JPH0632155A - Engine controller - Google Patents

Abstract

PURPOSE:To relax the load of a controller and raise the responsiveness, in constant velocity running control. CONSTITUTION:This engine controller is equipped with a constant velocity running instructive switch 25 for instructing constant velocity running control, a car speed sensor 21 for detecting car speed, a constant velocity objective target torque calculator 2 for deciding the target driving torque to the car speed being detected with a car speed sensor 21, using the target driving torque property curve being set to show the relation with the target driving torque of an axle capable of maintaining the error between the car speed detected with the car speed sensor 21 and the target car speed within a specified range, and engine output operation amount calculating means 3, 4 and 5 seeking the throttle aperture capable of generating the decided target driving torque with the axle and outputting this throttle aperture to a throttle valve 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for controlling an engine by outputting a throttle opening or the like to an engine output operating means such as a throttle valve, and more particularly to a constant speed running control. The present invention relates to a controllable engine control device.

[0002]

2. Description of the Related Art As a conventional engine control device for performing constant speed traveling control, there is, for example, one disclosed in Japanese Patent Laid-Open No. 64-22637. This control device obtains the deviation between the target vehicle speed and the current vehicle speed, calculates the drive torque on the output side of the transmission necessary to obtain the target vehicle speed from this deviation, and then calculates the drive torque and the state of the transmission. The throttle valve operation amount is determined in consideration of the above factors, and the throttle valve is controlled so that this operation amount is achieved to realize constant speed traveling control.

[0003]

However, in the conventional constant-speed traveling control device, after detecting the current vehicle speed, the deviation between this vehicle speed and the target vehicle speed is obtained, and from this deviation, a multi-step calculation process is performed, For the first time, since the drive torque on the output side of the transmission that is necessary to obtain the target vehicle speed is obtained, this calculation must be executed constantly during constant-speed running control, resulting in an excessive load on the control device. There is a problem that
Furthermore, during constant-speed traveling control, for example, when the traveling resistance changes abruptly, the driving torque required to obtain the target vehicle speed cannot be immediately obtained, and the deviation between the vehicle speed and the target vehicle speed is not detected several times. There is also a problem that the response is not so good because the drive torque that is commensurate with the running resistance is obtained for the first time after obtaining the drive torque each time.

The present invention has been made in view of such conventional problems, and an object thereof is to provide an engine control device capable of reducing the calculation load of the device and enhancing the responsiveness. .

[0005]

To achieve the above object, an engine control device includes a vehicle speed detecting means for detecting a vehicle speed, and a vehicle speed detected by the vehicle speed detecting means and a target vehicle speed within a predetermined error range. A characteristic curve setting means for setting a target drive torque characteristic curve showing a relationship with a possible target drive torque of the axle, and a target for the vehicle speed detected by the vehicle speed detection means by using the set target drive torque characteristic curve. Target drive torque determining means for determining a drive torque, and an engine output operation amount for obtaining an engine output operation amount capable of generating the determined target drive torque on the axle and outputting the engine output operation amount to the engine output operation means. And a calculating means.

Another engine control device for achieving the above object is a switching signal output means for outputting a switching signal for switching between constant speed traveling control and normal traveling control, and vehicle speed detecting means for detecting the vehicle speed. An accelerator opening detection means for detecting an operation amount of the accelerator pedal, a storage means for storing a target drive torque characteristic curve of an axle during normal traveling according to an operation amount of the accelerator pedal and a vehicle speed, and the storage means. Using the stored target drive torque characteristic curve, a normal target drive torque determination means for determining a target drive torque with respect to the detected vehicle speed and the operation amount of the accelerator pedal, and constant speed running from the switching signal output means. The vehicle speed at the time when the switching signal for switching to the control is output is set as the target vehicle speed, and the target drive speed of the axle that can maintain the target vehicle speed within the predetermined error range. Characteristic curve setting means for setting a target drive torque characteristic curve indicating a relationship between the vehicle speed detected by the vehicle speed detection means and the target drive torque characteristic curve set by the characteristic curve setting means. It is determined by one of the constant speed target drive torque determining means for determining the target drive torque for the vehicle speed detected by the vehicle speed detecting means, the normal target drive torque determining means, and the constant speed target drive torque determining means. The target drive torque output switching means that outputs the target drive torque determined by the switching signal output means and outputs the target drive torque determined by the switching signal output means. The obtained target drive torque is obtained as an engine output operation amount that can be generated on the axle, and the engine output operation amount is output to the engine output operation means. And it is characterized in that it comprises an engine output control input calculation means.

