JP3134532B2 - Vehicle driving force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle driving force control capable of realizing both drivability intended by a driver and ensuring running stability when the driver operates an accelerator. It concerns the device.

[0002]

2. Description of the Related Art As a conventional example of a vehicle drive control device for performing drive torque control, which variably controls the drive torque supplied to the drive wheel when a drive slip occurs in the drive wheel according to the drive slip state, For example, JP-A-63-3183
There is one disclosed in Japanese Patent Publication No. 0. In this conventional example, the engine drive torque is variably controlled so that the drive slip state becomes a slip target value (reference value) by using an accelerator operation amount (substituted by a throttle opening) as a parameter. The drive slip is eliminated. At this time, the slip target value is increased as the absolute value of the accelerator operation amount, which is a parameter indicating the driver's intention to accelerate, is increased so that the drivability intended by the driver is realized.

[0003]

However, in the above-mentioned conventional vehicle driving force control device, since the control for simply increasing the slip target value as the accelerator operation amount is increased is performed, the following inconveniences occur. Invite. First
In addition, when the driver performs a rapid accelerator depressing operation, the slip target value increases rapidly and a large slip is allowed, so that the driving stability is secured against the driver's careless accelerator operation. That is, the original function of the driving force control device is impaired.

Second, whether the vehicle is in a turning state or a straight running state is simply determined based on the accelerator operation amount, and the fact that the accelerator operation amount differs depending on the road surface condition, vehicle speed, turning radius, and the like is not taken into consideration. The slip target value changes with the same characteristics between the state and the straight running state. For example, during a high-G turn with a large accelerator operation amount, the slip target value becomes large in the same manner as when exiting a corner despite turning. As a result, a large slip is allowed, and as a result, the essential function of the driving force control device for securing the turning stability is impaired.

According to the present invention, when a slip reference value is controlled in accordance with an accelerator operation amount indicating a driver's intention to accelerate,
By limiting the slip reference value so that it does not increase sharply, the above-mentioned problem is solved by realizing both drivability intended by the driver and ensuring traveling stability when the driver operates the accelerator. The purpose is to do.

[0006]

For this purpose, a driving force control apparatus for a vehicle according to the present invention comprises a driving slip detecting device for detecting a driving slip state of a driving wheel as shown in FIG. A vehicle comprising: a detection unit; a slip reference value setting unit that sets a slip reference value of the drive wheel; and a drive torque control unit that performs drive torque control based on the detected drive slip state and the set slip reference value. An accelerator operation detecting means for detecting an increment of the accelerator opening at the time of accelerator operation, and a control signal formed by multiplying an accelerator opening increment signal output by the accelerator operation detecting means by at least a predetermined gain. When the slip reference value is corrected by the slip reference value correction means and the slip reference value correction means, Serial accelerator opening increment signal, the predetermined gain, limits at least one of said control signal, and characterized by providing a signal limiting means.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, there is provided a straight turning judgment means for judging whether the vehicle is in a straight running state or a turning state, and the vehicle is controlled in accordance with an output signal of the straight turning judgment means. The signal limiting means is activated when it is determined that the vehicle is turning.

[0008]

According to the first aspect of the present invention, the driving slip state detected by the driving slip detecting means and the slip reference value set by the slip reference value setting means are determined based on the slip condition.
When the drive torque control means performs drive torque control, the slip reference value correction means sets the slip reference value in accordance with a control signal formed by multiplying an accelerator opening increment signal output by the accelerator operation detection means by at least a predetermined gain. When the signal limiting means corrects the slip reference value by the slip reference value correcting means, the signal limiting means limits at least one of the accelerator opening increment signal, the predetermined gain, and the control signal. When the accelerator is inadvertently operated by the user (for example, when the driver steps on the vehicle suddenly), the increase in the slip reference value is limited, so that a problem that running stability is impaired can be prevented.

According to the second aspect of the present invention, when the vehicle is determined to be in a turning state in accordance with an output signal of a straight turning determining means for determining whether the vehicle is in a straight running state or a turning state during the control. Only when the signal limiting means is operated, the increase in the slip reference value is limited when the driver inadvertently operates the accelerator during turning of the vehicle, so that running stability during turning can be ensured.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows a first embodiment of the vehicle driving force control device according to the present invention.
It is a figure showing composition of an example, in which 1L and 1R show a left front wheel, a right front wheel, 2L and 2R show a left rear wheel, a right rear wheel, and 3 show an engine. This vehicle is a rear-wheel drive vehicle in which rear wheels 2L and 2R, which are drive wheels, are driven by an engine 3.
Wheel rotation sensors 4, 5, 6, and 7 are provided near L, 1R, 2L, and 2R, respectively (note that the vehicle may be an all-wheel drive vehicle).

