Control device for internal combustion engine

Abstract

The invention relates to a control device for an internal combustion engine, which can restrain rotation fluctuation of the internal combustion engine generated when a starting clamping element is clamped. A shift lever (300) that performs a switching operation between a non-traveling position and a traveling position is switched from the non-traveling position to the traveling position. When either a condition that the amount of change in the hydraulic pressure of hydraulic oil supplied to a starting engagement element (52s) of a transmission mechanism (50) is equal to or greater than a preset value or a condition that a target time has elapsed since a shift lever (300) is switched from a non-travel position to a travel position until the starting engagement element (52s) begins to engage is satisfied, the shift lever (300) is shifted from the non-travel position to the travel position. The control device (100) performs feedback control on the engine torque of the internal combustion engine (10) so that the engine rotational speed of the internal combustion engine (10) becomes a target rotational speed, and starts torque control for increasing the engine torque by a correction amount on the increasing side when the load torque increase speed of the torque converter (40) is faster than when the load torque increase speed is slower.

Description

Technical Field

[0001] This invention relates to a control device for an internal combustion engine. Background Technology

[0002] Patent Document 1 describes a vehicle with an automatic transmission, which includes a torque converter and a transmission mechanism with multiple friction engagement elements. The torque converter has a pump impeller connected to the output shaft of an internal combustion engine and a turbine impeller connected to the input shaft of the transmission mechanism. Additionally, the vehicle includes a shift lever for switching between a non-driving position and a driving position.

[0003] The transmission mechanism's friction engagement element includes a starting engagement element. When the shift lever is switched from a non-driving position to a driving position, this starting engagement element switches its operating state from a released state to an engaged state. A non-driving position refers to a position where the vehicle is not moving, such as the parking position (P position) or neutral position (N position). Conversely, a driving position refers to a position where the vehicle is moving, such as the drive position (D position) or reverse position (R position). The starting engagement element is an engagement element that forms the first gear for forward movement and an engagement element that forms the gear for reverse movement.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2021-167611 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In such vehicles, when the gear shift lever is switched from a non-driving position to a driving position, the starting engagement element switches from a released state to an engaged state. During this switch, if the starting engagement element engages, the torque converter load torque begins to increase. Furthermore, the torque converter load torque refers to the load torque of the turbine impeller resisting the rotation of the pump impeller. If the torque generated by the internal combustion engine is excessive or insufficient relative to the increase in the torque converter load torque, rotational fluctuations will occur within the internal combustion engine.

[0009] Therefore, feedback control of the internal combustion engine torque can be considered to make the engine speed the target speed, and torque control can be implemented to increase the correction amount of the internal combustion engine torque towards the increasing side when the torque converter load torque increases rapidly, compared to when it increases slowly. However, if the timing of the start of such torque control deviates from the timing of the engagement of the starting engagement element, an excess or deficiency of internal combustion engine torque relative to the increase in torque converter load torque will occur. Therefore, it may be impossible to suppress the rotational fluctuations of the internal combustion engine that occur when the starting engagement element engages.

[0010] Methods for solving problems

[0011] The control device for solving the above-mentioned problems is applied to an internal combustion engine mounted in a vehicle, the vehicle having an automatic transmission and a shift lever, the automatic transmission having: a transmission mechanism having a plurality of friction engagement elements; and a torque converter having a pump impeller connected to the output shaft of the internal combustion engine and a turbine impeller connected to the input shaft of the transmission mechanism, the shift lever performing a switching operation between a non-driving position and a driving position, the friction engagement elements having a starting engagement element, the starting engagement element switching its working state from a released state to an engaged state when the shift lever switches from a non-driving position to a driving position. When the load torque of the turbine impeller resisting the rotation of the pump impeller is set as the torque converter load torque, and the rate of increase of the torque converter load torque is set as the rate of increase of the load torque, the control device performs feedback control on the internal combustion engine torque generated by the internal combustion engine in such a way that the internal combustion engine speed becomes the target speed. When the rate of increase of the load torque is faster, torque control is implemented to increase the correction amount of the internal combustion engine torque towards the increasing side compared to when it is slower. Furthermore, the control device performs the following processing: obtaining the target time from when the shift lever is switched from the non-driving position to the driving position until the starting engagement element begins to engage; and starting the torque control when either of the following conditions is met: after the shift lever is switched from the non-driving position to the driving position, the change in the hydraulic pressure of the working oil supplied to the starting engagement element is greater than or equal to a preset value, or the target time has elapsed since the shift lever was switched from the non-driving position to the driving position.

[0012] Furthermore, a control device for an internal combustion engine used to solve the aforementioned problems is applied to an internal combustion engine mounted in a vehicle. The vehicle has an automatic transmission and a shift lever. The automatic transmission includes: a transmission mechanism having multiple friction engagement elements; and a torque converter having a pump impeller connected to the output shaft of the internal combustion engine and a turbine impeller connected to the input shaft of the transmission mechanism. The shift lever performs switching operations between a non-driving position and a driving position. The friction engagement elements include a starting engagement element, which switches its operating state from a released state to an engaged state when the shift lever switches from a non-driving position to a driving position. When the load torque of the turbine impeller resisting the rotation of the pump impeller is set as the torque converter load torque, and the rate of increase of the torque converter load torque is set as the rate of increase of the load torque, the control device performs feedback control on the internal combustion engine torque generated by the internal combustion engine in such a way that the internal combustion engine speed becomes the target speed. When the rate of increase of the load torque is faster, torque control is implemented to increase the correction amount of the internal combustion engine torque towards the increasing side compared to when it is slower. Furthermore, the control device performs the following processing: obtaining the target time from when the shift lever is switched from the non-driving position to the driving position until the starting engagement element begins to engage; and starting the torque control when either of the following conditions is met: after the shift lever is switched from the non-driving position to the driving position, the change in the turbine impeller speed is above a preset value, or the target time has elapsed since the shift lever was switched from the non-driving position to the driving position.

