JP2004204724A - Automatic engine stopping and starting device for vehicle - Google Patents

Automatic engine stopping and starting device for vehicle Download PDF

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Publication number
JP2004204724A
JP2004204724A JP2002372312A JP2002372312A JP2004204724A JP 2004204724 A JP2004204724 A JP 2004204724A JP 2002372312 A JP2002372312 A JP 2002372312A JP 2002372312 A JP2002372312 A JP 2002372312A JP 2004204724 A JP2004204724 A JP 2004204724A
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JP
Japan
Prior art keywords
engine
vehicle
brake booster
brake
negative pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2002372312A
Other languages
Japanese (ja)
Inventor
Naoki Imamura
Michiharu Okada
Hiroyuki Takebayashi
Hisami Terajima
Makoto Yuasa
直樹 今村
久視 寺島
道治 岡田
誠 湯浅
広行 竹林
Original Assignee
Mazda Motor Corp
マツダ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mazda Motor Corp, マツダ株式会社 filed Critical Mazda Motor Corp
Priority to JP2002372312A priority Critical patent/JP2004204724A/en
Publication of JP2004204724A publication Critical patent/JP2004204724A/en
Application status is Pending legal-status Critical

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02NSTARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
    • F02N11/00Starting of engines by means of electric motors
    • F02N11/08Circuits or control means specially adapted for starting of engines
    • F02N11/0814Circuits or control means specially adapted for starting of engines comprising means for controlling automatic idle-start-stop
    • F02N11/0818Conditions for starting or stopping the engine or for deactivating the idle-start-stop mode
    • F02N11/0833Vehicle conditions
    • F02N11/084State of vehicle accessories, e.g. air condition or power steering
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02NSTARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
    • F02N2200/00Parameters used for control of starting apparatus
    • F02N2200/08Parameters used for control of starting apparatus said parameters being related to the vehicle or its components
    • F02N2200/0807Brake booster state
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02NSTARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
    • F02N2200/00Parameters used for control of starting apparatus
    • F02N2200/12Parameters used for control of starting apparatus said parameters being related to the vehicle exterior
    • F02N2200/124Information about road conditions, e.g. road inclination or surface
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/40Engine management systems
    • Y02T10/48Switching off the internal combustion engine, e.g. stop and go

Abstract

<P>PROBLEM TO BE SOLVED: To fully secure functions of a brake booster and fully achieve an aim of idle stop by varying a reference pressure in the brake booster used for determining whether idle stop should be forcibly released or not in accordance with the road gradient. <P>SOLUTION: In an idle stop vehicle 1, an engine 10 is automatically stopped when an engine stop condition is established at stop of the vehicle, and the engine 10 is automatically started when the engine start condition is established after that. The brake booster 72 with the usage of an intake negative pressure of the engine 10 is provided between a brake pedal 71 and a master cylinder 73, and the engine 10 is forcibly started when the negative pressure introduced into the brake booster 72 at automatic stop of the engine 10 exceeds a predetermined reference pressure. The reference pressure is lowered when the road gradient is steep compared to the one when the load gradient is gentle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of so-called engine idle stop in which the engine is automatically stopped and started when the vehicle is stopped, and in particular, the driver utilizes the engine suction negative pressure by automatically stopping the engine. When the negative pressure in the brake booster which assists the braking operation of the engine becomes high, the engine belongs to the technical field of forcibly starting the engine to generate the suction negative pressure of the engine.
[0002]
[Prior art]
In general, in order to improve fuel efficiency, reduce the emission of environmental pollutants or carbon dioxide, and suppress noise, a predetermined engine stop condition (for example, when a brake pedal is depressed, accelerator When the pedal is not depressed, etc., the engine is automatically stopped, and then the predetermined engine start conditions (for example, the brake pedal is not depressed or the accelerator pedal is depressed) Etc.), a so-called idle stop vehicle that automatically starts the engine when the condition is satisfied is known.
[0003]
In addition, a brake booster (a booster) using an intake negative pressure of an engine may be provided between a brake pedal and a master cylinder to assist a driver's braking operation. However, if the idle stop is applied as described above when the vehicle is stopped, the engine automatically stops, and accordingly, the suction negative pressure of the engine does not occur, and as a result, the negative pressure in the brake booster becomes atmospheric pressure. It gradually increases (the degree of negative pressure decreases), and the burden of the driver's braking operation (e.g., depression force on the brake pedal) while the vehicle is stopped increases.
[0004]
Therefore, conventionally, a sensor for detecting the value of the negative pressure (brake booster negative pressure) introduced into the brake booster is provided, and the brake booster negative pressure detected by the sensor detects a predetermined reference pressure during automatic stop of the engine. It has been proposed to stop the idle stop and forcibly start the engine when the engine start condition is not satisfied even when the engine start condition is not satisfied (see Patent Document 1). Then, the negative suction pressure of the engine is generated again, and the assist of the braking operation by the brake booster is sufficiently ensured.
[0005]
[Patent Document 1]
JP 2001-12272 A (page 2 etc.)
