can be eliminated.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. This form is the same as that of the first embodiment except for the control routine shown in FIG. 7, and FIG. 1 is referred to for the configuration of the internal combustion engine. Further, in FIG. 7, the processes common to those in FIG. As shown in FIG. 7, in this embodiment, step S100 for calculating the switching torque T _chg is added. In the first embodiment, the switching torque T _chg is set in advance corresponding to the operating state of the internal combustion engine 1. However, in this embodiment, the switching torque T _chg is set according to the operating state of the accelerator pedal 9. As an example, the switching torque T _chg set corresponding to the operating state of the internal combustion engine 1 may be corrected according to the amount of displacement of the accelerator pedal 9. In this case, the base torque is specified from the map of the switching torque T _chg used in the first embodiment. Then, the correction value is specified from the map that defines the correction value corresponding to the amount of displacement of the accelerator pedal 9, and the switching value T _chg is calculated by adding the specified correction value to the base torque. This correction value is set so as to increase as the amount of displacement of the accelerator pedal 9 increases. As a result, the switching torque T _chg is calculated to be larger as the displacement amount is larger, so that it is possible to give the driver an initial response in response to an acceleration request such as slow acceleration or rapid acceleration, that is, a feeling of acceleration.

(Third embodiment)
Next, a third embodiment of the present invention will be described. This form is the same as that of the first embodiment except for the control routine shown in FIG. 8, and FIG. 1 is referred to for the configuration of the internal combustion engine. Further, in FIG. 8, the same processes as those in FIG. In this embodiment, step S200 for calculating the smoothing degree a and the smoothing degree b from the operation state of the accelerator pedal 9 is added. As an example, the calculation of the degree of smoothing a and the degree of smoothing b may be realized by referring to maps that give the degree of smoothing a and the degree of smoothing b according to the displacement amount of the accelerator pedal 9, respectively. . In this map, the degree of smoothing a and the degree of smoothing b are set to be smaller as the displacement amount of the accelerator pedal 9 is larger. According to this embodiment, when the amount of displacement of the accelerator pedal 9 is large, the degree of _smoothing of the target torque T _trg is small, so that a sharp acceleration feeling can be obtained. On the contrary, when the amount of displacement is small, a moderate acceleration feeling can be obtained. Therefore, in response to an acceleration request such as slow acceleration or rapid acceleration, it is possible to give the driver a feeling of acceleration suitable for it.

  This invention is not limited to the above embodiment, You may implement with a various form. The form of the internal combustion engine to which the torque control device of the present invention is applied is not particularly limited, and can be applied to a gasoline engine.

The basis of calculation of the required torque T _dem is not limited to the accelerator opening degree accp, and the operation state of the accelerator pedal 9 represented by the displacement amount, the depression speed, the acceleration, the depression force, etc. of the accelerator pedal 9 may be used as the calculation basis. . The operating state of the accelerator pedal 9 can be detected by the accelerator sensor 14. Similarly, in the second and third embodiments, when calculating the switching torque T _chg , the smoothing degree a, and the smoothing degree b, in addition to the displacement amount of the accelerator pedal 9, the depression speed, the acceleration, These may be combined as appropriate in consideration of the pedal effort and the like. When the depression speed of the accelerator pedal 9 is detected, it is possible to discriminate between slow acceleration and sudden acceleration even when the displacement amount of the accelerator pedal 9 is equal. Further, when the acceleration of the accelerator pedal 9 is detected, an acceleration peak is obtained at the initial depression of the accelerator pedal, so that an acceleration request can be estimated based on this peak. Therefore, it is possible to obtain an acceleration request earlier than when detecting the displacement amount and the depression speed of the accelerator pedal, and reduce the response delay. Furthermore, when the depression force of the accelerator pedal 9 is detected, it is possible to detect the degree of acceleration request before the accelerator pedal 9 is displaced, so that the acceleration request is obtained more quickly than the form in which the acceleration of the accelerator pedal 9 is detected. be able to.

The switching torque T _chg may be set according to the gear position of a transmission (not shown). In this case, for example, a map in which the switching torque T _chg at the time of the high speed is set higher than that at the low speed is stored in advance in the ROM of the ECU 12, and the ECU 12 acquires the current speed. The switching torque T _chg may be set. The detection of the shift speed may be realized based on an input signal from this sensor provided with a shift speed sensor (not shown) for detecting the shift speed in the internal combustion engine 1. As a result, acceleration shock at the low speed stage can be suppressed and acceleration at the high speed stage can be improved.

