JPH08268252A - Speed display unit of vehicle equipped with braking force controller - Google Patents

Abstract

PURPOSE: To disuse any speed sensor so far equipped for speed displaying by effectively utilizing a wheel sensor, in a vehicle equipped with a braking force controller. CONSTITUTION: Each output of four wheel speed sensors 11 to 14 for controlling an automatic braking system is processed and a speed pulse is generated, while this speed pulse is converted into an alternating current signal, thereby outputting it to a speedmeter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed display device, and more particularly to a vehicle speed display device in a vehicle equipped with a braking force control device.

[0002]

2. Description of the Related Art Generally, an instrument panel of a vehicle is equipped with a speedometer for displaying a vehicle speed. Some speedometers of this type have a digital input signal. In this case, for example, an electromagnetic pickup type vehicle speed sensor is attached to the output side of the transmission that constitutes the power plant of the vehicle, and an AC electrical signal output from the electromagnetic pickup is integrated in the speedometer by an interface circuit. After being shaped into a rectangular pulse signal, the vehicle speed is calculated and displayed based on the pulse signal.

On the other hand, in this type of vehicle, a braking force control device for reducing the braking force acting on the wheel in the excessive slip state is provided for the purpose of preventing the wheel from locking or skiding during braking. May be For example, Japanese Patent Application Laid-Open No. 58-221752 is provided with a wheel speed sensor for detecting the rotational speed of a wheel, and based on the wheel speed indicated by a signal from these wheel speed sensors, a braking pressure for a wheel in an excessive slip state is provided. A configuration for increasing / decreasing pressure is shown.

[0004]

By the way, in the prior art, even in a vehicle equipped with a braking force control device, a vehicle speed sensor for displaying the vehicle speed is additionally provided, which is a solution for reducing the cost of the vehicle. It had to be an issue.

Therefore, the main object of the present invention is to eliminate the vehicle speed sensor provided for displaying the vehicle speed by effectively utilizing the wheel speed sensor provided in the braking force control device.

[0006]

That is, the invention according to claim 1 of the present application (hereinafter referred to as the first invention) increases or decreases the braking pressure based on the detection result of the wheel speed detecting means for detecting the rotation speed of the wheel. In a vehicle equipped with a braking force control device for pressing, a wheel speed signal processing means for processing the detection result of the wheel speed detecting means for a speedometer, and a vehicle speed signal for outputting the value processed by the processing means to the speedometer And output means.

The invention according to claim 2 of the present application (hereinafter referred to as the second invention) is provided with filter means for reflecting the output value in the previous value in the wheel speed signal processing means in the first invention. In addition, it is characterized in that a bad road detecting means for detecting a bad road traveling of the vehicle and a gain setting means for making the gain of the filter means smaller than usual when the bad road is traveling are provided.

The invention according to claim 3 of the present application (hereinafter,
In addition to the configuration of the first invention, a wheel speed signal determination means for determining whether or not a signal from the wheel speed detection means is input, and a vehicle body deceleration for detecting the vehicle body deceleration of the vehicle. Output means based on the vehicle deceleration detected by the vehicle deceleration detecting means when the signal from the wheel speed detecting means is not input during deceleration of the vehicle. It is characterized in that the estimated value of 1 is compared with the previous value, and the smaller value is output as the output value.

On the other hand, the invention of claim 4 of the present application (hereinafter,
A fourth invention) is, in addition to the configuration of the first invention, a wheel speed signal determining means for determining whether or not a signal from the wheel speed detecting means is input, and a vehicle body acceleration detecting means for detecting a vehicle body acceleration of the vehicle. And a wheel speed signal processing means for estimating an output value based on the vehicle body acceleration detected by the vehicle body acceleration detecting means when a signal from the wheel speed detecting means is not input during acceleration of the vehicle. It is characterized in that it is configured to compare with the previous value and output the smaller value as the output value.

The invention according to claim 5 of the present application (hereinafter,
In addition to the structure of the first invention, the fifth invention comprises a limiting means for limiting the change in the increasing direction of the output value of the wheel speed signal processing means to a predetermined value or less when the vehicle is braked. Characterize.

