JP4360278B2 - Braking force control device for vehicle - Google Patents

Description

The present invention relates to a vehicle braking force control apparatus that performs anti-skid control on a hydraulic brake that generates a braking force in conjunction with a driver's braking operation.

Conventionally, as a first step toward full brake-by-wire, the front wheels rely on hydraulic brakes just like conventional brakes, while the rear wheels send electrical signals when the pedal is depressed to control the motor and brake the disc. There is a hybrid brake system that employs an electromechanical brake (brake-by-wire) that presses a pad (see Non-Patent Document 1).
“Automotive News” (USA), 2003-11-17, p. 22

By the way, in anti-skid control that detects the locking tendency of the wheel during braking and controls the hydraulic pressure, all inlet valves interposed between the master cylinder and each wheel cylinder are closed, and the hydraulic pressure of all the wheel cylinders is reduced. If the pressure cannot be increased, the driver will not be able to step on the brake pedal any more even if it is transient for a very short time. (Referred to as feeling). This step feeling occurs when the inlet valves of all the wheel cylinders are closed. Therefore, as in the conventional example described in Non-Patent Document 1 above, only the front wheels (two wheels) are used with a normal hydraulic brake. When configured, the probability that a stepped feeling of the pedal stroke will occur is much higher than when all of the front and rear wheels (four wheels) are configured with normal hydraulic brakes.
The present invention has been made paying attention to the above points, and when anti-skid control is performed on a hydraulic brake that generates a braking force in conjunction with a driver's brake operation, the step feeling of the brake operation is felt. It is an object to provide a vehicular braking force control device that can be reduced.

In order to solve the above-described problems, a vehicle braking force control apparatus according to the present invention includes a master cylinder that converts a driver's brake operation force into hydraulic pressure, and a wheel that generates braking force by hydraulic pressure from the master cylinder. Normal open type inlet valve that can close the cylinder, the flow path between the master cylinder and the wheel cylinder, the reservoir that communicates between the wheel cylinder and the inlet valve, and the normally closed that can open the flow path between the wheel cylinder and the reservoir A mold-type outlet valve and a normally-closed gate valve capable of opening a flow path communicating between the master cylinder and the reservoir,
Among one or more hydraulic brake systems composed of wheel cylinders, inlet valves, reservoirs, outlet valves, and gate valves, the inlet valves and outlet valves of the hydraulic brake system that detect the tendency of the wheels to lock due to braking When holding and depressurizing the hydraulic pressure of the wheel cylinder by driving control, when all the hydraulic brake system inlet valves are closed, at least one hydraulic brake system gate valve is opened. .

  According to the vehicle braking force control device of the present invention, when the inlet valves of all the hydraulic brake systems are closed, the gate valve of at least one hydraulic brake system is opened, thereby Since the hydraulic pressure can be flowed into the flow path communicating with the reservoir, the stepped feeling can be reduced even if the driver continues the brake operation. Therefore, the smaller the hydraulic brake system, such as a hybrid brake system composed of a hydraulic brake system and a brake-by-wire system, that is, the higher the probability that all the inlet valves of each hydraulic brake system will be closed, The invention becomes effective.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. The tandem master cylinder 2 that is interlocked with the operation of the brake pedal 1 converts the pedal effort of the driver into hydraulic pressure and supplies it to the left front wheel wheel cylinder 3FL and the right front wheel wheel cylinder 3FR. Between the brake pedal 1 and the master cylinder 2, for example, a vacuum servo type brake booster 4 that boosts the pedal effort by using the negative pressure of the engine is interposed. A front hydraulic pressure control circuit 6 is provided between the master cylinder 2 and the front wheel cylinders 3FL and 3FR. The front hydraulic pressure control circuit 6 is driven and controlled by the controller 5 to increase, hold and reduce the hydraulic pressure of the wheel cylinders 3FL and 3FR. It is disguised.

On the other hand, the rear hydraulic pressure control circuit 7 capable of generating an arbitrary hydraulic pressure is driven and controlled by the controller 5 and supplies hydraulic pressure corresponding to the driver's brake operation to the wheel cylinders 3RL and 3RR of the rear wheels.
That is, the front wheel side is configured by a hydraulic brake that generates a braking force using a hydraulic pressure as a transmission medium from a mechanical operation of the brake pedal 1 by the driver, and one rear wheel side has a braking force corresponding to the driver's braking operation. It is a hybrid brake system composed of brake-by-wire that performs control.
Each of the wheel cylinders 3FL to 3RR is incorporated in a disc brake that presses a disc rotor with a brake pad to generate a braking force, or a drum brake that generates a braking force by pressing a brake shoe against the inner peripheral surface of the brake drum. Yes.

  The front hydraulic pressure control circuit 6 detects not only the anti-skid control (ABS) that controls the hydraulic pressure of the wheel cylinders 3FL and 3FR by detecting the tendency of the wheels to be locked by braking, but also the traction control that suppresses wheel spin during acceleration ( TCS) and a braking fluid pressure control circuit capable of controlling vehicle dynamics control (VDC: Vehicle Dynamics Control) that suppresses side slip when turning, as shown in FIG. 2, a master cylinder 2 and a wheel cylinder 3FL Normally open type first gate valve 8FL (8FR) capable of closing the flow path between (3FR) and normally open capable of closing the flow path between the first gate valve 8FL (8FR) and the wheel cylinder 3FL (3FR) Type inlet valve 9FL (9FR) and wheel cylinder 3FL (3FR) A reservoir 10FL (10FR) communicated between the valve 9FL (9FR), a normally closed outlet valve 11FL (11FR) capable of opening a flow path between the wheel cylinder 3FL (3FR) and the reservoir 10FL (10FR), and a master cylinder A normally closed second gate valve 12FL (12FR) that can open a flow path that communicates between the first and second gate valves 8FL (8FR) and the reservoir 10FL (10FR) and the outlet valve 11FL (11FR); A positive displacement pump 13f having a suction side communicated between the 10FL (10FR) and the outlet valve 11FL (11FR) and a discharge side communicated between the first gate valve 8FL (8FR) and the inlet valve 9FL (9FR); I have. Here, the second gate valves 12FL and 12FR correspond to “gate valves”. Incidentally, on the discharge side of the pump 13f, a damper chamber 14f that suppresses the pulsation of the discharged brake fluid and weakens the pedal vibration is disposed.

