JP2921244B2 - Engine brake force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine braking force control device for a vehicle equipped with an automatic transmission,
The present invention relates to an improvement in control technology for increasing engine braking when the vehicle speed is increased in spite of the accelerator OFF state on a downhill.

[0002]

2. Description of the Related Art Generally, an automatic transmission of a vehicle changes a gear ratio stepwise 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, in which the shift stages are switched based on the accelerator operation amount and the vehicle speed. A broken line in the map is a shift map on the downshift side. Such shift maps are usually
Even when the accelerator operation amount is zero, that is, in the OFF state, the upshift is performed according to the vehicle speed. Therefore, even if the accelerator pedal is released on a downhill slope, the vehicle speed increases without obtaining sufficient engine braking force. However, there has been a problem that the automatic transmission is upshifted and the engine braking force is further reduced. As a countermeasure, accelerator off
An engine braking force control device that can obtain sufficient engine braking by preventing an upshift of a gear when a vehicle speeds up in a state is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-308258. Have been.

[0003]

However, in such a conventional engine braking force control system, a constant engine braking force determined by the speed ratio at that time and the engine output when the throttle is fully closed is obtained regardless of the road gradient. For example, if the driver releases the accelerator pedal for a slight increase in speed while traveling on a relatively gentle slope downhill, an excessive engine braking force that the driver does not intend may occur. In some cases, such problems as deceleration due to the action occur, and the drivability may be impaired.

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

[0005]

In order to achieve the above object, on a flat ground, the vehicle can be driven at a constant speed at the speed at which the accelerator is turned off, and then the engine braking force is increased in accordance with the increase in the vehicle speed. According to the present invention, as shown in the claim correspondence diagram of FIG. 1, in a vehicle equipped with an automatic transmission that changes the gear ratio according to a predetermined gear condition, the accelerator is turned off. An engine brake force control device that controls the engine brake force when the vehicle is in the state of (a) an accelerator operation amount sensor that detects an accelerator operation amount; (b) a vehicle speed sensor that detects a vehicle speed; (D) maintaining a constant vehicle speed while driving on flat ground
The vehicle speed and the gear ratio are used as parameters so that
Storage means for storing a predetermined reference intake air amount
When, along with determining that it has changed to the following from (e) the accelerator operation amount based on an output signal of the accelerator operation amount sensor is more than a predetermined value of approximately zero, flat ground
It can maintain the vehicle speed when the accelerator changes during running
The reference intake air amount to be
It is obtained from the storage means based on the gear ratio, and its reference suction
By controlling the intake air quantity adjusting means so that the air amount, a first control means for setting the control initial value of the engine braking force at the time of acceleration changes, (f) the accelerator operation amount is less than the predetermined value And 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 of And a second control means for increasing the engine braking force from 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. 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 or more to a predetermined reference value or less, a predetermined reference intake air amount and 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. Thus, 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 on a downhill and hates further acceleration, the engine output must be temporarily adjusted to a driving force state that can maintain the vehicle speed at the time of releasing the accelerator when traveling on flat ground. This suppresses a sudden increase in the engine braking force when the accelerator is turned off. On the other hand, by the second control means, the intake air amount to the engine is reduced from 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 speed increase effect due to the slope of the downhill, the amount of intake air to the engine is reduced according to the increasing condition of the vehicle speed, and the engine braking force is appropriately increased. An appropriate amount of engine braking force can be obtained according to different degrees of speed increase.

[0008]

As described above, according to the engine braking force control apparatus of the present invention, the engine braking force can be appropriately increased in accordance with the degree of speed increase corresponding to the gradient of the downhill, so that the driver expects. It is possible to obtain an appropriate engine braking force without excess or deficiency on the street, and even if the slope of the downhill is small, the excessive engine braking force acts as in the past and the vehicle speed decreases too much Driving operation of the vehicle with the automatic transmission is further facilitated, for example, it is avoided well.

[0009]

