JP4506155B2 - Automatic transmission control device - Google Patents

Description

  The present invention relates to an automatic shift control device that performs shift control from a current gear stage to a gear stage that reduces a fuel consumption rate while maintaining the current driving state of the vehicle, and in particular, has a margin in the driving force of a vehicle after a shift. The present invention relates to an automatic transmission control device that can obtain necessary acceleration.

  In recent years, various automatic shift control devices for vehicle transmissions have been proposed that perform shift control from a current gear to a gear that reduces the fuel consumption rate while maintaining the current driving state of the vehicle (for example, Patent Document 1), the present inventor has developed an automatic transmission control device as described below.

  This automatic transmission control device is at least necessary to maintain the maximum engine torque determined based on the engine speed when shifting from the current gear stage and the current driving state of the vehicle for each gear stage of the transmission. The required torque and the fuel consumption rate when the current driving state of the vehicle is maintained, and the gear stage having the smallest fuel consumption rate is selected from the gear stages at which the required torque is not more than the maximum torque. The gear shifts from the gear to the gear. According to such shift control, the vehicle can be prevented from stalling after shifting by selecting a gear stage at which the required torque is equal to or less than the maximum torque, and low fuel consumption can be achieved.

  The outline of this shift control will be described with reference to FIG.

  First, based on the current engine speed R (N) of the gear stage N, the engine speeds R (N + 1), R (N + 2), R (N + 3),... Ask for. The symbols in parentheses indicate the corresponding gear stages. Then, based on these engine rotation speeds, the maximum engine torques T ′ (N + 1), T ′ (N + 2), T ′ (N + 3)... Ask.

  Further, the minimum required torque T (N) required to maintain the current driving state of the vehicle is obtained based on the current engine torque, and the required torque T (N) and the engine rotational speed R at the current gear stage N are obtained. From (N), the horsepower required for steady running in the current driving state is obtained. Then, based on the horsepower, an equal horsepower diagram C using the engine speed and the engine torque as parameters is created. The torque on the equal horsepower diagram C is the minimum necessary torque T necessary for maintaining the current driving state of the vehicle after the shift. Using this equal horsepower diagram C, required torques T (N + 1), T (N + 2), T (N + 3),... Are obtained at engine speeds R (N + 1), R (N + 2), R (N + 3),. .

  Further, in FIG. 5, A is an isofuel consumption diagram of the engine, and if it is on the same line, it means that the fuel consumption rate SFC is the same, and this isofuel consumption diagram A approaches the inner line. The better the fuel consumption, the worse the fuel consumption gets worse as the outer line gets closer. Using this iso-fuel consumption diagram A, the fuel consumption rate at engine speeds R (N + 1), R (N + 2), R (N + 3)... After shifting on the equi-horsepower diagram C is obtained.

  As described above, when the maximum torque T ′, the required torque T, and the fuel consumption rate are obtained for each gear stage after the shift, the most of the gear stages at which the required torque T is equal to or less than the maximum torque T ′. A gear stage having a small fuel consumption rate is selected as a target gear stage, and shift control is performed from the current gear stage to this gear stage. As a result, the shift control can be performed from the current gear stage to the gear stage having the smallest fuel consumption rate while maintaining the current driving state of the vehicle.

  In FIG. 5, assuming that the current gear stage N is shifted up to N + 3, the required torque T (N + 3) exceeds the maximum torque T ′ (N + 3), so the vehicle stalls. , N + 3 are deselected. Therefore, the N + 2 and N + 1 stages where such a situation does not occur are candidates for selection, and the N + 2 stage having a low fuel consumption rate is the target gear stage, and the speed is shifted to the N + 2 stage.

Japanese Patent Publication No. 5-14133

  As described above, when the shift control is performed from the current gear stage to the gear stage having the smallest fuel consumption rate while maintaining the current driving state of the vehicle, the gear stage to be shifted up along the constant horsepower diagram C is determined. As a result, the shift control is performed to the high-speed side gear stage (N + 2 stage in the example) that has the lowest fuel consumption and does not exceed the maximum torque diagram B.

