JP5015834B2 - Wheel slip detection device - Google Patents

Description

  The present invention relates to a wheel idling detection device for detecting idling of a wheel on a high friction coefficient road or a low friction coefficient road.

Conventionally, as a technique for detecting a driving slip (idling) of a wheel such as a wheel spin of a vehicle, as disclosed in Patent Document 1, for example, in a two-wheel drive vehicle in which a drive wheel and a driven wheel exist. In general, a technique of detecting from a wheel acceleration ratio between a driving wheel and a driven wheel is employed. On the other hand, for all-wheel drive vehicles that do not have driven wheels, a technique is generally adopted in which it is determined that slip has occurred when the wheel acceleration exceeds a threshold value.
JP 10-217933 A

  However, in the conventional technology as described above, if excessive acceleration occurs instantaneously due to the gear backlash of the transmission or torsion of the drive system, for example, it is erroneously determined that slip has occurred even in all the development progress of the dry road surface. There is a possibility. If the determination threshold is increased to prevent this, the detection of slip on the road surface with a low road surface friction coefficient may be delayed this time, and it is extremely difficult to set an optimum value.

  Therefore, in the past, sports vehicles have a setting that emphasizes all-developed performance on dry road surfaces with a high friction coefficient, and general vehicles have priority on slip detection on low friction coefficient roads. Therefore, alternative settings must be made according to the type of vehicle, and it is difficult to reliably detect idling of the wheels in all road conditions with one setting.

  The present invention has been made in view of the above circumstances, and provides a wheel idling detection device capable of detecting wheel idling early without causing erroneous judgment while using the same criterion regardless of road surface conditions. It is an object.

  In order to achieve the above object, an idling detection device for a wheel according to the present invention calculates a driving force applied to a wheel based on an input from a driving source to the transmission and an operating state of the transmission. And a running resistance calculation unit for calculating a running resistance of the vehicle including at least air resistance acting on the vehicle body based on the speed of the wheel, and by subtracting the running resistance from the driving force applied to the wheel, A margin driving force calculation unit that calculates margin driving force, and an idling determination unit that determines that idling has occurred in the wheel when the margin driving force falls below a preset threshold value. To do.

  According to the present invention, it is possible to detect wheel slipping early without causing erroneous determination while using the same determination criterion regardless of road surface conditions, and erroneous determination occurs even when suddenly starting on a high friction coefficient road. In addition, it is possible to detect wheel slipping early on a low friction coefficient road.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 relate to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of a vehicle control system, FIG. 2 is a functional block diagram relating to wheel slip detection processing, and FIG. 3 is a flowchart of wheel slip detection processing. is there.

  In FIG. 1, reference numeral 10 denotes a transmission control unit (hereinafter referred to as a transmission ECU) that controls the transmission. In the present embodiment, control of the transmission having a torque converter with a lock-up clutch is executed. The wheel idling detection process according to the present invention is executed. The transmission ECU 10 includes an engine control unit (hereinafter referred to as an engine ECU) 20 that controls the engine, a traction control unit (hereinafter referred to as a traction ECU) 30 that performs vehicle driving force control and braking force control via the ABS device 35, and an instrument. Other in-vehicle control units such as an instrument panel control unit (hereinafter referred to as instrument panel ECU) 40 that controls the display device 45 and meters arranged on the panel, and a network based on a communication protocol such as CAN (Controller Area Network) 100 and is connected via 100 to send control information and control instructions in both directions.

  The transmission ECU 10 is connected to a wheel speed sensor 11 that detects the speed of the wheel and a transmission input rotation speed sensor 12 that detects the input rotation speed to the transmission. When signals from these sensors 11, 12 and an engine torque signal and an engine speed signal from the engine ECU 20 via the network 100 are input to the transmission ECU 10, and the idling of the wheel is detected, the transmission ECU 10 sends the engine ECU 20 to the engine ECU 20. Torque down instruction, brake control instruction to traction ECU 30, and instruction to instrument panel ECU 40 for notification to the driver are output.

  If it is not determined in the transmission ECU 10 that the lockup is to be engaged / released, an ON / OFF signal for the lockup clutch is input from the engine ECU 20 to the transmission ECU 10.

