JP2894085B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission, and more particularly to a shift control when downshifting with an accelerator substantially in an OFF state.

[0002]

2. Description of the Related Art An automatic vehicle having an automatic transmission in which a plurality of gears can be established by selectively engaging a plurality of frictional engagement devices is frequently used. Such an automatic transmission is generally used. The shift speed is changed based on the accelerator operation amount or the throttle valve opening and the vehicle speed. 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 was a problem that the engine braking force was 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. This is disclosed, for example, in JP-A-62-246650 and JP-A-61-103044.

When the downshift is performed automatically to increase the engine braking force when the accelerator is off, the speed ratio of the automatic transmission is increased in the downshift, so that the engine speed is increased accordingly. At the time of such engine braking, the throttle valve is normally closed, so the frictional engagement device on the low-speed side for achieving the shift speed after the downshift, for example, the output side by torque transmission of a hydraulic clutch or a brake. Is transmitted to the engine side, thereby increasing the rotation speed of the engine. At this time, the inertia torque accompanying the increase in the engine rotation speed appears as the braking torque of the vehicle, and when the transmission torque of the hydraulic clutch or the brake is rapidly increased, the engine rotation speed increases rapidly,
Although the shift time is shortened, the braking torque sharply increases, causing a large shift shock. Also, if the transmission torque of the hydraulic clutch or the brake is gently increased to reduce the shift shock, the shift time becomes longer, the amount of friction energy of the hydraulic clutch or the brake increases, and the life of the friction material decreases.

On the other hand, in Japanese Patent Application No. 3-357758 filed earlier, when downshifting while the accelerator is off, the applicant temporarily opens the throttle valve to increase the engine output, thereby increasing the engine output. It was proposed to increase the rotation speed and shorten the shift time required for downshifting. With this configuration, the shift time can be reduced without causing a large shift shock, and the life of the friction engagement device can be prevented from being shortened.

[0005]

However, when the engine output is increased during a downshift as described above,
If the timing of the engine blow-up is shifted with respect to the shift speed change of the automatic transmission, a driving force is generated and the vehicle may be accelerated. That is, if the engine output rises before the friction engagement device on the high speed stage that is released during the downshift starts to slip, the driving force increases in the high speed state and the vehicle accelerates, If the engine output rises after the low-speed side frictional engagement device engaged at the time of shifting is completely engaged, not only the effect of reducing the shift time is not obtained, but also the low-speed state As a result, the driving force increases and the vehicle is accelerated. This is because, after a shift output for performing a downshift is made, there is a delay time until the friction engagement device of the automatic transmission is actually released or engaged, so that, for example, a downshift is performed. Output and the throttle valve opening control are performed at the same time, the engine output may increase before the friction engagement device on the high-speed stage, which is released during downshifting, begins to slip, causing vehicle acceleration. On the other hand, after the throttle valve opening control for increasing the engine output is performed, there is a delay before the engine output actually increases, so the frictional clutch on the high speed stage that is released during the downshift is released. Even if the throttle valve opening control is performed after detecting slippage of the joint device, the engine output increases after the friction engagement device on the low speed side engaged at the time of the downshift is completely engaged. It is at some of the above-described problems can not be stably obtained the shift time shortening effect can not be avoided.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to ensure that a downshift in an accelerator OFF state does not cause vehicle acceleration and that the engine output increase control ensures that the shift time is increased. An object of the present invention is to reduce the life of the friction engagement device by shortening it.

[0007]

