JP2629864B2 - Control method of vehicle at constant speed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a constant speed traveling control method for a vehicle, and particularly to controlling the opening and closing of a throttle valve using a negative pressure actuator to keep the traveling speed of the vehicle at a constant value. The operation of the negative pressure actuator relates to an improvement of a constant speed traveling control method for a vehicle which is started when the set switch is returned from the on operation to the off operation.

[Prior Art] The traveling speed of a vehicle is normally controlled by the driver's operation of an accelerator pedal. However, when the vehicle continuously travels at a constant speed for a long period of time, the throttle valve is automatically opened and closed at a predetermined specified speed to automatically control the opening and closing. It is useful to drive at a constant speed, and it is mounted on a vehicle as a constant speed control device, which helps reduce the fatigue of the driver.

Normally, this kind of constant speed traveling control is performed by a control circuit comparing a designated speed with a current vehicle speed, operating a negative pressure actuator based on a comparison output of both, and opening and closing a throttle valve of an engine intake system. ing.

The negative pressure actuator may use the negative pressure of the intake system of the vehicle, or may independently incorporate a negative pressure pump.

Such constant speed traveling control is operated by a set switch provided in a driver's seat, the current vehicle speed at the time of operation of the set switch is stored in a control circuit as a set vehicle speed,
The control circuit supplies the control signal to the negative pressure actuator so as to continuously maintain the vehicle speed once determined in this way, and achieves the above-described constant speed traveling control by controlling the opening and closing of the throttle valve of the intake system. .

The set switch is turned on to prevent the constant speed traveling control from being started due to external noise or a driver's erroneous operation.
It is set so that the control is not started until it is returned to the off state next time.
For example, when the time exceeds 500 milliseconds, the off-return timing is used as a start signal of the constant speed traveling control.

Therefore, even when the set switch is turned on / off by an erroneous operation due to such fail safe, or when noise is mixed into the output side of the set switch,
Since the length is usually shorter than 500 milliseconds, it is possible to surely prevent the constant speed traveling control from being started by mistake.

By the way, conventionally, this kind of constant speed traveling control has a disadvantage that a non-negligible delay occurs when the control is started at the off-return timing of the set switch.

That is, even when the duty control signal is supplied from the control circuit, the negative pressure actuator cannot control the opening and closing of the throttle valve without delay. A delay of about 500 milliseconds occurs, and at this time, there is a problem that the vehicle speed temporarily decreases when the driver releases the accelerator pedal.

The delay of the throttle valve is remarkable particularly when the negative pressure actuator drives the accelerator pedal, and the necessary driving force from the accelerator pedal to the throttle valve, the inertia, etc. are large, so that a relatively large pressure is applied to the negative pressure actuator. Even if given, there was a considerable operating delay before the throttle valve actually started to move.

Conventionally, in order to solve this kind of drawback, there is a proposal that a control signal is supplied to a negative pressure actuator in advance during a standby period from the ON of the set switch to the return of the OFF to start pulling of a throttle valve. (Japanese Patent Application No. 61-177821 by the present applicant).

According to this conventional proposal, 70 to 80% of the target throttle valve opening is preliminarily pulled during the standby period of the set switch, whereby the throttle valve is immediately opened from the set switch off return timing. This has the advantage that control is started without delay.

[Problems to be Solved by the Invention] However, in the conventional proposed method, since the opening / closing control of the throttle valve is already started during the standby period of the set switch, when the external noise is mixed or the set switch is erroneously operated, etc. However, there is also a problem that interference from the constant-speed traveling control device is added to the driver's operation of the accelerator pedal, which causes a problem that the traveling feeling of the driver is deteriorated.

In addition, since the throttle valve has already started its movement during the standby period of the set switch, when the constant speed traveling control performs, for example, deceleration (coast) control,
In the deceleration control, there is a problem that a delay characteristic is given. On the other hand, particularly when a constant speed running is set on a downhill or the like, the vehicle speed increases more than a desired constant speed. I was

The present invention has been made in view of the above conventional problems,
An object of the present invention is to provide an improved cruise control method which reduces control delay at the start of cruise control and has no interference with a throttle valve during a standby period of a set switch.

