KR20080003743A - Device and method for preventing over-rotation of internal combustion engine - Google Patents

Abstract

A device and a method for preventing over-rotation of an internal combustion engine are provided to reduce flare by relieving rise of coupling pressure of frictional elements of a coupling side from being delayed with respect to the increasing velocity of an engine torque. A device for preventing over-rotation of an internal combustion engine, includes an engine torque control unit, an RPM sensor, an over-rotation prevention unit, an over-rotation prevention release unit, and an engine torque increase velocity regulating unit. The engine torque control unit controls torque of an engine(1) based on a driver request torque. The RPM sensor detects RPM of the engine. The over-rotation prevention unit suppresses the torque controlled by the engine torque control unit based on the detected RPM of the engine, and prevents over-rotation of the engine. The over-rotation prevention unit releases the suppression of the torque performed by the over-rotation prevention unit when the RPM of the engine is lowered than a predetermined value. The engine torque increase velocity regulating unit regulates increase velocity of the torque when the suppression of the torque is released and the torque is increased during gear-shift performed by an automatic transmission(2).

Description

Engine over-rotation device and engine over-rotation method {DEVICE AND METHOD FOR PREVENTING OVER-ROTATION OF INTERNAL COMBUSTION ENGINE}

The present invention relates to an over-rotation preventing device for preventing over-rotation of the engine.

If the engine rotates beyond the upper limit of the allowable speed, it causes problems such as deterioration of the durability of the engine. Therefore, as a technique for preventing the problem, a technique as described in, for example, Japanese Patent Laid-Open No. 2004-245191 It is proposed.

This technique adversely affects the catalyst of the engine exhaust system or entails deterioration in operating efficiency when the engine is over-rotated by the on / off control of the fuel supply. By reducing the opening of the throttle valve is to prevent the engine over-rotation.

According to the technique which prevents over-rotation of an engine by reducing the opening degree of the throttle valve of patent document 1, when it shifts up in an automatic transmission during the control which prevents this over-rotation, the problem demonstrated below arises. .

When the driver is driving by pushing the accelerator pedal, the target engine torque tTe is set so that the torque of the engine is equal to the AP0 (driver's request) torque corresponding to this depression amount (acceleration opening degree AP0). When the engine speed Ne rises and control to prevent over rotation of the engine is started, the target engine torque tTe is suppressed. That is, the target engine torque tTe is set lower than the APO corresponding (driver's request) torque.

If the automatic transmission receives an upshift command from the shift stage GP = nth to GP = n + 1x during the control to prevent the engine from over-rotating, the release side to be released from the engaged state at this shift is The tightening pressure Po of the friction element (clutch or brake) is lowered. At the same time, the fastening pressure Pc of the friction element (clutch or brake) on the fastening side to be fastened from the released state at the time of this shift is raised, and the shift corresponding to the upshift command is executed.

By the progress of such an upshift, the engine speed Ne falls, and the control which prevents over rotation of an engine is canceled by this. For this reason, the target engine torque tTe suppressed by the said control returns to APO response (operator request) torque, and the opening degree of the throttle valve returns to the opening degree corresponding to the accelerator opening degree AP0 so as to realize this.

By the way, the return of the target engine torque tTe suppressed in order to prevent over-rotation is steep, and the raise of the clamping pressure Pc of the friction element of the fastening side which is responsible for an upshift raises the target engine torque tTe. There is a significant delay for the return.

For this reason, the frictional element on the fastening side to which the fastening advances by the raise of the fastening pressure Pc excessively generate | occur | produces a slip, and a so-called flare is generated. Since this flare requires a long time until the flare is settled, the shift time from the shift ratio until the effective shift ratio represented by the rotation ratio between the input shaft and the output shaft reaches the shift ratio after shifting becomes long, which causes a response delay in shifting.

An object of the present invention is to propose an engine over-rotation prevention apparatus capable of suppressing a response delay of a shift.

