JP4415309B2 - Automatic transmission control device - Google Patents

Description

  The present invention relates to an automatic transmission control apparatus that performs transmission control to a gear stage that minimizes a fuel consumption rate while preventing a vehicle from stalling.

  As an automatic shift control device for a transmission for a vehicle, a shift control referred to as a low fuel consumption mode for shifting the gear stage of the transmission to a gear stage having the smallest fuel consumption rate within a range in which the vehicle does not stall is executed. Have been proposed (for example, Patent Documents 1 and 2, etc.), and the present inventor has developed the following automatic shift control device of this type.

  As shown in FIG. 5, this automatic transmission control device uses a constant fuel consumption map A, a maximum torque diagram B, and a constant horsepower diagram C of the engine, and a gear that has the smallest fuel consumption rate while preventing vehicle stall. Shift control is performed in stages. In the figure, the horizontal axis represents the engine speed (rpm), and the vertical axis represents the net average effective pressure Pme corresponding to torque. The equal fuel consumption map A means that the fuel consumption rate SFC is the same if it is on the same line, and the fuel consumption improves as it approaches the inner line, and conversely, the fuel consumption deteriorates as it approaches the outer line. The maximum torque diagram B shows the maximum torque that the engine exerts when the accelerator pedal is fully opened.

  The equal horsepower diagram C obtains the minimum necessary torque for maintaining the current driving state of the vehicle, that is, for steady running in the current state, based on the torque currently generated by the engine. The required horsepower is obtained by multiplying the required torque by the current engine speed, and is created based on this required horsepower. Specifically, after obtaining the required horsepower, the engine speed at each gear stage relative to the current gear stage is calculated based on the gear ratio of each gear stage, and the required horsepower is calculated at each gear stage. To obtain the required torque at each gear stage, and connect the plot points of the required torque at each gear stage and the engine rotation speed to obtain the equihorsepower diagram C.

  Then, among the gear stages on the equi-horsepower diagram C, only the gear stage whose required torque after the shift is equal to or less than the maximum torque is selected as a gear stage that can be shifted. This is because if the required torque after the shift is larger than the maximum torque, the vehicle will stall after the shift. Then, the gear stage having the smallest fuel consumption rate among the selected gear stages is specified as the target gear stage, and the gear is shifted to this gear stage. As a result, the gear is shifted to the smallest gear speed within a range where the vehicle does not stall.

  In the illustrated example, N, N-1, and N-2 stages are selected as gear stages that can be shifted, and among these, the N stage having the lowest fuel consumption rate is specified, and the speed is changed to the N stage.

Japanese Patent Publication No. 5-14133 No. 7-16924

  By the way, in the low fuel consumption mode, since the shift control is performed to the gear stage having the best fuel efficiency while maintaining the vehicle speed, when the vehicle is slightly stalled while climbing a gentle slope, Even in a situation where the vehicle speed can be recovered without shifting by increasing the number of pedals, depending on the shape of the equal fuel consumption map A, a downshift is forcibly performed to maintain the vehicle speed. This phenomenon tends to occur when the vehicle is temporarily stalled (during deceleration) when attempting to accelerate or decelerate the vehicle speed with the accelerator pedal after shifting on an uphill road.

  The shift down will be described with reference to FIG. When the vehicle stalls with the current output torque at the current gear stage (N stage) while traveling on an uphill road, the low fuel consumption mode is controlled so as not to stall the vehicle on condition that the accelerator pedal is on. Therefore, a shortage torque T ′ for stopping the stall and maintaining the vehicle speed is calculated. Then, the insufficient torque T ′ is added to the current output torque T, and an equal horsepower diagram C ′ is drawn with the value (T + T ′). Then, on the diagram C ′, the gear stage (N−1 stage), which is one stage lower than the current gear stage (N stage), has a smaller fuel consumption rate, so the gear shifts down from the N stage to the N−1 stage. The vehicle speed is maintained.

  However, if such control is performed at the time of the temporary vehicle stall described above, a downshift is forcibly performed each time, and thus the drive feeling (shift feeling) is deteriorated. In addition, if the above control is performed when the driver attempts to decelerate a vehicle traveling on an uphill road by adjusting the depression / depression of the accelerator pedal, the vehicle speed is maintained as the vehicle is downshifted. The driver's intention to slow down will not be reflected, and drive feeling will deteriorate.

  An object of the present invention is to prohibit a downshift that deteriorates the drive feeling when the vehicle is decelerated.

