JP2005343185A - Braking force control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the braking force so as to meet the braking requirement of a driver effectively while the rate of rising of the braking force is prevented from becoming excessive to cause the driver/passenger of the vehicle to feel a shock. <P>SOLUTION: The provisional target deceleration Gtpro of the vehicle is computed on the basis of the brake operation amount of the driver (S20), and the prescribed time Tco is computed on the basis of the vehicle speed V (S80), and when the prescribed time Tco has not elapsed (S100), the target deceleration Gtlim after limitation of the rate of increase is computed as the sum of the previous value Gttf of the final target deceleration Gtt and the limited increase amount dGt of the target deceleration (S110, S150). For the prescribed time Tco, the final target deceleration Gtt is set to either Gtpro or Gtlim whichever is the greatest (S170, S190), whereby the rate of increase of Gtt is limited, and when the prescribed time Tco has passed, a comparatively steep increase of Gtt is admitted (S140). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle braking force control device, and more specifically, obtains a target braking control amount based on a driver's braking operation amount, and controls the braking force of each vehicle based on the target braking control amount. Related to the control device.

As one of braking force control devices for vehicles such as automobiles, the amount of braking operation of a driver, such as master cylinder pressure and brake pedal depression stroke, as described in the following Patent Document 1 filed by the applicant of the present application. The target braking force of the vehicle is calculated based on the driver's braking demand, the target braking force of each wheel is determined based on the target deceleration, and the braking device is controlled so that the braking force of each wheel becomes the corresponding target braking force. A so-called electronically controlled braking force control apparatus is conventionally known.
JP 2000-177557 A

  According to the braking force control apparatus as described above, the relationship of the braking force of each wheel with respect to the driver's braking operation amount, that is, the boost ratio can be freely set. It is difficult to optimally determine the relationship of the braking force increase / decrease, that is, the response of the braking force increase / decrease. For example, when the force increase ratio is increased, the response of increasing / decreasing the braking force also increases, so that the rate of increase of the braking force becomes excessive at the start of braking and the vehicle occupant may feel a shock. On the other hand, if the boost ratio is lowered, the response to increase / decrease in braking force also decreases, so the braking effectiveness decreases, the braking force becomes insufficient, and the braking distance of the vehicle becomes longer. May not be satisfied sufficiently.

  The present invention has been made in view of the above-described problems in a conventional braking force control device for a vehicle, and a main problem of the present invention is that it appropriately controls the increase rate of the braking force. This is to control the braking force so as to effectively satisfy the driver's braking request while preventing the vehicle occupant from feeling a shock due to an excessive increase in power.

  According to the present invention, the main problem described above is that the target braking control amount is obtained based on the configuration of claim 1, that is, the braking operation amount of the driver, and the braking force of each wheel is controlled based on the target braking control amount. In the vehicle braking force control device, the increase rate of the target braking control amount is limited to a first limit value or less for a predetermined time after the driver starts the braking operation, and when the predetermined time has elapsed, This is achieved by a braking force control device for a vehicle, characterized in that the rate of increase of the target braking control amount is limited to a second limit value that is larger than the first limit value.

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, at least the first limit value is higher when the vehicle speed is higher than when the vehicle speed is low. It is configured to be variably set according to the vehicle speed so as to be larger (configuration 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 predetermined time is shorter when the vehicle speed is high than when the vehicle speed is low. (Structure of claim 3).

  Further, according to the present invention, in order to effectively achieve the main problems described above, in the configuration of the first to third aspects, a restriction on the increase rate of the target braking control amount is limited to the first in the initial stage of braking. It is comprised so that it may be gentler than the restriction | limiting by the limit value of (structure of Claim 4).

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 4, the target braking control amount becomes equal to or greater than the restriction start reference value after the driver starts the braking operation. The restriction on the increase rate of the target braking control amount is made gentler than the restriction by the first restriction value.

  Further, according to the present invention, in order to effectively achieve the main problem described above, in the configuration of the above-described first to fifth aspects, the increase rate of the target braking control amount before the predetermined time elapses. The limit is configured to be more gentle than the limit by the first limit value and to be more severe than the limit by the second limit value (configuration of claim 6).

  According to the present invention, in order to effectively achieve the main problems described above, the target braking control amount is obtained as a target deceleration of the vehicle in the configuration of claims 1 to 6. (Configuration of Claim 7).

  According to the present invention, in order to effectively achieve the main problems described above, the braking force of each wheel is controlled by controlling the corresponding braking pressure. The target braking control amount is obtained as a target braking pressure for each wheel (configuration of claim 8).

  According to the configuration of the first aspect, the increase rate of the target braking control amount is limited to the first limit value or less for a predetermined time after the driver starts the braking operation, and the target braking control is performed when the predetermined time elapses. Since the increase rate of the amount is limited to the second limit value that is larger than the first limit value, even if the driver performs a sudden braking operation, the increase of the braking force is suppressed for a predetermined time. It is possible to reliably prevent the vehicle occupant from feeling a shock due to an excessive rate of increase in braking force at the start of braking, etc., and to effectively increase the braking force after a predetermined time has elapsed. This can reduce the braking effectiveness or increase the braking distance of the vehicle due to insufficient braking force and the driver's braking demands cannot be sufficiently satisfied. It can be surely prevented.