  According to this control, the necessary torque T <maximum torque T ′ is ensured in the gear stage after the shift, and the vehicle does not stall after the shift, but the difference between the necessary torque T and the maximum torque T ′, that is, the margin drive The force X1 becomes small. For this reason, even if it is attempted to accelerate the vehicle after shifting, a situation in which the necessary acceleration cannot be obtained may occur in a situation where the gear is in a high speed gear stage and the accelerator is fully opened.

  Further, when the engine overheats, the maximum torque diagram B in FIG. 5 decreases as a whole, so that the marginal driving force X1 becomes substantially small or becomes zero to minus, resulting in poor acceleration or stalling of the vehicle after shifting. .

  Accordingly, an object of the present invention, which was created to solve the above-described problems, is an automatic shift control device that performs shift control to a gear stage that reduces the fuel consumption rate while maintaining the current driving state of the vehicle. An object of the present invention is to provide an automatic transmission control device capable of suppressing a vehicle acceleration failure at a gear stage.

  In order to achieve the above object, the invention according to claim 1 is provided with shift control means for performing shift control from the current gear stage to the gear stage having the smallest fuel consumption rate while maintaining the current driving state of the vehicle. The control means must be at least necessary to maintain the maximum engine torque determined for each gear stage of the transmission based on the engine speed when shifting from the current gear stage and the current driving state of the vehicle. The torque and the fuel consumption rate when the current driving state of the vehicle is maintained are obtained, and when the current gear stage is a predetermined level or less, the fuel consumption is the highest among the gear stages where the required torque is the maximum torque or less. If the gear is shifted to a gear stage with a small ratio and the current gear stage is a gear stage on the higher speed side than the predetermined stage, the maximum torque is virtually reduced and the required torque is less than the virtual maximum torque. Become the gear stage In which most fuel consumption rate is shifted to the small gear.

The invention according to claim 2 is a dependent invention of the invention according to claim 1, wherein the shift control means further processes the maximum torque virtually smaller when the engine overheats, and The gear shifts to the gear stage with the smallest fuel consumption rate among the gear stages where the torque is equal to or less than the virtual maximum torque.

  According to the present invention, the following effects can be exhibited.

  (1) According to the first aspect of the present invention, the required maximum torque is compared with the virtual maximum torque obtained by virtually reducing the maximum torque at the high speed side gear stage. Force can be secured, and acceleration failure of the vehicle after shifting can be suppressed. Further, since the maximum torque is directly compared with the required torque at the low speed side gear stage, low fuel consumption can be ensured.

(2) According to the invention of claim 2, in addition to the effect of the invention of claim 1, when the engine is overheated, the virtual maximum torque obtained by virtually reducing the maximum torque is compared with the required torque. because there can be ensured a certain reserve drive force after shifting, Ru can be suppressed poor acceleration of the vehicle after the shift.

  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 (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 this 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 its output shaft (not shown), and the detection value of the output shaft sensor 28 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 is a feature of the present embodiment, and executes control for shifting from the current gear stage to a gear stage where the fuel consumption rate is reduced while maintaining the current driving state of the vehicle. . Here, the feature of this embodiment is that the content of the speed change control varies depending on whether the current gear stage is a low speed side gear stage that is equal to or lower than a predetermined stage or a high speed side gear stage. In the high-speed side gear stage, a marginal driving force after shifting is ensured to suppress the acceleration failure of the vehicle, and in the low-speed side gear stage, low fuel consumption control is maintained.

  The outline is as follows. As shown in FIG. 5, the TMCU 9 has a maximum torque T ′ of the engine 1 determined based on the engine speed R when shifting from the current gear stage for each gear stage of the transmission 3, and The minimum required torque T required to maintain the current vehicle operating state at the current gear stage and the fuel consumption rate when the current vehicle operating state at the current gear stage is maintained are obtained. Since this point is as described in the background art section, detailed description is omitted.