Further, an invention according to claim 6 of the present application (hereinafter referred to as a sixth invention) is provided with a failure diagnosing means for diagnosing a failure of the braking force control device, in addition to the configuration of the first invention. The vehicle speed signal output means is configured to continue the output state of the vehicle speed signal to the speedometer when at least one wheel speed detection means is normal even when the braking force control device has failed. To do.

[0012]

According to the above construction, the following operation can be obtained.

That is, in any of the first to sixth aspects of the invention, since the braking force control and the vehicle speed display are performed based on the detection result of the wheel speed detecting means, the vehicle speed sensor becomes unnecessary and the cost is reduced. Is planned.

In particular, according to the second aspect of the invention, since the gain of the filter means is reduced when the vehicle is running on a bad road, the degree of reflection of the previous value with respect to the output value of the wheel speed signal processing means becomes large, which causes When the vehicle travels on a rough road, the speed meter is prevented from moving.

According to the third aspect of the invention, when the signal from the wheel speed detecting means is not input during deceleration of the vehicle, the output calculated from the previous value of the output value of the wheel speed signal processing means and the vehicle deceleration. Since the smaller of the estimated values is selected as the output value, the output of the wheel speed detecting means falls below the detection limit and the wheel speed signal cannot be discriminated, for example, just before the vehicle stops. Even in this case, the vehicle speed display appropriately reflects the actual vehicle speed.

On the other hand, according to the fourth aspect of the invention, when the signal from the wheel speed detecting means is not input during acceleration of the vehicle, the output value calculated from the previous value of the wheel speed signal processing means and the vehicle body acceleration. Since the smaller one of the estimated value of is selected as the output value, the output of the wheel speed detecting means fluctuates near the detection limit when the vehicle starts, and the wheel speed signal is read, Even if it can not be read, the above output value will not change extremely,
As a result, the needle shake of the speedometer is prevented.

During braking, the wheels vibrate due to the frictional force between the wheels and the road surface, and the vibration resonates with the vehicle body, causing large noise in the output of the wheel speed detecting means.
It may cause a false display on the speedometer.

On the other hand, according to the fifth invention, when the vehicle is being braked, the change in the output value of the wheel speed signal processing means in the increasing direction is limited to a predetermined value or less. Therefore, the noise is effectively suppressed, and the erroneous display of the vehicle speed is prevented.

According to the sixth aspect of the invention, even when the failure of the braking force control device is determined, the output state of the vehicle speed signal to the speedometer is continued when the wheel speed detecting means for at least one wheel is normal. Therefore, the probability that three wheel speed detecting means will fail at the same time is extremely small, so that the vehicle speed is always displayed reliably.

[0020]

Embodiments of the present invention will be described below.

As shown in FIG. 1, the ABS controller 1 constituting the vehicle braking force control device includes a CPU and RA.
ABS control microcomputer 2 in which M, ROM, etc. are integrated in one chip, interface circuit 3 for converting AC wheel speed signals output from, for example, electromagnetic pickup type wheel speed sensors 11-14 into pulse signals, and ABS Drive circuits 4 ... 4 for driving the control solenoids 20 ... 20 and a well-known watchdog monitoring circuit 5 are provided. Here, the vehicle is a front engine / rear drive vehicle, and the wheel speed sensors 11 and 12 detect the wheel speeds of the left and right rear wheels, which are the driving wheels, and the wheel speed sensors 13 and 14, respectively.
Is configured to detect the wheel speeds of the left and right front wheels, which are driven wheels.

Then, the ABS control microcomputer 2 takes in the signals from the wheel speed sensors 11 to 14 through the interface circuit 3 and outputs the signal from the brake switch 15 for detecting the stepped state of the brake pedal (not shown). To generate an ABS control signal on the basis of these signals and output it to the ABS control solenoids 20 ... 20 via the drive circuits 4 ... 4 and to the watchdog monitoring circuit 5 with watchdog pulses at predetermined intervals. It is designed to output. In this case, the ABS control signal output from the ABS control microcomputer 2 is output to the drive circuits 6 ... 6 via the AND circuits 6 ...
The output of the watchdog monitoring circuit 5 is the AND circuit 6 ... 6
It is designed to be input to the input terminal of. in this case,
The watchdog monitoring circuit 5 is normally set to "1".
While continuing to output the (Hi) signal, it operates so as to switch the signal from "1" to "0" (Lw) at the time of abnormality such as interruption of the watchdog pulse. As a result, even if the ABS control microcomputer 2 runs out of control,
Since the output of the AND circuits 6 ... 6 is "0", AB
The ABS control signal is not output to the S control solenoids 20 ... 20 and the fail-safe property is ensured.

