JP2008138543A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine, reducing shocks generated in downshifting and making a rise of torque steep during a period from the starting of downshifting to the completion thereof. <P>SOLUTION: This control device is applied to the internal combustion engine 2 provided with an automatic transmission 5, estimates shift timing that downshifting is completed when downshifting is performed by the automatic transmission 5, estimates a difference in the output torque of the automatic transmission 5 produced before and after the downshifting, calculates based on the difference in the output torque an engine demand torque for the internal combustion engine suppressing the resonance of the internal combustion engine 2 with a driving system in the shift timing, and controls a fuel injection amount so that the engine demand torque is output from the crankshaft of the internal combustion engine 1, provided that the shift timing reaches. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device applied to an internal combustion engine provided with an automatic transmission that is connected to an output shaft of the internal combustion engine and can be switched to a plurality of transmission gear ratios having different sizes.

  As a control device for an internal combustion engine equipped with an automatic transmission, it is large when the output rotation speed of the automatic transmission is multiplied by the speed ratio after downshifting, and the change rate of the load of the internal combustion engine is large, and the change rate is small. There has been known one that performs torque reduction control of an internal combustion engine from when a value obtained by subtracting a predetermined value that is sometimes set smaller than the rotational speed of the internal combustion engine (Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP-A-6-135263 JP 2003-41987 JP-A-8-232696

  The torque reduction control of Patent Document 1 alleviates a shock that occurs during a downshift by temporarily reducing the torque of the internal combustion engine at the timing described above and then returning the torque to the original state after a predetermined time. The shock that occurs during the downshift is thought to be mainly due to the resonance of the drive system of the internal combustion engine that accompanies the torque change during the downshift. Therefore, the torque of the internal combustion engine may be controlled to the extent that the resonance can be suppressed. However, since the torque reduction control of Patent Document 1 does not consider such resonance, the torque may be excessively reduced during the downshift. As a result, although the shock at the time of downshift can be alleviated, the rise of torque from the start to the end of downshift may be dull.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for an internal combustion engine that can reduce shocks that occur during downshifting and that can sharply increase the torque from the start to the completion of downshifting.

  The control apparatus for an internal combustion engine of the present invention is applied to an internal combustion engine provided with an automatic transmission that is connected to an output shaft of the internal combustion engine and can be switched to a plurality of speed ratios having different sizes, and the speed ratio is small. A shift timing estimating means for estimating a shift timing at which the downshift is completed when a downshift to be switched from a large to a large one is performed in the automatic transmission; and an automatic transmission that can occur before and after the downshift. Engine required torque calculation for calculating the engine required torque of the internal combustion engine capable of suppressing resonance between the output torque difference estimating means for estimating the output torque difference and the drive system of the internal combustion engine at the shift timing based on the output torque difference And the engine required torque calculated by the engine required torque calculating means on condition that the shift timing has been reached. There By providing the, and engine control means for controlling the internal combustion engine so as to be outputted from the output shaft of the internal combustion engine, to solve the problems described above (claim 1).

  According to the control device of the present invention, on the condition that the shift timing is reached, the engine required torque that can suppress resonance with the drive system of the internal combustion engine is output from the internal combustion engine, and the engine required torque is before and after the downshift. It is calculated based on the output torque difference that can occur in Therefore, it is possible to reduce the shock that occurs during the downshift, and it is possible to prevent the output torque of the internal combustion engine from being excessively reduced for the purpose of reducing the shock. This makes it possible to sharpen the torque rise from the start to the end of the downshift while reducing the shock that occurs during the downshift.