  When the current gear detected by the gear position sensor 23 is a low-speed gear that is not higher than a predetermined gear, the required torque T is not more than the maximum torque T ′ as shown in FIG. The gear stage having the smallest fuel consumption rate is set as the target gear stage, and the gear is shifted to this gear stage. Such shift control is also as described in the “Background Art” section, and thus detailed description thereof is omitted.

  On the other hand, when the current gear stage is a gear stage on the higher speed side than the predetermined stage, the maximum torque T ′ is virtually reduced as shown in FIG. Shifting to a gear stage having the smallest fuel consumption rate among the gear stages having torque T ″ or less.

  By such shift control, the maximum torque T ″ obtained by virtually reducing the maximum torque T ′ is compared with the necessary torque T at the high speed side gear stage, so that a predetermined margin drive is performed after the shift. Force can be secured, and acceleration failure of the vehicle after shifting can be suppressed. Further, since the maximum torque T 'is directly compared with the required torque T at the low speed side gear stage, low fuel consumption can be ensured.

  Hereinafter, the shift control will be described in detail.

  In the present embodiment, the predetermined stage is four (fourth speed) out of the twelve forward stages of the transmission 3. Therefore, when the current gear stage N is a low speed gear stage (1st to 4th speed) of the fourth speed or less, the required torque T and the maximum torque T ′ of each gear stage are compared based on FIG. The gear is shifted to the gear stage (N + 2 in the example) with the smallest fuel consumption rate among the gear stages (N + 2, N + 1 in the example) where the required torque T is equal to or less than the maximum torque T ′. Thus, the shift control is performed from the current gear stage to the gear stage having the smallest fuel consumption rate while maintaining the current driving state of the vehicle at the current gear stage.

  On the other hand, when the current gear stage N is a high-speed gear stage (5th to 12th speed) exceeding the fourth speed, the maximum torque T ′ is virtually reduced (to 95%) based on FIG. The virtual maximum torque T ″ thus compared with the required torque T is shifted to a gear stage N + 1 having the smallest fuel consumption rate among the gear stages at which the required torque T is equal to or less than the virtual maximum torque T ″. As a result, in the high-speed side gear stage, priority is given to securing a marginal driving force after shifting rather than low fuel consumption.

  In the illustrated example, since the required torque T (N + 2) exceeds the virtual maximum torque T ″ (N + 2) at the N + 2 stage, the speed is not shifted to the N + 2 stage, and the N + 1 stage where such a situation does not occur. The speed is changed. Thus, a predetermined marginal driving force X2 can be ensured after the shift at the high speed side gear stage (5th to 12th speed), and the acceleration failure of the vehicle after the shift can be suppressed.

  That is, in FIG. 2, since the required torque T is less than or equal to the maximum torque T ′ (see FIG. 5) at the N + 2 stage, even if the vehicle is shifted up to the N + 2 stage, the vehicle will not stall, but is shifted up to the N + 2 stage. Then, since the marginal driving force X1 becomes extremely small, there may occur a situation where necessary acceleration cannot be obtained even if the vehicle is accelerated after shifting.

  Here, at the high speed gear stage (5th to 12th speed), the vehicle is more difficult to accelerate than the low speed gear stage (1st speed to 4th speed) because of the gear ratio. The problem of poor acceleration of the vehicle due to the small size is likely to occur.

  Therefore, in the present embodiment, in the high speed side gear stage, the maximum torque T ′ serving as a threshold value for determining the gear stage after the shift is virtually reduced, and the virtual maximum torque T ″ is used as the threshold value. ing. As a result, the N + 2 stage that can be shifted up at the low-speed gear stage is excluded from the high-speed gear stage and shifted to the N + 1 stage, which is sufficient for accelerating the vehicle at the high-speed gear stage. A sufficient margin driving force X2 is secured.

