JP2525684B2 - Method for controlling rotational speed of internal combustion engine for driving vehicle - Google Patents

Description

The present invention relates to a rotational speed control method for an internal combustion engine for driving a vehicle equipped with an automatic transmission.

(Prior Art) In recent years, a vehicle equipped with an electronically controlled automatic transmission that electronically controls the operation of a gear transmission and a clutch has been widely put into practical use. In a vehicle equipped with an automatic transmission of this type, it is generally necessary to prevent an unnecessary increase in rotation of the internal combustion engine during vehicle start control. A configuration is known in which the engine speed control mode is set to a mode different from the engine speed control mode during the other normal operation period so that the engine speed does not increase unnecessarily during the start control operation ( For example, JP-A-61-196831).

(Problem to be Solved by the Invention) However, as described above, according to the configuration in which the control mode for controlling the engine speed is switched, the acceleration of the vehicle is changed when the control mode is changed at the time when the vehicle is completely started. It has a problem that it changes drastically and the ride feeling is impaired.

An object of the present invention is to suppress an unnecessary increase in the engine rotation speed during vehicle start control without switching the speed control mode for controlling the engine rotation speed, and to impair the riding feeling after completion of the vehicle start. It is an object of the present invention to provide a method for controlling the rotational speed of an internal combustion engine for driving a vehicle, which does not cause discontinuity in acceleration of the vehicle.

(Means for Solving the Problems) A feature of the method of the present invention for solving the above-mentioned problems is that a vehicle equipped with an automatic transmission adapted to electronically control the operation of a gear transmission and a clutch is used. In a rotation speed control method for an internal combustion engine, the rotation speed control of the driving internal combustion engine is performed in a control mode for normal traveling, and the rotation speed of the driving internal combustion engine is determined according to an accelerator operation amount during a vehicle start control period. Limited to less than the upper limit,
In response to completion of the start control, gradually increase the upper limit value,
When the upper limit value reaches the maximum rotation speed value according to the control mode for normal traveling, the operation of limiting the upper limit value of the driving internal combustion engine is canceled.

The clutch connection control for starting the vehicle may take any suitable form. For example, when performing the slip ratio control in which the slip ratio of the clutch is gradually changed from 1 to 0 with the passage of time, the start control is performed. It is possible to adopt a configuration in which the increase of the upper limit value is started at a predetermined time point after a predetermined time has elapsed from the control start time point and the start control is not yet completed.

(Operation) The speed control of the internal combustion engine is executed in the control mode for normal running even during the start control period, and the upper limit value of the engine speed is determined according to the accelerator operation amount at that time. Therefore, the engine speed is controlled with the speed control timing substantially equal to the all-speed characteristic, and the engine speed does not transiently increase during the start control period. With the end of the start control,
The upper limit value gradually increases with the passage of time,
When the upper limit value reaches the maximum rotation speed value according to the control mode for normal traveling, the limiting operation of the upper limit value of the driving internal combustion engine is canceled, whereby the engine speed control is completely required for normal traveling. Run in control mode for. Therefore, the acceleration of the vehicle does not suddenly change at the end of the start control.

Further, when the clutch is engaged when the vehicle starts moving by controlling the slip ratio, the upper limit value is gradually increased at an appropriate point during the engagement. As a result, when the accelerator operation amount is kept at a relatively large value at the time of starting, the engine speed is suppressed to a lower value when the slip of the clutch is large. However, when the clutch is connected and the slip becomes smaller and reaches a predetermined value, the engine speed will increase with the decrease in the slip ratio of the clutch.
A good starting feeling can be surely obtained.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a vehicle control device constructed so that the rotational speed of an internal combustion engine for driving a vehicle is controlled by the method of the present invention. The vehicle control device 1 shown in FIG. 1 is a device that controls a vehicle (not shown) driven by an internal combustion engine 3 that receives fuel injection supply from a fuel injection pump 2. Here, the internal combustion engine is used. Three
The rotational output from the vehicle is transmitted to the drive wheels (not shown) of the vehicle through the friction clutch 4 and the gear transmission 5. A clutch actuator 6 is connected to the clutch 4, and the clutch actuator 6 performs connection (on) or disconnection (off) operation of the clutch 4 in response to a clutch control signal Sc from a control unit 7 described later. On the other hand, the transmission actuator 8 connected to the gear transmission 5 responds to a transmission control signal St from the control unit 7 and shifts the gears of the gear transmission 5.

