JPH0687356A - Engine brake force automatic control device - Google Patents

Abstract

PURPOSE:To increase the control range of engine brake force by providing a clutch engaging means to engage a direct-coupling clutch when an engine output is reduced to approximately the lowest level by an engine output control means. CONSTITUTION:When an automatic transmission 78 is downshifted to the lowest speed stage at which an engine brake will act by a transmission control means 34 on steep downhill, and an engine output is reduced to approximately the lowest level by an engine output control means 32, a direct-coupled clutch arranged in parallel to a fluid coupling is engaged with a clutch engaging means to connect an automatic transmission 78 directly to an engine. Because a slip loss by the fluid coupling is eliminated, an engine brake force is increased accordingly, and the control range of the engine brake force in which braking operation is not required is increased to further facilitate the operation control. Also the feeling of lack of engine brake force is produced correspondingly less to improve the operating feeling.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Automatic vehicles equipped with an automatic transmission having a plurality of gears are often used. However, such an automatic transmission generally has a gear based on an accelerator operation amount or a throttle valve opening and a vehicle speed. It is supposed to be changed. FIG. 10 is an example of a shift map of an automatic transmission having four shift stages. The shift stages can be switched based on the accelerator operation amount and the vehicle speed. The solid line is the shift map on the upshift side and the broken line is the shift map. It is a shift map on the downshift side. Such a shift map is usually designed to upshift depending on the vehicle speed even when the accelerator operation amount is zero, that is, in the OFF state. Therefore, even when the accelerator pedal is released on a downhill, sufficient engine braking force is obtained. If the vehicle speed increases without being obtained, there is a problem that the engine braking force further decreases due to an upshift. As a countermeasure against this, if the acceleration of the vehicle is non-negative or the vehicle speed continues to increase for a certain period of time with the accelerator off, the engine braking force is increased by downshifting to increase the gear ratio of the automatic transmission. For example, Japanese Patent Laid-Open No. 62-246650 and Japanese Patent Laid-Open No. 6-246650
It is disclosed in Japanese Patent Publication No. 1-103044.

[0003]

However, when the engine braking force is increased by the downshift in this way, the engine rotation speed is increased according to the change of the gear ratio of the automatic transmission accompanying the downshift, and the engine brake is increased. Since the force suddenly increases, there is a problem that a shock occurs and the riding comfort is not good, and that the engine braking may be too effective and accelerator operation may be required. Such an accelerator operation at the time of engine braking is not preferable for an automatic vehicle aiming at easy driving operation, and it is desired to obtain an appropriate engine braking force without requiring an accelerator operation.

Further, if the automatic transmission cannot downshift to the lowest speed where the engine brake acts on a steep downhill and the like and sufficient engine braking force cannot be obtained, the engine brake is considered to be automatically controlled. It is necessary to increase the control range of the engine braking force so that the driver may feel a shortage of the engine braking force and the braking operation is required.

The present invention has been made in view of the above circumstances. An object of the present invention is to reduce the shock caused by a sudden increase in engine braking force due to a downshift and to require an accelerator operation. The aim is to obtain an appropriate engine braking force without increasing the control range of the engine braking force.

[0006]

In order to achieve the above object, the engine braking force is made substantially equal before and after the downshift, and a direct coupling clutch arranged in parallel with the fluid coupling is engaged. The slip loss of the engine brake may be eliminated by the present invention. According to the present invention, as shown in the claim correspondence diagram of FIG. 1, (a) an automatic transmission having a plurality of gear stages and (b) a fluid A fluid coupling for transmitting engine output to the automatic transmission,
(C) In a vehicle provided with a direct coupling clutch that is arranged in parallel with the fluid coupling and that directly couples the automatic transmission to an engine, a predetermined predetermined traveling is performed when the vehicle speed increases even when the accelerator is in a substantially OFF state. An engine braking force automatic control device for automatically increasing the engine braking force so as to be in a state, wherein (d) the automatic transmission is down-shifted to a low speed stage where the engine braking acts when the engine output becomes substantially minimum. During the downshift by the shift control means for shifting and (e) the shift control means, the engine output is increased so that the driving force before and after the downshift becomes approximately the same, and the engine output is reduced after the downshift is completed. The engine output control means and (f) the minimum speed at which the automatic transmission operates by the engine brake by the shift control means. With the downshift to the step, when the engine output is reduced to substantially a minimum by the engine output control means, and having a clutch engaging means for engaging the lockup clutch.

[0007]

In such an engine braking force automatic control device, when the automatic transmission is downshifted by the shift control means to increase the engine braking force, the driving force before the downshift and the downshift are performed. Since the engine output is increased by the engine output control means so that the driving force after the shift becomes substantially equal,
The engine braking force before and after the downshift is made substantially the same, and a rapid increase in the engine braking force due to the downshift is prevented. As a result, the shock caused by the sudden increase in the engine braking force is reduced, the riding comfort is improved, and the engine braking force is increased by the subsequent engine output reduction control.
It is possible to obtain an appropriate engine braking force that brings the vehicle into a predetermined running state without requiring an accelerator operation.

On the other hand, on a steep downhill or the like, the shift control means downshifts the automatic transmission to the lowest speed stage where the engine brake acts, and the engine output control means reduces the engine output to approximately the minimum. In this case, the direct coupling clutch arranged in parallel with the fluid coupling is engaged by the clutch engaging means, and the automatic transmission is directly coupled to the engine. Therefore, the slip loss due to the fluid coupling is eliminated and the engine braking force is increased by that amount, the control range of the engine braking force that does not require the brake operation is expanded, and the driving operation is further facilitated. The feeling of insufficient engine braking force is less likely to occur and the driving feeling is improved.

[0009]

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

In FIG. 2, in the combustion chamber 12 of the gasoline engine 10, 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 taken in through the intake valve 28,
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 intake air amount, and outputs a signal representing the intake air amount to the engine control computer 32. Throttle valve 20
Is for continuously changing the amount of air taken into the engine 10. The throttle valve opening θ is controlled according to the throttle control signal DTA supplied from the throttle control computer 35, and The valve 20 is provided with a throttle position sensor 36, and 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 fully closed to the computers 32, 34 and 35 together with the throttle valve opening signal Sθ. Bypass passage 2
2 is arranged in parallel with the throttle valve 20, and the idle speed control valve 3 is provided in its bypass passage 22.
8 is provided, and an engine control computer 32
By controlling the opening of the idle speed control valve 38, the amount of air that bypasses the throttle valve 20 is adjusted, and the engine speed during idling is controlled. The injection timing and the injection amount of the fuel injection valve 30 are also controlled by the engine control computer 32. An intake air temperature sensor 40 that measures the temperature of intake air is provided upstream of the air flow meter 16, and a signal representing the intake air temperature is sent to the engine control computer 32.
Output to.

