JPH05162570A - Engine brake force control device - Google Patents

Abstract

PURPOSE:To quickly attain the engine brake force as intended by a driver when an accelerator is set to off on a downward slope. CONSTITUTION:The vehicle speed V when an accelerator is set to off is stored in EBKSPD (S9), the actual vehicle speed V is compared with the judgment vehicle speed (EBKSPD+alpha) with the preset value added to EBKSPD (S11), when the vehicle speed V is the judgment vehicle speed (EBKSPD+alpha) or above, the opening theta of a throttle valve is closed by a fixed value DELTATH1 (S14), or the speed change gear is shifted down in the step not shown in the figure to increase the engine brake force, and the engine brake force is controlled so that the vehicle speed V does not exceed the judgment vehicle speed (EBKSPD +alpha).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a downhill accelerator
The present invention relates to an improvement in an engine braking force control device that increases engine braking force when speeding up despite FF.

[0002]

2. Description of the Related Art Generally, an automatic transmission of a vehicle is designed to change a gear ratio steplessly or continuously based on an accelerator operation amount or a throttle valve opening and a vehicle speed.
FIG. 7 is an example of a shift map of an automatic transmission having four shift stages, in which the shift stages are switched based on the accelerator operation amount and the vehicle speed. Such a shift map is usually designed to upshift depending on the vehicle speed even when the accelerator operation amount is zero, that is, in the OFF state. Therefore, even when the accelerator pedal is released on a downhill, sufficient engine braking force is obtained. If the vehicle speed increases without being obtained, there is a problem that the engine braking force further decreases due to an upshift. As a countermeasure against this, if the acceleration of the vehicle is non-negative or the vehicle speed continues to increase for a certain period of time with the accelerator off, the engine braking force is increased by downshifting to increase the gear ratio of the automatic transmission. This is disclosed, for example, in JP-A-62-246650 and JP-A-61-103044.

[0003]

However, in the engine brake control in which the engine braking force that makes the acceleration of the vehicle negative is applied as described above, the acceleration actually becomes negative due to the increase of the engine braking force. While the vehicle speed increases further, it does not actively reduce the vehicle speed. Therefore, the vehicle speed may be maintained at a higher speed for a long time than the vehicle speed at the time when the driver dislikes further acceleration and turns off the accelerator. , I was not always completely satisfied. That is, when the acceleration becomes negative near 0 due to the increase of the engine braking force, the engine braking force is not increased any more, and therefore the vehicle speed does not increase but the deceleration is small and the vehicle speed is reduced to the vehicle speed when the accelerator is off. It takes a long time to operate, and during that time it is necessary to operate the brakes and operate the shift lever to a shift range with a large engine braking force, which is not always satisfactory as an automatic transmission aiming at ease of driving.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to promptly obtain the engine braking force as intended by the driver when the accelerator is turned off on a downhill or the like. Is to

[0005]

In order to achieve such an object, the engine braking force may be controlled based on the vehicle speed when the accelerator is turned off. As shown in FIG. 1, a device for controlling engine braking force of a vehicle equipped with an automatic transmission, comprising: (a) an accelerator operation amount sensor for detecting an accelerator operation amount; and (b) a vehicle speed for detecting a vehicle speed. A sensor,
(C) accelerator operation amount determination means for determining whether or not the accelerator operation amount is equal to or less than a predetermined value of substantially zero,
(D) a vehicle speed storage means for storing a vehicle speed when the accelerator operation amount determination means determines that the accelerator operation amount has changed from a predetermined value or more to a predetermined value or less; and (e) a vehicle speed storage means for storing the vehicle speed. Based on the determined vehicle speed determined based on the determined vehicle speed, a vehicle speed determination means for determining whether the actual vehicle speed exceeds the determined vehicle speed, and (f) the actual vehicle speed is determined by the vehicle speed determination means. And an engine braking force increasing means for increasing the engine braking force when it is determined that the vehicle speed is exceeded.