  In one aspect of the control device of the present invention, the automatic transmission includes a pump connected to the output shaft of the internal combustion engine and a torque converter including a turbine combined with the pump. The shift timing estimator coupled to the output shaft, in the process from the start to the completion of the downshift, and a target rotational speed obtained by multiplying the output rotational speed of the automatic transmission by the speed ratio after the downshift, and the A margin rotation speed prediction means for predicting a margin rotation speed given as a difference from the turbine rotation speed of the turbine in consideration of respective temporal changes of the target rotation speed and the turbine rotation speed, and the margin rotation speed prediction means, Shift timing specifying means for specifying, as the shift timing, a timing at which the predicted marginal rotation speed becomes a predetermined value or less; May be provided (claim 2). In the process from the start to the end of the downshift, the surplus rotational speed gradually decreases, and when the downshift is completed, the rotational speed of the turbine coincides with the output rotational speed of the transmission. According to this aspect, since the surplus rotational speed is predicted in consideration of the respective temporal changes of the target rotational speed and the rotational speed of the turbine, the shift timing can be specified accurately. The predetermined value according to this aspect may be set as appropriate. For example, zero may be set as the predetermined value.

In this aspect, the margin rotation speed prediction means is configured to sequentially predict the margin rotation speed at the calculation timing of a predetermined cycle, and the target rotation speed at the current calculation timing is NoSft, The rotation speed of the turbine at the calculation timing is Nt, the time change from the previous calculation timing of the target rotation speed to the current calculation timing is ΔNoSft, and the time from the previous calculation timing of the turbine rotation speed to the current calculation timing When a change is ΔNt, a coefficient of 1 or more that is set to a larger value as the load of the internal combustion engine is larger is α, and the marginal rotation speed is Nmarg, the following formula is given: Nmarg = NoSft−Nt−α (ΔNt−ΔNoSft)
The marginal rotation speed may be predicted by (Claim 6). In this case, since the time change of the target rotational speed and the turbine rotational speed until the next calculation timing is set by the load of the internal combustion engine, the shift timing can be specified more accurately.

  In one aspect of the control device of the present invention, the control device further includes a resonance frequency storage unit that stores a resonance frequency of the drive system for each of the gear ratios, and the engine required torque calculation unit includes the gear ratio at the downshift gear ratio. The engine required torque may be calculated based on the stored contents of the resonance frequency storage means so that a component corresponding to the resonance frequency is removed. According to this aspect, since the component corresponding to the resonance frequency after the downshift is removed from the engine required torque, the shock at the time of downshift can be reduced without excessively reducing the engine required torque.

  It is sufficient if a component corresponding to the resonance frequency component is removed in the process of calculating the engine required torque, and the removal method may be adopted as appropriate. For example, the engine required torque calculating means includes a transmission required torque calculating means for calculating a transmission required torque of the automatic transmission corresponding to the output torque difference, and the transmission calculated by the transmission required torque calculating means. Conversion means for converting the required torque into the engine required torque, wherein the transmission required torque calculation means is configured to remove the component corresponding to the resonance frequency in the gear ratio after the downshift. The transmission required torque may be calculated based on the stored contents of the storage means. Further, the transmission request torque calculation means calculates a change amount of the transmission request torque by removing a component corresponding to the resonance frequency in the gear ratio after the downshift from the output torque difference, and the change amount May be calculated by adding to the current output torque of the transmission. Similarly to the above, these aspects can reduce the shock at the time of downshift without excessively reducing the engine required torque.

  In one aspect of the control device of the present invention, the output torque difference estimating means multiplies the engine output torque output from the output shaft of the internal combustion engine by the difference in the gear ratio before and after the downshift. The output torque difference may be estimated (claim 7). In this case, the difference between the gear ratios before and after the downshift can be easily obtained if the respective gear ratios before and after the downshift are known. There is.

  As described above, according to the present invention, on the condition that the shift timing has been reached, the engine required torque that can suppress resonance with the drive system of the internal combustion engine is output from the internal combustion engine, and the engine required torque is reduced. It is calculated based on the output torque difference that can occur before and after the shift. Therefore, it is possible to reduce the shock that occurs during the downshift, and it is possible to prevent the output torque of the internal combustion engine from being excessively reduced for the purpose of reducing the shock. As a result, the shock generated during the downshift can be reduced, and the torque rise from the start to the end of the downshift can be sharpened.

