JP2819965B2 - Automatic engine braking force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic engine braking force control device, and more particularly to an automatic engine braking force control device for automatically increasing an engine braking force by downshifting and throttle control.

[0002]

2. Description of the Related Art Automatic vehicles equipped with an automatic transmission having a plurality of gear positions are often used. Generally, such automatic transmissions have a gear position based on an accelerator operation amount or a throttle valve opening and a vehicle speed. It has been changed. FIG. 10 is an example of a shift map of an automatic transmission having four shift stages, in which the shift stages are switched based on the accelerator operation amount and the vehicle speed. It is a shift map on a downshift side. Since such a shift map normally shifts up according to the vehicle speed even when the accelerator operation amount is zero, that is, in the OFF state, a sufficient engine braking force can be obtained even when the accelerator pedal is released on a downhill. If the vehicle speed increases without being obtained, there is a problem that the engine brake force is further reduced due to an upshift. As a countermeasure, when the acceleration of the vehicle is non-negative or the vehicle speed keeps increasing for a certain period of time while the accelerator is off, the engine braking force is increased by downshifting to increase the gear ratio of the automatic transmission. For example, Japanese Patent Application Laid-Open Nos. Sho 62-246650 and
It is disclosed in, for example, JP-A-1-103044.

When the downshift is performed to increase the engine braking force when the accelerator is in the off state, the speed ratio of the automatic transmission is increased in the downshift, so the engine speed must be increased accordingly. There is. In this case, since the throttle valve is normally closed at the time of such engine braking, the torque on the output side is transmitted by torque transmission of a low-speed gear side, such as a hydraulic clutch or a brake, for achieving the gear position after the downshift. Is transmitted to the engine side, thereby increasing the rotation speed of the engine. As a result, the shift time is longer than the downshift at power-on, the amount of friction energy of the hydraulic clutch and brake is increased, the life of the friction material is reduced, and the inertia torque when increasing the engine speed is reduced. Has appeared as braking torque of the vehicle, and there has been a problem that the engine braking force temporarily increases to cause a shift shock. Also, if a downshift is performed with the throttle fully closed, the engine braking force will increase sharply in response to a change in the gear ratio, causing a shock and poor ride comfort. May be required.

On the other hand, the applicant of the present invention controls the opening of the throttle valve during downshifting for increasing the engine braking force so that, for example, the driving force before and after the downshift becomes substantially the same, while controlling the opening of the throttle valve. It has been proposed in Japanese Patent Application Nos. 4-186201 and 4-203104 that the throttle control is performed so as to reduce the throttle valve opening after the downshift is completed. According to such an engine braking force automatic control device, it is possible to reduce a shift time required for downshifting and to suppress a sudden increase in engine braking force.

[0005]

However, while such an automatic control of the engine braking force is performed, the fuel supply to the engine when the throttle valve is almost fully closed for the purpose of improving the fuel efficiency and preventing the catalyst from overheating is performed. In a vehicle in which fuel cut control is performed in parallel, the fuel supply to the engine is shut off by the fuel cut control when the throttle valve is almost fully closed, and the throttle valve is opened during a subsequent downshift. Then, the fuel cut control is canceled and the fuel supply is restarted. For this reason, the fuel cut control is turned on and off in a relatively short time, and there is a problem that a shock is generated due to a change in engine output accompanying the fuel cut control. In particular, when a predetermined engine braking force can be obtained when the throttle valve is almost fully closed, and the throttle valve is slightly opened and closed without downshifting to perform engine brake control, the throttle valve opening degree may be reduced. ON, O of fuel cut control due to slight fluctuation etc.
When the FF is repeated, a hunting shock of torque is generated, and the driver may feel uncomfortable.

The present invention has been made in view of the above circumstances, and an object of the present invention is to turn on / off the fuel cut control in the automatic control of the engine braking force in which the fuel cut control is performed in parallel. An object of the present invention is to prevent a shock from occurring.

[0007]

In order to achieve the above object, it is only necessary to prevent the fuel cut control from being performed during the automatic control of the engine braking force. As shown, a fuel that includes an automatic transmission having a plurality of shift speeds, and that shuts off fuel supply to an engine when a predetermined fuel cut condition including at least that a throttle valve is substantially fully closed is satisfied. In a vehicle having cut control means, the accelerator is substantially off
An engine braking force automatic control device that automatically increases the engine braking force so that a predetermined traveling state is established when the vehicle speed increases even in the state,
(A) shift control means for downshifting the automatic transmission to a low gear where engine braking is applied when the throttle valve is substantially fully closed; and (b) during the shift of the downshift by the shift control means. It is characterized by having throttle control means for opening and controlling a throttle valve, and (c) fuel cut restriction means for restricting cutoff of fuel supply by the fuel cut control means during automatic control of engine braking force.

[0008]

In such an automatic engine braking force control apparatus, when the automatic transmission is downshifted by the shift control means to increase the engine braking force, the throttle control means opens the throttle valve. As a result, the shift time required for the downshift is shortened, the life of the friction engagement device of the automatic transmission is extended, and the shift caused by the temporary increase in the engine braking force due to the inertia torque of the engine or the like. Shock is suppressed. In addition, the throttle opening control at the time of the downshift reduces shock caused by a large increase in engine braking force based on a difference in gear ratio, thereby improving ride comfort, and gradually reducing the throttle valve opening after the downshift. By performing the control, the engine braking force is gradually increased, so that an appropriate engine braking force for achieving a predetermined traveling state without requiring an accelerator operation can be obtained.

On the other hand, during the automatic control of the engine braking force, the cutoff of the fuel supply by the fuel cut control means is restricted by the fuel cut restriction means, and the fuel cut control is performed even when the throttle valve is almost fully closed. It is not done or hard to do. Thus, ON / OFF of the fuel cut control accompanying the throttle control at the time of the downshift is suppressed, and the torque fluctuation caused by the ON / OFF of the fuel cut control is favorably avoided. In addition, even when the throttle valve is slightly opened and closed to perform engine brake control without downshifting when the throttle valve is substantially fully closed, the hunting shock of torque is suppressed because the fuel cut control is limited. , The ride comfort is improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

Referring to FIG. 2, an air cleaner 14, an air flow meter 16, an intake passage 18, a throttle valve 20, a bypass passage 22, a surge tank 24, an intake manifold 26,
And air is sucked in through the intake valve 28,
A fuel gas injected from a fuel injection valve 30 provided in the intake manifold 26 is mixed with the air. The air flow meter 16 measures the amount of intake air, and outputs a signal indicating the amount of intake air to the computer 32 for engine control. Throttle valve 20
Is for continuously changing the amount of air taken into the engine 10. The throttle valve opening .theta. Is controlled in accordance with a throttle control signal DTA supplied from a throttle control computer 35. The valve 20 is provided with a throttle position sensor 36, which outputs a throttle valve opening signal Sθ representing the throttle valve opening θ to the engine control computer 32, the transmission control computer 34, and the throttle control computer 35. The throttle position sensor 36 has an idle switch function, and outputs an idle signal indicating that the throttle valve 20 is substantially fully closed to the computers 32, 34, and 35 together with the throttle valve opening signal Sθ. Bypass passage 2
2 is disposed in parallel with the throttle valve 20 and has an idle speed control valve 3
8 and an engine control computer 32
The opening degree of the idle speed control valve 38 is controlled by the control, whereby the amount of air flowing bypassing the throttle valve 20 is adjusted, and the engine speed during idling is controlled. The injection timing and injection amount of the fuel injection valve 30 are also controlled by the engine control computer 32. An intake air temperature sensor 40 for measuring the temperature of the intake air is provided upstream of the air flow meter 16, and a signal representing the intake air temperature is sent to an engine control computer 32.
Output to

The engine 10 includes an intake valve 28 and an exhaust valve 4
2, a piston 44, and a spark plug 46. The spark plug 46 generates an ignition spark by a high voltage supplied from an igniter 48 controlled by an engine control computer 32 via a distributor 50. The crankshaft is rotated by causing the mixed gas in the combustion chamber 12 to explode and move the piston 44 up and down. The intake valve 28 and the exhaust valve 42 are opened and closed by a cam shaft that is driven to rotate in synchronization with the rotation of the crankshaft, and is controlled by a variable valve timing mechanism (not shown) controlled by the engine control computer 32. The opening and closing timing is adjusted by changing the rotational phase of the camshaft and the crankshaft. The exhaust gas burned in the combustion chamber 12 is supplied from the exhaust valve 42 to the exhaust manifold 5.
4. The gas is discharged to the atmosphere via the exhaust passage 56 and the catalyst device 58. The engine 10 is provided with a water temperature sensor 60 for measuring the engine cooling water temperature, and the engine cooling water temperature T
A signal STHW representing HW is output to the engine control computer 32, and the exhaust manifold 54 is provided with an oxygen sensor 62 for detecting the concentration of oxygen in the exhaust gas. Is output to the engine control computer 32. The distributor 50 is provided with a rotation angle sensor 51 that generates a pulse in synchronization with the rotation of the crankshaft. Output to the transmission control computer 34.

