JPH08295155A - Constant running device for vehicle - Google Patents

Abstract

PURPOSE: To restore to a set car speed smoothly without generating an undershoot after a tentative acceleration is finished, by feeding a specific operating pressure to an actuator, when the operating pressure to the actuator is reduced by the finishing of the tentative acceleration, and the throttle opening is reduced. CONSTITUTION: In a control unit 1, the signals of a car speed sensor 8, a throttle sensor 9, a crank angle sensor 13, and the like are read, in an engine operating condition. When a set switch 3 is ON, the present actual car speed is stored as a car speed instruction value, and the target driving force and the target throttle opening of an engine are operated depending on the car speed instruction value. When a tentative acceleration condition by the operation of a driver is detected, the operating pressure to an actuator 30 is reduced as well as the throttle opening control to the car speed instruction value is stopped. When it is detected that the acceleration request is finished, the operating pressure to the actuator 30 is fed to make the throttle opening in a specific opening smaller than the throttle opening before the tentative acceleration is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a vehicle constant-speed traveling device that keeps the traveling speed of a vehicle constant.

[0002]

2. Description of the Related Art A constant speed steering device controls a throttle opening of an engine so that a traveling speed of a vehicle is maintained at a speed designated by a driver. This is because the vehicle speed at that time is generally stored as a vehicle speed command value when the driver turns on a switch for instructing constant speed driving when the vehicle speed reaches the desired vehicle speed by operating the accelerator. Regardless of this, the throttle opening is feedback-controlled so that the actual vehicle speed matches the command value.

Such constant speed traveling control is normally canceled by the driver performing a cancel operation or a brake operation, but a temporary acceleration operation for overtaking or the like is possible. Therefore, while the driver is depressing the accelerator pedal, the engine output is increased by the throttle opening according to the accelerator operation, and after the accelerator pedal has been depressed, the vehicle speed before acceleration is restored to a constant value. There is one that restarts the speed control. (Publication of this type of constant speed traveling device includes, for example,
See 1-212621. )

[0004]

By the way, in such a constant speed control device using a negative pressure type actuator as a means for driving the opening and closing of the throttle, a strong operating negative pressure from a negative pressure pump or the like supplied to the actuator is used. A solenoid valve for controlling the pressure is provided, and the strength of the negative pressure, that is, the opening of the throttle is controlled by changing the opening / closing cycle of the solenoid valve according to the duty ratio of the drive pulse signal. .

However, in such an actuator using the negative pressure type actuator, during the above-described temporary acceleration, the actuator opening is changed so that the accelerator opening can be changed in the entire range from fully open to fully closed according to the operation of the driver. Is opened to the atmosphere. As a result, as shown in FIG. 8, when the temporary acceleration ends and the constant speed control is resumed, the rise of the operating negative pressure in the actuator is delayed, and the vehicle speed is greatly under There is a problem of shooting. That is, when the driver releases the accelerator pedal, the accelerator opening once becomes the fully closed position, the vehicle starts decelerating, and eventually when the vehicle speed decreases to around the set vehicle speed before acceleration, the accelerator opening corresponds to the set vehicle speed. The throttle opening command is issued to return to the specified position, but even if this opening command is issued, sufficient negative pressure is immediately supplied to drive the actuator to the position equivalent to the command opening. Since this is not possible, the undershoot occurs with a corresponding delay in the rise of the accelerator opening from the fully closed position.

Although the above-mentioned publicly known document discloses a method for improving the convergence of the vehicle speed by adjusting the control gain after acceleration, the opening of the solenoid valve is delayed while the operating pressure is delayed. Since the actuator cannot follow the change, such a control method cannot solve the problem of undershoot inherent in the pressure-responsive actuator.

The present invention has been made in view of these problems, and in a constant speed traveling device equipped with a pressure-responsive throttle actuator, the vehicle speed can be smoothly returned to the set vehicle speed without causing undershoot after temporary acceleration. The purpose is to let.

The present invention is not limited to an engine having a throttle valve, but can be applied to, for example, a diesel engine whose output is controlled by the position of the control lever of a fuel injection pump. The output adjustment unit of is referred to as a throttle.