Here, as the engine output manipulated variable, specifically, the opening degree of the throttle valve (= intake air flow rate) and the opening degree of the fuel injection valve (= fuel injection amount) capable of changing the engine output. ) And ignition timing.

[0008]

The characteristic curve setting means sets the target drive torque characteristic curve corresponding to the target vehicle speed. The target drive torque determination means determines the target drive torque for the vehicle speed detected by the vehicle speed detection means, using the set target drive torque characteristic curve. In this way, since the target drive torque curve is used, the target drive torque for the current vehicle speed can be immediately obtained without performing any number of calculations.
The load on the control device can be reduced. Further, even when the running resistance changes abruptly during the constant speed running control, the driving torque required to maintain the target vehicle speed can be immediately obtained from the target driving torque curve, and the responsiveness can be improved. .

The engine output manipulated variable calculating means obtains an engine output manipulated variable capable of generating the determined target drive torque on the axle. The engine output operation means operates the operation amount so as to obtain this engine output operation amount. The engine generates an engine torque corresponding to this manipulated variable. That is, the engine generates an engine torque such that a drive torque capable of maintaining the target speed is obtained on the axle. Therefore, the vehicle maintains the target vehicle speed within the allowable error range.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of an engine control device according to the present invention will be described below with reference to the drawings. First, a first embodiment of the engine control device will be described with reference to FIGS. As shown in FIG. 1, the engine control apparatus according to the present embodiment includes an engine control unit 10, a vehicle speed sensor 21, an accelerator opening sensor 22, and a constant speed travel instruction for a driver to instruct constant speed travel control. The switch 25 and the target drive torque output switching unit 26 are included.

In terms of software, the engine control unit 10 includes a normal target drive torque calculating section 1 for calculating a drive torque required for an axle from the accelerator opening and the vehicle speed during normal traveling, and during constant speed traveling control. A constant speed target drive torque calculation unit 2 that calculates a drive torque required for the axle only from the vehicle speed, and a transmission input shaft torque calculation unit 3 that converts the calculated target drive torque into the torque of the transmission input shaft 37.
An engine torque calculation unit 4, a throttle opening calculation unit 5, and a fuel ignition control unit 6 for controlling fuel and ignition timing.
And have.

In the normal target drive torque calculating section 1, the target drive torque characteristic curves a and b as shown in FIG. 4 are stored in a state of being developed on the map in advance. As shown in FIG. 3, the constant speed target drive torque calculation unit 2 recognizes a point represented by the vehicle speed v and the target drive torque τ as an operation point Q (v, τ), and an operation point grasping unit 2a. A target drive torque characteristic X is determined from the determined operating point Q, the target drive torque characteristic setting unit 2b that develops the target drive torque characteristic X on the map, and a target drive torque determination that determines the target drive torque with respect to the vehicle speed detected from the target drive torque characteristic X are determined. And a portion 2c. Also,
As shown in FIG. 5, the engine torque calculation unit 4 stores the characteristic curve of the torque converter 36 in advance, and the throttle opening calculation unit 5 stores the engine 33 as shown in FIG.
Is previously stored.

The engine control unit 10 is configured as described above in terms of software, but in terms of hardware, as shown in FIG. 2, an input interface circuit 11 and a CPU 12 that executes various calculations. And ROM 13 and RAM for storing various data and programs
14 and an output interface circuit 15. That is, the drive torque characteristic curve, the torque converter characteristic curve, the engine characteristic curve, etc. are stored in the RAM 14
The calculation program executed by each of the calculation units 1, 2, ... Is stored in the ROM 13,
The CPU 12 has the ROM 1 for the functions of the respective calculation units 1, 2, ...
3 and the programs stored in the ROM 14 are executed.