For this purpose, the engine over-rotation preventing device for preventing over-rotation of the engine of the present invention,

An engine torque control unit for controlling torque of the engine based on a driving force request of a driver;

A rotation speed sensor detecting a rotation speed of the engine;

An over-rotation preventing unit for suppressing over-rotation of the engine by suppressing the torque controlled by the engine torque control unit based on the detected rotational speed of the engine;

An over-rotation prevention releasing portion for releasing the suppression of torque by the over-rotation preventing portion based on the rotation speed of the engine lowered by the shift-up of the automatic transmission;

And an engine torque increase speed regulating portion for regulating the increase speed of the torque when the torque is increased by releasing the suppression of the torque by the over-rotation prevention releasing portion.

According to the engine over-rotation prevention device of the present invention, the engine rotation speed is reduced by the shift-up of the automatic transmission during the control to prevent over-rotation of the engine, the torque of the engine when the control to prevent over-rotation is released Suppress the speed of increase. For this reason, it can be alleviated that the increase speed of the torque of an engine steeps against the raise of the fastening pressure of the fastening side friction element which is responsible for an upshift. That is, it is possible to alleviate the delay of the increase in the fastening pressure of the friction element on the fastening side with respect to the increase speed of the engine torque and to reduce the flare.

For this reason, it becomes possible to avoid lengthening the shift time (the time until the effective transmission ratio represented by the rotation ratio of the input shaft and the output shaft reaches the transmission ratio after the shift), and it is possible to prevent the response delay of the shift.

An object of the present invention is to propose an engine over-rotation prevention apparatus capable of suppressing a response delay of a shift.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on the Example shown to drawing.

Fig. 1 shows a power train of a vehicle provided with an over-rotation preventing device of an engine according to an embodiment of the present invention, and a control system thereof. The power train is composed of an engine 1 and an automatic transmission 2.

The engine 1 is a gasoline engine. The throttle valve 3, which is an output determination means of the engine 1, is not mechanically connected to the accelerator pedal 4 operated by the driver, but is separated therefrom, thereby opening the throttle valve 3 by the throttle actuator 5. Is made to electronically control the diagram.

The engine controller 6 has an engine torque control unit (not shown), an over-rotation preventing unit, an over-rotating prevention releasing unit, an engine torque increasing speed regulating unit, and an upper limit speed setting unit. The throttle actuator 5 controls the operation amount in accordance with the target throttle opening degree tTVO determined by the engine torque control section of the engine controller 6 as described later in accordance with the operation (driver required torque) of the accelerator pedal 4. Thereby, the opening degree of the throttle valve 3 is made to match the said target throttle opening degree tTVO, and the output of the engine 1 is controlled so that it may become a value according to operation of the accelerator pedal 4. On the other hand, it is possible to control by factors other than the accelerator pedal operation because of the control for reducing the throttle opening degree which prevents over-rotation of the engine by the over-rotation prevention part.

In addition, control by the engine controller 6 (for example, torque control of the engine, control to prevent over-rotation, control to release control to prevent over-rotation, control to regulate the speed of torque increase of the engine, etc.) may be used. It is not only performed by controlling the opening degree of the throttle valve which passed through (5), but although not shown in figure, it can also perform fuel cutoff control, ignition timing control, valve lift amount control of an intake / exhaust valve, etc.

The automatic transmission 2 is a well-known stepped automatic transmission. The automatic transmission 2 selects a corresponding shift stage by a combination of on and off of the shift solenoids 8 to 10 inserted into the control valve body 7 and sets the engine at a transmission ratio corresponding to the selected shift stage. The rotation of (1) is shifted and transmitted to the driving wheel of the vehicle.

The on / off control of the shift solenoids 8 to 10 is performed by the transmission controller 11 as follows.

That is, the transmission controller 11 has a fastening pressure control and a fastening pressure setting unit not shown in the drawing. The transmission controller 11 also allows the driver to park (P) range, retract drive (R) range, neutral (N) range, automatic transmission (D) range, engine brake (L) range, manual transmission (M) range (manual). The selection range signal from the shift lever 12 to be operated is input in accordance with which one is desired.

At this time, if a range in which the automatic transmission 2 is to be made impossible to transmit power is selected, the automatic transmission 2 is made neutral by turning off the shift solenoids 8 to 10, and the automatic transmission 2 is turned off. When the range to be in the power transmission state is selected, the shift solenoids 8 to 10 are turned on and off so that the automatic transmission 2 is in an electric state according to the selected range.

The operation when the automatic shift D range and the manual shift M range (manual shift mode) according to the present invention are selected will be described below.

