JP2006193075A - Controller for stopping behavior of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce discomfort that an occupant feels when a vehicle is braked and stopped by controlling a braking force to reduce a rapid change in forward-rearward acceleration of the vehicle at braking and stopping of a vehicle. <P>SOLUTION: A target deceleration Gt of the vehicle is calculated on the basis of brake operating amount of a driver (S20). When it is determined that the vehicle is in a braked and stopped condition (S40, 50), a gain Kg for reducing the target deceleration is calculated so as to be decreased with a decrease in a ratio V/Gbx of a vehicle speed V to the deceleration Gbx of the vehicle (S80), a ratio of a rear wheel distribution Krs of the braking force is calculated to be decreased with a decrease in the ratio V/Gbx of the vehicle speed V to the deceleration Gbx of the vehicle (S90), the target deceleration Gta of the vehicle after correction is calculated as a product of the gain Kg for reducing the deceleration and the target deceleration Gt of the vehicle (S100), and the braking force of each wheel is controlled so that the target deceleration Gta of the vehicle after correction may be attained by the ratio of the rear distribution Krs of the braking force (S110, 120). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and more particularly to a stop behavior control device that reduces changes in behavior when the vehicle is stopped.

  As one of braking control devices for vehicles such as automobiles, as described in, for example, Patent Document 1 below, the rear wheel is set immediately before the vehicle stops in order to reduce vehicle body swingback when the vehicle is stopped. 2. Description of the Related Art Conventionally, a braking control device configured to increase the braking force distribution is known.

According to the braking control apparatus as described above, the braking force distribution of the rear wheels is increased immediately before the vehicle stops, thereby ensuring the stability of the vehicle at the time of braking and the vehicle body at the time of braking stop of the vehicle. Can be reduced (changes in the pitch angle of the vehicle body and the amount of pitch displacement).
JP 2001-18777 A

  However, according to the results of an experimental study conducted by the inventor of the present application, the discomfort felt by the occupant when the vehicle is stopped is not a change in the pitch angle of the vehicle body, but a shock caused by a sudden change (jerk) in the longitudinal acceleration of the vehicle. Therefore, even if the braking force distribution of the rear wheels is increased just before the vehicle stops to reduce the change in the pitch angle of the vehicle body and the amount of pitch displacement, the uncomfortable feeling that the passenger feels as a shock when the vehicle stops braking is effective. It was found that it cannot be reduced.

  The present invention has been made in view of the above-described problems in the conventional braking control device configured to increase the braking force distribution of the rear wheels immediately before the vehicle stops. Is based on the knowledge obtained as a result of the experimental research conducted by the inventor of the present application, by controlling the braking force so as to reduce the sudden change in the longitudinal acceleration of the vehicle when the vehicle is stopped. It is to effectively reduce the discomfort felt by the occupant when stopping.

  According to the present invention, the main problems described above are the configuration of claim 1, that is, the means for determining when the vehicle is stopped, and the front-rear compliance of the vehicle is greater than the value before stopping when the vehicle is stopped. This is achieved by a vehicle stop behavior control device having control means for controlling the longitudinal compliance of the vehicle.

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the control means substantially applies the braking force when the vehicle is stopped to the front or rear wheels. It is comprised so that the front-back compliance of a vehicle may be increased by allocating only to a wheel (structure of Claim 2).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1 or 2, the control means reduces the wheel support rigidity in the vehicle front-rear direction when the vehicle stops braking. To increase the longitudinal compliance of the vehicle.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of the first to third aspects, the vehicle has braking force control means for controlling the braking force of the wheels, The braking force control means is configured to control the braking force of the wheel so that the deceleration of the vehicle becomes smaller than the deceleration required for the vehicle when the vehicle is stopped.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claims 1 to 3, the vehicle deceleration decreases as the ratio of the vehicle speed to the vehicle deceleration decreases. It is comprised so that the braking force of a wheel may be controlled (structure of Claim 5).

