JP2008080847A - Braking force control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force control device capable of producing a sticky feeling in brake changes when brake returning operation is carried out from a high G area of braking, in a brake-by-wire system. <P>SOLUTION: In the braking force control device, a contribution degree of master cylinder pressure P and depressing stroke amount S when a target deceleration G is set to increase the contribution degree of the master cylinder pressure P in proportion to the master cylinder pressure P. A braking force controlling means limits the lowering of the target deceleration G in a stroke delay area L where returning delay of a brake pedal occurs, when it is determined that the returning operation of the brake pedal 1 is carried out while the contribution degree of the master cylinder pressure P is larger than the contribution degree of the depressing stroke amount S. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking force control device capable of controlling the working fluid pressure to the wheel cylinder of each wheel by brake-by-wire, separately from the working fluid pressure from a master cylinder.

As a conventional braking force control device, for example, there is a device described in Patent Document 1. In this device, each wheel cylinder is connected to the master cylinder via an electromagnetic on-off valve, and braking is possible by the master cylinder pressure.
Also, during normal braking, during brake-by-wire control (hereinafter simply referred to as BBW control), the electromagnetic on-off valve is closed and communication between the master cylinder and the wheel cylinder is shut off, and the pump is operated as a drive source. The braking force by the wheel cylinder of each wheel is controlled.

  The target deceleration G of the BBW control by the pump is calculated based on both the brake pedal depression stroke amount and the master cylinder pressure. That is, the first temporary target deceleration Gp is calculated based on the master cylinder pressure, and the second temporary target deceleration Gs is calculated based on the stepping stroke amount. The following formulas are used for the two temporary target decelerations Gp and Gs. As described above, the final target deceleration G is calculated by weighting with the basic contribution α.

G = α · Gp + (1-α) Gs
The basic contribution α is set so that the contribution degree of the master cylinder pressure increases as the previous target deceleration (substantially synonymous with the master cylinder pressure) increases, and the master cylinder exceeds a predetermined level when the brake pedal is depressed. In the state where the pressure is reached, the master cylinder pressure is emphasized, and for example, the contribution degree of the master cylinder pressure is 100%.

Such a contribution degree is set for the following reason. That is, since there is a delay in the generation of the master cylinder pressure at the start of the depression of the brake pedal, the contribution degree of the depression stroke amount is set to be large (contribution α is small) when the depression stroke amount is small. In addition, in relation to the depression force and stroke amount of the brake pedal, the greater the depression stroke amount, the smaller the increase in stroke amount with respect to the increase in depression force. Therefore, when the depression stroke amount is large, the contribution degree of the master cylinder pressure is increased ( The contribution degree α is set large). As a result, the depression force of the brake pedal operated by the driver can be accurately reflected in braking.
JP 11-301434 A

In general, due to the hysteresis of the master cylinder and brake pedal, the relationship between the master cylinder pressure and the pedal stroke is different between when the brake pedal is depressed and when it is returned. The rate of decrease in cylinder pressure tends to increase.
Further, in the above prior art, since the degree of contribution of the master cylinder pressure is fixed to 1 (= 100%) above a certain braking G, it is reduced when it is assumed that the brake pedal starts to be returned from the high G region of the braking. The decreasing speed of the master cylinder pressure with a high speed is reflected in the target deceleration as it is, and the decreasing speed of the target deceleration is increased together with the decreasing speed of the master cylinder pressure. As a result, there is a problem that it is not possible to give a sticky feeling to the braking change during the brake return operation.
The present invention has been made paying attention to the above points, and provides a braking force control device capable of producing a feeling of sticking to a braking change in a brake-by-wire operation when a brake is returned from a high G region of braking. Is an issue.

In order to solve the above-described problems, the present invention provides a master cylinder that outputs a master cylinder pressure corresponding to a driver's brake pedal depression stroke, and at least the master cylinder pressure and the brake pedal depression stroke amount at the master cylinder pressure. Braking control means for controlling the braking force of the wheel cylinder so that the target deceleration is calculated based on the target deceleration, and the master cylinder pressure and the depression stroke amount when calculating the target deceleration are included. In the braking force control device in which the contribution degree is set to be larger as the master cylinder pressure is larger,
When the braking control means determines that the return operation of the brake pedal has been performed in a state where the contribution degree of the master cylinder pressure is greater than the contribution degree of the stepping stroke amount, a stroke delay in which a return delay of the brake pedal has occurred. The region is characterized in that the reduction of the target deceleration is limited.

