JP4760143B2 - Automatic transmission control device - Google Patents

Description

  The present invention relates to an automatic shift control device that automatically shifts a transmission to a gear stage that can travel with the lowest fuel consumption within a range in which a vehicle does not stall.

  In an automatic shift control device that automatically shifts a transmission, a shift control called a low fuel consumption mode that shifts the gear stage of the transmission to a gear stage that can travel with the lowest fuel consumption within a range in which the vehicle does not stall is performed. What is executed has been proposed (see, for example, Patent Document 1).

  The outline of the shift control content in the low fuel consumption mode will be described with reference to FIG.

  In FIG. 6, the horizontal axis represents the engine rotation speed, and the vertical axis represents the net average effective pressure Pme (corresponding to engine torque). A diagram indicated by a solid line A in FIG. 6 is an iso-fuel consumption diagram of the engine, and if it is on the same line, it means that the fuel consumption rate SFC is the same. In this iso-fuel consumption diagram A, the closer to the inner line, the lower the fuel consumption rate (good fuel consumption), and conversely, the closer to the outer line, the higher the fuel consumption rate (bad fuel consumption). A line indicated by a dotted line B is a maximum torque diagram of the engine.

  In the low fuel consumption mode, a minimum horsepower required for maintaining the current driving state (that is, a necessary engine output necessary for steady running in the current state) is determined, and an equal horsepower diagram C is created. The horsepower (required engine output) varies depending on the driving conditions (road slope, etc.) and the accelerator opening, that is, the engine load.

  Now, assume that the transmission is running at N gears and the engine speed is R (N). Then, based on the output torque of the engine at the current gear stage N, the acceleration of the vehicle, and the vehicle weight, the necessary torque T (N) that is the minimum required to maintain the current driving state (vehicle speed) is first obtained. Based on the calculated torque T (N) and the engine rotational speed R (N), an equal horsepower diagram C is created. That is, the required engine output (running load) is required. In FIG. 6, the symbols in parentheses for the engine speed R and the engine torque T indicate the corresponding gear stages.

  Next, based on the current engine speed R (N) and the gear ratio of each gear stage of the transmission, the virtual engine speed after the shift is determined for each gear stage of the transmission, and the virtual engine rotation is determined. Based on the speed and the constant horsepower diagram C, the required torque required to maintain the current operating state after the shift is determined for each gear stage. That is, in FIG. 6, the virtual engine rotation speed after the transmission is shifted up one stage from the current gear stage N is R (N + 1), and the torque necessary to maintain the current operating state at the N + 1 stage is T (N + 1). Further, the virtual engine rotation speed after the transmission is shifted up from the current gear stage N by two stages is R (N + 2), and the torque required to maintain the current driving state at N + 2 stage is T (N + 2). is there. In FIG. 6, only the current gear stage N to N + 2 are shown, but the virtual engine speed R and the required torque T after the shift are determined for all the gear stages of the transmission. The fuel consumption rate is determined for each gear stage of the transmission based on the virtual engine rotation speed R, the required torque T, and the iso-fuel consumption diagram A.

  Next, only the gear stage in which the required torque T is equal to or less than the maximum torque B of the engine is determined as a selectable gear stage. This is because if the required torque T is shifted to a gear stage that is larger than the maximum torque B of the engine, the vehicle will stall after the shift. Then, the gear stage having the lowest fuel consumption rate (high fuel efficiency) is selected as the target gear stage among the selectable gear stages, and the transmission is shifted to the target gear stage.

  In the example of FIG. 6, the current gear stage N and a gear stage N + 1 that is one higher than the current gear are determined as selectable gear stages, and the fuel consumption rates of both are compared. Here, since the fuel consumption rate is lower in the N + 1 stage than in the current gear stage N, the transmission is shifted up to the N + 1 stage.

JP-A-11-082084

  However, in such fuel-efficient shift control, for example, when the driver temporarily returns the accelerator pedal, such as when a vehicle traveling on an uphill road (uphill on a slope road) passes a corner, the shift of the transmission is changed. Was often performed, and the shift feeling felt by the driver sometimes deteriorated.

  The reason for this will be described with reference to FIG.