In this embodiment, a vehicle speed pulse is generated based on the wheel speed signal taken into the ABS control microcomputer 2 via the interface circuit 3, and this vehicle speed pulse is, for example, the ABS controller 1.
The vehicle speed signal conversion circuit 7 built in the converter converts the vehicle speed signal into an alternating current vehicle speed signal and then outputs it to the interface circuit 31 of the speedometer 30.

Next, referring to the flow chart of FIG.
The BS control main routine will be described.

The ABS control microcomputer 2 reads various signals in step S1 and then calculates the ABS wheel speed in step S2. That is, the ABS control microcomputer 2
For example, the rising edge of the wheel speed pulse fetched from the interface circuit 3 is counted, and as shown in FIG. 3, the time period T during the counting of a predetermined pulse number N (for example, 2) is measured. Then, the wheel speed W is calculated by substituting the pulse number N and the time period T into the following relational expression (1).

W = C1 · N / T (1) Here, C1 represents a predetermined conversion coefficient.

Next, the ABS control microcomputer 2 proceeds to step S3, calculates the vehicle speed pulse period To based on the wheel speed pulse, and executes a predetermined failure diagnosis process at step S4. Then, in step S5, it is determined whether or not the wheel speed sensors 11 to 14 are normal, and when it is determined that the wheel speed sensors 11 to 14 are normal, the process proceeds to step S6 to permit the output of the vehicle speed pulse. . As a result, in the ABS control microcomputer 2, a vehicle speed pulse having the vehicle speed pulse period To as one cycle is generated and output to the vehicle speed signal conversion circuit 7, as indicated by the symbol (a) in FIG. Then, in the vehicle speed signal conversion circuit 7, the vehicle speed pulse is converted into an AC vehicle speed signal as shown by the symbol (a) in the figure by CR discharge with the speed meter 30 and output to the speed meter 30. Become. In this case, since the vehicle speed signal (a) has a waveform similar to the signal obtained by the electromagnetic pickup type vehicle speed sensor, a conventionally used speed meter can be used as the speed meter 30. .

Returning to the flow chart of FIG. 2, when the ABS control microcomputer 2 determines in step S5 that the wheel speed sensors 11 to 14 are not normal, it proceeds to step S7 and executes a predetermined backup mode.

Next, the ABS control microcomputer 2 determines in step S8 whether or not the ABS control system is abnormal. When it is determined that the ABS control system is not abnormal, a predetermined ABS control process is executed in step S9. At the same time, when it is determined that the ABS control system is abnormal, the process proceeds to step S10, and the output of the watchdog pulse is prohibited, and the ABS control output is prohibited in step S11.

The vehicle speed pulse period calculation process is specifically performed as follows according to the flowchart of FIG.
That is, the ABS control microcomputer 2 executes the step S21.
Then, the vehicle speed pulse period To is calculated according to the following relational expression (2).

To = C2 · (<Tw1> + <Tw2>) / 2 (2) Here, <Tw1> indicates the average pulse cycle of the past six times of the left front wheel, which is the driving wheel, and <Tw2>, respectively. Similarly,> indicates the average pulse period of the right front wheel. And C2
Indicates a predetermined meter conversion division ratio. This is to correspond to the fact that the speed meter 30 is configured on the assumption that, for example, 8 pulses are input per rotation.

Next, the ABS control microcomputer 2 executes step S22 to execute a predetermined filtering process. That is, the ABS control microcomputer 2 performs a predetermined rough road determination, and when it is determined that the road is not a rough road, 1 is selected as the filter coefficient K as shown in Table 1 below. Further, when it is determined that the road is a bad road, the grades of the bad road are classified, and when it is determined that the bad road level is level 1 where the road surface condition is relatively gentle, the filter coefficient K is set to 0.
5 is selected as the filter coefficient K when it is determined that the rough road level is the level 3 where the road surface condition is extremely bad, and when it is determined that the rough road level is the intermediate level 2 between them, Selects 0.2 as the filter coefficient K. Then, by substituting the filter coefficient K selected in this way into the following relational expression (3), a value obtained by weighted averaging the vehicle speed pulse period To and its previous value To ′ is newly set as the vehicle speed pulse period To. .