  According to the present invention, even during brake-by-wire control, when the brake pedal is returned from the high G range, a sudden decrease in the target deceleration can be prevented and the master cylinder is connected to the wheel cylinder. It is possible to give a feeling of stickiness to a change in braking in a state close to braking at.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a braking force control apparatus according to the present embodiment.
(Constitution)
In FIG. 1, reference numeral 1 denotes a brake pedal 1 that constitutes a braking operator that is braked by a driver. The brake pedal 1 is connected to a hydraulic pressure booster and a master cylinder 2. The master cylinder 2 is connected to the respective wheel cylinders 3FR to 3RR through the first communication path 5-1 or the second communication path 5-2. In FIG. 1, reference numeral 4 denotes a reservoir.

In the present embodiment, the first communication passage 5-1 is connected to the wheel cylinder 3FR for the right front wheel and the wheel cylinder 3RR for the left rear wheel through the first electromagnetic shut-off valve 6-1. The second communication passage 5-2 is connected to the wheel cylinder 3FL for the left front wheel and the wheel cylinder 3RL for the right rear wheel through the second electromagnetic cutoff valve 6-2.
Here, the electromagnetic shut-off valves 6-1 and 6-2 are in an open state when not energized, and the hydraulic pressure of the master cylinder 2 can be supplied to the wheel cylinders 3FR to 3RR. The electromagnetic shut-off valves 6-1 and 6-2 constitute switching means.

  In the present embodiment, the braking on the right front wheel side and the left rear wheel side communicating with the first communication path 5-1 constitutes the first braking system, and the left front wheel side communicating with the second communication path 5-2 and the right Rear wheel braking constitutes a second braking system, and BBW control is possible by individual pumps 8-1 and 8-2 as will be described later. Of course, the first brake system and the second brake system may be driven by the same pump.

The circuit configurations on the first braking system side and the second braking system side will be described. Since the circuit configuration of the first braking system and the circuit configuration of the second braking system are the same configuration, the configuration will be mainly described for the first braking system.
Reference numerals 7-1, 7-2 and 8-1, 8-2 denote braking force actuators (drive sources different from the master cylinder 4) for generating a braking force in the BBW control. 2 and hydraulic pumps 8-1 and 8-2 driven by the motors 7-1 and 7-2. The operations of the motors 7-1 and 7-2 are controlled by control signals (control currents) from the actuator controllers 9-1 and 9-2, and the hydraulic pump 8- 1 and 8-2 are driven. In FIG. 1, gear pumps are illustrated as the hydraulic pumps 8-1 and 8-2. The hydraulic pumps 8-1 and 8-2 have input ports connected to the reservoir 4 via second pipes 10-1 and 10-2, and discharge ports described above via third pipes 11-1 and 11-2. By being connected to the first communication path 5-1, the working fluid in the reservoir 4 is sucked through the second pipes 10-1 and 10-2, and the working fluid is drawn into the third pipe 11-1, It is possible to discharge to the wheel cylinders 3FR to 3RR via 11-2. In the middle of the third pipes 11-1 and 11-2, holding valves 12-1 and 12-2 made of electromagnetic proportional valves are inserted. The wheel cylinders 3FR to 3RR are connected to the second pipes 10-1 and 10-2 communicating with the reservoir 4 through the fourth pipes 13-1 and 13-2, and the fourth pipes 13-1 and 13-2 are connected. Connected to 13-2 are pressure reducing valves 14-1 and 14-2 comprising electromagnetic proportional valves. Reference numerals 15-1 and 15-2 denote relief valves, and reference numerals 16-1 and 16-2 denote check valves.