As shown in FIG. 3, the target drive torque output switching unit 26 outputs only one of the output from the normal target drive torque calculating unit 1 and the output from the constant speed target drive torque calculating unit 2 to the transmission. It is output to the input shaft torque calculation unit 3, and when the constant speed traveling instruction switch 25 is turned on, each contact is operated by the excitation of the coil 27, and the constant speed target drive torque calculation unit 2 outputs Only the output is output to the transmission input shaft torque calculation unit 3.

In this embodiment, the switching signal output means is composed of the constant speed traveling instruction switch 25, the storage means and the normal target drive torque determining means are composed of the normal target drive torque calculating section 1, and the characteristic curve is shown. The setting means and the constant speed target drive torque determining means are configured by the constant speed target drive torque calculating section 2. Further, the engine output operation amount calculation means is composed of the transmission input shaft calculation part 3, the engine torque calculation part 4 and the throttle opening degree calculation part 5, and the engine output operation means is composed of the throttle valve 31.

Next, the operation of the engine control system according to this embodiment will be described. First, a description will be given of the case of normal traveling, that is, the case where the constant speed traveling instruction switch 25 is off and the target drive torque output switching unit 26 is at the position a shown in FIGS. 1 and 3. As shown in FIG. 4, the target drive torque calculation unit 1 obtains the target drive torque using the target drive torque characteristic curves a and b and the outputs from the accelerator opening sensor 22 and the vehicle speed sensor 21.

The target drive torque characteristic curve will be described with reference to FIG. In the figure, the horizontal axis represents the vehicle speed (km / h) and the vertical axis represents the drive torque (kg-
m) is shown. Further, A and B are drive torque characteristics when the accelerator pedal 32 and the throttle valve are mechanically linked, A shows a drive torque characteristic when the accelerator pedal is fully depressed, and B shows a drive torque characteristic when the accelerator pedal 32 is fully depressed. The drive torque characteristics are shown. When the accelerator pedal 32 and the throttle valve are mechanically linked, as shown in FIGS. A and B, the torque suddenly decreases as the speed increases in the low speed range, so the feeling of acceleration does not continue, and in the high speed range. Since the characteristic is sleeping, even if the running resistance curve changes slightly in the vertical direction, the balance speed fluctuates and the vehicle speed stability is poor.

Therefore, if the electronically controlled throttle valve 31 is used, an arbitrary torque can be produced as long as it is equal to or less than the maximum torque curve A. The vehicle speed stability is improved by making the angle constant with the running resistance curve at a right angle by making it substantially constant so that a constant acceleration can be obtained, and by making it droop in the high speed range. It should be noted that, for example, if a characteristic curve in which the torque increases as the speed increases, such as the target drive torque characteristic curve c, is stored in advance, a characteristic suitable for sports cars in which the feeling of acceleration is emphasized can be obtained. it can. Further, if a characteristic curve giving a torque limit value at the time of starting is stored in advance like the target drive torque characteristic curve d, the torque above this torque will not be applied to the axle at the time of starting. The parts can be downsized to reduce the weight of the vehicle body. Transmission input shaft torque calculation unit 3
Converts the target drive torque and the rotational speed of the axle into the target torque and the rotational speed of the transmission input shaft 37, respectively, based on the gear ratio information provided by the transmission control device 20. This conversion is performed by a simple proportional calculation for both torque and rotation speed. The rotation speed of the axle (= transmission input shaft) is obtained as an output from the vehicle speed sensor 21.

As is well known, the torque converter 36 has a function of amplifying torque due to slippage between the pump and the turbine. Therefore, from the torque amplification factor, the target engine torque (= target at the input shaft of the torque converter 36). At the same time that the torque is calculated, the slip must be corrected and the target engine speed must be calculated. Generally, as shown in FIG. 5, the characteristics of a torque converter are as follows: the horizontal axis is the rotational speed ratio e = n ₂ / n ₁ between input and output, the torque ratio between input and output t = T ₂ / T ₁ , and the capacity coefficient. It is represented by Cp = T ₁ / n ₁ ² . Here, n ₁ : input rotation speed (engine rotation speed), n ₂ : output rotation speed (transmission input shaft rotation speed), T ₁ :
Input torque (engine torque), T ₂ : output torque (transmission input shaft torque). The capacity coefficient Cp represents the individuality of the torque converter, and is a characteristic determined by its size and structure. Here, the capacity coefficient Cp is expressed by the torque T ₁ on the input side and the rotation speed n ₁ , but when this Cp ′ is expressed by the torque T ₂ on the output side and the rotation speed n ₂ , Can be expressed as

