JP3289444B2 - Anti-lock control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-lock control device, and more particularly to an anti-lock control during low-speed running.

[0002]

2. Description of the Related Art An anti-lock control device has been widely used in a vehicle, and is generally configured as follows. (A) a hydraulic pressure control device capable of at least increasing and decreasing the hydraulic pressure of a wheel cylinder; (b) a slip-related amount obtaining means for obtaining a slip-related amount related to wheel slip; and (c) the slip-related amount. And a control unit that controls the hydraulic pressure control device based on the slip-related amount acquired by the acquisition unit to maintain wheel slip in an appropriate range.

Conventionally, for example, a wheel acceleration and a wheel slip rate or a slip amount have been used as the slip-related amount. A reference acceleration which is a reference of the control is set in advance, and a reference wheel speed smaller than the vehicle speed by the reference slip rate or the reference slip amount is set, and the wheel acceleration becomes lower than the reference acceleration, and the wheel speed becomes lower than the reference wheel speed. The pressure is reduced when it becomes smaller.

[0004] However, when the decompression start condition is set as described above, the decompression start may be delayed during low-speed running and lock may occur. If the wheel speed is low, when the wheel speed is sharply reduced due to a large slip, the wheel speed tends to be zero, and the wheel is easily locked.

For this reason, it is known that the control means is provided with a low-speed countermeasure means for making the pressure reduction start timing of the hydraulic pressure control device earlier when the running speed of the vehicle is lower than when the running speed of the vehicle is higher. . For example, in the anti-lock control device described in Japanese Patent Application Laid-Open No. 57-932, the wheel acceleration and the slip rate are used as the decompression starting reference at the time of high-speed running, and only the wheel acceleration is used at the time of low-speed running. If the wheel acceleration is lower than the reference acceleration when the wheel speed is lower than the set value, decompression is started regardless of the slip rate, so there is no delay in starting decompression and lock is avoided. Is done.

[0006]

However, in this antilock control device, the reference acceleration, which is a condition for starting depressurization, is set irrespective of the height of the friction coefficient of the road surface. Even if it does n’t happen,
On a low road surface, the start of depressurization may be delayed and locking may occur.

According to the first aspect of the present invention, the anti-lock control can be performed without locking the wheels even when the traveling speed and the road surface friction coefficient are low, and the anti-lock control is not performed excessively. has been made to provide a device as a problem, the invention of claim 2, 請
An object of the present invention is to provide a desirable embodiment of the invention of claim 1 .

[0008]

According to the first aspect of the present invention, there is provided a hydraulic pressure control device as shown in FIG. 2, an antilock control device including (c) a control means 3 and (d) a low-speed coping means 4 is provided with a road surface friction coefficient obtaining means 5 for obtaining a road surface friction coefficient. When the friction coefficient of the road surface is low as well as the low, the first low friction coefficient handling means 6 which makes the pressure reduction start timing of the hydraulic pressure control device 1 earlier than the case of the low speed handling means 4, and only the traveling speed is low If the friction coefficient of the road surface is low, the second low friction coefficient handling means 7 is provided to make the pressure reduction end timing of the hydraulic pressure control device 1 earlier than when the traveling speed of the vehicle is low but the friction coefficient of the road surface is high. The point is that

The decompression start timing may be continuously advanced in accordance with the traveling speed, or at least one threshold value for judging whether the traveling speed is high or low is provided. Depending on whether or not, it may be accelerated stepwise.
The decompression end time may be continuously advanced, and may be
May be.

[0010] The invention of claim 2 is the invention according to claim 1.
In the above, the slip-related amount acquisition means is defined as a slip-related amount.
Also to include means for obtaining a wheel acceleration related quantity relating to the wheel speed related quantity and the wheel accelerations associated with the wheel speed
And, the first low coefficient of friction handling means, when not only the traveling speed is low but also the friction coefficient of the road surface is low, the pressure reduction start timing of the hydraulic control device is further than the case of the low speed handling means. The gist of the invention is to include means for changing the wheel speed related amount and the wheel acceleration related amount so as to make the wheel speed faster.