  According to the second aspect of the present invention, at least the first limit value is variably set according to the vehicle speed so as to be larger when the vehicle speed is high than when the vehicle speed is low. It is possible to reliably prevent a vehicle occupant from feeling a shock due to a sudden rise in the vehicle's speed, and to reduce the braking effectiveness and braking force in the middle and high vehicle speed range and to the driver's braking due to this. It can be surely prevented that the request is not satisfied.

  According to the third aspect of the present invention, since the predetermined time is shorter when the vehicle speed is high than when the vehicle speed is low, the vehicle occupant shocks due to a sudden increase in braking force in the low vehicle speed range. While reliably preventing a feeling, it is possible to surely prevent the braking effect and braking force in the middle and high vehicle speed range from being insufficient and the driver's braking request from being satisfied due to this.

  According to the fourth aspect of the present invention, since the restriction on the increase rate of the target braking control amount is made gentler than the restriction by the first restriction value at the initial stage of braking, the target braking control over a predetermined time from the beginning of braking is performed. Compared to when the restriction on the rate of increase of the amount is started, it is possible to ensure a situation where the braking force can be generated reliably from the initial stage of braking, and to reliably prevent a delay in the response of the braking force generation.

  According to the fifth aspect of the present invention, the restriction on the increase rate of the target braking control amount is more gentle than the restriction by the first restriction value until the target braking control amount after the driver starts the braking operation becomes equal to or greater than the restriction start reference value. Therefore, compared with the case where the restriction on the increase rate of the target braking control amount is made gentler than the restriction by the first restriction value for a preset time from the beginning of the braking, it is surely controlled without excess or deficiency. A situation where power can be generated is ensured, and a delay in response to generation of braking force can be reliably prevented.

  According to the sixth aspect of the present invention, the restriction on the increase rate of the target braking control amount is gentler than the restriction by the first restriction value and more severe than the restriction by the second restriction value before the predetermined time elapses. Therefore, when the predetermined time elapses, the restriction on the increase rate of the target braking control amount changes abruptly, which effectively increases the braking force of each wheel. Can be prevented.

  According to the seventh aspect of the present invention, since the target braking control amount is obtained as the target deceleration of the vehicle, it is possible to reliably prevent the passenger from feeling a shock due to the rapid increase in the deceleration of the vehicle. In addition, since it is only necessary to limit the increase rate of the target braking control amount and it is not necessary to limit the increase rate of the target braking pressure of each wheel, the control is simplified as compared with the configuration of the eighth aspect. be able to.

  According to the eighth aspect of the present invention, the braking force of each wheel is controlled by controlling the corresponding braking pressure, and the target braking control amount is obtained as the target braking pressure of each wheel. It is possible to reliably prevent the occupant from feeling a shock due to the sudden rise.

[Preferred embodiment of problem solving means]
According to one preferable aspect of the present invention, in the structure according to the first to eighth aspects, the second limit value is infinite (preferred aspect 1).

  According to another preferred embodiment of the present invention, in the configuration of claim 4 or 5, the limit value of the limit for the increase rate of the target braking control amount at the initial stage of braking is configured to be infinite ( Preferred embodiment 2).

  According to another preferred aspect of the present invention, in the configuration of claim 6, the target braking control amount increases when an increase rate limit time shorter than a predetermined time after the driver starts braking operation elapses. The rate limit is configured to be more gentle than the limit by the first limit value and more severe than the limit by the second limit value (preferred embodiment 3).

  According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 3, the limit value of the limit for the increase rate of the target braking control amount after the increase rate limit time elapses is a constant value. (Preferred embodiment 4).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 3, the limit value of the limit for the increase rate of the target braking control amount after the increase rate limit time elapses gradually increases as time elapses. (Preferred aspect 5)

  According to another preferred aspect of the present invention, in the configuration of the first to eighth aspects, the braking force is configured to be generated by pressing the pressing member against the pressed member (preferably). Aspect 6).

  According to another preferable aspect of the present invention, in the structure of the preferable aspect 6, the pressing force of the pressing member against the pressed member is configured to be controlled by controlling the braking pressure (preferably. Aspect 7).

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

  FIG. 1 is a schematic configuration diagram showing a hydraulic circuit of a first embodiment of a vehicle braking force control apparatus according to the present invention and a block diagram showing a control system. In FIG. 1, the solenoid of each valve is not shown for the sake of simplicity.

  In FIG. 1, reference numeral 10 denotes an electrically controlled hydraulic brake device. The brake device 10 includes a master cylinder 14 that pumps brake oil in response to a driver's depressing operation of the brake pedal 12. Have. 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 18 for the left front wheel and a brake hydraulic pressure control conduit for the right front wheel, respectively. One end of 20 is connected. Wheel cylinders 22FL and 22FR for controlling the braking force of the left front wheel and the right front wheel are connected to the other ends of the brake hydraulic pressure control conduits 18 and 20, respectively.