The wheel rotation sensors 4 to 7 detect the rotation speed of each wheel as a pulse signal having a frequency corresponding to the rotation speed, and obtain the obtained rotation speeds VFL, VFR, VFR,
Pulse signals having a frequency corresponding to VRL and VRR are input to the F / V converter 9 of the driving force control unit 8. The driving force control unit 8 includes an F / V converter 9, an A / D converter 10, and a CPU 11, and the F / V converter 9
The A / D converter 10 converts the input signals from the wheel sensors 4 to 7 into voltages and inputs the signals to the A / D converter 10. The A / D converter 10 converts the input signals into digital signals and inputs them to the CPU 11.
The CPU 11 uses, for example, a microcomputer.

In this embodiment, an accelerator opening sensor 14 is provided as accelerator operation detecting means for detecting an accelerator operation state (accelerator operation amount), and an output signal of the accelerator opening sensor L is input to the A / D converter 10. I do.

The CPU 11 executes the control programs shown in FIGS. 3 to 9 based on the inputted wheel rotation speeds (wheel speeds) VFL, VFR, VRL, VRR and the accelerator opening (operation amount) L. The slip reference value used when performing the drive torque control is variably controlled according to the accelerator operation amount. The first embodiment is based on an engine control system that adjusts the torque applied to the driving wheels by adjusting the driving torque itself of the engine. The CPU 11 sends a fuel supply cut signal FC to the fuel supply control unit 12. The injection pulse IP output from the fuel supply control unit 12 to each of the cylinders 13-1 to 13-6 of the engine is cut off by this signal FC, and the fuel is cut off.

FIG. 3 is repeatedly executed by a non-illustrated operation system by a periodic interruption at a predetermined cycle.
First, in step 101, the rotational speeds VFL, VFR of the left and right front wheels as driven wheels and the rotational speeds VRL, VRR of the left and right rear wheels as drive wheels are read from the corresponding wheel rotation sensors 4 to 7, respectively. In step 102, the average rotational speed VF of the front wheel (follower wheel) is calculated as VF = (VFL +
VFR) / 2, and at step 103, the average rotational speed VR of the rear wheels (drive wheels) is calculated as VR = (VRL + VRR) /
2, and in step 104, the drive slip amount S is calculated as
S = VR−VF. In the control program shown in FIG. 3, the CPU 11 functions as a drive slip detecting unit.

FIG. 4 is executed after step 104.
In step 111 of the control program, the slip peak value Sp is read. In this read,
In the first control, the slip S obtained in step 104 becomes the slip peak value Sp as it is. After the second control, the slip peak value is updated according to the determination in the next step 112. That is, when the current slip S exceeds the currently stored slip peak value Sp, such as when a drive slip occurs, the determination in the next step 112 is YES of S> Sp, and the step 113 is selected. In step 113, the slip peak value Sp is updated to the slip S. If S is equal to or smaller than Sp, step 113 is skipped and the slip peak value is not updated.

In the next step 114, the peak of slip is determined based on whether S <Sp-α. The determination of the peak of the slip is that the slip peak value Sp is continuously updated by executing the above steps 112 to 113 while the slip S continues to increase when the drive slip occurs, but after the slip S starts to decrease, the Sp Is fixed without being updated, it is determined that the slip has passed the peak when the slip S at a certain point falls below the slip peak value Sp by the predetermined value α or more, and it is determined that the slip has passed the peak. In step 115, a peak determination flag PF is set in step 115 (PF = 1). The state of PF = 1 in the peak determination flag obtained in this manner indicates that the torque reduction control of the engine has been performed due to the occurrence of the drive slip, and the slip has shifted to the convergence direction. Note that the predetermined value α is determined based on a safety factor that prevents erroneous peak determination from being performed due to sensor signal noise or the like.

FIG. 5 is executed after step 115.
Is to determine whether or not to reset the peak determination flag. First, at step 121, the torque down instruction amount TD determined as described in detail later is read. In the next step 122, it is determined whether the torque down instruction amount TD is 0 or not. If YES in this determination, that is, if the torque-down instruction amount TD is 0 and the drive torque reduction control is not being performed, it is determined that the control has ended, and the peak determination flag is reset in step 123 (PF = 0).

