JPH0424255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a method for decelerating a vehicle that is driven by power from an engine equipped with a fuel cut device through an automatic transmission capable of appropriately limiting slip between the input and output elements of a torque converter. This invention relates to an operation control device.

(Prior art) Automatic transmissions cannot avoid deterioration of power transmission efficiency due to relative rotation (slip) between the input and output elements of the torque converter, and the torque increase function and torque fluctuation absorption function of the torque converter are difficult to avoid. Automatic transmissions of the type that are capable of appropriately limiting slip between the input and output elements by means of a direct coupling clutch according to the driving conditions of the vehicle to meet the demands are becoming popular.

By the way, in such an automatic transmission, if the direct coupling clutch was operating when the engine accelerator pedal was released, then the rapidly increasing engine torque fluctuation would be transmitted from the engine to the subsequent transmission system via the operating direct coupling clutch. It is transmitted as is, causing vibration. Therefore, conventionally, during coasting (deceleration) driving from moment _t1 when the accelerator pedal is released as shown by A in Fig. 12 to moment _t2 when it is depressed again, the torque converter is directly connected as shown by B in the figure A control strategy was employed for a converter condition in which the clutch was deactivated (non-slip condition).

However, with this control method, the torque converter is kept in the converter state throughout deceleration operation, and during this period, the fuel supply to the engine is usually interrupted by the fuel cut device as shown below, so the engine rotational speed is greatly reduced as shown by C in the figure.

Here, considering the fuel cut device installed in the engine for fuel efficiency and exhaust gas countermeasures, this fuel cut device is designed to keep the engine speed at a certain rotation speed ( If you shift to deceleration operation while the engine is operating at a speed higher than the fuel cut speed, the fuel supply to the engine will be cut off (fuel cut) because power from the engine is not needed, and the engine speed will drop to a certain speed (for example, the fuel cut speed). When the engine speed drops below the fuel recovery rotation speed (as shown by _N1 in Figure 12), some engines restart the fuel supply to the engine (fuel recovery) to prevent the engine from stalling.

By the way, when the engine speed decreases significantly as shown in C in Fig. 12, the fuel cut time T _F1 becomes extremely short as shown in Fig. 12, and the fuel cut device does not have sufficient fuel efficiency improvement effect and exhaust countermeasure effect. It ceases to be something.

In order to solve this problem, it is possible to use the slip control technique disclosed in Japanese Patent Application Laid-Open No. 58-68539. This technique puts the torque converter in the converter state only during that period of time, from the viewpoint that engine torque fluctuations will attenuate and become larger after a certain period of time has elapsed after transition to deceleration operation.

(Problems to be Solved by the Invention) However, it has been confirmed that the fuel cut time cannot be extended using only this technique for the following reasons. That is, since the fuel cut device stops supplying fuel to the engine at the same time as the start of deceleration operation, the engine speed increases as shown by C in FIG. (in time) and reaches the fuel recovery rpm. Once the engine speed reaches the fuel recovery speed, the fuel cut device performs fuel recovery, unless the engine speed reaches the fuel cut speed equal to or higher than the fuel recovery speed _N1 . Continue the state. Therefore, the fuel cut time remains at T _F1 in FIG. 12, and this cannot be extended only by the above technique.

(Means for Solving the Problem) In order to solve this problem, the present invention, as shown in the concept in FIG. A vehicle 7 is capable of running via an automatic transmission 6 in which the slip of a torque converter 4 can be appropriately limited by a direct coupling clutch 5 in response to power from an engine 3 whose supply is stopped.
, an accelerator pedal release detection means 8 for detecting the release of the accelerator pedal 1, a timing means 9 for measuring the duration of the release of the accelerator pedal, and the duration corresponding to the time during which torque fluctuations occur due to the release of the accelerator pedal. a direct coupling clutch control means 11 that weakens the engagement force of the direct coupling clutch 5 while indicating that the set time is less than 10, and then increases the engagement force; A fuel cut device control means 12 is provided which prevents the fuel supply from being stopped and then causes the fuel supply to be stopped.

