JP2796878B2 - Vehicle driving force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vehicular drive suitable for use in, for example, reducing slip generated between wheels of a vehicle and a road surface and smoothly accelerating the vehicle. More particularly, the present invention relates to a vehicle driving force control device equipped with an automatic transmission.

[Conventional technology]

Generally, a vehicle driving force control device that calculates a vehicle slip ratio based on a vehicle body speed and a wheel speed of a vehicle and controls the output of an engine based on the slip ratio is disclosed in, for example, JP-A-1-178742. And so on.

Then, in this kind of driving force control device based on the vehicle speed V _B and the wheel speed V _W as shown in Figure 6, the slip ratio S of the vehicle which occurs between the wheel and the road surface of the vehicle, Calculated as, the slip ratio S at the time t ₁ later, for example, when it exceeds the set value S ₀ of about S = 0.3, actuates the throttle actuator or the like to limit the intake air amount of the engine, as the rotational output The slip ratio S is controlled to be reduced by lowering the driving force.

Here, in the middle of the intake passage of the engine, a throttle valve whose valve opening θ is controlled as indicated by a characteristic line 1 in FIG. 6 by an accelerator pedal, and a sub-throttle valve whose valve opening is controlled by the throttle actuator The valve opening θ of the intake valve is controlled to be smaller than the valve opening θ of the throttle valve when the throttle actuator is operated, as indicated by a characteristic line 2 shown by a dashed line in FIG. This limits the amount of intake air of the engine. When the slip ratio S becomes smaller than the set value S ₀ , the sub-throttle valve is opened by the throttle actuator, and the valve opening θ as the intake valve is controlled according to the valve opening θ of the throttle valve. You.

[Problems to be solved by the invention]

Incidentally, in the prior art described above, to detect a vehicle speed V _B and the wheel speed V _W, by the basis of these (1) calculates the slip ratio S of the vehicle, setting the slip ratio S is a predetermined value S _Since the output of the engine is controlled based on whether it exceeds ₀ , there is a time lag between when the slip actually occurs and when the control is performed, and it is difficult to perform quick control suitable for the road surface condition There's a problem.

On the other hand, recent vehicles are provided with a driving torque detecting means called a torque sensor, and detect an actual driving torque T _S. When focusing on the behavior of the driving torque T _S of the vehicle during running of the vehicle, as the characteristic line 3 of the drive torque T _S shown in FIG. 6, the slip ratio S in the slip of the vehicle is generated at time t ₁ later Starts to increase, the driving torque T _S suddenly decreases, and the behavior of the driving torque T _S is sensitive to the slip of the vehicle.

In a vehicle equipped with an automatic transmission, the input-side rotational speed N _E , the output-side rotational speed _NT of the torque converter, and the gear ratio G _R
Based on the above, the output shaft torque Tθ of the automatic transmission can be calculated as in the following equation (6). The calculated value of the output shaft torque Tθ is represented by a characteristic line 4 shown by a dotted line in FIG.
As described above, the driving torque T _S does not change so much when the vehicle slips, and the difference between the output shaft torque Tθ and the driving torque T _S increases when the vehicle slips.

The present invention has been made in view of the above-described problems of the related art, and the present invention can quickly control a driving force when a vehicle slip occurs based on a calculated value of an output shaft torque and a detected value of a driving torque, and can reduce a vehicle slip. It is an object of the present invention to provide a vehicle driving force control device capable of effectively reducing the driving force.

[Means for solving the problem]

The feature of the configuration adopted by the present invention to solve the above-described problem is that the automatic transmission is connected to the output shaft of the engine and includes a torque converter and a transmission gear mechanism, and a transmission gear mechanism of the automatic transmission. A speed ratio detecting means for detecting a speed ratio, an input speed detecting means for detecting an input speed of the torque converter, an output speed detecting means for detecting an output speed of the torque converter, and Torque detection means for detecting the driving torque of the vehicle on the output shaft side of the machine, and output torque calculation means for calculating the output torque of the torque converter based on the detection signals from the input rotation number detection means and the output rotation number detection means. An output shaft for calculating an output shaft torque of the automatic transmission based on the output torque calculated by the output torque calculating means and the speed ratio from the speed ratio detecting means; Torque calculating means, torque difference calculating means for calculating a difference between the output shaft torque calculated by the output shaft torque calculating means and the driving torque detected by the torque detecting means, and a torque difference calculated by the torque difference calculating means being a predetermined value. Torque difference determining means for determining whether the value is greater than a set value,
When the torque difference determining means determines that the torque difference is greater than a set value, the torque difference determining means reduces driving force of the vehicle by the engine.