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

Referring to FIG. 2, in a combustion chamber 12 of a 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 sucked in through the intake valve 28,
A fuel gas injected from a fuel injection valve 30 provided in the intake manifold 26 is mixed with the air. The air flow meter 16 measures the amount of intake air, and outputs a signal indicating the amount of intake air to the computer 32 for engine control. Throttle valve 20
Is equivalent to intake air amount adjusting means for continuously changing the amount of air taken into the engine 10. The throttle valve opening θ is controlled in accordance with a throttle control signal DTH supplied from a throttle control computer 35. 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
5 is output. The bypass passage 22 is disposed in parallel with the throttle valve 20 and has a bypass passage 22.
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 flowing bypassing 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 for measuring the temperature of the intake air is provided upstream of the air flow meter 16, and outputs a signal indicating 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 a spark plug 46. The spark plug 46 generates an ignition spark by a high voltage supplied from an igniter 48 controlled by an engine control computer 32 via a distributor 50. The crankshaft is rotated by causing the mixed gas in the combustion chamber 12 to explode and move the piston 44 up and down. The intake valve 28 and the exhaust valve 42 are opened and closed by a cam shaft that is driven to rotate in synchronization with the rotation of the crankshaft, and is controlled by a variable valve timing mechanism (not shown) controlled by the engine control computer 32. The opening and closing timing is adjusted by changing the rotational phase of the camshaft and the crankshaft. The exhaust gas burned in the combustion chamber 12 is supplied from the exhaust valve 42 to the exhaust manifold 5.
4. The gas is discharged to the atmosphere via the exhaust passage 56 and the catalyst device 58. The engine 10 is provided with a water temperature sensor 60 that measures the temperature of the engine cooling water. The water temperature sensor 60 outputs a signal representing the temperature of the engine cooling water to the computer 32 for controlling the engine.
4 is an oxygen sensor 62 for detecting the oxygen concentration in the exhaust gas.
And outputs a signal indicating the oxygen concentration to the computer 32 for engine control. The distributor 50 is provided with a rotation angle sensor that generates a pulse in synchronization with the rotation of the crankshaft, and outputs a pulse signal, that is, an engine rotation speed signal SNE representing the engine rotation speed NE, to the engine control computer 32 and the transmission. Output to the control computer 34.

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

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

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

[0015] The clutch C ₀ -C ₂ and the brake B
_{0 to} B ₃ (hereinafter, unless otherwise specified, the clutch C,
The brake B) is a hydraulic friction engagement device that is controlled to be engaged by a hydraulic actuator such as a multi-plate clutch or a band brake so that hydraulic oil is supplied from a hydraulic control circuit 150 to the hydraulic actuator. Has become. The hydraulic control circuit 150 is provided with a number of switching valves and the like, and the solenoids S1, S2, and S3 are switched between energized and de-energized in accordance with signals from the transmission control computer 34, thereby switching the hydraulic circuit. The engagement of the clutch C and the brake B is selectively controlled, and one of the four forward speeds is established, as shown in FIG. In FIG. 4, the mark “○” in the column of solenoid means excitation, and the mark “○” in the column of clutch and brake means engagement. "D", "S",
"L" is the operating range of the shift lever in the driver's seat,
In the “D” range, shift control is performed in four stages from 1st to O / D, in the “S” range, shift control is performed in three stages from 1st to 3rd, and in the “L” range, two shifts of 1st and 2nd are performed. The shift control is performed at the gear. 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 decreases as 2nd, 3rd, O / D, and the speed ratio at 3rd is 1.0. Also,
The "D" range, the engine braking acts in 3rd and O / D, although not effective engine braking under the action of 1st and the 2nd one-way clutch F _2, F _1, is shown in parentheses (1st) , (2nd), when the solenoid S3 is excited, the brakes B ₃ and B ₁ are engaged, and the engine brake operates. The engine brake also operates at the 2nd in the "S" range and the 1st and 2nd in the "L" range. Although not shown, when the shift lever is operated to the “R” range, the manual shift valve of the hydraulic control circuit 150 is switched to establish the reverse gear.

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

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

The engine control computer 32 calculates the intake air amount, the throttle valve opening θ, the engine speed NE, the cooling water temperature of the engine 10, the intake air temperature, the oxygen concentration in the exhaust passage 56, and the accelerator operation. Amount Ac
In accordance with, for example, the fuel injection valve 3 based on a data map or an arithmetic expression determined in advance to reduce fuel consumption and harmful exhaust gas while securing necessary engine output,
It controls the fuel gas injection amount and injection timing by 0, the ignition timing by the igniter 48, the idle speed by the idle speed control valve 38, and the opening and closing timing of the intake and exhaust valves 28 and 42 by the variable valve timing mechanism. The transmission control computer 34 controls the throttle valve opening θ, the engine speed NE, the selection pattern represented by the pattern signal SP, the presence / absence of the brake operation represented by the brake signal SB, and the O / D shift speed represented by the O / D signal SO. Whether or not a shift can be performed, accelerator operation amount Ac, automatic transmission 78
Based like the output shaft rotation speed N _O of the solenoid S
By switching between excitation and non-excitation of S1, S2, and S3, the shift speed of the automatic transmission 78 is switched. The transmission control computer 34 also switches between a completely engaged state, a slipped state and a released state by duty-controlling a solenoid (not shown) provided in the hydraulic control circuit 150 also for the lock-up clutch of the torque converter 110. In addition, the throttle valve opening θ of the throttle valve 20 is controlled in accordance with the accelerator operation amount Ac, or when the accelerator operation amount Ac is zero, the throttle valve opening θ is adjusted to control the engine braking force. For this purpose, a throttle command signal SQ is output to the throttle control computer 35. Throttle control computer 35
Is basically a throttle control signal D for controlling the throttle valve opening θ in accordance with the throttle command signal SQ.
TH is output.