  In the middle of the brake hydraulic pressure supply pipes 18 and 20, normally open type electromagnetic on / off valves (master cut valves) 24L and 24R are provided, respectively. The electromagnetic on / off valves 24L and 24R are respectively connected to the first master cylinder chamber 14A and the second master cylinder chamber 14A. It functions as a shut-off valve that controls communication between the master cylinder chamber 14B and the corresponding wheel cylinders 22FL and 22FR. A wet stroke simulator 28 is connected to the brake hydraulic pressure supply conduit 18 between the master cylinder 14 and the electromagnetic opening / closing valve 24FL via a normally closed electromagnetic opening / closing valve 26.

  A reservoir 30 is connected to the master cylinder 14, and one end of a hydraulic pressure supply conduit 32 is connected to the reservoir 30. An oil pump 36 driven by an electric motor 34 is provided in the middle of the hydraulic supply conduit 32, and an accumulator 38 that accumulates high-pressure hydraulic pressure is connected to the hydraulic supply conduit 32 on the discharge side of the oil pump 36. One end of a hydraulic discharge conduit 40 is connected to the hydraulic supply conduit 32 between the reservoir 30 and the oil pump 36.

  Although not shown in FIG. 1, a conduit is provided for connecting the suction-side hydraulic supply conduit 32 and the discharge-side hydraulic supply conduit 32 of the oil pump 36, and an accumulator 38 is provided in the middle of the conduit. A relief valve is provided that opens when the pressure exceeds a reference value and returns oil from the discharge-side hydraulic supply conduit 32 to the suction-side hydraulic supply conduit 32.

  The hydraulic pressure supply conduit 32 on the discharge side of the oil pump 36 is connected to the brake hydraulic pressure supply conduit 18 between the electromagnetic on-off valve 24L and the wheel cylinder 22FL by a hydraulic control conduit 42, and the electromagnetic on-off valve 24R and the wheel by a hydraulic control conduit 44. It is connected to a brake hydraulic pressure supply conduit 20 between the cylinder 22FR, a hydraulic control conduit 46 to a left rear wheel wheel cylinder 22RL, and a hydraulic control conduit 48 to a right rear wheel wheel cylinder 22RR. .

  Normally closed electromagnetic linear valves 50FL, 50FR, 50RL, and 50RR are provided in the middle of the hydraulic control conduits 42, 44, 46, and 48, respectively. The hydraulic control conduits 42, 44, 46, 48 on the side of the wheel cylinders 22FL, 22FR, 22RL, 22RR with respect to the linear valves 50FL, 50FR, 50RL, 50RR are connected to the hydraulic discharge conduit 40 by the hydraulic control conduits 52, 54, 56, 58, respectively. And normally closed electromagnetic linear valves 60FL, 60FR, 60RL, and 60RR are provided in the middle of the hydraulic control conduits 52, 54, 56, and 58, respectively.

  The linear valves 50FL, 50FR, 50RL, and 50RR function as pressure increase valves (holding valves) for the wheel cylinders 22FL, 22FR, 22RL, and 22RR, respectively. The linear valves 60FL, 60FR, 60RL, and 60RR are wheel cylinders 22FL, 22FR, 22RL, and The linear valves function as pressure reducing valves for 22RR, so that these linear valves form a pressure increasing / decreasing control valve for controlling supply / discharge of high pressure oil to / from each wheel cylinder from the accumulator 38 in cooperation with each other.

  As shown in FIG. 1, a brake hydraulic pressure control conduit 18 between the first master cylinder chamber 14A and the electromagnetic on-off valve 24L detects a pressure in the control conduit as a first master cylinder pressure Pm1. One pressure sensor 66 is provided. Similarly, the brake pressure control conduit 20 between the second master cylinder chamber 14B and the electromagnetic on-off valve 24R is provided with a second pressure sensor 68 for detecting the pressure in the control conduit as the second master cylinder pressure Pm2. It has been. The brake pedal 12 is provided with a stroke sensor 70 for detecting a brake pedal depression stroke St by a driver, and a pressure for detecting the pressure in the conduit as an accumulator pressure Pa is provided in a hydraulic supply conduit 32 on the discharge side of the oil pump 34. A sensor 72 is provided.

  Each of the brake hydraulic pressure supply pipes 18 and 20 between the electromagnetic on-off valves 24L and 24R and the wheel cylinders 22FL and 22FR has a pressure in the corresponding pipe that is a pressure in the wheel cylinders 22FL and 22FR (braking pressure of the left and right front wheels) Pbfl. , Pressure sensors 74FL and 74FR for detecting Pbfr are provided. Further, in the hydraulic control conduits 46 and 48 between the electromagnetic on-off valves 50RL and 50RR and the wheel cylinders 22RL and 22RR, respectively, the pressure in the corresponding conduit is set to the pressure in the wheel cylinders 22RL and 22RR (braking pressure of the left and right rear wheels). Pressure sensors 74RL and 74RR that detect Pbrl and Pbrr are provided.