Here, each said valve is controlled by the command from corresponding actuator controller 9-1, 9-2.
In the BBW control state, the shutoff valves 6-1 and 6-2 are closed, and when the pressure is increased, the holding valves 12-1 and 12-2 are opened, and the pressure reducing valves 14-1 and 14- 2 is closed, and the working fluid discharged from the pumps 8-1 and 8-2 is supplied to the wheel cylinders 3 FR to 3 RR to increase the pressure, and when the pressure is reduced, the holding valves 12-1 and 12-2 are closed. In this state, the pressure reducing valves 14-1 and 14-2 are opened, and the working fluid in the wheel cylinders 3FR to 3RR is returned to the reservoir 4 and depressurized. Note that the holding valves 12-1 and 12-2 are appropriately closed when the hydraulic pressure is held by slip control, front / rear braking force distribution control, or the like.

  Further, in FIG. 1, reference numeral 20 denotes a stroke simulator. The stroke simulator 20 is connected to the master cylinder 2 via an electromagnetic opening / closing valve 21. The electromagnetic on-off valve 21 is in a closed state when not energized, and is controlled in an open state in synchronization with the shutoff valves 6-1 and 6-2 being switched to a closed state by a command from the brake controller 22. As a result, the stroke simulator 20 operates. That is, during the BBW control, the master cylinder pressure P is absorbed by the stroke simulator 20 to realize a natural pedal effort.

The actuator controllers 9-1 and 9-2 are provided for each of the two braking systems, and the actuator controllers 9-1 and 9-2 correspond to the actuators of the corresponding braking system in response to a command from the brake controller 22. Control the state of
Here, reference numeral 24 denotes a stroke sensor, which detects the operation amount of the brake pedal 1 and outputs it to the brake controller 22. Reference numerals 23-1 and 23-2 are pressure sensors that are provided for each braking system and detect a master cylinder pressure P (corresponding to a driver's required braking amount), and send the detected pressure signal to the brake controller 22. Output. The pressure signals detected by the two pressure sensors 23-1, 23-2 are substantially the same except in special cases. Reference numerals 25FR to 25RR are pressure sensors that detect the wheel cylinder pressure Pwc of each of the wheel cylinders 3FR to 3RR, and output the detected pressure signal to the brake controller 22. Reference numerals 26-1 and 26-2 are pressure sensors that detect the discharge pressures of the pumps 8-1 and 8-2, and output the detected pressure signals to the brake controller 22.

  The brake controller 22 is constituted by, for example, a CPU, ROM, RAM, digital port, A / D port, and a one-chip microcomputer incorporating various timer functions (or a plurality of chips realizing the same function). The brake controller 22 outputs control signals to the valves and the motors 7-1 and 7-2 via the actuator controllers 9-1 and 9-2.

During normal control, the brake controller 22 closes the electromagnetic shut-off valves 6-1 and 6-2 as the second braking control state so that the BBW control state is established, and opens the electromagnetic on-off valve 21 for the stroke simulator 20. The stroke simulator 20 is operated as a state to enable a natural pedal effort.
Further, when a failure is detected such that the hydraulic pressure cannot be generated by the pumps 8-1 and 8-2, the first electromagnetic cutoff valve 6-1 and the second electromagnetic cutoff valve 6-2 are set as the first braking control state. Is opened, and the electromagnetic on-off valve 21 for the stroke simulator 20 is returned to the closed state, and the hydraulic pressure of the master cylinder 2 is supplied to each wheel cylinder via the first communication path 5-1 and the second communication path 5-2. Introduced into 3FR-3RR.

Next, the control (BBW control) in the second braking control state in the brake controller 22 will be described with reference to FIG. This process constitutes a braking control means.
If an abnormality that does not appear in the following process but may cause the braking control system to not function normally is detected, the power supply to each valve and the motors 7-1 and 7-2 is cut off. That is, the first electromagnetic cutoff valves 6-1 and 6-2 and the second electromagnetic cutoff valves 6-1 and 6-2 are both opened, and the on-off valve 21 for the stroke simulator 20 is returned to the closed state. Then, the hydraulic pressure of the master cylinder 2 is introduced into each of the wheel cylinders 3FR to 3RR through the first communication path 5-1 and the second communication path 5-2, and the first braking control state is set.