In order to achieve the above object, the timing for increasing the engine output is controlled so that the engine output increases while the frictional engagement device of the automatic transmission is slipping. In the present invention, FIG.
As shown in the claim correspondence diagram, an automatic transmission in which a plurality of shift speeds are established by selectively engaging a plurality of friction engagement devices , and an accelerator is substantially O
In the case of the FF state , the vehicle speed is maintained at a predetermined target vehicle speed.
To automatically control the engine braking force
The automatic transmission control apparatus causes a downshift to a lower speed stage where the engine brake is applied to the automatic transmission in response, after the downshift if flat ground running (a)
So that the current vehicle speed can be maintained
The gear position after downshift and the current vehicle speed are parameters
So that the engine output is predetermined as
Increases the actual engine output during downshifts
Engine output increasing means; (b) a timer for measuring an elapsed time from a predetermined measurement start time at the time of the downshift; and (c) a time for the downshift based on the elapsed time measured by the timer. The engine speed is set between the time when the frictional engagement device on the high speed side that is released to slip starts to slip and the time when the frictional engagement device on the low speed side that is engaged during the downshift is fully engaged. And timing control means for increasing the engine output by the engine output increasing means when a predetermined timing time elapses with reference to the measurement start time so as to rise.

[0008]

In such a shift control device for an automatic transmission, when the automatic transmission is downshifted to a low gear where the engine brake operates with the accelerator substantially in the OFF state, the engine output increasing means is used. Although the engine output is caused to increase size, timing of increasing the engine output by the engine output increasing means uses a timer for measuring an elapsed time from a predetermined measurement start time, elapsed time predetermined time Is controlled by the timing control means so as to increase the engine output at the time of the start. The timing time is such that after the frictional engagement device on the high speed side released at the time of the downshift begins to slip, the frictional engagement device on the low speed side engaged at the time of the downshift is completely engaged. The engine rotation speed is set to increase during the period until the vehicle is synchronized, whereby a driving force is generated due to a timing shift of an increase in the engine output with respect to the shift speed change of the automatic transmission, and the vehicle is driven. The problem of acceleration is solved, and the shift time can be shortened reliably while suppressing the shift shock, thereby preventing the life of the friction engagement device from being shortened.

The engine output increasing means may open and control the throttle valve. However, if the engine output increasing means has an idle speed control valve, the engine output increasing means opens and controls the idle speed control valve or an engine auxiliary such as an alternator. It is also possible to increase the engine output by utilizing. Also,
The time at which the elapsed time is measured by the timer is, for example, a time at which a determination to perform a downshift is made or a time at which a shift output is actually made in accordance with the downshift determination. Based on the time point, for example, it is determined in advance by experiments, simulations, or the like so that the frictional engagement device on the high speed stage released at the time of the downshift starts to slip and the engine rotation speed increases at the same time.

[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 DTH supplied from a throttle control computer 35. The valve 20 is provided with a throttle position sensor 36, and outputs a throttle valve opening signal Sθ indicating the throttle valve opening θ to the engine control computer 32, the transmission control computer 34, and the throttle control computer 35. 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 that measures the temperature of the engine cooling water. The water temperature sensor 60 outputs a signal representing the temperature of the engine cooling water to the computer 32 for controlling the engine.
4 is an oxygen sensor 62 for detecting the oxygen concentration in the exhaust gas.
And outputs a signal indicating the oxygen concentration to the computer 32 for engine control. The distributor 50 is provided with a rotation angle sensor that generates a pulse in synchronization with the rotation of the crankshaft, and outputs a pulse signal, that is, an engine rotation speed signal SNE representing the engine rotation speed NE, to the engine control computer 32 and the transmission. Output to the 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, shift control is performed in four steps from 1st to O / D. In the “S (second)” range, 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 the first time, 2nd, 3rd, 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” 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 is connected to the 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 To of the hydraulic oil, and an oil temperature signal STo representing the oil temperature To.
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, the throttle valve opening θ, the engine rotation speed NE, the cooling water temperature of the engine 10, the intake air temperature, the oxygen concentration in the exhaust passage 56, the accelerator operation, and the like. Amount Ac
In accordance with, for example, the fuel injection valve 3 based on a data map or an arithmetic expression determined in advance to reduce fuel consumption and harmful exhaust gas while securing necessary engine output,
It controls the fuel gas injection amount and injection timing by 0, the ignition timing by the igniter 48, the idle speed by the idle speed control valve 38, and the opening and closing timing of the intake and exhaust valves 28 and 42 by the variable valve timing mechanism. The transmission control computer 34 controls the throttle valve opening θ, the engine speed NE, the selection pattern represented by the pattern signal SP, the presence / absence of the brake operation represented by the brake signal SB, and the O / D shift speed represented by the O / D signal SO. Whether or not a shift can be performed, accelerator operation amount Ac, automatic transmission 78
Based like the output shaft rotation speed N _O of the solenoid S
By switching between excitation and non-excitation of S1, S2, and S3, the shift speed of the automatic transmission 78 is switched. 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. In addition, the throttle valve opening θ of the throttle valve 20 is controlled in accordance with the accelerator operation amount Ac, or when the accelerator operation amount Ac is zero, the throttle valve opening θ is adjusted 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.
TH is output.

