JPH0471739B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is based on the wheel speeds of a plurality of wheels.
The present invention relates to an estimated vehicle speed calculation device that calculates estimated vehicle speed.

[Conventional technology]

Conventionally, the brake hydraulic pressure of the wheels is controlled according to the slip rate of the wheels in order to solve problems such as deterioration of steering performance, inhibition of vehicle stability, and increase in braking distance caused by wheels locking during vehicle braking. Various anti-skid control devices have been proposed.

Here, to find the slip rate of the wheel,
It is necessary to determine wheel speed and vehicle body speed. For this reason, for example, in Japanese Patent Application Laid-open No. 54-96671, the larger of the maximum wheel speed signal of each wheel and a damping signal according to a preset vehicle speed attenuation rate during braking is output as an estimated vehicle speed signal. It has been shown that

[Problem to be solved by the invention]

However, when the estimated vehicle speed is calculated as described above, the wheel speed signal may be disturbed due to the vehicle driving on a rough road with severe unevenness, or the wheel speed may suddenly exceed the vehicle speed. When the vehicle returns to normal operation, the estimated vehicle speed may increase rapidly following an incorrect wheel speed signal. Due to this sudden increase in the estimated vehicle speed, the wheel slip rate calculated based on the estimated vehicle speed suddenly decreases. Therefore, there is a possibility that the brake pressure of each wheel is erroneously reduced and the braking distance becomes longer.

The present invention has been made in view of the above points, and an object of the present invention is to provide an estimated vehicle speed calculation device that can calculate estimated vehicle speed with high accuracy.

[Means to solve the problem]

In order to achieve the above object, an estimated vehicle speed calculation device according to the present invention, as illustrated in FIG. wheel speed detection means for detecting a wheel speed corresponding to the rotational speed of each wheel for the plurality of wheels; and a wheel speed among the wheel speeds of the plurality of wheels detected by the wheel speed detection means. a selection means for selecting a wheel speed as a candidate speed for the estimated vehicle speed from the above; an upper limit speed obtained by adding a speed calculated based on a predetermined acceleration to the previously calculated estimated vehicle speed; and a previously calculated estimated vehicle speed. A lower limit speed is set by subtracting a speed calculated based on a predetermined deceleration from the vehicle body speed, and three speeds are set: the set upper limit speed, the lower limit speed, and the wheel speed selected by the selection means. The gist of the present invention is an estimated vehicle speed calculating device characterized by comprising: calculation means for selecting an intermediate speed from among these and setting the selected speed as the current estimated vehicle speed.

[Effect]

According to the above configuration of the present invention, the estimated vehicle speed is
An upper limit speed obtained by adding a speed calculated based on a predetermined acceleration to the previously calculated estimated vehicle speed, and a lower limit obtained by subtracting a speed calculated based on a predetermined deceleration from the previously calculated estimated vehicle speed. The vehicle speed is determined to be an intermediate speed among the three speeds of the vehicle speed and the wheel speed selected by the selection means as a candidate speed for the estimated vehicle speed. Therefore, even if a wheel speed that is incorrectly detected when driving on a rough road or a wheel speed that has increased beyond the actual vehicle speed is selected as a candidate speed for the estimated vehicle speed, the estimated vehicle speed will not change. The acceleration and deceleration are suppressed to below a predetermined value. Therefore, the estimated vehicle speed is prevented from changing in accordance with the incorrect wheel speed, and it is possible to obtain an estimated vehicle speed that is closer to the actual vehicle speed.

〔Example〕

Next, a preferred embodiment in which the estimated vehicle speed calculation device according to the present invention is used in an anti-skid control device will be conceptually explained with reference to FIG.

In Figure 2, Vwt is the wheel speed of the driving wheels,
Vwr is the wheel speed of the right rolling wheel, Vwl is the wheel speed of the left rolling wheel, Vsb is the estimated vehicle speed, and Vs is the reference speed that is set as a value smaller than the estimated vehicle speed Vsb by ΔV and is the criterion for loosening the brake. FIG. 2 shows a case where the brake is operated after an acceleration slip occurs due to the driver's accelerator operation.

In this embodiment, before the start of braking, the estimated vehicle speed is determined from the intermediate wheel speed of the wheel speeds.
That is, until the start of braking is determined, the estimated vehicle speed Vsb is calculated from the intermediate wheel speed of the three wheel speeds (the wheel speed Vwr of the right rolling wheel in FIG. 2).
is required. When braking is started by turning on the stop switch due to the driver's brake operation, the estimated vehicle speed Vsb
is determined from the wheel speed Vwt of the driving wheel, which is the maximum wheel speed among the three wheel speeds. Here, in this embodiment, the estimated vehicle speed Vsb immediately after the start of braking is not immediately switched from the intermediate wheel speed to the maximum wheel speed, but is changed to the maximum wheel speed at a predetermined acceleration (angle) αup. To go. Therefore, according to this embodiment, if an acceleration slip occurs in one wheel, the estimated vehicle speed is calculated based on the remaining wheel speed excluding the wheel speed of the wheel where the acceleration slip occurred before braking. Vsb is required. Therefore, an appropriate estimated vehicle speed Vsb can be calculated without being affected by acceleration slip.
can be found.

Note that the above-mentioned start of braking is not determined to be the start of braking unless at least the driver performs a brake operation. Furthermore, when the wheel speeds of the left and right drive wheels are determined, and the estimated vehicle speed is determined from the four wheel speeds, it is desirable to determine the third wheel speed as the intermediate wheel speed.