  According to the present invention, in order to effectively achieve the above-mentioned main problems, in the configuration of claim 2, the vehicle has driving wheels and non-driving wheels, and the control means controls the braking of the vehicle. When the braking force at the time of stopping is substantially distributed only to the non-driving wheels, the braking force for reducing the creep torque is applied to the driving wheels.

  According to the present invention, in order to effectively achieve the above main problems, the means for determining when the vehicle is stopped is applied with a braking force on the wheel. When the vehicle speed is equal to or lower than the reference value in the situation, the vehicle is determined to be in a braking stop state (configuration of claim 7).

  The term “distributing braking force substantially only to the front wheels or rear wheels” in claim 2 is not limited to the case where the braking force on the side where the braking force is not distributed is 0, but when the braking of the vehicle is stopped. This includes the application of a braking force that allows free rotation of the wheel.

  According to the first aspect of the present invention, the vehicle front / rear compliance is controlled so that the vehicle front / rear compliance increases to a value before the brake stop when the vehicle is stopped. By reducing the natural frequency and reducing the elastic force of the rolling action acting on the vehicle body, it is possible to reliably reduce a sudden change in the longitudinal acceleration of the vehicle body and a shock in the vehicle acceleration direction resulting therefrom.

  According to the second aspect of the present invention, the front-rear compliance of the vehicle is increased by allocating the braking force when the vehicle is stopped to the front wheels or the rear wheels substantially, so the front-rear compliance of the vehicle is increased or decreased. No special device is required for this purpose, and the front-rear compliance of the vehicle can be easily and reliably increased when braking of the vehicle is stopped.

  According to the third aspect of the present invention, the front / rear compliance of the vehicle is increased by reducing the wheel support rigidity in the vehicle front-rear direction when the vehicle is stopped. It is possible to reliably increase the front-rear compliance of the vehicle while controlling the vehicle.

  According to the fourth aspect of the present invention, the braking force of the wheel is controlled so that the deceleration of the vehicle is smaller than the deceleration required for the vehicle when the vehicle is stopped. This is because the deceleration of the vehicle is surely reduced when the braking of the vehicle is stopped without requiring the operation of lowering the braking force of the wheel, thereby causing an excessive inertia force to act on the front of the vehicle on the occupant. A shock in the vehicle deceleration direction can be reliably reduced.

  In general, in order to reduce the shock when the vehicle is stopped, it is preferable that the vehicle deceleration decreases as the vehicle speed decreases. When the vehicle deceleration is high when the vehicle stops, the vehicle deceleration decreases. It is preferable that the degree of deceleration reduction of the vehicle decreases as the vehicle speed decreases sufficiently and the vehicle deceleration decreases.

  According to the fifth aspect of the present invention, since the braking force of the wheels is controlled so that the deceleration of the vehicle becomes smaller as the ratio of the vehicle speed to the deceleration of the vehicle becomes smaller, the deceleration of the vehicle becomes smaller as the vehicle speed becomes lower. In addition, it is possible to sufficiently reduce the vehicle deceleration when the vehicle deceleration is high when the vehicle is stopped, and to reduce the vehicle deceleration decrease as the vehicle deceleration decreases.

  According to the sixth aspect of the present invention, when the braking force when the vehicle is stopped is substantially distributed only to the non-driving wheels, the braking force for reducing the creep torque is applied to the driving wheels. Even when the braking force is substantially distributed only to the non-driving wheels when the braking is stopped, it is possible to reliably suppress an increase in the braking distance of the vehicle due to the creep torque of the driving wheels. Particularly when the front wheel is a driven wheel and the rear wheel is a driving wheel, the braking force for stopping braking is applied to the front wheel and the braking force for reducing creep torque is applied to the front wheel. Can be applied to avoid the situation where the driving force is generated by the rear wheels when the braking force is applied to the front wheels, thereby improving the running stability of the vehicle when braking is stopped. Can be made.

