JP3986471B2 - Vehicle travel control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle travel control device.
[0002]
[Prior art]
When starting or accelerating the vehicle, to prevent excessive slip of the drive wheels and improve straight running stability and acceleration, set the drive wheel rotation speed target value and set the drive wheel slip amount to a predetermined value. Some drive torque feedback control is performed so that the value is less than or equal to the value, and when the automatic transmission shifts up during this feedback control, the engine speed is temporarily lowered to suppress slip that occurs during the shift up. There is one in which the engine speed is restored when the upshifting is completed (Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 5-213099
[Problems to be solved by the invention]
However, such control has the following problems when traveling on a low μ road having a small friction coefficient μ.
[0005]
In other words, the drive torque is reduced if there is a slip after the up-shift is performed and the engine speed is restored. In this case, if the slip is large and the vehicle speed decreases, the vehicle may enter the down-shift region. is there. Therefore, the gear is shifted down immediately after the up-shifting, so that the optimum shift cannot be performed and the running performance may be deteriorated.
[0006]
An object of the present invention is to ensure good running performance on a low μ road.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a vehicle including an accelerator opening detecting means, a vehicle speed detecting means, and a shift control means for performing a shift control of the automatic transmission based on the accelerator opening and the vehicle speed. The slip ratio detecting means for detecting and the slip ratio are set with a first set value and a second set value larger than the first set value, and the first set value is a driving wheel provided in the vehicle. slip is set to more than the slip rate of occurrence of the second set value, the vehicle is set to the slip ratio becomes impossible travel, when the slip ratio of the driving wheels is equal to or greater than the first set value, the shift The shift point for the up vehicle speed is set higher than the shift up shift point for the vehicle speed when the vehicle speed is less than the first set value, and the shift point for the vehicle speed of the shift down is less than the first set value. As lower than the shift point for the vehicle speed of Futodaun, the shift point change unit that changes the shifting point of the automatic transmission by the shift control means when the slip ratio of the driving wheels is equal to or higher than the second set value, the slip ratio Engine torque suppression control means for suppressing the torque of the engine in response.
[0009]
In a second aspect based on the first aspect , the engine torque suppression control means has a large slip ratio detected by the slip ratio detection means when the slip ratio of the drive wheel is not less than the second set value. By calculating the engine torque correction value having a larger value, and subtracting the calculated engine torque correction value from the required torque calculated based on the accelerator opening and the engine speed, the engine The fuel injection amount is determined, and the engine torque is suppressed.
[0010]
【The invention's effect】
In the first and second aspects of the invention, it is possible to avoid an excessive shift with respect to slip and to perform good running and stable driving.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system schematic diagram of a form applied to a parallel hybrid vehicle, where 1 is an engine, 2 is a rotating electrical machine (motor generator), and the engine 1 and the rotating electrical machine 2 are automatically connected via clutches 3 and 4 respectively. It is connected to a transmission 5 and the output of the automatic transmission 5 is transmitted to driving wheels 6 as rear wheels.
[0012]
As the engine 1, a diesel engine (or a CNG engine using compressed natural gas as fuel) is employed. The rotary electric machine 2 uses a permanent magnet type synchronous motor from the viewpoint of high efficiency and reduction in size and weight.
[0013]
The engine 1 is controlled by an engine control unit (engine ECU) 7. The engine control unit 7 detects a request of the vehicle control unit 8 and a detection of an accelerator opening sensor 11 that detects a depression amount (accelerator opening) of an accelerator pedal 10. The fuel injection (injection amount, etc.) of the engine 1 is controlled according to the signal, the detection signal of the engine rotation sensor 12 for detecting the rotation speed of the engine 1 and the like.
[0014]
The rotating electrical machine 2 is controlled by an inverter (not shown), and the inverter drives the rotating electrical machine 2 with electric power of a power storage device (not shown) in the electric mode in response to a request from the vehicle control unit 8, while in the power generation mode. The power storage device is charged with regenerative electric power from the rotating electrical machine 2.
[0015]
The automatic transmission 5 is controlled by the shift control unit 13, and the shift control unit 13 includes requests from the vehicle control unit 8 (including instructions such as an automatic shift mode of the cab shift instruction device, a shift up and a shift down), The gear shift of the automatic transmission 5 is controlled according to the detection signal of the gear position sensor 14 for detecting the gear position.
