JPH037646A - Anti-skid type brake device - Google Patents

Abstract

PURPOSE:To secure a braking force when a vehicle is loaded, by delaying the start of anti-skid control until the predetermined conditions are met in the case with insufficient breaking liquid pressure for the rear wheels when the front wheels tend to be locked. CONSTITUTION:An anti-skid control unit 90 is fed with signals from rotation sensors 80, 82, 84, 86 for the front and rear, left and right wheels, and controls electromagnetic control valves 39, 64 of a liquid pressure control device so that the slip rate lies within a proper range when the front wheels 18, 26 tend to be locked. In the case the liquid pressures in wheel cylinders 22, 30 have not attained a certain sufficient level when corresponding front wheels 16, 26 tend to be locked, the start of the anti-skid control is delayed until predetermined conditions are met. Thus the load shift from the rear wheels to the front will increase due to increase in the deceleration of the car body resulting from increase in the rear wheel braking force, followed by increase in the load on the front wheels and also increase in the front wheel braking force, and thus the braking distance when the vehicle is loaded can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is based on the hydraulic pressure of the front wheel cylinder (hereinafter referred to as "front fluid pressure") and the hydraulic pressure of the rear wheel cylinder (hereinafter referred to as "front fluid pressure").
An anti-skid system that controls the ratio between the front and rear infusion pressures (referred to as rear infusion pressure) using a provisioning valve device, and also controls the front and rear infusion pressures through a hydraulic pressure control device that is common to the front and rear wheel cylinders. The present invention relates to a skid type brake device, and particularly relates to a technique for suppressing an increase in braking distance when a vehicle is loaded.

(Prior art) The anti-skid type brake device of the above type is generally (
a) A hydraulic pressure source (for example, a mask cylinder) that generates hydraulic pressure at a height corresponding to the operation of the brake operating member; (b) Two wheel cylinders that operate the brakes of the front and rear wheels of the vehicle, respectively. , (C) The hydraulic pressure source side passage extending from the hydraulic pressure source branches into a front wheel side branch passage and a rear wheel side branch passage, and the tip of each branch road is connected to each of the two wheel cylinders. a liquid passage; (d) a proportioning valve device that is provided in the rear wheel side branch passage and that reduces the hydraulic pressure of the hydraulic pressure source and transmits it to the rear wheel wheel cylinder;
e) A hydraulic pressure control device (for example, an electromagnetic control valve) that is installed in the hydraulic pressure source side passage and controls the hydraulic pressure of the front and rear wheel cylinders.
(f) a rotation sensor that detects the rotational speed of the front wheels;
g) Anti-skid control that determines whether or not the front wheels exhibit a tendency to lock based on the detection results of the rotation sensor, and if so, controls the hydraulic pressure control device so that the slip rate of the front wheels falls within an appropriate range. and a control means for performing the same.

In addition, the provisioning hub device is designed to distribute the pre-infusion pressure and the post-infusion pressure when the front and rear wheels are locked at the same time (
It has a control characteristic that approximates a curve representing the ideal hydraulic pressure distribution (hereinafter referred to as ideal hydraulic pressure distribution) using a polygonal line, and in the event that the hydraulic pressure of the hydraulic pressure source becomes locked, the rear wheels are adjusted to the same level as the front wheels. Or restrained to a height that falls somewhat late? il.

Japanese Unexamined Patent Publication No. 60-85052 describes one embodiment of the above-mentioned anti-skid type brake device for use in four-wheeled vehicles. This is an X-piped brake device that can perform anti-skid control, and the wheel cylinder for the left front wheel and the right rear wheel, and the wheel cylinder for the right front wheel and the left rear wheel, respectively.
Each brake system includes one proportioning valve device and one hydraulic pressure control device.
They are set up individually. In this braking device, the rotation speeds of the left and right front wheels are detected by two front wheel rotation sensors, the rotation speeds of the left and right rear wheels are detected by two rear wheel rotation sensors, and the control means , based on the detection results of the four rotation sensors, it is determined for each brake system whether either the front wheel or the rear wheel belonging to that brake system has shown a tendency to lock, and if so, that brake is The hydraulic pressure control device corresponding to the system is supposed to perform anti-skid control.

In this so-called 4-sensor 2-channel anti-skid type brake system (hereinafter referred to as 4-2 type brake system), the road surface in contact with the wheels has a uniform coefficient of friction μ
On roads, if the wheels show a tendency to lock, the actual hydraulic pressure distribution (hereinafter referred to as actual hydraulic pressure distribution) is usually set so that the front wheels show a tendency to lock before the rear wheels. .

The actual fluid pressure distribution is considered to show a tendency for the post-infusion pressure to be insufficient compared to the ideal fluid pressure distribution. Therefore, on a −-like μ road, anti-skid control is started because the front wheels show a locking tendency, so either the front wheels or the rear wheels belonging to each brake system of the control means shows a locking tendency. The determination as to whether or not the front wheels have a tendency to lock will function as a determination as to whether or not the front wheels have shown a tendency to lock.

[Problem to be solved by the invention]

As is clear from the above description, in the anti-skid brake system of the above type, when the wheels show a tendency to lock on a --like μ road, anti-skid control is started by focusing on the tendency of the front wheels to lock. Anti-skid control is performed on both the front and rear wheels even when the rear wheels do not show any tendency to lock. During anti-skid control, the post-infusion pressure remains at the height at the start of anti-skid control (more precisely , is maintained at a height approximately equal to the height at which the pre-infusion pressure was first started to decrease in the depressurization mode in the anti-skid control.