Each of the engine control computer 32, transmission control computer 34, and throttle control computer 35 has a CPU, RAM,
The transmission control computer 34 includes an OM, an input / output interface circuit, an A / D converter, etc., and performs signal processing according to a program stored in the ROM while utilizing a temporary storage function of the RAM. Are the above signals, the pattern signal SP representing the selected pattern from the pattern select switch 70, the brake signal SB representing that the brake has been depressed from the brake lamp switch 72, and the overdrive switch 74 to the O / D gear. O / indicating the shift permission of
A D signal SO and an accelerator operation amount signal SAc representing the operation amount Ac of the accelerator pedal are supplied from the accelerator operation amount sensor 76, respectively. The accelerator operation amount signal SAc is also supplied to the computer 32 for engine control and the computer 35 for throttle control. The pattern select switch 70 has at least an automatic engine brake pattern for automatically increasing the engine brake on a downhill or the like, a power pattern for controlling the shift of the automatic transmission 78 by a shift map emphasizing the power performance, and a fuel efficiency. The driver selects and operates a favorite traveling pattern from a plurality of predetermined traveling patterns, such as an economy pattern in which gear shifting control is performed according to an emphasized shift map. The brake lamp switch 72 is provided near the brake pedal, and is turned on and off depending on whether or not the brake pedal is depressed.
It is configured by an ON-OFF switch or the like that switches F.

The automatic transmission 78 includes a torque converter 110, a first transmission 112, and a second transmission 114, for example, as shown in FIG. The pump wheel of the torque converter 110 is connected to the crankshaft 118 of the engine 10, and the turbine wheel is connected to the input shaft 1.
20 is connected to the carrier 122 of the first transmission 112. The first transmission 112 includes a planetary gear unit including a sun gear 124, a ring gear 126, and a planetary gear 128 rotatably disposed on the carrier 122 and meshing with the sun gear 124 and the ring gear 126. 124 and carrier 1
22 and the clutch C ₀ and the one-way clutch F ₀
Are provided in parallel, the sun gear 124 and the housing 130
Brake B ₀ is provided between the.

The second transmission 114 is rotatably disposed on the sun gear 132, the pair of ring gears 134, 136, and the carrier 138, and is rotatable on the planetary gear 140 meshed with the sun gear 132, the ring gear 134, and the carrier 142. The planetary gear 1 disposed and engaged with the sun gear 132 and the ring gear 136
44, a clutch C ₁ is provided between the ring gear 136 and the ring gear 126 of the first transmission 112, and a clutch C ₁ is provided between the sun gear 132 and the ring gear 126. Has a clutch C
₂ is provided between the brake B ₁ represents between the sun gear 132 and the housing 130, and a one-way clutch F ₁ and the brake B ₂ which are disposed in series are provided in parallel, the carrier 138 and the housing 130 brake B ₃ and the one-way clutch F ₂ is provided in parallel to the. The ring gear 134 and the carrier 142 are connected to the output shaft 1.
The output shaft 146 is connected to drive wheels via a differential gear device or the like.

[0016] The clutch C ₀ -C ₂ and the brake B
_{0 to} B ₃ (hereinafter, unless otherwise specified, the clutch C,
The brake B) is a hydraulic friction engagement device that is controlled to be engaged by a hydraulic actuator such as a multi-plate clutch or a band brake so that hydraulic oil is supplied from a hydraulic control circuit 150 to the hydraulic actuator. Has become. The hydraulic control circuit 150 is provided with a number of switching valves and the like, and the solenoids S1, S2, and S3 are switched between energized and de-energized in accordance with signals from the transmission control computer 34, thereby switching the hydraulic circuit. The engagement of the clutch C and the brake B is selectively controlled, and one of the four forward speeds is established, as shown in FIG. In FIG. 4, the mark “○” in the column of solenoid means excitation, and the mark “○” in the column of clutch and brake means engagement. "D", "S",
"L" is the operating range of the shift lever in the driver's seat,
In the “D (drive)” range, the shift control is performed in four steps from 1st to O / D. In the “S (second)” range, the shift control is performed in two steps, 1st and 2nd.
In the (low) range, the gear is fixed to the first shift speed. The gear ratio (the rotation speed of the input shaft 120 / the rotation speed of the output shaft 146) is the largest at 1st, 2nd, 3rd, and O / D.
And the speed ratio of 3rd is 1.0. In the “D” range, the engine brake operates at 3rd and O / D, and does not operate at 1st and 2nd due to the operation of the one-way clutches F ₂ and F ₁ . 1st),
In (2nd), when the solenoid S3 is excited, the brakes B ₃ and B ₁ are engaged, and the engine brake operates. 2n of "S" range
The engine brake is applied even in the first and d ranges. Although illustration is omitted,
When the shift lever is operated to the “R (reverse)” range, the manual shift valve of the hydraulic control circuit 150 is switched to establish the reverse gear.

The automatic transmission 78 is provided with a pair of rotation speed sensors 80 and 82. The rotation speed sensor 80 has an input shaft 120, that is, the torque converter 11
Detects the rotational speed N _T of the turbine impeller of 0, the rotational speed sensor 82 is for detecting the rotational speed N _O of the output shaft 146, the rotational speed N _T, respectively, the rotational speed signal representing the N _O It outputs SN _T and SN _O to the transmission control computer 34. Further, a neutral start switch 84 is provided in the hydraulic control circuit 150, and the "D", "S",
A shift range such as "L" or "R" is detected, and a shift range signal SR representing the shift range is output to the transmission control computer 34. The hydraulic control circuit 150 is also provided with an oil temperature sensor 86 for detecting the oil temperature (A / T oil temperature) THO of the working oil, and the A / T oil temperature T
An oil temperature signal STHO representing HO is output to the transmission control computer 34.

The control computers 32, 3
Necessary information is exchanged between 4 and 35. The throttle valve opening signal Sθ, the engine rotation speed signal SNE, and the accelerator operation amount signal SAc are at least one of the control computers 32, 34, Or, it may be supplied to 35. Further, various other signals indicating the driving state of the vehicle, such as the steering angle of the steering wheel, the gradient of the road surface, the exhaust temperature, etc., may be taken in and used for engine control, shift control of the automatic transmission 78, and throttle control. It is possible.

The engine control computer 32 calculates the intake air amount, throttle valve opening θ, engine speed NE, cooling water temperature THW of the engine 10, intake air temperature, oxygen concentration in the exhaust passage 56, accelerator In accordance with the manipulated variable Ac or the like, for example, the fuel injection by the fuel injection valve 30 is performed based on a predetermined data map or an arithmetic expression to reduce fuel consumption and harmful exhaust gas while securing necessary engine output. Injection amount and injection timing, ignition timing by igniter 48, idle speed control valve 3
8 controls the opening / closing timing of the intake / exhaust valves 28 and 42 by the variable valve timing mechanism. Transmission control computer 34
Are the throttle valve opening θ, the engine speed NE, the selection pattern represented by the pattern signal SP, the presence or absence of a brake operation represented by the brake signal SB, and the O / D represented by the O / D signal SO.
Whether shift to the gear position, an accelerator operation amount Ac, and the like based on the output shaft rotation speed N _O of the automatic transmission 78, the automatic transmission 78 by switching the solenoid S1, S2, and excitation of S3, de-energized, respectively Is controlled to switch the gear position. The transmission control computer 34 also switches between a completely engaged state, a slipped state, and a released state by duty-controlling a solenoid (not shown) provided in the hydraulic control circuit 150 also for the lock-up clutch of the torque converter 110. The throttle valve opening θ of the throttle valve 20 is controlled in accordance with the accelerator operation amount Ac, or the throttle valve opening θ is adjusted when the accelerator operation amount Ac is zero to control the engine braking force. For this purpose, a throttle command signal SQ is output to the throttle control computer 35. Throttle control computer 35
Is basically a throttle control signal D for controlling the throttle valve opening θ in accordance with the throttle command signal SQ.
It outputs TA.