(First form)
FIG. 1 schematically shows a vehicle equipped with an internal combustion engine to which the control device of the present invention is applied. An internal combustion engine 2 is mounted on the vehicle 1 as a driving power source. The internal combustion engine 1 is configured as an in-line four-cylinder gasoline engine, and an automatic transmission 5 is connected to a crankshaft 3 as an output shaft via a torque converter 4. The torque converter 4 is a well-known one having a pump 4a connected to the crankshaft 3 and a turbine 4b connected to the input shaft 6 of the automatic transmission 5 in combination with the pump 4a. The automatic transmission 5 is configured to be switchable to a plurality of gear ratios having different sizes, and is switched to an appropriate gear ratio according to the traveling state of the vehicle 1 and the operating state of the internal combustion engine 2. The automatic transmission 5 shown in the figure has a gear ratio of 4 forward speeds and 1 reverse speed. The rotation of the output shaft 7 of the automatic transmission 5 is transmitted to the drive wheels 10 via the differential device 8.

  The internal combustion engine 2 and the automatic transmission 5 are controlled by an engine control unit (ECU) 20. The ECU 20 is configured as a computer including a microprocessor and peripheral devices such as ROM and RAM necessary for its operation. The ECU 20 outputs an engine rotation speed sensor 21 that outputs a signal corresponding to the rotation speed of the internal combustion engine 2, that is, the rotation speed of the crankshaft 3, and a signal corresponding to the amount of operation of the accelerator pedal by the driver, that is, the accelerator opening. The accelerator opening sensor 22, the turbine rotational speed sensor 23 for outputting a signal corresponding to the rotational speed of the turbine 4b, the turbine torque sensor 24 for outputting a signal corresponding to the torque of the turbine 4b, and the output shaft 7 of the automatic transmission 5. Output signals from a transmission output rotational speed sensor 25 that outputs a signal corresponding to the rotational speed and a transmission output torque sensor 26 that outputs a signal corresponding to the torque of the output shaft 7 of the automatic transmission 5 are input.

  Although the control performed by the ECU 20 is diverse, the following description will focus on the control related to the present invention. FIG. 2 is a flowchart showing an example of a control routine for engine output torque control performed by the ECU 20. The program for this routine is held in the ROM of the ECU 20, and is repeatedly executed at a predetermined calculation cycle. First, the ECU 20 detects an acceleration request from the driver in step S1. Specifically, the accelerator opening Acc is acquired with reference to the output signal of the accelerator opening sensor 22. Next, in step S3, referring to the output signals of the engine rotation speed sensor 21, the turbine rotation speed sensor 23, and the transmission output rotation speed sensor 25, the operation state of the internal combustion engine 2 is set to the rotation speed of the internal combustion engine 2. A certain engine rotation speed Ne, a turbine rotation speed Nt that is the rotation speed of the turbine 4b, and a transmission output rotation speed No that is the rotation speed of the output shaft 7 of the automatic transmission 5 are acquired.

  Next, in step S3, a shift stage Sft_b before switching of the automatic transmission 5 and a shift stage Sft_a after switching are detected. These shift speeds Sft_b and Sft_a can be obtained from processing information of shift control (not shown) executed by the ECU 20 in parallel with FIG. In this shift control, the shift speed Sft_a after switching is determined based on the shift diagram shown in FIG. The shift diagram in FIG. 7 associates the respective shift stages with the rotational speed No of the output shaft 7 of the automatic transmission 5 and the accelerator opening degree Acc as variables, and the solid line indicates the upshift and the broken line indicates the downshift, respectively. Show.

  Next, in step S4, the shift speed Sft_b and the shift speed Sft_a are compared to determine whether or not a downshift is performed. Needless to say, in the case of a downshift, the gear ratio after switching becomes larger than the gear ratio before switching. When the downshift is not performed, the process proceeds to step S11, and 0 (zero) is substituted for the output torque difference ΔTo that can occur before and after the downshift, and the process proceeds to step S9. When downshift is performed, the process proceeds to step S5 to estimate the shift timing. FIG. 3 is an explanatory diagram for explaining the outline of the shift timing estimation process in step S5, and FIG. 4 is a flowchart showing details of the shift timing estimation process. First, the outline of the shift timing estimation process will be described with reference to FIG.