The engine 10 includes an intake valve 28 and an exhaust valve 4
2, a piston 44, and an ignition plug 46. The ignition plug 46 generates an ignition spark by a high voltage supplied from an igniter 48 controlled by the engine control computer 32 through a distributor 50. , The crankshaft is rotated by exploding the mixed gas in the combustion chamber 12 and moving the piston 44 up and down. The intake valve 28 and the exhaust valve 42 are adapted to be opened and closed by a cam shaft which is rotationally driven in synchronization with the rotation of the crankshaft, and by a variable valve timing mechanism (not shown) controlled by the engine control computer 32. The opening / closing timing is adjusted by changing the rotational phases of the camshaft and the crankshaft. Then, the exhaust gas burned in the combustion chamber 12 is exhausted from the exhaust valve 42 to the exhaust manifold 5
4, the exhaust passage 56, and the catalyst device 58 to be discharged to the atmosphere. The engine 10 is provided with a water temperature sensor 60 for measuring the engine cooling water temperature, which outputs a signal representing the engine cooling water temperature to the engine control computer 32, and the exhaust manifold 5
4 is an oxygen sensor 62 for detecting the oxygen concentration in the exhaust gas.
Is provided and outputs a signal representing the oxygen concentration to the engine control computer 32. Further, the distributor 50 is provided with a rotation angle sensor 51 that generates a pulse in synchronization with the rotation of the crankshaft. The pulse signal, that is, the engine rotation speed signal SNE representing the engine rotation speed NE is sent to the engine control computer 32 and Output to the transmission control computer 34.

The engine control computer 32, the transmission control computer 34, and the throttle control computer 35 are all CPU, RAM, R.
The transmission control computer 34 is configured to include an OM, an input / output interface circuit, an A / D converter, and the like, and uses the temporary storage function of the RAM to perform signal processing in accordance with a program stored in advance in the ROM. In addition to the above signals, is a pattern signal SP indicating a selection pattern from the pattern select switch 70, a brake signal SB indicating that the brake is operated by the brake lamp switch 72, and an overdrive switch 74 to an O / D shift stage. O / indicating gear shift permission
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 engine control computer 32 and the throttle control computer 35. The pattern select switch 70 has at least an automatic engine braking pattern for automatically increasing engine braking on a downhill road, etc., and also has a power pattern and fuel consumption for performing shift control of the automatic transmission 78 based on a shift map emphasizing power performance. This is for the driver to select a desired driving pattern from a plurality of predetermined driving patterns such as an economy pattern in which gear shift control is performed according to a priority shift map. Further, the brake lamp switch 72 is arranged in the vicinity of the brake pedal, and is turned on or off depending on whether or not the brake pedal is depressed.
It is composed of an ON-OFF switch or the like for switching F.

The automatic transmission 78 comprises a first transmission 112 and a second transmission 114, as shown in FIG. 3, for example, and is connected to the engine 10 via a torque converter 110. Torque converter 110
Corresponds to a fluid coupling for transmitting an engine output via a fluid. The pump impeller of the torque converter 110 is connected to the crankshaft 118 of the engine 10, while the turbine impeller has an input shaft 120. It is connected to the carrier 122 of the first transmission 112 via. Also,
A direct coupling clutch 116 is provided in parallel with the torque converter 110, and the input shaft 120 is directly coupled to the crankshaft 118 of the engine 10. The direct coupling clutch 116 is adapted to be engaged and released by switching the distribution path of the hydraulic oil supplied from the hydraulic control circuit 150. The distribution path of the hydraulic oil is solenoid-operated by the transmission control computer 34. It is changed by switching the excitation and non-excitation of S4.

The first transmission 112 has a sun gear 12
4, a planetary gear set including a ring gear 126 and a planetary gear 128 rotatably arranged on the carrier 122 and meshed with the sun gear 124 and the ring gear 126. The clutch C ₀ and the one-way clutch F ₀ are provided in parallel, and the brake B ₀ is provided between the sun gear 124 and the housing 130. Second
The transmission 114 includes a sun gear 132 and a pair of ring gears 1.
34, 136, a planetary gear 140 rotatably arranged on the carrier 138 and meshed with the sun gear 132 and the ring gear 134, and a planetary gear 144 rotatably arranged on the carrier 142 and meshed with the sun gear 132 and the ring gear 136. And a compound type planetary gear device including the following: a clutch C ₁ is provided between the ring gear 136 and the ring gear 126 of the first transmission 112, and between the sun gear 132 and the ring gear 126. Is provided with a clutch C ₂ , and a brake B is provided between the sun gear 132 and the housing 130.
₁ and a one-way clutch F ₁ and a brake B ₂ arranged in series are provided in parallel, and a brake B ₃ and a one-way clutch F ₂ are provided in parallel between the carrier 138 and the housing 130. There is. In addition, the ring gear 13
4 and the carrier 142 are integrally connected to the output shaft 146, and the output shaft 146 is connected to the drive wheels via a differential gear device or the like.

The clutches C _{0 to} C ₂ and the brake B
_{0 to} B ₃ (hereinafter, unless otherwise distinguished, the clutch C,
The brake B) is a hydraulic friction engagement device that is engagement-controlled by a hydraulic actuator such as a multi-plate clutch or band brake, and hydraulic oil is supplied from the hydraulic control circuit 150 to the hydraulic actuator. Has become. The hydraulic control circuit 150 is provided with a large number of switching valves and the like, and by switching the excitation and non-excitation of the solenoids S1, S2, and S3 in accordance with a signal from the transmission control computer 34, the hydraulic circuit is switched. The clutch C and the brake B are selectively engagement-controlled, and as shown in FIG. 4, any one of the four forward gears is established. In FIG. 4, the "○" mark in the solenoid column means excitation, and the "○" mark in the clutch and brake columns means engagement. Shift position "D", "S",
“L” is the operating range of the driver's shift lever,
In the "D (drive)" range, gear shift control is performed in four speeds from 1st to O / D, and in the "S (second)" range, gear shift control is performed in two speeds, 1st and 2nd.
In the (low) range, it is fixed to the 1st gear. The gear ratio (rotational speed of the input shaft 120 / rotational speed of the output shaft 146) is the largest at 1st, 2nd, 3rd, O / D.
It becomes smaller as becomes, and the gear ratio of 3rd is 1.0. Further, in the "D" range, the engine brake acts at 3rd and O / D, and the engine brake does not work at 1st and 2nd due to the action of the one-way clutches F ₂ and F ₁ , but they are shown in parentheses ( 1st),
At (2nd), the brakes B ₃ and B ₁ are engaged by exciting the solenoid S3, and the engine brake is activated. 2n of "S" range
The engine brake operates even at the first position in the d and "L" 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 shift speed.

The automatic transmission 78 is provided with a pair of rotation speed sensors 80 and 82. The rotation speed sensor 80 is the input shaft 120, that is, the torque converter 11.
The rotational speed sensor 82 detects the rotational speed N _T of the turbine impeller of 0, the rotational speed sensor 82 detects the rotational speed N _O of the output shaft 146, and the rotational speed signals representing the rotational speeds N _T and N _O , respectively. SN _T, and outputs the 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", from the position of the manual shift valve that is switched by operating the shift lever.
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 oil pressure control circuit 150 is also provided with an oil temperature sensor 86 for detecting the oil temperature (A / T oil temperature) THO of the hydraulic oil.
An oil temperature signal STHO indicating HO is output to the transmission control computer 34.