Further, it is preferable that when the automatic transmission is in a shift state, the driving force control by the driving force control means is held or released.

[Action]

With the above configuration, a torque difference is calculated from the calculated value of the output shaft torque and the detected value of the driving torque, and it is possible to early determine the occurrence of a vehicle slip based on the torque difference, which is faster than based on the calculated value of the slip ratio. Driving force control becomes possible.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5 by taking as an example a driving force control device applied to a rear wheel drive vehicle equipped with an automatic transmission.

In the figure, 11 is an engine mounted on the front of the vehicle,
Reference numeral 12 denotes an automatic transmission connected to an output shaft of the engine 11, and the automatic transmission 12 includes a torque converter 12A having an input shaft connected to the output shaft of the engine 11, and an output shaft of the torque converter 12A. The transmission gear mechanism 12B is generally constituted by a connected planetary gear reduction mechanism and the like. The output shaft of the transmission gear mechanism 12B is a propeller shaft 13
The front end side of the propeller shaft 13 is connected to rear wheels 15, 15 serving as drive wheels via a differential gear 14, and the like. 16, 16 are front wheels to be driven wheels, 17 and 18 are front wheel speed sensors for detecting the rotation speed of each front wheel 16,
The front wheel speed sensors 17 and 18 detect left and right front wheel speeds V _l and V _r , respectively, and output the detected front wheel speeds to a control unit 29, which will be described later, to obtain a vehicle speed V _B. Is detected.

19 shows a wheel speed sensor after detecting the rotational speed of the propeller shaft 13 as a rotational speed of each rear wheel 15, rear wheel speed sensor 19 to the control unit 29 the rotation speed of each rear wheel 15 as a wheel speed V _W Output. Reference numeral 20 denotes a torque sensor as a torque detecting means provided between the automatic transmission 12 and the propeller shaft 13 and the like. The torque sensor 20 is disposed between the output shaft of the automatic transmission 12 and each rear wheel 15. The torsional moment acting on 13
So that the detected as driving torque T _S of the vehicle, and outputs it to the control unit 29 by.

21 is an input rotational speed sensor as an input rotational speed detecting means for detecting the input side speed N _E of the torque converter 12A,
Reference numeral 22 denotes an output rotation speed sensor as output rotation speed detection means for detecting the output rotation speed _NT of the torque converter 12A,
The rotation speed sensors 21 and 22 output the respective detection signals to the control unit 29, and determine the speed ratio e of the torque converter 12A based on the respective rotation speeds N _E and _NT. Is calculated. Reference numeral 23 denotes a speed ratio sensor as a speed ratio detecting means for detecting a speed ratio of the speed change gear mechanism 12B of the automatic transmission 12, and the speed ratio sensor 23 outputs a speed ratio signal to the control unit 29, to set the gear ratio G _R as the gear ratio by the shift gear mechanism 12B.

Next, in FIG. 2, reference numeral 24 denotes a throttle sensor for detecting a valve opening θ of a throttle valve (not shown). The throttle sensor 24 is attached to a throttle valve provided in the intake passage of the engine 11. When the throttle valve is opened and closed by operating an accelerator pedal (not shown), the valve opening θ is detected, and a detection signal is output to the control unit 29. And
This throttle valve has an engine
The intake air amount of the engine 11 is controlled, and the engine 11
Output is increased or decreased. Also the engine
A subthrottle valve (not shown) is provided in the intake passage 11 in series with the throttle valve.