The Figure 3 is a temporal change of the turbine rotational speed Nt and the target rotational speed NoSft from the start time t ₀ of the downshift until completion time t ₁ is shown, the time t _n is the current calculation period time t _n-1 indicates the previous calculation time, and time tn _{+ 1} indicates the next calculation time. As shown in FIG. 3, the feature of the present embodiment is that a marginal rotation speed Nmarg given as a difference between the target rotation speed NoSft and the turbine rotation speed Nt is set to a target from the previous calculation time t _n-1 to the current calculation time t _n. This is a point to be predicted in consideration of the respective temporal changes ΔNoSft and ΔNt of the rotational speed NoSft and the turbine rotational speed Nt. In other words, a margin rotational speed Nmarg in the next calculation period t _{n + 1} is calculated in the current calculation time t _n, the margin rotational speed Nmarg identifies as completing transmission timing downshift timing goes to zero or below a predetermined value . As a result, it can be determined whether or not the shift timing comes between the current calculation timing t _n and the next calculation timing t _{n + 1,} so that the shift timing can be accurately captured without losing the shift timing.

  Next, the shift timing estimation process will be specifically described with reference to FIG. First, in step S51, the target rotational speed NoSft is calculated by Equation 1.

    NoSft = No × Ratio (Sft_a) ……………………… 1

  Here, Ratio (x) is a function that gives a gear ratio according to the gear stage x, Ratio (Sft_a) means a gear ratio after the gear change, and Ratio (Sft_b) means a gear ratio before the gear shift.

  Next, a time change ΔNt of the turbine rotation speed Nt is calculated by Equation 2 in step S52.

    ΔNt = Nt−Ntold …… 2

  Here, Nold is the turbine rotation speed at the previous calculation.

  Next, the time change ΔNoSft of the target rotational speed NoSft is calculated by Equation 3 in step S53.

    ΔNoSft = NoSft−NoSftold 3

  Here, NoSftold is the target rotational speed at the time of the previous calculation.

  Next, in step S54, the current turbine rotational speed Nt is replaced with the previous turbine rotational speed Nold, and the current target rotational speed NoSft is replaced with the previous target rotational speed NoSftold. That is, Nold = Nt and NoSftold = NoSft.

  Next, a marginal rotation speed Nmarg is calculated by Equation 4 in step S55.

    Nmarg = NoSft−Nt−α (ΔNt−ΔNoSft) ……………… 4

  Here, α is a coefficient of 1 or more that is set to a larger value as the load of the internal combustion engine 2 is larger, and is provided for estimating how much the turbine rotational speed and the target rotational speed will change by the next calculation timing. .

  Next, in step S56, it is determined whether or not the marginal rotation speed Nmarg is 0 or less. If it is 0 or less, the shift timing determination flag Nmarg_jdg is set in step S57 (Nmarg_jdg = 1). Is cleared (Nmarg_jdg = 0). Then, the process proceeds to step S6 in FIG.

  In step S6 of FIG. 2, the output torque difference ΔTo at the shift timing is estimated. FIG. 5 is a flowchart showing details of the output torque difference estimation process executed in step S6. As shown in FIG. 5, first, in step S61, the turbine torque Tt is detected by referring to the signal from the turbine torque sensor 24, and in the subsequent step S62, the signal of the transmission output torque sensor 26 is referenced to determine the transmission. The output torque To is detected.

  Next, in step S63, a pre-shift output torque To_b that is an output torque of the output shaft 7 of the automatic transmission 5 before the shift is calculated. Here, the transmission output torque To detected in step S62 is defined as the pre-shift output torque To_b. Next, in step S64, a post-shift output torque To_a that is an output torque of the output shaft 7 of the automatic transmission 5 after the shift is calculated by Formula 5.

    To_a = Tt × Ratio (Sft_a) 5

  Next, in step S65, the output torque difference ΔTo is calculated using equation 6, and the process proceeds to step S7 in FIG.

    ΔTo = To_a−To_b ……………………… 6

  In step S7 of FIG. 2, it is determined whether or not the shift timing determination flag Nmarg_jdg is set. If it is set, the process proceeds to step S8. Otherwise, the process proceeds to step S11, and the output torque difference ΔTo is set. Zero.

