JP4004184B2 - Wheel speed abnormality detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wheel speed abnormality detection device that detects an abnormality of a wheel speed sensor or the like.
[0002]
[Prior art]
A conventional wheel speed abnormality detection device is described in Japanese Patent No. 2803472. This device recognizes that the speed difference between the left and right driven wheels exceeds a predetermined value as an abnormality in the wheel speed sensor.
[0003]
[Problems to be solved by the invention]
However, if the wheel speed sensor that gives the minimum wheel speed fails and is in an abnormal state, this must be detected.
[0004]
This invention is made | formed in view of such a subject, and it aims at providing the wheel speed abnormality detection apparatus by which the misjudgment was suppressed.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the present invention determines the following case as a wheel speed sensor failure in a wheel speed abnormality detection device that detects a wheel speed sensor failure of a vehicle having a plurality of drive wheels that are traction controlled .
(1) The wheel speed detected for the specific drive wheel is substantially zero.
(2) No braking force is applied to the specific drive wheel.
(3) A braking force is applied to the wheels other than the specific drive wheel, and the brake hydraulic pressure of the brake fluid of each wheel is equal to or higher than the reference pressure.
(4) The acceleration of the wheels other than the specific drive wheel is not more than the reference acceleration.
(5) The maximum wheel speed deviation between the wheels other than the specific drive wheel is not more than a predetermined deviation.
(6) The braking hydraulic pressure deviation of the brake fluid of the wheel pair having no specific drive wheel among the front wheel pair and the rear wheel pair is equal to or less than a reference value.
According to the present invention, since the wheel speed abnormality is detected only when the wheels other than the specific drive wheels are in a predetermined state, erroneous determination is suppressed as compared with the conventional case.
[0006]
The predetermined condition is, if the wheel speed deviation between the particular wheel other than the drive wheel braking force is not given includes state is less than the predetermined deviation preferred. That is, since there is almost no wheel speed deviation during steady straight running, the determination reliability can be improved by detecting an abnormality in such a case.
[0007]
It is preferable that all the wheels of the vehicle can be traction-controlled drive wheels.
[0008]
In this case, it is further preferable that the predetermined state includes a state in which braking force is applied to wheels other than the driving wheel based on a wheel speed of the driving wheel to which braking force is not applied during traction control. . That is, when one wheel speed information is abnormal, for example, the wheel speed during high-speed traveling is zero km / h, if other wheels are traction controlled based on this information, the viewpoint of slip suppression Naturally, braking force is applied to these wheels. Therefore, if such a case is included in the predetermined state, the reliability of the wheel speed abnormality detection can be further improved.
[0009]
Further, it is more preferable that the predetermined state includes a state in which acceleration (rotational acceleration) of wheels other than driving wheels to which no braking force is applied is equal to or less than a reference acceleration. That is, as described above, when one wheel speed information is abnormal, braking force is applied to the other wheels, so that the acceleration of the wheels is also below the reference acceleration. Therefore, if such a case is included in the predetermined state, the reliability of the wheel speed abnormality detection can be further improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the wheel speed abnormality detection device according to the embodiment will be described. The same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.
[0011]
FIG. 1 is a schematic configuration diagram of a vehicle equipped with a wheel speed abnormality detection device according to an embodiment.
[0012]
This vehicle includes four wheels (front wheels W _FL , W _FR , rear wheels W _RL , W _RR ) provided so as to be rotatable with respect to the vehicle body BDY. Wheel speed sensors 10, 10x, 10y, and 10z are respectively provided corresponding to the wheels W _FL , W _FR , W _RL , and W _RR , and their outputs are proportional to the wheel speed. Here, the wheel speed sensors 10, 10x, 10y, and 10z detect the rotational speed of the wheel electrically / magnetically or optically, and output an AC signal corresponding to the rotational speed.
[0013]
Outputs from the sensors 10, 10x, 10y, and 10z are input to a control device 100 such as an ECU (electronic control unit) or an ABS (anti-lock brake system) & TRC (traction control system) computer disposed in the vehicle. .
[0014]
The AC signal output from each sensor 10, 10 x, 10 y, 10 z is input to the processor 24 in the control device 100 via the A / D converter 12. The A / D converter 12 samples the AC signal from the wheel speed sensor at a predetermined sampling timing, converts it into a digital signal, and supplies the digital signal to the processor 24. The processor 24 processes digital signals using a program stored in the ROM 16, detects the wheel speed, and performs various controls. The processor 24, the ROM 16, and the RAM 18 can be constituted by a microcomputer.
[0015]
The control device 100 obtains the wheel speeds v _FL , v _FR , v _RL , and v _RR of each wheel based on the inputted wheel speed information and the like, and displays the vehicle speed calculated from the obtained wheel speed on the display. The brake control is executed based on the wheel speeds v _FL , v _FR , v _RL , and v _RR .
