JP5021959B2 - Brake control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle brake control device capable of holding a braking force applied to a wheel brake of a stopped vehicle.

  By holding the braking force applied to the wheel brakes of the stopped vehicle until after the brake operator is released, it is possible to suppress back-up on the uphill, downhill, sudden start on the flat ground, etc. 2. Description of the Related Art A vehicle brake control device that assists starting is known (for example, see Patent Documents 1 and 2).

  In this vehicle brake control device, a braking force holding means (specifically, a normally open solenoid valve) provided in a flow path leading from a master cylinder, which is a hydraulic pressure source, to a wheel cylinder of a wheel brake is opened and closed. Thus, the braking force is held and released.

  By the way, if the braking force is released before the vehicle starts, a rearward movement or the like of the vehicle occurs. Conversely, if the braking force is maintained until the vehicle starts, the vehicle starts smoothly. Therefore, it is necessary to appropriately set the timing for releasing the braking force.

  For example, in the vehicle brake control device disclosed in Patent Document 3, paying attention to the negative rate of change of the engine speed when the clutch is connected, the actual rate of change of the engine speed is the accelerator pedal. The braking force is released when the change rate falls below the reference change rate defined according to the amount of depression of the vehicle, thereby achieving both suppression of rearward slipping and smooth start.

JP 2004-182219 A JP 2000-190828 A Japanese Examined Patent Publication No. 5-84259

  The vehicle brake control device of Patent Document 3 has a problem that it is difficult to determine the timing for releasing the braking force when the rate of change of the engine speed is small, such as when a so-called half-clutch operation is performed. If the timing for releasing the braking force is inappropriate, backlash will occur or the feeling of acceleration will be hindered.

  From such a point of view, the present invention is a vehicle brake control device capable of holding a braking force applied to a wheel brake of a stopped vehicle, in which the rate of change in engine speed is small. It is another object of the present invention to provide a vehicle brake control device that can release a braking force at an appropriate timing.

The present invention for solving such a problem estimates a braking force holding means for holding a braking force applied to a wheel brake of a stopped vehicle and an engine speed at no load corresponding to an actual accelerator opening. Deviation is obtained by subtracting the actual engine speed when the load from the clutch is applied to the engine from the engine speed at no load estimated by the engine speed estimation means and the engine speed estimation means. a deviation calculating means for calculating, the accelerator opening acquisition section for acquiring the accelerator pedal operation amount that correlates to the accelerator opening, so that the release reference value the larger the value of the accelerator pedal operation amount that correlates to the accelerator opening increases and removing reference value storage means for storing the correlation Do, the solution releasing reference value corresponding to the accelerator pedal operation amount acquired by the accelerator opening acquisition section Cancellation reference value search means for searching from reference value storage means, and determination means for determining whether or not the deviation calculated by the deviation calculation means is greater than or equal to the release reference value searched for by the cancellation reference value search means And the braking force holding means releases the braking force when the determination means determines that the deviation is greater than or equal to the release reference value. To do.

  In short, the present invention is characterized in that the braking force is released when the deviation between the no-load engine speed corresponding to the actual accelerator opening and the actual engine speed exceeds a release reference value. .

The “actual engine speed” is the engine speed at which the vehicle is started. When the transmission is in a position other than the neutral position and the clutch transmits power, the load on the clutch side is applied to the engine. This means the engine speed when the engine is engaged. The "engine speed when there is no load" means that the clutch is not transmitting power and the engine is not loaded with the clutch ( For example, it means the engine speed when the transmission is in the neutral position. The “engine” in the present invention includes not only an internal combustion engine but also an electric motor .