  The first gate valves 8FL and 8FR, the inlet valves 9FL and 9FR, the outlet valves 11FL and 11FR, and the second gate valves 12FL and 12FR are two-port, two-position switching, single solenoid, and spring offset type electromagnetic operation valves, respectively. The first gate valves 8FL and 8FR and the inlet valves 9FL and 9FR open the flow path at the non-excited normal position, and the outlet valves 11FL and 11FR and the second gate valves 12FL and 12FR are at the non-excited normal position. The flow path is closed. Further, the reservoirs 10FL and 10FR are constituted by spring-shaped reservoirs in which a compression spring is opposed to a piston of a cylinder. The spring chamber side is open to the atmosphere, and the spring is a weak spring that returns the piston. The pump 13f is a positive displacement pump such as a gear pump, a vane pump, a piston pump or the like that can ensure a substantially constant discharge amount regardless of the load pressure.

With the above configuration, when the first gate valve 8FL (8FR), the inlet valve 9FL (9FR), the outlet valve 11FL (11FR), and the second gate valve 12FL (12FR) are all in the non-excited normal position, The hydraulic pressure from the cylinder 2 is supplied as it is to the wheel cylinder 3FL (3FR) and becomes a normal brake.
Further, when the first gate valve 8FL (8FR), the outlet valve 11FL (11FR), and the second gate valve 12FL (12FR) are in the non-excited normal position, the inlet valve 9FL (9FR) is excited and closed. The flow paths from the wheel cylinder 3FL (3FR) to the master cylinder 2 and the reservoir 10FL (10FR) are blocked, and the hydraulic pressure of the wheel cylinder 3FL (3FR) is maintained.

  Further, when the first gate valve 8FL (8FR) and the second gate valve 12FL (12FR) are in the non-excited normal position, the inlet valve 9FL (9FR) is excited and closed, and the outlet valve 11FL (11FR) is closed. Is excited and released, the hydraulic pressure of the wheel cylinder 3FL (3FR) flows into the reservoir 10FL (10FR) and is reduced. The hydraulic pressure flowing into the reservoir 10FL (10FR) is sucked by the pump 13f and returned to the master cylinder 2.

  Therefore, the controller 5 uses the brake of the hydraulic brake system 15L for the left front wheel and the hydraulic brake system 15R for the right front wheel, which includes the first gate valve, the inlet valve, the outlet valve, the second gate valve, and the pump. Drives and controls the inlet valve, outlet valve, and pump of the hydraulic brake system that detects the tendency of the wheel to lock, thereby increasing, maintaining, and reducing the hydraulic pressure in the wheel cylinder.

  The first gate valves 8FL and 8FR and the second gate valves 12FL and 12FR are not used in the anti-skid control, but are required in the traction control and the stability control. For example, even when the brake pedal 1 is not operated, the first gate valve 8FL (8FR) is energized while the inlet valve 9FL (9FR) and the outlet valve 11FL (11FR) are in the non-excited normal position. In addition to closing, the second gate valve 12FL (12FR) is excited and opened, and the pump 13f is further driven to suck and discharge the hydraulic pressure of the master cylinder 2 through the second gate valve 12FL (12FR). The supplied hydraulic pressure can be supplied to the wheel cylinder 3FL (3FR) via the inlet valve 9FL (9FR) to increase the pressure.

  Next, the rear hydraulic pressure control circuit 7 is the same as the front hydraulic pressure control circuit 6 except that the master cylinder 2 of the front hydraulic pressure control circuit 6 is replaced with a reservoir tank 16 that simply stores brake fluid. The first gate valves 8RL and 8RR, the inlet valves 9RL and 9RR, the outlet valves 11RL and 11RR, the second gate valves 12RL and 12RR, the pump 13r, and the damper chamber 14r are not described in detail. Further, regarding the drive control of the left rear wheel brake-by-wire system 17L and the right rear wheel brake-by-wire system 17R including the first gate valve, the inlet valve, the outlet valve, the second gate valve, and the pump, the wheel cylinder When increasing the hydraulic pressure of 3RL / 3RR, it is the same as when increasing the pressure by traction control or stability control, and when maintaining / reducing the hydraulic pressure of the rear wheel cylinder 3RL / 3RR, anti-skid Since it is the same as that at the time of holding and depressurization by control, detailed description thereof is also omitted.

  As shown in FIG. 1, the controller 5 includes a master cylinder pressure Pm detected by the pressure sensor 18, a rear wheel wheel cylinder pressure Pr detected by the pressure sensor 19, and each wheel speed Vwi (i detected by the wheel rotation sensor 20. = FL, FR, RL, RR), the BBW control processing of FIG. 3 for the rear wheels, the ABS control processing of FIG. 4 for the front and rear wheels, and the gate valve control processing of FIGS. 5 and 6 for the front wheels. Execute.

