JP2004137907A - Control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid excess torque increase and reduce speed change shock upon downshifting, in regard to an engine equipped with an automatic transmission. <P>SOLUTION: A rotation synchronous torque calculating part 201 calculates a rotation synchronous torque TQTMSTAC for achieving engine speed after downshifting. A target engine torque calculating part 202 calculates a required engine torque TTEIF according to an accelerator opening (211), a torque increase amount maximum value dTSFTi set for each gear (212), and, by adding up these figures, a rotation synchronous limit torque TRQMDLT (213). The rotation synchronous torque TQTMSTAC and the rotation synchronous limit torque TRQMDLT are compared, and the smaller one is outputted as the target engine torque (rotation synchronous control target torque) TRQNUT (213). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an engine control device that reduces a shift shock by increasing an engine torque during a downshift of an automatic transmission.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a technique for reducing a shift shock by increasing an engine output torque at the time of a downshift of an automatic transmission (for example, see Patent Document 1).
Such a torque-up control at the time of a downshift is performed in the inertia phase from the time when the clutch of the current gear (for example, the third speed) starts to be disengaged until the connection of the clutch of the next gear (for example, the second speed) is started. , The shift shock is prevented by increasing the engine output torque.
[0003]
[Patent Document 1]
JP-A-9-105458
[Problems to be solved by the invention]
By the way, conventionally, such an increase in the engine output torque is calculated by calculating an engine output torque (hereinafter, referred to as a rotation synchronization torque) that achieves the engine rotation speed after the downshift, and controlling the engine so that the rotation synchronization torque is obtained. However, for example, in the case of an automatic transmission having a manual shift mode capable of manual shifting, a downshift is performed by the driver's operation, so that a larger rotation synchronization torque than expected is provided. There is a possibility that a sudden increase in rotation will occur due to the calculation.
[0005]
Also, regardless of whether the shift mode is the manual shift mode or the automatic shift mode, if an erroneous rotation synchronizing torque is calculated, an unexpected torque is input to the automatic transmission during shifting, and the clutch is shifted. There is also a problem that abnormal abrasion or the like occurs. The present invention has been made in view of such a problem, and an object of the present invention is to reliably prevent an excessive increase in engine output torque in an engine control device that controls an increase in engine output torque during a downshift. .
[0006]
[Means for Solving the Problems]
For this reason, the engine control device according to the present invention is an engine control device that controls the engine output torque to increase when the automatic transmission is downshifted. Thus, the torque increase limit value is set.
[0007]
【The invention's effect】
According to the engine control device of the present invention, the torque increase amount for effectively reducing the shift shock due to the downshift is calculated, but the viewpoint other than the reduction of the shift shock, for example, safety and performance A torque increase limit value is set for securing (maintaining). This reduces shift shock during downshifts as much as possible, prevents excessive increase in engine output torque, and ensures that unexpected torque is input to the automatic transmission and that rapid rotation increases. Can be avoided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of an engine according to an embodiment of the present invention. In FIG. 1, a throttle valve 4 driven by a throttle motor 3 is provided in an intake passage 2 of an engine 1.
[0009]
An automatic transmission 5 is connected to an output side of the engine 1. The automatic transmission 5 has, in addition to the automatic transmission mode, a manual transmission mode in which a manual transmission can be performed according to a driver's request. The automatic transmission 5 includes a torque converter 6 connected to an output shaft of the engine 1, The transmission mechanism 6 includes a transmission mechanism (gear mechanism) 7 connected to the output side of the transmission 6 and a hydraulic control mechanism 8 for connecting / disconnecting various transmission elements (clutches and the like) in the transmission mechanism 7.
[0010]
The operating oil pressure for the oil pressure control mechanism 8 is controlled via various electromagnetic valves. Here, only the shift solenoids 9 and 10 for automatic shifting and the lock-up solenoid 11 for lock-up are shown. The shift solenoids 9 and 10 and the lock-up solenoid 11 are connected to an electronic control unit (hereinafter, referred to as ECU) 12.