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

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

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

In step S5, a predetermined upshift map is searched to determine an upshift vehicle speed Vu. The upshift map is predetermined for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, as indicated by the solid line in FIG. 10. As the accelerator operation amount Ac decreases, the vehicle speed V increases. It is designed to upshift to the high speed stage. Upshift vehicle speed Vu
It is determined according to the upshift map based on the accelerator operation amount Ac, at the next step S6, the current vehicle speed V and the shift-up vehicle speed Vu that corresponds to the output shaft rotational speed N _O of the rotational speed signal SN _O represents And compare
It is determined whether to perform an upshift. That is, V ≦
If it is Vu, it is not necessary to perform an upshift. In step S8, it is determined whether or not the current shift stage is 1st. If it is 1st, in step S9, a flag indicating an upshift state when "1" is set in step S9. F1 is set to “0”, and a series of shift determinations is ended. If 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 for the second gear. In this case, even if the current gear position is, for example, 2nd, the accelerator operation amount Ac sharply decreases before the gear position is switched to 3rd after the shift determination to 3rd is made. And "3
If the "> O / D" upshift line is exceeded, the O / D shift speed is set. In step S5, the upshift vehicle speeds Vu for all the upshift lines are obtained from the current accelerator operation amount Ac. In step S6, the respective upshift vehicle speeds Vu and the current vehicle speed V are compared to determine the upshift speed change. Do it.

If the determination in step S3 is YES,
If the determination in step S4 is YES, or
If the determination in step 8 is NO, step S10 and subsequent steps are executed to determine whether to perform downshifting. Step S
At 10, a predetermined downshift map is searched to determine a downshift vehicle speed Vd. The downshift map is determined in advance for each type of shift based on the accelerator operation amount Ac and the vehicle speed V, as indicated by the broken line in FIG. 10. As the accelerator operation amount Ac increases, the vehicle speed V decreases. The gear shifts down to the lower gear. The shift-down vehicle speed Vd is determined by the accelerator operation amount A
determined according to downshift map based on the c, at the next step S11, it compares the current vehicle speed V and the downshift vehicle speed Vd corresponding to the output shaft rotational speed N _O, determines whether to perform a downshift I do. That is,
If V> Vd, there is no need to perform a downshift, and in step S13, a flag F2 indicating a downshift state is set to "0" when "1", and a series of shift determinations is terminated. In step S12, the flag F2 is set to "1", and then, in step S15, a shift speed lower than the current shift speed is set as the next shift speed. In this case, even if the current gear position is, for example, O / D, after the shift determination to 3rd is made,
accelerator operation amount A before the gear is switched to d.
If c exceeds the “2 ← 3” downshift line due to a sudden increase in c, the second shift speed is set. In step S10, the downshift vehicle speeds Vd for all the downshift lines are obtained from the current accelerator operation amount Ac. In step S11, each downshift vehicle speed Vd is compared with the current vehicle speed V to determine the downshift shift. Do it.

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

In step S42 executed when the brake is not depressed, it is determined whether or not a flag F4 is "1". The flag F4 is set to "1" in step R7 in FIG. 9 when downshifting is performed to increase the engine braking force in the automatic engine brake control, and when the downshift is completed, "1" is set in step S31 in FIG. If F4 = 0, the flag F2 is set to "0" in step S44 to end the shift determination, and if F4 = 1, step S43 is executed. In step S43, the next low gear at which the engine brake acts as the next gear, that is, 2nd or 1s
In the case of t, the gear position shown in parentheses in FIG. 4 is set.

When the next gear is set in step S15, S43 or S48, the gear shift timing time T1 is set in step S16.
The shift timing time T1 is a delay time from when the shift determination is made to when the shift speed is actually switched, and it is possible to prevent a plurality of shifts from being performed in a short time (multiple shifts), and to perform a downhill slope. When the accelerator pedal is quickly released to apply the engine brake and the accelerator operation amount Ac becomes substantially zero before actually performing the upshift, the upshift to the O / D gear is prohibited. Although a fixed value may be set in advance, different times are set according to the type of shift such as upshift, downshift, or downshift in automatic engine brake control. You may do it. Further, it may be set by a map, an arithmetic expression, or the like according to the accelerator operation amount Ac at the time of the shift determination, the vehicle speed V, the shift speed, and the like.