[0009]

A first aspect of the present invention, as shown in FIG. 9, is an actuator A for increasing or decreasing the throttle opening of an engine in response to an operating pressure supplied from a pressure source; Valve means B for adjusting the pressure, throttle opening control means C for controlling the throttle opening by driving the valve means B so that the vehicle speed command value set by the driver and the actual vehicle speed match, Temporary acceleration detection means D for detecting a temporary acceleration state by a human operation, and temporary acceleration control means for interrupting the throttle opening control to the vehicle speed command value and reducing the working pressure to the actuator when the temporary acceleration is detected. E, an acceleration request end detection means F for detecting the end of the temporary acceleration request, and a predetermined throttle opening smaller than the throttle opening before the start of the temporary acceleration when the acceleration request end is detected. Providing an actuation pressure retaining means G for supplying an actuator operating pressure to the.

According to a second aspect of the present invention, the temporary acceleration detecting means of the above invention detects the temporary acceleration state because the throttle opening is a predetermined value or more and the deviation between the actual vehicle speed and the vehicle speed command value is a predetermined value or more. I shall.

According to a third aspect of the present invention, the temporary acceleration detecting means of the first aspect of the present invention detects the temporary acceleration state because the throttle opening is a predetermined value or more and the running resistance change estimated from the vehicle speed is a predetermined value or more. It shall be.

According to a fourth aspect of the present invention, the operating pressure holding means of each of the above aspects increases the throttle opening from the fully closed position to a predetermined opening after the temporary acceleration request is completed, and then again closes the throttle opening fully. It shall be configured to hold the working pressure when it is returned.

In a fifth aspect of the present invention, the operating pressure holding means of the first to third aspects of the present invention provides an operating pressure when the throttle opening is increased from the fully closed position to a predetermined opening after the completion of the temporary acceleration request. It shall be configured to hold.

[0014]

In the first aspect of the invention, the operating pressure of the actuator is reduced by the end of the temporary acceleration request, and the throttle opening is reduced to, for example, the fully closed position. As a result, the vehicle speed that has been increasing due to the acceleration request up to that point begins to decrease, but during that time, a predetermined operating pressure is supplied to the actuator that has been in a depressurized state due to the acceleration request. As a result, there is no response delay of the operating pressure with respect to the vehicle speed command value at the time of shifting to the constant speed traveling again, and the actuator operates promptly so that undershoot does not occur.

In the second aspect of the invention, the temporary acceleration state is detected based on the detected values of the throttle opening and the vehicle speed used in the constant speed traveling control, so that the temporary acceleration detecting means can be easily constructed.

According to the third aspect of the invention, the temporary acceleration state is determined not only from the throttle opening but also from the change in the running resistance that is highly correlated with the vehicle speed at that time, so that more accurate temporary acceleration can be detected.

According to the fourth aspect of the invention, the throttle opening which is fully closed at the end of the acceleration request at the time of temporary acceleration can be maintained in the fully closed state while maintaining the operating pressure. It can be performed by making maximum use of engine braking torque.

In the fifth aspect of the present invention, the operating pressure is only applied from the state where the throttle opening is fully closed with the completion of the acceleration request at the time of temporary acceleration, so that the control is simple and after the acceleration. Even under the condition that the vehicle speed and the set vehicle speed are close to each other and the vehicle returns to the initial set vehicle speed in a relatively short time after the end of the acceleration request, the high responsiveness that can cope with this can be obtained.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a constant-speed traveling control unit having the functions of the respective means of the control system of the present invention, and a microcomputer 10 having a CPU, ROM, RAM, various interfaces and various timers.
And the throttle actuator drive circuit 11 as a main component. Reference numeral 12 is a fail-safe power cutoff circuit, which cuts off the power to interrupt the constant speed control when an abnormality occurs in the control system, and the throttle opening is controlled according to the accelerator operation by the driver. It is intended to

Reference numerals 2 to 7 are switches operated by the driver, and the control unit 1 determines whether to start or cancel the constant speed traveling control according to the operation of these switches. 2 is a main switch for constant speed running control, a set switch 3 is for starting constant speed running control and setting a vehicle speed, and an acceleration switch 4 and a deceleration switch 5 command increase and decrease of a target vehicle speed, respectively. However, the cancel switch 6 and the brake switch 7 release the constant speed traveling control.

Various sensors for detecting the driving state of the vehicle are connected to the control unit 1, and the vehicle speed sensor 8 is
The control unit 1 calculates the actual vehicle speed by transmitting a pulse signal corresponding to the actual vehicle speed and counting the pulses. The vehicle speed sensor 8 is composed of, for example, a magnetic sensor and the like, and although not shown, detects the rotation of a permanent magnet connected to the speedometer cable from the opening / closing of the reed switch, and generates a pulse accompanying the opening / closing of the reed switch. The signal indicates the actual vehicle speed.