First, the BBW control process executed by the controller 5 will be described based on the flowchart of FIG.
The BBW control process is executed as a timer interruption process every predetermined time (for example, 10 msec). First, in step S1, a front wheel braking force Ff is calculated from the master cylinder pressure Pm as shown in the following equation (1). Here, k1 is a coefficient.
Ff = k1 × Pm (1)

In the subsequent step S2, as shown in the following equation (2), the vehicle braking force Ftotal is calculated according to the master cylinder pressure Pm.
Ftotal = f (Pm) (2)
In the subsequent step S3, as shown in the following equation (3), the front wheel braking force Ff is subtracted from the vehicle braking force Ftotal to calculate the rear wheel target braking force Fr.
Fr = Ftotal−Ff (3)
In the subsequent step S4, the rear wheel target braking force Fr is output to the BBW actuator 7 as a braking force command value, and then the routine returns to a predetermined main program.

Next, the ABS control process executed by the controller 5 will be described based on the flowchart of FIG.
The ABS control process is executed as a timer interrupt process for every predetermined time (for example, 10 msec). First, in step S11, the vehicle body speed V is estimated based on any of the select high, select second, average value, etc. of each wheel speed Vwi. Then, as shown in the following equation (4), the slip ratio Si of each wheel is calculated.
Si = (V−Vwi) / V (4)

  In subsequent step S12, it is determined whether or not each slip ratio Si is equal to or greater than a predetermined value Sa. When the determination result is Si <Sa, it is determined that the wheel does not have a tendency to lock, and the process proceeds to step S13. After the ABS is deactivated, the process returns to the predetermined main program.

On the other hand, when the determination result is Si ≧ Sa, it is determined that the wheel tends to be locked, and the process proceeds to step S14, where the difference between the actual slip ratio Si and the target slip ratio S ^* (for example, about 10%) is obtained. Accordingly, a target value of each wheel cylinder pressure is calculated, and the front hydraulic pressure control circuit 6 and the rear hydraulic pressure control circuit 7 are driven and controlled based on this target value, and then the ABS is activated and a predetermined main program is executed. Return to.

Next, the gate valve control process executed by the controller 5 will be described based on the flowcharts of FIGS.
The gate valve control process is executed as a timer interruption process every predetermined time (for example, 10 msec). First, in step S31, the pedal stroke speed Vp is calculated according to the increasing speed of the master cylinder pressure Pm.

In the subsequent step S32, the target flow rate of the brake fluid flowing out from the master cylinder 2 to the reservoir 10j (j = FL, FR) necessary to maintain the pedal stroke speed Vp when the second gate valves 12FL and 12FR are opened. W _AM j is calculated according to the pedal stroke speed Vp as shown in the following equation (5). Here, Dm is the piston diameter of the master cylinder 2.
W _AM j = (π / 4) × Dm ² × Vp (5)

In the subsequent step S33, when the second gate valve 12FL / 12FR is opened, the target flow rate Q _AM j of the brake fluid flowing out from the master cylinder 2 to the reservoir 10j is calculated during the calculation period (10 msec) of the gate valve control process. As shown in the following formula (6), calculation is performed according to the target flow velocity W _AM j. Although the calculation cycle is 10 msec here, it may be within a time during which the stepped feeling can be reduced.
Q _AM j = ∫ (W _AM j) dt (6)

In a succeeding step S34, it is determined whether or not the ABS is operating on the front wheels. If the ABS is operating on the front wheels, the process proceeds to step S37 described later. If the ABS is not operating, the process proceeds to step S35.
In step S35, it is determined that the ABS is inactive and the interior of the reservoir 10j is empty, and the reservoir fluid pressure Paj and the reservoir fluid amount Qaj are set to 0 as shown in the following equation (7).
Paj = 0
Qaj = 0 ......... (7)

In the subsequent step S36, since the ABS is in a non-actuated state and becomes a normal brake, the master cylinder pressure Pm is set to the wheel cylinder pressure Pwj as shown in the following equation (8), and the control map of FIG. The wheel cylinder fluid amount Qwj is calculated from the wheel cylinder pressure Pwj, and the process returns to a predetermined main program. The control map of FIG. 7 is set so that the wheel cylinder fluid amount Qw increases as the wheel cylinder pressure Pw increases.
Pwj = Pm (8)

  On the other hand, in step S37 which shifts from step S34, it is determined whether or not the ABS operation is pressure increase control. When the ABS operation is the pressure increase control, the process proceeds to step S38, and as shown in the equation (8), the master cylinder pressure Pm is set to the wheel cylinder pressure Pwj, and the control map of FIG. The wheel cylinder fluid amount Qwj is calculated from the wheel cylinder pressure Pwj.

On the other hand, when the ABS operation is not the pressure increase control, the process proceeds to step S39, and it is determined whether or not the pressure reduction control is performed. When the ABS operation is pressure reduction control, the routine proceeds to step S42, which will be described later.
In step S40, there is no increase or decrease in the fluid pressure and fluid volume of the wheel cylinder 3j due to the holding control, so the value Pwj _(n-1) before one sampling is set to the wheel cylinder pressure Pwj as shown in the following equation (9). At the same time, the value Qwj _(n-1) before one sampling is set to the wheel cylinder fluid amount Qwj.
Pwj = Pwj _(n-1)
Qwj = Qwj _(n-1) ......... (9)

In step S41 following step S38 or S40, the pump drive by the pressure reduction control is not performed, and the fluid pressure and the fluid volume of the reservoir 10j do not increase or decrease. Therefore, as shown in the following equation (10), the reservoir pressure Paj is and sets one sampling previous value Paj the _(n-1), by setting the reservoir fluid Qaj one sampling previous value Qaj _(n-1), the process proceeds to step S50 of FIG. 6 to be described later.
Paj = Paj _(n-1)
Qaj = Qaj _(n-1) (10)

On the other hand, in step S42 that moves from step S39, as shown in the following equation (11), a differential pressure ΔP _AW j between the reservoir 10j and the wheel cylinder 3j is calculated.
ΔP _AW j = Pwj _(n−1) −Paj _(n−1) (11)
In the subsequent step S43, referring to the control map of FIG. 8, when the outlet valve 11j is opened by the pressure reduction control, the brake fluid that flows out from the wheel cylinder 3j to the reservoir 10j during the calculation period (10 msec) of the gate valve control process. the flow rate W _AW j, is calculated in accordance with the differential pressure [Delta] P _AW j. This control map is set so that the flow velocity W _AW j increases as the differential pressure ΔP _AW j increases.