In the case where the former automatic shift (D) range is selected, the transmission controller 11 shifts a suitable shift based on the predetermined shift map from the vehicle driving state (vehicle speed VSP, accelerator opening degree, etc., described later). The stage is determined, and the shift solenoids 8 to 10 are turned on and off so that the shift from the current selected shift stage to the appropriate shift stage is performed.

If the latter manual shift (M) range (manual shift mode) has been selected, the transmission controller 11 will change the current shift stage when there is a manual upshift command via the shift lever 12 or a manual downshift command. The shift solenoids 8 to 10 are switched on and off so as to shift from the first gear to the gear shift stage of the first stage up or down, and the shift solenoids 8 to 10 are executed until the next manual upshift command or manual downshift command is made. ) To maintain the on-off state and maintain the shift stage after switching.

The engine controller 6 and the transmission controller 11 control the engine 1 and the automatic transmission 2 described above, respectively, and communicate with each other not only the input information but also the calculation result. ) And the automatic transmission 2 are cooperatively controlled.

Therefore, as input information common to the engine controller 6 and the transmission controller 11, in addition to the above-mentioned selection range signal from the shift lever 12, manual upshift command and manual downshift command,

A signal from the accelerator opening sensor 13 for detecting the depression amount (acceleration opening) APO of the accelerator pedal 4,

A signal from the input rotation sensor 14 which detects the input rotation speed Ni of the automatic transmission 2,

A signal from the engine rotation sensor 15 that detects the engine speed Ne,

A signal from the output rotation sensor 16 which detects the output rotation speed No of the automatic transmission 2,

A signal from the vehicle speed sensor 17 that detects the vehicle speed VSP,

The signal from the throttle opening degree sensor 18 which detects the throttle opening degree TVO of the throttle valve 3 is input.

As described above, the transmission controller 11 determines a target shift stage suitable for the current driving state based on the predetermined shift map from the accelerator opening degree (APO) and the vehicle speed (VSP), or performs manual upshift command or manual downshift. The target shift stage corresponding to the command is determined, and the shift solenoids 8 to 10 are switched on and off so that the shift from the current selected shift stage to the target shift stage is performed.

In addition, the fastening pressure control part of the transmission controller 11 also performs the function of controlling the fastening pressure of a fastening side friction element and a release friction element via shift solenoids 8-10 at the time of the said shift.

In order to achieve the object of the present invention, the engine controller 6 executes the control program shown in FIG. 2 to determine the target throttle opening degree tTVO, and controls to prevent over-rotation of the engine targeted by the present invention. To perform.

In step S1, it is checked whether the selection range is a manual shift range (manual shift mode),

In step S2, it is checked whether the control which prevents over rotation of an engine is performed,

In step S3, it is checked whether there exists a manual upshift command.

When it is determined in step S1 that it is not the manual shift range (manual shift mode), when it is determined in step S2 that it is not in control to prevent over-rotation, or when it is determined in step S3 that there is no manual upshift command,

Since the control program of FIG. 2 which does not generate | occur | produce the technical subject which this invention intends to achieve and implement | achieves this subject is unnecessary, control is terminated as it is.

However, when it is determined in step S1 that it is a manual shift range (manual shift mode), and in step S2 that it is in control to prevent over-rotation, and when it is determined in step S3 that there is a manual upshift command,

Since the technical problem to be solved by the present invention is generated, the control proceeds to step S4 to step S9 in order to solve this problem, and control to prevent over-rotation of the engine after the manual upshift is performed as follows.

In step S4, the effective transmission ratio (i) = Ni / No and the upshift type (1 → 2, 2 → 3, 3 → 4, etc.) represented by the transmission input / output rotation ratio are stored in advance in a two-dimensional map, and these combinations are stored in advance. Of the upper limit value (DeltaTeLMT) regarding the engine torque increasing speed at the time of releasing the control which prevents over-rotation every time, it reads corresponding to the combination of the effective speed ratio i and an upshift gear type.

In step S5, the required engine torque TeOVRLMT of the control for preventing over-rotation of the engine that is requested by the control for preventing over-rotation of the engine determined in step S2 is read.