Reference numeral 25 denotes a throttle actuator for opening and closing the sub-throttle valve. The throttle actuator 25 closes the sub-throttle valve when the vehicle slips to limit the amount of intake air. , The intake air amount is controlled according to the valve opening degree θ of the throttle valve. And the throttle actuator
Reference numeral 25 denotes an electric motor for opening and closing the sub-throttle valve based on a control signal from the control unit 29. Reference numeral 26 denotes an ignition device that outputs an ignition signal to the engine 11.The ignition device 26 changes the ignition timing of the engine 11 when a vehicle slip occurs, based on a control signal from the control unit 29, and changes the output of the engine 11. It is lowered together with the throttle actuator 25.

Reference numeral 27 denotes a brake control device for controlling the braking force of the vehicle. The brake control device 27 applies a brake to a brake cylinder (not shown) provided on each of the rear wheels 15 and each of the front wheels 16 when, for example, a vehicle slips. By supplying the hydraulic pressure and applying a braking force to each rear wheel 15 and each front wheel 16, the driving force of the vehicle by the engine 11 is forcibly reduced. Reference numeral 28 denotes a vehicle height sensor as a vehicle height detector provided between the vehicle body side and the axle side of the vehicle, and the vehicle height sensor 28 changes according to the load weight of the vehicle, the movement of the center of gravity during traveling, and the like. By detecting the vehicle height on the wheel 15 side or the front wheel 16 side and outputting the detected vehicle height signal H to the control unit 29, the control unit 29 calculates the rear wheel load W and the like acting on each rear wheel 15. It has become.

Further, reference numeral 29 denotes a control unit constituted by a microcomputer or the like, and the control unit 29 has front wheels speed sensors 17, 18, a rear wheel speed sensor 19, a torque sensor 20, an input speed sensor 21, an output speed A number sensor 22, a speed ratio sensor 23, a throttle sensor 24, a vehicle height sensor 28, and the like are connected, and a throttle actuator 25, an ignition device 26, a brake control device 27, and the like are connected to an output side. Then, the control unit 29
Stores the program and the like shown in FIG. 3 in its storage circuit, and performs processing for controlling the driving force of the vehicle by the engine 11 and the like. The storage circuit of the control unit 29 stores a set value S ₀ of the slip ratio S and a speed ratio e of the torque converter 12A shown in FIG.
And a characteristic map of the input torque capacity coefficient τ with respect to the speed ratio e shown in FIG. 5, and a torque difference T _d between the output shaft torque Tθ and the driving torque T _S.
Is stored, and a slip occurrence limit value of the driving torque with respect to the friction coefficient μ of the road surface is stored.

The vehicle driving force control device according to the present embodiment has the above-described configuration. Next, the output control process of the engine 11 by the control unit 29 will be described with reference to FIG.

First, when the processing operation is started, reads the vehicle speed V _B and the wheel speed V _W from the front wheel speed sensor 17, 18 and Kowasoku sensor 19 in step 1, a slip ratio S according to the equation (1) Step 2 operation I do. Then, the slip ratio S is determined whether exceeds the set value S ₀ moves to step 3,
When the determination is "NO", the process proceeds to step 4, where the input speed sensor 21 and the output speed sensor 22 of the torque converter 12A are
Input, output rpm N _E from reads the N _T, Step 5
The speed ratio e of the torque converter 12A is obtained by the above equation (3).
Is calculated.

Then, the process proceeds to step 6 where the torque converter 12 is obtained from the characteristic maps shown in FIGS.
Reading the torque ratio of A epsilon and input torque capacity coefficient tau respectively, the input torque T _E of the torque converter 12A in step 7, the computed as ^{_{T E = τ × N E 2}} ...... (4), the output torque T _T Is calculated as T _T = ε × τ × N _E ² (5).

Next, at step 8, the speed ratio sensor 23 of the automatic transmission 12
, The program proceeds to step 9 to determine whether or not the automatic transmission 12 is in the middle of shifting. When the determination is "NO", the transmission gear mechanism 12B is switched to the desired gear ratio, and the engine 11 propeller shaft 13 output via the automatic transmission 12, because they are transmitted as driving force to the rear wheels 15, reads the gear ratio G _R of the transmission gear mechanism 12B on the basis of the gear ratio signal shifts to step 10 , the output shaft torque T.theta of the automatic transmission 12 and an output torque T _T and the gear ratio G _R by the equation (5) in step 11, as _{Tθ = ε × τ × N E} 2 × G R ...... (6) Calculate.