[0016]
The clutches 3 and 4 are controlled to be connected / disconnected by the vehicle control unit 8 via a clutch actuator 15 (only one is shown).
[0017]
The vehicle control unit 8 sets the output sharing between the engine 1 and the rotating electrical machine 2 based on the driving region at the time of start, acceleration, steady running, and the amount of power stored in the power storage device. Based on the required driving force (accelerator opening degree or the like), the output of the engine 1 and the output of the rotating electrical machine 2 are controlled via the engine control unit 7 and the inverter.
[0018]
The vehicle control unit 8 is based on the accelerator opening and the vehicle speed (converted from the rotational speed of the engine 1 and the gear position of the automatic transmission 5 or from the rotational speed of the rotating electrical machine 2 and the gear position of the automatic transmission 5). Are provided with a shift map in which the shift range of the automatic transmission 5 in the normal state is set, and a shift map in which the shift range of the automatic transmission 5 in the slip state is set. Therefore, the detection signals of the wheel speed sensors 20 to 23 that control the upshift and downshift of the automatic transmission 5 and detect the rotational speeds of the front wheels 16 and the rear wheels (drive wheels) 6 through the shift control unit 13. Based on the above, the slip state of the drive wheel 6 is measured, and when slip occurs, the shift map is switched to the shift map at the time of slip and slip control is performed.
[0019]
The clutches 3 and 4 are controlled according to the output sharing between the engine 1 and the rotating electrical machine 2 and the shift map of the automatic transmission 5.
[0020]
Next, slip control during traveling by the engine 1 will be described.
[0021]
FIG. 2 shows the functional block configuration of the slip control. The slip ratio determining means 30, the shift map section 31, the automatic shift control means 32, the shift means 33 (shift control unit, clutch 3), and the engine torque map section 34 are shown. , An engine correction torque calculation means 35, an engine suppression correction means 36, and an engine control means 37 (engine control unit).
[0022]
The slip ratio determining means 30 determines the slip ratio of the drive wheel 6 from the wheel speed of the front wheel 16 and the wheel speed of the rear wheel (drive wheel) 6.
[0023]
If the slip ratio is less than a first set value (for example, 10%), the shift map unit 31 selects a normal shift map and issues a shift request according to the accelerator opening and the engine rotation. When the slip ratio is equal to or higher than the first set value, a shift map at the time of slip is selected, and a shift request is issued according to the accelerator opening and the engine rotation.
[0024]
In the case of the shift map at the time of slip, the shift point for the upshift is set, for example, by 500 rpm higher for the engine speed, and the shift point for the downshift is set, for example, by 500 rpm lower for the engine speed.
[0025]
The automatic shift control means 32 issues a control signal to the shift means 33 in response to the shift request of the shift map section 31.
[0026]
The engine torque map unit 34 outputs a required torque of the engine based on the accelerator opening and the engine rotation.
[0027]
The engine correction torque calculation means 35 is configured to reduce the accelerator opening so as to suppress the engine torque when the slip ratio of the slip ratio determination means 30 is greater than or equal to a second set value (for example, 30%> first set value). An engine torque correction value is calculated based on the engine rotation and the slip ratio.
[0028]
The engine torque correction value is set to take a larger value as the slip ratio is larger.
[0029]
When the engine torque correction value of the engine correction torque calculation means 35 is 0, the engine suppression correction means 36 instructs the engine control means 37 to request the torque requested by the engine torque map unit 34, and the engine torque of the engine correction torque calculation means 35. If the correction value is not 0, the engine torque correction value of the engine correction torque calculation means 35 is subtracted from the required torque of the engine torque map unit 34 and the engine control means 37 is commanded.
[0030]
The engine control means 37 controls fuel injection (injection amount or the like) of the engine 1 based on the command.
[0031]
FIG. 3 shows a flowchart of the slip control. In S1, the slip ratio of the drive wheel 6 is calculated from the wheel speed of the front wheel 16 and the wheel speed of the rear wheel (drive wheel) 6.
[0032]
In S2, it is checked whether or not the slip ratio of the drive wheels 6 is larger than a set value 1 (for example, 10%).
[0033]
When it is smaller than the set value 1, in S3, a normal shift process is executed using a normal shift map.
[0034]
If it is greater than the set value 1, it is checked in S4 whether it is greater than the set value 2 (for example, 30%> set value 1).