The shift control and the throttle control by the transmission control computer 34 will be specifically described below with reference to the flowcharts of FIGS. The flowcharts of FIGS. 5 and 6 relate to shift control for switching the gear position of the automatic transmission 78, and the flowcharts of FIGS. 7 to 9 relate to throttle control. The following control is performed when the "D (drive)" range in which the gear is shifted in four forward speeds is selected, and is repeatedly executed with a cycle time of about 8 to 32 msec.

Step S1 and subsequent steps in FIG.
In the step of determining whether or not to shift to the eighth gear, step S40 is NO, that is, the flag F3
Is executed when is not “1”. The flag F3 is set in FIG.
Is set to "1" in step SS14 or SS19 in FIG. 8 when all of the conditions of steps SS1 to SS5 are satisfied and any one of the conditions of steps SS1 to SS5 is satisfied. If not, it is set to "0" in step SS6,
Step S1 and subsequent steps are executed in the case of normal shift control in which automatic engine brake control is not performed.

In step S1, it is determined based on the O / D signal SO whether or not a shift up to the O / D gear is possible, and the O / D signal SO is turned off, that is, the O / D gear is prohibited. If there is, the current O /
It is determined whether or not the gear is the D gear. The current gear position is determined based on the output state of the excitation signal for exciting the solenoids S1, S2, and S3. Where O
The / D shift stage means that the overdrive switch 74 has been turned off during traveling at the O / D shift stage. In this case, the flag F2 is set at step S14.
Is set to "1", "3rd" is set as the next gear in step S15. If the determination in step S1 is NO, that is, if the O / D gear is permitted, or if the determination in step S1 is YES, the current gear is not the O / D gear and the determination in step S2 is NO and the current 3rd
Otherwise, if the determination in step S3 is NO, step S4 is subsequently executed. In step S4, it is determined whether or not the current shift speed is the O / D shift speed. If not, the process proceeds to step S5 to determine whether or not to perform an upshift. .

In step S5, a predetermined upshift map is searched to determine an upshift vehicle speed Vu. The upshift map is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, as indicated by the solid line in FIG. 10. As the accelerator operation amount Ac decreases, the vehicle speed V increases. It is designed to upshift to the high speed stage. Upshift vehicle speed Vu
It is determined according to the upshift map based on the accelerator operation amount Ac, at the next step S6, the current vehicle speed V and the shift-up vehicle speed Vu that corresponds to the output shaft rotational speed N _O of the rotational speed signal SN _O represents And compare
It is determined whether to perform an upshift. That is, V ≦
If it is Vu, it is not necessary to perform an upshift, and it is determined in step S8 whether or not the current gear is 1st. However, if V> Vu, the flag F1 is set to "1" in step S7, and then, in step S15, a shift speed higher than the current shift speed is set as the next shift speed. In this case, even if the current gear position is, for example, 2nd, the accelerator operation amount Ac rapidly decreases before the gear position is switched to 3rd after the gearshift to 3rd is determined. If it exceeds the “3 → O / D” upshift line, the O / D shift speed is set. In step S5, the upshift vehicle speeds Vu for all the upshift lines are obtained from the current accelerator operation amount Ac. In step S6, the respective upshift vehicle speeds Vu and the current vehicle speed V are compared to determine the upshift speed change. Do it.

If the determination in step S3 is YES,
If the determination in step S4 is YES, or
If the determination in step 8 is NO, step S10 and subsequent steps are executed to determine whether to perform downshifting. Step S
At 10, a predetermined downshift map is searched to determine a downshift vehicle speed Vd. The downshift map is determined in advance for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, as indicated by the broken line in FIG. 10. As the accelerator operation amount Ac increases, the vehicle speed V decreases. The gear shifts down to the lower gear. The shift-down vehicle speed Vd is determined by the accelerator operation amount A
determined according to downshift map based on the c, at the next step S11, it compares the current vehicle speed V and the downshift vehicle speed Vd corresponding to the output shaft rotational speed N _O, determines whether to perform a downshift I do. That is,
If V> Vd, there is no need to perform a downshift, and the flag F2 is set to “0” in step S13 to end a series of shift determinations.
After setting the flag F2 to "1" in step 12,
In step 15, a shift speed lower than the current shift speed is set as the next shift speed. In this case, even if the current gear position is, for example, O / D, the accelerator operation amount Ac sharply increases after the gear shift determination to 3rd is made and before the gear shift to 3rd is actually performed. "2 ← 3"
When the vehicle goes beyond the downshift line, the second gear is set. In step S10, the current accelerator operation amount Ac
Downshift vehicle speed V for all downshift lines from
In step S11, the respective downshift vehicle speeds Vd are compared with the current vehicle speed V to determine the downshift speed.

If step S40 is YES, that is, if the automatic engine brake control is being executed, step S41 is executed following step S40.
It is determined whether the flag F5 is "0". The flag F5 is
If the automatic engine brake control is executed with all the conditions of steps SS1 to SS5 in FIG. 7 satisfied and the brake is depressed, it is set to “1” in step SS23 in FIG. The flag F is set to "0" in step SS6 or SS12,
If 5 = 0, step S42 is executed and the flag F5
If = 1, step S45 is executed. In step S45 executed when the brake is depressed, a predetermined downshift map during engine braking is searched to determine a downshift vehicle speed Ved during engine braking. The downshift map at the time of engine braking is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, similarly to the normal downshift map shown by the broken line in FIG. ,
It is shifted to a higher vehicle speed side than a normal downshift map, and it is easy to downshift. Shift down vehicle speed Ve
d is compared, determined according to downshift map at the time of engine braking based on the accelerator operation amount Ac, at the next step S46, the current corresponding to the output shaft rotation speed N _O of the vehicle speed V and the downshift vehicle speed Ved Then, it is determined whether to perform a downshift. That is,
If V> Ved, there is no need to perform a downshift, and the flag F2 is set to “0” in step S44 to end the shift determination. If V ≦ Ved, step S4
After setting the flag F2 to "1" in step 7, the process proceeds to step S4
In step 8, a shift speed lower than the current shift speed is set as the next shift speed. The gear set here is the one where the engine brake acts, and in the second or first gear, the gear shown in parentheses in FIG. 4 is set. In this case, even if the current gear is, for example, O / D, the vehicle speed V sharply decreases after the shift to 3rd is determined and before the gear is actually switched to 3rd. When exceeding the “2 ← 3” downshift line, the second shift speed is set. In step S45, the downshift vehicle speeds Ved for all the downshift lines are obtained from the current accelerator operation amount Ac. In step S46, the respective downshift vehicle speeds Ved are compared with the current vehicle speed V to determine the downshift speed change. Do it.

In step S42 executed when the brake is not depressed, it is determined whether or not a flag F4 is "1". The flag F4 is set to "1" in step R11 of FIG. 9 when downshifting is performed to increase the engine braking force in the automatic engine brake control, and when the shift output of the downshift is performed, the flag F4 in FIG. It is set to "0" in step S31, and F4 = 0
If so, the flag F2 is set to "0" in step S44 to end the shift determination, and if F4 = 1, step S4
Execute 3. In step S43, the next low gear at which the engine brake acts as the next gear, that is, 2nd
Alternatively, in the case of 1st, the shift speed shown in parentheses in FIG. 4 is set.

When the next gear is set in step S15, S43 or S48, the gear shift timing time T1 is set in step S16.
The shift timing time T1 is a delay time from when the shift is determined to when the shift output is performed to actually switch the shift stage (step S30), and a plurality of shifts are performed in a short time (multi-shift). ), And even if an upshift to the O / D shift stage is made when the accelerator pedal is quickly released to apply the engine brake on a downhill, before the upshift is actually performed. When the accelerator operation amount Ac becomes substantially zero, it is provided to prohibit an upshift to the O / D shift speed.
A fixed value may be set in advance, but different times may be set according to the type of shift such as upshift, downshift, or downshift in automatic engine brake control. Further, it may be set by a map, an arithmetic expression, or the like according to the accelerator operation amount Ac at the time of the shift determination, the vehicle speed V, the shift speed, and the like.

