JP2018118708A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device that is able to hinder a shock that may occur when a turbine rotation speed decreases lower than an engine rotational speed during deceleration travel.SOLUTION: If a turbine rotational speed Nt decreases lower than an engine rotational speed Ne during vehicle travel, brake master pressure Pbm is increased according to vehicle longitudinal acceleration G. Thereby, appropriate brake force corresponding to the brake master pressure Pbm of a brake master cylinder 38 is applied to a drive wheel 30. Accordingly, a shock, which may occur when the turbine rotational speed Nt decreases lower than the engine rotational speed Ne, can be hindered.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle control device that suppresses shocks that occur during vehicle deceleration.

  There has been proposed a vehicle control device having a function of stopping an engine when a predetermined engine stop condition is satisfied while the vehicle is running. This is the vehicle control apparatus disclosed in Patent Document 1. Patent Document 1 describes that a change in deceleration due to engine stop is suppressed by reducing a braking force applied from a brake when the engine is stopped.

JP 2014-40152 A Japanese Patent Laid-Open No. 2006-142246 JP 2008-163954 A

  By the way, when the turbine rotational speed falls below the engine rotational speed from the state where the turbine rotational speed of the fluid transmission device provided on the output side of the engine is higher than the engine rotational speed during the deceleration traveling before the engine stops, the vehicle Shock occurs due to the switching of the driving state.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to control a vehicle that can suppress a shock that occurs when the turbine rotational speed falls below the engine rotational speed during deceleration traveling. Is to provide.

  The gist of the first invention is: (a) a fluid transmission device including an engine, a pump impeller coupled to the engine, and a turbine impeller coupled to a drive wheel so as to be capable of transmitting power; And a braking device that generates a braking force according to the brake master pressure of the brake master cylinder, and is a vehicle control device that stops the engine when an engine stop condition is satisfied while the vehicle is running, and (b) deceleration When the turbine rotational speed of the turbine impeller falls below the engine rotational speed during traveling, the brake master pressure is increased in accordance with the amount of change in vehicle longitudinal acceleration.

  According to the vehicle control device of the first aspect of the present invention, when the turbine rotation speed falls below the engine rotation speed while the vehicle is running, the brake master pressure is increased in accordance with the amount of change in the vehicle longitudinal acceleration, so that it is suitable for the drive wheels. Since the braking force is applied, it is possible to suppress a shock that occurs when the turbine rotation speed falls below the engine rotation speed.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic block diagram which shows the basic composition of the vehicle which is one Example of this invention, and is the block diagram which showed the control system of the vehicle collectively. FIG. 2 is a flowchart for explaining a main part of a control operation of the electronic control device of FIG. 1, that is, a control operation for suppressing a shock that is generated when the driving state of the vehicle is switched during vehicle deceleration. It is an example of the time chart which shows the operation state when the control action based on the flowchart of FIG. 2 is performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a schematic configuration diagram showing a basic configuration of a vehicle 10 according to an embodiment of the present invention, and a block diagram showing a control system of the vehicle 10 together. The vehicle 10 includes an engine 20 that is an internal combustion engine as a driving force source for traveling. The output of the engine 20 is from a torque converter (T / C) 22 to a forward / reverse switching device 24 and a belt type continuously variable transmission 26. Is transmitted to the differential gear device 28 and distributed to the left and right drive wheels 30. The torque converter 22 corresponds to the fluid transmission device of the present invention.

  The forward / reverse switching device 24 is a power transmission switching device capable of switching between forward travel and reverse travel. The forward / reverse switching device 24 is mainly composed of a double pinion type planetary gear device having three rotating elements, for example, a sun gear, a ring gear, and a carrier. One of the sun gear and the carrier is connected to the torque converter 22, and the other is A forward clutch C1 is connected to the belt-type continuously variable transmission 26, and the two rotary elements are connected to rotate together, and a reverse brake B1 is fixed to the case or the like to stop rotating. Each of the forward clutch C1 and the reverse brake B1 is a single-plate or multi-plate hydraulic friction engagement device, the forward clutch C1 is a forward hydraulic friction engagement device, and the reverse brake B1 is a reverse hydraulic friction device. It is an engagement device. The belt-type continuously variable transmission 26 has a belt wound around a pair of variable pulleys with variable groove widths, and a gear ratio and a belt clamping force are respectively provided by hydraulic actuators (hydraulic cylinders) provided on the pair of variable pulleys. The pressure is controlled.