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 as shown 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 allowed, 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 Vu, it is not necessary to perform an upshift, and it is determined in step S8 whether or not the current shift stage is 1st. If it is 1st, the flag F1 is set to "0" in step S9 and a series of shift determinations is completed. However, if V> Vu, the flag F1 is set to "1" in step S7, and then, in step S15, a gear higher than the current gear is set as the next gear. 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. If V ≦ Vd, step S13 is executed.
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 performed 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 position is, for example, O / D, the vehicle speed V suddenly decreases after the gear shift determination to 3rd is made and before the gear shift to 3rd is actually performed. 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, each downshift vehicle speed Ved is compared with the current vehicle speed V to determine the downshift shift. 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 R6 in FIG. 9 when downshifting is performed to increase the engine braking force in the automatic engine brake control, and when the downshift is completed, "1" is set in step S31 in FIG. If F4 = 0, the flag F2 is set to "0" in step S44 to end the shift determination, and if F4 = 1, step S43 is executed. In step S43, the next low gear at which the engine brake acts as the next gear, that is, 2nd or 1s
In the case of t, the gear position 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.
This 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 that a plurality of shifts are performed in a short time (multi-shift). ), And when the upshift to the O / D gear is made when the accelerator pedal is quickly released to apply the engine brake on the 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 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 5% or less. In step S26, it is determined whether or not the next shift speed set in step S15 is the O / D shift speed. The lower limit vehicle speed V1 and the upper limit vehicle speed V2 define a vehicle speed range in which special control for engine braking is performed. 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. Is set to If any one of the above steps S21 to S26 is NO, in step S28, the change of the next shift speed set in step S15 in step S27 is not performed, but the determination in steps S21 to S26 is made. If all are YES, the next gear is changed to "3rd" in step S27. Step S26 is performed in step S1.
It is determined whether or not the next shift speed set in step 5 is O / D. Even in the cycle after the next shift speed is changed from O / D to 3rd in step S27, the determination in step S26 is Y.
ES.

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. 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.

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 of step S29 is inserted between steps S20 and S21, and the determination of 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. 7, the shift range, the running pattern, the vehicle speed V, and the accelerator operation amount Ac are the same as those in steps S21 to S25. 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.
In step F3, the flag F3 is set to "0"
Is set to "0", and normal throttle control is performed in step SS7. In the normal throttle control in step SS7, the accelerator operation amount A indicated by the accelerator operation amount signal SAc
c, the throttle valve opening TH (Ac) is obtained from a predetermined map or an arithmetic expression, the throttle valve opening TH (Ac) is set to the target throttle valve opening TH, and the target throttle valve TH is set. A throttle command signal SQ indicating the opening TH is output to the throttle control computer 35. Throttle control computer 35
Indicates the actual throttle valve opening θ of the throttle valve 20 by feedback control or the like.
To match the target throttle valve opening TH represented by
A throttle control signal DTH 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 R2 and R4 in FIG. However, if the vehicle speed V is relatively greatly reduced by the operation of depressing the brake, 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 depressing operation is not performed, 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 TH is set to 0 in order to increase the engine braking force, and a throttle command signal SQ indicating the target throttle valve opening TH is output to the throttle control computer 35, thereby turning the throttle valve 20 on. Completely 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 off, and the determination in step SS11 is YES, and the result in step SS14 or SS19
In FIG. 5, 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.

