JPH0639215B2 - Vehicle running control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a traveling control device for traveling while maintaining a vehicle speed at a substantially desired set value.

(Prior Art) In recent years, a constant speed traveling device that automatically maintains the vehicle speed of a vehicle at a desired vehicle speed set by a driver has been put into practical use. This constant speed traveling device sets the vehicle speed as a target value for constant speed traveling by a set operation by the driver when the vehicle speed reaches a desired vehicle speed, and thereafter compares the set vehicle speed with the actual vehicle speed. When there is a difference between the two, the throttle valve of the engine is controlled in accordance with the difference so that the actual vehicle speed matches the set vehicle speed.

In order to carry out vehicle speed travel using such a device, it is necessary to always maintain the throttle valve opening at a predetermined opening so as to maintain the engine rotation corresponding to the set vehicle speed, but the vehicle speed is kept within a predetermined range. In consideration of the purpose of maintaining, when the vehicle speed is within the predetermined range, the clutch is disengaged to disconnect the engine from the driving force transmission to the wheels to coast the vehicle, and during this time the engine is reduced to idling rotation. By doing so, constant-speed running control with good fuel economy can be performed. For this reason, for example, in Japanese Unexamined Patent Publication No. 56-22113, a predetermined speed range is determined with reference to the set vehicle speed when a constant speed traveling condition occurs, and a lower limit is set between the upper and lower limit values in this range. A vehicle traveling control method and device have been proposed in which acceleration and coasting are repeated.

For convenience of explanation, the control for repeating the constant acceleration and the coasting to perform the constant speed traveling within the predetermined range of vehicle speed as described above is called an economy cruise, and the constant speed is controlled only by the engine rotation control like the conventional control. The control to drive the car is called auto cruise.

In this travel control, when the vehicle speed reaches the upper limit value, the clutch is disengaged and the engine throttle valve is fully closed to allow coasting, and when the vehicle speed reaches the lower limit value, the engine speed is increased to a speed corresponding to the vehicle speed, and then, Engage the clutch and gradually increase the engine speed to perform gentle acceleration until the vehicle speed reaches the upper limit. However, when performing coasting, when the engine water temperature and intake air temperature are low,
When the engine throttle valve is fully closed when the atmospheric pressure is low, there is a problem that the engine speed may be too low and engine stall may occur. In such a case, the responsiveness of the engine is also likely to deteriorate, so that even if the throttle valve is opened and closed during the transition from slow acceleration to coasting or vice versa, the engine rotation will follow the opening and closing of the throttle valve well. There is also a problem that the driving feeling may be deteriorated without doing so.

(Object of the Invention) In view of the above problems, the present invention is designed to allow the economy cruise to be carried out when the speed of the engine such as the engine water temperature and the outside air such as the intake air temperature and the atmospheric pressure are constant when the economy cruise is performed at a constant speed. It is an object of the present invention to provide a traveling control device that does not cause the above-mentioned problems by performing constant-speed traveling by automatic cruise instead of economy cruise when it is not suitable for the operation. .

(Structure of the Invention) The traveling control device of the present invention sets the upper limit value of the vehicle speed within a predetermined range near the predetermined vehicle speed signal, and controls the output of the engine until the vehicle speed reaches from the lower limit value to the upper limit value. Is used for slow acceleration, and when the vehicle speed reaches the upper limit value, the drive force transmission from the engine to the wheels is cut off and coasting is performed until the vehicle speed reaches the lower limit value, and the vehicle speed is maintained within a predetermined range. It is equipped with an economy cruise device that runs at a constant speed and an auto cruise device that runs the vehicle at a constant speed by controlling the output of the engine based on a set vehicle speed signal to maintain the vehicle speed within a predetermined range near the set vehicle speed. At least one parameter of temperature and atmospheric pressure is detected, and when the detected parameter value is equal to or less than the set value, the economy cruise prohibiting means is used to perform the economy check. It is characterized in that an automatic cruise device is operated instead of the loose device.

(Examples) Hereinafter, preferred examples of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall configuration of a traveling control device according to the present invention.