[0016]
As driving means for executing the brake control, the brakes B _FL , B _FR , B _RL , B _RR are provided on the wheels W _FL , W _FR , W _RL , W _RR . The brakes B _FL , B _FR , B _RL , B _RR are driven by a brake driving actuator ACT, and _apply braking force to the wheels W _FL , W _FR , W _RL , W _RR . As brake control, there are lock timing control of wheels W _FL , W _FR , W _RL , W _RR in ABS, slip suppression control by TRC, vehicle behavior control for posture stabilization, etc. Here, about slip control by TRC explain.
[0017]
A four-wheel drive (4WD) vehicle is a vehicle in which the four wheels W _FL , W _FR , W _RL , and W _RR can serve as drive wheels. That is, in the four-wheel drive travel mode, all the wheels W _FL , W _FR , W _RL , W _RR are drive wheels, and in the two-wheel drive travel mode, the front wheels W _FL , W _FR or the rear wheels W _RL , W _RR are driven. It becomes a circle.
[0018]
For example, while driving on a rough road in the four-wheel drive driving mode, the left front wheel _WFL slips by slipping on the road surface, and the other wheels W _FR , W _RL , W _RR contact the road surface so as not to slip. Suppose that In this case, at the time of traction control, to operate the brake B _FL by driving the actuator ACT brake drive, by stopping the idling giving braking force to the left front wheel W _FL, inhibit slippage.
[0019]
In order to perform this control, it is necessary to detect a slip state. When the wheel speed v _FL of the wheel is significantly higher than the reference wheel speed v _STD , this can be determined as a slip state.
[0020]
The reference wheel speed v _STD is the lowest of the detected wheel speeds (eg, v _RR , (can be replaced every hour)). That is, when the wheel speed deviation Δv (= v _FL −v _RR ) exceeds the predetermined deviation Δv ₀ , the control device 100 recognizes that the wheel W _FL is in the slip state, and drives the brake driving actuator ACT. operates the brake B _FL by, the idling is stopped by applying a braking force to the left front wheel W _FL.
[0021]
In other words, at the time of traction control, the control device 100 controls the actuator ACT so that the four wheels W _FL , W _FR , W _RL , W _RR do not slip based on the detected wheel speed or the like. Furthermore, in this apparatus, the control amount to the wheel W _FL is calculated based on the reference speed v _STD obtained from the lowest wheel speed v _RR and the wheel speed v _FL .
[0022]
By the way, the wheel speed sensor 10z which gives the lowest wheel speed v _RR fails, when there is an abnormal state, must be detected. Since the abnormality of the wheel speed sensor 10z caused by expansion of disconnection or sensor gap, while the wheel speed v _RR outputted always shall be substantially equal to zero, the wheel speed abnormality sometimes occurs in the control apparatus 100.
[0023]
When the wheel speed _vRR is abnormal, the following phenomenon is observed. In other words, when the following conditions are satisfied, it can be determined that the wheel speed is abnormal.
(1) First, the detected minimum reference wheel speed _vRR becomes zero or a value close thereto. That is, the wheel speed v _RR of the specific drive wheel is equal to or less than the predetermined wheel speed v ₁ . That is, v _RR ≦ v ₁ . The wheel speeds v _FL , v _FR , v _RL of the drive wheels W _FL , W _FR , W _RL are assumed to be large in this order.
(2) Since the detected speed is zero when the wheel W _RR is rotating normally, the braking force by traction control is not applied to the wheel W _RR (the brake is not applied). This state where the brake is not applied can be directly detected by detecting the control hydraulic pressure of the brake fluid indirectly by monitoring the instruction information from the control device 100 to the actuator ACT. In this case the control oil pressure P _RR brake fluid corresponding to the brake B _RR is equal to or less than the reference pressure P _R. That is, P _RR ≦ P _R.
(3) Since the wheel speed v _RR is substantially zero, the wheel speed deviation Δv based on the wheel speed v _RR easily exceeds the predetermined deviation Δv ₀ , so that the brakes B _FL , B _FR , B _RL are applied to the brake drive actuator ACT. And the braking force is applied to the wheels W _FL , W _FR , W _RL (the brake is applied). The state where the brake is applied can be directly detected by detecting the control hydraulic pressure of the brake fluid indirectly by monitoring the instruction information from the control device 100 to the actuator ACT. At this time, the control hydraulic pressures P _FL , P _FR , P _RL of the brake fluid corresponding to the brakes B _FL , B _FR , B _RL become the reference pressure P ₀ or more. That is, P _FL ≧ P ₀ , P _FR ≧ P ₀ , P _RL ≧ P ₀ .
(4) Since the brake is applied, the wheel accelerations G _FL , G _FR , G _{RL of the} wheels W _FL , W _FR , W _RL become the reference acceleration G ₀ or less. That is, G _FL ≦ G ₀ , G _FR ≦ G ₀ , G _RL ≦ G ₀ .
(5) If the vehicle is running in a steady straight line, the maximum deviation Δv ′ (= |) between the wheel speeds v _FL , v _FR , v _{RL of the} drive wheels W _FL , W _FR , W _RL to which the braking force is applied. v _FL −v _RL |) is a predetermined deviation v ₂ or less.