In the following step S44, when the outlet valve 11j is opened by the pressure reduction control, the flow rate Q _AW j of the brake fluid flowing out from the wheel cylinder 3j to the reservoir 10j during the calculation period (10 msec) of the gate valve control process is As shown in the equation (12), calculation is performed according to the flow velocity W _AW j.
Q _AW j = ∫ (W _AW j) dt (12)

In the subsequent step S45, the brake fluid corresponding to the flow rate Q _AW j has flowed out of the wheel cylinder 3j due to the pressure reduction control. Therefore, as shown in the following equation (13), the wheel cylinder fluid amount Qwj is set to the value Qwj before one sampling. A value obtained by subtracting the flow rate Q _AW j from _(n-1) is calculated, and the wheel cylinder pressure Pwj is calculated from the wheel cylinder fluid amount Qwj with reference to the control map of FIG.
Qwj = Qwj _(n-1) −Q _AW j (13)

In the following step S46, as shown in the following equation (14), the flow rate Q _AP j of the brake fluid that has flowed out of the reservoir 10j by the pump drive by the pressure reduction control is calculated according to the pump rotational speed Np. Here, Qp is the discharge amount for one rotation of the pump. Since the master cylinder pressure Pm pulsates as the pump 13f is driven, the pulsation cycle of the master cylinder pressure Pm may be used instead of the pump rotation speed Np.
Q _AP j = Np × Qp (14)

In the subsequent step S47, the brake fluid corresponding to the flow rate Q _AW j flows into the reservoir 10j and the brake fluid corresponding to the flow rate Q _AP j flows out of the reservoir 10j. The liquid amount Qaj is set to a value obtained by subtracting the flow rate Q _AP j from the flow rate Q _AW j, and the reservoir fluid pressure Paj is calculated from the reservoir fluid amount Qaj by referring to the control map of FIG. The process proceeds to step S50. This control map is set so that the reservoir fluid pressure Pa increases as the reservoir fluid amount Qa increases.
Qaj = Q _AW j−Q _AP j (15)

In step S50 of FIG. 6 which shifts from the step S41 or S47, it is determined whether or not all the inlet valves 9FL and 9FR are closed by the ABS operation. If either one of the inlet valves 9FL and 9FR is opened, the process proceeds to step S51, the second gate valves 12FL and 12FR are closed, and the process returns to a predetermined main program.
On the other hand, if all the inlet valves 9FL and 9FR are closed, the process proceeds to step S52, and the road surface friction coefficient μ is calculated based on the slip ratio Sj of the front wheels and the brake operation amount (master cylinder pressure Pm).

  In a succeeding step S53, it is determined whether or not the road surface friction coefficient μ is not less than a predetermined value. Here, the predetermined value for the road surface friction coefficient μ is a threshold value for determining whether or not a large pressure reduction due to the ABS operation is necessary. That is, when the road surface friction coefficient μ is less than a predetermined value, it is determined that a large pressure reduction due to the ABS operation is necessary, and the process proceeds to the step S51. If not, the process proceeds to step S54.

In step S54, referring to the control map of FIG. 10, the target flow rate Q _AM j is limited according to the sum of the reservoir fluid amounts Qaj. This control map shows that the target flow rate Q _AM j decreases as the sum of the reservoir fluid amounts Qaj approaches the maximum capacity Qa _MAX for two reservoirs, and the sum of the reservoir fluid amounts Qaj reaches 80% of the maximum capacity Qa _MAX. Sometimes the target flow rate Q _AM j is set to be zero.
In the subsequent step S55, the ratio K between the reservoir fluid amounts Qaj is calculated as shown in the following equation (16).
K = 2 × QaFL / (QaFL + QaFR) (16)

In step S56, as shown in the following equation (17), corrects the target flow rate Q _AM FL · Q _AM FR in accordance with the ratio K between the reservoir fluid QaFL · QaFR.
Q _AM FL = (2-K) × Q _AM FL
Q _AM FR = K × Q _AM FR (17)
According to the above equation (16), for example, when the reservoir liquid amount QaFL is larger than QaFR, the ratio K is larger than 1, so if this is substituted into the above equation (17), the liquid amount is relatively large. QaFL is adjusted to a small value, and conversely, QaFR having a relatively small liquid volume is adjusted to a large value.