Next, the flow chart of FIG. 6 for actually changing the gear position will be described. FIG. 6 shows a portion for executing an upshift and a downshift for increasing the engine braking force in accordance with the shift determination of FIG. 5. In step S20, it is determined whether or not the flag F1 is "1", that is, the upshift shift determination is performed. Is determined. If the flag F1 is "1", the steps from step S21 are executed, but if not, the step S33 is executed. In step S33, it is determined whether or not the flag F4 is "1", that is, whether or not the downshift is performed to increase the engine braking force. If the flag F4 is "1", the steps from step S21 are executed. Otherwise, step S32 is immediately executed, the timer Ta is reset, and the process ends.

In step S21, the shift range signal SR
Is determined to be "D (drive)", and in step S22, the traveling pattern represented by the pattern signal SP is determined to be "automatic engine braking pattern".
Determining whether a determines whether larger than the lower limit vehicle speed V1 of the vehicle speed V is preset to correspond to the output shaft rotation speed N _O representing the rotational speed signal SN _O In step S23, in step S24 It is determined whether or not the vehicle speed V is equal to or lower than a predetermined upper limit vehicle speed V2. In step S25, the accelerator is turned off, that is, the accelerator operation amount Ac indicated by the accelerator operation amount signal SAc is substantially zero, specifically, a detection error. In consideration of the above, it is determined whether or not the speed is about 1.5% or less. In step S26, it is determined whether or not the next gear set in step S15 is the O / D gear. The lower limit vehicle speed V
1 and the upper limit vehicle speed V2 define a vehicle speed range in which special control for engine braking is performed, and the lower limit vehicle speed V1
Is set to, for example, about 20 km / h, and the upper limit vehicle speed V2 is set to, for example, about 110 km / h. If any one of the above steps S21 to S26 is NO, in step S28 the change of the next gear set in step S15 is not changed in step S27, but the determination in steps S21 to S26 is made. If all are YES, in step S27, the next gear is set to "3r
d ”. Step S26 determines whether the next gear set in step S15 is O / D. In step S27, the next gear shifts from O / D by 3r.
Even in the cycle after the change to d, the determination in step S26 is YES.

In step S29, it is determined whether or not the time counted by the timer Ta is equal to or longer than the shift timing time T1. Step S20 and subsequent steps are repeated until the shift timing time T1 is reached, but when the shift timing time T1 is reached, step S30 is executed, and the solenoids S1 and S1 are executed.
By switching between excitation and non-excitation of S2 and S3, the gear position of the automatic transmission 78 is switched to the next gear position set in step S15 or S43 or the 3rd gear position changed in step S27. After that, the flag F1 is set to "0" in step S31, the flag F4 is set to "0", and the timer Ta is reset in step S32. This timer Ta determines whether the upshift has been made and the flag F1 has been set to "1" or the downshift has been made to increase the engine braking force and the flag F4 has been set to "1". It measures time.

Here, in step S6, O / D
Even if an upshift to the gear position is determined, step S
Until the gear is actually switched at 30,
That is, the shift timing time T after the shift is determined.
If all of the conditions of steps S21 to S26 including the accelerator OFF are satisfied before the time 1 has elapsed, the next shift speed is changed to 3rd. When the driver releases the accelerator, the actual shift to the O / D shift stage is prevented even if an upshift shift decision is made with a decrease in the accelerator operation amount Ac, and the O / D shift stage is prevented. The reduction of the engine braking force due to the shift to へ is satisfactorily avoided. For example, when the driver releases the accelerator in the state of point A in FIG.
Since the accelerator operation amount Ac crosses the “→ 3” upshift line and the “3 → O / D” upshift line, the shift is finally determined from 2nd to O / D in step S6 in step S6. In step S15, the O / D shift speed is set as the next shift speed. However, if the accelerator operation amount Ac becomes zero before the shift timing time T1 elapses after the “2 → 3” upshift is determined, "3 → O /
Even if the next gear shifts to O / D after crossing the "D" upshift line, the next gear is changed to 3rd in step S27, so that the gear is not upshifted to the O / D gear.

Even if the accelerator is turned off once,
If the depressing operation is performed again before the shift timing time T1 is reached, the determination in step S25 is NO, and the next shift speed is set to the O / D set in step S15 in step S28. When the vehicle is depressed, since the driver does not need so much engine braking force, the driver may upshift to the O / D gear position. The determination in step S29 is inserted between steps S20 and S21, and the determination in step S21 and subsequent steps are executed based on the driving state after the shift timing time T1 has elapsed, so that the shift speed is switched. good.

Also, the speed of returning the accelerator is relatively slow,
Even when the accelerator is not turned off within the shift timing time T1, the shift is performed as set in step S15, but also in this case, since the driver does not need so much engine braking force, the O / There is no problem in upshifting to the D gear. In other words,
When the driver needs the engine braking force, the accelerator pedal may be quickly released, and when the driver desires coasting or the like that does not require much engine braking force, the accelerator pedal may be released slowly. It is good.

Next, the throttle control in FIGS. 7 to 9 will be described. First, in steps SS1 to SS5 in FIG. When the judgment is made and all the conditions are satisfied, the automatic engine brake control in step SS8 and thereafter is executed.
If any one is NO, step SS6 in FIG.
, The flag F3, the flag F5, and the flag F7 are each set to “0”, and normal throttle control is performed in step SS7. In the normal throttle control in step SS7, the throttle valve opening TA (Ac) is obtained from a predetermined map or an arithmetic expression based on the accelerator operation amount Ac indicated by the accelerator operation amount signal SAc, and the throttle valve opening TA (Ac) is the target throttle valve opening TA
^{* And} the target throttle valve opening TA
A throttle command signal SQ indicating ^* is output to the throttle control computer 35. The throttle control computer 35 controls the throttle valve 20 so that the actual throttle valve opening θ of the throttle valve 20 matches the target throttle valve opening TA ^* indicated by the throttle command signal SQ, that is, TA (Ac) by feedback control or the like. The control signal DTA is output to the throttle valve 20.

In step SS8, which is executed when all the conditions in steps SS1 to SS5 are satisfied, the flag F
It is determined whether or not 3 is “1”.
Is set to “0” in step SS6, and is “0” when step SS8 is first executed,
Subsequently, step SS10 is executed, and the vehicle speed V at that time is set to the target vehicle speed Vm. Since the flag F3 is set to “1” in step SS14 or SS19 in FIG. 8,
In the subsequent cycles, the determination in step SS8 is YES, and step SS9 is executed. In step SS9,
The vehicle speed (Vm-Vf) obtained by subtracting a predetermined constant value Vf from the target vehicle speed Vm is compared with the vehicle speed V at that time.
If (Vm-Vf), step SS11 and subsequent steps in FIG. 8 are executed, but if V ≦ (Vm-Vf), step SS10 is executed again, and the target vehicle speed Vm is changed to the current vehicle speed V. Execute SS11 and below. The constant value Vf is determined by considering the change in the vehicle speed V due to the feedback control of the throttle valve opening θ in steps R4 and R6 in FIG. However, if the vehicle speed V is relatively greatly reduced by the brake depressing operation, the determination in step SS9 is NO, and the target vehicle speed Vm is changed in step SS10.

In step SS11 of FIG. 8, it is determined whether or not the brake is depressed based on the brake signal SB. If the brake is off, that is, if the brake is not depressed, steps SS12 and subsequent steps are executed. If the user steps on the brake to further decelerate, the determination in step SS11 is NO, and steps SS22 and SS23 are executed. Step SS2
In step 2, the target throttle valve opening TA ^{* is set} to 0 in order to increase the engine braking force, and a throttle command signal SQ indicating the target throttle valve opening TA ^* is output to the throttle control computer 35, whereby the throttle valve is opened. 20 is fully closed. Further, in step SS23, the flag F5 is set to "1", so that steps S45 and subsequent steps in FIG. 5 are executed. At the beginning of the automatic engine brake control, that is, in the first cycle in which the accelerator is turned off, the normal brake is turned off.
The determination of step 1 is YES, and step SS14 or SS
At step 19, the flag F3 is set to "1", and in FIG. 5, each step of the engine braking after step S41 is executed.