[0006]

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 the accelerator operation amount is determined from a predetermined value equal to or greater than approximately zero. When it is determined by the accelerator operation amount determination means that the change to the following, the vehicle speed at that time is stored in the vehicle speed storage means. Then, the determination vehicle speed is determined based on the vehicle speed, and when the vehicle speed determination means determines that the actual vehicle speed detected by the vehicle speed sensor exceeds the determination vehicle speed, the engine braking force increasing means causes the engine braking force to increase. Is increased. In other words, if the driver releases the accelerator when he / she does not want to accelerate any more on a downhill road, the judgment vehicle speed is determined based on the vehicle speed when the accelerator is released, and the actual vehicle speed does not exceed the judgment vehicle speed. The engine braking force is controlled like this.

Here, the above-mentioned judgment vehicle speed is basically the following when the accelerator operation amount changes from a predetermined value or more to a predetermined value or less,
In other words, the vehicle speed when the accelerator is released may be set, but in order to obtain the engine braking force as intended by the driver, it is not necessary to completely match the vehicle speed when the accelerator is off. It may be set in consideration of vehicle speed detection accuracy and the like. Further, as the engine braking force increasing means, in a vehicle in which a throttle valve is electronically controlled, the opening of the throttle valve may be decreased, or a vehicle provided with a stepped automatic transmission having a plurality of shift stages. May shift down to a gear position having a large gear ratio,
In a vehicle equipped with a belt type continuously variable transmission, the groove width of the variable pulley may be controlled so as to increase the gear ratio, or the electric load of an engine auxiliary device such as an alternator may be controlled. Various means such as good can be adopted. The engine braking force can be increased by using the throttle valve control and the downshift together.

[0008]

As described above, according to the engine braking force control device of the present invention, the engine braking force is controlled so that the actual vehicle speed does not exceed the judgment vehicle speed determined based on the vehicle speed when the accelerator is off. The engine speed allows the vehicle speed to be promptly controlled as intended by the driver without the need for complicated operations such as operation and shift change.

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

The engine 10 includes an intake valve 28 and an exhaust valve 4
2, a piston 44, and an ignition plug 46. The ignition plug 46 generates an ignition spark by a high voltage supplied from an igniter 48 controlled by the engine control computer 32 through a distributor 50. , The crankshaft is rotated by exploding the mixed gas in the combustion chamber 12 and moving the piston 44 up and down. The intake valve 28 and the exhaust valve 42 are adapted to be opened and closed by a cam shaft which is rotationally driven in synchronization with the rotation of the crankshaft, and by a variable valve timing mechanism (not shown) controlled by the engine control computer 32. The opening / closing timing is adjusted by changing the 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.

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. Since the one-way clutch F ₀ is provided between the sun gear 124 and the carrier 122, even if the clutch C ₀ is released in the state where power is transmitted from the engine 10, the one-way clutch F ₀ causes the clutch to move. The same effect as when the engagement control of C ₀ is performed can be obtained.

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. This transmission control computer 34
With respect to the lockup clutch of the torque converter 110 as well, the solenoid (not shown) provided in the hydraulic control circuit 150 is duty-controlled to switch between full engagement, a slip state, and an open state. Further, the throttle control computer 35 basically outputs a throttle control signal DTH based on the accelerator operation amount Ac, and controls the throttle valve opening θ of the throttle valve 20 according to the accelerator operation amount Ac. There is.

The transmission control computer 34 also operates when the automatic engine braking pattern is selected by the pattern select switch 70.
The engine braking force is automatically increased when going downhill. Hereinafter, this engine brake control will be described with reference to the flowcharts of FIGS. 5 and 6.