  The torque converter 22 includes a pump impeller 12 connected to the engine 20, a turbine impeller 14 connected to the forward / reverse switching device 24 (that is, connected to the drive wheel 30 so that power can be transmitted), and a one-way clutch 16. And a stator impeller 18 connected to a non-rotating member via the torque, and the rotation of the pump impeller 12 that rotates integrally with the engine 12 is transmitted to the turbine impeller 14 via the fluid. A fluid transmission device having an amplification function. A drive gear constituting the oil pump 40 is connected to the pump impeller 12, and the oil pump 40 is operated when the engine 12 rotates. Although not shown, a lock-up clutch is provided between the pump impeller 12 and the turbine impeller 14 to connect or disconnect them according to the traveling state.

  Hydraulic oil is supplied to the torque converter 22, the forward clutch C 1 and the reverse brake B 1 of the forward / reverse switching device 24, and the pair of hydraulic actuators of the belt-type continuously variable transmission 26 via a hydraulic control circuit 32. ing. The hydraulic control circuit 32 includes a valve body provided with an electromagnetic switching valve for switching an oil passage, an electromagnetic hydraulic control valve for controlling hydraulic pressure, and the like. The electromagnetic switching valve and the electromagnetic hydraulic control valve of the hydraulic control circuit 32 are provided. Is controlled, the forward / reverse switching device 24 and the belt-type continuously variable transmission 26 are controlled.

  For example, by controlling the forward clutch C1 constituting the forward / reverse switching device 24 to be engaged and the reverse brake B1 to be released, the forward travel mode capable of forward travel is established, and the forward clutch C1 is released. And a reverse travel mode capable of reverse travel is established by controlling to engage the reverse brake B1, and by controlling to release both the forward clutch C1 and the reverse brake B1, A neutral mode for interrupting power transmission is established. Further, the hydraulic pressure supplied to the pair of hydraulic actuators constituting the belt-type continuously variable transmission 26 is controlled via the hydraulic control circuit 32, so that the gear ratio is continuously changed and belt slip is suppressed. . Further, a part of the hydraulic oil supplied to the hydraulic control circuit 32 is used as lubricating oil, and the gears of the forward / reverse switching device 24, the belt pressing part of the belt type continuously variable transmission 26, the rotary bearing part, and the like are lubricated. The The hydraulic control circuit 32 is supplied with hydraulic oil discharged from the oil pump 40.

  The vehicle 10 includes a braking device 36 that applies a braking force according to the depression force of the brake pedal 34 by the driver to the drive wheels 30. The braking device 36 includes a brake pedal 34, a brake master cylinder 38 (hereinafter referred to as a master cylinder 38) that generates a brake master pressure Pbm corresponding to the depression force of the brake pedal 34, and a brake master cylinder 38 provided on the drive wheel 30. A brake main body 42 that generates a braking force proportional to the brake master pressure Pbm and a hydraulic pressure control unit 44 that can adjust the brake master pressure Pbm of the master cylinder 38 are included. The brake main body 42 is constituted by, for example, a disc brake or a drum brake. The hydraulic control unit 44 includes an electromagnetic hydraulic control valve and the like, and is configured to be able to increase and decrease the brake master pressure Pbm of the master cylinder 38 based on a hydraulic command signal from an electronic control unit 70 described later.

  When the brake pedal 34 is depressed by the driver in the braking device 36, a brake master pressure Pbm of the master cylinder 38 that is proportional to the depression force of the brake pedal 34 is generated. Further, the brake master pressure Pbm of the master cylinder 38 is supplied to the brake main body 42 to operate the brake main body 42, and a braking force proportional to the brake master pressure Pbm of the master cylinder 38 is applied to the drive wheels 30. . That is, the braking force applied to the drive wheel 30 increases as the depression force of the brake pedal 34 increases.

  Further, the vehicle 10 includes an electronic control unit 70 that includes at least one ECU as a controller that performs various controls. The electronic control unit 70 includes a microcomputer, and performs predetermined signal processing according to a program predetermined in the ROM while using a temporary storage function such as a RAM.

  The electronic control unit 70 is supplied with a shift operation signal Psh from a shift operation detection switch 84 that detects a shift operation of the shift lever 82, and is also detected by an engine rotation speed Ne detected by an engine rotation sensor and a turbine rotation sensor. The turbine rotation speed Nt, which is the rotation speed of the turbine impeller 14, the output rotation speed Nout corresponding to the vehicle speed V detected by the vehicle speed sensor, the accelerator operation amount Acc detected by the accelerator opening sensor, and the brake switch. Various information necessary for various controls, such as a brake operation (depression operation) Br and a signal representing the vehicle longitudinal acceleration G detected by the vehicle longitudinal acceleration sensor, is supplied.