  According to the seventh aspect of the present invention, when the braking speed is applied to the wheels, it is determined that the vehicle is stopped when the vehicle speed is equal to or lower than the reference value. In other words, it is possible to reliably determine the situation in which the braking force is applied to the wheels and the vehicle speed is reduced to stop the vehicle.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration according to any one of claims 1 to 7, the control means controls the longitudinal compliance of the vehicle according to at least the vehicle speed so that the longitudinal compliance of the vehicle increases as the vehicle speed decreases. (Preferred embodiment 1).

  According to another preferred aspect of the present invention, in the configuration according to any one of the first to seventh aspects of the present invention, the control means is configured such that the front-rear compliance of the vehicle increases as the ratio of the vehicle speed to the vehicle deceleration decreases. The vehicle front-rear compliance is controlled according to the ratio of the vehicle speed to the deceleration (preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of claim 3, the control means is configured to reduce the rigidity in the vehicle longitudinal direction by reducing the rigidity of the end portion of the link of the suspension. (Preferred embodiment 3)

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 3 described above, the control means reduces the spring constant of the elastic bush incorporated in the end portion of the suspension link, thereby reducing the longitudinal direction of the vehicle. It is comprised so that rigidity may be reduced (Preferable aspect 4).

  According to another preferred aspect of the present invention, in the structure of claim 4 above, the deceleration required for the vehicle is determined based on the braking operation amount of the occupant (Preferred aspect 5). .

  According to another preferred aspect of the present invention, in the configuration of claim 4, the vehicle has an automatic braking device, and the deceleration required for the vehicle is determined based on the braking operation amount of the occupant. It is comprised so that it may obtain | require as a larger value among the deceleration and the target deceleration of an automatic braking device (Preferable aspect 6).

  According to another preferred aspect of the present invention, in the configuration of claim 7, the means for determining when the vehicle is stopped is such that the deceleration required for the vehicle is equal to or greater than a reference value and the vehicle speed is When the vehicle is below the reference value, the vehicle is determined to be in a braking stop state (preferred aspect 7).

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of a vehicle stop behavior control device according to the present invention applied to a vehicle capable of controlling the front-rear distribution of braking force.

  In FIG. 1, 10FL and 10FR respectively indicate the left and right front wheels of the vehicle 12, and 10RL and 10RR respectively indicate the left and right rear wheels that are drive wheels of the vehicle. The left and right front wheels 10FL and 10FR, which are both driven wheels and steering wheels, are driven via tie rods 18L and 18R by a rack and pinion type power steering device 16 driven in response to steering of the steering wheel 14 by the driver. Steered.

  The braking force of each wheel is controlled by controlling the braking pressure of the wheel cylinders 24FR, 24FL, 24RR, 24RL by the hydraulic circuit 22 of the braking device 20. Although not shown in the drawing, the hydraulic circuit 22 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven according to the depression operation of the brake pedal 26 by the driver. It is controlled by the master cylinder 28, and if necessary, it is controlled by the electronic control unit 30 as will be described in detail later.

  The master cylinder 28 is provided with a pressure sensor 34 for detecting the master cylinder pressure Pm, the brake pedal 26 is provided with a stroke sensor 36 for detecting the depression stroke St of the brake pedal, and the wheel cylinders 24FR to 24RL are provided with corresponding wheels. Pressure sensors 38FL to 38RR for detecting the pressure in the cylinder as the braking pressure Pi are provided. Signals indicating the master cylinder pressure Pm, the depression stroke St, and the braking pressure Pi (i = fl, fr, rl, rr) detected by these sensors are input to the electronic control unit 30.

  The electronic control unit 30 also receives a signal indicating the vehicle speed V detected by the vehicle speed sensor 40 and a signal indicating the vehicle lateral acceleration Gy detected by the lateral acceleration sensor 42. Although not shown in detail in FIG. 1, the electronic control device 30 has a general configuration in which, for example, a CPU, a ROM, a RAM, and an input / output port device are connected to each other via a bidirectional common bus. Includes a microcomputer.