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized in that during a standby period of a set switch, a preliminary pressure lower than a critical pressure for operating a throttle valve is applied to a negative pressure actuator. .

Such a preliminary pressure is applied during the standby period of the set switch, for example, by supplying a control signal of a predetermined duty ratio from the control circuit to the negative pressure actuator, thereby applying preliminary tension to the throttle valve from the negative pressure actuator, Is in a stationary state, but when a larger actuator driving force is applied, a state in which the actuator starts to move immediately without delay can be obtained.

Therefore, if the preliminary pressure of the negative pressure actuator is set to an optimum value from the throttle valve hysteresis characteristic inherent to the vehicle, a control method with no operation delay at the constant speed traveling start timing can be obtained.

According to the present invention, the preliminary pressure is applied only to the negative pressure actuator during the standby period of the set switch, and the throttle valve itself does not move. Therefore, the operation of the set switch is erroneously operated during the standby period. , Or in the case of noise, the preliminary pressure is removed immediately and does not cause any interference to the throttle valve control operated by the driver with the accelerator pedal.

At the time of actual constant-speed running control, at the control start timing at which the standby period has been completed, the driving force is applied to a state where the throttle valve is immediately opened and closed.
It is possible to start the constant-speed running control without delay or by sufficiently reducing the conventional delay.

The preliminary pressure application during the standby period may be performed in two stages during the standby period, or may be a predetermined constant preliminary pressure application, or may be performed at any time during the standby period. Is performed.

Embodiment A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an overall configuration diagram of a constant speed traveling control device for a vehicle to which the present invention is applied.

In FIG. 1, an opening / closing driving force from a negative pressure actuator 16 is supplied to a throttle valve 12 provided in an engine intake system 10 via a link system 14.

In the link system 14, the negative pressure actuator 16 may be directly connected to the throttle valve 12, or the accelerator pedal may be moved by the negative pressure actuator 16 and transmitted to the throttle valve 12 by the link system 14. is there.

As shown, the negative pressure actuator 16 has a negative pressure chamber 18 therein, and the movement of the diaphragm 20 biased by a spring is transmitted to the throttle valve 12.

In order to change the pressure of the negative pressure chamber 18, the negative pressure chamber 18 is
It is in communication with the atmosphere through 22 and in communication with a negative pressure pump 26 through a negative pressure port 24. The atmosphere port 22 and the negative pressure port 24
One of the valves is controlled to open and close by an on-off valve 28, and the movement of the on-off valve 28 controls the internal pressure of the negative pressure chamber 18.

To drive the on-off valve 28, a negative pressure actuator
16 is provided with a driving element 30.
When the driving transistor 32 is electromagnetically driven, the negative pressure of the negative pressure pump 26 is introduced into the negative pressure chamber 18 at the duty ratio, and a required negative pressure can be obtained.

In order to prevent the internal pressure of the negative pressure chamber 18 from becoming an abnormal pressure, the negative pressure actuator 16 is provided with a release valve 34, and by driving this release valve 34 with a release transistor 36 provided therein, In the event of an abnormality of the device, the release port 38 is forcibly opened to the atmosphere and the internal pressure of the negative pressure chamber 18 is set to the atmospheric pressure, thereby making it impossible to open the throttle valve 12 by the negative pressure actuator and preventing runaway of the device. it can.

One end of the negative pressure pump 26 is connected to the negative pressure side of the intake system 10, and when the negative pressure of the engine intake system is insufficient, the motor 40 can generate a negative pressure.

1 includes a control circuit 42 which includes a microprocessor 44, a memory 46, an output port 48, an input port 50, and a connection between these components. A data bus 52 for performing signal transmission is included.

The microprocessor 44 calculates the data processed from the input port 50 by comparing it with the table of the memory 46, and supplies a desired duty-controlled drive signal to the open / close drive transistor 32. A drive signal is supplied to the transistor 36. Further, it supplies a desired drive signal to the motor 40 of the negative pressure pump 26.