Then, in step 12, the driving torque T _S as the actual torque on the output shaft side of the automatic transmission 12 is determined by a torque sensor.
20 and the process proceeds to step 13 where the torque difference T _d between the output shaft torque Tθ which is the calculated value and the drive torque T _S which is the detected value.
And was calculated as _{T d = Tθ-T S ......} (7), the absolute value of the torque difference T _d at step 14 | T _d | is equal to or greater than the set value alpha. When it is determined to be “NO” in step 14, the torque difference T _d , that is, the sixth
The drive torque T _S and the output shaft torque T indicated by characteristic lines 3 and 4 in the figure.
the difference between θ is, for example, because it is time t ₁ earlier relatively small state as can be judged that the rear wheels 15 are not slipping (idling) on the road surface, and then proceeds to step 15.

Next, at step 15, the vehicle height signal H is read from the vehicle height sensor 28, and the routine proceeds to step 16 where each rear wheel is determined based on the vehicle height signal H.
The rear wheel load W acting on 15 is calculated. And step
Moving to 17, the friction coefficient μ of the road surface, Where, T _S : drive torque by torque sensor i _f : final gear ratio by differential gear r: rear wheel tire radius W: rear wheel load, and the calculated road surface friction coefficient μ at that time is stored in step 18. The data is written and stored in the RAM or the like in the area 29A while being sequentially updated. Then, in step 19, a release signal for releasing the driving force control is continuously output, for example, the output of the engine 11 is controlled in accordance with the valve opening degree θ of the throttle valve, and the process proceeds to step 20 to return.
The process from step 1 is continued.

Further, when it is determined as "YES" in the step 14, the torque difference T _d becomes larger than the predetermined set value α, for example, the sixth after the time t ₁ as characteristic lines 3 and 4 shown in the figure, the rear wheel 15 Is starting to slip on the road,
In step 21, the latest friction coefficient μ stored in the storage area 29A is read, and in step 22, the driving force of the vehicle by the engine 11 is determined based on the friction coefficient μ, for example, slip (slip).
A control signal is output to at least one of the throttle actuator 25, the ignition device 26, and the brake control device 27 in order to lower the generation limit value, for example, when the sub-throttle valve is closed by the throttle actuator 25, Thus, the intake air amount of the engine 11 is limited, the drive torque T _{S and the} like are reduced to the limit value of the occurrence of slip with respect to the friction coefficient μ of the road surface, and so-called traction control is performed.

And, if it is determined "YES" in step 3,
Slip ratio S becomes larger than the set value S _0, since the state in which the slip of the vehicle is occurring, performs driving force control of the vehicle based on the latest friction coefficient μ shifts to step 21. When it is determined "YES" in step 9, the automatic transmission 12 is in the middle of shifting, and the driving torque T _S may fluctuate greatly. Therefore, the process proceeds to step 19 to output a hold or release signal. The driving force control is maintained during the driving force control, and otherwise, the driving force control is continuously released, thereby preventing the driving force control from being performed erroneously and returning to step 20. Then, by repeating the processing of steps 1 to 22, traction control is performed so that the vehicle can be smoothly accelerated by the output of the engine 11 while the slip of the vehicle is avoided as quickly as possible.

Therefore, according to this embodiment, in a vehicle equipped with the automatic transmission 12, the output shaft torque Tθ of the automatic transmission 12 is calculated, and the torque difference between the output shaft torque Tθ and the driving torque T _S by the torque sensor 20 is calculated. _Td is calculated, and the driving force control is determined based on whether the torque difference _Td is larger than a set value α,
Since the driving force control is performed based on the friction coefficient μ of the road surface calculated and stored before the occurrence of the slip, the slip ratio S
Before the vehicle reaches the set value S ₀ , it is possible to quickly determine the occurrence of vehicle slip based on the torque difference T _d with high responsiveness, effectively avoid vehicle slip, and add the maximum that can be added. Torque (limit value) from engine 11 to each rear wheel
15 and various effects such as being able to secure good acceleration even on a low μ road surface such as a snowy road, and to improve safety during starting and running.