[0013] Invention Effects

[0014] According to the present invention, it is possible to suppress rotational fluctuations of the internal combustion engine that occur when the starting engagement element engages. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the structure of a vehicle equipped with a control device according to one embodiment.

[0016] Figure 2 This is a flowchart illustrating the process performed by the control device in this embodiment.

[0017] Figure 3 This is a flowchart illustrating the process performed by the control device in this embodiment.

[0018] Figure 4 This is a flowchart illustrating the process performed by the control device in this embodiment.

[0019] Figure 5 This is a timing diagram showing the shift of values ​​when the operating state of the starting engagement element switches from the released state to the engaged state. Figure 5 (a) shows the shift in the FB correction amount. Figure 5 (b) shows the shifts in internal combustion engine speed, target speed, and turbine speed. Figure 5 (c) shows the movement of the control start mark. Figure 5 (d) shows the shift in gear position. Figure 5 (e) shows the shift in torque converter load torque.

[0020] Figure 6 This is a flowchart illustrating the process performed by the control device in a variation of this embodiment.

[0021] Figure 7 This is a flowchart illustrating the process performed by the control device in a variation of this embodiment.

[0022] Explanation of reference numerals in the attached figures

[0023] 10…internal combustion engine, 40…torque converter, 42P…pump impeller, 42T…turbine impeller, 45…lock-up clutch, 50…transmission mechanism, 52…friction engagement element, 52s…starting engagement element, 100…control device, 200…automatic transmission, 300…gear shift lever, 500…vehicle. Detailed Implementation

[0024] The following is for reference Figures 1-5 An embodiment of the control device for an internal combustion engine will be described.

[0025] <Vehicle Structure>

[0026] like Figure 1 As shown, the internal combustion engine 10 of the vehicle 500 includes an intake passage 11, a throttle valve 12 disposed in the intake passage 11, and a fuel injection valve 13 for supplying fuel to the cylinder. In the combustion chamber of the internal combustion engine 10, the internal combustion engine output is obtained by burning the mixture of the intake air and the fuel injected from the fuel injection valve 13.

[0027] The crankshaft 18 of the internal combustion engine 10 is connected to a multi-stage automatic transmission 200 equipped with a torque converter 40 and a transmission mechanism 50.

[0028] The torque converter 40 includes a pump impeller 42P connected to the crankshaft 18 and a turbine impeller 42T connected to the input shaft 49 of the transmission mechanism 50. In this torque converter 40, torque is transmitted between the pump impeller 42P and the turbine impeller 42T via ATF (Automatic Transmission Fluid), which is a fluid. Furthermore, the torque converter 40 includes a lock-up clutch 45, the operating state of which varies between an engaged state directly connecting the pump impeller 42P and the turbine impeller 42T and a released state disengaging this engaged state.

[0029] The transmission mechanism 50 is a planetary gear type multi-stage transmission with a known structure, having multiple planetary gear mechanisms and multiple friction engagement elements 52, i.e., clutches and brakes, that are actuated hydraulically. Furthermore, by changing the engagement and disengagement states of these friction engagement elements 52, various gears are formed. In this embodiment, the engagement state of the friction engagement element 52 refers to the state in which power transmission is possible. Therefore, the state in which the friction engagement element 52 is not fully engaged and can slide is also included in the engagement state.

[0030] The friction engagement element 52 includes a starting engagement element 52s, which switches its operating state from a released state to an engaged state when the shift lever 300 (described later) is switched from a non-driving position to a driving position. The starting engagement element 52s is an engagement element that forms a first gear for forward movement and an engagement element that forms a reverse gear.

[0031] The output shaft of the transmission mechanism 50 is connected to the drive wheel 65 of the vehicle 500 via a differential gear 60.

[0032] The operation of the automatic transmission 200, including the operation of the clutch and brake of the transmission mechanism 50 and the operation of the lock-up clutch 45, is implemented by controlling the hydraulic circuit 90 that supplies working oil to the aforementioned mechanisms.

[0033] The control device 100 controls the internal combustion engine 10 and operates various operating parts of the internal combustion engine 10, such as the throttle valve 12 and the fuel injection valve 13, in order to control the torque, exhaust component ratio, and other parameters that are controlled by the engine. Additionally, the control device 100 controls the lock-up clutch 45 and the automatic transmission 200 and operates the hydraulic circuit 90 in order to control the hydraulic pressure that is controlled by the transmission.

[0034] Various controls of the internal combustion engine 10 and automatic transmission 200, etc., are performed by the control device 100 mounted on the vehicle 500.

[0035] The control device 100 includes a CPU 110 and a memory 120 storing control programs and data. Furthermore, by having the CPU 110 execute the program stored in the memory 120, various controls and processes described later are performed. Although not shown in the figures, the control device 100 is composed of multiple control units, such as a control unit for an internal combustion engine and a control unit for an automatic transmission.