Estimated vehicle speed Vsb obtained in this way
is a value that approximates the actual vehicle speed, and the reference speed Vs obtained from this estimated vehicle speed Vsb is:
The speed will not be excessively larger than the speed of each wheel of the rolling wheels. Therefore, good anti-skid control can be performed without reducing the hydraulic pressure of the brake device to a low level. The reason for calculating the estimated vehicle speed Vsb from the maximum wheel speed after the start of braking is that the maximum wheel speed is the closest to the actual vehicle speed when no acceleration slip occurs. .

Next, the above embodiment will be described in more detail with reference to the drawings.

FIG. 3 is a system diagram schematically showing the overall configuration of an anti-skid control device installed in a rear-wheel drive vehicle.

In the figure, 1 to 4 represent each wheel of the vehicle; 1 is the right front wheel, 2 is the left front wheel, 3 is the right rear wheel, and 4 is the left rear wheel. Numerals 5 to 7 are electromagnetic pickup type or photoelectric conversion type vehicle speed sensors for detecting the wheel speed, respectively. Of these, 5 is attached near the right front wheel 1, and
A right front wheel speed sensor 6 is installed near the left front wheel 2 and generates a signal according to the rotation of the left front wheel 2.
A left front wheel vehicle speed sensor 7 that generates a signal according to the rotation of the vehicle is attached to a propeller shaft 8 that transmits power to the right rear wheel 3 and the left rear wheel 4, which are drive wheels.
Rear wheel vehicle speed sensors 9 to 12 are hydraulic brake devices that generate signals in accordance with the rotation of the propeller shaft 8 corresponding to the average rotational speed of the right rear wheel 3 and the left rear wheel 4; is attached to the right front wheel 1, and the hydraulic brake device 10 is attached to the left front wheel 2.
The hydraulic brake device 11 is installed on the right rear wheel, and the hydraulic brake device 12 is installed on the left rear wheel 4.
13 is a brake pedal; 14 is a stop switch for detecting braking or non-braking depending on the state of the brake pedal 13; 15 is a hydraulic cylinder that generates brake hydraulic pressure when the brake pedal 13 is depressed; 16 is an engine rotation Represents a hydraulic pump that generates hydraulic pressure in response to. 17 to 19 are actuators that adjust the hydraulic pressure from the hydraulic cylinder 15 and the hydraulic pump 16 according to the output from an electronic control circuit 26 (described later) and send it to the hydraulic brake devices 9 to 12; A right front wheel actuator corresponding to the brake device 9, 18 a left front wheel actuator corresponding to the hydraulic brake device 10 of the left front wheel 2, and 19 a rear wheel 3, 4
This is a rear wheel actuator corresponding to the hydraulic brake devices 11 and 12. 20 to 23 are hydraulic pipes for guiding the adjusted hydraulic pressure from the actuators 17 to 19 to the hydraulic brake devices 9 to 12, of which 20 is for the right front wheel actuator 17.
and the hydraulic brake device 9 of the right front wheel 1, and 21 is the left front wheel actuator 18.
and the hydraulic brake device 10 of the left front wheel 2, and 22 is a rear wheel actuator 19.
and the hydraulic brake device 11 of the right rear wheel 3; 23 is a rear wheel actuator 19;
This represents a hydraulic conduit provided between the left rear wheel 4 and the hydraulic brake device 12 of the left rear wheel 4. 24 is electronic control circuit 2
Actuators 17 to 19 depending on the output of 6.
The main relay 25, which switches the connection between the electromagnetic solenoid and the power supply source, operates according to the output of the electronic control circuit 26 when a failure occurs in the anti-skid control device, such as when the electromagnetic solenoid is disconnected or when the stop switch 14 is disconnected. An indicator lamp used to notify the user that an abnormality has occurred in the system. 26 is an electronic control circuit which receives signals from the vehicle speed sensors 5 to 7 and the stop switch 14, performs arithmetic processing for anti-skid control, and outputs to control the actuators 17 to 19, the main relay 24 and the indicator lamp 25. represents something that occurs.

The right front wheel actuator 17, the left front wheel actuator 18, and the rear wheel actuator 19 are each connected to a hydraulic pump 16
Regulator part 2 that adjusts the hydraulic pressure from
7, a control valve section 28 including an electromagnetic solenoid for increasing/decreasing control for switching the direction of increase/decrease of brake oil pressure, and an electromagnetic solenoid for slow/sudden control for switching the gradient of increase/decrease of brake oil pressure into two stages, slow and fast. The hydraulic pressure adjustment unit 29 includes a brake hydraulic pressure adjustment unit 29, and the hydraulic pressure output from each actuator is applied to the brake and hydraulic pressure of each hydraulic brake device via each hydraulic pipe line.
The signal is transmitted to the wheel cylinders and brakes are applied to each wheel. In addition, the electromagnetic solenoid for increase/decrease control decreases the hydraulic pressure when energized, and
For example, the electromagnetic solenoid for sudden control is designed to have a steep increase/decrease gradient when energized.

The electronic control circuit 26 has a circuit configuration as shown in FIG. A pulse signal suitable for
The other waveform shaping amplifier circuits 31 and 32 are also configured to generate similar pulse signals. 33 is a buffer circuit electrically connected to the stop switch 14; 34 is a power supply circuit for supplying a constant voltage to the microcomputer 35 etc. when the ignition switch 41 is turned on; 35 is a CPU 35a;
ROM35b, RAM35c, I/O circuit 35d
It represents a microcomputer equipped with etc. 3
6 to 40 are each microcomputer 3
Of these, 36 is a right front wheel actuator drive circuit for driving the electromagnetic solenoid of the right front wheel actuator 17, and 37 is a drive circuit for driving the electromagnetic solenoid of the left front wheel actuator 18. 38 is a rear wheel actuator drive circuit for driving the electromagnetic solenoid of the rear wheel actuator 19; 39 is a normally open contact 24;
The main relay drive circuit 40 energizes the coil 24b of the main relay 24 having the reference numeral a to turn on the normally open contact 24a, and the reference numeral 40 represents an indicator lamp drive circuit for lighting the indicator lamp 25.