The control of the present device is performed by engaging and disengaging the clutch 10 and controlling the opening degree of the throttle valve 26 by the throttle actuator 25 based on a signal from the computer unit 30. Computer unit 3
0 is ON / OF of the cruise control switch 30a
As shown by F, the computer unit 30 receives the signal from the brake switch 2 which detects the operation of the brake pedal 1 in conjunction with the brake pedal 1 and the depression amount of the accelerator pedal 3 in conjunction with the accelerator pedal 3. A signal from the accelerator pedal position sensor 4 for detection, a signal from the engine stop detection sensor 21 for detecting whether or not the engine 20 is stopped at the distributor, and a water temperature sensor 22 for detecting the cooling water temperature of the engine 20.
Signal from the throttle position sensor 23 that detects the opening of the throttle valve 26, a signal from the intake air temperature sensor 24 that detects the intake air temperature, and an atmospheric pressure sensor 27.
From the vehicle speed sensor 16 that detects the vehicle speed by the rotation of the power transmission system on the output side of the clutch 10, and the slot actuator 25 and the electromagnetic control valve 13 are input based on these input signals.
Output an operation signal to. The electromagnetic control valve 13 controls the hydraulic pressure supply to the clutch actuation cylinder 11 to control the continuation of the clutch 10. The hydraulic pressure sent from the electric pump 15 via the accumulator 14 is controlled by the electromagnetic control valve 13 by the clutch actuation cylinder. 11 is supplied to and discharged from the rod 11a.
Is moved to the left or right in the figure so that the clutch 10 can be continued via the lever 12.

FIG. 2 is a graph showing changes with time in vehicle speed, engine rotation, etc., when traveling control is performed by the traveling control device. This graph shows changes when the cruise control switch 30a is turned on at the time point A, and with respect to the vehicle speed V at this time, the upper limit value (V + Δv) and the lower limit value (v−Δv) of the vehicle speed range in which traveling control is performed are shown. ) Is determined, and then, from this state, gentle acceleration is performed until the vehicle speed at which the engine throttle opening is gradually opened reaches the upper limit value (v + ΔV). When the vehicle speed reaches the upper limit value (time B), the clutch 10 is turned off, the throttle opening is fully closed at the same time, the engine speed is reduced to the idling speed, and the vehicle is coasted in this state. During coasting, the vehicle speed gradually decreases due to running resistance, etc. When this vehicle speed reaches the lower limit value (V-ΔV) (time C), the clutch 10 is turned on again, and the throttle opening also causes the engine rotation to reach this lower limit value. You can raise the speed to match the vehicle speed of. After that, the throttle opening is gradually opened again, and gentle acceleration is performed until the vehicle speed reaches the upper limit value.

FIG. 3 is a block diagram showing the configuration of the computer unit 30. The computer unit 30 includes a traveling switching control block 31, an economy cruise control block 32, an automatic cruise control block 33, and a normal traveling control block 3.
4, a throttle opening control block 35 and a clutch control block 36.

The travel switching control block 31 includes input lines 31a to 31.
f, 31p to 31s and output lines 31g to 31k are connected. Brake switch 2 from the input line 31a
From the clutch switch CLSW for detecting the operation of the clutch from the input line 31b, the cruise signal ACSW from the cruise switch from the input line 31c, and the cruise method switch from the input line 31d. Of the cruise method signal ECMOD, the setting signal VSSW from the vehicle speed set switch from the input line 31e, and the input line 31f.
From the vehicle speed sensor 16 to the vehicle speed signal VS, input line 3
The water temperature signal TW from the water temperature sensor 22 from 1p, the atmospheric pressure signal PAT from the atmospheric pressure sensor 27 from the input line 31q, the intake air temperature signal TIN from the intake air temperature seiser 24 from the input line 31r, and the input line 31s from the input line 31s. The select signal SLSW from the select switch is input. It should be noted that the cruise switch is a switch for switching between normal traveling and constant speed traveling, and when the cruise method switch is selected as constant speed traveling, conventional constant speed traveling (auto cruise) and slow acceleration and coasting according to the present invention are performed. Is a switch for switching between constant speed running (economy cruise) and the vehicle speed set switch is a switch for setting the vehicle speed of constant speed running, and these constitute the cruise control switch 30a in FIG. .

The select switch is a switch for selecting either economy cruise or auto cruise.