  It is assumed that the gear stage of the transmission is N and the vehicle is traveling on an uphill road, and the required torque T (N) at the N stage is slightly smaller than the maximum torque B of the engine (line C ).

  It is assumed that the vehicle approaches the corner from this state and the driver returns the accelerator pedal in front of the corner. Then, it is detected that the output torque has decreased at the moment when the accelerator pedal is returned, but the deceleration (stall) of the vehicle is not detected immediately. Therefore, it is determined that the current driving state (vehicle speed) can be maintained with the reduced output torque, and it is determined that the traveling load of the vehicle is released (reduced). That is, when the driver loosens the accelerator, the instantaneous output torque is reduced, but the change in the vehicle speed does not follow, so that it is determined to reduce the traveling load. As a result, the required torque in the N stage is calculated to be smaller than before the accelerator pedal is returned (T (N) → T ′ (N), line C → line C ′). As a result, the N + 1 stage on the higher speed side than the N stage can be selected, and the fuel consumption rate of the N + 1 stage is lower than the fuel consumption rate of the N stage, so that the transmission is shifted up to the N + 1 stage.

  Thereafter, when the driver depresses the accelerator pedal again at the corner exit, the line C ′ in FIG. 7 shifts to the line C, and the required torque T ′ (N + 1) at the N + 1 stage exceeds the maximum torque B of the engine. As a result, the N + 1 stage is excluded from the selectable gear stages, and the transmission is shifted down to the N stage.

  Thus, in the conventional shift control, when a vehicle traveling on an uphill road passes through a corner, the upshift and downshift are performed, and the shift feeling is deteriorated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic transmission control device that can solve the above-described problems and ensure a good shift feeling.

In order to achieve the above object, the present invention provides an output calculation means for obtaining a required engine output necessary for the vehicle to maintain the current driving state at predetermined intervals, and for each gear stage of the transmission of the vehicle. Determine the fuel consumption rate and required torque when the required engine output obtained by the output calculation means is maintained, and select the gear stage with the lowest fuel consumption rate among the gear stages where the required torque is less than the maximum torque of the engine. Basic shift control means for selecting the target gear stage and shifting the transmission to the target gear stage, and the output calculation means within a predetermined time from when the accelerator opening of the vehicle is decreased beyond a predetermined amount. There needs engine output obtained this time, when less than the required engine output last time, the required engine output of the last, as the necessary engine output current used by the basic shift control means Replacing the virtual manner, in which a gear shift inhibiting means for inhibiting a change in speed by the basic shift control means.

  According to the present invention, the excellent effect of ensuring a good shift feeling is exhibited.

  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 automatically shifts a multi-stage transmission 3 (here, a forward 12-stage transmission) connected to a diesel engine 1 mounted on a vehicle such as a truck via a clutch 2. .

  The engine 1 is controlled by an engine control means (ECU) 6. The ECU 6 basically operates from the detected values of the engine rotation sensor 7 that detects the rotation speed of the engine 1 and the accelerator opening sensor 8 that detects the opening of the accelerator pedal 5 (the engine rotation speed and the engine rotation speed). Engine load) is read, and the fuel injection timing and fuel injection amount (engine output) of the engine 1 are controlled based on the engine operating state.

  The clutch 2 and the transmission 3 are automatically controlled by a TMCU (basic shift 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 the present embodiment, the clutch 2 can be manually connected / disconnected by the clutch pedal 11. The clutch 2 is provided with a clutch stroke sensor 14 for detecting the position of a clutch plate (not shown), and the detected value of the clutch stroke sensor 14 is transmitted to the ECU 6 and the TMCU 9.

  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. Further, the transmission 3 is provided with an output shaft sensor 28 for detecting the rotational speed of the output shaft (not shown), and the detection value of the output shaft sensor 28 is transmitted to the TMCU 9. The TMCU 9 calculates the vehicle speed based on the detection value of the output shaft sensor 28.

  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 gear disengagement / gear-in of the transmission 3, and then 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 of the present embodiment performs the shift control as described below.

  The TMCU 9 basically shifts the transmission 3 of the vehicle to a gear stage where the fuel consumption rate is determined to be the smallest in a range where the vehicle does not stall, but the accelerator opening of the vehicle decreases beyond a predetermined amount. The shift-up of the transmission 3 is prohibited within a predetermined time after being done. The predetermined time is set to the same length as the time from when the accelerator opening is decreased until the deceleration of the vehicle is detected. Accordingly, it can be prevented that the travel load is reduced while the vehicle speed is maintained after the accelerator opening is decreased.