By the way, one of the above-mentioned blotting valve devices is a proportioning valve device (hereinafter referred to as an NVPV device) whose control characteristics remain unchanged. This NVPV device usually has control characteristics suitable for when the vehicle is empty and only the driver is on board. When the car is empty, the post-infusion pressure is made to be slightly lower than the ideal value. However, the ideal fluid pressure distribution is not always constant and changes depending on the vehicle weight.
As the weight of the vehicle increases, it is inevitable that the difference between the actual value and the ideal value of the post-infusion pressure, that is, the amount of deficiency in the post-infusion pressure increases.

Therefore, in an anti-skid type brake system equipped with an NVPV device, anti-skid control focuses on the front wheels, even though the heavier the vehicle weight, the more margin there is before the rear wheels show a tendency to lock. However, there is a problem in that the braking force of the rear wheels is sacrificed, resulting in insufficient braking force for the entire vehicle, and as a result, the braking distance becomes longer.

In addition, the above NVPV is used for the proportioning valve device.
In addition to the device, there is also a load sensing type proportioning valve device (hereinafter simply referred to as an LSPV device) whose control characteristics change depending on the weight of the vehicle. Therefore, N.V.
If the PV device is replaced with an LSPV device, the tendency for post-infusion pressure to become insufficient due to an increase in vehicle weight can be suppressed. However, this L
Even in an anti-skid type brake device equipped with an SPV device, there is a tendency for the post-infusion pressure to be somewhat insufficient in a region where the hydraulic pressure is high, and in this case as well, the problem of insufficient braking force occurs.

An object of the present invention is to solve the above problem by delaying the start of anti-skid control until the post-infusion pressure reaches a sufficient height and, in any case, a predetermined condition is met. It has been done.

[Means for Solving the Problems] The present invention provides an anti-skid type brake device including the above-mentioned hydraulic pressure source, wheel cylinder liquid passage, proportioning valve device, hydraulic pressure control device two-rotation sensor, and control means, at least the following: If the hydraulic pressure in the rear wheel cylinder has not reached a sufficient level when the front wheels show a tendency to lock, the control means The gist is that a control start delay device is provided to delay the start of anti-skid control.

The aspects of this control start delay device include (a) the rotation sensor for the rear wheels, and (b) when the front wheels exhibit a tendency to lock, the coefficient of friction of the road surface (hereinafter simply referred to as road surface μ) reaches its maximum value. (C) a detection result of the rear wheel rotation sensor; and (C) a detection result of the rear wheel rotation sensor. Rear wheel deceleration is determined based on the determined rear wheel deceleration, and the determined rear wheel deceleration reaches a reference deceleration determined by the reference deceleration determining means or a set deceleration set lower than the reference deceleration based on the reference deceleration. Determine whether or not
Otherwise, the control means may include a delay means for delaying the start of the anti-skid control until the rear wheel deceleration reaches a reference deceleration or a set deceleration.

By the way, the road surface μ, that is, the adhesion coefficient between the wheels and the road surface changes depending on the slip rate S of the wheels in contact with the road surface even if the road surface is the same, as is known from the μ-S curve. In addition, anti-skid control is normally started after the road surface μ reaches its maximum value, and the rotation of the wheels is suppressed so that the road surface μ is maintained at the maximum value, that is, the wheel braking force is maintained at its maximum. control. In other words, in the control start delay device of the above aspect, the determination of whether the rear wheel deceleration has reached or is sufficiently close to the reference deceleration is the determination of whether the post-infusion pressure has reached a sufficient height. Therefore, this determination can also be referred to as determining whether the slip ratio S of the rear wheels is appropriate or determining whether the rear wheel braking force is of sufficient magnitude. Furthermore, in the control start delay device of this aspect, the predetermined condition is satisfied for the rear wheel deceleration to reach or be sufficiently close to the reference deceleration.

Note that when the present invention is applied to a brake device equipped with a rotation sensor for rear wheels for purposes other than determining whether or not a delay is necessary, such as the Type 4-2 brake device, if the control start delay device is configured as described above. , the rear wheel rotation sensor can be effectively used to determine whether or not a delay is necessary.

0 Other aspects of the control start delay device include (a) a load sensor that detects the rear wheel load applied to the rear wheels, and (b) a brake signal generator that issues a brake signal representing the strength of braking desired by the driver. and (C) determine the current actual rear wheel fluid pressure based on the brake signal emitted by the brake signal generating means, and determine the current ideal rear wheel fluid pressure ( In addition to determining the static rear wheel load (that is, the rear wheel load when the vehicle is stopped) and the brake signal issued above (i.e., the ideal rear wheel hydraulic pressure determined by, for example, the hydraulic pressure of the mask cylinder), the actual infusion pressure determined is the ideal rear wheel hydraulic pressure. It is determined whether the rear wheel hydraulic pressure has been reached or sufficiently close to the rear wheel hydraulic pressure, and if not, the control means starts anti-skid control until the actual rear wheel hydraulic pressure reaches or is sufficiently close to the ideal rear wheel hydraulic pressure. and a delay means for delaying. That is, in this aspect, the determination of whether the actual rear infusion pressure has reached or is sufficiently close to the ideal rear wheel hydraulic pressure is the determination of whether the after infusion pressure has reached a sufficient height; The predetermined condition is satisfied if the actual transfusion pressure reaches or is sufficiently close to the ideal rear wheel fluid pressure.

