JP2008179272A - Vehicle changing distribution of friction braking force between front and rear wheels based on temperature of friction engagement part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the load-resistant performance of a friction braking device by paying attention to the fact that, even if the temperature of a friction engagement part of the friction braking device of a vehicle such as an automobile is raised to a temperature of causing fade, only the friction engagement part having the highest temperature rise is firstly subjected to such a phenomenon when there is a temperature difference between the friction engagement parts of each wheel, and the friction engagement parts of other wheels are still affordable in the temperature rise. <P>SOLUTION: When the temperature of a friction engagement part of either a front wheel friction braking means or a rear wheel friction braking means exceeds the limit value, a part of the braking force of the front wheel side or rear wheel side friction braking means in which the temperature of the friction engagement part exceeds the limit value is shifted to the friction braking means on the longitudinally opposite side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle such as an automobile equipped with a friction braking device, and more particularly to dealing with a braking force reduction (fade) due to overheating of a friction engagement portion of the friction braking device.

In a friction braking device in a vehicle such as an automobile, the braking force decreases when the degree of overheating proceeds beyond a certain limit. This is called a fade. Patent Document 1 below discloses a brake pad according to the braking speed during braking so that the temperature of the brake pad in the friction braking device can be accurately estimated and optimal braking control can be performed without changing the braking force. A first temperature calculating means for calculating the temperature rise of the brake pad, and a second temperature calculating means for calculating the temperature rise of the brake pad according to the braking force and wheel speed during braking, and these two temperature calculating means Based on this, it is described that the temperature of the brake pad is estimated. On the other hand, in Patent Document 2 below, in a vehicle having a friction braking device and a regenerative braking device for each wheel, the temperature of the brake pad in the friction braking device for each wheel is estimated and estimated. Controlling the distribution between friction braking and regenerative braking based on the temperature of the brake pads is described. In Patent Document 3 below, the pedal force information detected by the pedal force detection sensor provided on the arm portion of the brake pedal and the friction force acting between the rotating portion and the non-rotating portion of the friction braking device are detected. It is described that a malfunction of a friction braking device such as a fade is determined from a comparison with the output of the second sensor, and the auxiliary braking device is activated when the friction braking device malfunctions. Further, in Patent Document 4 below, a decrease in the braking force generation efficiency of the braking force generation mechanism or its risk is determined based on the temperature of the friction material pressed against the brake rotor, or based on the operating state of the braking force generation mechanism. It is described that the temperature of the friction material is estimated.
JP 7-156780 A JP2005-14692 JP 2000-289593 A JP 2001-39280 A

  The distribution of the braking force between the front and rear wheels when braking a vehicle such as an automobile is generally determined to be optimal mainly from the viewpoint of ensuring the running stability of the vehicle during braking. However, since the manner of braking in the operation of the vehicle changes in various ways, the distribution of the braking force between the front and rear wheels from the viewpoint of ensuring running stability is not necessarily limited to the friction engagement portion and the rear wheel of the front wheel friction braking device during braking. The frictional engagement portion of the friction braking device does not cause the same temperature increase, and even in the case of a vehicle of the same design, the temperature increase of the frictional engagement portion of the front wheel friction braking device and the rear wheel friction braking device depending on the circumstances. It is conceivable that there is a considerable difference between the temperature increase of the friction engagement portion. The temperature difference between the friction engagement portion of the front wheel friction brake device and the friction engagement portion of the rear wheel friction brake device is a temperature range in which the temperatures of both of them do not cause a malfunction of the friction brake device such as a fade. If it is within, it will not be a problem.

  On the other hand, even if the temperature of the frictional engagement portion of the friction braking device may approach the temperature at which malfunction such as fading occurs, if there is a temperature difference between the frictional engagement portions of the friction braking device for each wheel First, such a state is only the frictional engagement portion of the friction braking device that has caused the largest temperature increase, and the frictional engagement portions of the other friction braking devices still have room for temperature increase. It will be.