  More specifically, first, the TMCU 9 calculates the necessary engine output (current running load) necessary for the vehicle to maintain the current driving state (vehicle speed), the output torque of the current gear, the vehicle acceleration, and the vehicle weight. And at predetermined intervals based on the engine rotation speed. Next, the TMCU 9 determines a virtual fuel consumption rate and a virtual required torque when the required engine output is maintained for each gear stage of the transmission 3. Next, the TMCU 9 selects the gear stage having the lowest virtual fuel consumption rate as the target gear stage among the gear stages having the virtual required torque equal to or less than the maximum torque of the engine 1. Next, the TMCU 9 basically shifts the transmission 3 to the target gear stage. However, the TMCU 9 is currently (currently) within a predetermined time from when the accelerator opening of the vehicle is decreased beyond a predetermined amount. When the required engine output obtained in the cycle is smaller than the required engine output obtained by TMCU 9 in the previous cycle (ie, in the previous cycle) (that is, when there is a possibility that the traveling load may be reduced), Shifting of the machine 3 (specifically, upshifting) is prohibited.

  Further, in the present embodiment, when the TMCU 9 prohibits the shift of the transmission 3, first, the required engine output of this time is within a predetermined time from when the accelerator opening of the vehicle is decreased beyond a predetermined amount. When it is smaller than the previous required engine output, the previous required engine output is virtually replaced with the current required engine output. Thereafter, as described above, for each gear stage of the transmission 3, the virtual fuel consumption rate and the virtual required torque when the replaced required engine output is maintained are determined, and the target gear stage is selected. In other words, in FIG. 7, if the equal horsepower diagram of the previous required engine output is C and the equal horsepower diagram of the current required engine output is C ′, the current C ′ is replaced with the previous C, so The same target gear as the previous time is selected.

  This point will be described below with reference to the flowcharts of FIGS. These flowcharts are executed by the TMCU 9 every predetermined cycle (for example, 500 ms (milliseconds)), and are executed in the order of flowcharts of FIGS. 2, 3, and 4, for example.

  First, using FIG. 2 and FIG. 3, description will be given of the contents of control for determining whether or not a predetermined time has elapsed since the accelerator opening of the vehicle was decreased beyond a predetermined amount.

  First, in step S21 of FIG. 2, it is determined whether or not the accelerator pedal 5 is returned. Specifically, the TMCU 9 determines that the accelerator opening (previous accelerator opening) detected by the accelerator opening sensor 8 in the previous cycle exceeds the accelerator opening (current accelerator opening) detected in the current cycle. Determine whether or not.

  When it is determined in step S21 that the previous accelerator opening exceeds the current accelerator opening (when the accelerator pedal 5 is returned), the process proceeds to step S22. In step S22, the return amount of the accelerator pedal 5 is obtained. Specifically, the TMCU 9 calculates an accelerator opening difference Δ obtained by subtracting the current accelerator opening from the previous accelerator opening. Thereafter, the TMCU 9 proceeds to step S23.

  In step S23, the TMCU 9 determines whether or not the accelerator opening difference Δ exceeds a set value 1 (predetermined amount). The set value 1 is large enough to determine whether or not the accelerator pedal 5 has been returned by the driver's intention, and the set value 1 of the present embodiment is when the difference between the accelerator fully open and fully closed is 100%. 5%. By the above steps S21 to S23, it is determined whether or not the accelerator opening of the vehicle has been decreased beyond a predetermined amount.

  If it is determined in step S23 that the accelerator opening difference Δ exceeds the set value 1, the process proceeds to step S24. In step S24, TMCU 9 sets the accelerator OFF flag to ON, and then proceeds to step S25. Note that the accelerator OFF flag of this embodiment is set to either ON or OFF. For example, when the vehicle is started, OFF is set as an initial value.

  On the other hand, if it is determined in step S21 that the previous accelerator opening does not exceed the current accelerator opening, and if it is determined in step S23 that the accelerator opening difference Δ does not exceed the set value 1, the accelerator OFF flag is set. Without proceeding to step S25.