(Function) During the set time after the transition to deceleration operation when the accelerator pedal 1 is released, the direct coupling clutch control means 11 reduces the engagement force of the direct coupling clutch 5 to put the torque converter 4 in the slip increasing state, thereby increasing the slippage of the accelerator pedal. Absorbs torque fluctuations caused by release. Then, during the set time, the fuel cut device control means 12 puts the fuel cut device 2 into a fuel cut prohibited state, so as to prevent the torque converter from increasing slip and the engine speed from decreasing rapidly (the engine speed does not change during the set time). (so that the number does not drop to the fuel recovery speed). Then, after the set time, the direct coupling clutch control means 11 controls the direct coupling clutch 5.
By increasing the tightening force of the engine, the torque converter 4 is brought into a slip decreasing state so that the engine speed gradually decreases along with the vehicle speed, thereby preventing a sudden drop in the engine speed. to run the fuel cut.

The increased slip state of the torque converter can absorb torque fluctuations at the beginning of deceleration operation and prevent vibrations from occurring. Since the fuel cut is prohibited during this time, the engine speed will not drop suddenly and reach the fuel recovery speed. After that, the torque converter is put into a slip reduction state, and the engine speed gradually decreases with the vehicle speed, preventing a sudden decrease.
During this time, the fuel cut device is operated to stop the fuel supply to the engine. When the slip of the torque converter is reduced, the engine speed decreases as the vehicle speed decreases, and even when the fuel cut is performed, the engine speed does not suddenly decrease, and the fuel cut time can be extended as a result. .

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 shows a slip-controlled torque converter 4 to be controlled by the device of the present invention, which comprises a pump impeller (input element) 4a, a turbine runner (output element) 4b, and a stator (reaction element) 4c, and further includes a directly coupled Built-in clutch 5. The pump impeller 4a is attached to a converter cover 4d.
drivingly coupled to the engine 3 (see Figure 1) via the
It is constantly rotated by this engine. Turbine runner 4b is riveted to turbine hub 13, drivingly coupling the turbine hub to torque converter output shaft 14. Furthermore, the stator 4c is connected to the one-way clutch 1.
5 on a hollow fixed shaft 16, a hydraulic oil supply passage 18 is provided between the shaft and a shaft 17 surrounding the shaft, and a hydraulic oil return passage 19 is provided between the shafts 14 and 16, respectively. Hydraulic oil from a passage 18 flows into the torque converter 4, and is then removed through a passage 19. However, there is a pressure holding valve (not shown) in the middle of the flow, and an internal converter chamber 20 of the torque converter 4 is provided.
is maintained at converter pressure Pc.

The direct coupling clutch 5 connects its inner periphery to the turbine hub 1.
3, and has a clutch facing 5a on the outer periphery of the converter chamber 2.
A lockup chamber 21 partitioned from 0 is defined between the converter cover 4d and the converter cover 4d. The direct coupling clutch 5 is normally drive-coupled to the turbine runner 4b via a torsional damper 22, and is connected to the lock-up chamber 2.
1 through the center hole 23 of the shaft 14 to the slip control valve 2
4 port 24a.

The direct coupling clutch 5 is operated and controlled by a slip control valve 24 and a lock-up solenoid 25, and the valve 24 has a port 24b and a drain port 24c in addition to a port 24a, and the converter pressure Pc is introduced into the port 24b. The spool 24d of the valve 24 connects the port 24a to the drain port 24c when going rightward to the upper half position in the figure, and connects the port 24a to the hole 23.
The circuit leading to the lock-up chamber 21 is brought to a pressure-free state, and the port 24a is connected to the port 24b when moving to the left to the lower half position in the figure, and a lock-up pressure equal to the converter pressure Pc is transferred from the port 24a to the lock-up chamber 21. PL/u is output, and port 24a is connected to ports 24b and 24c at an intermediate position to adjust the lock-up pressure PL/u from port 24a to a value corresponding to the spool position.

The position of the spool 24d is determined by the lockup pressure PL/u led to the chamber 24f by the passage 24e and the
The chamber 24g is determined by the control pressure Ps within 4g, and the chamber 24g leads the reference pressure (line pressure in the case of an automatic transmission) P _L through the orifice 27 through the passage 26 and communicates with the drain port 29 through the orifice 28. Then, the plunger 25a of the lock-up solenoid 25 is disposed opposite to the orifice 28, and this solenoid normally projects the plunger 25a to the right half position in the figure to close the orifice 28, and when energized, the plunger 25a moves to the left half position in the figure. The orifice 28 shall be opened by retreating to the lower position.

The slip-controlled torque converter described above operates as follows.

