JP2015039953A - Vehicular brake apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a braking feeling of a vehicle including a combination between a disk brake and a drum brake.SOLUTION: A brake apparatus 2, for a vehicle that has disk brakes for left-right front wheels and drum brakes for left-right rear wheels 7FL,7FR,7RL,7RR, includes: retention valves 9FL,9FR,9RL,9RR respectively disposed in fluid supply paths of the individual brakes 7FL,7FR,7RL,7RR; a fluid pressure sensor 4 for detecting brake fluid pressure of a master cylinder 3; and an ABS control ECU 11 for open-close-controlling the individual retention valves 9FL,9FR,9RL,9RR. Further, the ABS control ECU 11 controls the retention valves 9FL,9FR on the disk brake-side in a closed state from when the master cylinder pressure reaches operation-start fluid pressure on the disk brake-side to when the pressure reaches operation-start fluid pressure on the drum brake-side, and then controls the retention valves 9FL,9FR to an open state from the closed state when the aforementioned pressure reaches operation-start fluid pressure on the drum brake-side.

Description

  The present invention relates to a vehicular braking device mounted on a vehicle in which front and rear wheel brakes are configured by a combination of a disc brake and a drum brake.

  In vehicles such as automobiles, hydraulic brakes are widely used. Among these hydraulic brakes, for example, there are disc type brakes and drum type brakes, and there are also vehicles that use them together. For example, Patent Document 1 discloses a vehicle braking device in which a front wheel side is constituted by a disc type brake and a rear wheel side is constituted by a drum type brake. In a general disc type brake, the brake fluid is supplied to the wheel cylinder, whereby the friction material of the pair of brake pads is pressed against the brake disc rotor, and the rotation of the wheel is suppressed. Further, in the drum type brake, the brake fluid is supplied to the wheel cylinder, whereby the lining (friction material) of the pair of brake shoes is pressed against the brake drum, and the rotation of the wheel is suppressed.

  The friction material that contributes to the braking of the disc type brake is, for example, that the friction coefficient of the friction material tends to decrease when the brake is at a low temperature close to the atmospheric temperature. Does not change much. Therefore, in a vehicular braking system in which the front wheels are constituted by disc type brakes and the rear wheels are constituted by drum type brakes, if the brake hydraulic pressure from the master cylinder is configured to give equal pressure to both brakes, When the temperature is low, the braking distribution between the front wheels and the rear wheels becomes closer to the rear wheels, which may cause the rear wheels to lock.

  Therefore, in the vehicle braking device described in Patent Document 1, the temperature of the disc-type brake on the front wheel side is detected, and the brake applied to the drum-type brake on the rear wheel side when the detected temperature is low compared to when it is high. Control fluid pressure low. In normal times when the brake temperature is not low, equal brake fluid pressure is applied to both the front and rear wheel brakes. Controlling the brake fluid pressure applied to both brakes in this way prevents the above-described rear wheel from being locked at low temperatures.

JP-A-62-299460 (see page 3, lower left column, line 12 to page 4, upper left column, line 3, line 3, etc.)

  By the way, disc brakes and drum brakes have different brake fluid pressures required for the brakes to start to work due to their structural differences. In general, drum brakes have higher brake fluid pressures. I need. Therefore, in the vehicular braking device described in Patent Document 1, when brake fluid pressure equal to both brakes is applied as in a normal time when the brake is not at a low temperature, the driver first depresses the brake pedal. The braking force by only the disc brakes on the front wheels is applied, and then the braking force by both brakes on the front and rear wheels is applied. In such a case, a moderate area and a steep area are formed in the rising of the braking force to the vehicle with respect to the depression amount of the brake pedal, and the brake feeling is deteriorated.

  The present invention has been made in view of the above problems, and is a vehicle braking device that can improve the brake feeling when the brakes of the front and rear wheels of the vehicle are configured by a combination of a disc brake and a drum brake. The purpose is to provide.