  The electronic control unit 30 calculates the target deceleration Gt of the vehicle based on the driver's braking operation amount according to the flowchart shown in FIG. In addition, the electronic control unit 30 determines when the vehicle is stopped. When the vehicle stops, the electronic control unit 30 reduces the vehicle in such a manner that the ratio V / Gbx becomes smaller in the region where the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx is small. The target deceleration Gt of the vehicle is reduced and the rear wheel distribution ratio of the braking force is set to 0 in the region where the ratio V / Gbx is small, so that the target deceleration Gta of the vehicle after the reduction correction becomes the braking force of the front wheel. The braking force of each wheel is controlled so as to be achieved by only.

  The electronic control unit 30 sets the rear wheel distribution ratio of the braking force to the normal rear wheel distribution ratio without reducing and correcting the target deceleration Gt of the vehicle in the braking situation before the braking is stopped. Thus, the braking force of each wheel is controlled so that the target deceleration Gt of the vehicle is achieved by the rear wheel distribution ratio at the normal time by the braking force of the front and rear wheels.

  Next, the vehicle stop behavior control by the braking force control in the illustrated embodiment 1 will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

  First, in step 10, a signal indicating the master cylinder pressure Pm detected by the pressure sensor 36 is read, and in step 20, based on the amount of braking operation of the driver according to the flowchart shown in FIG. A target deceleration Gt of the vehicle as a driver's required braking amount is calculated.

  In step 40, it is determined whether or not the target deceleration Gt of the vehicle is larger than a reference value Gto (a positive constant close to 0) for determining when the vehicle is stopped. If a negative determination is made, the process proceeds to step 60. If an affirmative determination is made, the process proceeds to step 50.

  In step 50, it is determined whether or not the vehicle speed V is smaller than a reference value Vo (a positive constant close to 0) for determining when the vehicle is stopped, that is, whether or not it is immediately before the vehicle stops. When an affirmative determination is made, the process proceeds to step 80. When a negative determination is made, the process proceeds to step 60.

In step 60, the rear wheel distribution ratio Krn during normal braking is calculated in a manner known in the art, and in step 70, a coefficient for converting deceleration to braking pressure is calculated as Kb. As described below, the target braking pressure Pbtf for the left and right front wheels and the target braking pressure Pbtr for the left and right rear wheels are calculated according to the following equations 1 and 2.
Pbtf = KbGt (1-Krn) (1)
Pbtr = KbGtKrn (2)

  In step 80, the target deceleration reduction gain Kg is calculated from the map corresponding to the graph shown in FIG. 4 based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx (= -Gx). At 90, the rear wheel distribution ratio Krs of the braking force is calculated from the map corresponding to the graph shown in FIG. 5 based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx.

In step 100, the target deceleration Gt of the vehicle is corrected by the deceleration reduction gain Kg according to the following equation 3, so that the corrected target deceleration Gta of the vehicle is calculated.
Gta = KgGt (3)

In step 110, the target braking pressure Pbtf for the left and right front wheels and the target braking pressure Pbtr for the left and right rear wheels are calculated according to the following equations 4 and 5.
Pbtf = KbGta (1-Krs) (4)
Pbtr = KbGtaKrs (5)

  In step 120, the braking pressure of each wheel is controlled so that the braking pressures Pfl and Pfr for the front wheels and the braking pressures Prl and Prr for the rear wheels become the target braking pressures Pbtf and Pbtr, respectively.

  Thus, according to the first embodiment shown in the figure, the target deceleration Gt of the vehicle as the driver's required braking amount is calculated based on the driver's braking operation amount in step 20, and in steps 40 and 50, the vehicle's target deceleration Gt is calculated. It is determined whether or not the brake is stopped. When the brake is stopped but not immediately before the stop, in steps 60, 70 and 120, the vehicle deceleration is controlled so as to become the target deceleration Gt. The braking force of the front and rear wheels is controlled by the power front / rear distribution ratio.