Step SS executed when brake is off
In step 12, the flag F5 is set to "0", and in step SS13, it is determined whether or not the flag F1 is "1".
At 6, it is determined whether or not an upshift has been determined. If the flag F1 = 1, the flag F3 is set to "1" in step SS14, and then in step SS15, the same normal throttle control as in step SS7 is performed. When the upshift shift determination is not made, or when the upshift shift output is made and the flag F1 is set to “0” in step S31 of FIG. 6, the determination in step SS13 is NO. In step SS16, it is determined whether the flag F6 is "0". The flag F6 is set to “1” in step R11 in FIG. 9 when downshifting is performed to increase the engine braking force. When the flag F6 = 0,
In step SS17, it is determined whether or not the flag F3 is already "1".

If the flag F3 is not "1" in the first cycle of the automatic engine brake control and the determination in step SS17 is NO, the flag F3 is set to "1" in step SS19, and then step SS20 is executed. The same normal throttle control as in step SS7 is performed.
When the flag F3 = 1, it is determined in step SS18 whether or not the gear is being shifted, for example, by whether or not the following equation (1) is satisfied. That is, the gear shift output is made in step S30 of FIG.
2, S3 excitation and de-energized is switched began slippage in the clutch C and brake B of the automatic transmission 78, after the rotation speed ratio of the turbine speed N _T and the output shaft rotation speed N _O is shifting, i.e. for shifting by substantially coincides with the gear ratio i of the current speed after the shift output ends, the rotational speed N _T of it such as, N _O, and the speed ratio i of the current gear stage
Is not shifting when the following formula (1) is satisfied, and is shifting when the following formula (1) is not satisfied. Then, if the determination in step SS18 is YES, that is, if the shift is not being performed, the automatic engine brake throttle processing routine of step SS21 is executed. If the shift is being performed, step SS20 is executed. The above equation (1), the rotational speed N _T, taking into account the detection error of N _O are determined so as to satisfy with a predetermined width. Also, during a downshift to increase the engine braking force,
Since step SS24 and subsequent steps are executed subsequent to step SS16, it is determined in step SS18 whether or not the shift is substantially during the upshift.

[0039]

N _T ＮN _O × i (1)

In the automatic engine brake throttle processing routine of step SS21, the vehicle speed V is substantially equal to the target vehicle speed Vm in this embodiment so that the actual vehicle speed V does not exceed the target vehicle speed Vm set in step SS10 of FIG. The feedback control of the throttle valve opening θ is performed so as to coincide with each other, and is specifically executed according to the flowchart of FIG. In step R1 of FIG. 9, it is determined whether the throttle valve opening θ is smaller than a predetermined determination value θ1. The determination value θ1 is a small value of about 1.5% or less, and is determined based on an idle signal indicating that the throttle valve 20 is substantially fully closed. If θ ≧ θ1, that is, if the engine braking force can be increased by closing the throttle valve 20, the timer Tc is reset in step R2 and the step R3 is performed.
After setting the flag F7 to 1, the step R4 is executed.
In step R4, the target vehicle speed Vm and the current vehicle speed V
The throttle valve opening TA1 (%) for making the vehicle speed V substantially equal to the target vehicle speed Vm is calculated in accordance with the arithmetic expression of the feedback control.

In the next step R5, based on the current gear position and the target vehicle speed Vm, the throttle valve opening capable of maintaining the target vehicle speed Vm when traveling on flat ground, that is, the driving force in consideration of the running resistance becomes zero. Throttle valve opening TAm
(%) Is calculated by map interpolation from a data map stored in advance as shown in FIG. 11, for example, and it is determined whether or not the throttle valve opening TA1 is smaller than the throttle valve opening TAm. The data map shown in FIG. 11 is obtained by calculating the throttle valve opening at which the driving force matches the running resistance for each gear position and vehicle speed based on the data as shown in FIG. 12 obtained experimentally in advance. . FIG.
Data indicates that the shift speed of the automatic transmission 78 is O / D in a vehicle equipped with an engine having the output characteristics shown in FIG.
(Total gear ratio = 2.8905), the gear transmission efficiency is 0.855, and the tire effective radius is 0.306 m. For example, when the vehicle speed is 80 km / h, the throttle valve opening TAm (%) is flat. Since the throttle valve opening (angle) at point B, which coincides with the running resistance on the ground, is about 7.4 °, when this is converted to% with respect to 80 ° of full opening,
(7.4 / 80) × 100 = 9.3. That is,
In the data map of FIG. 11, the vehicle speed 8
The throttle valve opening TA _{45 at} 0 km / h is specifically 9.3%. Thus, the throttle valve openings TA _{41 to} TA _{47 at} each vehicle speed in the O / D shift stage are obtained. ing. Regarding the 3rd gear and the 2nd gear and the 1st gear where the engine brake operates, the above O /
The throttle valve opening TA ₃₁ to
_{TA 37, TA 21 ~TA 27,} TA 11 ~TA 17 is required. As is clear from the data in FIG. 12, the throttle valve opening TAm increases as the vehicle speed increases, and increases at lower speeds with a higher gear ratio at the same vehicle speed.

If TA1 <TAm, in step R6, the throttle valve opening TA1 is set to the target throttle valve opening TA ^* , and the target throttle valve opening T ^* is set.
By outputting a throttle command signal SQ representing A ^* to the throttle control computer 35, the actual throttle valve opening θ of the throttle valve 20 becomes equal to the throttle valve opening T.
A1 is controlled. These steps R4, R
5 and R6 are repeatedly executed, so that the throttle valve opening θ is quickly controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, and the target vehicle speed Vm when the accelerator is off or the vehicle speed V due to the brake depression operation is reduced. As a result, the engine braking force at which the vehicle travels at the target vehicle speed Vm that has been changed is obtained. In this embodiment, the vehicle speed V is set to the target vehicle speed Vm.
The throttle valve opening θ is feedback-controlled so as to substantially match the vehicle speed V regardless of the change in the road surface gradient.
The engine braking force is increased or decreased so as to substantially match the target vehicle speed Vm, and when the gradient changes from a steep gradient to a gentle gradient, the vehicle speed V is prevented from being reduced against the driver's intention due to excessive application of the engine brake. You.

On the other hand, if TA1 ≧ TAm, the determination in step R5 is NO, and in step R7, the throttle valve opening TAm is set to the target throttle valve opening TA ^* , and the target throttle valve opening TA ^* is expressed. By outputting the throttle command signal SQ to the throttle control computer 35, the throttle valve 20 is controlled so that the actual throttle valve opening θ becomes the throttle valve opening TAm. This is because the engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm irrespective of the change in the road surface gradient as described above. Is opened and the vehicle speed V is maintained at the target vehicle speed Vm. However, in such an engine brake control, it is normal that the driver thinks that the vehicle speed V decreases on an uphill, and when driving on a flat ground. If so, the throttle valve opening TAm that can maintain the target vehicle speed Vm is set as the upper limit of the throttle valve opening TA1 by feedback control. As a result, the target vehicle speed Vm is maintained on a downhill or a flat ground, but on an uphill, the vehicle speed V becomes lower than the target vehicle speed Vm in accordance with the gradient, and the driving control as intended by the driver is performed. Become so.