The control computers 32 and 3 are
Necessary information is transmitted and received between Nos. 4 and 35, and the throttle valve opening signal Sθ, the engine speed signal SNE, and the accelerator operation amount signal SAc are at least one of the control computers 32, 34 ,. Alternatively, it may be supplied to 35. Further, various other signals representing the operating state of the vehicle, such as the steering angle of the steering wheel, the gradient of the road surface, and the exhaust temperature, are taken in to control the engine, the shift control of the automatic transmission 78, the throttle control, and the direct coupling clutch 116. It is also possible to use it for the engagement release control of.

Then, the engine control computer 32 uses 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. Quantity Ac
In accordance with the above, for example, the fuel injection valve 3 is based on a predetermined data map or an arithmetic expression so as to reduce fuel consumption and harmful exhaust gas while securing a required engine output.
It controls the injection amount and injection timing of the fuel gas by 0, the ignition timing by the igniter 48, the idle speed by the idle speed control valve 38, the opening and closing timing of the intake and exhaust valves 28, 42 by the variable valve timing mechanism, and the like. 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 stage represented by the O / D signal SO. Whether or not shifting is possible, accelerator operation amount Ac, automatic transmission 78
Based on the output shaft rotation speed N _{O of the} vehicle
By switching the excitation and non-excitation of the solenoids S1, S2, and S3, the shift stage of the automatic transmission 78 is controlled to be switched. The transmission control computer 34 also controls the solenoid S4 to be energized or de-energized to control the engagement / disengagement of the direct coupling clutch 116, and to change the throttle valve opening θ of the throttle valve 20 to the accelerator operation amount. In order to control the engine braking force by adjusting the throttle valve opening θ when the accelerator operation amount Ac is zero, the throttle control computer 35 is controlled by the throttle command signal S.
It is designed to output Q. The throttle control computer 35 basically determines the throttle command signal SQ.
Accordingly, the throttle control signal DTA for controlling the throttle valve opening θ is output.

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

The automatic transmission 7 is executed after step S1 in FIG.
8 is a portion for performing a shift determination as to whether or not to switch the shift stage, and if step S40 is NO, that is, flag F3
Is not "1". The flag F3 is shown in FIG.
When all the conditions of steps SS1 to SS5 are satisfied and the automatic engine braking control is executed, it is set to “1” in step SS14 or SS19 of FIG. 8, and any one of the conditions of steps SS1 to SS5 is satisfied. If not, it is set to "0" in step SS6,
Steps S1 and subsequent steps are executed in the case of normal shift control in which automatic engine braking control is not performed.

In step S1, it is determined based on the O / D signal SO whether or not shifting to the O / D shift stage is possible, and the O / D signal SO is OFF, that is, the O / D shift stage is prohibited. If so, the current O /
It is determined whether or not it is the D shift stage. The current gear stage is determined by the output state of the excitation signal for exciting the solenoids S1, S2, S3. Where O now
The / D shift stage means that the overdrive switch 74 has been turned OFF while traveling at the O / D shift stage. In this case, the flag F2 is determined in step S14.
Is set to "1" and then "3rd" is set as the next gear in step S15. When the determination in step S1 is NO, that is, when the O / D gear is allowed, or even when the determination in step S1 is YES, the determination in step S2 is NO and the current 3rd is not the O / D gear.
Otherwise, if the determination in step S3 is no, then step S4 is executed. In step S4, it is determined whether or not the current shift speed is the O / D shift speed, and if it is not the O / D shift speed, it is determined whether or not upshift is performed by executing step S5 and the following steps. .

In step S5, a predetermined upshift map is searched to obtain the upshift vehicle speed Vu. As shown by the solid line in FIG. 10, the upshift map is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V. The smaller the accelerator operation amount Ac is, the larger the vehicle speed V is. It is designed to be upshifted to the high speed side. Shift up 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 Compare
Determine 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. If it is 1st, the flag F1 is set to "0" in step S9, and a series of gear shift determination is completed. However, if V> Vu, the flag F1 is set to "1" in step S7, and then, in step S15, the shift speed higher than the current shift speed is set as the next shift speed. In this case, even if the current gear stage is, for example, 2nd, the accelerator operation amount Ac sharply decreases after the gear shift determination to 3rd is made and before the gear stage is actually switched to 3rd. When the "3 → O / D" upshift line is exceeded, the O / D gear is set. In step S5, the shift-up vehicle speed Vu for all upshift lines is obtained from the current accelerator operation amount Ac, and in step S6, the respective shift-up vehicle speed Vu and the current vehicle speed V are compared to determine the upshift gear shift. Do it.

If the determination in step S3 is YES,
If the determination in step S4 is YES, or
If the result of the determination at 8 is NO, the process from step S10 is executed to determine whether to downshift. Step S
In step 10, a predetermined downshift map is searched to obtain the downshift vehicle speed Vd. As indicated by the broken line in FIG. 10, the downshift map is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, and as the accelerator operation amount Ac increases and the vehicle speed V decreases. It is designed to downshift to the lower speed side. The downshift vehicle speed Vd is the accelerator operation amount A.
It is determined according to the downshift map based on c, and in the next step S11, the current vehicle speed V corresponding to the output shaft rotation speed N _O is compared with the above-mentioned downshift vehicle speed Vd, and it is determined whether or not a downshift is performed. To do. That is,
If V> Vd, it is not necessary to perform a downshift, the flag F2 is set to "0" in step S13, and a series of shift determination is ended. However, if V≤Vd, step S13
After setting the flag F2 to "1" in step 12, step S
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 stage is, for example, O / D, the accelerator operation amount Ac increases sharply after the gear shift determination to 3rd is made and before the gear stage is actually switched to 3rd. It becomes "2 ← 3"
If the line exceeds the downshift line, the 2nd shift speed is set. At step S10, the current accelerator operation amount Ac
To downshift vehicle speed V for all downshift lines
d is obtained, and in step S11, the shift down vehicle speed Vd is compared with the current vehicle speed V to make a downshift shift determination.

If step S40 is YES, that is, if automatic engine braking control is being executed, step S41 is executed subsequently to step S40,
It is determined whether the flag F5 is "0". The flag F5 is
When the automatic engine brake control is executed and all the conditions of steps SS1 to SS5 in FIG. 7 are satisfied and the brake pedal is depressed, the value is set to “1” in step SS23 in FIG. 8 and otherwise. It is set to "0" in step SS6 or SS12, and the flag F
If 5 = 0, step S42 is executed, and flag F5
When = 1, step S45 is executed. In step S45 executed when the brake pedal is depressed, a predetermined downshift map for engine braking is searched to obtain the downshift vehicle speed Ved for engine braking. The downshift map during engine braking is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, like the normal downshift map shown by the broken line in FIG. ,
It is easier to downshift because it deviates to the higher vehicle speed side than the normal downshift map. Downshift vehicle speed Ve
d is obtained according to the downshift map during engine braking based on the accelerator operation amount Ac, and in the next step S46, the current vehicle speed V corresponding to the output shaft rotation speed N _O and the downshift vehicle speed Ved are compared. Then, it is determined whether or not the downshift is performed. That is,
If V> Ved, it is not necessary to downshift, and the flag F2 is set to "0" in step S44 to complete the shift determination. However, if V≤Ved, step S4 is performed.
After setting the flag F2 to "1" in step 7, step S4
In step 8, a shift speed lower than the current shift speed is set as the next shift speed. The gears set here are those to which engine braking is applied, and the gears shown in parentheses in FIG. 4 are set in the 2nd or 1st. In this case, even if the current gear stage is, for example, O / D, the vehicle speed V decreases sharply after the gear shift determination to 3rd is made and before the gear shift to 3rd is actually performed. When the "2 ← 3" downshift line is exceeded, the 2nd shift speed is set. In step S45, the downshift vehicle speed Ved for all downshift lines is obtained from the current accelerator operation amount Ac, and in step S46, each downshift vehicle speed Ved is compared with the current vehicle speed V to make a downshift determination. Do it.