  If the present invention is between the above-mentioned matters and the front wheel friction braking device including the left and right and the rear wheel friction braking device including the left and right, even if a part of the braking force is temporarily transferred between them, Focusing on the fact that it is not a problem from the viewpoint of ensuring running stability, it is an object to improve the load resistance performance of the friction braking device of the vehicle.

  In order to solve the above problems, the present invention includes a front wheel friction braking unit that brakes the front wheel and a rear wheel friction braking unit that brakes the rear wheel, and either the front wheel friction braking unit or the rear wheel friction braking unit is provided. When the temperature of one of the friction engagement parts exceeds a limit value determined therefor, one of the braking forces of the friction braking means on the front wheel side or the rear wheel side when the temperature of the friction engagement part exceeds the limit value. The present invention proposes a vehicle characterized in that the part is moved to the friction braking means on the opposite side in the front-rear direction.

  The limit value may be a lower limit value of a temperature range in which the braking force may be lowered when the temperature of the friction engagement portion of the friction braking means rises further.

  Once the braking force partial transfer is started, it is performed until the temperature of the friction engagement portion of the friction braking means is lowered to a predetermined transfer end temperature set to a value lower than the limit value. It's okay.

  During the execution of the partial transfer of the braking force between the front wheel friction braking means and the rear wheel friction braking means, the temperature of the friction engagement portion of the friction braking means on the side receiving the partial braking force transfer is determined. When the limit value is exceeded, it may be stopped.

  The front wheel and the rear wheel are respectively on the left and right, the front wheel friction braking means is provided separately for the left and right front wheels, and the rear wheel friction braking means is provided separately for the left and right rear wheels. Alternatively, when the temperature of the friction engagement portion of the friction braking means for either the right front wheel exceeds the limit value defined for it, the temperature of the friction engagement portion of the front wheel friction braking means is determined for the friction engagement portion. When it is determined that the limit value has been exceeded and the temperature of the frictional engagement portion of the friction braking means for either the left rear wheel or the right rear wheel exceeds the limit value determined therefor, the rear wheel friction braking means It may be determined that the temperature of the friction engagement portion exceeds the limit value defined for the friction engagement portion.

  The partial transfer of the braking force is either that the vehicle speed is equal to or higher than a predetermined value, or that the lateral acceleration acting on the vehicle or the value of the vehicle operation parameter equivalent thereto is equal to or lower than a predetermined value defined for it. Or it may be performed on condition of both.

  As described above, in the vehicle having the front wheel friction braking means for braking the front wheel and the rear wheel friction braking means for braking the rear wheel, either the front wheel friction braking means or the rear wheel friction braking means is frictionally engaged. When the temperature of the part exceeds the limit value set for it, a part of the braking force of the friction braking means on the front wheel side or the rear wheel side where the temperature of the friction engagement part exceeds the limit value is If it is to be transferred to the friction braking means, the temperature of the friction engagement portion of the friction braking means of either the left or right front wheel or the left or right rear wheel may cause malfunction of the friction braking means such as a fade first. Even if the temperature exceeds a certain temperature, if there is a temperature difference between the frictional engagement portions of the friction braking device for each wheel, there is still room for temperature increase in the frictional engagement portions of the friction braking means of the other wheels. Reached the limit temperature at that time Transfer a part of the braking force from the friction braking means to another friction braking means (that is, reduce the braking force of one friction braking means and increase the braking force of the other friction braking means correspondingly). Thus, the friction engagement portion of any friction braking means can be prevented from exceeding a predetermined limit temperature. In this case, if partial transfer of the braking force is performed between the front and rear wheels, with the left and right front wheels and the left and right rear wheels as a set, the overall braking force does not change and the braking force is controlled between the left and right wheels. Since the power is not transferred, the braking performance and running stability of the vehicle are not impaired.

  If the limit value is the lower limit value of the temperature range in which the braking force may be reduced if the temperature of the friction engagement portion of the friction braking means rises further, the friction engagement means will have its friction engagement. It is possible to avoid the occurrence of a state in which the braking force is reduced due to the temperature rise of the part.