As shown in the following equation (1), the idling detection of the wheel by the transmission ECU 10 is defined as a marginal driving force F3 that is a difference between the generated driving force F1 generated at the wheel and the running resistance F2 with respect to the generated driving force F1. Then, it is determined whether or not the wheel is idling by comparing the margin driving force F3 with a predetermined determination threshold value.
F3 = F1-F2 (1)

Specifically, the generated driving force F1 is a driving force that is applied from the engine to the wheels through the transmission and the final reduction gear, and is a transmission that is input from the engine to the transmission as shown in the following equation (2). It is obtained by multiplying the input torque Tin by the total gear ratio i and the efficiency η.
F1 = Tin × i × η (2)

Further, as shown in the following equation (3), the running resistance F2 depends on the acceleration resistance Rα due to the vehicle weight W and the acceleration α, the front projection area A of the vehicle, the air resistance coefficient Cd, and the square of the wheel speed V. It is obtained as a sum of the rolling resistance Re of the wheel by the air resistance Rd, the rolling resistance coefficient μ and the vehicle weight W.
F2 = Rα + Rd + Re (3)
However, Rα = W × α
Rd = Cd × A × V ²
Re = μ × W

Therefore, the expression (1) can be expressed by the following expression (4). The margin driving force F3 is the vehicle weight W, acceleration α, front projection area A of the vehicle, air resistance coefficient Cd, wheel speed V, rolling. It can be calculated based on parameters such as the resistance coefficient μ, the output of the engine as the drive source, and the operating state of the transmission.
F3 = Tin × i × η− (W × α + Cd × A × V ² + μ × W) (4)

  In the equation (4), when the idling of the wheel (foil spin) occurs when the friction coefficient of the road surface is low, the wheel speed V increases rapidly, the calculation result of the air resistance Rd becomes a large value, and the marginal driving force It shows that the calculation result of F3 is a negative value. On the other hand, when all development progresses on a dry road surface with a high friction coefficient on the road surface, no wheel spin occurs, and therefore, the calculation result of the marginal driving force F3 does not become negative from the equation (4). Therefore, the idling of the wheel can be detected by examining the magnitude relationship of the margin driving force F3.

  Therefore, the transmission ECU 10 includes a generated driving force calculation unit 15, a running resistance calculation unit 16, a margin driving force calculation unit 17, and an idling determination unit 18, as shown in FIG. Have.

  The generated driving force calculation unit 15 calculates the torque amplification factor of the torque converter based on the presence / absence of lockup and the input / output rotation speed of the torque converter (engine rotation speed and transmission input rotation speed). The transmission input torque Tin is calculated based on the engine torque transmitted from the engine ECU, and the generated driving force F1 is calculated by the above-described equation (2) using the total transmission ratio i and the efficiency η. When the transmission is a manual transmission, the engine torque is the transmission input torque Tin.

  At this time, regarding the total gear ratio i, when the transmission is CVT, the pulley ratio is calculated in the transmission ECU 10, and when it is not CVT (stepped automatic transmission, manual transmission, etc.) is selected. The transmission gear stage is detected by the transmission ECU 20 to obtain the gear ratio. Then, the total speed ratio i is calculated from the speed ratio based on the pulley ratio or speed and the other speed reduction ratio determined by the vehicle specifications.

  Further, the transmission efficiency η is obtained in advance by experiment or simulation in consideration of the characteristics of the target transmission, and is stored as a control constant in the transmission ECU 10. When the efficiency changes depending on the pulley ratio or the shift speed, the efficiency η is held as a map in the transmission ECU 10 and is read with reference to the map for each pulley ratio or the shift speed.

  The running resistance calculation unit 16 calculates the running resistance F2 from the vehicle weight W, the air resistance coefficient Cd, the front projection area A of the vehicle, the rolling resistance coefficient μ, the wheel speed V, the acceleration α, and the like according to the above equation (3). To do.

  The vehicle weight W, the air resistance coefficient Cd, and the front projection area A are values obtained in advance according to vehicle specifications, and are stored in advance in the transmission ECU 10. However, as for the air resistance coefficient Cd and the front projection area A, the multiplication value Cd × A of both is stored in the transmission ECU 10. Further, the rolling resistance coefficient μ is obtained in advance by experiments or simulations, and is similarly stored in the transmission ECU 10. On the other hand, the wheel speed V is a value detected by the wheel speed sensor 11 and the acceleration α is calculated from the wheel speed V.

  The marginal driving force calculation unit 17 calculates the difference between the generated driving force F1 and the running resistance F2 as the marginal driving force F3 and sends it to the idling determination unit 18. The idling determination unit 18 compares the margin driving force F3 with a preset determination threshold Fs, and determines that the wheel is idling when the margin driving force F3 becomes equal to or less than the determination threshold Fs. The determination threshold Fs is a value obtained in advance by experiment or simulation in consideration of the engine, transmission, tire characteristics, etc., and is used to determine whether or not the wheel is idling in relation to the marginal driving force F3. Is the value of

  When this wheel idling is determined, the transmission ECU 10 outputs to the engine ECU 20 and the traction ECU 30 a control instruction for reducing the engine output to reduce the torque and a brake control instruction via the ABS device 35, respectively. Further, a notification instruction is issued to the instrument panel ECU 40, a warning lamp of the display device 45 is turned on, and the driver's attention is given and a warning is issued.