[0011]
The ECU 12 includes a throttle sensor 21 for detecting the opening of the throttle valve 4, an accelerator opening sensor 22 for detecting the depression amount APS of the accelerator pedal, a water temperature sensor 23 for detecting the engine cooling water temperature Tw, and detecting an engine rotation speed Ne. Rotation speed sensor 24, a gear position sensor 25 for detecting the gear position GP of (the gear mechanism of) the automatic transmission 5, and a driver operating the transmission mode (automatic transmission mode, manual transmission mode) of the automatic transmission 5 Signals are input from a mode switch 26, a shift position sensor 27 for detecting a shift lever position SP, a vehicle speed sensor 28 for detecting a vehicle speed VSP, and the like.
[0012]
Then, in the automatic shift mode, the ECU 12 sets an optimal shift speed by referring to a preset map based on the accelerator operation amount APS and the vehicle speed VSP, and sets the optimal shift speed to the set shift speed. The shift solenoids 114 and 15 are controlled. On the other hand, in the manual shift mode, the driver sets an upshift side or a downshift side one step from the current shift step, respectively, according to an upshift operation or a downshift operation performed via the shift lever. The shift solenoids 14 and 15 are controlled so as to achieve this gear stage.
[0013]
The ECU 12 executes engine control such as fuel injection control and ignition timing control based on signals from the various sensors, calculates a target engine torque, and controls the throttle so that the target engine torque is obtained. The motor 5 is driven to control the opening of the throttle valve 4 to perform engine output torque control.
Here, the engine output torque control (calculation of the target engine torque) performed by the ECU 12 during the downshift will be described.
[0014]
FIG. 2 is a block diagram showing a portion of the ECU 12 related to engine output torque control. As shown in FIG. 2, the ECU 12 is configured to include a rotation synchronization torque calculation unit 201 and a target engine torque calculation unit 202.
When detecting a downshift operation by the driver in the manual shift mode (that is, when a downshift request is made), the rotation synchronous torque calculation unit 201 estimates the engine speed after the downshift, and estimates the estimated engine speed. The engine output torque (rotation synchronization torque) vTQTMSTAC for achieving the rotation speed is calculated. The rotation synchronization torque vTQTMSTAC calculated here is calculated so as to effectively reduce the shift shock caused by the downshift, and is output to the target engine torque calculation unit 202 (first comparison unit 215 described later).
[0015]
The target engine torque calculation unit 202 calculates a target engine torque TRQNTU at the time of the downshift (hereinafter referred to as a rotation synchronization control target torque) as follows.
First, the driver required engine torque calculating unit 211 calculates an engine output torque (required engine torque) TTEIF requested by the driver based on the accelerator operation amount (accelerator opening) APS, and adds the required engine torque TTEIF to be described later. The output is output to the section 213 and the second comparison section 217.
[0016]
When a downshift request is made, the torque limiter setting unit 212 sets a torque increase upper limit value dTSFTi # for limiting the torque increase with respect to the requested engine torque TTEIF (for a 4-speed AT: i = 1 to 4 ) Is set. The torque increase amount upper limit dTSTFi set here is set, for example, to prevent a sudden increase in engine output torque (input torque to the automatic transmission 5) in order to ensure (maintain) safety and performance. This is set for each actual gear position CURGP (gear position) (see FIG. 4).
[0017]
The adder 213 adds the torque increase upper limit dTSTFi to the required engine torque TTEIF to obtain an upper limit of the engine output torque during downshift (hereinafter referred to as a rotation synchronization limit torque) TRQMDLT (= TTEIF + dTSTFi #). It calculates and outputs this to the first switching output unit 214.
In the first switching output unit 214, there is a downshift request (downshift determination), manual shift mode (M mode determination), no fuel cut (non-fuel cut determination), and vehicle speed VSP at a predetermined speed ( For example, the rotation synchronization control limit torque TRQMDLT is set on condition that the speed is 10 km / h or more (vehicle speed determination). On the other hand, if any of the above conditions is not satisfied, a fictitious value (for example, a negative max torque) is set, and finally, the required engine torque TTEIF is set to the target engine torque (rotation synchronization) at the time of the downshift. (Control target torque) (refer to a second comparison unit 217 described later). Then, the torque set here is output to first comparing section 215.
[0018]
It should be noted that the above-described fuel cut determination is performed by performing the contradictory control of increasing the engine output torque by selecting the rotation synchronization limit torque TRQMDLT during the fuel cut in which the engine output torque (engine rotation speed) decreases. Therefore, the stability of the control is ensured by avoiding this, and the vehicle speed judgment is performed in the low vehicle speed region because the shift shock due to the downshift is small. By excluding, the control load is effectively reduced and the calculation load is reduced.