[0006]
[Problems to be solved by the invention]
However, in the above prior art, the reference pressure of the brake booster negative pressure used for determining whether to forcibly start the engine (forcibly canceling the idle stop) is changed according to the atmospheric pressure, but is changed according to the road surface gradient. Does not change, the following problems occur. That is, the road surface gradient when the vehicle stops and the engine stops automatically varies depending on the situation. As a result, for example, when there is a road surface gradient such as an uphill or a downhill, the road surface gradient such as a flat road is used. The driver tends to demand a larger braking force by depressing the brake pedal more strongly as compared with a place without the brake pedal. Actually, when the vehicle stops at a place where the road surface is steep (a steep slope regardless of uphill or downhill) and the engine stops automatically, the place where the road surface is gentle slope (uphill or downhill) If the vehicle stops at a place where the gradient is gentle regardless of the slope and the braking force is not increased as compared with when the engine is automatically stopped, the vehicle moves unexpectedly due to the road surface gradient (retreat when climbing uphill, (If it is downhill, it may move forward).
[0007]
However, if the reference pressure of the brake booster negative pressure used for determining whether or not to start the engine forcibly is uniform regardless of the road surface gradient as in the above-described prior art, the reference pressure is high when the road surface gradient is steep. Is too high (the degree of negative pressure is too small), the timing of the forced start of the engine tends to be delayed. As a result, the recovery of the assistance of the braking operation by the brake booster tends to be delayed, the braking force tends to be insufficient, and the above-described problem that the vehicle unexpectedly moves due to the road gradient is inevitable. On the other hand, when the road gradient is gentle, the reference pressure is too low, and the timing of the forced start of the engine is slightly advanced. As a result, the original purpose of the idle stop, such as improving fuel efficiency, reducing emissions, and suppressing noise, is impaired.
[0008]
In view of the above, the present invention provides a brake booster in which the reference pressure of the brake booster negative pressure used for determining whether to forcibly cancel the idle stop is changed in accordance with the road surface gradient in the idle stop vehicle. The main task is to achieve a good balance between ensuring security and achieving the purpose of idling stop.
[0009]
[Means for Solving the Problems]
That is, according to the invention described in claim 1 of the present application, a brake booster utilizing an intake negative pressure of an engine is provided between a brake pedal and a master cylinder, and a brake booster detecting a negative pressure introduced into the brake booster is provided. A negative pressure detecting means for automatically stopping the engine when a predetermined engine stop condition is satisfied when the vehicle is stopped, and then automatically starting the engine when a predetermined engine start condition is satisfied; A vehicle having a starting means and an engine forced starting means for forcibly starting the engine when the brake booster negative pressure detected by the detecting means during the automatic stop of the engine becomes higher than a predetermined reference pressure. An automatic stop / start device for an engine, comprising: a road gradient related value detecting means for detecting a value related to a road gradient; When the surface is detected to be steep, as compared to when it is detected that is low-gradient, characterized in that the reference pressure changing means to reduce the predetermined reference pressure is provided.
[0010]
According to the present invention, in the idle stop vehicle, the reference pressure of the brake booster negative pressure used for determining whether or not to forcibly cancel the idle stop is changed according to the road surface gradient. Securement and sufficient achievement of the purpose of idle stop are compatible. More specifically, when the road surface gradient is steep, the reference pressure is set lower than when the road surface gradient is gentle, so that the timing of releasing the idle stop is advanced. As a result, the degree of the negative pressure of the brake booster does not become excessively small, the recovery of the assist of the braking operation by the brake booster is accelerated, the function of the brake booster is fully secured, and the vehicle is mounted on a steep road surface gradient. Is prevented from moving unexpectedly due to the road surface gradient. On the other hand, when the road surface gradient is gentle, the timing of releasing the idle stop is delayed because the reference pressure is increased as compared with when the road gradient is steep. As a result, the purpose of idling stop is sufficiently achieved, and fuel economy improvement, emission reduction, noise suppression, and the like can be satisfactorily realized even on a gentle road surface gradient.
[0011]
Next, according to a second aspect of the present invention, in the first aspect of the present invention, there is provided a loading weight-related value detecting means for detecting a value related to the loading weight of the vehicle, and the reference pressure changing means comprises When the detecting means detects that the loaded weight is large, the predetermined reference pressure is lower than when it is detected that the loaded weight is small.
[0012]
According to the present invention, in the idle stop vehicle, the reference pressure of the brake booster negative pressure used to determine whether to forcibly cancel the idle stop is changed in accordance with the loaded weight in addition to the road surface gradient. The following effects are added. That is, when there are many loads and occupants and the load weight is large, the driver tends to depress the brake pedal more strongly and request a larger braking force than when the load is not large. In fact, when the vehicle is stopped on a road gradient (regardless of uphill or downhill) and the engine stops automatically, the braking force is higher when the load is large than when the load is small. If not increased, the possibility that the vehicle unexpectedly moves (retreats on an uphill and moves forward on a downhill) due to the road surface gradient increases.