  In order to achieve the above-described object, the vehicle braking device of the present invention includes a brake device in which front wheels and rear wheels are configured by a combination of a disc brake and a drum brake, and the both brakes by depressing a brake pedal. The brake fluid pressure of the master cylinder includes: a master cylinder that applies brake fluid pressure to the vehicle; and a plurality of holding valves provided in each of brake fluid supply paths from the master cylinder to both brakes. And a control means for individually opening and closing the plurality of holding valves based on the brake fluid pressure detected by the detection means, wherein the control means is detected by the detection means. After the brake hydraulic pressure reaches the hydraulic start hydraulic pressure of one of the two brakes. The holding valve on the one brake side is controlled to be closed until reaching the brake operation start hydraulic pressure of the other brake, and is controlled to the closed state when the brake start hydraulic pressure of the other brake is reached. The holding valve is controlled to be in an open state (claim 1).

  According to the first aspect of the present invention, after the brake fluid pressure of the master cylinder detected by the detector reaches the action start fluid pressure of one of the disc-type and drum-type brakes, the control means. The holding valve on the one brake side is controlled to be closed until reaching the action start hydraulic pressure of the other brake. Then, when the brake fluid pressure of the master cylinder reaches the action start fluid pressure of the other brake, the holding valve of the one brake controlled in the closed state is controlled to be opened.

  In this case, while the brake fluid pressure of the master cylinder rises due to the depression of the brake pedal of the driver, the brake fluid pressure of the master cylinder is lower than the fluid pressure at which the brake starts to act among the disc type and drum type brakes. When the brake action starting hydraulic pressure is reached, the one brake side holding valve is closed. Therefore, even after that, even if the brake fluid pressure of the master cylinder rises to be higher than the operation start fluid pressure of one brake, the brake fluid pressure applied to one brake is held at the operation start fluid pressure (one side). . This holding state is maintained until the brake fluid pressure of the master cylinder reaches the action start fluid pressure of the other brake having a higher fluid pressure at which the brake begins to act. Then, when the operation start hydraulic pressure of the other brake is reached, the holding valve on one brake side in the closed state is opened, and the operation start hydraulic pressure on the other brake side is applied to both brakes.

  With this configuration, one brake side is given the action hydraulic pressure on one brake side until the brake hydraulic pressure of the master cylinder reaches the action start hydraulic pressure on the other brake side. Therefore, one of the brakes can be applied instantaneously when the holding valve controlled to be closed is opened. In addition, when the holding valve on one brake side is opened, the brake on the other side is given the hydraulic pressure at which the brake begins to act (action starting hydraulic pressure), so the brake on the other side also instantaneously Works. That is, when the brake fluid pressure of the master cylinder reaches the action start fluid pressure on the other brake side, all the brakes on the front and rear wheels start to work simultaneously, so the braking force on the vehicle changes linearly. Therefore, unlike the conventional vehicular braking device, there is no change in the rise of the braking force applied to the vehicle with respect to the depression amount of the brake pedal, so that the brake feeling can be improved.

1 is a block diagram of a vehicle braking device according to an embodiment of the present invention. It is operation | movement explanatory drawing of FIG. It is a flowchart for demonstrating the operation | movement of FIG.

  A vehicle braking device 2 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a block diagram of the vehicle braking device 2, FIG. 2 is an operation explanatory diagram of the vehicle braking device 2 of FIG. 1, and FIG. 2 (a) is a diagram of the vehicle 1 with respect to the depression amount (pedal stroke) of the brake pedal. (B) is the relationship of the brake fluid pressure applied to each brake 7FL, 7FR, 7RL, 7RR with respect to the pedal stroke, and (c) is the brake 7FL, 7FR (Fr of the left and right front wheels with respect to the pedal stroke). Brake) holding valves 9FL, 9FR are shown open / closed.

  A vehicle braking device 2 according to this embodiment is mounted on a vehicle 1 having an ABS (Antilock Bracket System) and applies a braking force to the vehicle 1. As shown in FIG. The hydraulic pressure sensor 4 for detecting the brake hydraulic pressure of the master cylinder 3 (corresponding to “detection means” of the present invention), the brake device 5 and the ABS actuator 6 used for ABS control are provided.

  The master cylinder 3 is connected to a brake pedal (not shown) via a brake booster (not shown). When the driver depresses the brake pedal, the master cylinder 3 is connected to each brake 7FL, 7FR, 7RL, 7RR of the brake device 5. Apply brake fluid pressure. A hydraulic pressure sensor 4 that detects the brake hydraulic pressure of the master cylinder 3 is attached to the main pipe 13 of the master cylinder 3.