  On the other hand, if it is determined in steps 40 and 50 that the vehicle is in a braking stop state, the target deceleration reduction gain Kg is determined in step 80 based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx. In step 90, the rear wheel distribution ratio Krs of the braking force is calculated based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx. In step 100, the corrected vehicle target deceleration Gta is calculated. Is calculated as the product of the deceleration reduction gain Kg and the vehicle target deceleration Gt.

  In step 110, the target braking pressure Pbtf for the left and right front wheels and the target braking pressure Pbtr for the left and right rear wheels for achieving the corrected vehicle target deceleration Gta with the rear wheel distribution ratio Krs of the braking force are calculated. In step 120, the front wheel braking pressures Pfl and Pfr and the rear wheel braking pressures Prl and Prr are controlled to be the target braking pressures Pbtf and Pbtr, respectively.

  In this case, the rear wheel distribution ratio Krs of the braking force becomes smaller as the ratio V / Gbx of the vehicle speed V to the deceleration Gbx of the vehicle becomes smaller, and is calculated as 0 when the ratio V / Gbx is 0 or a value close to 0. Therefore, the corrected target deceleration Gta of the vehicle is achieved by applying the braking force only to the left and right front wheels when the braking of the vehicle is stopped.

  Therefore, according to the illustrated first embodiment, when the vehicle is stopped, the natural frequency in the front-rear direction of the vehicle is reduced and the front-rear compliance of the vehicle is increased compared to the case where braking force is applied to the front and rear wheels. This can reduce the force of the vehicle body in the direction of rolling back, reduce the degree of change in the longitudinal acceleration of the vehicle, and shock to the vehicle acceleration side felt by the occupant (the occupant is moved rearward relative to the vehicle body) Shock) can be reliably reduced.

  In particular, according to Example 1 shown in the figure, when the vehicle is stopped, the corrected target deceleration Gta of the vehicle is calculated so that the smaller the ratio V / Gbx of the vehicle speed V to the deceleration Gbx of the vehicle is, the smaller the corrected vehicle target deceleration Gbx is. Since the braking force of each wheel is controlled so that the target deceleration Gta of the vehicle is achieved, the inertial force forward of the vehicle when the vehicle is stopped can be gradually reduced, which is controlled by the vehicle occupant. Even if the power reduction operation is not performed, the shock to the vehicle deceleration side (shock that the occupant moves to the front of the vehicle relative to the vehicle body) can be reliably reduced. The shock to the vehicle acceleration side felt by the occupant can be further reliably reduced.

  Further, according to the illustrated embodiment 1, when the braking of the vehicle is stopped, the braking force is applied only to the left and right front wheels by setting the rear wheel distribution ratio Krs of the braking force to 0, so that the braking force is applied only to the left and right rear wheels. It is possible to reliably prevent the deterioration of the running stability of the vehicle due to the decrease in the lateral force of the rear wheels, as compared with the case where is provided.

  In the illustrated embodiment 1, the braking force is applied only to the left and right front wheels when the braking of the vehicle is stopped, but it may be modified so that the braking force is applied only to the left and right rear wheels. . In this case, it is possible to reduce the pitch angle and the pitch displacement amount of the vehicle when the vehicle is stopped when compared with the case of the illustrated embodiment 1.

  FIG. 9 is a schematic diagram showing a second embodiment of the vehicle stop behavior control device according to the present invention applied to a vehicle equipped with a front and rear wheel support rigidity varying device. 9, the same members as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

  In the second embodiment, as shown in FIG. 11, a rubber bushing device 102 is provided at the vehicle body side end portion of the suspension link 100. The rubber bushing device 102 has an inner cylinder 104 and an outer cylinder that are concentric with each other. It consists of a cylinder 106 and a rubber bush 108 mounted between them. The rubber bush 108 is provided with a pair of cavities 114 and 116 extending in an arc around the axis 112 of the rubber bush device 102 at positions on both sides of the inner cylinder 104 along the axis 110 of the suspension link 100. .