[0013]
Therefore, according to the present invention, by changing the reference pressure of the brake booster negative pressure used to determine whether to forcibly cancel the idle stop according to the loaded weight, it is possible to ensure the function of the brake booster sufficiently, This is to ensure that the objective of the idle stop is sufficiently achieved. More specifically, when the loaded weight is large, the reference pressure is made lower than when the loaded weight is small, so that the timing of releasing the idle stop is advanced. As a result, the recovery of the assistance of the braking operation by the brake booster is hastened, the function of the brake booster is fully secured, and the problem that the vehicle unexpectedly moves due to the road gradient when the loaded weight is large is avoided. . On the other hand, when the load weight is small, the reference pressure is increased as compared with when the load weight is large, so that the timing of releasing the idle stop is delayed. As a result, the purpose of the idle stop is sufficiently achieved, and when the load weight is small, improvement in fuel efficiency, reduction in emission, suppression of noise, and the like are favorably realized.
[0014]
Next, according to a third aspect of the present invention, in the first or second aspect of the invention, the braking force holding means for holding a braking force for preventing movement of the vehicle when the vehicle is stopped, and the braking force holding means for holding the vehicle when the vehicle starts moving. And a braking force reducing means for reducing the braking force.
[0015]
According to the present invention, when the vehicle is stopped, the braking force for preventing the movement of the vehicle is held. Therefore, when the vehicle is stopped and an idle stop is applied, the driver's brake pedal can be released without applying the side brake. Even if the depression of the vehicle suddenly weakens, it is possible to avoid such a problem that the vehicle unexpectedly moves (retreats on an uphill and moves forward on a downhill) due to the road surface gradient. Further, when the vehicle starts, the held braking force is reduced, so that the vehicle can be started smoothly and well without a brake drag feeling. Hereinafter, the present invention will be described in more detail through embodiments.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIG. 1, a vehicle 1 according to the present embodiment is an FF (Front Engine / Front Drive) vehicle, in which an engine 10 is disposed horizontally in an engine room at a front part of a vehicle body. A transmission 30 is connected to the transmission 10 via a torque converter 20. The output of the transmission 30 is transmitted to the left and right front wheels 61 and 62 via the differential 40. The vehicle 1 is a so-called idle-stop vehicle for improving fuel efficiency, reducing emissions of environmental pollutants or carbon dioxide, suppressing noise, and the like, and includes a starter motor 50 for starting the engine 10.
[0017]
The brake system of the vehicle 1 employs a well-known disc brake in this embodiment. That is, the driver's depressing force of the brake pedal 71 is assisted by a brake booster (power booster) 72 using a negative pressure (suction negative pressure) in the intake pipe of the engine 10 and transmitted to the master cylinder 73, and the pedaling force is applied. The brake fluid pressure is generated according to. The brake fluid pressure is transmitted to the wheel cylinders built in the calipers 76 to 76 of the wheels 61 to 64 through the brake fluid pressure passages 74 and 75, and the discs 77 to 77 which rotate integrally with the wheels 61 to 64 are transmitted to the brake cylinders. The pad is pinched and a braking force is generated. Of course, not only disc brakes, but also drum brakes, in which a shoe is pressed against a drum that rotates together with each wheel to generate a braking force, and a braking force that tightens a drum that rotates together with each wheel with a band A band-type brake or the like in which the wobble occurs may be adopted.
[0018]
The master cylinder 73 is a tandem type having two discharge ports, and the brake hydraulic pressure passages 74 and 75 are of a cross type (X piping type) in the present embodiment. That is, the hydraulic passages 74 and 75 extending from the respective discharge ports of the master cylinder 73 are each branched into two in the middle, and one of the passages (the first passage) 74 is provided with the caliper 76 of the left front drive wheel 61 and the right rear. The other passage (second passage) 75 reaches the caliper 76 of the driven wheel 64 and reaches the caliper 76 of the right front driving wheel 62 and the caliper 76 of the left rear driven wheel 63. Of course, the present invention is not limited to the cross system, but may be a front-rear split system in which one passage extends to left and right front wheels and the other passage extends to left and right rear wheels.
[0019]
Solenoid valves 80, 90 are provided in each of the brake fluid pressure passages 74, 75. As clearly shown in FIGS. 2 and 3 by taking the first solenoid valve 80 as an example, the solenoid valve 80 is a normally open on / off solenoid valve using a DC solenoid. When no current is flowing through the coil 81, the plunger 82 is urged by the spring 83 and retracts from the hydraulic passage 74 as shown in FIG. 2. Thus, the hydraulic pressure passage (upstream passage) 74a on the master cylinder 73 side and the hydraulic pressure passage (downstream passage) 74b on the caliper 76 side (wheel cylinder side) which sandwich the solenoid valve 80 are completely connected. Then, the hydraulic passage 74 is fully opened. On the other hand, when an electric current is applied to the coil 81, the plunger 82 advances into the hydraulic passage 74 while contracting the spring 83, as shown in FIG. Thus, the upstream passage 74a and the downstream passage 74b are completely shut off, and the hydraulic passage 74 is fully closed.