If the accelerator opening is the same, the actual engine speed will be less than the engine speed when there is no load, so by monitoring the deviation, whether or not the driver is going to start the vehicle. It becomes possible to determine. If the necessity of braking force is determined based on whether or not the deviation between the engine speed at no load and the actual engine speed is equal to or greater than the release reference value, Even when the rate of change of the engine speed remains small, or even when the engine speed changes irregularly due to factors other than the accelerator operation, the timing for releasing the braking force can be mistaken. Therefore, it is possible to obtain a good acceleration feeling while preventing rearward slipping of the vehicle.
In addition, in the present invention, the release reference value for determining whether or not the braking force is necessary is set according to the accelerator opening, so that the braking force can be released at a more appropriate timing.

The vehicle brake control device described above may be provided with an engine speed storage means for storing the correlation between the accelerator pedal operation amount correlated with the accelerator opening and the engine speed when there is no load. In this case, the engine speed estimation means corresponds to the actual accelerator opening by searching the engine speed storage means using the accelerator pedal operation amount acquired by the accelerator opening acquisition means as a search key. Estimate the engine speed when there is no load. In this way, it is possible to easily and reliably estimate the engine speed at no load corresponding to the actual accelerator opening.

  According to the vehicle brake control device of the present invention, the braking force applied to the wheel brake of the stopped vehicle can be released at an appropriate timing.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  As shown in FIG. 1, the vehicle brake control device U according to the present embodiment correlates with various components such as a solenoid valve and a pump, a hydraulic pressure unit 10 provided with a brake fluid flow path, and the accelerator opening. Accelerator opening degree acquisition means 20 for acquiring accelerator opening degree information, engine speed acquisition means 30 for acquiring engine speed, and a control unit 40 for controlling various components of the hydraulic unit 10 are provided. In addition to maintaining the braking force applied to the wheel brakes of the stopped vehicle, it suppresses wheel slips according to the vehicle behavior, road surface conditions, brake operating condition, etc., and further, anti-lock brake control, Carry out skid control to stabilize the behavior of the vehicle.

  The hydraulic unit 10 is interposed between a master cylinder M that is a hydraulic source and a wheel cylinder W of the wheel brake BR, and two wheel brakes of the four wheel brakes BR, BR,. A brake system K1 for applying braking force to BR and BR and a brake system K2 for applying braking force to the remaining two wheel brakes BR and BR are provided.

  The master cylinder M generates a hydraulic pressure corresponding to the pedaling force applied to the brake pedal L as a brake operator, and includes two output ports M1 and M2 corresponding to the two brake systems K1 and K2. ing.

  Since the brake systems K1 and K2 have substantially the same configuration, the brake system K1 will be mainly described below, and the brake system K2 will be described as appropriate.

  The brake system K1 is provided with a regulator R, a control valve means V, a suction valve 4, a reservoir 5, a pump 6, a damper 7, an orifice 7a, and a hydraulic pressure sensor 8.

  In the following description, the flow path (oil path) from the output port M1 of the master cylinder M to the regulator R out of the flow paths connecting the master cylinder M and the wheel cylinder W is referred to as “output hydraulic pressure path A”. A flow path from the regulator R to the wheel cylinder W is referred to as “wheel hydraulic pressure path B”. Of the flow paths bypassing the regulator R, the flow path from the output hydraulic pressure path A to the pump 6 is referred to as “suction hydraulic pressure path C”, and the flow path from the pump 6 to the wheel hydraulic pressure path B is “discharge”. This is referred to as “hydraulic path D”. A flow path from the wheel hydraulic pressure path B to the suction hydraulic pressure path C is referred to as “open path E”.

  The regulator R has a function of switching between a state where the brake fluid is allowed to flow from the output hydraulic pressure passage A to the wheel hydraulic pressure passage B and a state where the brake fluid is blocked, and a brake fluid flow from the output hydraulic pressure passage A to the wheel hydraulic pressure passage B. It has a function of adjusting the brake fluid pressure in the wheel fluid pressure passage B and the discharge fluid pressure passage D to a set value or less when the inflow is interrupted, and the cut valve 1, the check valve 1a and the relief valve 1b are provided. It is prepared for.