[0011]

In the antilock control device according to the first aspect of the present invention, when the traveling speed of the vehicle is low and the road surface friction coefficient is high, the pressure reduction is started earlier than at the time of high speed traveling.
When the traveling speed of the vehicle is low and the road surface friction coefficient is low, the pressure reduction is started earlier. Also, the vehicle running speed
Low and the coefficient of friction of the road surface is low,
Ended early. The decompression start timing and decompression end depend on the road surface friction coefficient as well as the vehicle traveling speed.
The end time can be changed.

In the antilock control device according to the second aspect of the present invention, when the running speed of the vehicle is low and the road surface friction coefficient is high, the decompression is started earlier than at the time of high speed running, so that not only the running speed is low but also the running speed is low. , Low road friction coefficient
If this is the case, the wheel speed should be
The related amount and the wheel acceleration related amount are changed.

[0013]

As described above, according to the first aspect of the present invention, even if the running speed of the vehicle is low and the road surface friction coefficient is low, the decompression is started early, so that the wheels are not locked,
The effect of improving running stability at the time of braking is obtained. Also,
Decompression was started early, so decompression started early
That the wheel cylinder pressure is reduced excessively
Is avoided, and the effect of preventing the extension of the braking distance is obtained.
You.

According to the invention of claim 2, the traveling speed of the vehicle
Is low and the road friction coefficient is low,
By changing the wheel acceleration related amount, decompression is quicker.
The wheels are locked well
Thus, the effect of improving running stability during braking can be obtained.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a hydraulic brake device for a four-wheeled vehicle according to an embodiment of the present invention; In FIG. 2, reference numeral 10 denotes a tandem type master cylinder. A brake pedal 14 is connected to the master cylinder 10 via a booster 12. When the brake pedal 14 is depressed, a hydraulic pressure having the same height is applied to two independent pressurizing chambers of the master cylinder 10. appear. Reference numeral 16 denotes a reservoir which is attached to the master cylinder 10 and supplies brake fluid thereto.

The hydraulic pressure generated in each pressurizing chamber of the master cylinder 10 is supplied to the proportioning bypass valve 1
8, right and left front wheels 20, 22 and left and right rear wheels 24, 26
Front wheel cylinders 30, 32 and rear wheel cylinders 34,
36. The hydraulic brake system according to the present embodiment is of a front-rear two-system type. When the front wheel system is normal, the hydraulic pressure supplied to the rear wheel cylinders 34 and 36 is adjusted by the proportioning bypass valve 18 to the front. The pressure is reduced at a fixed ratio with respect to the hydraulic pressure supplied to the wheel cylinders 30 and 32. When the front wheel system fails, the proportioning bypass valve 18 does not reduce the hydraulic pressure supplied to the rear wheel cylinders 34 and 36, and the braking force of the vehicle is secured. Since the front and rear brake systems have the same configuration, hereinafter, those having the same action will be denoted by the same reference numerals, and the front wheel brake system will be representatively described.

In the middle of the main liquid passage connecting the master cylinder 10 and the front wheel cylinders 30, 32, two electromagnetic control valves 40 respectively corresponding to the front wheel cylinders 30, 32 are provided. The liquid passage is divided into a master cylinder side passage 42 and a wheel cylinder side passage 44.

Each of the electromagnetic control valves 40 is a switching valve capable of switching between three states: a pressure increasing state, a holding state, and a pressure reducing state. As shown in FIG. 2, the pressure-increasing state is such that the master cylinder-side passage 42 communicates with each corresponding wheel cylinder-side passage 44, and the corresponding front wheel cylinder 3
This is a state in which the hydraulic pressure of 0.32 is increased. The holding state is
Master cylinder side passage 42, wheel cylinder side passage 4
4 and all the reservoir passages 48 are shut off, and the hydraulic pressures of the corresponding front wheel cylinders 30 and 32 are kept constant. The depressurized state is such that the corresponding wheel cylinder side passages 44 communicate with the common reservoir 50 via the reservoir passages 48, and the brake fluid flows out of the front wheel cylinders 30, 32 to the reservoir 50, thereby causing the front wheel cylinders 30, 30 to communicate with each other. This is a state in which the hydraulic pressure at 32 is reduced.