In the subsequent step S57, the stroke amount S of the brake pedal 1 is calculated from the master cylinder pressure Pm.
In the subsequent step S58, the target flow rate Q _AM j is limited according to the stroke amount S of the brake pedal 1 with reference to the control map of FIG. The control map is to reduce the target flow rate Q _AM j as stroke amount S approaches a maximum value S _MAX, target flow rate Q _AM j is 0 when the pedal stroke amount S reaches 80% of the maximum value S _MAX Is set to
In subsequent step S59, as shown in the following equation (18), a differential pressure ΔP _AM j between the master cylinder 2 and the reservoir 10j is calculated.
ΔP _AM j = Pm−Paj (18)

In the subsequent step S60, the duty ratio for opening the second gate valves 12FL and 12FR is calculated according to the target flow rate Q _AM j and the differential pressure ΔP _AM j with reference to the control map of FIG. The control map is increased as the duty ratio target flow rate Q _AM is increased is set to higher differential pressure [Delta] P _AM is greater rate of increase increases. The relationship between the duty ratio and the valve opening is set so that the valve opening increases as the duty ratio increases, as shown in FIG.

In the subsequent step S61, the second gate valves 12FL and 12FR are opened according to the duty ratio.
In the subsequent step S62, when the second gate valves 12FL and 12FR are opened, the brake fluid for the target flow rate Q _AM j flows into the reservoir 10j. Therefore, as shown in the following equation (19), the reservoir fluid amount Qaj A value obtained by adding the target flow rate Q _AM j to the value is set as a new reservoir fluid amount Qaj, and referring to the control map of FIG. 9 described above, the reservoir fluid pressure Paj is calculated from the new reservoir fluid amount Qaj, Return to the predetermined main program.

  As described above, the ABS control process of FIG. 4 corresponds to the “anti-skid control means”. 5 and 6, the process at step S31 corresponds to “operation speed detection means”, the processes at steps S34 to S47 and S62 correspond to “reservoir liquid amount detection means”, and the process at step S52 is “ Corresponding to the “road surface friction coefficient detecting means”, the processing in step S57 corresponds to “brake operation amount detecting means”, and the gate valve control processing excluding these steps S31, S34 to S47, S62, S52, S57 is “gate”. It corresponds to “valve control means”.

Next, the operation and effects of the one embodiment will be described.
In the anti-skid control in which the hydraulic pressure is controlled by detecting the wheel locking tendency during braking, as shown in FIG. 14, the inlet valves 9FL and 9FR interposed between the master cylinder 2 and the wheel cylinders 3FL and 3FR are controlled. If both sides are closed and the wheel cylinders 3FL and 3FR cannot be increased in pressure, the driver will not be able to step on the brake pedal any further, but will be unable to step on the brake pedal. A sense of incongruity that is stepped, that is, a stepped feeling, occurs.

  Therefore, when both the inlet valves 9FL and 9FR are closed by the operation of the ABS (the determination in step S50 is “Yes”), and the road surface friction coefficient μ is greater than or equal to the predetermined value (the determination in step S53 is “Yes”). As shown in FIG. 15, the second gate valves 12FL and 12FR are opened (step S61). As a result, the hydraulic pressure from the master cylinder 2 can flow into the flow path communicating with the reservoirs 10FL and 10FR, and the stepped feeling can be reduced even if the driver continues the brake operation. This stepped feeling is generated when the inlet bubbles of all the wheel cylinders are closed. Therefore, as in the above-described embodiment, the hydraulic brake systems 15L and 15R for the front wheels and the brake-by-wire systems 17L and 17R for the rear wheels are used. The present invention is more effective when the number of hydraulic brake systems is smaller, such as the hybrid brake system, that is, the higher the probability that all the inlet valves of each hydraulic brake system are closed.

  Further, when the capacity of the reservoirs 10FL and 10FR is saturated due to the inflow of the hydraulic pressure from the master cylinder 2, when a large pressure reduction is required for the ABS operation, the wheel cylinders 3FL and 3FR can be operated even if the outlet valves 11FL and 11FR are opened. The hydraulic pressure cannot be reduced. Therefore, when the road surface friction coefficient μ is less than the predetermined value, the second gate valves 12FL and 12FR are closed, and a sufficient hydraulic pressure inflow allowance can be secured in the reservoirs 10FL and 10FR.

When the second gate valves 12FL and 12FR are opened, the target flow rate Q _AM j of the brake fluid that passes through the second gate valves 12FL and 12FR and flows into the reservoirs 10FL and 10FR from the master cylinder 2 is determined by the pedal stroke. It is determined by the speed Vp, the sum of the reservoir fluid amounts QaFL and QaFR, the ratio K between the reservoir fluid amounts, and the pedal stroke amount S.

That is, the higher the pedal stroke speed Vp, the larger the target flow rate Q _AM j and the more open the second gate valves 12FL and 12FR (steps S32 and S33). The feeling of sticking can be effectively reduced. In addition, since the target flow rate Q _AM j is set to a value necessary to maintain the pedal stroke speed Vp, there is too much flow passing through the second gate valves 12FL and 12FR, and the pedal stroke increases rapidly. A sense of incongruity (such as when the pedal reaction force is lost) can be suppressed.

Further, as the total sum of the reservoir fluid amounts Qaj is larger, the target flow rate Q _AM j is decreased to reduce the open state of the second gate valves 12FL and 12FR (step S54), and therefore the reservoirs 10FL and 10FR are configured. A sufficient hydraulic pressure inflow allowance can be secured for the wheel cylinder as described above, even if the reservoir capacity is saturated by the inflow of the hydraulic pressure from the master cylinder 2 and the outlet valve is opened by the ABS operation. A situation in which the pressure cannot be reduced can be avoided.

Further, the ratio K between the reservoir fluid amounts is calculated (step S55), and the target flow rate _QAM with the relatively large reservoir fluid amount is adjusted to a small value. since the target flow rate Q _AM is configured to adjust to a large value (step S56), maintaining the balance between the reservoir fluid, the capacity of one of the reservoir is saturated earlier than the other, the outlet of ABS operation It is possible to avoid a situation in which the wheel cylinder pressure cannot be reduced even when the valve is opened.