To = (1−K) To ′ + KTo (3)

[0034]

[Table 1] Thus, when the vehicle is running on a rough road, the filter coefficient K
Becomes smaller and the gain becomes smaller, the degree of reflection of the previous value To ′ with respect to the vehicle speed pulse period To increases,
As a result, the needle shake of the speed meter during traveling on a rough road can be prevented.

Further, the ABS control microcomputer 2 determines in step S23 whether or not the vehicle is decelerating. When it is determined that the vehicle is decelerating, a predetermined deceleration correction process is executed in step S24, and then the process proceeds to step S25. Next, it is determined whether or not the vehicle is accelerating, and when it is determined that the vehicle is not decelerating, step S24 is skipped and the process proceeds to step S25 to determine whether or not the vehicle is accelerating. When it is determined that the vehicle is accelerating, after performing a predetermined acceleration correction process in step S26,
Return to the main routine.

In this embodiment, the deceleration correction process is performed as follows according to the flowchart of FIG. That is, the ABS control microcomputer 2 determines in step S31 whether the wheel speed pulse is in the non-pulse state. That is, it is determined whether the amplitude of the wheel speed signal input to the interface circuit has become too smaller than the threshold level and the output of the interface circuit has become a pulseless state. When it is determined that the wheel speed pulse is in the non-pulse state, step S32
Then, it is determined whether the vehicle speed pulse cycle estimated value Tpd calculated from the vehicle body deceleration is larger than the previous vehicle speed pulse cycle value To '. When it is determined that the vehicle speed pulse cycle estimated value Tpd is larger than the vehicle speed pulse cycle previous value To ′, in other words, the vehicle speed estimated value estimated from the vehicle body deceleration is higher than the vehicle speed indicated by the vehicle speed pulse cycle previous value To ′. When it is determined that it is smaller, step S33 is executed to replace the vehicle speed pulse cycle estimated value Tpd with the vehicle speed pulse cycle current value To. When it is determined that the vehicle speed pulse cycle estimated value Tpd is not greater than the vehicle speed pulse cycle previous value To ', step S34 is executed to execute the vehicle speed pulse cycle previous value T'.
Let o ′ be the vehicle speed pulse period current value To.

Therefore, when the vehicle is decelerated, the outputs of the wheel speed sensors 11 and 12 become smaller than the detection limit. For example, as shown by the symbol (c) in FIG. Even if the pulse is in the non-pulse state, the vehicle speed estimated value obtained from the vehicle body deceleration is displayed as the vehicle speed as shown by the broken line in the figure, and the vehicle speed display appropriately reflecting the actual vehicle speed is displayed. Will be done.

The acceleration correction process is specifically shown in FIG.
It is performed as follows according to the flowchart in FIG.

That is, the ABS control microcomputer 2 determines in step S41 whether the wheel speed pulse is in the non-pulse state. When it is determined that the wheel speed pulse is in the non-pulse state, the process proceeds to step S32 and it is determined whether the vehicle speed pulse cycle estimated value Tpa calculated from the vehicle body acceleration is larger than the previous vehicle speed pulse cycle value To '. When it is determined that the vehicle speed pulse cycle estimated value Tpa is larger than the vehicle speed pulse cycle previous value To ′, in other words, the vehicle speed estimated value estimated from the vehicle body deceleration is higher than the vehicle speed indicated by the vehicle speed pulse cycle previous value To ′. If it is determined to be small, step S
33 is executed to replace the vehicle speed pulse cycle estimated value Tpd with the vehicle speed pulse cycle current value To. When it is determined that the vehicle speed pulse cycle estimated value Tpa is not larger than the vehicle speed pulse cycle previous value To ', step S34 is executed to set the vehicle speed pulse cycle previous value To' to the vehicle speed pulse cycle current value T '.
o.

Therefore, for example, even when the output of the wheel speed sensors 11 and 12 fluctuates in the vicinity of the detection limit when the vehicle starts and the wheel speed signal is read or cannot be read, the vehicle speed pulse period To becomes extremely large. It does not fluctuate, which prevents needle shake of the speedometer 30.