  Once the partial transfer of the braking force is started, it is performed until the temperature of the friction engagement portion of the friction braking means is lowered to a predetermined transfer end temperature set to a value lower than the limit value. If so, by appropriately setting the transfer end temperature, an appropriate hysteresis can be given to the temperature limited control, and stable control can be performed.

  During the execution of the partial braking force transfer between the front wheel friction braking means and the rear wheel friction braking means, the temperature of the friction engagement portion of the friction braking means on the side receiving the partial braking force transfer is determined. If the limit value is exceeded, if the brake is to be stopped, the friction braking means on the side that receives a partial transfer of the braking force causes the friction engagement portion to rise in temperature exceeding the limit value as the braking force increases. Can be prevented.

  The front wheel and rear wheel of the vehicle have left and right, respectively, but the front wheel friction braking means is provided separately for the left and right front wheels, and the rear wheel friction braking means is provided separately for the left and right rear wheels. In this case, when the temperature of the frictional engagement part of the frictional braking means for either the left front wheel or the right front wheel exceeds the limit value defined therefor, the temperature of the frictional engagement part of the front wheel frictional braking means When it is judged that the limit value defined for the joint portion has been exceeded, and the temperature of the friction engagement portion of the friction braking means for either the left rear wheel or the right rear wheel has exceeded the limit value defined for it If it is determined that the temperature of the friction engagement portion of the rear wheel friction braking means has exceeded the limit value defined for the friction engagement portion, the left and right wheels of the front wheel and the rear wheel respectively When the temperature rise beyond the limit to the friction engagement of the friction brake means for displacement or the other occurs, it is possible to appropriately deal with any of the left and right wheels.

  If the braking force partial transfer described above is performed when the vehicle is traveling at a relatively low speed such as approximately 40 km / h or less, the braking feeling may be impaired. Accordingly, such a problem can be avoided if the braking force partial transfer is performed on condition that the vehicle speed is equal to or higher than a predetermined value. In addition, since the possibility of fading in the braking device is low during traveling at low speed, it is considered that the partial transfer of the braking force is not necessary.

  Similarly, if the braking force partial transfer is performed under the condition that the lateral acceleration acting on the vehicle or the value of the vehicle operation parameter equivalent thereto is equal to or less than a predetermined value determined therefor. When braking when the vehicle is turning at a vehicle speed higher than a certain speed, or when the vehicle is braked in a state where it is receiving a crosswind of a certain level or more even while traveling straight, the distance between the front and rear wheels When the braking force is transferred to the vehicle, it is possible to avoid a situation in which an unexpected yaw moment acts on the vehicle to cause running instability.

  FIG. 1 is a schematic view showing a configuration of a hydraulic circuit of a braking device which constitutes a main part of an embodiment of a vehicle according to the present invention.

  In the hydraulic circuit 10 shown in FIG. 1, reference numeral 12 denotes a brake pedal, and brake oil is pressure-fed from the master cylinder 14 in response to the driver's depression of the brake pedal. A dry stroke simulator 16 is provided between the brake pedal 12 and the master cylinder 14.

  The master cylinder 14 has a first master cylinder chamber 14A and a second master cylinder chamber 14B, and these master cylinder chambers have a brake hydraulic pressure supply conduit 18L for the left front wheel and a brake hydraulic pressure supply conduit for the right front wheel, respectively. One end of 18R is connected. Wheel cylinders 20FL and 20FR that apply braking force to the left front wheel and the right front wheel are connected to the other ends of the brake hydraulic pressure supply pipes 18L and 18R, respectively.

