JP2000095097A - Negative pressure control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain deterioration of fuel consumption rate to minimum, by controlling a control mechanism portion according to a control map so as to further raise absolute value of negative pressure in an intake pipe, when an absolute value of output value of a negative pressure sensor is lower than a second threshold lower than a first threshold. SOLUTION: A vacuum booster 1 is connected with an intake pipe 5 of an engine, and negative pressure is supplied from the intake pipe 5 of the engine to a negative pressure sensor 2. For raising absolute value of the negative pressure, an electronic throttle valve constituting a control mechanism portion 4 is controlled so as to closed by a given value. When a negative pressure value is low, for recovering the negative pressure, a controller 3 controls supply air amount according to a control map under an ideal air-fuel ratio followed by some deterioration of fuel consumption. When the negative pressure value is high, because the negative pressure is sufficiently recovered, lean air-fuel ratio control is performed for saving the fuel consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure control device for supplying a negative pressure to a vacuum booster, and more particularly to a negative pressure control device for an engine in which steady operation is performed with an intake pipe pressure close to atmospheric pressure. About.

[0002]

2. Description of the Related Art In a conventional engine, a so-called ideal air-fuel ratio control in which an air-fuel mixture in which fuel and air are uniformly mixed at a fixed ratio (approximately 1: 14.6) is sucked and burned to generate an output is generated. Had gone. However, in recent years, engines for performing variable air-fuel ratio control such as a so-called direct injection engine (hereinafter referred to as a direct injection engine) have been put to practical use for the purpose of improving fuel efficiency. With the direct injection engine, in the normal running state, after opening the electronic throttle valve and inhaling a large amount of air, it supplies the necessary fuel only near the spark plug and performs so-called lean air-fuel ratio control to perform lean combustion,
The air-fuel ratio is switched only under predetermined conditions to perform ideal air-fuel ratio control.

[0003] However, when a direct injection engine or the like is used, it is difficult for a sufficient negative pressure to be generated in the intake pipe in the lean air-fuel ratio control state, and the negative pressure in the intake pipe is led to a vacuum booster to use this negative pressure. There is a problem that the brake booster that assists the braking force of the vehicle is difficult to work.

In order to solve this problem, for example, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 164840 discloses a technique in which when a negative pressure in an intake pipe falls below a predetermined threshold value, the throttle valve is closed by a predetermined amount to increase the negative pressure in the intake pipe downstream of the throttle valve. ing.

According to the manual of the '96 Corona Premio, during braking, in order to secure a sufficient negative pressure, the control is switched from the lean air-fuel ratio control to the ideal air-fuel ratio control and the engine generated at the time of the switching. In order to avoid a sudden change in torque, there is disclosed a technique in which control is performed so that response is delayed and switching is performed smoothly.

[0006]

However, the manner in which the driver depresses the brake pedal, that is, the amount of negative pressure consumed by the vacuum booster, varies, and the brake operation is affected by the operation of the diaphragm built in the vacuum booster. The negative pressure in the vacuum booster decreases each time the ON / OFF operation is performed. Therefore, especially when the brake is frequently turned ON / OFF in a short time, the negative pressure reduction amount becomes larger than usual. In such a case, as described in the above-mentioned publication, even if an attempt is made to perform the negative pressure recovery control using only one threshold value, the negative pressure replenishment does not follow, and the braking force of the brake decreases. was there. In this case, as described in the aforementioned Corona Premio manual, if control for delaying response is added when switching from the lean air-fuel ratio control to the ideal air-fuel ratio control, the negative pressure replenishment will no longer follow.

[0007] In addition, the negative pressure may be sufficiently secured during the brake braking, and the negative pressure may not be replenished in some cases. As described in the aforementioned Corona Premio manual, the negative pressure can be secured during the brake braking. If the control is always performed to switch to the ideal air-fuel ratio control in which the fuel efficiency is deteriorated, the control is excessively switched to the ideal air-fuel ratio control, and there is a problem that the fuel efficiency is deteriorated.

The present invention has been made to solve the above-mentioned problem, and provides an engine negative pressure control device capable of generating a sufficient braking force under any conditions while minimizing deterioration of fuel economy. The purpose is to:

[0009]

In order to achieve the above object, the invention according to claim 1 provides a vacuum booster for introducing a negative pressure from an intake pipe of an engine to assist a braking force of a vehicle, and the vacuum booster. A negative pressure sensor that detects a negative pressure in the air, a control mechanism that controls the negative pressure in the intake pipe, and a controller that controls the control mechanism in accordance with at least the output of the negative pressure sensor, The controller increases the absolute value of the negative pressure in the intake pipe by a predetermined amount when the absolute value of the output value of the negative pressure sensor falls below a first threshold value, When the absolute value of the output value has fallen below a second threshold value smaller than the first threshold value, the control mechanism follows a control map that further increases the absolute value of the negative pressure in the intake pipe. Control the department It was collected by negative pressure control apparatus for an engine according to claim.

As described above, the controller that controls the control mechanism in accordance with the output of the negative pressure sensor determines the absolute value of the negative pressure in the intake pipe by using the first threshold value and the second threshold value of the negative pressure value of the engine intake system. The brake is frequently turned on in a short time by controlling according to a control map having two thresholds with a threshold.
Even if the negative pressure drop amount is large, such as when it is turned off, negative pressure replenishment follows, and a sufficient braking force can be stably secured.

Specifically, for example, the negative pressure in the intake pipe is controlled according to a control map as shown in FIG. In FIG. 5, a first threshold value PH of the negative pressure value is a negative pressure value at which the control of the supply air amount is started. When the absolute value of the negative pressure is larger than PH, the negative pressure is sufficiently secured. The amount of intake air supplied to the engine intake system is not controlled, and has a constant value K0. If the absolute value of the negative pressure has decreased to PH or less, the supply air amount is reduced by a predetermined amount and set to K1. In order to reduce the supply air amount by a predetermined amount, for example, the control may be performed so that an electronic throttle valve constituting the control mechanism is closed by a predetermined amount. Further, when the absolute value of the negative pressure has decreased and has decreased to the second threshold value PH 'or less, fine control is possible when a linear sensor is used as the negative pressure sensor. As shown in FIG. 5, the supply air amount is further reduced in a linear function according to the negative pressure value, and the followability of the negative pressure is further improved. On the other hand, when the absolute value of the negative pressure is lower than or equal to the second threshold value PH ′ and a so-called multi-contact switch is used as the negative pressure sensor, as shown in FIG. The amount is reduced by a predetermined amount from K1 to K2 to improve the followability of the negative pressure. Here, in the invention described in the official gazette shown in the related art, even when the absolute value of the negative pressure is reduced to PH 'or less, the supply air amount is not reduced to the predetermined value K1 or less, The followability of the negative pressure may be delayed.

Further, according to the present invention, even during braking, if the negative pressure is sufficiently ensured, the control for replenishing the negative pressure is not performed, and the brake is applied as described in the aforementioned Corona Premio manual. Switching to the ideal air-fuel ratio at the time of braking does not cause deterioration of fuel efficiency, so that it can contribute to improvement of fuel efficiency.

According to a second aspect of the present invention, in the first aspect, there is provided a brake operation detecting means capable of storing an ON / OFF state of the brake operation within a predetermined time in the past, and the control map of the controller is When the absolute value of the output of the negative pressure sensor falls below the second threshold value, the absolute value of the negative pressure in the intake pipe increases in accordance with the decrease in the absolute value of the output value of the negative pressure sensor. A first mode for
A second mode in which the absolute value of the negative pressure is further increased by a predetermined amount than the first mode, wherein the controller controls the control mechanism unit also according to a detection result of the brake detection unit, If the detection result of the brake operation detecting means indicates that the current brake operation is OFF and the brake operation has changed from ON to OFF within a predetermined time in the past, the first mode is selected and the current mode is selected. The brake operation is ON or the current brake operation is O
The engine negative pressure control device is characterized in that the second mode is selected when the brake operation is FF and the brake operation is always OFF during a predetermined time in the past.

[0014] In the above configuration,
A brake operation detecting means capable of storing the ON / OFF state of the brake operation within a predetermined time in the past is added. According to the detection result from the brake operation detecting means, the control map shown in FIG. The region below the second threshold value PH 'is improved.

FIG. 6 shows an improved control map. The negative pressure sensor used in this case is limited to a linear sensor type. In the control map shown in FIG. 6, in a region where the negative pressure value is equal to or less than PH ′, a first mode in which the absolute value of the negative pressure in the intake pipe is increased according to the decrease in the absolute value of the output value of the negative pressure sensor; A second mode in which the absolute value of the negative pressure is further increased by a predetermined amount than in the first mode. If the detection result of the brake operation detecting means indicates that the current brake operation is OFF and the brake operation has changed from ON to OFF within a predetermined time in the past, the first mode is selected, Brake operation is ON
Or the current brake operation is OFF and the brake operation is always OFF within a predetermined time in the past.
If so, the second mode is selected. When the first mode is selected, the brake is not currently applied, and the brake has been applied within a predetermined time in the past. Therefore, even if the negative pressure value has dropped to PH 'or less, Is not operated, and negative pressure is being replenished for the next brake operation. On the other hand, when the second mode is selected, the negative pressure value is P because the brake is currently applied, or the brake is not currently applied but the brake has not been applied since a predetermined time in the past.
If the pressure drops below H ', it is necessary to replenish the negative pressure immediately. Therefore, when the negative pressure value is lower than PH ′, the necessity of replenishing the negative pressure is larger in the second mode selection than in the first mode selection. Therefore, as shown in FIG. Therefore, the difference was decided.

The brake operation detecting means determines whether the brake operation is ON or OFF by turning on a brake lamp switch.
・ It is desirable to detect by OFF.

According to a third aspect of the present invention, in the second aspect, a vehicle speed sensor for detecting a vehicle speed is provided, wherein the controller controls the control mechanism in accordance with an output of the vehicle speed sensor, and The detection result of the operation detecting means is ON / OF of the brake operation more than a predetermined number of times within a predetermined time in the past.
The engine negative pressure control device is characterized in that the second mode is always selected when there is an F change and the output of the vehicle speed sensor is equal to or greater than a predetermined value.

This is achieved by the configuration according to claim 2,
A vehicle speed sensor for detecting the vehicle speed is added, and the detection result from the brake operation detecting means has changed ON / OFF of the brake operation more than a predetermined number of times within a predetermined time in the past,
When the vehicle speed is equal to or higher than a predetermined value, it is determined that the vehicle is traveling on a descending plate. When the absolute value of the negative pressure is equal to or lower than a second threshold value PH ′, control is performed such that the second mode is always selected. It is.

When it is determined that the vehicle is descending, a reliable braking force is required. Therefore, when the negative pressure is insufficient (the absolute value of the negative pressure is equal to or less than PH '), the mode in which the negative pressure is replenished is the fastest. Should be selected, and the second mode in which the negative pressure replenishment is fast is always selected irrespective of the determination of the first and second modes.

As described above, the brake operation is turned on.
・ Since the negative pressure in the intake pipe decreases each time the valve is turned off, this characteristic is used to add counter means for the number of negative pressure reductions. When the vehicle speed is equal to or higher than a predetermined value within the time and the vehicle speed is equal to or higher than a predetermined value, it may be determined that the vehicle is descending, and control may be performed so as to select the second mode.

According to a fourth aspect of the present invention, in the second or third aspect, there is provided a pedaling force sensor or a brake pedal stroke sensor for detecting a pedaling force of a brake pedal, and the controller is provided with the pedaling force sensor or the brake pedal stroke sensor. Controlling the control mechanism also according to the output, if the output value of the pedaling force sensor is greater than a predetermined value,
When the rate of change of the output of the pedaling force sensor is larger than a predetermined value, or when the brake pedal stroke sensor speed is larger than a predetermined value, the absolute value of the negative pressure in the intake pipe is enabled without following the control map. The engine negative pressure control device is characterized in that the control mechanism is controlled so as to be raised as much as possible.

In this case, a pedal force sensor or a stroke sensor for detecting a pedal force or a stroke of the brake pedal is added to the configuration according to the second or third aspect, and the output value of the pedal force sensor is larger than a predetermined value. If the rate of change of the output value is larger than a predetermined value, or if the brake pedal stroke sensor speed is larger than a predetermined value, it is determined that the emergency braking is performed, and the controller does not follow the control map, and the negative pressure in the intake pipe is determined. Is controlled so as to increase the absolute value of.

By performing such control, when it is determined that an emergency brake has been applied, the negative pressure in the intake pipe can be increased as much as possible, and the reduced negative pressure can be instantaneously replenished as much as possible. A braking force can be secured.

[0024]

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

FIG. 1 is a conceptual diagram of an engine negative pressure control device according to one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an intake pipe 5 of the engine.
A vacuum booster that introduces more negative pressure to assist the braking force of the vehicle, and 2 is a negative pressure sensor that detects a negative pressure in the vacuum booster 1 (in the intake pipe of the engine). An intake pipe 5 of the engine is connected to the vacuum booster 1, and a negative pressure is supplied from the intake pipe 5 of the engine. A check valve 6 is provided at a connection portion between the vacuum booster 1 and the intake pipe 5 of the engine to prevent backflow of air and prevent air from entering the vacuum booster 1 from the intake pipe 5 of the engine. are doing. Thereby, even when the pressure in the intake pipe 5 of the engine becomes positive pressure or the like when the engine is stopped, the required negative pressure can be maintained in the vacuum booster 1 and stable braking performance can be maintained. Plays a function.

Reference numeral 3 denotes a controller, which is a negative pressure sensor 2
Signal (not shown), the ON / OFF state of the brake operation within a predetermined time in the past (ON of the brake lamp switch)
(OFF state) based on the detection result from the brake operation detecting means capable of storing the signal, a signal from a vehicle speed sensor (not shown), a signal from a pedaling force sensor (not shown) for detecting the pedaling force of the brake pedal, and the like. The control unit 4 controls the absolute value of the negative pressure. This control is basically performed as shown in FIG.
With the exception of the control map shown in
If the condition described in claim 3 is satisfied, it is determined that the vehicle is going down, and the second mode in FIG. 6 is selected. If the condition described in claim 4 is satisfied, an emergency It is determined that braking is performed, and control is performed so as to increase the absolute value of the negative pressure in the intake pipe 5 as much as possible without following the control map of FIG.

In order to increase the absolute value of the negative pressure, for example, control may be performed such that the electronic throttle valve constituting the control mechanism 4 is closed by a predetermined amount.

In the vehicle having the above-described engine negative pressure control device according to the present invention, the operation and effect of the present negative pressure control device in various braking states as shown in FIGS. explain.

FIG. 2 shows the transition of the pedaling force, the negative pressure, and the braking force with respect to time in a single loose braking state. In FIG. 2, the thick solid line indicates the pedal effort, the thin solid line indicates the negative pressure, and the dotted line indicates the braking force.

In FIG. 2, it is assumed that both the pedal depression force Fa and the temporal change dFa / dt of the pedal depression force do not exceed a predetermined value. The negative pressure value PH
Is equivalent to the negative pressure value PH in FIG. 6, and the negative pressure value PL is
This is a negative pressure value when the air-fuel ratio of the air-fuel mixture sucked by the intake pipe 5 is switched from the ideal air-fuel ratio to the lean air-fuel ratio. That is, when the negative pressure value is equal to or less than PL, the controller 3 controls the supply air amount according to the control map shown in FIG. 6 under the ideal air-fuel ratio control accompanied by some deterioration of the fuel efficiency in order to recover the negative pressure. When the negative pressure value is equal to or higher than PL, the negative pressure has been sufficiently recovered, and the lean air-fuel ratio control is performed to improve fuel efficiency.

When the brake pedal is operated and the pedal depression force increases, the negative pressure starts to decrease under the influence of the operation of the diaphragm in the vacuum booster, and the pedal depression force reaches the maximum value F.
When the pressure reaches a, the negative pressure falls below PH. The controller 3 starts controlling the supply air amount according to the control map of FIG. 6, the supply air amount becomes K1, and the negative pressure replenishment is started. As a result, the negative pressure began to recover and exceeded the PH again,
The supply air amount is returned to K0 in FIG.
Meanwhile, the negative pressure has increased to PL. Here, the air-fuel ratio control of the air-fuel mixture is switched to the lean air-fuel ratio control. Some time after the negative pressure reaches PL, the brake pedal is released, and the pedal depression force disappears.

Under the above circumstances, it can be seen that the time during which the negative pressure falls below the PH is very short, and the braking force is sufficiently secured in accordance with the pedal depression force during the pedal operation. In addition, even when the pedal effort is constant Fa, the braking force increases in response to the increase in the negative pressure. Further, in such a single loose braking state, the mode is switched to the lean air-fuel ratio control even during braking, so that deterioration in fuel efficiency can be suppressed.

FIG. 3 shows the transition of the pedal effort, the negative pressure, and the braking force over time in a single-shot, strong emergency braking state mainly used for danger avoidance. FIG.
In the graph, the thick solid line indicates the pedal effort, the thin solid line indicates the negative pressure, and the dotted line indicates the braking force. Further, the dashed line indicates the negative pressure and the braking force when the supply air amount is controlled in accordance with the control map of FIG.

In FIG. 3, it is assumed that at least one of the pedal effort Fb and the temporal change dFb / dt of the effort exceeds a predetermined value. The negative pressure values PH and PL are the same as those in FIG.

When the brake pedal is suddenly operated and the pedal depression force increases, the negative pressure starts to decrease rapidly due to the operation of the diaphragm in the vacuum booster, and the negative pressure is reduced before the pedal depression force reaches the maximum value Fb. Is below PH.
Here, since the controller 3 satisfies the condition of claim 4, it determines that it is an emergency brake and starts the control for increasing the absolute value of the negative pressure in the intake pipe 5 as much as possible without following the control map of FIG. I do. As a result, the negative pressure is quickly replenished, and as a result, the negative pressure is restored to PL in a short time.
Some time after the negative pressure reaches PL, the brake pedal is released, and the pedal depression force disappears.

Under the above situation, even when the pedaling force is constant at Fb, the braking force sharply increases in response to the rapid rise of the negative pressure, and a sufficient braking force is secured. As a comparison, when the controller 3 performs control in accordance with the control map of FIG. 6, the recovery of the negative pressure is delayed, the braking force reaches a plateau, and it can be seen that a sufficient braking force cannot be secured. Also, in such an emergency braking state, the supply air amount is rapidly reduced, so that the engine torque may fluctuate.However, a slight torque fluctuation is allowed, priority is given to safety, and stable braking force is applied. The main focus is on securing.

FIG. 4 shows the pedal depression force, the negative pressure, and the braking force when the braking force is insufficient and the braking force is gradually increased in the short-time intermittent brake depression pattern observed when the vehicle descends on a winding road. The transition of the power with respect to time is shown. In FIG. 4, the thick solid line indicates the pedal effort, the thin solid line indicates the negative pressure, and the dotted line indicates the braking force. In addition, the dashed line shows the graph of FIG. 6 even when the negative pressure is PH ′ or less for comparison.
5 shows the negative pressure and the braking force when the supply air amount is controlled to a constant value K1 without following the control map of FIG.

In FIG. 4, the condition of the pedal operation pattern and the output of the vehicle speed sensor may or may not satisfy the condition of the descending traveling of claim 3. The negative pressure values PH and PL are the same as those in FIG.
H 'is the same as PH' in FIG.

By the first brake operation, the negative pressure becomes PH.
The absolute value of the negative pressure is lower than PH ′ at point a by the second brake operation. At point a, the brake operation is in the ON state.
The second mode in FIG. 6 is selected, the rapid replenishment of the negative pressure is started, and at the start of the third brake operation, the absolute value of the negative pressure has recovered to PH 'or more. When the third brake operation is performed in this state, the absolute value of the negative pressure becomes P again.
However, as in the second brake operation, the controller 3 selects the second mode in FIG. 6 and starts rapid replenishment of the negative pressure again, and the negative pressure reaches PL in a short time. ing.

Under the above circumstances, the absolute value of the negative pressure is PH '
The period during which it falls below is slight, and the braking force is 3
It can be seen that it is sufficiently secured even at the time of the second brake operation. As a comparison, when the controller 3 performs the control of the related art in which the supply air amount is constant at K1 without following the control map when the absolute value of the negative pressure is equal to or less than PH ′,
The recovery of the negative pressure was delayed, and the absolute value of the negative pressure did not recover to PH 'at the start of the third brake operation, and the auxiliary force of the vacuum booster did not work in the early stage of the third brake operation, and the braking force was also low. It can be seen that the plateau has reached a plateau and a sufficient braking force cannot be secured.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, but includes various embodiments according to the principle of the present invention.