When the plunger 25a closes the orifice 28 due to deenergization of the lock-up solenoid 25, the control pressure Ps becomes equal to the reference pressure P _L , and the spool 24
Set d to the lower half position in the figure. Thus, the lockup pressure PL/u becomes equal to the converter pressure Pc, and the pressure inside the lockup chamber 21 becomes the same as that of the converter chamber 20. Therefore, the direct coupling clutch 5 is not pressed against the converter cover 4d, and the fastening force becomes zero, and the torque converter 4 transmits power in a so-called converter state. During this time, the lock-up pressure PL/u also reaches the chamber 24f of the valve 24 and opposes the control pressure Ps in the chamber 24g, but since Ps>PL/u,
The valve spool 24d can maintain the lower half position in the figure to maintain the torque converter in the converter state.

When the plunger 25a opens the orifice 28 by the activation of the lock-up solenoid 25, the control pressure Ps becomes zero, and the spool 24d opens the chamber 24f.
The lock-up pressure PL/u in the figure places it in the upper half position in the figure. Thus, the lock-up pressure PL/u is made zero, and the direct coupling clutch 5 is pressed against the converter cover 4d by the pressure Pc in the converter chamber 20, so that the fastening force becomes maximum. Therefore, the torque converter 4 transmits power in a so-called lock-up state in which no relative rotation occurs between the input and output elements 4a and 4b.

Then, the lock-up solenoid 25 is energized.
When deenergization is repeated and the energization time width is duty-controlled as described below, as the duty increases, the control pressure Ps decreases, and although the spool 24d allows the port 24a to communicate with both ports 24b and 24c, gradually decreasing the degree of communication with the port 24b,
The degree of communication with port 24c is gradually increased. Therefore, the lockup pressure PL/u changes to decrease as the duty increases, and by controlling the duty of the operating state of the direct coupling clutch 5 so that its coupling force changes, the torque converter 4 can be subjected to slip control.

In the present invention, the lock-up solenoid 2
5 is controlled by a microcomputer shown in FIG. 3 to enable slip control of the torque converter 4 as the object of the present invention.
1 to perform the fuel cut which is the object of the present invention. As usual, a microcomputer has a central processing unit (CPU) 30, a random access memory (RAM) 31, and a read-only memory (ROM) 32.
and input/output interface circuit (i/0) 33
It consists of

This microcomputer receives the engine rotational speed signal N _E from the engine rotational speed sensor 34, the rotational speed signal No. regarding the output shaft of the automatic transmission from the output shaft rotational speed sensor 35, and the accelerator pedal release signal Is output from the idle switch 36. and a gear position signal Gs of the transmission outputted from the gear position sensor 37, a signal related to the engine intake air amount Q detected by the intake air amount sensor 42, and a signal related to the engine cooling water temperature T _E detected by the water temperature sensor 43, respectively. The waveform is shaped by the waveform shaping circuit 38 and then input to the i/033, and the engine throttle opening signal TH from the throttle opening sensor 39 is converted into a digital signal by the A/D converter 33a and then input to the i/033. It is entered as 0.
Then, the microcomputer appropriately operates the lock-up solenoid 25 via the amplifier 40 based on the calculation results of these input signals, and
The fuel injection valve 41 is operated as appropriate.

For this purpose, the microcomputer executes the control program shown in FIGS. 4-8.

FIG. 4 shows an interrupt processing routine activated by the engine rotational speed signal N _E generated every time the engine is ignited, and calculates the engine rotational speed (torque converter input rotational speed) n _e from the time interval of interrupt generation. Figure 5 shows an interrupt handling routine that is activated by the output shaft rotational speed signal No. generated every revolution _of the automatic transmission output shaft. ), the gear position g of the transmission is detected from the signal Gs, and then the turbine runner 4b is multiplied by the gear ratio corresponding to this gear position g and the output shaft rotation speed n _p .
Calculate the rotation speed (torque converter output rotation speed) n _T.

FIG. 6 shows a regular interrupt routine that is processed every fixed time ΔT. First, in step 51, the throttle opening signal TH is A/D converted, and the throttle opening TH is read. In the next step 52, it is determined from the idle signal Is whether the idle switch 36 (see Fig. 3) is OFF or ON, and if the idle switch 36 is OFF and the accelerator pedal is depressed, control proceeds to step 53 and the following steps are performed. to perform slip control on the torque converter as usual.

