JP2006220011A - Traction control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a traction control device capable of suppressing excess and delay of engine traction control. <P>SOLUTION: This traction control device 20 is provided with an engine traction control means 22 which determines that slip occurs when a difference between an average value of a plurality of wheel speeds detected by wheel speed sensors 10 arranged in all drive wheels and an estimated vehicle body speed calculated by an estimated vehicle body speed calculating means 21 exceeds a predetermined threshold value and lowers engine torque. The traction control device 20 is further provided with a slip wheel number calculating means 23 for calculating the number of slipped wheels by determining whether or not a difference between each wheel speed of each drive wheel and the estimated vehicle body speed exceeds a predetermined value. The engine traction control means 22 is constituted so as to largely lower the engine torque as the number of wheels calculated by the slip wheel number calculating means 23 increases. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a traction control device that performs engine traction control.

  In recent years, traction control that performs engine traction control, such as lowering the relative speed between the slipping drive wheel and the ground (reducing the slip amount) and restoring the grip force by lowering the engine output when the drive wheel of the vehicle slips. The device is known. As such a traction control device, there is a conventional one as shown below.

  The first technique is a traction control device for a two-wheel drive vehicle, and when the larger slip amount of the slip amounts of the drive wheels (left and right) exceeds a predetermined threshold, It is determined that the vehicle has slipped, and engine traction control is started (see Patent Document 1). Note that the engine traction control in this technique is a control in which the engine output is reduced at a predetermined reduction rate that is determined in advance, and therefore, when the drive wheel that is judged to have slipped is one wheel or two wheels. The control amount (decrease in engine output) does not change.

  Further, as a technique similar to the first technique, when the average wheel speed (right and left average wheel speed) of the drive wheels as shown in FIG. 5 becomes equal to or higher than a predetermined threshold (estimated vehicle body speed + predetermined value α). In some cases, it is determined that the drive wheel has slipped and engine traction control is started. In this technique as well, for example, even when only the left wheel is sliding (arrow 1) or when all the two wheels are sliding (arrow 2), the average left and right wheel speed is predetermined. When the threshold value is exceeded, the engine torque (engine output) is reduced at a predetermined rate of decrease (arrows 3 and 4).

  The second technique is a traction control device for a four-wheel drive vehicle, and when the slipped wheels are two or less, the driving force is slipped to the front and rear wheels by the torque split controller (from the slipped side). The control is performed so that the slip state is removed from the slip state, and when there are three or more slipped wheels, engine traction control is started (see Patent Document 2). Note that the engine traction control in this technique is also a control in which the engine output is reduced at a predetermined reduction rate determined in advance, as in the technique described above, and therefore, when there are three drive wheels that are judged to have slipped. That is, the control amount does not change between the four wheels.

Japanese Patent Laid-Open No. 5-8666 JP-A-1-111530

  However, in the first technique described above and the technique shown in FIG. 5, since there is no difference in control between the one wheel and the two wheels that are slipping, for example, the engine output reduction rate is a value suitable for one wheel slip. When set to an intermediate value suitable for two-wheel slip, there is a problem that engine traction control becomes excessive (engine torque is too low) in the case of one-wheel slip, and in the case of two-wheel slip There has been a problem that the engine traction control is delayed (the grip force of the wheel with the smaller slip amount cannot be quickly recovered).

  In the second technique, when the engine output reduction rate is set to the above-described value, there is a problem that engine traction control becomes excessive in the case of three-wheel slip, and engine traction control in the case of four-wheel slip. There has been a problem of delays.

  Therefore, an object of the present invention is to provide a traction control device that can suppress excessive engine traction control and delay in engine traction control.