  The cut valve 1 is a normally open electromagnetic valve interposed between the output hydraulic pressure path A and the wheel hydraulic pressure path B, and from the master cylinder M side to the wheel cylinder W side when in the valve open state. The brake fluid is allowed to flow in and shut off when the valve is closed. The normally open type electromagnetic valve constituting the cut valve 1 has an electromagnetic coil for driving the valve body electrically connected to the control unit 40, and the electromagnetic coil is excited based on a command from the control unit 40. Then, the valve is closed, and when it is demagnetized, the valve is opened. In the present embodiment, the cut valve 1 functions as a braking force holding unit that holds the braking force applied to the wheel brake of the stopped vehicle.

  The check valve 1 a is a valve that allows only brake fluid to flow from the master cylinder M side to the wheel cylinder W side, and is connected in parallel to the cut valve 1.

  The relief valve 1b is connected in parallel to the cut valve 1, and opens when the value obtained by subtracting the brake hydraulic pressure in the output hydraulic pressure path A from the brake hydraulic pressure in the wheel hydraulic pressure path B exceeds a set value, The inflow of the brake fluid from the hydraulic pressure path B to the output hydraulic pressure path A is allowed.

  The control valve means V is provided at the intersection of the wheel hydraulic pressure path B and the open path E, and is in a pressure-increasing state that blocks the open path E while opening the wheel hydraulic pressure path B. It has a function of switching between a reduced pressure state in which the open path E is opened while blocking and a holding state in which the wheel hydraulic pressure path B and the open path E are blocked. That is, the control valve means V switches between a state in which the brake fluid pressure acting on the wheel cylinder W is increased, a state in which the brake fluid pressure is reduced, and a state in which the brake fluid pressure is maintained. The control valve means V according to this embodiment includes an inlet valve 2, a check valve 2a, and an outlet valve 3.

  The inlet valve 2 is a normally open solenoid valve provided in the wheel hydraulic pressure passage B, and allows the brake fluid to flow from the master cylinder M side to the wheel cylinder W side when the valve is open, and is closed. Shut off when in valve state. The normally open electromagnetic valve constituting the inlet valve 2 has an electromagnetic coil for driving the valve body electrically connected to the control unit 40, and the electromagnetic coil is excited based on a command from the control unit 40. Then, the valve is closed, and when the electromagnetic coil is demagnetized, the valve is opened.

  The check valve 2 a is a valve that allows only brake fluid to flow from the wheel cylinder W side to the master cylinder M side, and is connected in parallel to each inlet valve 2.

  The outlet valve 3 is a normally closed electromagnetic valve interposed between the wheel hydraulic pressure passage B and the release passage E, and brake fluid from the wheel cylinder W side to the reservoir 5 side when the valve is closed. Inflow is blocked and allowed when the valve is open. The normally closed electromagnetic valve constituting the outlet valve 3 has an electromagnetic coil for driving the valve body electrically connected to the control unit 40, and the electromagnetic coil is excited based on a command from the control unit 40. Then, the valve is opened, and when the electromagnetic coil is demagnetized, the valve is closed.

  The suction valve 4 is a normally closed electromagnetic valve provided in a flow path (suction fluid pressure path C) that bypasses the cut valve 1 and communicates between the master cylinder M and the suction side of the pump 6. Then, the state in which the suction fluid pressure path C is opened and the state in which it is shut off are switched. The normally closed electromagnetic valve constituting the intake valve 4 is configured such that an electromagnetic coil for driving the valve body is electrically connected to the control unit 40, and the electromagnetic coil is excited based on a command from the control unit 40. Then, the valve is opened, and when the electromagnetic coil is demagnetized, the valve is closed.

  The reservoir 5 is provided in the release path E, and has a function of temporarily storing brake fluid released through the control valve means V. Further, between the reservoir 5 and the pump 6, a check valve 5 a that allows only brake fluid to flow from the reservoir 5 side to the pump 6 side is interposed.