  The electromagnetic open / close valves 24L and 24R, the electromagnetic open / close valve 26, the motor 34, the linear valves 50FL, 50FR, 50RL, 50RR, and the linear valves 60FL, 60FR, 60RL, 60RR are, as will be described in detail later, an electronic control device 78 for braking force control. Controlled by The electronic control unit 78 includes a microcomputer 80 and a drive circuit 82.

  Although not shown in detail in FIG. 1, the microcomputer 80 includes, for example, a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output port device. These may have a general configuration in which they are connected to each other by a bidirectional common bus.

  In the microcomputer 80, a signal indicating the first master cylinder pressure Pm1 and the second master cylinder pressure Pm2 from the pressure sensors 66 and 68, a signal indicating the depression stroke St of the brake pedal 12 from the stroke sensor 70, and a pressure sensor 72, respectively. A signal indicating the accumulator pressure Pa, a signal indicating the pressure Pbi (i = fl, fr, rl, rr) in the wheel cylinders 22FL to 22RR and a signal indicating the vehicle speed V from the vehicle speed sensor 76 are input from the pressure sensors 74FL to 74RR, respectively. Is done.

  When no drive current is supplied to each electromagnetic open / close valve, each linear valve, and the motor 34, the electromagnetic open / close valves 24L and 24R are maintained open, and the electromagnetic open / close valve 26, linear valves 50FL, 50FR, 50RL, 50RR, The linear valves 60FL, 60FR, 60RL, and 60RR are kept closed (non-control mode).

  The microcomputer 80 stores a control routine according to the flowcharts shown in FIGS. 2 and 3 as will be described later, and the microcomputer 80 uses the average values Pm of the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 as shown in FIG. The vehicle target deceleration Gpt is calculated from a map corresponding to the graph shown in FIG. 7, and the vehicle target deceleration Gst is calculated based on the stepping stroke St detected by the stroke sensor 70 from the map corresponding to the graph shown in FIG. Is calculated.

  Then, the microcomputer 80 calculates a weight α (0 ≦ α ≦ 1.0) for the target deceleration Gst from the map corresponding to the graph shown in FIG. 8 based on the target deceleration Gpt, and calculates the target deceleration Gpt and the target deceleration Gpt. The provisional target deceleration (driver's required deceleration) Gtpro is calculated as a weighted sum of the deceleration Gst. The decelerations such as the target deceleration Gst, the target deceleration Gpt, and the provisional target deceleration Gtpro are calculated with the vehicle acceleration direction being positive and are negative values.

  Further, the microcomputer 80 calculates a final target deceleration Gtt whose rate of increase is limited based on the provisional target deceleration Gtpro, and based on the final target deceleration Gtt, the target braking pressure Pbti (i = fl, fr, rl) of each wheel. , Rr), and the target drive current Iti (i = fl, fr, rl, rr) for the linear valve 50FL-50RR or 60FL-60RR is calculated based on the deviation between the target braking pressure Pbti and the actual braking pressure Pbi. The braking force of each wheel is controlled by controlling the braking pressure Pbi of each wheel to become the target braking pressure Pbti by applying a driving current to each linear valve based on the target driving current Iti.

  In this case, the microcomputer 80 controls the valve opening amounts of the linear valves 50FL, 50FR, 50RL, and 50RR according to the target wheel cylinder pressure Pti when the braking control mode is the pressure increasing mode, and the braking control mode is the pressure reducing mode. In some cases, the valve opening amounts of the linear valves 60FL, 60FR, 60RL, and 60RR are controlled according to the target wheel cylinder pressure Pti. When the braking control mode is the holding mode, the linear valves 50FL to 50RR and 60FL to 60RR are closed. maintain.

  Particularly in the first embodiment, when the final target deceleration Gtt is larger than the restriction start reference value Gto (negative constant) as in the braking start, the microcomputer 80 responds to the increase rate of the final target deceleration Gtt. The limit is moderated, and the limit on the increase rate of the final target deceleration Gtt is tightened for a predetermined time Tco from the time when the final target deceleration Gtt becomes less than or equal to the limit start reference value Gto. The restriction on the rate of increase of the target deceleration Gtt is moderated.

  Next, 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 when the electronic control unit 78 is activated, and is repeatedly executed at predetermined time intervals until an ignition switch (not shown) is turned off.

  First, in step 10, signals indicating the master cylinder pressures Pm1 and Pm2 detected by the pressure sensors 66 and 68 are read. In step 20, the master cylinder pressure Pm1 is read according to the flowchart shown in FIG. , Pm2 and the depression stroke St are calculated as a temporary target deceleration Gtpro.

  In step 30, a determination is made as to whether or not the provisional target deceleration Gtpro is a value greater than or equal to 0, that is, whether or not a braking operation is being performed by the driver, and a negative determination is made. In some cases, the process proceeds to step 60. If an affirmative determination is made, in step 40, the target deceleration Gtlim after the increase rate limit, the final target deceleration Gtt, the limit increase dGt of the target deceleration for limiting the increase rate, The count values Tc of the timers for measuring a predetermined time are reset to 0, respectively, and in step 50, each electromagnetic on-off valve and the like are set to the non-control mode.