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

In step S21, the shift range signal SR
Is determined to be "D (drive)", and in step S22, the traveling pattern represented by the pattern signal SP is determined to be "automatic engine braking pattern".
Determining whether a determines whether larger than the lower limit vehicle speed V1 of the vehicle speed V is preset to correspond to the output shaft rotation speed N _O representing the rotational speed signal SN _O In step S23, in step S24 It is determined whether or not the vehicle speed V is equal to or lower than a predetermined upper limit vehicle speed V2. In step S25, the accelerator is turned off, that is, the accelerator operation amount Ac indicated by the accelerator operation amount signal SAc is substantially zero, specifically, a detection error. In consideration of the above, it is determined whether or not the speed is about 5% or less. In step S26, it is determined whether or not the next shift speed set in step S15 is the O / D shift speed. The lower limit vehicle speed V1 and the upper limit vehicle speed V2 define a vehicle speed range in which special control for engine braking is performed. The lower limit vehicle speed V1 is set to, for example, about 20 km / h, and the upper limit vehicle speed V2 is set to, for example, about 110 km / h. Is set to If at least one of the determinations in steps S21 to S26 is NO, in step S28, the change of the next gear set in step S15 is not performed.
If all of the determinations in S21 to S26 are YES, the next shift speed is changed to "3rd" in step S27. The step S26 determines whether or not 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 counted time of the timer Ta is equal to or longer than the shift timing time T1. Step S20 and subsequent steps are repeated until the shift timing time T1 is reached. When the shift timing time T1 is reached, step S30 is executed, and the solenoids S1 and S1 are executed.
By switching between excitation and non-excitation of S2 and S3, the gear position of the automatic transmission 78 is switched to the next gear position set in step S15 or S43 or the 3rd gear position changed in step S27. After that, the flag F1 is set to "0" in step S31, the flag F4 is set to "0", and the timer Ta is reset in step S32.

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

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

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

Next, the throttle control in FIGS. 7 to 9 will be described. First, in steps SS1 to SS5 in FIG. 7, the shift range, the running pattern, the vehicle speed V, and the accelerator operation amount Ac are the same as those in steps S21 to S25. When the judgment is made and all the conditions are satisfied, the automatic engine brake control in step SS8 and thereafter is executed.
If any one is NO, step SS6 in FIG.
In step F3, the flag F3 is set to "0"
Is set to "0", and normal throttle control is performed in step SS7. In the normal throttle control in step SS7, the accelerator operation amount A indicated by the accelerator operation amount signal SAc
c, the throttle valve opening TH (Ac) is obtained from a predetermined map or an arithmetic expression, the throttle valve opening TH (Ac) is set to the target throttle valve opening TH, and the target throttle valve TH is set. A throttle command signal SQ indicating the opening TH is output to the throttle control computer 35. Throttle control computer 35
Indicates the actual throttle valve opening θ of the throttle valve 20 by feedback control or the like.
To match the target throttle valve opening TH represented by
A throttle control signal DTH is output to the throttle valve 20.

In step SS8, which is executed when all the conditions in steps SS1 to SS5 are satisfied, the flag F
It is determined whether or not 3 is “1”.
Is set to “0” in step SS6, and is “0” when step SS8 is first executed,
Subsequently, step SS10 is executed, and the vehicle speed V at that time is set to the target vehicle speed Vm. Since the flag F3 is set to “1” in step SS14 or SS19 in FIG. 8,
In the subsequent cycles, the determination in step SS8 is YES, and step SS9 is executed. In step SS9,
The vehicle speed (Vm-Vf) obtained by subtracting a predetermined constant value Vf from the target vehicle speed Vm is compared with the vehicle speed V at that time.
If (Vm-Vf), step SS11 and subsequent steps in FIG. 8 are executed, but if V ≦ (Vm-Vf), step SS10 is executed again, and the target vehicle speed Vm is changed to the current vehicle speed V. Execute SS11 and below. The constant value Vf is determined by considering the variation of the vehicle speed V due to the feedback control of the throttle valve opening θ in steps R3 and R5 in FIG. However, if the vehicle speed V decreases relatively greatly due to the operation of depressing the brake, the determination in step SS9 is NO and the target vehicle speed Vm is changed in step SS10.

In step SS11 of FIG. 8, it is determined whether or not the brake is depressed based on the brake signal SB. If the brake is off, that is, if the depressing operation is not performed, steps SS12 and subsequent steps are executed. If the user steps on the brake to further decelerate, the determination in step SS11 is NO, and steps SS22 and SS23 are executed. Step SS2
In step 2, the target throttle valve opening TH is set to 0 in order to increase the engine braking force, and a throttle command signal SQ indicating the target throttle valve opening TH is output to the throttle control computer 35, thereby turning the throttle valve 20 on. Completely closed. Further, in step SS23, the flag F5 is set to "1", so that steps S45 and subsequent steps in FIG. 5 are executed. At the beginning of the automatic engine brake control, that is, in the first cycle in which the accelerator is turned off, the brake is normally turned off.
Is YES and step SS14 or SS1
In step 9, the flag F3 is set to "1", and in FIG. 5, the steps of step S41 and subsequent steps during engine braking are executed.

Step SS executed when brake is off
In step 12, the flag F5 is set to "0", and in step SS13, it is determined whether or not the flag F1 is "1".
At 6, it is determined whether or not an upshift has been determined. If the flag F1 = 1, the flag F3 is set to "1" in step SS14, and in step SS15, if the vehicle is traveling on a flat ground based on the next gear position and the current vehicle speed V, the current gear position is changed even after the gear position is switched. The throttle valve opening that can maintain the vehicle speed V, that is, the throttle valve opening TH1 (%) at which the driving force in consideration of the running resistance becomes zero is obtained from a data map stored in advance as shown in FIG. 11, for example. Calculated by map interpolation. Then, the throttle valve opening TH1 is set as a target throttle valve opening TH, and a throttle command signal SQ representing the target throttle valve opening TH is transmitted to a throttle control computer 35.
Is controlled such that the actual throttle valve opening θ of the throttle valve 20 becomes the throttle valve opening TH1.

In the data map shown in FIG. 11, the throttle valve opening at which the driving force coincides with the running resistance is obtained for each gear position and vehicle speed based on data experimentally obtained as shown in FIG. Things. The data in FIG. 12 shows that, in a vehicle equipped with an 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), the gear transmission efficiency is 0.855,
Throttle valve opening TH1 when tire effective radius is 0.306 m, for example, when vehicle speed is 80 km / h
Since the throttle valve opening (angle) at point B, which corresponds to the running resistance on a flat ground, is approximately 7.4 °, this is converted into a percentage with respect to 80% of the fully open state. 4/8
0) × 100 = 9.3. That is, in the data map of FIG. 11, the throttle valve opening TH ₄₅ at the vehicle speed of 80 km / h at the O / D shift speed is specifically 9.3%.
, And the throttle valve opening TH ₄₁ to TH ₄₇ of the vehicle speed in this way O / D gear stage is sought. 3
Regarding the rd shift speed and the 2nd shift speed and the 1st shift speed where the engine brake operates, the throttle valve openings TH _{31 to} TH ₃₇ and TH ₃₇ are set in the same manner as in the case of the O / D shift speed.
_{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. At the same vehicle speed, the throttle valve opening TH1 increases as the speed ratio increases and the speed decreases.

On the other hand, when the upshift shift determination is not made, or when the upshift shift output is made and the flag F1 is set to "0" in step S31 in FIG. 6, the process proceeds to step SS13. The determination is NO, and in step SS16, it is determined whether or not the flag F6 indicating the throttle change standby state when "1" is "0". If the flag F6 is "0", the process proceeds to step SS
At 17, it is determined whether or not the flag F3 is already "1". If the flag F3 = 1, step SS18
In the above, it is determined whether or not a shift is being performed, for example, based on whether or not the following equation (1) is satisfied. That is, the shift output is made in step S30 in FIG.
S2, S3 excitation and de-energized is switched, begin cause slipping clutches C and brakes B of the automatic transmission 78, after the rotation speed ratio of the turbine speed N _T and the output shaft rotation speed N _O is shifting, i.e. for shifting by substantially coincides with the gear ratio i of the current speed after the shift output ends, the rotational speed N _T of it such as, N _O, and the speed ratio i is the formula of the current gear position (the 1) If it satisfies, it is not shifting, and if it does not satisfy the following equation (1), it is shifting. Incidentally, according equation (1), the rotational speed N _T, taking into account the detection error of N _O are determined so as to satisfy with a predetermined width.

[0039]

N _T ＮN _O × i (1)

If the determination in step SS18 is YES, that is, if the gear is not being shifted, the automatic engine brake throttle processing routine of step SS21 is executed. If the gear is being shifted, step SS20 is executed.
Also, in the first cycle of the automatic engine brake control, the flag F3 is not "1", and the determination in step SS17 is N
In the case of O, the flag F3 is set to "1" in step SS19, and then step SS20 is executed. In step SS20, based on the current gear position and the vehicle speed V,
Similar to the throttle valve opening TH1, the throttle valve opening TH2 (%) at which the current vehicle speed V can be maintained when the vehicle is traveling on a flat road, that is, the throttle valve opening at which the driving force in consideration of the running resistance becomes zero is calculated. 11 by a map interpolation, and the throttle valve opening TH
2 is set to the target throttle valve opening TH, and a throttle command signal SQ indicating the target throttle valve opening TH is output to the throttle control computer 35.
The throttle valve 20 is controlled so that the actual throttle valve opening θ becomes the throttle valve opening TH2. Engine 10
Is increased or decreased according to the throttle valve opening θ, and is set to an intake air amount corresponding to the throttle valve opening TH2.