  As described above, it is not appropriate to perform the shift control that virtually reduces the maximum torque T ′ and uses the virtual maximum torque T ″ as a threshold at the low-speed gear stage. This is because, at the low gear stage, the vehicle is more likely to accelerate than the high gear stage because of the gear ratio, and the shift control using the virtual maximum torque T ″ as a threshold value at the low gear stage. As shown in FIG. 4, there is a problem that the overshoot becomes large.

  This will be described. The TMCU 9 is used for automatic shift control of the transmission 3 of the engine 1 that generates a large torque such as a large truck. Therefore, when shifting the transmission 3, the actual accelerator opening Regardless of the engine, the fuel injection amount is reduced, and the clutch is disengaged while the engine output is reduced to some extent, thereby suppressing the clutch disengagement shock.

  However, at the low speed gear stage, a large margin driving force X2 is generated, so the gradient of the engine rotation speed becomes steep, and the engine rotation speed increases due to the inertial force even after the fuel injection amount is reduced. Overshoot. At this time, if the virtual maximum torque T ″ is set as a threshold value, the shift timing is further delayed and the fuel consumption is deteriorated.

  Therefore, the predetermined stage is set to the lowest gear stage among the gear stages in which the overshoot does not become a problem even when the shift control using the virtual maximum torque T ″ as a threshold is performed. Specifically, the overshoot correlates with a rising gradient of the engine speed, and if this gradient is equal to or less than a predetermined angle, the overshoot is reduced or eliminated. Therefore, the gear stage at which the gradient becomes a predetermined angle is set to the predetermined stage.

  The shift control by the TMCU 9 will be described based on the flowchart of FIG. This flowchart is executed every predetermined period.

  First, in step S1, when it is assumed that the gear is shifted from the current gear to each gear, the engine speed after the shift is obtained. The engine speed after the shift is obtained by using the engine speed at the current gear stage detected by the engine rotation sensor 7, the gear ratio at the current gear stage, and the gear ratio at each gear stage after the shift. Calculated.

  In step S2, the engine maximum torque T 'in each gear stage after the shift is determined based on the engine speed after the shift determined in step S1 and the maximum torque diagram B shown in FIGS.

  In step S3, the current gear stage detected by the gear position sensor 23 is compared with a predetermined stage (fourth speed in 12 stages in the figure), and the current gear stage is a predetermined stage (fourth speed). It is determined whether or not the gear is on the higher speed side.

  If the current gear stage is a higher gear stage (5th to 12th speed) than the predetermined stage (4th speed), the process proceeds to step S4, and the first predetermined coefficient (see FIG. In the example, 0.95) is multiplied to obtain the virtual maximum torque T ″ at each gear stage after the shift.

  As described with reference to FIG. 2, the virtual maximum torque T ″ and the required torque T are compared at each gear stage after the shift, and the required torque is equal to or less than the virtual maximum torque T ″. The gear stage having the smallest fuel consumption rate among the stages is set as the target gear stage, and shift control is performed to the target gear stage.

  On the other hand, if the current gear stage is a low-speed gear stage (1st to 4th speed) that is equal to or lower than a predetermined stage (4th speed), as described with reference to FIG. T ′ is compared with the required torque T, and the gear stage with the smallest fuel consumption rate among the gear stages where the required torque T is equal to or less than the maximum torque T ′ is set as the target gear stage, and shift control is performed to the target gear stage. .

  As described above, in the present embodiment, in the high speed side gear stage, the maximum torque T ′ serving as a threshold for determining the gear stage after the shift is virtually reduced, and the virtual maximum torque T ″ is required. Compared with the torque T, the maximum torque T ′, which is the threshold value, is directly compared with the required torque T at the low speed side gear stage. It is possible to achieve compatibility with control.

  Next, in the control based on step S5 and step S6, when the engine is overheated, as shown in FIG. 2, the maximum torque diagram B is lowered as a whole, so that the marginal driving force X1 is substantially reduced and the speed change is performed. This is control for solving the problem that the acceleration failure of the subsequent vehicle is likely to occur. This control is performed regardless of whether the gear stage is on the high speed side or the low speed side.