Next, the processing and operation of the anti-skid control device configured as described above will be explained.

When the ignition switch 41 is turned on,
A constant voltage from the power supply circuit 34 is applied to the microcomputer 35 etc.
The CPU 35a of No. 5 starts executing arithmetic processing according to a program preset in the ROM 35b.

FIG. 6 is a schematic flowchart showing the main part of this arithmetic processing. In this processing, first, only at the start of processing, initialization processing for subsequent processing is performed, for example, setting of various flags to be described later. Perform a reset, etc.

Thereafter, depending on the determination result at step 107, steps 102, 103, 104, 105, 106, and 107 are performed.
A series of processes or steps consisting of
A series of processes consisting of step 102, step 103, step 104, step 105, step 106, step 107, step 108, and step 109 are repeatedly executed until the ignition switch 41 is turned off.

In this series of processing, in step 102, control permission determination processing and control start determination processing are executed. That is, when calculating the estimated vehicle speed in estimated vehicle speed calculation processing step 104, which will be described later, the permission flag is used to instruct a change in the selection of the wheel speed that is one of a plurality of estimated vehicle speed candidates.
In addition to setting and resetting the facts,
Instructions to change the processing content of the traveling path determination processing step 103 (described later), instructions regarding whether or not to execute actuate pattern selection step 206, etc. in the timer interrupt routine (described later), and instructions to be calculated in the reference speed calculation processing step 105 (described later). The start flag Fsta is set/reset to instruct reference speed selection.

Next, in step 103, the type of road the vehicle is currently traveling on, the friction coefficient based on the road surface condition, and the unevenness of the road surface are estimated. It is either a medium μ road such as asphalt, or a low μ road such as an icy road, a so-called good road with a very gentle degree of unevenness, a so-called bad road with a certain degree of roughness, or a very rough road. A driving route determination process is executed to determine the nature of the road itself, such as a so-called extremely bad road (including a wavy road), which is likely to cause problems for anti-skid control, according to specific conditions. To briefly describe the content of this discrimination process, the corresponding wheel speed VW data calculated based on the signals from the individual vehicle speed sensors 5, 6, and 7 (however, for the rear wheel speed, the right rear wheel 3 (corresponds to the average wheel speed of the actual wheel speed of the left rear wheel 4 and the actual wheel speed of the left rear wheel 4), wheel acceleration V/W data, reference acceleration data of multiple levels stored in advance in the ROM 35b, Based on the plurality of reference speed data calculated in the reference speed calculation processing step 105, the wheel speed,
Processing corresponding to the magnitude comparison of various combinations of wheel acceleration, reference speed, and reference acceleration is performed, and a magnitude comparison is made between the value of the counter that is incremented or decremented according to the processing result and a predetermined set value. The travel route is finally determined based on the comparison result.

Next, in step 104, estimated vehicle speed calculation processing is executed. To give an overview of this process, when creating estimated vehicle speed data, there are three candidate speeds: the calculated wheel speed and the driving acceleration that can be obtained from the actual vehicle driving state (including during braking). The intermediate value of the upper and lower limit values, and the first and second estimated vehicle speeds calculated using two calculation formulas based on the estimated vehicle speed calculated in the previous estimated vehicle speed calculation process, etc. is determined as the estimated vehicle speed. In this case, the wheel speed, which is one of the candidate speeds, is set to the intermediate value of the three wheel speeds during the period in which the permission flag Fact is in the reset state as described above in the control permission/start determination processing step 102. On the other hand, during the period when the permission flag Fact is set, the wheel speed that takes the maximum value is selected as a candidate.

Next, in step 105, a reference speed calculation process is executed. For an overview of this process, refer to the start flag above.
Until Fsta is reversed from the reset state to set, that is, until the start of depressurization (which can also be called the start of control), the control start judgment reference speed is calculated, and after the start flag Fsta is set, that is, after the start of control, the road surface Actuator 1 due to road noise, etc. to prevent malfunction of the actuators 17 to 19 due to noise, electrical noise, etc.
Road noise (vehicle body vibration) countermeasure standard speed to prevent malfunctions of 7 to 19, decompression judgment standard speed which is one standard for starting decompression, intermediate μ which is a standard to determine intermediate μ road. Data corresponding to the determination reference speed and the low μ determination reference speed, which is a reference for determining a low μ road, are created using predetermined calculation formulas that include at least the estimated vehicle speed. Note that the control start determination reference speed is set in step 103 of the traveling route determination process in order to prevent at least one of the actuators 17 to 19 from starting an undesired pressure reduction due to slow braking, especially on a rough road. The value of the subtracted number in the arithmetic expression is made variable according to the characteristics of the road itself determined in . In addition, for the road noise (vehicle body vibration) countermeasure standard speed and decompression judgment standard speed, the value of the subtracted number in the corresponding calculation formula is variable, and the decompression speed standard can be switched depending on the rough road condition. This prevents excessive pressure reduction due to overcontrol.

Next, in step 106, a system abnormality check is executed. In this process, the data corresponding to the operating state of the system element during normal system operation stored in advance in the ROM 35b is compared with the data representing the operating state of the system element taken in at the time of the processing, and the system is detected as abnormal. When it is determined that there is no abnormality, an abnormality flag indicating the system operating state is set, and on the other hand, when it is determined that there is no abnormality, the abnormality flag is maintained at a reset state or reversed.