The brake fluid contained in the reservoir 50 is pumped up by a pump 52. The pump 52 is driven by a motor 54, and the brake fluid in the reservoir 50 is reduced in pulsation by an accumulator 56 while a check valve 58
Is supplied to the master cylinder side passage 42 via the pump passage 60 having A reservoir 50 is provided before and after the pump 52.
A pair of check valves 64 are provided, each having a forward direction in which the brake fluid flows from the reservoir 50 to the accumulator 56.
To prevent backflow.

A bypass passage 70 for bypassing each electromagnetic control valve 40 is connected between the master cylinder side passage 42 and the wheel cylinder side passage 44, and each front wheel cylinder 30 , 32 are each provided with a check valve 72 having a forward direction from the master cylinder 10 side. Therefore, when the depression of the brake pedal 14 is released and the hydraulic pressure of the master cylinder is reduced, the electromagnetic control valve 4 is released from the front wheel cylinders 30 and 32.
The brake fluid is immediately returned to the master cylinder 10 by bypassing 0.

Switching of the electromagnetic control valve 40 is performed by the control device 80.
Done by The control device 80 is mainly composed of a microcomputer, and is supplied with an output signal of a rotation sensor 82 for detecting each rotation speed of the left and right front wheels 20, 22 and the rear wheels 24, 26. The rotation sensor 82 is of a pulse type, and rotates with a wheel and has a rotor having a large number of teeth on the periphery, a coil and a permanent magnet attached to a vehicle body, and a pulse signal of an AC voltage generated in the coil as the rotor rotates. And a waveform shaper that converts the waveform into a waveform. A brake switch 86 that detects depression of the brake pedal 14 is also connected to the control device 80.

The configuration of the control device 80 will be described with reference to FIG. The pulse signal output from the rotation sensor 82 is input to a pulse input unit 90, and is supplied from the pulse input unit 90 to a wheel speed calculation unit 92 to calculate the wheel speed. The calculated wheel speeds are supplied to a wheel acceleration calculator 94, a slip ratio calculator 96, and a vehicle speed calculator 98, and the respective calculators 94, 96, 98 calculate the wheel acceleration, the slip ratio, and the vehicle speed. You.

The wheel acceleration is obtained by subtracting the previously supplied wheel speed from the supplied wheel speed each time the wheel speed is supplied per unit time. Wheel deceleration is a negative acceleration.

The vehicle speed is calculated as follows. Even during non-braking and during braking, until the wheel acceleration of all four wheels exceeds the reference acceleration, the fastest wheel speed among the four wheel speeds is set as the vehicle body speed. After the wheel acceleration of all four wheels exceeds the reference acceleration, the vehicle speed is estimated based on the wheel speed and the vehicle speed estimation acceleration when the wheel acceleration of the fourth wheel exceeds the reference acceleration.

The acceleration for estimating the vehicle speed is set according to the friction coefficient of the road surface. At the start of braking, the reference acceleration is set on the assumption that the road surface has a high coefficient of friction. The pressure is set so as not to be excessively reduced. When the braking is started and the wheel acceleration of the third wheel of the four wheels becomes lower than the reference acceleration, the friction coefficient of the road surface is estimated from the wheel acceleration of the fourth wheel (that is, the vehicle body acceleration). . When the wheel acceleration is low (when the wheel deceleration, which is a negative wheel acceleration, is high), the brake is effective and the road surface friction coefficient is high, and when the wheel acceleration is high (when the wheel deceleration, which is the negative wheel acceleration, is low), It is estimated that the brakes are not working and the road surface friction coefficient is low. Then, the acceleration for estimating the vehicle body speed is set based on the estimated road surface friction coefficient.

If the wheel speed is recovered by the reduction of the wheel cylinder pressure and a wheel exceeding the vehicle speed is generated, the speed of the wheel is set as the vehicle speed. When the wheel acceleration of the third wheel becomes lower than the reference acceleration as in the start of the antilock control, the road surface friction coefficient is estimated from the wheel acceleration of the fourth wheel, and the road surface friction coefficient is changed. For example, the vehicle speed estimation acceleration is corrected.