On the other hand, 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 in FIG. 6, the process proceeds to step SS13. The determination is NO, and it is determined in step SS16 whether the flag F6 is "0". The flag F6 is set to “1” in step R6 of FIG. 9 when downshifting is performed to increase the engine braking force. When the flag F6 = 0, the flag F3 is already set to “1” in step SS17. 1 "is determined. If 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,
When the shift output is performed in step S30 in FIG. 6 and the solenoids S1, S2, and S3 are switched between energized and de-energized, the clutch C and the brake B of the automatic transmission 78 begin to slip, and the turbine rotational speed N _T and after the output shaft rotational speed ratio of the rotational speed N _O speed change, that is, the speed change by substantially the same as the speed ratio i of the current speed after the shift output ends, the rotational speed N _T of it such as, N _O , And the gear ratio i of the current gear position is not shifting when the following equation (1) is satisfied, and is shifting when the following equation (1) is not satisfied. Incidentally, according 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.

[0039]

N _T ＮN _O × i (1)

If the determination in step SS18 is YES, that is, if the gear is not being shifted, the automatic engine brake throttle processing routine of step SS21 is executed. If the gear is being shifted, step SS20 is executed.
Also, in the first cycle of the automatic engine brake control, the flag F3 is not "1", and the determination in step SS17 is N
In the case of O, after setting the flag F3 to "1" in step SS19, step SS20 is executed, and the same normal throttle control as in step SS7 is performed.

In the automatic engine brake throttle processing routine in 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 in 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 or not the actual throttle valve opening θ represented by the throttle valve opening signal Sθ is smaller than a predetermined determination value θ1. The determination value θ1 is a small value of about 5% or less, and can be determined using an idle signal or the like indicating that the throttle valve opening θ is substantially fully closed. If θ ≧ θ1, that is, if the engine braking force can be increased by closing the throttle valve opening θ, step R2 is executed, and according to the deviation between the target vehicle speed Vm and the current vehicle speed V, Then, the throttle valve opening TH3 (%) for making the vehicle speed V substantially equal to the target vehicle speed Vm is calculated according to an arithmetic expression of feedback control.

In the next step R3, 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 THm
(%) 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 TH3 is smaller than the throttle valve opening THm. 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 experimentally obtained data as shown in FIG. . 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), gear transmission efficiency is 0.855, and tire effective radius is 0.306 m. For example, when the vehicle speed is 80 km / h, the throttle valve opening THm (%) is flat. Since the throttle valve opening (angle) at point B, which coincides with the running resistance on the ground, is approximately 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
Throttle valve opening TH ₄₅ in the case of 0 km / h is specifically a 9.3%, the throttle valve opening TH ₄₁ to TH ₄₇ of the vehicle speed in this way O / D gear stage is sought 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 TH ₃₁ to
_{TH 37, TH 21 ~TH 27,} TH 11 ~TH 17 is required. As is clear from the data in FIG. 12, the throttle valve opening THm increases as the vehicle speed increases, and the throttle valve opening THm increases as the speed ratio increases at low speeds at the same vehicle speed.

If TH3 <THm, the throttle valve opening TH3 is set to the target throttle valve opening TH in step R4, and the target throttle valve opening TH is set.
Is output to the throttle control computer 35, whereby the throttle valve 20 is output.
The actual throttle valve opening θ is equal to the throttle valve opening TH3
Is controlled so that These steps R2, R3,
By repeatedly executing R4, 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 decreases. Thus, the engine braking force for running the vehicle at the changed target vehicle speed Vm is obtained. In this embodiment, since the throttle valve opening θ is feedback-controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, the engine is controlled so that the vehicle speed V substantially matches the target vehicle speed Vm irrespective of a change in the road surface gradient. When the braking force is increased or decreased to change 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.

On the other hand, if TH3 ≧ THm, the determination in step R3 is NO, and in step R5, the throttle valve opening THm is set to the target throttle valve opening TH, and the throttle command representing the target throttle valve opening TH is set. By outputting the 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 THm. This is because the engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm regardless 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 slope, and when driving on a flat ground. If there is target vehicle speed V
m is maintained as the upper limit of the throttle valve opening TH3 by feedback control. As a result, the target vehicle speed V on a downhill or flat ground
m is maintained, but on an uphill, the vehicle speed V depends on the gradient.
Becomes lower than the target vehicle speed Vm, and the traveling control as intended by the driver is performed.