In FIG. 5, it is determined in step S1 whether or not the shift range represented by the shift range signal SR is "D (drive)", and in step S2 the traveling pattern represented by the pattern signal SP is "automatic engine". It is determined whether or not it is a "brake pattern", and step S3
In determining whether the reference vehicle speed Va is greater than or not the vehicle speed V is preset to correspond to the output shaft rotation speed N _O rotational speed signal SN _O represents, at step S4 accelerator represented OFF ie accelerator operation amount signal SAc It is determined whether or not the accelerator operation amount Ac is substantially zero, specifically, it is about 5% or less in consideration of a detection error and the like. The above D range is shown in FIG.
Engine braking does not work as shown in 1s
This is a case where the shift control is performed at a total of four shift speeds of t and 2nd and 3rd and O / D. Further, the reference vehicle speed Va is a speed at which the engine brake acts in the D range when the accelerator is OFF and is 3rd or more, and is a low vehicle speed that does not normally require the engine brake. 20km / as shown
The vehicle speed is set to be slightly lower than h. If even one of the steps S1 to S4 is NO, the flag F1 is set to "0" in step S5, and
In step S6, normal shift control is executed, and if the determinations in steps S1 to S4 are all YES, step S7 and subsequent steps for controlling the engine braking force are executed. It should be noted that step S3 can be omitted when the engine brake is applied at all gears, and steps S1 and S2 can be omitted when the engine braking force is controlled by all shift ranges and travel patterns. It is possible to Also, instead of step S3,
It does not matter if it is determined whether or not the gear position of the automatic transmission 78 is 3rd or more at which the engine brake acts.

The normal shift control of the step S6, the accelerator operation amount Ac (%) represented by the accelerator operation amount signal SAc Basically, and rotation speed signal SN _O represents the vehicle speed V
Based on (km / h), the shift speed of the automatic transmission 78 is switched according to the shift map of FIG. 7. For example, when the current shift speed is 3rd and the accelerator operation amount Ac is about 40%, As indicated by the alternate long and short dash line in “3 → O
The shift up vehicle speed Vu is obtained from the "/ D" shift line, and the shift down vehicle speed Vd is obtained from the "2 ← 3" shift line.
The actual vehicle speed V is compared with the shift-up vehicle speed Vu and the shift-down vehicle speed Vd to determine whether or not to shift.
Solenoids S1, S2, and S depending on the determination result
By switching between excitation and non-excitation of No. 3, the shift stage of the automatic transmission 78 is switched and controlled. The shift map is based on the pattern select switch 70.
A plurality of types are stored in advance according to a plurality of traveling patterns that can be selected by.

On the other hand, in step S7, it is determined whether or not the flag F1 is "1". Since this flag F1 is set to "0" in step S5, "1" is given when step S7 is first executed. 0 ”, and then step S8 is executed. In step S8, based on the current gear and the vehicle speed V, if the vehicle is traveling on a flat ground, the throttle valve opening for maintaining the vehicle speed V at this time, that is, the throttle valve opening in which the driving force in consideration of traveling resistance is substantially zero is opened. Degree TH
₁ (%) is calculated by map interpolation from a pre-stored data map as shown in FIG. 8, and the throttle valve opening TH ₁ is set to the target throttle valve opening TH, and the target A throttle command signal SQ indicating the throttle valve opening TH is output to the throttle control computer 35. Throttle control computer 3
When the throttle command signal SQ is supplied, the reference numeral 5 indicates a target throttle valve opening TH that represents the actual throttle valve opening θ of the throttle valve 20 by the throttle command signal SQ.
The throttle control signal DTH for matching

In the data map of FIG. 8, the throttle valve opening at which the driving force matches the running resistance is determined for each shift speed and vehicle speed on the basis of the experimentally obtained data as shown in FIG. It is a thing. The data shown in FIG. 9 is obtained in the vehicle equipped with the engine having the output characteristic shown in FIG.
The gear ratio of the automatic transmission 78 is O / D (total gear ratio = 2.8905), gear transmission efficiency is 0.855, and tire effective radius is 0.306 m. For example, when the vehicle speed is 80 km / h. Throttle valve opening TH ₁ (%)
Indicates that the throttle valve opening (angle) at point A, which matches the running resistance on a flat ground, is about 7.4 °, so when converted to%, it is (7.4 / 80) × 100 = 9.3. Becomes That is, in the data map of FIG. 8, the throttle valve opening TH when the vehicle speed is 80 km / h at the O / D gear position
₄₅ is specifically 9.3%, and in this way O /
Throttle valve opening TH _{41 to} T for each vehicle speed in the D shift stage
H ₄₇ is required. As for the 3rd gear shift stage and the 2nd gear shift stage and the 1st gear shift stage where the engine brake acts, the throttle valve openings TH _{31 to} TH ₃₇ , TH ₂₁ to TH ₂₇ , and TH ₁₁ to are the same as in the case of the O / D gear shift stage. TH ₁₇
Is required. As is clear from FIG. 9, the throttle valve opening TH ₁ increases as the vehicle speed increases, and at the same vehicle speed, the lower shift speed with a large gear ratio increases. In addition, in FIG.
Although the data regarding the shift speed and the 1st shift speed are also included, since the shift speed of the automatic transmission 78 is 3rd or O / D at the time of execution of step S8, 2n is set in this step.
The data of the d gear and the 1st gear are not used.