Cp ′ = T ₂ / n ₂ ² = tCp / e ² (Equation 1) Therefore, in the engine torque calculation unit 4, The transmission input target torque obtained in step 1 is set to T ₂ , the transmission input shaft rotation speed at that time is set to n ₂ , and Cp ′ is obtained using (Equation 1).
The transmission input shaft rotational speed n ₂ is obtained from the axle rotational speed obtained from the vehicle speed sensor 21 and the gear ratio. When the capacity coefficient Cp ′ is determined, the rotational speed ratio e and the torque ratio t are determined from the torque converter characteristics shown in FIG. 5, so the target engine torque and the target engine rotational speed are obtained.

As shown in FIG. 6, the throttle opening calculation unit 4 calculates the throttle opening from the engine torque characteristic and the target engine torque and the target rotation speed obtained by the engine torque calculation unit 4. The throttle opening thus obtained is used as a signal for the electronically controlled throttle valve 3
1 and set to the calculated throttle opening. Further, the fuel injection / ignition control unit 6 obtains an optimum fuel injection amount and ignition timing according to the set throttle opening degree, and executes control so as to reach the fuel injection amount and ignition timing. Axial torque is obtained.

Next, in the constant speed traveling control, that is, in the case where the constant speed traveling instruction switch 25 is turned on and the target drive torque output switching section 26 is at the position b shown in FIGS. 1 and 3, FIG.
It will be described according to the flowchart shown in. In the constant speed target drive torque calculation unit 2, as shown in FIG. 7, the operating point grasping unit 2a operates at the operating point Q (v, τ) corresponding to the current vehicle speed v on the target drive torque characteristic curve b during normal traveling. ) Is always grasped (step 1). Constant speed running instruction switch 25
Is turned on, the constant speed control flag is checked, and if the flag is 0 (step 3), the operating point Q ₁ (v ₁ ,
The target driving torque characteristic setting unit 2b acquires the data of (τ ₁ ) (step 4), sets the constant speed control flag to 1 (step 5), and then the target passing through this operating point Q ₁ (v ₁ , τ ₁ ). The drive torque characteristic curve X ₁ is set (step 6).

As the target drive torque characteristic curve X _1, as described above, a straight line which intersects the running resistance at a substantially right angle and which sharply changes with respect to the change of the vehicle speed so that the vehicle speed stability is improved is used. When obtaining the target drive torque characteristic curve X ₁ , first, the operating point Q ₀ (v ₀ , 0) at which the target drive torque is 0 is larger than v _{1 at} the operating point Q ₁ by the allowable speed error Δv%. (V ₀ = v ₁ (1 + Δv)) is calculated. Then, a straight line (shown in (Equation 2)) passing through the operating point Q ₀ and the operating point Q ₁ is set as the target drive torque characteristic curve X ₁ , and this is developed on the map. τ _S = τ ₁ / (v ₁ −v ₀ ) + τ _S (v = 0) ... (Equation 2) The target drive torque determination unit 2c is If the constant speed control flag is checked and the flag is 1, the target drive torque characteristic curve X ₁ has already been set. Therefore, the target drive torque characteristic curve X ₁ is used to correspond to the current speed v that is sequentially input. The target drive torque τ _S is determined and is output to the transmission input shaft torque calculation unit 3 via the target drive torque output switching unit 26 (step 7), and the processing in the target drive torque calculation unit 2 ends. .

Thus, once the target drive torque characteristic curve X ₁ is set, the current vehicle speed v is set on the characteristic curve X _1.
Since the target drive torque τ _S can be calculated only by satisfying the above, the load on the control device can be reduced.