[0036] When controlling the aforementioned control quantities, the control device 100 refers to the output signal Scr of the crankshaft angle sensor 70, which detects the rotation angle of the crankshaft 18, and the cooling water temperature THW of the internal combustion engine 10, detected by the water temperature sensor 71. Additionally, the control device 100 refers to the intake air volume GA of the internal combustion engine 10, detected by the air flow meter 72, and the accelerator pedal depressor amount, i.e., the accelerator operation amount ACCP, detected by the accelerator position sensor 73. Furthermore, the control device 100 refers to the vehicle speed SP of the vehicle 500, detected by the vehicle speed sensor 74, and the turbine speed Nt, detected by the turbine impeller 42T, detected by the speed sensor 75. Finally, the control device 100 refers to the hydraulic pressure Pat of the working oil supplied to the friction engagement element 52, detected by the hydraulic temperature sensor 76, and the temperature of the working oil, i.e., the oil temperature Toil, detected by the oil temperature sensor 77.

[0037] Furthermore, the control device 100 calculates the internal combustion engine speed NE based on the output signal Scr of the crankshaft angle sensor 70. Additionally, the control device 100 calculates the internal combustion engine load rate KL based on the internal combustion engine speed NE and the intake air volume GA.

[0038] The vehicle 500 includes a gear shift lever 300 that allows the driver to switch between a non-driving position and a driving position. A non-driving position refers to a position where the vehicle 500 is not in motion, such as the parking position (P) or neutral position (N). When the gear shift lever 300 is in the non-driving position, a non-driving gear is selected in the transmission mechanism 50. Conversely, a driving position refers to a position where the vehicle 500 is in motion, such as the drive position (D) or reverse position (R). When the gear shift lever 300 is in the driving position, a driving gear is selected in the transmission mechanism 50. Furthermore, a shift position sensor 310 is connected to the control device 100 to detect the operating position of the gear shift lever 300, i.e., the shift position SFT.

[0039] <On Torque Control of Internal Combustion Engines>

[0040] When the shift lever 300 is switched from the non-driving position to the driving position, the operating state of the starting engagement element 52s switches from the released state to the engaged state. During this switch, if the starting engagement element 52s begins to engage, the torque converter load torque begins to increase.

[0041] The torque converter load torque is as follows: That is, when the starting engagement element 52s begins to engage, the transmission torque capacity of the transmission mechanism 50 gradually increases. Therefore, in the torque converter 40, the load torque of the turbine impeller 42T, which resists the rotation of the pump impeller 42P, increases. The load torque of the turbine impeller 42T, which resists the rotation of the pump impeller 42P, is the aforementioned torque converter load torque. This torque converter load torque is a value representing the magnitude of the load acting on the internal combustion engine 10 from the drive system of the vehicle 500.

[0042] If the torque generated by the internal combustion engine 10 is excessive or insufficient relative to the increase in the torque converter load torque, the rotational variation of the internal combustion engine speed of the internal combustion engine 10 will occur.

[0043] Therefore, when the shift lever 300 is switched from a non-driving position to a driving position, the control device 100 performs torque control, for example, as follows.

[0044] In this torque control, feedback control is performed on the torque generated in the internal combustion engine 10, i.e., the internal combustion engine torque, in a manner that makes the internal combustion engine speed NE of the internal combustion engine 10 a target speed NET. The target speed NEt is the target value of the internal combustion engine speed NE when the internal combustion engine 10 is idling. The target speed NEt value, i.e., the target value NEn, when the shift lever 300 is in the non-driving position is a higher speed than the target speed NEt value, i.e., the target value NED, when the shift lever 300 is in the driving position. Furthermore, when the control start flag F (described later) is turned on, the gradual value that causes the target value NEn to gradually change towards the target value NED is set as the target speed NEt. Based on the target speed NEt set in this way, the control device 100 calculates the basic torque Tb as a feedforward term. In addition, based on the deviation between the target speed NEt and the actual internal combustion engine speed NE, the feedback gain (hereinafter referred to as FB gain) M, etc., the control device 100 calculates the torque value, i.e., the FB correction amount Tfb, as a feedback term. Then, the control device 100 substitutes the value obtained by adding the basic torque Tb to the FB correction amount Tfb into the required torque Td. The control device 100 then controls the intake air quantity, fuel injection quantity, etc. of the internal combustion engine 10 in order to obtain the required torque Td. Furthermore, when the FB correction amount Tfb is positive, the basic torque Tb is corrected on the increasing side. On the other hand, when the FB correction amount Tfb is negative, the basic torque Tb is corrected on the decreasing side.

[0045] Furthermore, in this torque control, when the rate of increase of the torque converter load torque, i.e., the rate of increase of the load torque LTS, is faster, the control device 100 performs a process that increases the correction amount of the internal combustion engine torque generated in the internal combustion engine 10 towards the increasing side, compared to when it is slower. By performing this process, the decrease in internal combustion engine speed caused by the increase of the torque converter load torque can be suppressed, and therefore, for example, engine stalling can be suppressed. In addition, such processing can be implemented appropriately. For example, when the rate of increase of the load torque LTS is faster, the value of the basic torque Tb can be set to a larger value compared to when it is slower. Alternatively, when the rate of increase of the load torque LTS is faster, the gain can be changed to increase the correction amount Tfb of the FB towards the side that increases the internal combustion engine torque, compared to when it is slower.

[0046] If the timing of the start of such torque control deviates from the timing of the engagement of the starting engagement element 52s, an excess or deficiency of internal combustion engine torque relative to the increase in torque converter load torque will occur. Therefore, it may be impossible to suppress the rotational fluctuation of the internal combustion engine 10 that occurs when the starting engagement element engages.