The brake signal generating means may be, for example, an operating force sensor that detects the operating force applied to the brake operating member, or a hydraulic pressure sensor that detects the rear V8 hydraulic pressure.

[Effect]

The anti-skid type brake device according to the present invention is applicable when it is determined that it is necessary to perform anti-skid control because the front wheels have shown a tendency to lock, but the post-infusion pressure at the time of the determination has not reached a sufficient height. That is, if there is enough room to increase the post-infusion pressure before the rear wheels show a tendency to lock, anti-skid control is not started. By delaying the start of anti-skid control, the system waits until the post-infusion pressure is sufficiently increased while allowing the front wheels to have a stronger tendency to lock, and then starts anti-skid control when predetermined conditions are met. do. Anti-skid control is normally started at a certain point when the brake operating force is increasing, that is, when the hydraulic pressure of the hydraulic source is increasing. Therefore, if the start of anti-skid control is delayed, anti-skid control becomes necessary. Both the pre-infusion pressure and the post-infusion pressure are higher at the delayed start time than at the time when it is determined that there is a delay, that is, the start time when there is no delay.

〔Effect of the invention〕

As described above, according to the present invention, anti-skid control is started when the rear infusion pressure is sufficiently increased and the rear wheel braking force is appropriate. In addition to maintaining high power, the increase in rear wheel braking force causes an increase in vehicle deceleration, which increases the load transfer from the rear wheels to the front wheels, increases the front wheel load, and increases the front wheel braking force. As a result, the effect of increasing the braking force of the entire vehicle when the vehicle is loaded and shortening the braking distance can be obtained.

〔supplementary explanation〕

When the present invention is applied to the Type 4-2 brake system, the control start delay device is configured to control the hydraulic pressure of the wheel cylinders of the left and right rear wheels at least when the left and right front wheels in each brake system exhibit a tendency to lock. has not reached a sufficient height, the control means may be configured to delay the start of the anti-skid control until a predetermined condition is satisfied after the left and right front wheels show a tendency to lock. In addition, as mentioned above, this control start delay device
The necessity of delay may be determined based on the comparison result of the deceleration of the front and rear wheels.

However, when applying the present invention to a 4-2 type brake device,
As mentioned above, the control start delay device delays the start of control if it is determined that it is necessary to delay the start of control, regardless of whether the road is a uniform μ road or a split μ road where the left and right friction coefficients are different. If this type is used, there will be a problem that the running stability of the vehicle will be somewhat insufficient on split μ roads.

For example, if the split μ road is Type B, where the coefficient of friction on the left side of the road surface is lower than on the right side, anti-skid control is necessary because the left front wheel shows a tendency to lock first in the left front wheel - right rear wheel system. The front right wheel is determined to be -
In the left rear wheel system, it is determined that anti-skid control is necessary because the left rear wheel shows a tendency to lock first. Therefore, while the start of anti-skid control is delayed for the left front wheel-right rear wheel system, it is not delayed for the right front wheel and left rear wheel system. Therefore, the difference between the sum of the braking forces of the left front wheel and the left rear wheel on the low μ side and the sum of the braking forces of the right front wheel and the right rear wheel on the high μ side increases, and the yaw moment increases. The problem arises that the vehicle tends to spin, resulting in a somewhat insufficient running stability.

As a means of solving this problem, the control start delay device is configured to include (a) split μ road detection means for detecting a split μ road, and (b) when a split μ road is detected by the sprint μ road detection means. The anti-skid control may include a delay prohibiting means for immediately starting the anti-skid control without delaying the start of the anti-skid control even if it is determined that it is necessary to delay the start of the anti-skid control. In this way, it is possible to enjoy the effect of shortening the braking distance on a uniform μ road while suppressing insufficient running stability on a split μ road.

Since the conventional 4-2 type brake device is characterized by being able to suppress the occurrence of a situation in which running stability deteriorates on a split μ road, when applying the present invention to this brake device,
If the control start delay device is configured as described above, the above features will not be impaired.

Additionally, when the present invention is applied to a brake device equipped with a rear wheel rotation sensor, such as a 4-2 type brake device, the control start delay device is delayed based on the comparison result of the deceleration of the front and rear wheels. If the rear wheel rotation sensor is used for anti-skid control and for determining the necessity of delay, the number of parts added for determining the necessity of delay can be reduced. , the effect of reducing equipment costs can be obtained.

Note that the X-piped brake system that can perform anti-skid control is not limited to the 4-sensor 2-channel type described above.
A 2-sensor 2-channel type also exists.

This is equipped with two rotation sensors for the front wheels, but not two rotation sensors for the rear wheels, so if the front wheels show a tendency to lock, there is a possibility that the rear wheels show a tendency to lock. A brake device that performs anti-skid control on both the front and rear wheels by estimating that the
This braking device performs anti-skid control by focusing only on the tendency of the front wheels to lock, regardless of whether the road is a split-μ road or a split-μ road.

The present invention can also be applied to this two-sensor, two-channel anti-skid type brake device.

〔Example〕

Below, 4 sensors 2 for a 4-wheeled passenger car, which is an embodiment of the present invention, will be described.
The channel type anti-skid type brake device will be explained in detail based on the drawings.