The engine torque TeOVRLMT of the control which prevents over-rotation of the engine read out in step S5 is demonstrated by FIG. 3, as apparent from the determination result of step S1-step S3. Target engine during incremental return from instantaneous t3 'at which the engine speed Ne decreases at the start of the upshift in response to the manual upshift command issued to instantaneous t2 during the control to be prevented, and the control to prevent over-rotation is released. It corresponds to torque tTe.

In step S6, the engine after the instantaneous time t3 'which releases the change rate of the requested engine torque TeOVRLMT of control which prevents over-rotation of the engine read in step S, ie, control which prevents over-rotation of FIG. The torque increase speed d / dt (TeOVRLMT) is calculated, and it is checked whether or not this is faster than the engine speed increase speed upper limit value? TeLMT at the time of releasing the control for preventing over-rotation read in step S4.

If it is not early, in step S7, the requested engine torque (TeOVRLMT) of the control which prevents over-rotation of the engine read in step S5 by the upper limit speed setting unit as it is is required. TeOVRLMT) and the target engine torque tTe after the instantaneous time t3 'which releases the control which prevents over-rotation of FIG. 3 from the requested engine torque TeOVRLMT at the time of canceling control which prevents the over-rotation determined in this way. )

The engine controller 6 outputs the target throttle opening degree tTVO to the throttle actuator 5 for realizing the target engine torque tTe = TeOVRLMT based on the current engine speed Ne. (TVO) matches the target throttle opening degree tTVO, whereby target engine torque tTe = TeOVRLMT can be realized.

The engine torque when the increase speed d / dt (TeOVRLMT) of the engine torque after the instantaneous time t3 'releasing the control to prevent the over-rotation of FIG. 3 is released in step S6 is released. When judging that it is faster than the increase rate upper limit (ΔTeLMT),

In step S8, to prevent the limited over-rotation as limited by the increase-speed upper limit value ΔTeLMT of the engine torque at the time of releasing the control for preventing the over-rotation of the increase speed d / dt of the engine torque. The requested engine torque TeOVRHLMT at the time of releasing control is calculated, and it is set to the required engine torque TeOVRLMT at the time of releasing control to prevent over-rotation.

Then, the target engine torque tTe after the instantaneous time t3 'of releasing the control for preventing over-rotation of FIG. 3 from the required engine torque TeOVRLMT = TeOVRHLMT when releasing the control for preventing over-rotation determined as described above. Shall be.

The engine controller 6 outputs a target throttle opening degree tTVO to the throttle actuator 5 for realizing such a target engine torque tTe = TeOVRHLMT based on the current engine speed Ne. (TVO) matches the target throttle opening degree tTVO, whereby target engine torque tTe = TeOVRHLMT can be realized. In other words, regulating the increase speed means that the engine torque command value is calculated so that the speed of opening the throttle valve is slower than when the normal accelerator pedal is operated, and the throttle opening degree is adjusted to correspond to the torque command value. To control.

In step S9, when the fastening pressure setting part releases the control which prevents over-rotation of the fastening pressure Pc of the fastening side friction element after instantaneous t3 'which cancels the control which prevents over-rotation of FIG. The value is replaced with the value read from the dedicated map when the value is corrected or the control for preventing over-rotation is released.

At the time of these corrections and replacements, the tightening pressure Pc of the fastening-side friction element after the instantaneous t3 'for releasing the control to prevent over-rotation is the engine torque Te, the throttle opening degree TVO and the accelerator opening. To be in accordance with the APO,

This fastening pressure Pc is made higher than the ratio with respect to normal engine torque as shown by a broken line, for example, as shown by a solid line after instantaneous time t3 'which release | releases the control which prevents over-rotation of FIG.

The control for preventing the above-mentioned rotation by the steps S4 to S9 is continuously executed until it is determined in step S10 that the control should be terminated.

Whether or not the control should be terminated here, for example, it is judged that the control should be terminated when the allowable time elapses from the end of the shift in which the effective shift ratio represented by the rotation ratio (Ni / No) of the input shaft and the output shaft of the transmission becomes the shift ratio after shifting. Can be.