[0047] Therefore, the control device 100 suppresses the occurrence of such undesirable conditions by performing the processes described below.

[0048] <Control Start Flag Setting Processing>

[0049] exist Figure 2 The diagram illustrates the process by which the control device 100 performs a process at a predetermined cycle in order to set the aforementioned control start flag F. Furthermore, the following uses numbers beginning with "S" to indicate the step numbers of each process.

[0050] At the start of this process, the control device 100 determines whether the vehicle 500 is in a stopped state (S100). In the process of S100, for example, if the vehicle speed SP is below a predetermined threshold, the control device 100 determines that the vehicle 500 is in a stopped state.

[0051] If it is determined that the vehicle 500 is in a stationary state (S100: "Yes"), the control device 100 determines whether the shift position SFT is in a driving position (S110).

[0052] If the shift position SFT is determined to be in the driving position (S110: "Yes"), the control device 100 determines whether the shift position SFT was in the non-driving position when this process was last executed (S120). In the process of S120, if the determination is yes, the shift lever 300 switches from the non-driving position to the driving position during the period from the last execution of this process to the current execution.

[0053] In the process of S120, if the determination is positive, the control device 100 determines whether the control start flag F is off (S130). The initial value of the control start flag F is off. Furthermore, if the control start flag F is on, the torque control is implemented; otherwise, if the control start flag F is off, the torque control is stopped.

[0054] In the processing of S130, if it is determined that the control start flag F is off (S130: "Yes"), the control device 100 executes the increment counting of the counter DC (S140). The counter DC is a value representing the elapsed time since the shift lever 300 switched from the non-driving position to the driving position.

[0055] On the other hand, in the above-mentioned S120 process, if the determination is negative, the control device 100 performs initialization (S150) to set the value of the counter DC to "0".

[0056] Next, during the processing in S150 described above, the control device 100 obtains the target time TCLt (S160). The target time TCLt is the time from when the shift lever 300 switches from the non-driving position to the driving position until the starting engagement element begins to engage after 52 seconds. The control unit for the automatic transmission sets the target time TCLt based on oil temperature, etc. Furthermore, the control unit for the automatic transmission controls the hydraulic system, such as the throttle, in order to obtain the target time TCLt. In this processing in S160, the control unit for the internal combustion engine obtains the target time TCLt calculated by the control unit for the automatic transmission.

[0057] Next, when performing the above-described S140 process or the above-described S160 process, the control device 100 obtains hydraulic Pat (S170) of the working oil supplied to the starting engagement element 52s.

[0058] Next, the control device 100 calculates the hydraulic change PatH (S180). The hydraulic change PatH is obtained by subtracting the hydraulic Pat obtained in the previous execution cycle from the hydraulic Pat obtained in the processing of S170 in the current execution cycle. Furthermore, the hydraulic Pat used in the calculation of the hydraulic change PatH is preferably a value that has been smoothed from the detection value of the hydraulic sensor 76.

[0059] Next, the control device 100 determines whether any one of the following conditions (A) and (B) is true (S190).

[0060] Condition A: The current value of the counter DC is above the target time TCLt mentioned above.

[0061] Condition B: The hydraulic change PatH is greater than or equal to the preset value PatHref. The preset value PatHref is the hydraulic change PatH when the starting engagement element begins to engage after 52 seconds, and it is a pre-set appropriate value.

[0062] In the process of S190, if either condition (A) or condition (B) is determined to be true, the control device 100 changes the control start flag F from off to on (S200). When the control start flag F is set to on through the process of S200, the above-mentioned torque control begins.

[0063] On the other hand, in the process of S100 or S110 described above, if the determination is negative, the control device 100 sets the control start flag F to off (S220).

[0064] Furthermore, if the processing of S200 is performed, or if the processing of S220 is performed, or if the processing of S130 is determined to be negative, or if the processing of S190 is determined to be negative, the control device 100 temporarily terminates the processing.

[0065] <Calculation and processing of the rate of increase in load torque>

[0066] exist Figure 3 The diagram illustrates the process by which the control device 100 performs a predetermined cycle to calculate the rate of increase of the load torque of the torque converter used in implementing the above-described torque control.

[0067] When this process begins, the control device 100 determines whether the control start flag F is turned on (S300).

[0068] When the control start flag F is determined to be on (S300: "Yes"), the control device 100 acquires the turbine target change speed NtHt and the aforementioned hydraulic change amount PatH (S310). The turbine target change speed NtHt is the target change speed of the turbine impeller 42T. That is, it is the target change amount of the turbine speed Nt per unit time. The control unit for the automatic transmission sets the turbine target change speed NtHt so that the change speed of the turbine speed Nt during the engagement and propulsion process of the starting engagement element 52s is an appropriate value. Then, the control unit for the automatic transmission controls the hydraulic Pat and the like in a manner that obtains the turbine target change speed NtHt. In this process of S310, the control unit for the internal combustion engine acquires the turbine target change speed NtHt calculated by the control unit for the automatic transmission.

[0069] Next, the control device 100 calculates the first torque increase rate LTS1 (S320) based on the turbine target change rate NtHt. The first torque increase rate LTS1 is the rate of increase of the torque converter load torque obtained by converting the turbine target change rate NtHt using an appropriate model formula, etc.

[0070] Next, the control device 100 calculates the second torque increase rate LTS2 (S330) based on the obtained hydraulic change PatH. The second torque increase rate LTS2 is the rate of increase of the torque converter load torque obtained by converting the hydraulic change PatH using an appropriate model formula, etc.