In FIG. 2, 10 is a brake pedal as a brake operating member, and this brake pedal 10 operates a mask cylinder 12 as a hydraulic pressure source. The mask cylinder 12 includes two pressurizing chambers 14 and 16 that are independent of each other.
4. Generate the same level of hydraulic pressure in 16. The hydraulic pressure generated in one pressurizing chamber 14 is supplied to a front wheel cylinder 22 and a rear wheel cylinder 24 of brakes provided on the left front wheel 18 and the right rear wheel 20, respectively.

The hydraulic pressure generated in the other pressurizing chamber 16 is applied to a front wheel cylinder 30 and a rear wheel cylinder 32 of the brakes provided on the front right wheel 26 and the rear left wheel 28, respectively.
is supplied to

A main fluid passage 34 is provided that connects the pressurizing chamber 14, the front wheel cylinder 22, and the rear wheel cylinder 24. The main liquid passage 34 extends from the pressurizing chamber 14 and branches into two, and each branched end reaches the front wheel cylinder 22 and the rear wheel cylinder 24. Side passage 36.
They are a front wheel cylinder side passage 37 and a rear wheel cylinder side passage 38.

An electromagnetic control valve 39 is provided in the middle of the mask cylinder side passage 36. In addition, the rear wheel cylinder side passage 3
A provocation valve 40 (hereinafter simply referred to as P■, the same applies to 7 8 in the figure) with constant control characteristics as a proration valve device is provided in the middle of 8 .

Since PV40 is well known, it will be briefly explained. PV40 is slidably fitted within the housing;
A piston receives hydraulic pressure from the mask cylinder 12 side on a first pressure receiving surface, and receives hydraulic pressure from the rear wheel cylinder 24 side on a second pressure receiving surface, which has a larger area than the first pressure receiving surface, and a mask based on the movement of the piston. It is provided with an on-off valve that allows and blocks the flow of brake fluid in both directions between the cylinder 12 side and the wheel cylinder 24 side. PV40
A first hydraulic pressure chamber is provided on the side of the mask cylinder 12 from the on-off valve, and a first hydraulic chamber is provided for applying the hydraulic pressure on the mask cylinder 12 side to the first pressure-receiving surface.
On the 4 side, a second hydraulic pressure chamber is provided for applying hydraulic pressure on the rear wheel cylinder 24 side to the second pressure receiving surface. The piston is biased by biasing means in a direction to open the on-off valve.

In this PV40, when the inlet hydraulic pressure, that is, the hydraulic pressure in the first hydraulic pressure chamber, does not reach the turning point hydraulic pressure determined by the urging means, the on-off valve opens and the first and second hydraulic chambers are mutually connected. communicate with. Therefore, in this communication state, as shown in FIG. 3, the inlet hydraulic pressure and outlet hydraulic pressure of the PV40, that is, the hydraulic pressure in the second hydraulic chamber, become equal, and as the inlet hydraulic pressure increases and decreases, The outlet liquid pressure increases and decreases. When the inlet hydraulic pressure reaches the turning point hydraulic pressure, the piston moves in the direction in which the on-off valve closes against the urging force of the urging means, that is, moves forward to close the on-off valve. However, if the inlet hydraulic pressure becomes even higher, the on-off valve will be opened again, and by opening and closing the on-off valve based on the movement of the piston,
The incoming hydraulic pressure is reduced at a constant rate and supplied to the rear wheel cylinder 24.

The control characteristics of this PV40 are obtained by approximating the curve representing the ideal braking force distribution between the front wheel braking force Ff and the rear wheel braking force Fr when the vehicle is empty by a polygonal line having X bending points (the polygonal line shown in Fig. 4). It is said that When the vehicle becomes locked when the vehicle is empty, the rear wheels 2820 are designed to lock in a little later than the front wheels 1'8.26. Therefore, when a passenger car is loaded with a driver and 90 other passengers, as shown in Figure 5,
The ideal braking force distribution line becomes steeper than when the vehicle is empty, and the difference between the ideal braking force distribution line and the actual braking force distribution line increases, so the rear wheel braking force Fr increases until the rear wheels 28.20 fall into a locked state. This means that the height can be kept to a comfortable level.

An electromagnetic control valve 39 is provided in the mask cylinder side passage 36 in FIG.
A return passage 42 is connected to the tail to bypass the tail. This return passage 42 is provided with a check valve 44 that allows the brake fluid to flow from the wheel cylinder side to the mask cylinder side but prevents the flow in the opposite direction. Be sure to return without delay.

The electromagnetic control valve 39 is connected to the reservoir 5 via a reservoir passage 48.
0 is connected. The electromagnetic control valve 39 is a two-position directional switching valve, and communicates the front wheel cylinder 22 and the rear wheel cylinder 24 with the pressurizing chamber 14, and is in a pressure increasing state to increase the hydraulic pressure in these wheel cylinders 22 and 24. , and can be switched to a reduced pressure state in which the hydraulic pressure is reduced by communicating with the reservoir 50. Wheel cylinder 222
4 is in communication with the reservoir 50, brake fluid discharged from the wheel cylinders 22, 24 is stored in the reservoir 50. The brake fluid stored in the reservoir 50 is pumped up by a pump 52 driven by a motor 51 and supplied to the mask cylinder 12 through a pump passage 56 equipped with a check valve 54.

The left front wheel-right rear wheel system has been described above, but the right front wheel-left rear wheel system is also similar to the main liquid passage 58. Mask cylinder side passage 60. Front wheel cylinder side passage 61. Rear wheel cylinder side passage 62, electromagnetic control valve 64. PV
66, return passage 68 check valve 70. A reservoir passage 72 includes a reservoir 74, a pump 76, a check valve 77, and a pump passage 78.