Next, in step 107, the abnormality flag is checked to determine whether or not there is a system abnormality. If it is determined that the abnormality flag is not set, that is, if the system is operating normally, the process proceeds to step 102 of the control permission and start determination process as described above. On the other hand, if it is determined that the abnormality flag is set, that is, if an abnormality has occurred in the system or if it is operating abnormally, steps 108 and 109 are sequentially executed, and the above-mentioned control permission and start judgment are performed. Proceed to processing step 102.

Step 108 is a step to notify the driver that an abnormality has occurred in the system so that he can confirm that the anti-skid control is not effective. Only when it is first determined that an abnormality has occurred, a control signal for lighting the indicator lamp is output to the indicator lamp drive circuit 40. Indicator lamp drive circuit 40, which receives this control signal, latches this control signal so that indicator lamp 25 continues to be lit. In this step 108,
After outputting the control signal as described above, if the system automatically returns to the normal operating state, a process is also executed to output a control signal to the indicator lamp drive circuit 40 to turn off the indicator lamp 25. Good too.

Step 109 is a step for performing fail-safe processing in the event of abnormal system operation.
Regardless of the driving state of the electromagnetic solenoids for increase/decrease control and the electromagnetic solenoids for slow/sudden control in each of 18 and 19, the non-antiskid control mode, that is, the brake oil pressure according to the depression of the brake pedal 13, is applied. In order to switch to the normal mode in which braking is performed, a process is performed to output a control signal to cut off the current supply to the coil 24b of the main relay 24. When the coil 24b is no longer energized, the previously closed normally open contact 24a is switched to its normal open state, thereby cutting off the power supply to the electromagnetic solenoids in each of the actuators 17, 18, 19.
Normal braking is performed at least until the system abnormality is resolved. In this system fail-safe processing step 109, in order to further improve safety, the power supply is cut off as described above, and each actuator drive circuit 3
A process of outputting a control signal for turning off the electromagnetic solenoids 6, 37, and 38 may also be executed.

FIG. 7 is a flowchart schematically showing a timer interrupt routine that is started to be executed at a predetermined cycle during the execution of the main arithmetic processing as described above in FIG.

In this timer interrupt routine, first, in step 201, a process of calculating the wheel speed of each wheel is executed. In this wheel speed calculation step 201, a predetermined value including a difference between a count value of vehicle speed pulses during the current process execution and a count value of vehicle speed pulses during the previous process execution, a time interval, and a constant is calculated. In addition to calculating the arithmetic expression, a filter process, that is, a process of averaging the wheel speeds obtained by calculating the arithmetic expression a plurality of consecutive times, is also performed as necessary. Note that the counting of the vehicle speed pulses is executed in a vehicle speed interrupt routine to be described later.

Next, in step 202, processing for calculating wheel acceleration for each wheel is executed. This wheel acceleration calculation step 202 includes the speed difference between the wheel speed calculated by executing the wheel speed calculation step 201 and the wheel speed calculated by the previous wheel speed calculation step 201, time, and a constant. In addition to calculating a predetermined arithmetic expression, processing substantially similar to the above-mentioned filter processing is also performed as necessary to neutralize the driving components of the wheel speed and wheel acceleration.

Next, in step 203, it is determined whether or not the permission flag Fact described above in FIG. 6 is set.
If the permission flag Fact is not set, that is, the stop switch 14 is not turned on, the process proceeds to step 204, whereas if the permission flag Fact is set, the process proceeds to step 204.
A route consisting of steps 205 to 208 is executed sequentially.

In step 204 above, the permission flag Fact
During the first process after the reset, a process is performed in which a control signal for this purpose is output to each of the actuator drive circuits 36, 37, and 38 in order to return all the actuators 17, 18, and 19 to the non-operating state. Each of the actuator drive circuits 36, 37, and 38 to which this control signal is input maintains a state corresponding to this control signal, stops energizing the electromagnetic solenoid of the corresponding actuator, and brake hydraulic pressure control is performed in the normal mode. Make it. Note that the above output processing does not need to be performed in the second and subsequent processing after the permission flag Fact is reset. This output step
After passing through 204, the process shown in FIG. 6, which has been interrupted, is normally continued.

On the other hand, in step 205 executed when the permission flag Fact is set, each wheel speed and each wheel acceleration calculated in the wheel speed calculation step 201 and the wheel acceleration calculation step 202,
Processing is executed to compare the various reference speeds calculated in step 105 of the reference speed calculation process shown in FIG. 6 with various preset reference accelerations.

Next, in step 206, a process is executed to select a drive pattern for each of the increase/decrease control electromagnetic solenoid and the slow/rapid control electromagnetic solenoid based on the results obtained in the comparison step 205. Note that various drive patterns corresponding to each solenoid are stored in advance in the ROM 35b.

Next, in step 207, the continuous time of the pressure increase mode and pressure reduction mode is monitored, and if the pressure reduction mode continues for longer than the time expected from normal anti-skid control, a permission flag is set.
In order to determine that there is a system abnormality even if Fact is being set, and force all actuators 17, 18, and 19 to be inactive in the next step 208, the actuator pattern selection step 206 is selected. A process for changing the drive pattern is executed.

Next, in step 208, a process is executed to output a control signal corresponding to the final drive pattern to the corresponding actuator drive circuits 36, 37, and 38. The actuator drive circuits 36, 37, and 38 to which this control signal has been input drive the corresponding actuators 17, 38, respectively, in response to this control signal.
A drive output that determines the drive state of 18 and 19 is performed. After passing through this output step 208, the process shown in FIG. 6, which has been interrupted, will normally continue to be executed.