  The brake device 5 includes four brakes 7FL, 7FR, 7RL, and 7RR provided to the left and right front wheels and the left and right rear wheels. In this embodiment, the brakes 7FL and 7FR for the left and right front wheels are both disc type brakes and the left and right rear wheels. Both the brakes 7RL and 7RR are constituted by drum brakes.

  The ABS actuator 6 controls the brake fluid pressure applied from the master cylinder 3 for each of the brakes 7FL, 7FR, 7RL, and 7RR, and each solenoid provided for each brake 7FL, 7FR, 7RL, and 7RR. The holding valve 9FL, 9FR, 9RL, 9RR and the pressure reducing valves 10FL, 10FR, 10RL, 10RR of the valve configuration, the holding valve 9FL, 9FR, 9RL, 9RR and the pressure reducing valves 10FL, 10FR, 10RL, 10RR are controlled to open and close. An ABS control ECU 11 having a computer configuration and a reservoir tank 12 are provided.

  Each holding valve 9FL, 9FR, 9RL, 9RR is for holding the brake fluid pressure applied to each wheel cylinder 8FL, 8FR, 8RL, 8RR, and each brake 7FL, 7FR, 7RL from the master cylinder 3 respectively. , 7RR is provided in the brake fluid supply path. Specifically, the main pipe 13 of the master cylinder 3 branches into four on the way to the brake device 5, and each of the four cylinder side branch pipes 14 FL, 14 FR, 14 RL, 14 RR branched from the main pipe 13 includes Are connected to the wheel cylinders 8FL, 8FR, 8RL, 8RR of the corresponding brakes 7FL, 7FR, 7RL, 7RR. And each holding valve 9FL, 9FR, 9RL, 9RR is provided in the corresponding cylinder side branch piping 14FL, 14FR, 14RL, 14RR, respectively. Each holding valve 9FL, 9FR, 9RL, 9RR is configured to open the brake fluid supply path in the non-excited state and close the brake fluid supply path in the excited state.

  In addition, each cylinder side branch pipe 14FL, 14FR, 14RL, 14RR also branches in the middle of the path connecting the holding cylinders 9FL, 9FR, 9RL, 9RR to the wheel cylinders 8FL, 8FR, 8RL, 8RR. Each of the four tank side branch pipes 15FL, 15FR, 15RL, 15RR branched from the branch pipes 14FL, 14FR, 14RL, 14RR is connected to the reservoir tank 12. These tank side branch pipes 15FL, 15FR, 15RL, 15RR are provided as brake fluid discharge paths for reducing the brake fluid pressure applied to the wheel cylinders 8FL, 8FR, 8RL, 8RR.

  The pressure reducing valves 10FL, 10FR, 10RL, and 10RR are for reducing the brake fluid pressure of the master cylinder 3 applied to the wheel cylinders 8FL, 8FR, 8RL, and 8RR, respectively. Provided in the side branch pipes 15FL, 15FR, 15RL, 15RR. The pressure reducing valves 10FL, 10FR, 10RL, and 10RR are configured to close the brake fluid discharge path in the non-excited state and open the brake fluid discharge path in the excited state.

  The reservoir tank 12 stores brake fluid discharged from the tank side branch pipes 15FL, 15FR, 15RL, and 15RR. The brake fluid stored in the reservoir tank 12 is pumped back to the master cylinder 3 side by a pipe 16 connected to the main pipe 13 of the master cylinder 3, thereby forming a brake fluid circulation mechanism.

  The ABS control ECU 11 operates the ABS by individually opening / closing the holding valves 9FL, 9FR, 9RL, 9RR and the pressure reducing valves 10FL, 10FR, 10RL, 10RR in order to prevent slipping of the wheels.