Since the vehicle speed estimated as described above includes a sudden change, it is smoothed by an appropriate digital filter. The vehicle speed calculator 98 supplies the smoothed vehicle speed to the slip ratio calculator 96. The slip ratio calculation unit 96 calculates the slip ratio of each wheel based on the supplied vehicle speed and the wheel speed of each wheel supplied from the wheel speed calculation unit 92.

The vehicle speed calculated by the vehicle speed calculator 98 is also supplied to a vehicle acceleration calculator 100 to calculate the vehicle acceleration. For each unit time, the vehicle acceleration is obtained by subtracting the vehicle speed supplied earlier from the vehicle speed supplied later. Vehicle acceleration calculation unit 100
The vehicle acceleration calculated in is supplied to a low road friction coefficient determining unit (hereinafter, abbreviated as a low μ determining unit) 102, and a low μ determination is performed. Since the absolute value of the vehicle body acceleration during the antilock control is smaller as the road surface μ is smaller, a low μ determination can be made based on whether the vehicle body acceleration is smaller than the reference vehicle body acceleration. Low μ judgment unit 1
02 creates data representing low μ or data representing high μ.

The vehicle speed calculated by the vehicle speed calculating section 98 is further supplied to a low speed determining section 104. If the vehicle speed is equal to or lower than a threshold value (for example, 20 km / h), it is determined that the vehicle is traveling at a low speed. Data indicating low-speed running is created. If the data is larger than the threshold value, it is determined that the vehicle is running at high speed, and data indicating high-speed running is created.

The low μ determining unit 102 and the low speed determining unit 104
Are used by the reference wheel acceleration setting unit 106 and the reference slip ratio setting unit 108, respectively.

The reference wheel acceleration setting section 106 sets a reference acceleration for antilock control based on the traveling speed and the height of the road surface μ. The first reference acceleration G ₁ smaller than 0 and the second reference acceleration G ₂ larger than 0 are set in advance as the reference accelerations. If the vehicle is traveling at high speed, G ₁ , G ₂ regardless of the height of the road surface μ. Is the reference acceleration. When traveling at low speed and the road surface μ is high,
As shown in the graph of FIG. 3, the setting value Delta] g ₁ is added to the first reference acceleration G _1, together with higher than the first reference acceleration G ₁ first reference acceleration G ₁ 'is set, the second reference acceleration G _The set value Δg ₁ is subtracted from ₂ to obtain a second reference acceleration G ₂
A lower second reference acceleration G ₂ ′ is set. A low speed traveling, and, when the road surface μ is low, the setting value Delta] g ₂ is added to the first reference acceleration G _1, the first reference acceleration G
_A first reference acceleration G ₁ ″ higher than ₁ ′ is set.
Also, the set value Δg ₂ is subtracted from the second reference acceleration G ₂ ,
Second reference acceleration G lower than second reference acceleration G ₂ ′
₂ "is set. In the graph of FIG. 3, the wheel speed and the acceleration are shown as simply changing sinusoidally for easy understanding.

In the reference slip ratio setting section 108,
A reference slip ratio for performing antilock control is set. Two types of reference slip ratios are set in advance, ie, a first slip ratio S ₁ and a second slip ratio S _2. If the vehicle is traveling at a high speed, the first and second reference slip ratios S ₁ and S ₂ are determined. It cannot be changed and is used as a criterion as it is. However, it is in low speed, and, when the road surface μ is high, the first reference slip ratio S ₁ is 'is a second reference slip ratio S ₂ is S ₂ smaller than S _2' S ₁ is greater than S ₁ and Is done. The amount by which the first reference slip rate S ₁ ′ is increased, that is, the difference between the first reference slip rate S ₁ ′ and S _1, and the amount by which the second reference slip rate S ₂ is reduced, that is, the second reference slip rate S ₂ And S ₂ ′ are the same. Moreover, a low speed traveling, and, when the road surface μ is low, the first reference slip ratio S ₁ is 'set to S ₁ "greater than, the second reference slip ratio S _2' S ₁ smaller than S ₂ ″. First reference slip ratio S ₁ ″
It is the same and the difference between the S _1, and the difference between the second reference slip ratio S ₂ and S ₂ ".