According to this embodiment described above, as shown in FIG. 3, manual upshifting is performed during the control to prevent over-rotation of the engine (instantaneous t3), and the over-rotation is prevented at the subsequent decrease in the engine speed Ne. To increase the speed of the target engine torque tTe when the control is released and the opening degree of the throttle valve increases and returns (after t3 '). In step S6 and step S8, when the control to prevent over-rotation is released. In order to limit and suppress the increase of the engine torque by the upper limit value ΔTeLMT, the target engine torque tTe after the instantaneous t3 'for releasing the control to prevent over-rotation is released. As the required engine torque (TeOVRHLMT),

Increasing the engine torque by increasing the opening degree of the throttle valve in response to the release of the control to prevent over-rotation. The return of the engine is steep with respect to the increase in the tightening pressure Pc of the friction element on the fastening side responsible for the manual upshift. Can alleviate

The increase in the tightening pressure Pc of the friction element on the fastening side is alleviated by the delay of the increase and return of the engine torque, and the engine rotation is alleviated by reducing the flare with instability such as the broken line of the engine speed Ne. The number Ne can be changed smoothly as shown by the solid line.

Thus, as shown in Fig. 3, the instantaneous t3 'releasing the control to prevent over-rotation comes earlier than the instantaneous t3 releasing the conventional control to prevent over-rotation, and at the same time the rotation ratio (Ni Instantaneous t4 'at which the effective shift ratio i indicated by (No) reaches the shift ratio after the shift is completed earlier than the instantaneous t4 at which the conventional shift ends,

It is possible to avoid lengthening the shift time of the manual upshift during the control to prevent over-rotation and to suppress the response delay of the shift.

For the same reason, the fastening pressure Pc of the friction element on the fastening side does not cause a rapid drop, and because of this rapid drop, the vehicle acceleration G conventionally causes a time series change indicated by the broken line in FIG. Although the rapid reduction shift shock of the vehicle was generated, the fastening pressure Pc did not cause the rapid decrease, so that the vehicle acceleration G changed in time series as shown by the solid line in FIG. 3, and the rapid reduction shift shock of the manual upshift was suppressed. can do.

In addition, in step S9 of FIG. 2, as shown by the solid line, the fastening pressure Pc of the friction element of the fastening side after instantaneous time t3 'which cancel | releases the control which prevents over-rotation of FIG. 3 is prevented. Since the ratio by the engine torque of the normal clamping pressure Pc in the case that control is not performed is made high and it is made higher than the conventional clamping pressure Pc shown with a broken line, a shift response for the following reasons. Can improve.

That is, since the engine torque is lowered during over-rotation prevention, immediately after instantaneous t2 when the manual upshift is commanded, the friction element on the fastening side proceeds to fastening at a low fastening pressure Pc corresponding to this low engine torque, and thus manual The time (torque phase time) from the instantaneous t2 to which the upshift is commanded to the instantaneous t3 'at which the decrease of the engine speed Ne occurs due to the progress of the manual upshift tends to be long. In contrast, in the present embodiment, as described above, the tightening pressure Pc increases the ratio of the torque to the engine torque more than usual, so that the fastening of the friction element on the fastening side proceeds quickly and the torque phase time can be shortened.

In addition, when the control to prevent over-rotation is released (t3 '), the speed of increase of the suppressed target engine torque tTe also lowers the tightening pressure Pc determined according to the engine torque, and the manual upshift It tends to lengthen the time (inertia phase time) from the instantaneous t3 'from which the engine revolution speed Ne decreases by the progression to the time when the shift ends t4', but as described above, the engine torque of the tightening pressure Pc is increased. When the ratio is higher than usual, the fastening of the friction element on the fastening side proceeds quickly and the inertia phase time can be shortened.

As described above, when the tightening pressure Pc is made higher than usual when the control for preventing over-rotation is released (t3 '), both the torque phase time and the inertia phase time are shortened. Can be suppressed and the increase speed of the target engine torque tTe is suppressed after the release of the control to prevent over-rotation (t3 '). Since the tightening pressure Pc is determined in accordance with the engine torque, the tightening pressure Pc tends to be lowered, but there is no decrease in the shift response, which can be improved.

Also, the upper limit value ΔTeLMT of the increase in the engine torque determined in step S4 of FIG. 2 is before and after the effective speed ratio i, which is represented by the rotational speed ratio Ni / No of the input shaft and the output shaft of the transmission, becomes a predetermined speed ratio. You can do it differently. In other words, the increase speed upper limit value? TeLMT is set before and after completion of the shift by the automatic transmission.