As shown in FIG. 2, it operates at a predetermined sampling cycle. First, in step S10, the current master cylinder pressure P is used, and based on the map as shown in FIG. The basic contribution α taking a value is obtained and the process proceeds to step S20.
That is, in a region where the depression stroke amount S is small and the master cylinder pressure P is small at the depression start timing of the brake pedal 1, the basic contribution degree α is made small to emphasize the depression stroke amount, and the depression stroke amount is large and a predetermined master cylinder is set. Above the pressure P, the basic contribution α is increased with an emphasis on the master cylinder pressure P. When the master cylinder pressure P0 exceeds the predetermined value, the basic contribution α is set to 1 (= 100%) in the high G region. Yes. This basic contribution α is a value from 0 to 1, and indicates the contribution degree on the master cylinder pressure P side, and the contribution degree on the stepping stroke side is (1−α).

  In step S20, it is determined whether or not the current basic contribution α is 1 or more. On the other hand, when the basic contribution α is less than 1, the process proceeds to step S90, and after the value of the basic contribution α is substituted for the master pressure contribution k, the process proceeds to step S100. That is, when the basic contribution α is less than 1 which is not the high G region, the master pressure contribution k is the same value as the basic contribution α.

In step S30, it is determined whether or not the brake pedal returning operation is being performed. If it is determined that the brake pedal returning operation is being performed, the process proceeds to step S40. If it is determined that the brake return operation is not being performed, the process proceeds to step S70. In step S70, the current master contribution k is held, that is, the previous value is maintained and the process proceeds to step S100.
Whether the brake pedal return operation is being performed is determined, for example, based on whether or not the change ΔP in the master cylinder pressure P has decreased below a predetermined value. At this time, it may be determined whether or not the change amount ΔS of the stepping stroke amount S is 0 or less, or whether the current master cylinder pressure P is a predetermined value or more.
In step S40, it is determined whether or not it is the stroke delay region L. If it is determined that the stroke is the stroke delay region L, the process proceeds to step S50, and if it is not the stroke delay region L, the process proceeds to step S60.

Whether or not the stroke is in the stroke delay region L is determined to be in the stroke delay region L when, for example, the pedal stroke reduction rate is small with respect to the reduction rate of the master cylinder pressure P. That is, from the state where the brake pedal 1 is depressed and the master cylinder pressure P is in a high pressure state, in order to reduce the braking, the driver has started the brake return operation by reducing the pedaling force applied to the brake pedal. In this case, although the decrease rate of the master cylinder pressure P is fast as a change corresponding to the decrease in the pedaling force, the brake pedal does not return immediately even if the pedaling force becomes weak because the master cylinder 2 is in a high pressure state. Start returning with. The region until the start of the return is the stroke delay region L. In this stroke delay region L, the pedal stroke decreasing speed is extremely slow so that the brake pedal hardly moves or slightly moves.
That is, the stroke delay region L is a region in the return speed state that is significantly smaller than the return speed of the brake pedal assumed by the master cylinder pressure reduction rate.

In step S50, the contribution degree k ′ that can hold the previous target deceleration is calculated, and the process proceeds to step S80. For example, as shown in the following equation, a difference ΔP between the previous master cylinder pressure P (n−1) and the current master cylinder pressure P is multiplied by a predetermined gain β to calculate an increase Δk, and that amount is calculated as a master. The calculation contribution k ′ is obtained by adding to the calculation contribution k.
The calculation contribution k ′ indicates the final value of the target deceleration reduction limit during the stroke delay process.
k ′ = k + ΔP × β
In step S80, the calculation contribution degree k 'is substituted for the master contribution degree k as in the following equation, and the process proceeds to step S100.
k = k ′

When it is determined that the brake pedal 1 is being returned, and the process proceeds to step S60, the master contribution k is calculated based on the following equation.
k = {(k′−k0) / (P′−P0) × (P−P0)} + k0 (1)
here,
k ′ is the degree of contribution when the stroke delay region L ends,
P ′ is a contribution degree when the stroke delay region L ends,
P0 is the lowest master cylinder pressure P at which the basic contribution α is 1.
k0 is the basic contribution at the time of P0, and can be replaced with the basic contribution α in the present embodiment.