[0035]
When the slip ratio of the drive wheel 6 is larger than the set value 1 and smaller than the set value 2, the process proceeds to S7, and the shift map is switched to the shift map at the time of slip.
[0036]
In S8, a shift command is output according to the shift point of the shift map.
[0037]
On the other hand, when the slip ratio of the drive wheel 6 is larger than the set values 1 and 2, the process proceeds to S5 and S6, and the engine torque correction value is calculated based on the accelerator opening, the engine rotation, and the slip ratio, and the engine torque is calculated. Control to suppress.
[0038]
In S7, the shift map is switched to the shift map at the time of slip.
[0039]
In S8, a shift command is output according to the shift point of the shift map.
[0040]
With such a configuration, when the drive wheel 6 slips and the slip ratio is equal to or greater than the set value 1, the shift-up point of the upshift is set higher than the shift map at the normal time, and the shift point of the downshift is set. It is possible to switch to the shift map when the slip is lowered.
[0041]
In this case, if the slip ratio is not so large (less than the set value 2), the engine torque is controlled to a required torque based on the accelerator opening and the engine rotation.
[0042]
That is, when the slip rate is not so large, the engine torque is not suppressed and the shift point for the upshift with respect to the increase in the vehicle speed is increased, while the shift point for the downshift with respect to the decrease in the vehicle speed is decreased. Change the shifting point . When the increase in the vehicle speed reaches a speed change point, the shift-up is performed, the engine speed during shifting so that by increasing the shifting point of shift-up for the increase of the vehicle speed is higher than normal, the shift point of the shift-down for down speed Since it is low, it will not enter the downshift area, and good driving can be secured.
[0043]
If the slip ratio is large (set value 2 or more), the engine torque is suppressed according to the slip ratio.
[0044]
That is, when the slip ratio is large, the shift point is delayed and the engine torque is suppressed, so that the slip is suppressed and the shift up / down that is too early with respect to the increase / decrease of the vehicle speed is prevented. Therefore, excessive gear shifting is avoided, and upshifting and downshifting are performed in accordance with the vehicle speed and slip, so that stable driving and traveling can be performed.
[0045]
According to such a configuration, it is possible to ensure a stable start running particularly on a low μ road.
[0046]
On the other hand, when traveling by the rotating electrical machine 2, the control data related to the engine 1 described above may be replaced with that of the rotating electrical machine 2. In addition, when the engine 1 and the rotating electrical machine 2 are used in combination, torque suppression may be performed by the rotating electrical machine 2.
[Brief description of the drawings]
FIG. 1 is a system outline diagram showing an embodiment of the present invention.
FIG. 2 is a block diagram of a control system.
FIG. 3 is a flowchart of slip control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Rotating electrical machine 3, 4 Clutch 5 Automatic transmission 6 Drive wheel 7 Engine control unit 8 Vehicle control unit 11 Accelerator opening sensor 12 Engine rotation sensor 13 Shift control unit 14 Gear position sensor 16 Front wheels 20-23 Wheel speed sensor

Claims (2)

In a vehicle comprising accelerator opening detection means, vehicle speed detection means, and shift control means for performing shift control of an automatic transmission based on the accelerator opening and vehicle speed,
Slip ratio detection means for detecting the slip ratio of the drive wheel;
In the slip ratio, a first set value and a second set value larger than the first set value are set,
The second set value is set to a slip ratio at which the vehicle cannot travel,
When the slip ratio of the drive wheel is equal to or higher than the first set value, the shift point for the upshift vehicle speed is set higher than the shift up shift point for the vehicle speed when the shift speed is less than the first set value. Shift point changing means for changing the shift point of the automatic transmission by the shift control means so that the shift point with respect to the vehicle speed is lower than the shift point with respect to the vehicle speed of the downshift in the case of less than the first set value ;
A vehicle travel control device comprising engine torque suppression control means for suppressing engine torque in accordance with the slip ratio when the slip ratio of the drive wheel is equal to or greater than the second set value. The engine torque suppression control means includes
When the slip ratio of the drive wheel is equal to or greater than the second set value, the larger the slip ratio detected by the slip ratio detection means, the larger the engine torque correction value is calculated.
By subtracting the calculated engine torque correction value from the required torque calculated based on the accelerator opening and the engine speed, the fuel injection amount of the engine is determined and the engine torque is suppressed. The travel control device for a vehicle according to claim 1 .

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