  In step S8, the resonance frequency fv in the drive system of the internal combustion engine 2 is read. The resonance frequency fv is preset for each gear position, that is, for each gear ratio, and the corresponding relationship is stored in the ROM of the ECU 20. Thereby, ECU20 functions as a resonance frequency memory | storage means. After reading the resonance frequency fv corresponding to the gear position after the downshift in step S8, the process proceeds to step S9 to calculate the engine required torque Te_dem.

  FIG. 6 is a flowchart showing details of the engine required torque calculation process executed in step S9 of FIG. First, in step S91, referring to the output signal of the transmission output torque sensor 26, the transmission output torque To is detected. Next, in step S92, a transmission required torque addition value To_fill is calculated. This torque addition value To_fill is obtained by removing the component corresponding to the resonance frequency fv from the output torque difference ΔTo, and corresponds to the change amount of the transmission required torque according to the present invention. This torque addition value To_fill can be obtained by using, for example, a band elimination filter that blocks passage of a component corresponding to the resonance frequency fv and allows passage of other components.

  Next, in step S93, the transmission required torque To_dem is calculated by Equation 7.

    To_dem = To + To_fill ……………………… 7

  Next, in step S94, the torque ratio t of the torque converter 4 is calculated. The calculation of the torque ratio t can be realized, for example, by preparing in advance a map that gives the torque ratio t using the ratio Nt / Ne between the turbine speed Nt and the engine speed Ne as a variable, and referring to the map.

  Next, in step S95, the gear ratio required torque To_dem is converted into the engine required torque Te_dem. Here, a map for giving the engine required torque Te_dem is prepared using the transmission required torque To_dem, the shift stage Sft_a after the shift and the torque ratio t as variables, and this conversion is realized by referring to the map. Then, the process proceeds to step S10 in FIG.

  In step S10 of FIG. 2, the fuel injection amount of the internal combustion engine 2 is controlled so that the engine required torque Te_dem calculated in step S9 is output from the crankshaft 3, and this routine is finished.

  By executing the above control routine, the engine required torque Te_dem that can suppress resonance with the drive system of the internal combustion engine 2 is output from the internal combustion engine 2 on the condition that the shift timing has been reached, and the engine required torque Te_dem Is calculated based on the output torque difference ΔTo that can occur before and after the downshift. As a result, it is possible to reduce the shock that occurs during the downshift, and it is possible to prevent the output torque of the internal combustion engine 2 from excessively decreasing in order to reduce the shock. Accordingly, it is possible to sharpen the torque rise from the start to the end of the downshift while reducing the shock that occurs during the downshift.

(Second form)
Next, a second embodiment of the present invention will be described with reference to FIG. This form is the same as the first form except for the content of the engine required torque calculation process executed in step S9 of FIG. Therefore, the description of the same part as the first embodiment is omitted below. FIG. 8 shows the contents of the engine required torque calculation processing according to the second embodiment. The same processes as those in the engine required torque calculation process shown in FIG. After calculating the torque ratio t in step S94, the process proceeds to step S951, and the turbine required torque Tt_dem is calculated using Equation 8.

    Tt_dem = To_dem × Ratio (Sft_a) + It × ΔNt ...... 8

  Here, It is the inertia torque of the turbine 4b.

  Next, proceeding to step S952, the turbine required torque Tt_dem is converted into the engine required torque Te_dem. Here, a map that provides the engine required torque Te_dem with the turbine required torque Tt_dem and the torque ratio t as variables is prepared, and this conversion is realized by referring to the map.

  According to the second mode, since the turbine required torque Tt_dem is calculated in accordance with the gear ratio after the downshift, it is necessary to consider the gear position in order to calculate the engine required torque Te_dem as in the first mode. There is no. Accordingly, there is an advantage that the map variable is reduced by one as compared with the first form, and the map information amount can be reduced.