The reference wheel acceleration G _{1 and the} like set by the reference wheel acceleration setting section 106 are compared with the actual wheel acceleration V calculated by the wheel acceleration calculating section 94 in the comparing section 110.
Compared with _W ′, data indicating which is higher is created.

Further, the reference slip ratio S ₁ or the like which is set in the reference slip ratio setting unit 108 is compared with the actual slip ratio S _W calculated by the slip ratio calculating unit 96 in the comparison unit 112, either a large Is created.

Based on the data created in these comparing units 110 and 112, the control determining unit 11
At 6, a determination is made as to whether the electromagnetic control valve 40 is to be switched to the increased pressure state, the reduced pressure state, or the holding state. The determination in the control determining unit 116 is performed according to the control mode selection map shown in FIG. First slip ratio S
_{The first} and second slip ratios S ₂ are respectively the vehicle speed V _SO
First reference wheel speed V ₁ lower by ΔV ₁ = S ₁ × V _SO
= V _SO (1-S ₁ ) and a second reference wheel speed V ₂ = V _SO (1-S ₂ ) lower by ΔV ₂ = S ₂ × V _SO .
Therefore, _SW ≦ S ₂ , S ₂ < _SW <S ₁ , _SW ≧ S
Performing the determination of ₁ means that V _W ≧ V ₂ in FIG.
This is the same as the determination of V ₂ > V _W > V ₁ and V _W ≦ V ₁ . If the vehicle is traveling at high speed, the above determination is made. If the vehicle is traveling at low speed and the road surface μ is high, the first and second reference slip rates are changed to S ₁ ′ and S ₂ ′, respectively, and the first reference wheel speed is changed. There V ₁ is smaller than _{V 1 '= V SO (1} -S
Is a ₁ '), the second reference wheel speed V ₂ greater than V
₂ ′ = V _SO (1−S ₂ ′). Also,
When the vehicle is traveling at a low speed and the road surface μ is low, the first and second reference slip rates are changed to S ₁ ″ and S ₂ ″, respectively, and the first reference wheel speed is V ₁ ″ = V, which is lower than V ₁ ′. _SO (1
−S ₁ ″), and the second reference wheel speed is V ₂ ′, which is larger than V ₂ ″ = V _SO (1−S ₂ ″).

Based on the control state determined by the control determining section 116, the electromagnetic control valve control section 118 controls the electromagnetic control valve 4
0, the wheel cylinder pressure increases, decreases,
Although the reference slip ratio (reference wheel speed) and the reference acceleration that determine the control state of the electromagnetic control valve 40 are set based on the traveling speed of the vehicle and the road surface μ, the wheel slip during low-speed traveling is determined. Locks are well avoided.

As shown in FIG. 5, even if the wheel speeds decrease during the middle and high speed running and at the low speed running, the wheel speed does not become zero at the middle and high speed running but becomes zero at the low speed running. Locking is easier at low speeds than at medium and high speeds. Further, as described above, in the present anti-lock control device, the wheel speed is calculated based on the input of the pulse from the rotation sensor 82, and the pulse input interval from the rotation sensor 82 is long at the time of low-speed traveling, Since an error is likely to occur in the detection of the wheel speed, the start of pressure reduction is delayed, and locking may occur.

On a road surface having a high μ, as shown in FIG. 6, while the brake works well and the vehicle speed decreases at a steep gradient, the wheels are less likely to slip and the wheel speed changes at a gentle gradient. The wheels are hard to lock. But,
On a road surface with a low coefficient of friction, as shown in FIG. 7, the braking effect is poor, so that the vehicle body speed decreases at a gentle gradient, whereas the wheels easily slip and the wheel speed changes at a steep gradient. Wheels are easy to lock.