The first detector 9 outputs a first detection signal K ₁ indicating the position of a pressure plate (not shown) of the clutch 4 operated by the clutch actuator 6, while the second detector 9
Reference numeral 10 outputs a second detection signal K ₂ indicating the actual gear position of the gear transmission 5 operated by the transmission actuator 8.
The first and second detection signals K ₁ and K ₂ are input to the control unit 7.

A first sensor 11 that outputs an input speed signal Sa indicating the input rotation speed of the clutch 4 is provided on the input side of the clutch 4, and an output speed signal Sb indicating the output rotation speed of the clutch 4 is provided on the output side of the clutch 4. A second sensor 12 for outputting is provided. The input speed signal Sa and the output speed signal Sb are input to the slip rate detection unit 13, where the slip rate of the clutch 4 at that time is calculated. The slip ratio signal SD indicating the calculation result is input to the control unit 7. The input speed signal Sa is also input to the control unit 7 as a signal indicating the rotation speed of the internal combustion engine 3.

In addition to this, the control unit 7 receives an accelerator signal AC indicating the operation amount of the accelerator pedal 14 from the accelerator sensor 15, and a select signal indicating the select position of the selector 16.
SC is input from the select sensor 17. Further, a vehicle speed signal VC indicating the vehicle speed is output from the vehicle speed sensor 18, the vehicle speed signal VC is input to the control unit 7, and a key switch signal KY indicating whether or not the key switch SW is OFF is also input to the control unit 7. Has been done.

Reference numeral 19 is a rack actuator that responds to the fuel control signal FS output from the control unit 7 to adjust the position of the control rack 2a that is the fuel adjusting member of the fuel injection pump 2. Reference numeral 20 is a water temperature sensor that outputs a water temperature signal WT indicating the cooling water temperature of the internal combustion engine 3, and the water temperature signal WT is input to the control unit 7.

The control unit 7 includes a central processing unit (CPU) 21, a random access memory (RAM) 22, a read only memory (ROM) 23, an input / output interface circuit (I / O) 24, and a bus for interconnecting these. It is constituted by a known microcomputer system including 25. The control unit 7 responds to each input signal and data, and the control program stored in the ROM 23 in advance is executed in the CPU 21, whereby the control for starting the vehicle, the engine speed control, and the control for shifting are performed. To be executed.

FIG. 2 shows a flowchart showing the control program 30 executed in the control unit 7, and the vehicle control executed by the control unit 7 will be described based on this flowchart.

The control program 30 starts to be executed when the power of the device is turned on, and in step 31, various data indicating the driving state of the vehicle according to the signal or data given to the control unit 7 is input into the microcomputer system. In the next step 32, the map data is stored in advance in the ROM 23 in accordance with the engine speed value of the internal combustion engine 3 indicated by the input speed signal Sa from the first sensor 11 and the accelerator operation amount value indicated by the accelerator signal AC. The value LP of the limit rack position under the operating condition at that time is calculated with reference to the predetermined limit speed characteristic data.

The limit speed characteristic that is the basis of this calculation is the third
It is shown in the figure. In FIG. 3, the horizontal axis represents the engine rotation speed, and the vertical axis represents the position of the control rack 2a.

Returning to FIG. 2, in step 33, based on the limit speed characteristic data corresponding to the limit speed characteristic shown in FIG. 3, the value of the full rack position indicating the maximum position of the control rack 2a according to the engine speed value at that time. FP
Is calculated. This calculation may be determined only in accordance with the engine rotation speed value, but may also be determined in response to the water temperature signal WT in consideration of the value of the engine cooling water temperature at that time.

In step 34, it is determined whether LP> FP, and LP
When ≦ FP, the determination result in step 34 is NO and the process proceeds to step 36. On the other hand, if LP> FP, the determination result in step 34 is YES, and in step 35, the content of the value LP is replaced with the content of the value FP, and then the process proceeds to step 36. That is, the data is changed so that the value of the limit rack position does not exceed the value of the full rack position.