  Elastic variable members 118 and 120 are interposed in the cavities 114 and 116, respectively. The elastic variable members 118 and 120 have electrodes 118A, 118B and 120A, 120B at positions on both sides along the axis 110, respectively, and when a voltage is applied to these electrodes, the spring constant gradually decreases as the voltage increases. Elastic members 118C and 120C are interposed between corresponding electrodes. The applied voltage to the electrodes of the elastic variable members 118 and 120 is controlled by the electronic control unit 30 via the power supply circuit 44, whereby the longitudinal support rigidity of each wheel is variably set, and the longitudinal compliance of the vehicle is increased or decreased. ing.

  The elastic members 118C and 120C may be made of a material that reduces the spring constant in the direction perpendicular to the voltage application direction. In this case, the electrodes 118A, 118B, 120A, and 120B are elastic members 118C and 120C, respectively. On the other hand, the suspension link 100 is disposed on both sides of the axis 110.

  In the second embodiment, when the vehicle is stopped, the electronic control unit 30 can reduce the vehicle so that the smaller the ratio V / Gbx is, the smaller the ratio V / Gbx is in the region where the ratio V / Gbx of the vehicle speed V to the deceleration Gbx of the vehicle is small. The target deceleration Gt of the vehicle is reduced and corrected, and the braking force of each wheel is controlled so that the target deceleration Gta of the vehicle after the reduction correction is achieved at the normal rear wheel distribution ratio by the braking force of the front and rear wheels, By reducing the spring constant of the elastic variable members 118 and 120, the longitudinal compliance of the vehicle is increased. In this case, the ratio V / Gbx is such that the spring constant of the elastic variable members 118 and 120, and hence the longitudinal compliance of the vehicle, increases as the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx when the vehicle is stopped is reduced. It is controlled according to.

  Next, a stop behavior control routine for the vehicle by controlling the braking force and controlling the front and rear support rigidity of the wheel in the second embodiment will be described with reference to the flowchart shown in FIG. In FIG. 10, the same steps as those shown in FIG. 2 are assigned the same step numbers as those shown in FIG.

  In the second embodiment, steps 10 to 50 are executed in the same manner as in the first embodiment, and when an affirmative determination is made in step 50, that is, it is determined that the vehicle is at a braking stop. In step 130, the target spring constant Kt of the rubber bushing device 102 of each wheel is calculated from the map corresponding to the graph shown in FIG. 12 based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx. When a negative determination is made in step 40 or 50, the target spring constant Kt of the rubber bush device 102 is set to its standard value Kto in step 140.

  In step 150, as in the case of step 80 of the above-described first embodiment, the target deceleration is reduced from the map corresponding to the graph shown in FIG. 4 based on the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx. The gain Kg of the braking force is calculated, and in step 160, the rear wheel distribution ratio Kr at the time of braking is calculated in a manner known in the art, as in step 60 of the first embodiment. Is done.

In step 170, the vehicle target deceleration Gt is corrected by the deceleration reduction gain Kg, as in step 100 of the first embodiment, so that the corrected vehicle target deceleration Gta is obtained. In step 180, the target braking pressure Pbtf for the left and right front wheels and the target braking pressure Pbtr for the left and right rear wheels are calculated according to the following equations 6 and 7, as in steps 70 and 110 of the first embodiment. The
Pbtf = KbGta (1-Kr) (6)
Pbtr = KbGtaKr (7)

  In step 190, as in step 120 of the first embodiment, the front wheel braking pressures Pfl and Pfr and the rear wheel braking pressures Prl and Prr are set to the target braking pressures Pbtf and Pbtr, respectively. The braking pressure is controlled, and in step 200, the spring constant of the rubber bushing device 102 of each wheel is controlled to become the target spring constant Kt.