That is, in step 53, the flag I is set to 0 to indicate that the engine is not decelerating, and the flag is also set to 0 to indicate that the fuel should not be cut.In the next step 54, the throttle opening TH and gear position are set to 0. g and vehicle speed V, it is determined whether the operating range in which the torque converter should be placed in the converter state is the operating range in which the torque converter should be in the lock-up state or the operating range in which slip control should be performed. If it is in the converter region, the output duty is set to 0% in step 55, and this is updated with the previous output duty in step 56. In this case, the lock-up solenoid 25 remains de-energized, allowing the torque converter to enter the converter state as desired, as previously described. If it is a lock-up area, set the output duty to 100% in step 57,
This is updated with the previous output duty in step 56. In this case, lockup solenoid 25 remains energized via amplifier 40, allowing the torque converter to be placed in lockup as desired, as previously described. If it is in the slip control region, the output duty is determined in step 58 by proportional (P) and integral (I) calculations based on the difference between the actual slip amount n _e -n _T of the torque converter and the set slip amount, and this is calculated in step 56 from the previous time. Update the output duty. In this case, the lockup solenoid 25 is repeatedly energized and deenergized in a time range corresponding to the output duty via the amplifier 40, and the torque converter can be subjected to slip control as described above. Since this control is PI control, the torque converter has a slip amount n _e
-n _T is brought to the set slip amount and is maintained at this set slip amount.

By the way, if it is determined in step 52 that the idle switch 36 (see FIG. 3) is ON and the accelerator pedal is released (decelerating operation), the control proceeds to step 59, where the purpose of the present invention is determined as follows. Torque converter slip control and fuel cut control for deceleration operation are performed as follows.

First, slip control will be explained. This is executed by the control program shown in FIG. This control program is executed, for example, every 10 msec, and first, in step 60, it is determined whether or not the flag is 1, that is, whether or not there was deceleration operation last time. If the flag=0, that is, immediately after deceleration operation, the flag is set to 1 to indicate that deceleration operation is in progress, and a counter for measuring the duration of deceleration operation is reset to 0 in step 61. In the next step 62, the output duty is set to 0%, and then in step 63, it is determined whether or not the engine speed n _e is greater than or equal to the fuel cut rotation speed N 〓 determined for each engine cooling water temperature T _E as shown in FIG. 9. If so, the fuel should be cut in step 64, so a flag is set to 1 to indicate this; otherwise, in step 65
Since the fuel should not be cut at this point, the flag is reset to 0 to indicate this.

If it is determined in step 60 that the deceleration operation was performed last time due to the flag = 1, the above-mentioned counter is incremented (stepped forward) in step 66.
However, in the next step 67, it is determined whether or not the flag is 1, that is, whether or not the fuel should be cut. If the fuel should not be cut off, it is determined in step 68 whether the engine speed n _e is greater than or equal to the fuel cut speed N 〓 determined for each engine cooling water temperature T _E as shown in FIG. At 69, the engine speed n _e is equal to the engine cooling water temperature as shown in Figure 9.
Determine whether or not the fuel recovery rotation speed N〓 determined for each T _E is higher than or not. In step 68, n _e ≧
If it is determined in step 69 that n _e ≧N, the fuel should be cut, so a flag is set to 1 in step 70 to indicate this, and in step 68 n _e <
If it is determined as N〓, or in step 69
If it is determined that n _e <N, the fuel should not be cut, so the flag is reset to 0 in step 71 or 72 to indicate this.

From steps 64, 65, 70, 71 or 72, control proceeds to step 73 where flag =
1, that is, whether fuel should be cut or not. If the fuel should not be cut (flag=0), the output duty is set to 0% in step 74, and this is updated in step 75, thereby bringing the torque converter into the converter state. If the fuel should be cut, it is determined in step 76 whether the deceleration duration time measured by the counter described above is longer than the set time T ₁ (400 msec, where the counter value is 40, for example), and if it is less than T ₁ . Steps 74, 75
puts the torque converter into the converter state. If _T1 or more, in step 77, the target slip amount of the torque converter is read from the table data corresponding to FIG. 10 based on the engine speed n _e . This target slip amount is determined by the above setting time.
After T ₁ has elapsed, the torque converter is made to correspond to a value that allows the torque converter to just absorb the different engine torque fluctuations for each engine rotational speed n _e . In the next step 78, the output duty is determined by PI calculation based on the difference between the actual slip amount n _e -n _T of the torque converter and the target slip amount, and then in step 75 the output duty is updated to lock up the lock-up solenoid 25. By driving the torque converter according to the updated duty, slip control can be performed to maintain the torque converter at the target slip amount.