The throttle sensor 9 is composed of a potentiometer or the like and sends out a signal corresponding to the actual throttle opening. The control unit 1 and the throttle drive circuit 11 control the drive of the throttle actuator 30 based on this throttle opening. It is used for estimation calculation of running resistance, which will be described later. Further, the crank angle sensor 13 sends out the engine speed Ne.

A throttle for controlling the amount of intake air is provided in the intake passage of the engine, and this throttle is driven by a negative pressure type throttle actuator 30 which responds to a command from the control unit 1. The negative pressure type throttle actuator 30 2 is provided with a negative pressure pump 31 and a solenoid valve 32 as a valve means for atmospheric opening control, and the throttle drive circuit 11 responds to a target throttle opening calculated by the controller 1 and an actual throttle opening. Output the pulse width as a duty signal, and the negative pressure pump 3 driven according to this pulse width
1, the negative pressure type throttle actuator 30 is expanded / contracted according to the negative pressure generated by the solenoid valve 32 and the solenoid valve 32, and the throttle opening is controlled via the accelerator wire.

3 to 4 are flow charts showing an example of the control performed by the control unit 1, which is executed at predetermined time intervals, for example, every 50 msec by a timer interrupt or the like, and FIG. 3 maintains the target vehicle speed. FIG. 4 shows a routine for executing throttle servo control for executing the above, and FIG. 4 shows a routine for executing temporary acceleration control. Details will be described below with reference to these flow charts.

First, in step S1, the vehicle speed sensor 8,
The signals of the throttle sensor 9 and the crank angle sensor 13 are read, and the average value of the vehicle speeds counted during the predetermined time is set as the actual vehicle speed Vsp based on the signals counted during the predetermined time (50 msec). The average value of the engine speed is calculated as the engine speed Ne, and the output of the throttle sensor 9 is A / D converted to measure the actual throttle opening Tvo.

In step S2, the cancel switch 6
Also, it is determined whether one of the brake switch 7 is ON, and it is determined whether to continue (start) or cancel the constant speed traveling control,
If it is released, the process proceeds to step S8 and thereafter, while if it is continued, the process proceeds to step S3.

In step S3, it is determined whether or not the set switch 3 is on, and if it is on, the vehicle speed command value Vspr is set as the target vehicle speed. Therefore, the process proceeds to step S4. Go to step S7.

In step S4, the current actual vehicle speed Vsp is stored as the vehicle speed command value Vspr, and in steps S5 to S6, the constant speed traveling control flag indicating 1 is being controlled.
Power-off circuit for fail-safe 1
2 is ready for operation.

If the set switch 3 is off in step S3, the processes in and after step S7 are performed, and constant speed running control and acceleration control or deceleration control based on the vehicle speed command value Vspr set up to the previous time are performed. Be seen.

In step S7, it is determined whether or not the constant speed traveling control flag indicating that the constant speed traveling control is being executed is set state = 1. If it is in the set state, the processing proceeds to step S10 and the subsequent steps, but not. In that case, the process proceeds to step S8.

In steps S10 to S15, in order to match the actual vehicle speed Vsp with the vehicle speed command value Vspr, the target driving force For and the target throttle opening of the engine are used by using the model matching method and the approximate zeroing method which are linear control methods. Calculate Tvor.

First, the outline of the compensator for performing the feedback control of the vehicle speed will be described.

The transfer characteristic of the controlled object is represented by the pulse transfer function P
With (z ^-1 ), the compensator is as shown in FIG.

In FIG. 5, z is a delay calculation element,
When multiplied by z ⁻¹ , the value becomes one sample period before. Also,
C1 (z ^-1 ) and C2 (z ^-1 ) are disturbance estimators based on the approximate zeroing method and suppress the influence of disturbance and modeling errors.

C3 (z ^-1 ) is a compensator based on the model matching method, and the response characteristic of the controlled object when the target vehicle speed is input and the actual vehicle speed is output has a predetermined first-order delay and dead time. It is set so as to match the characteristics of the reference model H (z ⁻¹ ).

[0037] Enter the target acceleration, when put a portion of the controlled object and outputs the actual vehicle speed Vsp, P (z ^-1) integral element shown in the following formula P1 (z ^-1) and dead time element P2 (z ^- It can be set as the product of ¹ ) = z ^-2 . However, T is the sampling period (5
0 msec).