  The present invention that solves the above-described problems includes at least one wheel speed out of a plurality of wheel speeds detected by a wheel speed detecting means provided on all driving wheels, or an average value of the plurality of wheel speeds, and an estimated vehicle body A traction control device including an engine traction control unit that determines that the vehicle has slipped when the slip amount obtained from the estimated vehicle body speed calculated by the speed calculation unit exceeds a predetermined threshold, and reduces the engine torque. The number of slip wheels for calculating the number of slipped wheels by determining whether or not the slip amount of each drive wheel obtained from each wheel speed of each drive wheel and the estimated vehicle body speed is greater than a predetermined value. The engine traction control means increases the engine torque as the number of wheels calculated by the slip wheel number calculation means increases. Characterized in that it is configured to gel so.

  Here, the “slip amount” refers to a value indicating the degree of slip, such as the difference between the wheel speed and the estimated vehicle body speed and the slip rate. Further, the “predetermined value” for comparison with each wheel speed need not always be the same value, and may be changed as appropriate, for example, so as to decrease as the number of slipped wheels increases. Specifically, for example, in a two-wheel drive vehicle, a large predetermined value is used when judging the slip of the first wheel, and when judging that the first wheel slips and judging the slip of the second wheel, 1 A value smaller than the value used when the wheel slips may be used.

  According to the present invention, for example, in a two-wheel drive vehicle, when only the left drive wheel of the left and right drive wheels slips, the engine traction control means controls the wheel speed of the left drive wheel and the estimated vehicle body. The slip wheel number calculating means calculates the number of slipped wheels (here, one wheel) based on the respective wheel speeds of the left and right drive wheels and the estimated vehicle body speed. Then, after determining that the engine traction control unit has slipped as described above, the engine traction control unit refers to the number of wheels calculated by the slip wheel number calculating unit, and at a predetermined reduction rate corresponding to the number of wheels (one wheel). Reduce engine torque. Further, when all of the left and right drive wheels slip, the engine traction control means refers to the number of wheels (two wheels) calculated by the slip wheel number calculation means, and determines a predetermined reduction rate (2 The engine torque is greatly reduced at a reduction rate greater than the reduction rate of one wheel).

  Note that the estimated vehicle body speed calculating means in the present invention can be configured to calculate the estimated vehicle body speed based on at least a signal from the longitudinal acceleration detecting means for detecting the longitudinal acceleration of the vehicle. According to this, since the estimated vehicle speed calculation means calculates the estimated vehicle speed based on the longitudinal acceleration applied to the vehicle, the estimated vehicle speed is preferably used in a vehicle having no driven wheels such as a four-wheel drive vehicle. Can be calculated.

  Further, the estimated vehicle speed calculation means in the present invention is configured to calculate the estimated vehicle speed based on a wheel speed detected by a wheel speed detection means provided on at least one of the driven wheels. be able to. According to this, the estimated vehicle body speed calculating means calculates the estimated vehicle body speed based on the wheel speed of the driven wheel that does not cause the slip, so that the estimated vehicle body speed can be satisfactorily calculated as a value close to the actual vehicle body speed. it can.

  According to the present invention, the engine torque is greatly reduced as the number of slipped wheels increases. Therefore, the engine traction control becomes excessive as compared with the conventional structure in which the engine traction control is performed at a constant reduction rate. Delay in traction control can be suppressed.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a block diagram showing a vehicle equipped with a traction control device according to this embodiment, and FIG. 2 is a block diagram showing the configuration of the traction control device.

  As shown in FIG. 1, the vehicle CR is a two-wheel drive vehicle mainly including an engine ENG, a transmission TM, and a front differential Df. A wheel speed sensor (wheel speed detection means) 10 and a traction control are provided at appropriate positions. A device 20 is provided.

  The engine ENG is configured such that the output varies according to the amount of depression of an accelerator pedal (not shown), and the output varies depending on a control signal from the traction control device 20. The drive torque from the engine ENG is transmitted to the left and right front wheels (drive wheels) Tf via the transmission TM and the front differential Df. Note that any method may be used for changing the output. For example, a method for adjusting the opening of the throttle valve, a method for adjusting the supercharging pressure, or the like may be employed.