The target drive torque τ _S calculated by the target drive torque calculation unit 2 is then processed in the same manner as during the normal running described above. Further, during normal traveling, the vehicle speed and the accelerator opening are read (step 1), and when the constant speed traveling instruction switch 25 is off (step 2), the constant speed control flag is set to 0 (step 8) and the map is set. The target drive torque characteristic curve developed above is used to calculate the target drive torque corresponding to the vehicle speed and the accelerator opening degree, and the processing in the target drive torque calculation unit 1 ends.

As described above, regarding the operation of the vehicle when the drive torque is controlled during the constant speed traveling control,
This will be described with reference to FIG. When the torque τ _{1 at} the operating point Q ₁ when the constant speed traveling instruction switch 25 is turned on is larger than the traveling resistance characteristic curve L ₁ , the operating point Q ₁ is not stable, and the characteristic curve X ₁ and the traveling resistance characteristic curve are not stable. It stabilizes at the intersection Q ₂ with L _1, and runs at a constant speed at the vehicle speed v ₂ . When the running resistance characteristic curve changes from this state to L ₂ , the operating point passes over the target drive torque characteristic curve X ₁ and the torque increases, and the intersection Q ₃ with the running resistance characteristic curve L ₂ becomes a stable point, and the vehicle speed is increased. It will run at a constant speed at v ₃ . As described above, even if the running resistance changes rapidly, the target driving torque characteristic curve X ₁ is mapped, so that the target driving torque that matches the running resistance can be immediately obtained, and the responsiveness can be improved. it can.

In the above embodiment, the target drive torque characteristic curve is set each time constant speed running is instructed. However, as shown in FIGS. 9 and 10, a plurality of target drive torques are set in advance. A characteristic curve is stored in a map, one characteristic curve is selected from a plurality of characteristic curves from the operating point when the constant speed running instruction switch 25 is turned on, and this characteristic curve is used. Good. here,
9 shows the characteristic curve having a smaller slope and the allowable error speed becoming larger as the set speed increases, and FIG. 10 shows the characteristic curve having a constant slope. is there.

Next, a second embodiment of the engine control device according to the present invention will be described. In the present embodiment, in addition to the constant speed traveling instruction switch 25, a speed change instruction switch for giving acceleration and deceleration instructions is provided, and by operating this switch during constant speed traveling, the target drive torque characteristic curve initially set. Is set so that the set vehicle speed can be increased or decreased.

Specifically, as shown in FIGS. 11 and 12, when the speed change switch is pushed to the speed increasing side during constant speed running (step 10), the target drive torque characteristic initially set is set. The curve X ₁ is moved in parallel by + Δτ to set a new target drive torque characteristic curve X ₂ (step 1
1, 6). Due to the parallel movement of the target drive torque characteristic curve, the point Q ₄ balanced with the running resistance moves to the right side in FIG. 11, and the vehicle speed increases. When the speed change switch is pushed to the deceleration side (step 10), the target drive torque characteristic curve X ₁ initially set is moved in parallel by -Δτ to set a new target drive torque characteristic curve X ₄ ( Steps 12, 6). In this way, the target drive torque characteristic curve is moved in parallel to increase or decrease the set vehicle speed during constant speed traveling control.

Next, a third embodiment of the engine control device according to the present invention will be described with reference to FIG. In the first embodiment, the switching operation of the target drive torque output switching unit 26 is executed according to the operation of the constant speed traveling instruction switch 25. However, in the present embodiment, the accelerator opening degree is used instead of the constant speed traveling instruction switch. A switching signal output unit 39 that outputs a switching signal to the switching unit 26 is provided in conjunction with. For example,
It is assumed that the accelerator opening and the output voltage characteristic of the accelerator opening sensor 22 are as shown in FIG. The switching signal output unit 39 has a threshold value Vth set for the output voltage of the accelerator opening sensor 22, and when the output voltage of the accelerator opening sensor 22 becomes less than or equal to the threshold value Vth, the switching unit 26 outputs The contact is switched to the b side, and when the threshold value Vth is exceeded, a switching signal is output so as to switch the contact of the switching unit 26 to the a side.