Figure 8 shows one for each of vehicle speed sensors 5, 6, and 7.
This is a vehicle speed interrupt routine that is executed in correspondence with the vehicle speed sensor and waveform shaping amplification circuit, and this vehicle speed interrupt routine is executed as shown in FIG. The process is interrupted and execution is started. In this case, it goes without saying that priority is given in advance to the three vehicle speed interrupt routines in consideration of the case where interrupt instructions are generated simultaneously by two or more vehicle speed pulses.

In this vehicle speed interrupt routine, the steps
301 is executed and vehicle speed pulses are counted. Note that this count value is calculated at wheel speed calculation step 201 in the timer interrupt routine as described above.
Used when executing.

Next, the operation of each part controlled by the above-described processing will be briefly explained using FIG. 9, taking the right front wheel 1 as an example.

Fig. 9 assumes that when braking is started, the wheel speed VWr of the right front wheel 1 first decreases, then the wheel speed Vwl of the left front wheel 2, and the wheel speed Vwt of the rear wheels 3 and 4. Each wheel speed Vwt, Vwr, Vwl,
Right front wheel acceleration V〓wr, right front wheel actuator 1
7 shows the relationship between the operating states of the electromagnetic solenoid for increasing/decreasing control of the right front wheel actuator 17 and the electromagnetic solenoid for slow/sudden control of the right front wheel actuator 17, and the brake oil pressure output from the right front wheel actuator 17. .

In the figure, Vo is the actual vehicle speed, Vss, Vsn,
Vsh is the estimated vehicle speed at step 105 in Figure 7.
Various standard speeds calculated based on Vsb,
Vss is the control start judgment reference speed, Vsn is the road noise countermeasure reference speed, Vsh is the decompression judgment reference speed,
In this case, the control start determination reference speed Vss and the depressurization determination reference speed Vsh are determined from the estimated vehicle speed Vsb using the same speed difference ΔV. Also G1, G2, G
3 is reference acceleration data stored in advance in the ROM 35 as described above.

First, when the driver performs a brake operation at time to and the vehicle starts braking, the right front wheel speed
This anti-skid control is started at time t1 when Vwr becomes smaller than the control start judgment reference speed Vss, the electromagnetic solenoid for increase/decrease control and the electromagnetic solenoid for slow/sudden control are turned on (at the same time), and the brake oil pressure is The pressure is suddenly reduced.

When the brake hydraulic pressure is suddenly reduced from time t1 and the brake is released, the decrease in wheel speed Vwr slows down and wheel acceleration V〓wr starts to increase, and when it becomes larger than the reference acceleration G1 at time t2, the slow/sudden control electromagnetic Only the solenoid is turned off, and the brake oil pressure is slowly reduced. Then, when the wheel acceleration V〓wr increases further and becomes larger than the reference acceleration G2 at time t3, the electromagnetic solenoid for increase/decrease control is activated.
It is turned OFF and the brake oil pressure is gradually increased. Even when the brake oil pressure is gradually increased, the wheel acceleration still increases.
V〓wr continues to rise and becomes larger than the reference acceleration G3 at time t4, and until time t5 when it becomes smaller than the wheel acceleration V〓wr again, the electromagnetic solenoid for slow/sudden control is turned ON, and the brake hydraulic pressure is is suddenly increased in pressure. When the wheel acceleration begins to decrease and time t5 passes, the electromagnetic solenoid for slow/sudden control is turned off again, and the wheel speed Vwr becomes the road noise countermeasure standard speed Vsn.
The brake hydraulic pressure is gradually increased until the time t6 when the brake pressure becomes lower, and after the elapse of time t6, the electromagnetic solenoid for increase/decrease control is turned on until the time t7 when the wheel speed Vwr becomes equal to or less than the pressure reduction judgment reference speed Vsh, and the brake pressure is increased. Hydraulic pressure is slowly reduced. And again the wheel speed Vwr is at time t7
When the pressure decreases below the depressurization judgment reference speed Vsh, the electromagnetic solenoid for slow/sudden control is turned ON, and the brake hydraulic pressure is suddenly reduced.Then, the same control as described above is performed, and at time t8, the electromagnetic solenoid for slow/sudden control is turned on. is OFF, the electromagnetic solenoid for increase/decrease control is OFF at time t9, the electromagnetic solenoid for slow/sudden control is ON at time t10, the electromagnetic solenoid for slow/sudden control is OFF at time t11, etc., and the brake is turned off. It is assumed that the oil pressure gradually decreases → slowly increases → rapidly increases → slowly increases, and so on.

As mentioned above, the electromagnetic solenoid for increase/decrease control and the electromagnetic solenoid for slow/sudden control are turned ON at the same time as the start of control is determined at time t1, and the brake hydraulic pressure is suddenly reduced due to the wheel acceleration V〓wr. This is to prevent the output of gradual pressure reduction when the wheel speed Vwr becomes smaller than the standard acceleration until the wheel speed Vwr becomes smaller than the control start criterion Vss, thereby preventing the output of pressure reduction due to road vibration.

In this way, the brake oil pressure is controlled for each wheel speed Vwt, Vwr, Vwl, and each wheel 1, 2,
Hydraulic brake devices 9, 10 provided at 3, 4,
By controlling 11 and 12, wheel lock can be prevented and the vehicle can be stopped within a short braking distance.

The processing operation of the present anti-skid device has been briefly explained above, and next, the main processing according to the present invention will be explained in detail with reference to FIGS. 10 and 11.