  Briefly explaining the operation of the ABS, the ABS control ECU 11 calculates the vehicle speed of the vehicle 1 by sequentially acquiring the speed of each wheel detected by a wheel speed sensor (not shown) provided on each wheel. Based on the calculated vehicle speed and the rotation speed of each wheel, the slip ratio is calculated for each wheel. Then, when the slip ratio of each wheel exceeds a predetermined value, such as when the driver suddenly brakes, it is determined that the wheel is locked. For example, when the ABS control ECU 11 determines that the left front wheel is locked, the holding valve 9FL of the brake 7FL that brakes the left front wheel is excited and controlled to be closed (brake fluid pressure is maintained), and the brake of the left front wheel is controlled. The 7FL pressure reducing valve 10FL is excited and controlled to open (reducing brake fluid pressure). By controlling in this way, the brake fluid pressure applied to the wheel cylinder 8FL of the brake 7FL of the left front wheel that has been locked is reduced, so that the braking force of the brake 8FL of the left front wheel is reduced and the lock is released. When the lock state is released and the slip ratio of the left front wheel becomes smaller than a predetermined value, the ABS control ECU 11 stops the excitation of the pressure reducing valve 10FL of the left front wheel that is controlled to the open state, and closes the control. Stop the excitation of the left front wheel holding valve 9FL to open it. As a result, the brake fluid pressure of the decompressed wheel cylinder 8FL is increased, and the brake 7FL of the left front wheel returns to the normal (without slip) braking force. As described above, the ABS control ECU 11 instantly controls the switching of the brake fluid pressure holding, pressure reduction and pressure increase, thereby preventing the wheels from being locked.

  As described above, in this embodiment, the left and right front wheel brakes 7FL and 7FR are both disc type brakes and the left and right rear wheel brakes 7RL and 7RR are both drum type brakes. In these disc type brakes and drum type brakes, the brake fluid pressure (brake action start fluid pressure) required for the brakes to start to operate may differ due to the difference in structure. The brake requires a higher brake action starting hydraulic pressure.

  Therefore, for example, when the driver depresses the brake pedal, if the brake fluid pressure from the master cylinder 3 is applied equally to each brake 7FL, 7FR, 7RL, 7RR, the driver depresses the brake pedal. In the process, first, the braking force by only the brakes 7FL and 7FR for the left and right front wheels acts on the vehicle 1, and then the braking force by all the brake brakes 7FL, 7FR, 7RL, and 7RR acts. Then, in the rising process of the braking force applied to the vehicle 1 with respect to the depression amount of the brake pedal of the driver, a region where the rising is gentle and a region where the rising is sharp are generated, resulting in poor brake feeling.

  Therefore, in this embodiment, the brake feeling can be improved by using the opening / closing control function of each holding valve 9FL, 9FR, 9RL, 9RR of the ABS control ECU 11 in the ABS actuator 6. .

The opening / closing control of each holding valve 9FL, 9FR, 9RL, 9RR of the ABS control ECU 11 will be specifically described with reference to FIG. 2. The ABS control ECU 11 detects a brake fluid pressure of the master cylinder 3. For example, when the driver depresses the brake pedal, the brake hydraulic pressure of the master cylinder 3 reaches the action start hydraulic pressure P1 of the brakes 7FL, 7FR of the left and right front wheels of the disk type configuration. when the (amount of depression _{S t1),} the left and right front wheel brake 7FL, 7FR side of the holding valve 9FL, by exciting the 9FR, controlled from an open state of the non-excited in the closed state (held in brake fluid pressure P1). At this time, the ABS control ECU 11 does not excite the holding valves 9RL and 9RR of the brakes 7RL and 7RR for the left and right rear wheels and keeps them open.

Further, the ABS control ECU 11 controls the closed state by further depressing the brake pedal of the driver, so that the brake hydraulic pressure of the master cylinder 3 is changed to the action start hydraulic pressure P2 of the left and right rear wheel brakes 7RL and 7RR. It is maintained until it reaches (depression amount: _{St 2} ).

Then, when the brake fluid pressure of the master cylinder 3 reaches the action start fluid pressure P2, the ABS control ECU 11 stops excitation of the left and right front wheel brakes 7FL, 7FR side holding valves 9FL, 9FR and closes them. The maintained holding valves 9FL and 9FR are controlled to be opened. Further, even if the depression amount is equal to or greater than _{S t2,} it maintains the holding valves 9FL, 9FR, 9RL, the control of the open state of 9RR. The ROM of the ABS control ECU 11 stores in advance information related to the action start hydraulic pressure P1 of the brakes 7FL and 7FR for the left and right front wheels and the action start hydraulic pressure P2 of the brakes 7RL and 7RR for the left and right front wheels in a disk configuration. These controls are performed based on this information and information from the hydraulic pressure sensor 4.