FIG. 6 is executed after step 123.
In step 131 of the control program,
The front wheel average rotational speed VF (vehicle speed V
Is read), and the left and right front wheels are rotated in step 132.
Number difference ΔVF_RLTo ΔVF_RL= | VFR-VFL |
calculate. In the next step 133, the reciprocal of the turning radius R is used.
Let a certain turning curvature ρ be ρ = (ΔVF _RL/ T_r) / VF
(However, T_rIs the tread of the front wheel),
In step 134, the turning curvature ρ is set to a predetermined value ρ₀ Is greater than
It is determined whether or not it is. In this determination, ρ> ρ₀ YE
If S, it is determined that the vehicle is turning and control proceeds to step 135.
First, a turning judgment flag CFc is set (CF = 1), and ρ
≤ρ₀ If NO, it is determined that the vehicle is traveling straight and control is
Step 136 is performed to reset the turning judgment flag CF (C
F = 0). In the control program of FIG.
U11 functions as a straight turning judgment means.

Steps 135 and 13 of the control program shown in FIG.
Steps of the control program of FIG. 7 executed after 6
At 141, the state of the peak determination flag PF is checked. Here, if YES, that is, if it is determined that the slip has passed the peak and has converged at PF = 1, the control proceeds to step 142 and thereafter to correct a slip reference value described later, and NO, that is, PF = If it is determined at 0 that the slip has not passed the peak, or if the drive torque control is not being performed, the control proceeds to step 143 to clear a slip reference value correction amount SL described later (SL = 0).

In step 142, using the accelerator opening L read from the accelerator opening sensor, the accelerator opening increment (accelerator depressing amount) ΔL with respect to the previous sampling is determined by ΔL (n) = L (n) − It is calculated by L (n-1). Here, ΔL is an accelerator opening increment signal. In the next step 144, the turning judgment flag CF is checked. Here, if CF = 1 is YES (at the time of turning state determination), a limiter is applied to the increment ΔL of the accelerator opening by ΔL = Min (ΔL, ΔL ₀ ) in step 145, and then the gain KL is set to KL in step 146. = KLc, and if CF = 0 is NO (at the time of determining the straight running state), the gain KL is determined to be KL = KLs in step 147. In the above, ΔL ₀ is the upper limit value of the accelerator release speed allowed during turning, and the gain KLc at the time of turning is the gain K at the time of straight traveling.
It shall be set to a value smaller than Ls.

In step 148 following steps 146 and 147, the increment ΔSL of the slip reference value is calculated as follows: ΔSL = KL · ΔL
It is calculated by: Here, the increment ΔSL of the slip reference value
Is formed by multiplying the accelerator opening increment signal ΔL by at least the gain KL, and is a control signal used for the following slip reference value correction. In the next step 149, the slip reference value correction amount SL is calculated from SL (n) = SL (n-1) + ΔSL (n). Further, in the next step 170, the slip reference value correction amount SL is set to SL = so that the slip reference value correction amount SL always becomes a value of 0 or more (so as not to be negative).
Set by Max (SL, 0). In the control program of FIG. 7, the CPU 11 functions as accelerator operation detecting means and slip reference value correcting means.
As described later, it also functions as a signal limiting unit.

In the control program shown in FIG. 8, which is executed after step 150 of the control program shown in FIG. 7, the average rotational speed VF of the front wheels is read in step 151. Next steps
At 152, the initial value S of the slip reference value is obtained by looking up the map of FIG. 10 based on this VF.
* Determine ₀ . At step 153, the previously determined slip reference value correction amount SL is read, and at step 154, the slip reference value S * is calculated from S * = S * ₀ + SL. At this time, the characteristic of changing the slip reference value S * according to the accelerator opening changes according to the gain determined at step 146 or step 147, in other words, according to the turning state / straight traveling state determination. In the control program of FIG. 8, the CPU 11 functions as a slip reference value setting unit.

In step 161 of the control program shown in FIG. 9, which is executed after step 154 of the control program shown in FIG. 8, the current drive slip amount S is read.
In step 162, the previously obtained slip reference value S * is read, and in step 163, the two are compared. Here, if S> S * YES, the routine proceeds to step 164, where it is determined whether the torque down instruction amount TD is the maximum value TDmax. If S ≦ S * NO, the routine proceeds to step 165, where the torque down instruction amount TD Is determined to be 0 or not.