P1 (z ^-1 ) = T · z ^-1 / (1-z ^-1 ) At this time, C1 (Z ^-1 ) and C2 (Z ^-1 ) are as follows.

C1 (Z ⁻¹ ) = (1−γ) · z ⁻¹ / (1−γ · z ⁻¹ ) (low-pass filter with time constant Tb) C2 (Z ⁻¹ ) = (1−γ) · (1-z ^-1 ) / T ・ (1-γ ・
z ⁻¹ ) (C2 = C1 / P1) where γ = exp (−T / tb).

If the dead time of the controlled object (= ineffective time of the negative pressure type throttle actuator 30) is ignored and the reference model is a first-order low-pass filter with a time constant ta, C3
Is the following constant.

C3 = K = {1-exp (-T / ta)} / T Based on the above, the following calculation is performed. However, the data y (k-1) indicates the data y (k) one sample period before.

Y2 (k) = γ · y2 (k-1) + (1-
γ) ・ y1 (k-1) y3 (k) = γ ・ y3 (k-1) + (1-γ) / T ・ Vsp
(K)-(1-γ) / T · Vsp (k-1) y1 (k) = K · {Vspr (k) -Vsp (k)}-y3
(K) + y2 (k-2) Here, y1 (k) is the target acceleration, and the target driving force For is calculated as follows by multiplying by the basic weight M of the vehicle.

For (k) = y1 (k) M In step S10, from the target driving force For, first,
The target engine torque Ter is calculated by the following equation. However, Gm is the reduction ratio selected in the transmission, Gf is the final reduction ratio of the drive system after the transmission, and Rt is the effective radius of the drive wheels.

Ter = (For · Rt) / (Gm · Gf) Further, as shown in FIG. 6, the target is calculated from the engine speed Ne and the target engine torque Ter by using a preset non-linear data map of the engine. Throttle opening Tvo
Find r.

In the throttle servo control for running at a constant speed, normally, in steps S32 to S33 of FIG. 4, the negative pressure pump 31 and the solenoid valve of the negative pressure type throttle actuator 30 are set in accordance with the target throttle opening Tvor thus obtained. The duty ratios Dvac and Dvent of 32 are calculated by a control method such as PID control, and the duty ratio is calculated according to a deviation Δ of the throttle opening (target throttle opening Tvor−actual throttle opening Tvo) to obtain a negative pressure. The duty ratio is set in each output register to the pump 31 and the solenoid valve 32, and the negative pressure type throttle actuator 30 is driven.

In step S2, when the cancel switch 6 is operated to release the constant speed traveling control flag, the constant speed traveling control flag and the target throttle opening Tvor are reset and the power is supplied in steps S8 to S9. After the shutoff circuit 12 is deactivated, the control loop returns to the beginning.

In the normal constant speed control, the traveling speed of the vehicle is kept constant by repeating such throttle servo control. However, if the driver depresses the accelerator pedal during the constant speed control, the throttle speed is reduced. The servo control is temporarily interrupted and the temporary acceleration control shown in FIG. 4 is executed.

The outline of the temporary acceleration control of this embodiment will be first described. In this control, when it is detected that a temporary acceleration state is entered from a predetermined operating state signal, the driver is based on the subsequent change in the actual accelerator opening. After detecting the completion of the acceleration request of, the operating negative pressure is supplied to the throttle actuator 30 so that the throttle opening slightly increases from the fully closed position, and then this operating negative pressure is applied to the accelerator opening fully closed. While maintaining a degree equivalent to the vicinity, wait for return to constant speed control by throttle servo control (Fig. 7).
reference). As a result, when returning from the temporary acceleration state to the constant speed control state, an appropriate negative pressure is secured in the throttle actuator 30 to enhance the control responsiveness of the throttle opening toward the target vehicle speed.

In detail, first, steps S16 to S in FIG.
At 19, the temporary acceleration state is determined and the temporary acceleration detection flag is set. In this case, when the actual throttle opening is 15 ° or more and the deviation between the actual vehicle speed and the target vehicle speed is 5 km / h or more, the temporary acceleration state is determined and the temporary acceleration detection flag is set to 1. As a result, in the next control cycle, in step S16, step S2 for temporary acceleration control is performed.
It will move to processing after 0. Needless to say, when the temporary acceleration condition is not satisfied, the constant speed control by the throttle servo control described above is continued. In this case, the temporary acceleration condition is detected from the actual throttle opening and the vehicle speed deviation, but in addition to this, for example, in addition to changes in the accelerator opening and the actual throttle opening, changes in running resistance estimated from the vehicle speed are also possible. It is also possible to detect based on such as.