On the other hand, the present antilock control device
The reference wheel acceleration and reference slip rate
Because it is set according to the traveling speed and the height of the road surface μ,
The occurrence of locks is avoided well. At low speeds
Taking the case where the road surface μ is low as an example, the first and second
Slip rate (corresponding to the first and second reference wheel speeds) and
The reference acceleration is S ₁ ″, S_Two ″ (V₁ ″, V
_Two ”), G₁ ″, G_Two ”And the graph in FIG.
As shown in FIG.₁ 
Δt₁Time early first reference acceleration G₁ ″ Yo
Wheel speed is lower than the second reference wheel speed V _Two Is
Δt_Two Time earlier second reference wheel speed V_Two ″ Lower
It becomes. Therefore, the pressure reduction is Δt_Two Time starts early and decreases
Wheel speed and wheel acceleration if pressure is not started early
The degrees change as indicated by the broken lines, and the wheels lock.
On the other hand, even if the traveling speed and
There is no lock.

When the slip ratio is reduced (wheel speed is increased) due to the pressure reduction and the wheel acceleration is increased, the actual wheel acceleration is set because the second reference acceleration G ₂ ″ is set to a value Δg ₂ lower than G _2. V _W ′ quickly becomes larger than the second reference acceleration G ₂ ″. The slip rate (wheel speed)
Since the first slip rate S ₁ ″ is larger than S ₁ (the first reference wheel speed V ₁ ″ is smaller than V ₁ ), the actual slip rate _SW becomes earlier and becomes smaller than the first slip rate S ₁ ″. Therefore, when the traveling speed is low and the road surface μ is low, the decompression is ended earlier because of the earlier start.

As is clear from the above description, in the present embodiment, the electromagnetic control valve 40 constitutes the hydraulic pressure control device 1 and the control determining section 116 constitutes the control means 3. Then, the wheel acceleration calculator 94 and the slip ratio calculator 9
6 constitutes the slip-related amount acquisition means 2 and the low-speed determination section 1
The portion for setting the wheel acceleration and the reference slip rate when the traveling speed of the reference wheel acceleration setting section 106 and the reference slip rate setting section 108 is low and the road surface μ is high constitutes the low-speed coping means 4. Further, the vehicle acceleration calculation unit 100 constitutes the road surface μ obtaining means 5 and the low μ determination unit 102
And low speed determination unit 104, reference wheel acceleration setting unit 10
6 and the portion for setting the first reference wheel acceleration and the second reference slip ratio when the traveling speed and the road surface μ of the reference slip ratio setting section 108 are low constitute the first low μ handling means 6. Further, the low μ determination unit 102 and the low speed determination unit 1
04 and a portion for setting the second reference wheel acceleration and the first reference slip ratio when the traveling speed and the road surface μ of the reference wheel acceleration setting portion 106 and the reference slip ratio setting portion 108 are low constitute the second low μ handling means 7. are doing.

Even if the reference slip ratio and the reference acceleration are set in accordance with the running speed of the vehicle and the level of the road surface μ and the wheel cylinder pressure is controlled, the wheels may still be locked. This is because the road surface μ is small and the wheel speed decreases extremely quickly, so that the start of decompression may not be in time or the start of decompression may be delayed due to the detection error of the rotation sensor 82 as described above. When there is a risk of locking as described above, the control device 120 is configured as shown in FIG.

The control unit 120 includes a pulse input unit 9
A pulse input determination unit 122 that determines the presence or absence of a pulse input from 0 is provided. The pulse input determination unit 122
It is determined that there is no pulse input when there is no pulse input for a set time or longer.

The control deciding section 124 includes the pulse input deciding section 1
If there is a pulse input based on the determination at 22, the control state of the electromagnetic control valve 40 is determined in the same manner as the control determination section 116 of the above-described embodiment. When there is no pulse input, it is determined that the wheels are locked. Then, when the reference wheel acceleration and the reference slip rate are set to values when the traveling speed and the road surface μ are low in the reference wheel acceleration setting section 106 and the reference slip rate setting section 108,
When a pulse is input for the first time from a state where no pulse is input, it is determined that the electromagnetic control valve 40 is to be immediately held.