In step S42 executed when the brake pedal is not depressed, it is determined whether the 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 braking control, and when the shift output of the downshift is performed, the flag F4 of 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 terminate the shift determination, and if F4 = 1, step S4
Execute 3. In step S43, the next low speed stage where the engine brake acts as the next shift stage, that is, 2nd
Alternatively, in the case of 1st, the gear stage shown in parentheses in FIG. 4 is set.

When the next shift speed is set in step S15, S43 or S48, the shift timing time T1 is set in step S16.
This gear shift timing time T1 is a delay time until the gear shift is actually output after the gear shift judgment is made (step S30), and a plurality of gear shifts are performed in a short time (multiple gear shift). ) And when the accelerator pedal is quickly released to activate the engine braking on a downhill, even if an upshift determination to the O / D gear is made, before the actual upshift is performed. This is provided to prohibit upshifting to the O / D gear when the accelerator operation amount Ac becomes substantially zero.
A fixed value may be set in advance, but different times may be set depending on the type of shift such as upshift or downshift, or downshift in automatic engine braking control. Further, it may be set by a map, a calculation formula, or the like according to the accelerator operation amount Ac at the time of shift determination, the vehicle speed V, the gear stage, and the like.

Next, the flow chart of FIG. 6 for actually changing the shift speed will be described. FIG. 6 is 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, whether the flag F1 is "1", that is, the upshift shift determination is performed. Determine whether or not If the flag F1 is "1", steps S21 and subsequent steps are executed, but if not, 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 for increasing the engine braking force. If the flag F4 is "1", the steps from step S21 are executed. If not, 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 "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, whether or not the accelerator operation amount Ac represented by the accelerator operation amount signal SAc is substantially zero. In consideration of the above, it is determined whether or not it is about 1.5% or less. In step S26, it is determined whether or not the next gear set in step S15 is an O / D gear. 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.
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 even one of the steps S21 to S26 is NO, in step S28, the change of the next shift stage set in step S15 is not performed in step S27, but the determination in steps S21 to S26 is made. In the case of all YES, the next gear is set to "3r" in step S27.
Change to "d". In step S26, it is determined whether or not the next shift speed set in step S15 is O / D. In step S27, the next shift speed is changed from O / D to 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 content measured by the timer Ta is equal to or longer than the shift timing time T1. The above steps S20 and thereafter 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 solenoid S1,
The excitation and non-excitation of S2 and S3 are switched to switch the shift stage of the automatic transmission 78 to the next shift stage set in step S15 or S43 or the 3rd shift stage changed in step S27. After that, the flag F1 is set to "0" and the flag F4 is set to "0" in step S31, and the timer Ta is reset in step S32. The timer Ta has elapsed after the upshift determination was made and the flag F1 was set to "1", or the downshift determination for increasing the engine braking force was made and the flag F4 was set to "1". It measures time.

Here, in step S6, O / D
Even if an upshift determination to the shift stage is made, step S
Until the gear is actually changed at 30
That is, the shift timing time T after the shift determination is made.
If all of the conditions of steps S21 to S26 including the accelerator OFF are satisfied before the lapse of 1, the next shift speed is changed to 3rd, and thus further speedup is disliked on a downhill or the like. When the driver releases the accelerator by the driver, the actual shift to the O / D shift stage is prevented even if the upshift shift determination is made as the accelerator operation amount Ac decreases, and the O / D shift stage is prevented. The reduction in engine braking force due to gear shift to is favorably avoided. For example, when the driver releases the accelerator in the case of traveling for the second time at the state of point A in FIG. 10, “2
Since the accelerator operation amount Ac becomes zero across the "3" upshift line and the "3 → O / D" upshift line, a final shift determination from 2nd to O / D is made in step S6. , In step S15, the O / D shift stage is set as the next shift stage, but if the accelerator operation amount Ac becomes zero before the shift timing time T1 elapses after the "2 → 3" upshift determination is made, "3 → O /
Even if the next shift speed is changed to O / D by crossing the "D" upshift line, the next shift speed is changed to 3rd in step S27, and therefore the upshift to the O / D shift speed is not performed.

Even if the accelerator is turned off once,
If the pedal is depressed again before reaching the shift timing time T1, the determination in step S25 is NO, and in step S28 the next shift stage is set to the O / D set in step S15. When the pedal is depressed, the driver does not need the engine braking force so much, and therefore the driver may upshift to the O / D gear. Even if the determination of step S29 is inserted between steps S20 and S21, the determination of step S21 and subsequent steps is executed based on the operating state when the shift timing time T1 has elapsed, and the shift speed is switched. good.

Further, the accelerator return speed is relatively slow,
Even if the accelerator is not turned off within the shift timing time T1, the shift as set in step S15 is executed, but in this case as well, it is considered that the driver does not need much engine braking force, so O / There is no problem in upshifting to the D gear. In other words,
If the driver needs the engine braking force, he / she should release the accelerator pedal quickly, and if he / she wants to coast or the like, which does not require much engine braking force, he / she should release the accelerator pedal slowly. It's good.

Next, the throttle control of FIGS. 7 to 9 will be described. First, in steps SS1 to SS5 of FIG. 7, the same as steps S21 to S25 regarding the shift range, the traveling pattern, the vehicle speed V, and the accelerator operation amount Ac. If the judgment is made and all the conditions are satisfied, the automatic engine braking control of step SS8 and below is executed,
If any one of them is NO, step SS6 of FIG.
The flag F3, the flag F5, and the flag F7 are each set to "0", and the normal throttle control is performed in step SS7. In the normal throttle control in step SS7, the throttle valve opening degree TA (Ac) is calculated from a predetermined map or a calculation formula based on the accelerator operation amount Ac represented by the accelerator operation amount signal SAc, and the throttle valve opening degree TA is calculated. (Ac) is the target throttle valve opening TA
Set to ^* and the target throttle valve opening TA
^The throttle command signal SQ indicating ^* is output to the throttle control computer 35. The throttle control computer 35 performs throttle control so as to match the actual throttle valve opening θ of the throttle valve 20 with the target throttle valve opening TA ^* represented 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", but this flag F3
Is set to "0" in step SS6, so it is "0" when step SS8 is first executed,
Then, step SS10 is executed to set the vehicle speed V at that time to the target vehicle speed Vm. The flag F3 is set to "1" in step SS14 or SS19 of FIG.
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 and the vehicle speed V at that time are compared to obtain V
If (Vm-Vf), step SS11 and subsequent steps in FIG. 8 are executed, but if V≤ (Vm-Vf), step SS10 is executed again, and after changing the target vehicle speed Vm to the vehicle speed V at that time, step Execute SS11 and below. Considering the fluctuation of the vehicle speed V due to the feedback control of the throttle valve opening θ in steps R4 and R6 of FIG. 9, the constant value Vf is determined to be NO in step SS9 depending on the fluctuation of the vehicle speed V accompanying the throttle control. Although it does not occur, it is determined that the target vehicle speed Vm is changed in step SS10 if the judgment of step SS9 is NO when the vehicle speed V is relatively greatly lowered by the depression operation of the brake.

In step SS11 of FIG. 8, it is judged whether or not the brake pedal is operated based on the brake signal SB. If the brake is OFF, that is, if the pedal is not operated, step SS12 and the following steps are executed. When the person desires further deceleration and depresses the brake, the determination in step SS11 becomes NO, and steps SS22 and SS23 are executed. Step SS2
In No. 2, in order to increase the engine braking force, the target throttle valve opening TA ^{* is set} to 0, and the throttle command signal SQ representing 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 below in FIG. 5 are executed. At the beginning of the automatic engine braking control, that is, in the first cycle in which the accelerator is turned off, the normal brake is turned off.
The judgment of 1 is YES and the step SS14 or SS
In FIG. 19, the flag F3 is set to "1", and in FIG. 5, the steps from step S41 onward during engine braking are executed.

Step SS executed when the brake is OFF
In step 12, the flag F5 is set to "0", and in step SS13, whether or not the flag F1 is "1", that is, the step S
At step 6, it is determined whether or not the upshift is determined. When the flag F1 = 1, the flag F3 is set to "1" in step SS14, and then the normal throttle control similar to that in step SS7 is performed in step SS15. If the upshift gearshift determination is not made, or if the upshift gearshift output is made and the flag F1 is set to "0" in step S31 of FIG. 6, the determination in step SS13 is NO. Then, in step SS16, it is determined whether the flag F6 is "0". The flag F6 is set to "1" in step R11 of FIG. 9 when the downshift is performed to increase the engine braking force. When the flag F6 = 0,
In step SS17, it is determined whether the flag F3 is already "1".

When the flag F3 is not "1" in the first cycle of the automatic engine braking control and the determination in step SS17 is NO, step SS20 is executed after setting the flag F3 to "1" in step SS19. The same normal throttle control as in step SS7 is performed.
When the flag F3 = 1, it is determined in step SS18 whether gear shifting is in progress, for example, whether or not the following expression (1) is satisfied. That is, in step S30 of FIG. 6, the gear shift output is performed and the solenoids S1, S
When the excitation and non-excitation of S2 and S3 are switched, the clutch C and the brake B of the automatic transmission 78 start to slip, and the rotation speed ratio of the turbine rotation speed N _T and the output shaft rotation speed N _O is changed, that is, Since the gear shift ends when the gear ratio i of the current gear stage after the gear shift output substantially matches, the rotational speeds N _T , N _O and the gear ratio i of the current gear stage i.
When the following expression (1) is satisfied, the gear change is not being performed, and when the following expression (1) is not satisfied, the gear change is being performed. Then, if the determination in step SS18 is YES, that is, if the shift is not in progress, the automatic engine brake throttle processing routine in step SS21 is executed, but if the shift is in progress, step SS20 is executed. The above equation (1) is set to satisfy a predetermined range in consideration of detection errors of the rotational speeds N _T and N _O. Also, during downshifts to increase engine braking power,
Since step SS24 and the subsequent steps are executed after step SS16, it is determined in step SS18 whether or not the shift is being substantially performed during the upshift.

[0038]

## EQU1 ## N _T ≈N _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 throttle valve opening θ is feedback-controlled 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 actual throttle valve opening θ represented by the throttle valve opening signal Sθ is smaller than a predetermined judgment value θ1. The determination value θ1 is a small value of about 1.5% or less, and the determination value θ1 can also be determined using an idle signal or the like indicating that the throttle valve opening θ is substantially fully closed. Then, in the case of θ ≧ θ1,
That is, when the engine braking force can be increased by closing the throttle valve opening θ, the timer Tc is reset in step R2, the flag F7 is set to "1" in step R3, and then step R4 is executed. . In step R4, the throttle valve opening TA1 (%) for making the vehicle speed V substantially match the target vehicle speed Vm is calculated according to the calculation formula of the feedback control according to the deviation between the target vehicle speed Vm and the current vehicle speed V.

In the next step R5, based on the current shift speed and the target vehicle speed Vm, the throttle valve opening that can maintain the target vehicle speed Vm in flat ground traveling, that is, the driving force considering the running resistance becomes zero. Throttle valve opening TAm
(%) Is calculated by map interpolation from a previously stored data map 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 of FIG. 11 is obtained by determining the throttle valve opening degree at which the driving force matches the running resistance for each shift speed and vehicle speed, based on the data shown in FIG. 12, which is experimentally obtained in advance. . 12
The data indicates that in the vehicle equipped with the engine having the output characteristics shown in FIG. 13, the gear position of the automatic transmission 78 is O / D.
(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 TAm (%) is flat. The throttle valve opening (angle) at point B, which matches the running resistance on the ground, is about 7.4 °, so if this is converted to 80% of full opening,
(7.4 / 80) × 100 = 9.3. That is,
In the data map of FIG. 11, the vehicle speed is 8 at the O / D shift stage.
The throttle valve opening TA _{45 at} 0 km / h is specifically 9.3%, and thus the throttle valve opening TA _{41 to} TA _{47 at} each vehicle speed in the O / D shift stage can be obtained. ing. For the 3rd gear and the 2nd gear and 1st gear where the engine brake acts, the above O /
As in the case of the D shift stage, the throttle valve opening TA ₃₁
TA ₃₇ , TA _{21 to} TA ₂₇ , TA _{11 to} TA ₁₇ are required. As is clear from the data in FIG. 12, the throttle valve opening degree TAm increases as the vehicle speed increases, and if the vehicle speed is the same, the throttle gear opening TAm increases as the gear ratio increases and the shift speed decreases.

If TA1 <TAm, the throttle valve opening degree TA1 is set to the target throttle valve opening degree TA ^* in step R6, and the target throttle valve opening degree T is set.
By outputting the throttle command signal SQ representing A ^* to the throttle control computer 35, the actual throttle valve opening θ of the throttle valve 20 is changed to the throttle valve opening T.
It is controlled to be A1. These steps R4, R
By repeatedly executing 5 and R6, the throttle valve opening θ is rapidly 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 decreases due to the brake depression operation. Accordingly, the engine braking force with which the vehicle travels at the target vehicle speed Vm changed is obtained. In this embodiment, the vehicle speed V is set to the target vehicle speed Vm.
Since the throttle valve opening θ is feedback-controlled so as to substantially match with the vehicle speed V
The engine braking force is increased / decreased to substantially match the target vehicle speed Vm, and when the gradient changes from a steep gradient to a gentle gradient, it is prevented that the vehicle speed V is lowered against the driver's will due to excessive engine braking. It

On the other hand, the determination in step R5 in the case of TA1 ≧ TAM sets NO, a throttle valve opening TAM in step R7 to the target throttle valve opening degree TA ^*, representing the target throttle valve opening TA ^* By outputting the throttle command signal SQ to the throttle control computer 35, the actual throttle valve opening θ of the throttle valve 20 is controlled to be the throttle valve opening TAm. This is because the engine braking force is increased / decreased so that the vehicle speed V substantially matches the target vehicle speed Vm regardless of the change in the road surface slope as described above, and therefore the throttle valve opening θ Is opened and the vehicle speed V is maintained at the target vehicle speed Vm. However, with such engine brake control, the driver usually thinks that the vehicle speed V decreases on an uphill road, 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 the feedback control. As a result, the target vehicle speed Vm is maintained on the downhill and the flat ground, but the vehicle speed V becomes lower than the target vehicle speed Vm according to the gradient on the uphill, and the traveling control as intended by the driver is performed. Become so.

When the throttle valve 20 is almost fully closed and the engine braking force cannot be increased by the throttle control, the determination at step R1 becomes YES and step R8 is executed, and the flag F7 is "1". Or not. When the flag F7 is not "1",
That is, when step R8 is executed after step R1 in the first cycle in which the accelerator is in the OFF state, steps R2 and thereafter are executed to reset the timer Tc and set the flag F7 to "1". Further, in the next step R9, it is determined whether or not the time content of the timer Tc, that is, the elapsed time after the throttle valve 20 is substantially fully closed exceeds a predetermined delay time T3. At the delay time T3, sufficient engine braking force cannot be obtained even when the throttle valve 20 is substantially fully closed.
~ It is for determining whether or not the throttle valve 20 is maintained in the fully closed state by the feedback control by R6, and a constant value may be set in advance, but the type of shift and the vehicle speed V are used as parameters. It may be set by a data map or fuzzy inference. And
If Tc <T3, the above steps R3 and below are executed. However, if Tc ≧ T3, in the subsequent step R10, the current gear is the lowest speed at which engine braking action can be obtained, that is, in this embodiment. Solenoid S
It is determined whether or not 3 is the excited 1st speed step, and 1
In the case of the st gear, the downshift cannot be performed, so the execution of the steps R3 and thereafter is repeated. 1s gear
When it is other than t, step R11 and the following steps are executed to set the flag F4 instructing the downshift in order to increase the engine braking force to "1" and set the flag F6 representing the throttle control at the time of the downshift to " 1 ”. By setting the flag F4 to "1", as shown in FIG.
Step S43 is started to be executed, and the flag F6
Is set to "1", the step SS2 in FIG.
4 or less will be executed.

In the next step R12, the throttle valve opening TA2 (%) at which substantially the same driving force is obtained before and after the downshift is calculated based on the type of downshift and the current vehicle speed V, for example, as shown in FIG. It is calculated by map interpolation from a predetermined data map as shown in 14. The data map of FIG. 14 is based on the driving force data shown in FIG. 12 that has been experimentally obtained in advance, and the throttle valve 20 at the gear position before the downshift is used.
Is the same as or slightly smaller than the driving force when it is fully closed (acting as a braking force in this case), in other words, the driving force that makes the engine braking force the same or slightly larger, is obtained even after the downshift. Valve opening TA2
(%) Is calculated for each type of shift and vehicle speed. For example, when the vehicle speed is 80 km / h in the O / D gear and the accelerator is off, the driving force is about −300 N as indicated by point C in FIG. 12, so the O / D gear is shifted 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 throttle valve opening degree TA2 is a value of the throttle valve opening degree at which the above-mentioned driving force at 0 km / h, that is, a driving force equal to or slightly smaller than −300 N is obtained. “O / D → 3r in FIG. 14
d ”The throttle valve opening TA2 _{31 to} TA2 _3n during gear shifting is
In this way, the vehicle speed is determined for each of V _{1 to} V _n ,
"3rd → 2nd (S3ON)" Throttle valve opening TA2 _{21 to} TA2 _2n at the time of shifting, and "2nd → 1st (S3ON)
ON) ”Throttle valve opening during gear shifting TA2 _{11 to} TA2 _1n
Also, it is determined in the same manner as above by 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 gear shift, and for the same vehicle speed, the throttle valve opening TA2 is larger in the downshift on the low speed side than in the downshift on the high speed side.

Further, in the subsequent step R13, the 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 gear shift output is performed in step S30 until the throttle valve 20 is opened and controlled, and is on the high speed stage side that is released during the downshift. The engine rotational speed NE and the A / T oil temperature THO were set as parameters in advance so as to increase the engine rotational speed NE in accordance with the timing at which the clutch C and the brake B started 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 draining and supply, and the faster the gear C is output to the clutch C and the brake B on the high speed stage side. Since the delay time until the start of slippage becomes shorter, the throttle valve opening change timing time T2 becomes smaller as the A / T oil temperature THO becomes higher. Further, as the engine speed NE is higher, the delay time until the engine 10 is actually blown up after the throttle valve 20 is opened is controlled. Therefore, the throttle valve opening change timing time T2 is higher as the engine speed NE is higher. It will be a small value.

When the flag F6 is set to "1" in step R11, step SS in FIG.
The determination of 16 is NO, and step SS24 is executed. In step SS24, it is determined whether or not the shift output for the downshift is performed in step S30 and the flag F4 is set to "0" in the next step S31. Until F4 = 0, step SS25 is determined. At T, the timer Tb is reset, and when F4 = 0, steps SS26 and thereafter are executed. By resetting the timer Tb in step SS25, the timer Tb measures the elapsed time when the flag F4 is set to "0", in other words, when the downshift gear shift output is performed, At step SS26, the timer T
It is determined whether or not the timing content of b is equal to or longer than the throttle valve opening change timing time T2. When the content measured by 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 The actual throttle valve opening θ is controlled so as to become the throttle valve opening TA2. Further, in the next step SS28, the gear ratio i and the rotational speeds N _T and N of the current gear stage after the downshift gear shift output is performed.
Based on _O , it is determined from the 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 subsequent cycles, step SS16 and subsequent steps are executed after step SS16.

As described above, in this embodiment, when a downshift is performed while the accelerator is off to increase the engine braking force, the driving force after the downshift is the same as or slightly smaller than the driving force before the downshift. Since the throttle valve 20 is controlled to open up to the throttle valve opening TA2, substantially the same engine braking force as before the downshift is applied even after the downshift, and the shock caused by the rapid increase in the engine braking force is reduced. The riding comfort is improved. In particular, in the present embodiment, by executing steps R4 and below after the downshift,
Throttle valve 2 so that vehicle speed V matches target vehicle speed Vm
Since 0 is feedback controlled, 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, and the driving operation becomes extremely easy. . In this embodiment, the state of traveling 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 side released by the downshift start to slip.
Since the timing for controlling the opening of the throttle valve 20 is determined so that E increases, even during the gear shift process in which the engagement switching of the clutch C and the brake B is performed, the inertia torque of the engine 10 or the like temporarily changes. The increase in braking force is suppressed, the engine speed NE is rapidly increased in combination with the torque transmission from the drive wheel side, the shift time is shortened, and the life of the friction material of the clutch C and the brake B is improved. To do.

FIG. 16 shows a vehicle speed of 55 km / h on an 8% downhill due to the automatic engine braking control of this embodiment.
7 is a time chart showing a change in rotational speed and a change in driving torque of each part when a downshift is performed from the 3rd shift stage to the 2nd shift stage at the time of gear shift, that is, the friction engagement device (clutch C ₂ ) Is about 0.69 sec from the start of slipping until the friction engagement device (brake B ₁ ) on the low speed stage is completely engaged.

The line oil pressure of the oil pressure control circuit 150 is generally controlled according to the throttle valve opening θ, and when the throttle valve 20 is opened and controlled as described above, the line oil pressure is increased. As a result, the engaging hydraulic pressures of the clutch C and the brake B also increase, so that the clutch C and the brake B on the low speed stage side are suddenly completely engaged, and the shift time is further shortened. However, in that case, a large shift shock is likely to occur. Therefore, in this embodiment, when the throttle valve 20 is opened in step SS27, the line oil pressure is controlled to a low oil pressure when the throttle valve 20 is fully closed. ing.

In the present embodiment, the portion of the series of signal processing by the transmission control computer 34 that executes steps S30, S42, S43, R11 corresponds to the shift control means, and steps R4, R6, R12, R1.
3, the part that executes SS27 constitutes the engine output control means together with the throttle control computer 35 and the throttle valve 20.

The transmission control computer 34 also controls the engagement and disengagement of the direct coupling clutch 116 of the torque converter 110 at the same time. In this embodiment, the downshift and the engine output are related to the shift control and the throttle control. If the engine braking force cannot be increased anymore due to the reduction control of
By engaging the direct coupling clutch 116, the engine braking force is increased. Such clutch engagement control is performed, for example, according to the flowchart of FIG. 17, and is repeatedly executed at the same cycle time as the shift control and the throttle control.

In step SC1 of FIG. 17, it is determined whether or not the automatic engine braking control is currently being executed, based on whether or not the flag F3 in the throttle control is "1". If the automatic engine braking control is not being executed, the normal direct coupling clutch control is performed in step SC2. The normal direct coupling clutch control is basically based on the vehicle speed V and the throttle valve opening θ according to a predetermined engagement / disconnection diagram (lockup diagram) of the direct coupling clutch as shown in FIG. 18, for example. It is determined whether the running state of the vehicle is in the disengagement region or the engagement region, and the solenoid S4 is appropriately driven to drive the direct coupling clutch 1
16 is engaged or disengaged. The solid line in FIG. 18 is an engagement determination line from the released state to the engaged state, and the broken line is a release determination line from the engaged state to the released state, and a predetermined hysteresis is given to prevent hunting.

On the other hand, when the automatic engine braking control is being executed, in step SC3, the current gear stage is the lowest speed stage in which engine braking action can be obtained, that is, in this embodiment, as in step R10. Then, it is determined whether or not the solenoid S3 is in the excited first gear. If it is not the first gear, downshifting to increase engine braking is possible.
It is not necessary to engage the direct coupling clutch 116, and step SC4 is executed to bring the direct coupling clutch 116 into the released state. However, in the case of the above-mentioned 1st shift stage, in the next step SC5, the throttle valve opening degree θ is predetermined in order to judge that the engine output is reduced to approximately the minimum in the throttle control. It is determined whether it is smaller than the determination value θ2. The judgment value θ2 is a very small value like the judgment value θ1, and when it is the same as θ1, the judgment value θ2 can be judged by the idle signal. When θ> θ2, it is possible to reduce the engine output and increase the engine braking force by throttle control, so step SC4 is executed. However, if θ ≦ θ2, step SC6 and other steps are performed. It is determined whether or not each of the conditions is satisfied.

First, at step SC6, the vehicle acceleration d
It is determined whether V / dt is zero or more, that is, whether the vehicle speed V is substantially constant or is increasing. When the acceleration dV / dt is negative and the vehicle is in the deceleration state, step SC4 is executed because it is not necessary to increase the engine braking force any more, but if the vehicle is in the constant velocity state or the acceleration state, step SC7 is executed. Do the following: In the acceleration state, the engine braking force is still insufficient, so it is desirable to engage the direct coupling clutch 116 to increase the engine braking force. In the constant velocity state, the traveling state is stable. Even if the direct coupling clutch 116 is engaged, the shock is small. In step SC7, it is determined whether or not the vehicle speed V is equal to or higher than the target vehicle speed Vm. If V <Vm, step SC4 is executed, but if V ≧ Vm, step SC8 is executed. In step SC8, it is determined whether or not the current vehicle speed V is equal to or higher than the release vehicle speed Vcf. If V <Vcf, step SC4 is executed, but if V ≧ Vcf, step SC9 is executed. The release vehicle speed Vcf is
Release determination line (dashed line) in the engagement release diagram of FIG.
In, the vehicle speed is when the throttle valve opening θ is substantially zero. In step SC9, the engine speed NEa when the direct coupling clutch 116 is engaged at the current vehicle speed V and the current shift speed (1st) is calculated from the vehicle speed V and the gear ratio, and the engine speed NEa is overrun by the engine 10. It is determined whether the rotation speed is equal to or lower than the upper limit rotation speed NE2. If NEa> NE2, step SC4
Is executed, but if NEa ≦ NE2, step SC
10 is executed to engage the direct coupling clutch 116.

In addition to the basic conditions of steps SC3 and SC5, the four additional conditions of steps SC6, SC7, SC8, and SC9 indicate whether or not the direct coupling clutch 116 can be safely engaged. The direct coupling clutch 116 is engaged when all the conditions including them are satisfied.
If any one of them is denied,
The direct coupling clutch 116 will not be engaged. In this embodiment, the transmission control computer 3
Of the series of signal processing according to 4, the above-mentioned step SC3
The portion that executes SC5 and SC10 constitutes clutch engagement means together with the hydraulic control circuit 150.

In the present embodiment, the engagement control of the direct coupling clutch 116 is performed even during the execution of the automatic engine braking control as described above, and the engine control is sufficient only by the shift control and the throttle control on a steep downhill. When the force is not obtained and the predetermined engagement condition is satisfied, the direct coupling clutch 116 provided in the torque converter 110 is provided.
Are engaged and the automatic transmission 78 and the engine 10 are directly connected. As a result, the slip loss in the torque converter 110 is removed and the engine braking force is increased by that amount, the control range of the engine braking force that does not require a braking operation is expanded, and the driving operation is further facilitated and expanded. As a result, the feeling of lack of engine braking force is reduced and the driving feeling is improved.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above embodiment, the throttle valve 20
The engine output is increased and decreased by controlling the opening of the engine. However, it is also possible to increase and decrease the engine output by using an engine accessory such as an alternator or by controlling the idle speed control valve 38 to open. it can.

Further, in the above embodiment, the throttle valve opening θ
Although the vehicle controlled by the throttle control computer 35 has been described above, the present invention is also applicable to a vehicle in which the throttle valve 20 is mechanically connected to an accelerator pedal to open and close. The configuration of the automatic transmission 78 and the number of gears can be changed as appropriate.

Further, in the above embodiment, the solenoid S3 is excited so that the engine brake can be applied even at the first gear, but the lowest speed at which the engine brake is applied is 2nd or 3rd. The invention can be applied as well.