In step 36, it is determined whether or not the flag F indicating whether or not to control the engine speed for starting control of the vehicle is set. This flag F is set / cleared by the limit value calculation program 50 shown in FIG. 4, which will be described in detail later. When the flag F is cleared (F = "0"), the determination result in step 36 is NO, the position control of the control rack 2a is controlled in accordance with the value LP in step 37, and further in step 38 the gear transmission. Other controls such as control of the clutch 5 and the clutch 4 are executed, and thereafter, the process returns to step 31.

Next, the limit value calculation program 50 will be described with reference to FIG. This limit value calculation program 50 is also RO
It is stored in the M23 in advance and is executed at a predetermined cycle. When this program 50 starts running, step 51
In the above, whether or not the control for starting the vehicle is being executed is determined by an appropriate known method. When the result of this determination is YES, the routine proceeds to step 52, where the rotation limit value K is calculated according to the characteristic diagram shown in FIG. 5 according to the accelerator operation amount and the selected position selected by the selector 16 at that time. The rotation limit value K is an upper limit value of the engine rotation speed during the vehicle start control period. When the rotation control value K is calculated in this way, the routine proceeds to step 53, where the flag F is set and this program 50
Execution ends.

On the other hand, if the start control period is not in progress, the determination result of step 51 is NO, and it is determined whether or not the flag F is set in step 54. If the flag F is not set, the determination of step 54 is made. The result is NO, and the execution of the program 50 ends. When the flag F is set, the determination result of step 54 is YES and the routine proceeds to step 55. In step 55, the amount of change ΔK indicating the amount of increase per unit time when the rotation limit value K determined in step 52 is gradually increased from a certain time point.
Is determined according to the accelerator operation amount at that time and the select position of the selector 16. In step 56, the value of the rotation limit value K is replaced with K + ΔK, and in step 57, it is judged whether or not the updated value of K is larger than a value Nmax larger than a predetermined maximum rotation speed value allowed for the engine. Is performed. If Nmax ≧ K, the determination result in step 57 is NO, and the execution of the program ends. But,
When Nmax <K, it is no longer necessary to limit the rotation, so the flag F is cleared in step 58, and the program execution ends. As described above, when the vehicle is in the start control period, the rotation limit value K is determined based on the characteristics shown in FIG. 5 and the flag F is set.

Therefore, the determination in step 36 of the control program 30 shown in FIG. 2 is YES in this case, and the process proceeds to step 39. In step 39, the position of the control rack 2a corresponding to this value K is calculated based on the rotation limit value K obtained in the limit value calculation program 50, and the limit position value MP indicating this calculated value is calculated. .

Next, at step 40, it is judged if LP> MP. If LP ≦ MP, the judgment result at step 40 is NO, and the routine proceeds to step 37. If LP> MP, the determination result in step 40 is YES, and the value LP is set to the value MP in step 41.
Is replaced by That is, when the rotation limit line (a) determined by the value MP is to the right of the limit rack line (b) shown by the value LP on the characteristic line of FIG. 3 as shown in FIG. The rotation speed is limited according to the limit rack line (b), but if the rotation limit line (b) is located to the left of the limit rack line (b) on the characteristic line in FIG. 3, the replacement in step 41 is performed. Thus, the engine speed is limited according to the rotation limit line (a).

According to the above configuration, when the vehicle is under start control,
The rotation limit value K is determined according to the characteristics of FIG. 5 and the flag F is set, so that the position of the control rack 2a is limited so that the internal combustion engine 3 is not operated beyond this rotation limit value K. Done. The rotation limit value K depends on the accelerator operation amount.

Therefore, the position of the control rack 2a is suppressed to the rotation limit value K or less according to a required value according to the operation amount of the accelerator pedal 14 with the start of the start control, and after the start control is completed, the rotation limit value K gradually increases. Increase, and finally reach the maximum rotation speed according to the required limit speed characteristic. Therefore, it is possible to effectively prevent the engine rotation speed from excessively increasing even though the rotation speed control of the internal combustion engine 3 is performed with the limit speed characteristic during the vehicle start control period. In addition, the rotation limit value gradually increases, and when the rotation limit value exceeds the maximum rotation speed value of the required limit speed characteristic, the rotation speed limiting operation due to the rotation limit value is canceled. The transition to the governor control operation according to the normal limit speed characteristic is smoothly performed, and no trouble such as a rapid change in vehicle speed at the end of start control occurs.