Further, as the pedal stroke amount S is increased, the target flow rate Q _AM j is decreased to reduce the open state of the second gate valves 12FL and 12FR (step S58). It is possible to suppress a so-called solid stepping state in which the brake pedal 2 is stepped down to the mechanical maximum stroke position in a state where the increase is suppressed. Further, since the pedal reaction force increases as the brake pedal 2 is depressed even in the normal brake, the larger the pedal stroke amount S, the smaller the target flow rate Q _AM j and the smaller the open state of the second gate valve, The pedal reaction force can be increased, and a more natural pedal feeling can be produced.

  In the above-described embodiment, in order to determine whether or not the second gate valves 12FL and 12FR are opened, it is determined whether or not the road surface friction coefficient μ is greater than or equal to a predetermined value in step S53. However, the present invention is not limited to this. For example, the rate of decrease of the road surface friction coefficient μ is calculated, and when the rate of decrease of the road surface friction coefficient μ is equal to or greater than a predetermined value, it is determined that the pressure reduction due to the ABS operation is immediately started, and In order to secure the hydraulic pressure inflow allowance, the second gate valves 12FL and 12FR may be closed. In this case, the process of calculating the decrease speed of the road surface friction coefficient μ corresponds to the “decrease speed detecting means”. Of course, whether or not to open the second gate valves 12FL and 12FR may be determined according to both the road surface friction coefficient μ and the decreasing speed thereof.

In the above embodiment, the second gate valves 12FL and 12FR are closed when the road surface friction coefficient μ is less than a predetermined value in the process of step S53. However, the present invention is not limited to this. . That is, as in the case of the sum of the reservoir fluid amount Qaj and the pedal stroke amount S, the lower the road surface friction coefficient μ, the smaller the target flow rate Q _AM j and the smaller the open state of the second gate valves 12FL and 12FR. Also good.

Further, in the above-described embodiment, the target flow rate Q _AM j is decreased to decrease the open state of the second gate valves 12FL and 12FR as the sum of the reservoir fluid amounts Qaj is increased in the process of step S54. However, the present invention is not limited to this. That is, the open state of the second gate valves 12FL and 12FR is not gradually reduced in accordance with the sum of the reservoir fluid amount Qaj, but the sum of the reservoir fluid amounts Qaj is equal to or greater than a predetermined value as in the case of the road surface friction coefficient μ. The second gate valves 12FL and 12FR may be closed only when

Furthermore, in the above-described embodiment, as the pedal stroke amount S is increased in the process of step S58, the target flow rate Q _AM j is decreased to reduce the open state of the second gate valves 12FL and 12FR. It is not limited to this. That is, according to the pedal stroke amount S, the open state of the second gate valves 12FL and 12FR is not gradually reduced, but only when the pedal stroke amount S is equal to or greater than a predetermined value, as in the case of the road surface friction coefficient μ. The second gate valves 12FL and 12FR may be closed.

Furthermore, in the above-described embodiment, the target flow rate Q _AM j is adjusted according to the ratio K between the reservoir fluid amounts in the process of step S55, but is not limited to this. For example, to calculate the ratio between the right and left road surface friction coefficient mu, and adjust the target flow rate Q _AM road friction coefficient mu is relatively lower to a small value, contrary to the road surface friction coefficient mu is relatively higher the target flow rate Q _AM may be adjusted to a large value.

In the above-described embodiment, the road surface friction coefficient μ is calculated based on the front wheel slip ratio Sj and the brake operation amount (master cylinder pressure Pm) in step S52. However, the present invention is not limited to this. For example, road surface conditions such as rainy roads, snow roads, and frozen roads are determined based on road surface image data and temperature, or detected using a road surface detection sensor (GVS: Grand View Censor), May be obtained from the infrastructure or the road surface friction coefficient μ may be estimated.
In the above-described embodiment, the spring-shaped reservoir is used. However, the present invention is not limited to this, and any type of reservoir may be used as long as it has a function of storing brake fluid.

  In the above embodiment, the first gate valves 8FL to 8RR and the inlet valves 9FL to 9RR open the flow path at the non-excited normal position, and the outlet valves 11FL to 11RR and the second gate valves 12FL to 12RR are opened. The flow path is closed at the non-excited normal position, but the present invention is not limited to this. In short, since it is only necessary to open and close each valve, the first gate valves 8FL to 8RR and the inlet valves 9FL to 9RR open the flow path at the excited offset position, and the outlet valves 11FL to 11RR and the second gate are opened. The valves 12FL to 12RR may close the flow path at the excited offset position.

In the above embodiment, when the second gate valves 12FL and 12FR are driven and controlled in the process of step S61, the valve opening is controlled according to the duty ratio. However, the present invention is not limited to this. Instead, the time for simply closing and the time for opening may be controlled.
In the above embodiment, the master cylinder pressure Pm is used when the pedal stroke speed Vp is calculated in step S31, and when the pedal stroke amount S is calculated in the process of step S57. Of course, a stroke sensor may be provided to detect the operation speed and the operation amount of the brake pedal 1.

Further, the wheel cylinder pressure Pw and the reservoir pressure Pa are calculated in the processes of steps S34 to S47 and S62. However, the present invention is not limited to this. Of course, a pressure sensor is provided to provide the wheel cylinder pressure Pw and the reservoir pressure Pa. Pa may be detected.
Further, in the above-described embodiment, the front hydraulic pressure control circuit 6 that can perform not only anti-skid control but also traction control and stability control is adopted. However, in the present invention, it is only necessary to be able to perform anti-skid control. The first gate valves 8FL and 8FR may be omitted. Incidentally, a general hydraulic pressure control circuit that performs anti-skid control is not provided with the second gate valves 12FL and 12FR. Therefore, when a hydraulic pressure control circuit dedicated to anti-skid control is used, the It is necessary to provide a two-gate valve.