The input port 50 of the control circuit 42 includes the negative pressure pump
A signal detected by the negative pressure switch 54 is input from 26 or the negative pressure side of the intake system 10, and a signal from a set switch 56 is supplied to start constant speed traveling control.

Further, a signal is supplied from the cancel switch 58 to the input port 50 in order to end the constant speed traveling control.
The vehicle speed sensor uses the engine speed indicated by
62 detects it and takes it into the control circuit 42 from the input port 50.

Therefore, according to the constant speed traveling control device of FIG. 1, when the set switch 56 supplies the constant speed traveling start signal to the control circuit, the microprocessor 44 of the control circuit 42 stores the current vehicle speed at this time, and the transistor 32 By supplying a drive signal having a desired duty ratio to the actuator, operating the negative pressure actuator 16 and controlling the opening and closing of the throttle valve 12, the rotation of the engine 60 can be automatically controlled so as to obtain a desired vehicle speed.

The microprocessor 44 of the control circuit 42 releases the drive of the transistor 32 when the cancel signal is supplied from the cancel switch 58, and opens and closes the throttle valve 12 by releasing the negative pressure chamber 18 of the negative pressure actuator 16 to the atmosphere. Complete control.

The present invention is characterized in that at the start of constant speed traveling control by the set switch 56, a desired preliminary pressure is applied to the negative pressure actuator 16 during a standby period of the set switch 56,
This preliminary pressure is set to a critical pressure or lower that does not allow the throttle valve 16 to move.

FIG. 2 is a timing chart of the application of the preliminary pressure during the standby period of the set switch 56, and FIG.
FIG. 2 shows the flowchart of FIG.

At time t _1, the driver performs the ON operation of the set switch 56 for starting the constant speed running.

The microprocessor 44 in the control circuit 42 shown in FIG. 1 detects the ON operation of the set switch 56. In order to determine whether or not this is an erroneous operation, it is confirmed that the ON state continues for a predetermined time. Normally, the confirmation time is set to, for example, about 500 milliseconds, and if the ON duration is shorter than this, it is determined that the operation of the set switch 56 is malfunctioning, and the control circuit 42 does not start the constant speed traveling control. .

In Figure 2, time t ₃ represents the time the set switch 56 is turned off returns, this time t ₃ is the cruise control start timing of the device.

Characteristically In the present invention, the negative pressure actuator during the waiting period of the set switch 56 to the time t ₁ ~t ₃
A preliminary pressure is applied to the throttle valve 16 and this preliminary pressure is
It is set below the critical pressure to move 12.

In the embodiment of Figure 2, the application of pre-pressure application of pre-pressure is performed over the waiting period (t ₁ ~t ₃₎ the entire region of the figure, further the preliminary pressure is divided into two stages.

That is, in the initial stage from time t ₁ for example to the time t2 of about 50 ms, the negative pressure actuator 16 control circuit
A 90% control duty signal is supplied from 42 via the transistor 32, and the negative pressure is quickly supplied to the negative pressure chamber 18 of the negative pressure actuator 16. And according to the embodiment,
During the remainder of the waiting period from t ₂ (t ₃ to) the duty ratio of 40%
Is applied to maintain the pressure of the negative pressure actuator 16 at or below a predetermined critical pressure during the standby period.

In Figure 2, the internal negative pressure of the negative pressure actuator 16 is rapidly increased before the time t ₂ as shown, it maintains a substantially constant value during the subsequent waiting period.

On the other hand, the opening degree of the throttle valve 12 does not move at all during the standby period (t _{1 to} t ₃ ) because the preliminary pressure of the negative pressure actuator 16 is equal to or lower than the critical pressure. from time t ₃ is a control start timing rather quickly delayed in accordance with the pressure of the negative pressure actuator 16, or to initiate the opening and closing control with a slight delay is understood.

As is clear from the flowchart of FIG. 3, when the control of the apparatus is started, the ON operation of the set switch 56 is monitored (step 101), and when the set switch 56 is turned ON, a predetermined period thereafter, for example, 50 milliseconds During this period, negative pressure control with a 90% duty is performed (step 102), and an initial negative pressure is set to the negative pressure actuator 16.