When the throttle valve 20 is substantially fully closed and the engine braking force cannot be increased by the above throttle control, the determination in step R1 is YES, and the steps from step R6 are executed. In step R6, the flag F4 for instructing a downshift to increase the engine braking force is set to "1", and the flag F6 representing the throttle control at the time of the downshift is set to "1". When the flag F4 is set to "1", step S43 in FIG. 5 is executed, and when the flag F6 is set to "1", steps SS24 and subsequent steps in FIG. 8 are executed. . Further, in step R7, based on the gear position after the downshift and the current vehicle speed V, the throttle valve opening capable of maintaining the current vehicle speed V when traveling on flat ground, that is, the driving force in consideration of the running resistance becomes zero. The throttle valve opening TH4 (%) is calculated from the data map shown in FIG. 11 by map interpolation in the same manner as the throttle valve opening THm. In step R8, the throttle valve opening change timing time T2 is set and the timer is set. Reset Tb. Such a timer Tb
Is YES in step R1 so that a downshift for increasing the engine braking force is performed,
The time when step R8 is executed is set as the measurement start time, and the elapsed time thereafter is measured.

The throttle valve opening TH4 is determined by the throttle valve 20 during the downshift when the accelerator is off.
The opening speed is controlled so as to quickly increase the engine rotational speed NE and shorten the shift time. Further, the throttle valve opening change timing time T2 is a delay time from when the timer Tb is reset in step R8 to when the throttle valve 20 is actually opened and controlled. The output of the gearshift is performed, and the engine rotation speed N is synchronized with the timing at which the clutch C and the brake B on the high speed stage which are released by the downshift begin to slip.
The type of shift, the vehicle speed V, the oil temperature To of the hydraulic control circuit 150, and the like are used as parameters to calculate E from a map determined in advance by experiments, simulations, and the like so that E increases in accordance with the throttle valve opening TH4. . In this map, the flag F4 is set to 1 so that step S4 is performed.
After the downshift is set at 43, step S
30 is determined in consideration of the delay time until the shift output is actually performed, that is, the shift timing time T1.

Here, referring to FIG. 14 which is a time chart when downshifting from the O / D shift stage to the 3rd shift stage, the throttle valve opening change timing time T
2 will be specifically described. First, at time t1, a shift output is performed in step S30, and when the solenoid S2 is turned on (excited), the valve of the hydraulic control circuit 150 is switched to be released at the time of O / D → 3rd downshift. The engagement hydraulic pressure P _B0 of the brake B ₀ , which is the friction engagement device of the O / D shift stage, is reduced, and the friction engagement device of the 3rd shift stage is engaged during the O / D → 3rd downshift. there engaging pressure P _C0 of the clutch C ₀ is raised. The time t2 is equal to the engagement hydraulic pressure P.
In _BO time brake B ₀ began slipping with decreasing, the time t4, the throttle valve 20 is in the case of the fully closed state in response to the accelerator operation amount Ac, of the output side by the torque transmission of the clutch C ₀ By transmitting the torque to the engine 10, the engine rotational speed NE is increased as shown by the solid line, and the rotational speeds of the output side and the input side of the automatic transmission 78 are changed to the gear ratio after the downshift. is the time clutch C ₀ has been completely engaged by synchronizing in accordance with the time from the time t2 to t4 (t4-t2) is the shift time. In this embodiment, the shift time is shortened by temporarily opening the throttle valve 20 and increasing the engine speed NE during this shift, but before the time t2 or at the time t2.
When the engine rotational speed NE increases after 4, the driving force is generated and the vehicle is accelerated. Therefore, in order to obtain the effect of reducing the shift time without causing the vehicle acceleration, at least the time from the time t2 to the time t4 is required. The engine speed N
It is necessary to determine the throttle valve opening change timing time T2 so that E increases. In this case, the delay time from the solenoid output t1 to the slip start time t2 of the friction engagement device fluctuates depending on the type of shift, the vehicle speed V, the oil temperature To, and the like, and from the opening control of the throttle valve 20 to the engine rotational speed NE. The delay time until the vehicle rises is the vehicle speed V
The change timing time T2 is set using these as parameters. In the present embodiment, the frictional engagement device on the high-speed gear stage that is released at the time of the downshift, the brake B in the O / D → 3rd downshift is used.
A map for determining the change timing time T2 is determined so that the engine rotational speed NE starts to increase almost at the same time as the start of the _zero slip. The rotation speed N _C0 in FIG. 14 is the rotation speed of the housing of the clutch C ₀ , in other words, the rotation speed of the sun gear 124 in the first transmission 112.