Furthermore, left and right front wheels 18, 26. The rotation speeds of the left and right rear wheels 28.degree. 20 are detected by rotation sensors 80821 2 84.86, respectively, and the detection signals are supplied to an anti-skid control unit 90. Unit 9o has four rotation sensors 80, 82, 84
．． The speed, acceleration, slip rate, etc. of each wheel are calculated based on the signal from 86, and the speed, acceleration, and slip rate of each wheel are calculated.
Solenoid control valve 39.64 based on acceleration, slip rate, etc.
control.

To give a representative explanation of the left front wheel-right rear wheel system, the electromagnetic control valve 39 is normally in the pressure increasing state shown in FIG. Since the slip rate of one of the wheels increases beyond the appropriate range, the anti-skid control unit 9o switches the electromagnetic control valve 39 to the reduced pressure state shown on the right side in the figure.

Thereby from wheel cylinder 22.24 to reservoir 5
The brake fluid is discharged to zero and the fluid pressure decreases.
Thereafter, the unit 9o performs electromagnetic control by controlling the solenoid of the electromagnetic control valve 39 based on the slip rate of the wheel that exhibits a tendency to lock first among the front wheel 18 and the rear wheel 2o. By switching the valve 39 to the appropriate state of pressure increase or pressure reduction, the hydraulic pressure of the wheel cylinders 22, 24 is controlled within an appropriate range, and the left front wheel 18
, the slip rate of the right rear wheel 20 is maintained within an appropriate range. In this embodiment, the unit control in which the anti-skid control is performed in rapid pressure reduction mode and slow pressure increase mode is repeated multiple times. The slow pressure increase mode is realized by alternately switching the electromagnetic control valve 39 between a pressure increase state and a pressure decrease state at regular intervals. In the left front wheel-right rear wheel system, the electromagnetic control valve 39. The reservoir 50 and the like constitute a hydraulic control device, and in the right front wheel-left rear wheel system, the electromagnetic control valve 64. The reservoir 74 and the like constitute a hydraulic pressure control device.

As shown in FIG. 6, the anti-skid control unit 90 includes a CPU 92. ROM94. It is mainly composed of a personal computer equipped with a RAM 96 and a bus 98 that connects them, and the bus 98 is connected to rotation sensors 80 to 80 through an input interface 100.
86 and a brake switch 104 that detects depression of the brake pedal 10 are connected. Also connected to the bus 98 is an output interface 106 that includes a drive circuit 108.110 1
12 respectively via electromagnetic control valves 39, 64. pump 5
A motor 51 that drives the 2°76 is connected. Further, the ROM 94 stores various control programs including a main routine (not shown) and subroutines shown in the flowcharts of FIGS. 7 and 8.

Next, how the anti-skid control is executed will be explained. First, a brief explanation will be given. Note that only the left front wheel-right rear wheel system will be described, and the description of the right front wheel-left rear wheel system will be omitted.

First, we will explain how anti-skid control is executed when the vehicle is empty. If the depression force of the brake pedal 10 is excessive in relation to the road surface μ, the left front wheel 18 tends to lock up earlier than the right rear wheel 20, and anti-skid occurs for the left front wheel 18 at the time corresponding to point A in FIG. It is determined that control is necessary. Rear wheel braking force F at point A when the vehicle is empty.

is quite close to the ideal value, so if it is determined that it is necessary to perform anti-skid control on the left front wheel 18, anti-skid control is started immediately. As a result, as shown in FIG. 9, the front wheel cylinder 22 of the left front wheel 18
While unit control is repeated in which the fluid pressure (hereinafter simply referred to as pre-infusion pressure) is reduced in the rapid pressure reduction mode and then increased in the slow pressure increase mode, the rear wheel cylinder 2 of the right rear wheel 20
The fluid pressure No. 4 (hereinafter simply referred to as post-infusion pressure) is kept constant at the level of the pre-infusion pressure at the start of the rapid pressure reduction mode.

When anti-skid control is started on asphalt roads, snowy roads, etc., the inlet fluid pressure of PV40 usually exceeds the turning point fluid pressure. The pressure reduction in the hydraulic chamber takes place in a reduced pressure region, ie, in a region where the inlet hydraulic pressure is reduced and transferred to the outlet 5 6 hydraulic pressure. Even if the pressure in the first hydraulic chamber decreases, the area of the second pressure-receiving surface of the piston is larger than the area of the first pressure-receiving surface, so the piston continues to be located at the position where the on-off valve opens. As a result, as shown in FIG. 3, the outlet hydraulic pressure is kept almost constant at the level at which the inlet hydraulic pressure starts to decrease, regardless of the decrease in the inlet hydraulic pressure. and,
When the inlet hydraulic pressure further decreases and becomes approximately equal to the outlet hydraulic pressure, the piston moves in the direction in which the on-off valve is opened while being assisted by the urging means, and the outlet hydraulic pressure decreases together with the inlet hydraulic pressure.

This is the hysteresis mentioned above. During anti-skid control, pre-infusion pressure (PV) on asphalt roads, snowy roads, etc.
Since the inlet fluid pressure of 40 normally fluctuates within the constant range of the outlet fluid pressure, the outlet fluid pressure during anti-skid control, that is, the post-infusion pressure, is the same as the high level at the start of anti-skid control, as shown in Figure 9. It is maintained as such.