Then, at time t ₂ has elapsed 50 milliseconds, the control circuit
The drive duty ratio from 42 is reduced to 40% output (step 103), and this preliminary pressure control is continued until the set switch 56 is turned off (step 104).

At the constant speed traveling control start timing when the set switch 56 is turned off, the control shifts to the normal control.

FIG. 4 shows the characteristics of the throttle valve 12, in which the horizontal axis represents the force generated by the negative pressure actuator 16 and the vertical axis represents the actuator stroke, that is, the actual amount of movement of the throttle valve 12.

As is clear from FIG. 4, the throttle valve 12 has a relatively large hysteresis characteristic, and this hysteresis characteristic greatly differs in relation to the negative pressure actuator 16 depending on the place where the negative pressure actuator 16 is installed.
For example, when the negative pressure actuator 16 is connected to the accelerator pedal as described above, it is understood that the hysteresis characteristic of the throttle valve 12 increases.

Also in the characteristics of FIG. 4, the throttle valve 16 hardly moves until the force generated by the negative pressure actuator 16 reaches 2 kgf, and this 2 kgf can be considered as the critical pressure for moving the throttle valve in the present embodiment.

FIG. 5 shows the characteristics of the negative pressure actuator 16, in which the horizontal axis shows the drive duty ratio applied from the control circuit 42 of the transistor 32, and the vertical axis shows the force generated by the actuator. I have.

The characteristic indicated by the solid line X in FIG. 5 indicates a state in which the vehicle is traveling on a normal horizontal road (a state in which the engine negative pressure is about 350 mmHg).
In order to obtain a critical pressure obtained from the hysteresis characteristic of FIG. 4 from the characteristic curve, for example, a preliminary pressure of 2 kgf or less, it is preferable that the drive duty ratio be about 40%. Understood.

4 and 5, it is understood that the drive duty is 44% in order to obtain, for example, an actuator generating force of 2.4 kgf.

Therefore, as shown in FIGS.
By supplying a duty signal of about 40% to the negative pressure actuator during the standby period of 6, it becomes possible to keep the throttle valve 12 in a critical state of its movement when the constant speed traveling control is started.

In the characteristic of the second set of switches 56, although the time t ₁ is on the operation timing of the set switch 56, depending on the type of vehicle, for detecting whether or not the on operation of the set switch 56 is correct on actuation May be provided, and reference character A shown by a dashed line in the characteristics of the set switch 56 in FIG. 2 indicates this ON operation confirmation characteristic. This ON operation confirmation may not be regarded as a correct ON operation until a predetermined time, for example, about 600 milliseconds has elapsed from the initial rise of the ON operation, in order to prevent malfunction due to switch chattering or the like, and even in such a method. , when applying the present invention, may be confirmed this is the period in a standby set switch 56 from time t ₁ after 600 milliseconds after a the confirmation period.

6 there is shown another embodiment of the present invention in FIG., Is similar to the Figure 2, 40% to 60% over the waiting period the whole area of the on-timing of the set switch 56 at time t ₁₁ to the off-timing t ₁₂ It is characterized by the fact that drive control with a constant duty ratio of the order is performed, and as a result, in the second embodiment, the internal negative pressure of the negative pressure actuator 16 rapidly increases from the embodiment of FIG. It does not rise, but during the waiting period the pressure rises slowly to the required pre-pressure.

FIG. 7 shows still another embodiment of the present invention.
This embodiment is characterized in that an ON operation confirmation period for removing chattering for a certain period from the initial ON operation of the set switch 56 is also used for applying the preliminary pressure.

That is, the set in FIG. 7, at time t ₂₁ the switch 56
Although the initial on operation is performed, when the chattering as in FIG occurs not easily done start accurate cruise control, in this control apparatus, the time t ₂₂
Until the ON operation confirmation period, for example 600 milliseconds approximately microprocessor exercising counter, the start of the desired cruise control at time t ₂₃ after the further elapse of time as in the prior art of 500 milliseconds from the time t ₂₂ Perform

According to this control, since both the ON operation and the OFF operation of the set switch 56 are confirmed, the set switch 56 due to chattering, malfunction or noise contamination is confirmed.
This has the advantage that the output signal can be determined very reliably.