Although the throttle valve opening TA2 is set on the basis of the type of shift and the vehicle speed V in the above embodiment, it depends on the operating state of the EGR (exhaust gas recirculation device) and the engine cooling water temperature. The engine output changes due to engine friction torque changes, and due to changes in the oil pump drive torque due to the A / T oil temperature THO, changes in the friction torque of the torque converter 110 and the input shaft 120, changes in auxiliary machinery drive torque such as air conditioners and alternators, etc. Even if the throttle valve opening θ is the same, the torque required for rotating and blowing up the input shaft 120 changes, so the throttle valve opening TA2 is taken into consideration in consideration of these operating states.
Can also be set.

Further, in the above-described embodiment, the throttle valve opening change timing time T2 is set so that the engine rotational speed NE rises almost at the same time when the friction engagement device on the high speed stage side, which is released during the downshift, starts to slide. However, it suffices that it is determined that the engine output increases at least from the start of the slip to the time when the friction engagement device on the low speed stage side is completely engaged. It is sufficient that the engine output increase control is performed so that the driving force before and after the gear shift is substantially equal when the gear is completely engaged, that is, when the gear shift is completed. For example, at the initial stage of gear shifting when the frictional engagement device on the high speed side starts to slide, the throttle valve opening TA2 is added with a predetermined value ΔTA in consideration of inertia of the crankshaft 118, the torque converter 110, and the like. It is also possible to control the opening of the valve 20 or temporarily open the throttle valve 20 largely until the engine speed rises.

Further, in the above-described embodiment, the timer Tb measures the elapsed time with the shift output in step S30 as the measurement start time. However, the determination time such as step R11 is the measurement start time. As a matter of course, the elapsed time may be measured as a matter of course, and the opening control of the throttle valve 20 may be started by detecting a slip of the frictional engagement device on the high speed stage side by a rotation speed sensor, a hydraulic pressure sensor or the like. good.

In the above embodiment, the automatic engine braking control of step SS8 and thereafter is executed on condition that the automatic engine braking pattern is selected by the pattern select switch 70. When the driving pattern of is selected, automatic engine braking control is performed,
The automatic engine braking control may be executed regardless of the type of driving pattern. Of course, the engine brake control switch may be provided independently of the pattern select switch 70.

Further, although the vehicle speed limitation of steps SS3 and SS4 is provided as a condition for performing the automatic engine braking control in the above-mentioned embodiment, such vehicle speed limitation is not always necessary and the range of the vehicle speed limitation is appropriately determined. Other conditions may be added as conditions for performing automatic engine braking control.

Further, in the above embodiment, every time the determination at step SS9 becomes NO as the vehicle speed V decreases, step SS is performed.
10 was executed and the target vehicle speed Vm was sequentially changed according to the vehicle speed V at that time.
It does not matter if S9 is omitted and the target vehicle speed Vm is changed by the vehicle speed V when the brake is released, or the target vehicle speed Vm is sequentially updated based on the vehicle speed V when the brake is ON.

In the above 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. When is changed to 3rd, step S30 may be immediately executed to output the gear shift even before the gear shift timing time T1 is reached.

Further, in the above embodiment, the vehicle speed V when the accelerator is off or when the brake is released is set to be the target vehicle speed Vm as it is, but the target vehicle speed Vm does not have to completely match the vehicle speed V, and the measurement is performed. The target vehicle speed Vm may be set by adding or subtracting a predetermined value to 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.
Although the throttle valve opening θ is feedback-controlled so as to match m, 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 decreasing the throttle valve opening θ by a constant amount ΔTA so that does not exceed the target vehicle speed Vm. Step S
The constant value Vf of S9 is determined in consideration of the variation 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 braking control, such as performing downshift so that the acceleration becomes negative and increasing control of the engine braking force.

Further, in the above-described embodiment, the direct coupling clutch 116 is arranged in the torque converter 110 for amplifying the torque. However, a fluid coupling which does not amplify the torque is used as the fluid coupling, and the fluid coupling is used as the fluid coupling. It may be the case where a direct coupling clutch is provided.

In the above embodiment, step SC3
For basic conditions of SC5, 4 of steps SC6 to SC9
Although the three conditions have been added as additional conditions for determining whether or not the direct coupling clutch 116 can be safely operated, these conditions are not essential in the present invention, and each condition can be changed appropriately. The four conditions may be extracted and used, or other conditions may be added.

Further, in the above embodiment, the direct coupling clutch 11
6 was controlled to be either engaged or disengaged, but in the case where the direct coupling clutch 116 can be slip-engaged by hydraulically controlling the linear solenoid valve or the like, step SC1 , SC3, and when the conditions of SC5 to SC9 are satisfied, the direct coupling clutch 11
Even if 6 is slip-engaged, the effect of the present invention can be obtained.

Further, although the engine control computer 32, the transmission control computer 34, and the throttle control computer 35 are separately configured in the above embodiment, they may be configured by a single computer. It is possible.

Although not illustrated one by one, 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 drawings]

FIG. 1 is a diagram corresponding to a claim 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 that is an embodiment of the present invention.

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

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

FIG. 5 is a flowchart illustrating an operation of determining whether to change a shift speed of the automatic transmission shown in FIG.

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

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

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

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

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

FIG. 11 is an example of a data map used when determining the throttle valve opening degree TAm in step R5 of FIG. 9.

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

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

FIG. 14 is an example of a data map used when determining a throttle valve opening degree TA2 in step R12 of FIG.

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

16] FIG. 16 is a diagram showing an example in which, in the embodiment of FIG.
6 is a time chart showing changes in the rotational speed, driving torque, etc. of each part when a downshift is performed to the d shift stage.

FIG. 17 is a flowchart illustrating an operation of engagement control of a direct coupling clutch in the embodiment of FIG.

18 is an example of an engagement release diagram for a direct coupling clutch used when performing normal direct coupling clutch control in step SC2 of FIG.

[Description of Reference Signs] 10: Engine 20: Throttle valve 34: Transmission control computer 35: Throttle control computer 78: Automatic transmission 110: Torque converter (fluid coupling) 116: Direct coupling clutch 150: Hydraulic control circuit Steps S30, S42 , S43, R11: shift control means Steps SS27, R4, R6, R12, R13: engine output control means Steps SC3, SC5, SC10: clutch engagement means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F16H 61/14 E 8917-3J

Claims (1)

[Claims] 1. An automatic transmission having a plurality of shift speeds, a fluid coupling for transmitting engine output to the automatic transmission through a fluid, and an automatic transmission engine arranged in parallel with the fluid coupling. In a vehicle equipped with a direct coupling clutch, the engine braking force automatic control automatically increases the engine braking force so as to reach a predetermined running state even when the vehicle speed increases even when the accelerator is substantially off. A shift control means for downshifting the automatic transmission to a low speed stage where an engine brake acts when the engine output becomes substantially minimum; and a drive before and after the downshift during the downshift by the shift control means. Engine output control that increases the engine output so that the forces are approximately the same and reduces the engine output after the downshift is completed Means and the shift control means downshifts the automatic transmission to the lowest speed stage on which engine braking acts, and when the engine output is reduced to approximately the minimum by the engine output control means, the direct clutch is closed. An engine braking force automatic control device, comprising: a clutch engagement means for engaging.