  The shift lever 82 is disposed, for example, in the vicinity of the driver's seat, and is manually operated to at least the “D” position, the “R” position, the “P” position, and the “N” position. The D (drive) range for forward travel can be selected by the movement operation to, and the R (reverse) range for reverse travel can be selected by the movement operation to the “R” position. The “P” position is a position for selecting a P (parking) range for parking, and the “N” position is a position for selecting an N (neutral) range for interrupting power transmission.

  The electronic control unit 70 controls the output of the engine 20 in accordance with, for example, the accelerator operation amount Acc, and controls the hydraulic control circuit 32 in accordance with the range selection operation by the shift lever 82, thereby operating the forward / reverse switching device 24 in an operation mode. Switch. Specifically, the forward travel mode is set when the D range is selected by the shift lever 82, the reverse travel mode is selected when the R range is selected, and the neutral mode is selected when the P range or the N range is selected. Mode. That is, the operation mode of the forward / reverse switching device 24 is controlled by electrically switching the oil passage of the hydraulic control circuit 32 through an electromagnetic switching valve or the like according to the shift operation of the shift lever 82. Further, by controlling the hydraulic control circuit 32 according to the electronic control unit 70, the accelerator operation amount Acc, the vehicle speed V, etc., the gear ratio of the belt-type continuously variable transmission 26 is continuously changed and belt slippage occurs. The belt clamping pressure is controlled so as not to occur.

  The electronic control unit 70 functionally includes an idle stop control unit 72 that performs engine stop control for stopping the engine 20 when a predetermined engine stop condition is satisfied during traveling in the D range (including when the vehicle is stopped). ing. For example, when the vehicle speed V drops below a preset engine stop vehicle speed when the brake stop 34 is depressed and the brake speed is reduced and the vehicle speed V is set to the engine stop condition, the idle stop control unit 72 The engine 20 is disconnected from the power transmission path, and the fuel supply to the engine 20 is stopped to stop the engine 20.

  Further, when an engine start condition such as release of depression of the brake pedal 34 is satisfied while the engine 20 is stopped, the idle stop control unit 72 rotationally drives (cranks) the engine 20 with a starter motor (not shown). When the engine speed increases to a speed at which the engine 20 can operate independently, fuel supply to the engine 20 is started, and engine start control for starting the engine 20 by operating the ignition device is executed.

  By the way, in the belt type continuously variable transmission 26, the hydraulic pressure of the hydraulic oil supplied to the hydraulic actuator of the continuously variable transmission 26 decreases after the engine is stopped. The belt clamping pressure cannot be maintained with respect to the driving torque, and belt slipping may occur. In order to prevent the belt slip during the sudden braking, it is necessary to reduce the engine stop vehicle speed at which the stop control of the engine 20 is started to a speed at which the belt clamping pressure necessary for preventing the belt slip can be maintained. However, if the engine stop vehicle speed is too low, the turbine rotation speed Nt becomes lower than the engine rotation speed Ne during operation of the engine 20, and a shock is generated at this time. Specifically, in a state where the turbine rotational speed Nt is higher than the engine rotational speed Ne, the driven torque from the drive wheel 30 side is transmitted, but the turbine rotational speed Nt is reduced as the vehicle speed V decreases during traveling at a reduced speed. When the engine speed is lower than the engine rotation speed Ne, the driving torque from the engine 20 side is switched to a state where the driving torque is transmitted. Further, when the vehicle speed V decreases and falls below the engine stop vehicle speed, stop control of the engine 20 is started, the engine rotation speed Ne falls below the turbine rotation speed Nt, and the driven torque from the drive wheel 30 side is transmitted. A feeling of entrainment occurs by switching. A shock due to such switching of the driving state occurs.

  The electronic control unit 70 functionally includes an engine operation state determination unit 74 and a master pressure control unit 76 that execute a control operation for suppressing a shock caused by the switching of the drive state that occurs during the above-described deceleration traveling. Yes.

  The engine operating state determination unit 74 determines whether the engine 20 is operating or the engine 20 is stopped during the deceleration traveling. The operation of the engine 20 and the stop of the engine 20 are determined based on, for example, a command signal to the engine 20 output from the electronic control unit 70, an engine rotational speed Ne, or the like. Further, when it is determined that the engine 20 is in operation, the engine operation state determination unit 74 starts from the state where the turbine rotation speed Nt is higher than the engine rotation speed Ne (Nt> Ne). It is determined whether or not the state is switched to a state lower than the speed Ne (Nt ≦ Ne). In other words, the engine operating state determination unit 74 determines whether or not the vehicle 10 has been switched from the driven state to the driving state. Further, when it is determined that the turbine rotational speed Nt has been switched to the engine rotational speed Ne or lower, the engine operating state determination unit 74 determines whether or not the state (Nt ≦ Ne) continues.