  The pump 6 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and is driven by the rotational force of the motor 9 described later. The brake fluid temporarily stored in the reservoir 5 is sucked and discharged to the discharge hydraulic pressure path D. Thereby, the pressure state of the output hydraulic pressure path A and the wheel hydraulic pressure path B reduced by storing the brake fluid in the reservoir 5 is recovered. When the cut valve 1 is in the closed state and the intake valve 4 is in the open state, the pump 6 sucks the brake fluid on the master cylinder M side and discharges it to the discharge hydraulic pressure path D. As a result, the brake fluid pressure generated by operating the brake pedal L can be increased, and further, the brake fluid pressure can be applied to the wheel cylinder W even when the brake pedal L is not operated. .

  The damper 7 and the orifice 7a attenuate the pulsation of the brake fluid discharged from the pump 6 by the cooperative action.

  The hydraulic pressure sensor 8 measures the magnitude of the brake hydraulic pressure in the output hydraulic pressure path A (that is, the brake hydraulic pressure of the master cylinder M), and the measurement result is taken into the control unit 40 as needed. 40 determines whether or not the brake fluid pressure is output from the master cylinder M, that is, whether or not the brake pedal L is depressed, and further determines the magnitude of the brake fluid pressure measured by the fluid pressure sensor 8. Based on this, holding control and behavior stabilization control, which will be described later, are executed.

  The motor 9 is a common power source for the pumps 6 and 6 in the brake systems K1 and K2 and operates based on a command from the control unit 40.

  The accelerator opening acquisition means 20 acquires accelerator opening information correlated with the accelerator opening. For example, an accelerator position sensor (accelerator opening) that detects an operation amount (depression amount) of an accelerator pedal that is an accelerator operator. Degree sensor). In the present embodiment, the case where the accelerator position sensor is the accelerator opening degree acquisition means 20 is illustrated, but the type of the accelerator opening degree acquisition means 20 is not limited. For example, a throttle sensor that detects the opening (opening / closing amount) of the throttle valve may be used as the accelerator opening acquiring means 20, and a sensor that detects the flap opening, a sensor that detects the intake air amount, and the like may be used. It does not matter.

  The engine speed acquisition means 30 acquires the actual engine speed, and includes, for example, a speed detection sensor that detects the speed of the output shaft (crankshaft) of the engine.

  The control unit 40 includes an output from a wheel speed sensor S attached to each of the four wheels, an output from the hydraulic pressure sensor 8, an output from the accelerator opening acquisition means 20, an output from the engine speed acquisition means 30, and the like. Based on the control, regulator R (cut valve 1), control valve means V (inlet valve 2, outlet valve 3), intake valve 4, motor 9 and the like are controlled, and the control applied to the wheel brake of the stopped vehicle is performed. In addition to executing holding control to hold power, anti-lock brake control that suppresses wheel slip according to vehicle behavior, road surface condition, brake operating condition, etc., skid control to stabilize vehicle behavior, etc. Execute.

  Although not shown, the control unit 40 includes a central processing unit (CPU), a RAM, a ROM, and an input / output circuit. The control unit 40 includes inputs from various sensors, control programs stored in the ROM, and various threshold values (releases). As shown in FIG. 2, the engine speed storage means 41, the engine speed estimation means 42, the deviation calculation means 43, the release reference value storage means 44, the release reference are performed by performing various arithmetic processes based on the reference value) and the like. It functions as a value search unit 45, a determination unit 46, and a holding control unit 47.

  The engine speed storage means 41 stores a correlation between accelerator opening information correlated with the accelerator opening and the engine speed when there is no load. Specifically, as shown in FIG. 3A, a map that defines the correlation between the accelerator pedal operation amount (deg), which is accelerator opening information, and the engine speed (rpm) at no load is stored. Has been. In the map shown in FIG. 3 (a), the accelerator pedal operation amount and the engine speed X at no load are substantially proportional, and the engine speed X at no load increases as the accelerator pedal operation amount increases. It is prescribed to be. The engine speed X when the accelerator pedal operation amount is zero is set to the engine speed at idling.