Normally, as shown in the graph of FIG. 9, the actual wheel acceleration or the actual wheel speed recovers and the electromagnetic control valve 40
The state is set when the reference value for setting the state as the holding state is reached. However, when the traveling speed and the road surface μ are low, the decompression is started earlier, so that when the vehicle is locked, the decompression is completed earlier. When the traveling speed and the road surface μ are low, as described above, the depressurization is started earlier, so that the end is completed earlier. However, when the vehicle is locked, the end is completed earlier, and the extension of the braking distance is avoided.

When a pulse is input for the first time after the wheels are locked, the electromagnetic control valve 40 may be set to a pressure increasing state.

In each of the above embodiments, the increase and decrease of the wheel cylinder pressure during the antilock control are performed with the same gradient.
The slope of at least one of the decreases may be changed. When changing both the increasing and decreasing gradients of the wheel cylinder pressure, for example, in the recirculation type anti-lock control device of the above-described embodiment, the state is switched between a state in which the wheel cylinder communicates with the hydraulic pressure source and a state in which the wheel cylinder communicates with the reservoir. An electromagnetic direction switching valve, and a throttle switching electromagnetic valve provided between the electromagnetic direction switching valve and the wheel cylinder, which can be switched between a state in which the flow rate is reduced and a state in which the flow is not reduced,
The wheel cylinder pressure is rapidly increased, gradually increased, rapidly reduced, and gradually reduced by a combination of switching of these two solenoid valves. When only the increasing gradient of the wheel cylinder pressure can be changed, a throttle switching solenoid valve is provided between the electromagnetic directional switching valve and a hydraulic pressure source such as a master cylinder, and only the decreasing gradient of the wheel cylinder pressure can be changed. In this case, a throttle switching solenoid valve may be provided between the electromagnetic direction switching valve and the reservoir.

The duty of the switching of the electromagnetic directional control valve, which is switched between a state in which the wheel cylinder communicates with the hydraulic pressure source and a state in which the wheel cylinder communicates with the reservoir, is controlled so that the time required to communicate the wheel cylinder with the hydraulic pressure source and the communication with the reservoir. The ramping time may be changed to change the gradient of the wheel cylinder pressure.

Further, in each of the above-described embodiments, the acceleration for estimating the vehicle body speed is set to a value for a high μ road when the vehicle is being braked and the antilock control is not performed during high-speed running. However, it may be set to a value for a low μ road.

In each of the above embodiments, the first and second reference accelerations G ₁ and G ₂ are defined as G ₁ ′, G ₁ ″ and G ₂ ′, G
₂ ″, the common values Δg ₁ , Δg
₂ , the first and second reference accelerations G ₁ ,
G by adjusting the different values for G _{2 1} ', G
_{1 ", G 2 ', G} 2" may be set. The same applies to the first and second reference slip rates.

Further, the start of the antilock control and the control state of the hydraulic pressure control device may be determined only by the wheel acceleration or the slip ratio. Only the wheel acceleration or the slip ratio is used as the slip-related amount. In addition to the wheel acceleration, the slip ratio, and the slip amount,
Any quantity related to wheel slip can be used for control.

Further, in the embodiment shown in FIGS. 8 and 9, when the wheels are locked, the running speed of the vehicle is low, and when the road surface μ is low, the lock is released and the pressure reduction ends simultaneously. Alternatively, even when the traveling speed is low and the road surface μ is high, the pressure reduction may be terminated earlier during locking than when the traveling speed is high.

In each of the above embodiments, when the traveling speed and the road surface μ are low, the start timing and the end timing of the pressure reduction are both advanced, but only the start may be advanced. . For example, in the embodiment shown in FIGS. 1 to 7, only the second reference slip rate and the first reference wheel acceleration are set according to the traveling speed and the road surface μ, and the first reference slip rate and the second reference wheel acceleration It does not change regardless of the speed and the road surface μ.

