JPH09290726A - Gearing vibration determining device and braking force controlling device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an erroneous determination for gearing vibration by determining gearing vibration when wheel acceleration/deceleration in each driving wheel is changed in the predetermined pattern within the predetermined time and a change in this predetermined pattern appears in each driving wheel within the predetermined time. SOLUTION: A gearing vibration determining device is provided with a wheel speed detecting means M1, which detects a wheel speed in each of the plural driving wheels, and a gearing vibration determining means M2 which determines generation of gearing vibration if wheel acceleration/deceleration of each driving wheel is changed in the predetermined pattern within the predetermined time and the predetermined patterned wheel acceleration/deceleration change appears within the predetermined time in each driving wheel. Even if the wheel acceleration/deceleration is changed in the predetermined pattern, this change in the predetermined pattern hardly appears synchronously within the predetermined time, so that gearing vibration, in which the predetermined patterned change appears synchronously, can be determined with high precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration detecting device with a gear and a braking force control device using the same, and is used in a vehicle equipped with an ABS (antilock brake system).
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geared vibration determination device that determines that geared vibration has occurred during control, and a braking force control device using the same.

[0002]

2. Description of the Related Art Conventionally, the braking force during braking is controlled by the road surface condition (for example, dry road surface, wet road surface, frozen road surface, etc.), and the wheels are locked by sudden braking especially on slippery road surfaces. ABS (anti-lock brake system) is used to prevent this. This AB
In S, when the driver brakes and the brake pressure is supplied to each wheel, if each wheel is rotating, the pressure increasing mode or the holding mode is set to increase the braking force of the wheel and immediately before the wheel locks. If so, the pressure reducing mode is set to control so as to prevent the wheels from locking.

During the ABS control described above, vibrations with gears may occur in the drive wheel system. Geared vibration means that the friction coefficient μ of the road surface is low, that is, the road surface resistance to the drive wheels is small on so-called low μ roads, and vibration due to gear backlash of the transmission, twisting of the drive shaft, engine vibration, etc. This is a phenomenon that appears as a vibration of the wheel speed, and is amplified by resonance when synchronized with the increase / decrease change of the brake pressure by the ABS control.

For example, Japanese Patent Laid-Open No. 6-32222 discloses that
When acceleration and deceleration of a predetermined magnitude are alternately detected a predetermined number of times for the driving wheel speed, it is determined that gearing vibration occurs independently for each driving wheel, and if gearing vibration is determined. Describes that the ABS pressure increasing control of the brake pressure is stopped and only the pressure reducing control is executed.

[0005]

During traveling on a rough road surface such as a rough road, the road surface on which each wheel is in contact serves as a vibration source, and the wheel speed of each wheel fluctuates. In some cases, the acceleration and the deceleration of a predetermined magnitude are alternately detected a predetermined number of times at a high speed. In this case, in the conventional device, since each drive wheel is individually determined as described above, there is a possibility that the vibration of the wheel speed caused by traveling on a rough road may be erroneously determined as the gear-incorporated vibration. Therefore, when it is erroneously determined that the vibration is due to the gear entering, the brake pressure is reduced during the ABS control, which causes a problem that the deceleration of the vehicle body is delayed.

[0006] The present invention has been made in view of the above points,
The acceleration / deceleration of each drive wheel changes in a predetermined pattern within a predetermined time, and when the change in this predetermined pattern appears in each drive wheel within a predetermined time, it is judged as a gear-in vibration, thereby making a false determination of gear-in vibration. It is an object of the present invention to provide a geared vibration determination device that prevents the above.

Further, a braking force control device capable of suppressing the deceleration delay of the vehicle body is performed by performing the pressure reduction control of the brake pressure only when the slip ratio at the peak wheel speed of the drive wheels is increasing at the time of the gear entering vibration determination. The purpose is to provide.

[0008]

According to a first aspect of the present invention, as shown in FIG. 1A, a wheel speed detecting means M1 for detecting the wheel speed of each of a plurality of drive wheels, and each of the drive wheels. When the wheel acceleration / deceleration of each drive wheel obtained from the wheel speed changes in a predetermined pattern within a predetermined time, and a change in the predetermined pattern of the wheel acceleration / deceleration appears in each drive wheel within a predetermined time It has a geared vibration determination means M2 that determines that vibration has occurred.

Even if the wheel acceleration / deceleration of each drive wheel changes in a predetermined pattern within a predetermined time during traveling on a rough road, it is extremely rare that the change in the predetermined pattern appears in synchronization within the predetermined time. , It is possible to determine with high accuracy the geared vibration in which the change of the predetermined pattern appears in synchronization.

According to the second aspect of the invention, as shown in FIG. 1B, the braking force control for controlling the braking force of each wheel based on the wheel speed of each of the plurality of wheels and the reference vehicle speed. An apparatus for determining vibration with a gear according to claim 1,
Slip ratio determination means M3 for determining whether the slip ratio at the wheel speed peak of each drive wheel is increasing at the time of gear engagement vibration determination, and the brake pressure of the drive wheel only when it is determined that the slip ratio is increased. And a pressure reduction control means M4 for controlling the pressure reduction.

In this way, the brake pressure is reduced only when it is clear that the brake pressure is too high even if the effect of the gear vibration is removed even if the slip ratio at the wheel speed peak increases. It is possible to prevent the pressure from being excessively reduced and suppress the deceleration delay of the vehicle body.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a block diagram of a diagonal two-system antilock brake system to which the present invention is applied. In the figure, 10 indicates a master cylinder.
The master cylinder 10 is a tandem type in which two independent pressure chambers are arranged in series. This master cylinder 10
Is linked to a brake pedal 14 as a brake operating member via a booster 12, and mechanical pressures equal to each other are applied to the two pressurizing chambers in response to the driver's depression of the brake pedal 14. Cause to.

In one pressurizing chamber of the master cylinder 10,
A hydraulically operated brake cylinder for the left front wheel (hereinafter simply referred to as "brake cylinder") and a brake cylinder for the right rear wheel are connected to each other, and the brake chamber for the right front wheel and the left rear wheel are provided in the other pressurizing chamber. Brake cylinders are connected respectively. The two brake systems extending from each pressurizing chamber of the master cylinder 10 are diagonally configured independently of each other. Hereinafter, only one brake system will be described in detail, and the other brake systems have the same configuration in common, and thus the description thereof will be omitted.

One pressurizing chamber of the master cylinder 10 is connected to a front wheel brake cylinder 22 by a front wheel brake passage 20. A rear wheel brake passage 24 is branched from the middle of the front wheel brake passage 20, and a rear wheel brake cylinder 26 is connected to the tip thereof.

A normally open first opening / closing valve 100 is provided in a portion of the front wheel brake passage 20 closer to the master cylinder 10 than the connecting position of the rear wheel brake passage 24. A return passage 102 that bypasses the first opening / closing valve 100 is also connected to the front wheel brake passage 20, and a check valve 104 is provided in the middle of the return passage 102. The check valve 104 blocks the flow of the brake fluid in the direction from the master cylinder 10 to the front wheel brake cylinder 22, but allows the flow in the opposite direction at a valve opening pressure of substantially 0 or higher. .

A proportioning valve (hereinafter simply referred to as "P valve") 110 is provided in the rear wheel brake passage 24. As shown in FIG. 3, the P-valve 110 has a bottomed cylindrical housing 112. A stepped cylinder bore 118 having a large diameter portion 114 and a small diameter portion 116 is formed in the housing 112, and a stepped valve piston 124 having a large diameter portion 120 and a small diameter portion 122 slides on it. Mating is possible. The valve piston 124 is constantly urged by a spring 126 as an urging means to a non-acting position where the tip end surface of the large diameter portion 120 abuts the bottom surface of the housing 112 on the side of the small diameter portion 116. Cylinder bore 118 and valve piston 124
A cup seal 128 serving as a seal member is disposed between and. The cup seal 128 divides the space inside the cylinder bore 118 into two spaces, and the space on the side of the large diameter portion 114 of the cylinder bore 118 is the input chamber 130,
The space on the side of the small diameter portion 116 is the output chamber 132.
The input chamber 130 is connected to the master cylinder 10, and the output chamber 132 is connected to the rear wheel brake cylinder 26.

The cup seal 128 is a one-way seal portion 13.
4 and a two-way seal part 136. The one-way seal portion 134 is in close contact with the surface of the large diameter portion 114 of the cylinder bore 118 to prevent the flow of the brake fluid in the direction from the input chamber 130 to the output chamber 132, and is separated from the surface of the large diameter portion 114. Allows reverse flow. On the other hand, the bidirectional seal portion 136 moves forward (moves to the right in the figure) from the non-acting position to the acting position.
4 is seated on the shoulder surface between the large diameter portion 120 and the small diameter portion 122 to prevent bidirectional flow between the input chamber 130 and the output chamber 132, and is separated from the shoulder surface and bidirectional. Allow the flow of.

The input chamber 1 of the cup seal 128
A plurality of hemispherical protrusions are formed on the surface facing the valve 30 and the surface facing the output chamber 132 along a circumference concentric with the valve piston 124. Input room 1
The protrusion on the side of 30 prevents the cup seal 128 from completely adhering to the valve piston 124, while the protrusion on the side of the output chamber 132 ensures that the cup seal 128 completely adheres to the shoulder surface of the cylinder bore 118. Prevent.

As shown in FIG. 2, the rear wheel brake passage 24
From the connection position of the P valve 110 of the master cylinder 1
A normally open second on-off valve 140 is connected to the portion on the 0 side. A reservoir passage 142 is connected to a portion of the rear wheel brake passage 24 between the connection position of the second opening / closing valve 140 and the connection position of the P valve 110. The reservoir passage 142 extends from the reservoir 144, and a normally closed third on-off valve 146 is provided in the middle of the reservoir passage 142.

Also from the reservoir 144 is the pump passage 1
48 also extends. A pump 150 for pumping the brake fluid from the reservoir 144 is provided in the middle of the pump passage 148. The pump 150 is a plunger type, which is an example of a type in which the brake fluid is intermittently discharged, and the motor 1
Driven by 52. The brake fluid discharge port of the pump passage 148 is connected to a portion of the rear wheel brake passage 24 closer to the master cylinder 10 than the connection position of the second opening / closing valve 140.

The second opening / closing valve 1 in the rear wheel brake passage 24
A portion between the connection position of 40 and the connection position of the P valve 110 is formed by the return passage 154, and the connection position of the master cylinder 10 in the front wheel brake passage 20 and the first opening / closing valve 100.
Connected to the part between the connection position. A check valve 156 is provided in the return passage 154. Check valve 1
Reference numeral 56 blocks the flow of the brake fluid in the direction from the master cylinder 10 to the rear wheel brake cylinder 26, but allows the flow in the opposite direction at a valve opening pressure of substantially 0 or higher.

The pump passage 1 of the rear wheel brake passage 24
A pressure reducing valve 160 is provided on the master cylinder 10 side from the connection position of 48. The pressure reducing valve 160 is configured such that a first check valve 162 whose valve opening pressure is not substantially 0 and a second check valve 164 whose valve opening pressure is substantially 0 are connected in opposite directions and in parallel. It is said that. In this embodiment,
In the antilock control state, since the hoop 150 is used as a pressure source in principle, the pressure reducing valve 160 includes the first check valve 162 for reducing pressure from the pump 150 to the front wheel brake cylinder 22.
It is arranged so as to function as a check valve that allows the flow of the brake fluid in the direction toward the direction above the set valve opening pressure.

Master cylinder 10, pump 150, front wheel brake cylinder 22 and rear wheel brake cylinder 26
The flow of the brake fluid between the two will be described based on FIG.
It should be noted that the main part of the brake fluid pressure circuit is conceptually shown in this figure ignoring the existence of both the P valve 110 and the normally open second on-off valve 140.

In the present embodiment, in the normal braking state where the pump 150 does not operate, the brake fluid from the master cylinder 10 is supplied to the front wheel brake cylinder 22 via the first opening / closing valve 100, and the first opening / closing valve 100 and Rear wheel brake cylinder 26 through second check valve 164.
Is also supplied. Since the valve opening pressure of the second check valve 164 is substantially 0, the same brake pressure is eventually generated in the front wheel brake cylinder 22 and the rear wheel brake cylinder 26.

On the other hand, when the pump 150 is in operation, the first opening / closing valve 100 is closed, and the brake fluid discharged from the pump 150 is the first check valve 162.
After being supplied to the front wheel brake cylinder 22, the rear wheel brake cylinder 26 is directly supplied.
Since the valve opening pressure of the first check valve 162 is not substantially 0,
Eventually, a pressure lower than the rear wheel brake pressure by the valve opening pressure of the first check valve 162 is supplied to the front wheel brake cylinder 22.

That is, in the normal braking state, the master cylinder 10 functions as a pressure source (represented by "second pressure source" in the figure), and applies equal brake pressure to the front wheel brake cylinder 22 and the rear wheel brake cylinder 26. In the pump operating state, the pump 15 is generated respectively.
0 functions as a pressure source (represented by “first pressure source” in the figure), and the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 are respectively provided with brake pressures such that the front wheel brake pressure is lower than the rear wheel brake pressure. It will be generated.

The first opening / closing valve 100, the second opening / closing valve 140, and the third opening / closing valve 146 described above are as shown in FIG.
Each solenoid is connected to the controller 170. The controller 170 includes a CPU, a ROM,
It is mainly composed of a computer including a RAM and a bus, an A / D converter, a driver, etc., and controls the open / closed states of the open / close valves 100, 140, 146.

The controller 170 is also connected to wheel speed sensors 171, 172, 173, 174 for detecting the wheel speeds of the left and right front wheels and the wheel speeds of the left and right rear wheels, respectively. The signals from the wheel speed sensors 172, 174 are connected to the controller 170. Based on this, the on-off valves 100, 140, 146 are controlled. The wheel speed sensors 171 and 172 correspond to the wheel speed detecting means M1.

The controller 170 is further connected to a warning light 194 provided on the operation panel of the vehicle. The warning light 194 is turned on in order to visually notify the driver that the antilock brake system cannot exhibit the desired performance due to an abnormality in the pressure reducing valve 160.

The controller 170 is also connected to the motor 152 and controls the driving state of the motor 152, that is, the driving state of the pump 150. Pump 150
In principle, the drive is prohibited when the reservoir 144 is empty. It is possible to continue driving for the entire period during the ABS control, but in this embodiment, in order to reduce the operating noise of the pump 150 and the like as much as possible, when there is no brake fluid to be pumped, the pump 150 and the like. Is designed to be stopped.

As a method for detecting the empty state of the reservoir 144, for example, the shaft of the piston 176 that is slidably fitted in the reservoir 144 and is biased by a spring 175 as biasing means. Whether the directional position is detected by a sensor (for example, a proximity switch or the like) to directly detect an empty state, or the current value of the motor 152 is detected to determine whether the load applied to the motor 152 is smaller than a set value. The method of indirectly detecting the empty state can be performed by determining whether or not the continuous operation time of the motor 152 is longer than the set value.

Hereinafter, the on-off valve 1 by the controller 170
The control of 00, 140 and 146 will be described in detail. The controller 170 controls the speed sensors 172, 1 during braking of the vehicle.
Based on the rotation status of each wheel based on the signal from 74 (for example, wheel deceleration, slip amount, slip ratio, etc.), it is determined whether or not each wheel has a locking tendency. On the other hand, on-off valve 1
There are seven types of modes that can be realized by combining the open / closed states of 00, 140, and 146, as shown in the following mode table. In Table 1, O is open, C is closed, M /
C represents a master cylinder.

[0033]

[Table 1] Therefore, the controller 170 (a) makes a pressure reduction request for each of the two brake systems that determines that at least one of the front wheels and the rear wheels has a locking tendency, based on the rotation state of each wheel. Should I give it
It is determined whether a holding request or a pressure increase request should be issued. (B) Next, of the seven types of modes, the mode that matches the hydraulic control request determined for the front wheel and the rear wheel is selected. The current mode is decided, and (c) thereafter, the decided current mode is executed. Therefore, in the ROM, for each wheel, a routine (not shown) for determining a hydraulic pressure control request to be issued to each wheel based on the rotation state thereof, and for each on-off valve 100, 140, 146, Each on-off valve 10 based on the hydraulic pressure control request issued to each wheel.
A routine (not shown) for controlling the ON / OFF state of the solenoids 0, 140, 146 is stored in advance.

The contents of the ABS control will be specifically described below. First, a case will be described in which the front wheel or the rear wheel has a locking tendency first. In this case, it is necessary to first reduce the front wheel brake pressure. However, as is clear from the mode table, there is no mode in which only the front wheel brake pressure is reduced. Therefore, first, the seventh mode, that is, the both-side pressure reducing mode is executed.

In the seventh mode, first, the first on-off valve 1
The solenoid 00 is turned on to close the first opening / closing valve 100, and both the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 are separated from the master cylinder 10. Accordingly, the solenoid of the third on-off valve 146 is turned on.
As a result, the third opening / closing valve 146 is opened, whereby the front wheel brake cylinder 22 obtains the second check valve 164, the normally open second opening / closing valve 140 and the currently opened third opening / closing valve 146, and stores them in the reservoir 144. The brake fluid in the front wheel brake cylinder 22 is communicated with each other, and the brake fluid is discharged into the reservoir 144 to reduce the front wheel brake pressure. On the other hand, with respect to the rear wheel brake cylinder 22, the P valve 110 and the third opening / closing valve 146 in the currently open state are obtained and communicated with the reservoir 144, whereby the rear wheel brake pressure is reduced.
That is, this seventh mode is the "both decompression mode".

As a result of the reduction of the front wheel brake pressure, the locking tendency of the front wheels is eliminated or after the elimination tendency occurs,
This execution of the seventh mode ends, and thereafter, the fourth to seventh modes are selectively executed so as to cancel the locking tendency of the front wheels and the rear wheels.

In the fourth mode, both the first opening / closing valve 100 and the third opening / closing valve 146 are closed, and the second opening / closing valve 140 is opened.
Only opened. Therefore, the brake fluid discharged from the pump 150 obtains the first check valve 162 and is supplied to the front wheel brake cylinder 22. As a result, the front wheel brake pressure is increased, while the second open / close state which is currently open. Valve 140
And the P valve 110 is obtained to obtain the rear wheel brake cylinder 26.
The rear brake pressure is also increased as a result. That is, the fourth mode is the both pressure increasing mode. At this time, the pump 1 is attached to the front wheel brake cylinder 22.
Since the discharge pressure of 50 is reduced and transmitted by the valve opening pressure of the first check valve 162, the pressure reduction control by the ABS control and P
As the original brake pressure distribution that is not affected by both the pressure reduction control by the valve 110, a brake pressure distribution in which the front wheel brake pressure is lower than the rear wheel brake pressure by the valve opening pressure of the first check valve 162 is realized. Will be done. The braking force distribution corresponding to this braking pressure distribution is shown as a second basic distribution line in FIG.

On the other hand, in the fifth mode, the on-off valves 100, 1
Since both 40 and 146 are closed, the front wheel brake pressure is the same as in the fourth mode.
Although the pressure is increased by 50, the rear wheel brake pressure is maintained. That is, this mode is the "front wheel pump pressure increasing / rear wheel holding mode".

In this fifth mode, the pump 150
The brake fluid discharged from the rear wheel brake cylinder 2
6 is not supplied, but is supplied only to the front wheel brake cylinder 27. On the other hand, in the fourth mode, the rear wheel brake cylinder 26 is also supplied. Therefore, in the fifth mode, the pressure increase gradient of the brake pressure becomes steeper than in the fourth mode. That is, as conceptually represented by the graph in FIG. 5, if attention is paid only to changes in the front wheel brake pressure, the fourth mode becomes the slow pressure increasing mode and the fifth mode becomes the rapid pressure increasing mode. Focusing only on the change, the fourth mode is the pressure increasing mode and the fifth mode is the holding mode.

In the sixth mode, the first opening / closing valve 100
Since the second opening / closing valve 140 is closed and only the third opening / closing valve 146 is opened, the front wheel brake pressure is
As in the fourth mode, the pressure is increased by the pump 150, but the rear wheel brake pressure is reduced.
That is, this mode is the "front wheel pump pressure increase / rear wheel pressure decrease mode".

In principle, the first to third modes are not executed during the ABS control of the front wheels. The first to third modes are for opening the first opening / closing valve 100.
This is because during the S control, the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 are separated from the master cylinder 10 to reduce the discharge pressure of the pump 150 and reduce pulsation. However, if it is necessary to increase the front wheel brake pressure or the rear wheel brake pressure after the pump 150 has pumped up all the brake fluid in the reservoir 144 and the reservoir 144 has been emptied, those first to third modes are performed. The brake fluid from the master cylinder 10 is used to increase the front wheel brake pressure or the rear wheel brake pressure.

When the front wheel brake pressure is increased by the pump 150 in the fourth mode or the fifth mode, the check valve 104 functions as a relief valve, so that the front wheel brake pressure becomes higher than the master cylinder pressure. Is prevented. The case where the front wheels first tend to lock has been described above. Next, the case where the rear wheels tend to lock first will be described.

In this case, it is sufficient to reduce only the rear wheel brake pressure first. Therefore, first, the third mode is executed. The first opening / closing valve 100 is kept open, the second opening / closing valve 140 is closed, and the third opening / closing valve 146 is opened. As a result, the front wheel brake pressure is ABS.
The control is not substantially performed and the pressure is increased by the master cylinder 10, while the rear wheel brake pressure is reduced by the third opening / closing valve 146 that is currently open.

After that, the first to seventh modes are selectively executed, but the first to third modes are selectively executed in the period in which the front wheels do not tend to lock. When the ABS control is performed only for the rear wheels, while the front wheels also tend to lock, or the rear wheels cancel the lock tendency and only the front wheels tend to lock, the front wheel is first The ABS control is performed on the front wheels or the rear wheels according to the case where the lock tendency occurs.

The first tendency of the rear wheels to be locked is, for example, when the vehicle is braked on a cross road,
This is the case where the front wheel contacts the portion of the road surface where the friction coefficient is high and the rear wheel contacts the portion where the friction coefficient is low. In this case, for the front wheels, it is desirable to increase the front wheel brake pressure as much as possible within the range where the front wheels are not locked in order to increase the utilization factor of the road surface and shorten the braking distance, while for the rear wheels, the cornering force of the tire can be provided. It is desirable to make the size as large as possible to improve the directional stability of the vehicle. That is, it is desirable that the front wheel brake pressure can be increased without increasing the rear wheel brake pressure or the rear wheel brake pressure can be decreased without reducing the front wheel brake pressure. In the present embodiment, the fifth or sixth mode achieves an increase in the front wheel brake pressure without increasing the rear wheel brake pressure,
Further, in the sixth mode, the rear wheel brake pressure is reduced without reducing the front wheel brake pressure. Therefore, according to the present embodiment, the braking distance is shortened and the directional stability of the vehicle is improved when the vehicle is braked on the straddle road in which the front wheels are in contact with the road surface having a high friction coefficient side and the rear wheels are in contact with the road surface having a low friction coefficient side. Can be compatible with both.

Here, the braking force distribution will be specifically described with reference to the graph shown in FIG. In the normal braking state, when the driver starts stepping on the brake pedal 14, the master cylinder 10 functions as a pressure source instead of the pump 150. Therefore, regardless of the presence of the pressure reducing valve 160, the master cylinder pressure is not reduced. Is transmitted to the front wheel brake cylinder 22. Therefore, the braking force distribution points are plotted from the point 0 to the first basic distribution line and the P valve 11 in the graph.
Move along the first 0 line.

Assuming that the vehicle is currently in an empty state, which is an example of a lightly loaded state, when the state immediately before the front wheels are locked due to an increase in brake operating force, the braking force distribution point is set to point a. Reach Then, in this state, the brake operating force is further increased and the front wheel brake pressure is increased. Therefore, assuming that the front wheel locking tendency becomes excessive and the ABS control is started, the front wheel brake pressure and the rear wheel brake pressure are reduced. The decompression mode is executed for both of them, and as a result, the braking force distribution point moves from the point a to the left side in the graph and reaches the point on the first basic distribution line or the first broken line. This time, assume that point is point b.

After that, assuming that the locking tendency of the front wheels is eliminated and the execution of the pump pressure increasing mode for both the front wheel braking pressure and the rear wheel braking pressure is started, the brake fluid exists in the reservoir 144 around this time. Therefore, the discharge pressure of the pump 150 is reduced by the opening pressure of the first check valve 162 and transmitted to the front wheel brake cylinder 22, and is transmitted to the rear wheel brake cylinder 26 without reducing the pressure. When the discharge of the brake fluid from the pump 150 is started, the front wheel brake pressure is maintained as it is and the front wheel braking force is also maintained until the first check valve 162 is opened. Only the wheel braking force increases. Therefore, the braking force distribution point is the point b in the graph.
From the rear wheel to the positive direction of the braking force coordinate axis, then,
The braking force distribution point reaches the intersection with the second basic distribution line or the second broken line of the P valve 110. The second basic distribution line and the second polygonal line are the first basic distribution line and the first polygonal line, respectively, in the negative direction of the coordinate axis of the front wheel braking force, and the intersection point with the coordinate axis of the rear wheel braking force is the first check line. It is created by translating to a point corresponding to the valve opening pressure of valve 162. This time, it is assumed that the intersection with the second polygonal line is point c. After that, the braking force distribution point rises along the second broken line from the point c in the graph, and reaches the point d which is the intersection with the empty rear wheel lock line. After that, the ABS control is executed so that the rear wheel lock is released.

On the other hand, assuming that the vehicle is currently in the loaded state, which is an example of the heavy loading state, when the state immediately before the front wheels are locked due to an increase in the brake operating force is reached, the braking force is distributed. The point reaches point e. Then, it is assumed that the ABS control is started because the brake operating force is further increased in this state, and as a result, the braking force distribution point moves to the point b.

After that, assuming that the lock tendency of the front wheels is eliminated and the execution of the pump pressure increasing mode is started for both the front wheel brake pressure and the rear wheel brake pressure, the braking force distribution points are the same as in the above case. In the graph, it moves from the point b to the positive direction of the coordinate axis of the rear wheel braking force and reaches the point c. After that, the execution of the pump pressure increasing mode is further continued, and the braking force distribution point rises from the point c in the graph along the second broken line and reaches the point f which is the intersection with the loading front wheel lock line. After that, the anti-lock control is executed so that the front wheel lock is released.

Therefore, in this embodiment, the sum of the front wheel driving force and the rear wheel driving force is compared with the case where the ABS control is performed under the first basic distribution line even during loading. That is, the braking force of the entire vehicle is increased and the braking distance is shortened. Further, according to the present embodiment, as is clear from the graph, in the loaded state, the rear wheel braking pressure, that is, the rear wheel braking force is effectively increased from the light braking area which is the area below the break point of the P valve 110. This is possible, and this also has the effect of reducing the braking distance.

FIG. 7 shows a flowchart of an embodiment of a gear entering vibration determination routine executed by the controller 170. This routine is a part of the main routine, and is repeatedly executed at predetermined time intervals such as 6 msec. In FIG. 7, in step S10, it is determined whether or not the right drive wheel is in the geared vibration determination permission state.

Here, the gear entering vibration determination permission state means
As shown in FIG. 8, the wheels are in the ABS control, and not a step running state (the G gravitational acceleration) wheel acceleration DV _W -10G from ABS control start within a predetermined time of the wheels becomes less, and , Wheel acceleration DV _W > α (α is, for example, 4 G), and within a predetermined time T ₁ from the start of ABS control of the wheel, or within a predetermined time T ₂ from that point, the wheel acceleration DV _W is −. α (α is 4
It is in a state of satisfying the condition that it has become less than G). If the right drive wheel satisfies the condition of FIG. 8, there is a high possibility of gear entering vibration, and therefore the gear entering determination permission state is entered, and the process proceeds to step S20. If not, the process proceeds to step S50.

Under the third condition and the fourth condition in FIG. 8, it is determined that the wheel acceleration DV _W of the drive wheel has changed to less than −α and has changed to + α or more within the predetermined time T ₁ . are doing. In step S20, it is determined in the same manner as in step S10 whether or not the left drive wheel is in the gear entering vibration determination permission state. If the left drive wheel is in the geared vibration determination permission state, the process proceeds to step S30, and if not, the process proceeds to step S50. In the case where a gear engagement vibration determination permission condition at step S10 or S20, the gear engagement vibration determination permission condition persists then the predetermined time T _2. Step S30 In respective right and left drive wheels, it is determined whether or not the timing of a gear engagement vibration determination permission condition is mutually within the predetermined time T _3, the vibration of the left and right driving wheels synchronized if within a predetermined time T ₃ Therefore, it is determined that the vibration is geared vibration, and the geared vibration determination flag 1 is set in step S40. On the other hand, if it is not within the predetermined time T ₃ , it is determined that the vibrations of the left and right drive wheels are not in synchronism with each other, and it is determined that it is not due to geared vibration, for example, due to traveling on a rough road, and the process proceeds to step S50 to set the geared vibration determination flag to 0 To set. Step S40,
Alternatively, S50 is executed to end this processing cycle.
The above steps S10 to S30 correspond to the gear entering vibration determination means M2.

Here, even if the wheel acceleration / deceleration of each drive wheel changes in a predetermined pattern within a predetermined time during traveling on a rough road, it is extremely likely that the change in the predetermined pattern appears in synchronization within the predetermined time. It is rare, and it is possible to determine with high accuracy the gear-vibration in which a change in a predetermined pattern appears in synchronization.

FIG. 9 shows a flow chart of an embodiment of a gear vibration suppression routine executed by the controller 170. This routine follows the process of FIG. 7, for example, 6 msec.
Etc. are repeatedly executed at predetermined time intervals. In FIG.
In step S110, it is determined whether or not ABS control of the left and right drive wheels is being performed. If ABS control is being performed, the process proceeds to step S120, and if ABS control is not being performed, this processing cycle ends.

In step S120, it is determined whether or not the gear engagement vibration determination flag is 1, and if this flag is 1 and gear engagement vibration is occurring, the process proceeds to step S130, and if the gear engagement vibration determination flag is 0. In step S170, normal ABS control is performed and the processing cycle ends. Step S13 corresponding to the slip ratio determining means M3
At 0, it is determined whether or not the slip ratio at the latest peak of wheel speed has increased from the previous peak time. If the slip ratio at the peak time is increasing, the brake pressure is too high, so the step S corresponding to the pressure reducing control means M4.
At 140, pressure reduction control is performed. On the other hand, if the slip ratio at the peak does not increase, the brake pressure will not be too high, so the pressure holding control is performed in step S150.

For example, in the case of front wheel drive, step S140
Then, the front wheel brake pressure is reduced in the seventh mode of Table 1, and in step S150, the front wheel brake pressure is maintained (actually, gradually increased) in the fourth mode. Step S above
Steps 130 to 150 are independently executed by the left and right drive wheels, and then the process proceeds to step S160.

In step S160, the determination of convergence of vibration with gear is performed. This determination is, as shown in FIG. 10, that a predetermined time T ₄ or more has elapsed after the ABS control of the left and right drive wheels has been completed, or the gear entering vibration determination is in progress, or a predetermined time T _{5 has} elapsed from the start of the gear entering vibration control. Elapsed and predetermined time T ₅
The wheel acceleration DV _W <-α of the left or right drive wheel has never been reached, or during the vibration determination (DV _W changed from positive to negative), the DV is determined within a predetermined time T ₆ from the vibration determination. _W
<Not a-.alpha., or wheel acceleration DV _W exceeds the previous wheel acceleration DV _W (n-1), the negative peak value ≧-.alpha. negative peak value is but DV _W of DV _W therebetween Or DV _W is less than DV _W (n-1) and DV
_W but there is a positive peak value of the positive peak value of DV _W <α
It is performed when any one of the six conditions that If it is not determined that the gear vibration is converged, step S1
30 and repeat steps S130 to S160,
When it is determined that the gear vibration is converged, step S170
Then, the normal ABS control is performed to end the processing cycle.

That is, if the gear entering vibration determination is not performed again within the predetermined time T ₄ from the second condition in FIG. 10, the gear entering vibration control is canceled. Under the third condition, DV _W within a predetermined time T ₅ (T ₅ <T ₄ ) from the start of gear engagement control
If is not less than −α, the gear vibration control is canceled, and the DV _W is zero crossed for a predetermined time T _{6 under the} fourth condition.
(T ₆ <T ₅₎ within gear engagement vibration control need not DV _W is less than -α in is released, the negative or positive peak value of DV _W in the fifth or sixth condition absolute value α If it does not exceed the limit, the vibration control with gear is released. The reason why the geared vibration control is released under various conditions is that the braked pressure is reduced and the braking force is reduced in the geared vibration control, so that the braking force is returned to the original as soon as possible. .

Further, the brake pressure is reduced only when it is clear that the slip ratio at the wheel speed peak increases and the brake pressure is too high even if the influence of gear vibration is removed. Excessive decompression can be prevented and the deceleration delay of the vehicle body can be suppressed.

Here, FIG. 11A shows the wheel acceleration DV _WFR of the right drive wheel (front wheel). After the ABS control of the right drive wheel is started at time t ₁ , when DV _WFR > α is _satisfied at time t ₂ , the right drive wheel is in the geared vibration determination permission state. Further, FIG. 11B shows the wheel acceleration DV of the left drive wheel.
Indicates _WFL . After starting the ABS control of the left drive wheel at time t _0, the left driving wheel when a DV _WFL> alpha at time t ₃ becomes gear engagement vibration permitted state, the time t _2, t ₃ during a predetermined time T ₃ If it is within the range, the gear entering vibration determination flag is set to 1.

By the way, FIG. 12 shows the wheel speed and the vehicle body speed of either of the left and right driving wheels. Further, each of A ₀ , ... A ₅ indicates the slip ratio at the peak wheel speed. Time t ₁₀
After the gear entering vibration determination flag is set to 1, the slip ratio A ₀ = A ₁ , so the pressure holding control is performed. Next, at time t ₁₁ , when the slip ratio A ₁ <A ₂ , the pressure reduction control is performed, and because the slip ratio A ₂ <A ₃ , the pressure reduction control is performed until time t ₁₂ . At time t ₁₂ , slip ratio A ₃ > A
_When it becomes ₄ , the holding pressure control is performed thereafter.

[0064]

As described above, the invention according to claim 1 is
Wheel speed detection means for detecting the wheel speed of each of the plurality of drive wheels, and the wheel acceleration / deceleration of each drive wheel obtained from the wheel speed for each drive wheel changes in a predetermined pattern within a predetermined time, and the wheel Gear change vibration determination means for determining the occurrence of gear change vibration when a change in a predetermined pattern of acceleration / deceleration appears in each drive wheel within a predetermined time.

Even when the wheel acceleration / deceleration of each drive wheel changes in a predetermined pattern within a predetermined time during traveling on a rough road, it is extremely rare that the change in the predetermined pattern appears in synchronization within the predetermined time. , It is possible to determine with high accuracy the geared vibration in which the change of the predetermined pattern appears in synchronization.

The invention according to claim 2 is a braking force control device for controlling the braking force of each wheel based on the wheel speed of each of a plurality of wheels and a reference vehicle speed, and the gear according to claim 1 Entrainment vibration determination device, slip ratio determination means for determining whether the slip ratio at the time of peak wheel speed for each drive wheel at the time of gear engagement vibration determination, and only when it is determined that the slip ratio increases And a pressure reduction control means for controlling the brake pressure of the drive wheels.

As described above, the brake pressure is reduced only when it is clear that the brake pressure is too high even when the influence of gear vibration is eliminated because the slip ratio at the wheel speed peak increases. It is possible to prevent the pressure from being excessively reduced and suppress the deceleration delay of the vehicle body.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an antilock brake system.

FIG. 3 is a partial front cross-sectional view showing an enlarged P valve.

FIG. 4 is a hydraulic circuit diagram conceptually showing the flow of brake fluid between a master cylinder, a pump, a front wheel brake cylinder, and a rear wheel brake cylinder.

FIG. 5 is a graph for explaining the difference in characteristics between the fourth mode and the fifth mode executed during the ABS control regarding the front wheel brake pressure and the rear wheel brake pressure.

FIG. 6 is a graph for explaining braking force distribution.

FIG. 7 is a flowchart of a gear entering vibration determination routine.

FIG. 8 is a diagram showing the content of a gear-entry vibration determination permission condition.

FIG. 9 is a flowchart of a gear entering vibration suppression routine.

FIG. 10 is a diagram showing the contents of a geared vibration convergence condition.

FIG. 11 is a graph of wheel acceleration of driving wheels.

FIG. 12 is a graph showing wheel speeds of drive wheels and vehicle speeds.

[Explanation of Codes] 10 master cylinder 22 front wheel brake cylinder 26 rear wheel brake cylinder 160 pressure reducing valve 162 first check valve 164 second check valve 170 controller 171 to 174 wheel speed sensor M1 wheel speed detecting means M2 gear vibration determination Means M3 Slip ratio determination means M4 Pressure reduction control means

Claims (2)

[Claims] 1. Wheel speed detection means for detecting the wheel speed of each of a plurality of drive wheels, and wheel acceleration / deceleration of each drive wheel obtained from the wheel speed for each drive wheel changes in a predetermined pattern within a predetermined time. ,And,
A geared vibration determination device comprising: a geared vibration determination means that determines that geared vibration is generated when a change in a predetermined pattern of the wheel acceleration / deceleration appears in each of the drive wheels within a predetermined time. 2. A braking force control device for controlling a braking force of each wheel based on a wheel speed of each of a plurality of wheels and a reference vehicle speed, and a geared vibration determination device according to claim 1, Slip ratio determining means for determining whether the slip ratio at the wheel speed peak of each drive wheel is increasing at the time of entering vibration determination, and reducing the brake pressure of the drive wheel only when it is determined that the slip ratio is increased. A braking force control device comprising: a pressure reducing control means for controlling.