  The engine speed estimation means 42 shown in FIG. 2 estimates the engine speed X when there is no load corresponding to the actual accelerator opening. In this embodiment, the engine speed estimation means 42 is acquired by the accelerator opening acquisition means 20. By searching the engine speed storage means 41 using the accelerator opening information as a search key, the engine speed X at no load corresponding to the actual accelerator opening is estimated. That is, the engine speed estimation means 42 obtains the accelerator pedal operation amount as the accelerator opening information from the accelerator opening acquisition means 20 and the engine speed X that matches the acquired accelerator pedal operation amount. A function of searching from a map stored in the number storage means 41 and a function of outputting the searched engine speed X at no load to the deviation calculating means 43 are provided.

  The deviation calculating means 43 calculates the deviation ΔZ by subtracting the actual engine speed Y from the engine speed X estimated by the engine speed estimating means 42. That is, the deviation calculating means 43 has a function of acquiring the engine speed X at no load corresponding to the actual accelerator opening from the engine speed estimating means 42 and the actual engine speed Y of the engine speed acquiring means 20. , A function for calculating the deviation ΔZ (= XY), and a function for outputting the calculated deviation ΔZ to the determination means 46.

The cancellation reference value storage means 44 stores a correlation between accelerator opening information correlated with the accelerator opening and a cancellation reference value. In the present embodiment, as shown in FIG. 3B, a map that defines the correlation between the accelerator pedal operation amount (deg) that is accelerator opening information and the release reference value ΔZ ₀ (rpm) is stored. Yes. In the map shown in FIG. 3 (b), is defined as removing reference value [Delta] Z ₀ as the accelerator pedal operation amount is large is increased.

The release reference value search means 45 searches the release reference value storage means 44 for the release reference value ΔZ ₀ corresponding to the accelerator opening information acquired by the accelerator opening acquisition means 20. That is, the release reference value search means 45 has a function of acquiring the accelerator pedal operation amount as the accelerator opening information from the accelerator opening acquisition means 20 and the release reference value ΔZ ₀ that matches the acquired accelerator pedal operation amount. A function of searching from a map stored in the value storage means 44 and a function of outputting the searched release reference value ΔZ ₀ to the determination means 46 are provided.

Judging means 46, in which deviations [Delta] Z calculated by the deviation calculation means 43 determines whether a release reference value [Delta] Z ₀ or higher. That is, the determination means 46, the release function of acquiring the deviations [Delta] Z calculated by the deviation calculation means 43, a function of acquiring a release reference value [Delta] Z ₀ searched in removing reference value search unit 45, the acquired deviation [Delta] Z A function of comparing the reference value ΔZ ₀ and a function of outputting the comparison result to the holding control means 47 are provided.

The holding control means 47 controls the cut valve 1 as a braking force holding means. Specifically, the holding control means 47 closes the cut valve 1 when a predetermined start condition (for example, the brake fluid pressure detected by the pressure sensor 8 is equal to or higher than a predetermined value and the vehicle body speed is zero) is satisfied. holding control (i.e., control for energizing the electromagnetic coil (not shown)) to the valve starts, the deviation [Delta] Z in the determination means 46 ends the holding control when it is determined that the release reference value [Delta] Z ₀ or higher. The vehicle body speed is calculated based on the rotational speed (wheel speed) detected by the wheel speed sensor S attached to each of the four wheels.

  Although not shown, the control unit 40 includes an anti-lock brake control unit that executes anti-lock brake control, a behavior stabilization control unit that executes behavior stabilization control such as skid control and traction control, and the like. Yes.