[0071] Next, the control device 100 determines whether the first torque increase rate LTS1 is greater than or equal to the second torque increase rate LTS2 (S340).

[0072] Furthermore, if it is determined that the first torque increase rate LTS1 is greater than or equal to the second torque increase rate LTS2 (S340: "Yes"), the control device 100 substitutes the first torque increase rate LTS1 into the load torque increase rate LTS (S350).

[0073] On the other hand, if it is determined that the first torque increase rate LTS1 is not greater than the second torque increase rate LTS2 (S340: "No"), the control device 100 substitutes the second torque increase rate LTS2 into the load torque increase rate LTS (S360). By executing each of the above processes S340, S350 and S360, when the first torque increase rate LTS1 and the second torque increase rate LTS2 are different, the larger value is substituted into the load torque increase rate LTS.

[0074] Furthermore, if the processing of S350 is performed, or if the processing of S360 is performed, or if the result is negative in the processing of S300, the control device 100 temporarily terminates the processing.

[0075] <FB Gain Correction Processing>

[0076] exist Figure 4 The diagram illustrates the process by which the control device 100 executes processing according to a predetermined cycle. This processing includes correcting the FB gain M used when implementing the torque control described above. Furthermore, when the value of FB gain M is greater than "1", the larger the value of FB gain M, the greater the correction amount for increasing the internal combustion engine torque. On the other hand, when the value of FB gain M is less than "1", the smaller the value of FB gain M, the greater the correction amount for decreasing the internal combustion engine torque.

[0077] At the start of this process, the control device 100 calculates the current FB gain M (S400). In the process of S400, the control device 100 calculates the value obtained by dividing the currently set target speed NEt by the current internal combustion engine speed NE. Then, the calculated value is substituted into the current FB gain M.

[0078] Next, the control device 100 determines whether the control start flag F is on (S410). And, if it is determined that the control start flag F is on (S410: "Yes"), the control device 100 determines whether the current internal combustion engine speed NE is above the target speed NEt (S420).

[0079] If the current internal combustion engine speed NE is determined to be higher than or equal to the target speed NEt (S420: "Yes"), the control device 100 calculates a first coefficient K1 based on the speed difference ΔNE (S430). The speed difference ΔNE is a value obtained by subtracting the current internal combustion engine speed NE from the target speed NEt. The first coefficient K1 is a value of "1" or higher, and is variably set such that the larger the absolute value of the speed difference ΔNE, the larger the value of the first coefficient K1 becomes.

[0080] Next, during the execution of process S430, control device 100 calculates the second coefficient K2 based on the elapsed time TE (S440). The elapsed time TE is the time that control device 100 begins measuring when the process of S200 is executed and the control start flag F is set to on, and it is a value equivalent to the elapsed time since the start of the torque control. The second coefficient K2 is a value of "1" or higher, and is variably set such that the shorter the elapsed time TE, the less the convergence of the internal combustion engine speed NE to the target speed NEt is promoted, and the larger the value of the second coefficient K2 becomes.

[0081] Next, the control device 100 determines whether the first coefficient K1 is greater than or equal to the second coefficient K2 (S450).

[0082] Furthermore, if it is determined that the first coefficient K1 is greater than or equal to the second coefficient K2 (S450: "Yes"), the control device 100 substitutes the first coefficient K1 into the response coefficient K (S460).

[0083] On the other hand, if it is determined that the first coefficient K1 is not greater than the second coefficient K2 (S450: "No"), the control device 100 substitutes the second coefficient K2 into the response coefficient K (S470). By executing each of the above processes S450, S460 and S470, when the values ​​of the first coefficient K1 and the second coefficient K2 are different, the larger value is substituted into the response coefficient K.

[0084] Next, the control device 100 corrects the FB gain M by multiplying the FB gain M calculated in the above-described S400 process with the response coefficient K (S480). The control device 100 uses the FB gain M corrected in the S480 process to implement the above-described torque control.

[0085] In the above S420 process, when the determination is positive, since the current internal combustion engine speed NE is above the target speed NEt, the value of FB gain M calculated in the S400 process is a value of "1" or less, which is basically a value that corrects the internal combustion engine torque towards the reduction side.

[0086] Here, the aforementioned first coefficient K1 is a value of "1" or higher, and is variably set such that the larger the absolute value of the speed difference ΔNE, the larger the value of the first coefficient K1 becomes. Therefore, when the first coefficient K1 is substituted into the response coefficient K, the larger the absolute value of the speed difference ΔNE, the larger the value of the corrected FB gain M becomes. Therefore, by reducing the amount of correction that shifts the internal combustion engine torque towards the reduction side, the correction of the internal combustion engine torque towards the reduction side can be suppressed.

[0087] On the other hand, the aforementioned second coefficient K2 is also a value of "1" or higher, and is variably set such that the value of the second coefficient K2 increases as the elapsed time TE becomes shorter. Therefore, when the second coefficient K2 is substituted into the response coefficient K, the shorter the elapsed time TE, the larger the value of the corrected FB gain M becomes. Therefore, by reducing the amount of correction that shifts the internal combustion engine torque towards the reduction side, the correction of the internal combustion engine torque towards the reduction side can be suppressed.

[0088] In the above-described S420 process, if the determination is negative (S420: "No"), that is, if the current internal combustion engine speed NE is lower than the target speed NET, the control device 100 determines whether the absolute value of the speed difference ΔNE exceeds a preset value ΔNEref (S490). The preset value ΔNEref is the absolute value of the speed difference ΔNE that could potentially cause the engine to stall, and it is a pre-set appropriate value.