In the above embodiment, the configuration in which the predetermined rotation limit value is provided during the start control and the limit value is gradually increased at the predetermined rate has been described in detail. However, when the vehicle start control is performed by controlling the slip ratio of the clutch 4 to change from 1 to zero according to a predetermined pattern with the passage of time, the vehicle start control may be appropriately performed before the vehicle start control ends. By adopting a configuration in which the rotation limit value is gradually increased from the timing of, a good starting feeling can be obtained.

FIG. 6 shows an example of a control program adapted to perform start control by such a method. The flow chart shown in FIG. 6 shows a control program for a vehicle configured to perform vehicle start control according to the method of the present invention. The vehicle start program shown in FIG. 2 and FIG. The control corresponding to the control is performed.

The description will be given according to the flowchart shown in FIG. The control program is also stored in the ROM 23 in advance, and is executed by the CPU 21 at the same time when the vehicle control device 1 is powered on. This control program 60 is executed by the selector 16 in step 61 after the start of execution.
According to the select mode at that time, the rotation limit target value KM and the change amount ΔK are determined according to the accelerator operation amount. The calculation formula for this determination is predetermined as a function of the accelerator operation amount. In step 62, the start mode is determined. When the selector 16 is set to the 1, 2 or R range, the rotation limit value is not increased during the start control to prioritize the startability at low vehicle speeds. Proceed to.

In step 63, the rotation limit target value KM obtained in step 61 is compared with the limit value K defined on the limit speed characteristic diagram shown in FIG.
If K <KM, the determination result of step 63 is YES, and the value of K + ΔK is set to K in step 64. On the other hand, when K ≧ KM, the determination result in step 63 is NO, and the value of K−ΔK is set to K in step 65.

On the other hand, if the determination result in step 63 is NO, it is determined whether or not a certain waiting time has passed since the start operation was started. If the waiting time has not yet passed, the determination in step 66 is made. The result is NO, the elapsed time is measured in step 67, and the process proceeds to step 63. Step 66
If the result of the determination is YES, the routine proceeds to step 68, where it is determined whether the starting mode is the half clutch mode. If not in the half-clutch mode, that is, in the slip ratio mode, the determination result of step 68 is NO, and the routine proceeds to step 64. In the half-clutch mode, the determination result in step 68 is YES, and in step 69, the accelerator operation amount ACC
Is determined to be greater than 40%. ACC> 40
If [%], the process proceeds to step 64, and if ACC ≦ 40 [%], the process proceeds to step 63.

When the execution of step 64 or 65 is completed, the routine proceeds to step 70, where the rotation limit value K is the idle rotation speed Ni of the internal combustion engine 3.
For example, it is determined whether or not the value is larger than the value obtained by adding 200 [rpm]. The value of 200 [rpm] is determined by the inclination of the rotation limit line and the rack position when the engine rotates with no load. When K ≦ Ni + 200, the determination result of step 70 is NO, and the routine proceeds to step 71, where the rotation limit value K
Is set to Ni + 200 [rpm] and the process returns to step 61. K> Ni +
In the case of 200, the determination result of step 70 is YES and the process proceeds to step 72. At step 72, it is judged if K> Nb. Nb is the maximum rotation speed that can be allowed during start control, and is selected to be 950 [rpm], for example. If K ≦ Nb, the determination result in step 72 is NO, and the process returns to step 61. If K> Kb, in step 73 the rotation limit value K
After the value of is set to Nb, the process returns to step 61.

According to the above configuration, the vehicle is in the start control other than the selectors 1, 2 and R, and when it is determined that the waiting time is exceeded by the time measurement in step 67, the accelerator operation amount is 40 (%) with the half clutch. If the rotation limit value K is smaller than the rotation limit target value KM, K
The value of is gradually decreased or increased. in this case,
K never exceeds Ni + 200 or Nb.