  The wheel speed sensor 10 is provided on the left and right front wheels Tf and the right rear wheel Tr which is a driven wheel (hereinafter, each wheel Tf, Tr is also simply referred to as “wheel T”), and the wheel speed of each wheel T is determined. Detected. Each wheel speed sensor 10 is connected to the traction control device 20, whereby the traction control device 20 can acquire the wheel speeds of the two front wheels Tf and the one rear wheel Tr. .

  The traction control device 20 has a function of calculating the number of slipped wheels based on a signal from each wheel speed sensor 10 and performing engine traction control based on the number of wheels. Here, the traction control device 20 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and performs various arithmetic processes based on signals from the wheel speed sensors 10 and programs and data stored in the ROM. By doing so, engine traction control is executed.

Hereinafter, the traction control device 20 will be described in detail with reference to FIG.
As shown in FIG. 2, the traction control device 20 mainly includes estimated vehicle speed calculation means 21, engine traction control means 22, and slip wheel number calculation means 23.

  The estimated vehicle speed calculation means 21 has a function of calculating the estimated vehicle speed Vb based on the wheel speed detected by the wheel speed sensor 10 on the driven wheel side. When the estimated vehicle speed calculation means 21 calculates the estimated vehicle speed Vb, the estimated vehicle speed Vb is output to the engine traction control means 22 and the slip wheel number calculation means 23.

  The engine traction control means 22 includes a slip determination unit 22a and an engine output decrease rate determination unit 22b. The slip determination unit 22a compares each signal from the two wheel speed sensors 10 on the drive wheel side with a signal from the estimated vehicle speed calculation means 21 to determine whether or not the drive wheel (front wheel Tf) has slipped. Has the function to judge. Specifically, the slip determination unit 22a is configured to calculate an average value of the two wheel speeds (the left wheel speed VL and the right wheel speed VR) detected by the wheel speed sensor 10 on the driving wheel side (the left and right average wheels in FIG. 3). A function of determining that the vehicle has slipped when the difference between the speed Va) and the estimated vehicle speed Vb calculated by the estimated vehicle speed calculation means 21 is greater than a predetermined threshold value α (see FIG. 3). is doing. And when this slip determination part 22a determines with having slipped, the signal which shows that is output to the engine output fall rate determination part 22b.

  When the engine output decrease rate determination unit 22b receives a signal from the slip determination unit 22a, the engine output reduction rate determination unit 22b refers to the number of wheels output from the slip wheel number calculation unit 23, and engine output (engine torque) based on the number of wheels. Has a function of determining the rate of decrease of Specifically, when the number of wheels from the slip wheel number calculation means 23 is “1”, the engine output reduction rate determination unit 22b stores the number of wheels in advance in, for example, a ROM (not shown). The reduction rate for one-wheel slip is derived by putting it into a map (map showing the relationship between the number of slip wheels and the engine output reduction rate). In addition, when the number of wheels from the slip wheel number calculating means 23 is “2”, the engine output reduction rate determination unit 22b inserts the number of wheels into the map to reduce for one wheel slip. A reduction rate for two-wheel slip greater than the rate is derived.

  The engine output reduction rate determination unit 22b also has a function of starting engine traction control at the reduction rate when the reduction rate is derived by the procedure as described above. The engine output reduction rate determination unit 22b determines the reduction rate by always referring to the number of wheels and the map from the slip wheel number calculation means 23 while the signal is output from the slip determination unit 22a. ing. Therefore, this engine output reduction rate determination unit 22b, for example, when the number of wheels from the slip wheel number calculation means 23 has changed to “2” after starting engine traction control with a reduction rate for one-wheel slip, The engine traction control is performed by switching from a reduction rate for one-wheel slip to a reduction rate for two-wheel slip. When the output of the signal from the slip determination unit 22a is stopped, the engine output reduction rate determination unit 22b ends the engine traction control.

  The slip wheel number calculating means 23 is the estimated vehicle body speed calculated by the estimated vehicle body speed calculating means 21 and each wheel speed (left wheel speed VL and right wheel speed VR) detected by the two wheel speed sensors 10 on the drive wheel side. It has a function of calculating the number of slipped wheels by determining whether or not the difference from the speed Vb is larger than a predetermined value β (see FIG. 3). Specifically, when the slip wheel number calculating means 23 determines that both of the two wheel speeds VL and VR are equal to or less than the predetermined value β, the number of wheels is set to “0”, and one of the wheels is determined. When it is determined that the speed (for example, VL) is greater than the predetermined value β, the number of wheels is set to “1”, and when both are determined to be greater than the predetermined value β, a function is provided to set the number of wheels to “2”. is doing. The slip wheel number calculating means 23 does nothing when it is determined that the number of wheels is “0”, and indicates that when it is determined that the number of wheels is “1” or “2”. The signal is output to the engine output reduction rate determination unit 22b.

  Next, engine traction control by the traction control device 20 will be described. In the drawings to be referred to, FIG. 3 is a time chart showing the relationship among the engine torque, each wheel speed, and the estimated vehicle body speed of the vehicle according to the present embodiment.

  As shown in FIG. 3, for example, when trying to start the vehicle CR in a stopped state on a split road surface where the road surface on the left side of the vehicle is an ice burn, When the vehicle CR starts mainly by pulling the vehicle CR with the front wheels Tf), the estimated vehicle body speed Vb is calculated based on the wheel speed of the rear wheel Tr that is the driven wheel of the vehicle CR. Then, when the slip amount of the left front wheel Tf among the drive wheels increases with time from the start of start (when VL moves away from Vb), the average of the wheel speeds of the left and right front wheels Tf after a predetermined time. The value (right and left average wheel speed Va) exceeds a value obtained by adding a predetermined threshold value α to the estimated vehicle body speed Vb (hereinafter referred to as “first threshold value [Vb + α]”), and engine traction control is started. (Time T1). In the engine traction control at this time, only the left wheel speed VL exceeds the value obtained by adding a predetermined value β to the estimated vehicle body speed Vb (hereinafter referred to as “second threshold value [Vb + β]”) at time T1. Therefore, since the number of wheels calculated by the slip wheel number calculating means 23 is “1”, the engine torque is reduced at a reduction rate for one-wheel slip (for example, a reduction rate smaller than the conventional one). It has become. As a result, the problem of excessive engine traction control during one-wheel slip as in the prior art is solved. Thereafter, when the left and right average wheel speed Va becomes equal to or lower than the first threshold value [Vb + α], the engine traction control is terminated (time T2).

  Further, when the left and right average wheel speed Va again exceeds the first threshold value [Vb + α] at time T3, engine traction control is started again. At this time as well, as described above, only the left wheel speed VL exceeds the second threshold value [Vb + β], and therefore, engine traction control is initially performed at a reduction rate for one wheel.

  At the time T4, when the right wheel speed VR exceeds the second threshold value [Vb + β], the number of wheels calculated by the slip wheel number calculating means 23 changes from “1” to “2”. The engine traction control is performed by switching from a reduction rate for one wheel to a higher reduction rate for two wheels. As a result, the time for the right front wheel Tf to slip is shortened, and the gripping force can be quickly recovered accordingly. Thereafter, when the right wheel speed VR becomes equal to or lower than the second threshold value [Vb + β], the reduction rate for the two wheels is switched to the reduction rate for the one wheel, and the engine traction control is continued (time T5). When Va becomes equal to or less than the first threshold value [Vb + α], the engine traction control ends (time T6).

According to the above, the following effects can be obtained in the present embodiment.
The more the number of wheels that slip, the more the engine torque is reduced. Therefore, the engine traction control becomes excessive and the engine traction control is delayed compared to the conventional structure that performs engine traction control at a constant rate of decrease. Can be suppressed.