FIG. 10 is a flowchart showing the control permission determination process among the processes performed in step 102 shown in FIG. 6 described above.

The ignition switch 41 is turned on and the calculation process shown in FIG. 6 is started, and step 102 is started.
When the process moves to step 401, it is first determined whether the flag Fact is 1 or not. At this point, since it has just been set to Fact=0 by the initialization process performed in step 101 of FIG. , all wheel speeds of right front wheel speed Vwr and left front wheel speed Vwl (hereinafter referred to as total wheel speed Vw) are 10 [Km/h]
It is determined whether the value is greater than or not.

If any one of the total wheel speeds Vw is less than 10 [Km/h], it is determined as "NO" in step 402, and the main control permission determination process is completed, and a control start determination (not shown) is made. After processing, the process moves to step 103 shown in FIG. on the other hand,
If the total wheel speed VW is greater than 10 [Km/h], a determination of ``YES'' is made in step 402, and the process moves to the subsequent step 403.

At this point, ignition switch 41 is
Since this is just after the ON state, the vehicle is generally still in a stopped state or has just started moving, and the total wheel speed VW cannot be greater than 10 [Km/h], so step 402 is performed. The result will be "NO". Then, until the all-wheel speed VW reaches 10 [Km/h] or more due to acceleration, in this control permission determination process, the determination is "NO" in step 401 and step 402, and then the control start determination process (not shown) is performed. The transition will be made.

When all wheel speeds VW become 10 [Km/h] or higher, a determination of "YES" is made in step 402, and in the following step 403, it is determined whether the stop switch 14 is in the ON state, that is, whether the driver has performed a brake operation. It is determined whether the If the driver is not operating the brakes, the stop switch 14 is in the OFF state, so the determination in step 403 is "NO", and the control permission determination process ends.

On the other hand, if the driver is operating the brakes, the stop switch 14 is turned on, a determination of "YES" is made in step 403, and the process proceeds to the subsequent step 404.

In step 404, it is determined whether the system is normal or not based on the system abnormality check performed in step 106 shown in FIG. 6 described above.
If the system is abnormal, the determination in step 404 is ``NO'' and the main control permission determination process is completed, whereas if the system is normal, the determination in step 404 is ``YES'' and the process continues.
Move to 405 processing.

In step 405, the flag Fach is set to 1, the main control permission determination process is completed, a control start determination process (not shown) is executed, and the process moves to step 103 in FIG.

As above, ignition switch 14 is turned on
state, and the arithmetic processing shown in FIG. 6 is started.
All wheel speed VW becomes 10 [Km/h] or more, and the stop switch is turned on by the driver's brake operation.
The process of step 405 is executed only when the system is normal, the flag Fact is set to 1, and control permission is determined.

After the flag Fact is set to 1 and control permission is determined, when the process shifts again to the main control permission determination process, it is determined as "YES" in step 401.
The subsequent process of step 406 will be executed,
In step 406, it is determined whether or not the stop switch is OFF, that is, the stop switch 14 is turned on by the driver's brake operation, and after the determination is ``YES'' in step 403, the driver continues to operate the brake. It is determined whether the

If the brake is not operated by the driver and the stop switch 14 is in the OFF state, a determination of "YES" is made in step 406, and the flag Fact is set to "0" in the subsequent step 407.
After finishing this control permission determination process, the process moves to a control start determination process (not shown).

On the other hand, if the driver is operating the brakes and the stop switch 14 is in the ON state, a determination of "NO" is made in step 406, and the process moves to the following step 408, and then goes to step 104 shown in FIG. 6 described above. The estimated vehicle speed Vsb found in is 0.
[Km/h], that is, whether the vehicle has stopped due to the driver's brake operation. still,
The estimated vehicle speed calculation process in step 104 shown in FIG. 6 will be explained in detail after the main control permission determination process.

The vehicle stopped and the estimated vehicle speed Vsb was 0 [Km/h]
If so, it is determined as ``YES'' in step 408, and in this case as well, the process moves to step 407, the flag Fact is set to ``0'', and the main control permission determination process ends. Speed Vsb
If it is not 0 [Km/h], a determination of "NO" is made in step 408, and a determination is made in the following step 409 as to whether or not there is an abnormality in the system.

The system abnormality determination process performed in step 409 is performed based on the system abnormality check in step 106 shown in FIG. 6, similar to step 404 described above.
The flag Fact is set to "0" and the main control permission process is completed. On the other hand, if the system is normal, it is determined as "NO" in step 409 and the main control permission determination process is ended. Become.

In this way, once the flag Fact is set to 1 and control permission is determined, the stop switch 14 is activated.
When it is in the OFF state, the estimated vehicle speed Vsb is 0.
[Km/h] or when an abnormality occurs in the system, the flag Fact is set to "0" and control permission is canceled.

The flag Fact representing control permission obtained through the control permission determination process as described above is one of the control conditions for anti-skid control, and is also used when performing the estimated vehicle speed calculation process in step 104 shown in FIG. Therefore, depending on whether control is permitted or not, that is, whether the flag Fact is "1" or not,
The wheel speed, which is the reference when determining the vehicle speed Vsb, is switched.

As mentioned above, FIG. 11 is a flowchart showing the estimated vehicle speed calculation process in step 104 in FIG.

When this estimated vehicle speed calculation process is started, first, in step 501, it is determined whether the value of the flag Fact set in the control permission determination process described above is "1".