If the above operation is shown in a time chart when both before and after the deceleration operation are in the lockup region, it is as shown by the solid line in FIG. During the set time _{T1 from the start of deceleration operation t1, the} output duty is kept at 0 as shown by D, and the torque converter is kept in the converter state by the non-operation of the direct coupling clutch 5 (see FIG. 2). In this way, the torque converter can reliably absorb large torque fluctuations at the beginning of deceleration operation and prevent vibrations from occurring. After the set time T ₁ , the output duty is changed as shown by E until the end of deceleration operation t ₂ , and the torque converter is
Feedback control is performed to achieve the target slip amount shown in the figure to bring the slip into a limited state. Since this target slip amount is determined as described above, the torque converter can absorb torque fluctuations exactly after the set time _T1 has elapsed, and vibrations can be prevented from occurring during this time as well.

Next, the fuel cut control which is the object of the present invention will be explained. This is executed by the control program shown in FIG. This control program is executed every revolution of the engine, and first, in step 80, the idle switch 36 is activated by the idle signal _IS.
Is it ON (deceleration driving after releasing the accelerator pedal)?
Determine whether it is OFF (power-on driving with the accelerator pedal depressed). If the vehicle is running with the power on, the normal fuel injection pulse width T _i is unconditionally calculated from the engine speed n _e , engine coolant temperature T _E , intake air amount Q, etc. in step 81 . Next step 8
By setting the pulse width T _i in step 2, the fuel injection valve 41 (see Fig. 3) is opened in synchronization with the rotation of the engine for the duration of the pulse width T _i , thereby supplying the optimal amount of fuel to the engine. You can run this engine by doing this.

When it is determined in step 80 that the operation is decelerated, it is determined in step 83 whether or not the flag is 1, that is, whether or not the fuel should be cut. If the flag = 0 and fuel should not be cut as described above with respect to FIG.
By executing step 2, fuel injection continues as usual.
If the flag = 1 and the fuel should be cut, then in step 84, it is determined based on the count value of the counter whether the deceleration operation continuation time is longer than the set time _T1 , and if it is less than _T1 , the step is stopped. By executing steps 81 and 82, a fuel cut is not performed, and if it is greater than or equal to _T1, the fuel injection pulse width T _i is set to 0 in step 85, and is set in the next step 82. When the pulse width T _i =0, the fuel injection valve 41 (see FIG. 3) is not opened at all, fuel supply to the engine is stopped, and the fuel is cut.

To explain the above operation with reference to FIG. 12, as shown by the solid line F, from the start of deceleration _t1 to the set time _T1 , even if the engine speed is at a value that requires fuel cut, fuel supply is continued without fuel cut. , the fuel cut is performed after the set time _T1 has elapsed. This fuel cut is continued until the engine speed becomes less than the fuel recovery speed _N1 and the flag is set to 0 as described above, and the fuel cut time becomes T _F2 .

By the way, during the set time _T1 , although the torque converter is brought into the converter state as shown by D, since the fuel cut is not performed as shown by F, the engine speed n _e decreases more gradually than the conventional C as shown by G during this time. Even after the set time T ₁ has elapsed, the fuel recovery rotation speed N ₁ is not reached. After that, the engine speed drops as shown by H due to the fuel cut, but due to the slip limit state of the torque converter shown as E, the engine speed increases to a value corresponding to the vehicle speed as shown in , and thereafter increases with the vehicle speed as shown in J. descend. Therefore, a considerable amount of time can be saved until the engine speed drops to the fuel recovery speed _N1 , and by cutting the fuel during this time, the fuel cut time T _F2 can be reduced to the conventional fuel cut time T _F1.
It can be extended even further.

In addition, the drop in engine speed that occurs after the slip limit state starts after the set time has elapsed.
This is due to the fact that the slip limit of the torque converter tends to be delayed in response to the fuel cut due to the response delay of the hydraulic system, but if the response delay of the hydraulic system is large, the engine speed will drop due to H. There is a concern that the fuel recovery rotational speed may drop to _N1 , making it impossible to achieve the above effects.