When the throttle valve 20 is substantially fully closed and the throttle control cannot increase the engine braking force, the determination in step R1 is YES, step R8 is executed, and the flag F7 is set to "1". It is determined whether or not there is. If the flag F7 is not “1”,
That is, when step R8 is executed following step R1 in the first cycle in which the accelerator is turned off, step R2 and subsequent steps are executed to reset the timer Tc and set the flag F7 to "1". In the next step R9, it is determined whether or not the content of the time measured by the timer Tc, that is, whether or not the elapsed time from when the throttle valve 20 is substantially fully closed has exceeded a predetermined delay time T3. In the delay time T3, even if the throttle valve 20 is substantially fully closed, a sufficient engine braking force cannot be obtained, and the aforementioned step R4
This is for determining whether or not the throttle valve 20 is maintained in the fully-closed state by the feedback control by R6. A constant value may be set in advance, but the type of shift and the vehicle speed V are used as parameters. You may make it set by a data map, fuzzy inference, etc. And T
If c <T3, the above steps R3 and subsequent steps are executed.
If Tc ≧ T3, in the following step R10,
It is determined whether or not the current gear is the lowest gear capable of obtaining the engine braking action, that is, in this embodiment, whether or not the solenoid S3 is the first gear in which the solenoid is excited.
In the case of the gear position, the downshift cannot be performed, so that the execution of step R3 and subsequent steps is repeated. If the shift speed is other than 1st, step R11 and the following steps are executed to set a flag F4 for instructing a downshift to increase the engine braking force to "1" and a flag representing throttle control at the time of the downshift. F6 is set to “1”. When the flag F4 is set to "1", the step S43 in FIG. 5 is executed, and when the flag F6 is set to "1", the step S24 in FIG.
The following will be performed:

In the next step R12, the throttle valve opening degree TA2 (%) at which substantially the same driving force can be obtained before and after the downshift is calculated based on the type of downshift and the current vehicle speed V, as shown in FIG. Calculated by map interpolation from a predetermined data map as shown in FIG. The data map shown in FIG. 14 is based on the driving force data shown in FIG.
Is the same as or slightly smaller than the driving force when the valve is fully closed (in this case, acting as a braking force), in other words, the driving force at which the engine braking force is the same or slightly larger even after a downshift. Valve opening degree TA2
(%) Is obtained for each type of shift and vehicle speed. For example, the driving force when the accelerator is off when the vehicle speed is 80 km / h at the O / D gear is about -300 N as shown by the point C in FIG. 12, so that the O / D gear is reduced to the 3rd gear. 3 if shifted
In the data corresponding to FIG. 12 in the case of rd, the vehicle speed is 8
The value of the throttle valve opening at which the driving force at 0 km / h, that is, the driving force equal to or slightly smaller than -300 N is obtained is the throttle valve opening TA2. “O / D → 3r” in FIG.
d ”The throttle valve opening degrees TA2 _{31 to} TA2 _3n at the time of shifting are
Thus it is determined for each vehicle speed V ₁ ~V _n are,
"3rd → 2nd (S3ON)" and the throttle valve opening TA2 ₂₁ ~TA2 _2n during the shift, "2nd → 1st (S3
ON) "Throttle valve opening TA2 _{11 to} TA2 _1n at the time of shifting
Is determined in the same manner as described above using the driving force data of the second shift speed and the first shift speed. The throttle valve opening TA2 increases as the vehicle speed increases for the same type of shift, and for the same vehicle speed, the downshift on the low speed side becomes larger than the downshift on the high speed side.

In the following step R13, a change timing time T2 of the throttle valve opening θ is set. The throttle valve opening change timing time T2 is a delay time from when the downshift transmission is output in step S30 to when the throttle valve 20 is controlled to open, and the high speed side released during the downshift. The current engine speed NE and the A / T oil temperature THO are set in advance by experiments and simulations so that the engine speed NE increases in accordance with the timing at which the clutch C and the brake B begin to slip. It is calculated by map interpolation from the data map of FIG. In this case, the higher the A / T oil temperature THO, the lower the viscous resistance of the hydraulic oil, the shorter the time required for drain and supply, and the higher the speed output, the higher the clutch C and brake B on the high-speed side. Since the delay time before the start of slipping is short, the throttle valve opening change timing time T2 becomes smaller as the A / T oil temperature THO becomes higher. Further, the higher the engine rotational speed NE, the longer the delay time between opening the throttle valve 20 and controlling the opening of the engine 10 and the actual blow-up of the engine 10 becomes longer. It will be a small value.

When the flag F6 is set to "1" in step R11, in the subsequent cycle, step SS in FIG.
The determination at 16 is NO, and step SS24 is executed. In step SS24, it is determined whether or not the gearshift output for downshifting is performed in step S30 and the flag F4 is set to "0" in the next step S31, and the process proceeds to step SS25 until F4 = 0. , The timer Tb is reset, and when F4 = 0, steps SS26 and subsequent steps are executed. By resetting the timer Tb in step SS25, the timer Tb measures the elapsed time from when the flag F4 is set to “0”, in other words, when the downshift transmission output is performed, In step SS26, the timer T
It is determined whether or not the counted time of b is equal to or longer than the throttle valve opening change timing time T2. Then, when the counted content of the timer Tb reaches the change timing time T2,
In step SS27 by setting the throttle valve opening TA2 to the target throttle valve opening degree TA ^*, and outputs a throttle command signal SQ indicating the target throttle valve opening TA ^* to the throttle control computer 35, the throttle valve 20 Control is performed so that the actual throttle valve opening θ becomes the throttle valve opening TA2. Further, in the next step SS28, the speed ratio i of the current speed stage after the downshift speed change output is made, and the rotational speeds _NT , N
Based on _O , it is determined from the above equation (1) whether or not the shift is completed. When the shift is completed, the flag F6 is set to "0" in step SS29. As a result, in the subsequent cycle, step SS17 and subsequent steps are executed following step SS16.

As described above, in this embodiment, when the downshift is performed in the accelerator OFF state in order to increase the engine braking force, the driving force after the downshift is equal to or slightly smaller than the driving force before the downshift. Since the throttle valve 20 is controlled to open to the throttle valve opening degree TA2, substantially the same engine braking force as before the downshift is applied even after the downshift, and the shock caused by the sudden increase in the engine braking force is reduced. Being improved ride comfort. After the downshift, step R
4 or less, the vehicle speed V becomes the target vehicle speed Vm.
Since the throttle valve 20 is feedback-controlled so as to coincide with the above, an appropriate engine braking force can be obtained, and there is no inconvenience that the engine braking force becomes excessive due to the downshift and the accelerator operation is required. Driving operation becomes extremely easy. In this embodiment, the state in which the vehicle travels at the target vehicle speed Vm is a predetermined traveling state.

Further, in this embodiment, the engine speed N is adjusted in accordance with the timing at which the clutch C and the brake B on the high speed stage released by the downshift start slipping.
Since the timing at which the throttle valve 20 is opened and controlled is determined so that E increases, even during a shift process in which the engagement switching of the clutch C and the brake B is performed, a temporary stop due to an inertia torque of the engine 10 or the like. In addition to suppressing the increase in braking force, the engine speed NE is quickly increased in combination with the transmission of torque from the driving wheel side, the shift time is shortened, and the life of the friction materials of the clutch C and the brake B is improved. I do.

FIG. 16 shows a vehicle speed of 55 km / h on an 8% downhill by the automatic engine brake control of this embodiment.
FIG. 9 is a time chart showing a change in rotational speed, a change in driving torque, and the like of each part when a downshift is performed from the third gear to the second gear at the time of the shift, that is, the friction engagement device (clutch C ₂₎ on the high speed side. ) Is about 0.69 sec from when the slip begins to occur until the friction engagement device (brake B ₁ ) on the low-speed side fully engages.

The line oil pressure of the hydraulic control circuit 150 is generally controlled in accordance with the throttle valve opening θ. When the throttle valve 20 is controlled to open as described above, the line oil pressure is increased. Accordingly, the engagement hydraulic pressure of the clutch C and the brake B is also increased, so that the clutch C and the brake B on the low speed side are rapidly and completely engaged, so that the shift time is further shortened. However, in this case, since a large shift shock is likely to occur, in this embodiment, at the time of opening control of the throttle valve 20 in step SS27, the line oil pressure is controlled to a low oil pressure when the throttle valve 20 is fully closed. ing.

In this embodiment, a part of the series of signal processing performed by the transmission control computer 34 for executing steps S30, S42, S43 and R11 corresponds to a shift control means, and steps R4, R6, R12 and R1 are performed.
3, the part executing SS27 constitutes throttle control means together with the throttle control computer 35.

On the other hand, the engine control computer 3
Reference numeral 2 denotes feedback control based on the oxygen concentration in the exhaust gas detected by the oxygen sensor 62 so that the mixture in the combustion chamber 12 has, for example, a stoichiometric air-fuel ratio. However, in order to prevent overheating of the catalyst device 58 and reduce fuel consumption, when a predetermined fuel cut condition is satisfied, the power supply to the fuel injector 30 is cut off to stop the injection of the fuel gas. Has become. Such fuel cut control is executed according to the flowchart of FIG. 17, and is repeated at a cycle time of, for example, about 8 to 32 msec.