(Third form)
Next, a third embodiment of the present invention will be described with reference to FIG. This form is the same as the first form except for the content of the engine required torque calculation process executed in step S9 of FIG. Therefore, the description of the same part as the first embodiment is omitted below. FIG. 9 shows the contents of the engine required torque calculation processing according to the third embodiment. The same process as the engine required torque calculation process shown in FIG. After calculating the turbine required torque Tt_dem in step S951, the process proceeds to step S953, and the engine speed change ΔNe is calculated. This time change means a change in the engine speed Ne from the previous calculation time to the current calculation time. Next, the process proceeds to step S954, and the pump request torque Tp_dem of the pump 4a of the torque converter 4 is calculated based on Equation 9.

    Tp_dem = Tt_dem / t ……………………… 9

  Next, the pump request torque Tp_dem is converted into the engine request torque Te_dem based on Expression 10.

    Te_dem = Tp_dem + Ip × ΔNe ………………………… 10

  Here, Ip is the inertia torque of the pump 4a.

  According to the third embodiment, since no map is required to calculate the engine required torque Te_dem, there is an advantage that labor for creating the map can be reduced. Further, since the inertia of the torque converter 4 is taken into account in the process of calculating the engine required torque Te_dem, the calculation accuracy of the engine required torque Te_dem is improved.

(4th form)
Next, a fourth embodiment of the present invention will be described with reference to FIG. This mode is characterized by the method of estimating the output torque difference, and can be applied to each mode described above. Hereinafter, description of common parts with the above-described embodiments will be omitted. In each of the embodiments described above, the turbine torque Tt and the transmission output torque To are detected by the torque sensors 24 and 26 in steps S61 and S62 in FIG. 5 in order to estimate the output torque difference. Then, the output torque difference is estimated without providing these torque sensors. FIG. 10 is a flowchart showing details of output torque difference estimation processing according to the fourth embodiment. First, in step S261, the ECU 20 calculates the engine output torque Te, which is the output torque of the crankshaft 3, based on the accelerator opening Acc and the engine rotational speed Ne. Calculation of the engine output torque Te can be realized by preparing a map for giving the engine output torque Te using the engine speed Ne and the accelerator opening Acc as variables as shown in FIG. 11 and referring to the map.

  Next, in step S262, the pre-shift output torque To_b is calculated using Equation 11.

    To_b = Te × Ratio (Sft_b) 11

  Next, in step S263, the post-shift output torque To_a is calculated using Equation 12.

    To_a = Te × Ratio (Sft_a) ……………………… 12

  Next, in step S264, the output torque difference ΔTo is calculated by the above-described equation 6, and the process proceeds to step S7 in FIG.

  The pre-shift output torque To_b and the post-shift output torque To_a can also be calculated by other methods described below.

(Calculation of pre-shift output torque To_b)
(1-1) Assuming that the torque is not completely transmitted by the automatic transmission 5 immediately before the completion of the shift, the pre-shift output torque To_b may be calculated as 0 (zero) based on the assumption.

(1-2) It is assumed that the torque is not completely transmitted by the automatic transmission 5 immediately before the completion of the shift and is in a driven state by the drive wheels 10, and based on the assumption, the output torque To_b before the shift is obtained by Expression 13. May be calculated.

    To_b = (R / L) × r / R_dif × b ……………………… 13

  Here, R / L is a running resistance, and is calculated by a map or function using the running speed V of the vehicle 1 as a variable. The traveling speed V of the vehicle 1 is detected based on an output signal from a vehicle speed sensor (not shown). Also, r is the rotation radius of the drive wheel 10, R_dif is the gear ratio of the differential device 8, b is the efficiency of the differential device 8, and these are held in the ECU 20 in advance.

(1-3) The pre-shift output torque To_b can also be calculated by the formula (14) taking into account the longitudinal acceleration G of the vehicle in the method (1-2).

    To_b = (G × M + R / L) × r / R_dif × b ……………………… 14

  Here, M is the weight of the vehicle 1. The acceleration G can be detected by providing an acceleration sensor in the vehicle 1 and can be detected from the acceleration sensor, or can be calculated by time differentiation of the vehicle speed.

(1-4) Before the shift is completed, most of the turbine torque is used for increasing the rotation. Therefore, Formula 15 is established between the turbine torque Tt and the pump torque Tp in consideration of the inertia of the turbine.