P represents the current master cylinder pressure P. When the process proceeds to step S60, the basic contribution α is 1.
By adopting this equation (1), the master contribution k that has been increased due to the restriction on the reduction in the target deceleration during the stroke delay process gradually decreases, and further, the master contribution immediately before α becomes less than 1. The restriction on the decrease in the target deceleration can be gradually relaxed so that the degree k coincides with α.

In step S100, the target deceleration G is calculated based on the current master cylinder pressure P and the depression stroke amount S of the brake pedal 1, and the wheel cylinder pressure Pwc of each wheel that becomes the target deceleration G is calculated. The control command value that becomes the pressure Pwc is output to the actuator controllers 9-1 and 9-2, and is returned. For example, the control currents of the motors 7-1 and 7-2 are controlled based on the difference between the calculated target deceleration G and the current deceleration.
Here, calculation of the target deceleration G of the present embodiment will be described.
The temporary target deceleration Gp due to the master cylinder pressure P is calculated based on, for example, FIG. Since the master cylinder pressure P has a substantially linear relationship with the pedaling force, the master cylinder pressure P is set to be a map as shown in FIG.

Further, the temporary target deceleration Gs is obtained from the stroke amount S based on a map as shown in FIG. The stroke amount S is set to a value along the map as shown in FIG. 5 in view of the fact that the greater the increase in the pedaling force with respect to the stroke change, the greater the stroke amount S.
Then, the final target deceleration G is calculated from the temporary target decelerations Gp and Gs of both the stroke amount S and the master cylinder pressure P based on the following equation.
G = (1-α) × Gs + k × Gp (2)

(Function and effect)
In the brake control device having the above-described configuration, when the brake pedal 1 is depressed, the target deceleration G is obtained with an emphasis on the depression stroke amount S in the initial depression, and the master cylinder pressure P is greater than a predetermined master cylinder pressure P. By changing the degree of contribution so as to be important, it is possible to accurately reflect the driver's braking force on the deceleration. Note that the pedal feeling is secured by the stroke simulator in a state close to the state in which the master cylinder and the wheel cylinder communicate with each other.

  On the other hand, when the driver performs a pedal return operation while the brake pedal 1 is depressed until the basic contribution α of the master cylinder pressure P reaches a high G region of 1 or more, When the target deceleration G is calculated with the contribution degree of the master cylinder pressure P being 100%, the target deceleration G is greatly reduced. On the other hand, in the present embodiment, in the stroke delay region L with respect to the decrease in the pedaling force, the contribution degree of the master cylinder pressure P is set to the basic contribution degree α (= 1) so as to limit the decrease in the target deceleration G. Therefore, a large decrease speed of the master cylinder pressure P is not reflected in the target deceleration G as it is, and a sudden decrease in the target deceleration G can be prevented and a sticky feeling can be given. Can do.

The above will be described with reference to FIG. 6 which is a schematic diagram. FIG. 6A shows a comparative example, and FIG. 6B shows the case of the present embodiment to which the present invention is applied.
When the pedal force applied to the pedal that has been depressed as the pedal return operation decreases, the temporary target deceleration Gp based on the master cylinder pressure P decreases accordingly.
At this time, the setting of the relationship between the master cylinder pressure P and the temporary target deceleration Gp as shown in FIG. 4 is set by the behavior when the brake pedal 1 is depressed. Since the change speed of the master cylinder pressure P is larger when the master cylinder pressure P is returned than when it is depressed, the provisional target deceleration Gp is also greater than the decrease speed when the master cylinder pressure P is depressed. Further, when the pedal force applied to the brake pedal 1 is weakened with the high G and the master cylinder pressure P being high, the depression stroke amount S of the brake pedal 1 does not decrease immediately by an amount corresponding to the decrease in the pedal force. It decreases after a predetermined stroke delay has occurred.

  For this reason, as in the comparative example, when the temporary target deceleration Gp is calculated by setting k = α to be the final target deceleration G, the target deceleration G tends to decrease. On the other hand, in the present embodiment, as shown in FIG. 6B, by correcting the contribution degree largely, in a state where the stroke is delayed, the decrease in the target deceleration G is limited, and the brake pedal It is possible to give a sticky feeling corresponding to the return state of 1. Since FIG. 6 is a schematic diagram, the reduction of the target deceleration G is illustrated as zero, but the object of the present invention is achieved if the decrease gradient is small. Similarly, the temporary target deceleration Gs in the stroke delay region L is also described as being constant, but is reduced at a small reduction rate.