In this case, the predetermined speed ratio is the speed ratio after shift after manual upshift, and as shown in Fig. 4, the engine torque increase speed upper limit value ΔTeLMT is changed before and after the actual shift end t4 'as shown in FIG. The upper limit of the increase speed of the engine torque after t4 ') can be made larger than the upper limit of the increase speed (ΔTeLMT) = ΔTeLMT (S) of the engine torque before the end of the actual shift (t4'), such as ΔTeLMT = ΔTeLMT (L).

In this way, when the upper limit speed ΔTeLMT of the engine torque is determined, the upper limit speed ΔTeLMT of the engine torque before (during shifting) at the end of the actual shift t4 '= ΔTeLMT (S) is the action of the present invention. The upper limit of the speed of increase of the engine torque (ΔTeLMT) = ΔTeLMT (L) after the end of stall (t4 '), which is determined by the speed of increase of the engine torque which is not very good in achieving the effect, and which is not involved in this action effect is possible. The control is terminated at an early stage to determine the speed at which the control end instantaneously reaches t5 ',

Thereby, while achieving the above-mentioned effect of this invention, the control which prevents over-rotation is terminated as early as possible, and it can avoid that control unnecessarily long.

The upper limit value ΔTeLMT of the increase in the engine torque determined in step S4 of FIG. 2 is set such that the effective shift ratio i represented by the rotational ratio ratio Ni / No of the input shaft and the output shaft of the transmission is different for each shift type of the manual upshift. You can do it differently before and after the speed ratio. That is, the increase speed upper limit value ΔTeLMT can be set in accordance with the speed ratio after completion of the shift of the automatic transmission.

In this case, the predetermined speed ratio is set to a speed ratio closer to the speed ratio before the shift than the speed ratio after the manual shift after manual upshift, and as shown in Fig. 5, before the instantaneous t4 '' at which the effective speed ratio i becomes this set speed ratio. The increase speed upper limit value (ΔTeLMT) of the engine torque is changed differently after the shifting electric current) and later (late shift), and the increase speed upper limit value of the engine torque of the shift electric speed is increased, such as ΔTeLMT = ΔTeLMT (L). It can be made larger than upper limit value (DELTA) TeLMT = (DELTA) TeLMT (S).

Thus, when determining the upper limit of the increase speed of the engine torque ΔTeLMT, the target engine torque tTe in the inertia phase from the instantaneous t3 'to the end of the shifting instantaneous time t4' where the effective shift ratio i becomes the shift ratio after shifting is determined. It can be made larger than the target engine torque shown by the broken line by the Example shown in FIG.

As a result, in the present embodiment, the vehicle acceleration G can be higher than that shown by the broken line according to the embodiment shown in FIG. 4, and in the embodiment shown in FIG. 4, the vehicle acceleration G is shown as the broken line. Although it becomes discontinuous so that it may be stabilized with the acceleration after shifting once after sudden dropping, in this embodiment, vehicle acceleration G can be stabilized with the acceleration after shifting without dropping, and a feeling of continuity of acceleration can be obtained.

In step S9 of Fig. 2, as described above with respect to Fig. 3, the ratio of the fastening pressure Pc of the friction element on the fastening side to the engine torque after the instantaneous time t3 'of releasing the control to prevent over-rotation is shown. Although the countermeasure to improve a shift response is made by making it higher than usual,

As described above, when the tightening pressure Pc is made higher than normal after t3 'at the moment of releasing the control to prevent over-rotation, the tightening pressure Pc is determined as shown in step S9 of FIG. As described above, it is practical to realize an increase in the clamping pressure Pc by similarly changing the engine torque Te, the throttle opening degree TVO, and the accelerator opening degree APO, which are control factors.

Here, a detailed description will be made based on FIG. 6, which is a time chart when the engine torque is similarly changed to realize a rise in the tightening pressure Pc.

FIG. 6 shows a case where the ratio of the engine torque is higher than the normal value in which the fastening pressure Pc is indicated by the broken line, as shown by the solid line in FIG. 4 in the case of performing control to prevent the over-rotation of the engine shown in FIG. This is a time chart when the engine torque is changed similarly to realize the increase in the tightening pressure Pc.