[0020]
However, the duty of the current flowing through the DC solenoid is controlled by a PWM (pulse width modulation) method, so that the solenoid valve 80 can be used like a proportional control valve. By changing the duty value (the ratio of the ON time per one ON / OFF cycle) in the duty control, the degree of communication between the upstream passage 74a and the downstream passage 74b is changed, and the brake fluid pressure (braking force) of the downstream passage 74b is changed. ) Can be controlled. The duty value when the solenoid valve 80 is off is 0%, and the duty value when it is on is 100%.
[0021]
As shown in FIG. 2, normally, the solenoid valve 80 is off and the hydraulic passage 74 is fully open. When the brake pedal 71 is depressed, the operating rod 71a of the pedal 70 pushes the valved rod 72a of the brake booster 72, the valved rod 72a pushes the push rod 72b, and the push rod 72b is pushed by the piston 73a of the master cylinder 73. push. The inside of the brake booster 72 is partitioned by a diaphragm 72c into two chambers 72d and 72e. The diaphragm 72c is connected to the push rod 72b.
[0022]
In the state of FIG. 2 in which the brake pedal 71 is not depressed, suction negative pressure (brake booster negative pressure) is acting on both the first chamber 72d and the second chamber 72e. However, in the state of FIG. 3 in which the brake pedal 71 is depressed, the action of the negative pressure on the first chamber 72d is stopped, and the atmospheric pressure is introduced into the first chamber 72d with the movement of the valved plunger 72a. . As a result, the driver's depression force on the brake pedal 71 is assisted from the first chamber 72d side to the second chamber 72e side. At this time, the piston 73a of the master cylinder 73 compresses the spring 73e provided between the piston 73a and the piston for the second passage 75 (not shown).
[0023]
In the master cylinder 73, the brake fluid pressure in the pressurizing chamber 73d increases from the moment the piston 73a crosses the relief port 73c of the reservoir 73b. Then, the pressurized brake fluid pressure is discharged to the fluid pressure passage 74 and reaches the wheel cylinder via the solenoid valve 80 (see the arrow in FIG. 2). When the electromagnetic valve 80 is turned on and the hydraulic pressure passage 74 is fully closed in this state, the pressurized brake hydraulic pressure remains in the downstream side passage 74b. In this state, even if the brake pedal 71 is released, the braking force of the downstream passage 74b does not decrease (see the arrow in FIG. 3).
[0024]
For example, while the piston 73a returns to the position of the relief port 73c of the reservoir 73b, a negative pressure is transiently generated in the upstream passage 74a, and the piston 73a returns relatively slowly. As a result, the brake fluid pressure in the upstream passage 74a decreases slowly. However, after the piston 73a returns to the position of the relief port 73c, the upstream passage 74a communicates with the reservoir 73b, and the piston 73a returns promptly. As a result, the brake fluid pressure in the upstream passage 74a quickly decreases to the atmospheric pressure (residual pressure). In any case, while the brake fluid pressure in the upstream passage 74a decreases as described above, the brake fluid pressure in the downstream passage 74b is blocked by the plunger 82 and the check valve 84 and decreases together. Nothing.
[0025]
When the brake pedal 71 is further depressed after the electromagnetic valve 80 is turned on and the hydraulic pressure passage 74 is fully closed, the depressed amount is increased via the check valve 84 to the downstream passage 74b. And the brake fluid pressure in the downstream passage 74b is increased.
[0026]
The above is the basic operation of the brake system in which the solenoid valves 80 and 90 are provided in the brake fluid pressure passages 74 and 75 connecting the master cylinder 73 and the wheel cylinder. Here, the first hydraulic passage 74 and the first solenoid valve 80 have been described as examples, but the same applies to the second hydraulic passage 75 and the second solenoid valve 90.
[0027]
As shown in FIG. 4, the vehicle 1 includes a control unit 100 for idling stop which controls fuel injection valves 11... 11, spark plugs 12. A hill-hold control unit 200 for controlling the hill 90 is mounted. An idle stop control unit (ISECU) 100 detects a signal of a brake switch 110 that is turned on when a brake pedal is depressed, a signal of a throttle opening sensor 120 that detects an opening of a throttle valve of the engine 10, and a vehicle speed. A signal of a vehicle speed sensor 130, a signal of a range switch 140 for detecting a selected range, a signal of a water temperature sensor 150 for detecting a temperature of cooling water of the engine 10, and a signal interposed between the brake pedal 71 and the master cylinder 73. In addition to inputting a signal of a booster negative pressure sensor 160 for detecting a brake booster negative pressure introduced into the brake booster 72, a signal of an engine rotation sensor 170 for detecting the number of revolutions of the engine 10, etc., a load / occupant input key 180 Weight of the vehicle 1 such as cargo and occupants input via the Signal associated values, and inputs the signal of the inclination angle sensor 210 for detecting a road surface gradient. The hill hold control unit (HHECU) 200 receives a signal from the engine rotation sensor 170, a signal from the inclination angle sensor 210, a signal from a brake fluid pressure sensor 220 that detects brake fluid pressure in the downstream passages 74b and 75b, and the like. In addition, an idle stop flag signal is input from the ISECU 100.
[0028]
Here, the cargo / occupant input key 180 is provided, for example, in a driver's seat. The driver uses this input key 180 to input the number of occupants (for example, one person: 60 kg if there is no passenger) and, if there is a load, the weight of the load. If possible, the vehicle 1 may be provided with a weight detection device, and the ISECU 100 may automatically measure the total loaded weight of the vehicle 1 such as a load or an occupant.
[0029]
FIG. 5 is a flowchart illustrating an example of a specific operation of the idle stop control performed by the ISECU 100. First, after initialization is performed in step S11, various determinations are performed in steps S12 to S17. When all determinations are YES (that is, when a predetermined engine stop condition is satisfied when the vehicle stops), step S18 is performed. To stop the fuel injection, and stop the spark ignition in step S19 to automatically stop the engine 10. Then, in step S20, an idle stop flag is set to 1 to indicate that the engine 10 is automatically stopped, and then the process returns to step S12.
[0030]
In this example, the brake switch 110 is on (step S12), the throttle valve is fully closed (step S13), the vehicle speed is zero (step S14), and the selected range is the D range or N range. The range (step S15), the condition that the brake booster negative pressure is lower than the predetermined reference pressure P (step S16), and the condition that other prohibition conditions are not satisfied (step S17) are the idle stop conditions. ing. Here, the other prohibition conditions in step S17 include, for example, that the engine water temperature is lower than a predetermined temperature, that the air conditioner or the like is operating and the electric load is large, and the like.
[0031]
In addition, the fact that the brake booster negative pressure is lower than the predetermined reference pressure P in step S16 is one of the idle stop conditions because the engine 10 is idle-stopped and the negative suction pressure of the engine 10 is not generated. As a result, the brake booster negative pressure gradually increases toward the atmospheric pressure (the degree of the brake booster negative pressure decreases), and when the brake booster negative pressure becomes higher than a predetermined reference pressure P, the brake is released. Since the assisting force of the booster 72 decreases and the burden of the driver on the braking operation (such as the pressing force of the brake pedal 71) increases, such a problem is prevented. That is, the determination in step S16 is a determination as to whether the engine 10 is forcibly started (idle stop is forcibly released). Further, the reference pressure P is a reference pressure of a brake booster negative pressure used for determining whether to forcibly start the engine 10 as described above.
[0032]
In this case, the reference pressure P is changed according to the road surface gradient as shown in FIG. As a result, a sufficient function of the brake booster 72 is ensured and a sufficient achievement of the purpose of the idle stop is achieved. More specifically, when the road surface gradient is steep (meaning that the gradient is steep irrespective of uphill or downhill), it is gentle (meaning that the gradient is gentle irrespective of uphill or downhill). The reference pressure P is set lower (the degree of the brake booster negative pressure is increased) as compared with the case. That is, the timing of releasing the idle stop is advanced, and as a result, the degree of the negative pressure of the brake booster does not become too small, and the recovery of the assist of the braking operation by the brake booster 72 is advanced, so that the function of the brake booster 72 is improved. It is possible to avoid such a problem that the vehicle 1 is completely secured and the braking force tends to be insufficient when the road surface gradient is steep, and the vehicle 1 unexpectedly moves due to the road surface gradient.
[0033]
On the other hand, when the road surface gradient is gentle, the reference pressure P is set higher (as a degree of the brake booster negative pressure) than when it is steep. That is, the timing of releasing the idle stop is delayed, and as a result, the purpose of the idle stop is sufficiently achieved, and the improvement of fuel consumption, emission reduction, noise suppression, and the like can be satisfactorily realized when the road surface gradient is gentle.
[0034]
The reference pressure P is also changed according to the load weight, as shown in FIG. As a result, the sufficient securing of the function of the brake booster 72 and the sufficient achievement of the purpose of the idle stop are both more reliably achieved. More specifically, when the load weight is large, the reference pressure P is set lower than when it is small. That is, the timing of releasing the idle stop is advanced, and as a result, the degree of the negative pressure of the brake booster does not become too small, and the recovery of the assist of the braking operation by the brake booster 72 is advanced, so that the function of the brake booster 72 is improved. When the vehicle 1 is fully secured and the load weight is large, the braking force tends to be insufficient, and a problem that the vehicle 1 unexpectedly moves due to the road surface gradient is avoided.
[0035]
On the other hand, when the load weight is small, the reference pressure P is set higher than when the load weight is large. That is, the timing of releasing the idle stop is delayed, and as a result, the purpose of the idle stop is sufficiently achieved, and when the load weight is small, the improvement of fuel consumption, emission reduction, noise suppression, and the like are favorably realized.
[0036]
Returning to FIG. 5, if at least one idle stop condition is not satisfied in steps S12 to S17, it is determined in step S21 whether the idle stop flag is 1 or not. ) Executes (restarts) fuel injection in step S22, executes (resumes) spark ignition in step S23, and turns on the starter motor 50 in step S24 to automatically start (automatically restart) the engine 10. Then, in step S25, after the idle stop flag is reset to 0 in order to indicate that the engine 10 is not automatically stopped, when the complete explosion of the engine 10 is confirmed in step S26 (for example, the engine speed increases to 500 rpm). ), The starter motor 50 is turned off in step S27, and the process returns to step S12. If NO in step S21 (idle stop is not being performed), the process returns to step S12.
[0037]
In response to such an operation of the ISECU 100, the HHECU 200 performs an operation (a hill hold control operation) exemplified in the flowchart in FIG. First, after initialization is performed in step S31, it is determined in step S32 whether or not the idle stop flag is 1. If YES (during idle stop), the hill hold control is performed in step S33. The valves 80 and 90 are fully closed (ON) (for that purpose, the duty value for the hill hold control valves 80 and 90 is set to 100%). And return. By completely closing the hill hold control valves 80 and 90 in this manner, the braking force (brake fluid pressure) requested by the driver when the vehicle 1 is stopped remains in the downstream passages 74b and 75b, and the vehicle 1 While the vehicle is stopped, a braking force (brake fluid pressure) for preventing the vehicle 1 from moving is maintained.
[0038]
On the other hand, if NO in step S32 (when the vehicle is not idling), it is determined in step S34 whether or not the road surface is uphill. If YES, the duty for the hill hold control valves 80 and 90 is determined in step S35. The attenuation value of the value is set to the attenuation value (X) for the upward slope. If NO in the above step S34 (if not uphill), it is determined in step S36 whether or not the road surface is downhill. If YES, the duty value for the hill hold control valves 80 and 90 is determined in step S37. The attenuation value is set to the attenuation value (Y) for the down slope. If NO in step S36 (when the slope is neither uphill nor downhill), the damping value of the duty value for the hill hold control valves 80 and 90 is set to the flat road damping value (Z) in step S38.
[0039]
Here, the uphill attenuation value (X) is the smallest among the three, the downhill attenuation value (Z) is the largest among the three, and the flat road attenuation value (Z) is a value between them. That is, when the road surface is uphill, the speed at which the braking force held during idle stop is reduced is minimized, and when the road surface is downhill, the speed at which the braking force held during idle stop is reduced is reduced. Make it the largest.
[0040]
In any case, in step S40, the duty value (100% initially) held while the vehicle 1 is stopped is gradually reduced by each of the attenuation values (X), (Y) or (Z). However, when the road surface is uphill, the process proceeds to step S33 until the complete explosion of the engine 10 is confirmed in step S39 (for example, until the engine speed increases to 500 rpm), and the duty value 100 % (Fully closed). Then, when the complete explosion of the engine 10 is confirmed (that is, at the timing when the creep force has increased to a level at which the vehicle can be moved after the automatic start of the engine), the process proceeds to step S40, and the duty value is reduced. Attenuate most slowly with minimum attenuation value (X). On the other hand, when the road surface is a downward slope or a flat road, the idle stop flag is reset to 0 immediately without waiting for the complete explosion of the engine 10 (that is, at the same timing as the automatic start of the engine). Proceeding to step S40, the duty value is attenuated most quickly at the maximum attenuation value (Y) (during a downward gradient). Alternatively, it is quickly attenuated at the intermediate attenuation value (Z) (for a flat road).
[0041]
Next, in step S41, it is determined whether or not the brake fluid pressure in the downstream passages 74b and 75b is equal to or less than a predetermined minute fluid pressure (for example, a fluid pressure slightly higher than the atmospheric pressure (residual pressure): 0.3 MPa in this example). Then, while the determination is NO, the process returns as it is. When the determination is YES, the hill hold control valves 80 and 90 are fully opened (off) in step S42 (for that, the hill hold control valve 80 is used). , 90 are set to 0% at a stroke). And return.
[0042]
The operation obtained by the above control operation will be described with reference to the time chart of FIG. Now, it is assumed that the driver depresses the brake pedal 71, the vehicle speed becomes zero at time t1, and the vehicle 1 stops. The idle stop condition is satisfied, idle stop is performed, and the idle stop flag is set to 1. Accordingly, the engine speed becomes zero from the idle speed Ni. Further, the duty value (Duty value) for the hill hold control valves 80 and 90 is set to 100% (ON: fully closed). As a result, a braking force that prevents the vehicle 1 from moving is maintained.
[0043]
In this state, after the vehicle 1 is stopped, even if the driver's depression of the brake pedal 71 weakens without knowing (brake operation amount solid line) without applying the side brake, the downstream passages 74b, 75b The brake fluid pressure does not decrease. Therefore, even if the vehicle 1 is stopped on an uphill, unexpected retreat is prevented, and even if the vehicle 1 is stopped on a downhill, unexpected forward movement is prevented. That is, in the idle stop vehicle, when the idle stop is applied to enhance the automatic startability of the engine 10, the power transmission path of the transmission 30 is cut off as in the P range and the N range. Unless the braking force is maintained in the passages 74b and 75b, the vehicle 1 may start to move inadvertently due to the road surface gradient.