Next, when the temporary acceleration state is detected, it is checked in step S20 whether the target throttle opening Tvor is zero. Although not shown, the target throttle opening degree is set to zero in order to bring the operating negative pressure to the throttle actuator 30 to the atmospheric level when shifting to the temporary acceleration state. On the other hand, when returning to the constant speed control, for example, when the actual vehicle speed approaches the target vehicle speed immediately before shifting to temporary acceleration, the target throttle opening degree is controlled to control the accelerator opening degree corresponding to the target vehicle speed. T
Since we will set vor to a value greater than zero,
As a result, it is determined that the condition is one for ending the temporary acceleration control. If it is determined that the temporary acceleration control is completed, all flags indicating various control conditions during the temporary control are cleared in step S21 to return to the throttle servo control.

If the target throttle opening Tvor is zero, then after the actual throttle opening Tvo is zero, that is, the throttle is fully closed by the processing of steps S22 to S27, a little after the fully closed position. Feedforward control (“FF control” in the flow chart) to the extent that the throttle opens
Is abbreviated. Hereinafter, the same abbreviations are used in this description. ) To supply an operating negative pressure to the throttle actuator 30. That is, first, in the processing of step S22 and thereafter, the opening direction FF control flag is set to 1 on condition that the actual throttle opening Tvo is zero, and the opening direction FF control is started. This is performed, for example, by applying a drive signal having the following duty to the throttle actuator 30.

Dvac = 50%, Dvent = 100% However, in this case, the larger the ratio of Dvac, the more negative pressure increases, and the larger the ratio of Dvac, the smaller the amount of dilution by the atmosphere. Therefore, in this case, with the solenoid valve 32 blocking the atmosphere, the negative pressure pump 31
Some operating negative pressure from will be supplied (Fig. 2
reference). As a result, the throttle starts reopening from the fully closed position.

Next, since the actual throttle opening Tvo becomes larger than zero by performing the control for opening the throttle opening from the fully closed position in this way, the subsequent step S28 is performed.
After setting the closing direction FF control flag to 1, the F direction in the closing direction from step S29 to S30 from the next control cycle.
F control is performed. The control duty of each signal at this time is as follows, for example.

Dvac = 0%, Dvent = 50% That is, the introduction of the negative pressure from the negative pressure pump 31 is cut off, the solenoid valve 32 is slightly opened to introduce the atmosphere, and the throttle starts to close again. .

When the throttle opening returns to zero as a result of this closing direction FF control, the negative pressure holding control is next performed in accordance with the flow of processing to steps S29 to S31. This is done by giving the following duty to each signal.

Dvac = 0%, Dvent = 100% As a result, the negative pressure pump 31 and the solenoid valve 32 are fully closed. At this time, the throttle opening is zero, but the actuator 30 has a negative pressure to some extent. Is stored.

FIG. 7 shows such temporary acceleration control and the control characteristics of the vehicle speed resulting therefrom. As shown in the figure, when the throttle is in the fully closed state a due to the driver's accelerator release operation during temporary acceleration, first the throttle is slightly opened by the opening direction FF control b and then by the closing direction FF control c. After returning to the fully closed position again, the negative pressure holding control d
Holds the operating negative pressure in that state.

In this way, during the temporary acceleration, while the driver returns the accelerator and is in the deceleration state, the throttle actuator 30 is in the state in which the negative pressure is stored while being controlled to the fully closed position. Therefore, when the actual vehicle speed approaches the vehicle speed command value and returns to the throttle servo control again, the negative operating pressure in the actuator 30 rises promptly and the throttle opening follows the command value with good response. It is possible. Therefore, the actual vehicle speed does not cause undershoot and converges favorably to the command value as shown in the figure.