  Thus, according to the illustrated second embodiment, if it is determined in steps 40 and 50 that the vehicle is at a braking stop, the ratio V / Gbx of the vehicle speed V to the vehicle deceleration Gbx is small in step 130. The target spring constant Kt of the rubber bushing device 102 of each wheel is calculated based on the ratio V / Gbx so that the target spring constant Kt of the rubber bushing device 102 of each wheel becomes smaller, and as a result, the smaller the ratio V / Gbx becomes. Since the longitudinal frequency of the vehicle can be increased by lowering the natural frequency in the longitudinal direction of the vehicle, the force in the turning direction of the vehicle body is reduced and the change in the longitudinal acceleration of the vehicle is reduced as in the first embodiment. By reducing the degree, the shock to the vehicle acceleration side felt by the occupant can be surely reduced.

  Further, according to the illustrated second embodiment, the braking force distribution before and after braking of the vehicle is not restricted to a special distribution as in the first embodiment described above. By effectively utilizing the above, it is possible to reduce the shock at the time of braking stop of the vehicle without deteriorating the running stability of the vehicle.

  In the illustrated second embodiment, when the vehicle is stopped, the corrected target deceleration Gta of the vehicle is calculated so that the smaller the ratio V / Gbx of the vehicle speed V to the deceleration Gbx of the vehicle is, the smaller the correction is. Since the braking force of each wheel is controlled so that the target deceleration Gta of the subsequent vehicle is achieved, the inertial force forward of the vehicle when the vehicle is stopped can be gradually reduced. This makes it possible to reliably reduce shocks to the vehicle deceleration side even when no braking force reduction operation is performed, which further reduces the shock to the vehicle acceleration side felt by the occupant when the vehicle body rolls back. can do.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the first embodiment described above, when braking of the vehicle is stopped, braking force is applied only to the left and right front wheels, and no braking force is applied to the left and right rear wheels. However, the vehicle is a rear wheel drive vehicle. In some cases, a modification may be made such that a braking force that reduces or cancels the creep torque is applied to the left and right rear wheels as drive wheels. Similarly, in a configuration in which braking force is applied only to the left and right rear wheels and braking force is not applied to the left and right front wheels when braking of the vehicle is stopped, if the vehicle is a front wheel drive vehicle, the creep torque is reduced or The canceling braking force may be applied to the left and right front wheels that are drive wheels. According to these modified examples, it is possible to effectively reduce the shock felt by the occupant when braking of the vehicle is stopped, and to effectively prevent the braking distance of the vehicle from being increased due to the creep torque.

  In each of the above-described embodiments, the target deceleration Gt of the vehicle is calculated based on the master cylinder pressure Pm and the depression stroke St of the brake pedal 26. However, the target deceleration Gt of the vehicle is For example, the calculation may be performed based on only the master cylinder pressure Pm or only the depression stroke St of the brake pedal 26.

  In each of the above-described embodiments, the vehicle target deceleration Gt is calculated as the driver's required deceleration based on the driver's braking operation amount. The device may be applied to a vehicle in which automatic braking is performed for the purpose of avoiding a collision or ensuring a safe inter-vehicle distance between preceding vehicles, in which case the target deceleration Gt of the vehicle is reduced by a driver's demand reduction. It may be calculated as the larger value of the speed and the required deceleration for automatic braking.