A clutch operation permission signal CLUTCH is output from the output line 31g to the clutch control block 36, and a throttle opening control permission signal THSW is output to the throttle opening control block 35 from the output line 31h. The clutch operation permission signal CLUTCH is an ON / OFF signal, and O
The clutch control signal CLB on the output line 32d from the economy cruise control block 32 is input to the clutch control block 36 only when the N signal is output. Throttle opening control permission signal T
The HSW has three kinds of signals of 1, 2, and 3. When the signal 1 is the signal THB1 from the economy cruise control block 32 via the line 32c, when the signal 2 is the automatic cruise control via the line 33c. The signal THB2 from the block 33 and the signal THB3 from the normal control block 34 are input to the throttle opening control block 35 via the line 34b when the signal is 3, respectively.

A set vehicle speed signal VSS for auto cruise is output to the auto cruise control block 33 from the output line 31i, and an upper limit value signal VSH and a lower limit value signal V of the vehicle speed for economy cruise are output from the output lines 31j and 31k.
SL is output to the economy cruise control block 32. The mode signal MOD is output from the output line 31l to the economy cruise control block 32, the automatic cruise control block 33, and the normal traveling control block 34. The mode signal MOD has three kinds of signals of 1, 2 and 3 and these three control blocks 32,
Only one of 33 and 34 is selectively activated.

The economy cruise control block 32 has an input line 32a in addition to the signals from the lines 31i and 31l.
From the engine speed signal NE from the line 32b and the vehicle speed signal VS from the line 32b are input, and based on these, the throttle control signal THB1 from the line 32c to the throttle opening control block 35 and the clutch control signal CLB from the line 32d to the clutch control block 36. Is output.

Mode signal MOD is sent to the auto cruise control block 33.
In addition, the vehicle speed signal VS is input via the line 33a, and the accelerator opening signal ACP is input via the line 33b.
The throttle control signal THB2 is output from the line 33c to the throttle opening control block 35. In addition to the mode signal MOD, the normal traveling control block 34 is supplied with the line 3
The accelerator opening signal ACP is input via 4a, and the throttle control signal THB3 is output from the line 34b to the throttle opening control block 35.

On the other hand, from the throttle opening control block 35, line 3
The operation signal is output to the throttle actuator 25 via 5a to operate the throttle valve 26, and the operation signal is output from the clutch control block 36 to the electromagnetic control valve 13 via the line 36a to output the clutch operation cylinder 11 and the lever. The clutch is actuated via 12.

The control operation of the computer unit 30 configured as described above will be described with reference to the flowchart shown below.

FIG. 4 is a flow chart showing the control in the traveling switching control block 31, which starts from step S1 and starts the 20 mS timer in step S2.
Repeat this flow every time, then step S
In 3, it is determined whether the brake signal BRSW is ON. When this is ON, that is, when the brake is depressed, the routine proceeds to steps S18 and S19, where the set vehicle speed signal VSS, the upper limit and lower limit signals VSH, VSL are set to zero, and the mode signal MOD and the throttle opening control permission signal THSW are set to 3. The clutch operation permission signal CLUTC
H is turned off and normal traveling control is performed. When the brake is not operating, the routine proceeds to step S4, where it is determined whether or not the clutch signal CLSW is ON. When it is ON, the routine proceeds to steps S18 and S19 to shift to the normal traveling control, while when it is OFF, the step S7 is performed. Go to Cruise Signal A
It is determined whether the CSW is ON. If the CSW is OFF, the process proceeds to steps S18 and S19 to shift to the normal traveling control and is turned ON.
If so, the process proceeds to step S8 to determine whether the vehicle speed is 40 km / H or less. Since both auto cruise and economy cruise are performed only when the vehicle speed is 40 km / H or more, when the vehicle speed is 40 km / H or less, the process proceeds to steps S18 and S19. When the vehicle speed is 40 km / H or more, the routine proceeds to step S9, where it is determined whether the setting signal VSSW is ON, and when it is OFF, the routine proceeds to step S1 where it is determined whether the setting vehicle speed signal VSS is greater than zero. This is because the setting signal VSSW is only a trigger signal, and if the vehicle speed setting for constant speed traveling is set when the setting signal VSSW is sent, it will be maintained thereafter even if the setting signal VSSW is turned OFF. This is because even if the setting signal VSSW is OFF, constant speed traveling is continued as long as a predetermined value is stored in the setting vehicle speed signal VSS. Therefore, when the set vehicle speed signal is zero, step S
The routine proceeds to step 18 and shifts to the normal traveling control, and when VSS> 0, the routine proceeds to step S13.