[0043]

As described above, according to the present invention,
It is possible to provide a negative pressure control device for an engine that can generate a sufficient braking force under any conditions while minimizing deterioration of fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an engine negative pressure control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operation and an effect of the present negative pressure control device in a single-shot loose braking state in one embodiment of the present invention.

FIG. 3 is a diagram showing an operation and an effect of the present negative pressure control device in a single-shot and strong emergency braking state in one embodiment of the present invention.

FIG. 4 is a diagram showing an operation and an effect of the present negative pressure control device in a case where the braking force is insufficient and the pedal is gradually increased in the pattern of stepping on the intermittent brake in a short time in one embodiment of the present invention. .

FIG. 5 is a control map of the controller according to claim 1 in one embodiment of the present invention.

FIG. 6 is a control map of the controller according to claim 2 in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum booster 2 Negative pressure sensor 3 Controller 4 Control mechanism part 5 Intake pipe (engine intake system)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 3D041 AA21 AA33 AA65 AA66 AA71 AB01 AC27 AD05 AD41 AD51 AE04 AE41 AF00 AF01 3D049 BB05 HH08 HH42 HH47 HH48 HH51 KK07 QQ04 RR04 3G093 AA01 EC07 DB05 CB04 FA07 FA10 FB01 FB05 3G301 HA04 HA15 JA02 JA03 KA16 LA03 LC03 NC02 ND02 NE01 NE18 PA07A PA07Z PA11A PA11Z PF01Z PF05A PF05Z

Claims (4)

[Claims] 1. A vacuum booster for introducing a negative pressure from an intake pipe of an engine to assist a braking force of a vehicle, a negative pressure sensor for detecting a negative pressure in the vacuum booster, and controlling a negative pressure in the intake pipe. And a controller that controls the control mechanism in accordance with at least the output of the negative pressure sensor, wherein the controller sets the absolute value of the output value of the negative pressure sensor to a first threshold value. If the absolute value of the negative pressure in the intake pipe increases by a predetermined amount, the absolute value of the output value of the negative pressure sensor becomes equal to or less than a second threshold smaller than the first threshold. An engine negative pressure control device according to claim 1, wherein the control mechanism is controlled according to a control map that further increases the absolute value of the negative pressure in the intake pipe when the pressure is decreasing. 2. The control system according to claim 1, further comprising a brake operation detecting means capable of storing an ON / OFF state of the brake operation within a predetermined time in the past, wherein the control map of the controller includes an absolute value of an output of the negative pressure sensor. A first mode for increasing the absolute value of the negative pressure in the intake pipe in accordance with a decrease in the absolute value of the output value of the negative pressure sensor, when the value has decreased below the second threshold value; A second mode in which the absolute value of the negative pressure is further increased by a predetermined amount than the first mode, wherein the controller controls the control mechanism section also in accordance with a detection result of the brake detection means, If the result of the brake operation detecting means indicates that the current brake operation is OFF and the brake operation has changed from ON to OFF within a predetermined time in the past, the first mode is selected, and the current brake operation is selected. The second mode is selected when the rake operation is ON or the current brake operation is OFF and the brake operation is always OFF within a predetermined time in the past. Negative pressure control device. 3. The vehicle according to claim 2, further comprising a vehicle speed sensor for detecting a vehicle speed, wherein the controller controls the control mechanism in accordance with an output of the vehicle speed sensor, and a detection result of the brake operation detecting means is provided. When the ON / OFF of the brake operation has changed more than a predetermined number of times within a predetermined time in the past and the output of the vehicle speed sensor is equal to or more than a predetermined value, the second time is always used.
An engine negative pressure control device characterized by selecting a mode. 4. The control device according to claim 2, further comprising a pedaling force sensor or a brake pedal stroke sensor for detecting a pedaling force of a brake pedal, wherein the controller also controls the controller in response to an output of the pedaling force sensor or the brake pedal stroke sensor. Controlling the mechanism, if the output value of the pedal force sensor is larger than a predetermined value, if the rate of change of the output of the pedal force sensor is larger than a predetermined value, or if the brake pedal stroke sensor speed is larger than a predetermined value,
An engine negative pressure control device according to claim 1, wherein the control mechanism is controlled so as to increase an absolute value of the negative pressure in the intake pipe as much as possible without following the control map.