According to the present invention, used as such on the preliminary pressure application period of operation confirmation period negative pressure actuator 16 also, according to the embodiment of FIG. 7, during the on operation confirmation period from time t ₂₁ to t ₂₂ Drives at 60% duty, and at time t
₂₂ performs until t ₂₃ is off the return timing with 40% Deti drive from which the throttle valve 12
Does not move, but the negative pressure actuator 16 has a throttle valve
Preliminary pressure set below the critical pressure immediately before moving 12 is reliably applied.

Therefore, according to the present invention, the ON operation confirmation period is:
It is not necessary to use the preliminary pressure application according to the present invention as shown in FIG. 2A, or the ON operation confirmation period can be positively used for the preliminary pressure application as shown in FIG.

In the above embodiment, the case where the engine negative pressure is a normal state of 350 mmHg has been described. However, the characteristics of the negative pressure actuator 16 shown in FIG. 5 differ depending on the level of the engine negative pressure.

That is, when the engine negative pressure is high (about 450 mmHg), the characteristic of the negative pressure actuator 16 is represented by a broken line Y in FIG.
In contrast, when the engine negative pressure is low (250 m
In the case of about mHg), the characteristic is as shown by the broken line Z. Therefore, when the engine negative pressure is high, for example, when traveling on a downhill road, the throttle valve is controlled based on the characteristic of the normal engine negative pressure indicated by the solid line X.
When the drive duty ratio that can maintain the operation critical state of 12 is set, the actuator generation force exceeds the critical pressure 2 kgf,
There is a risk that the throttle valve 12 will operate. Therefore,
As shown in FIG. 8, in the initial stage up to the time t ₂ the drive control set switch 56 is turned on has been from time t _1, for example, about 50 ms of the negative pressure actuator 16 during the waiting period of the set switch 56 Control is performed at a drive duty ratio of 90% (this is the same as the embodiment of FIG. 2). Then, between time t ₂ of t ₃ Wait the remaining waiting period to control the negative pressure actuator 16 a driving duty ratio 0%.

By such control based on the drive duty ratio,
For example, even when the vehicle is traveling on a downhill road and the engine negative pressure is high, a preliminary pressure equal to or lower than the critical pressure for operating the throttle valve 12 can be applied.

[Effects of the Invention] As described above, according to the present invention, a predetermined preliminary pressure, that is, a preliminary pressure equal to or lower than the critical pressure for driving the throttle valve, is applied to the negative pressure actuator using the standby period of the set switch. Therefore, at the constant-speed cruise control start timing when the set switch standby period is completed, the negative pressure actuator immediately prepares to move the throttle valve, so that the constant-speed cruise control has no delay or the responsiveness with reduced delay Can be performed.

On the other hand, in the present invention, the driving force from the negative pressure actuator is not applied to the throttle valve during the standby period. There is an advantage that it does not adversely affect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a device to which a constant-speed traveling control method according to the present invention is applied, FIG. 2 is a timing chart for explaining the application of a negative pressure actuator preliminary pressure in FIG. 1, and FIG. FIG. 2 is a flow chart of FIG. 2, FIG. 4 is a characteristic diagram of a throttle valve used in the present invention, FIG. 5 is a characteristic diagram of a negative pressure actuator used in the present invention, and FIGS. FIG. 9 is a timing chart illustrating another control method. 10 Engine intake system 12 Throttle valve 16 Negative pressure actuator 42 Control circuit 56 Set switch

Claims (1)

(57) [Claims] An opening / closing control of a throttle valve of an engine intake system is controlled by a negative pressure actuator to automatically maintain a predetermined traveling speed, and the opening / closing control of the throttle valve is started at an off-return timing of an on-set set switch. In the constant-speed traveling control method for a vehicle, a pre-pressure that does not reach a critical pressure for operating the throttle valve during a standby period from the ON operation of the set switch to the return to the OFF state is given to the negative pressure actuator, and the set switch is turned off. A constant speed traveling control method for a vehicle, characterized in that an operation delay in the vehicle is reduced.