  In the middle of the brake hydraulic pressure supply pipes 18L and 18R, normally open type electromagnetic on-off valves 22L and 22R are provided, respectively. The master cylinder chamber 14A and the master cylinder chamber 14B are respectively connected to the left front wheel and the right front wheel wheel cylinders 20FL and 20FR. It is designed to control communication. In the illustrated hydraulic circuit, the left front wheel and the right front wheel are directly braked by depressing the brake pedal, and the wheel cylinders 20RL and 20RR for the left rear wheel and the right rear wheel use an oil pump, which will be described later, as a hydraulic power source. The hydraulic pressure is supplied through an automatic hydraulic control system. A wet stroke simulator 26 is connected to a brake hydraulic pressure supply conduit 18L between the master cylinder chamber 14A and the electromagnetic open / close valve 22L via a normally closed electromagnetic open / close valve 24.

  A reservoir 28 is connected to the master cylinder 14, one end of an oil supply conduit 30 is connected to the reservoir 28, and an oil pump 34 driven by an electric motor 32 is connected to the other end. An accumulator 38 for accumulating high hydraulic pressure is connected to the hydraulic supply conduit 36 connected to the discharge side of the oil pump 34. The reservoir 28, the oil pump 34, and the accumulator 38 constitute a hydraulic pressure source that supplies hydraulic pressure to the wheel cylinders 20FL, 20FR, 20RL, and 20RR under the control of a microcomputer as will be described later. Although not shown in the drawing, a conduit for connecting the hydraulic supply conduit 36 on the discharge side of the oil pump 34 and the oil supply conduit 30 on the suction side is provided, and the pressure in the accumulator 38 is provided in the middle of the conduit. There is provided a relief valve that opens when oil exceeds a reference value and returns oil from the discharge side of the oil pump 34 to the suction side.

  The hydraulic supply conduit 36 on the discharge side of the oil pump 34 is located downstream of the normally closed electromagnetic on / off valves 22L and 22R of the normally closed electromagnetic on / off valves 40FL and 40FR, the conduits 42FL and 42FR, and the brake hydraulic pressure supply conduits 18L and 18R. It is connected to the wheel cylinders 20FL, 20FR for the left front wheel and the right front wheel through the portion, and the wheel cylinders 20RL for the left rear wheel and the right rear wheel through the normally closed electromagnetic on-off valves 40RL, 40RR and the conduits 44RL, 44RR. It is connected to 20RR. On the other hand, the wheel cylinders 20FL, 20FR, 20RL, and 20RR are connected to the return conduit 48 through normally closed electromagnetic on-off valves 46FL, 46FR, 46RL, and 46RR, and are directed toward the suction side of the oil pump 34 and the reservoir 28. Oil can be drained.

  During the non-braking operation of the vehicle, the electromagnetic on / off valves 22L and 22R are open, and the electromagnetic on / off valves 40FL, 40FR, 40RL and 40RR and the electromagnetic on / off valves 46FL, 46FR, 46RL and 46RR are closed. When the brake pedal is depressed, the electromagnetic on / off valves 22L and 22R are closed, and the electromagnetic on / off valves 40FL, 40FR, 40RL, and 40RR and the electromagnetic on / off valves 46FL, 46FR, 46RL, and 46RR are opened / closed according to the degree of depression of the brake pedal. Is controlled by a microcomputer, which will be described later, and the hydraulic pressure in each of the wheel cylinders 20FL, 20FR, 20RL, 20RR is closed by the electromagnetic on-off valves 46FL, 46FR, 46RL, 46RR, and the electromagnetic on-off valves 40FL, 40FR, 40RL. , 40RR is increased when it is opened, and conversely, when the electromagnetic on-off valves 40FL, 40FR, 40RL, 40RR are closed and the electromagnetic on-off valves 46FL, 46FR, 46RL, 46RR are opened, the pressure decreases. In this control process, the distribution of braking force to each wheel is controlled. In addition, when the vehicle is equipped with an anti-lock braking system (ABS), a vehicle running stability control system (VSC), etc., the electromagnetic on-off valves 40FL, 40FR, 40RL, 40RR and 46FL, 46FR, 46RL, 46RR are further Opened and closed under the control of the microcomputer. However, all these matters are well known in the art.