In step FC1 of FIG. 17, it is determined whether fuel cut conditions other than the engine speed NE are satisfied. The fuel cut condition includes that at least the throttle valve 20 is substantially fully closed and the idle switch of the throttle position sensor 36 is ON. Is executed to stop the fuel cut control, and the fuel injection from the fuel injection valve 30 is performed. If all the fuel cut conditions other than the engine rotational speed NE are satisfied, step FC2 is executed. In step FC2,
Engine cooling water temperature T detected by water temperature sensor 60
Based on the HW, for example, a determination value NE1 is obtained by map interpolation from a predetermined data map shown in FIG.
And NE2 are calculated. The judgment value NE1 is a value at which the fuel cut control is stopped when the engine speed NE becomes lower, and the judgment value NE2 is a value at which the fuel cut control is started when the engine speed NE becomes higher. And the judgment value NE for providing hysteresis.
2 is a value higher than NE1 by about 400 rpm. Only one of the judgment values NE1 and NE2 may be stored in the data map, and a predetermined value may be added to or subtracted from the value to calculate the other judgment value.

In the next step FC3, it is determined whether or not the automatic engine brake control is currently being executed based on whether or not the flag F3 in the throttle control is "1".
The content of the flag F3 is read from the transmission control computer 34. If the automatic engine brake control is not being executed, the process immediately proceeds to step FC.
5 is executed, but if the automatic engine brake control is being executed, the judgment value NE2 is set in step FC4.
To NE3. NE3 is larger than NE2,
For example, it is a large value that does not substantially exceed the engine rotation speed NE, and may be determined in advance according to the performance of the engine 10 or may be obtained by adding a predetermined value to the determination value NE2. You may do it.

In step FC5, it is determined whether or not the fuel cut control is currently being executed. If the fuel cut control is being executed, in step FC6, it is determined whether or not the current engine speed NE is smaller than the above-mentioned determination value NE1. On the other hand, if the fuel cut control is not being performed, it is determined in step FC7 whether the current engine speed NE is equal to or greater than the determination value NE2. The determination as to whether or not the fuel cut control is being performed in step FC5 can be made using a flag or the like. The determination value NE2 in step FC7 is NE3 when the automatic engine brake control is being performed. If the judgment in step FC6 is YES or the judgment in step FC7 is NO, step FC8
, The fuel cut control is stopped, and fuel injection from the fuel injection valve 30 is performed. If the determination in step FC6 is NO or the determination in step FC7 is YES, the fuel cut control is performed in step FC9 and the fuel injection valve is stopped. 30
Stop fuel injection from.

Here, when the automatic engine brake control is being executed, since NE3 is used as the judgment value NE2, the fuel cut control is performed in a range where the engine speed NE is higher than usual, and the fuel is accordingly reduced. The cutting conditions become severe, and it becomes difficult to perform fuel cut control.
Therefore, during automatic engine brake control by the transmission control computer 34, the throttle valve 20 is substantially fully closed and opened during downshifting, so that the idle switch is temporarily turned on.
Even in such a case, the cutoff of the fuel supply by the fuel cut control is restricted by changing the determination value NE2, and the torque fluctuation due to the ON / OFF of the fuel cut control is less likely to occur. When the vehicle speed V becomes substantially equal to the target vehicle speed Vm when the throttle valve 20 is substantially fully closed, the feedback control in steps R4 and R6 allows the throttle valve 20 to be substantially fully closed. Since the opening and closing control is slightly performed, the idle switch is repeatedly turned ON and OFF in accordance with the opening and closing control. In this case, however, the fuel cut control is difficult to be performed.
Hunting shock of torque due to repetition of N and OFF is unlikely to occur. If NE3 is set to a very large value, the fuel cut control during the execution of the automatic engine brake control is substantially prohibited.

In this embodiment, of the series of signal processing by the engine control computer 32, the part for executing each of the steps FC1 to FC9 in FIG. The part executing steps FC3 and FC4 in the middle corresponds to fuel cut limiting means.

In the above example, the fuel cut control is restricted by changing the judgment value NE2 relating to the engine speed NE. However, the fuel cut start time T4 is changed as shown in FIG. Cut control can also be made difficult. That is, first, in step FD1,
It is determined whether or not a fuel cut condition other than the fuel cut start time T4 is satisfied. If at least one fuel cut condition is not satisfied, the timer Ti is reset in step FD2. The fuel cut conditions include, besides that the idle switch is ON, the engine speed NE is equal to or higher than the judgment value NE2 when the fuel cut control is not being executed, and the engine speed is not being executed when the fuel cut control is being executed. NE may be equal to or greater than the determination value NE1. When all of these fuel cut conditions are satisfied, step FD3 is subsequently executed to determine whether or not the automatic engine brake control is currently being executed based on whether or not the flag F3 is "1". I do. If the automatic engine brake control is being executed, the fuel cut start time T is set at step FD4.
Change 4 to T4 '. The fuel cut start time T4 is set to 0.5 sec in advance to prevent hunting of the fuel cut control.
The value of the degree is set, and the time T4 'is a longer time.

Thereafter, in step FD5, the timer T
i, that is, the determination in step FD1 is N
It is determined whether the elapsed time after changing from O to YES is equal to or longer than the fuel cut start time T4, and the fuel cut control is stopped in step FD6 until the fuel cut start time T4 has elapsed. Cut start time T
After the elapse of 4, fuel cut control is performed in step FD7. The fuel cut start time T4 is the time T4 'during execution of the automatic engine brake control.

As described above, during execution of the automatic engine brake control, T4 'is used as the fuel cut start time T4. Therefore, after the fuel cut conditions regarding the throttle valve opening θ, the engine speed NE, and the like are satisfied, the fuel cut control is performed. The time until the start is increased, the fuel cut conditions become stricter, and it becomes difficult to perform the fuel cut control. Therefore, the transmission control computer 3
4, the throttle valve 20 is almost fully closed and the idle switch is temporarily turned off.
Even if it becomes N, the execution of the fuel cut control is limited, and even when the opening control is performed at the time of the downshift, the torque fluctuation due to the ON / OFF of the fuel cut control hardly occurs. When the throttle valve 20 is almost fully closed, the vehicle speed V becomes substantially equal to the target vehicle speed Vm.
Even when the idle switch is repeatedly turned ON and OFF in a substantially fully closed state and the ON / OFF is repeated, if the ON time is shorter than the time T4 ', the fuel cut control is not performed, and no torque hunting shock occurs. If the time T4 'is set to a very large value, the fuel cut control during the execution of the automatic engine brake control is substantially prohibited.

FIG. 20 is an example of a time chart at the time of a downshift accompanying the full closing of the throttle valve 20.
4 'is a case where the fully closed time Td is longer than the fully closed time Td from when the throttle valve 20 is substantially fully closed to when the throttle valve 20 is opened and controlled in accordance with the downshift by the automatic engine braking force control. Not done. In contrast,
The normal fuel cut start time T4 is shorter than the fully closed time Td, and the fuel cut control is temporarily performed as shown by the dashed line to cause torque fluctuation. Although a fixed value may be set in advance as the time T4 ', the fully closed time Td
Is the timing time T1, T2 and the delay time T
3, it may be calculated from a data map or the like using the engine speed NE or the like as a parameter.

In this embodiment, a part for executing steps FD1 to FD7 in FIG. 19 in a series of signal processing by the engine control computer 32 constitutes a fuel cut control means together with the fuel injection valve 30. The part that executes steps FD3 and FD4 in the middle corresponds to fuel cut limiting means.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above-described embodiment, a vehicle in which the throttle valve opening θ is always controlled by the throttle control computer 35 has been described. The present invention is also applicable to a vehicle that automatically controls opening and closing of the throttle valve 20 in the OFF state. The configuration of the automatic transmission 78 and the number of shift stages can also be changed as appropriate.

In the above-described embodiment, the throttle valve opening TA2 is set based on the type of shift and the vehicle speed V. However, the operating state of the EGR (exhaust gas recirculation device) and the engine coolant temperature THW The engine output changes due to the engine friction torque change due to
Even if the throttle valve opening degree θ is the same due to a change in the oil pump drive torque due to the / T oil temperature THO, a change in the friction torque of the torque converter 110 and the input shaft 120, and a change in the drive torque of auxiliary equipment such as an air conditioner, an alternator, etc. Since the torque required for the rotational blowing of 120 changes, it is also possible to set the throttle valve opening TA2 in consideration of these operating conditions.