In the automatic engine brake control executed first when the accelerator is turned off, step SS1
7, SS19, and executing step SS20 to open the throttle valve opening θ once so that the driving force becomes 0 prevents the engine braking force from becoming excessive, and responds to the inclination of the downhill. This is to obtain an optimal 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 traveling on flat ground. In addition, opening the throttle valve opening θ so that the driving force is set to 0 by executing step SS20 during the gear shifting is performed particularly by downshifting (downshifting with the flag F4 = 1) in order to increase the engine braking force. When performing, the time required for shifting the gear position by rapidly increasing the engine rotational speed NE (shift time)
This suppresses an increase in the vehicle speed during gear shifting during 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 feedback control of the throttle valve opening θ is performed so as to coincide with each other, and is specifically executed according to the flowchart of FIG. In step R1 of FIG. 9, it is determined whether or not the flag F4 is "0". If the flag F4 = 0, the actual throttle valve opening .theta. Represented by the throttle valve opening signal S.theta. 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
If it is possible to increase the engine braking force by closing the vehicle, step R3 is executed to make the vehicle speed V substantially equal to the target vehicle speed Vm in accordance with the deviation between the target vehicle speed Vm and the current vehicle speed V. Throttle valve opening TH3
(%) Is calculated according to an arithmetic expression of feedback control.

In the next step R4, based on the current gear position and the target vehicle speed Vm, the throttle valve opening capable of maintaining the target vehicle speed Vm when traveling on flat ground, that is, the driving force in consideration of the running resistance becomes zero. Throttle valve opening THm
(%) Is calculated from the data map of FIG. 11 by map interpolation, and it is determined whether or not the throttle valve opening TH3 is smaller than the throttle valve opening THm. And T
If H3 <THm, the throttle valve opening TH3 is set to the target throttle valve opening TH in step R5,
By outputting a throttle command signal SQ indicating the target throttle valve opening TH to the throttle control computer 35, control is performed so that the actual throttle valve opening θ of the throttle valve 20 becomes the throttle valve opening TH3.
By repeatedly executing these steps R3, R4, and R5, the throttle valve opening θ is quickly controlled so that the vehicle speed V substantially matches the target vehicle speed Vm.
The engine braking force at which the vehicle travels at the target vehicle speed Vm at the time of the FF or at the target vehicle speed Vm changed as the vehicle speed V decreases due to the brake depression operation is obtained. In this embodiment, since the throttle valve opening θ is feedback-controlled so that the vehicle speed V substantially matches the target vehicle speed Vm, the engine is controlled so that the vehicle speed V substantially matches the target vehicle speed Vm irrespective of a change in the road surface gradient. When the braking force is increased or decreased to change from a steep gradient to a gentle gradient, the vehicle speed V is prevented from being reduced against the driver's intention due to excessive application of the engine brake.

On the other hand, if TH3 ≧ THm, the determination in step R4 is NO, and in step R6, the throttle valve opening THm is set to the target throttle valve opening TH, and a throttle command representing the target throttle valve opening TH is set. By outputting the signal SQ to the throttle control computer 35, the throttle valve 20 is controlled so that the actual throttle valve opening θ becomes the throttle valve opening THm. This is because the engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm regardless of the change in the road surface gradient as described above. Is opened and the vehicle speed V is maintained at the target vehicle speed Vm. However, in such an engine brake control, it is normal that the driver thinks that the vehicle speed V decreases on an uphill slope, and the vehicle is driven on a flat ground. Target vehicle speed Vm
Is set as the upper limit of the throttle valve opening TH3 by feedback control. As a result, the target vehicle speed Vm is maintained on a downhill or a flat ground, but on an uphill, the vehicle speed V becomes lower than the target vehicle speed Vm in accordance with the gradient, and the traveling control as intended by the driver is performed. Will be done.

When the throttle valve 20 is substantially fully closed and the engine braking force cannot be increased by the above throttle control, the determination in step R2 becomes YES, and step R7 and subsequent steps are executed. In step R7, the flag F4 for instructing a downshift to increase the engine braking force is set to "1", and the flag F6 for instructing to wait for a throttle change is set to "1".
As a result, step S43 in FIG. 5 is executed, and steps SS24 and subsequent steps in FIG. 8 are executed. In step R8, based on the gear position after the downshift and the current vehicle speed V, the throttle valve opening capable of maintaining the current vehicle speed V when traveling on flat ground, that is, the driving force in consideration of the running resistance becomes zero. The throttle valve opening TH4 (%) is calculated from the data map of FIG.
In step R9, the throttle valve opening change timing T2 is set, and the timer Tb is reset.
The throttle valve opening change timing time T2 corresponds to the timing at which the shift output is actually performed in accordance with the setting of the downshift in step S43, and the engine speed is adjusted to the timing at which 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 in accordance with the valve opening TH4.