Then, as shown in FIG. 2 (b), when it reaches to the amount of depression _{S t2} of the brake pedal, the left and right front wheel brake 7FL, brake the brake fluid pressure applied to the 7FR is on the rear wheel side instantaneously 7RL, 7RR When the brake pedal is further depressed, the brake fluid pressure applied to all brakes is in an equal pressure state, and the brake fluid pressure is increased according to the depression amount. To rise. The opening / closing control functions of the holding valves 9FL, 9FR, 9RL, and 9RR by the ABS control ECU 11 correspond to the “control means” of the present invention.

As described above, the ABS control ECU 11 maintains the brake fluid pressure applied to the left and right front wheel brakes 7FL and 7FR at the operation start fluid pressure P1 during the depression amounts S _{t1 to} S _t2 , whereby the left and right rear wheel brakes are maintained. Until 7RL and 7RR start to work, it is possible to suppress the braking force from acting on the vehicle 1. Also, during this time, the left and right front wheel brake 7FL, the brake fluid pressure to 7FR is, because to be kept up to the working start hydraulic pressure P1, at the stage where the depression amount reaches the S _t2, all brake 7FL, 7FR, 7RL, and 7RR can be operated simultaneously. Therefore, as shown in FIG. 2 (a), when the driver depresses the brake pedal, the braking force rises against the vehicle 1 by the brakes 7FL, 7FR, 7RL, and 7RR becomes linear. Will improve.

  Next, the brake fluid pressure control process by the ABS control ECU 11 will be described with reference to FIG. FIG. 3 is a flowchart of the brake fluid pressure control process.

  First, in step S1, the ABS control ECU 11 determines whether or not the brake hydraulic pressure of the master cylinder 3 detected by the hydraulic pressure sensor 4 has reached the action start hydraulic pressure P1 of the brakes 7FL and 7FR for the left and right front wheels. If it is determined that it has reached, YES is passed through step S1, and the holding valves 9FL, 9FR on the left and right front wheel brakes 7FL, 7FR are excited and controlled to be closed (step S2). If the ABS control ECU 11 determines that the brake hydraulic pressure of the master cylinder has not reached the action start hydraulic pressure P1 of the brakes 7FL and 7FR for the left and right front wheels, the ABS control ECU 11 repeats the process of step S1 until it reaches.

  Next, the ABS control ECU 11 controls the brake fluid pressure of the master cylinder 3 to the left and right rear side by further pressing the brake pedal of the driver while the holding valves 9FL and 9FR on the left and right front wheels are controlled to be closed. It is determined whether or not the wheel brakes 7RL and 7RR reach the action start hydraulic pressure P2 (step S3). At this time, if the ABS control ECU 11 determines that the brake hydraulic pressure of the master cylinder 3 has reached the action start hydraulic pressure P2 of the brakes 7RL and 7RR of the left and right rear wheels, the step S3 is passed through YES, The excitation of the holding valves 9FL, 9FR on the brakes 7FL, 7FR side of the left and right front wheels is stopped, the holding valves 9FL, 9FR maintained in the closed state are controlled to be opened, and the process is terminated. When step S3 is NO, the ABS control ECU 11 repeats the process of step S3 until the brake hydraulic pressure of the master cylinder 3 reaches the action start hydraulic pressure P2 of the brakes 7RL and 7RR for the left and right rear wheels.