When the accelerator operation amount is 40% or more or in the slip ratio control mode, the rotation limit value K is the rotation limit target value K.
Regardless of the magnitude relationship with M, it gradually increases by ΔK. This increase is set to K = Nb when K becomes larger than Nb (steps 72 and 73).

As described above, the rotation limit value K increases by ΔK when the predetermined condition is satisfied, and during the start control period, the slip ratio of the clutch 4 is decreased and the engine speed is increased, resulting in an extremely good start feeling. Obtainable. Also, during the half-clutch control, unless the accelerator operation amount is larger than a fixed value (40 [%] in the above example), the rotation limit is not removed, so that fine speed control is ensured and sudden start etc. It never happens. Also, when the accelerator operation amount exceeds 40 [%], the rotation limit value gradually increases, so a certain waiting time occurs until the rotation limit is released, and even if the accelerator pedal is suddenly depressed. , It does not become a high rotation state at the time of the clutch meet. Thus, even when the rotation gradually increases and the so-called engine loss occurs due to insufficient torque, the torque is increased and the starting performance of the vehicle can be greatly improved. Further, since the rotation limitation according to the clutch stroke is not performed, the acceleration of the vehicle can be improved regardless of the load of the vehicle.

(Effect of the Invention) According to the present invention, the engine speed is excessively increased by limiting the rotational speed of the internal combustion engine, which is controlled by the speed control characteristic for normal traveling control, to a predetermined value or less during the vehicle start control period. When the start control is completed, the rotational speed limit value is gradually increased to finally operate the engine with the speed control characteristics for normal traveling control. It is possible to prevent the engine speed from transiently increasing during start control without changing the speed control characteristics for speed control, and to reliably prevent a sudden change in vehicle speed after completion of start control. can do.

Further, in the case where the clutch is connected by the slip ratio control, the rotation limit value is gradually increased after a lapse of a certain time after the start control is started, whereby an extremely good start feeling can be obtained. ,
The engine speed can be gradually increased during the start control period, the torque can be increased even when the engine is losing due to insufficient torque, the start performance can be significantly improved, and the load condition of the vehicle can be maintained. It is possible to obtain effects such as improvement in acceleration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vehicle control device according to the present invention, FIG. 2 is a flow chart showing a control program executed in the control unit of FIG. 1, and FIG. FIG. 4 is a characteristic diagram showing the limit speed characteristic which is used by being placed, FIG. 4 is a flowchart showing a limit value calculation program executed in the control unit of FIG. 1, and FIG. 5 is a relationship between the rotation limit value and the accelerator operation amount. FIG. 6 is a flowchart showing another control program executed in the control unit of FIG. 1 ... Vehicle control device, 3 ... Internal combustion engine, 4 ... Clutch, 5 ... Gear transmission, 6 ... Clutch actuator, 7 ... Control unit, 8 ... Transmission actuator, 14 ... Accelerator pedal .

Claims (2)

(57) [Claims] 1. A method for controlling the rotational speed of an internal combustion engine for driving a vehicle equipped with an automatic transmission for electronically controlling the operation of a gear transmission and a clutch. Performed in the control mode for normal running, during the vehicle start control period, the rotational speed of the driving internal combustion engine is limited to the upper limit value or less determined according to the accelerator operation amount, and the upper limit value in response to the completion of the start control. A vehicle drive characterized by gradually increasing and releasing the upper limit value limiting operation of the driving internal combustion engine when the upper limit value reaches the maximum rotation speed value according to the control mode for normal traveling. Rotational speed control method for internal combustion engine. 2. A method for controlling the rotational speed of an internal combustion engine for driving a vehicle equipped with an automatic transmission adapted to electronically control the operation of a gear transmission and a clutch. A rotation control value that is performed in a control mode for normal running and that performs the clutch connection during the vehicle start control period by slip rate control to determine the upper limit value of the rotational speed of the driving internal combustion engine during the vehicle start control period. Is gradually increased after a predetermined timing before the start control is terminated, and the upper limit value limiting operation of the driving internal combustion engine is canceled when the upper limit value reaches the maximum rotation speed value according to the control mode for normal traveling. A method for controlling the rotation speed of an internal combustion engine for driving a vehicle, comprising: