JP2006123664A - Driving force control device for four-wheel-drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force control device for a four-wheel-drive vehicle capable of determining a driving state and optimally setting a driving force without using a conventional driving mode determination switch. <P>SOLUTION: The driving force control device detects (step S1) each wheel speed of the vehicle, calculates the difference between the wheel speed of a front wheel and the wheel speed of a rear wheel, determines the driving state of the vehicle based on the wheel speed difference between the front wheel and the rear wheel, calculates the vehicle body speed (step S2) according to the driving state, and detects (step S3) the idling of the driving wheel from the vehicle body speed and the wheel speed. When the idling of the driving wheel is detected, the starting of the control of the driving force in the driving wheel is determined from the wheel speed (step S4), and when the starting of the control of the driving force is determined, the control amount of the driving wheel is calculated according to the driving state, and the control amount calculated is set (step S5) on the driving wheel. The driving state can be determined without using the conventional driving mode determination switch, the control amount of the driving force is set according to the driving state, and the driving force of the idling driving wheel can be optimally set. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle driving force control device that controls the driving force of wheels according to the driving state of a four-wheel drive vehicle.

  As a technique for controlling the driving force of wheels according to the driving state of the vehicle and causing the vehicle to travel stably, there is a driving force control device for the vehicle. When the vehicle driving force control device is applied to a four-wheel drive vehicle capable of switching between two-wheel drive and four-wheel drive, the vehicle drive mode (two-wheel drive) is used to accurately recognize the wheel spin of the drive wheel. Driving or four-wheel driving). That is, in the conventional vehicle driving force control apparatus, as shown in FIG. 6, a drive mode determination switch 21 is provided in a drive mechanism (transfer or the like) 28, and a transfer mode (not shown) is driven by two-wheel drive. It is determined whether there is a four-wheel drive.

  As an example of the drive mode determination switch 21, one end 21 a is input to the drive control device 20 as shown in FIG. 7. Inside the drive control device 20, it is connected to the internal power supply 23 of the drive control device 20 via a resistor 22, and the other end 21b is connected to the ground. In the case of four-wheel drive, the drive mode determination switch 21 is turned on and the voltage is at the GND level, that is, 0 V. In the case of two-wheel drive, the drive mode determination switch 21 is turned off and the voltage of the internal power supply 23 is turned on. It was a level. The driving force control device 20 determines the two-wheel drive and the four-wheel drive by recognizing the voltage from the drive mode switch 21.

  By the way, the wheel spin is obtained by subtracting the vehicle body speed from the wheel speed. The wheel speed is generally obtained from wheel speed sensors 26FL, 26FR, 27RL, and 27RR provided on the wheels 24FL, 24FR, 25RL, and 25RR, respectively. In the case of two-wheel drive, the vehicle body speed is generally obtained from wheel speed sensors of driven wheels. In the case of four-wheel drive, the vehicle body speed is estimated from the wheel speed sensors 26FL, 26FR, 27RL, and 27RR of four wheels. The wheel speed sensors 26FL, 26FR, 27RL, 27RR and an acceleration sensor (not shown) are used for estimation. That is, if the same vehicle speed calculation method is applied to the two-wheel drive and the four-wheel drive, the vehicle speed in at least one of the drive modes is lowered, and the performance for controlling the driving force is deteriorated. Therefore, different calculation methods are used for two-wheel drive and four-wheel drive.

  Further, in a four-wheel drive vehicle (rear wheel drive-based four-wheel drive vehicle) that drives rear wheels during two-wheel drive, the four-wheel drive is improved in order to improve vehicle stability when traveling by two-wheel drive. The engine torque is greatly suppressed compared to the drive mode.

  Thus, conventionally, the calculation of the vehicle body speed and the torque command amount is separately used in the case of two-wheel drive and the case of four-wheel drive based on the determination result of the drive mode.

  Here, as a technique for accurately estimating the vehicle body speed according to the driving state as described above, in Patent Document 1 below, when it is determined that the vehicle is in the two-wheel driving state, a higher value is set among the wheel speeds of the non-driving wheels. When the vehicle speed is set and the two-wheel drive state is not determined, the lowest wheel speed of the four wheel speeds is set as the vehicle speed, so that the actual drive state and the drive state determination result differ This makes it possible to accurately estimate the vehicle speed even when it cannot be determined.

JP 2002-29402 A

  However, in the vehicle driving force control device 20 shown in FIG. 6, it is necessary to connect the vehicle driving force control device 20 and the drive mode determination switch 21, and therefore an input terminal (not shown) of the connector or the illustration. The input interface circuit (electric circuit) that does not need to be used is necessary, which increases the cost.

  In addition, if the connection between the drive mode determination switch 21 and the resistor 22 is disconnected, the drive mode determination switch 21 remains in an OFF state, and a state in which the drive mode switch 21 is ON cannot be detected. Since such a failure cannot be recognized by the driving force control device 20 of the vehicle, it is necessary to double the driving mode determination switch or change the switch to a switch that can detect disconnection, which increases costs. There was a problem.

  In the apparatus described in Patent Document 1, as described above, the vehicle body speed is accurately estimated as compared with the conventional case even when the actual driving state of the vehicle and the determination result of the driving state are different or cannot be determined. However, since the drive state detection switch that detects whether the transfer is in the two-wheel drive position or the four-wheel drive position is used, the input of the connector is similar to the above-described example of FIG. Terminals and input interface circuits are required, which increases the cost.

  Further, in a four-wheel drive vehicle that allows the differential of the center differential 28, that is, the difference between the average speed of the front wheels 24FL and 24FR and the average speed of the rear wheels 25RL and 25RR, even if the front and rear axles are in the four-wheel drive state. A rotation difference occurs. In this state, the calculation of the command amount for four driving is not optimal, and it may be better to largely suppress the engine torque by calculating the command amount for two driving.

  That is, in the four-wheel drive vehicle based on the rear wheel drive, in the case of the four-wheel drive that allows the differential of the center differential 28, the rear wheels 25RL and 25RR have wheel spins more excessively and the stability of the vehicle is reduced. In some cases, it is better to largely suppress the engine torque transmitted to the wheels 25RL and 25RR as in the two-wheel drive mode.

  Accordingly, the present invention has been proposed in view of the above-described problems, and can be used to determine a driving state without using a conventional driving mode determination switch, and a four-wheel drive vehicle capable of optimally setting a driving force. An object of the present invention is to provide a driving force control apparatus.

  A driving force control apparatus for a four-wheel drive vehicle according to the first invention that solves the above-described problem includes a wheel speed detection means for detecting each wheel speed of the vehicle, and a wheel speed of the front wheel detected by the wheel speed detection means. Front and rear wheel speed difference calculating means for calculating the difference between the wheel speed of the rear wheel and the vehicle body speed calculating means for calculating the vehicle body speed, and the driving wheel for detecting the idling of the driving wheel from each wheel speed and the vehicle body speed. When the idling of the driving wheel is detected by the idling detection means and the driving wheel idling detection means, the control amount calculating means for calculating the control amount of the driving wheel according to the front-rear wheel speed difference, and the control amount calculating means And control means for controlling the driving force of the driving wheel in accordance with the control amount calculated by.

  A driving force control device for a four-wheel drive vehicle according to a second invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the first invention, wherein the vehicle body speed calculation means includes: The vehicle body speed calculation method is changed according to the front and rear wheel speed difference.

A driving force control device for a four-wheel drive vehicle according to a third invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the second invention, wherein the vehicle body speed calculation means includes: A first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle can be calculated, and the first vehicle body speed is determined according to the front and rear wheel speed difference. Alternatively, the second vehicle body speed is set as the vehicle body speed.

  A driving force control device for a four-wheel drive vehicle according to a fourth invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the second invention, wherein the vehicle body speed calculation means includes: A first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle are calculated, and the first vehicle body speed and the second vehicle body speed are referred to. The vehicle body speed is obtained, and the reference ratio of the first vehicle body speed is increased as the front and rear wheel speed difference obtained by the front and rear wheel speed difference calculating means is larger.

  A driving force control device for a four-wheel drive vehicle according to a fifth invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the second invention, wherein the vehicle body speed calculation means includes: The front and rear wheel speeds calculated by the front and rear wheel speed difference calculating means can calculate a first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle. When the difference is greater than or equal to a first predetermined value, the first vehicle body speed is set as the vehicle body speed, and when the difference between the front and rear wheel speeds is less than a second predetermined value that is smaller than the first predetermined value, the second vehicle body speed is set. It is set as the vehicle body speed.

  A driving force control device for a four-wheel drive vehicle according to a sixth invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the first invention, wherein the control amount calculation means includes: A first control amount corresponding to the two-wheel drive state of the vehicle and a second control amount corresponding to the four-wheel drive state of the vehicle can be calculated, and the first control amount or the The second control amount is calculated as the control amount.

  A driving force control device for a four-wheel drive vehicle according to a seventh invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the first invention, wherein the control amount calculation means includes: A first control amount corresponding to the two-wheel drive state of the vehicle and a second control amount corresponding to the four-wheel drive state of the vehicle are calculated, and the first control amount and the second control amount are referred to. The control amount is obtained, and the reference ratio of the first control amount is increased as the front / rear wheel speed difference obtained by the front / rear wheel speed difference calculating means is larger.

  A driving force control device for a four-wheel drive vehicle according to an eighth invention that solves the above-described problem is the driving force control device for a four-wheel drive vehicle according to the first invention, wherein the control amount calculation means includes: The front and rear wheel speeds calculated by the front and rear wheel speed difference calculating means are capable of calculating a first control amount corresponding to the two-wheel drive state of the vehicle and a second control amount corresponding to the four-wheel drive state of the vehicle. When the difference is equal to or greater than a first predetermined value, the control amount is set as the first control amount. When the difference between the front and rear wheel speeds is equal to or smaller than a second predetermined value that is smaller than the first predetermined value, the control amount is set as the second control value. It is characterized by a quantity.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the first aspect of the present invention, in the driving force control according to the substantial driving state without using the driving state determination switch for determining the driving state as in the prior art. Since the control amount can be controlled, the cost can be reduced. Further, since it is not necessary to detect a failure of the drive mode determination switch, the reliability is improved.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the second invention, the same effect as the first invention is obtained, and the method for calculating the vehicle speed is changed according to the substantial driving state. Therefore, the control amount in the more optimal driving force control can be calculated, and the stability of the vehicle is improved.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the third invention, in addition to the same effects as the second invention, the first vehicle body speed or the second vehicle body speed depends on the substantial driving state. Therefore, the vehicle body speed can be easily set, and particularly suitable control for part-time four-wheel drive can be realized.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the fourth aspect of the present invention, the same effects as the second aspect of the invention can be achieved, and it is not necessary to predetermine the calculation of the vehicle speed and torque for driving force control. Thus, it is possible to perform calculations suitable for the generated differential, and in particular, it is possible to realize control suitable for four-wheel drive in which differential between the front and rear wheels is allowed.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the fifth aspect of the invention, in addition to the same effects as the second aspect of the invention, the control amount in the driving force control is appropriately set according to the front-rear wheel speed difference. The engine torque can be greatly suppressed, and the stability of the vehicle is improved.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the sixth aspect of the invention, the first control amount or the second control amount is obtained in accordance with the substantial driving state, in addition to the same effects as the first aspect of the invention. Since the control amount is set, the control amount can be easily set, and particularly suitable control for part-time four-wheel drive can be realized.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the seventh aspect of the invention, in addition to the same effects as the first aspect of the invention, it is not necessary to predetermine the calculation of the vehicle speed and torque for driving force control in a constant manner. The calculation suitable for the generated differential is possible, and in particular, the control suitable for the four-wheel drive in which the differential between the front and rear wheels is allowed can be realized.

  According to the driving force control apparatus for a four-wheel drive vehicle according to the eighth aspect of the invention, in addition to the same effects as the first aspect of the invention, the control amount in the driving force control is appropriately set according to the front-rear wheel speed difference. The engine torque can be greatly suppressed, and the stability of the vehicle is improved.

  The best mode for carrying out the driving force control apparatus for a four-wheel drive vehicle according to the present invention will be specifically described below based on the embodiments.

  FIG. 1 is a diagram showing an outline of a driving force control apparatus for a four-wheel drive vehicle according to a first embodiment of the present invention, and FIG. 2 is a diagram of the four-wheel drive vehicle according to the first embodiment of the present invention. FIG. 3 is a flowchart showing a control method of the driving force control device, and FIG. 3 is a flowchart for determining a driving state in the driving force control device of the four-wheel drive vehicle according to the first embodiment of the present invention.

  As shown in FIG. 1, the left and right front wheels 1FR and 1FL and the left and right rear wheels 2RL and 2RR of a vehicle on which the driving force control device 10 for a four-wheel drive vehicle according to the first embodiment of the present invention is mounted are Wheel speed sensors 3FL, 3FR, 4RL, 4RR, which are wheel speed detecting means for detecting the wheel speed, are respectively attached. Information regarding the speeds of the wheels 1FL, 1FR, 2RL, and 2RR detected by the wheel speed sensors 3FL, 3FR, 4RL, and 4RR is transmitted to the drive control device 10 of the vehicle. Each wheel 1FL, 1FR, 2RL, 2RR is provided with a braking device 5FL, 5FR, 6RL, 6RR that brakes each wheel 1FL, 1FR, 2RL, 2RR based on a command from the driving force control device. . The driving force of the engine is controlled based on a command from the driving force control device 10. The engine torque is transmitted to the wheels 1FL, 1FR, 2RL, 2RR via the transfer 8. The transfer 8 is a part-time four-wheel drive type that selectively switches between two-wheel drive and four-wheel drive.

  Next, a control method of the vehicle driving force control apparatus according to the first embodiment of the present invention will be described with reference to the flowcharts shown in FIGS.

(Step S1)
Based on the information from each wheel sensor 3FL, 3FR, 4FL, 4FR, the speed (wheel speed) of each wheel 1FL, 1FR, 2RL, 2RR is detected.

(Step S2)
Subsequently, the vehicle body speed is calculated according to the driving state.
Here, the process proceeds to step S11 shown in FIG. The difference between the wheel speeds of the left and right front wheels 1FL, 1FR and the wheel speeds of the left and right rear wheels 2RL, 2RR (front and rear wheel speed difference) is calculated (front and rear wheel speed difference calculating means). If the front-rear wheel speed difference is not less than the first predetermined value A, the process proceeds to step S12 (driving state determination means). If the front and rear wheel speed difference is smaller than the first predetermined value A, the process proceeds to step S13 (driving state determination means).

(Step S12)
It is determined that the vehicle is traveling by two-wheel drive, and the vehicle body speed is calculated by a vehicle speed calculation method for two-wheel drive (vehicle speed calculation means). That is, a wheel having a slow wheel speed is determined as a driven wheel, and the wheel speed of the driven wheel is set as a vehicle body speed (first vehicle body speed). Then, it progresses to step S3.

(Step S13)
It is determined that the vehicle is traveling by four-wheel drive, the vehicle speed is calculated by a vehicle speed calculation method for four-wheel drive, and the vehicle speed is estimated from each wheel speed (for example, the slowest wheel speed The estimated vehicle speed is calculated, and the vehicle speed (second vehicle speed) is calculated by adding information from the acceleration sensor to the estimated vehicle speed (vehicle speed calculation means). Then, it progresses to step S3.

(Step S3)
Wheel spin (idling of driving wheel) is detected, and the process proceeds to step S4.
That is, in the case of two-wheel drive, the wheel spin is detected from the vehicle body speed and the wheel speed, more specifically, the difference between the vehicle body speed and the left and right wheel speeds that are the drive wheels. The vehicle body speed and the wheel speed, specifically, the average wheel speed is calculated from the front left and right wheel speeds and the rear left and right wheel speeds, and the difference between the average wheel speed and each wheel speed exceeds a predetermined value. Is detected (driving wheel idling detection means).

(Step S4)
The start of driving force control in the driving wheel is determined according to the driving state. However, the start determination is made more sensitive than the determination of the drive mode by the conventional drive mode determination switch, thereby preventing the start delay.
In the case of two-wheel drive, if the front and rear average wheel speed difference between the front left and right average wheel speeds and the rear left and right average wheel speed is greater than or equal to a predetermined value, it is determined that the driving force needs to be controlled (control start The determining means) proceeds to step S5, and when the difference between the front and rear wheel speeds is smaller than the predetermined value, it is determined that it is not necessary to control the driving force (control start determining means), and the process ends.
In the case of four-wheel drive, the average wheel speed of the four wheels is calculated, and when the wheel speed difference between the average wheel speed and each wheel speed is a predetermined value or more, it is determined that the driving force needs to be controlled (control) The process proceeds to step S5. When the wheel speed difference is smaller than the predetermined value, it is determined that it is not necessary to control the driving force (control start determination unit), and the process ends.

(Step S5)
The control amount of the drive wheel is calculated according to the drive state, the control amount of the drive wheel is set, and the process ends.
In the case of two-wheel drive, the first control amount of the control device corresponding to the two-wheel drive state is calculated (control amount calculation means), and this first control amount is set to the idling drive wheel (control amount setting means). ).
In the case of four-wheel drive, the second control amount of the control device corresponding to the four-wheel drive state is calculated (control amount calculation means), and this second control amount is set to the idle driving wheel (control amount setting means). ).
At this time, the control devices 5FL, 5FR, 6RL, and 6RR may be controlled to control the torque acting on the wheels.
Alternatively, wheel spin detection (calculation) may be calculated independently for each wheel (four wheels for a four-wheel drive vehicle), and drive control start determination and control amount setting may be performed.

  Therefore, according to the driving force control apparatus for a vehicle according to the first embodiment of the present invention, the vehicle driving state (two-wheel driving or four-wheel driving) is detected only by the existing wheel speed sensors 3 and 4. Since the driving force can be optimally controlled based on this determination, it is not necessary to detect the failure of the switch such as the conventional driving mode determination switch itself and the input of the switch. Reduced. In addition, since the driving state can be determined without depending on the switch, the reliability is improved.

  Hereinafter, a control method of the vehicle driving force control apparatus according to the second embodiment of the present invention will be described with reference to FIGS. The outline of the drive control apparatus in this embodiment is the same as that shown in FIG. 1, but in the case of this embodiment, the transfer 8 has a built-in center differential, so that the differential between the front and rear wheels is different even in the four-wheel drive state. It is acceptable.

FIG. 4 is a flowchart for determining a driving state in the driving force control apparatus according to the second embodiment of the present invention, and FIG. 5 is a graph showing a summing ratio according to the driving state at that time.
The control method in the driving force control apparatus for a vehicle according to the second embodiment is a method for determining a driving state in the driving force control apparatus for a vehicle according to the first embodiment described above, and a calculation method for the control amount of the driving wheel accordingly. The other steps are the same as those in the method for controlling the vehicle drive device according to the first embodiment.

(Step S21)
The vehicle body speed is calculated using a calculation method according to the driving state.
The difference between the wheel speeds of the left and right front wheels 1FL, 1FR and the wheel speeds of the left and right rear wheels 2RL, 2RR (front and rear wheel speed difference) is calculated (front and rear wheel speed difference calculating means). When the difference between the front and rear wheel speeds is larger than the first predetermined value A, the process proceeds to step S22 (driving state determination means).
When the difference between the front and rear wheel speeds is equal to or less than the predetermined value A, the process proceeds to step S23 (driving state determination means).

(Step S22)
It is determined that the vehicle is substantially traveling by two-wheel drive, and the vehicle body speed is calculated by a vehicle speed calculation method for two-wheel drive (vehicle speed calculation means). That is, a wheel having a slow wheel speed is set as a vehicle body speed (first vehicle body speed). In step S5 in which the control amount of the driving wheel is calculated according to the driving state and the control amount of the driving wheel is set, the first control amount corresponding to the two-wheel driving state is calculated (control amount calculating means), This first control amount is set to the idling drive wheel (control amount setting means).

(Step S23)
When the front-rear wheel speed difference is larger than the second predetermined value B, the process proceeds to step S24.
When the difference between the front and rear wheel speeds is equal to or smaller than the second predetermined value B, the process proceeds to step S25.

(Step S24)
As shown in FIG. 5, according to the average wheel speed difference between the front and rear wheels, the first vehicle body speed by the vehicle speed calculation method for two-wheel drive and the second vehicle speed by the vehicle speed calculation method for four-wheel drive The vehicle speed is obtained by referring to both (vehicle speed calculation means). However, the reference ratio of the first vehicle body speed is increased as the average wheel speed difference between the front and rear wheels increases.
Further, in step S5 in which the control amount of the drive wheel is calculated according to the drive state and the control amount of the drive wheel is set, the second wheel drive state corresponding to the average wheel speed difference between the front and rear wheels is set. The control amount is obtained with reference to both the one control amount and the second control amount corresponding to the four-wheel drive state (control amount calculation means), and the control amount is set to the idle driving wheel (control amount). Setting means). However, the reference ratio of the first control amount is increased as the average wheel speed difference between the front and rear wheels increases.

(Step S25)
It is determined that the vehicle is running substantially by four-wheel drive, the vehicle speed is calculated by the vehicle speed calculation method for four-wheel drive, the vehicle speed is estimated from each wheel speed, and the estimated vehicle speed is calculated. The vehicle body speed (second vehicle body speed) is calculated by adding the information from the acceleration sensor to the estimated vehicle body speed (vehicle body speed calculating means). In step S5 in which the control amount of the driving wheel is calculated according to the driving state and the control amount of the driving wheel is set, the second control amount corresponding to the four-wheel driving state is calculated (control amount calculating means), The idle driving wheel is controlled based on the second control amount (control amount setting means).

  Therefore, according to the driving force control apparatus for a vehicle according to the second embodiment of the present invention, in addition to the operational effects exhibited by the driving force control apparatus for a vehicle according to the first embodiment of the present invention, the average of the front and rear wheels Optimum because the vehicle speed is calculated by referring to the first vehicle speed based on the vehicle speed calculation method for two-wheel drive and the second vehicle speed based on the vehicle speed calculation method for four-wheel drive according to the wheel speed difference. The vehicle body speed can be obtained, and a more optimal command amount can be transmitted to the idling drive wheels to suppress idling of the drive wheels. Further, when the average wheel speed difference between the front and rear wheels is not less than the second predetermined value B and not more than the first predetermined value A, the ratio of the first vehicle body speed to the vehicle body speed increases as the average wheel speed difference between the front and rear wheels increases. Therefore, it is possible to obtain a more optimal vehicle body speed and to transmit a more optimal command amount to the idling drive wheels to suppress idling of the drive wheels. Therefore, it is possible to perform a calculation suitable for the differential generated in the center differential without having to determine the vehicle speed and torque of the driving force control constant in advance. Further, even in the four-wheel drive state, the control amount in the driving force control can be set as in the two-wheel drive state, and the engine torque can be greatly suppressed, so that the stability of the vehicle is improved.

  In the above, when the average wheel speed difference between the front and rear wheels is larger in the range where the average wheel speed difference between the front and rear wheels is greater than or equal to the second predetermined value B and less than or equal to the first predetermined value A, the first vehicle body speed is referred to Although the ratio is increased so as to increase gradually, the ratio of the first vehicle body speed and the second vehicle body speed in the vehicle body speed may be increased stepwise.

  The present invention is used for a driving force control device of a four-wheel drive vehicle.

It is a figure which shows the outline | summary of the driving force control apparatus of the four-wheel drive vehicle which concerns on 1st Example of this invention. It is a flowchart which shows the control method of the driving force control apparatus of the four-wheel drive vehicle which concerns on 1st Example of this invention. It is a flowchart which determines the drive state of the driving force control apparatus of the four-wheel drive vehicle which concerns on 1st Example of this invention. It is a flowchart which determines the drive state of the driving force control apparatus of the four-wheel drive vehicle which concerns on 2nd Example of this invention. It is a graph which shows the total ratio by the drive state in the driving force control apparatus of the four-wheel drive vehicle which concerns on 2nd Example of this invention. It is a figure which shows the outline | summary of the drive control apparatus of the conventional four-wheel drive vehicle. It is the schematic of the drive mode determination switch used for the drive control apparatus of the conventional four-wheel drive vehicle.

Explanation of symbols

1 front wheel 2 rear wheel 3 front wheel speed sensor 4 rear wheel speed sensor 5 front control device 6 rear control device 7 engine 8 transfer 10 driving force control device

Claims (8)

Wheel speed detecting means for detecting each wheel speed of the vehicle;
Front and rear wheel speed difference calculating means for calculating the difference between the wheel speed of the front wheel detected by the wheel speed detecting means and the wheel speed of the rear wheel;
Vehicle body speed calculating means for calculating the vehicle body speed;
Drive wheel idling detection means for detecting idling of the drive wheel from each wheel speed and the vehicle body speed;
When the driving wheel idling detection means detects the idling of the driving wheel, the control amount calculating means for calculating the control amount of the driving wheel according to the front-rear wheel speed difference;
Control means for controlling the driving force of the drive wheel according to the control amount calculated by the control amount calculation means;
A driving force control apparatus for a four-wheel drive vehicle. 2. The driving force control apparatus for a four-wheel drive vehicle according to claim 1, wherein the vehicle body speed calculation means changes a calculation method of the vehicle body speed according to the difference between the front and rear wheel speeds. The vehicle body speed calculating means can calculate a first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle, and according to the front and rear wheel speed difference. The driving force control apparatus for a four-wheel drive vehicle according to claim 2, wherein the first vehicle body speed or the second vehicle body speed is set as the vehicle body speed. The vehicle body speed calculating means calculates a first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle, and the first vehicle body speed and the first vehicle body speed are calculated. The vehicle body speed is obtained with reference to two vehicle body speeds, and the reference ratio of the first vehicle body speed is increased as the front / rear wheel speed difference obtained by the front / rear wheel speed difference calculating means is larger. The driving force control apparatus for a four-wheel drive vehicle according to claim 2. The vehicle body speed calculation means can calculate a first vehicle body speed corresponding to the two-wheel drive state of the vehicle and a second vehicle body speed corresponding to the four-wheel drive state of the vehicle, and the front and rear wheel speed difference calculation means. The first vehicle body speed is set as the vehicle body speed when the difference between the front and rear wheel speeds obtained in step 1 is equal to or greater than a first predetermined value, and the front and rear wheel speed difference is less than a second predetermined value that is smaller than the first predetermined value. The driving force control device for a four-wheel drive vehicle according to claim 2, wherein the second vehicle body speed is sometimes set as the vehicle body speed. The control amount calculation means can calculate a first control amount corresponding to the two-wheel drive state of the vehicle and a second control amount corresponding to the four-wheel drive state of the vehicle, and according to the front and rear wheel speed difference. The driving force control apparatus for a four-wheel drive vehicle according to claim 1, wherein the first control amount or the second control amount is calculated as the control amount. The control amount calculating means calculates a first control amount corresponding to a two-wheel drive state of the vehicle and a second control amount corresponding to a four-wheel drive state of the vehicle, and the first control amount and the first control amount are calculated. The control amount is obtained with reference to two control amounts, and the reference ratio of the first control amount is increased as the front and rear wheel speed difference obtained by the front and rear wheel speed difference calculating means is larger. The driving force control apparatus for a four-wheel drive vehicle according to claim 1. The control amount calculation means can calculate a first control amount corresponding to the two-wheel drive state of the vehicle and a second control amount corresponding to the four-wheel drive state of the vehicle, and the front and rear wheel speed difference calculation means. The control amount is set as the first control amount when the difference between the front and rear wheel speeds obtained in step 1 is equal to or greater than a first predetermined value, and when the difference between the front and rear wheel speeds is less than a second predetermined value that is smaller than the first predetermined value, The driving force control apparatus for a four-wheel drive vehicle according to claim 1, wherein a control amount is the second control amount.

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