In order to achieve the above object, an automatic shift control device according to a first aspect of the present invention includes a shift control means for shifting to a gear stage at which the fuel consumption rate is determined to be the smallest within a range where the vehicle does not stall, and the shift control means. and a shift prohibition means for prohibiting the shift, when detecting a deceleration of the vehicle accelerator pedal is on, the necessary torque required to maintain the current vehicle speed to stop the deceleration, is currently output when an automatic transmission control device which Ru determined by adding the shortage of the torque for preventing the vehicle is decelerated to the torque, upon actuation of the shift control means, the required torque is smaller than the maximum torque at the current engine rotational speed, the shifting operates the prohibiting means prohibits the shift by the shift control means, when the required torque is equal to or greater than the maximum torque at the current engine rotational speed, to said shift control means And it performs a shift down.

  An automatic shift control device according to a second aspect of the present invention includes a shift control means that shifts to a gear stage at which the fuel consumption rate is determined to be the smallest within a range in which the vehicle does not stall, and stops deceleration when detecting deceleration of the vehicle. When the required torque required to maintain the current vehicle speed is obtained by adding the insufficient torque to prevent the vehicle from decelerating to the currently output torque, and this required torque is smaller than the maximum torque at the current engine speed And a gear shift prohibiting means for virtually replacing the fuel consumption rate of the current gear stage with a minimum value and holding the current gear stage by the shift control means.

  According to the present invention, when the vehicle is decelerated, it is possible to prohibit a downshift that deteriorates the drive feeling.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram of an automatic transmission control device for a vehicle according to the present embodiment.

  The automatic transmission control device of this embodiment performs automatic transmission control of a multi-stage transmission 3 (here, a forward 12-stage transmission) connected to a diesel engine 1 via a clutch 2.

  The engine 1 is controlled by an engine control means (ECU) 6. The ECU 6 basically determines the actual engine rotation speed and accelerator opening (from the outputs of the engine rotation sensor 7 that detects the rotation speed rpm of the engine 1 and the accelerator opening sensor 8 that detects the opening of the accelerator pedal 5. Engine load) is read, and the fuel injection amount and fuel injection timing (engine output) are controlled mainly based on these.

  The clutch 2 and the transmission 3 are automatically controlled by a TMCU (basic control means) 9. The ECU 6 and the TMCU 9 are connected to each other via a bus cable or the like and can communicate with each other.

  The clutch 2 is provided with a clutch actuator 10, and the TMCU 9 outputs a signal to the clutch actuator 10 to control connection / disconnection of the clutch 2 via the clutch actuator 10. In this embodiment, the clutch 2 can be manually connected / disconnected by the clutch pedal 11.

  Further, the transmission 3 is provided with a gear shift unit (GSU) 12, and the TMCU 9 outputs a signal to the GSU 12 and controls the transmission 3 through the GSU 12. The transmission 3 is provided with a gear position sensor 23 for detecting the gear position, and the detection value of the gear position sensor 23 is transmitted to the TMCU 9.

  When shifting the transmission 3, the TMCU 9 first outputs a signal to the clutch actuator 10 to disengage the clutch 2, and then outputs a signal to the GSU 12 to execute a shifting operation (gear release, gear in) of the transmission 3. When the shifting operation is completed, the clutch 2 is connected. In the present embodiment, the transmission 3 can also be manually shifted by the shift change means 29.

  The TMCU 9 is a component that characterizes the present embodiment, and includes a shift control means 9a and a shift prohibiting means 9b that operate in the low fuel consumption mode.

  The shift control means 9a shifts to a gear stage that is determined to have the lowest fuel consumption rate while maintaining the current driving state of the vehicle, that is, within a range where the vehicle does not stall. Since the shift control by the shift control means 9a is the same as that described above with reference to FIG. 5, the detailed description is omitted, but the outline is as follows.

  That is, using the equal fuel consumption map A, the maximum torque diagram B, and the equal horsepower diagram C shown in FIG. 5, the gears on the equal horsepower diagram C that have a maximum torque larger than the required torque are selected. Among these, the gear stage having the smallest fuel consumption rate is specified as the target gear stage, and the speed is changed to the target gear stage. As a result, the speed is changed to a gear position where the fuel consumption rate is minimized within a range in which the vehicle does not stall.