On the other hand, when the setting signal VSSW is ON, step S1
0, the actual vehicle speed VS or 100 km / H, whichever is smaller, is stored as the set vehicle speed signal VSS (this is
For safety reasons, constant speed running of 100 km / H or more is prohibited.) As the upper limit signal, the value obtained by adding 5 km / H to this set vehicle speed signal VSS is stored and set as the lower limit signal. The value obtained by subtracting 5 km / H from the vehicle speed signal VSS or 40 km / H, whichever is larger, is stored (this is because constant speed running at 40 km / H or less is not preferable from the viewpoint of stability). Next, it is confirmed whether the set vehicle speed signal VSS is 40 km / H or more. If it is 40 km / H or less, the process proceeds to step S18. If it is 40 km / H or more, the process proceeds to step S13, and the cruise method signal ECMOD is ON. To judge. This cruise method signal ECMOD is O
FF means that auto cruise is selected by the select switch. In this case, the process proceeds to step S20, the mode signal MOD is set to "2", the auto cruise control block 33 is operated, and the throttle opening control permission is given. The signal THSW is set to "2" and the clutch operation permission signal CLUTCH is turned off to perform auto cruise control. When this signal ECMOD is ON, steps S14 to S16 are performed to determine the engine water temperature (engine temperature), atmospheric pressure and suction. It is determined whether or not the temperature is below the set value, and if any one of them is below the set value, the process proceeds to step S20 to perform auto cruise control, and if all are above the set value, step S17.
Then, the mode signal MOD is set to "1" to operate the economy cruise control block 32, the throttle opening control permission signal THSW is set to "1", and the clutch operation permission signal CLUTCH is turned ON.

When step S17, S20 or S19 is completed, the process proceeds to step S21, waits for 20 mS, returns to the beginning of the flow, and thereafter, this flow is repeated every 20 mS.

FIG. 5 is a flowchart showing the control in the auto cruise control block 33, starting from step S31 and activating the 100 mS timer in step S32.
Hereinafter, this flow is repeated every 100 mS. Next, in step S33, it is determined whether or not the mode signal MOD is "2", and only when this is "2", the next step S34 is performed.
Go to. That is, this flow does not substantially operate when the mode signal MOD is other than "2". Step S
At 34, a value obtained by subtracting the vehicle speed signal VS from the set vehicle speed signal VSS, that is, a value corresponding to the difference between the set vehicle speed and the actual vehicle speed is stored as a proportional value VSP, and the vehicle speed VLAST in the previous flow from the actual vehicle speed VS (main flow Is repeated every 100 mS, the value obtained by subtracting the vehicle speed 100 mS before) is stored as the differential value VSD, and 1, 0 or -1 is stored as the integrated value VSI according to the value of the proportional value VSP. The integral value VSI is “1” when the proportional value VSP is 2 or more, and is “1” when the proportional value VSP is 2 or less and −2 or more,
When the actual vehicle speed is 2 km / H or more away from the set vehicle speed, the value becomes "-1" when it is "0" and less than -2. ing.

Next, at step S35, the proportional value VSP, the differential value VSD, and the integral value VSI are respectively given predetermined coefficients Hp and K.
After multiplying d and Ki, the calculation (VSP × Hp-VSD ×
Kd-Ki) is performed, and this is used as a throttle opening correction value T
Get as HD. In step S36, the throttle control signal THB2 is corrected by the correction value THD to obtain the throttle control signal THB2 for approaching the vehicle speed to the set vehicle speed. Further, the control signal THB2 changes from the throttle opening being fully closed (opening 0 °) to being fully opened (opening 80).
Since the signal THB2 is 80 ° or more in step S37, the signal THB2 is set to 80 °.
If it is 0 ° or less, set it to 0 °. Further, the current vehicle speed is stored as VLAST in step S38, and the accelerator opening signal AC is stored in step S39.
Throttle valve opening FN2 (ACP) calculated from P
Is stored as an actual throttle opening signal THB2B. Next, in step S40, the throttle control signal THB
The signal THB calculated in steps S34 to S37 as 2
2 or the actual throttle opening signal THB2B, whichever is larger, is selected. This is to enable the acceleration to be performed by further increasing the throttle opening degree when the driver depresses the accelerator pedal while accelerating the vehicle at a constant speed. After this, the process returns to the beginning of the flow after a lapse of 100 mS, and thereafter this flow is repeated every 100 mS.

