JP2019044883A - Shift controller - Google Patents

Abstract

To reduce concerns that a brake fading phenomenon may occur.SOLUTION: An engine ECU 76 provided in a vehicle 10 is configured to, when a specific condition containing a travel condition that the vehicle 10 is traveling on a downhill of a mountain part, and a brake condition that an operating ratio of a brake mechanism 46 goes beyond a threshold is established, switch a shift diagram referred to by a CVT_ECU to a shift diagram corresponding to low gear side setting. The engine ECU 76 is also configured to, when the specific condition is not established, switch the transmission diagram referred to by the CVT_ECU to a standard shift diagram (=shift diagram corresponding to normal setting).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transmission control device, and more particularly to a transmission control device that controls setting of a transmission provided in a vehicle.

  An example of this type of shift control device is disclosed in Patent Document 1. According to this document, different gradient coefficients are set according to on / off of the brake switch, and different shift maps are selected according to the magnitude relationship between the set gradient coefficient and the threshold value. The shift process is performed with reference to the selected shift map, whereby a shift characteristic suitable for the gradient is obtained.

JP 2003-194203 A

  When traveling downhill on a mountain road, the engine brake should be heavily used to avoid a brake fade phenomenon. However, in Patent Document 1, a vehicle is traveling downhill on a mountain road when selecting a shift map. It is not judged whether or not. As a result, in Patent Document 1, there is a possibility that a brake fade phenomenon may occur while traveling downhill on a mountain road.

  Therefore, a main object of the present invention is to provide a speed change control device that can reduce the fear of occurrence of a brake fade phenomenon.

  A speed change control device according to the present invention is a speed change control device for controlling a setting of a transmission provided in a vehicle having a brake mechanism, wherein the vehicle is traveling on a downhill on a mountain road and the brake mechanism. The first switching means for switching the transmission setting to the low gear side setting when a specific condition including a braking condition that the operating ratio exceeds the threshold is satisfied, and the transmission setting is normally set when the specific condition is not satisfied The second switching means for switching to the setting is provided.

  By switching the transmission setting to the low gear setting when the specific condition is satisfied, so-called engine braking is exhibited even without a shifting operation. As a result, the operating ratio of the brake mechanism is reduced, and the concern that the brake fade phenomenon occurs is reduced. Further, since the engine brake is exhibited, stable and safe curve traveling is possible, and further, the actual fuel consumption can be improved by increasing the engine speed, that is, increasing the regenerative power generation amount.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a block diagram which shows a part of principal part structure of the vehicle of this Example. It is a block diagram which shows the other part of principal part structure of the vehicle of this Example. FIG. 3 is an illustrative view showing one example of a shift map referred to by the CVT_ECU shown in FIG. 2. It is a flowchart which shows a part of operation | movement of engine ECU shown in FIG. It is an illustration figure which shows an example of the shift map referred by the vehicle of another Example.

  Referring to FIGS. 1 and 2, vehicle 10 of this embodiment includes a four-stroke engine (internal combustion engine) 12 having three cylinders 141 to 143 as a power source. The intake pipe 32 branches into three at positions upstream of the cylinders 141 to 143. On the other hand, the exhaust pipes 36 are collected from three to one at positions downstream of the cylinders 141 to 143. The combustion chamber 16 provided in each of the cylinders 141 to 143 communicates with the intake pipe 32 via the intake valve 18 and communicates with the exhaust pipe 36 via the exhaust valve 20.

  A surge tank 44 for leveling the air flow rate is provided at the branch point of the intake pipe 32. Further, an air cleaner 34 for separating dust from the atmosphere and a single throttle valve 38 whose opening degree is adjusted by a valve motor 42 are provided at a position upstream of the surge tank 44.

  Further, a fuel injection device 40 assigned to each of the cylinders 141 to 143 for injecting fuel into the intake pipe 32 is provided at a position downstream of the surge tank 44. On the other hand, a muffler 64 having a catalyst 62 is provided at a position downstream of the aggregation point of the exhaust pipe 36.

  When an IG on operation is performed by an ignition key (not shown), the engine ECU 76 turns on the relay 84 shown in FIG. 2 to start the engine 12. The electric power of the battery 88 is supplied to the starter 86 through the relay 84 in the on state, and the starter 86 performs cranking by the electric power of the battery 88. As a result, the engine 12 is started.

  When the engine 12 is started, the engine ECU 76 adjusts the opening degree of the throttle valve 38 through the valve motor 42 so that the idle state is maintained. The amount of intake air that has passed through the air cleaner 34 is defined by a throttle valve 38, and the fuel injection amount of the fuel injection device 40 is adjusted so that an air-fuel mixture that shows the stoichiometric air-fuel ratio is generated.