  When it is determined that the turbine rotational speed Nt is lower than the engine rotational speed Ne, the master pressure control unit 76 controls the hydraulic control unit 44 of the master cylinder 38 to control the master cylinder according to the change amount ΔG of the vehicle longitudinal acceleration G. The brake master pressure Pbm of 38 is increased. The amount of change ΔG is the difference (G−Ga) between the vehicle longitudinal acceleration Ga and the vehicle longitudinal acceleration G detected at any time when the turbine rotational speed Nt falls below the engine rotational speed Ne. The master pressure control unit 76 stores, for example, a relationship map between the change amount ΔG (= G−Ga) and the pressure increase amount ΔPbm of the brake master pressure Pbm, and from the time when the turbine rotation speed Nt falls below the engine rotation speed Ne. A change amount ΔG is calculated as needed, and the calculated change amount ΔG is applied to the relationship map to determine a pressure increase amount ΔPbm of the brake master pressure Pbm, and the brake master pressure Pbm is increased by the pressure increase amount ΔPbm. Output. The relationship map is obtained and stored experimentally or in advance, and the vehicle longitudinal acceleration G is returned to the vehicle longitudinal acceleration Ga when the turbine rotational speed Nt is switched to the engine rotational speed Ne or lower. That is, the change amount ΔG is set to a value that becomes zero due to deceleration by increasing the brake master pressure Pbm. Specifically, the relationship map is such that the pressure increase amount Pbm increases in proportion to the change amount ΔG. From this, when the turbine rotational speed Nt is switched to the engine rotational speed Ne or lower during traveling at a reduced speed, the brake master pressure Pbm is increased by the determined pressure increase amount ΔPbm, so that an appropriate braking force is applied to the drive wheels 30. And the pop-out feeling that occurs when the turbine rotational speed Nt falls below the engine rotational speed Ne is suppressed.

  Further, in the transition period in which the master pressure control unit 76 increases the brake master pressure Pbm, the engine operation state determination unit 74 determines whether or not the state in which the turbine rotation speed Nt is lower than the engine rotation speed Ne continues. While this state continues, the master pressure control unit 76 continuously increases the brake master pressure Pbm. On the other hand, the engine operating state determination unit 74 determines that the state where the turbine rotational speed Nt is lower than the engine rotational speed Ne is not continued (that is, determines that the engine rotational speed Ne is lower than the turbine rotational speed Nt), or When it is determined that the engine 20 has stopped, the master pressure control unit 76 stops increasing the brake master pressure Pbm and returns it to the normal brake master pressure Pbm.

  FIG. 2 is a flowchart for explaining a main part of the control operation of the electronic control unit 70, that is, a control operation for suppressing a shock that occurs when the driving state of the vehicle 10 is switched while the vehicle is decelerating. This flowchart is executed during vehicle deceleration traveling.

  In step S1 (hereinafter, step is omitted) corresponding to the control operation of the engine operation state determination unit 74, it is determined whether or not the engine 20 is in operation. If S1 is negative, the routine is terminated. On the other hand, when S1 is affirmed, in S2 corresponding to the control operation of the engine operation state determination unit 74, the turbine rotation speed Nt is lower than the engine rotation speed Ne from the state where the turbine rotation speed Nt is higher than the engine rotation speed Ne. It is determined whether or not the state has changed. If S2 is negative, the routine is terminated. When S2 is affirmed, it is determined that the magnitude relationship between the turbine rotational speed Nt and the engine rotational speed Ne is reversed before the engine is stopped, that is, the vehicle 10 is switched from the driven state to the driven state, and the master pressure control unit In S3 corresponding to the control function 76, the brake master pressure Pbm of the master cylinder 38 is increased in accordance with the change in the vehicle longitudinal acceleration G. In S4 corresponding to the control operation of the engine operating state determination unit 74, it is determined whether or not the engine 20 has stopped. When S4 is denied, it is determined whether or not the state where the turbine rotational speed Nt is lower than the engine rotational speed Ne continues. When S4 is affirmed, the process returns to S3 and the brake master pressure Pbm is continuously increased. When S4 is affirmed (engine stop) and when S6 is negative, the increase of the brake master pressure Pbm is stopped in S5 corresponding to the control operation of the master pressure control unit 76.

  FIG. 3 is an example of a time chart showing an operation state when the control operation based on the flowchart of FIG. 2 is executed, and shows an aspect when the vehicle is stopped. In FIG. 3, a time point t1 corresponds to a time point when the turbine rotational speed Nt falls below the engine rotational speed Ne, and a time point t2 corresponds to a time point when the engine rotational speed Ne falls below the turbine rotational speed Nt again.

  Before the time t1, the vehicle 10 is decelerating when the brake pedal 34 is depressed, and the turbine rotational speed Nt is reduced accordingly. At this time, the vehicle 10 is in a driven state in which driven torque is transmitted from the driving wheel 30 side. When the turbine rotational speed Nt falls below the engine rotational speed Ne at time t1, that is, when the vehicle 10 is switched from the driven state to the driving state, the brake master pressure Pbm is increased. In relation to this, the change in the vehicle longitudinal acceleration G is suppressed as indicated by the solid line, and the occurrence of a pop-out feeling is suppressed. On the other hand, when the brake master pressure Pbm is not increased, the vehicle longitudinal acceleration G changes as shown by the broken line, and a feeling of jumping out occurs. When the engine stop condition of the engine 20 is satisfied in the vicinity of the time point t2, the fuel supply to the engine 20 is stopped, and the engine speed Ne is decreased. When the engine rotational speed Ne falls below the turbine rotational speed Nt at time t2, the increase in the brake master pressure Pbm is stopped. At time t2, the engine rotational speed Ne is switched to the turbine rotational speed Nt or less, so that the vehicle 10 switches from the driven state to the driven state again, and a slight pull-in feeling occurs, but the brake master pressure Pbm indicated by the broken line increases. Compared with the case where it is not performed, the amount of change in the vehicle longitudinal acceleration G is reduced, and the pull-in feeling is reduced. Thus, since the brake master pressure Pbm is increased, the feeling of popping out and the feeling of pulling in that occur during deceleration traveling is suppressed, so that the shock of the vehicle 10 during deceleration traveling is suppressed.

  As described above, according to the present embodiment, when the turbine rotational speed Nt falls below the engine rotational speed Ne during traveling of the vehicle, driving is performed by increasing the brake master pressure Pbm according to the amount of change in the vehicle longitudinal acceleration G. Since an appropriate braking force is applied to the wheel 30, it is possible to suppress a shock that occurs when the turbine rotational speed Nt falls below the engine rotational speed Ne.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the torque converter 22 having the torque amplification function is provided between the engine 20 and the forward / reverse switching device 24. However, even if the fluid transmission device does not have the torque amplification function, I do not care.

  Further, in the above-described embodiment, the vehicle 10 is configured by including the forward / reverse switching device 24 and the belt-type continuously variable transmission 26 in series between the torque converter 22 and the drive wheels 30. Is not limited to this. For example, a mechanism that can transmit the torque output from the torque converter 22 to the drive wheels 30 such as one having a stepped automatic transmission between the torque converter 22 and the drive wheels 30 may be changed as appropriate. it can.

  Further, in the above-described embodiment, the master pressure control unit 76 is calculated from time to time in a relational map composed of the change amount ΔG of the longitudinal acceleration G and the increase amount ΔPbm of the brake master pressure Pbm that are obtained and stored in advance. The amount of increase ΔPbm of the brake master pressure Pbm is calculated by applying the change amount ΔG of the longitudinal vehicle acceleration G. However, the vehicle longitudinal acceleration G and the turbine rotational speed Nt are less than the engine rotational speed Ne. The pressure increase amount ΔPbm of the brake master pressure Pbm may be calculated based on a feedback control control expression in which the change amount ΔG (= G−Ga) with respect to the vehicle longitudinal acceleration Ga at the time is a deviation.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

10: Vehicle 20: Engine 12: Pump impeller 14: Turbine impeller 22: Torque converter (fluid transmission)
30: Drive wheel 36: Braking device 38: Brake master cylinder 70: Electronic control device (control device)

Claims (1)

An engine, a fluid transmission device including a pump impeller coupled to the engine and a turbine impeller coupled to a drive wheel so that power can be transmitted, and a braking force corresponding to a brake master pressure of a brake master cylinder A control device for a vehicle that stops the engine when an engine stop condition is satisfied while the vehicle is running.
The vehicle control device, wherein the brake master pressure is increased in accordance with the amount of change in vehicle longitudinal acceleration when the turbine rotational speed of the turbine impeller drops below the engine rotational speed during traveling at a reduced speed.

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