  Referring to FIG. 1, the anti-lock brake control means determines whether or not the wheel is likely to fall into a locked state (that is, whether or not the slip ratio is larger than a predetermined value), and enters the locked state. When it is determined that the valve 9 is likely to fall, the corresponding control valve means V performs control for closing the inlet valve 2 and opening the outlet valve 3, and in this state, the motor 9 is driven to drive the pump 6. The control which operates is performed. If it does in this way, the brake fluid which was acting on the wheel brake of the wheel which was going to be in a locked state will be decompressed, and the slip of a wheel will be eased.

  For example, when it is determined that the wheel should be braked when the brake pedal L is not operated, the behavior stabilization control means closes the cut valve 1 and opens the intake valve 4. Then, the control valve means V other than the control valve means V corresponding to the wheel to be braked is controlled to close the inlet valve 2, and in this state, the motor 9 is operated to drive the pump 6. In this way, the brake fluid stored in the master cylinder M, the output hydraulic pressure path A, and the suction hydraulic pressure path C passes through the pump 6 and the discharge hydraulic pressure path D to the wheel cylinder W of the wheel to be braked. As a result, the brake fluid pressure is applied to the wheel cylinder W.

  The vehicular brake control device U configured as described above is set so that a control program corresponding to the flowchart shown in FIG. 4 is started when the ignition is turned on. In addition, illustration of the flowchart corresponding to anti-lock brake control and behavior stabilization control is abbreviate | omitted.

  When the control program described above is activated, step 100 is first executed. In step 100, the holding control means 47 determines whether or not a holding control start condition (for example, the brake fluid pressure detected by the pressure sensor 8 is equal to or higher than a predetermined value and the vehicle body speed is zero) is satisfied. The

  If it is determined in step 100 that the holding control start condition is satisfied, the process proceeds to step 110, and control for holding the braking force is executed. That is, control for closing the cut valve 1 is executed. When the cut valve 1 is closed, the braking force (brake hydraulic pressure) applied to the wheel brake of the stopped vehicle is maintained. If it is determined that the holding control start condition is not satisfied, the process proceeds to “RETURN”.

Next, the routine proceeds to step 120, where the engine speed X is estimated by the engine speed estimation means 42 based on the accelerator opening information acquired by the accelerator opening acquisition means 20, and the release reference value The search means 45 searches for the release reference value ΔZ ₀ .

  Subsequently, the routine proceeds to step 130 where the deviation calculating means 43 calculates a deviation ΔZ between the engine speed X at no load and the actual engine speed Y acquired by the engine speed acquiring means 30. The actual engine speed Y used when calculating the deviation ΔZ is acquired at the same time as the accelerator opening information used when estimating the engine speed X when there is no load. It is desirable that

Then, in step 140, whether the deviation [Delta] Z in the judgment unit 46 is released the reference value [Delta] Z ₀ or higher is determined. When it is determined that the deviation ΔZ is less than the release reference value ΔZ ₀ (No), the process proceeds to “RETURN”.

If it is determined in step 140 that the deviation ΔZ is greater than or equal to the release reference value ΔZ ₀ (Yes), the process proceeds to step 150 where the braking force is released. That is, the control for closing the cut valve 1 is terminated.

  The operation of the vehicle brake control device U will be described more specifically with reference to FIG. Here, (a) in FIG. 5 is a time chart showing the presence or absence of holding control (that is, the open / closed state of the cut valve 1), (b) is a time chart showing the transition of the vehicle body speed, and (c) is the transition of the braking force. (D) is a time chart showing the transition of the accelerator pedal operation amount correlated with the accelerator opening, (e) is a time chart showing the estimated engine speed and the transition of the actual engine speed, ( f) is a time chart showing the transition of the deviation between the estimated engine speed and the actual engine speed. FIG. 5 is a time chart assuming a manual transmission vehicle, but is not intended to limit the application range of the vehicle brake control device U.