If the value of the flag Fact is “0”, step
501 is determined as "NO", the process moves to step 502, and the wheel speed (hereinafter referred to as reference wheel speed) Vwo, which is the reference when calculating the estimated vehicle speed Vsb, is determined by the following formula: VWO←MED(Vwr , Vwl, Vwt), it can be found from the intermediate wheel speed of the total wheel speed Vw.

On the other hand, if the value of the flag Fact is "1", it is determined as "YES" in step 501, and step 501 is determined as "YES".
503, and at step 503 the reference wheel speed is set.
Vwo can be found from the maximum wheel speed of all wheel speeds VW using the following formula: Vwo←MAX (Vwr, Vwl, Vwt).

When the reference wheel speed VWO is determined in step 502 or step 503, the process in step 504 is executed, and the estimated vehicle speed Vsb is calculated based on the reference wheel speed Vwo using the following formula: Vsb←MED(Vwo, Vsb+αup・t, Vsb− αdw・t). As mentioned above, the above formula was set to suppress the change in the estimated vehicle speed Vsb to less than the acceleration αup during acceleration and less than the deceleration αdw during deceleration, and the reference wheel speed VWO and the estimated vehicle speed found last time.
Compare the speed (Vsb + αup・t) when accelerating by acceleration αup from Vsb and the speed (Vsb − αdw・t) when decelerating by deceleration αdw from the previously calculated estimated vehicle speed Vsb. , the intermediate speed among these three speeds is set as the estimated vehicle body speed Vsb. And step like this
When the estimated vehicle speed Vsb is calculated in step 504, the steps in FIG. 6 of the estimated vehicle speed calculation process are performed.
After step 104 is completed, the process moves to step 105.

The reference wheel speed VWO when calculating the estimated vehicle speed Vsb by the estimated vehicle speed calculation process as described above is
By setting the maximum wheel speed when control is permitted, and setting the intermediate wheel speed when control is not permitted, an estimated vehicle speed Vsb that approximates the actual vehicle speed can be obtained even when acceleration slip occurs. , therefore, based on the estimated vehicle speed Vsb, the sixth
The various reference speeds determined in step 105 in the figure can be brought closer to the optimal values according to the actual vehicle driving conditions, preventing problems such as over-loosening of the brake system during acceleration slips, and achieving good anti-skid control. becomes possible.

In this embodiment, when switching the reference wheel speed VWO, that is, when switching between the intermediate wheel speed and the maximum wheel speed, the switching is done depending on whether control is permitted or not. In addition to determining whether the stop switch is ON or OFF, it also determines whether all wheel speeds VW (or estimated vehicle speed Vsb) are greater than a set value and whether the system is normal or not, but this is a more precise control. Anti-skid control can be performed if at least a judgment before/after the start of control is provided.

In addition, according to this anti-skid control, even when a tire with a smaller diameter is installed due to a tire blowout, etc., the estimated vehicle speed is calculated from the intermediate wheel speed before starting braking, so the same effect as above can be obtained. Become. For example, if either the left or right drive wheel has a puncture and is replaced with a T-type emergency tire with a smaller diameter, the wheel speed Vwr of the right rolling wheel will be approximately equal to the actual vehicle speed, as shown in Figure 12. This is a large value compared to the wheel speed Vwt and the wheel speed Vwl of the left rolling wheel, but according to this anti-skid control device, before the start of braking, the intermediate wheel speed (in this case,
In order to obtain the estimated vehicle speed Vsb from the wheel speed Vwt of the driving wheel, the estimated vehicle speed is calculated from the conventional maximum wheel speed (in this case, the wheel speed Vwr of the right rolling wheel).
Compared to an anti-skid control device that seeks Vsb′,
Estimated vehicle speed Vsb approximated by actual vehicle speed
As in the case of acceleration slip, for example, the reference speed Vsh, which is set to a value smaller than the estimated vehicle speed Vsb by ΔV, which is the reference for loosening the brakes, can be set to a value suitable for the vehicle's driving condition. This makes it possible to perform good anti-skid control according to the driving conditions of the vehicle.

In the above-mentioned embodiment, when switching the wheel speeds that are candidates when performing the estimated vehicle speed calculation process, that is, when calculating the estimated vehicle speed, the calculation is performed based on the intermediate wheel speed or based on the maximum wheel speed. The switching between calculation based on this control is performed depending on whether or not the permission flag Fact is set to "1" in the control permission determination process shown in FIG. In the permission determination process, the permission flag Fact is set/reset based on the state of the stop switch 14.
When the aforementioned T-type tires are installed and the difference between the maximum wheel speed and the intermediate wheel speed becomes extremely large and the brake is operated slowly, the brake system of the wheel at which the intermediate wheel speed and the minimum wheel speed are set must be loosened quickly. There is a risk of damage if you let it out. Therefore, in order to prevent such a risk, a part of the control permission determination process shown in FIG. 10 is changed,
Rather than setting/resetting the permission flag Fact based on the signal from the stop switch 14,
Minimum wheel speed Vvmin and control start judgment reference speed Vss
The control permission determination process shown in FIG. 13, which is carried out based on the magnitude of , will be described as a second embodiment of the present invention in conjunction with FIGS. 13 and 14.

FIG. 13 shows how to determine whether the stop switch 14 is in the ON state in step 403 shown in FIG.
403'), and the determination of whether the stop switch 14 is in the OFF state in step 406 is deleted, and the other steps 401,
Steps 402, 404, 405, 407, 408, and 409 are the same as the control permission determination process described above.