  When the accelerator pedal 66 is depressed in this state, the engine ECU 76 drives the valve motor 42. The throttle valve 38 is opened by a valve motor 42, whereby the intake air amount and the fuel injection amount of the fuel injection device 40 increase while maintaining the theoretical air-fuel ratio.

  The air-fuel mixture is supplied to the combustion chamber 16 when the intake valve 18 is opened. The supplied air-fuel mixture is ignited by the spark plug 30 immediately before the piston 22 connected to the crankshaft 26 via the connecting rod 24 reaches the top dead center. The piston 22 moves up and down by the explosion of the air-fuel mixture, whereby the crankshaft 26 rotates.

  The air after burning the air-fuel mixture, that is, the combustion gas, is discharged from the combustion chamber 16 when the exhaust valve 20 is opened, and is supplied to the muffler 64 through the exhaust pipe 36. The catalyst 62 oxidizes and reduces carbon monoxide, hydrocarbons, and nitrogen oxides contained in the combustion gas to generate water, carbon dioxide, and nitrogen. From the vehicle 10, the gas thus purified is discharged.

  A flywheel 28 is attached to the crankshaft 26, and fluctuations in the rotational speed of the crankshaft 26, that is, the rotational speed of the engine 12 are suppressed by the flywheel 28. Further, the rotational speed of the engine 12 is detected by the engine rotation sensor 60. The acceleration sensor 68 detects the acceleration of the vehicle 10 based on the detection result of the engine rotation sensor 60 and gives the detection result to the engine ECU 76.

  The rotational force of the crankshaft 26 is transmitted to a drive shaft (not shown) via the CVT 78 shown in FIG. The gear ratio of the CVT 78 is adjusted by the CVT_ECU 90. For this adjustment, the shift diagram shown in FIG. 3 stored in the memory 90m is referred to.

  According to FIG. 3, the shift diagram shows different shift lines according to the opening degree (= TTL) of the throttle valve 38. The CVT_ECU 90 selects a shift line corresponding to the current opening of the throttle valve 38, detects the travel speed of the vehicle 10 corresponding to the rotational speed of the engine 12 on the selected shift line, and obtains the detected travel speed. Adjust the gear ratio as follows. As a result, vehicle 10 travels at a speed according to the gear ratio set in CVT 78.

  In this embodiment, the shift diagram indicated by the solid line is a standard shift diagram (= shift diagram corresponding to the normal setting), and the reference shift diagram is referred to when a specific condition described later is not satisfied. To control the gear ratio. On the other hand, when the specific condition is satisfied, the shift diagram to be referred to for the gear ratio control is switched to a shift diagram corresponding to the setting on the low gear side as indicated by the broken line.

  The rotational force of the crankshaft 26 is also transmitted to the rotating shaft 82s of the alternator 82 via the belt 80. The rotational force of the rotating shaft 82s is converted into electric power, and the converted electric power is stored in the battery 88.

  When the brake pedal 52 constituting the brake mechanism 46 is depressed, the brake depression force is transmitted to a brake pad (not shown) via the brake booster 50. The brake pad sandwiches a disk (not shown), and the vehicle speed is reduced by the frictional force between the brake pad and the disk.

  The negative pressure chamber of the brake booster 50 communicates with the intake pipe 32 via the check valve 48, and the brake booster 50 has a intake manifold negative pressure (negative pressure generated in the intake pipe 32) or a booster negative pressure (generated in the negative pressure chamber). The difference between the negative pressure) and the atmospheric pressure is used to assist the driver's braking force. Therefore, the vehicle 10 quickly decelerates with a small brake depression force.

  A brake switch 54 and a brake stroke sensor 56 are provided in the vicinity of the brake pedal 52, and a brake fluid pressure sensor 58 is provided in the brake booster 50. The brake switch 54 is turned on when the brake pedal 52 is depressed, and is turned off when the depression of the brake pedal 52 is released.

  The brake stroke sensor 56 detects the depression amount of the brake pedal 52, and the brake fluid pressure sensor 58 detects the pressure of the brake oil filled in the brake booster 50. The on / off state of the brake switch 54, the detection result of the brake stroke sensor 56, and the detection result of the brake hydraulic pressure sensor 58 are all supplied to the engine ECU 76.

  If the brake pedal 52 is continuously depressed while traveling down a mountain road with the CVT 78 set to the “D range”, a brake fade phenomenon may occur, and the frictional force between the brake pad and the disc may be reduced. Therefore, in this embodiment, in order to reduce the concern that the brake fade phenomenon will occur, the shift diagram control according to the flowchart shown in FIG. 4 is repeatedly executed by the engine ECU 76.

  Note that when executing shift map control, a tilt angle sensor 70 that detects the tilt angle of the vehicle 10, a steering angle sensor 72 that detects the steering angle of the vehicle 10, and a GPS device 74 that detects the current position of the vehicle 10. Each output of is additionally referenced. A control program corresponding to the flowchart shown in FIG. 4 is stored in the memory 76m.