  When each of the wheel cylinders 20FL, 20FR, 20RL, and 20RR is supplied with hydraulic pressure, the brake shoes 50FL, 50FR, 50RL, and 50RR lining the brake pads are pressed against the brake disks 52FL, 52FR, 52RL, and 52RR. , Brake the corresponding wheel. The hydraulic pressure (brake hydraulic pressure) in each of the wheel cylinders 20FL, 20FR, 20RL, 20RR is detected by hydraulic sensors 54FL, 54FR, 54RL, 54RR. In addition, as the hydraulic sensors, hydraulic sensors 56L and 56R that detect the hydraulic pressure pressurized in the master cylinder chambers 14A and 14B and a hydraulic sensor 58 that detects the discharge pressure of the oil pump 34 are provided. Although not shown in FIG. 1, the brake shoes 50FL, 50FR, 50RL, and 50RR incorporate a pad temperature sensor that detects the temperature of the pad portion. Reference numeral 60 denotes a stroke sensor that detects the depression stroke of the brake pedal.

  FIG. 2 is a block diagram showing a control device for the brake hydraulic circuit of FIG. The illustrated microcomputer 62 is provided not only for controlling the brake hydraulic circuit in FIG. 1 but also for various computer control of the vehicle including the ABS and VSC supplied with signals from various sensors. However, regarding the control of the brake hydraulic circuit in FIG. 1, in addition to the signals from the hydraulic sensors 54FL to 54RR, 56L, 56R, 58 and the stroke sensor 60, the vehicle speed sensor 64, the yaw rate sensor 66, Acceleration sensor 68. Signals indicating the respective information are supplied from the wheel speed sensors 70FL to 70RR and pad temperature sensors 72FL, 72FR, 72RL, 72RR, etc., which detect the temperature of the pad portions of the brake shoes 50FL to 50RR, and pass through the drive circuit 74. The on / off of the electric motor 32 and the opening / closing of the electromagnetic opening / closing valves 22L, 22R, 40FL to 40RR, 46FL to 46RR are controlled.

  FIG. 3 is a flowchart showing an example of a procedure for executing the braking control of the vehicle according to the present invention by operating the hydraulic circuit shown in FIG. 1 by the control device shown in FIG. The control according to the flowchart may be repeated at a cycle of several tens to several hundreds of milliseconds during operation of the vehicle.

  When the control is started, in step 10, brake pad temperatures Tbsi (i = fl, fr, rl, rr) on the left and right front wheels and the left and right rear wheels are detected. The temperature of the pad is most accurately measured directly by the above-described pad temperature sensors 72FL to 72RR, but may be estimated based on various parameters related to the operation of the braking device.

Next, the control proceeds to step 30, and it is determined whether or not the vehicle speed V is equal to or higher than a predetermined value Vm. This predetermined value Vm is a vehicle speed value for preventing the braking force front / rear distribution change control according to the present invention from being performed when the vehicle is traveling at a lower vehicle speed, for example, a value of about 40 km / h. May be. When the answer is no (N), the control proceeds directly to step 160, which will be described later, and normal braking control is executed without performing braking force front / rear distribution change control. If the vehicle speed does not exceed Vm and the answer is yes (Y), control proceeds to step 30.

  In step 30, it is determined whether the lateral acceleration acting on the vehicle body represented by the product of the vehicle speed V and the yaw rate γ of the vehicle body is equal to or greater than a predetermined value Gm. This predetermined value Gm is also a value of the lateral acceleration to prevent the braking force front / rear distribution change control according to the present invention from being performed in order to maintain the running stability of the vehicle in a state in which a lateral acceleration greater than this value is applied to the vehicle. Value. Instead of the product of the vehicle speed V and the yaw rate γ of the vehicle body, the detection value of the lateral acceleration sensor may be used. If the answer is yes, control proceeds directly to step 160 described below. If the answer is no, control proceeds to step 40.