The throttle valve opening TA2 is not necessarily limited to a value at which the driving force before and after the gear shift is substantially equal, but may be larger or smaller than that. At the beginning of the shift when the device starts to slip, the crankshaft 118 and the torque converter 110
In consideration of the inertia component of the throttle valve opening T
It is also possible to add a predetermined value ΔTA to A2 to control the opening of the throttle valve 20, or to temporarily open the throttle valve 20 widely until the engine speed increases.

In the above-described embodiment, the throttle valve opening change timing time T2 is determined so that the engine rotational speed NE increases almost at the same time as the friction engagement device on the high speed side released during the downshift starts slipping. However, it is sufficient that the engine output is increased at least from the start of the slip to the time of complete engagement of the friction engagement device on the low speed side.

In the above-described embodiment, the timer Tb measures the elapsed time with the shift output time in step S30 as the measurement start time. As a matter of course, the elapsed time may be measured, and the opening control of the throttle valve 20 may be started by detecting the slippage of the friction engagement device on the high-speed side by using a rotational speed sensor, a hydraulic sensor, or the like. good.

In the above-described embodiment, the automatic engine brake control in step SS8 and subsequent steps is executed on condition that the automatic engine brake pattern is selected by the pattern select switch 70. Automatic engine brake control when the driving pattern is selected,
Automatic engine brake control may be executed regardless of the type of travel pattern. Of course, a switch for engine brake control can be provided independently of the pattern select switch 70.

In the above-described embodiment, the vehicle speed limitation in steps SS3 and SS4 is provided as a condition for performing the automatic engine brake control. However, such vehicle speed limitation is not necessarily essential, and the range of the vehicle speed limitation is appropriately determined. Another condition may be added as a condition for performing the automatic engine brake control.

Further, in the above-described embodiment, every time the determination in step SS9 becomes NO with the decrease in the vehicle speed V, step SS
10, the target vehicle speed Vm is sequentially changed according to the vehicle speed V at that time.
S9 may be omitted, and the target vehicle speed Vm may be changed according to the vehicle speed V when the brake is released, or the target vehicle speed Vm may be sequentially updated based on the vehicle speed V when the brake is turned on.

Further, in the above-described embodiment, step S2 in FIG.
Even if the next gear is changed to 3rd in step 7, if the accelerator is depressed before reaching the gear shift timing time T1, the next gear is returned to O / D in step S28, but the next gear is returned in step S27. Is changed to 3rd, the shift output may be performed by executing step S30 immediately before the shift timing time T1 is reached.

In the above-described embodiment, the vehicle speed V when the accelerator is turned off or the brake is released is set to the target vehicle speed Vm as it is. The target vehicle speed Vm may be set by adding or subtracting a predetermined value to or from the vehicle speed V in consideration of an error or the like.

In the above embodiment, the vehicle speed V is set to the target vehicle speed V.
m, the throttle valve opening θ is feedback controlled so as to be equal to m. However, the throttle valve opening θ may be increased or decreased by a predetermined constant amount ΔTA, or the vehicle speed V
It is also possible to use other control methods such as reducing the throttle valve opening θ by a fixed amount ΔTA so that the vehicle speed does not exceed the target vehicle speed Vm. Step S
The constant value Vf in S9 is determined in consideration of the fluctuation of the vehicle speed V accompanying the control of the throttle valve opening θ. The present invention can be applied to other automatic engine brake controls, such as performing a downshift so that the acceleration becomes negative to increase the engine brake force. The present invention is also applicable to a case where the vehicle speed V is constant even when the accelerator is off. It can also be used for engine brake control on a downhill when performing high-speed running control.

In the above-described embodiment, the fuel cut condition is strict and the fuel cut control is restricted or substantially prohibited. However, the fuel cut control is uniformly performed during the execution of the automatic engine brake control. It may be prohibited. It is possible to limit the fuel cut control by changing both the engine speed NE and the fuel cut condition relating to the fuel cut start time T4, or to limit the fuel cut control by changing the other fuel cut conditions. is there.

Further, in the above-described embodiment, the vehicle for performing the fuel injection control has been described. However, even for the carburetor type vehicle, the fuel cut control can be performed by shutting off the fuel supply path by a solenoid valve or the like.

In the above-described embodiment, the engine control computer 32, the transmission control computer 34, and the throttle control computer 35 are formed separately, but they may be formed by a single computer. It is possible.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a diagram illustrating a configuration of an automatic transmission and an engine portion of a vehicle including an engine braking force control device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of the automatic transmission in FIG. 2;

FIG. 4 is a diagram showing a shift speed of the automatic transmission shown in FIG. 3, an excitation of a solenoid for establishing the shift speed, and an engagement operation of a clutch and a brake.

FIG. 5 is a flowchart illustrating an operation of a shift determination of whether or not to change the gear position of the automatic transmission of FIG. 2;

FIG. 6 is a flowchart illustrating an operation of a shift control for switching a shift speed of the automatic transmission of FIG. 2;

7 is a flowchart illustrating an operation of controlling the throttle valve opening of the engine in FIG. 2 together with FIG. 8;

8 is a flowchart illustrating an operation of controlling the throttle valve opening of the engine in FIG. 2 in conjunction with FIG. 7;

FIG. 9 is a flowchart illustrating the contents of an automatic engine brake throttle processing routine of FIG. 8;

FIG. 10 is an example of a shift map for switching a shift speed of the automatic transmission of FIG. 2;

FIG. 11 is an example of a data map used for obtaining a throttle valve opening TAm in step R5 of FIG. 9;

FIG. 12 shows basic data for creating the data map of FIG.

FIG. 13 is data showing output characteristics of an engine used to obtain the basic data of FIG.

FIG. 14 is an example of a data map used for obtaining a throttle valve opening TA2 in step R12 of FIG. 9;

FIG. 15 is an example of a data map used for obtaining a throttle valve opening change timing T2 in step R13 of FIG. 9;

16 is a diagram showing an example of FIG. 2 from the third gear to 2n.
6 is a time chart showing changes in the rotation speed, drive torque, and the like of each unit when a downshift is performed to a shift stage d.

FIG. 17 is a flowchart illustrating an operation of fuel cut control in the embodiment of FIG. 2;

FIG. 18 is a flowchart showing the judgment values NE1, N in step FC2 of FIG.
It is an example of a data map used when obtaining E2.

FIG. 19 is a flowchart illustrating another example of the fuel cut control in the embodiment of FIG. 2;

FIG. 20 is a time chart for explaining changes in the throttle valve opening, the idle switch, and the fuel cut when the fuel cut control is restricted according to the flowchart of FIG. 19 when the downshift is performed in the automatic engine brake control.

[Explanation of symbols]

10: Engine 20: Throttle valve 30: Fuel injection valve 32: Engine control computer 34: Transmission control computer 35: Throttle control computer 78: Automatic transmission Step S30, S42, S43, R11: Transmission control means Step R4 R6, R12, R13, SS27: throttle control means Step FC1 to FC9: fuel cut control means Step FC3, FC4: fuel cut limit means Step FD1 to FD7: fuel cut control means Step FD3, FD4: fuel cut limit means

Continuation of the front page (56) References JP-A-62-246650 (JP, A) JP-A-61-103044 (JP, A) JP-A-5-229368 (JP, A) JP-A-6-1166 (JP) JP-A-6-17673 (JP, A) JP-A-64-85844 (JP, A) JP-A-61-104128 (JP, A) JP-A-1-275229 (JP, A) 64-12938 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60K 41/00-41/28 F02D 29/00-29/06 F02D 41/00-41/40

Claims (1)

(57) [Claims] An automatic transmission having a plurality of gear positions is provided, and fuel supply to an engine is cut off when a predetermined fuel cut condition including at least a substantially full closing of a throttle valve is satisfied. In a vehicle having a fuel cut control means, an automatic engine braking force control device for automatically increasing an engine braking force so as to attain a predetermined traveling state when the vehicle speed increases even when the accelerator is substantially OFF. Shift control means for downshifting the automatic transmission to a low gear where the engine brake operates when the throttle valve is substantially fully closed; and opening the throttle valve during the downshift by the shift control means. Controlling the throttle control means, and controlling the fuel supply by the fuel cut control means during automatic control of the engine braking force. An automatic engine braking force control device, comprising: a fuel cut-off restriction unit for restricting a cutoff.