When the flag F6 is set to "1" in the above step R7, in the subsequent cycle, the 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 time counted by the timer Tb is equal to or longer than the throttle valve opening change timing time T2.
In S25, the throttle valve opening TH4 is set to the target throttle valve opening TH, and the target throttle valve opening TH is set.
Is output to the throttle control computer 35, whereby the throttle valve 20 is output.
The actual throttle valve opening θ is equal to the throttle valve opening TH4
Is controlled so that Then, in step SS26, the flag F6 is set to "0". The change timing of the throttle valve opening at the time of the downshift is determined so that the engine blows up in accordance with the timing at which the clutch C or the brake B starts to slip according to the shift output as described above. Is earlier than the change output in step S30, the determination in step SS18 becomes YES in the subsequent cycle, and the flow advances to step SS2.
1 is executed, but until the gearshift output is performed in step S30, the flag F4 is "1", so that the throttle control in step R2 and subsequent steps in FIG. 9 is not performed. Further, when the shift output is executed in step S30, the determination in step SS18 is NO, so that 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 later than the shift output in step S30, the determination in step SS18 will be NO in the subsequent cycle, so the throttle control in step SS21 will be continued until the shift is completed. Will not be executed.

Here, in the automatic engine brake control of the present embodiment, when the accelerator is turned off and the automatic engine brake control is started, first, at step S
In S20, the throttle valve opening TH that can maintain the vehicle speed V at the time when the driving force = 0, that is, when the vehicle is traveling on flat ground,
The target throttle valve opening TH is set to 2 and the engine braking force is once adjusted to the control initial value. 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
An appropriate engine braking force without excess and deficiency is obtained, and the engine braking force does not become excessive even when the road surface gradient is relatively gentle. Also, when a downshift is performed to increase the engine braking force, step SS
25 and SS20, the throttle valve opening θ is opened up to the throttle valve openings TH4 and TH2 at which the driving force becomes 0, and the throttle control is performed by steps R3 and R5 after the shift is completed. The shock does not occur due to a sudden increase.

In this embodiment, of the series of signal processing by the transmission control computer 34, step SS5 in FIG. 7, step SS17 in FIG.
Step SS20 executed when the judgment of No. 17 is NO
Corresponds to the first control means, and in step SS20,
FIG. 11 for calculating the throttle valve opening TH2
The part storing the data map corresponds to the storage means.
On the other hand, the part that executes steps R3 and R5 in FIG. 9 constitutes second control means together with the throttle control computer 35. The output shaft rotation speed N corresponding to the vehicle speed V
_The rotation speed sensor 82 that detects _O corresponds to a vehicle speed sensor.

On the other hand, in this embodiment, the engine braking force is controlled by controlling the throttle valve opening θ so that the vehicle speed V matches the target vehicle speed Vm in steps R3 and R5. The engine braking force is increased or decreased so that the vehicle speed V substantially matches the target vehicle speed Vm irrespective of the change of the vehicle speed. Is prevented from lowering. 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.
Is quickly brought close to the target vehicle speed Vm, and there is an advantage that an appropriate engine braking force can be quickly obtained.

In this embodiment, if the throttle valve opening TH3 obtained in step R3 is equal to or larger than the throttle valve opening THm at which the target vehicle speed Vm can be maintained if the vehicle is traveling on a flat ground, step R6 is executed. In this case, the throttle valve opening THm is set to the target throttle valve opening TH, so that if there is an uphill after a downhill, the vehicle speed V is made lower than the target vehicle speed Vm according to the gradient. The running control is performed as intended by the driver who thinks that the vehicle speed V will decrease.

If the driver depresses the brake to further decelerate during the control of the automatic engine braking, the control goes to step SS10 every time the determination in step SS9 becomes NO with the decrease in the vehicle speed V. Is executed, and the target vehicle speed Vm is sequentially changed according to the vehicle speed V at that time. Therefore, when the brake is released after the vehicle speed has decreased to the desired vehicle speed, the vehicle speed V at the time of releasing the brake is set to the target vehicle speed Vm, and thereafter, the engine speed is set based on the new target vehicle speed Vm at the time of releasing the brake. The braking force is controlled. This prevents the engine braking force from becoming insufficient after the brake is released.For example, even if the driver depresses the brake just before the end of the straight line on a downhill, decelerates, and then releases the brake and runs on the curve, the vehicle accelerates during the curve. And the driving operation is further facilitated.

In this embodiment, when the brake is depressed during the automatic engine brake control, the throttle valve 20 is fully closed in step SS22 or in step S48 regardless of the throttle control in steps R3 and R5. Since the engine brake force is increased by downshifting in S30, the engine brake control that matches the driver's desire to perform deceleration is performed, and the driver or the foot can reduce the brake pedaling force. The load on the brake is reduced.

In the above embodiment, even if the next shift speed is changed to 3rd in step S27 in FIG. 6, if the accelerator pedal is operated before the shift timing time T1 is reached, the next shift speed is changed in step S28. After returning to O / D, for example, as shown in FIG. 14, when the next shift speed is changed to 3rd in step S27, step S30 may be immediately executed to output the shift.

Further, in the above-described embodiment, every time the determination in step SS9 becomes NO with the decrease in vehicle speed V, step SS
10 is executed, the target vehicle speed Vm is sequentially changed according to the vehicle speed V at that time. For example, as shown in FIGS. 15 and 16, the step SS9 is omitted and the step SS11 is performed between the steps SS11 and SS12. May be provided with steps SS27 and SS28 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 danger of sudden acceleration due to insufficient engine braking force after the brake is released, and the same effect as in the above-described embodiment can be obtained in that the driving operation is further facilitated.