  In step S <b> 1, it is determined whether the current position is a mountain road based on the detection result of the steering angle sensor 72 and the output of the GPS device 74. In step S3, it is determined whether or not the vehicle 10 is traveling downhill based on the depression force of the accelerator pedal 66, the detection result of the acceleration sensor 68, and the detection result of the inclination angle sensor 70.

  In step S5, whether or not the operating ratio of the brake mechanism 46 (= the ratio of the time during which the brake pad has sandwiched the disc in the most recent one minute) exceeds the threshold value TH, whether the brake switch 54 is on / off, The determination is made based on the detection result of the stroke sensor 56 and the detection result of the brake fluid pressure sensor 58.

  As described above, steps S1 and S3 are for determining whether or not the traveling condition that the vehicle 10 is traveling on a downhill on a mountain road is satisfied. In step S5, the operating ratio of the brake mechanism 46 is determined. It is determined whether or not a brake condition of exceeding the threshold value is satisfied. The specific condition corresponds to a condition including such a travel condition and a brake condition, and steps S1 to S5 correspond to steps for determining whether or not the specific condition is satisfied.

  If at least one of the determination result of step S1, the determination result of step S3, and the determination result of step S5 is NO, it is considered that the specific condition is not satisfied, and the process proceeds to step S7. In step S7, the shift map referred to by the CVT_ECU 90 is switched to the standard shift map. When switching is completed, the routine returns to the upper hierarchy.

  On the other hand, if any of the determination result of step S1, the determination result of step S3, and the determination result of step S5 is YES, it is considered that the specific condition is satisfied, and the process proceeds to step S9. In step S9, it is determined whether or not the currently selected shift map is a standard shift map. If the determination result is YES, the process proceeds directly to step S13. If the determination result is NO, step S11 is performed. The process proceeds to step S13 after waiting for a predetermined time.

  In step S13, the shift diagram referred to by the CVT_ECU 90 is switched to a shift diagram corresponding to the setting on the low gear side. As a result, the engine brake is more effective. When the change of the shift diagram is completed, the routine returns to the upper hierarchy routine.

  As can be seen from the above description, the engine ECU 76 provided in the vehicle 10 has a traveling condition that the vehicle 10 is traveling on a downhill on a mountain road, and a braking condition that the operating ratio of the brake mechanism 46 exceeds the threshold value TH. When the specific condition including is established, the shift diagram referred to by the CVT_ECU 90 is switched to the shift diagram corresponding to the setting on the low gear side (S13). The engine ECU 76 also switches the shift diagram referred to by the CVT_ECU 90 to the standard shift diagram (= shift diagram corresponding to the normal setting) when the specific condition is not satisfied (S7).

  By selecting a shift diagram corresponding to the setting on the low gear side when the specific condition is satisfied, the engine brake is exhibited even without the shift operation of the CVT 78. As a result, the operating ratio of the brake mechanism 46 decreases, and the concern that the brake fade phenomenon may occur and the life of the brake pad may be shortened. Also, the use of engine braking enables stable and safe curve traveling, and further improves the actual fuel consumption by increasing the engine speed, that is, increasing the amount of regenerative power generation.

  In this embodiment, the CVT 78 is mounted on the vehicle 10, but an AT may be mounted instead of the CVT 78. In this case, AT_ECT for controlling AT refers to the shift diagram shown in FIG. 5 instead of the shift diagram shown in FIG.

  In FIG. 5, a shift diagram indicated by a solid line corresponds to a standard shift diagram, and a shift diagram indicated by a broken line corresponds to a shift diagram corresponding to the setting on the low gear side. Further, the gear ratio at the time of shift down is adjusted along a gear shift diagram indicated by a thick line (solid line or broken line), and the gear ratio at the time of shift up is adjusted according to a gear shift diagram indicated by a thin line (solid line or broken line). .

DESCRIPTION OF SYMBOLS 10 ... Vehicle 12 ... Engine 16 ... Combustion chamber 46 ... Brake mechanism 68 ... Acceleration sensor 70 ... Inclination angle sensor 72 ... Steering angle sensor 74 ... GPS device 76 ... Engine ECU
78 ... CVT

Claims (1)

A shift control device that controls setting of a transmission provided in a vehicle including a brake mechanism,
When a specific condition including a running condition that the vehicle is traveling on a downhill on a mountain road and a brake condition that the operation ratio of the brake mechanism exceeds a threshold value is satisfied, the setting of the transmission is set to the low gear side setting. A shift control apparatus comprising: a first switching unit that switches; and a second switching unit that switches the setting of the transmission to a normal setting when the specific condition is not satisfied.

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