  In step 40, the higher of the brake pad temperatures Tbsfl and Tbsfr at the left and right front wheels detected or estimated in step 10 is Tbsf, and the higher of Tbsrl and Tbsrr is Tbsr. An operation is performed. Control then proceeds to step 50.

  In step 50, it is determined whether or not the flag Sf is 1. The flag S1 is reset to 0 at the start of the control, and is set to 1 when the control reaches Step 180, which will be described later. Therefore, the answer is no until then, and the control proceeds to Step 60 during that time. .

  In step 60, Tsbf calculated in step 40, that is, whether the higher temperature of the brake pad on the left and right front wheels is equal to or higher than a predetermined limit value Tmf1 set for it. Is judged. This limit value Tmf1 is a lower limit value of a temperature range in which the braking force may be lowered when the temperature of the brake pads on the left and right front wheels rises further. If the answer is no, control proceeds to step 70. The case where the answer is yes will be described later.

  In step 70, it is determined whether or not the other one flag Sr is 1. This flag Sr is also reset to 0 at the start of the control, and is set to 1 when the control reaches Step 90 described later, so far the answer is no. Accordingly, control proceeds to step 80 first.

  In step 80, Tsbr calculated in step 40, that is, whether the higher temperature of the brake pads on the left and right rear wheels is equal to or higher than a predetermined limit value Tmr1 set for it. Is judged. This limit value Tmr1 is a lower limit value of a temperature region in which the braking force may be lowered when the temperature of the brake pads on the left and right rear wheels rises further. If the answer is no, that is, if there is no problem with the temperature increase of the brake pads in the front and rear wheels, the control proceeds to step 160 without performing the braking force front / rear distribution change control according to the present invention. Then, the braking control is executed as it is. However, if the temperature rise exceeding the limit value has occurred in the brake pad on either the left or right rear wheel, and the answer to step 80 is yes, control proceeds to step 90.

  In step 90, the flag Sr is set to 1. Thereafter, when the control reaches step 70, the control does not proceed to step 80, that is, the following control after step 100 is performed without checking again the temperature of the brake pad of the rear wheel.

  In step 100, whether or not the higher temperature of the brake pad at the left and right front wheels, which is the same as the determination in step 60, is not less than a predetermined limit value Tmf1 set for it. That judgment is made again. This is a result of the partial transfer of the braking force from the rear wheel friction braking means to the front wheel friction braking means by the steps after step 100 even if the temperature of the brake pads on the left and right front wheels is not initially high. This is to deal with the fact that the temperature of the brake pad at the front wheel may rise beyond the limit value. As long as the answer to step 100 is no, control proceeds to step 110. I will explain later when the answer is yes.

  In step 110, it is determined whether or not the brake pad temperature Tbsr in the rear wheel is equal to or higher than a predetermined value Tmr2. The predetermined value Tmr2 is a value set lower than the limit value Tmr1. When the braking force partial transfer control is once started, the brake pad temperature Tbsr at the rear wheel is thereby set to the limit value. Even if the value falls below Tmr1, the control is not immediately stopped, but a certain hysteresis is given to the control to ensure the stability of the control. Accordingly, once the control for transferring a part of the braking force from the rear wheel friction braking means to the front wheel friction braking means is started, the temperature Tbsr of the brake pad at the rear wheel decreases to Tmr2, that is, step 110. While the answer is yes, control proceeds to step 120. The case where the answer to step 110 is no will be described later.

  In step 120, a temperature reduction amount ΔTbsr to reduce the temperature of the rear wheel brake pad is calculated as a difference between Tbsr and Tmr2.

  Next, at step 130, the braking force reduction amount ΔFr to reduce the braking force of the friction braking means for the rear wheel in order to lower the temperature of the rear wheel brake pad by ΔTbsr is not only ΔTbsr in this example, but also at that time. It is calculated as the value of the function βfr (Fr, V, Ta, ΔTbsr) having the rear wheel braking force Fr, the vehicle speed V, and the outside air temperature Ta as variables. Such a function value may be prepared as an appropriate map for each variable and obtained by referring to it.