  In step S25, the TMCU 9 determines whether or not the accelerator OFF timer stored in the TMCU 9 is less than a set value 2 (1s (1 second in the illustrated example)).

  Here, the accelerator OFF timer is for measuring the time from when the accelerator opening is decreased beyond a predetermined amount to the present, and in this embodiment, the TMCU 9 executes the flowchart shown in FIG. Then, the value of the accelerator OFF timer is manipulated.

  In step S31 of FIG. 3, the TMCU 9 determines whether or not the accelerator OFF flag is ON. If the TMCU 9 determines that the accelerator OFF flag is ON, the process proceeds to step S32, and the accelerator OFF timer is incremented (added) by a predetermined increment value (500 ms in this embodiment). For example, the increment value is set to be the same as the predetermined cycle in which the TMCU 9 executes the flowchart of FIG. On the other hand, if the TMCU 9 determines that the accelerator OFF flag is not ON, the TMCU 9 does not increment.

  Now, returning to FIG. 2, in the present embodiment, the setting value 2 in step S25 is 1s, which is larger than the increment value of the accelerator OFF timer. The accelerator OFF timer is set to an initial value (in this embodiment, 0 s), for example, when the vehicle is started.

  If it is determined in step S25 that the accelerator OFF timer exceeds the set value 2, the accelerator OFF flag and the accelerator OFF timer are initialized in step S26 and the next step S27. Specifically, the TMCU 9 sets the accelerator OFF flag to OFF in step S26, and clears the accelerator OFF timer (sets 0s) in step S27.

  On the other hand, if it is determined in step S25 that the accelerator OFF timer does not exceed the set value 2, the accelerator OFF flag and the accelerator OFF timer are not changed.

  As described above, the accelerator OFF flag of the present embodiment is set to ON for less than 1 second after the accelerator opening is decreased beyond a predetermined amount, and is set to OFF otherwise.

  Next, the control contents for prohibiting a shift using the accelerator OFF flag will be described with reference to FIG.

  First, in step S41 of FIG. 4, the TMCU 9 stores the traveling load (necessary engine output) (hereinafter, stored traveling load) calculated in step S42 described later in the previous cycle.

  Next, in step S42, the TMCU 9 calculates a current travel load (hereinafter, current travel load) based on the current output torque, vehicle speed, vehicle acceleration, vehicle weight, and engine speed.

  Next, in step S43, the TMCU 9 determines whether or not the accelerator OFF flag stored in the TMCU 9 is ON. As described above, the accelerator OFF flag is kept ON for less than a predetermined time (1 s) after the accelerator pedal 5 is returned beyond a predetermined return amount.

If it is determined in step S43 that the accelerator OFF flag is ON, the process proceeds to step S44. In step S44, TMCU 9 is stored traveling load stored in step S4 1 determines whether or not more than the current running load calculated in step S42.

  If it is determined in step S44 that the stored travel load exceeds the current travel load, the process proceeds to step S45. In step S45, the TMCU 9 virtually replaces the stored travel load (previous travel load) with the current travel load (current travel load).

  Thereafter, as described above, the TMCU 9 determines the virtual fuel consumption rate and the virtual required torque when the replaced travel load (that is, the required engine output) is maintained for each gear stage of the transmission 3, The gear stage with the lowest virtual fuel consumption rate is selected as the target gear stage among the gear stages whose required torque is equal to or less than the maximum torque of the engine 1. However, when step S45 is executed, the required engine output is not changed. The current gear stage is selected as the target gear stage. That is, shifting (specifically, upshifting) of the transmission 3 is substantially prohibited.

  Thus, for example, when a vehicle traveling on an uphill road approaches the corner and the driver returns the accelerator pedal 5 beyond a predetermined amount (about 5% in this embodiment) at the corner entrance, the vehicle returns. The immediately preceding traveling load is held as a traveling load for selecting the target gear stage for a predetermined time (in this embodiment, 1 second). The predetermined time is set to the same length as the time from when the accelerator pedal 5 is returned until the deceleration of the vehicle is detected. Thereby, when the accelerator pedal 5 is returned, it can be prevented that the traveling load is mistakenly reduced, and the shift up can be suppressed.