Here, the degree of stickiness can be adjusted by adjusting the gain β.
Further, the reason why the master contribution k is gradually decreased in step S60 is as follows.
Since the amount of stroke change with respect to the change in pedaling force varies depending on the amount of brake depression, the amount of pedaling can be reflected in deceleration more accurately by focusing on the amount of stroke in the initial stage of brake depression and emphasizing the master cylinder pressure P in the later stage of brake depression. Therefore, in the deceleration region where the basic contribution α of the master cylinder pressure P is less than 1 (master cylinder pressure P region), it is possible to reflect the pedaling force more accurately by increasing the contribution of the stepping stroke amount S.

  For this reason, when the brake pedal 1 is returned in the state in which the basic contribution α is 1 by the process of step S60, the basic contribution α of the master cylinder pressure P is set to be larger than 1 until it starts to become less than 1. The contribution degree of the increase in the master contribution degree k is decreased toward 1. By doing so, it is possible to give a feeling of stickiness in the region where the basic contribution α of the master cylinder pressure P is 1 as described above, and before the basic contribution α becomes less than 1, the contribution for the master By changing k so that it becomes 1, it is possible to prevent the change in the master contribution k from being stepped, and in a region where the contribution is less than 1, the target braking force according to the driver's pedaling force is accurately determined. It can be reflected well.

In the case of the high G region where the basic contribution α is 1, if the brake is held or the brake is depressed again during the brake return operation, the limit amount for limiting the target deceleration G is held. That is, the master contribution k is held at the previous value for the following reason.
As described above, when the reduction of the target deceleration G is limited so that the master contribution k is greater than 1 and the limit is gradually decreased, the brake pedal 1 is returned from the middle of the return operation. In this case, if the master contribution k is continuously decreased toward 1, the increase rate of the target deceleration G may be decreased although the pedal effort is increased. On the other hand, in this embodiment, when the pedal is depressed again or the pedal is held, the reduction of the limit amount of the target deceleration G is limited and stopped. That is, by maintaining the master contribution k, the target deceleration G can be increased according to the increase in the master cylinder pressure P, and the driver's request can be reflected in the target deceleration G.

  FIG. 7 shows an example of a time chart when this embodiment is adopted. This example of a term chart exemplifies the case where braking with a basic contribution α of 1 is in the high G region, the return operation is performed, and the brake return is once held in the middle, and there are two stroke delay regions L The case of doing is illustrated. As can be seen from this time chart, during the brake return operation, a sudden decrease in the target deceleration G is suppressed, and the target deceleration G is reduced by a change close to the change in the depression stroke amount S of the brake pedal 1. I understand that.

  Here, the brake pedal 1 is returned by the above processing. When the basic contribution degree α before the loss stroke region or the stepping stroke amount S that is the braking release position becomes zero is less than 1, the limit amount (difference between k and α) due to the above reduction restriction is zero. Once the brake pedal 1 is returned and the basic contribution α once becomes less than 1, there is no limit amount.

  Here, in the above embodiment, the reduction of the target deceleration G is limited by making the contribution degree of the temporary target deceleration G based on the master cylinder pressure P larger than 1, but the reduction limit is limited to this. Not. For example, a master cylinder pressure Ps for calculating the temporary target deceleration G is separately set for the detected master cylinder pressure P, and when the reduction is limited, a predetermined correction amount (for example, for the detected master cylinder pressure P (for example, The reduction limitation may be performed by adding the amount corresponding to the decrease in the master cylinder pressure P) to obtain the calculation master cylinder pressure Ps.

In the present embodiment, the limit amount (difference between k and α) due to the lower limit is set so as to disappear when the master cylinder pressure P0 is reached (k = α), but is not limited thereto.
When the master contribution k obtained by the above-described equation (1) is less than the predetermined gradient and less than the predetermined gradient k, the gradient is larger than the gradient before the master cylinder pressure P0 reaches k. May be set to be equal to each other, that is, the limit amount is eliminated.