  Next, at step 140, the value of the hydraulic pressure reduction amount ΔPr to which the rear wheel braking hydraulic pressure should be reduced in order to reduce the braking force at the rear wheel by ΔFr is set as the value of the function βpr (ΔFr) having ΔFr as a variable. Calculated. This may also be prepared as an appropriate map for ΔFr and determined by referring to it.

  In step 150, the value of the hydraulic pressure increase amount ΔPf to which the front wheel braking hydraulic pressure should be increased in order to increase the braking force at the front wheel by the amount of the braking force reduction amount ΔFr at the rear wheel is changed to ΔFr. Is calculated as the value of the function βpf (ΔFr). This may also be prepared as an appropriate map for ΔFr and determined by referring to it.

  After changing the braking force distribution between the front and rear wheels as described above, braking control is executed in step 160.

  In the transfer control of a part of the braking force from the rear wheel side to the front wheel side, unless the brake pad temperature Tbsf of the front wheel increases beyond the limit value Tmf1, the brake pad temperature Tbsr of the rear wheel is equal to Tmr2. Continue until it falls. When the braking load on the rear wheel is reduced by transferring a part of the braking force from the rear wheel side to the front wheel side, and the temperature Tbsr of the brake pad on the rear wheel is lowered to Tmr2, the answer to step 110 is Since yes to no, control proceeds to step 170 at that time. Here, the rear wheel braking hydraulic pressure reduction amount ΔPr and the front wheel braking hydraulic pressure increase amount ΔPf are both reset to 0, and the flag Sr indicating that the partial braking force transfer control from the rear wheel side to the front wheel side is being executed. Reset to zero.

  In addition, during the partial braking force transfer control from the rear wheel side to the front wheel side, if a situation occurs in which the brake pad temperature Tbsf of the front wheel rises above Tmf1, this means that the answer to step 100 is no to yes. It is detected by turning to. When such a situation occurs, the power partial transfer control is stopped at that time.

  When the brake pad temperature of the front wheel exceeds the limit value, the answer to step 60 is yes, and then the control proceeds to step 180 and the flag Sf is set to 1. Thereafter, control proceeds from step 50 to step 180 without proceeding from step 50 to step 60.

  Next, at step 190, it is checked whether the temperature Tbsr of the brake pad at the rear wheel has exceeded its limit value Tmr1. This is a check to prevent the brake pad temperature of the rear wheel from exceeding the limit value due to a partial transfer of the braking force from the front wheel side to the rear wheel side, as described for step 100. When the temperature of the brake pad and the temperature of the rear wheel brake pad simultaneously exceed the respective limit values, that is, when the flag Sf is still 0, the control proceeds to step 60, where the answer is yes for the first time. Is the first time to proceed to step 190, it is also checked when the answer to step 190 is yes, in other words, when the brake pad temperature exceeds the limit value at the same time on the front and rear wheels. This indicates that the braking force is not transferred between the front and rear wheels.

  The control from step 190 to step 250 is performed in the same manner as the control described in partly transferring the braking force from the rear wheel side to the front wheel side from step 100 to step 170, and from the front wheel side to the rear wheel side. A part of the braking force is transferred to In the illustrated flowchart, f and r in suffixes attached to the letters T, F, and P representing temperature, braking force, and hydraulic pressure indicate that they relate to the front wheel and the rear wheel, respectively. From the description of the braking force partial transfer control from the rear wheel side to the front wheel side in the above steps 100 to 170, the point of the braking force partial transfer control from the front wheel side to the rear wheel side in steps 190 to 250 is clear. Therefore, a redundant description thereof will be omitted to avoid redundancy of the specification.

  While the present invention has been described in detail with respect to one embodiment thereof, it will be apparent to those skilled in the art that various modifications can be made within the scope of the present invention.