When the driver depresses the brake pedal while the vehicle is traveling uphill, braking force (brake hydraulic pressure in the present embodiment) is applied to the wheel brake. When the vehicle is decelerated by this braking force and the vehicle body speed becomes zero with the braking force applied (time t _{1 in} FIG. 5 (b)), the holding control start condition is satisfied. Control is started (see FIG. 5A), and the cut valve 1 (see FIG. 1), which is a braking force holding means, is closed. That is, the braking force is maintained by the action of the cut valve 1 (see FIG. 1) regardless of whether or not the brake pedal is depressed (see (c) of FIG. 5). In other words, even if the driver releases the brake pedal, the vehicle will not “backward”.

While stopped in the idling state (time t _{1 to} t ₂ ), the engine speed X estimated from the accelerator pedal operation amount and the actual engine speed Y substantially coincide (see FIG. 5E). Since these deviations ΔZ are less than the release reference value ΔZ ₀ (see (f) of FIG. 5), the holding control is continued (see (a) of FIG. 5).

From the time the driver depresses the accelerator pedal to start the vehicle until the clutch is operated and the clutch is in the half clutch state (time t _{2 to} t ₃ ), the engine speed X estimated from the accelerator pedal operation amount actual engine speed Y and is almost identical (see (e) in FIG. 5), since these deviations ΔZ is the release reference value ΔZ below ₀ (see (f) in FIG. 5), the holding control is continued As a result, “backward movement” of the vehicle is prevented.

When the half-clutch state or the clutch is completely connected, the engine speed X estimated from the accelerator pedal operation amount deviates from the actual engine speed Y (see FIG. 5E), but these deviations ΔZ As long as is less than the release reference value ΔZ ₀ (see (f) of FIG. 5), the holding control is continued (see (a) of FIG. 5).

When the deviation ΔZ between the engine speed X estimated from the accelerator pedal operation amount and the actual engine speed Y reaches the release reference value ΔZ ₀ (time t _{4 in} FIG. 5 (f)), the holding control is released (FIG. 5). As a result, the braking force is released (see (c) of FIG. 5). In the present embodiment, the vehicle starts before the holding control is released ((b) time t _{3 to} t _{4 in} FIG. 5), but the timing at which the vehicle starts is determined by the braking force or the release reference value ΔZ. It varies according to the size of ₀ , vehicle weight, road surface condition, and the like.

According to the brake control apparatus for a vehicle described above, or to hold the braking force with whether the deviation [Delta] Z between the actual engine speed Y and the engine rotational speed X at no load is released the reference value [Delta] Z ₀ or higher If it is determined whether or not the engine speed Y changes irregularly due to factors other than the accelerator operation, such as when the rate of change of the actual engine speed Y remains small, such as when the half-clutch state continues for a long time. Even in such a case, the timing for releasing the braking force is not misunderstood, and therefore the driver's feeling of operation can be kept good while preventing the vehicle from being “backwardly moved”.

  Further, in this embodiment, since the relationship between the accelerator pedal operation amount correlated with the accelerator opening and the engine speed X at no load is defined in advance (see FIG. 3A), the accelerator opening. It is possible to easily and reliably estimate the engine speed X at no load corresponding to.

Further, in the present embodiment, the release reference value ΔZ ₀ is changed according to the accelerator pedal operation amount correlated with the accelerator opening, so that the braking force applied to the wheel brake is released at a more appropriate timing. It becomes possible. That is, as the slope of the uphill increases, the need to maintain braking force at the time of starting increases. However, as the slope of the uphill increases, the amount of accelerator pedal operation tends to increase. as the amount increases, if the like is released the reference value [Delta] Z ₀ becomes larger set, become promptly hold control is canceled by a gradual ascent less need to hold the braking force when moving off On a steep uphill with a high necessity for holding braking force, the holding control continues for a sufficient period until the vehicle moves forward. Further, if the release reference value ΔZ ₀ is set to increase as the accelerator pedal operation amount increases, sudden start can be suppressed on flat ground, downhill, and the like.