  The shift prohibiting means 9b shows the necessary torque required to stop the deceleration and maintain the current vehicle speed when a vehicle speed sensor or the like provided on the output shaft of the transmission 3 is detected. Thus, when the required torque (T + T ′) is smaller than the maximum torque Tm at the current engine speed, the shift is prohibited. Shifting by means 9a is prohibited.

  According to the shift control unit 9a and the shift prohibiting unit 9b, on a normal flat road, the shift control unit 9a performs shift control to a gear stage having the best fuel consumption within a range where the current vehicle speed is maintained and the vehicle is not stalled. In a situation where the vehicle stalls on a gentle uphill road or the like, gear shifting is prohibited if the necessary torque (T + T ′) necessary to maintain the vehicle speed is smaller than the maximum torque Tm at the current engine speed. It is possible to prohibit a downshift that deteriorates the drive feeling when the vehicle is decelerated.

  That is, if there is no shift prohibiting means 9b, as shown in FIG. 6, the gear stage on the lower speed side than the current gear stage on the constant horsepower diagram C ′ drawn based on the required torque (T + T ′) as shown in FIG. Since the fuel consumption rate is lower, the vehicle speed is maintained by shifting down by one step, but this shift down and maintaining the vehicle speed is when the vehicle speed is constant or subtly accelerated or decelerated with the accelerator pedal after shifting on the uphill road If this is done during a temporary vehicle stall, drive feeling will be worsened.

  In this embodiment, since the shift prohibiting means 9b is provided, when the vehicle stalls, if the vehicle speed can be recovered by stepping on the accelerator pedal (required torque (T + T ′) is smaller than the maximum torque Tm), Shift down is prohibited. Therefore, frequent downshifts can be prevented, and the vehicle speed can be adjusted according to the driver's intention (accelerator pedal depression), thereby improving drive feeling.

  The shift control by the shift control means 9a and the shift prohibiting means 9b in the low fuel consumption mode will be described with reference to FIGS.

  FIG. 2 is a flowchart for determining a gear to be shifted.

  In step S1, whether or not the vehicle is decelerating is determined by a vehicle speed sensor or the like provided on the output shaft of the transmission 3. If NO, that is, if the vehicle is accelerating or traveling at a constant speed, the process proceeds to step S2, and the gear stage to be shifted is set from the current gear stage to the highest gear stage, and the gear stage to be shifted up is selected. If yes, that is, if the vehicle is decelerating, the process proceeds to step S3, where the gear stage to be shifted is set from the start gear stage to the current gear stage, and the gear stage to be shifted down is selected.

  FIG. 3 is a flowchart for determining a flag for operating the shift prohibiting means 9b.

  In step S11, it is determined whether or not the vehicle is decelerating (stall). If no, that is, if the vehicle is accelerating or traveling at a constant speed, the driving force of the vehicle has overcome or balanced the running resistance on the uphill road, etc., so a downshift is necessary to maintain the vehicle speed. Absent. Therefore, the flag is turned off toward step S15.

  If yes, that is, if the vehicle is decelerating, the running resistance due to the uphill road etc. is greater than the driving force of the vehicle and the vehicle is stalled, so a downshift is required to maintain the vehicle speed. . In this case, the process proceeds to step S12.

  In step S12, the necessary torque required to stop the vehicle deceleration (stall) and maintain the current vehicle speed is added to the current output torque T that is currently output, and the stall torque T 'for recovering the stall. To calculate.

  In step S13, it is determined whether the required torque (T + T ') is less than the maximum torque Tm of the current engine speed. If yes, that is, if the required torque (T + T ′) is less than the maximum torque Tm, the vehicle stall can be recovered by depressing the accelerator pedal. Therefore, the flag is turned on in step S14, and the operation of the shift prohibiting means 9b is permitted. The Then, the shift control by the shift control means 9a is prohibited and the vehicle is operated with the current gear stage.

  If NO in step S13, that is, if the required torque (T + T ') is equal to or greater than the maximum torque Tm, the vehicle stall cannot be recovered even if the accelerator pedal is depressed, so the process proceeds to step S15, the flag is turned off, and the shift prohibiting means 9b Operation is prohibited. Then, the shift control means 9a shifts to a gear stage having the smallest fuel consumption rate within a range where the vehicle does not stall.

  FIG. 4 is a flowchart for determining the target gear stage.