Then, in this embodiment, the backup mode is performed as follows in accordance with the flowchart of FIG. That is, the ABS control microcomputer 2 determines in step S51 whether the drive wheels are failing. If it is determined that the drive wheels are failing, the process proceeds to step S52 and both drive wheels are failing. If it is determined that both drive wheels have not failed, the process proceeds to step S53 to continue outputting the vehicle speed pulse based on the wheel speed of the normal drive wheel.

When the ABS control microcomputer 2 determines in step S52 that both drive wheels are failing, the process proceeds to step S54 to prohibit the output of the vehicle speed pulse.

As described above, as a result of the failure diagnosis, the output of the vehicle speed pulse is continued when one of the wheel speed sensors for the drive wheels is normal, so that the vehicle speed is displayed even if the ABS system is stopped. Will be seen.

Next, a second embodiment of the deceleration correction process will be described with reference to the flowchart of FIG.

That is, the ABS control microcomputer 2 determines in step S35 whether or not the brake switch 15 is in the ON state. When it is determined that the brake switch 15 is in the ON state, the process proceeds to step S36, and the table in the following Table 2 is obtained. The guard value X is read in accordance with

[0046]

[Table 2] In that case, the table is set with the vehicle speed pulse period To as a parameter, and the value corresponding to approximately 1 G is the guard value X.

Then, the ABS control microcomputer 2 executes step S37 to determine whether or not the value obtained by subtracting the vehicle speed pulse cycle current value To from the vehicle speed pulse cycle previous value To 'is larger than the guard value X. If it is determined that the difference between the two is greater than the guard value X, then step S3
Proceed to step 8, and proceed from the vehicle speed pulse cycle previous value To 'to the guard value X
The value obtained by subtracting is the vehicle speed pulse period current value To. That is, the reduction amount of the vehicle speed pulse period is limited to the guard value X.

Therefore, when braking, the wheels vibrate due to the frictional force between the wheels and the road surface, and this vibration resonates with the vehicle body. As a result, as shown in FIG. 11, even if a large noise is generated, it is displayed as the vehicle speed. At this time, the noise portion is truncated and displayed as indicated by the broken line, whereby the noise is effectively suppressed and erroneous display of the vehicle speed is prevented.

Next, a second embodiment of the backup mode will be described.

That is, the ABS control microcomputer 2 determines in step S55 whether or not the drive wheels are failing. If it is determined that the drive wheels are failing, the process proceeds to step S56 and three or more wheels are failing. When it is determined whether or not three or more wheels have failed, the process proceeds to step S57, and a vehicle speed pulse is generated based on the average value of the upper two wheels of the normal wheels.

When the ABS control microcomputer 2 determines in step S56 that three or more wheels have failed, it proceeds to step S58 and prohibits the output of vehicle speed pulses.

[0052]

As described above, according to the present invention, in a vehicle having a braking force control device, the braking force control and the vehicle speed display are performed based on the detection result of the wheel speed detecting means. The vehicle speed sensor is not required, and the cost can be reduced.

In particular, according to the second aspect of the invention, since the gain of the filter means is reduced when the vehicle is running on a bad road, the degree of reflection of the previous value with respect to the output value of the wheel speed signal processing means becomes large, which causes When the vehicle travels on a rough road, the speed meter is prevented from moving.

Further, according to the third aspect of the invention, when the signal from the wheel speed detecting means is not input during deceleration of the vehicle, the output calculated from the previous value of the output value of the wheel speed signal processing means and the vehicle deceleration. Since the smaller of the estimated values is selected as the output value, the output of the wheel speed detecting means falls below the detection limit and the wheel speed signal cannot be discriminated, for example, just before the vehicle stops. Even in this case, the vehicle speed display appropriately reflects the actual vehicle speed.

On the other hand, according to the fourth aspect of the invention, when the signal from the wheel speed detecting means is not input during acceleration of the vehicle, the output value calculated from the previous value of the wheel speed signal processing means and the vehicle body acceleration. Since the smaller one of the estimated value of is selected as the output value, the output of the wheel speed detecting means fluctuates near the detection limit when the vehicle starts, and the wheel speed signal is read, Even if it can not be read, the above output value will not change extremely,
As a result, the needle shake of the speedometer is prevented.