[0019]
The first comparing section 215 compares the torque output from the first switching output section 214 with the rotation synchronization torque TQTMSTAC, sets the smaller one, and outputs the smaller one to the second switching output section 216. As a result, when there is a downshift request that satisfies the above conditions, the rotation synchronization torque TQTMSTAC calculated to reduce the shift shock is selected as an upper limit value for ensuring safety and performance. This is limited only to the case where it is smaller than the set rotation synchronization limit torque TRQMDLT.
[0020]
The second switching output section 216 outputs the signal from the first comparing section 215 on condition that there is no communication error or the like with the rotation synchronous torque calculating section 201 (and the target engine torque calculating section 202) (communication error determination). Set the torque. On the other hand, if there is a communication error or the like, a fictitious value (for example, a negative max torque) is set as in the case of the first switching output unit 214, and finally, the required engine torque TTEIF becomes rotationally synchronized. The control target torque is set (refer to a second comparison unit 217 described later). The torque set here is output to the second comparing section 217.
[0021]
The second comparing section 217 compares the torque output from the second switching output section 216 with the required engine torque TTEIF and selects the larger one to be the rotation synchronization control target torque TRQNTU (accordingly, usually, The torque output from the second switching output unit 216 will be selected).
Then, the ECU 12 controls the opening of the throttle valve 4 by driving the throttle motor 5 so as to obtain the target engine torque TRQNTU, thereby reliably avoiding excessive torque increase and reducing the engine output torque. Execute torque up control to suppress shift shock during downshift.
[0022]
FIG. 3 is a flowchart showing the torque up control at the time of downshift in the manual shift mode described above. In FIG. 3, in step 1, it is determined whether or not the shift mode of the automatic transmission 5 is the manual shift mode. This determination is made based on an input signal from the mode switch 26. If the mode is the manual shift mode (when the M mode is selected), the process proceeds to step 2, and if the mode is not the manual shift mode (the case of the automatic shift mode), the process proceeds to step 9.
[0023]
In step 2, it is determined whether there is a downshift request. This determination is made based on an input signal from the shift position sensor 27. If there is a downshift request, go to step 3.
In step 3, it is determined whether the vehicle speed is equal to or higher than a predetermined speed (for example, 10 km / h). If the speed is equal to or higher than the predetermined speed, the process proceeds to step 4.
[0024]
In step 4, it is determined whether the fuel is being cut. If the fuel is not being cut, the process proceeds to step S5.
In step 5, it is determined whether there is a communication error. For example, when the rotation synchronization torque TQTMSTAC is not input from the rotation synchronization torque calculation unit 201 (the target engine torque calculation unit 202 cannot be received) or when it is input but has an abnormal value, there is a communication error. Is determined. If there is no communication error, go to step 6.
[0025]
In step 6, a rotation synchronization torque TQTMSTAC for suppressing a shift shock during a downshift is calculated.
In step 7, a torque increase upper limit dTSFTi corresponding to the gear position is added to the driver request torque TTEIF to calculate a rotation synchronization limit torque TRQMDLT (= TTEIF + dTSFTi #) for ensuring safety and performance.
[0026]
In step 8, the smaller of the rotation synchronization torque TQTMSTAC and the rotation synchronization limit torque TRQMDLT is selected, and the smaller one is compared with the selected torque and the driver request torque TTEIF. Set as torque TRQNTU.
On the other hand, if it is determined in steps 1 to 5 that the vehicle is not in the manual shift mode, that there is no downshift request, that the vehicle speed is lower than the predetermined speed, that the fuel is being cut, and that there is a communication error, the process proceeds to step 9. Then, a negative torque max value is set as the rotation synchronization limit torque. In this case, the driver request engine torque vTTEIF is set as the target engine torque (steps 9 → 8).
[0027]
FIG. 4 is a flowchart for setting the torque increase upper limit dTSFTi # (i = 1 to 4) (in the case of a 4-speed AT).
In FIG. 4, in step 11, it is determined whether there is a downshift request. If there is a downshift request, the process proceeds to step 12, and if there is no downshift request, the process ends.