  Therefore, according to the above-described embodiment, in the process in which the brake fluid pressure of the master cylinder 3 increases due to the driver's depression of the brake pedal, the brake fluid pressure of the master cylinder 3 is lower than the fluid pressure at which the brake begins to act. When the starting brake hydraulic pressure P1 of the disc type brake (brakes 7FL and 7FR for the left and right front wheels) is reached, the ABS control ECU 11 controls the brake valves 9FL and 9FR on the left and right front wheels to be closed. Is done. Therefore, after that, even if the brake fluid pressure of the master cylinder 3 rises to the action start fluid pressure P1 or higher, the brake fluid pressure applied to the left and right front wheel brakes 7FL, 7FR is maintained at the action start fluid pressure P1. This holding state is maintained until the brake fluid pressure of the master cylinder 3 reaches the action start fluid pressure P2 of the drum brake (the left and right rear wheel brakes 7RL, 7RR) having the higher fluid pressure at which the brake starts to act. Is done. Then, when reaching the action start hydraulic pressure P2, the ABS control ECU 11 controls the left and right front wheel brakes 7FL, 7FR side holding valves 9FL, 9FR to be opened, and all brakes are closed. The action start hydraulic pressure P2 of the left and right rear wheel brakes 7RL, 7RR is applied to 7FL, 7FR, 7RL, 7RR.

  In this way, the brakes 7FL and 7FR for the left and right front wheels have the brake fluid pressure for the left and right front wheels until the brake fluid pressure of the master cylinder 3 reaches the action start fluid pressure P2 for the brakes 7RL and 7RR for the left and right rear wheels. , 7FR action starting fluid pressure P1 is held in the applied state, so that the left and right front wheel brakes 7FL, 7FR are instantaneously applied when the holding valves 9FL, 9FR controlled to the closed state are controlled to be opened. Can be made. Further, when the holding valves 9FL, 9FR on the left and right front wheel brakes 7FL, 7FR are controlled from the closed state to the open state, the hydraulic pressure at which the brakes start to act on the left and right rear wheel brakes 7RL, 7RR (operation start) Since the hydraulic pressure P2) is applied, the left and right rear wheel brakes 7RL and 7RR also act instantaneously. That is, when the brake fluid pressure of the master cylinder 3 reaches the action start fluid pressure P2 of the left and right rear wheel brakes 7RL and 7RR, all the brakes 7FL, 7FR, 7RL, and 7RR start to work simultaneously. The braking force for 1 changes linearly. Therefore, unlike the conventional vehicle braking device, there is no change in the rise of the braking force applied to the vehicle 1 with respect to the depression amount of the brake pedal, so that the brake feeling can be improved.

  Further, since the opening / closing control of each holding valve 9FL, 9FR, 9RL, 9RR can be performed by using an ABS actuator that is normally provided in the ABS, the vehicle braking device 2 that can improve the brake feeling. Can be provided at low cost.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit thereof. For example, in the above-described embodiment, the brake is The device 5 has been described with respect to the case where the left and right front wheel brakes 7FL and 7FR are disc type brakes and the left and right rear wheel brakes 7RL and 7RR are drum type brakes, but the brake device 5 includes disc type brakes and drum type brakes. Any combination may be used as long as the combination is configured.

  Further, the ABS actuator 6 may include a hydraulic pressure sensor 4 that detects the brake hydraulic pressure of the master cylinder 3.

DESCRIPTION OF SYMBOLS 1 ... Vehicle 2 ... Brake device for vehicles 3 ... Master cylinder 4 ... Hydraulic pressure sensor (detection means)
5 ... Brake device 7FL, 7FR ... Left and right front wheel brake (disc type brake)
7RL, 7RR ... Left and right rear wheel brake (drum brake)
9FL, 9FR, 9RL, 9RR ... Holding valve 11 ... ABS control ECU (control means)

Claims (1)

A brake device in which front wheels and rear wheels are constituted by a combination of a disc brake and a drum brake, a master cylinder that applies brake fluid pressure to both brakes by depressing a brake pedal, and both brakes from the master cylinder A braking device for a vehicle having a plurality of holding valves provided in each of the brake fluid supply paths toward
Detecting means for detecting the brake fluid pressure of the master cylinder;
Control means for individually opening and closing the plurality of holding valves based on the brake fluid pressure detected by the detection means;
From the time when the brake hydraulic pressure detected by the detection means reaches the action start hydraulic pressure of one of the two brakes to the action start hydraulic pressure of the other brake. During this time, the holding valve on the one brake side is controlled to be in a closed state, and the holding valve that has been controlled to be in the closed state is controlled to be opened when the operation start hydraulic pressure of the other brake is reached. A braking device for a vehicle characterized by the above.

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