  In step S5, it is determined whether or not the water temperature of the engine 1 exceeds a preset predetermined temperature (100 ° C. in the example). Thereby, it can be determined whether the engine 1 is overheated. Note that overheating may be determined based on oil temperature or oil pressure.

  When the water temperature exceeds the predetermined temperature (100 ° C.), it is determined that the engine is overheated, and the process proceeds to step S6, where the first predetermined coefficient (0.95 in the example) is added to the engine maximum torque T ′ obtained in step S2. ) And a second predetermined coefficient (0.9 in the example), the virtual maximum torque T ′ ″ at each gear stage after the shift is obtained.

  Then, as described with reference to FIG. 2, the virtual maximum torque T ′ ″ and the required torque T are compared at each gear stage after the shift, and the required torque is less than or equal to the virtual maximum torque T ′ ″. The gear stage having the smallest fuel consumption rate is set as the target gear stage, and shift control is performed to the target gear stage.

  On the other hand, when the water temperature is equal to or lower than the predetermined temperature (100 ° C.), it is determined that overheating has not occurred, and as described with reference to FIG. And the gear stage having the smallest fuel consumption rate among the gear stages in which the required torque T is equal to or less than the maximum torque T ′ is set as the target gear stage, and shift control is performed to the target gear stage.

  As described above, when the engine 1 is overheated, the maximum torque T ′ serving as a threshold for determining the gear stage after the shift is virtually reduced, and the virtual maximum torque T ′ ″ is set to the necessary torque. When the overheat is not overheated, the maximum torque T ′ that is the threshold value is directly compared with the required torque T, so that the acceleration failure of the vehicle after the shift during overheat is suppressed and the overheat is overheated. It is possible to achieve both low fuel consumption control when there is not.

The present invention is not limited to the above embodiment. For example, the shift control by steps S1 to S4 and the shift control by steps S5 and S6 do not necessarily have to be performed in series as shown in the figure, and steps S5 and S6 may be omitted . Further, in step S 6, only one of the first predetermined value or the second predetermined value may be subjected to maximum torque. Further, the predetermined stage is not limited to the fourth speed, and if the first predetermined value is 1 or less, it is not limited to 0.95, and if the second predetermined value is 1 or less, it is not limited to 0.9. The temperature is not limited to 100 ° C.

It is the schematic of the automatic transmission control apparatus which concerns on the Example of this invention. It is a figure for demonstrating the shift control using a virtual required torque. It is a flowchart which shows the control content concerning one Embodiment of this invention. It is a figure for demonstrating the overshoot at the time of gear shifting. It is a figure for demonstrating the shift control using required torque.

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 (shift control means)
T Required torque T 'Maximum torque T''Virtual maximum torque

Claims (2)

Shift control means for performing shift control from the current gear stage to the gear stage having the smallest fuel consumption rate while maintaining the current driving state of the vehicle,
The shift control means includes
For each gear stage of the transmission, the maximum engine torque determined based on the engine speed when shifting from the current gear stage, the minimum required torque to maintain the current driving state of the vehicle, and the current The fuel consumption rate when maintaining the driving state of the vehicle,
When the current gear stage is less than or equal to a predetermined stage, the gear shifts to the gear stage with the lowest fuel consumption rate among the gear stages where the required torque is less than or equal to the maximum torque. In the case of a gear stage, the maximum torque is virtually reduced and the gear is shifted to the gear stage with the lowest fuel consumption rate among the gear stages where the required torque is less than or equal to the virtual maximum torque. A feature of an automatic transmission control device. The shift control means includes
When the engine overheats, the maximum torque is virtually reduced and the gear shifts to the gear stage with the lowest fuel consumption rate among the gear stages where the required torque is less than or equal to the virtual maximum torque.
The automatic transmission control device according to claim 1 .

Images