[0028]
In steps 12 to 14, it is determined whether the current actual gear position CURGP (gear position) is any of first to fourth speeds. If the actual gear position CURGP is the first speed, the process proceeds to step 15, where the first speed torque increase upper limit value dTSFT1 # (for example, 35N) is set and the process ends. If the actual gear position CURGP is the second speed, the routine proceeds to step 16, sets the torque increase upper limit dTSFT2 # (for example, 55N) for the second speed, and ends. If the actual gear position CURGP is the third speed, the process proceeds to a step 17, sets the torque increase upper limit value dTSFT3 # (for example, 85N) for the third speed, and ends the processing. If the actual gear position CURGP is the fourth speed, the process proceeds to step 18, where the torque increase upper limit value dTSFT4 # (for example, 126N) for the fourth speed is set and the process ends.
[0029]
FIG. 5 is a time chart of the torque up control when downshifting from third gear to second gear.
As shown in FIG. 5, when there is a downshift request, rotation synchronization limit torque TRQMDLT (= TTEIF + dTSFT2) and rotation synchronization torque TQTMSTAC are calculated. Here, since the rotation synchronization torque TQTMSTAC> the rotation synchronization limit torque TRQMDLT, the rotation synchronization limit torque TRQMDLT is selected to become the rotation synchronization control target engine torque TRQNTU. Then, the rotation synchronous control target torque TRQNTU is output during a predetermined gearshift state (for example, from when the third speed clutch starts to be disengaged until when the second speed clutch starts to be engaged) (FIG. 5B). ).
[0030]
As a result, the throttle opening is controlled to increase (torque up) so that the rotation synchronous control target torque TRQNTU is obtained (FIG. 5C), and the engine speed increases (FIG. 5D). .
The embodiment described above has the following effects.
(1) Since the torque increase amount upper limit value (limit value) dTSFTi is set for each shift speed, an appropriate limit value can be set according to the shift speed, so that an excessive increase in engine output torque is prevented. At the same time, it is possible to reduce the shift shock at each shift speed to the maximum.
(2) Since the engine output torque is increased by controlling the opening of the throttle valve 4, the engine output torque can be easily changed by the ECU 12.
[0031]
In the above embodiment, only the case of the manual shift mode is described. However, the present invention is not limited to this, and may be applied at the time of a downshift in the automatic shift mode. In addition to controlling the opening of the throttle valve 4, the engine output torque may be increased by controlling the ignition timing.
[Brief description of the drawings]
FIG. 1 is a system diagram of an engine according to an embodiment of the present invention.
FIG. 2 is a block diagram showing torque up control (rotation synchronization control) at the time of a downshift.
FIG. 3 is a flowchart showing torque up control (rotation synchronization control) at the time of a downshift.
FIG. 4 is a flowchart for setting a torque increase upper limit value.
FIG. 5 is a time chart showing torque up control at the time of downshifting from third speed to second speed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 3 ... Throttle motor, 4 ... Throttle valve, 5 ... Automatic transmission, 12 ... Electronic control unit (ECU), 21 ... Throttle sensor, 22 ... Accelerator opening sensor, 25 ... Gear position sensor, 26 ... Mode Switch, 27
... Shift position sensor, 28 ... Vehicle speed sensor

Claims (4)

In an engine control device for increasing the engine output torque during a downshift of an automatic transmission,
An engine control device, wherein a torque increase limit value is set for a required torque increase calculated in accordance with an increase in an engine rotation speed. 2. The engine control device according to claim 1, wherein the torque increase amount limit value is set for each shift speed. 3. The engine control device according to claim 1, wherein the control for increasing the engine output torque is performed by increasing a throttle opening. An engine control device having an automatic transmission,
Driver request torque calculation means for calculating a driver request torque based on the accelerator opening,
When a downshift request is made, a rotation synchronization torque calculation unit that calculates a rotation synchronization torque that achieves the engine rotation speed after the downshift,
Torque increase amount limit value setting means for setting a torque increase amount limit value for the driver request torque;
Target engine torque setting means for comparing the rotation synchronization torque and the rotation synchronization limit torque obtained by adding the torque increase amount limit value to the driver request torque and setting a smaller one as the target engine torque;
Output torque control means for increasing and controlling the engine output torque so that the target engine torque is obtained;
A control device for an engine, comprising:

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