  In the above embodiment, the rear hydraulic pressure control circuit 7 supplies the hydraulic pressure to the wheel cylinder to generate the braking force, but the present invention is not limited to this. For example, an electric brake that drives and controls the electric actuator and clamps the disk rotor with a brake pad (or presses a brake shoe against the inner peripheral surface of the brake drum), a regenerative motor brake, or the like may be used. In short, since it is only necessary to be able to control the braking force by brake-by-wire, any brake may be used as long as it has an electronically controllable energy source.

Further, in the above-described embodiment, the front hydraulic pressure control circuit 6 and the rear hydraulic pressure control circuit 7 are configured separately, but may be integrated.
Further, in the above-described embodiment, the front wheel side is the hydraulic brake system 15L / 15R, and the rear wheel side is the brake-by-wire system 17L / 17R. However, the present invention is not limited to this, and the front wheel side is the brake-by-wire system. The rear wheel side may be a hydraulic brake system. Furthermore, the front / rear split system is used in which the hydraulic brake system 15L / 15R and the brake-by-wire system 17L / 17R are divided by the front and rear wheels, but the present invention is not limited to this, and the left front wheel, right rear wheel and right front wheel are not limited thereto. In addition, a diagonal split system that divides the vehicle by the left rear wheel may be employed.

  Further, in the above-described embodiment, the front wheel braking force Ff and the vehicle braking force Ftotal are calculated according to the master cylinder pressure Pm in the process of step S1, but the present invention is not limited to this. You may detect from the operation amount. Further, although the rear wheel target braking force Fr is calculated by subtracting the front wheel braking force Ff from the vehicle braking force Ftotal in the process of step S3, the present invention is not limited to this and is calculated according to the driver's brake operation. Since it may be possible, it may be calculated from the master cylinder pressure Pm and the operation amount (stroke or pedaling force) of the brake pedal 1.

Further, in the above-described embodiment, the hybrid brake system of the hydraulic brake systems 15L and 15R and the brake-by-wire systems 17L and 17R is adopted. However, the present invention is not limited to this, and all the brake systems are hydraulic brakes. You may comprise by a system | strain. However, the present invention is more effective as the number of hydraulic brake systems is smaller, that is, the higher the probability that all the inlet valves of each hydraulic brake system are closed.
Furthermore, in the above-described embodiment, the present invention is applied to a four-wheeled vehicle, but may be applied to a two-wheeled vehicle, a three-wheeled vehicle, or a vehicle having five or more wheels.

It is a schematic structure figure showing an embodiment of the present invention. It is a hydraulic control circuit. It is a flowchart which shows a BBW control process. It is a flowchart which shows an ABS control process. It is a flowchart which shows a gate valve control process (first half). It is a flowchart which shows a gate valve control process (second half). It is a control map which shows the relationship between the liquid quantity and hydraulic pressure of a wheel cylinder. It is a control map used for calculation of flow velocity _WAW . It is a control map which shows the relationship between the liquid quantity of a reservoir, and a hydraulic pressure. It is a control map used for the restriction _| limiting of the target flow volume QAM. It is a control map used for the restriction _| limiting of the target flow volume QAM. It is a control map used for calculation of Duty ratio. It is a graph which shows the relationship between Duty ratio and valve opening. It is a time chart which shows the conventional problem. It is a time chart which shows the effect of this invention.

Explanation of symbols

1 Brake Pedal 2 Master Cylinder 3FL / 3FR Front Wheel Cylinder 3RL / 3RR Rear Wheel Cylinder 4 Brake Booster 5 Controller 6 Front Fluid Pressure Control Circuit 7 Rear Fluid Pressure Control Circuit 8FL / 8FR First Gate Valve 9FL / 9FR Inlet Valve 10FL / 10FR reservoir 11FL / 11FR outlet valve 12FL / 12FR second gate valve 13f pump 14f damper chamber 15L / 15R hydraulic brake system 17L / 17R brake-by-wire system 18/19 pressure sensor 20 wheel rotation sensor

Claims (12)