According to the fifth aspect of the invention, when the vehicle is being braked, the change in the output value of the wheel speed signal processing means in the increasing direction is limited to a predetermined value or less. Occasionally, noise generated in the wheel speed detecting means due to the frictional force between the wheel and the road surface is effectively suppressed, and erroneous display of the vehicle speed is prevented.

According to the sixth aspect of the invention, even when the failure of the braking force control device is determined, the output state of the vehicle speed signal to the speedometer is continued when the wheel speed detecting means for at least one wheel is normal. Therefore, the probability that four wheel speed detecting means will fail at the same time is extremely small, so that the vehicle speed is always displayed reliably.

[Brief description of drawings]

FIG. 1 is a control system diagram of a vehicle including an ABS control system.

FIG. 2 is a flowchart showing a main routine of ABS control.

FIG. 3 is a schematic diagram showing an output of a wheel speed sensor and a waveform of a wheel speed pulse after waveform shaping.

FIG. 4 is a schematic diagram showing waveforms of vehicle speed pulses and vehicle speed signals output from the ABS control microcomputer.

FIG. 5 is a flowchart showing a vehicle speed pulse period calculation process.

FIG. 6 is a flowchart showing deceleration correction processing.

FIG. 7 is a time chart showing the operation of the vehicle in an extremely low speed range.

FIG. 8 is a flowchart showing an acceleration correction process.

FIG. 9 is a flowchart showing a backup mode.

FIG. 10 is a flowchart showing a second embodiment of deceleration correction processing.

FIG. 11 is a time chart diagram showing an operation of the embodiment.

FIG. 12 is a flowchart showing a second embodiment of the backup mode.

[Explanation of symbols]

 1 ABS Controller 2 ABS Control Microcomputer 11-14 Wheel Speed Sensor 30 Speed Meter

Claims (6)

[Claims] 1. A vehicle speed display device for a vehicle, comprising a braking force control device for increasing / decreasing a braking pressure based on a detection result of a wheel speed detecting device for detecting a rotation speed of a wheel, wherein the wheel speed detecting device detects the wheel speed. A braking force control device comprising: a wheel speed signal processing means for processing a result for a speedometer; and a vehicle speed signal output means for outputting a value processed by the processing means to the speedometer. Vehicle speed display device equipped with. 2. The wheel speed signal processing means is provided with a filter means for reflecting an output value from a previous value, and a bad road detecting means for detecting a bad road traveling of the vehicle,
2. A vehicle speed display device for a vehicle having a braking force control device according to claim 1, further comprising: a gain changing device for reducing the gain of the filter device to be smaller than usual when the vehicle travels on a rough road. 3. A wheel speed signal determining means for determining whether or not a signal is input from the wheel speed detecting means, and a vehicle body deceleration detecting means for detecting a vehicle body deceleration of the vehicle are provided. The signal processing means compares the estimated value of the output value based on the vehicle body deceleration detected by the vehicle body deceleration detecting means with the previous value when the signal from the wheel speed detecting means is not input during deceleration of the vehicle. The vehicle speed display device for a vehicle including the braking force control device according to claim 1, wherein the smaller value is output as an output value. 4. A wheel speed signal determining means for determining whether or not a signal is input from the wheel speed detecting means, and a vehicle body acceleration detecting means for detecting a vehicle body acceleration of the vehicle, and a wheel speed signal processing. The means compares the estimated value of the output value based on the vehicle body acceleration detected by the vehicle body acceleration detecting means with the previous value when the signal from the wheel speed detecting means is not input during acceleration of the vehicle, and the smaller value is compared. The vehicle speed display device for a vehicle including the braking force control device according to claim 1, wherein the vehicle speed display device is configured to output the value as an output value. 5. The control according to claim 1, further comprising: a limiter that limits a change in an increasing direction of an output value of the wheel speed signal processing unit to a predetermined value or less when the vehicle is being braked. A vehicle speed display device for vehicles equipped with a power control device. 6. A failure diagnosis means for diagnosing a failure of the braking force control device is provided, and the vehicle speed signal output means is
Even at the time of failure determination of the braking force control device, at least 1
The vehicle speed of a vehicle equipped with the braking force control device according to claim 1, wherein when the wheel speed detecting means for wheels and above is normal, the vehicle speed signal is continuously output to the speedometer. Display device.