On the other hand, if it is determined that it is necessary to perform anti-skid control on the left front wheel 18 during loading, the rear wheel braking force F at the time of this determination, that is, at the time corresponding to point A in FIG. is much lower than the ideal value, so if anti-skid control is started at this point, anti-skid control will be performed in a state where the post-infusion pressure is insufficient, and the braking distance will be extended. Therefore, whether it is loading time or not,
That is, it is determined whether or not the post-infusion pressure is insufficient, and if so, the start of anti-skid control is delayed. This determination is made when the absolute value of the acceleration of the right rear wheel 20 (hereinafter simply referred to as right rear wheel acceleration G, I, l. The same applies to other wheels) is the left wheel when the road surface μ reaches its maximum value. Front wheel acceleration GF
Absolute value of L (hereinafter referred to as reference value G).

This is done by determining whether the product of (i, u) and a positive constant α is reached. The constant α is greater than O and 1
The following values are determined to be such that a sufficiently large rear wheel braking force F can be obtained without causing the right rear wheel 20 to lock even when the vehicle is loaded.

While the start of anti-skid control is delayed, as shown in FIG. As the pre-infusion pressure of 7 8 , that is, the inlet liquid pressure of PV4.0, increases, the outlet liquid pressure, that is, the post-infusion pressure, also increases. Both the pre-infusion pressure and the post-infusion pressure are increased while allowing the front wheels to have a stronger tendency to lock. Note that the dashed-dotted lines in the figure indicate the pre-infusion pressure and the post-infusion pressure, respectively, when the start of anti-skid control is not delayed. While the start of the anti-skid control is delayed, the inlet and outlet hydraulic pressures of the PV 40 continue to rise beyond the front wheel lock limit line, as shown in FIG.

If the rear fluid pressure is increased and the rear wheel braking force Fr increases, the deceleration of the vehicle body increases and the amount of load transfer from the right rear wheel 20 side to the left front wheel 18 side increases, and as a result, the left front wheel The dynamic front wheel load of 18 increases and the front wheel braking force Fr increases. While the start of anti-skid control is delayed, the locking tendency of the front wheels is allowed to progress, so the slip rate of the left front wheel 18 increases, but even if the slip rate increases from the appropriate range, it is small. During this period, the road surface μ remains almost constant.

Therefore, as the dynamic front wheel load increases, the front wheel braking force F increases almost in proportion to it. The front wheel braking force F increases due to the increase in load transfer, whereas the rear wheel braking force F
, increases due to an increase in post-infusion pressure. As a result, as shown in FIG. 5, the intersection of the front wheel braking force F and the rear wheel braking force F1 moves upward from point A along the front wheel lock limit line.

The absolute value of the right rear wheel acceleration GR,l is the reference value G.

Anti-skid control is started when the product of and constant α is reached. Anti-skid control is started at the time corresponding to point B in FIG. 5, and the hydraulic pressure in the mask cylinder 12 is increased to '? ! , the pressure begins to be reduced in the decompression mode. In this case as well, the inlet hydraulic pressure fluctuates within the constant range of the outlet hydraulic pressure, as in the case when the vehicle is empty, so during anti-skid control, the outlet hydraulic pressure is It remains constant at high pressure. Note that the delay time ΔL for starting the anti-skid control is normally about 10 m5.

Next, a case where the road surface μ is different between the left and right sides, that is, a case where the road surface is a split μ road will be explained.

9 0 In this case, regardless of whether the vehicle is empty or loaded, if the front left wheel 18 shows a tendency to lock before the rear right wheel 20, the start of anti-skid control is not delayed and is immediately activated. Anti-skid control is started.

When the left front wheel 1B shows a tendency to lock before the right rear wheel 20 on a split μ road, as shown in FIG. This is the case when it is located.

In this case, if the start of anti-skid control is delayed,
In the right front wheel-left rear wheel system, anti-skid control is started without delay due to the left rear wheel 28 showing a tendency to lock, so the sum of the braking forces of the left front wheel 18 and the left rear wheel 28 is As a result, the sum of the braking forces of the front right wheel 26 and the rear right wheel 20 becomes a little larger, and the yaw moment that turns the passenger car to the left becomes larger, causing a situation where the passenger car becomes more likely to spin. Therefore, in this embodiment, if the current road surface is a split μ road, delaying the start of anti-skid control is prohibited.

The above content will be explained in detail based on flowchart 1.

When the power is turned on, initial settings are performed in the main routine, and processes such as resetting flags are performed. Thereafter, the subroutines shown in FIGS. 7 and 8 are executed at regular intervals.

First, a case where the road surface μ is uniform will be explained.

First, in step 31 (hereinafter abbreviated as S.1; the same applies to other steps) in FIG. 7, it is determined whether the brake pedal 10 is depressed depending on whether the brake switch 104 is ON or not. If the pedal has been pressed and the pedal has not been pressed, a command to reset the flag (represented by F in the figure) is issued in S2, a command to stop the motor 51 is issued in S3, and a command to stop the electromagnetic control valve 3 is issued in S4.
By issuing a command to turn off the solenoid No. 9, the current execution of the subroutine ends.

On the other hand, if the brake pedal 10 is depressed, the flag is set to 0 in S5. It is determined whether or not. Since the flag is currently 0, the determination result is YES, and it is determined in S6 whether or not anti-skid control should be started.

The state of this determination will be explained based on FIG.

First, at 5100, the temporal change rate β of the left front wheel acceleration GFL is a constant −β. It is determined whether or not the value is greater than or equal to the value.