In the embodiment, in the program shown in FIG. 3, step 7 shows a specific example of the output torque calculating means which is a constituent element of the present invention, and step 11 shows a specific example of the output shaft torque calculating means. Step 13 is a specific example of the torque difference calculating means, step 14 is a specific example of the torque difference determining means, and step 22 is a specific example of the driving force control means.

In the above-described embodiment, the output of the engine 11 is described as being reduced by the throttle actuator 25, for example. Alternatively, the output may be reduced by restricting the fuel injection amount from the injector when a slip occurs, for example. You may do so.

Further, in the above-described embodiment, the description has been given by taking as an example a rear-wheel drive vehicle equipped with an automatic transmission as a vehicle, but the present invention is not limited to this. For example, a front-wheel drive vehicle equipped with an automatic transmission or a four-wheel drive It can also be used as a driving force control device for a vehicle such as a vehicle equipped with various automatic transmissions.

〔The invention's effect〕

As described in detail above, according to the present invention, the output shaft torque of the automatic transmission is calculated, and the driving force of the vehicle by the engine is controlled based on the torque difference between the output shaft torque and the driving torque. Before the slip ratio reaches a predetermined set value, it is possible to quickly determine the time of occurrence of the slip and quickly reduce the driving force, thereby effectively avoiding the slip of the vehicle and improving the acceleration performance. Thus, various effects can be achieved, such as improving the safety of the vehicle when starting and running, and improving the responsiveness of the driving force control.

[Brief description of the drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a block diagram of a rear-wheel drive vehicle equipped with an automatic transmission, FIG. 2 is a control block diagram, and FIG. Flow chart shown, fourth
FIG. 5 is an explanatory diagram showing a characteristic map of a torque ratio stored in a storage area, FIG. 5 is an explanatory diagram showing a characteristic map of an input torque capacity coefficient stored in a storage area, and FIG. FIG. 4 is a characteristic diagram of a vehicle speed, a wheel speed, a valve opening, a driving torque, and the like. 11 ... Engine, 12 ... Automatic transmission, 12A ... Torque converter, 12B ... Transmission gear mechanism, 13 ... Propeller shaft, 15 ... Rear wheel, 16 ... Front wheel, 17,18 ... Front wheel speed sensor , 19 ... Rear wheel speed sensor, 20 ... Torque sensor, 25 ...
Throttle actuator, 29 ...... control unit, V _B ...... vehicle speed, V _W ...... wheel speed, S ...... slip ratio, T _T ...... output torque, T.theta ...... output shaft torque, T _S ......
Drive torque, T _d …… Torque difference.

Claims (2)

(57) [Claims] 1. A vehicle driving force control device for calculating a slip ratio of driving wheels based on a vehicle body speed and a wheel speed of a vehicle and controlling a driving force of the vehicle by an engine based on the slip ratio. Automatic transmission having a torque converter and a transmission gear mechanism connected to an output shaft of the automatic transmission, a transmission ratio detecting means for detecting a transmission ratio of the transmission gear mechanism of the automatic transmission, and an input-side rotational speed of the torque converter. Input speed detecting means for detecting the output speed of the torque converter, output speed detecting means for detecting the output speed of the torque converter, torque detecting means for detecting the driving torque of the vehicle on the output shaft side of the automatic transmission, Output torque calculating means for calculating the output torque of the torque converter based on detection signals from the input rotational speed detecting means and the output rotational speed detecting means; Output shaft torque calculating means for calculating the output shaft torque of the automatic transmission based on the output torque calculated by the torque calculating means and the speed ratio from the speed ratio detecting means; and the output shaft calculated by the output shaft torque calculating means. Torque difference calculating means for calculating the difference between the torque and the driving torque detected by the torque detecting means; and torque difference determining means for determining whether the torque difference by the torque difference calculating means is greater than a predetermined set value. And a driving force control means for reducing the driving force of the vehicle by the engine when the torque difference determination means determines that the torque difference is larger than a set value. apparatus. 2. The vehicle driving force control device according to claim 1, wherein the driving force control by the driving force control means is held or released when the automatic transmission is in a shift state.