When the flag F6 is set to "1" at step R6, in the subsequent cycle, the process proceeds to step SS1 in FIG.
The determination at 6 is NO, and step SS24 is executed.
In step SS24, it is determined whether or not the time counted by the timer Tb is equal to or longer than the throttle valve opening change timing time T2.
In S25, the throttle valve opening TH4 is set to the target throttle valve opening TH, and the target throttle valve opening TH is set.
Is output to the throttle control computer 35, whereby the throttle valve 20 is output.
The actual throttle valve opening θ is equal to the throttle valve opening TH4
Is controlled so that In the next step SS26, it is determined whether or not the flag F4 = 0, and when the flag F4 = 0, it is determined in step SS27 whether or not the shift is completed.
Whether or not the shift has been completed is determined by the shift stage after the shift output, that is, the solenoids S1 and S1 as in step SS18.
2, the gear ratio i of the current gear, as determined from the excitation state of S3,
And rotational speed N _T, is determined from the based on N _O (1) formula, when the shift is completed, by the flag F6 is set to "0" in step SS28, in the subsequent cycle following step SS16 step SS17 and below are executed. Accordingly, regardless of whether the opening control of the throttle valve 20 is performed before or after the shift output of the downshift, the throttle valve opening θ is maintained at TH4 until the shift is completed. Note that the throttle valve opening change timing time T2
Is always longer than the shift timing time T1, in other words, the throttle valve 20 is lower than the shift output of the downshift.
If the opening control is always slower, step SS26
Can be omitted, and the flag F4
Is set as the throttle valve opening change timing time T2 based on the time point when the value of the throttle valve 20 is changed from "1" to "0", and the flag F4 is changed from "1" to "0". The elapsed time from the time point “0” may be measured by the timer Tb.

As described above, in this embodiment, when the downshift is performed when the accelerator is turned off in order to increase the engine braking force, the throttle valve opening at which the current vehicle speed V is maintained even at the shift speed after the downshift Since the throttle valve 20 is controlled to open until TH4, the engine speed NE is quickly increased, the shift time is shortened, and the life of the friction materials of the clutch C and the brake B is prevented from being shortened.
In particular, in the present embodiment, the timing of controlling the opening of the throttle valve 20 is controlled so that the engine rotational speed NE increases in accordance with the timing at which the clutch C and the brake B on the high speed stage that are released by the downshift begin to slip. Since it is determined on the basis of the type of shift, the vehicle speed V, the oil temperature To, etc., for example, before the clutch C or the brake B on the high speed stage released at the time of the downshift starts to slip,
Alternatively, the engine speed NE increases after the clutch C and the brake B on the low speed side engaged at the time of the downshift are completely engaged, and there is no danger that the driving force increases and the vehicle accelerates. The shift time can be shortened most efficiently. The graph shown by the dashed line with respect to the rotation speed and the driving torque in FIG. 14 is for the present embodiment, and the time t3 is the shift end time.

The line hydraulic pressure PL of the hydraulic control circuit 150 is generally controlled in accordance with the throttle valve opening θ, and when the throttle valve 20 is controlled to open as described above, the line hydraulic pressure PL is reduced. The hydraulic pressure of the clutch C and the brake B is also increased.
The shift time is further shortened by rapidly and completely engaging the clutch C and the brake B on the low speed side. However, in that 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 SS25, the line oil pressure PL is controlled to a low oil pressure when the throttle valve 20 is fully closed.