In order to eliminate such concerns, the control program shown in FIG. 8 can be replaced with the control program shown in FIG. 11. That is, if it is determined in step 80 that the vehicle is running with the power on, or in step 88
If it is determined in step 86 that the fuel should not be cut, a flag that becomes 1 during the fuel cut delay is reset to 0 in step 86, and then steps 81 and 82 are executed. Then, if it is determined in step 84 that the set time is less than _T1 ,
After setting the flag to 1 in step 87, steps 81 and 82 are executed. If it is determined in step 84 that the set time _T1 has elapsed,
In step 88, it is checked whether the flag is 1 or not, and if so, in step 89, the engine speed is set.
n _e is a predetermined amount to the fuel recovery rotation speed N _I
Determine whether the value exceeds the sum of 100 rpm. If not, the fuel cut is not executed in steps 81 and 82, and if it is exceeded, the flag is reset to 0 in step 90, and then the fuel cut is executed in steps 85 and 82. After the flag is reset in this way, step 88 suddenly jumps to step 85.
Even if the engine speed n _e becomes less than N _I + 100 rpm, this is the fuel recovery speed.
Continue fuel cut until it drops to N _I.

The above action will be explained with reference to FIG. 12, as shown by the dashed dotted line. That is, when the set time T ₁ has elapsed, K
As shown in the figure, the fuel cut has not yet been performed, and therefore the engine speed n _e does not drop H, but is reduced to L due to the slip limit E of the torque converter.
It rises like this. Then, the engine speed n _e is
Fuel cut is executed as shown in K at the instant t ₃ when N _I exceeds +100 rpm, and the fuel cut is changed to T ₂
You can only delay the time. Therefore, the drop H in the engine speed after the set time _T1 has elapsed is eliminated, and the above-mentioned concern that the engine speed drops to the fuel recovery speed _N1 and the effects of the present invention cannot be achieved can be resolved. .

FIGS. 13 and 14 show the torque converter in a case where the torque converter 4 has only two operating modes: it is brought into the converter state by releasing the direct coupling clutch 5, and it is brought into the lock-up state by completely engaging the direct coupling clutch 5. An example of fuel cut control is shown below.

FIG. 13 shows a control program for the torque converter, and this program is repeatedly executed, for example, every 10 msec. First, in step 91, it is determined based on the idle signal _IS whether the vehicle is running with power on, with the accelerator pedal depressed, or decelerating, with the accelerator pedal released. If the vehicle is running with the power on, a flag indicating deceleration operation is set to 0 in step 92, and then an output duty for normal lock-up control is determined in step 93. This control is based on predetermined table data from throttle opening TH, gear position g, and vehicle speed V to determine whether the torque converter should be in the converter state or not.
Determine whether the operating region should be locked up,
If it should be in converter state, set the output duty to 0.
%, or set the output duty to 100% if you want to lock it up. By setting the output duty in the next step 94, the lock-up solenoid 25 (see Figure 3) continues to be deenergized if the output duty is 0%, bringing the torque converter into the converter state as described above, and increasing the output duty.
If it is 100%, it will continue to be energized and the torque converter will be locked up as described above.

If it is determined in step 91 that the operation is decelerating, it is determined in step 95 whether or not the flag is 1, that is, whether or not it was in deceleration operation last time.If it is in deceleration operation this time, step 9
At step 6, a flag is set to 1 to indicate that deceleration operation is in progress, and at step 97, a counter for measuring the duration of deceleration operation is reset to 0, and then control proceeds to step 98. Flag at step 95 =
1, that is, when it is determined that the previous deceleration operation was in progress, the control proceeds directly to step 98.

In step 98, the above-mentioned counter is incremented, and in the next step 99, it is determined whether or not this counter indicates the set time _T1 or more. If the set time T is less than ₁ , step 100
In step 94, the output duty is set to 0%, and this is set in step 94 to bring the torque converter into the converter state. Setting time T ₁
When the vehicle speed V has elapsed, the vehicle speed V is increased in step 101.
Determine whether or not it is 20Km/h or more, and if V≧20Km/h, set the output duty to 100% in step 102,
By setting this in step 94, the torque converter is put into a lock-up state, and when V<20
Km/h, the fuel cut will not be executed even with this lockup, so step 10
By executing steps 0 and 94, emphasis is placed on putting the torque converter into the converter state and absorbing torque fluctuations during deceleration operation.