As mentioned above, this invention is implemented in various forms, without being limited to the said embodiment.
In the above-described embodiment, the FF vehicle having the engine ENG and the driving wheels arranged on the front side of the vehicle is employed. However, the present invention is not limited to this, and an FR vehicle, MR vehicle, four-wheel drive vehicle, or the like may be employed. . However, in the case of a four-wheel drive vehicle, since there are no driven wheels as in the above-described embodiment, the estimated vehicle body speed calculation means includes, for example, a wheel speed sensor 10 provided on all the drive wheels as shown in FIG. Based on a signal from the sensor (longitudinal acceleration detecting means) 30, an estimated vehicle speed calculating means 24 for calculating an estimated vehicle speed may be employed. In such a four-wheel drive vehicle, a reduction rate that increases as the number of slipped wheels increases for one-wheel slip, two-wheel slip, three-wheel slip, and four-wheel slip, respectively. In addition, when engine traction control is performed only when three or more wheels slip (for example, when the number of wheels is two or less, control by a torque split controller), three-wheel slip, four-wheel It is only necessary to set the rate of decrease for slip.

In the above embodiment, the estimated vehicle body speed is calculated from the wheel speed of one driven wheel. However, the present invention is not limited to this. For example, the estimated vehicle body speed is calculated from the average value of the wheel speeds of two driven wheels. May be.
In the above embodiment, only engine traction control is performed. However, the present invention is not limited to this, and brake traction control may be performed simultaneously in addition to the engine traction control described above.
In the above embodiment, the difference between the wheel speed of the driving wheel and the estimated vehicle body speed is used as the slip amount. However, the present invention is not limited to this, and for example, the slip ratio, which is the ratio of the wheel speed to the estimated vehicle body speed, is used. It may be used.

It is a lineblock diagram showing the vehicles carrying the traction control device concerning this embodiment. It is a block diagram which shows the structure of a traction control apparatus. It is a time chart which shows the relationship between the engine torque of the vehicle which concerns on this embodiment, each wheel speed, and an estimated vehicle body speed. It is a block diagram which shows the structure of the traction control apparatus which concerns on other embodiment. It is a time chart which shows the relationship between the engine torque of a conventional vehicle, each wheel speed, and an estimated vehicle body speed.

Explanation of symbols

10 Wheel speed sensor (wheel speed detection means)
DESCRIPTION OF SYMBOLS 20 Traction control apparatus 21 Estimated vehicle speed calculation means 22 Engine traction control means 22a Slip determination part 22b Engine output reduction rate determination part 23 Slip wheel number calculation means CR Vehicle T Wheel Tf Front wheel (drive wheel)
Tr Rear wheel (driven wheel)
Vb Estimated vehicle speed Va Left and right average wheel speed VL Left wheel speed VR Right wheel speed

Claims (3)

At least one of the plurality of wheel speeds detected by the wheel speed detection means provided on all the driving wheels, or an average value of the plurality of wheel speeds, and an estimation calculated by the estimated vehicle body speed calculation means In the traction control device having engine traction control means for determining that the slip has occurred when the slip amount obtained from the vehicle body speed is greater than a predetermined threshold and reducing the engine torque,
Slip wheel number calculation means for calculating the number of slipped wheels by determining whether or not the slip amount of each drive wheel obtained from each wheel speed of each drive wheel and the estimated vehicle body speed is larger than a predetermined value. With
The engine traction control means is configured to greatly reduce the engine torque as the number of wheels calculated by the slip wheel number calculation means increases. The traction control device according to claim 1,
The estimated vehicle body speed calculating means calculates the estimated vehicle body speed based on at least a signal from a longitudinal acceleration detecting means for detecting a longitudinal acceleration of the vehicle. The traction control device according to claim 1,
The estimated vehicle body speed calculating means calculates the estimated vehicle body speed based on a wheel speed detected by a wheel speed detecting means provided in at least one of the driven wheels. .

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