Since the determination in the above steps 164 and 165 is NO when TD takes a value between the upper limit value and the lower limit value, in that case, T is set in the next steps 166 and 167, respectively.
D is incremented (TD = TD + 1) and decremented (TD = TD-1). In the case of YES, since the upper limit value or the lower limit value has already been reached and increment and decrement cannot be performed, respectively, step 16
6, skip 167. Then, in step 168, the CPU 11 outputs the fuel supply cut signal FC corresponding to the torque down instruction amount TD to the fuel supply control unit 12. In the control program shown in FIG. 9, the CPU 11 functions as a driving torque control unit.

In the first embodiment, the trade-off between the realization of the drivability intended by the driver and the assurance of the driving stability when the driver operates the accelerator is eliminated in the following manner. . That is, when entering the corner, FIG.
The turning curvature ρ obtained in step 133 of
Since the turning determination flag CF is set (CF = 1) in step 135 along with the determination in step 134 being YES, if the determination in step 141 in FIG. 7 is YES, the control proceeds to YES in step 141. 142-144 YES-145-146
And will proceed.

Therefore, when the control program of FIGS. 7 and 8 is executed to increase the slip reference value increment ΔSL with the gain KL in accordance with the accelerator opening increment ΔL as shown in FIG. , increment [Delta] L of the accelerator opening as shown in FIG. 5 (b) is limited to a predetermined value or less [Delta] L ₀ by the execution of step 145, also the gain KL as shown in FIG. 3 (c) is straight through execution of step 146 Time gain KLS
Since it is limited to a smaller value of KLC, the above step 14
In steps 5 and 146, the CPU 11 functions as signal limiting means. As a result, an increase in the slip reference value during a careless accelerator operation by the driver during turning of the vehicle is limited, and traveling stability during turning is ensured.

On the other hand, when the vehicle escapes from the corner, the steps shown in FIG.
Since the turning curvature ρ obtained in 133 decreases and the determination in step 134 becomes NO, the turning determination flag CF is reset (CF = 0) in step 135, so that the determination in step 141 in FIG. If so, control is passed to step 141
YES-142 -144 and NO-147
By executing the control programs of FIGS. 7 and 8, FIG.
As shown in (a), when increasing the slip reference value increment ΔSL with the gain KL in accordance with the accelerator opening increment ΔL, the execution of step 147 causes the gain KL to turn as shown in FIG. The value of KLS is larger than the gain KLC at the time. As a result, the slip reference value increases as the accelerator operation amount increases when exiting a corner, and the drivability intended by the driver is realized.

FIG. 12 is a flowchart showing a control program of a main part of the second embodiment of the vehicle driving force control apparatus according to the present invention. The second embodiment has the same configuration as the first embodiment except that the control program of FIG. 12 is used instead of the control program of FIG. 7 of the first embodiment. FIG. 12 is executed after steps 135 and 136 of the control program of FIG.
The control program of Step 14 is executed between Step NO and Step 147 of the control program of FIG.
5a is inserted, and the rest is exactly the same as FIG.

In step 145a, the control proceeds when the straight traveling state is determined to be NO. In step 145a, similarly to step 145 described above, the limiter is set to ΔL = Min (ΔL, ΔL ₁ ) for the increment ΔL of the accelerator opening. (However, ΔL ₁ is the upper limit of the accelerator release speed allowed while traveling straight, where ΔL ₁ > ΔL ₀ ).
In 145, 146 and 145a, the CPU 11 functions as a signal limiting means.

In the second embodiment, the above steps
With the addition of 145a, a limiter is applied to the increment ΔL of the accelerator opening regardless of whether the vehicle is in a straight running state or a turning state (in the first embodiment, the limiter is applied only when the turning state is determined). Since the upper limit value ΔL ₀ of the accelerator opening speed allowed is set smaller than the upper limit value ΔL ₁ during straight traveling, the limiter is more strongly applied during turning,
When the driver inadvertently operates the accelerator (for example, sudden depression), the increase in the slip reference value is limited, and a problem that running stability is impaired is prevented.

In each of the above-described embodiments, the signal limiting means uses the characteristics shown in FIGS. 11 (b) and 11 (c) to increase the accelerator opening ΔL,
Although the gain KL is limited, the upper limit of the increment ΔSL of the slip reference value may be limited instead, as shown in FIG. In this case, the limit amount at the time of turning shown by the dotted line is made smaller than the limit amount at the time of straight traveling shown by the solid line. Further, in each of the above embodiments, the front wheel average rotation speed VF, the left and right front wheel rotation speed difference ΔVF _RL and the tread Tr are used to calculate the turning curvature of the vehicle, but a yaw rate may be used instead. , Vehicle turning /
Turning curvature ρ (turning radius R) as a parameter for determining straight ahead
Is used, but the yaw rate of the vehicle, the changing speed of each of the above physical quantities, and the like may be used instead.