FIG. 14 shows a fuel cut control program, and this program is repeatedly executed every revolution of the engine. If it is determined in step 103 that the vehicle is running with the power on, the flag is set to 0 to indicate this in step 104, and the process continues in step 1.
In step 05, the flag is set to 0 to indicate that the fuel should not be cut. In step 106, the fuel injection pulse width T _i is calculated in the same manner as described above. By setting this pulse width T _{i in step 107, the fuel injection pulse width T i} is set in step 107. The fuel supply will continue as normal.

If deceleration operation is determined in step 103, it is determined in step 108 whether the flag was set to 1 or not to determine whether deceleration operation occurred last time. After setting the flag to 1 as shown, in step 110 it is determined whether the engine rotational speed n _e is greater than or equal to the fuel cut rotational speed N〓 in FIG.
If so, the fuel should be cut, so a flag is set to 1 to indicate this in step 111. If not, the fuel should not be cut, so steps 105 to 10 are performed.
Execute step 7. If it was determined in step 108 that the vehicle was in deceleration operation last time, it is determined in step 112 whether or not the fuel should have been cut last time based on whether the flag was set to 1 or not.
In step 3, it is determined whether the engine speed _{n e is} greater than or equal to the fuel recovery rotation speed N _I shown in FIG. Determine whether or not. If it is determined in step 113 that n _e ≧N〓,
Or if it is determined in step 114 that n _e ≧N〓,
You should cut the fuel, so step 111
If it is determined in step 113 that n _e <N〓, or if it is determined in step 114 that n _e <N〓, the fuel should not be cut, so steps 105 to 107 are selected.

When step 111 is selected and the fuel is to be cut, then in step 115 the counter determines the set time for the deceleration operation to continue.
Determine whether T ₁ +T ₂ has been reached. If the set time is not reached, the fuel cut is not executed in steps 106 and 107, and after the set time, the fuel injection pulse width T _i is set to 0 in step 116, and this is set in step 107 to execute the fuel cut.

The above-mentioned action is shown in an operation time chart as shown by the solid line in FIG. That is, during the set time _T1 from the start of deceleration operation _t1 , the torque converter is at D.
As shown by M, it is put into the converter state as in FIG. 12, and then, as shown by M, it is put into the lock-up state. As shown by K, the fuel cut is at t ₁ at the start of deceleration operation, similar to the dashed line in Fig. 12.
It is not executed until the instant t ₃ when the set time T ₁ +T ₂ has elapsed, and then it is executed during the period T _F2 ′. Therefore,
The engine speeds gradually decrease as shown in G, N, and O (G is the same as in Fig. 12, and N and O are in the lock-up state in this case, so they are slightly higher than L and J in Fig. 12). As in the example, the fuel cut time T _F2 ' can be significantly extended compared to the conventional time T _F1 .

In the above embodiment, the time T ₂ needs to correspond to the response delay time of the hydraulic system for changing the torque converter from the converter state to the lock-up state for the reason described above with reference to FIG. It varies depending on individual differences and the viscosity of the hydraulic oil, and it is difficult to provide accurate correspondence in the above embodiment. If it is desired to solve this problem, the purpose can be achieved by using the control program shown in FIG. 16 instead of the control programs shown in FIGS. 13 and 14.

The control program shown in FIG. 16 is repeatedly executed every revolution of the engine, and when it is determined in step 120 that the vehicle is running with power on by depressing the accelerator pedal, the flag is set to 0 in step 121 to indicate this. At the same time, since the fuel should not be cut, the flag is also set to 0, and in the next step 122, the counter that measures the duration of deceleration operation after the accelerator pedal is released is set to 0. Thereafter, normal lock-up control is executed in step 123, and fuel injection pulse width T _i is calculated in step 124, thereby supplying fuel to the engine as usual.

If step 120 determines that the operation is deceleration, steps 125 to 131 check whether the fuel should be cut, as in FIG. 14, and if the fuel should be cut, step 1
Set the flag to 1 at step 32, and set the flag to 0 at step 133 if the fuel should not be cut.
Make it. In a state where fuel cut should not be performed, it is not possible to extend the fuel cut time even with the control according to the present invention. Therefore, with emphasis on vibration prevention, the torque converter is set to the converter state with an output duty of 0% in step 134, and then, in step 124, the torque converter is set to the converter state. Continue fuel supply to meet demand. In a state where a fuel cut is to be made, the counter is incremented (stepped forward) in step 135, and then it is determined in step 136 whether or not this counter indicates a set time T1 _or more. Step 1 until the set time T ₁ is reached.
34 and 124, the torque converter is placed in the converter state, fuel supply to the engine is continued, and after the set time _T1 has elapsed, the output duty is set to 100% in step 137, thereby shifting the torque converter to the lock-up state. . Since this transition is not completed immediately due to the response delay of the hydraulic system, it is determined in step 138 whether or not it has been completed.
The determination is made based on whether the input and output rotational speeds n _e and n _T of the torque converter match. While the lockup is not completed (n _e ≠ n _T ), select step 124 to prevent the fuel cut from being executed, and after the lockup is completed (n _e = n _T ), the fuel injection pulse width T _i is set to 0 in step 139. This causes the fuel cut to be executed.