The engine torque Te used for determining the tightening pressure Pc is normally indicated by a broken line in addition to the control for preventing over-rotation, but the engine torque Te for determining the tightening pressure after instantaneous t2 when a manual upshift is commanded. ) Is raised to a predetermined value at the time of releasing the control to prevent over-rotation similarly to the solid line, and this instantaneously coincides with the engine torque Teo for determining the tightening pressure shown by the broken line as usual. Thereafter, the engine torque Te for determining the tightening pressure is switched from the predetermined value at the time of releasing the control to prevent over-rotation from the predetermined value to a higher value than usual.

The target value of the tightening pressure Pc is determined based on the similar engine torque Te for determining the tightening pressure thus determined, and the tightening pressure Pc is controlled to the solid line in FIG. 6 by controlling the tightening pressure Pc to be the target value. As shown, it can be higher than the ratio with respect to the engine torque of the normal value shown with a broken line.

In addition, in the above embodiment, in the control for preventing over-rotation of the engine, the case in which the target torque of the engine is feedback-controlled so as to keep the engine speed constant is explained. Instead of keeping the rotational speed constant, it is also applicable to the case where the target torque of the engine is suppressed and the rotational speed of the engine is lowered when the rotational speed of the engine reaches a predetermined value or more. In addition, although the above embodiment has described the case where the over-rotation prevention device operates in the manual mode of the automatic transmission, the over-rotation prevention device of the engine of the present invention can be applied also in the automatic shift mode. In addition, although the above embodiment has been described by using an automatic transmission of a stepped stage, the over-rotation preventing device of the engine of the present invention can be applied to a continuously automatic transmission (CVT, etc.).

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a system diagram showing a vehicle power train with a control system having a control device for preventing over-rotation of an engine according to an embodiment of the present invention.

Fig. 2 is a flowchart showing a control program when the engine controller in the power train control system of Fig. 1 obtains the target engine torque for preventing over-rotation of the engine and the fastening pressure of the fastening side friction element.

FIG. 3 is an operation time chart when the control program shown in FIG. 2 is executed;

4 is a time chart as in FIG. 3 showing another embodiment of the present invention;

Fig. 5 is a time chart as in Fig. 4 showing yet another embodiment of the present invention.

Fig. 6 is a time chart as in Fig. 4 showing yet another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: engine

2: automatic transmission

3: throttle valve

4: accelerator pedal

5: throttle actuator

6: engine controller

8 to 10: shift solenoid

11: transmission controller

12: shift lever

Claims (4)

It is an engine over-rotation prevention device that prevents over-rotation of the engine driving the drive wheels through an automatic transmission, An engine torque control unit that controls the torque of the engine based on a driver's requested torque; A rotation speed sensor detecting a rotation speed of the engine; An over-rotation preventing unit that suppresses the torque controlled by the engine torque control unit on the basis of the detected rotation speed of the engine and prevents over-rotation of the engine; An over-rotation prevention releasing portion for releasing the suppression of torque by the over-rotation preventing portion when the rotation speed of the engine falls below a predetermined value; And an engine torque increase speed regulating unit that regulates an increase speed of the torque when the torque is increased by releasing the suppression of the torque by the over-rotation prevention release unit during shifting by the automatic transmission. The automatic transmission, Friction elements for shifting, A fastening pressure control unit controlling the fastening state and the release state of the friction element by a fastening pressure; A fastening pressure setting unit for setting a fastening pressure based on the torque of the engine, And the tightening pressure setting unit sets a higher tightening pressure during control to prevent over-rotation than when the control to prevent over-rotation by the over-rotation preventing unit is not performed. The engine rotation preventing apparatus of claim 1, wherein the engine torque increasing speed regulating unit varies the degree of suppression of the torque before and after completion of the shift by the automatic transmission. The engine rotation preventing apparatus according to claim 1, wherein the engine torque increasing speed regulating unit varies the degree of suppression of the torque according to the speed ratio after completion of the shift by the automatic transmission. The method of claim 1, wherein the tightening pressure setting unit sets a tightening pressure on the basis of a torque obtained by incrementally correcting the suppressed torque, unlike the torque of the engine suppressed by the over-rotation preventing unit. Anti-overturning device of the engine.

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