  After a predetermined time, the process branches to step S26 and step S27 in step S25 of FIG. 2, and the accelerator OFF flag is initialized. In step S43 of FIG. 4, it is determined that the accelerator OFF flag is not ON (OFF). Is done. In this case, the above-described shift control (see, for example, FIG. 6) is performed, and the transmission 3 is shifted to a gear stage that is determined to have the lowest fuel consumption rate within a range where the vehicle does not stall.

  Here, when the vehicle travels on an uphill road, the shift-up of the transmission 3 is further suppressed (prohibited) even after a predetermined time has elapsed and it is determined that the vehicle is decelerating. Become.

  This point will be described with reference to FIG. In FIG. 5, the horizontal axis represents the engine rotation speed, and the vertical axis represents the net average effective pressure Pme (corresponding to engine torque). In addition, a diagram indicated by a solid line A in FIG. 5 is an iso-fuel consumption diagram of the engine 1, and a line indicated by a dotted line B is a maximum torque diagram (torque maximum line) of the engine 1.

  When it is determined that the vehicle is in a decelerating state, the required torque T (N) at the current gear stage needs to cancel the deceleration of the vehicle, and thus becomes a larger value than the current output torque T0. Further, since the vehicle is traveling on the uphill road, the required torque T (N) at the current gear stage is located in the vicinity of the maximum torque B of the engine 1. Therefore, when the equal horsepower diagram C is created based on the required torque T (N), the required torque T (N + 1) exceeds the maximum torque B at the gear stage N + 1 corresponding to the upshift, and as a result, the upshift is suppressed. The

  For example, when the slope of the uphill road where the vehicle is traveling is substantially constant, the traveling load (equal horsepower diagram C) is approximately the same immediately before the accelerator pedal 5 is returned and after a predetermined time has elapsed. . Therefore, it is possible to prevent the upshift and the downshift from being repeated unnecessarily during traveling on the uphill road.

  Now, returning to FIG. 4, when it is determined in step S44 that the stored travel load does not exceed the current travel load, the target gear stage is selected based on the current travel load. That is, in this case, shifting is not prohibited.

  As described above, according to the automatic transmission control device of this embodiment, it is determined that the vehicle is in a deceleration (stall) state, for example, when the accelerator opening is decreased while the vehicle is traveling uphill. In the meantime, since the transmission 3 is not shifted, the number of shifts can be reduced and a good shift feeling can be secured.

In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.
For example, in the present embodiment, the required engine output (running load) is directly held. However, the present invention is not limited to this. For example, the required torque is held and the required engine output is calculated from the required torque. May be.

It is the schematic of the automatic transmission control apparatus which concerns on one Embodiment of this invention. It is a control flow which shows the control content of a gear shift prohibiting means. It is a control flow which shows the control content of a gear shift prohibiting means. It is a control flow which shows the control content of a gear shift prohibiting means. It is a figure for demonstrating the control content of a basic gear shift control means and a gear shift prohibiting means. It is a figure for demonstrating the shift control by a low fuel consumption mode. It is a figure for demonstrating the state in which gear shifting is performed frequently, such as when a vehicle passes a corner.

Explanation of symbols

1 Engine 2 Clutch 3 Transmission 5 Accelerator Pedal 6 ECU
7 Engine rotation sensor 8 Accelerator opening sensor 9 TMCU (basic shift control means, shift prohibiting means)
28 Output shaft sensor

Claims (1)

An output calculating means for obtaining a required engine output required for the vehicle to maintain the current driving state at predetermined intervals;
For each gear stage of the transmission of the vehicle, a fuel consumption rate and a required torque when the required engine output obtained by the output calculating means is maintained are determined, and the gear stage where the required torque is less than the maximum torque of the engine Basic shift control means for selecting the gear stage having the lowest fuel consumption rate as the target gear stage and shifting the transmission to the target gear stage,
When the required engine output calculated this time by the output calculation means is smaller than the previous required engine output within a predetermined time from when the accelerator opening of the vehicle is reduced beyond a predetermined amount, the previous required engine An automatic shift control device comprising: a shift prohibiting unit that virtually replaces an output with a required engine output of the present time used by the basic shift control unit and prohibits a shift by the basic shift control unit .

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