  In step S21, the fuel consumption rate at the shift target gear determined in steps S2 and S3 of FIG. 2 is determined. In step S22, it is determined whether the flag is on. If yes, that is, if the operation of the shift prohibiting means 9b is permitted, the process proceeds to step S23, where the fuel consumption rate at the current gear stage is virtually minimized. In step S24, it is determined whether there are a plurality of gear stages at which the fuel consumption rate is minimized. Since the fuel consumption rate of the current gear stage is set to the minimum value in step S23, the result in step S24 is no and the process proceeds to step S26. In step S26, the target gear stage is set to the gear stage with the minimum fuel consumption rate, that is, the current gear stage in which the fuel consumption is minimized in step S23. Therefore, no shift is made from the current gear stage.

  Thus, when step S22 is YES, the operation of the shift prohibiting means 9b is permitted, and the vehicle speed can be recovered by depressing the accelerator pedal when the vehicle stalls on a gentle uphill or the like (the required torque is smaller than the maximum torque). Situation), downshifting is prohibited. Therefore, frequent downshifts can be prevented, and the vehicle speed can be adjusted according to the driver's intention (accelerator pedal depression), thereby improving drive feeling. In FIG. 4, steps S22, S23, S24 and S26 constitute the shift prohibiting means 9b.

  If NO in step S22, that is, if the flag is OFF, the process bypasses step S23 and proceeds to step S24. Then, it is determined whether there are a plurality of gear stages at which the fuel consumption rate is minimum. If yes, the process proceeds to step S25, and among the gear stages having the minimum fuel consumption, the fastest gear stage is set as the target gear stage. The process proceeds to step S26, and the gear stage with the minimum fuel consumption is set as the target gear stage.

  As described above, when NO in step S22, step S23 which minimizes the fuel consumption at the current gear stage is bypassed, so that the operation of the shift prohibiting means 9b is prohibited, and the normal operation by the shift control means 9a is performed. The shift control in the low fuel consumption mode is performed. As a result, the gear stage having the best fuel efficiency within the range in which the vehicle does not stall becomes the target gear stage, and shift control is performed to this gear stage. In FIG. 4, steps S21, S24, S25, and S26 constitute the shift control means 9a.

  Note that the TMCU 9 is not limited to the one that always shifts according to the low fuel consumption mode. For example, normally, when the transmission 3 is shift-controlled based on a map that defines the range of each gear stage based on the engine speed and the accelerator opening, and when a predetermined condition is satisfied (for example, the driver is in the low fuel consumption mode) The shift control according to the low fuel consumption mode may be performed only when the switch is turned on.

It is the schematic of the automatic transmission control apparatus which concerns on the Example of this invention. It is a flowchart about determination of the gear stage for gear shifting. It is a flowchart about determination of a flag. It is a flowchart about determination of a target gear stage. It is a figure which shows the equal fuel consumption map A, the maximum torque diagram B, and the equal horsepower diagram C. It is explanatory drawing which shows the downshift which becomes a problem.

Explanation of symbols

1 Engine 2 Clutch 3 Transmission 5 Accelerator Pedal 6 ECU
7 Engine rotation sensor 8 Accelerator pedal opening sensor 9 TMCU
9a, S21, S24, S25, S26 Shift control means 9b, S22, S23, S24, S26 Shift prohibiting means N Current gear stage A Equivalent fuel consumption map B Maximum torque diagram C Constant horsepower diagram

Claims (2)

Shift control means for shifting to a gear stage determined to have the lowest fuel consumption rate within a range in which the vehicle does not stall;
Shift prohibiting means for prohibiting shift by the shift control means ,
Accelerator pedal when detecting deceleration of the vehicle in the state of ON, the necessary torque required to maintain the current vehicle speed to stop the deceleration, shortage of order not to decelerate the vehicle to torque currently output an automatic transmission control device which Ru determined by adding a torque,
When the shift control means is activated ,
When the required torque is smaller than the maximum torque at the current engine speed , the shift prohibiting means is operated to prohibit the shift by the shift control means ,
An automatic shift control device , wherein when the required torque is equal to or greater than the maximum torque at the current engine speed, the shift control means shifts down . Shift control means for shifting to a gear stage determined to have the lowest fuel consumption rate within a range in which the vehicle does not stall;
When a vehicle deceleration is detected,
Find the necessary torque required to stop the deceleration and maintain the current vehicle speed by adding the insufficient torque to prevent the vehicle from decelerating to the currently output torque,
When this required torque is smaller than the maximum torque at the current engine speed, the fuel consumption rate of the current gear stage is virtually replaced with the minimum value,
An automatic shift control device comprising: a shift prohibiting means for holding the current gear stage by the shift control means.

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