Further, according to the present invention, a shutoff means such as an electromagnetic open / close valve for shutting off the wheel cylinder from the master cylinder during antilock control is provided, and the volume of the variable volume chamber provided on the wheel cylinder side by the shutoff means is changed. It is also possible to apply the present invention to a so-called positive displacement anti-lock control device that controls the wheel cylinder pressure. In the positive displacement antilock control device, the variable volume chamber and the volume changing means for changing the volume of the variable volume chamber constitute a hydraulic pressure control device. As the volume changing means, a piston forming the movable wall of the variable volume chamber is used. May be moved by an electric motor, or a device in which the hydraulic pressure of a control hydraulic chamber formed on the opposite side of the variable volume chamber with a piston interposed therebetween is controlled by an electromagnetic valve.

In the above-described embodiment, the vehicle acceleration calculating section 100 constitutes the road surface μ obtaining means. However, the vehicle acceleration calculating section 98 determines the vehicle acceleration based on the wheel acceleration obtained for determining the acceleration for estimating the vehicle speed. The road surface μ may be estimated. In this case, the vehicle speed calculation unit 98
The portion for acquiring the wheel acceleration of the vehicle constitutes the road surface μ acquiring means.

In addition, the present invention may be applied to the slip-related amount acquisition means, road surface μ acquisition means, control means, and the like without departing from the scope of the claims, in various modifications and improvements based on the knowledge of those skilled in the art. Can be implemented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a control device of a hydraulic brake device including an antilock control device according to an embodiment common to the first and second aspects of the present invention.

FIG. 2 is a system diagram of the hydraulic brake device.

FIG. 3 is a graph illustrating setting of a reference wheel acceleration and a reference slip ratio in the hydraulic brake device.

FIG. 4 is a diagram showing a control mode selection map provided in a control determining unit of the antilock control device.

FIG. 5 is a graph illustrating that the wheels are easily locked when the vehicle is running at a low speed.

FIG. 6 is a graph illustrating that it is difficult to lock wheels when a road surface has a high friction coefficient.

FIG. 7 is a graph illustrating that wheels are easily locked when a road surface has a low coefficient of friction.

FIG. 8 is a diagram showing a configuration of an antilock control device according to another embodiment common to the first and second aspects.

FIG. 9 is a graph illustrating control when the wheel is locked in the antilock control device shown in FIG. 8;

FIG. 10 is a diagram conceptually showing the configuration of the invention of claim 1 ;

[Explanation of symbols]

 Reference Signs List 20 left front wheel 22 right front wheel 24 left rear wheel 26 right rear wheel 30, 32 front wheel cylinder 34, 36 rear wheel cylinder 40 electromagnetic control valve 80, 120 controller

Claims (2)

(57) [Claims] 1. A hydraulic pressure control device capable of at least increasing and decreasing a hydraulic pressure of a wheel cylinder, a slip-related amount obtaining means for obtaining a slip-related amount related to a wheel slip, and the slip-related amount obtaining means obtaining the slip-related amount. Control means for controlling the hydraulic pressure control device based on the slip-related amount obtained to maintain wheel slip in an appropriate range; provided in the control means, when the vehicle speed is low, the vehicle speed is high. An anti-lock control device including a low-speed countermeasure unit for earliering the decompression start timing of the hydraulic pressure control device as compared with a case, wherein a road surface friction coefficient obtaining unit for obtaining a road surface friction coefficient is provided; Is only low
Not the case a low coefficient of friction of the road surface, a first low friction coefficient address means for more quickly than with the solution under a reduced pressure start timing previous SL low speed addressing means pressure control apparatus, the running speed is low
If the friction coefficient of the road surface is low,
When the vehicle is running at a low speed but the road surface is
Second low friction coefficient countermeasure to make it faster than when friction coefficient is high
And an anti-lock control device. 2. The system according to claim 1, wherein said slip-related amount acquiring means includes:
As the lip related amount, a wheel speed related amount related to the wheel speed and a wheel acceleration related amount related to the wheel acceleration are acquired.
Means, and the first low friction coefficient handling means,
When the traveling speed is low and the coefficient of friction of the road surface is also low, the wheel speed related amount and the wheel speed are set so that the pressure reduction start timing of the hydraulic pressure control device is made earlier than when the low speed coping means is used. Means to change the acceleration-related quantity
The anti-lock control device according to claim 1 including: