JPH05214975A - Engine braking force control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a device that controls the engine braking force when the accelerator is off, in order to obtain an appropriate engine braking force without excess or deficiency depending on the degree of acceleration corresponding to the slope of the downhill. To do. [Structure] When the accelerator changes from an ON state to an OFF state (NO in step SS17), the throttle valve opening TH that regulates the amount of intake air to the engine in step SS20 is driven in the flatland traveling state. By setting the throttle valve opening TH2 at which the force becomes substantially zero, the engine braking force is once adjusted to the control initial value, and thereafter, in step SS21, the throttle valve opening TH is decreased according to the increase of the vehicle speed to reduce the engine braking. The force was made to increase above the control initial value.

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 control device in a vehicle equipped with an automatic transmission, and in particular,
The present invention relates to an improvement in control technology for increasing engine braking when speeding up on a downhill despite the accelerator being off.

[0002]

2. Description of the Related Art Generally, an automatic transmission of a vehicle is designed to change a gear ratio steplessly or without permission based on an accelerator operation amount or a throttle valve opening and a vehicle speed.
FIG. 10 is an example of a shift map (shift condition) of an automatic transmission having four shift stages. The shift stages can be switched based on the accelerator operation amount and the vehicle speed, and the solid line indicates the shift on the upshift side. In the map, the broken line is the shift map on the downshift side. Such a shift map is usually
Even if the accelerator operation amount is zero, that is, it is in the OFF state, upshifting is performed according to the vehicle speed, so even if the accelerator pedal is released on a downhill, if the vehicle speed increases without sufficient engine braking force being obtained. However, there was a problem that the automatic transmission was upshifted and the engine braking force was further reduced. As a countermeasure, accelerator off
An engine braking force control device capable of obtaining a sufficient engine brake by preventing an upshift of a gear when the vehicle speeds up in a state is disclosed in, for example, JP-A-63-308258. Has been done.

[0003]

However, in such a conventional engine braking force control device, a constant engine braking force determined by the gear ratio at that time and the engine output when the throttle is fully closed is provided regardless of the magnitude of the road surface gradient. For example, if the driver releases the accelerator pedal for a slight speed increase while traveling on a downhill with a relatively gentle slope, an excessive engine braking force unintended by the driver may occur. There was a case where a malfunction such as deceleration occurred and the driveability was rather deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain an appropriate engine braking force according to a road surface gradient.

[0005]

In order to achieve such an object, the engine braking force is increased according to the increase in vehicle speed after the vehicle can be driven at a constant speed at the speed when the accelerator is off on a flat ground. According to the present invention, as shown in the claim correspondence diagram of FIG. 1, the accelerator is in an OFF state in a vehicle equipped with an automatic transmission that changes a gear ratio according to a predetermined gear change condition. Is an engine braking force control device for controlling the engine braking force when the following conditions are satisfied: (a) an accelerator operation amount sensor for detecting an accelerator operation amount; (b) a vehicle speed sensor for detecting a vehicle speed; Intake air amount adjusting means for adjusting the intake air amount, and (d) the accelerator operation amount based on an output signal of the accelerator operation amount sensor is equal to or less than a predetermined value which is substantially zero. And the reference intake air amount predetermined with the vehicle speed as a parameter so that the intake air amount can maintain the vehicle speed at the time of the accelerator change in a flat ground traveling state. By controlling the intake air amount adjusting means so that the engine braking force is set to a control initial value when the accelerator changes, and (e) the accelerator operation amount is equal to or less than the predetermined value. By controlling the intake air amount adjusting means so that the intake air amount decreases below the reference intake air amount as the actual vehicle speed detected by the vehicle speed sensor increases in the state where A second control means for increasing the engine braking force above the control initial value.

As the intake air amount adjusting means for adjusting the intake air amount to the engine, an electronically controlled throttle valve, an idle speed control valve or the like is preferably used.

[0007]

In such an engine braking force control device, the accelerator operation amount is detected by the accelerator operation amount sensor and the vehicle speed is detected by the vehicle speed sensor, and first, the accelerator operation amount is substantially zero by the first control means. When it is determined that the intake air amount to the engine has changed from a predetermined value greater than or equal to a predetermined value to a predetermined reference intake air amount that can maintain the vehicle speed at the time of the accelerator change in a flat ground traveling state, The intake air amount adjusting means is controlled so that the engine braking force is set to the control initial value in this control. In other words, if the driver releases the accelerator when he or she dislikes further acceleration on a downhill, if the vehicle is traveling on a flat ground, the engine output should be adjusted once to a driving force state that can maintain the vehicle speed when the accelerator is released. As a result, a sudden increase in engine braking force when the accelerator is turned off can be suppressed. On the other hand, the second control means reduces the intake air amount to the engine below the reference intake air amount as the actual vehicle speed increases,
The engine braking force is increased. That is, when the vehicle speed increases due to the acceleration effect due to the slope of the downhill, the amount of intake air to the engine is reduced according to the increase situation of the vehicle speed, and the engine braking force is appropriately increased. An appropriate amount of engine braking force can be obtained according to the different acceleration rates.

[0008]

As described above, according to the engine braking force control device of the present invention, the engine braking force is appropriately increased in accordance with the degree of speed increase corresponding to the slope of the downhill, so that the driver expects. It is now possible to obtain adequate engine braking force without excess or deficiency on the street, and even if the slope on the downhill is small, excessive engine braking force may act as in the past and the vehicle speed may drop too much. The driving operation of the vehicle with the automatic transmission is further facilitated, for example, by avoiding it favorably.

[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 indicating the intake air amount to the engine control computer 32. Throttle valve 20
Corresponds to intake air amount adjusting means for continuously changing the amount of air taken into the engine 10, and controls the throttle valve opening θ according to the throttle control signal DTH supplied from the throttle control computer 35. In addition, the throttle valve 20 is provided with a throttle position sensor 36, which outputs a throttle valve opening signal Sθ representing the throttle valve opening θ to the engine control computer 32, the transmission control computer 34, and the throttle control. Computer 3
Output to 5. The bypass passage 22 is arranged in parallel with the throttle valve 20, and
Is provided with an idle speed control valve 38. By controlling the opening of the idle speed control valve 38 by the engine control computer 32, the amount of air that bypasses the throttle valve 20 is adjusted. The engine speed during idling is controlled. The fuel injection valve 30 also
The injection timing and injection amount are 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 outputs a signal representing the intake air temperature to the engine control computer 32.

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 rotation phases of the camshaft and the crankshaft. 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 indicating the oxygen concentration to the engine control computer 32. Further, the distributor 50 is provided with a rotation angle sensor 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 the transmission. Output to the 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 includes an OM, an input / output interface circuit, an A / D converter, and the like, and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM. 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
The D signal SO and the accelerator operation amount signal SA indicating 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 that automatically increases engine braking on a downhill road, etc., and also has a power pattern for performing shift control of the automatic transmission 78 based on a shift map that emphasizes power performance and fuel consumption. 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 the shift control is performed according to the emphasized 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 includes a torque converter 110, a first transmission 112, and a second transmission 114, as shown in FIG. 3, for example. The pump impeller of the torque converter 110 is connected to the crankshaft 118 of the engine 10, and the turbine impeller of the torque converter 110 is the input shaft 1.
It is connected to the carrier 122 of the first transmission 112 via 20. The first transmission 112 is configured to include a sun gear 124, a ring gear 126, and a planetary gear device that includes a planetary gear 128 that is rotatably disposed on the carrier 122 and meshes with the sun gear 124 and the ring gear 126. 124 and carrier 1
22 and a clutch C ₀ and a one-way clutch F _0.
Are provided in parallel, and the sun gear 124 and the housing 130
A brake B ₀ is provided between and.

The second transmission 114 is rotatably disposed on the sun gear 132, the pair of ring gears 134 and 136, and the carrier 138 so as to be rotatable on the sun gear 132, the planetary gear 140 meshed with the ring gear 134, and the carrier 142. The planetary gear 1 that is arranged and meshes with the sun gear 132 and the ring gear 136.
And a ring gear 126 of the first transmission 112. 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. Clutch C
₂ is provided, and a brake B ₁ and a one-way clutch F ₁ and a brake B ₂ that are arranged in series are provided in parallel between the sun gear 132 and the housing 130, and between the carrier 138 and the housing 130. A brake B ₃ and a one-way clutch F ₂ are provided in parallel with each other. Further, the ring gear 134 and the carrier 142 are the output shaft 1
46, and its 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 specified, 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. Is becoming 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 column of solenoid means excitation, and the mark “◯” in the column of clutch and brake means engagement. Shift position "D", "S",
“L” is the operating range of the driver's shift lever,
In the "D" range, the shift control is performed in the four stages from 1st to O / D, in the "S" range, the shift control is performed in the three stages from 1st to 3rd, and in the "L" range, 1st and 2nd. The shift control is performed in each stage. The gear ratio (the rotation speed of the input shaft 120 / the rotation speed of the output shaft 146) is 1 s.
It is the largest at t and becomes smaller as it becomes 2nd, 3rd, and O / D, and the gear ratio of 3rd is 1.0. Also,
In the "D" range, the engine brake acts at 3rd and O / D, and at the 1st and 2nd, the engine brake does not work due to the action of the one-way clutches F ₂ and F ₁ , but is shown in parentheses (1st). , (2nd), the brakes B ₃ and B ₁ are engaged by exciting the solenoid S3, and the engine brake operates. The engine brake is adapted to act on the 2nd of the "S" range and the 1st and 2nd of the "L" range. 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 shift stage.

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 rotation speed sensor 82 detects the rotation speed N _T of the turbine impeller of 0, and the rotation speed sensor 82 detects the rotation speed N _O of the output shaft 146. The rotation speed signals representing the rotation 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 which 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 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. In addition, various other signals that represent the operating state of the automobile, such as the steering angle of the steering wheel, the gradient of the road surface, and the exhaust temperature, can be captured and used for engine control, shift control of the automatic transmission 78, and throttle control. It is possible.

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, and the opening and closing timing of the intake and exhaust valves 28, 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 a 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
Of the solenoid S based on the output shaft rotation speed N _{O of the}
By switching the excitation and non-excitation of 1, S2, and S3, the shift stage of the automatic transmission 78 is switched and controlled. The transmission control computer 34 also switches the lockup clutch of the torque converter 110 between full engagement, a slip state, and release by duty-controlling a solenoid (not shown) provided in the hydraulic control circuit 150. In addition, the throttle valve opening θ of the throttle valve 20 is controlled according to the accelerator operation amount Ac, and the throttle valve opening θ is adjusted to control the engine braking force when the accelerator operation amount Ac is zero. Therefore, the 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 according to the throttle command signal SQ.
It is designed to output TH.

The shift control and throttle control by the transmission control computer 34 will be described below in detail 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. It should be noted that the following control is performed when the "D (drive)" range in which shifting is performed in four forward speeds 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 speed, 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 judged 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 shift speed is determined by the output state of the excitation signal for exciting the solenoids S1, S2, S3. Here is now O /
Being in the D shift stage means that the overdrive switch 74 is turned off during traveling in the O / D shift stage, and in this case, the flag F2 is set in step S14.
Is set to "1" and then "3rd" is set as the next gear in step S15. The judgment in step S1 is YE
Even if it is S, if it is not the current O / D gear and the determination in step S2 is NO, it is determined in step S3 whether it is currently the 3rd gear. Currently 3rd instead of step S3
If the determination is NO, or the determination in step S1 is NO
That is, if the O / D gear is permitted, then step S4 is executed. In step S4, it is determined whether or not the current shift speed is the O / D shift speed. If it is not the O / D shift speed, steps S5 and thereafter are executed to determine whether or not an upshift is performed. ..

In step S5, a predetermined upshift map is searched for 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 upshift. That is, V ≦
If it is Vu, it is not necessary to perform an upshift, and in step S8 it is determined whether or not the current gear is 1st. If it is 1st, in step S9 a flag indicating an upshift state when it is "1". A series of shift determination is ended by setting F1 to “0”. However, when V> Vu, the flag F1 is set to “1” in step S7, and then in step S15, the next shift speed is higher than the current shift speed. Set the gear on the gear side. In this case, even if the current shift speed is, for example, 2nd, the accelerator operation amount Ac sharply decreases after the shift determination to 3rd is made and before the shift speed is actually changed to 3rd. And then "3
When the "→ O / D" upshift line is exceeded, the O / D shift speed 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 shift. 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, steps S10 and subsequent steps are 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, and in step S13, the flag F2 indicating the downshift state is set to "0" at the time of "1" to end the series of shift determination, but if V≤Vd In step S12, the flag F2 is set to "1", and then, in step S15, the 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, after the shift determination to 3rd is made, 3r is actually performed.
Before the gear is switched to d, the accelerator operation amount A
When c exceeds the “2 ← 3” downshift line by suddenly increasing, the 2nd shift speed is set. In step S10, the shift-down vehicle speed Vd for all downshift lines is obtained from the current accelerator operation amount Ac, and in step S11, the respective shift-down vehicle speed Vd and the current vehicle speed V are compared to determine the downshift. Do it.

If YES at step S40, that is, if automatic engine braking control is being executed, step S41 is executed after step S40,
It is determined whether the flag F5 is "0". The flag F5 is
When the automatic engine braking control is executed and all the conditions of steps SS1 to SS5 in FIG. 7 are satisfied and the brake pedal is depressed, it is set to “1” in step SS23 in FIG. It is set to "0" in step SS6 or SS12, and the flag F
If 5 = 0, step S42 is executed and the 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, similar to the normal downshift map shown by the broken line in FIG. ,
It is easier to downshift because it is shifted 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 perform a 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 judgment to 3rd is made and before the gear shift to 3rd is actually performed. If 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 R7 of FIG. 9 when the downshift is performed to increase the engine braking force in the automatic engine brake control, and is set to "1" in step S31 of FIG. 6 when the downshift is completed. If F4 = 0, the flag F2 is set to "0" in step S44 to complete the shift determination, and if F4 = 1, step S43 is executed. In step S43, the next low speed stage where the engine brake acts as the next shift stage, that is, 2nd or 1s.
In the case of t, 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.
The gear shift timing time T1 is a delay time from the time when the gear shift is determined to the time when the gear is actually switched, and it is possible to prevent a plurality of gear shifts (multiple gear shifts) from being performed in a short time, and to downhill. When the accelerator pedal is released quickly to activate the engine brake, and when the accelerator operation amount Ac becomes substantially zero before actually performing the upshift, the upshift to the O / D gear is prohibited. A fixed value may be set in advance, but different times may be set according to the type of shift such as upshift or downshift, or downshift in automatic engine braking control. You can 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 gear shift determination, the vehicle speed V, the gear position 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, it is determined whether or not the flag F1 is "1", that is, the upshift shift determination. 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
It is determined whether or not the shift range represented by is "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, and 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 5% or less. In step S26, it is determined whether or not the next gear stage set in step S15 is an O / D gear stage. 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, for example, about 110 km / h. Is set to. Then, if even one of the determinations in steps S21 to S26 is NO, in step S28, the change of the next shift speed set in step S15 is not performed, but step S28 is performed.
If the determinations in 21 to S26 are all YES, the next gear is changed to "3rd" in step S27. The step S26 is to determine whether the next gear set in step S15 is O / D. Even in the cycle after the next gear is changed from O / D to 3rd in step S27, The determination in step S26 is YES.

In step S29, it is determined whether or not the content measured by the timer Ta is not less 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.

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 stage is changed to 3rd, and further speedup is disliked on a downhill or the like. If the driver releases the accelerator pedal, 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 the shift to is favorably avoided. For example, when the driver releases the accelerator in the case of traveling for the second time at the 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. The determination of step S29 may be inserted between steps S20 and S21, and when the shift timing time T1 has elapsed, step S21 and subsequent steps may be executed to switch the shift speed.

Further, the accelerator return speed is relatively slow,
Even when 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 so much engine braking force, so O / There is no problem in upshifting to the D gear. In other words,
When the driver needs the engine braking force, he / she should release the accelerator pedal promptly, and when he / she wants to coast or the like which does not require the engine braking force so much, 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 thereafter is executed,
If any one of them is NO, step SS6 in FIG.
Flag F3 is set to "0" and flag F5
Is set to "0" and normal throttle control is performed in step SS7. The normal throttle control in step SS7 is performed by the accelerator operation amount A indicated by the accelerator operation amount signal SAc.
Based on c, the throttle valve opening TH (Ac) is obtained from a predetermined map or an arithmetic expression, and the throttle valve opening TH (Ac) is set to the target throttle valve opening TH, and the target throttle valve TH 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 the feedback control or the like and the throttle command signal SQ.
To match the target throttle valve opening TH represented by
The 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, flag F is set.
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,
Subsequently, 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,
A 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
> (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 vehicle speed V at that time, and then step Perform SS11 and below. Considering the fluctuation of the vehicle speed V due to the feedback control of the throttle valve opening θ in steps R3 and R5 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, the target vehicle speed Vm is set to be changed in step SS10 when the judgment of step SS9 becomes NO when the vehicle speed V is relatively greatly decreased 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 brake pedal is not operated, step SS12 and the following steps are executed. If the person desires further deceleration and depresses the brake, the determination in step SS11 is NO, and steps SS22 and SS23 are executed. Step SS2
In 2, the target throttle valve opening TH is set to 0 in order to increase the engine braking force, and the throttle command signal SQ representing the target throttle valve opening TH is output to the throttle control computer 35, so that the throttle valve 20 is opened. 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 brake is normally turned off.
Is YES and the result is Step SS14 or SS1.
In FIG. 9, 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, it is determined whether or not the flag F1 is "1".
In 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, in step SS15, if the vehicle is traveling on a flat ground based on the next shift speed and the current vehicle speed V, the shift speed is currently changed. The throttle valve opening degree that can maintain the vehicle speed V, that is, the throttle valve opening degree TH1 (%) at which the driving force in consideration of the running resistance becomes zero is calculated from a pre-stored data map as shown in FIG. 11, for example. Calculated by map interpolation. Then, the throttle valve opening TH1 is set as the target throttle valve opening TH, and the throttle command signal SQ indicating the target throttle valve opening TH is sent to the throttle control computer 35.
Output to the throttle valve 20 so that the actual throttle valve opening θ of the throttle valve 20 becomes the throttle valve opening TH1.

In the data map of FIG. 11, the throttle valve opening at which the driving force matches the running resistance is obtained for each shift speed and vehicle speed based on the data shown in FIG. 12 which has been experimentally obtained in advance. It is a thing. The data of FIG. 12 shows 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), and the gear transmission efficiency is 0.855.
When the tire effective radius is 0.306 m, for example, when the vehicle speed is 80 km / h, the throttle valve opening TH1
(%) Indicates that the throttle valve opening (angle) at point B, which coincides with the running resistance on a flat ground, is about 7.4 °. 4/8
0) × 100 = 9.3. That is, in the data map of FIG. 11, the throttle valve opening TH ₄₅ when the vehicle speed is 80 km / h at the O / D speed is specifically 9.3%.
In this way, the throttle valve opening TH _{41 to} TH _{47 at} each vehicle speed at the O / D gear is obtained. Three
Regarding the second gear shift stage and the first gear shift stage where the rd gear shift stage and the engine brake act, the throttle valve openings TH _{31 to} TH ₃₇ , TH are set in the same manner as in the case of the O / D gear shift stage.
_{21 to} TH ₂₇ and TH _{11 to} TH ₁₇ are required. As is clear from the data in FIG. 12, the throttle valve opening TH1 increases as the vehicle speed increases, and if the vehicle speed remains the same, the throttle gear opening TH1 increases as the gear shift ratio decreases.

On the other hand, 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, step SS13 is executed. The determination is NO, and it is determined in step SS16 whether the flag F6 indicating the throttle change standby state is "0" when it is "1". If the flag F6 is "0", step SS
At 17, it is determined whether the flag F3 is already "1". If flag F3 = 1, step SS18
It is determined whether or not the gear shift is being performed in (1) by, for example, whether or not the following expression (1) is satisfied. That is, in step S30 of FIG. 6, the shift output is performed and the solenoid S1,
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 are expressed by the following equation (1). If it is satisfied, the gear is not being changed, and if the following equation (1) is not satisfied, the gear is being changed. The expression (1) is set to satisfy a predetermined width in consideration of detection errors of the rotation speeds N _T and N _O.

[0039]

## EQU1 ## N _T ≈N _O × i (1)

If the determination in step SS18 is YES, that is, if the gear shift is not in progress, the automatic engine brake throttle processing routine in step SS21 is executed, but if the gear shift is in progress, step SS20 is executed.
Further, the flag F3 is not "1" in the first cycle of the automatic engine braking control, and the determination in step SS17 is N.
In the case of O, the flag F3 is set to "1" in step SS19, and then step SS20 is executed. In step SS20, based on the current gear and the vehicle speed V,
If the vehicle is traveling on a flat ground, the throttle valve opening degree that can maintain the current vehicle speed V, that is, the throttle valve opening degree TH2 (%) at which the driving force in consideration of running resistance becomes zero, is shown in the same manner as the throttle valve opening degree TH1. 11 is calculated by map interpolation from the data map, and the throttle valve opening TH is calculated.
By setting 2 to the target throttle valve opening TH and outputting the throttle command signal SQ representing the target throttle valve opening TH 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 TH2. Engine 10
The intake air amount to the intake air amount is increased / decreased in accordance with the throttle valve opening degree θ to become the intake air amount corresponding to the throttle valve opening degree TH2.

In the automatic engine braking control which is first executed after the accelerator is turned off, step SS1
7. After executing SS19, step SS20 is executed and the throttle valve opening θ is once opened so that the driving force becomes 0. This prevents the engine braking force from becoming excessively large, and it corresponds to the inclination of the downhill. This is to obtain the optimum engine braking force, and the engine braking force is reduced to the control initial value. The intake air amount at this time corresponds to a reference intake air amount that can maintain the vehicle speed at the time when the accelerator is turned off in flatland traveling. Further, the step SS20 is executed during the gear shift to open the throttle valve opening θ so that the driving force becomes 0. In particular, a downshift (downshift of flag F4 = 1) is performed to increase the engine braking force. When performing, the time required to switch the gear speed by rapidly increasing the engine speed NE (shift time)
This is to reduce the vehicle speed, which suppresses an increase in the vehicle speed during gear shifting, in which a sufficient engine braking force cannot be obtained.

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 degree 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 or not the flag F4 is "0". If the flag F4 = 0, the actual throttle valve opening degree θ represented by the throttle valve opening degree signal Sθ is predetermined in step R2. It is determined whether it is smaller than the determined 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.
When θ ≧ θ1, that is, the throttle valve opening θ
When it is possible to increase the engine braking force by closing, the step R3 is executed and the vehicle speed V is made to substantially match the target vehicle speed Vm according to the deviation between the target vehicle speed Vm and the current vehicle speed V. Throttle valve opening TH3
(%) Is calculated according to the feedback control calculation formula.

In the next step R4, based on the current gear position and the target vehicle speed Vm, the throttle valve opening that can maintain the target vehicle speed Vm in flatland traveling, that is, the driving force considering the running resistance becomes zero. Throttle valve opening THm
(%) Is calculated from the data map of FIG. 11 by map interpolation, and it is determined whether the throttle valve opening TH3 is smaller than the throttle valve opening THm. And T
If H3 <THm, in step R5, the throttle valve opening TH3 is set to the target throttle valve opening TH,
By outputting a throttle command signal SQ indicating the target throttle valve opening TH 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 TH3.
By repeatedly executing these steps R3, R4, R5, the throttle valve opening θ is rapidly controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, and the accelerator O
The engine braking force for driving the vehicle at the target vehicle speed Vm at the time of FF or the target vehicle speed Vm changed with the decrease in the vehicle speed V due to the brake depression operation can be obtained. In this embodiment, the throttle valve opening θ is feedback-controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, so that the engine speed is substantially matched with the target vehicle speed Vm regardless of the change in the road surface gradient. When the braking force is increased / decreased and the gradient changes from a steep gradient to a gentle gradient, the vehicle speed V is prevented from being lowered against the driver's intention due to excessive engine braking.

On the other hand, when TH3 ≧ THm, the determination in step R4 is NO, and in step R6 the throttle valve opening THm is set to the target throttle valve opening TH and the throttle command indicating the target throttle valve opening TH is set. By outputting the 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 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, 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 braking control, the driver usually thinks that the vehicle speed V will decrease on an uphill road, and even if traveling on a flat surface. Target vehicle speed Vm
The throttle valve opening THm that can maintain the above is set as the upper limit of the throttle valve opening TH3 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. Will be done.

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 R2 becomes YES, and steps R7 and thereafter are executed. In step R7, the flag F4 instructing the downshift to increase the engine braking force is set to "1", and the flag F6 instructing the throttle change standby is set to "1".
As a result, step S43 of FIG. 5 is executed, and step SS24 and subsequent steps of FIG. 8 are executed. Further, in step R8, based on the gear position after the downshift and the current vehicle speed V, the throttle valve opening that can maintain the current vehicle speed V in flat ground traveling, that is, the driving force in consideration of running resistance is zero. The throttle valve opening TH4 (%) is calculated from the data map of FIG. 11 by map interpolation,
In step R9, the throttle valve opening change timing time T2 is set and the timer Tb is reset.
In the throttle valve opening change timing time T2, the gear shift output is actually performed in accordance with the setting of the downshift in step S43, and the engine speed is set to the above-mentioned throttle in accordance with the timing when the clutch C and the brake B start to slip. The type of shift, the vehicle speed V, the oil temperature of the hydraulic control circuit 150, and the like are predetermined as parameters based on the shift timing time T1 so as to increase corresponding to the valve opening TH4.

When the flag F6 is set to "1" in step R7, step S in FIG.
The determination in S16 is NO, and step SS24 is executed. In step SS24, it is determined whether or not the content of the timer Tb is longer than the throttle valve opening change timing time T2. When the timing time T2 is reached, step S24 is executed.
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.
By outputting the throttle command signal SQ indicating
The actual throttle valve opening θ is the throttle valve opening TH4
Control so that. Then, in step SS26, the flag F6 is set to "0". The change timing of the throttle valve opening degree during the downshift is set so that the engine is blown up in accordance with the timing when the clutch C and the brake B start to slip with the shift output as described above. Is before the change output in step S30, the determination in step SS18 becomes YES in the subsequent cycles and step SS2
1 is executed, but since the flag F4 is "1" until the shift output is made in step S30, the throttle control after step R2 in FIG. 9 is not executed. Further, when the shift output is executed in step S30, the determination in step SS18 is NO, so the throttle control in step SS21 is not executed until the shift is completed. On the other hand, if the change timing of the throttle valve opening is after the shift output in step S30, the determination in step SS18 is NO in the subsequent cycles, and thus the throttle control in step SS21 is similarly performed until the shift is completed. Is never executed.

In the automatic engine braking control of this embodiment, when the accelerator is turned off and the automatic engine braking control is started, first, step S
In S20, the driving force = 0, that is, the throttle valve opening TH capable of maintaining the vehicle speed V at that time in a flat ground traveling state.
The target throttle valve opening TH is set to 2 and the engine braking force is once adjusted to the control initial value, and thereafter, in steps R3 and R5, the throttle valve opening θ is controlled so that the vehicle speed V substantially matches the target vehicle speed Vm. Because
A proper engine braking force with no excess or deficiency can be obtained, and the engine braking force does not become excessive even if the road gradient is relatively gentle. Also, if a downshift is performed to increase the engine braking force, step SS
25 and SS20, the throttle valve opening degree θ is opened up to the throttle valve opening degrees TH4 and TH2 where the driving force becomes 0, and the throttle control is performed by steps R3 and R5 after the completion of the gear shift, so that the engine braking force is downshifted. There is no sudden increase and shock.

In the present embodiment, step SS5 of FIG. 7 and step SS17 of FIG. 8 and its SS in the series of signal processing by the transmission control computer 34.
Step SS20 executed when the determination in 17 is NO
Corresponds to the first control means, and the portion that executes steps R3 and R5 in FIG. 9 constitutes the second control means together with the throttle control computer 35. Further, a rotation speed sensor 82 for detecting the output shaft rotation speed N _O corresponding to the vehicle speed V.
Corresponds to a vehicle speed sensor.

On the other hand, in the present embodiment, in steps R3 and R5, the throttle valve opening θ is controlled so that the vehicle speed V matches the target vehicle speed Vm, and the engine braking force is controlled. Regardless of the change in the vehicle speed V, the engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm, and when the gradient changes from a steep gradient to a gentle gradient, the engine braking is too effective and the vehicle speed V is against the driver's will. Is prevented from falling. In particular, in this embodiment, the throttle valve opening θ is feedback-controlled so that the vehicle speed V substantially matches the target vehicle speed Vm.
Has an advantage that the target vehicle speed Vm can be quickly brought close to, and an appropriate engine braking force can be quickly obtained.

Further, in the present embodiment, when the throttle valve opening TH3 obtained in the above step R3 becomes equal to or larger than the throttle valve opening THm which can maintain the target vehicle speed Vm in the case of traveling on a flat ground, step R6. Since the throttle valve opening THm is set to the target throttle valve opening TH, the vehicle speed V is lowered below the target vehicle speed Vm according to the gradient when there is an uphill after the downhill. The traveling control is performed as intended by the driver who thinks that the vehicle speed V will decrease.

If the driver wishes to further decelerate and depresses the brake during the automatic engine braking control, step SS10 is determined every time the determination in step SS9 becomes NO as the vehicle speed V decreases. Is executed and the target vehicle speed Vm is sequentially changed according to the vehicle speed V at that time. Therefore, when the brake pedal 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, the engine speed is changed based on the new target vehicle speed Vm at the time of releasing the brake. The braking force is controlled. As a result, it is possible to avoid insufficient engine braking force after releasing the brakes.For example, even if you decelerate by depressing the brake before the end of the straight line on the downhill and then release the brake and travel on the curve, accelerate while running the curve. The driving operation is further facilitated.

Further, in this embodiment, when the brake pedal is operated during the automatic engine brake control, the throttle valve 20 is fully closed in step SS22 or step S48, regardless of the throttle control in steps R3 and R5. Since the engine braking force is increased by downshifting in S30, the engine braking control that matches the driver's desire to decelerate is performed, and the driver's foot force is small. The load on the brake is reduced.

In the above embodiment, even if the next gear is changed to 3rd in step S27 of FIG. 6, if the accelerator is depressed before the shift timing time T1, the next gear is changed in step S28. Although it is returned to O / D, as shown in FIG. 14, for example, when the next gear is changed to 3rd in step S27, step S30 may be immediately executed to output gears.

Further, in the above-described embodiment, step SS9 is executed every time the judgment in step SS9 becomes NO as the vehicle speed V decreases.
10 was executed and the target vehicle speed Vm was sequentially changed according to the vehicle speed V at that time. However, as shown in FIG. 15 and FIG. 16, for example, the step SS9 is omitted and the step SS11 and the step SS12 are performed. Alternatively, steps SS27 and SS28 may be provided to change the target vehicle speed Vm according to the vehicle speed V when the brake is released. Also in this case, there is no fear of sudden acceleration due to insufficient engine braking force after releasing the brake, and the same effect as that of the above-described embodiment that the driving operation becomes easier can be obtained.

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

For example, although the engine braking force is controlled by the throttle control and the downshift in the above embodiment, the idle speed control valve 38 may be opened / closed as the intake air amount adjusting means. In addition to controlling the intake air amount, it is also possible to control the engine braking force using an engine auxiliary device such as an alternator, and in a vehicle equipped with a belt type continuously variable transmission, the groove width of the variable pulley, that is, It is also possible to control the engine braking force by changing the gear ratio.

Further, in the above embodiment, the throttle valve opening θ
However, the present invention can be applied to a vehicle in which the throttle valve 20 is mechanically connected to an accelerator pedal to open and close. Ac
Alternatively, the throttle valve opening θ may be used instead of.

Further, in the above embodiment, the automatic engine braking control of step SS8 and the subsequent steps 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. It is of course possible to dispose the engine brake control switch separately from 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, 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 need to be completely matched with the vehicle speed V and is measured. 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 ΔTH, or the vehicle speed V
It is also possible to use other control methods, such as decreasing the throttle valve opening θ by a fixed amount ΔTH so that does not exceed the target vehicle speed Vm. Step S
The constant value Vf of S9 is determined in consideration of the fluctuation of the vehicle speed V accompanying the control of the throttle valve opening θ. It is also possible to use other intake air amount control means for increasing the engine braking force as the vehicle speed V increases, such as controlling the throttle valve opening θ so that the vehicle acceleration becomes negative.

Further, in the above-mentioned embodiment, at the time of downshifting for increasing the engine braking force, step SS
In 20 and SS25, the throttle valve opening degree θ is opened so that the driving force becomes 0 at the gear after the gear shift, and after the gear shift is finished, it is gradually closed by step R3 and the like.
After the shift is completed, the throttle valve opening θ can be controlled so that a braking torque substantially the same as 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 in FIG. 12 and the like with the gear position and the vehicle speed V as parameters, as in the data map in FIG.

Further, in the above-described embodiment, only the upshift to the O / D gear is prohibited in step S27. However, if the engine brake is applied even in the first gear or the second gear, " It is also possible to prohibit the 2 → 3 ”shift and the“ 1 → 2 ”shift. The number of gears of the automatic transmission 78 is also changed as appropriate.

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 carried out 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, an engine, and the like 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 gear shift determination as to whether or not to shift a gear stage of the automatic transmission of 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 of FIG.

11 is an example of a data map used to obtain a throttle valve opening degree at which the driving force in consideration of running resistance is approximately zero from the gear position and the vehicle speed in the throttle control of FIG.

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 a flowchart illustrating another aspect of the shift control for switching the shift stage of the automatic transmission, corresponding to FIG. 6.

FIG. 15 is a flowchart illustrating another aspect regarding control of the throttle valve opening with FIG. 16.

16 is a flowchart illustrating another aspect of controlling the throttle valve opening with FIG.

[Explanation of symbols]

 10: Engine 20: Throttle valve (intake air amount adjusting means) 34: Transmission control computer 35: Throttle control computer 76: Accelerator operation amount sensor 78: Automatic transmission 82: Rotation speed sensor (vehicle speed sensor) V: Vehicle speed step SS5, SS17, SS20: First control means Steps R3, R5: Second control means

Claims (1)

[Claims] 1. An engine braking force control device for controlling an engine braking force when an accelerator is in an OFF state in a vehicle provided with an automatic transmission for changing a gear ratio according to a predetermined gear shifting condition. An accelerator operation amount sensor that detects the amount, a vehicle speed sensor that detects the vehicle speed, an intake air amount adjustment means that adjusts the intake air amount to the engine, and the accelerator operation amount based on the output signal of the accelerator operation amount sensor. The gear ratio and the vehicle speed are set as parameters so that the intake air amount can be maintained at the vehicle speed at the time of the accelerator change when the intake air amount is changed to a value equal to or less than a predetermined value which is substantially zero. By controlling the intake air amount adjusting means so that the reference intake air amount predetermined as First control means for setting the engine braking force to a control initial value, and as the actual vehicle speed detected by the vehicle speed sensor increases in a state where the accelerator operation amount is equal to or less than the predetermined value, A second control unit for increasing the engine braking force above the control initial value by controlling the intake air amount adjusting unit so that the intake air amount becomes smaller than the reference intake air amount. A characteristic engine braking force control device.