Further, the switching torque T _chg may be set according to road information. For example, a switching torque smaller than that can be set when the vehicle is congested, and a switching torque larger than that can be set when the vehicle is climbing up. The detection of whether or not there is a traffic jam may be realized based on the magnitude of the average vehicle speed while the ECU 12 obtains the average vehicle speed for a predetermined time from the input signal of the vehicle speed sensor. The detection of whether or not the vehicle is climbing may be realized based on the ECU 12 specifying changes in the load and the vehicle speed of the internal combustion engine 1.

Further, the switching torque T _chg may be set according to the vehicle loading information. In this case, the switching torque T _chg may be set to increase as the vehicle loading amount increases. According to this, for example, the switching torque can be optimized according to the number of passengers and the loading capacity. In this case, the ECU 12 may calculate the total weight from the speed change (acceleration) of the vehicle, and subtract the vehicle weight prepared in advance from the total weight to obtain the loading amount, the number of passengers, etc. A seating sensor (not shown) may be provided to detect the number of passengers.

Furthermore, the switching torque T _chg may be set according to the operating state of the driver changeover switch 20 (FIG. 1). The change-over switch 20 displays options such as a sport mode in which a sharp acceleration feeling is obtained and a family mode in which a gentle acceleration feeling is obtained. ECU12 grasps the operation state of changeover switch 20 from the input signal inputted according to operation of changeover switch 20 of a driver, and chooses change torque _Tchg set up beforehand according to the operation state of changeover switch 20. . According to this, the switching torque can be selected based on the driving preference of the driver.

The figure which showed one Embodiment of the internal combustion engine to which the torque control apparatus of this invention was applied. The flowchart which showed the procedure of the torque control routine. The figure which showed an example of the map which linked | related the required torque with the throttle opening and the engine speed. The figure which showed an example of the relationship between a target torque, a request | requirement torque, and a constraint torque. Explanatory drawing explaining the control content of the torque control apparatus of this invention. Explanatory drawing which compared the form shown in FIG. 5, and the form which performs an annealing process by using the torque just before acceleration as a starting point. The flowchart which shows the procedure of the torque control routine which concerns on 2nd Embodiment. The flowchart which shows the procedure of the torque control routine which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 9 Accelerator pedal 12 ECU (Request torque calculation means, restriction torque calculation means, target torque calculation means, smoothing processing means, transient torque control means)
20 changeover switch

Claims (9)

A torque control device for a vehicle that sets a target torque according to an operating state of an internal combustion engine mounted on a vehicle and performs torque control of the internal combustion engine based on the set target torque,
Requested torque calculating means for calculating required torque in accordance with the operating state of the accelerator pedal, restricted torque calculating means for calculating a restricted torque predetermined by limiting exhaust emission, the requested torque calculating means, and the restricted torque calculating means The target torque calculation means for comparing the calculation results of each of the two and the target torque calculation means that the smaller target torque, and in the process of changing the torque of the internal combustion engine from the torque before the increase to the torque after the increase when the target torque increases An annealing process means for performing the target torque annealing process at a predetermined degree of smoothing, and when the annealing process is performed by the annealing process means, the torque is larger than the torque before the increase and after the increase A transient torque control method for controlling the torque of the internal combustion engine so that the smoothing process is started from a predetermined torque having a value smaller than the torque of When, the torque control apparatus for a vehicle, characterized by comprising.   2. The vehicle torque according to claim 1, further comprising switching torque setting means for setting a switching torque necessary for obtaining a minimum initial acceleration that the driver expects at an early stage of acceleration as the predetermined torque. Control device.   When the target torque does not exceed the switching torque, the smoothing processing unit starts with the torque before the increase and makes the predetermined smoothing degree smaller than when the target torque exceeds the switching torque. The vehicle torque control device according to claim 2, wherein the annealing process is performed or the annealing process is prohibited.   4. The vehicle torque control device according to claim 2, wherein the switching torque setting unit sets the switching torque according to an operation state of an accelerator pedal. 5.   The vehicle torque control device according to claim 2 or 3, wherein the switching torque setting means sets the switching torque in accordance with a shift stage of a transmission.   The vehicle torque control device according to claim 2 or 3, wherein the switching torque setting means sets the switching torque according to road information.   The vehicle torque control device according to claim 2 or 3, wherein the switching torque setting means sets the switching torque according to vehicle loading information. It has a changeover switch that detects the driver's acceleration tendency request by operating the driver,
5. The vehicle torque control device according to claim 2, wherein the switching torque setting unit sets the switching torque in accordance with an operation state of the change-over switch. 9. The vehicle torque control device according to claim 1, wherein the smoothing processing unit sets the predetermined smoothing degree in accordance with an operation state of an accelerator pedal. 10.

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