  In step 60, it is determined whether or not the final target deceleration Gtt is larger than the limit start reference value Gto (negative constant), that is, whether or not braking is started, and an affirmative determination is made. In step 70, the limit increase amount dGt of the target deceleration is set to the value dGto (negative constant) at the start of braking, and when a negative determination is made, in step 80, based on the vehicle speed V, FIG. A predetermined time Tco is calculated from the map corresponding to the graph shown in FIG.

  In step 100, it is determined whether or not the count value Tc of the timer is greater than or equal to the reference value Tco, that is, whether or not a predetermined time Tco has elapsed. If negative determination is made, step 110 is performed. Then, based on the vehicle speed V, the target deceleration limited increase amount dGt is calculated from the map corresponding to the graph shown in FIG. 5, and when a positive determination is made, in step 140, the target deceleration limit increase amount. dGt is set to a standard value dGts (a negative constant smaller than the value calculated in step 110).

  In step 150, Gttf is used as the previous value of the final target deceleration Gtt according to Equation 1 below.

Thus, the target deceleration Gtlim after the increase rate limit is calculated.
Gtlim = Gttf + dGt (1)

  In step 160, it is determined whether or not the provisional target deceleration Gtpro is smaller than the target deceleration Gtlim after the increase rate limitation, that is, whether or not the increase rate of the target deceleration over a predetermined time Tco should be limited. When a positive determination is made, the timer count value Tc is incremented by ΔTc using ΔTc as the cycle time of the flowchart shown in FIG. 2 in step 170, and when a negative determination is made, step At 180, the timer count value Tc is reset to zero.

In step 190, the final target deceleration Gtt is calculated as the larger value of the provisional target deceleration Gtpro and the target deceleration Gtlim after the increase rate limit. In step 200, the final target deceleration Gtt is calculated. The coefficient of the target braking pressure (target wheel cylinder pressure) of each wheel is Ki (i = fl, fr, rl, rr), and the target braking pressure Pti (i of each wheel is determined according to the following equation 2 based on the final target deceleration Gtt = Fl, fr, rl, rr) is calculated, and the braking pressure Pbi of each wheel is controlled to become the corresponding target braking pressure Pti.
Pti = KiGtt (2)

  Next, a calculation routine for the temporary target deceleration Gtpro will be described with reference to the flowchart shown in FIG.

  First, at step 22, the target deceleration Gst based on the depression stroke Sp is calculated from the map corresponding to the graph shown in FIG. 6, and at step 24, the map corresponding to the graph shown in FIG. A target deceleration Gpt based on the master cylinder pressure Pm is calculated.

In step 26, the weight α for the target deceleration Gpt based on the master cylinder pressure Pm is calculated from the map corresponding to the graph shown in FIG. 8 based on the final target deceleration Gt calculated in the previous cycle. In step 28, the provisional target deceleration Gtpro of the vehicle is calculated as a weighted sum of the target deceleration Gpt and the target deceleration Gst according to the following equation 3.
Gtpro = α · Gpt + (1-α) Gst (3)

  Thus, according to the first embodiment shown in the drawing, in step 20, the temporary target deceleration Gtpro of the vehicle is calculated based on the amount of braking operation of the driver, and in step 30, whether the braking operation is performed by the driver. In step 60, it is determined whether or not it is time to start braking. If it is time to start braking, step 70 is performed until the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. At this time, the limit increase amount dGt of the target deceleration is set to the value dGto at the start of braking, thereby permitting a relatively steep increase in braking pressure at the start of braking.

  If it is determined in step 60 that it is not at the start of braking, a predetermined time Tco is calculated based on the vehicle speed V in step 80, and it is determined whether or not the predetermined time Tco has elapsed in step 100. When the predetermined time Tco has not elapsed, the limit increase dGt of the target deceleration is calculated in step 110, and the previous value Gttf of the final target deceleration Gtt and the target deceleration are calculated in step 150. The target deceleration Gtlim after the increase rate limit is calculated as the sum of the limit increase amount dGt.

  In step 160, it is determined whether or not to limit the increase rate of the target deceleration over a predetermined time Tco. When an affirmative determination is made, in steps 170 and 190, the predetermined time Tco is determined. The final target deceleration Gtt is set to the larger value of the provisional target deceleration Gtpro and the target deceleration Gtlim after the increase rate is limited, thereby increasing the increase rate of the final target deceleration Gtt over a predetermined time Tco. Is limited to an increase rate corresponding to the limit increase dGt of the target deceleration.

  Further, when a predetermined time Tco elapses, an affirmative determination is made in step 100, and the limit increase dGt of the target deceleration is set to the standard value dGts in step 140, so that the final target deceleration Gtt is relatively steep. Increase is allowed.

  For example, FIG. 11A shows an example of a change in restriction on the increase rate of the target deceleration in the first embodiment, that is, an example in which the final target deceleration Gtt changes maximum within the range of the increase rate limit. It is a graph to show. As shown in FIG. 11A, when the braking operation is started by the driver at the time t1, and the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto at the time t2, the time t2 Further, the increase rate of the final target deceleration Gtt is limited to the increase rate corresponding to the limit increase amount dGt over a predetermined time Tco until time t4, and the increase rate of the final target deceleration Gtt is the standard value dGts after time t4. The rate of increase is reduced.

  Therefore, according to the first embodiment shown in the figure, when the braking operation is started by the driver, the final target for each cycle over a predetermined time Tco from the time when the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. Even when the increase amount of the deceleration Gtt is limited to the limit increase amount dGt or less, and the braking operation amount is suddenly increased by the driver, the braking pressure rapidly increases and the pressed member such as a brake disk is pressed. It is possible to reliably prevent a vehicle occupant from feeling a shock due to a sudden increase in the pressing force of a pressing member such as a brake pad and a sudden increase in braking force.

  Further, according to the first embodiment shown in the figure, when the predetermined time Tco elapses, the limit increase amount dGt of the target deceleration is set to the standard value dGts, and a relatively steep increase in the final target deceleration Gtt is allowed. When the driver's braking demand is high, the braking force can be reliably increased, which effectively prevents the driver from feeling that the braking effect is reduced or the braking force is insufficient or that the braking distance of the vehicle becomes excessively long. Can be prevented.

  FIG. 9 is a flowchart showing a main part of a braking force control routine in the second embodiment of the vehicle braking force control apparatus according to the present invention. In FIG. 9, the same steps as those shown in FIG. 2 are assigned the same step numbers as those shown in FIG. The same applies to 10).

  In the second embodiment, steps 10 to 80, 100, 110, and 140 to 200 are executed in the same manner as in the first embodiment, and n is executed in step 90 executed after step 80. The reference value Tcm is calculated as Tco / n as a positive constant of about 2, and it is determined whether or not the timer count value Tc is greater than or equal to the reference value Tcm. The process proceeds to step 100 when an affirmative determination is made.

  If an affirmative determination is made in step 100, the process proceeds to step 140. If a negative determination is made, the limit increase amount dGt of the target deceleration is calculated in step 120 at dGtm (in step 110). Negative constant smaller than the standard value dGts).

  Thus, according to the illustrated second embodiment, it is determined in step 90 whether or not the increase rate limit time Tcm has elapsed. If the increase rate limit time Tcm has not elapsed, the target decrease in step 110 is performed. The speed limit increase amount dGt is calculated, and in step 150, the target deceleration Gtlim after the increase rate limit is calculated as the sum of the previous target value Gttf of the final target deceleration Gtt and the target deceleration limit increase amount dGt. .

  In step 160, it is determined whether or not the increase rate limit of the target deceleration over the increase rate limit time Tcm should be executed. If an affirmative determination is made, the increase rate limit is determined in steps 170 and 190. The final target deceleration Gtt over the time Tcm is set to the larger value of the provisional target deceleration Gtpro and the target deceleration Gtlim after the increase rate limit, whereby the final target deceleration Gtt over the increase rate limit time Tcm. The increase rate is limited to an increase rate corresponding to the limit increase amount dGt of the target deceleration.

  In step 100, when it is determined that the predetermined time Tco has not elapsed, the limit increase amount dGt of the target deceleration is smaller than the value calculated in step 110 in step 120. The negative constant larger than the standard value dGts is set to dGtm, and the restriction on the increase rate of the final target deceleration Gtt is relaxed to some extent.

  Further, when a predetermined time Tco elapses, an affirmative determination is made in step 100, and the limit increase dGt of the target deceleration is set to the standard value dGts in step 140, so that the final target deceleration Gtt is relatively steep. Increase is allowed.

  For example, as shown in FIG. 11 (B), when the driver starts a braking operation at time t1, and the final target deceleration Gtt becomes equal to or less than the restriction start reference value Gto at time t2, The increase rate of the final target deceleration Gtt is limited to the increase rate corresponding to the limit increase amount dGt calculated in step 110 over the increase rate limit time Tcm from t2 to time t3, and from time t3 to time t4. The increase rate of the final target deceleration Gtt is limited to the increase rate corresponding to the limit increase amount dGtm over time Tco-Tcm, and the increase rate of the final target deceleration Gtt corresponds to the standard value dGts after time t4. To be relaxed.

  Therefore, according to the illustrated second embodiment, when the braking operation is started by the driver, the final target deceleration for each cycle for a predetermined time Tco from the time when the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. Even when the increase amount of the deceleration Gtt is limited to the limit increase amount dGt or less, and the braking operation amount is suddenly increased by the driver, the braking pressure rapidly increases and the pressed member such as a brake disk is pressed. It is possible to reliably prevent a vehicle occupant from feeling a shock due to a sudden increase in the pressing force of a pressing member such as a brake pad and a sudden increase in braking force.

  In particular, according to the illustrated embodiment 2, when the increase rate limit time Tcm elapses from the time when the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto, the limit on the increase rate of the final target deceleration Gtt is relaxed to some extent. Therefore, it is effective that the limit on the increase rate of the final target deceleration Gtt changes abruptly when the predetermined time Tco elapses, and the braking force of each wheel suddenly increases and changes due to this. Can be prevented.

  FIG. 10 is a flowchart showing a main part of a braking force control routine in the third embodiment of the vehicle braking force control apparatus according to the present invention.

  In the third embodiment, steps 10 to 110 and steps 140 to 200 are executed in the same manner as in the second embodiment, and when a negative determination is made in step 100, in step 130 The previous value of the target deceleration limit increase amount dGt is set to dGtf, ΔGt is a negative constant, and the target deceleration limit increase amount dGt is set to the sum of the previous value dGtf and ΔGt. The absolute value of the limit increase dGt of the target deceleration is gradually increased until the predetermined time Tco elapses after the increase rate limit time Tcm elapses from the time when Gtt becomes equal to or less than the limit start reference value Gto.

  For example, as shown in FIG. 11C, if the driver starts a braking operation at time t1, and the final target deceleration Gtt becomes equal to or less than the restriction start reference value Gto at time t2, The increase rate of the final target deceleration Gtt is limited to the increase rate corresponding to the limit increase amount dGt calculated in step 110 over the increase rate limit time Tcm from t2 to time t3, and from time t3 to time t4. The increase rate of the final target deceleration Gtt is limited to the increase rate corresponding to the limit increase amount dGtf + ΔGt over time Tco-Tcm, and after the time t4, the increase rate of the final target deceleration Gtt corresponds to the standard value dGts. To be relaxed.

  Therefore, according to the third embodiment shown in the figure, as in the first and second embodiments described above, even when the amount of braking operation is suddenly increased by the driver, the braking pressure rapidly increases, It is possible to reliably prevent a vehicle occupant from feeling a shock due to a sudden increase in pressing force of a pressing member such as a brake pad against the pressed member and a sudden increase in braking force.

  In particular, according to the illustrated embodiment 3, when the increase rate limit time Tcm elapses from the time when the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto, the limit on the increase rate of the final target deceleration Gtt is gradually relaxed. Therefore, when the predetermined time Tco elapses, the limit on the increase rate of the final target deceleration Gtt changes abruptly, and as a result, the braking force of each wheel suddenly increases and changes as described above. This can be prevented more effectively than in the case of the second embodiment.

  According to each of the illustrated embodiments, the predetermined time Tco is variably set according to the vehicle speed V so that the predetermined time Tco becomes shorter as the vehicle speed V is higher. As the vehicle speed V increases, it is variably set according to the vehicle speed V so that the vehicle occupant is surely prevented from feeling a shock due to a sudden increase in braking force at low vehicle speeds. In addition, it is possible to reliably prevent the braking effect and the braking force from being insufficient in the middle and high vehicle speed ranges and the driver's braking request from being satisfied due to this.

  Further, according to the illustrated embodiments, the target deceleration limited increase amount dGt is variably set according to the vehicle speed V so that the absolute value increases as the vehicle speed V increases, and the final target deceleration Gtt based on the limit increase amount dGt is set. Since the limit on the rate of increase is variably set according to the vehicle speed V so that the higher the vehicle speed V is, the vehicle occupant is shocked due to the sudden increase in braking force in the low vehicle speed range. It is possible to reliably prevent the driver from feeling uncomfortable and to reliably prevent the braking effectiveness and braking force in the middle and high vehicle speed range from being insufficient and the driver's braking request from being satisfied. it can.

  Further, according to the embodiment shown in the drawing, at the start of braking, the limit increase dGt of the target deceleration is set to the value dGto at the start of braking until the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. Since a relatively steep rise in pressure is allowed, for example, compared with the case where the restriction on the increase rate of the target deceleration over a predetermined time Tco is started from the beginning of braking, the inside of the wheel cylinder of each wheel is surely Thus, it is possible to reliably prevent a delay in response to the generation of braking force.

  Further, according to the embodiment shown in the drawing, at the start of braking, the limit increase dGt of the target deceleration is set to the value dGto at the start of braking until the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. Since a relatively steep increase in pressure is allowed, for example, compared to a case where a relatively steep increase in braking pressure is allowed for a preset time from the beginning of braking, the pressure in the wheel cylinder of each wheel is The initial pressurization can be performed without excess or deficiency.

  Further, according to the illustrated embodiments 2 and 3, the time Tcm until the relaxation of the restriction on the increase rate of the final target deceleration Gtt is started and the time Tco− when the restriction on the increase rate of the final target deceleration Gtt is relaxed. Since Tcm is variably set according to the predetermined time Tco so that it becomes shorter as the predetermined time Tco is shorter, the time until the relaxation of the restriction on the increase rate of the final target deceleration Gtt is started and the final target deceleration Gtt. As compared with the case where the time for which the restriction on the increase rate of the vehicle is relaxed is constant, the braking force of each wheel is effectively prevented from rapidly increasing when the predetermined time Tco has elapsed. , To ensure that the vehicle occupants do not feel a shock due to a sudden increase in braking force at low vehicle speeds. The driver ’s braking request The Tasa is not able to reliably prevent.