The configuration of the vehicle brake control device U described above may be changed as appropriate. For example, in the present embodiment, the map shown in FIG. 3A is stored in the engine speed storage means 41. Instead, for example, the accelerator opening degree and the engine speed X at no load are stored. It is also possible to store a function that defines the correlation between the two. Similarly, a function that defines the correlation between the accelerator opening and the release reference value ΔZ ₀ may be stored in the release reference value storage unit 44.

  In the present embodiment, the hydraulic circuit capable of anti-lock brake control and behavior stabilization control is exemplified as the hydraulic circuit capable of holding control. However, the hydraulic circuit capable of holding control is limited. Not the purpose. For example, even in a hydraulic circuit that cannot perform anti-lock brake control or behavior stabilization control, a normally open solenoid valve that serves as a braking force holding means is provided in the flow path from the master cylinder to the wheel cylinder of the wheel brake. By providing, the above-described holding control can be executed.

  Moreover, in this embodiment, although the case where a wheel brake was a hydraulic type was illustrated, it may be an electric type.

1 is a hydraulic circuit diagram of a vehicle brake control device according to an embodiment of the present invention. 1 is a block configuration diagram of a vehicle brake control device according to an embodiment of the present invention. (A) is a map that defines the correlation between the accelerator pedal operation amount and the engine speed when there is no load, and (b) is a map that defines the correlation between the accelerator pedal operation amount and the release reference value. It is a flowchart for demonstrating operation | movement of the brake control apparatus for vehicles which concerns on embodiment of this invention. (A) is a time chart showing the presence or absence of holding control, (b) is a time chart showing the transition of the vehicle body speed, (c) is a time chart showing the transition of the braking force, and (d) is a transition of the accelerator opening. (E) is a time chart showing the transition of the estimated engine speed and the actual engine speed, and (f) is a time chart showing the transition of the deviation between the estimated engine speed and the actual engine speed. It is.

Explanation of symbols

U Brake control device for vehicle 1 Braking force holding means (cut valve)
20 Accelerator opening degree acquisition means 30 Engine rotation speed acquisition means 41 Engine rotation speed storage means 42 Engine rotation speed estimation means 43 Deviation calculation means 44 Release reference value storage means 45 Release reference value search means 46 Determination means 47 Holding control means

Claims (2)

Braking force holding means for holding braking force applied to the wheel brake of the stopped vehicle;
Engine speed estimation means for estimating the engine speed at no load corresponding to the actual accelerator opening;
Deviation calculating means for calculating a deviation by subtracting the actual engine speed in a state where the load from the clutch is acting on the engine from the engine speed at no load estimated by the engine speed estimating means;
An accelerator opening obtaining means for obtaining an accelerator pedal operation amount correlated with the accelerator opening;
A release reference value storage means for storing a correlation such that the release reference value increases as the value of the accelerator pedal operation amount correlated with the accelerator opening increases;
A release reference value search means for searching for a release reference value corresponding to the accelerator pedal operation amount acquired by the accelerator opening acquisition means from the release reference value storage means;
A vehicle brake control device comprising: determination means for determining whether or not the deviation calculated by the deviation calculation means is equal to or greater than a release reference value searched by the release reference value search means;
The vehicle brake control device according to claim 1, wherein the braking force holding unit releases the braking force when the determination unit determines that the deviation is equal to or greater than the release reference value. An engine speed storage means for storing a correlation between an accelerator pedal operation amount correlated with the accelerator opening and an engine speed at no load;
The engine speed estimation means searches the engine speed storage means using the accelerator pedal operation amount acquired by the accelerator opening acquisition means as a search key, so that no load corresponding to the actual accelerator opening can be obtained. The vehicle brake control device according to claim 1, wherein the engine speed is estimated.

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