When the left front wheel 18 shows a tendency to lock due to the depression operation of the brake pedal 10, the slip rate of the left front wheel 18 increases and shifts from a stable region to an unstable region. During this transition, the left front wheel acceleration GFL is the 12th
As shown in the example shown in the figure, the state changes from a state of gradual decrease to a state of sudden decrease. Since the time when the slip rate of the left front wheel 18 shifts from the stable region to the unstable region and the time when the road surface μ reaches its maximum value coincide with each other, the magnitude of the left front wheel acceleration GF at that time is the reference value G. , it is said that.

Assuming that the slip rate of the left front wheel 18 is currently in the stable region, the determination result of 5100 is YES, and 3101
The absolute value of the current value of the left front wheel acceleration GFL is stored as the reference value G0.

Thereafter, in 5102, it is determined based on the slip rate of the left front wheel 18 whether or not the left front wheel 18 exhibits a tendency to lock. If it is determined that the right rear wheel 20 does not exhibit a tendency to lock, it is determined in 5103 based on the slip rate of the right front wheel 20 whether or not the right rear wheel 20 exhibits a tendency to lock. If it is determined that the right front wheel 20 is not shown either, the process moves to 82 in FIG.

After that, if it is assumed that the left front wheel 18 begins to show a tendency to lock as the subroutine is executed many times, the slip rate of the left front wheel 18 increases and the left front wheel 18 attempts to deviate from the stable region and enter the unstable region. do.

As a result, the rate of change β of the left front wheel acceleration GFI is a constant β.

becomes smaller, and the determination result of 5100 becomes NO. While the rate of change β is still greater than the constant −β8, the absolute value of the current value of the left front wheel acceleration GFL is the reference value G at each execution of the subroutine 3101.

Since the rate of change β is a constant −β. If the slip ratio of the left front wheel 18 shifts from the stable region to the unstable region, the absolute value of the left front wheel acceleration GFL becomes the reference value G.

3 4 As the execution of the subroutine is repeated, the left front wheel 18 shows a tendency to lock, and if the determination result in 5102 becomes YES, in 5104 the right front wheel speeds r and l change to the left rear wheel. It is determined whether the speed ■ is less than or equal to 1.

When the road surface μ is uniform, the left and right front wheels 1826 tend to lock earlier than the left and right rear wheels 28.20, so the left and right front wheel speed vpt, v, □ is equal to the left and right rear wheel speed VRL+
It cannot be larger than VRR. However, the situation is different when the road surface is a split μ road. As shown in FIG. 11, both the front wheel 18 and the rear wheel 28 on the left side of the vehicle have low μ.
Assuming that both the front wheel 26 and the rear wheel 18 on the right side of the vehicle are located on the high μ side, for the left front wheel-right rear wheel system, the left front wheel 18 is located at the right rear wheel 20, similar to the uniform μ road. However, in the right front wheel-left rear wheel system, the left rear wheel 28 shows a locking tendency earlier than the right front wheel 26.

Therefore, it is determined whether the right front wheel speed ■ is smaller than the left rear wheel speed VRL, and if so, the current road surface is uniform μ
If not, it is determined to be a split μ road. If the current road surface is a split μ road, the determination result of S], 04 is No, and the seventh
Moving to 87 in the figure, if the current road surface is a uniform μ road, 5
The determination result in step 104 is YES, and the process moves to step 8105. Note that before the determination result of 5100 becomes No, 5102
The determination result of 5103 will never be YES.

In 3105, it is determined whether the absolute value of the right rear wheel acceleration GRR is greater than or equal to the product of the reference value G0 and the constant α.

Assuming that there is enough time before the right rear wheel 20 locks, the determination result in 5105 becomes NO, and the process moves to 82 in FIG. 7, indicating that anti-skid control is required for the left front wheel 18 this time. Anti-skid control is not started even though it is determined that this is the case. Thereafter, as the execution of the subroutine is repeated, the slip rate of the right rear wheel 20 increases and the absolute value of the right rear wheel acceleration CRH changes to the reference value G.
Assuming that it is greater than or equal to the product of 0 and the constant α, 5105
The determination result becomes YES, and the process moves to 37 in FIG. 567.

The flag is set to 1 in S7, the motor 51 is activated in S8, and the solenoid of the electromagnetic control valve 39 is controlled in S9. Anti-skid control is started. The electromagnetic control valve 39 is connected to the left front wheel 18 and the right rear wheel 20.
It is controlled based on the slip rate of the wheel that showed a tendency to lock first. Thereafter, it is determined in SIO whether it is necessary to end the anti-skid control. If this is not necessary, the determination result is NO and the current execution of the subroutine ends. After that, the subroutine is executed again, and if it is determined in S5 whether or not the flag is O, since the flag is currently 1 and not 0, the determination result in S5 is NO, and steps 36 to S8 are executed. is bypassed and S9 is executed. After it is determined in S6 that it is necessary to start anti-skid control, S6 is not executed again until it is determined in 310 that it is necessary to end anti-skid control.

If it is necessary to end the anti-skid control, the SIQ determination result becomes YES and the process moves to S2. The flag is reset to 0 in S2, the motor 51 is stopped in S3, and the solenoid of the electromagnetic control valve 39 is turned off in S4, thereby returning the electromagnetic control valve 39 to the pressure increasing state.

In this embodiment, the motor 51 is connected to the pump 52 for the left front wheel-right rear wheel system and the pump "1" for the right front wheel-left rear wheel system.
6, so that even if the anti-skid control for the left front wheel and right rear wheel system is terminated, the motor 51 will not be stopped while the anti-skid control is being performed for other systems. It has become.

In addition, in this embodiment, the left front wheel 18 can be used even on a road surface where the front infusion pressure tends to lock before the front infusion pressure reaches the turning point fluid pressure, that is, on an extremely low μ road where the road surface is extremely low, such as an icy and snowy road. The start of anti-skid control is delayed when the car is
On extremely low μ roads, if the start of anti-skid control is delayed, the tendency of the front left wheel 18 to lock becomes extremely strong, and a situation may occur in which the tendency to lock is not easily resolved. If it is necessary to avoid such a situation, the reference value G. That is, it is determined whether the current road surface is an extremely low μ road from the absolute value of the left front wheel acceleration GFL when the road surface μ reaches its maximum value, and if so, the delay in starting the anti-skid control is prohibited. It is desirable to change the execution content of the subroutine as follows.

As is clear from the above explanation, in this example,
Rotation sensors 80-86. Brake switch 104. Pump 52.76, motor 51. The anti-skid control unit 90 constitutes the control means. Among the control means, 510 of the anti-skid control unit 90 in FIG.
The portion that executes 0,5 IOIS 104 and 5105 and the rotation sensors 84 and 86 constitute a control start delay device. In this embodiment, the rotation sensor 8486 is used both for anti-skid control and for determining whether or not a delay is necessary. Of the control start delay devices, 5100 and 5 of the anti-skid control unit 90 in FIG.
101 constitutes a reference deceleration determining means,
The portion that executes step 5104 constitutes a split μ path detection means and delay prohibition means, and the portion that executes step 5105 constitutes a delay means.

In addition, in the above embodiment, the electromagnetic control valves 39 and 64 constituting the hydraulic pressure control device were supposed to be able to switch only to two states: pressure increase and pressure decrease, but in addition, they were designed to maintain the height of the wheel cylinder hydraulic pressure. An electromagnetic control valve having a holding state may also be used.

Further, in the above embodiment, the case where the present invention is applied to an anti-skid type brake device for a passenger car has been described, but the present invention can also be applied to an anti-skid type brake device for a vehicle other than a passenger car, such as a truck. .

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

9 0 FIG. 1 is a graph showing an example of changes in pre-infusion pressure and post-infusion pressure when anti-skid control is performed in a loaded state in an anti-skid type brake system for a passenger car, which is an embodiment of the present invention. 1 and 2 are system diagrams of the brake device, and FIG. 3 is a graph showing an example of changes in inlet hydraulic pressure and outlet hydraulic pressure in a proportioning valve provided in the brake device. Figure 4 is a graph showing the relationship between the front wheel braking force and rear wheel braking force when the vehicle is empty in the above brake system, and Figure 5 is a graph showing the relationship between the front wheel braking force and rear wheel braking force when the vehicle is loaded. . FIG. 6 is a block diagram showing the configuration of an anti-skid control unit of the brake device. FIGS. 7 and 8 are flowcharts showing a portion of the program stored in the ROM of the computer that is closely related to the present invention. FIG. 9 is a graph showing an example of changes in the pre-infusion pressure and the post-infusion pressure when anti-skid control is performed in the brake device in an empty state. FIG. 10 is a graph showing an example of a change in the inlet hydraulic pressure and the outlet hydraulic pressure of the proportioning valve when anti-skid control is performed in the brake device in a loaded state. FIG. 11 is a diagram for explaining an example of a split μ path. FIG. 12 is a graph showing how the left front wheel acceleration changes when the left front wheel begins to show a tendency to lock in the above brake system. 18: Left front wheel 20: Right rear wheel 22.30: Front wheel cylinder 24.32: Rear wheel cylinder 26: Right front wheel 28: Left rear wheel 34.58: Main liquid passage 39.61 Solenoid control valve 40.66: Pro Beautioning valve 50.71 Reservoir 80.82, 84, 86: Rotation sensor

Claims (1)

[Scope of Claims] A hydraulic pressure source, two wheel cylinders that actuate the brakes of the front and rear wheels of the vehicle, and a hydraulic pressure source side passage extending from the hydraulic pressure source that is connected to a front wheel side branch passage and a rear wheel side branch passage. A liquid passage is provided in the rear wheel side branch passage and a liquid passage in which the tip of each branch passage is connected to each of the two wheel cylinders, and the liquid pressure of the hydraulic pressure source is connected to the rear wheel side branch passage. a proportioning valve device that reduces pressure and transmits it to the wheel cylinders of the rear wheels; a hydraulic pressure control device that is installed in the hydraulic pressure source side passage and controls the hydraulic pressure of the wheel cylinders of the front and rear wheels; and a rotation sensor that detects the rotation sensor, and determines whether or not the front wheel exhibits a tendency to lock based on the detection result of the rotation sensor, and if so, controls the hydraulic pressure so that the slip ratio of the front wheel is within an appropriate range. In the anti-skid type brake device including a control means for performing anti-skid control for controlling the device, at least when the front wheel shows a tendency to lock, the hydraulic pressure in the wheel cylinder of the rear wheel has reached a sufficient height. The anti-skid type brake is characterized in that the control means is provided with a control start delay device that delays the start of the anti-skid control until a predetermined condition is satisfied after the front wheels show a tendency to lock. Device.