By the way, in this embodiment, the negative pressure holding control of the actuator 30 is performed based on the throttle opening, and the negative pressure when the valve is once opened from the fully closed state to the fully closed state is used as the held negative pressure. Not limited to this, for example, the negative pressure at a position slightly opened from the fully closed state or the negative pressure after a lapse of a certain time from the supply may be maintained. Alternatively, the negative pressure to be held may be detected, and the negative pressure holding control may be performed based on the detected negative pressure. Further, in the embodiment, the negative pressure is held at the throttle fully closed position, but the throttle opening for holding the negative pressure is an opening that can be appropriately decelerated to the vehicle speed command value after temporary acceleration, that is, immediately before the start of temporary acceleration. If the throttle opening is smaller than the throttle opening of the above, the throttle may not be fully closed.

[0060]

As described above, according to the first aspect of the invention, the response delay of the operating pressure with respect to the vehicle speed command value when the vehicle temporarily transits from the temporarily accelerated state to the constant speed traveling is eliminated, and the actuator is promptly operated. As a result, undershoot does not occur and good vehicle speed control characteristics can be obtained.

Further, according to the second invention, the temporary acceleration detecting means can be easily constructed, and according to the third invention, the temporary acceleration can be detected with higher accuracy.

According to the fourth aspect of the invention, since the throttle opening can be maintained in the fully closed state while maintaining the working pressure, deceleration after temporary acceleration can be performed by making maximum use of the engine braking torque. , Sufficient deceleration performance can be obtained.

According to the fifth aspect of the present invention, since the control of maintaining the operating pressure after the end of the temporary acceleration request is simple, the vehicle speed after acceleration and the set vehicle speed are close to each other, and a relatively short time is required after the end of the acceleration request. Therefore, even under the condition that the vehicle speed returns to the initial set vehicle speed, a high responsiveness that can deal with this can be obtained, and therefore the convergence to the set vehicle speed under such conditions can be enhanced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a constant speed traveling control device showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a negative pressure type throttle actuator.

FIG. 3 is a flowchart showing the control contents of the embodiment.

FIG. 4 is a flowchart showing the control contents of the embodiment.

FIG. 5 is a configuration diagram of a feedback control compensator.

FIG. 6 is a map diagram showing a non-linear characteristic of the engine.

FIG. 7 is a characteristic diagram showing vehicle speed control characteristics after temporary acceleration according to the present invention.

FIG. 8 is a characteristic diagram showing a vehicle speed control characteristic after temporary acceleration according to a conventional technique.

FIG. 9 is a block diagram showing a configuration concept of the present invention.

[Explanation of symbols]

 A actuator B valve means C throttle opening control means D temporary acceleration detection means E temporary acceleration control means F acceleration request end detection means G working pressure holding means 1 constant speed traveling control unit 30 negative pressure type throttle actuator 31 negative pressure pump 32 solenoid valve

Claims (5)

[Claims] 1. An actuator for increasing / decreasing a throttle opening of an engine in response to an operating pressure supplied from a pressure source, valve means for adjusting the operating pressure, a vehicle speed command value set by a driver and an actual vehicle. When a temporary acceleration is detected, a throttle opening control means for controlling the throttle opening by driving the valve means so that the speed coincides, a temporary acceleration detecting means for detecting a temporary acceleration state by a driver's operation, In addition, the temporary acceleration control means for interrupting the throttle opening control to the vehicle speed command value and reducing the operating pressure to the actuator, the acceleration request end detecting means for detecting the end of the temporary acceleration request, and the acceleration request end detection time. The operating pressure holding means for supplying the actuator operating pressure to a predetermined throttle opening smaller than the throttle opening before the start of temporary acceleration is provided. Characteristic vehicle constant speed traveling device. 2. The temporary acceleration detecting means detects the temporary acceleration state because the throttle opening is a predetermined value or more and the deviation between the actual vehicle speed and the vehicle speed command value is a predetermined value or more. 1. The vehicle constant speed traveling device according to 1. 3. The temporary acceleration detecting means detects the temporary acceleration state when the throttle opening is equal to or larger than a predetermined value and the running resistance change estimated from the vehicle speed is equal to or larger than a predetermined value. A constant-speed traveling device for a vehicle as described. 4. The working pressure holding means holds the working pressure when the throttle opening is once increased from the fully closed position to a predetermined opening after the completion of the temporary acceleration request, and then the throttle opening is returned to the fully closed again. The constant speed traveling device for a vehicle according to any one of claims 1 to 3, wherein 5. The working pressure holding means holds the working pressure when the throttle opening is increased from the fully closed position to a predetermined opening after the completion of the temporary acceleration request. 4. The constant speed traveling device for a vehicle according to claim 3.