Schematic which shows an example of a structure of the hydraulic circuit of the braking device in the vehicle by this invention. The block diagram which shows the control apparatus with respect to the brake hydraulic circuit of FIG. The flowchart which shows an example of the braking force partial transfer control between the front and rear wheels performed in the vehicle according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Hydraulic circuit, 12 ... Brake pedal, 14 ... Master cylinder, 14A, 14B ... Master cylinder chamber, 16 ... Dry stroke simulator, 18L, 18R ... Brake hydraulic pressure supply conduit, 20FL-20RR ... Wheel cylinder, 22L, 22R ... Always Open solenoid open / close valve, 24 ... Normally closed solenoid open / close valve, 26 ... wet stroke simulator, 28 ... reservoir, 30 ... oil supply conduit, 32 ... electric motor, 34 ... oil pump, 36 ... hydraulic supply conduit, 38 ... accumulator, 40FL to 40RR: Normally closed solenoid valve, 42FL, 42 ... Conduit, 44RL, 44RR ... Conduit, 46FL-46RR ... Normally closed solenoid valve, 48 ... Return conduit, 50FL-50RR ... Brake shoe, 52FL-52RR ... Brake disc, 54FL-54RR ... Hydraulic sensor, 56L, 6R ... hydraulic sensor, 58 ... hydraulic sensor, 60 ... stroke sensor, 62 ... microcomputer, 64 ... vehicle speed sensor, 66 ... yaw rate sensor, 68 ... lateral acceleration sensor, 70FL-70RR ... wheel speed sensor, 72FL-72RR ... brake pad Temperature sensor, 74 ... drive circuit

Claims (7)

  It has a front wheel friction braking means for braking the front wheel and a rear wheel friction braking means for braking the rear wheel, and the temperature of the friction engagement portion of either the front wheel friction braking means or the rear wheel friction braking means is determined therefor. When the specified limit value is exceeded, a part of the braking force of the friction braking means on the front wheel side or the rear wheel side where the temperature of the friction engagement portion exceeds the limit value is transferred to the friction braking means on the opposite side in the front-rear direction. A vehicle characterized by   The vehicle according to claim 1, wherein the limit value is a lower limit value of a temperature range in which a braking force may be reduced when the temperature of the friction engagement portion of the friction braking unit is further increased.   Once the braking force partial transfer is started, it is performed until the temperature of the friction engagement portion of the friction braking means decreases to a predetermined transfer end temperature set to a value lower than the limit value. The vehicle according to claim 1, wherein the vehicle is a vehicle.   During the execution of the partial transfer of the braking force between the front wheel friction braking means and the rear wheel friction braking means, the temperature of the friction engagement portion of the friction braking means on the side receiving the partial braking force transfer is determined. The vehicle according to any one of claims 1 to 3, wherein the vehicle is stopped when the limit value is exceeded.   The front wheel and the rear wheel are respectively on the left and right, the front wheel friction braking means is provided separately for the left and right front wheels, and the rear wheel friction braking means is provided separately for the left and right rear wheels. Alternatively, when the temperature of the friction engagement portion of the friction braking means for either the right front wheel exceeds the limit value defined for it, the temperature of the friction engagement portion of the front wheel friction braking means is determined for the friction engagement portion. When it is determined that the limit value has been exceeded and the temperature of the frictional engagement portion of the friction braking means for either the left rear wheel or the right rear wheel exceeds the limit value determined therefor, the rear wheel friction braking means 5. The vehicle according to claim 1, wherein the temperature of the friction engagement portion is determined to have exceeded the limit value defined for the friction engagement portion.   The vehicle according to any one of claims 1 to 5, wherein the partial transfer of the braking force is performed on condition that the vehicle speed is equal to or higher than a predetermined value.   The partial transfer of the braking force is performed on condition that the lateral acceleration acting on the vehicle or the value of the vehicle operation parameter equivalent thereto is equal to or less than a predetermined value determined therefor. The vehicle according to any one of claims 1 to 6.

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