In the following step S9, the vehicle speed V at this time is set to the engine brake control vehicle speed EBKSPD. The vehicle speed V at this time point is a vehicle speed when the accelerator is turned from the ON state to the OFF state and the determination in step S4 is YES when the vehicle is traveling at the 3rd or O / D gear, and the driver is driving downhill. If the vehicle speed increases contrary to the above, it means the vehicle speed at which the driver dislikes further speed increase.
In the present embodiment, a portion of the series of signal processing by the transmission control computer 34 that executes the above step S9 corresponds to the vehicle speed storage means, and the step S4 described above.
The portion for executing the step corresponds to accelerator operation amount determining means.
The rotation speed sensor 82 that detects the output shaft rotation speed N _O corresponding to the vehicle speed V corresponds to a vehicle speed sensor. If the accelerator is turned off while the vehicle is running at the 1st or 2nd speed, where the engine brake does not work, and then the vehicle speed V increases on a downhill to reach the 3rd speed and exceeds the reference vehicle speed Va, The vehicle speed V when it exceeds the vehicle speed Va is set to the engine brake control vehicle speed EBKSPD.

In the next step S10, the flag F1 is set to "1", and in the subsequent cycles, the steps S8 and S9 are not executed, and immediately after step S7, steps S11 and thereafter are executed. In step S11, the current vehicle speed V is the engine brake control vehicle speed EB.
Judgment vehicle speed (EBKSPD
+ Α) or more is determined. Although the predetermined value α may be zero or negative, a very small positive value is set in this embodiment, and at the time of the first cycle, the engine brake control vehicle speed EBKSPD is set to the current vehicle speed V in step S9.
Is set, the determination in step S11 is NO. Even in the second and subsequent cycles, the determination in step S11 is NO because the vehicle speed is maintained at a substantially constant speed on the flat ground by the throttle control in step S8, but the vehicle speed V increases on a downhill road, and therefore step S11 is performed.
Is YES, and steps S12 and thereafter are executed. In the present embodiment, the step S1 in the series of signal processing by the transmission control computer 34 is performed.
The portion that executes 1 corresponds to vehicle speed determination means.

In step S12, it is determined whether or not the flag F2 is "1". If the flag F2 is "1", the steps from step S17 onward in FIG. 6 are immediately executed, but if the flag F2 is not "1". Executes step S13. In step S13, it is determined whether the actual throttle valve opening θ represented by the throttle valve opening signal Sθ is less than or equal to a predetermined determination value β, and if it is less than β, step S15 in FIG.
The following is executed, but if β is larger, step S1
4 is executed, and the target throttle valve opening TH is reduced by a predetermined constant value ΔTH ₁ . Then, the throttle command signal SQ representing the new target throttle valve opening TH is output to the throttle control computer 35 so that the throttle valve opening θ coincides with the target throttle valve opening TH, in other words, in other words. Constant value ΔTH
_It is controlled to close by ₁ , and the engine braking force is increased accordingly. The determination value β is a small value of about 5% or less, and step S14 is executed while the engine braking force can be increased by the throttle control, but the throttle valve 20 is substantially fully closed and the engine braking is performed by the throttle control. If the force cannot be increased, steps S15 and thereafter are executed. That is, in step S13, it is determined whether or not the throttle valve 20 is substantially fully closed, and it can be determined using an idle signal or the like indicating that the throttle valve opening θ is substantially fully closed.