[0044]
Of course, while the vehicle 1 is stopped and the engine 10 is idle stopped, as shown by the chain line, unless the brake operation amount decreases, the brake fluid pressure in the brake fluid pressure passages 74 and 75 does not decrease. However, the braking force requested by the driver when the vehicle 1 is stopped is held as it is, and the vehicle 1 is reliably moved not by the hill hold control valves 80 and 90 but by the continuous braking operation of the driver. Can be prevented.
[0045]
Then, when the driver starts depressing the brake pedal 71 and starts depressing the accelerator pedal, for example, when the engine start conditions are satisfied, the idle stop is released, and the idle stop flag is reset to 0. (Time t2). Accordingly, the engine speed starts to increase. In this case, especially when the road surface is uphill, the duty value is not changed until time t3 when the engine 10 completely explodes and the engine speed rises to the idle speed Ni (500 rpm) as illustrated by the solid line. Maintained at 100%, the brake fluid pressure is maintained at a value (braking force) that prevents the vehicle 1 from moving. This prevents the vehicle 1 from moving forward due to the creep force at time t3 when the engine speed has increased to the idle speed Ni.
[0046]
Then, as exemplified by reference character a, at time t3 when the engine 10 has completely exploded and the engine speed has increased to the idle speed Ni, the duty value is attenuated most slowly at the minimum attenuation value (X), The braking force is reduced most slowly. As a result, the vehicle 1 starts smoothly and smoothly without retreating. It should be noted that the vehicle speed in FIG. 8 illustrates a change when the road surface is uphill.
[0047]
On the other hand, when the road surface is downgraded, the duty value is attenuated most rapidly at the maximum attenuation value (Y) at the same time t2 as the automatic start of the engine 10, as exemplified by the broken line (a), and Power is reduced most quickly. As a result, the vehicle 1 starts smoothly and satisfactorily without the feeling of dragging the brake. Further, when the road surface is a flat road, the duty value is rapidly attenuated by the intermediate attenuation value (Z) at the same time t2 as the automatic start of the engine 10, as exemplified by the broken line (c), and Power is reduced quickly. As a result, the vehicle 1 starts smoothly and smoothly with a moderate acceleration feeling.
[0048]
Note that, when the road surface is downgraded, the duty value may be reduced to zero at once, not gradually, at the same time t2 as the automatic start of the engine 10, as exemplified by the broken line (d). As a result, the feeling of dragging the brake is almost eliminated, and the vehicle 1 moves forward smoothly and favorably on the downhill.
[0049]
As the hill hold control valves 80 and 90, for example, a proportional control valve using a DC solenoid can be used. However, since the on / off solenoid valves 80 and 90 are less expensive than proportional control valves and the like, the brake system of the vehicle 1 according to the embodiment using the on / off solenoid valves 80 and 90 has an advantage that the cost can be suppressed. is there.
[0050]
【The invention's effect】
As described above in detail with reference to specific examples, according to the present invention, in the idle stop vehicle, the reference pressure of the brake booster negative pressure used to determine whether to forcibly cancel the idle stop is set according to the road surface gradient. As a result, it was possible to achieve both the sufficient securing of the function of the brake booster and the sufficient achievement of the purpose of the idle stop. INDUSTRIAL APPLICABILITY The present invention is suitable for use in low-emission vehicles such as idle stop vehicles or environmentally friendly vehicles, and has wide industrial applicability in the general technical field of engines for vehicles such as automobiles.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing a power train and a brake system of an idle stop vehicle according to an embodiment of the present invention.
FIG. 2 is an enlarged configuration diagram illustrating a basic operation of the brake system, illustrating a brake pedal in a non-depressed state and an electromagnetic valve in an open state.
FIG. 3 illustrates a brake pedal in a depressed state and a solenoid valve in a closed state.
FIG. 4 is a system configuration diagram of the idle stop vehicle.
FIG. 5 is a flowchart illustrating an example of a specific operation of idle stop control executed by an idle stop control unit mounted on the idle stop vehicle.
FIG. 6 is a characteristic diagram showing a relationship between a reference pressure of a brake booster negative pressure used for determining whether to forcibly cancel idle stop, a road surface gradient, and a loaded weight.
FIG. 7 is a flowchart showing one example of a specific operation of hill hold control executed by a hill hold control unit mounted on the idle stop vehicle.
FIG. 8 is a time chart for explaining the operation of the embodiment.