  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 above-described embodiments, the target braking control amount calculated based on the driver's braking operation amount is the target deceleration of the vehicle, but the target braking control amount is the target braking pressure of each wheel. The increase rate of the target braking pressure of each wheel may be limited in the same manner as the limitation of the increase rate of the target deceleration in each of the above-described embodiments.

  In each of the above-described embodiments, at the start of braking, the limit increase dGt of the target deceleration is set to the value dGto at the start of braking until the final target deceleration Gtt becomes equal to or less than the limit start reference value Gto. When the time Tco elapses, the target deceleration limit increase amount dGt is set to the standard value dGts. However, the limit of the target deceleration increase rate at the start of braking or after a predetermined time elapses is infinite ( Unlimited), and the restriction on the increase rate of the target deceleration at the start of braking may be omitted.

  In each of the above-described embodiments, the predetermined time Tco is calculated from the map corresponding to the graph shown in FIG. 4 in step 80 based on the vehicle speed V. The limit increase amount dGt of the target deceleration is calculated from the map corresponding to the graph shown in FIG. 5, but the predetermined time Tco and the limit increase amount dGt are based on the vehicle speed at the start of limiting the increase rate. The predetermined time Tco and the limit increase amount dGt may be set as a constant.

  In each of the above-described embodiments, the temporary target deceleration Gtpro as the driver's required deceleration is calculated based on the average value Pma of the master cylinder pressures Pm1, Pm2 and the brake pedal depression amount St, and each wheel is calculated. The target braking pressure Pti is calculated based on the target deceleration with a limited increase rate. However, the calculation of the target deceleration and the target braking pressure of each wheel itself does not form the gist of the present invention. Rather, it may be performed in any manner known in the art.

1 is a schematic configuration diagram showing a hydraulic circuit of a first embodiment of a vehicle braking force control apparatus according to the present invention and a block diagram showing a control system; 3 is a flowchart showing a braking force control routine in the first embodiment. FIG. 3 is a flowchart showing a provisional target deceleration routine executed in step 20 of the flowchart shown in FIG. 2. FIG. It is a graph which shows the relationship between the vehicle speed V and predetermined time Tco. It is a graph which shows the relationship between the vehicle speed V and the limit increase amount dGt of a target deceleration. 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 depression stroke St of a brake pedal, and the target deceleration Gst. It is a graph which shows the relationship between the weight (alpha) with respect to the last final target deceleration Gtf and the target deceleration Gpt. 7 is a flowchart showing a main part of a braking force control routine in Embodiment 2. 10 is a flowchart showing a main part of a braking force control routine in Embodiment 3. It is a graph which shows the example of the change of the restriction | limiting with respect to the increase rate of the target deceleration in Examples 1-3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Braking device 12 Brake pedal 14 Master cylinder 22FL-22RR Wheel cylinder 66, 68 Pressure sensor 24F, 24R, 26 Electromagnetic on-off valve 50FL-50RR Linear valve 60FL-60RR Linear valve 66, 68 Pressure sensor 70 Stroke sensor 72, 74FL-74RR Pressure sensor 76 Vehicle speed sensor 78 Electronic control unit

Claims (8)

  A vehicle braking force control device that obtains a target braking control amount based on a driver's braking operation amount and controls the braking force of each wheel based on the target braking control amount. The increase rate of the target braking control amount is limited to a first limit value or less over time, and when the predetermined time elapses, the increase rate of the target braking control amount is larger than the first limit value. A braking force control device for a vehicle, characterized by being limited to a limit value or less.   2. The vehicle braking force control apparatus according to claim 1, wherein at least the first limit value is variably set in accordance with the vehicle speed so as to be larger when the vehicle speed is high than when the vehicle speed is low.   3. The vehicle braking force control device according to claim 1, wherein the predetermined time is shorter when the vehicle speed is high than when the vehicle speed is low.   4. The vehicle braking force control device according to claim 1, wherein a restriction on an increase rate of the target braking control amount is made gentler than a restriction by the first restriction value at an initial stage of braking. 5.   After the driver's braking operation is started, the restriction on the increase rate of the target braking control amount is made gentler than the restriction by the first restriction value until the target braking control amount becomes equal to or greater than a restriction start reference value. The vehicle braking force control device according to claim 4.   Before the predetermined time elapses, the restriction on the increase rate of the target braking control amount is made gentler than the restriction by the first restriction value and more severe than the restriction by the second restriction value. The vehicle braking force control device according to any one of claims 1 to 5.   7. The vehicle braking force control device according to claim 1, wherein the target braking control amount is obtained as a target deceleration of the vehicle. 7. The vehicle control system according to claim 1, wherein a braking force of each wheel is controlled by controlling a corresponding braking pressure, and the target braking control amount is obtained as a target braking pressure of each wheel. Power control device.

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