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

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

In the above embodiment, the throttle valve opening θ
Has been described with respect to a vehicle controlled by the throttle control computer 35, but the present invention is also applicable to a vehicle in which the throttle valve 20 is mechanically connected to an accelerator pedal to be opened and closed. Ac
Alternatively, the throttle valve opening θ can be used.

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

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

In the above-described embodiment, the vehicle speed V when the accelerator is turned off or the brake is released is set to the target vehicle speed Vm as it is. However, the target vehicle speed Vm does not need to completely match the vehicle speed V. The target vehicle speed Vm may be set by adding or subtracting a predetermined value to or from the vehicle speed V in consideration of an error or the like.

In the above embodiment, the vehicle speed V is set to the target vehicle speed V.
m, the throttle valve opening θ is feedback controlled so as to be equal to m. However, the throttle valve opening θ may be increased or decreased by a predetermined constant amount ΔTH, or the vehicle speed V
It is also possible to use other control methods such as reducing the throttle valve opening θ by a fixed amount ΔTH so that the vehicle speed does not exceed the target vehicle speed Vm. Step S
The constant value Vf in S9 is determined in consideration of the fluctuation of the vehicle speed V accompanying the control of the throttle valve opening θ. It is also possible to use other intake air amount control means for increasing the engine braking force with an increase in the vehicle speed V, such as controlling the throttle valve opening θ so that the vehicle acceleration becomes negative.

Further, in the above-described embodiment, at the time of downshifting to increase the engine braking force, step SS
At 20 or SS25, the throttle valve opening θ is opened so that the driving force becomes 0 at the speed after the shift, and after the shift is completed, the throttle valve is gradually closed by step R3 or the like.
After the shift is completed, the throttle valve opening θ can be controlled so that a braking torque substantially equal to or slightly larger than the braking torque before the shift is obtained. A data map for obtaining the throttle valve opening in this case can be created in advance using the data of FIG. 12 and the like with the gear position and the vehicle speed V as parameters, similarly to the data map of FIG.

In the above-described embodiment, only the upshift to the O / D shift stage is prohibited in step S27. However, if the engine brake is applied even at the first shift stage or the second shift stage, " A 2 → 3 shift or a 1 → 2 shift can also be prohibited. The number of gear positions of the automatic transmission 78 is also changed as appropriate.

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

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

[Brief description of the drawings]

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

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

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

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

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

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

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

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

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

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

FIG. 11 is an example of a data map used for obtaining a throttle valve opening at which a driving force in consideration of a shift speed and a vehicle speed and a running resistance becomes substantially zero in the throttle control of FIG. 8;

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

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

FIG. 14 is a flowchart corresponding to FIG. 6, illustrating another mode of the shift control for switching the shift speed of the automatic transmission.

FIG. 15 is a flowchart illustrating another embodiment related to the control of the throttle valve opening degree together with FIG.

FIG. 16 is a flowchart illustrating another embodiment related to the control of the throttle valve opening degree together 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 Step R3, R5: Second control means

Continuation of the front page (56) References JP-A-1-208236 (JP, A) JP-A-61-24626 (JP, A) JP-A-58-126446 (JP, A) JP-A-63-96257 (JP, A) , U) Actually open 63-179240 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 29/00-29/06 F02D 41/00-41/40

Claims (1)

(57) [Claims] 1. An engine brake force control device for controlling an engine brake force when an accelerator is in an off state in a vehicle provided with an automatic transmission for changing a gear ratio in accordance with a predetermined shift condition. Accelerator operation amount sensor for detecting the amount, a vehicle speed sensor for detecting the vehicle speed, intake air amount adjusting means for adjusting the amount of intake air to the engine, and the vehicle speed so as to be able to maintain a constant vehicle speed when traveling on flat ground.
And a predetermined basis using the gear ratio as a parameter.
Storage means for storing the quasi intake air amount, as well as determined that the accelerator operation amount based on an output signal of the accelerator operation amount sensor is changed to the following from the above a predetermined value of approximately zero, flat ground Running state
Reference suction that can maintain the vehicle speed when the accelerator changes
The air amount is determined based on the vehicle speed and the gear ratio when the accelerator changes.
Is obtained from the storage means and becomes the reference intake air amount.
By controlling the urchin the intake air amount adjusting means, a first control means for setting the control initial value of the engine braking force when the accelerator changes, the vehicle speed in a state in which the accelerator operation amount is equal to or less than the predetermined value As the actual vehicle speed detected by the sensor increases, the engine braking force is reduced by controlling the intake air amount adjusting means so that the intake air amount decreases below the reference intake air amount. An engine braking force control device, comprising: a second control means for increasing the control value from a control initial value.