In this embodiment, of the series of signal processing performed by the transmission control computer 34, the part for executing steps R8 and SS24 corresponds to the timing control means, and the part for executing steps R7 and SS25 corresponds to the throttle control computer. 35, together with the throttle valve 20, constitute an engine output increasing means.

On the other hand, in the automatic engine brake control of this embodiment, the vehicle speed V when the accelerator is turned off is set to the target vehicle speed Vm in step SS10, and the vehicle speed V substantially matches the target vehicle speed Vm. As described above, in steps R2 and R4, the throttle valve opening θ is feedback-controlled or downshifted to control the engine braking force. When the accelerator is released, the vehicle speed V when the accelerator is released is set as the target vehicle speed Vm,
The vehicle speed is controlled to the driver's intention by the engine brake.

If the driver steps on the brake for further deceleration during the control of the automatic engine braking, the step SS10 is executed every time the determination in step SS9 becomes NO with the decrease of the vehicle speed V. Then, the target vehicle speed Vm is sequentially changed according to the vehicle speed V at that time. Therefore, when the brake is released after the vehicle speed has decreased to the desired vehicle speed, the vehicle speed V at the time of releasing the brake is set to the target vehicle speed Vm, and thereafter, based on the new target vehicle speed Vm at the time of releasing the brake. The engine braking force is controlled by throttle control and downshift. This eliminates the risk of sudden acceleration due to lack of engine braking force after the brake is released.For example, even if the driver depresses the brake before decelerating the straight line on a downhill, decelerates, and then releases the brake and travels on the curve, And the driving operation is further facilitated.

In this embodiment, if the brake is depressed during the automatic engine brake control, the throttle valve 20 is fully closed in step SS22 regardless of the throttle control in steps R2 and R4.
Since the engine braking force is increased, engine braking control that matches the intention of the driver desiring deceleration is performed, and the burden on the driver and the foot brake is reduced, for example, the braking force is reduced.

In steps R2 and R4, the vehicle speed V
Is adjusted so that the throttle valve opening θ matches the target vehicle speed Vm.
The engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm irrespective of a change in the road surface gradient. The vehicle speed V is prevented from being reduced against the driver's intention due to excessive effect. In particular, in this embodiment, since the throttle valve opening θ is feedback-controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, the vehicle speed V is quickly brought close to the target vehicle speed Vm, and an appropriate engine braking force is quickly obtained. There are advantages to be gained.

Further, in this embodiment, if the throttle valve opening TH3 obtained in the above step R2 becomes equal to or larger than the throttle valve opening THm capable of maintaining the target vehicle speed Vm when traveling on flat ground, the flow proceeds to step R5. In this case, the throttle valve opening THm is set to the target throttle valve opening TH, so that if there is an uphill after a downhill, the vehicle speed V is made lower than the target vehicle speed Vm according to the gradient. The running control is performed as intended by the driver who thinks that the vehicle speed V will decrease.

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 embodiment, the throttle valve 20
Although the engine output is increased by the opening control, the engine output can be increased by using an engine auxiliary such as an alternator or by opening and controlling the idle speed control valve 38.

In the above embodiment, the throttle valve opening θ
Has been described for a vehicle controlled by the throttle control computer 35, but the present invention is also applicable to a vehicle in which the throttle valve 20 is mechanically connected to an accelerator pedal and opened and closed. The configuration of the automatic transmission 78 and the number of shift stages can also be changed as appropriate.

[0060] Further, after the shift end of the downshift in the embodiment, it had become earthenware pots by you close gradually by the throttle valve 20 to step R2, R4, after the shift end,
The throttle valve opening θ can be controlled so that a braking torque substantially equal to or slightly larger than the braking torque before the shift is obtained. A data map for obtaining the throttle valve opening in this case can be created in advance using the data of FIG. 12 and the like with the gear position and the vehicle speed V as parameters, similarly to the data map of FIG.