Generally, in constant speed running, the accelerator pedal 32 is used.
Drive away from. Therefore, in the present embodiment, when the driver releases the accelerator pedal 32 during normal traveling and the accelerator opening becomes small, a switching signal is output from the switching signal output unit 39 so that the vehicle can shift to constant speed traveling control. There is. In addition, while the vehicle is traveling at a constant speed, the driver can
When the accelerator opening is increased by depressing, the switching signal output unit 39 outputs the switching signal again, and the normal traveling control is resumed. Although some accelerator pedals 32 are provided with a fully closed switch, a switching signal may be output in conjunction with this. Further, the constant-speed traveling can be released by depressing the brake petal or manually by providing a release switch separately.

Next, a fourth embodiment of the engine control device according to the present invention will be described with reference to FIG. In the target drive torque characteristic curve X ₁ , when the traveling resistance characteristic frequently changes between L ₃ and L ₄ at the transition between the third and fourth gear ratios during constant speed traveling, frequent gear shifting is performed. In addition, the shift shock makes the ride uncomfortable. By the way, the fuel ignition control unit 6 controls the ignition of the engine and the injection of fuel, and the torque of the engine can be adjusted by adjusting these controls. Therefore, when the running resistance characteristic changes at the change of the gear ratio and the torque change at that time is small, the transmission control device 20 is instructed not to perform the shift, and the fuel ignition control unit 6 adjusts the torque. To do. By executing such control, it is possible to prevent the ride comfort from being deteriorated due to frequent gear shifts during constant speed traveling.

Next, a fifth embodiment according to the present invention will be described with reference to FIG. In this embodiment, a control compensator 7 is added to the output of the constant speed target drive torque calculator 2. The steeper the target drive torque characteristic curve X _1, the smaller the error from the set vehicle speed, but the greater the gain of the control system, and the worse the stability of the control. Therefore, the control compensator 7 performs gain compensation and phase compensation. According to this embodiment, it is possible to stably control the constant speed running.

The various embodiments of the engine control device according to the present invention have been described above. In these embodiments, the opening of the throttle valve is used as the engine output manipulated variable. The present invention is not limited to this, and the opening degree of the fuel injection valve and the ignition timing may be used as the engine output manipulated variable. In particular, in the case of a diesel engine, it goes without saying that the fuel injection valve should be used as the engine output manipulated variable.

[0035]

According to the present invention, since the target drive torque characteristic curve is once set, the target drive torque with respect to the vehicle speed can be immediately obtained using this, and the load on the control device can be reduced. It is possible to improve the responsiveness.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an engine control device according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of an engine control unit according to a first embodiment of the present invention.

FIG. 3 is a functional block diagram of a constant speed target drive torque calculation unit of the first embodiment according to the present invention.

FIG. 4 is a graph showing a target drive torque characteristic curve during normal traveling control according to the first embodiment of the present invention.

FIG. 5 is a graph showing characteristics of a torque converter.

FIG. 6 is a graph showing torque characteristics of the engine.

FIG. 7 is an explanatory diagram for explaining setting of a constant speed target drive torque characteristic curve of the first embodiment according to the present invention. .

FIG. 8 is a flowchart showing an operation of a target drive torque calculation unit of the first embodiment according to the present invention.

FIG. 9 is a graph showing a target drive torque characteristic curve of a modification of the first embodiment according to the present invention.

FIG. 10 is a graph showing a target drive torque characteristic curve of another modification of the first embodiment according to the present invention.

FIG. 11 is a graph showing a target drive torque characteristic curve of the second embodiment according to the present invention.

FIG. 12 is a flowchart showing an operation of a target drive torque calculation section of the second example according to the present invention.

FIG. 13 is an explanatory diagram showing a configuration of a main part of an engine control device according to a third embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a relationship between a target drive torque characteristic curve and a running resistance curve for explaining a fourth embodiment according to the present invention.

FIG. 15 is an explanatory diagram showing a configuration of a main part of an engine control device according to a fifth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Normal target drive torque calculation unit, 2 ... Constant speed target drive torque calculation unit, 3 ... Transmission input shaft torque calculation unit, 4 ... Engine torque calculation unit, 5 ... Throttle opening calculation unit, 6 ... Fuel ignition control unit , 7 ... control compensator, 10 ... engine control unit, 12 ... CPU, 13 ... ROM, 14 ... RAM, 2
0 ... Transmission control device, 21 ... Vehicle speed sensor, 22 ... Accelerator pedal opening sensor, 25 ... Constant speed running instruction switch, 2
6 ... Target drive torque output switching unit, 31 ... Throttle valve, 33 ... Engine, 34 ... Axle, 35 ... Transmission, 36
… Torque converter.