[0089] If the absolute value of the speed difference ΔNE is determined to exceed the preset value ΔNEref (S490: "Yes"), the control device 100 determines whether the current coolant temperature THW is less than the preset value THWref (S500). The preset value THWref is the coolant temperature THW at which engine stall may occur, and it is a pre-set appropriate value.

[0090] If the current coolant temperature THW is determined to be less than the preset value THWref (S500: "Yes"), the control device 100 sets the transmission stop requirement flag FS to on (S510). When the transmission stop requirement flag FS is set to on, the engagement action of the starting engagement element 52s is prohibited, and the starting engagement element 52s is temporarily released, thereby suppressing engine stalling.

[0091] Furthermore, if the process described in S480 is executed, or if the process described in S510 is executed, the control device 100 temporarily terminates the process. Additionally, if the process described in S410 is deemed negative, or if the process described in S490 is deemed negative, or if the process described in S500 is deemed negative, the control device 100 temporarily terminates the process.

[0092] <The function of this implementation method>

[0093] exist Figure 5 The diagram shows the shift of values ​​as the operating state of the starting engagement element 52s switches from the released state to the engaged state. Figure 5 (a) shows the shift of the FB correction Tfb. Figure 5 (b) shows the shifts in internal combustion engine speed NE, target speed NEt, and turbine speed Nt. Figure 5 (c) shows the shift of the control start flag F. Figure 5 (d) shows the shift of the shift position SFT. Figure 5 (e) shows the shift in torque converter load torque.

[0094] If the shift position is switched from a non-driving position (e.g., N position) to a driving position (e.g., D position) at time t1, hydraulic supply to the starting engagement element 52s begins, thereby changing the operating state of the starting engagement element 52s from the released state to the engaged state.

[0095] If the engagement element is engaged for 52 seconds at time t2, the turbine speed Nt decreases, and the torque converter load torque begins to increase. Furthermore, at time t2, since either condition (A) or condition (B) is met, the control start flag F changes from off to on. Therefore, the aforementioned torque control begins at time t2.

[0096] When torque control begins, the target speed NEt gradually changes from the aforementioned target value NEn towards the aforementioned target value NED. Furthermore, feedback control of the internal combustion engine torque is performed to ensure that the actual internal combustion engine speed NE matches the target speed NEt. Additionally, during torque control, the rate of increase of the torque converter load torque, i.e., the load torque increase rate LTS, is calculated. Based on this calculated load torque increase rate LTS, the internal combustion engine torque is corrected. Specifically, when the load torque increase rate LTS is faster, compared to when it is slower, a process is performed that increases the correction amount of the internal combustion engine torque towards the increasing side, thereby suppressing fluctuations in the internal combustion engine speed NE caused by the torque converter load torque.

[0097] Furthermore, after time t2, when the internal combustion engine speed NE is above the target speed NEt, by performing a correction on the FB gain M based on the aforementioned response coefficient K, the value of the FB correction amount Tfb is suppressed from increasing towards the side that reduces the internal combustion engine torque. Therefore, the decrease in internal combustion engine speed NE towards the target speed NEt becomes slower. Thus, it is possible to suppress engine stalling when the starting engagement element 52s is engaged.

[0098] Then, at time t3, when the engagement of the starting engagement element is completed after 52 seconds, the decrease in turbine speed Nt stops, and the increase in torque converter load torque also stops. Then, after time t3, the internal combustion engine speed NE converges to the target speed NEt, which is set as the target value NED.

[0099] <Effects of this implementation method>

[0100] (1) When the hydraulic pressure of the working oil supplied to the starting engagement element 52s increases, the working state of the starting engagement element 52s switches from the released state to the engaged state. Therefore, after the shift lever 300 switches from the non-driving position to the driving position, when the change in hydraulic pressure of the working oil supplied to the starting engagement element 52s is greater than or equal to a preset value, it can be presumed that the working state of the starting engagement element 52s changes from the released state to the engaged state.

[0101] Furthermore, in this embodiment, a target time TCLt is set from the time the gear shift lever 300 switches from the non-driving position to the driving position until the starting engagement element 52s begins to engage. In this case, at the point when the target time TCLt has elapsed, it can be presumed that the operating state of the starting engagement element 52s has changed from the released state to the engaged state.

[0102] Therefore, after the shift lever 300 is switched from the non-driving position to the driving position, if either condition (A) or condition (B) is met, the control device 100 sets the control start flag F to on and begins the execution of the torque control. Thus, torque control of the internal combustion engine 10, taking into account the rate of increase in torque converter load torque, can begin in conjunction with the engagement start timing of the starting engagement element 52s. Therefore, rotational fluctuations of the internal combustion engine 10 that occur when the starting engagement element 52s engages can be suppressed.

[0103] (2) When switching the operating state of the starting engagement element 52s from the released state to the engaged state, if a target rate of change of turbine speed Nt is set, this target rate of change is related to the rate of increase of torque converter load torque. Furthermore, the change in hydraulic pressure supplied to the starting engagement element 52s is related to the rate of increase of torque converter load torque. Therefore, the control device 100 obtains the target rate of change of turbine speed Nt, i.e., the turbine target rate of change NtHt, and calculates the rate of increase of torque converter load torque, i.e., the first torque increase rate LTS1, based on the turbine target rate of change NtHt. Additionally, the control device 100 calculates the rate of increase of torque converter load torque, i.e., the second torque increase rate LTS2, based on the change in hydraulic pressure supplied to the starting engagement element 52s, i.e., the hydraulic pressure change PatH. Then, the control device 100 substitutes the larger of the first torque increase rate LTS1 and the second torque increase rate LTS2 into the load torque increase rate LTS. Therefore, compared to the case where the smaller of the first torque increase rate LTS1 and the second torque increase rate LTS2 is substituted into the load torque increase rate LTS, the correction amount of the internal combustion engine torque towards the increase side after the above-described torque control of the internal combustion engine 10 is greater. Therefore, it is possible to suppress engine stalling caused by insufficient torque of the internal combustion engine 10 relative to the load torque increase rate LTS.