[Explanation of symbols]
Reference Signs List 1 idle stop vehicle 10 engine 50 starter motor 71 brake pedal 72 brake booster 73 master cylinder 100 control unit for idle stop (automatic engine stop / start means, engine forced start means, reference pressure changing means)
160 Booster negative pressure sensor (brake booster negative pressure detecting means)
180 input key (load weight related value detection means)
200 Hill hold control unit (braking force holding means, braking force reducing means)
210 Inclination angle sensor (road surface gradient related value detecting means)

Claims (3)

  1. A brake booster utilizing an engine suction negative pressure is provided between the brake pedal and the master cylinder, a brake booster negative pressure detecting means for detecting a negative pressure introduced into the brake booster, and a predetermined engine stop when the vehicle stops. An engine automatic stop / start means for automatically stopping the engine when the condition is satisfied, and then automatically starting the engine when a predetermined engine start condition is satisfied; and the detecting means for automatically stopping the engine. An engine forcibly starting / starting the engine when the brake booster negative pressure detected in step (b) becomes higher than a predetermined reference pressure. Road slope related value detecting means for detecting a value related to Than when it is detected that a distribution, automatic stop and start system of a vehicle engine, characterized in that the reference pressure changing means to reduce the predetermined reference pressure is provided.
  2. A load weight related value detecting means for detecting a value related to the load weight of the vehicle is provided, and the reference pressure changing means detects that the load is large by the detecting means, compared to when the load is detected to be small. The automatic stop / start device for a vehicle engine according to claim 1, wherein the predetermined reference pressure is reduced.
  3. 2. The vehicle according to claim 1, further comprising: a braking force holding unit that holds a braking force that prevents the vehicle from moving when the vehicle is stopped, and a braking force reducing unit that reduces the held braking force when the vehicle starts moving. 3. The braking force holding device for a vehicle according to 2.
JP2002372312A 2002-12-24 2002-12-24 Automatic engine stopping and starting device for vehicle Pending JP2004204724A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009011281A1 (en) * 2009-03-02 2010-09-09 Dr.Ing.H.C.F.Porsche Aktiengesellschaft Method for operating an internal combustion engine
JP2011064188A (en) * 2009-09-19 2011-03-31 Toyota Motor Corp Engine controller
JP2011226316A (en) * 2010-04-15 2011-11-10 Advics Co Ltd Vehicle control device
JP2012102647A (en) * 2010-11-09 2012-05-31 Honda Motor Co Ltd Engine automatic stop restart device
JP2013119269A (en) * 2011-12-06 2013-06-17 Honda Motor Co Ltd Vehicular control device
JP5218661B2 (en) * 2010-09-22 2013-06-26 トヨタ自動車株式会社 Control device for internal combustion engine and control method for internal combustion engine
WO2013111175A1 (en) * 2012-01-23 2013-08-01 トヨタ自動車株式会社 Engine restart control device, vehicle, and vehicle control method
JP2014238101A (en) * 2014-09-26 2014-12-18 トヨタ自動車株式会社 Vehicle control device
JP2016016724A (en) * 2014-07-08 2016-02-01 本田技研工業株式会社 Vehicular control device
US9500155B2 (en) 2010-09-30 2016-11-22 Toyota Jidosha Kabushiki Kaisha Vehicle controller

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009011281A1 (en) * 2009-03-02 2010-09-09 Dr.Ing.H.C.F.Porsche Aktiengesellschaft Method for operating an internal combustion engine
JP2011064188A (en) * 2009-09-19 2011-03-31 Toyota Motor Corp Engine controller
JP2011226316A (en) * 2010-04-15 2011-11-10 Advics Co Ltd Vehicle control device
US8606485B1 (en) 2010-09-22 2013-12-10 Toyota Jidosha Kabushiki Kaisha Control device for internal combustion engine and control method for internal combustion engine
JP5218661B2 (en) * 2010-09-22 2013-06-26 トヨタ自動車株式会社 Control device for internal combustion engine and control method for internal combustion engine
US9500155B2 (en) 2010-09-30 2016-11-22 Toyota Jidosha Kabushiki Kaisha Vehicle controller
EP2622207B1 (en) * 2010-09-30 2018-10-24 Toyota Jidosha Kabushiki Kaisha Vehicle controller
JP2012102647A (en) * 2010-11-09 2012-05-31 Honda Motor Co Ltd Engine automatic stop restart device
JP2013119269A (en) * 2011-12-06 2013-06-17 Honda Motor Co Ltd Vehicular control device
JP5382260B1 (en) * 2012-01-23 2014-01-08 トヨタ自動車株式会社 Engine restart control device, vehicle, and vehicle control method
EP2808520A4 (en) * 2012-01-23 2016-04-20 Toyota Motor Co Ltd Engine restart control device, vehicle, and vehicle control method
WO2013111175A1 (en) * 2012-01-23 2013-08-01 トヨタ自動車株式会社 Engine restart control device, vehicle, and vehicle control method
CN103328791A (en) * 2012-01-23 2013-09-25 丰田自动车株式会社 Engine restart control device, vehicle and vehicle control method
JP2016016724A (en) * 2014-07-08 2016-02-01 本田技研工業株式会社 Vehicular control device
JP2014238101A (en) * 2014-09-26 2014-12-18 トヨタ自動車株式会社 Vehicle control device

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