In step S15 of FIG. 6, in order to downshift to the next low speed stage where the engine brake acts,
Excitation and non-excitation of the solenoids S1, S2 and S3 are switched. That is, when the current gear is downshifted to 3rd by O / D, the solenoid S2 is energized and the solenoids S1 and S3 are de-energized as shown in FIG. 4, and the current gear is 3rd. When downshifting to 2nd where engine braking is applied, all solenoids S1, S2, and S3 are excited, and when downshifting to 1st where engine braking is applied when the current gear is 2nd and solenoid S1 is downshifted. And S3 are energized and solenoid S2 is de-energized. By changing the gear stage of the automatic transmission 78 in this way, the gear ratio is increased and the engine braking force is increased. In the present embodiment, among the series of signal processing by the transmission control computer 34, An engine braking force increasing means is configured to include a portion that executes step S15 together with step S14, the throttle control computer 35 that is controlled according to step S14, and the throttle valve 20.

Then, the flag F2 is set to "1" in the next step S16, and the flag F2 is set in step S26.
2 is set to “0”, in other words, the above step S
Until the gear stage of the automatic transmission 78 is actually switched in accordance with the execution of step S15, the steps S13 to S16 are not executed and the step S1 is followed by the step S1.
Execute steps 7 and below immediately. In step S17, it is determined whether or not the clutch C and the brake B are in the slip state and the shift of the shift stage of the automatic transmission 78 is actually started.
The determination is made according to the following equation (1) based on the turbine rotation speed N _T , the output shaft rotation speed N _O , and the gear ratio i _H at the gear before switching. N _{1 in the} equation (1) is a positive constant value which is predetermined in consideration of the measurement error and the like, and N _T = N _O × i _H before the shift is started, so the determination in step S17 is N.
O is set, and the flag F3 is set to "0" in step S18.
And The gear ratio i of each gear of the automatic transmission 78 is stored in advance.

[0029]

## EQU1 ## N _T ≧ N _O × i _H + N ₁ (1)

Solenoids S1 and S in step S15
When the clutch C and the brake B start to slip due to the switching of excitation and non-excitation of S2 and S3, and the determination in step S17 is YES, then step S19 is executed to switch the shift stage of the automatic transmission 78. Is completed,
The determination is made according to the following equation (2) based on the turbine rotation speed N _T , the output shaft rotation speed N _O , and the gear ratio i _L at the gear after the switching. N _{2 in the} equation (2) is a positive constant value which is predetermined in consideration of measurement error and the like, and when the shift stage is completely completed, N _T = N _O × i _L and the determination in step S19 is made. Although the result is YES, the determination in step S19 is NO during the shifting of the shift stage, that is, during the shift in which the clutch C and the brake B are in the slipping state, and steps S20 and thereafter are executed.

[0031]

(2) N _T ≧ N _O × i _L −N ₂ (2)

In step S20, it is determined whether the flag F3 is "1". In step S18, the flag F3 is determined.
Is "0", the determination in step S20 is initially NO, and step S21 is executed. In step S21, based on the gear position after switching and the current vehicle speed V, if the vehicle is traveling on a flat surface, the throttle valve opening, that is, the driving resistance that allows the current vehicle speed V to be maintained even after the gear position is switched, that is, driving resistance. Throttle valve opening TH ₂ where the force becomes zero
(%) Is calculated by map interpolation from the data map of FIG. 8 similarly to the throttle valve opening TH _1, and
The value (TH ₂ + ΔTH ₂ ) obtained by adding a constant value ΔTH ₂ to the throttle valve opening TH ₂ is the target throttle valve opening TH.
And the throttle command signal SQ representing the target throttle valve opening TH is set to the throttle control computer 35.
The throttle valve opening θ is controlled so that it becomes equal to the throttle valve opening (TH ₂ + ΔTH ₂ ). Since the constant value ΔTH ₂ needs to increase the engine rotation speed NE when downshifting, the crankshaft 1
Although the value is preset in consideration of the inertia of 18 and the torque converter 110, it may be set according to the vehicle speed V or the like by an arithmetic expression or a map.
When the throttle valve opening θ is controlled in this way, the engine rotational speed NE is rapidly increased to a rotational speed according to the gear ratio i _L of the gear after switching and the current vehicle speed V, so that the clutch C and the brake are The rotational speeds of the friction engagement elements B are quickly matched, and the time (shift time) required to switch the shift stage of the automatic transmission 78 that does not provide sufficient engine braking force is shortened.