(6) Of the front and rear wheels, the one having no sensor that seems abnormal, that is, the control oil pressures P _FL and P _FR of the front wheels change in the same manner. Therefore, the deviation ΔP _F = (| P _FL −P _FR |) on the front wheel side is equal to or less than the reference value P ′. When the front wheel side sensor is out of order, the rear wheel deviation ΔP _R = (| P _RL −P _RR |) is equal to or less than the reference value P ′.
[0024]
Note that the threshold values P ₀ , G ₀ , and P ′ may be appropriately set to different values corresponding to the wheels and the like.
[0025]
In the present embodiment, when all of the above conditions (1) to (6) are satisfied for a predetermined time (T ₁ ) or longer, control device 100 determines that wheel speed sensor 10z is abnormal. If an abnormality is determined, the method for _obtaining the reference speed v _STD is changed. That is, when it is determined that the wheel speed sensor 10z is abnormal, the reference speed v _STD is obtained from, for example, the second smallest wheel speed instead of the lowest wheel speed v _RR . If the detected wheel speed V _RR exceeds v ₃ and continues for a predetermined time (T ₂ ) or more, it is determined that the cause of the abnormality has been removed, and the detected abnormal state information is reset.
[0026]
Moreover, since there are a plurality of conditions (1) to (6), the reliability can be improved .
[0027]
As described above, the wheel speed abnormality detection device detects a wheel speed abnormality detection device for a vehicle having a plurality of drive wheels W _FL , W _FR , W _RL , W _RR that are traction controlled. in the drive wheels _{W FL, W FR, W RL} , at least one W _RR (eg W _RR) brake force is not applied to the wheel speed (rotational speed) v _RR of the drive wheels W _RR is given A case where the value is equal to or less than v ₁ and the wheels W _FL , W _FR , W _RL other than the drive wheel W _RR are in a predetermined state is detected as a wheel speed abnormality. According to this device, since the wheel speed abnormality is detected only when the wheels W _FL , W _FR , W _RL other than the drive wheel W _{RR having} the predetermined speed v ₁ or less are in a predetermined state, an erroneous determination is made as compared with the conventional case. It is suppressed.
[0028]
This predetermined state preferably includes a state in which the wheel speed deviation Δv ′ between specific wheels other than the drive wheel W _RR to which no braking force is applied is equal to or less than the predetermined deviation v ₂ . Since there is almost no wheel speed deviation Δv ′ during steady straight running, the reliability of the determination can be improved by detecting an abnormality in such a case. This device is useful when all the wheels of a vehicle can be traction-controlled drive wheels.
[0029]
In addition, this predetermined state is controlled to the wheels W _FL , W _FR , W _RL other than the drive wheel W _RR based on the wheel speed v _RR of the drive wheel W _RR to which no braking force is applied during traction control. Includes power being applied. If one wheel speed information is abnormal, for example, the wheel speed during high-speed traveling is zero km / h, traction control is performed on the other wheels based on this information, from the viewpoint of slip suppression. Thus, braking force is applied to these wheels. Therefore, if such a case is included in the predetermined state, the reliability of the wheel speed abnormality detection can be further improved.
[0030]
Further, in this predetermined state, the accelerations (rotational accelerations) G _FL , G _FR , G _RL of the wheels W _FL , W _FR , W _RL other than the drive wheel W _RR to which no braking force is applied are less than the predetermined acceleration G ₀ . If the state is included, the reliability of wheel speed abnormality detection can be further improved.
[0031]
【The invention's effect】
According to the wheel speed abnormality detection device of the present invention, the erroneous determination can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a vehicle equipped with a wheel speed abnormality detection device according to an embodiment.
[Explanation of symbols]
W _FL , W _FR , W _RL , W _RR ... drive wheel, 100 ... control device, B _FL , B _FR , B _RL , B _RR ... brake.

Claims (3)

In a wheel speed abnormality detection device for detecting a wheel speed sensor failure of a vehicle having a plurality of drive wheels that are traction controlled,
The detected wheel speed of the specific drive wheel is substantially zero,
No braking force is given to the specific drive wheel ,
A braking force is applied to the wheels other than the specific drive wheel, and the braking hydraulic pressure of the brake fluid of each wheel is equal to or higher than a reference pressure.
The acceleration of wheels other than the specific drive wheel is below the reference acceleration,
The maximum wheel speed deviation between the wheels other than the specific drive wheel is a predetermined deviation or less,
When the brake hydraulic pressure deviation of the brake fluid of the wheel pair without the specific drive wheel among the front wheel pair and the rear wheel pair is below a reference value,
Wheel speed abnormality detecting apparatus for determining a wheel speed sensor failure. The wheel speed abnormality detection device according to claim 1 , wherein all the wheels of the vehicle can be traction-controlled drive wheels. The state of giving the determination condition includes a state in which braking force is applied to wheels other than the driving wheel based on the wheel speed of the driving wheel to which braking force is not applied during the traction control. The wheel speed abnormality detection device according to claim 2.

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