[0104] (3) When the internal combustion engine speed NE is higher than or equal to the target speed NEt, the internal combustion engine torque is corrected towards the reduction side through the torque control described above. However, if this torque correction towards the reduction side is excessive, engine stalling may occur when the starting engagement element 52s engages. In this case, when the internal combustion engine speed NE is higher than or equal to the target speed NEt, the control device 100 performs the above-described correction of the FB gain M, thereby suppressing the correction of the internal combustion engine torque towards the reduction side based on torque control. Therefore, engine stalling can be suppressed when the starting engagement element 52s engages.

[0105] <Variation Example>

[0106] Furthermore, this embodiment can be modified and implemented as follows. This embodiment and the following variations can be combined and implemented with each other within the scope of technical inconsistency.

[0107] • When the starting engagement element 52s switches from the released state to the engaged state, the rotational speed of the turbine impeller 42T connected to the input shaft of the transmission mechanism 50 increases. Therefore, after the shift lever 300 switches from the non-driving position to the driving position, if the change in the rotational speed of the turbine impeller 42T is greater than or equal to a preset value, it can be presumed that the operating state of the starting engagement element 52s has changed from the released state to the engaged state.

[0108] Therefore, in the above embodiment, the determination of whether to set the control start flag F to on is based on the hydraulic change PatH, but the determination can also be based on the change in turbine speed Nt.

[0109] In this variation, the following is omitted. Figure 2 The series of processes shown includes S170, S180, and S190. Furthermore, instead of the omitted processes described above, it is possible to execute... Figure 6 The specific implementations of S600, S610 and S620 shown are described below.

[0110] like Figure 6 As shown, after executing either the process of S140 or the process of S160 described above, the control device 100 executes the process of S600.

[0111] In the S600 process, the control device 100 obtains the turbine speed Nt.

[0112] Next, the control device 100 calculates the speed change NtH (S610). The speed change NtH is obtained by subtracting the turbine speed Nt obtained in the previous execution cycle from the turbine speed Nt obtained in the processing of S600 in the current execution cycle. Furthermore, the turbine speed Nt used in the calculation of the speed change NtH is preferably a value that has been smoothed from the detection value of the speed sensor 75.

[0113] Next, the control device 100 determines whether any of the above condition (A) and the following condition (C) are true (S620).

[0114] Condition A: The current value of the counter DC is above the target time TCLt mentioned above.

[0115] Condition C: The speed change NtH is greater than or equal to the preset value NtHref. The preset value NtHref is the speed change NtH when the starting engagement element begins to engage after 52 seconds, and it is a pre-set appropriate value.

[0116] In the processing of S620, if either condition (A) or condition (C) is determined to be true, the control device 100 changes the control start flag F from off to on (S200). When the control start flag F is set to on through the processing of S200, the above-mentioned torque control begins.

[0117] On the other hand, in the above-mentioned S620 process, if the determination is negative, the control device 100 temporarily terminates. Figure 6 The series of processes shown.

[0118] In this modified example, torque control of the internal combustion engine 10, which takes into account the rate of increase in torque converter load torque, can also be initiated in accordance with the engagement start timing of the starting engagement element 52s. Therefore, rotational fluctuations of the internal combustion engine 10 that occur when the starting engagement element 52s engages can be suppressed.

[0119] The change in the rotational speed of the turbine impeller 42T is related to the rate of increase of the torque converter load torque. Therefore, in the above embodiment, the second torque increase rate LTS2 was calculated based on the hydraulic pressure change PatH, but it can also be calculated based on the change in turbine rotational speed Nt.

[0120] In this variation, the following is omitted. Figure 3 The series of processes shown includes S310 and S330. Furthermore, instead of the omitted processes described above, it is possible to execute... Figure 7 The specific implementations of the S700 and S710 processes shown are as follows.

[0121] like Figure 7 As shown, in the above-mentioned S300 process, if the determination is positive, the control device 100 obtains the above-mentioned turbine target change speed NtHt and the above-mentioned speed change amount NtH (S700).

[0122] Next, the control device 100 performs the processing described in S320 above to calculate the first torque increase rate LTS1 based on the turbine target change rate NtHt.

[0123] Next, the control device 100 calculates the second torque increase rate LTS2 (S710) based on the obtained speed change NtH. The second torque increase rate LTS2 here is the rate of increase of the torque converter load torque obtained by converting the speed change NtH using an appropriate model formula, etc.

[0124] When performing the processing of S710, the control device 100 substitutes the larger of the values ​​of the first torque increase rate LTS1 and the second torque increase rate LTS2 into the load torque increase rate LTS by performing the processing after S340.

[0125] Therefore, compared to the case where the smaller of the first torque increase rate LTS1 and the second torque increase rate LTS2 is substituted into the load torque increase rate LTS, in this modified example, the amount of correction to the increase side of the internal combustion engine torque after the aforementioned torque control of the internal combustion engine 10 is greater. Therefore, it is possible to suppress engine stalling caused by insufficient torque of the internal combustion engine 10 relative to the load torque increase rate LTS.