FIG. 6 is a flow chart showing the control in the economy cruise control block 32, and this flow is step S5.
Starting from 1, in step S52 the mode memory M
Initialize with ODM set to zero, then step S5
In step 3, the 20 mS timer is started, and this flow is repeated every 20 mS. First, step S5
4, it is determined whether "1" is input to the mode signal MOD, and if it is other than "1", step S
75 and S76, the clutch control signal CLB is turned on and the throttle control signal THB1 is set to zero. Since this flow is performed when the mode signal MOD is "1", it can be said that the determination in step S54 is for safety against noise or the like.

Next, in step S58, it is determined whether or not the mode memory MODM is "1". If it is not "1", step S58
In step 59, "1" is input to the acceleration mode signal, and the lower limit engine speed signal NEM is obtained from the function FN (VSL) that calculates the engine speed for obtaining the vehicle speed lower limit value based on the lower limit value signal VSL by the gear ratio or the like. This is stored and the process proceeds to step S60. On the other hand, mode memory MODM
When is "1", the process proceeds to step S60 as it is, and the value of the mode signal MOD is stored in the mode memory MODM, which is the step S59 in the first time of this flow.
This is because it is not necessary to repeat this set as long as the mode memory MODM is 1 in the second and subsequent flows.

Next, in step S61, the acceleration mode signal ACC
Is "1". This acceleration mode signal ACC
Is a signal that distinguishes between the slow acceleration state and the inertial running state in the economy cruise. When "1", it means the slow acceleration state.
When it is "0", it indicates that the vehicle is in the inertia running mode. In addition,
In step S59, "1" is input to the acceleration mode signal ACC, because when the economy mode is selected, first, the vehicle is gently accelerated to the upper limit value of the set vehicle speed.

When the acceleration mode signal ACC is "1", step S62
Then, it is determined whether the vehicle speed signal VS is larger than the upper limit value signal VSH. If it is smaller than VSH, that is, if the vehicle speed has not yet reached the upper limit value, the current vehicle speed is changed from the relationship between the vehicle speed and the throttle opening. On the other hand, the function FN2 (VS) for obtaining the throttle opening necessary for performing the slow acceleration
From this, a predetermined throttle control signal THB1 is obtained. On the other hand, when the vehicle speed reaches the upper limit value and the vehicle speed signal VS becomes the upper limit value signal V
When it is greater than or equal to SH, steps S63 to S65 are performed, the throttle control signal THB1 is set to "0", the clutch control signal CLB is turned off, the acceleration mode signal ACC is set to "0", and inertia is set. Shift to running.

On the other hand, when it is determined in step S61 that the acceleration mode signal ACC is "0", that is, the vehicle is in the inertia running state, it is determined in step S67 whether the vehicle speed signal VS is smaller than the lower limit value signal VSL. Lower limit value signal VS
If it is larger than L, the inertia running state is continued as it is, and if it is equal to or lower than the lower limit value signal VL, the process proceeds to steps S68 to S70, and the throttle control signal THB1 is a signal α for opening the throttle opening by a predetermined amount. Is input, the difference NE1 between the engine speed signal NE at this time and the lower limit engine speed signal NEM calculated in step S59 is calculated, and it is determined whether or not the absolute value of this difference NE1 is smaller than the predetermined minute value β. Difference NE1
Is larger than β, the signal α is increased by a small amount Δα, and steps S68 to S70 are repeated. That is, the throttle valve is opened smoothly until the engine rotation reaches the rotation speed corresponding to the lower limit value of the predetermined vehicle speed. After that, steps S72 to S74 are performed and the clutch control signal is turned on to set the current vehicle speed. A function FN2 (V
A predetermined throttle control signal THB1 is obtained from S) and the acceleration mode signal is set to "1".

After the above flow, the process returns to step S53 after waiting for a 20 mS route in step S77, and this flow is repeated every 20 mS.