In the next step S24, the flag F3 is set to "1", and in the subsequent cycles, step S22 is executed after step S20. In step S22, it is determined whether or not the turbine rotation speed N _T is equal to or higher than the engine rotation speed NE, in other words, whether or not the engine is in a braking state, and if NO, that is, if the engine driving state is N _T <NE, then in step S23. Then, the target throttle valve opening TH is reduced by a predetermined constant value ΔTH ₃ . Then, by outputting the throttle command signal SQ representing the new target throttle valve opening TH to the throttle control computer 35, the throttle valve opening θ
Is controlled to coincide with the target throttle valve opening TH, in other words, to be closed by a constant value ΔTH ₃ . This is because the throttle valve opening θ
This is because the engine is driven by the predetermined amount depending on the gear ratio i _L of the gear position after switching, but it is not preferable.

When the shift stage of the automatic transmission 78 is completed and the determination in step S19 becomes YES, step S25 is subsequently executed, and the throttle valve opening θ at the shift stage before the shift is equal to the determination value β. The throttle valve opening TH ₃ that provides a braking torque substantially the same as or slightly larger than the braking torque in this case even after the shift is calculated by map interpolation from a predetermined data map based on the shift speed and the vehicle speed. Then, the throttle valve opening TH ₃ is set to the target throttle valve opening TH, and the throttle command signal SQ representing the target throttle valve opening TH is output to the throttle control computer 35, whereby the throttle valve opening θ Is controlled to the throttle valve opening TH ₃ . The data map is created in advance on the basis of the data shown in FIG. 9 and the judgment value β obtained for each shift speed. Then, step S26 is executed and the flag F is set.
2 is set to "0".

By repeating the above steps, the engine braking force is controlled so that the actual vehicle speed V does not exceed the determination vehicle speed (EBKSPD + α) while YES in steps S1 to S4 continues. It As is clear from the above description, the normal speed change determination is not performed in step S7 and subsequent steps for controlling the engine braking force, and therefore the vehicle speed V during 3rd running is "3 → O /" in FIG.
It does not upshift to the O / D gear even if it exceeds the "D" shift line.

As described above, in this embodiment, 3rd or O
When the accelerator changes from the ON state to the OFF state while traveling at the / D gear, the vehicle speed V at that time is set to the engine brake control vehicle speed EBKSPD in step S9, and the engine brake control vehicle speed EBKSPD is set to a predetermined value α. The determination vehicle speed (EBKSDP + α) is determined by the addition, and the vehicle speed V is determined by the determination vehicle speed (EBKSPD + α).
In the above case, the engine braking force is increased by closing the throttle valve opening θ by a constant value ΔTH ₁ in step S14 or by downshifting in step S15. That is, when the driver releases the accelerator when he / she does not want to accelerate further downhill or the like, the determination vehicle speed (EBKSPD + α) is determined based on the vehicle speed when the accelerator is released, and the actual vehicle speed V is determined by the determination. Vehicle speed (EBKSPD +
The engine braking force is controlled so that it does not exceed α), which allows the vehicle speed to be controlled quickly by the engine brake without the need for troublesome operations such as braking and shift changes. Is done.