    Tt = Tp × t−It × ΔNt 15

  Here, the pump torque Tp can be obtained by Expression 16.

Tp = C × Ne ² ……………………… 16

  C in Expression 16 is a capacity coefficient of the torque converter. Based on the turbine torque Tt obtained by Expression 15, the output torque To_b before shifting can be calculated by Expression 17.

    To_b = Tt × Ratio (Sft_b) ……………………… 17

(Calculation of post-shift output torque To_a)
(2-1) First, the engine output torque Te is calculated by the above-described method, and the pump torque Tp is calculated by Expression 18 using the engine output torque Te and the temporal change ΔNe of the engine speed.

    Tp = Te−Ip × ΔNe …………………… 18

  The pump torque Tp obtained by Expression 18 is substituted into Expression 15 to obtain the turbine torque Tt, and the turbine torque Tt is substituted into Expression 19 to calculate the post-shift output torque To_a. Note that, when obtaining the turbine torque Tt in Expression 15, it may be considered that ΔNt = 0 in consideration of the fact that ΔNt becomes smaller immediately after the shift.

    To_a = Tt × Ratio (Sft_a) ……………………… 19

(2-2) Further, the post-shift output torque To_a can be calculated in the same manner as (1-4) above. That is, the pump torque Tp is obtained by Expression 16, the pump torque Tp is substituted into Expression 15, the turbine torque Tt is calculated, and the post-shift output torque To_a can be calculated by Expression 19. Note that, when obtaining the turbine torque Tt in Expression 15, it may be considered that ΔNt = 0 in consideration of the fact that ΔNt becomes smaller immediately after the shift.

  In Step S262 and Step S263 of FIG. 10, the above method is appropriately selected and the output torque To_b before the shift and the output torque To_a after the shift are calculated, respectively, so that the output torque difference ΔTo without using the torque sensors 24 and 26 is calculated. Can be estimated in various ways.

  In each of the above embodiments, by executing the process of step S5 (FIG. 4) of FIG. 2, the ECU 20 executes the process of step S6 (FIG. 5 or 10) of FIG. 2 as the shift timing estimating means according to the present invention. As a result, the ECU 20 executes the processing of step S9 (FIG. 6, FIG. 8, or FIG. 9) of FIG. 2 as the output torque difference estimating means according to the present invention, whereby the ECU 20 serves as the engine required torque calculating means according to the present invention. The ECU 20 functions as engine control means by executing the processing of step S10 in FIG.

  Further, by executing the processing of step S51 to step S55 in FIG. 4, the ECU 20 functions as a surplus rotation speed predicting unit, and by executing the processing of step S56 to step S58 in FIG. Function.

  Further, by executing the processing of steps S91 to S93 of FIGS. 6, 8, and 9, the ECU 20 can perform step S95 of FIG. 6, step S952 of FIG. The ECU 20 functions as the conversion means according to the present invention by executing the process of step S955 of FIG.

  However, the present invention is not limited to the above embodiments, and can be implemented in various forms within the scope of the gist of the present invention. In each of the above embodiments, the control device according to the present invention is applied to an internal combustion engine in which an automatic transmission is connected to a crankshaft via a torque converter. However, the control device according to the present invention includes an electromagnetic clutch instead of a torque converter. The present invention can also be applied to the provided internal combustion engine.

The figure which showed the outline of the vehicle carrying the internal combustion engine to which the control apparatus which concerns on this invention was applied. The flowchart which showed an example of the control routine of engine output torque control. Explanatory drawing explaining the outline | summary of a shift timing estimation process. 5 is a flowchart showing details of a shift timing estimation process. The flowchart which showed the detail of the output torque difference estimation process. The flowchart which showed the detail of the engine request torque calculation process. The figure which showed an example of the shift map. The flowchart which showed the detail of the engine required torque calculation process which concerns on a 2nd form. The flowchart which showed the detail of the engine required torque calculation process which concerns on a 3rd form. The flowchart which shows the detail of the output torque difference estimation process which concerns on a 4th form. The figure which showed an example of the map for calculating an engine output torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Internal combustion engine 3 Automatic transmission 4 Torque converter 4a Pump 4b Turbine 20 ECU (shift timing estimation means, output torque difference estimation means, engine demand torque calculation means, engine control means, margin rotation speed prediction means, shift timing specification means , Resonance frequency storage means, transmission required torque calculation means, conversion means)