  More specifically, the wheel idling detection process described above is performed by the program process shown in the flowchart of FIG. Next, this program processing will be described.

  First, in step S1, it is checked whether or not an execution condition for this process is satisfied. The execution condition of this process is, for example, when any of the following conditions (j1) and (j2) is satisfied. After the execution condition is satisfied, any of the following conditions (j3) to (j5) When established, the execution of this process is cancelled.

[Conditions]
(J1) Other priority control is not being executed (for example, control in snow mode or hold mode for running on a snowy road).
(J2) Wheel deceleration ≧ setting value (value determined by experiment etc.) and generated driving force F1 ≦ setting value (value determined by experiment etc.)

[Release condition]
(J3) When an execution condition for other priority control (for example, snow mode or hold mode) is satisfied (J4) During wheel spin mode determination (wheel idling determination) and when the accelerator pedal is depressed → released, the set time ( (J5) Wheel deceleration <setting value, and wheel deceleration <setting value, within set time (within time determined by experiment)

  When the execution condition is not satisfied or canceled in step S1, the routine is exited as it is. When the execution condition is satisfied, the process proceeds to step S2, and the signals from the wheel speed sensor 11 and the transmission input rotation speed sensor 12, While inputting the engine speed and engine torque from the engine ECU 20, the vehicle weight W stored in the transmission ECU 10, the acceleration α, the air resistance coefficient Cd multiplied by the front projection area A, Cd × A, rolling resistance Parameters such as coefficient μ and transmission efficiency η are read, and the process proceeds to step S3.

  In step S3, the transmission input torque Tin is calculated based on the presence / absence of lockup, the torque amplification factor of the torque converter, and the engine torque, and the current gear position of the transmission is detected to determine the total gear ratio i. Then, the generated driving force F1 is calculated using the transmission input torque Tin, the total transmission ratio i, and the efficiency η.

  In the subsequent step S4, acceleration resistance Rα due to vehicle weight W and acceleration α, air resistance Rd due to vehicle front projection area A, air resistance coefficient Cd and square of wheel speed V, rolling resistance coefficient μ and vehicle weight W The rolling resistance Re of the wheel is calculated, and the acceleration resistance Rα, the air resistance Rd, and the rolling resistance Re are totaled to calculate the running resistance F2.

  Thereafter, the process proceeds to step S5, and when the marginal driving force F3 is calculated by subtracting the running resistance F2 from the generated driving force F1, it is checked in step S6 whether the marginal driving force F3 is equal to or less than the determination threshold Fs. As a result, if F3> Fs, it is determined that no idling has occurred in the wheel and the process is exited. If F3 ≦ Fs, it is determined in step S7 that the wheel is idling.

  In step S8, a torque down instruction is transmitted to the engine ECU 20, and a brake control instruction is transmitted to the traction ECU 30 to perform control for suppressing idling of the wheels. Further, in step S9, in order to notify the driver's warning, a notification instruction is transmitted to the instrument panel ECU 40, and the process is exited.

  As described above, in the present embodiment, by introducing the concept of the marginal driving force F3, a unified determination criterion can be used without causing erroneous determination or detection error of wheel slipping for any road surface condition. . As a result, erroneous determination does not occur even when suddenly starting on a high friction coefficient road, and wheel idling can be detected early on a low friction coefficient road, thereby improving controllability and reliability. .

Overall configuration diagram of vehicle control system Functional block diagram related to wheel slip detection processing Wheel slip detection process flowchart

Explanation of symbols

10 Transmission control unit (Transmission ECU)
DESCRIPTION OF SYMBOLS 15 Generated driving force calculation part 16 Traveling resistance calculation part 17 Marginal driving force calculation part 18 Idling judgment part F1 Generated driving force F2 Running resistance F3 Marginal driving force Fs judgment threshold Rd Air resistance Re Rolling resistance Rα Acceleration resistance Tin Transmission input torque

Claims (1)

A driving force calculation unit for calculating a driving force applied to the wheel based on an input from the driving source to the transmission and an operating state of the transmission;
Based on the speed of the wheel, a running resistance calculation unit that calculates a running resistance of the vehicle including at least air resistance acting on the vehicle body,
A margin driving force calculation unit that calculates a margin driving force of the vehicle by subtracting the running resistance from the driving force applied to the wheels;
An idling determination unit for a wheel, comprising: an idling determination unit that determines that idling has occurred in the wheel when the marginal driving force is equal to or less than a preset threshold value.

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