Further, when performing a downshift to increase the engine braking force, the throttle valve opening TH _{2 at} which the current vehicle speed V is maintained even after the gear shift is calculated, and the throttle valve opening TH ₂ is calculated. Since the throttle valve opening θ of the throttle valve 20 is controlled so as to be a value (TH ₂ + ΔTH ₂ ) obtained by adding a constant value ΔTH ₂ to the degree TH ₂ , the engine speed NE is rapidly increased and the clutch C is increased. The rotation speeds of the friction engagement elements of the brake B and the brake B are quickly matched, and the shift time of the automatic transmission 78 in which a sufficient engine braking force is not obtained is shortened. As a result, the range of increase of the vehicle speed V at the time of gear shifting of the automatic transmission 78 becomes small,
The vehicle speed V is brought closer to the judgment vehicle speed (EBKSPD + α) more quickly.

Further, in this embodiment, the throttle valve opening θ is closed by a constant value ΔTH ₁ to increase the engine braking force. On the other hand, when the throttle valve opening θ is almost fully closed, the engine is downshifted. Since the throttle valve opening degree θ is controlled so as to obtain a braking torque that is substantially the same as or slightly larger than the braking torque before the downshift, the engine braking force is gradually increased, including during the downshift,
A shock due to a change in engine braking force is hardly generated.

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

For example, in the above embodiment, the vehicle in which the throttle valve opening θ is controlled by the throttle control computer 35 has been described, but the present invention is also applicable to a vehicle in which the throttle valve 20 is mechanically connected to the accelerator pedal to open and close. The invention is applicable, in which case the engine braking force can be controlled by downshifting, or the engine braking force can be controlled by controlling the electrical load of the engine auxiliary equipment such as an alternator. The throttle position sensor 36 may be used as the sensor.

Further, in the above embodiment, the engine braking force is automatically controlled when the automatic engine braking pattern is selected by the pattern select switch 70, but when another running pattern such as the power pattern is selected. Alternatively, the engine braking force may be automatically controlled, or the engine braking control may be executed regardless of the type of traveling pattern.
It is of course possible to dispose the engine brake control switch separately from the pattern select switch 70.

Further, in the above embodiment, the throttle valve opening θ is opened in step S8, but step S8 may be omitted in order to increase the engine braking force more quickly.

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.

5 is a flowchart illustrating the operation of the engine braking force control device of FIG. 2 together with FIG.

6 is a flowchart illustrating the operation of the engine braking force control device of FIG. 2 together with FIG.

FIG. 7 is an example of a shift map for switching the shift speed of the automatic transmission of FIG.

FIG. 8 is an example of a data map used in steps S8 and S21 of FIGS. 5 and 6 to obtain a throttle valve opening at which the driving force in consideration of running resistance is approximately zero from the shift speed and the vehicle speed.

FIG. 9 is basic data for creating the data map of FIG.

10 is data showing the output characteristics of the engine used to obtain the basic data of FIG. 9. FIG.

[Explanation of symbols]

 20: Throttle valve 34: Transmission control computer 35: Throttle control computer 76: Accelerator operation amount sensor 78: Automatic transmission 82: Output shaft rotation speed sensor (vehicle speed sensor) V: Vehicle speed EBKSPD + α: Judgment vehicle speed Step S4: Accelerator operation Quantity determination means Step S9: Vehicle speed storage means Step S11: Vehicle speed determination means Steps S14 and S15: Engine braking force increasing means

Claims (1)

[Claims] 1. A device for controlling engine braking force of a vehicle having an automatic transmission, wherein an accelerator operation amount sensor for detecting an accelerator operation amount, a vehicle speed sensor for detecting a vehicle speed, and the accelerator operation amount are substantially the same. An accelerator operation amount determining means for determining whether or not it is less than or equal to a predetermined value of zero, and when the accelerator operation amount determining means determines that the accelerator operation amount has changed from a predetermined value or more to below. Vehicle speed storage means for storing the vehicle speed, and vehicle speed determination means for determining whether or not the actual vehicle speed exceeds the determination vehicle speed with reference to the determination vehicle speed determined based on the vehicle speed stored in the vehicle speed storage means. And an engine braking force increasing means for increasing the engine braking force when the vehicle speed determining means determines that the actual vehicle speed exceeds the determination vehicle speed. The engine braking force control device to be used.