Claims (7)

Applied to an internal combustion engine provided with an automatic transmission that is connected to an output shaft of the internal combustion engine and can be switched to a plurality of gear ratios having different sizes.
A shift timing estimating means for estimating a shift timing at which the downshift is completed when a downshift for switching from a small gear ratio to a large gear ratio is performed in the automatic transmission, and may occur before and after the downshift. Based on the output torque difference, the engine required torque of the internal combustion engine capable of suppressing resonance between the output torque difference estimating means for estimating the output torque difference of the automatic transmission and the drive system of the internal combustion engine at the shift timing. The engine required torque is calculated so that the engine required torque calculated by the engine required torque calculating means is output from the output shaft of the internal combustion engine on the condition that the shift timing has been reached. An internal combustion engine control device comprising: an engine control means for controlling. The automatic transmission is connected to the output shaft of the internal combustion engine via a torque converter including a pump connected to the output shaft of the internal combustion engine and a turbine combined with the pump.
In the process from the start to the completion of the downshift, the shift timing estimation means is configured to obtain a target rotational speed obtained by multiplying the output rotational speed of the automatic transmission by the speed ratio after the downshift and a turbine rotational speed of the turbine. The margin rotation speed prediction means for predicting the margin rotation speed given as the difference in consideration of the respective temporal changes of the target rotation speed and the turbine rotation speed, and the margin rotation speed predicted by the margin rotation speed prediction means The control apparatus for an internal combustion engine according to claim 1, further comprising: a shift timing specifying unit that specifies a timing when the shift is equal to or less than a predetermined value as the shift timing. Resonance frequency storage means for storing the resonance frequency of the drive system for each gear ratio;
The engine required torque calculating means calculates the engine required torque based on the stored contents of the resonance frequency storage means so that a component corresponding to the resonance frequency in the gear ratio after the downshift is removed. The control apparatus for an internal combustion engine according to claim 1 or 2. The engine required torque calculating means includes a transmission required torque calculating means for calculating a transmission required torque of the automatic transmission corresponding to the output torque difference, and the transmission required torque calculated by the transmission required torque calculating means. Conversion means for converting the engine required torque into
The transmission required torque calculating means calculates the transmission required torque based on the stored contents of the resonance frequency storage means so that a component corresponding to the resonance frequency in the gear ratio after the downshift is removed. The control device for an internal combustion engine according to claim 3.   The transmission required torque calculation means calculates a change amount of the transmission required torque by removing a component corresponding to the resonance frequency in the transmission ratio after the downshift from the output torque difference, and the change amount is calculated as the change amount. The control apparatus for an internal combustion engine according to claim 4, wherein the transmission request torque is calculated by adding to a current output torque of the transmission. The margin rotation speed prediction means is configured to sequentially predict the margin rotation speed at a calculation timing of a predetermined cycle, and the target rotation speed at the current calculation timing is NoSft, and the turbine at the current calculation timing. , The time change from the previous calculation timing of the target rotation speed to the current calculation timing is ΔNoSft, the time change from the previous calculation timing of the turbine rotation speed to the current calculation timing is ΔNt, When a coefficient of 1 or more that is set to a larger value as the load of the internal combustion engine is larger is α and the marginal rotation speed is Nmarg, the following equation is obtained: Nmarg = NoSft−Nt−α (ΔNt−ΔNoSft)
The control apparatus for an internal combustion engine according to any one of claims 1 to 4, wherein the marginal rotation speed is predicted at step (5).   The output torque difference estimating means estimates the output torque difference by multiplying the engine output torque output from the output shaft of the internal combustion engine by the difference in the gear ratio before and after the downshift. The control device for an internal combustion engine according to any one of claims 1 to 6.

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