  In the second embodiment, the elastic variable members 118 and 120 are interposed in the rubber bushing device 102 at the vehicle body side end of the suspension link 100, and their spring constants are changed by controlling the applied voltage. The front-rear compliance of the vehicle is increased / decreased by, for example, the cavities 114 and 116 are formed as sealed spaces, the gas flow resistance between them is increased / decreased, and the cavities 114 and 116 Like the configuration in which the spring constant of the rubber bushing device 102 is changed by increasing or decreasing the pressure, the increase or decrease of the vehicle front-rear compliance may be achieved by any configuration that can increase or decrease the support rigidity of each wheel in the vehicle front-rear direction. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram illustrating a first embodiment of a vehicle stop behavior control device according to the present invention applied to a vehicle capable of controlling the front-rear distribution of braking force. 4 is a flowchart illustrating a vehicle stop behavior control routine based on braking force control according to the first embodiment. It is a flowchart which shows the subroutine of the target deceleration Gt calculation of the vehicle in step 20 of FIG. It is a graph which shows the relationship between ratio V / Gbx of the vehicle speed V with respect to deceleration Gbx of a vehicle, and the gain Kg of target deceleration reduction. It is a graph which shows the relationship between ratio V / Gbx of vehicle speed V with respect to deceleration Gbx of a vehicle, and rear-wheel distribution ratio Krs of braking force. It is a graph which shows the relationship between the depression stroke St of a brake pedal, and the target deceleration Gst. It is a graph which shows the relationship between the average value Pma of a master cylinder pressure, and target deceleration Gpt. It is a graph which shows the relationship between the last target deceleration Gtf and the weight (alpha) with respect to the target deceleration Gpt. It is a schematic block diagram which shows Example 2 of the stop behavior control apparatus of the vehicle by this invention applied to the vehicle provided with the front-back support rigidity variable apparatus of a wheel. 7 is a flowchart showing a vehicle stop behavior control routine based on control of braking force and control of front and rear support rigidity of a wheel in Embodiment 2. It is a front view which shows the rubber bush apparatus provided in the vehicle body side edge part of a suspension link. It is a graph which shows the relationship between ratio V / Gbx of the vehicle speed V with respect to deceleration Gbx of a vehicle, and the target spring constant Kt.

Explanation of symbols

20 braking device 28 master cylinder 30 electronic control device 40 vehicle speed sensor 42 longitudinal acceleration sensor 44 power circuit 100 suspension link 102 rubber bushing device 118, 120 elastic variable member

Claims (7)

  The vehicle includes: a means for determining when the vehicle brake is stopped; and a control means for controlling the vehicle front-rear compliance so that the vehicle front-rear compliance is greater than a value before the brake stop when the vehicle is stopped. Stop behavior control device.   2. The vehicle stop behavior control according to claim 1, wherein the control means increases the front-rear compliance of the vehicle by substantially allocating the braking force at the time of braking stop of the vehicle only to the front wheels or the rear wheels. apparatus.   3. The vehicle stop behavior control device according to claim 1, wherein the control means increases the vehicle front-rear compliance by reducing the wheel support rigidity in the vehicle front-rear direction when the vehicle is stopped. 3.   The vehicle has braking force control means for controlling the braking force of the wheel, and the braking force control means controls the braking force of the wheel so that the deceleration of the vehicle is smaller than the deceleration required of the vehicle when the braking of the vehicle is stopped. The vehicle stop behavior control device according to claim 1, wherein the vehicle stop behavior control device is controlled.   4. The vehicle stop behavior control device according to claim 1, wherein the braking force of the wheel is controlled so that the deceleration of the vehicle becomes smaller as the ratio of the vehicle speed to the deceleration of the vehicle becomes smaller.   The vehicle has driving wheels and non-driving wheels, and when the control means distributes the braking force at the time of braking stop of the vehicle substantially only to the non-driving wheels, the braking force for reducing the creep torque is applied to the driving wheels. The vehicle stop behavior control device according to claim 2, wherein the vehicle stop behavior control device is provided. The means for determining when the vehicle is stopped is determined to be when the vehicle is stopped when the vehicle speed is equal to or less than a reference value in a situation where a braking force is applied to the wheels. The vehicle stop behavior control device according to any one of Items 6 to 6.

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