As shown in Fig. 13, in this embodiment, all wheel speeds are 10 [Km/h] or more, the minimum wheel speed Vwmin is a value smaller than the control start judgment speed standard Vss, and the system is turned off when it is normal. When the permission flag Fact is set to "1" for the first time, and once the permission flag Fact is set to "1", the estimated vehicle speed Vsb becomes 0 [Km/h], or when an abnormality occurs in the system. Allow flag Fact
The value of will be set to "0". Note that the minimum wheel speed Vwmin is the minimum wheel speed among all wheel speeds Vw, and is obtained from the following equation: Vwmin=MlN (Vwr, Vwl, Vwt).

Therefore, as shown in FIG. 14, the permission flag Fact is the control start judgment reference speed Vss where the minimum wheel speed Vwmin (front left wheel speed Vwl in this case) is set to a value smaller than the estimated vehicle speed Vsb by ΔV.
It remains in the "0" state until the time ta becomes smaller,
It is set to "1" for the first time after time ta. Then, the reference wheel speed is switched depending on the value of the permission flag Fact, and the estimated vehicle speed Vsb to be determined is determined based on the intermediate wheel speed up to time ta, and based on the maximum wheel speed after time ta. . In this embodiment, since the control start judgment speed standard is used when making the control permission judgment, the start flag Fact is set in the control start judgment immediately after the permission flag Fact is set to "1".
is set to "1", control permission and control start are determined at the same time, and after time ta, the road noise countermeasure reference speed Vsn and the decompression judgment reference speed Vsh
Various reference speeds such as the following are set, and anti-skid control is started.

Note that step 201 shown in FIG. 7 corresponds to the wheel speed detection means, and steps 502 and 503 shown in FIG.
corresponds to the selection means, and the steps shown in FIG.
504 corresponds to calculation means.

In this way, according to this embodiment, the permission flag Fact
The condition for setting stop switch 1 is
Since the control permission determination reference speed Vss is used instead of ON/OFF in step 4, anti-skid control using gentle braking operation can be performed when tires of different diameters are installed and the required wheel speed difference is extremely large. Malfunctions can be prevented, and good anti-skid control can be performed even without a stop switch.

〔Effect of the invention〕

As described above, according to the estimated vehicle speed calculation device according to the present invention, the estimated vehicle speed is the upper limit speed obtained by adding the speed calculated based on the predetermined acceleration to the estimated vehicle speed calculated last time, and the previous speed. A lower limit speed obtained by subtracting a speed calculated based on a predetermined deceleration from the calculated estimated vehicle speed, and a wheel speed selected by the selection means as a candidate speed for the estimated vehicle speed. It is considered to be an intermediate speed. This prevents the estimated vehicle speed from changing following the incorrect wheel speed,
Estimated vehicle speed can be calculated with high accuracy.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
The figure is a diagram showing the estimated vehicle speed Vsb and the reference speed Vs calculated by the estimated vehicle speed calculation device of the present invention when an acceleration slip occurs. FIG. 3 is a system diagram schematically showing the overall configuration of the anti-skid control device, and FIG.
A block diagram showing the main structure of the actuators 17 to 19 that output brake oil pressure to each wheel in the figure, and FIG. 5 is the electronic control circuit 2 in FIG. 3.
6 is a block diagram showing the circuit configuration of No. 6.
FIG. 7 is a schematic flowchart showing the main arithmetic processing of the microcomputer 35 shown in FIG. 7, and FIG.
FIG. 8 is a flowchart showing the vehicle speed interrupt routine which is similarly processed by the microcomputer 35, FIG. 9 is a diagram showing an example of the operation waveforms of each part of the anti-skid control device, and FIG. 10 is similar to FIG. 11 is a flowchart representing the control permission determination process of step 102 shown in FIG.
104 is a flowchart showing the estimated vehicle speed calculation process, FIG. 12 is a diagram showing the estimated vehicle speed Vsb and reference speed Vs calculated when the tire diameters are different, and FIGS. 13 and 14 are diagrams showing the estimated vehicle speed calculation process of the present invention. 13 is a flowchart showing the control permission determination process of this embodiment, and FIG. 14 is a diagram for explaining the processing operation of this embodiment. 1... Right front wheel, 2... Left front wheel, 3... Right rear wheel, 4... Left rear wheel, 5... Right front wheel speed sensor, 6... Left front wheel speed sensor, 7... Rear wheel speed sensor, 9, 10, 11, 1
2...Hydraulic brake device, 17...Right front wheel actuator, 18...Left front wheel actuator, 19...Rear wheel actuator, 35...Microcomputer,
35a...CPU, 35b...ROM, 35c...RAM,
35d...I/O circuit.

Claims (1)

[Scope of Claims] 1. An estimated vehicle speed calculation device that periodically calculates an estimated vehicle speed based on the wheel speeds of a plurality of wheels, which comprises: wheel speed detection means for detecting a wheel speed; selection means for selecting a wheel speed as a candidate speed for the estimated vehicle body speed from among the wheel speeds of the plurality of wheels detected by the wheel speed detection means; An upper limit speed obtained by adding a speed calculated based on a predetermined acceleration to the previously calculated estimated vehicle speed, and a lower limit obtained by subtracting a speed calculated based on a predetermined deceleration from the previously calculated estimated vehicle speed. The intermediate speed is selected from among the three speeds of the set upper limit speed, lower limit speed, and wheel speed selected by the selection means, and the selected speed is used as the current estimated vehicle body speed. An estimated vehicle speed calculation device comprising: calculation means for setting the speed. 2. The estimated vehicle speed calculation device according to claim 1, wherein the selection means selects an intermediate wheel speed from among the wheel speeds of the plurality of wheels before starting braking. 3. The estimated vehicle speed calculation device according to claim 1, wherein the selection means selects a maximum wheel speed from among the wheel speeds of the plurality of wheels after starting braking.