In the above embodiment, the accelerator operation amount Ac
Is controlled to open the throttle valve 20 when the downshift is performed in a substantially complete OFF state of about 5% or less. However, even if the accelerator is not in the complete OFF state, the drive torque is negative. At times, the effect of the present invention can be obtained by controlling the opening of the throttle valve 20. Whether the drive torque is negative or not can be detected, for example, by comparing the engine rotation speed NE with the turbine rotation speed _NT of the torque converter 110.

[0062] The front although the you施例adapted to be automatic engine brake control step SS8 following, subject to the automatic engine braking pattern is selected by the pattern select switch 70 is executed, the power pattern Such as performing automatic engine brake control when other driving patterns are 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.

[0063] The front although the it施例speed limiting step SS3 and SS4 as a condition for performing automatic engine brake control is provided, with such speed limit is not always necessary, the range of the vehicle speed limit is suitably determined . Another condition may be added as a condition for performing the automatic engine brake control.

[0064] Also, step SS for each becomes the decision NO in step SS9 with decreasing vehicle speed V is in front you施例
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.

[0065] In the front it施例step S2 of FIG. 6
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 in step S27 the next gear is returned. Is changed to 3rd, step S30 may be executed immediately before the shift timing time T1 is reached to output the shift.

[0066] Further, before although the vehicle speed V at the time of or during the brake release accelerator OFF at you施例was so it is the target vehicle speed Vm, a target vehicle speed Vm is not necessary to exactly match the vehicle speed V Alternatively, 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 a measurement error or the like.

[0067] In addition, the target vehicle speed V of the vehicle speed V is in front of you施例
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 ΔTH, 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 ΔTH 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 similarly applied to other automatic engine brake control such as controlling the engine braking force so that the acceleration becomes negative.

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 embodied with various modifications and improvements 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, an engine, and the like including a shift control device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of the automatic transmission of 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 at which a driving force in consideration of a shift speed and a vehicle speed and a running resistance becomes substantially zero in the throttle control of FIG. 8;

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 shows the automatic transmission of FIG.
6 is a time chart showing changes in hydraulic pressure, rotation speed, and the like when downshifting to a shift speed.

[Explanation of symbols]

10: engine 20: throttle valve 34: transmission control computer 35: throttle control computer 78: automatic transmission Tb: timer T2: throttle valve opening change timing time Vm: target vehicle speed step SS25, R7: engine output increasing means step SS24, R8: Timing control means

Continuation of front page (56) References JP-A-3-22932 (JP, A) JP-A-5-229368 (JP, A) JP-A-5-214978 (JP, A) JP-A-5-162570 (JP) , A) JP-A-62-155141 (JP, A) JP-A-62-246650 (JP, A) Patent 2707907 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 29 / 00-29/06 B60K 31/00-31/18 B60K 41/00-41/28 F02D 41/00-41/40

Claims (1)

(57) [Claims] 1. An automatic transmission in which a plurality of gears are established by selectively engaging a plurality of frictional engagement devices, wherein an automatic transmission is provided when an accelerator is substantially in an OFF state .
Engine brakes so that the vehicle speed maintains the specified target vehicle speed
In order to automatically control the keying force, in a shift control device for an automatic transmission that downshifts the automatic transmission to a low gear where the engine brake acts as necessary, if the vehicle is traveling on flat ground, In the gear
Even after the downshift so that the current vehicle speed can be maintained
The gear position and the current vehicle speed are predetermined as parameters.
During the downshift so that the engine output
Engine output increasing means for increasing the actual engine output
When the timer for measuring the elapsed time from a predetermined measurement starting point when the downshift, based on the elapsed time measured by the timer, friction of higher gear to be released during the downshift The measurement start time is set such that the engine rotation speed increases until the low-speed-stage friction engagement device engaged at the time of the downshift is completely engaged after the slip device starts to slip. A shift control device for an automatic transmission, further comprising: timing control means for increasing the engine output by the engine output increasing means when a predetermined timing time has elapsed as a reference.