FIG. 7 is a flowchart showing the control in the normal traveling control block 34, starting from step S90, and in step S91 it is determined whether or not the mode signal MOD is "3". When the mode signal MOD is not "3", the control according to this flow is unnecessary, so the throttle control signal TH
This flow is finished by setting B3 to zero. On the other hand, when the mode signal MOD is "3", in step S93, the throttle control signal THB3 is obtained from the function FN2 (ACP) that obtains the necessary throttle control signal according to the accelerator opening signal ACP, and this flow is ended.

FIG. 8 is a flow chart showing the control in the throttle opening control block 35. Starting from step S101, the 20 mS timer is started in step S102, and then the throttle opening control permission signal THSW is set to “SSW” in steps S103 to S107. 1 ”,“ 2 ”,
It is determined whether it is “3” and THSW =
When 1 is set, the throttle control signal THB1 is stored as an actuator signal THOBj, when THSW = 2, THB2 is stored as an actuator signal THOBj, and when THSW = 3, THB3 is stored as an actuator signal THOBj. Next, step S1
At 08, the actuator signal THOBj is output to the actuator 25, and the throttle valve 26 is controlled to be opened / closed so that the opening degree is determined by the signal THOBj. Then, in step S109, 20 mS has elapsed, and this flow is repeated every 20 mS.

FIG. 9 is a flowchart showing the control in the clutch control block 36, and this flow starts from step S121, and in step S122, it is determined whether or not the clutch operation permission signal CLUTCH is ON, that is, whether or not it is an economy cruise. When it is not the economy cruise, the flow proceeds to step S124, the clutch actuator 13 is turned off, the clutch is connected, and the present flow ends. On the other hand, when the permission signal CLUTCH is ON,
In step S123, the clutch control signal CLB is turned on.
When the signal CLB is OFF, the vehicle is in the inertia running state and the actuator 13 is turned ON to disconnect the clutch. When the signal CLB is ON, the vehicle is in a slow acceleration state and the clutch actuator 13 is turned OFF. The clutch is connected and this flow ends.

(Effects of the Invention) As described above, according to the present invention, when the economy cruise is selected, the constant speed traveling with relatively low fuel consumption is realized by repeating the gentle acceleration and the coasting within the predetermined range of the vehicle speed. In addition, either the economy cruise or the auto cruise can be arbitrarily selected by the selection switch, and when the engine temperature, the intake temperature or the atmospheric pressure is not suitable for coasting, that is, the setting When the value is less than the value, the constant speed running is performed by the auto cruise, so that the constant speed running control can be performed without impairing the drivability of the vehicle, the driving feeling and the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a traveling control device according to the present invention, FIG. 2 is a graph showing changes with time in vehicle speed, engine rotation, etc. when traveling control is performed by the traveling control device, FIG. Is a block diagram showing a configuration of a computer unit used in the traveling control device, FIGS. 4 to 9 are flow charts showing control contents in each control block of the computer unit, and FIG. 4 is a traveling switching control block.
FIG. 5 shows an automatic cruise control block, FIG. 6 shows an economy cruise control block, FIG. 7 shows a normal travel control block, FIG. 8 shows a throttle opening control block, and FIG. 9 shows a clutch control block. 1 ... Brake pedal, 3 ... Accelerator pedal 10 ... Clutch 11 ... Clutch operation cylinder 13 ... Electromagnetic control valve, 16 ... Vehicle speed sensor 22 ... Water temperature sensor 25 ... Throttle actuator 26 ... Throttle valve 30 ... Computer unit

Claims (1)

[Claims] 1. An upper limit value and a lower limit value of a vehicle speed within a predetermined range near the set vehicle speed are set based on a set vehicle speed signal input from the outside, and the engine is operated from the lower limit value to the upper limit value. Output control of the vehicle to perform slow acceleration running, and when the vehicle speed reaches the upper limit value, the drive force transmission from the engine to the wheels is cut off to allow coasting until the vehicle speed reaches the lower limit value. An economy cruise device that maintains a constant speed within the predetermined range and the engine output is controlled based on a set vehicle speed signal input from the outside to maintain the vehicle speed within a predetermined range near the set vehicle speed and maintain a constant speed. When an auto-cruise device for traveling and at least one parameter of engine temperature, intake air temperature and atmospheric pressure are detected, and the detected parameter value is less than or equal to a set value Travel control device for a vehicle, characterized by comprising the economy cruising inhibiting means to perform constant speed running by the automatic cruise device in place of the constant-speed running by the economy cruising device.