Claims (7)

[Claims] Claim: What is claimed is: 1. An engine control device, which outputs an engine output operation amount capable of maintaining a target vehicle speed to an engine output operation means to control an engine to realize constant speed running, and vehicle speed detection means for detecting a vehicle speed, Characteristic curve setting means for setting a target drive torque characteristic curve showing a relationship between a vehicle speed detected by the vehicle speed detection means and a target drive torque of an axle capable of maintaining the target vehicle speed within a predetermined error range, Target drive torque determining means for determining a target drive torque with respect to the vehicle speed detected by the vehicle speed detecting means using the target drive torque characteristic curve; and engine output operation capable of generating the determined target drive torque on the axle. And an engine output operation amount calculation means for obtaining the amount and outputting the engine output operation amount to the engine output operation means. The engine control apparatus according to. 2. A switching signal output means for outputting a switching signal for switching between the constant speed traveling control and the normal traveling control, wherein the characteristic curve setting means outputs the switching signal for switching to the constant speed traveling control. 2. The engine control apparatus according to claim 1, wherein the target drive torque characteristic curve is set with the vehicle speed at the target vehicle speed as the target vehicle speed. 3. An engine control device for controlling an engine by outputting an engine output manipulated variable to an engine output operating means, and switching signal output means for outputting a switching signal for switching between constant speed traveling control and normal traveling control. A vehicle speed detecting means for detecting a vehicle speed, an accelerator opening detecting means for detecting an operation amount of an accelerator pedal, and a target drive torque characteristic curve of an axle during normal traveling according to the operation amount of the accelerator pedal and a vehicle speed are stored. And a normal target drive torque determining means for determining a target drive torque with respect to the detected vehicle speed and the operation amount of the accelerator pedal, using the storage means to be stored and the target drive torque characteristic curve stored in the storage means. The target vehicle speed is the vehicle speed at the time when the switching signal for switching to the constant speed traveling control is output from the switching signal output means, Characteristic curve setting means for setting a target drive torque characteristic curve indicating the relationship between the target drive torque of the axle capable of maintaining the target vehicle speed within a predetermined error range and the vehicle speed detected by the vehicle speed detection means, and the characteristic curve setting means. Using the target drive torque characteristic curve set by the means, a constant speed target drive torque determination means for determining a target drive torque for the vehicle speed detected by the vehicle speed detection means, the normal target drive torque determination means and the constant The target drive torque determined by one of the high speed target drive torque determining means is output, and when the switching signal is output from the switching signal output means, the target drive torque determined by the other is output. Target drive torque output switching means, and an engine output operation amount capable of generating the target drive torque obtained from the target drive torque output switching means on the axle. Calculated, the engine control unit, characterized in that the engine output control amount and a, and the engine output control input calculation means for outputting to the engine output operation means. 4. The switching signal output means has an operating means for a driver to operate by designating a constant speed traveling control or a normal traveling control, and outputs a corresponding switching signal according to an operation on the operating means. The engine control device according to claim 2, wherein the engine control device outputs. 5. The switching signal output means has a judging means for judging whether to execute constant speed traveling control or normal traveling control based on an operation amount of the accelerator pedal,
The engine control device according to claim 2 or 3, wherein a corresponding switching signal is output according to the judgment of the judgment means. 6. The characteristic curve setting means stores in advance a plurality of target drive torque characteristic curves, and one target drive torque characteristic corresponding to the target vehicle speed is selected from the plurality of target drive torque characteristic curves. The engine control device according to claim 1, 2, 3, 4, or 5, wherein a curve is selected. 7. A vehicle speed change instruction means for changing the vehicle speed during constant speed traveling control, wherein the characteristic curve setting means sets the target drive torque characteristic curve once set in response to the change instruction by the vehicle speed change instruction means. 7. The engine control device according to claim 1, further comprising a characteristic curve changing means for changing the characteristic curve.