A master cylinder that converts the brake operation force of the driver into hydraulic pressure, a wheel cylinder that generates braking force by the hydraulic pressure from the master cylinder, and a normal open that can close the flow path between the master cylinder and the wheel cylinder Between the wheel cylinder and the inlet valve, a normally closed outlet valve capable of opening a flow path between the wheel cylinder and the reservoir, and between the master cylinder and the reservoir A normally-closed gate valve that can open the communication channel;
Of the one or more hydraulic brake systems configured by the wheel cylinder, the inlet valve, the reservoir, the outlet valve, and the gate valve, the hydraulic brake system that detects the tendency of the wheel to be locked by braking is detected. Anti-skid control means for driving and controlling the inlet valve and the outlet valve to maintain and reduce the hydraulic pressure of the wheel cylinder;
When the anti-skid control means closes the inlet valves of all the hydraulic brake systems, the gate valve control means for opening the gate valves of at least one of the hydraulic brake systems, and the fluid flowing into the reservoir A reservoir fluid amount detecting means for detecting the amount,
The vehicular braking force control device according to claim 1, wherein the gate valve control means reduces the open state of the gate valve as the amount of the liquid in the reservoir detected by the reservoir liquid amount detection means increases . A master cylinder that converts the brake operation force of the driver into hydraulic pressure, a wheel cylinder that generates braking force by the hydraulic pressure from the master cylinder, and a normal open that can close the flow path between the master cylinder and the wheel cylinder Between the wheel cylinder and the inlet valve, a normally closed outlet valve capable of opening a flow path between the wheel cylinder and the reservoir, and between the master cylinder and the reservoir A normally-closed gate valve that can open the communication channel;
Of the one or more hydraulic brake systems configured by the wheel cylinder, the inlet valve, the reservoir, the outlet valve, and the gate valve, the hydraulic brake system that detects the tendency of the wheel to be locked by braking is detected. Anti-skid control means for driving and controlling the inlet valve and the outlet valve to maintain and reduce the hydraulic pressure of the wheel cylinder;
When the anti-skid control means closes the inlet valves of all the hydraulic brake systems, the gate valve control means that opens the gate valves of at least one of the hydraulic brake systems, and detects the friction coefficient of the road surface Road surface friction coefficient detecting means
The vehicular braking force control apparatus according to claim 1, wherein the gate valve control means reduces the open state of the gate valve as the road surface friction coefficient detected by the road surface friction coefficient detection means decreases . A master cylinder that converts the brake operation force of the driver into hydraulic pressure, a wheel cylinder that generates braking force by the hydraulic pressure from the master cylinder, and a normal open that can close the flow path between the master cylinder and the wheel cylinder Between the wheel cylinder and the inlet valve, a normally closed outlet valve capable of opening a flow path between the wheel cylinder and the reservoir, and between the master cylinder and the reservoir A normally-closed gate valve that can open the communication channel;
Of the one or more hydraulic brake systems configured by the wheel cylinder, the inlet valve, the reservoir, the outlet valve, and the gate valve, the hydraulic brake system that detects the tendency of the wheel to be locked by braking is detected. Anti-skid control means for driving and controlling the inlet valve and the outlet valve to maintain and reduce the hydraulic pressure of the wheel cylinder;
When the anti-skid control unit closes the inlet valve of all the hydraulic brake system, and the gate valve control means for opening the gate valve at least one of the hydraulic brake system, the rate of decrease in road surface friction coefficient A reduction speed detecting means for detecting
The vehicular braking force control apparatus according to claim 1, wherein the gate valve control means reduces the open state of the gate valve as the reduction speed of the road surface friction coefficient detected by the reduction speed detection means increases . A master cylinder that converts the brake operation force of the driver into hydraulic pressure, a wheel cylinder that generates braking force by the hydraulic pressure from the master cylinder, and a normal open that can close the flow path between the master cylinder and the wheel cylinder Between the wheel cylinder and the inlet valve, a normally closed outlet valve capable of opening a flow path between the wheel cylinder and the reservoir, and between the master cylinder and the reservoir A normally-closed gate valve that can open the communication channel;
Of the one or more hydraulic brake systems configured by the wheel cylinder, the inlet valve, the reservoir, the outlet valve, and the gate valve, the hydraulic brake system that detects the tendency of the wheel to be locked by braking is detected. Anti-skid control means for driving and controlling the inlet valve and the outlet valve to maintain and reduce the hydraulic pressure of the wheel cylinder;
When the anti-skid control means closes the inlet valves of all the hydraulic brake systems, the gate valve control means for opening the gate valves of at least one of the hydraulic brake systems, and a brake operation amount are detected. A brake operation amount detection means,
The vehicular braking force control device according to claim 1, wherein the gate valve control means reduces the open state of the gate valve as the brake operation amount detected by the brake operation amount detection means increases . A hybrid brake system comprising the hydraulic brake system and a brake-by-wire system that calculates a target braking force according to a driver's brake operation and performs a braking force control according to the target braking force, The vehicular braking force control apparatus according to any one of claims 1 to 4 . Having an operation speed detecting means for detecting the operation speed of the brake operation;
The gate valve control means, the faster the operating speed of the detected braking operation by the operating speed detecting means, according to any one of claims 1 to 5, characterized in that to increase the open state of the gate valve Vehicle braking force control apparatus. Reservoir liquid amount detection means for detecting the amount of liquid flowing into the reservoir,
The gate valve control means, as the amount of liquid in the reservoir detected by the reservoir fluid amount detection means is large, any one of claims 2-6, characterized in that to reduce the open state of the gate valve The braking force control apparatus for vehicles described in 2. The said gate valve control means adjusts the open state of the said gate valve according to the liquid quantity ratio of the said reservoirs in these hydraulic brake systems, when there are a plurality of said hydraulic brake systems. The braking force control device for a vehicle according to 1 or 7 . A road surface friction coefficient detecting means for detecting a road surface friction coefficient;
The gate valve control means, as the friction coefficient of the road surface detected by the road surface friction coefficient detecting means is low, any one of claims 1,3～8, characterized in that to reduce the open state of the gate valve The braking force control apparatus for vehicles described in 2. A decrease speed detecting means for detecting a decrease speed of the road surface friction coefficient;
The gate valve control means, the faster the rate of decrease of the detected road surface friction coefficient by the reduced speed detecting means, any claim 1,2,4～9, characterized in that to reduce the open state of the gate valve The vehicle braking force control device according to claim 1. A brake operation amount detection means for detecting the brake operation amount;
The gate valve control means, the more the brake operation amount detected by the brake operation amount detecting means, any one of claims 1～3,5～10, characterized in that to reduce the open state of the gate valve The braking force control device for a vehicle according to the item. A pump having a suction side communicating between the reservoir and the outlet valve and a discharge side communicating between the master cylinder and the inlet valve;
The anti-skid control means is configured to increase, hold, and reduce the hydraulic pressure of the wheel cylinder by drivingly controlling the inlet valve, the outlet valve, and the pump. The vehicular braking force control device according to any one of 1 to 11 .

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