In the above embodiment, the target deceleration G is set to be limited only when the basic contribution α is 1. However, the present invention is not limited to this. For example, a region where the basic contribution α exceeds 0.5 may be set as a target region for reduction restriction. Moreover, since the map of FIG. 3 is an example, it may be another map. The present invention is applicable if the basic contribution α is set to increase as the master cylinder pressure P increases.
Here, although the case where there are two braking systems is illustrated in the above embodiment, the number may be one, or the wheel cylinders may be divided into three or more and the braking systems may be classified into three or more systems.

  Moreover, in the said embodiment, although the brake-by-wire using the fluid pressure is performed, it is not limited to this. Since it is only necessary to be able to control the braking force for the brake-by-wire, an electric brake that clamps the disc rotor with the brake pad or presses the brake shoe against the inner peripheral surface of the brake drum by controlling the driving of the electric actuator. Any brake may be used as long as it has an electronically controllable energy source such as a regenerative motor brake.

It is a schematic diagram which shows the circuit structure based on Embodiment based on this invention. It is a figure explaining the process of the brake controller which concerns on embodiment based on this invention. It is a figure which shows the relationship between the master cylinder pressure P and the contribution coefficient (alpha). It is a figure which shows the relationship between the master cylinder pressure P and the target deceleration Gp. It is a figure which shows the relationship between the depression stroke amount S and the target deceleration Gs. It is a schematic diagram for demonstrating the effect | action of this embodiment, Comprising: (a) shows a comparative example, (b) shows a present Example, respectively. It is a figure which shows the example of a time chart which concerns on embodiment based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 3FR-3RR Wheel cylinder 5-1 1st communication path 5-2 2nd communication path 6-1 and 6-2 Electromagnetic cutoff valve 7-1, 7-2 Motor (another drive source)
8-1, 8-2 Pump (another drive source)
9-1, 9-2 Actuator controller 22 Brake controller S Stepping stroke amount S0 Stepping stroke amount P when the shut-off valve is opened P Current master cylinder pressure P
P0 Minimum master cylinder pressure α with which basic contribution α is 1 Basic contribution degree k Master contribution k ′ Calculation contribution G Target deceleration Gp Temporary target deceleration Gs based on master cylinder pressure P Temporary target deceleration Gs Target deceleration L Stroke delay area

Claims (4)

A master cylinder that outputs a master cylinder pressure corresponding to the brake pedal depression stroke of the driver, and a target deceleration is calculated based on at least the master cylinder pressure of the master cylinder pressure and the brake pedal depression stroke amount. Braking control means for controlling the braking force of the wheel cylinder so as to be, and the contribution degree of the master cylinder pressure when calculating the target deceleration is set to increase as the master cylinder pressure increases, In the braking force control device,
The brake control means returns the brake pedal when it determines that the return operation of the brake pedal is performed in a state where the contribution degree of the master cylinder pressure is larger than the contribution degree of the stepping stroke amount when calculating the target deceleration. A braking force control device that restricts a decrease in the target deceleration when it is determined that the stroke is a stroke delay region where a delay has occurred.   2. The braking force control apparatus according to claim 1, wherein when the brake pedal is being returned and it is determined that the stroke delay region has been exceeded, the amount of restriction due to the reduction restriction is gradually reduced.   After limiting the reduction in the target deceleration, and before determining that the brake pedal is held or depressed before the brake pedal returns to the brake release position, the amount of restriction due to the reduction restriction is maintained. The braking force control apparatus according to claim 2. A master cylinder that outputs a master cylinder pressure corresponding to the brake pedal depression stroke of the driver, and a target deceleration is calculated based on at least the master cylinder pressure of the master cylinder pressure and the brake pedal depression stroke amount. And a braking control means for controlling the braking force of the wheel cylinder so that the degree of contribution of the master cylinder pressure when calculating the target deceleration is set to increase as the master cylinder pressure increases. In the braking force control device,
The braking control means determines that the master cylinder pressure is decreasing in a state where the contribution degree of the master cylinder pressure is larger than the contribution degree of the stepping stroke amount, and the return speed of the brake pedal with respect to the decreasing speed of the master cylinder pressure A braking force control device that restricts a decrease in the target deceleration when it is determined that the engine speed is small.

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