[0126] Alternatively, if at least one of the above conditions (A), (B), and (C) is met, the control start flag F is set to ON.

[0127] The increase rate of the torque converter load torque, i.e., the first torque increase rate LTS1, is calculated based on the turbine target change rate NtHt. Additionally, the increase rate of the torque converter load torque is calculated based on the hydraulic pressure change PatH. Furthermore, the increase rate of the torque converter load torque is calculated based on the speed change NtH. Alternatively, the maximum value among these three calculated increases in torque converter load torque can be substituted into the load torque increase rate LTS.

[0128] The load torque increase rate LTS was calculated based on the above-mentioned turbine target change rate NtHt, the above-mentioned hydraulic change amount PatH, and the above-mentioned speed change amount NtH. However, the load torque increase rate LTS can also be calculated based on other parameters.

[0129] • Can also be omitted Figure 4 The processing related to the correction of FB gain M is shown. In this case, effects other than those mentioned in (3) can also be obtained.

[0130] • Can also be omitted Figure 4 The processing shown relates to the setting of the shift stop requirement flag FS.

Claims

1. A control device for an internal combustion engine, the internal combustion engine being mounted in a vehicle, the vehicle having an automatic transmission and a shift lever, the automatic transmission comprising: a transmission mechanism having a plurality of friction engaging elements; and a torque converter having a pump impeller connected to an output shaft of the internal combustion engine and a turbine impeller connected to an input shaft of the transmission mechanism, the shift lever being operated to switch between a non-driving position and a driving position, the friction engaging elements having a starting engaging element, wherein when the shift lever switches from the non-driving position to the driving position, the starting engaging element switches its operating state from a released state to an engaged state, wherein... When the load torque of the turbine impeller resisting the rotation of the pump impeller is set as the torque converter load torque, and the rate of increase of the torque converter load torque is set as the rate of increase of the load torque, the control device of the internal combustion engine performs feedback control on the internal combustion engine torque generated by the internal combustion engine in a manner that makes the internal combustion engine speed a target speed. Furthermore, when the rate of increase of the load torque is faster, compared to when it is slower, torque control is implemented to increase the correction amount of the internal combustion engine torque towards the increasing side. The control device of the internal combustion engine performs the following processing: Obtain the target time from when the shift lever switches from the non-driving position to the driving position until the starting engagement element begins to engage; and After the shift lever is switched from the non-driving position to the driving position, torque control begins if either of the following conditions is met: the change in hydraulic pressure of the working oil supplied to the starting engagement element is greater than or equal to a preset value, or the target time has elapsed since the shift lever was switched from the non-driving position to the driving position.

2. A control device for an internal combustion engine, the internal combustion engine being mounted in a vehicle, the vehicle having an automatic transmission and a shift lever, the automatic transmission comprising: a transmission mechanism having a plurality of friction engaging elements; and a torque converter having a pump impeller connected to the output shaft of the internal combustion engine and a turbine impeller connected to the input shaft of the transmission mechanism, the shift lever being operated to switch between a non-driving position and a driving position, the friction engaging elements having a starting engaging element, wherein when the shift lever switches from the non-driving position to the driving position, the starting engaging element switches its operating state from a released state to an engaged state, wherein... When the load torque of the turbine impeller resisting the rotation of the pump impeller is set as the torque converter load torque, and the rate of increase of the torque converter load torque is set as the rate of increase of the load torque, the control device of the internal combustion engine performs feedback control on the internal combustion engine torque generated by the internal combustion engine in a manner that makes the internal combustion engine speed a target speed. Furthermore, when the rate of increase of the load torque is faster, compared to when it is slower, torque control is implemented to increase the correction amount of the internal combustion engine torque towards the increasing side. The control device of the internal combustion engine performs the following processing: Obtain the target time from when the shift lever switches from the non-driving position to the driving position until the starting engagement element begins to engage; and After the shift lever is switched from the non-driving position to the driving position, torque control begins if either of the following conditions is met: the change in the speed of the turbine impeller is greater than or equal to a preset value, or the target time has elapsed since the shift lever was switched from the non-driving position to the driving position.

3. The control device for an internal combustion engine according to claim 1 or 2, wherein, The control device of the internal combustion engine performs the following processing: Obtain the target rate of change of the turbine impeller speed, and calculate the rate of increase of the torque converter load torque, i.e., the first torque increase rate, based on the target rate of change; Based on the change in hydraulic pressure supplied to the starting engagement element, the rate of increase in the torque converter load torque, i.e., the second torque increase rate, is calculated; and The larger of the first torque increase rate and the second torque increase rate is set as the load torque increase rate.

4. The control device for an internal combustion engine according to claim 1 or 2, wherein, The control device of the internal combustion engine performs the following processing: Obtain the target rate of change of the turbine impeller speed, and calculate the rate of increase of the torque converter load torque, i.e., the first torque increase rate, based on the target rate of change; Based on the change in the turbine impeller speed, the rate of increase in the torque converter load torque, i.e., the second torque increase rate, is calculated; and The larger of the first torque increase rate and the second torque increase rate is set as the load torque increase rate.

5. The control device for an internal combustion engine according to claim 1 or 2, wherein, When the internal combustion engine speed is above the target speed, the control device of the internal combustion engine performs a process to suppress the correction of the internal combustion engine torque to the reduction side based on the torque control.

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