Further, in each of the above embodiments, the drive torque control by the fuel supply cut is adopted as the traction control. However, the present invention is not limited to this. For example, a throttle opening for electrically controlling the throttle valve of the engine is employed. Degree control, engine ignition timing control, or brake control for directly applying pressure to a wheel cylinder may be used.

[0033]

As described above, the vehicle driving force control apparatus according to the present invention, when controlling the slip reference value in accordance with the accelerator operation amount indicating the driver's intention to accelerate, increases the slip reference value rapidly. Since the restriction is made so as not to increase the slip reference value when the driver carelessly operates the accelerator (for example, sudden depression), it is possible to prevent a problem that running stability is impaired. Further, by performing the above-described limitation only when the vehicle is determined to be in a turning state, an increase in the slip reference value is limited at the time of inadvertent accelerator operation of the driver during the turning of the vehicle, so that the increase in the slip reference value during the turning is restricted. Driving stability can be ensured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a diagram showing a configuration of a first embodiment of a vehicle driving force control device of the present invention.

FIG. 3 is a flowchart showing a control program for calculating a drive slip amount in the same example.

FIG. 4 is a flowchart showing a control program for updating a slip peak value and setting a peak determination flag in the same example.

FIG. 5 is a flowchart showing a control program for resetting a peak determination flag in the same example.

FIG. 6 is a flowchart showing a control program for determining a straight traveling state / turning state in the same example.

FIG. 7 is a flowchart showing a control program for setting a slip reference value correction amount in the same example.

FIG. 8 is a flowchart showing a control program for setting a slip reference value in the same example.

FIG. 9 is a flowchart showing a control program of drive torque control in the same example.

FIG. 10 is a diagram illustrating a map used for setting an initial value of a slip reference value in the same example.

FIG. 11A is a diagram for explaining the operation of the same example. (b) is a figure for explaining the operation of the example. (c)
FIG. 4 is a diagram for explaining the operation of the example. (d) is a figure for demonstrating the effect | action of the same example.

FIG. 12 is a flowchart showing a control program of a main part of a second embodiment of the vehicle driving force control device of the present invention.

[Explanation of symbols]

1L, 1R Front wheel (driven wheel) 2L, 2R Rear wheel (drive wheel) 3 Engine 4-7 Wheel rotation sensor 11 CPU (drive slip detection means, slip reference value setting means, drive torque control means, slip reference value correction means, Signal limiting means) 12 fuel supply control unit 13-1 to 13-6 cylinder 14 accelerator opening sensor (accelerator operation detecting means)

Continuation of the front page (56) References JP-A-3-156135 (JP, A) JP-A-4-59457 (JP, A) JP-A-63-18144 (JP, A) JP-A-3-258938 (JP) JP-A-4-123938 (JP, A) JP-A-3-227763 (JP, A) JP-A-4-59437 (JP, A) JP-A-2-227337 (JP, A) JP 64-83830 (JP, A) JP-A-63-31830 (JP, A) JP-A-3-281483 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 29/02 311

Claims (2)

(57) [Claims] 1. A drive slip detection means for detecting a drive slip state of a drive wheel, a slip reference value setting means for setting a slip reference value of the drive wheel, and a drive slip state based on the detected drive slip state and a set slip reference value. A driving force control device for a vehicle, comprising: a driving torque control unit that performs driving torque control; an accelerator operation detecting unit that detects an increment of an accelerator opening when an accelerator is operated; and an accelerator opening output by the accelerator operation detecting unit. A slip reference value correcting unit that corrects the slip reference value according to a control signal formed by multiplying the degree increment signal by at least a predetermined gain; and correcting the slip reference value by the slip reference value correcting unit. Signal limiting means for limiting at least one of the opening increment signal, the predetermined gain, and the control signal A driving force control device for a vehicle, comprising: 2. The vehicle according to claim 1, further comprising: a straight-turn determining unit configured to determine whether the vehicle is in a straight-running state or a turning state, and activating the signal limiting unit when the vehicle is determined to be in a turning state in accordance with an output signal of the straight-turning determining unit. The driving force control device for a vehicle according to claim 1, wherein the driving force control device is configured to control the driving force.