In this example, the same effects as those described above with reference to FIG. It can be played even more reliably.

(Effects of the Invention) Thus, as described above, the deceleration operation control device of the present invention brings the torque converter 4 into the slip increasing state during the set time _T1 from the start of deceleration operation, and continues to supply fuel to the engine (does not cut fuel). Since the torque converter is brought into the slip reduction state after a set time and the fuel cut is performed, the following effects can be obtained.

That is, the increased slip state of the torque converter can absorb large torque fluctuations at the beginning of deceleration operation (during set time _T1 ) and prevent vibrations from occurring. During this time, by not performing a fuel cut, the engine speed will not suddenly decrease and reach the fuel recovery speed N〓. After that, by putting the torque converter in the slip reduction state, the engine speed increases to a value corresponding to the vehicle speed, and then decreases as the vehicle speed decreases, allowing time for the engine speed to drop to the fuel recovery speed N. Since the fuel cut is executed during this time, the fuel cut time can be significantly extended.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of the device of the present invention, FIG. 2 is a system diagram illustrating a torque converter to be subjected to slip control by the device of the present invention, and FIG. 3 is a block diagram of a microcomputer showing an example of the device of the present invention.
4 to 8 are flowcharts showing the control program of the microcomputer, FIG. 9 is a characteristic diagram of fuel cut rotation speed and fuel recovery rotation speed, and FIG. 10 is a characteristic diagram of torque converter target slip amount. 11 is a flowchart showing a modification of the control program shown in FIG. 8, FIG. 12 is an operation time chart according to the example of FIGS. 4 to 8 and FIG. 11, and FIGS. 13 and 14 are control programs. A flowchart showing other examples of
FIG. 15 is an operation time chart for the same example, the first
FIG. 6 is a flowchart showing a modification of the control program shown in FIGS. 13 and 14. 1...Accelerator pedal, 2...Fuel cut device, 3...Engine, 4...Torque converter, 5...Direct clutch, 6...Automatic transmission, 7
...Vehicle, 8...Accelerator pedal release detection means,
9... Timing means, 10, T ₁ ... Setting time, 11
... Direct coupling clutch control means, 12 ... Fuel cut device control means, 13 ... Turbine hub, 1
4...Torque converter output shaft, 20...Converter chamber, 21...Lockup chamber, 22...Torsional damper, 24...Slip control valve, 25
... Lock-up solenoid, 27, 28 ... Orifice, 30 ... Central processing unit, 31 ...
Random access memory, 32... Read-only memory, 33... Input/output interface circuit, 34
...Engine speed sensor, 35...Torque converter output speed sensor, 36...Idle switch, 37...Gear position sensor, 38...Waveform shaping circuit, 39...Throttle opening sensor, 40...
...Amplifier, 41...Fuel injection valve, 42...Intake air amount sensor, 43...Water temperature sensor.

Claims (1)

[Scope of Claims] 1. During deceleration driving with the accelerator pedal released, fuel supply is stopped by the fuel cut device under predetermined operating conditions.When receiving power from the engine, the slip of the torque converter is appropriately controlled by the direct coupling clutch. In a vehicle that can be driven via an automatic transmission that may be restricted, the vehicle comprises: an accelerator pedal release detection means for detecting the release of the accelerator pedal; a timing means for measuring the duration of the release of the accelerator pedal; direct coupling clutch control means for weakening the engagement force of the direct coupling clutch for a period of time less than a set time corresponding to the time during which torque fluctuations occur due to the occurrence of torque fluctuations, and increasing the engagement force after the duration exceeds the set time; and a fuel cut device control means that does not cause the fuel cut device to stop supplying fuel for a period of less than a set time and causes the fuel cut device to stop supplying fuel after the set time has elapsed. Vehicle deceleration control device.